Quantum dot composite material, preparation method thereof and light-emitting device

Abstract

The application belongs to the technical field of photoelectricity, and particularly relates to a quantum dot composite material and a preparation method thereof, and a light-emitting device. The quantum dot composite material comprises a quantum dot material, a metal two-dimensional alkene material and / or a sulfidized metal two-dimensional alkene material. In the quantum dot composite material, the metal two-dimensional alkene material and / or the sulfidized metal two-dimensional alkene material can provide a high-mobility transmission channel for charges on the surface of the quantum dot material, reduce the accumulation of charges on the surface of the quantum dot, and improve the heat dissipation performance of the quantum dot material. When the quantum dot composite material is applied to the light-emitting device, the working temperature of the light-emitting area of the device can be reduced, so that the stability and safety of the device are improved, and the service life is prolonged.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of optoelectronics, and particularly relates to a quantum dot composite material and a preparation method thereof, and a light-emitting device. BACKGROUND

[0002] A quantum dot light-emitting diode (QLED) has become a new generation of excellent display technology due to its high light-emitting efficiency, high color purity, narrow light-emitting spectrum, adjustable emission wavelength, and other advantages. QLED has a better competitive advantage than OLED and traditional LCD in color purity, color saturation, and production cost. At present, although the multi-layer semiconductor sandwich structure of the quantum dot device can optimize the exciton recombination of the quantum dots, the complicated combination of semiconductor materials will inevitably cause the problems of electric conduction and heat conduction, resulting in device heating, charge accumulation, and other problems. Therefore, the quantum dot device still has many problems that are difficult to solve, and therefore the QLED screen cannot be mass-produced commercially.

[0003] At present, charge accumulation and heating in the quantum dot light-emitting layer are one of the key reasons affecting the light-emitting efficiency, service life, and safety of the OLED device. SUMMARY

[0004] The purpose of the present application is to provide a quantum dot composite material and a preparation method thereof, and a light-emitting device, which aims to solve the technical problems of charge accumulation and heating in the quantum dot light-emitting layer to some extent.

[0005] To achieve the above-mentioned application purposes, the technical solutions adopted by the present application are as follows:

[0006] In a first aspect, the present application provides a quantum dot composite material, which comprises a quantum dot material, and further comprises a metal two-dimensional olefin material and / or a sulfidized metal two-dimensional olefin material.

[0007] In the quantum dot composite material provided by the first aspect of the present application, through the interaction between the metal two-dimensional olefin material and / or the sulfidized metal two-dimensional olefin material and the quantum dot material, a high-mobility charge transport channel can be provided, the charge accumulation on the surface of the quantum dots can be reduced, and the charge injection can be smoother. At the same time, the heat dissipation performance of the quantum dot material can be improved, the working temperature of the light-emitting region of the device can be reduced, and thus the stability and safety of the device can be improved, and the service life can be prolonged.

[0008] In a second aspect, the present application provides a preparation method of a quantum dot composite material, which comprises the following steps:

[0009] Obtaining a metal two-dimensional olefin material and / or a sulfidized metal two-dimensional olefin material;

[0010] Dispersing the metal two-dimensional olefin material, the sulfidized metal two-dimensional olefin material, and the quantum dot material in an organic solvent, and mixing and treating to obtain a quantum dot composite material.

[0011] The preparation method of the quantum dot composite material provided in the second aspect of the present application is simple in process, suitable for industrialized mass production and application, and the metal two-dimensional ene material and / or sulfidized metal two-dimensional ene material in the prepared quantum dot composite material can improve the charge mobility of the surface of the quantum dot, improve the charge transmission between quantum dot particles, reduce the accumulation of charges in the light-emitting layer, and at the same time improve the heat conduction performance of the light-emitting layer and reduce the heating phenomenon of the light-emitting layer, thereby improving the stability and safety of the device and prolonging the service life.

[0012] In the third aspect, the present application provides a light-emitting device comprising a quantum dot light-emitting layer, wherein the quantum dot light-emitting layer comprises the quantum dot composite material described above or the quantum dot composite material prepared by the method described above.

[0013] The quantum dot light-emitting layer of the light-emitting device provided in the third aspect of the present application comprises the quantum dot composite material described above, which can effectively reduce the charge accumulation in the quantum dot light-emitting layer, improve the heat conduction performance of the light-emitting layer, reduce the heating phenomenon of the light-emitting layer, thereby improving the stability and safety of the light-emitting device and prolonging the service life. BRIEF DESCRIPTION OF DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative effort.

[0015] Figure 1 is a preparation method of a quantum dot composite material provided by the embodiments of the present application;

[0016] Figure 2 is a schematic diagram of a positive type structure of a quantum dot light-emitting diode provided by the embodiments of the present application;

[0017] Figure 3 is a schematic diagram of a negative type structure of a quantum dot light-emitting diode provided by the embodiments of the present application. DETAILED DESCRIPTION

[0018] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not to limit the present application.

[0019] The first aspect of the embodiments of the present application provides a quantum dot composite material, which comprises a quantum dot material, and further comprises a metal two-dimensional ene material and / or a sulfidized metal two-dimensional ene material.

