Light-emitting element, light-emitting device, display device, and production method for light-emitting element

Abstract

A light-emitting element (ED) according to the present disclosure comprises: a light-emitting layer (EML) that is positioned between an anode (AN) and a cathode (CA) and contains light-emitting quantum dots (QD) and a first ligand material (L1) capable of coordinating the quantum dots; and an adjacent layer (ADL) that is in contact with the upper surface of the light-emitting layer (EML), wherein the adjacent layer (ADL) contains a matrix material (M2) containing a crosslinkable organic substance and a second ligand material (L2) that is enveloped in the matrix material (M2).

Description

Light-emitting element, light-emitting device, display device, and method for manufacturing light-emitting element

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

[0002] Patent Document 1 discloses that after repeating a plurality of times the steps of forming a charge transport layer and a photoresist on a light-emitting layer, patterning the photoresist by exposure, and patterning both the light-emitting layer and the charge transport layer by etching, the charge transport layer is dissolved to remove unnecessary upper layers such as the photoresist, or the charge transport layer is retained and used as the charge transport layer.

[0003] Japanese Patent Laid-Open No. 2014-120218

[0004] In steps such as the step of patterning the light-emitting layer, the step of forming an upper layer above the light-emitting layer, and the step of cleaning the light-emitting layer, the ligand material is easily eluted from the light-emitting layer. Therefore, there is a demand for a configuration capable of reducing the elution amount of the ligand material from the light-emitting layer.

[0005] A light-emitting element according to an embodiment of the present disclosure includes an anode and a cathode, a light-emitting layer located between the anode and the cathode, the light-emitting layer including light-emitting quantum dots and a first ligand material capable of coordinating to the quantum dots, and an adjacent layer located between the anode and the cathode and in contact with the light-emitting layer, wherein the adjacent layer includes a base material containing a crosslinkable organic substance and a second ligand material encapsulated in the base material.

[0006] A light-emitting device according to an embodiment of the present disclosure includes a first light-emitting element which is a light-emitting element according to an embodiment of the present disclosure and includes a first light-emitting layer emitting light of a first color as the light-emitting layer, and a second light-emitting element which is a light-emitting element according to an embodiment of the present disclosure and includes a second light-emitting layer emitting light of a second color as the light-emitting layer, wherein the first color and the second color are different primary colors.

[0007] A display device according to an embodiment of the present disclosure is configured to include the light-emitting device according to an embodiment of the present disclosure.

[0008] A method for manufacturing a light-emitting element according to one embodiment of the present disclosure includes the steps of forming a light-emitting layer containing light-emitting quantum dots and a first ligand material that can coordinate to the quantum dots, and forming an adjacent layer that is in contact with the light-emitting layer and contains a matrix material containing a crosslinkable organic material and a second ligand material encapsulated in the matrix material.

[0009] According to one embodiment of the present disclosure, the adjacent layer can reduce the amount of ligand material eluted from the light-emitting layer, and / or the adjacent layer can replenish the ligand material to the light-emitting layer.

[0010] This is a cross-sectional view showing an example of the configuration of a light-emitting element according to one embodiment of the present disclosure. This is a cross-sectional view showing another example of the configuration of a light-emitting element according to one embodiment of the present disclosure. This is a band diagram showing an example of the band structure of the light-emitting element shown in Figure 1. This is a band diagram showing an example of the band structure of the light-emitting element shown in Figure 2. This is a schematic diagram showing an example of the concentration distribution of ligand material in the light-emitting layer and adjacent layer shown in Figures 1 and 2. This is a schematic diagram showing another example of the concentration distribution of ligand material in the light-emitting layer and adjacent layer shown in Figures 1 and 2. This is a cross-sectional view showing an example of the configuration of a light-emitting device equipped with the light-emitting element shown in Figure 1. This is a cross-sectional view showing another an example of the manufacturing method of the light-emitting element shown in Figures 1 and 2. This is a cross-sectional view showing an example of the configuration of a light-emitting element ED according to one embodiment of the present disclosure. This is a cross-sectional view showing an example of the configuration of a light-emitting element ED according to one embodiment of the present disclosure. This is a cross-sectional view showing yet another example of the configuration of a light-emitting element ED according to one embodiment of the present disclosure. This is a cross-sectional view showing an example of the configuration of a light-emitting device equipped with the light-emitting element shown in Figures 12 and 13. This is a cross-sectional view showing another example of the configuration of a light-emitting device equipped with the light-emitting element shown in Figures 12 and 13. This is a cross-sectional view showing another example of the configuration of a light-emitting device equipped with the light-emitting elements shown in Figures 12 and 13. an example of a method for manufacturing the light-emitting element shown in Figure 12. This is a cross-sectional view showing an example of a method for manufacturing the light-emitting element shown in Figure 17. This is a cross-sectional view showing an example of the configuration of a light-emitting element according to one embodiment of the present disclosure. This is a cross-sectional view showing an example of the configuration of a light-emitting device equipped with the light-emitting element shown in Figure 22. This is a cross-sectional view showing another example of the configuration of a light-emitting device equipped with the light-emitting element shown in Figure 22. This is a cross-sectional view showing an example of a method for manufacturing the light-emitting element shown in Figure 22. This is a cross-sectional view showing an example of the configuration of a light-emitting element according to one embodiment of the present disclosure. This is a cross-sectional view showing an example of a method for manufacturing the light-emitting element shown in Figure 26. This is a cross-sectional view showing an example of the configuration of a light-emitting element according to one embodiment of the present disclosure.Figure 28 is a cross-sectional view showing an example of a method for manufacturing a light-emitting element. It is a schematic diagram showing an example of the configuration of a display device according to this disclosure.

[0011] [Embodiment 1] (Configuration of a light-emitting element) Figure 1 is a cross-sectional view showing an example of the configuration of a light-emitting element according to one embodiment of the present disclosure. Figure 2 is a cross-sectional view showing another example of the configuration of a light-emitting element according to one embodiment of the present disclosure. As shown in Figures 1 and 2, the light-emitting element ED according to the present disclosure comprises (i) an anode AN and a cathode CA, (ii) a light-emitting layer EML located between the anode AN and the cathode CA and containing a light-emitting quantum dot QD and a first ligand material L1 that can coordinate to the quantum dot QD, and (iii) an adjacent layer ADL located between the anode AN and the cathode CA and in contact with the light-emitting layer EML, wherein the adjacent layer ADL includes a matrix M2 containing a crosslinkable organic material and a second ligand material L2 encapsulated in the matrix M2. The second ligand material L2 may be selected such that it is diffusible into the light-emitting layer EML, for example, the matrix M2 may be selected so as not to react with the second ligand material L2.

[0012] The adjacent layer ADL may be formed on the upper surface of the light-emitting layer EML. With this configuration, the exposure of the light-emitting layer EML to chemicals and gases can be reduced by the adjacent layer ADL covering the upper surface of the light-emitting layer EML. By reducing exposure, the amount of the first ligand material L1 that leaches out from the light-emitting layer EML during the manufacturing of the light-emitting element ED can be reduced. It is preferable that the base material M2 is selected so as not to react with the first ligand material L1. Note that "upper surface" refers to the surface of the layer opposite to the substrate SB, which will be described later, and "lower surface" refers to the surface of the layer facing the substrate SB, which will be described later.

[0013] The light-emitting element ED may optionally include a charge functional layer located between the anode AN and the light-emitting layer EML, such as a hole transport layer HTL, a hole injection layer, and an electron blocking layer. The light-emitting element ED may optionally include a charge functional layer located between the cathode CA and the light-emitting layer EML, such as an electron transport layer ETL, an electron injection layer, and a hole blocking layer.

[0014] The light-emitting element ED may be formed on a substrate SB. In this disclosure, the direction from the substrate SB toward the light-emitting layer EML is defined as upward, upward, upward, or upward, and the direction from the light-emitting layer EML toward the substrate SB is defined as downward, downward, downward, or downward.

