JP2002319494A - El element with photocatalyst-containing layer and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an EL element which can be manufactured with more ease and its manufacturing method. SOLUTION: The element consists of at least a base body, a transparent first electrode formed on the base body, a hole carrier layer formed on the first electrode, a photocatalyst-containing layer formed on the hole carrier layer, a light-emitting layer formed on the photocatalyst layer, and a second electrode formed on the light-emitting layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an EL (electroluminescence) device, and more particularly to an organic thin film EL device used for a display device.

[0002]

2. Description of the Related Art Attention has been paid to the use of EL elements as self-luminous planar display elements. Among them, an organic thin-film EL display using an organic substance as a light-emitting material has high luminous efficiency, such as realizing high-luminance light emission even at an applied voltage of slightly less than 10 V, and can emit light with a simple element structure. Is expected to be applied to advertisements for displaying the pattern of light emission and other low-cost displays for simple displays.

However, in actually manufacturing a display using EL elements, it is necessary to pattern electrodes and an organic EL layer, and typically requires a photolithography process and a patterning process using a complicated pattern film forming apparatus. However, this complicates the process and increases the cost. Further, in the method of patterning the organic EL material by mask vapor deposition, a high-priced vacuum apparatus is required, and the yield and the use efficiency of the expensive EL material are poor, resulting in cost. On the other hand, a method of forming a pattern by an inkjet method is as follows.
Although the process is relatively simple, there are problems in terms of yield and film thickness uniformity. Further, when various shapes and large areas are required such as an EL element for advertisement, there is a problem that productivity is remarkably reduced.

As described above, in the production of an EL element, particularly, an organic EL display, the number of steps becomes very large in order to perform patterning of electrodes, organic EL layers, insulating layers, and the like, resulting in an increase in yield, productivity, and cost. Face big challenges.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an EL device which can be manufactured more easily and a method for manufacturing the same.

[0006]

Means for Solving the Problems The present inventors have solved the above-mentioned problems by forming a pattern based on the difference in wettability by patternwise exposing a photocatalyst-containing layer and forming a light-emitting layer using the pattern. The inventors have found that the present invention can be solved and completed the present invention.

Therefore, the EL device of the present invention comprises a base, a transparent first electrode formed on the base, a hole transport layer formed on the first electrode, , A light-emitting layer formed on the photocatalyst-containing layer, and a second electrode formed on the light-emitting layer.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION EL element As described above, the EL element of the present invention comprises at least a substrate, a transparent first electrode, a hole transport layer, a photocatalyst containing layer, a light emitting layer, and a second electrode. Are laminated. The EL device of the present invention can include any layer that is usually used for an EL device. In addition, it is preferable that the EL element is a display of full color display in which fine pixels are patterned, because the effect of the present invention is large.

Photocatalyst-Containing Layer (Photocatalyst-Containing Layer) In the present invention, the photocatalyst-containing layer means a layer whose wettability can be changed in the future by light irradiation and a layer which has already changed. The photocatalyst may be any substance that causes such a change. By exposing the photocatalyst-containing layer in a pattern, a pattern due to a change in wettability can be formed. Typically, the area not irradiated with light is water repellent,
The site irradiated with light becomes highly hydrophilic. In the present invention,
The pattern of the light emitting layer provided on the photocatalyst containing layer can be easily formed with high quality by utilizing the pattern due to the difference in wettability of the surface of the photocatalyst containing layer.

The photocatalyst-containing layer of the present invention preferably has a work function that changes according to the amount of light to be irradiated. Such a photocatalyst containing layer, by adjusting the amount of light irradiation, can appropriately change the work function, the work function of the photocatalyst containing layer by adjusting the amount of light irradiation is larger than the hole transport layer, smaller than the light emitting layer. By adjusting the value to the value, the injection of electric charge can be promoted, and the luminous efficiency of the EL element can be increased.

In addition, the hole transport layer is often made of a material which is sensitive to ultraviolet rays. When such a hole transport layer is used, it is preferable that the photocatalyst-containing layer contains an ultraviolet absorber and the hole transport layer is made of an ultraviolet ray. Can be protected from irradiation.

If the thickness of the photocatalyst-containing layer is too small, the difference in wettability does not clearly appear and patterning becomes difficult. If the thickness is too large, the transport of holes or electrons is hindered.
Since the light emission of the L element is adversely affected, preferably 50 to
2000 °, more preferably 300 to 1000 °.

(Principle of Change in Wettability) In the present invention,
Using a photocatalyst capable of causing a chemical change in a nearby substance (such as a binder) by light irradiation, a pattern due to a difference in wettability is formed in a portion irradiated with light. The mechanism of action by the photocatalyst is not always clear, but the carrier generated in the photocatalyst by light irradiation directly changes the chemical structure of the binder or the like, or the active oxygen species generated in the presence of oxygen or water binds the binder. It is considered that the surface wettability changes by changing the chemical structure such as the above.

(Photocatalyst Material) Examples of the photocatalyst material used in the present invention include titanium oxide (TiO ₂ ), zinc oxide (ZnO), tin oxide (SnO ₂ ) and strontium titanate (SrTi) which are known as optical semiconductors.
Metal oxides such as O ₃ ) / tungsten oxide (WO ₃ ), bismuth oxide (Bi ₂ O ₃ ), and iron oxide (Fe ₂ O ₃ ) can be given, and titanium oxide is particularly preferred. Titanium oxide has a high band gap energy,
It is advantageous in that it is chemically stable, has no toxicity, and is easily available.

