Thin-film light-emitting element, string-shaped light source using the same, and light source system using the same

Abstract

To provide a thin film light-emitting element having an excellent flexible property.SOLUTION: A thin film light-emitting element has an element Young's modulus equal to or smaller than 10000 Mpa, has the average thickness equal to or smaller than 0.2 mm, and has a ratio equal to or larger than 10, the ratio being between a length in a longer direction of the element and a length in a direction in which the length is the longest of lengths in directions perpendicular to the longer direction.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a thin-film light-emitting element, a strip-shaped light source using the same, and a light source system using the same. [Background technology]

[0002] Light irradiation is used for various purposes, including lighting to obtain brightness, chemical reactions, sterilization, and disinfection. Light sources used for light irradiation vary in shape depending on the application. For example, a lighting device for visual inspection using a curved, hemispherical, or spherical light source, used in visual inspection methods to observe the surface condition of metal articles, has been disclosed (see Patent Document 1). In recent years, attempts have been made to utilize light irradiation for cosmetic purposes and the treatment of injuries and diseases. Examples include portable devices that emit light using organic light-emitting semiconductors and are adapted to conform to the surface of the area to be treated with light, phototherapy patches that conform to non-planar parts of the patient's body, and sealed biocompatible light irradiation devices that include a flexible substrate and a light-emitting element containing an organic semiconductor or quantum dots, enclosed in a protective bag (see Patent Documents 2 to 4). Furthermore, a method has been proposed in which a sheet containing organic electroluminescent elements is applied to the skin and irradiated with light to activate the skin, thereby achieving cosmetic or therapeutic effects (see Patent Document 5 and Non-Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 04-178541 [Patent Document 2] Patent No. 4651281 [Patent Document 3] International Publication No. 00 / 015296 [Patent Document 4] International Publication No. 17 / 038655 [Patent Document 5] Japanese Patent Application Laid-Open No. 2015-142717 [Non-patent literature]

[0004] [Non-Patent Document 1] Yongmin Jeon and 7 others, "Advanced Materials Technologies", 2018, 1700391 [Non-patent document 2] Tomoyuki Yokota and 9 others, "Science Advances", 2016, No. 2, e1501856 Summary of the Invention [Problem to be solved by the invention]

[0005] As mentioned above, light sources are used in various shapes depending on the application. In the fields of beauty and medical treatment, flexible light sources have been proposed, enabling light to be irradiated according to the shape of the area to be irradiated. Beyond these fields, flexible light sources are expected to be used in a variety of applications, including curved surface illumination and decoration of curved structural surfaces. However, because they are, in principle, two-dimensional light sources, they are physically impossible to conform to free-form surfaces, except on stretchable substrates. While there have been research reports on fabricating light-emitting devices on stretchable substrates, several breakthroughs are currently required for practical use due to issues such as manufacturing and device reliability. From this perspective, there is a demand for thin-film light-emitting devices that are practical, highly flexible, and highly conformable to free-form surfaces.

[0006] The present invention has been made in view of the above-mentioned circumstances, and has as its object to provide a thin-film light-emitting device having excellent flexibility. [Means for solving the problem]

[0007] The present inventors have studied thin-film light-emitting elements with excellent flexibility and have discovered that by adjusting a thin-film light-emitting element having a Young's modulus within a predetermined range to a predetermined thickness and shape, a thin-film light-emitting element with excellent flexibility can be obtained, thereby arriving at the present invention.

[0008] That is, the present invention is a thin-film light-emitting element characterized in that the Young's modulus of the element is 10,000 MPa or less, the average thickness is 0.2 mm or less, and the ratio of the longitudinal length of the element to the longest length among the directions perpendicular to the longitudinal direction is 10 or more.

[0009] The thin-film light-emitting element preferably has electrode lead-out portions at both ends in the longitudinal direction of the element.

[0010] The thin-film light-emitting element is preferably an organic electroluminescent element having a structure in which multiple layers are stacked between an anode and a cathode, having one or multiple organic compound layers between the anode and the cathode, and further having the cathode on the substrate side.

[0011] In the organic electroluminescent device, the upper electrode preferably has an average thickness of 20 nm or more.

[0012] The present invention also provides a strip-shaped light source comprising the thin-film light-emitting element of the present invention.

[0013] The present invention also provides a light source system that achieves the effect of a surface light source by using a plurality of strip light sources of the present invention. [Effects of the Invention]

[0014] The thin-film light-emitting element of the present invention has excellent flexibility and excellent conformability to free-form surfaces, and can therefore be suitably used for applications requiring high flexibility, such as illumination of curved surfaces and decoration of the surfaces of curved structures. [Brief explanation of the drawings]

[0015] [Figure 1]FIG. 10 is a diagram showing the results of a nonlinear stress analysis performed on a PET substrate with a Young's modulus of 3000 MPa when it is bent. [Figure 2] FIG. 10 is a diagram showing the results of a nonlinear stress analysis performed on a PET substrate with a Young's modulus of 2000 MPa when it is bent. [Figure 3] This figure shows the results of a nonlinear stress analysis of a string-shaped film with a film thickness of 200 μm and an aspect ratio of 10, subjected to forced rotation around an axis. [Figure 4] This figure shows the results of a nonlinear stress analysis of forced rotation around an axis for a string-like shape with a film thickness of 200 μm and an aspect ratio of 15. [Figure 5] This figure shows the results of a nonlinear stress analysis of a string-shaped film with a film thickness of 100 μm and an aspect ratio of 10, subjected to forced rotation around an axis. [Figure 6] 1 is a schematic diagram showing an example of a laminate structure when the thin-film light-emitting element of the present invention is an organic electroluminescent element. [Figure 7] 1 is a schematic diagram showing an example of a laminate structure when the thin-film light-emitting element of the present invention is an organic electroluminescent element. [Figure 8] 1 is a schematic diagram showing an example of a laminate structure when the thin-film light-emitting element of the present invention is an organic electroluminescent element. [Figure 9] 1 is a schematic diagram showing an example of a laminate structure when the thin-film light-emitting element of the present invention is an organic electroluminescent element. [Figure 10] 1 is a schematic diagram showing an example of a laminate structure when the thin-film light-emitting element of the present invention is an organic electroluminescent element. [Figure 11] 1 is a schematic diagram showing an example of a laminate structure when the thin-film light-emitting element of the present invention is an organic electroluminescent element. [Figure 12] 1 is a schematic diagram showing an example of a laminate structure when the thin-film light-emitting element of the present invention is an organic electroluminescent element. [Figure 13] 1 is a schematic diagram showing an example of a laminate structure when the thin-film light-emitting element of the present invention is an organic electroluminescent element. [Figure 14] 1 is a schematic diagram showing an example of a laminate structure when the thin-film light-emitting element of the present invention is an organic electroluminescent element. [Figure 15] 1 is a schematic diagram showing an example of a laminate structure when the thin-film light-emitting element of the present invention is an organic electroluminescent element. [Figure 16] 1 is a schematic diagram showing an example of a laminate structure when the thin-film light-emitting element of the present invention is an organic electroluminescent element. [Figure 17] 1 is a photograph showing the thin-film light-emitting element produced in Example 1, wound around a glass rod having an outer diameter of 3 mm, emitting light. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present invention will be described in detail below. In addition, a combination of two or more of the individual preferred embodiments of the present invention described below is also a preferred embodiment of the present invention.

