JP2010276829A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display device which is high in the aperture ratio of an organic EL element and can highly efficiently taking out light rays emitted from the organic EL element. <P>SOLUTION: The display device includes: a drive substrate 21 with light permeability in which the drive substrate with light permeability is formed; a plurality of organic electroluminescence (EL) elements 31 provided on the drive substrate 21 which emit light to the drive substrate 21 by being driven by the drive circuit; and a film 41 which is arranged under the plurality of organic EL elements 31 by inserting the drive substrate 21 between them. The organic EL element 31 is arranged at a position overlapping with the drive circuit viewing from a thickness direction of the drive circuit 21. In the film 41, a haze value is 70% or larger, and total light permeability is 50% or higher. A surface which is opposite to a drive substrate side has an irregular shape, and the surface of the irregular shape has an interface with an atmosphere. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a display device.

  An organic electroluminescence element (hereinafter, “electroluminescence” is sometimes referred to as “EL”) is a kind of light emitting element, and is opposed to a light emitting layer using an organic substance as a light emitting material with the light emitting layer interposed therebetween. And a pair of electrodes (anode and cathode) arranged. When a voltage is applied to the organic EL element, holes are injected from the anode and electrons are injected from the cathode, and light is emitted by combining these holes and electrons in the light emitting layer.

  The organic EL element is used as a pixel light source of a display device, for example. Display devices are roughly classified into an active matrix (AM) driving method and a passive matrix (PM) driving method depending on the driving method. For example, in an AM driving type display device, a plurality of organic EL elements are provided on a driving substrate on which driving circuits for individually driving the organic EL elements are formed. Each organic EL element functions as a pixel light source by being individually driven by this drive circuit.

  In the drive circuit formed on the drive substrate, a thin film transistor (TFT) is generally used as a switching element. Currently, various researches and developments have been made for the purpose of improving various characteristics of the thin film transistor. For example, a transparent thin film transistor using an amorphous oxide semiconductor as a semiconductor has been proposed (see, for example, Non-Patent Document 1).

Toshio Kamiya et al., “Design of amorphous oxide semiconductors and room-temperature formation of high-performance flexible thin-film transistors”, 19th Advanced Technology Award Paper, [online], [Search April 9, 2008], Internet <URL: http : //www.fbi-award.jp/sentan/jusyou/2005/toko_canon.pdf>

  As a configuration of the display device, there are a form in which light emitted from the organic EL element passes through the driving substrate and is visually recognized by the viewer, and a form in which the light is directly viewed by the viewer without passing through the driving substrate. That is, there are a form in which the driving substrate is interposed between the viewer and the organic EL element, and a form in which the organic EL element is arranged closer to the viewer than the driving substrate. In the former, the organic EL element is mounted on the driving substrate so as to emit light toward the driving substrate, and in the latter, the organic EL element is mounted on the driving substrate so as to emit light on the side opposite to the driving substrate. The organic EL element that emits light to the opposite side of the drive substrate (sometimes called "top emission type") does not block the light by the drive circuit, so the aperture ratio is limited for the drive circuit. Will never be done. However, in an organic EL element configured to emit light to the drive substrate side (sometimes referred to as a “bottom emission type”), light is blocked by the drive circuit, and thus the aperture ratio is inevitably limited due to the drive circuit. .

  In the bottom emission type organic EL element, the aperture ratio is limited by the drive circuit. As a result, the area of the light emitting surface of the organic EL element (hereinafter sometimes referred to as a light emission area) is limited. Therefore, when the luminance is set to a predetermined value, the intensity of light emitted from the entire element is lowered. Even if the aperture ratio is limited in this way, it is possible to increase the luminance by increasing the voltage applied to the organic EL element. Therefore, if the intensity of light emitted from the entire element is increased, It is possible to control the emitted light to the desired intensity. However, in this case, the load on the organic EL element is increased, which causes a problem that the element life is shortened. Therefore, a higher aperture ratio is preferable. Since the above-mentioned thin film transistor is transparent, the aperture ratio is certainly improved by using it for the TFT substrate. However, in order to improve the characteristics of the device, further improvement of the aperture ratio is required.

  Further, the light emitted from the organic EL element is reflected by total reflection or the like at the interface between the driving substrate and the outside air, so that most of the light is confined inside the apparatus without being emitted to the outside. Therefore, at present, most of the light emitted from the organic EL element is not effectively used. As described above, even if part of the light is reflected, it is possible to control the light emitted through the TFT substrate to the desired intensity by increasing the voltage applied to the organic EL element. In this case, there arises a problem that the element life is shortened. Therefore, there is a demand for an apparatus configured to emit light emitted from an organic EL element to the outside with higher efficiency.

  Accordingly, an object of the present invention is to provide a display device in which the aperture ratio of an organic EL element is high and light emitted from the organic EL element can be extracted with high efficiency.

The present invention includes a drive substrate exhibiting light transparency on which a drive circuit exhibiting light transparency is formed,
A plurality of organic electroluminescence elements that are provided on the driving substrate and are driven by the driving circuit to emit light toward the driving substrate;
A film disposed with the drive substrate interposed between the plurality of organic electroluminescence elements, and a display device having
The organic electroluminescence element is disposed at a position overlapping the drive circuit as viewed from one of the thickness directions of the drive substrate,
The film has a haze value of 70% or more and a total light transmittance of 50% or more, the surface opposite to the driving substrate side is uneven, and the uneven surface forms an interface with the atmosphere. The present invention relates to a display device.

  According to the present invention, the driving circuit includes a light-transmitting wiring disposed at a position overlapping the organic electroluminescence element when viewed from one side in the thickness direction of the driving substrate, and the wiring is an inorganic oxide conductor. It is related with the said display apparatus characterized by comprising.

  The drive circuit includes a transistor element exhibiting light transmittance disposed at a position overlapping the organic electroluminescence element when viewed from one side in the thickness direction of the drive substrate, and the transistor element is an inorganic oxide. The display device includes a semiconductor layer made of a semiconductor.

Further, in the present invention, the inorganic oxide semiconductor and the inorganic oxide conductor are zinc tin oxide or indium-containing oxide, respectively.
The semiconductor layer has a carrier concentration lower than that of the wiring.

  The present invention also relates to the display device, wherein the film is provided with a plurality of concave surfaces on the surface opposite to the drive substrate side, and the surfaces are formed in an uneven shape.

  A display device in which the aperture ratio of the organic EL element is high and light emitted from the organic EL element can be extracted with high efficiency can be realized.

FIG. 1 is a plan view showing a part of the display device 1 of the present embodiment. FIG. 2 is an enlarged sectional view showing a region corresponding to one pixel in the display device. FIG. 3 is a diagram showing a part of the circuit configuration of the drive circuit. FIG. 4 is a view schematically showing a cross section of the film A produced in Production Example 1. FIG. 5 is a view schematically showing a cross section of the film B used in Production Example 2. FIG. 6 is a view schematically showing a cross section of the film C produced in Comparative Example 1.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a plan view showing a part of the display device 1 of the present embodiment. FIG. 2 is an enlarged sectional view showing a region corresponding to one pixel in the display device. FIG. 3 is a diagram showing a part of the circuit configuration of the drive circuit.

  The display device 1 includes a light-transmissive drive substrate 21 on which a light-transmissive drive circuit 11 is formed, and is provided on the drive substrate, and is driven by the drive circuit 11 to emit light toward the drive substrate. A plurality of organic EL elements 31 that emit light, and a film 41 that is disposed with the drive substrate 21 interposed between the plurality of organic EL elements 31. In this specification, “light” means light in the wavelength range emitted by the organic EL element, and usually means visible light. Therefore, that the predetermined member exhibits light transmittance means that at least a part of the light emitted from the organic EL element and incident on the predetermined member is transmitted.

(1) Configuration of Display Device First, the configuration of the display device 1 will be described.

(Organic EL device)
The organic EL element 31 is provided on the drive substrate 21 and is driven by the drive circuit 11 to emit light toward the drive substrate 21. In other words, a plurality of bottom emission type organic EL elements 31 are provided on the drive substrate 21. In the present embodiment, a plurality of organic EL elements 31 are provided in a matrix on the drive substrate 21. Specifically, the plurality of organic EL elements 31 are arranged on the drive substrate 21 at equal intervals in the row direction X and at discrete intervals in the column direction Y.

  A grid-like partition wall 51 extending in the row direction X and the column direction Y is provided on the drive substrate 21. The partition wall 51 is provided to separate the organic EL elements 31. Each organic EL element 31 is provided in a region surrounded by the lattice-shaped partition walls 51. In other words, the partition walls 51 are arranged so as to be interposed between the organic EL elements 31 adjacent in the row direction X and the column direction Y.

  The organic EL element 31 includes a pair of electrodes 32 and 33 and one or more predetermined layers 34 disposed between the electrodes. On one surface of the drive substrate 21 in the thickness direction, one of a pair of electrodes (hereinafter, “one electrode” is referred to as “first electrode 32”, and “the other electrode” is referred to as “second electrode”. 33 ").) Is provided. One of the first electrode 32 and the second electrode 33 is provided as an anode, and the other is provided as a cathode. In the following description, one of the drive substrate 21 in the thickness direction may be referred to as “upper” or “upper”, and the other in the thickness direction may be referred to as “lower” or “lower”.

