Production method for light-emitting element and use for same

Abstract

In the present invention, a quantum dot dispersion liquid containing quantum dots is applied upon an electrode (22) to form a quantum dot layer (24Rq, 24Gq, 24Bq), the quantum dot layer is immersed in a solution (24p) containing a precursor of a matrix to form a quantum dot layer (24Rqp, 24Gqp, 24Bqp) containing the precursor, and a light-emitting layer (24R1, 24G1, 24B1) containing the quantum dots and the matrix is formed by applying energy to the quantum dot layer.

Description

Light-emitting device manufacturing method and its use

[0001] The present disclosure relates to a method for manufacturing a light-emitting device and its use.

[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 much attention because of their ability to achieve low power consumption, thinness, high image quality, and the like.

[0003] For example, Patent Document 1 discloses an organic EL display panel characterized in that the electrical resistivity of regions corresponding to contact holes in an interlayer insulating film and regions corresponding to spaces between adjacent pixel electrodes is higher than that of other regions in the organic EL layer. Patent Document 1 also discloses a method of increasing the electrical resistivity by irradiating laser light onto regions other than the light-emitting region.

[0004] International Publication No. 2013 / 011599

[0005] The light-emitting device and its manufacturing method described in Patent Document 1 have the problem that while current is suppressed by increasing the resistance of the light-emitting layer (organic EL layer), voltage is applied to a region with high resistance, weakening carrier injection into the light-emitting layer. Therefore, while leakage current outside the light-emitting region is suppressed, the light-emitting efficiency of the light-emitting device is reduced. In other words, the manufacturing method of the light-emitting device described in Patent Document 1 does not suggest a manufacturing method of a light-emitting device that can increase the electrical conductivity of the light-emitting layer in the light-emitting region by exposure while decreasing the electrical conductivity of the light-emitting layer (quantum dot layer) in the non-light-emitting region.

[0006] There is also a need for a novel method for producing a light-emitting device that can stably and quickly form a light-emitting layer containing quantum dots.

[0007] The invention according to one embodiment of the present disclosure has been made in view of the above-mentioned problems, and its purpose is to provide a method for manufacturing a light-emitting element that has high luminous efficiency as a light-emitting element while suppressing leakage current outside the light-emitting region, or to provide a novel method for manufacturing a light-emitting element that can stably and quickly form a light-emitting layer containing quantum dots.

[0008] In order to solve the above problems, a method for manufacturing a light-emitting element according to an embodiment of the present disclosure is a method for manufacturing a light-emitting element including a light-emitting layer between a first electrode and a second electrode, the light-emitting layer including quantum dots and a matrix, the method including the steps of: applying a quantum dot dispersion including quantum dots and an organic ligand onto the first electrode to form a quantum dot layer; and immersing the quantum dot layer in a solution including a precursor of the matrix to form a quantum dot layer including the precursor; applying energy to at least a portion of the quantum dot layer including the precursor to form a light-emitting layer including the quantum dots and the matrix; and forming the second electrode on the light-emitting layer.

[0009] In order to solve the above problems, a method for manufacturing a light-emitting element according to one embodiment of the present disclosure is a method for manufacturing a light-emitting element including a light-emitting layer between a first electrode and a second electrode, the light-emitting layer including quantum dots and a matrix, the method including: forming a quantum dot layer by applying a quantum dot dispersion liquid including quantum dots and a precursor of the matrix onto the first electrode; forming the light-emitting layer from the quantum dot layer on the first electrode by irradiating energy toward the quantum dot layer on the first electrode; and forming the second electrode on the light-emitting layer, leaving the quantum dot layer on the outer periphery of the light-emitting layer.

[0010] In order to solve the above problems, a light-emitting device according to one embodiment of the present disclosure is a light-emitting device including a light-emitting layer between a first electrode and a second electrode, the light-emitting layer including quantum dots and a matrix, the light-emitting layer being formed on the first electrode and having a quantum dot layer surrounding the outer periphery of the light-emitting layer, the quantum dot layer including the quantum dots and a metal complex having a ligand, and the area density of the quantum dots in a layer cross-section of the light-emitting layer being greater than the area density of the quantum dots in a layer cross-section of the quantum dot layer.

[0011] It is possible to manufacture a light-emitting device that has high luminous efficiency as a light-emitting element while suppressing leakage current in areas other than the light-emitting region, or a light-emitting device in which a quantum dot-containing light-emitting layer can be rapidly formed.

[0012] 1 is a plan view showing a schematic configuration of a step of forming quantum dot layers 24Rq, 24Gq, and 24Bp in a precursor-containing solution 24p in the method for manufacturing the light-emitting element 5 of embodiment 1. FIG. 2 is a cross-sectional view showing a schematic configuration of a step of immersing quantum dot layers 24Rq, 24Gq, and 24Bp in a precursor-containing solution 24p in the method for manufacturing the light-emitting element 5 of embodiment 1. FIG. 3 is a cross-sectional view showing a schematic configuration of quantum dot layers 24Rqp, 24Gqp, and 24Bqp containing precursors formed by the method for manufacturing the light-emitting element 5 of embodiment 1. FIG. 4 is a cross-sectional view showing a schematic configuration of a step of exposing quantum dot layers 24Rqp, 24Gqp, and 24Bqp containing precursors in the method for manufacturing the light-emitting element 5 of embodiment 1. FIG. 5 is a cross-sectional view showing a schematic configuration of light-emitting layers 24R1, 24G1, and 24B1 formed from quantum dot layers 24Rqp, 24Gqp, and 24Bqp containing precursors in the method for manufacturing the light-emitting element 5 of embodiment 1. FIG. 6 is a top view showing a schematic configuration of the light-emitting element 5 of embodiment 1. 10 is a cross-sectional view showing a schematic configuration of a method for manufacturing a light-emitting element 5 according to embodiment 2. FIG. 11 is a cross-sectional view showing a schematic configuration of a method for manufacturing a light-emitting element 5a according to embodiment 3. FIG. 12 is a cross-sectional view showing a schematic configuration of a light-emitting element 5a according to embodiment 3. FIG. 13 is a cross-sectional view showing a schematic configuration of a light-emitting element 5a according to embodiment 3. FIG. 14 is a cross-sectional view showing a schematic configuration of a red light-emitting element provided in a display device of embodiment 3. FIG. 15 is a cross-sectional view showing a schematic configuration of a red light-emitting element provided in a display device. FIG. 16 is a cross-sectional view showing a schematic configuration of a light-emitting element 5b according to embodiment 4. FIG. 17 is a cross-sectional view showing a schematic configuration of a light-emitting element 5b according to embodiment 4. FIG. 18 is a plan view showing a schematic configuration of a display device 1 according to embodiment 5. FIG. 19 is a graph showing evaluation results of current density as an evaluation of electron injection properties between the light-emitting layer and the quantum dot layer in light-emitting elements formed as examples.

[0013] The embodiments of the present disclosure will be described as follows: For the sake of convenience, components having the same functions as those described in specific embodiments will be denoted by the same reference numerals, and their description may be omitted.

[0014] [Method for Manufacturing Light-Emitting Element (Embodiment 1)] A method for manufacturing a light-emitting element 5 according to an embodiment (Embodiment 1) of the present disclosure will be described with reference to FIGS. 1 shows a schematic configuration of a step of forming quantum dot layers 24Rq, 24Gq, and 24Bp in the manufacturing method of the light-emitting element 5 of this embodiment 1, FIG. 2 shows a schematic configuration of a step of immersing quantum dot layers 24Rq, 24Gq, and 24Bp in a solution 24p containing a precursor, FIG. 3 shows a schematic configuration of quantum dot layers 24Rqp, 24Gqp, and 24Bqp containing a precursor, FIG. 4 shows a schematic configuration of a step of exposing quantum dot layers 24Rqp, 24Gqp, and 24Bqp containing a precursor, FIG. 5 shows a schematic configuration of light-emitting layers 24R1, 24G1, and 24B1 formed from quantum dot layers 24Rqp, 24Gqp, and 24Bqp containing precursors, and FIG. 6 shows a schematic configuration of light-emitting layers 24R1, 24G1, and 24B1 formed from quantum dot layers 24Rqp, 24Gqp, and 24Bqp containing precursors. As shown in Figures 6 and 7, a method for manufacturing a light-emitting element 5 according to one embodiment of the present disclosure produces a light-emitting element 5 including light-emitting layers 24R1, 24G1, and 24B1 containing quantum dots and a matrix between a first electrode 22 and a second electrode 25.

