Display device and method for manufacturing display device

Abstract

This display device (1) comprises: a first light-emitting element (5R) that is provided, between a first anode (22) and a second cathode (25), with a first light-emitting layer (24EMR) and a first functional layer (24ETR) that contacts the first light-emitting layer (24EMR); and a second light-emitting element (5G) that is provided, between a second anode (22) and the second cathode (25), with a second light-emitting layer (24EMG) and a second functional layer (24ETG) that contacts the second light-emitting layer (24EMG). The first and second light-emitting layers (24EMR-24EMG) emit light in colors different from each other, and the first functional layer (24ETR) is doped with a first element of either group 16 or group 17.

Description

Display device, and method for manufacturing a display device.

[0001] This disclosure relates to a display device and a method for manufacturing a display device.

[0002] For example, Patent Document 1 describes an organic EL panel comprising: a transistor array substrate on which a plurality of drive units are arranged; an interlayer insulating film formed on the transistor array substrate, with contact holes formed in a portion of the region corresponding to the drive units; a plurality of pixel electrodes electrically connected to the drive units via the contact holes; an organic EL layer formed on the region on which the pixel electrodes are arranged; and a common electrode formed on the organic EL layer. In the organic EL panel described in Patent Document 1, the electrical resistivity of the region corresponding to each contact hole of the interlayer insulating film and the region between adjacent pixel electrodes is higher than that of other regions in the organic EL layer.

[0003] International Publication No. 2013 / 011599

[0004] The display device such as the organic EL panel described in Patent Document 1 provides a solution to the problem caused by the in-plane distribution of conductivity in the charge transport layer. However, the display device such as the organic EL panel described in Patent Document 1 has the problem that the electron injection barriers of the light-emitting elements that emit light in each color are different. Furthermore, the organic EL panel described in Patent Document 1 does not disclose any problems related to display devices including quantum dots.

[0005] This disclosure has been made in view of the above-mentioned problems, and its purpose is to provide a display device and related technologies in which the difference in electron injection barriers of light-emitting elements that emit light in each color is reduced.

[0006] A display device according to one aspect of the present disclosure is a display device comprising a plurality of light-emitting elements in a display area provided on a substrate, comprising: a first light-emitting element comprising a first light-emitting layer and a first functional layer in contact with the first light-emitting layer between a first anode and a first cathode; and a second light-emitting element comprising a second light-emitting layer and a second functional layer in contact with the second light-emitting layer between a second anode and a second cathode, wherein the first and second light-emitting layers emit light in different colors from each other, and a first element consisting of either group 16 or group 17 is added to the first functional layer.

[0007] Furthermore, a method for manufacturing a display device according to one aspect of the present disclosure is a method for manufacturing a display device comprising a plurality of light-emitting elements that emit light in two or more colors in a display area provided on a substrate, comprising the steps of: forming a first light-emitting layer by coating a first light-emitting layer composition containing a first light-emitting layer material onto a first anode; forming a second light-emitting layer by coating a second light-emitting layer composition containing a second light-emitting layer material onto a second anode; coating a first composition containing a first element from either group 16 or group 17 onto the first light-emitting layer, and coating a second composition containing a second element from either group 16 or group 17 onto the second light-emitting layer; forming a functional layer that contacts the first and second light-emitting layers by coating a functional layer composition containing a functional layer material onto the first and second light-emitting layers; and forming first and second cathodes on the functional layer. The elements contained in the first and second light-emitting layers are moved to form a first functional layer containing the first element and a second functional layer containing the second element.

[0008] A method for manufacturing a display device according to one aspect of the present disclosure is a method for manufacturing a display device comprising a plurality of light-emitting elements that emit light in two or more colors in a display area provided on a substrate, comprising the steps of: forming a first light-emitting layer by coating a first light-emitting layer composition comprising a first light-emitting layer material and a first element selected from either Group 16 or Group 17 onto a first anode; forming a second light-emitting layer by coating a second light-emitting layer composition comprising a second light-emitting layer material and a second element selected from either Group 16 or Group 17 onto a second anode; forming a functional layer that contacts the first and second light-emitting layers by coating a functional layer composition comprising a functional layer material onto the first and second light-emitting layers; and forming first and second cathodes on the functional layer. The first and second elements contained in the first and second light-emitting layers are moved to the functional layer to form a first functional layer containing the first element and a second functional layer containing the second element.

[0009] According to this disclosure, it is possible to provide a display device and related technologies in which the difference in electron injection barriers of light-emitting elements that emit light in each color is reduced.

[0010] This is a cross-sectional view showing the schematic configuration of a display device 1 according to one embodiment. This is a cross-sectional view showing the schematic configuration of a display device 1 according to one embodiment. This is a plan view showing the schematic configuration of the light-emitting elements 5R, 5G, and 5B provided in a display device 1 according to one embodiment. This is a diagram showing an example of the LUMO energy levels of each layer in the functional layers 24R, 24G, and 24B provided in the light-emitting elements 5R, 5G, and 5B provided in a display device 1 according to one embodiment. This is a diagram illustrating the schematic of the manufacturing method of a display device 1 according to one embodiment up to the step of forming the light-emitting layer. This is a diagram illustrating the schematic of the manufacturing method of a display device 1 according to one embodiment up to the step of transferring elements from the light-emitting layer to the functional layer. This is a diagram illustrating the schematic of the manufacturing method of a display device according to one embodiment (second embodiment). This is a diagram illustrating the schematic of the manufacturing method of a display device according to one embodiment (third embodiment). This is a diagram illustrating the schematic of the manufacturing method of a display device according to one embodiment (fourth embodiment). This is a diagram illustrating the schematic of the manufacturing method of a display device according to one embodiment (fifth embodiment). This is a diagram illustrating the schematic of the light-emitting elements provided in a display device according to one modified example (second modified example).

[0011] The embodiments of this disclosure are described below. For the sake of convenience, in the following description, components having the same function as those described in a particular embodiment may be denoted by the same reference numerals, and their descriptions may be omitted.

[0012] <Display Device 1> A display device 1 according to one embodiment of the present disclosure will be described using Figures 1 to 7. Figure 1 is a plan view showing a schematic configuration of the display device 1 according to one embodiment.

[0013] As shown in Figure 1, the display device 1 comprises a frame area NDA and a display area DA. The display area DA of the display device 1 is provided with a plurality of pixels PIX, and each pixel PIX includes a red subpixel RSP, a green subpixel GSP, and a blue subpixel BSP. In this embodiment, the case in which one pixel PIX is composed of a red subpixel RSP, a green subpixel GSP, and a blue subpixel BSP is described as an example, but it is not limited to this. For example, one pixel PIX may include subpixels of other colors in addition to the red subpixel RSP, green subpixel GSP, and blue subpixel BSP.

[0014] Figure 2 is a cross-sectional view showing the schematic configuration of the display area DA of the display device 1.

[0015] As shown in Figure 2, in the display area DA of the display device 1, a barrier layer 3, a thin-film transistor layer 4 including a transistor TR, an element-emitting element 5R, an element-emitting element 5G, an element-emitting element 5B and a bank 23, a sealing layer 6, and a functional film 39 are provided on the substrate 12 in this order from the substrate 12 side.

