Organic light emitting element, light emitting device, display device, imaging device, electronic device, lighting device, and image forming device

Abstract

The present invention relates to an organic light emitting element, a light emitting device, a display device, an imaging device, an electronic device, an illumination device, and an image forming device. The present disclosure provides an organic light emitting element including a first electrode, an organic compound layer, and a second electrode, wherein the organic compound layer includes a charge transport layer, and the charge transport layer includes a first charge transport layer, a second charge transport layer, and a third charge transport layer in this order, and the first charge transport layer, the second charge transport layer, and the third charge transport layer satisfy the following formulae (1) and (2): μ1> μ2> μ3 (1) d1+ d2< d3 (2) In formula (1), μ1, μ2, and μ3 are charge mobilities of the first charge transport layer to the third charge transport layer, and in formula (2), d1, d2, and d3 are layer thicknesses of the first charge transport layer to the third charge transport layer.

Description

Technical Field

[0001] This invention relates to organic light-emitting elements, light-emitting devices, display devices, camera devices, electronic devices, lighting devices, moving bodies, and image forming devices. Background Technology

[0002] In recent years, organic light-emitting elements (also known as organic EL elements or OLEDs) have been developed for use as light sources. Display devices that include red (R) organic light-emitting elements, green (G) organic light-emitting elements, and blue (B) organic light-emitting elements provide full-color display. In particular, in goggle-type display devices used for augmented reality (AR) or virtual reality (VR), pixel miniaturization and multi-pixelation are employed, and further reductions in the power consumption of the display device are required. On the other hand, one known measure to reduce power consumption is to reduce the driving voltage of the organic light-emitting elements.

[0003] Japanese Patent Application Publication No. 2015-122459 (PTL) discloses an organic light-emitting element comprising an organic compound layer, wherein the organic compound layer includes multiple hole transport layers, wherein the hole transport layer having the largest thickness has a higher hole mobility than the other hole transport layers, thereby achieving a reduction in the driving voltage of the organic light-emitting element.

[0004] However, in order to achieve the reduction in driving voltage as described by PTL, the increased hole mobility of the hole transport layer with maximum thickness also causes current to be supplied to adjacent organic light-emitting elements, resulting in unintended light emission. This unintended light emission causes a reduction in the display color gamut of the display device, which is problematic. Summary of the Invention

[0005] The present invention provides an organic light-emitting element, wherein reducing the driving voltage of the organic light-emitting element can reduce unintended light emission in adjacent organic light-emitting elements.

[0006] The organic light-emitting element according to the embodiments of this disclosure provides an organic light-emitting element comprising a first electrode on an insulating layer, a first light-emitting layer on the first electrode, a second electrode on the first light-emitting layer, and a charge transport layer between the first electrode and the first light-emitting layer, wherein the charge transport layer comprises, from the first electrode side, a first charge transport layer, a second charge transport layer, and a third charge transport layer in sequence, and the first charge transport layer, the second charge transport layer, and the third charge transport layer satisfy the following equations (1) and (2):

[0007] μ1 > μ2 > μ3 (1)

[0008] d1 + d2 < d3 (2)

[0009] In equation (1), μ1 is the charge mobility of the first charge transport layer, μ2 is the charge mobility of the second charge transport layer, and μ3 is the charge mobility of the third charge transport layer.

[0010] In equation (2), d1 is the thickness of the first charge transport layer, d2 is the thickness of the second charge transport layer, and d3 is the thickness of the third charge transport layer.

[0011] Further features of the invention will become apparent from the following description of exemplary embodiments, with reference to the accompanying drawings. Attached Figure Description

[0012] Figure 1A This is a plan view of a light-emitting device according to an embodiment of the present invention. Figure 1B for Figure 1A A magnified view of region IB in the image.

[0013] Figure 2A For along Figure 1B A schematic cross-sectional view taken from line IIA-IIA in the diagram. Figure 2B For along Figure 2A A schematic cross-sectional view of the organic light-emitting element section, indicated by the dashed line IIB in the figure.

[0014] Figure 3 This is a schematic cross-sectional view of a light-emitting device according to an embodiment of the present invention.

[0015] Figure 4 This is a schematic cross-sectional view of a light-emitting device according to an embodiment of the present invention.

[0016] Figure 5 This is a schematic diagram of an example of a display device according to an embodiment of the present invention.

[0017] Figure 6A This is a schematic diagram of an example of a camera device according to the implementation plan. Figure 6B This is a schematic diagram of an example of an electronic device according to an embodiment of the present invention.

[0018] Figure 7A This is a schematic diagram of an example of a display device according to an embodiment of the present invention. Figure 7B This is a schematic diagram of another example of a display device according to an embodiment of the present invention.

[0019] Figure 8A This is a schematic diagram of an example of a lighting device according to an embodiment of the present invention. Figure 8B A schematic diagram of a car, used as an example of a moving body according to an embodiment of the present invention.

[0020] Figure 9A and Figure 9BThis is a schematic diagram of an example of a wearable device according to an embodiment of the present invention.

[0021] Figure 10A This is a schematic diagram of an image forming apparatus according to an embodiment of the present invention. Figure 10B and Figure 10C A schematic diagram showing the configuration of multiple light-emitting units of an exposure light source arranged in a long strip-shaped substrate. Detailed Implementation

[0022] According to an embodiment of the present invention, the organic light-emitting element is as follows: the organic light-emitting element includes a first electrode on an insulating layer, a first light-emitting layer on the first electrode, a second electrode on the first light-emitting layer, and a charge transport layer between the first electrode and the first light-emitting layer, wherein the charge transport layer includes a first charge transport layer, a second charge transport layer, and a third charge transport layer sequentially from the first electrode side, and the first charge transport layer, the second charge transport layer, and the third charge transport layer satisfy the following equations (1) and (2):

[0023] μ1 > μ2 > μ3 (1)

[0024] d1 + d2 < d3 (2)

[0025] In equation (1), μ1 is the charge mobility of the first charge transport layer, μ2 is the charge mobility of the second charge transport layer, and μ3 is the charge mobility of the third charge transport layer.

[0026] In equation (2), d1 is the thickness of the first charge transport layer, d2 is the thickness of the second charge transport layer, and d3 is the thickness of the third charge transport layer.

[0027] According to another embodiment of the present invention, the organic light-emitting element is an organic light-emitting element comprising a first electrode, a second electrode, a first light-emitting layer disposed between the first electrode and the second electrode, and a charge transport layer between the first electrode and the first light-emitting layer, wherein the charge transport layer comprises a first charge transport layer, a second charge transport layer having a lower charge mobility than the first charge transport layer, and a third charge transport layer having a lower charge mobility than the first charge transport layer, and the layer thickness of the first charge transport layer is less than the layer thickness of the second charge transport layer and the layer thickness of the third charge transport layer.

[0028] The charge transport layer, the first light-emitting layer, and all organic layers between the first and second electrodes can be collectively referred to as the organic compound layer. This also applies to cases where other organic layers are configured.

[0029] The charge transport layer can be either a hole transport layer or an electron transport layer. When the charge transport layer is a hole transport layer, the charge mobility is equal to the hole mobility; when the charge transport layer is an electron transport layer, the charge mobility is equal to the electron mobility. When the relationship between layer thickness and mobility is satisfied, the leakage current between the organic light-emitting element (OLED) and its adjacent OLEDs can be reduced. OLEDs can also be referred to as sub-pixels in a display device.

[0030] The charge transport layer can be a hole transport layer. This is because organic compounds tend to have hole transport properties, and in such hole transport layers, leakage current tends to be generated between the organic light-emitting element and its adjacent organic light-emitting element.

[0031] According to an embodiment of the present invention, the charge transport layer includes a first charge transport layer, a second charge transport layer, and a third charge transport layer, wherein the charge mobility of the first charge transport layer is lower than that of the second and third charge transport layers. The charge mobility of the second charge transport layer is lower than that of the third charge transport layer.

[0032] The thickness of the first charge transport layer is less than that of the second and third charge transport layers. The thickness of the second charge transport layer can be less than that of the third charge transport layer.

[0033] According to an embodiment of the present invention, a first charge transport layer comprises a first organic compound and a third charge transport layer comprises a third organic compound. A second charge transport layer may be a mixture of the first and third organic compounds.

[0034] The content of the third organic compound relative to the total amount of the first and third organic compounds contained in the second charge transport layer can be 50% by volume or more. The content of the third organic compound relative to the total amount of the first and third organic compounds contained in the second charge transport layer can be 50% by wt% or more. The content of the third organic compound relative to the total amount of the first and third organic compounds contained in the second charge transport layer can be 50% by mol% or more.

[0035] The organic light-emitting element according to an embodiment of the present invention can be used in display devices with a pixel density of 1000 ppi (pixels per inch) or higher. This is because the higher the pixel density, the more likely leakage current is to occur between the organic light-emitting element and its adjacent organic light-emitting elements. Therefore, the advantage of reduced leakage current due to the organic light-emitting element according to this embodiment is significantly provided.

[0036] In the organic light-emitting element according to an embodiment of the present invention, the thickness of the charge transport layer can be less than 20 nm. This is because such a small layer thickness results in low leakage current between such organic light-emitting elements, and such a small layer thickness itself leads to a reduction in leakage current.

