JP4564897B2 - Electroluminescence element - Google Patents

Description

The present invention relates to an electroluminescence element .

  In recent years, a wet coating method such as an ink jet method has attracted attention as a method for producing a functional substrate such as a color filter substrate, an electroluminescence element (hereinafter abbreviated as “EL element”), and the like.

By using a wet coating method, a functional substrate and an EL element can be manufactured at low cost. However, for example, when a color filter substrate or an EL element is manufactured using a wet coating method, there is a problem in that pixel bleeding or color mixing between pixels is likely to occur. In view of such a problem, a technique for suppressing pixel bleeding and color mixing between pixels by providing a liquid-repellent partition (bank) between the pixels is disclosed (for example, Patent Document 1).
JP 7-35917 A

  However, when a liquid-repellent partition wall is provided between the pixels, there is a problem that the layer thickness unevenness of the functional layer tends to occur. Specifically, there is a problem that the layer thickness of the functional layer near the partition wall, that is, the peripheral thickness of the functional layer is thinner than the central layer.

The present invention has been made in view of, and has as its object to provide a E L elements that have a less functional layer having thickness unevenness.

The EL device according to the present invention includes a substrate, a liquid repellent partition, a photocatalyst layer containing titanium dioxide imparted with lyophilicity by i-line light, a functional layer, and a second electrode . A plurality of first electrodes are provided on the surface of the substrate. Septal wall between the Aitonaru first electrode of the substrate surface, are formed so as to partition the surface of the substrate into a plurality of regions. The photocatalyst layer is provided at least on the peripheral portion of each of the plurality of regions. The functional layer is formed in each of the plurality of regions so that the peripheral edge portion is in contact with the photocatalyst layer. The second electrode is provided on each of the functional layers.

  In this specification, “photocatalyst” expresses a property (lyophilicity) that is compatible with a functional layer forming ink used when forming a functional layer by a wet coating method by irradiating light. Refers to a catalyst that performs The photocatalyst itself is a substance that acts as a catalyst when irradiated with light. The catalyst is involved in the chemical reaction of other substances and affects the rate of the reaction. When light is irradiated to the photocatalyst, the surface structure of the photocatalyst changes, moisture in the air is adsorbed on the surface of the photocatalyst, and a thin water film is formed on the surface of the photocatalyst. As a result, it is generally known that a photocatalyst exhibits hydrophilicity when irradiated with light.

  The “wet coating method” refers to a method of forming a film using an ink in which a material for forming a functional layer is dissolved in a solvent (water, organic solvent, etc.). Specific examples include an inkjet method, a printing method, a spin coating method, a dip method, and a nozzle coating method.

  “Lipophilicity” refers to the property that the contact angle to the functional layer forming ink is 30 degrees or less (preferably 20 degrees or less). The “contact angle” can be measured with CA-W (Fully Automatic Contact Angle Meter) manufactured by Kyowa Interface Science Co., Ltd.

“Liquid repellency” refers to the property of repelling ink for forming a functional layer by a wet coating method. In particular, the ink is 30 degrees greater than the contact angle for forming the functional layer by a wet coating method (preferably at least 40 degrees of contact angle) will have the property of contact.

In addition , for example, even if a photocatalyst layer is not provided, a functional layer can be formed also in the peripheral part of each area | region by making the whole partition lyophilic. However, in this case, a large amount of the functional layer forming ink adheres to the lyophilic partition. For this reason, the layer thickness of the peripheral part of the functional layer becomes thick, and the layer thickness of the central part becomes thinner than the assumed value. Therefore, it becomes difficult to form a functional layer having a desired film thickness. As a result, a functional layer having a desired layer thickness and little film thickness unevenness cannot be realized.

The EL device according to the present invention has a photocatalyst layer provided at the peripheral portion of each region. This photocatalyst layer becomes lyophilic when irradiated with light (for example, ultraviolet light). For this reason, by irradiating the photocatalyst layer with light prior to the step of forming the functional layer by a wet coating method, the surface of the photocatalyst layer is kept lyophilic for a relatively long time in the functional layer formation step. be able to. Therefore, it is possible to effectively suppress the occurrence of layer thickness unevenness of the functional layer due to the liquid repellent partition (particularly, the peripheral portion of the functional layer becomes thin). That is, an EL device having a functional layer with a substantially uniform layer thickness according to the present invention can be easily produced by using a wet coating method.

In addition, since the photocatalyst layer contains titanium dioxide to which lyophilicity is imparted by i-line light, the photocatalyst layer can be made lyophilic using a general exposure machine. The photocatalyst can be activated.

In the EL device according to the present invention, adjacent regions are separated by a liquid repellent partition. For this reason, even if it is a case where it produces using wet coating methods, such as an inkjet method, the color mixture etc. between adjacent area | regions are suppressed.