[0017] The thin-film light-emitting element of the present invention is characterized in that the element has a Young's modulus of 10,000 MPa or less, an average thickness of 0.2 mm or less, and a ratio (aspect ratio) of the length of the element in the longitudinal direction to the longest direction perpendicular to the longitudinal direction of the element of 10 or more. The present invention aims to achieve this by studying the conditions under which a thin-film light-emitting element can have excellent conformability to a free-form surface and realizing an element that can be twisted. The inventors calculated the conditions for an element that can be twisted by performing a bending test using a film light source with an element thickness of 0.1 mm and a mechanical simulation. (1) First, using the 0.1 mm thick organic electroluminescent device (device size: 3.5 cm x 3.5 cm) prepared in Example 1 of Japanese Patent Application No. 2021-071277, a bending test was conducted 100,000 times at a bending radius of 2 mm using a bending tester manufactured by Yuasa System Co., Ltd. It was confirmed that there was no change in the visual unevenness of light emission before and after the test, and furthermore, there was no change in the voltage-luminance characteristics at multiple light-emitting positions. This confirmed that the characteristics of the thin-film light-emitting device were not affected by the stress applied under these conditions. (2) Next, the stress that the element receives under the conditions of this bending test was calculated by a mechanical simulation under the following conditions, and the generated stress was estimated to be about 100 MPa. These results indicate that the thin film light emitting device under the above conditions is not affected by a stress of at least about 100 MPa. <Mechanical simulation of stress in bending tests> The analysis method is as follows. A nonlinear stress analysis was performed using a continuum simulation. It was confirmed that the final state could be reproduced by multi-stage bending. The usage model is as follows: Homogeneous linear elastic body (plasticity not considered) Young's Modulus: Variable Poisson's ratio: 0.4 (PET bulk property value) Shell primary accuracy (thickness 0.1mm) Mesh pitch 1mm Since the Young's modulus of PET, the base material of the organic electroluminescent device subjected to the bending test, was 2000 to 3000 MPa, stress analysis was performed when the device was bent for a Young's modulus of 3000 MPa and a Young's modulus of 2000 MPa. The analysis results are shown in Figures 1 and 2, respectively. The stress analysis showed that when the Young's modulus was 3000 MPa, an equivalent stress of about 95 MPa occurred at the bent portion, and when the Young's modulus was 2000 MPa, an equivalent stress of about 63 MPa occurred at the bent portion. From these results, it was estimated that the maximum stress generated under the bending test conditions in (1) above was about 100 MPa. (3) Furthermore, using these results, we performed a simulation under the following conditions to determine what conditions would result in an element in which the stress generated by torsion, which is the target of the present invention, would be less than 100 MPa. <Mechanical simulation of stress in torsion> The analysis method is as follows. A nonlinear stress analysis was performed using a continuum simulation to calculate the stress caused by forced rotation around the axis. The usage model is as follows: Homogeneous linear elastic body (plasticity not considered) Young's modulus: 10000Mpa Poisson's ratio: 0.4 (PET bulk property value) Shell primary accuracy (thickness 0.2mm) Mesh pitch 0.5mm The analysis results for a string-like shape with a film thickness of 200 μm and an aspect ratio of 10, a string-like shape with a film thickness of 200 μm and an aspect ratio of 15, and a string-like shape with a film thickness of 100 μm and an aspect ratio of 10 are shown in Figures 3 to 5, respectively. As a result of the analysis, the maximum stress when twisted for the string-like shape with a film thickness of 200 μm and an aspect ratio of 10 was approximately 110 MPa. Furthermore, for the film thickness of 200 μm and an aspect ratio of 15 and for the film thickness of 100 μm and an aspect ratio of 10, the maximum stress when twisted was 70 MPa and 40 MPa, respectively. These simulation results showed that the criteria for a stress equivalent to 100 MPa on the element are a Young's modulus of 10,000 MPa, a film thickness of 0.2 mm, and an aspect ratio of 10. It is clear that good elements can be obtained in directions where the stress is smaller than these, and therefore, from the perspective of materials engineering, elements with physical properties of a Young's modulus of 10,000 MPa or less, a film thickness of 0.2 mm or less, and an aspect ratio of 10 or more will be subjected to a stress of 100 MPa or less, and will be unaffected by twisting. The present invention has discovered that by forming an element having a Young's modulus of 10,000 MPa or less into a shape with an average thickness of 0.2 mm or less and an aspect ratio of 10 or more, it becomes a highly flexible light-emitting element that can also be twisted.

[0018] The Young's modulus of the thin-film light-emitting device of the present invention may be 10,000 MPa or less, preferably 5,000 MPa or less, and more preferably 3,000 MPa or less. The Young's modulus of the thin-film light-emitting device can be measured using a tensile tester.

[0019] The thin-film light-emitting device of the present invention may have an average thickness of 0.2 mm or less and an aspect ratio (ratio of the longitudinal length of the device to the longest direction perpendicular to the longitudinal length) of 10 or more, but the average thickness is preferably 0.12 mm or less, more preferably 0.10 mm or less, and even more preferably 0.07 mm or less. From the viewpoint of device handleability, the average thickness is preferably 0.07 μm or more, and more preferably 0.10 μm or more. The thin-film light-emitting element of the present invention may have an elongated shape with an aspect ratio of 10 or more, but the aspect ratio is preferably 15 or more, and more preferably 30 or more. From the viewpoint of handling, the actual length of the shorter side of the length ratio is preferably 1 mm or more, and more preferably 3 mm or more.

[0020] The thin-film light-emitting device of the present invention preferably has electrode lead-out portions at both longitudinal ends of the device. Because the thin-film light-emitting device of the present invention is a thin film, the resistance of the wiring cannot be ignored, resulting in a voltage drop and uneven luminance. One method for preventing this is to arrange the lead-out portions of both electrodes, which are usually arranged close to each other for convenience in wiring arrangement, at the farthest positions. In this case, the upper electrode may be led out not only on one side but also on both sides. Similarly, the lower electrode may be led out not only on one side but also on both sides. This makes it possible to realize a film light source that can be twisted to follow free-form surfaces and has more uniform light emission.

[0021] The string-shaped light source made of the light-emitting element of the present invention is, by itself, merely a linear light source, and is not sufficient for, for example, cosmetic or medical applications that use light to produce effects. Therefore, by arranging multiple string-shaped light sources of the present invention on a free-form surface, it is possible to create a pseudo-planar light source. This makes it possible to provide a light source system of pseudo-planar light sources that can follow the free-form surface.

[0022] Below, we describe the configuration of an organic electroluminescent device that can be used as a thin-film light-emitting device, which has a Young's modulus of 10,000 MPa, an average thickness of 0.2 mm or less, and an aspect ratio of 10 or more, as discovered from the bending test results and simulations of the above-mentioned actual device. Realizing a practical organic electroluminescent device with this thickness and length (the minor axis side cannot maintain a physical distance that takes into consideration the intrusion of water and oxygen) places limitations on the sealing configuration of barrier films, etc., and therefore an organic electroluminescent device that is resistant to water and oxygen and does not rely too much on barrier function is suitable for the organic electroluminescent device of the present invention. The details are as follows.

[0023] The organic electroluminescent element used as the thin-film light-emitting element of the present invention preferably has a structure in which a plurality of layers are stacked between an anode and a cathode, has one or more organic compound layers between the anode and the cathode, and further has the cathode present on the substrate side. Among organic electroluminescent devices, the thin-film light-emitting device is an organic electroluminescent device with a so-called inverted structure in which a cathode is formed on a substrate, making the organic electroluminescent device resistant to water and oxygen and less dependent on a barrier film, resulting in a more flexible thin-film light-emitting device that is practical and has excellent flexibility against twisting, etc.

[0024] The organic electroluminescent device is preferably an element having an electron injection layer and / or electron transport layer, a light-emitting layer, and a hole transport layer and / or hole injection layer, in this order, between a cathode and an anode formed on a substrate. The organic electroluminescent device may have layers other than these layers, such as a hole blocking layer, which will be described later. The organic electroluminescent device is preferably an element having an electron injection layer and / or electron transport layer, an emitting layer, a hole transport layer and / or hole injection layer, which are adjacent to each other in this order between a cathode and an anode formed on a substrate, or more preferably an element having an electron injection layer and / or electron transport layer, a hole blocking layer, an emitting layer, a hole transport layer and / or hole injection layer, which are adjacent to each other in this order between a cathode and an anode formed on a substrate. Each layer constituting these organic electroluminescent devices may consist of one layer or two or more layers.

