Electroluminescent device, manufacturing method, display panel and display device

Abstract

The present invention discloses an electroluminescent device, a manufacturing method, a display panel and a display device. The electroluminescent device includes a stacked electron transport layer, a perovskite quantum dot light-emitting layer and a hole transport layer. The perovskite quantum dot light-emitting layer is located between the electron transport layer and the hole transport layer, and the hole transport layer includes a crosslinking agent crosslinked with the hole transport layer material. By using the crosslinking of the crosslinking agent and the hole transport layer, the hole transport layer can not only collect and transport holes, but also be used as a mask during the patterning process of the perovskite quantum dot light-emitting layer, avoiding the residue generated on the perovskite quantum dot light-emitting layer when a photoresist is used as a mask, and capable of improving the injection efficiency of carriers and the display effect.

Description

Technical Field

[0001] The present application relates to the field of display technologies, and particularly to an electroluminescent device, a manufacturing method, a display panel, and a display device. Background Art

[0002] A light-emitting diode (LED) emits light by the recombination of electrons and holes, and has been widely used in the display field. Quantum dots, due to their narrow emission spectra, adjustable emission wavelengths by size, and high luminous efficiency, make QLEDs (Quantum Dot Light Emitting Diodes) powerful competitors in new display technologies.

[0003] Currently, a photoresist is often used as a mask in patterning the quantum dot light-emitting layer of QLEDs. However, in an electroluminescent scenario, due to the residual insulating photoresist on the surface of the quantum dot light-emitting layer, it is difficult for holes or electrons to be injected into the quantum dot light-emitting layer, affecting the display effect of QLEDs. Summary of the Invention

[0004] In view of the above problems, the present invention provides an electroluminescent device, a manufacturing method, a display panel, and a display device, which can improve the efficiency of hole or electron injection into the light-emitting layer and is beneficial to improving the display effect.

[0005] In a first aspect, the present application provides the following technical solutions through an embodiment:

[0006] An electroluminescent device, the electroluminescent device includes a stacked electron transport layer, a perovskite quantum dot light-emitting layer, and a hole transport layer; the perovskite quantum dot light-emitting layer is located between the electron transport layer and the hole transport layer, and the hole transport layer includes a crosslinking agent crosslinked with the hole transport layer material.

[0007] Optionally, the electroluminescent device includes a first pixel region, a second pixel region, and a third pixel region; the perovskite quantum dot light-emitting layer includes MAPbI x Br 3-x quantum dots located in the first pixel region, MAPbBr3 quantum dots located in the second pixel region, and MAPbCl x Br 3-x quantum dots located in the third pixel region.

[0008] Optionally, the MAPbI x Br 3-x quantum dots, the MAPbBr3 quantum dots, and the MAPbCl x Br 3-x quantum dots are all modified with short-chain ligands.

[0009] Optionally, the material of the hole transport layer is one of TFB, PVK, and Spiro-MeOTAD.

[0010] In a second aspect, based on the same inventive concept, the present application provides the following technical solution through an embodiment:

[0011] A method for manufacturing an electroluminescent device, the method comprising:

[0012] Providing a substrate;

[0013] Forming an electron transport layer on the substrate;

[0014] Forming a perovskite quantum dot light-emitting layer and a hole transport layer on the electron transport layer; the perovskite quantum dot light-emitting layer is located between the electron transport layer and the hole transport layer, and the hole transport layer includes a cross-linking agent cross-linked with the hole transport layer material.

[0015] Optionally, the electroluminescent device includes a first pixel region, a second pixel region, and a third pixel region; the perovskite quantum dot light-emitting layer includes MAPbI x Br 3-x quantum dots located in the first pixel region, MAPbBr3 quantum dots located in the second pixel region, and MAPbCl x Br 3-x quantum dots located in the third pixel region;

[0016] The forming of the perovskite quantum dot light-emitting layer and the hole transport layer on the electron transport layer includes:

[0017] Forming the MAPbI x Br 3-x quantum dots and a first hole transport layer stacked on the MAPbI x Br 3-x quantum dots in the first pixel region;

[0018] Forming the MAPbBr3 quantum dots and a second hole transport layer stacked on the MAPbBr3 quantum dots in the second pixel region;

[0019] Forming the MAPbCl x Br 3-x quantum dots and a third hole transport layer stacked on the MAPbCl x Br 3-x quantum dots in the third pixel region.

[0020] Optionally, the forming of the MAPbI x Br3-x Quantum dots and a first hole transport layer stacked on the MAPbI x Br 3-x quantum dots, comprising:

[0021] Coating MAPbI x Br 3-x quantum dots on the electron transport layer;

[0022] Coating a first hole transport material on the MAPbI x Br 3-x quantum dots, wherein the first hole transport material contains a photosensitive crosslinking agent;

[0023] Exposing the first hole transport material located in the first pixel region, and then developing the first hole transport material using an orthogonal solvent to dissolve the first hole transport material located in the second pixel region and the third pixel region, so as to obtain MAPbI located in the first pixel region, the second pixel region and the third pixel region x Br 3-x quantum dots, and a first hole transport layer located in the first pixel region and stacked on the MAPbI x Br 3-x quantum dots.

[0024] Optionally, the coating of the first hole transport material on the MAPbI x Br 3-x quantum dots includes:

[0025] Soaking a short-chain ligand solution on the surface of the MAPbI x Br 3-x quantum dots to obtain MAPbI modified with short-chain ligands x Br 3-x quantum dots;

[0026] Coating the first hole transport material on the MAPbI x Br 3-x quantum dots modified with short-chain ligands.

[0027] Optionally, the formation of the MAPbBr3 quantum dots and the second hole transport layer stacked on the MAPbBr3 quantum dots in the second pixel region includes:

[0028] Soaking the MAPbI x Br 3-x quantum dots with tetrabutylammonium bromide solution, so that the MAPbI not stacked by the first hole transport layer x Br 3-xThe quantum dots are subjected to a halogen exchange with the tetrabutylammonium bromide solution to obtain MAPbBr3 quantum dots located in the second pixel region and the third pixel region;

[0029] A second hole transport material containing a photosensitive crosslinking agent is coated on the MAPbBr3 quantum dots;

[0030] The second hole transport material located in the second pixel region is exposed, and then the second hole transport material is developed using an orthogonal solvent to dissolve the second hole transport material located in the third pixel region, obtaining a second hole transport layer located in the second pixel region and stacked on the MAPbBr3 quantum dots.

