JP2010186613A - Organic light-emitting device and method of manufacturing the same, and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic light-emitting device with large light-extraction effect, high efficiency and long life, at low cost. <P>SOLUTION: In the organic light-emitting device, a first electrode, a light-emitting layer, and a second electrode are laminated from a substrate side on the substrate, the second electrode is a transparent electrode, and light is extracted from the transparent electrode. The organic light-emitting device includes a high-refractive index concavo-convex layer structured of a transparent layer made from the same material with the transparent electrode and a plurality of particles with the same or higher refractive index than that of the transparent electrode on a side for extracting light of the transparent electrode, with a surface on the opposite side from the transparent electrode formed irregularly. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an organic light-emitting element that has both low power consumption and long life, a method for manufacturing the same, and a display device using the organic light-emitting element.

  Since the organic light-emitting element is self-luminous, when used in a display device, a backlight is not required, and thus has an advantage of being thin and lightweight. Furthermore, the organic light emitting device has a wide viewing angle and a fast response speed, and is suitable as a moving image display device. In addition, since it has a wide viewing angle and is surface emitting, it is also suitable as a light emitting device such as an illumination. In addition, the organic light emitting device has a structure in which a lower electrode, a carrier transport layer, a light emitting layer, and an upper electrode are laminated. For example, electrons injected from the lower electrode through the electron transport layer into the light emitting layer and positive electrons from the upper electrode. Light is emitted by recombination with holes injected into the light emitting layer through the hole transport layer.

  An organic light emitting device having a top emission structure that extracts emitted light from a transparent upper electrode is known. In the case of this top emission structure, a transparent electrode (upper electrode) used as a light extraction electrode is composed of air that is a light extraction layer. The refractive index is higher than that. Therefore, the intensity of light emitted from the light emitting layer is said to be about 20%, and most of the emitted light is totally reflected at the interface between the transparent electrode and the air layer and guided through the transparent electrode layer. To do. Therefore, in order to realize an organic light emitting device with low power consumption, it is important to reduce the loss due to the waveguide of the organic light emitting device and improve the light extraction efficiency.

  In addition, by increasing the efficiency of the organic light emitting device, it is possible to reduce the current value necessary to obtain a constant luminance. It is known that the lifetime of the organic light emitting element is proportional to the power of the reciprocal of the drive current, and low current driving due to high efficiency leads to a long lifetime of the organic light emitting element.

  In order to solve the problem of improving the light extraction efficiency, Patent Document 1 discloses a structure in which a transparent layer and a light diffusion layer are provided on the light extraction side of a transparent electrode. In Patent Document 1, a resin having a higher refractive index than the organic layer is used as a matrix of the transparent layer and the light diffusion layer. Also disclosed is a structure in which a resin structure is used to form a lens structure or a physically uneven surface as a light diffusing layer to diffuse the light of the organic light emitting device and extract it to the air layer.

JP 2004-296429 A

  An organic light emitting device having a structure having a transparent layer and a light diffusing layer as described in Patent Document 1 can extract more emitted light than an organic light emitting device having no light diffusing layer. However, resin is used for the transparent layer and the light diffusion layer, and the refractive index of the resin is 1.75 at the maximum. Although it has a high refractive index as a resin, it is smaller than indium tin oxide (ITO) or indium zinc oxide (IZO) having a refractive index of about 2.0 used as a transparent electrode. Therefore, since the total reflection angle exists at the transparent electrode / resin interface, the light extraction effect is small. There is a problem.

  In addition, since a light diffusion layer having a lens structure or a concavo-convex structure is formed using a resin, a process for transferring a periodic concavo-convex structure and a new manufacturing apparatus facility are necessary, resulting in a high cost. .

  An object of the present invention is a high-efficiency, long-life organic light-emitting element that has a large light extraction effect by eliminating the total reflection angle between the transparent electrode and the light diffusion layer in a top-emission structure organic light-emitting element that extracts light from a transparent electrode Is intended to be provided at low cost.

  Of the inventions disclosed in this application, the outline of typical ones will be briefly described as follows.

In order to solve the above problems, an organic light-emitting device according to the present invention includes:
In the organic light emitting device in which the first electrode, the light emitting layer, and the second electrode are laminated from the substrate side on the substrate, the second electrode is a transparent electrode, and light is extracted from the transparent electrode.
The transparent electrode is composed of a transparent layer made of the same material as the transparent electrode, and a plurality of particles having a refractive index of not less than 2.5 and not more than 2.5. It has the high refractive index uneven | corrugated layer in which the surface of the other side was formed in unevenness, It is characterized by the above-mentioned.