As titanium oxide as a photocatalyst, both anatase type and rutile type can be used, but anatase type titanium oxide is preferable. Specifically, for example, anatase titania sol of peptic hydrochloride type (Ishihara Sangyo Co., Ltd., STS-02, average crystallite diameter 7 nm), anatase titania sol of nitric acid deflocculation type (Nissan Chemical, TA-
15, average crystallite diameter of 12 nm).

The amount of the photocatalyst in the photocatalyst-containing layer is 5 to 60.
% By weight, and more preferably 20 to 40% by weight.

(Binder Component) The binder that can be used in the photocatalyst-containing layer of the present invention preferably has a high binding energy such that the main skeleton is not decomposed by the photoexcitation of the photocatalyst. Examples include organopolysiloxanes that exhibit large strength by hydrolyzing and polycondensing chloro or alkoxysilanes by reaction or the like, or (2) organopolysiloxanes obtained by crosslinking reactive silicones having excellent water repellency and oil repellency. Can be.

In the case of the above (1), the general formula Y _n SiX
One or more hydrolyzed condensates and co-hydrolyzed compounds of the silicon compound represented by _4-n (n = 1 to 3) can be the main component. In the above general formula, Y can be, for example, an alkyl group, a fluoroalkyl group, a vinyl group, an amino group or an epoxy group, and X is, for example, a halogen,
It can be a methoxyl, ethoxyl, or acetyl group.

Specifically, methyltrichlorosilane, methyltribromosilane, methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, methyltri-t-butoxysilane; ethyltrichlorosilane, ethyltribromosilane, ethyltrichlorosilane Methoxysilane, ethyltriethoxysilane, ethyltriisopropoxysilane, ethyltri-t-butoxysilane; n
-Propyltrichlorosilane, n-propyltribromosilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, n-propyltriisopropoxysilane, n-propyltri-t-butoxysilane; n-
Hexyltrichlorosilane, n-hexyltribromosilane, n-hexyltrimethoxysilane, n-hexyltriethoxysilane, n-hexyltriisopropoxysilane, n-hexyltri-t-butoxysilane; n-decyltrichlorosilane, n-decyl Tribromosilane,
n-decyltrimethoxysilane, n-decyltriethoxysilane, n-decyltriisopropoxysilane, n-
Decyltri-t-butoxysilane; n-octadecyltrichlorosilane, n-octadecyltribromosilane, n
-Octadecyltrimethoxysilane, n-octadecyltriethoxysilane, n-octadecyltriisopropoxysilane, n-octadecyltri-t-butoxysilane; phenyltrichlorosilane, phenyltribromosilane, phenyltrimethoxysilane, phenyltriethoxysilane, phenyl Triisopropoxysilane, phenyltri-t-butoxysilane; tetrachlorosilane, tetrabromosilane, tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, dimethoxydiethoxysilane; dimethyldichlorosilane, dimethyldibromosilane, dimethyldimethoxysilane , Dimethyldiethoxysilane; diphenyldichlorosilane, diphenyldibromosilane, diphenyldimethoxysilane, diphenyldiethoxysilane Phenyl methyldichlorosilane,
Phenylmethyldibromosilane, phenylmethyldimethoxysilane, phenylmethyldiethoxysilane; trichlorohydrosilane, tribromohydrosilane, trimethoxyhydrosilane, triethoxyhydrosilane, triisopropoxyhydrosilane, tri-t-butoxyhydrosilane; vinyltrichlorosilane, vinyltribromo Silane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, vinyltrit
-Butoxysilane; trifluoropropyltrichlorosilane, trifluoropropyltribromosilane, trifluoropropyltrimethoxysilane, trifluoropropyltriethoxysilane, trifluoropropyltriisopropoxysilane, trifluoropropyltri-t-butoxysilane; γ- Glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ
Glycidoxypropyltriisopropoxysilane, γ
-Glycidoxypropyltri-t-butoxysilane; γ-
Methacryloxypropylmethyldimethoxysilane, γ
-Methacryloxypropylmethyldiethoxysilane,
γ-methacryloxypropyltrimethoxysilane, γ
-Methacryloxypropyltriethoxysilane, γ-
Methacryloxypropyltriisopropoxysilane,
γ-methacryloxypropyltri-t-butoxysilane; γ-aminopropylmethyldimethoxysilane, γ-
Aminopropylmethyldiethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltriisopropoxysilane, γ-aminopropyltri-t-butoxysilane;
γ-mercaptopropylmethyldimethoxysilane, γ-
Mercaptopropylmethyldiethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropyltriisopropoxysilane, γ-mercaptopropyltri-t-butoxysilane; β- (3,4-epoxy Cyclohexyl) ethyltrimethoxysilane, β- (3,4-epoxycyclohexyl) ethyltriethoxysilane; and partial hydrolysates thereof; and mixtures thereof.

As the binder, a polysiloxane containing a fluoroalkyl group can be used particularly preferably. Specifically, one or more hydrolyzed condensates of the following fluoroalkylsilanes, Examples include a hydrolytic condensate, and those generally known as a fluorine-based silane coupling agent may be used.