[0015] The second ligand material L2 is preferably a ligand material that can coordinate to quantum dots QD. For example, the first ligand material L1 and the second ligand material L2 may be organic ligand materials having the same functional group. For example, the first ligand material L1 and the second ligand material L2 may be the same inorganic ligand material.

[0016] The base material M2 may contain a photoresist as a crosslinkable organic material. This allows the adjacent layer ADL to act as an etching mask for the light-emitting layer EML, thereby reducing the number of manufacturing steps and manufacturing costs of the light-emitting element ED. The crosslinkable organic material contained in the base material M2 may be a negative-type photoresist.

[0017] Furthermore, to minimize the reaction between the base material M2 and the second ligand material L2, for example, a material that does not contain amine groups, thiol groups, or halogens as terminal groups in its molecular structure can be selected as the crosslinkable organic substance, and a material containing sulfo groups, carboxyl groups, or phosphate groups as terminal groups, or phosphine, can be selected as the second ligand material L2. With such a combination of base material M2 and second ligand material L2, the two materials do not react easily, and the second ligand material L2 is encapsulated within the base material M2 in a state that allows it to diffuse into the luminescent layer EML.

[0018] The adjacent layer ADL may have a charge blocking function. This allows the adjacent layer ADL to be used as an electron blocking layer or a hole blocking layer, thereby improving the carrier balance in the light-emitting layer EML. In this case, it is preferable that the electrical conductivity of the adjacent layer ADL is low, for example, 1 × 10⁻⁶ －６ It may be less than or equal to [S / m].

[0019] The adjacent layer ADL may have a charge transport function. This allows the adjacent layer ADL to be used as a hole transport layer HTL or an electron transport layer ETL, improving the charge transport efficiency to the light-emitting layer EML and the carrier balance in the light-emitting layer EML. In this case, it is preferable that the electrical conductivity of the adjacent layer ADL is high, for example, 1 × 10⁻⁶ －６ [S / m] Super 1×10 ６ It may be less than or equal to [S / m].

[0020] Figure 3 is a band diagram showing an example of the band structure of the light-emitting device shown in Figure 1. Figure 4 is a band diagram showing an example of the band structure of the light-emitting device shown in Figure 2. In Figures 3 and 4, the Fermi levels of the anode AN and cathode CA are shown by solid lines, and the band gaps of the hole transport layer HTL, light-emitting layer EML, adjacent layer ADL, and hole transport layer HTL are shown by rectangles. The band gap is the band gap between the valence band (VB) and the conduction band (CB). The bottom edge of the rectangle represents the highest occupied molecular orbital (HOMO), and the top edge of the rectangle represents the lowest unoccupied molecular orbital (LUMO).

[0021] In this disclosure, when the absolute value of the energy difference between two levels X and Y is greater than or equal to Z, and level X is located between level Y and the vacuum level, level X is said to be Z or more higher than level Y. When the absolute value of the energy difference between two levels X and Y is greater than or equal to Z, and level Y is located between level X and the vacuum level, level X is said to be Z or more lower than level Y. The highest occupied level and the lowest unoccupied level can be simultaneously measured by photoelectron molecular spectroscopy while drilling into the light-emitting element ED with an ion beam. Through this simultaneous measurement, the highest occupied level and the lowest unoccupied level of the adjacent layer ADL and the light-emitting layer EML can be determined, respectively.

[0022] As shown in Figure 3, when the adjacent layer ADL is located between the light-emitting layer EML and the cathode CA and acts as a hole-blocking layer, the electrical conductivity of the adjacent layer ADL is 1 × 10⁻⁶. －６The conductivity is less than or equal to [S / m], and it is preferable that the highest occupied energy level (HOMO) of the adjacent layer ADL is 0.1 [eV] or lower than the HOMO of the light-emitting layer EML. When the adjacent layer ADL is located between the light-emitting layer EML and the cathode CA and acts as an electron transport layer, the electrical conductivity of the adjacent layer ADL is 1 × 10⁻¹⁶. －６ It is preferable that the value is greater than [S / m] and the lowest air level (LUMO) of the adjacent layer ADL is 0.1 [eV] or higher than the LUMO of the light-emitting layer EML.

[0023] As shown in Figure 4, when the adjacent layer ADL is located between the light-emitting layer EML and the anode AN and acts as an electron blocking layer, the electrical conductivity of the adjacent layer ADL is 1 × 10⁻¹⁰. －６ It is preferable that the LUMO of the adjacent layer ADL is 0.1 [eV] or higher than that of the LUMO of the light-emitting layer EML. When the adjacent layer ADL is located between the light-emitting layer EML and the anode AN and acts as a hole transport layer, the electrical conductivity of the adjacent layer ADL is 1 × 10⁻¹⁶. －６ It is preferable that the HOMO of the adjacent layer ADL is greater than [S / m] and at least 0.1 [eV] lower than the HOMO of the light-emitting layer EML.

[0024] When the adjacent layer ADL acts as a charge transport layer, its thickness is preferably 1 nm or more, and preferably 20 nm or less. Because its thickness is 20 nm or less, electrons or holes can be injected into the light-emitting layer EML across the adjacent layer ADL. When the adjacent layer ADL acts as a charge blocking layer, its thickness is preferably 21 nm or more, and preferably 50 nm or less. Because its thickness is between 21 nm and 50 nm, the adjacent layer ADL can block charge transfer to the light-emitting layer EML, thereby controlling the carrier balance in the light-emitting layer EML.

[0025] (Liandant concentration distribution and deactivation) Figure 5 is a schematic diagram showing an example of the ligand concentration distribution in the light-emitting layer and adjacent layer shown in Figures 1 and 2. Figure 6 is a schematic diagram showing another example of the ligand concentration distribution in the light-emitting layer and adjacent layer shown in Figures 1 and 2. In Figures 5 and 6, the color density indicates the ligand concentration; darker or darker colors indicate a higher ligand concentration, while lighter or brighter colors indicate a lower ligand concentration.

[0026] As shown in Figure 5, the concentration of the second ligand material L2 in the adjacent layer ADL may decrease in the direction away from the interface BS between the adjacent layer ADL and the light-emitting layer EML. As shown in Figures 5 and 6, the concentration of the first ligand material L1 in the light-emitting layer EML may decrease in the direction away from the interface BS between the adjacent layer ADL and the light-emitting layer EML. As shown in Figure 5, the concentration of the second ligand material L2 in the adjacent layer ADL may increase in the direction away from the side surface of the adjacent layer ADL. The side surface P2 of the adjacent layer ADL may be deactivated.

[0027] In this disclosure, "deactivated" of an adjacent layer ADL means that, when the adjacent layer ADL is acting as a charge blocking layer, the electrical conductivity of that portion is 200% or more of the electrical conductivity of the other portions. "Deactivated" of an adjacent layer ADL means that, when the adjacent layer ADL is acting as a charge transport layer, the electrical conductivity of that portion is 50% or less of the electrical conductivity of the other portions. The distribution of electrical conductivity can be determined through evaluation methods that allow visualization of electrical conductivity, such as cross-sectional observation using current-AFM.

[0028] As shown in Figure 5, the concentration of the first ligand material L1 in the emissive layer EML may increase in the direction away from the side surface of the emissive layer EML. The side portion P1 of the emissive layer EML may be deactivated. In this disclosure, deactivation of a portion of the emissive layer EML means that the portion has lost its luminescence or that the fluorescence lifetime of the portion is 50% or less of the fluorescence lifetime of the other portions. The fluorescence lifetime distribution can be determined by microscopic fluorescence lifetime measurement.

[0029] Alteration of the side portions P2 and P1 of the adjacent layer ADL and the luminescent layer EML can lead to the deactivation of those side portions P2 and P1. Alteration can include changes in composition or chemical structure, for example. Therefore, when side portions P2 and P1 are altered, it can be presumed that they are deactivated. Alteration in continuous layers can be detected through chemical analysis.