In addition, a method for producing an organic light emitting device according to the present invention includes:
On the substrate, the first electrode, the light emitting layer, and the second electrode are laminated from the substrate side, the second electrode is a transparent electrode, and a method for manufacturing an organic light emitting device that extracts light from the transparent electrode,
A step of forming a high refractive index concavo-convex layer on the side of the transparent electrode from which light is extracted, the surface opposite to the transparent electrode being uneven;
The step of forming the high refractive index uneven layer includes:
(A) applying a plurality of particles having a refractive index equal to or greater than that of the transparent electrode to the light extraction side of the transparent electrode;
(B) forming a transparent layer of the same material as the transparent electrode so as to cover the particles on the light extraction side of the particles;
It is characterized by including.

  The organic light-emitting device having a top emission structure obtained by the above-described configuration and manufacturing method uses the same material for the transparent electrode and the transparent layer, and the refractive index of the particles is equal to or higher than the refractive index of the transparent electrode. There is no total reflection angle between the high refractive index uneven layer. Moreover, since it has the uneven | corrugated shape formed with particle | grains and the transparent layer, the organic light emitting element with a large light extraction effect to an air layer can be obtained. In addition, since the transparent layer is formed using a material and an apparatus on which a transparent electrode is formed, a step of transferring the concavo-convex structure and a manufacturing apparatus therefor are unnecessary. Therefore, an organic light-emitting device having a large light extraction effect, high efficiency and long life can be obtained at low cost.

  The wavelength of visible light is 400 to 800 nm, the blue emission wavelength used in a normal image display device is about 400 nm or more, and the wavelength of red emission is about 700 nm or less. When the height of the unevenness is 1/10 or less of the wavelength of light, the refractive index changes at a very short distance, and the effect of the unevenness is lost by the same principle that the effect as the refractive index gradient is lost. The effect of unevenness is effective by the square of the size of the unevenness. Accordingly, the height of the unevenness for obtaining the effect of the unevenness needs to be 1/5 or more of the wavelength of light. On the other hand, if the average height is too high, the effect of the refractive index gradient is lost. For this reason, the average height is required to be about 1 or less of the wavelength of light, which is a height at which the light does not recognize the uneven shape at all. Therefore, the height of the unevenness is defined within a range of approximately 50 nm to 800 nm.

  Since the high refractive index uneven layer of the present invention comprises a plurality of particles and a transparent layer, and the transparent layer is formed on the plurality of particles, the uneven shape depends on the particle diameter, the distance between particles, and the film thickness of the transparent layer. It is determined. It is necessary to consider that if the high refractive index uneven layer of the present invention has a flat portion, the light extraction effect is reduced at the flat portion. In order to obtain the light extraction effect to the air layer, the uneven shape of the high refractive index uneven layer is required to have as few flat portions as possible, and to have an uneven shape of about 50 nm to 800 nm.

When the particles are applied on the transparent electrode, the particles form various arrangements. When roughly classified, there are a state where particles are in contact with each other and a state where particles are not in contact with each other.
When the transparent layer is formed with a thin film thickness (for example, smaller than the particle diameter) on the state where the particles are in contact with each other, an uneven layer having a height that is half the particle diameter is formed. In addition, when the transparent layer is formed thick (for example, twice or more of the particle diameter) while the particles are in contact with each other, the uneven shape of the particles is flattened, resulting in an uneven layer having a height of half or less of the particle diameter. .
If a transparent layer is formed on a flat transparent electrode in which the particles are not in contact with each other and the particles are too far apart and no particles are present, the surface becomes flat.

  Considering the above, it is appropriate that the particle diameter is 100 nm or more and 2 μm or less, the inter-particle distance is 1 to 3 times the particle diameter, and the film thickness of the transparent layer is 1 to 2 times the particle diameter.

The concavo-convex shape formed on the high refractive index concavo-convex layer is not limited as long as it has a light extraction effect due to light scattering or a lens-like light condensing effect. A preferable aspect ratio (diameter / height) for obtaining light scattering or a lens-like light condensing effect is preferably 2 (hemispherical shape) or more and an aspect ratio of 10 or less that is not too flat.
The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.
ADVANTAGE OF THE INVENTION According to this invention, the organic light emitting element of the top emission structure with a high light extraction effect can be obtained at low cost. Therefore, an organic light emitting display device using an organic light emitting element, or low power consumption of the organic display device can be realized.

  In addition, according to the present invention, it is possible to reduce the driving current by improving the light extraction efficiency, and it is possible to extend the lifetime of the organic light emitting display device and the organic light emitting lighting device using the organic light emitting element.

