Method for modifying quantum dot material, modified quantum dot material, and light emitting device

Abstract

The application belongs to the technical field of display equipment, and particularly relates to a modification method of quantum dot material, modified quantum dot material and a light-emitting device. The modification method of quantum dot material comprises the following steps: obtaining a heterocyclic boronic acid compound, performing ammonia modification treatment on the heterocyclic boronic acid compound in an ammonia atmosphere to obtain an ammonia-modified heterocyclic boronic acid compound; obtaining quantum dot material, mixing the quantum dot material with the ammonia-modified heterocyclic boronic acid compound dissolved in a solvent to obtain modified quantum dot material. The modification method of quantum dot material has better capturing and injection effect on electrons, and has good stability, so that the modified quantum dot material with the ammonia-modified heterocyclic boronic acid ligand combined on the surface has better application prospect in quantum dot light-emitting devices.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of display devices, and particularly relates to a modification method of quantum dot material, modified quantum dot material, and a light-emitting device. BACKGROUND

[0002] Quantum dots are nanocrystalline particles with a radius less than or close to the Bohr exciton radius, and the size particle diameter is generally between 1-10 nm. Quantum dots have quantum confinement effect and can emit fluorescence after excitation. Moreover, quantum dots have unique light-emitting properties such as excitation peak width, emission peak narrowness, and light-emitting spectrum adjustability, so that quantum dot materials have broad application prospects in the field of photoelectric light-emitting. Quantum dot light-emitting diode (QLED) is a new type of display technology that has rapidly emerged in recent years. Quantum dot light-emitting diode is a device in which colloidal quantum dots are used as a light-emitting layer. By introducing a quantum dot light-emitting layer between different conductive materials, light of a desired wavelength can be obtained. Quantum dot light-emitting diode has advantages such as high color gamut, self-light-emitting, low start-up voltage, fast response speed, etc. Compared with organic electroluminescent diode (OLED), quantum dot light-emitting diode has advantages such as narrow light-emitting spectrum, wide color gamut, good stability, long service life, and low manufacturing cost.

[0003] Due to the small size, large specific surface area, and many surface defects and dangling bonds of quantum dots, it is necessary to add ligands to the surface of quantum dots during synthesis and application to improve the application performance of the material. The surface of common oil-based quantum dots often has long-chain surface ligands such as oleic acid and oleylamine attached during synthesis. Although these ligands can improve the dispersibility of quantum dots in non-polar solvents, the oleic acid and oleylamine ligands combined with the surface of quantum dots are not conducive to charge transport. SUMMARY

[0004] The present application aims to provide a modification method of quantum dot material, modified quantum dot material, and a light-emitting device, and aims to solve the problem of the surface ligands of oil-based quantum dot material being not conducive to charge transport to some extent.

[0005] To achieve the above application purpose, the technical scheme adopted by the present application is as follows:

[0006] In a first aspect, the present application provides a modification method of quantum dot material, comprising the following steps:

[0007] Obtaining a heterocyclic boronic acid compound, and performing ammonia modification treatment on the heterocyclic boronic acid compound under an ammonia atmosphere to obtain an ammonia-modified heterocyclic boronic acid compound;

[0008] Obtaining a quantum dot material, and mixing the quantum dot material with the ammonia-modified heterocyclic boronic acid compound in a solvent to obtain a modified quantum dot material.

[0009] In a second aspect, the application provides a modified quantum dot material, wherein the surface of the modified quantum dot material is combined with an ammonia-modified heterocyclic boronic acid ligand.

[0010] In a third aspect, the application provides an optoelectronic device, which comprises the modified quantum dot material prepared by the method described above or the modified quantum dot material described above.

[0011] The modified method of the quantum dot material provided in the first aspect of the application is to ammonia-modify the heterocyclic boronic acid compound, so as to protect the heterocyclic boronic acid compound from water absorption and denaturation, and reduce the acidity of the heterocyclic boronic acid compound to avoid the influence of the acidity of the heterocyclic boronic acid compound on the quantum dot material. In the modified quantum dot material, the B atom in the heterocyclic boronic acid ligand connected to the surface of the quantum dot material has strong electron-deficient properties and strong electron attraction ability, which can enhance the electron capture ability of the ligand on the surface of the quantum dot material. In addition, the heterocyclic group has rich electron cloud, which can efficiently transmit the electrons captured by the boronic acid end to the quantum dot, thereby improving the efficiency of electron transmission and injection into the quantum dot.

