Light-emitting element, display device, dispersion liquid of metal oxide nanoparticles, and method for manufacturing metal oxide layer

Abstract

A red light-emitting element (5R), which is a light-emitting element, includes: an anode that is a lower electrode (22); a cathode that is an upper electrode (25); a red light-emitting layer (24 REM) that is provided between the anode that is the lower electrode (22) and the cathode that is the upper electrode (25); and a first charge transport layer (24ET) that is a functional layer provided between the red light-emitting layer (24 REM) and the cathode that is the upper electrode (25). The first charge transport layer (24ET) that is the functional layer includes electron-transporting metal oxide nanoparticles (ETNP) and alcohol protection groups (APG).

Description

Light-emitting element, display device, dispersion of metal oxide nanoparticles, and method for manufacturing a metal oxide layer

[0001] This disclosure relates to a light-emitting element, a display device, a dispersion of metal oxide nanoparticles, and a method for producing a metal oxide layer.

[0002] In recent years, various display devices equipped with light-emitting elements have been developed, and in particular, display devices equipped with OLEDs (Organic Light Emitting Diodes) or QLEDs (Quantum Dot Light Emitting Diodes) have attracted considerable attention due to their ability to achieve low power consumption, thin design, and high image quality.

[0003] Patent Document 1 describes a light-emitting device comprising a charge transport layer containing a metal oxide between one of the anode and cathode and the light-emitting layer.

[0004] Japanese Patent Publication No. 2012-23388

[0005] In the metal oxide contained in the charge transport layer of the light-emitting device described in Patent Document 1, a large number of hydroxyl groups (alcohol groups) remain, which can negatively affect the light-emitting layer or cause defect emission in the charge transport layer containing the metal oxide.

[0006] One aspect of this disclosure aims to provide a dispersion of metal oxide nanoparticles used to form a layer containing a metal oxide that can suppress adverse effects on the light-emitting layer and the occurrence of defect emission in the layer containing the metal oxide, a method for manufacturing a metal oxide layer, and a light-emitting device and a display device equipped with such a functional layer containing a metal oxide.

[0007] To solve the above problems, the light-emitting element of the present disclosure includes an anode, a cathode, a light-emitting layer provided between the anode and the cathode, and a functional layer provided between one of the anode and the cathode and the light-emitting layer, wherein the functional layer includes a metal oxide and an alcohol protecting group.

[0008] To solve the above problems, the light-emitting element of the present disclosure includes an anode, a cathode, a light-emitting layer provided between the anode and the cathode, and a functional layer provided between one of the anode and the cathode and the light-emitting layer, wherein the functional layer includes a first alcohol protecting group bonded to a leaving group and a second alcohol protecting group bonded to a metal oxide.

[0009] The display device of this disclosure includes the light-emitting element in order to solve the aforementioned problems.

[0010] The present disclosure provides a method for producing a metal oxide layer, which, in order to solve the above-mentioned problems, includes the steps of: forming a metal oxide layer containing a metal oxide; adding an alcohol protective agent containing an alcohol protecting group to the metal oxide layer; and, after the step of adding the alcohol protective agent, applying energy to the metal oxide layer to react the hydroxyl group contained in the metal oxide with the alcohol protecting group.

[0011] The present disclosure's method for producing a metal oxide layer, in order to solve the aforementioned problems, includes the steps of: preparing a dispersion of metal oxide nanoparticles comprising metal oxide nanoparticles, an alcohol protective agent containing an alcohol protecting group, and a dispersion medium; imparting energy to the dispersion to react the hydroxyl groups contained in the metal oxide nanoparticles with the alcohol protecting group; and forming a metal oxide layer containing an alcohol protecting group using the dispersion after the energy imparting step.

[0012] The present disclosure's method for producing a metal oxide layer includes, in order to solve the above-mentioned problems, the steps of: preparing a dispersion of metal oxide nanoparticles comprising metal oxide nanoparticles, an alcohol protective agent containing an alcohol protecting group, and a dispersion medium; forming a metal oxide layer using the dispersion; and imparting energy to the metal oxide layer to react the hydroxyl groups contained in the metal oxide nanoparticles with the alcohol protecting group.

[0013] The dispersion of metal oxide nanoparticles of this disclosure comprises metal oxide nanoparticles, an alcohol protecting group bonded to the metal oxide nanoparticles, and a dispersion medium in order to solve the above-mentioned problems.

[0014] According to one aspect of this disclosure, a dispersion of metal oxide nanoparticles used to form a layer containing a metal oxide that can suppress adverse effects on the light-emitting layer and the occurrence of defect emission in the layer containing the metal oxide, a method for manufacturing a metal oxide layer, and a light-emitting element and a display device equipped with such a functional layer containing a metal oxide can be provided.

[0015] Figure 3 is a plan view showing the schematic configuration of the display device of Embodiment 1. Figure 4 is a cross-sectional view showing the schematic configuration of the display area of ​​the display device of Embodiment 1. Figure 5 is a cross-sectional view showing the schematic configuration of the red light-emitting element provided in the display device of Embodiment 1. Figure 6 is a diagram showing the schematic configuration of the first charge transport layer provided between the red light-emitting layer and the cathode, which is the upper electrode of the red light-emitting element shown in Figure 3. Figure 7 is a diagram showing an example of an alcohol protective agent containing an alcohol protecting group and a leaving group. Figure 8 is a diagram showing the schematic configuration of another first charge transport layer that can be provided between the red light-emitting layer and the cathode, which is the upper electrode of the red light-emitting element shown in Figure 3. Figure 9 is a diagram showing the schematic configuration of a second charge transport layer provided between the red light-emitting layer and the anode, which is the lower electrode of the red light-emitting element shown in Figure 3. Figure 9 is a diagram showing the process of forming the first charge transport layer shown in Figure 4 using the dispersion of metal oxide nanoparticles to which an alcohol protecting group is bound. This figure shows the process of forming the first charge transport layer shown in Figure 4 using a dispersion of metal oxide nanoparticles that does not contain the alcohol protective agent shown in Figure 9. This figure shows the process of forming the first charge transport layer shown in Figure 6. This figure is intended to explain the difference between the alcohol protective agent shown in Figure 5 and the self-assembled monolayer used to form a self-assembled membrane (SAM).

[0016] The embodiments of this disclosure will be described below with reference to Figures 1 to 13. For the sake of convenience, in the following description, components having the same function as those described in a particular embodiment will be denoted by the same reference numerals, and their descriptions may be omitted.

[0017] [Embodiment 1] Figure 1 is a plan view showing the schematic configuration of the display device 1 of Embodiment 1.

[0018] 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.

[0019] Figure 2 is a cross-sectional view showing a schematic configuration of the display area DA of the display device 1 of Embodiment 1.

[0020] 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, a red light-emitting element 5R, a green light-emitting element 5G, a blue light-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.

