Light-emitting device, display device and manufacturing method of light-emitting device

Abstract

The light-emitting device (40) disclosed herein comprises: a first electrode (E1); a first functional layer (F1) located above the first electrode (E1); a quantum dot layer (EM) located above the first functional layer (F1), comprising quantum dots (QD) and dielectric material (MX); and a second electrode (E2) located above the quantum dot layer (EM), wherein the quantum dot layer (EM) comprises: a first portion (P1) overlapping the first electrode (E1) in top view; and a second portion (P2) not overlapping the first electrode (E1) in top view, wherein the quantum dot occupancy is smaller than that of the first portion (P1).

Description

Technical Field

[0001] This disclosure relates to a light-emitting device, a display device, and a method for manufacturing a light-emitting device. Background Technology

[0002] Patent document 1 discloses an organic EL display device comprising a hole transport layer located between an anode and a light-emitting layer, wherein the peripheral portion is thinner than the central portion, and an electron blocking layer located between the hole transport layer and the light-emitting layer, wherein the peripheral portion is thicker than the central portion.

[0003] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2008-235468 Summary of the Invention The problem the invention aims to solve The aperture ratio in the light-emitting device needs to be increased.

[0004] Solution for solving the problem The light-emitting device disclosed herein includes: a first electrode; a first functional layer located above the first electrode; a quantum dot layer located above the first functional layer and comprising quantum dots and a dielectric material; and a second electrode located above the quantum dot layer, the quantum dot layer comprising a first portion and a second portion, the first portion overlapping the first electrode when viewed from above, the second portion not overlapping the first electrode when viewed from above and having a quantum dot occupancy rate less than the first portion, and the dielectric material being insulating.

[0005] The display device according to this disclosure is configured to include a light-emitting device according to this disclosure.

[0006] The method for manufacturing a light-emitting device disclosed herein includes: a step of forming a first electrode; a step of forming a first functional layer using a material having at least one of polymerizability and crosslinking properties, the first functional layer being located above the first electrode; a step of forming a quantum dot layer above the first functional layer by removing solvent from a coating liquid containing quantum dots and a dielectric material; and a step of forming a second electrode above the quantum dot layer, wherein the first functional layer and the quantum dot layer are respectively formed to include a portion that overlaps with the first electrode when viewed from above and a portion that does not overlap with the first electrode when viewed from above, and the dielectric material is insulating.

[0007] Invention Effects According to one aspect of this disclosure, the aperture ratio of the light-emitting device can be increased. Attached Figure Description

[0008] Figure 1This is a cross-sectional view showing an example of the configuration of a light-emitting device according to an embodiment of the present disclosure.

[0009] Figure 2 This is a cross-sectional view illustrating an example of a method for manufacturing a light-emitting device according to an embodiment of this disclosure.

[0010] Figure 3 This is an enlarged cross-sectional view showing an example of a method for manufacturing a light-emitting device according to an embodiment of this disclosure.

[0011] Figure 4 This is a cross-sectional view showing an example of the configuration of a light-emitting device according to one embodiment.

[0012] Figure 5 This is a top view showing an example of the configuration of a light-emitting device according to one embodiment.

[0013] Figure 6 This is a diagram showing a TEM image obtained by taking a cut surface of a display device according to an embodiment of the present invention at the location where multiple pixel electrodes are cut across.

[0014] Figure 7 An example of shrinkage deformation during resin molding is shown.

[0015] Figure 8 A table showing pixel density and pixel size.

[0016] Figure 9 This is a diagram showing the area of ​​a pixel electrode and the spacing between adjacent pixel electrodes.

[0017] Figure 10 This is a graph showing the relationship between the spacing of adjacent pixel electrodes and the aperture ratio of a 6-inch mobile terminal display panel at a resolution of 4K.

[0018] Figure 11 This is a graph showing the relationship between the spacing of adjacent pixel electrodes and the aperture ratio of a 6-inch mobile terminal display panel at a resolution of 4K. Detailed Implementation

[0019] [Implementation Method 1] Figure 1 This is a cross-sectional view illustrating an example of the configuration of a light-emitting device according to an embodiment of this disclosure. For example... Figure 1As shown, the light-emitting device 40 of the present invention includes: a first electrode E1; a first functional layer F1 located above the first electrode E1; a quantum dot layer EM located above the first functional layer F1, including quantum dots QD and a dielectric material MX; and a second electrode E2 located above the quantum dot layer EM. The quantum dot layer EM includes: a first portion P1, which overlaps with the first electrode E1 when viewed from above; and a second portion P2, which does not overlap with the first electrode E1 when viewed from above, wherein the quantum dot occupancy rate of the second portion P2 is less than that of the first portion P1. The dielectric material MX is insulating.

[0020] Based on the above configuration, the quantum dot layer EM comprises quantum dots (QDs) and a dielectric material (MX). Compared to the first portion P1, the quantum dot occupancy rate of the second portion P2 is lower. Therefore, the luminous efficiency of the second portion P2 is lower than that of the first portion P1. The second portion P2 can reduce abnormal luminescence caused by abnormal current flowing between the edge EF of the first electrode E1 and the second electrode E2.

