Light-emitting element, display device, and method for manufacturing the same

Abstract

This light-emitting element 1 comprises a first electrode (D1) and a second electrode (D2), and a light-emitting layer (5) positioned between the first electrode (D1) and the second electrode (D2). The light-emitting layer (5) includes: a first nanoparticle group (A1) that includes first nanoparticles (P1) and is spread in a layered shape; first quantum dots (Q1) that are positioned between the first electrode (D1) and the first nanoparticle group (A1); and second quantum dots (Q2) that are positioned between the second electrode (D2) and the first nanoparticle group (A1).

Description

[Technical Field]

[0001] The present invention relates to a light-emitting element, a display device, and a method for manufacturing a light-emitting element. [Background technology]

[0002] Patent Documents 1 to 3 disclose light-emitting devices having a light-emitting layer containing quantum dots. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-095685 (published April 12, 2007) [Patent Document 2] US2019 / 0280232A1 (released September 12, 2019) [Patent Document 3] WO2020 / 208810A1 (International Publication: October 15, 2020) Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for improved luminous efficiency of light-emitting devices containing quantum dots. [Means for solving the problem]

[0005] A light-emitting element according to one embodiment of the present disclosure comprises a first electrode, a second electrode, and a light-emitting layer located between the first electrode and the second electrode, the light-emitting layer including a first group of nanoparticles extending in a layered manner and including first nanoparticles, a first quantum dot located between the first electrode and the first group of nanoparticles and differing from the first nanoparticles in at least one of constituent elements, composition, and particle size, and a second quantum dot located between the second electrode and the first group of nanoparticles and differing from the first nanoparticles in at least one of constituent elements, composition, and particle size. [Effects of the Invention]

[0006] According to one aspect of the present disclosure, the luminous efficiency of a light-emitting device including quantum dots is improved. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a cross-sectional view showing a configuration example of a light-emitting element according to an embodiment of the present invention. [Figure 2] 1 is a cross-sectional view showing a configuration example of a light-emitting element according to an embodiment of the present invention. [Figure 3] 1 is a cross-sectional view showing a configuration example of a light-emitting element according to an embodiment of the present invention. [Figure 4] 1 is a cross-sectional view showing a configuration example of a light-emitting element according to an embodiment of the present invention. [Figure 5] FIG. 1 is a cross-sectional view showing an example of the configuration of a nanoparticle. [Figure 6] FIG. 1 is a cross-sectional view showing an example of the configuration around a nanoparticle. [Figure 7] FIG. 2 is a cross-sectional view showing an example of the configuration of nanoparticle groups. [Figure 8] FIG. 2 is a cross-sectional view showing an example of the configuration of a quantum dot. [Figure 9] 1 is a cross-sectional view showing a configuration example of a light-emitting element according to an embodiment of the present invention. [Figure 10] 1 is a cross-sectional view showing a configuration example of a light-emitting element according to an embodiment of the present invention. [Figure 11] 1 is a cross-sectional view showing a configuration example of a light-emitting element according to an embodiment of the present invention. [Figure 12] 1 is a cross-sectional view showing a configuration example of a light-emitting element according to an embodiment of the present invention. [Figure 13] 1 is a cross-sectional view showing a configuration example of a light-emitting element according to an embodiment of the present invention. [Figure 14] 1 is a cross-sectional view showing a configuration example of a light-emitting element according to an embodiment of the present invention. [Figure 15] 1 is a flowchart illustrating an example of a method for manufacturing a light-emitting element according to the present embodiment. [Figure 16] 1 is a flowchart illustrating an example of a method for manufacturing a light-emitting element according to the present embodiment. [Figure 17] 1 is a schematic diagram illustrating a configuration example of a display device including a light-emitting element according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] (light-emitting element) 1 is a cross-sectional view showing an example of the configuration of a light-emitting device according to the present embodiment. As shown in FIG. 1, the light-emitting device 1 according to the present embodiment includes a first electrode D1, a second electrode D2, and a light-emitting layer 5 located between the first electrode D1 and the second electrode D2. The light-emitting layer 5 includes a first nanoparticle group A1 that spreads in a layer shape and includes first nanoparticles P1; a first quantum dot Q1 located between the first electrode D1 and the first nanoparticle group A1 and differing from the first nanoparticles P1 in at least one of their constituent elements, composition, and particle size; and a second quantum dot Q2 located between the second electrode D2 and the first nanoparticle group A1 and differing from the first nanoparticles P1 in at least one of their constituent elements, composition, and particle size. The term "different compositions" means that the constituent elements are the same but the constituent ratios (composition ratios) are different.