[0016] As shown in Figure 2, the red subpixel RSP provided in the display area DA of the display device 1 includes a light-emitting element 5R (red light-emitting element) that emits red light, the green subpixel GSP provided in the display area DA of the display device 1 includes a light-emitting element 5G (green light-emitting element) that emits green light, and the blue subpixel BSP provided in the display area DA of the display device 1 includes a light-emitting element 5B (blue light-emitting element) that emits blue light. As shown in Figure 3, each of the light-emitting elements 5R, 5G, and 5B is provided in the light-emitting area HR surrounded by the non-light-emitting area NHR in the display area DA. In Figure 2, to show the schematic configuration of the display area DA of the display device 1, a functional layer 24R containing a red light-emitting layer, a functional layer 24G containing a green light-emitting layer, and a functional layer 24B containing a blue light-emitting layer are schematically shown to be provided for each subpixel of each color. The hole transport layer 24HT and electron transport layer 24ET of the functional layer 24R are provided as common layers (one layer) for the red subpixel RSP, green subpixel GSP, and blue subpixel BSP, respectively, although this is not shown in the figure. In reality, the light-emitting layer 24EM provided on the light-emitting element 5R shown in Figure 3Ｒ Like the functional layer 24R which includes the light-emitting layer 24EM Ｒ Excluding the above, the hole transport layer 24HT and the electron transport layer 24ET are formed over the entire surface of the display area DA and, like the cathode 25, are provided as common layers for each subpixel of each color.

[0017] [Light-emitting element] As shown in Figure 3, the light-emitting element 5R includes an anode 22 (first anode), a functional layer 24R, and a cathode 25 (first cathode). Here, the functional layer 24R includes a hole transport layer (another functional layer) 24HT and a light-emitting layer (first light-emitting layer) 24EM that emits red light. Ｒ and the electron transport layer (first functional layer) 24ET Ｒ The light-emitting element 5G includes an anode 22 (second anode), a functional layer 24G, and a cathode 25 (second cathode), where the functional layer 24G includes a hole transport layer 24HT and a light-emitting layer (second light-emitting layer) 24EM that emits green light. Ｇ and the electron transport layer (second functional layer) 24ET Ｇ The device also includes the following: The light-emitting element 5B includes an anode 22 (third anode), a functional layer 24B, and a cathode 25 (third cathode), where the functional layer 24B includes a hole transport layer 24HT and a light-emitting layer (third light-emitting layer) 24EM that emits blue light. Ｂ and the electron transport layer (third functional layer) 24ET Ｂ The device comprises the following. The first anode of the light-emitting element 5R, the second anode of the light-emitting element 5G, and the third anode of the light-emitting element 5B may be formed as, for example, pixel electrodes. The first cathode of the light-emitting element 5R, the second cathode of the light-emitting element 5G, and the third cathode of the light-emitting element 5B may be formed integrally as, for example, a common electrode. In the following description, the configuration of the red light-emitting element may be designated as "first," the configuration of the green light-emitting element as "second," and the configuration of the blue light-emitting element as "third," but this is just an example and does not specify the relationship between "first," "second," and "third" and the light-emitting color of the light-emitting element.

[0018] Incidentally, as shown in FIG. 3, among the electron transport layers 24ET formed on the entire surface of the display region DA, in each of the light-emitting regions NH surrounded by the non-light-emitting regions NHR, the light-emitting layers 24EM which are the first to third light-emitting layers Ｒ · 24EM Ｇ · 24EM Ｂ are formed such that they correspond to any one of the first to third electron transport layers, which are the electron transport layers ET Ｒ · 24ET Ｇ · 24ET Ｂ are formed.

[0019] (Anode and Cathode) Depending on whether the light-emitting elements 5R·5G·5B are top emission type or bottom emission type, the electrode materials of the anode 22 and the cathode 25 may be selected for the light-emitting elements 5R·5G·5B. For example, when the light-emitting elements 5R·5G·5B are top emission type with a sequential stacking structure, the anode 22 may be formed of an electrode material that reflects visible light, and the cathode 25 may be formed of an electrode material that transmits visible light. Conversely, when the light-emitting elements are bottom emission type, the cathode 25 may be formed on the substrate of an electrode material that transmits visible light, and the anode may be formed of an electrode material that reflects visible light. Hereinafter, the case where the light-emitting elements 5R·5G·5B have a sequential stacking structure will be described. However, the light-emitting elements may have an inverted stacking structure, in which the cathode, the electron transport layer as a functional layer, the light-emitting layer, the hole transport layer as another functional layer, and the anode are formed in this order on the substrate.

[0020] The electrode material that reflects visible light for forming the anode 22 and / or the cathode 25 is not particularly limited as long as it can reflect visible light and has conductivity. For example, metal materials such as Al, Cu, Au, Mg, Li, Ag, alloys of the metal materials, laminates of the metal materials and transparent metal oxides (e.g., indium tin oxide, indium zinc oxide, indium gallium zinc oxide, etc.), laminates of the alloys and the transparent metal oxides, etc. can be mentioned.

[0021] On the other hand, the electrode material that transmits visible light for forming the anode 22 and / or cathode 25 is not particularly limited as long as it can transmit visible light and is conductive, but examples include a transparent metal oxide (e.g., indium tin oxide, indium zinc oxide, indium gallium zinc oxide, etc.), a thin film made of a metallic material such as Al or Ag, or a nanowire made of a metallic material such as Al or Ag.

[0022] [Hole Transport Layer] The light-emitting elements 5R, 5G, and 5B consist of an anode 22 and a light-emitting layer 24EM. Ｒ ・24EM Ｇ ・24EM Ｂ Between them, the light-emitting layer 24EM Ｒ ・24EM Ｇ ・24EM Ｂ Each of these is equipped with a hole transport layer (another functional layer) 24HT that is in contact with the anode 22 to the light-emitting layer 24EM. Ｒ ・24EM Ｇ ・24EM Ｂ It transports holes toward the hole. The hole transport material (which is also the material for the functional layer) contained in the hole transport layer 24HT includes, for example, NiO, CuI, Cu ２ O, CoO, Cr ２ O ３ CuAlS ２ Examples of nanoparticles include the following.

[0023] Although not shown in the diagram, the hole transport layer may be composed of multiple layers from the viewpoint of increasing the efficiency of hole injection. When the light-emitting element has multiple hole transport layers, one of the hole transport layers may be called the hole injection layer. When a hole injection layer is provided as the hole transport layer, the hole injection layer is formed on the anode 22, and the hole transport layer may be formed on the hole injection layer. Examples of hole-injecting materials include poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-4-sec-butylphenyl))diphenylamine)] (abbreviated as "TFB"), poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)-benzidine] (abbreviated as "p-TPD"), polyvinylcarbazole (abbreviated as "PVK"), etc. Only one type of these hole-injecting material may be used, or two or more types may be mixed and used as appropriate. In addition, a hole-injection layer (not shown) may be formed. Examples include a composite of poly(3,4-ethylenedioxythiophene) (PEDOT) and polystyrene sulfonic acid (PSS) (abbreviated as "PEDOT:PSS"), NiO (nickel oxide), CuSCN (copper thiocyanate), etc. These materials may be used individually or mixed in combination of two or more as appropriate.

[0024] [Emitting layer] Emitting layer 24EM Ｒ ・24EM Ｇ ・24EM Ｂ The device emits light due to the recombination of holes transported from the anode 22 and electrons transported from the cathode 25. In this embodiment, the light-emitting layer 24EM Ｒ ・24EM Ｇ ・24EM Ｂ This is a quantum dot light-emitting layer that contains one of each color of quantum dots (QD: semiconductor nanoparticles) as the light-emitting material.