[0021] Therefore, the edge shield covering the edge EF of the first electrode E1 can be eliminated. Compared with the existing configuration that uses an edge shield to reduce abnormal light emission, according to the above configuration of this disclosure, the effective area of ​​the first electrode E1 can be increased by the amount without the edge shield, and the aperture ratio of the light-emitting device 40 can be improved.

[0022] In this disclosure, a quantum dot refers to a dot with a maximum width of 100 nm or less. The shape of the quantum dot is not particularly limited as long as it meets the aforementioned maximum width range, and is not limited to a sphere (with a circular cross-section). For example, it can be a polygonal cross-sectional shape, a rod-shaped three-dimensional shape, a dendritic three-dimensional shape, a three-dimensional shape with uneven surfaces, or a combination of these shapes. In this embodiment, the quantum dot is, for example, a semiconductor particle with a particle size of 100 nm or less, and can be a crystal of group II-VI semiconductor compounds such as MgS, MgSe, MgTe, CaS, CaSe, CaTe, SrS, SrSe, SrTe, BaS, BaSe, BaTe, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, HgTe, and / or a crystal of group III-V semiconductor compounds such as GaAs, GaP, InN, InAs, InP, InSb, and / or a crystal of group IV semiconductor compounds such as Si, Ge. Alternatively, quantum dots can also have a core / shell structure, where the aforementioned semiconductor crystal serves as the core, and the core is coated with a shell material with a wide band gap. Furthermore, the shell does not necessarily completely cover the core; it can also be formed within a portion of the core.

[0023] The second portion P2 of the quantum dot layer EM can have a larger dielectric material occupancy rate compared to the first portion P1. Since the dielectric material MX is insulating, a higher dielectric material occupancy rate results in lower conductivity. Therefore, the lower conductivity of the second portion P2 compared to the first portion P1 reduces abnormal current flowing between the edge EF of the first electrode E1 and the second electrode E2. Furthermore, by reducing abnormal current, abnormal luminescence caused by abnormal current can be further reduced. In particular, the second portion P2 is preferably insulating. A conductivity of 10 per unit volume can be achieved. -8 Below [A / (V·m)], or with a resistivity of 10 Ω per unit volume 8 Materials and structural elements with a strength of [Ω·m] or higher are called insulating materials.

[0024] In this invention, "dielectric material occupancy" is the area ratio of dielectric material MX in the cross-section of quantum dot layer EM. "Quantum dot occupancy" is the area ratio of quantum dot QD in the cross-section of quantum dot layer EM.

[0025] For example, energy-dispersive X-ray analysis (EDX) is performed on the cross-section obtained by cutting the quantum dot layer EM across the luminescent region to obtain a composition map. In the composition map, the total area of ​​the regions containing only quantum dots (QDs) is the area occupied by the quantum dots (QDs) in that cross-section, and the total area of ​​the regions containing only dielectric material (MX) is the area occupied by the dielectric material (MX) in that cross-section. Furthermore, the sum of the areas occupied by the quantum dots (QDs) and the dielectric material (MX) is the area of ​​the quantum dot layer EM. Within the cross-section that includes the first part P1 but does not include the second part P2, the areas occupied by the quantum dots (QDs) and the dielectric material (MX) are calculated, and based on this, the dielectric material occupancy and quantum dot occupancy in the first part P1 can be obtained. Similarly, the occupancy rates in the second part P2 can also be obtained.

[0026] For example, based on EDX, TEM images taken using a transmission electron microscope (TEM) on the same cross-section can also be obtained. The brightness of the region corresponding to the detection of elements contained only in the quantum dot (QD) and the brightness of the region corresponding to the detection of elements contained only in the dielectric material (MX) can be determined using the control group image and the TEM image, respectively. Furthermore, the corresponding brightness can be set as the area occupied by the quantum dot (QD) and the dielectric material (MX) based on the total area occupied by the TEM image.

[0027] The first functional layer F1 may be composed of a material having at least one of polymerizability and crosslinking properties. This material may have a thickness direction resulting from at least one of the aforementioned polymerizability and crosslinking properties. Figure 1 The shrinkage property (in the vertical direction) can also have a direction orthogonal to the thickness direction (in the vertical direction). Figure 1The shrinkage (in the left and right directions) of polymeric materials. Polymeric materials shrink and solidify simultaneously during polymerization. Crosslinked materials shrink and solidify simultaneously during crosslinking. Therefore, the first functional layer F1 can naturally shrink and deform along with polymerization and / or crosslinking.

[0028] For example, the first functional layer F1 may contain at least one of TFB, PVK, and TPD. TFB, PVK, and TPD are materials with polymerizability and hole transport properties, and TFB also has crosslinking properties. Alternatively, the first functional layer F1 may also contain materials with hole transport properties such as photoresist and nickel oxide (NiO). The first functional layer F1 may also contain materials with electron transport properties such as photoresist and zinc oxide (ZnO). The photoresist has at least one of polymerizability and crosslinking properties.

