Quantum dot light-emitting device, preparation method thereof and display device

Abstract

The invention provides a quantum dot light-emitting device, a preparation method thereof and a display device, and relates to the technical field of display, and the quantum dot light-emitting device comprises a first quantum dot light-emitting layer; the hole transport layer is arranged on one side of the first quantum dot light-emitting layer, and the electron transport layer is arranged on one side, deviating from the hole transport layer, of the first quantum dot light-emitting layer; wherein the first quantum dot light-emitting layer material comprises a first quantum dot, a first cross-linked structure and a second ligand, the first cross-linked structure and the second ligand are in coordination connection with the first quantum dot, the first cross-linked structure is arranged on the side, close to the electron transport layer, of the first quantum dot, and the second cross-linked structure is arranged on the side, close to the electron transport layer, of the second quantum dot. The second ligand is arranged on one side, close to the hole transport layer, of the first quantum dot.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of display technology, and specifically, to a quantum dot light-emitting device and a preparation method thereof, and a display device. Background Art

[0002] Quantum dots are a type of semiconductor nanocrystal that can be processed in a solution. They have the advantages of narrow luminescence spectrum, adjustable luminescence wavelength, and high spectral purity. They are most likely to become the core part of the next generation of light-emitting devices. Quantum dot light emitting diodes (QLEDs) use quantum dots as the material for the light-emitting layer, and introduce the light-emitting layer between different conductive materials to obtain the required wavelength of light. Their technical expertise comes from the advantages of high color gamut, self-luminescence, low starting voltage, fast response speed, and long life. It is a light-emitting display technology that is very close to commercialization in recent years. QLED is expected to enter the high-end display market first in the future, providing more accurate and vivid color performance than OLED. Summary of the invention

[0003] The embodiments of the present application provide a quantum dot light-emitting device and a method for preparing the same, and a display device, aiming to solve the problem of how to improve the efficiency of quantum dot light-emitting diode devices.

[0004] A first aspect of an embodiment of the present application provides a quantum dot light-emitting device, comprising:

[0005] a first quantum dot light-emitting layer;

[0006] A hole transport layer and an electron transport layer, wherein the hole transport layer is arranged on one side of the first quantum dot light-emitting layer, and the electron transport layer is arranged on a side of the first quantum dot light-emitting layer away from the hole transport layer;

[0007] Among them, the first quantum dot light-emitting layer material includes a first quantum dot, a first cross-linking structure and a second ligand, the first cross-linking structure and the second ligand respectively form a coordination connection with the first quantum dot, the first cross-linking structure is arranged on a side of the first quantum dot close to the electron transport layer, and the second ligand is arranged on a side of the first quantum dot close to the hole transport layer.

[0008] In an optional embodiment, the first cross-linked structure is a network structure formed by cross-linking the first ligand, wherein:

[0009] The first end of the first ligand is used for cross-linking to form the first cross-linking structure, the second end of the first ligand is used for forming a coordination connection with the first quantum dot, and the second end of the first ligand is provided with a coordination functional group.

[0010] In an optional embodiment, the first end of the second ligand is used for hole injection, the second end of the second ligand is used to form a coordination connection with the first quantum dot, and the second end of the second ligand is provided with a coordination functional group.

[0011] In an optional embodiment, the first end of the first ligand includes at least one of the following structures: a double bond, a triple bond, an acrylate bond, and ethylene oxide.

[0012] In an optional embodiment, the first end of the second ligand includes at least one of the following structures: carbazole, triarylamine, triphenylamine and fluorene.

[0013] In an optional embodiment, the coordinating functional group includes at least one of the following: a thiol group, a carboxyl group, an amino group, a polyamino group, a phosphorus oxide group and a halogen ion.

[0014] In an optional embodiment, the first ligand includes at least one of: mono[2-[(2-methyl-acryloyl)oxy]ethyl]succinate, mercaptopolyethylene glycol acrylate, 2-((2-(methacryloyloxy)ethyl)dimethylammonium)acetate, 5-hexenoic acid and 9-decenoic acid.

[0015] In an optional embodiment, the quantum dot light-emitting device further includes:

[0016] A second quantum dot light-emitting layer, wherein the second quantum dot light-emitting layer is disposed between the first quantum dot light-emitting layer and the electron transport layer, and the second quantum dot light-emitting layer material includes second quantum dots and a second cross-linked structure, wherein:

[0017] The second cross-linking structure forms a coordination connection with the second quantum dot, and the second cross-linking structure is arranged on a side of the second quantum dot close to the electron transport layer and a side of the second quantum dot close to the hole transport layer.

[0018] In an optional embodiment, the material of the first quantum dots is the same as the material of the second quantum dots; the material of the first cross-linked structure is the same as the material of the second cross-linked structure.

[0019] In an optional embodiment, the quantum dot light-emitting device further includes:

[0020] A cathode and an anode, wherein the first quantum dot light-emitting layer is disposed between the cathode and the anode, the hole transport layer is disposed between the first quantum dot light-emitting layer and the anode, and the electron transport layer is disposed between the first quantum dot light-emitting layer and the cathode;

[0021] A hole injection layer is disposed between the hole transport layer and the anode.

[0022] A second aspect of an embodiment of the present application provides a display device, comprising a plurality of quantum dot light-emitting devices as described in any one of the first aspects.