[0015] As shown in FIG. 1, the method for manufacturing the light-emitting element 5 involves applying a quantum dot dispersion containing quantum dots and organic ligands to the first electrode 22 of the substrate 12 on which the hole transport layer (functional layer) 24H has been formed, followed by patterning to form quantum dot layers 24Rq, 24Gq, and 24Bq. Next, as shown in FIG. 2, the quantum dot layers 24Rq, 24Gq, and 24Bq are immersed in a precursor solution 24p to form quantum dot layers 24Rqp, 24Gqp, and 24Bqp containing a matrix precursor, as shown in FIG. 3. As shown in FIG. 4, the method for manufacturing the light-emitting element 5 involves applying energy to at least a portion of the ligand-exchanged quantum dot layers 24Rqp, 24Gqp, and 24Bqp to form light-emitting layers 24R1, 24G1, and 24B1 containing the quantum dots and the matrix, as shown in FIG. 5. This produces the light-emitting element 5 shown in FIGS. 6 and 7.

[0016] A method for manufacturing a light emitting device according to one embodiment includes a step of forming a bank 23 surrounding a first electrode 22 (FIG. 1).

[0017] A method for manufacturing a light-emitting device according to an embodiment includes forming a hole transport layer (functional layer) 24H on the first electrode 22, forming an electron transport layer (functional layer) 24E on the light-emitting layers 24R1, 24G1, and 24B1, and then forming the hole transport layer (functional layer) 24H on the light-emitting layers 24R1, 24G1, and 24B1. The patterning of the bank 23 surrounding the first electrode 22 (the bank forming step) and the patterning of the quantum dot layers 24Rq, 24Gq, and 24Bq for forming the light-emitting layers 24R1, 24G1, and 24B1 can be performed, for example, by a photolithography method in which, before the quantum dot layer forming step described below, a resist layer is formed on a substrate on which the first electrode is provided (the resist layer forming step), the resist layer is exposed to light to form a pattern having openings on the first electrode (the pattern forming step having openings on the first electrode), and the resist layer is peeled off after the light-emitting layer forming step (the resist layer peeling step).

[0018] A manufacturing method according to one embodiment will be described using an example of a light-emitting element 5 in which a hole transport layer 24H, light-emitting layers 24R1, 24G1, and 24B1, and an electron transport layer 24E are stacked in this order in the light-emitting region HR between the first electrode 22 and the second electrode 25 as shown in Figure 6.

[0019] The light-emitting element 5 includes light-emitting elements 5R, 5B, and 5G each including a first electrode 22 on a plurality of first electrodes 22 provided on a thin-film transistor layer 4 (described later) ( FIG. 6 ). In the light-emitting element 5, the first electrode 22 can be an anode, and the second electrode 25 can be a cathode.

[0020] 6, the thin film transistor layer 4 is formed with a first electrode 22 and a hole transport layer 24H, which are partitioned by a bank 23. A quantum dot layer is formed in a region HR partitioned by the bank 23.

[0021] The electrode material that reflects visible light and is used to form the first electrode 22 and / or the second electrode 25 is not particularly limited as long as it can reflect visible light and has conductivity. Examples of the electrode material that reflects visible light include metal materials such as Al, Cu, Au, Mg, Li, and 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.), and laminates of the alloys and the transparent metal oxides.

[0022] On the other hand, the electrode material that transmits visible light and is used to form the first electrode 22 and / or the second electrode 25 is not particularly limited as long as it can transmit visible light and has conductivity, and examples thereof 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, and nanowires made of metal materials such as Al and Ag.

[0023] The first and second electrodes can be formed by a general electrode formation method, such as a physical vapor deposition (PVD) method such as vacuum deposition, sputtering, EB deposition, or ion plating, or a chemical vapor deposition (CVD) method. The first and second electrodes can be patterned by, but not limited to, a photolithography method or an inkjet method.

[0024] The bank 23 surrounding the light-emitting layers 24R1, 24G1, and 24B1 can be manufactured by applying an organic material such as polyimide or acrylic and then patterning it by photolithography, for example.

[0025] The light-emitting element 5 may be a top-emission type or a bottom-emission type. To achieve a top-emission type with a forward stack structure, the anode (first electrode) may be formed from an electrode material that reflects visible light, and the cathode (second electrode) may be formed from an electrode material that transmits visible light. Conversely, to achieve a bottom-emission type, the cathode as the first electrode may be formed on the substrate from an electrode material that transmits visible light, and the anode as the second electrode may be formed from an electrode material that reflects visible light. Although the light-emitting element 5 having a forward stack structure will be described below, the light-emitting element may also have an inverted stack structure in which the cathode (first electrode), an electron transport layer as a functional layer, a light-emitting layer, a hole transport layer as a functional layer, and an anode (second electrode) are formed in this order on the substrate.

[0026] (Formation of Hole Transport Layer) The hole transport layer 24H is a layer that transports holes toward the light-emitting layer. Although not shown, the hole transport layer may be composed of multiple hole transport layers. When the light-emitting element has multiple hole transport layers, one of the hole transport layers may be referred to as a hole injection layer.

[0027] When the hole transport layer 24H is a hole injection layer, the hole injection material may be, for example, NiO, CuI, Cu ２ O, CoO, Cr ２ O ３ , CuAlS ２The hole injection material nanoparticles may have a thiol or amine as a ligand. These hole injection materials can be used in the formation of a hole transport layer as a dispersion.

[0028] The material used for the hole transport layer 24H is not particularly limited as long as it is a hole transport material that can stabilize the transport of holes to the light-emitting layers 24R1, 24G1, and 24B1. The hole transport material in the hole transport layer preferably has high hole mobility. Furthermore, the hole transport material is preferably a material (electron-blocking material) that can prevent electrons from migrating from the cathode from penetrating through the hole transport layer. This is because the recombination efficiency of holes and electrons in the light-emitting layers can be increased. The hole transport material is preferably a photosensitive hole transport material having a cationically polymerizable functional group such as an oxetane ring. Examples of the photosensitive hole transport material include N,N'-(4,4'-(cyclohexane-1,1-diyl)bis(4,1-phenylene))bis(N-(4-(6-(2-ethyloxetan-2-yloxy)hexyl)phenyl)-3,4,5-trifluoroaniline), N4,N4'-bis(4-(6-((3-ethyloxetan-3-yl)methoxy)hexyloxyphenyl)-N4,N4'-bis(4-methoxyphenyl)biphenyl-4,4'-diamine, and N4,N4'-bis(4-(6-((3-ethyloxetan-3-yl)methoxy)hexyl) Examples of the photosensitive hole transport material included in the hole transport layer include cationic polymerization using, for example, a photoacid generator. The hole transport layer may also include a product generated by exposure of the photoacid generator. Other examples of the hole transport material include poly-TPD, polyvinylcarbazole (PVK), and poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl))diphenylamine)] (TFB). These hole transport materials can be used to form the hole transport layer, for example, in the form of a dispersion or a solution.

[0029] The dispersion of the hole injection material and the dispersion of the hole transport material may contain, for example, a polar solvent such as ethanol. The hole transport layer may be formed by applying the dispersion onto the first electrode and the bank by a known method such as an ink-jet method, a spin coating method, or a dip coating method, and then drying the dispersion solvent, or by a known method such as a chemical vapor deposition method, depending on the type of the hole transport material.

[0030] 1, in the manufacturing method according to this embodiment, a quantum dot dispersion containing quantum dots (QDs) and organic ligands is applied by a known method such as inkjet printing or spin coating (a quantum dot layer forming step). This forms quantum dot layers 24Rq, 24Gq, and 24Bq. The quantum dots (QDs) contained in each of the quantum dot layers 24Rq, 24Gq, and 24Bq can emit light of different wavelengths.

[0031] The quantum dots (QDs) included in the quantum dot layers 24Rq, 24Gq, and 24Bq may have, for example, a core structure, a core / shell structure, a core / shell / shell structure, or a shell structure with a continuously varying core / shell ratio. The shell may partially cover the core, but it is preferable for the shell to completely cover the core. The core material of the quantum dot QD1 may be, for example, a II-VI group semiconductor crystal such as MgS, MgSe, MgTe, CaS, CaSe, CaTe, BaS, BaSe, BaTe, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, PbS, PbSe, HgS, HgSe, or HgTe; a III-V group semiconductor crystal such as GaAs, GaP, InN, InAs, InP, or InSb; or Ga ３ S ２ , Ga ２ Se ３ , In ２ S ３ , In ２ Se ３ Crystals of III-VI group semiconductors such as CuInGaS, AgInGaS, CuInGaS, AgInGaZnS, CuInGaSe, AgInGaSe, etc., crystals of I-III-VI group semiconductors such as C and Si, crystals of IV group semiconductors such as CsPbI ３ , CsPbBr３ , CsPbCl ３ The shell material may be composed of a semiconductor crystal having a perovskite structure such as ZnSe or ZnSeTe. The shell material is preferably selected from the same material group as the core material, has a lattice constant close to that of the core material, and has a larger band gap than the core material. It is preferable to use, as the quantum dot (QD), for example, a material having 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)), but this is not limited thereto. For example, ZnSe or ZnSeTe may be used as the core material, and these are preferably used in particular for the blue subpixel.