[0012] The modified quantum dot material provided in the second aspect of the application is combined with the ammonia-modified heterocyclic boronic acid ligand, which has better electron capture and injection effect and good stability, so that it has better application prospect in the quantum dot light-emitting device.

[0013] The optoelectronic device provided in the third aspect of the application comprises the modified quantum dot material combined with the ammonia-modified heterocyclic boronic acid ligand, which has high electron capture efficiency, improves the efficiency of electron transmission and injection into the quantum dot material, and has good stability. Therefore, the optoelectronic device provided in the application has high utilization rate of electrons in the light-emitting layer, effectively improves the recombination effect of carriers in the light-emitting layer, and effectively avoids the influence of charge accumulation on the service life of the device caused by low electron transmission and injection efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a flowchart of the modified method of the quantum dot material provided in the embodiments of the application;

[0015] Figure 2 is a schematic diagram of a positive type structure of the quantum dot light-emitting diode provided in the embodiments of the application;

[0016] Figure 3 is a schematic diagram of a negative type structure of the quantum dot light-emitting diode provided in the embodiments of the application. DETAILED DESCRIPTION

[0017] In order to make the technical problems, technical solutions and beneficial effects of the present application clearer, 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 intended to explain the present application and not to limit the present application.

[0018] The first aspect of the embodiments of the present application provides a modification method of quantum dot material, comprising the following steps:

[0019] S10. Obtain a heterocyclic boronic acid compound, and perform ammonia modification treatment on the heterocyclic boronic acid compound under an ammonia atmosphere to obtain an ammonia-modified heterocyclic boronic acid compound;

[0020] S20. Obtain a quantum dot material, and perform mixing treatment on the quantum dot material and the ammonia-modified heterocyclic boronic acid compound in a solvent to obtain a modified quantum dot material.

[0021] The modification method of quantum dot material provided by the first aspect of the present application, on the one hand, performs ammonia modification treatment on the heterocyclic boronic acid compound, ammonia is combined with the -OH bond on the heterocyclic boronic acid compound through coordination bond, passivates the -OH group of the boronic acid compound, and plays a role in protecting the heterocyclic boronic acid compound to avoid its water absorption and denaturation; meanwhile, the ammonia modification can also reduce the acidity of the heterocyclic boronic acid compound, avoid the influence of the acidity of the heterocyclic boronic acid compound on the quantum dot material, further avoid the corrosion of the acidity of the modified quantum dot material to the adjacent transport layer material when the quantum dot material is applied to a device, and improve the stability and service life of the material and the device. On the other hand, through mixing treatment, the ammonia-modified heterocyclic boronic acid compound is connected to the surface of the quantum dot material, and in the heterocyclic boronic acid ligand connected to the surface of the modified quantum dot material, the B atom has strong electron-deficient properties and strong electron attraction ability, which can enhance the electron capture ability of the ligand on the surface of the quantum dot material. In addition, the N and other heterocyclic groups in the heterocyclic boronic acid ligand not only connect the boronic acid compound ligand to the surface of the quantum dot material through the N and other heteroatom sites and the metal atoms such as Zn in the quantum dot material, but also have rich electron clouds, which can efficiently transmit the electrons captured by the boronic acid end to the quantum dot, and improve the efficiency of electron transmission and injection to the quantum dot. The modified quantum dot material of the embodiments of the present application has better electron capture and injection effect and good stability, and has better application prospect in quantum dot light-emitting devices.