  One first electrode 32 is provided for one organic EL element 31. That is, the same number of first electrodes 32 as the organic EL elements 31 are formed on the drive substrate 21. The plurality of first electrodes 32 are provided in a matrix on the drive substrate 21. That is, the first electrodes 32 are discretely arranged on the drive substrate 21 at regular intervals in the row direction X and at regular intervals in the column direction Y. The first electrode 32 has a flat plate shape, and is formed in a substantially rectangular shape when viewed from one side in the thickness direction of the drive substrate 21 (hereinafter sometimes referred to as “in plan view”). The first electrode 32 is provided in a region surrounded by the partition wall 51 in a plan view, and a peripheral portion thereof overlaps a part of the partition wall 51. Since the organic EL element 31 emits light through the first electrode 32, the first electrode 32 is composed of a conductive thin film exhibiting light transmittance.

  The organic EL element 31 includes at least one light emitting layer as the predetermined layer 34. The predetermined layer 34 is disposed in a region overlapping the first electrode 32 in a plan view, that is, a region surrounded by the partition wall 51.

  Examples of the layer provided between the cathode and the light emitting layer include an electron injection layer, an electron transport layer, and a hole blocking layer. In the case where both the electron injection layer and the electron transport layer are provided between the cathode and the light emitting layer, the layer in contact with the cathode is referred to as an electron injection layer, and the layer excluding this electron injection layer is referred to as an electron transport layer.

  The electron injection layer has a function of improving electron injection efficiency from the cathode. The electron transport layer has a function of improving electron injection from the cathode, the electron injection layer, or the electron transport layer closer to the cathode. The hole blocking layer has a function of blocking hole transport. In the case where the electron injection layer and / or the electron transport layer have a function of blocking hole transport, these layers may also serve as the hole blocking layer.

  Examples of the layer provided between the anode and the light emitting layer include a hole injection layer, a hole transport layer, and an electron block layer. When both the hole injection layer and the hole transport layer are provided between the anode and the light-emitting layer, the layer in contact with the anode is called a hole injection layer, and the layers other than the hole injection layer are positive. It is called a hole transport layer.

  The hole injection layer has a function of improving hole injection efficiency from the anode. The hole transport layer has a function of improving hole injection from the anode, the hole injection layer, or the hole transport layer closer to the anode. The electron blocking layer has a function of blocking electron transport. In the case where the hole injection layer and / or the hole transport layer has a function of blocking electron transport, these layers may also serve as an electron blocking layer.

  The electron injection layer and the hole injection layer may be collectively referred to as a charge injection layer, and the electron transport layer and the hole transport layer may be collectively referred to as a charge transport layer.

  In the present embodiment, the second electrode 33 is formed over the entire surface of the drive substrate 21 from the predetermined layer 34 and is provided as an electrode common to each organic EL element 31.

An example of a layer structure that can be taken by the organic EL element of the present embodiment is shown below.
a) anode / light emitting layer / cathode b) anode / hole injection layer / light emitting layer / cathode c) anode / hole injection layer / light emitting layer / electron injection layer / cathode d) anode / hole injection layer / light emitting layer / Electron transport layer / cathode e) anode / hole injection layer / light emitting layer / electron transport layer / electron injection layer / cathode f) anode / hole transport layer / light emitting layer / cathode g) anode / hole transport layer / light emitting layer / Electron injection layer / cathode h) anode / hole transport layer / light emitting layer / electron transport layer / cathode i) anode / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode j) anode / hole Injection layer / hole transport layer / light emitting layer / cathode k) anode / hole injection layer / hole transport layer / light emitting layer / electron injection layer / cathode l) anode / hole injection layer / hole transport layer / light emitting layer / Electron transport layer / cathode m) anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode n) anode / light emitting layer / electron injection layer / cathode o) anode / Photo layer / electron transport layer / cathode p) anode / light emitting layer / electron transport layer / electron injection layer / cathode (here, the symbol “/” indicates that the layers sandwiching the symbol “/” are stacked adjacent to each other) The same shall apply hereinafter.)
The organic EL element of the present embodiment may have two or more light emitting layers. In any one of the layer configurations of a) to p) above, when the laminate sandwiched between the anode and the cathode is referred to as “structural unit A”, the configuration of the organic EL element having two light emitting layers is obtained. Examples of the layer structure shown in the following q) can be given. Note that the two (structural unit A) layer structures may be the same or different.
q) Anode / (structural unit A) / charge generating layer / (structural unit A) / cathode If “(structural unit A) / charge generating layer” is “structural unit B”, it has three or more light emitting layers. Examples of the structure of the organic EL element include the layer structure shown in the following r).
r) anode / (structural unit B) x / (structural unit A) / cathode The symbol “x” represents an integer of 2 or more, and (structural unit B) x is a stack in which “structural unit B” is stacked in x stages. Represents the body. A plurality of (structural units B) may have the same or different layer structure.

  Here, the charge generation layer is a layer that generates holes and electrons by applying an electric field. Examples of the charge generation layer include a thin film made of vanadium oxide, indium tin oxide (abbreviated as ITO), molybdenum oxide, or the like.

  In the organic EL element in which the first electrode 32 is used as an anode and the second electrode 33 is used as a cathode, each layer is stacked on the drive substrate 21 in order from the left layer in the configurations a) to q). Conversely, in the organic EL element in which the first electrode 32 is the cathode and the second electrode 33 is the anode, the layers are laminated on the drive substrate 21 in order from the right layer in the configurations a) to q).

<Anode>
In the case of an organic EL element configured to take out light from the light emitting layer through the anode, an electrode exhibiting optical transparency is used for the anode. As the electrode exhibiting light transmittance, a thin film of metal oxide, metal sulfide, metal or the like can be used, and an electrode having high electrical conductivity and light transmittance is preferably used. Specifically, thin films made of indium oxide, zinc oxide, tin oxide, ITO, indium zinc oxide (abbreviated as IZO), gold, platinum, silver, copper, and the like are used. Among these, ITO, IZO Or a thin film made of tin oxide is preferably used. Examples of a method for producing the anode include a vacuum deposition method, a sputtering method, an ion plating method, and a plating method. Further, an organic transparent conductive film such as polyaniline or a derivative thereof, polythiophene or a derivative thereof may be used as the anode.

  The film thickness of the anode is appropriately set in consideration of required characteristics and process simplicity, and is, for example, 10 nm to 10 μm, preferably 20 nm to 1 μm, and more preferably 50 nm to 500 nm.

<Hole injection layer>
As the hole injection material constituting the hole injection layer, oxides such as vanadium oxide, molybdenum oxide, ruthenium oxide, and aluminum oxide, phenylamine type, starburst type amine type, phthalocyanine type, amorphous carbon, polyaniline, And polythiophene derivatives.

  Examples of the method for forming the hole injection layer include film formation from a solution containing a hole injection material. The solvent used for film formation from a solution is not particularly limited as long as it dissolves the hole injection material. Chlorine solvents such as chloroform, methylene chloride, dichloroethane, ether solvents such as tetrahydrofuran, toluene, xylene And aromatic hydrocarbon solvents such as acetone, ketone solvents such as acetone and methyl ethyl ketone, ester solvents such as ethyl acetate, butyl acetate and ethyl cellosolve acetate, and water.

  The film thickness of the hole injection layer is appropriately set in consideration of required characteristics and process simplicity, and is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, and more preferably 5 nm to 200 nm.

<Hole transport layer>
As the hole transport material constituting the hole transport layer, polyvinylcarbazole or a derivative thereof, polysilane or a derivative thereof, a polysiloxane derivative having an aromatic amine in a side chain or a main chain, a pyrazoline derivative, an arylamine derivative, a stilbene derivative, Triphenyldiamine derivative, polyaniline or derivative thereof, polythiophene or derivative thereof, polyarylamine or derivative thereof, polypyrrole or derivative thereof, poly (p-phenylene vinylene) or derivative thereof, or poly (2,5-thienylene vinylene) or Examples thereof include derivatives thereof.

  The method for forming the hole transport layer is not particularly limited, but in the case of a low molecular hole transport material, film formation from a mixed solution containing a polymer binder and a hole transport material can be exemplified. Examples of molecular hole transport materials include film formation from a solution containing a hole transport material.

  The solvent used for film formation from a solution is not particularly limited as long as it can dissolve a hole transport material. Chlorine solvents such as chloroform, methylene chloride, dichloroethane, ether solvents such as tetrahydrofuran, toluene, xylene And aromatic hydrocarbon solvents such as acetone, ketone solvents such as acetone and methyl ethyl ketone, and ester solvents such as ethyl acetate, butyl acetate, and ethyl cellosolve acetate.

  As the polymer binder to be mixed, those that do not extremely inhibit charge transport are preferable, and those that weakly absorb visible light are preferably used. For example, polycarbonate, polyacrylate, polymethyl acrylate, polymethyl methacrylate, polystyrene, poly Examples thereof include vinyl chloride and polysiloxane.

  As the film thickness of the hole transport layer, the optimum value varies depending on the material to be used, the drive voltage and the light emission efficiency are appropriately set to be an appropriate value, and at least a thickness that does not cause pinholes is required, If the thickness is too thick, the drive voltage of the element becomes high, which is not preferable. Therefore, the film thickness of the hole transport layer is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, and more preferably 5 nm to 200 nm.

