Self-light-emitting element, method for manufacturing self-light-emitting element, and self-light-emitting display panel, self-light-emitting display device, and electronic device

Abstract

A self-light-emitting element which is provided with a light-emitting layer (17) between a pixel electrode (anode) (13) and a counter electrode (cathode) (20), includes: a first functional layer (18) provided between the light-emitting layer (17) and the counter electrode (20) and containing a fluoride of a metal selected from alkali metals, alkaline earth metals, or rare earth metals; and a second functional layer (19) provided between the first functional layer (18) and the counter electrode (20) and containing a rare earth metal as a dopant.

Description

TECHNICAL FIELD

[0001] The present application relates to a self-light-emitting element such as an organic electroluminescent element (hereinafter referred to as "organic EL element"), a manufacturing method thereof, a self-light-emitting display panel in which the self-light-emitting element is arranged in a matrix form on a substrate, a self-light-emitting display device in which the self-light-emitting display panel is used as an image display portion, and an electronic device. BACKGROUND

[0002] In recent years, as a self-light-emitting display, an organic EL display panel in which a plurality of organic EL elements are arranged in a matrix direction on a substrate has been put into practical use as a display of an electronic device.

[0003] Each organic EL element is a current-driven self-light-emitting element having a basic structure in which an organic light-emitting layer (hereinafter referred to simply as "light-emitting layer") containing an organic light-emitting material is arranged between a pair of electrodes including an anode and a cathode, and light is generated by recombination of holes injected from the anode into the light-emitting layer and electrons injected from the cathode into the light-emitting layer at the time of driving.

[0004] Generally, in such an organic EL display panel, in order to improve the injection property of electrons injected from the cathode into the light-emitting layer, an electron transport layer is provided between the cathode and the light-emitting layer. As the electron transport layer, for example, a configuration in which a compound containing an alkali metal and an alkaline earth metal (hereinafter referred to as "alkali metal or the like") is contained in an organic layer is disclosed in Patent Document 1.

[0005] Such an alkali metal or the like has a low work function and a high ability to inject and transport electrons from the cathode, and thus, it is possible to improve the light-emitting efficiency of the organic EL element.

[0006] In addition, in the above-described Patent Document 1, a buffer layer is provided between the electron transport layer and the light-emitting layer in order to prevent the alkali metal or the like in the electron transport layer from diffusing into the light-emitting layer due to high temperature and further causing deterioration of light-emitting characteristics. The buffer layer is configured of an organic compound such as Alq3, 4,4'-N,N'-dicarbazole-biphenyl (CBP), diphenylstyrylarene (DSA), DPB, BAlq, or an anthracene derivative compound Ir.

[0007] PRIOR ART DOCUMENTS

[0008] PATENT DOCUMENT

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2009-94456 SUMMARY

[0010] PROBLEMS TO BE SOLVED BY THE INVENTION

[0011] However, the functional layer, particularly the organic functional layer, which is the main functional layer of the light emitting layer, has a property of easily absorbing and permeating moisture. On the other hand, there is a problem that the alkali metal or the like contained in the electron transport layer is highly active, rapidly reacts with moisture contained in the functional layer, deteriorates, causes degradation of the electron injection property, and shortens the organic EL display panel.

[0012] In particular, recently, from the viewpoint of manufacturing cost, a wet process (wet method) is used, that is, a functional layer is formed using a printing device or the like to apply a solution (hereinafter referred to as "ink") in which a material having a specific function (functional material: not only including an organic material, but also including an inorganic material.) is dissolved or dispersed in a solvent, in which case, the amount of moisture remaining in the functional layer is much larger than that when the film is formed by a dry process (dry method) such as an evaporation method. In the configuration of the above Patent Document 1, since the buffer layer is composed of an organic compound, moisture in the organic layer of the lower layer can penetrate through the buffer layer to the electron transport layer, and react with the alkali metal or the like in the electron transport layer, thereby causing degradation of the light emitting property.

[0013] The present disclosure was achieved in view of the problems as described above, and aims to provide a self-light-emitting element and a manufacturing method thereof, a self-light-emitting display panel in which the self-light-emitting element is arranged in a matrix on a substrate, a self-light-emitting display device in which the self-light-emitting display panel is used as an image display portion, and an electronic device, which are capable of ensuring good light emitting efficiency while reducing manufacturing cost, and can extend the service life.

[0014] Technical solution for solving the problem

[0015] The self-light-emitting element in one aspect of the present disclosure is provided between an anode and a cathode, and is characterized by including: a first functional layer provided between the light emitting layer and the cathode, and containing a fluoride of a metal selected from an alkali metal, an alkaline earth metal, or a rare earth metal; and a second functional layer provided between the first functional layer and the cathode, and containing a rare earth metal as a dopant material.

[0016] Further, the manufacturing method of the self-light-emitting element in another aspect of the present disclosure is characterized by including: a first step of forming an anode; a second step of forming a light emitting layer above the anode; a third step of forming a first functional layer containing a fluoride of a metal selected from an alkali metal, an alkaline earth metal, or a rare earth metal, on the light emitting layer; a fourth step of forming a second functional layer using a rare earth metal as a dopant material, on the first functional layer; and a fifth step of forming a cathode above the second functional layer.

[0017] Effects of the invention

[0018] According to the self-light emitting element and the manufacturing method of the self-light emitting element in the above-described aspect, a self-light emitting element, a self-light emitting display panel, a self-light emitting display device, and an electronic device can be provided, the self-light emitting element is formed by using a wet process to form at least one functional layer, good light emitting efficiency is ensured while reducing manufacturing costs, and the service life can be extended. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a block diagram showing the overall configuration of an organic EL display device in the aspect of the present disclosure.

[0020] Figure 2 is a schematic plan view showing a part of the image display surface of the organic EL panel in the above-described organic EL display device.

[0021] Figure 3 (a) is a schematic cross-sectional view along the A-A line of Figure 2 (b) is an enlarged view of the inside of the dotted circle C of (a).

[0022] Figure 4 (a) to (e) are partial cross-sectional views schematically showing the manufacturing process of an organic EL element.

[0023] Figure 5 (a) to (d) are partial cross-sectional views schematically showing the manufacturing process of an organic EL element. Figure 4

[0024] Figure 6 (a) and (b) are partial cross-sectional views schematically showing the manufacturing process of an organic EL element. Figure 5

[0025] Figure 7 (a) to (d) are partial cross-sectional views schematically showing the manufacturing process of an organic EL element. Figure 6

[0026] Figure 8 is a flowchart showing the manufacturing process of an organic EL element.

[0027] Figure 9 is a diagram schematically showing the layered structure of an organic EL element in the aspect of the present disclosure.

[0028] Figure 10 is a table showing the results of a comparative experiment for verifying the effects of an organic EL element in the aspect of the present disclosure.

[0029] Figure 11 is a pattern diagram showing the layered structure in a first modification example of the second functional layer of an organic EL element.

[0030] ​​​Figure 12 is a mode diagram showing a stacked structure in a second modification example of the second functional layer of the organic EL element.

[0031] Figure 13 is a mode diagram showing a stacked structure in a third modification example of the second functional layer of the organic EL element.

[0032] Figure 14 is a mode diagram showing a stacked structure in a further modification example of the organic EL element.

[0033] Figure 15 is a mode diagram for explaining a light resonator structure.

[0034] Figure 16 is a schematic cross-sectional view of an organic EL display panel employing the light resonator structure.

[0035] Figure 17 is a mode diagram showing a stacked structure in a further modification example of the organic EL element.

[0036] Figure 18 is a mode diagram showing a stacked structure in a further modification example of the organic EL element.

[0037] Figure 19 is a mode diagram showing a stacked structure in a further modification example of the organic EL element.

[0038] Figure 20 is a mode diagram showing a stacked structure in a further modification example of the organic EL element.

[0039] Figure 21 (a) is a diagram showing a formation process of a hole injection layer in another aspect of the present disclosure, and (b) is an enlarged view of a portion corresponding to Figure 3 (b) the portion corresponding thereto.

[0040] Figure 22 (a) is a perspective view showing the state of a partition wall in the linear bump method, and (b) is a perspective view showing the state of a partition wall in the pixel bump method.

[0041] Figure 23 is a schematic cross-sectional view showing the configuration of a bottom emission type organic EL display panel.

[0042] Figure 24 is a mode diagram showing a stacked structure of an organic EL display panel excellent in flexibility.

[0043] Figure 25 is a mode diagram showing a stacked structure of a series connection type organic EL display panel.

[0044] Figure 26FIG. 1 is a diagram showing an example of a television device as an electronic device in which the organic EL display device according to the present disclosure is mounted. DETAILED DESCRIPTION

[0045] Implementation procedure of one aspect of the present disclosure

[0046] At present, each functional layer of the organic EL display panel is formed by a dry process such as vacuum evaporation (dry method), but with the progress of coating technology, particularly printing technology, in recent years, the technology of forming each functional layer by a wet process has been increasingly popular.

[0047] The wet process refers to printing an ink in which an organic or inorganic functional material is dissolved or dispersed in a solvent on a desired site by a printing device, and then drying the ink to form a functional layer, because even a large display panel can be controlled in equipment cost, and is relatively preferred in terms of cost, such as material utilization rate, etc.

[0048] In the case where each functional layer, particularly the light emitting layer, is formed by a printing process, in order to prevent the ink of adjacent sub-pixels from mixing with each other, a partition wall is provided to separate them, and the partition wall is also formed by a wet process using a resin material, thus achieving the advantage in terms of cost.

[0049] As shown in Patent Document 1, in order to facilitate the movement of electrons to the light emitting layer, an electron transport layer doped with an alkali metal or the like having a low work function into an organic material is sometimes formed between the cathode and the light emitting layer, thereby maintaining a good carrier balance and further optimizing the light emitting efficiency of the light emitting layer.

[0050] However, the alkali metal or the like is highly active, and even if a small amount of moisture is contained in the resin material of the partition wall or the light emitting layer as described above, the moisture will eventually penetrate into the electron injection layer, and the alkali metal or the like in the electron transport layer will react with the moisture to deteriorate, thereby causing a significant deterioration in electron injection property. As a result, this can lead to a deterioration in light emitting efficiency and a reduction in service life.

[0051] In Patent Document 1, a buffer layer composed of Alq3, 4,4'-N,N'-dicarbazole-biphenyl (CBP), or the like is provided between the electron transport layer and the light emitting layer, but it does not contain any organic material, so it cannot fully function in inhibiting the penetration of moisture into the electron transport layer.

[0052] In addition, in recent years, in order to quickly and uniformly apply the ink of the light emitting layer, a method (line-shaped bump method) is sometimes used in which each column of pixels arranged in a line shape is separated by a bump, and the ink is applied in a strip shape. It is generally believed that in this case, the contact area with the functional layer as the base of the light emitting layer increases, and the moisture in the functional layer moves to the electron transport layer, gradually leading to a deterioration in the characteristics of the electron transport layer.

[0053] Not only an organic EL display panel using an organic EL element as a light emitting element, a quantum dot display panel and the like in which a light emitting layer is composed of a quantum dot light emitting element (QLED: quantum dot-LED), and a display panel provided with a self-light emitting element and formed with a functional layer by a wet process, the problems are also similarly generated.

[0054] Thus, the present inventors and others have conducted intensive research in order to find a configuration that can achieve good light emitting efficiency and does not shorten the service life even when a linear bump method is used while reducing costs using a wet process, and have thereby realized the present solution.

[0055] "Outline of one solution of the present disclosure"

[0056] In a self-light emitting element of one solution of the present disclosure, a light emitting layer is provided between an anode and a cathode, and the self-light emitting element is provided with: a first functional layer provided between the light emitting layer and the cathode, containing a fluoride of a metal selected from alkali metals, alkaline earth metals, or rare earth metals; and a second functional layer provided between the first functional layer and the cathode, containing a rare earth metal as a dopant material.

[0057] With this solution, at least one functional layer can be formed using a wet process, and the light emitting efficiency of the self-light emitting element can be improved while reducing manufacturing costs, and the service life can be extended.

[0058] In addition, as a self-light emitting element in another solution of the present disclosure, in the above solution, the film thickness of the first functional layer is 0.1 nm or more and 20 nm or less.

[0059] According to this solution, a self-light emitting element can be obtained that can exhibit moisture barrier properties by the metal fluoride in the first functional layer, while ensuring electron injection properties by the second functional layer containing a rare earth metal as a dopant material, and can achieve good light emitting efficiency and does not shorten the service life.

[0060] In addition, as a self-light emitting element in another solution of the present disclosure, in the above solution, the film thickness of the second functional layer is 5 nm or more and 150 nm or less.

