JP2011086385A - Light-emitting device and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the purity of color relating to an organic EL device. <P>SOLUTION: An organic EL device 1 includes: a light-emitting element 2 which contains a first electrode layer 18, a second electrode layer 22, and a light-emitting function layer 20 arranged between them; a reflecting layer 12 which reflects the light emitted from the light-emitting function layer; and a semi-transparent semi-reflection layer 22 which is arranged on the side opposite to the reflecting layer across the light-emitting function layer to reflect a portion of the light emitted from the light-emitting function layer toward the light-emitting function layer and transmit the other portion (the second electrode layer and the semi-transparent semi-reflection layer are shared in the figure). In addition, a reflection enhancing layer 23 is so arranged as to come into contact with the semi-transparent semi-reflection layer on the side opposite to the reflection layer with the semi-transparent semi-reflection layer as a center. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a light emitting device and an electronic apparatus including an organic EL (electro luminescent) element and the like.

An organic light emitting diode (OLED), that is, an organic EL (electro luminescent) element, has attracted attention as a thin and light-emitting source, and an image display device including a large number of organic EL elements has been developed. The organic EL element has a structure in which at least one organic thin film formed of an organic material is sandwiched between a pixel electrode and a counter electrode.
In the field of organic EL elements, a technique is known that uses amplifying interference, ie, resonance, to enhance light of a specific wavelength among emitted light. With this technology, the color purity of the emitted color can be increased, and the efficiency of the emitted light with respect to the emitted light can be increased.
As such an image display device, for example, those disclosed in Patent Documents 1 and 2 are known.

Japanese Patent No. 2797883 JP 2008-218081 A

However, the techniques of Patent Documents 1 and 2 have the following problems.
That is, according to the technique of Patent Document 1, it is possible to intensify light of a specific wavelength by the action of the “micro optical resonator” ([0015] [0018], etc. of Patent Document 1). With regard to means for further strengthening, that is, means for more effectively utilizing the resonance action of the optical resonator, mention will be made in particular except for a contrivance relating to the reflectance of the translucent reflective layer ([0016] of Patent Document 1). There is no place.
Further, in the technique of Patent Document 2, as in Patent Document 1, it is considered that the effect of enhancing the light of a specific wavelength by the action of the optical resonator can be enjoyed ([0028] of Patent Document 2). However, in this technique, it is assumed that a transparent electrode is formed in contact with the organic compound layer, and according to this, there is a high risk of causing some damage to the organic compound layer when forming the transparent electrode in the manufacturing process. (See also [Claim 1] or [FIG. 1] of Patent Document 2). Further, it is considered that the amount of light reflection at the interface between the transparent cathode electrode 14 and the optical path length adjusting layer 15 described in Patent Document 2 is limited, and as in Patent Document 1, the resonance action by the optical resonator is more effective. It cannot be said that it can be used.

  An object of the present invention is to provide a light-emitting device and an electronic device that can solve at least a part of the problems described above.

  In order to solve the above-described problems, a light emitting device of the present invention includes a first electrode layer, a second electrode layer, and a light emitting functional layer disposed between the first and second electrode layers, and A reflection layer that reflects light emitted from the light emitting functional layer toward the light emitting functional layer; and a light that is disposed on the opposite side of the reflective layer across the light emitting functional layer and that is emitted from the light emitting functional layer A semi-transparent semi-reflective layer that reflects a part of the light-emitting functional layer toward the light-emitting functional layer and transmits the other part, and on the opposite side of the reflective layer located around the semi-transparent semi-reflective layer, And the reflection enhancing layer disposed so as to be in contact with the translucent semi-reflective layer, wherein the light emitting element includes one that emits red light, one that emits green light, and one that emits blue light. The layer includes a light emitting element emitting red light, a light emitting element emitting green light, and a blue light emitting element. The thickness corresponding to each of the common layer formed with a uniform thickness regardless of the light emitting element to emit, the light emitting element emitting red light, the light emitting element emitting green light, and the light emitting element emitting blue light And individual conditioning layers made from different materials and different from the common layer.

According to the present invention, since the reflection enhancing layer is in contact with the translucent semi-reflective layer, relatively strong light reflection can occur at the interface between these two layers. Therefore, in the configuration according to the present invention, of the light generated in the light emitting functional layer, the absolute amount of light that returns to the optical resonator constituted by the translucent semi-reflective layer and the reflective layer is relatively large. Therefore, the action of the optical resonator can be further strengthened, in other words, the resonance action by the optical resonator can be used more effectively.
In addition, in the present invention, the thickness of the reflection enhancement layer having such a function differs with respect to the light emitting elements corresponding to red, green, and blue according to the difference in the thickness of the individual adjustment layers. This difference makes it possible to optimize the thickness to the wavelength of each color light, so that the above-described effect becomes more effective in the present invention.

In the light emitting device of the present invention, the light emitting element, the reflective layer, the semitransparent semireflective layer, and the reflection enhancement layer are constructed so as to form a laminated structure on a substrate, and the first electrode layer includes the first electrode layer. The semi-transparent semi-reflective layer includes the second electrode layer and functions as a cathode, and the common layer is in contact with the semi-transparent semi-reflective layer. By this, you may comprise so that the said semi-transparent semi-reflective layer may be touched.
According to this aspect, the translucent transflective layer includes all or part of the second electrode layer, that is, the translucent transflective layer and all or part of the second electrode layer can be shared. Since it is used as well, the efficiency and simplification of the device structure can be achieved, and the ease of manufacturing can be improved.
Further, in this aspect, if a manufacturing method in which the respective layers are sequentially stacked on the substrate is employed, there is no need to manufacture a transparent electrode in contact with the light emitting functional layer as in the conventional technique. There is almost no risk of any damage to the light emitting functional layer. In addition, in this embodiment, the translucent transflective layer and the common layer are in contact with each other, that is, after the translucent transflective layer is formed, a film having a thickness corresponding to each color light emitting element is not formed. Since the common layer having a certain thickness is formed prior to the individual adjustment layer, the possibility of some damage to the light emitting functional layer is further reduced (the common layer is a light emitting functional layer or a half layer). For the transparent semi-reflective layer, it functions as a protective layer.)