<Light emitting layer>
The light emitting layer is usually formed of an organic substance that mainly emits fluorescence and / or phosphorescence, or an organic substance and a dopant that assists the organic substance. The dopant is added, for example, in order to improve the luminous efficiency and change the emission wavelength. The organic substance may be a low molecular compound or a high molecular compound. The polymer compound is suitable for the coating method because of its high solubility. Therefore, when the light emitting layer is formed by the coating method, the light emitting layer has a polystyrene-equivalent number average molecular weight of 10 ³ to 10 ⁸ . It is preferable to contain. Examples of the light emitting material constituting the light emitting layer include the following dye materials, metal complex materials, polymer materials, and dopant materials.

(Dye material)
Examples of dye-based materials include cyclopentamine derivatives, tetraphenylbutadiene derivative compounds, triphenylamine derivatives, oxadiazole derivatives, pyrazoloquinoline derivatives, distyrylbenzene derivatives, distyrylarylene derivatives, pyrrole derivatives, thiophene ring compounds. Pyridine ring compounds, perinone derivatives, perylene derivatives, oligothiophene derivatives, oxadiazole dimers, pyrazoline dimers, quinacridone derivatives, coumarin derivatives, and the like.

(Metal complex materials)
Examples of the metal complex material include rare earth metals such as Tb, Eu, and Dy, or Al, Zn, Be, Ir, Pt, etc. as a central metal, and oxadiazole, thiadiazole, phenylpyridine, phenylbenzimidazole, quinoline. Examples include metal complexes having a structure or the like as a ligand, such as iridium complexes, platinum complexes, etc., metal complexes having light emission from a triplet excited state, aluminum quinolinol complexes, benzoquinolinol beryllium complexes, benzoxazolyl zinc A complex, a benzothiazole zinc complex, an azomethylzinc complex, a porphyrin zinc complex, a phenanthroline europium complex, and the like can be given.

(Polymer material)
As polymer materials, polyparaphenylene vinylene derivatives, polythiophene derivatives, polyparaphenylene derivatives, polysilane derivatives, polyacetylene derivatives, polyfluorene derivatives, polyvinylcarbazole derivatives, the above dye materials and metal complex light emitting materials are polymerized. The thing etc. can be mentioned.

(Dopant material)
Examples of the dopant material include perylene derivatives, coumarin derivatives, rubrene derivatives, quinacridone derivatives, squalium derivatives, porphyrin derivatives, styryl dyes, tetracene derivatives, pyrazolone derivatives, decacyclene, phenoxazone, and the like. In addition, the thickness of such a light emitting layer is usually about 2 nm-200 nm.

<Electron transport layer>
As the electron transport material constituting the electron transport layer, known materials can be used, such as oxadiazole derivatives, anthraquinodimethane or derivatives thereof, benzoquinone or derivatives thereof, naphthoquinone or derivatives thereof, anthraquinones or derivatives thereof, tetracyanoanthra Quinodimethane or derivatives thereof, fluorenone derivatives, diphenyldicyanoethylene or derivatives thereof, diphenoquinone derivatives, or metal complexes of 8-hydroxyquinoline or derivatives thereof, polyquinoline or derivatives thereof, polyquinoxaline or derivatives thereof, polyfluorene or derivatives thereof, etc. Can be mentioned.

  There are no particular restrictions on the method for forming the electron transport layer, but for low molecular weight electron transport materials, vacuum deposition from powder or film formation from a solution or a molten state can be used. Examples of the material include film formation from a solution or a molten state. In the case of forming a film from a solution or a molten state, a polymer binder may be used in combination. Examples of the method for forming an electron transport layer from a solution include the same film formation method as the method for forming a hole injection layer from a solution described above.

  The film thickness of the electron transport layer varies depending on the material used, and is set appropriately so that the drive voltage and the light emission efficiency are appropriate, and at least a thickness that does not cause pinholes is required, and is too thick. In such a case, the driving voltage of the element increases, which is not preferable. Therefore, the film thickness of the electron transport layer is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, and more preferably 5 nm to 200 nm.

<Electron injection layer>
As the material constituting the electron injecting layer, an optimal material is appropriately selected according to the type of the light emitting layer, and an alloy containing at least one of alkali metal, alkaline earth metal, alkali metal and alkaline earth metal, alkali A metal or alkaline earth metal oxide, halide, carbonate, or a mixture of these substances can be given. Examples of alkali metals, alkali metal oxides, halides, and carbonates include lithium, sodium, potassium, rubidium, cesium, lithium oxide, lithium fluoride, sodium oxide, sodium fluoride, potassium oxide, potassium fluoride , Rubidium oxide, rubidium fluoride, cesium oxide, cesium fluoride, lithium carbonate, and the like. Examples of alkaline earth metals, alkaline earth metal oxides, halides and carbonates include magnesium, calcium, barium, strontium, magnesium oxide, magnesium fluoride, calcium oxide, calcium fluoride, barium oxide, Examples thereof include barium fluoride, strontium oxide, strontium fluoride, and magnesium carbonate. The electron injection layer may be composed of a laminate in which two or more layers are laminated, and examples thereof include LiF / Ca. The electron injection layer is formed by vapor deposition, sputtering, printing, or the like. The thickness of the electron injection layer is preferably about 1 nm to 1 μm.

<Cathode>
A material for the cathode is preferably a material having a low work function, easy electron injection into the light emitting layer, and high electrical conductivity. Moreover, in the organic EL element of the structure which takes out light from an anode side, in order to reflect the light from a light emitting layer to an anode side with a cathode, the material with a high visible light reflectance is preferable as a material of a cathode. As the cathode, for example, an alkali metal, an alkaline earth metal, a transition metal, a Group 13 metal of the periodic table, or the like can be used. Examples of the cathode material include lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, aluminum, scandium, vanadium, zinc, yttrium, indium, cerium, samarium, europium, terbium, ytterbium, and the like. A metal, two or more alloys of the metals, one or more of the metals, and one or more of gold, silver, platinum, copper, manganese, titanium, cobalt, nickel, tungsten, tin An alloy, graphite, or a graphite intercalation compound is used. Examples of alloys include magnesium-silver alloys, magnesium-indium alloys, magnesium-aluminum alloys, indium-silver alloys, lithium-aluminum alloys, lithium-magnesium alloys, lithium-indium alloys, calcium-aluminum alloys, and the like. it can. As the cathode, a transparent conductive electrode made of a conductive metal oxide or a conductive organic material can be used. Specifically, examples of the conductive metal oxide include indium oxide, zinc oxide, tin oxide, ITO, and IZO, and examples of the conductive organic substance include polyaniline or a derivative thereof, polythiophene or a derivative thereof, and the like. The cathode may be composed of a laminate in which two or more layers are laminated. The electron injection layer may be used as a cathode.

  The film thickness of the cathode is appropriately designed in consideration of required characteristics and process simplicity, and is, for example, 10 nm to 10 μm, preferably 20 nm to 1 μm, and more preferably 50 nm to 500 nm.

  Examples of the method for producing the cathode include a vacuum deposition method, a sputtering method, and a laminating method in which a metal thin film is thermocompression bonded.

(Partition wall)
The partition 51 is made of, for example, an electrical insulating film. The partition wall 51 is made of, for example, SOG (Spin ON Glass), silicon-based insulator such as silicon oxide (SiO ₂ ) and silicon nitride (SiN _X ), aluminum oxide such as alumina (Al ₂ O ₃ ), hafnia (HfO ₂ ), or the like. A single layer composed of a thin film made of hafnium oxide, yttrium oxide such as yttria (Y ₂ O ₃ ), lanthanum oxide such as La ₂ O ₃ , or a photosensitive resin. Or a laminate in which two or more layers are laminated. In addition, as a laminated body, the structure by which the kind of different layer was laminated | stacked may be sufficient, and the structure by which the same kind of layer was laminated | stacked may be sufficient. In the present embodiment, the partition wall 51 may be made of, for example, a photosensitive resin. The partition wall 51 may be light transmissive or non-light transmissive. In the case of providing the light-transmitting partition walls 51, the partition walls 51 may be formed using a material having a high light transmittance as appropriate from the above materials.

(Drive board)
The drive substrate 21 on which the organic EL element 31 is mounted includes a substrate body 22 and a drive circuit 11 formed on the substrate body 22.

  The drive circuit 11 of the present embodiment includes a plurality of circuit elements that individually drive the organic EL elements 31 and predetermined wirings that connect the circuit elements. As shown in FIGS. 2 and 3, the circuit element provided for each organic EL element 31 includes two transistor elements, one capacitor 14, and a predetermined wiring. Hereinafter, one of the two transistor elements is referred to as a switching Tr12, and the other element is referred to as a driving Tr13.

  The switching Tr12 and the driving Tr13 are configured to include gate electrodes SG and DG, source electrodes SS and DS, and drain electrodes SD and DD, respectively. The electrodes of the switching Tr12 and the driving Tr13 are configured by members that exhibit light transmittance. The gate electrodes SG and DG are provided on the substrate body 22. In addition to the gate electrodes SG and DG, predetermined wirings and the like are further provided on the substrate body 22, and the gate electrodes SG and DG and the predetermined wirings are integrally formed. On the substrate body 22, an insulating layer 15 is further provided to cover the gate electrodes SG and DG and predetermined wirings. This insulating layer 15 exhibits light transmittance. A portion of the insulating layer 15 provided on the gate electrodes SG and DG functions as a gate insulating film. The source electrodes SS and DS and the drain electrodes SD and DD are arranged on the gate electrodes SG and DG at a predetermined interval with the insulating layer 15 interposed therebetween. A light-transmitting semiconductor layer 19 is provided between the source electrodes SS and DS and the drain electrodes SD and DD. As described above, in the present embodiment, the bottom gate type switching Tr 12 and the driving Tr 13 are formed on the driving substrate 21, but as another embodiment, a top gate type transistor element may be formed on the driving substrate.