[0061] According to this solution, the metal fluoride in the first functional layer can exhibit moisture barrier properties while reducing a portion of the metal fluoride, and the effect of electron injection by the rare earth metal contained in the second functional layer can be exhibited. In addition, a self-light emitting element can be obtained that can buffer sputtering damage even when ITO and IZO, for example, formed by a sputtering method, are formed on the second functional layer as a third functional layer, and can achieve good light emitting efficiency and does not shorten the service life.

[0062] Further, as the self-light-emitting element in another aspect of the present disclosure, in the above aspect, the second functional layer includes a first layer portion provided on the first functional layer, and a second layer portion provided on the first layer portion, and the content ratio of the rare earth metal in the second layer portion is greater than the content ratio of the rare earth metal in the first layer portion.

[0063] Further, as the self-light-emitting element in another aspect of the present disclosure, in the above aspect, the second functional layer is formed of a first layer portion, a second layer portion, and a third layer portion, which are stacked in this order from the side closer to the first functional layer, and if the content ratios of the rare earth metal in the first layer portion, the second layer portion, and the third layer portion are represented by X1, X2, and X3, respectively, X2 < X1 ≤ X3.

[0064] By changing the concentration of the rare earth metal in the film thickness direction of the second functional layer as above, it is possible to appropriately reduce the first functional layer while exerting the moisture barrier property of the metal fluoride of the first functional layer, to improve the electron injection property to the light-emitting layer, and to prevent excessive reduction in light transmittance due to an increase in the doping amount of the rare earth metal. Further, by increasing the concentration of the rare earth metal of the third layer portion, it is possible to improve the electron injection property from the cathode side to the second functional layer, and to prevent moisture from penetrating from the outside, thereby further prolonging the service life of the self-light-emitting element.

[0065] Further, as the self-light-emitting element in another aspect of the present disclosure, in the above aspect, the content of the rare earth metal in the second functional layer continuously increases from the first functional layer toward the cathode.

[0066] By continuously changing the content of the rare earth metal of the second functional layer as above, it is possible to appropriately reduce the first functional layer while exerting the moisture barrier property of the metal fluoride of the first functional layer, to more suppress the penetration of moisture into the second functional layer, and to prevent excessive reduction in light transmittance due to an increase in the doping amount of the rare earth metal, although the electron injection property is limited. Further, by increasing the concentration of the rare earth metal of the cathode side, it is possible to improve the electron injection property from the cathode side to the second functional layer, and to prevent moisture from penetrating from the outside, thereby further prolonging the service life of the self-light-emitting element.

[0067] Further, as the self-light-emitting element in another aspect of the present disclosure, in the above aspect, a transparent conductive film is formed as a third functional layer between the second functional layer and the cathode.

[0068] Further, as the self-light-emitting element in another aspect of the present disclosure, in the above aspect, the film thickness of the third functional layer is 15 nm or more.

[0069] According to this aspect, by adjusting the film thickness of the third functional layer, a light resonator structure corresponding to the wavelength of the emitted light color can be constructed.

[0070] Further, in the self-light-emitting element according to another aspect of the present disclosure, in the above aspect, a thin film including a rare earth metal having a film thickness of 0.1 nm or more and 3 nm or less is formed between the second functional layer and the third functional layer.

[0071] Further, in the self-light-emitting element according to another aspect of the present disclosure, in the above aspect, a thin film including a rare earth metal having a film thickness of 0.1 nm or more and 3 nm or less is formed between the third functional layer and the cathode.

[0072] Further, in the self-light-emitting element according to another aspect of the present disclosure, in the above aspect, a thin film including a rare earth metal having a film thickness of 0.1 nm or more and 5 nm or less is formed on the side of the cathode opposite to the light-emitting layer.

[0073] According to this aspect, in addition to being able to improve the film quality of the cathode, it is also possible to prevent moisture from entering from the outside, thereby further extending the service life of the self-light-emitting element.

[0074] Further, in the self-light-emitting element according to another aspect of the present disclosure, in the above aspect, the anode has light reflectivity, and the cathode has semi-transmissivity.

[0075] Here, in the self-light-emitting element according to another aspect of the present disclosure, in the above aspect, the light emitted in the light-emitting layer includes a first light beam directly emitted from the cathode, and a second light beam emitted from the cathode after being reflected between the anode and the cathode, respectively, and the film thickness of at least one functional layer between the light-emitting layer and the cathode is set according to the wavelength of the emitted light color so that the first light beam and the second light beam resonate.

[0076] According to this aspect, it is possible to construct a light resonator formed between the interface of the anode and the interface of the cathode, thereby further improving the light-emitting efficiency of the self-light-emitting element.

[0077] In the self-light-emitting element according to another aspect of the present disclosure, at least one functional layer between the anode and the cathode is a coating film.

[0078] In the self-light-emitting element according to another aspect of the present disclosure, the fluoride of the metal selected from the alkali metal, the alkaline earth metal, or the rare earth metal is NaF.

[0079] Further, in the self-light-emitting element according to another aspect of the present disclosure, the rare earth metal is Yb.

[0080] Further, in another aspect of the present disclosure, a self-light-emitting display panel in which a plurality of the self-light-emitting elements according to the above aspect are arranged in a matrix form, and the light-emitting layers of the self-light-emitting elements adjacent to each other in the row direction are separated by the partition walls extending in the column direction.

[0081] Thus, a self-light-emitting display panel having excellent light-emitting efficiency and capable of prolonging the service life can be provided.

[0082] Further, in another aspect of the present disclosure, the self-light-emitting display panel is of a top emission type.

[0083] In the self-light-emitting display panel of the top emission type, no driving circuit composed of a TFT or the like is provided in the light emission direction, and thus the aperture ratio of each self-light-emitting element can be increased, and thus the light-emitting efficiency is excellent.

[0084] Further, in another aspect of the present disclosure, a self-light-emitting display device includes the self-light-emitting display panel according to the above aspect and a driving unit that drives the self-light-emitting display panel to display an image.

[0085] Further, in another aspect of the present disclosure, an electronic device includes the self-light-emitting display device according to the above aspect as an image display unit.

[0086] The self-light-emitting display device and the display panel of the electronic device have excellent light-emitting efficiency and can prolong the service life.

[0087] Further, in another aspect of the present disclosure, a method for manufacturing a self-light-emitting element includes:

[0088] a first step of forming an anode;

[0089] a second step of forming a light-emitting layer over the anode;

[0090] a third step of forming a first functional layer containing a fluoride of a metal selected from an alkali metal, an alkaline earth metal, or a rare earth metal over the light-emitting layer;

[0091] a fourth step of forming a second functional layer in which a rare earth metal is used as a dopant material over the first functional layer; and

[0092] a fifth step of forming a cathode over the second functional layer.

[0093] According to the aspect, a self-light-emitting element having excellent light-emitting efficiency and capable of displaying a high-quality image can be manufactured.

[0094] Further, in another aspect of the present disclosure, the fourth step of the method for manufacturing a self-light-emitting element according to the above aspect includes doping a rare earth metal in an organic material layer after the formation of the organic material layer over the first functional layer to form the second functional layer.

[0095] Further, as a manufacturing method of a self-light-emitting display element in another aspect of the present disclosure, the fourth process simultaneously vapor-deposits an organic material and the rare earth metal on the first functional layer to form a second functional layer.

[0096] Further, between the first process and the second process, a process of forming a hole-transporting layer having a function of promoting movement of holes is further included, and the process of forming the hole-transporting layer and at least one of the second process, the third process, and the fourth process are performed by a wet process.

[0097] Thus, it is easy to reduce manufacturing costs.

[0098] Note that in each of the above-described aspects of the present disclosure, "upper" does not mean the upper side (vertically upward) in the absolute spatial recognition, but is defined based on the stacking order of the stacked structure of the self-light-emitting element, and is defined based on the relative positional relationship. Specifically, in the self-light-emitting element, the direction perpendicular to the main surface of the substrate, that is, the side from the substrate toward the side of the stack is regarded as the upper side. Further, in the case where, for example, it is stated as "on the substrate", it does not mean only the region directly connected to the substrate, but also includes the region above the substrate sandwiching the stack. Further, in the case where, for example, it is stated as "above the substrate", it does not mean only the region above the substrate with a gap, but also includes the region on the substrate.

[0099] <Embodiment>

[0100] Hereinafter, an organic EL element, an organic EL display panel, and an organic EL display device in one aspect of the present disclosure will be described with reference to the drawings. Note that the drawings are schematic, and the scale of each component and the ratio of length to width, etc. can be different from actual ones.

[0101] 1. Overall configuration of organic EL display device 1

[0102] Figure 1 is a block diagram showing the overall configuration of the organic EL display device 1. The organic EL display device 1 is a display device for a television, a personal computer, a mobile terminal, a commercial display (electronic sign, commercial facility large screen), or the like.

[0103] The organic EL display device 1 includes an organic EL display panel 10 and a drive control portion 200 electrically connected to the organic EL display panel 10.

[0104] In the present embodiment, the organic EL display panel 10 is a top emission type display panel, and the upper surface thereof is a rectangular image display surface. In the organic EL display panel 10, a plurality of organic EL elements (not shown) are arranged along the image display surface, and an image is displayed by combining the light emission of each organic EL element. Note that the organic EL display panel 10 exemplarily employs an active matrix system.

[0105] The drive control section 200 has a drive circuit 210 connected to the organic EL display panel 10, and a control circuit 220 connected to an external device such as a computer or a receiving device such as an antenna. The drive circuit 210 has a power supply circuit that supplies power to each organic EL element, a signal circuit that applies a voltage signal for controlling the power supply to each organic EL element, and a scanning circuit that switches the position at which the voltage signal is applied at regular intervals, and the like.

[0106] The control circuit 220 controls the operation of the drive circuit 210 based on data containing image information input from the external device and the receiving device.

[0107] Needless to say, Figure 1 In the present embodiment, four drive circuits 210 are arranged around the organic EL display panel 10, but the configuration of the drive control section 200 is not limited thereto, and the number and position of the drive circuits 210 can be appropriately changed. In the following description, as shown in FIG. 1, the direction along the long side of the upper surface of the organic EL display panel 10 is set as the X direction, and the direction along the short side of the upper surface of the organic EL display panel 10 is set as the Y direction. Figure 1

[0108] 2. Configuration of the organic EL display panel 10

[0109] (A) Plan view configuration

[0110] Figure 2 is a schematic plan view of a portion of the image display surface of the organic EL display panel 10. In the organic EL display panel 10, sub-pixels 100R, 100G, 100B that emit light in R (red), G (green), and B (blue), respectively (hereinafter also referred to as R, G, and B) are arranged in a matrix pattern. The sub-pixels 100R, 100G, 100B are alternately arranged in the X direction, and one group of sub-pixels 100R, 100G, 100B arranged in the X direction constitutes one pixel P. In the pixel P, the emission brightness of the sub-pixels 100R, 100G, 100B controlled by the gradation is combined, and full color can be expressed.

[0111] In addition, in the Y direction, only any one of the sub-pixel 100R, the sub-pixel 100G, and the sub-pixel 100B is arranged, and thus a sub-pixel column CR, a sub-pixel column CG, and a sub-pixel column CB are respectively formed. Thus, as the entire organic EL display panel 10, the pixels P are arranged in a matrix pattern in the X direction and the Y direction, and the color rendering of the pixels P arranged in the matrix pattern is combined, and an image is displayed on the image display surface.

[0112] ​Subpixels 100R, 100G, and 100B are respectively equipped with organic EL elements 2(R), 2(G), and 2(B) that emit light of colors R, G, and B (see...). Figure 3 ).

[0113] Furthermore, the organic EL display panel 10 in this embodiment adopts a so-called linear bump method. That is, multiple partitions (bumps) 14 are arranged at intervals along the X direction to separate the sub-pixel columns CR, CG, and CB one column at a time. In each sub-pixel column CR, CG, and CB, the sub-pixels 100R, 100G, and 100B share the same light-emitting layer.

[0114] However, in each sub-pixel column CR, CG, CB, multiple pixel confinement layers 141 are arranged at intervals along the Y direction to insulate sub-pixels 100R, 100G, 100B from each other, so that each sub-pixel 100R, 100G, 100B can emit light independently.

[0115] It should be noted that the height of the pixel confinement layer 141 is lower than the height of the ink surface when the light-emitting layer is applied. Figure 2 In the image, the partition 14 and the pixel confinement layer 141 are represented by dashed lines because the pixel confinement layer 141 and the partition 14 are not exposed to the surface of the image display surface, but are disposed inside the image display surface.