It is a cross-sectional schematic block diagram of the organic light emitting element of this invention. It is a cross-sectional schematic block diagram just before forming the transparent layer of the organic light emitting element produced by this invention. It is a cross-sectional schematic block diagram of the part whose distance between the particle | grains of this invention is the same as a particle diameter. It is a cross-sectional schematic block diagram of the part whose distance between the particle | grains of this invention is twice a particle diameter. It is a cross-sectional schematic block diagram of the part whose distance between the particle | grains of this invention is 3 times the particle diameter. It is a cross-sectional schematic block diagram of the pixel of the image display apparatus which has the high refractive index uneven | corrugated layer of this invention.

[Example 1]
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1, 2, 3, 4, and 5.
The structure of the organic light emitting device of this example will be described with reference to FIG. FIG. 1 is a schematic sectional view showing an organic light emitting device of the present invention.

  In the organic light emitting device OLED of this example, a lower electrode 101, a light emitting layer 102, a transparent electrode 103 as an upper electrode, and a high refractive index uneven layer 104 are sequentially laminated on a substrate 100 in this order from the substrate 100 side. The high refractive index concavo-convex layer 104 is composed of a transparent layer 105 and a plurality of particles 106, and the surface opposite to the transparent electrode 103 side has a concavo-convex shape. The organic light emitting device OLED shown in FIG. 1 is an organic light emitting device having a top emission structure in which light is extracted from the transparent electrode 103 that is an upper electrode.

For the substrate 100, for example, a transparent material such as quartz, glass plate, polyester, polymethyl methacrylate, polycarbonate, polysulfone, or other plastic film or sheet is used. The organic light emitting device OLED of the present embodiment has a top emission structure and does not extract light from the substrate 100, and thus is not limited to a transparent material. For example, a substrate obtained by coating a thin metal plate with SiO ₂ (silicon oxide film) may be used.

Next, a method for manufacturing the organic light-emitting element OLED of this example will be described with reference to FIGS.
First, the lower electrode 101 is formed on the substrate 100. As the lower electrode 101, for example, a laminated body of LiF and Al was used. Moreover, it is not necessarily restricted to these materials. Instead of LiF, a material in which a Cs compound, a Ba compound, a Ca compound, or the like, an electron transport material, an alkali metal such as Li or Cs, an alkaline earth metal, or an electron-donating organic material is co-evaporated can be used. The lower electrode 101 is a cathode electrode in the present embodiment, and its formation is made by putting about 10 mg and about 5 mg of Al and LiF raw materials into a Mo sublimation boat, respectively, and first, Al having a film thickness of 100 nm is 10.0 ± 0.05 nm. Vapor deposition was controlled at / sec. Thereafter, LiF having a film thickness of 0.5 nm was vapor-deposited while being controlled at 0.01 ± 0.005 nm / sec. The pattern at this time was formed using a shadow mask.

Next, the light emitting layer 102 is formed on the lower electrode 101. The light emitting layer 102 refers to a layer having at least an electron transport layer, an EML layer, and a hole transport layer in order from the lower electrode 101 side.
For the production of the light emitting layer 102, first, an electron transport layer is formed on the lower electrode 101. As the electron transport layer, an Alq film having a thickness of 20 nm is formed by vacuum deposition. At this time, about 40 mg of the raw material was put on a Mo sublimation board, and the deposition rate was controlled to 0.15 ± 0.05 nm / sec. The pattern at this time was formed using a shadow mask.

Next, an EML layer is formed. In this embodiment, an example in which the EML layer uses blue light emission, green light emission, and red light emission is described, but the emission color is not particularly limited.
In the case of a blue-emitting EML layer, a 40 nm-thick distyrylarylene derivative film (hereinafter abbreviated as DPVBi) is formed by vacuum evaporation. About 40 mg of each DPVBi raw material is put into a Mo sublimation boat, and the vapor deposition rate is controlled to 0.40 ± 0.05 nm / sec.

  In the case of an EML layer that emits green light, a co-deposited film of tris (8-quinolinol) aluminum and quinacridone (hereinafter referred to as Alq and Qc, respectively) having a film thickness of 20 nm is formed by a binary simultaneous vacuum deposition method. Put about 40 mg and about 10 mg of Alq and Qc materials on two Mo sublimation boards respectively, and control the deposition rate to 0.40 ± 0.05 nm / sec and 0.01 ± 0.005 nm / sec, respectively. And deposit. The Alq + Qc co-evaporated film functions as a green light emitting layer.

  In the case of an EML layer that emits red light, a 40 nm-thick Alq and Nile red co-deposited film (hereinafter abbreviated as Nr) is formed by binary simultaneous vacuum deposition. About 10 mg and about 5 mg of Alq and Nr raw materials are put in two Mo sublimation boats, respectively, and the deposition rate is controlled to 0.40 ± 0.05 nm / sec and 0.01 ± 0.005 nm / sec, respectively. Evaporate. The pattern at this time is formed using a shadow mask.