[0032] The quantum dot (QD) refers to a dot having a maximum width of 100 nm or less. The shape of the quantum dot (QD) is not particularly limited as long as it satisfies the above maximum width, and is not limited to a spherical three-dimensional shape (circular cross-sectional shape). For example, it may have a polygonal cross-sectional shape, a rod-like three-dimensional shape, a branch-like three-dimensional shape, a three-dimensional shape with an uneven surface, or a combination thereof.

[0033] The quantum dot dispersion liquid contains a low-polarity solvent (also called a quantum dot dispersion medium) such as n-hexane, n-octane, n-decane, toluene, or phenylcyclohexane, and may contain a dispersion material mixed in. The quantum dot dispersion liquid may also contain a solvent such as dimethylformamide (DMF) or dimethyl sulfoxide (DMSO).

[0034] As described below, before immersion in solution 24p, the quantum dots (QDs) contained in the quantum dot (QD) dispersion are coordinated with organic ligands. The organic ligands may be known capping ligands, such as oleylamine, octanethiol, dodecanethiol, tributylphosphine oxide, trioctylphosphine, and oleic acid. Among these, octanethiol, dodecanethiol, trioctylphosphine, and oleic acid are more preferred. Organic ligands such as octanethiol exhibit surface activity and are therefore soluble in both polar and low-polarity solvents. Furthermore, when octanethiol is used as the organic ligand, the thiol group of octanethiol can be efficiently coordinated to the shell of the quantum dots (QDs) (e.g., zinc sulfide (ZnS)). Quantum dots (QDs) with octanethiol coordinated to the surface tend to be difficult to disperse in polar solvents because the low-polarity alkyl chain of octanethiol is coordinated toward the surface. In addition, the quantum dots (QDs) contained in the quantum dot (QD) dispersion may have halogen ions coordinated thereto.

[0035] The quantum dot dispersion liquid may be applied by, for example, spin coating or inkjet printing to form a quantum dot layer, and by applying different coatings to each subpixel, quantum dot layers containing different quantum dots (QDs) can be formed. The application of different coatings to each subpixel may be performed by, for example, patterning using an inkjet method or photolithography.

[0036] After the quantum dot dispersion liquid is applied, the solvent contained in the quantum dot dispersion liquid may be dried and removed by heating and / or reducing pressure, thereby removing the solvent from the quantum dot layers 24Rq, 24Gq, and 24Bq.

[0037] [Precursor Solution 24p] As shown in FIG. 2, in the manufacturing method according to this embodiment, the thin film transistor layer 4 on which the quantum dot layers 24Rq, 24Gq, and 24Bq have been formed is immersed in a precursor solution 24p. The precursor solution 24p contains a metal complex or a semimetallic compound as a matrix precursor. Here, the semimetallic element includes boron (B), silicon (Si), arsenic (As), antimony (Sb), tellurium (Te), or selenium (Se). As a result, as shown in FIG. 3, the quantum dot layers 24Rq, 24Gq, and 24Bq formed on the thin film transistor layer 4 are (i) infiltrated with the precursor contained in the precursor solution 24p, and / or (ii) the organic ligands of the quantum dots (QDs) of the quantum dot layers 24Rq, 24Gq, and 24Bq are exchanged with ligands of the precursor or the precursor itself, thereby forming quantum dot layers 24Rqp, 24Gqp, and 24Bqp. The exchange of organic ligands possessed by quantum dots (QDs) with ligands possessed by precursors may be simply referred to as ligand exchange.

[0038] The quantum dot layers 24Rq, 24Gq, and 24Bq are preferably immersed in the precursor solution 24p by a dip coating method, but this is not limited thereto, and any known method such as a spin coating method or an inkjet method may be used.

[0039] (Metal Complex) The precursor contained in the precursor solution 24p is preferably a metal complex. The metal complex is preferably a metal complex having a ligand selected from xanthogenic acid, thiocarboxylic acid, and thiourea. This allows a metal sulfide semiconductor derived from the formed metal complex to be formed as a matrix in the light-emitting layer by applying energy as described below. At this time, the metal sulfide semiconductor can be formed in the light-emitting layer while forming a metal sulfide shell with quantum dots (QDs) as its core.

[0040] When immersed in a solution 24p containing a metal complex as a precursor, quantum dot layers 24Rqp, 24Gqp, and 24Bqp are formed in which the organic ligands of the quantum dots (QDs) are ligand-exchanged with the metal complex.

[0041] From the viewpoint 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 tin (Sn), magnesium (Mg), or zinc (Zn), and still more preferably zinc (Zn).

[0042] The xanthogenic acid, thiocarboxylic acid, and thiourea selected as the ligand of the metal complex preferably have an alkyl group having 1 to 5 carbon atoms. This allows a matrix derived from the metal complex to be formed with lower energy. More specific examples of the ligand of the metal complex include xanthogenic acids such as methylxanthogenic acid, ethylxanthogenic acid, n-propylxanthogenic acid, and i-propylxanthogenic acid; thiocarboxylic acids such as methylthiocarboxylic acid, ethylthiocarboxylic acid, n-propylthiocarboxylic acid, and i-propylthiocarboxylic acid; N-methylthiourea, 1,3-dimethylthiourea, N,N'-dimethylthiourea, tetramethylthiourea, and thioacetamide. Among these, from the viewpoint of decomposition temperature, the ligand is preferably selected from xanthogenic acid, and the metal complex preferably contains zinc methylxanthogenate, zinc ethylxanthogenate, or zinc isopropylxanthogenate.

[0043] The metal complex solution preferably contains a proton-donating solvent, and examples of the solvent (also referred to as a precursor solvent) include alcohol solvents such as methanol, ethanol, isopropyl alcohol, etc. Examples of the precursor solvent include highly polar solvents such as N-methylformamide (NMF), dimethylformamide (DMF), tetrahydrofuran (THF), and dimethyl sulfoxide (DMSO).

[0044] The metal complex solution 24p may contain an organic acid such as formic acid or acetic acid as a proton-donating compound, which can promote the exchange between the organic ligands coordinated to the quantum dots (QDs) and the ligands of the metal complex.

[0045] The concentration of the ligand contained in the metal complex solution 24p should not be limited, regardless of whether the ligand of the metal complex is coordinated to a metal atom, but may be, for example, 47.5 mmol / L to 62.5 mmol / L in the metal complex solution, and preferably 57.5 mmol / L to 62.5 mmol / L, which allows the organic ligand coordinated to the quantum dots (QDs) to be more quickly exchanged for the ligand possessed by the metal complex.

[0046] One of the advantages of the method for manufacturing an emitting layer according to one embodiment is that by immersing the quantum dot layer in a solution 24p of a metal complex, the organic ligands of the quantum dots can be stably and quickly exchanged with the ligands of the metal complex.

[0047] [1-1-2] Silicon Compound The precursor contained in the precursor solution 24p is preferably a silicon compound. The silicon compound is preferably an organosilane compound, and by applying energy as described below, an oxide semiconductor derived from the silicon compound can be formed as a matrix in the light-emitting layer to be formed.

[0048] The silicon compound is preferably an organosilane compound having at least one alkyl group (alkoxysilyl group) having 1 to 5 carbon atoms, and the silicon compound may be an organosilane compound having a polar group such as a thiol group, a hydroxyl group, or an amino group, and may be selected from, for example, tetramethyl orthosilicate, tetraethyl orthosilicate, trimethoxyphenylsilane, diphenylsilanediol, 3-mercaptopropyltrimethoxysilane, or 3-mercaptopropyltriethoxysilane. For example, the silicon compound may have a polar group such as a thiol group, thereby forming quantum dot layers 24Rqp, 24Gqp, and 24Bqp in which the organic ligands contained in quantum dot layers 24Rq, 24Gq, and 24Bq are replaced with the silicon compound itself (precursor itself).

[0049] For example, the silicon compound may be an organic silane compound having at least one alkyl group (alkoxysilyl group) having 1 to 5 carbon atoms, such as tetramethyl orthosilicate or tetraethyl orthosilicate, to form quantum dot layers 24Rqp, 24Gqp, and 24Bqp permeated with the organic silane compound.