[0022] Specifically, in the step S10, the heterocyclic boronic acid compound mainly refers to a boronic acid compound in which one or more hydroxyl / hydrogen atoms are replaced by a heterocyclic group. In some embodiments, the structural formula of the heterocyclic boronic acid compound is selected from: at least one of imidazolyl, pyridyl, quinolyl, indolyl, wherein R1, R2are independently selected from N-containing heterocyclic substituent or hydroxyl; R3, R4are independently selected from N-containing heterocyclic substituent or hydrogen; R5is selected from N-containing heterocyclic substituent. The B atom in the N-containing heterocyclic boronic acid compound of the present application has strong electron-deficient property and strong electron attraction capacity, which can enhance the electron capture capacity of the ligand on the surface of the quantum dot material. Meanwhile, the N-containing heterocyclic substituent connected to the boronic acid can not only connect the boronic acid ligand to the surface of the quantum dot through the N site, but also can efficiently transfer the captured electrons on the boronic acid end to the quantum dot, which is beneficial to the electron transfer from the electron layer to the surface of the quantum dot.

[0023] In some embodiments, the N-containing heterocyclic substituent is at least one of imidazolyl, pyridyl, quinolyl, and indolyl. These N-containing heterocyclic substituents have good coordination effect with both the boronic acid compound and the quantum dot material, which is beneficial to the formation of the modified quantum dot material with the structure of quantum dot material-N-containing heterocyclic substituent-boronic acid compound ligand. In some specific embodiments, the N-containing heterocyclic boronic acid compound is at least one of 5-indole boronic acid, 3-quinoline boronic acid, and 2-pyridine boronic acid.

[0024] In some embodiments, the step of ammonia modification treatment includes: modifying the N-containing heterocyclic boronic acid compound in a mixed gas atmosphere with a temperature of 40-60°C and a volume ratio of ammonia to inert atmosphere of (5-10):(90-95) for 20-60 minutes. In the present application, the N-containing heterocyclic boronic acid compound is modified by ammonia with a volume concentration of 5-10%. The ammonia is combined with the -OH bond on the N-containing heterocyclic boronic acid compound through coordination bond, which passivates the -OH group of the boronic acid compound, making it less likely to be acidic, avoiding the damage of the compound acidity to the adjacent functional layers such as quantum dot material and transport layer, and improving the stability, efficiency and service life of the optoelectronic device. Since the ammonia molecule is a strong electron-accepting group, if the ammonia concentration is too high, the recombination rate of ammonia to the N-containing heterocyclic boronic acid compound will be too high, which will make the ligand have a strong negative charge and reduce the electron-accepting capacity of the ammonia-modified N-containing heterocyclic boronic acid compound. If the ammonia concentration is too low, the modification effect on the N-containing heterocyclic boronic acid compound will be poor. In addition, the modification process is carried out at a temperature of 40-60°C, which can improve the surface modification activity of the compound. However, if the temperature is too high, the boronic acid compound will be deteriorated. In some specific embodiments, the volume ratio of ammonia to inert atmosphere is 5:95, 6:94, 7:93, 8:92, 9:91, 10:90, etc.

[0025] Specifically, in the step S20, the mixing process includes: dissolving the quantum dot material and the ammonia-modified heterocyclic boronic acid compound in an organic solvent in a mass ratio of (90-95):(5-10) to obtain a modified quantum dot material solution. In the present application, the quantum dot material and the ammonia-modified heterocyclic boronic acid compound are directly dissolved in an organic solvent / ink suitable for deposition and mixed sufficiently, so that the ammonia-modified heterocyclic boronic acid compound is coordinated with the quantum dot through the heteroatom in the heterocyclic group, and the surface of the quantum dot material is combined with the ammonia-modified heterocyclic boronic acid ligand. The mass ratio of the quantum dot material to the ammonia-modified heterocyclic boronic acid compound is (90-95):(5-10), and under this ratio, most of the quantum dot surfaces can be connected with the ammonia-modified heterocyclic boronic acid ligand. If the mass ratio of the ammonia-modified heterocyclic boronic acid compound is too high, a large number of other long-chain ligands on the surface of the quantum dot will be replaced / fallen off, thereby affecting the dispersibility of the quantum dot material; if the mass ratio of the ammonia-modified heterocyclic boronic acid compound is too low, the effect of improving electron transport will be affected. In some embodiments, the mass ratio of the ammonia-modified heterocyclic boronic acid compound to the quantum dot material is 5:95, 6:94, 7:93, 8:92, 9:91, 10:90, etc.