Next, a hole transport layer is formed on the EML layer. The hole transport layer was formed by α-NPD having a thickness of 50 nm by a vacuum deposition method. About 60 mg of α-NPD is put on a Mo sublimation board, and the α-NPD film is formed by controlling the deposition rate to 0.15 ± 0.05 nm / sec. The pattern at this time was formed using a shadow mask.
In this embodiment, an example of forming by the vapor deposition method is described, but the method of forming the light emitting layer 102 is not limited to the vapor deposition method, and the light emitting layer 102 formed by a coating method may be used.

  Next, after forming the light emitting layer 102 on the lower electrode 101, the transparent electrode 103 is formed on the light emitting layer 102 as an upper electrode. For the transparent electrode 103, ITO (Indium Tin Oxide), which is a transparent conductive material having a refractive index of about 2.0, was used. ITO was formed by sputtering. The transparent electrode 103 made of ITO functions as an anode electrode.

Next, the high refractive index uneven layer 104 is formed on the transparent electrode 103. The high refractive index uneven layer 104 includes a transparent layer 105 and a plurality of particles 106.
The feature of the present invention is that the high refractive index irregularity layer 104 uses particles 106 having a refractive index equal to or higher than that of the transparent electrode 103 and the transparent layer 105 made of the same material as the transparent electrode 103.

  As a method for producing the high refractive index uneven layer 104, first, a plurality of particles 106 are applied on the transparent electrode 103. As a method for applying the particles 106, an inkjet method, a printing method, a spray method, or the like can be used. As the solvent, a mixed solvent of polar solvents such as aromatic and alcohol solvents can be used. Of course, polar solvents such as aromatic solvents and alcohols can be used alone. When forming by the inkjet method, the viscosity of the solution (ink) is desirably 1-20 mPa · s. There is no restriction | limiting in particular in the solid content concentration of a solution, What is necessary is just a solid content concentration which can disperse | distribute the some particle | grains 106 on the transparent electrode 103. FIG.

In this embodiment, a method in which a plurality of particles 106 are applied by a spin coating method will be described. As the particles 106, barium titanate (BaTiO ₃ ) having a refractive index of about 2.4 was used. The average particle diameter of BaTiO ₃ is about 100 nm.

BaTiO ₃ and isopropyl alcohol (IPA) are mixed to prepare a coating solution having a solid content of about 4%. The prepared coating solution was vibrated using a stirrer, an ultrasonic vibrator, or a homogenizer to sufficiently disperse the particles. The coating liquid and the substrate 100 formed up to the transparent electrode 103 are transported to a glove box with a dew point of −90 ° C. The coating solution was applied onto the transparent electrode 103 by a spin coating method (rotation speed: 1600 rpm) in the glove box. When the coating solution was dropped on the transparent electrode 103, a 1.2 μm filter was used to remove foreign substances from the particle aggregates.

Next, after applying the plurality of particles 106 to the transparent electrode 103, baking was performed at 70 ° C. for 10 minutes on a hot plate to completely remove the IPA solvent. The substrate 100 coated with the particles 106 is transported to an ITO sputtering apparatus in which the transparent electrode 103 is formed so as not to touch the outside air. A preferable conveying environment is 1 × 10 ⁻⁴ or less.

  Next, the transparent layer 105 is formed. The same ITO as the transparent electrode 103 was used for the transparent layer 105. The transparent layer 105 was formed by an ITO sputtering apparatus used when forming the transparent electrode 103. As the sputtering method, an isotropic sputtering method with multiple scattering of normal sputtered particles was used.

FIG. 2 is a schematic configuration diagram of the substrate 100 immediately before forming the transparent layer 105. A transparent layer 105 having a film thickness of about 150 nm, which can cover the particles 106, was formed on the transparent electrode 103 on which a plurality of particles 106 were dispersed. Since normal ITO sputtering is isotropic, there is multiple scattering of sputtered particles, so that the particles 106 are covered, and the shape of the particles 106 and the uneven shape having a gentle curved surface along the arrangement interval of the particles 106 Can be formed.
The organic light emitting element OLED shown in FIG. 1 was produced by the above production method.
Although the boundary between the transparent electrode 103 and the transparent layer 105 is indicated by a dotted line in FIG. 1, there is no optical and physical boundary because the transparent electrode 103 and the transparent layer 105 are formed of the same material.