[0037] The invention will now be described in more detail with reference to various embodiments. These embodiments are non-limiting examples of the invention. Features described in the embodiments may be combined together.

[0038] First Implementation Plan

[0039] Hereinafter, embodiments of the invention will be described with reference to the accompanying drawings.

[0040] Figure 1A This is a plan view of a light-emitting device according to an embodiment of the present invention. The light-emitting device includes a light-emitting region 1 on a substrate 100, and a plurality of organic light-emitting elements 300 are disposed in the light-emitting region 1.

[0041] In area IB, multiple organic light-emitting elements 300 are configured.

[0042] Figure 1B for Figure 1A An enlarged view of region IB in the image. An organic light-emitting element surrounded by dotted lines 150 constitutes a pixel. This pixel includes multiple sub-pixels 300 configured to emit light of different colors. For example, sub-pixels 300 are configured to emit red (R), green (G), and blue (B) light respectively and constitute a pixel (W) 150. Each sub-pixel 300 includes optical components 190 for extracting light emitted from the light-emitting region of each sub-pixel. Such sub-pixels are separated by a pixel separation layer described later.

[0043] The pixel arrangement of the light-emitting device according to this embodiment has a so-called triangular arrangement; however, the invention is not limited thereto. Optionally, the pixel arrangement may have, for example, a stripe arrangement, a square arrangement, a PenTile arrangement, or a Bayer arrangement. Similarly, the shape of the light-emitting area is not limited to the shape shown, and may be circular, elliptical, or polygonal, such as hexagonal or quadrilateral.

[0044] Figure 2A For along Figure 1B A schematic cross-sectional view taken along line IIA-IIA. The light-emitting region 1 includes a plurality of sub-pixels 300, in this case, the sub-pixels 300 are red sub-pixels 300R, green sub-pixels 300G, and blue sub-pixels 300B. Each sub-pixel 300 includes a first electrode 2 on the insulating layer 100. A pixel separation layer 3 is configured to cover the end of the first electrode 2. The pixel separation layer 3 is also called a bank layer. An organic compound layer including a light-emitting layer is disposed on the first electrode 2 and the pixel separation layer 3. The upper surface of the first electrode 2 includes a first region in contact with the organic compound layer and a second region in contact with the pixel separation layer 3.

[0045] The organic compound layer includes a charge transport layer 4 for transporting holes, a light-emitting layer 5, and an electron transport layer 6. A second electrode 7 is disposed on the organic compound layer. The first electrode 2, the organic compound layer, and the second electrode 7 constitute the organic light-emitting element C.

[0046] The organic compound layer and the second electrode 7 are configured to be shared by the sub-pixels 300. A protective layer 8 for protecting the organic light-emitting element C is disposed on the second electrode 7. The protective layer 8 is also called a sealing layer. A planarization layer 9 is disposed on the protective layer 8. The planarization layer 9 is called a resin layer based on its composition.

[0047] A color filter 180 is disposed on the planarization layer 9. Color filters 180R, 180G, and 180B are disposed to correspond to each sub-pixel 300. A planarization layer 9 is disposed on the color filter 180. The planarization layer 9 and the planarization layer 9 in contact with the protective layer 8 can be separated, or the planarization layers 9 can be in contact with each other at their ends (not shown). The planarization layer 9 in contact with the protective layer 8 and the planarization layer 9 disposed on the color filter can have the same composition or can have different compositions. The planarization layer 9 in contact with the protective layer 8 can be referred to as the first planarization layer. The planarization layer 9 disposed on the color filter 180 can be referred to as the second planarization layer. The planarization layer 9 can also be referred to as the first resin layer and the second resin layer based on the constituent materials.

[0048] On the second planarization layer 9, a lens 190 is disposed as an optical component. The lens 190 includes 190R, 190G and 190B configured to correspond to each sub-pixel 300.

[0049] Figure 2B For the reason Figure 2A A schematic cross-sectional view of the organic light-emitting element portion enclosed by the dashed line IIB.

[0050] On the insulating layer 100, a first electrode 2, a second electrode 7, and an organic compound layer comprising a light-emitting layer 5 disposed between the first electrode 2 and the second electrode 7 are configured. The first electrode 2 can serve as a reflective layer. In this embodiment, the first electrode 2 is an anode and the second electrode 7 is a cathode. In this case, the organic compound layer comprises a charge transport layer 4 for transporting holes, a light-emitting layer 5, and an electron transport layer 6. The charge transport layer 4 comprises a first charge transport layer 401, a second charge transport layer 402, and a third charge transport layer 403.

[0051] An electron extraction layer 400 may be disposed between the first electrode 2 and the charge transport layer 4. The electron extraction layer 400 allows for improved adhesion between the first electrode 2 and the charge transport layer 4 and also improves hole injection. The electron extraction layer 400 has the function of extracting electrons from the first charge transport layer 401 in contact with the electron extraction layer 400, thereby generating holes in the first charge transport layer 401. In this case, electrons extracted from the first charge transport layer 401 are generated in the electron extraction layer 400, and these electrons flow into the first electrode 2.

[0052] The charge transport layer of the organic light-emitting element according to an embodiment of the present invention will be described in more detail. The charge transport layer 4 satisfies the following two conditions: in the charge transport layer 4, the charge mobility of the first charge transport layer is defined as μ1, the charge mobility of the second charge transport layer is defined as μ2, the charge mobility of the third charge transport layer is defined as μ3, and the layer thicknesses of these charge transport layers are defined as d1, d2, and d3, respectively.

[0053] μ1 > μ2 > μ3 (1)

[0054] d1 + d2 < d3 (2)

[0055] For the first charge transport layer, a charge transport material with a higher charge mobility than the materials used in the second and third charge transport layers is selected. From the viewpoint of reducing the driving voltage, the mobility of the charge transport material can be 1.0 × 10⁻⁶. -3 Up to 10 -2 cm 2 / V·s. When using such a material with high charge mobility, the charge injected through the holes of the first electrode is rapidly transported to the second charge transport layer, thereby reducing charge accumulation and suppressing the rise of the driving voltage.

[0056] However, the first charge transport layer is formed of a material with high mobility, and therefore has high mobility not only along the direction from the first electrode to the second electrode, but also along the directions intersecting that direction. Consequently, the charge injected through the first electrode also flows to adjacent organic light-emitting elements, resulting in charge leakage. In the event of charge leakage to adjacent organic light-emitting elements, unintended luminescence occurs in the adjacent organic light-emitting elements, which in turn means that the desired color purity cannot be provided.

[0057] On the other hand, in order to reduce charge leakage, when the first charge transport layer is formed using a material with low mobility, charge leakage to adjacent sub-pixels is reduced, but an increased voltage needs to be applied for light emission.

[0058] Therefore, in the organic light-emitting element according to this embodiment, the first charge transport layer is formed of an organic material with high mobility, and the third charge transport layer is formed of an organic material with a lower mobility than the first charge transport layer. The second charge transport layer is formed of an organic material with a charge mobility between that of the first and third charge transport layers. As a result, the charge transported from the first charge transport layer can be efficiently transported to the third charge transport layer with low mobility. This can be explained based on the Maxwell-Wagner effect. Consider an element comprising a pair of electrodes and two organic materials with different mobilities disposed between the electrodes. When charge is injected into the organic material through one electrode, the change in charge capacity in the dielectric at the interface between layers with large differences in mobility leads to a large difference in current relaxation time (affected by mobility). This, in turn, leads to charge accumulation at the interface. However, the difference in interlayer mobility can be reduced, thereby reducing the difference in current relaxation time and thus reducing charge accumulation at the interface. As a result, the charge injected through the first electrode is effectively transported to the light-emitting layer and the charge accumulation at the interface is reduced, thus making it less likely to cause charge leakage to adjacent organic light-emitting elements.

[0059] On the other hand, the layer thickness of the charge transport layer of the organic light-emitting element according to this embodiment satisfies the equation (2) defined above. For the sole purpose of reducing the driving voltage, a first charge transport layer with high mobility can be formed by maximizing its thickness; however, when the first charge transport layer is formed to its maximum thickness, charge leakage tends to occur. Therefore, the total layer thickness of the first and second charge transport layers can be made smaller than the layer thickness of the third charge transport layer, thereby reducing charge leakage to adjacent organic light-emitting elements while maintaining charge injection through the first electrode.

[0060] Compared to using organic materials with low mobility to form the first charge transport layer to reduce charge leakage, efficient charge transport to the third charge transport layer can be achieved, thereby reducing charge leakage without increasing the driving voltage. This reduction in charge leakage also reduces color mixing caused by unintended emission from adjacent organic light-emitting elements.

[0061] The second charge transport layer can be formed as a mixture of the materials of the first and third charge transport layers. The mixing ratio can be varied to give the second charge transport layer an appropriate charge mobility. For the second charge transport layer, the mixing ratio can be continuously varied or multilayer films with different mixing ratios can be formed.