[0025] Preferred embodiments of the organic electroluminescent device include: (1) an organic electroluminescent device having an organic layer including a light-emitting layer between a cathode and an anode, and a layer in which a metal electron injection layer that is a metal thin film adjacent to the cathode and an organic electron injection layer that contains an organic material that undergoes a coordination reaction with a metal element in the metal layer are laminated; and (2) an organic electroluminescent device having an organic layer including a light-emitting layer between a cathode and an anode, and a cathode that is a layer that contains magnesium, silver, and / or aluminum, where the volume ratio of magnesium is 2% or more and 30% or less, has an average thickness of 40 nm or less, and has an organic electron injection layer adjacent to the cathode that contains an organic material that can form a coordination bond to a metal atom. Hereinafter, the organic electroluminescent device of (1) above will be referred to as an organic electroluminescent device of a first preferred embodiment, the organic electroluminescent device of (2) above will be referred to as an organic electroluminescent device of a second preferred embodiment, and the combination of both will be referred to as an organic electroluminescent device of a preferred embodiment of the present invention. The organic electroluminescent device of the second preferred embodiment exhibits excellent electron injection properties due to the coordinate bond between magnesium and an organic material capable of forming a coordinate bond with a metal atom. Furthermore, by incorporating a small amount of magnesium into the cathode together with silver and / or aluminum to form a layer with an average thickness of 40 nm or less, a device with excellent atmospheric stability can be obtained while using magnesium, which has a low work function. Furthermore, devices with such a configuration have a longer life than previously described devices with a metal oxide layer on the cathode. The mechanism behind this is thought to be that magnesium has denser coordinate bonds than an oxide layer, thereby reducing the injection barrier firmly and uniformly and reducing the intrusion of oxygen and water from the outside.

[0026] Next, the organic electroluminescent device of the present invention will be described in detail with reference to examples. FIG. 6 is a schematic cross-sectional view illustrating an example of the layered structure of an organic electroluminescent device according to a first preferred embodiment. Here, an inverted structure is shown. The organic electroluminescent device 1 of this embodiment shown in FIG. 6 has an emitting layer 8 between a cathode 3 and an anode 11. In the organic electroluminescent device 1 shown in FIG. 6, a metal electron injection layer 5 and an organic electron injection layer 6, which are components of the present invention, are adjacently present between the cathode 3 and the emitting layer 8. Furthermore, an electron transport layer 7 and a hole blocking layer 12 are also present as necessary. A hole transport layer 9 and a hole injection layer 10 are present between the emitting layer 8 and the anode 11. Other examples of the configuration of the organic electroluminescent device according to the first preferred embodiment of the present invention include the configurations shown in FIGS.

[0027] 12 and 13 are schematic cross-sectional views illustrating an example of the layered structure of an organic electroluminescent device according to a second preferred embodiment. Here, an inverted structure is shown. The organic electroluminescent device 1 according to this embodiment shown in FIGS. 12 and 13 has an emitting layer 8 between a cathode 3 and an anode 11. In the organic electroluminescent device 1 shown in FIGS. 12 and 13, an organic electron injection layer 6 is present adjacent to the cathode 3 between the cathode 3 and the emitting layer 8. Furthermore, an electron transport layer 7 and a hole blocking layer 12 are also present as necessary. A hole transport layer 9 and a hole injection layer 10 are present between the emitting layer 8 and the anode 11. Furthermore, a metal oxide layer 4 may be used as a base for the cathode 3 to enhance the stability of the cathode (FIGS. 15 and 16). Another example of the configuration of the organic electroluminescent device according to the second preferred embodiment is the configuration shown in FIG. 14.

[0028] In this embodiment, an organic electroluminescent device 1 having an inverted structure will be described as an example, but the organic electroluminescent device of the present invention may also have a forward structure in which an anode is disposed between a substrate and an emitting layer. Furthermore, the organic electroluminescent device may be a bottom emission device in which light is extracted from the substrate side, or a top emission device in which light is extracted from above the substrate. When the organic electroluminescent device of the first preferred embodiment of the present invention has a forward structure, it has a laminated structure in which the organic electron injection layer and the metal electron injection layer are in contact with each other between the cathode and the light-emitting layer, as in the case of the inverted structure. Furthermore, when the organic electroluminescent device of the second preferred embodiment has a forward structure, it also has an organic electron injection layer adjacent to the cathode between the cathode and the light-emitting layer, as in the case of an inverted structure. The materials, thicknesses, and sealing of each layer constituting the organic electroluminescent element described below are the same for the organic electroluminescent element of the first preferred embodiment as for the organic electroluminescent element of the forward structure, except for the materials of the cathode and anode described later. Only for the top-emission element of the inverted structure, there is no limitation on the thickness of the metal electron injection layer described later, and any thickness is acceptable. Regarding the organic electroluminescent device of the second preferred embodiment, the materials, thicknesses and sealing of each layer constituting the organic electroluminescent device are the same as those of the organic electroluminescent device of the forward structure, except for the material of the anode, which will be described later. The materials for each layer of the organic electroluminescent device will be described below.

[0029] "substrate" Examples of materials for the substrate include resin materials. Examples of resin materials used for the substrate include polyethylene terephthalate, polyethylene naphthalate, polypropylene, cycloolefin polymer, polyamide, polyethersulfone, polymethyl methacrylate, polycarbonate, polyarylate, etc. When a resin material is used as the substrate material, an organic electroluminescent device having excellent flexibility can be obtained, which is preferable.

[0030] When the organic electroluminescent device is a bottom emission type, a transparent substrate is used as the substrate material. When the organic electroluminescent element is a top-emission type, the substrate may be an opaque substrate as well as a transparent substrate. Examples of opaque substrates include a substrate in which an oxide film (insulating film) is formed on the surface of an ultrathin metal plate such as stainless steel, and a substrate made of a resin material.

[0031] The average thickness of the substrate can be determined depending on the material of the substrate, etc., and is preferably 0.01 to 0.2 mm, more preferably 0.02 to 0.1 mm. The average thickness of the substrate can be measured using a digital multimeter and a vernier caliper.

[0032] "cathode" The cathode is formed on and in direct contact with the substrate. The cathode can be made of transparent conductive materials such as ITO (tin-doped indium oxide), ATO (antimony-doped indium oxide), IZO (indium-doped zinc oxide), AZO (aluminum-doped zinc oxide), or FTO (fluorine-doped indium oxide), or opaque conductive materials such as calcium, magnesium, aluminum, tin, indium, copper, silver, gold, platinum, or alloys of these metals.

[0033] In the organic electroluminescent device according to the first preferred embodiment of the present invention, the cathode material is preferably a material having a work function of 4.0 eV or more, such as conductive oxide materials such as ITO (indium tin oxide), IZO (indium zinc oxide), FTO (fluorine tin oxide), In3O3, SnO2, Sb-containing SnO2, and Al-containing ZnO, as well as silver or a silver alloy. Among these, ITO, IZO, FTO, and silver are preferably used as the cathode material. In the organic electroluminescent device according to the second preferred embodiment of the present invention, the cathode is a layer formed containing magnesium, which is an elemental metal, and silver and / or aluminum. The cathode may contain either silver or aluminum, or both. The volume ratio of magnesium in the layer containing magnesium and silver and / or aluminum is 30% or less. With such a ratio, the device has excellent electron injection properties and also excellent atmospheric stability. The volume ratio of magnesium is preferably 20% or less, more preferably 10% or less, and even more preferably 5% or less. To achieve even better electron injection properties, the volume ratio of magnesium is 2% or more, preferably 3% or more, and more preferably 4% or more. These materials can be used as the anode material when the organic electroluminescent device of the present invention has a forward structure in which the anode is disposed between the substrate and the light-emitting layer. In this case, the average thickness of the anode is preferably the same as that of the cathode. The work function was based on the value described in Journal of Applied Physics, Vol. 48, 1977, p. 4729.