CF ₃ (CF ₂ ) ₃ CH ₂ CH ₂ Si (O
_{CH 3) 3 CF 3 (CF} 2) 5 CH 2 CH 2 Si (OCH 3) 3 CF 3 (CF 2) 7 CH 2 CH 2 Si (OCH 3) 3 CF 3 (CF 2) 9 CH 2 CH 2 Si (OCH ₃ ) ₃ (CF ₃ ) ₂ CF (CF ₂ ) ₄ CH ₂ CH ₂ Si (OC
_{H 3) 3 (CF 3)} 2 CF (CF 2) 6 CH 2 CH 2 Si (OC
_{H 3) 3 (CF 3)} 2 CF (CF 2) 8 CH 2 CH 2 Si (OC
_{H 3) 3 CF 3 (C} 6 H 4) C 2 H 4 Si (OCH 3) 3 CF 3 (CF 2) 3 (C 6 H 4) C 2 H 4 Si (OCH
₃ ) ₃ CF ₃ (CF ₂ ) ₅ (C ₆ H ₄ ) C ₂ H ₄ Si (OCH
₃ ) ₃ CF ₃ (CF ₂ ) ₇ (C ₆ H ₄ ) C ₂ H ₄ Si (OCH
₃ ) ₃ CF ₃ (CF ₂ ) ₃ CH ₂ CH ₂ SiCH ₃ (OC
H ₃ ) ₂ CF ₃ (CF ₂ ) ₅ CH ₂ CH ₂ SiCH ₃ (OC
H ₃ ) ₂ CF ₃ (CF ₂ ) ₇ CH ₂ CH ₂ SiCH ₃ (OC
H ₃ ) ₂ CF ₃ (CF ₂ ) ₉ CH ₂ CH ₂ SiCH ₃ (OC
_{H 3) 2 (CF 3)} 2 CF (CF 2) 4 CH 2 CH 2 SiCH 3
(OCH ₃ ) ₂ (CF ₃ ) ₂ CF (CF ₂ ) ₆ CH ₂ CH ₂ SiCH ₃
(OCH ₃ ) ₂ (CF ₃ ) ₂ CF (CF ₂ ) ₈ CH ₂ CH ₂ SiCH _{3
(OCH 3) 2 CF 3 (} C 6 H 4) C 2 H 4 SiCH 3 (OCH 3) 2 CF 3 (CF 2) 3 (C 6 H 4) C 2 H 4 SiCH
_{3 (OCH 3) 2 CF 3} (CF 2) 5 (C 6 H 4) C 2 H 4 SiCH
_{3 (OCH 3) 2 CF 3} (CF 2) 7 (C 6 H 4) C 2 H 4 SiCH
₃ (OCH ₃ ) ₂ CF ₃ (CF ₂ ) ₃ CH ₂ CH ₂ Si (OCH ₂ C
H ₃ ) ₃ CF ₃ (CF ₂ ) ₅ CH ₂ CH ₂ Si (OCH ₂ C
H ₃ ) ₃ CF ₃ (CF ₂ ) ₇ CH ₂ CH ₂ Si (OCH ₂ C
H ₃ ) ₃ CF ₃ (CF ₂ ) ₉ CH ₂ CH ₂ Si (OCH ₂ C
_{H 3) 3 CF 3 (CF} 2) 7 SO 2 N (C 2 H 5) C 2 H 4 CH
₂ Si (OCH ₃ ) ₃ By using a polysiloxane containing a fluoroalkyl group as described above as a binder, the water repellency and oil repellency of the non-light-irradiated portion of the photocatalyst containing layer are greatly improved.

The reactive silicone of the above (2) includes:
Compounds having a skeleton represented by the following general formula can be given.

-(Si (R ¹ ) (R ² ) O) _n-wherein n is an integer of 2 or more, and R ¹ and R ² are each a substituted or unsubstituted alkyl, alkenyl or aryl having 1 to 10 carbon atoms. Alternatively, it can be a cyanoalkyl group. Preferably, up to 40 mol% of the total can be vinyl, phenyl or phenyl halide. Also,
It is preferable that R ¹ and / or R ² be a methyl group because the surface energy is minimized. Preferably, the methyl group is at least 60 mol%, and at least one of the methyl group and the chain end or side chain in the molecular chain It has a reactive group such as the above hydroxyl group.

Further, a stable organosilicon compound which does not cause a cross-linking reaction, such as dimethylpolysiloxane, may be mixed with the binder together with the above-mentioned organopolysiloxane.

(Other Components Used in Photocatalyst-Containing Layer) The photocatalyst-containing layer used in the present invention may contain a surfactant in order to reduce the wettability of the unexposed portion. The surfactant is not limited as long as it can be decomposed and removed by a photocatalyst, and specifically, preferably, for example, NIKKOL BL, manufactured by Nippon Surfactant Industries, Ltd.
Hydrocarbon surfactants such as BC, BO and BB series, manufactured by DuPont: ZONYL FSN, FSO, manufactured by Asahi Glass: Surflon S-141, 145, manufactured by Dainippon Ink: Megafac F-141, 144, Neos: Futagent F-200, F251; Daikin Industries: Unidyne DS-401, 402; 3M: Florad FC-170, 176, etc., fluorine-based or silicone-based nonionic surfactants. In addition, cationic, anionic and amphoteric surfactants can also be used.

The photocatalyst-containing layer suitably used in the present invention contains other components such as polyvinyl alcohol,
Unsaturated polyester, acrylic resin, polyethylene, diallyl phthalate, ethylene propylene diene monomer, epoxy resin, phenol resin, polyurethane, melamine resin, polycarbonate, polyvinyl chloride, polyamide, polyimide, styrene butadiene rubber, chloroprene rubber, polypropylene, polybutylene, polystyrene And oligomers and polymers such as polyvinyl acetate, nylon, polyester, polybutadiene, polybenzimidazole, polyacrylonitrile, epichlorohydrin, polysulfide, and polyisoprene.

