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

Abstract

A quantum dot light-emitting device, a preparation method thereof, and a display device, the quantum dot light-emitting device comprising: a quantum dot light-emitting layer; a carrier transport layer located at least one side of the quantum dot light-emitting layer; a monomolecular layer located between the carrier transport layer and the quantum dot light-emitting layer; wherein the material of the monomolecular layer is configured to transform the molecular configuration from a cis configuration to a trans configuration under visible light irradiation or heating conditions, and transform the molecular configuration from the trans configuration to the cis configuration under ultraviolet light irradiation conditions, and the molecular chain length of the trans configuration is greater than that of the cis configuration. The quantum dot light-emitting device of the present embodiment can achieve the effect of weakening electron injection and the effect of inhibiting the quenching of quantum dots by surface defects of inorganic metal oxide materials under light irradiation or heating conditions.

Description

Technical Field

[0001] This disclosure relates to, but is not limited to, the field of display technology, and particularly to a quantum dot light-emitting device and its fabrication method, as well as a display device comprising the quantum dot light-emitting device. Background Technology

[0002] Quantum dots (QDs), as novel light-emitting materials, possess advantages such as high light purity, high quantum efficiency, tunable color emission, and long lifespan, making them a research hotspot for novel light-emitting diodes (LEDs). Therefore, quantum dot light-emitting diodes (QLEDs) using quantum dot materials as the light-emitting layer have become a major research direction for novel display devices.

[0003] Due to the inherent properties of quantum dot materials, they are generally fabricated using printing techniques or printing methods, which can effectively improve material utilization and is an effective way to prepare quantum dot films on a large area. When using inkjet printing to prepare quantum dot films, a pixel definition layer is pre-prepared before depositing each layer of the electroluminescent (EL) unit. The ink from each functional layer tends to climb on the bank, even reaching the top platform area of ​​the bank, significantly affecting the morphology and thickness uniformity of the quantum dot film. This has a significant impact on device performance and uniformity, thus affecting the mass production of QLEDs. This problem is particularly pronounced on high-resolution substrates. If the layers preceding the quantum dot layer, such as the hole injection layer (HIL) and hole transport layer (HTL), are also prepared using wet processes, they will also suffer from film inhomogeneity. The inhomogeneity of each layer accumulates, further affecting the uniformity of the quantum dot light-emitting layer and the final EL unit.

[0004] To address the issue of uneven film thickness during mass production, an inorganic electron transport layer can be used before the quantum dot (QD) luminescent layer, forming a smooth thin film through processes such as sputtering. However, regardless of whether an inorganic or organic electron transport layer is used, the high mobility of the electron transport (ET) material leads to excessive electron injection in the device, resulting in a large accumulation of electrons and affecting carrier balance. Furthermore, Auger recombination in the QD reduces the quantum efficiency (QY), ultimately impacting the device's luminescent efficiency. On the other hand, the surface of inorganic oxide electron transport layers often contains numerous defects, which quench the QD and also affect the device's luminescent efficiency. Summary of the Invention

[0005] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of protection of this application.

[0006] This disclosure provides a quantum dot light-emitting device, the quantum dot light-emitting device comprising:

[0007] Quantum dot light-emitting layer;

[0008] A carrier transport layer is located on at least one side of the quantum dot light-emitting layer;

[0009] A monolayer is located between the charge carrier transport layer and the quantum dot light-emitting layer;

[0010] The monolayer material is configured such that its molecular configuration changes from cis to trans under visible light irradiation or heating, and changes from trans to cis under ultraviolet light irradiation, with the trans molecular chain length being greater than that of the cis molecular chain length.

[0011] In an exemplary embodiment, the monolayer may be a self-assembled monolayer.

[0012] In an exemplary embodiment, the material of the monolayer may contain azo groups and At least one of the groups.

[0013] In an exemplary embodiment, the general structural formula of the monolayer material can be:

[0014]

[0015] In Formula I, A is a carbon atom or an ammonium ion. When A is an ammonium ion, Formula I also includes a halide anion, wherein the halide anion is selected from F. - Cl - ,Br - and I - At least one of the following; R1 and R2 in Formula I and Formula II are each independently selected from at least one of alkyl, -NH2, amino, alcohol amino, -NO2, -COOH and groups containing carbon-carbon double bonds.

[0016] In an exemplary embodiment, the material of the monolayer may be selected from any one or more of the following compounds:

[0017]

[0018] In an exemplary embodiment, the material of the monolayer may be a ligand, which coordinates with the quantum dots of the quantum dot luminescent layer.

[0019] In an exemplary embodiment, the ligand may contain an azo group and At least one of the groups.

[0020] In an exemplary embodiment, the general structural formula of the ligand can be:

[0021]

[0022] In Formula III, A is a carbon atom or an ammonium ion, and when A is an ammonium ion, Formula III also includes a halide anion, wherein the halide anion is selected from F. - Cl - ,Br - and I - At least one of the following: In formulas III and VI, one of R3 and R4 contains a coordinating group that can coordinate with the quantum dot, and the other of R3 and R4 is a free end, wherein the coordinating group is selected from any one or more of mercapto, hydroxyl, amino, carboxyl, ester, phosphin, and phosphoxy.

[0023] In an exemplary embodiment, the ligand may be selected from any one or more of the following:

[0024]

[0025]

[0026] Wherein, R3 is the coordinating group and R4 is the free end.

[0027] In an exemplary embodiment, the free end may contain a siloxane group.

[0028] In an exemplary embodiment, the monolayer material can be configured to change its molecular configuration from cis to trans under heating conditions of 80°C to 150°C.

[0029] In an exemplary embodiment, the charge carrier transport layer may be an electron transport layer and may include an inorganic metal oxide nanoparticle film or an inorganic metal oxide film, wherein the inorganic metal oxide may be selected from any one or more of ZnO, TiO2, SnO2 and ZrO2.

[0030] ZnO may include metal-doped ZnO, wherein the metal doped in the metal-doped ZnO may be selected from any one or more of Mg, Al, Zr and Y.

[0031] In an exemplary embodiment, the electron transport layer may include a red sub-pixel electron transport layer, a green sub-pixel electron transport layer, and a blue sub-pixel electron transport layer;

[0032] The red sub-pixel electron transport layer is an inorganic metal oxide nanoparticle thin film or an inorganic metal oxide thin film, wherein the inorganic metal oxide can be ZnO or ZnMgO.

[0033] The green sub-pixel electron transport layer is an inorganic metal oxide nanoparticle film or an inorganic metal oxide film, wherein the inorganic metal oxide can be ZnO or ZnMgO.

[0034] The blue sub-pixel electron transport layer is an inorganic metal oxide nanoparticle thin film or an inorganic metal oxide thin film, wherein the inorganic metal oxide can be ZnO or ZnMgO.

[0035] In an exemplary embodiment, the red sub-pixel electron transport layer, the green sub-pixel electron transport layer, and the blue sub-pixel electron transport layer may be ZnMgO nanoparticle thin films or ZnMgO thin films, and the weight percentage of Mg in the ZnMgO of the red sub-pixel electron transport layer is less than the weight percentage of Mg in the ZnMgO of the green sub-pixel electron transport layer, and the weight percentage of Mg in the ZnMgO of the green sub-pixel electron transport layer is less than the weight percentage of Mg in the ZnMgO of the blue sub-pixel electron transport layer.

[0036] In an exemplary embodiment, the charge carrier transport layer is a hole transport layer, and the material of the hole transport layer can be selected from any one or more of organic hole transport materials and inorganic metal oxide hole transport materials;

[0037] The organic hole transport material may include any one or more of poly(9,9-dioctylfluorene-CO-N-(4-butylphenyl)diphenylamine) (TFB), polyvinylcarbazole (PVK), N,N′-bis(3-methylphenyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine (TPD), and 4,4′-bis(9-carbazole)biphenyl (CBP);

[0038] The inorganic metal oxide hole transport material may include any one or more of NiO, NiO2, and V2O5.

[0039] In an exemplary embodiment, the hole transport layer may include a first hole transport layer close to the quantum dot light-emitting layer and a second hole transport layer away from the quantum dot light-emitting layer, wherein the material of the first hole transport layer is a first hole transport material and the material of the second hole transport layer is a second hole transport material.

[0040] -6.2eV≤│HOMO(A)│≤-5.5eV; -5.5eV≤│HOMO(B)│≤-5.0eV

[0041] Wherein, HOMO(A) is the highest occupied molecular orbital HOMO level of the first hole transport material, and HOMO(B) is the highest occupied molecular orbital HOMO level of the second hole transport material.

[0042] In an exemplary embodiment, the carrier transport layer may be located on both sides of the quantum dot light-emitting layer, with the carrier transport layer on one side of the quantum dot light-emitting layer being an electron transport layer and the carrier transport layer on the other side of the quantum dot light-emitting layer being a hole transport layer.

[0043] The electron transport layer may include an inorganic metal oxide nanoparticle film or an inorganic metal oxide film, wherein the inorganic metal oxide may be selected from any one or more of ZnO, TiO2, SnO2 and ZrO2; wherein ZnO may include metal-doped ZnO, wherein the metal doped in the metal-doped ZnO may be selected from any one or more of Mg, Al, Zr and Y.

[0044] The material of the hole transport layer can be selected from any one or more of organic hole transport materials and inorganic metal oxide hole transport materials; wherein, the organic hole transport material can include any one or more of poly(9,9-dioctylfluorene-CO-N-(4-butylphenyl)diphenylamine), polyvinylcarbazole, N,N′-bis(3-methylphenyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine and 4,4′-di(9-carbazole)biphenyl; the inorganic metal oxide hole transport material can include any one or more of NiO, NiO2 and V2O5.