[0029] The light-emitting device 40 may include a third electrode E3 located on the same layer as the first electrode E1, and a second portion P2 of the quantum dot layer EM located on the gap GP between the first electrode E1 and the third electrode E3. This allows for the separation of light emission caused by the voltage or current applied to the first electrode E1 from light emission caused by the voltage or current applied to the third electrode E3 (so-called "pixel separation"). The first portion P1 of the quantum dot layer EM may emit light, while the second portion P2 may not. In this case, the light-emitting device 40 may include a first light-emitting element 10 and a second light-emitting element 20. The first light-emitting element 10 includes the first electrode E1, the first portion P1 of the quantum dot layer EM, and the portion of the second electrode E2 overlapping with the first electrode E1. The second light-emitting element 20 includes the third electrode E3. The second light-emitting element 20 may have a configuration substantially the same as the first light-emitting element 10, or it may have a different configuration. The second light-emitting element 20 may emit light of the same color as the first light-emitting element 10, or it may emit light of a different color.

[0030] The pixel electrodes, such as the first electrode E1 and the third electrode E3, have a higher formation precision than the edge mask. Since the pixel electrodes are formed at the very beginning of the manufacturing process of the light-emitting device 40, there are fewer restrictions on photolithography, allowing for high-precision linewidth reduction and easy formation of fine lines. Furthermore, the width of the gap GP is simply limited by the photolithographic resolution on the plane. Therefore, compared to a structure with an edge mask, the structure according to this disclosure reduces the width of the gap GP by a corresponding amount, thereby increasing the area ratio of the first electrode E1 and improving the aperture ratio of the light-emitting device 40.

[0031] In the first functional layer F1, the thickness of the portion Q2 below the second part P2 can also be more than 1.5 times the thickness of the portion Q1 below the first part P1. The first electrode E1 can be flat.

[0032] When viewed from above, the second electrode E2 can overlap with the first electrode E1 and the third electrode E3, as well as with the gap GP. The second electrode E2 can be a common electrode that extends throughout the first light-emitting element 10 and the second light-emitting element 20. Furthermore, when viewed from above, the first functional layer F1 can overlap with the first electrode E1 and the third electrode E3, as well as with the gap GP.

[0033] When viewed from above, the second electrode E2 overlaps with the second portion P2 and may have a downwardly protruding curved portion VX. The upper surface of the first functional layer F1, when viewed from above, overlaps with the second portion P2 and may have a downwardly protruding recess CX. The curved portion VX may correspond one-to-one with the recess CX. The curved portion VX may overlap with the peripheral portion PA of the first electrode E1 when viewed from above.

[0034] The correspondence between the curved portion VX and the recessed portion CX can be confirmed by observing a cross-section of the light-emitting element 10. Preferably, this is confirmed by observing a cross-section that cuts through the light-emitting region of the light-emitting element 10 along the thickness direction of the second electrode E2, and more preferably by observing a cross-section that cuts through the middle of the light-emitting region. The recessed portion CX overlaps with the corresponding curved portion VX when viewed from above. When the thickness of each layer from the first functional layer F1 to the second electrode E2 is about tens of nm or less, the radius of curvature of the recessed portion CX is approximately equal to or close to the radius of curvature of the corresponding curved portion VX.

[0035] The first functional layer F1 and the quantum dot layer EM can be in contact. Through direct contact, deformation of the first functional layer F1 can easily affect the quantum dot layer EM and the layers above it.

[0036] The dielectric material MX can be a powder. The powder may, for example, contain silicon oxide, silicon nitride, aluminum oxide, or zirconium. In this invention, "powder" refers to a group of particles with a particle size smaller than the quantum dot QDs contained in the quantum dot layer EM. In the nanoscale world, larger particles are less affected by surface friction and move more easily. Therefore, within the quantum dot layer EM, the quantum dot QDs can move more easily than the dielectric material MX.

[0037] Alternatively, the dielectric material MX can be a porous body. The quantum dot layer EM or the light-emitting layer EM can also contain powder and porous bodies. Because porous bodies have a low average density and are brittle, they can be easily transformed into a powder state.

[0038] The dielectric material MX can be a glassy material or a wide-gap material with a wide band gap between the valence band and the conduction band. Wide-gap materials include, for example, metal oxides, group IV oxides, group II oxides, group I halides, group III nitrides, and group IV-IV compounds. In this disclosure, the group designations using Roman numerals are based on the old IUPAC (International Union of Pure and Applied Chemistry) or old CAS (Chemical Abstracts Service) system, while the group designations using Arabic numerals are based on the new IUPAC system.

