Organic electroluminescence devices using transparent metal grid electrodes

Abstract

To provide an organic electroluminescent element capable of suppressing problems such as delamination, the organic electroluminescent element being mounted with a metal grid transparent conductive electrode comprising metal wiring, such as a convex thin metal wire, that contains an oxide such as a metal oxide with low acid resistance, and that further has a film thickness greater than the conventional average film thickness.SOLUTION: A metal grid transparent conductive electrode 20 includes a transparent base material 22 and a conductive pattern 24P comprising metal wiring 24 provided on the transparent base material 22. The metal wiring 24 includes a metal and an oxide of the metal. An organic functional layer 40 includes: a doped hole injection layer 42 provided on the conductive pattern 24P and comprising a low molecular organic material; and a hole transport layer 44 provided on the doped hole injection layer 42 and comprising a low molecular organic material. When tTCE represents the thickness of the metal wiring 24 and torg-TCE represents the film thickness of the organic functional layer 40, tTCE is 50 nm or more and 250 nm or less, and (torg-TCE-tTCE) is 50 nm or more and 750 nm or less.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an organic electroluminescence element using a metal grid transparent electrode that can suppress electrical shorts and leakage currents and further improve brightness. [Background technology]

[0002] In recent years, organic electroluminescence elements (hereinafter also referred to as "organic EL elements") have begun to be applied to flat-screen televisions, smartphones, lighting, etc. Organic EL elements have a configuration in which an organic functional layer, including at least an organic light-emitting layer, is disposed between two opposing electrodes. Since light emitted from the organic light-emitting layer passes through the electrodes and is extracted to the outside, at least one of the electrodes is called a transparent electrode (hereinafter also referred to as "TCE"), which is an essential constituent technology for organic EL elements. To further expand the applications of organic EL elements, there is a demand for larger areas, lighter weight, and more flexibility, and therefore a low-resistance, flexible transparent electrode is required.

[0003] Conventionally, transparent electrodes using a film made of indium tin oxide (hereinafter also referred to as "ITO") formed on a transparent substrate by vacuum deposition or sputtering have been widely used.

[0004] However, while ITO itself is a highly transparent material, it has low electrical conductivity. Therefore, to achieve low resistance, it is necessary to thicken the ITO film, which leads to the problem of reduced transmittance. Furthermore, thicker films make cracks more likely to occur when bent, flexed, or otherwise deformed. For this reason, it has been difficult to increase the area and flexibility of organic EL elements that use ITO as a transparent electrode.

[0005] Therefore, research and development into transparent electrodes to replace ITO has been actively pursued, and transparent electrodes with a conductive pattern of fine metal wires on a transparent substrate (hereinafter referred to as "metal grid transparent electrodes" or "metal grid TCE") have attracted attention. Metal grid transparent electrodes are more flexible than ITO, which is an oxide, due to the high ductility of the metal wires. Furthermore, because the electrical conductivity of the metal wires is higher than that of ITO, metal grid transparent electrodes have lower sheet resistance than transparent electrodes using ITO when compared at the same transmittance. Furthermore, metal grid transparent electrodes have the advantage that their properties, such as transmittance and sheet resistance, can be freely adjusted by adjusting the wire width and film thickness of the metal wires and the gaps in the conductive pattern. Furthermore, although the metal wires themselves are opaque, adjusting the wire width to 3 μm or less makes them invisible to the human eye, further improving the transparency of metal grid transparent electrodes.

[0006] Conventionally, metal grid transparent electrodes made of fine metal wires have been manufactured by vacuum deposition of a metal vapor-deposited film and then patterning it using photolithography, which has resulted in problems of high cost and low productivity.

[0007] Against this background, high-resolution printing technologies have been developed in recent years that can form extremely fine metal wires with widths of 3 μm or less, even submicron, on transparent substrates. Such additive high-resolution printing technologies can be easily adapted to roll-to-roll processes, enabling high industrial productivity and reducing environmental impact.

[0008] However, when a metal grid transparent electrode is used in an organic EL device, it is difficult to cover the convex thin metal wires with the organic functional layer because the typical organic functional layer is a thin film of 100 to 200 nm due to its lower carrier mobility compared to inorganic semiconductor materials, which makes it more likely to cause an electrical short circuit due to contact between the thin metal wires and the opposing cathode, or an increase in leakage current due to a shorter distance between the two electrodes.

[0009] To address this issue, a structure has been proposed in which a transparent conductive inorganic compound such as ITO or ZnO is layered on a conductive pattern and then coated with thin metal wires to smooth out the irregularities of the conductive pattern (see, for example, Patent Document 1).A structure in which a transparent conductive inorganic compound is layered on a conductive pattern made of thin metal wires cannot be expected to provide sufficient flexibility.

[0010] Similarly, a structure has been proposed in which a conductive polymer, such as poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (hereinafter also referred to as "PEDOT:PSS"), is laminated on a conductive pattern as a transparent conductive or hole injection layer, and then coated with thin metal wires to smooth the unevenness of the conductive pattern (see, for example, Patent Documents 1 and 2, and Non-Patent Documents 1 and 2). Non-Patent Documents 1 and 2 disclose organic EL devices using a metal grid transparent electrode with convex silver or copper thin metal wires with a line width of 3 μm or less, which are manufactured by vacuum deposition and photolithography. These Non-Patent Documents also smooth the unevenness of the conductive pattern using a hole injection layer made of PEDOT:PSS, thereby realizing an organic EL device with low leakage current. A layer made of a typical conductive polymer can be formed, for example, by preparing a coating solution in which PEDOT:PSS is dispersed in an aqueous solvent, printing or coating this coating solution on a conductive pattern, and drying it. The aqueous coating solution of PEDOT:PSS exhibits strong acidity due to the sulfo group of PSS contained in it to stably disperse the conductive component PEDOT in the aqueous solvent.

[0011] Furthermore, Patent Document 1 discloses that by providing a metal adhesion layer made of a metal oxide such as TiO2 or ZnO between a substrate and thin metal wires printed using ink containing metal nanoparticles, the adhesion between the thin metal wires and the substrate is improved, and peeling of the thin metal wires is suppressed during the manufacturing process up to the time the thin metal wires are covered with a transparent conductive layer such as PEDOT:PSS, and during use. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] International Publication No. 2016 / 147481 [Patent Document 2] International Publication No. 2016 / 143201 [Patent Document 3] International Publication No. 2020 / 027166 [Non-patent literature]

[0013] [Non-Patent Document 1] FLM Sam et al., Silver grid transparent conducting electrodes for organic light emitting diodes, Org. Electron., December 2014, Vol. 15, P. 3492-3500 [Non-patent document 2] JW Han et al., Transparent conductive hybrid thin-films based on copper-mesh / conductive polymer for ITO-Free organic light-emitting diodes, Org. Electron., October 2019, Vol. 73, P. 13-17 [Non-patent document 3] Peter van de Weijer et al., High-performance thin-film encapsulation for organic light-emitting diodes, Org. Electron., May 2017, Vol. 44, P. 94-98 Summary of the Invention [Problem to be solved by the invention]

[0014] However, the inventors' investigations have revealed that when a strongly acidic aqueous coating solution of PEDOT:PSS is printed or applied to thin metal wires containing certain metal oxides, such as copper oxide, which have low acid resistance, problems occur, such as the thin metal wires being damaged or peeling off from the transparent substrate.For example, the mechanism by which cupric oxide, a form of copper oxide, dissolves in an aqueous solution containing an organic sulfonic acid such as PSS can be explained by the following reaction formula. [ka]

[0015] Therefore, it was found that it is difficult to mount a metal grid transparent electrode having thin metal wires containing metal oxides with low acid resistance on an organic EL device.

[0016] Furthermore, because thin metal wires formed by printing are formed by contacting and / or bonding nanostructures originating from metal nanoparticles, their resistivity tends to be, for example, 10 to 20 times higher than that of thin metal wires made of a single metal using vacuum deposition. Therefore, to reduce sheet resistance, it is necessary to adjust the film thickness (i.e., the height of the convex portions) of the convex thin metal wires to a larger range than conventional methods. This makes it even more difficult to incorporate metal grid transparent electrodes formed by printing into organic EL devices due to the risk of electrical shorts and increased leakage current.

[0017] The present invention has been made in view of the above-mentioned problems, and aims to provide an organic EL element that can suppress the above-mentioned problems such as peeling in an organic EL element that includes an oxide such as a metal oxide having low acid resistance and that is made of metal wiring such as convex thin metal wires having a thickness greater than the average thickness of a conventional organic EL element, and that can further improve brightness. [Means for solving the problem]

[0018] The present inventors have conducted extensive research to solve the above problems, and as a result have found that the above problems can be solved by providing an organic functional layer with a doped hole injection layer and a hole transport layer made of a low-molecular-weight organic material, disposing the doped hole injection layer on a conductive pattern of a metal grid transparent electrode, and further increasing the thickness of the doped hole injection layer and the hole transport layer so that the total film thickness of the organic functional layer is greater than the film thickness of the thin metal wires, thereby completing the present invention.

[0019] That is, the present invention is as follows. [1] An organic electroluminescence element comprising a metal grid transparent electrode, a cathode facing the metal grid transparent electrode, and an organic functional layer provided between the metal grid transparent electrode and the cathode, wherein the metal grid transparent electrode comprises a transparent substrate and a conductive pattern having metal wiring provided on the transparent substrate, the metal wiring comprising a metal and an oxide of the metal, the organic functional layer comprising a doped hole injection layer provided on the conductive pattern and made of a low-molecular organic material, and a hole transport layer provided on the doped hole injection layer and made of a low-molecular organic material, and further comprising t TCE is the thickness of the metal wiring, and t org-TCE When the thickness of the organic functional layer is t TCE is 50 nm or more and 250 nm or less, and ( t org-TCE -t TCE ) is between 50 nm and 750 nm. [2] In the organic electroluminescence element, W TCE is the line width of the metal wiring, and G TCE is the gap between adjacent metal wirings extending in the same direction, W TCE may be 0.25 μm or more and 5.0 μm or less. G TCE may be 50 μm or less. (G TCE / W TCE ) must be 1.0 or greater.

[0020] [3] In the organic electroluminescence element, A TCEis the aperture ratio of the conductive pattern, (G TCE * A TCE ) may be between 0.6 μm·% and 30 μm·%. [4] In the organic electroluminescence element, the aperture ratio A of the conductive pattern TCE may be between 35% and 100%. [5] In the organic electroluminescence element, t HIL is the thickness of the doped hole injection layer, t HIL may be 30 nm or more and 200 nm or less. [6] In the organic electroluminescence element, t HTL is the thickness of the hole transport layer, t HTL may be 30 nm or more and 200 nm or less. [7] In the organic electroluminescence element, σ HIL is the electrical conductivity of the doped hole injection layer, σ HIL is 5 x 10 -5 S / cm or higher is sufficient. [8] In the organic electroluminescence element, the sheet resistance of the doped hole injection layer is 6.5×10 9 Ω / sq. or less is sufficient. [9] In the organic electroluminescence element, the visible light transmittance of the doped hole injection layer may be 80% or more and 100% or less.

[10] In the organic electroluminescence element, the dopant density N p may be 3 vol% or more and 18 vol% or less.

[11] The organic electroluminescence device may further include a transparent conductive inorganic compound layer disposed between the metal grid transparent electrode and the dope hole injection layer.

[12] In the organic electroluminescence element, the transparent conductive inorganic compound layer may contain indium tin oxide.

[13] In the organic electroluminescence element, the metal grid transparent electrode may include a current collecting portion having a second conductive pattern provided on the transparent substrate and electrically connected to the conductive pattern.

[0021] Also S Bus is the occupied area ratio of the second conductive pattern per unit area, S Bus may be between 50% and 100%.

[14] In the organic electroluminescence element, the metal may be copper.

[15] In the organic electroluminescence element, in a STEM-EDX analysis of a cross section of the metal wiring of the conductive pattern perpendicular to the extending direction of the metal wiring, TCE ~0.90t TCE The atomic % ratio O / M of oxygen atoms contained in the oxide of the metal to the metal in the thickness region up to 0.10 ~ 0.90 may be set to 0.01 or more and 1.00 or less.

[16] In the organic electroluminescence element, the conductive pattern may have a mesh pattern.

[17] In the organic electroluminescent element, the conductive pattern may be formed by printing an ink containing the metal on the surface of the transparent substrate in a plate-based printing process to form the conductive pattern, and then baking the printed ink in a baking process to fuse the metal to form a metal component sintered film.

[18] In the organic electroluminescence element, the doped hole injection layer may be made of two or more low-molecular organic materials.

[19] In the organic electroluminescence element, the doped hole injection layer has a dopant density N p Alternatively, the low molecular weight host material and the low molecular weight dopant may be co-evaporated so that the content of the low molecular weight host material and the low molecular weight dopant is 3 vol % or more and 18 vol % or less.

[20] In the organic electroluminescence element, each layer constituting the organic functional layer may be formed of a low molecular weight organic material.

[21] The organic electroluminescent element may include a second transparent conductive inorganic compound layer disposed on the transparent substrate, and the metal grid transparent electrode may be disposed on the second transparent conductive inorganic compound layer.

[0022] In the organic electroluminescence element, the metal wiring may be provided in a convex shape that contacts the surface of the transparent substrate and protrudes from the surface of the transparent substrate, and the hole injection layer or the transparent conductive inorganic compound layer provided on the conductive pattern may be provided in contact with at least an upper surface of the metal wiring and the surface of the transparent substrate. [Effects of the Invention]

[0023] According to the present invention, it is possible to provide an organic EL element that can suppress the above-mentioned problems such as peeling in an organic EL element that includes an oxide such as a metal oxide having low acid resistance and that is made of metal wiring such as convex thin metal wires having a thickness greater than the average thickness of a conventional organic EL element, and further to provide an organic EL element that has improved brightness. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a top view of an organic EL element according to an embodiment. [Figure 2] Cross-sectional view (simplified) of an organic EL element taken along the line A-A' in Figure 1 [Figure 3] 1 is a top view of a metal grid transparent electrode according to an embodiment; [Figure 4] Mesh pattern (square, rectangle, diamond) of metal grid transparent electrode according to one embodiment [Figure 5] Honeycomb pattern of a metal grid transparent electrode according to one embodiment [Figure 6] Line and space pattern of a metal grid transparent electrode according to one embodiment [Figure 7]1 is a cross-sectional view of a conductive pattern of a metal grid transparent electrode according to one embodiment. [Figure 8] JVL characteristics of Example A1 (graph) [Figure 9] Appearance photograph of the organic EL element in Example A1 when the applied voltage was 4 V [Figure 10] Cross-sectional SEM image of the organic EL element of Example A8 [Figure 11] Simulation of spatial luminance distribution when applied voltage is 4V and comparison with optical microscope image of the emitting organic EL element of Example A1 [Figure 12] Graph of GTCE-brightness at different line widths [Figure 13] GTCE·ATCE-brightness graph for different line widths [Figure 14] Optical microscope image of the organic EL element of Example C1 emitting light when an applied voltage of 4 V is applied. DETAILED DESCRIPTION OF THE INVENTION

[0025] An embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail below, but the present invention is not limited to this and various modifications are possible without departing from the spirit of the present invention. The upper and lower limit values ​​of each numerical range in the present embodiment can be arbitrarily combined to form any numerical range. In the drawings, identical elements are given the same symbols and redundant explanations will be omitted. Furthermore, unless otherwise specified, positional relationships such as up, down, left, and right will be based on the positional relationships shown in the drawings. Furthermore, the dimensional ratios in the drawings are not limited to those shown. [Organic EL element]

[0026] The organic EL device 10 of this embodiment includes a metal grid transparent electrode 20, a cathode 60 facing the metal grid transparent electrode 20, and an organic functional layer 40 provided between the metal grid transparent electrode 20 and the cathode 60. The metal grid transparent electrode 20 has a transparent substrate 22 and an electrode portion formed of a conductive pattern 24P made of thin metal wires 24 (an example of "metal wiring") provided on the transparent substrate 22, the thin metal wires 24 containing a metal component M that provides conductivity and an oxide of the metal component M. The organic functional layer 40 includes a doped hole injection layer 42 and a hole transport layer 44 made of a low-molecular-weight organic material, and the doped hole injection layer 42 is disposed on the conductive pattern 24P. The film thickness t TCE (FIG. 2) is 50 nm or more and 250 nm or less, and the film thickness of the organic functional layer 40 on the metal thin wire 24 is t org-TCE (Figure 2), (t org-TCE -t TCE ), that is, the difference between the film thickness of the organic functional layer 40 and the film thickness of the thin metal wires 24 is 50 nm or more and 750 nm or less.

[0027] In this specification, "fine metal wires 24 provided on transparent substrate 22" refers not only to a configuration consisting of fine metal wires 24 provided on transparent substrate 22 in contact with the surface of transparent substrate 22, but also to a configuration consisting of fine metal wires 24 provided on transparent substrate 22 via another layer provided between transparent substrate 22 and fine metal wires 24 without contacting the surface of transparent substrate 22. For example, a transparent conductive inorganic compound layer may be provided between transparent substrate 22 and fine metal wires 24. Similarly, when one object is provided on another object, the two objects may not be in contact with each other.