[0009] The quantum dots of the present disclosure refer to particles capable of emitting light with a maximum width of 100 nm or less. The shape of the quantum dots, i.e., the particle shape, 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, they 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. Typically, they include semiconductors. The term "semiconductor" as used herein refers to a material capable of emitting light with a certain band gap, and includes at least the following materials: Specifically, semiconductors include, for example, at least one selected from the group consisting of II-VI compounds, III-V compounds, chalcogenides, and perovskite compounds. Note that II-VI compounds refer to compounds containing Group II and Group VI elements, and III-V compounds refer to compounds containing Group III and Group V elements. Furthermore, Group II elements may include Group 2 and Group 12 elements, Group III elements may include Group 3 and Group 13 elements, Group V elements may include Group 5 and Group 15 elements, and Group VI elements may include Group 6 and Group 16. Note that the numbering of element groups using Roman numerals is based on the old IUPAC system or the old CAS system, while the numbering of element groups using Arabic numerals is based on the current IUPAC system. The II-VI compound includes, for example, at least one selected from the group consisting of MgS, MgSe, MgTe, CaS, CaSe, CaTe, SrS, SrSe, SrTe, BaS, BaSe, BaTe, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, and HgTe. The III-V compound includes, for example, at least one selected from the group consisting of GaAs, GaP, InN, InAs, InP, and InSb. Chalcogenides are compounds containing elements from group VI A(16), such as CdS or C The chalcogenide may include a mixed crystal of these. The perovskite compound has a composition represented by the general formula CsPbX 3 , for example. The constituent element X includes at least one element selected from the group consisting of Cl, Br, and I.

[0010] Nanoparticles refer to nano-sized particles (diameter less than 1000 nm). The shape of the particles may be the same as that of quantum dots.

[0011] The first nanoparticle P1 may be transparent. The first and second quantum dots Q1 and Q2 may emit electroluminescence with an emission wavelength in the visible light range.

[0012] One of the first electrode D1 and the second electrode D2 is an anode, and the other is a cathode. When a voltage is applied between the anode and the cathode, holes from the anode recombine with electrons from the cathode in the light-emitting layer 5 containing the first and second quantum dots Q1 and Q2. The excitons generated by this recombination then return to their ground state, thereby generating light. The light generated in the light-emitting layer 5 may be blue, green, or red light.

[0013] The first nanoparticle group A1 functions as a spacer, maintaining the distance between the first and second quantum dots Q1 and Q2 in the Z direction, with the thickness direction of the light-emitting layer 5 being the Z direction. This improves the luminous efficiency of the light-emitting element 1. This is because, when the distance between quantum dots (e.g., the distance in the Z direction) is small, excitation energy is easily transferred between quantum dots, which can cause a decrease in luminous efficiency. For example, when the distance between quantum dots is small, excitation energy is known to be transferred via fluorescence resonance energy transfer (FRET). FRET can transfer excitons to other quantum dots or non-emissive centers. The latter can cause exciton deactivation, i.e., a decrease in the luminous efficiency of the quantum dots. Furthermore, for example, when the distance between quantum dots is small, the quantum dot density (number of quantum dots per volume) increases. When the quantum dot density is high, the luminescence from the quantum dots can be absorbed by other quantum dots or non-emissive centers. The latter can cause a decrease in the luminous efficiency of the quantum dots. The first nanoparticle group A1 functions as a protective layer for the first quantum dots Q1, thereby reducing damage to the first quantum dots Q1 during subsequent processes. The first and second quantum dots Q1 and Q2 may be composed of the same material, have the same particle size, and emit the same color. Here, "emission of the same color" refers to emission from quantum dots with compositions and particle sizes within a range that can be used in a light-emitting device to be considered the same color. "The same color" refers to emission from any of the primary colors that constitute a display image, such as red, green, and blue. Therefore, the same color is sufficient as long as it is nearly identical within the range visible to the human eye; strictly speaking, the peak wavelengths of the light dots do not necessarily have to be completely identical. For example, if two peaks are detected in the emission wavelength spectra of two types of quantum dots, and the respective peak wavelengths are within the respective wavelength ranges of 400 nm to 500 nm (blue), 500 nm to 600 nm (green), and 600 nm to 780 nm (red), then those quantum dots are considered to emit the same color. It is also considered to be the same when two peaks are not detected in the emission wavelength spectrum of multiple quantum dots.