[0045] In an exemplary embodiment, the electron transport layer may include a red sub-pixel electron transport layer, a green sub-pixel electron transport layer, and a blue sub-pixel electron transport layer;

[0046] The red sub-pixel electron transport layer is an inorganic metal oxide nanoparticle thin film or an inorganic metal oxide thin film, wherein the inorganic metal oxide can be ZnO or ZnMgO.

[0047] The green sub-pixel electron transport layer is an inorganic metal oxide nanoparticle film or an inorganic metal oxide film, wherein the inorganic metal oxide can be ZnO or ZnMgO.

[0048] The blue sub-pixel electron transport layer is an inorganic metal oxide nanoparticle thin film or an inorganic metal oxide thin film, wherein the inorganic metal oxide can be ZnO or ZnMgO.

[0049] In an exemplary embodiment, the red sub-pixel electron transport layer, the green sub-pixel electron transport layer, and the blue sub-pixel electron transport layer may be ZnMgO nanoparticle thin films or ZnMgO thin films, and the weight percentage of Mg in the ZnMgO of the red sub-pixel electron transport layer is less than the weight percentage of Mg in the ZnMgO of the green sub-pixel electron transport layer, and the weight percentage of Mg in the ZnMgO of the green sub-pixel electron transport layer is less than the weight percentage of Mg in the ZnMgO of the blue sub-pixel electron transport layer.

[0050] In an exemplary embodiment, the hole transport layer may include a first hole transport layer close to the quantum dot light-emitting layer and a second hole transport layer away from the quantum dot light-emitting layer, wherein the material of the first hole transport layer is a first hole transport material and the material of the second hole transport layer is a second hole transport material.

[0051] -6.2eV≤│HOMO(A)│≤-5.5eV; -5.5eV≤│HOMO(B)│≤-5.0eV

[0052] Wherein, HOMO(A) is the highest occupied molecular orbital HOMO level of the first hole transport material, and HOMO(B) is the highest occupied molecular orbital HOMO level of the second hole transport material.

[0053] In an exemplary embodiment, the first hole transport material may be selected from any one or two of 4,4',4”-tris(carbazole-9-yl)triphenylamine (TCTA) and 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline] (TAPC), and the second hole transport material may be selected from any one or two of 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB) and 4,4',4”-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA).

[0054] In an exemplary embodiment, the thickness of the hole transport layer can be from 20 nm to 60 nm, and the thickness of the first hole transport layer can be T. A 0nm < T A ≤10nm, the thickness of the second hole transport layer can be T B ,20nm≤T B ≤60nm.

[0055] This disclosure also provides a method for fabricating the quantum dot light-emitting device as described above, comprising:

[0056] Forming a quantum dot light-emitting layer;

[0057] Forming a carrier transport layer; and

[0058] A monolayer is formed between the charge carrier transport layer and the quantum dot light-emitting layer.

[0059] In an exemplary embodiment, the monolayer is a self-assembled monolayer, and the formation of the monolayer may include:

[0060] The monolayer material is dissolved in a solvent to form a solution containing the monolayer material;

[0061] The monolayer is formed by immersion film formation or spin coating of the solution containing the monolayer material.

[0062] In an exemplary embodiment, the temperature for immersion film formation can be room temperature, the immersion time for immersion film formation can be 20 min to 50 min, and the solvent for dissolving the monolayer material can be selected from any one or more of ethanol, diethyl ether, acetic acid, alkanes, N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO).

[0063] In an exemplary embodiment, the material of the monolayer is a ligand, and the preparation method may include:

[0064] Provides initial quantum dots containing oil-soluble ligands;

[0065] The oil-soluble ligands on the surface of the initial quantum dots are exchanged using the ligands to obtain quantum dots containing ligands;

[0066] The quantum dot containing the ligand is used to form the quantum dot luminescent layer and the monolayer.

[0067] In an exemplary embodiment, the step of using the ligand to perform ligand exchange on the oil-soluble ligands on the surface of the initial quantum dot to obtain quantum dots containing ligands may include:

[0068] The ligand is dissolved in an organic solvent to obtain a ligand solution;

[0069] The initial quantum dots are added to the ligand solution to obtain a ligand solution containing the initial quantum dots. The solution is stirred to allow the ligands to exchange ligands with the oil-soluble ligands on the surface of the initial quantum dots.

[0070] The solution after ligand exchange is added to a poor solvent containing the ligands, causing the quantum dots containing the ligands to precipitate and separate from the solution.

[0071] In an exemplary embodiment, the organic solvent may be selected from any one or more alcohol solvents, and the unsuitable solvent for the ligand may be water.

[0072] This disclosure also provides a display device, which includes a plurality of quantum dot light-emitting devices as described above.

[0073] The quantum dot light-emitting device of the exemplary embodiments of this disclosure includes a photoisomerizable self-assembled molecular material or a quantum dot material with photoisomerizable ligands forming a quantum dot light-emitting layer. Under light or heating conditions, it can reduce electron injection and suppress the quenching of quantum dots by surface defects of inorganic metal oxide materials.

[0074] After reading and understanding the accompanying diagrams and detailed descriptions, the other aspects can be understood. Attached Figure Description

[0075] The accompanying drawings are used to provide an understanding of the technical solutions of this disclosure and form part of the specification. They are used together with the embodiments of this disclosure to explain the technical solutions of this disclosure and do not constitute a limitation on the technical solutions of this disclosure.

[0076] Figure 1 A schematic diagram illustrating the isomerization reaction of a monolayer material in a quantum dot light-emitting device according to an exemplary embodiment of this disclosure;

[0077] Figure 2 The capacitance change at the interface between the electron transport layer and the quantum dot light-emitting layer in the quantum dot light-emitting device before and after the molecular configuration of the monolayer material of the quantum dot light-emitting device, which is an exemplary embodiment of the present disclosure, changes under light illumination.

[0078] Figure 3 The graph shows the molecular configuration transformation of the monolayer material of the inverted quantum dot light-emitting device as an exemplary embodiment of the present disclosure and the variation of the current of the quantum dot light-emitting device with the gate voltage under different illumination conditions.

[0079] Figure 4 This is a schematic diagram illustrating the change in molecular configuration of the monolayer material shown in Equation II;

[0080] Figure 5 This is a schematic diagram of the structure of an inverted QLED device according to an exemplary embodiment of the present disclosure;

[0081] Figure 6 This is a schematic diagram of the structure of an inverted QLED device according to another exemplary embodiment of the present disclosure;

[0082] Figure 7 This is a schematic diagram of the structure of an inverted QLED device, which is yet another exemplary embodiment of the present disclosure.

[0083] Figure 8 for Figure 5 A schematic diagram showing the electron transport layer configuration of an inverted QLED device;

[0084] Figure 9 for Figure 5 A schematic diagram of the hole transport layer configuration in the inverted QLED device shown.

[0085] Figure 10 A schematic diagram of the structure of a QLED device with an upright structure, which is an exemplary embodiment of this disclosure;

[0086] Figure 11 This is a schematic diagram of the structure of a QLED device with an upright structure, as shown in another exemplary embodiment of this disclosure.

[0087] Figure 12 This is a schematic diagram of the structure of a QLED device with an upright structure, which is another exemplary embodiment of this disclosure.

[0088] The symbols in the attached diagram have the following meanings:

[0089] 100 - Anode; 200 - Hole injection layer; 300 - Hole transport layer; 301 - First hole transport layer; 302 - Second hole transport layer; 400 - Quantum dot luminescent layer; 500 - Monolayer; 501 - First monolayer; 502 - Second monolayer; 600 - Electron transport layer; 601 - Red subpixel electron transport layer; 602 - Green subpixel electron transport layer; 603 - Blue subpixel electron transport layer; 700 - Cathode. Detailed Implementation

[0090] The embodiments described herein can be implemented in many different forms. Those skilled in the art will readily understand that the implementation methods and content can be varied in many ways without departing from the spirit and scope of this disclosure. Therefore, this disclosure should not be construed as limited to the contents described in the following embodiments. Unless otherwise specified, the embodiments and features described in this disclosure can be arbitrarily combined with each other.

[0091] In the accompanying drawings, the size of constituent elements, the thickness of layers, or areas may sometimes be exaggerated for clarity. Therefore, any implementation of this disclosure is not necessarily limited to the dimensions shown in the drawings, and the shapes and sizes of components in the drawings do not reflect true proportions. Furthermore, the drawings schematically illustrate ideal examples, and any implementation of this disclosure is not limited to the shapes or values ​​shown in the drawings.

[0092] The ordinal numbers such as "first" and "second" in this specification are used to avoid confusion among the constituent elements, not to limit the quantity.

[0093] In this specification, "film" and "layer" may be used interchangeably. For example, "quantum dot film" may sometimes be replaced with "quantum dot layer".

[0094] This disclosure provides a quantum dot light-emitting device, which includes:

[0095] Quantum dot light-emitting layer;

[0096] A carrier transport layer is located on at least one side of the quantum dot light-emitting layer;

[0097] A monolayer is located between the charge carrier transport layer and the quantum dot light-emitting layer;

[0098] The monolayer material is configured such that its molecular configuration changes from cis to trans under visible light irradiation or heating, and changes from trans to cis under ultraviolet light irradiation, with the trans molecular chain length being greater than that of the cis molecular chain length.

[0099] The quantum dot light-emitting device of this disclosure introduces a monolayer. The monolayer material undergoes an isomerization reaction under visible light irradiation or heating. After the isomerization reaction, the molecular configuration of the monolayer material changes from cis to trans configuration, the conjugated state of the molecules within the layer changes, and the molecular chain length changes. Therefore, the distance between the charge carrier transport layer and the quantum dot light-emitting layer can be adjusted.

[0100] The quantum dot light-emitting device of this disclosure can emit visible light and generate heat when in operation, inducing the monolayer material to undergo an isomerization reaction to form a trans configuration, increasing the chain length and increasing the distance between the charge carrier transport layer and the quantum dot light-emitting layer, thereby reducing electron injection and minimizing quantum dot quenching, and improving luminous efficiency.