[0034] The average thickness of the cathode is preferably 7 nm or more. Such a thickness can reduce the electrical resistance of the electrode, making the thin-film light-emitting device of the present invention have better light-emitting properties and reducing manufacturing variations. The average thickness of the cathode is more preferably 5 nm or more, and even more preferably 10 nm or more. Furthermore, the average thickness of the cathode is preferably 40 nm or less. With such a thickness, the device has excellent atmospheric stability. The average thickness of the cathode is preferably 35 nm or less, and more preferably 25 nm or less. The average thickness of the cathode can be measured by a stylus step gauge or spectroscopic ellipsometry. In the case of an inverted structure, the cathode is the lower electrode and an auxiliary electrode can be disposed, so the thickness is not very important.

[0035] "Electron injection layer" The electron injection layer may be made of an organic material or an inorganic material. When the electron injection layer is made of an inorganic material, examples of the electron injection layer include a layer consisting of a single metal oxide film, or a semiconductor or insulator laminated thin film layer that is a layer in which a single metal oxide or two or more types of metal oxides are laminated and / or mixed, and examples of the metal element that constitutes the metal oxide include a metal element selected from the group consisting of magnesium, calcium, strontium, barium, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese, indium, gallium, iron, cobalt, nickel, copper, zinc, cadmium, aluminum, and silicon. When the electron injection layer is made of an organic material, examples of the material include nitrogen-containing compounds, such as pyrrolidones such as polyvinylpyrrolidone, pyrroles such as polypyrrole, anilines such as polyaniline, pyridines such as polyvinylpyridine, as well as compounds having a nitrogen-containing heterocycle such as pyrrolidines, imidazoles, piperidines, pyrimidines, and triazines, and amine compounds.

[0036] "Metal electron injection layer" When the organic electroluminescent device is the device of the first preferred embodiment of the present invention, the metal electron injection layer in the device is a layer composed of a metal species that is positioned as the central metal of a metal complex when the material contained in the organic electron injection layer is used as a ligand, so that it can be a thin film functionally, and for bottom emission, transparency is required, so the thickness is preferably 0.1 to 5 nm, more preferably 0.5 to 2 nm. For top emission, transparency is not required, and there is no limit to the thickness. The average thickness of the metal electron injection layer can be measured by a stylus profilometer or spectroscopic ellipsometry.

[0037] The material contained in the metal electron injection layer may be a simple substance of a metal species having coordination ability, but in view of stability in the atmosphere, it is preferable that the material has a work function of 4.0 eV or more. The metal electron injection layer may be a metal layer of a single metal, a layer in which a layer of a mixture of two or more metals and a layer of a single metal are laminated, or a layer in which two or more metals are mixed. The metal electron injection layer may also serve as a cathode. Examples of metal elements that form the metal electron injection layer include copper, nickel, palladium, platinum, gold, cobalt, zinc, aluminum, chromium, manganese, iron, tin, indium, titanium, zirconium, vanadium, niobium, tantalum, molybdenum, tungsten, indium, gallium, and cadmium. The work function was determined based on the value given in Journal of Applied Physics, Vol. 48, 1977, p. 4729. When the metal electron injection layer includes a layer containing a mixture of two or more metal elements, it is preferable that at least one of the metal elements constituting the metal layer is aluminum, zinc, or copper. When the metal electron injection layer is a layer made of one kind of metal, it is preferably a layer made of a metal selected from the group consisting of aluminum, zinc, and copper.

[0038] "Organic electron injection layer" In the organic electroluminescent device of the first preferred embodiment, the organic electron injection layer improves electron injection by forming a complex with the metal electron injection layer. In the organic electroluminescent device of the second preferred embodiment, the organic electron injection layer improves electron injection by forming a complex with magnesium contained in the cathode. In this case, the organic material forming the organic electron injection layer may be any organic material having coordination ability. Among them, compounds having a nitrogen atom-containing substituent are preferred, and compounds having a nitrogen atom-containing heterocyclic fused ring structure are even more preferred. For example, the organic material contained in the organic electron injection layer of the present invention may be a compound having a structure represented by the following general formula (1):

[0039] [ka]

[0040] (In general formula (1), X 1 , X 2 are the same or different and represent a nitrogen atom, an oxygen atom, a sulfur atom or a divalent linking group which may have a substituent. L represents a direct bond or a p-valent linking group. n 1 represents the number 0 or 1, and p represents the number 1 to 4. q represents the number 0 or 1, and when p is 1, q is 0. R 1 ~R 3 are the same or different and represent monovalent substituents. 1~m 3 are the same or different and represent a number from 0 to 3. 1 ~R 3 is X 1 , X 2 may be bonded to form a ring structure. 1 If there are multiple R 1 may be bonded to form a ring structure. 2 , R 3 The same applies to .)

[0041] X in the above general formula (1) 1 , X 2 are the same or different and represent a nitrogen atom, an oxygen atom, a sulfur atom or a divalent linking group which may have a substituent. Examples of the divalent linking group include divalent hydrocarbon groups and groups in which some of the carbon atoms of a hydrocarbon group have been substituted with a heteroatom such as a nitrogen atom, an oxygen atom, or a sulfur atom. The hydrocarbon group preferably has 1 to 6 carbon atoms, and more preferably has 1, 2 or 6 carbon atoms. The hydrocarbon group may be linear, branched, cyclic, or a combination thereof. The divalent hydrocarbon group may be an alkylene group, which is a saturated hydrocarbon group, or an unsaturated hydrocarbon group such as an alkenylene group or an alkynylene group. Specifically, the divalent hydrocarbon group is preferably one represented by the following formulas (2-1) to (2-4). In the following formulas (2-1) to (2-4), R represents a substituent. X, including R in (2-1) to (2-4), 1 , X 2 Specific examples of the substituent in R 1 ~R 3 Examples of the monovalent substituent include the same groups as those of the above.

[0042] [ka]

[0043] In the above general formula (1), L represents a direct bond or a p-valent linking group. Note that L becomes a direct bond only when p is 2. Examples of p-valent linking groups include nitrogen atoms, oxygen atoms, sulfur atoms, and carbon atoms, as well as groups obtained by removing p hydrogen atoms from hydrocarbon groups and groups in which some of the carbon atoms in a hydrocarbon group have been substituted with a heteroatom such as a nitrogen atom, an oxygen atom, or a sulfur atom. When the p-valent linking group has carbon atoms, it preferably has 1 to 30 carbon atoms, and more preferably has 1 to 20 carbon atoms. The hydrocarbon group may be linear, branched, cyclic, or a combination thereof. The hydrocarbon group may be any of a saturated hydrocarbon group, an unsaturated hydrocarbon group, and an aromatic hydrocarbon group. Examples of aromatic hydrocarbon groups include groups formed by removing a hydrogen atom from an aromatic compound such as a benzene ring, a naphthalene ring, an anthracene ring, a tetracene ring, a pentacene ring, a triphenylene ring, a pyrene ring, a fluorene ring, or an indene ring.