  The capacitor 14 includes a pair of opposed flat plates 14a and 14b and an insulating layer 15 interposed between the pair of flat plates 14a and 14b. One flat plate 14 a is provided on the substrate body 22. The one flat plate 14 a is formed integrally with a predetermined wiring provided on the substrate body 22. The other flat plate 14 b is provided on the insulating layer 15. One flat plate 14a and the source electrode SS of the switching Tr 12 are connected by a conductor in a through hole formed in the insulating layer 15 (hereinafter also referred to as a through-hole wiring portion 16). Further, one flat plate 14a constituting the capacitor 14 is formed integrally with the gate electrode DG of the driving Tr13. Therefore, the source electrode SS of the switching Tr 12 and the gate electrode DG of the driving Tr 13 are electrically connected via the through-hole wiring portion 16 and the capacitor 14. The other flat plate 14b constituting the capacitor 14 is formed integrally with the drain electrode DD of the driving Tr13.

  A planarizing film 17 that covers these elements is further formed on the driving circuit 11 including the driving Tr 13, the switching Tr 12, the capacitor 14, and the like. The plurality of organic EL elements 31 are provided on the planarizing film 17. The source electrode DS of the driving Tr 13 and a predetermined wiring formed on the substrate body 22 are connected via a through-hole wiring portion 18 formed in the insulating layer 15. Further, the predetermined wiring on the substrate body 22 electrically connected to the source electrode DS of the driving Tr 13 passes through through-hole wiring portions 20 a and 20 b provided through the insulating layer 15 and the planarizing film 17. It is electrically connected to the first electrode 32 of the organic EL element 31. Therefore, the first electrode 32 of the organic EL element 31 and the source electrode DS of the driving Tr 13 are electrically connected via predetermined wiring on the substrate body 22 and through-hole wiring portions 18, 20a, 20b.

  The part constituted by the conductor in the drive circuit 11 is constituted by a thin film (hereinafter sometimes referred to as a conductive thin film) that exhibits optical transparency and conductivity, for example, an organic substance or an inorganic oxide conductor. It is preferred that Gate electrodes SG, DG, source electrodes SS, DS, drain electrodes SD, DD of the switching Tr12 and driving Tr13, a pair of flat plates 14a, 14b constituting the capacitor 14, and through-hole wiring portions 16, 18, 20a, 20b In addition, the predetermined wiring corresponds to a portion of the drive circuit 11 that is configured by a conductor. The portion of the drive circuit 11 constituted by the conductor is preferably made of an inorganic oxide conductor. For example, zinc tin oxide (ZTO) or indium-containing oxide (Indium Tin Oxide: ITO) (Indium Zinc Oxide: IZO, etc.) may be used.

  For example, ZTO can be used as a conductor material by increasing the ratio of Sn to Zn in a molar ratio, and the molar ratio of Zn and Sn is preferably 1: 2 (Zn: Sn). When used as a conductor material, ITO has a molar ratio of In to Sn of usually about 9: 1 (In: Sn), and IZO has a molar ratio of In to Zn of usually 9: 1 (In: Zn). )

  It is preferable that the part comprised by the conductor of the drive circuit 11 is comprised by ZTO among these. Since ZTO can form an amorphous thin film, a flexible conductive thin film can be formed. Therefore, by using a thin film made of IZO as the conductive thin film, the flexible drive substrate 21 as a whole can be configured. Furthermore, since an amorphous ZTO thin film can be formed at a relatively low temperature, a member having a low high temperature resistance such as a plastic substrate can be used as the substrate body 22.

The insulating layer 15 is made of an electrically insulating film that exhibits light transmittance. The insulating layer 15 includes, for example, SOG, silicon-based insulators such as silicon oxide and silicon nitride, aluminum oxide such as alumina, hafnium oxide such as hafnia, yttrium oxide such as yttria, lanthanum oxide such as La ₂ O ₃ , Or it is comprised by the thin film which consists of photosensitive resin etc., and is comprised by the single layer body which consists of one layer of these, or the laminated body which laminated | stacked two or more layers. As a laminated body, the structure by which the layer from which a kind differs may be laminated | stacked, and the structure by which the same kind of layer was laminated | stacked may be sufficient. In this embodiment, for example, the insulating layer 15 may be constituted by a laminate of a thin film made of alumina and a thin film made of hafnia.

  The semiconductor layer 19 is constituted by a member exhibiting light transmittance and semiconductivity, and is preferably made of an inorganic oxide semiconductor. Examples of the inorganic oxide semiconductor include zinc tin oxide or indium-containing oxide similar to the predetermined wiring described above, and the semiconductor layer 19 may be formed using a precursor of pentacene or tetrabenzoporphyrin. Good. The semiconductor layer 19 made of an inorganic oxide semiconductor preferably has a carrier concentration lower than the carrier concentration of the predetermined wiring described above.

  Among these, the semiconductor layer 19 is preferably composed of ZTO. For example, ZTO can be used as a semiconductor material by increasing the ratio of Zn to Sn in a molar ratio. For example, the molar ratio of Zn and Sn is preferably 2: 1 (Zn: Sn). The carrier concentration of the semiconductor layer made of ZTO can be controlled by adjusting the atmosphere during film formation. For example, the carrier concentration of the semiconductor layer can be decreased by increasing the oxygen concentration during film formation. Similarly to the above, since IZO can form an amorphous thin film, a flexible semiconductive thin film can be formed. By using a thin film made of IZO as a semiconductor layer, the flexible driving substrate 21 as a whole can be formed. Can be configured.

  In the case where IZO is used as the indium-containing oxide, IZO can be used as a semiconductor material by setting the molar ratio of In to Zn to about 4: 6 (In: Zn).

  The planarizing film 17 can be formed of a thin film similar to that exemplified for the insulating layer 15. In the present embodiment, for example, the planarizing film 17 may be formed of an insulating film having a single layer structure formed using a photosensitive resin.

  The operation of the display device 1 will be described below with reference to FIG. A scanning signal (indicated by the symbol “Vscan” in FIG. 3) and a data signal (indicated by the symbol “Vsig” in FIG. 3) are input to the drive substrate 21 from a signal generation unit provided in the display device 1. These scanning signals and data signals are input to circuit elements that drive the individual organic EL elements 31. In the present embodiment, the above-described predetermined wiring includes main wirings m1 and m2 that transmit scanning signals and data signals, and sub wirings s1 and s2 that branch from the main wirings m1 and m2.

  In the present embodiment, the main wirings m <b> 1 and m <b> 2 are disposed between the substrate body 22 and the partition wall 51. For example, the main wiring m1 for transmitting the scanning signal is composed of a plurality of conductors extending in the row direction X, and is disposed at a position overlapping the plurality of partition walls 51 extending in the row direction X in plan view. Further, for example, the main wiring m2 for transmitting a data signal is constituted by a plurality of conductors extending in the column direction Y, and is disposed at a position overlapping the plurality of partition walls 51 extending in the column direction Y in plan view. The main wiring m1 for transmitting the scanning signal and the main wiring m2 for transmitting the data signal are spaced apart from each other in the thickness direction of the drive substrate 21 and extend so that they do not intersect with each other. Arranged.

  The sub-wiring s1 branched from the main wiring m1 that transmits the scanning signal is connected to the gate electrode SG of the switching Tr12, and is formed integrally with the gate electrode SG of the switching Tr12 on the substrate body 22, for example. The sub-wiring s2 branched from the main wiring m2 that transmits the data signal is connected to the drain electrode SD of the switching Tr12, and is formed integrally with the drain electrode SD of the switching Tr12 on the insulating layer 15, for example.

  The source electrode SS of the switching Tr12 and the gate electrode DG of the driving Tr13 are connected by a predetermined wiring. A capacitor 14 is inserted between the gate electrode DG and the drain electrode DD of the driving Tr 13. The source electrode DS of the driving Tr 13 and the first electrode 32 of the organic EL element 31 are connected by wiring. A drive voltage (indicated by symbol “Vcc” in FIG. 3) from a drive power supply is applied to the drain electrode DD of the drive Tr 13.

  When a high voltage is applied as a scanning signal to the gate electrode SG of the switching Tr 12 via the main wiring m1 and the sub wiring s1, the drain electrode SD and the source electrode SS may be in a conductive state (hereinafter referred to as an on state). .)become. When a high voltage is applied as a data signal to the drain electrode SD of the switching Tr 12 via the main wiring m and the sub wiring s when the switching Tr 12 is in the on state, the high voltage data signal is applied to the gate of the driving Tr 13. Given to the electrode DG, the drain electrode DD and the source electrode DS become conductive (on state). When the driving Tr 13 is turned on, the driving voltage (Vcc) is applied to the first electrode 32 of the organic EL element 31 and the organic EL element 31 emits light. That is, the driving Tr 13 is turned on in a state where both the scanning signal and the data signal are input, and the organic EL element 31 emits light.