[0025] The first light-emitting layer is the light-emitting layer 24EM Ｒ This is the second light-emitting layer, light-emitting layer 24EM Ｇ The third light-emitting layer, light-emitting layer 24EM, emits light with a longer wavelength than the first layer. Ｂ This is the second light-emitting layer, light-emitting layer 24EM ＧIt emits light with a shorter wavelength than [the other element]. More specifically, for example, the 24EM light-emitting layer... Ｒ The light emitted can have a emission center wavelength in the wavelength band between 600 nm and 780 nm, and can be red light. Also, the light-emitting layer 24EM Ｇ The light emitted can have a emission center wavelength in the wavelength band between 500 nm and 600 nm, and can be green light. Furthermore, the light-emitting layer 24EM Ｂ The light emitted may have a emission center wavelength in the wavelength band between 400 nm and 500 nm, and may be blue light. In one embodiment, the multiple types of quantum dots are a combination of red quantum dots, green quantum dots, and blue quantum dots, but the combination does not necessarily have to be this one.

[0026] Light-emitting layer 24EM Ｒ ・24EM Ｇ ・24EM Ｂ The quantum dots (QDs) contained in may have, for example, a core structure, a core / shell structure, a core / shell / shell structure, or a shell structure with continuously changing core / ratio. The shell may cover a part of the core, but it is preferable that it completely covers the core. The core material of the quantum dots (QDs) may be, for example, crystals of II-VI semiconductors such as MgS, MgSe, MgTe, CaS, CaSe, CaTe, BaS, BaSe, BaTe, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, PbS, PbSe, HgS, HgSe, HgTe, crystals of III-V semiconductors such as GaAs, GaP, InN, InAs, InP, InSb, Ga ３ S ２ Ga ２ See ３ In ２ S ３ In ２ See ３ Crystals of III-VI semiconductors such as CuInGaS, AgInGaS, CuInGaS, AgInGaZnS, CuInGaSe, AgInGaSe, etc., crystals of I-III-VI semiconductors such as C, Si, etc., crystals of IV semiconductors such as CsPbI ３ , CsPbBr ３ , CsPbCl ３The shell material can be composed of semiconductor crystals with a perovskite structure, such as those shown above. The shell material is selected from the same group of materials as the core material, and it is preferable that the shell material has a lattice constant close to that of the core material and a larger band gap than the core material. As a quantum dot (QD), it is preferable, but not limited to, a core / shell structure in which the core material is composed of InP and the shell material is composed of a metal sulfide (e.g., zinc sulfide (ZnS)). For example, ZnSe or ZnSeTe may be used as the core material, and these are particularly preferred for use in blue subpixels.

[0027] A quantum dot (QD) refers to a dot with a maximum width of 100 nm or less. The shape of a quantum dot (QD) is not particularly restricted and is not limited to a spherical three-dimensional shape (circular cross-sectional shape), as long as it satisfies the above maximum width. For example, it may have a polygonal cross-sectional shape, a rod-shaped three-dimensional shape, a branch-shaped three-dimensional shape, a three-dimensional shape with irregularities on the surface, or a combination thereof.

[0028] Quantum dots (QDs), which are luminescent materials, often contain organic ligands. Examples of such organic ligands include oleylamine, octanthiol, dodecanethiol, tributylphosphine oxide, trioctylphosphine, and oleic acid. Among these, octanthiol, dodecanethiol, trioctylphosphine, and oleic acid are more preferred as organic ligands. Furthermore, quantum dots (QDs) may also contain halogen ions as ligands, where chloride ions are preferred. Among the ligands, those having coordinating groups such as thiol groups and carboxylic acid groups have elements belonging to Group 17 or Group 18 in their molecular structure, and these elements, as elements included in the organic ligand, can move to the electron transport layer described later. Furthermore, when the ligand is a halogen ion, the halogen ion is an element belonging to Group 17.

[0029] Light-emitting layer 24EM Ｒ ・24EM Ｇ ・24EM ＢIt is preferable that it comprises a matrix derived from a metal complex. In this application, "metal complex" may refer to a compound having a structure in which a metalloid and a nonmetal are bonded, instead of a structure in which a metal and a nonmetal are bonded. Luminescent layer 24EM Ｒ ・24EM Ｇ ・24EM Ｂ If the device includes a matrix, the matrix may be an inorganic insulator or an inorganic semiconductor. The matrix may be, for example, a metalloid oxide such as silicon oxide, or ZnS (zinc sulfide), ZnTeS, or ZnMgS ２ MgS, Ga ２ S ３ , ZnGa ２ S ４ MgGa ２ S ４ The metal sulfide may also be used. The matrix is, for example, the light-emitting layer 24EM Ｒ ・24EM Ｇ ・24EM Ｂ At any position in the film thickness direction, 1000 nm in the plane direction perpendicular to the film thickness direction. ２ It may have the above area. Also, the light-emitting layer 24EM Ｒ ・24EM Ｇ ・24EM Ｂ The average film thickness may be between 10 nm and 100 nm, and the light-emitting layer 24EM Ｒ ・24EM Ｇ ・24EM Ｂ The maximum film thickness may be less than or equal to twice the minimum film thickness.

[0030] Light-emitting layer 24EM Ｒ ・24EM Ｇ ・24EM Ｂ If the matrix is ​​derived from a metal complex, the luminescent layer 24EM Ｒ ・24EM Ｇ ・24EM Ｂ The composition for the light-emitting layer to form the light-emitting layer 24EM includes a metal complex as a matrix precursor and may also include a halogen source. Ｒ ・24EM Ｇ ・24EM Ｂmay contain an element derived from the metal complex and / or the halogen source. Here, the element may be an element belonging to Group 16 or Group 17 of the periodic table, and the light-emitting layer 24EM Ｒ contains a first element, and the light-emitting layer 24EM Ｇ contains a second element, and the two light-emitting layers 24EM Ｂ may contain a third element. Each of the first, second, and third elements may be the same element or may be different from each other.

[0031] The light-emitting layer 24EM Ｒ ・24EM Ｇ ・ 24EM Ｂ When the light-emitting layer 24EM contains an element of Group 16, the element may be sulfur (S) derived from a metal complex having xanthic acid, thiocarboxylic acid, thiourea, etc. having an alkyl group as a ligand. More specifically, the ligands of the metal complex include, for example, xanthic acids such as methylxanthic acid, ethylxanthic acid, n-propylxanthic acid, and i-propylxanthic acid, thiocarboxylic acids such as methylthiocarboxylic acid, ethylthiocarboxylic acid, n-propylthiocarboxylic acid, and i-propylthiocarboxylic acid, and N-methylthiourea, 1,3-dimethylthiourea, N,N'-dimethylthiourea, tetramethylthiourea, or thioacetamide.

[0032] Also, when the light-emitting layer 24EM Ｒ ・ 24EM Ｇ ・ 24EM Ｂ contains oxygen (O) as an element of Group 16, the oxygen is oxygen derived from a hydroxyl group and an alkoxy group such as a methoxy group. These hydroxyl groups and alkoxy groups may be groups possessed by silicon oxide for forming a silicon oxide semiconductor, and the silicon oxide may be selected from, for example, diphenylsilanediol, 3-mercaptopropyltrimethoxysilane (MPS), or 3-mercaptopropyltriethoxysilane. In addition, the silicon oxide may contain, for example, tetramethyl orthosilicate (TMOS), tetraethyl orthosilicate (TEOS), trimethoxyphenylsilane, etc.

[0033] Incidentally, from the perspective of forming a metal sulfide semiconductor, the metal of the metal complex is preferably zinc (Zn), cadmium (Cd), lead (Pb), mercury (Hg), copper (Cu), indium (In), gallium (Ga), tin (Sn), potassium (K), magnesium (Mg), calcium (Ca), or barium (Ba). More preferably, it is tin (Sn), magnesium (Mg), or zinc (Zn), and even more preferably, it is zinc (Zn).