[0116] (B) Cross-sectional composition

[0117] Figure 3 (a) is along Figure 2 A schematic cross-sectional view of line AA.

[0118] In the organic EL display panel 10, a pixel is composed of three sub-pixels that emit R, G, and B light respectively, and each sub-pixel is composed of organic EL elements 2(R), 2(G), and 2(B) that emit light of the corresponding color.

[0119] Organic EL elements 2(R), 2(G), and 2(B) of each emitting color have essentially the same structure, therefore, without distinction, they will be described as organic EL element 2.

[0120] like Figure 3 As shown in (a), the organic EL element 2 includes a substrate 11, an interlayer insulating layer 12, a pixel electrode (anode) 13, a partition 14, a hole injection layer 15, a hole transport layer 16, a light-emitting layer 17, a first functional layer 18, a second functional layer 19, a counter electrode (cathode) 20, and a sealing layer 21.

[0121] The substrate 11, the interlayer insulating layer 12, the first functional layer 18, the second functional layer 19, the counter electrode 20, and the sealing layer 21 are not formed for each pixel, but are commonly formed for the plurality of organic EL elements 2 provided in the organic EL display panel 10.

[0122] (1) Substrate

[0123] The substrate 11 includes a base material 111 that is an insulating material, and a TFT (Thin Film Transistor) layer 112. On the TFT layer 112, a drive circuit is formed for each sub-pixel. The base material 111 can employ, for example, a glass substrate, a quartz substrate, a silicon substrate, a molybdenum sulfide, a metal substrate of copper, zinc, aluminum, stainless steel, magnesium, iron, nickel, gold, silver, and the like, a semiconductor substrate of gallium arsenide, and the like, or a plastic substrate.

[0124] The plastic material can use any one of a thermoplastic resin, a thermosetting resin. As examples, various thermoplastic elastomers such as polyethylene, polypropylene, polyamide, polyimide (PI), polycarbonate, acrylic resin, polyethylene terephthalate (PET), polybutylene terephthalate, polyacetal, other fluorine-based resin, styrene-based, polyolefin-based, polyvinyl chloride-based, polyurethane-based, fluororubber-based, chlorinated polyethylene-based, epoxy resin, unsaturated polyester, silicone resin, polyurethane, or the like, or a copolymer, a blend, a polymer alloy, or the like in which these are the main component, or a laminate in which one or two or more of these are laminated, can be used.

[0125] (2) Interlayer insulating layer

[0126] The interlayer insulating layer 12 is formed on the substrate 11. The interlayer insulating layer 12 is composed of a resin material, and is used to planarize the step of the upper surface of the TFT layer 112. As the resin material, a positive photosensitive material can be cited, for example. In addition, as such a photosensitive material, an acrylic resin, a polyimide resin, a siloxane resin, a phenol resin can be cited. In addition, on the interlayer insulating layer 12, a contact hole is formed for each sub-pixel, but Figure 3 is not shown in the cross-sectional view.

[0127] (3) Pixel electrode

[0128] The pixel electrode 13 includes a metal layer composed of a light-reflective metal material, and is formed on the interlayer insulating layer 12. The pixel electrode 13 is provided for each sub-pixel, and is electrically connected to the TFT layer 112 through a contact hole (not shown).

[0129] In the present embodiment, the pixel electrode 13 functions as an anode.

[0130] As specific examples of the metal material having light reflectivity, Ag (silver), Al (aluminum), an aluminum alloy, Mo (molybdenum), APC (an alloy of silver, palladium, and copper), ARA (an alloy of silver, rubidium, and gold), MoCr (an alloy of molybdenum and chromium), MoW (an alloy of molybdenum and tungsten), NiCr (an alloy of nickel and chromium), and the like can be given.

[0131] The pixel electrode 13 can be formed of a single metal layer, or can be formed in a stacked structure by stacking a layer formed of a metal oxide such as ITO (indium tin oxide) or IZO (indium zinc oxide) on a metal layer.

[0132] (4) Barrier and pixel confinement layer

[0133] The barrier 14 is used to separate the plurality of pixel electrodes 13 arranged for each sub-pixel in the X direction (horizontal direction) above the substrate 11 column by column in the Y direction (vertical direction) between the sub-pixel columns CR, CG, and CB arranged in the X direction. Figure 2 The barrier 14 is in the shape of a linear protrusion extending in the Y direction between the sub-pixel columns CR, CG, and CB arranged in the X direction.

[0134] The barrier 14 is formed using an electrically insulating material. As a specific example of the electrically insulating material, an insulating organic material such as an acrylic resin, a polyimide resin, a novolak resin, a phenol resin, or the like is used.

[0135] The barrier 14 functions as a structure for preventing the various colors of ink applied when forming the light emitting layer 17 by an application method from mixing and overflowing.

[0136] Note that when a resin material is used, it is preferable for the resin material to have photosensitivity from the viewpoint of processability. The photosensitivity can be either of positive type or negative type.

[0137] The barrier 14 is preferably resistant to organic solvents and heat. In addition, in order to suppress the outflow of ink, the surface of the barrier 14 preferably has a predetermined lyophobicity.

[0138] The bottom surface of the barrier 14 is in contact with the upper surface of the interlayer insulating layer 12 in the portion where the pixel electrode 13 is not formed.

[0139] The pixel confinement layer 141 is formed of an electrically insulating material, and covers the end portions of the pixel electrodes 13 adjacent in the Y direction (vertical direction) in each sub-pixel column, in order to separate the pixel electrodes 13 adjacent in the Y direction from each other. Figure 2

[0140] The height of the pixel confinement layer 141 is slightly greater than the film thickness of the pixel electrode 13, but is lower than the position of the liquid surface when the ink of the light emitting layer is dropped into the opening portion 14a. In addition, it is also greater than the height of the light emitting layer 17 after drying, in order to ensure the insulation of the light emitting layers 17 from each other.

[0141] ​Thus, the pixel restricting layer 141 does not hinder the flow of ink when forming the light emitting layer 17. Therefore, it is easy to make the thickness of the light emitting layer 17 of each sub-pixel column uniform.

[0142] With the above structure, the pixel restricting layer 141 improves the electrical insulation of the pixel electrodes 13 adjacent in the Y direction, and also has the effects of suppressing the mid-way cutting of the light emitting layer 17 on each sub-pixel column CR, CG, CB, and improving the electrical insulation between the pixel electrode 13 and the counter electrode 20.

[0143] As a specific example of the electrical insulating material for the pixel restricting layer 141, resin materials and inorganic materials exemplified as the material of the barrier 14 described above can be cited. In addition, when forming the light emitting layer 17 as an upper layer, in order to make the ink easily wet and spread, the surface of the pixel restricting layer 141 preferably has a lyophilic property to the ink.

[0144] (5) Hole injection layer

[0145] In order to promote the injection of holes from the pixel electrode 13 to the light emitting layer 17, a hole injection layer 15 is provided on the pixel electrode 13. The hole injection layer 15 is a layer composed of, for example, an oxide of Ag (silver), Mo (molybdenum), Cr (chromium), V (vanadium), W (tungsten), Ni (nickel), Ir (iridium), or the like, or a conductive polymer material such as PEDOT (a mixture of polythiophene and polystyrene sulfonic acid). It can be formed by, for example, a sputtering process and a wet process.

[0146] In the above, the hole injection layer 15 composed of an oxide of a metal has a large work function, and stably injects holes to the light emitting layer 17.

[0147] (6) Hole transport layer

[0148] The hole transport layer 16 has a function of transporting holes injected from the hole injection layer 15 to the light emitting layer 17. The hole transport layer 16 is formed by a wet process using, for example, a high molecular compound such as polyfluorene and its derivative, or polyarylamine and its derivative, which does not have a hydrophilic group.

[0149] (7) Light emitting layer

[0150] The light emitting layer 17 is formed in the opening portion 14a, and has a function of emitting light of various colors of R, G, B by the recombination of holes and electrons. It should be noted that, in particular, when it is necessary to specify the color of light emission and describe it, it is written as the light emitting layer 17(R), 17(G), 17(B).

[0151] As the material of the light-emitting layer 17, specifically, it is preferable to be formed of a fluorescent substance such as an oxynoid compound, a perylene compound, a coumarin compound, a heterocoumarin compound, an oxazole compound, an oxadiazole compound, a pyrenone compound, a pyrrolopyrrole compound, a naphthalene compound, an anthracene compound, a fluorene compound, a fluoranthene compound, a tetracene compound, a pyrene compound, a chrysene compound, a quinolone compound, and an azacarbazole compound, a pyrazoline derivative and a pyrazolone derivative, a rhodamine compound, a phenanthrene compound, a cyclopentadiene compound, a stilbene compound, a benzoquinone compound, a styryl compound, a butadiene compound, a dicyanomethylene pyran compound, a dicyanomethylene thiopyran compound, a fluorescein compound, a pyrylium compound, a thiopyrylium compound, a selenapyrylium compound, a telluropyrylium compound, an aromatic conjugated Alder diene compound, an oligo-phenylene compound, a thianthrene compound, a cyanine compound, an acridine compound, a metal complex of an 8-hydroxyquinoline compound, a metal complex of a 2- bipyridine compound, a complex of a Schiff base and a Group III metal, a quinoline metal complex, a rare earth complex, and the like.

[0152] The light-emitting layer 17 is formed by a wet process.

[0153] (8) First functional layer

[0154] The first functional layer 18 has a function of inhibiting the movement of moisture from the lower organic layer to the second functional layer 19 and transporting electrons from the opposing electrode 20 to the light-emitting layer 17. The first functional layer 18 contains a fluoride of a metal selected from alkali metals, alkaline earth metals, or rare earth metals (hereinafter referred to as "alkali metal or the like fluoride").

[0155] In general, the alkali metal or the like fluoride has the following advantages: the crystal structure is dense, the moisture permeability is low, the moisture barrier property is excellent, and by evaporating a material having a reducing property on the upper layer, a part of the alkali metal or the like is freed, thereby making the electron injection property excellent. Among them, NaF (sodium fluoride) is particularly excellent in moisture barrier property and electron injection property, and in the present embodiment, the first functional layer 18 is also configured to contain NaF.

[0156] Note that, as metal fluorides other than the above sodium fluoride, ytterbium fluoride (YbF3), lithium fluoride (LiF), barium fluoride (BaF2) are suitable. In addition, as alkali metal fluorides, cerium fluoride (CeF3), lithium fluoride (LiF), sodium fluoride (NaF) can be used; as alkaline earth metal fluorides, calcium fluoride (CaF2), magnesium fluoride (MgF2), barium fluoride (BaF2) can be used; as rare earth metal fluorides, lanthanum fluoride (LaF3), neodymium fluoride (NdF3), samarium fluoride (SmF3), ytterbium fluoride (YbF3), yttrium fluoride (YF3), gadolinium fluoride (GdF3), and the like can be used.

[0157] In order to sufficiently exert the effect of the first functional layer 18 of preventing moisture contained in the light-emitting layer 17 and the hole-transport layer 16 from being absorbed into the second functional layer 19 and the effect of improving the electron injection property from the second functional layer 19 to the light-emitting layer 17, it is preferable that the first functional layer 18 be directly stacked on the light-emitting layer 17.

[0158] (9) Second functional layer 19

[0159] The second functional layer 19 has a function of injecting and transporting electrons provided from the counter electrode 20 to the light-emitting layer 17 side. The second functional layer 19 is formed using an organic material, particularly an organic material having an electron-transport property, as a host material, and a rare earth metal as a dopant material. The rare earth metal generally has a low work function, an excellent electron injection property, and a reducing property, and thus has an effect of dissociating a fluoride such as an alkali metal in the first functional layer 18. In addition, the chemical stability is higher than that of an alkaline earth metal such as Ba, and thus is less likely to react with moisture (high moisture resistance), and is expected to extend the service life.

[0160] Among the rare earth metals, Yb (ytterbium) has a low melting point and high processability, and thus Yb is used as a dopant material in this embodiment.

[0161] Note that, as the rare earth metal other than Yb, La (lanthanum), Nd (neodymium), Sm (samarium), Eu (europium), Gd (gadolinium), Ce (cerium), Lu (lutetium), and the like can be used.

[0162] In addition, as the organic material having an electron-transport property (host material), π-electron-based low-molecular organic materials such as an oxadiazole derivative (OXD), a triazole derivative (TAZ), a phenanthroline derivative (BCP, Bphen), and the like can be given, but are not limited thereto.