In the EL device according to the present invention, the functional layer is a light emitting layer or a laminate of the light emitting layer and one or more buffer layers. Specifically, the buffer layer is a hole injection layer, a hole transport layer, an electron injection layer, or an electron transport layer. In other words, the functional layer may be composed of a light emitting layer and one or more layers in the group consisting of a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer.

Moreover, in the EL element according to the present invention, the peripheral portion of the photocatalyst layer is patterned in a comb shape. Accordingly, since the contact area between the first electrode and the functional layer can be increased, for example, when the functional layer is an organic layer having a light emitting layer, the light emitting area of the organic layer can be increased. As a result, a high-brightness EL element can be realized.

In the EL device according to the present invention, the photocatalyst layer is formed between the adjacent first electrodes on the surface of the substrate on the substrate so that both ends thereof are in contact with the adjacent first electrodes, and the partition walls are formed. The catalyst layer may be formed on the photocatalyst layer so that both ends of the catalyst layer are exposed.

In the EL device according to the present invention, the photocatalyst layer is preferably insulating. By doing so, current leakage between the first electrode and the second electrode can be effectively suppressed even when the functional layer is poorly coated.

In the EL device according to the present invention, the layer thickness of the photocatalyst layer is preferably 20 nm or more.

  By setting the layer thickness of the photocatalyst layer to 20 nm or more, the layer thickness unevenness of the functional layer can be more effectively suppressed. In addition, the layer thickness of the photocatalyst layer means the average layer thickness of the peripheral portion in contact with the functional layer.

The EL element according to the present invention preferably further includes an insulating layer provided between the photocatalytic layer and the substrate. The insulating layer may consist essentially of silicon dioxide.

Insulating layer between the photocatalyst layer and the substrate (e.g., silicon dioxide (SiO ₂₎ layer) by further providing, it is possible to improve the catalytic activity of the photocatalyst layer (lyophilic). Therefore, Ru can be more effectively suppressed thickness unevenness of the functional layer.

As described on the following, according to the present invention, it is possible to realize an EL device having a low functional layer having thickness unevenness. In addition, the photocatalyst can be activated easily and inexpensively. In addition, a high-brightness EL element can be realized.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  (Embodiment 1) FIG. 1 is a sectional view of an organic EL element 1 according to Embodiment 1. In FIG.

  FIG. 2 is a plan view of the organic EL element 1. For convenience of explanation, the upper common electrode 50 and the sealing substrate 60 are not drawn in FIG.

  The organic EL element 1 includes an organic electroluminescence substrate (hereinafter abbreviated as “organic EL substrate”) 2 and a sealing substrate 60. The organic EL substrate 2 includes an active matrix substrate (hereinafter abbreviated as “AM substrate”) 10, a bank (partition wall) 30, an organic layer 40 as a functional layer, and an upper common electrode 50 as a second electrode. .

  The AM substrate 10 includes a substrate body 11, switching elements 12 arranged in a matrix on the substrate body 11, a planarizing film 13 formed on the switching elements 12, and a matrix on the planarizing film 13. And a pixel electrode 14 as a first electrode. The switching element 12 and the pixel electrode 14 are electrically connected via a through hole provided in the planarizing film 13.

The substrate body 11 has a function of ensuring the mechanical durability of the organic EL element 1 and a function of suppressing moisture and oxygen from entering the organic layer 40 and the like from the outside. The substrate body 11 may be a glass substrate, a quartz substrate, a plastic substrate such as polyethylene terephthalate, or the like. And a substrate formed of an insulating material such as ceramics such as alumina. The substrate body 11 is a substrate in which one side of a metal substrate made of aluminum, iron, or the like is coated with an insulating material such as SiO ₂ or an organic insulating material, and the surface of the metal substrate is subjected to insulation treatment by a method such as anodization. It may be a substrate or the like. In addition, when the organic EL element 1 is a bottom emission system in which light is emitted from the substrate body 11 side, the substrate body 11 is preferably made of a material having high light transmittance such as glass or plastic.

  The switching element 12 can be configured by, for example, a thin film transistor (TFT), a MIM (Metal-Insulator-Metal) diode, or the like.

  The planarizing film 13 planarizes one surface of the AM substrate 10 (surface on the pixel electrode 14 side). The planarizing film 13 can be formed of an acrylic resin, a novolac resin, a polyimide resin, or a mixed resin thereof.

The pixel electrode 14 injects holes into the organic layer 40. The material of the pixel electrode 14 is silver (Ag), aluminum (Al), vanadium (V), cobalt (Co), nickel (Ni), tungsten (W), gold (Au), calcium (Ca), titanium ( Ti), yttrium (Y), sodium (Na), ruthenium (Ru), manganese (Mn), indium (In), magnesium (Mg), lithium (Li), ytterbium (Yb), lithium fluoride (LiF), etc. And conductive oxides such as tin oxide (SnO), zinc oxide (ZnO), indium tin oxide (ITO), and indium zinc oxide (IZO). The pixel electrode 14 includes magnesium (Mg) / copper (Cu), magnesium (Mg) / silver (Ag), sodium (Na) / potassium (K), astatine (At) / oxidized astatine (AtO ₂ ), lithium (Li ) / Aluminum (Al), lithium (Li) / calcium (Ca) / aluminum (Al), or an alloy such as lithium fluoride (LiF) / calcium (Ca) / aluminum (Al).