[0050] The silicon compound solution 24p preferably contains a proton-donating solvent, and examples of the solvent include alcohol solvents and highly polar solvents, similar to the precursor solvents described above. When the silicon compound is liquid, a liquid silicon compound that does not contain a proton-donating solvent may be used as a precursor, and the quantum dot layers 24Rq, 24Gq, and 24Bq may be immersed in the precursor solution 24p. When a liquid silicon compound that does not contain a solvent is used as a precursor, the quantum dot layers 24Rq, 24Gq, and 24Bq formed on the substrate 12 may be washed with a proton-donating solvent and then immersed in the liquid silicon compound.

[0051] The silicon compound solution 24p may contain an organic acid such as formic acid or acetic acid as a proton-donating compound (acid compound). This can promote the exchange of the organic ligands coordinated to the quantum dots (QDs) with the ligands of the metal complex. This can also promote the dehydration condensation of the silicon compound, facilitating the formation of a matrix of a semimetallic oxide semiconductor.

[0052] The concentration of the silicon compound contained in the silicon compound solution 24p may be, for example, 47.5 mmol / L to 62.5 mmol / L, and preferably 57.5 mmol / L to 62.5 mmol / L, which allows the organic ligands coordinated to the quantum dots (QDs) to be more quickly replaced with silicon compounds having polar groups.

[0053] 4, energy may be applied to the formed quantum dot layers 24Rqp, 24Gqp, and 24Bqp after immersion in a precursor solution 24p of the quantum dot layers 24Rq, 24Gq, and 24Bqp. This allows light-emitting layers 24R1, 24G1, and 24B1 to be formed from at least a portion of the quantum dot layers 24Rqp, 24Gqp, and 24Bqp (a step of forming a light-emitting layer).

[0054] The energy imparted to the quantum dot layers 24Rqp, 24Gqp, and 24Bqp may be imparted by heat treatment or exposure (light irradiation), and is preferably imparted by exposure (light irradiation).

[0055] When energy is applied to the quantum dot layers 24Rqp, 24Gqp, and 24Bqp by heat treatment, the temperature can be appropriately designed depending on the type of precursor used and should not be limited, but is preferably in the range of 50°C to 200°C, and more preferably in the range of 100°C to 150°C.

[0056] When energy is imparted to the quantum dot layers 24Rqp, 24Gqp, and 24Bqp by exposure, the exposure conditions may be appropriately designed depending on the type of precursor used and should not be limited. For example, examples of light for exposing the quantum dot layers 24Rqp, 24Gqp, and 24Bqp include ultraviolet light with a wavelength of approximately 150 to 450 nm and electron beams. The 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, or may be an excimer laser (wavelength 150 to 248 nm). For example, when the ligand contained in the quantum dot layers 24Rqp, 24Gqp, and 24Bqp is xanthogenic acid, it is preferable to irradiate with ultraviolet light with a wavelength of 290 to 300 nm. The exposure dose is not limited, but may be, for example, 1 mJ / cm. ２ ~1000mJ / cm ２ This allows the quantum dot layers 24Rqp, 24Gqp, and 24Bqp to be sufficiently exposed, and allows a matrix to be formed from the precursors contained in the quantum dot layers 24Rqp, 24Gqp, and 24Bqp.

[0057] As shown in FIG. 4 , by exposing the quantum dot layer stacked on the first electrode 22, light-emitting layers 24R1, 24G1, and 24B1 with a matrix can be formed so as to be stacked on the first electrode 22, as shown in FIG. 5 . Furthermore, quantum dot layers 24Rqp, 24Gqp, and 24Bqp can be left on the bank 23 so as to surround the outer periphery of the light-emitting layer with a matrix. When the quantum dot layers 24Rqp, 24Gqp, and 24Bqp contain a metal complex, a matrix of a metal sulfide semiconductor derived from the metal complex is formed in the light-emitting layers 24R1, 24G1, and 24B1. When the quantum dot layers 24Rqp, 24Gqp, and 24Bqp contain a silicon compound, a matrix of an oxide semiconductor derived from the silicon compound is formed in the light-emitting layers 24R1, 24G1, and 24B1. In contrast, the quantum dot layers 24Rqp, 24Gqp, and 24Bqp contain precursors that did not contribute to the formation of the matrix and organic ligands that have been exchanged with the precursor ligands and dissociated from the quantum dots (QDs).Some of the organic ligands that were coordinated to the quantum dots may remain in the light-emitting layers 24R1, 24G1, and 24B1.

[0058] The light-emitting layer is a layer containing quantum dots (QDs) and a matrix formed from precursors, and the quantum dot layer is a layer containing quantum dots (QDs) and precursors that did not contribute to the formation of the matrix.

[0059] [Formation of Electron Transport Layer and Second Electrode] The electron transport layer 24E is a layer that transports electrons from the cathode side toward the light-emitting layer. Although not shown, an electron injection layer may be formed between the electron transport layer and the cathode. Examples of electron injection materials contained in the electron injection layer include LiF.

[0060] The electron transporting material contained in the composition used to form the electron transport layer 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 examples thereof include ZnO, ZnS, ZrO, MgZnO, AlZnO, and TiO. ２These nanoparticles may have a ligand such as an organic ligand or an inorganic ligand on their surfaces. Furthermore, these compositions may be applied to the sub-pixels of a plurality of light-emitting elements collectively by an inkjet method, a spin coating method, a dip coating method, or the like, or may be applied separately to form a pattern by discharging droplets of the composition inside the bank 23 for each sub-pixel by an inkjet method, or the like.

[0061] After the electron transport layer 24E is formed, the second electrode 25 may be formed.

[0062] 6 , the light-emitting element 5 includes light-emitting elements 5R, 5G, and 5B in a light-emitting region HR in a recess defined by the bank 23, and each of the light-emitting elements 5R, 5G, and 5B includes a first electrode 22, a hole transport layer 24H, one of light-emitting layers 24R1, 24G1, and 24B1, an electron transport layer 24E, and a second electrode 25. In the light-emitting element 5, a non-light-emitting region NHR is formed at the top of the bank 23, surrounding the light-emitting region HR.

[0063] 7, the light-emitting element 5 has luminescent layers 24R1, 24G1, and 24B1 each having a matrix formed in the luminescent region HR (which is also the pixel center), and quantum dot layers 24Rqp, 24Gqp, and 24Bqp formed in the non-luminescent region NHR (which is also the pixel peripheral edge). That is, the quantum dot layers 24Rqp, 24Gqp, and 24Bqp containing remaining organic ligands and precursors are formed so as to surround the luminescent layers 24R1, 24G1, and 24B1.

[0064] The quantum dot layers 24Rqp, 24Gqp, and 24Bqp contain residual organic ligands and precursors that do not contribute to the formation of the matrix. In contrast, the light-emitting layers 24R1, 24G1, and 24B1 are formed such that a matrix is ​​formed by applying energy, and at this time, the light-emitting layers 24R1, 24G1, and 24B1 are formed so that the volume shrinks. Therefore, the quantum dots (QDs) are denser in the light-emitting layers 24R1, 24G1, and 24B1 than in the quantum dot layers 24Rqp, 24Gqp, and 24Bqp. That is, the area density of the quantum dots (QDs) in the layer cross section of the light-emitting layers 24R1, 24G1, and 24B1 is higher than the area density of the quantum dots (QDs) contained in the quantum dot layers 24Rqp, 24Gqp, and 24Bqp. This allows the light-emitting element 5 to have higher electrical conductivity in the light-emitting region HR than in the non-light-emitting region NHR. This makes it possible to prevent leakage current from flowing through the non-light-emitting region NHR in the light-emitting element 5, and to prevent the light-emitting efficiency of the light-emitting element 5 from decreasing.

[0065] In the light-emitting element 5, by not applying energy to a portion of the quantum dot layer that forms the light-emitting layer, a difference is created between the current density of the light-emitting layer and the current density of the quantum dot layer, thereby preventing leakage current from flowing. The area density of the quantum dots (QDs) contained in the light-emitting layer is greater than the area density of the quantum dots (QDs) contained in the quantum dot layer, as can be confirmed from the difference between the current densities of the light-emitting layer and the quantum dot layer. In the examples described below, it is shown that the current density in the light-emitting layer was approximately 1.5 to 10 times higher than the current density in the non-light-emitting region (NHR) within an applied voltage range of 0.2 to 7.0 V in an electron injection evaluation (EOD evaluation). In the light-emitting element according to one embodiment, the current density of the light-emitting region HR including the light-emitting layer may be 1.5 to 10 times, and preferably 1.5 to 5 times, the current density of the non-light-emitting region NHR including the quantum dot layer within an applied voltage range of 0.2 to 7.0 V. Here, the current density of the light-emitting region HR including the light-emitting layer is 1.0×10 －６ ~10mA / cm ２ It is preferable that the －７ ~25mA / cm２ It is more preferable that:

[0066] Furthermore, since there is a difference in the area density of the quantum dots in the light-emitting layer and the quantum dot layer, it is clear that there is also a difference in the volume density of the quantum dots in the light-emitting layer and the quantum dot layer. That is, in the light-emitting device according to an embodiment of the present disclosure, the difference in the area density and volume density of the quantum dots in the light-emitting layer and the quantum dot layer can be regarded as a difference in current density in the light-emitting layer and the quantum dot layer.