[0030] The method for achieving such a ligand material concentration distribution will be described later.

[0031] (Source of Ligand Material) Part or all of the second ligand material L2 of the adjacent layer ADL may originate from the first ligand material L1 that has eluted from the light-emitting layer EML or the quantum dot layer QDL (see Figure 10), which is the precursor of the light-emitting layer EML, into the coating layer F1 (see Figure 10), which is the precursor of the adjacent layer ADL.

[0032] Some or all of the second ligand material L2 in the adjacent layer ADL may be supplied from the metal salt contained in the adjacent layer ADL. By migrating the second ligand material L2 from the adjacent layer ADL to the light-emitting layer EML, the ligand material can be replenished in the light-emitting layer EML during and after the manufacturing of the light-emitting element ED. The matrix M2 may contain the second ligand material L2 and a metal element that can form a salt with the second ligand material L2. It is beneficial that the metal element that can form a salt with the second ligand material L2 is also included in the quantum dot QD. The smaller the total number of different elements contained in the light-emitting layer EML and the adjacent layer ADL, the more stable the chemical composition of the light-emitting layer EML is. Furthermore, defects in the quantum dot QD can be reduced. For example, if the outermost layer of the quantum dot QD contains a zinc compound and the first ligand material L1 and second ligand material L2 are halogens, it is beneficial to add zinc halide to the adjacent layer ADL. This allows halide ions and zinc ions to migrate from the adjacent layer (ADL) to the light-emitting layer (EML), and the zinc ions can fill the zinc defects in the quantum dots (QD).

[0033] To facilitate the replenishment of ligand material to the light-emitting layer EML, the contact area of ​​the adjacent layer ADL with the light-emitting layer EML may be increased. For example, the upper surface of the light-emitting layer EML may be roughened, or cracks may be formed in the light-emitting layer EML so that the cracks divide the upper surface of the light-emitting layer EML. This increases the surface area of ​​the upper surface of the light-emitting layer EML, and also increases the contact area of ​​the adjacent layer ADL with the light-emitting layer EML.

[0034] A portion of the first ligand material L1 of the light-emitting layer EML may originate from the second ligand material L2 that has migrated from the adjacent layer ADL or the coating layer F1 (see Figure 10), which is a precursor to the adjacent layer ADL, to the light-emitting layer EML or the quantum dot layer QDL (see Figure 10), which is a precursor to the light-emitting layer EML.

[0035] (Configuration of the light-emitting device) Figures 7 to 9 are cross-sectional views showing examples of the configuration of a light-emitting device equipped with the light-emitting element shown in Figure 1. As shown in Figures 7 to 9, a light-emitting device LE according to one embodiment of the present disclosure comprises a first light-emitting element ED1, which is a light-emitting element ED according to one embodiment of the present disclosure and includes a first light-emitting element EM1 that emits a first color as a light-emitting layer EML, and a second light-emitting element ED2, which is a light-emitting element ED according to one embodiment of the present disclosure and includes a second light-emitting layer EM2 that emits a second color as a light-emitting layer EML. The first and second colors may be different primary colors from each other. The first and second colors may be selected from the three primary colors of light: red, green, and blue.

[0036] The light-emitting device LE may further include a third light-emitting element ED3, which is a light-emitting element ED according to one embodiment of the present disclosure, and includes a third light-emitting layer EM3 that emits a third color as a light-emitting layer EML. The third color may be a primary color different from the first and second colors. The third color may be selected from the three primary colors of light: red, green, and blue.

[0037] As adjacent layer ADL, the first light-emitting element ED1 may have adjacent layer AD1, the second light-emitting element ED2 may have adjacent layer AD2, and the third light-emitting element ED3 may have adjacent layer AD3.

[0038] The charge functional layers such as the hole transport layer HEL and the electron transport layer ETL of the first to third light emitting elements ED1 to ED3 may be connected to each other. One of the anode AN and the cathode CA of the first to third light emitting elements ED1 to ED3 may be connected to each other, and may be a so-called common electrode. The other of the anode AN and the cathode CA of the first to third light emitting elements ED1 to ED3 may be island-shaped electrodes separated from each other.

[0039] As shown in FIG. 8, a part of the first light-emitting layer EM1 may overlap the second light-emitting layer EM2 in a plan view. Compared with a configuration without an adjacent layer, according to the configuration of the present disclosure including the adjacent layer ADL, the area where the first light-emitting layer EM1 is in direct contact with the second light-emitting layer EM2 is smaller. Therefore, film roughness caused by dissolution and mixing of the first light-emitting layer EM1 and the second light-emitting layer EM2 can be reduced. Similarly, another part of the first light-emitting layer EM1 may overlap the third light-emitting layer EM3 in plan view, and a part of the second light-emitting layer EM2 may overlap the third light-emitting layer EM3 in plan view.

[0040] The second ligand material L2 of the first light emitting element ED1 and the second ligand material L2 of the second light emitting element ED2 may be different from each other. The second ligand material L2 of the third light emitting element ED3 may be different from at least one of the second ligand material L2 of the first light emitting element ED1 and the second ligand material L2 of the second light emitting element ED2.

[0041] As shown in FIG. 9, the light-emitting device LE may further include a bank BK located between the first light-emitting element ED1 and the second light-emitting element ED2. The bank BK may be located between the first light-emitting element ED1 and the third light-emitting element ED3, and may be located between the second light-emitting element ED2 and the third light-emitting element ED3.

[0042] (Method for Manufacturing Light-Emitting Element) FIG. 10 is a cross-sectional view showing an example of a method for manufacturing the light-emitting element shown in FIG. 1 and FIG. 2. As shown in FIG. 10, the method for manufacturing the light-emitting element ED according to the first embodiment includes a step of forming a light-emitting layer EML containing a light-emitting quantum dot QD and a first ligand material L1 capable of coordinating to the quantum dot QD (step S10), and a step of forming an adjacent layer ADL that is in contact with the light-emitting layer EML and contains a base material M2 containing a crosslinkable organic substance and a second ligand material L2 encapsulated in the base material M2 (step S20).

[0043] The step of forming the light-emitting layer EML includes a step of forming a planar quantum dot layer QDL containing the quantum dot QD and the first ligand material L1 (step S14), and a step of forming the light-emitting layer EML by patterning the quantum dot layer QDL (step S16).

[0044] The step of forming the adjacent layer ADL may include a step of forming a planar coating layer F1 containing a base material M2 containing a crosslinkable organic substance and a second ligand material L2 encapsulated in the base material M2 on the planar quantum dot layer QDL (step S21), and a step of forming the adjacent layer ADL from the coating layer F1 by photolithography. Then, the quantum dot layer QDL may be patterned using the adjacent layer ADL as a mask. Dry etching or wet etching may be used for this patterning. A portion of the quantum dot layer QDL protected by the adjacent layer ADL remains as the light-emitting layer EML after the etching treatment, and other portions are removed by the etching treatment.

[0045] Some or all of the second ligand material L2 in the coating layer F1 may originate from the first ligand material L1 eluted from the quantum dot layer QDL into the coating layer F1. Some or all of the second ligand material L2 in the coating layer F1 may be initially contained in the liquid applied to form the coating layer F1. For example, a liquid containing a metal salt containing the second ligand material L2 and a base material M2 (or a precursor of the base material M2) may be applied onto the quantum dot layer QDL. The coating layer F1 may contain the second ligand material L2 at a high concentration, and some of the second ligand material L2 in the coating layer F1 or the adjacent layer ADL may migrate to the quantum dot layer QDL or the light-emitting layer EML to become the first ligand material L1. This allows for the formation of a ligand material concentration distribution in the light-emitting layer EML and the adjacent layer ADL, for example, as shown in Figure 6.

