JP3726789B2 - Organic EL display - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an organic EL display that is high-definition, excellent in environmental resistance and productivity, and applicable to a wide range of uses such as displays of portable terminals and industrial measuring instruments.
[0002]
[Prior art]
In recent years, the speed of information communication and the application range have been rapidly increasing. Among these, a high-definition display device having low power consumption and high-speed response capable of meeting the demands of portability and moving image display has been widely used.
In particular, a color display device of a driving method (active matrix driving method) using a thin film transistor (TFT) has been devised for the colorization method. In this case, in the method of extracting light to the substrate side on which the TFT is formed, the aperture ratio does not increase due to the light shielding effect of the wiring portion, and recently, the light is emitted to the side opposite to the substrate on which the TFT is formed. A so-called top emission method has been devised.
[0003]
Even in the case of the top emission method, the three primary light emitting materials of red, blue, and green must be separated and arranged in a matrix, because the three types of light-emitting materials for RGB must be arranged in a high-definition matrix. It is difficult to manufacture efficiently and cheaply, and at the same time, because the luminance change characteristics and driving conditions of the three light emitting materials are different, it is difficult to ensure color reproducibility for a long time. It remains unsolved.
[0004]
Even when a color filter is used for a backlight that emits white light and the three primary colors are transmitted and separated, there still remains a problem of improving the efficiency of the backlight.
In the color conversion method that absorbs the phosphors separately arranged and emits multiple colors of fluorescent light from each phosphor, the top emission method using the TFT drive method is adopted to achieve a higher definition and higher brightness organic EL display. Have the potential to provide.
[0005]
The color display device disclosed in Japanese Patent Laid-Open Nos. 11-251059 and 2000-77191 is an example of such a system.
FIG. 2 is a schematic cross-sectional view showing the structure of an organic EL display according to the prior art (in the case of an active matrix driving method).
On the substrate 1, a TFT 2 (thin film transistor: hereinafter referred to as TFT), an anode 3, an organic EL light emitting layer 4, and a cathode 5 are formed. Subsequently, a color filter 12 and a black mask 13 are formed on the transparent substrate 11. Next, the sealing agent 31 is formed on the periphery of the substrate 1 using, for example, a room temperature curable two-component epoxy adhesive, and is bonded to the transparent substrate 11. At this time, an internal space 32 is formed between the two substrates. The curing time of the sealing layer 31 requires a considerably long time of 24 hours at room temperature, and when the alignment of the organic EL light emitting layer and the color filter is performed, it is necessary to fix and prevent misalignment during the room temperature curing. was there.
[0006]
In a color display using a color filter as shown in FIG. 2, an important practical issue is a fine color display function, and the organic EL element has long-term stability including color reproducibility. Furthermore, it has a structure and a sealing method that can be manufactured in a short time.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the organic EL display of the present invention comprises:
An organic light emitting device formed by laminating a first electrode made of a conductive thin film material formed on a substrate, an organic EL light emitting layer, a second electrode made of a transparent conductive material, and a protective layer, and a transparent substrate In the organic EL element for sealing and bonding the laminate having the color filter and the black mask formed on the organic EL light emitting layer and the position of the color filter,
The sealant used between the two substrates to be sealed and bonded is the sealant outer peripheral portion located on the outer periphery between the substrates, and the seal placed inside the sealant outer peripheral portion and filled between the substrates The sealing agent is an acrylic adhesive having an ultraviolet curing function and a room temperature curing function, and the outer periphery of the sealing agent is cured by ultraviolet rays, and the inside of the sealing agent not irradiated with ultraviolet rays is at room temperature. It will be cured .
[0008]
The present invention has been made in view of the above-described drawbacks. The organic EL light-emitting layer and the color filter are accurately aligned, and a short-time curing method and a light from the organic EL light-emitting layer are provided. Provided are an organic EL element sealing structure and a sealing method capable of effectively transmitting light to a color filter without reflecting light, preventing intrusion of moisture and the like from the external environment, and maintaining stable light emission characteristics over a long period of time. There is.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the organic EL display of the present invention comprises:
An organic light emitting device formed by laminating a first electrode made of a conductive thin film material formed on a substrate, an organic EL light emitting layer, a second electrode made of a transparent conductive material, and a protective layer, and a transparent substrate In the organic EL element for sealing and bonding the laminate having the color filter and the black mask formed on the organic EL light emitting layer and the position of the color filter,
An acrylic adhesive having an ultraviolet curing function and a room temperature curing function is used as a sealant used between two substrates to be sealed and bonded.
[0010]
Here, the refractive index of the acrylic adhesive is preferably 1.2 to 2.5.