[0028] In the organic EL device 10 of this embodiment, a doped hole injection layer 42 and a hole transport layer 44 made of a low-molecular-weight organic material are sequentially laminated on a conductive pattern of a metal grid transparent electrode 20. The low-molecular-weight organic materials used for the doped hole injection layer 42 and the hole transport layer 44 can be formed by vapor deposition. Therefore, even when copper is selected as the metal component M and a metal grid transparent electrode 20 is used that includes thin metal wires 24 containing copper and copper oxide, the thin metal wires 24 are not exposed to an acidic aqueous solution or the like during the manufacturing process of the organic EL device 10, thereby preventing problems such as damage to the thin metal wires 24 and peeling of the thin metal wires 24 from the transparent substrate 22. Note that the term "low-molecular-weight organic material" used herein refers to an organic material used in a low-molecular-weight organic EL device 10, which is broadly classified into low-molecular-weight organic EL devices 10 and polymer-molecular-weight organic EL devices 10 in the technical field to which the present invention pertains. Furthermore, low molecular weight organic materials are distinguished from the macromolecules and polymer molecules defined by the International Union of Pure and Applied Chemistry (IUPAC) Commission on Macromolecular Nomenclature, and are organic materials that do not fall into these categories.

[0029] Furthermore, the organic EL element 10 of this embodiment is characterized in that the doped hole injection layer 42 and the hole transport layer 44 are made thicker than those used in conventional small molecule organic EL elements 10, thereby adjusting the total thickness of the organic functional layer 40 to be thicker than the thickness of the thin metal wires 24. This increases the distance between the thin metal wires 24 and the opposing cathode 60, resulting in an organic EL element 10 that is free from electrical shorts and has a small leakage current.

[0030] In this embodiment, the thin metal wires 24 have a convex structure relative to the transparent substrate 22. TCEThe thickness of the thin metal wires 24 (FIG. 2) corresponds to the length in the thickness direction (normal direction to the surface of the transparent substrate 22) of the thin metal wires 24 in a cross section perpendicular to the extension direction of the thin metal wires 24, and specifically refers to the thickness (height of the convexity) from the interface of the thin metal wires 24 on the transparent substrate 22 side to the surface of the thin metal wires 24. When the thin metal wires 24 are provided on the surface of the transparent substrate 22 in contact with the surface of the transparent substrate 22, the thickness of the thin metal wires 24 corresponds to the distance between the surface of the transparent substrate 22 and the upper end surface of the thin metal wires 24 in a cross section perpendicular to the extension direction of the thin metal wires 24. When the thin metal wires 24 are provided on the surface of the transparent substrate 22 in contact with the surface of a transparent conductive inorganic compound layer that is provided in contact with the surface of the transparent substrate 22, the thickness of the thin metal wires 24 corresponds to the distance between the surface of the transparent conductive inorganic compound layer and the upper end surface of the thin metal wires 24 in a cross section perpendicular to the extension direction of the thin metal wires 24.

[0031] In this embodiment, t TCE is between 50nm and 250nm. TCE is preferably 60 nm or more and 200 nm or less, more preferably 65 nm or more and 180 nm or less, and even more preferably 70 nm or more and 165 nm or less.

[0032] t TCE When the thickness is 50 nm or more, the resistance of the metal grid transparent electrode 20 can be reduced, and the area of ​​the organic EL element 10 tends to be increased. In addition, an increase in electrical resistance due to oxidation or corrosion of the surface of the thin metal wires 24 tends to be sufficiently suppressed.

[0033] On the other hand, t TCE By making the thickness of the organic functional layer 40 250 nm or less, the convex thin metal wires 24 can be sufficiently covered within an adjustment range of the thickness of the organic functional layer 40 that does not cause a decrease in the brightness or power efficiency of the organic EL element 10 due to an increase in the thickness of the organic functional layer 40. In addition, high transparency tends to be exhibited over a wide viewing angle.

[0034] t TCEcan be measured by observing the cross section of the metal grid transparent electrode 20 or the organic EL element 10 with an electron microscope (SEM, TEM, STEM), or by observing the plane of the metal grid transparent electrode 20 with a confocal laser microscope or the like. TCE This can also be confirmed by measuring the film thickness profile of the metal grid transparent electrode 20 using a stylus-type thin film step gauge.

[0035] In this embodiment, the thickness of the organic functional layer 40 on the thin metal wires 24 is t org-TCE When (t org-TCE -t TCE ), that is, the difference in thickness between the organic functional layer 40 and the thin metal wires 24 is 50 nm or more and 750 nm or less. org-TCE -t TCE ) is preferably 60 nm or more and 500 nm or less, more preferably 70 nm or more and 400 nm or less, and even more preferably 80 nm or more and 300 nm or less.

[0036] (t org-TCE -t TCE ) is 50 nm or more, the organic functional layer 40 can sufficiently cover the convex metal thin wires 24, and a sufficient distance from the opposing cathode 60 can be secured, thereby suppressing electrical short circuits and sufficiently reducing leakage current.

[0037] On the other hand, (t org-TCE -t TCEBy setting the thickness of the organic functional layer 40 to 750 nm or less, the thickness of the organic functional layer 40 is not excessively thick relative to the thickness of the thin metal wires 24, thereby preventing a decrease in the brightness and power efficiency of the organic EL element 10 that would otherwise occur with an increase in the thickness of the organic functional layer 40. There are two reasons why an increase in the thickness of the organic functional layer 40 reduces the brightness and power efficiency of the organic EL element 10. First, the current density in the organic functional layer 40 decreases in inverse proportion to a power, such as the cube of the thickness of the organic functional layer 40, according to the space charge limited current (SCLC) equation, when a constant applied voltage is applied. Second, an increase in the thickness of the organic functional layer 40 reduces the visible light transmittance of each layer constituting the organic functional layer 40, making it difficult to extract light to the outside. Therefore, it is preferable to adjust the thickness of the organic functional layer 40 to an appropriate range.

[0038] t org-TCE is (t org-TCE -t TCE ) is not particularly limited as long as it can be adjusted to the above range, but is preferably 100 nm or more and 1000 nm or less, more preferably 120 nm or more and 700 nm or less, even more preferably 135 nm or more and 550 nm or less, and particularly preferably 150 nm or more and 500 nm or less. org-TCE When the thickness is 100 nm or more, even when a low-resistance metal grid transparent electrode 20 is used, the convex thin metal wires 24 can be sufficiently covered with the organic functional layer 40, and a sufficient distance from the opposing cathode 60 can be secured, which tends to suppress electrical short circuits and sufficiently reduce leakage current.

[0039] On the other hand, t org-TCE By making the thickness of the organic functional layer 40 1000 nm or less, it is possible to prevent a decrease in the brightness and power efficiency of the organic EL element 10 due to an increase in the thickness of the organic functional layer 40.

[0040] t org-TCEcan be obtained from the total thickness of each layer constituting the organic functional layer 40. For example, when each layer of the organic functional layer 40 is formed by a vapor deposition method, it can be obtained from the total thickness of each layer calculated from the vapor deposition rate (e.g., Å / sec: vapor deposition film thickness per unit time) and the vapor deposition time (sec). It can also be confirmed by observing the cross section of the organic EL element 10 with an electron microscope (SEM, TEM, STEM). For example, in the cross-sectional SEM image of the organic EL element 10 shown in FIG. 10, the thickness can be determined by measuring the thickness of a portion with low image brightness (dark) corresponding to the organic functional layer 40 between portions with high image brightness (bright) corresponding to the thin metal wires 24 and the cathode 60. org-TCE It can be confirmed that the thickness of the organic functional layer 40 is greater than that of the thin metal wires 24. In addition, EDX (energy dispersive X-ray analysis) is performed on the observation field of an electron microscope image of a cross section of the organic EL element 10 to map the EDX intensity of the K shell of the carbon atom C, and the region between the thin metal wires 24 and the cathode 60 where the EDX intensity of the carbon atom C is greater can be determined as the organic functional layer 40 and the film thickness can be measured. As shown in FIG. 10 , according to the manufacturing method of this embodiment, the organic functional layer 40 provided on the thin metal wires 24 has a first height from the surface of the transparent substrate 22, and the organic functional layer 40 provided on the transparent substrate 22 in the region between adjacent thin metal wires 24 has a second height from the surface of the transparent substrate 22 that is lower than the first height.

[0041] Furthermore, the examples of Patent Documents 1 and 2 disclose a metal grid transparent electrode 20 in which a transparent conductive layer made of PSDOT:PSS is formed by a wet film-forming method using inkjet technology on a metal conductive layer formed by electrolytically plating silver or the like on thin metal wires 24 with a line width of 5.8 μm to 50 μm formed by a printing method using silver nanoparticles. In response to this, the present inventors have adjusted the line width of the thin metal wires 24 containing a metal component M and an oxide of the metal component M to a fine range of 5 μm or less, or even 3 μm or less to make them invisible. It is believed that when attempting to wet-form a layer made of PEDOT:PSS on such fine thin metal wires 24, the acidic aqueous coating solution of PEDOT:PSS is likely to underetch the metal oxide component of the thin metal wires 24 near the interface with the transparent substrate 22, resulting in the problem of peeling of the thin metal wires 24 from the transparent substrate 22.

[0042] The organic EL element 10 of this embodiment uses a metal grid transparent electrode 20 as the anode. The organic functional layer 40 is a multilayer structure mainly made of an organic material, which is provided between the anode and the cathode 60 and includes at least a doped hole injection layer 42 and a hole transport layer 44. For the organic functional layer 40, the cathode 60, etc., conventionally known materials and configurations that are generally used in organic EL elements 10 can be applied.

[0043] The organic EL element 10 may have the following various configurations. (A) Anode / doped hole injection layer 42 / hole transport layer 44 / organic light-emitting layer 46 / cathode 60 (B) Anode / Doped Hole Injection Layer 42 / Hole Transport Layer 44 / Organic Light-Emitting Layer 46 / Electron Transport Layer 48 / Cathode 60 (C) Anode / Doped Hole Injection Layer 42 / Hole Transport Layer 44 / Organic Light-Emitting Layer 46 / Electron Injection Layer 50 / Cathode 60 (D) Anode / Doped Hole Injection Layer 42 / Hole Transport Layer 44 / Organic Light-Emitting Layer 46 / Electron Transport Layer 48 / Electron Injection Layer 50 / Cathode 60

[0044] The symbol " / " in the above (A) to (D) indicates that the layers on either side of the symbol " / " are stacked adjacent to each other. This also applies to the following explanations. The organic EL element 10 may have a configuration including two or more organic light-emitting layers 46.

[0045] The thickness of the organic functional layer 40 is t org-TCE In the case of the above configuration (A), corresponds to the sum of the film thickness of the doped hole injection layer 42, the film thickness of the hole transport layer 44, and the film thickness of the organic light-emitting layer 46.

[0046] In the case of the above configuration (B), t org-TCE corresponds to the sum of the thickness of the doped hole injection layer 42, the thickness of the hole transport layer 44, the thickness of the organic light emitting layer 46, and the thickness of the electron transport layer 48.

[0047] In the case of the above configuration (C), t org-TCEcorresponds to the sum of the thickness of the doped hole injection layer 42, the thickness of the hole transport layer 44, and the thickness of the organic light-emitting layer 46. As will be described later, the electron injection layer 50 is usually made of an alkali metal or the like, and in that case, it is not included in the organic functional layer 40.

[0048] In the case of the above configuration (D), t org-TCE corresponds to the sum of the thickness of the doped hole injection layer 42, the thickness of the hole transport layer 44, the thickness of the organic light-emitting layer 46, and the thickness of the electron transport layer 48. As will be described later, the electron injection layer 50 is usually made of an alkali metal or the like, and in that case, it is not included in the organic functional layer 40.

[0049] As will be described later, the organic EL element 10 may also include a transparent conductive inorganic compound layer. In this case, the transparent conductive inorganic compound layer is not included in the organic functional layer 40. org-TCE does not include the film thickness of the transparent conductive inorganic compound layer. [Metal grid transparent electrode 20]

[0050] The metal grid transparent electrode 20 of this embodiment has a transparent substrate 22 and an electrode portion made up of a conductive pattern 24P made up of thin metal wires 24 provided on the transparent substrate 22. [Transparent base material 22]

[0051] In this embodiment, a transparent substrate 22 is used. Here, "transparent" means that the visible light transmittance is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more. Here, the visible light transmittance can be measured in accordance with JIS K 7361-1:1997.

[0052] The transparent substrate 22 may be made of one material or may be made of a laminate of two or more materials. When the transparent substrate 22 is a multilayer structure made of two or more materials, the transparent substrate 22 may be made of a laminate of transparent organic or transparent inorganic substrates, which are examples of the core layer described below, or may be made of a combination of transparent organic or transparent inorganic substrates. The transparent substrate 22 may be a single layer or a multilayer structure, and a barrier layer, intermediate layer, or the like may be provided on the core layer as appropriate. Examples of the transparent substrate 22 include a core layer, a core layer / barrier layer, a core layer / barrier layer / intermediate layer, and a core layer / intermediate layer / barrier layer. A single layer may also function as both a barrier layer and an intermediate layer. (core layer)

[0053] The material constituting the core layer is not particularly limited, but is preferably one that contributes to improving the mechanical strength of the substrate. Examples of materials for such a core layer include, but are not limited to, transparent inorganic substrates such as quartz glass, alkali-free glass, borosilicate glass, soda-lime glass, and lead glass; and transparent organic substrates such as acrylic esters, methacrylic esters, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyarylate, polyvinyl chloride, polyethylene, polypropylene, polystyrene, nylon, aromatic polyamide, polyether ether ketone, polysulfone, polyethersulfone, polyimide, and polyetherimide. Among these, polyethylene terephthalate improves the productivity (cost reduction) of manufacturing the metal grid transparent electrode 20. Furthermore, polyimide improves the heat resistance of the metal grid transparent electrode 20. When using polyimide, it is more preferable to use so-called transparent polyimide, which has excellent visible light transmittance. Furthermore, by using polyethylene terephthalate, polyethylene naphthalate, or quartz glass or alkali-free glass, the adhesion between the transparent substrate 22 and the thin metal wires 24 tends to be further improved.

[0054] The thickness of the core layer is preferably 5 μm or more and 2 mm or less, and more preferably 10 μm or more and 1.5 mm or less. (middle class)

[0055] The intermediate layer can contribute to improving the adhesion between the transparent substrate 22 and the thin metal wires 24, or between the core layer and the barrier layer. Furthermore, in the manufacturing process of the metal grid transparent electrode 20 described below, when the metal components in the ink are sintered by a baking method such as plasma to form the electrode, the intermediate layer can prevent etching of the core layer or barrier layer in areas not covered with the thin metal wires 24 by the plasma.

[0056] The components contained in the intermediate layer are not particularly limited, but examples thereof include silicon compounds (e.g., (poly)silanes, (poly)silazanes, (poly)silthians, (poly)siloxanes, silicon, silicon carbide, silicon oxide, silicon nitride, silicon chloride, silicate, zeolite, silicide, etc.), aluminum compounds (e.g., aluminum oxide, etc.), magnesium compounds (e.g., magnesium fluoride), etc. Among these, silicon compounds are preferred, and siloxanes are more preferred. The silicon compounds are not particularly limited, but examples thereof include condensates of polyfunctional organosilanes, and polycondensates obtained by hydrolyzing polyfunctional organosilanes or oligomers thereof with polyvinyl acetate. The polyfunctional organosilane is not particularly limited, but examples thereof include bifunctional organosilanes such as dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diphenyldimethoxysilane, and diphenyldiethoxysilane; trifunctional organosilanes such as methyltrimethoxysilane, methyltriethoxysilane, and phenyltrimethoxysilane; and tetrafunctional organosilanes such as tetramethoxysilane and tetraethoxysilane.

[0057] The intermediate layer can be formed by applying a composition containing the components contained in the intermediate layer to the core layer or barrier layer and drying it. Alternatively, the intermediate layer may be formed by a vapor phase film formation method such as PVD or CVD. The composition for forming the intermediate layer may contain a dispersant, a surfactant, a binder, etc., as necessary.

[0058] The thickness of the intermediate layer is preferably 0.01 μm to 100 μm, more preferably 0.01 μm to 10 μm, and even more preferably 0.01 μm to 1 μm. When the thickness of the intermediate layer is within the above range, the adhesion is further improved, and the transparency and durability of the metal grid transparent electrode 20 tend to be further improved. (barrier layer)

[0059] The barrier layer has high blocking properties against moisture and oxygen, and contributes to suppressing deterioration of the characteristics of the organic EL element 10 due to the penetration of moisture and oxygen into the organic EL element 10. The gas barrier properties of the barrier layer are such that the water vapor permeability (25±0.5°C, relative humidity (90±2)%) measured by a method conforming to JIS K 7129-1992 is 1×10 -7 g / (m 2 24hr)~1×10 -3 g / (m 2 24 hours), and -7 g / (m 2 24hr)~1×10 -4 g / (m 2 24 hours), and 1×10 -7 g / (m 2 24hr)~1×10 -6 g / (m 2 It is more preferable that the water vapor transmission rate is in the range of 1×10 24 hr. When the water vapor transmission rate is in this range, the occurrence of dark spots, which are non-luminous areas, that occur in the organic EL element during long-term use can be suppressed, and the deterioration of the characteristics of the organic EL element during long-term use can be suppressed. Furthermore, it is preferable that the oxygen transmission rate measured by a method in accordance with JIS K 7126-1987 is in the range of 1×10 24 hr. -6 mL / m 2 24h atm~1×10-2 mL / m 2 ·24h·atm is preferred, and 1×10 -6 mL / m 2 24h atm~1×10 -3 mL / m 2 24h atm is more preferable, and 1×10 -6 mL / m 2 24h atm~1×10 -4 mL / m 2 ·24h·atm is even more preferable.