[0046] The process of forming an adjacent layer ADL from a coating layer F1 using photolithography technology includes a step of irradiating the coating layer F1 with ultraviolet light (UV) or the like through a photomask PM (step S22) and a step of etching the coating layer F1, which is a so-called development process (step S23). When the coating layer F1 contains a negative-type photoresist, the exposed portion of the coating layer F1 remains as the adjacent layer ADL after the development process, and the unexposed portion of the coating layer F1 is removed by the development process.

[0047] Figure 11 is a cross-sectional view showing an example of a method for manufacturing the light-emitting element shown in Figures 1 and 2. As shown in Figure 11, after patterning the light-emitting layer EML, the concentration of the first ligand material L1 on the side P1 of the light-emitting layer EML may be reduced by a rinsing treatment (step S30). In the side P1, excess first ligand material L1 that is free and not coordinated to the quantum dot QD dissolves into the rinsing solution RS. Furthermore, a portion of the first ligand material L1 that is coordinated to the quantum dot QD may be released from the quantum dot QD and dissolve into the rinsing solution RS. The first ligand material L1 that has dissolved into the rinsing solution RS is removed together with the rinsing solution RS. The side P1 of the light-emitting layer EML may be deactivated due to alteration by the etching solution or the rinsing solution RS.

[0048] During the rinsing process, the second ligand material L2 also elutes from the adjacent layer ADL. The side portion P2 of the adjacent layer ADL may be deactivated due to alteration by the etching solution or rinsing solution RS. The elution of the first and second ligand materials L1 and L2 allows for the formation of a ligand material concentration distribution in the luminescent layer EML and the adjacent layer ADL, for example, as shown in Figure 5.

[0049] When rinsing an EML (emissive luminescence layer) after patterning it by wet etching, the solvents used for the etching solution and the rinsing solution RS have different polarities. The etching solution is prepared so that both the quantum dots QD (coordinated to the first ligand material L1) and the free first ligand material L1 are easily dispersed in the etching solution. On the other hand, the rinsing solution RS is prepared so that the quantum dots QD (coordinated to the first ligand material L1) are difficult to disperse in the rinsing solution RS, while the free first ligand material L1 is easily dispersed in the rinsing solution RS.

[0050] For example, oleic acid alone exhibits surface activity and disperses readily in both highly polar and low-polarity to non-polar solvents. On the other hand, quantum dots (QD) coordinated to oleic acid are poorly dispersed in highly polar solvents and readily dispersed in low-polarity to non-polar solvents. This is because oleic acid coordinates to quantum dots (QD) via its carboxyl group, and the alkyl group of oleic acid determines the dispersibility of the coordinated quantum dots (QD). Therefore, when using oleic acid as the first ligand material L1, a low-polarity to non-polar solvent is used in the etching solution, and a polar solvent is used in the rinsing solution RS.

[0051] As described above, the rinsing process can remove the free first ligand material L1 from the side P1 of the light-emitting layer EML. The first ligand material L1 coordinated to the quantum dot QD actually undergoes repeated adsorption and desorption to the quantum dot QD due to factors such as temperature energy. Therefore, a portion of the first ligand material L1 coordinated to the quantum dot QD may be released from the quantum dot QD and elute into the rinsing solution RS. For this reason, the rinsing process also removes a portion of the first ligand material L1 coordinated to the quantum dot QD.

[0052] The manufacturing method according to this embodiment 1 is not limited to a method of forming a concentration gradient of the first and second ligand materials L1 and L2 by rinsing. In addition to / instead of rinsing, the concentration gradient of the first and second ligand materials L1 and L2 may be formed in an etching process for patterning the light-emitting layer EML.

[0053] As shown in Figure 1, when forming a light-emitting element ED in a sequential structure in which the anode AN is located between the circuit board SB and the cathode CA, the substrate SB is prepared, and the anode AN (and optionally a charge functional layer) is formed on the substrate SB. Then, the aforementioned steps S10 and S20 (and optionally step S30) are performed. Next, the cathode CA (and optionally a charge functional layer) is formed.

[0054] As shown in Figure 2, when forming a light-emitting element ED in an inverted structure where the cathode CA is located between the circuit board SB and the anode AN, a substrate SB is prepared, and the cathode CA (and optionally a charge functional layer) is formed on the substrate SB. Then, steps S10 and S20 described above, and optionally step S30 described above are performed. Next, the anode AN (and optionally a charge functional layer) is formed.

[0055] (Method for Manufacturing a Light-Emitting Device) An example of a method for manufacturing the light-emitting device LE according to this embodiment 1 includes the step of forming the first to third light-emitting elements ED1 to ED3 on a substrate SB. As shown in Figures 7 to 9, if the light-emitting device LE has a forward structure, the anodes AN of the first to third light-emitting elements ED1 to ED3 may be formed on the substrate SB, steps S10 and S20 may be repeated multiple times, and then the cathodes CN of the first to third light-emitting elements ED1 to ED3 may be formed. If the light-emitting device LE has an inverted structure, the cathodes CN of the first to third light-emitting elements ED1 to ED3 may be formed on the substrate SB, steps S10 and S20 may be repeated multiple times, and then the anodes AN of the first to third light-emitting elements ED1 to ED3 may be formed.

[0056] When rinsing the first to third light-emitting layers EM1 to EM3, step S30 may be executed after each execution of steps S10 and S20, or step S30 may be executed after repeating steps S10 and S20 multiple times.

[0057] [Embodiment 2] (Configuration of the light-emitting element) Figure 12 is a cross-sectional view showing an example of the configuration of a light-emitting element ED according to one embodiment of the present disclosure. Figure 13 is a cross-sectional view showing another example of the configuration of a light-emitting element ED according to one embodiment of the present disclosure. Figure 14 is a cross-sectional view showing yet another example of the configuration of a light-emitting element ED according to one embodiment of the present disclosure. As shown in Figures 12 to 14, the adjacent layer ADL according to this embodiment 2 is in contact with the upper and side surfaces of the light-emitting layer EML. With these configurations, by having the adjacent layer ADL cover the upper and side surfaces of the light-emitting layer EML, the amount of first ligand material L1 eluting from the light-emitting layer EML can be further reduced, and the ligand material can be further replenished in the light-emitting layer EML.

[0058] As shown in Figure 13, the adjacent layer ADL according to this second embodiment may be in contact with the upper and lower surfaces of the light-emitting layer EML. In this case, the adjacent layer ADL includes an upper layer A1 that is in contact with the upper and side surfaces of the light-emitting layer EML, and a lower layer A2 that is in contact with the lower surface of the light-emitting layer EML. With this configuration, by having the adjacent layer ADL cover the upper, side and lower surfaces of the light-emitting layer EML, the amount of the first ligand material L1 that elutes from the light-emitting layer EML can be further reduced, and the ligand material can be further replenished in the light-emitting layer EML.

[0059] As shown in Figure 14, the light-emitting layer EML according to this second embodiment may have a recess formed on its upper surface. The recess provided on the upper surface of the light-emitting layer EML may penetrate the light-emitting layer EML or divide the light-emitting layer EML. The adjacent layer ADL according to this second embodiment also covers the sides of the recess, and the adjacent layer ADL is in contact with the sides of the recess. The surface area of ​​the light-emitting layer EML is increased by the irregularities, and the area in contact between the adjacent layer ADL and the light-emitting layer EML is also increased, making it easier to replenish the ligand material to the light-emitting layer EML. The configuration example shown in Figure 14 can be combined with the configuration example shown in Figure 13.

[0060] (Configuration of the light-emitting device) Figures 15 to 19 are cross-sectional views showing an example of the configuration of a light-emitting device equipped with the light-emitting elements shown in Figures 12 and 13, respectively. As shown in Figures 15 to 19, the light-emitting device LE according to this embodiment 2 comprises a first light-emitting element ED1 and a second light-emitting element ED2, and may optionally include a third light-emitting element ED3. In each light-emitting element of the light-emitting device LE according to this embodiment 2, irregularities may be formed on the upper surface of the light-emitting layer, as shown in Figure 14.