In the present invention, by using the adhesive having the above two curing functions, the organic EL light-emitting layer and the color filter are accurately aligned at the outer periphery of the sealant, and the ultraviolet curing is performed in a short time. Is granted.
About the inside of a sealing layer, the function from which a refractive index is high in order to transmit the light from an organic electroluminescent light emitting layer to a color filter, and the function hardened | cured at room temperature since ultraviolet curing is impossible.
[0011]
JP-A-2001-237066 discloses that an ultraviolet curable resin may be used as an adhesive and a room temperature curable two-component mixed resin may be used. However, this disclosure discloses the use of either of two types of resins, and does not suggest the use of an adhesive having both two types of functions as in the present invention. The present invention is characterized in that an acrylic adhesive having both an ultraviolet curing function and a room temperature curing function is used.
[0012]
The reason for this is that in order to align and seal the two substrates, after the entire surface is bonded with one adhesive, the resin curing of the outer peripheral portion after the alignment is completed is completed in a short time. In order to prevent misalignment, the UV curing function is used, and it is difficult to irradiate the resin (adhesive) inside the device with UV light. To complete.
[0013]
In the present invention, the organic EL display may be active matrix drive or passive matrix drive. In the case of performing active matrix driving, for example, the anode on the lower side (substrate side) may be divided for each light emitting portion and connected to the source of a TFT (thin film transistor) provided on the substrate. At this time, the cathode of the upper electrode (on the side opposite to the substrate) can be a uniform electrode. Here, as a configuration in which the substrate-side electrode is used as a cathode and the non-substrate-side electrode is used as an anode, the TFT may be connected. On the other hand, when passive matrix driving is performed, it is possible to adopt a configuration in which the lower electrode (substrate side) and the upper electrode (non-substrate side) have line patterns extending in directions orthogonal to each other. In the case of active matrix driving, the substrate itself may be a TFT substrate on which driving TFTs are already formed. In addition, when a passive matrix driving element is formed, a glass substrate or a plastic substrate can be used.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The organic EL display of the present invention will be described with reference to FIG.
Moreover, it describes below about the material of each part which comprises an organic EL element.
1: TFTs are arranged in a matrix on an insulating substrate made of a substrate, a thin film transistor (TFT), anode glass, plastic, or the like, or a substrate having an insulating thin film formed on a semiconductive or conductive substrate. The source electrode is connected to the anode which is the first electrode corresponding to the above.
[0015]
The TFT is a bottom gate type in which a gate electrode is provided under a gate insulating film, and has a structure using a polycrystalline silicon film as an active layer.
The anode is formed on a planarization insulating film formed on the TFT. In a normal organic EL display, ITO which is transparent and has a high work function is used as an anode material. In the case of top emission, a metal electrode (Al, Ag, Mo, W) having a high reflectance is used under the ITO.
2: A TFT electrode substrate on which an organic light emitting element TFT and an anode are patterned, an organic EL light emitting layer, and a cathode that is a second electrode are provided. That is, in the case of the color conversion method, the above-mentioned color filter layer alone or the color filter layer and the fluorescent color conversion layer or the color filter layer emit light in the near ultraviolet to visible region, preferably blue to blue-green region, emitted from the organic light emitting element. And the fluorescent color conversion layer. The organic light emitting device has a structure in which an organic EL light emitting layer is sandwiched between a pair of electrodes, and a hole injection layer or an electron injection layer is interposed as required. Specifically, those having the following layer structure are employed. Here, an example is described in which the first electrode on the substrate side is the anode, but it goes without saying that the substrate side may be the cathode.
(1) Anode / organic light emitting layer / cathode
(2) Anode / hole injection layer / organic EL light emitting layer / cathode
(3) Anode / organic EL light emitting layer / electron injection layer / cathode
(4) Anode / hole injection layer / organic EL light emitting layer / electron injection layer / cathode
(5) Anode / hole injection layer / hole transport layer / organic EL light emitting layer / electron injection layer / cathode In the top emission color conversion system of this embodiment, in the above layer configuration, the cathode is the organic EL light emitting layer. It is necessary to be transparent in the wavelength range of light emitted from the light source, and light is emitted through the transparent cathode.
[0016]
Transparent cathodes include alkali metals such as lithium and sodium, alkaline earth metals such as potassium, calcium, magnesium and strontium, or electron injecting metals such as fluorides thereof, alloys and compounds with other metals The ultrathin film (10 nm or less) is used as an electron injection layer, and a transparent conductive film such as ITO or IZO is formed thereon.