  In a state where no scanning signal is input, that is, a state where a low voltage is applied to the gate electrode SG of the switching Tr12, the drain electrode SD and the source electrode SS of the switching Tr12 are in a non-conductive state (hereinafter referred to as an off state). There are things.) Even if a high voltage is applied as a data signal to the drain electrode SD of the switching Tr12 when the switching Tr12 is in the OFF state, the high voltage data signal is not applied to the gate electrode DG of the driving Tr13. The drain electrode DD and the source electrode DS of the transistor Tr13 are in a non-conductive state (off state). Further, even when the switching Tr12 is in an ON state in a state where a high voltage is input as a scanning signal, the drain electrode of the switching Tr12 is connected to the gate electrode DG of the driving Tr13 in a state where no data signal is input. Since a low voltage is applied as in the case of SD, the driving Tr 13 is turned off. Therefore, in a state where no scanning signal or data signal is input, the driving Tr 13 is turned off, so that the organic EL element 31 does not emit light. As described above, since the organic EL element 31 emits light only when both the scanning signal and the data signal are input, the organic EL element can be selectively input by inputting the scanning signal and the data signal. 31 can selectively emit light.

  In the display device 1 of the present embodiment, a plurality of organic EL elements 31 are arranged in a matrix, and the circuit elements shown in FIG. 3 are provided for each organic EL element 31. The gate electrodes SG of the circuit element switching Tr 12 provided in the organic EL elements 31 of each row are connected to each other by a main wiring m1 that transmits a scanning signal to each other. The drain electrodes SD of the circuit element switching Tr 12 provided in the organic EL elements 31 of each column are connected to each other by a wiring m2 that transmits a data signal to each other. Therefore, a common scanning signal is input to the gate electrode SG of the switching Tr 12 arranged in the same row. A common data signal is input to the drain electrode SD of the switching Tr 12 arranged in the same column. In such an active matrix display device 1, a plurality of organic EL elements 31 arranged in a specific row can be selected by inputting a scanning signal. By inputting a data signal from the plurality of organic EL elements 31 selected in this way, the organic EL elements 31 arranged in a specific column can selectively emit light.

  As described above, by configuring the drive circuit 11 with the light transmissive member, it is possible to configure the light transmissive drive circuit 11. Note that the drive circuit 11 only needs to be configured by a member that exhibits at least light transmission in a plan view, and a portion that overlaps the region where light is emitted from the organic EL element 31 is formed. For example, all of the drive circuit 11 has light transmission. You may be comprised by the member to show, and one part may be comprised by the member which shows a light transmittance. For example, in the drive circuit 11, the main wirings m <b> 1 and m <b> 2 provided at a position overlapping the partition wall 51 in a plan view may be configured by an opaque member, and other portions may be configured by a member that exhibits light transmittance. In this embodiment, since the organic EL element 31 is formed in a region excluding the partition wall 51, even if the main wirings m1 and m2 provided at positions overlapping the partition wall 51 in plan view are opaque, the main wirings m1 and m2 Thus, the aperture ratio of the organic EL element 31 is not limited. Therefore, for example, the main wirings m1 and m2 can be configured using a member that is opaque but has a relatively low electrical resistance. As a result, power wasted in the drive circuit 11 can be suppressed. For example, the main wirings m1 and m2 having low electrical resistance can be formed by increasing the layer thickness. The main wirings m1 and m2 may be formed of a material different from that of the sub-wirings s1 and s2 exhibiting light transmittance, and may be formed using, for example, a metal having low resistivity.

  As described above, by using the drive circuit 11 in which the portion overlapping the region where light is emitted from the organic EL element 31 in a plan view is configured by a member having light transmittance, the aperture ratio of the organic EL element 31 is set to the drive circuit 11. It can prevent being restricted by. Therefore, it is not necessary to arrange an organic EL element so as not to overlap with an opaque driving circuit in a plan view, and a high aperture ratio can be ensured without reducing the degree of design freedom.

(the film)
The film 41 is disposed with the drive substrate 21 interposed between the plurality of organic EL elements 31. In other words, the film 41 is disposed on the side opposite to the side where the plurality of organic EL elements 31 are provided with respect to the drive substrate 21. In the present embodiment, the film 41 is disposed in contact with the drive substrate 21. A predetermined layer may be provided between the drive substrate 21 and the film 41.

  The surface of the film 41 opposite to the drive substrate 21 has an uneven shape, and the uneven surface forms an interface with the atmosphere. That is, the film 41 is provided as the outermost layer in contact with air in the display device 1. This film 41 has a haze value of 70% or more and a total light transmittance of 50% or more. The upper limit of the total light transmittance and the haze value is 100%, but these are set as appropriate according to the specifications of the apparatus in which the organic EL element 31 is incorporated.

  In the present embodiment, the film 41 is attached to the drive substrate 21 with a predetermined bonding agent such as a thermosetting resin, a photocurable resin, an adhesive, or an adhesive material. In addition, when forming the film 41 directly on the drive board | substrate 21, it is not necessary to use a bonding agent, and when bonding agent is previously provided in the film 41, when bonding the film 41, It is not necessary to arrange a bonding agent between the film 41 and the driving substrate 21.

  When an air layer is formed between the film 41 and the drive substrate 21 when the film 41 is bonded, light is reflected at the interface between the air layers. Therefore, the light extraction efficiency is increased due to this reflection. descend. Therefore, it is preferable that the film 41 is bonded to the drive substrate 21 so that an air layer is not formed between the film 41 and the drive substrate 21. Of the refractive index of the layer (drive substrate 21 in this embodiment) to which the film 41 is bonded, the bonding agent, and the film 41, the absolute value of the difference between the maximum refractive index and the minimum refractive index is The smaller one is preferable because reflection can be suppressed, specifically 0.2 or less, more preferably 0.1 or less.

  The film 41 of the present embodiment has an uneven surface on the side opposite to the drive substrate 21 side, has a haze value of 70% or more, and a total light transmittance of 50% or more. If the haze value is less than 70%, a sufficient light scattering effect may not be obtained, and if the total light transmittance is less than 50%, light may not be sufficiently extracted. May be unable to obtain sufficient light extraction efficiency when used in an organic EL device, but by using the film 41 having a haze value of 70% or more and a total light transmittance of 50% or more, a high extraction efficiency is obtained. The organic EL element can be realized. The total light transmittance of the film 41 is more preferably 80% or more.

  The haze value is expressed by the following formula, and can be measured by the method described in JIS K 7136 “Plastics—How to determine haze of transparent material”.

Haze value (cloudiness value) = (diffuse transmittance (%) / total light transmittance (%)) × 100 (%)
The total light transmittance can be measured by the method described in JIS K 7361-1 “Testing method of total light transmittance of plastic-transparent material”.

  If the average of the size (width) of the convex or concave surface in the width direction perpendicular to the thickness direction of the film 41 is too large, the luminance on the surface of the film 41 becomes non-uniform, and if it is too small, the production cost of the film 41 increases. Therefore, it is preferably the same as or larger than the wavelength of light, preferably 0.1 μm to 100 μm, more preferably 0.5 μm to 20 μm, and further preferably 1 μm to 2 μm. Further, the average height of the convex surface or concave surface in the thickness direction of the film 41 is appropriately set according to the size (width) of the convex surface or concave surface in the width direction and the period in which the uneven shape is formed. It is preferably not more than the size (width) of the concave surface or the convex surface, or not more than the period in which the concavo-convex shape is formed.

  The shape of the convex surface or the concave surface is preferably a shape having a curved surface, and preferably a hemispherical shape. The concave surface or the convex surface is preferably arranged regularly, for example, preferably arranged in a grid pattern. Moreover, the ratio of the area | region where a concave surface and a convex surface are formed in the surface of the film 41, in other words, the ratio of the area | region except a planar-shaped area | region, 60% or more of the area of the film 41 surface is preferable in planar view.

  The material of the film 41 should just be a material which can form the film 41 which shows light transmittance, for example, may use inorganic materials and organic materials, such as glass. Examples of the organic material include polyarylate, polycarbonate, polycycloolefin, polyethylene naphthalate, polyethylene sulfonic acid, and polyethylene terephthalate. The film 41 may be composed of only one layer, or may be composed of a laminate in which a plurality of layers are laminated. The film 41 includes, for example, a support formed using glass or the organic material, and a thin film formed on the surface of the support, and the surface opposite to the surface in contact with the support is formed in an uneven shape. You may be comprised with a laminated body.

  Although there is no restriction | limiting in particular in the thickness of the film 41, since handling will become difficult if too thin, and a total light transmittance will become low when too thick, 20 micrometers-1000 micrometers are preferable.

  The film 41 made of an inorganic material such as glass can be obtained by etching a flat base made of an inorganic material. For example, it can be obtained by selectively etching a portion forming a concavo-convex shape on a flat base surface. Specifically, a concavo-convex surface can be formed by patterning a protective film on the surface of a base made of an inorganic material and performing liquid phase etching or gas phase etching. The protective film can be patterned using, for example, a photoresist.

