JP2010192117A - Organic electroluminescent element, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL element having a high light extraction efficiency, and to provide a lighting device, a planar light source and a display device using the organic EL element. <P>SOLUTION: The organic EL element includes a transparent first electrode, a second electrode with different polarity to the first electrode, a luminous layer arranged between the first and the second electrodes, a transparent substrate arranged on the opposite side to the luminous layer side of the first electrode, and a film arranged on the opposite side to the luminous layer side of the transparent substrate. When the refractive index of the first electrode is denoted by n1 and the refractive index of the transparent substrate is denoted by n2, the n1 and n2 respectively satisfy the formula (1), the surface on the opposite side to the transparent substrate side of the film is formed in concavo-convex shape, the haze value of the film is 70% or more, and the total light transmittance of the film is 80% or more. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an organic electroluminescence element and a method for manufacturing the same, and an illumination device, a planar light source, and a display device using the organic electroluminescence element.

An organic electroluminescence element (hereinafter sometimes referred to as an organic EL element) includes a pair of electrodes and a light emitting layer disposed between the electrodes.
The organic EL element emits light when a voltage is applied. When a voltage is applied between the electrodes, holes are injected from the anode and electrons are injected from the cathode. Holes and electrons injected into the element move to the light emitting layer and emit light when they are combined. A transparent electrode is used as one of the pair of electrodes, and light emitted from the light emitting layer is emitted outside the element through the transparent electrode. In this way, the light generated inside the element is extracted outside the element. For such a transparent electrode, a thin film made of indium tin oxide (ITO) is generally used.

The organic EL element is usually mounted on a substrate such as a glass plate. In the organic EL element in which the transparent electrode of the pair of electrodes is disposed near the substrate, light generated inside the element is taken out of the element through the transparent electrode and the support substrate. However, since the light generated inside the element is reflected by the transparent electrode and the substrate or absorbed inside, a part of the light is currently taken out and used only.
When the light extraction efficiency is low, most of the light generated inside the device is not used, resulting in a decrease in light emission efficiency. Therefore, for the purpose of improving the light extraction efficiency, an organic EL element in which a light scattering layer is provided between a transparent electrode and a substrate has been proposed (see, for example, Patent Document 1).

  However, the organic EL element of the above conventional technique does not necessarily have sufficient light extraction efficiency, and further improvement in light extraction efficiency is required.

JP 2007-035550 A

  The present invention has been made in view of the above-described problems of the prior art, and the problem is that an organic EL element with high light extraction efficiency and a manufacturing method thereof, an illumination device using the organic EL element, a planar light source, and It is to provide a display device.

  In order to solve the above-described problems, the present invention provides an organic EL element adopting the following configuration, a manufacturing method thereof, an illumination device, a planar light source, and a display device using the organic EL element.

[1] A transparent first electrode, a second electrode having a different polarity from the first electrode, a light emitting layer disposed between the first and second electrodes, and the light emitting layer side of the first electrode A transparent substrate disposed on the opposite side of the transparent substrate, and a film disposed on the opposite side of the transparent substrate to the light emitting layer side, wherein the refractive index of the first electrode is n1, and the refractive index of the transparent substrate Is n2, n1 and n2 are respectively represented by the following formulas (1)

を満たし、
前記フィルムの前記透明基板側とは反対側の表面が凹凸状に形成され、該フィルムのヘイズ値が７０％以上であり、かつ該フィルムの全光線透過率が８０％以上である有機エレクトロルミネッセンス素子。

The filling,
An organic electroluminescence device in which the surface of the film opposite to the transparent substrate is formed in an uneven shape, the haze value of the film is 70% or more, and the total light transmittance of the film is 80% or more .

[2] The organic electroluminescent element according to the above [1], wherein the first electrode is formed by a coating method.

[3] The organic electroluminescent element according to the above [1] or [2], wherein the first electrode includes a transparent film body and a wire-like conductor disposed in the film body.

[4] The organic electroluminescent element according to the above [3], wherein the wire-like conductor has a diameter of 200 nm or less.

[5] The organic electroluminescence element according to the above [4], wherein the wire-like conductor forms a network structure in the film main body.

[6] The organic electroluminescent element according to any one of [3] to [5], wherein the film main body includes a resin having conductivity.

[7] The surface on the opposite side to the transparent substrate side of the film is formed into the uneven shape by arranging a plurality of concave surfaces, and any one of the above [1] to [6] The organic electroluminescent element of description.

[8] An organic electroluminescence device for producing the organic electroluminescence device according to any one of the above [1] to [7] by providing a first electrode, a second electrode, a light emitting layer, a transparent substrate, and a film. In the method of providing the film, in the step of providing the film, a solution containing the material to be the film is applied on the surface of a predetermined base so that the thickness of the film is in a range of 100 μm to 200 μm. The manufacturing method of the organic electroluminescent element which obtains the said film by hold | maintaining the solution apply | coated on the surface of the said base in 80%-90% of humidity, and evaporating the solvent in a solution.

[9] An illumination device including the organic electroluminescence element according to any one of [1] to [7].

[10] A planar light source comprising the organic electroluminescence element according to any one of [1] to [7].

[11] A display device comprising the organic electroluminescence element according to any one of [1] to [7].

  In this specification, “transparent substrate” and “transparent electrode” mean a substrate or an electrode through which at least part of incident light is transmitted.

  In the organic EL device of the present invention, when the refractive index of the first electrode is n1 and the refractive index of the transparent substrate is n2, n1 and n2 are respectively represented by the following formula (1):

を満たし、前記透明基板の光取出し側の表面部にフィルムが設けられ、該フィルムの前記透明基板側とは反対側の表面が凹凸状に形成され、該フィルムのヘイズ値が７０％以上であり、かつ該フィルムの全光線透過率が８０％以上である。
かかる特徴構成により、素子を構成する各層間の屈折率、および表面部の光学的特性が調整され、光取出し効率が改善される。
したがって、本発明の有機ＥＬ素子は、光取出し効率が高く、照明装置、バックライトとしての面状光源、フラットパネルディスプレイ等の表示装置として好ましく使用できる。

And a film is provided on the surface of the transparent substrate on the light extraction side, the surface opposite to the transparent substrate side of the film is formed in an uneven shape, and the haze value of the film is 70% or more And the total light transmittance of this film is 80% or more.
With such a characteristic configuration, the refractive index between the layers constituting the element and the optical characteristics of the surface portion are adjusted, and the light extraction efficiency is improved.
Therefore, the organic EL element of the present invention has high light extraction efficiency, and can be preferably used as a display device such as a lighting device, a planar light source as a backlight, and a flat panel display.

It is a figure which shows typically the organic EL element of 1st Embodiment. It is a figure which shows typically the organic EL element of 2nd Embodiment. It is a figure which shows typically the cross section of the film A produced in the manufacture example 4. FIG. It is a figure which shows typically the cross section of the film B used for the manufacture example 5. FIG. It is a figure which shows typically the cross section of the film C produced in the comparative example 1. FIG.

  Hereinafter, the organic EL element of the present invention will be described in detail according to preferred embodiments thereof. The scale of each member in the drawings referred to in the following description may be different from the actual scale.

The organic EL element of the present invention includes a transparent first electrode, a second electrode having a different polarity from the first electrode, a light emitting layer disposed between the first and second electrodes, and the first electrode. A transparent substrate disposed on the side opposite to the light emitting layer side and a film disposed on the side opposite to the light emitting layer side of the transparent substrate are configured.
When the refractive index of the first electrode is n1 and the refractive index of the transparent substrate is n2, n1 and n2 are represented by the following formula (1)

を満たす。また前記フィルムの前記透明基板側とは反対側の表面が凹凸状に形成され、該フィルムのヘイズ値が７０％以上であり、かつ該フィルムの全光線透過率が８０％以上である。

Meet. Moreover, the surface on the opposite side to the said transparent substrate side of the said film is formed in unevenness | corrugation, the haze value of this film is 70% or more, and the total light transmittance of this film is 80% or more.

