Quantum dot material and preparation method thereof, photoresist and display device

Abstract

The invention provides a quantum dot material and a preparation method thereof, photoresist and a display device. The quantum dot material provided by the invention comprises a quantum dot, a first organic ligand and a second organic ligand, the first organic ligand and the second organic ligand are respectively connected to the surface of the quantum dot through chemical bonds, the chemical formula of the first ligand is R1-( CR2R3) m-H2PO3, R1 is COOH or COORA, the chemical formula of the second organic ligand is R4-(CR5R6) n-Si (OCH3) 3, and R4 is SH or NH2. According to the quantum dot material provided by the invention, the first organic ligand is introduced to be combined with the surface of the quantum dot to prevent the first organic ligand from falling off after the quantum dot is mixed with blank glue, and the second organic ligand is introduced to be combined with the surface of the quantum dot to passivate cations on the surface of the quantum dot, so that the fluorescence property of the quantum dot is effectively enhanced; and the blue light conversion efficiency of the photoresist is improved.

Description

Technical Field

[0001] This application relates to the field of quantum dot technology, and more specifically, to a quantum dot and its preparation method, photoresist, and display device. Background Technology

[0002] Inorganic quantum dots have attracted widespread attention in the field of display materials due to their narrow half-slit width, tunable light-emitting properties, and high quantum yield. However, since quantum dots are inorganic nanoparticles, their compatibility with most matrix materials is poor. Therefore, an organic ligand layer (i.e., surface ligand) needs to be coordinated on their surface for application. Surface ligands not only stabilize quantum dots but also improve their compatibility with matrix materials, thereby enhancing the optical performance of quantum dot materials.

[0003] Quantum dot photoresist (QDPR) is an advanced photolithography material with high resolution, high sensitivity, and broad spectral response, holding immense potential in nanotechnology and microelectronics manufacturing. It can be used to fabricate high-density integrated circuits, nanodevices, and other micro / nanostructures, including microchips and optical devices. While the advantages of quantum dot photoresist offer broad application prospects, several challenges and limitations exist. The high-temperature heating and UV exposure during photolithography damage the quantum dot surface, leading to a decrease in the fluorescence retention of the quantum dot photoresist film. Furthermore, in some specific applications, the performance of quantum dot photoresist may not meet requirements. For example, when quantum dots are combined with photoresist to form a quantum dot color conversion layer, the use under high-temperature and high-humidity conditions poses a significant challenge to the lifespan of the quantum dots.

[0004] The poor solubility of quantum dots in photoresists has hindered the development of high-resolution display devices. Some researchers have attempted to improve the solubility of quantum dots in photoresists using organic ligands. These ligands include X groups with surfactant properties, A groups with strong hydrophilicity, and Y groups that increase solubility in organic colloids. This allows quantum dots to dissolve effectively in the photoresist, improving the display uniformity of display substrates using quantum dot photoresists and thus obtaining high-performance display substrates and devices. However, during the photolithography process, the surface of the quantum dots cannot be unavoidably damaged by free radicals, leading to a decrease in fluorescence performance. Some researchers use short-chain thiol compounds with unsaturated bond groups as surface ligands. They polymerize these compounds with free radicals and cations decomposed from photoinitiator materials through unsaturated bond groups, or through polymerization reactions between unsaturated bond groups of surface ligands. This avoids direct contact between free radicals and cations and the quantum dot shell, increases the degree of polymer crosslinking on the surface of the quantum dot shell, and forms a stable protective layer on the surface of the quantum dot shell. This ensures the activity of the quantum dot material and improves its stability and optical efficiency. However, the fluorescence retention rate of photoresists containing this quantum dot material is limited under high temperature and high humidity conditions, and its lifetime is difficult to maintain under harsh environments, thus affecting the performance of display devices.

[0005] In view of the above, this application is hereby submitted. Summary of the Invention

[0006] The main objective of this application is to provide a quantum dot material and its preparation method, photoresist, and display device, in order to solve the problem that the existing technology uses ligand modification to improve the solubility of quantum dot materials in photoresist, but this leads to the quantum dot materials being unable to maintain their fluorescence performance or their lifespan under high temperature and high humidity conditions.

[0007] To achieve the above objectives, according to a first aspect of this application, this application provides a quantum dot material comprising a quantum dot, a first organic ligand, and a second organic ligand, wherein the first organic ligand and the second organic ligand are respectively connected to the surface of the quantum dot by chemical bonds; wherein the first organic ligand has the structure shown in formula (I):

[0008] R1 is COOH or COOR A R A It is a C1-C6 alkyl group, m is an integer between 0 and 12, and R2 and R3 are each independently H or C1-C4 alkyl groups;

[0009] The second organic ligand has the structure shown in formula (II):

[0010] R4 is SH or NH2, and n is an integer between 0 and 12; R5 and R6 are each independently H or C1-C4 alkyl.

[0011] Furthermore, R1 can be COOH, COOCH3, COOCH2CH3, or COOCH(CH3)CH3.

[0012] Furthermore, R2 and R3 are independently H and CH3, respectively.

[0013] Furthermore, m is an integer between 1 and 6.

[0014] Furthermore, n is an integer between 1 and 6.

[0015] Furthermore, R5 and R6 are independently H and CH3, respectively.

[0016] Furthermore, the first organic ligand is selected from at least one of 3-phosphopropionic acid, 4-phosphobutyric acid, 2-phosphoacetic acid, and 2-hydroxyphosphoacetic acid.

[0017] Furthermore, the second organic ligand is selected from at least one of 3-mercaptopropyltrimethoxysilane, mercaptopropyltrimethoxysilane, aminopropyltrimethoxysilane, mercaptopropyltriethoxysilane, and aminopropyltriethoxysilane.