In this aspect, the refractive index of the common layer and the refractive index of the individual adjustment layer included in the reflection enhancement layer may be higher than the refractive index of the translucent semi-reflective layer.
According to this aspect, light is more easily reflected at the interface between the translucent semi-reflective layer and the reflection enhancement layer, so that the effect of the present invention described above becomes more effective.

Alternatively, in the above-described aspect in which the semitransparent semireflective layer is shared with the second electrode layer, the light emitting element, the reflective layer, the semitransparent semireflective layer, and the reflection enhancement layer are filled with an inert gas. The reflection enhancement layer is in contact with the inert gas, and the refractive index of the common layer and the refractive index of the individual adjustment layer included in the reflection enhancement layer are: You may comprise so that it may be higher than the refractive index of the said inert gas.
According to this aspect, light reflection is more likely to occur not only at the interface between the translucent semi-reflective layer and the reflection enhancement layer, but also at the interface between the reflection enhancement layer and the inert gas. Such an effect becomes more effective.

Further, in the above-described aspect in which the refractive index of the common layer or the like is higher than the refractive index of the translucent semi-reflective layer, the refractive index of the common layer and the refractive index of the individual adjustment layer included in the reflection enhancement layer The difference between the refractive index of the translucent and semi-reflective layer may be greater than the difference between the refractive index of the common layer and the refractive index of the individual adjustment layer.
According to this aspect, since the difference in refractive index between the common layer and the individual adjustment layers is suppressed to a certain degree, it is difficult for unnecessary light to be reflected at the interface between the two layers. The effect according to is further effective.

In the light emitting device of the present invention, the optical distance from the reflective layer to the interface facing the reflective layer in the semi-transparent semi-reflective layer is determined based on d calculated by Formula (i). You may comprise as follows.
d = ((2πm + φ _D + φ _U ) / 4π) · λ (i)
Here, lambda is the wavelength which is set as a resonant object is phi _D, the light of wavelength lambda to progress to the reflective layer from the light-emitting functional layer side, a phase change when reflected by the reflective layer, φ _U is a phase change when light of wavelength λ traveling from the light emitting functional layer side to the semi-transparent semi-reflective layer is reflected by the semi-transparent semi-reflective layer, and m is a positive integer.
According to this aspect, in the resonator structure including the light emitting element, the reflective layer, and the semi-transparent semi-reflective layer, the resonance phenomenon can be suitably generated.
Note that the “wavelength set as the resonance target” (hereinafter, also referred to as “resonance target wavelength”) in this aspect corresponds to the light emitting elements corresponding to each of red, green, and blue according to the present invention. Thus, the wavelengths of these three colors can be substituted. That is, if the wavelengths of these three colors are λr, λg, and λb, λ can take any of these λr, λg, or λb, so that d is, for example, dr, dg, db (Thus, in this case, the value of “d” may be different for each light emitting element).
Further, in this aspect, in order to realize the three-color display as described above, “the translucent semi-reflective layer is disposed on the opposite side of the light-emitting functional layer with the semi-transparent semi-reflective layer interposed therebetween. It is preferable to further include a “color filter that transmits the transmitted light”. In this case, the resonance target wavelength λ can be set to “a wavelength corresponding to the peak of transmittance of the color filter” or the like. is there.

Moreover, in order to solve the said subject, the electronic device of this invention is equipped with the various light-emitting devices mentioned above.
Since the electronic device of the present invention includes the above-described various light emitting devices, the electronic device can better enjoy the function of the optical resonator, in other words, the electronic that can more effectively enjoy the effect of improving the color purity. Equipment is provided.

It is sectional drawing which shows the outline of the light-emitting device which concerns on embodiment of this invention. It is an expanded sectional view in the circle A of FIG. It is a schematic diagram which shows simply the locus | trajectory of the light in the resonator structure in the light-emitting device of FIG. It is a figure showing the luminous efficiency improvement effect by the light-emitting device of FIG. 1 with a specific numerical value. It is a figure which shows the experimental result of the spectrum of the light emitted from the light-emitting device of FIG. FIG. 5 is a diagram for explaining the operation of a reflection enhancement layer 23. It is a comparative example (absence of the reflection enhancement layer 23) of FIG. It is a graph showing the wavelength dependence of the refractive index of SiON and Alq3. It is a graph showing the difference between both refractive indexes shown in FIG. It is a perspective view which shows the electronic device to which the light-emitting device based on this invention is applied. It is a perspective view which shows the other electronic device to which the light-emitting device based on this invention is applied. It is a perspective view which shows the further another electronic device to which the light-emitting device based on this invention is applied.

  Hereinafter, an embodiment according to the present invention will be described with reference to FIGS. 1 and 2. In addition to FIGS. 1 to 3 referred to here, in each drawing referred to below, the ratio of dimensions of each part may be appropriately different from the actual one.

<Configuration of organic EL device, particularly its cross-sectional structure>
FIG. 1 is a cross-sectional view schematically showing an organic EL device (light-emitting device) 1 according to an embodiment of the present invention, and FIG. 2 is an enlarged cross-sectional view in a circle indicated by a symbol A shown in FIG. (In particular, details of each pixel are shown).
As shown in FIG. 1, the entire organic EL device 1 is sealed in a space surrounded by a wall surface C made of an appropriate material such as glass (or resin material, metal). An inert gas G is enclosed in the space. Specific examples of the inert gas G include N ₂ gas, argon gas, and the like.