[0031] Optionally, forming the MAPbCl x Br 3-x quantum dots and a third hole transport layer stacked on the MAPbCl x Br 3-x quantum dots includes:

[0032] The MAPbBr3 quantum dots are soaked in a tetrabutylammonium chloride solution to subject the MAPbBr3 quantum dots not stacked by the second hole transport layer to a halogen exchange with the tetrabutylammonium chloride solution, obtaining MAPbCl x Br 3-x quantum dots;

[0033] On the MAPbCl x Br 3-x quantum dots, a third hole transport material containing a photosensitive crosslinking agent is coated;

[0034] The third hole transport material located in the third pixel region is exposed, and then the third hole transport material is developed using an orthogonal solvent to dissolve the third hole transport material outside the third pixel region, obtaining a third hole transport layer located in the third pixel region and stacked on the MAPbCl x Br 3-x quantum dots.

[0035] In a third aspect, based on the same inventive concept, the present application provides the following technical solution through an embodiment:

[0036] A display panel includes any one of the electroluminescent devices provided in the first aspect.

[0037] In a fourth aspect, based on the same inventive concept, the present application provides the following technical solution through an embodiment:

[0038] A display device includes a display panel provided by a third aspect.

[0039] Through one or more technical solutions of the present invention, the present invention has the following beneficial effects or advantages:

[0040] The present invention provides an electroluminescent device, which includes a stacked electron transport layer, a perovskite quantum dot light-emitting layer, and a hole transport layer; the perovskite quantum dot light-emitting layer is located between the electron transport layer and the hole transport layer, and the hole transport layer includes a cross-linking agent cross-linked with the hole transport layer material. In the electroluminescent device provided by the present invention, by using the cross-linking of the cross-linking agent and the hole transport layer, the hole transport layer can be used not only to collect and transport holes without affecting the performance of the electroluminescent device, but also as a mask (Mask) for the perovskite quantum dot light-emitting layer during the patterning process; since no photoresist is used as the Mask anymore, the problem that holes or electrons are difficult to inject into the perovskite quantum dot light-emitting layer caused by the residual insulating photoresist on the perovskite quantum dot light-emitting layer is solved, thereby improving the injection efficiency of carriers and the display effect.

[0041] The above description is only an overview of the technical solutions of the present invention. In order to be able to understand the technical means of the present invention more clearly, it can be implemented according to the content of the specification. And in order to make the above and other purposes, features, and advantages of the present invention more obvious and understandable, the following specific embodiments of the present invention are specifically exemplified. Description of the Drawings

[0042] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Moreover, throughout the drawings, the same reference numerals are used to represent the same components.

[0043] In the drawings:

[0044] Figure 1 Shows a schematic structural diagram of an electroluminescent device provided according to an embodiment of the present invention;

[0045] Figure 2 Shows a schematic structural diagram of an electroluminescent device including an anode layer, a cathode layer, and a hole injection layer provided according to an embodiment of the present invention;

[0046] Figure 3 Shows a schematic flow diagram of a manufacturing method of an electroluminescent device provided according to an embodiment of the present invention;

[0047] Figure 4 Shows a schematic diagram of forming MAPbI x Br 3-x Quantum dots on the electron transport layer;

[0048] Figure 5 Shows a schematic diagram of soaking MAPbI with a short-chain ligand solution according to an embodiment of the present invention x Br 3-x Quantum dots;

[0049] Figure 6 Shows a schematic diagram of MAPbI with long-chain ligands according to an embodiment of the present invention x Br 3-x Quantum dot schematic;

[0050] Figure 7 Shows a schematic diagram of coating a hole transport material on MAPbI x Br 3-x Quantum dots;

[0051] Figure 8 Shows a schematic diagram after exposing the R pixel region and developing the G and B pixel regions according to an embodiment of the present invention;

[0052] Figure 9 Shows a schematic diagram of converting MAPbI in the R and B pixel regions to MAPbBr3 quantum dots by in-situ halogen exchange according to an embodiment of the present invention x Br 3-x Quantum dots;

[0053] Figure 10 Shows a schematic diagram of coating a hole transport material on MAPbBr3 quantum dots according to an embodiment of the present invention;

[0054] Figure 11 Shows a schematic diagram after exposing the G pixel region and developing the B pixel region according to an embodiment of the present invention;

[0055] Figure 12 Shows a schematic diagram of converting MAPbBr3 quantum dots in the B pixel region to MAPbCl x Br 3-x Quantum dots;

[0056] Figure 13 Shows a schematic diagram of coating a hole transport material on MAPbCl x Br 3-x Quantum dots;

[0057] Figure 14 Shows a schematic diagram after exposing and developing the B pixel region according to an embodiment of the present invention;

[0058] Description of the reference numerals in the drawings:

[0059] 1. Electron transport layer; 2. Perovskite quantum dot light-emitting layer; 21. MAPbI x Br 3-x Quantum dots; 22. MAPbBr3 quantum dots; 23. MAPbCl x Br 3-x Quantum dots; 3. Hole transport layer; 31. First hole transport layer; 32. Second hole transport layer; 33. Third hole transport layer; 4. First electrode layer; 5. Hole injection layer; 6. Second electrode layer. Detailed implementation manners

[0060] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present disclosure.

[0061] Various schematic structural diagrams according to embodiments of the present disclosure are shown in the drawings. These figures are not drawn to scale, where for the purpose of clear expression, some details are enlarged and some details may be omitted. The shapes of various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary. In practice, there may be deviations due to manufacturing tolerances or technical limitations, and those skilled in the art can design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0062] In the context of the present disclosure, when a layer / component is referred to as being "on" another layer / component, the layer / component can be directly on the other layer / component, or there can be an intermediate layer / component between them. Additionally, if a layer / component is "on" another layer / component in one orientation, then when the orientation is reversed, the layer / component can be "under" the other layer / component.