[0021] The red subpixel RSP provided in the display area DA of the display device 1 includes a red light-emitting element 5R (light-emitting element), the green subpixel GSP provided in the display area DA of the display device 1 includes a green light-emitting element 5G (light-emitting element), and the blue subpixel BSP provided in the display area DA of the display device 1 includes a blue light-emitting element 5B (light-emitting element). The red light-emitting element 5R included in the red subpixel RSP includes an anode which is the lower electrode 22, a laminated film 24R including a red light-emitting layer, and a cathode which is the upper electrode 25. The green light-emitting element 5G included in the green subpixel GSP includes an anode which is the lower electrode 22, a laminated film 24G including a green light-emitting layer, and a cathode which is the upper electrode 25. The blue light-emitting element 5B included in the blue subpixel BSP includes an anode which is the lower electrode 22, a laminated film 24B including a blue light-emitting layer, and a cathode which is the upper electrode 25. In the display device 1 shown in Figure 2, we will explain using the example of a case where a laminated film 24R including a red light-emitting layer, a laminated film 24G including a green light-emitting layer, and a laminated film 24B including a blue light-emitting layer are provided for each subpixel of each color. However, we are not limited to this, and one or more layers, such as a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer, included in the laminated film 24R including the red light-emitting layer, the laminated film 24G including the green light-emitting layer, and the laminated film 24B including the blue light-emitting layer, may be provided as a common layer (one layer) for each of the red subpixel RSP, green subpixel GSP, and blue subpixel BSP.

[0022] 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.

[0023] The barrier layer 3 is a layer that prevents foreign substances such as water and oxygen from entering the transistor TR, the red light-emitting element 5R, the green light-emitting element 5G, and the blue 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] The planarization film 21 can be made of, for example, a coatable organic material such as polyimide or acrylic.

[0029] The red light-emitting element 5R includes an anode which is the lower electrode 22 located above the planarization film 21, a laminated film 24R including a red light-emitting layer, and a cathode which is the upper electrode 25. The green light-emitting element 5G includes an anode which is the lower electrode 22 located above the planarization film 21, a laminated film 24G including a green light-emitting layer, and a cathode which is the upper electrode 25. The blue light-emitting element 5B includes an anode which is the lower electrode 22 located above the planarization film 21, a laminated film 24B including a blue light-emitting layer, and a cathode which is the upper electrode 25. The insulating bank 23 covering the edge of the anode which is the lower electrode 22 can be formed, for example, by coating an organic material such as polyimide or acrylic and then patterning it by photolithography. In this embodiment, the case in which the bank 23 is provided is described as an example, but the bank 23 may not be provided.

[0030] The sealing layer 6 is a light-transmitting film and can be composed of, for example, an inorganic sealing film 26 covering the cathode, which is the upper electrode 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 red light-emitting element 5R, the green light-emitting element 5G, and the blue light-emitting element 5B.

[0031] 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.

[0032] The functional film 39 is a film having at least one of, for example, an optical compensation function, a touch sensor function, and a protection function.

[0033] FIG. 3 is a cross-sectional view showing a schematic configuration of the red light-emitting element 5R provided in the display device 1 of Embodiment 1. FIG. 4 is a diagram showing a schematic configuration of the first charge transport layer 24ET provided between the red light-emitting layer 24REM of the red light-emitting element 5R shown in FIG. 3 and the cathode which is the upper electrode 25. FIG. 5 is a diagram showing an example of the alcohol protecting agent APA containing the alcohol protecting group APG and the desorbing group SEPG. FIG. 6 is a diagram showing a schematic configuration of another first charge transport layer 24ET' that can be provided between the red light-emitting layer 24REM of the red light-emitting element 5R shown in FIG. 3 and the cathode which is the upper electrode 25. FIG. 7 is a diagram showing a schematic configuration of the second charge transport layer 24HT provided between the red light-emitting layer 24REM of the red light-emitting element 5R shown in FIG. 3 and the anode which is the lower electrode 22. FIG. 8 is a diagram showing a schematic configuration of another second charge transport layer 24HT' that can be provided between the red light-emitting layer 24REM of the red light-emitting element 5R shown in FIG. 3 and the anode which is the lower electrode 22.

[0034] As shown in FIG. 3, the red light-emitting element 5R includes an anode which is the lower electrode 22, a cathode which is the upper electrode 25, a red light-emitting layer 24REM provided between the anode which is the lower electrode 22 and the cathode which is the upper electrode 25, a first charge transport layer 24ET which is a functional layer provided between the cathode which is the upper electrode 25 and the red light-emitting layer 24REM, and a second charge transport layer 24HT which is a functional layer provided between the anode which is the lower electrode 22 and the red light-emitting layer 24REM. Each of the first charge transport layer 24ET and the second charge transport layer 24HT which are functional layers contains a metal oxide and an alcohol protecting group APG. The functional layer means a layer provided between one of the cathode which is the upper electrode 25 and the anode which is the lower electrode 22 and the red light-emitting layer 24REM and containing at least a metal oxide and an alcohol protecting group APG, and any layer that performs a function may be used as long as it contains a metal oxide and an alcohol protecting group APG. For example, as in this embodiment, it may be the first charge transport layer 24ET that performs a charge (electron) transport function or the second charge transport layer 24HT that performs a charge (hole) transport function, or it may be an insulating layer that performs an insulating function, or a dipole forming layer that performs a function of forming a dipole. The insulating layer that performs an insulating function may be formed using, for example, silicon oxide (e.g., SiO ２ ), aluminum oxide (e.g., Al ２ O ３ ), magnesium oxide (e.g., MgO), yttrium oxide (e.g., Y ２ O ３ ). Also, the dipole forming layer that performs a function of forming a dipole may be, for example, molybdenum oxide (e.g., MoO ３ ), tungsten oxide (e.g., WO ３ ), magnesium oxide (e.g., MgO), aluminum oxide (e.g., Al ２ O ３ ), an oxide containing barium and titanium (e.g., BaTiO ３They may be formed using ). The first charge transport layer 24ET that performs the charge (electron) transport function described above, the second charge transport layer 24HT that performs the charge (hole) transport function, the insulating layer and the dipole forming layer can each be formed with an optimal film thickness according to their purpose, and generally, they can suitably perform the above-described functions with a film thickness of 1 nm or more and 10 nn or less.

[0035] In this embodiment, the first charge transport layer 24ET and the second charge transport layer 24HT in the red light-emitting element 5R are provided as functional layers containing a metal oxide and an alcohol protective group APG, as an example. However, the embodiment is not limited to this, and one of the first charge transport layer 24ET and the second charge transport layer 24HT may be provided as a functional layer containing a metal oxide and an alcohol protective group APG, while the other of the first charge transport layer 24ET and the second charge transport layer 24HT may be provided as a layer that does not contain at least one of the metal oxide and the alcohol protective group APG. Furthermore, in the red light-emitting element 5R, both the first charge transport layer 24ET and the second charge transport layer 24HT may be provided as layers that do not contain at least one of the metal oxide and the alcohol protective group APG, and for example, at least one of the insulating layer that performs the insulating function described above and the dipole forming layer that performs the function of forming a dipole may be provided as a functional layer containing a metal oxide and an alcohol protective group APG. As described above, the red light-emitting element 5R only needs to have a functional layer containing a metal oxide and an alcohol protecting group APG between one of the cathodes (upper electrode 25) and the anodes (lower electrode 22) and the red light-emitting layer 24REM. For example, one or more of the first charge transport layer 24ET, the second charge transport layer 24HT, the insulating layer that performs the insulating function described above, and the dipole forming layer that performs the dipole forming function described above may be provided as a functional layer containing a metal oxide and an alcohol protecting group APG.