[0023] A third aspect of the embodiments of the present application provides a method for preparing a quantum dot light-emitting device, the method comprising:

[0024] providing a hole transport layer;

[0025] forming a first quantum dot light-emitting layer on one side of the hole transport layer;

[0026] forming an electron transport layer on a side of the first quantum dot light-emitting layer away from the hole transport layer;

[0027] Among them, the first quantum dot light-emitting layer material includes a first quantum dot, a first cross-linking structure and a second ligand, the first cross-linking structure and the second ligand respectively form a coordination connection with the first quantum dot, the first cross-linking structure is arranged on a side of the first quantum dot close to the electron transport layer, and the second ligand is arranged on a side of the first quantum dot close to the hole transport layer.

[0028] In an optional embodiment, forming a first quantum dot light-emitting layer on one side of the electron transport layer includes:

[0029] Spin coating a first ligand on one side of the electron transport layer;

[0030] Spin-coating a first quantum dot with a third ligand on a side of the first ligand away from the electron transport layer, so that the first ligand and the third ligand in the first quantum dot with the third ligand close to the first ligand undergo in-situ ligand exchange, forming a transition quantum dot layer;

[0031] exposing and developing the transition quantum dot layer to cause the first ligand in the transition quantum dot layer to be cross-linked to form the first cross-linked structure;

[0032] The second ligand is spin-coated on the side of the transition quantum dot layer away from the electron transport layer, so that the second ligand undergoes in-situ ligand exchange with the third ligand close to the second ligand in the transition quantum dot layer to form the first quantum dot light-emitting layer.

[0033] In an optional embodiment, the spin coating of the first ligand on one side of the electron transport layer comprises:

[0034] Spin coating the second quantum dots with the first ligand on one side of the electron transport layer, and obtaining a second quantum dot light-emitting layer through exposure treatment;

[0035] The first ligand is spin-coated on a side of the second quantum dot light-emitting layer away from the electron transport layer.

[0036] Beneficial effects:

[0037] The present application provides a quantum dot light-emitting device and a preparation method thereof, and a display device, wherein the quantum dot light-emitting device comprises: a first quantum dot light-emitting layer; a hole transport layer and an electron transport layer, wherein the hole transport layer is arranged on one side of the first quantum dot light-emitting layer, and the electron transport layer is arranged on the side of the first quantum dot light-emitting layer away from the hole transport layer; wherein the first quantum dot light-emitting layer material comprises a first quantum dot, a first cross-linking structure, and a second ligand, wherein the first cross-linking structure and the second ligand respectively form a coordination connection with the first quantum dot, the first cross-linking structure is arranged on the side of the first quantum dot close to the electron transport layer, and the second ligand is arranged on the side of the first quantum dot close to the hole transport layer. The present application effectively balances the carrier concentration of the quantum dot light-emitting layer by setting the side of the first quantum dot light-emitting layer close to the electron transport layer as a first cross-linking structure that can reduce electron injection, and the side close to the hole transport layer as a second ligand that enhances hole injection, thereby achieving an improvement in the efficiency of the quantum dot light-emitting diode device. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0039] Figure 1 This is a schematic diagram of the structure of a quantum dot light-emitting device proposed in one embodiment of the present application;

[0040] Figure 2 This is a schematic diagram of the structure of a quantum dot light-emitting device provided with a second quantum dot light-emitting layer, proposed in one embodiment of the present application;

[0041] Figure 3 This is a schematic diagram of a method for preparing a quantum dot light-emitting device according to an embodiment of the present application;

[0042] Figure 4 This is a schematic flow chart of a method for preparing a quantum dot light-emitting device with a second quantum dot light-emitting layer proposed in one embodiment of the present application;

[0043] Figure 5 It is a schematic flow chart of a method for preparing an RGB quantum dot light-emitting device proposed in one embodiment of the present application.

[0044] Explanation of the accompanying drawings: 100, first quantum dot light-emitting layer; 101, first quantum dot; 102, second ligand; 103, first cross-linked structure; 104, first ligand; 105, third ligand; 200, hole transport layer; 300, electron transport layer; 400, anode; 500, cathode; 600, hole injection layer; 700, second quantum dot light-emitting layer; 701, second quantum dot; 702, second cross-linked structure. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0046] Quantum dots are a type of semiconductor nanocrystal that can be processed in a solution. They have the advantages of narrow luminescence spectrum, adjustable luminescence wavelength, and high spectral purity. They are most likely to become the core part of the next generation of light-emitting devices. Quantum dot light emitting diodes (QLEDs) use quantum dots as the material for the light-emitting layer, and introduce the light-emitting layer between different conductive materials to obtain the required wavelength of light. Their technical expertise comes from the advantages of high color gamut, self-luminescence, low starting voltage, fast response speed, and long life. It is a light-emitting display technology that is very close to commercialization in recent years. QLED is expected to enter the high-end display market first in the future, providing more accurate and vivid color performance than OLED.

[0047] In the related technologies, direct photolithography is the most promising means to realize high-resolution QLED display products. However, in the direct photolithography process, in order to solve the problem of quantum dot residue, a cross-linking agent with strong cross-linking ability is needed to resist the washing of strong developers, which results in a large cross-linked network structure formed on the quantum dot light-emitting layer, the side where the quantum dot light-emitting layer contacts the electron transport layer, and the side where the quantum dot light-emitting layer contacts the hole transport layer. This cross-linked network structure formed after illumination blocks the transmission of electrons while also blocking the transmission of holes, thereby exacerbating the problem of carrier imbalance in QLED devices and further reducing the luminous efficiency of QLED devices.