[First Embodiment]
The organic EL element of 1st Embodiment of this invention is shown in FIG. In the following description, one side in the thickness direction of the support substrate 1 may be referred to as upper (or upper), and the other in the thickness direction of the support substrate 1 may be referred to as lower (or lower). This hierarchical relationship is set for convenience of explanation, and is not necessarily applied to the process of actually manufacturing the organic EL element and the situation in which it is used.

The organic EL element includes a transparent support substrate (transparent substrate) 1, a light emitting function portion provided on the support substrate 1, and a film 9 disposed on the opposite side of the support substrate 1 from the light emission function portion side. Consists of. The light emitting function unit includes a transparent anode (transparent first electrode) 2, a cathode (second electrode) 4, and a light emitting unit 3 sandwiched between the pair of electrodes. In the present embodiment, the light emitting function unit is provided on the support substrate 1 so that the anode 2 is in contact with the support substrate 1.
The organic EL element is usually provided with a sealing substrate 5 that seals the light emitting function part. The light emitting functional unit is sandwiched between the sealing substrate 5 and the support substrate 1 and is further hermetically sealed by covering a side surface thereof with a resin (not shown).
The light emitting unit 3 includes a light emitting layer 7, a layer 6 provided as necessary between the anode (transparent first electrode) 2 and the light emitting layer 7, and the light emitting layer 7 and the cathode (second electrode) 4. It is comprised from the layer 8 provided between them as needed.

  In the organic EL element of the first embodiment having the above-described configuration, light emitted from the light emitting layer 7 is emitted outside the element through the anode 2, the support substrate 1, and the film 9.

  Below, the physical relationship between the 1st electrode 2 and the transparent support substrate 1 which is the characteristic component of this invention is demonstrated first, and the structure of the film 9 and its characteristic are demonstrated. Thereafter, other components of the organic EL element will be described.

(Relationship between transparent first electrode and transparent substrate)
Assuming that the refractive index of the first electrode 2 is n1 and the refractive index of the transparent substrate (supporting substrate 1) is n2, n1 and n2 satisfy the following equation (1), respectively.

(Transparent substrate)
As the transparent support substrate 1, one having a high light transmittance in the visible light region and not changing in the step of forming the organic EL element is preferably used, and may be a rigid substrate or a flexible substrate. For example, a glass plate, a plastic plate, a polymer film and a silicon plate, and a laminated plate obtained by laminating these are suitably used for the support substrate 1.

  As the support substrate 1, among the exemplified members, a member having a refractive index with a refractive index difference (| n2−n1 |) of less than 0.4 is appropriately used among the first electrodes 2.

(Transparent first electrode)
As shown in the above formula (1), the first electrode 2 has a refractive index n1 of 1.8 or less. The first electrode 2 preferably has a light transmittance in the visible light region of 80% or more, a volume resistivity of 1 Ω · cm or less, and a surface roughness of 100 nm or less. preferable. When the light emitting portion 3 is formed on the flat first electrode 2 having a surface roughness Ra of 100 nm or less, variations in film thickness in each layer can be suppressed, and a short circuit caused by a protrusion or the like can be prevented.

  From the viewpoint of easiness of film formation, the first electrode 2 is preferably configured to include a transparent film main body and a wire-like conductor disposed in the film main body. As the transparent film main body, one having a high light transmittance in the visible light region is preferably used, and includes a resin, an inorganic polymer, an inorganic-organic hybrid compound, and the like. As the transparent film body, a resin having conductivity among the resins is preferably used. Thus, in addition to the wire-like conductor, the electrical resistance of the first electrode 2 can be reduced (hereinafter, the electrical resistance may be abbreviated as resistance) by using the conductive film body. it can. By reducing the resistance of the first electrode 2 in this way, it is possible to suppress a voltage drop at the transparent first electrode 2, realize low voltage driving of the organic EL element, and suppress luminance unevenness.

  The film thickness of the first electrode 2 is appropriately set depending on the electrical resistance, the visible light transmittance, and the like. The film thickness of the first electrode 2 is, for example, 0.03 μm to 10 μm, preferably 0.05 μm to 1 μm.

  The wire-like conductor preferably has a small diameter. As the wire-like conductor, for example, those having a diameter of 400 nm or less are used, those having a diameter of 200 nm or less are suitably used, and those having a diameter of 100 nm or less are more preferable. Since the wire-like conductor disposed on the film body diffracts or scatters the light passing through the first electrode 2, the haze value of the first electrode 2 is increased by arranging this wire-shaped conductor, and the light However, by using a wire-like conductor having a diameter that is about the wavelength of visible light or smaller than the wavelength of visible light, the haze value for visible light is kept low and the light transmittance is improved. be able to. Moreover, since resistance will become high when the diameter of a wire-like conductor is too small, the diameter is preferably 10 nm or more.

  In some cases, a light source that illuminates a wide range, such as a lighting device, is required. For this reason, a higher haze value of the first electrode 2 can impart a diffusion function. Therefore, a higher haze value of the first electrode 2 may be preferable. Therefore, the optical characteristics of the first electrode 2 are appropriately set according to the device in which the organic EL element is used.

There may be one or a plurality of wire-like conductors arranged in the membrane body, and it is preferable that a network structure is formed in the membrane body. For example, in the membrane body, one or a plurality of wire-like conductors form a network structure by being intertwined in a complicated manner throughout the membrane body. Specifically, a structure in which one wire-like conductor is intertwined in a complicated manner or a structure in which a plurality of wire-like conductors are arranged in contact with each other spreads two-dimensionally or three-dimensionally. A network structure is formed. Thus, when the wire-like conductor forms a network structure, the volume resistivity of the first electrode 2 can be lowered.
Moreover, it is preferable that a part of the wire-like conductor is disposed on the surface portion of the first electrode 2 on the light emitting portion 3 side. By arranging the wire-like conductor in this way, the resistance of the surface portion of the first electrode 2 can be lowered.
The wire-like conductor may be, for example, a curved shape or a needle shape. The first electrode 2 having a low volume resistivity can be realized by forming a network structure by contacting curved and / or needle-shaped conductors with each other.

(Wire-like conductor material)
As a material for the wire-like conductor, for example, a low resistance metal such as Ag, Au, Cu, Al, and alloys thereof is preferably used. Wire-like conductors are, for example, a method by NRJana, L. Gearheart and CJMurphy (Chm. Commun., 2001, p617-p618), a method by C. Ducamp-Sanguesa, R. Herrera-Urbina, and M. Figlarz, etc. (J. Solid State Chem., Vol. 100, 1992, p272-p280).

(Method for forming transparent first electrode)
As a method for forming the first electrode 2, for example, a method in which a wire-like conductor is dispersed in a resin by kneading the wire-like conductor in a resin, or a wire-like conductor and a resin are used as a dispersion medium. Examples include a method of forming a film by a coating method using the dispersed dispersion as a coating solution, and a method of coating a wire-like conductor on the surface of a resin film and dispersing the conductor in the film. it can.

In addition, you may add various additives, such as surfactant and antioxidant, to the 1st electrode 2 as needed. Moreover, the kind of resin is suitably selected based on various characteristics calculated | required by the 1st electrode 2, such as a refractive index, light transmittance, and electrical resistance.
Similarly, the amount in which the wire-like conductor is dispersed affects the electrical resistance, haze value, translucency, and the like of the first electrode 2, and is appropriately set according to various characteristics required for the first electrode 2.

  The first electrode 2 of the present embodiment is obtained by applying a dispersion liquid in which a conductive wire-like conductor is dispersed in a dispersion medium to the surface of the support substrate 1 and further curing the coating film. It is done.