[0163] (10) Counter electrode

[0164] In this embodiment, the organic EL display panel 10 is a top-emitting type; therefore, the counter electrode 20 is made of a light-transmitting conductive material and is formed on the second functional layer 19. The counter electrode 20 serves as a cathode.

[0165] As the counter electrode 20, a metal thin film or a transparent conductive film such as ITO or IZO can be used. To more effectively obtain the optical resonator structure, a metal thin film is preferably formed, which is composed of at least one material selected from aluminum, magnesium, silver, aluminum-lithium alloys, magnesium-silver alloys, etc., which serve as the material of the counter electrode 20. In this case, the effective thickness of the metal thin film is 5 nm or more and 30 nm or less.

[0166] When the optical resonator structure described above is adopted, it is preferable to form a transparent conductive film such as ITO and IZO with the required film thickness between the second functional layer 19 and the opposite electrode 20, and adjust the optical distance between the light-emitting layer 17 and the opposite electrode 20 to an appropriate size (see the modified example (2) described later).

[0167] (11) Sealing layer

[0168] The sealing layer 21 is designed to prevent the organic layers such as the hole transport layer 16, the light-emitting layer 17, and the second functional layer 19 from being exposed to moisture or air and thus deteriorating.

[0169] The sealing layer 21 is formed using a light-transmitting material such as silicon nitride (SiN) or silicon oxynitride (SiON).

[0170] (12) Other

[0171] A polarizing film or upper substrate for anti-glare purposes can be adhered to the sealing layer 21 using a transparent adhesive, but Figure 3 (a) is not shown. Additionally, color filters for correcting the chromaticity of the light emitted by each organic EL element 2 can be attached. This further protects the hole transport layer 16, the light-emitting layer 17, the second functional layer 19 from external moisture and air.

[0172] Figure 3 (b) is from Figure 3 (a) is an enlarged view of the portion enclosed by the dashed circle C. As described above, since the hole transport layer 16 and the light-emitting layer 17 are formed by a wet process, the pinning portions (the contact positions with the partition wall 14) P1 and P2 are higher than the central flat portion. Therefore, by observing the surface shape of each layer, it is easy to determine whether the layer is a coating film formed by a wet process.

[0173] 3. Manufacturing method of organic EL display panel 10

[0174] The manufacturing method of the organic EL display panel 10 will now be described using the accompanying drawings.

[0175] Figure 4 (a)~(e) Figure 5 (a)~(d) Figure 6 (a), (b) and Figure 7 (a) to (d) are schematic cross-sectional views showing the state of the organic EL display panel 10 at each stage of its manufacturing process. Additionally, Figure 8 This is a flowchart illustrating the manufacturing process of the organic EL display panel 10.

[0176] (1) Substrate preparation process

[0177] First, such as Figure 4 As shown in (a), a TFT layer 112 is formed on a substrate 111 to prepare the substrate 11. Figure 8 Step S1). The TFT layer 112 can be formed using known TFT manufacturing methods.

[0178] (2) Interlayer insulation layer formation process

[0179] Next, as Figure 4 As shown in (b), an interlayer insulating layer 12 is formed on the substrate 11. Figure 8 Step S2).

[0180] Specifically, a resin material with a certain degree of fluidity is applied along the upper surface of the substrate 11 by, for example, a molding process, to fill the unevenness on the substrate 11 caused by the TFT layer 112. As a result, the upper surface of the interlayer insulating layer 12 forms a shape that is planarized along the upper surface of the substrate 111.

[0181] Additionally, a dry etching method is applied to a portion of the interlayer insulating layer 12 located on, for example, the source electrode of the TFT element, to form a contact hole (not shown). The contact hole is formed using patterning or the like so that the surface of the source electrode is exposed at the bottom.

[0182] Next, a connection electrode layer is formed along the inner wall of the contact hole. A portion of the upper part of the connection electrode layer is disposed on the interlayer insulating layer 12. The connection electrode layer can be patterned using, for example, sputtering, after the metal film is formed, photolithography and wet etching.

[0183] (3) Formation process of pixel electrode and hole injection layer

[0184] Next, as Figure 4 As shown in (c), a pixel electrode material layer 130 is formed on the interlayer insulating layer 12. The pixel electrode material layer 130 can be formed by, for example, vacuum evaporation or sputtering.

[0185] Then, a hole injection material layer 150 is formed on the pixel electrode material layer 130. Figure 4 (d) The hole-injected material layer 150 can be formed using, for example, reactive sputtering.

[0186] Next, as Figure 4 As shown in (e), the pixel electrode material layer 130 and the hole injection material layer 150 are patterned by etching to form a plurality of pixel electrodes 13 and hole injection layers 15 for each sub-pixel. Figure 8 Step S3).

[0187] It should be noted that the method of forming the pixel electrode 13 and the hole injection layer 15 is not limited to the above method. For example, the hole injection layer 15 can be formed after the pixel electrode material layer 130 is patterned to form the pixel electrode 13.

[0188] (4) Partition and pixel confinement layer formation process

[0189] Next, the partition 14 and the pixel confinement layer 141 are formed. Figure 8 Step S4).

[0190] In this embodiment, the pixel confinement layer 141 and the partition 14 are formed through different processes.

[0191] (4-1) Pixel confinement layer formation

[0192] First, in order to make the Y direction ( Figure 2 The pixel electrode array on the surface is separated by each sub-pixel to form a pixel confinement layer 141 extending along the X direction.

[0193] like Figure 5 As shown in (a), a photosensitive resin material, which serves as the material for the pixel confinement layer 141, is uniformly coated on the interlayer insulating layer 12 on which the pixel electrode 13 and the hole injection layer 15 are formed, thereby forming a pixel confinement layer material layer 1410 having a film thickness equal to the height of the pixel confinement layer 141 to be formed.

[0194] As a specific coating method, wet processes such as die coating, slot coating, and spin coating can be used. After coating, it is preferable to perform processes such as vacuum drying and low-temperature heating drying (pre-baking) at around 60°C to 120°C to remove excess solvent and fix the pixel confinement layer material layer 1410 to the interlayer insulating layer 12.

[0195] Next, the pixel confinement layer material layer 1410 is patterned using photolithography.

[0196] For example, when the pixel confinement layer material layer 1410 has positive photosensitive properties, the portion that is retained as the pixel confinement layer 141 is shielded from light, while the portion to be removed is exposed to the pixel confinement layer material layer 1410 through a transparent photomask (not shown).

[0197] Next, development is performed to remove the exposed areas of the pixel confinement layer material layer 1410, thereby forming the pixel confinement layer 141. As a specific development method, for example, the substrate 11 can be immersed in a developer such as an organic solvent or an alkaline solution, and then the substrate 11 can be cleaned with a rinsing solution such as pure water. In this case, the developer dissolves the photosensitive portion of the pixel confinement layer material layer 1410 that has been exposed to light.

[0198] Then, by firing (post-baking) at a predetermined temperature, a pixel confinement layer 141 extending in the X direction can be formed on the interlayer insulating layer 12. Figure 5 (b)).

[0199] (4-2) Septation formation

[0200] Next, a partition 14 extending in the Y direction is formed in the same manner as the pixel confinement layer 141 described above.

[0201] That is, on the interlayer insulating layer 12 on which the pixel electrode 13, hole injection layer 15, and pixel confinement layer 141 are formed, a resin material for the partition is applied using a molding process or the like, thereby forming a partition material layer 140 having a film thickness equal to the height of the partition 14 to be formed. Figure 5 (c) After patterning the partition 14 extending along the Y direction on the partition material layer 140 by photolithography, it is fired at a predetermined temperature to form the partition 14. Figure 5 (d)).

[0202] It should be noted that although the above-mentioned patterning is performed after forming the material layers of pixel confinement layer 141 and partition 14 separately by wet process, it is also possible to form any one or both of the material layers by dry process and then perform patterning by photolithography and etching.

[0203] (5) Hole transport layer formation process

[0204] Next, as Figure 6 As shown in (a), ink comprising the constituent material of the hole transport layer 16 is ejected from the nozzle 3011 of the coating head 301 of the printing apparatus into the opening 14a restricted by the partition wall 14, so as to coat it onto the hole injection layer 15 within the opening 14a. At this time, ink is spray ... Figure 2 The ink for the hole transport layer 16 is applied in an extended manner. Then, it is allowed to dry to form the hole transport layer 16. Figure 8 Step S5).

[0205] (6) Light-emitting layer forming step

[0206] Next, a light-emitting layer 17 is formed over the hole-transport layer 16 (step S6 of FIG. 6). Figure 8

[0207] Specifically, as shown in (b), the ink containing the light-emitting material of the light-emitting color corresponding to each opening portion 14a is sequentially jetted from the nozzles 3011 of the coating heads 301 of the printing device and applied to the hole-transport layer 16 within the opening portion 14a. At this time, the ink is also continuously applied over the pixel confinement layer 141. By this, the ink can flow in the Y direction, reducing unevenness in the application of the ink, and further, the film thickness of the light-emitting layer 17 on the same sub-pixel column can be made uniform. Figure 6

[0208] Next, the substrate 11 after the application of the ink is sent into a vacuum drying chamber and heated under a vacuum atmosphere, thereby evaporating the organic solvent in the ink. By this, the light-emitting layer 17 can be formed.

[0209] (7) First functional layer forming step

[0210] Next, as shown in (a), a first functional layer 18 is formed over the light-emitting layer 17 and the partition wall 14 (step S7 of FIG. 6). The first functional layer 18 is formed by commonly forming a film of NaF on each sub-pixel using an evaporation method. Figure 7 Figure 8

[0211] (8) Second functional layer forming step

[0212] Next, as shown in (b), a second functional layer 19 is formed over the first functional layer 18 (step S8 of FIG. 6). The second functional layer 19 is formed by commonly forming a film of an organic material having electron-transport properties and a doped metal Yb on each sub-pixel, for example, using a simultaneous evaporation method. Figure 7 Figure 8

[0213] In addition, it is also possible to first form a film of an organic material having electron-transport properties and then dope Yb by a sputtering method or the like.

[0214] (9) Counter electrode forming step

[0215] Next, as shown in (c), a counter electrode 20 is formed over the second functional layer 19 (step S9 of FIG. 6). In the present embodiment, the counter electrode 20 is formed by forming a film of silver, aluminum or the like using a sputtering method, a vacuum evaporation method. Figure 7 Figure 8 (10) Sealing layer forming step

[0216] ​​​​​​​​

[0217] Next, as shown in (d), a sealing layer 21 is formed on the counter electrode 20 (step S10). The sealing layer 21 can be formed by film formation of SiON, SiN, etc. using a sputtering method, a CVD method, etc. Figure 7 (d) Next, as shown in (d), a sealing layer 21 is formed on the counter electrode 20 (step S10). The sealing layer 21 can be formed by film formation of SiON, SiN, etc. using a sputtering method, a CVD method, etc. Figure 8 (d) Next, as shown in (d), a sealing layer 21 is formed on the counter electrode 20 (step S10). The sealing layer 21 can be formed by film formation of SiON, SiN, etc. using a sputtering method, a CVD method, etc.

[0218] Thus, the organic EL display panel 10 is completed.

[0219] Needless to say, the above manufacturing method is merely an example and can be appropriately changed.

[0220] 4. Evaluation Experiment of Organic EL Element

[0221] Next, an evaluation experiment was performed on the emission efficiency and the service life of the organic EL element 2 formed by the above embodiment.

[0222] Figure 9 is a diagram schematically showing the layer stack structure of the main part (from the pixel electrode (anode) 13 to the counter electrode (cathode) 20) of the above organic EL element 2.

[0223] As the organic EL element 2 (embodiment) to be experimented, an Al alloy was vapor-deposited on a glass substrate to make a pixel electrode (anode) 13, and a hole injection layer 15, a hole transport layer 16, a light-emitting layer 17, a first functional layer 18, a second functional layer 19, and a counter electrode (cathode) 20 were sequentially stacked.

[0224] The first functional layer 18 was a NaF thin film having a film thickness of 2 nm and was formed by a vacuum vapor deposition method. The second functional layer 19 was formed by forming an organic material and Yb having a film thickness of 15 nm using a simultaneous vapor deposition method. The doping concentration of the doping metal Yb was 20 wt%.

[0225] The organic EL element in Comparative Example 1 did not form the first functional layer 18 in (d). Figure 9 The doping metal of the second functional layer 19 was Ba. This Ba is an alkaline earth metal and has a sufficiently low work function and is widely used as an n-type dopant at present.

[0226] The organic EL element in Comparative Example 2 did not form the first functional layer 18 in (d). Figure 9 The doping metal of the second functional layer 19 was Yb.