The organic EL device 1 includes a light emitting panel 3 as shown in FIG.
The light emitting panel 3 has a plurality of light emitting elements (pixels) 2 (2R, 2G, 2B) as shown in the figure. The organic EL device 1 of this embodiment is used as a full-color image display device. The light emitting element 2R is a light emitting element whose emitted light color is red, and the light emitting elements 2G and 2B are light emitting elements whose emitted light colors are green and blue, respectively.
Each light emitting element 2 is connected to a power supply TFT (thin film transistor), wiring, and the like. The TFT, wiring, and the like are constructed on the substrate 10 between, for example, appropriate interlayer insulating films.
In FIG. 2, the TFTs and wirings are not shown in order to prioritize the visibility of the drawing. Incidentally, the interlayer insulating film includes, for example, a reflective layer 12 and a first electrode layer 18 described later. It can be formed in various places such as between the reflective layer 12 and the substrate 10, but this is also not shown). Further, in FIG. 2, only three light emitting elements 2 are shown, but actually, a larger number of light emitting elements than those shown are provided. Hereinafter, the subscripts R, G, and B of the constituent elements correspond to the light emitting elements 2R, 2G, and 2B.

  The illustrated light emitting panel 3 is a top emission type. The light emitting panel 3 includes a substrate 10. The substrate 10 may be formed of a transparent material such as glass, or may be formed of an opaque material such as ceramic or metal.

A reflective layer 12 having a uniform thickness is formed at least on the substrate 10 so as to overlap the light emitting element 2. The reflective layer 12 is formed of a material having high reflectivity such as Al (aluminum), Cr (chromium), Ag (silver), or an alloy containing these, and the light (light emission) traveling from the light emitting element 2 is formed. (Including light emission from the element 2) is reflected upward in FIG.
In addition to the above-described Al, Cr, and Ag, for example, Cu, Zn, Nd, Pd, and the like may be added to the reflective layer 12. Thereby, improvement in heat resistance and the like are expected.
The thickness of the reflective layer 12 is preferably about 50 to 150 [nm].

  On the substrate 10, partition walls (separators) 16 for separating the light emitting elements 2 are formed. The partition wall 16 is formed of an insulating resin material such as acrylic, epoxy, or polyimide.

Each light emitting element 2 includes a first electrode layer 18, a second electrode layer 22, and a light emitting functional layer 20 disposed between the first electrode layer 18 and the second electrode layer 22.
In the present embodiment, the first electrode layer 18 is a pixel electrode provided in each pixel (light emitting element 2), for example, an anode. The first electrode layer 18 is formed of a transparent material such as ITO (indium tin oxide) or ZnO ₂ .

In the present embodiment, the light emitting functional layer 20 (20R, 20G, 20B) is formed to correspond to each of the light emitting elements 2R, 2G, 2B. The light emitting functional layers 20R, 20G, and 20B have different thicknesses depending on the light emission color, and the optical distance between the reflective layer 12 and the second electrode layer 22 in each of the light emitting elements 2R, 2G, and 2B. d (d _R , d _G , d _B ) is different. This is for amplifying light of a specific wavelength in each light emitting element 2. That is, light of red wavelength is amplified in the light emitting element 2R, light of green wavelength is amplified in the light emitting element 2G, and light of blue wavelength is amplified and emitted in the light emitting element 2B. In the figure, d (d _R , d _G , d _B ) indicates an optical distance, and does not indicate an actual distance. This point will be described in more detail in the section <Light reflection and transmission model> below.

The light emitting functional layer 20 has at least an organic light emitting layer. In order to emit light of each color as described above, the organic EL material included in the organic light emitting layer may be appropriately changed. When a current flows through such an organic light emitting layer, light having red, green and blue light components is emitted. The organic light emitting layer may be a single layer or may be composed of a plurality of layers (for example, a blue light emitting layer that emits mainly blue light when current flows and a yellow light emitting layer that emits light including red and green when current flows). It may be.
In addition to the organic light emitting layer, the light emitting functional layer 20 may have layers such as a hole transport layer, a hole injection layer, an electron block layer, a hole block layer, an electron transport layer, and an electron injection layer. Among these, the hole injection layer is, for example, HI-406 (made by Idemitsu Kosan Co., Ltd.) or CuPc (copper phthalocyanine), and the hole transport layer is α-NPD (N, N′-di (1-naphthyl) -N, N′-diphenyl-1,1′-biphenyl-4,4′-diamine) and the like, and the electron transport layer can be made of aluminum quinolinol complex (Alq3) and the like, and the electron injection layer can be made of LiF and the like.

The second electrode layer (semi-transparent semi-reflective layer) 22 is formed of an alloy or a metal material such as MgAl, MgCu, MgAu, and MgAg. In the present embodiment, the second electrode layer 22 is a common electrode provided in common to a plurality of pixels (light emitting elements), for example, a cathode.
The second electrode layer 22 has a uniform thickness regardless of the emission color of the light emitting element 2. More specifically, for example, the second electrode layer 22 is preferably about 5 to 20 nm thick. Since the thickness is relatively small, the second electrode layer 22 is translucent and semi-reflective.
The second electrode layer 22 transmits a part of the light (including the light from the light emitting functional layer 20) traveling from the light emitting functional layer 20 to the upper side of the figure, and transmits the other part of these lights. Reflected downward in the figure, that is, toward the first electrode layer 18.

  Inside the opening (pixel opening) formed between the plurality of partition walls 16, the light emitting functional layer 20 is in contact with the first electrode layer 18. In the light emitting element 2, the first electrode layer 18 and the second electrode When a current flows between the layer 22, holes are supplied from the first electrode layer 18 and electrons are supplied from the second electrode layer 22 to the light emitting functional layer 20 in the light emitting element 2. These holes and electrons recombine to generate excitons, and when the excitons transition to the ground state, energy emission, that is, a light emission phenomenon occurs. Accordingly, the light emitting region of the light emitting element 2 is roughly defined by the pixel openings formed between the partition walls 16. That is, the pixel opening of the partition wall 16 separates the light emitting element 2.