  The dispersion is prepared by dispersing a wire-like conductor and a resin in a dispersion medium. As the dispersion medium, those that dissolve the resin are preferable. Chlorine solvents such as chloroform, methylene chloride, and dichloroethane; ether solvents such as tetrahydrofuran; aromatic hydrocarbon solvents such as toluene and xylene; ketones such as acetone and methyl ethyl ketone And ester solvents such as solvent, ethyl acetate, butyl acetate and ethyl cellosolve acetate.

  Examples of the resin include low density or high density polyethylene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-hexene copolymer, ethylene-octene copolymer, ethylene-norbornene copolymer, ethylene. -Polyolefin resins such as domon copolymer, polypropylene, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, ionomer resin; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate; nylon- 6, Nylon-6,6, Metaxylenediamine-Adipic acid condensation polymer; Amide resin such as polymethylmethacrylamide; Acrylic resin such as polymethylmethacrylate; Polystyrene, Styrene-acrylonite Copolymer, styrene-acrylonitrile-butadiene copolymer, styrene-acrylonitrile resins such as polyacrylonitrile; hydrophobic cellulose resins such as cellulose triacetate and cellulose diacetate; polyvinyl chloride, polyvinylidene chloride, polyvinylidene fluoride Halogen-containing resins such as polytetrafluoroethylene; hydrogen-bonding resins such as polyvinyl alcohol, ethylene-vinyl alcohol copolymers and cellulose derivatives; polycarbonate resins, polysulfone resins, polyethersulfone resins, polyetheretherketone resins, polyphenylene Examples thereof include engineering plastic resins such as oxide resins, polymethylene oxide resins, polyarylate resins, and liquid crystal resins.

  Among the exemplified resins, a resin having conductivity is preferably used, and examples of the resin having conductivity include polyaniline and polythiophene derivatives.

  The refractive index of the first electrode 2 is mainly determined by the refractive index of the film body made of resin or the like. Since the refractive index of the film main body is mainly determined by the type of resin used, the first electrode 2 having the intended refractive index can be easily formed by appropriately selecting the type of resin used.

  If a liquid in which a wire-like conductor is dispersed in a photosensitive material and a photocurable monomer used for a photosensitive photoresist is used as a dispersion, the first electrode 2 having a predetermined pattern shape can be easily formed by photolithography. Can be formed.

  As the 1st electrode 2, what does not deform | transform at the temperature heated in the process of forming an organic EL element is preferable. Therefore, the resin constituting the first electrode 2 preferably has a glass transition point Tg of 150 ° C. or higher, more preferably 180 ° C. or higher, and further preferably 200 ° C. or higher. Examples of such a resin include polyether sulfone having a glass transition point Tg of 230 ° C. and a high heat resistant photoresist material.

  The dispersion amount of the wire-like conductor, and the binder and additive mixed in the dispersion liquid as necessary are appropriately set and selected according to various characteristics required for the first electrode 2 and ease of film formation. can do.

  As a method of applying the dispersion liquid in which the wire-like conductor is dispersed, dipping method, coating method by bar coater, coating method by spin coater, doctor blade method, spray coating method, screen mesh printing method, brush coating, spraying, roll coating, etc. The methods generally used in the industry can be mentioned. In addition, when using a thermosetting resin and a photocurable resin, after apply | coating a dispersion liquid, a coating film can be hardened by a heating or light irradiation.

The light transmittance of the first electrode 2 decreases as the weight ratio of the wire-like conductor increases. The weight ratio of the wire-like conductor at which the light transmittance of the first electrode 2 is 80% or more depends on the material and diameter of the wire, but is generally 30% or less. Further, the volume resistivity of the first electrode 2 decreases as the weight ratio of the wire-like conductor increases. The weight ratio of the wire-like conductor in which the volume resistivity of the first electrode 2 is 1 Ω · cm or less depends on the material and diameter of the wire, but is 10 ⁻³ % or more, and the resistivity is 10 ⁻³ Ω.・ It is approximately 1% or more to be cm or less.

  In a conventional bottom emission type organic EL element, ITO formed on a glass substrate has been used as an anode. The refractive index of ITO is about 2, the refractive index of the glass substrate is about 1.5, and the refractive index of the portion of the light emitting portion in contact with ITO (for example, the light emitting layer) is about 1.7. Therefore, in the conventional bottom emission type organic EL element, ITO having a high refractive index is interposed between the glass substrate having a low refractive index and the light emitting layer. Therefore, a part of the light from the light emitting layer is reflected by ITO due to total reflection or the like, and the light from the light emitting layer cannot be extracted efficiently.

On the other hand, in the present embodiment, the refractive index n1 of the first electrode 2 satisfies the above-described formula (1), and as a preferred mode, the portion (for example, the light emitting layer) in contact with the first electrode 2 of the light emitting unit 3 Set to be related. Hereinafter, the refractive index of the portion (for example, the light emitting layer) in contact with the first electrode 2 of the light emitting unit 3 is represented by the symbol “n3”.
By using the first electrode 2 (refractive index: n1) and the transparent support substrate 1 (refractive index: n2) satisfying the relationship of the above-mentioned formula (1), a transparent support substrate is obtained as compared with a conventional organic EL element. 1. An organic EL element having a small difference in refractive index between the transparent first electrode 2 can be formed. Thereby, it is possible to suppress the light from the light emitting layer 7 from being reflected by the first electrode 2 and to improve the light extraction efficiency of the organic EL element. Further, if the transparent first electrode 2 and the transparent support substrate 1 satisfying the relationship of | n1-n3 | <0.4 are used, the support substrate 1, the first electrode 2, and the first electrode 2 of the light emitting unit 3 are used. The difference in refractive index between the layers in contact (for example, the light emitting layer 7) can be further reduced, the light from the light emitting layer 7 is suppressed from being reflected by the first electrode 2, and the light extraction efficiency of the organic EL element is further increased. Can be improved. As a result, an organic EL element with high luminous efficiency can be realized. As described above, since “n3” is usually about 1.7, the relationship of | n1−n3 | <0.4 can be satisfied in many cases by using the first electrode 2 satisfying the expression (1).

  Further, since the first electrode 2 can be formed by a simple coating method, the first electrode 2 can be formed at a low cost. Furthermore, since the characteristics of the first electrode 2 are determined by the type of the resin and the wire-shaped conductor and the shape of the wire-shaped conductor, the intended optical characteristics and electrical characteristics can be obtained simply by selecting these appropriately. The first electrode 2 shown can be easily obtained.

(the film)
The film 9 is provided on the surface of the support substrate (transparent substrate) 1 opposite to the light emitting layer 7 side. The film 9 has a planar surface on the light emitting layer 7 side, and a surface opposite to the light emitting layer 7 side is formed in an uneven shape. The film 9 has a haze value of 70 or more and a total light transmittance of 80% or more.

  The planar surface of the film 9 is bonded to the transparent support substrate 1. The film 9 is affixed to the support substrate 1 using bonding agents, such as a thermosetting resin, a photocurable resin, an adhesive agent, and an adhesive material, for example. When a thermosetting resin is used, the film 9 can be bonded to the support substrate 1 by bonding the film 9 to the support substrate 1 and then heating at a predetermined temperature. Moreover, when using a photocurable resin, after bonding the film 9 to the support substrate 1, the film 9 can be adhere | attached on the support substrate 1 by irradiating the film 9, for example with an ultraviolet-ray. In addition, when forming the film 9 directly on the support substrate 1, and when the bonding agent is previously provided in the film 9, the said bonding agent does not need to be used.