[0014] "Equivalent particle size" means that, in a cross-sectional observation image of the light-emitting layer 5 in the thickness direction (Z direction), particles as close as possible are extracted, and the particle size of a total of 30 particles is measured. A histogram is created with particle size as the horizontal axis, and six classes are used from maximum to minimum data. "Different particle size" means that two or more peaks are observed in a similar histogram. When comparing particle size distributions of particles at different locations, the comparison should be performed using approximately the same number of samples from different locations. For particle sizes where the cross section is not circular, the diameter of a circle with an area equivalent to the area in the cross-sectional observation image of the particle can be used as the particle size.

[0015] The first nanoparticle P1 may include an insulating material. At least a portion (particularly the central core) or the entirety of the first nanoparticle P2 may be made of a light-transmitting insulating material such as SiO2, Al2O3, diamond, etc. The first nanoparticle P1 may be insulating (having electrical conductivity 1 / 10 or less of that of the first quantum dot Q1) or non-luminescent (having luminous efficiency 1 / 10 or less of that of the first quantum dot Q1).

[0016] The particle size of the second quantum dots Q2 may be the same as the particle size of the first quantum dots Q1, in which case the first nanoparticle group A1 can be easily formed into a layer. The particle size of the first nanoparticles P1 may be the same as the particle size of the first quantum dots Q1, in which case the first nanoparticles P1 are more likely to be located in the closest-packed position, allowing for more precise control of the arrangement of the first nanoparticle group A1. This allows for more precise control of the distance between the first quantum dots Q1 and the second quantum dots Q2.

[0017] 2 is a cross-sectional view showing an example of the configuration of the light-emitting device of this embodiment. As shown in FIG. 2, the particle size of the first nanoparticles P1 may be smaller than the particle size of the first quantum dots Q1, in which case, the spacer gap is reduced. The band gap of the first nanoparticles P1 may be larger than the band gap of the first quantum dots Q1, in which case, luminescent recombination in the first nanoparticles P1 is less likely to occur.

[0018] The band gap of the first nanoparticles P1 may be 3.1 eV or more (emission wavelength of 400 nm or less) or 1.8 eV or less (emission wavelength of 700 nm or more). In this case, the first nanoparticles P1 do not emit visible light, and color mixing (broadening of the emission wavelength characteristics of the light-emitting element ED) can be prevented.

[0019] The light-emitting layer 5 may have a layer-like first quantum dot group 10 including the first quantum dot Q1, in which case more first quantum dots Q1 can be included in the light-emitting layer 5. The light-emitting layer 5 may have a layer-like first quantum dot group 20 including the second quantum dot Q2, in which case more second quantum dots Q2 can be included in the light-emitting layer 5.

[0020] The first electrode D1 may be one of an anode and a cathode, and the second electrode D2 may be the other. A first charge functional layer F1 (e.g., one of an electron transport layer and a hole transport layer) may be provided between the first electrode D1 and the first quantum dot group 10, and a second charge functional layer F2 (e.g., the other of an electron transport layer and a hole transport layer) may be provided between the second quantum dot group 20 and the second electrode D2.