A reflection enhancement layer 23 is formed above the second electrode layer 22 in FIG. The reflection enhancement layer 23 includes a sealing layer 24 and an individual adjustment layer 25.
As illustrated, the sealing layer (common layer) 24 is formed in common with respect to each of the light emitting elements 2R, 2G, and 2B, and has a uniform thickness. The thickness is preferably about 50 to 150 [nm]. The sealing layer 24 is made of, for example, SiON, SiN or the like. The sealing layer 24 made of such a material has a sealing function for preventing moisture and oxygen from entering the light emitting functional layer 20. Thereby, the deterioration rate of the light emission functional layer 20 is relieved, and the lifetime improvement is achieved.
On the other hand, as shown in the drawing, the individual adjustment layer 25 is individually formed for each of the light emitting elements 2R, 2G, 2B, and the thickness thereof corresponds to each of the light emitting functional layers 20R, 20G, 20B. Different. Specifically, T _R > T _G > T _B is between the thicknesses T _R , T _G , and T _B of the individual adjustment layers 25 corresponding to each of the light emitting elements 2R that emit red, green, and blue light. To establish. The thickness _T R of the individual adjustment layer 25, _{T G} or _{T B} is specifically, for example, is suitable is a 0 to 200 [nm] degree.

Further, the refractive index of the sealing layer 24 and the individual adjustment layer 25 is relatively higher than the refractive index of the second electrode layer 22. On the other hand, as described with reference to FIG. 1, the organic EL device 1 of the present embodiment is sealed with the inert gas G. The inert gas G is individually separated as shown in FIG. It is in direct contact with the adjustment layer 25. The refractive index of the inert gas G is smaller than the refractive index of the individual adjustment layer 25. As a result, in the present embodiment, in the present embodiment, from the second electrode layer 22 toward the upper side in FIG. 2, the layer having a low refractive index is changed to a higher layer (from the second electrode layer 22 to the sealing layer 24 or individually adjusted). There is a change from the high layer to the low layer (from the sealing layer 24 or the individual adjustment layer 25 to the inert gas G).
Such an individual adjustment layer 25 can be made of, for example, Alq3. Alq3 has a refractive index of 1.6 or more at a wavelength of 555 [nm]. Further, SiON that can form the sealing layer 24 also has a refractive index of 1.6 or more at a wavelength of 555 [nm] (see FIG. 8 described later).
As described above, the sealing layer 24 and the individual adjustment layer 25 in this embodiment are formed as different layers using different materials, but the difference between them is small in terms of refractive index. This point will be described later with reference to FIGS.

<Light reflection and transmission model>
FIG. 3 is a schematic diagram schematically showing the locus of light emitted from the light emitting functional layer 20. A part of the light emitted from the light emitting functional layer 20 travels toward the first electrode layer 18 side on the surface of the reflective layer 12 on the light emitting functional layer 20 side, as shown on the left side of the drawing. reflect. A phase change when the reflected and phi _D. On the other hand, the other part of the light travels toward the second electrode layer 22 as shown on the right side in the figure, and the surface of the second electrode layer 22 on the light emitting functional layer 20 side (second The light is reflected at the interface of the electrode layer 22 facing the reflective layer 12. A phase change when the reflected and phi _U.
Of these cases, in the latter case, that is, when the light is reflected by the second electrode layer 22, as shown in FIG. 3, the light passes through the light emitting functional layer 20 and the first electrode layer 18 after the reflection. Then, the light is reflected again by the surface of the reflective layer 12 on the light emitting functional layer 20 side. Hereinafter, the reflection of light is repeated infinitely in the second electrode layer 22 and the reflection layer 12 in principle. The same applies to the former case, that is, the case where light is reflected by the reflective layer 12, although not shown.
In FIG. 3, the illustration of the optical path change due to light refraction at each interface is omitted, and the optical path is shown by a simple straight line or curve.

In the present embodiment, on the assumption that such a reflection phenomenon occurs, the optical distance d shown in FIG. 3 (or FIG. 2) is determined by the following equation (1).
d = ((2πm + φ _D + φ _U ) / 4π) · λ (1)
Here, λ is a wavelength [nm] set as a resonance target, and m is an arbitrary integer. Note that the significance of phi _D and phi _U are as described above.

In the present embodiment, λ or d is determined according to the light emitting elements 2R, 2G, and 2B as is apparent from FIG. More specifically, for example, λ _R = 610 [nm], λ _G = 550 [nm], and λ _B = 470 [nm] can be substituted for the wavelengths λ related to the light emitting elements 2R, 2G, and 2B. . The optical distance d is obtained as d _R , d _G and d _B (see FIG. 1) corresponding to these λ _R , λ _G and λ _B, respectively. In the root finding of d _R , d _G and d _B , φ _D and φ _{U in} equation (1) are values corresponding to λ _R , λ _G and λ _B (φ _D = φ _DR , Φ _DG , φ _DB , or φ _U = φ _UR , φ _UG , φ _UB ).