Here, there are two types of light generated in the light emitting layer 102, light reaching the particle 106 and light reaching the uneven shape on the surface of the transparent layer 105.
The light that reaches the particle 106 reaches the particle 106 from the transparent electrode 103 to the particle 106 or from the transparent electrode 103 through the transparent layer 105. The light that reaches the particles 106 enters the particles having a higher refractive index than the transparent electrode 103.
When the refractive index of the particle 106 is lower than that of the transparent layer 105, a total reflection angle exists at the interface between the transparent layer 105 and the particle 106, and thus the emitted light of the light emitting layer 102 is extracted in the air layer direction. The effect is reduced. Further, when the refractive index of the particle 106 is higher than 2.5, for example, the difference in the refractive index between the particle 106 and the transparent layer 105 is large, so that the light incident on the particle 106 is confined. The effect of taking out in the air layer direction is reduced. Therefore, the refractive index of the particle 106 is appropriately 2.0 or more and 2.5 or less, which is equivalent to the transparent electrode 103 and the transparent layer 105. 2.5 The following particle refractive index is greater than 2.0, in addition to BaTiO _3, for example, TiO2 (refractive index 2.5), ZnS (refractive index 2.4) include, present them Example The same effect can be obtained even if it is used.

Since the high refractive index uneven layer 104 of this embodiment uses BaTiO ₃ (refractive index 2.4) for the particles 106 and ITO (refractive index 2.0) for the transparent layer 105, the volume of the particles 106 and the transparent layer 105 is reduced. The average refractive index calculated from the ratio is larger than that of the transparent electrode 103. The void 107 shown in FIG. 3 is present, and the refractive index of the void 107 is 1.0, but the volume ratio of the void 107 to the high refractive index uneven layer 104 is small. The rate is larger than that of the transparent electrode 103, and the influence of the air gap 107 on the light extraction effect is small.

  The light emitted from the particles 106 or the light traveling in the air layer direction without contacting the particles 106 reaches the uneven shape on the surface of the high refractive index uneven layer 104 (transparent layer 105). The light that has reached the uneven shape can be extracted to the air layer by the microlens-like condensing effect due to the unevenness having scattering or curved lines due to the uneven shape. As a result, an organic light emitting device OLED having a large light extraction effect and high luminous efficiency can be obtained.

  With respect to the concavo-convex shape of the high refractive index concavo-convex layer 104, the particle diameter B, the interparticle distance (arrangement pitch) A, and the film thickness C of the transparent layer 105 covering the particles 106 shown in FIGS. 3, 4, and 5 are used. State. 3, 4, and 5 are schematic cross-sectional views of the high refractive index uneven layer, and show the uneven state formed by the light extraction side particles 106 of the transparent electrode 103 and the transparent layer 105.

The uneven shape is formed by the shape of the particles 106, the interval A between the particles 106, and the film thickness C of the transparent layer 105 covering the particles 106. It is very difficult to disperse and arrange the particles 106 on the transparent electrode 103 uniformly and at the same interval. As the arrangement of the particles 106 on the transparent electrode 103 obtained by the coating liquid and spin coating method of this embodiment, there are the particle arrangements shown in FIGS. 3, 4, and 5.
FIG. 3 shows a state in which the particles 106 are in close contact with each other, and an interparticle distance A is equal to the particle diameter B (A = B).
FIG. 4 shows a state in which about one particle 106 is left between the particles 106, and an interparticle distance A is about twice as large as the particle diameter B (A = 2B).
FIG. 5 shows a state in which about two particles 106 are left between the particles 106, and the inter-particle distance A is about three times the particle diameter B (A = 3B).

When the transparent layer 105 is formed on the particle 106 shown in FIGS. 3, 4, and 5, the transparent layer 105 forms a shape that follows the shape of the particle 106, and thus the surface opposite to the transparent electrode 103 side is formed. It becomes an uneven shape having a curve.
Since the unevenness of the transparent layer 105 is formed at the interface between the transparent layer 105 and the air layer, the effect of taking out the light of the organic light emitting element OLED to the air layer due to the light scattering due to the unevenness or the condensing effect like a microlens is great. can do.

In order to improve the light extraction effect, the surface of the transparent layer 105 that contacts the air layer must have an uneven shape. In the case where the arrangement of the particles 106 is as shown in FIG. 3 and the ITO used as the transparent layer 105 is formed to be, for example, three times thicker than the particle diameter, the unevenness of the particles 106 is flat because normal ITO sputtering is isotropic. And the light scattering or microlens-like condensing effect is reduced.
Further, when the particle interval A of the particles 106 is larger than three times the particle diameter, for example, when the film thickness of the transparent layer 105 is made thinner than the particle diameter (less than half the particle diameter), the transparent electrode 103 has a flat shape. Accordingly, a flat transparent layer 105 is formed, and light scattering or microlens focusing effect is reduced.