[0039] The light-emitting device 40 may include a second functional layer F2 located between the quantum dot layer EM and the second electrode E2. The second functional layer F2 may contain multiple nanoparticles ND. When viewed from above, the second functional layer F2 overlaps with the second portion P2, and may also have a downwardly protruding curved portion WX. The curved portion WX may correspond one-to-one with the recessed portion CX. The curved portion WX may also be expanded to overlap with the peripheral portion PA of the first electrode E1 when viewed from above. The light-emitting device 40 may include a third functional layer F3 located between the first electrode E1 and the first functional layer F1. The third functional layer F3 may be formed with a substantially uniform thickness. The thickness of the first electrode E1 may be at least 1.5 times the thickness of the third functional layer F3, or at least 1.5 times the thickness of the portion of the third functional layer F3 that overlaps with the first electrode E1 when viewed from above.

[0040] The correspondence between the curved portion WX and the recessed portion CX can be confirmed by observing the cross-section of the light-emitting element 10, given the correspondence between the curved portion VX and the recessed portion CX. When the thicknesses of the first functional layer F1, the light-emitting layer EM, the second functional layer F2, and the second electrode E2 are all around tens of nm or less, the radius of curvature of the corresponding curved portion WX is approximately equal to or close to that of the curved portion WX.

[0041] Multiple cracks CR can be formed at the second electrode E2. These multiple cracks CR can be formed at the bend VX or outside the bend VX.

[0042] The first functional layer F1 can be either a hole transport layer or an electron transport layer. For example, when the first electrode E1 is the anode, the third functional layer F3 is the hole injection layer, the first functional layer F1 is the hole transport layer, the second functional layer F2 is the electron transport layer, and the second electrode E2 is the cathode. Alternatively, when the first electrode E1 is the cathode, the third functional layer F3 is the electron injection layer, the first functional layer F1 is the electron transport layer, the second functional layer F2 is the hole transport layer, and the second electrode E2 is the anode.

[0043] The light-emitting device 40 may have a second electrode E2 that is a light-reflective, bottom-emitting structure. The second electrode E2 may, for example, contain silver or aluminum. In this case, the first electrode E1 may also be light-transmitting.

[0044] Alternatively, the light-emitting device 40 may have a top-emitting structure where the second electrode E2 is transparent. The second electrode E2 may, for example, comprise a transparent metal oxide such as indium tin oxide, indium zinc oxide, or indium gallium zinc oxide, or it may be a metal film with a thickness of 30 Å or less. In this case, the first electrode E1 may be light-reflective.

[0045] The light-emitting device 40 may include a thin-film sealing layer TFE covering the first light-emitting element 10 and the second light-emitting element 20. The thin-film sealing layer TFE may sequentially include, for example, an inorganic sealing film 11, an organic sealing film 12, and an inorganic sealing film 13.

[0046] (Manufacturing method) Figure 2 This is a cross-sectional view illustrating an example of a method for manufacturing a light-emitting device according to an embodiment of this disclosure. For example... Figure 2 As shown, in the manufacturing method of the light-emitting device according to the present invention, a first electrode E1 is formed (step S10). In step S10, for example, a wiring pattern mask is formed on a substrate SB using photolithography, and a conductive material is deposited thereon using sputtering or vacuum evaporation. Then, by removing the wiring pattern mask, the conductive material film is patterned to obtain the first electrode E1. In step S10, either a third electrode E3 or other pixel electrodes can be formed.

[0047] Next, a first functional layer F1 is formed on a layer above the first electrode E1 using a material having at least one of polymerizability and crosslinking properties (step S30). In step S30, the first functional layer F1 can be formed using materials such as TFB, PVK, and TPD, which have at least one of polymerizability and crosslinking properties as well as charge transport properties. Alternatively, the first functional layer F1 can be formed using materials such as photoresist, which have at least one of polymerizability and crosslinking properties, and materials such as nickel oxide and zinc oxide, which have charge transport properties. A third functional layer F3 can be formed between steps S10 and S30 (step S20).

[0048] In step S30, using materials such as TFB, which possess both polymerizability and crosslinking properties, is beneficial for improving the reliability of the light-emitting element 10. By crosslinking the polymers with each other, the stability of the first functional layer F1 is improved, and the durability of the light-emitting element 10 is enhanced.

[0049] Before the formation of the quantum dot layer EM, the upper surface of the first functional layer F1 is generally flat. At this time, the first functional layer F1 is cured to the extent that the coating liquid PL (described later) can be coated onto the first functional layer F1. Inside the first functional layer F1, polymerization and / or crosslinking are in progress or can be repeated.

[0050] Next, a coating solution PL containing multiple quantum dots (QDs), dielectric material (MX), and solvent is coated onto the first functional layer F1 (step S42). The solvent is then removed from the coating solution PL (step S44), thereby forming the quantum dot layer EM (step S40). Next, a second electrode E2 is formed on top of the quantum dot layer EM (step S60). The second functional layer F2 can be formed between steps S40 and S60 (step S50). A thin film sealing layer TFE covering the second electrode E2 can be formed after step S60 (step S70).

[0051] The first functional layer F1 and the quantum dot layer EM are respectively formed to include portions Q1 and P1 that overlap with the first electrode E1 when viewed from above, and portions Q2 and P2 that do not overlap with the first electrode E1 when viewed from above. In addition, the dielectric material M is insulating.