Then, in order to realize on an actual device _d R, _{d G} and _{d B} obtained by the above formula (1), in the present embodiment, as shown in FIG. 1, the light-emitting functional layer 20R, the 20G and 20B The thickness (particularly, the thickness of a hole transport layer or the like (not shown) as a part thereof) is adjusted for each light emitting element 2 (2R, 2G, and 2B).
In general, the “optical distance” for a certain substance is expressed as the product of the physical thickness of the substance and its refractive index. Therefore, it is assumed that the thickness of the light emitting functional layer 20 is only adjusted by adjusting the thickness of the hole transport layer. If the physical thickness of the hole transport layer is t and the refractive index is n _HTL , then the hole transport layer, the other light emitting functional layer 20, and the first The optical distance D of the entire one electrode layer 18 is
D = t · n _HTL + D ₂₀ + D ₁₈ (2)
It becomes. However, D ₂₀ is the optical distance, D ₁₈ of the light-emitting functional layer 20 other than the hole transport layer is an optical distance of the first electrode layer 18.
In this equation (2), n _HTL cannot basically be moved. Therefore, in order to establish one of D = d _R , D = d _G and D = d _B , it is necessary to vary t. In this manner, will be found _{t B,} but each time _{t G} and D = _{d B} when the _t R, D = _{d G} at the time of D = _{d R,} based on these, a hole transport The thickness of the layer, that is, the thickness of the light emitting functional layer 20 is adjusted. In the root finding of t _R , t _G and t _B , n _HTL in the formula (2) is a value corresponding to each of λ _R , λ _G and λ _B (n ₁₈ = n _{HTL R} , n _{HTL G} , n _{HTL B} ) is used.
As described above, in the present embodiment, the optical distance associated with the optical resonator is adjusted through the adjustment of the thickness of the light emitting functional layer 20, but the present invention is not limited to such a form. is not. For example, instead of or in addition to the adjustment of the thickness of the hole transport layer described above, the optical distance of the optical resonator may be adjusted through the adjustment of the thickness of the electron transport layer, or In place of or in addition to the adjustment of the thickness of the light emitting functional layer 20 (any one of the layers), the optical distance of the optical resonator is adjusted through the adjustment of the thickness of the first electrode layer 18. It may be broken.

As described above, in the present embodiment, the light emitting functional layer 20, the reflective layer 12, and the second electrode layer 22 constitute an optical resonator. That is, the light emitted from the light emitting functional layer 20 is repeatedly reflected between the reflective layer 12 and the second electrode layer 22, so that only light having a specific wavelength component is subjected to amplifying interference, or a resonance phenomenon occurs. Will be involved.
For example, in the light emitting element 2R, the optical distance d _R is, since it is defined by the formula (1), in the light-emitting element 2R, the resonance phenomenon of the light having the wavelength lambda _R occurs. A part of the light having the wavelength λ _R thus amplified (that is, red light) proceeds to the outside of the device because the second electrode layer 22 has a semi-transmissive performance (the second in FIG. 2). (See arrow extending upward beyond electrode layer 22). As a result, red is emphasized.
This also occurs for green and blue.

<Operation effect of organic EL device>
Hereinafter, the operational effects of the organic EL device 1 having the above-described configuration will be described with reference to FIGS. 4 to 7 in addition to FIGS. 1 to 3 already referred to.
First, FIG. 4 and FIG. 5 show various experimental results such as an observation result of light intensity observed in the device 1 by actually manufacturing the organic EL device 1 having the above-described structure. In this experiment, the following assumptions are made.
(I) The reflective layer 12 is made of Al and has a thickness of 100 [nm].
(Ii) The first electrode layer 18 is made of ITO. The thickness is 50 [nm].
(Iii) The total thickness of the light emitting functional layers 20R, 20G, and 20B is 258 [nm], 220 [nm], and 155 [nm], respectively. This includes a hole injection layer thickness of 50 nm and a light emitting layer thickness of 30 nm. These thicknesses are common to all of the light emitting functional layers 20R, 20G, and 20B.
However, the thicknesses of the hole transport layer and the electron transport layer are determined based on the above-described formula (1). Specifically, the hole transport layer in the light emitting functional layer 20R is 136 [nm], the hole transport layer in the light emitting functional layer 20G is 108 [nm], and the hole transport layer in the light emitting functional layer 20B is 60 [nm]. On the other hand, the electron transport layer in the light emitting functional layer 20R is 42 nm, the electron transport layer in the light emitting functional layer 20G is 32 nm, and the electron transport layer in the light emitting functional layer 20B is 15 nm. ]. As described above, in this experimental example, the thickness of the light emitting functional layer 20 is adjusted by adjusting the thicknesses of both the hole transport layer and the electron transport layer.
Moreover, the material which comprises the said light emitting layer also differs according to the light emitting functional layers 20R, 20G, and 20B. The red light emitting layer is obtained by doping the host material BH-215 (made by Idemitsu Kosan Co., Ltd.) with the red dopant material RD-001 (made by Idemitsu Kosan Co., Ltd.), and the green light emitting layer is made by the host material BH-215. A green dopant material GD-206 (manufactured by Idemitsu Kosan Co., Ltd.) doped with (Idemitsu Kosan Co., Ltd.), a blue light-emitting layer, a host material BH-215 (manufactured by Idemitsu Kosan Co., Ltd.) and a blue dopant material BD -102 (made by Idemitsu Kosan Co., Ltd.).
(Iv) The second electrode layer 22 is made of MgAg. The thickness is 10 [nm].
(V) The sealing layer 24 is made of SiON. The thickness is 70 [nm]. Since the sealing layer 24 is formed in common for each of the light emitting elements 2R, 2G, and 2B as described above, the thickness thereof is also common for all the light emitting elements 2.
(Vi) The individual adjustment layer 25 is made of Alq3. Its thickness is, the light-emitting elements 2R, as described above, 2G, depends on 2B, the thickness T _R of the individual adjusting layer 25 of the red response of the light-emitting element for 2R 40 [nm], a green corresponding emission the thickness _{T G} of the individual adjusting layer 25 for element 2R 10 [nm], the thickness _{T B} of the individual adjusting layer 25 of the light emitting element 2R blue corresponding 0 [nm]. That is, the last T _B = 0 means that the individual adjustment layer 25 corresponding to blue does not exist. The present invention includes such a case within the scope thereof.