[0021] 3 is a cross-sectional view showing an example of the configuration of the light-emitting element of this embodiment. As shown in FIG. 3, the light-emitting layer 5 may include second nanoparticles P2 located between the first electrode D1 and the first nanoparticle group A1. The second nanoparticles P2 and the first quantum dots Q1 may be adjacent to each other in a direction (X direction) perpendicular to the thickness direction of the light-emitting layer 5. In this case, the distance between adjacent first quantum dots Q1 in the X direction can be maintained, improving the luminous efficiency of the light-emitting element 1. The second nanoparticles P2 may be semiconductor crystals with a larger band gap than the first quantum dots Q1. In this case, luminescent recombination in the second nanoparticles P2 is less likely to occur.

[0022] The light-emitting layer 5 may include third nanoparticles P3 located between the second electrode D2 and the first nanoparticle group A1. The third nanoparticles P3 and the second quantum dots Q2 may be adjacent to each other in a direction (X direction) perpendicular to the thickness direction of the light-emitting layer 5. This improves the luminous efficiency of the light-emitting element 1 for the same reason as the second nanoparticles. The third nanoparticles P3 may be semiconductor crystals with a larger band gap than the second quantum dots Q2. This makes it difficult for luminescent recombination to occur in the third nanoparticles P3.

[0023] 4 is a cross-sectional view showing an example of the configuration of the light-emitting device of this embodiment. As shown in FIG. 4, the particle size of the second nanoparticles P2 may be smaller than the particle size of the first quantum dots Q1, and multiple second nanoparticles P2 may be disposed in the gaps between adjacent first quantum dots Q1. Since the distance is controlled by the second nanoparticles P2 with smaller diameters, more precise control is possible. Furthermore, since the distance is controlled by the multiple second nanoparticles P2, gaps are less likely to occur.

[0024] FIG. 5 is a cross-sectional view showing an example of the structure of nanoparticles. The first nanoparticle P1, the second nanoparticle P2, the third nanoparticle P3, etc. are collectively referred to as nanoparticles P. The nanoparticles P may contain at least one of an n-type conductive material and a p-type conductive material, or may be composed of at least one of an n-type conductive material and a p-type conductive material. This can improve the carrier balance in the light-emitting layer 5 (e.g., increase the hole injection ratio). As shown in FIG. 5, at least a part or all of the outer periphery 3 of the nanoparticle P may be composed of an n-type conductive material (e.g., an n-type semiconductor) or a p-type conductive material (e.g., a p-type semiconductor). If at least a part or all of the outer periphery 3 has p-type or n-type conductivity, the conductivity of that part can be improved. The core 2 of the nanoparticle P may be made of an insulating material. The entire outer periphery 3 of the nanoparticle P1 may be composed of an n-type conductive material (the core 2 is coated with an n-type conductive material), or the entire outer periphery 3 of the nanoparticle P may be composed of a p-type conductive material (the core 2 is coated with a p-type conductive material).

[0025] Examples of n-type conductive materials include ZnO, ZnMgO, n-type chalcopyrite compounds, etc. Examples of p-type conductive materials include Ag-doped NiO and p-type chalcopyrite compounds.

[0026] 6 is a cross-sectional view showing an example of the structure around a nanoparticle. As shown in FIG. 6, the periphery PS of the nanoparticle P may contain at least one of a halogen and a chalcogen.

[0027] The first nanoparticle group A1 and the like are collectively referred to as nanoparticle group A, and nanoparticle group A may include nanoparticles P containing an n-type conductive material and other nanoparticles P containing a p-type conductive material. Fig. 7 is a cross-sectional view showing an example of the configuration of a nanoparticle group. As shown in Fig. 7, nanoparticle group A may include nanoparticles P whose cores 2 are coated with an n-type conductive material NZ and other nanoparticles P whose cores 2 are coated with a p-type conductive material PZ.