[0061] As shown in Figure 15, the adjacent layer AD1 of the first light-emitting element ED1 may be separated from the adjacent layer AD2 of the second light-emitting element ED2. The adjacent layer AD3 of the third light-emitting element ED3 may be separated from at least one of the adjacent layer AD1 of the first light-emitting element ED1 and the adjacent layer AD2 of the second light-emitting element ED2.

[0062] As shown in Figures 16 and 17, the light-emitting device LE may include a gap layer GP1 that connects to the adjacent layer AD1 of the first light-emitting element ED1 and the adjacent layer AD2 of the second light-emitting element ED2, and is located in the gap between the first light-emitting layer EM1 and the second light-emitting layer EM2. The gap layer GP1 between the first light-emitting layer EM1 and the second light-emitting layer EM2 may be approximately the same thickness as the portion of the adjacent layer AD1 of the first light-emitting element ED1 that is in contact with the upper surface of the first light-emitting layer EM1, as shown in Figure 16, or it may be greater than the thickness of the portion of the adjacent layer AD1 that is in contact with the upper surface of the first light-emitting layer EM1, as shown in Figure 17. As shown in Figure 17, if the thickness of the gap layer GP1 is large, the gap layer GP1 can function as a bank that reduces the leakage current between the first light-emitting layer EM1 and the second light-emitting layer EM2.

[0063] When the gap layer GP1 functions as a bank, the thickness of the gap layer GP1 is preferably 50 nm or more, and more preferably 100 nm or more. When the gap layer GP1 functions as a bank, the thickness of the gap layer GP1 is preferably 200% or more, and more preferably 500% or more, of the thickness of the portion of the adjacent layer AD1 of the first light-emitting element ED1 that is in contact with the upper surface of the first light-emitting layer EM1. The thickness of the above portion of the adjacent layer AD1 of the first light-emitting element ED1 is equal to or greater than the thickness of the portion of the adjacent layer AD2 of the second light-emitting element ED2 that is in contact with the upper surface of the second light-emitting layer EM2. When the gap layer GP1 functions as a bank, the thickness of the gap layer GP1 is preferably 200% or more, and more preferably 500% or more, of the thickness of the first light-emitting layer EM1. The thickness of the first light-emitting layer EM1 may be equal to or greater than the thickness of the second light-emitting layer EM2.

[0064] The light-emitting device LE may include a gap layer GP2 connected to the adjacent layer AD1 of the first light-emitting element ED1 and the adjacent layer AD3 of the third light-emitting element ED3, and located in the gap between the first light-emitting layer EM1 and the third light-emitting layer EM3. The light-emitting device LE may also include a gap layer GP3 connected to the adjacent layer AD2 of the second light-emitting element ED2 and the adjacent layer AD3 of the third light-emitting element ED3, and located in the gap between the second light-emitting layer EM2 and the third light-emitting layer EM3.

[0065] As shown in Figure 18, the adjacent layer AD1 of the first light-emitting element ED1 may include a portion that contacts the lower surface of the first light-emitting layer EM1 of the first layer B1, and a portion that contacts the upper and side surfaces of the first light-emitting layer EM1 of the second layer B2. Alternatively, as shown in Figure 19, the adjacent layer AD1 of the first light-emitting element ED1 may include a portion that contacts the upper and side surfaces of the first light-emitting layer EM1 of the second layer B2.

[0066] As shown in Figures 18 and 19, the adjacent layer AD2 of the second light-emitting element ED2 may include a portion that contacts the lower surface of the second light-emitting layer EM2 of the second layer B2, and a portion that contacts the upper and side surfaces of the second light-emitting layer EM2 of the third layer B3. The adjacent layer AD3 of the third light-emitting element ED3 may include a portion that contacts the lower surface of the third light-emitting layer EM3 of the third layer B3, and a portion that contacts the upper and side surfaces of the third light-emitting layer EM3 of the fourth layer B4.

[0067] (Method for Manufacturing a Light-Emitting Device) Figure 20 is a cross-sectional view showing an example of the method for manufacturing a light-emitting device shown in Figure 12. As shown in Figure 20, the method for manufacturing a light-emitting device ED according to this embodiment 2 includes the steps of forming a light-emitting layer EML containing light-emitting quantum dots QD and a first ligand material L1 that can coordinate to the quantum dots QD (step S10), and forming an adjacent layer ADL that is in contact with the upper surface of the light-emitting layer EML and contains a base material M2 containing a crosslinkable organic material and a second ligand material L2 encapsulated in the base material M2 (step S20).

[0068] The process of patterning and forming the light-emitting layer EML may include the steps of forming a planar coating layer F2 containing a photoresist (step S11), forming a template layer TL from the coating layer F2 by photolithography, forming a planar quantum dot layer QDL on the template layer TL (step S14A), and forming the light-emitting layer EML by patterning the quantum dot layer QDL (step S16A). After patterning and forming the light-emitting layer EML from the quantum dot layer QDL, an adjacent layer ADL is formed.

[0069] The process of forming a template layer TL from a coating layer F2 using photolithography technology includes a step of irradiating the coating layer F2 with ultraviolet light (UV) or the like through a photomask PM1 (step S12) and a step of etching the coating layer F2, which is a so-called development process (step S13). When the coating layer F2 contains a positive-type photoresist, the exposed portion of the coating layer F2 is removed by the development process, and the unexposed portion of the coating layer F2 remains as the template layer TL after the development process. Then, by removing the template layer TL, the portion of the quantum dot layer QDL on the template layer TL is removed, and the remaining portion of the quantum dot layer QDL remains as the light-emitting layer EML.

[0070] The step of forming the adjacent layer ADL may include a step of forming a planar coating layer F1 containing a base material M2 containing a crosslinkable organic material and a second ligand material L2 encapsulated in the base material M2, so as to cover the upper and side surfaces of the light-emitting layer EML (step S21A), and a step of forming the adjacent layer ADL from the coating layer F1 by photolithography. The step of forming the adjacent layer ADL from the coating layer F1 by photolithography includes a step of irradiating the coating layer F1 with ultraviolet light (UV) or the like through a photomask PM2 (step S22), and a step of etching the coating layer F1, a so-called developing process (step S23). Alternatively, the coating layer F1 may remain planar without patterning, as shown in the adjacent layer ADL and gap layer GPL in Figure 16, and as shown in the second to fourth layers B2 to B4 in Figures 18 and 19.

[0071] Figure 21 is a cross-sectional view showing an example of a method for manufacturing the light-emitting element shown in Figure 17. As shown in Figure 21, the method for manufacturing the light-emitting element ED according to this second embodiment involves first patterning and forming a light-emitting layer EML from a quantum dot layer QDL, and then forming a planar coating layer F1 containing a base material M2 containing a crosslinkable organic material and a second ligand material L2 embedded in the base material M2, so as to cover the upper and side surfaces of the light-emitting layer EML (step S21A). Next, a step of irradiating the coating layer F1 with ultraviolet light (UV) or the like (step S22A) and a step of etching the coating layer F1, a so-called developing process (step S23A), are performed. This forms an adjacent layer ADL and a gap layer GPL connected to the adjacent layer ADL from the coating layer F1.

[0072] In the process of irradiating the coating layer F1 with ultraviolet UV light, it is preferable to expose the coating layer F1 through the photomask PM3 such that the degree of crosslinking of the portion of the coating layer F1 intended to become the adjacent layer ADL is lower than the degree of crosslinking of the portion intended to become the gap layer GPL. The higher the degree of crosslinking of a portion of the coating layer F1, the greater the thickness of that portion remaining after the development process. Therefore, the gap layer GPL is thicker than the adjacent layer ADL and can function as a bank. For example, when the coating layer F1 contains a negative-type photoresist, it is beneficial that the transmittance of region A3 of the photomask PM3 corresponding to the adjacent layer ADL is smaller than the transmittance of region A4 corresponding to the gap layer GPL. A gray tone mask or a halftone mask may be used for the photomask PM3.