[0036] As shown in FIG. 4, the first charge transport layer 24ET provided between the red light-emitting layer 24REM of the red light-emitting element 5R and the cathode as the upper electrode 25 contains a metal oxide and an alcohol protecting group APG. In the present embodiment, as an example, the case where electron-transporting metal oxide nanoparticles ETNP are used as the metal oxide contained in the first charge transport layer 24ET will be described, but it is not limited thereto. As shown in FIG. 6, the metal oxide contained in the first charge transport layer 24ET' provided between the red light-emitting layer 24REM of the red light-emitting element 5R and the cathode as the upper electrode 25 may be an electron-transporting metal oxide film ETBL.

[0037] In the present embodiment, as an example, the case where magnesium zinc oxide nanoparticles are used as the electron-transporting metal oxide nanoparticles ETNP will be described, but it is not limited thereto. For example, zinc oxide nanoparticles may be used, or nanoparticles of a metal oxide containing at least one of Zn, Mg, Ti, Sn, W, Ta, Ba, Zr, Al, Y, and Hf may be used. The particle size of the electron-transporting metal oxide nanoparticles ETNP is not particularly limited, and may be, for example, an electron-transporting metal oxide film ETBL in which an electron-transporting metal oxide is continuously formed, like the metal oxide contained in the first charge transport layer 24ET'. The electron-transporting metal oxide film ETBL can be formed using the same material as the material forming the electron-transporting metal oxide nanoparticles ETNP.

[0038] In the present embodiment, the first charge transport layer 24ET is composed of only an electron transport layer, and the case where the first charge transport layer 24ET is in contact with the red light-emitting layer 24REM will be described as an example, but it is not limited thereto. The first charge transport layer 24ET may be composed of at least one of an electron transport layer and an electron injection layer.

[0039] As shown in Figure 7, the second charge transport layer 24HT provided between the red light-emitting layer 24REM and the anode, which is the lower electrode 22 of the red light-emitting element 5R, contains a metal oxide and an alcohol protecting group APG. In this embodiment, the case in which hole-transporting metal oxide nanoparticles HTNP are used as the metal oxide contained in the second charge transport layer 24HT is described as an example, but it is not limited to this, and as shown in Figure 8, the metal oxide contained in the second charge transport layer 24HT' provided between the red light-emitting layer 24REM and the anode, which is the lower electrode 22 of the red light-emitting element 5R may be a hole-transporting metal oxide film HTBL.

[0040] In this embodiment, the use of nickel oxide nanoparticles as hole-transporting metal oxide nanoparticles (HTNPs) is described as an example, but the invention is not limited thereto. For example, nanoparticles of metal oxides containing at least one of Ni, Mg, Mo, Cu, Co, Cr, and Ti may be used. The particle size of the hole-transporting metal oxide nanoparticles (HTNPs) is not particularly limited, and may be a hole-transporting metal oxide film (HTBL), which is a film in which hole-transporting metal oxides are continuously formed, such as the metal oxide contained in the second charge transport layer 24HT'. The hole-transporting metal oxide film (HTBL) can be formed using the same material as the material used to form the hole-transporting metal oxide nanoparticles (HTNPs).

[0041] In this embodiment, the second charge transport layer 24HT is composed solely of a hole transport layer, and the second charge transport layer 24HT is in contact with the red light-emitting layer 24REM. This is described as an example, but the embodiment is not limited to this, and the second charge transport layer 24HT may be composed of at least one of a hole transport layer and a hole injection layer.

[0042] Although not illustrated, in metal oxide layers that do not contain alcohol-protecting groups (APG), such as metal oxides in charge transport layers that do not contain alcohol-protecting groups (APG), a large number of hydroxyl groups (alcohol groups) remain. This can lead to problems such as adverse effects on the light-emitting layer or the occurrence of defect emission in charge transport layers that do not contain alcohol-protecting groups (APG). Furthermore, if the light-emitting layer contains quantum dots, the large number of hydroxyl groups (alcohol groups) in the metal oxides in the charge transport layers that do not contain alcohol-protecting groups (APG) can degrade the quantum dots or prevent them from emitting light. Note that hydroxyl groups are present on the surface of metal oxides. For example, in the formation process of a bulk film containing metal oxides, hydroxyl groups are added to the outermost surface of the bulk film by moisture in the air during exposure to air and by materials that form hydroxyl groups in the precursor solution. Also, in the process of synthesizing nanoparticles containing metal oxides, hydroxyl groups are added to the surface of the nanoparticles by moisture in the air during exposure to air and by materials that form hydroxyl groups in the solution during nanoparticle synthesis. Therefore, in this embodiment, as described above, the red light-emitting element 5R is provided with a functional layer containing a metal oxide and an alcohol protecting group APG between one of the upper electrode 25 (cathode) and the lower electrode 22 (anode) and the red light-emitting layer 24REM, thereby suppressing adverse effects on the red light-emitting layer 24REM and the occurrence of defect emission in the functional layer containing the metal oxide and the alcohol protecting group APG. Furthermore, as in this embodiment, when the red light-emitting layer 24REM contains quantum dots, degradation of the quantum dots and a decrease in the luminescence efficiency of the quantum dots can be suppressed. In addition, when a metal oxide layer without an alcohol protecting group APG and a light-emitting layer are adjacent, for example, in contact, the above-mentioned problems become more pronounced, so the effect of providing a functional layer containing a metal oxide and an alcohol protecting group APG is even greater.

[0043] The first charge transport layer 24ET provided in the red light-emitting element 5R shown in Figure 4 contains the electron-transporting metal oxide nanoparticles ETNP described above and an alcohol protecting group APG. The alcohol protecting group APG contained in the first charge transport layer 24ET caps the numerous hydroxyl groups (alcohol groups) present in the electron-transporting metal oxide nanoparticles ETNP, thereby reducing the number of hydroxyl groups (alcohol groups) in the electron-transporting metal oxide nanoparticles ETNP. Therefore, the red light-emitting element 5R equipped with the first charge transport layer 24ET can suppress adverse effects on the red light-emitting layer 24REM and the occurrence of defect emission in the first charge transport layer 24ET.

[0044] The first charge transport layer 24ET' that can be provided in the red light-emitting element 5R shown in Figure 6 includes the electron-transporting metal oxide film ETBL described above and an alcohol-protecting group APG. The alcohol-protecting group APG contained in the first charge transport layer 24ET' caps the numerous hydroxyl groups (alcohol groups) present in the electron-transporting metal oxide film ETBL, thereby reducing the number of hydroxyl groups (alcohol groups) in the electron-transporting metal oxide film ETBL. Therefore, the red light-emitting element 5R equipped with the first charge transport layer 24ET' can suppress adverse effects on the red light-emitting layer 24REM and the occurrence of defect emission in the first charge transport layer 24ET'.