[0063] To solve the problem that it is difficult for holes or electrons to be injected into the light-emitting layer due to the photoresist acting as a mask Mask, in a first aspect, in an optional embodiment, please refer to Figures 1 - 2 , a light-emitting device is provided, including a stacked electron transport layer 1, a perovskite quantum dot light-emitting layer 2, and a hole transport layer 3; the perovskite quantum dot light-emitting layer 2 is located between the electron transport layer 1 and the hole transport layer 3, and the hole transport layer 3 includes a crosslinking agent crosslinked with the material of the hole transport layer 3.

[0064] Among them, the electron transport layer 1, as a functional layer for transporting electrons, is often formed on a substrate using electron transport materials such as ZnO and ZnMgO. In the field of QLED displays, the substrate can be an indium tin oxide (ITO) substrate. In addition, electron transport materials such as SnO2, TiO2, BaNO3, and SrTiO3 can also be used to manufacture the electron transport layer 1. Unless otherwise specified, in this embodiment, ZnO or ZnMgO is used to manufacture the electron transport layer 1. It should be noted that ZnO and ZnMgO are difficult to develop using solvents after film formation, so they cannot be used as a patterning mask.

[0065] In this embodiment, the light-emitting layer of the electroluminescent device is a perovskite quantum dot light-emitting layer 2. Among them, the quantum dot light-emitting layer is a light-emitting structure with quantum dot materials (Quantum Dots) as the core. Quantum dots include an inorganic light-emitting center and a surface ligand: the inorganic light-emitting center is a compound with a perovskite structure; the surface ligand is usually an organic material, which is modified on the inorganic light-emitting center. By changing the ligand material, the perovskite quantum dot material can be dissolved in various organic solvents. Currently, perovskite quantum dots are a hot research field in QLED display technology. Compared with metal chalcogenide quantum dots, perovskite quantum dots are more tolerant of defects and have excellent photoluminescence quantum yields and high color purity. Perovskite quantum dots are semiconductor nanocrystals, and their compound general formula is: ABX3, where A is a cation, including but not limited to: any one or more of organic amine groups, formamidine, and cesium ions; B is a metal cation, including but not limited to: lead ions or tin ions; X is a halogen anion, including but not limited to: one or more of chlorine, bromine, and iodine. By adjusting the type and ratio of X: halogen elements, the emission wavelength of perovskite quantum dots can be controlled. For example: MAPbBr3 emits green light, MAPbCl x Br 3-x emits blue light, MAPbI x Br 3-x emits red light.

[0066] Currently, displays achieve color display through the arrangement of three primary colors: RGB pixels. Therefore, the electroluminescent device includes a first pixel region, a second pixel region, and a third pixel region; the first pixel region, the second pixel region, and the third pixel region can be respectively configured as Red (red) pixels, Green (green) pixels, and Blue (blue) pixels, or can be configured according to other RGB arrangement schemes. Taking the former as an example, the perovskite quantum dot light-emitting layer 2 includes MAPbI located in the first pixel region x Br 3-x quantum dots 21, which emit red light after carrier recombination; MAPbBr3 quantum dots 22 located in the second pixel region, which emit green light after carrier recombination; MAPbCl located in the third pixel region x Br3-x The quantum dots 23 emit blue light after carrier recombination. The optional thickness of the perovskite quantum dot light-emitting layer 2 is 10 - 60 nm.

[0067] In this embodiment, the hole transport layer 3 is used as a functional layer for collecting and transporting holes on the one hand, and as a mask for patterning the perovskite quantum dot light-emitting layer 2 on the other hand. Therefore, the hole transport layer 3 can be made of hole transport organic materials such as TFB (1,2,4,5-Tetrakis(trifluoromethyl)benzene), PVK (Poly(N-vinylcarbazole)), Spiro-MeOTAD (2,2',7,7'-tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene), etc. The crosslinking agent added to the hole transport layer 3 is also called a bridging agent, and includes but is not limited to photosensitive crosslinking agents and thermosensitive crosslinking agents according to type; the photosensitive crosslinking agent undergoes a crosslinking reaction with the hole transport layer 3 through exposure, and the thermosensitive crosslinking agent undergoes a crosslinking reaction with the hole transport layer 3 through heating; after the crosslinking reaction, bridge bonds are formed between the polymer molecular chains of the hole transport layer 3, turning the hole transport layer 3 that has undergone the crosslinking reaction into a compound that is insoluble or hardly soluble in the developer. Therefore, the hole transport layer 3 containing the crosslinking agent can not only be used as the hole transport layer 3 of the electroluminescent device, but also be used as a mask during the patterning of the perovskite quantum dot light-emitting layer 2, that is, in-situ halogen exchange, and does not affect the hole transport performance.

[0068] Therefore, this embodiment provides an electroluminescent device, including a stacked electron transport layer 1, a perovskite quantum dot light-emitting layer 2, and a hole transport layer 3; the perovskite quantum dot light-emitting layer 2 is located between the electron transport layer 1 and the hole transport layer 3, and the hole transport layer 3 includes a crosslinking agent crosslinked with the material of the hole transport layer 3. In the electroluminescent device provided by this embodiment, by using the crosslinking of the crosslinking agent with the hole transport layer 3, the hole transport layer 3 can be used to collect and transport holes without affecting the performance of the electroluminescent device, and can also be used as a mask during the patterning process of the perovskite quantum dot light-emitting layer 2; since no photoresist is used as a mask, the problem that holes or electrons are difficult to inject into the perovskite quantum dot light-emitting layer 2 caused by the residual insulating photoresist on the perovskite quantum dot light-emitting layer 2 is solved, thereby improving the injection efficiency of carriers and the display effect.

[0069] In some alternative embodiments, such as Figure 2As shown, the electroluminescent device further includes a first electrode layer 4, a hole injection layer 5, and a second electrode layer 6; the electron transport layer 1, the perovskite quantum dot light-emitting layer 2, and the hole transport layer 3 are stacked between the first electrode layer 4 and the hole injection layer 5, and the hole injection layer 5 is located between the second electrode layer 6 and the hole transport layer 3. Among them, the first electrode layer 4 can be a cathode layer, and the second electrode layer 6 can be an anode layer.