[0073] [Embodiment 3] (Configuration of a light-emitting element) Figure 22 is a cross-sectional view showing an example of the configuration of a light-emitting element according to one embodiment of the present disclosure. As shown in Figure 22, the light-emitting element ED according to this embodiment 3 includes a charge transport layer CTL that is in contact with the lower surface of the light-emitting layer EML. The charge transport layer CTL may overlap and substantially coincide with the light-emitting layer EML in a plan view and may have photocrosslinking properties. Preferably, the charge transport layer CTL overlaps with the light-emitting region of the light-emitting layer EML in a plan view. The side portion P3 of the charge transport layer CTL may be deactivated, similar to the side portions P1 and P2 of the light-emitting layer EML and the adjacent layer ADL.

[0074] (Configuration of the light-emitting device) Figures 23 and 24 are cross-sectional views showing an example of the configuration of a light-emitting device equipped with the light-emitting element shown in Figure 22. As shown in Figures 23 and 24, the light-emitting device LE according to this embodiment 3 comprises a first light-emitting element ED1 and a second light-emitting element ED2, and may optionally include a third light-emitting element ED3. The light-emitting device LE according to this embodiment 3 may include a first charge transport layer CT1 located below the first light-emitting layer EM1, and a second charge transport layer CT2 located below the second light-emitting layer EM2 and separated from the first charge transport layer CT1.

[0075] The first charge transport layer CT1 and the second charge transport layer CT2 may each have photocrosslinking properties. The sides P31 and P32 of the first charge transport layer CT1 and the second charge transport layer CT2 may be deactivated. By deactivating the sides P31 and P32, the leakage current between the first light-emitting element ED1 and the second light-emitting element ED2 can be reduced.

[0076] The light-emitting device LE may further include a third charge transport layer CT3 located beneath the third light-emitting layer EM3 and separated from the first charge transport layer CT1 and the second charge transport layer CT2. The third charge transport layer CT3 may also be photocrosslinkable, and the side portion P33 of the third charge transport layer CT3 may be deactivated.

[0077] As shown in Figure 23, the light-emitting device LE may include a first charge-blocking layer CB1 formed from the same layer as a charge transport layer that contacts the lower surface of the light-emitting layer of another light-emitting element, on the adjacent layer AD1 of the first light-emitting element ED1. The first charge-blocking layer CB1 may overlap and substantially coincide with the first light-emitting layer EM1 in a plan view. The light-emitting device LE may include a second charge-blocking layer CB2 formed from the same layer as a charge transport layer that contacts the lower surface of the light-emitting layer of another light-emitting element, on the adjacent layer AD2 of the second light-emitting element ED2. The second charge-blocking layer CB2 may overlap and substantially coincide with the second light-emitting layer EM2 in a plan view.

[0078] For example, the first and second charge blocking layers CB1 and CB2 in the first and second light-emitting elements ED1 and ED2 may be formed from the same layer as the third charge transport layer CT3 in the third light-emitting element ED3. When the light-emitting device LE has a forward structure, the first to third charge transport layers CT1 to CT3 each have hole transport properties, and the first and second charge blocking layers CB1 and CB2 each have electron blocking properties.

[0079] (Method for Manufacturing a Light-Emitting Device) Figure 25 is a cross-sectional view showing an example of the method for manufacturing a light-emitting device shown in Figure 22. As shown in Figure 25, the method for manufacturing a light-emitting device ED according to this embodiment 3 includes the steps of: forming a light-emitting layer EML containing light-emitting quantum dots QD and a first ligand material L1 that can coordinate to the quantum dots QD (step S10); forming an adjacent layer ADL that is in contact with the light-emitting layer EML and includes a base material M2 containing a crosslinkable organic material and a second ligand material L2 encapsulated in the base material M2 (step S20); and further including the step of forming a charge transport layer CTL that is in contact with the lower surface of the light-emitting layer EML (step S40).

[0080] The process of forming the charge transport layer CTL includes the steps of forming a planar underlayer F3 having charge functionality (step S44) and forming the charge transport layer CTL by patterning the underlayer F3 (step S46). When patterning and forming the charge transport layer CTL from the underlayer F3, the side portion P3 of the charge transport layer CTL may be deactivated by side etching.

[0081] The process of forming the light-emitting layer EML includes the steps of laminating a planar quantum dot layer QDL on a base layer F3 (step S14B) and forming the light-emitting layer EML by patterning the quantum dot layer QDL (step S16). When patterning and forming the light-emitting layer EML from the quantum dot layer QDL, the side portion P1 of the light-emitting layer EML may be deactivated by side etching.

[0082] The process of forming the adjacent layer ADL may include a step of forming a planar coating layer F1 on a planar quantum dot layer QDL, which includes a base material M2 containing a crosslinkable organic material and a second ligand material L2 encapsulated in the base material M2 (step S21), and a step of forming the adjacent layer ADL from the coating layer F1 by photolithography. The step of forming the adjacent layer ADL from the coating layer F1 by photolithography includes a step of irradiating the coating layer F1 with ultraviolet UV light or the like through a photomask PM (step S22) and a step of etching the coating layer F1, a so-called developing process (step S23). The quantum dot layer QDL and the base layer F3 may then be patterned together using the adjacent layer ADL as a mask. The portion of the quantum dot layer QDL and the base layer F3 protected by the adjacent layer ADL remains as an emissive layer EML after the etching process, and the other portions are removed by the etching process. This patterning process forms an EML (emissive emission layer) from the quantum dot layer (QDL) and a CTL (charge transport layer) from the underlying layer (F3).

[0083] In methods where the base layer F3 is not patterned together with the quantum dot layer QDL, residue originating from the quantum dot layer QDL on top of the base layer F3 may remain in regions that do not overlap with the light-emitting layer EML in a plan view. This residue can cause problems in color mixing and carrier injection. On the other hand, according to the method of this embodiment 3, since the base layer F3 is patterned together with the quantum dot layer QDL, no residue originating from the quantum dot layer QDL remains.

[0084] The base layer F3 may have photocrosslinking properties. When both the coating layer F1 and the base layer F3 contain a negative-type photoresist, the corresponding portion of the base layer F3 can be cured by exposure along with the portion of the coating layer F1. The exposed portions of the coating layer F1 and the base layer F3 remain as the adjacent layer ADL and the charge transport layer CTL, respectively, while the unexposed portions of the coating layer F1 and the base layer F3 are removed.

[0085] The manufacturing method for the light-emitting element ED according to this third embodiment may further involve a rinsing process (step S30) after patterning the light-emitting layer EML, similar to the first embodiment described above. The rinsing process, or both the side portion P1 of the light-emitting layer EML and / or the side portion P3 of the charge transport layer CTL, may be deactivated.

[0086] [Embodiment 4] (Configuration of Light-Emitting Device) Figure 26 is a cross-sectional view showing an example of the configuration of a light-emitting device according to one embodiment of the present disclosure. As shown in Figure 26, the light-emitting layer EML according to this embodiment 4 includes an inorganic medium M1 located around the quantum dot QD. The inorganic medium M1 may be an inorganic semiconductor compound such as zinc sulfide (ZnS), or an inorganic polymer such as a silicon-based polymer having siloxane bonds. The inorganic medium M1 may include at least one selected from the group consisting of alkoxysilanes, polysilazanes, and polysiloxanes. The inorganic medium M1 can improve the etching resistance of the light-emitting layer EML.

[0087] The first ligand material L1 included in the light-emitting layer EML according to this fourth embodiment is preferably an inorganic ligand such as a halogen. By making the light-emitting layer EML out of an inorganic material, the service life and reliability of the light-emitting layer EML can be improved. The configuration in which the light-emitting layer EML includes an inorganic medium M1 is applicable to the configurations according to embodiments 1 to 3 described above.