[0020] In the quantum dot composite material provided by the first aspect of the present application, the metal two-dimensional ene material and / or the sulfurized metal two-dimensional ene material has a honeycomb-like two-dimensional network structure, which is conducive to the rapid movement of electrons along the edges of the network lattice, provides a high-mobility charge transport channel, reduces the accumulation of charges on the surface of the quantum dots, and makes the charge injection more smooth, thereby further improving the light-emitting life. On the other hand, the two-dimensional sheet material itself has good heat dissipation performance, and the two-dimensional network honeycomb structure of the metal two-dimensional ene material is a non-complete planar undulating honeycomb structure with a certain undulation. This periodic undulation reduces the scattering between phonons, thereby further improving the heat dissipation performance. In addition, in the sulfurized metal two-dimensional ene material, the sulfur element opens part of the conjugated ene bond in the form of an S atom connected to the metal two-dimensional ene material in an additive manner. The sulfur atom with a larger atomic radius can further improve the undulation of the material, thereby further improving the heat dissipation performance of the composite material. Moreover, the addition of the sulfur atom is also conducive to the coordination of the metal two-dimensional ene material and the quantum dots, thereby improving the stability of the quantum dot composite material. When the quantum dot composite material provided by the embodiments of the present application is applied to a light-emitting device, the interaction between the metal two-dimensional ene material and / or the sulfurized metal two-dimensional ene material and the quantum dot material can effectively reduce the charge accumulation in the quantum dot light-emitting layer, improve the heat dissipation performance of the light-emitting layer, reduce the heating phenomenon of the light-emitting layer, thereby improving the stability and safety of the device and prolonging the service life.

[0021] In some embodiments, the mass ratio of the total mass of the metal two-dimensional ene material and the sulfurized metal two-dimensional ene material to the mass of the quantum dot material is 1:(15-30). The two-dimensional ene material and the quantum dot material have an optimal synergistic effect at this mass ratio. If the content of the metal two-dimensional ene material and the sulfurized metal two-dimensional ene material in the composite material is too low, the charge accumulation and heating of the quantum dot material cannot be improved well. If the content of the metal two-dimensional ene material and the sulfurized metal two-dimensional ene material is too high, the content of the quantum dot material in the composite material is too low, thereby reducing the light-emitting efficiency of the composite material. In some specific embodiments, the mass ratio of the total mass of the metal two-dimensional ene material and the sulfurized metal two-dimensional ene material to the mass of the quantum dot material can be 1:15, 1:17, 1:19, 1:20, 1:22, 1:25, 1:28, or 1:30, etc.

[0022] In some embodiments, the metal two-dimensional olefin material is selected from at least one of germanene, stannene, plumbene, which has a honeycomb-like two-dimensional network structure, and electrons can move quickly along the edges of the network lattice, thereby improving the charge mobility on the surface of the quantum dot, improving the charge transport between quantum dot particles, and reducing the accumulation of electrons in the light-emitting layer. At the same time, the two-dimensional network honeycomb structure of the metal two-dimensional olefin material is a non-complete planar undulating honeycomb structure with a certain degree of undulation. This periodic undulation reduces the scattering between phonons, improves the heat dissipation performance of the quantum dot composite material, and reduces the heating phenomenon of the light-emitting layer, thereby improving the stability and safety of the device and prolonging the service life.

[0023] In some embodiments, the sulfurized metal two-dimensional olefin material is selected from at least one of sulfurized germanene, sulfurized stannene, and sulfurized plumbene. These sulfurized metal two-dimensional olefin materials, the sulfur element opens part of the olefin conjugate bond in an additive manner, and is connected to the surface of the metal two-dimensional olefin material in the form of S atoms. The introduction of S atoms on the surface of the metal two-dimensional olefin material uniformly opens part of the π bond, and the S atom with a larger atomic radius can further improve the undulation of the material, thereby further improving the heat dissipation performance of the material. The electrically neutral S atom does not affect the original charge conjugate structure of the metal two-dimensional olefin material, so it does not reduce the charge transport performance of the material. In addition, the S atom can form a coordination bond with the metal on the surface of the quantum dot, so the addition of S atoms to the metal two-dimensional olefin material is also conducive to the coordination and combination of the metal two-dimensional olefin material and the quantum dot.

[0024] In some embodiments, in the sulfurized metal two-dimensional olefin material, 0.5% to 5% of the olefin conjugate bond is sulfurized and added, that is, 0.5% to 5% of the olefin conjugate bond of the metal two-dimensional olefin material is sulfurized and added to form the sulfurized metal two-dimensional olefin material. The metal two-dimensional olefin material with this degree of sulfurization effectively improves the heat dissipation performance of the metal two-dimensional olefin material, and at the same time improves the coordination and combination of the sulfurized metal two-dimensional olefin material and the quantum dot material, thereby improving the stability of the composite material. If the degree of sulfurization of the metal two-dimensional olefin material is too high, it will destroy the two-dimensional honeycomb network structure of the metal two-dimensional olefin material, thereby reducing the heat dissipation performance of the material and the charge transport performance of the metal two-dimensional material. In some specific embodiments, in the sulfurized metal two-dimensional olefin material, 0.5%, 1%, 2%, 3%, 4%, or 5% of the olefin conjugate bond is sulfurized and added.

[0025] In some embodiments, the sheet diameter of the metal dichalcogenide material is 0.5-5 nm. In some embodiments, the sheet diameter of the metal dichalcogenide material is 0.5-5 nm. In the composite material of the embodiments of the present application, the sheet diameter of the metal dichalcogenide material and / or the sheet diameter of the sulfurized metal dichalcogenide material is small and uniform, and has a larger effective specific surface area, which is conducive to the interaction between the metal dichalcogenide material and the quantum dot material in the composite material, and better improves the charge migration on the surface of the quantum dot material, reduces the accumulation of charges, and improves the heat dissipation performance of the quantum dot composite material. In addition, the small sheet diameter of the material is more conducive to the preparation of a luminescent layer film with a dense film layer, a uniform thickness, and a smooth surface, which is conducive to reducing the interface impedance and improving the binding tightness between adjacent functional layers, so that it has better application performance in a light-emitting device. In some specific embodiments, the sheet diameter of the metal dichalcogenide material is 0.5 nm, 1 nm, 2 nm, 3 nm, 4 nm, or 5 nm. In some specific embodiments, the sheet diameter of the sulfurized metal dichalcogenide material is 0.5 nm, 1 nm, 2 nm, 3 nm, 4 nm, or 5 nm.