[0044] R in the above general formula (1) 1 ~R 3 are the same or different and represent monovalent substituents. Examples of the monovalent substituent include a fluorine atom; a haloalkyl group such as a fluoromethyl group, a difluoromethyl group, or a trifluoromethyl group; a linear or branched alkyl group having 1 to 20 carbon atoms such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, or a tert-butyl group; a cyclic alkyl group having 5 to 7 carbon atoms such as a cyclopentyl group, a cyclohexyl group, or a cycloheptyl group; a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, an isobutoxy group, a tert-butoxy group, a pentyloxy group, a hexyloxy group, a heptyloxy group, or an oxy group. linear or branched alkoxy groups having 1 to 20 carbon atoms, such as an octyloxy group; a nitro group; a cyano group; an alkylamino group having an alkyl group having 1 to 10 carbon atoms, such as a methylamino group, an ethylamino group, a dimethylamino group, or a diethylamino group; a cyclic amino group, such as a pyrrolidino group, a piperidino group, or a morpholino group; a diarylamino group, such as a diphenylamino group or a carbazolyl group; an acyl group, such as an acetyl group, a propionyl group, or a butyryl group; an alkenyl group having 2 to 30 carbon atoms, such as a styryl group; a halogen atom, such as a fluorine atom, or an alkyl group, alkoxy group, or amino group having 1 to 20 carbon atoms; an aryl group having 5 to 20 carbon atoms which may be substituted with a halogen atom such as a fluorine atom, or an alkyl group, alkoxy group, amino group, or the like having 1 to 20 carbon atoms, containing one or more of a nitrogen atom, sulfur atom, or oxygen atom (heterocyclic group may consist of only one ring, or may be a compound in which a plurality of compounds consisting of only one aromatic heterocycle are directly bonded to each other via one carbon atom, or may be a fused heterocyclic group. Specific examples of heterocyclic groups include a thiophene ring, a furan ring, a phenyl ... Specific examples of aromatic heterocyclic groups include a ring, a pyrrole ring, a benzothiophene ring, a benzofuran ring, an indole ring, a dibenzothiophene ring, a dibenzofuran ring, a carbazole ring, a thiazole ring, a benzothiazole ring, an oxazole ring, a benzoxazole ring, an imidazole ring, a benzimidazole ring, a pyridine ring, a pyrimidine ring, a pyrazine ring, a pyridazine ring, a triazine ring, a quinoline ring, an isoquinoline ring, a quinoxaline ring, a benzothiadiazole ring, and a phenanthridine ring; an ester group, a thioether group, and groups formed by combining these groups.These groups may be substituted with a halogen atom, a hetero element, an alkyl group, an aromatic ring, or the like.

[0045] The compound represented by the above general formula (1) includes a compound having a structure represented by the following general formula (3) which has only one phenanthroline skeleton, and this compound is also suitable as a material for the organic electron injection layer in the present invention.

[0046] [ka]

[0047] (In general formula (3), R 4 , R 5 are the same or different and represent a dialkylamino group or an alkoxy group. 4 , m 5 are the same or different and represent the number 1 or 2. 4 If there are multiple R 4 may be bonded to form a ring structure. 5 The same applies to .)

[0048] R in the above general (3) 4 , R 5 are the same or different and represent a dialkylamino group or an alkoxy group. The dialkylamino group preferably has an alkyl group having 1 to 20 carbon atoms, such as a methyl group or an ethyl group. More preferably, it has an alkyl group having 1 to 10 carbon atoms. The two alkyl groups in the dialkylamino group may have the same or different carbon atoms. Also preferred are amino groups in which two alkyl groups are linked together, such as cyclic amino groups such as piperidino, pyrrolidino, and morpholino groups. The alkoxy group is R 1 ~R 3 is an alkoxy group.

[0049] In addition to compounds having only one phenanthroline skeleton, compounds having multiple phenanthroline skeletons such as those represented by the following formulas (4-1) to (4-4) are also considered to be effective in generating negative charges.

[0050] [ka]

[0051] Furthermore, p in the above general formula (1) represents a number from 1 to 4, and preferably a number from 1 to 3. Specific examples of compounds in which p in general formula (1) is 1 include compounds represented by the following formulas (5-1) to (5-9).

[0052] [ka]

[0053] n in the above general formula (1) 1 represents the number 0 or 1, and the compound represented by the general formula (1) is 1 In one preferred embodiment of the present invention, the compound is a compound in which n in general formula (1) is 0. 1 Specific examples of the compound in which is 0 include the compounds represented by the above formulas (5-1) to (5-6).

[0054] In addition, compounds represented by the following formulae (5-10) to (5-65), which are included in the above general formula (1) and have a similar structure to the above, are also suitable.

[0055] [ka] [ka] [ka] [ka] [ka]

[0056] Furthermore, various compounds having a structure represented by the following formulae (5-66) to (5-68) as a skeletal structure, which has a coordinating nitrogen atom, can also be used as a material for the organic electron injection layer. These compounds include compounds having the structures represented by the following formulae (5-66) to (5-68), as well as compounds having a substituent in the structure represented by the following formulae (5-66) to (5-68). Examples of the substituent include R in the above-mentioned general formula (1). 1 ~R 3 The number of the substituents may be one or more. When there are more than one substituents, the substituents may be bonded to each other to form a ring structure.

[0057] [ka]

[0058] Furthermore, a hexahydropyrimidopyrimidine compound having a structure represented by the following general formula (6) can also be used as a material for the organic electron injection layer.

[0059] [ka]

[0060] (In general formula (6), R 6 represents an aromatic hydrocarbon group, an aromatic heterocyclic group, an aryl alkylene group, a divalent to tetravalent chain or cyclic hydrocarbon group which may have a substituent, a group formed by combining two or more of these groups, or a group formed by combining one or more of these groups with a nitrogen atom. 2 is an integer between 1 and 4.)

[0061] It has been confirmed that a hexahydropyrimidopyrimidine compound having a structure represented by the above general formula (6) can coordinate with the magnesium contained in the cathode when the cathode contains magnesium, preventing reactions at the interface with oxygen or water entering from the outside and improving the atmospheric stability of the device. Furthermore, the dipole generated by interacting with the magnesium contained in the cathode can result in improved electron injection from the cathode.

[0062] R in the above general formula (6) 6 represents an aromatic hydrocarbon group, an aromatic heterocyclic group, an aryl alkylene group, a divalent to tetravalent chain or cyclic hydrocarbon group which may have a substituent, a group formed by combining two or more of these groups, or a group formed by combining one or more of these groups with a nitrogen atom. The aromatic hydrocarbon group and aromatic heterocyclic group preferably have 3 to 30 carbon atoms, more preferably 4 to 24 carbon atoms, and even more preferably 5 to 20 carbon atoms. Examples of aromatic hydrocarbon groups include compounds consisting of only one aromatic ring, such as benzene; compounds in which multiple aromatic rings, such as biphenyl and diphenylbenzene, are directly bonded to each other via one carbon atom; and groups formed by removing 1 to 4 hydrogen atoms from any of the aromatic rings of condensed ring aromatic hydrocarbon compounds, such as naphthalene, anthracene, phenanthrene, and pyrene. Examples of aromatic heterocyclic groups include compounds consisting of only one aromatic heterocycle, such as thiophene, furan, pyrrole, oxazole, oxadiazole, thiazole, thiadiazole, imidazole, pyridine, pyrimidine, pyrazine, and triazine; compounds in which a plurality of compounds consisting of only one aromatic heterocycle are directly bonded to each other via one carbon atom (e.g., bipyridine); and groups obtained by removing 1 to 4 hydrogen atoms from any aromatic heterocycle of fused-ring heteroaromatic hydrocarbon compounds, such as quinoline, quinoxaline, benzothiophene, benzothiazole, benzimidazole, benzoxazole, indole, carbazole, dibenzofuran, dibenzothiophene, acridine, and phenanthroline. Examples of the aryl alkylene group include groups formed by combining the above aromatic hydrocarbon groups with alkylene groups having 1 to 3 carbon atoms. The divalent to tetravalent chain or cyclic hydrocarbon group preferably has 1 to 12 carbon atoms, more preferably 1 to 6 carbon atoms, and even more preferably 1 to 4 carbon atoms. The chain hydrocarbon group may be linear or branched. Also, R 6 may be a group formed by combining two or more of the above aromatic hydrocarbon groups, aromatic heterocyclic groups, aryl alkylene groups, and divalent to tetravalent chain hydrocarbon groups. Furthermore, R 6 may be a group formed by combining one or more of the above aromatic hydrocarbon groups, aromatic heterocyclic groups, aryl alkylene groups, and divalent to tetravalent chain hydrocarbon groups with a nitrogen atom. Examples of such groups include groups formed by removing 1 to 4 hydrogen atoms from trialkylamines such as trimethylamine or triphenylamine.

[0063] The aromatic hydrocarbon group, aromatic heterocyclic group, or arylalkylene group may have one or more monovalent substituents. The monovalent substituent is R in the above general formula (1). 1 ~R 3 Specific examples of the monovalent substituent are the same as those given above.