[0034] Further, the light-emitting layer 24EM Ｒ ・24EM Ｇ ・24EM Ｂ In the case where the light-emitting layer 24EM contains an element of Group 17, the element contains a halogen source selected from chlorine (Cl), bromine (Br), iodine (I), and fluorine (F), separately from the halogen ions that coordinate to the above-described quantum dots. When the halogen source is chlorine (Cl), it can be included in the composition for the first to third light-emitting layers as a complex salt with the metal contained in the metal complex.

[0035] [Electron transport layer] The electron transport layer 24ET Ｒ ・24ET Ｇ ・24ET Ｂ is a layer that transports electrons from the cathode 25 side toward the light-emitting layer 24EM Ｒ ・24EM Ｇ ・24EM Ｂ Further, the electron transport layer 24ET Ｒ ・24ET Ｇ ・24ET Ｂ can also be a layer that blocks the holes transported from the anode 22 side so that the cathode 25 side does not transport them.

[0036] The electron transport layer 24ET Ｒ ・We24ET Ｇ ・24ET Ｂ ＢThe electron-transporting material (functional layer material) included is not particularly limited as long as it is an electron-transporting material that can stabilize the transport of electrons to the light-emitting layer, and includes metal oxides containing at least one metal selected from zinc, magnesium, aluminum, and titanium, and said metal oxide may be nanoparticles. More specifically, examples of metal oxide nanoparticles include ZnO, ZnS, ZrO, MgZnO, AlZnO, TiO ２ Examples include nanoparticles such as GaNO.

[0037] Electron transport layer 24ET Ｒ ・24ET Ｇ ・24ET Ｂ Of these, at least the electron transport layer 24ET Ｒ Furthermore, the first element is often added, and the electron transport layer 24ET Ｇ It is more preferable that a second element is added, and furthermore, the electron transport layer 24ET Ｂ A third element may be added to it. The first to third elements are at least one element selected from Group 16 and Group 17. Here, the element is the light-emitting layer 24EM Ｒ ・24EM Ｇ ・24EM Ｂ The same elements as those contained in the composition for the light-emitting layer used to form the light-emitting layer may be included. As described later, the light-emitting layer 24EM Ｒ ・24EM Ｇ ・24EM Ｂ From electron transport layer 24ET Ｒ ・24ET Ｇ ・24ET Ｂ , luminescent layer 24EM Ｒ ・24EM Ｇ ・24EM Ｂ The elements contained in it are moving by seeping out. This causes the light-emitting layer 24EM to move. Ｒ and electron transport layer 24ET Ｒ The two contain the same elements, and the light-emitting layer 24EM Ｇ and electron transport layer 24ET Ｇ The two contain the same elements, and the light-emitting layer 24EM Ｂ and electron transport layer 24ET Ｂ They contain the same element.

[0038] Electron transport layer 24ET Ｒ ・24ET Ｇ ・24ET Ｂ The concentration of the added elements has a concentration gradient in the thickness direction of the electron transport layer, and this concentration gradient is such that the concentration increases as you approach the interface between the light-emitting layer and the functional layer. Electron transport layer 24ET Ｒ ・24ET Ｇ ・24ET Ｂ This is the light-emitting layer 24EM Ｒ ・24EM Ｇ ・24EM Ｂ Due to the leaching of elements, a concentration gradient of elements may be created, with the concentration increasing as one approaches the interface between the light-emitting layer and the electron transport layer. Furthermore, the light-emitting layer 24EM Ｒ ・24EM Ｇ ・24EM Ｂ In each of these, the electron transport layer 24ET Ｒ ・24ET Ｇ ・24ET Ｂ A concentration gradient of the element is formed due to the movement of the element. As a result, the light-emitting layer 24EM Ｒ and electron transport layer 24ET Ｒ The difference in energy levels between LUMO and the luminescent layer 24EM Ｇ and electron transport layer 24ET Ｇ The difference in energy levels between LUMO and the luminescent layer 24EM Ｂ and electron transport layer 24ET Ｂ The difference in LUMO energy levels between each light-emitting layer and the electron transport layer, such as the difference in LUMO energy levels between the two layers, is small, and more preferably, is adjusted to be 0.2 eV or less in absolute value. This makes it possible to reduce the difference in characteristics when a predetermined voltage is applied to each of the light-emitting elements 5R, 5G, and 5B, and to facilitate the control of the current drive of the display device. Here, the difference in LUMO energy levels between the light-emitting layer and the electron transport layer can be expressed as the LUMO depth of the light-emitting layer relative to the electron transport layer. Furthermore, as will be described later, the light-emitting layer 24EM Ｒ ・24EM Ｇ ・24EM Ｂ By applying a reverse bias voltage to the electron transport layer 24ET Ｒ・24ET Ｇ ・24ET Ｂ The elements may be induced by electrophoresis.

[0039] Figure 4 shows an example of the LUMO energy levels in each layer of the functional layers 24R, 24G, and 24B of the light-emitting elements 5R, 5G, and 5B of the display device 1 according to one embodiment. The composition of each layer in the functional layers 24R, 24G, and 24B shown in Figure 4 is as shown in Table 1 below. The material of the hole transport layer 24HT common to the functional layers 24R, 24G, and 24B has a LUMO energy level of -2.4 eV and is composed of TFB, poly-TPD, or PVK.

[0040]

[0041] The electron transport layer 24ET shown in Figure 4 Ｒ ・24ET Ｇ ・24ET Ｂ The energy levels of the LUMO in each of these are determined by the elemental concentration gradient, in the electron transport layer 24ET Ｒ ・24ET Ｇ ・24ET Ｂ It is sloped internally. Note that in Figure 4, the electron transport layer 24ET Ｒ ・24ET Ｇ ・24ET Ｂ This conceptual diagram illustrates how the concentration gradient of elements in the electron transport layer creates an energy level gradient in the LUMO.

[0042] Furthermore, as illustrated in Figure 4, the light-emitting layer 24EM in the functional layer 24B Ｂ , and electron transport layer 24ET ＢThe elements may not include sulfur derived from a sulfide semiconductor matrix, nor Group 16 and Group 17 elements, such as halogens. In one embodiment, a display device can be configured by adding Group 16 and Group 17 elements to the functional layers other than the functional layer with the largest difference in LUMO energy levels between the luminescent layer and the electron transport layer, based on a plurality of luminescent layers emitting light of different wavelengths. However, this is not limited to the functional layers 24R, 24G, and 24B, where Group 16 and Group 17 elements are added to each electron transport layer, and the LUMO energy levels of each electron transport layer are adjusted.

[0043] As shown in Figure 4, electron transport layer 24ET Ｒ , and electron transport layer 24ET Ｇ Each of these is the electron transport layer 24ET, which is the first functional layer. Ｒ The second functional layer is the electron transport layer 24ET. Ｇ The LUMO energy levels are adjusted to be deeper than the above. Figure 4 shows the electron transport layer 24ET. Ｒ The electron transport layer 24ET Ｇ The energy level gradient of LUMO illustrates that the concentrations of Group 16 and Group 17 elements are higher than those of Group 16.

