JP5763517B2 - Organic EL device - Google Patents

Description

  The present invention relates to an organic EL element.

  Organic electroluminescence elements (organic EL elements) are used as self-luminous elements as video display devices such as displays and as surface light sources. Such an organic EL element is generally produced by sequentially laminating a transparent electrode as an anode, an organic layer, and a metal electrode as a cathode on a transparent support substrate such as a glass substrate or a transparent plastic film. It is what is done. In this way, the electrons applied from the cathode and the holes supplied from the anode are recombined in the organic layer due to the voltage applied between the transparent electrode and the metal electrode, and excitons generated accordingly. EL emits light when it shifts from the excited state to the ground state. The light emitted from the EL is transmitted through the transparent electrode and taken out from the transparent support substrate side.

  However, such an organic EL element has a problem that light generated in the organic layer cannot be sufficiently extracted outside. That is, most of the light generated in the organic layer disappears due to heat while repeating multiple reflections inside the element, or is guided from inside the element and emitted from the end of the element. Therefore, there has been a problem that sufficient external extraction efficiency cannot be achieved. Therefore, in recent years, in the field of organic EL elements, it has been proposed to improve the efficiency of extracting light to the outside by using a diffraction grating having a concavo-convex shape.

As an organic EL element using a diffraction grating having such a concavo-convex shape, for example, in International Publication No. 2011/007878 (Patent Document 1), a transparent support substrate (A) is formed on the transparent support substrate. An organic EL element comprising a laminated cured resin layer (B), a transparent electrode (C), an organic layer (D), and a metal electrode (E) sequentially laminated on the cured resin layer (B). The cured resin layer (B) has irregularities formed on the surface, and the irregularity image obtained by analyzing the irregularity shape using an atomic force microscope is subjected to a two-dimensional fast Fourier transform process. When a transformed image is obtained, the Fourier transformed image shows a circular or annular pattern whose center is the origin whose absolute value of the wave number is 0 μm ⁻¹ , and the circular or annular shape absolute value of 10μm pattern, of the wave number of the A shape existing in the region to be a range of ¹ or less, the organic EL element is disclosed. Although such an organic EL element described in Patent Document 1 has sufficiently high light extraction efficiency, the appearance of an organic EL element capable of improving the light extraction efficiency at a higher level is desired. ing.

  On the other hand, in the field of organic EL elements, even if light generated in the organic layer is extracted from the transparent electrode (for example, ITO film), a transparent supporting substrate (for example, glass) in which part of the light exists outside the transparent electrode. It is also known that reflection is repeated in a substrate or the like made of and confined in a transparent support substrate. As a method for extracting light confined in such a transparent support substrate, conventionally, a lens or the like is used to prevent light from being totally reflected at the interface between the transparent support substrate and air and extract the light. Techniques have been proposed. As described above, when a lens or the like is used, the light extraction efficiency is improved even in the conventional organic EL element, but an organic EL element capable of improving the light extraction efficiency at a higher level is desired. Yes. In the above-mentioned Patent Document 1, there is no particular description about using a lens for extracting light or using phosphorescent light emission for light emission of an element.

International Publication 2011/007878

  The present invention has been made in view of the above-described problems of the prior art, and can improve the light extraction efficiency of the organic EL element at a higher level and achieve a sufficiently high luminous efficiency. An object is to provide a possible organic EL element.

  As a result of intensive studies to achieve the above object, the present inventors have found that a transparent support substrate, an uneven layer disposed on one surface side of the transparent support substrate and having a first unevenness formed on the surface thereof, A diffraction electrode, a transparent electrode sequentially laminated on the diffraction grating so as to maintain the shape of the first unevenness formed on the surface of the diffraction grating, an organic layer including at least a light emitting layer, and In an organic EL element comprising a metal electrode and an optical member arranged on the other surface side of the transparent support substrate, the element satisfies the conditions (A) to (C) described below, It has been found that the light extraction efficiency of the organic EL element can be improved at a higher level, and a sufficiently high luminous efficiency can be achieved, and the present invention has been completed.

That is, the organic EL element of the present invention includes a transparent support substrate,
A diffraction grating composed of a concavo-convex layer disposed on one surface side of the transparent support substrate and having a first concavo-convex formed on the surface thereof,
A transparent electrode, an organic layer having at least a light emitting layer, a metal electrode, and a metal electrode, which are sequentially stacked on the diffraction grating so that the shape of the first unevenness formed on the surface of the diffraction grating is maintained. ,
An optical member disposed on the other surface side of the transparent support substrate;
An organic EL device comprising:
The following conditions (A) to (C):
[Condition (A)] When the unevenness analysis image obtained by analyzing the shape of the first unevenness using an atomic force microscope is subjected to a two-dimensional fast Fourier transform process to obtain a Fourier transform image, the Fourier transform image is obtained. The converted image shows a circular or annular pattern whose center is the origin where the absolute value of the wave number is 0 μm ⁻¹ , and the absolute value of the wave number is 10 μm ⁻ Be in an area that is within ¹ or less,
[Condition (B)] Each of the first unevenness and the second unevenness formed on the surface of the surface facing the organic layer of the metal electrode is analyzed using an atomic force microscope. The standard deviation of the depth distribution of the unevenness obtained based on the unevenness analysis image obtained as described above is 15 to 50 nm,
[Condition (C)] The rate of change of the standard deviation of the depth distribution of the second unevenness with respect to the standard deviation of the depth distribution of the first unevenness is + 15% to −15%.
That it meets,
The unevenness formed on the surface of the transparent electrode and the surface of the organic layer facing the metal electrode of each layer having a thickness of 10 nm or more has a standard deviation of the unevenness depth distribution of 15 to 50 nm. And the rate of change of the standard deviation of the unevenness depth distribution with respect to the standard deviation of the depth distribution of the first unevenness is + 15% to −15%,
The material constituting the organic layer is an organic material having a glass transition temperature of 70 ° C. to 300 ° C.,
The organic layer further comprises a hole transport layer and an electron transport layer, and the light emitting layer is a layer containing a phosphorescent material and a host material; and
The light emitting layer has a two-layer structure of a first light emitting layer and a second light emitting layer, and the types of host materials of the first light emitting layer and the second light emitting layer are different from each other;
It is characterized by.

  In the organic EL device of the present invention, the transparent electrode and each layer having a thickness in the organic layer of 10 nm or more (each layer satisfying a condition in which the thickness in the organic layer is 10 nm or more). All of the irregularities formed on the surface of the surface facing the metal electrode have a standard deviation of the irregularity depth distribution of 15 to 50 nm, and the standard deviation of the depth distribution of the first irregularities. It is preferable that the change rate of the standard deviation of the uneven depth distribution is + 15% to −15%. In addition, the condition of “each layer in which the thickness in the organic layer is 10 nm or more” here is basically that the shape of the first unevenness is maintained because the layer having a thickness of less than 10 nm is thin. In the case of laminating by a known method such as vapor deposition or sputtering while appropriately selecting the conditions as described above, the characteristics of the uneven shape formed on the surface of the object to be laminated (laminated object) are maintained sufficiently. When the above conditions are satisfied in a layer having a thickness of 10 nm or more among the organic layers, the ratio of the change in the shape of the concavo-convex shape during the lamination is sufficiently low. The conditions are defined from the fact that all the layers in the organic layer can be regarded as satisfying the above condition.

  In the organic EL device of the present invention, the transparent electrode and each layer of the organic layer (all layers including a layer having a thickness of less than 10 nm) are formed on the surface of the surface facing the metal electrode. In any of the unevennesses, the standard deviation of the unevenness depth distribution is 15 to 50 nm, and the change rate of the standard deviation of the unevenness depth distribution with respect to the standard deviation of the unevenness depth distribution of the first unevenness is It is more preferable to be + 15% to −15%.

  In the organic EL element of the present invention, the material constituting the organic layer is preferably an organic material having a glass transition temperature of 70 ° C to 300 ° C. By configuring the organic layer with an organic material having a glass transition temperature in such a temperature range, it tends to be possible to obtain an organic EL element that satisfies the above conditions (A) to (C) more efficiently. The “material constituting the organic layer” as used herein refers to a light emitting layer excluding the dopant material when the light emitting layer is a layer containing a host material and a dopant material (for example, a phosphorescent material or a fluorescent material). The material which consists of the material (host material) which forms and the material which forms the other layer of an organic layer.

  In the organic EL device of the present invention, the configuration of the light emitting layer is not particularly limited, and may include a host material and a dopant material (for example, a phosphorescent material or a fluorescent material) as described above. Such a light emitting layer is preferably a layer containing a host material and a phosphorescent material. In the organic EL device of the present invention, the organic layer further includes a hole transport layer and an electron transport layer, and the light emitting layer is a layer containing a phosphorescent material and a host material. preferable. In this case, holes accumulate between the light emitting layer and the electron transport layer (for example, in the case of providing a hole blocking layer, the holes are accumulated), or electrons are positively connected to the light emitting layer. If it accumulates between the hole transport layer (for example, when an electron blocking layer is provided, the interface between the light emitting layer and the electron blocking layer), recombination of electrons and holes occurs at those interfaces, and the triplet excited state is From the viewpoint of minimizing (minimizing) the light emitting layer, the light emitting layer has a two-layer structure of a first light emitting layer and a second light emitting layer, and the first light emitting layer More preferably, the type of the host material of the second light emitting layer is different. As described above, when the organic layer further includes a hole transport layer and an electron transport layer, and the light emitting layer is a layer containing a phosphorescent material and a host material, the hole transport layer From the viewpoint that the interface between the light-emitting layer and the light-emitting layer is substantially eliminated, and a decrease in light emission efficiency due to a decrease in energy barrier and carrier mobility at the interface can be sufficiently suppressed. More preferably, the host material is made of the same material. The light-emitting layer includes a hole transport layer and an electron transport layer, the light-emitting layer has a two-layer structure of a first light-emitting layer and a second light-emitting layer, and the first light-emitting layer and the When the types of host materials of the second light emitting layer are different from each other, the material constituting the hole transport layer and the host material of the first light emitting layer are made of the same material, and constitute the electron transport layer. It is preferable that the material and the host material of the second light emitting layer are made of the same material.

  Moreover, in the organic EL element of the said invention, it is preferable that the said host material which comprises the said light emitting layer is an organic material whose glass transition temperature is 100 to 300 degreeC.

  Furthermore, in the organic EL element of the present invention, the average height of the irregularities formed on the surface of the diffraction grating is preferably in the range of 20 to 200 nm.

  Moreover, in the organic EL element of the present invention, it is preferable that the average pitch of the unevenness formed on the surface of the diffraction grating is in the range of 100 to 700 nm.

  Further, in the organic EL element of the present invention, the uneven layer of the diffraction grating may be a cured resin layer or an inorganic layer, and is not particularly limited, but has more characteristics such as heat resistance and mechanical strength. From the viewpoint of becoming high, the uneven layer is preferably an inorganic layer.

  Furthermore, in the organic EL element of the present invention, the optical member is preferably a lens member.

  The reason why the organic EL element of the present invention can improve the light extraction efficiency of the organic EL element at a higher level and can achieve a sufficiently high luminous efficiency is not necessarily clear. However, the present inventors infer as follows. That is, first, in the present invention, a diffraction grating satisfying the above condition (A) is arranged on one surface side of the transparent support substrate. By using an uneven diffraction grating satisfying such a condition (A), it is possible to suppress the light generated in the organic layer from being reflected at the interface of the organic layer and repeating multiple reflections inside the element, The light reflected at the interface between the transparent support substrate and air can be re-emitted by the diffraction effect, and the light extraction efficiency can be improved. In the present invention, the first unevenness and the second unevenness both have a standard deviation of the unevenness depth distribution of 15 to 50 nm (condition (B)). By achieving such a standard deviation of the unevenness depth distribution, it is possible to keep the electric field strength distribution constant over the entire element while preventing a decrease in diffraction efficiency due to unevenness flattening. Generation of local electric field concentration and leakage current is suppressed while obtaining a diffraction effect. Furthermore, in the present invention, the rate of change of the standard deviation of the second unevenness depth distribution with respect to the standard deviation of the first unevenness depth distribution is + 15% to −15% (condition (C )). Thus, when the rate of change of the standard deviation between the first unevenness and the second unevenness is + 15% to −15%, the first unevenness and the second unevenness The followability of the uneven shape is sufficiently high. And when the followability of the shape of the unevenness is high between the first unevenness and the second unevenness, the distance between the surfaces of the first unevenness and the second unevenness is Since the uniformity is high, the occurrence of a part where the distance between the layers is extremely long or a part where the distance is extremely short is sufficiently prevented (prevention of non-uniform distance between the layers). Therefore, the present inventors speculate that satisfying the condition (C) sufficiently suppresses local electric field concentration and occurrence of leakage current in a portion where the distance between layers is not uniform. As described above, in the present invention, the first unevenness and the second unevenness formed on the surface of the metal electrode while the diffraction grating having the first unevenness satisfies the condition (A). And satisfying the above conditions (B) to (C), it is possible to sufficiently suppress the occurrence of local electric field concentration and leakage current while obtaining a sufficiently high diffraction effect. The present inventors infer that the light extraction efficiency can be sufficiently stably improved, and thereby the light emission efficiency can be sufficiently improved. Further, in the organic EL device of the present invention, local electric field concentration can be sufficiently suppressed. Therefore, when a phosphorescent device suitable for the present invention is formed (the light emitting layer includes a host material and a phosphorescent material). Even in the case of inclusion, it is possible to sufficiently suppress the occurrence of a so-called roll-off phenomenon in which the triplet excited state of the phosphorescent material disappears due to electric field concentration, thereby sufficiently suppressing the decrease in the luminous efficiency of phosphorescence. Thus, in the organic EL element of the present invention, the light emission efficiency can be sufficiently improved due to the sufficiently suppressed local electric field concentration. In the present invention, an optical member is disposed on the other surface side of the transparent support substrate (the surface opposite to the surface on which the diffraction grating is disposed on the transparent support substrate: the light extraction surface side). . In order to take out the light outside the element in this manner, by arranging the optical member, the light that repeats reflection in the transparent support substrate outside the diffraction grating and is confined in the substrate can be efficiently externalized. In combination with the use of a diffraction grating, light generated in the organic layer can be extracted to the outside at a very high level. As described above, in the present invention, since the diffraction grating satisfying the above conditions (A) to (C) is used and the optical member for further extracting light to the outside is used on the light extraction surface side, the luminous efficiency is improved. The present inventors speculate that it can be more sufficiently improved.

  According to the present invention, it is possible to provide an organic EL element that can improve the light extraction efficiency of the organic EL element at a higher level and can achieve a sufficiently high luminous efficiency. .

It is sectional drawing which shows typically suitable one Embodiment of the organic EL element of this invention. It is a conceptual diagram which shows notionally the thickness between recessed parts and the thickness between convex parts based on arbitrary 2 layers in an organic layer. It is sectional drawing which forms typically the layer which consists of a 1st polymer segment which has the unevenness | corrugation of a mountain-shaped structure, and shows one Embodiment of a base material (master for transcription | transfer). It is sectional drawing which shows typically the state by which the layer which consists of the 1st polymer segment which has the unevenness | corrugation of a chevron structure was formed, and the seed layer was laminated | stacked on the unevenness | corrugation of the surface of a base material (transfer master). It is sectional drawing which shows typically the state by which the metal layer was formed on the seed layer. It is sectional drawing which shows typically the state which peeled from the master for transfer the metal part (matrix) which consists of the metal layer and seed layer which were laminated | stacked on the surface of the master for transfer. It is sectional drawing which shows typically the state which apply | coated the diffraction grating formation material on the transparent support substrate. It is sectional drawing which shows typically the state which hardened the diffraction grating formation material, pressing the matrix for diffraction grating formation. FIG. 3 is a cross-sectional view schematically showing a state in which the matrix for forming a diffraction grating is removed and irregularities are formed on the surface of a hardened layer of the diffraction grating forming material. It is sectional drawing which shows typically other suitable embodiment of the organic EL element of this invention. It is sectional drawing which shows typically other suitable embodiment of the organic EL element of this invention. It is a photograph which shows the Fourier-transform image which displayed on the display the result of the two-dimensional fast Fourier-transform process for the unevenness | corrugation analysis image by the atomic force microscope of the surface of the diffraction grating obtained in Reference Example 1. FIG. 2 is an electron micrograph of a cross section of an organic EL element obtained in Reference Example 1. 2 is an electron micrograph of a cross section of an organic EL element obtained in Reference Example 1. 4 is an electron micrograph of a cross section of an organic EL element obtained in Comparative Example 1.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. In the following description and drawings, the same or corresponding elements are denoted by the same reference numerals, and duplicate descriptions are omitted.

The organic EL device of the present invention comprises a transparent support substrate,
A diffraction grating composed of a concavo-convex layer disposed on one surface side of the transparent support substrate and having a first concavo-convex formed on the surface thereof,
A transparent electrode, an organic layer having at least a light emitting layer, a metal electrode, and a metal electrode, which are sequentially stacked on the diffraction grating so that the shape of the first unevenness formed on the surface of the diffraction grating is maintained. ,
An optical member disposed on the other surface side of the transparent support substrate;
An organic EL device comprising:
The following conditions (A) to (C):
[Condition (A)] When the unevenness analysis image obtained by analyzing the shape of the first unevenness using an atomic force microscope is subjected to a two-dimensional fast Fourier transform process to obtain a Fourier transform image, the Fourier transform image is obtained. The converted image shows a circular or annular pattern whose center is the origin where the absolute value of the wave number is 0 μm ⁻¹ , and the absolute value of the wave number is 10 μm ⁻ Be in an area that is within ¹ or less,
[Condition (B)] Each of the first unevenness and the second unevenness formed on the surface of the surface facing the organic layer of the metal electrode is analyzed using an atomic force microscope. The standard deviation of the depth distribution of the unevenness obtained based on the unevenness analysis image obtained as described above is 15 to 50 nm,
[Condition (C)] The rate of change of the standard deviation of the depth distribution of the second unevenness with respect to the standard deviation of the depth distribution of the first unevenness is + 15% to −15%.
It is characterized by satisfying.

  FIG. 1 is a cross-sectional view schematically showing a preferred embodiment of the organic EL device of the present invention. The organic EL element according to the embodiment shown in FIG. 1 includes a transparent support substrate 10, a diffraction grating 11 that is arranged on one surface side of the transparent support substrate 10, and has a concavo-convex layer with concavo-convex formed on the surface. On the other surface side of the transparent electrode 12, the organic layer 13, the metal electrode 14, and the transparent support substrate 10 that are sequentially laminated on the diffraction grating 11 so that the shape of the irregularities formed on the surface is maintained. The arranged optical member 15 is provided. In the organic EL element of the embodiment shown in FIG. 1, the organic layer 13 has a stacked structure including a hole transport layer 131, a light emitting layer 132, and an electron transport layer 133.

<Transparent support substrate 10>
It does not restrict | limit especially as the transparent support substrate 10, The well-known transparent substrate which can be used for an organic EL element can be utilized suitably, For example, a board | substrate consisting of transparent inorganic materials, such as glass; Polyethylene terephthalate (PET), A substrate made of a resin such as polyethylene telenaphthalate (PEN), polycarbonate (PC), cycloolefin polymer (COP), polymethyl methacrylate (PMMA), polystyrene (PS); SiN, SiO _{2 on} the surface of the substrate made of these resins , SiC, SiO _x N _y , TiO ₂ , TiO ₂ , Al ₂ O ₃ etc. laminated substrate formed by forming a gas barrier layer; these resin substrates and these inorganic gas barrier layers are alternately laminated And a laminated substrate. The thickness of the transparent support substrate 10 is preferably in the range of 1 to 2000 μm.

<Diffraction grating 11>
The diffraction grating 11 is composed of a concavo-convex layer having a first concavo-convex formed on the surface thereof. Examples of the material for forming such a diffraction grating 11 (concave / convex layer) include resin materials such as epoxy resin, acrylic resin, urethane resin, melamine resin, urea resin, polyester resin, phenol resin, and cross-linkable liquid crystal resin. And a transparent inorganic layer forming material (for example, in the case of forming an uneven layer by a sol-gel method to form a transparent inorganic layer, a sol solution containing a metal material such as a metal alkoxide is included). Thus, the diffraction grating 11 (uneven layer) may be a cured resin layer obtained by curing the resin material or an inorganic layer formed using a transparent inorganic layer forming material. From the viewpoint of obtaining a layer having characteristics such as high heat resistance and mechanical strength, an inorganic layer is preferable. The thickness of the diffraction grating 11 is preferably in the range of 0.01 to 500 μm. If the thickness of the diffraction grating 11 is less than the lower limit, the height of the unevenness formed on the surface of the diffraction grating 11 tends to be insufficient. On the other hand, if the thickness exceeds the upper limit, the volume change caused during curing is greatly affected. Therefore, the uneven shape tends to be unable to be formed satisfactorily.

Moreover, in the diffraction grating 11, the 1st unevenness | corrugation which satisfy | fills the said conditions (A) is formed. In other words, the diffraction grating 11 performs a two-dimensional fast Fourier transform process on a concavo-convex analysis image obtained by analyzing the shape of the first concavo-convex formed on the surface using an atomic force microscope, and generates a Fourier transform image. In the obtained case, the Fourier transform image shows a circular or annular pattern substantially centered on the origin whose absolute value of the wave number is 0 μm ⁻¹ and the Fourier transform of the first uneven shape. The circular or annular pattern of the image needs to be present in a region where the absolute value of the wave number is in the range of 10 μm ⁻¹ or less. When the Fourier transform image satisfies the above condition (A), the diffraction grating 11 has a sufficiently small wavelength dependency and directivity and a sufficient diffraction effect.

Further, the pattern of such a Fourier transform image is more preferably an annular shape from the viewpoint that a higher effect can be obtained in terms of wavelength dependency and directivity. Similarly, from the viewpoint of obtaining a further advanced effect in terms of wavelength dependency and directivity, the circular or annular pattern of the Fourier transform image has an absolute value of wave number of 1.25 to 10 μm ^−1. More preferably, it exists in the area | region which becomes in the range of (more preferably 1.25-5 micrometers- ¹ ).

  The “circular or annular pattern of the Fourier transform image” referred to in the present invention is a pattern observed when bright spots are gathered in the Fourier transform image. Therefore, the “circular shape” in the present invention means that a pattern in which bright spots are gathered appears to be a substantially circular shape, and includes those in which a part of the outer shape appears to be convex or concave. It is a concept, and “annular” means that the pattern of bright spots appears to be almost circular, and the outer circle and inner circle appear to be almost circular. And a part of the outer circle of the ring or a part of the outer shape of the inner circle that appears to be convex or concave.

Moreover, the range of in the present invention the absolute value of "a circular or annular pattern wavenumber 10 [mu] m ^-1 or less (preferably 1.25～10Myuemu ^-1, more preferably 1.25~5μm ^-1) "Is present in the region" means that 30% or more (more preferably 50% or more, still more preferably 80% or more, particularly preferably 90% or more) of the luminescent spots constituting the Fourier transform image. there absolute value of wavenumber 10 [mu] m ^-1 or less (preferably 1.25~10μm ^-1, more preferably 1.25~5μm ^-1) means that existing in the region to be a range of.

The Fourier transform image is obtained by analyzing the shape of the unevenness formed on the surface of the uneven layer using an atomic force microscope to obtain an unevenness analysis image, and then performing a two-dimensional fast Fourier transform process on the unevenness analysis image. It is obtained by applying. The unevenness analysis image is analyzed using an atomic force microscope under the following analysis conditions:
Measuring method: Cantilever intermittent contact method Cantilever material: Silicon cantilever lever width: 40μm
Cantilever tip tip diameter: 10 nm
Can be obtained by analysis.

  As such an atomic force microscope, a commercially available one can be used as appropriate, and, for example, a scanning probe microscope “Nonavi II station / E-sweep” with an environmental control unit manufactured by SII Nanotechnology is used. be able to. In addition, as a measurement method of the atomic force microscope, it is preferable to employ a cantilever intermittent contact method, but when using a scanning probe microscope with an environmental control unit manufactured by SII Nanotechnology, a dynamic force mode ( DMF mode) can be used. Further, it is preferable to use a cantilever having a material of silicon, a lever width of 40 μm, and a tip tip diameter of 10 nm. For example, SI-DF40 can be used. Moreover, when analyzing using the said atomic force microscope, it is preferable to observe the shape of the unevenness | corrugation currently formed in the surface of the said uneven | corrugated layer by making temperature into 25 degreeC in air | atmosphere.

  The two-dimensional fast Fourier transform processing of the unevenness analysis image can be easily performed by electronic image processing using a computer equipped with two-dimensional fast Fourier transform processing software. In such a two-dimensional fast Fourier transform process, it is preferable to perform a flat process including a first-order inclination correction on the unevenness analysis image. In addition, as the unevenness analysis image subjected to such a two-dimensional fast Fourier transform process, an unevenness analysis image having a display range of 3 μm square (vertical 3 μm, horizontal 3 μm) can be used.

  Further, in the diffraction grating 11, the standard deviation (σ) of the depth distribution of the first unevenness formed on the surface needs to be 15 to 50 nm. When the standard deviation (σ) of the depth distribution of the first unevenness is less than the lower limit, a sufficient diffraction effect cannot be obtained, and it becomes difficult to sufficiently improve the light extraction efficiency. On the other hand, when the standard deviation (σ) of the depth distribution of the first unevenness exceeds the upper limit, there are many portions where the distance between the anode and the cathode is short. As a result, a sufficient leakage efficiency cannot be obtained. Note that when local electric field concentration occurs, the electric field concentrates at a specific location, and heat is generated to cause destruction of the element, which tends to shorten the lifetime. In addition, the standard deviation (σ) of the depth distribution of the first unevenness is preferably 17 to 40 nm because a higher effect can be obtained from the same viewpoint as the upper limit value and the lower limit value. More preferably, it is 18-30 nm.

  In the present invention, the standard deviation of the depth distribution of the uneven shape of the uneven shape is represented by the following formula (I):

[In formula (I), N represents the total number of measurement points (total number of pixels), x _i represents the data of the depth of unevenness of the i-th measurement point, and i is any of integers from 1 to N M represents the average value of the depth distribution of the unevenness. ]
Can be obtained by calculating. Further, the average value (m) of the depth distribution of the unevenness in the formula (I) is measured by the following method. That is, in such a method for measuring the average value (m) of the uneven depth distribution, first, the uneven shape is measured using a scanning probe microscope (for example, product name “E-N” manufactured by SII Nano Technology Co., Ltd.). ”sweep” or the like) to measure the unevenness analysis image. In this way, when analyzing unevenness, an unevenness analysis image is obtained by measuring an arbitrary measurement area of 3 μm square (3 μm in length and 3 μm in width) under the above-described analysis conditions. In that case, the data of the unevenness | corrugation height in the measurement point more than 16384 points (vertical 128 points x horizontal 128 points) in a measurement area | region are each calculated | required by a nanometer scale. The total number (N) of such measurement points varies depending on the type and setting of the measurement device used. For example, the product name “E-” manufactured by SII NanoTechnology Co., Ltd. is used as the measurement device. When “sweep” is used, the total number (N) of the measurement points in the measurement area of 3 μm square can be 65536 points (256 vertical points × 256 horizontal points), and the measurement points are 65536 measurement points ( Measurement at a resolution of 256 × 256 pixels). And regarding the uneven | corrugated height (unit: nm) measured in each measurement point in this way, first, the measurement point with the highest height from the surface of the transparent support substrate 10 is calculated | required among all the measurement points. Then, a plane including the measurement point and parallel to the surface of the transparent support substrate 10 is defined as a reference plane (horizontal plane), and a depth value from the reference plane (in the case of the diffraction grating 11, the transparent support substrate 10 at the measurement point). The difference obtained by subtracting the height from the transparent support substrate 10 at each measurement point from the height value from is obtained as the data of the unevenness depth. It should be noted that such unevenness depth data may be automatically calculated and obtained by software or the like in the measuring device depending on the measuring device (for example, product name “E-sweep” manufactured by SII Nano Technology Co., Ltd.). The value obtained by such automatic calculation can be used as the depth data. Thus, after calculating | requiring the data of the uneven | corrugated depth in each measurement point, the average value (m) of the uneven | corrugated depth distribution is following formula (II):

Wherein (II), N represents the total number of measurement points (total number of pixels), i represents any of integers from 1 to N, x _i is the i-th measurement point uneven depth Data is shown, m shows the average value of the uneven | corrugated depth distribution. ]
Can be obtained by calculating.