[0026] In some embodiments, the organic solvent is selected from at least one of: alkane solvents, halogenated aromatic hydrocarbon solvents, alcohol ether solvents, and alcohol organic solvents. In some specific embodiments, the alkane solvent includes one or more of: n-hexane, cyclohexane, hexane, and n-octane. In some specific embodiments, the halogenated aromatic hydrocarbon 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, and p-bromotoluene. In some specific embodiments, the alcohol ether solvent is one or more of the following: 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 tert-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, and tripropylene glycol butyl ether. In some specific embodiments, the alcoholic organic solvents include n-butanol, isobutanol, sec-butanol, tert-butanol, pentanol, isoamyl alcohol, sec-amyl alcohol, sec-isoamyl alcohol, 3-pentanol, tert-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, and 2-heptanol. The organic solvents used in the above embodiments of this application exhibit good dissolution and dispersion effects on quantum dot materials and ammonia-modified heterocyclic boric acid compounds, which is beneficial for the combination of quantum dot materials and ammonia-modified heterocyclic boric acid compounds to form modified quantum dot materials with ammonia-modified heterocyclic boric acid ligands on their surfaces.

[0027] In some embodiments, the quantum dot material is selected from at least one, or a core-shell structure semiconductor compound composed of at least two elements from Groups II-IV, II-VI, II-V, III-V, III-VI, IV-VI, I-III-VI, II-IV-VI, and II-IV-V of the periodic table. In some specific embodiments, the quantum dot material is selected from at least one binary phase quantum dot from CdS, CdSe, CdTe, InP, AgS, PbS, PbSe, and HgS; or ZnX Cd 1-X S, Cu X In 1-X S, Zn X Cd 1-X Se, Zn X Se 1-X S, Zn X Cd 1-X Te, PbSe X S 1-X at least one ternary phase quantum dot in the group of S, Zn, Cd, In, Se, Te, PbSe, CuInS2, CuInSe2, CuInS2 / ZnS, CdSe / ZnS, CdTe / ZnS, CdSe / ZnSe, CuInSeS, ZnTe / ZnS; or Zn X Cd 1-X S / ZnSe, Cu X In 1-X S / ZnS, Zn X Cd 1-X Se / ZnS, CuInSeS, Zn X Cd 1-X Te / ZnS, PbSe X S 1-X at least one quaternary phase quantum dot in the group of S, Zn, Cd, In, Se, Te, PbSe, CuInS2, CuInSe2, CuInS2 / ZnS, CdSe / ZnS, CdTe / ZnS, CdSe / ZnSe, CuInSeS, ZnTe / ZnS. Each of the above quantum dot materials has the characteristics of quantum dots and good photoelectric performance.

[0028] In some embodiments, the quantum dot material is an oily quantum dot, and a ligand that is easily soluble in a low-polarity solvent is connected to the surface of the quantum dot material. 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, etc. In some specific embodiments, the acid ligand is at least one of decanoic acid, undecylenic acid, tetradecanoic 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.

[0029] 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.

[0030] In some embodiments, the quantum dot material and the ammonia-modified heterocyclic boronic acid compound are dissolved in an organic solvent to obtain a modified quantum dot material solution. The concentration of the modified quantum dot material solution is 1 mg / mL to 200 mg / mL, and is preferably 20 mg / mL to 50 mg / mL. Within this concentration range, the solution processing property of the modified quantum dot material is good, and the dispersibility is good. The modified quantum dot material can be directly deposited into a film through spin coating, spraying, or the like.

[0031] The second aspect of the embodiment of the present application provides a modified quantum dot material, and the surface of the modified quantum dot material is combined with an ammonia-modified heterocyclic boronic acid ligand.