  From the viewpoint of increasing the hole injection rate of the pixel electrode 14, among the materials of the pixel electrode 14 described above, a material having a large work function is more preferable. Examples of the material having a large work function include indium tin oxide (ITO) and indium zinc oxide (IZO).

  Further, when the organic EL element 1 is a bottom emission method in which light from the organic layer 40 is extracted from the AM substrate 10 side, the pixel electrode 14 is formed of a light transmissive material such as indium tin oxide (ITO). Preferably it is. According to this configuration, the absorption rate of the light from the organic layer 40 by the pixel electrode 14 can be reduced, and high luminance can be realized.

  On the other hand, when the organic EL element 1 is a top emission method in which the light emission of the organic layer 40 is extracted from the upper common electrode 50 side, the pixel electrode 14 is preferably formed of a light reflective material such as aluminum (Al). . According to this configuration, light emitted from the organic layer 40 toward the pixel electrode 14 is reflected by the pixel electrode 14 toward the upper common electrode 50 with a high reflectance. For this reason, since the emitted light rate of the light from the organic layer 40 can be made high, high brightness | luminance is realizable.

  The layer thickness of the pixel electrode 14 is preferably 50 nm or more and 500 nm or less. If it is smaller than 50 nm, it is difficult to obtain a desired film strength. In addition, it becomes difficult to obtain a desired resistance value. If it is larger than 500 nm, there is a tendency that the possibility that the pixel electrode 14 is peeled off increases.

  In the organic EL element 1 according to this embodiment, the pixel electrode 14 is formed in a substantially rectangular shape, but the pixel electrode 14 may be circular, elliptical, or the like.

  The pixel electrode 14 may be subjected to a lyophilic process. In the case where the organic layer 40 is formed on the pixel electrode 14 by a wet coating method (inkjet method or the like), the affinity between the pixel electrode 14 and the organic layer 40 is obtained by performing a lyophilic process on the pixel electrode 14. This is because the organic layer 40 having a more uniform layer thickness can be formed.

  Between adjacent pixel electrodes (first electrodes) 14 on the surface of the AM substrate 10, a liquid-repellent bank 30 having a substantially trapezoidal cross section formed in a lattice shape is provided. The bank 30 is provided so as to partition the surface of the AM substrate 10 into a plurality of regions. As shown in FIG. 2, in the first embodiment, the regions partitioned by the banks 30 formed in a lattice shape are substantially rectangular. In addition, a substantially rectangular shape means a rectangle or a rectangle whose corners are obtuse. Here, making the corner part obtuse means that the corner part is constituted by an angle (a plurality of angles) exceeding 90 degrees or a curve. You may comprise a corner | angular part with the combination of a curve and an obtuse angle.

  The bank 30 can be formed of polyimide resin, acrylic resin, novolac resin, or the like. You may form with the material which mixed these resin. Polyimide resins, acrylic resins, and novolak resins have high heat resistance (thermal stability) among organic materials, and are not easily degassed, discolored, altered, deformed, or the like. Therefore, the stability of the bank 30 portion can be improved by forming the bank 30 using one type or two or more types of resins selected from the group consisting of polyimide resin, acrylic resin, and novolac resin. The organic EL element 1 having a long product life can be realized.

Further, the bank 30 may have a two-layer structure. Specifically, the lower layer of the bank _{30 SiO 2, Si 3 N 4} , an inorganic insulating layer such as SiO _N may be further formed. By doing so, it becomes possible to more effectively suppress leakage current and dielectric breakdown.

  The surface of the bank 30 is preferably at least liquid repellent. By making the surface liquid-repellent, color mixing of adjacent organic layers 40 can be effectively suppressed. As a method of manufacturing the bank 30 having a liquid repellent surface, a method of forming the bank 30 with a liquid repellent material, a method of adding an additive having a liquid repellent property to the bank 30, and a repellent property of the bank 30 part. Examples include a method for performing liquefaction treatment.

  Examples of the additive having liquid repellency include a fluorine-based additive and a silica-based additive. Specifically, examples of the fluorine-based additive include calcium fluoride, sodium hexafluoride aluminum, sodium fluoride, sodium monofluorophosphate, and fluoroethylene. Examples of the silica-based additive include polysilazane and tetraethoxysilane.

  Examples of the material having liquid repellency include a polyimide resin in which a methyl group or a fluorine group is introduced into the side chain.