[0026] In some embodiments, the quantum dot material in the quantum dot composite material includes, but is not limited to, at least one of the following: a group II-IV, a group II-VI, a group II-V, a group III-V, a group III-VI, a group IV-VI, a group I-III-VI, a group II-IV-VI, a group II-IV-V semiconductor compound, or a core-shell structure semiconductor compound composed of at least two of the above semiconductor compounds. In some specific embodiments, the quantum dot material is selected from at least one semiconductor nanocrystal compound of CdSe, CdS, CdTe, ZnO, ZnSe, ZnS, ZnTe, HgS, HgSe, HgTe, CdZnSe, or a semiconductor nanocrystal compound with a structure of a mixed type, a gradient mixed type, a core-shell structure type, or a combined type, etc., composed of at least two of the above semiconductor nanocrystal compounds. In some other specific embodiments, the quantum dot material is selected from at least one semiconductor nanocrystal compound of InAs, InP, InN, GaN, InSb, InAsP, InGaAs, GaAs, GaP, GaSb, AlP, AlN, AlAs, AlSb, CdSeTe, ZnCdSe, or a semiconductor nanocrystal compound with a structure of a mixed type, a gradient mixed type, a core-shell structure type, or a combined type, etc., composed of at least two of the above semiconductor nanocrystal compounds. In some other embodiments, the quantum dot material is selected from at least one of the following: a perovskite nanoparticle material (especially a luminescent perovskite nanoparticle material), a metal nanoparticle material, and a metal oxide nanoparticle material. Each of the above quantum dot materials has the characteristics of a quantum dot and good photoelectric performance.

[0027] In some embodiments, the quantum dot material is an oily quantum dot, and a ligand that is soluble in a low-polarity solvent is connected to the surface of the quantum dot material, and the ligand includes at least one of an acid ligand, a thiol ligand, an amine ligand, a (oxygen) phosphine ligand, a phospholipid, a soft phospholipid, a polyvinylpyridine, or the like. In some embodiments, the acid ligand is at least one of decanoic acid, undecylenic acid, myristic acid, oleic acid, stearic acid; the thiol ligand is at least one of octyl mercaptan, dodecyl mercaptan, octadecyl mercaptan; the amine ligand includes at least one of oleylamine, octadecylamine, octylamine; and the (oxygen) phosphine ligand is at least one of trioctylphosphine and trioctylphosphine oxide.

[0028] In some embodiments, the particle size of the quantum dot material ranges from 2 nm to 10 nm. If the particle size is too small, the film-forming property of the quantum dot material is poor, and the energy resonance transfer effect between quantum dot particles is significant, which is not conducive to the application of the material. If the particle size is too large, the quantum effect of the quantum dot material is weakened, resulting in a decline in the photoelectric performance of the material.

[0029] In some embodiments, the concentration of the quantum dot material in the solution of the quantum dot composite material ranges from 1 mg / mL to 200 mg / mL, and is preferably 20 mg / mL to 50 mg / mL. In this concentration range, the solution processing property of the quantum dot composite material is good, and the dispersibility is good.

[0030] In some embodiments, the quantum dot composite material includes the quantum dot material and the metal two-dimensional olefin material. In other embodiments, the quantum dot composite material includes the quantum dot material and the sulfidized metal two-dimensional olefin material. In other embodiments, the quantum dot composite material includes the quantum dot material, the metal two-dimensional olefin material, and the sulfidized metal two-dimensional olefin material.

[0031] The quantum dot composite material of the embodiments of the present application can be prepared by the following embodiment method.

[0032] As shown in FIG. 1, the second aspect of the embodiments of the present application provides a preparation method of a quantum dot composite material, including the steps of: Figure 1

[0033] S10. Obtaining a metal two-dimensional olefin material and / or a sulfidized metal two-dimensional olefin material;

[0034] S20. Dispersing the metal two-dimensional olefin material, the sulfidized metal two-dimensional olefin material, and the quantum dot material in an organic solvent, and mixing and processing to obtain a quantum dot composite material.

[0035] ​The second aspect of the present application provides a preparation method of the quantum dot composite material. The metal two-dimensional olefin material, the sulfidized metal two-dimensional olefin material and the quantum dot material are dispersed in an organic solvent. Through mixing treatment, the metal two-dimensional olefin material and / or the sulfidized metal two-dimensional olefin material are combined with the quantum dot material to form a solution of the quantum dot composite material. The solution of the quantum dot composite material can be directly applied to prepare a quantum dot light-emitting layer film. The preparation method of the quantum dot composite material provided by the embodiments of the present application is simple in process and suitable for industrial large-scale production and application. The prepared quantum dot composite material improves the charge mobility of the quantum dot surface, improves the charge transmission between quantum dot particles, reduces the accumulation of charges in the light-emitting layer, and improves the heat dissipation performance of the light-emitting layer, thereby improving the stability and safety of the device and prolonging the service life.

[0036] Specifically, in the step S10, the step of obtaining the metal two-dimensional olefin material includes: performing heat treatment on the metal two-dimensional olefin material in an atmosphere containing a gaseous sulfur source, so that the sulfur element opens part of the conjugated olefin bond in an additive manner to form S atoms connected to the metal two-dimensional olefin material, thereby obtaining the sulfidized metal two-dimensional olefin material. By introducing sulfur atoms with a large atomic radius into the metal two-dimensional material, the undulation of the metal two-dimensional material is further improved, thereby further improving the heat dissipation performance of the material. The electrically neutral sulfur atoms do not affect the reduction of the charge conjugation structure of the material and do not reduce the electron transport mobility performance of the material. In addition, the introduced sulfur atoms can combine with the metal on the surface of the quantum dot to form a coordination bond, thereby facilitating the coordination combination of the metal two-dimensional material and the quantum dot and improving the stability of the quantum dot composite material.