[0227] The organic EL element in Comparative Example 3 formed the first functional layer 18 of NaF and the doping metal of the second functional layer 19 was Ba.

[0228] The film thickness of the second functional layer and the doping concentration of the doping metal of Comparative Examples 1 to 3 were the same as those of the embodiment and were set to 15 nm and 20 wt%, respectively.

[0229] Further, the film thickness of the first functional layer 18 of Comparative Example 3 was 2 nm, which was the same as the working example.

[0230] The formation conditions of the other layers were the same as those of the working example and Comparative Examples 1 to 3.

[0231] Figure 10 Table 1 is a comparison table showing the results of evaluation of the luminous efficiency, driving voltage, service life, and overall evaluation of the working example and Comparative Examples 1 to 3.

[0232] In the column of luminous efficiency of the table, the luminous efficiency at the initial stage of light emission (total luminous flux per unit power, lm / W (lumen per watt)) is shown as a comparative value when the luminous efficiency of the working example is set to 100.

[0233] Further, in the column of driving voltage, the reciprocal of the driving voltage when a constant current is applied is shown as a comparative value when the working example is set to 100. Since the comparison is made by the reciprocal, the higher the value in this column, the lower the driving voltage.

[0234] In the column of service life, the results of the acceleration test are shown, and, for example, when the luminous efficiency reaches 80% or less of the initial value, it is judged that the service life is reached. In this case, the comparative value when the service life of the working example is set to 100 is also shown.

[0235] It should be noted that, as the overall evaluation, when the evaluation of the luminous efficiency, driving voltage, and service life described above is 95 points or more, the evaluation is "O", when it is 80 points or more and less than 95 points, the evaluation is "Δ", and when it is less than 80 points, the evaluation is "X".

[0236] Figure 10 Table 1 also shows that, in Comparative Examples 1 and 2 which do not have the first functional layer, the luminous efficiency decreases to about 60% of the working example. Further, the voltage is large, and the voltage is increased. Also, in the evaluation of the service life, Comparative Example 1 in which the doping metal of the second functional layer is Ba decreases to about 30%, and Comparative Example 2 in which the doping metal is Yb decreases to about 50%.

[0237] Further, in Comparative Example 3, the doping metal of the second functional layer is Ba, but it has the first functional layer composed of NaF, and thus the electron transport property is supplemented, and the evaluation values of the luminous efficiency and driving voltage are increased, and are only slightly inferior to the working example. However, the service life differs by 30 points from the working example.

[0238] Further, the only example in which the overall evaluation is "O" is the working example.

[0239] From the results of the experiments, the following can be known.

[0240] (a) Although the work function of Ba is smaller than that of Yb (the work function of Ba is 2.52 eV and the work function of Yb is 2.6 eV), the evaluation is slightly higher when the doping metal is Yb than when the doping metal is Ba in terms of luminous efficiency and driving voltage. It is generally considered that this is because the activity of the rare earth Yb is lower than that of the alkaline earth metal Ba, and it is not easily deteriorated by reaction with moisture in the production process of the light emitting device, and the voltage is also lower, and the amount of current is also reduced, thereby suppressing the reduction in efficiency.

[0241] (b) Since the activity of the rare earth metal Yb is lower than that of the alkaline earth metal Ba, and it is not easily deteriorated by reaction with moisture, the doping metal Yb is more advantageous from the viewpoint of service life.

[0242] (c) Although the difference in service life is 18% when the doping metal of the second functional layer is Ba and Yb in the case where the first functional layer is not present (Comparative Example 1, Comparative Example 2), the difference in service life reaches 30% when the doping metal of the second functional layer is Ba and Yb in the case where the first functional layer having NaF is present (Comparative Example 3, Working Example). It is presumed that this is because the combination of NaF and Yb has excellent phase properties, and by their synergistic effect, an organic EL element having more excellent resistance to moisture and a long service life is formed.

[0243] 5. Film thickness of the first functional layer and the second functional layer and doping concentration in the second functional layer

[0244] (1) Film thickness of the first functional layer

[0245] As described above, the NaF forming the first functional layer 18 has electron injecting properties and moisture blocking properties with respect to the light emitting layer 17, and the film thickness is preferably 0.1 nm or more and 20 nm or less. If the film thickness is less than 0.1 nm, the film thickness is too thin, and the effects of the electron injecting properties from the second functional layer 19 to the light emitting layer 17 and the moisture blocking properties with respect to the second functional layer 19 cannot be sufficiently exerted, and in addition, if the film thickness exceeds 20 nm, the reducing action of the second functional layer cannot sufficiently act on the first functional layer, and thus the electron injecting properties deteriorate.

[0246] (2) Film thickness of the second functional layer

[0247] The second functional layer 19 has excellent electron injecting properties of injecting electrons from the counter electrode 20 as a cathode, and has higher transparency than the existing Ba or the like, and thus the film thickness can be set to a range of 5 nm or more and 150 nm or less. This is because, if the film thickness is less than 5 nm, the film thickness is too thin, and the NaF as the first functional layer cannot be sufficiently reduced, and further, electrons cannot be sufficiently injected from the cathode, and in addition, if the film thickness exceeds 150 nm, it is difficult to perform optical adjustment, and the light extraction efficiency deteriorates, and it can have an influence on the luminous efficiency.

[0248] Since the film thickness of the second functional layer 19 can be taken in the above larger range, by optical design, the thickness of the second functional layer 19 can be set for the light emission colors of R, G, and B respectively within the range of the film thickness, thereby constructing a light resonance structure.

[0249] It should be noted that the first functional layer 18 assumes two functions, i.e., to prevent the movement of moisture from the lower organic layer to the second functional layer 19 and to inject electrons to the light emitting layer 17, and therefore, it is effective to directly stack the first functional layer 18 on the light emitting layer 17 and to directly form the second functional layer 19 on the first functional layer 18, whereby no additional intermediate layer is required, thereby reducing the process burden.

[0250] (3) Doping concentration of Yb in the second functional layer

[0251] Yb has a low work function, excellent electron injection property, and much lower reactivity to moisture than alkali metals and the like, and therefore, the doping concentration can be in the range of 1 wt% or more and 90 wt% or less. This is because, if it is less than 1 wt%, the desired electron injection property cannot be obtained, and if it exceeds 90 wt%, Yb blocks are easily generated at the time of evaporation and the like, and it is difficult to uniformly disperse in the organic layer as a host material.

[0252] 6. Effects (Summary)

[0253] As described above, according to the organic EL element in the scheme of the present disclosure, the first functional layer 18 composed of NaF is formed on the light emitting layer 17, and the second functional layer 19 doped with Yb is formed thereon.

[0254] The moisture barrier ability of NaF of the first functional layer 18 is high, and the electron injection property can be increased by the reducing action of Yb, and therefore, it is possible to suppress the moisture from the lower organic layers of the light emitting layer 17 and the barrier ribs 14 and the pixel confinement layer 141 from being immersed in the second functional layer 19 while functioning as an electron transport layer.

[0255] It should be noted that the fluoride of a metal selected from alkali metals, alkaline earth metals, or rare earth metals other than NaF also has similar properties, and therefore, it can also be used.

[0256] On the other hand, the doping metal Yb of the second functional layer 19 is a rare earth metal, and has a low work function, and therefore, the electron injection property is good, the light emission efficiency is improved, and the driving voltage can also be made low. Also, the above first functional layer 18, in addition to suppressing the moisture from the lower organic layers from being immersed, has a low reactivity to moisture compared to Yb itself and alkali metals and the like, and therefore, it is not easily deteriorated.

[0257] Note that the same effect can be obtained even if a metal other than Yb is doped as the rare earth metal. This is because the work function of the rare earth metal is low, it has reducing properties, and it has chemical stability as a common characteristic.

[0258] Therefore, at least one of the organic layers of the organic EL element 2 can be formed by a wet process to reduce manufacturing costs, while suppressing deterioration of the electron-injection properties of the second functional layer 19 caused by moisture contained in the organic layer, thereby extending the service life of the organic EL element.

[0259]

[0260] In the above, as one aspect of the present application, embodiments of the organic EL element, the organic EL display panel, the method of manufacturing the organic EL element, and the like were described, but the present application is not limited at all by the above description except for the essential characteristic components. Hereinafter, other aspects of the present application will be described.

[0261] (1) Modification of the configuration of the second functional layer

[0262] In the above embodiments, the second functional layer 19 is a single layer, and the doping concentration of Yb is uniform, but can be configured as follows.

[0263] (1-1) The second functional layer directly adopts a single layer structure, and the concentration gradient of Yb is provided in the film thickness direction

[0264] Figure 11 is a mode diagram showing the layered structure of the organic EL element 2 in the first modification.

[0265] Note that in this diagram, only the layered structure of the main part (from the pixel electrode 13 to the counter electrode 20) of the organic EL element 2 in the present modification is shown (in addition to the Figure 19 、 Figure 20 、 Figure 24 、 Figure 25 , the layered structure diagrams of other modifications are the same.).

[0266] As shown in Figure 11 , the doping concentration of Yb of the second functional layer 19 is X2wt% at the side in contact with the counter electrode 20, and the doping concentration decreases as it approaches the first functional layer 18, and the concentration reaches X1wt% (1≤X1X2≤90) at the portion in contact with the first functional layer 18.

[0267] ​By making such a configuration, the Yb content of the second functional layer is continuously varied, thereby enabling the first functional layer to exhibit a weaker reducing property while exhibiting the moisture barrier property of NaF of the first functional layer, to inhibit the invasion of moisture into the second functional layer, and to prevent excessive reduction in light transmittance due to an increase in the Yb doping amount, although the electron injection property is limited. In addition, by increasing the concentration on the cathode side, the electron injection property from the cathode side into the second functional layer can be improved, and the moisture can be inhibited from being infiltrated from the outside, further prolonging the service life of the organic EL element.

[0268] Thus, an organic EL element having excellent luminous efficiency and a long service life can be provided.

[0269] Note that, as a method of gradually varying the doping concentration of Yb, for example, in a simultaneous evaporation method, the temperature of an electric furnace for heating Yb and the temperature of an electric furnace for heating an organic material are separately controlled to gradually slow down the evaporation speed of Yb with respect to the evaporation speed of the organic material, thereby achieving a concentration gradient.

[0270] (1-2) Second functional layer has a two-layer structure

[0271] Figure 12 is a mode diagram showing the layered structure of the organic EL element 2 in a second modification example.

[0272] As shown in Figure 12 , the second functional layer 19 has a two-layer structure of a first layer portion 191 and a second layer portion 192, and the doping concentration of Yb (X2wt%) of the second layer portion 192 is higher than the doping concentration of Yb (X1wt%) of the first layer portion 191 (1≤X1X2≤90).

[0273] Note that, by some manufacturing method, there can be a portion in which the doping concentration gradually transitions from X1wt% to X2wt% between the first layer portion 191 and the second layer portion 192, and this portion is small in terms of the entire film thickness of the second functional layer 19, and thus, even in such a case, the two-layer structure of the modification example can be considered. The three-layer structure described below also belongs to the same case.

[0274] In this way, in the second functional layer 19, the doping concentration of Yb is higher in the region on the side of the opposing electrode 20, that is, the second layer portion 192, than in the region on the side of the first functional layer 18, that is, the first layer portion 191, and thus, as in the modification example of (1-1) above, it is expected to improve the luminous efficiency and prolong the service life.

[0275] (1-3) Second functional layer has a three-layer structure

[0276] Figure 13is a pattern diagram showing a stacked structure of the organic EL element 2 in a second modification example.

[0277] As shown in Figure 13 , the second functional layer 19 is made into a three-layer structure of a first layer portion 191, a second layer portion 192, and a third layer portion 193, and when the doping concentrations of Yb in the first to third layer portions 191 to 193 are set to X1 wt%, X2 wt%, and X3 wt% respectively, the relationships of X2 < X1 ≤ X3, and 1 ≤ X1 ≤ X3 ≤ 90, and 0 ≤ X2 are satisfied.

[0278] According to the present modification example, the doping concentration of the second layer portion 192 located between the first and third layer portions 191 and 193 is made the lowest, and thus, it is possible to prevent the light transmissivity from excessively decreasing due to an increase in the Yb doping amount of the entire second functional layer 19.

[0279] Since the doping concentration of the first layer portion 191 is high, the moisture barrier property of NaF of the first functional layer 18 is exhibited while it is also reduced, and thus, it is possible to improve the electron injection property to the light emitting layer.