[0088] (Method for Manufacturing a Light-Emitting Device) Figure 27 is a cross-sectional view showing an example of the method for manufacturing a light-emitting device shown in Figure 26. As shown in Figure 27, the process for forming the light-emitting layer EML according to this embodiment 4 includes the steps of forming a planar quantum dot layer QDL containing quantum dots QD, a precursor PR of the inorganic medium M1, and a first ligand material L1 (step S14C), and forming the light-emitting layer EML by patterning the quantum dot layer QDL (step S16C).

[0089] The precursor PR of the inorganic medium M1 can react with each other to form the inorganic medium M1 through exposure or calcination.

[0090] For example, when the inorganic medium M1 is zinc sulfide, the precursor PR may contain at least one of zinc acetate, zinc nitrate, and zinc halide as a zinc source, and at least one of xanthogenic acid, thiourea, N-methylthiourea, 1,3-dimethylthiourea, N,N'-dimethylthiourea, tetramethylthiourea, and thioacetamide as a sulfur source. Alternatively, when the inorganic medium M1 is zinc sulfide, the precursor PR may also contain a metal complex coordinated to zinc with xanthogenic acid, thiourea, N-methylthiourea, 1,3-dimethylthiourea, N,N'-dimethylthiourea, tetramethylthiourea, or thioacetamide. The decomposition temperature of xanthogenic acid is approximately 200 degrees Celsius, and it is easily thermally decomposed.

[0091] For example, when the inorganic medium M1 is a silicon-based polymer, the precursor PR may contain 3-(mercaptopropyl)trimethoxysilane (MPS) and / or tetramethyl orthosilicate (TMOS).

[0092] The process of forming a planar quantum dot layer (QDL) may include the steps of: preparing a dispersion solution DS in which quantum dots (QD), a precursor PR of an inorganic medium M1, and a first ligand material L1 are dispersed in a solvent (step S141); applying the dispersion solution DS to a substrate (step S142); and forming the quantum dot layer (QDL) by drying the applied dispersion solution DS (step S143).

[0093] The process of forming an EML (emissive emission layer) by patterning a quantum dot layer (QDL) may include a step of irradiating the quantum dot layer (QDL) with ultraviolet light (UV) or the like through a photomask (PM) (step S161), and a step of etching the quantum dot layer (QDL), which is a so-called development process (step S162). The exposed portion of the quantum dot layer (QDL) remains as the EML after the development process, and the unexposed portion of the quantum dot layer (QDL) is removed by the development process.

[0094] The exposure of the quantum dot layer (QDL) may be performed together with the exposure of the coating layer F1 laminated on the quantum dot layer (step S22). The development of the quantum dot layer (QDL) may be performed together with the development of the coating layer F1 laminated on the quantum dot layer (step S23). After the development of the quantum dot layer (QDL), the light-emitting layer (EML) may be calcined to further advance the reaction of the precursor PR in the light-emitting layer (EML).

[0095] The process of forming an emissive layer (EML) by patterning a quantum dot layer (QDL) may be carried out without reacting the precursor PR when patterning the emissive layer (EML) from the quantum dot layer (QDL), and the precursor PR may become an inorganic medium (M1) by firing and / or exposure after patterning.

[0096] In either case, the light-emitting layer EML according to this embodiment 4 includes an inorganic medium M1 located around the quantum dot QD, and optionally includes a precursor PR of the inorganic medium M1.

[0097] [Embodiment 5] (Configuration of a light-emitting element) Figure 28 is a cross-sectional view showing an example of the configuration of a light-emitting element according to one embodiment of the present disclosure. As shown in Figure 28, the light-emitting layer EML according to this embodiment 5 includes a crosslinkable organic medium M4 located around the quantum dots QD. The crosslinkable organic medium M4 may be a positive-type photoresist. The organic medium M4 can improve the etching resistance of the light-emitting layer EML.

[0098] The configuration in which the light-emitting layer EML includes an organic medium M4 is applicable to the configurations described in Embodiments 1 to 3 above.

[0099] (Method for Manufacturing a Light-Emitting Device) Figure 29 is a cross-sectional view showing an example of the method for manufacturing a light-emitting device shown in Figure 28. As shown in Figure 29, the process for forming the light-emitting layer EML according to this embodiment 5 includes the steps of forming a planar quantum dot layer QDL containing quantum dots QD, an uncrosslinked organic medium M4, and a first ligand material L1 (step S14D), and forming the light-emitting layer EML by patterning the quantum dot layer QDL (step S16D). The uncrosslinked organic medium M4 is crosslinked by either exposure or firing.

[0100] The process of forming an EML (emissive emission layer) by patterning a quantum dot layer (QDL) may include a step of irradiating the quantum dot layer (QDL) with ultraviolet light (UV) or the like through a photomask (PM) (step S161), and a step of etching the quantum dot layer (QDL), which is a so-called development process (step S162). The exposed portion of the quantum dot layer (QDL) remains as the EML after the development process, and the unexposed portion of the quantum dot layer (QDL) is removed by the development process.

[0101] The exposure of the quantum dot layer (QDL) may be performed together with the exposure of the coating layer F1 laminated on the quantum dot layer (step S22). The development of the quantum dot layer (QDL) may be performed together with the development of the coating layer F1 laminated on the quantum dot layer (step S23). After the development of the quantum dot layer (QDL), the light-emitting layer (EML) may be fired to further advance the crosslinking of the organic medium (M4).

[0102] The process of forming an emissive layer (EML) by patterning a quantum dot layer (QDL) may be modified by not crosslinking the organic medium M4 when patterning the emissive layer (EML) from the quantum dot layer (QDL), and instead crosslinking the organic medium M4 by firing and / or exposure after patterning.

[0103] The light-emitting layer EML according to this 5th embodiment is advantageous if it is photocrosslinkable. The light-emitting layer EML includes a photocrosslinkable organic medium M3 located around the quantum dots QD.

[0104] [Embodiment 6] (Configuration of Display Device) Figure 30 is a schematic diagram showing an example of the configuration of a display device according to the present disclosure. As shown in Figure 30, a display device DP according to one embodiment of the present disclosure includes a light-emitting element ED according to one embodiment of the present disclosure. The display device DP may also include a light-emitting device LE according to one embodiment of the present disclosure.

[0105] The display device DP comprises, for example, a display area DA provided with a plurality of subpixels PX, and a frame area NA provided with a drive circuit DC for driving the display area DA, wherein at least one of the plurality of subpixels PX includes a light-emitting element ED. Alternatively, the display device DP may comprise a liquid crystal device and a light-emitting device LE as a backlight.

[0106] This disclosure is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of this disclosure. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

[0107] AD1 Adjacent layer of the first light-emitting element AD2 Adjacent layer of the second light-emitting element ADL Adjacent layer AN Anode BS Interface between the light-emitting layer and the adjacent layer CA Cathode CTL Charge transport layer CT1 First charge transport layer CT2 Second charge transport layer DS Dispersion solution ED Light-emitting element ED1 First light-emitting element ED2 Second light-emitting element EM1 First light-emitting layer EM2 Second light-emitting layer EML Light-emitting layer F1 Coating layer F2 Coating layer F3 Underlayment GP1, GP2, GP3, GPL Gap layer L1 First ligand material L2 Second ligand material LE Light-emitting device M1 Inorganic medium M2 Base material M3 Organic medium P1 Side of the light-emitting layer P2 Side of the adjacent layer P3 Side of the charge transport layer P31 Side of the first charge transport layer P32 Side of the second charge transport layer P33 Side of the third charge transport layer PR Precursor of inorganic medium QD Quantum dot QDL Quantum dot layer

Claims

1. A light-emitting element comprising: an anode and a cathode; a light-emitting layer located between the anode and the cathode and containing a light-emitting quantum dot and a first ligand material capable of coordinating to the quantum dot; and an adjacent layer located between the anode and the cathode and in contact with the light-emitting layer, wherein the adjacent layer comprises a matrix material containing a crosslinkable organic material and a second ligand material encapsulated within the matrix material.