[0032] The surface of the modified quantum dot material provided by the second aspect of the present application is combined with an ammonia-modified heterocyclic boronic acid ligand, wherein the B atom has a strong electron-deficient property and a strong electron attraction capability, and can enhance the electron capture capability of the ligand on the surface of the quantum dot material. The heterocyclic group not only connects the boronic acid compound ligand to the surface of the quantum dot through a heteroatom site, but also has a rich electron cloud, which can efficiently transmit the captured electrons at the boronic acid end to the quantum dot, thereby improving the efficiency of electron transmission and injection into the quantum dot. The amino group is combined with the -OH bond on the heterocyclic boronic acid compound through a coordination bond, thereby protecting the heterocyclic boronic acid compound and avoiding its water absorption and denaturation. In addition, the ammonia modification reduces the acidity of the heterocyclic boronic acid compound, avoids the influence of the acidity on the quantum dot material, and avoids the corrosion of the acidity on the adjacent transmission layer material when the modified quantum dot material is applied to a device, thereby improving the stability and service life of the modified quantum dot material and the device.

[0033] In some embodiments, the ammonia-modified heterocyclic boronic acid ligand is an ammonia-modified N-containing heterocyclic boronic acid ligand, wherein the N heteroatom not only connects the boronic acid ligand to the surface of the quantum dot through an N site, but also has a rich electron cloud, which can efficiently transmit the captured electrons at the boronic acid end to the quantum dot, thereby facilitating the transmission of electrons from the electron layer to the surface of the quantum dot.

[0034] In some embodiments, the mass percentage content of the ammonia-modified heterocyclic boronic acid ligand combined on the surface of the modified quantum dot material is 2% to 10%. This percentage content not only effectively improves the electron capture, transmission and injection effect of the quantum dot material, but also avoids excessive ammonia-modified heterocyclic boronic acid ligand combined on the surface of the quantum dot material, which leads to a large amount of displacement / detachment of other long-chain ligands on the surface of the quantum dot, thereby affecting the dispersibility of the quantum dot material.

[0035] The modified quantum dot material provided by the embodiment of the present application is prepared by the method of the above embodiments.

[0036] The third aspect of the embodiment of the present application provides an optoelectronic device, which contains the quantum dot material modified by the above method or contains the modified quantum dot material.

[0037] The photoelectric device provided in the third aspect of the present application contains the modified quantum dot material with the surface-bound ammonia-modified heterocyclic boronic acid ligand, the modified quantum dot material has high electron capture efficiency, improves the efficiency of electron transmission injection into the quantum dot material, and has good stability. Thus, the photoelectric device provided in the embodiments of the present application has high utilization rate of electrons in the light-emitting layer, effectively improves the recombination effect of carriers in the light-emitting layer, and effectively avoids the influence of charge accumulation on the service life of the device caused by low electron transmission injection efficiency.

[0038] 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.

[0039] In one embodiment, the light-emitting device of positive type structure includes 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 the 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. Figure 2 In some embodiments of the positive type structure, the light-emitting device includes 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.

[0040] In one embodiment, the light-emitting device of reverse type structure includes 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 the 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. Figure 3 In some embodiments of the reverse type structure, the light-emitting device includes 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.

[0041] 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.

[0042] 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 a composite electrode 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.

[0043] 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 materials include, but are 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 oxides include, but are not limited to, one or more of MoO3, VO2, WO3, CrO3, CuO. In some specific embodiments, the metal chalcogenides include, but are not limited to, one or more of MoS2, MoSe2, WS2, WSe2, CuS.

[0044] 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.

[0045] In some embodiments, the light-emitting layer includes the modified quantum dot material described above.

[0046] 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.

[0047] 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.

[0048] In some embodiments, the preparation of the light-emitting device of the embodiments of the present application includes the steps of:

[0049] S30. Obtain a substrate with anode deposited thereon;

[0050] S40. Grow a hole transport layer on the surface of the anode;

[0051] S50. Then deposit a modified quantum dot light emitting layer on the hole transport layer;

[0052] 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.

[0053] Specifically, in step S30, in order to obtain a high-quality light emitting device, the ITO substrate needs to be pre-processed. The basic specific processing 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, deionized water for 20 minutes respectively to remove the impurities present on the surface, and finally blowing dry with high-purity nitrogen, thereby obtaining the ITO anode.

[0054] Specifically, in step S40, the step of growing a hole transport layer includes: on the ITO substrate, depositing a solution of prepared hole transport material into a film through drop coating, spin coating, soaking, coating, printing, evaporation and other processes; controlling the film thickness by adjusting the concentration of the solution, the deposition speed and the deposition time, about 20-60 nm, and then heat annealing at an appropriate temperature.