Further, the photocatalyst-containing layer used in the present invention may contain a sensitizing dye which is a component for sensitizing the photoactivity of the photocatalyst. By adding such a sensitizing dye, the wettability can be changed at a low exposure dose, or the wettability can be changed at a different wavelength. Further, an EL material can be added to the photocatalyst-containing layer. For example, by mixing a charge injecting material, a charge transporting material, or a light emitting material, the light emitting characteristics of the EL element can be improved.

(Ultraviolet absorber) An ultraviolet absorber can be used in the photocatalyst-containing layer used in the present invention. Such materials include BASF as a benzophenone-based material.
UVINUL D-49, UVINUL D manufactured by
-50, Chemisorb10 manufactured by Chemipro Kasei Co., Ltd.
11. Kemisorb 1001, MARK L manufactured by Adeka Argus Chemical Co., Ltd. as benzotriazole type
A-31, Sumisorb 25 manufactured by Sumitomo Chemical Co., Ltd.
0, aryl esters, oganilide, formamidine and the like.

(Method for Forming Photocatalyst-Containing Layer) The method for forming the photocatalyst-containing layer is not particularly limited. For example, a coating solution containing a photocatalyst is applied to a substrate by a method such as spray coating, dip coating, roll coating, or bead coating. It can be formed by coating.

When a coating solution containing a photocatalyst or the like is used, the solvent that can be used for the coating solution is not particularly limited, and examples thereof include alcoholic organic solvents such as ethanol and isopropanol.

(Irradiation Light for Activating Photocatalyst) Irradiation light for activating the photocatalyst is not limited as long as the photocatalyst can be excited. Examples of such a material include ultraviolet light, visible light, and infrared light, as well as electromagnetic waves and radiation having a shorter or longer wavelength than these light beams.

For example, when anatase titania is used as the photocatalyst, since the excitation wavelength is 380 nm or less, the photocatalyst can be excited by ultraviolet rays. As a device emitting such ultraviolet rays, a mercury lamp, a metal halide lamp, a xenon lamp, an excimer laser, and other ultraviolet light sources can be used.

EL Layer (Hole Transport Layer, Light Emitting Layer, and the Like) The EL layer provided in the EL element of the present invention has, as essential components, a hole transport layer that transports holes to the light emitting layer and a light emitting layer. Layer, as an optional layer, an electron transport layer for transporting electrons, and a hole injection layer for injecting holes into the light emitting layer or the hole transport layer and an electron injection layer for injecting electrons into the light emitting layer or the electron transport layer ( These may be collectively referred to as a charge injection layer).

The following are examples of materials constituting these EL layers.

(Light Emitting Layer) <Dye System> Cyclopentadiene derivative, tetraphenylbutadiene derivative, triphenylamine derivative, oxadiazole derivative, pyrazoloquinoline derivative, distyrylbenzene derivative, distyrylarylene derivative, silole derivative, thiophene ring Compound, pyridine ring compound,
Perinone derivative, perylene derivative, oligothiophene derivative, trifmanylamine derivative, oxadiazole dimer, virazoline dimer <metal complex> aluminum quinolinol complex, benzoquinolinol beryllium complex, benzoxazole zinc complex,
Benzothiazole zinc complex, azomethyl zinc complex, porphyrin zinc complex, eurobium complex, etc., have Al, Zn, Be or the like as a central metal or rare earth metals such as Tb, Eu, Dy, etc., and oxadiazole as a ligand Metal complexes having a thiadiazole, phenylpyridine, phenylbenzimidazole, quinoline structure or the like.

<Polymer System> Polyparaphenylene vinylene derivative, polythiophene derivative, polyparaphenylene derivative, polysilane derivative, polyacetylene derivative, polyvinylcarbazole, etc., polyfluorene derivative (doping material) perylene derivative, coumarin derivative,
Rubrene derivative, quinacridone derivative, squarium derivative, porphyrin derivative, styryl dye, tetracene derivative, pyrazoline derivative, decacyclene, phenoxazone (hole transport layer) In the EL device of the present invention, the hole transport layer comprises a first electrode and a photocatalyst containing layer. And provided between them. Materials used for the hole transport layer include, for example, triphenylamines, bis, pyrazoline derivatives, stilbene compounds, oxadiazole derivatives, phthalocyanine derivatives, heterocyclic compounds represented by porphyrin derivatives, and the above-described single compounds in polymer systems. Examples thereof include a polycarbonate having a monomer in a side chain, a styrene derivative, polyvinyl carbazole, polythiophene, and polysilane.

(Electron Transport Layer) In the EL device of the present invention, the electron transport layer can be provided between the light emitting layer and the second electrode. Examples of the material used for the electron transporting layer include substances that generally form stable radical anions and have a large ionization potential, such as oxadiazoles and aluminum quinolinol complexes.
Examples thereof include 1,3,4-oxadiazole derivatives and 1,2,4-triazole derivatives.

(Hole Injection Layer (Anode Buffer Material)) In the EL device of the present invention, the hole injection layer can be provided between the first electrode and the hole transport layer. The materials used for the hole injection layer include the following. Oxides such as phenylamine, starburst amine, phthalocyanine, vanadium oxide, molybdenum oxide, ruthenium oxide, and aluminum oxide, amorphous carbon, polyaniline, and polythiophene derivatives (electron injection layer (cathode buffer material)) EL of the present invention In the device, the electron injection layer can be provided between the electron transport layer and the second electrode. The materials used for the electron injection layer include the following. Aluminum lithium, lithium fluoride, strontium, magnesium oxide, magnesium fluoride, strontium fluoride, calcium fluoride, barium fluoride, aluminum oxide, strontium oxide, calcium, polymethyl methacrylate,
Sodium polystyrenesulfonate (partition layer material in EL layer) A partition may be provided in the EL layer, and the partition is particularly useful when combining EL layers emitting different colors. Examples of such a material include a photosensitive polyimide resin, an acrylic resin, a photocurable resin, a thermosetting resin, and a water-repellent resin.