[0044] Alternatively, in one embodiment, the electron transport layer 24ET provided by the first functional layer Ｒ The first element contained in is electron transport layer 24ET Ｇ It is preferable that the ionization energy is greater than that of the second element contained in the first functional layer, electron transport layer 24ET Ｒ The second functional layer is the electron transport layer 24ET. Ｇ The LUMO energy levels may be adjusted to be deeper than the specified level. Electron transport layer 24ET Ｒ The ionization energy of the first element contained in and the electron transport layer 24ET Ｇ By selecting the ionization energy of the second element contained in, the electron transport layer 24ET Ｒ and electron transport layer 24ET Ｇ electron transport layer 24ET ＢThe difference in LUMO energy levels between each electron transport layer, including the electron transport layer 24ET, and each light-emitting layer may be adjusted to be small. Ｒ The ionization energy of the first element contained in and the electron transport layer 24ET Ｇ The ionization energy of the second element contained in and the electron transport layer 24ET Ｂ The ionization energy of the third element may be selected to adjust the difference in LUMO energy levels between each electron transport layer and each light-emitting layer to be small. For example, the electron transport layer 24ET of the third functional layer Ｂ If it contains a third element, the ionization energy of the third element is the electron transport layer 24ET Ｇ It is preferable that the ionization energy of the first element is lower than that of the second element contained in the first element. Furthermore, instead of adjusting the ionization energy by selecting the first, second, and third elements, the difference in LUMO energy levels between each electron transport layer and each light-emitting layer may be reduced by adjusting the concentrations of the first, second, and third elements. In this case, for example, the concentration of the second element is adjusted to be lower than that of the first element, and the concentration of the third element is adjusted to be lower than that of the second element. Alternatively, the first, second, and third elements may be selected, and the differences in LUMO energy levels between each electron transport layer and each light-emitting layer may be reduced by adjusting the concentrations of the first, second, and third elements. Here, the ionization energy is the energy difference (absolute value) between the vacuum level and the top of the valence band. For example, for the elements of Group 17, it is chlorine (1251.2 kJ / mol (13.0 eV)), bromine (1139.9 kJ / mol (11.8 eV)), iodine (1008.4 kJ / mol (10.5 eV)), and fluorine (1681.0 kJ / mol (17.4 eV)).

[0045] (Substrate, etc.) As shown in Figure 2, the substrate 12 may be a resin substrate made of a resin material such as polyimide, or it may be a glass substrate. In this embodiment, since the display device 1 is a flexible display device, the case in which a resin substrate made of a resin material such as polyimide is used as the substrate 12 will be described as an example, but it is not limited to this. When the display device 1 is a non-flexible display device, a glass substrate can be used as the substrate 12.

[0046] The barrier layer 3 is a layer that prevents foreign substances such as water and oxygen from entering the transistor TR, light-emitting element 5R, light-emitting element 5G, and light-emitting element 5B. For example, it can be composed of a silicon oxide film, a silicon nitride film, or a silicon oxynitride film, or a laminate of these, formed by the CVD method.

[0047] The transistor TR portion of the thin-film transistor layer 4, which includes the transistor TR, comprises a semiconductor film SEM and doped semiconductor films SEM' and SEM'', an inorganic insulating film 16, a gate electrode G, an inorganic insulating film 18, an inorganic insulating film 20, a source electrode S and a drain electrode D, and a planarization film 21. The portion of the thin-film transistor layer 4, which includes the transistor TR, other than the transistor TR portion, comprises the inorganic insulating film 16, the inorganic insulating film 18, the inorganic insulating film 20, and the planarization film 21.

[0048] The semiconductor film SEM, SEM', and SEM'' may be composed of, for example, low-temperature polysilicon (LTPS) or oxide semiconductors (for example, In-Ga-Zn-O semiconductors). In this embodiment, the case in which the transistor TR has a top-gate structure is described as an example, but it is not limited to this, and the transistor TR may have a bottom-gate structure.

[0049] The gate electrode G, source electrode S, and drain electrode D can be made of a single-layer or multilayer film of a metal containing, for example, at least one of aluminum, tungsten, molybdenum, tantalum, chromium, titanium, or copper.

[0050] The inorganic insulating film 16, inorganic insulating film 18, and inorganic insulating film 20 can be composed of, for example, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a laminate of these, formed by the CVD method.

[0051] The planarization film 21 can be made of, for example, a coatable organic material such as polyimide or acrylic.

[0052] The insulating bank 23 covering the edges of the anode 22 of each of the light-emitting elements 5R, 5G, and 5B can be formed, for example, by coating an organic material such as polyimide or acrylic and then patterning it using photolithography. In one embodiment, the case in which the bank 23 is provided is described as an example, but the bank 23 may not be provided.

[0053] The sealing layer 6 is a light-transmitting film and can be composed of, for example, an inorganic sealing film 26 covering the cathode 25, an organic film 27 above the inorganic sealing film 26, and an inorganic sealing film 28 above the organic film 27. The sealing layer 6 prevents foreign substances such as water and oxygen from penetrating the light-emitting elements 5R, 5G, and 5B.

[0054] The inorganic encapsulation film 26 and the inorganic encapsulation film 28 are each inorganic films, and can be composed of, for example, silicon oxide films, silicon nitride films, or silicon oxynitride films formed by the CVD method, or laminated films thereof. The organic film 27 is a translucent organic film with a planarization effect, and can be composed of, for example, a coatable organic material such as acrylic. The organic film 27 may be formed by, for example, the inkjet method. In this embodiment, the case in which the encapsulation layer 6 is formed by two inorganic films and one organic film provided between two inorganic films has been described as an example, but the stacking order of the two inorganic films and one organic film is not limited to this. Furthermore, the encapsulation layer 6 may be composed of inorganic films only, or of organic films only, or of one inorganic film and two organic films, or of two or more inorganic films and two or more organic films.

[0055] The functional film 39 is, for example, a film having at least one of the following functions: optical compensation function, touch sensor function, and protective function.

[0056] <Modification> In the above, the electron transport layer 24ET is the first functional layer. Ｒ The second functional layer is the electron transport layer 24ET. Ｇ While a display device has been described that includes a light-emitting element tuned to have deeper LUMO energy levels than described above, this disclosure is not limited to the above embodiments.

[0057] For example, in one modified display device, the first light-emitting layer and the first functional layer, which is a hole transport layer, in contact with the first light-emitting layer, each contain an element from either Group 16 or Group 17, and the second light-emitting layer and the second functional layer, which is a hole transport layer, in contact with the second light-emitting layer, each contain an element from either Group 16 or Group 17, thereby adjusting so that the difference in HOMO energy levels between the first light-emitting layer and the first functional layer, which is a hole transport layer, and the difference in HOMO energy levels between the second light-emitting layer and the second functional layer, which is a hole transport layer, are substantially equal.

[0058] <Method of Manufacturing a Display Device (First Embodiment)> The method of manufacturing the display device 1 will be explained using Figures 5 and 6. Figure 5 is a diagram illustrating the outline of the process up to the step of forming the light-emitting layer, which is included in the method of manufacturing the display device 1 according to one embodiment. Figure 6 shows the light-emitting layer 24EM included in the method of manufacturing the display device 1 according to one embodiment. Ｒ ・24EM Ｇ By moving elements from the electron transport layer 24ET Ｒ ・24ET Ｇ This diagram outlines the process up to the formation stage.

[0059] As shown in the upper and middle sections of Figure 5, the manufacturing method of the display device 1 involves coating a first light-emitting layer composition containing a first light-emitting layer material onto a thin-film transistor layer (substrate) 4, thereby creating the light-emitting layer 24EM Ｇ The process involves forming the second light-emitting layer and, as shown in the lower part of Figure 5, coating the second light-emitting layer composition containing the second light-emitting layer material to form the second light-emitting layer 24EM ＲThe process includes the step of forming the first and second light-emitting layers 24EM, as shown in the upper and middle sections of Figure 6. Ｒ ・24EM Ｇ The electron transport layer 24ET is a functional layer that comes into contact with the electron transport layer. Ｒ ・24ET Ｇ The process includes the step of forming the first and second light-emitting layers 24EM as shown in the lower part of Figure 6, and after the step of forming the cathode 25, the first and second light-emitting layers 24EM Ｒ ・24EM Ｇ The elements contained in are moved, and the first light-emitting layer 24EM Ｒ The electron transport layer 24ET is a functional layer containing elements. Ｒ And, the electron transport layer 24ET, which is a second functional layer containing the elements contained in the second light-emitting layer. Ｇ It forms.