[0045] The second charge transport layer 24HT provided in the red light-emitting element 5R shown in Figure 7 contains the hole-transporting metal oxide nanoparticles HTNP described above and an alcohol-protecting group APG. The alcohol-protecting group APG contained in the second charge transport layer 24HT caps the numerous hydroxyl groups (alcohol groups) present in the hole-transporting metal oxide nanoparticles HTNP, thereby reducing the number of hydroxyl groups (alcohol groups) in the hole-transporting metal oxide nanoparticles HTNP. Therefore, the red light-emitting element 5R equipped with the second charge transport layer 24HT can suppress adverse effects on the red light-emitting layer 24REM and the occurrence of defect emission in the second charge transport layer 24HT.

[0046] The second charge transport layer 24HT' that can be provided in the red light-emitting element 5R shown in Figure 8 includes the hole-transporting metal oxide film HTBL described above and an alcohol-protecting group APG. The alcohol-protecting group APG contained in the second charge transport layer 24HT' caps the numerous hydroxyl groups (alcohol groups) present in the hole-transporting metal oxide film HTBL, thereby reducing the number of hydroxyl groups (alcohol groups) in the hole-transporting metal oxide film HTBL. Therefore, the red light-emitting element 5R equipped with the second charge transport layer 24HT' can suppress adverse effects on the red light-emitting layer 24REM and the occurrence of defect emission in the second charge transport layer 24HT'.

[0047] The alcohol protecting group APG contained in the first charge transport layer 24ET shown in Figure 4, the first charge transport layer 24ET' shown in Figure 6, the second charge transport layer 24HT shown in Figure 7, and the second charge transport layer 24HT' shown in Figure 8 are all part of an alcohol protective agent APA containing an alcohol protecting group APG and a leaving group SEPG, as shown in Figure 5. In this embodiment, the case in which the alcohol protecting agent APA is TPCl (Trityl Chloride) as shown in Figure 5, in which the alcohol protecting group APG is a trityl group and the leaving group SEPG is chlorine, will be described as an example, but the embodiment is not limited to this. The type of alcohol protective agent APA is not particularly limited as long as it contains a leaving group SEPG and an alcohol protecting group APG that can cap a hydroxyl group (alcohol group). As the alcohol protective agent APA, for example, a halide containing a trityl group as the alcohol protecting group APG and a halogen atom other than chlorine as the leaving group SEPG may be used, or a halide containing a trityl skeleton (a skeleton in which three phenyl groups are bonded to carbon) may be used, for example, any of Trityl Bromide, 4-Methoxytrityl Chloride, 4,4'-Dimethoxytrityl Chloride, 2-Chlorotrityl Chloride, 4,4',4''-Tris(benzoyloxy)trityl Bromide and Triphenyl chloro silane may be used.

[0048] Furthermore, as the alcohol protecting agent APA, for example, a silylating agent containing a silyl group as the alcohol protecting group APG, an acylating agent containing an acyl protecting group such as an acetyl group, a benzoyl group, and a pivaloyl group as the alcohol protecting group APG, an acetalizing agent containing an acetal as the alcohol protecting group APG, an alkoxymethylating agent containing an alkoxymethyl group as the alcohol protecting group APG, a Bocating agent containing a tert-butoxycarbonyl (Boc) group as the alcohol protecting group APG, a Bnating agent containing a benzyl (Bn) group as the alcohol protecting group APG, an allylating agent containing an allyl group as the alcohol protecting group APG, a Trocating agent containing a 2,2,2-trichloroethoxycarbonyl (Troc) group as the alcohol protecting group APG, and a sulfonylating agent containing various sulfonyl groups as the alcohol protecting group APG may be used.

[0049] As described above, the alcohol protective agent APA, which contains a leaving group SEPG and an alcohol protecting group APG that can cap hydroxyl groups (alcohol groups), differs from the self-assembled monolayer SSAM and PSAM shown in Figure 13, which are used to form self-assembled monolayers (SAMs), in the following respects. As shown in Figure 13, the Si-based self-assembled monolayer SSAM, which forms a self-assembled monolayer (SAM) on the surface of a metal oxide containing titanium (Ti) via step STEP b, contains an alkoxy group AKG, for example, Si-O-CH3, bonded to silicon, which has relatively high reactivity, in its side chain, and the P-based self-assembled monolayer PSAM, which forms a self-assembled monolayer (SAM) on the surface of a metal oxide containing titanium (Ti) via steps STEP Pa 1 to STEP Pa 5, contains a hydroxyl group (alcohol group) HG in its side chain. Self-assembled monolayer SSAMs react with each other through alkoxy groups (e.g., Si-OCH3) on their side chains, exhibiting a crosslinking reaction. Because self-assembled monolayer SSAMs can undergo crosslinking reactions and produce alcohols, they cannot act as alcohol protectants that terminate crosslinking reactions. On the other hand, alcohol protectants APAs cap the alkoxy groups (Si-O-CH3) and the Si-OH groups produced during their crosslinking reactions, as found in the self-assembled monolayer SSAMs, thus terminating the reaction. Therefore, alcohol protectants do not need to bond with each other to form a film, and thus do not contain relatively reactive groups such as hydroxyl groups (alcohol groups) or silicon-bonded alkoxy groups (e.g., Si-OCH3) within their molecules. The alkoxymethyl group (e.g., C-OCH3) found in alkoxymethylating agents, which are an example of the alcohol protectants APAs mentioned above, has lower reactivity compared to the silicon-bonded alkoxy group AKG (e.g., Si-O-CH3) found in Si-based self-assembled monolayer SSAMs. In other words, self-assembled membranes (SAMs) contain highly reactive alkoxy groups in their side chains, and cross-linking reactions occur between these side chains.On the other hand, the alcohol protective agent APA used in this embodiment, such as an alkoxymethylating agent, does not need to undergo crosslinking reactions between its side chains due to its role. In fact, if crosslinking reactions between the side chains were to occur, the objective of terminating the desired reactive group would not be achieved. Therefore, it contains a less reactive functional group in its side chain.

[0050] In this embodiment, we will describe, as an example, the case in which each of the first charge transport layers 24ET shown in Figure 4, the first charge transport layer 24ET' shown in Figure 6, the second charge transport layer 24HT shown in Figure 7, and the second charge transport layer 24HT' shown in Figure 8 each contains both an alcohol protective agent APA containing an alcohol protective group APG and a leaving group SEPG, and an alcohol protective group APG bonded to a metal oxide (any of electron-transporting metal oxide nanoparticles ETNP, electron-transporting metal oxide film ETBL, metal oxide nanoparticles HTNP, and metal oxide film HTBL). However, we are not limited to this, and may contain only one of the alcohol protective agent APA containing an alcohol protective group APG and a leaving group SEPG, or an alcohol protective group APG bonded to a metal oxide. The bonding of the alcohol protecting group APG to the metal oxide can be confirmed by one or a combination of the following methods: infrared spectroscopy (IR spectroscopy), Raman spectroscopy, X-ray absorption fine structure spectroscopy (XAFS), X-ray photoelectron spectroscopy (XPS), nuclear magnetic resonance spectroscopy (NMR), electron spin resonance (ESR), and time-of-flight secondary ion mass spectrometry (TOF-SIMS). Note that for alcohol protective agents APA containing both the alcohol protecting group APG and the leaving group SEPG, energy must be supplied to allow the hydroxyl group in the metal oxide to react with the alcohol protecting group APG. Depending on the type of alcohol protective agent APA used, additional energy supply may be required to separate the alcohol protective agent APA into the alcohol protecting group APG and the leaving group SEPG. If the alcohol protective agent APA reacts with the hydroxyl group in the metal oxide without separating into the alcohol protecting group APG and the leaving group SEPG, then additional energy supply is not necessary. Furthermore, the energy required to react the hydroxyl groups contained in the metal oxide with the alcohol protecting group APG, and the energy required to separate the alcohol protecting agent APA into the alcohol protecting group APG and the leaving group SEPG, can be performed in a single step using the higher energy supply. As described above, hydroxyl groups (alcohol groups) contained in metal oxides can be capped with the alcohol protecting group APG.Even when the first charge transport layer 24ET shown in Figure 4, the first charge transport layer 24ET' shown in Figure 6, the second charge transport layer 24HT shown in Figure 7, and the second charge transport layer 24HT' shown in Figure 8 each contain only the alcohol protective agent APA, which includes the alcohol protecting group APG and the leaving group SEPG, the effect of reducing the hydroxyl groups (alcohol groups) contained in the metal oxide can be obtained by providing energy to react the hydroxyl groups contained in the metal oxide with the alcohol protecting group APG, and, if necessary, providing the additional energy described above.