  When an air layer is formed between the film 9 and the support substrate 1, reflection occurs at the interface of the air layer, so that an air layer is not formed between the film 9 and the support substrate 1. It is preferable that the film 9 is attached to the support substrate 1 in close contact. Of the refractive index of the film 9, the refractive index of the bonding agent, and the refractive index of the layer to which the film 9 is bonded (supporting substrate 1 in this embodiment), the maximum refractive index and the minimum refractive index. A smaller difference is preferable because reflection at the bonding surface can be suppressed. Specifically, the difference is preferably within 0.2, and more preferably within 0.1.

  The film 9 of the present embodiment has an uneven surface on the side opposite to the light emitting layer 7 side, a haze value of 70% or more, and a total light transmittance of 80% 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 80%, light may not be extracted sufficiently. When a film is used for an organic EL device, sufficient light extraction efficiency may not be obtained, but by using the film 9 having a haze value of 70% or more and a total light transmittance of 80% or more, An organic EL element with high extraction efficiency can be realized.

The haze value is represented by the following formula.
Haze value (cloudiness value) = (diffuse transmittance (%) / total light transmittance (%)) × 100 (%).
The haze value can be measured by the method described in JIS K 7136 “How to determine the haze of a plastic-transparent material”.

  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 size (width) of the convex or concave surface in the width direction perpendicular to the thickness direction of the film 9 is too large, the luminance on the surface of the film 9 becomes non-uniform, and if it is too small, the production cost of the film 9 increases. Therefore, it is preferably 0.5 μm to 20 μm, and more preferably 1 μm to 2 μm. Further, the height of the convex surface or concave surface in the thickness direction of the film 9 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 concave and convex shape is formed. It is preferably not more than the size (width) of the convex surface or not more than the period in which the uneven shape is formed, and is 0.25 μm to 10 μm, preferably 0.5 μm to 1.0 μm.

  The shape of the convex surface or the concave surface is not particularly limited, but a shape having a curved surface is preferable, for example, a hemispherical shape is preferable. The concave surface or the convex surface is preferably arranged regularly, for example, preferably arranged in a grid pattern. Moreover, 60% or more of the area of the surface of the film 9 is preferable in the area of the surface of the film 9 where the concave and convex surfaces are formed.

The material used for forming the film 9 may be any material as long as the film 9 is formed transparently. For example, a polymer material and glass may be used. Examples of the polymer material constituting the film 9 include polyarylate, polycarbonate, polycycloolefin, polyethylene naphthalate, polyethylene sulfonic acid, and polyethylene terephthalate. The film 9 includes a support made of, for example, the above-described polymer material and glass, and a thin film formed on the surface of the support, the surface opposite to the surface in contact with the support being 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 9, When it is too thin, handling will become difficult, and since a total light transmittance will become low when too thick, 20 micrometers-1000 micrometers are preferable.

  Next, the manufacturing method of the film 9 is demonstrated. The film 9 of this embodiment is obtained by forming an uneven shape on the surface of the film. The size (width) of the concave surface or convex surface formed on the surface is preferably the same as or larger than the wavelength of light, and preferably 0.1 μm to 100 μm.

The film 9 made of an inorganic material such as glass can be obtained by etching a portion of the surface of the base made of an inorganic material that forms an uneven shape. Specifically, an uneven surface can be formed by patterning a protective film on the surface of a base made of an inorganic material and applying chemical etching or vapor phase etching. The protective film can be patterned using, for example, a photoresist.
In the film 9 made of a polymer material, a method of transferring the concavo-convex shape of the metal plate by pressing the concavo-convex metal plate on the heated film, using a roll having a concavo-convex surface, the polymer sheet or A method of rolling a film, a method of extruding a polymer sheet from a slit having a concavo-convex shape, and dropping a solution or dispersion containing a polymer material onto a base having a concavo-convex surface (hereinafter sometimes referred to as casting) There is a method for forming a film, and after forming a film made of a monomer, a method for selectively photopolymerizing a part of the film and removing an unpolymerized part. The concavo-convex shape can be formed on the surface by a method such as casting to transfer the water droplet structure to the surface.

  Among these methods, when a polymer material is used, a method in which a polymer solution is cast on a base and a water droplet structure is transferred to the surface under high humidity conditions is preferably used because of easy production. This method is a structure manufacturing method applying a dissipative process which is a kind of self-organization (see, for example, G. Widawski, M. Rawiso, B. Francois, Nature, p. 369-p. 387 (1994)).

  First, the polymer material to be the film 9 described above is dissolved in a solvent to prepare a solution for the film 9. Examples of the solvent include dichloromethane and chloroform. As the solution for the film 9, one having a high viscosity is preferable. The solution for the film 9 preferably has a high concentration of the polymer material to be the film 9, and the concentration of the polymer material with respect to 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 the film 9.

  Next, the solution containing the material used as the film 9 is apply | coated on the base with which the film 9 is formed on the surface. Specifically, the prepared solution for the film 9 is cast on a base under high humidity to form a liquid film composed of the solution for the film 9. When a support substrate is used as a base for casting the solution for the film 9, the film 9 is directly formed on the support substrate 1.

  Next, the solution applied on the surface of the base is held in an atmosphere with a humidity of 80% to 90%, and a film is formed by evaporating the solvent (solvent) in the solution during and / or after holding. When the liquid film is placed under high humidity, water vapor in the atmosphere is liquefied and a plurality of droplets are formed on the surface of the liquid film. The droplets are substantially spherical and are discretely formed on the surface of the liquid film. The droplets formed on the liquid film grow with time as the water vapor is further liquefied. The droplets on the liquid film increase in diameter and weight with the passage of time. Therefore, almost half of the droplet sinks into the liquid film due to its own weight. Further, since the solvent (solvent) in the liquid film evaporates with time, the shape of the droplet is transferred to the film 9 at the time of drying. The film 9 formed in this way is provided with a plurality of concave surfaces on the surface, and is formed in an uneven shape. Specifically, a plurality of hemispherical depressions having a diameter of 1 μm to 100 μm are formed on the surface of the film 9. In addition, by holding the film 9 in the range of 80% to 90% humidity, the film may be dried in a lower humidity atmosphere after the hemispherical depression is formed on the surface, and 80% to 90%. The film may be dried by holding the film for a long time in the% range.

In the method for producing the film 9, the production of the film 9 is controlled by controlling the application of the solution for the film 9 so that the film thickness becomes a predetermined value and adjusting the humidity when the liquid film is dried. The haze value of the film 9 can be controlled.
Specifically, the film thickness of the liquid film at the start of drying is controlled so that the film thickness of the film 9 formed through the film forming step becomes a predetermined film thickness within a range of 100 μm to 200 μm, and 80 By controlling the humidity so as to be a predetermined humidity within a range of% to 90%, the film 9 having a desired haze value of 70 or more can be formed.

The haze value of the film 9 can be controlled by controlling the humidity and the film thickness, depending on the concentration of the polymer material, etc., but the time until the surface of the liquid film dries when the humidity and the film thickness are changed. This is because the size of the concavo-convex shape and the density of the concave surface change accordingly, and the humidity has a great influence on the structure construction of the concave surface to be formed, such as the regularity of the arrangement of the concave surface. Guessed.
The film thickness of the produced film 9 can be controlled by adjusting the film thickness of the liquid film at the start of drying. In addition, 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 9 is controlled by changing the solvent (solvent) to be used. You can also.

  By the method described above, a large-area film 9 showing the intended optical characteristics can be produced simply and inexpensively by simple control of adjusting the application amount and humidity of the solution, for example.

  As described above, the film 9 can be formed directly on the support substrate 1 by casting the solution for the film 9 on the surface of the support substrate 1, but the film is formed on a predetermined base. Later, the film may be bonded to the support substrate 1.