[0048] In view of this, the present application proposes a quantum dot light-emitting device. Figure 1 A schematic diagram of the structure of a quantum dot light-emitting device proposed in one embodiment of the present application is shown. Figure 1As shown, the quantum dot light-emitting device includes: a first quantum dot light-emitting layer 100; a hole transport layer 200, wherein the hole transport layer 200 is arranged on one side of the first quantum dot light-emitting layer 100; and an electron transport layer 300, wherein the electron transport layer 300 is arranged on the side of the first quantum dot light-emitting layer 100 away from the hole transport layer 200.

[0049] In the embodiment of the present application, the material of the first quantum dot light-emitting layer 100 includes a first quantum dot 101, a first cross-linking structure 103 and a second ligand 102. The first cross-linking structure 103 and the second ligand 102 respectively form a coordination connection with the first quantum dot 101. The first cross-linking structure 103 is arranged on a side of the first quantum dot 101 close to the electron transport layer 300, and the second ligand 102 is arranged on a side of the first quantum dot 101 close to the hole transport layer 200.

[0050] Since the electron injection efficiency of the quantum dot light-emitting layer in the quantum dot light-emitting device is greater than its hole injection efficiency, the injected charge of the quantum dot light-emitting layer is unbalanced (i.e., carrier imbalance), and the quantum dots are non-neutral, resulting in a decrease in the luminous efficiency of the quantum dot light-emitting device. In the quantum dot light-emitting layer, the cross-linked structure formed by the ligands on the side close to the electron transport layer and the side close to the hole transport layer will further aggravate the problem of carrier imbalance. In the embodiment of the present application, the first quantum dot light-emitting layer 100 is provided with a first cross-linked structure 103 on the side close to the electron transport layer 300, and the first cross-linked structure 103 can reduce the electron injection efficiency of the first quantum dot light-emitting layer 100; the first quantum dot light-emitting layer 100 is provided with a second ligand 102 that does not form a cross-linked structure on the side close to the hole transport layer 200, and the second ligand 102 can enhance the hole injection efficiency of the first quantum dot light-emitting layer 100. Therefore, the quantum dot light-emitting device provided in the embodiment of the present application reduces its electron injection efficiency on the side close to the electron transport layer 300 and improves its hole injection efficiency on the side close to the hole transport layer 200, so that the carrier concentration of the first quantum dot light-emitting layer 100 tends to be balanced, thereby improving the luminous efficiency of the quantum dot light-emitting device.

[0051] In the embodiment of the present application, the first cross-linked structure 103 is a network structure formed by cross-linking the first ligand. Specifically, the first ligand is used to realize the injection of electrons into the first quantum dot light-emitting layer 100, and the first ligand includes a first end and a second end, and the first end of the first ligand is provided with a photosensitive group that can be cross-linked under light conditions, and the first end of the first ligand is used to cross-link to form the first cross-linked structure 103; the second end of the first ligand is provided with a coordination functional group, and the second end of the first ligand is used to form a coordination connection with the first quantum dot 101.

[0052] In the embodiment of the present application, a coordination connection with the first quantum dot 101 is achieved based on the second end of the first ligand, and a first cross-linked structure 103 is formed on the side of the first quantum dot 101 close to the electron transport layer 300 based on the first end of the first ligand. The first cross-linked structure 103 has a certain blocking effect on the electrons injected from the electron transport layer 300 into the first quantum dot light-emitting layer 100, thereby reducing the electron injection efficiency and effectively balancing the carrier concentration.

[0053] In an optional embodiment, the first end (photosensitive group) of the first ligand includes at least one of the following structures: a double bond, a triple bond, an acrylate bond, and ethylene oxide. The second end (coordinating functional group) of the first ligand includes at least one of the following: a thiol group, a carboxyl group, an amino group, a polyamino group, a phosphorus oxygen group, and a halogen ion.

[0054] In an optional embodiment, the first ligand includes at least one of: mono[2-[(2-methyl-acryloyl)oxy]ethyl]succinate, mercaptopolyethylene glycol acrylate, 2-((2-(methacryloyloxy)ethyl)dimethylammonium)acetate, 5-hexenoic acid and 9-decenoic acid.

[0055] It should be noted that the cross-linking of the first end of the first ligand refers to the process in which the first end of at least one first ligand undergoes a polymerization reaction to generate a first cross-linked structure under the action of light conditions and a cross-linking agent. For example, when the first ligand is succinic acid mono[2-[(2-methyl-acryloyl)oxy]ethyl] ester, the chemical reaction formula for the cross-linking of two first ligands is as follows (UV is the light condition, and the photoinitiator is the cross-linking agent):

[0056]

[0057] In an embodiment of the present application, the second ligand 102 is used to realize the injection of holes into the first quantum dot light-emitting layer 100. The second ligand 102 includes a first end and a second end. The first end of the second ligand 102 is provided with a hole transport group for hole injection; the second end of the second ligand 102 is provided with a coordination functional group, and the second end of the second ligand 102 is used to form a coordination connection with the first quantum dot 101.