[0070] In some alternative embodiments, MAPbI x Br 3-x quantum dots 21, MAPbBr3 quantum dots 22, and MAPbCl x Br 3-x quantum dots 23 are all modified with short-chain ligands. Currently, long-chain ligands such as soluble oleic acid (OA) or oleylamine (OAM) are often used to passivate perovskite quantum dots. However, long-chain ligands are not conducive to charge transport between perovskite quantum dots and are prone to generating dangling bond defects on the surface of the quantum dots, reducing the performance of the electroluminescent device. By means of in-situ halogen ion exchange and in-situ ligand exchange, long-chain ligands can be replaced with short-chain ligands while regulating the emission wavelength of the perovskite light-emitting layer. A short-chain ligand refers to a ligand with a chain length of 2 to 4, which can improve the photoluminescence quantum yield (PLQY) and carrier injection ability of the quantum dot light-emitting layer, thereby further improving the display effect.

[0071] Based on the same inventive concept, in a second aspect, in another alternative embodiment, please refer to Figure 3 , a manufacturing method of an electroluminescent device is provided, including:

[0072] S301: Provide a substrate; the substrate can use an ITO substrate commonly used in the field of LED displays.

[0073] S302: Form an electron transport layer 1 on the substrate;

[0074] Specifically, the electron transport layer 1 can be prepared on the ITO substrate by spin coating, inkjet printing, or blade coating, and the material of the electron transport layer 1 can be ZnO or ZnMgO.

[0075] Optionally, before forming the electron transport layer 1, the substrate can be cleaned, dried, and baked to passivate the surface defects of the substrate, improve the density or integrity of the subsequent formed film layer structure, and reduce the generation of defects.

[0076] S303: Form a perovskite quantum dot light-emitting layer 2 and a hole transport layer 3 on the electron transport layer 1; the perovskite quantum dot light-emitting layer 2 is located between the electron transport layer 1 and the hole transport layer 3, and the hole transport layer 3 includes a crosslinking agent crosslinked with the material of the hole transport layer 3.

[0077] Specifically, the perovskite (ABX3) light-emitting layer can be coated on the film of the electron transport layer 1 by spin coating, inkjet printing, or blade coating. By adjusting the solution concentration of the perovskite quantum dots and the coating process, the film thickness of the perovskite quantum dot light-emitting layer 2 can be controlled. By adjusting the type or ratio of X halogens in the perovskite, the emission wavelength of the perovskite quantum dot light-emitting layer 2 can be controlled.

[0078] Next, a hole transport layer 3 is coated on the perovskite quantum dot light-emitting layer 2, and the thickness of the hole transport layer 3 is 10 nm to 30 nm. A crosslinking agent is added to the hole transport material solution. Taking a photosensitive crosslinking agent as an example, a compound containing an azide group, that is, a compound with three nitrogen-linked structures (RN3), such as ethane-1,2-diyl bis(4-azido-2,3,5,6-tetrafluorobenzoate), can be used; a compound such as benzophenone that can crosslink with adjacent quantum dot ligands under light irradiation can also be used. After exposure, the crosslinking agent in the irradiated area will crosslink with the hole transport material, enabling the hole transport layer 3 to be used as a mask when patterning the perovskite quantum dot light-emitting layer 2.

[0079] Currently, the display scheme of QLED often adopts the RGB pixel arrangement. Therefore, optionally, the electroluminescent device includes a first pixel region, a second pixel region, and a third pixel region; the perovskite quantum dot light-emitting layer 2 includes MAPbI x Br 3-x quantum dots 21 located in the first pixel region, MAPbBr3 quantum dots 22 located in the second pixel region, and MAPbCl x Br 3-x quantum dots 23 located in the third pixel region. The first pixel region serves as the first type of pixel (such as R) in the RGB pixels, the second pixel region serves as the second type of pixel (such as G) in the RGB pixels, and the first pixel region serves as the third type of pixel (such as B) in the RGB pixels.

[0080] Optionally, forming the perovskite quantum dot light-emitting layer 2 and the hole transport layer 3 on the electron transport layer 1 is essentially a patterning process for the perovskite quantum dot light-emitting layer 2, specifically including:

[0081] Forming MAPbI x Br 3-x quantum dots 21 and the first hole transport layer stacked on the MAPbI x Br 3-x quantum dots 21 in the first pixel region; forming MAPbBr3 quantum dots 22 and the second hole transport layer stacked on the MAPbBr3 quantum dots 22 in the second pixel region; forming MAPbCl x Br 3-x quantum dots 23 and the layer stacked on MAPbClx Br 3-x The third hole transport layer on the quantum dot 23.

[0082] In some embodiments, in-situ halogen exchange can be used to adjust the type and content of halogen elements in the perovskite material to form MAPbI x Br 3-x quantum dots 21, MAPbBr3 quantum dots 22 located in the second pixel region, and MAPbCl x Br 3-x quantum dots 23.

[0083] Then, the steps of forming MAPbI x Br 3-x quantum dots 21 and the first hole transport layer stacked on the MAPbI x Br 3-x quantum dots 21 specifically include:

[0084] 3031: Coating MAPbI x Br 3-x quantum dots 21 on the electron transport layer 1;

[0085] Among them, MAPbI x Br 3-x quantum dots 21 are located in the first pixel region, the second pixel region, and the third pixel region.

[0086] 3032: Coating the first hole transport material on the MAPbI x Br 3-x quantum dots 21, and the first hole transport material contains a photosensitive crosslinking agent; similarly, the first hole transport material is located in the first pixel region, the second pixel region, and the third pixel region.

[0087] Optionally, 3032: The step of coating the first hole transport material on the MAPbI x Br 3-x quantum dots 21 specifically includes: Immersing the surface of the MAPbI x Br 3-x quantum dots 21 in a short-chain ligand solution to obtain MAPbI x Br 3-x quantum dots 21 modified with short-chain ligands; Coating the first hole transport material on the MAPbI x Br 3-x quantum dots 21 modified with short-chain ligands.