According to the above-described configuration, the film 9 is disposed on the outermost surface portion on the side from which the light of the organic EL element is emitted. The light radiated from the light emitting layer 7 passes through the support substrate 1 and the film 9, and is emitted to the outside such as air through the uneven surface. That is, light is emitted to the outside through the uneven surface.
If the surface opposite to the light emitting layer 7 side of the film 9 is a flat surface, most of the light emitted from the light emitting layer 7 is not emitted to the outside due to total reflection on this plane, but the film of this embodiment. Since the 9 surfaces are formed in an uneven shape, total reflection is suppressed, so that light can be emitted efficiently. In particular, since the film 9 has a haze value of 70% or more and a total light transmittance of 80% 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 9 is provided with a plurality of concave surfaces, and these concave surfaces exhibit a function similar to a concave lens. By providing such a film 9, the radiation angle of the light emitted from the organic EL element can be widened.

  Subsequently, components of the organic EL element other than the support substrate 1, the anode (first electrode) 2 and the film 9 described above will be described in detail below.

(Light emitting part)
The light emitting unit 3 is provided between the anode (first electrode) 2 and the cathode (second electrode) 4. The light emitting unit 3 includes at least a light emitting layer 7. One or more predetermined layers 6 are provided between the anode 2 and the light emitting layer 7 as necessary. In addition, one or a plurality of predetermined layers 8 are provided between the light emitting layer 7 and the cathode 4 as necessary.

(Layer provided between the anode and the light emitting layer)
Examples of the layer 6 provided between the anode (first electrode) 2 and the light emitting layer 7 include a hole injection layer, a hole transport layer, and an electron block layer. The hole injection layer is a layer having a function of improving the efficiency of hole injection from the anode (first electrode) 2. The hole transport layer is a layer having 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 is a layer having 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 fact that the electron blocking layer has a function of blocking electron transport makes it possible, for example, to produce an element that allows only electron current to flow and confirm the blocking effect by reducing the current value.

(Layer provided between the cathode and the light emitting layer)
Examples of the layer 8 provided between the light emitting layer 7 and the cathode (second electrode) 4 include an electron injection layer, an electron transport layer, and a hole blocking layer. When both the electron injection layer and the electron transport layer are provided between the cathode 4 and the light emitting layer 7, the layer in contact with the cathode is referred to as an electron injection layer, and the layers other than the electron injection layer are referred to as an electron transport layer. . The electron injection layer is a layer having a function of improving electron injection efficiency from the cathode. The electron transport layer is a layer having 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 is a layer having 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. The fact that the hole blocking layer has a function of blocking hole transport makes it possible, for example, to produce an element that allows only a hole current to flow, and confirm the blocking effect by reducing the current value.

A combination example of the layer configuration of the light emitting function part in 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 light emitting functional unit 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 light emitting functional unit having two light emitting layers is obtained. Includes the layer structure shown in the following q). The (structural units A) may be the same as or different from each other.
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 configuration of the light emitting functional unit include the layer configuration 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 the structural unit B is stacked in x stages. Represents the body. The plurality (structural unit B) may be the same or different.
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, the anode is usually arranged on the support substrate side as in the present embodiment, but the cathode may be arranged on the support substrate side by reversing the stacking order.

In the organic EL device of this embodiment, an insulating layer having a thickness of 2 nm or less may be further provided adjacent to the electrode in order to improve adhesion with the electrode or charge injection from the electrode. In addition, a thin buffer layer may be inserted between each of the aforementioned layers in order to improve adhesion at the interface or prevent mixing.
Hereinafter, the configuration of each layer will be described in more detail.

(Hole injection layer)
As a material constituting the hole injection layer, a known material can be appropriately used. Examples of the material constituting the hole injection layer include phenylamine, starburst amine, phthalocyanine, hydrazone derivative, carbazole derivative, triazole derivative, imidazole derivative, oxadiazole derivative having amino group, vanadium oxide, oxidation Examples thereof include oxides such as tantalum, tungsten oxide, molybdenum oxide, ruthenium oxide, and aluminum oxide, amorphous carbon, polyaniline, and polythiophene derivatives.

  As a film formation method of the hole injection layer, for example, film formation from a solution containing a material (hole injection material) that becomes the hole injection layer can be mentioned. As a solvent used for film formation from a solution, a solvent that dissolves a hole injection material is preferable. Chlorine solvents such as chloroform, methylene chloride, and dichloroethane, ether solvents such as tetrahydrofuran, and aromatic carbonization such as toluene and xylene. Examples thereof include hydrogen solvents, ketone solvents such as acetone and methyl ethyl ketone, ester solvents such as ethyl acetate, butyl acetate and ethyl cellosolve acetate, and water.

  As a film forming method from a solution, a spin coating method, a casting method, a micro gravure coating method, a gravure coating method, a bar coating method, a roll coating method, a wire bar coating method, a dip coating method, a spray coating method, a screen printing method, Examples of the application method include a flexographic printing method, an offset printing method, and an ink jet printing method.

  Considering the ease of production and the applied voltage, the thickness of the hole injection layer is preferably about 5 to 300 nm.

(Hole transport layer)
As a material constituting the hole transport layer, for example, N, N′-diphenyl-N, N′-di (3-methylphenyl) 4,4′-diaminobiphenyl (TPD), 4,4′-bis [N Aromatic amine derivatives such as-(1-naphthyl) -N-phenylamino] biphenyl (NPB), polyvinylcarbazole or derivatives thereof, polysilane or derivatives thereof, polysiloxane derivatives having aromatic amines in the side chain or main chain, pyrazoline Derivative, arylamine derivative, 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 a derivative thereof.

  Among these, as the hole transport material used for the hole transport layer, polyvinyl carbazole or a derivative thereof, polysilane or a derivative thereof, a polysiloxane derivative having an aromatic amine compound group in a side chain or a main chain, polyaniline or a derivative thereof, Polymeric hole transport materials such as polythiophene or derivatives thereof, polyarylamine or derivatives thereof, poly (p-phenylene vinylene) or derivatives thereof, or poly (2,5-thienylene vinylene) or derivatives thereof are preferred, and more preferred Is polyvinyl carbazole or a derivative thereof, polysilane or a derivative thereof, and a polysiloxane derivative having an aromatic amine in the side chain or main chain. In the case of a low-molecular hole transport material, it is preferably used by being dispersed in a polymer binder.

  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.

As a solvent used for film formation from a solution, a solvent that dissolves a hole transport material is preferable. Chlorine solvents such as chloroform, methylene chloride, and dichloroethane; ether solvents such as tetrahydrofuran; aromatic carbonization such as toluene and xylene. Examples thereof include hydrogen solvents, ketone solvents such as acetone and methyl ethyl ketone, and ester solvents such as ethyl acetate, butyl acetate and ethyl cellosolve acetate.
Examples of the film forming method from a solution include the same coating method as the above-described film forming method of the hole injection layer.

  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.

  The thickness of the hole transport layer is appropriately set according to the required characteristics, and is preferably about 1 to 1000 nm, more preferably 2 to 500 nm, taking into account the ease of production and the applied voltage. More preferably, it is 5 nm to 200 nm.

(Light emitting layer)
The light emitting layer 7 has an organic substance that mainly emits fluorescence or phosphorescence. Furthermore, the light emitting layer may contain a dopant material. As the organic substance, a low molecular compound and / or a high molecular compound is used. A polymer compound is suitable for a coating method because it has high solubility in a solvent. Therefore, when the light emitting layer is formed by a simple coating method, it is preferable to use a material containing a polymer compound as the light emitting material constituting the light emitting layer, and the light emitting layer has a polystyrene-equivalent number average molecular weight of 10 ³ to 10 ³ . It is preferable that the polymer compound is 10 ⁸ . Examples of the light emitting material constituting the light emitting layer include the following.

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

(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)
Polymeric materials include polyparaphenylene vinylene derivatives, polythiophene derivatives, polyparaphenylene derivatives, polysilane derivatives, polyacetylene derivatives, polyfluorene derivatives, polyvinylcarbazole derivatives, and polymerized chromophores and metal complex light emitting materials. Etc.