[0280] In addition, by increasing the concentration of Yb of the third layer portion 193, it is possible to obtain the effects of improving the electron injection property from the cathode side to the second functional layer and preventing moisture from being infiltrated from the outside, and thus, further prolonging the service life of the organic EL element.

[0281] (2) Light resonator structure

[0282] In order to further improve the light emission efficiency, it is preferable to adopt a light resonator structure.

[0283] Figure 14 is a pattern diagram showing a stacked structure in another scheme of the organic EL element 2.

[0284] As shown in Figure 14 , a transparent conductive film 23 having a predetermined film thickness is formed between the second functional layer 19 and the counter electrode 20. The transparent conductive film 23 is formed of ITO, IZO, or the like by a magnetron sputtering method or the like.

[0285] By inserting the transparent conductive film 23, the combination of the counter electrode 20 and the transparent conductive film 23 functions as a cathode, and the thin film resistance is reduced, which contributes to the prevention of a decrease in brightness due to a pressure drop, and since ITO and IZO have high transparency, it is possible to make the film thickness large, and thus, it is possible to be used for adjusting the optical path length of the light resonator structure.

[0286] The film thickness of the transparent conductive film 23 is preferably 15 nm or more. Further preferably, it is 40 nm or more. By making the film thickness of the transparent conductive film 15 nm or more, it is possible to effectively use cavity adjustment (film thickness adjustment for the light resonator structure), and thus, it is possible to improve the efficiency.

[0287] Figure 15 is a view for explaining light interference in the optical resonator structure of the organic EL element 2 in this modification.

[0288] The optical resonator structure is constituted between the interface of the pixel electrode 13 and the hole injection layer 15 and the interface of the counter electrode 20 and the transparent conductive film 23.

[0289] Figure 15 The main light path of the light emitted from the light emitting layer 17 is shown in FIG. 8. The light path Cl is a light path in which the light emitted from the light emitting layer 17 toward the counter electrode 20 side directly transmits through the counter electrode 20 without reflection.

[0290] The light path C2 is a light path in which the light emitted from the light emitting layer 17 toward the pixel electrode 13 side is reflected by the pixel electrode 13 and then transmits through the counter electrode 20 with the light emitting layer 17 interposed therebetween. In this case, the counter electrode 20 is preferably semi-transmissive to reflect a part of the light from below. As described above, such a counter electrode 20 is realized by forming Ag or Al, an alloy thereof, or the like as a material by an evaporation method in a film thickness of 5 nm or more and 30 nm or less.

[0291] The light path C3 is a light path in which the light emitted from the light emitting layer 17 toward the counter electrode 20 side is reflected by the counter electrode 20 and then reflected by the pixel electrode 13, and transmits through the counter electrode 20 with the light emitting layer 17 interposed therebetween.

[0292] The difference (light path difference) AC1 of the optical distances of the light path Cl and the light path C2 corresponds to a length of twice the optical film thickness LI shown in FIG. 8. The optical film thickness LI refers to the total optical distance (the total value of the product of the film thickness and the refractive index of each layer) of the hole injection layer 15 and the hole transport layer 16 between the light emitting layer 17 and the interface of the pixel electrode 13 and the hole injection layer 15. Figure 15 In addition, the light distance difference AC2 of the light path C2 and the light path C3 corresponds to twice the optical film thickness L2 shown in FIG. 8. The optical film thickness L2 refers to the optical distance (the total value of the product of the film thickness and the refractive index of each layer) of the first functional layer 18, the second functional layer 19, and the transparent conductive film 23 between the light emitting layer 17 and the interface of the counter electrode 20 and the transparent conductive film 23.

[0293] Figure 15 In the optical resonator structure, it is necessary to adjust the light after passing through the light path Cl, the light path C2, and the light path C3, respectively, so as to be emitted from the organic EL element 2 in the same phase. Therefore, if the target wavelength of the light emitted in the light path C2 is λ, the light is reflected once and only shifted by half the wavelength in the light path C2, and thus it is preferable that the light path difference AC1 = an integer multiple of λ + λ / 2.

[0294] In the optical resonator structure, it is necessary to adjust the light after passing through the light path Cl, the light path C2, and the light path C3, respectively, so as to be emitted from the organic EL element 2 in the same phase. Therefore, if the target wavelength of the light emitted in the light path C2 is λ, the light is reflected once and only shifted by half the wavelength in the light path C2, and thus it is preferable that the light path difference AC1 = an integer multiple of λ + λ / 2. Figure 15 In the optical resonator structure, it is necessary to adjust the light after passing through the light path Cl, the light path C2, and the light path C3, respectively, so as to be emitted from the organic EL element 2 in the same phase. Therefore, if the target wavelength of the light emitted in the light path C2 is λ, the light is reflected once and only shifted by half the wavelength in the light path C2, and thus it is preferable that the light path difference AC1 = an integer multiple of λ + λ / 2.​

[0295] In this case, any one or two of the film thicknesses of the hole injection layer 15, the hole transport layer 16, and the light emitting layer 17 are set.

[0296] In addition, the light after passing through the optical path C3 needs to be adjusted to be emitted from the organic EL element 2 with the same phase, and therefore, in the optical path C3, the light is reflected twice, and therefore, in this case, it is preferable that the optical path difference ΔC2 = an integer multiple of λ.

[0297] In addition, it is preferable that the above-mentioned optical path difference ΔC1 be determined by the thicknesses and the refractive indexes of the hole injection layer 15 or the hole transport layer 16, but the optical path difference ΔC2 be adjusted by the thickness and the refractive index of the transparent conductive film 23. This is because, as mentioned above, since the transparency of the transparent conductive film 23 is high, even if there is a slight difference in the film thickness of this film, the influence is small. Figure 14

[0298] Since the wavelengths of the respective light emitting colors are different, in order to change the above-mentioned optical path differences ΔC1, ΔC2 in correspondence with the wavelengths, the film thicknesses of the hole injection layer 15, the hole transport layer 16, and the light emitting layer 17 of the organic EL element 2, and the film thickness of the transparent conductive film 23 are determined in correspondence with the respective light emitting colors.

[0299] Needless to say, as mentioned above, since Yb is not easily deteriorated by reacting with moisture, the amount of Yb doped in the second functional layer 19 can be made to be the minimum, and therefore, the transparency is high, and the range of the allowable film thickness is also wide, and therefore, it is also possible to use this instead of or together with the above-mentioned transparent conductive film 23, and set the film thickness in such a way that the optical path difference ΔC2 satisfies the above-mentioned resonance condition.

[0300] In addition, even when a film of ITO or IZO is made on the second functional layer 19 by the sputtering method as the third functional layer, the second functional layer 19 is able to buffer the sputtering damage thereof, and therefore, the light emitting layer is protected, and furthermore, an organic EL element with good light emitting efficiency, and without a shortened service life is obtained.

[0301] Figure 16 An example of an organic EL display panel 10 reflecting this optical resonator structure is shown. In this example, in accordance with the wavelengths of the light emitting colors, the total film thicknesses of the hole injection layer 15, the hole transport layer 16, and the light emitting layer 17 of the organic EL element 2 are sequentially decreased in the order of red (R), green (G), and blue (B) to satisfy the condition of the above-mentioned optical resonance.

[0302] (3) Preventing moisture from penetrating from the outside and reducing the voltage drop due to the film resistance of the counter electrode

[0303] (3-1) Figure 17 is a mode diagram showing the laminated structure in still another scheme of the organic EL element 2. ​

[0304] The difference from the configuration of Figure 14 is that an intermediate layer (Yb layer) 24 composed of Yb is formed between the second functional layer 19 and the transparent conductive film 23.

[0305] Thus, the electron injection property from the opposing electrode 20 is further improved, and when the Yb layer 24, the transparent conductive film 23, and the opposing electrode 20 are regarded as one set of cathode, the overall film resistance is reduced, so even if the size of the organic EL display panel 10 is increased, the voltage drop in the central portion of the screen can be suppressed, and thus a more excellent image quality can be obtained.

[0306] Further, since Yb has a certain water resistance, moisture can be suppressed from being infiltrated from the upper layer (the transparent conductive film 23, the opposing electrode 20, and the sealing layer 21), and further, the deterioration of the lower layer, the second functional layer 19 and the light emitting layer 17, can be prevented, and the service life can be extended.

[0307] Note that the film thickness of the Yb layer 24 is preferably in the range of 0.1 nm or more and 3 nm or less.

[0308] This is because, if it is less than 0.1 nm, the effects of water resistance and reduction of film resistance cannot be expected, and if it exceeds 3 nm, the light transmittance can be affected, and the light emitting efficiency of the organic EL element 2 can be reduced.

[0309] (3-2) Figure 18 is a mode diagram showing the layered structure in still another aspect of the organic EL element 2.

[0310] As shown in Figure 18 , in the present modification example, the Yb layer 24 is formed between the transparent conductive film 23 and the opposing electrode 20. With this configuration, the film resistance of the combination of the opposing electrode 20 and the Yb layer 24 is reduced, and thus the voltage drop is reduced, and even if the size of the organic EL display panel 10 is increased, the voltage drop in the central portion of the screen can be reduced, and thus a more excellent image quality can be obtained.

[0311] Further, the water resistance of Yb can prevent moisture from infiltrating from the upper layer (the opposing electrode 20, the sealing layer 21), and further, the deterioration of the lower layer, the transparent conductive film 23, the second functional layer 19, and the light emitting layer 17, can be suppressed, and the service life can be extended. According to this configuration, the transparent conductive film 23 can also be protected from the influence of external moisture.

[0312] Note that in this modification example, for the same reasons as in the above (3-1), the film thickness of the Yb layer 24 is preferably in the range of 0.1 nm or more and 3 nm or less.

[0313] (3-3) Figure 19is a mode diagram showing the layered structure in still another aspect of the organic EL element 2. As shown in the figure, Figure 19 In this modification, a Yb layer 24 is formed between the sealing layers 21 on the outer side of the counter electrode 20 (the side opposite to the light-emitting layer 17). With this configuration, the pressure drop due to the film resistance of the counter electrode 20 can be reduced, and even if the size of the organic EL display panel 10 is increased, the pressure drop in the central portion of the screen can be suppressed, thereby obtaining a more excellent image quality. Note that the Yb layer 24 is provided more outward than the counter electrode 20, and thus does not have the effect of enhancing the electron injection property.

[0314] Further, the water resistance of the Yb layer 24 can prevent moisture from the upper layer (the sealing layer 21) from permeating, and further suppress the deterioration of the lower layer, i.e., the transparent conductive film 23 and the second functional layer 19, and the light-emitting layer 17, thereby extending the service life.

[0315] In this modification, the film thickness of the Yb layer 24 is preferably in the range of 0.1 nm or more and 5 nm or less. If the film thickness is less than 0.1 nm, the effects of water resistance and reduction of the film resistance cannot be expected, and if the film thickness exceeds 5 nm, the light transmittance is affected, and the emission efficiency of the organic EL element 2 can be reduced.

[0316] (3-4) Figure 20 is a mode diagram showing the layered structure in still another aspect of the organic EL element 2. As shown in the figure, Figure 20 In this modification, a transparent conductive film 23 is formed between the sealing layers 21 on the outer side of the counter electrode 20 (the side opposite to the light-emitting layer 17).

[0317] As is known, in general, when a plurality of transparent films having different refractive indexes are layered, a phenomenon in which a part of light incident on the interface between the adjacent transparent films is reflected occurs at the interface.

[0318] In this modification, for example, the counter electrode 20 is formed of Ag (refractive index 0.05), the transparent conductive film 23 is formed of IZO (refractive index 2.05), and the sealing layer 21 is formed of SiN (refractive index 1.85). Thus, in addition to the interface 20a between the counter electrode 20 and the Yb layer 24, the interface 23a between the counter electrode 20 and the transparent conductive film 23 and the interface 21a between the transparent conductive film 23 and the sealing layer 21 can also form a reflecting surface.

[0319] Thus, by forming cavities (optical resonator structures) in which the optical distance (resonance length) between each interface and the reflecting surface of the pixel electrode 13 is different, light having different peak wavelengths in the spectrum is generated in each cavity, and light having a peak wavelength obtained by synthesizing the above spectra is output from the organic EL element 2.

[0320] Therefore, by appropriately setting the refractive index and film thickness of the counter electrode 20 and the transparent conductive film 23, it is possible to obtain an effect of finely adjusting the chromaticity of the light output. Such a configuration is effective when the peak wavelengths of B or R, G cannot be obtained due to the limitation of the stacked structure and film thickness between the pixel electrode 13 and the counter electrode 20 of the organic EL element 2, and the peak wavelengths are corrected within the ideal wavelength range, and it is possible to improve the color purity of the emission colors of R, G, and B, respectively.