[0055] Specifically, in step S50, the step of depositing a modified quantum dot light emitting layer on the hole transport layer includes: on the substrate with the hole transport layer deposited thereon, depositing a solution of modified quantum dot material with a certain concentration of surface-bound ammonia-modified heterocyclic boronic acid ligand into a film through drop coating, spin coating, soaking, coating, printing, evaporation and other processes, controlling the thickness of the light emitting layer by adjusting the concentration of the solution, the deposition speed and the deposition time, about 20-60 nm, and drying at an appropriate temperature.

[0056] Specifically, in step S60, the step of depositing an electron transport layer on the quantum dot light emitting layer includes: on the substrate with the quantum dot light emitting layer deposited thereon, depositing a solution of metal oxide transport material with a certain concentration into a film through drop coating, spin coating, soaking, coating, printing, evaporation and other processes, controlling the thickness of the electron transport layer by adjusting the concentration of the solution, the deposition speed (preferably, the rotation speed is between 3000-5000 rpm) and the deposition time, about 20-60 nm, and then annealing into a film at a temperature of 150-200°C to sufficiently remove the solvent.

[0057] Specifically, in step S60, the step of preparing a cathode includes: placing the substrate with the functional layers deposited thereon in an evaporation chamber to evaporate a layer of 15-30 nm of metal silver or aluminum as a cathode through a mask.

[0058] In further embodiments, the obtained QLED device is subjected to encapsulation treatment, which can be machine encapsulation or 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.

[0059] In order to make the above-mentioned implementation details and operations of the present application be clearly understood by those skilled in the art, and the performance of the quantum dot material and the modified method thereof is significantly embodied, the above-mentioned technical solutions are illustrated by multiple embodiments as follows.

[0060] Embodiment 1

[0061] A modified quantum dot material, the preparation steps comprising:

[0062] ① 2-pyridine boronic acid After being placed in 5% ammonia atmosphere (the rest is balanced by argon), heated to 60°C and kept for 30 minutes, the ammoniated 2-pyridine boronic acid is prepared;

[0063] ② The ammoniated 2-pyridine boronic acid is mixed in the green core-shell type CdSe / ZnSe quantum dots at a mass percentage of 5%, and dispersed in n-octane solvent, to prepare a modified quantum dot solution;

[0064] A light-emitting device, the preparation comprising: sequentially spin-coating or depositing a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, an electron transport layer on an ITO substrate, and finally evaporating silver Ag on the electron transport layer to prepare a QLED device. The electron transport layer material is selected from zinc oxide ZnO, with a thickness of 40 nm, the hole transport layer material is selected from TFB, with a thickness of 35 nm, the hole injection layer is selected from PEDOT: PSS material, with a thickness of 10 nm, the cathode material is silver Ag, with a thickness of 20 nm, the anode substrate is an ITO substrate, and the material of the quantum dot light-emitting layer is the modified quantum dot material containing the ammoniated 2-pyridine boronic acid surface ligand prepared in Embodiment 1, with a thickness of 30 nm.

[0065] Embodiment 2

[0066] A modified quantum dot material, which is different from Embodiment 1 in that the heterocyclic boronic acid compound used in step ① is 3-quinoline boronic acid,

[0067] A light-emitting device, which is different from Embodiment 1 in that the material of the quantum dot light-emitting layer is the modified quantum dot material containing the ammoniated 3-quinoline boronic acid surface ligand prepared in Embodiment 2.

[0068] Embodiment 3

[0069] A modified quantum dot material, which is different from example 1 in that the heterocyclic boronic acid compound used in step ① is 5-indole boronic acid;

[0070] A light emitting device, which is different from example 1 in that the material of the quantum dot light emitting layer is the modified quantum dot material containing the aminated 5-indole boronic acid surface ligand prepared in example 3.

[0071] Example 4

[0072] A modified quantum dot material, which is different from example 1 in that the ammonia gas atmosphere used in step ① is 8%.

[0073] A light emitting device, which is different from example 1 in that the material of the quantum dot light emitting layer is the modified quantum dot material containing the aminated 2-pyridine boronic acid surface ligand prepared in example 4.