  The photocatalyst layer 20 is provided at least at each peripheral portion of each region partitioned by the bank 30. Specifically, the photocatalytic layer 20 is provided between the bank 30 and the pixel electrode 14. More specifically, the photocatalytic layer 20 extends between adjacent pixel electrodes 14 on the surface of the AM substrate 10 so that both ends are in contact with the adjacent pixel electrodes 14 (preferably, both ends are adjacent to each other). The pixel electrode 14 is overlapped with the end of the pixel electrode 14. The photocatalytic layer 20 isolates the liquid repellent bank 30 from the surface of the AM substrate 10.

The photocatalyst layer 20 contains a photocatalyst. Examples of the photocatalyst include titanium dioxide (TiO ₂ ), zinc oxide (ZnO), barium titanate (BaTiO ₃ ), strontium titanate (SrTiO ₃ ), calcium titanate (CaTiO ₃ ), and potassium tantalate (KTaO ₃ ). , Tin dioxide (SnO ₂ ), zircon dioxide (ZrO ₂ ), and the like. The photocatalyst layer 20 may contain one or more of these photocatalysts. Moreover, you may form only with these photocatalysts. Among these photocatalysts, for example, a photocatalyst that exhibits lyophilicity by i-line (365 nm) light is particularly preferable. The i-line (365 nm) light is also used in, for example, a photolithography exposure machine, and the photocatalyst layer 20 can be made lyophilic using a general exposure machine. Can be activated.

  The photocatalyst layer 20 is preferably insulative. By making the photocatalyst layer 20 insulative, for example, current leakage between the pixel electrode 14 and the upper common electrode 50 is effective even when the organic layer 40 (particularly, the light emitting layer 42) is poorly coated. Can be suppressed. From the viewpoint of more effectively suppressing current leakage, the layer thickness of the photocatalyst layer 20 is preferably 20 nm or more.

  In the first embodiment, the photocatalyst layer 20 is formed between adjacent pixel electrodes 14 so that both ends thereof are in contact with the adjacent pixel electrodes 14. However, the present invention is not limited to this configuration. For example, as shown in FIGS. 3 and 4, a photocatalytic layer 20 may be provided.

  3 and 4 are cross-sectional views illustrating examples of the formation of the photocatalyst layer 20.

  As shown in FIG. 3, the photocatalyst layer 20 may be provided only in the peripheral portion of each region (only in the vicinity of the contact portion between the bank 30 and the pixel electrode 14). As shown in FIG. 4, the photocatalytic layer 20 may be provided under the bank 30 so as to be substantially trapezoidal with the bank 30.

  Further, as shown in FIG. 5, the peripheral portion of the photocatalyst layer 20 may be patterned in a comb shape.

  FIG. 5 is a partial plan view showing a case where the peripheral portion of the photocatalyst layer 20 is patterned in a comb shape. For convenience of explanation, the sealing substrate 60, the upper common electrode 50, and the organic layer 40 are not drawn in FIG.

  As shown in FIG. 5, the contact area between the pixel electrode 14 and the organic layer 40 can be increased by patterning the peripheral portion of the photocatalyst layer 20 in a comb shape. For this reason, the light emission area of the organic layer 40 can be increased. Therefore, a high-brightness organic EL element 1 can be realized.

  The organic layer 40 is formed so that the peripheral portion is in contact with the photocatalyst layer 20. The organic layer 40 has a hole transport layer 41 and a light emitting layer 42. However, the present invention is not limited to this configuration, and the organic layer 40 may be configured by only the light emitting layer 42. Alternatively, the organic layer 40 may be a stack of the light emitting layer 42 and a buffer layer such as a hole injection layer, a hole transport layer 41, an electron transport layer, or an electron injection layer.

  The hole transport layer 41 improves the hole transport efficiency from the pixel electrode 14 to the light emitting layer 42. Examples of the hole transport material for forming the hole transport layer 41 include porphyrin derivatives, aromatic tertiary amine compounds, styrylamine derivatives, polyvinylcarbazole, poly-p-phenylene vinylene, polysilane, triazole derivatives, oxadiazole derivatives, Imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amine-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, hydrogenated amorphous silicon, hydrogenated Examples thereof include amorphous silicon carbide, zinc sulfide, and zinc selenide.

  The light emitting layer 42 emits light by recombining holes injected from the pixel electrode 14 and electrons injected from the upper common electrode 50.

  As a light emitting material for forming the light emitting layer 42, metal oxinoid compound [8-hydroxyquinoline metal complex], naphthalene derivative, anthracene derivative, diphenylethylene derivative, vinylacetone derivative, triphenylamine derivative, butadiene derivative, coumarin derivative, Benzoxazole derivatives, oxadiazole derivatives, oxazole derivatives, benzimidazole derivatives, thiadiazole derivatives, benzthiazole derivatives, styryl derivatives, styrylamine derivatives, bisstyrylbenzene derivatives, tristyrylbenzene derivatives, perylene derivatives, perinone derivatives, aminopyrene derivatives, pyridine Derivatives, rhodamine derivatives, acuidine derivatives, phenoxazone, quinacridone derivatives, rubrene, poly-p-phenylene vinylene, Rishiran, and the like.