[0101] In an exemplary embodiment, the monolayer may be a self-assembled monolayer.

[0102] Figure 1 This is a schematic diagram illustrating the isomerization reaction of a monolayer material in a quantum dot light-emitting device according to an exemplary embodiment of this disclosure. Figure 1As shown, when monolayer materials are irradiated with visible light (λ≥400nm) or heated, their molecular configuration changes from cis to trans. Since the molecular chain length of the trans configuration is longer than that of the cis configuration, the molecular configuration change can increase the distance between the charge carrier transport layer and the quantum dot light-emitting layer, thereby reducing electron injection and suppressing the quenching of QD by surface defects in the charge carrier transport layer of inorganic metal oxide materials. Under ultraviolet light (λ≥365nm), the molecular configuration of the self-assembled monolayer material changes from trans to cis again, and the molecular chain length decreases.

[0103] Figure 2 This invention discloses the capacitance change at the interface between the electron transport layer and the quantum dot light-emitting layer of a monolayer material in a quantum dot light-emitting device before and after the molecular configuration changes under illumination. It can be seen that when the molecular configuration of the monolayer material changes to the cis configuration under ultraviolet light (UV, in this document, light with wavelengths from 10 nm to 400 nm), the interface capacitance increases, and the ability to transport electrons becomes stronger; however, under visible light (Vis, in this document, light with wavelengths in the range of 400 nm to 700 nm), the interface capacitance decreases, and the ability to transport electrons deteriorates.

[0104] Figure 3 The molecular configuration transformation of the monolayer material of the inverted quantum dot light-emitting device, as an exemplary embodiment of this disclosure, and the current (I) of the quantum dot light-emitting device. d ) with gate voltage (V G The graph shows the changes under different illumination conditions. This characterizes the configurational changes of the monolayer by measuring the channel current of the quantum dot light-emitting device. The principle is that the molecular configuration of the monolayer material transforms under different illumination conditions, causing a change in the distance between the active layer and the gate insulating layer in the inverted quantum dot light-emitting device, thus resulting in a change in the channel current. It can be seen that when the molecular configuration of the monolayer material is cis, a dipole is formed within the molecule, and the conjugation between the upper and lower layers of molecules is enhanced, increasing the current of the quantum dot light-emitting device.

[0105] In an exemplary embodiment, the material of the monolayer may contain azo groups and At least one of the groups.

[0106] In an exemplary embodiment, the general structural formula of the monolayer material can be:

[0107]

[0108] In Formula I, A is a carbon atom or an ammonium ion. When A is an ammonium ion, Formula I also includes a halide anion, wherein the halide anion is selected from F. - Cl - ,Br - and I - At least one of the following; R1 and R2 in Formula I and Formula II are each independently selected from at least one of alkyl, -NH2, amino (e.g., monoalkylamino, dialkylamino), alcoholamino (e.g., -N(C2H4OH)2, -N(CH2OH)2, -NHC2H4OH), -NO2, -COOH and groups containing carbon-carbon double bonds (e.g., -CH=CH2), and there is no requirement for the carbon chain length of the alkyl group, for example, the carbon chain length of the alkyl group can be 4 to 8.

[0109] Figure 4 This is a schematic diagram showing the change in molecular configuration of the monolayer material represented by Equation II.

[0110] In an exemplary embodiment, the material of the monolayer may be selected from any one or more of the following compounds:

[0111]

[0112]

[0113] In an exemplary embodiment, the material of the monolayer may be a ligand, which coordinates with the quantum dots of the quantum dot luminescent layer.

[0114] In an exemplary embodiment, the ligand may contain an azo group and At least one of the groups.

[0115] In an exemplary embodiment, the general structural formula of the ligand can be:

[0116]

[0117] In Formula III, A is a carbon atom or an ammonium ion, and when A is an ammonium ion, Formula III also includes a halide anion, wherein the halide anion is selected from F. - Cl - ,Br - and I - At least one of the following: In formulas III and VI, one of R3 and R4 contains a coordinating group that can coordinate with the quantum dot, and the other of R3 and R4 is a free end, wherein the coordinating group is selected from any one or more of mercapto, hydroxyl, amino, carboxyl, ester, phosphin, and phosphoxy.

[0118] In an exemplary embodiment, the ligand may be selected from any one or more of the following:

[0119]

[0120] Wherein, R3 is the coordinating group and R4 is the free end.

[0121] In an exemplary embodiment, the free end may contain a siloxane group.

[0122] In an exemplary embodiment, the ligand may be:

[0123]

[0124] In an exemplary embodiment, the monolayer material can be configured to change its molecular configuration from cis to trans under heating conditions of 80°C to 150°C.

[0125] In an exemplary embodiment, the charge carrier transport layer may be an electron transport layer and may include an inorganic metal oxide nanoparticle film or an inorganic metal oxide film, wherein the inorganic metal oxide may be selected from any one or more of ZnO, TiO2, SnO2 and ZrO2.

[0126] ZnO may include metal-doped ZnO, wherein the metal doped in the metal-doped ZnO may be selected from any one or more of Mg, Al, Zr and Y.

[0127] In an exemplary embodiment, the electron transport layer may include a red sub-pixel electron transport layer, a green sub-pixel electron transport layer, and a blue sub-pixel electron transport layer;

[0128] The red sub-pixel electron transport layer is an inorganic metal oxide nanoparticle thin film or an inorganic metal oxide thin film, wherein the inorganic metal oxide can be ZnO or ZnMgO.

[0129] The green sub-pixel electron transport layer is an inorganic metal oxide nanoparticle film or an inorganic metal oxide film, wherein the inorganic metal oxide can be ZnO or ZnMgO.

[0130] The blue sub-pixel electron transport layer is an inorganic metal oxide nanoparticle thin film or an inorganic metal oxide thin film, wherein the inorganic metal oxide can be ZnO or ZnMgO.

[0131] In an exemplary embodiment, the red sub-pixel electron transport layer, the green sub-pixel electron transport layer, and the blue sub-pixel electron transport layer may be ZnMgO nanoparticle thin films or ZnMgO thin films, and the weight percentage of Mg in the ZnMgO of the red sub-pixel electron transport layer is less than the weight percentage of Mg in the ZnMgO of the green sub-pixel electron transport layer, and the weight percentage of Mg in the ZnMgO of the green sub-pixel electron transport layer is less than the weight percentage of Mg in the ZnMgO of the blue sub-pixel electron transport layer.

[0132] In an exemplary embodiment, the weight percentage of Mg in the ZnMgO of the red sub-pixel electron transport layer can be 1% to 5%, the weight percentage of Mg in the ZnMgO of the green sub-pixel electron transport layer can be 5% to 10%, and the weight percentage of Mg in the ZnMgO of the blue sub-pixel electron transport layer can be 10% to 20%.

[0133] In an exemplary embodiment,

[0134] The thickness of the red subpixel electron transport layer can be from 40nm to 300nm, for example, from 40nm to 80nm, or for example, 60nm;

[0135] The thickness of the green subpixel electron transport layer can be from 30nm to 300nm, for example, from 30nm to 80nm, or for example, 30nm, 40nm, 50nm or 80nm;

[0136] The thickness of the blue subpixel electron transport layer can be from 20nm to 300nm, for example, from 20nm to 40nm or from 40nm to 80nm.

[0137] In an exemplary embodiment, the carrier transport layer may be a hole transport layer, and the material of the hole transport layer may be selected from any one or more of organic hole transport materials and inorganic metal oxide hole transport materials;

[0138] The organic hole transport material may include any one or more of poly(9,9-dioctylfluorene-CO-N-(4-butylphenyl)diphenylamine) (TFB), polyvinylcarbazole (PVK), N,N′-bis(3-methylphenyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine (TPD), and 4,4′-bis(9-carbazole)biphenyl (CBP);

[0139] The inorganic metal oxide hole transport material may include any one or more of NiO, NiO2, and V2O5.

[0140] In an exemplary embodiment, the hole transport layer may include a first hole transport layer close to the quantum dot light-emitting layer and a second hole transport layer away from the quantum dot light-emitting layer, wherein the material of the first hole transport layer is a first hole transport material and the material of the second hole transport layer is a second hole transport material.

[0141] -6.2eV≤│HOMO(A)│≤-5.5eV; -5.5eV≤│HOMO(B)│≤-5.0eV

[0142] Wherein, HOMO(A) is the highest occupied molecular orbital HOMO level of the first hole transport material, and HOMO(B) is the highest occupied molecular orbital HOMO level of the second hole transport material.

[0143] In an exemplary embodiment, the first hole transport material may be selected from any one or two of 4,4',4”-tris(carbazole-9-yl)triphenylamine (TCTA) and 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline] (TAPC), and the second hole transport material may be selected from any one or two of 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB) and 4,4',4”-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA).

[0144] In an exemplary embodiment, the thickness of the hole transport layer can be from 20 nm to 60 nm, and the thickness of the first hole transport layer can be T. A 0nm < T A ≤10nm, the thickness of the second hole transport layer can be T B ,20nm≤T B ≤60nm; for example, T A It can be 5nm, T B It can be 30nm.

[0145] In an exemplary embodiment, the carrier transport layer may be located on both sides of the quantum dot light-emitting layer, with the carrier transport layer on one side of the quantum dot light-emitting layer being an electron transport layer and the carrier transport layer on the other side of the quantum dot light-emitting layer being a hole transport layer.

[0146] The electron transport layer may include an inorganic metal oxide nanoparticle film or an inorganic metal oxide film, wherein the inorganic metal oxide may be selected from any one or more of ZnO, TiO2, SnO2 and ZrO2; wherein ZnO may include metal-doped ZnO, wherein the metal doped in the metal-doped ZnO may be selected from any one or more of Mg, Al, Zr and Y.