[0064] n in the above general formula (6) 2 is an integer of 1 to 4, preferably 2 or 3. Specific examples of the hexahydropyrimidopyrimidine compound having the structure represented by the above general formula (6) include compounds represented by the following formulae (7-1) to (7-34).

[0065] [ka] [ka] [ka] [ka] [ka]

[0066] The compound represented by the above general formula (6) can be synthesized by Ullmann coupling reaction, Buchwald-Hartwig amination reaction, nucleophilic substitution reaction, or the like using a halogen compound having iodine, bromine, chlorine, or fluorine and hexahydropyrimidopyrimidine as raw materials, as shown in the following formula (8).

[0067] [ka]

[0068] In addition, other compounds that can be used as ligands can also be used, such as compounds in which the nitrogen atoms of the above-mentioned nitrogen-containing compounds are replaced with oxygen atoms, such as acetylacetonato derivatives.

[0069] The average thickness of the organic electron injection layer is preferably 0.5 to 10 nm, more preferably 1 to 5 nm, and even more preferably 1 to 5 nm. The average thickness of the organic electron injection layer can be measured, for example, by a stylus profilometer or spectroscopic ellipsometry. Alternatively, the organic electron injection layer may be blended with a subsequent electron transport layer.

[0070] "Electron transport material" For the electron transport layer, any material that can be normally used as a material for an electron transport layer may be used, and can be used as needed. Specifically, materials for the electron transport layer include phosphine oxide derivatives such as phenyl-dipyrenylphosphine oxide (POPy2), pyridine derivatives such as tris-1,3,5-(3'-(pyridin-3''-yl)phenyl)benzene (TmPhPyB), quinoline derivatives such as (2-(3-(9-carbazolyl)phenyl)quinoline (mCQ)), pyrimidine derivatives such as 2-phenyl-4,6-bis(3,5-dipyridylphenyl)pyrimidine (BPyPPM), pyrazine derivatives, and benzophenanthroline (BPhen). phenanthroline derivatives such as 2,4-bis(4-biphenyl)-6-(4'-(2-pyridinyl)-4-biphenyl)-[1,3,5]triazine (MPT), triazole derivatives such as 3-phenyl-4-(1'-naphthyl)-5-phenyl-1,2,4-triazole (TAZ), oxazole derivatives, oxadiazole derivatives such as 2-(4-biphenylyl)-5-(4-tert-butylphenyl-1,3,4-oxadiazole) (PBD), 2,2',2''-(1,3,5-benzenetriyl)- Imidazole derivatives such as bis(1-phenyl-1-H-benzimidazole) (TPBI), aromatic carboxylic acid anhydrides such as naphthalene-1,4,5,8-tetracarboxylic dianhydride and 3,4,9,10-perylenetetracarboxylic dianhydride, aromatic imide compounds such as N,N'-dimethyl-3,4,9,10-perylenetetracarboxylic dianhydride, compounds with carbonyl groups such as isoindigo derivatives, 2,5-dihydropyrrolo[3,4-c]pyrrole-1,4-dione derivatives (diketopyrrolopyrroles), and toluxenone, naphtho[1 ,2-c:5,6-c']bis[1,2,5]thiadiazole, 1,2,5-thiadiazole derivatives such as benzo[c][1,2,5]thiadiazole, various metal complexes such as bis[2-(2-hydroxyphenyl)benzothiazolato]zinc (Zn(BTZ)2) and tris(8-hydroxyquinolinato)aluminum (Alq3), organic silane derivatives such as silole derivatives such as 2,5-bis(6'-(2',2''-bipyridyl))-1,1-dimethyl-3,4-diphenylsilole (PyPySPyPy), tris(2,4,Examples of suitable boron-containing compounds include 6-trimethyl-3-(pyridin-3-yl)phenyl)borane (3TPYMB) and boron-containing compounds described in Japanese Patent Application Nos. 2012-228460, 2015-503053, 2015-053872, 2015-081108, and 2015-081109. One or more of these compounds may be used. In addition to the above materials, aromatic hydrocarbon compounds, which are various hydrocarbon compounds having an aromatic ring, compounds having a nitrogen-boron bond, π-electron-rich heteroaromatic compounds containing aromatic rings such as pyrrole rings, furan rings, and thiophene rings, and compounds containing silole rings can also be used. Among these materials for the electron transport layer, it is particularly preferable to use a phosphine oxide derivative such as POPy2, a metal complex such as Alq3, or a pyridine derivative such as TmPhPyB.

[0071] When the material of the electron injection layer of the organic electroluminescent device and the electron transport material are mixed, the electron transport layer may be omitted. Alternatively, a part of these materials may be used as a hole blocking material to form a hole blocking layer. Separately, any material that can be commonly used may be used as the material for the hole blocking layer, and may be used as needed.

[0072] The average thickness of the electron transport layer is not particularly limited, but is preferably 10 to 150 nm, and more preferably 20 to 100 nm. The average thickness of the electron transport layer can be measured by a stylus profilometer or spectroscopic ellipsometry.

[0073] "Emitting layer" The light-emitting layer may be made of any material that is commonly used as a light-emitting layer material, or a mixture of these materials. For example, the light-emitting layer may contain bis[2-(2-benzothiazolyl)phenolato]zinc(II) (Zn(BTZ)2) and tris[1-phenylisoquinoline]iridium(III) (Ir(piq)3). For example, three-coordinate iridium complexes with 2,2'-bipyridine-4,4'-dicarboxylic acid as the ligand, such as factoris(2-phenylpyridine)iridium (Ir(ppy)3), 8-hydroxyquinoline aluminum (Alq3), tris(4-methyl-8-quinolinolato)aluminum(III) (Almq3), 8-hydroxyquinoline zinc (Znq2), (1,10-phenanthroline)-tris-(4,4,4-trifluoro-1-(2-thienyl)-butane-1,3-dionate)europium(III) (Eu(TT A) 3(phen)), various metal complexes such as 2,3,7,8,12,13,17,18-octaethyl-21H,23H-porphine platinum(II); benzene-based compounds such as distyrylbenzene (DSB) and diaminodistyrylbenzene (DADSB); naphthalene-based compounds such as naphthalene and Nile Red; phenanthrene-based compounds such as phenanthrene; chrysene-based compounds such as chrysene and 6-nitrochrysene; perylene, N,N'-bis(2,5-di-t-butylphenyl)-3,4,9,10-perylene perylene compounds such as bis(trimethylsilyl)-dicarboxyimide (BPPC); coronene compounds such as coronene; anthracene compounds such as anthracene and bisstyrylanthracene; pyrene compounds such as pyrene; pyran compounds such as 4-(dicyanomethylene)-2-methyl-6-(para-dimethylaminostyryl)-4H-pyran (DCM); acridine compounds such as acridine; stilbene compounds such as stilbene; thiophene compounds such as 2,5-dibenzoxazolethiophene; benzoxazole benzoxazole compounds such as benzimidazole; benzothiazole compounds such as 2,2'-(para-phenylenedivinylene)-bisbenzothiazole; butadiene compounds such as bistyryl(1,4-diphenyl-1,3-butadiene) and tetraphenylbutadiene; naphthalimide compounds such as naphthalimide; coumarin compounds such as coumarin; perinone compounds such as perinone; oxadiazole compounds such as oxadiazole; aldazine compounds;Examples of suitable compounds include cyclopentadiene compounds such as 1,2,3,4,5-pentaphenyl-1,3-cyclopentadiene (PPCP); quinacridone compounds such as quinacridone and quinacridone red; pyridine compounds such as pyrrolopyridine and thiadiazolopyridine; spiro compounds such as 2,2',7,7'-tetraphenyl-9,9'-spirobifluorene; metal or metal-free phthalocyanine compounds such as phthalocyanine (HPc) and copper phthalocyanine; and boron compound materials described in JP 2009-155325 A, JP 2011-184430 A, and Japanese Patent Application No. 2011-6458 A. The material forming the light-emitting layer may be a low-molecular-weight compound or a high-molecular-weight compound. In the present invention, the low-molecular-weight material means a material that is not a high-molecular-weight material (polymer), and does not necessarily mean an organic compound with a low molecular weight.