[0028] FIG. 8 is a cross-sectional view showing an example of the structure of a quantum dot. The first quantum dot Q1, the second quantum dot Q2, etc. are collectively referred to as quantum dot Q. The quantum dot Q may be a core-shell type having a core 7 and a shell 8, or a shellless type consisting of only the core 7. The quantum dot Q may be configured with multiple ligands T arranged around it. The ligand T may contain at least one of a halogen and a chalcogen. Examples of halogen include fluorine, chlorine, and bromine. When the distance between quantum dots is small, the ligands tend to peel off, causing the quantum dots to become deactivated. However, by providing nanoparticles between the quantum dots, the rate of deactivation due to ligand peeling can be reduced. The ligand T may be composed of an organic compound.

[0029] 9 and 10 are cross-sectional views showing examples of the configuration of the light-emitting element of this embodiment. As shown in Fig. 9 and 10, the light-emitting layer 5 may have a layer-like third nanoparticle group A3 containing third nanoparticles P3. In this case, as shown in Fig. 10, the third nanoparticle group A3 containing a plurality of third nanoparticles P3 may be located at the top (uppermost layer) of the light-emitting layer 5 and contact the charge functional layer F2. The first nanoparticle group A1 may be insulating and the third nanoparticle group A3 may be n-type conductive, in which case the first electrode D1 may be an anode and the second electrode D2 may be a cathode.

[0030] 11 is a cross-sectional view showing an example of the configuration of the light-emitting device of this embodiment. As shown in FIG. 11, a first quantum dot group 10 including a plurality of first quantum dots Q1 may be located at the bottom (lowest layer) of the light-emitting layer 5 and may be in contact with the charge functional layer F1.

[0031] FIG. 12 is a cross-sectional view showing an example of the configuration of the light-emitting device of this embodiment. As shown in FIG. 12, the light-emitting layer 5 may include third quantum dots Q3 located between the second electrode D2 and the third nanoparticle group A3. The configuration may include, from bottom to top, the first quantum dot group 10, the first nanoparticle group A1, the second quantum dot group 20, the third nanoparticle group A3 including a plurality of third nanoparticles P3, and the third quantum dot group 30 including a plurality of third quantum dots Q3. For example, to improve carrier balance (improve electron excess), the nanoparticle group closer to the anode (A1 if D1 is the anode, A3 if D2 is the anode) may be p-type conductive, and the nanoparticle group closer to the cathode (A3 if D2 is the cathode, A1 if D2 is the anode) may be insulating.

[0032] Fig. 13 is a cross-sectional view showing an example of the configuration of the light-emitting device of this embodiment. As shown in Fig. 13, the first nanoparticle group A1 may be spread in a layered manner, and the first nanoparticle group A1 (a layer made up of a plurality of first nanoparticles P1 adjacent to each other in the X direction) may be discontinuous within the cross section.

[0033] Fig. 14 is a cross-sectional view showing an example of the configuration of a light-emitting element of this embodiment. The light-emitting element shown in Fig. 14 includes a first electrode D1, a second electrode D2, and a light-emitting layer 5 located between the first electrode D1 and the second electrode D2. The light-emitting layer 5 includes a plurality of quantum dots Q spread in a layered manner. With respect to a cross section of the light-emitting layer 5 in the layer thickness direction (Z direction), a first line segment L1 exists that extends in a first direction (X direction) perpendicular to the Z direction and through which more than 50% of the particles passing through are quantum dots Q. This means that the plurality of quantum dots Q can be said to spread in a layered manner.

[0034] Similarly, the light-emitting layer 5 includes a plurality of quantum dots Q spread in a layered manner. The presence of a second line segment L2 that is parallel to the first line segment L1 and is closer to the second electrode D2 than the first line segment L1, and through which more than 50% of the particles passing through are quantum dots Q, means that the plurality of quantum dots Q are spread in a layered manner. Similarly, the light-emitting layer 5 includes a plurality of nanoparticles P that are spread in a layered manner. The presence of a third line segment L3 that is parallel to the first line segment L1 and is located between the first line segment L1 and the second line segment L2, and through which more than 50% of the particles passing through are nanoparticles P means that the plurality of nanoparticles P are spread in a layered manner.