[0060] The barrier layer may have a conventionally known composition, structure, and formation method generally used in the organic EL device 10. The barrier layer may be a single layer, or may have a laminated structure of two or more layers. In the case of a laminated structure, the barrier layer may be a laminate of inorganic compound layers, organic compound layers, or inorganic polymer layers, as described below, or a laminate of a combination of inorganic compound layers, organic compound layers, or inorganic polymer layers. Among these, a structure in which inorganic compound layers and organic compound layers are alternately laminated multiple times is preferred in order to improve the fragility of the barrier layer.

[0061] The inorganic compound layer of the barrier layer is not particularly limited, but may be, for example, silicon oxide (SiO X(0<X≦2) ), silicon nitride (SiN X(0<X≦4 / 3) ), silicon oxynitride (SiO X N Y ), aluminum oxide (AlO X(0<X≦3 / 2)), aluminum nitride (AlN), etc. can be used. Examples of methods for forming the inorganic compound layer include vapor-phase film formation methods such as PVD (Physical Vapor Deposition) and CVD (Chemical Vapor Deposition). To form a dense inorganic compound layer with few pinholes and high gas barrier properties, the inorganic compound layer is preferably formed by sputtering, PECVD, or ALD (Atomic Layer Deposition). The film thickness of the inorganic compound layer is preferably 30 nm to 1000 nm, more preferably 50 nm to 500 nm, and even more preferably 100 nm to 200 nm. An inorganic compound layer with a film thickness of 30 nm or more provides excellent gas barrier properties. An inorganic compound layer with a film thickness of 1000 nm or less provides excellent visible light transmittance. Furthermore, the generation of cracks due to bending can be suppressed, and the increase in internal stress during film formation can be suppressed, preventing the generation of defects.

[0062] The organic compound layer of the barrier layer is not particularly limited, and examples thereof include thermosetting resins such as phenolic resin, thermosetting epoxy resin, thermosetting polyimide, melamine resin, urea resin, unsaturated polyester resin, alkyd resin, polyurethane, diallyl phthalate resin, and silicone resin, UV-curable resins such as urethane acrylate, acrylic resin acrylate, epoxy acrylate, silicone acrylate, and UV-curable epoxy resin, and commercially available coating agents. The organic compound layer may also have a structure in which particles of a hygroscopic compound are dispersed within the layer. Examples of hygroscopic compounds include metal oxides (e.g., sodium oxide, potassium oxide, calcium oxide, barium oxide, magnesium oxide, aluminum oxide, etc.), sulfates (e.g., sodium sulfate, calcium sulfate, magnesium sulfate, cobalt sulfate, etc.), metal halides (e.g., calcium chloride, magnesium chloride, cesium fluoride, tantalum fluoride, cerium bromide, magnesium bromide, barium iodide, magnesium iodide, etc.), and perchlorates (e.g., barium perchlorate, magnesium perchlorate, etc.). Among sulfates, metal halides, and perchlorates, anhydrous salts are preferably used. The organic compound layer can be formed, for example, by applying a coating solution of the above-mentioned resin, drying, and then curing by irradiating with heat or ultraviolet light. When the organic compound layer contains a hygroscopic material, the organic compound layer can be formed using a coating solution in which the hygroscopic material is dispersed. The film thickness of the organic compound layer is preferably 0.5 μm to 100 μm, more preferably 5 μm to 50 μm, and even more preferably 10 μm to 30 μm. When the thickness of the organic compound layer is 0.5 μm or more, the gas barrier property is excellent, and when the thickness of the organic compound layer is 100 μm or less, the visible light transmittance is excellent.

[0063] The inorganic polymer layer of the barrier layer is not particularly limited, but silicon-containing polymers such as polysilanes, polysilazanes, polysilthians, polysiloxanes, and polysiloxazanes can be used. Among these, polysiloxanes having Si-O bonds, polysilazanes having Si-N bonds, and polysiloxazanes containing both Si-O and Si-N bonds are preferred. The inorganic polymer layer can be formed, for example, by applying a coating liquid containing a polysilazane compound, drying it, and then oxidizing it by ultraviolet irradiation in a nitrogen atmosphere containing oxygen and water vapor. The thickness of the inorganic polymer layer is preferably 10 nm to 10 μm, more preferably 30 nm to 8 μm, and even more preferably 50 nm to 5 μm. A thickness of 10 nm or more of the organic compound layer provides excellent gas barrier properties. A thickness of 10 μm or less of the organic compound layer provides excellent visible light transmittance.

[0064] It is particularly preferable to use the same material and structure as the thin film encapsulation layer 70 (TFE: Thin Film Encapsulation) disclosed in Non-Patent Document 3 as the barrier layer. [Electrode part]

[0065] The electrode portion includes a conductive pattern 24P configured from thin metal wires 24 arranged on a transparent substrate 22. The thin metal wires 24 contain a metal component M and an oxide of the metal component M.

[0066] The metal component M is responsible for the conductivity of the thin metal wires 24. The mechanism by which the metal component M exerts its conductivity is not particularly limited, but is presumed to be similar to the free electron model of metals. The metal component M is not particularly limited, but examples include gold, silver, copper, and aluminum. Among these, copper, which is relatively inexpensive and highly conductive, is more preferable. The use of such a metal component M tends to further improve the conductivity of the metal grid transparent electrode 20. Note that a "metal grid" electrode includes an electrode in which multiple metal wires extending in different directions are provided, thereby providing multiple regions surrounded by the metal wires, with the intersections of the metal wires serving as vertices. Here, each metal wire may extend linearly or curvedly. The region surrounded by the metal wires is called an aperture, and the portion where the aperture is provided may be called an opening. As described below, the multiple metal wires may be periodically arranged at a predetermined pitch, or may be arranged randomly in all or part of the region without being regularly arranged.

[0067] As disclosed in Patent Document 3, by including an oxide of the metal component M in the thin metal wires 24, the refractive index of the thin metal wires 24 can be made closer to that of the transparent substrate 22. By making the refractive index of the thin metal wires 24 closer to that of the transparent substrate 22, reflection or scattering occurring at the refractive index interface between the thin metal wires 24 and the transparent substrate 22 is suppressed, and haze is reduced, thereby further improving transparency even when a conductive pattern with the same line width and aperture ratio is used. For example, if the metal component M is copper, the refractive index of the thin metal wires 24 composed entirely of copper is 0.60, and the refractive index of the thin metal wires 24 composed entirely of copper oxide is 2.71. Therefore, if the thin metal wires 24 are composed of copper and copper oxide, the refractive index can be adjusted between these values ​​depending on the composition ratio.

[0068] Furthermore, as also disclosed in Patent Document 3, by including an oxide of metal component M in the thin metal wires 24, the adhesion between the transparent substrate 22 and the thin metal wires 24 can be improved in terms of mechanical properties such as bending, flexure, and flexing.

[0069] Furthermore, by including an oxide of the metal component M in the thin metal wires 24, the interface resistance during hole injection from the metal component M into the doped hole injection layer 42 is reduced, contributing to a reduction in the drive voltage of the organic EL device 10 and an improvement in power efficiency. The HOMO of organic materials typically used in hole injection layers and hole transport layers 44 is approximately 5.0 eV to 5.5 eV. In contrast, the work function of copper, for example, is approximately 4.65 eV, creating an energy barrier of at least 0.35 eV at the interface between copper and the doped hole injection layer 42. This energy barrier increases the interface resistance during hole injection from the metal component M. In contrast, by including, for example, cuprous oxide (valence band: approximately 5.25 eV) or cupric oxide (valence band: approximately 5.3 eV) at the interface between copper and the doped hole injection layer 42, holes can be injected from copper into the doped hole injection layer 42 via the valence band of the copper oxide, thereby reducing the energy barrier and interfacial resistance. A literature article (Xubing Lu et al., Effect of air exposure on metal / organic interface in organic field-effect transistors, Appl. Phys. Lett., June 2011, Vol. 98, p. 243301) discloses that hole injection from copper to an organic semiconductor with a HOMO of 5.0 eV via copper oxide can reduce the interface resistance compared to hole injection directly from copper.

[0070] The oxide of the metal component M is not particularly limited, but since it is preferable to select copper as the metal component M for the reasons mentioned above, cuprous oxide, cupric oxide, copper hydroxide, etc. are preferred.

[0071] The uneven distribution and uniformity of the oxide of the metal component M (i.e., oxygen atoms O) within the cross section of the fine metal wires 24 are not particularly limited. The oxide of the metal component M may be distributed approximately uniformly within the cross section of the fine metal wires 24. For example, the oxide of the metal component M may be unevenly distributed at the interface of the fine metal wires 24 on the transparent substrate 22 side, or may be unevenly distributed on the surface side of the fine metal wires 24 (the side opposite the transparent substrate 22 side). Among these, from the two viewpoints of improving transparency by bringing the refractive index of the fine metal wires 24 closer to that of the transparent substrate 22 and further improving mechanical adhesion between the transparent substrate 22 and the fine metal wires 24, it is preferable that the oxide of the metal component M be unevenly distributed in large amounts on the transparent substrate 22 and gradually decrease from the transparent substrate 22 side toward the thickness direction of the fine metal wires 24. Furthermore, from the viewpoint of reducing the interfacial resistance during hole injection into the doped hole injection layer 42 disposed on the conductive pattern, the oxide of the metal component M is preferably present on the surface side of the fine metal wires 24.

[0072] The uneven distribution and uniformity of the metal component M in the thin metal wire 24 can be confirmed by the distribution of the atomic % ratio of oxygen atoms O to the metal component M by STEM-EDX analysis of the cross section of the thin metal wire 24.

[0073] In a STEM-EDX analysis of a cross section of the thin metal wire 24 (FIG. 7) perpendicular to the extending direction of the thin metal wire 24, a 0.10 t TCE ~0.90t TCE The atomic percentage ratio O / M of oxygen atoms O to metal components M in the thickness range up to 0.10 ~ 0.90 is preferably 0.01 or more and 1.00 or less, more preferably 0.02 or more and 0.80 or less, and further preferably 0.03 or more and 0.75 or less. 0.10 ~ 0.90 When the atomic percentage ratio O / M is 0.01 or more, the transparency is excellent for the reasons mentioned above, and the mechanical adhesion between the transparent substrate 22 and the thin metal wires 24 tends to be improved. Also, the energy barrier during hole injection tends to be reduced. On the other hand, when the atomic percentage ratio O / M is 0.01 or more, the transparency is excellent for the reasons mentioned above, and the mechanical adhesion between the transparent substrate 22 and the thin metal wires 24 tends to be improved. 0.10 ~ 0.90 When the ratio is 1.00 or less, the proportion of oxides of the metal component M decreases, and the resistance tends to be lowered.

[0074] 0.75t from the interface of the metal thin wire 24 on the transparent substrate 22 side TCE ~0.90t TCE Atomic percentage O / M in the thickness range up to 0.75 ~ 0.90 is an index showing the ratio of oxygen atoms O present in the surface region of the metal thin wire 24. 0.75 ~ 0.90 is preferably 0.25 or less, more preferably 0.22 or less, and further preferably 0.18 or less. 0.75 ~ 0.90 When the atomic percentage ratio O / M is 0.25 or less, the resistance tends to be lower. The minimum value of the atomic percentage ratio O / M of 0.75 to 0.90 is preferably more than 0 in order to reduce the energy barrier during hole injection.

[0075] In addition, the thickness of the transparent substrate 22 is 0.10 t from the interface of the metal thin wire 24 on the transparent substrate 22 side. TCE ~0.25t TCE Atomic percentage O / M in the thickness range up to 0.10 ~ 0.25 is an index showing the proportion of oxygen atoms O present in the region on the interface side of the thin metal wires 24 on the transparent substrate 22 side. 0.10 ~ 0.25 is preferably 0.05 or more, more preferably 0.06 or more, and further preferably 0.07 or more. 0.10 ~ 0.25 When the atomic percentage ratio O / M is 0.05 or more, the transparency is excellent and the mechanical adhesion between the transparent substrate 22 and the thin metal wires 24 tends to be improved. 0.10 ~ 0.25 is preferably 1.10 or less, more preferably 1.00 or less, and further preferably 0.95 or less. 0.10 ~ 0.25 When the ratio is 1.10 or less, the resistance tends to be lower.

[0076] Therefore, for example, the fine metal wire 24 may have a first atomic % ratio O / M (e.g., a value of 0.25 or less) at a first position at a first distance from the interface of the fine metal wire 24 on the transparent substrate 22 side, and may have a second atomic % ratio O / M (e.g., a value of 0.05 or more and 1.10 or less) greater than the first value at a second position closer to the interface of the fine metal wire 24 on the transparent substrate 22 side than the first distance. Here, the first distance is (t TCE / 2) greater than (e.g., 0.75t TCE ~0.90t TCE ) and the second distance is (t TCE / 2) (e.g., 0.10t TCE ~0.25t TCE ) The second value may be at least twice as large as the first value.

[0077] Atomic % ratio O / M 0.10 ~ 0.90 , atomic % ratio O / M 0.75 ~ 0.90 , and atomic % ratio O / M 0.10 ~ 0.25 can be determined by STEM-EDX analysis of a cross section of the thin metal wire 24 perpendicular to the extension direction of the thin metal wire 24. Specifically, the thin metal wire 24 is cut in a direction perpendicular to the extension direction of the thin metal wire 24, and a thin section in which the cross section of the thin metal wire 24 is exposed is obtained as a measurement sample. In this case, if necessary, the metal grid transparent electrode 20 may be embedded in a support such as an epoxy resin before forming the thin section. The method for forming the cross section of the thin metal wire 24 is not particularly limited as long as it is a method that can suppress damage to the cross section of the thin metal wire 24 due to the formation and processing of the cross section, but preferably, a processing method using an ion beam (for example, a broad ion beam (BIB) processing method or a focused ion beam (FIB) processing method), precision mechanical polishing, an ultramicrotome, or the like can be used.

[0078] Next, the measurement sample obtained as described above is observed with a scanning transmission electron microscope (STEM) to obtain a STEM image of the cross section of the metal thin wire 24. At the same time, elemental mapping of the cross section of the metal thin wire 24 is performed by energy dispersive X-ray analysis (EDX). Specifically, the EDX intensity of the K shell of the oxygen atom O and the EDX intensity of the K shell of the metal component M are measured for each location on the cross section. This operation is performed on at least the cross section of the metal thin wire 24 from the interface of the metal thin wire 24 on the transparent substrate 22 side to 0.10 t TCE ~0.90t TCE The integrated value of the K-shell EDX intensity of oxygen atom O and the integrated value of the K-shell EDX intensity of metal component M in this region are calculated, and the ratio of these integrated values ​​is the atomic % ratio O / M 0.10 ~ 0.90 Also, the atomic percentage ratio O / M 0.75 ~ 0.90 and atomic % ratio O / M 0.10 ~ 0.25 For the thickness of the target area, the ratio of the integrated values ​​is calculated using the same method.

[0079] In addition, t TCE can be the maximum thickness from the interface of the thin metal wire 24 on the transparent substrate 22 side to the surface of the thin metal wire 24 within the measurement field of the STEM image of the cross section of the thin metal wire 24. From the viewpoint of preventing oxidation and contamination of the cross section of the thin metal wire 24, it is preferable to perform the formation of the cross section of the thin metal wire 24 and the STEM-EDX analysis in an inert atmosphere such as argon or in a vacuum.

[0080] Atomic % ratio O / M 0.10 ~ 0.90 , atomic % ratio O / M 0.75 ~ 0.90 , atomic % ratio O / M 0.10 ~ 0.25 Although there are no particular limitations on the values ​​of these, their increase or decrease can be controlled by adjusting the firing conditions when forming the thin metal wires 24. For example, when firing a desired pattern formed using ink containing an oxide of the metal component M, the atomic percentage ratio O / M in the thin metal wires 24 can be adjusted by adjusting the degree of oxidation or reduction of the oxide of the metal component M through the firing conditions.

[0081] Furthermore, the thin metal wires 24 may contain a non-conductive component in addition to the metal component M that provides conductivity. The non-conductive component is not particularly limited, and examples thereof include oxides of the metal component M and organic compounds. More specifically, these non-conductive components are derived from components contained in the ink described below, and include oxides of the metal component M and organic compounds that remain in the thin metal wires 24 after firing.