[0067] Furthermore, the difference in area density and volume density of the quantum dots contained in the light-emitting layer and the quantum dot layer, which can be confirmed by current density, can be confirmed by, for example, observing the cross sections of the light-emitting layer and the quantum dot layer using a scanning electron microscope (SEM).

[0068] [Method of Manufacturing Light-Emitting Device (Embodiment 2)] The method of manufacturing a light-emitting device according to an embodiment of the present disclosure is not limited to the above-described embodiment 1. As shown in Fig. 8 , for example, a method of manufacturing a light-emitting device 5 according to an embodiment (Embodiment 2) may involve pre-mixing the quantum dot dispersion liquid and a precursor solution, followed by coating the mixture to form quantum dot layers 24Rqp, 24Gqp, and 24Bqp on the thin-film transistor layer 4, in which the organic ligands of the quantum dots (QDs) have been exchanged with the ligands of the precursor or with the precursor itself.

[0069] The types of quantum dots (QDs), organic ligands, and precursors are the same as those in embodiment 1, and therefore a description thereof will be omitted. After premixing a solution of precursors with a quantum dot dispersion, the quantum dot dispersion containing the precursors can be applied by, for example, a spin coating method or an inkjet method to form a quantum dot layer. By applying different coatings to each subpixel, quantum dot layers containing different quantum dots (QDs) can be formed. Applying different coatings to each subpixel can be performed, for example, by patterning using an inkjet method or photolithography.

[0070] As in the first embodiment, energy may be applied to the quantum dot layers 24Rqp, 24Gqp, and 24Bqp by heat treatment or exposure (light irradiation), preferably exposure (light irradiation).

[0071] In the manufacturing method of the light-emitting element according to the second embodiment, the light-emitting layers 24R1, 24G1, and 24B1 having a matrix are formed in the light-emitting region HR, and the quantum dot layers 24Rqp, 24Gqp, and 24Bqp are formed in the non-light-emitting region NHR. That is, similar to the light-emitting element 5, a light-emitting element can be manufactured in which the area density and volume density of the quantum dots (QDs) contained in the quantum dot layers 24Rqp, 24Gqp, and 24Bqp in the non-light-emitting region NHR are lower than the area density and volume density of the quantum dots (QDs) contained in the light-emitting layers 24R1, 24G1, and 24B1 in the light-emitting region HR. This prevents leakage current from flowing through the non-light-emitting region NHR, resulting in a light-emitting element that can prevent a decrease in luminous efficiency.

[0072] Also, in the method for manufacturing a light-emitting element according to the second embodiment, a light-emitting element similar to the light-emitting element 5 according to the first embodiment shown in FIG. 6 can be manufactured.

[0073] [Method of Manufacturing Light-Emitting Device (Embodiment 3)] The method of manufacturing a light-emitting device according to an embodiment of the present disclosure is not limited to the above-described Embodiment 1 and Embodiment 2. As shown in Fig. 9 , for example, a method of manufacturing a light-emitting device 5a according to an embodiment (Embodiment 3) includes forming the light-emitting layers 24R1, 24G1, and 24B1 in the above-described Embodiments 1 and 2, and then supplying a halogen ion solution 24a to the light-emitting layers 24R1, 24G1, and 24B1 to form light-emitting layers 24R2, 24G2, and 24B2 in which halogen ions are coordinated with quantum dots (QDs) (a step of impregnating the light-emitting layers with halogen ions).

[0074] The halogen ions contained in the halogen ion solution 24a for forming the light-emitting layers 24R2, 24G2, and 24B2 are typically chloride ions, and the chloride ions may be supplied from a metal halide or the like. The halogen ions may also be fluorine ions, bromine ions, or iodine ions. The halogen ions may be diluted in the precursor solvent described above and supplied to the light-emitting layers 24R1, 24G1, and 24B1.

[0075] By supplying a halogen ion solution 24a containing an excess amount of halogen ions relative to the quantum dots (QDs) to the light-emitting layers 24R1, 24G1, and 24B1, the light-emitting layers 24R2, 24G2, and 24B2 are formed, in which halogen ligands are coordinated to defects on the quantum dot (QD) surfaces. 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 positions. When the light-emitting layers 24R2, 24G2, and 24B2 are formed, halogen ions may also be contained in the quantum dot layers 24Rqp2, 24Gqp2, and 24Bqp2 in the non-light-emitting region NHR.

[0076] 10, the light-emitting element 5a has halogen ions as ligands coordinated to defects on the surface of quantum dots (QDs) and defects in the inorganic matrix in the light-emitting layers 24R2, 24G2, and 24B2, thereby enhancing the electrical conductivity of the light-emitting layers 24R2, 24G2, and 24B2.

[0077] In the light-emitting element 5a, like the light-emitting element 5, the volume density of quantum dots (QDs) contained in the light-emitting layers 24R2, 24G2, and 24B2 in the light-emitting region HR is greater than the volume density of quantum dots (QDs) contained in the quantum dot layers 24Rqp2, 24Gqp2, and 24Bqp2 in the non-light-emitting region NHR. This prevents leakage current from flowing through the non-light-emitting region NHR, and prevents a decrease in light-emitting efficiency.

[0078] More specifically, in the light-emitting element 5a, halogen ions are coordinated both in the light-emitting layers 24R2, 24G2, and 24B2 in the light-emitting region HR and in defects in the quantum dot (QD) matrix. Meanwhile, in the quantum dot layers 24Rqp2, 24Gqp2, and 24Bqp2 in the non-light-emitting region NHR, halogen ions are coordinated only in defects in the quantum dot (QD). Therefore, in the light-emitting element 5a, more halogen ions can be coordinated in the light-emitting layers 24R2, 24G2, and 24B2 in the light-emitting region HR than in the quantum dot layers 24Rqp2, 24Gqp2, and 24Bqp2 in the non-light-emitting region NHR, thereby increasing the density of halogen ions. Therefore, the electrical conductivity of the light-emitting layers 24R2, 24G2, and 24B2 in the light-emitting region HR is also enhanced by the high density of halogen ions. That is, in the light-emitting element 5a, (i) the volume density of the quantum dots (QDs) contained in the light-emitting layers 24R2, 24G2, and 24B2 in the light-emitting region HR is greater than the volume density of the quantum dots (QDs) contained in the quantum dot layers 24Rqp2, 24Gqp2, and 24Bqp2 in the non-light-emitting region NHR, and (ii) the density of halogen ions in the light-emitting layers 24R2, 24G2, and 24B2 in the light-emitting region HR can be made higher than that in the quantum dot layers 24Rqp2, 24Gqp2, and 24Bqp2 in the non-light-emitting region NHR, thereby further preventing leakage current from flowing through the non-light-emitting region NHR.

[0079] [Method of Manufacturing Light-Emitting Device (Embodiment 4)] A method of manufacturing a light-emitting device 5b according to embodiment 4 will be described with reference to FIGS. 11 to 13 . As shown in FIG. 11 , the method of manufacturing the light-emitting device 5b uses a lift-off method to form quantum dot layers 24Rq, 24Gq, and 24Bq. The quantum dot layers 24Rq, 24Gq, and 24Bq are individually formed by repeatedly patterning the photoresist layer 60 on the hole transport layer 24H using a photomask (not shown) according to the quantum dot layers 24Rq, 24Gq, and 24Bq. In the method of manufacturing the light-emitting device 5b, the quantum dot layers 24Rq, 24Gq, and 24Bq are formed before and after the step of forming the photoresist layer 60 and the step of stripping the photoresist layer 60. The quantum dot layers 24Rq, 24Gq, and 24Bq formed on the photoresist layer 60 are removed when the photoresist layer 60 is stripped.

[0080] The quantum dot dispersion liquid and precursor solution 24p for forming the quantum dot layers 24Rq, 24Gq, and 24Bq can be the same as those in the first embodiment, and therefore a description thereof will be omitted.

[0081] The resist composition for forming the photoresist layer 60 may be a positive resist composition or a negative resist composition, but is preferably a positive resist composition. The resist composition may be applied to the sub-pixels collectively by dip coating, slit coating, spin coating, or the like, thereby providing the photoresist layer 60. The resist composition is not limited to being applied to the sub-pixels collectively, and may also be applied separately to each sub-pixel by, for example, an inkjet method or the like.