[0051] Each of the following charges is present: the first charge transport layer 24ET shown in Figure 4, the first charge transport layer 24ET' shown in Figure 6, the second charge transport layer 24HT shown in Figure 7, and the second charge transport layer 24HT' shown in Figure 8. Each of these layers contains an alcohol protecting group APG bonded to a metal oxide (either electron-transporting metal oxide nanoparticles ETNP, electron-transporting metal oxide film ETBL, metal oxide nanoparticles HTNP, or metal oxide film HTBL). The alcohol protecting group APG bonded to the metal oxide is bonded to the metal oxide via an oxygen atom. Each of the first charge transport layers, 24ET shown in Figure 4, 24ET' shown in Figure 6, 24HT shown in Figure 7, and 24HT' shown in Figure 8, contains multiple alcohol protecting groups APG. Some of these APGs are bonded to metal oxides (either electron-transporting metal oxide nanoparticles ETNP, electron-transporting metal oxide films ETBL, metal oxide nanoparticles HTNP, or metal oxide films HTBL), while other APGs are bonded to leaving groups SEPG. Each of the first charge transport layers, 24ET shown in Figure 4, 24ET' shown in Figure 6, 24HT shown in Figure 7, and 24HT' shown in Figure 8, contains an excess of alcohol protective agent APA, which includes alcohol protecting groups APG and leaving groups SEPG. Thus, by leaving an excess of the alcohol protective agent APA in each of the first charge transport layers 24ET shown in Figure 4, the first charge transport layer 24ET' shown in Figure 6, the second charge transport layer 24HT shown in Figure 7, and the second charge transport layer 24HT' shown in Figure 8, it is possible to prevent the presence of alkoxy groups (for example, methoxy groups (-OCH)) in the metal oxides contained in each of the first charge transport layers 24ET shown in Figure 4, the first charge transport layer 24ET' shown in Figure 6, the second charge transport layer 24HT shown in Figure 7, and the second charge transport layer 24HT' shown in Figure 8 from being mediated by alkoxy groups (for example, methoxy groups (-OCH)) ３ Even if the hydroxyl group (alcohol group) changes over time, the remaining unactivated alcohol protective agent APA in the surrounding area can act to suppress the change over time.

[0052] It is preferable to cap the numerous hydroxyl groups (alcohol groups) present in the metal oxide contained in the functional layer using the alcohol protecting group APG, thereby reducing the number of hydroxyl groups (alcohol groups) remaining in the metal oxide contained in the functional layer as much as possible. Therefore, ((amount of hydroxyl groups) / (amount of metal element)) × 100 [%] in the functional layer is preferably 1 [%] or more and 200 [%] or less, more preferably 1 [%] or more and 150 [%] or less, more preferably 1 [%] or more and 100 [%] or less, even more preferably 1 [%] or more and 50 [%] or less, even more preferably 1 [%] or more and 25 [%] or less, and most preferably 1 [%] or more and 15 [%] or less. The lower limit of ((amount of hydroxyl groups) / (amount of metal element)) × 100 [%] in the functional layer may be 5 [%] or more. The value of ((amount of hydroxyl groups) / (amount of metal element)) × 100 [%] in the functional layer described above can be obtained by comparing it with detection unit quantities derived from the device, such as peak intensity, signal intensity, and count, which are obtained by measuring only the functional layer using the measuring device. The value of ((amount of hydroxyl groups) / (amount of metal element)) × 100 [%] in the functional layer may be the result of measurements taken over a cross section or region of a predetermined size that can reflect the overall state of each of the functional layers, for example, the first charge transport layer 24ET shown in Figure 4, the first charge transport layer 24ET' shown in Figure 6, the second charge transport layer 24HT shown in Figure 7, and the second charge transport layer 24HT' shown in Figure 8, or it may be the average value of the results of measurements taken over multiple different cross section or regions.

[0053] In this embodiment, the case in which the red light-emitting element 5R, green light-emitting element 5G, and blue light-emitting element 5B shown in Figure 2 are all QLEDs (quantum dot light-emitting diodes) will be described as an example, but the invention is not limited to this, and one or more of the red light-emitting element 5R, green light-emitting element 5G, and blue light-emitting element 5B may be QLEDs. For example, if one of the red light-emitting element 5R, green light-emitting element 5G, and blue light-emitting element 5B is a QLED, the remaining two may be OLEDs (organic light-emitting diodes), and for example, if two of the red light-emitting element 5R, green light-emitting element 5G, and blue light-emitting element 5B are QLEDs, the remaining one may be an OLED. Furthermore, the red light-emitting element 5R, green light-emitting element 5G, and blue light-emitting element 5B shown in Figure 2 may all be OLEDs (organic light-emitting diodes).

[0054] The red light-emitting element 5R shown in Figure 3 is a QLED, and therefore the red light-emitting layer 24REM provided by the red light-emitting element 5R includes quantum dots (not shown). The quantum dots may have, for example, a core structure, a core / shell structure, a core / shell / shell structure, or a shell structure with a continuously changing core / ratio. The shell structure may be a single layer, a multi-shell consisting of multiple layers containing different materials, or a giant shell with a thickness of 2 nm or more. It is preferable that the shell of the quantum dots included in the red light-emitting layer 24REM completely covers the core, but it may also be formed on a part of the core surface. The core of a quantum dot is, for example, a crystal of a Group II-VI semiconductor such as MgS, MgSe, MgTe, CaS, CaSe, CaTe, BaS, BaSe, BaTe, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, PbS, PbSe, HgS, HgSe, HgTe, a crystal of a Group III-V semiconductor such as GaAs, GaP, InN, InAs, InP, InSb, Ga ３ S ２ Ga ２ See ３ In ２ S ３ In ２ See ３Crystals 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 ３ It can be made of semiconductor crystals with a perovskite structure, etc. The shell of the quantum dot can be selected from the same group of materials as the material that constitutes the quantum dot core as described above, and it is preferable to select a material that has a lattice constant close to that of the material that constitutes the quantum dot core and a larger band gap than that of the material that constitutes the quantum dot core. When the red light-emitting element 5R is an OLED, the red light-emitting layer 24REM contains an organic light-emitting material.