[0082] The content of the metal component M in the thin metal wires 24 is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. There is no particular upper limit to the content of the metal component M, but it is preferably less than 100% by mass. The content of the non-conductive component in the thin metal wires 24 is preferably 50% by mass or less, more preferably 40% by mass or less, and even more preferably 30% by mass or less. There is no particular lower limit to the content of the non-conductive component, but it is more than 0% by mass. (Conductive pattern)

[0083] The conductive pattern 24P may be a regular or irregular pattern. Examples include mesh patterns 24P1 to 24P3 (FIG. 4) formed by a plurality of linearly extending thin metal wires 24 intersecting in a mesh pattern, a honeycomb pattern 24P4 (FIG. 5) in which thin metal wires 24 are provided in portions corresponding to the sides of each hexagon so that hexagonal openings are formed without gaps, and a line pattern 24P5 (FIG. 6) in which a plurality of substantially parallel thin metal wires 24 are formed. The conductive pattern 24P may also be an arbitrary combination of the mesh patterns 24P1 to 24P3, honeycomb pattern 24P4, and line pattern 24P5. Furthermore, the conductive pattern 24P may be formed so that polygonal openings other than rectangular and hexagonal are formed without gaps. For example, when the thin metal wires 24 defining polygonal openings simultaneously define adjacent polygonal openings, the plurality of polygonal openings are formed without gaps. The conductive pattern 24P may also be configured so that openings of different polygonal shapes are formed. The meshes of the mesh patterns 24P1 to 24P3 may be squares (FIG. 4A) or rectangles (FIG. 4B) as shown in FIG. 4, or may be diamonds (FIG. 4C). The honeycomb pattern 24P4 may be formed in a regular hexagonal shape with a constant line width as shown in FIG. 5, or may be formed so that the line width of the vertices is increased so that the vertices of each opening are rounded. The thin metal wires 24 forming the line pattern 24P5 may be straight as shown in FIG. 6, or curved. Furthermore, some or all of the thin metal wires 24 forming the mesh patterns 24P1 to 24P3 and the honeycomb pattern 24P4 may be curved. (Line width)

[0084] Wire width W of thin metal wire 24 TCE is the line width W when the thin metal wire 24 is projected onto the surface of the transparent substrate 22 from the side of the transparent substrate 22 on which the conductive pattern 24P is arranged. TCE As shown in FIG. 7, in the case of a thin metal wire 24 having a trapezoidal cross section with a long base on the interface side with the transparent substrate 22, the width of the surface of the conductive thin wire in contact with the transparent substrate 22 is the line width W TCEThis becomes:

[0085] W TCE is preferably 0.25 μm or more and 5.0 μm or less, more preferably 0.25 μm or more and 4.0 μm or less, even more preferably 0.25 μm or more and 3.0 μm or less, still more preferably 0.25 μm or more and 2.0 μm or less, and particularly preferably 0.25 μm or more and 1.0 μm or less. TCE When the width W of the metal grid transparent electrode 20 is 0.25 μm or more, the resistance of the metal grid transparent electrode 20 can be reduced, and the area of ​​the organic EL element 10 tends to be larger. In addition, an increase in electrical resistance due to oxidation or corrosion of the surface of the metal thin wires 24 can be sufficiently suppressed. On the other hand, the line width W of the metal thin wires 24 TCE When the width W of the thin metal wires 24 is 5.0 μm or less, the spatial luminance distribution in the openings of the conductive pattern becomes uniform, so that a high aperture ratio can be maintained even when the gap is made small, which tends to improve the luminance of the organic EL. TCE By adjusting the thickness to 3.0 μm or less, the opaque metal thin wires 24 can be made invisible to the human eye, and the appearance and design of the organic EL element 10 can be improved. (gap)

[0086] The gap G of the conductive pattern 24P in this specification TCE refers to the shortest (minimum) distance (interval) between adjacent thin metal wires 24 that extend in the same direction within the conductive pattern 24P and face each other in a direction substantially perpendicular to the extending direction (however, if the thin metal wires 24 extend in a curved shape, the gap G TCE corresponds to the minimum distance between two adjacent thin metal wires 24 at which the straight lines approximating the curve are in roughly the same direction at least within a predetermined region).

[0087] In FIG. 12, the horizontal axis represents the gap G of the conductive pattern 24P. TCE The vertical axis is the brightness value obtained by the simulation, and the simulation results are plotted against different line widths W TCE As shown in the figure, G TCEThe upper limit of G is preferably 50 μm or less, more preferably 40 μm or less, even more preferably 30 μm or less, even more preferably 20 μm or less, even more preferably 15 μm or less, and particularly preferably 12 μm or less. TCE / W TCE is preferably 1.0 or more, more preferably 1.5, even more preferably 2.0, even more preferably 2.5 or more, even more preferably 3.0 or more, and particularly preferably 3.5. TCE / W TCE When G is 1.0 or more, the aperture ratio can be improved, and the brightness of the organic EL tends to be improved. TCE By keeping the gap width at 50 μm or less, the spatial luminance distribution in the openings of the conductive pattern tends to be more uniform, which tends to further improve the luminance and power efficiency of the entire organic EL device 10. The inventors of the present application speculate that the reason why a smaller gap improves the luminance of the entire organic EL device 10 is as follows: Holes injected from the thin metal wires 24 by application of an external voltage diffuse in-plane into the openings of the conductive pattern via the doped hole injection layer 42. By reducing the gap and shortening the diffusion distance of holes from the thin metal wires 24 to the center of the openings, the voltage drop due to the surface resistance of the doped hole injection layer 42 associated with the in-plane diffusion of holes can be reduced. Uniformizing the voltage in the openings of the conductive pattern can uniformize the spatial luminance distribution. Because luminance is calculated by dividing the in-plane integrated value of the spatial luminance distribution by the integrated area, it is believed that uniforming the spatial luminance distribution can improve the luminance of the entire organic EL device 10. (Opening ratio)

[0088] Conductive pattern aperture ratio A TCE is preferably 35% or more and less than 100%, more preferably 40% or more and 99% or less, even more preferably 50% or more and 98% or less, even more preferably 55% or more and 97% or less, even more preferably 60% or more and 96% or less, and particularly preferably 62% or more and 95% or less. TCE Aperture ratio A is 35% or more, which tends to improve the brightness of the organic EL. TCEWhen the area ratio is less than 100%, the occupation rate of the thin metal wires 24 per unit area increases, which reduces the sheet resistance and tends to enable the area of ​​the organic EL element 10 to be increased.

[0089] The "aperture ratio" of the conductive pattern can be calculated using the following formula for the area on the transparent substrate 22 where the conductive pattern is formed.

[0090] Opening ratio=(1−area occupied by conductive pattern / area of ​​transparent substrate 22 in the region where the conductive pattern is formed)×100

[0091] For example, if the conductive pattern 24P is a mesh pattern 24P1 in which square openings are formed as shown in Figure 4(A), when the line width is 1 μm and the gap is 4 μm, the area occupied by the conductive pattern per unit area (the area occupied by the metal wiring) is 36%, and the area of ​​the openings through which the transparent substrate 22 is exposed is 64%, so the opening ratio is 64%.

[0092] In FIG. 12, the horizontal axis represents the gap G of the conductive pattern 24P. TCE and aperture ratio A TCE The vertical axis is the brightness value obtained by the simulation, and the simulation results are plotted against different line widths W TCE This is a graph showing the (G TCE A TCE ) is the diffusion length of holes in the in-plane direction in the opening of the conductive pattern (G TCE ) to achieve uniform spatial luminance distribution and aperture ratio (A TCE ) and the increase in the amount of light extracted to the outside due to the increase in the gap are shown as indicators of improving the brightness of the organic EL element 10. For example, if the gap is made smaller at the same line width, the diffusion distance of holes is reduced, and the spatial brightness distribution of the opening is made uniform, thereby improving the brightness. On the other hand, as the aperture ratio decreases, the shadowing effect of the opaque metal thin wires 24 increases, making it difficult to extract light to the outside. Therefore, the inventors of the present application have TCE A TCEThe inventors have focused on the fact that the brightness of the organic EL element 10 equipped with the metal grid transparent electrode 20 can be improved by adjusting (G TCE A TCE ) is preferably 0.6 μm·% or more and 30 μm·% or less, more preferably 1.0 μm·% or more and 20 μm·% or less, even more preferably 1.2 μm·% or more and 17 μm·% or less, even more preferably 1.5 μm·% or more and 15 μm·% or less, and particularly preferably 2.0 μm·% or more and 12.0 μm·% or less. (G TCE A TCE ) is 0.6 μm·% or more, the spatial luminance distribution in the opening can be made uniform while suppressing the decrease in luminance due to the light-shielding effect of the thin metal wires 24, thereby improving the luminance of the organic EL element 10. TCE A TCE ) is 30 μm·% or less, the brightness of the organic EL element 10 can be improved by increasing the aperture ratio while suppressing a decrease in brightness at the aperture. (Cross-sectional shape)

[0093] The cross-sectional shape of the fine metal wire 24 is not strictly defined because the surface of the fine metal wire 24 is not necessarily flat and often has an uneven surface, but examples include an approximately trapezoidal shape, an approximately semicircular shape, an approximately semi-elliptical shape, etc. The term "approximately trapezoidal shape" used here means that the parts corresponding to the legs of the trapezoid may be straight lines (sides) or curved lines, and if the parts corresponding to the legs of the trapezoid are curved lines, they may be convex outward or convex inward. Furthermore, the term "approximately trapezoidal shape" means that the parts corresponding to the upper base may be straight lines (sides) or have unevenness. The cross-sectional shape of such fine metal wire 24 has a wire width W TCE and film thickness t TCE The thickness t of the thin metal wire 24 can be defined as follows. TCE Based on this, the height from the interface between the transparent substrate 22 and the conductive thin wire is set to 0.50t TCE and 0.90t TCE (Figure 7) Also, the height is 0.50t. TCE The width of the metal wire 24 at 0.50 and height 0.90t TCEThe width of the metal wire 24 at 0.90 In this case, W 0.50 / W TCE is preferably 0.70 or more and less than 1.00, more preferably 0.75 or more and 0.99 or less, and even more preferably 0.80 or more and 0.95 or less. 0.90 / W 0.50 is preferably 0.50 or more and 0.95 or less, more preferably 0.55 or more and 0.90 or less, and even more preferably 0.60 or more and 0.85 or less. 0.50 / W TCE W 0.90 / W 0.50 That is, it is preferable that the thickness of the thin metal wire 24 on the transparent substrate 22 side is 0.50t or more. TCE Thickness at height from 0.90t TCE It is preferable that the width of the thin metal wires 24 gradually decrease toward a height position in the thickness direction. This reduces the edges in the cross section of the thin metal wires 24 and further improves the uniformity of the film thickness of the organic functional layer 40 attached to the thin metal wires 24, which tends to suppress electrical shorts with the cathode 60 and reduce the leakage current of the organic EL element 10.

[0094] As will be described later, the metal grid transparent electrode 20 of this embodiment can be formed by a printing method using ink, and the thin metal wires 24 formed by this method have the characteristic shape described above.

[0095] The line width of the thin metal wires 24 and the gap and aperture ratio of the conductive pattern 24P can be confirmed by examining the surface or cross section of the metal grid transparent electrode 20 with an electron microscope, laser microscope, optical microscope, or the like. Methods for adjusting the line width of the thin metal wires 24 and the gap of the conductive pattern 24P to within the desired range include adjusting the grooves of a plate used in the manufacturing method of the metal grid transparent electrode 20 described below, and adjusting the average particle size of metal particles in ink. (sheet resistance)

[0096] The sheet resistance R of the conductive pattern 24P of the metal grid transparent electrode 20 s_TCEis preferably 0.1 Ω / sq. or more and 100 Ω / sq. or less. The upper limit of the sheet resistance is more preferably 50 Ω / sq. or less, even more preferably 40 Ω / sq. or less, even more preferably 35 Ω / sq. or less, and particularly preferably 25 Ω / sq. or less. A sheet resistance of 100 Ω / sq. or less can suppress a decrease in brightness of the organic EL element 10 due to a voltage drop caused by the electrical resistance of the metal grid transparent electrode 20, and tends to enable the organic EL element 10 to be made larger in area. The sheet resistance can be reduced by adjusting the aperture ratio of the conductive pattern 24P, increasing the film thickness of the thin metal wires 24, increasing the content of the metal component M in the thin metal wires 24, selecting a metal component M with high conductivity, or the like.

[0097] The sheet resistance can be measured by a four-terminal method in accordance with JIS K 7194:1994 for the portion where the conductive pattern 24P is arranged. An example of a measuring device for the four-terminal method is "Loresta GP" (product name, manufactured by Mitsubishi Chemical Corporation). The sheet resistance can also be measured by a non-contact method using eddy current in accordance with ASTM F 673-02 for the portion where the conductive pattern 24P is arranged. (Visible light transmittance)

[0098] The visible light transmittance T of the area where the conductive pattern 24P of the metal grid transparent electrode 20 is arranged VLT is preferably 30% or more and 98% or less, more preferably 36% or more and 96% or less, even more preferably 45% or more and 94% or less, even more preferably 49% or more and 92% or less, even more preferably 54% or more and 91% or less, and particularly preferably 55% or more and 90% or less. Visible light transmittance tends to improve by increasing the aperture ratio of the conductive pattern 24P. Visible light transmittance can be calculated from the transmission spectrum of the region of the metal grid transparent electrode 20 where the conductive pattern 24P is arranged, in accordance with JIS R 3106:2019 or ISO 9050:2003. It can also be calculated by multiplying the visible light transmittance of the transparent substrate 22 by the aperture ratio of the conductive pattern 24P. [Transparent conductive inorganic compound layer]

[0099] In the metal grid transparent electrode 20 of this embodiment, a transparent conductive inorganic compound layer can be provided on the conductive pattern 24P. The transparent conductive inorganic compound layer can also be disposed between the transparent substrate 22 and the conductive pattern 24P. By providing a transparent conductive inorganic compound layer on the metal grid transparent electrode 20, holes can diffuse from the metal wiring through the transparent conductive inorganic compound layer into the openings in the conductive pattern 24P, thereby making the spatial luminance distribution of the openings more uniform. Note that, when a transparent conductive inorganic compound layer is provided on the conductive pattern 24P, the doped hole injection layer 42 is provided on the transparent conductive inorganic compound layer.

[0100] As described above, in order to avoid exposing the metal wiring to an acidic aqueous solution, the transparent conductive inorganic compound layer is preferably formed by a vapor phase film formation method such as PVD or CVD, and is particularly preferably formed by a sputtering method or a vacuum deposition method.

[0101] The material used for the transparent conductive inorganic compound layer is not particularly limited as long as it is an inorganic compound that has high transmittance in the visible light region and exhibits conductivity. Examples of suitable materials include In2O3-based materials such as ITO, SnO2-based materials such as ATO and FTO, ZnO-based materials such as AZO and GZO, (ZnO-In2O3)-based materials such as Zn2In2O5 and Zn3In2O2, and In4Sn3O 12 Examples include (In2O3-SnO2) systems such as Zn2SnO4 and ZnSnO3, and (ZnO-SnO2) systems such as Zn2SnO4 and ZnSnO3. Other known materials used for transparent conductive oxides can also be used. Among these, it is preferable to use ITO (indium tin oxide), which is the most widely used and has excellent transparency and conductivity.

[0102] The film thickness of the transparent conductive inorganic compound layer is preferably 10 nm to 1000 nm, more preferably 10 nm to 500 nm, even more preferably 10 nm to 300 nm, and particularly preferably 10 nm to 200 nm. A film thickness of 10 nm or more of the transparent conductive inorganic compound layer can reduce the sheet resistance of the transparent conductive inorganic compound layer, further promoting the diffusion of holes into the openings of the conductive pattern 24P through the transparent conductive inorganic compound layer, and tending to more uniform the spatial luminance distribution of the openings. On the other hand, a film thickness of 1000 nm or less of the transparent conductive inorganic compound layer tends to suppress a decrease in the luminance of the organic EL element 10 due to a decrease in the visible light transmittance of the transparent conductive inorganic compound layer. In particular, a film thickness of the transparent conductive inorganic compound in the range of 10 nm to 30 nm is particularly preferred because it increases the transmittance of the transparent conductive inorganic compound and improves the light-emitting characteristics of the organic EL element itself.

[0103] The upper limit of the sheet resistance of the transparent conductive inorganic compound layer is preferably 500 Ω / sq. or less, more preferably 200 Ω / sq. or less, even more preferably 100 Ω / sq. or less, and particularly preferably 50 Ω / sq. or less. Having a sheet resistance of 500 Ω / sq. or less of the transparent conductive inorganic compound layer promotes the diffusion of holes into the openings of the conductive pattern 24P via the transparent conductive inorganic compound layer, which tends to make the spatial luminance distribution of the openings more uniform. The lower limit of the sheet resistance of the transparent conductive inorganic compound layer is not particularly limited, and can be, for example, 0.1 Ω / sq.

[0104] The lower limit of the visible light transmittance of the transparent conductive inorganic compound layer is preferably 60% or more, more preferably 70% or more, even more preferably 80% or more, and particularly preferably 90% or more. When the visible light transmittance of the transparent conductive inorganic compound layer is 60% or more, the brightness of the organic EL element 10 tends to be improved. There is no particular limitation on the upper limit of the visible light transmittance of the transparent conductive inorganic compound layer, and it can be, for example, 100% or less. [Method for manufacturing the metal grid transparent electrode 20]

[0105] A method for manufacturing the metal grid transparent electrode 20 includes a pattern formation step of forming a pattern on the transparent substrate 22 using ink containing a metal component M, and a firing step of firing the ink to form a conductive pattern and, if necessary, a second conductive pattern 26P that will become a current collecting portion, as described below. [Pattern Forming Process]

[0106] The pattern formation process is a process of forming a pattern using an ink containing a metal component M. The pattern formation process is not particularly limited as long as it is a plate-based printing method using a plate having grooves of the desired conductive pattern. For example, the process may include the steps of coating the surface of a transfer medium with ink, bringing the ink-coated transfer medium surface into contact with the raised surface of a relief plate and pressing the surface together to transfer the ink from the transfer medium surface to the raised surface of the relief plate, and bringing the ink-remaining transfer medium surface into contact with the surface of a transparent substrate 22 and pressing the surface together to transfer the ink remaining on the transfer medium surface to the surface of the transparent substrate 22. If an intermediate layer or barrier layer is formed on the transparent substrate 22, the ink is transferred to the outermost surface on the side to be transferred. If a transparent conductive inorganic compound layer is formed on the transparent substrate 22, the ink is transferred onto the transparent conductive inorganic compound layer. (ink)

[0107] The ink used in the pattern formation process contains a metal component M and a solvent, and may also contain a surfactant, a dispersant, a reducing agent, etc. The metal component M may be contained in the ink as metal particles or as a metal complex.