[0037] In some embodiments, the atmosphere containing the gaseous sulfur source includes: hydrogen sulfide and inert gas with a volume ratio of (0.5-5):(95-99.5). The sulfur source atmosphere with the above ratio not only facilitates the attack of hydrogen sulfide on the olefin conjugation bond in the metal two-dimensional olefin material, but also effectively regulates the sulfidation ratio of sulfur atoms in the metal two-dimensional olefin material, thereby facilitating the preparation of the sulfidized metal two-dimensional olefin material with a suitable sulfidation rate. If the concentration of hydrogen sulfide gas is too high, the two-dimensional honeycomb network structure of the metal two-dimensional olefin material will be excessively destroyed, thereby reducing the electrical conductivity and thermal conductivity of the material. In some specific embodiments, the atmosphere containing the gaseous sulfur source includes a gas with a volume percentage of 0.5%, 1%, 2%, 3%, 4% or 5%, and the rest is inert gas such as nitrogen, argon and helium. The inert gas can avoid the decomposition of the metal two-dimensional olefin material in the air at high temperature.

[0038] In some embodiments, the heat treatment conditions include: reacting for 10-30 minutes at a temperature of 80-150°C, which is beneficial for the chemical bond of the metal two-dimensional olefin material to be active, for the hydrogen sulfide gas to attack the metal two-dimensional olefin material olefin conjugate bond, and for the sulfur element to open part of the conjugate olefin bond in an addition manner to be connected to the metal two-dimensional olefin material in the form of an S atom.

[0039] Specifically, in the step S20, the mixing process includes: dispersing the metal two-dimensional olefin material, the sulfidized metal two-dimensional olefin material, and the quantum dot material in an organic solvent at a mass ratio of the total mass of the metal two-dimensional olefin material and the sulfidized metal two-dimensional olefin material to the mass of the quantum dot material being 1:(15-30), mixing for 10-60 minutes, and making the metal two-dimensional olefin material and / or the sulfidized metal two-dimensional olefin material fully contact and react with the quantum dot material to form a quantum dot composite material in a coordination form to obtain a solution of the quantum dot composite material. The solution of the quantum dot composite material can be directly applied to deposit and prepare a quantum dot light-emitting layer film, or can be stored in the form of the quantum dot composite material after being dried.

[0040] In some embodiments, the organic solvent is selected from at least one of: an alkane-based solvent, a halogenated aromatic hydrocarbon-based solvent, an alcohol ether-based solvent, an alcohol-based organic solvent. In some specific embodiments, the alkane-based solvent includes one or more of n-hexane, cyclohexane, hexane, n-octane. In some specific embodiments, the halogenated aromatic hydrocarbon-based solvent includes one or more of bromobenzene, iodobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,2-dibromobenzene 225, 1,3-dibromobenzene, o-chlorotoluene, p-chlorotoluene, o-bromotoluene, p-bromotoluene. In some specific embodiments, the alcohol ether-based solvent is one or more of ethylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol propyl ether, ethylene glycol butyl ether, propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol n-propyl ether, propylene glycol isopropyl ether, propylene glycol n-butyl ether, propylene glycol t-butyl ether, diethylene glycol ether, diethylene glycol methyl ether, diethylene glycol dimethyl ether, diethylene glycol ethyl ether, diethylene glycol diethyl ether, diethylene glycol butyl ether, diethylene glycol dibutyl ether, diethylene glycol hexyl ether, dipropylene glycol methyl ether, dipropylene glycol dimethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol diethyl ether, dipropylene glycol butyl ether, triethylene glycol ethyl ether, tripropylene glycol methyl ether, tripropylene glycol butyl ether. In some specific embodiments, the alcohol-based organic solvent includes n-butanol, isobutanol, sec-butanol, t-butanol, amyl alcohol, isoamyl alcohol, sec-amyl alcohol, sec-isoamyl alcohol, 3-pentanol, t-amyl alcohol, cyclopentanol, 2-methyl-1-butanol, 2-methylpentanol, 4-methyl-2-pentanol, n-hexanol, 2-hexanol, 2-ethylbutanol, 2-methylpentanol, 2-methyl-2-pentanol, 2-methyl-3-pentanol, 3-ethyl-3-pentanol, n-heptanol, 2-heptanol, 3-heptanol, 2-ethylhexanol, 2-methylcyclohexanol, n-octanol, 2-octanol, 3,5,5-trimethylhexanol, nonanol, 2,6-dimethyl-4-heptanol, n-decanol, 5-ethyl-2-nonanol, undecanol, 5-ethyl-2-nonanol, dodecanol, trimethyl nonanol, cis-2-methylcyclohexanol, cis-3-methylcyclohexanol, cis-4-methylcyclohexanol, 2-butoxyethanol, benzyl alcohol, a-phenyl ethanol, or β-phenyl ethanol. The organic solvent in the above embodiments of the present application has good solubility and dispersion effect on the quantum dot material, the metal two-dimensional olefin material, and the sulfided metal two-dimensional olefin material, which is conducive to the mutual coordination and combination between the metal two-dimensional olefin material and / or the sulfided metal two-dimensional olefin material and the quantum dot material, and forms a quantum dot composite material.

[0041] In some embodiments, the metal two-dimensional olefin material is selected from at least one of germanene, stannene, plumbene.

[0042] In some embodiments, the sulfided metal two-dimensional olefin material is selected from at least one of sulfided germanene, sulfided stannene, sulfided plumbene.

[0043] In some embodiments, in the sulfided metal two-dimensional olefin material, 0.5% to 5% of the conjugate bonds of the olefin are sulfided and added.

[0044] In some embodiments, the metal two-dimensional olefin material has a sheet diameter of 0.5-5 nm.