[0082] After the photoresist layer 60 is dried by heating, the photoresist layer 60 formed on the hole transport layer 24H may be exposed to light using a photomask (not shown) having a desired pattern. The light used to expose the photoresist layer 60 may be designed depending on the type of resist composition.

[0083] When the photoresist layer 60 is formed using a positive resist composition, an aqueous developer containing an alkali such as potassium hydroxide (KOH) or tetramethylammonium hydroxide (TMAH) is used as the developer. A polar organic solvent such as PEGMEA is preferably used as the stripping solvent.

[0084] Next, as shown in Figure 12, in the manufacturing method of the light-emitting element 5b, quantum dot layers 24Rq, 24Gq, and 24Bq are formed so that the peripheral edges of each of the quantum dot layers 24Rq, 24Gq, and 24Bq overlap the peripheral edges of the adjacent quantum dot layers.

[0085] The quantum dot layers 24Rq, 24Gq, and 24Bq may be immersed in a precursor solution 24p to form quantum dot layers 24Rqp, 24Gqp, and 24Bqp containing the precursor.

[0086] 13, the light-emitting element 5b has, like the light-emitting element 5, a higher area density and volume density of quantum dots (QDs) contained in the light-emitting layers 24R1, 24G1, and 24B1 in which a matrix is ​​formed than the area density and volume density of quantum dots (QDs) contained in the quantum dot layers 24Rqp, 24Gqp, and 24Bqp. Therefore, in the light-emitting element 5b, the electrical conductivity in the light-emitting region HR is higher than the electrical conductivity in the non-light-emitting region NHR, which prevents leakage current from flowing through the non-light-emitting region NHR and prevents a decrease in the luminous efficiency of the light-emitting element 5.

[0087] Furthermore, in the light-emitting element 5b, the peripheral edges of the quantum dot layers 24Rqp, 24Gqp, and 24Bqp overlap the peripheral edges of the adjacent quantum dot layers in the non-emissive region NHR, so that the thickness t2 of the overlapping quantum dot layers 24Rqp, 24Gqp, and 24Bqp on the bank 23 is greater than the thickness t1 of the emissive layers 24R1, 24G1, and 24B1. This allows the electrical conductivity of the quantum dot layers 24Rqp, 24Gqp, and 24Bqp located in the non-emissive region NHR to be lower than the electrical conductivity of the emissive layers 24R1, 24G1, and 24B1 located in the emissive region HR. This prevents leakage current from flowing through the non-emissive region NHR. Note that the thickness t1 of the emissive layers 24R1, 24G1, and 24B1 shown in FIG. 13 only needs to be smaller than the thickness t2, and they can be designed independently. For example, t1 can be designed independently and individually within a range of 5 to 100 nm for each of light-emitting layer 24R1, light-emitting layer 24G1, and light-emitting layer 24B1. Furthermore, thickness t2 of quantum dot layer 24Rqp and quantum dot layer 24Gqp, thickness t2 of quantum dot layer 24Gqp and quantum dot layer 24Bqp, and thickness t2 of quantum dot layer 24Bqp and quantum dot layer 24Rqp, which overlap each other, can be designed independently and individually within a range of 15 to 300 nm.

[0088] <Method for manufacturing light-emitting element according to modified example> As described above, the method for manufacturing a light-emitting element according to an embodiment of the present disclosure is not limited to the above-described embodiments 1 to 4. For example, in a method for manufacturing a light-emitting element according to a modified example, a plurality of light-emitting layers may be formed individually on a plurality of first electrodes by repeatedly performing the step of forming the quantum dot layer containing the precursor and the step of forming a light-emitting layer by energy application, and the quantum dot dispersions for forming the plurality of light-emitting layers may each contain a different type of quantum dot.

[0089] Furthermore, for example, a method for manufacturing a light-emitting element according to one modified example may form light-emitting layers individually on a plurality of first electrodes by repeatedly performing a step of forming a quantum dot layer and a step of forming a light-emitting layer by applying energy, and in each of the steps of forming the quantum dot layer, a quantum dot layer may be formed by applying a quantum dot dispersion liquid onto the first electrode, and a quantum dot layer containing the precursor may be formed by applying a solution of the precursor onto the quantum dot layer.

[0090] <Display Device Manufacturing Method (Embodiment 5)> A display device according to an embodiment of the present disclosure includes the light-emitting element manufacturing methods according to the above-described Embodiments 1 to 4 and the light-emitting element manufacturing methods according to the above-described modified examples. Therefore, the scope of the present disclosure also includes display device manufacturing methods that include the light-emitting element manufacturing methods according to the above-described Embodiments 1 to 4 and the modified examples.

[0091] [Display Device 1] FIG. 14 is a plan view showing a schematic configuration of a display device 1 according to an embodiment.

[0092] 14 , the display device 1 includes a frame region NDA and a display region DA. The display region DA of the display device 1 includes a plurality of pixels PIX, each of which includes a red subpixel RSP, a green subpixel GSP, and a blue subpixel BSP. In this embodiment, a case where one pixel PIX is configured with a red subpixel RSP, a green subpixel GSP, and a blue subpixel BSP will be described as an example, but this is not limiting. For example, one pixel PIX may include subpixels of other colors in addition to the red subpixel RSP, the green subpixel GSP, and the blue subpixel BSP.

[0093] FIG. 15 is a cross-sectional view showing a schematic configuration of the display area DA of the display device 1.

[0094] As shown in Figure 15, 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 a substrate 12 in this order from the substrate 12 side.

[0095] 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 a first electrode 22, a functional layer 24R including a red light-emitting layer 24R1, and a second electrode 25. The green light-emitting element 5G included in the green subpixel GSP includes a first electrode 22, a functional layer 24G including a green light-emitting layer 24G1, and a second electrode 25. The blue light-emitting element 5B included in the blue subpixel BSP includes a first electrode 22, a functional layer 24B including a blue light-emitting layer 24B1, and a second electrode 25. In addition, in Figure 15, in order to show the general configuration of the display area DA of the display device 1, a functional layer 24R including a red light-emitting layer, a functional layer 24G including a green light-emitting layer, and a functional layer 24B including a blue light-emitting layer are schematically illustrated as being provided for each sub-pixel of each color, and the hole transport layer 24H and the electron transport layer 24E of the functional layer 24R are not illustrated as being provided as a common layer (one layer) for each of the red sub-pixel RSP, green sub-pixel GSP, and blue sub-pixel BSP. However, in reality, like the functional layer 24R including the red light-emitting layer 24R1 provided in the red light-emitting element 5R shown in Figure 15, each of the hole transport layer 24H and the electron transport layer 24E, excluding the red light-emitting layer 24R1, are formed over the entire surface of the display area DA and are provided as a common layer for the sub-pixels of each color, similar to the second electrode 25.

[0096] The substrate 12 may be, for example, a resin substrate made of a resin material such as polyimide, or a glass substrate. In this embodiment, since the display device 1 is a flexible display device, a case where a resin substrate made of a resin material such as polyimide is used as the substrate 12 will be described as an example, but this is not limiting. If the display device 1 is a non-flexible display device, a glass substrate can be used as the substrate 12.

[0097] The barrier layer 3 is a layer that prevents foreign substances such as water and oxygen from penetrating into the transistor TR, the red light-emitting element 5R, the green light-emitting element 5G, and the blue light-emitting element 5B, and can be composed of, for example, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a laminated film of these, formed by the CVD method.

[0098] The transistor TR portion of the thin film transistor layer 4 including the transistor TR includes the 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, and the portion of the thin film transistor layer 4 including the transistor TR other than the transistor TR portion includes the inorganic insulating film 16, the inorganic insulating film 18, the inorganic insulating film 20, and the planarization film 21.

[0099] The semiconductor films SEM, SEM', and SEM'' may be made of, for example, low-temperature polysilicon (LTPS) or an oxide semiconductor (for example, an In-Ga-Zn-O based semiconductor). In this embodiment, the case where the transistor TR has a top-gate structure will be described as an example, but the present invention is not limited to this, and the transistor TR may also have a bottom-gate structure.

[0100] The gate electrode G and the source electrode S and drain electrode D can be formed of a single layer or a multilayer film of a metal containing at least one of aluminum, tungsten, molybdenum, tantalum, chromium, titanium, and copper, for example.

[0101] The inorganic insulating films 16, 18 and 20 can be formed of, for example, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a laminated film of these films, which are formed by the CVD method.

[0102] The planarizing film 21 can be made of a coatable organic material such as polyimide or acrylic.