[0055] The red light-emitting element 5R, green light-emitting element 5G, and blue light-emitting element 5B shown in Figures 2 and 3 may be either top-emission or bottom-emission types. The red light-emitting element 5R, green light-emitting element 5G, and blue light-emitting element 5B have a sequential stacking structure in which the cathode, which is the upper electrode 25, is positioned above the anode, which is the lower electrode 22. To make it a top-emission type, the anode, which is the lower electrode 22, should be made of an electrode material that reflects visible light, and the cathode, which is the upper electrode 25, should be made of an electrode material that transmits visible light. To make it a bottom-emission type, the anode, which is the lower electrode 22, should be made of an electrode material that transmits visible light, and the cathode, which is the upper electrode 25, should be made of an electrode material that reflects visible light. On the other hand, in the case of an inverted stack structure in which the anode, which is the upper electrode 25, is positioned above the cathode, which is the lower electrode 22, in order to make it a top emission type, the cathode, which is the lower electrode 22, should be made of an electrode material that reflects visible light and the anode, which is the upper electrode 25, should be made of an electrode material that transmits visible light. In order to make it a bottom emission type, the cathode, which is the lower electrode 22, should be made of an electrode material that transmits visible light and the anode, which is the upper electrode 25, should be made of an electrode material that reflects visible light.

[0056] The electrode material that reflects visible light is not particularly limited as long as it can reflect visible light and is conductive, but examples include metallic materials such as Al, Mg, Li, and Ag, or alloys of the metallic materials, or laminates of the metallic material and transparent metal oxides (e.g., indium tin oxide, indium zinc oxide, indium gallium zinc oxide, etc.), or laminates of the alloy and the transparent metal oxide.

[0057] On the other hand, the electrode material that transmits visible light is not particularly limited as long as it can transmit visible light and is conductive, but examples include transparent metal oxides (e.g., indium tin oxide, indium zinc oxide, indium gallium zinc oxide, etc.), thin films made of metal materials such as Al and Ag, or nanowires made of metal materials such as Al and Ag.

[0058] In this explanation, the red light-emitting element 5R is used as an example among the red light-emitting element 5R, green light-emitting element 5G, and blue light-emitting element 5B shown in Figure 2. However, the green light-emitting element 5G and blue light-emitting element 5B can also be configured in the same way as the red light-emitting element 5R.

[0059] Figure 9 shows the manufacturing process of DISPS2, a dispersion of metal oxide nanoparticles to which an alcohol protecting group APG is bonded. Figure 10 shows the process of forming the first charge transport layer 24ET shown in Figure 4 using DISPS2, a dispersion of metal oxide nanoparticles to which an alcohol protecting group APG is bonded, as shown in Figure 9.

[0060] The method for manufacturing the metal oxide layer, for example, the first charge transport layer 24ET shown in Figure 4, is as follows, as shown in Figure 9, the process is as follows: (S1) Prepare a dispersion of metal oxide nanoparticles containing electron-transporting metal oxide nanoparticles, for example, magnesium zinc oxide nanoparticles which are electron-transporting metal oxide nanoparticles ETNP, and a dispersion medium, by adding an alcohol protective agent APA containing an alcohol protective group APG to a dispersion of metal oxide nanoparticles DISPS1, which is an alcohol-transporting metal oxide nanoparticle ETNP, and an alcohol protective agent APA containing an alcohol protective group APG, and an electron-transporting metal oxide The present invention includes a step (S2) of imparting energy to a dispersion of metal oxide nanoparticles, which is an electron-transporting metal oxide nanoparticle (ETNP) of magnesium zinc oxide, an alcohol protective agent APA containing the alcohol protective group APG, and a dispersion medium, in order to react the hydroxyl groups (alcohol groups) contained in the nanoparticles of magnesium zinc oxide, which is an electron-transporting metal oxide nanoparticle (ETNP), with the alcohol protective group APG; and a step (as shown in Figure 10) of forming a first charge transport layer 24ET, which is a metal oxide layer containing the alcohol protective group APG, as shown in Figure 4, using the dispersion DISPS2 after the energy-imparting step (S2). In this embodiment, in the step of preparing the dispersion (S1), TPCl (Trityl Chloride) was used as the alcohol protective agent APA containing the alcohol protective group APG. Furthermore, the dispersion medium used in the step of preparing the dispersion (S1) is not particularly limited as long as it can well disperse the metal oxide nanoparticles and the alcohol protective agent APA and exhibits good coating characteristics during coating.

[0061] As shown in Figure 9, by the energy-transferring step (S2), a dispersion of metal oxide nanoparticles, DISPS2, can be obtained, which includes nanoparticles of metal oxide, for example, nanoparticles of magnesium zinc oxide, which are electron-transporting metal oxide nanoparticles ETNP, an alcohol-protecting group APG bonded to the nanoparticles of magnesium zinc oxide, which are electron-transporting metal oxide nanoparticles ETNP, and a dispersion medium. In the dispersion of metal oxide nanoparticles, DISPS2, the alcohol-protecting group APG is bonded to the nanoparticles of metal oxide, for example, the electron-transporting metal oxide nanoparticles ETNP, via an oxygen atom. In this embodiment, in the energy-transferring step (S2), irradiation with light in the wavelength range of 254 nm or more and less than 500 nm was performed. Light with wavelengths shorter than 254 nm is preferable not to use because it decomposes not only the target alcohol-protecting agent APA but also other organic materials. On the other hand, light with wavelengths longer than 500 nm is preferable not to use because it is in the visible light range and may be included in the lighting of the working environment in the manufacturing process, potentially making manufacturing difficult. The process is not limited to this, and in the step of imparting energy to the dispersion (S2), heat treatment may be performed on the dispersion instead of light irradiation, or light irradiation and heat treatment may be performed on the dispersion simultaneously or sequentially. When heat treatment is performed on the dispersion in the step of imparting energy to the dispersion (S2), it is preferable to perform the heat treatment on the dispersion at a temperature of 0°C or higher and less than 150°C. Depending on the type of alcohol protective agent APA used, if it is not cooled to a temperature lower than 0°C, the alcohol protective group APG may react with the hydroxyl group contained in the metal oxide nanoparticle ETNP, so the lower limit temperature for the heat treatment described above is set to 0°C or higher.

[0062] Up to this point, we have explained, as an example, the case in which, in the step of imparting energy to the dispersion (S2), at least one of light irradiation and heat treatment is performed to separate the alcohol protective agent APA into the alcohol protective group APG and the leaving group SEPG, and then the alcohol protective group APG reacts with the hydroxyl group contained in the metal oxide nanoparticle ETNP. However, we are not limited to this, and depending on the type of alcohol protective agent APA used, the alcohol protective agent APA may not separate into the alcohol protective group APG and the leaving group SEPG, and the alcohol protective group APG may react with the hydroxyl group contained in the metal oxide nanoparticle ETNP while remaining in the alcohol protective agent APA state. In such cases, in the step of imparting energy to the dispersion (S2), it is only necessary to impart energy to react the hydroxyl group contained in the metal oxide nanoparticle ETNP with the alcohol protective group APG.