  FIG. 5 shows the result of actual measurement of the spectrum of light emitted from the light emitting element 2 corresponding to each of red, green, and blue to the outside of the apparatus under such a premise. In FIG. 5, the solid line is a result of reflecting the above-mentioned assumption as it is, and the broken line and the one-point difference line are comparative examples. Here, there are two types of comparative examples, one of which is represented by a one-point difference curve in the figure representing the spectrum of each color. This is an experimental result of the light emitting element in the case where both the sealing layer 24 and the individual adjustment layer 25 according to the present embodiment are not present at all (see the above (v) and (vi)). The other is represented by a dashed curve in the diagram representing the red and green spectra. This is an experimental result of the light-emitting element when the individual adjustment layers 25 for red and green do not exist, but only the sealing layer 24 of the light-emitting element 2 for all colors exists.

  First, in FIG. 5, it is understood that a certain degree of color purity improvement effect is achieved in any curve. As described above, in the organic EL device 1 according to the present embodiment, a resonator including the reflective layer 12, the first electrode layer 18, the light emitting functional layer 20, and the second electrode layer 22 is configured. This is because the above-described equation (1) is satisfied for the resonator.

  According to FIG. 5, the sharpness of the peak is increased as can be seen from the change from the one-point difference line to the solid line in each spectrum. That is, the half width is reduced. From this, it can be seen that the presence of the sealing layer 24 and the individual adjustment layer 25 is more advantageous for improving the color purity than the absence of the sealing layer 24 and the individual adjustment layer 25. In addition, regarding the red and green spectra, as can be seen from the change from the broken line to the solid line, the sharpness of the peak also increases in this respect. That is, for the red and green light-emitting elements 2, it is advantageous for improving the color purity to form the individual adjustment layers 25 having different thicknesses corresponding to the respective colors in addition to the sealing layer 24. I understand that.

The same can be confirmed in FIG. In this figure, the luminous efficiency (unit: cd / A) in each case corresponding to each of the solid line, the broken line, and the one-point difference line in FIG. 5 is shown. It can be seen that the luminous efficiency is higher when the sealing layer 24 or the individual adjustment layer 25 is present than when the sealing layer 24 and the individual adjustment layer 25 are not present (the former is 10.1 [cd / A], the latter being 13.5 or 14.7 [cd / A]). Among them, when both the sealing layer 24 and the individual adjustment layer 25 exist, and the thickness of both layers is 110 [nm], that is, the light emitting element 2R corresponding to the red color. It can be seen that the luminous efficiency is higher in the optimized case than in the other case (that is, when only the sealing layer 24 having a thickness of 70 nm is present) (the former is 13.5 [cd]. / A], the latter 14.7 [cd / A]). Incidentally, high light emission efficiency means that less energy is required to obtain light of the same luminance, which means that the amount of power consumption can be reduced accordingly.
From FIG. 4, it is clear that the same can be said for the light emitting elements 2G and 2B corresponding to green and blue.

The various changes as described above are related to the above-described difference between the experimental example and the comparative example, that is, whether or not the sealing layer 24 or the individual adjustment layer 25 is present.
As described above, in the organic EL device 1 according to the present embodiment, a resonator is formed against the background of the establishment of the above formula (1). In order to suitably draw out the function of this resonator, a resonance phenomenon In other words, there should be an increase in the absolute amount of light. In this regard, in this embodiment, as shown in FIG. 6, first, the light emitted from the light emitting functional layer 20 is strongly reflected at the interface between the light emitting functional layer 20 and the second electrode layer 22 made of an alloy or the like. In addition to this, the light is strongly reflected at each of the interface between the second electrode layer 22 and the sealing layer 24 and the interface between the individual adjustment layer 25 and the inert gas G. That is, the amount of light returned into the resonator increases. This is because a change in the refractive index from the high refractive index layer to the low refractive index layer or vice versa occurs between these interfaces.
Note that, since the refractive index of the sealing layer 24 and the individual adjustment layer 25 are close to each other as described above, strong reflection does not occur at the interface between both layers (24, 25). Further, for the light emitting element 2B corresponding to blue, the individual adjustment layer 25 does not exist in this experimental example (that is, T _B = 0 as described above). The stop layer 24 performs the same function as the reflection enhancement layer 23 that is “an integral of the sealing layer 24 and the individual adjustment layer 25” in the red / green light emitting elements 2 </ b> R and 2 </ b> G. That is, since light is strongly reflected at each of the interface between the second electrode layer 22 and the sealing layer 24 and the interface between the sealing layer 24 and the inert gas G, the light emitting element 2R corresponding to red / green. , 2G, the same effect as that obtained in 2G can also be obtained in the blue light emitting element 2B.
In contrast, when both the sealing layer 24 and the individual adjustment layer 25 are not present, there is strong reflection at the interface between the light emitting functional layer 20 and the second electrode layer 22 as shown in FIG. However, since there is no layer having a relatively higher refractive index on the second electrode layer 22, even if reflection occurs, it becomes considerably weak (see the broken line arrow in the figure). That is, the amount of light returned into the resonator is small compared to the present embodiment.
In this way, according to the present embodiment, various effects as shown in FIGS. 4 and 5 are produced.