  Moreover, in such a diffraction grating 11, it is preferable that the average value (m) of the depth distribution of 1st unevenness | corrugation is 30-70 nm, and it is more preferable that it is 40-60 nm. If the average value (m) of such a depth distribution is less than the lower limit, a sufficient diffractive effect cannot be obtained because the unevenness depth is shallow, and it tends to be difficult to sufficiently improve the luminous efficiency. On the other hand, if the upper limit is exceeded, the aspect ratio of the concavities and convexities increases, so that when used in an organic EL element, not only does the electrode easily crack, but also leakage current is likely to occur during use, and the luminous efficiency is improved. In some cases, the light emission is reduced or no light is emitted at all, and the lifetime of the organic EL element tends to be shortened.

Further, the diffraction grating 11 has an average value and a median value of the depth distribution of the first unevenness formed on the surface thereof, the following inequality (1):
0.95 × Y ≦ M ≦ 1.05 × Y (1)
[In the formula (1), Y represents a value obtained by calculating the formula: Y = 1.07 m-2.25 (where m represents an average value of the depth distribution of unevenness), and M represents The median value of the uneven depth distribution is shown. ]
It is preferable that the condition represented by When such median value (M) and average value (m) satisfy the above conditions, it is possible to sufficiently suppress the occurrence of leakage current when used in an organic EL element. The median value (M) of the uneven depth distribution in inequality (1) is based on the uneven depth data at each measurement point when measuring the average value (m). When the concavo-convex depth data x _i at all measurement points is rearranged in ascending order and expressed as x _(i) (in this case, the height order is x ₍₁₎ <x ₍₂₎ <x _{(3 )} <... <x _(N))) , depending on whether N is an odd number or an even number, the following formula (III):

[In Formula (III), N represents the total number of measurement points (total number of pixels), and M represents the median value of the depth distribution of the unevenness. ]
It can be obtained by calculating any of the formulas.

  Further, in the diffraction grating 11, the kurtosis of the irregularities formed on the surface of the diffraction grating 11 is preferably −1.2 or more, more preferably −1.2 to 1.2, 1.2 to 1 is more preferable, and −1.1 to 0.0 is particularly preferable. If the kurtosis is less than the lower limit, it tends to be difficult to sufficiently suppress the occurrence of leakage current when used in an organic EL element. Since the shape is almost uneven and there are sparse protrusions or depressions, the light extraction efficiency, which is a feature of the uneven structure, cannot be sufficiently improved (a sufficient diffraction effect cannot be obtained). The electric field tends to concentrate on the protrusions, and a leak current tends to occur.

  As a method for measuring such kurtosis, the following method is adopted. That is, first, in the same manner as the measurement method of the average value (m) of the depth distribution, more than 16384 points (128 vertical points × 128 horizontal points) in the measurement area of 3 μm square (for example, SII Nanotechnology Corporation as a measuring device) When the product name “E-sweep” manufactured by the company is used, data on the unevenness depth is obtained at 65536 measurement points. Then, based on the data of the unevenness depth at each measurement point, based on the above formulas (I) and (II), the average value (m) of the unevenness depth distribution and the standard deviation of the unevenness depth distribution (σ ). Next, based on the average value (m) and the standard deviation (σ) values thus obtained, the kurtosis (k) is expressed by the following formula (IV):

Wherein (IV), N represents the total number of measurement points (total number of pixels), x _i denotes the data of the i-th uneven depth measuring points, m represents the average value of the depth distribution of the irregularities , Σ indicates a standard deviation. ]
Can be obtained by calculating.

  Moreover, in the diffraction grating 11, it is preferable that the average height of 1st unevenness | corrugation is 20-200 nm, It is more preferable that it is 30-100 nm, It is still more preferable that it is 40-80 nm. If the average height of the first irregularities is less than the lower limit, the height is too low with respect to the wavelength of visible light, so that necessary diffraction tends not to occur. When the diffraction grating is used as an optical element on the light extraction port side of an organic EL element, the electric field distribution inside the EL layer becomes non-uniform and the electric field concentrates on a specific location, so that the element is destroyed and its life is shortened. In addition, there is a tendency that it is difficult to reproduce irregularities by nanoimprint. The “average height of the first unevenness” as used herein refers to the case where the height of the unevenness on the surface of the diffraction grating 11 (the distance in the depth direction between the concave portion and the convex portion) is measured as follows. The average value of the height of the irregularities. The average value of the height of such irregularities is obtained by analyzing the shape of the irregularities on the surface using the scanning probe microscope (for example, product name “E-sweep” manufactured by SII Nano Technology Co., Ltd.). After measuring an unevenness analysis image in an arbitrary measurement region (preferably an arbitrary measurement region of 3 μm square) under the conditions, the distance in the depth direction from the arbitrary concave portion and the convex portion in the unevenness analysis image is 100 points or more. Measure and adopt the value calculated by calculating the average.

  Furthermore, in the diffraction grating 11, it is preferable that the average pitch of 1st unevenness | corrugation is the range of 10-700 nm, and it is more preferable that it is the range of 100-700 nm. If the average pitch of the first irregularities is less than the lower limit, the pitch tends to be too small with respect to the wavelength of visible light, so that necessary diffraction does not tend to occur. The function as a lattice tends to be lost. The average pitch of the first unevenness is the pitch of the first unevenness when the pitch of the first unevenness on the surface of the diffraction grating 11 (the interval between adjacent convex portions or adjacent concave portions) is measured. It means the average value of. In addition, the average value of the pitch of the first unevenness is measured using the scanning probe microscope (for example, product name “E-sweep” manufactured by SII Nano Technology Co., Ltd.) under the above-described analysis conditions. After measuring the unevenness and measuring the unevenness analysis image, it can be calculated by measuring the interval between any adjacent convex portions or adjacent concave portions in the unevenness analysis image at 100 points or more and calculating the average. Adopt value.

  A method for manufacturing such a diffraction grating 11 will be described later. In addition, the standard deviation (σ) of the uneven depth distribution, the average value (m) of the uneven depth distribution, the inequality (1), the average height of the unevenness, and the pitch of the unevenness are satisfied. One unevenness can be easily formed by using a method for manufacturing the diffraction grating 11 (a manufacturing method using a mother die) described later.

<Transparent electrode 12>
The transparent electrode 12 is laminated on the diffraction grating so that the shape of the first unevenness is maintained, and the surface (both sides) has unevenness derived from the shape of the first unevenness. Is formed. In such a transparent electrode 12, unevenness (hereinafter referred to as “third unevenness” in some cases) formed on the surface of the surface facing the metal electrode (the surface opposite to the surface facing the diffraction grating). The standard deviation (σ) of the depth distribution is preferably 15 to 50 nm, preferably 17 to 40 nm, and more preferably 18 to 30 nm. When the standard deviation (σ) of the depth distribution of the third unevenness is less than the lower limit, a sufficient diffraction effect cannot be obtained, and it tends to be difficult to sufficiently improve the light extraction efficiency, If the upper limit is exceeded, there will be many sites with a short anode-cathode distance, and in the resulting device, local electric field concentration, leakage current, etc. will occur, making it impossible to obtain sufficient luminous efficiency. There is a tendency.

Further, in the transparent electrode 12, the change rate of the standard deviation of the third unevenness depth distribution with respect to the standard deviation of the first unevenness depth distribution is + 15% to −15% (more preferably + 10% to −−). 10%, more preferably + 8% to -8%). If the rate of change exceeds the upper limit, local electric field concentration tends to occur, and leakage current and device deterioration tend to occur. In addition, the element tends to deteriorate and the diffraction effect due to the unevenness tends to decrease, and the light extraction efficiency tends to decrease. The rate of change is given by the following formula:
[Change rate] = {([Standard deviation of depth distribution of third unevenness] − [Standard deviation of depth distribution of first unevenness]) / [Standard deviation of depth distribution of first unevenness]} × 100
Can be calculated.

  In addition, the suitable range of the average height and average pitch of the third unevenness in the transparent electrode 12 may be the same range from the same viewpoint as the preferred range of the average height and average pitch of the first unevenness. preferable. As the third unevenness, the kurtosis of the unevenness preferably satisfies the same conditions as the first unevenness, and preferably satisfies the inequality (1). Note that the third unevenness characteristic of the transparent electrode 12 is such that after the transparent electrode 12 is formed, the unevenness on the surface of the transparent electrode 12 is changed to the unevenness characteristic of the diffraction grating 11 (standard of unevenness depth distribution). It can be determined by adopting the same method as the measuring method of the characteristic (deviation (σ) etc.).

  The material for the transparent electrode 12 is not particularly limited, and any material that can be used as a transparent electrode for an organic EL element can be used as appropriate. Examples thereof include indium oxide, zinc oxide, tin oxide, and composites thereof. Indium tin oxide (ITO), gold, platinum, silver, copper and the like can be used. Among such materials for the transparent electrode 12, ITO is preferable from the viewpoint of balance between transparency and conductivity. The thickness of the transparent electrode 12 is preferably in the range of 20 to 500 nm. If the thickness is less than the lower limit, the conductivity tends to be insufficient. On the other hand, if the thickness exceeds the upper limit, the transparency is insufficient and the emitted EL light tends not to be taken out sufficiently.

<Organic layer 13>
The organic layer 13 is a layer laminated so that the shape of the first unevenness is maintained, and unevenness derived from the shape of the first unevenness is formed on the surface (both surfaces). The organic layer 13 includes at least a light emitting layer. In the present embodiment, the organic layer 13 is configured to include a hole transport layer 131, a light emitting layer 132, and an electron transport layer 133. Such an organic layer 13 has concavities and convexities (unevenness formed so as to maintain the shape of the first concavity and convexity) on both surfaces thereof. Therefore, each layer of the hole transport layer 131, the light emitting layer 132, and the electron transport layer 133 has an unevenness derived from the shape of the first unevenness on both surfaces (the shape of the first unevenness is maintained. Formed irregularities). In the present invention, any layer constituting the “organic layer” is a layer containing 50% by mass or more (more preferably 80% by mass to 100% by mass) of an organic material (organic compound, organometallic complex, etc.). It is.

  In the organic layer 13, any irregularities formed on the surface of the surface facing the metal electrode of each layer having a thickness of 10 nm or more in the organic layer (more preferably, the metal electrode of each layer of the organic layer It is preferable that the standard deviation of the depth distribution of the unevenness is 15 to 50 nm, preferably 17 to 40 nm, and preferably 18 to 30 nm. More preferably. That is, in each of the hole transport layer 131, the light emitting layer 132, and the electron transport layer 133, irregularities formed on the surface of the surface facing the metal electrode (surface opposite to the surface facing the diffraction grating) ( Hereinafter, in some cases, the unevenness formed on the surface of the hole transport layer 131 facing the metal electrode 14 is referred to as “fourth unevenness” and formed on the surface of the light emitting layer 132 facing the metal electrode 14. The unevenness formed is referred to as “fifth unevenness”, and the unevenness formed on the surface of the surface of the electron transport layer 133 facing the metal electrode 14 is referred to as “sixth unevenness”). σ) is more preferably 15 to 50 nm, further preferably 17 to 40 nm, and particularly preferably 18 to 30 nm. If the standard deviation (σ) of the depth distribution of the fourth to sixth irregularities is less than the lower limit, a sufficient diffraction effect cannot be obtained, and it tends to be difficult to sufficiently improve the light extraction efficiency. On the other hand, when the above upper limit is exceeded, there are many sites with a short anode-cathode distance, and in the resulting device, local electric field concentration, leakage current, etc. are generated and sufficient luminous efficiency is obtained. Tend to become impossible.

Further, in the organic layer 13, any unevenness formed on the surface of the surface facing the metal electrode of each layer having a thickness of 10 nm or more in the organic layer (more preferably, each of the layers of the organic layer described above). Any unevenness formed on the surface of the surface facing the metal electrode), and the change rate of the standard deviation of the unevenness depth distribution with respect to the standard deviation of the depth distribution of the first unevenness is + 15% to −15% ( More preferably + 10% to −10%, and still more preferably + 8% to −8%). That is, the fourth to sixth irregularities formed on the surface of each layer of the hole transport layer 131, the light emitting layer 132, and the electron transport layer 133 facing the metal electrode are respectively the depth distribution of the first irregularities. The change rate of the standard deviation of the depth distribution of the unevenness with respect to the standard deviation of + 15% to −15% (more preferably + 10% to −10%, particularly preferably + 8% to −8%) More preferred. If the rate of change exceeds the upper limit, local electric field concentration tends to occur, and leakage current and device deterioration tend to occur. In addition, the element tends to deteriorate and the diffraction effect due to the unevenness tends to decrease, and the light extraction efficiency tends to decrease. In addition, such a change rate has the following formula:
[Change rate] = {([Standard deviation of depth distribution of unevenness (any of fourth to sixth unevenness)] − [Standard deviation of depth distribution of first unevenness]) / [First Standard deviation of depth distribution of concavity and convexity]} × 100
Can be calculated. Moreover, it is preferable that the suitable range of the average height and average pitch of the fourth to sixth irregularities is the same range from the same viewpoint as the preferred range of the average height and average pitch of the first irregularities. . Further, as the fourth to sixth irregularities, it is preferable that the average value (m) of the irregularity depth distribution and the kurtosis (k) of the irregularities satisfy the same condition as the first irregularities, and the inequality ( It is preferable to satisfy 1).

  Note that the unevenness characteristics of each layer in the organic layer are such that after each layer is formed, the unevenness of each layer is changed to the unevenness characteristics of the diffraction grating 11 (characteristics such as the standard deviation (σ) of the unevenness depth distribution). It can obtain | require by employ | adopting and measuring the method similar to this measuring method.

  Moreover, in this invention, it is preferable that the material which comprises the said organic layer is an organic material whose glass transition temperature is 70 to 300 degreeC. Here, the “material constituting the organic layer” means that when the light emitting layer is a layer containing a host material and a dopant material (for example, a phosphorescent material or a fluorescent material), the light emitting layer excluding the dopant material is formed. A material composed of a material (host material) and a material forming another layer of the organic layer, and a material other than the dopant material in the organic layer. That is, in the present embodiment, organic materials constituting each of the hole transport layer 131, the light emitting layer 132, and the electron transport layer 133 (in the case where the light emitting layer is a layer containing a host material and a dopant material, hole transport is performed). The material constituting the layer 131, the material (host material) other than the dopant material constituting the light emitting layer 132, and the material constituting the electron transport layer 133) are all organic having a glass transition temperature (Tg) of 70 ° C. to 300 ° C. A material is preferred. In addition, the value measured by DSC (Differential Scanning Calorimeter) can be employ | adopted as "glass transition temperature" of the material here. In addition, when the glass transition temperature of each layer of the organic layer other than the dopant material is less than the lower limit, the fourth to sixth irregularities are respectively in the numerical ranges as described above when the layers are stacked by the vapor deposition method. The standard deviation (σ) and the rate of change of the standard deviation tend to be difficult.On the other hand, when the upper limit is exceeded, when each layer is laminated by a physical deposition method such as a vapor deposition method, There is a tendency that a boat on which a hole transport material or a light emitting material is placed is deteriorated due to heat at a temperature for vapor deposition of the material, or that a load on the boat is increased and the life of the boat is shortened. That is, as described above, by using an organic material having a glass transition temperature (Tg) of 70 ° C. to 300 ° C. as a material constituting the organic layer (a material other than the dopant material in the organic layer), the fourth Each of the sixth to sixth irregularities can be more easily formed into irregularities having the standard deviation and the standard deviation rate in the numerical range as described above. And by making the fourth to sixth irregularities into irregularities having the standard deviation and the standard deviation of the numerical ranges as described above, local electric field concentration can be more efficiently suppressed, It is possible to sufficiently suppress the occurrence of a phenomenon (roll-off phenomenon) in which the light emission efficiency is reduced in a strong electric field region and the occurrence of a short circuit. In addition, it is also possible to achieve a reduction in device lifetime due to more effective suppression of local electric field concentration. Note that with respect to the light-emitting layer 132, the dopant material may have a small molecular weight depending on the type of the material, and measurement of the glass transition temperature (Tg) may be difficult, or the uneven structure of the light-emitting layer 132 mainly disperses the dopant material. The host material may be an organic material having at least the glass transition temperature (Tg) in the above range, and the Tg of the dopant material may be changed. If it is measurable, the Tg of the dopant material is more preferably within the temperature range.

  Note that a material for forming the organic layer (in the case where the light-emitting layer includes a dopant material, a material other than the dopant material in the organic layer: for example, a material that forms the hole transport layer 131 and a light-emitting layer 132 is formed. By setting the material other than the dopant material (host material) and the material constituting the electron transport layer 133 to an organic material having a glass transition temperature (Tg) of 70 ° C. to 300 ° C., the standard in the above range. The reason why it becomes possible to more efficiently form the unevenness having the change rate of the deviation (σ) and the standard deviation, thereby sufficiently suppressing the occurrence of the roll-off phenomenon and the occurrence of the short-circuit is not necessarily clear. Although not present, the present inventors infer as follows. That is, first, when each layer in the organic layer is laminated by a known physical deposition method such as a vapor deposition method or a sputtering method, it is known that a substance flying on the substrate diffuses on the substrate surface. When a material having a glass transition temperature (Tg) lower than 70 ° C. is used in such a physical deposition method, the time until the material is solidified and fixed after the material arrives on the layered product. It will be relatively long. In this way, when a material having a glass transition temperature (Tg) lower than 70 ° C. is used, it takes time to lose energy, and a state in which fluidity is maintained for a long time after the material arrives on the laminate is maintained. Is done. Therefore, when a material having a glass transition temperature (Tg) lower than 70 ° C. is used, the material is diffused for a longer distance from the arrival position on the stack. The material adhering to the laminate in such a state that it can move over a long distance easily moves and accumulates in the recesses under the influence of the surface tension, and the uneven shape is thereby easily smoothed (leveled). End up. Therefore, when a material having a glass transition temperature (Tg) lower than 70 ° C. is used, it is difficult to stack the organic layer while sufficiently maintaining the shape of the first unevenness. In addition, when the uneven shape is smoothed (leveled), the unevenness is reduced in the layer, the depth of the concave portion becomes shallow, and the thickness of the concave portion becomes thick, so the film thickness becomes uneven. In the obtained organic EL element, the electric field strength is distributed in the organic layer. Therefore, when the uneven shape is smoothed (leveled), a local electric field concentration occurs, and a roll-off phenomenon in which the light emission efficiency decreases in a strong electric field region (in a phosphorescent system) occurs inside the device, and the extraction efficiency decreases. At the same time, a short circuit is likely to occur. In addition, in an organic EL element using a plurality of constituent materials for the organic layer, unstable current flow at the boundary surface of each layer causes a long life. If the thickness of the layer becomes shallow and the film thickness becomes non-uniform, electric field concentration or short-circuiting occurs and the current flow becomes unstable, so that the device life tends to be shortened. In addition, in the organic layer, when the uneven shape is smoothed and the uneven shape becomes dull (the depth of the uneven shape becomes shallow), and the followability to the first uneven shape is reduced, the diffraction effect is also reduced, Light extraction efficiency cannot be obtained.

  On the other hand, by using an organic material having a glass transition temperature (Tg) of 70 ° C. or higher as a material (material other than the dopant material) constituting the organic layer, a layer using a physical deposition method such as an evaporation method is used. When the material is laminated, the material can be fixed in a shorter time after the material arrives on the object to be laminated, thereby maintaining the shape of the first unevenness more sufficiently (followability is sufficiently high) In the state), each layer in the organic layer can be laminated. That is, by using an organic material having a glass transition temperature (Tg) of 70 ° C. to 300 ° C. as a material constituting the organic layer other than at least the dopant material, irregularities (fourth to sixth irregularities) formed in the organic layer ) Can be more easily formed into irregularities having the standard deviation (σ) in the above-described range and the rate of change of the standard deviation. As described above, an organic material having a glass transition temperature (Tg) of 70 ° C. to 300 ° C. is used as a material constituting the organic layer (a material other than the dopant material when the light emitting layer 132 contains the dopant material). Thus, the unevenness (fourth to sixth unevenness) formed in the organic layer has a standard deviation in the range of 15 to 50 nm and is + 15% to −15% with respect to the standard deviation of the first unevenness Therefore, it is possible to form a concavo-convex having high followability with respect to the first concavo-convex. In addition, regarding the material of the organic layer, the expression “other than the dopant material” described above is not an expression intended to use a dopant material whose glass transition temperature (Tg) is not within the above temperature range. Depending on the type of material, some materials have a small molecular weight and it is difficult to measure the glass transition temperature (Tg). The light-emitting layer 132 itself has a concavo-convex structure mainly composed of “host material (dopant material). When the dopant material and the host material are included in the material of the light emitting layer, at least the host material has a glass transition temperature (Tg) in the above range. This means that any organic material can be used. Therefore, when the Tg of the dopant material can be measured, the dopant material is preferably a material having a glass transition temperature (Tg) within the temperature range (70 ° C. to 300 ° C.). And when the organic material whose glass transition temperature (Tg) is 70 to 300 degreeC is utilized for the material of organic layers other than dopant material at least, the unevenness | corrugation depth does not become locally shallow, but 1st unevenness | corrugation Since it becomes possible to form an organic layer that sufficiently maintains the concavo-convex structure and a sufficient diffraction effect can be obtained, the light extraction efficiency can be sufficiently improved. Further, by forming unevenness having high followability with respect to the first unevenness, electric field concentration can be sufficiently suppressed, and thereby occurrence of roll-off phenomenon and occurrence of short circuit can be sufficiently suppressed. Therefore, by using a material having a glass transition temperature (Tg) of 70 ° C. to 300 ° C. as the material of the organic layer, it is possible to achieve a sufficiently high luminous efficiency and an element caused by electric field concentration. The present inventors infer that the deterioration of the element can be prevented and the life of the element can be extended.

  In addition, a material constituting the organic layer (a material constituting each of the hole transport layer 131, the light emitting layer 132, and the electron transport layer 133 and when the light emitting layer 132 contains a dopant material, other than the dopant material) The lower limit value of the suitable temperature range (70 ° C. to 300 ° C.) of the glass transition temperature (Tg) of the material (No. 90) is 90 from the viewpoint that a layer having higher followability to the shape of the first unevenness can be formed. More preferably, it is 110 degreeC, and it is especially preferable that it is 110 degreeC. Moreover, the suitable temperature range (Tg) of the glass transition temperature (Tg) of the material which comprises each layer of the said organic layer (When light emitting layer 132 contains dopant material, material other than the dopant material which comprises each layer of an organic layer.) As an upper limit of 70 ° C. to 300 ° C., the temperature condition during vapor deposition can be made more gentle, power consumption during device manufacture can be suppressed, and material decomposition (breakdown of chemical bonds of organic matter) From the viewpoint of reducing the concern, it is more preferably 200 ° C., and particularly preferably 160 ° C.

  Examples of the material constituting the hole transport layer 131 include phthalocyanine derivatives, naphthalocyanine derivatives, porphyrin derivatives, N, N′-bis (3-methylphenyl)-(1,1′-biphenyl) -4,4 ′. -Aromatic diamine compounds such as diamine (TPD) and 4,4′-bis [N- (naphthyl) -N-phenyl-amino] biphenyl (α-NPD), oxazole, oxadiazole, triazole, imidazole, imidazolone, Examples include stilbene derivatives, pyrazoline derivatives, tetrahydroimidazole, polyarylalkanes, butadiene, 4,4 ′, 4 ″ -tris (N- (3-methylphenyl) N-phenylamino) triphenylamine (m-MTDATA). In particular, a suitable temperature range of the glass transition temperature (Tg) described above An organic material to be filled is preferable. Α-NPD (Tg: 95 ° C.), TCTA (Tg: 149 ° C.), 2-TANTA (Tg: 110 ° C.), m-MTDATA (Tg: 75 ° C.), SpiroTPD (Tg: 115) ° C), TAPB (Tg: 113 ° C), a trinaphthylbenzene derivative, and the like can be suitably used.

  Further, as a material constituting such a hole transport layer 131, it is preferable to use a material similar to a host material of the light emitting layer 132 described later. Thus, when the material of the hole transport layer 131 and the host material of the light emitting layer 132 are the same material, the interface between the hole transport layer and the light emitting layer is substantially eliminated, and the energy barrier and interface A decrease in efficiency due to a decrease in carrier mobility can be suppressed.

  Further, the thickness of the hole transport layer 131 is preferably 5 to 200 nm, and more preferably 10 to 100 nm. If the thickness is less than the lower limit, it is difficult to obtain a uniform film, in-plane distribution occurs in the hole mobility in the device, local current concentration occurs, and the life is shortened. On the other hand, when the upper limit is exceeded, the element resistance increases, the power efficiency tends to decrease, and the manufacturing time becomes longer.

Furthermore, the light emitting layer 132 is provided to recombine the holes injected from the transparent electrode 11 and the electrons injected from the metal electrode 15 to emit light. Materials used to form such a light emitting layer include anthracene, naphthalene, pyrene, tetracene, coronene, perylene, phthaloperylene, naphthaloperylene, diphenylbutadiene, tetraphenylbutadiene, coumarin, oxadiazole, bisbenzoxazoline, Organometallic complexes such as bisstyryl, cyclopentadiene, aluminum quinolinol complex (Alq ₃ ), tri- (p-terphenyl-4-yl) amine, 1-aryl-2,5-di (2-thienyl) pyrrole derivative, pyran Quinacridone, rubrene, distyrylbenzene derivatives, distyrylarylene derivatives, distyrylamine derivatives, various fluorescent dyes, and the like can be used. In addition, as a material used for the light emitting layer 132, a light emitting material selected from the above-described compounds may be appropriately mixed and used. The light-emitting layer may have a structure including a so-called host material and a dopant material (a light-emitting material (such as a phosphorescent material or a fluorescent dye) described above) introduced into the host material. In this way, by doping a light-emitting material as described above as a dopant material (guest material) in a host material having high carrier mobility, a dipole-dipole interaction (Forster mechanism), an electron exchange interaction It is also possible to emit light using (Dexter mechanism).

In addition, as such a dopant material, it is preferable to use a phosphorescent material because it is possible to significantly improve the light emission efficiency. In other words, when a phosphorescent material is used as a dopant material, all singlet excitons are crossed by inter-units due to internal heavy atom effects and the emission transition probability of triplet excitons is sufficiently high. Thus, since all singlet excitons and triplet excitons generated by electrical excitation can be used for light emission, the light emission efficiency tends to be greatly improved. The “phosphorescent material” herein may be any material that emits light from a spin multiplet (a phosphorescent material that generates phosphorescence), and is known in the art, for example, an organometallic complex having a heavy metal as a central metal. A phosphorescent material can be used as appropriate. Moreover, as such a phosphorescence-emitting material, what contains heavy metals, such as iridium, is preferable, for example, Ir (ppy) ₃ etc. can be used suitably. As such a dopant material (phosphorescent material or the like), when the glass transition temperature (Tg) can be measured, a suitable temperature range of the glass transition temperature (Tg) of the dopant material is a dopant material constituting the organic layer. It is preferable that it is the same range from the same viewpoint as the suitable temperature range of glass transition temperature (Tg) of materials other than this.