[0062] An electron extraction layer with an electron affinity EA of 5.0 eV or higher can be inserted between the first electrode and the first charge transport layer. Electron affinity can be measured based on the LUMO (Low Lumen Oxide-Mean-Magnesium). An electron affinity EA of 5.0 eV or higher corresponds to a LUMO below -5.0 eV. For example, tetracyanoquinone dimethane (TCNQ) derivatives or hexaazabenzophenanthrene derivatives (HAT) can be used. Alternatively, inorganic materials such as molybdenum oxide, tungsten oxide, or titanium oxide can be used for the electron extraction layer.

[0063] Second Implementation Plan

[0064] Figure 3 This is a schematic cross-sectional view of the light-emitting device according to this embodiment. In this embodiment, the pixel separation layer 3 is buried in the groove between the first electrodes to form a substantially flat surface. Other configurations are the same as in the first embodiment. Since the substrate surface is substantially flat, short circuits in the organic light-emitting elements caused by unevenness of the substrate surface can be reduced.

[0065] Third Implementation Plan

[0066] Figure 4 This is a schematic cross-sectional view of the light-emitting device according to this embodiment. A reflective layer 700 is formed on the substrate; transparent layers 500 and 600 made of SiO2 are formed on the reflective layer 700; transparent electrodes made of, for example, ITO or IZO are formed on the transparent layers 500 and 600 as first electrodes 2. The first electrode 2 is covered by a pixel separation layer 3 to have an opening. Apart from these features, the organic light-emitting element is configured in the same manner as in the first embodiment.

[0067] In this embodiment, when pixel 300R is, for example, a red pixel, the thicknesses of the organic compound layer, transparent layers 500 and 600, and the first electrode 2 can be adjusted to create optical interference for red. Similarly, when pixels 300G and 300B are green and blue pixels, respectively, an interference design for the emitted color can be provided. Specifically, a first organic light-emitting element and a second organic light-emitting element are disposed on an insulating layer. In the first organic light-emitting element, a reflective layer is disposed between the first electrode and the insulating layer, and a first distance between the reflective layer and the light-emitting layer is set to enhance the light emitted from the light-emitting layer. In the second organic light-emitting element, a reflective layer is disposed between the first electrode and the insulating layer, and a second distance between the reflective layer and the light-emitting layer is set to enhance the light emitted from the light-emitting layer. The first and second distances can be of different lengths.

[0068] Figure 4The arrows in the diagram indicate the optical path length between the reflective layer 700 and the second electrode. The optical path lengths between the reflective layer 700 and the second electrode can each be set to half a wavelength (λ / 2) or a full wavelength (λ) of the desired wavelength. The reflective layer 700 can be electrically connected to the first electrode 2. Similar to the first embodiment, the reflective layer 700 is electrically connected to the circuitry (not shown) of the insulating layer. Alternatively, the reflective layer 700 may not be electrically connected to the circuitry of the insulating layer. In this case, the first electrode can be electrically connected to the circuitry of the insulating layer via, for example, a via.

[0069] In this embodiment, even with white organic light-emitting elements, light from the desired wavelength region of each sub-pixel, which is the extraction target, can be enhanced, thereby improving the color purity of the display panel. High-precision masks can be used to coat each pixel with a light-emitting layer so that it emits only the desired light color, thereby further improving the efficiency of the organic light-emitting element and enhancing color purity.

[0070] Fourth Implementation Plan

[0071] The light-emitting device according to this embodiment includes organic light-emitting elements with a so-called tandem structure, wherein two or more organic light-emitting elements are formed between the first electrode and the second electrode. In this embodiment, similarly to the first embodiment, [the following is a description of the formation process]. Figure 2B The organic light-emitting element is then formed until an electron transport layer is formed. Subsequently, a co-evaporated film of, for example, alkali metal and electron transport material is formed on the electron transport layer 6 to form a so-called n-type doped electron injection layer.

[0072] Subsequently, an electron extraction layer, a charge transport layer, a light-emitting layer, and an electron transport layer are formed again on the electron injection layer 6. In this case, the electron extraction layer serves as a charge generation layer configured to extract electrons from the charge transport layer and inject electrons into the n-type doped electron injection layer on the first electrode side. Furthermore, in this case, by using the charge transport layer according to this embodiment, charge leakage to adjacent pixels in the light-emitting element on the second electrode side can also be reduced.

[0073] Specifically, the light-emitting device according to this embodiment includes an organic light-emitting element comprising a first electrode, a second electrode, and an organic compound layer disposed between the first and second electrodes. The organic compound layer includes a charge transport layer, a light-emitting layer, an electron extraction layer, an upper charge transport layer, a second light-emitting layer, and a second electrode, wherein these layers are arranged in the above-described order from the first electrode side. The LUMO of the organic compound contained in the electron extraction layer is lower than the HOMO of the organic compound contained in the electron extraction layer side region of the upper charge transport layer.

[0074] The upper charge transport layer includes a fourth charge transport layer, a fifth charge transport layer, and a sixth charge transport layer. The fourth, fifth, and sixth charge transport layers satisfy the following two conditions: the charge mobility of the fourth charge transport layer is defined as μ4, the charge mobility of the fifth charge transport layer is defined as μ5, and the charge mobility of the sixth charge transport layer is defined as μ6. The layer thicknesses of these layers are defined as d4, d5, and d6, respectively.

[0075] μ4 > μ5 > μ6 (3)

[0076] d4 + d5 < d6 (4)

[0077] For the fourth charge transport layer, a charge transport material with a higher charge mobility than the materials used for the fifth and sixth charge transport layers is selected. From the viewpoint of reducing the driving voltage, the mobility of the charge transport material can be 1.0 × 10⁻⁶. -3 Up to 10 -2 cm 2 / V·s. This material has such a high charge mobility that the charge injected through the holes of the first electrode is rapidly transported to the second charge transport layer, thereby reducing charge accumulation and suppressing the rise of the driving voltage.

[0078] The upper charge transport layer that satisfies equations (3) and (4) above may have the following structure: a fourth charge transport layer, a fifth charge transport layer having a lower charge mobility than the fourth charge transport layer, and a sixth hole transport layer having a lower charge mobility than the fourth charge transport layer, wherein the layer thickness of the fourth charge transport layer is less than the layer thickness of the fifth charge transport layer and the layer thickness of the sixth hole transport layer.

[0079] In other words, this embodiment includes a first electrode, a second electrode, and an organic compound layer between the first and second electrodes, wherein the organic compound layer includes a first light-emitting unit, a charge-generating section, and a second light-emitting unit. The first light-emitting unit includes a hole transport layer, a light-emitting layer, and an electron transport layer; the second light-emitting unit includes a hole transport layer, a second light-emitting layer, and an electron transport layer. The charge-generating section includes an electron extraction layer.

[0080] In this embodiment, an organic light-emitting element comprising a first light-emitting unit and a second light-emitting unit is described. However, the present invention is not limited to this configuration, and multiple light-emitting units further comprising a third light-emitting unit, etc., may be provided.

[0081] The composition of the organic compound layer of an organic light-emitting element

[0082] The organic compound layer of the organic light-emitting element according to this embodiment will be described below. As long as the organic compound layer of the organic light-emitting element according to this embodiment includes a light-emitting layer, the organic compound layer can be a single layer or a multilayer structure composed of multiple layers. When the organic compound layer is a multilayer structure composed of multiple layers, in addition to the light-emitting layer, the organic compound layer may also include, for example, a hole injection layer, a hole transport layer, an electron blocking layer, a hole-exciton blocking layer, an electron transport layer, or an electron injection layer. The light-emitting layer can be a single layer or a multilayer structure composed of multiple layers.

[0083] In the organic light-emitting element according to this embodiment, at least one of such organic compound layers comprises an organometallic complex according to this embodiment. Specifically, for example, any of the above-described light-emitting layer, hole injection layer, hole transport layer, electron blocking layer, hole-exciton blocking layer, electron transport layer, and electron injection layer comprises an organic compound according to this embodiment. The light-emitting layer may contain an organic compound according to this embodiment.

[0084] In the organic light-emitting element according to this embodiment, when the light-emitting layer contains an organic compound according to this embodiment, the light-emitting layer can be a layer formed solely of the organic compound according to this embodiment, or it can be a layer formed of an organometallic complex according to this embodiment and another compound. In the case where the light-emitting layer is a layer formed of an organometallic complex according to this embodiment and another compound, the organic compound according to this embodiment can be used as the host of the light-emitting layer, as a guest, or as an auxiliary material that can be included in the light-emitting layer. The host can be the compound that constitutes the light-emitting layer in the highest mass proportion. The guest is a compound that constitutes the light-emitting layer in a low mass proportion of the host and mainly contributes to light emission. The auxiliary material is a compound that constitutes the light-emitting layer in a low mass proportion of the host and assists the guest in light emission. Note that the auxiliary material is also called a second host. The host material can also be called a first compound and the auxiliary material can also be called a second compound.

[0085] When an organic compound according to this embodiment is used as a guest in the light-emitting layer, the concentration of the guest relative to the entire light-emitting layer is preferably 0.01% by mass or more and 20% by mass or less, more preferably 0.1% by mass or more and 10% by mass or less.

[0086] Furthermore, depending on the requirements, well-known low-molecular-weight or high-molecular-weight hole-injecting or hole-transporting compounds, compounds used as the host, luminescent compounds, electron-injecting compounds, or electron-transporting compounds may be used. Examples of these compounds will be described below.