[0058] In the embodiment of the present application, based on the second end of the second ligand 102, a coordination connection with the first quantum dot 101 is achieved, and based on the first end of the second ligand 102, a hole transport group that does not form a cross-linked structure is formed on the side of the first quantum dot 101 close to the hole transport layer 200, and the hole transport group injects holes injected from the hole transport layer 200 into the first quantum dot light-emitting layer 100, and different from the first cross-linked structure formed by the above-mentioned photosensitive group, the hole transport group at the first end of the second ligand does not form a cross-linked structure, so that the hole blocking effect caused by the cross-linking of the second ligand can be reduced, thereby improving the hole injection efficiency and effectively balancing the carrier concentration.

[0059] In an optional embodiment, the first end of the second ligand (hole transport group) includes at least one of the following structures: carbazole, triarylamine, triphenylamine and fluorene; the second end of the second ligand (coordinating functional group) includes at least one of the following: thiol, carboxyl, amino, polyamino, phosphoryl and halogen ion.

[0060] Exemplarily, the second ligand may be: 1-dodecylamine, carbazole-type hole transport material and triphenylamine-type hole transport material. The structural formula or general formula of the second ligand is as follows:

[0061]

[0062]

[0063] Wherein, R is independently selected from any one of a thiol group, a carboxyl group, an amino group, a polyamino group, a phosphorus oxide group and a halogen ion.

[0064] In an optional embodiment, the material of the first quantum dots includes at least one of the following: CdS, CdSe, InP, ZnSe, PbS, CsPbCl3, CsPbBr3, CsPhI3, CdS / ZnS, CdSe / ZnS, PbS / ZnS, InP / ZnS, CsPbCl3 / ZnS, CsPbBr3 / ZnS, CsPhI3 / ZnS.

[0065] In an optional embodiment, when the quantum dot light-emitting layer only includes the first quantum dot light-emitting layer 100, since it only has a single layer of first quantum dots 101, the gaps between the single layer of first quantum dots 101 may cause leakage and other undesirable phenomena, thereby affecting the light-emitting efficiency of the quantum dot light-emitting device. Therefore, the embodiment of the present application sets a second quantum dot light-emitting layer. Figure 2 A schematic diagram of the structure of a quantum dot light-emitting device with a second quantum dot light-emitting layer is shown schematically. Figure 2As shown, the quantum dot light-emitting device also includes: a second quantum dot light-emitting layer 700, which is arranged between the first quantum dot light-emitting layer 100 and the electron transport layer 300, and the material of the second quantum dot light-emitting layer 700 includes second quantum dots 701 and a second cross-linking structure 702.

[0066] The second cross-linking structure 702 forms a coordination connection with the second quantum dot 701 , and the second cross-linking structure 702 is arranged on a side of the second quantum dot 701 close to the electron transport layer 300 and a side of the second quantum dot 701 close to the hole transport layer 200 .

[0067] In an optional embodiment, the material of the first quantum dot 101 and the material of the second quantum dot 701 can be the same or different; the material of the first cross-linked structure 103 and the material of the second cross-linked structure 702 can be the same or different. Preferably, in order to reduce the preparation cost and simplify the process flow, the material of the first quantum dot 101 and the material of the second quantum dot 701 are the same; the material of the first cross-linked structure 103 and the material of the second cross-linked structure 702 are the same.

[0068] In the embodiment of the present application, by setting the second quantum dot light-emitting layer 700 between the first quantum dot light-emitting layer 100 and the electron transport layer 300, the flatness of the quantum dot light-emitting layer can be better guaranteed, and the leakage and other undesirable phenomena caused by the gaps between the first quantum dots 101 in the single-layer first quantum dot light-emitting layer 100 can be prevented, thereby further curbing the decline in luminous efficiency.

[0069] In an optional embodiment, the quantum dot light-emitting device also includes: a cathode 500 and an anode 400, the first quantum dot light-emitting layer 100 is arranged between the cathode 500 and the anode 400, the hole transport layer 200 is arranged between the first quantum dot light-emitting layer 100 and the anode 400, and the electron transport layer 300 is arranged between the first quantum dot light-emitting layer 100 and the cathode 500; a hole injection layer 600, and the hole injection layer 600 is arranged between the hole transport layer 200 and the anode 400.

[0070] In an optional embodiment, the quantum dot light-emitting device is a blue quantum dot light-emitting device, a red quantum dot light-emitting device or a green quantum dot light-emitting device, wherein the first quantum dot of the first quantum dot light-emitting layer of the blue quantum dot light-emitting device is a blue first quantum dot, the first quantum dot of the first quantum dot light-emitting layer of the red quantum dot light-emitting device is a red first quantum dot, and the first quantum dot of the first quantum dot light-emitting layer of the green quantum dot light-emitting device is a green first quantum dot. The second ligand and the first cross-linked structure material of the first quantum dot light-emitting layer of the blue quantum dot light-emitting device, the red quantum dot light-emitting device and the green quantum dot light-emitting device may be the same or different.

[0071] The present application provides a quantum dot light-emitting device and a preparation method thereof, and a display device, wherein the quantum dot light-emitting device comprises: a first quantum dot light-emitting layer; a hole transport layer and an electron transport layer, wherein the hole transport layer is arranged on one side of the first quantum dot light-emitting layer, and the electron transport layer is arranged on the side of the first quantum dot light-emitting layer away from the hole transport layer; wherein the first quantum dot light-emitting layer material comprises a first quantum dot, a first cross-linking structure, and a second ligand, wherein the first cross-linking structure and the second ligand respectively form a coordination connection with the first quantum dot, the first cross-linking structure is arranged on the side of the first quantum dot close to the electron transport layer, and the second ligand is arranged on the side of the first quantum dot close to the hole transport layer. The present application effectively balances the carrier concentration of the quantum dot light-emitting layer by setting the side of the first quantum dot light-emitting layer close to the electron transport layer as a first cross-linking structure that can reduce electron injection, and the side close to the hole transport layer as a second ligand that enhances hole injection, thereby achieving an improvement in the efficiency of the quantum dot light-emitting diode device.