[0108] The average primary particle size of the metal particles is preferably 100 nm or less, more preferably 50 nm or less, and even more preferably 30 nm or less. The lower limit of the average primary particle size of the metal particles is not particularly limited, but may be 1 nm or more. By making the average primary particle size of the metal particles 100 nm or less, the width of the resulting thin metal wires 24 can be made thinner. The term "average primary particle size" refers to the particle size of each individual metal particle (a so-called primary particle), and is distinct from the average secondary particle size, which is the particle size of an aggregate (a so-called secondary particle) formed by a plurality of metal particles.

[0109] The metal particles are not particularly limited, and examples thereof include metal oxides and metal compounds containing a metal component M such as copper oxide as a constituent atom, and core / shell particles in which the core is a metal component M such as copper and the shell is a metal oxide such as copper oxide that also contains a metal component M as a constituent atom. The form of the metal particles can be determined appropriately from the viewpoints of dispersibility and sinterability.

[0110] The content of metal particles in the ink is preferably 1% by mass or more and 40% by mass or less, more preferably 5% by mass or more and 35% by mass or less, even more preferably 5% by mass or more and 35% by mass or less, and even more preferably 10% by mass or more and 35% by mass or less, relative to the total mass of the ink composition.

[0111] The surfactant is not particularly limited, but examples thereof include fluorine-based surfactants. The use of such surfactants tends to improve the coatability of the ink on the transfer medium (blanket) and the smoothness of the coated ink, resulting in a more uniform coating film. It is preferable that the surfactant be capable of dispersing the metal component M and be configured so as not to leave any residue after baking.

[0112] The content of the surfactant in the ink is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.1% by mass or more and 5% by mass or less, and even more preferably 0.5% by mass or more and 2% by mass or less, relative to the total mass of the ink composition.

[0113] The dispersant is not particularly limited, but examples thereof include dispersants that form a non-covalent bond or interact with the surface of the metal component M, and dispersants that form a covalent bond to the surface of the metal component M. Examples of functional groups that form non-covalent bonds or interact with the surface of the metal component M include dispersants having a phosphate group. Use of such dispersants tends to further improve the dispersibility of the metal component M.

[0114] The content of the dispersant in the ink is preferably 0.1% by mass or more and 30% by mass or less, more preferably 1% by mass or more and 20% by mass or less, and even more preferably 2% by mass or more and 10% by mass or less, relative to the total mass of the ink composition.

[0115] Further examples of the solvent include alcohol-based solvents such as monoalcohols and polyhydric alcohols; alkyl ether-based solvents; hydrocarbon-based solvents; ketone-based solvents; and ester-based solvents. These may be used alone or in combination of two or more. For example, a monoalcohol having 10 or less carbon atoms may be used in combination with a polyhydric alcohol having 10 or less carbon atoms. The use of such a solvent tends to further improve the coating properties of the ink on the transfer medium (blanket), the transfer properties of the ink from the transfer medium to the relief printing plate, the transfer properties of the ink from the transfer medium to the transparent substrate 22, and the dispersibility of the metal component M. It is preferable that the solvent be capable of dispersing the metal component M and be configured so as to be less likely to remain after firing.

[0116] The content of the solvent in the ink is the remainder of the above-mentioned components such as the metal particles, surfactant, and dispersant, and is, for example, preferably 50% by mass or more and 99% by mass or less, more preferably 60% by mass or more and 90% by mass or less, and even more preferably 70% by mass or more and 80% by mass or less, relative to the total mass of the ink composition. [Firing process]

[0117] In the firing step, for example, the metal component M in the ink transferred to the surface of the transparent substrate 22 is sintered to form the conductive pattern 24P and, if necessary, the second conductive pattern 26P that serves as the current collector. The firing method is not particularly limited as long as it can fuse the metal component M to form a metal component sintered film. For example, firing may be performed in a firing furnace, or may be performed using plasma, a heating catalyst, ultraviolet light, vacuum ultraviolet light, an electron beam, infrared lamp annealing, flash lamp annealing, a laser, or the like. If the resulting sintered film is susceptible to oxidation, firing in a non-oxidizing atmosphere is preferable. Furthermore, if metal oxides or the like are difficult to reduce using only the reducing agent contained in the ink, firing in a reducing atmosphere is preferable.

[0118] A non-oxidizing atmosphere is an atmosphere that does not contain oxidizing gases such as oxygen, and includes inert atmospheres and reducing atmospheres. An inert atmosphere is, for example, an atmosphere filled with an inert gas such as argon, helium, neon, or nitrogen. A reducing atmosphere refers to an atmosphere in which reducing gases such as hydrogen and carbon monoxide are present. The ink coating film (dispersion coating film) may be fired by filling a firing furnace with these gases to form a closed system. Alternatively, the firing furnace may be configured as a flow system and the dispersion coating film may be fired while flowing these gases. When firing a dispersion coating film in a non-oxidizing atmosphere, it is preferable to first evacuate the firing furnace to remove oxygen from the furnace and then replace it with a non-oxidizing gas. Furthermore, firing may be performed in a pressurized or reduced pressure atmosphere.

[0119] The baking temperature is not particularly limited, but is preferably 20°C or higher and 400°C or lower, more preferably 50°C or higher and 300°C or lower, and even more preferably 80°C or higher and 200°C or lower. A baking temperature of 400°C or lower is preferable because it allows the use of substrates with low heat resistance. A baking temperature of 20°C or higher is also preferable because the formation of the metal component sintered film proceeds sufficiently and the conductivity tends to be good. The obtained metal component sintered film contains a conductive component derived from the metal component M, and may also contain non-conductive components depending on the components used in the ink and the baking temperature.

[0120] In order to promote fusion of the metal component M and obtain a metal component sintered film with higher conductivity, it is more preferable to use a plasma firing method. From the same viewpoint, the plasma output is preferably 0.5 kW or more, more preferably 0.6 kW or more, and even more preferably 0.7 kW or more. There is no particular upper limit to the plasma output, as long as it is within a range that does not damage the transparent substrate 22 or intermediate layer used. Furthermore, the lower limit of the firing time depends on the plasma output, but from the viewpoint of productivity, the upper limit is preferably 1000 seconds or less, more preferably 600 seconds or less. Note that, if necessary, plasma firing may be performed multiple times. [Current collecting part]

[0121] The organic EL element 10 of this embodiment can include a current collector disposed on the transparent substrate 22 and electrically connected to the conductive pattern 24P. The organic EL element 10 is an element that controls light emission by voltage and current applied from an external circuit. Therefore, the current collector is connected to a terminal from the external circuit and functions to transmit the voltage and current signals applied from the external circuit to the conductive pattern 24P. FIG. 3 is a schematic top view showing the positional relationship between the conductive pattern 24P disposed on the transparent substrate 22 and a second conductive pattern 26P that is electrically connected to the conductive pattern 24P and functions as a current collector. However, the specific shapes of the conductive pattern 24P and the second conductive pattern 26P are omitted from FIG. 3.

[0122] The current collecting portion is not particularly limited as long as it can be electrically connected to the conductive pattern 24P, and may be made of conventionally known materials and configurations that are generally used in the organic EL element 10. Examples of materials that can be used as the current collecting portion include metals such as gold, silver, copper, aluminum, and molybdenum, metal laminates such as molybdenum / aluminum / molybdenum, and metal alloys thereof.

[0123] The organic EL device 10 of this embodiment may also include a current collecting section (bus bar) having a second conductive pattern 26P disposed on the transparent substrate 22 and electrically connected to the conductive pattern 24P. The second conductive pattern 26P may be made of the same materials, structure, and design as the conductive pattern 24P of the metal grid transparent electrode 20. To simplify the manufacturing process, the second conductive pattern 26P is preferably formed simultaneously with the conductive pattern 24P using the above-described method for manufacturing the metal grid transparent electrode 20. To prevent a decrease in the uniformity of light emission of the organic EL device 10 due to a voltage drop at the current collecting section, the above-described metal, metal laminate, or metal alloy may be laminated on the second conductive pattern 26P by vacuum deposition, sputtering, or other methods. (Occupied area ratio)

[0124] The occupied area ratio S of the second conductive pattern 26P Bus is preferably 50% or more and less than 100%. Bus The lower limit of the occupied area ratio S of the second conductive pattern 26P is more preferably 60% or more, and further preferably 70% or more. Bus When the value is within the above range, the electrical connection with the external terminal is improved, the resistance of the current collecting portion can be reduced, and the voltage drop of the applied voltage tends to be suppressed.

[0125] The "occupancy area ratio" of the conductive pattern can be calculated using the following formula for the area on the transparent substrate 22 where the conductive pattern is formed.

[0126] Occupancy rate=(area occupied by conductive pattern / area of ​​transparent substrate 22 in the region where conductive pattern is formed)×100

[0127] For example, when the second conductive pattern 26P is a square mesh pattern as shown in FIG. 4A, if the line width is 2 μm and the gap is 2 μm, the area occupied by the second conductive pattern 26P per unit area (the area occupied by the metal wiring) is 75%, so the occupied area ratio S BusSimilarly, if the line width is 5 μm and the gap is 12 μm, the occupied area ratio S Bus is 50%. (line width, gap)

[0128] The line width W of the thin metal wires 24 constituting the second conductive pattern 26P Bus is preferably 0.25 μm or more and 10 μm or less, more preferably 0.5 μm or more and 8 μm or less, and even more preferably 1 μm or more and 5 μm or less. Bus When the gap G of the second conductive pattern 26P is within the above range, the connectivity with the external terminals is improved, the sheet resistance of the current collecting portion can be reduced, and the voltage drop of the applied voltage tends to be suppressed. Bus is the occupied area ratio S Bus The conductive pattern and W are Bus It can be set appropriately depending on the situation. [Organic functional layer 40] [Doped hole injection layer 42]

[0129] The organic EL element 10 of this embodiment has a doped hole injection layer 42 made of a low-molecular-weight organic material in the organic functional layer 40. The doped hole injection layer 42 is provided on the conductive pattern 24P of the metal grid transparent electrode 20. The doped hole injection layer 42 of this embodiment can be formed by vapor deposition, and is therefore suitable for use with a metal grid transparent electrode 20 that includes thin metal wires 24 containing an oxide of a metal component M, such as copper oxide, which has low acid resistance. Furthermore, the doped hole injection layer 42 has the functions of suppressing electrical shorts and reducing leakage current in the organic EL element 10 due to an increased thickness, diffusing holes injected from the thin metal wires 24 into the openings in the conductive pattern 24P, and injecting holes into the hole transport layer 44.

[0130] As shown in the enlarged view of region A in FIG. 2 , when the dope hole injection layer 42 is provided on the conductive pattern 24P in contact with the upper surfaces of the fine metal wires 24, the dope hole injection layer 42 approaches the interface of the fine metal wires 24 on the transparent substrate 22 side in the region between adjacent fine metal wires 24 (the surface of the transparent substrate 22, or, if a conductive inorganic compound layer is provided on the surface of the transparent substrate 22 and the fine metal wires 24 are provided on the conductive inorganic compound layer, the surface of the conductive inorganic compound layer) and comes into contact with the surface including the interface of the fine metal wires 24 on the transparent substrate 22 side. This makes it possible to coat the fine metal wires 24. Furthermore, when the conductive inorganic compound layer is provided on the conductive pattern 24P in contact with the upper surfaces of the fine metal wires 24, the conductive inorganic compound layer approaches the surface including the interface of the fine metal wires 24 on the transparent substrate 22 side in the region between adjacent fine metal wires 24 and comes into contact with the surface including the interface of the fine metal wires 24 on the transparent substrate 22 side.

[0131] The doped hole injection layer 42 is made of at least one low molecular weight host material and at least one low molecular weight dopant, and may be made of conventionally known materials and structures that are generally used in the organic EL device 10 . (Low molecular weight host material)

[0132] From the viewpoint of reducing the energy barrier in injecting holes into the hole transport layer 44, the low molecular weight host material is preferably a material used in the hole transport layer 44 or a material having a HOMO at a level close to that of the hole transport layer 44. The low molecular weight host material is not particularly limited, and examples thereof include (1) BF-DPB (N,N'-[(Diphenyl-N,N'-bis)9,9,-dimethyl-fluoren-2-yl]-benzidine), (2) MeO-TPD (N,N,N',N'-tetrakis(4-methoxyphenyl)-benzidine), (3) Spiro-TTB (2,2',7,7'-tetrakis(N,N'-di-p-methylphenylamino)-9,9'-spirobifluorene), (4) NPB (N,N'-di(naphtalene-1-yl)-N,N'-diphenylbenzidine), and (5) PV-TPD (N,N'-di(4-(2,2-diphenyl-ethen-1-yl)-phenyl)-N,N'-di(4-methylphenylphenyl) benzidine), (6) ZnPc (zinc-phthalocyanine), (7) TDATA, (8) m-MTDATA, (9) TPD, (10) CuPc, (11) HAT, (12) F 16CuPc, (13)1-TNATA(4,4',4''-Tris(N-(1-naphthyl)- (14)2-TNATA(4,4',4''-Tris[2-naphthyl(phenyl)amino]triphenylamine), (15)NPNPB(N,N'-d iphenyl-N,N'-di-[4-(N,N-diphenyl-amino)phenyl]benzidine), (16)DNTPD(N1,N1'-(Biphenyl-4,4'-diyl)bis(N1-phenyl-N4,N4 -di-m-tolylbenzene-1,4-diamine), (17) HAT-CN (1,4,5,8,9,11-Hexaazatriphenylenehexacarbonitrile), (18) PPDN (Pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile). (Note that the configuration and materials of organic EL devices including each organic functional layer can be described, for example, in Caroline Murawski et al., Alternative p-doped hole transport material for low operating voltage and high efficiency organic light-emitting diodes, Applied Physics Letters, September 2014, Vol. 105, P. 113303, S. Olthof et al., Journal of Applied Physics, Photoelectron spectroscopy study of systematically varied doping concentrations in an organic semiconductor layer using a molecular p-dopant, October 2009, Vol. 106, P. 103711, M Pfeiffer et al.This will be understood by those skilled in the art from the following descriptions: "Doped organic semiconductors: Physics and application in light emitting diodes," Organic Electronics, September 2003, Vol. 4, pp. 89-103; "Organic EL displays," by Shizuo Tokito, August 2004, Ohmsha, pp. 101-120, 114-119, 217-219, 224-269. Furthermore, the structure and materials of organic EL elements are described on the Internet as follows, and therefore can be understood by a person skilled in the art (the following lists examples of materials, etc., without giving specific examples of literature names, etc.). "Hole Injection Layer (HIL) Materials", [online], Shine Materials Technology Co., Ltd., [Retrieved September 6, 2021], Internet <URL: https: / / www.shinematerials.com / goods1-cat2-lang1.html> , "Hole Transport Layer (HTL) Materials", [online], Shine Materials Technology Co., Ltd., [Retrieved September 6, 2021], Internet <URL: https: / / www.shinematerials.com / goods1-cat15-lang1.html> , "Fluorescent Host Materials", [online], Shine Materials Technology Co., Ltd., [Retrieved September 6, 2021], Internet <URL: https: / / www.shinematerials.com / goods1-cat3-lang1.html> , "Phosphorescent Host Materials", [online], Shine Materials Technology Co., Ltd., [Retrieved September 6, 2021], Internet <URL: https: / / www.shinematerials.com / goods1-cat4-lang1.html> , "Hole Blocking / Electron Transporting Layer Materials", [online], Shine Materials Technology Co., Ltd., [Retrieved September 6, 2021], Internet <URL: https: / / www.shinematerials.com / goods1-cat16-lang1.html> , "Blue Dopant Materials", [online], Shine Materials Technology Co., Ltd., [Retrieved September 6, 2021], Internet <URL: https: / / www.shinematerials.com / goods1-cat17-lang1.html> , "Green Dopant Materials", [online], Shine Materials Technology Co., Ltd., [Retrieved September 6, 2021], Internet <URL: https: / / www.shinematerials.com / goods1-cat18-lang1.html> , "Red Dopant Materials", [online], Shine Materials Technology Co., Ltd., [Retrieved September 6, 2021], Internet <URL: https: / / www.shinematerials.com / goods1-cat19-lang1.html> (Low molecular dopant)

[0133] The low molecular weight dopant is not particularly limited as long as it is a material that imparts electrical conductivity to the doped hole injection layer 42 and improves hole diffusivity within the layer. For example, (1) F6-TCNNQ (p-dopnant) (2,2'-(perfluoronaphthalene-2,6-diylidene)dimalononitrile), (2) F4-TCNQ (2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane), (3) F2-TCNQ (3,6-difluoro-2,5,7,7,8,8-hexacyanoquinodimethane), (4) TCNQ (tetracynoquinodimethane), (5) NDP-2 (Novaled), (6) NDP-9 (Novaled), (7) ortho-chloranil, (8) DDQ (dicyano-dichloroquinone), (9) TPT9, (10) BSB-Cz, etc. (references, etc. are the same as above).