First Electrode and Second Electrode In this specification, the electrode provided first on the substrate is referred to as the first electrode, and the electrode provided thereafter on the EL layer is referred to as the second electrode. The first electrode is transparent or translucent. Although these electrodes are not particularly limited, preferably, the electrodes include an anode and a cathode, and in this case, the first electrode may be either an anode or a cathode. The anode is preferably a conductive material having a large work function so that holes can be easily injected, and the cathode is preferably a conductive material having a small work function so that electrons can be easily injected. Further, a plurality of materials may be mixed. The resistance of each electrode is preferably as low as possible. In general, a metal material is used, but an organic substance or an inorganic compound may be used.

Specifically, preferred anode materials are ITO,
Examples of indium oxide, gold, polyaniline, and cathode materials include magnesium alloys (eg, MgAg), aluminum alloys (eg, AlLi, AlCa, AlMg), and calcium metal.

Substrate In the present invention, the substrate is a substrate on which electrodes and an EL layer are provided, and can be made of a transparent material if desired, but may be an opaque material. In the EL device of the present invention, the substrate may be the first electrode itself, but usually the first electrode is provided directly or via an intermediate layer on the surface of the substrate that maintains strength.

Refractive Index Changing Material Layer In the EL device of the present invention, at least one refractive index changing material layer by light irradiation can be provided at any position between the substrate and the photocatalyst containing layer.

The material layer whose refractive index can be changed by light irradiation used in the EL device of the present invention includes a material whose refractive index can be changed by light exposure and / or a material whose light refractive index has changed (including a material which has been subjected to a fixing treatment after the change). ) Is not limited.

(Effect of Refractive Index Changing Material Layer) Light is radiated in all directions from the light emitting layer of the EL element. Among them, the light that is effectively visually recognized as display light is transmitted from the light emitting layer to the display surface of the EL element. Only a part of the light emitted to the light-emitting region, and the others leak to the non-light-emitting region. Further, even when the light is radiated toward the display surface, the radiated light having a small angle with respect to the display surface may not contribute much to the visibility of the display. The refractive index changing material layer radiated from the light emitting layer by total reflection of EL light generated at the interface between the portion where the refractive index was changed by the light irradiation and the portion where the refractive index did not change (in some cases, a refraction effect was added). The layer can reduce the escape of light in the horizontal direction, increase the component in the normal direction of the display surface, increase the intensity of EL display light, and improve visibility.

FIG. 1 is a diagram schematically illustrating a cross section of an EL element having such a refractive index changing material layer. In this EL device, a refractive index changing material layers 2 and 3, a first electrode 4, a hole transport layer 5, a photocatalyst containing layer 6, a light emitting layer 7, and a second electrode 8 are sequentially provided on a base 1. The portion indicated by reference numeral 2 in the refractive index changing material layer is a portion whose refractive index has been increased by light irradiation, and the portion indicated by reference numeral 3 is a low refractive index portion not irradiated with light. Light-emitting layer 7 of EL device of the present invention
Some of the light emitted from the light source a and b directly reach the light-emitting region, such as light beams a and b. However, even if the light beam c does not reach the light-emitting region in the past, the refractive index changing material layers 2 and 3 The light reaches the EL element light emitting region by being reflected at the interface with the light emitting element, and is emitted as light that can be visually recognized effectively. Further, in the case of full-color display, a light ray c that reaches a light emitting region of an adjacent color to cause color mixing and disturbs the color is reflected at the interface between the refractive index changing material layer 2 and the refractive index changing material layer 3 so as to be adjacent. And the contrast, the viewing angle, and the visibility are improved.

As described above, due to the difference in the refractive index between the refractive index changing material layer in the light emitting region of the EL element and the refractive index changing material layer in the non-light emitting region, light leaked to the non-light emitting region of the EL element is emitted. The light is reflected by the light emitting region, and the luminance of the EL element is improved. The ratio of the reflected light increases as the difference in the refractive index increases, and increases as the incident angle X increases. Therefore, the refractive index changing material layer 2
It is more preferable that the difference between the refractive indices and is larger. Further, forming the interface between the refractive index changing material layers 2 and 3 obliquely so as to spread in the direction of the display surface as shown in FIG. 1 increases light rays having a large incident angle X and increases reflected light. It is preferred. Also, preferably, the refractive index of the material forming the base 1, the refractive index changing material layer 2, the first electrode 4, the hole transport layer 5, the photocatalyst containing layer 6, and the light emitting layer 7 is made close to each other, and the reflection at the interface between them is obtained. Is preferably prevented. Further, increasing the thickness of the refractive index changing material layer 2 as compared with the thickness of the first electrode 4, the hole transport layer 5, and the photocatalyst containing layer 6 increases the ratio of the light directed toward the non-light emitting region to the light emitting region by reflection. It can be increased and is preferable.

(Shape and Arrangement of Refractive Index Changing Material Layer) In the EL device of the present invention, the interface between the refractive index changing material layers having different refractive indices may be perpendicular to the display surface.
It is preferable to irradiate the light for changing the refractive index at an angle so that the interface spreads from the light emitting layer toward the display surface as described above. By doing so, the amount of reflected light increases, so that the light extraction efficiency can be further improved and light leakage can be reduced.