[0087] Such hole-injection transport materials can be materials with high hole mobility, thereby facilitating hole injection through the anode and transporting the injected holes to the light-emitting layer. Hole-injection transport materials can also be materials with high glass transition temperatures, thereby suppressing film degradation such as crystallization in organic light-emitting elements. Examples of low-molecular-weight or high-molecular-weight materials with hole-injection transport properties include aromatic amine derivatives, carbazole derivatives, furan derivatives, triarylamine derivatives, arylcarbazole derivatives, phenylenediamine derivatives, violet derivatives, phthalocyanine derivatives, porphyrin derivatives, poly(vinylcarbazole), poly(thiophene), and other conductive polymers. Such hole-injection transport materials can also be used in electron blocking layers.

[0088] The following are examples of compounds that can be used as hole-transporting materials. However, the present invention is not limited to these compounds.

[0089]

[0090]

[0091]

[0092] Among the aforementioned hole-transporting materials, HT19 to HT33 and HT35, which are arylamines having two nitrogen atoms, can be used.

[0093] Examples of luminescent materials that primarily contribute to luminescence include fused-ring compounds (e.g., fluorene derivatives, naphthalene derivatives, pyrene derivatives, perylene derivatives, tetraphenylene derivatives, anthracene derivatives, and rubrene), quinacridone derivatives, coumarin derivatives, zirconia derivatives, organoaluminum complexes such as tris(8-hydroxyquinoline)aluminum, iridium complexes, platinum complexes, rhenium complexes, copper complexes, europium complexes, ruthenium complexes, and polymeric derivatives such as poly(phenylenevinylene) derivatives, poly(fluorene) derivatives, and poly(phenylene) derivatives.

[0094] From the viewpoint of reducing the decrease in luminescence efficiency due to the formation of excimer complexes or the decrease in color purity due to changes in the luminescence spectrum of the luminescent material caused by the formation of excimer complexes, the luminescent material can be a hydrocarbon compound.

[0095] From the perspective of having a high ionization potential and therefore being less likely to be oxidized, luminescent materials can be fused polycyclic compounds including five-membered rings to provide components with high durability and long lifespan.

[0096] Besides aromatic hydrocarbon compounds or their derivatives, examples of the host or auxiliary materials of the luminescent layer included in the luminescent layer include carbazole derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, organoaluminum complexes such as tris(8-hydroxyquinoline)aluminum, and organobryllium complexes.

[0097] From the viewpoint that the compound according to this embodiment becomes more likely to capture electrons or holes and thus greatly improves efficiency, the host material can be a hydrocarbon compound. A hydrocarbon compound is a compound consisting only of carbon and hydrogen.

[0098] Electron-transporting materials can be arbitrarily selected from materials capable of transporting electrons injected through the cathode to the light-emitting layer, and are chosen based on, for example, a balance with the hole mobility of hole-transporting materials. Examples of materials with electron-transporting properties include oxadiazole derivatives, oxazole derivatives, pyrazine derivatives, triazole derivatives, triazine derivatives, quinoline derivatives, quinoxaline derivatives, phenanthroline derivatives, organoaluminum complexes, and fused-ring compounds (e.g., fluorene derivatives, naphthalene derivatives, etc.). (Derivatives and anthracene derivatives). Such electron-transporting materials can also be used in hole-blocking layers.

[0099] Electron-injecting materials can be arbitrarily selected from materials that can be readily injected with electrons through the cathode, and are chosen based on, for example, a balance with hole injection. Examples include n-type dopants and reducing dopants as organic compounds. Examples include compounds containing alkali metals such as lithium fluoride, lithium complexes such as lithium quinolinol, benzoimidazolidene derivatives, imidazolidene derivatives, fulvalene derivatives, and acridine derivatives. Such materials can also be used in conjunction with the aforementioned electron-transporting materials.

[0100] Composition of organic light-emitting elements

[0101] An organic light-emitting element is provided by forming an insulating layer, a first electrode, an organic compound layer, and a second electrode on a substrate. A protective layer, a color filter, or a microlens may be disposed on the cathode, for example.

[0102] In the case of forming a color filter, a planarization layer can be formed between the protective layer and the color filter. The planarization layer can be formed, for example, from an acrylic resin. This also applies to the case of forming a planarization layer between the color filter and the microlens.

[0103] substrate

[0104] The substrate can be, for example, a quartz substrate, a glass substrate, a silicon wafer, a resin substrate, or a metal substrate. Switching elements, such as transistors, or wirings, which can be covered by an insulating layer, can be disposed on the substrate. The insulating layer can be formed of any material, as long as contact holes can be formed to allow wiring to the first electrode and to ensure insulation from unconnected wirings. Examples of materials include resins such as polyimide, silicon oxide, and silicon nitride.

[0105] Within the insulating layer, a driving circuit composed of transistors for driving the organic light-emitting element is configured, and the first electrode and the second electrode are electrically connected to the driving circuit (not shown). An insulating layer 100 is disposed on a substrate. The substrate may be, for example, a glass substrate or a silicon substrate. The insulating layer may be a resin layer disposed on the glass substrate or an oxide film formed on the silicon substrate by oxidizing silicon.

[0106] electrode

[0107] As electrodes, a pair of electrodes can be used. A pair of electrodes can be an anode and a cathode.

[0108] When an electric field is applied along the light-emitting direction of the organic light-emitting element, the electrode at the higher potential is the anode, and the other electrode is the cathode. In other words, the electrode configured to supply holes to the light-emitting layer is the anode, and the electrode configured to supply electrons is the cathode. The electrode provided for each sub-pixel can also be called a sub-pixel electrode.

[0109] The material forming the anode can be a material with the highest possible work function. Examples include elemental metals such as gold, platinum, silver, copper, nickel, palladium, cobalt, selenium, vanadium, and tungsten; mixtures of the aforementioned substances; alloys of the aforementioned substances; and metal oxides such as tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide. Other examples include conductive polymers such as polyaniline, polypyrrole, and polythiophene.

[0110] These electrode materials can be used alone or in combination of two or more. The anode can have a single-layer structure or a multi-layer structure.

[0111] The sub-pixel electrode is formed of a metal with high reflectivity. Specifically, the sub-pixel electrode can be formed of a highly reflective metal, such as Al or Ag, or an alloy thereof. The sub-pixel electrode can be formed as a multilayer structure having layers of high work function metals or metal oxides, such as Ti, TiN, Mo, W, ITO, or IZO. In particular, the opening surface of the pixel separation layer of the reflective electrode layer can be covered with such a high work function metal, thereby reducing surface oxidation of the high reflective metal and lowering the driving voltage of the organic light-emitting element. Even when the surface of the sub-pixel electrode is not covered with a high work function metal, a process of removing the oxide film from the opening surface of the pixel separation layer of the sub-pixel electrode can be performed, and an organic layer can subsequently be formed to thereby reduce the voltage rise of the organic light-emitting element.

[0112] Therefore, the second electrode is formed as a transparent or semi-transparent electrode to provide a structure that extracts light to the side opposite the substrate. The second electrode can be a transparent conductive film formed of, for example, ITO or IZO, or an Ag alloy thin film. The organic compound layer is formed of an organic material containing a luminescent substance and a charge-transporting substance.

[0113] The material forming the second electrode (cathode) can be a material with a low work function. Examples of such materials include alkali metals such as lithium, alkaline earth metals such as calcium, elemental metals such as aluminum, titanium, manganese, silver, lead, and chromium, and mixtures of the aforementioned substances. Other examples include alloys of combinations of these elemental metals, such as magnesium-silver, aluminum-lithium, aluminum-magnesium, silver-copper, and zinc-silver.

[0114] Other examples include metal oxides such as indium tin oxide (ITO). These electrode materials can be used alone or in combination of two or more. The cathode can have a single-layer or multi-layer structure. Silver, as a low-resistance material, can be used as the second electrode material; silver alloys can be used to reduce silver aggregation. The alloy ratio is not limited as long as it reduces silver aggregation. For example, the ratio of silver to other metals can be 1:1 or 3:1.

[0115] The cathode can be formed as a conductive layer of an oxide, such as ITO, to provide a top emitting element, or it can be formed as a reflective electrode, such as aluminum (Al), to provide a bottom emitting element. The cathode is not limited to the above-described forms and can be formed using any other techniques known in the art. Furthermore, at the interface between the electron transport layer and the second electrode, the electron injection layer can be formed from known materials such as low work function metals (Li, Cs, Ca, or Yb) or low work function metal compounds (LiF, CsF, MgF, or NaF). The method of forming the cathode is not limited to a specific method and any method known to those skilled in the art can be used; for example, DC or AC sputtering can be used because it achieves high film coverage and tends to provide reduced resistance.

[0116] In the case of forming a semi-transparent electrode, a metal that allows some incident light to pass through and reflects some light is used. A metal layer with a sufficiently small thickness can be formed to provide a semi-transparent electrode. For example, a silver layer with a thickness of about 10 nm can be formed to provide a semi-transparent electrode.

[0117] Pixel separation layer

[0118] The pixel separation layer is formed from a silicon nitride (SiN) film, a silicon oxynitride (SiON) film, or a silicon oxide (SiO) film formed by chemical vapor deposition (CVD).