[0035] The first line segment L1, the second line segment L2, and the third line segment L3 are the same length (e.g., 100 nm) and aligned in the X direction. The nanoparticles P may be said to be spread in layers if they are at least adjacent to one another in the X direction and if more than 60%, 70%, 80%, or 90% of the particles passed by L3 are nanoparticles P. Similarly, the quantum dots Q may be said to be spread in layers if they are at least adjacent to one another in the X direction and if more than 60%, 70%, 80%, or 90% of the particles passed by L1 or L2 are nanoparticles P.

[0036] (Method of manufacturing light-emitting element) 15 and 16 are flowcharts showing an example of a method for manufacturing the light-emitting device of this embodiment. As shown in Fig. 1 and Fig. 15, the method for manufacturing the light-emitting device of this embodiment includes the steps of: forming a first electrode D1 (S10); arranging first quantum dots Q1 above the first electrode D1 (S20); arranging a first nanoparticle group A1 containing first nanoparticles P1 and spreading in a layer shape above the first quantum dots Q1 (S30); arranging second quantum dots Q2 above the first nanoparticle group A1 (S40); and forming a second electrode D2 above the second quantum dots Q2 (S50).

[0037] 16, after steps S10 and S30, a step (S15) of forming a first charge functional layer F1, a step (S23) of applying a solution containing first quantum dots Q1 onto the first charge functional layer F1 (above the first electrode D1), and a step (S25) of baking the solution applied onto the first charge functional layer F1 may be performed. When manufacturing a light-emitting element ED as shown in FIGS. 3 and 4, a solution containing the first quantum dots Q1 and second nanoparticles P2 may be applied onto the first charge functional layer F1 (above the first electrode D1) in step S23.

[0038] Example 1 The light-emitting device of FIG. 1 may be formed as follows. First, a first quantum dot liquid containing first quantum dots Q1, a first nanoparticle liquid containing first nanoparticles P1, and a second quantum dot liquid containing second quantum dots Q2 are prepared. The first and second quantum dots Q1 and Q2 have the same structure. The concentration of the first quantum dots Q1 in the first quantum dot liquid is 20 mg / ml, and the solvent for the first quantum dot liquid is octane. The first nanoparticles P1 in the first nanoparticle liquid are made of SiO2, the concentration of the first nanoparticles P1 is 30 mg / ml, and the solvent for the first nanoparticle liquid is octane.

[0039] Next, the first quantum dot liquid was applied onto the first charge functional layer F1 (e.g., hole transport layer) by spin coating. The rotation speed in the spin coating was 3000 rpm / 40 sec. The average thickness of the layer of first quantum dots A1 obtained after baking the first quantum dot liquid was approximately 1 time the diameter of the first quantum dots Q1.

[0040] Next, the first nanoparticle liquid was applied onto the first quantum dot group A1 by spin coating. The rotation speed in the spin coating was 3500 rpm / 40 sec. The average thickness of the obtained first nanoparticle group 10 was approximately 1 time the diameter of the first nanoparticles P1.

[0041] Next, the second quantum dot liquid was applied onto the first nanoparticle group 10 by spin coating. The rotation speed in the spin coating was 3000 rpm / 40 sec. The average thickness of the layer of the second quantum dot group 20 obtained after baking the second quantum dot liquid was approximately 1 time the diameter of the second quantum dots Q2.

[0042] Example 2 The nanoparticles in Figure 5 may be formed as follows. SiO2 nanoparticles were prepared as the core 2 of nanoparticle P. Next, zinc acetate dihydrate (Zn(CH3COO)2·2H2O), ammonia (NH3), and sodium dodecyl sulfate (SDS) were added to a mixed solvent of water (H2O) and ethanol (EtOH) to obtain a mixed solution. Next, the SiO2 nanoparticles were added to the mixed solution and stirred while heated to 75°C. This resulted in the growth of zinc oxide (ZnO) on the SiO2. As a result, nanoparticles P were obtained, including a core 2 made of an insulating material and an outer periphery 3 (shell) made of an n-type conductive material.