[0134] Thus, the doped hole injection layer 42 may comprise, for example, BF-DPB doped with F6-TCNNQ. (dopant density)

[0135] The dopant density N p The "vol %" refers to the volume (vol %) of the low molecular weight dopant contained in the doped hole injection layer 42 relative to the total volume of the doped hole injection layer 42. By increasing or decreasing the dopant density, the electrical conductivity (and sheet resistance) and the absorption coefficient in the visible light region (and visible light transmittance) of the doped hole injection layer 42 can be adjusted within preferred ranges. p is preferably 3 vol% or more and 18 vol% or less, more preferably 4 vol% or more and 15 vol% or less, and even more preferably 5 vol% or more and 10 vol% or less. p When the content of N is 3 vol % or more, the electrical conductivity of the doped hole injection layer 42 tends to be improved. p By making the content 18 vol % or less, absorption of visible light by the dopant is suppressed, and the visible light transmittance tends to improve.

[0136] N p can be controlled by adjusting the evaporation rate (e.g., Å / sec: evaporated film thickness per unit time) and evaporation time (sec) of each material in the co-evaporation process of the low-molecular-weight host material and the low-molecular-weight dopant. For example, based on the calibration curves of the evaporation rates of the low-molecular-weight host material and the low-molecular-weight dopant obtained in advance, the evaporation rate of the low-molecular-weight host material can be adjusted to 0.9 × α (Å / sec) and the evaporation rate of the low-molecular-weight dopant to 0.1 × α (Å / sec), thereby achieving N p can be set to 10 vol %. Note that α can be any value. (film thickness)

[0137] The thickness t of the doped hole injection layer 42 HIL is preferably 30 nm or more and 200 nm or less, more preferably 40 nm or more and 150 nm or less, and even more preferably 50 nm or more and 100 nm or less. HIL By making the thickness t 30 nm or more, it is possible to suppress electrical short circuits caused by thickening of the organic functional layer 40 and to reduce leakage current. In addition, since the sheet resistance of the doped hole injection layer 42 can be reduced, holes injected from the thin metal wires 24 can be more easily diffused into the openings of the conductive pattern 24P via the doped hole injection layer 42. This tends to make the spatial luminance distribution at the openings uniform. On the other hand, HIL When the thickness is 200 nm or less, the visible light transmittance of the doped hole injection layer 42 tends to be improved, which makes it easier to extract light emitted from the organic light-emitting layer 46 to the outside. In addition, it is possible to suppress a decrease in current density that occurs when the organic functional layer 40 is made thicker.

[0138] t HIL can be controlled by adjusting the evaporation rate and evaporation time of each material in the co-evaporation process of the low molecular weight host material and the low molecular weight dopant. HIL A value calculated from the deposition process conditions can be used as the value. (electrical conductivity)

[0139] Electrical conductivity σ of the doped hole injection layer 42 HIL The lower limit of is preferably 5 × 10 -5 S / cm or more, preferably 7×10 -5 S / cm or more, more preferably 8×10 -5 S / cm or more. HIL increases with increasing dopant density, but tends to saturate above a certain dopant density (e.g., 10 vol%). The electrical conductivity of 4,4',4''-tris[3-methylphenyl(phenyl) amino]triphenylamine (m-MTDATA), a typical example of a hole injection layer made from a low-molecular-weight organic material, is approximately 10 -10 The doped hole injection layer 42 of this embodiment has an electrical conductivity that is five orders of magnitude higher than that of a typical hole injection layer made of a conventional low molecular weight organic material, due to the addition of a low molecular weight dopant. HIL is 5 x 10 -5 By setting the resistivity at σ / cm or more, the sheet resistance of the doped hole injection layer 42 can be reduced, and holes injected from the thin metal wires 24 can be more easily diffused into the openings of the conductive pattern 24P via the doped hole injection layer 42. This tends to make the spatial luminance distribution at the openings more uniform. HIL The upper limit of is not particularly limited, but is, for example, 3.0 × 10 -4 This can prevent a decrease in the visible light transmittance of the doped hole injection layer 42 due to an increase in the dopant density. σ HIL is the sheet resistance measured for the thin film of the doped hole injection layer 42 by a four-terminal method in accordance with JIS K 7194:1994 or a non-contact method using eddy current in accordance with ASTM F 673-02, and the thickness t HIL It can be calculated from σ HIL can also be measured by the following method. First, a measurement sample is prepared by depositing the doped hole injection layer 42 on a comb-shaped electrode formed on a glass substrate. The electrical resistance R of the measurement sample at both ends of the comb-shaped electrode is measured. Then, the film thickness t of the doped hole injection layer 42 is measured. HIL, the channel length of the interdigital electrode L CH and the total channel width W CH Using the following formula, σ HIL (S / cm) can be calculated.

[0140] σ HIL =L CH / (R×t HIL ×W CH ) (sheet resistance)

[0141] The sheet resistance of the doped hole injection layer 42 can be calculated from the electrical conductivity and film thickness of the doped hole injection layer 42. The upper limit of the sheet resistance of the doped hole injection layer 42 is preferably 6.5×10 9 Ω / sq. or less, preferably 4.5×10 9 Ω / sq. or less, more preferably 3.0×10 9 Ω / sq. or less, particularly preferably 2.5×10 9 The sheet resistance of the doped hole injection layer 42 is 6.5×10 9 When the sheet resistance is Ω / sq. or less, holes injected from the thin metal wires 24 are easily diffused into the openings of the conductive pattern 24P via the doped hole injection layer 42, which tends to make the spatial luminance distribution at the openings uniform. The lower limit of the sheet resistance of the doped hole injection layer 42 is not particularly limited, but is preferably 1.5×10 8 This can suppress a decrease in the visible light transmittance of the doped hole injection layer 42 due to an increase in the film thickness or dopant density of the doped hole injection layer 42, and tends to make it easier to extract light emitted from the organic light-emitting layer 46 to the outside. (Visible light transmittance)

[0142] The visible light transmittance of the doped hole injection layer 42 tends to increase by decreasing the dopant density or the film thickness of the doped hole injection layer 42. The visible light transmittance of the doped hole injection layer 42 is preferably 80% or more and 100% or less, more preferably 82% or more and 97% or less, and even more preferably 84% or more and 95% or less. When the visible light transmittance of the doped hole injection layer 42 is 80% or more, it tends to be easier to extract light emitted from the organic light-emitting layer 46 to the outside.

[0143] The visible light transmittance of the doped hole injection layer 42 can be confirmed by the following method. A measurement sample is prepared by depositing the doped hole injection layer 42 on a glass substrate. Using this measurement sample and the glass substrate as a reference sample, UV-vis spectroscopy is performed to measure the optical absorption spectrum of the doped hole injection layer 42, eliminating the influence of the glass substrate. The transmission spectrum is calculated from the obtained optical absorption spectrum. The visible light transmittance can be calculated from the transmission spectrum of the doped hole injection layer 42 in accordance with JIS R 3106:2019 or ISO 9050:2003. [Hole transport layer 44]

[0144] The organic EL device 10 of this embodiment has a hole transport layer 44 made of a low-molecular-weight organic material in the organic functional layer 40. The hole transport layer 44 is provided on the doped hole injection layer 42 by vapor deposition. The hole transport layer 44 of this embodiment serves to prevent electrical shorts and reduce leakage current in the organic EL device 10 due to increased thickness, and to transport holes injected from the doped hole injection layer 42 to the organic light-emitting layer 46, etc. However, the hole transport layer 44 and the doped hole injection layer 42 may be made of the same material.

[0145] From the viewpoint of reducing the energy barrier for hole injection from the doped hole injection layer 42, the hole transport layer 44 is preferably formed of a material used as the low-molecular-weight host material for the doped hole injection layer 42, or a material having a HOMO level similar to that of the low-molecular-weight host material for the doped hole injection layer 42. Similarly, from the viewpoint of reducing the energy barrier for hole injection from the hole transport layer 44 to the organic light-emitting layer 46, the hole transport layer 44 is preferably formed of a material having a HOMO level similar to that of the organic light-emitting layer 46. From this viewpoint, the hole transport layer 44 may be formed of a single material, or may be formed by laminating two or more materials so that the HOMO of the hole transport layer 44 changes gradually from a level close to that of the doped hole injection layer 42 to a level close to that of the organic light-emitting layer 46. The material for the hole transport layer 44 is not particularly limited as long as it is a low-molecular-weight organic material, and conventionally known materials commonly used in organic EL devices 10 can be used.In addition to the materials described above for the doped hole injection layer 42, the hole transport layer 44 may be made of, for example, (1) Spiro-TAD (2,2',7,7'-Tetrakis(N,N-diphenylamino)-9,9'-spirobifluorene), (2) VNPB (N4,N4'-Di(naphthalen-1-yl)-N4,N4'-bis(4-vinylphenyl)biphenyl-4,4'-diamine), (3) Tris-PCz (9-Phenyl-3,6-bis(9-phenyl-9Hcarbazol-3-yl)-9H-carbazole), (4) TAPC (1,1-Bis[(di-4-tolylamino)phenyl]cyclohexane), (5) BF-DPB (N4,N4'-Bis (9,9-dimethyl-9H-fluoren-2-yl)-N4,N4'-diphenylbiphenyl-4,4'-diamine), (6) α-NPD (N,N'-Di-1-naphthyl-N,N'-diphenylbenzidine), (7) (DTP)DPPD, (8) HTM1, (9) TPTE1, (10) TCTA (tris(4-carbazoyl-9-ylphenyl)amine), (11) NTPA, (12) TFLFL, (13) TPTR, (14) TPTE, (15) TPPE, etc. (references, etc. are the same as above).

[0146] The thickness t of the hole transport layer 44 HTL is preferably 30 nm or more and 200 nm or less, more preferably 50 nm or more and 180 nm or less, even more preferably 80 nm or more and 170 nm or less, and particularly preferably 100 nm or more and 160 nm or less. HTL is the total thickness of the hole transport layer 44.

[0147] t HTL can be controlled by adjusting the evaporation rate and evaporation time of the material used for the hole transport layer 44 in the evaporation process. HTL A value calculated from the deposition process conditions can be used for the value. [Organic light-emitting layer 46]

[0148] The organic light-emitting layer 46 can be made of a conventionally known material that is generally used in the organic EL device 10. Examples of host materials used in the organic light-emitting layer 46 for fluorescent emission by radiative transition from an excited singlet state include (1) Alq3 (Tris(8-quinolinolato)aluminum (purified by sublimation)), (2) TBADN (2-tert-Butyl-9,10-di(naphth-2-yl)anthracene), (3) TPB3 (1,3,5-Tri(pyren-1-yl)benzene), (4) ADN (9,10-Bis(2-naphthyl)anthracene), (5) MADN (2-methyl-9,10-bis(naphthalen-2-yl)anthracene), (6) Alq, (7) Almq, (8) Almq, (9) Almq, (10) Almq, (11) Almq, (12) Almq, (13) Almq, (14) Almq, (15) Almq, (16) Almq, (17) Almq, (18) Almq, (19) Almq, (20) Almq, (21) Almq, (22) Almq, (23) Almq, (24) Almq, (25) Almq, (26) Almq, (27) Almq, (28) Almq, (29) Almq, (30) Almq, (31) Almq, (32) Almq, (33) Almq, (34) Almq, (35) Almq, (36) Almq, (37) Almq, (38) Almq, (39) Almq, (40) Almq, (41) Almq, (42) Almq, (43) Almq, (44) Al Examples of suitable materials include 8) Mgq, (9) BeBq2, (10) ZnPBO, (11) ZnPBT, (12) Be(5Fla)2, (13) BpVBi, (14) Eu complexes, (15) APD, (16) BSB, (17) BAlq (Bis(8-hydroxy-2-methylquinoline)-(4-phenylphenoxy)aluminum), (18) azomethine metal complexes, (19) distyrylbenzene derivatives, (20) DTVBi derivatives, and (21) DSB derivatives. The electron transport layer 48 and the organic light-emitting layer 46 may both be made of Alq3 (see above for references, etc.).

[0149] Furthermore, the organic light-emitting layer 46 may contain, as a guest material, perylene, DPT, PMDFB, quinacridone, rubrene, BTX, ABTX, DCM, DCJT, DCJTB, DCJMTB, TDPF, PtOEP, Btp2Ir(acac), coumarin derivatives (C540), distyryl compounds (BCzVBi), ADN, TBP, FIrpic, FIr6, or europium complexes (Eu(TTA)3phen) (same as above for cited references, etc.).

[0150] For example, it is known that the organic light-emitting layer 46 can achieve efficient blue emission by combining ADN, which has an anthracene skeleton, with the perylene derivative TBP. The organic light-emitting layer 46 may achieve efficient green emission by doping, for example, an anthracene dimer as a host material with 1% C545T as a guest material. Alternatively, the organic light-emitting layer 46 may achieve red emission by doping Alq3 as a host material with DCM1 or DCM2 as a guest material.

[0151] Furthermore, the organic light-emitting layer 46 may include a phosphorescent material for emitting phosphorescence due to radiative transition from an excited triplet state as well as fluorescence due to radiative transition from an excited singlet state.Examples of the materials include: (1) CBP (4,4’-Bis(N-carbazolyl)-1,1’-biphenyl), (2) TCTA, (3) UGH-2 (1,4-Bis(triphenylsilyl)benzene), (4) 26DCzPPy (2,6-bis(3-(carbazol-9-yl)phenyl)pyridine), (5) DPDT (2,8-Bis(diphenyl-phosphoryl)-dibenzo[b,d]thiophene), (6) DPEPO (Bis[2-(diphenylphosphino)phenyl]ether oxide), (7) mCPSOB (9-(3-(9H-Carbazol-9-yl)-5-(phenylsulfonyl)phenyl)-9H-carbazole), (8) DCzDCN (5-(4,6-Diphenyl-1,3,5-triazin-2-yl)benzene-1,3-dinitrile), (9) Spiro-2CBP (2,7-Bis(carbazol-9-yl)-9,9-spirobifluorene), (10) mCP (1,3-Bis(N-carbazolyl)benzene), (11) TCP (1,3,5-tris(carbazol-9-yl)benzene), (12) CzSi (1,3,5-tris(carbazol-9-yl)benzene), (13) BCBP (2,2’-bis(4-(carbazol-9-yl)phenyl)-biphenyl), (14) BCPO (Bis-4-(N-carbazolyl)phenyl)phenylphosphine oxide), (15) DCzDBT (2,8-Di(9-carbazolyl)dibenzothiophene), (16) mCBP (3,3-Di(9H-carbazol-9-yl)biphenyl), (17) CPCB (3-(3-(9H-Carbazol-9-yl)phenyl)-9-(3-(3-(3-(9H-carbazol-9-yl)phenyl)-9Hcarbazo-9-yl)phenyl)-9H-carbazole), (18) Spiro-CBP (2,2’,7,7’-Tetrakis(carbazol-9-yl)-9,9-spirobifluoren).Further examples include Btp2Ir(acac), iridium complex Ir(ppy)3, carbazole derivative CBP, Firpic, Fir6, Ir(thpy)3, Ir(t5m-thpy)3, Ir(t-5CF3-py)3, Ir(t-5t-py)3, Ir(mt-5mt-py)3, Ir(btpy)3, Ir(tflpy)3, Ir(piq)3, Ir(tiq)3, Ir(fliq)3, ppy, tpy, bzq, thp, оp, bo, bt, bon, αbsn, btp, ppo, C6, pq, β-bsn, ppz, Ir(Fppy)3, Ir(Fppy)2(acac), and Ir(ppy)2(acac) (same as above for cited references, etc.).

[0152] In addition to the fluorescent light-emitting materials, mainly organic low-molecular-weight compounds, and phosphorescent light-emitting materials such as platinum and iridium complexes, rare earth complexes can also be used for the organic light-emitting layer 46. Rare earth complexes are composed of rare earth ions (elements with atomic numbers 58 to 71, such as lanthanum (La), scandium (Sc), and yttrium (Y)) and organic ligands. Specifically, the organic light-emitting layer 46 may contain a Tb(III) complex, such as Tb(acac)3, or an Eu(III) complex. For example, the organic light-emitting layer 46 may be composed of poly(methylphenylsilane) (PMPS) doped with an Eu(III) complex. Alternatively, the organic light-emitting layer 46 may be composed of CBP doped with Eu(dbm)3(Tmphen), Eu(dbm)3(phen), or Tb(dbm)3(phen). The organic light-emitting layer 46 may contain Eu(dbm)3(phen) or CBP doped with Eu(dbm)3(phen). x Tb 1-x (acac)3(phen) may be contained. DCJTB and FIrpic may also be used as assist dopants.

[0153] The organic light-emitting layer 46 may be configured to exhibit thermally activated delayed fluorescence (TDFM). This can be achieved by reducing the energy difference between the excited singlet state and the excited triplet state, or by using thermal energy to efficiently induce reverse energy transition from the excited triplet state to the excited singlet state, thereby producing thermally activated delayed fluorescence (TDFM). Specifically, the organic light-emitting layer 46 may be composed of, for example, PVCz (host material) doped with 2 wt. % SnF2 (OEP) (guest material). Alternatively, the organic light-emitting layer 46 may be composed of 1,3-bis(9-carbazolyl)benzene (mCP) doped with 6 wt. % PIC-TRZ.