[0017]
As the material of each layer of the organic EL light emitting layer, known materials are used. For example, in order to obtain blue to blue-green light emission as an organic light emitting layer, for example, a fluorescent brightener such as benzothiazole, benzimidazole, benzoxazole, metal chelated oxonium compound, styrylbenzene compound, aromatic Dimethylidin compounds and the like are preferably used.
3: Color conversion layer 1) Organic fluorescent dye In the present invention, as the organic fluorescent dye, different visible light is absorbed by absorbing light in the near ultraviolet region or visible region, particularly blue or blue-green region emitted from the light emitting element. However, it is preferable that at least one fluorescent dye that emits fluorescence in the red region is used, and it may be combined with one or more fluorescent dyes that emit fluorescence in the green region. That is, it is easy to obtain an organic EL light emitting element that emits light in the blue to blue-green region. However, if this is changed to light in the red region through a simple red filter, the wavelength of the red region is originally obtained. Because there is little light, it becomes extremely dark output light.
[0018]
Accordingly, the light in the red region can be output with sufficient intensity by converting the light from the element into light in the red region by the fluorescent dye. On the other hand, the light in the green region may be output by converting the light from the element into light in the green region by another organic fluorescent dye, or the light emitted from the device is green. If the area contains enough light, the light from the element may simply be output through a green filter. On the other hand, with respect to the light in the blue region, the light from the organic light emitting element can be output through a simple blue filter.
[0019]
Examples of fluorescent dyes that absorb light in the blue to blue-green region emitted from the light emitter and emit red region fluorescence include rhodamine B, rhodamine 6G, rhodamine 3B, rhodamine 101, rhodamine 110, sulforhodamine, basic violet 11, Rhodamine dyes such as basic red 2, cyanine dyes, pyridine dyes such as 1-ethyl-2- [4- (p-dimethylaminophenyl) -13-butadienyl] -pyridium-perchlorate (pyridine 1), or And oxazine dyes. Furthermore, various dyes (direct dyes, acid dyes, basic dyes, disperse dyes, etc.) can be used if they are fluorescent.
[0020]
Examples of fluorescent dyes that absorb blue to blue-green light emitted from a light emitter and emit green light include 3- (2′-benzothiazolyl) -7-diethylaminocoumarin (coumarin 6), 3- (2 '-Benzimidazolyl) -7-N, N-diethylaminocoumarin (coumarin 7), 3- (2'-N-methylbenzimidazolyl) -7-N, N-diethylaminocoumarin (coumarin 30), 2, 3, 5, 6 -1H, 4H-tetrahydro-8-trifluoromethylquinolidine (9,9a, 1-gh) coumarin (coumarin 153) and other coumarin dyes, or basic yellow 51 which is a coumarin dye dye, and solvent yellow 11 And naphthalimide dyes such as Solvent Yellow 116. Furthermore, various dyes (direct dyes, acid dyes, basic dyes, disperse dyes, etc.) can be used if they are fluorescent.
[0021]
The organic fluorescent dye used in the present invention is a polymethacrylate, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer resin, alkyd resin, aromatic sulfonamide resin, urea resin, melamine resin, benzoguanamine resin, and these resins. An organic fluorescent pigment may be obtained by kneading into a mixture or the like in advance to obtain a pigment. In addition, these organic fluorescent dyes and organic fluorescent faces may be used alone or in combination of two or more in order to adjust the hue of fluorescence. The organic fluorescent dye used in the present invention is contained in the fluorescent color conversion film in an amount of 0.01 to 5% by weight, more preferably 0.1 to 2% by weight, based on the weight of the conversion film. If the content of the organic fluorescent dye is less than 0.01% by weight, sufficient wavelength conversion cannot be performed, or if the content exceeds 5%, color conversion is performed due to effects such as concentration quenching. Resulting in reduced efficiency.
2) Matrix resin Next, the matrix resin used in the fluorescent color conversion film of the present invention is a photocurable or photothermal combination type curable resin that is exposed to light and / or heat to generate radical species or ion species. Polymerized or cross-linked and insoluble and infusible. Further, it is not necessary to be soluble in an organic solvent or an alkali solution before curing, which is essential when patterning is performed by a conventional photolithography method.
[0022]
Specifically, the photocurable or photothermal combination type curable resin is (1) a composition film composed of an acrylic polyfunctional monomer and oligomer having a plurality of acryloyl groups and methacryloyl groups, and light or a thermal polymerization initiator. Heat treated to generate photoradicals and heat radicals to polymerize, (2) A composition comprising polyvinyl cinnamate ester and sensitizer dimerized by light or heat treatment, and (3) chain A composition film comprising a olefin or a cyclic olefin and a bisazide is generated by nitrene generation by light or heat treatment and crosslinked with an olefin, and (4) a composition film comprising a monomer having an epoxy group and a photoacid generator is subjected to light or heat treatment. In other words, the acid (cation) is generated and polymerized. In particular, the photocurable or photothermal combination type curable resin (1) can be patterned with high definition, and is preferable in terms of reliability such as solvent resistance and heat resistance.