  Moreover, as a constituent material (host material) of the light emitting layer 132 for dispersing the dopant material (guest material) that can be contained in the light emitting layer 132, an organic layer having a sufficiently high conformity to the shape of the first unevenness is used. From the viewpoint of obtaining, a material satisfying a suitable temperature range of the above-mentioned glass transition temperature (Tg) is preferable. For example, TCTA (Tg: 149 ° C.), TPBi (Tg: 124 ° C.), 2-TANTA (Tg: 110 ° C.) ), M-MTDATA (Tg: 75 ° C.), spiroTPD (Tg: 115 ° C.), TAPB (Tg: 113 ° C.), a trinaphthylbenzene derivative, and the like can be preferably used.

  Furthermore, when the light emitting layer 132 contains a host material and a dopant material (guest material), the content of the dopant material in the light emitting layer 132 is preferably 1 to 20% by mass, and 3 to 15% by mass. More preferably. If the content of such a dopant material is less than the lower limit, energy is not efficiently transferred from the host material to the guest material, and the ratio of energy deactivation in the host material tends to increase, whereas, if the upper limit is exceeded, Further, not only is the efficiency lowered due to concentration quenching and triplet triplet annihilation, and furthermore, when the Tg of the dopant material (guest material) is lower than 70 ° C., the uneven structure is easily smoothed (leveled). Therefore, it tends to be difficult to form a light emitting layer having a higher followability of the concavo-convex structure.

  Moreover, as materials (host material etc.) other than the said dopant material for comprising such a light emitting layer, they are organic materials whose glass transition temperature is 100 degreeC-300 degreeC (more preferably 90 degreeC-200 degreeC). It is more preferable. When the glass transition temperature of the organic material constituting such a light emitting layer is within the above range, it is possible to make the light emitting layer a layer having sufficiently high followability with respect to the first unevenness. It becomes. Further, the glass transition temperature of the dopant material preferably satisfies the same conditions as the host material from the same viewpoint.

  Further, the thickness of the light emitting layer 132 is preferably 1 to 80 nm, and more preferably 10 to 50 nm. If the thickness is less than the lower limit, it is difficult to obtain a uniform film, carrier distribution in the element is in-plane distribution, local current concentration occurs, and the life is shortened. On the other hand, when the upper limit is exceeded, the element resistance increases, the power efficiency tends to decrease, and the manufacturing time becomes longer.

Moreover, as a material which comprises the electron carrying layer 133, the material which can form the electron carrying layer 133 can be utilized suitably, for example, a nitro substituted fluorene derivative, a diphenylquinone derivative, a thiopyran dioxide derivative, Examples include heterocyclic tetracarboxylic anhydrides such as naphthaleneperylene, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives, and organometallic complexes such as aluminum quinolinol complexes (Alq ₃ ). Furthermore, in the oxadiazole derivative, a thiadiazole derivative in which the oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and a quinoxaline derivative having a quinoxaline ring known as an electron withdrawing group can also be used as an electron transport material. Furthermore, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used. Among the materials constituting such an electron transport layer 133, from the viewpoint of obtaining an organic layer having a sufficiently high followability to the shape of the first unevenness, a suitable temperature range of the glass transition temperature (Tg) described above is set. An organic material to be filled is preferable, and materials such as Alq ₃ (Tg: 175 ° C.), TPBi (Tg: 124 ° C.), and BAlq (Tg: 99 ° C.) can be suitably used.

  Furthermore, the thickness of the electron transport layer 133 is preferably 5 to 200 nm, and more preferably 10 to 100 nm. If the thickness is less than the lower limit, it is difficult to obtain a uniform film, and in-plane distribution occurs in the electron mobility in the device, local current concentration occurs, and the lifetime is shortened. On the other hand, when the upper limit is exceeded, the element resistance increases, the power efficiency tends to decrease, and the manufacturing time becomes longer.

  Further, in the organic layer 13, the followability of the unevenness tends to decrease as the stacking order of each layer progresses, and in a relatively thick layer having a layer thickness of 50 nm or more, smoothing (leveling) is performed at the time of stacking. ), The second layer or more layers (in the present embodiment, the light-emitting layer 132 and the electron transport layer 133) or the layer having a thickness of 50 nm or more in the stacking order of the organic layers. It is preferable that the glass transition temperature of the material for constituting (material other than the dopant material) is 90 ° C. to 300 ° C. (more preferably 100 to 200 ° C.) (in addition, measurement of Tg in the dopant material (phosphorescent material etc.)) If possible, the dopant material preferably satisfies the same conditions.) If such a glass transition temperature is less than the lower limit, it tends to be difficult to achieve a higher degree of conformability of the uneven shape.

  Furthermore, as the organic layer 13, it is preferable that the uniformity of the thickness of each layer is high, and the average value of the thickness between two or more concave portions of each layer (distance between the lowest points of the concave portions) and each layer The average value of the thickness between any two or more convex portions (the distance between the vertices of the convex portions formed on the surface facing the metal electrode of each layer) is used as an ultra-thin slice of an organic EL element (as a measurement sample) The ratio of the thickness between the recesses to the average value of the thickness between the recesses ([the thickness between the recesses] The average value] / [average thickness of protrusions] is more preferably in the range of 0.8 to 1.5 (more preferably 0.9 to 1.4). When such a ratio is outside the above range, the uniformity of the film thickness is low, and it tends to be difficult to sufficiently suppress electric field concentration. The thickness between the concave portions and the thickness between the convex portions will be described with reference to FIG. FIG. 2 is a conceptual diagram schematically showing arbitrary layers 13A and 13B in the organic layer. The layer 13B is a layer obtained by stacking on the layer 13A. In such a layer 13B, the “thickness between the recesses” is such that the lowest point P1 of any recess formed on the surface of the layer 13A on the substrate side facing the metal electrode and the shape of the recess are maintained. The distance X is the distance from the lowest point P2 of the recess on the layer 13B formed. In the layer 13B, the “thickness between the protrusions” is formed so as to maintain the vertex P3 of the arbitrary protrusions formed on the surface of the layer 13A facing the metal electrode and the shape of the protrusions. This is the distance Y between the vertex P4 of the convex portion on the layer 13B.

  In addition, as the organic layer 13, the average value of the thickness between any two or more concave portions of the whole organic layer (distance between the lowest points of the concave portions) and between any two or more convex portions of the whole organic layer When the average value of the thickness (distance between the apexes of the convex portions formed on the surface facing the metal electrode of each layer) is measured from a transmission electron microscopic image of an ultra-thin slice of the organic EL element, the convex portions The ratio of the average thickness between the recesses to the average thickness between the recesses ([average thickness between recesses] / [average thickness between the recesses]) is in the range of 0.8 to 1.5. More preferably. When such a ratio is out of the above range, it cannot be said that the film thickness uniformity of the entire organic layer is sufficient, and it tends to be difficult to sufficiently suppress electric field concentration.

<Metal electrode 14>
The metal electrode 14 is laminated on the diffraction grating so that the shape of the first unevenness is maintained, and at least the surface of the metal electrode 14 on the organic layer side (the surface facing the first unevenness). ) Is formed with unevenness derived from the shape of the first unevenness.

  In such a metal electrode 14, the unevenness (second unevenness) formed on the surface of the surface facing the organic layer has a standard deviation (σ) of the unevenness depth distribution of 15 to 50 nm. . In addition, the standard deviation (σ) of the depth distribution of the second unevenness is more preferably 17 to 40 nm, and further preferably 18 to 30 nm. If the standard deviation (σ) of the depth distribution of the second unevenness is less than the lower limit, a sufficient diffraction effect cannot be obtained, and it becomes difficult to sufficiently improve the light extraction efficiency. On the other hand, if the above upper limit is exceeded, there will be many sites with a short anode-cathode distance, and in the resulting device, local electric field concentration, leakage current, etc. may occur and sufficient luminous efficiency can be obtained. become unable.

The rate of change of the standard deviation of the second unevenness depth distribution with respect to the standard deviation of the first unevenness depth distribution is + 15% to −15% (condition (C)). When the rate of change exceeds 15%, local electric field concentration occurs, and leakage current and device deterioration occur and become cheaper. On the other hand, when the change rate is less than −15%, local electric field concentration occurs, and leakage current and device elements are reduced. Deterioration is likely to occur, and the diffraction effect due to the unevenness is reduced, so that the light extraction efficiency is reduced. The rate of change of the standard deviation of the second unevenness depth distribution is more preferably + 10% to −10%, and further preferably + 8% to −8% from the same viewpoint. In addition, such a change rate has the following formula:
[Change rate] = {([Standard deviation of depth distribution of second unevenness] − [Standard deviation of depth distribution of first unevenness]) / [Standard deviation of depth distribution of first unevenness]} × 100
Can be calculated.

  In addition, in the metal electrode 14, the suitable range of the average value of the depth distribution of the 2nd unevenness | corrugation, average height, and average pitch is the viewpoint similar to the suitable range of the 1st unevenness | corrugation average height and average pitch. The same range is preferable. Further, as the second unevenness, it is preferable that the kurtosis of the unevenness satisfies the same condition as the first unevenness, and it is preferable that the inequality (1) is satisfied. The unevenness (second unevenness) characteristic (for example, the depth distribution of the unevenness) formed on the surface of the surface of the metal electrode 14 facing the organic layer is only the metal electrode 14 from the organic EL element. The unevenness formed on the surface (peeling surface) opposite the organic layer of the peeled metal electrode is physically separated from the unevenness characteristic of the diffraction grating 11 (standard deviation of the depth distribution of the unevenness). It can be determined by adopting the same method as the measuring method of (characteristic such as (σ)). In addition, as a method of peeling only the metal electrode 14 from the organic EL element, an adhesive tape (for example, “Scotch Mending Adhesive Tape” manufactured by Sumitomo 3M Co., Ltd.) is used on the outer surface of the metal electrode of the obtained organic EL element. After affixing, it is preferable to employ a method in which only the metal electrode is peeled off from the organic layer using the adhesive tape under the atmosphere and room temperature (25 ° C.) conditions. Moreover, the method of peeling only a metal electrode from an organic EL element using an adhesive tape is described in, for example, Formation and growth of black spots in organic light-emitting diodes, Journal of Applied Physics, Vol. 80, 6002 to 6007 (1996) and the like, which is a known method, and the conditions for peeling only the metal electrode may be appropriately changed according to the material of the metal electrode. Thus, in this invention, the characteristic of the unevenness | corrugation formed in the surface of the surface which opposes the organic layer of the metal electrode 14 sticks an adhesive tape on the outer surface of the metal electrode of an organic EL element, Then, the adhesive tape Measures by peeling only the metal electrode from the organic layer by using, and analyzing the unevenness of the surface of the metal electrode on the adhesive tape with an atomic force microscope to obtain an unevenness analysis image (SPM image) You can also. Alternatively, the metal electrode surface and a flexible film may be attached with an adhesive, and only the metal electrode may be peeled from the organic layer.

  The material for the metal electrode 14 is not particularly limited as long as it is a material for forming the metal electrode of the organic EL element, but a substance having a small work function can be preferably used. Examples of the material of the metal electrode 14 include aluminum, MgAg, MgIn, and AlLi. As described above, since the material of the metal electrode 14 is made of a metal or a metal compound, first, in the case of stacking by a known physical deposition method such as a vapor deposition method or a sputtering method, the material is formed on the layer to be stacked as compared with the organic material. Energy is lost in a shorter time, and the material is solidified and fixed at or near the arrival position so that the film thickness becomes uniform by a known method such as vapor deposition or sputtering. By laminating, it is possible to form unevenness with sufficiently high followability to the unevenness of the surface formed on the stack. Thus, since the metal electrode 14 can form irregularities with sufficiently high followability with respect to the irregularities formed in the layer in contact with the electrode, the irregularities of the metal electrode 14 are In the case where (C) is satisfied, the unevenness of the layer in contact therewith is highly likely to be an unevenness that satisfies the conditions described in the conditions (B) and (C), and the uniformity of the film thickness is sufficient in each layer. It can be seen that a high organic EL element is obtained.

  Moreover, as thickness of the metal electrode 14, it is preferable that it is 5-200 nm, and it is preferable that it is 10-100 nm. If the thickness is less than the lower limit, it is difficult to obtain a uniform film, and local electric field concentration occurs, the light absorption rate increases, and as a result, the extraction efficiency tends to decrease or the conductivity tends to decrease. On the other hand, if the upper limit is exceeded, problems such as damage to the organic layer due to radiant heat during electrode formation occur, and the manufacturing time also increases.

  Thus, in the organic EL element of the present invention, the diffraction grating 11 satisfies the above condition (A), and the first unevenness and the second unevenness both have an uneven shape. Satisfying the condition (B) that the standard deviation of the unevenness distribution of the unevenness obtained based on the unevenness analysis image obtained by analyzing using the above is 15 to 50 nm, and the depth distribution of the first unevenness The condition (C) that the rate of change of the standard deviation of the depth distribution of the second unevenness with respect to the standard deviation is + 15% to −15% is satisfied. By satisfying such a condition (A), a sufficient diffraction effect can be obtained by the diffraction grating. Further, by satisfying such conditions (B) and (C), the film thickness of each layer in the element becomes uniform, and a sufficiently high diffraction effect derived from the first unevenness is obtained while locally. Therefore, it is possible to sufficiently suppress the occurrence of electric field concentration and leakage current, so that the light extraction efficiency can be sufficiently stably improved. In the organic EL device of the present invention, local electric field concentration can be sufficiently suppressed. Therefore, even when the device is a phosphorescent device, the triplet excited state of the phosphorescent material disappears due to electric field concentration. Thus, the occurrence of a so-called roll-off phenomenon can be sufficiently suppressed, and thereby a decrease in the phosphorescence efficiency can also be sufficiently suppressed.

<Optical member 15>
The optical member 15 is used to efficiently extract light that repeatedly reflects in the transparent support substrate to the outside. Such an optical member 15 is not particularly limited as long as it can be used for extracting light from the organic EL element, and has a structure capable of extracting light to the outside of the element. A known optical member can be used as appropriate. As such an optical member 15, for example, a method similar to a method of manufacturing a lens member (convex lens (hemispherical lens or the like), concave lens, prism lens, cylindrical lens, diffraction grating 11 (uneven layer) described later) is adopted. A microlens made of a concavo-convex layer that can be formed by the above method), a diffusion sheet in which a diffusing material is kneaded into a transparent body, a diffusing plate, or the like may be used. Further, as such an optical member 15, it is preferable to use a lens member because light can be extracted more efficiently. Further, as such an optical member 15, a plurality of lens members may be used. In this case, so-called micro lenses may be formed by arranging fine lens members. A commercially available product may be used as appropriate as the optical member 15 for extracting such light to the outside.

Further, when a microlens composed of a concavo-convex layer that can be formed by adopting the same method as the method of manufacturing the diffraction grating 11 (concavo-convex layer) is used as the optical member 15, the shape of the concavo-convex is atomic. When the unevenness analysis image obtained by analyzing with an atomic force microscope is subjected to a two-dimensional fast Fourier transform process to obtain a Fourier transform image, the Fourier transform image has an approximate origin at which the absolute value of the wave number is 0 μm ^−1. A shape showing a circular or annular pattern as a center is preferable. In the microlens composed of such a concavo-convex layer, the concavo-convex shape is isotropic when viewed from all cross-sectional directions, light is incident from one side (surface in contact with the substrate) side, When light is emitted from the surface on which the shape is formed, the angle dependency (luminance angle dependency) and chromaticity change of the emitted light can be sufficiently reduced.

Further, when the microlens composed of the concavo-convex layer as described above is used as the optical member 15, the Fourier transform image of the concavo-convex exists in a region where the absolute value of the wave number is in the range of 1 μm ⁻¹ or less. Preferably there is. When such a Fourier transform image shows the above-mentioned conditions, it becomes possible to sufficiently reduce the angle dependency and chromaticity change of the emitted light at a higher level. Moreover, as such a circular or annular pattern of the Fourier transform image, the absolute value of the wave number is 0.05 to from the viewpoint of efficiently refracting or diffracting the emission spectrum in the visible region (380 nm to 780 nm). preferably present in a region to be a range of 1 [mu] m ^-1, and more preferably the absolute value of the wave is present in the region to be a range of 0.1 to 0.5 [mu] m ^-1. When the circular or annular pattern does not exist in the region within the range of the absolute value of the wave number, that is, within the range among the bright spots of the Fourier transform image constituting the circular and annular pattern. When the number of bright spots existing in the lens is less than 30%, there is a tendency that effective refraction as a lens for extracting light cannot be obtained. Moreover, as a pattern of such a Fourier-transform image, it is more preferable that it is a cyclic | annular form from a viewpoint of obtaining sufficient effect with respect to the light of the wavelength which exists in a visible region (380 nm-780 nm).

  Moreover, when using the microlens which consists of the above uneven | corrugated layers as the optical member 15, it is preferable that the average pitch of the unevenness | corrugation of a microlens is the range of 2-10 micrometers, and is the range of 2.5-5 micrometers. Is more preferable. If the average pitch of such irregularities is less than the lower limit, the diffraction effect as a diffraction grating becomes stronger than the refraction effect for taking out the light of the optical member to the outside, and not only the light extraction effect is lowered, but also the output effect is reduced. Depending on the measurement position, the angle dependency of the incident light tends to be high, and there is a tendency that sufficient emission cannot be obtained. There is a tendency. Furthermore, the average height of the unevenness of such a microlens is preferably in the range of 400 to 1000 nm, more preferably in the range of 600 to 1000 nm, and still more preferably in the range of 700 to 900 nm. If the average height (depth) of such irregularities is less than the lower limit, sufficient refraction or diffraction effects tend not to be obtained. On the other hand, when the upper limit is exceeded, the mechanical strength decreases, Cracks tend to occur during use. In addition, the microlens composed of such a concavo-convex layer adopts a method for manufacturing the diffraction grating 11 described later, and appropriately changes conditions and the like when forming the matrix so that the characteristics (size, etc.) of the concavo-convex shape are obtained. It can be formed by adjusting appropriately.

  Further, as the optical member 15 for taking out such light to the outside, various sizes and shapes can be used as appropriate according to the use, size, configuration, etc. of the organic EL element. From the viewpoint of suppressing reflection at the interface, a microlens made of a concavo-convex layer that can be formed by employing a method similar to the method of manufacturing a hemispherical lens and a diffraction grating 11 (concave / convex layer) to be described later is used. Further, the thickness of the organic EL element is not regarded as important (when the thickness may be large, it is preferable to use a hemispherical lens, and when the thickness is regarded as important (thin is preferred), the unevenness is It is preferable to use a microlens composed of a layer, and thus a microlens composed of a concavo-convex layer obtained by adopting a method similar to the method of manufacturing the diffraction grating 11 (concavo-convex layer). In the case where the shape is used, the uneven shape becomes isotropic when viewed from all cross-sectional directions, and the shape is formed by making light incident from one side (surface in contact with the substrate) side. When light is emitted from the surface, it is possible to sufficiently reduce the angle dependency (luminance angle dependency) and chromaticity change of the emitted light.

  Moreover, as a hemispherical lens suitable as such an optical member 15, a hemispherical lens in which the area of the bottom surface of the hemispherical lens is 1 to 10 times the light emitting area of the organic EL element is preferable. That is, when a hemispherical lens is used, one pixel that is the light emitting area of the organic EL element is used by using a hemispherical lens having a bottom surface area that is 1 to 10 times the area of one pixel that is the light emitting area of the organic EL element. Is preferably completely covered with the bottom surface of the hemispherical lens. When the area of the bottom surface of such a hemispherical lens is less than the lower limit, the light emitted from the organic EL element tends to increase in an incident angle from the oblique direction with respect to the spherical portion of the hemispherical lens. EL elements tend to be too large and hemispherical lenses tend to be expensive.

  In addition, the material of the optical member 15 is not particularly limited, and an optical member made of a known material can be used as appropriate. For example, a transparent inorganic material such as glass, a polyester resin such as polyethylene terephthalate, or a cellulose-based material. Transparent resin materials made of transparent polymers such as resins, acetate resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, acrylic resins, etc. are used as appropriate. I can do it. In addition, such an optical member 15 has an adhesive layer so that air is not caught between the organic EL element and the optical member 15 in order to suppress reflection between the organic EL element and the optical member 15. And it is preferable to be laminated | stacked on the said transparent support substrate 10 through the adhesive bond layer.

  Further, such an optical member 15 is provided on the surface of the optical member (in the case of using a microlens made of an uneven layer as described above as the optical member 15 from the viewpoint of improving the friction resistance and scratch resistance of the surface. A protective layer may be laminated on the surface on which the concavo-convex shape is formed. As such a protective layer, a transparent film or a transparent inorganic vapor deposition layer can be used as appropriate. Such a transparent film is not particularly limited, and a known transparent film can be appropriately used. For example, polyester resins such as polyethylene terephthalate, cellulose resins, acetate resins, polyethersulfone resins, polycarbonates Examples thereof include films made of transparent polymers such as resin, polyamide resin, polyimide resin, polyolefin resin, and acrylic resin. Further, such a transparent film may be used by forming a pressure-sensitive adhesive layer or an adhesive layer on one surface and sticking it on the surface of the optical member (the optical member 15 has the above-described irregularities). When using a microlens composed of layers, a transparent film may be bonded so that a space is formed between the convex portions. Examples of such pressure-sensitive adhesives or adhesives include acrylic pressure-sensitive adhesives, ethylene-vinyl acetate copolymers, natural rubber-based pressure-sensitive adhesives, polyisobutylene, butyl rubber, styrene-butylene-styrene copolymers, and styrene-imprene- Synthetic rubber adhesives such as styrene block copolymers, polyurethane adhesives, and polyester adhesives may be used as appropriate.

Moreover, when laminating an inorganic vapor deposition layer as the protective layer, a known metal material capable of forming a transparent inorganic layer by vapor deposition can be used as appropriate, for example, Sn, In, Te, Examples thereof include oxides, nitrides, and sulfides of metals such as Ti, Fe, Co, Zn, Ge, Pb, Cd, Bi, Se, Ga, and Rb. As such a metal material, TiO ₂ can be preferably used from the viewpoint that deterioration due to oxidation can be sufficiently prevented, and ZnS is preferably used from the viewpoint that low luminance and high luminance can be obtained. Can be used. Moreover, it does not restrict | limit especially as a method of forming such an inorganic vapor deposition layer, What is necessary is just to manufacture suitably using a well-known physical vapor deposition apparatus.

  In the organic EL device of the present invention, the thickness in the transparent electrode and the organic layer (in the embodiment shown in FIG. 1, the hole transport layer, the light emitting layer, and the electron transport layer) is 10 nm or more. All of the irregularities formed on the surface of the surface facing the metal electrode in each layer (more preferably, the surface of the surface of the organic layer facing the metal electrode is formed on the surface of the organic layer. The standard deviation of the depth distribution of the unevenness is 15 to 50 nm (more preferably 17 to 40 nm, still more preferably 18 to 30 nm), and the depth of the first unevenness. The rate of change of the standard deviation of the uneven depth distribution with respect to the standard deviation of the distribution is + 15% to −15% (more preferably + 10% to −10%, still more preferably + 10% to −10%). Preferred. As described above, all the layers of the transparent electrode and the organic layer having a thickness of 10 nm or more (more preferably, the transparent electrode and the organic layer (the hole transport layer, the light emitting layer) And the unevenness of each layer) of the electron transport layer) is such that the standard deviation of the unevenness depth distribution is 15 to 50 nm, and the unevenness with respect to the standard deviation of the depth distribution of the first unevenness When the rate of change of the standard deviation of the depth distribution is + 15% to -15%, the uniformity of the film thickness between each layer becomes higher, and the occurrence of electric field concentration and leakage current is suppressed at a higher level. can do.

  Next, a method that can be suitably used as a method for manufacturing the organic EL element of the embodiment shown in FIG. 1 will be described. As a method for manufacturing such an organic EL element, a step of forming a diffraction grating on one surface side of a transparent support substrate (diffraction grating forming step), the transparent electrode on the surface of the diffraction grating, A step of obtaining an organic EL element by laminating the organic layer and the metal electrode so as to maintain the shape of the first unevenness formed on the surface of the diffraction grating (unevenness layer) (organic EL) A method including an element forming step) and a step of placing an optical member on the surface opposite to the surface on which the diffraction grating of the transparent support substrate is placed (optical member placement step) can be employed. Hereinafter, the diffraction grating forming process, the organic EL element forming process, and the optical member arranging process will be described separately.

(Diffraction grating forming process)
The method for manufacturing such a diffraction grating 11 is not particularly limited, and is a known method (for example, International Publication No. 2011/007878 ( The method described in WO2011 / 007878A1) and the like can be used as appropriate.

  Moreover, as a method for manufacturing such a diffraction grating 11, since the 1st unevenness | corrugation can be formed more efficiently, the material (diffraction for forming the diffraction grating 11 (irregularity layer) on a transparent support substrate is used. (Grating forming material) is applied, the diffraction grating forming material is cured while pressing the forming die for forming the diffraction grating, and then the mother die is removed to form a layer with irregularities formed on the transparent support substrate. It is preferable to use a method including a step of laminating. In addition, according to such a method, it becomes possible to manufacture efficiently the diffraction grating in which the unevenness | corrugation which satisfy | fills the characteristic of the above-mentioned 1st unevenness | corrugation was formed. Hereinafter, a method for manufacturing such a diffraction grating 11 will be described.

  A method for manufacturing such a diffraction grating 11 is a method using a matrix (mold) for forming a diffraction grating. As such a matrix for forming a diffraction grating (mold), it is cured by pressing it against a layer made of an uncured diffraction grating forming material, thereby transferring the shape of the irregularities formed on the matrix ( The diffraction grating (unevenness layer) on which the first unevenness described in the diffraction grating 11 described above is formed can be used. Therefore, such a matrix (mold) for forming a diffraction grating has a surface with a concavo-convex shape, and the characteristics of the concavo-convex shape (average height, average pitch, etc.) are on the surface of the diffraction grating 11 described above. It is preferable that it has the same characteristic as the unevenness | corrugation currently formed.

  In addition, the method for producing such a matrix for forming a diffraction grating (mold) is not particularly limited. For example, a block copolymer composed of first and second polymers (segments) is formed on the surface of a base material. A step (I) of applying a block copolymer solution containing a solvent, a step (II) of drying the coating film on the substrate, and the dried coating film having a glass transition temperature equal to or higher than the glass transition temperature of the block copolymer. Step (III) of heating at a temperature of (5) and Step (IV) of forming a concavo-convex structure on the substrate by removing the second polymer (segment) by etching the coating film after performing the step (III) And (V) heating the concavo-convex structure at a temperature equal to or higher than the glass transition temperature of the first polymer (segment), and forming a seed layer on the concavo-convex structure after the step (V) is applied. (VI) and a power supply on the seed layer. By a step of laminating a metal layer (VII), the method can be suitably used and a step (VIII) of peeling the substrate having the uneven structure of the metal layer and the seed layer. Hereinafter, steps (I) to (VIII) will be described separately with reference to the drawings.

<Process (I)>
Step (I) is a step of applying a block copolymer solution containing a block copolymer composed of first and second polymers (segments) and a solvent to the surface of the substrate.

As such a block copolymer, a copolymer having a first polymer segment composed of a first homopolymer and a second polymer segment composed of a second homopolymer different from the first homopolymer. Is used. Such a second homopolymer preferably has a solubility parameter that is 0.1 to 10 (cal / cm ³ ) ^1/2 higher than the solubility parameter of the first homopolymer. When the difference between the solubility parameters of the first and second homopolymers is less than 0.1 (cal / cm ³ ) ^1/2 , it becomes difficult to form a regular microphase separation structure of the block copolymer. On the other hand, when the difference exceeds 10 (cal / cm ³ ) ^1/2 , it is difficult to prepare a uniform solution of the block copolymer.