[0063] The process of forming the first charge transport layer 24ET shown in Figure 4, which is a metal oxide layer containing an alcohol protecting group APG, using the dispersion DISPS2 after the energy transfer step (S2) shown in Figure 10, includes the steps of dropping the dispersion DISPS2 after the energy transfer step (S2) onto a laminated film in which, for example, a lower electrode 22, a second charge transport layer 24HT, and a red light-emitting layer 24REM are laminated (S3), coating the dropped dispersion DISPS2 onto the laminated film in which the lower electrode 22, the second charge transport layer 24HT, and the red light-emitting layer 24REM are laminated (S4), and heat treatment (S5). In this embodiment, the step (S4) of coating the dropped dispersion DISPS2 onto the laminated film in which the lower electrode 22, the second charge transport layer 24HT, and the red light-emitting layer 24REM are laminated is described using a spin coater as an example, but the embodiment is not limited to this, and the step (S4) may be performed using, for example, an inkjet method or a slit coater. Also, in this embodiment, the step (S5) of heat treatment is described using a case in which it is performed at 100°C for 30 minutes as an example, but the embodiment is not limited to this.

[0064] Furthermore, an alternative method for manufacturing the metal oxide layer, for example, the first charge transport layer 24ET shown in Figure 4, may include the following steps: forming a metal oxide layer in the same manner as steps (S3) and (S4) shown in Figure 10, using a metal oxide nanoparticle dispersion DISPS1 which contains metal oxide nanoparticles, for example, nanoparticles of magnesium zinc oxide, which are electron-transporting metal oxide nanoparticles ETNP, and a dispersion medium, to which an alcohol protective agent APA containing an alcohol protecting group APG is added; and step (S5) shown in Figure 10, which is an example of a step to impart energy to the metal oxide layer in order to react the hydroxyl groups contained in the metal oxide nanoparticles with the alcohol protecting group APG.

[0065] Figure 11 shows the process of forming the first charge transport layer 24ET shown in Figure 4 using DISPS1, a dispersion of metal oxide nanoparticles that does not contain the alcohol protective agent APA shown in Figure 9.

[0066] Another method for manufacturing a metal oxide layer, for example, the first charge transport layer 24ET shown in Figure 4, may include, as shown in Figure 11, the steps of forming a metal oxide layer containing a metal oxide using a dispersion of metal oxide nanoparticles DISPS1 that does not contain the alcohol protective agent APA shown in Figure 9 (S11 to S13); adding an alcohol protective agent APA containing an alcohol protective group APG to the metal oxide layer (S14); and, after the step of adding the alcohol protective agent APA (S14), imparting energy to the metal oxide layer to react the hydroxyl groups contained in the metal oxide with the alcohol protective groups (S15). Furthermore, after the step of imparting energy to the metal oxide layer (S15), a rinsing step (S16) may be performed to remove excess alcohol protecting groups APG and unseparated alcohol protective agent APA to obtain the first charge transport layer 24ET shown in Figure 4. Alternatively, the rinsing step (S16) may be omitted, and the first charge transport layer 24ET shown in Figure 4 may be obtained with excess alcohol protecting groups APG and unseparated alcohol protective agent APA remaining. Note that the steps of forming the metal oxide layer containing the metal oxide (S11 to S13) are the same as steps (S3), (S4), and (S5) shown in Figure 10, so their explanation is omitted here.

[0067] In this embodiment, in the step of adding an alcohol protective agent APA containing an alcohol protecting group APG to the metal oxide layer (S14), for example, the laminated film including the metal oxide layer formed by the step of forming a metal oxide layer containing a metal oxide (S11 to S13) is immersed in a solution APAS containing an alcohol protective agent APA prepared by adding TPCl (Trityl Chloride), which was used as the alcohol protective agent APA, to the solvent. However, the method is not particularly limited as long as the alcohol protective agent APA contained in the solution APAS can be added to the metal oxide layer formed by the step of forming a metal oxide layer containing a metal oxide (S11 to S13). For example, the solution APAS containing the alcohol protective agent APA may be dropped onto the metal oxide layer formed by the step of forming a metal oxide layer containing a metal oxide (S11 to S13). Note that the step of imparting energy to the metal oxide layer (S15) is the same as the step of imparting energy (S2) shown in Figure 9, so a detailed explanation thereof is omitted. In this embodiment, in the step of imparting energy to the metal oxide layer (S15), light irradiation was performed at room temperature (25°C) for 10 minutes, but it is not limited to this. As described above, in this embodiment, TPCl (Trityl Chloride) is used as the alcohol protective agent APA, and the alcohol protective group APG and the leaving group SEPG can be separated by light irradiation at room temperature (25°C) for 10 minutes, so that thermal damage to the layer below the first charge transport layer 24ET can be suppressed.

[0068] Figure 12 shows the process of forming the first charge transport layer 24ET' shown in Figure 6.

[0069] Another method for manufacturing a metal oxide layer, for example, the first charge transport layer 24ET' shown in Figure 6, may include the steps of: forming an electron-transporting metal oxide film ETBL shown in Figure 6, which is a metal oxide layer containing a metal oxide (S21); adding an alcohol protective agent APA containing an alcohol protecting group APG to the electron-transporting metal oxide film ETBL (S22); and, after the step of adding the alcohol protective agent APA (S22), imparting energy to the metal oxide layer to react the hydroxyl groups contained in the metal oxide with the alcohol protecting group APG (S23). Furthermore, after the energy transfer step (S23), a rinsing step (S24) may be performed to remove excess alcohol protecting group APG and unseparated alcohol protective agent APA to obtain the first charge transport layer 24ET' shown in Figure 6. However, the rinsing step (S24) may be omitted, and the first charge transport layer 24ET' shown in Figure 6 may be obtained with excess alcohol protecting group APG and unseparated alcohol protective agent APA remaining. Note that the step of adding alcohol protective agent APA (S22) and the energy transfer step (S23) are the same steps as the step of adding alcohol protective agent APA shown in Figure 11 (S14) and the energy transfer step (S2) shown in Figure 9, respectively, so their explanation will be omitted.

[0070] As described above, this embodiment has described a light-emitting element equipped with a functional layer containing a metal oxide and an alcohol protecting group, and a display device equipped with the light-emitting element, as examples, but is not limited thereto. For example, the invention of this disclosure can be suitably used in electronic devices such as solar cells and sensors equipped with a functional layer containing a metal oxide and an alcohol protecting group. Furthermore, the above-described dispersion of metal oxide nanoparticles and method for manufacturing the metal oxide layer can be suitably used not only in light-emitting elements and display devices equipped with the light-emitting element, but also, for example, in electronic devices such as solar cells and sensors equipped with a functional layer containing a metal oxide and an alcohol protecting group.

[0071] [Additional Notes] 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.

[0072] This disclosure can be used in light-emitting devices, display devices, dispersions of metal oxide nanoparticles, and methods for manufacturing metal oxide layers.