[0147] The material of the hole transport layer can be selected from any one or more of organic hole transport materials and inorganic metal oxide hole transport materials; wherein, the organic hole transport material can include any one or more of poly(9,9-dioctylfluorene-CO-N-(4-butylphenyl)diphenylamine), polyvinylcarbazole, N,N′-bis(3-methylphenyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine and 4,4′-di(9-carbazole)biphenyl; the inorganic metal oxide hole transport material can include any one or more of NiO, NiO2 and V2O5.

[0148] In an exemplary embodiment, the electron transport layer may include a red sub-pixel electron transport layer, a green sub-pixel electron transport layer, and a blue sub-pixel electron transport layer;

[0149] The red sub-pixel electron transport layer is an inorganic metal oxide nanoparticle thin film or an inorganic metal oxide thin film, wherein the inorganic metal oxide can be ZnO or ZnMgO.

[0150] The green sub-pixel electron transport layer is an inorganic metal oxide nanoparticle film or an inorganic metal oxide film, wherein the inorganic metal oxide can be ZnO or ZnMgO.

[0151] The blue sub-pixel electron transport layer is an inorganic metal oxide nanoparticle thin film or an inorganic metal oxide thin film, wherein the inorganic metal oxide can be ZnO or ZnMgO.

[0152] In an exemplary embodiment, the red sub-pixel electron transport layer, the green sub-pixel electron transport layer, and the blue sub-pixel electron transport layer may be ZnMgO nanoparticle thin films or ZnMgO thin films, and the weight percentage of Mg in the ZnMgO of the red sub-pixel electron transport layer is less than the weight percentage of Mg in the ZnMgO of the green sub-pixel electron transport layer, and the weight percentage of Mg in the ZnMgO of the green sub-pixel electron transport layer is less than the weight percentage of Mg in the ZnMgO of the blue sub-pixel electron transport layer.

[0153] In an exemplary embodiment, the weight percentage of Mg in the ZnMgO of the red sub-pixel electron transport layer can be 1% to 5%, the weight percentage of Mg in the ZnMgO of the green sub-pixel electron transport layer can be 5% to 10%, and the weight percentage of Mg in the ZnMgO of the blue sub-pixel electron transport layer can be 10% to 20%.

[0154] In an exemplary embodiment,

[0155] The thickness of the red subpixel electron transport layer can be from 40nm to 300nm, for example, from 40nm to 80nm, or for example, 60nm;

[0156] The thickness of the green subpixel electron transport layer can be from 30nm to 300nm, for example, from 30nm to 80nm, or for example, 30nm, 40nm, 50nm or 80nm;

[0157] The thickness of the blue subpixel electron transport layer can be from 20nm to 300nm, for example, from 20nm to 40nm or from 40nm to 80nm.

[0158] In an exemplary embodiment, the hole transport layer may include a first hole transport layer close to the quantum dot light-emitting layer and a second hole transport layer away from the quantum dot light-emitting layer, wherein the material of the first hole transport layer is a first hole transport material and the material of the second hole transport layer is a second hole transport material.

[0159] -6.2eV≤│HOMO(A)│≤-5.5eV; -5.5eV≤│HOMO(B)│≤-5.0eV

[0160] Wherein, HOMO(A) is the highest occupied molecular orbital HOMO level of the first hole transport material, and HOMO(B) is the highest occupied molecular orbital HOMO level of the second hole transport material.

[0161] In an exemplary embodiment, the first hole transport material may be selected from any one or two of 4,4',4”-tris(carbazole-9-yl)triphenylamine (TCTA) and 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline] (TAPC), and the second hole transport material may be selected from any one or two of 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB) and 4,4',4”-tris(N-3-methylphenyl-N-phenylamino)triphenylamine (m-MTDATA).

[0162] In an exemplary embodiment, the thickness of the hole transport layer can be from 20 nm to 60 nm, and the thickness of the first hole transport layer can be T. A 0nm < T A ≤10nm, the thickness of the second hole transport layer can be T B ,20nm≤T B ≤60nm; for example, T A It can be 5nm, T B It can be 30nm.

[0163] In an exemplary embodiment, the quantum dot light-emitting device can be an upright structure or an inverted structure.

[0164] This disclosure also provides a method for fabricating the quantum dot light-emitting device as described above, comprising:

[0165] Forming a quantum dot light-emitting layer;

[0166] Forming a carrier transport layer; and

[0167] A monolayer is formed between the charge carrier transport layer and the quantum dot light-emitting layer.

[0168] In an exemplary embodiment, the monolayer is a self-assembled monolayer, and the formation of the monolayer may include:

[0169] The monolayer material is dissolved in a solvent to form a solution containing the monolayer material;

[0170] The monolayer is formed by immersion film formation or spin coating of the solution containing the monolayer material.

[0171] In an exemplary embodiment, the temperature for immersion film formation can be room temperature, for example, 20°C to 25°C; the immersion time for immersion film formation can be 20 min to 50 min; and the solvent for dissolving the monolayer material can be selected from any one or more of ethanol, diethyl ether, acetic acid, alkanes, N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO).

[0172] In an exemplary embodiment, the material of the monolayer is a ligand, and the preparation method may include:

[0173] Provides initial quantum dots containing oil-soluble ligands;

[0174] The oil-soluble ligands on the surface of the initial quantum dots are exchanged using the ligands to obtain quantum dots containing ligands;

[0175] The quantum dot containing the ligand is used to form the quantum dot luminescent layer and the monolayer.

[0176] In an exemplary embodiment, the step of using the ligand to perform ligand exchange on the oil-soluble ligands on the surface of the initial quantum dot to obtain quantum dots containing ligands may include:

[0177] The ligand is dissolved in an organic solvent to obtain a ligand solution;

[0178] The initial quantum dots are added to the ligand solution to obtain a ligand solution containing the initial quantum dots. The solution is stirred to allow the ligands to exchange ligands with the oil-soluble ligands on the surface of the initial quantum dots.

[0179] The solution after ligand exchange is added to a poor solvent containing the ligands, causing the quantum dots containing the ligands to precipitate and separate from the solution.

[0180] In an exemplary embodiment, the organic solvent may be selected from any one or more alcohol solvents, and the unsuitable solvent for the ligand may be water. In an exemplary embodiment, after the quantum dots containing the ligand are precipitated, they can be separated from the solution by centrifugation. For example, the precipitate can be separated from the supernatant by centrifugation, the supernatant can be removed, and the unsuitable solvent can be added again for centrifugation until the supernatant is clear. After removing the supernatant, the quantum dots containing the ligand can be obtained.

[0181] This disclosure also provides a quantum dot material, the quantum dot material comprising: a quantum dot and a ligand modifying the quantum dot, the ligand being coordinated with the quantum dot, the ligand being configured to change its molecular configuration from cis to trans under visible light irradiation or heating, and to change its molecular configuration from trans to cis under ultraviolet light irradiation, wherein the molecular chain length of the trans configuration is greater than that of the cis configuration.

[0182] The quantum dot material of this disclosure contains ligands that can undergo isomerization reactions under light or heating conditions. These ligands surround the quantum dots. When the quantum dot material of this disclosure is used to prepare the quantum dot light-emitting layer of a quantum dot light-emitting device, ligands are present between the quantum dots and the electron transport layer, as well as between the quantum dots and the hole transport layer. These ligands undergo isomerization reactions under visible light irradiation or heating conditions, changing their molecular configuration from cis to trans. This increases the spacing between the quantum dot transport layer and the electron transport layer, as well as between the quantum dot light-emitting layer and the hole transport layer, thereby reducing electron injection and minimizing quantum dot quenching, thus improving luminous efficiency.

[0183] In an exemplary embodiment, the ligand is configured to change its molecular configuration from cis to trans under heating conditions of 80°C to 150°C.

[0184] In an exemplary embodiment, the ligand may contain an azo group and At least one of the groups.

[0185] In an exemplary embodiment, the general structural formula of the ligand can be:

[0186]

[0187] In Formula III, A is a carbon atom or an ammonium ion, and when A is an ammonium ion, Formula III also includes a halide anion, wherein the halide anion is selected from F.- Cl - ,Br - and I - At least one of the following: In Formulas III and VI, one of R3 and R4 contains a coordinating group that can coordinate with the quantum dot, and the other of R3 and R4 is a free end. The coordinating group can be selected from any one or more of mercapto, hydroxyl, amino, amino, carboxyl, ester, phosphin, and phosphoxy groups. For example, the coordinating group can be selected from any one or more of mercapto, amino, and carboxyl groups. The free end can be any group, for example, it can be alkyl, -NH2, amino, alkanolamine, -NO2, -COOH, or a group containing a carbon-carbon double bond.

[0188] In an exemplary embodiment, the quantum dot material may be selected from any one or more of the following:

[0189]

[0190]

[0191] Wherein, R3 is the coordinating group and R4 is the free end.

[0192] In an exemplary embodiment, the free end may contain a siloxane group.

[0193] In an exemplary embodiment, the ligand may be:

[0194]

[0195] This disclosure also provides a method for preparing quantum dot materials as described above, including:

[0196] Provides initial quantum dots containing oil-soluble ligands;

[0197] The ligands are used to perform ligand exchange on the oil-soluble ligands on the surface of the initial quantum dots to obtain the quantum dot material.

[0198] In an exemplary embodiment, the step of using the ligand to perform ligand exchange on the oil-soluble ligands on the surface of the initial quantum dot to obtain the quantum dot material may include:

[0199] The ligand is dissolved in an organic solvent to obtain a ligand solution;

[0200] The initial quantum dots are added to the ligand solution to obtain a ligand solution containing the initial quantum dots. The solution is stirred to allow the ligands to exchange ligands with the oil-soluble ligands on the surface of the initial quantum dots.

[0201] The solution after ligand exchange is added to a poor solvent containing the ligands, causing the quantum dots containing the ligands to precipitate and separate from the solution, thus obtaining the quantum dot material.