  Examples of the monomer that can be used as the raw material for the first homopolymer and the second homopolymer include styrene, methylstyrene, propylstyrene, butylstyrene, hexylstyrene, octylstyrene, and methoxystyrene. , Ethylene, propylene, butene, hexene, acrylonitrile, acrylamide, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, hexyl methacrylate, octyl methacrylate, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, hexyl acrylate, octyl acrylate, methacryl Acid, acrylic acid, hydroxyethyl methacrylate, hydroxyethyl acrylate, Ren'okishido, propylene oxide, dimethyl siloxane, lactic acid, vinyl pyridine, hydroxystyrene, styrene sulfonate, isoprene, butadiene, epsilon-caprolactone, isopropylacrylamide, vinyl chloride, ethylene terephthalate, tetrafluoroethylene, vinyl alcohol. Among these, it is preferable to use styrene, methyl methacrylate, ethylene oxide, butadiene, isoprene, vinyl pyridine, and lactic acid from the viewpoint that phase-separation formation easily occurs and unevenness is easily formed by etching.

  The combination of the first homopolymer and the second homopolymer includes styrene-based polymer (more preferably polystyrene), polyalkyl methacrylate (more preferably polymethyl methacrylate), polyethylene oxide, polybutadiene, polyisoprene, and polyvinylpyridine. And two combinations selected from the group consisting of polylactic acid. Among these combinations, from the viewpoint that the depth of the irregularities formed on the block copolymer can be further increased by preferentially removing one of the homopolymers by etching treatment, styrenic polymer and poly More preferred are combinations of alkyl methacrylates, combinations of styrenic polymers and polyethylene oxide, combinations of styrenic polymers and polyisoprene, combinations of styrenic polymers and polybutadiene, combinations of styrenic polymers and polymethyl methacrylate, styrenic polymers and polyisoprene. The combination of styrene polymer and polybutadiene is particularly preferred. More preferably, it is a combination of polystyrene (PS) and polymethyl methacrylate (PMMA).

  The number average molecular weight (Mn) of the block copolymer is preferably 500,000 or more, more preferably 1,000,000 or more, and particularly preferably 1,000,000 to 5,000,000. When the number average molecular weight is less than 500,000, the average pitch of the unevenness formed by the microphase separation structure of the block copolymer becomes small, and the average pitch of the unevenness of the obtained diffraction grating becomes insufficient. In particular, when it is necessary to diffract the illumination light over the visible wavelength range, the average pitch is preferably 10 to 700 nm. From this point, the number average molecular weight (Mn) of the block copolymer is 500,000 or more. Preferably there is. On the other hand, when the block copolymer having a number average molecular weight (Mn) of 500,000 or more is used, it is difficult to obtain a desired uneven pattern by electroforming unless the second heating step is performed after the etching step. There is a tendency.

  The molecular weight distribution (Mw / Mn) of the block copolymer is preferably 1.5 or less, and more preferably 1.0 to 1.35. When such molecular weight distribution exceeds 1.5, it becomes difficult to form a regular microphase separation structure of the block copolymer. The number average molecular weight (Mn) and the weight average molecular weight (Mw) of the block copolymer are values measured by gel permeation chromatography (GPC) and converted to the molecular weight of standard polystyrene.

  The volume ratio of the first polymer segment to the second polymer segment (first polymer segment: second polymer segment) in the block copolymer is used to create a lamellar structure by self-assembly. It is preferably 3: 7 to 7: 3, and more preferably 4: 6 to 6: 4. When such a volume ratio is outside the above range, it tends to be difficult to form an uneven pattern due to the lamellar structure.

  Moreover, the block copolymer solution used for process (I) can be prepared by melt | dissolving the said block copolymer in a solvent. Examples of such a solvent include aliphatic hydrocarbons such as hexane, heptane, octane, decane, and cyclohexane; aromatic hydrocarbons such as benzene, toluene, xylene, and mesitylene; ethers such as diethyl ether, tetrahydrofuran, and dioxane. Ketones such as acetone, methyl ethyl ketone, isophorone and cyclohexanone; ether alcohols such as butoxyethyl ether, hexyloxyethyl alcohol, methoxy-2-propanol and benzyloxyethanol; ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triglyme, propylene glycol monomethyl Glycol ethers such as ether and propylene glycol monomethyl ether acetate; ethyl acetate, ethyl lactate, γ Esters such as butyrolactone; phenols such as phenol and chlorophenol; amides such as N, N-dimethylformamide, N, N-dimethylacetamide and N-methylpyrrolidone; chloroform, methylene chloride, tetrachloroethane, monochlorobenzene, di Halogen-based solvents such as chlorobenzene; hetero-containing compound such as carbon disulfide; and mixed solvents thereof. The content of the block copolymer in the block copolymer solution is preferably 0.1 to 15% by mass, and 0.3 to 5% by mass with respect to 100% by mass of the block copolymer solution. More preferably.

  In addition, the block copolymer solution may contain other homopolymer (a homopolymer other than the first homopolymer and the second homopolymer in the block copolymer contained in the solution: for example, block copolymer When the combination of the first homopolymer and the second homopolymer in the combination is a combination of polystyrene and polymethyl methacrylate, it may be a homopolymer of a type other than polystyrene and polymethyl methacrylate). It may further contain a surfactant, an ionic compound, an antifoaming agent, a leveling agent and the like.

When the block copolymer solution contains another homopolymer, the shape (for example, the depth of the unevenness) of the microphase separation structure formed by the block copolymer can be changed. For example, polyalkylene oxide can be used to deepen the depth of the unevenness formed by the microphase separation structure. As such polyalkylene oxide, polyethylene oxide and polypropylene oxide are more preferable, and polyethylene oxide is particularly preferable. Moreover, as such polyethylene oxide, the following formula:
_{HO- (CH 2 -CH 2 -O)} n-H
[Wherein, n represents an integer of 10 to 5000 (more preferably an integer of 50 to 1000, still more preferably an integer of 50 to 500). ]
The thing represented by these is preferable.

  If the value of n is less than the lower limit, the molecular weight is too low and is lost due to volatilization / evaporation, etc. by heat treatment at high temperature, and the effect of containing other homopolymers tends to be poor. When the upper limit is exceeded, the molecular weight is too high and the molecular mobility is low, so that the phase separation rate is slow and the microphase separation structure cannot be formed efficiently.

  Moreover, the number average molecular weight (Mn) of such other homopolymers is preferably 460 to 220,000, and more preferably 2200 to 46000. If the number average molecular weight is less than the lower limit, the molecular weight is too low and lost due to volatilization / evaporation, etc. by heat treatment at high temperature, and the effect of containing other homopolymer tends to be poor, When the upper limit is exceeded, the molecular weight is too high and the molecular mobility becomes low, so that the phase separation rate is slowed and the micro phase separation structure cannot be efficiently formed.

  The molecular weight distribution (Mw / Mn) of such another homopolymer is preferably 1.5 or less, and more preferably 1.0 to 1.3. If the molecular weight distribution exceeds the above upper limit, the uniformity of the microphase separation shape tends to be difficult to be maintained. In addition, such number average molecular weight (Mn) and weight average molecular weight (Mw) are values measured by gel permeation chromatography (GPC) and converted to the molecular weight of standard polystyrene.

  When such other homopolymer is used, the combination of the first homopolymer and the second homopolymer in the block copolymer is a combination of polystyrene and polymethyl methacrylate (polystyrene-polymethyl methacrylate). And the other homopolymer is preferably a polyalkylene oxide. In this way, by using a combination of a polystyrene-polymethylmethacrylate block copolymer and polyalkylene oxide, the vertical orientation can be further improved, and the depth of surface irregularities can be further increased. In addition, the heat treatment time during production can be shortened.

  When the other homopolymer is used in the block copolymer solution, the content thereof is preferably 100 parts by mass or less with respect to 100 parts by mass of the block copolymer, and 5 to 100 parts by mass. More preferably, it is part by mass. If the content of such other homopolymers is less than the lower limit, the effect obtained by incorporating other homopolymers tends to be poor.

  Moreover, when using the said surfactant, it is preferable that the content is 10 mass parts or less with respect to 100 mass parts of said block copolymers. Furthermore, when using the said ionic compound, it is preferable that the content is 10 mass parts or less with respect to 100 mass parts of said block copolymers.

  Further, when the other homopolymer is contained in the block copolymer solution, the total content of the block copolymer and the other homopolymer is 0.1% in the block copolymer solution. It is preferable that it is -15 mass%, and it is more preferable that it is 0.3-5 mass%. When the total content is less than the lower limit, it is not easy to uniformly apply the solution with a sufficient film thickness in order to obtain a required film thickness. When the upper limit is exceeded, the solution is uniformly dissolved in the solvent. Is relatively difficult to prepare.

  The substrate used in step (I) is not particularly limited. For example, polyimide, polyphenylene sulfide (PPS), polyphenylene oxide, polyether ketone, polyethylene naphthalate, polyethylene terephthalate, polyarylate, triacetyl cellulose, poly Resin substrates such as cycloolefin; glass, octadecyldimethylchlorosilane (ODS) -treated glass, octadecyltrichlorosilane (OTS) -treated glass, organosilicate-treated glass, silicon substrate, and other inorganic substrates; metal substrates such as aluminum, iron, and copper It is done. Moreover, such a base material may be subjected to a surface treatment such as an orientation treatment. In addition, by treating the substrate surface such as glass with ODS or organosilicate in this way, in the heating process described later, the microphase separation structure such as a lamellar structure, a cylinder structure, or a spherical structure is perpendicular to the surface. It becomes easy to arrange. This is because the domain of each block constituting the block copolymer is easily aligned in the vertical direction by reducing the difference in interfacial energy between the block copolymer component and the substrate surface.

  Furthermore, the method for applying the block copolymer solution on the substrate is not particularly limited, and for example, spin coating, spray coating, dip coating, dropping, gravure printing, screen printing, A relief printing method, a die coating method, a curtain coating method, and an ink jet method can be employed.

  Moreover, as thickness of the coating film of the said block copolymer formed on a base material, it is preferable that the thickness of the coating film after drying is 10-3000 nm, and it is more preferable that it is 50-500 nm.

<Process (II)>
Step (II) is a step of drying the coating film on the substrate. Although the drying process of such a coating film is not particularly limited, it may be performed in an air atmosphere. Moreover, as a drying temperature in such a process, what is necessary is just a temperature which can remove a solvent from the said coating film, Although it does not restrict | limit in particular, It is preferable that it is 30-200 degreeC, and is 40-100 degreeC. It is more preferable. In addition, by such drying, the said block copolymer may begin to form a micro phase separation structure, and an unevenness | corrugation may be formed in the surface of a coating film (thin film).

<Process (III)>
Step (III) is a step (first heating step) in which the coating film dried in step (II) is heated at a temperature equal to or higher than the glass transition temperature (Tg) of the block copolymer.

  In this way, by heating the coating film at a temperature equal to or higher than the glass transition temperature (Tg) of the block copolymer in the coating film, the self-organization of the block copolymer in the coating film proceeds, and the block The copolymer can be microphase-separated into portions of the first polymer segment and the second polymer segment, whereby a microphase-separated structure can be efficiently formed.

  In the first heating step (III), the heating temperature is set to a temperature equal to or higher than the glass transition temperature (Tg). When such a heating temperature is lower than the glass transition temperature (Tg) of the block copolymer, the molecular mobility of the polymer is low, the self-assembly of the block copolymer does not proceed sufficiently, and the microphase separation structure is sufficient. Or the heating time for sufficiently producing a microphase separation structure tends to be long. Further, the upper limit of the heating temperature is not particularly limited as long as it is a temperature at which the block copolymer is not thermally decomposed. A method for performing such a first heating step is not particularly limited, and for example, a method of appropriately using an oven or the like in an air atmosphere may be employed. Note that the heating and heating steps (steps (II) and (III)) may be performed continuously by gradually increasing the heating temperature. In addition, when drying temperature and a heating process are continuously implemented by gradually increasing the heating temperature in this way, the drying process (process (II)) is a process included in the heating process (process (III)).

<Process (IV)>
Step (IV) is a step (etching step) in which after the step (III) is applied, the second polymer (segment) is removed by etching the coating film to form an uneven structure on the substrate.

  In such an etching step (IV), since the molecular structures of the first polymer segment and the second polymer segment are different, the etching rates (ease of being etched) are different. One polymer segment constituting the block copolymer (the second polymer segment) can be selectively removed according to the type of homopolymer of the two polymer segments. This is a step of selectively removing the second polymer segment) by etching. By removing the second polymer segment from the coating film by such an etching process, a remarkable uneven structure derived from the microphase separation structure of the block copolymer (structure formed by the process (III)) is efficiently obtained. It can be formed in the film.

  Thus, as an etching process for selectively removing one polymer segment, for example, a reactive ion etching method, an ozone oxidation method, a hydrolysis method, a metal ion staining method, an ultraviolet etching method or the like is used. The law can be adopted as appropriate. Further, as the etching treatment, the covalent bond of the block copolymer is treated with at least one selected from the group consisting of an acid, a base and a reducing agent to cut the covalent bond, and then only one polymer segment A method of removing only one polymer segment while maintaining the microphase separation structure may be adopted by washing the coating film on which the microphase separation structure is formed with a solvent or the like that dissolves.

<Process (V)>
Step (V) is a step (second heating step) in which the concavo-convex structure formed in step (IV) is heated at a temperature equal to or higher than the glass transition temperature (Tg) of the first polymer (segment). Such a second heating step (v) is performed as a so-called annealing treatment, and the line connecting the lowermost part of the concave part and the apex of the convex part forming the concave-convex structure by such heating is smoother. As a result, the kurtosis of the concavo-convex shape becomes smaller.

  The heating temperature in the second heating step (V) is preferably not less than the glass transition temperature of the first polymer segment remaining after etching (above the glass transition temperature of the first homopolymer). More preferably, it is not lower than the glass transition temperature and not higher than the temperature (Tg + 70 ° C.) that is 70 ° C. higher than the glass transition temperature of the first homopolymer. If such a heating temperature is lower than the glass transition temperature of the first homopolymer, a desired concavo-convex structure cannot be obtained after the electroforming process described later, or a long time is required for heating to form the desired concavo-convex structure. It tends to cost. On the other hand, when the heating temperature exceeds the upper limit, the entire first polymer segment is melted or decomposed, and the uneven shape tends to be largely collapsed. As a method for actually carrying out such a second heating step, for example, similarly to the first heating step, for example, an atmosphere or the like may be appropriately used in an air atmosphere. Moreover, it is preferable that it is 10 minutes-100 hours as a heating time in such a 2nd heating process.

  Note that the concavo-convex structure after the etching step (IV) has a rough side surface of the groove defined by the concavo-convex structure, and concavo-convex (including overhang) occurs in a direction perpendicular to the thickness direction. It can have such a complicated cross-sectional structure. Such irregularities present on the side surfaces of the convex portions tend to be more likely to occur as the molecular weight of the block copolymer increases. On the other hand, the molecular weight of the block copolymer is deeply related to the microphase separation structure and thus the pitch of the diffraction grating obtained therefrom. Therefore, in order to more efficiently achieve a suitable pitch distribution of the first unevenness, even when a relatively high molecular weight block copolymer is used, such a desired pitch distribution can be obtained by electroforming. In order to obtain a concavo-convex structure having characteristics more reliably, it can be said that it is preferable to perform the second heating step as described above. In such second heating step (V), the first polymer segment constituting the side surface of the concavo-convex shape is annealed by heating the concavo-convex structure after performing the etching step (IV), and the first polymer segment It is possible to make the defined cross-sectional shape a relatively smooth inclined surface (make the line connecting the lowest part of the concave part and the apex of the convex part smoother), and upward from the base material The shape is a tapered mountain shape (referred to herein as a “mountain structure”). In this way, the unevenness on the side surface is annealed by heating, and the overhang portion becomes a smooth slope by heating. Therefore, in the unevenness of the mountain structure obtained in the second heating step (V), the first polymer segment is made of metal. After the layer is deposited, the metal layer can be more easily peeled off, and the uneven shape can be efficiently transferred to the metal layer.

  Here, when the side surface of the groove defined by the concavo-convex structure after the etching step (IV) is rough and concavo-convex (including overhang) occurs in the direction orthogonal to the thickness direction, A portion where the seed layer for electroforming does not adhere tends to occur, and it tends to be difficult to deposit the metal layer uniformly by electroforming. Therefore, when the layer of the first polymer segment having a rough concavo-convex structure is used as it is, the mechanical strength of the obtained mold is lowered, and defects such as mold deformation and pattern defects tend to occur. It is in. Also, in electroforming (electroplating), the plating thickness of each part differs depending on the shape of the object to be plated, and the plating metal is easily drawn to the convex part or protruding corner of the object, Since it is difficult to draw, a complicated uneven cross-sectional structure with a rough side surface tends to have difficulty in obtaining an electroformed film having a uniform film thickness. Furthermore, even if such a complicated cross-sectional structure can be transferred to a mold obtained by electroforming, if the mold is pressed against the diffraction grating forming material to transfer the uneven shape, the diffraction grating forming material is In some cases, the mold cannot be peeled off from the cured resin, or the weak part of the mold is broken, resulting in a pattern defect. In view of these points as well, it is preferable to perform the second heating step as described above from the viewpoint of more reliably obtaining an uneven structure having such characteristics as desired pitch distribution by electroforming.

Thus, the base material which has the unevenness | corrugation (irregularity of a mountain-shaped structure) obtained by giving a 2nd heating process (V) can be used suitably as a master for the transfer to the metal in a post process. Therefore, as the irregularities of the chevron structure, when the irregularity analysis image obtained by analyzing the irregularity shape using an atomic force microscope is subjected to two-dimensional fast Fourier transform processing to obtain a Fourier transform image, the Fourier transform The image shows a circular or annular pattern whose center is the origin where the absolute value of the wave number is 0 μm ⁻¹ , and the absolute value of the wave number is 10 μm ^−1. It is preferable to satisfy the conditions that it exists in a region within the following range, and that the standard deviation of the depth distribution of the unevenness is 15 to 50 nm. Moreover, as an average pitch of the unevenness | corrugation of such a mountain-shaped structure, it is preferable that it is the range of 10-700 nm, and it is more preferable that it is the range of 100-700 nm. If the average pitch of the irregularities is less than the lower limit, the pitch is too small with respect to the wavelength of visible light, so that the diffraction grating obtained using such a matrix tends not to generate the necessary visible light diffraction, When the upper limit is exceeded, the diffraction angle of the diffraction grating obtained using such a matrix becomes small, and the function as the diffraction grating tends to be insufficient. In addition, the average pitch of unevenness means the average value of the unevenness pitch when the unevenness pitch (interval between adjacent protrusions or adjacent recesses) on the surface of the unevenness of the mountain structure is measured. In addition, the average value of the pitch of the unevenness is obtained by analyzing the unevenness of the surface using a scanning probe microscope (for example, product name “E-sweep” manufactured by SII Nano Technology Co., Ltd.). Is measured, 100 or more intervals between adjacent adjacent convex portions or adjacent concave portions in the unevenness analysis image are measured, and a value calculated by calculating the average is adopted.

  Moreover, the average height of the unevenness formed on the substrate is preferably in the range of 20 to 200 nm, more preferably in the range of 30 to 100 nm, and still more preferably in the range of 40 to 80 nm. . If the average height of the irregularities is less than the lower limit, the height is insufficient with respect to the wavelength of visible light, so that diffraction tends to be insufficient. On the other hand, if the upper limit is exceeded, the obtained diffraction grating is used as an organic EL element. When used as an optical element on the light extraction opening side, the electric field distribution inside the EL layer becomes non-uniform and the element is easily destroyed due to heat generation due to the concentration of the electric field at a specific location, and the life is likely to be shortened. There is a tendency. In addition, the average height of unevenness | corrugation here means the average of the height of unevenness | corrugation in the case of measuring the height of unevenness | corrugation in the surface in which the uneven | corrugated shape was formed (distance of a recessed part and a convex direction of a depth direction). The value. In addition, the average value of the height of such irregularities is obtained by analyzing the irregularities on the surface using a scanning probe microscope (for example, product name “E-sweep” manufactured by SII Nano Technology Co., Ltd.). After measuring the image, 100 or more distances in the depth direction from the arbitrary concave and convex portions in the unevenness analysis image are measured, and a value calculated by calculating the average is adopted.

  Note that the unevenness characteristics (average height, average pitch, average value (m), etc.) of the base material having such unevenness (irregularities of the chevron structure) are the type of block copolymer, the heating temperature during the heat treatment, etc. It is possible to easily adjust to a desired characteristic by adjusting.

<Step (VI) to Step (VIII)>
Step (VI) is a step of forming a seed layer on the concavo-convex structure after the step (V) is applied, and step (VII) is a metal layer formed by electroforming (electroplating) on the seed layer. The step (VIII) is a step of peeling the base material having the concavo-convex structure from the metal layer and the seed layer. Each of these steps will be described below with reference to FIGS.

  FIG. 3 is a cross-sectional view schematically showing a transfer master 30 in which a layer 21 made of a first polymer segment having chevron-shaped irregularities is formed on a substrate 20, and FIG. FIG. 5 is a cross-sectional view schematically showing a state in which the seed layer 22 is formed on the irregularities on the surface of the layer 21 made of the first polymer segment in the master 30, and FIG. FIG. 6 is a cross-sectional view schematically showing a state in which the metal layer 23 and the seed layer 22 are peeled from the transfer master 30.

  In the step (VI), the seed layer 22 is formed on the concavo-convex structure of the base material (transfer master 30) having the concavo-convex structure obtained after the step (V) (see FIGS. 3 and 4). ).

  Such a seed layer 22 is a layer that becomes a conductive layer for a subsequent electroforming process. The method for forming the seed layer 22 is not particularly limited, and a so-called conductive layer can be formed on the concavo-convex layer 21 formed on the surface of the substrate 20 while maintaining the concavo-convex shape. Possible known methods can be used as appropriate, and for example, they can be formed by a method such as electroless plating, sputtering or vapor deposition.

  Further, the thickness of the seed layer 22 is such that the current density in the subsequent electroforming process can be made uniform and the thickness of the metal layer deposited by the subsequent electroforming process can be made constant. However, it is preferably 10 nm or more, and more preferably 100 nm or more, since higher effects can be obtained. The seed layer material is not particularly limited. For example, nickel, copper, gold, silver, platinum, titanium, cobalt, tin, zinc, chromium, gold-cobalt alloy, gold-nickel alloy, boron- Nickel alloy, solder, copper / nickel / chromium alloy, tin / nickel alloy, nickel / palladium alloy, nickel / cobalt / phosphorus alloy, or alloys thereof can be used.

  Thus, after forming the seed layer 22 on the surface (uneven surface) of the layer 21 composed of the first polymer segment of the transfer master 30, a metal layer is formed on the seed layer by electroforming (electroplating). (Step (VII): see FIG. 5).

  The thickness of the metal layer 23 is not particularly limited. For example, the thickness including the thickness of the seed layer 22 may be 10 to 3000 μm as a whole. As the material of the metal layer 23 deposited by electroforming, any of the above metal species that can be used as the seed layer 22 can be used. As a material for such a metal layer 23, nickel is preferable from the viewpoint of wear resistance and releasability of the mold to be obtained. In this case, it is preferable to use nickel for the seed layer 22.

Moreover, it does not restrict | limit especially as electrocasting conditions at the time of forming the metal layer 23, You may employ | adopt suitably the conditions employ | adopted in the well-known electroplating method. In addition, the current density at the time of such electroforming is, for example, 0.03 to 10 A / cm ² from the viewpoint of suppressing the bridge and forming a uniform metal layer and shortening the electroforming time. Good.

  In addition, since the metal layer 23 performs processing such as pressing, peeling, and washing with respect to the resin layer when using the mold including the metal layer 23 and the seed layer 22, it is appropriate from the viewpoint of ease of the processing. It preferably has hardness and thickness. From this point of view, the surface of the metal mold may be subjected to diamond-like carbon (DLC) treatment or Cr plating treatment for the purpose of improving the hardness of the metal layer 23 formed by electroforming, or The metal layer 23 may be further heat treated to increase its surface hardness.

  Thus, after forming the metal layer 23, as shown in FIG. 6, the metal part 31 composed of the metal layer 23 and the seed layer 22 is peeled from the base material (transfer master 30) having an uneven structure. (Step (VIII)).

  The metal part 31 composed of the seed layer 22 and the metal layer 23 thus obtained is peeled off from the base material having the concavo-convex structure, whereby a matrix (mold) for forming a diffraction grating can be obtained. That is, in this way, a master 31 (mold) 31 for forming a diffraction grating composed of the seed layer 22 and the metal layer 23 can be obtained.

  The method for peeling off such a diffraction grating forming matrix (mold) 31 is not particularly limited, and a known method can be used as appropriate, and a method of physically peeling off can be used. 1. Method of peeling mold (metal part) 31 by dissolving and removing the homopolymer and the remaining block copolymer using an organic solvent that dissolves them, for example, toluene, tetrahydrofuran (THF), chloroform, etc. May be used. In addition, the mold 31 obtained in this way is obtained by transferring (reversing) the unevenness characteristics of the transfer master 30.

  In addition, when the master 31 (mold) 31 for forming the diffraction grating is peeled from the master 30 for transfer (the substrate 10 on which the layer 21 having projections and depressions in the mountain structure is laminated), depending on the method of the peeling treatment, A part of the polymer such as the first polymer segment may remain attached to the surface of the mold. In such a case, it is preferable to remove the polymer adhered and remaining on the surface of the mold by washing. As such a cleaning method, wet cleaning or dry cleaning can be used. Examples of the wet cleaning method include a method of removing by washing with an organic solvent such as toluene and tetrahydrofuran, a surfactant, and an alkaline solution. Note that when an organic solvent is used, ultrasonic cleaning may be performed. Further, the polymer remaining after adhering to the mold surface may be removed by electrolytic cleaning. Examples of the dry cleaning method include a method of removing by ashing using ultraviolet rays or plasma. Further, the polymer remaining attached to the surface of the mold may be removed by washing using a combination of such wet washing and dry washing. Further, after such washing, rinsing with pure water or purified water may be performed, and ozone drying may be performed after drying. Further, the polymer remaining on the mold surface is removed by applying a resin film (for example, UV curable resin) to the mold and curing it, and then repeatedly removing and removing the cured film. May be.