[0045] In some embodiments, the sulfurized metal two-dimensional olefin material has a sheet diameter of 0.5-5 nm.

[0046] The technical effects of the above-mentioned embodiments of the present application are discussed in detail throughout the text, and will not be repeated here.

[0047] The third aspect of the embodiments of the present application provides a light-emitting device, which comprises a quantum dot light-emitting layer containing the above-mentioned quantum dot composite material or the quantum dot composite material prepared by the above-mentioned method.

[0048] The quantum dot light-emitting layer of the light-emitting device provided by the third aspect of the present application contains the above-mentioned quantum dot composite material, which can effectively reduce the charge accumulation in the quantum dot light-emitting layer, improve the heat conduction performance of the light-emitting layer, reduce the heating phenomenon of the light-emitting layer, thereby improving the stability and safety of the light-emitting device and prolonging the service life.

[0049] In the embodiments of the present application, the device is not limited by the device structure, and can be a device of positive type structure or a device of reverse type structure.

[0050] In an embodiment, the light-emitting device of positive type structure comprises a laminated structure of oppositely arranged anode and cathode, a light-emitting layer arranged between the anode and the cathode, and the anode arranged on a substrate. Further, a hole injection layer, a hole transport layer, an electron blocking layer and other hole functional layers can be arranged between the anode and the light-emitting layer; an electron transport layer, an electron injection layer and a hole blocking layer and other electron functional layers can be arranged between the cathode and the light-emitting layer, as shown in FIG. 1. In some embodiments of the specific positive type structure device, the light-emitting device comprises a substrate, an anode arranged on the surface of the substrate, a hole transport layer arranged on the surface of the anode, a light-emitting layer arranged on the surface of the hole transport layer, an electron transport layer arranged on the surface of the light-emitting layer, and a cathode arranged on the surface of the electron transport layer. Figure 2

[0051] In an embodiment, the light-emitting device of reverse type structure comprises a laminated structure of oppositely arranged anode and cathode, a light-emitting layer arranged between the anode and the cathode, and the cathode arranged on a substrate. Further, a hole injection layer, a hole transport layer, an electron blocking layer and other hole functional layers can be arranged between the anode and the light-emitting layer; an electron transport layer, an electron injection layer and a hole blocking layer and other electron functional layers can be arranged between the cathode and the light-emitting layer, as shown in FIG. 2. In some embodiments of the specific reverse type structure device, the light-emitting device comprises a substrate, a cathode arranged on the surface of the substrate, an electron transport layer arranged on the surface of the cathode, a light-emitting layer arranged on the surface of the electron transport layer, a hole transport layer arranged on the surface of the light-emitting layer, and an anode arranged on the surface of the hole transport layer. Figure 3 ​​

[0052] In some embodiments, the substrate is not limited in selection and can be either a rigid substrate or a flexible substrate. In some specific embodiments, the rigid substrate includes, but is not limited to, one or more of glass, metal foil. In some specific embodiments, the flexible substrate includes, but is not limited to, one or more of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyether ether ketone (PEEK), polystyrene (PS), polyether sulfone (PES), polycarbonate (PC), polyarylate (PAT), polyarylate (PAR), polyimide (PI), polyvinyl chloride (PVC), polyethylene (PE), polyvinylpyrrolidone (PVP), textile fiber.

[0053] In some embodiments, the anode material is not limited in selection and can be selected from doped metal oxides, including but not limited to one or more of indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO), antimony-doped tin oxide (ATO), aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO), indium-doped zinc oxide (IZO), magnesium-doped zinc oxide (MZO), aluminum-doped magnesium oxide (AMO). It can also be selected from composite electrodes with a metal sandwiched between doped or undoped transparent metal oxides, including but not limited to one or more of AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, ZnS / Al / ZnS, TiO2 / Ag / TiO2, TiO2 / Al / TiO2.

[0054] In some embodiments, the hole injection layer includes, but is not limited to, one or more of organic hole injection materials, doped or undoped transition metal oxides, doped or undoped metal chalcogenides. In some specific embodiments, the organic hole injection material includes, but is not limited to, one or more of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS), copper phthalocyanine (CuPc), 2,3,5,6-tetrafluoro-7,7',8,8'-tetracyanoquinodimethane (F4-TCNQ), 2,3,6,7,10,11-hexacyano-1,4,5,8,9,12-hexaazatriphenylene (HATCN). In some specific embodiments, the transition metal oxide includes, but is not limited to, one or more of MoO3, VO2, WO3, CrO3, CuO. In some specific embodiments, the metal chalcogenide includes, but is not limited to, one or more of MoS2, MoSe2, WS2, WSe2, CuS.

[0055] In some embodiments, the hole transport layer can be selected from organic materials having hole transport capability and / or inorganic materials having hole transport capability. In some specific embodiments, the organic materials having hole transport capability include, but are not limited to, one or more of poly(9,9-dioctylfluorene-CO-N-(4-butylphenyl)diphenylamine) (TFB), polyvinylcarbazole (PVK), poly(N,N'bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine) (poly-TPD), poly(9,9-dioctylfluorene-co-bis-N,N-phenyl-1,4-phenylenediamine) (PFB), 4,4,4"-tris(carbazol-9-yl)triphenylamine (TCTA), 4,4'-bis(9-carbazolyl) biphenyl (CBP), N,N'-diphenyl-N,N'-di(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD), N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB). In some specific embodiments, the inorganic materials having hole transport capability include, but are not limited to, one or more of doped graphene, non-doped graphene, C60, doped or non-doped MoO3, VO2, WO3, CrO3, CuO, MoS2, MoSe2, WS2, WSe2, CuS.

[0056] In some embodiments, the light-emitting layer includes the quantum dot composite described above.