[0074] The average thickness of the light-emitting layer is not particularly limited, but is preferably 10 to 150 nm, and more preferably 20 to 100 nm. The average thickness of the light-emitting layer may be measured by a stylus-type step gauge, or may be measured by a quartz crystal film thickness gauge during the formation of the light-emitting layer.

[0075] "Hole transport layer" As the hole transporting organic material used in the hole transport layer, various p-type high molecular weight materials (organic polymers) and various p-type low molecular weight materials can be used alone or in combination. Specific examples of materials for the hole transport layer include N,N'-di(1-naphthyl)-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (α-NPD), N4,N4'-bis(dibenzo[b,d]thiophen-4-yl)-N4,N4'-diphenylbiphenyl-4,4'-diamine (DBTPB), polyarylamine, fluorene-arylamine copolymer, fluorene-bithiophene copolymer, poly(N-vinylcarbazole), polyvinylpyrene, polyvinylanthracene, polythiophene, polyalkylthiophene, polyhexylthiophene, poly(p-phenylenevinylene), polythienylenevinylene, pyrene formaldehyde resin, ethylcarbazole formaldehyde resin, and derivatives thereof. These materials for the hole transport layer 8 can also be used as mixtures with other compounds. An example of a mixture containing polythiophene that can be used as a material for the hole transport layer 8 is poly(3,4-ethylenedioxythiophene / styrenesulfonic acid) (PEDOT / PSS).

[0076] The average thickness of the hole transport layer is not particularly limited, but is preferably 10 to 150 nm, and more preferably 20 to 100 nm. The average thickness of the hole transport layer can be measured, for example, by a stylus profilometer or spectroscopic ellipsometry.

[0077] "Hole injection layer" The hole injection layer may be made of an inorganic material or an organic material. Inorganic materials are more stable than organic materials, and therefore tend to have higher resistance to oxygen and water than organic materials.

[0078] The inorganic material is not particularly limited, but for example, one or more metal oxides such as vanadium oxide (V2O5), molybdenum oxide (MoO3), and ruthenium oxide (RuO2) can be used.

[0079] Examples of organic materials that can be used include low molecular weight materials such as dipyrazino[2,3-f:2',3'-h]quinoxaline-2,3,6,7,10,11-hexacarbonitrile (HAT-CN) and 2,3,5,6-tetrafluoro-7,7,8,8-tetracyano-quinodimethane (F4-TCNQ), as well as poly(3,4-ethylenedioxythiophene) / polystyrene sulfonate (PEDOT:PSS).

[0080] The average thickness of the hole injection layer is not particularly limited, but is preferably 1 to 1000 nm, and more preferably 5 to 50 nm. The average thickness of the hole injection layer can be measured during film formation using a quartz crystal film thickness gauge, a stylus step gauge, or spectroscopic ellipsometry.

[0081] "anode" Examples of materials used for the anode include ITO, IZO, Au, Pt, Cu, Ag, Al, and alloys containing these. Among these, it is preferable to use ITO, IZO, Au, or Al as the material for the anode 10.

[0082] In an organic electroluminescent device with an inverted structure, the anode is the upper electrode, and since it is difficult to provide a conductive layer to support conduction, the anode itself must be responsible for conduction. Therefore, the average thickness of the anode is preferably 200 nm or more. With such a thickness, the electrical resistance of the electrode can be reduced, the thin-film light-emitting device of the present invention can have better light-emitting properties, and manufacturing variations can be reduced. The average thickness of the anode is more preferably 300 nm or more, and even more preferably 400 nm or more. Furthermore, from the viewpoint of reducing thermal damage to the device, the average thickness of the anode is preferably 300 nm or less. The average thickness of the anode can be measured during the deposition of the anode using a quartz crystal film thickness meter.

[0083] "Sealing" The organic electroluminescent device of the present invention may be sealed, if necessary. For example, the organic electroluminescent element may be sealed with a sealed container having a recessed space for accommodating the organic electroluminescent element and an adhesive for bonding the edge of the sealed container to the substrate. Alternatively, the organic electroluminescent element may be housed in a sealed container and sealed by filling it with a sealant made of an ultraviolet (UV) curable resin or the like. Alternatively, the organic electroluminescent element may be sealed with a sealing member made of a plate member placed on the anode and a frame member placed along the edge of the plate member facing the anode, and an adhesive for bonding between the plate member and the frame member and between the frame member and the substrate.

[0084] When the organic electroluminescent element of the present invention is sealed, the distance from the edge of the sealing container or sealing member to the organic electroluminescent element is preferably 0.1 to 10 mm. If the distance from the edge of the sealing container or sealing member to the organic electroluminescent element is within this range, the sealing can be sufficiently maintained even when the element is bent or twisted. The distance is more preferably 0.1 to 5 mm, and even more preferably 0.1 to 2 mm. The distance from the end of the sealing container or sealing member to the organic electroluminescent element referred to here can also be rephrased as the width of the portion where the sealing containers or sealing members above and below the organic electroluminescent element are in direct contact with each other via an adhesive, ultraviolet curable resin, or the like.

[0085] When the organic electroluminescent element is sealed using a sealing container or a sealing member, a moisture-absorbing desiccant may be placed inside the sealing container or the sealing member. Furthermore, a moisture-absorbing material may be used as the sealing container or the sealing member. Furthermore, a space may be formed inside the sealed sealing container or the sealing member.

[0086] The material of the sealing container or sealing member used to seal the organic electroluminescent element can be a resin material, etc. Examples of the resin material used for the sealing container or sealing member include the same materials as those used for the substrate.

[0087] In the organic electroluminescent device according to the first preferred embodiment of the present invention, when ITO is used as the cathode, the metal electron injection layer is the above-mentioned metal thin film having a work function of 4.0 eV or more, and the organic electron injection layer is formed using an organic material having the coordination ability represented by the above-mentioned general formula (1), superior durability can be obtained compared to, for example, a case in which an alkali metal, which is a material that is unstable in the atmosphere, is used as the electron injection layer. In the organic electroluminescent device according to the second preferred embodiment of the present invention, when the electron injection layer is formed using an organic material having a coordinating ability represented by the general formula (1), excellent durability can be obtained compared to a device in which the electron injection layer is formed using only an alkali metal, which is an unstable material in the atmosphere. -4 ~10 -3 Order (g / m 2 / day), deterioration of the organic electroluminescent device can be sufficiently suppressed. -3 Order (g / m 2 It is possible to use a resin material with a thermal conductivity of about 1 / day or less, and an organic electroluminescent device with excellent flexibility can be realized.

[0088] In the organic electroluminescent device of the present invention, the method for forming a layer made of an organic compound is not particularly limited, and various methods can be used as appropriate depending on the characteristics of the material. When a solution can be formed and applied, various coating methods such as spin coating, casting, microgravure coating, gravure coating, bar coating, roll coating, wire bar coating, slit coating, dip coating, spray coating, screen printing, flexographic printing, offset printing, and inkjet printing can be used to form a film. Of these, spin coating and slit coating are preferred because they make it easier to control the film thickness. When no coating is required or when the solvent solubility is low, suitable examples include vacuum deposition and ESDUS (Evaporative Spray Deposition from Ultra-dilute Solution) methods.