[0321] In addition, since the transparent conductive film 23 is formed of an IZO film as a transparent conductive film and is directly in contact with the counter electrode 20, it is possible to reduce the voltage drop caused by the film resistance of the counter electrode 20, and even if the size of the organic EL display panel 10 is increased, it is possible to suppress the voltage drop in the central portion of the screen, and thus it is possible to obtain a more favorable image quality. The transparent conductive film 23 can also be another transparent conductive film such as an ITO film.

[0322] Note that, instead of the Yb layer 24 in the above (3-1) to (3-4), a single layer or a plurality of layers of rare earth metal layers including another rare earth metal can be included.

[0323] (4) Modification of the formation process of the barrier ribs and the pixel confinement layer

[0324] Although in the above embodiment, the barrier ribs 14 and the pixel confinement layer 141 are formed by different processes, it is also possible to simultaneously form the barrier ribs 14 and the pixel confinement layer 141 using a half-tone mask.

[0325] First, a resin material is applied to the interlayer insulating layer 12 on which the pixel electrode 13, the hole injection layer 15 are formed, by a wet process such as a die coater method, to form a barrier rib material layer 140 (see FIG. 13 (c)). Figure 5

[0326] After the application, it is preferable to perform, for example, vacuum drying and low-temperature heating drying (pre-baking) at 60°C to 120°C or the like to remove the excess solvent and fix the barrier rib material layer to the interlayer insulating layer 12.

[0327] Next, the barrier rib material layer 140 is exposed through a photomask (not shown).

[0328] For example, in the case where the barrier rib material layer 140 has positive photosensitivity, the portion of the barrier rib material layer 140 to be left is shielded from light, and the portion to be removed is exposed.

[0329] Since the film thickness of the pixel confinement layer 141 is smaller than that of the barrier ribs 14, the portion of the pixel confinement layer 141 needs to be half-exposed to the barrier rib material layer 140.

[0330] ​Therefore, a halftone mask is used as the photomask in the exposure process. The halftone mask has: a light-blocking portion that is provided at a position corresponding to the partition 14 and completely blocks light; a semi-transparent portion that is provided at a position corresponding to the pixel confinement layer 141; and a light-transmitting portion that is provided at a position corresponding to the exposed portion of the additional pixel electrode 13.

[0331] The light transmittance of the aforementioned semi-transparent portion is determined such that, after a predetermined exposure time, the partition material layer 140 on the pixel electrode 13 is fully exposed, while the height portion of the pixel confinement layer 141 is retained and not exposed.

[0332] Next, development is performed to remove the exposed areas of the partition material layer 140, thereby forming the partition 14 and the pixel confinement layer 141 with a film thickness smaller than the partition 14. As a specific development method, for example, the substrate 11 can be immersed entirely in a developer solution such as an organic solvent or an alkaline solution, and then the substrate 11 can be cleaned with a rinsing solution such as purified water. In this process, the developer dissolves the photosensitive portions of the partition material layer 140. Then, firing is performed at a predetermined temperature.

[0333] As described above, by using a halftone mask, the partition 14 extending in the Y direction and the pixel confinement layer 141 extending in the X direction can be formed on the interlayer insulating layer 12 through the same process, thereby reducing the number of processes and thus helping to reduce the manufacturing cost of the organic EL display panel.

[0334] (5) Variations of the stacked structure of organic EL elements

[0335] In the above embodiments, the organic EL element is stacked with a first functional layer 18 and a second functional layer 19, a hole injection layer 15 and a hole transport layer 16, but is not limited thereto. For example, an organic EL element without a hole transport layer 16 may also be used. Alternatively, for example, a single hole injection transport layer may be used instead of the hole injection layer 15 and the hole transport layer 16.

[0336] (6) In the organic EL display panel 10 of the above embodiment, as Figure 2 As shown, the pixel confinement layer 141 extends in the direction of the major axis X of the organic EL display panel 10, and the partition wall 14 extends in the direction of the minor axis Y of the organic EL display panel 10. However, the extension directions of the pixel confinement layer 141 and the partition wall 14 can also be opposite. In addition, the extension directions of the pixel confinement layer and the partition wall can also be directions independent of the shape of the organic EL display panel 10.

[0337] In addition, in the organic EL display panel 10 of the above embodiment, the image display surface is made into a rectangle by way of example, but the shape of the image display surface is not limited and can be changed appropriately.

[0338] In addition, in the organic EL display panel 10 of the above embodiment, the pixel electrode 13 is made into a rectangular flat plate-shaped member, but is not limited thereto.

[0339] (7) In the above embodiment, the hole injection layer 15 is formed by a dry process, but it is also possible to form the pixel confinement layer 141 and the partition wall 14 after the pixel electrode 13 is formed, and then, as shown in (a), form the hole injection layer 15 in the opening portions 14a of the adjacent partition walls 14 from each other by a wet process. Figure 21

[0340] In this case, regarding the film shape of the hole injection layer 15, since the position P3 at which the partition wall 14 is in contact with the hole injection layer 15 is located more upward than the central flat portion, it is possible to easily know that the hole injection layer 15 is also a coating film formed by a wet process. Figure 21

[0341] (8) In the organic EL display panel 10 of the above embodiment, the sub-pixels 100R, 100G, 100B which respectively emit light of R, G, B colors are arranged, but the light emission colors of the sub-pixels are not limited thereto, and it is also possible to be, for example, four colors of R, G, B, and yellow (Y). In addition, in one pixel P, the sub-pixels are not limited to one for each color, but a plurality of them can be arranged. In addition, the arrangement of the sub-pixels in the pixel P is not limited to the order of red, green, and blue as shown in (a), but can be in a reversed order. Figure 2

[0342] (9) In the above embodiment, the organic EL display panel 10 of the line-shaped bump method is described. Figure 22 (a) shows a schematic partial perspective view of a stage after the pixel confinement layer 141 and the partition wall 14 are formed in the organic EL display panel 10 of the line-shaped bump method.

[0343] Since the height of the pixel confinement layer 141 for defining the range of the sub-pixel in the Y direction is lower than that of the partition wall 14, when the ink is continuously applied to the opening portion 14a, it has an advantage that the ink easily flows in the Y direction to be uniform in film thickness by leveling, but on the other hand, it has a disadvantage that the contact area of the light emitting layer 17 and the first functional layer 18 formed by a wet process becomes large, and moisture easily penetrates into the upper layer.

[0344] Figure 22 (b) is a partial perspective view schematically showing the shape of the partition wall 14 in the pixel bump method. It has the following advantages: Figure 22 ​​​(b) The four sides of each sub-pixel are covered by the higher barrier 14, so the light emitting layer 17 cannot further expand, and accordingly, the contact area of the first functional layer 18 and the light emitting layer 17 is limited compared to the linear bump method, and the amount of moisture that can possibly penetrate the first functional layer 18 is reduced, and further, the deterioration of the first functional layer 18 and the second functional layer 19 is suppressed, and in these respects, the present application is superior to the linear bump method.

[0345] (10) In addition, the present application can be applied not only to a top emission type organic EL display panel, but also to a bottom emission type organic EL display panel.

[0346] Figure 23 is a schematic cross-sectional view showing the layer structure of a bottom emission type organic EL display panel. As compared with the top emission type organic EL display panel 10 explained in Figure 3 the following differences exist.

[0347] (a) The counter electrode 20 does not need to be transparent, but only needs to be reflective.

[0348] Thus, the film thickness of the counter electrode 20 can be increased, or a material with high conductivity can be used, so that the film resistance is reduced, and thus, the brightness unevenness caused by the voltage drop of the counter electrode 20 can be eliminated. In addition, with the increase in film thickness, the sealing effect of the counter electrode 20 is expected to be improved.

[0349] (b) The pixel electrode 13 is formed of a transparent conductive film such as IZO and ITO, and the interlayer insulating layer 12 is formed of a transparent resin material. In addition, on the TFT layer 112, a driving circuit of the light emitting element using a TFT is formed in a first region 1121 overlapping the barrier 14 (or the pixel restricting layer 141) in plan view, and a second region 1122 therebetween is made to have light transmissivity, so as to prevent the emission light from being blocked. The substrate 111 is also formed of a light transmissive resin sheet or a glass sheet.

[0350] In addition, the counter electrode 20 can be used as a light reflective anode, and the pixel electrode 13 can be formed of a light transmissive (including semi-light transmissive) material and used as a cathode. Accordingly, the layer stacking order of the other hole injecting layer 15, the hole transporting layer 16, the first functional layer 18, and the second functional layer 19 is opposite to that shown in Figure 23 , but in this case, the thickness of the substrate 111 is thick, so that the sealing property is very high, and the second functional layer 19 is less likely to deteriorate.

[0351] In addition, in the case where a color filter substrate and a polarizing sheet are provided, if they are attached to the substrate 11, or the substrate 11 itself is used as the color filter substrate and the polarizing sheet, the constitution can be simplified, and the cost can be reduced.

[0352] It is to be noted that, in the bottom emission type organic EL display panel, by making the counter electrode 20 also transparent, a transmissive organic EL display panel can be provided. For example, by providing the transmissive organic EL display panel 10 on the windshield of a vehicle, a guide screen for vehicle navigation and a speedometer of an automobile, etc. can be displayed without blocking the view of the front, so as not to affect driving, and further the application field of the organic EL display panel 10 can be expanded.

[0353] (11) Development of flexible display panel

[0354] With diversification of the use of the organic EL display panel 10, higher flexibility is gradually required.

[0355] In the above embodiment, the sealing layer 21 is formed in a single layer using a light-transmissive inorganic material such as silicon nitride (SiN) and silicon oxynitride (SiON), which has excellent sealing properties, but has the disadvantage that cracks are easily generated by external force and is not resistant to bending action. If the film thickness of the inorganic material sealing layer is increased in order to prevent generation of cracks, the rigidity increases, greatly impairing flexibility.

[0356] Thus, recently, research has been conducted to absorb the impact of external force by reducing the film thickness of the inorganic material layer in the sealing layer and laminating a resin material layer, to prevent generation of cracks while ensuring flexibility.

[0357] Figure 24 is a mode diagram showing an example of the laminated structure of the organic EL display panel (flexible display panel) 400 having excellent flexibility in the present modification example.

[0358] As shown in Figure 24 , the flexible display panel 400 includes a substrate 411, an interlayer insulating layer 412, a light emitting main portion 430, and a sealing layer 421.

[0359] The substrate 411 is formed by forming a UC (undercoat layer) layer 4112 on a resin film 4111 as a base material, and forming a TFT layer 4113 on the UC layer 4112.

[0360] The resin film 4111 is preferably composed of a resin material having flexibility and excellent heat resistance. In the present modification example, PET (polyethylene terephthalate) is used.

[0361] However, compared to the base material of a glass sheet, the resin film 4111 has a high moisture absorption rate and transmittance, and thus a thin UC layer 4112 composed of an inorganic material such as SiN and SiON is laminated on the resin film 4111 to block moisture from being infiltrated from below, thereby preventing the TFT layer 4113 from being deteriorated by moisture.

[0362] The light-emitting main portion 430 is provided on the substrate 411 with the interlayer insulating layer 412 interposed therebetween. In the present modification, the light-emitting main portion 430 has the same stacked structure as the light-emitting main portion in the embodiment (see FIG. 2) and is formed of a hole injection layer 415, a hole transport layer 416, a light-emitting layer 417, a first functional layer 418, a second functional layer 419, and a counter electrode 420, which are sequentially stacked on the pixel electrode 413. The contents of these components are the same as those described in the embodiment, and thus the detailed contents are omitted. Figure 9

[0363] The counter electrode 420 of the light-emitting main portion 430 is provided with a sealing layer 421. The sealing layer 421 is a three-layer structure of a first sealing layer 4211, a second sealing layer 4212, and a third sealing layer 4213.

[0364] The first sealing layer 4211 is formed of a light-transmissive inorganic material such as SiN or SiON by a dry process such as sputtering or CVD, and the second sealing layer 4212 is formed of a light-transmissive resin material such as fluorine-based or acrylic, epoxy-based, or the like on the first sealing layer 4211 by a wet process such as a coating method. The third sealing layer 4213 is formed on the second sealing layer 4212 by the same method as the first sealing layer 4211.

[0365] Thus, even if the film thickness of the first sealing layer 4211 and the third sealing layer 4213, which are formed of inorganic materials, is reduced, the second sealing layer 4212, which is formed of a resin material, can buffer external force, and thus a crack is less likely to occur, and flexibility and sealing properties can be ensured.