[0202] In an exemplary embodiment, the organic solvent may be selected from any one or more alcohol solvents, and the unsuitable solvent for the ligand may be water.

[0203] In an exemplary embodiment, after the quantum dots containing ligands are precipitated, they can be separated from the solution by centrifugation. For example, the precipitate can be separated from the supernatant solution by centrifugation, the supernatant solution can be removed, and a poor solvent can be added again for centrifugation until the supernatant solution is clear. After removing the supernatant, the quantum dot material can be obtained.

[0204] This disclosure also provides a quantum dot light-emitting device, which includes a quantum dot light-emitting layer, the material of which is the quantum dot material as described above.

[0205] In an exemplary embodiment, the quantum dot light-emitting device may be an inverted structure.

[0206] Figure 5 This is a schematic diagram of the structure of an inverted QLED device, which is an exemplary embodiment of this disclosure. Figure 5 As shown, the inverted QLED device may include: a cathode 700, an electron transport layer 600 disposed on the cathode 700, a monolayer 500 disposed on the side of the electron transport layer 600 away from the cathode 700, a quantum dot light-emitting layer 400 disposed on the side of the monolayer 500 away from the cathode 700, a hole transport layer 300 disposed on the side of the quantum dot light-emitting layer 400 away from the cathode 700, a hole injection layer 200 disposed on the side of the hole transport layer 300 away from the cathode 700, and an anode 100 disposed on the side of the hole injection layer 200 away from the cathode 700.

[0207] Figure 6 This is a schematic diagram of the structure of an inverted QLED device according to another exemplary embodiment of this disclosure. Figure 6 As shown, the inverted QLED device may include: a cathode 700, an electron transport layer 600 disposed on the cathode 700, a quantum dot light-emitting layer 400 disposed on the side of the electron transport layer 600 away from the cathode 700, a monolayer 500 disposed on the side of the quantum dot light-emitting layer 400 away from the cathode 700, a hole transport layer 300 disposed on the side of the monolayer 500 away from the cathode 700, a hole injection layer 200 disposed on the side of the hole transport layer 300 away from the cathode 700, and an anode 100 disposed on the side of the hole injection layer 200 away from the cathode 700.

[0208] Figure 7This is a schematic diagram of the structure of an inverted QLED device, which is another exemplary embodiment of this disclosure. Figure 7 As shown, the inverted QLED device may include: a cathode 700, an electron transport layer 600 disposed on the cathode 700, a first monolayer 501 disposed on the side of the electron transport layer 600 away from the cathode 700, a quantum dot light-emitting layer 400 disposed on the side of the first monolayer 501 away from the cathode 700, a second monolayer 502 disposed on the side of the quantum dot light-emitting layer 400 away from the cathode 700, a hole transport layer 300 disposed on the side of the second monolayer 502 away from the cathode 700, a hole injection layer 200 disposed on the side of the hole transport layer 300 away from the cathode 700, and an anode 100 disposed on the side of the hole injection layer 200 away from the cathode 700.

[0209] In an exemplary embodiment, in an inverted QLED device,

[0210] The cathode 700 can be formed from a transparent conductive material or conductive polymer deposited on a substrate, or it can be a metal electrode such as Al or Ag. The transparent conductive material can be ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), FTO (F-doped Tin Oxide), etc., and the substrate can be a flexible substrate such as glass or polyester resin (Polyethylene Terephthalate, PET).

[0211] The electron transport layer 600 can be an inorganic metal oxide nanoparticle film or an inorganic metal oxide film, wherein the inorganic metal oxide is selected from any one or more of ZnO, TiO2, SnO2 and ZrO2; the inorganic metal oxide nanoparticle film can be obtained by depositing or spin-coating inorganic metal oxide nanoparticles by magnetron sputtering.

[0212] For example, the electron transport layer 600 can be a zinc oxide nanoparticle film or a zinc oxide film.

[0213] The electron transport layer 600 can also be made of ion-doped zinc oxide nanoparticles, such as Mg, Al, Zr or Y-doped zinc oxide nanoparticles, etc.

[0214] Figure 8 for Figure 5 The diagram shows the electron transport layer configuration of the inverted QLED device; as shown. Figure 8As shown, the electron transport layer 600 may include a red sub-pixel electron transport layer 601, a green sub-pixel electron transport layer 602, and a blue sub-pixel electron transport layer 603. The thickness of the electron transport layer of these three pixels can be set as needed, and can be between 20nm and 300nm, for example, between 30nm and 80nm.

[0215] For example, the red sub-pixel electron transport layer 601 is an inorganic metal oxide nanoparticle film or an inorganic metal oxide film, wherein the inorganic metal oxide is ZnO or ZnMgO, the weight percentage of Mg in ZnMgO is 1% to 5%, and the thickness of the red sub-pixel electron transport layer 601 can be 40nm to 300nm, for example, 40nm to 80nm, or for example, 60nm.

[0216] The green sub-pixel electron transport layer 602 is an inorganic metal oxide nanoparticle thin film or an inorganic metal oxide thin film, wherein the inorganic metal oxide is ZnO or ZnMgO, and the weight percentage of Mg in ZnMgO is 5% to 10%. The thickness of the green sub-pixel electron transport layer 602 can be 30nm to 300nm, for example, 30nm to 80nm, or for example, 30nm, 40nm, 50nm or 80nm.

[0217] The blue sub-pixel electron transport layer 603 is an inorganic metal oxide nanoparticle thin film or an inorganic metal oxide thin film, wherein the inorganic metal oxide is ZnO or ZnMgO, the weight percentage of Mg in ZnMgO is 10% to 20%, and the thickness of the blue sub-pixel electron transport layer 603 can be 20nm to 300nm, for example, 20nm to 40nm or 40nm to 80nm.

[0218] The quantum dot luminescent layer 400 can be prepared by spin coating, vapor deposition, inkjet printing, or electro-spraying. The quantum dots used to prepare the quantum dot luminescent layer can be selected from any one or more of CdS, CdSe, ZnSe, InP, PbS, CsPbCl3, CsPbBr3, CsPhI3, CdS / ZnS, CdSe / ZnS, ZnSe, ZnTeSe, ZnSe / ZnS, ZnTeSe / ZnS, InP / ZnS, PbS / ZnS, CsPbCl3 / ZnS, CsPbBr3 / ZnS, and CsPhI3 / ZnS. The thickness of the quantum dot luminescent layer 400 can be from 20 nm to 50 nm, for example, 30 nm or 40 nm.

[0219] The material of the hole transport layer 300 can be selected from any one or more of organic hole transport materials and inorganic metal oxide hole transport materials; the organic hole transport materials may include poly(9,9-dioctylfluorene-CO-N-(4-butylphenyl)diphenylamine) (TFB), polyvinylcarbazole (PVK), N,N′-bis(3-methylphenyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine (TPD) and 4,4'-di(9-carbazole)biphenyl (CBP); the inorganic metal oxide hole transport materials may include NiO, NiO2 and V2O5;

[0220] The hole transport layer 300 can be a single layer formed of one material or a composite layer formed by stacking multiple materials. Figure 9 for Figure 5 The diagram shows the hole transport layer configuration of the inverted QLED device; as shown. Figure 9 As shown, the hole transport layer 200 may include a first hole transport layer 301 close to the quantum dot light-emitting layer and a second hole transport layer 302 far from the quantum dot light-emitting layer. The material of the first hole transport layer 301 is a first hole transport material, and the material of the second hole transport layer 302 is a second hole transport material.

[0221] -6.2eV≤│HOMO(A)│≤-5.5eV; -5.5eV≤│HOMO(B)│≤-5.0eV

[0222] Wherein, HOMO(A) is the highest occupied molecular orbital HOMO level of the first hole transport material, and HOMO(B) is the highest occupied molecular orbital HOMO level of the second hole transport material.

[0223] The thickness of the hole transport layer can be from 20nm to 60nm, for example, from 25nm to 35nm; the thickness of the first hole transport layer 301 can be T A 0nm < T A ≤10nm, the thickness of the second hole transport layer 302 can be T B ,20nm≤T B ≤60nm; for example, T A It can be 5nm, T B It can be 30nm.

[0224] The hole injection layer 200 can be made of materials such as PEDOT:PSS (poly(3,4-ethylenedioxythiophene) / polystyrene sulfonate), HAT-CN (2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazabenzophenanthrene), etc.; or it can be an inorganic metal oxide or sulfide material such as NiO, MoO3, WoO3, V2O5, CuO, CuS, CuSCN, Cu:NiO, etc.; it can be prepared by spin coating, vapor deposition or inkjet printing, etc.; the thickness of the hole injection layer 200 can be 3nm to 10nm, for example, it can be 3nm, 5nm, 7nm or 10nm;

[0225] The anode 100 can be prepared by vapor deposition or sputtering, and can be a metal (e.g., Al, Ag, etc.) or an IZO film; the thickness can be from 10 nm to 100 nm.

[0226] In an exemplary embodiment, the quantum dot light-emitting device can be an upright structure.

[0227] Figure 10 This is a schematic diagram of the structure of a QLED device with an upright structure, which is an exemplary embodiment of this disclosure. Figure 10 As shown, the upright QLED device may include: an anode 100, a hole injection layer 200 disposed on the anode 100, a hole transport layer 300 disposed on the side of the hole injection layer 200 away from the anode 100, a monolayer 500 disposed on the side of the hole transport layer 300 away from the anode 100, a quantum dot light-emitting layer 400 disposed on the side of the monolayer 500 away from the anode 100, an electron transport layer 600 disposed on the side of the quantum dot light-emitting layer 400 away from the anode 100, and a cathode 700 disposed on the side of the electron transport layer 600 away from the anode 100.