[0060] As shown in the upper part of Figure 5, in the manufacturing method of the display device 1, it is preferable to form a hole transport layer 24HT on the anode 22 and the bank 23 surrounding the anode 22.

[0061] Light-emitting layer 24EM Ｒ A first light-emitting layer composition used in the process of forming the first light-emitting layer, and the light-emitting layer 24EM Ｇ The first and second light-emitting layer compositions used in the process of forming the first and second light-emitting layer compositions each contain quantum dots that emit light of predetermined wavelengths, but different from each other. Each of the first and second light-emitting layer compositions has either a Group 16 or Group 17 element added to it, and these elements are derived from an organic ligand or a halogen ion. Here, the Group 16 element is preferably sulfur (S), which may be sulfur derived from the ligand of the metal complex described above. The Group 17 element is a halogen derived from a halogen source, and is more preferably chlorine (Cl). For convenience, the organic ligands, halogen ions, metal complexes, and halogen sources that may be included in the light-emitting layer compositions may be referred to as element sources in this specification.

[0062] The amount of elemental source added to each light-emitting layer composition should be adjusted according to the LUMO energy level of each light-emitting layer and the LUMO energy level of the electron transport layer to be in contact with the light-emitting layer. More specifically, first, measure the LUMO energy level of each light-emitting layer before element addition and the LUMO energy level of the electron transport layer before element addition, and determine the amount of elemental source to add from the difference in LUMO energy levels in each light-emitting layer. Next, design the difference in LUMO energy levels in each light-emitting layer and the ionization energy of the element to be added, and adjust the amount of element to be added to the light-emitting layer. It is advisable to adjust the amount of elemental source to seep into the electron transport layer from the amount of elemental source added to each light-emitting layer. For example, if the element is fluorine, the change in the LUMO energy level due to the movement of fluorine to the light-emitting layer may be about 0.5 to 1.5 eV; if the element is chlorine, the change in the LUMO energy level due to the movement of chlorine to the light-emitting layer may be about 0.1 to 1.0 eV; if the element is bromine, the change in the LUMO energy level due to the movement of bromine to the light-emitting layer may be about 0.1 to 0.7 eV; and if the element is iodine, the change in the LUMO energy level due to the movement of iodine to the light-emitting layer may be about 0.01 to 0.5 eV. Considering the element and the change in the LUMO energy level, in order to deepen the LUMO energy level of the electron transport layer by about -0.1 eV, for example, if the element source is chloride ions, the concentration of chloride ions contained in the light-emitting layer composition should be adjusted so that the concentration is about 1.0 to 10.0 mol%. Furthermore, for example, the amount of elements such as organic ligands, metal complexes, and halogen sources contained in each light-emitting layer composition is adjusted according to the difference in the LUMO energy levels of each light-emitting layer, and light-emitting layer 24EM Ｒ ・24EM Ｇ A composition containing the same electron-transporting material may be used as the composition for forming the electron transport layer on top of it (composition for the electron transport layer).

[0063] The LUMO levels of each light-emitting layer may be measured and calculated by the following methods: (1) Measure the HOMO of each light-emitting layer by PYS isophotoelectron spectroscopy and calculate the LUMO by adding the band gap to the absorption of these layers. (2) Measure the LUMO of each light-emitting layer directly by inverse photoelectron spectroscopy.

[0064] The luminescent layer composition contains quantum dots (QDs), the above-mentioned organic ligands and / or halogen ions as elemental sources, and may also contain metal complexes and halogen sources as matrix precursors. The organic ligands, including the above-mentioned octanthiol, contained in the quantum dots (QDs) in each luminescent layer composition exhibit surface activity and are therefore soluble in both polar and low-polarity solvents. Furthermore, when octanthiol is used as the organic ligand, the thiol group of octanthiol can be efficiently coordinated to the shell of the quantum dot (QD) (e.g., zinc sulfide (ZnS)).

[0065] Furthermore, because the emissive layer composition contains a metal complex and a halogen source, exchange may occur between the organic ligand of the quantum dot (QD) and the ligand of the metal complex, and further, exchange may occur between the organic ligand of the quantum dot (QD) and the ligand of the metal complex and the halogen. By preparing the emissive layer composition so as to dissolve an excess amount of halogen ions relative to the quantum dot (QD), an emissive layer 24EM can be formed in which halogen ligands are coordinated to defects on the surface of the quantum dot (QD). Ｒ EM Ｇ This can be formed. In this case, the average concentration of halogen atoms within 1 nm from the outermost surface of each quantum dot (QD) may be 10%, 50%, or 100% higher than the average concentration of halogen atoms at other locations. The halogen ions contained in the light-emitting layer composition may be halogen sources, and more specifically, chloride ions derived from hydrochloric acid.

[0066] The light-emitting layer composition may contain a low-polarity solvent (also called a quantum dot dispersion medium) such as n-hexane, n-octane, n-decane, toluene, or phenylcyclohexane, and may also contain a dispersion material. Furthermore, the light-emitting layer composition may contain a solvent such as dimethylformamide (DMF) or dimethyl sulfoxide (DMSO).

[0067] The composition for the light-emitting layer is coated, for example, by a spin coating method or an inkjet method, to form the light-emitting layer 24EM Ｒ EM Ｇ This can be achieved by forming the following. As shown in the middle and lower sections of Figure 5, for example, the sub-pixels can be colored separately by resist patterning using a resist layer 60 and a resist layer 61.

[0068] The light-emitting layer 24EM is formed by coating the light-emitting layer composition shown in the upper part of Figure 6. Ｒ EM Ｇ For example, a matrix of sulfide semiconductors derived from metal complexes may be formed by heating or ultraviolet exposure. (Emitting layer 24EM) Ｒ EM Ｇ When forming a sulfide semiconductor matrix by heating, for example, heating at a temperature of 200°C or lower is sufficient. Furthermore, this allows the light-emitting layer 24EM to be formed. Ｒ EM Ｇ A matrix of sulfide semiconductors derived from metal complexes can be formed. Furthermore, when forming the sulfide semiconductor matrix by ultraviolet exposure, the light-emitting layer 24EM Ｒ EM Ｇ Conditions for exposure include, for example, ultraviolet light with a wavelength of about 150 to 450 nm and electron beams, and it is preferable to irradiate with ultraviolet light with a wavelength of 150 to 330 nm. This ultraviolet light may be g-line (wavelength 436 nm), h-line (wavelength 405 nm), or i-line (wavelength 365 nm) from a high-pressure mercury lamp, but it is preferable to use an excimer laser (wavelength 150 to 248 nm).

[0069] Next, as shown in the middle section of Figure 6, the light-emitting layer 24EM Ｒ EM ＧAn electron transport layer 24ET can be formed by coating a substrate on which an electron transport material has been formed with an electron transport layer 24ET. The composition used to form the electron transport layer comprises an electron transport material and a solvent, and the electron transport material is the above-mentioned ZnO, ZnS, ZrO, MgZnO, AlZnO, TiO ２ The electron transport layer composition containing the electron transport material may be applied collectively to the subpixels of multiple light-emitting elements by an inkjet method, spin coating method, dip coating method, etc., or it may be applied separately to form a pattern by ejecting droplets of the composition into the inside of the bank 23 for each subpixel by an inkjet method, etc.