[0052] Figure 3 This is an enlarged cross-sectional view illustrating an example of a method for manufacturing a light-emitting device according to an embodiment of the present invention. For the sake of simplicity, Figure 3 The substrate SB and the thin-film sealing layer TFE are omitted. For example... Figure 3 As shown, after the quantum dot layer EM is formed, at least one of polymerization and crosslinking is performed in the first functional layer F1 (step S80). The first functional layer F1 can be expanded in the thickness direction by at least one of polymerization and crosslinking. Figure 3 It can shrink in the vertical direction, or in a direction orthogonal to the thickness direction. Figure 3 The contraction occurs in the left-right direction. Since the first functional layer F1 is fixed to the layer directly below it, the contraction force of the first functional layer F1 acts isotropically in a plane orthogonal to the thickness direction. The lower surface of the first functional layer F1 is in contact with the layer directly below it, and the deformation and contraction are restricted by the layer directly below it. Compared with the lower surface, the upper surface of the first functional layer F1 is more prone to deformation and contraction. As a result, a difference in the amount of contraction between the upper and lower surfaces of the first functional layer F1 occurs, and the upper surface deforms to form a group of recesses CG. Step S80 can be performed after the second functional layer F2 and the second electrode E2 have been formed.

[0053] Polymerization and crosslinking can be accelerated by heat or light. From the viewpoint of preventing cracking, it is preferable to avoid maintaining temperatures higher than room temperature between steps S80, and preferably to avoid sunlight or short-wavelength electromagnetic waves below near-ultraviolet light. The reaction rates of polymerization and / or crosslinking vary depending on the material of the first functional layer F1. It is preferable to ensure the duration of step S80 sufficiently according to the reaction rate; for example, the light-emitting device 40 may be left to stand for several hours or days.

[0054] In step S80, the shrinkage of the portion Q2 that does not overlap with the first electrode E1 in the first functional layer F1 is greater than the shrinkage of the portion Q1. Therefore, a recess CX is formed on the upper surface of the first functional layer F1. Then, through the formation of the recess CX, the quantum dot layer EM, the second functional layer F2, and the second electrode E2 are deformed to form curved portions VX and WX.

[0055] In step S80, a portion or all of the porous body can undergo a state change to powder. For example, if a porous body of dielectric material MX is formed around the quantum dot QD in step S40, the force that moves the quantum dot QD in step S80 acts on the light-emitting layer EM. As a result, the porous body easily transforms into a powder state, and the quantum dot QD moves. Assuming that the dielectric material MX is in a non-porous, dense state, it is presumed that the quantum dot is difficult to move. Therefore, the dielectric material MX in the light-emitting layer EM can contain at least one of powder and porous body. In the light-emitting layer EM, for example, the region VA overlapping with the curved portions V1, V2, V3 can contain powder of dielectric material MX, and the region FA overlapping with the flat portion FP can contain porous body of dielectric material MX.

[0056] [Implementation Method 2] Figure 4 This is a cross-sectional view illustrating an example of the configuration of a light-emitting device according to an embodiment of this disclosure. For example... Figure 4 As shown, the light-emitting device 40 may also have an insulating dam structure BK between the first electrode E1 and the third electrode E3. In this case, the dam structure BK may not cover the edge EF of the first electrode E1. The dam structure BK may surround the first electrode E1 and may contain a resin material such as polyimide. The dam structure BK may be formed after the first electrode E1.

[0057] [Implementation Method 3] Figure 5 This is a top view illustrating an example of the configuration of a display device according to an embodiment of this disclosure. Figure 5As shown, the display device 100 disclosed herein includes the light-emitting device 40 disclosed herein. For example, the display device 100 may have: a display area DA, which is provided with a plurality of sub-pixels PX; and a border area NA, which is provided with a driving circuit DC for driving the display area DA, one of the plurality of sub-pixels PX including a first light-emitting element 10 and a pixel circuit 30, the other of the plurality of sub-pixels PX including a second light-emitting element 20 and a pixel circuit 30, and the display area DA including the light-emitting device 40.

[0058] (Example 1) A display device according to an embodiment of the present disclosure is fabricated. In this embodiment, the first light-emitting element 10 and the second light-emitting element 20 included in the light-emitting device 40 are in a forward orientation. The first electrode E1 and the third electrode E3 are anodes, the third functional layer F3 is a hole injection layer, the first functional layer F1 is a hole transport layer, the second functional layer F2 is an electron transport layer, and the second electrode E2 is a cathode. The light-emitting device 40 does not have a dam structure.

[0059] First, a thin-film transistor (TFT) substrate, SB, is prepared, and an indium tin oxide (ITO) wiring layer is formed on the substrate SB. The ITO wiring layer includes a first electrode E1. Next, a hole injection layer containing nickel oxide (NiO) is formed. Nickel oxide can be formed by coating, inkjet printing, or vacuum evaporation of a nanoparticle-dispersed colloidal solution. Any of these methods—coating, printing, and evaporation—can produce a nickel oxide film of approximately uniform thickness across the entire panel surface.