  In order to reduce the flat portion as much as possible even when the particle arrangement state shown in FIGS. 3, 4, and 5 is present, and to obtain light scattering or a microlens focusing effect, the distance A between the particles is The particle arrangement state shown in FIGS. 3, 4, and 5 exists by setting the film thickness of the transparent layer 105 to 1 to 3 times and the transparent layer 105 to 1 to 2 times the particle diameter. However, it is possible to form a concavo-convex shape in which flat portions are reduced as much as possible. The average height of the concavo-convex shape formed in this example was about 80 nm.

  Since the high refractive index uneven layer 104 of the present embodiment uses the same material (ITO) as the transparent electrode 103 for the transparent layer 105, the light from the transparent electrode 103 passes through the particles 106 or directly to the uneven layer. Can be reached. The light that reaches the concavo-convex layer can be taken out into the air layer by the microlens-like light condensing effect because of the light scattering or curved surface due to the concavo-convex shape.

  The luminous efficiency of the organic light emitting device OLED obtained in this example was about 1.6 times higher than that of the organic light emitting device having only the flat transparent electrode 103.

The present invention relates to an organic light emitting device OLED having a top emission structure in which light is extracted from an upper transparent electrode 103, a transparent layer 105 made of the same material as the transparent electrode 103, and a refractive index higher than that of the transparent electrode 103. It has a high refractive index uneven layer 104 composed of a plurality of particles 106 having a high refractive index of 2.5 or less.
With the organic light emitting device OLED having the top emission structure and the manufacturing method of this embodiment, the lost guided light at the transparent electrode 103 can be extracted to the air layer. As a result, a top-emission organic light-emitting element OLED having a high efficiency and a long lifetime can be obtained at low cost. In addition, the organic light emitting element OLED produced in the present invention can be used for active and passive drive organic light emitting display devices, liquid crystal panel backlights, and illumination devices.

[Example 2]
In this embodiment, the materials of the transparent electrode 103 and the transparent layer 105 shown in the first embodiment are different. For the transparent electrode 103 and the transparent electrode 105 of this example, indium zinc oxide (In-Zn-O, hereinafter, IZO) was used. The transparent electrode 103 and the transparent layer 105 are formed by sputtering. Thereafter, an organic light-emitting element OLED was produced in the same procedure as in Example 1 described above. This embodiment has the same effect as that of the first embodiment described above, and the guided light at the transparent electrode 103 that has been lost can be extracted to the air layer. As a result, a top-emission organic light-emitting element OLED having a high efficiency and a long lifetime can be obtained at low cost. In addition, the organic light emitting element OLED produced in the present invention can be used for active and passive drive organic light emitting display devices, liquid crystal panel backlights, and illumination devices.

Example 3
In this embodiment, the materials of the transparent electrode 103 and the transparent layer 105 shown in the first embodiment are different. For the transparent electrode 103 and the transparent electrode 105 of this example, a binary system such as indium germanium oxide was used. The transparent electrode 103 and the transparent layer 105 are formed by sputtering. Thereafter, an organic light-emitting element OLED was produced in the same procedure as in Example 1 described above. This embodiment has the same effect as that of the first embodiment described above, and the guided light at the transparent electrode 103 that has been lost can be extracted to the air layer. As a result, a top-emission organic light-emitting element OLED having a high efficiency and a long lifetime can be obtained at low cost. In addition, the organic light emitting element OLED produced in the present invention can be used for active and passive drive organic light emitting display devices, liquid crystal panel backlights, and illumination devices.

Example 4
In this embodiment, the materials of the transparent electrode 103 and the transparent layer 105 shown in the first embodiment are different. For the transparent electrode 103 and the transparent layer 105 of this example, a ternary system such as indium tin zinc oxide was used. The transparent electrode 103 and the transparent layer 105 are formed by sputtering. Thereafter, an organic light-emitting element OLED was produced in the same procedure as in Example 1 described above. This embodiment has the same effect as that of the first embodiment described above, and the guided light at the transparent electrode 103 that has been lost can be extracted to the air layer. As a result, a top-emission organic light-emitting element OLED having a high efficiency and a long lifetime can be obtained at low cost. In addition, the organic light emitting element OLED produced in the present invention can be used for active and passive drive organic light emitting display devices, liquid crystal panel backlights, and illumination devices.