[0103] The red light-emitting element 5R includes a first electrode 22 above the planarization film 21, a functional layer 24R including a red light-emitting layer 24R1, and a second electrode 25. The green light-emitting element 5G includes a first electrode 22 above the planarization film 21, a functional layer 24G including a green light-emitting layer 24G1, and a second electrode 25. The blue light-emitting element 5B includes a first electrode 22 above the planarization film 21, a functional layer 24B including a blue light-emitting layer 24B1, and a second electrode 25. The insulating bank 23 covering the edge of the first electrode 22 can be formed by applying an organic material such as polyimide or acrylic and then patterning it using photolithography. While one embodiment will be described with reference to an example in which the bank 23 is provided, the bank 23 need not be provided.

[0104] The sealing layer 6 is a light-transmitting film, and can be composed of, for example, an inorganic sealing film 26 that covers the second electrode 25, an organic film 27 that is above the inorganic sealing film 26, and an inorganic sealing film 28 that is above the organic film 27. The sealing layer 6 prevents foreign substances such as water and oxygen from penetrating into the red light-emitting element 5R, the green light-emitting element 5G, and the blue light-emitting element 5B.

[0105] The inorganic sealing films 26 and 28 are each an inorganic film, and may be formed, for example, by a CVD method using a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a laminated film thereof. The organic film 27 is a light-transmitting organic film with a planarizing effect, and may be formed, for example, using a coatable organic material such as acrylic. The organic film 27 may also be formed, for example, by an inkjet method. In this embodiment, the sealing layer 6 is formed of two inorganic films and one organic film disposed between the two inorganic films. However, the stacking order of the two inorganic films and one organic film is not limited to this. Furthermore, the sealing layer 6 may be formed solely of an inorganic film, solely of an organic film, one inorganic film and two organic films, or two or more inorganic films and two or more organic films.

[0106] The functional film 39 is a film having at least one of an optical compensation function, a touch sensor function, and a protection function, for example.

[0107] An embodiment of the present disclosure is described below.

[0108] As an example, a light-emitting device was manufactured that included a light-emitting layer in which the quantum dot layer was irradiated with ultraviolet light, and a quantum dot layer that was not irradiated with ultraviolet light, and the current density in each of the light-emitting layer (light-emitting region HR) and the quantum dot layer (non-light-emitting region) was evaluated.

[0109] [1] Fabrication of Light-Emitting Element A light-emitting element having an anode, a cathode, a light-emitting layer, and a quantum dot layer between them was formed according to the following procedure.

[0110] [1-1] Formation of Anode and Bank An ITO anode was formed on the upper surface of a 2.5 cm×2.5 cm glass substrate.

[0111] [1-2] Formation of Hole Transport Layer First, a dispersion of hole transport material was prepared using TFB (poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl))diphenylamine)]) as the hole transport material and chlorobenzene as the dispersion medium. Next, the dispersion was spin-coated onto the substrate on which the anode and bank had been formed, and dried by heating at 150°C for 30 minutes, thereby forming a hole transport layer on the anode of the glass substrate.

[0112] [1-3] Formation of Quantum Dot Layer An octane dispersion of quantum dots CdSe / ZnSe / ZnS was prepared so that the quantum dot concentration was 20 mg / ml. Next, the quantum dot octane dispersion was applied by spin coating onto a hole transport layer formed on a glass substrate to form a quantum dot layer.

[0113] Next, an ethanol solution in which zinc isopropyl xanthogenate was dissolved at 60 mmol / L was prepared as a precursor.

[0114] Next, the glass substrate on which the quantum dot layer was formed was immersed in the zinc isopropyl xanthogenate prepared as a precursor solution for 2 minutes at 25°C, thereby exchanging the ligands of the zinc isopropyl xanthogenate with the organic ligands of the quantum dots. The thickness of the quantum dot layer after ligand exchange was 50 nm. Note that although an example using zinc isopropyl xanthogenate as the precursor was described here, zinc methyl xanthogenate or zinc ethyl xanthogenate may be used instead of zinc isopropyl xanthogenate.

[0115] [1-4] Formation of Light-Emitting Layer (Energy Application) Subsequently, a portion (2.5 cm × 2.5 cm) of the quantum dot layer in which the ligands had been exchanged was exposed to light to form a light-emitting layer whose periphery was surrounded by the quantum dot layer. To expose a portion (1.25 cm × 2.5 cm) of the quantum dot layer, UV light with a wavelength of approximately 300 nm was used, and the exposure dose was 180 mJ / cm. ２ The thickness of the light-emitting layer after exposure was 20 nm. Since the thickness of the quantum dot layer before ultraviolet irradiation was 50 nm and the thickness of the light-emitting layer after exposure was 20 nm, the volume density and area density of the quantum dots contained in the light-emitting layer were greater than the volume density and area density of the quantum dots contained in the quantum dot layer.

[0116] [1-5] Formation of Electron Transport Layer First, a dispersion of ZnMgO was prepared as the electron transport material using ethanol as the dispersion medium. Next, the dispersion was spin-coated onto the light-emitting layer and quantum dot layer formed on the substrate, and then heated and dried at 100°C for 3 minutes to form a 60 nm-thick positive electron transport layer.

[0117] [1-6] Formation of Cathode Silver (Ag) was vapor-deposited as a cathode on the substrate on which the electron transport layer had been formed.

[0118] [Electron Injection Property Evaluation] To evaluate electron injection property (EOD), the current density in the light-emitting device was evaluated. The current density evaluation was performed using an EL optical property evaluation device (manufactured by Otsuka Electronics Co., Ltd.). As shown in Fig. 16, the current density in the light-emitting region HR was higher than the current density in the non-light-emitting region NHR at least within the applied voltage range of 0.2 to 7.0 V.

[0119] Furthermore, the difference between the current density in the light-emitting layer (light-emitting region HR) and the current density in the quantum dot layer (non-light-emitting region NHR), which can be confirmed by electron injection characteristic evaluation (EOD), can also be interpreted as the difference in the area density of the quantum dots in the light-emitting layer and the quantum dot layer, respectively. In the light-emitting device manufactured in this example, the area density of the quantum dots predicted from the current density is smaller in the quantum dot layer (non-light-emitting region NHR) than in the light-emitting layer (light-emitting region HR), and it can be said that this enables the leakage current in the non-light-emitting region NHR to be reduced.

[0120] The present disclosure is not limited to the above-described embodiments, 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 the present disclosure. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

[0121] The present disclosure can be used in a light-emitting device, a display device, and a method for forming a functional layer.

[0122] 1 Display device 4 Thin film transistor layer 5, 5a, 5b Light emitting element (plurality of light emitting elements) 5R, 5R1 Red light emitting element (light emitting element) 5G, 5G1 Green light emitting element (light emitting element) 5B, 5B1 Blue light emitting element (light emitting element) 22 First electrode 23 Bank 24R Functional layer including red light emitting layer 24G Functional layer including green light emitting layer 24B Functional layer including blue light emitting layer 24Rq Quantum dot layer (forming green light emitting layer) 24Gq Quantum dot layer (forming green light emitting layer) 24Bq Quantum dot layer (forming blue light emitting layer) 24Rqp Quantum dot layer including precursor (forming green light emitting layer) 24Gq Quantum dot layer including precursor (forming green light emitting layer) 24Bq Quantum dot layer including precursor (forming blue light emitting layer) 24R1 Red light emitting layer 24G1 Green light emitting layer (light emitting layer) 24B1 Blue light emitting layer (light emitting layer) 24R2 Red light-emitting layer (light-emitting layer) 24G2 Green light-emitting layer (light-emitting layer) 24B2 Blue light-emitting layer (light-emitting layer) 24H Hole transport layer 24E Electron transport layer 25 Second electrode 26, 28 Inorganic sealing film 27 Organic film 39 Functional film 60 Resist layer PIX Pixel RSP Red sub-pixel GSP Green sub-pixel BSP Blue sub-pixel DA Display area NDA Frame area HR Light-emitting area NHR Non-light-emitting area

Claims

1. A method for manufacturing a light-emitting device including a light-emitting layer between a first electrode and a second electrode, the light-emitting layer including quantum dots and a matrix, the method comprising the steps of: applying a quantum dot dispersion containing quantum dots and an organic ligand onto the first electrode to form a quantum dot layer; and immersing the quantum dot layer in a solution containing a precursor of the matrix to form a quantum dot layer containing the precursor; applying energy to at least a portion of the quantum dot layer containing the precursor to form a light-emitting layer containing the quantum dots and the matrix; and forming the second electrode on the light-emitting layer.