[0088] In the current perovskite quantum dot light-emitting layer 2, long-chain ligands are usually selected as ligands, such as soluble oleic acid or oleylamine. However, long-chain ligands are not conducive to charge transport between perovskite quantum dots and generate dangling bond defects on the surface, reducing the device performance. In this step, before coating the hole transport material, the long-chain ligands on the perovskite quantum dots are in-situ replaced with short-chain ligands, thus achieving: 1) improving the carrier transport efficiency; 2) passivating the surface defects of the perovskite quantum dot light-emitting layer 2; 3) selecting a suitable ligand according to the solvent of the subsequent film layer: the hole transport layer 3, adjusting the solubility of the perovskite light-emitting layer in the solvent of the subsequent process, and preventing the perovskite light-emitting layer from being damaged.

[0089] 3033: Expose the first hole transport material in the first pixel region, and then perform a development process on the first hole transport material using an orthogonal solvent to dissolve the first hole transport material in the second pixel region and the third pixel region, obtaining MAPbI located in the first pixel region, the second pixel region, and the third pixel region x Br 3-x quantum dots 21, and the first hole transport layer located in the first pixel region and stacked on the MAPbI x Br 3-x quantum dots 21.

[0090] It should be noted that the selection of the hole transport material needs to consider the selection of the perovskite quantum dots and the cross-linking agent in combination, and the developing solvent should consider the hole transport material before and after cross-linking, and select an orthogonal solvent for the perovskite quantum dots. The orthogonal solvent for the perovskite quantum dots refers to a developing solvent that can dissolve the upper layer material, that is, the hole transport material before cross-linking, and cannot dissolve the lower layer material, that is, the perovskite quantum dot light-emitting layer material, and also cannot dissolve the hole transport material after cross-linking during the developing process. Therefore, during the developing process, the first hole transport material in the exposed area: the first pixel region is retained, while the first hole transport material in the unexposed area: the second pixel region and the third pixel region is removed, exposing the bottom MAPbI x Br 3-x quantum dots 21. Therefore, after this step is completed, MAPbI located in the first pixel region, the second pixel region, and the third pixel region is formed on the electron transport layer 1 x Br 3-x quantum dots 21 and the first hole transport layer located in the first pixel region and stacked on the MAPbI x Br 3-x quantum dots 21.

[0091] For perovskite materials of the MAPbX3 type, any one of TFB, PVK, and Spiro-MeOTAD can be selected as the hole transport material, an azide group compound can be used as the photosensitive crosslinking agent, and toluene or chlorobenzene can be selected as the orthogonal solvent. It should be noted that the solubility of perovskite materials in different solvents can be adjusted through ligand exchange. For example, replacing the oleic acid or oleylamine ligand of the perovskite material MAPbX3 with the MMES (mono-2-(methacryloyloxy)ethyl succinate) ligand can make it soluble in PGMEA (propylene glycol methyl ether acetate), but its solubility in toluene is low; quantum dots modified with carboxyl groups can also resist the flushing of toluene; therefore, the selection of the orthogonal solvent can be flexibly adjusted according to the actual situation.

[0092] Next: The specific steps for forming MAPbBr3 quantum dots 22 and a second hole transport layer stacked on the MAPbBr3 quantum dots 22 in the second pixel region include:

[0093] 3034: Soak MAPbI x Br 3-x quantum dots 21 so that the MAPbI x Br 3-x quantum dots 21 that are not stacked by the first hole transport layer undergo a halogen exchange with the tetrabutylammonium bromide solution to obtain MAPbBr3 quantum dots 22 located in the second pixel region and the third pixel region.

[0094] Specifically, 3034 realizes the transformation of perovskite materials through an in-situ halogen exchange method. The tetrabutylammonium bromide solution can be coated on the surface of the exposed MAPbI x Br 3-x quantum dots 21. Through the in-situ exchange of halogens, the MAPbI x Br 3-x quantum dots 21 can be transformed into MAPbBr3 quantum dots 22. At this time, due to the existence of the crosslinked first hole transport layer in the first pixel region, under the blocking effect of the first hole transport layer, only the MAPbI x Br 3-x quantum dots 21 at the second pixel region and the third pixel region will be transformed into MAPbBr3 quantum dots 22 due to the in-situ halogen exchange.

[0095] 3035: Coat a second hole transport material on the MAPbBr3 quantum dots 22, and the second hole transport material contains a photosensitive crosslinking agent;

[0096] The implementation principle of this step is the same as that of 3032, and will not be elaborated here.

[0097] Optionally, step 3035 specifically includes: soaking the surface of the MAPbBr3 quantum dots 22 in a short-chain ligand solution to obtain MAPbBr3 quantum dots 22 modified with short-chain ligands; coating a second hole transport material on the MAPbBr3 quantum dots 22 modified with short-chain ligands.

[0098] Specifically, during the in-situ halogen exchange process, some of the short-chain ligands in the MAPbI x Br 3-x quantum dots 21 in the second pixel region and the third pixel region may be partially converted into long-chain ligands. Therefore, in-situ ligand exchange can be performed again before coating the second hole transport material to further replace the long-chain ligands of the MAPbBr3 quantum dots 22 with short-chain ligands.

[0099] 3036: Expose the second hole transport material in the second pixel region, and then develop the second hole transport material with an orthogonal solvent to dissolve the second hole transport material in the third pixel region, obtaining a second hole transport layer located in the second pixel region and stacked on the MAPbBr3 quantum dots 22.

[0100] Since the first hole transport layer in the first pixel region and the second hole transport layer in the second pixel region have already undergone a crosslinking reaction with the crosslinking agent, only the unexposed second hole transport material is removed by the orthogonal solvent during the development process of this step. After step 3036 is completed, on the electron transport layer 1, there are formed MAPbI x Br 3-x quantum dots 21 and the first hole transport layer in the first pixel region, MAPbBr3 quantum dots 22 and the second hole transport layer in the second pixel region, and MAPbBr3 quantum dots 22 in the third pixel region.