[0057] In some embodiments, the material of the electron transport layer includes, but is not limited to, ZnO, TiO2, SnO, Ta2O3, AlZnO, ZnSnO, InSnO, Alq3, Ca, Ba, CsF, LiF, CsCO3, and the like.

[0058] In some embodiments, the cathode material can be one or more of various conductive carbon materials, conductive metal oxide materials, metal materials. In some specific embodiments, the conductive carbon materials include, but are not limited to, doped or non-doped carbon nanotubes, doped or non-doped graphene, doped or non-doped graphene oxide, C60, graphite, carbon fiber, porous carbon, or mixtures thereof. In some specific embodiments, the conductive metal oxide materials include, but are not limited to, ITO, FTO, ATO, AZO, or mixtures thereof. In some specific embodiments, the metal materials include, but are not limited to, Al, Ag, Cu, Mo, Au, or alloys thereof; among the metal materials, the morphology thereof includes, but is not limited to, dense thin film, nanowire, nanosphere, nanorod, nanotaper, nanohollow sphere, or mixtures thereof; preferably, the cathode of the light-emitting device is Ag, Al.

[0059] In some embodiments, the preparation of the light-emitting device of the present application includes the steps of:

[0060] S30. Obtain a substrate with an anode deposited thereon;

[0061] S40. Grow a hole transport layer on the surface of the anode;

[0062] S50. Subsequently deposit a quantum dot light emitting layer on the hole transport layer;

[0063] S60. Finally deposit an electron transport layer on the quantum dot light emitting layer, and evaporate a cathode on the electron transport layer to obtain a light emitting device.

[0064] Specifically, in step S30, in order to obtain a high-quality zinc oxide nanomaterial film, the ITO substrate needs to be pretreated. The basic specific treatment steps include: cleaning the ITO conductive glass with a cleaning agent to preliminarily remove the stains present on the surface, then sequentially ultrasonic cleaning in deionized water, acetone, anhydrous ethanol, and deionized water for 20 minutes respectively to remove impurities present on the surface, and finally blowing dry with high-purity nitrogen gas, thereby obtaining an ITO anode.

[0065] Specifically, in step S40, the step of growing a hole transport layer includes: placing the ITO substrate on a spin coater, and spin coating a film with a prepared hole transport material solution; controlling the film thickness by adjusting the concentration of the solution, the spin coating speed, and the spin coating time, and then performing thermal annealing treatment at an appropriate temperature.

[0066] Specifically, in step S50, the step of depositing a quantum dot light emitting layer on the hole transport layer includes: placing the substrate with the hole transport layer spin coated thereon on a spin coater, spin coating a film with a prepared solution of a quantum dot composite material with a certain concentration, controlling the thickness of the light emitting layer by adjusting the concentration of the solution, the spin coating speed, and the spin coating time, about 20-60 nm, and drying at an appropriate temperature.

[0067] Specifically, in step S60, the step of depositing an electron transport layer on the quantum dot light emitting layer includes: the electron transport layer is an electron transport composite material of the present application; placing the substrate with the quantum dot light emitting layer spin coated thereon on a spin coater, spin coating a film with a prepared solution of the electron transport composite material with a certain concentration by drop coating, spin coating, soaking, coating, printing, evaporation, etc., controlling the thickness of the electron transport layer by adjusting the concentration of the solution, the spin coating speed (preferably, the rotation speed is between 2000-6000 rpm), and the spin coating time, about 5-100 nm, and then annealing the film at 200-250°C to sufficiently remove the solvent.

[0068] Specifically, in step S60, the step of preparing a cathode includes: placing the substrate with the deposited functional layers in an evaporation chamber to evaporate a layer of 15-30 nm of metal silver or aluminum as a cathode through a mask.

[0069] In further embodiments, the obtained QLED device is subjected to encapsulation treatment. The encapsulation treatment can be performed by using a common machine or by using manual encapsulation. Preferably, the oxygen content and water content in the environment of the encapsulation treatment are both less than 0.1 ppm, so as to ensure the stability of the device.

[0070] In order to enable the above-mentioned implementation details and operations of the present application to be clearly understood by those skilled in the art, and the significant performance of the quantum dot composite material and the preparation method thereof according to the embodiments of the present application to be embodied, the above-mentioned technical solutions are illustrated by means of multiple embodiments as follows.

[0071] Embodiment 1

[0072] A quantum dot composite material, the preparation thereof comprises the following steps:

[0073] 1. A two-dimensional stannene material with a sheet diameter of 0.5-3 nm is placed in a muffle furnace, heated to 120 degrees Celsius in an argon atmosphere, then 0.5% of H2S gas is introduced into the muffle furnace for 10 minutes, and then the gas supply is stopped. After 30 minutes of heat preservation, the sulfurized two-dimensional stannene material is taken out after cooling, and a 0.5% S-doped sulfurized two-dimensional stannene material is prepared.

[0074] 2. In an argon atmosphere, the sulfurized two-dimensional stannene material and CdSeS / ZnS green quantum dots with a particle size of 5-10 nm are dispersed in n-octane with a mass ratio of 1:20, and the concentration of the quantum dots is 40 mg / mL. The solution of the quantum dot composite material modified by the sulfurized two-dimensional stannene is prepared by stirring at 25 degrees Celsius for 30 minutes. It is prepared for the preparation of a QLED device.

[0075] A quantum dot light-emitting device, the preparation thereof comprises: sequentially spin-coating or depositing a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, and an electron transport layer onto an ITO substrate, and finally evaporating silver Ag on the electron transport layer to form a QLED device after encapsulation. The electron transport layer material is selected from zinc oxide ZnO, the hole transport layer material is selected from TFB, the hole injection layer is selected from PEDOT:PSS material, the cathode material is silver Ag, the anode substrate is an ITO substrate, and the material of the quantum dot light-emitting layer is the solution of the quantum dot composite material modified by the sulfurized two-dimensional stannene prepared in Embodiment 1.