  The upper common electrode 50 is formed so as to cover the entire bank 30 and the plurality of organic layers 40. The upper common electrode 50 injects electrons into the organic layer 40.

As the material of the upper common electrode 50, silver (Ag), aluminum (Al), vanadium (V), cobalt (Co), nickel (Ni), tungsten (W), gold (Au), calcium (Ca), titanium (Ti), yttrium (Y), sodium (Na), ruthenium (Ru), manganese (Mn), indium (In), magnesium (Mg), lithium (Li), ytterbium (Yb), lithium fluoride (LiF) Or metal oxides such as tin oxide (SnO), zinc oxide (ZnO), or conductive oxides such as indium tin oxide (ITO) and indium zinc oxide (IZO). The upper common electrode 50 includes magnesium (Mg) / copper (Cu), magnesium (Mg) / silver (Ag), sodium (Na) / potassium (K), astatine (At) / oxidized astatine (AtO ₂ ), lithium (Li ) / Aluminum (Al), lithium (Li) / calcium (Ca) / aluminum (Al), or an alloy such as lithium fluoride (LiF) / calcium (Ca) / aluminum (Al).

  Among these materials, a material having a small work function is more preferable. This is because the electron injection efficiency into the organic layer 40 can be improved by forming the upper common electrode 50 with a material having a small work function. Materials having a low work function include magnesium (Mg), lithium (Li), lithium fluoride (LiF), magnesium (Mg) / copper (Cu), magnesium (Mg) / silver (Ag), sodium (Na) / Examples include potassium (K), lithium (Li) / aluminum (Al), lithium (Li) / calcium (Ca) / aluminum (Al), or lithium fluoride (LiF) / calcium (Ca) / aluminum (Al). It is done.

  Further, when the organic EL element 1 is a top emission type in which the light of the light emitting layer 42 is extracted from the upper common electrode 50 side, the upper common electrode 50 is formed of a light transmissive material such as indium tin oxide (ITO). It is preferable. According to this configuration, since the absorption rate of the light from the light emitting layer 42 by the upper common electrode 50 can be lowered, the organic EL element 1 having high luminance can be realized.

  On the other hand, when the organic EL element 1 is a bottom emission method in which light from the light emitting layer 42 is extracted from the AM substrate 10 side, the upper common electrode 50 is preferably formed of a light reflective material such as aluminum (Al). . According to this configuration, light emitted from the light emitting layer 42 toward the upper common electrode 50 side is reflected by the upper common electrode 50 toward the pixel electrode 14 side with a high reflectance. Therefore, since the light emission rate of light from the light emitting layer 42 can be increased, the organic EL element 1 having high luminance can be realized.

  A sealing substrate 60 is provided on the upper common electrode 50. The sealing substrate 60 is bonded and fixed to the AM substrate 10 with a sealing material at the peripheral portion. By providing the sealing substrate 60, it is possible to effectively prevent moisture and oxygen from entering the element. For this reason, the organic EL element 1 having a long lifetime can be realized.

  The sealing substrate 60 can be composed of a glass substrate, a quartz substrate, or the like. As the sealing material for bonding the sealing substrate 60, an adhesive having low oxygen permeability and moisture permeability such as epoxy resin is preferable.

  Moreover, you may provide a desiccant inside the sealing substrate 60 from a viewpoint of implement | achieving a longer lifetime.

  Hereinafter, the manufacturing method of the organic EL element 1 will be described in detail with reference to the drawings.

  6 to 10 are cross-sectional views illustrating manufacturing steps of the organic EL element 1.

  FIG. 6 is a cross-sectional view illustrating a process of forming the photocatalytic layer 20 on the AM substrate 10.

  First, the photocatalytic layer 20 is formed on the AM substrate 10. The photocatalyst layer 20 can be formed by, for example, a lift-off method. Specifically, a photoresist was applied by spin coating or the like, and a desired pattern was exposed using a photomask. A resist pattern is formed by developing with a developer and then washing with water. For example, a material containing a photocatalyst is formed on the formed resist pattern using a high-frequency magnetron sputtering apparatus or the like. Thereafter, the photocatalyst layer 20 can be formed by immersing in a stripping solution and subsequently rinsing the photoresist to remove the photoresist.

  A bank 30 is formed on the photocatalyst layer 20. Specifically, for example, a polyimide resin or the like is formed by spin coating. Thereafter, the bank 30 can be formed by photo-patterning the obtained thin film.