[0060] Next, as the first functional layer F1, a cross-linked TFB film is formed by coating or printing. During coating or printing, the cross-linked TFB is fluid, filling the unevenness formed by the ITO wiring layer, and the upper surface is generally flat. Then, the cross-linked TFB is slightly cured by coating liquid PL onto the first functional layer F1. Therefore, the thickness of the first functional layer F1 is distributed according to the ITO wiring layer. Compared to the thickness of the first portion P1 in the first functional layer that does not overlap with the first electrode E1, the thickness of the second portion P2 that does not overlap with the first electrode E1 is increased by an amount corresponding to the thickness of the first electrode E1.

[0061] Next, the coating solution PL, prepared as described later, is applied to the panel. Then, the panel is heated to 130°C for approximately 15 minutes, maintained at 130°C for approximately 10 minutes, and cooled to room temperature for approximately 15 minutes. This removes the solvent, forming the quantum dot layer EM. Rapid cooling during this process can sometimes induce tensile stress on the surface of the quantum dot layer EM, leading to cracking. Therefore, slow cooling is preferred.

[0062] Next, a second functional layer F2 and a second electrode E2 are formed, and the second electrode E2 is sealed with a thin-film sealing layer TFE. Afterward, the first functional layer F1 is crosslinked and polymerized in the display device 100, which has been left to stand at room temperature for at least about 5 hours.

[0063] In the preparation of the coating solution PL, firstly, it is prepared in octane (C8H2O) 18 The system comprises a first liquid L1 containing quantum dots (QDs) and a second liquid L2 containing zinc chloride (ZnCl2), 3-(mercaptopropyl)trimethoxysilane (MPS), and tetramethyl orthosilicate (TMOS) dissolved in N-methylformamide (NMF). The quantum dots (QDs) are commercially available quantum dots with a core of ZeSeTe and a shell of ZeS. The concentrations in the second liquid L2 are 0.2 mol / L for ZnCl2, 0.2 mol / L for MPS, and 0.02 mol / L for TMOS. The following chemical formula (1) represents MPS and chemical formula (2) represents TMOS.

[0064] [Chemistry 1] [Chemistry 2] The first and second liquids were thoroughly stirred and mixed. Through stirring, the organic ligands initially coordinated to the quantum dot (QD) detached, and the thiol groups of MPS took their place. Accompanying this ligand exchange, the QD transferred from the first liquid to the second liquid. Additionally, in the second liquid, the trimethoxysilyl group of MPS reacted with TMOS to synthesize silicon oxide. Silicon oxide is the dielectric material MX used in this embodiment.

[0065] Next, by removing the first liquid and adding ethyl acetate to the second liquid, multiple quantum dots (QDs) protected by the medium material MX were precipitated and separated. Then, after multiple alcohol dehydration processes, the mixture was dispersed in a solvent to obtain a coating solution PL containing multiple quantum dots (QDs) protected by the medium material MX and the solvent.

[0066] Figure 6 This is a diagram illustrating a TEM image obtained by using a transmission electron microscope (TEM) to capture a cut surface obtained by slicing the display device according to an embodiment of this disclosure along the thickness direction of the second electrode E2 at the location where multiple pixel electrodes are transversely cut. (See diagram for reference.) Figure 6 As shown, in each light-emitting element, the upper surface of the second electrode E2 is deformed in a concave manner, that is, a curved portion is formed in the second electrode E2. The deformation of the second electrode E2 is large directly above the localized thickening position of the first functional layer F1. Within the first functional layer F1, the position between the first electrode E1 and the third electrode E3 is locally thicker when viewed from above, compared to the position overlapping with the first electrode E1 when viewed from above.

[0067] The first functional layer F1 is cured immediately after formation to allow for the application of coating liquid PL, but polymerization and crosslinking are not yet complete after formation. Polymerization and crosslinking continue during and after the formation of the quantum dot layer EM, causing the first functional layer F1 to shrink. This results in compressive stress at the interface between the first functional layer F1 and the quantum dot layer EM, and tensile stress on the opposite surface of the quantum dot layer EM. Due to the tensile stress, a force presses the opposite surface of the quantum dot layer EM against the first functional layer F1. The inventors hypothesize that the thicker the first functional layer F1, the greater the compressive and tensile stresses will be. Therefore, as described above, a bend is formed between the first electrode E1 and the third electrode E3 at the second electrode E2.

[0068] Furthermore, the quantum dot occupancy of the second portion P2, which does not overlap with the first electrode E1, is smaller than that of the first portion P1, which overlaps with the first electrode E1, in the quantum dot layer EM. Specifically, the quantum dot occupancy per unit area of ​​the cross-section is 1.4% in the first portion P1 and 74.6% in the second portion P2.