[0154] The organic light-emitting layer 46 may include multiple light-emitting layers that emit different colors. By stacking multiple light-emitting layers that emit different colors, it is possible to adjust the color that is ultimately emitted. For example, the organic light-emitting layer 46 may include a TPD layer that emits blue light and an Alq3 layer doped with Nile Red that emits green and red light and is stacked on the TPD layer via an adjustment layer. This configuration allows the organic light-emitting layer 46 to emit white light. [Electron transport layer 48]

[0155] The electron transport layer 48 can be made of a conventionally known material that is generally used in the organic EL device 10. Examples of materials that can be used for the electron transport layer 48 include (1) Alq3, (2) Bphen (4,7-Diphenyl-1,10-phenanthroline), (3) TPBi (2,2',2''-(1,3,5-Benzinetriyl)-tris(1-phenyl-1-H-benzimidazole)), (4) TAZ (3-(4-Biphenyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole), (5) TmPyPB (1,3,5-Tris(3-pyridyl-3-phenyl)benzene), (6) BeBq2 (1,3,5-Tris(3-pyridyl-3-phenyl)benzene), and (7) TSPO1 (iphenyl[4-(triphenylsilyl)phenyl]phosphine oxide), (8)T2T(2,4,6-tris(biphenyl-3-yl)-1,3,5-triazine), (9)BAlq(Bis(2-methyl-8-quino;-Biphenyl-4-olato)aluminum), (10)BCP(Bis(2 -methyl-8-quino;-Biphenyl-4-olato)aluminum), (11)Liq(8-Hydroxyquinolinolato-lithium), (12)NTAZ(4-(naphthalen-1-yl)-3,5-diphenyl- 4H-1,2,4-triazole), (13)Be(PP)2(Bis[2-(2-hydroxyphenyl)-pyridine]beryllium), (14)B3PyPB(1,3-Bis[3,5-di(pyridin-3-yl)phenyl]benze ne), (15)3TPYMB (Tris(2,4,6-trimethyl-3-(pyridin-3-yl)phenyl)borane), (16)DPPS(Diphenyl-bis(4-(pyridin-3-yl)phenyl)silane), and the like.Further examples include oxadiazole derivatives (tBu-PBD), oxadiazole dimers (OXD-7), starburst oxadiazole, TRAZ, phenylquinoxaline derivatives (TPQ), silole derivatives (PyPySPyPy), CBP, benzimidazole derivatives (TPBI), pyrimidine derivatives (B3PymPm), and BpyOXD. Furthermore, in order to introduce a main group element other than carbon or nitrogen, the material of the electron transport layer 48 may include a boron derivative (BMB-nT) or a phosphine oxide derivative (POPy2) (same as above for cited references, etc.). [Electron injection layer 50]

[0156] The electron injection layer 50 can be made of a conventionally known material that is generally used in the organic EL device 10. Examples of materials that can be used for the electron injection layer 50 include materials with a small work function and high activity, such as LiF, Li2O3, Ca, Ba, Cs, and LiF / Ca. [Cathode 60]

[0157] The cathode 60 can be made of a conventional material commonly used in the organic EL device 10. Examples of materials that can be used for the cathode 60 include metals such as lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, aluminum, scandium, vanadium, zinc, yttrium, indium, cerium, samarium, europium, terbium, and ytterbium, as well as alloys of two or more of these metals; alloys of one or more of these metals with one or more of gold, silver, platinum, copper, manganese, titanium, cobalt, nickel, tungsten, and tin; graphite or graphite intercalation compounds; and the like. Examples of such alloys include magnesium-silver alloys, magnesium-indium alloys, magnesium-aluminum alloys, indium-silver alloys, lithium-aluminum alloys, lithium-magnesium alloys, lithium-indium alloys, and calcium-aluminum alloys. For example, the cathode 60 may be composed of alloys of MgAg, MgIn, or AlLi (as cited above). [Thin film sealing layer 70]

[0158] Like the barrier layer described above, the thin-film encapsulating layer 70 is a layer that has high blocking properties against moisture and oxygen. Providing the thin-film encapsulating layer 70 contributes to suppressing degradation of the organic EL element 10's performance due to the intrusion of moisture and oxygen into the organic EL element 10. The thin-film encapsulating layer 70 is provided on the cathode 60 and can be formed to cover the organic EL element 10 except for a portion of the current collector exposed for connection to an external terminal. The thin-film encapsulating layer 70 can be formed using a conventionally known composition, structure, and formation method commonly used for organic EL elements 10, and preferably has the same composition and structure as the barrier layer described above. It is particularly preferable to use the thin-film encapsulating layer 70 (TFE) disclosed in Non-Patent Document 3 as the thin-film encapsulating layer 70. [Example]

[0159] The present invention will be described in more detail below using examples and comparative examples, but the present invention is not limited to the following examples. <<Reference example S1>>

[0160] The suitability of the metal grid transparent electrode, which is made of thin metal wires containing copper and copper oxide, for the PEDOT:PSS film formation process will be specifically explained below. <<Manufacturing of metal grid transparent electrodes>> [Preparation of transparent substrate S] A polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name: Cosmoshine A4100, film thickness 50 μm) with an easy-adhesion layer formed on one side was used as a core layer, and an intermediate layer-forming composition composed of 2 mass% silicon oxide nanoparticles, 1 mass% conductive organic silane compound, 65 mass% 2-propanol, 25 mass% 1-butanol, and 7 mass% water was applied to the other side where the easy-adhesion layer was not formed, and dried to obtain a transparent substrate S with a 150 nm thick intermediate layer containing silicon oxide. [Ink 1]

[0161] 20 parts by mass of cuprous oxide nanoparticles with a particle diameter of 21 nm, 4 parts by mass of a dispersant (manufactured by BYK-Chemie, product name: Disperbyk-145), 1 part by mass of a surfactant (manufactured by Seimi Chemical, product name: S-611), and 75 parts by mass of ethanol were mixed and dispersed to prepare Ink 1 with a cuprous oxide nanoparticle content of 20% by mass. [Manufacturing of Metal Grid Transparent Electrode S]

[0162] First, ink 1 was applied to the surface of a transfer medium. Then, the ink-coated surface of the transfer medium was placed opposite a plate with conductive pattern grooves, and the plates were pressed together to transfer some of the ink on the surface of the transfer medium to the raised portions of the plate. The remaining ink-coated surface of the transfer medium was then placed opposite a transparent substrate S, and the plates were pressed together to transfer the desired conductive pattern of ink 1 onto the intermediate layer of the transparent substrate S. Next, the conductive pattern ink coating film (dispersion coating film) on the transparent substrate was irradiated with 0.9 kW plasma in a reducing atmosphere for 180 seconds, reducing the cuprous oxide in the dispersion coating film to copper. A sintering process was carried out to form a copper metal component sintered film, yielding a mesh-pattern metal grid transparent electrode S. <Evaluation of metal grid transparent electrodes> [Measurement of line width, gap, and film thickness]

[0163] The metal grid transparent electrode S thus obtained was photographed using a confocal laser microscope to determine the line width W of the metal thin lines. TCE and film thickness t TCE , the gap G of the conductive pattern 24P TCE The W of the metal grid transparent electrode S was calculated. TCE is 1.1 μm, t TCE is 153 nm, G TCE was 98.5 μm. [STEM-EDX analysis of cross-section of metal wire]

[0164] The obtained metal grid transparent electrode S was sliced ​​into thin sections with a thickness of 200 nm or less, including a cross section of the metal thin wire perpendicular to the extension direction of the metal thin wire, using a focused ion beam (FIB). The obtained thin section was attached to the tip of a silicon sample stage and used as a measurement sample for STEM-EDX measurement under the following conditions.

[0165] STEM: Hitachi High-Technologies Corporation, scanning transmission electron microscope HD-2300A EDX: Manufactured by EDAX, energy dispersive X-ray analyzer, GENESIS Accelerating voltage: 200 kV Measurement magnification: 25,000x Electron beam incident angle: 90° X-ray extraction angle: 18° Mapping elements: Cu, O Accumulation count: 200 times Dwell time: 200 μsec. Resolution: 256 x 200 pixels

[0166] Next, the measurement sample obtained as described above was observed by STEM to obtain a STEM image of the cross section of the metal thin wire. At the same time, elemental mapping of the cross section of the metal thin wire was performed by energy dispersive X-ray analysis (EDX). Specifically, the EDX intensity of the K shell of oxygen atoms O and the EDX intensity of the K shell of copper atoms Cu were measured for each location on the cross section, and this operation was performed for the entire cross section of the metal thin wire.

[0167] On the other hand, from the STEM image, the maximum thickness t TCE Calculate the thickness from the interface of the metal wire on the transparent substrate side to 0.10t TCE ~0.90t TCE The integrated value of the EDX intensity of the K-shell of oxygen atoms O and the integrated value of the EDX intensity of the K-shell of copper atoms Cu in the thickness region up to 1000 nm were calculated, and the ratio of these integrated values ​​was calculated as the atomic % ratio O / Cu. 0.10 ~ 0.90 Similarly, from the interface of the metal thin wire on the transparent substrate side, 0.10t TCE ~0.25t TCEThe atomic percentage ratio O / Cu was measured in the thickness range of 0.75T to 0.90T by the same method. 0.10-0.25 and atomic % ratio O / Cu 0.75-0.90 The oxygen atoms O are thought to be derived mainly from copper oxides (cuprous oxide, cupric oxide, and / or copper hydroxide). Therefore, the atomic % ratio O / Cu 0.10 ~ 0.25 indicates the interface side with the transparent substrate, and the atomic percentage of O / Cu 0.75-0.90 indicates the uneven distribution of copper oxide on the surface side. The results are shown in Table 1. [Table 1]

[0168] Table 1 shows that oxygen atoms O (i.e., copper oxide) in the thin metal wires of the metal grid transparent electrode S are present in relatively large amounts near the interface on the transparent substrate side. This is thought to be because the reduction of cuprous oxide during plasma sintering proceeds from the surface of the thin metal wires, leaving a large amount of unreduced copper oxide, such as cuprous oxide, near the interface with the transparent substrate. [Compatibility test for PEDOT:PSS film formation process] Next, a PEDOT:PSS aqueous coating solution (product name: Clevios PVP AI 4083, pH 1.5-2.5) was spin-coated onto a metal grid transparent electrode fabricated in the same manner as for the metal grid transparent electrode S, forming a hole injection layer composed of PEDOT:PSS. The sheet resistance of the metal grid transparent electrode S before the PEDOT:PSS film deposition was 330 Ω / sq., but after deposition, the sheet resistance was unmeasurable (overrange), confirming that the thin metal wires had peeled off from the transparent substrate S. We speculate that this is because copper oxide present near the interface with the transparent substrate dissolved in the organic sulfonic acid derived from PSS in the aqueous coating solution, causing under-etching of the thin metal wires, resulting in their peeling from the transparent substrate. This result indicates that wet deposition of PEDOT:PSS is not possible on metal grid transparent electrodes with thin metal wires containing copper and copper oxide. <<Example A>>

[0169] Hereinafter, an organic EL element using a metal grid transparent electrode having thin metal wires containing copper and copper oxide will be specifically described. Example A1 <<Manufacturing of metal grid transparent electrodes>> [Preparation of transparent substrate A]

[0170] A non-alkali glass (manufactured by Corning, product name: EAGLE XG, thickness 1.1 mm) was used as the transparent substrate A. [Manufacturing of metal grid transparent electrode A1]

[0171] First, ink 1 was applied to the surface of a transfer medium. Then, the ink-coated surface of the transfer medium was placed opposite a plate having grooves for the conductive pattern and the second conductive pattern, and the plate was pressed against the plate to transfer some of the ink onto the raised surfaces of the plate. The remaining ink-coated surface of the transfer medium was then placed opposite a transparent substrate A, and the plate was pressed against the transparent substrate A to transfer the desired conductive pattern of ink 1 onto the transparent substrate A. Next, the conductive pattern-form ink coating film (dispersion coating film) on the transparent substrate was irradiated with 1.2 kW plasma in a reducing atmosphere for 600 seconds to reduce the cuprous oxide in the dispersion coating film to copper. A sintered copper metal component film was formed through a firing process, yielding a metal grid transparent electrode A1 having a mesh-pattern conductive pattern and the second conductive pattern. <Evaluation of metal grid transparent electrodes> [Measurement of line width, gap, film thickness, and calculation of aperture ratio]

[0172] The metal grid transparent electrode A1 thus obtained was photographed by a confocal laser microscope to determine the line width W of the thin metal wires in the conductive pattern. TCE and film thickness t TCE , the gap G of the conductive pattern TCE The results are shown in Table 3. The line width W of the thin metal wires of the second conductive pattern of the metal grid transparent electrode A1 was also calculated. Bus is 2 μm, the gap is G Bus 2 μm, and the occupied area ratio S BusThe second conductive pattern was electrically connected to the conductive pattern and was used as a current collector on the anode side. [Measurement of visible light transmittance]

[0173] Visible light transmittance T of the metal grid transparent electrode A1 VLT is the ratio of the visible light transmittance of transparent substrate A to the aperture ratio of conductive pattern A TCE The results are shown in Table 3. [Sheet resistance measurement]

[0174] The sheet resistance of the conductive pattern of the metal grid transparent electrode A1 was measured by a non-contact method using eddy current in accordance with ASTM F 673-02. The results are shown in Table 3. <<Adjustment of the doped hole injection layer>> [Preparation of doped hole injection layer]

[0175] Using a small molecule host material and a small molecule dopant obtained from Shine Materials Technology Co. Ltd., a number of measurement samples were prepared by co-evaporation using a vacuum evaporation system (Kurt J. Lesker, product name: Super Spectros thin-film deposition system) to form a doped hole injection layer on a glass substrate and on a comb-shaped electrode on the glass substrate. The doped hole injection layer of each measurement sample was adjusted to a dopant density N by adjusting the evaporation rate (Å / sec) and evaporation time (sec) of the small molecule host material and the small molecule dopant. p At 5vol%, 10vol%, and 15vol%, the film thickness t HIL was adjusted in the range of 30 nm to 170 nm. [Measurement of electrical conductivity]

[0176] The electrical resistance between the interdigital electrodes of the measurement sample was measured using a Keithley 2440 source measure manufactured by Keithley, and the electrical conductivity σ was calculated using the method described above. HIL The calculated σ HIL The results of averaging for each dopant density are summarized in Table 2. [Table 2] [Measurement of visible light transmittance]

[0177] The visible light transmittance of the doped hole-injected layer on the glass substrate for each measurement sample was calculated using the following method. Using each measurement sample and a glass substrate as a reference sample, the optical absorption spectrum of the doped hole-injected layer was measured, eliminating the influence of the glass substrate. The transmission spectrum was calculated from the obtained optical absorption spectrum, and the visible light transmittance was calculated from the transmission spectrum of the doped hole-injected layer in accordance with JIS R 3106:2019 or ISO 9050:2003. This yielded a calibration curve for the visible light transmittance of the doped hole-injected layer as a function of dopant density and film thickness. <<Manufacturing of organic EL elements>> [Deposition of organic functional layers]

[0178] An organic functional layer with the following composition was formed on the metal grid transparent electrode A1 by vacuum deposition using a vacuum deposition system (Kurt J. Lesker, product name: Super Spectros thin-film deposition system) using low-molecular-weight organic materials obtained from Shine Materials Technology Co. Ltd. The dopant density and film thickness of the doped hole injection layer were adjusted by adjusting the deposition rate (Å / sec) and deposition time (sec) during co-deposition of the low-molecular-weight host material and low-molecular-weight dopant.

[0179] Doped hole injection layer: thickness t HIL 50nm, dopant density N p 5vol% Hole injection layer: thickness t HTL 150nm Organic light-emitting layer: 15 nm thick, containing blue and yellow fluorescent guest materials Electron transport layer: 35 nm thick

[0180] Organic functional layer thickness t org-TCEThe thickness of each layer in the organic functional layer was calculated from the deposition rate and deposition time when forming each layer. The thickness of the organic functional layer was calculated from the total thickness of each layer. The σ obtained in "Adjustment of the doped hole injection layer" was HIL The sheet resistance and visible light transmittance of the doped hole injection layer calculated from the calibration curves of the sheet resistance and visible light transmittance are shown in Table 3. [Electron injection layer and cathode deposition]

[0181] On the formed organic functional layer, LiF (thickness: 1 nm) was vacuum-deposited as an electron injection layer, and then Al (thickness: 100 nm) was vacuum-deposited on top of that as a cathode.

[0182] [Formation of sealing layer] Finally, the entire organic EL element was covered with a thin film encapsulating layer (TFE) disclosed in Non-Patent Document 3, except for a part of the current collecting portion exposed for connection with an external terminal, to produce an organic EL element.

[0183] <Evaluation of current density-voltage-luminance characteristics (JVL characteristics) of organic EL elements> The JVL characteristics of the obtained organic EL element were evaluated. Figure 8 shows the JVL characteristics. Figure 9 shows a photograph of the appearance of the organic EL element when 4 V was applied. From the JVL characteristics, it was found that the light emission threshold voltage was 2.3 V. Therefore, the leakage current of this organic EL element was defined as the current density when an applied voltage of 1 V was applied. Table 3 shows the leakage current and brightness when 4 V was applied.

[0184] [Examples A2 to A7 and Comparative Examples A1 to A2] Line width W in the conductive pattern of the metal grid transparent electrode TCE and Gap G TCE The thickness of the metal thin wires was changed as shown in Table 3 by changing the groove pattern of the plate used in the pattern formation process. TCE was changed as shown in Table 3 by changing the thickness of the ink applied on the surface of the transfer medium in the pattern formation process. p and film thickness t HILThe deposition rate and deposition time during co-evaporation were changed as shown in Table 3. Furthermore, for Comparative Examples A1 and A2, instead of the doped hole injection layer, a hole injection layer (thickness: 10 nm) composed solely of a low molecular weight host material different from those used in Examples A1 to A7 was formed by vacuum deposition on the electrode portion of the metal grid transparent electrode. Furthermore, a hole transport layer (thickness: 40 nm) composed of a combination of low molecular weight host materials different from those used in Examples A1 to A7 was formed by vacuum deposition on the hole injection layer. Other than that, metal grid transparent electrodes and organic EL devices using the same were fabricated and evaluated using the same procedures as in Example A1. The results are shown in Table 3.