[0076] Embodiment 2

[0077] A quantum dot composite material, the difference between the quantum dot composite material and Embodiment 1 mainly lies in that a two-dimensional plumbene material is used in step 1, and 1% of H2S gas is introduced into the muffle furnace to prepare a 1% S-doped sulfurized two-dimensional plumbene material. In step 2, the mass ratio of the sulfurized two-dimensional plumbene material to the quantum dot material is 1:18.

[0078] A quantum dot light-emitting device, which is mainly different from the embodiment 1 in that the material of the quantum dot light-emitting layer is a solution of the sulfurized two-dimensional germanene modified quantum dot composite material prepared in the embodiment 3.

[0079] Embodiment 3

[0080] A quantum dot composite material, which is mainly different from the embodiment 1 in that the two-dimensional germanene material is used in step 1; and 0.5% of H2S gas is introduced into the muffle furnace to prepare 0.5% of S-doped sulfurized two-dimensional germanene material. In step 2, the mass ratio of the sulfurized two-dimensional germanene material to the quantum dot material is 1:15.

[0081] A quantum dot light-emitting device, which is mainly different from the embodiment 1 in that the material of the quantum dot light-emitting layer is a solution of the sulfurized two-dimensional germanene modified quantum dot composite material prepared in the embodiment 3, and the electron transport layer material is titanium oxide TiO2.

[0082] Embodiment 4

[0083] A quantum dot composite material, which is mainly different from the embodiment 1 in that 2% of H2S gas is introduced into the muffle furnace to prepare 2% of S-doped sulfurized two-dimensional stannene material in step 1.

[0084] A quantum dot light-emitting device, which is mainly different from the embodiment 1 in that the material of the quantum dot light-emitting layer is a solution of the sulfurized two-dimensional stannene modified quantum dot composite material prepared in the embodiment 4.

[0085] Embodiment 5

[0086] A quantum dot composite material, which is mainly different from the embodiment 1 in that 5% of H2S gas is introduced into the muffle furnace to prepare 5% of S-doped sulfurized two-dimensional stannene material in step 1.

[0087] A quantum dot light-emitting device, which is mainly different from the embodiment 1 in that the material of the quantum dot light-emitting layer is a solution of the sulfurized two-dimensional stannene modified quantum dot composite material prepared in the embodiment 5.

[0088] Embodiment 6

[0089] A quantum dot composite material, which is mainly different from the embodiment 1 in that the mass ratio of the sulfurized two-dimensional stannene material to the quantum dot material is 1:30 in step 2.

[0090] A quantum dot light-emitting device, which is mainly different from the embodiment 1 in that the material of the quantum dot light-emitting layer is a solution of the sulfurized two-dimensional stannene modified quantum dot composite material prepared in the embodiment 6.

[0091] Embodiment 7

[0092] A quantum dot composite material, which is mainly different from example 1 in that the two-dimensional tinene material is not subjected to sulfidation treatment and directly prepared with the CdSeS / ZnS green quantum dot material to obtain the quantum dot composite material.

[0093] A quantum dot light-emitting device, which is mainly different from example 1 in that the material of the quantum dot light-emitting layer adopts the quantum dot composite material of example 7.

[0094] Example 8

[0095] A quantum dot composite material, which is mainly different from example 2 in that the two-dimensional leadene material is not subjected to sulfidation treatment and directly prepared with the CdSeS / ZnS green quantum dot material to obtain the quantum dot composite material.

[0096] A quantum dot light-emitting device, which is mainly different from example 2 in that the material of the quantum dot light-emitting layer adopts the quantum dot composite material of example 8.

[0097] Example 9

[0098] A quantum dot composite material, which is mainly different from example 3 in that the two-dimensional germanene material is not subjected to sulfidation treatment and directly prepared with the CdSeS / ZnS green quantum dot material to obtain the quantum dot composite material.

[0099] A quantum dot light-emitting device, which is mainly different from example 3 in that the material of the quantum dot light-emitting layer adopts the quantum dot composite material of example 9.

[0100] Comparative example 1

[0101] A quantum dot light-emitting device, which is mainly different from example 1 in that the material of the quantum dot light-emitting layer adopts the CdSeS / ZnS green quantum dot.

[0102] Comparative example 2

[0103] A quantum dot composite material, which is mainly different from example 1 in that 0.02% of H2S gas is introduced into the muffle furnace in step 1 to obtain a 0.02% S-doped sulfidized two-dimensional tinene material.

[0104] A quantum dot light-emitting device, which is mainly different from example 1 in that the material of the quantum dot light-emitting layer adopts the solution of the sulfidized two-dimensional tinene modified quantum dot composite material prepared in comparative example 2.

[0105] Comparative example 3

[0106] A quantum dot composite material, which is mainly different from example 1 in that 6% of H2S gas is introduced into the muffle furnace in step 1 to obtain a 6% S-doped sulfidized two-dimensional tinene material.

[0107] A quantum dot light-emitting device, which is mainly different from the embodiment 1 in that the material of the quantum dot light-emitting layer is a solution of the quantum dot composite material modified by the sulfidized two-dimensional stannene prepared in the comparative example 3.

[0108] Comparative example 4

[0109] A quantum dot composite material, which is mainly different from the embodiment 1 in that the mass ratio of the sulfidized two-dimensional stannene material to the quantum dot material in step 2 is 1:32.

[0110] A quantum dot light-emitting device, which is mainly different from the embodiment 1 in that the material of the quantum dot light-emitting layer is a solution of the quantum dot composite material modified by the sulfidized two-dimensional stannene prepared in the comparative example 4.

[0111] Comparative example 5

[0112] A quantum dot composite material, which is mainly different from the embodiment 1 in that the mass ratio of the sulfidized two-dimensional stannene material to the quantum dot material in step 2 is 1:10.