In the EL device of the present invention, the refractive index changing material layer is provided outside the first electrode, between the first electrode and the hole transport layer, between the hole transport layer and the EL layer, and when there are a plurality of EL layers. Layers, between the EL layers, between the EL layer and the second electrode,
When the base is provided outside the second electrode, outside the first or second electrode, it can be provided at any position such as the base or outside the base. Preferably, the light emitting layer constituting the EL layer and the transparent electrode (the first electrode and / or the second electrode)
The optical action of the present invention can be efficiently obtained by providing a refractive index changing material layer between the electrode and the transparent electrode or at any position outside the transparent electrode. In addition, it is preferable to provide the refractive index changing material layer outside the electrode because there is no restriction on the electrical characteristics of the material of the refractive index changing material layer and a wide range of materials can be selected.

(Refractive index changing material) A refractive index changing material having a large change in refractive index before and after light irradiation is preferable because the amount of reflected light is large. In particular, in a full-color EL element, as this ratio increases, color bleeding due to leakage of light of adjacent different colors can be reduced.

The refractive index changing material can be fixed in a refractive index pattern by a method such as heat treatment such as baking in an oven, or heat treatment after irradiation with ultraviolet rays, and the refractive index changes even after light irradiation. It is preferable that the material is not used.

Although such a refractive index changing material is not particularly limited, for example, a material conventionally known as a photopolymer for hologram recording can be used. The hologram recording photopolymer contains a monomer, a photopolymerization initiator / sensitizer, and a binder as main components. Examples of these materials include the following.

The monomers include photopolymerizable, photocrosslinkable monomers, oligomers, prepolymers and mixtures thereof having at least one ethylenically unsaturated double bond in one molecule, and monomers and copolymers thereof. Examples thereof include unsaturated carboxylic acids and salts thereof, esters of unsaturated carboxylic acids and aliphatic polyhydric alcohol compounds, and amides of unsaturated carboxylic acids and aliphatic polyamine compounds.

Examples of the photopolymerization initiator and sensitizer include general ones.

Examples of the binder include polymethacrylate or its partial hydrolyzate, polyvinyl acetate or its hydrolyzate, polystyrene, polyvinyl butyral, polychloroprene, polyvinyl chloride, chlorinated polyethylene, chlorinated polypropylene, -N-vinylcarbazole or a derivative thereof, poly-N-vinylpyrrolidone or a derivative thereof, a copolymer of styrene and maleic anhydride or a half ester thereof, acrylic acid, acrylic ester, methacrylic acid, methacrylic ester,
A copolymer containing a monomer selected from a group of copolymerizable monomers such as acrylamide and acrylonitrile as a polymerization component can be used.

(Irradiation light beam for changing the refractive index) The irradiation light beam for changing the refractive index is not particularly limited as long as the refractive index of the material can be changed. Can also be short or long wavelength electromagnetic waves, radiation.

The EL element of the present invention can be a combination of the above-mentioned material that changes the refractive index by irradiation with light and the photocatalyst material in the photocatalyst containing layer that can react with light of the same wavelength. Such a combination is preferable because the irradiation of light for changing the refractive index of the refractive index changing material layer can also change the wettability of the photocatalyst-containing layer, which leads to simplification of the process and the like.

On the other hand, the EL device of the present invention may be a combination of a material in which the refractive index changing material by light irradiation and a photocatalyst material in a photocatalyst containing layer described later do not react with light of the same wavelength. With such a combination, the refractive index can be changed within a desired range without relating the change in the refractive index and the change in the wettability of the photocatalyst-containing layer.

(Method of Forming Refractive Index Changing Material Layer) The method of forming the refractive index changing material layer is not particularly limited. For example, a coating solution containing the refractive index changing material is spray-coated, dip-coated, roll-coated, and bead-coated. , Spin coating, gravure coating, blade coating, die coating and the like.

When a coating solution containing a refractive index changing material or the like is used, the solvent that can be used for the coating solution is not particularly limited. For example, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, benzene, toluene, xylene Chlorobenzene, tetrahydrofuran, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, ethyl acetate, 1,4-dioxane, 1,2-dichloroethane, dichloromethane, chloroform, methanol, ethanol, isopropanol and the like. .

Photodegradable Dye-Containing Layer by Light Irradiation In the EL device of the present invention, the hole transporting layer and / or the photocatalyst-containing layer may be a photodegradable dye-containing layer containing a dye that is decomposed by light irradiation. .

The photo-decomposable dye-containing layer used in the EL device of the present invention is a dye which is capable of decomposing a dye material upon exposure to light, thereby deteriorating the color of the dye, typically fading, and preferably becoming colorless. The layer is not limited as long as it is a layer containing a changed dye (including a dye subjected to an immobilization treatment after the change).

When a photodegradable dye is added to the photocatalyst-containing layer, if pattern exposure is performed with light that can cause both the photocatalyst and the photodecomposable dye to react, the wettability-improved portion and the dye-decomposed portion due to the photocatalytic reaction become one. Therefore, for example, it is preferable in that an EL element in which the light emitting layer formed on the wettability improving portion and the transparent portion formed by photolysis coincide can be easily manufactured.

(Function of Photodegradable Dye-Containing Layer) In the present invention, the photodegradable dye-containing layer is provided with a function as a light-shielding layer, that is, it blocks only a black matrix or light of a specific wavelength. be able to. Such a light-shielding layer can be easily formed by, for example, irradiating light other than the light-shielding portion of the photodegradable dye-containing layer (a portion corresponding to the EL element light-emitting region) to decompose the light-emitting layer. Color mixture with light of a different color from the surface and bleeding can be prevented.