[0072] Based on the same inventive concept, an embodiment of the present application provides a display device, which includes a plurality of quantum dot light-emitting devices as described in the embodiment of the present application.

[0073] In the embodiments of the present application, the display device may be a display or a product including a display. The display may be a flat panel display (Flat Panel Display, FPD), a micro display, etc. If the scene is divided according to whether the user can see the back of the display, the display may be a transparent display or an opaque display. It should be noted that the specific display device can be determined according to the actual situation, and the present application does not limit it here.

[0074] Based on the same inventive concept, an embodiment of the present application provides a method for preparing a quantum dot light-emitting device, the method comprising: providing an electron transport layer; forming a first quantum dot light-emitting layer on one side of the electron transport layer; forming a hole transport layer on the side of the first quantum dot light-emitting layer away from the electron transport layer; wherein the first quantum dot light-emitting layer material comprises a first quantum dot, a first cross-linking structure and a second ligand, the first cross-linking structure and the second ligand respectively form a coordination connection with the first quantum dot, the first cross-linking structure is arranged on a side of the first quantum dot close to the electron transport layer, and the second ligand is arranged on a side of the first quantum dot close to the hole transport layer.

[0075] In an optional embodiment, Figure 3 A schematic diagram of a method for preparing a quantum dot light-emitting device according to an embodiment of the present application is shown. Figure 3 As shown, first, a cathode 500 is formed, and an electron transport layer material is spin-coated on one side of the cathode 500, and annealing is performed at a preset temperature to form the electron transport layer 300; a first ligand 104 modification (including a cross-linking agent) is spin-coated on the side of the electron transport layer 300 away from the cathode 500; and a first quantum dot with a third ligand 105 is spin-coated on the side of the first ligand 104 away from the electron transport layer 300, so that the first ligand 104 and the third ligand 105 close to the first ligand 104 in the first quantum dot with the third ligand 105 undergo in-situ ligand exchange to form a transitional quantum dot layer (the exchanged third ligand will dissolve in the solvent, and in the subsequent rotation process, the solvent takes the exchanged third ligand out of the quantum dot light-emitting layer together).

[0076] Then, a mask is set, and the transition quantum dot layer is exposed and developed to crosslink the first ligand 104 in the transition quantum dot layer to form the first crosslinking structure 103; the second ligand 102 is spin-coated on the side of the transition quantum dot layer away from the electron transport layer 300, so that the second ligand 102 and the third ligand 105 in the transition quantum dot layer close to the second ligand 102 undergo in-situ ligand exchange to form the first quantum dot light-emitting layer 100. After the first quantum dot light-emitting layer 100 is formed, a hole transport layer 200, a hole injection layer 600 and an anode 400 are sequentially evaporated on the side of the first quantum dot light-emitting layer 100 away from the electron transport layer 300, and the quantum dot light-emitting device is packaged.

[0077] In an optional embodiment, in order to make the first end of the first ligand under illumination conditions successfully cross-linked as much as possible to form a cross-linked structure, the cross-linking agent provided in the embodiment of the present application is an excess cross-linking agent. By providing an excess of cross-linking agent, the first ligand close to one side of the electron transport layer can be avoided from being exchanged with the subsequent second ligand due to incomplete cross-linking, thereby avoiding the contact between the first ligand and the second ligand. Preferably, in order to further avoid the contact between the first ligand and the second ligand, after forming the first cross-linked structure 103, the first cross-linked structure is rinsed, for example, using PMA (propylene glycol methyl ether acetate) to rinse off the first ligand that has not been cross-linked, so as to avoid the contact between the first ligand and the second ligand.

[0078] Exemplarily, the first ligand is succinic acid mono[2-[(2-methyl-acryloyl)oxy]ethyl] ester, and the third ligand is an oleic acid ligand. An ITO patterned substrate is used as a cathode, and the ITO patterned substrate is sequentially cleaned with water, ethanol, and acetone, and blown dry with a nitrogen gun; a ZnO material is spin-coated on one side of the ITO patterned substrate, and annealed at a preset temperature to form the electron transport layer; a first ligand modification (containing a cross-linking agent) is spin-coated on the side of the electron transport layer away from the cathode; a first quantum dot with a third ligand (oleic acid ligand) is spin-coated on the side of the first ligand away from the electron transport layer, so that the first ligand and the oleic acid ligand close to the first ligand in the first quantum dot with oleic acid ligand undergo in-situ ligand exchange to form a transition quantum dot layer.

[0079] Subsequently, a mask plate is set to expose and develop the transition quantum dot layer so that the first ligand in the transition quantum dot layer is cross-linked to form the first cross-linked structure; the second ligand is spin-coated on the side of the transition quantum dot layer away from the electron transport layer so that the second ligand and the oleic acid ligand close to the second ligand in the transition quantum dot layer undergo in-situ ligand exchange to form the first quantum dot light-emitting layer; a hole transport layer, a hole injection layer and an Ag electrode (anode) are sequentially evaporated on the side of the first quantum dot light-emitting layer away from the electron transport layer, and the quantum dot light-emitting device is packaged.