[0119] To improve the in-plane resistivity of the organic compound layer, the organic compound layer, particularly the hole transport layer, can be formed with a small layer thickness on the sidewalls of the pixel separation layer. Specifically, the cone angle of the sidewalls of the pixel separation layer or the layer thickness of the pixel separation layer can be increased to increase vignetting during evaporation, thereby providing a small layer thickness on the sidewalls.

[0120] On the other hand, for the pixel separation layer, the sidewall cone angle or the layer thickness of the pixel separation layer can be adjusted to prevent the formation of pores in the protective layer formed thereon. Since the protective layer is formed without pores, the possibility of defects occurring in the protective layer is reduced. This reduced possibility of defects in the protective layer reduces degradation such as the generation of dark spots or poor conductivity of the second electrode, thereby increasing reliability.

[0121] In this embodiment, charge leakage to adjacent pixels can be effectively suppressed even when the sidewall cone angle of the pixel separation layer is not steep. As a result of the inventors' research, it has been found that charge leakage can be sufficiently reduced as long as the cone angle is in the range of 60° to 90°. The layer thickness of the pixel separation layer can be 10 nm to 150 nm. Alternatively, similar advantages are provided even when the pixel electrode is formed alone without a pixel separation layer. However, in this case, from the viewpoint of reducing short circuits in the organic light-emitting element, the pixel electrode can be formed with a layer thickness of less than half the thickness of the organic layer, or the pixel electrode can be formed with a positively tapered end of less than 60°.

[0122] Furthermore, by forming the first electrode as a cathode and the second electrode as an anode, an electron transport material and a charge transport layer that satisfy conditions (1) and (2) and a light-emitting layer on the charge transport layer can be formed, thereby enabling high color gamut and low voltage driving.

[0123] protective layer

[0124] A protective layer can be formed on the second electrode. For example, glass with a desiccant can be bonded to the second electrode to reduce the penetration of substances such as water into the organic compound layer, thereby reducing the occurrence of display defects. In another embodiment, a passivation film such as silicon nitride can be formed on the cathode to reduce the penetration of substances such as water into the organic compound layer. For example, the cathode formed in a vacuum can be transported to another chamber in a vacuum, and a CVD process can be performed to form a silicon nitride film with a thickness of 2 μm as a protective layer. After film formation by CVD, atomic layer deposition (ALD) can be performed to form the protective layer. There are no limitations on the material of the film in the ALD process, and examples include silicon nitride, silicon oxide, and aluminum oxide. A silicon nitride film can be further formed on the film formed by the ALD process by CVD. The thickness of the film formed by the ALD process can be less than that of the film formed by the CVD process. Specifically, the film formed by the ALD process can have a thickness of less than 50% or less than 10% of the thickness of the film formed by the CVD process.

[0125] The protective layer can be formed using the aforementioned transparent inorganic material and can be planarized, for example, by chemical mechanical polishing (CMP).

[0126] Color filters

[0127] A color filter can be disposed on the protective layer. For example, a color filter formed on another substrate according to the dimensions of the organic light-emitting element can be attached to the substrate having the organic light-emitting element. Alternatively, the color filter can be formed on the aforementioned protective layer by patterning using photolithography. The color filter can be formed from a polymer.

[0128] planarization layer

[0129] A planarization layer may be provided between the color filter and the protective layer. The planarization layer is provided to reduce the unevenness of the underlying layer. For this purpose, the planarization layer may also be referred to as a material resin layer. The planarization layer can be formed from low-molecular-weight organic compounds or high-molecular-weight organic compounds, and may be formed from high-molecular-weight organic compounds.

[0130] Such planarization layers can be placed above and below the color filter, and can be the same or different in terms of constituent materials. Specific examples of materials include polyvinyl carbazole resin, polycarbonate resin, polyester resin, ABS resin, acrylic resin, polyimide resin, phenolic resin, epoxy resin, silicone resin, and urea resin.

[0131] microlenses

[0132] Organic light-emitting devices may include optical components, such as microlenses, on their light-emitting side. Microlenses may be formed, for example, from acrylic or epoxy resins. Microlenses can be used to increase the amount of light extracted from the organic light-emitting device and to control the direction of the extracted light. Microlenses may have a hemispherical shape. When a microlens has a hemispherical shape, the tangent in the contact hemisphere extends parallel to the insulating layer, and the point where the tangent meets the hemisphere is the vertex of the microlens. The vertex of the microlens can also be similarly determined in any cross-sectional view. Specifically, in a cross-sectional view, the tangent in the semicircle contacting the microlens extends parallel to the insulating layer, and the point where the tangent meets the semicircle is the vertex of the microlens.

[0133] The midpoint of a microlens can also be defined. Imagine a line segment extending from one end of an arc to the other end of an arc in the cross-section of the microlens; the midpoint of this line segment can be called the midpoint of the microlens. The cross-section used to determine the vertex and midpoint can be a cross-section perpendicular to the insulating layer.

[0134] The microlens includes a first surface with a protrusion and a second surface opposite to the first surface. The second surface can be configured to be closer to the functional layer side than the first surface. To provide this configuration, the microlens needs to be formed on the light-emitting device. When the functional layer is an organic layer, high-temperature processes can be avoided in the manufacturing process. When a configuration is provided in which the second surface is configured to be closer to the functional layer side than the first surface, the glass transition temperature of all organic compounds constituting the organic layer is preferably 100°C or higher, more preferably 130°C or higher.

[0135] Opposing substrate

[0136] A counter substrate may be disposed on the planarization layer. The counter substrate is disposed at a position opposite to the aforementioned substrate, and is therefore called a counter substrate. The material forming the counter substrate may be the same as that of the aforementioned substrate. When the aforementioned substrate is referred to as the first substrate, the counter substrate may be referred to as the second substrate.

[0137] Organic layer

[0138] The organic compound layer (e.g., hole injection layer, hole transport layer, electron blocking layer, light-emitting layer, hole blocking layer, electron transport layer, or electron injection layer) of the organic light-emitting element according to an embodiment of the present invention is formed in the following manner.

[0139] The organic compound layer of the organic light-emitting element according to embodiments of the present invention can be formed by dry methods such as vacuum evaporation, ion plating, sputtering, or plasma methods. Instead of dry methods, wet methods can be used, in which the material is dissolved in a suitable solvent and the layer is formed by known coating methods (e.g., spin coating, dip coating, casting, LB coating, or inkjet coating).

[0140] In cases where layers are formed using methods such as vacuum evaporation or solution coating, the layers are less likely to undergo crystallization and exhibit high stability over time. In cases where a coating method is used to form a film, the solution can be combined with a suitable binder resin to form the film.

[0141] Non-limiting examples of adhesive resins include polyvinylcarbazole resins, polycarbonate resins, polyester resins, ABS resins, acrylic resins, polyimide resins, phenolic resins, epoxy resins, silicone resins, and urea resins.

[0142] These adhesive resins can be used alone as homopolymers or copolymers, or in combination of two or more of them. Furthermore, known additives such as plasticizers, antioxidants, or UV absorbers can be used as needed.

[0143] Pixel circuit

[0144] The light-emitting device may include pixel circuits connected to the light-emitting elements. The pixel circuits may be active matrix circuits configured to independently control the light emission of each of the first and second light-emitting elements. The active matrix circuits may be voltage-programmed circuits or current-programmed circuits. The driving circuit has pixel circuits for each pixel. Such pixel circuits may include light-emitting elements, transistors configured to control the brightness of the light-emitting elements, transistors configured to control the timing of light emission, capacitors configured to maintain the gate voltage of the transistors configured to control the brightness of light emission, and transistors not connected to GND via the light-emitting elements.

[0145] The light-emitting device includes a display area and a surrounding area disposed around the display area. The display area includes pixel circuitry, and the surrounding area includes display control circuitry. The transistors constituting the pixel circuitry may have a lower mobility than the transistors constituting the display control circuitry.

[0146] The current-voltage characteristic of the transistors constituting the pixel circuit can have a slope that is less than that of the current-voltage characteristic of the transistors constituting the display control circuit. The slope of the current-voltage characteristic can be measured based on the so-called Vg-Ig characteristic.

[0147] The transistors that make up the pixel circuit are transistors connected to light-emitting elements such as the first light-emitting element.

[0148] Pixels

[0149] An organic light-emitting device includes multiple pixels. Each pixel includes sub-pixels configured to emit light of different colors from each other. Each sub-pixel may have an emission color such as R, G, and B.

[0150] In this type of pixel, the area also known as the pixel opening is configured to emit light. This area is the same as the first area.

[0151] The size of the pixel aperture can be less than 15μm and greater than 5μm. More specifically, examples of sizes include 11μm, 9.5μm, 7.4μm and 6.4μm.

[0152] The spacing between subpixels can be less than 10μm; specific examples include less than 8μm, less than 7.4μm, less than 6.4μm, or less than 5μm.

[0153] Pixels in a planar image can have well-known arrangements such as stripe arrangements, triangle arrangements, PenTile arrangements, or Bayer arrangements. The planar shape of a subpixel can be any well-known shape, such as a quadrilateral, such as a rectangle or rhombus, or a hexagon. It should be understood that shapes that are not exactly rectangles but approximate rectangles are also considered rectangles. The shape of a subpixel and the pixel arrangement can be combined.