In the present invention, the photodegradable dye-containing layer after light irradiation has a function as an alignment mark.
It can be an alignment mark that may be required when forming by a method such as electric field jet or mask evaporation. Such alignment marks can be visually inspected or CCD
It can be easily identified by such monitors. If necessary, light can be irradiated again in a later step to erase the data.

(Photodecomposable Dye) The photodecomposable dye which can be used in the present invention can decompose the dye material upon exposure to light, whereby the color of the dye is decomposed, typically fade, and can preferably be colorless. The dye is not limited as long as it is a dye and / or a changed dye (including those subjected to an immobilization treatment after the change).

The color of the dye can be arbitrarily selected according to the purpose of coloring. For example, when an alignment mark is formed using a photodegradable dye, the alignment mark is preferably black, the exposed portion is colorless, and the contrast can be high.

In the case where the light-shielding layer is formed using a photodegradable dye, the color can be a color that absorbs the emission color of the light-emitting layer in addition to black.

Such photodegradable dyes include, for example, disubstituted and monosubstituted paraphenylenediamines, aminohydroquinone ether derivatives, aminodiphenyl, aminodiphenylamines, heterocyclic amines, specifically,
(4-diazo-N, N-dimethylaniline), (4-diazo-N, N-diethylaniline), (4-diazo-N-ethyl-N-β-hydroxyethylaniline), (4-diazo-2,5 -Diethoxybenzoylaniline derivative)
Is mentioned.

The photodegradable dye is preferably heat-treated,
It is preferable to use one that does not decompose the pigment by an oven at 100 to 150 ° C. or hot plate drying. As such a dye, if it is red, rhodamine 6G
Is mentioned. (Method of forming photodegradable dye-containing layer) The method of forming the photodegradable dye-containing layer is not particularly limited. For example, a coating solution containing a photodegradable dye is spray-coated, dip-coated,
It can be formed by applying by a method such as roll coating, bead coating, spin coating, gravure coating, blade coating, and die coating.

When a coating solution containing a photodecomposable dye or the like is used, the solvent that can be used for the coating solution is not particularly limited, but for example, the solvent that can be used for the coating solution is not particularly limited. But, for example, acetone,
Methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, benzene, toluene, xylene, chlorobenzene, tetrahydrofuran, methyl cellosolve, ethyl cellosolve, methyl cellosolve acetate, ethyl cellosolve acetate, ethyl acetate, 1,4-dioxane, 1,2-dichloroethane, dichloromethane, Chloroform, methanol, ethanol, isopropanol and the like can be mentioned.

Since photodegradable dyes are often degraded by heat, when heat drying is used in the process of forming a photodegradable dye-containing layer, drying is carried out with heat to such an extent that the dye does not deteriorate depending on the dye.

(Irradiation Light for Decomposing Dye) In the present invention, the irradiation light for decomposing the dye is not particularly limited as long as the photodegradable dye can be decomposed. Such materials include ultraviolet (UV), visible light, and infrared light, as well as electromagnetic waves and radiation having a shorter or longer wavelength than these light beams. In addition, the reaction wavelength band of the photocatalyst-containing layer and the reaction wavelength band of the photodegradable dye-containing layer at least partially overlap with each other. It is preferable to react both the photodecomposable dye-containing layer and the photodecomposable dye-containing layer. Further, it is preferable to use a photodegradable dye and a photocatalyst that do not cause the irradiation light to react with another EL layer, for example, a hole transport layer, in other words, that react with light that does not decompose the EL layer.

Manufacturing Method The method for manufacturing an EL element of the present invention comprises the steps of: forming at least the first electrode on the base;
A step of forming a hole transport layer, a step of forming a photocatalyst-containing layer on the hole transport layer, and a step of exposing the photocatalyst-containing layer in a pattern to form a pattern due to a difference in wettability. A step of forming a patterned light emitting layer by applying a light emitting layer forming liquid on an exposed portion of the photocatalyst containing layer; and forming the second electrode on the light emitting layer. Is the way.

Further, the layer provided in the preferred embodiment of the present invention can be formed by a usual method for manufacturing an EL device.

Solvent of Coating Solution The luminescent layer forming solution applied to form the luminescent layer on the photocatalyst containing layer (these are called coating solutions) is preferably a solvent such as a polar solvent such as water. A coating solution using such a polar solvent has high wettability with the exposed portion of the photocatalyst-containing layer and has a strong tendency to repel the unexposed portion, which is advantageous in patterning the coating solution.

Coating Method Application of the coating solution to the photocatalyst-containing layer includes spin coating, ink jetting, dip coating, blade coating, and dropping to the photocatalyst-containing layer.

Patterning Method The light emitting layer formed on the photocatalyst containing layer is patterned
In addition to the method of patterning in the state of the coating liquid before solidification,
It is also possible to peel off only a portion having low wettability in a state where a layer after solidification is formed. Specifically, for example, a method of sticking an adhesive tape after solidification and peeling it off may be used.

[0078] Wettability pattern and pixel EL element of the present invention, in the case of display of full color display, preferably, in correspondence to the pattern by wettability differences between the photocatalyst-containing layer to form a pixel of the display.