The AM substrate 10 on which the bank 30 is formed is subjected to a lyophilic process to impart lyophilicity to the pixel electrode 14. Examples of the lyophilic treatment include UV / O ₃ treatment. Further, liquid repellency is imparted to the bank 30 by performing a liquid repellency treatment. An example of the liquid repellency treatment is CF ₄ plasma treatment. Thus, by making the pixel electrode 14 lyophilic and making the bank 30 lyophobic, the uniformity of the layer thickness of the organic layer 40 to be formed later by a wet coating method can be improved. Specifically, since the ink for forming the organic layer 40 has a relatively high affinity for the pixel electrode 14, the ink tends to spread over the entire surface of the pixel electrode 14. For this reason, it becomes easy to form the organic layer 40 in the peripheral part of each area | region. In addition, it is possible to suppress a large amount of ink for forming the organic layer 40 from adhering to the bank 30. For this reason, it can suppress that the peripheral part of the organic layer 40 becomes thick with respect to a center part.

In the case of applying the CF ₄ plasma treatment, so as not to damage the bank 30, it is preferred to treat small output in a short time. The treatment time is preferably between 20 seconds and 30 minutes, and can be appropriately determined depending on the material of the bank 30. The output is preferably in the range of 10 to 1000 W / m ² . Further, when an additive having liquid repellency is added to the bank 30, when the bank 30 is formed of a material having liquid repellency, it is not necessary to perform the liquid repellency treatment of the bank 30.

  FIG. 7 is a cross-sectional view showing a process of making the photocatalyst layer 20 lyophilic.

  After forming the bank 30, the surface of the photocatalyst layer 20 is made lyophilic by irradiating light (for example, near ultraviolet light, ultraviolet light, etc.) from the bank 30 side. By doing in this way, the organic layer 40 formed later with the wet application method is suitably formed also in the peripheral part of each area | region. For this reason, the organic layer 40 with high uniformity can be formed. In addition, the wavelength of the light to irradiate can be suitably determined according to the photocatalyst to be used.

  The photocatalyst layer 20 is preferably irradiated with light in an atmosphere having a moisture concentration of 10% or more. By doing so, the photocatalyst layer 20 having high activity (in other words, high lyophilicity) can be realized.

  FIG. 8 is a cross-sectional view illustrating a process of forming the hole transport layer 41 by a wet coating method.

  A hole transport layer 41 is formed in each of a plurality of regions partitioned by the bank 30 by a wet coating method (for example, an ink jet method). Specifically, a hole transport layer forming ink is prepared by first dissolving a hole transport material in a solvent. The concentration of the ink can be 5% by weight, for example.

  Solvents that can be used for ink preparation include toluene, o-xylene, m-xylene, p-xylene, ethylbenzene, hemimeritene [1,2,3-trimethylbenzene], pseudocumene [1,2,4-trimethylbenzene]. Mesitylene [1,3,5-trimethylbenzene], cumene [isopropylbenzene], planitene [1,2,3,4-tetramethylbenzene], isodurene [1,2,3,5-tetramethylbenzene], durene [1,2,4,5-tetramethylbenzene], p-cymene [isopropyltoluene], tetralin [1,2,3,4-tetrahydronaphthalene], cyclohexylbenzene, melitene [hexamethylbenzene], methanol, ethanol, 1-propanol, 2-propanol [IPA; isopropyl Alcohol], ethylene glycol [1,2-ethanediol], diethylene glycol, 2-methoxyethanol [ethylene glycol monomethyl ether, methyl cellosolve], 2-ethoxyethanol [ethylene glycol monoethyl ether, cellosolve], 2- (methoxymethoxy) Ethanol, 2-isopropoxyethanol, 2-butoxyethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, glycerin, acetone, N-methyl-2-pyrrolidone, 1,3-dimethyl- Examples include 2-imidazolidinone, anisole [methoxybenzene], and water. A mixture of these solvents may be used.

  Next, the hole transport layer 41 is formed by applying the prepared ink to each region and drying at 100 ° C. to 250 ° C. for about 0.5 minutes to 120 minutes.

  As described above, the pixel electrode 14 and the photocatalyst layer 20 are lyophilic with respect to the hole transport layer forming ink, and the bank 30 is lyophobic. For this reason, it is possible to suppress a large amount of the hole transport layer forming ink from adhering to the bank 30. Further, the hole transport layer 41 can be formed with a substantially uniform layer thickness in every corner of each region.

  FIG. 11 is a cross-sectional view illustrating a process of forming a hole transport layer by a wet coating method when the photocatalyst layer 20 is not provided.

  As shown in FIG. 11, when the photocatalyst layer 20 is not provided, the hole transport layer forming ink is not applied to every corner of each region due to the liquid repellency of the bank 30. For this reason, it becomes difficult to form the hole transport layer 41 with high uniformity.

  FIG. 9 is a cross-sectional view illustrating a process of forming the light emitting layer 42 by a wet coating method.

  A light emitting layer 42 is formed on each of the hole transport layers 41 by a wet coating method. Since the hole transport layer 41 is generally lyophilic with respect to the ink for forming the light emitting layer, the light emitting layer 42 can be formed with a substantially uniform layer thickness as with the hole transport layer 41. .