  In the film 41 made of an organic material, an uneven shape can be formed on the surface by, for example, the following methods (1) to (6). (1) A method of transferring the concavo-convex shape of the metal plate by pressing the concavo-convex metal plate against a heated film. (2) A method of rolling a polymer sheet or film using a roll having an uneven surface. (3) A method of extruding a polymer sheet from a slit having an uneven shape. (4) A method of forming a film by dropping a solution or dispersion containing an organic material onto a base having an uneven surface (hereinafter sometimes referred to as casting). (5) A method in which after forming a film made of a polymerizable monomer, a part of the film is selectively photopolymerized to remove an unpolymerized part. (6) A method in which a polymer solution is cast on a base under high humidity conditions, and a water droplet structure is transferred to the surface.

  As the method (6) for transferring the water droplet structure to the surface, the uneven film 41 can be produced relatively easily. Therefore, the method (6) is preferable among the methods described above. The method (6) is a structure manufacturing method applying a dissipative process which is a kind of self-organization (for example, G. Widawski, M. Rawiso, B. Francois, Nature, p. 369-p. 387 (1994)). reference).

  First, the organic material to be the film 41 described above is dissolved in a solvent to prepare a solution for forming the film 41. Examples of the solvent include dichloromethane and chloroform. The viscosity of the solution for forming the film 41 is preferably higher. The concentration of the organic material to be the film 41 in the solution for forming the film 41 is preferably high, and the concentration of the organic material in the solution is preferably 10 wt% or more. In order to improve the size and shape uniformity of the uneven shape, a small amount of a surfactant such as a nonionic surfactant may be added to the solution for forming the film 41.

  Next, a solution containing a material to be the film 41 is applied to a predetermined base. Specifically, the prepared solution for forming the film 41 is cast on a predetermined base under high humidity to form a liquid film composed of the solution for forming the film 41. When the drive substrate 21 is used as a base for casting the solution for forming the film 41, that is, when the solution for forming the film 41 is directly cast on the drive substrate 21, the film 41 is directly formed on the drive substrate 21. Is done.

  After casting the solution, the humidity of the base atmosphere is maintained at 80% to 90% for a predetermined time. When the base is placed in an atmosphere having such a high humidity, water vapor in the atmosphere is liquefied, and a plurality of liquefied liquid droplets are formed on the liquid film. These droplets are substantially spherical and are discretely formed on the surface of the liquid film. The droplets formed on the liquid film grow and increase with time due to further liquefaction of water vapor, and the weight of the droplets increases. Therefore, almost half of the droplet sinks into the liquid film due to its own weight. In parallel with the formation of droplets, the solvent (solvent) in the liquid film evaporates with time, so the viscosity of the liquid film increases with time. In this way, the droplets are immersed in the liquid film and the viscosity of the liquid film is increased, so that the shape of the droplets is transferred to the film 41 during drying. The film 41 formed in this way is formed in a concavo-convex shape with a plurality of concave surfaces provided on the surface. Specifically, a plurality of hemispherical depressions having an average diameter of 1 μm to 100 μm are formed on the surface of the film 41. The film 41 may be dried by holding the film 41 in the range of 80% to 90%, and further keeping the humidity of the film atmosphere low after the formation of the hemispherical depression on the surface. Further, the film may be dried by keeping the humidity of the film atmosphere at 80% to 90% for a long time.

  In the method for producing the film 41 described above, the application of the solution for forming the film 41 is controlled so that the film 41 thickness after the production becomes a predetermined value, and the humidity when the liquid film is dried is adjusted. Thus, the haze value of the produced film 41 can be controlled.

  Specifically, the thickness of the liquid film at the start of drying is controlled so that the thickness of the film 41 after the production becomes a predetermined thickness within the range of 100 μm to 200 μm, and within the range of 80% to 90%. By controlling the humidity so as to be a predetermined humidity, the film 41 having a desired haze value of 70 or more can be formed.

  The haze value of the film 41 can be controlled by controlling the humidity and the film thickness, depending on the concentration of the organic material, etc., but changing the humidity and the film thickness until the surface of the liquid film is dried. This is because the size of the concave-convex shape and the density of the concave surface change accordingly, and the humidity greatly affects the structure construction of the concave surface to be formed, such as improving the regularity of the concave surface arrangement. Presumed to be.

  The film thickness of the film 41 after production can be controlled by adjusting the film thickness of the liquid film at the start of drying. Moreover, since the time until the surface of the liquid film is dried depends on the evaporation rate of the solvent (solvent) and the boiling point of the solvent (solvent), the haze value of the film 41 is controlled by changing the solvent (solvent) to be used. You can also.

  As described above, it is possible to produce a large-area film 41 exhibiting the desired optical characteristics by simple control of adjusting the coating amount and humidity of the solution, and the water droplet structure of (6) above is formed on the surface. By the transferring method, the film 41 having a large area can be produced easily and inexpensively.

  As described above, the film 41 can be formed directly on the drive substrate 21 by casting the solution for forming the film 41 on the surface of the drive substrate 21. However, the film is formed on a predetermined base. After that, the film 41 may be bonded to the drive substrate 21.

  According to the above-described configuration, the film 41 is disposed on the outermost surface portion of the display device 1 on the side where the light from the organic EL element 31 is emitted. Therefore, the light emitted from the organic EL element 31 passes through the driving substrate 21 and the film 41, passes through the film surface (hereinafter, referred to as an emission surface) formed in a concavo-convex shape, and is emitted to the outside such as air. To do.

  If the exit surface of the film 41 is flat, most of the light emitted from the organic EL element 31 does not exit to the outside due to total reflection or the like occurring on the exit surface, but the surface of the film 41 is uneven in this embodiment. Since it is formed in a shape, total reflection or the like occurring on the exit surface can be suppressed. Therefore, light can be emitted efficiently. In particular, since the film 41 of the present embodiment has a haze value of 70% or more and a total light transmittance of 50% or more, the light extraction efficiency can be improved. Thereby, an organic EL element having high light extraction efficiency and light emission efficiency can be realized.

  The surface of the film 41 is provided with a plurality of concave surfaces, and these concave surfaces exhibit the same function as the concave lens. By providing such a film 41, the radiation angle of the light emitted from the organic EL element can be widened.

  Further, as described above, the aperture ratio of the organic EL element 31 can be improved by forming the drive circuit 11 exhibiting light transmittance. In the drive circuit 11, not only the thin film transistor but also predetermined wirings and capacitors are configured by members that exhibit light transmittance. Therefore, even if the bottom emission type organic EL element 31 that emits light to the drive substrate 21 side is arranged so as to overlap the drive circuit 11 in plan view, the aperture ratio of the element is not limited by the drive circuit 11. A display device 1 including an organic EL element 31 having a high aperture ratio can be realized.

  The area allocated as a region in which each organic EL element 31 is provided is naturally determined from specifications such as resolution. The light emitting area of each organic EL element 31 is limited to the area allocated to each element at the maximum, but the light emitting area of each element is further limited by the aperture ratio. In the present embodiment, by increasing the aperture ratio of the organic EL element 31, the light emission area can be made as wide as possible, with the area allocated to each element as a limit. If the light intensity of the entire element is compared to be constant, the luminance can be suppressed as the light emitting area increases. Therefore, by increasing the aperture ratio as in the present embodiment, the current flowing through each organic EL element 31 during driving is increased. The density can be lowered. Further, by improving the light extraction efficiency, it is possible to suppress the intensity of light that should be emitted from the organic EL element 31 toward the drive substrate 21, thereby further reducing the current density flowing through each organic EL element 31 during driving. be able to. Thus, by increasing the aperture ratio and improving the light extraction efficiency, the current density during driving can be suppressed, and the load applied to the organic EL element can be reduced. Thereby, the lifetime of the element can be improved.

(2) Manufacturing Method of Organic EL Device Next, a manufacturing method of the organic EL device will be described.

(Drive board)
First, a plate-like substrate body 22 that exhibits light transmittance and insulation is prepared. As the substrate body 22, for example, a glass substrate, a quartz substrate, a plastic substrate, and a substrate in which these are laminated can be used. Further, by using, for example, a flexible substrate as the substrate body 22, a flexible device as a whole can be realized.

  Next, a conductive thin film is formed on one surface of the substrate body 22 in the thickness direction. The conductive thin film is formed by, for example, a sputtering method, a CVD (Chemical Vapor Deposition) method, or a vacuum deposition method. In this embodiment, an amorphous ZTO conductive thin film exhibiting optical transparency is formed. For example, as described above, an amorphous ZTO conductive thin film having a molar ratio of Zn and Sn of 1: 2 (Zn: Sn) is formed.

  Next, the ZTO conductive thin film is patterned by, for example, photolithography. Thus, one flat plate 14a constituting the capacitor 14, the gate electrode SG of the switching Tr12, the gate electrode DG of the driving Tr13, and a predetermined wiring are formed. These conductive thin films can also be formed by, for example, a printing method using a sol-gel method or a coating method such as an ink jet printing method.

  Next, for example, alumina and hafnia are sequentially deposited by sputtering, CVD, vacuum evaporation, or the like, and the insulating layer 15 exhibiting optical transparency is formed. Further, a through hole is formed in a predetermined portion of the insulating layer 15 by photolithography. This through hole is formed in a portion where the through-hole wiring portions 16, 18, 20a and the like are provided. Instead of forming the through hole after forming the insulating layer 15, the insulating layer 15 may be selectively formed only in a region excluding the part where the through hole is formed, for example, by a printing method. The photolithography process can be omitted. The insulating layer 15 thus formed functions as a gate insulating film for the switching Tr 12 and the driving Tr 13 and an insulating film for the capacitor 14.