[0069] Refer again Figure 3 It is known that when the quantum dot layer EM deforms due to compressive and tensile stress in step S80, the quantum dots QD move from the second part P2 to the first part P1 within the quantum dot layer EM. On the other hand, if the dielectric material MX is compared with the quantum dots QD, the inventors speculate that there is no relative movement. The result of such different movements is that the quantum dots QD are swept out from the bends, while the dielectric material MX remains in each bend. Therefore, it is inferred that the dielectric material MX is a powder, a porous material, or a mixture thereof. The quantum dots QD are protected by the dielectric material MX and can move within the quantum dot layer EM under stress. Through the movement of the quantum dots QD, it is inferred that a density of quantum dots QD is generated within the quantum dot layer EM. By generating this density throughout the display device 100, it is inferred that the bends observed in the TEM image appear.

[0070] If we observe further... Figure 6 The TEM images show that the density of the crack CR in the curved portion of the second electrode E2 is greater than that in the flat portion. It is speculated that this is because the second electrode E2 could not withstand the stretching during deformation of the quantum dot layer EM, leading to its fracture. The crack CR in the second electrode E2 extends through the entire electrode.

[0071] To generate such a deformation of the quantum dot layer EM, it is required that the quantum dots (QDs) can move within the quantum dot layer EM when the first functional layer F1 contracts. Specifically, the dielectric material MX needs to be weakly coupled to or not coupled to the quantum dots (QDs). For example, the shell of the quantum dots (QDs) can be a II-VI compound such as zinc sulfide, and the dielectric material MX can be a stable compound such as silicon oxide or aluminum oxide, with a different crystal system than the shell, capable of becoming a porous body or powder. Materials with different crystal systems will not bond with each other. In addition, materials that can be synthesized above room temperature and below approximately 150°C, when synthesized under conditions without crystal nuclei and without drastic temperature changes, will become porous bodies or powders.

[0072] Figure 7 This illustrates an example of shrinkage deformation during resin molding. It is known that the shrinkage of general cross-linked or polymeric materials is determined by localized volume. For example... Figure 7 As shown, for example, in the injection molding of resin parts, it is known that the large volume areas shrink and deform due to the reinforcing ribs RB. This shrinkage deformation also occurs in light-emitting elements, light-emitting devices, and display devices that use cross-linked or polymeric materials in the first functional layer F1. By controlling the thickness distribution of the first functional layer F1, the location of the shrinkage deformation of the first functional layer F1 can be controlled, and the deformation of the quantum dot layer EM and the sweeping out of quantum dots QD can be induced and controlled.

[0073] In this embodiment, as described above, the thickness of the first functional layer F1 is distributed according to the ITO wiring layer. Therefore, the inventors speculate that pixel separation is achieved in the light-emitting device 40 or the display device 100 by utilizing the shrinkage deformation of the first functional layer F1. The thickness distribution of the first functional layer F1 can also be controlled by other methods.

[0074] Figure 8 A table showing pixel density and pixel size. (e.g.) Figure 8 As shown, the pixel density and pixel area are calculated based on the diagonal size and resolution of the display area DA of the display device 100.

[0075] Figure 9 This is a diagram showing the area of ​​a pixel electrode and the spacing between adjacent pixel electrodes. (Example) Figure 9 As shown, for simplification, in a top-down view, it is assumed that each pixel electrode is square and the spacing between adjacent pixel electrodes is uniform. The area of ​​the pixel electrode is set as S, and the spacing between adjacent pixel electrodes is set as d. At this time, the pixel area of ​​each pixel is represented by equation (1), and the aperture ratio is represented by equation (2).

[0076] [Mathematical Expression 1] Pixel area of ​​each pixel: [Mathematical Expression 2] Slot ratio Figure 10 It is a graph showing the relationship between the spacing of adjacent pixel electrodes and the aperture ratio of a 6-inch mobile terminal display panel with a resolution of 4K. Figure 11 This is a graph showing the relationship between the spacing of adjacent pixel electrodes and the aperture ratio in the case of a large 60-inch display panel with a resolution of 4K. The relationship between the spacing of adjacent pixel electrodes and the aperture ratio is calculated according to equations (1) and (2) above. In addition, the pixel area is expressed by equation (3), and the pixel area is a fixed value when the size of the display panel is fixed. Figure 10 as well as Figure 11 As shown, the smaller the size of the display panel, the smaller the pixel area, so the reduction in pixel spacing leads to a more significant increase in aperture ratio. Furthermore, the higher the resolution, the smaller the pixel area; therefore, similarly, it can be expected that the reduction in pixel spacing will result in a more significant increase in aperture ratio.

[0077] [Mathematical Formula 3] Pixel Area In this embodiment, by eliminating the edge shield, the spacing between the first electrode E1 and the third electrode E3 can be reduced from 5 μm to 1 μm. Therefore, in the case of a 6-inch panel, the aperture ratio can be increased from 50% to 87%, and in the case of a 60-inch panel, the aperture ratio can be increased from 93% to 98%.

[0078] (Example 2) Fabrication of a display device according to an embodiment of the present disclosure. The light-emitting device 40 of this embodiment 2 has a dam structure BK. Nickel oxide of substantially uniform thickness can be integrally formed on the panel surface containing the dam structure BK by any method of coating, printing, or vapor deposition.