[0101] Similarly, the specific steps for forming MAPbCl x Br 3-x quantum dots 23 and the third hole transport layer stacked on the MAPbCl x Br 3-x quantum dots 23 in the third pixel region include:

[0102] 3037: Soak the MAPbBr3 quantum dots 22 in a tetrabutylammonium chloride solution to allow the MAPbBr3 quantum dots 22 not stacked by the second hole transport layer to undergo halogen exchange with the tetrabutylammonium chloride solution, obtaining MAPbCl x Br 3-x quantum dots 23 in the third pixel region.

[0103] Specifically, a tetrabutylammonium chloride solution can be coated on the MAPbBr3 quantum dots 22 located in the third pixel region. Blocked by the first hole transport layer and the second hole transport layer, only the MAPbBr3 quantum dots 22 in the third pixel region will undergo in-situ halogen exchange with the tetrabutylammonium chloride solution and transform into MAPbCl x Br 3-x quantum dots 23.

[0104] 3038: Coat a third hole transport material on the MAPbCl x Br 3-x quantum dots 23. The third hole transport material contains a photosensitive crosslinking agent;

[0105] Optionally, the steps of 3038 specifically include: Immerse the surface of the MAPbCl x Br 3-x quantum dots 23 in a short-chain ligand solution to obtain MAPbCl x Br 3-x quantum dots 23 modified with short-chain ligands; Coat the third hole transport material on the MAPbCl x Br 3-x quantum dots 23 modified with short-chain ligands.

[0106] Specifically, during the in-situ halogen exchange process, some of the short-chain ligands in the MAPbBr3 quantum dots 22 may be partially converted into long-chain ligands. Therefore, before coating the third hole transport material, in-situ ligand exchange can be performed again to further replace the long-chain ligands in the MAPbCl x Br 3-x quantum dots 23 with short-chain ligands.

[0107] 3039: Expose the third hole transport material located in the third pixel region, and then use an orthogonal solvent to develop the third hole transport material to dissolve the third hole transport material located outside the third pixel region, obtaining a third hole transport layer located in the third pixel region and stacked on the MAPbCl x Br 3-x quantum dots 23.

[0108] Specifically, through the exposure and development of 3039, the crosslinked third hole transport material in the third pixel region can be retained, and the unexposed third hole transport material located at other positions can be removed.

[0109] It should be noted that the first hole transport material, the second hole transport material, and the third hole transport material coated in this solution can have the same or different materials. The photosensitive crosslinking agent is adjusted according to the material of the hole transport material, and there is no limitation here.

[0110] This embodiment provides a method for manufacturing an electroluminescent device. By forming a hole transport layer 3 containing a crosslinking agent on the perovskite quantum dot light-emitting layer 2, the crosslinking agent can be used as a mask during the patterning of the perovskite quantum dot light-emitting layer 2 and the in-situ halogen exchange of perovskite quantum dots after undergoing a crosslinking reaction with the material of the hole transport layer 3. There is no need to use a photoresist as a mask, avoiding the problem that holes or electrons are difficult to inject into the perovskite quantum dot light-emitting layer 2 caused by the residual photoresist on the perovskite quantum dot light-emitting layer 2, and improving the injection efficiency of carriers. At the same time, the crosslinked hole transport layer 3 can also collect and transport holes without affecting the performance of the electroluminescent device.

[0111] Further, before coating the hole transport material on the perovskite quantum dots, replacing the long-chain ligands on the perovskite quantum dots with short-chain ligands through in-situ ligand replacement can improve the carrier transport efficiency, passivate the surface defects of the perovskite quantum dot light-emitting layer 2, and adjust the solubility of the perovskite quantum dots in the solvents of subsequent processes, preventing the perovskite quantum dot light-emitting layer 2 from being damaged.

[0112] To more intuitively illustrate the above scheme, next, in combination with specific material selection, process, and drawings, the manufacturing method provided in this embodiment will be further described:

[0113] Material selection description:

[0114] Substrate: ITO substrate;

[0115] Electron transport layer 1: ZnO or ZnMgO;

[0116] Perovskite quantum dot light-emitting layer 2, including: R pixel: MAPbI x Br 3-x Quantum dots 21; G pixel: MAPbBr3 quantum dots 22; B pixel: MAPbCl x Br 3-x Quantum dots 23;

[0117] Hole transport layer 3: One of TFB, PVK, Spiro-MeOTAD;

[0118] Photosensitive crosslinking agent: ethane-1,2-diyl bis(4-azido-2,3,5,6-tetrafluorobenzoate);

[0119] Orthogonal solvent: Toluene or chlorobenzene.

[0120] The specific manufacturing process of the electroluminescent device is as follows:

[0121] 1) Use deionized water and isopropyl alcohol to ultrasonically clean the ITO substrate for 15 minutes respectively, then dry it with nitrogen and bake it at 135 °C for 5 minutes.

[0122] 2) Treat the ITO substrate with ultraviolet ozone for 10 minutes to further clean the organic pollutants attached to the ITO surface and passivate the surface defects of the ITO.

[0123] 3) Prepare ZnO or ZnMgO on the ITO substrate by spin coating as the electron transport layer 1 with a thickness of 30 nm to 50 nm.

[0124] 4) Use the perovskite quantum dot solution to coat and form MAPbI x Br 3-x quantum dots 21 with a thickness of 10 nm to 60 nm, as Figure 4 shown; then heat and bake at 70 °C to 120 °C for 5 to 20 minutes to dry and densify the film layer of MAPbI x Br 3-x quantum dots 21.

[0125] 5) Use a short-chain ligand solution, such as acetate solution, to clean the MAPbI x Br 3-x quantum dots 21 for the first ligand replacement, and then drop 3 ml of the short-chain ligand solution on the surface of MAPbI x Br 3-x quantum dots 21 and soak for 2 minutes (as Figure 5 shown), so as to replace the oleic acid and / or oleylamine ligands on the MAPbI x Br 3-x quantum dots 21 with short-chain ligands. The structural schematic of the MAPbI x Br 3-x quantum dots 21 with long-chain ligands can be referred to Figure 6 ; after the ligand replacement, spin-dry the sample. By in-situ replacing the long-chain ligands of the MAPbI x Br 3-x quantum dots 21 with short-chain ligands, it can: ① improve the carrier transport efficiency; ② passivate the surface defects of the MAPbI x Br 3-x quantum dots 21; ③ adjust the solubility of the MAPbI x Br 3-x quantum dots 21 in the solvents of subsequent processes to prevent the quantum dot layer from being damaged.