In the above, the method for manufacturing a matrix (mold) for forming a diffraction grating including steps (I) to (VIII) has been described. The method is not particularly limited, and a known method can be appropriately used. For example, the block co-polymer obtained by carrying out steps (I) to (IV) (preferably also carrying out step (V)). The resin layer having a concavo-convex structure derived from the combined microphase separation structure may be used as a mold as it is, or the steps (I) to (IV) are carried out (preferably the step (V) is also carried out). Using the resin layer having a concavo-convex structure derived from the microphase separation structure of the block copolymer obtained above, a transfer material (material other than the seed layer and the metal layer described above) is formed on the surface of the concavo-convex structure of the resin layer. ) Is attached and cured, then removed Further, an uneven transfer member having unevenness formed on the surface may be obtained, and this may be used as a mother mold (mold) for forming a diffraction grating. Further, the steps (I) to (VIII) are performed. A diffraction grating may be formed using the obtained mold, and the obtained diffraction grating may be used as a new mold (mold) for forming a diffraction grating. Such a transfer material is not particularly limited. For example, silicone polymer (silicone rubber), urethane rubber, norbornene resin, polycarbonate, polyethylene terephthalate, polystyrene, polymethyl methacrylate, acrylic resin, liquid crystal polymer, epoxy resin, etc. The resin composition may be used. Further, the method for attaching such a transfer material is not particularly limited, and for example, vacuum deposition method; spin coating method, spray coating method, dip coating method, dropping method, gravure printing method, screen printing method, letterpress printing Various coating methods such as a method, a die coating method, a curtain coating method, an ink jet method, and a sputtering method can be employed. The conditions for curing the transfer material vary depending on the type of transfer material to be used. For example, the curing temperature is in the range of room temperature to 250 ° C., and the curing time is in the range of 0.5 minutes to 3 hours. Is preferred. It is also possible by a method of curing by irradiation of energy rays such as ultraviolet rays or electron beams, in that case, it is preferable dose is in the range of ^{20mJ / cm 2 ~10J / cm 2} . In addition, a final mold (matrix) may be manufactured by repeating the process of using the transfer material and repeating the inversion and transfer of the unevenness. By repeating the inversion and transfer of irregularities using such a transfer material, irregularities (including overhangs) are generated on the side surfaces of the irregularities before the inversion and transfer of the irregularities (master's irregular structure). Even in such a case, it is possible to make the cross-sectional shape smooth for each process (to make the line connecting the bottom of the concave portion and the top of the convex portion smoother). Become. Therefore, by repeating reversal and transfer of the unevenness using such a transfer material, unevenness (including overhangs) is formed on the side surface of the protrusion of the uneven structure (master uneven structure) before reversing and transferring the unevenness. Even when such a phenomenon occurs, the shape of the unevenness can be set to a desired shape (for example, the above-described mountain shape).

  In addition, as another method for manufacturing such a diffractive grating-forming matrix (mold) with irregularities formed, for example, from a polymer whose volume is changed by heat under a temperature condition of 70 ° C. or higher. Forming a vapor deposition film on the surface of the polymer film, and then cooling the polymer film and the vapor deposition film to form irregularities due to wrinkles on the surface of the vapor deposition film; and After the mold material is attached and cured, a method including the step (ii) of obtaining the matrix by removing the cured matrix material from the deposited film may be used. Hereinafter, the process (i) and the process (ii) will be described separately.

<Process (i)>
In the step (i), after forming a vapor deposition film on the surface of a polymer film made of a polymer whose volume is changed by heat under a temperature condition of 70 ° C. or higher, the polymer film and the vapor deposition film are cooled, thereby This is a step of forming irregularities by wrinkles on the surface of the deposited film. In such a process, first, a polymer film made of a polymer whose volume is changed by heat is prepared on a polymer film forming substrate. As such a polymer whose volume is changed by heat, a polymer whose volume is changed by heating or cooling (for example, a coefficient of thermal expansion of 50 ppm / K or more) can be appropriately used. From the viewpoint that the difference between the thermal expansion coefficient of the deposited film and the thermal expansion coefficient of the deposited film is large and has high flexibility, and it is easy to form irregularities due to wrinkles on the surface of the deposited film, a silicone-based polymer is more preferable and contains polydimethylsiloxane. Particularly preferred is a silicone polymer. In addition, the method for forming such a polymer film is not particularly limited. For example, a spin coating method, a dip coating method, a dropping method, a gravure printing method, a screen printing method, a relief printing method, a die coating method, and a curtain coating method. In addition, a method of applying the polymer on the substrate by employing an inkjet method, a spray coating method, a sputtering method, a vacuum deposition method, or the like can be employed.

  The polymer film-forming substrate is not particularly limited, and a known substrate (such as a glass substrate) that can be used for forming a polymer film can be appropriately used. In addition, the thickness of the polymer film thus formed is preferably in the range of 10 to 5000 μm, and more preferably in the range of 10 to 2000 μm. Such a polymer film may be used as it is laminated on the substrate, or may be used after being detached from the substrate.

  In step (i), after preparing the polymer film, a vapor deposition film is formed on the surface of the polymer film under a temperature condition of 70 ° C. or higher. The temperature at which the deposited film is formed needs to be 70 ° C. or higher, and more preferably 90 ° C. or higher. If the said temperature is less than 70 degreeC, the unevenness | corrugation by wrinkles cannot fully be formed in the surface of a vapor deposition film. As a method for forming the vapor deposition film, a known method such as a vapor deposition method or a sputtering method can be appropriately employed. Among these methods, it is preferable to employ a vapor deposition method from the viewpoint of maintaining the shape of the unevenness formed on the surface of the polymer film. The material of the deposited film is not particularly limited, and examples thereof include metals such as aluminum, gold, silver, platinum, and nickel, and metal oxides such as aluminum oxide.

  Furthermore, in the step (i), after forming the vapor deposition film on the surface of the polymer film as described above, the polymer film and the vapor deposition film are cooled to form irregularities due to wrinkles on the surface of the vapor deposition film. As described above, when the deposited film is cooled after being formed on the polymer film, the volume of the polymer film and the deposited film changes, but the thermal expansion coefficient of the material forming the polymer film and the thermal expansion of the material forming the deposited film are different. Since there is a difference between the coefficients, the rate of change in volume of each layer is different, and irregularities (so-called buckling pattern or so-called Turing pattern) due to wrinkles are formed on the surface of the deposited film. Further, the temperature of the polymer film and the deposited film after cooling is preferably 40 ° C. or lower. When the temperature of the polymer film and the deposited film after cooling exceeds the upper limit, it tends to be difficult to form irregularities due to wrinkles on the surface of the deposited film. Furthermore, it is preferable that the cooling rate when cooling the polymer film and the deposited film is in the range of 1 to 80 ° C./min. When the temperature lowering rate is less than the lower limit, the unevenness tends to be relaxed, and when it exceeds the upper limit, scratches such as cracks tend to occur on the surface of the polymer film or the deposited film.

<Process (ii)>
Step (ii) is a step of obtaining a matrix for forming a diffraction grating by attaching a matrix material on the deposited film and curing it, and then removing the cured matrix material from the deposited film. In such a process, first, a matrix material is attached on the surface of the deposited film (a surface having an uneven shape).

  Such a matrix material is not particularly limited as long as the obtained matrix can maintain strength and hardness for use as an uneven mold, and is not particularly limited, for example, nickel, silicon , Silicon carbide, tantalum, glassy carbon, quartz, silica and other inorganic materials; silicone polymer (silicone rubber), urethane rubber, norbornene resin, polycarbonate, polyethylene terephthalate, polystyrene, polymethyl methacrylate, acrylic, liquid crystal polymer, etc. Things. Among these matrix materials, silicone polymers, nickel, silicon, silicon carbide, tantalum, glassy carbon, quartz, and silica are more preferable, and silicone polymers are preferable from the viewpoints of moldability, followability of fine shapes, and mold release. Even more preferred is a silicone polymer containing polydimethylsiloxane.

  In addition, the method for adhering the matrix material onto the surface on which the uneven shape of the vapor deposition film is formed is not particularly limited. For example, electroplating; vacuum vapor deposition method; spin coating method, spray coating method, Various coating methods such as a dip coating method, a dropping method, a gravure printing method, a screen printing method, a relief printing method, a die coating method, a curtain coating method, an ink jet method, and a sputtering method can be employed.

In step (ii), the matrix material is adhered on the surface of the deposited film as described above, and then the matrix material is cured. The conditions for curing the matrix material are different depending on the type of the matrix material to be used, and cannot be generally stated.For example, when a resin material is used, depending on the type of the material, The curing temperature is preferably in the range of room temperature to 250 ° C., and the curing time is preferably in the range of 0.5 minutes to 3 hours. Further, depending on the type of the matrix material, a method of curing the matrix material by irradiating energy rays such as ultraviolet rays and electron beams may be employed. In that case, the irradiation amount is 20 mJ / cm. A range of ^{2 to} 10 J / cm ² is preferable.

  In step (ii), after the matrix material is cured on the surface of the vapor deposition film as described above, a layer obtained by curing the matrix material is removed from the vapor deposition film, thereby forming a diffraction grating. Get a matrix for Thus, it does not specifically limit as a method of removing a matrix from a vapor deposition film, A well-known method is employable suitably.

  Further, when a matrix is manufactured using a polymer whose volume is changed by heat as a matrix material, the process (i) and the process (ii) may be repeated using the matrix as a polymer film. By repeatedly carrying out the steps (i) and (ii) in this way, the wrinkles formed on the surface of the mother die can be deepened, and the average height of the irregularities formed on the surface of the mother die The thickness can be increased.

  In addition, after the resin (the material used for the matrix material) was applied and cured on the surface of the matrix obtained by performing the steps (i) and (ii) in this manner, it was removed. In addition to applying a resin to the surface of the obtained mother mold, a concavo-convex film of a cured resin obtained by pressing the mother mold against a resin coating and curing the resin may be used. It may be a mother mold. In this way, a resin film with the irregularities reversed can also be used as a matrix.

  Further, the final mother die is manufactured by repeating the inversion and transfer of the unevenness through one or more intermediate mother dies from the mother dies obtained by performing the steps (i) and (ii). May be. As such an intermediate matrix, an appropriately inverted or transferred structure can be used. In addition, when the mother mold is manufactured by repeating the inversion and transfer of the irregularities in this way, when transferring the irregular structure of the mother mold, a non-flexible substrate (for example, a glass substrate) that is difficult to peel off the resin film or the like. In order to facilitate the transfer of the concavo-convex structure even when using), it is also possible to temporarily transfer it to a flexible material (for example, plastic film or silicone rubber). It tends to be easy to match (match even-odd). Further, a polymer film obtained by applying a polymer whose volume is changed by heat to these intermediate master molds and curing is used as a master mold, and the process (i) and the process (ii) are repeated. Also good. In addition, when the intermediate matrix is made of a UV curable resin, after the intermediate matrix is obtained by irradiating with ultraviolet light at the time of production, post-cure may be performed by irradiating the ultraviolet light again. Good. In this way, by carrying out post-cure by irradiating UV light to the mother mold made of UV curable resin again, the degree of cross-linking of the mother mold tends to improve, and mechanical strength and chemical resistance tend to improve. .

  In addition, the mother mold (including an intermediate mother mold) obtained by performing the steps (i) and (ii) is plated using a known method to convert the mother mold into metal gold It may be typed. By plating in this way to form a metal mold, there is a tendency to obtain a matrix that has excellent mechanical strength and can be used repeatedly. By using the matrix thus plated as a mold such as nanoimprint, it is possible to mass-produce a resin substrate having a predetermined concavo-convex pattern by repeatedly transferring it to a cured resin substrate. Examples of materials that can be used for such plating include nickel, copper, iron, nickel cobalt alloy, nickel iron alloy, and the like. In addition, it is preferable that the thickness of such a plating layer is 50 micrometers-1 mm from viewpoints, such as mechanical strength and time required for metal mold | die preparation. In addition, what is obtained by heating the mother die thus obtained under a temperature condition of about 80 to 200 ° C. under atmospheric pressure for about 1 to 48 hours may be used as a mother die used for manufacturing a diffraction grating.

  As the concave / convex shape of the diffraction grating forming master (mold) finally obtained by appropriately using the above method for manufacturing a diffraction grating forming master (mold), the first concave and convex portions described above are used. It is preferable to have similar characteristics. Such uneven shape can be easily adjusted by appropriately changing the type of polymer to be used, the heating conditions in the heating step, or repeating the transfer step.

  Next, the process of manufacturing a diffraction grating using the obtained master (mold) 31 for forming a diffraction grating will be described. That is, a material (diffraction grating forming material) for forming the diffraction grating (uneven layer) 11 is applied on the transparent support substrate, the matrix 31 is pressed while the matrix 31 is pressed, and the matrix is cured. A process of laminating the diffraction grating 11 with the irregularities formed on the transparent support substrate by removing 31 (process for manufacturing the diffraction grating) will be described.

  7 to 9 are schematic views for explaining a preferred embodiment of a method for manufacturing a diffraction grating. FIG. 7 is a cross-sectional view schematically showing a state in which the diffraction grating forming material 11 ′ is applied on the transparent support substrate 10, and FIG. 8 is a diagram in which the diffraction grating forming material is cured while pressing the matrix 31. FIG. 9 is a cross-sectional view schematically showing a state in which the mother die 31 is removed and irregularities are formed on the surface of the diffraction grating 11.

  In the process of manufacturing such a diffraction grating 11, first, a diffraction grating forming material 11 ′ is applied on the transparent support substrate 10 (see FIG. 7). Thereafter, the diffraction grating forming material is cured while pressing a diffraction grating forming mother mold (mold) 31 against the film of the diffraction grating forming material 11 ′ (see FIG. 8).

  Such a transparent support substrate 10 is the same as the transparent support substrate 10 described above. Further, as such a diffraction grating forming material 11 ′, the same materials (resin materials and transparent inorganic layer forming materials) described as materials for forming the above-mentioned diffraction grating 11 (uneven layer) are used. be able to.

  In the case where a transparent inorganic layer forming material is used as such a diffraction grating forming material 11 ′ (when the concavo-convex layer is an inorganic layer), in order to more efficiently form the concavo-convex layer to which the pattern is transferred by the sol-gel method, It is preferable to use a sol solution containing a metal material. Although it does not restrict | limit especially as a sol solution containing such a metal material, For example, when making an uneven | corrugated layer into an inorganic layer which consists of silica, the sol solution containing a silica precursor (metal alkoxide) is mentioned. It is done. Examples of such silica precursors include tetramethoxysilane (TMOS), tetraethoxysilane (TEOS), tetra-i-propoxysilane, tetra-n-propoxysilane, tetra-i-butoxysilane, and tetra-n-. Tetraalkoxide monomers such as butoxysilane, tetra-sec-butoxysilane, tetra-t-butoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, isopropyltrimethoxysilane, phenyltrimethoxysilane, methyltrimethoxysilane Ethoxysilane, ethyltriethoxysilane, propyltriethoxysilane, isopropyltriethoxysilane, phenyltriethoxysilane, methyltripropoxysilane, ethyltripropoxysilane, propyltripro Trialkoxide monomers such as xysilane, isopropyl tripropoxy silane, phenyl tripropoxy silane, methyl triisopropoxy silane, ethyl triisopropoxy silane, propyl triisopropoxy silane, isopropyl triisopropoxy silane, phenyl triisopropoxy silane, and these monomers And a metal alkoxide such as a composite material in which a functional group or a polymer is introduced into a part of the material. The sol solution may be a sol solution capable of forming an inorganic layer by a sol-gel method, and the type of metal material is not particularly limited, and besides metal alkoxide, metal acetylacetonate, metal carboxylate , Oxychlorides, chlorides, and mixtures thereof. Further, the metal species in such a metal material is not particularly limited, and any metal species other than silicon (Si) can be used to form an inorganic layer by a sol-gel method. For example, Ti, Sn, Al, Zn, Zr, In, or the like may be used as appropriate. Further, as the metal material, one kind may be used alone, or two or more kinds may be used in combination as a mixture. Moreover, as such a sol solution, what mixed suitably the precursor of the inorganic layer (The layer which consists of the said metal single-piece | unit or the said metal oxide) can also be used. Moreover, when using the mixture of TEOS and MTES for a sol solution, those compounding ratios in particular are not restrict | limited, It is good also as 1: 1.

  Furthermore, as a solvent of such a sol solution, for example, alcohols such as methanol, ethanol, isopropyl alcohol (IPA), butanol, aliphatic hydrocarbons such as hexane, heptane, octane, decane, cyclohexane, benzene, toluene, Aromatic hydrocarbons such as xylene and mesitylene, ethers such as diethyl ether, tetrahydrofuran and dioxane, ketones such as acetone, methyl ethyl ketone, isophorone and cyclohexanone, butoxyethyl ether, hexyloxyethyl alcohol, methoxy-2-propanol and benzyl Ether alcohols such as oxyethanol, glycols such as ethylene glycol and propylene glycol, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether Glycol ethers such as propylene glycol monomethyl ether acetate, esters such as ethyl acetate, ethyl lactate and γ-butyrolactone, phenols such as phenol and chlorophenol, N, N-dimethylformamide, N, N-dimethylacetamide, Examples thereof include amides such as N-methylpyrrolidone, halogen-based solvents such as chloroform, methylene chloride, tetrachloroethane, monochlorobenzene and dichlorobenzene, hetero-containing compounds such as carbon disulfide, water, and mixed solvents thereof. In particular, ethanol and isopropyl alcohol are preferable, and those in which water is mixed are also preferable.

  Examples of additives that can be added to the sol solution include polyethylene glycol, polyethylene oxide, hydroxypropyl cellulose, polyvinyl alcohol for viscosity adjustment, and alkanols such as triethanolamine, which is a solution stabilizer. Examples include β-diketones such as amine and acetylacetone, β-ketoesters, formamide, dimethylformamide, and dioxane.

  Further, the coating thickness of the diffraction grating forming material is preferably in the range where the thickness of the diffraction grating 11 is 0.01 to 500 μm. When the coating thickness of the diffraction grating forming material is less than the lower limit, the height of the unevenness formed on the surface of the uneven layer tends to be insufficient. On the other hand, when the upper limit is exceeded, the material generated when the uneven layer is cured. As a result, the influence of the volume change becomes large, and the uneven shape tends not to be formed well.

  Examples of the method for applying the diffraction grating forming material 11 ′ (including the sol solution) on the transparent support substrate 10 include spin coating, spray coating, dip coating, dropping, gravure printing, Various coating methods such as a screen printing method, a relief printing method, a die coating method, a curtain coating method, an ink jet method, and a sputtering method can be employed.

Furthermore, in the case where the diffraction grating forming material 11 ′ is a resin material, the condition for curing the diffraction grating forming material varies depending on the type of the resin material used. For example, the curing temperature is in the range of room temperature to 250 ° C. The curing time is preferably in the range of 0.5 minutes to 3 hours. In addition, when the diffraction grating forming material is a material that is cured by irradiating energy rays such as ultraviolet rays or electron beams, a method of irradiating energy rays may be employed. it is preferably in the range of ^{20mJ / cm 2 ~5J / cm 2} .

  Further, when the diffraction grating forming material is cured using the sol solution (when an inorganic layer is formed), it can be used in a so-called sol-gel method depending on the metal species and the type of metal material to be used. The hardened layer (inorganic layer) may be formed from the sol solution by appropriately adopting known conditions. For example, when forming an inorganic layer (concave / convex layer) made of silica using a sol solution containing a silica precursor, the inorganic layer is formed by synthesizing amorphous silica by hydrolysis and polycondensation reactions. Can be formed. Such hydrolysis and polycondensation reaction is not particularly limited as long as it is a condition capable of synthesizing amorphous silica, but an acid such as hydrochloric acid or ammonia is used to adjust the pH of the sol solution. It is preferable to add an alkali such as, and more preferably, the pH is 4 or less or 10 or more. In order to perform the hydrolysis, water may be added separately. In addition, in order to perform hydrolysis in this way, when adding water separately, it is preferable that the addition amount of the water shall be 1.5 times or more by molar ratio with respect to metal alkoxide seed | species. When a transparent inorganic layer forming material is used as the diffraction grating forming material 11 ′ (when the uneven layer is an inorganic layer), the diffraction grating forming matrix 31 is pressed against the coating film of the sol solution. In addition, it is preferable to use a heated pressing roll. In this way, by pressing the mold while heating the coating film, the mold can be cured while being pressed, and the uneven layer tends to be formed more efficiently. In addition, after the transparent inorganic layer forming material is cured to form an inorganic layer in this way, it is further heated at a temperature of 200 to 1200 ° C. for 5 minutes to 6 hours from the viewpoint of increasing mechanical strength. It is preferable to do.

  In the case where the diffraction grating 11 is formed of a transparent inorganic layer forming material, the heat resistance of the diffraction grating 11 tends to be improved as compared with the case where a resin material is used. Therefore, when the diffraction grating 11 is formed of a transparent inorganic layer forming material, a low-resistance transparent electrode (for example, ITO) can be efficiently formed by so-called heat sputtering, and an organic EL element with higher power efficiency can be obtained. In addition, even when the organic EL element is used under high temperature conditions, deterioration due to high temperature can be more sufficiently suppressed without causing the diffraction grating 11 to be discolored. Further, when the diffraction grating 11 is formed of a transparent inorganic layer forming material, it is possible to perform brush cleaning on the concavo-convex pattern surface of the diffraction grating 11 before elementization. When the transparent inorganic layer forming material is used as a material for forming the uneven layer, the mechanical strength of the surface of the uneven layer is higher than when using a resin material, so brush cleaning Since it is possible to sufficiently suppress the generation of scratches on the surface of the layer by the process (because basically no scratches are generated), the surface of the concavo-convex layer can be efficiently cleaned, and foreign matters on the surface can be more efficiently removed. Therefore, the occurrence of defects due to foreign matters on the surface can be sufficiently suppressed (the rate of occurrence of defects can be reduced). Furthermore, when the diffraction grating 11 is formed of a transparent inorganic layer forming material, it is possible to form a layer that is more excellent in chemical resistance than in the case of using a resin material, and the layer has a higher level of alkali resistance. It can also be improved. Therefore, various cleaning solvents can be used in the surface cleaning process. That is, it is possible to appropriately use an alkali or various organic solvents without selecting a cleaning liquid in the cleaning step before device fabrication. In addition, as described above, when the diffraction grating 11 is formed of a transparent inorganic layer forming material, a layer superior in chemical resistance can be formed compared to the case of using a resin material. There is a tendency that damage caused by the resist and the developer can be further reduced. In addition, when the diffraction grating 11 is formed of a transparent inorganic layer forming material, the UV resistance of the diffraction grating 11 can be made higher than that when a resin material is used. Therefore, when the diffraction grating 11 is formed of a transparent inorganic layer forming material, it is possible to efficiently clean and remove organic contaminants by UV ozone cleaning, and to reduce the defect rate derived from organic contaminants. In addition, it is possible to sufficiently suppress deterioration due to sunlight even when used outdoors, and to have a higher level of weather resistance.

  In such a manufacturing process of the diffraction grating, the mother die 31 is then removed from the cured diffraction grating 11 (see FIG. 9). As described above, the method for removing the matrix 31 from the cured diffraction grating 11 is not particularly limited, and a known method can be appropriately employed. In this way, the diffraction grating 11 having irregularities formed on the transparent support substrate 10 can be laminated.

  In order to improve the releasability from the diffraction grating forming material when such a process is carried out and the concavo-convex structure is transferred to the diffraction grating forming material using the mother mold (mold 31), A mold release process may be performed on the mold 31 in advance. As such a mold release treatment, a prescription for lowering the surface energy is generally used, and there is no particular limitation. However, a release agent such as a fluorine-based material or a silicone resin (for example, a product name manufactured by Daikin Chemicals Sales Co., Ltd.) Examples thereof include a method of coating “HD-2101TH”) on the uneven surface of the mold 31, a treatment with a fluorine-based silane coupling agent, and a method of forming a diamond-like carbon film on the surface.

  Thus, the transparent support base material 10 including the diffraction grating 11 having a desired pattern can be obtained. The transparent support base material 10 including the diffraction grating 11 thus obtained is used for forming the diffraction grating. The process of manufacturing the diffraction grating 11 may be performed again by using it as a mother mold. That is, an inverted pattern replica may be manufactured using the transparent support substrate 10 including the diffraction grating 11 as a matrix, and in this case, the replica may be used as the diffraction grating 11. Further, such reversal and transfer processes may be repeated. For example, the above-described transfer process may be repeated again with a replica of a reversal pattern as a matrix to form a child replica. As described above, the inversion and transfer of the unevenness may be repeated to finally form the diffraction grating 11 having the first unevenness. When replicas are sequentially replicated in this way, a film may be laminated on the surface of the concavo-convex layer used as a matrix by a vapor phase method such as vapor deposition or sputtering. By laminating films in this way, when performing transfer or the like by applying a resin to the surface, adhesion with the resin (for example, UV curable resin) can be reduced, and the matrix is peeled off. It becomes easy. Examples of such a deposited film include metals such as aluminum, gold, silver, platinum, and nickel, and metal oxides such as aluminum oxide. The thickness of such a film is preferably 5 to 500 nm. If the thickness is less than the lower limit, it is difficult to obtain a uniform film, and the effect of sufficiently reducing the adhesiveness is reduced. If the thickness exceeds the upper limit, the shape of the matrix tends to be distorted. When the concave / convex layer of the replica is made of a UV curable resin, post-cure may be appropriately performed by irradiating ultraviolet light again after the resin is cured.

(Organic EL element formation process)
Next, the organic EL element forming process will be described. In the organic EL element forming step, the transparent electrode 12, the organic layer 13 and the metal electrode 14 are formed on the surface of the diffraction grating 11 on the surface of the diffraction grating 11 obtained by the diffraction grating forming step. In this process, the organic EL elements are obtained by laminating each of the organic EL elements so as to maintain the shape.

  Thus, as a method for laminating the transparent electrode 12 on the diffraction grating so that the shape of the first unevenness is maintained, for example, using the transparent electrode material as described above, A method of laminating the transparent electrode 12 by a known method such as a vapor deposition method or a sputtering method can be suitably employed. In this way, by adopting a known method such as a vapor deposition method or a sputtering method, and laminating the transparent electrode while appropriately changing the conditions using the transparent electrode material as described above, The transparent electrode 12 having a sufficiently maintained shape can be formed. That is, since the material of the transparent electrode 12 is made of a metal or a metal oxide, the above-mentioned conditions can be changed by appropriately changing the deposition conditions and sputtering conditions while employing a known method such as a deposition method and a sputtering method. Can be easily formed with irregularities having a standard deviation (σ) in the range, standard deviation rate, and irregularities derived from the characteristics of the first irregularities (for example, kurtosis, average height, average pitch, inequality ( Regarding the condition of 1), the first unevenness satisfying the above condition can be easily formed. In addition, as a method of laminating the transparent electrode 12, it is possible to more efficiently form the irregularities having the standard deviation (σ) and the standard deviation rate in the above-described range. It is preferable to adopt.

  In addition, as a method of laminating such an organic layer 13 so that the shape of the first unevenness formed on the surface of the diffraction grating 11 is maintained, for example, each layer of the organic layer as described above is used. A method of sequentially laminating each layer of the organic layer 13 on the transparent electrode 12 by a known method such as a vapor deposition method or a sputtering method can be suitably employed by sequentially using the constituent materials. Further, among these methods, the shape of the first unevenness formed on the surface of the diffraction grating 11 can be more sufficiently maintained, and the standard deviation (σ) and the change of the standard deviation in the above-described range can be maintained. In addition to being able to more efficiently form the fourth to sixth irregularities having a ratio, the characteristics of the irregularities derived from the characteristics of the first irregularities (for example, regarding the conditions of kurtosis, average height, average pitch, inequality (1)) It is more preferable to employ the vacuum deposition method because the fourth to sixth irregularities having the same condition as the first irregularities can be more reliably formed. When the material other than the dopant material (however, the dopant material (phosphorescent material, etc.) constituting each of the hole transport layer, the light emitting layer, and the electron transport layer used in the above is capable of measuring the glass transition temperature. The Panto material including.) Both are, more preferably has a glass transition temperature of organic material 70 ° C. to 300 ° C.. By using an organic material having such a glass transition temperature, the material can be easily fixed at and near the site where the material arrives at the time of deposition (the site on the object to be coated). Each layer of the organic layer having a concavo-convex shape that sufficiently maintains the shape of the above can be more reliably formed, and thereby the concavo-convex having a standard deviation (σ) in the above range and a change rate of the standard deviation can be further improved. It can be formed efficiently. In addition, as a method of obtaining the light emitting layer in which the dopant material is dispersed, a known method can be appropriately employed. For example, a co-evaporation method using a host material and a dopant material may be employed.