[0228] Figure 11 This is a schematic diagram of the structure of a QLED device with an upright configuration, as shown in another exemplary embodiment of this disclosure. Figure 11 As shown, the upright QLED device may include: an anode 100, a hole injection layer 200 disposed on the anode 100, a hole transport layer 300 disposed on the side of the hole injection layer 200 away from the anode 100, a quantum dot light-emitting layer 400 disposed on the side of the hole transport layer 300 away from the anode 100, a monolayer 500 disposed on the side of the quantum dot light-emitting layer 400 away from the anode 100, an electron transport layer 600 disposed on the side of the monolayer 500 away from the anode 100, and a cathode 700 disposed on the side of the electron transport layer 600 away from the anode 100.

[0229] Figure 12 This is a schematic diagram of the structure of a QLED device with an upright configuration, which is yet another exemplary embodiment of this disclosure. Figure 12As shown, the upright QLED device may include: an anode 100, a hole injection layer 200 disposed on the anode 100, a hole transport layer 300 disposed on the side of the hole injection layer 200 away from the anode 100, a first monolayer 501 disposed on the side of the hole transport layer 300 away from the anode 100, a quantum dot light-emitting layer 400 disposed on the side of the first monolayer 501 away from the anode 100, a second monolayer 502 disposed on the side of the quantum dot light-emitting layer 400 away from the anode 100, an electron transport layer 600 disposed on the side of the second monolayer 502 away from the anode 100, and a cathode 700 disposed on the side of the electron transport layer 600 away from the anode 100.

[0230] In an exemplary embodiment, in a QLED device with an upright structure,

[0231] The anode 100 can be formed from a transparent conductive material or conductive polymer deposited on a substrate, or it can be a metal electrode such as Al or Ag. The transparent conductive material can be ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), FTO (F-doped Tin Oxide), etc., and the substrate can be a flexible substrate such as glass or polyester resin (Polyethylene Terephthalate, PET).

[0232] The cathode 700 can be prepared by vapor deposition or sputtering, and can be a metal (e.g., Al, Ag, etc.) or an IZO film; the thickness can be from 10 nm to 100 nm.

[0233] The hole injection layer 200, hole transport layer 300, quantum dot light-emitting layer 400, and electron transport layer 600 can be prepared using the same materials and methods as those used in inverted QLED devices.

[0234] This disclosure also provides a display device, which includes a plurality of quantum dot light-emitting devices as described above.

[0235] The display device can be any product or component with display function, such as a mobile phone, tablet computer, television, monitor, laptop computer, digital photo frame, navigator, in-vehicle display, smartwatch, or smart bracelet.

[0236] An exemplary embodiment of this disclosure provides a method having, as follows Figure 5 The inverted quantum dot light-emitting device shown is fabricated using the following methods:

[0237] (1) Deposit a first electrode (cathode) on a substrate, wherein the substrate may be a flexible substrate such as glass or PET, and the first electrode may be a transparent conductive material such as ITO, FTO or conductive polymer, or an opaque metal electrode such as Al or Ag.

[0238] (2) ZnO or ZnO nanoparticles doped with Mg, Al, Zr, Y, etc., are deposited on the first electrode by magnetron sputtering (or ZnO nanoparticles can be directly spin-coated) to form a ZnO nanoparticle thin film as an electron transport layer; the electron transport layer may include a red sub-pixel electron transport layer, a green sub-pixel electron transport layer, and a blue sub-pixel electron transport layer. The thickness of the electron transport layer of these three pixels can be set as needed, and can be between 20nm and 300nm, for example, between 30nm and 80nm; for example, the red sub-pixel electron transport layer is a ZnO or ZnMgO nanoparticle thin film, the weight percentage of Mg in ZnMgO is 1% to 5%, and the thickness of the red sub-pixel electron transport layer is 40nm to... The thickness of the green sub-pixel electron transport layer is 300nm, for example, it can be 40nm to 80nm, or even 60nm; the green sub-pixel electron transport layer is a ZnO or ZnMgO nanoparticle film, the weight percentage of Mg in ZnMgO is 5% to 10%, and the thickness of the green sub-pixel electron transport layer is 30nm to 300nm, for example, it can be 30nm to 80nm, or even 30nm, 40nm, 50nm, or 80nm; the blue sub-pixel electron transport layer is a ZnO or ZnMgO nanoparticle film, the weight percentage of Mg in ZnMgO is 10% to 20%, and the thickness of the blue sub-pixel electron transport layer is 20nm to 300nm, for example, the thickness is 20nm to 40nm or 40nm to 80nm.

[0239] (3) Preparation of self-assembled monolayers on the electron transport layer: The substrate with the completed ZnO nanoparticle film is immersed in a solution containing self-assembled monolayer material to form SAMs; wherein, the solution containing self-assembled monolayer material is formed by self-assembled monolayer material and solvent, and the solvent can be selected from any one or more of ethanol, diethyl ether, and acetic acid. When the self-assembled monolayer material contains alkyl groups, the solvent can be selected from any one or more of ethanol, diethyl ether, acetic acid, alkanes (e.g., cyclohexane), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO); the immersion time of the substrate in the solution containing self-assembled monolayer material can be 20 min to 50 min, for example, 30 min; in addition, SAMs can also be formed by spin coating;

[0240] The self-assembled monolayer material is configured such that its molecular configuration changes from cis to trans under visible light irradiation or heating, and from trans to cis under ultraviolet light irradiation, with the trans molecular chain length being greater than that of the cis molecular chain length; the heating temperature can be from 80°C to 150°C; the general structural formula of the self-assembled monolayer material can be:

[0241]

[0242] In Formula I, A is a carbon atom or an ammonium ion. When A is an ammonium ion, Formula I also includes a halide anion, wherein the halide anion is selected from F. - Cl - ,Br - and I - At least one of the following; R1 and R2 in Formula I and Formula II are each independently selected from at least one of alkyl, -NH2, amino (e.g., monoalkylamino, dialkylamino), alcoholamino (e.g., -N(C2H4OH)2, -N(CH2OH)2, -NHC2H4OH), -NO2, -COOH and a group containing a carbon-carbon double bond (e.g., -CH=CH2), and there is no requirement for the carbon chain length of the alkyl group, for example, the carbon chain length of the alkyl group can be 4 to 8;

[0243] For example, the material of the self-assembled monolayer is selected from any one or more of the following compounds:

[0244]

[0245]

[0246] (4) Quantum dot light-emitting layer on self-assembled monolayer: Red quantum dot light-emitting layer, green quantum dot light-emitting layer and blue quantum dot light-emitting layer are prepared sequentially on the self-assembled monolayer corresponding to the red sub-pixel electron transport layer, green sub-pixel electron transport layer and blue sub-pixel electron transport layer by inkjet printing or photolithography. The thickness of the three quantum dot light-emitting layers can be in the range of 20nm to 50nm, for example, 30nm or 40nm.

[0247] (5) Sequentially deposit a hole transport layer and a hole injection layer on the quantum dot layer.

[0248] The hole transport layer can be made of organic hole transport materials, such as TFB, PVK, TPD, CBP, etc., or inorganic metal oxides, such as NiO, NiO2, and V2O5. The hole transport layer can be a single layer formed by one material or a composite layer formed by stacking multiple materials. For example, the hole transport layer can include a first hole transport layer close to the quantum dot light-emitting layer and a second hole transport layer far from the quantum dot light-emitting layer. The material of the first hole transport layer is a first hole transport material with -6.2eV≤│HOMO(A)│≤-5.5eV; the material of the second hole transport layer is a second hole transport material with -5.5eV≤│HOMO(B)│≤-5.0eV.

[0249] The thickness of the hole transport layer can be from 20nm to 60nm, for example, from 25nm to 35nm; the thickness of the first hole transport layer can be T. A 0nm < T A ≤10nm, the thickness of the second hole transport layer can be T B 20nm≤TB≤60nm; for example, T A It can be 5nm, T B It can be 30nm;

[0250] The material of the hole injection layer can be PEDOT:PSS, HAT-CN, etc.; or it can be an inorganic metal oxide or sulfide material such as NiO, MoO3, WoO3, V2O5, CuO, CuS, CuSCN, Cu:NiO, etc.; and it can be prepared by spin coating, vapor deposition or inkjet printing.

[0251] The thickness of the hole injection layer can be from 3nm to 10nm, for example, it can be 3nm, 5nm, 7nm or 10nm;

[0252] (6) Prepare a second electrode (anode) on the hole injection layer: The second electrode can be metal such as Al or Ag, or IZO film can be deposited by magnetron sputtering, and its thickness can be 10 nm to 100 nm.

[0253] An exemplary embodiment of this disclosure provides a method having, as follows Figure 7 The inverted quantum dot light-emitting device shown is fabricated using the following methods:

[0254] (1) Deposit a first electrode (cathode) on a substrate, wherein the substrate may be a flexible substrate such as glass or PET, and the first electrode may be a transparent conductive material such as ITO, FTO or conductive polymer, or an opaque metal electrode such as Al or Ag.

[0255] (2) ZnO or ZnO nanoparticles doped with Mg, Al, Zr, Y, etc., are deposited on the first electrode by magnetron sputtering (or ZnO nanoparticles can be directly spin-coated) to form a ZnO nanoparticle thin film as an electron transport layer; the electron transport layer may include a red sub-pixel electron transport layer, a green sub-pixel electron transport layer, and a blue sub-pixel electron transport layer. The thickness of the electron transport layer of these three pixels can be set as needed, and can be between 20nm and 300nm, for example, between 30nm and 80nm; for example, the red sub-pixel electron transport layer is a ZnO or ZnMgO nanoparticle thin film, the weight percentage of Mg in ZnMgO is 1% to 5%, and the thickness of the red sub-pixel electron transport layer is 40nm to... The thickness of the green sub-pixel electron transport layer is 300nm, for example, it can be 40nm to 80nm, or even 60nm; the green sub-pixel electron transport layer is a ZnO or ZnMgO nanoparticle film, the weight percentage of Mg in ZnMgO is 5% to 10%, and the thickness of the green sub-pixel electron transport layer is 30nm to 300nm, for example, it can be 30nm to 80nm, or even 30nm, 40nm, 50nm, or 80nm; the blue sub-pixel electron transport layer is a ZnO or ZnMgO nanoparticle film, the weight percentage of Mg in ZnMgO is 10% to 20%, and the thickness of the blue sub-pixel electron transport layer is 20nm to 300nm, for example, the thickness is 20nm to 40nm or 40nm to 80nm.