[0079]

EXAMPLE 1 3 parts by weight of isopropyl alcohol and 2 parts by weight of anatase titania sol were mixed, stirred at 90 ° C. for 10 minutes, and further mixed with 0.14 parts by weight of fluoroalkoxylan.
After stirring at 90 ° C. for 10 minutes, the solution 1 was diluted 4 times with isopropyl alcohol to obtain a solution 2.

A cleaning treatment and a surface treatment are performed on the patterned ITO glass substrate (the work function after the cleaning process is 5.0 eV), and a substrate A on which a solution 2 is applied by a spin coater and a PEDOT (hole) 4. transport layer, work function
Substrates B coated with 2 eV) were prepared. The drying conditions were each left on a hot plate at 150 ° C. for 10 minutes. In both cases, a thin film of 20 to 100 nm was obtained by controlling the rotation speed of spin coating. Next, PED
Solution 2 is applied on the OT layer by spin coating,
Drying was performed for 10 minutes.

Next, an opening mask was prepared, and a mercury lamp (having a main wavelength of 365 nm) was formed on the photocatalyst containing layers of both substrates in an opening pattern.
m, 30 mW / cm ² ) for 10 minutes. The work function of the photocatalyst-containing layer before irradiation with a mercury lamp was 4.8 eV, 1
After irradiation for 0 minutes, it was 5.3 eV.

Further, a light-emitting layer forming solution described later is applied on both substrates by spin coating, dried in a dry box at 90 ° C. for 1 hour, and a thin film of a light-emitting layer (work function: 5.7 eV) of about 80 nm is formed. It was formed on a pattern. Finally, C is used as an electron injection layer so as to be orthogonal to the pattern of ITO.
a is 200 angstroms, and Ag is 200 as an electrode.
0 Å was deposited by mask to obtain an EL device.

Emitting Layer Forming Solution Polyvinylcarbazole 7 parts by weight Luminescent dye (R, G or B) 0.1 part by weight Oxadiazole compound 3 parts by weight Toluene 5050 parts by weight Luminescent dye G is coumarin 6 and luminescent dye R is Nile Red ,
As the luminescent dye B, a perylene compound was used.

The EL element A manufactured using the substrate A and the EL element B manufactured using the substrate B were each connected to an ITO electrode,
When the light emission characteristics were measured by driving the upper Ag electrode as an address electrode, the EL element B had a lower light emission start voltage and higher luminance than the EL element A.

[0085]

According to the present invention, it is possible to provide an EL element which can be easily manufactured and a method for manufacturing the same.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of the EL device of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Base | substrate 2 Refractive-index change material layer (part which changed refractive index) 3 Refractive-index change material layer (part which does not change refractive index) 4 1st electrode 5 Hole transport layer 6 Photocatalyst containing layer 7 Light emitting layer 8 2nd electrode

Claims (16)

[Claims] 1. A base, a transparent first electrode formed on the base, a hole transport layer formed on the first electrode,
An EL device comprising at least a photocatalyst containing layer formed on the hole transport layer, a light emitting layer formed on the photocatalyst containing layer, and a second electrode formed on the light emitting layer. . 2. The EL device according to claim 1, further comprising an electron transport layer between said light emitting layer and said second electrode. 3. The EL device according to claim 1, further comprising a hole injection layer between said first electrode and said hole transport layer. 4. The EL device according to claim 2, further comprising an electron injection layer between said electron transport layer and said second electrode. 5. The photoconductor according to claim 1, wherein the hole transport layer has a work function larger than ITO and smaller than the photocatalyst containing layer.
3. The EL device according to claim 1. 6. The E according to claim 1, wherein the work function of the photocatalyst-containing layer changes according to the amount of light to be irradiated.
L element. 7. The EL device according to claim 1, wherein at least one layer of a refractive index changing material layer by light irradiation is provided at any position between the substrate and the photocatalyst containing layer. 8. The EL device according to claim 1, wherein said hole transport layer and / or said photocatalyst containing layer contains a photodegradable dye. 9. The EL device according to claim 1, further comprising a photodegradable dye-containing layer between said base and said first electrode. 10. The EL device according to claim 1, wherein the photocatalyst-containing layer contains an ultraviolet absorbing material. 11. The photocatalyst-containing layer has a thickness of 50 to 200.
2. The EL device according to claim 1, wherein 0 °. 12. A full-color display using the EL element according to claim 1. 13. A substrate, a transparent first electrode formed on the substrate, a hole transport layer formed on the first electrode, and a photocatalyst containing layer formed on the hole transport layer. And a light emitting layer formed on the photocatalyst containing layer, and a second electrode formed on the light emitting layer, the method for manufacturing an EL element, wherein the step of forming the first electrode on the substrate Forming a hole transport layer on the first electrode; forming a photocatalyst-containing layer on the hole transport layer; exposing the photocatalyst-containing layer in a pattern to obtain a wettability. A step of forming a pattern according to the difference, a step of applying a light emitting layer forming liquid on the exposed portion of the photocatalyst containing layer to form the patterned light emitting layer, and forming the second electrode on the light emitting layer A method of manufacturing an EL element. 14. The method according to claim 13, further comprising the step of adjusting the amount of light applied to the photocatalyst-containing layer to change the work function of the photocatalyst-containing layer. 15. The display according to claim 15, wherein the EL element is a full-color display, and emits red (R), green (G), and blue (B) light corresponding to a pattern due to a difference in wettability of the photocatalyst-containing layer. 14. The method according to claim 13, wherein the layers are formed at locations corresponding to the pixels R, G, B of the display. 16. A method for changing the work function of a photocatalyst-containing layer by adjusting the amount of light applied to the photocatalyst-containing layer in manufacturing the EL device according to claim 1.