  In this manner, the hole transport layer 41 and the light emitting layer 42 can be formed with high uniformity up to the peripheral portion of each region. In other words, high coverage of the hole transport layer 41 and the light emitting layer 42 can be realized. For this reason, current leakage between the pixel electrode 14 and the upper common electrode 50 can be effectively realized.

  FIG. 10 is a cross-sectional view illustrating a process of forming the upper common electrode 50.

  The upper common electrode 50 can be formed by, for example, sputtering or vapor deposition.

  After the formation of the upper common electrode 50, the sealing substrate 60 made of glass or the like is bonded and fixed to the AM substrate 10 with a sealing material, whereby the organic EL element 1 shown in FIGS. 1 and 2 can be completed. The step of sealing the sealing substrate 60 is preferably performed in an inert gas (nitrogen, argon, etc.) atmosphere.

  (Embodiment 2) FIG. 12 is a sectional view of an organic EL element 3 according to Embodiment 2. In FIG.

  The organic EL element 3 according to the second embodiment is an organic EL element according to the first embodiment in that an insulating layer 70 formed so as to be stacked on the photocatalyst layer 20 is provided between the photocatalyst layer 20 and the AM substrate 10. Different from EL element 1. Here, description will be given focusing on the insulating layer 70.

  In the second embodiment, components having substantially the same functions as those in the first embodiment are commonly described with reference numerals, and description thereof is omitted.

  In the organic EL element 3 according to the second embodiment, the insulating layer 70 is provided between the adjacent pixel electrodes 14 so that both ends thereof are in contact with the adjacent pixel electrodes 14. And the photocatalyst layer 20 is provided so that the surface of the insulating layer 70 may be covered.

  Thus, the catalytic activity of the photocatalyst layer 20 can be improved by providing the insulating layer 70 so as to be in contact with the photocatalyst layer 20. In other words, the lyophilicity of the photocatalyst layer 20 can be improved.

The insulating layer 70 can be formed of, for example, silicon dioxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), silicon oxynitride film (SiON), or the like. In particular, when titanium dioxide (TiO ₂ ) is used as a photocatalyst, it is preferable to form a silicon dioxide layer as the insulating layer 70. By combining silicon dioxide and titanium dioxide, the lyophilicity of the photocatalytic layer 20 can be improved more effectively.

  The application examples of the present invention have been described above by taking the active matrix type organic EL elements 1 and 2 as examples. However, the present invention is not limited thereto. The present invention is also applied to, for example, a passive matrix organic EL element. Also generally used for functional substrates represented by color filter substrates, circuit substrates having conductive layers as functional layers, organic thin film transistor substrates having organic semiconductor layers as functional layers, microlens array substrates having lens layers as functional layers, etc. Applicable.

  As an example and a comparative example, the layer thickness of the photocatalyst layer 20 was changed variously, and the organic EL element of the same form as the organic EL element 1 demonstrated in Embodiment 1 was produced and evaluated.

First, an AM substrate 10 in which pixel electrodes 14 made of indium tin oxide (ITO) were formed in a matrix was prepared. A photocatalyst layer 20 was formed on the AM substrate 10 by forming and patterning a titanium dioxide (TiO ₂ ) film using a lift-off method. The film forming conditions were a Ti target, an Ar / O ₂ gas partial pressure ratio of 50:50, and a gas pressure of 2 Pa.

  A polyimide resin film was formed on the photocatalyst layer 20 by spin coating, and a bank 30 was formed by photo-patterning.

The AM substrate 10 on which the bank 30 was formed was subjected to UV / O ₃ treatment to impart lyophilicity to the pixel electrode 14. Further, liquid repellency was imparted to the bank 30 by performing CF ₄ plasma treatment.

  After forming the bank 30, the surface of the photocatalyst layer 20 was made lyophilic by irradiating light (wavelength 365 nm) for 10 minutes from the bank 30 side.

A hole transport layer 41 was formed in each of a plurality of regions partitioned by the bank 30 by an inkjet method. Polythiophene and polymer acid were used as the hole transport material. Xylene was used as the solvent. The concentration of the prepared ink was 5% by weight. The ink dripping amount was 0.01 L / m ² . After the ink was dropped, the hole transport layer 41 was formed by baking at 200 ° C. for 10 minutes.

A light emitting layer 42 was formed on each of the hole transport layers 41 by a wet coating method. A PPV derivative << poly {2,5-bishexyloxy-1,4-phenylene- (1-cyanovinylene)}} was used as a luminescent material, and xylene was used as a solvent. The concentration of the prepared ink was 5% by weight. The ink dripping amount was 0.01 L / m ² . After the ink was dropped, the hole transport layer 41 was formed by baking at 200 ° C. for 10 minutes.

  Next, an upper common electrode 50 was formed by forming a stack of an aluminum layer having a layer thickness of 100 nm and a calcium layer having a layer thickness of 5 nm by using an evaporation method.