  As described above, in the present embodiment or the present experimental example, the “sealing layer 24 and the individual adjustment layer 25” are effective in effectively exerting the resonance action related to the light emitting elements 2R, 2G, and 2B of the respective colors. It is the reflection enhancing layer 23 as an integral part. The total thickness (110 [nm] for red, 80 [nm] for green, and 70 [nm] for blue. Refer to FIG. 4) of the thicknesses of these layers (24, 25) according to this experimental example. It is an example of optimization for. In addition, in this experimental example, the absence of the individual adjustment layer 25 for the light emitting element 2B corresponding to blue is, as it were, only a coincidence, and is not necessarily a consequence. In fact, even if the specific total value of each color is respected, first, the sealing layer 24 having a thickness of 50 [nm] is formed in common for each color, and second, each of red, green, and blue In this regard, even if the individual adjustment layers 25 having a thickness of 60 nm, 30 nm, and 20 nm are formed, 110 nm for red, 80 nm for green, and 70 nm for blue Can be achieved as well.

In this embodiment, in addition to the effects obtained by better drawing out the functions of the optical resonator, such as a color purity improving effect, the following effects are also achieved.
That is, according to the aspect in which the individual adjustment layer 25 adapted to each color is formed after the sealing layer 24 is formed as in this embodiment, the surface of the second electrode layer 22 is contaminated in the manufacturing process. And the risk of causing some damage to the light emitting functional layer 20, particularly the light emitting layer, can be greatly reduced.
This is because, in the present embodiment, the sealing layer 24 having a uniform thickness is formed relatively soon after the formation of the second electrode layer 22. At this time, if it is considered that a SiON layer having a thickness optimized for each color is formed separately for each of the light emitting elements 2R, 2G, and 2B, for example, the SiON layer for the light emitting element 2R corresponding to red is used. During the formation of the layers, the second electrode layer 22 corresponding to the green / blue light emitting elements 2G and 2B is left in a so-called dismissal state, so that the surface of the second electrode layer 22 may be contaminated. Will increase. For the same reason, when the SiON layer corresponding to each color is formed, the light emitting functional layer 20 is likely to be damaged in some way due to the manufacturing process. In the present embodiment, the sealing layer 24 is formed on the second electrode layer 22 relatively quickly, and functions as a protective layer for the second electrode layer 22 and the light emitting functional layer 20. It does not suffer.

  In addition, when the second electrode layer 22 is made of extremely thin MgAg as in the above experimental example, it is difficult to form a film on the second electrode layer 22 by a wet process using this as a base layer. However, as long as the sealing layer 24 having a uniform thickness is formed as in the present embodiment, it is relatively easy to form a film by a wet process using the sealing layer 24 as a base layer. In forming films with different thicknesses on the same plane, the wet process is more suitable than the dry process. From this, in manufacturing the organic EL device 1 having the reflection enhancement layer 23 having a thickness adapted to each color as in the present embodiment, after forming the sealing layer 24 by a dry process, Forming the individual adjustment layers 25 with a thickness corresponding to each color by a wet process provides one of the most reasonable methods. In the present embodiment, such a method can be realized.

As mentioned above, although embodiment concerning this invention was described, the light-emitting device concerning this invention is not limited to the form mentioned above, Various deformation | transformation are possible.
(1) In the above-described embodiment, an example in which the sealing layer 24 is made of SiON and the individual adjustment layer 25 is made of Alq3 is described, but the present invention is not limited to such a form. The “common layer” and the “individual adjustment layer” referred to in the present invention need only be made of “different materials”. Therefore, as long as the conditions are satisfied, basically, any material can be used. May be selected.
However, as can be seen from the above description regarding the experimental example, it is desirable that the refractive indexes of the sealing layer 24 and the individual adjustment layer 25 be as close as possible. Otherwise, there is a high possibility that strong reflection will not occur at either the interface between the second electrode layer 22 and the sealing layer 24 or the interface between the individual adjustment layer 25 and the inert gas G. On the contrary, the possibility that strong reflection occurs at the interface between the sealing layer 24 and the individual adjustment layer 25 is increased, but the “thickness” optimized for both colors is not utilized for each color. ).
In this way, what kind of material should be specifically selected as the “different material” is basically unrestricted. It is preferable to consider the constraints that come from.

  However, it is quite difficult to determine how much the difference in refractive index between the sealing layer 24 and the individual adjustment layer 25 should be specifically suppressed. In general, it can be said that the greater the difference, the less desirable. Also, for the time being, the difference between the refractive index of the sealing layer 24 and the refractive index of the individual adjustment layer 25 and the refractive index of the second electrode layer 22 indicates that the refractive index of the sealing layer 24 and the refractive index of the individual adjustment layer 25 are different. If the condition that it is larger than the difference from the rate is satisfied, the reflection of useless light at the interface between the two layers (24, 25) can be suppressed to a certain extent, and thus the above-mentioned problem may occur. (In addition to or instead of this condition, the difference between the refractive index of the sealing layer 24 and the refractive index of the individual adjustment layer 25 and the refractive index of the inert gas G is The condition that it is larger than the difference between the refractive index of 24 and the refractive index of the individual adjustment layer 25 may be satisfied.)

In this regard, an example in the above-described embodiment, that is, an example in which the sealing layer 24 is made of SiON and the individual adjustment layer 25 is made of Alq3 is helpful. This is because, as described above as the experimental example, in such a case, it has been confirmed that a suitable effect as described with reference to FIGS. 4 and 5 can be obtained. Therefore, there is a reasonable rationality in determining the specific value of the refractive index difference to be satisfied based on this aspect.
FIG. 8 is a graph showing the wavelength dependence of the refractive indexes of SiON and Alq3, and FIG. 9 is a graph showing the difference between both refractive indexes shown in FIG. As shown in these drawings, the difference in refractive index between SiON and Alq3 is about −0.074 to about +0.058 at a wavelength of 400 to 800 [nm] in the visible light region. Therefore, the material to be selected as “different material” preferably satisfies this condition. However, since the above example in which the sealing layer 24 is SiON and the individual adjustment layer 25 is Alq3 is one of the most preferable effects, it is comparable to the effect even when slightly deviating from the conditions. Such an effect is produced.
In consideration of the above points, it is preferable that the difference between the refractive index of the common layer and the refractive index of the individual adjustment layer is within a range of ± 0.1. If a material satisfying such a condition is selected as a material for forming both layers, the effect according to the present embodiment is favorably achieved.