[0080] In an optional embodiment, in order to improve the flatness of the quantum dot light-emitting layer and prevent the leakage problem of the single-layer quantum dot light-emitting layer, before the first ligand 104 is spin-coated on the side of the electron transport layer 300 away from the cathode 500 for modification, a second quantum dot light-emitting layer is first prepared. Figure 4 FIG. 1 shows a schematic flow chart of a method for preparing a quantum dot light-emitting device with a second quantum dot light-emitting layer according to an embodiment of the present application. Figure 4As shown, a second quantum dot (containing a cross-linking agent) with the first ligand 104 is spin-coated on one side of the electron transport layer 300. After exposure treatment, the first ligand of the second quantum dot is cross-linked under the action of light to form a second cross-linked structure 702, thereby obtaining a second quantum dot light-emitting layer; the first ligand 104 is spin-coated on the side of the second quantum dot light-emitting layer away from the electron transport layer 300 for modification; and a first quantum dot with a third ligand 105 is spin-coated on the side of the first ligand 104 away from the electron transport layer 300, so that the first ligand 104 and the third ligand 105 in the first quantum dot with the third ligand 105 close to the first ligand 104 undergo in-situ ligand exchange to form a transitional quantum dot layer.

[0081] Then, a mask plate is set to expose and develop the transition quantum dot layer so that the first ligand 104 in the transition quantum dot layer is cross-linked to form the first cross-linked structure 103; the second ligand 102 is spin-coated on the side of the transition quantum dot layer away from the electron transport layer 300, so that the second ligand 102 and the third ligand 105 in the transition quantum dot layer close to the second ligand 102 undergo in-situ ligand exchange to form the first quantum dot light-emitting layer 100; after the first quantum dot light-emitting layer 100 is formed, a hole transport layer 200, a hole injection layer 600 and an anode 400 are sequentially evaporated on the side of the first quantum dot light-emitting layer 100 away from the electron transport layer 300, and the quantum dot light-emitting device is packaged.

[0082] Exemplarily, the first ligand is succinic acid mono[2-[(2-methyl-acryloyl)oxy]ethyl] ester, and the third ligand is an oleic acid ligand. An ITO patterned substrate is used as a cathode, and the ITO patterned substrate is cleaned with water, ethanol, and acetone in sequence, and blown dry with a nitrogen gun; a ZnO material is spin-coated on one side of the ITO patterned substrate, and annealed at a preset temperature to form the electron transport layer; a second quantum dot (containing a crosslinking agent) with the first ligand is spin-coated on one side of the electron transport layer, and after exposure treatment, the first ligand of the second quantum dot is cross-linked under the action of light to form a second cross-linked structure, thereby obtaining a second quantum dot light-emitting layer; the first ligand modification (containing a crosslinking agent) is spin-coated on the side of the second quantum dot light-emitting layer away from the electron transport layer; a first quantum dot with a third ligand (oleic acid ligand) is spin-coated on the side of the first ligand away from the electron transport layer, so that the first ligand and the oleic acid ligand close to the first ligand in the first quantum dot with oleic acid ligand undergo in-situ ligand exchange to form a transitional quantum dot layer.

[0083] Subsequently, a mask plate is set to expose and develop the transition quantum dot layer so that the first ligand in the transition quantum dot layer is cross-linked to form the first cross-linked structure; the second ligand is spin-coated on the side of the transition quantum dot layer away from the electron transport layer so that the second ligand and the oleic acid ligand close to the second ligand in the transition quantum dot layer undergo in-situ ligand exchange to form the first quantum dot light-emitting layer; a hole transport layer, a hole injection layer and an Ag electrode (anode) are sequentially evaporated on the side of the first quantum dot light-emitting layer away from the electron transport layer, and the quantum dot light-emitting device is packaged.

[0084] In an optional embodiment, the quantum dot light-emitting device includes a first color quantum dot light-emitting device, a second color quantum dot light-emitting device and a third color quantum dot light-emitting device. The quantum dot light-emitting layer including the first color quantum dot light-emitting device, the second color quantum dot light-emitting device and the third color quantum dot light-emitting device is prepared as follows: spin coating a first ligand on one side of the electron transport layer; spin coating a first color quantum dot with a third ligand on a side of the first ligand away from the electron transport layer to form a first transition quantum dot layer; exposing and developing the first transition quantum dot layer to form the first cross-linked structure located in the first color sub-pixel region.

[0085] Subsequently, the first ligand is spin-coated on one side of the electron transport layer and the first transition quantum dot layer; the second color quantum dots with the third ligand are spin-coated on the side of the first ligand facing away from the electron transport layer to form a second transition quantum dot layer; the second transition quantum dot layer is exposed and developed to form the first cross-linked structure located in the second color sub-pixel area.

[0086] The first ligand is spin-coated on one side of the electron transport layer, the first transition quantum dot layer and the second transition quantum dot layer; a third color quantum dot with a third ligand is spin-coated on the side of the first ligand facing away from the electron transport layer to form a third transition quantum dot layer; the third transition quantum dot layer is exposed and developed to form the first cross-linked structure located in the third color sub-pixel area.

[0087] Finally, the second ligand is spin-coated on the side of the transition quantum dot layer away from the electron transport layer to form the first quantum dot light-emitting layer, and the transition quantum dot layer includes the first transition quantum dot layer, the second transition quantum dot layer and the third transition quantum dot layer.