[0070] The thin-film transistor layer 4 coated with the electron transport layer composition is then heated to remove the solvent contained in the electron transport layer composition, thereby forming the electron transport layer 24ET. At this time, the light-emitting layer 24EM Ｒ EM Ｇ From there, it seeps out toward the electron transport layer 24ET, into the light-emitting layer 24EM Ｒ EM Ｇ The elements of Group 16 and Group 17 contained in are moved. At this time, heating at a temperature of 150°C or less, preferably 100°C or less, for 5 hours or less, preferably 3 hours or less, is sufficient to move the elements of Group 16 and Group 17 toward the electron transport layer 24ET by causing them to seep out. As a result, the electron transport layer 24ET and the light-emitting layer 24EM Ｒ EM Ｇ It is preferable to move the elements of Group 16 and Group 17 into the electron transport layer 24ET in such a way that the concentration gradient increases as it approaches the interface, and then remove the solvent.

[0071] After forming the electron transport layer 24ET and before forming the cathode 25, a process damage protection layer (not shown) may be formed to temporarily protect the electron transport layer 24ET. The process damage protection layer is a layer that protects the electron transport layer 24ET, and when forming the cathode 25, it protects the electron transport layer 24ET and the light-emitting layer EM provided in the light-emitting region HR. Ｒ EM ＧThis reduces damage to the hole transport layer 24HT. The process damage protection layer may be formed, for example, by a resist composition for forming a resist layer.

[0072] Also, as shown in the lower part of Figure 6, the light-emitting layer 24EM Ｒ EM Ｇ In the transfer of elements from to the electron transport layer 24ET, after forming a cathode 25 on the electron transport layer 24ET, a reverse bias voltage is applied between the anode 22 and the cathode 25, thereby creating the first light-emitting layer 24EM Ｒ The elements contained in are moved to the electron transport layer 24ET, and the second light-emitting layer 24EM Ｇ The elements contained in the second light-emitting layer 24EM Ｇ It may be moved from there into the electron transport layer 24ET. This will move the light-emitting layer 24EM into the electron transport layer 24ET. Ｒ electron transport layer 24ET containing the same elements Ｒ A light-emitting layer 24EM is formed within the electron transport layer 24ET. Ｇ electron transport layer 24ET containing the same elements Ｇ It is possible to form this.

[0073] For example, the reverse bias voltage applied between the anode and cathode should be designed appropriately according to the type of light-emitting element and should not be limited, but it should be applied to the light-emitting element in a way that does not damage it.

[0074] <Method for Manufacturing a Display Device (Second Embodiment)> The method for manufacturing a display device according to this disclosure is not limited to the manufacturing method (first embodiment) described above. As shown in Figure 7, for example, the method for manufacturing a display device according to one embodiment (second embodiment) first uses first and second light-emitting layer compositions which contain quantum dots (QD) but do not contain element sources such as organic ligands to light-emitting layer 24EM Ｒ , and the light-emitting layer 24EM Ｇ It would be good to form this.

[0075] Next, the light-emitting layer 24EM Ｒ A first composition containing an element source from either Group 16 or Group 17 is coated on top, and an emissive layer 24EM is formed. ＧA second composition containing an element source from either Group 16 or Group 17 may be applied on top. This then creates the luminescent layer 24EM Ｒ and electron transport layer ET Ｒ Between and the light-emitting layer 24EM Ｇ and electron transport layer ET Ｇ The concentrations of Group 16 and Group 17 elements between these two points can be more effectively adjusted.

[0076] <Method for Manufacturing a Display Device (Third Embodiment)> The method for manufacturing a display device according to this disclosure is not limited to the manufacturing methods (first and second embodiments) described above. As shown in Figure 8, for example, the method for manufacturing a display device according to one embodiment (third embodiment) is a first composition L １ and the second composition L ２ In the coating process, the first and second compositions may be applied separately by a vapor deposition method using a mask, a mist method, or a spray method.

[0077] <Method for Manufacturing a Display Device (Fourth Embodiment)> The method for manufacturing a display device according to this disclosure is not limited to the manufacturing methods described above (first to third embodiments). As shown in Figure 9, for example, the method for manufacturing a display device according to one embodiment (fourth embodiment) is a first light-emitting layer EM Ｒ By coating the first electron transport layer composition (first functional layer composition) on top, the electron transport layer ET Ｒ Forms a second light-emitting layer EM Ｇ By applying a second electron transport layer composition (second functional layer composition) on top, the second electron transport layer ET Ｇ A first electron transport layer composition may be formed. Here, the first electron transport layer composition comprises an electron transport material and an element source, and the first light-emitting layer EM Ｒ The concentration of the element source should be adjusted according to the energy level of the LUMO, and the composition for the second electron transport layer includes an electron transport material and an element source, and the second light-emitting layer EM Ｇ The concentration of the elemental source should be adjusted according to the energy levels of the LUMO.

[0078] <Method for Manufacturing a Display Device (Fifth Embodiment)> The method for manufacturing a display device according to this disclosure is not limited to the manufacturing methods (first to fourth embodiments) described above. As shown in Figure 10, for example, in the method for manufacturing a display device according to one embodiment (fifth embodiment), in the step of coating the first electron transport layer composition (functional layer composition), a plurality of first electron transport layer compositions are coated, and in the step of coating the second electron transport layer composition, a plurality of second functional layer compositions are coated, and each of the plurality of first functional layer compositions may have a different concentration of element source, and each of the plurality of second functional layer compositions may have a different concentration of element source.

[0079] As a result, the light-emitting layer 24EM Ｒ Above is the electron transport layer ET from the first electron transport layer composition. Ｒ Only is formed, and the light-emitting layer 24EM Ｒ Above is the electron transport layer ET from the first electron transport layer composition. Ｇ－１ The electron transport layer ET is formed by a second electron transport layer composition having a different elemental concentration from the first electron transport layer composition. Ｇ－１ Above is the electron transport layer ET Ｇ－２ This will form the light-emitting layer 24EM. Ｒ and electron transport layer ET Ｒ Between and the light-emitting layer 24EM Ｇ and electron transport layer ET Ｇ－１ and ET Ｇ－２ The concentrations of Group 16 and Group 17 elements between them can be suitably adjusted, and the light-emitting layer 24EM Ｒ and electron transport layer ET Ｒ The difference in LUMO between the two, and the light-emitting layer 24EM Ｇ and electron transport layer ET Ｇ The difference in LUMO between and can be suitably adjusted.

[0080] <Display device according to a second modified example> The display device according to the present disclosure is not limited to the above-described embodiment and modified example. The display device according to one modified example (second modified example) comprises a display area DA having a light-emitting area where the light-emitting element emits light and a non-light-emitting area surrounding the light-emitting area, and a light-emitting layer 24EM Ｒ ・24EM Ｇ ・24EM ＢHowever, it is preferable that the configuration overlaps in the non-luminescent region NHR.

[0081] This effectively reduces the occurrence of leakage current caused by the drive voltage in the non-luminescent region (NHR).

[0082] The above describes an example of a quantum dot light-emitting diode (QLED) in which the light-emitting layer contains quantum dots as the light-emitting material. However, the invention is not limited to this, and the light-emitting layer may also contain an organic light-emitting layer material instead of quantum dots (QD) as the light-emitting material, such as an OLED (organic light-emitting diode). When the light-emitting layer is an OLED containing an organic light-emitting layer material, the LUMO level of the organic light-emitting layer material can be determined by cyclic voltammetry.