2. The light-emitting element according to claim 1, wherein the second ligand material is contained in the base material in a state that can be diffused into the light-emitting layer.

3. The light-emitting element according to claim 1 or 2, wherein the crosslinkable organic material does not contain amine groups, thiol groups, and halogens as terminal groups in its molecular structure, and the second ligand material contains sulfo groups, carboxyl groups, phosphate groups, or phosphine as terminal groups.

4. The light-emitting element according to any one of claims 1 to 3, wherein the first ligand material and the second ligand material are organic ligand materials having the same functional group.

5. The light-emitting element according to any one of claims 1 to 3, wherein the first ligand material and the second ligand material are the same inorganic ligand material.

6. The light-emitting element according to any one of claims 1 to 5, wherein the base material includes a photoresist.

7. The light-emitting element according to any one of claims 1 to 6, wherein the adjacent layer has a charge blocking function.

8. The adjacent layer is located between the light-emitting layer and the cathode, and the electrical conductivity of the adjacent layer is 1 × 10⁻⁶. －６ The light-emitting element according to claim 7, wherein the level is less than or equal to [S / m], and the highest occupied level of the adjacent layer is 0.1 [eV] or lower than the highest occupied level of the light-emitting layer.

9. The adjacent layer is located between the light-emitting layer and the anode, and the electrical conductivity of the adjacent layer is 1 × 10⁻⁶. －６ The light-emitting element according to claim 7, wherein the [S / m] is less than or equal to [S / m], and the lowest air level of the adjacent layer is 0.1 [eV] or higher than the lowest air level of the light-emitting layer.

10. The light-emitting element according to any one of claims 1 to 6, wherein the adjacent layer has a charge transport function.

11. The adjacent layer is located between the light-emitting layer and the cathode, and the electrical conductivity of the adjacent layer is 1 × 10⁻⁶. －６ The light-emitting element according to claim 10, wherein the value is greater than [S / m], and the lowest air level of the adjacent layer is 0.1 [eV] or higher than the lowest air level of the light-emitting layer.

12. The adjacent layer is located between the light-emitting layer and the anode, and the electrical conductivity of the adjacent layer is 1 × 10⁻⁶ －６ The light-emitting element according to claim 10, wherein the value is greater than [S / m], and the highest occupied level of the adjacent layer is 0.1 [eV] or more lower than the highest occupied level of the light-emitting layer.

13. The light-emitting element according to any one of claims 1 to 6, 10 to 12, wherein the thickness of the adjacent layer is 20 [nm] or less.

14. The light-emitting element according to any one of claims 1 to 13, wherein the adjacent layer is in contact with the upper surface and side surface of the light-emitting layer.

15. The light-emitting element according to any one of claims 1 to 13, wherein the adjacent layer is in contact with the upper and lower surfaces of the light-emitting layer.

16. The light-emitting element according to any one of claims 1 to 13, wherein the concentration of the second ligand material in the adjacent layer decreases in a direction away from the interface between the adjacent layer and the light-emitting layer.

17. The light-emitting element according to any one of claims 1 to 13, wherein the concentration of the first ligand material in the light-emitting layer decreases in a direction away from the interface between the light-emitting layer and the adjacent layer.

18. The light-emitting element according to any one of claims 1 to 13, wherein the concentration of the second ligand material in the adjacent layer increases in a direction away from the side surface of the adjacent layer.

19. The light-emitting element according to claim 18, wherein the side portion of the adjacent layer is deactivated.

20. The light-emitting element according to any one of claims 1 to 13, wherein the concentration of the first ligand material in the light-emitting layer increases in a direction away from the side surface of the light-emitting layer.

21. The light-emitting element according to claim 20, wherein the side portion of the light-emitting layer is deactivated.

22. The light-emitting element according to claim 5, wherein the base material includes a metal element that can form a salt with the second ligand material, and the metal element is also included in the quantum dot.

23. The light-emitting element according to any one of claims 1 to 22, wherein the light-emitting layer includes an inorganic medium located around the quantum dot.

24. The light-emitting element according to claim 23, wherein the inorganic medium comprises at least one selected from the group consisting of alkoxysilanes, polysilazanes, and polysiloxanes.

25. The light-emitting element according to any one of claims 1 to 24, wherein a recess is formed on the upper surface of the light-emitting layer, and the adjacent layer is in contact with the side surface of the recess.

26. The light-emitting element according to claim 25, wherein the recess penetrates the light-emitting layer.

27. A light-emitting device comprising: a first light-emitting element according to any one of claims 1 to 26, the first light-emitting element including a first light-emitting layer that emits a first color as the light-emitting layer; and a second light-emitting element according to any one of claims 1 to 26, the second light-emitting element including a second light-emitting layer that emits a second color as the light-emitting layer, wherein the first color and the second color are different primary colors.

28. The light-emitting device according to claim 27, wherein a portion of the first light-emitting layer overlaps with the second light-emitting layer.

29. The light-emitting device according to claim 27 or 28, wherein the second ligand of the first light-emitting element and the second ligand of the second light-emitting element are different.

30. The light-emitting device according to claim 27, further comprising a gap layer connected to the adjacent layer of the first light-emitting element and the adjacent layer of the second light-emitting element, and located in the gap between the first and second light-emitting layers.

31. The light-emitting apparatus according to claim 27, comprising a first charge transport layer located beneath the first light-emitting layer and a second charge transport layer located beneath the second light-emitting layer and separated from the first charge transport layer.

32. The light-emitting device according to claim 31, wherein the first and second charge transport layers are photocrosslinkable and their respective sides are deactivated.

33. A display device comprising the light-emitting device described in claim 27.

34. A method for manufacturing a light-emitting element, comprising the steps of: forming a light-emitting layer containing light-emitting quantum dots and a first ligand material capable of coordinating with the quantum dots; and forming an adjacent layer in contact with the light-emitting layer, containing a matrix material comprising a crosslinkable organic material and a second ligand material encapsulated within the matrix material.

35. A method for manufacturing a light-emitting element according to claim 34, comprising the step of forming the light-emitting layer by patterning a planar quantum dot layer containing the quantum dots and the first ligand material.

36. The method for manufacturing a light-emitting element according to claim 35, comprising forming the adjacent layer on the planar quantum dot layer by photolithography, and patterning the quantum dot layer using the adjacent layer as a mask.

37. A method for manufacturing a light-emitting element according to claim 36, comprising laminating a planar quantum dot layer on a planar underlayer having charge functionality, and then patterning the quantum dot layer and the underlayer together using the adjacent layer as a mask.

38. The method for manufacturing an luminescent element according to claim 37, wherein the underlying layer has photocrosslinking properties.

39. The method for manufacturing a light-emitting element according to claim 35, wherein the adjacent layer is formed after the light-emitting layer has been patterned.

40. The method for manufacturing a light-emitting element according to claim 35, wherein, after patterning the light-emitting layer, the concentration of the first ligand material on the side of the light-emitting layer is reduced by rinsing.

41. The method for manufacturing a light-emitting element according to claim 35, wherein, after patterning the light-emitting layer, a coating layer comprising a base material containing a crosslinkable organic material and a second ligand material encapsulated in the base material is formed to cover the upper and side surfaces of the light-emitting layer, and the coating layer is etched to form the adjacent layer and the gap layer connected to the adjacent layer.

42. The method for manufacturing a light-emitting element according to claim 41, wherein the gap layer is thicker than the adjacent layer and functions as a bank.

43. The method for manufacturing a light-emitting element according to claim 35, wherein the light-emitting layer comprises an inorganic medium located around the quantum dot and a precursor of the inorganic medium.

44. The method for manufacturing a light-emitting element according to claim 35, wherein the light-emitting layer has photocrosslinking properties.

45. The method for manufacturing a light-emitting element according to claim 35, wherein the light-emitting layer includes a photocrosslinkable organic medium located around the quantum dot.

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