(2) In the above-described embodiment, the case where the light emitting functional layer 20 emits light of each color has been described, but the present invention is not limited to such a form.
For example, in the same manner as the first electrode layer 18 of the above embodiment is formed in common regardless of the light emitting elements 2R, 2G, 2B, the light emitting functional layer is also independent of the light emitting elements 2R, 2G, 2B. It may be formed in common. In this case, the light emitting functional layer is, for example, only one that emits white light. Even in such a case, if an optical resonator structure corresponding to each color as described above is adopted for each light emitting element 2, light of a specific color from white light (for example, as in the above embodiment). It is possible to emphasize only the wavelength components (red light, green light, and blue light) and take them out to the outside.

<Application>
Next, electronic devices to which the light emitting device according to the present invention is applied will be described.
FIG. 10 is a perspective view illustrating a configuration of a mobile personal computer using the light emitting device according to the above-described embodiment as an image display device. The personal computer 2000 includes an organic EL device 1 as a display device and a main body 2010. The main body 2010 is provided with a power switch 2001 and a keyboard 2002.
FIG. 11 shows a mobile phone to which the light emitting device according to the above embodiment is applied. The cellular phone 3000 includes a plurality of operation buttons 3001, scroll buttons 3002, and the organic EL device 1 as a display device. By operating the scroll button 3002, the screen displayed on the organic EL device 1 is scrolled.
FIG. 12 shows an information portable terminal (PDA: Personal Digital Assistant) to which the light emitting device according to the embodiment is applied. The information portable terminal 4000 includes a plurality of operation buttons 4001, a power switch 4002, and the organic EL device 1 as a display device. When the power switch 4002 is operated, various types of information such as an address book and a schedule book are displayed on the organic EL device 1.

  Electronic devices to which the light emitting device according to the present invention is applied include those shown in FIGS. 10 to 12, digital still cameras, televisions, video cameras, car navigation devices, pagers, electronic notebooks, electronic papers, calculators, word processors. , Workstations, videophones, POS terminals, video players, devices with touch panels, and the like.

DESCRIPTION OF SYMBOLS 1 ... Organic EL device (light emitting device), 2 (2R, 2G, 2B) ... Light emitting element, 3 ... Light emitting panel, 10 ... Substrate, 12 ... Reflective layer, 18 ... First electrode layer, 20 (20R, 20G, 20B) ... light emitting functional layer, 22 ... second electrode layer (translucent semi-reflective layer), 23 ... reflection enhancing layer, 25 ... sealing layer, G ... inert gas

Claims (7)

A light emitting device having a first electrode layer, a second electrode layer, and a light emitting functional layer disposed between the first and second electrode layers;
A reflective layer that reflects the light emitted from the light emitting functional layer toward the light emitting functional layer;
A translucent translucent layer disposed on the opposite side of the reflective layer across the light emitting functional layer, reflecting a part of the light emitted from the light emitting functional layer toward the light emitting functional layer and transmitting the other part. A reflective layer;
A reflection enhancing layer disposed on the opposite side of the reflective layer from the semitransparent semireflective layer and in contact with the semitransparent semireflective layer;
With
The light emitting element is
Including those emitting red light, emitting green light, and emitting blue light,
The reflection enhancement layer is
A common layer formed with a uniform thickness regardless of the light emitting element emitting red light, the light emitting element emitting green light, and the light emitting element emitting blue light;
Corresponding to each of the light emitting element emitting red light, the light emitting element emitting green light, and the light emitting element emitting blue light, an individual adjustment layer made of a material different from the common layer and having a different thickness,
A light emitting device comprising: The light emitting element, the reflective layer, the semitransparent semireflective layer, and the reflection enhancement layer are constructed so as to form a laminated structure on a substrate,
The first electrode layer is closer to the substrate as viewed from the second electrode layer;
The translucent semi-reflective layer includes the second electrode layer and functions as a cathode;
The reflection enhancement layer is
The common layer is in contact with the translucent transflective layer,
In contact with the translucent semi-reflective layer,
The light-emitting device according to claim 1. The refractive index of the common layer and the refractive index of the individual adjustment layer included in the reflection enhancement layer are:
Higher than the refractive index of the translucent semi-reflective layer,
The light-emitting device according to claim 2. The light emitting device, the reflective layer, the translucent semi-reflective layer, and the reflection enhancement layer further comprises a storage can that fits in a space filled with an inert gas,
The reflection enhancing layer is in contact with the inert gas; and
The refractive index of the common layer and the refractive index of the individual adjustment layer included in the reflection enhancement layer are:
Higher than the refractive index of the inert gas,
The light-emitting device according to claim 2 or 3. The difference between the refractive index of the common layer and the refractive index of the individual adjustment layer included in the reflection enhancement layer, and the refractive index of the translucent semi-reflective layer,
Greater than the difference between the refractive index of the common layer and the refractive index of the individual adjustment layer,
The light-emitting device according to claim 3. The optical distance from the reflective layer to the interface facing the reflective layer in the translucent semi-reflective layer is determined based on d calculated by the formula (i). The light emitting device according to any one of the above.
d = ((2πm + φ _D + φ _U ) / 4π) · λ (i)
here,
λ is the wavelength set as the resonance target,
phi _D, the light of wavelength λ traveling to the reflective layer from the light-emitting functional layer side, a phase change when reflected by the reflective layer,
φ _U is a phase change when light of wavelength λ traveling from the light emitting functional layer side to the semitransparent semireflective layer is reflected by the translucent semireflective layer,
m is a positive integer. The light-emitting device according to claim 1 is provided.
An electronic device characterized by that.

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