  Next, a conductive thin film is formed on the insulating layer 15. This conductive thin film is formed, for example, by sputtering, CVD (Chemical Vapor Deposition), or vacuum deposition. In this embodiment, an amorphous ZTO conductive thin film exhibiting optical transparency is formed. For example, as described above, an amorphous ZTO conductive thin film having a molar ratio of Zn and Sn of 1: 2 (Zn: Sn) is formed. When forming the ZTO conductive thin film, the through hole formed in the insulating layer 15 is also provided with a conductor made of ZTO, so that the through-hole wiring portions 16, 18, and 20a are also formed in this step simultaneously with the conductive thin film. It is formed.

  Next, the ZTO conductive thin film is patterned by, for example, photolithography. Thereby, the source electrodes SS and DS, the drain electrodes SD and DD of the switching Tr 12 and the driving Tr 13, the other flat plate 14 b constituting the capacitor 14, and predetermined wiring are formed. These conductive thin films can also be formed by, for example, a printing method using a sol-gel method or a coating method such as an ink jet printing method.

  Next, a semiconductor thin film exhibiting optical transparency is formed by depositing a semiconductor using, for example, a sputtering method, a CVD method, or a vacuum evaporation method. In this embodiment, a semiconductor thin film can be formed by depositing ZTO. For example, the molar ratio of Zn to Sn is 2: 1 (Zn: Sn), and the carrier concentration is lower than that of the ZTO conductive thin film. A thin film is formed. The carrier concentration of the ZTO thin film can be controlled by adjusting the oxygen concentration of the atmosphere during film formation as described above.

  Next, by patterning the ZTO semiconductor thin film by, for example, photolithography, the semiconductor layer 19 is selectively formed between the source electrodes SS and DS and the drain electrodes SD and DD of the switching Tr12 and the driving Tr13. The semiconductor layer 19 thus formed functions as a channel layer for the switching Tr12 and the driving Tr13.

  The semiconductor layer 19 in the present embodiment is preferably formed so as to cover the ZTO conductive thin film patterned on the insulating layer 15. In this embodiment, since the ZTO conductive thin film and the ZTO semiconductor thin film patterned on the insulating layer 15 are formed using the same type of material, both thin films have the same resistance to the etchant. Therefore, it is difficult to selectively etch only the ZTO semiconductor thin film, and when the ZTO semiconductor thin film is etched, a part of the ZTO conductive thin film may be removed. However, since the semiconductor layer 19 functions as a protective film for the ZTO conductive thin film in the etching process by forming the semiconductor layer 19 so as to cover the ZTO conductive thin film as in this embodiment, the ZTO conductive thin film is etched. Can be prevented. Instead of forming the semiconductor layer 19 by patterning after forming the ZTO semiconductor thin film, for example, the semiconductor layer 19 may be selectively formed only at a portion where the semiconductor layer 19 is formed. The lithography process can be omitted.

  Further, since the ZTO conductive thin film and the ZTO semiconductor thin film are formed using the same type of material, the source electrodes SS and DS and the drain electrodes SD and DD of the switching Tr12 and the driving Tr13 and the semiconductor layer 19 are excellent. Can be in ohmic contact. As a result, the contact resistance can be reduced, and as a result, the power consumption of the display device 1 can be reduced.

  Next, a planarizing film 17 that covers the insulating layer 15 is formed. For example, a photoresist is applied by spin coating, a predetermined portion is exposed, and development and curing are performed. In this way, the planarizing film 17 having through holes formed in predetermined portions is formed. This through hole is formed in a portion where the through-hole wiring portion 20b and the like are provided.

  Next, a conductor is formed in the through-hole formed in the planarizing film 17, and the through-hole wiring part 20b is formed. For example, a conductor can be formed only in the through hole by forming a ZTO conductor thin film on the planarizing film 17 in the same manner as described above and further removing a predetermined portion by photolithography. In addition, you may make it provide a conductor in a through-hole at the same process as the process of forming the 1st electrode 32 of the organic EL element 31.

  The drive substrate 21 is manufactured by the process described above.

(Organic EL device)
Next, the organic EL element 31 is produced.

  First, the first electrode 32 is formed. The first electrode 32 is provided independently for each organic EL element 31 and is formed in an island shape on the planarizing film 17. For example, the first electrode 32 may be formed by forming a light-transmitting conductive thin film by, for example, vacuum deposition, sputtering, or ion plating, and then patterning the conductive thin film into an island shape by photolithography. it can. As described above, the through-hole wiring portion 20b described above is formed in the same process as the first electrode 32, and the first electrode 32 and the through-hole wiring portion 20b are integrally formed. Good. The first electrode 32 is electrically connected to the drive circuit 11 through the through-hole wiring portions 20a and 20b.

  For example, the first electrode 32 functioning as an anode can be formed by sequentially laminating a layer made of ZTO, a layer made of Ag, and a layer made of ZTO.

  Next, the partition wall 51 is formed on the drive substrate 21 on which the first electrode 32 is formed. For example, by applying a photoresist by spin coating, exposing a predetermined portion, developing, and curing, it is possible to form a grid-like partition wall 51 that partitions each organic EL element 31.

  Next, one or more predetermined layers 34 are formed on the first electrode 32. The one or more predetermined layers 34 include at least a light emitting layer. One or a plurality of predetermined layers can be formed by selectively depositing the material constituting each layer on the first electrode 32. Examples of film forming methods include coating methods, vapor deposition methods, laser transfer and thermal transfer methods. Examples of coating methods include inkjet printing methods, gravure printing methods, screen printing methods, flexographic printing methods, offset printing methods, and reversal methods. Examples thereof include a printing method and a nozzle coating method. For example, one or a plurality of predetermined layers 34 can be formed by selectively applying an ink containing a material to be a predetermined layer by the predetermined application method and further solidifying the applied film by heat treatment or the like.

  Next, the second electrode 33 is formed on the one or more layers 34. In the present embodiment, the second electrode 33 straddling the organic EL elements 31 is formed. That is, the second electrode 33 connected to the entire surface is integrally formed on one or a plurality of layers 34 of each organic EL element 31. For example, the second electrode 33 functioning as a cathode can be formed by depositing an alloy material of Mg and Ag by a vacuum evaporation method or the like.

Next, a protective film for protecting the organic EL element 31 is formed as necessary. For example, a multilayer film of SiO ₂ or SiN _x is formed by a CVD method or the like.

(the film)
The film 41 is produced by the method described above, and this is further affixed to the drive substrate 21.

  Thus, the display device 1 can be manufactured.

  The drive circuit 11 is disposed between the substrate body 22 and the organic EL element 31 at a position where at least a part thereof overlaps the organic EL element 31 in plan view. The organic EL element 31 is preferably formed on a flat surface because its characteristics depend on the uniformity of the thickness of each layer. Since the portion where the drive circuit is provided has irregularities depending on its thickness, in order to provide the organic EL element on the drive circuit, it is necessary to perform a predetermined process such as forming a planarization film. However, when the drive circuit is opaque, the light emitted from the organic EL element is blocked by the drive circuit. Therefore, the organic EL element is not formed on the drive circuit. An organic EL element is provided in a region avoiding a region where a circuit is formed. Then, the aperture ratio of the organic EL element inevitably decreases by the area occupied by the drive circuit. In this embodiment, the drive circuit 11 that transmits light is used and the organic EL element 31 is driven in a plan view. By arranging it over the circuit 11, the aperture ratio of the organic EL element 31 can be improved. In addition, since the main wiring that constitutes a part of the drive circuit and the sub wiring that branches from the main wiring have irregularities depending on the thickness thereof, when these wirings are opaque, for the same reason as described above, Since the organic EL element was formed so as not to overlap the wiring, as a result, the aperture ratio of the organic EL element was lowered and the degree of freedom of design was reduced. In plan view, an organic EL element can be formed on the wiring, the aperture ratio can be improved, and the degree of freedom in design can be improved.

  In the following Production Examples 1 and 2 and Comparative Examples 1 to 3, it was confirmed that the light extraction efficiency can be controlled by providing a film having predetermined optical characteristics on the outermost surface portion.

(Production Example 1)
A 30 mm × 30 mm glass substrate was used as a transparent support substrate. An ITO thin film having a thickness of 150 nm was formed on the surface of the support substrate by sputtering. A photoresist was coated on the ITO thin film, a predetermined region was exposed through a photomask, and further washed to form a protective film having a predetermined pattern shape. After further etching, rinsing was performed with water and NMP (n-methylpyrrolidone) to form an anode made of an ITO thin film having a predetermined pattern shape. Next, in order to remove the resist residue on the anode, oxygen plasma treatment was performed at an energy of 30 W for 2 minutes, and UV / O ₃ cleaning was performed for 20 minutes.

  Next, the suspension of poly (3,4) ethylenedioxythiophene / polystyrene sulfonic acid (trade name: BaytronP CH8000, manufactured by Starck Vitec Co., Ltd.) is subjected to two-stage filtration to prepare a solution for the hole injection layer. Obtained. A 0.45 μm diameter filter was used for the first stage filtration, and a 0.2 μm diameter filter was used for the second stage filtration. The solution obtained by filtration was applied on the anode by spin coating, and heat-treated at 200 ° C. for 15 minutes on a hot plate in an air atmosphere to form a hole injection layer having a thickness of 70 nm.