[0043] Example 3 The nanoparticles of FIG. 5 may be formed as follows. SiO2 nanoparticles were prepared as the core 2 of the nanoparticle P. Nickel acetate tetrahydrate was added to the nanoparticles at a concentration of 0.1 mol / L to 0.4 mol / L. Add it to a mixed solvent of methoxyethanol and aminoethanol so that the concentration becomes 1 / L. A mixed solution was obtained. The SiO2 nanoparticles were added to the mixed solution and stirred while heating. This resulted in the growth of nickel oxide (NiO) on the SiO2. As a result, nanoparticles P were obtained, each having a core 2 made of an insulating material and an outer periphery 3 (shell) made of a p-type conductive material.

[0044] (display device) 17 is a schematic diagram showing a configuration example of a display device including the light-emitting element of this embodiment. As shown in FIG. 17, a display device 50 includes a display section 60 including a plurality of sub-pixels SB, SG, and SR, and a driver 70 that drives the plurality of sub-pixels SB, SG, and SR. For example, the sub-pixel SB includes a light-emitting element ED and a pixel circuit PC connected to the light-emitting element ED. The sub-pixel SB may be a blue sub-pixel including a blue-emitting light-emitting element ED. The sub-pixel SG may be a green sub-pixel, The sub-pixel SR may be a red sub-pixel.

[0045] (Appendix) The above-described embodiments are intended to be illustrative and explanatory, and not limiting, and many variations will be apparent to those skilled in the art based on these examples and descriptions. [Explanation of symbols]

[0046] 5. Light-emitting layer 10 First quantum dot group 20 Second quantum dot group 50 Display device A1 First nanoparticle group A3 Third nanoparticle group D1 First electrode (anode) D2 Second electrode (cathode) ED light emitting element Q1 First quantum dot Q2 Second quantum dot P1 First nanoparticle P2 Secondary nanoparticles

Claims

1. a first electrode, a second electrode, and a light-emitting layer located between the first electrode and the second electrode; the light-emitting layer includes: a first nanoparticle group that includes first nanoparticles and spreads in a layered manner; first quantum dots that are located between the first electrode and the first nanoparticle group and differ from the first nanoparticles in at least one of a constituent element, composition, and particle size; and second quantum dots that are located between the second electrode and the first nanoparticle group and differ from the first nanoparticles in at least one of a constituent element, composition, and particle size; The light-emitting device, wherein the first nanoparticles include an insulating material.

2. A light-emitting device comprising a first electrode and a second electrode, and a light-emitting layer located between the first electrode and the second electrode; the light-emitting layer includes: a first nanoparticle group that includes first nanoparticles and spreads in a layered manner; first quantum dots that are located between the first electrode and the first nanoparticle group and differ from the first nanoparticles in at least one of a constituent element, composition, and particle size; and second quantum dots that are located between the second electrode and the first nanoparticle group and differ from the first nanoparticles in at least one of a constituent element, composition, and particle size; A light-emitting device, wherein the particle size of the first nanoparticles is equal to or smaller than the particle size of the first quantum dots.

3. A light-emitting device comprising a first electrode and a second electrode, and a light-emitting layer located between the first electrode and the second electrode; the light-emitting layer includes: a first nanoparticle group that includes first nanoparticles and spreads in a layered manner; first quantum dots that are located between the first electrode and the first nanoparticle group and differ from the first nanoparticles in at least one of a constituent element, composition, and particle size; and second quantum dots that are located between the second electrode and the first nanoparticle group and differ from the first nanoparticles in at least one of a constituent element, composition, and particle size; The band gap of the first nanoparticles is larger than the band gap of the first quantum dots.