[0074] Example 5

[0075] A modified quantum dot material, which is different from example 1 in that the ammonia gas atmosphere used in step ① is 10%.

[0076] A light emitting device, which is different from example 1 in that the material of the quantum dot light emitting layer is the modified quantum dot material containing the aminated 2-pyridine boronic acid surface ligand prepared in example 5.

[0077] Example 6

[0078] A modified quantum dot material, which is different from example 1 in that the mass percentage of the aminated 2-pyridine boronic acid used in step ② is 8%.

[0079] A light emitting device, which is different from example 1 in that the material of the quantum dot light emitting layer is the modified quantum dot material containing the aminated 2-pyridine boronic acid surface ligand prepared in example 6.

[0080] Example 7

[0081] A modified quantum dot material, which is different from example 1 in that the mass percentage of the aminated 2-pyridine boronic acid used in step ② is 10%.

[0082] A light emitting device, which is different from example 1 in that the material of the quantum dot light emitting layer is the modified quantum dot material containing the aminated 2-pyridine boronic acid surface ligand prepared in example 7.

[0083] Comparative example 1

[0084] A light emitting device, which is different from example 1 in that the material of the quantum dot light emitting layer is the unmodified green core-shell type CdSe / ZnSe quantum dot material.

[0085] Comparative Example 2

[0086] A modified quantum dot material, which is different from Example 1 in that 2% ammonia atmosphere is used in step ①.

[0087] A light emitting device, which is different from Example 1 in that the material of the quantum dot light emitting layer uses the modified quantum dot material containing the aminated 2-pyridine boronic acid surface ligand prepared in Comparative Example 2.

[0088] Comparative Example 3

[0089] A modified quantum dot material, which is different from Example 1 in that 12% ammonia atmosphere is used in step ①.

[0090] A light emitting device, which is different from Example 1 in that the material of the quantum dot light emitting layer uses the modified quantum dot material containing the aminated 2-pyridine boronic acid surface ligand prepared in Comparative Example 3.

[0091] Comparative Example 4

[0092] A modified quantum dot material, which is different from Example 1 in that the mass percentage of the aminated 2-pyridine boronic acid is 3% in step ②.

[0093] A light emitting device, which is different from Example 1 in that the material of the quantum dot light emitting layer uses the modified quantum dot material containing the aminated 2-pyridine boronic acid surface ligand prepared in Comparative Example 4.

[0094] Comparative Example 5

[0095] A modified quantum dot material, which is different from Example 1 in that the mass percentage of the aminated 2-pyridine boronic acid is 12% in step ②.

[0096] A light emitting device, which is different from Example 1 in that the material of the quantum dot light emitting layer uses the modified quantum dot material containing the aminated 2-pyridine boronic acid surface ligand prepared in Comparative Example 5.

[0097] Further, in order to verify the progressiveness of the embodiments of the present application, the performance of the quantum dot materials and the light emitting devices in Examples 1-7 and Comparative Examples 1-5 is tested as follows.

[0098] (1) Electron mobility: test the current density (J)-voltage (V) of the quantum dot light emitting diode, draw the curve relationship graph, fit the space charge limited current (SCLC) region in the relationship graph, and then calculate the electron mobility according to the famous Child's law formula:

[0099] J=(9 / 8)ε r ε0μe V 2 / d 3 ;

[0100] wherein, J represents current density, unit is mAcm -2 ; ε r represents relative dielectric constant, ε0 represents vacuum dielectric constant; μ e represents electron mobility, unit is cm 2 V -1 s -1 ; V represents driving voltage, unit is V; d represents film thickness, unit is m.

[0101] (2) Resistivity: the resistivity of the QLED device is measured by using the same resistivity testing instrument.

[0102] (3) External quantum efficiency (EQE): the EQE optical testing instrument is used for measurement.

[0103] The test results are shown in Table 1 below:

[0104] Table 1

[0105]

[0106] From the test results in Table 1 above, it can be seen that the resistivity of the light-emitting devices of Examples 1-6 is significantly lower than that of the light-emitting devices of Comparative Examples 1-5, and the electron mobility and external quantum efficiency of the light-emitting devices of Examples 1-6 are significantly higher than those of Comparative Examples 1-5.