[0079] This disclosure is not limited to the embodiments described above, and various modifications can be made within the scope of the claims. Embodiments obtained by appropriately combining the technical solutions 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 methods disclosed in each embodiment.

[0080] Explanation of reference numerals in the attached figures 40 Light-emitting device 100 display devices BK Dike Structure CR cracks E1 First Electrode E2 Second Electrode E3 Third Electrode EM quantum dot layer F1 First Functional Layer F2 Second Functional Layer F3 Third Functional Layer GP gap PL coating liquid ND nanoparticles MX dielectric material P1 Part 1 Part 2, Page 2 QD quantum dots VX and WX bends.

Claims

1. A light-emitting device, characterized in that, include: A first electrode; a first functional layer located above the first electrode; a quantum dot layer located above the first functional layer and comprising quantum dots and a dielectric material; and a second electrode located above the quantum dot layer, the quantum dot layer comprising a first portion and a second portion, the first portion overlapping the first electrode in a top view, and the second portion not overlapping the first electrode in a top view and having a quantum dot occupancy rate less than that of the first portion. The dielectric material is insulating.

2. The light-emitting device according to claim 1, characterized in that, The occupancy rate of the dielectric material in the second part is greater than that in the first part.

3. The light-emitting device according to claim 2, characterized in that, The second part is insulating.

4. The light-emitting device according to any one of claims 1 to 3, characterized in that, The first functional layer is composed of a material having at least one of polymerizability and crosslinking properties.

5. The light-emitting device according to any one of claims 1 to 4, characterized in that, It has a third electrode located in the same layer as the first electrode, and the second part is located in the gap between the first electrode and the third electrode.

6. The light-emitting device according to any one of claims 1 to 5, characterized in that, The first part emits light, while the second part does not.

7. The light-emitting device according to any one of claims 1 to 6, characterized in that, The thickness below the second part of the first functional layer is more than 1.5 times the thickness below the first part.

8. The light-emitting device according to claim 5, characterized in that, The second electrode overlaps with the first electrode and the third electrode when viewed from above.

9. The light-emitting device according to claim 8, characterized in that, The first functional layer overlaps with the first electrode and the third electrode when viewed from above.

10. The light-emitting device according to claim 5, characterized in that, There is no insulating dam structure between the first electrode and the third electrode.

11. The light-emitting device according to claim 5, characterized in that, An insulating dam structure exists between the first electrode and the third electrode.

12. The light-emitting device according to any one of claims 1 to 11, characterized in that, The second electrode overlaps with the second part when viewed from above, and the second electrode has a downwardly protruding curved portion.

13. The light-emitting device according to any one of claims 1 to 12, characterized in that, The first functional layer and the quantum dot layer are connected.

14. The light-emitting device according to any one of claims 1 to 13, characterized in that, The medium material is a powder.

15. The light-emitting device according to any one of claims 1 to 13, characterized in that, The medium material is a porous material.

16. The light-emitting device according to any one of claims 1 to 13, characterized in that, The medium material comprises powder and porous material.

17. The light-emitting device according to any one of claims 1 to 16, characterized in that, It also includes a second functional layer, which is located between the quantum dot layer and the second electrode, and the second functional layer contains multiple nanoparticles.

18. The light-emitting device according to any one of claims 1 to 17, characterized in that, It also includes a third functional layer, which is located between the first electrode and the first functional layer. The thickness of the first electrode is more than 1.5 times the thickness of the third functional layer.

19. The light-emitting device according to any one of claims 1 to 18, characterized in that, Multiple cracks were formed on the second electrode.

20. The light-emitting device according to claim 4, characterized in that, The first functional layer includes at least one of TFB, PVK and TPD.

21. The light-emitting device according to claim 14 or 16, characterized in that, The powder contains silicon oxide, silicon nitride, aluminum oxide, or zirconium.

22. The light-emitting device according to any one of claims 1 to 21, characterized in that, The first functional layer is a hole transport layer or an electron transport layer.

23. The light-emitting device according to any one of claims 1 to 22, characterized in that, The first electrode is the anode.

24. A display device, characterized in that, It includes the light-emitting device according to any one of claims 1 to 23.

25. A method for manufacturing a light-emitting device, characterized in that, include: The process of forming the first electrode; The process of forming a first functional layer using a material having at least one of polymerizability and crosslinkability, wherein the first functional layer is located above the first electrode; Above the first functional layer, a process of forming a quantum dot layer by removing solvent from a coating liquid containing quantum dots and a dielectric material; and In the process of forming a second electrode on top of the quantum dot layer, The first functional layer and the quantum dot layer are respectively formed to include a portion that overlaps with the first electrode when viewed from above and a portion that does not overlap with the first electrode when viewed from above. The dielectric material is insulating.

26. The method for manufacturing a light-emitting device according to claim 25, characterized in that, The medium material comprises at least one of powder and porous material.

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