[0154] Application of organic light-emitting elements according to embodiments of the present invention

[0155] The organic light-emitting element according to embodiments of the present invention can be used as a component of a display device or a lighting device, and is also suitable for, for example, an exposure light source of an electrophotographic image forming apparatus, a backlight of a liquid crystal display device, or a light-emitting device in which a white light source is equipped with a color filter.

[0156] The display device may include the following image information processing devices: an image input unit configured to input image information from, for example, an area CCD, a line CCD, or a memory card; an information processing unit configured to process the input information; and a display unit configured to display the input image.

[0157] Camera equipment or inkjet printers can have a display unit with touch panel functionality. The drive type for this touch panel functionality can be infrared, electrostatic capacitive, impedance film, or electromagnetic induction. The type of touch panel is not limited to the above types and can be any known type of touch panel. A display device can be used as the display unit of a multifunction printer.

[0158] Figure 5 This is a schematic diagram of an example of a display device according to this embodiment. The display device 1000 may include a touch panel 1003, a display panel 1005, a frame 1006, a circuit board 1007, and a battery 1008 between an upper cover 1001 and a lower cover 1009. Flexible printed circuits (FPCs) 1002 and 1004 are connected to the touch panel 1003 and the display panel 1005, respectively. Transistors are formed on the circuit board 1007 by printing. When the display device is not a mobile device, the battery 1008 may not be provided. When the display device is a mobile device, the battery 1008 may be provided in other locations.

[0159] The display device according to this embodiment may include a red color filter, a green color filter, and a blue color filter. The red, green, and blue color filters may be arranged in a triangular configuration.

[0160] The display device according to this embodiment can be used as the display unit of a mobile terminal. In this case, the display device can have both display and operation functions. Examples of mobile terminals include mobile phones such as smartphones, tablet computers, and head-mounted displays.

[0161] The display device according to this embodiment can be used as a display unit of a camera device having an optical unit including multiple lenses and an imaging element configured to receive light passing through the optical unit. The camera device may include a display unit configured to display information obtained through the imaging element. The display unit may be an external display unit or a display unit disposed within a viewfinder. The camera device may be a digital camera or a digital video camera.

[0162] Figure 6A This is a schematic diagram of an example of a camera device according to this embodiment. The camera device 1100 may include a viewfinder 1101, a rear display 1102, an operation unit 1103, and a housing 1104. The viewfinder 1101 may include a display device according to this embodiment. In this case, the display device can display not only the image to be captured, but also, for example, environmental information and camera instructions. Examples of environmental information include the intensity of external light, the orientation of external light, the speed of movement of the subject, and the likelihood that the subject is obstructed by an object.

[0163] Since the time frame suitable for capturing images is very short, it is desirable to display information with minimal delay. Therefore, a display device employing an organic light-emitting element according to an embodiment of the present invention can be used because the organic light-emitting element responds at a high speed. Display devices employing organic light-emitting elements are more suitable for such imaging devices that require displaying images at a higher speed than liquid crystal display devices.

[0164] The imaging device 1100 includes an optical unit (not shown). The optical unit includes multiple lenses and is configured to form an image in an imaging element housed within a housing 1104. The relative positions of the multiple lenses can be adjusted to adjust the focus. This operation can also be performed automatically. The imaging device may also be referred to as a photoelectric conversion device. Instead of a sequential imaging mode, the photoelectric conversion device may include imaging modes, such as a mode for detecting differences from previous images and a mode for extracting images from continuously recorded images.

[0165] Figure 6BThis is a schematic diagram of an example of an electronic device according to this embodiment. The electronic device 1200 includes a display unit 1201, an operation unit 1202, and a housing 1203. The housing 1203 may include circuitry, a printed circuit board including the circuitry, a battery, and a communication unit. The operation unit 1202 may be a button or touch panel type sensor unit. The operation unit may, for example, be a liveness detection unit configured to scan a fingerprint for unlocking. Such electronic devices including a communication unit may also be referred to as communication devices. The electronic device may further include a lens and a camera element to thereby have camera functionality. Images captured by the camera function are displayed on the display unit. Examples of electronic devices include smartphones and laptops.

[0166] Figure 7A This is a schematic diagram of an example of a display device according to this embodiment. Figure 7A A display device, such as a television monitor or a PC monitor, is shown. The display device 1300 includes a frame 1301 and a display unit 1302. The display unit 1302 may employ a light-emitting device according to this embodiment.

[0167] The display device includes a support frame 1301 and a base 1303 for the display unit 1302. The base 1303 is not limited to... Figure 7A The form shown in the figure. The bottom of frame 1301 can also be used as a base.

[0168] The frame 1301 and the display unit 1302 can be curved. The radius of curvature can be greater than 5000 mm and less than 6000 mm.

[0169] Figure 7B This is a schematic diagram of another example of a display device according to this embodiment. Figure 7B The display device 1310 is foldable, meaning it can be folded. The display device 1310 includes a first display unit 1311, a second display unit 1312, a housing 1313, and a bending point 1314. The first display unit 1311 and the second display unit 1312 may include a light-emitting device according to this embodiment. The first display unit 1311 and the second display unit 1312 can be designed together as a seamless single display device. The first display unit 1311 and the second display unit 1312 can separate at the bending point. The first display unit 1311 and the second display unit 1312 can each display different images; and the first display unit and the second display unit can jointly display a single image.

[0170] Figure 8AThis is a schematic diagram of an example of a lighting device according to this embodiment. The lighting device 1400 may include a housing 1401, a light source 1402, a circuit board 1403, an optical film 1404, and a light diffusion unit 1405. The light source may include an organic light-emitting element according to this embodiment. An optical filter may be provided to improve the color rendering index of the light source. The light diffusion unit is configured to effectively diffuse light from the light source to deliver light over a wide range, such as for illumination. The optical filter and the light diffusion unit may be provided on the light-emitting side of the lighting device. The lighting device may optionally be equipped with a cover for its outermost part.

[0171] The lighting equipment is, for example, a device configured to provide indoor lighting. The lighting equipment may be configured to emit light of any color from white, daylight, and blue to red. The lighting equipment may include dimming circuitry for dimming.

[0172] The lighting device may include an organic light-emitting element according to an embodiment of the present invention and a power supply circuit connected to the organic light-emitting element. The power supply circuit is configured to convert AC voltage to DC voltage. "White" corresponds to a color temperature of 4200K. "Daylight white" corresponds to a color temperature of 5000K. The lighting device may include a color filter.

[0173] The lighting device according to this embodiment may include a heat dissipation unit. The heat dissipation unit is configured to release heat from inside the device to the outside of the device. The heat dissipation unit is formed of, for example, a metal or liquid silicon having a high specific heat.

[0174] Figure 8B This is a schematic diagram of a car, used as an example of a moving body according to this embodiment. The car includes a taillight, used as an example of a lighting unit. The car 1500 includes, for example, a taillight 1501 that can be configured to illuminate during braking.

[0175] The taillight 1501 may include an organic light-emitting element according to this embodiment. The taillight may include a protective member for protecting the organic EL element. There are no limitations on the material of the protective member, as long as it has relatively high strength and is transparent. The protective member may be formed, for example, from polycarbonate. Polycarbonate may be mixed with, for example, furan dicarboxylic acid derivatives or acrylonitrile derivatives.

[0176] The vehicle 1500 may include a vehicle body 1503 and a window 1502 mounted to the vehicle body 1503. When the window is not used to identify the front and rear of the vehicle, it may be designed as a transparent display. The transparent display may include an organic light-emitting element according to this embodiment. In this case, constituent components of the organic light-emitting element, such as electrodes, are provided as transparent components.

[0177] The mobile body according to this embodiment can be, for example, a ship, an aircraft, or a drone. The mobile body may include a body and an illumination unit disposed on the body. The illumination unit can emit light to indicate the position of the body. The illumination unit includes an organic light-emitting element according to this embodiment.

[0178] refer to Figure 9A The following will describe application examples of the display devices according to the various embodiments. The display devices can be applied as systems such as smart glasses, HMDs, and smart contact lenses. The camera display devices used in such application examples include camera devices configured to perform photoelectric conversion of visible light and display devices configured to emit visible light.

[0179] Figure 9A A pair of glasses 1600 (smart glasses) is shown as an application example. In the glasses 1600, an imaging device 1602 is disposed inside the lens 1601 on the surface side of the lens 1601. Examples of imaging devices include CMOS sensors or SPADs. Furthermore, a display device according to any of the above embodiments is disposed on the back side of the lens 1601.

[0180] The glasses 1600 further include a controller 1603. The controller 1603 serves as a power supply configured to provide power to the camera device 1602 and the display device according to any of the embodiments. The controller 1603 is configured to control the operation of the camera device 1602 and the display device. In the lens 1601, an optical system is formed configured to focus light onto the camera device 1602.