[0185] [Table 3] Example A8

[0186] <Cross-section SEM analysis of organic EL elements> Metal grid: The width W of the thin metal lines in the conductive pattern of the transparent electrode TCE is 3 μm, and the film thickness t TCE is 159 nm, and the gap G of the conductive pattern TCE A metal grid transparent electrode was fabricated in the same manner as the metal grid transparent electrode A1, except that the thickness was adjusted to 27 μm. p is 10vol%, and the film thickness t HIL An organic EL device was manufactured in the same manner as in Example A1, except that a doped hole injection layer with a thickness adjusted to 100 nm was provided. A cross section of the resulting organic EL device was prepared using a Nova200 NanoLab FIB-SEM manufactured by FEI, including a cross section of the thin metal wires perpendicular to the extension direction of the thin metal wires, and a cross-sectional SEM image of the laminate of the organic EL device was obtained. The cross-sectional SEM image is shown in Figure 10. Figure 10 shows that the organic functional layer completely covers the thin metal wires.

[0187] Examples A1 to A7 and Reference Example S1 show that forming a doped hole injection layer and a hole transport layer made of a low-molecular-weight organic material by vapor deposition on a conductive pattern made of thin metal wires containing a metal component M (e.g., copper) and an oxide of the metal component M (e.g., copper oxide) can solve problems such as damage to the thin metal wires and peeling of the thin metal wires from the transparent substrate during the manufacturing process of an organic EL device, and can realize an organic EL device using a metal grid transparent electrode having the thin metal wires. Furthermore, cross-sectional SEM images of the organic EL devices of Examples A1 to A7, Comparative Examples A1 to A2, and Example A8 show that the film thickness t TCE For a metal grid transparent electrode with a thickness of 50 nm to 250 nm, the doped hole injection layer and hole transport layer are made thicker than conventional layers, and the total thickness of the organic functional layer is t org-TCE (t org-TCE -t TCE ) in the range of 50 nm to 300 nm, electrical shorts and leakage currents can be suppressed, and an organic EL element using a metal grid transparent electrode with high brightness can be obtained.

[0188] That is, in Examples A1 to A7 and Comparative Examples A1 to A2, the thickness t TCE Although the thicknesses of the hole injection layer and hole transport layer in Examples A1 to A7 are common in that they are 50 nm or more and 250 nm or less, the thicknesses of the hole injection layer and hole transport layer in Comparative Examples A1 and A2 are 10 nm and 40 nm, respectively, while the thicknesses of the hole injection layer and hole transport layer in Examples A1 to A7 are larger at 30 to 120 nm and 150 nm, respectively. As a result, the thickness of the organic functional layer in Comparative Examples A1 and A2 is 140 nm, while the thickness of the organic functional layer in Examples A1 to A7 is 230 to 320 nm.

[0189] Because it is known that luminance decreases with increasing film thickness, the film thickness of the organic functional layer in a typical organic EL device is 100 to 200 nm, as in Comparative Examples A1 and A2. However, the organic functional layers in Examples A1 to A7 have thicknesses of 230 to 320 nm by intentionally increasing the film thicknesses of the hole injection layer and hole transport layer. By adopting such a configuration, it became possible to suppress leakage current and improve luminance. In addition, the inclusion of a doped hole injection layer made it possible to improve luminance uniformity. Thus, by adopting the configurations of Examples A1 to A7, it became possible to provide organic EL devices that have improved luminance while suppressing problems such as peeling in organic EL devices equipped with a metal grid transparent electrode. <<Example B>>

[0190] The following will specifically explain the preferred range of design for a metal grid transparent electrode for improving the brightness of an organic EL element using the metal grid transparent electrode. <Simulation of an organic EL element using a metal grid transparent electrode> 〔simulation〕

[0191] A simulation of an organic EL device using the metal grid transparent electrode of Example A1 was performed using FLUXiM AG's large-area organic semiconductor simulator software LAOSS. The voltage distribution and spatial luminance distribution of the doped hole injection layer / metal grid transparent electrode were calculated using two-dimensional finite element modeling (2D FEM). Specifically, the voltage distribution was calculated by calculating a differential equation that represents the relationship between the local current density calculated based on the voltage at each element and the JV (current density-voltage) characteristics converted from experiments, and the voltage drop according to Ohm's law as the local current density diffuses in the planar direction of the metal grid transparent electrode until the equation converged for the entire system. The spatial luminance distribution was calculated based on the calculated voltage distribution (surface potential distribution) and the LV (luminance-voltage) characteristics converted from experiments. The input parameters for the simulation were as follows:

[0192] Conductive pattern settings: Mesh pattern, WTCE 3 μm, G TCE 27 μm Sheet resistance of the metal wiring part of the metal grid transparent electrode: 1.257Ω / sq. Sheet resistance of doped hole injection layer: 2.129×10 9 Ω / sq. Applied voltage: 4V [Comparison of simulation and actual measurements]

[0193] FIG. 11 shows a comparison of the simulation of the spatial luminance distribution ((A) of the same figure) and the actual measurement (optical microscope image of the organic EL element emitting light in Example A1) ((B) of the same figure) when an applied voltage of 4 V is applied to the square mesh pattern 24P1. It was confirmed that the simulation was able to qualitatively reproduce the spatial luminance distribution of the actual measurement. Specifically, the tendency for the luminance to be greatest near the outside of the metal wiring and to drop sharply as the distance from the metal wiring increases was reproduced. The luminance of the organic EL element calculated by the simulation was 569 cd / m 2 The actual measured value is 357 cd / m 2 A value close to this was obtained. More specifically, the simulation shown in Figure 1(A) showed a spatial brightness distribution in which the brightness was highest near the thin metal wires 24 and decreased as the distance from the thin metal wires 24 increased toward the center of the rectangular region surrounded by the thin metal wires 24. Similarly, the actual measurement shown in Figure 1(B) showed a spatial brightness distribution in which the brightness was highest near the thin metal wires 24 and decreased as the distance from the thin metal wires 24 increased toward the center of the rectangular region surrounded by the thin metal wires 24 increased. [Design optimization of metal grid transparent electrodes through simulation]

[0194] Using this simulation, the metal wiring line width W TCE 0.25μm~10μm, conductive pattern gap G TCE , G TCE / W TCE is 1.0 or more and G TCE The brightness was calculated by simulation when the line width was changed within a range of 100 μm or less. TCESimilarly, Fig. 13 shows the simulated brightness (G TCE A TCE ) indicates dependency.

[0195] From Figure 12, the metal wiring width W TCE At the same time, the gap G of the conductive pattern is adjusted to 0.25 μm or more and 5.0 μm or less. TCE , G TCE / W TCE is 1.0 or more and G TCE It can be seen that the brightness of an organic EL element using a metal grid transparent electrode can be improved by adjusting the aperture ratio of the conductive pattern to A TCE Then, (G TCE A TCE It can be seen that the brightness of organic EL devices using metal grid transparent electrodes can be further improved by adjusting the diffusion length (G TCE ) to make the spatial brightness distribution uniform, and at the same time, TCE By reducing the aperture ratio (A TCE This indicates that the brightness of the organic EL element can be improved by increasing the shading effect (reducing the light-shielding effect). <<Example C>>

[0196] Hereinafter, an organic EL device using a metal grid transparent electrode provided with a transparent conductive inorganic compound layer will be specifically described. Example C1 <<Production and Evaluation of Metal Grid Transparent Electrode C1>>

[0197] A metal grid transparent electrode C1 was produced in the same manner as the metal grid transparent electrode A1, except that a 130 nm thick ITO film was formed on the conductive pattern by sputtering. A planar photograph of the obtained metal grid transparent electrode A1 taken with a confocal laser microscope revealed the line width W of the thin metal lines of the conductive pattern. TCE and film thickness t TCE , the gap G of the conductive pattern TCEThe results are shown in Table 4.

[0198] <<Production and Evaluation of Organic EL Devices>> On the obtained metal grid transparent electrode C1, dopant density N p is 10vol%, and the film thickness t HIL An organic EL device was manufactured and evaluated in the same manner as in Example A1, except that a doped hole injection layer with a thickness adjusted to 100 nm was provided. The results are shown in Table 4. FIG. 14 shows an optical microscope image of the organic EL device of Example C1 emitting light at an applied voltage of 4 V. As shown in the figure, light emission with sufficient brightness was obtained in the rectangular region surrounded by the thin metal wires 24. [Table 4]

[0199] Examples A1 and C1 show that providing a transparent conductive inorganic compound layer such as ITO on the conductive pattern further improves brightness. Comparing the optical microscope image of the organic EL element of Example A1 in Figure 11 (Figure 11(B)) with Figure 13, it is believed that holes diffuse into the openings of the conductive pattern through the transparent conductive inorganic compound layer, thereby uniforming the spatial brightness distribution at the openings and further improving the brightness of the organic EL element. [Industrial Applicability]

[0200] The organic electroluminescence element of the present invention using the metal grid transparent electrode, which suppresses electrical short circuits and leakage current and further improves brightness, can be suitably used to increase the area and flexibility of organic EL elements, and has industrial applicability.

[0201] As described above, the metal grid transparent electrode of the organic EL element according to this embodiment has a thickness of 50 nm or more, and therefore can have a lower electrical resistance than a typical metal grid transparent electrode having a thickness of 10 nm or less that is manufactured by a normal semiconductor process or the like.

[0202] Furthermore, increasing the thickness of the metal grid transparent electrode makes it necessary to improve its smoothness. However, when PEDOT:PSS, which is used to improve smoothness, is applied to a metal grid transparent electrode with thin metal wires composed of a metal and its oxide, the thin metal wires tend to peel off. This issue was noticed by the inventors of the present application, and they came up with the idea of ​​covering the thin metal wires with an organic functional layer including a doped hole injection layer made of a low-molecular-weight organic material. As described above, by not covering the thin metal wires with PEDOT:PSS, which is a polymer, it is possible to suppress the peeling problem. Furthermore, using a doped hole injection layer as the hole injection layer promotes hole diffusion into the aperture, thereby improving the brightness uniformity of the organic EL device.

[0203] In addition, when the thickness of the thin metal wires is 50 nm to 250 nm, by making the difference between the thickness of the organic functional layer and the thickness of the thin metal wires 50 nm or more, i.e., by making the thickness of the organic functional layer 100 nm or more, it becomes possible to cover the thin metal wires and suppress problems such as short circuits and leakage current. On the other hand, by making the difference between the thickness of the organic functional layer and the thickness of the thin metal wires 750 nm or less, i.e., by making the thickness of the organic functional layer 1000 nm or less, it becomes possible to suppress the decrease in brightness caused by the thickness.

[0204] For example, the sum of the thickness of the doped hole injection layer made of a low-molecular organic material that constitutes the organic functional layer and the thickness of the doped hole transport layer made of a low-molecular organic material may be equal to or greater than the thickness of the metal thin wire and may be equal to or greater than 200 nm.

[0205] As mentioned above, a transparent conductive inorganic compound layer such as ITO may be inserted between the thin metal wires and the organic functional layer, which can improve the brightness uniformity of the organic EL element.

[0206] The thin metal wires of the metal grid transparent electrode may also be manufactured by a printing method. Forming the thin metal wires by a printing method makes it possible to easily provide thin metal wires with a thickness of 50 nm or more. In addition, the gap between the thin metal wires, the line width, and the like can be easily changed. The inventors of the present application have noted that if the gap between the thin metal wires is too small, the thin metal wires block light, resulting in a decrease in brightness. Conversely, if the gap is too large, holes do not diffuse sufficiently into the openings, resulting in a decrease in brightness. Based on this finding, they have derived the range of the product of the gap and the aperture ratio to increase brightness, as described above.

[0207] Furthermore, the present invention can be modified in various ways without departing from the spirit of the present invention. For example, some components of one embodiment can be added to other embodiments within the scope of ordinary creativity of a person skilled in the art. Also, some components of one embodiment can be replaced with corresponding components of other embodiments. [Explanation of symbols]

[0208] 10 Organic EL element 20 Metal grid transparent electrode 22 Transparent base material 24 Fine metal wire 24P conductive pattern (electrode part) 24P1 mesh pattern (square) 24P2 mesh pattern (rectangle) 24P3 mesh pattern (diamond) 24P4 honeycomb pattern 24P5 line pattern 26P Second conductive pattern (current collecting part) 40 Organic functional layer 42 Doped hole injection layer 44 Hole transport layer 46 Organic light-emitting layer 48 Electron transport layer 50 Electron injection layer 60 Cathode 70 Thin film sealing layer (sealing layer) ATCE Opening ratio G TCE Gaps in conductive patterns J leak Leakage Current N p Dopant density of the doped hole injection layer R s_TCE Sheet resistance of metal grid transparent electrodes S Bus Occupancy area ratio of second conductive pattern T VLT Visible light transmittance of metal grid transparent electrodes t HIL Doped hole injection layer thickness t HTL Hole transport layer thickness t TCE Metallic wire thickness t org - TCE Organic functional layer thickness W Bus Line width of the thin metal wires constituting the second conductive pattern W TCE Line width of the thin metal wires constituting the first conductive pattern σ HIL Electrical conductivity of the doped hole injection layer

Claims

1. An organic electroluminescence element comprising: a metal grid transparent electrode; a cathode facing the metal grid transparent electrode; and an organic functional layer provided between the metal grid transparent electrode and the cathode, the metal grid transparent electrode comprises a transparent substrate and a conductive pattern having metal wiring provided on the transparent substrate; the metal wiring comprises a metal and an oxide of the metal; the organic functional layer includes a doped hole injection layer formed on the conductive pattern and made of a low-molecular organic material, and a hole transport layer formed on the doped hole injection layer and made of a low-molecular organic material; Furthermore, TCE is the thickness of the metal wiring, and t org-TCE is the film thickness of the organic functional layer, t TCE is 50 nm or more and 250 nm or less, (t org-TCE -t TCE ) is 50 nm or more and 750 nm or less, the doped hole injection layer has a visible light transmittance of 80% or more and 100% or less; The doped hole injection layer is The layer is made of at least two small molecule organic materials. Organic electroluminescent element.

2. W TCE is the line width of the metal wiring, and G TCE is the gap between adjacent metal wirings extending in the same direction, W TCE is 0.25 μm or more and 5.0 μm or less, G TCE is 50 μm or less, and (G TCE / W TCE ) is 1.0 or greater, The organic electroluminescence device according to claim 1 .

3. A TCE is the aperture ratio of the conductive pattern, (G TCE * A TCE ) is 0.6 μm·% or more and 30 μm·% or less, The organic electroluminescence device according to claim 2 .

4. Aperture ratio A of the conductive pattern TCE is 35% or more and less than 100%; The organic electroluminescence device according to claim 3 .

5. t HIL is the film thickness of the doped hole injection layer, t HIL is 30 nm or more and 200 nm or less, The organic electroluminescence device according to claim 1 .

6. t HTL is the thickness of the hole transport layer, t HTL is 30 nm or more and 200 nm or less, The organic electroluminescence device according to claim 1 .

7. σ HIL is the electrical conductivity of the doped hole injection layer, σ HIL is 5 x 10 -5 S / cm or more, The organic electroluminescence device according to claim 1 .

8. The sheet resistance of the doped hole injection layer is 6.5×10 9 Ω / sq. or less, The organic electroluminescence device according to claim 1 .

9. The dopant density N of the doped hole injection layer p is 3 vol% or more and 18 vol% or less, The organic electroluminescence device according to claim 1 .

10. a transparent conductive inorganic compound layer disposed between the metal grid transparent electrode and the dopant hole injection layer; The organic electroluminescence device according to claim 1 .

11. the transparent conductive inorganic compound layer contains indium tin oxide; The organic electroluminescence device according to claim 10 .

12. the metal grid transparent electrode includes a current collecting portion provided on the transparent substrate and having a second conductive pattern electrically connected to the conductive pattern; S Bus is the occupied area ratio of the second conductive pattern per unit area, S Bus is 50% or more and less than 100%; The organic electroluminescence device according to claim 1 .

13. 13. The organic electroluminescence device according to claim 1, wherein the metal is copper.

14. In STEM-EDX analysis of a cross section of the metal wiring perpendicular to the extension direction of the metal wiring of the conductive pattern, TCE ~0.90t TCE The atomic % ratio O / M of oxygen atoms contained in the oxide of the metal to the metal in the thickness region up to 0.10 ~ 0.90 The organic electroluminescence device according to claim 1 , wherein is 0.01 or more and 1.00 or less.

15. The conductive pattern comprises a mesh pattern. The organic electroluminescence device according to claim 1 .

16. The conductive pattern is a plate-based printing process for printing the metal-containing ink on the surface of the transparent substrate so as to form the conductive pattern; The printed ink is baked in a baking step to fuse the metal so as to form a metal component sintered film. The organic electroluminescence device according to claim 1 .

17. The doped hole injection layer is Dopant density N p The low molecular weight host material and the low molecular weight dopant are co-evaporated so that the ...

17. The organic electroluminescence device according to claim 1.

18. Each layer constituting the organic functional layer is formed of a low molecular weight organic material.

18. The organic electroluminescence device according to claim 1.

19. Further comprising a second transparent conductive inorganic compound layer disposed on the transparent substrate, 19. The organic electroluminescence device according to claim 1, wherein the metal grid transparent electrode is provided on the second transparent conductive inorganic compound layer.

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