[0089] When a layer made of the organic compound is formed by applying an organic compound solution, examples of the solvent used to dissolve the organic compound include inorganic solvents such as nitric acid, sulfuric acid, ammonia, hydrogen peroxide, water, carbon disulfide, carbon tetrachloride, and ethylene carbonate; ketone-based solvents such as methyl ethyl ketone (MEK), acetone, diethyl ketone, methyl isobutyl ketone (MIBK), methyl isopropyl ketone (MIPK), and cyclohexanone; alcohol-based solvents such as methanol, ethanol, isopropanol, ethylene glycol, diethylene glycol (DEG), and glycerin; and ether-based solvents such as diethyl ether, diisopropyl ether, 1,2-dimethoxyethane (DME), 1,4-dioxane, tetrahydrofuran (THF), tetrahydropyran (THP), anisole, diethylene glycol dimethyl ether (diglyme), and diethylene glycol ethyl ether (carbitol). aromatic hydrocarbon solvents such as toluene, xylene, benzene, etc.; aromatic heterocyclic compound solvents such as pyridine, pyrazine, furan, pyrrole, thiophene, methylpyrrolidone, etc.; amide solvents such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMA), etc.; halogen compound solvents such as chlorobenzene, dichloromethane, chloroform, 1,2-dichloroethane, etc.; ester solvents such as ethyl acetate, methyl acetate, ethyl formate, etc.; sulfur compound solvents such as dimethyl sulfoxide (DMSO), sulfolane, etc.; nitrile solvents such as acetonitrile, propionitrile, acrylonitrile, etc.;Among these, non-polar solvents are preferred as the solvent, and examples thereof include aromatic hydrocarbon solvents such as xylene, toluene, cyclohexylbenzene, dihydrobenzofuran, trimethylbenzene, and tetramethylbenzene; aromatic heterocyclic compound solvents such as pyridine, pyrazine, furan, pyrrole, thiophene, and methylpyrrolidone; and aliphatic hydrocarbon solvents such as hexane, pentane, heptane, and cyclohexane, and these can be used alone or in combination.

[0090] Among the layers of the organic electroluminescent device, layers made of inorganic materials can be formed by sputtering, vacuum deposition, sol-gel, spray pyrolysis (SPD), atomic layer deposition (ALD), vapor-phase deposition, liquid-phase deposition, etc. Metal foil bonding can also be used to form the anode and cathode. These methods are preferably selected depending on the properties of the material of each layer, and different fabrication methods may be used for each layer. When the hole injection layer is a layer made of an inorganic material, it is more preferable to form it using a vapor-phase deposition method. Vapor-phase deposition allows the hole injection layer to be formed cleanly and in good contact with the anode without damaging the surface of the organic compound layer, resulting in a more pronounced effect of having the hole injection layer.

[0091] The thin-film light-emitting element of the present invention has an average thickness of 0.2 mm or less, and has a long and slender shape in which the ratio of the length in the longitudinal direction of the element to the longest length in the direction perpendicular to the longitudinal direction is 10 or more, and is an element with excellent flexibility, so it can be used as a string-shaped light source. A string-shaped light source using such a thin-film light-emitting element of the present invention also constitutes one aspect of the present invention. [Example]

[0092] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" means "parts by weight" and "%" means "% by mass."

[0093] (Synthesis Example 1) The compound represented by the following formula (9) was synthesized by the method shown below.

[0094] [ka]

[0095] In a 100 mL round-bottom flask, a mixture of 4,7-dichloro-1,10-phenanthroline (3.00 g) and pyrrolidine (19.5 mL) was heated to reflux in an oil bath at 100 °C for 1 hour. The mixture was returned to room temperature and concentrated under reduced pressure. Water was added, and the mixture was sonicated. The precipitated solid was collected by filtration. The resulting solid was dried under reduced pressure and then dissolved in methanol (100 mL). Activated carbon was added to the mixture, and the mixture was stirred at room temperature for 1 hour. The insoluble matter was then filtered off. The filtrate was concentrated under reduced pressure, and the resulting solid was recrystallized from methanol (9 mL). The resulting solid was washed with a small amount of methanol and dried under reduced pressure to obtain the compound represented by formula (9) above (1.69 g, 44%) as a white solid.

[0096] Example 1 [Process 1] Barrier film manufactured by Oike Kogyo (PT7 / 25GT3, thickness: 25 μm, WVTR: 4 × 10 -3 g / m 2 A resist material was applied onto the surface of the glass substrate (.times. / day, Young's modulus: 5 GPa) to form a film, and then a zinc oxide film of 24 nm was formed using a sputtering device to form a metal oxide layer 4. [Step 2] Next, to form a layer containing silver and zinc in a volume ratio of 10:1 and having a total thickness of 14.85 nm as the cathode 3 and metal electron injection layer 5, the substrate that has been processed in [Step 1] is introduced into a vacuum chamber, and 5 × 10 -5 The pressure was reduced to 0.05 Pa or less, and a film was formed by vacuum deposition. [Step 3] Next, the material of the above formula (9), which is a material for organic electron injection layers, was laminated by vacuum deposition to form an organic electron injection layer 6 with a thickness of 3 nm, an electron transporting material, KHLHEI-02 manufactured by Chemipro Chemical Co., Ltd., with a thickness of 15 nm, an electron blocking layer 12, KHLHS-04 manufactured by Chemipro Chemical Co., Ltd., with a thickness of 15 nm, an emitting layer 8, KHLHS-03, KHLHS-04, and KHLDG-01 manufactured by Chemipro Chemical Co., Ltd., with a thickness of 35 nm, and a hole transporting layer 9, KHLHS-03 manufactured by Chemipro Chemical Co., Ltd., with a thickness of 25 nm. [Step 4] Next, the hole injection layer 10 was formed on the hole transport layer 9. Here, molybdenum oxide was formed to a thickness of 10 nm by vacuum deposition, which is a vapor phase film formation method. [Step 5] Next, as the final step, an anode 11 was formed on the hole injection layer 10. Here, an aluminum film was formed by vacuum deposition to a thickness of 400 nm. Furthermore, a barrier film (25 μm thick, WVTR: 4×10) manufactured by Oike Kogyo Co., Ltd. was formed on the anode. -3 g / m 2 Sealing was carried out at 100°C / day. By following the above steps [Step 1] to [Step 5], a film organic electroluminescent device with the configuration shown in Figure 11 was fabricated. By adjusting the shape of the electrodes, etc., a film element with a length of 150 mm, width of 5.5 mm, and thickness of approximately 98 μm was created. The Young's modulus follows the rule of mixture, and since most of the volume fraction is made up of the film substrate, it can be approximated and considered to be equivalent to the Young's modulus of the barrier film. The light-emitting state is shown in Figure 17. It was successfully wrapped around a glass rod with an outer diameter of 3 mm. The pitch was 1 cm, and it was confirmed that the degradation behavior in this state was equivalent to that of a normal-shaped element with the same configuration. [Explanation of symbols]

[0097] 1, 21: organic electroluminescent device, 2: substrate, 3: cathode, 4: metal oxide layer, 5: metal electron injection layer, 6: organic electron injection layer, 7: electron transport layer, 8: light-emitting layer, 9: hole transport layer, 10: hole injection layer, 11: anode, 12: hole blocking layer

Claims

1. a thin-film light-emitting element comprising a film substrate, a structure in which a plurality of layers are laminated between an anode and a cathode, one or more organic compound layers are disposed between the anode and the cathode, the entire laminate structure including the organic compound layers being formed directly on the film substrate, the surface of the laminate structure opposite to the film substrate being sealed with a film, the element having a Young's modulus of 10,000 MPa or less, an average thickness of 0.2 mm or less, and a ratio of the length of the element in the longitudinal direction to the longest length direction perpendicular to the longitudinal direction of 10 or more.

2. 2. The thin-film light-emitting element according to claim 1, wherein the thin-film light-emitting element has electrode lead-out portions at both ends in the longitudinal direction of the element.

3. 3. The thin-film light-emitting element according to claim 1, wherein the thin-film light-emitting element is an organic electroluminescent element having a structure in which a plurality of layers are stacked between an anode and a cathode, and further having one or more organic compound layers between the anode and the cathode, and further having the cathode on the substrate side.

4. The thin-film light-emitting device according to claim 3, wherein the average thickness of the upper electrode of the organic electroluminescent device is 20 nm or more.

5. A strip-shaped light source comprising the thin-film light-emitting element according to any one of claims 1 to 4.

6. A light source system that uses a plurality of strip light sources according to claim 5 to achieve the effect of a surface light source.

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