  In addition, as a method of laminating the metal electrode 14 so that the shape of the first unevenness formed on the surface of the diffraction grating 11 is maintained, the organic layer is formed using the material of the metal electrode 14 described above. A method of laminating the metal electrode 14 on the substrate 13 by a known method such as vapor deposition or sputtering can be suitably employed. Among these methods, the shape of the first unevenness formed on the surface of the diffraction grating 11 can be more sufficiently maintained, and the standard deviation (σ) and the rate of change of the standard deviation in the above range can be set. The second unevenness can be more efficiently formed, and the unevenness derived from the characteristics of the first unevenness (for example, the first unevenness with respect to the conditions of kurtosis, average height, average pitch, inequality (1) Since it is also possible to form the second unevenness having the above-mentioned conditions that satisfy the above-mentioned conditions, it is preferable to employ a vacuum deposition method.

(Optical member placement process)
Next, the optical member arranging step will be described. Such an optical member disposing step is a step of disposing the optical member on the surface opposite to the surface on which the diffraction grating of the transparent support substrate is disposed (the surface that becomes the light extraction surface after the element is formed). In such a process, the optical member 15 may be laminated on the transparent support substrate 10 via an adhesive layer and / or an adhesive layer. Thus, when the optical member 15 is laminated and disposed via the pressure-sensitive adhesive layer and / or the adhesive layer, for example, an adhesive is used on the surface of the transparent support substrate 10 opposite to the surface on which the diffraction grating is disposed. The transparent resin substrate 10 using a method of laminating the optical member 15 and a method of laminating the optical member 15 using an adhesive on the surface opposite to the surface on which the diffraction grating is disposed on the transparent support substrate 10. The optical member 15 may be laminated and arranged on the substrate.

  Moreover, as a material for the pressure-sensitive adhesive layer and / or the adhesive layer, a known material (pressure-sensitive adhesive and adhesive) capable of bonding the optical member 15 onto the transparent support substrate 10 can be appropriately used. Synthetic rubber systems such as acrylic adhesives, ethylene-vinyl acetate copolymers, natural rubber adhesives, polyisobutylene, butyl rubber, styrene-butylene-styrene copolymers, styrene-imprene-styrene block copolymers, etc. A pressure-sensitive adhesive, polyurethane-based pressure-sensitive adhesive, or polyester-based pressure-sensitive adhesive may be used as appropriate. May be used. The method for applying such a pressure-sensitive adhesive and adhesive is not particularly limited, and a known method can be appropriately employed. Such a pressure-sensitive adhesive and adhesive may be applied to either the transparent support substrate 10 or the optical member 15. Moreover, such an optical member arrangement | positioning process may be implemented before formation of the diffraction grating 11, or may be implemented after formation of the diffraction grating 11, and the order which implements these processes is restrict | limited especially. It is not a thing.

  In addition, when using the microlens which consists of an uneven | corrugated layer as the optical member 15, as a method for manufacturing the microlens which consists of an uneven | corrugated layer, it is the same material as a diffraction grating formation material on one surface of a planar support material. And a method including a step of removing the mother die after curing the material while pressing the mother die (a method basically similar to the diffraction grating forming step described above: a microlens having a desired shape) In order to obtain the above, it is possible to appropriately change the above-described diffraction grating forming process and manufacturing conditions. For example, a mother for a microlens having desired characteristics can be obtained by repeatedly transferring and inverting the master mold while appropriately changing the material. A method of manufacturing a mold and using this to manufacture a microlens having a desired shape may be used. When such a method is employed, a transparent support substrate 10 can be suitably used as the support material. As described above, when the transparent support substrate 10 is used as the support material, the microlens can be used as it is without peeling off the support material, and an adhesive layer and / or an adhesive layer or the like can be used. Therefore, it is not necessary to perform a step of laminating and arranging microlenses (optical member 15) made of a concavo-convex layer, so that the manufacturing process of the organic EL element can be simplified. In the case where a material other than the transparent support substrate 10 is used as the support material, a resin film (a film of TAC, PET, COP, PC, etc.) can be used as the support material. When a laminated body of microlenses in a state of being laminated on such a resin film is obtained, the laminated body of microlenses may be laminated on the transparent support substrate 10 as it is. The microlens may be peeled from the material and only the microlens may be laminated on the transparent support substrate 10. Thus, when manufacturing a microlens (unevenness | corrugation layer) with a film form separately, it is possible to bond on the surface of the transparent resin substrate 10 with the form, and the micro which consists of the formed unevenness | corrugation layer. When scratches or defects are found in the lens, the portion can be removed, and when a defect is found on the element side, the defective product can be removed, so that the yield can be improved. The thickness of the support material is not particularly limited, but is preferably in the range of 1 to 500 μm.

  As mentioned above, although preferred embodiment of the organic EL element of this invention was described based on the organic EL element of embodiment shown in FIG. 1, the organic EL element of this invention is not limited to the said embodiment. For example, in the organic EL element of the embodiment shown in FIG. 1, the organic layer has a structure in which the hole transport layer / the light emitting layer / the electron transport layer are stacked in this order. As long as it includes a transparent support substrate, a diffraction grating, a transparent electrode, an organic layer including at least a light emitting layer, a metal electrode, and an optical member, the configuration of the organic layer is not particularly limited.

  That is, in the present invention, the organic layer laminated on the transparent electrode only needs to include a light emitting layer, and other configurations are not particularly limited, and are known organic layers that can be used for the organic layer of the organic EL element. Can be used as appropriate. Such an organic layer only needs to include at least one light emitting layer, and may be a laminate of a light emitting layer and various organic thin film layers other than the light emitting layer. The organic thin film layer other than the light emitting layer is not particularly limited as long as it can be used for an organic EL element, and examples thereof include a hole transport layer, an electron transport layer, an anode buffer layer, and a hole. Examples thereof include a blocking layer, an electron blocking layer, and a cathode buffer layer (a cathode buffer layer when the content of the organic material is 50% by mass or more: except for an inorganic layer formed of a metal-based material). In addition, the hole transport layer or the electron transport layer may also serve as the light emitting layer. In this case, the organic layer between the transparent electrode and the metal electrode has a two-layer structure (hole transport layer / electron transport layer). The one layer may function as a light emitting layer.

More specifically, in the embodiment shown in FIG. 1, the organic layer 13 has the following configuration (A):
(A) Hole transport layer 131 / light emitting layer 132 / electron transport layer 133 (hereinafter, the symbol “/” indicates that they are stacked).
In the present invention, the organic layer is appropriately laminated with a layer made of a known organic material such as an anode buffer layer, a hole blocking layer, and an electron blocking layer as the other layer in the present invention. In addition, the light emitting layer in the organic layer may be composed of two layers, ie, a first light emitting layer and a second light emitting layer, each having a different type of host material.

  Thus, when an organic layer contains layers other than a light emitting layer (layer consisting of organic materials other than a light emitting layer), such other layers (hole transport layer, electron transport layer, anode buffer layer, hole) Concavities and convexities formed on the surface of the surface facing the metal electrode of the blocking layer, electron blocking layer, cathode buffer layer (cathode buffer layer when formed of an organic material, etc.) are 10 nm or more in thickness. In some cases, it is preferable to have the same characteristics as the unevenness formed on the surfaces of the hole transport layer, the light emitting layer, and the electron transport layer described in the embodiment shown in FIG. In addition, when such an organic layer is less than 10 nm, the thickness of the layer is thin. Basically, by laminating by a vapor deposition method, a sputtering method or the like, the surface of the object to be laminated (stacked object) is formed. In the present invention, since the ratio of change in the uneven shape characteristics tends to be low at the time of stacking, it is possible to laminate while maintaining the formed uneven shape characteristics sufficiently. When the thickness of each layer is 10 nm or more, it is preferable to have the same characteristics as the unevenness formed on the surfaces of the hole transport layer, the light emitting layer, and the electron transport layer described in the embodiment shown in FIG. It is said. Further, in the embodiment shown in FIG. 1, the unevenness formed on the surface of the surface facing the metal electrode of all layers in the organic layer (all layers regardless of the thickness of those layers) in the organic layer. It is more preferable to have the same characteristics as the unevenness formed on the surfaces of the hole transport layer, the light emitting layer, and the electron transport layer described. That is, any unevenness formed on the surface of the surface facing the metal electrode of each layer (more preferably, all layers in the organic layer regardless of the thickness) whose thickness in the organic layer is 10 nm or more The standard deviation (σ) of the depth distribution is preferably 15 to 50 nm, and the change rate of the standard deviation of the unevenness depth distribution with respect to the standard deviation of the depth distribution of the first unevenness is + 15% to It is preferably -15%. Note that the preferred range of the standard deviation (σ) of the unevenness distribution of the other layers and the rate of change of the standard deviation is the depth of the unevenness of the hole transport layer, the light emitting layer, and the electron transport layer. This is the same range as the preferred range of the standard deviation (σ) of the height distribution and the rate of change of the standard deviation. Further, in such other layers, from the viewpoint of achieving the standard deviation (σ) and the standard deviation change rate in the above-mentioned range, the material constituting the layer has a glass transition temperature (Tg) of 70 ° C. to An organic material at 300 ° C. is preferred. By forming the glass transition temperature (Tg) of the material for forming such another layer in the range of 70 ° C. to 300 ° C., it is possible to more efficiently form a layer having unevenness with high followability to the first unevenness. Accordingly, it is possible to more efficiently form the unevenness having the standard deviation (σ) and the standard deviation change rate within the above-mentioned range in each layer. In addition, the suitable range of the glass transition temperature (Tg) of the material of such another layer is the same range as the material of the above-mentioned hole transport layer. Moreover, it is preferable that all the unevenness | corrugations formed in the surface of the surface facing the metal electrode of all the layers in an organic layer have the characteristic similar to the characteristic (for example, uneven | corrugated height etc.) of a 1st unevenness | corrugation.

  The configuration of the organic EL device of the present invention is not particularly limited as described above, but the organic layer further includes a hole transport layer and an electron transport layer, and the light emitting layer is phosphorescent. A layer containing a material and a host material is preferred. Thus, as the organic EL element of the present invention, for example, the organic EL element of the embodiment as shown in FIG. 1 above, in which the light emitting layer is a layer containing a phosphorescent material and a host material is preferable. .

Moreover, as a specific example of other suitable embodiment of the organic EL element of this invention, the organic layer 13 as shown in FIG. 10, for example is the following structure (B):
(B) Hole transport layer 131 / light emitting layer 132 / hole blocking layer 134 / electron transport layer 133
An organic EL element having a layered structure represented by the following, and further comprising a cathode buffer layer (electron injection layer: inorganic layer) 16 made of a metal-based material between the organic layer 13 and the metal electrode 14. Is mentioned.

  As materials for the hole transport layer 131, the light emitting layer 132, and the electron transport layer 133, those described in the embodiment shown in FIG.

  As a constituent material of the hole blocking layer 134, a known material can be used as appropriate, and for example, BCP (Tg: 83 ° C.) or the like can be used. The hole blocking layer is structurally the same as the electron transport layer used in a normal organic EL element, but its function leaks from the light emitting layer to the cathode side rather than the electron transport function. It is named as a hole blocking layer because it has a powerful function of blocking the movement of the metal, and can be interpreted as a kind of electron transport layer. By using such a hole blocking layer 134, light can be emitted more efficiently. As described above, since the material constituting the organic layer is preferably an organic material at 70 ° C. to 300 ° C., the constituent material of the hole blocking layer 134 also has a glass transition temperature (Tg) of 70 ° C. to 300 ° C. It is preferable that it is an organic material of ° C.

  The thickness of the hole blocking layer 134 is preferably 1 to 50 nm. Also in the case of manufacturing such a hole blocking layer 134, it is preferable to stack the hole blocking layer 134 so that the shape of the first unevenness is maintained. From such a viewpoint, it is preferable to employ a vapor deposition method or a sputtering method as a method of manufacturing the hole blocking layer 134.

As a material of the cathode buffer layer (electron injection layer: inorganic layer) 16 made of a metal-based material, metal fluorides such as lithium fluoride (LiF) and Li ₂ O ₃ , high activity such as Ca, Ba, and Cs are used. Alkaline earth metals can be used. In addition, the content of inorganic materials (metal compounds other than metals and organometallic complexes (metal oxides, hydroxides, halides, nitrates, sulfates, carbonates, etc.)) is 50% by mass or more. The layer which becomes. The thickness of the cathode buffer layer 16 made of such a metal-based material is preferably in the range of 0.1 to 10 nm. Also in the case of manufacturing such a cathode buffer layer 16, it is preferable to stack each of these layers so that the shape of the first unevenness is maintained. It is preferable to adopt the method. The cathode buffer layer 16 made of a metal-based material is a layer made of a metal or a metal compound and is basically a thin layer. Therefore, the cathode buffer layer 16 can be laminated by vapor deposition, sputtering, or the like. It is possible to perform the lamination while sufficiently maintaining the characteristics of the uneven shape formed on the surface of the object to be laminated (laminated object). Further, also in the cathode buffer layer 16 made of a metal-based material, the unevenness formed on the surface of the surface facing the metal electrode preferably has a standard deviation (σ) of the unevenness depth distribution of 15 to 50 nm. Moreover, it is preferable that the change rate of the standard deviation of the unevenness depth distribution with respect to the standard deviation of the first unevenness depth distribution is + 15% to −15%.

Furthermore, as another preferred embodiment of the organic EL device of the present invention, the organic layer further includes a hole transport layer and an electron transport layer, and the light emitting layer contains a phosphorescent material and a host material. As an organic EL element having a layer structure, for example, as shown in FIG. 11, the organic layer has the following structure (C):
(C) Hole transport layer 131 / first light emitting layer 132 (a) / second light emitting layer 132 (b) / electron transport layer 133
And an organic EL element having a cathode buffer layer 16 made of a metal-based material.

  As such a 1st light emitting layer 132 (a) and a 2nd light emitting layer 132 (b), the kind of host material should just differ in the light emitting layers 132 (a) and (b), respectively. As the host material that can be used for the first light-emitting layer 132 (a) and the second light-emitting layer 132 (b), the materials described as the material of the light-emitting layer can be appropriately used. Note that the surface shape (unevenness) of the two light emitting layers has the same characteristics as the light emitting layer 132 described above.

  Further, in the organic EL element having the laminated structure as shown in FIG. 11, the same kind of organic material is used for the material constituting the hole transport layer 131 and the host material of the first light emitting layer 132 (a). (For example, the case where both materials are TCTA may be mentioned.) The same type of organic material is used for the host material of the second light emitting layer 132 (b) and the material constituting the electron transport layer 133. (For example, the case where both materials are TPBi) is preferable. As described above, the same kind of organic material is used as the material used for the material constituting the hole transport layer 131 and the host material of the first light emitting layer 132 (a) while the light emitting layer has a two-layer structure. By using the same type of organic material for the host material of the two light emitting layers 132 (b) and the material constituting the electron transporting layer 133, the hole transporting layer 131, the light emitting layer 132 (a), and The interface between the electron transport layer 133 and the light emitting layer 132 (b) is substantially eliminated, and a decrease in efficiency due to a decrease in energy barrier and carrier mobility at the interface can be suppressed. In the organic EL element using phosphorescence emission, holes are stored between the light emitting layer and the electron transport layer (for example, in the case where a hole blocking layer is provided, the interface between the light emitting layer and the hole blocking layer). Alternatively, if electrons accumulate between the light emitting layer and the hole transport layer (for example, the interface between the light emitting layer and the electron blocking layer when an electron blocking layer is provided), recombination of electrons and holes occurs there. Therefore, the triplet excited state is likely to disappear, and the roll-off phenomenon is likely to occur. In order to suppress such a roll-off phenomenon and prevent the disappearance of the triplet excited state, the recombination region of carriers is made wide and the recombination of electrons and holes at the interface of the light emitting layer is minimized (minimization). It is effective to do. From this point of view, the same type of organic material is used for the material used for the hole transport layer 131 and the host material of the first light emitting layer 132 (a), and the second light emitting layer 132 (b It is preferable to use the same type of organic material as the material used for the host material and the material constituting the electron transport layer 133.

Further, as another embodiment of the organic EL element of the present invention, for example, the organic layer 13 has the following configurations (D) to (K):
(D) Hole transport layer / electron blocking layer / light emitting layer / electron transport layer (E) hole transport layer / electron blocking layer / light emitting layer / hole blocking layer / electron transport layer (F) anode buffer layer (holes) Injection layer) / hole transport layer / electron blocking layer / light emitting layer / electron transport layer (G) anode buffer layer (hole injection layer) / hole transport layer / electron blocking layer / light emitting layer / hole blocking layer / electron Transport layer (H) Hole transport layer / electron blocking layer / light emitting layer / electron transport layer / cathode buffer layer made of organic material (I) hole transport layer / electron blocking layer / light emitting layer / hole blocking layer / electron transport Layer / cathode buffer layer made of organic material (J) anode buffer layer (hole injection layer) / hole transport layer / electron blocking layer / light emitting layer / electron transport layer / cathode buffer layer made of organic material (K) anode buffer Layer (hole injection layer) / hole transport layer / electron blocking layer / light emitting layer / hole blocking layer / electron transport layer / present Organic EL element or the like having a layered structure represented by the cathode buffer layer made of a material can also be mentioned.

  As a constituent material of such an electron blocking layer, a known material can be appropriately used. For example, examples of a material used for the electron blocking layer include TCTA and Irppz. The electron blocking layer is structurally the same as the hole transport layer used in ordinary organic EL elements, but its function leaks from the light emitting layer to the anode side rather than the hole transport function. It is named as an electron blocking layer because it has a powerful function of blocking the movement of electrons, and can also be interpreted as a kind of hole transport layer. In the case where a phosphorescent material is used for the light emitting layer, phosphorescence emission can be performed more efficiently by using such an electron blocking layer. The thickness of such an electron blocking layer is preferably 1 to 50 nm. When manufacturing such an electron blocking layer, it is preferable to laminate so as to maintain the shape of the first unevenness, and it is preferable to employ a vapor deposition method or a sputtering method as the lamination method.

  Moreover, as a material of such an anode buffer layer (hole injection layer), a known material can be appropriately used, and examples thereof include organic materials such as copper phthalocyanine and PEDOT. The thickness of such an anode buffer layer is preferably 1 to 100 nm. Furthermore, when manufacturing such an anode buffer layer, it is preferable to laminate | stack so that the shape of the 1st unevenness | corrugation may be maintained, and it is preferable to employ | adopt a vapor deposition method and a sputtering method as the lamination | stacking method.

  Furthermore, the cathode buffer layer is formed by co-evaporating an organic material such as Bphen, BCP, TBBPhen with an alkali metal compound, an alkali metal, an alkaline earth metal compound, an organic compound doped with an alkaline earth metal, etc. Good. In addition, it is preferable that Tg is in the range of 70 degreeC-300 degreeC for the organic material used in this case. Further, the thickness of such a cathode buffer layer is preferably 1 to 50 nm. Thus, when manufacturing the cathode buffer layer as one of the organic layers, it is preferable that the first unevenness is maintained and the layers are preferably stacked. As the stacking method, vapor deposition or sputtering is adopted. It is preferable.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on a reference example, an Example, and a comparative example, this invention is not limited to a following example.

  First, the measurement method of the uneven | corrugated shaped characteristic formed in each layer of the organic EL element obtained by each reference example, each Example, and each comparative example is demonstrated.

<Measurement method of uneven shape characteristics>
In the measurement method of the concavo-convex shape, first, the first concavo-convex formed on the diffraction grating and the surface facing the metal electrode of the transparent electrode (surface opposite to the surface facing the diffraction grating) are formed. Unevenness, unevenness formed on the surface of each layer of the organic layer facing the metal electrode (surface opposite to the surface facing the diffraction grating), unevenness formed on the surface of the metal electrode facing the organic layer Regarding the uneven shape, an atomic force microscope (scanning probe microscope with an environmental control unit manufactured by SII Nanotechnology, Inc., “Nonavi II station / E-sweep”) is used for an arbitrary measurement area of 3 μm square (vertical 3 μm, horizontal 3 μm). ]) Using the following analysis conditions:
Measurement mode: Dynamic force mode Cantilever: SI-DF40 (material: Si, lever width: 40 μm, tip diameter: 10 nm)
Measurement atmosphere: Measurement temperature in air: 25 ° C
The unevenness analysis image (SPM image) regarding each uneven shape was obtained. In addition, the uneven | corrugated uneven | corrugated shape formed in the surface facing the organic layer of a metal electrode is an adhesive tape (the product name "Scotch Mending Adhesive made by Sumitomo 3M Co., Ltd.") on the outer surface of the metal electrode of the obtained organic EL element. After attaching the “tape” etc., only the metal electrode is peeled off from the organic layer using the adhesive tape under the atmospheric conditions and room temperature (25 ° C.) conditions, and the surface of the metal electrode on the adhesive tape is SPM. Evaluated with a statue.

  Next, with respect to 65536 points (256 vertical points × 256 horizontal points) in the measurement region using the SPM images of each uneven shape, the height from the surface of the transparent support substrate 10 among all the measurement points. Is determined as a reference plane (horizontal plane) including the measurement point and parallel to the surface of the transparent support substrate 10, and the depth value from the reference plane (the transparent support substrate 10 at the measurement point). The difference between the height value from the subtracted height from the transparent support substrate 10 at each measurement point and the unevenness depth data is used as a measurement device (for example, product name “E-” manufactured by SII Nano Technology Co., Ltd.). automatically calculated by the software in “sweep”). And based on such unevenness depth data, the above formulas (I) and (II) are calculated, and the average value (m) of each unevenness depth distribution and the standard deviation of each unevenness depth distribution are calculated. (Σ) was determined. Moreover, based on the data of such unevenness, the median value (M) and kurtosis (k) of the unevenness distribution were also obtained. In addition, the measuring method of the median value (M) and kurtosis (k) of uneven | corrugated depth distribution is the measuring method of the median value (M) and kurtosis (k) of uneven | corrugated depth distribution of the above-mentioned diffraction grating 11. It was calculated | required by employ | adopting the same method.

  Further, using the obtained SPM image of the concavo-convex shape (first concavo-convex shape) of the diffraction grating, the SPM image is subjected to flat processing including first-order inclination correction and then subjected to two-dimensional fast Fourier transform processing. A Fourier transform image was obtained. And based on such an unevenness | corrugation analysis image and a Fourier-transform image, the average height of the unevenness | corrugation of a diffraction grating, the average pitch of an unevenness | corrugation, and the pattern of the Fourier-transform image were measured. In addition, the average height of the unevenness | corrugation of a diffraction grating and the average pitch of an unevenness | corrugation were made into the average value of the height and distance of 100 unevenness | corrugations.

(Reference Example 1)
A structure in which a transparent support substrate / diffraction grating / transparent electrode / hole transport layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer / metal electrode are stacked in this order (see FIG. 10). An organic EL element having a configuration in which the optical member 15 is removed from the organic EL element of the illustrated embodiment was manufactured.

<Preparation process of mold for forming diffraction grating>
First, the block copolymer (A) used in the step of preparing the mother mold (mold) will be described.

[Block copolymer (A)]
Block copolymer of PS and PMMA (manufactured by Polymer Source),
Mn of PS segment = 868,000,
PMMA segment Mn = 857,000,
Block copolymer Mn = 1,725,000
Volume ratio of PS segment to PMMA segment (PS: PMMA) = 53: 47,
Molecular weight distribution (Mw / Mn) = 1.30,
PS segment Tg = 96 ° C.
Tg of the PMMA segment = 110 ° C.

As such a block copolymer (A), polystyrene (hereinafter abbreviated as “PS” where appropriate) is used as the first polymer segment, and polymethyl methacrylate (hereinafter “PMMA” as appropriate) is used as the second polymer segment. A block copolymer manufactured by Polymer Source having abbreviated) was used. The volume ratio (first polymer segment: second polymer segment) of the first and second polymer segments in the block copolymer (A) is such that the density of polystyrene is 1.05 g / cm ³ , It was calculated assuming that the density of methyl methacrylate was 1.19 g / cm ³ . The number average molecular weight (Mn) and weight average molecular weight (Mw) of the polymer segment or polymer are gel permeation chromatography (manufactured by Tosoh Corporation, model number “GPC-8020”, TSK-GEL SuperH1000, SuperH2000, SuperH3000, and SuperH4000 in series. Measured by using a device connected to The glass transition point (Tg) of the polymer segment is determined by using a differential scanning calorimeter (manufactured by Perkin-Elmer, product name “DSC7”) at a temperature increase rate of 20 ° C./min for a temperature range of 0 to 200 ° C. Measurement was performed while raising the temperature. The solubility parameters of polystyrene and polymethylmethacrylate are 9.0 and 9.3, respectively (see Chemical Handbook, Application, 2nd revised edition).

  Next, the preparation process of the master die (mold) for forming the diffraction grating employed in Reference Example 1 will be described. That is, first, 150 mg of the block copolymer (A) and 38 mg of polyethylene glycol 4,000 (Mw = 3000, Mw / Mn = 1.10) made by Tokyo Chemical Industry as polyethylene oxide were added with toluene in a total amount of 10 g. Then, the mixture was dissolved and filtered through a membrane filter having a pore size of 0.5 μm to obtain a block copolymer solution. Next, the block copolymer solution thus obtained was spin-coated on a polyphenylene sulfide film (trade name “Torellina” manufactured by Toray Industries, Inc.) as a base material with a film thickness of 200 to 250 nm. Applied. Such spin coating was performed at a rotational speed of 500 rpm for 10 seconds, and subsequently at 800 rpm for 30 seconds. Thereafter, the thin film coated by spin coating was left to dry at room temperature for 10 minutes.

  Next, the substrate on which the thin film was formed was heated in an oven at 170 ° C. for 5 hours (first heating step). Unevenness was observed on the surface of the thin film after heating, and it was found that the block copolymer constituting the thin film was micro-layer separated. In addition, when the cross section of the thin film was observed with the transmission electron microscope (TEM) (H-7100FA by Hitachi, Ltd.), it was confirmed from the image of the cross section that the micro layer was separated.

Next, the thin film after the first heating step was etched as follows to selectively decompose and remove PMMA from the block copolymer layer on the substrate. In such a decomposition and removal step, first, the thin film was irradiated with ultraviolet rays at an irradiation intensity of 30 J / cm ² using a high-pressure mercury lamp. Subsequently, the thin film was immersed in acetic acid to selectively decompose and remove PMMA, washed with ion-exchanged water, and then dried. In addition, it is measured by a transmission electron microscope (TEM) that an uneven pattern which is clearly deeper than the unevenness appearing on the surface of the thin film by the first heat treatment is formed on the substrate by such a decomposition and removal process. It was confirmed by.

  Next, a heat treatment (second heating step) for 1 hour was performed in an oven at 140 ° C. on the base material on which the uneven pattern formed by the etching treatment was formed. It was confirmed by measurement with a transmission electron microscope (TEM) that the side surface of the convex portion became smoother by such a second heating step and was deformed into a so-called chevron structure.

Next, a thin nickel layer of 10 nm was formed as a current seed layer by sputtering on the surface of the thin film on which the uneven pattern after the second heating step was formed. Next, the base material with a thin film on which such a nickel layer is formed is placed in a nickel sulfamate bath, and electroformed (maximum current density 0.05 A / cm ² ) at a temperature of 50 ° C. to thicken the nickel. Deposited to 250 μm, an electroplating layer (metal layer) was formed on the nickel layer (seed layer). The nickel electroformed body thus formed (a nickel layer as an electroplating layer laminated on a nickel layer as a seed layer) is mechanically removed from a substrate with a thin film on which the concavo-convex pattern is formed. Peeled off. Next, the nickel electroformed body peeled from the base material in this manner was immersed in Chemisole 2303 manufactured by Nippon CB Chemical Co., Ltd. and washed with stirring at 50 ° C. for 2 hours. Then, the acrylic UV curable resin is applied to the nickel electroformed body, cured, and peeled three times to remove the polymer component adhering to the surface of the electroformed body, and the surface is uneven. A mold (M-1) for forming a diffraction grating made of the formed nickel electroformed body was obtained. When the cross section of the diffraction grating forming mold (M-1) thus obtained was observed with a scanning electron microscope (FE-SEM: S4800, manufactured by Hitachi, Ltd.), the unevenness of the nickel electroformed body was smooth. It was found that the convex part had a smooth chevron shape.