[0181] Figure 9B The diagram shows glasses 1610 (smart glasses) used as an application example. Glasses 1610 includes a controller 1612. The controller 1612 is equipped with... Figure 9A The imaging device 1602 is equivalent to an imaging device and a display device. An optical system is formed in the lens 1611 to project light from the imaging device and display device within the controller 1612, and to project an image onto the lens 1611. The controller 1612 serves as a power supply configured to provide power to the imaging device and display device and to control the operation of the imaging device and display device. The controller may include a gaze detection unit configured to detect the wearer's gaze. Gaze can be detected using infrared illumination. An infrared emitting unit emits infrared light to the eyeball of a user gazing at the displayed image. The emitted infrared light is reflected by the eyeball, and the reflected light is detected by the imaging unit, which includes a light receiving element, to provide a captured image of the eyeball. A reduction unit is configured to reduce the light from the infrared emitting unit to the display unit in a planar view to reduce image quality degradation.

[0182] The user's gaze at a displayed image is detected using a captured image of the eye obtained by capturing infrared light. Known methods are applicable for gaze detection using captured images of the eye. For example, gaze detection methods based on Purkinje images obtained due to the reflection of incident light on the cornea are available.

[0183] More specifically, the pupillary-corneal reflex method is used for gaze detection. Based on the pupil image and Purkinje image included in the captured image of the eye, the pupillary-corneal reflex method is used to calculate the gaze vector representing the orientation (rotation angle) of the eyeball, thereby detecting the user's gaze.

[0184] The display device according to an embodiment of the present invention includes a camera device having a light receiving element, and the display image of the display device can be controlled based on the gaze data of the user from the camera device.

[0185] Specifically, the display device determines a first visual field area and a second visual field area outside the first visual field area based on gaze data. The first and second visual field areas can be determined by the display device's controller or based on determination results received from an external controller. Within the display area of ​​the display device, the display resolution of the first visual field area can be controlled to be higher than that of the second visual field area. In other words, the resolution of the second visual field area can be controlled to be lower than that of the first visual field area.

[0186] The display area includes a first display area and a second display area different from the first display area. A higher-priority area is determined based on viewing data from both the first and second display areas. The first and second display areas can be determined by the display device's controller or based on a determination result received from an external controller. The resolution of the higher-priority area can be controlled to be higher than the resolution of all areas outside the higher-priority area. In other words, the resolution of the lower-priority area can be controlled to be lower than the resolution of the higher-priority area.

[0187] Note that the primary or high-priority visual field can be determined using AI. The AI ​​can be a model configured to infer the angle of the gaze direction and the distance to the target from an image of the eye, based on supervised data showing the actual gaze direction within that image. The AI ​​program can be stored on a display device, camera device, or external device. When the AI ​​program is stored on an external device, it is transmitted to the display device via communication.

[0188] In the case of display control based on visual recognition, the display device can be applied to smart glasses that also include a camera device configured to capture external images. The smart glasses are configured to display the captured external data in real time.

[0189] Figures 10A to 10C An image forming apparatus according to an embodiment of the present invention is shown. Figure 10A This is a schematic diagram of an image forming apparatus 40 according to an embodiment of the present invention. The image forming apparatus includes a photoreceptor, an exposure light source, a developing unit, a charging unit, a transfer unit, a transport roller, and a fixing unit.

[0190] Light 29 is emitted from an exposure light source 28 to form an electrostatic latent image on the surface of a photoreceptor 27. The exposure light source includes an organic light-emitting element according to an embodiment of the invention. The developing unit 31 contains toner, etc. The charging unit 30 charges the photoreceptor. The transfer unit 32 transfers the developed image onto a recording medium 34. The transport unit 33 transports the recording medium 34. The recording medium 34 is, for example, paper. The fixing unit 35 fixes the image formed on the recording medium.

[0191] Figure 10B and Figure 10C This is a schematic diagram showing the configuration of multiple light-emitting units 36 in the exposure light source 28 arranged on a long strip-shaped substrate. Direction 37 is parallel to the axis of the photoreceptor and is the column direction of the organic light-emitting elements. This column direction is the same as the direction of the axis around which the photoreceptor 27 rotates. This direction can also be referred to as the long axis direction of the photoreceptor.

[0192] Figure 10B This illustrates the structure in which the light-emitting units are arranged along the long axis of the photoreceptor. Figure 10B different, Figure 10C The diagram shows a structure in which the light-emitting units in the first and second columns are staggered along the column direction. The first and second columns are arranged at different positions along the row direction.

[0193] In the first column, multiple light-emitting units are arranged at intervals. The second column includes light-emitting units at positions corresponding to the intervals between the light-emitting units in the first column. Therefore, multiple light-emitting units are also arranged at intervals along the row direction.

[0194] Figure 10C The configuration in the diagram can also be referred to as, for example, grid pattern, staggered check pattern, or checkered pattern.

[0195] As described above, the device employing the organic light-emitting element according to this embodiment enables the stable display of high-quality images over a long period of time.

[0196] Example

[0197] Example 1

[0198] Production and evaluation of organic light-emitting elements according to the first embodiment. For example... Figure 2A As shown, a first electrode is formed on an insulating layer by patterning, and a pixel separation layer is formed. The pixel separation layer is formed from a silicon oxide film. The pixel separation layer is formed with a layer thickness of 60 nm. The pixel separation layer is formed such that the sidewall cone angles on the pixel aperture side and the inter-pixel side are approximately 60°. The pixel arrangement is formed as a triangular arrangement in which the inter-pixel aperture distance is set to 1.4 μm and the inter-electrode distance of the first electrode is set to 0.6 μm. The substrate is cleaned, dried, and then transported to a vacuum deposition apparatus; a surface pretreatment process is performed on the substrate in the pretreatment chamber using ultraviolet irradiation or plasma; subsequently, while maintaining a vacuum, the substrate is transported to an evaporation chamber and the following processes are performed.

[0199] On the substrate, an electron extraction layer with a thickness of 8 nm is formed using the following compound 1.

[0200]

[0201] Compound 1

[0202] Subsequently, a first charge transport layer, a second charge transport layer, and a third charge transport layer are formed. Each layer is formed using a charge transport layer material such that the layer thicknesses are as described in Table 2.

[0203] Table 1 shows the hole mobility of HT39 and HT27 and the hole mobility of the HT39:HT27 mixed layer with varying mixing ratio (volume ratio).

[0204] Table 1

[0205] HT39 100:0 5E-3 HT39:HT27 85:15 4E-3 HT39:HT27 70:30 3E-3 HT39:HT27 50:50 2E-3 HT39:HT27 25:75 1E-3 HT39:HT27 15:85 5E-4 HT27 0:100 4E-4

[0206] For the first luminescent layer, a pyrene derivative (compound 2) used as the host material and a green dopant (compound 3) and a red dopant (compound 4) used as luminescent dopants are co-deposited at a weight ratio of 2% and 0.2% to form a layer with a thickness of 10 nm.

[0207]

[0208] For the second emitting layer, the host (compound 2) and the blue emitting dopant (compound 5) were co-deposited to form a layer. Co-deposition was performed to achieve a blue emitting dopant to host weight ratio of 1.5% and a layer thickness of 10 nm. Subsequently, an electron transport layer (compound 6) was formed to a thickness of 40 nm. Then, an electron injection layer was formed using LiF to a thickness of 0.5 nm; subsequently, as the second electrode, a 10 nm thick film was formed using a MgAg alloy containing Mg and Ag in a 1:1 ratio. Finally, as a protective layer, a 1.5 μm thick SiN film was formed by CVD.

[0209]

[0210] After the protective layer is formed, such as Figure 2A As shown, color filters and microlenses as optical components are formed on each sub-pixel to produce organic light-emitting elements.

[0211] For the red, green, and blue pixels of the organic light-emitting element, the EL characteristics of each sub-pixel are evaluated. For the evaluation items, a low brightness (10 cd / m²) is used. 2 The color gamut during the display of a white screen and at high brightness (500 cd / m²) 2 The voltage required to display a white screen. The results will be recorded in Table 2.

[0212] Table 2

[0213]

[0214] Table 2 (continued)

[0215]

[0216] The results show that in the element configurations D100 to D104 that satisfy equations (1) and (2) in the charge transport layer, the color gamut is over 80% and the driving voltage is approximately 4V; compared to comparative examples D105 to D113, a high color gamut is achieved and the driving voltage is reduced. Comparative examples D105, D106, D111, and D113 do not satisfy equations (1) and (2). D107 to D109 are comparative examples that satisfy equation (1) but not equation (2). D110 and D112 are comparative examples that satisfy equation (2) but not equation (1).

[0217] Example 2

[0218] Except for the D100 configuration in Example 1, which uses only HT10 (hole mobility: 1E-3cm) 2 Apart from forming the second charge transport layer ( / Vs), the organic light-emitting element was produced and evaluated in the same manner as in Example 1. This embodiment, satisfying conditions 1 and 2, provides a 90% color gamut and a voltage of 4.0V; thus, high color gamut and low driving voltage are confirmed.

[0219] Example 3

[0220] An organic light-emitting element according to the second embodiment was produced. As an organic light-emitting element, D100 according to the first embodiment was produced and evaluated in the same manner as in Example 1. This embodiment satisfies conditions 1 and 2. The color gamut is 80% and the voltage is 4.0V; thus, high color gamut and low driving voltage are confirmed.