[0126] 6) Use the hole transport material solution to coat the hole transport material on the MAPbI x Br 3-x quantum dots 21 with a thickness of 10 nm to 30 nm, as Figure 7 shown; among them, a photosensitive crosslinking agent is added to the hole transport material solution, and the crosslinking agent in the illuminated area will crosslink the hole transport material after exposure.

[0127] 7) Expose the hole transport material in the R pixel region to crosslink the hole transport material in the R pixel region with the photosensitive crosslinking agent; then use an orthogonal solvent of perovskite quantum dots: toluene or chlorobenzene to develop all the hole transport materials. At this time, the hole transport material in the exposed area (R pixel region) remains to form the first hole transport layer 31, and the hole transport materials in the unexposed areas (G pixel region, B pixel region) are removed, exposing the bottom MAPbI x Br 3-x quantum dots 21, as Figure 8 shown.

[0128] 8) Immerse the sample obtained in 7) in 3 - 5 ml of tetrabutylammonium bromide solution for 2 minutes, then rinse with solvent and spin - dry. Through in - situ halogen substitution, the MAPbI x Br 3-x quantum dots 21 in the G and B pixel regions are transformed into MAPbBr3 quantum dots 22; then immerse in 3 ml of short - chain ligand solution for 2 minutes to further replace the long - chain ligand of MAPbBr3 with a short - chain ligand, as Figure 9 shown.

[0129] 9) Coat a hole transport material on the MAPbBr3 quantum dots 22, and a photosensitive crosslinking agent is added to the hole transport material solution, as Figure 10 shown.

[0130] 10) Expose the G pixel region, and the crosslinking agent in the G pixel region will crosslink with the hole transport material. Use an orthogonal solvent for development. The exposed area: the second hole transport layer 32 in the G pixel region is retained, and the unexposed area: the hole transport material in the B pixel region is removed, exposing the MAPbBr3 quantum dots 22 in the B pixel region, as Figure 11 shown.

[0131] 11) Immerse the sample obtained in step 10) in 3 - 5 ml of tetrabutylammonium chloride solution for 2 minutes, then rinse with solvent and spin - dry. Through in - situ halogen exchange, the MAPbBr3 quantum dots 22 in the B pixel region are changed to MAPbCl x Br 3-x quantum dots 23, and immerse in 3 ml of short - chain ligand solution for 2 minutes to further replace the long - chain ligand of MAPbCl x Br 3-x quantum dots 23 with a short - chain ligand, as Figure 12 shown.

[0132] 12) Coat a hole transport material on the MAPbCl x Br 3-x quantum dot 23 thin film, and a photosensitive crosslinking agent is added to the hole transport material solution, asFigure 13 as shown

[0133] Expose the B pixel region, and the crosslinking agent in the B pixel region will crosslink with the hole transport material. When developing with an orthogonal solvent, the third hole transport layer 33 in the B pixel region is retained, and the excess hole transport material on the R and G pixels is removed, as Figure 14 shown

[0134] 13) Bake the sample obtained in 12) on a hot stage at 70 °C to 120 °C for 5 to 20 minutes to dry or cure the formed film layer.

[0135] 14) Place the ITO substrate on which the above-mentioned electron transport layer 1, perovskite quantum dot light-emitting layer 2, and hole transport layer 3 are formed into an evaporation machine, and at a vacuum degree of 5×10 -4 Pa to 4×10 -5 Pa, form a hole injection layer 5 and an electrode by thermal evaporation. For example, MoO3 with a thickness of 2 nm to 20 nm, preferably 5 nm to 10 nm, can be formed as the hole injection layer 5, and 100 nm to 150 nm of Ag or Al can be used as the anode.

[0136] 14) Use a cover glass and encapsulation glue to protect the light-emitting area by ultraviolet curing to obtain an electroluminescent device as Figure 2 shown

[0137] The manufacturing method of this embodiment has the following characteristics:

[0138] 1) Use perovskite quantum dots as the light-emitting layer, and change the emission wavelength of the perovskite quantum dots by in-situ halogen exchange to form an RGB pixel arrangement;

[0139] 2) When forming the hole transport layer 3, add a crosslinking agent to the hole transport material. The crosslinked hole transport material can both serve as the hole transport layer 3 and as a mask Mask in the patterning process of the perovskite quantum dot light-emitting layer 2, avoiding the residue of photoresist on the perovskite quantum dots, thereby improving the carrier injection ability;

[0140] 3) By in-situ ligand exchange, convert the long-chain ligands on the perovskite quantum dots into short-chain ligands, which can improve the PLQY and carrier injection ability of the perovskite quantum dot light-emitting layer 2;

[0141] Combining the above factors, a highly precise patterned perovskite quantum dot light-emitting layer is finally obtained, improving the display effect.

[0142] This embodiment uses MAPbI x Br 3-x quantum dots 21, MAPbBr3 quantum dots 22, MAPbCl x Br 3-xQuantum dots 23, photosensitive crosslinking agent, and orthogonal solvent: Exemplary illustration with toluene or chlorobenzene as an example. It can be understood that the above examples of material selection are not intended as specific limitations. After learning the implementation principle of the above solution, when selecting other perovskite component systems for the perovskite quantum dot light-emitting layer 2, the hole transport material, crosslinking agent, and orthogonal solvent can be flexibly adjusted according to actual needs.

[0143] For example, for the perovskite quantum dot light-emitting layer, a thermosensitive crosslinking agent can also be used as the crosslinking agent: The corresponding material selection scheme is as follows:

[0144] Hole transport layer material: A p-type hole transport material containing an alkylamine and ammonium carbamate structure, such as derivatives of TFB and PVK;

[0145] Orthogonal solvent: Chlorobenzene or toluene;

[0146] When manufacturing the electroluminescent device, the exposure step is adjusted to directly irradiate the crosslinking pixel area to be heated with a laser to trigger the crosslinking reaction between the crosslinking agent and the hole transport material. Alternatively, a patterned hot plate can be brought close to the substrate to achieve a patterning effect, making the crosslinked hole transport layer 3 serve as a mask for the perovskite quantum dots. The principles of other steps are the same as those of the above steps and will not be elaborated here.