[0256] (3) A red quantum dot light-emitting layer with a single molecular layer, a green quantum dot light-emitting layer with a single molecular layer, and a blue quantum dot light-emitting layer with a single molecular layer are prepared sequentially on the red sub-pixel electron transport layer, the green sub-pixel electron transport layer, and the blue sub-pixel electron transport layer by means of inkjet printing or photolithography. The thickness of the three quantum dot light-emitting layers can be in the range of 20nm to 50nm, for example, it can be 30nm or 40nm.

[0257] In this process, the quantum dots in the quantum dot luminescent layer contain ligands, so the ligands form a monolayer during the formation of the quantum dot luminescent layer. The ligands are configured such that their molecular configuration changes from cis to trans under visible light irradiation or heating, and from trans to cis under ultraviolet light irradiation. The molecular chain length of the trans configuration is longer than that of the cis configuration. The heating temperature can be from 80°C to 150°C.

[0258] The general structural formula of the ligand can be:

[0259]

[0260] In Formula III, A is a carbon atom or an ammonium ion, and when A is an ammonium ion, Formula III also includes a halide anion, wherein the halide anion is selected from F. - Cl - ,Br - and I - At least one of the following: In Formulas III and VI, one of R3 and R4 contains a coordinating group that can coordinate with the quantum dot, and the other of R3 and R4 is a free end. The coordinating group is selected from any one or more of mercapto, hydroxyl, amino, amino, carboxyl, ester, phosphin, and phosphoxy groups. For example, the coordinating group can be selected from any one or more of mercapto, amino, and carboxyl groups. The free end may contain a siloxane group. The free end can be any group, for example, it can be an alkyl group, -NH2, amino, alkanolamine, -NO2, -COOH, or a group containing a carbon-carbon double bond.

[0261] The quantum dots containing ligands may be selected from any one or more of the following:

[0262]

[0263]

[0264] The ligand-containing quantum dots can be prepared by the following method: providing initial quantum dots containing oil-soluble ligands (e.g., oleic acid); dissolving the ligands in an organic solvent (e.g., any one or more alcohol solvents) to obtain a ligand solution; adding the initial quantum dots to the ligand solution to obtain a ligand solution containing the initial quantum dots; stirring to allow the ligands to exchange with the oil-soluble ligands on the surface of the initial quantum dots; adding the solution after ligand exchange to a poor solvent for the ligands (e.g., deionized water) to precipitate the ligand-containing quantum dots; separating the precipitate from the supernatant by centrifugation; removing the supernatant and adding the poor solvent again for centrifugation until the supernatant is clear; removing the supernatant to obtain the ligand-containing quantum dots.

[0265] (4) Deposit hole transport layer and hole injection layer sequentially on a monolayer far from electron transport layer;

[0266] (5) Fabricate a second electrode (anode) on the hole injection layer: The second electrode can be metal such as Al or Ag, or IZO film can be deposited by magnetron sputtering, and its thickness can be 10 nm to 100 nm.

[0267] An exemplary embodiment of this disclosure provides a method having, as follows Figure 10 The quantum dot light-emitting device with the upright structure shown is fabricated by the following methods:

[0268] (1) Deposit a first electrode (anode) on a substrate, wherein the substrate may be a flexible substrate such as glass or PET, and the first electrode may be a transparent conductive material such as ITO, FTO or conductive polymer, or an opaque metal electrode such as Al or Ag.

[0269] (2) A hole injection layer and a hole transport layer are sequentially fabricated on the first electrode:

[0270] The hole injection layer can be made of materials such as PEDOT:PSS, HAT-CN, etc.; or it can be inorganic metal oxides or sulfide materials such as NiO, MoO3, WoO3, V2O5, CuO, CuS, CuSCN, Cu:NiO, etc.; it can be prepared by spin coating, vapor deposition or inkjet printing, etc.; the thickness of the hole injection layer can be 3nm to 7nm, for example, it can be 5nm.

[0271] The hole transport layer can be made of organic hole transport materials, such as TFB, PVK, TPD, CBP, etc., or inorganic metal oxides, such as NiO, NiO2, and V2O5. The hole transport layer can be a single layer formed by one material or a composite layer formed by stacking multiple materials. For example, the hole transport layer can include a first hole transport layer close to the quantum dot light-emitting layer and a second hole transport layer far from the quantum dot light-emitting layer. The material of the first hole transport layer is a first hole transport material with -6.2eV≤│HOMO(A)│≤-5.5eV; the material of the second hole transport layer is a second hole transport material with -5.5eV≤│HOMO(B)│≤-5.0eV.

[0272] The thickness of the hole transport layer can be from 20nm to 60nm, for example, from 25nm to 35nm; the thickness of the first hole transport layer can be T. A 0nm < T A ≤10nm, the thickness of the second hole transport layer can be T B ,20nm≤T B ≤60nm; for example, T A It can be 5nm, T B It can be 30nm;

[0273] (3) Preparation of self-assembled monolayers on the hole transport layer: The substrate with the hole transport layer prepared above is immersed in a solution containing self-assembled monolayer material to form SAMs; wherein, the solution containing self-assembled monolayer material is formed by self-assembled monolayer material and solvent, and the solvent can be selected from any one or more of ethanol, diethyl ether, and acetic acid. When the self-assembled monolayer material contains alkyl groups, the solvent can be selected from any one or more of ethanol, diethyl ether, acetic acid, alkanes (e.g., cyclohexane), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO); the immersion time of the substrate in the solution containing self-assembled monolayer material can be 20 min to 50 min, for example 30 min; in addition, SAMs can also be formed by spin coating;

[0274] The self-assembled monolayer material is configured such that its molecular configuration changes from cis to trans under visible light irradiation or heating, and from trans to cis under ultraviolet light irradiation, with the trans molecular chain length being greater than that of the cis molecular chain length; the heating temperature can be from 80°C to 150°C; the general structural formula of the self-assembled monolayer material can be:

[0275]

[0276] In Formula I, A is a carbon atom or an ammonium ion. When A is an ammonium ion, Formula I also includes a halide anion, wherein the halide anion is selected from F. - Cl - ,Br - and I - At least one of the following; R1 and R2 in Formula I and Formula II are each independently selected from at least one of alkyl, -NH2, amino (e.g., monoalkylamino, dialkylamino), alcoholamino (e.g., -N(C2H4OH)2, -N(CH2OH)2, -NHC2H4OH), -NO2, -COOH and a group containing a carbon-carbon double bond (e.g., -CH=CH2), and there is no requirement for the carbon chain length of the alkyl group, for example, the carbon chain length of the alkyl group can be 4 to 8;

[0277] For example, the material of the self-assembled monolayer is selected from any one or more of the following compounds:

[0278]

[0279]

[0280] (4) A quantum dot light-emitting layer is prepared on the self-assembled monolayer: The quantum dot light-emitting layer may include a red quantum dot light-emitting layer, a green quantum dot light-emitting layer and a blue quantum dot light-emitting layer. The thickness of the three quantum dot light-emitting layers can be in the range of 20 nm to 50 nm and can be prepared by inkjet printing or photolithography.

[0281] (5) Fabrication of an electron transport layer on the quantum dot emitting layer: A red sub-pixel electron transport layer, a green sub-pixel electron transport layer, and a blue sub-pixel electron transport layer are sequentially fabricated on a red quantum dot emitting layer, a green quantum dot emitting layer, and a blue quantum dot emitting layer by magnetron sputtering or spin coating. The red sub-pixel electron transport layer is a ZnO or ZnMgO nanoparticle film, wherein the weight percentage of Mg in ZnMgO is 1% to 5%, and the thickness of the red sub-pixel electron transport layer is 40 nm to 300 nm, for example, 40 nm to 80 nm, or for example, 60 nm. The green sub-pixel electron transport layer is... The green sub-pixel electron transport layer is a ZnO or ZnMgO nanoparticle film, wherein the weight percentage of Mg in ZnMgO is 5% to 10%, and the thickness is 30 nm to 300 nm, for example, 30 nm to 80 nm, or 30 nm, 40 nm, 50 nm, or 80 nm; the blue sub-pixel electron transport layer is a ZnO or ZnMgO nanoparticle film, wherein the weight percentage of Mg in ZnMgO is 10% to 20%, and the thickness is 20 nm to 300 nm, for example, 20 nm to 40 nm or 40 nm to 80 nm.

[0282] (6) Fabricate a second electrode (cathode) on the electron transport layer: The second electrode can be metal such as Al or Ag, or IZO film can be deposited by magnetron sputtering, and its thickness can be 10 nm to 100 nm.

[0283] While the embodiments disclosed herein are as described above, the content is merely for the purpose of facilitating understanding of this disclosure and is not intended to limit this disclosure. Any person skilled in the art may make any modifications and changes to the form and details of the implementation without departing from the spirit and scope of this disclosure; however, the scope of patent protection of this application shall still be determined by the scope defined in the appended claims.