Example 5
In this embodiment, the material of the particles 106 shown in the first and second embodiments is different. The particles 106 of this example were ITO particles. Thereafter, an organic light-emitting element OLED was produced in the same procedure as in Example 1 described above.
When ITO particles are used as the particles 106, there is no refractive index difference between the ITO particles and the transparent layer 105 and between the ITO particles and the transparent electrode 103, so that the light from the transparent electrode 103 is not totally reflected by the particles, In addition, since the light can travel in the direction of the air layer without being confined within the particles, the light extraction effect is improved.
In this example, an organic light-emitting element OLED having higher efficiency than that of Examples 1 and 2 can be obtained. As a result, a top-emission organic light-emitting element OLED having a high efficiency and a long lifetime can be obtained at low cost. In addition, the organic light emitting element OLED produced in the present invention can be used for active and passive drive organic light emitting display devices, liquid crystal panel backlights, and illumination devices.

Example 6
In this embodiment, an example in which the present invention is applied to an image display device will be described. FIG. 6 is a schematic cross-sectional configuration diagram of a pixel portion of the image display device.
First, a layer 200 including a thin film transistor (hereinafter simply referred to as TFT) is formed over the substrate 100. The layer 200 including a TFT includes an insulating film that covers the surface of the substrate 100, and an insulating film that protects the TFT and the drain and source electrodes of the TFT.

  Next, after the layer 200 including the TFT is formed, the lower electrode 101 is formed. The lower electrode 101 is electrically connected to the drain electrode or the source electrode of the layer 200 including a TFT. Thereafter, a bank layer 201 is formed to cover the end of the lower electrode 101. The bank layer 201 was patterned so as to cover the edge portion of the lower electrode 101. The bank layer 201 is not specified in particular, but various resins such as a polyimide resin and an acrylic resin can be used. In this embodiment, a photosensitive polyimide resin is used. The bank layer 201 can be formed by applying and developing after exposure and development using a predetermined photomask.

  Next, the light emitting layer 102, the transparent electrode 103, and the high refractive index uneven | corrugated layer 104 are formed. The light emitting layer 102 was formed by a method similar to the method shown in Example 1. The transparent electrode 103 on the light emitting layer 102 was formed by the same method as shown in Examples 1, 2, 3, and 4. The high refractive index uneven layer 104 on the transparent electrode 103 was formed by the same method as shown in Examples 1, 2, 3, 4, and 5.

  Since the image display apparatus of this embodiment includes the high refractive index uneven layer 104, an image display apparatus with high efficiency, low power consumption, and long life can be obtained at low cost. The organic light emitting element OLED produced in the present invention can be used for active and passive drive organic light emitting display devices, liquid crystal panel backlights, and lighting devices.

Example 7
This embodiment is different in the sputtering method for forming the transparent layer 105 in the above-described embodiments 1, 2, 3, 4, and 5. The transparent layer 105 of this embodiment is formed by anisotropic sputtering. Unlike isotropic sputtering, anisotropic sputtering is a sputtering method in which multiple scattering of sputtered particles is reduced and straightness is improved. When formed by the anisotropic sputtering method, there is no multiple scattering of the sputtered particles, so that the sputtered particles do not easily enter the gap between the particle 106 and the transparent electrode 103. Therefore, a gap is formed in the gap between the particle 106 and the transparent electrode 103. The volume of this void is larger than the void formed in Examples 1, 2, 3, 4, and 5. The refractive index of this void is 1, and a large refractive index difference is provided between the void and the transparent electrode 103 and the particle 106, so that light can be scattered. The scattered light reaches the uneven shape of the high refractive index uneven layer 104 and can be extracted to the air layer.

  When forming the high refractive index uneven layer 104 by the anisotropic sputtering method of this embodiment, the distance A of the particles 106 is preferably not more than twice the particle diameter B. This is because if the distance between particles is large, the flat portion of the transparent electrode 103 between the particles becomes flat as it is by anisotropic sputtering, and it becomes difficult to form a gentle curved surface. In this example, the solid content concentration of the coating solution prepared when the particles 106 were applied was 6%, and the number of rotations when applying by the spin coating method was 1000 rom. As a result, there were many arrangements in which the interparticle distance A was twice or less.

In the case of using the anisotropic sputtering of this embodiment, since the uneven shape does not become gentle even if the transparent layer 105 is thick, the thickness of the transparent layer 105 is not limited. Since the time required to form the transparent layer 105 is increased when the film thickness of the transparent layer 105 is large, the film thickness of the transparent layer 105 of this example is formed with the same film thickness as the particle diameter.
With the organic light emitting device OLED having the top emission structure and the manufacturing method of this embodiment, the lost guided light at the transparent electrode 103 can be extracted to the air layer. As a result, a top-emission organic light-emitting element OLED having a high efficiency and a long lifetime can be obtained at low cost. In addition, the organic light emitting element OLED produced in the present invention can be used for active and passive drive organic light emitting display devices, liquid crystal panel backlights, and illumination devices.