3) Shape As the shape of the color conversion layer, a stripe pattern separated for each color is well known, but in order to improve the effect of the visible light reflection wall, it is separated not only for each color but also for each sub-pixel. It is more preferable to have a different structure. Further, by taking the peripheral portion of the color conversion layer into a forward tapered shape, the extraction efficiency is further improved. However, if the forward taper angle χ is too small, the light reflected by the reflective layer is directed laterally and cannot be extracted. Therefore, an angle of about 45 ° is preferable. 4) Color filter layer color conversion When sufficient color purity cannot be obtained with only a layer, a laminate of a color filter layer and the color conversion layer is formed. The thickness of the color filter layer is preferably 1 to 1.5 μm.
4: Passivation layer (protective layer)
The passivation layer has high transparency in the visible region (transmittance of 50% or more in the range of 400 to 700 nm), Tg of 100 ° C. or more, surface hardness of 2H or more in pencil hardness, and a smooth coating film on the color conversion layer Any material can be used as long as it does not deteriorate the functions of the color conversion layers 2 to 4, and examples thereof include imide-modified silicone resins (JP-A-5-134112, etc.), inorganic metal compounds (TiO, AL ₂ O _3). SiO ₂ etc.) are dispersed in acrylic, polyimide, silicone resin, etc. (JP-A-5-119306 etc.), and epoxy-modified acrylate resin (JP-A-7-48424) as an ultraviolet curable resin. Resin having a reactive vinyl group of acrylate monomer / oligomer / polymer, resist resin (JP-A-6-300910, etc.), sol-gel method Photo-curing resins such as organic compounds (described in monthly display 1997, Vol. 3, No. 7, JP-A-8-27934, etc.), fluorine-based resins (JP-A-5-36475, etc.) and / or thermosetting Mold resin.
[0023]
The method for forming the passivation layer is not particularly limited. For example, dry methods (sputtering method, vapor deposition method, CVD method, etc.) and wet methods (spin coating method, roll coating method, casting method, etc.) are commonly used. This method can be used.
Moreover, as a passivation layer, it has electrical insulation, has a barrier property against moisture and low molecular components, and has high transparency in the visible range (transmittance of 50% or more in the range of 400 to 700 nm), preferably 2H or more. A material having film hardness may be used.
[0024]
For example, inorganic oxides such as SiOx, SiNx, SiNxOy, AlOx, TiOx, TaOx, and ZnOx, inorganic nitrides, and the like can be used. There is no restriction | limiting in particular as a formation method of this passivation layer, It can form by usual methods, such as a sputtering method, CVD method, a vacuum evaporation method, a dip method. The above-mentioned passivation layer may be a single layer, but the effect is greater when a plurality of layers are laminated. The thickness of the laminated passivation layer is preferably 1 to 10 μm.
5: Sealant As the sealant, an adhesive having two functions of an ultraviolet curing function and a room temperature curing function is used.
[0025]
This adhesive is achieved, for example, by adding a photocuring catalyst and imparting an ultraviolet curing function based on an acrylic two-component mixed adhesive. The ultraviolet curing function is designed so that curing is completed at a wavelength of 365 nm and an irradiation amount of 3000 to 10,000 mJ / cm ² with respect to the ultraviolet irradiation condition. If it demonstrates in detail about an irradiation amount, it will be achieved by irradiating for 30 to 100 seconds with the illumination intensity of 100 mW / cm < ² >.
[0026]
When the illuminance is 400 mW / cm ² or less and 50 mW / cm ² or more, stable curing can be obtained. At 400 mW / cm ² or more, the reaction is intense and causes an exothermic reaction. Also, no reaction occurs at 50 mW / cm ² or less. Good illuminance is around 100 mW / cm ² .
As a specific adhesive, an ultraviolet curable two-component mixed acrylic adhesive, trade name DX-1013U manufactured by Toyo Ink Co., Ltd. can be used.
[0027]
As the room temperature curing function of this adhesive, curing is completed in about 40 to 50 minutes at room temperature (20 to 28 ° C.) after mixing.
(Example 1)
As shown in FIG. 1, a TFT 2, an anode 3, an organic EL light emitting layer 4, a cathode 5, and a protective layer 6 are sequentially formed on a glass substrate 1. Next, a color filter 12 and a black mask 13 are sequentially formed on the transparent glass substrate 11. The following steps are performed on the two substrates thus formed in a dry nitrogen atmosphere (both oxygen and moisture concentrations of 1 ppm or less) in the glove box.