Claims

1. A quantum dot light-emitting device, characterized in that, include: Quantum dot light-emitting layer; A carrier transport layer is located on at least one side of the quantum dot light-emitting layer; A monolayer is located between the charge carrier transport layer and the quantum dot light-emitting layer; The monolayer material is configured such that its molecular configuration changes from cis to trans under visible light irradiation or heating, and changes from trans to cis under ultraviolet light irradiation, with the trans molecular chain length being greater than that of the cis molecular chain length. Wherein, the monolayer is a self-assembled monolayer; the material of the monolayer is selected from any one or more of the following compounds: 、 、 、 、 ； Alternatively, the material of the monolayer is a ligand, which coordinates with the quantum dots of the quantum dot emitting layer; the ligand is selected from any one or more of the following: 、 ； Wherein, R3 is a coordinating group and R4 is a free end. The coordinating group is selected from any one or more of mercapto, hydroxyl, amino, carboxyl, phosphinyl and phosphoxy groups, and the free end contains a siloxane group.

2. The quantum dot light-emitting device according to claim 1, characterized in that, The monolayer material is configured such that its molecular configuration changes from cis to trans under heating conditions from 80°C to 150°C.

3. The quantum dot light-emitting device according to claim 1, characterized in that, The charge carrier transport layer is an electron transport layer and includes an inorganic metal oxide nanoparticle film or an inorganic metal oxide film, wherein the inorganic metal oxide is selected from any one or more of ZnO, TiO2, SnO2 and ZrO2. ZnO includes metal-doped ZnO, wherein the metal doped in the metal-doped ZnO is selected from any one or more of Mg, Al, Zr and Y.

4. The quantum dot light-emitting device according to claim 3, characterized in that, The electron transport layer includes a red sub-pixel electron transport layer, a green sub-pixel electron transport layer, and a blue sub-pixel electron transport layer; The red sub-pixel electron transport layer is an inorganic metal oxide nanoparticle thin film or an inorganic metal oxide thin film, wherein the inorganic metal oxide is ZnO or ZnMgO. The green sub-pixel electron transport layer is an inorganic metal oxide nanoparticle thin film or an inorganic metal oxide thin film, wherein the inorganic metal oxide is ZnO or ZnMgO. The blue sub-pixel electron transport layer is an inorganic metal oxide nanoparticle thin film or an inorganic metal oxide thin film, wherein the inorganic metal oxide is ZnO or ZnMgO.

5. The quantum dot light-emitting device according to claim 4, characterized in that, The red sub-pixel electron transport layer, the green sub-pixel electron transport layer, and the blue sub-pixel electron transport layer are ZnMgO nanoparticle thin films or ZnMgO thin films, and the weight percentage of Mg in the ZnMgO of the red sub-pixel electron transport layer is less than the weight percentage of Mg in the ZnMgO of the green sub-pixel electron transport layer, and the weight percentage of Mg in the ZnMgO of the green sub-pixel electron transport layer is less than the weight percentage of Mg in the ZnMgO of the blue sub-pixel electron transport layer.

6. The quantum dot light-emitting device according to claim 1, characterized in that, The charge carrier transport layer is a hole transport layer, and the material of the hole transport layer is selected from any one or more of organic hole transport materials and inorganic metal oxide hole transport materials. The organic hole transport material includes any one or more of poly(9,9-dioctylfluorene-CO-N-(4-butylphenyl)diphenylamine), polyvinylcarbazole, N,N′-bis(3-methylphenyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine and 4,4′-di(9-carbazole)biphenyl; The inorganic metal oxide hole transport material includes any one or more of NiO, NiO2, and V2O5.

7. The quantum dot light-emitting device according to claim 6, characterized in that, The hole transport layer includes a first hole transport layer close to the quantum dot light-emitting layer and a second hole transport layer away from the quantum dot light-emitting layer. The material of the first hole transport layer is a first hole transport material, and the material of the second hole transport layer is a second hole transport material. -6.2eV≤│HOMO(A)│≤-5.5eV; -5.5eV≤│HOMO(B)│≤-5.0eV Wherein, HOMO(A) is the highest occupied molecular orbital HOMO energy level of the first hole transport material, and HOMO(B) is the highest occupied molecular orbital HOMO energy level of the second hole transport material.

8. The quantum dot light-emitting device according to claim 1, characterized in that, The carrier transport layer is located on both sides of the quantum dot light-emitting layer. The carrier transport layer on one side of the quantum dot light-emitting layer is an electron transport layer, and the carrier transport layer on the other side of the quantum dot light-emitting layer is a hole transport layer. The electron transport layer comprises an inorganic metal oxide nanoparticle film or an inorganic metal oxide film, wherein the inorganic metal oxide is selected from any one or more of ZnO, TiO2, SnO2 and ZrO2; wherein ZnO includes metal-doped ZnO, and the metal doped in the metal-doped ZnO is selected from any one or more of Mg, Al, Zr and Y. The material of the hole transport layer is selected from any one or more of organic hole transport materials and inorganic metal oxide hole transport materials; wherein, the organic hole transport material includes any one or more of poly(9,9-dioctylfluorene-CO-N-(4-butylphenyl)diphenylamine), polyvinylcarbazole, N,N′-bis(3-methylphenyl)-N,N′-diphenyl-1,1′-biphenyl-4,4′-diamine and 4,4'-di(9-carbazole)biphenyl; the inorganic metal oxide hole transport material includes any one or more of NiO, NiO2 and V2O5.

9. The quantum dot light-emitting device according to claim 8, characterized in that, The electron transport layer includes a red sub-pixel electron transport layer, a green sub-pixel electron transport layer, and a blue sub-pixel electron transport layer; The red sub-pixel electron transport layer is an inorganic metal oxide nanoparticle thin film or an inorganic metal oxide thin film, wherein the inorganic metal oxide is ZnO or ZnMgO. The green sub-pixel electron transport layer is an inorganic metal oxide nanoparticle thin film or an inorganic metal oxide thin film, wherein the inorganic metal oxide is ZnO or ZnMgO. The blue sub-pixel electron transport layer is an inorganic metal oxide nanoparticle thin film or an inorganic metal oxide thin film, wherein the inorganic metal oxide is ZnO or ZnMgO.

10. The quantum dot light-emitting device according to claim 9, characterized in that, The red sub-pixel electron transport layer, the green sub-pixel electron transport layer, and the blue sub-pixel electron transport layer are ZnMgO nanoparticle thin films or ZnMgO thin films, and the weight percentage of Mg in the ZnMgO of the red sub-pixel electron transport layer is less than the weight percentage of Mg in the ZnMgO of the green sub-pixel electron transport layer, and the weight percentage of Mg in the ZnMgO of the green sub-pixel electron transport layer is less than the weight percentage of Mg in the ZnMgO of the blue sub-pixel electron transport layer.

11. The quantum dot light-emitting device according to claim 8, characterized in that, The hole transport layer includes a first hole transport layer close to the quantum dot light-emitting layer and a second hole transport layer away from the quantum dot light-emitting layer. The material of the first hole transport layer is a first hole transport material, and the material of the second hole transport layer is a second hole transport material. -6.2eV≤│HOMO(A)│≤-5.5eV; -5.5eV≤│HOMO(B)│≤-5.0eV Wherein, HOMO(A) is the highest occupied molecular orbital HOMO energy level of the first hole transport material, and HOMO(B) is the highest occupied molecular orbital HOMO energy level of the second hole transport material.

12. The quantum dot light-emitting device according to claim 7 or 11, characterized in that, The first hole transport material is selected from any one or two of 4,4',4''-tris(carbazole-9-yl)triphenylamine and 4,4'-cyclohexylbis[N,N-di(4-methylphenyl)aniline], and the second hole transport material is selected from any one or two of 4,4'-bis[N-(1-naphthyl)-N-phenylamino]biphenyl and 4,4',4''-tris(N-3-methylphenyl-N-phenylamino)triphenylamine.

13. The quantum dot light-emitting device according to claim 7 or 11, characterized in that, The hole transport layer has a thickness of 20 nm to 60 nm, and the first hole transport layer has a thickness of T. A 0nm < T A ≤10nm, the thickness of the second hole transport layer is T B ,20nm≤T B ≤60nm.

14. A method for fabricating a quantum dot light-emitting device according to any one of claims 1 to 13, characterized in that, include: Forming a quantum dot light-emitting layer; Forming a carrier transport layer; as well as A monolayer is formed between the charge carrier transport layer and the quantum dot light-emitting layer.

15. The preparation method according to claim 14, characterized in that, The monolayer is a self-assembled monolayer, and the formation of the monolayer includes: The monolayer material is dissolved in a solvent to form a solution containing the monolayer material; The monolayer is formed by immersion film formation or spin coating of the solution containing the monolayer material.

16. The preparation method according to claim 15, characterized in that, The immersion film formation temperature is room temperature, the immersion time is 20 min to 50 min, and the solvent for dissolving the monolayer is selected from any one or more of ethanol, diethyl ether, acetic acid, alkanes, N,N-dimethylformamide, and dimethyl sulfoxide.

17. The preparation method according to claim 14, characterized in that, The material of the monolayer is a ligand, and the preparation method includes: Provides initial quantum dots containing oil-soluble ligands; The oil-soluble ligands on the surface of the initial quantum dots are exchanged using the ligands to obtain quantum dots containing ligands; The quantum dot containing the ligand is used to form the quantum dot luminescent layer and the monolayer.

18. The preparation method according to claim 17, characterized in that, The process of exchanging the oil-soluble ligands on the surface of the initial quantum dots with the ligands to obtain quantum dots containing ligands includes: The ligand is dissolved in an organic solvent to obtain a ligand solution; The initial quantum dots are added to the ligand solution to obtain a ligand solution containing the initial quantum dots. The solution is stirred to allow the ligands to exchange ligands with the oil-soluble ligands on the surface of the initial quantum dots. The solution after ligand exchange is added to a poor solvent containing the ligands, causing the quantum dots containing the ligands to precipitate and separate from the solution.

19. The preparation method according to claim 18, characterized in that, The organic solvent is selected from any one or more alcohol solvents, and the unsuitable solvent for the ligand is water.

20. A display device, characterized in that, It includes multiple quantum dot light-emitting devices according to any one of claims 1 to 13.

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