[0366] As described above, the base material of the substrate is formed of a resin film, and the sealing layer is formed by interposing a film formed of a resin material (organic material layer) between two thin films formed of inorganic materials (inorganic material layers), and thus flexibility and sealing properties can be ensured. In a display panel having such a configuration, the water resistance is increased by using Yb as the doping metal of the second functional layer 419 as in the above-described embodiment, and thus the sealing layer 421 can also be provided with sufficient durability by, for example, sequentially stacking inorganic films and organic films. Thus, the sealing structure of the flexible display panel 400 can be simplified.

[0367] In addition, such a flexible display panel is particularly easy to install in a car, which is frequently bent. Also, in a case of a hot summer day or the like, the inside of the car can be high in temperature, but the rare earth metal mainly including Yb has a higher standard reduction potential than Ba (barium) or the like, which is conventionally used as a doping metal, and thus even if the temperature is slightly increased, the chemical stability is maintained, and the reaction with impurities such as moisture is less likely to occur, and thus the high-temperature durability can be increased, and the display panel can be used for a long time in a severe temperature environment.

[0368] ​Note that a publicly known resin film-based polarizing plate (more specifically, a linear polarizing plate and a circular polarizing plate formed by combining a 1 / 4 wavelength plate) can be further attached to the sealing layer 421. With this, it is possible to prevent light incident from the outside into the inside of the flexible display panel 400 from being reflected inside and emitted to the outside, and in particular, it is possible to improve the visibility of a display image of the flexible display panel 400 outdoors. In addition, it is also possible to suppress the intrusion of impurities such as moisture from the outside.

[0369] In addition, in a case where a color filter is mounted in order to adjust the emission color, a publicly known on-cell color filter (OCCF) is preferably used. There is a strong demand for high definition of pixels of an organic EL display panel and miniaturization of a frame region (a region around an emission region which does not participate in emission), and in particular, in order to achieve high definition of pixels, it is necessary to make the positional deviation of the light emitting element and the color filter smaller. Therefore, an on-cell color filter structure formed directly on the sealing layer (for example, see Japanese Patent Application Publication No. 2012-38677) is preferably used instead of forming the color filter on a counter substrate provided on the sealing layer and then aligning. With this, in particular, even if the flexible display panel is made into a desired shape, the color filter and the pixels are less likely to be deviated in position.

[0370] Note that the main light emitting portion 430 of the flexible display panel 400 of the present modification is not limited to the configuration shown in FIG. 4, but can be widely applied and includes all the configurations described in the present modification. Figure 9

[0371] (12) Tandem Organic EL Element

[0372] In order to further improve the emission efficiency or emit a color of a plurality of colors, a so-called tandem organic EL element in which two or more light emitting layers are formed between an anode and a cathode and a charge generation layer is formed between the light emitting layers is proposed.

[0373] The present application can also be applied to such a tandem organic EL element.

[0374] Figure 25 FIG. 5 is a schematic view showing the stacked structure of the main portion of the tandem organic EL element 500, but the substrate and the sealing layer are omitted in the figure.

[0375] Figure 25 The organic EL element in the present modification has, in order, an anode (pixel electrode) 501, a hole injection / transport layer 502, a light emitting layer 503, a NaF layer (first functional layer) 504, a Yb-doped layer (second functional layer) 505, a charge generation layer 506, a hole injection / transport layer 507, a light emitting layer 508, a NaF layer (first functional layer) 509, a Yb-doped layer (second functional layer) 510, and a cathode (counter electrode) 511.​

[0376] In the present example, the charge generation layer 506 located in the middle is formed of a P-type inorganic oxide such as MoO3, and has a function of providing holes to the hole injection transport layer 507 and providing electrons to the Yb-doped layer 505.

[0377] Note that, in the present example, the light emitting layer 503 emits B color (blue) light, and the light emitting layer 508 emits Y color (yellow) light. Blue and yellow have a substantially complementary relationship, and thus, when combined, the final emitted color is close to white. The combination of light emitting colors is not limited to this, and other light emitting colors can be freely combined to output a desired color of light.

[0378] In this tandem organic EL element 500, the electron injection property and durability can be improved by the combination of the Yb-doped layer and the NaF layer, which contributes to the improvement of the light emission efficiency and the extension of the service life.

[0379] (13) The organic EL display panel shown in the above-described embodiments can be used as a display panel of a television device 600 shown in FIG. 12, and other various electronic devices such as personal computers, mobile terminals, and commercial displays. Figure 26

[0380] (14) The organic EL display panel 10 in the above-described embodiments employs an active matrix method, but is not limited to this, and can employ a passive matrix method.

[0381] (15) In the above-described embodiments, the manufacturing method of the organic EL display panel using an organic EL as a light emitting layer is described, but in a display panel such as a quantum dot display panel (see, for example, Japanese Patent Application Publication No. 2010-199067) using a quantum dot light emitting element (QLED: Quantum dot Light Emitting Diode) as a light emitting layer, only the structure and kind of the light emitting layer are different, and the constitution of the light emitting layer and other functional layers between the pixel electrode and the counter electrode is the same as that of the organic EL display panel, and in the case where the light emitting layer and other functional layers are formed by a coating method, the present application can be applied.

[0382] <Supplement>

[0383] ​The organic EL element, the method for manufacturing the organic EL element, the organic EL display panel, the organic EL display device, and the electronic device described above are based on the embodiments and modifications, but the present application is not limited to the above-described embodiments and modifications. The present application also includes a solution obtained by applying various modifications to the above-described embodiments and modifications, and a solution obtained by arbitrarily combining the components and functions in the embodiments and modifications within a range not departing from the gist of the present application.

[0384] Industrial Applicability

[0385] The self-light-emitting element of the present disclosure can be widely used in display panels used in various electronic devices.

[0386] Explanation of Symbols

[0387] 1, organic EL display device; 2, organic EL element; 10, organic EL display panel; 11, 411, substrate; 12, 412, interlayer insulating layer; 13, 413, pixel electrode; 14, partition wall; 15, 415, hole injection layer; 16, 416, hole transport layer; 17, 417, light-emitting layer; 18, 418, first functional layer; 19, 419, second functional layer; 20, 420, counter electrode; 21, 421, sealing layer; 4211, first sealing layer; 4212, second sealing layer; 4213, third sealing layer; 23, transparent conductive film; 24, Yb layer; 100B, 100G, 100R, sub-pixel; 111, 4111, base material; 112, 4113, TFT layer; 4112, UC layer; 140, partition wall material layer; 141, pixel confinement layer; 191, first layer portion; 192, second layer portion; 193, third layer portion.

Claims

1. A self-light-emitting element provided with a light-emitting layer between an anode and a cathode, characterized in that, The self-light-emitting element includes: a first functional layer provided between the light-emitting layer and the cathode, which contains a fluoride of a metal selected from alkali metals, alkaline earth metals, or rare earth metals; and a second functional layer provided between the first functional layer and the cathode, which contains a rare earth metal as a dopant material, the second functional layer includes a first layer portion provided on the first functional layer and a second layer portion provided on the first layer portion, a content ratio of the rare earth metal in the second layer portion is greater than a content ratio of the rare earth metal in the first layer portion, the second functional layer is in contact with the first functional layer, and the second functional layer is formed using an organic material having electron-transport properties as a host material and a rare earth metal as a dopant material.

2. A self-emissive element, wherein a light-emitting layer is disposed between an anode and a cathode, characterized in that, The self-light-emitting element includes: a first functional layer provided between the light-emitting layer and the cathode, which contains a fluoride of a metal selected from alkali metals, alkaline earth metals, or rare earth metals; and a second functional layer provided between the first functional layer and the cathode, which contains a rare earth metal as a dopant material, the second functional layer is formed by sequentially stacking a first layer portion, a second layer portion, and a third layer portion from the side closer to the first functional layer, and if content ratios of the rare earth metal in the first layer portion, the second layer portion, and the third layer portion are denoted by X1, X2, and X3, respectively, X2 < X1 ≤ X3.

3. A self-emissive element, wherein a light-emitting layer is disposed between an anode and a cathode, characterized in that, The self-light-emitting element includes: a first functional layer provided between the light-emitting layer and the cathode, which contains a fluoride of a metal selected from alkali metals, alkaline earth metals, or rare earth metals; and a second functional layer provided between the first functional layer and the cathode, which contains a rare earth metal as a dopant material, a content of the rare earth metal in the second functional layer continuously increases from the first functional layer toward the cathode, the second functional layer is in contact with the first functional layer, and the second functional layer is formed using an organic material having electron-transport properties as a host material and a rare earth metal as a dopant material.

4. The self-light-emitting element according to any one of claims 1 to 3, wherein a film thickness of the first functional layer is greater than or equal to 0.1 nm and less than or equal to 20 nm.

5. The self-light-emitting element according to any one of claims 1 to 4, wherein a film thickness of the second functional layer is greater than or equal to 5 nm and less than or equal to 150 nm.

6. The self-light-emitting element according to any one of claims 1 to 4, wherein a transparent conductive film is formed between the second functional layer and the cathode as a third functional layer.

7. The self-light-emitting element according to claim 6, wherein a film thickness of the third functional layer is greater than or equal to 15 nm.

8. The self-light-emitting element according to claim 6, wherein a thin film containing a rare earth metal having a film thickness greater than or equal to 0.1 nm and less than or equal to 3 nm is formed between the second functional layer and the third functional layer.

9. The self-light-emitting element according to claim 6, wherein a thin film containing a rare earth metal having a film thickness greater than or equal to 0.1 nm and less than or equal to 3 nm is formed between the third functional layer and the cathode.

10. The self-light-emitting element according to any one of claims 1 to 4, wherein a thin film containing a rare earth metal is formed on the side of the cathode opposite to the light-emitting layer, and has a thickness of greater than or equal to 0.1 nm and less than or equal to 5 nm.

11. The self-light-emitting element according to any one of claims 1 to 4, wherein the anode has light reflectivity, and the cathode has semi-transmittivity.

12. The self-light-emitting element according to claim 11, wherein light emitted in the light-emitting layer includes first light beams directly emitted from the cathode, and second light beams emitted from the cathode after being reflected by the surfaces of the light-emitting layer side of the anode and the cathode, respectively, and the thickness of at least one functional layer between the light-emitting layer and the cathode is set in accordance with the wavelength of the color of light emitted from the self-light-emitting element, so that the first light beams and the second light beams resonate.

13. The self-light-emitting element according to any one of claims 1 to 4, wherein at least one functional layer between the anode and the cathode is a coated film.

14. The self-light-emitting element according to any one of claims 1 to 4, wherein the fluoride of a metal selected from the alkali metal, the alkaline earth metal, or the rare earth metal is NaF.

15. The self-light-emitting element according to any one of claims 1 to 4, wherein the rare earth metal is Yb.

16. A self-light-emitting display panel, comprising: a plurality of self-light-emitting elements according to any one of claims 1 to 15 arranged in a matrix over a substrate, and the light-emitting layers of self-light-emitting elements adjacent to each other in at least a row direction are separated by a partition extending in a column direction.

17. The self-light-emitting display panel according to claim 16, wherein the self-light-emitting display panel is a top emission type.

18. A self-light-emitting display device, comprising: the self-light-emitting display panel according to claim 16 or 17; and a driving unit that drives the self-light-emitting display panel to display an image.

19. An electronic device, comprising the self-light-emitting display device according to claim 18 as an image display unit.

20. A method for manufacturing a self-luminous element, characterized by: is a method for manufacturing a self-light-emitting element according to any one of claims 1 to 3, the method for manufacturing a self-light-emitting element comprising: a first step of forming an anode; a second step of forming a light-emitting layer over the anode; a third step of forming a first functional layer containing a fluoride of a metal selected from an alkali metal, an alkaline earth metal, or a rare earth metal over the light-emitting layer; a fourth step of forming a second functional layer in which a rare earth metal is used as a dopant material over the first functional layer; and a fifth step of forming a cathode over the second functional layer.

21. The method for manufacturing a self-light-emitting element according to claim 20, wherein the fourth step includes doping the rare earth metal into an organic material layer formed over the first functional layer to form the second functional layer.

22. The method for manufacturing a self-light-emitting element according to claim 20, wherein the fourth step includes simultaneously evaporating an organic material and the rare earth metal over the first functional layer to form the second functional layer.

23. A method of manufacturing a self-luminous element according to any one of claims 20 to 22, characterized by, Further comprising, between the first process and the second process, a process of forming a hole-transporting layer having a hole-transporting function, the process of forming the hole-transporting layer and at least one of the second process, the third process, and the fourth process being performed by a wet process.

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