Among the light emitting materials, examples of the material that emits blue light include distyrylarylene derivatives, oxadiazole derivatives, and polymers thereof, polyvinylcarbazole derivatives, polyparaphenylene derivatives, and polyfluorene derivatives. Of these, polymer materials such as polyvinyl carbazole derivatives, polyparaphenylene derivatives, and polyfluorene derivatives are preferred.
Examples of materials that emit green light include quinacridone derivatives, coumarin derivatives, and polymers thereof, polyparaphenylene vinylene derivatives, polyfluorene derivatives, and the like. Of these, polymer materials such as polyparaphenylene vinylene derivatives and polyfluorene derivatives are preferred.
Examples of materials that emit red light include coumarin derivatives, thiophene ring compounds, and polymers thereof, polyparaphenylene vinylene derivatives, polythiophene derivatives, and polyfluorene derivatives. Among these, polymer materials such as polyparaphenylene vinylene derivatives, polythiophene derivatives, and polyfluorene derivatives are preferable.

(Dopant material)
A dopant can be added to the light emitting layer for the purpose of improving the light emission efficiency and changing the light emission wavelength. Examples of such dopants 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 about 20-2000 mm normally.

(Light-emitting layer deposition method)
As a method for forming the light emitting layer, a film forming method from a solution, a vacuum deposition method, a transfer method, or the like can be used. Specific examples of the solvent used for film formation from the solution include the same solvents as those exemplified as the solvent for dissolving the hole injection material when forming the hole injection layer from the above solution.

  As a method for applying a solution containing a light emitting material, a spin coating method, a casting method, a micro gravure coating method, a gravure coating method, a bar coating method, a roll coating method, a wire bar coating method, a dip coating method, a slit coating method, a capillary Coating methods such as coating methods, spray coating methods, nozzle coating methods, etc., gravure printing methods, screen printing methods, flexographic printing methods, offset printing methods, reverse printing methods, printing methods such as inkjet printing methods, etc. may be used. it can. A printing method such as a gravure printing method, a screen printing method, a flexographic printing method, an offset printing method, a reversal printing method, and an ink jet printing method is preferable in that pattern formation and multi-coloring are easy. In the case of a sublimable low-molecular compound, a vacuum deposition method can be used. Furthermore, a method of forming a light emitting layer only at a desired place by laser transfer or thermal transfer can be used.

(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.

(Electron transport layer)
As the material constituting the electron transport layer, known materials can be used, such as oxadiazole derivatives, anthraquinodimethane or its derivatives, benzoquinone or its derivatives, naphthoquinone or its derivatives, anthraquinone or its derivatives, tetracyanoanthraquinodi. Examples include methane or its derivatives, fluorenone derivatives, diphenyldicyanoethylene or its derivatives, diphenoquinone derivatives, or metal complexes of 8-hydroxyquinoline or its derivatives, polyquinoline or its derivatives, polyquinoxaline or its derivatives, polyfluorene or its derivatives, etc. The

Of these, oxadiazole derivatives, benzoquinone or derivatives thereof, anthraquinones or derivatives thereof, or metal complexes of 8-hydroxyquinoline or derivatives thereof, polyquinoline or derivatives thereof, polyquinoxaline or derivatives thereof, polyfluorene or derivatives thereof are preferred, 2- (4-biphenylyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole, benzoquinone, anthraquinone, tris (8-quinolinol) aluminum, and polyquinoline are more preferable.
The film thickness of the electron transport layer varies depending on the material used, and is appropriately set so that the drive voltage and the light emission efficiency are appropriate. 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.

(Second electrode)
The second electrode 4 is an electrode disposed to face the first electrode 2 and is used as a cathode in the first embodiment. As such a cathode material, a material having a small work function and easy electron injection into the light emitting layer is preferable. The cathode material is preferably a material having high electrical conductivity and high visible light reflectance. Examples of such a cathode material include metals, metal oxides, alloys, graphite or graphite intercalation compounds, and inorganic semiconductors such as zinc oxide (ZnO).

  As the metal, an alkali metal, an alkaline earth metal, a transition metal, a group 13 metal of the periodic table, or the like can be used. Specific examples of these metals include lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, gold, silver, platinum, copper, manganese, titanium, cobalt, nickel, tungsten, tin, and aluminum. , Scandium, vanadium, zinc, yttrium, indium, cerium, samarium, europium, terbium, ytterbium, and the like.

  Examples of the alloy include alloys containing at least one of the above metals. Specifically, magnesium-silver alloy, magnesium-indium alloy, magnesium-aluminum alloy, indium-silver alloy, lithium-aluminum alloy, lithium -A magnesium alloy, a lithium-indium alloy, a calcium-aluminum alloy, etc. can be mentioned.

  The cathode (second electrode) 4 may have a laminated structure of two or more layers. The electron injection layer may be used as a cathode.

  The film thickness of the cathode (second electrode) 4 can be appropriately selected in consideration of electric conductivity and durability, and is, for example, 10 nm to 10 μm, preferably 20 nm to 1 μm, more preferably 50 nm to 500 nm. It is.

  Examples of the method for forming the cathode (second electrode) 4 include a vacuum deposition method, a sputtering method, and a laminating method in which a metal thin film is thermocompression bonded.

(Sealing substrate)
After the cathode (second electrode) 4 is formed as described above, it is preferable to form the sealing substrate 5 for sealing the light emitting function unit. The sealing substrate 5 is usually composed of the same members as the support substrate 1. A sealing film may be provided instead of the sealing substrate 5. The sealing film has one or more inorganic layers and one or more organic layers. The number of layers is determined according to the required characteristics, and basically, the inorganic layer and the organic layer are alternately stacked.

  Note that a plastic substrate has higher permeability to gases such as oxygen and water than a glass substrate. Since the luminescent material is easily oxidized and easily deteriorates when it comes into contact with oxygen, water, or the like, when a plastic substrate is used as the substrate 1, it is preferable to perform a treatment for improving the gas barrier property on the substrate in advance. For example, it is preferable to stack a lower sealing film having a high barrier property against gas or the like on a plastic substrate, and then stack a light emitting function part on the lower sealing film. This lower sealing film is usually composed of the same member as the sealing film.

[Method of manufacturing organic EL element]
The organic EL element of this embodiment can be manufactured by sequentially forming each constituent element by the forming method described in the section of each constituent element. That is, the manufacturing method of the organic EL element of this embodiment is
(1) preparing a transparent support substrate 1;
(2) A step of laminating each layer constituting the light emitting function part on the support substrate 1,
(3) having a step of forming a film.
In addition, when the film 9 is separately formed without being directly formed on the support substrate, the method further includes a step of attaching the formed film 9 to the transparent support substrate 1.

[Second Embodiment]
Next, the organic EL element of 2nd Embodiment of this invention is demonstrated with reference to FIG. The organic EL element of the first embodiment is a bottom emission type element that emits light from the supporting substrate side, whereas the organic EL element of the second embodiment is a top emission type that emits light from the sealing substrate side. Element. In the first embodiment, the film is provided on the support substrate, but in this embodiment, the film is provided on the sealing substrate.
The organic EL element of the second embodiment is configured by laminating a support substrate 21, a light emitting function unit, a sealing substrate 25, and a film 29 in this order. The layer structure of the light emitting function unit is the same as the layer structure of the light emitting function unit of the first embodiment. However, in the organic EL element of the second embodiment, the transparent first electrode corresponds to the cathode 24, and the first electrode The second electrode having a different polarity corresponds to the anode 22, and the transparent substrate corresponds to the sealing substrate 25.
The configuration of each layer will be briefly described below, but the description of the same configuration as in the first embodiment will be omitted.