4. A light-emitting device comprising a first electrode and a second electrode, and a light-emitting layer located between the first electrode and the second electrode; the light-emitting layer includes: a first nanoparticle group that includes first nanoparticles and spreads in a layered manner; first quantum dots that are located between the first electrode and the first nanoparticle group and differ from the first nanoparticles in at least one of a constituent element, composition, and particle size; and second quantum dots that are located between the second electrode and the first nanoparticle group and differ from the first nanoparticles in at least one of a constituent element, composition, and particle size; The first nanoparticle group includes the first nanoparticles containing an n-type conductive material and other first nanoparticles containing a p-type conductive material.

5. A light-emitting device comprising a first electrode and a second electrode, and a light-emitting layer located between the first electrode and the second electrode; the light-emitting layer includes: a first nanoparticle group that includes first nanoparticles and spreads in a layered manner; first quantum dots that are located between the first electrode and the first nanoparticle group and differ from the first nanoparticles in at least one of a constituent element, composition, and particle size; and second quantum dots that are located between the second electrode and the first nanoparticle group and differ from the first nanoparticles in at least one of a constituent element, composition, and particle size; A light-emitting element, wherein the light-emitting layer includes second nanoparticles positioned between the first electrode and the first group of nanoparticles, or includes third nanoparticles positioned between the second electrode and the first group of nanoparticles.

6. The light-emitting element according to any one of claims 1 to 5, wherein the first quantum dots and the second quantum dots have at least one of the same particle size, the same constituent elements, and the same luminescent color.

7. 7. The light-emitting element according to claim 1, wherein the first nanoparticles contain at least one of an n-type conductive material and a p-type conductive material.

8. The light-emitting element according to claim 7 , wherein at least one of the n-type conductive material and the p-type conductive material is present in the first nanoparticle at a periphery of the first nanoparticle.

9. 9. The light-emitting device according to claim 1, wherein the first nanoparticles are coated with an n-type conductive material or a p-type conductive material.

10. The light-emitting element according to claim 4 , wherein the first group of nanoparticles includes the first nanoparticles coated with an n-type conductive material and other first nanoparticles coated with a p-type conductive material.

11. 11. The light-emitting device according to claim 1, wherein at least one of a halogen and a chalcogen is contained around the first nanoparticles.

12. A light-emitting element as described in claim 5, wherein the second nanoparticle and the first quantum dot are adjacent to each other in a direction perpendicular to the thickness direction of the light-emitting layer, or the third nanoparticle and the second quantum dot are adjacent to each other in a direction perpendicular to the thickness direction of the light-emitting layer.

13. An emitting element as described in claim 5 or 12, wherein the second nanoparticles are semiconductor crystals having a larger band gap than the first quantum dots, or the third nanoparticles are semiconductor crystals having a larger band gap than the second quantum dots.

14. The light-emitting device according to claim 5 , 12 or 13 , wherein the particle diameter of the second nanoparticles is smaller than the particle diameter of the first quantum dots.

15. The light-emitting element according to claim 5 , wherein the light-emitting layer has a group of third nanoparticles that includes the third nanoparticles and that are spread in a layer shape.

16. The light-emitting device according to claim 15 , wherein the third group of nanoparticles is located at the top of the light-emitting layer.

17. The light-emitting device of claim 15 , wherein the first group of nanoparticles is insulating and the third group of nanoparticles is n-type conductive.

18. The light-emitting device of claim 15 , wherein the light-emitting layer includes third quantum dots located between the second electrode and the third group of nanoparticles.

19. A display device comprising the light-emitting device according to any one of claims 1 to 18.

20. forming a first electrode; disposing a first quantum dot above the first electrode; disposing a layer-like group of first nanoparticles containing first nanoparticles above the first quantum dots; disposing second quantum dots above the first group of nanoparticles; forming a second electrode above the second quantum dots; In the step of disposing the first quantum dots, a solution containing the first quantum dots is applied to a position above the first electrode. The method for manufacturing a light-emitting element, wherein the solution contains second nanoparticles.

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