[0107] It can be known from the comparison of Examples 1, 4 and 5 with Comparative Examples 2 and 3 that the modification of the heterocyclic boronic acid compound by using too high concentration or too low ammonia is not conducive to improving the electron mobility and external quantum efficiency of the light-emitting device.

[0108] It can be known from the comparison of Examples 1, 6 and 7 with Comparative Examples 4 and 5 that the modification of the quantum dot material by using the heterocyclic boronic acid compound modified by too high or too low proportion of ammonia is not conducive to improving the electron mobility and external quantum efficiency of the light-emitting device.

[0109] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, and 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 method for modifying quantum dot materials, characterized in that, Includes the following steps: A heterocyclic boric acid compound was obtained, and the heterocyclic boric acid compound was subjected to ammonia modification treatment in an ammonia atmosphere with a volume ratio of ammonia to inert atmosphere of (5~10):(90~95) to obtain an ammonia-modified heterocyclic boric acid compound. The heterocyclic boronic acid compound is selected from at least one of the following: 5-indoleboronic acid, 3-quinolineboronic acid, and 2-pyridineboronic acid; To obtain quantum dot material, the quantum dot material in a mass ratio of (90~95):(5~10) is mixed with the ammonia-modified heterocyclic boric acid compound in a solvent to obtain the modified quantum dot material.

2. The method for modifying quantum dot materials as described in claim 1, characterized in that, The ammonia modification process includes: modifying the heterocyclic boric acid compound at a temperature of 40℃~60℃ for 20~60 minutes.

3. The method for modifying quantum dot materials as described in claim 2, characterized in that, The mixing process includes: dissolving the quantum dot material and the ammonia-modified heterocyclic boric acid compound in an organic solvent and mixing them to obtain a modified quantum dot material solution.

4. The method for modifying quantum dot materials as described in claim 3, characterized in that, The organic solvent is selected from at least one of the following: alkane solvents, halogenated aromatic hydrocarbon solvents, alcohol ether solvents, and alcohol organic solvents; And / or, the quantum dot material is selected from at least one of the following semiconductor compounds of Groups II-IV, II-VI, II-V, III-V, III-VI, IV-VI, I-III-VI, II-IV-VI, and II-IV-V of the periodic table, or a core-shell structure semiconductor compound consisting of at least two of them.

5. The method for modifying quantum dot materials according to any one of claims 1 to 4, characterized in that, The quantum dot material is selected from at least one binary phase quantum dot selected from: CdS, CdSe, CdTe, InP, AgS, PbS, PbSe, and HgS; or Zn X Cd 1-X S, Cu X In 1-X S, Zn X Cd 1-X Se、Zn X Se 1-X S, Zn X Cd 1-X Te, PbSe X S 1-X At least one ternary phase quantum dot; or Zn X Cd 1-X S / ZnSe, Cu X In 1-X S / ZnS, Zn X Cd 1-X Se / ZnS, CuInSeS, Zn X Cd 1-X Te / ZnS, PbSe X S 1-X At least one quaternary phase quantum dot in / ZnS; And / or, the surface of the quantum dot material is connected to at least one ligand selected from acid ligands, thiol ligands, amine ligands, phosphophosphine ligands, phospholipids, lecithin, and polyvinylpyridine.

6. A modified quantum dot material prepared by the modification method according to any one of claims 1 to 5, characterized in that, The modified quantum dot material has an ammonia-modified heterocyclic boric acid ligand bonded to its surface.

7. The modified quantum dot material as described in claim 6, characterized in that, The ammonia-modified heterocyclic boric acid ligand is an ammonia-modified N-containing heterocyclic boric acid ligand; And / or, the mass percentage of the ammonia-modified heterocyclic boric acid ligands bound to the surface of the modified quantum dot material is 2% to 10%.

8. An optoelectronic device, characterized in that, The optoelectronic device comprises quantum dot material modified by any of the methods described in claims 1 to 5, or comprises quantum dot material modified by any of the methods described in claims 6 to 7.

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