  Next, such a mold (M-1) for forming a diffraction grating was immersed in HD-2101TH manufactured by Daikin Chemicals Sales Co., Ltd. for about 1 minute, dried, and then allowed to stand overnight. On the next day, the diffraction grating forming mold (M-1) was immersed in HDTH manufactured by Daikin Chemicals Sales Co., Ltd., and subjected to ultrasonic treatment for about 1 minute. In this manner, the surface of the first mold (M-1) for forming the diffraction grating was subjected to a mold release treatment.

Next, a second mold (M-2) for forming a diffraction grating was manufactured using the first mold (M-1) for forming a diffraction grating. That is, a fluorine-based UV curable resin (trade name “NIF” manufactured by Asahi Glass Co., Ltd.) is applied on a PET substrate (Toyobo Cosmoshine A-4100), and the first mold (M-1) made of nickel After pressing, ultraviolet rays were irradiated at 600 mJ / cm ² to cure the fluorine-based UV curable resin, and then the first mold (M-1) was peeled off. Thus, a second mold (M-2) for forming a diffraction grating composed of a UV curable resin film to which the surface shape of the first mold (M-1) was transferred was obtained. The thickness of the UV curable resin to which the surface shape was transferred was 1 μm.

<Diffraction grating formation process>
Using the above-mentioned “second mold (M-2)”, a diffraction grating 11 made of a cured resin was manufactured on a glass substrate (transparent support substrate 10). When manufacturing such a diffraction grating 11, first, a 0.7 mm-thick glass substrate (made of soda lime) is prepared as the transparent support substrate 10, and fluorine-based UV curability is provided on one surface of the glass plate. Resin (trade name “NIF” manufactured by Asahi Glass Co., Ltd.) was applied. Next, while pressing the second mold (M-2) against the surface of the coating film of the fluorine-based UV curable resin, ultraviolet rays are irradiated under the condition of 600 mJ / cm ² to obtain the fluorine-based UV curable resin. Cured. After the fluorine-based UV curable resin was cured in this way, the PET substrate was peeled from the glass substrate. In this way, a diffraction grating (concave / convex layer) made of a cured resin having a first concavo-convex shape onto which the surface shape of the second mold (M-2) was transferred was laminated on the glass substrate. The thickness of the cured resin layer (uneven layer) having the first uneven shape was 1 μm.

A Fourier transform image of the diffraction grating thus obtained is shown in FIG. As is clear from the Fourier transform image shown in FIG. 12, the Fourier transform image shows a circular pattern whose center is the origin where the absolute value of the wave number is 0 μm ⁻¹ , and the circular pattern is It was confirmed that 90% or more of the bright spots constituting the Fourier transform image exist in a region where the absolute value of the wave number is in the range of 10 μm ⁻¹ or less.

Moreover, the average value of the unevenness distribution (m), the standard deviation of the unevenness depth distribution (σ), the average height of the unevenness of the diffraction grating, and the average of the unevenness obtained from the unevenness analysis image of the surface of the diffraction grating The median value (M) of the distribution of pitch, unevenness depth, and kurtosis (k) of unevenness are described below. The measuring method is as described above.
Average value of uneven depth distribution (m): 50.3 nm
Standard deviation (σ) of uneven depth distribution: 19.3 nm
Average height of irregularities of diffraction grating: 71.5 nm
Average pitch of irregularities: 375 nm
Median value of uneven depth distribution (M): 49.6
Irregularity kurtosis (k): -0.15.

<Organic EL element formation process 1>
Next, using the glass substrate on which the diffraction grating obtained as described above is laminated, on the surface of the diffraction grating on the glass substrate, a transparent electrode [ITO, thickness: 120 nm], a hole transport layer [α -NPD (N, N′-diphenyl-N, N′-bis (3-methylphenyl) -1,1′-diphenyl-4,4′-diamine, Tg: 95 ° C.), thickness: 65 nm], light emitting layer [TCTA (4,4 ′, 4 ″ -tris (carbazol-9-yl) -triphenylamine, Tg: 149 ° C.) to Ir (ppy) ₃ complex (tris (2-phenylpyridinate) iridium (III )) 7.0% by mass, thickness: 30 nm], hole blocking layer (hole blocking layer) [BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline, Tg) : 83 ° C.), thickness: 5 nm], electrons Transport layer [Alq ₃ (8-hydroxyquinoline aluminum, Tg: 175 ° C.), thickness: 60 nm], cathode buffer layer [lithium fluoride (LiF), thickness: 1.5 nm, inorganic layer] made of metal-based material and metal The electrodes [aluminum, thickness: 50 nm] are laminated in such a manner that the shape of the first unevenness formed on the surface of the diffraction grating is maintained, and each glass substrate / diffraction grating / transparent electrode / hole transport is laminated. Organic layers laminated in order of layer / light emitting layer / hole blocking layer / electron transport layer / cathode buffer layer (inorganic layer) / metal electrode so that the size and area of the light emitting pixel are 3 mm long × 3 mm wide and 9 mm ² respectively. A laminate for an EL element was obtained. In addition, the lamination process of each layer is as follows. That is, first, the transparent electrode was laminated by a sputtering method. The transparent electrode was exposed to oxygen plasma after film formation to increase the work function (radical treatment). Moreover, the hole transport layer was laminated | stacked by the vacuum evaporation method. Furthermore, the light emitting layer was laminated | stacked by the co-evaporation method using TCTA and Ir (ppy) ₃ , adjusting so that the introduction amount of Ir (ppy) _{3 in} a layer might be 7 mass%. Further, the hole blocking layer (hole blocking layer), the electron transporting layer, the cathode buffer layer (lithium fluoride layer), and the metal electrode were laminated by a vacuum deposition method. In all the reference examples, examples, and comparative examples thereafter, the size and area of the light emitting pixel are 3 mm long × 3 mm wide and 9 mm ² . When laminating each layer in this way, after forming each layer of the transparent electrode, the hole transport layer, the light emitting layer, and the electron transport layer, the concavo-convex shape of the surface opposite to the surface facing the diffraction grating of those layers is formed. Each characteristic was measured, and the standard deviation (σ) of the unevenness depth of each layer and the change rate of the standard deviation of the unevenness depth of each layer with respect to the standard deviation of the first unevenness formed on the surface of the diffraction grating were obtained. . In addition, the characteristic of the unevenness of the surface of the metal electrode facing the diffraction grating is that the SPM image of the surface of the metal electrode on the adhesive tape is obtained by peeling the metal electrode from the organic layer with the adhesive tape after forming the element as described above. We evaluated using. In addition, the change rate of the standard deviation of the unevenness depth of each layer is represented by the following formula:
[Change rate] = {([Standard deviation of depth distribution of unevenness of each layer] − [Standard deviation of depth distribution of first unevenness]) / [Standard deviation of depth distribution of first unevenness]} × 100
Was calculated. The obtained values are shown in Table 1.

  As is clear from the results shown in Table 1, in the organic EL device obtained in Reference Example 1, the surface facing the diffraction grating of each layer of the transparent electrode, the hole transport layer, the light emitting layer, and the electron transport layer is The concave and convex shape of the opposite surface and the concave and convex shape of the surface facing the diffraction grating of the metal electrode both have a standard deviation (σ) of the concave and convex depth in the range of 15 to 50 nm, and The rate of change of the standard deviation of the unevenness depth of each layer with respect to the standard deviation is within the range of + 15% to -15%, and it is confirmed that the film thickness of each of these layers is very uniform. It was. From these results, it was found that the organic EL element obtained in Reference Example 1 satisfies the above-described conditions (A) to (C).

  Moreover, the image of the transmission electron microscope (TEM) of the cross section of the organic EL element obtained in Reference Example 1 is shown in FIGS. From the results shown in FIGS. 13 and 14, in the organic EL element obtained in Reference Example 1, the unevenness of each layer is sufficiently high following the first unevenness formed on the surface of the diffraction grating, It was confirmed that the film thickness uniformity between the electrodes was very high. In addition, for the measurement with a transmission electron micromirror (TEM) having such a cross section, a test piece (ultra thin section) having a thickness of 70 nm was manufactured and used as a measurement sample.

  In addition, when measuring such a cross section, the thickness between the concave portions and the thickness between the convex portions (hole transport layer, light emitting layer, hole blocking layer, electron transport layer) and the entire organic layer in the organic layer ( The portion indicated by the white arrow in FIG. 13 is the thickness between the concave portions of the entire organic layer, and the portion indicated by the white arrow in FIG. 14 is the thickness between the convex portions of the entire organic layer. Two arbitrary points were measured, and the ratio of the average thickness between the concave portions of each layer to the average thickness between the convex portions of each layer ([average value of thickness between concave portions] / [average value of thickness between convex portions] ) Was measured. The obtained results are shown in Table 2.

  As is clear from the results shown in Table 2, it was confirmed that in the organic EL element obtained in Reference Example 1, each layer of the organic layer and the entire film thickness were very uniform.

(Comparative Example 1)
A diffraction grating (uneven layer) was produced on a glass substrate by employing the same method as the diffraction grating forming step employed in Reference Example 1. Next, the same procedure as in Reference Example 1 was performed except that the host material of the light emitting layer was changed from TCTA (Tg: 149 ° C.) to CBP (4,4′-N, N′-dicarbazole-biphenyl, Tg: 65 ° C.). Glass substrate / diffraction grating / transparent electrode (ITO) / hole transport layer (α-NPD) / light emitting layer (CBP: Ir (ppy) ₃ 7.0 mass%) / hole blocking layer (BCP) / electron A laminate for an organic EL device was obtained in which the transport layer (Alq ₃ ) / cathode buffer layer (LiF: inorganic layer) / metal electrode (Al) were laminated in this order.

In this way, the Fourier transform image of the diffraction grating obtained in Comparative Example 1 shows a circular pattern having an approximate center at the origin where the absolute value of the wave number is 0 μm ⁻¹ , as in Reference Example 1. In addition, the circular pattern has 90% or more of bright spots in all the bright spots constituting the Fourier transform image in the region where the absolute value of the wave number is in the range of 10 μm ⁻¹ or less. Was confirmed. Further, the diffraction grating obtained in Comparative Example 1 is the same method as the method employed in Reference Example 1 by the manufacturing method, and the average value (m) of the uneven depth distribution and the uneven depth distribution. The characteristics such as the standard deviation (σ), the average height of the unevenness of the diffraction grating, the average pitch of the unevenness, the median value of the distribution of the unevenness depth (M), and the kurtosis (k) of the unevenness are the same as in Reference Example 1. It had the characteristics of

  In Comparative Example 1, when laminating each layer, after forming each layer of the transparent electrode, the hole transport layer, the light emitting layer, and the electron transport layer, the surface opposite to the surface facing the diffraction grating of those layers Measure the characteristics of the concavo-convex shape of each layer, and the standard deviation (σ) of the concavo-convex depth of each layer and the change rate of the standard deviation of the concavo-convex depth of each layer relative to the standard deviation of the first concavo-convex formed on the surface of the diffraction grating I asked for each. Further, in the same manner as in Reference Example 1, the unevenness of each layer with respect to the standard deviation (σ) of the unevenness depth of the surface facing the diffraction grating of the metal electrode and the standard deviation of the first unevenness formed on the surface of the diffraction grating The rate of change of the standard deviation of depth was also obtained. The obtained values are shown in Table 3.

  As is clear from the results shown in Table 3, in the organic EL device obtained in Comparative Example 1, the standard deviation (σ) of the unevenness depth of the light emitting layer is outside the range of 15 to 50 nm. The change rate of the standard deviation of the unevenness depth of the light emitting layer with respect to the standard deviation of the first unevenness is −24.0%, and it is confirmed that the followability to the first unevenness is lowered in the light emitting layer. It was done. Also, in the electron transport layer and metal electrode laminated after the light emitting layer is laminated, the standard deviation (σ) value of those layers and the standard deviation of the irregularity depth of those layers with respect to the standard deviation of the first irregularity From the value of the rate, it was found that the followability to the first unevenness was lowered due to the change in the uneven structure in the light emitting layer. From these results, in Comparative Example 1, it was confirmed that in the light emitting layer (CBP), a large amount of material was deposited in the recesses, the uneven shape was smoothed and blunted, and the depth of the recesses was shallow. .

  Moreover, the cross-sectional measurement of the organic EL element obtained in Comparative Example 1 was performed in the same manner as in Reference Example 1. FIG. 15 shows an image of a transmission electron microscope (TEM) of the cross section of the organic EL element obtained in Comparative Example 1. As is clear from the results shown in FIG. 15, in the organic EL element obtained in Comparative Example 1, in the organic layer, the followability with respect to the first unevenness formed on the surface of the diffraction grating is lowered. Compared with the organic EL element obtained in 1, it was found that the film thickness uniformity between the electrodes was low. That is, when comparing the uniformity of the film thickness of each layer of the organic EL element obtained in Reference Example 1 and the organic EL element obtained in Comparative Example 1 from a comparison between FIGS. It was found that the organic EL device obtained in Reference Example 1 has a higher degree of uniformity. 13 to 14 and FIG. 15, in the organic EL element obtained in Comparative Example 1, the thickness between the recesses is thick, the unevenness is smoothed in the organic layer, and the recess is shallow. It was also found that (unevenness is dull).

  In addition, during the cross-sectional measurement, each layer in the organic layer (hole transport layer, light emitting layer, hole blocking layer, electron transport layer) and the thickness between the concave portions and the thickness between the convex portions of the entire organic layer ( The thickness of the portion indicated by the white arrow in FIG. 15 is measured at any two points, and the ratio of the average value of the thickness between the concave portions of each layer to the average value of the thickness between the convex portions of each layer ([recessed portion Mean value of thickness between] / [mean value of thickness between convex parts]). Table 4 shows the obtained results.

  As is clear from the results shown in Table 2 and Table 4, compared with the organic EL element obtained in Reference Example 1, the organic EL element obtained in Comparative Example 1 is composed of each layer of the organic layer and the entire organic layer. It was found that the uniformity of the film thickness was not sufficient. In such a result, considering that the ratio of the average thickness of the unevenness in the light emitting layer is 1.62 times, a material having a Tg lower than 70 ° C. (CBP, Tg: 65 ° C.) is used. It can be seen that when used as a constituent material of the layer, the followability of the unevenness is lowered.

(Comparative Example 2)
A glass substrate / transparent electrode (ITO) was formed in the same manner as in Reference Example 1 except that a glass substrate was used as it was instead of using a glass substrate on which diffraction gratings were laminated in the organic EL element forming step without forming a diffraction grating. / Hole transport layer (α-NPD) / Light emitting layer (TCTA: Ir (ppy) ₃ 7.0% by mass) / Hole blocking layer (BCP) / Electron transport layer (Alq ₃ ) / Cathode buffer layer (LiF) / The laminated body for organic EL elements laminated | stacked in order of the metal electrode (Al) was obtained.

(Comparative Example 3)
A glass substrate / transparent electrode (ITO) was formed in the same manner as in Comparative Example 1 except that a glass substrate was used as it was instead of using a glass substrate on which diffraction gratings were laminated in the organic EL element forming step without forming a diffraction grating. / Hole transport layer (α-NPD) / Light emitting layer (CBP: Ir (ppy) ₃ 7.0 mass%) / Hole blocking layer (BCP) / Electron transport layer (Alq ₃ ) / Cathode buffer layer (LiF) / The laminated body for organic EL elements laminated | stacked in order of the metal electrode (Al) was obtained.

[Measurement of Luminous Efficiency of Organic EL Elements Obtained in Reference Example 1 and Comparative Examples 1-3]
The luminous efficiency of the organic EL elements obtained in Reference Example 1 and Comparative Examples 1 to 3 was measured by the following method. That is, a voltage is applied to the organic EL element, and the applied voltage (V: unit V) and the current flowing through the organic EL element (I: unit A) are measured with an applied measuring instrument (manufactured by Advantest Corporation, model number: R6244). The luminous flux (L: unit: lm) was measured with a total luminous flux measuring apparatus (Spectra Corp., Solid Lambda CCD UV-NIR). Based on the measured values of the applied voltage (V), current (I), and total luminous flux (L) thus obtained, the current efficiency (CE, unit: cd) when the front luminance (L ′) is 1000 cd / m ^2. / A) is calculated using the following formula (F2), and the following formula (F3) is calculated for the power efficiency (PE, unit: Lm / W) at the time of front luminance (L ′) 1000 cd / m ^2. Used to calculate. Note that the front luminance (L ′: unit cd / m ² ) assumes that the angular distribution of element emission is Lambertian, and the value of the light emitting element area (S: unit m ² ) and the total luminous flux according to the formula (F1). It calculated | required and converted from the value of (L: unit lm).
(Luminance Luminance L ′) = L / π / S (F1)
(Current efficiency) = (L ′ / I) (F2)
(Power efficiency) = (L / I / V) (F3).

  Table 5 shows the current efficiency (CE) and power efficiency (PE) of the organic EL elements obtained in Reference Example 1 and Comparative Example 2 among the measurement results of luminous efficiency. The organic EL elements obtained in Reference Example 1 and Comparative Example 2 have different configurations in terms of the presence / absence of a diffraction grating and the presence / absence of a concavo-convex structure of each layer. The materials are the same. Moreover, with respect to the current efficiency (CE) and power efficiency (PE) of the organic EL element (using raw glass) obtained in Comparative Example 2, the organic EL element (glass substrate / diffraction grating) obtained in Reference Example 1 was used. Table 5 also shows the results of calculating the ratio (magnification) of improvement in current efficiency (CE) and power efficiency (PE).

  As is clear from the results shown in Table 5, when the organic EL element obtained in Reference Example 1 is compared with the organic EL element obtained in Comparative Example 2, the luminous efficiency is improved by using a diffraction grating. Confirmed to do.

  Next, Table 6 shows the current efficiency (CE) and power efficiency (PE) of the organic EL elements obtained in Comparative Example 1 and Comparative Example 3. The organic EL elements obtained in Comparative Example 1 and Comparative Example 3 have different configurations in terms of the presence / absence of a diffraction grating and the presence / absence of a concavo-convex structure of each layer, but constitute a laminated configuration of other layers and each layer. The materials are the same. Moreover, with respect to the current efficiency (CE) and power efficiency (PE) of the organic EL element (using raw glass) obtained in Comparative Example 3, the organic EL element (glass substrate / diffraction grating) obtained in Comparative Example 1 was used. Table 6 also shows the results of calculating the ratio (magnification) of improvement in current efficiency (CE) and power efficiency (PE).

  As is clear from the results shown in Table 6, when the organic EL element obtained in Comparative Example 1 is compared with the organic EL element obtained in Comparative Example 3, the luminous efficiency is improved by using a diffraction grating. Confirmed to do.

  In addition, from the results shown in Tables 5 and 6, the magnification values of current efficiency (CE) and power efficiency (PE) improved by using a diffraction grating with respect to an organic EL element using only raw glass as a substrate. Compared with Reference Example 1 and Comparative Example 1, the organic EL element obtained in Reference Example 1 uses a diffraction grating and thus does not use a diffraction grating (Comparative Example 2). While the current efficiency (CE) is improved by 1.20 times, in the organic EL element obtained in Comparative Example 1, the magnification of the current efficiency (CE) improved by using the diffraction grating is 1. It was confirmed that the current efficiency of the organic EL element obtained in Reference Example 1 was improved to a sufficiently high level. Moreover, in the organic EL element obtained in Reference Example 1, the power efficiency (PE) is improved by 1.42 times by using the diffraction grating, compared with the case where the diffraction grating is not used (Comparative Example 2). On the other hand, in the organic EL device obtained in Comparative Example 1, the power efficiency (PE) magnification improved by using the diffraction grating is 1.25 times, which is obtained in Reference Example 1. It was confirmed that the power efficiency of the obtained organic EL element was improved at a sufficiently high level. Thus, in the organic EL element obtained in Reference Example 1, it was confirmed that the current efficiency (CE) and power efficiency (PE) were sufficiently improved at a higher level, and the light emission efficiency could be further improved. It was.

  From the comparison result between the organic EL element obtained in Reference Example 1 and the organic EL element obtained in Comparative Example 1, the organic EL element obtained in Reference Example 1 is formed on a metal electrode. The second unevenness has the unevenness depth standard deviation (σ) in the range of 15 to 50 nm, and the change rate of the unevenness depth standard deviation with respect to the first unevenness standard deviation is + 15% to −15. %, And the second unevenness formed on the metal electrode has higher followability with respect to the shape of the first unevenness than that of Comparative Example 1. Uniformity of the entire layer between the metal electrodes is higher, current efficiency (CE) and power efficiency (PE) are more fully improved, and luminous efficiency can be improved to a higher level. I understood. In Reference Example 1, as described above, the surface of the surface opposite to the surface facing the diffraction grating formed on the transparent electrode, the hole transport layer, the light emitting layer, and the electron transport layer. And the unevenness formed on the surface facing the diffraction grating of the metal electrode both have a standard deviation (σ) of the unevenness depth in the range of 15 to 50 nm, and The rate of change of the standard deviation of the concave / convex depth with respect to the standard deviation of the first concave / convex is within the range of + 15% to −15%, and each layer has sufficient followability to the shape of the first concave / convex. It was high, and the uniformity of the film thickness of each layer was sufficiently high.

  Moreover, from the comparison result of the reference example 1 and the comparative example 1, an organic EL element provided with the metal electrode in which the 2nd unevenness | corrugation with high followable | trackability with respect to the 1st unevenness | corrugation was formed (the said conditions (A)-(C) are satisfy | filled. It was found that the organic EL element) can improve the luminous efficiency at a higher level. That is, the diffraction grating satisfying the condition (A) is used in consideration of the fact that the reference example 1 and the comparative example 1 are different only in the type of the host material of the light emitting layer, and other configurations are basically the same. Even if the element does not satisfy the conditions (B) and (C), the effect of improving the light emission efficiency is not necessarily sufficient, and the organic that satisfies all the above conditions (A) to (C). It has been found that the EL element can stably obtain the effect of improving the light emission efficiency at a higher level. In addition, from the result of the organic EL element obtained in Reference Example 1 and Comparative Example 1, a hemispherical lens or the like is further formed on the light extraction surface side of the transparent support substrate of the element that satisfies all the above conditions (A) to (C). It can be seen that an organic EL element having an optical member for extracting light to the outside (organic EL element of the present invention) can achieve very high light extraction efficiency.

Example 1
A diffraction grating (uneven layer) was produced on a glass substrate by employing the same method as the diffraction grating forming step employed in Reference Example 1. Next, instead of performing the organic EL element forming step 1, an organic EL element forming step 2 described later is performed, and an optical member is formed on the other surface of the glass substrate (the surface opposite to the surface on which the diffraction grating is formed). Except for the arrangement of the hemispherical lens, the structure shown in FIG. 11 (optical member 15 (hemispherical lens) / transparent support substrate 10 / diffraction grating 11 / transparent electrode 12 / hole transport layer 131) is the same as in Reference Example 1. An organic EL device having a structure in which / first light emitting layer 132 (a) / second light emitting layer 132 (b) / electron transport layer 133 / cathode buffer layer 16 / metal electrode 14 are stacked in this order was manufactured. In FIG. 11, the element of the embodiment in which a plurality of optical members are arranged is described. However, the configuration of the element of this example is such that the area of the bottom surface of the optical member 15 is smaller than the area of the light emitting pixels. One large hemispherical lens is arranged.

  Further, as a method of arranging a hemispherical lens as the optical member 15 on the other surface of the glass substrate (the surface opposite to the surface on which the diffraction grating is formed), a hemispherical lens having a diameter of 5 mm (manufactured by Edmund) is uncured. The UV curable epoxy resin (trade name “NOA81” manufactured by Norland) was used as an adhesive and laminated on the surface of the glass substrate. Such a hemispherical lens is arranged so that the central portion of the bottom surface of the hemispherical lens overlaps the central portion of the light emitting pixel.

In addition, the Fourier transform image of the diffraction grating obtained in Example 1 shows a circular pattern with the origin at which the absolute value of the wave number is 0 μm ⁻¹ in the same manner as in Reference Example 1, and It is confirmed that 90% or more of the bright spots constituting the Fourier transform image are present in the circular pattern in the region where the absolute value of the wave number is in the range of 10 μm ⁻¹ or less. It was done. In addition, the diffraction grating obtained in Example 1 is the same method as the method employed in Reference Example 1 by the manufacturing method, and the average value (m) of the uneven depth distribution and the uneven depth distribution. The characteristics such as the standard deviation (σ), the average height of the unevenness of the diffraction grating, the average pitch of the unevenness, the median value of the distribution of the unevenness depth (M), and the kurtosis (k) of the unevenness are the same as in Reference Example 1. It had the characteristics of

<Organic EL element formation process 2>
Using a glass substrate on which the diffraction grating is laminated, a transparent electrode [ITO, thickness: 120 nm], a hole transport layer [TCTA (Tg: 149 ° C.), thickness: 35 nm on the surface of the diffraction grating on the glass substrate. ], First light emitting layer [TCTA (Tg: 149 ° C.) containing 7.0 mass% Ir (ppy) ₃ , thickness: 15 nm], second light emitting layer [TPBi (1,3,5-tris ( N-phenylbenzimidazolyl) benzene, Tg: 124 ° C.) containing 7.0% by mass of Ir (ppy) ₃ , thickness: 15 nm], electron transport layer [TPBi (Tg: 124 ° C.), thickness: 50 nm] The first uneven shape formed on the surface of the diffraction grating is a cathode buffer layer [lithium fluoride (LiF), thickness: 1.5 nm] and metal electrode [aluminum, thickness: 50 nm] made of a metal-based material. The glass substrate / diffraction grating / transparent electrode / hole transport layer / first light emitting layer / second light emitting layer / electron transport layer / cathode buffer layer (inorganic layer) / A laminated body for an organic EL device in which metal electrodes were laminated in this order (in the device, the organic layer was a laminated structure of a hole transport layer / first light emitting layer / second light emitting layer / electron transport layer) was obtained. In addition, the lamination process of each layer is as follows. That is, first, the transparent electrode was laminated by a sputtering method. The transparent electrode was exposed to oxygen plasma after film formation to increase the work function (radical treatment). Moreover, the hole transport layer was laminated | stacked by the vacuum evaporation method. Furthermore, the first light emitting layer was laminated by a co-evaporation method using TCTA and Ir (ppy) ₃ while adjusting the amount of Ir (ppy) ₃ introduced in the layer to 7% by mass. . The second light emitting layer was laminated by co-evaporation using TPBi and Ir (ppy) ₃ while adjusting the amount of Ir (ppy) ₃ introduced into the layer to be 7% by mass. . Moreover, the electron carrying layer, the cathode buffer layer (lithium fluoride layer), and the metal electrode were each laminated | stacked by the vacuum evaporation method. When laminating each layer in this way, after forming each layer of the transparent electrode, the hole transport layer, the first light emitting layer, the second light emitting layer, and the electron transport layer, the surface of each layer opposite to the diffraction grating is opposite. Measure the characteristics of the concavo-convex shape of the side surface, the standard deviation of the concavo-convex depth of each layer (σ) and the standard deviation of the concavo-convex depth of each layer relative to the standard deviation of the first concavo-convex formed on the surface of the diffraction grating The change rate of each was calculated | required. Further, in the same manner as in Reference Example 1, the unevenness depth relative to the standard deviation (σ) of the unevenness depth of the surface facing the diffraction grating of the metal electrode and the standard deviation of the first unevenness formed on the surface of the diffraction grating. The rate of change of the standard deviation was also obtained. In addition, the change rate of the standard deviation of the unevenness depth of each layer is represented by the following formula:
[Change rate] = {([Standard deviation of depth distribution of unevenness of each layer] − [Standard deviation of depth distribution of first unevenness]) / [Standard deviation of depth distribution of first unevenness]} × 100
Was calculated. The values obtained are shown in Table 7.