[0113] A quantum dot light-emitting device, which is mainly different from the embodiment 1 in that the material of the quantum dot light-emitting layer is a solution of the quantum dot composite material modified by the sulfidized two-dimensional stannene prepared in the comparative example 5.

[0114] Further, in order to verify the progressiveness of the quantum dot composite material and the preparation method thereof and the light-emitting device of the embodiments, the performance of the quantum dot light-emitting device provided by the embodiments 1-9 and the comparative examples 1-5 is tested as follows:

[0115] 1. Device T95_1knit lifetime (hours): refers to the lifetime of the device at 1000 nit initial brightness, the brightness decays to 95%;

[0116] 2. Voltage rise amplitude (V) at T95: refers to the voltage rise amplitude at 95% brightness;

[0117] 3. Device operating temperature: the temperature of the light-emitting area is measured using an infrared thermometer;

[0118] The test results are shown in Table 1 as follows:

[0119] Table 1

[0120]

[0121]

[0122] From the test results, the quantum dot light-emitting devices of Examples 1-6 and 7-9 have longer service life, lower working temperature, and much lower working voltage increase when reaching T95 than the device of Comparative Example 1, which indicates that the metal two-dimensional material and the sulfidized metal two-dimensional material in the quantum dot composite material of the present application can provide a high-mobility charge transport channel, reduce the charge accumulation on the surface of the quantum dots, and make the charge injection more smooth, thereby further improving the service life of the quantum dot light-emitting device. In addition, the sulfidized metal two-dimensional material can improve the heat dissipation performance of the light-emitting layer and reduce the working temperature of the light-emitting region, thereby slowing down the aging of the light-emitting material and other materials, and improving the service life of the QLED device.

[0123] Secondly, the quantum dot light-emitting devices of Examples 1-6 have lower working temperature and similar working voltage increase when reaching T95 than the quantum dot light-emitting devices of Examples 7-9, which indicates that the sulfidized metal two-dimensional material further improves the heat dissipation performance of the device.

[0124] In addition, by comparing the performance of the quantum dot light-emitting devices of Examples 1 and Comparative Examples 2 and 3, it can be seen that when the sulfidization degree of the metal two-dimensional material is too high or too low, the conductivity and thermal conductivity of the composite material will be reduced. By comparing Examples 1 and Comparative Examples 4 and 5, it can be seen that when the proportion of the quantum dot material in the composite material is too low or too high, the service life of the device will be adversely affected.

[0125] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A quantum dot composite material, characterized by, The quantum dot composite material comprises a quantum dot material, and further comprises a metal two-dimensional olefin material and / or a sulfide metal two-dimensional olefin material; the metal two-dimensional olefin material is selected from at least one of germanene, stannene, plumbene; the sulfide metal two-dimensional olefin material is selected from at least one of germanene sulfide, stannene sulfide, plumbene sulfide; in the sulfide metal two-dimensional olefin material, 0.5% to 5% of olefin conjugate bonds are sulfide addition; the mass ratio of the total mass of the metal two-dimensional olefin material and the sulfide metal two-dimensional olefin material to the mass of the quantum dot material is 1: (15-30); the flake diameter of the metal two-dimensional olefin material is 0.5-5 nm; the flake diameter of the sulfide metal two-dimensional olefin material is 0.5-5 nm.

2. The quantum dot composite of claim 1, wherein, The quantum dot material is selected from at least one semiconductor nanocrystal compound of CdSe, CdS, CdTe, ZnO, ZnSe, ZnS, ZnTe, HgS, HgSe, HgTe, CdZnSe, or at least two semiconductor nanocrystal compounds.

3. A method for producing the quantum dot composite material according to claim 1 or 2, characterized by, The method comprises the steps of: obtaining a metal two-dimensional olefin material and / or a sulfide metal two-dimensional olefin material; dispersing the metal two-dimensional olefin material, the sulfide metal two-dimensional olefin material and a quantum dot material in an organic solvent, and mixing to obtain a quantum dot composite material.

4. The method for preparing quantum dot composite materials as described in claim 3, characterized in that, The step of obtaining the sulfide metal two-dimensional olefin material comprises: heat treating the metal two-dimensional olefin material in an atmosphere containing a gaseous sulfur source to obtain the sulfide metal two-dimensional olefin material.

5. The method for preparing quantum dot composite materials as described in claim 4, characterized in that, The atmosphere containing the gaseous sulfur source comprises: hydrogen sulfide and inert gas in a volume ratio of (0.5-5):(95-99.5). And / or, the heat treatment conditions comprise: reacting at a temperature of 80-150°C for 10-30 minutes.

6. The method for preparing quantum dot composite materials according to any one of claims 3 to 5, characterized in that, The mixing step comprises: dispersing the metal two-dimensional olefin material, the sulfide metal two-dimensional olefin material and the quantum dot material in an organic solvent in a mass ratio of the total mass of the metal two-dimensional olefin material and the sulfide metal two-dimensional olefin material to the mass of the quantum dot material is 1: (15-30), and mixing for 10-60 minutes to obtain a solution of the quantum dot composite material.

7. The method for preparing quantum dot composite materials as described in claim 6, characterized in that, The organic solvent is selected from at least one of an alkane solvent, a halogenated aromatic hydrocarbon solvent, an alcohol ether solvent, and an alcohol organic solvent.

8. A light emitting device, characterized by The quantum dot light-emitting layer comprises the quantum dot composite material of any one of claims 1-2, or the quantum dot composite material prepared by the method of any one of claims 3-7.

9. The light emitting device of claim 8, wherein the first and second light emitting layers are formed of a material having a band gap of 2.5 eV or more. The quantum dot light-emitting layer comprises only the quantum dot composite material of any one of claims 1-2, or only the quantum dot composite material prepared by the method of any one of claims 3-7.

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