[0221] Example 4

[0222] An organic light-emitting element is manufactured such that, in a first embodiment, the first electrode is the cathode and the second electrode is the anode. An electron injection layer of 0.5 nm thickness, formed of CsF, is formed on the first electrode. As a first charge transport layer, a layer with a thickness of 3E-4 cm⁻¹ is formed. 2 A high-mobility electron transport layer of red phenanthrene (Bphen) with a thickness of 2 nm and a mobility of approximately 1E-7 cm⁻¹ was then formed. 2 / Vs of Alq3 mixture and used to form a migration of 1E-5cm by co-evaporation. 2 A second charge transport layer with a thickness of 5 nm and a density of / Vs is formed. Subsequently, a third charge transport layer with a thickness of 10 nm, formed of Alq3, is formed. Similar to the first embodiment, the first, second, and third charge transport layers satisfy Equations 1 and 2. Then, as light-emitting layers, a second light-emitting layer with a thickness of 10 nm and a first light-emitting layer with a thickness of 10 nm, as in Example 1, are formed sequentially. Subsequently, as hole transport layers, a layer with a thickness of 10 nm, formed of HT27, and a layer with a thickness of 20 nm, formed of HT39, are formed. Subsequently, as an electron extraction layer, a layer with a thickness of 10 nm, formed of HAT-CN, is formed. Finally, as an anode, a layer with a thickness of 10 nm, formed of MgAg(1:1), is formed; subsequently, as a protective layer, a SiN film with a thickness of 1.5 μm is formed by CVD. After forming the protective layer, as... Figure 2A As shown, color filters and microlenses as optical components are formed on each sub-pixel to produce organic light-emitting elements.

[0223] The organic light-emitting element was evaluated in the same manner as in Example 1. The color gamut was 80% and the driving voltage was 5.0V; thus, the high color gamut and low driving voltage were confirmed.

[0224] As described above, a device including an organic light-emitting element according to an embodiment provides a display panel that provides a high color gamut and high quality and operates with low driving voltage and low power consumption.

[0225] The present invention can provide an organic light-emitting element that reduces the driving voltage of the organic light-emitting element and reduces unintended luminescence of adjacent organic light-emitting elements.

[0226] While the invention has been described with reference to exemplary embodiments, it should be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the appended claims is to be accorded the broadest interpretation, thus covering all such modifications and equivalent structures and functions.

Claims

1. An organic light-emitting element, comprising: A first electrode on an insulating layer, a first light-emitting layer on the first electrode, and a second electrode on the first light-emitting layer; and Hole transport layer between the first electrode and the first light-emitting layer The hole transport layer is characterized in that, starting from the first electrode side, it sequentially comprises a first hole transport layer, a second hole transport layer, and a third hole transport layer. The first hole transport layer, the second hole transport layer, and the third hole transport layer satisfy the following equations (1) and (2): μ1 > μ2 > μ3(1) d1 + d2 < d3(2) In equation (1), μ1 is the hole mobility of the first hole transport layer, μ2 is the hole mobility of the second hole transport layer, and μ3 is the hole mobility of the third hole transport layer. In equation (2), d1 is the thickness of the first hole transport layer, d2 is the thickness of the second hole transport layer, and d3 is the thickness of the third hole transport layer.

2. The organic light-emitting element according to claim 1, wherein the thickness of the second hole transport layer is greater than the thickness of the first hole transport layer.

3. The organic light-emitting element according to claim 1, wherein the first hole transport layer comprises a first organic compound and the third hole transport layer comprises a third organic compound, and The second hole transport layer is a layer containing a mixture of the first organic compound and the third organic compound.

4. The organic light-emitting element according to claim 3, wherein the content of the third organic compound is 50% by volume or more relative to the total amount of the first organic compound and the third organic compound in the second hole transport layer.

5. The organic light-emitting element according to claim 1, further comprising, in sequence between the first light-emitting layer and the second electrode, an electron extraction layer, a fourth hole transport layer, a fifth hole transport layer, a sixth hole transport layer, and a second light-emitting layer. The fourth hole transport layer, the fifth hole transport layer, and the sixth hole transport layer satisfy the following equations (3) and (4): μ4 > μ5 > μ6(3) d4 + d5 < d6(4) in, In equation (3), μ4 is the hole mobility of the fourth hole transport layer, μ5 is the hole mobility of the fifth hole transport layer, and μ6 is the hole mobility of the sixth hole transport layer. In equation (4), d4 is the layer thickness of the fourth hole transport layer, d5 is the layer thickness of the fifth hole transport layer, and d6 is the layer thickness of the sixth hole transport layer.

6. The organic light-emitting element according to claim 1, wherein the thickness of the hole transport layer is less than 20 nm.

7. The organic light-emitting element according to claim 1, further comprising a reflective layer between the insulating layer and the first electrode. The first distance between the reflective layer and the first light-emitting layer is set to enhance the light emitted from the first light-emitting layer.

8. A light-emitting device, comprising: The organic light-emitting element is a first organic light-emitting element according to claim 7, and the second organic light-emitting element is different from the first organic light-emitting element. The second organic light-emitting element is an organic light-emitting element comprising a first electrode on an insulating layer, a reflective layer between the insulating layer and the first electrode, a first light-emitting layer on the first electrode, and a second electrode on the first light-emitting layer. In the second organic light-emitting element, a second distance between the reflective layer and the first light-emitting layer is set to enhance the light emitted from the first light-emitting layer of the second organic light-emitting element, and wherein the first distance is different from the second distance.

9. The light-emitting device according to claim 8, wherein the wavelengths of the light emitted by the first light-emitting layer of the first organic light-emitting element and the first light-emitting layer of the second organic light-emitting element are different.

10. The light-emitting device according to claim 8, wherein the hole transport layer extends continuously from the first organic light-emitting element to the second organic light-emitting element.

11. The light-emitting device according to claim 8, comprising a plurality of organic light-emitting elements including the first organic light-emitting element and the second organic light-emitting element. The plurality of organic light-emitting elements are arranged at a density of 1000 ppi or higher, where ppi is the number of pixels per inch.

12. A display device comprising a plurality of pixels, wherein at least one of the plurality of pixels comprises an organic light-emitting element according to any one of claims 1-7 and a transistor connected to the organic light-emitting element.

13. A camera device, comprising: The device includes an optical unit comprising multiple lenses, an imaging element configured to receive light passing through the optical unit, and a display unit configured to display an image captured by the imaging element. The display unit is characterized in that it comprises an organic light-emitting element according to any one of claims 1-7.

14. An electronic device, characterized in that, It includes: The display unit includes an organic light-emitting element according to any one of claims 1-7, a housing including the display unit, and a communication unit disposed in the housing and configured to communicate with an external device.

15. A lighting device, characterized in that, It includes: The light source includes an organic light-emitting element according to any one of claims 1-7, and a light-diffusing unit or optical film configured to allow light emitted from the light source to pass through.

16. A mobile body, characterized in that, It includes: The invention includes an illumination unit with an organic light-emitting element according to any one of claims 1-7 and a body provided with the illumination unit.

17. An image forming apparatus, characterized in that, It includes a photoreceptor and an exposure light source configured to expose the photoreceptor, wherein the exposure light source includes an organic light-emitting element according to any one of claims 1-7.

18. An organic light-emitting element, comprising: A first electrode, a second electrode, a first light-emitting layer disposed between the first electrode and the second electrode, and Hole transport layer between the first electrode and the first light-emitting layer The hole transport layer is characterized in that it comprises a first hole transport layer, a second hole transport layer having a lower hole mobility than the first hole transport layer, and a third hole transport layer having a lower hole mobility than the first hole transport layer. The first hole transport layer, the second hole transport layer, and the third hole transport layer are arranged sequentially from the first electrode side, and The thickness of the first hole transport layer is less than the thickness of the second hole transport layer and the thickness of the third hole transport layer.

19. The organic light-emitting element of claim 18, wherein the first hole transport layer is disposed between the first electrode and the second hole transport layer, and The third hole transport layer is disposed between the second hole transport layer and the first light-emitting layer.

20. The organic light-emitting element according to claim 18, The organic light-emitting element further includes an electron extraction layer and a second light-emitting layer sequentially between the first light-emitting layer and the second electrode, and The organic light-emitting element further includes a fourth hole transport layer, a fifth hole transport layer having a lower hole mobility than the fourth hole transport layer, and a sixth hole transport layer having a lower hole mobility than the fifth hole transport layer, between the electron extraction layer and the second light-emitting layer. The thickness of the fourth hole transport layer is less than that of the fifth hole transport layer and the sixth hole transport layer.

21. A display device comprising a plurality of pixels, characterized in that, At least one of the plurality of pixels includes an organic light-emitting element according to any one of claims 18-20 and a transistor connected to the organic light-emitting element.

22. A camera device, comprising: The device includes an optical unit comprising multiple lenses, an imaging element configured to receive light passing through the optical unit, and a display unit configured to display an image captured by the imaging element. The display unit is characterized in that it comprises an organic light-emitting element according to any one of claims 18-20.

23. An electronic device, characterized in that, It includes: The display unit includes an organic light-emitting element according to any one of claims 18-20, a housing including the display unit, and a communication unit disposed in the housing and configured to communicate with an external device.

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