(Support substrate)
As the support substrate 21, the same support substrate as that of the above-described embodiment can be used. Note that the support substrate 21 of the present embodiment may be opaque.

(anode)
In the present embodiment, the anode 22 is the second electrode. In general, the anode 22 is preferably provided as a reflective electrode that reflects light emitted from the light emitting layer 27 toward the cathode (transparent first electrode) 24. The anode 22 preferably has a reflectance with respect to visible light of 80% or more.

  From the viewpoint of the ability to supply holes to the light emitting portion 23, the work function of the surface portion on the light emitting layer 27 side of the anode 22 is preferably 4.0 eV or more. The material of the anode 22 is preferably a material having a large work function and easy hole injection into the light emitting layer 27, and a material having high electrical conductivity and high visible light reflectance. Examples of such materials include metals, metal oxides, alloys, graphite or graphite intercalation compounds, and inorganic semiconductors such as zinc oxide (ZnO).

  The anode 22 may have a laminated structure of two or more layers, and a laminated body in which a light reflecting layer made of a highly light reflecting metal and a high work function material layer made of a material having a work function of 4.0 eV or more are preferably laminated. The film thickness of the anode 22 can be appropriately selected in consideration of electric conductivity and durability, and is, for example, 10 nm to 10 μm, preferably 20 nm to 1 μm, and more preferably 50 nm to 500 nm.

As specific configuration examples of such an anode, the following (1) to (15) can be exemplified.
(1) Al
(2) Ag
(3) Ag-MoO ₃
(4) Alloy of Ag, Pd and Cu-ITO
(5) Alloy of Al and Nd-ITO
(6) Alloy of Mo and Cr-ITO
(7) Cr-Al-Cr-ITO
(8) Cr-Ag-Cr-ITO
(9) Cr—Ag—Cr—ITO—MoO ₃
(10) Ag—Pd—Cu alloy—IZO
(11) Al-Nd alloy-IZO
(12) Alloy of Mo and Cr-IZO
(13) Cr-Al-Cr-IZO
(14) Cr-Ag-Cr-IZO
(15) Cr—Ag—Cr—IZO—MoO ₃
In addition, in the description of said (3)-(15), symbol "-" represents the interface between each lamination | stacking, and the left side of description is a board | substrate side. In order to obtain a sufficient light reflectance, the film thickness of the highly light-reflective metal layer such as Al, Ag, Al alloy, or Ag alloy is preferably 50 nm or more, and more preferably 80 nm or more. The film thickness of the high work function material layer such as ITO or IZO is usually in the range of 5 nm to 500 nm.

  Examples of the method for forming the anode 22 include a vacuum deposition method, a sputtering method, and a laminating method in which a metal thin film is thermocompression bonded.

(Transparent cathode)
The transparent cathode 24 is a transparent first electrode in the present invention, and is formed in the same manner as the transparent anode 2 in the first embodiment.

(Sealing substrate)
The transparent sealing substrate 25 is a transparent substrate in the present invention, and can be composed of the same member as the sealing substrate of the above-described embodiment. The refractive index n2 of the sealing substrate 25 and the refractive index n1 of the transparent cathode 24 have the relationship shown in the above formula (1). As described above, a glass plate, a plastic plate, or the like is used as the sealing substrate 25 and is appropriately selected within a range that satisfies the formula (1).

(the film)
In the second embodiment, a film 29 is provided on the transparent sealing substrate 25. The film 29 is made of the member of the film 9 used in the first embodiment.

  As described above, in the second embodiment, the refractive index n1 of the cathode 24 corresponding to the transparent first electrode and the refractive index n2 of the sealing substrate 25 corresponding to the transparent substrate satisfy the above formula (1), and Since the predetermined film 29 is provided on the outermost surface portion from which light is emitted, the light extraction efficiency is improved as in the first embodiment. Therefore, as in the first embodiment, an organic EL element with high luminous efficiency can be realized in the second embodiment.

  In FIG. 1 and FIG. 2, the side surface of the light emitting function portion between the support substrate and the sealing substrate is exposed, but is usually finally sealed with resin.

  The organic EL element of the first embodiment has a bottom emission type element structure, but has the same bottom emission type element structure, and the transparent first electrode has the light emitting function unit stacked in reverse order. The present invention can also be applied to an organic EL element having a structure in which a transparent cathode is provided on the support substrate side and an anode is provided on the sealing substrate side as the second electrode.

  In addition, the organic EL element of the second embodiment has a top emission type element structure, but has the same top emission type element structure. The present invention can also be applied to an organic EL element having a structure in which a transparent anode is provided on the sealing substrate side and a cathode is provided on the support substrate side as the second electrode.

Production example

  Hereinafter, although this invention is demonstrated more concretely based on a manufacture example and a comparative example, this invention is not limited to the following illustrations.

  In the following Production Examples 1 to 3, the refractive indexes of the transparent substrate and the transparent first electrode are controlled within a specific range.

(Production Example 1)
As a wire-like conductor, a silver nanowire (major axis average length 1 μm, short) whose surface is protected with an amino group-containing polymer dispersant (product name “Solsperse 24000SC” manufactured by IC Japan Ltd.) Axial average length of 10 nm) is used. 2 g of toluene dispersion of silver nanowire (containing 1.0 g of silver nanowire) and trimethylolpropane triacrylate (made by Shin-Nakamura Chemical Co., Ltd., trade name “NK Ester-TMPT”) which is a photocurable monomer serving as the film body 0.25 g is mixed, and further, 0.0025 g of a polymerization initiator (trade name “Irgacure 907” manufactured by Ciba-Geigy Corporation of Japan) is added. This mixed solution is applied to a 0.7 mm thick glass substrate (corresponding to a transparent substrate), heated on a hot plate at 110 ° C. for 20 minutes to dry the solvent, and further irradiated with a UV lamp (6000 mW / cm ² ). By curing, a transparent conductive film (corresponding to a transparent first electrode) having a film thickness of 150 nm is obtained. By forming the film in this manner, a transparent conductive film (corresponding to a transparent first electrode) having a transmittance of 80% or more, a volume resistivity of 1 Ω · cm or less, and a surface roughness of 100 nm or less is obtained.

  Since the refractive index of the photocurable resin constituting the film body is 1.47, the refractive index of the obtained transparent conductive film is also 1.47. An organic EL element can be obtained by using this transparent plate with a transparent conductive film as a transparent substrate having a transparent first electrode or a sealing substrate. In the obtained organic EL element, light extraction efficiency and light emission efficiency are improved.

(Production Example 2)
As a wire-like conductor, a silver nanowire (major axis average length 1 μm, short) whose surface is protected with an amino group-containing polymer dispersant (product name “Solsperse 24000SC” manufactured by IC Japan Ltd.) Axial average length of 10 nm) is used. 1. 2 g of this silver nanowire in toluene dispersion (containing 1.0 g of silver nanowire) and a poly (ethylenedioxythiophene) / polystyrene sulfonic acid solution (trade name “BaytronP” manufactured by Starck Co., Ltd.) to be the membrane body. Mix with 5 g. This mixed solution is applied to a glass substrate (corresponding to a transparent substrate) having a thickness of 0.7 mm, heated on a hot plate at 200 ° C. for 20 minutes, and dried to form a transparent conductive film (a transparent first film having a thickness of 150 nm). Corresponding to the electrode). By forming the film in this manner, a transparent conductive film (corresponding to a transparent first electrode) having a transmittance of 80% or more, a volume resistivity of 1 Ω · cm or less, and a surface roughness of 100 nm or less is obtained.

  Since the refractive index of “BaytronP” constituting the film main body is 1.7, the refractive index of the obtained transparent conductive film is also 1.7. An organic EL element can be obtained by using this transparent plate with a transparent conductive film as a transparent substrate having a transparent first electrode or a sealing substrate. In the obtained organic EL element, light extraction efficiency and light emission efficiency are improved.