In Examples 1 to 7 described above, the transparent layer 105 made of the same material as the transparent electrode 103 and the plurality of particles 106 having a refractive index of not less than the transparent electrode 103 and not more than 2.5 on the transparent electrode 103 as the upper electrode. The structure having the high refractive index concavo-convex layer 104 in which the surface opposite to the transparent electrode 103 is formed as concavoconvex has been described. However, if this structure is expressed in another way, the transparent electrode 103 is 1 transparent layer, the transparent layer 105 as a second transparent layer, and a single transparent layer including the first transparent layer (transparent electrode 103), the second transparent layer (transparent layer 105), and a plurality of particles 106. It may be an electrode. The transparent electrode in this case is formed on the first transparent layer (transparent electrode 103) and the first transparent layer, and the refractive index is not less than the refractive index of the first transparent layer and not more than 2.5. A plurality of particles 106, and a second transparent layer (transparent layer 105) formed on the first transparent layer so as to cover the plurality of particles 106 and made of the same material as the first transparent layer. And has a structure in which the surface opposite to the substrate 100 side is uneven.
As mentioned above, the invention made by the present inventor has been specifically described based on the above embodiments. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Of course.

  According to the configuration and the manufacturing method of the present invention, it is possible to obtain an OLED element having a top emission structure in which light is extracted from the upper transparent electrode having a high efficiency and a long lifetime. The long-lived organic light-emitting device obtained by the present invention can be used for display devices such as televisions and various information terminals. It can also be used for backlights of liquid crystal display devices and lighting devices.

DESCRIPTION OF SYMBOLS 100 ... Board | substrate, 101 ... Lower electrode, 102 ... Light emitting layer, 103 ... Transparent electrode, 104 ... High refractive index uneven | corrugated layer, 105 ... Transparent layer, 106 ... Particle, 107 ... Air gap,
200: Layer including TFT, 201: Bank layer, OLED: Organic light emitting element.

Claims (10)

In the organic light emitting device in which the first electrode, the light emitting layer, and the second electrode are laminated from the substrate side on the substrate, the second electrode is a transparent electrode, and light is extracted from the transparent electrode.
The transparent electrode is formed of a transparent layer made of the same material as the transparent electrode, and a plurality of particles having a refractive index equal to or higher than the refractive index of the transparent electrode, and a surface opposite to the transparent electrode An organic light-emitting device comprising a high-refractive index uneven layer formed on an uneven surface. The organic light emitting device according to claim 1,
The organic light-emitting device, wherein the particles are made of the same material as the transparent electrode. The organic light emitting device according to claim 1,
The organic light-emitting device, wherein a refractive index of the particles is not less than a refractive index of the transparent electrode and not more than 2.5. The organic light emitting device according to claim 1,
The particle diameter of the particles is in the range of 100 nm to 2 μm. The organic light emitting device according to claim 1,
The organic light-emitting device, wherein the transparent layer has a film thickness not less than the particle diameter and not more than twice the particle diameter. The organic light emitting device according to claim 1,
The organic light emitting device, wherein the unevenness of the high refractive index unevenness layer is in the range of 50 nm to 800 nm. The organic light emitting device according to claim 1,
The organic light-emitting device characterized in that the concavo-convex aspect ratio (diameter / height) of the high refractive index concavo-convex layer is in the range of 2-10. On the substrate, the first electrode, the light emitting layer, and the second electrode are laminated from the substrate side, the second electrode is a transparent electrode, and a method for manufacturing an organic light emitting device that extracts light from the transparent electrode,
A step of forming a high refractive index concavo-convex layer on the side of the transparent electrode from which light is extracted, the surface opposite to the transparent electrode being uneven;
The step of forming the high refractive index uneven layer includes:
(A) applying a plurality of particles having a refractive index equal to or greater than that of the transparent electrode to the light extraction side of the transparent electrode;
(B) forming a transparent layer of the same material as the transparent electrode so as to cover the particles on the light extraction side of the particles;
A method for manufacturing an organic light-emitting element comprising: In the organic light emitting device in which the first electrode, the light emitting layer, and the second electrode are laminated from the substrate side on the substrate, the second electrode is a transparent electrode, and light is extracted from the transparent electrode.
The transparent electrode is formed on the first transparent layer, the first transparent layer, a plurality of particles having a refractive index equal to or higher than the refractive index of the first transparent layer, and the first transparent layer. It is formed so as to cover the plurality of particles, and is composed of a second transparent layer made of the same material as the first transparent layer, and the surface opposite to the substrate side is uneven. An organic light emitting device characterized.   A display device comprising the organic light-emitting device according to claim 1.

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