[0147] In addition, in this embodiment, perovskite quantum dots are used as the light-emitting layer; in fact, the in-situ patterning method of the light-emitting layer through in-situ ligand exchange and in-situ halogen exchange provided in this embodiment can also be applied to the light-emitting layer of a 3D or 2D bulk perovskite thin film structure with a non-quantum dot structure.

[0148] Based on the same inventive concept, in a third aspect, in another alternative embodiment, a display panel is provided, including the electroluminescent device provided in the first aspect, or the electroluminescent device in the display panel is formed by using the manufacturing method provided in the second aspect. The display panel can be a QLED (Quantum Dot Light Emitting Diode) display panel, an OLED (Organic Light Emitting Diode) display panel, a Mini LED display panel, etc.

[0149] Based on the same inventive concept, in a fourth aspect, in another alternative embodiment, a display device is provided, including the display panel provided in the third aspect. The display device can be an OLED display, a QLED display, a Mini LED display, or various display devices equipped with the above display panel.

[0150] Among them, for the display panel provided in the third aspect embodiment and the display device provided in the fourth aspect embodiment, their technical effects are the same as those of the electroluminescent device provided in the first aspect embodiment and the manufacturing method provided in the second aspect embodiment, and will not be elaborated here.

[0151] Although the preferred embodiments of the present application have been described, additional changes and modifications can be made to these embodiments by those of ordinary skill in the art once they learn the basic creative concepts. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications that fall within the scope of the present application.

[0152] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalent technologies, the present application is also intended to include these modifications and variations.

Claims

1. A method for manufacturing an electroluminescent device, characterized in that, The method includes: providing a substrate; forming an electron transport layer on the substrate; forming a perovskite quantum dot light-emitting layer and a hole transport layer on the electron transport layer; the perovskite quantum dot light-emitting layer is located between the electron transport layer and the hole transport layer, and the hole transport layer includes a cross-linking agent cross-linked with the hole transport layer material. The electroluminescent device includes a first pixel region, a second pixel region, and a third pixel region; the perovskite quantum dot light-emitting layer includes MAPbI x Br 3-x quantum dots located in the first pixel region, MAPbBr3 quantum dots located in the second pixel region, and MAPbCl x Br 3-x quantum dots located in the third pixel region; The forming of the perovskite quantum dot light-emitting layer and the hole transport layer on the electron transport layer includes: Form the MAPbI x Br 3-x quantum dots in the first pixel region and form a first hole transport layer stacked on the MAPbI x Br 3-x quantum dots; forming the MAPbBr3 quantum dots and a second hole transport layer stacked on the MAPbBr3 quantum dots in the second pixel region; Form the MAPbCl x Br 3-x quantum dots in the third pixel region, and form a third hole transport layer stacked on the MAPbCl x Br 3-x quantum dots; Forming the MAPbI within the first pixel region x Br 3-x quantum dots and a first hole transport layer stacked on the MAPbI x Br 3-x quantum dots, comprising: Coat MAPbI x Br 3-x quantum dots on the electron transport layer; On the MAPbI x Br 3-x quantum dots, a first hole transporting material is coated, and the first hole transporting material contains a photosensitive crosslinking agent; Expose the first hole transport material located in the first pixel region, and then perform a development process on the first hole transport material using an orthogonal solvent to dissolve the first hole transport material located in the second pixel region and the third pixel region, obtaining MAPbI x Br 3-x quantum dots located in the first pixel region, and a first hole transport layer located in the first pixel region and stacked on the MAPbI x Br 3-x quantum dots; The forming of the MAPbBr3 quantum dots and the second hole transport layer stacked on the MAPbBr3 quantum dots in the second pixel region includes: Soak the MAPbI x Br 3-x quantum dots in a tetrabutylammonium bromide solution, so that the MAPbI x Br 3-x quantum dots not stacked by the first hole transport layer undergo a halogen exchange with the tetrabutylammonium bromide solution to obtain MAPbBr3 quantum dots located in the second pixel region and the third pixel region; coating a second hole transport material containing a photosensitive cross-linking agent on the MAPbBr3 quantum dots; exposing the second hole transport material located in the second pixel region, and then developing the second hole transport material with an orthogonal solvent to dissolve the second hole transport material located in the third pixel region, so as to obtain a second hole transport layer located in the second pixel region and stacked on the MAPbBr3 quantum dots.

2. The method according to claim 1, wherein The coating of the first hole transporting material on the MAPbI x Br 3-x quantum dots includes: Soak the surface of the MAPbI x Br 3-x quantum dots in a short-chain ligand solution to obtain MAPbI x Br 3-x quantum dots modified with short-chain ligands; Coat the first hole transporting material on the MAPbI x Br 3-x quantum dots modified with short-chain ligands.

3. The method according to claim 2, characterized in that, Forming the MAPbCl x Br 3-x quantum dots in the third pixel region and a third hole transport layer stacked on the MAPbCl x Br 3-x quantum dots, comprising: Soak the MAPbBr3 quantum dots with a tetrabutylammonium chloride solution, so that the MAPbBr3 quantum dots not stacked by the second hole transport layer perform halogen exchange with the tetrabutylammonium chloride solution to obtain MAPbCl x Br 3-x quantum dots in the third pixel region; On the MAPbCl x Br 3-x quantum dots, a third hole transport material is coated, and the third hole transport material contains a photosensitive crosslinking agent; Expose the third hole transport material located in the third pixel region, and then perform a development process on the third hole transport material using an orthogonal solvent to dissolve the third hole transport material located outside the third pixel region, to obtain a third hole transport layer located in the third pixel region and stacked on the MAPbCl x Br 3-x quantum dots.

4. A display panel, characterized in that, comprising an electroluminescent device according to any one of claims 1 to 3.

5. A display device, characterized in that, comprising a display panel according to claim 4.

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