[0028]
Weighed / mixed / defoamed UV curable acrylic adhesive (trade name DX-1013U manufactured by Toyo Ink Co., Ltd.) with a two-component mixed room temperature curing function at a volume ratio of 1: 1, and then dispensed with organic dispenser on the side of organic EL After applying a necessary amount on the glass substrate 1, the transparent glass substrate 11 on the color filter side is bonded. In this case, the distance between the two substrates to be bonded is 5 μm to 50 μm, and the amount of the necessary sealant can be calculated from the area.
[0029]
Thereafter, alignment is performed in correspondence with the organic EL light emitting layer 4 and the color filter 12, and curing is performed by irradiating the sealant outer peripheral portion with an illuminance of 100 mW / cm ² for 30 seconds as an ultraviolet curing condition.
About the inside of the sealant which cannot be cured by ultraviolet rays, curing is completed in about 40 to 50 minutes at room temperature.
[0030]
The refractive index of the two-component mixed type room temperature curing UV curing acrylic adhesive (product name DX-1013U manufactured by Toyo Ink Co., Ltd.) is 1.43 and no light reflection occurs. Can be transmitted to the color filter 12. In addition, the invasion of moisture from the external environment is prevented, and a long-term reliable organic EL element is configured.
In the case of passive matrix driving, this is a step of aligning the intersection of the line patterns of the two electrodes and the color conversion filter layer.
[0031]
【The invention's effect】
As mentioned above, according to the present invention,
An organic light emitting device formed by laminating a first electrode made of a conductive thin film material formed on a substrate , an organic EL light emitting layer, a second electrode made of a transparent conductive material, and a protective layer, and a transparent substrate In the organic EL element for sealing and bonding the laminate having the color filter and the black mask formed on the organic EL light emitting layer and the position of the color filter,
The sealant used between the two substrates to be sealed and bonded is the sealant outer peripheral portion located on the outer periphery between the substrates, and the seal placed inside the sealant outer peripheral portion and filled between the substrates The sealing agent is an acrylic adhesive having an ultraviolet curing function and a room temperature curing function, and the outer periphery of the sealing agent is cured by ultraviolet rays, and the inside of the sealing agent not irradiated with ultraviolet rays is at room temperature. It was decided to be cured .
[0032]
By using the adhesive having the above two curing functions, the sealant outer peripheral portion is provided with a function of accurately aligning the organic EL light emitting layer and the color filter and curing the ultraviolet rays in a short time.
About the inside of a sealing layer, the function from which refractive index is high in order to transmit the light from an organic electroluminescent light emitting layer to a color filter, and the function hardened | cured at room temperature since ultraviolet rays cannot be hardened | cured are provided.
[0033]
Also, for the inside of the sealing layer, by using a sealing agent having a refractive index of 1.3 to 2.5, a structure that prevents reflection of light from the organic EL light emitting layer and effectively transmits it to the color filter is achieved. At the same time, it is possible to prevent moisture and the like from entering from the outside environment and maintain stable light emission characteristics over a long period of time.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing the structure of an organic EL display of the present invention.
FIG. 2 is a schematic cross-sectional view showing the structure of a conventional organic EL display.
[Explanation of symbols]
1 substrate 2 TFT
3 anode 4 organic EL light emitting layer 5 cathode 6 protective layer 11 transparent substrate 12 color filter 13 black mask 21 outer periphery sealing layer 22 inner sealing layer 31 sealing layer 32 inner space

Claims (2)

An organic light emitting device formed by laminating a first electrode made of a conductive thin film material formed on a substrate, an organic EL light emitting layer, a second electrode made of a transparent conductive material, and a protective layer, and a transparent substrate In the organic EL element for sealing and bonding the laminate having the color filter and the black mask formed on the organic EL light emitting layer and the position of the color filter,
The sealant used between the two substrates to be sealed and bonded is the sealant outer periphery located on the outer periphery between the substrates, and the seal that is located inside the sealant outer periphery and filled between the substrates The sealant is an acrylic adhesive having an ultraviolet curing function and a room temperature curing function, the outer periphery of the sealant is cured by ultraviolet rays, and the interior of the sealant that is not irradiated with ultraviolet rays is at room temperature. An organic EL display which is cured . 2. An organic EL display using an acrylic adhesive having a refractive index of 1.2 to 2.5 and an ultraviolet curing function and a room temperature curing function as the sealant according to claim 1.

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