  Finally, as a sealing substrate 60, an organic EL device according to Examples and Comparative Examples was completed by bonding and fixing a glass substrate with an epoxy resin in a nitrogen atmosphere.

  As examples, an organic EL element having a photocatalyst layer 20 having a thickness of 20 nm, an organic EL element having a thickness of 50 nm, and an organic EL element having a thickness of 100 nm were produced. As a comparative example, an organic EL element having a photocatalyst layer 20 having a thickness of 10 nm was produced.

The presence or absence of current leakage and device pressure resistance of these organic EL devices were evaluated. The presence or absence of current leakage is present when a reverse bias voltage (a negative voltage is applied to the pixel electrode 14 and a positive DC voltage is applied to the upper common electrode 50) is applied to the element when the current flows more than 0.01 mA / cm ^2. (×). On the other hand, it was determined that there was no leakage current when the current was 0.01 mA / cm ² or less (◯). The element withstand voltage (V) is 10A instantaneously applied by applying a forward bias voltage (a positive voltage to the pixel electrode 14 and a negative voltage to the upper common electrode 50) to the organic EL element slowly from 0V to 20V. It was measured by monitoring the voltage value when flowing at / cm ² or more. When the element pressure resistance (V) was less than 15V, it was judged as defective, and when it was 15V or more, it was judged as good. The results are shown in Table 1 below.

As shown in Table 1, it was found that when the layer thickness of the photocatalyst layer 20 was 20 nm or more, there was no current leakage and an organic EL device having excellent device pressure resistance was obtained.
When the layer thickness of the photocatalyst layer 20 is thinner than 20 nm, the probability of occurrence of current leakage increases and the device pressure resistance tends to decrease.

As described above, since the EL element according to the present invention has a functional layer with little layer thickness unevenness, it is useful as a member of a display device such as a liquid crystal display device or an organic / inorganic EL display device.

1 is a cross-sectional view of an organic EL element 1 according to Embodiment 1. FIG. 1 is a plan view of an organic EL element 1. FIG. 3 is a cross-sectional view illustrating a formation example of a photocatalyst layer 20. FIG. 3 is a cross-sectional view illustrating a formation example of a photocatalyst layer 20. FIG. It is a fragmentary top view showing the case where the peripheral part of the photocatalyst layer 20 is patterned in a comb-tooth shape. 3 is a cross-sectional view illustrating a process of forming a photocatalytic layer 20 on the AM substrate 10. FIG. It is sectional drawing showing the process of making the photocatalyst layer 20 lyophilic. It is sectional drawing showing the process of forming the light emitting layer 42 by the wet apply | coating method. It is sectional drawing showing the process of forming the light emitting layer 42 by the wet apply | coating method. 5 is a cross-sectional view illustrating a process of forming an upper common electrode 50. FIG. It is sectional drawing showing the process of forming a hole transport layer by the wet apply | coating method when not providing the photocatalyst layer. 5 is a cross-sectional view of an organic EL element 3 according to Embodiment 2. FIG.

1, 3 Organic EL elements
2 Organic EL substrate
10 AM substrate
11 Board body
12 Switching element
13 Planarization film
14 Pixel electrode
20 Photocatalyst layer
30 banks
40 Organic layer
41 hole transport layer
42 Light emitting layer
50 Upper common electrode
60 sealing substrate
70 Insulating layer

Claims (6)

A substrate having a plurality of first electrodes provided on the surface ;
A liquid-repellent partition wall formed between adjacent first electrodes on the substrate surface and partitioning the surface of the substrate into a plurality of regions;
A photocatalyst layer containing titanium dioxide provided at least in the peripheral portion of each of the plurality of regions, and having lyophilic properties imparted by i-line light;
In each of the plurality of regions, a functional layer formed so that a peripheral portion is in contact with the photocatalyst layer;
A second electrode provided on each of the functional layers;
An electroluminescent device comprising:
An electroluminescence element in which a peripheral portion of the photocatalyst layer is patterned in a comb shape. In electroluminescent device of claim 1,
The photocatalytic layer is formed between the first electrodes adjacent to each other on the substrate surface on the substrate so that both ends thereof are in contact with the adjacent first electrodes,
The partition is an electroluminescence element provided on the photocatalyst layer such that the both ends of the photocatalyst layer are exposed. The electroluminescent device according to claim 1,
An electroluminescence device in which the photocatalyst layer is insulating. The electroluminescent device according to claim 3,
An electroluminescence device wherein the photocatalyst layer has a thickness of 20 nm or more. The electroluminescent device according to claim 1,
An electroluminescence device further comprising an insulating layer formed so as to be laminated on the photocatalyst layer between the photocatalyst layer and the substrate. The electroluminescent device according to claim 5,
The insulating layer is an electroluminescence element substantially made of silicon dioxide.

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