  Next, Lumination WP1330 (manufactured by SUMATION) and xylene were mixed to prepare a xylene solution. The concentration of Lumation WP1330 in the xylene solution was 1.2 mass%. The prepared solution was applied onto the hole injection layer by spin coating, and heat-treated on a hot plate at 130 ° C. for 60 minutes in a nitrogen atmosphere to form a light emitting layer having a thickness of 80 nm.

The support substrate on which the light emitting layer was formed was introduced into a vacuum deposition machine, and Ba and Al were sequentially deposited at a thickness of 5 nm and 80 nm, respectively, to form a cathode. The metal deposition was started after the degree of vacuum reached 1 × 10 ⁻⁴ Pa or less.

  Next, a film was produced. First, a solution for film formation was prepared. 6.32 g of polycarbonate was dissolved in 20.7 g of dichloromethane to prepare a 23.4 wt% solution. Novec (manufactured by Sumitomo 3M) was mixed with this solution as a fluorosurfactant to obtain a film-forming solution. The concentration of Novec in the mixed solution was 0.8 wt%. The obtained film-forming solution was cast on a glass base in a constant temperature and humidity chamber having a humidity of 85%. The cast amount of the film-forming solution was adjusted so that the film thickness after film formation was about 150 μm. After being left in an atmosphere of 85% humidity for 5 minutes, the film was dried by nitrogen flow to obtain a 20 mm × 20 mm film (film A) having a concavo-convex shape on the surface.

  Next, glycerin was applied as a pressure-sensitive adhesive to the surface of the support substrate opposite to the surface on which the light emitting layer was formed, and film A was bonded to produce an organic EL device. The support substrate has a refractive index of 1.50, the adhesive has a refractive index of 1.45, and the film A has a refractive index of 1.58. The average film thickness of film A is 150 μm.

(Production Example 2)
An organic EL element that is different from the organic EL element of Production Example 1 only in film was produced. In Production Example 2, a commercially available film (film B) showing a high haze value (82) was used. Since the film B has an adhesive layer, an organic EL element was produced by directly attaching the film B to a supporting substrate without using an adhesive or the like.

(Comparative Example 1)
An organic EL element that is different from the organic EL element of Production Example 1 only in film was produced. The same solution as in Preparation Example 1 was used as the film forming solution. In a constant temperature and humidity chamber with a humidity of 50%, the film-forming solution was cast on a glass base so that the film thickness after film formation was about 220 μm. After being left in an atmosphere of 50% humidity for 5 minutes, the film was dried by nitrogen flow to obtain a 20 mm × 20 mm film (film C). Using the same adhesive as in Production Example 1, film C was attached to a support substrate in the same manner as in Production Example 1 to produce an organic EL device.

(Comparative Example 2)
An organic EL element that is different from the organic EL element of Production Example 1 only in film was produced. The same solution as in Preparation Example 1 was used as the film forming solution. In a constant temperature and humidity chamber with a humidity of 85%, the film-forming solution was cast on a glass base so that the film thickness after film formation was about 220 μm. After leaving it in an atmosphere with a humidity of 85% for 5 minutes, the film was dried with a nitrogen flow to obtain a 20 mm × 20 mm film (film D) having an uneven shape on the surface. Using the same adhesive as in Production Example 1, film D was attached to a supporting substrate in the same manner as in Production Example 1 to produce an organic EL device.

(Comparative Example 3)
An organic EL element that is different from the organic EL element of Production Example 1 only in film was produced. The same solution as in Preparation Example 1 was used as the film forming solution. In a constant temperature and humidity chamber with a humidity of 85%, the film forming solution was cast on a glass base so that the film thickness after film formation was about 360 μm. After being left in an atmosphere of 85% humidity for 5 minutes, the film was dried by nitrogen flow to obtain a 20 mm × 20 mm film (film E) having an uneven shape on the surface. Using the same pressure-sensitive adhesive as in Production Example 1, film E was attached to a supporting substrate in the same manner as in Production Example 1 to produce an organic EL device.

(Observation of film surface)
The surfaces of the films used in Production Examples 1 and 2 and Comparative Examples 1, 2, and 3 were observed with a scanning electron microscope (SEM). 4 is a diagram schematically showing a cross section of the film A produced in Production Example 1, FIG. 5 is a diagram schematically showing a cross section of the film B used in Production Example 2, and FIG. It is a figure which shows typically the cross section of the film C produced in.

  In the film A produced in Production Example 1, it was confirmed that a hemispherical concave surface having an average diameter of 2 μm was formed on the surface of the film. It was confirmed that a concave surface was formed over the entire surface of the film A.

  In the film B used in Preparation Example 2, it was confirmed that the surface of the film was formed in an uneven shape. It was confirmed that a concave surface was formed over the entire surface of the film B.

  In the film C produced in Comparative Example 1, it was confirmed that the surface was flat without forming a concave surface on the surface.

  In the film D produced in Comparative Example 2, it was confirmed that a hemispherical concave surface having an average diameter of 3 μm was formed on the surface of the film. Although the regularity of the arrangement of the concave surface was relatively low, it was confirmed that the concave surface was formed over the entire surface of the film D.

  In the film E produced in Comparative Example 3, it was confirmed that a hemispherical concave surface having an average diameter of 4 μm was formed on the surface of the film. Although the regularity of the arrangement of the concave surface was relatively low, it was confirmed that the concave surface was formed over the entire surface of the film E.

  Table 1 shows the humidity when the films were produced in Production Example 1 and Comparative Examples 1, 2, and 3, and the characteristics of the films used in Production Examples 1, 2 and Comparative Examples 1, 2, and 3.

  As shown in Table 1, it was confirmed that a film having a high haze value can be produced by controlling the film thickness and humidity of the produced film. Moreover, when the film thickness of the produced film became thick, it confirmed that the diameter of the concave surface became large.

(Light extraction efficiency of organic EL elements)
The light intensity of the organic EL element to which the films prepared in Production Examples 1 and 2 and Comparative Examples 1, 2, and 3 were bonded was compared with the light intensity of the organic EL element to which the film was not bonded. Table 2 shows the ratio of the light extraction efficiency obtained by dividing the light intensity of the organic EL element on which the film is bonded by the light intensity of the organic EL element on which the film is not bonded. The light intensity was measured when a current of 0.15 mA was passed through the organic EL element.

  The light extraction efficiency of the organic EL device of Production Example 1 was increased 1.5 times compared to before the film A was bonded. Further, the organic EL element of Preparation Example 2 in which the film A of Preparation Example 1 and the film B having optical properties close to each other was also increased in light extraction efficiency as in the case of the organic EL element of Preparation Example 1. However, since the surface of the film C used in the organic EL device of Comparative Example 1 was almost flat, no improvement in light extraction efficiency was observed. In Comparative Examples 2 and 3, no significant improvement in light extraction efficiency was observed.

  From this, it was revealed that a film having a high total light transmittance and a high haze value contributes to an improvement in light extraction efficiency. In particular, it was found that the light extraction efficiency is greatly improved when the haze value of the film is 70 or more. Thus, it was confirmed that the light extraction efficiency was improved by providing a film having predetermined optical characteristics.

1 Display Device 11 Drive Circuit 12 Switching Tr
13 Tr for driving
DESCRIPTION OF SYMBOLS 14 Capacitor 14a One flat plate 14b The other flat plate 15 Insulating layer 17 Planarizing film 19 Semiconductor layer SG Gate electrode SS Source electrode SD Drain electrode DG Gate electrode DS Source electrode DD Drain electrode 16, 18, 20a, 20b Through-hole wiring part DESCRIPTION OF SYMBOLS 21 Drive substrate 22 Substrate body 31 Organic EL element 32 1st electrode 33 2nd electrode 34 1 or several predetermined layer 41 Film 51 Partition

Claims (5)

A drive substrate exhibiting optical transparency on which a drive circuit exhibiting optical transparency is formed;
A plurality of organic electroluminescence elements that are provided on the driving substrate and are driven by the driving circuit to emit light toward the driving substrate;
A film disposed with the drive substrate interposed between the plurality of organic electroluminescence elements, and a display device having
The organic electroluminescence element is disposed at a position overlapping the drive circuit as viewed from one of the thickness directions of the drive substrate,
The film has a haze value of 70% or more and a total light transmittance of 50% or more, the surface opposite to the driving substrate side is uneven, and the uneven surface forms an interface with the atmosphere. A display device.   The drive circuit includes a light-transmitting wiring disposed at a position overlapping the organic electroluminescence element when viewed from one of the thickness directions of the drive substrate, and the wiring is made of an inorganic oxide conductor. The display device according to claim 1.   The drive circuit includes a transistor element exhibiting light transmittance disposed at a position overlapping the organic electroluminescence element when viewed from one of the thickness directions of the drive substrate, and the transistor element is a semiconductor layer made of an inorganic oxide semiconductor. The display device according to claim 2, further comprising: The inorganic oxide semiconductor and the inorganic oxide conductor are zinc tin oxide or indium-containing oxide, respectively.
The display device according to claim 3, wherein the semiconductor layer has a carrier concentration lower than that of the wiring.   The display according to claim 1, wherein the film is provided with a plurality of concave surfaces on a surface opposite to the drive substrate side, and the surface is formed in an uneven shape. apparatus.

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