  As is clear from the results shown in Table 7, in the organic EL device obtained in Example 1, it was formed on each layer of the transparent electrode, the hole transport layer, the first light emitting layer, the second light emitting layer, and the electron transport layer. The unevenness formed on the surface opposite to the surface facing the diffraction grating and the unevenness formed on the surface facing the diffraction grating of the metal electrode are both uneven. The standard deviation (σ) of the thickness is in the range of 15 to 50 nm, and the change rate of the standard deviation of the unevenness depth of each layer with respect to the standard deviation of the first unevenness is in the range of + 15% to −15%. It was confirmed that the film thickness of each layer was very uniform. From these results, it was found that the organic EL element obtained in Example 1 satisfies the above-mentioned conditions (A) to (C).

(Reference Example 2)
The transparent support substrate 10 / diffraction grating 11 / transparent electrode 12 / hole transporting layer 131 / first light emitting layer 132 (a) / second, except that the step of arranging the hemispherical lens was not performed. An organic EL device having a structure in which the two light emitting layers 132 (b) / electron transport layer 133 / cathode buffer layer 16 / metal electrode 14 were laminated in this order was manufactured. In addition, the organic EL element obtained in Reference Example 2 satisfied the above-described conditions (A) to (C) as in Example 1.

(Comparative Example 4)
In the same manner as in Example 1, except that the diffraction grating was not formed and the glass substrate was used as it was instead of the glass substrate on which the diffraction grating was laminated in the organic EL element forming step 2, the optical member (hemispherical lens) / 6. Glass substrate / transparent electrode (ITO) / hole transport layer (TCTA) / first light emitting layer (TCTA: Ir (ppy) ₃ 7.0% by mass) / second light emitting layer (TPBi: Ir (ppy) ₃ 0 mass%) / electron transport layer (TPBi) / cathode buffer layer (LiF) / metal electrode (Al) were laminated in this order to obtain an organic EL device.

(Comparative Example 5)
Glass substrate / transparent electrode (ITO) / hole transport layer (TCTA) / first light emitting layer (TCTA: Ir (ppy) ₃ 7.0, except that no hemispherical lens was arranged Mass%) / second light emitting layer (TPBi: Ir (ppy) ₃ 7.0% by mass) / electron transport layer (TPBi) / cathode buffer layer (LiF) / metal electrode (Al) in this order. Got.

[Measurement of Luminous Efficiency of Organic EL Elements Obtained in Example 1, Reference Example 2 and Comparative Examples 4 to 5]
When measuring the luminous efficiencies of the organic EL elements obtained in Example 1, Reference Example 2 and Comparative Examples 4 to 5, the organic EL elements obtained in Reference Example 1 and Comparative Examples 1 to 3 were measured. The current efficiency (CE) and power efficiency (PE) of the organic EL devices obtained in Example 1, Reference Example 2 and Comparative Examples 4 to 5 were determined in the same manner as in Example 1. Table 8 shows the obtained results. Moreover, with respect to the current efficiency (CE) and power efficiency (PE) of the organic EL elements obtained in Reference Example 2 and Comparative Examples 4 to 5, the current efficiency (CE) of the organic EL elements obtained in Example 1 was obtained. Table 8 also shows the results of calculating the ratio (magnification) in which the power efficiency (PE) was improved.

  As is clear from the results shown in Table 8, when the organic EL elements obtained in Example 1 and Reference Example 2 are compared with the organic EL elements obtained in Comparative Example 5, the above-mentioned condition (A) is satisfied. In the organic EL element using the diffraction grating (Example 1, Reference Example 2), the light emission efficiency is sufficiently improved as compared with the organic EL element not using the diffraction grating (Comparative Example 5). confirmed. Moreover, the organic EL element obtained in Example 1 that satisfies the conditions (A) to (C) is compared with the organic EL element obtained in Comparative Example 4 that uses only a hemispherical lens without using a diffraction grating. Thus, it was confirmed that higher luminous efficiency can be achieved by satisfying the conditions (A) to (C). Further, considering the difference between the organic EL elements obtained in Example 1 and Reference Example 2 only in the presence or absence of a hemispherical lens, the above conditions (A) to (C) are satisfied and the light of the glass substrate is satisfied. It has been found that by providing a hemispherical lens on the extraction surface side, the rate of improvement in current efficiency (CE) and power efficiency (PE) becomes higher. Thus, from the results shown in Table 8, the luminous efficiency of the organic EL element is satisfied by satisfying the above conditions (A) to (C) and including an optical member such as a hemispherical lens on the light extraction surface side of the glass substrate. Was confirmed to improve at a higher level.

(Example 2)
A diffraction grating (uneven layer) was produced on a glass substrate by employing the same method as the diffraction grating forming step employed in Reference Example 1. Next, instead of performing the organic EL element forming step 1, an organic EL element forming step 3 described later is performed, and an optical member is formed on the other surface of the glass substrate (the surface opposite to the surface on which the diffraction grating is formed). Optical member (hemispherical lens) / transparent support substrate (glass substrate) / diffraction grating / transparent electrode (ITO) / hole transport layer (TCTA) / light emitting layer in the same manner as in Reference Example 1 except that a hemispherical lens was disposed. An organic EL device having a structure in which (TCTA: Ir (ppy) ₃ 7.0% by mass) / electron transport layer (TpBi) / cathode buffer layer (LiF) / metal electrode (Al) was laminated in this order was produced.

As a method of arranging a hemispherical lens as the optical member 15 on the other surface of the glass substrate (the surface opposite to the surface on which the diffraction grating is formed), a hemispherical lens having a diameter of 5 mm (manufactured by Edmund) is uncured. The UV curable epoxy resin (trade name “NOA81” manufactured by Norland) was used as an adhesive and laminated on the surface of the glass substrate. Such a hemispherical lens was arranged so that the central portion of the bottom surface of the hemispherical lens overlapped with the central portion of the light emitting pixel (vertical 3 mm × horizontal 3 mm, 9 mm ² ).

In addition, the Fourier transform image of the diffraction grating obtained in Example 2 shows a circular pattern whose center is the origin where the absolute value of the wave number is 0 μm ⁻¹ , as in Reference Example 1. And 90% or more of the bright spots constituting the Fourier transform image are present in a region where the circular pattern has an absolute value of the wave number of 10 μm ⁻¹ or less. It was confirmed that there was. Moreover, the diffraction grating obtained in Example 2 is the same method as the method employed in Reference Example 1 by the manufacturing method, and the average value (m) of the uneven depth distribution and the uneven depth distribution. The characteristics such as the standard deviation (σ), the average height of the unevenness of the diffraction grating, the average pitch of the unevenness, the median value of the distribution of the unevenness depth (M), and the kurtosis (k) of the unevenness are the same as in Reference Example 1. It had the characteristics of

<Organic EL element formation process 3>
Using a glass substrate on which the diffraction grating is laminated, a transparent electrode [ITO, thickness: 120 nm], a hole transport layer [TCTA (Tg: 149 ° C.), thickness: 35 nm on the surface of the diffraction grating on the glass substrate. ], A light emitting layer [TCTA (Tg: 149 ° C.) containing 7.0% by mass of Ir (ppy) ₃ , thickness: 15 nm], electron transport layer [TPBi (Tg: 124 ° C.), thickness: 65 nm], A cathode buffer layer [lithium fluoride (LiF), thickness: 1.5 nm] and a metal electrode [aluminum, thickness: 50 nm] made of a metal-based material are formed on the surface of the diffraction grating. As maintained, organic layers were laminated in the order of glass substrate / diffraction grating / transparent electrode / hole transport layer / light emitting layer / electron transport layer / cathode buffer layer (inorganic layer) / metal electrode. Laminate for L element (in the element, the organic layer laminated structure of hole transport layer / light emitting layer / electron transport layer) was obtained. In addition, the lamination process of each layer is as follows. That is, first, the transparent electrode was laminated by a sputtering method. The transparent electrode was exposed to oxygen plasma after film formation to increase the work function (radical treatment). Moreover, the hole transport layer was laminated | stacked by the vacuum evaporation method. Furthermore, the light emitting layer was laminated | stacked by the co-evaporation method using TCTA and Ir (ppy) ₃ , adjusting so that the introduction amount of Ir (ppy) _{3 in} a layer might be 7 mass%. Moreover, the electron carrying layer, the cathode buffer layer (lithium fluoride layer), and the metal electrode were each laminated | stacked by the vacuum evaporation method. When laminating each layer in this way, after forming each layer of the transparent electrode, the hole transport layer, the light emitting layer, and the electron transport layer, the concavo-convex shape of the surface opposite to the surface facing the diffraction grating of those layers is formed. Each characteristic was measured, and the standard deviation (σ) of the unevenness depth of each layer and the change rate of the standard deviation of the unevenness depth of each layer with respect to the standard deviation of the first unevenness formed on the surface of the diffraction grating were obtained. . Also find the standard deviation (σ) of the unevenness depth of the surface facing the diffraction grating of the metal electrode and the rate of change of the standard deviation of the unevenness depth with respect to the standard deviation of the first unevenness formed on the surface of the diffraction grating. It was. In addition, the change rate of the standard deviation of the unevenness depth of each layer is represented by the following formula:
[Change rate] = {([Standard deviation of depth distribution of unevenness of each layer] − [Standard deviation of depth distribution of first unevenness]) / [Standard deviation of depth distribution of first unevenness]} × 100
Was calculated. Table 9 shows the obtained values.

  As is clear from the results shown in Table 9, in the organic EL device obtained in Example 2, the unevenness (diffraction grating) formed in each layer of the transparent electrode, the hole transport layer, the light emitting layer, and the electron transport layer. The unevenness formed on the surface opposite to the surface opposite to the surface and the unevenness formed on the surface facing the diffraction grating of the metal electrode are both standard deviations of the unevenness depth (σ) Is within the range of 15 to 50 nm, and the change rate of the standard deviation of the unevenness depth of each layer with respect to the standard deviation of the first unevenness is within the range of + 15% to −15%, and the film of each layer It was confirmed that the thickness was very uniform. From these results, it was found that the organic EL device obtained in Example 2 satisfies the above-described conditions (A) to (C).

(Reference Example 3)
Transparent support substrate (glass substrate) / diffraction grating / transparent electrode (ITO) / hole transport layer (TCTA) / light emitting layer (TCTA) in the same manner as in Example 2 except that the step of arranging the hemispherical lens was not performed. : Ir (ppy) ₃ 7.0% by mass) / electron transport layer (TpBi) / cathode buffer layer (LiF) / organic electrode (Al) was laminated in this order to produce an organic EL device. In addition, the organic EL element obtained in Reference Example 3 satisfied the above-described conditions (A) to (C) as in Example 2.

(Comparative Example 6)
In the same manner as in Example 2, except that the diffraction grating was not formed and the glass substrate was used as it was instead of the glass substrate on which the diffraction grating was laminated in the organic EL element forming step 3, the optical member (hemispherical lens) / Glass substrate / transparent electrode (ITO) / hole transport layer (TCTA) / light emitting layer (TCTA: Ir (ppy) ₃ 7.0% by mass) / electron transport layer (TPBi) / cathode buffer layer (LiF) / metal electrode An organic EL element laminated in the order of (Al) was obtained.

(Comparative Example 7)
Glass substrate / transparent electrode (ITO) / hole transport layer (TCTA) / light emitting layer (TCTA: Ir (ppy) ₃ 7.0% by mass, except that no hemispherical lens was arranged ) / Electron transport layer (TPBi) / cathode buffer layer (LiF) / metal electrode (Al) were laminated in this order.

[Measurement of Luminous Efficiency of Organic EL Elements Obtained in Example 2, Reference Example 3 and Comparative Examples 6-7]
When measuring the luminous efficiencies of the organic EL devices obtained in Example 2, Reference Example 3 and Comparative Examples 6 to 7, the organic EL devices obtained in Reference Example 1 and Comparative Examples 1 to 3 were measured. The current efficiency (CE) and the power efficiency (PE) of the organic EL elements obtained in Example 2, Reference Example 3 and Comparative Examples 6 to 7 were determined in the same manner as in the above. Table 8 shows the obtained results. Moreover, the current efficiency (CE) and power of the organic EL element obtained in Example 2 with respect to the current efficiency (CE) and power efficiency (PE) of the organic EL element obtained in Reference Example 3 and Comparative Examples 6-7. Table 10 also shows the results of calculating the ratio (magnification) at which the efficiency (PE) was improved.

  As is clear from the results shown in Table 10, when the organic EL elements obtained in Example 2 and Reference Example 3 are compared with the organic EL elements obtained in Comparative Example 7, the above condition (A) is satisfied. In the organic EL element using the diffraction grating (Example 2, Reference Example 3), the light emission efficiency is sufficiently improved as compared with the organic EL element not using the diffraction grating (Comparative Example 7). confirmed. Moreover, the organic EL element obtained in Example 2 that satisfies the conditions (A) to (C) is compared with the organic EL element obtained in Comparative Example 6 that uses only a hemispherical lens without using a diffraction grating. Thus, it was confirmed that higher luminous efficiency can be achieved by satisfying the conditions (A) to (C). In addition, also from the comparison with the organic EL element obtained by the reference example 3 and the comparative example 7, it is clear that higher luminous efficiency can be achieved by satisfy | filling conditions (A)-(C). Furthermore, in consideration of the difference between the organic EL elements obtained in Example 2 and Reference Example 3 only in the presence or absence of a hemispherical lens, the above conditions (A) to (C) are satisfied and the light of the glass substrate is satisfied. It has been found that by providing a hemispherical lens on the extraction surface side, the rate of improvement in current efficiency (CE) and power efficiency (PE) becomes higher. As described above, from the results shown in Table 10, the luminous efficiency of the organic EL element is obtained by satisfying the above-mentioned conditions (A) to (C) and providing an optical member such as a hemispherical lens on the light extraction surface side of the glass substrate. It was confirmed that it improved at a higher level.

  From the above results, it was confirmed that a sufficient diffraction effect can be obtained by using a diffraction grating satisfying the condition (A). Moreover, in the organic EL elements obtained in Reference Examples 1 to 3 and Examples 1 and 2 in which the glass transition temperature of the organic material forming each layer of the organic layer other than the phosphorescent material is 70 ° C. or higher, the organic layer Each of the irregularities formed on the surface of the surface facing the metal electrode in each layer has a standard deviation (σ) of the irregularity depth in the range of 15 to 50 nm, and the standard deviation of the first irregularity It was found that the change rate of the standard deviation of the unevenness depth is in the range of + 15% to −15%, and the film thickness of each layer is very uniform (in Reference Example 1, Although the hole blocking layer (thickness: 5 nm) is not particularly evaluated for the irregular shape characteristics, the hole blocking layer in Reference Example 1 is sufficiently thin and laminated on the hole blocking layer. The standard deviation of the unevenness of the electron transport layer and the standard deviation The unevenness formed on the surface of the surface of the hole blocking layer facing the metal electrode also has a standard deviation (σ) of the unevenness depth in the range of 15 to 50 nm. In addition, it is clear that the change rate of the standard deviation of the concavo-convex depth with respect to the standard deviation of the first concavo-convex is in the range of + 15% to -15%, and it is understood that this condition is satisfied. And since the electrode buffer layer and metal electrode which consist of metal materials are formed by the vapor deposition method on such an organic layer with high followable | trackability with respect to such 1st unevenness | corrugation, Reference Examples 1-3 and Examples 1-2. In the organic EL device obtained in the above, the unevenness (second unevenness) formed on the surface of the surface facing the organic layer of the metal electrode has a standard deviation (σ) of the unevenness depth in the range of 15 to 50 nm. In addition, it was found that the change rate of the standard deviation of the unevenness depth with respect to the standard deviation of the first unevenness is in the range of + 15% to −15%. In addition, from the above results, in the organic EL element of the present invention satisfying the above conditions (A) to (C), including an optical member for extracting light to the outside on the light extraction surface side of the glass substrate, It was confirmed that a more advanced light extraction effect can be stably obtained by the optical member and the diffraction grating.

(Reference Example 4)
First, 2.5 g of tetraethoxysilane (TEOS) and 2.1 g of methyltriethoxysilane (MTES) were added dropwise to a mixture of 24.3 g of ethanol, 2.16 g of water and 0.0094 g of concentrated hydrochloric acid. A sol solution was obtained by stirring for 2 hours at a temperature of 45 ° C. and a humidity of 45%. Next, a sol solution was applied onto a 0.7 mm thick glass substrate (made of soda lime) with a bar coater to produce a coating film of the sol solution on the glass substrate. And 60 seconds after the production of the coating film, the coating film on the glass substrate was manufactured in Example 1 using a heated pressing roll by adopting the method as described below. The second mold (M-2) was pressed to form a diffraction grating (uneven layer) on the glass substrate.

  That is, first, as the pressing roll, a roll provided with a heater inside and coated with heat-resistant silicone having an outer periphery of 4 mm thick, having a roll diameter (diameter) of 50 mm and an axial length of 350 mm was used. . Then, the surface on which the concave / convex pattern of the second mold (M-2) is formed is pressed against the coating film on the glass substrate while rotating a pressing roll heated to 80 ° C. from one end of the glass substrate toward the other end. It was. In this way, after the pressing of the second mold (M-2) was finished, the second mold (M-2) was peeled off by hand so that the peeling angle was about 30 ° from the one end to the other end. . Then, after peeling off the second mold, the glass substrate with a cured coating film on which the unevenness derived from the unevenness of the second mold is formed is heated at 300 ° C. for 60 minutes using an oven, and is formed of an inorganic layer. A glass substrate on which a lattice (uneven layer) was laminated was obtained. The inorganic layer had a thickness of 0.3 μm.

The Fourier transform image of the diffraction grating (inorganic layer) obtained in this way shows a circular pattern having an approximate center at the origin where the absolute value of the wave number is 0 μm ⁻¹ , as in Example 1. In addition, the circular pattern has 90% or more of bright spots in all the bright spots constituting the Fourier transform image in the region where the absolute value of the wave number is in the range of 10 μm ⁻¹ or less. Was confirmed.

  In addition, since the diffraction grating obtained in Example 4 used the same mold as in Example 1, the average value of the uneven depth distribution (m) and the standard deviation of the uneven depth distribution (σ) The average height of the unevenness of the diffraction grating, the average pitch of the unevenness, the median value (M) of the unevenness depth distribution, the kurtosis (k) of the unevenness, and the like have the same characteristics as in Example 1. It was.

Next, on the surface of the diffraction grating on the glass substrate formed as described above, a transparent electrode [ITO, thickness: 120 nm], a hole transport layer [TCTA (Tg: 149 ° C.), thickness: 35 nm], First light emitting layer [TCTA (Tg: 149 ° C.) containing 7.0% by mass of Ir (ppy) ₃ , thickness: 15 nm], second light emitting layer [TPBi (1,3,5-tris (N− Phenylbenzimidazolyl) benzene, Tg: 124 ° C.) containing 7.0% by mass of Ir (ppy) ₃ , thickness: 15 nm], electron transport layer [TPBi (Tg: 124 ° C.), thickness: 50 nm], metal Cathode buffer layer [lithium fluoride (LiF), thickness: 1.5 nm] and metal electrode [aluminum, thickness: 50 nm] made of a base material are maintained in the shape of the first unevenness formed on the surface of the diffraction grating The In this way, the glass substrate / diffraction grating / transparent electrode / hole transport layer / first light emitting layer / second light emitting layer / electron transport layer / cathode buffer layer made of metal material / metal electrode A laminated body for an organic EL device that was sequentially laminated (in the device, the organic layer was a laminated structure of a hole transport layer / first light emitting layer / second light emitting layer / electron transport layer) was obtained. In addition, the lamination process of each layer is as follows. That is, first, the transparent electrode was laminated by a sputtering method. The transparent electrode was exposed to oxygen plasma after film formation to increase the work function (radical treatment). Moreover, the hole transport layer was laminated | stacked by the vacuum evaporation method. Furthermore, the first light emitting layer was laminated by a co-evaporation method using TCTA and Ir (ppy) ₃ while adjusting the amount of Ir (ppy) ₃ introduced in the layer to 7% by mass. . The second light emitting layer was laminated by co-evaporation using TPBi and Ir (ppy) ₃ while adjusting the amount of Ir (ppy) ₃ introduced into the layer to be 7% by mass. . Moreover, the electron carrying layer, the cathode buffer layer (lithium fluoride layer), and the metal electrode were each laminated | stacked by the vacuum evaporation method. After metal electrode formation, changes in the standard deviation of the concavo-convex depth with respect to the standard deviation (σ) of the concavo-convex depth of the surface facing the diffraction grating of the metal electrode and the standard deviation of the first concavo-convex formed on the surface of the diffraction grating The rate was also determined. The obtained values are shown in Table 11.

  As is apparent from the results shown in Table 11, in the organic EL element obtained in Reference Example 4, the unevenness formed on the surface of the metal electrode facing the diffraction grating is the standard deviation (σ) of the unevenness depth. Is within the range of 15 to 50 nm, and the rate of change of the standard deviation of the unevenness depth of the surface facing the diffraction grating of the metal electrode with respect to the standard deviation of the first unevenness is within the range of + 15% to −15% It was confirmed that the thickness of each layer was very uniform. From these results, it was found that the organic EL element obtained in Reference Example 4 satisfies the above-described conditions (A) to (C).

  Further, the luminous efficiencies of the organic EL elements obtained in Reference Example 4 and Comparative Example 5 were measured in the same manner as the method employed in the measurement of the luminous efficiency of the organic EL elements described above. Reference Example 4 and Comparative Example The current efficiency (CE) and power efficiency (PE) of the organic EL device obtained in 5 were determined. The results obtained are shown in Table 12.

  As is clear from the results shown in Table 12, when the organic EL device obtained in Reference Example 3 and the organic EL device obtained in Comparative Example 5 are compared, the above conditions (A) to (C) are satisfied. As a result, it was confirmed that the luminous efficiency was sufficiently improved. Further, as is clear from the results shown in Table 12, in the organic EL device obtained in Reference Example 3, it was found that the rate of improvement in current efficiency (CE) and power efficiency (PE) was sufficiently high. . As is clear from the results of the above-described examples and comparative examples (results shown in Table 8 and Table 10), the light of the transparent support substrate of the element that satisfies all the above conditions (A) to (C) It has been confirmed that an organic EL element having an optical member such as a hemispherical lens on the extraction surface side (organic EL element of the present invention) can achieve very high light extraction efficiency. Therefore, also in the organic EL element obtained in Reference Example 4 that satisfies the above-described conditions (A) to (C), by further disposing an optical member such as a hemispherical lens on the light extraction surface side of the glass substrate, It can be seen that a high luminous efficiency can be achieved.

  As described above, according to the present invention, there is provided an organic EL element that can improve the light extraction efficiency of the organic EL element at a higher level and can achieve a sufficiently high luminous efficiency. It becomes possible to do.

  Therefore, the organic EL element of the present invention is particularly useful as an organic EL element for use in a lighting device or the like.

  DESCRIPTION OF SYMBOLS 10 ... Transparent support substrate, 11 ... Diffraction grating, 11 '... Diffraction grating forming material, 12 ... Transparent electrode, 13 ... Organic layer, 13A and B ... Arbitrary layer in an organic layer, 131 ... Hole transport layer, 132 ... Light emitting layer, 132 (a) ... first light emitting layer, 132 (b) ... second light emitting layer, 133 ... electron transport layer, 134 ... hole blocking layer, 14 ... metal electrode, 15 ... optical member, 16 ... cathode buffer Layer (electron injection layer), 20 ... base material, 21 ... uneven layer made of first polymer segment, 22 ... seed layer, 23 ... metal layer (electroplating layer), 30 ... master member for transfer, 31 ... diffraction grating Forming mold (mold), P1-2: lowest point of recess, P3-4: apex of projection, X: thickness between recesses, Y: thickness between projections.

Claims (8)

Transparent support substrate,
A diffraction grating composed of a concavo-convex layer disposed on one surface side of the transparent support substrate and having a first concavo-convex formed on the surface thereof,
A transparent electrode, an organic layer having at least a light emitting layer, a metal electrode, and a metal electrode, which are sequentially stacked on the diffraction grating so that the shape of the first unevenness formed on the surface of the diffraction grating is maintained. ,
An optical member disposed on the other surface side of the transparent support substrate;
An organic EL device comprising:
The following conditions (A) to (C):
[Condition (A)] When the unevenness analysis image obtained by analyzing the shape of the first unevenness using an atomic force microscope is subjected to a two-dimensional fast Fourier transform process to obtain a Fourier transform image, the Fourier transform image is obtained. The converted image shows a circular or annular pattern whose center is the origin where the absolute value of the wave number is 0 μm ⁻¹ , and the absolute value of the wave number is 10 μm ⁻ Be in an area that is within ¹ or less,
[Condition (B)] Each of the first unevenness and the second unevenness formed on the surface of the surface facing the organic layer of the metal electrode is analyzed using an atomic force microscope. The standard deviation of the depth distribution of the unevenness obtained based on the unevenness analysis image obtained as described above is 15 to 50 nm,
[Condition (C)] The rate of change of the standard deviation of the depth distribution of the second unevenness with respect to the standard deviation of the depth distribution of the first unevenness is + 15% to −15%.
That it meets,
The unevenness formed on the surface of the transparent electrode and the surface of the organic layer facing the metal electrode of each layer having a thickness of 10 nm or more has a standard deviation of the unevenness depth distribution of 15 to 50 nm. And the rate of change of the standard deviation of the unevenness depth distribution with respect to the standard deviation of the depth distribution of the first unevenness is + 15% to −15%,
The material constituting the organic layer is an organic material having a glass transition temperature of 70 ° C. to 300 ° C.,
The organic layer further comprises a hole transport layer and an electron transport layer, and the light emitting layer is a layer containing a phosphorescent material and a host material; and
The light emitting layer has a two-layer structure of a first light emitting layer and a second light emitting layer, and the types of host materials of the first light emitting layer and the second light emitting layer are different from each other;
An organic EL element characterized by the above. The unevenness formed on the surface of the transparent electrode and the surface of each layer of the organic layer facing the metal electrode is such that the standard deviation of the unevenness depth distribution is 15 to 50 nm, and 2. The organic EL device according to claim 1, wherein the change rate of the standard deviation of the unevenness depth distribution with respect to the standard deviation of the first unevenness depth distribution is + 15% to −15%. . The material constituting the hole transport layer and the host material of the first light emitting layer are made of the same material, and the material constituting the electron transport layer and the host material of the second light emitting layer are made of the same material The organic EL element according to claim 1, wherein: 4. The organic EL element according to claim 1 , wherein the host material in the light emitting layer is an organic material having a glass transition temperature of 100 ° C. to 300 ° C. 5. 5. The organic EL element according to claim 1 , wherein an average height of the first unevenness is in a range of 20 to 200 nm. 6. The organic EL element according to claim 1 , wherein an average pitch of the first unevenness is in a range of 100 to 700 nm. The organic EL element according to claim 1 , wherein the concavo-convex layer of the diffraction grating is an inorganic layer. The organic EL element according to claim 1 , wherein the optical member is a lens member.