[0088] In an optional implementation, the first color, the second color and the third color are red, green and blue. Figure 5 FIG. 1 shows a schematic flow chart of a method for preparing an RGB quantum dot light-emitting device according to an embodiment of the present application. Figure 5 As shown, the first ligand 104 is spin-coated on one side of the electron transport layer 300 for modification; the first red quantum dot ( ) with the third ligand 105 is spin-coated on the side of the first ligand 104 away from the electron transport layer 300. Figure 5 In the middle quantum dot R), the first ligand 104 and the third ligand 105 in the first red quantum dot with the third ligand 105 close to the first ligand 104 undergo in-situ ligand exchange to form a transitional red quantum dot layer.

[0089] Then, a first mask is set to expose the transitional red quantum dot layer to cross-link the first ligand 104 in the transitional red quantum dot layer to form the first cross-linked structure 103, and then a development process is performed to remove the first red quantum dots in the green and blue sub-pixels.

[0090] Then, the first ligand 104 is spin-coated for modification, and the third ligand on the first red quantum dot undergoes in-situ ligand exchange with the first ligand spin-coated; the first green quantum dot ( Figure 5 In the green quantum dot G), the first ligand 104 in the green and blue sub-pixels undergoes in-situ ligand exchange with the third ligand 105 in the first green quantum dot with the third ligand 105 close to the first ligand 104 to form a transitional green quantum dot layer.

[0091] Then, a second mask is set to expose the transitional green quantum dot layer to cross-link the first ligand 104 in the transitional green quantum dot layer to form the first cross-linked structure 103, and then a development process is performed to remove the first green quantum dots in the red and blue sub-pixels.

[0092] Then, the first ligand 104 is spin-coated for modification. At this time, the third ligand on the first red quantum dot and the third ligand on the first green quantum dot respectively undergo in-situ ligand exchange with the first ligand spin-coated. The first blue quantum dot ( Figure 5 In the blue sub-pixel, the first ligand 104 is placed in the middle quantum dot B), so that the first ligand 104 in the blue sub-pixel undergoes in-situ ligand exchange with the third ligand 105 in the first blue quantum dot with the third ligand 105 close to the first ligand 104 to form a transitional blue quantum dot layer.

[0093] Then, a third mask is set to expose the transitional blue quantum dot layer to cross-link the first ligand 104 in the transitional blue quantum dot layer to form the first cross-linked structure 103, and then a development process is performed to remove the first blue quantum dots in the red and green sub-pixels.

[0094] Finally, the second ligand 102 is spin-coated on the side of the transition quantum dot layer (including the transition red quantum dot layer, the transition blue quantum dot layer, and the transition green quantum dot layer) away from the electron transport layer 300, so that the second ligand 102 undergoes in-situ ligand exchange with the third ligand 105 in the transition quantum dot layer close to the second ligand 102 to form the first quantum dot light-emitting layer (including the first red quantum dot light-emitting layer, the first blue quantum dot light-emitting layer, and the first green quantum dot light-emitting layer); after the first quantum dot light-emitting layer is formed, a hole transport layer 200, a hole injection layer 600, and an anode 400 are sequentially evaporated on the side of the first quantum dot light-emitting layer away from the electron transport layer 300, and the quantum dot light-emitting device is packaged.

[0095] It should be noted that the above preparation method only schematically provides a method for preparing a quantum dot light-emitting device in a red-green-blue order. In the actual preparation method, the preparation order of quantum dots of different colors can be determined according to actual conditions, and this application does not limit it here.

[0096] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0097] Although the preferred embodiments of the present disclosure have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present disclosure.

[0098] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[0099] The above is a detailed introduction to a quantum dot light-emitting device and a preparation method and a display device provided by the present disclosure. Specific examples are used in this article to illustrate the principles and implementation methods of the present disclosure. The description of the above embodiments is only used to help understand the method and core ideas of the present disclosure. At the same time, for general technicians in this field, according to the ideas of the present disclosure, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present disclosure.

Claims

1. A quantum dot light-emitting device, characterized in that: include: a first quantum dot light-emitting layer; A hole transport layer and an electron transport layer, wherein the hole transport layer is arranged on one side of the first quantum dot light-emitting layer, and the electron transport layer is arranged on a side of the first quantum dot light-emitting layer away from the hole transport layer; Among them, the first quantum dot light-emitting layer material includes a first quantum dot, a first cross-linking structure and a second ligand, the first cross-linking structure and the second ligand respectively form a coordination connection with the first quantum dot, the first cross-linking structure is arranged on a side of the first quantum dot close to the electron transport layer, and the second ligand is arranged on a side of the first quantum dot close to the hole transport layer.

2. The quantum dot light-emitting device according to claim 1, characterized in that: The first cross-linked structure is a network structure formed by cross-linking the first ligand, wherein The first end of the first ligand is used for cross-linking to form the first cross-linking structure, the second end of the first ligand is used for forming a coordination connection with the first quantum dot, and the second end of the first ligand is provided with a coordination functional group.

3. The quantum dot light-emitting device according to claim 1, characterized in that: The first end of the second ligand is used for hole injection, the second end of the second ligand is used for forming a coordination connection with the first quantum dot, and the second end of the second ligand is provided with a coordination functional group.

4. The quantum dot light-emitting device according to claim 2, characterized in that: The first end of the first ligand includes at least one of the following structures: a double bond, a triple bond, an acrylate bond, and ethylene oxide.