2. The method for manufacturing a light-emitting element according to claim 1, wherein in the step of forming the light-emitting layer, the energy is irradiated toward the first electrode, thereby forming the light-emitting layer from a quantum dot layer containing the precursor, while leaving a quantum dot layer containing the precursor on the outer periphery of the light-emitting layer.

3. A method for manufacturing a light-emitting device including a light-emitting layer between a first electrode and a second electrode, the light-emitting layer including quantum dots and a matrix, the method comprising: forming a quantum dot layer by applying a quantum dot dispersion liquid containing quantum dots, an organic ligand, and a precursor of the matrix onto the first electrode; forming the light-emitting layer from the quantum dot layer on the first electrode by irradiating energy toward the quantum dot layer on the first electrode; and forming the second electrode on the light-emitting layer, wherein the quantum dot layer remains on the outer periphery of the light-emitting layer.

4. A method for producing a light-emitting element according to any one of claims 1 to 3, wherein the precursor contains a metal complex having a ligand selected from xanthogenic acid, thiocarboxylic acid, and thiourea, or the precursor contains a silicon compound having at least one alkoxysilyl group.

5. The method for producing a light-emitting element according to claim 4, wherein the ligand of the metal complex or the alkoxysilyl group has an alkyl group having 1 to 5 carbon atoms.

6. The method for manufacturing a light-emitting element according to claim 4 or 5, wherein the metal complex contains zinc methylxanthogenate, zinc ethylxanthogenate, or zinc isopropylxanthogenate.

7. The method for producing a light-emitting element according to claim 4 or 5, wherein the silicon compound is selected from tetramethyl orthosilicate, tetraethyl orthosilicate, trimethoxyphenylsilane, diphenylsilanediol, 3-mercaptopropyltrimethoxysilane, and 3-mercaptopropyltriethoxysilane.

8. The method for manufacturing a light-emitting device according to any one of claims 1 to 7, wherein halogen ions are coordinated to the quantum dots contained in the quantum dot dispersion liquid.

9. The method for manufacturing a light-emitting element according to any one of claims 1, 2, and 4 to 8, wherein the precursor solution has proton-donating properties as a solvent.

10. The method for manufacturing a light-emitting element according to any one of claims 1 to 9, further comprising, after the step of forming the light-emitting layer, a step of impregnating the light-emitting layer with halogen ions.

11. A method for manufacturing a light-emitting element according to any one of claims 1 to 10, comprising the steps of: forming a resist layer on the substrate on which the first electrode is provided, before the step of forming the quantum dot layer; exposing the resist layer to light to form a pattern having openings on the first electrode; and peeling off the resist layer after the step of forming the light-emitting layer.

12. The method for manufacturing a light-emitting element according to claim 11, further comprising the step of forming a bank surrounding the first electrode before the step of forming the resist layer.

13. A method for manufacturing a light-emitting element according to claim 11 or 12, comprising either or both of the following steps: forming at least one of a hole injection layer and a hole transport layer on the first electrode before the step of forming the resist layer; and forming an electron transport layer on the light-emitting layer after the step of peeling off the resist layer and before the step of forming the second electrode.

14. A method for manufacturing a light-emitting element according to claim 11 or 12, comprising either or both of the following steps: forming an electron transport layer on the first electrode before the step of forming the resist layer; and forming at least one layer selected from a hole injection layer and a hole transport layer on the light-emitting layer after the step of peeling off the resist layer and before the step of forming the second electrode.

15. A method for manufacturing a display device having a plurality of light-emitting elements, the method comprising the steps of carrying out the method for manufacturing a light-emitting element according to any one of claims 1, 2, and 4 to 14, wherein in the step of forming the quantum dot layer, a plurality of quantum dot layers are formed by individually applying a plurality of quantum dot dispersion liquids onto a plurality of first electrodes, and the plurality of quantum dot layers are immersed in a solution of the precursor, thereby impregnating each of the plurality of quantum dot layers with the precursor, and in the step of forming the light-emitting layer, the energy is irradiated toward each of the plurality of first electrodes, thereby forming a plurality of light-emitting layers from the plurality of quantum dot layers, while leaving the quantum dot layer containing the precursor on the outer periphery of each of the light-emitting layers, and each of the plurality of quantum dot dispersion liquids contains quantum dots of different types from each other.

16. A method for manufacturing a display device having a plurality of light-emitting elements, comprising the steps of carrying out the method for manufacturing light-emitting elements according to any one of claims 1, 2, and 4 to 14, wherein the step of forming the quantum dot layer containing the precursor and the step of forming the light-emitting layer are repeatedly carried out to form light-emitting layers individually on a plurality of first electrodes, wherein in each of the quantum dot layer forming steps, the quantum dot layer is formed by applying a quantum dot dispersion liquid containing quantum dots onto the first electrode, and the quantum dot layer is formed by immersing the quantum dot layer in a solution of the precursor, wherein in each of the light-emitting layer forming steps, energy is irradiated toward the quantum dot layer containing the precursor formed on the first electrode, thereby forming light-emitting layers on the plurality of first electrodes while leaving the quantum dot layer containing the precursor on the outer periphery of the plurality of light-emitting layers, and wherein each of the quantum dot dispersion liquids contains quantum dots of different types.

17. A method for manufacturing a display device having a plurality of light-emitting elements, comprising the step of carrying out the method for manufacturing light-emitting elements according to any one of claims 1, 2, and 4 to 14, wherein the step of forming the quantum dot layer and the step of forming the light-emitting layer are repeatedly carried out to form light-emitting layers individually on a plurality of first electrodes, wherein in each of the quantum dot layer forming steps, the quantum dot layer is formed by applying a quantum dot dispersion liquid onto the first electrode, and a quantum dot layer containing the precursor is formed by applying a solution of the precursor onto the quantum dot layer, and wherein in the light-emitting layer forming step, energy is irradiated toward the quantum dot layer on the first electrode, thereby forming light-emitting layers on the plurality of first electrodes, while leaving a quantum dot layer containing the precursor on the outer periphery of each of the plurality of light-emitting layers, and wherein each of the plurality of quantum dot dispersion liquids contains quantum dots of different types from each other.

18. A method for manufacturing a display device according to claim 16 or 17, wherein in the step of forming the quantum dot layers, the quantum dot dispersion liquid is applied so that the peripheral ends of the adjacent quantum dot layers are stacked on top of each other to form each of the quantum dot layers.

19. A light-emitting device comprising a light-emitting layer between a first electrode and a second electrode, the light-emitting layer including quantum dots and a matrix, the light-emitting device further comprising a quantum dot layer surrounding the outer periphery of the light-emitting layer formed on the first electrode, the quantum dot layer including the quantum dots and a precursor, and the area density of the quantum dots in a cross section of the light-emitting layer being greater than the area density of the quantum dots in a cross section of the quantum dot layer.

20. The light-emitting device according to claim 19, wherein the volume density of the quantum dots contained in the light-emitting layer is greater than the volume density of the quantum dots contained in the quantum dot layer.

21. The light-emitting device according to claim 19 or 20, wherein the current density in the light-emitting region including the light-emitting layer is 1.5 to 10 times the current density in the non-light-emitting region including the quantum dot layer within an applied voltage range of 0.2 to 7.0 V.

22. A light-emitting element according to any one of claims 19 to 21, wherein the precursor is a metal complex containing a ligand selected from xanthogenic acid, thiocarboxylic acid, and thiourea, or the precursor contains a silicon compound having at least one alkoxysilyl group.

23. The light-emitting device according to claim 22, wherein the ligand of the metal complex or the alkoxysilyl group has an alkyl group having 1 to 5 carbon atoms.

24. The light-emitting element according to claim 22 or 23, wherein the metal complex comprises zinc methylxanthogenate, zinc ethylxanthogenate, or zinc isopropylxanthogenate.

25. The light-emitting element according to claim 22 or 23, wherein the silicon compound is selected from tetramethyl orthosilicate, tetraethyl orthosilicate, trimethoxyphenylsilane, diphenylsilanediol, 3-mercaptopropyltrimethoxysilane, and 3-mercaptopropyltriethoxysilane.

26. The light-emitting device according to any one of claims 19 to 25, wherein halogen ions are coordinated to the quantum dots.

27. The light-emitting element according to any one of claims 19 to 26, further comprising a bank surrounding the first electrode.

28. A light-emitting element according to any one of claims 19 to 27, wherein at least one layer selected from a hole injection layer and a hole transport layer is laminated between either the first electrode and the light-emitting layer or the second electrode and the light-emitting layer, and an electron transport layer is laminated between the remaining two.

29. A display device comprising a plurality of light-emitting elements according to any one of claims 19 to 28.

30. A display device according to claim 29, wherein the peripheral ends of adjacent quantum dot layers are stacked on top of each other.

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