[0083] This disclosure is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of this disclosure. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

[0084] 1 Display device 4 Thin-film transistor layer (substrate) 5R Light-emitting element (red light-emitting element) 5G Light-emitting element (green light-emitting element) 5B Light-emitting element (blue light-emitting element) 22 Anode 23 Bank 24R Functional layer 24G Functional layer 24B Functional layer 24EM Ｒ Light-emitting layer (first light-emitting layer) 24EM Ｇ Light-emitting layer (second light-emitting layer) 24EM Ｂ Light-emitting layer (third light-emitting layer): 24HT Hole transport layer (another functional layer): 24ET Electron transport layer: 24ET Ｒ Electron transport layer (first functional layer) 24ET Ｇ Electron transport layer (second functional layer) 24ET ＢElectron transport layer (third functional layer) 25 Cathode 26, 28 Inorganic encapsulation film 27 Organic film 39 Functional film 60, 61 Resist layer PIX Pixel RSP Red subpixel GSP Green subpixel BSP Blue subpixel DA Display area NDA Frame area HR Emitting area NHR Non-emitting area

Claims

1. A display device comprising a plurality of light-emitting elements in a display area provided on a substrate, the first light-emitting element comprising a first light-emitting layer and a first functional layer in contact with the first light-emitting layer between a first anode and a first cathode, and a second light-emitting element comprising a second light-emitting layer and a second functional layer in contact with the second light-emitting layer between a second anode and a second cathode, wherein the first and second light-emitting layers emit light in different colors from each other, and a first element consisting of either Group 16 or Group 17 is added to the first functional layer.

2. The display device according to claim 1, wherein the concentration of the element has a concentration gradient in the thickness direction of the first functional layer.

3. The display device according to claim 2, wherein the concentration gradient is a concentration gradient in which the concentration increases as it approaches the interface between the first light-emitting layer and the first functional layer.

4. The display device according to any one of claims 1 to 3, wherein the first and second functional layers are electron transport layers laminated between the first or second cathode and the first or second light-emitting layer.

5. The display device according to claim 4, wherein the electron transport layer comprises a metal oxide, and the metal oxide comprises at least one metal selected from zinc, magnesium, aluminum, and titanium.

6. The display device according to claim 5, wherein the metal oxide is a nanoparticle.

7. The display device according to any one of claims 1 to 6, wherein the first element is sulfur.

8. The display device according to any one of claims 1 to 7, wherein the first and second light-emitting layers include quantum dots.

9. The display device according to any one of claims 1 to 8, wherein a second element consisting of either group 16 or group 17 is added to the second functional layer, and the concentration of the first element added to the first functional layer is greater than the concentration of the second element added to the second functional layer.

10. The display device according to claim 9, wherein the wavelength of light emitted by the first light-emitting layer is longer than the wavelength of light emitted by the second light-emitting layer.

11. The display device according to claim 9 or 10, wherein the display area comprises a third light-emitting layer, the third light-emitting layer comprising a third light-emitting layer and a third functional layer in contact with the third light-emitting layer between a third anode and a third cathode, and a third element consisting of either group 16 or group 17 is added to the third functional layer.

12. The display device according to claim 11, wherein the wavelength of light emitted by the third light-emitting layer is shorter than the wavelength of light emitted by the first and second light-emitting layers.

13. The display device according to claim 12, wherein the concentration of the third element added to the third functional layer is smaller than the concentration of the first element added to the first functional layer and the concentration of the second element added to the second functional layer.

14. The display device according to any one of claims 9 to 13, wherein the ionization energy of the first element is greater than the ionization energy of the second element.

15. The display device according to any one of claims 11 to 13, wherein the ionization energy of the third element is less than the ionization energy of the first element and the ionization energy of the second element.

16. The display device according to any one of claims 1 to 15, wherein the difference between the depth of the LUMO of the first functional layer relative to the first light-emitting layer and the difference between the depth of the LUMO of the second functional layer relative to the second light-emitting layer is 0.2 eV or less.

17. The display device according to any one of claims 1 to 16, wherein each of the plurality of light-emitting elements further comprises another functional layer between the first cathode and the first light-emitting layer and between the second cathode and the second light-emitting layer, the other functional layer being a hole transport layer.

18. The display device according to any one of claims 1 to 17, wherein the display area comprises a light-emitting region where the light-emitting element emits light and a non-light-emitting region surrounding the light-emitting region, and the first and second light-emitting layers overlap on the non-light-emitting region.

19. The display device according to claim 18, wherein the display area includes a light-emitting element having a third light-emitting layer, and the first, second, and third light-emitting layers overlap on the non-light-emitting area.

20. A method for manufacturing a display device having a plurality of light-emitting elements that emit light in two or more colors in a display area provided on a substrate, comprising: a step of forming a first light-emitting layer by coating a first light-emitting layer composition containing a first light-emitting layer material onto a first anode; a step of forming a second light-emitting layer by coating a second light-emitting layer composition containing a second light-emitting layer material onto a second anode; a step of coating a first composition containing a first element from either Group 16 or Group 17 onto the first light-emitting layer, and a step of coating a second composition containing a second element from either Group 16 or Group 17 onto the second light-emitting layer; a step of forming a functional layer that contacts the first and second light-emitting layers by coating a functional layer composition containing a functional layer material onto the first and second light-emitting layers; and a step of forming first and second cathodes on the functional layer. A method for manufacturing a display device, comprising transferring elements contained in the first and second light-emitting layers to the functional layers to form a first functional layer containing the first element and a second functional layer containing the second element.

21. A method for manufacturing a display device having a plurality of light-emitting elements that emit light in two or more colors in a display area provided on a substrate, comprising: forming a first light-emitting layer by coating a first light-emitting layer composition comprising a first light-emitting layer material and a first element selected from either Group 16 or Group 17 onto a first anode; forming a second light-emitting layer by coating a second light-emitting layer composition comprising a second light-emitting layer material and a second element selected from either Group 16 or Group 17 onto a second anode; forming a functional layer that contacts the first and second light-emitting layers by coating a functional layer composition comprising a functional layer material onto the first and second light-emitting layers; and forming first and second cathodes on the functional layer. A method for manufacturing a display device, comprising transferring the first and second elements contained in the first and second light-emitting layers to the functional layer to form a first functional layer containing the first element and a second functional layer containing the second element.

22. The method for manufacturing a display device according to claim 20 or 21, wherein in the step of forming the first and second light-emitting layers, the first and second light-emitting layers are formed by resist patterning.

23. The method for manufacturing a display device according to claim 20, wherein in the step of coating the first and second compositions, the first and second compositions are coated separately by a vapor deposition method using a mask, a mist method, or a spray method.

24. A method for manufacturing a display device according to any one of claims 20 to 23, wherein the step of forming the functional layer includes the steps of coating the first light-emitting layer with a first functional layer composition comprising a first element from either Group 16 or Group 17, and coating the second light-emitting layer with a second functional layer composition comprising a second element from either Group 16 or Group 17.

25. The method for manufacturing a display device according to claim 24, wherein in the step of coating the first functional layer composition, a plurality of first functional layer compositions are coated, and in the step of coating the second functional layer composition, a plurality of second functional layer compositions are coated, each of the plurality of first functional layer compositions has a different concentration of the first element, and each of the plurality of second functional layer compositions has a different concentration of the second element.

26. A method for manufacturing a display device according to any one of claims 20 to 25, wherein the elements contained in the first and second light-emitting layers are moved by applying a reverse bias voltage to the anode and cathode.

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