5. The quantum dot light-emitting device according to claim 3, characterized in that: The first end of the second ligand includes at least one of the following structures: carbazole, triarylamine, triphenylamine and fluorene.

6. The quantum dot light-emitting device according to claim 2 or 3, characterized in that: The coordination functional group includes at least one of the following: a thiol group, a carboxyl group, an amino group, a polyamino group, a phosphorus oxygen group and a halogen ion.

7. The quantum dot light emitting device according to claim 2, characterized in that: The first ligand includes at least one of: mono[2-[(2-methyl-acryloyl)oxy]ethyl]succinate, mercaptopolyethylene glycol acrylate, 2-((2-(methacryloyloxy)ethyl)dimethylammonium)acetate, 5-hexenoic acid and 9-decenoic acid.

8. The quantum dot light emitting device according to claim 1, characterized in that: The quantum dot light emitting device further comprises: A second quantum dot light-emitting layer, wherein the second quantum dot light-emitting layer is disposed between the first quantum dot light-emitting layer and the electron transport layer, and the second quantum dot light-emitting layer material includes second quantum dots and a second cross-linked structure, wherein: The second cross-linking structure forms a coordination connection with the second quantum dot, and the second cross-linking structure is arranged on a side of the second quantum dot close to the electron transport layer and a side of the second quantum dot close to the hole transport layer.

9. The quantum dot light emitting device according to claim 8, characterized in that: The material of the first quantum dots is the same as that of the second quantum dots; the material of the first cross-linked structure is the same as that of the second cross-linked structure.

10. The quantum dot light emitting device according to claim 1, characterized in that: The quantum dot light emitting device further comprises: A cathode and an anode, wherein the first quantum dot light-emitting layer is disposed between the cathode and the anode, the hole transport layer is disposed between the first quantum dot light-emitting layer and the anode, and the electron transport layer is disposed between the first quantum dot light-emitting layer and the cathode; A hole injection layer is disposed between the hole transport layer and the anode.

11. A display device, characterized in that: The display device comprises a plurality of quantum dot light-emitting devices according to any one of claims 1 to 10.

12. A method for preparing a quantum dot light-emitting device, characterized in that: The method comprises: providing an electron transport layer; forming a first quantum dot light-emitting layer on one side of the electron transport layer; forming a hole transport layer on a side of the first quantum dot light-emitting layer away from the electron transport layer; Among them, the first quantum dot light-emitting layer material includes a first quantum dot, a first cross-linking structure and a second ligand, the first cross-linking structure and the second ligand respectively form a coordination connection with the first quantum dot, the first cross-linking structure is arranged on a side of the first quantum dot close to the electron transport layer, and the second ligand is arranged on a side of the first quantum dot close to the hole transport layer.

13. The method for preparing a quantum dot light-emitting device according to claim 12, characterized in that: The step of forming a first quantum dot light-emitting layer on one side of the electron transport layer comprises: Spin coating a first ligand on one side of the electron transport layer; Spin-coating a first quantum dot with a third ligand on a side of the first ligand away from the electron transport layer, so that the first ligand and the third ligand in the first quantum dot with the third ligand close to the first ligand undergo in-situ ligand exchange, forming a transition quantum dot layer; exposing and developing the transition quantum dot layer to cause the first ligand in the transition quantum dot layer to be cross-linked to form the first cross-linked structure; The second ligand is spin-coated on the side of the transition quantum dot layer away from the electron transport layer, so that the second ligand undergoes in-situ ligand exchange with the third ligand close to the second ligand in the transition quantum dot layer to form the first quantum dot light-emitting layer.

14. The method for preparing a quantum dot light-emitting device according to claim 13, characterized in that: The step of spin coating a first ligand on one side of the electron transport layer comprises: Spin coating the second quantum dots with the first ligand on one side of the electron transport layer, and obtaining a second quantum dot light-emitting layer through exposure treatment; The first ligand is spin-coated on a side of the second quantum dot light-emitting layer away from the electron transport layer.

15. The method for preparing a quantum dot light-emitting device according to claim 12, characterized in that: The step of forming a first quantum dot light-emitting layer on one side of the electron transport layer comprises: Spin-coating a first ligand on one side of the electron transport layer; spin-coating a first color quantum dot with a third ligand on a side of the first ligand away from the electron transport layer to form a first transition quantum dot layer; exposing and developing the first transition quantum dot layer to form the first cross-linked structure located in the first color sub-pixel region; Spin coating the first ligand on one side of the electron transport layer and the first transition quantum dot layer; spin coating the second color quantum dots with the third ligand on the side of the first ligand away from the electron transport layer to form a second transition quantum dot layer; and expose and develop the second transition quantum dot layer to form the first cross-linked structure located in the second color sub-pixel region; Spin coating the first ligand on one side of the electron transport layer, the first transition quantum dot layer and the second transition quantum dot layer; spin coating a third color quantum dot with a third ligand on the side of the first ligand away from the electron transport layer to form a third transition quantum dot layer; and exposing and developing the third transition quantum dot layer to form the first cross-linked structure located in the third color sub-pixel region; The second ligand is spin-coated on the side of the transition quantum dot layer away from the electron transport layer to form the first quantum dot light-emitting layer, and the transition quantum dot layer includes the first transition quantum dot layer, the second transition quantum dot layer and the third transition quantum dot layer.

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