[0073] 1 Display device 4 Thin-film transistor layer 5R Red light-emitting element (light-emitting element) 5G Green light-emitting element (light-emitting element) 5B Blue light-emitting element (light-emitting element) 22 Lower electrode 23 Bank 24R Multilayer film including red light-emitting layer 24G Multilayer film including green light-emitting layer 24B Multilayer film including blue light-emitting layer 24REM Red light-emitting layer 24ET, 24ET' First charge transport layer (functional layer) 24HT, 24HT' Second charge transport layer (functional layer) 25 Upper electrode 26, 28 Inorganic encapsulation film 27 Organic film 39 Functional film APA Alcohol protective agent APG Alcohol protective group SEPG Leaving group ETNP Electron-transporting metal oxide nanoparticles ETBL Electron-transporting metal oxide film HTNP Hole-transporting metal oxide nanoparticles HTBL Hole-transporting metal oxide film DISPS1 Dispersion of metal oxide nanoparticles without alcohol-protecting agents: DISPS2 Dispersion of metal oxide nanoparticles with alcohol-protecting groups: APAS Solution containing alcohol-protecting agent APA PIX Pixel RSP Red subpixel GSP Green subpixel BSP Blue subpixel DA Display area NDA Border area

Claims

1. A light-emitting element comprising an anode, a cathode, a light-emitting layer provided between the anode and the cathode, and a functional layer provided between one of the anode and the cathode and the light-emitting layer, wherein the functional layer comprises a metal oxide and an alcohol protecting group.

2. The light-emitting element according to claim 1, wherein the alcohol protecting group is bonded to a leaving group.

3. The light-emitting element according to claim 1, wherein the alcohol protecting group is bonded to the metal oxide.

4. The light-emitting element according to claim 1, wherein the alcohol protecting group is bonded to the metal oxide via an oxygen atom.

5. A light-emitting element comprising an anode, a cathode, a light-emitting layer provided between the anode and the cathode, and a functional layer provided between one of the anode and the cathode and the light-emitting layer, wherein the functional layer comprises a first alcohol protecting group bonded to a leaving group and a second alcohol protecting group bonded to a metal oxide.

6. The light-emitting element according to claim 5, wherein the second alcohol protecting group is bonded to the metal oxide via an oxygen atom.

7. The light-emitting element according to any one of claims 1 to 6, wherein ((amount of hydroxyl groups) / (amount of metal element)) × 100 [%] in the functional layer is 1 [%] or more and 200 [%] or less.

8. The light-emitting element according to claim 7, wherein ((amount of hydroxyl groups) / (amount of metal element)) × 100 [%] in the functional layer is 1 [%] or more and 150 [%] or less.

9. The light-emitting element according to claim 8, wherein ((amount of hydroxyl groups) / (amount of metal element)) × 100 [%] in the functional layer is 1 [%] or more and 100 [%] or less.

10. The light-emitting element according to claim 9, wherein ((amount of hydroxyl groups) / (amount of metal element)) × 100 [%] in the functional layer is 1 [%] or more and 50 [%] or less.

11. The light-emitting element according to claim 10, wherein ((amount of hydroxyl groups) / (amount of metal element)) × 100 [%] in the functional layer is 1 [%] or more and 25 [%] or less.

12. The light-emitting element according to claim 11, wherein ((amount of hydroxyl groups) / (amount of metal element)) × 100 [%] in the functional layer is 1 [%] or more and 15 [%] or less.

13. The light-emitting element according to any one of claims 7 to 12, wherein ((amount of hydroxyl groups) / (amount of metal element)) × 100 [%] in the functional layer is 5 [%] or more.

14. The light-emitting element according to any one of claims 1 to 13, wherein the functional layer comprises nanoparticles of the metal oxide.

15. The light-emitting element according to any one of claims 1 to 14, wherein the light-emitting layer and the functional layer are in contact.

16. The light-emitting element according to any one of claims 1 to 15, wherein the functional layer is a first charge transport layer provided between the cathode and the light-emitting layer, or a second charge transport layer provided between the anode and the light-emitting layer.

17. The light-emitting element according to claim 16, wherein the metal oxide contained in the first charge transport layer includes at least one of Zn, Mg, Ti, Sn, W, Ta, Ba, Zr, Al, Y, and Hf.

18. The light-emitting element according to claim 16, wherein the metal oxide contained in the first charge transport layer is zinc oxide or magnesium zinc oxide.

19. The light-emitting element according to claim 16, wherein the metal oxide contained in the second charge transport layer includes at least one of Ni, Mg, Mo, Cu, Co, Cr, and Ti.

20. The light-emitting element according to claim 16, wherein the metal oxide contained in the second charge transport layer is nickel oxide.

21. The light-emitting element according to any one of claims 1 to 20, wherein the light-emitting layer includes quantum dots.

22. The light-emitting element according to any one of claims 1 to 4, wherein the alcohol protecting group is a trityl group.

23. The light-emitting element according to claim 5 or 6, wherein the first alcohol protecting group or the second alcohol protecting group is a trityl group.

24. A display device comprising a light-emitting element according to any one of claims 1 to 23.

25. A method for producing a metal oxide layer, comprising the steps of: forming a metal oxide layer containing a metal oxide; adding an alcohol protective agent containing an alcohol protecting group to the metal oxide layer; and, after the step of adding the alcohol protective agent, applying energy to the metal oxide layer to react the hydroxyl groups contained in the metal oxide with the alcohol protecting group.

26. A method for producing a metal oxide layer, comprising the steps of: preparing a dispersion of metal oxide nanoparticles comprising metal oxide nanoparticles, an alcohol protective agent containing an alcohol protecting group, and a dispersion medium; imparting energy to the dispersion to react the hydroxyl groups contained in the metal oxide nanoparticles with the alcohol protecting group; and forming a metal oxide layer containing an alcohol protecting group using the dispersion after the energy imparting step.

27. A method for producing a metal oxide layer, comprising the steps of: preparing a dispersion of metal oxide nanoparticles comprising metal oxide nanoparticles, an alcohol protective agent containing an alcohol protecting group, and a dispersion medium; forming a metal oxide layer using the dispersion; and imparting energy to the metal oxide layer to react the hydroxyl groups contained in the metal oxide nanoparticles with the alcohol protecting group.

28. A method for manufacturing a metal oxide layer according to any one of claims 25 to 27, wherein the energy application step is performed by heat treatment and light irradiation.

29. The method for producing a metal oxide layer according to any one of claims 25 to 28, wherein the alcohol protective agent is composed of an alcohol protecting group and a leaving group, and in the energy imparting step, the alcohol protecting group and the leaving group of the alcohol protective agent are separated.

30. A method for producing a metal oxide layer according to any one of claims 25 to 29, wherein the energy application step is performed at a temperature of 0°C or higher and less than 150°C.

31. The method for manufacturing a metal oxide layer according to any one of claims 25 to 30, wherein the energy application step involves irradiation with light in the wavelength range of 254 nm or more and less than 500 nm.

32. A dispersion of metal oxide nanoparticles, comprising metal oxide nanoparticles, an alcohol protecting group bonded to the metal oxide nanoparticles, and a dispersion medium.

33. The dispersion of metal oxide nanoparticles according to claim 32, wherein the alcohol protecting group is bonded to the metal oxide nanoparticles via an oxygen atom.

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