(Production Example 3)
As a wire-like conductor, a silver nanowire (major axis average length 1 μm, short) whose surface is protected with an amino group-containing polymer dispersant (product name “Solsperse 24000SC” manufactured by IC Japan Ltd.) Axial average length of 10 nm) is used. A mixture of 2.5 g of a poly (ethylenedioxythiophene) / polystyrene sulfonic acid solution (trade name “BaytronP” manufactured by Starck Co., Ltd.) to be the membrane body and 0.125 g of dimethyl sulfoxide; 2 g of toluene dispersion (containing 1.0 g of silver nanowires) is mixed. This mixed solution is applied to a 0.7 mm thick glass substrate (corresponding to a transparent substrate), heated on a hot plate at 200 ° C. for 20 minutes, and dried to form a conductive film having a thickness of 150 nm (on a transparent first electrode). Equivalent) By forming a film in this way, a transparent conductive film having a transmittance of 80% or more, a volume resistivity of 1 Ω · cm or less, and a surface roughness of 100 nm or less is obtained.

  Since the refractive index of “BaytronP” constituting the film main body is 1.7, the refractive index of the obtained transparent conductive film is also 1.7. An organic EL element can be obtained by using this transparent plate with a transparent conductive film for a transparent substrate or a sealing substrate having a transparent first electrode. In the obtained organic EL element, light extraction efficiency and light emission efficiency are improved.

  In the following Production Examples 4 and 5 and Comparative Examples 1 to 3, it was confirmed that the light extraction efficiency can be controlled by providing a film on a transparent support substrate.

(Production Example 4)
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 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. In the first stage filtration, a 0.45 μm diameter filter was used, and in the second stage filtration, a 0.2 μm diameter filter was used. The solution obtained by filtration was thinned by a spin coating method, 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 on the anode.

  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%. Using the prepared solution, a thin film was formed on the surface of the hole injection layer by spin coating, and then 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. did.

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, in order to produce a film, first, a solution for the film was prepared. 6.32 g of polycarbonate was dissolved in 20.7 g of dichloromethane to prepare a 23.4 wt% solution. This solution was mixed with Novec (manufactured by Sumitomo 3M) as a fluorosurfactant. The concentration of Novec in the mixed solution was 0.8 wt% to obtain a film solution. The obtained film solution was cast on a glass base so that the film thickness after film formation was about 150 μm in a constant temperature and humidity chamber with a humidity of 85%. 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 thereto 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 230 μm.

(Production Example 5)
An organic EL element different from the organic EL element of Production Example 4 only in film was produced. In Production Example 3 (5), 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 different from the organic EL element of Production Example 4 only in film was produced. As the film solution, the same solution as in Preparation Example 1 was used. In a constant temperature and humidity chamber with a humidity of 50%, the film 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 4, film C was attached to a support substrate in the same manner as in Production Example 4 to produce an organic EL device.

(Comparative Example 2)
An organic EL element different from the organic EL element of Production Example 4 only in film was produced. The same solution as in Preparation Example 4 was used as the film solution. In a constant temperature and humidity chamber with a humidity of 85%, the film 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 4, film D was attached to a support substrate in the same manner as in Production Example 4 to produce an organic EL device.

(Comparative Example 3)
An organic EL element different from the organic EL element of Production Example 4 only in film was produced. The same solution as in Preparation Example 4 was used as the film solution. In a constant temperature and humidity chamber with a humidity of 85%, the film 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 adhesive as in Production Example 4, film E was attached to a support substrate in the same manner as in Production Example 4 to produce an organic EL device.

(Observation of film surface)
The surfaces of the films used in Production Examples 4 and 5 and Comparative Examples 1, 2, and 3 were observed with a scanning electron microscope (SEM). 3 is a diagram schematically showing a cross section of the film A produced in Production Example 4, FIG. 4 is a diagram schematically showing a cross section of the film B used in Production Example 5, 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 4, 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 the concave surface was formed over the entire surface of the film A.

  In the film B used for Production Example 5, it was confirmed that the surface of the film was formed in an uneven shape. It was confirmed that the 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 4 and Comparative Examples 1, 2, and 3, and the characteristics of the films used in Production Examples 4, 5 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 humidity and the film thickness 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 element 1)
The light intensity of the organic EL element to which the films prepared in Production Examples 4 and 5 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 by passing a current of 0.15 mA through the organic EL element, measuring the angle dependency of the emission intensity at that time, and integrating the emission intensity at all angles.

In the organic EL element of Production Example 4, the light extraction efficiency was increased 1.5 times compared to before the film A was bonded. Further, the organic EL element of Preparation Example 5 in which the film A of Preparation Example 4 and the film B having optical properties similar to each other were bonded together, as in the case of the organic EL element of Preparation Example 4, significantly increased the light extraction efficiency. 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 Transparent support substrate (transparent substrate)
2 Transparent anode (transparent first electrode)
3 Light emitting part 4 Cathode (second electrode)
DESCRIPTION OF SYMBOLS 5 Sealing substrate 6 Layer provided between an anode and a light emitting layer 7 Light emitting layer 8 Layer provided between a cathode and a light emitting layer 9,29 Film 21 Support substrate 22 Anode (2nd electrode)
23 Light Emitting Unit 24 Transparent Cathode (First Electrode)
25 Transparent sealing substrate (transparent substrate)
26 Layer provided between the anode and the light emitting layer 27 Light emitting layer 28 Layer provided between the cathode and the light emitting layer A Film used in Production Example 4 B Film used in Production Example 5 C Used in Comparative Example 1 the film

Claims (11)

A transparent first electrode;
A second electrode having a polarity different from that of the first electrode;
A light emitting layer disposed between the first and second electrodes;
A transparent substrate disposed on a side opposite to the light emitting layer side of the first electrode;
A film disposed on the side opposite to the light emitting layer side of the transparent substrate,
When the refractive index of the first electrode is n1 and the refractive index of the transparent substrate is n2, n1 and n2 are respectively expressed by the following formula (1)

The filling,
An organic electroluminescence device in which the surface of the film opposite to the transparent substrate is formed in an uneven shape, the haze value of the film is 70% or more, and the total light transmittance of the film is 80% or more .   The organic electroluminescence device according to claim 1, wherein the first electrode is formed by a coating method.   3. The organic electroluminescence element according to claim 1, wherein the first electrode includes a transparent film body and a wire-shaped conductor disposed in the film body.   The organic electroluminescent element according to claim 3, wherein the wire-like conductor has a diameter of 200 nm or less.   The organic electroluminescent element according to claim 4, wherein the wire-like conductor forms a network structure in the film main body.   The organic electroluminescent element according to claim 3, wherein the film main body contains a resin having conductivity.   The organic electroluminescent element according to any one of claims 1 to 6, wherein a surface of the film opposite to the transparent substrate side is formed in the uneven shape by arranging a plurality of concave surfaces. It is a manufacturing method of the organic electroluminescent element which manufactures the organic electroluminescent element of any one of Claims 1-7 by providing a 1st electrode, a 2nd electrode, a light emitting layer, a transparent substrate, and a film. ,
In the step of providing the film, a solution containing a material to be the film is applied on the surface of a predetermined base so that the thickness of the film is in a range of 100 μm to 200 μm, and further on the surface of the base The manufacturing method of the organic electroluminescent element which obtains the said film by hold | maintaining the apply | coated solution in the atmosphere whose humidity is 80%-90%, and evaporating the solvent in a solution.   An illuminating device provided with the organic electroluminescent element of any one of Claims 1-7.   A planar light source comprising the organic electroluminescence element according to claim 1.   A display apparatus provided with the organic electroluminescent element of any one of Claims 1-7.

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