[0018] Furthermore, the mass of the first organic ligand is 15%-35% of the mass of the quantum dot.

[0019] Furthermore, the mass of the second organic ligand is 5%-15% of the mass of the quantum dot.

[0020] Furthermore, the quantum dots include at least one of SeS, CdS, CdTe, ZnO, ZnSe, ZnS, ZnTe, ZnSeTe, HgS, HgSe, HgTe, CdZnSe, InAs, InP, InN, GaN, InSb, InAsP, InGaAs, GaAs, GaP, GaSb, AlP, AlN, AlAs, AlSb, CdSeTe, ZnCdS, and CdZnSeS.

[0021] According to a second aspect of this application, this application also provides a method for preparing quantum dot materials, the method comprising: step S1, dispersing quantum dots and a first organic ligand in a first organic solvent for a first modification treatment, such that the first organic ligand is chemically bonded to the surface of the quantum dots to obtain first modified quantum dots; step S2, dispersing the first modified quantum dots and a second organic ligand in a second organic solvent for a second modification treatment, such that the second organic ligand is chemically bonded to the surface of the quantum dots to obtain quantum dot materials; wherein the first organic ligand, the second organic ligand, and the quantum dots are respectively the first organic ligand, the second organic ligand, and the quantum dots provided in the first aspect above, and will not be described again here.

[0022] Furthermore, the amount of the first organic ligand fed is 50%-130% of the mass of the quantum dots.

[0023] Furthermore, the amount of the second organic ligand is 20%-35% of the mass of the first modified quantum dot.

[0024] Furthermore, the first organic solvent is a non-polar organic solvent or a weakly polar organic solvent, preferably selected from at least one of octane, hexane, toluene or m-xylene.

[0025] Furthermore, the second organic solvent is an ether solvent or an ester solvent, preferably selected from at least one of propylene glycol methyl ether, propylene glycol methyl ether acetate, ethylene glycol ethyl ether, ethylene glycol ethyl ether acetate, toluene, or m-xylene.

[0026] According to a third aspect of this application, a photoresist is also provided, which is the quantum dot material provided in the first aspect or the quantum dot material obtained by the preparation method provided in the second aspect.

[0027] According to a fourth aspect of this application, a display device is also provided, the display device comprising a quantum dot material or a photoresist, wherein the quantum dot material is the quantum dot material provided in the first aspect of this application or the quantum dot material obtained according to the preparation method provided in the second aspect of this application, and the photoresist is the photoresist provided in the third aspect of this application.

[0028] By applying the technical solution of this application, the quantum dot material provided by this application, through the introduction of a first organic ligand, utilizes the phosphate group in the first organic ligand to bind with the quantum dot surface, preventing the first organic ligand from falling off after the quantum dots are mixed with blank photoresist. The R1 group (carboxyl or ester group) in the first organic ligand ensures that the quantum dot material is uniformly dispersed in the photoresist, avoiding quantum dot aggregation and improving the display uniformity of the display device using the photoresist. By introducing a second organic ligand, the R4 group (thiol or amino group) in the second organic ligand forms a strong coordination bond with the cations on the quantum dot surface, passivating the cations on the quantum dot surface, effectively enhancing the fluorescence performance of the quantum dots, and improving the blue light conversion efficiency of the photoresist. Simultaneously, the -Si(OCH3)3 group in the second organic ligand hydrolyzes to form a Si-O-Si cross-linked dense network, improving the working stability of the quantum dot material in harsh environments such as high temperature and high humidity, and extending the service life of the photoresist.

[0029] The photoresist provided in this application, by using the aforementioned quantum dot material as raw material, significantly improves the blue light conversion efficiency. The resolution and accuracy of the quantum dot display device using this photoresist are also significantly improved, and the structure and pattern are more refined. Attached Figure Description

[0030] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0031] Figure 1 The image shows a photoresist pattern image prepared from quantum dot material according to Embodiment A-1 of this application; and

[0032] Figure 2 The image shows a photograph of the pattern formed by photolithography on a quantum dot material prepared according to Embodiment A-10 of this application. Detailed Implementation

[0033] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present application will now be described in detail with reference to the embodiments.

[0034] As analyzed in the background section of this application, the poor solubility of quantum dots in photoresists restricts the development of high-resolution display devices. Some researchers have used ligand modification to improve the solubility of quantum dot materials in photoresists, but the photoresists prepared from these ligand-modified quantum dot materials detach during high-temperature baking due to the poor heat resistance of the ligands; furthermore, free radicals generated by photoinitiators under ultraviolet light irradiation can damage the ligands and lead to quantum dot deactivation after contacting unstable groups on the quantum dot surface. In addition, quantum dot photoresists also face some challenges and limitations in display device applications, including the need for a quantum dot color conversion layer formed by combining quantum dots with photoresist, which places higher demands on the lifespan of the quantum dots when used under high temperature and high humidity conditions. To address at least one of these problems, this application provides a quantum dot material, its preparation method, a photoresist, and a display device.

[0035] In a first typical embodiment of this application, a quantum dot material is provided, comprising a quantum dot, a first organic ligand, and a second organic ligand, wherein the first organic ligand and the second organic ligand are respectively connected to the surface of the quantum dot by chemical bonds; wherein the chemical formula of the first organic ligand is R1-(CR2R3). m -H2PO3, with the structure shown in equation (I); R1 is COOH or COOR. A R A The first ligand is a C1-C6 alkyl group, where m is an integer between 0 and 12, and R2 and R3 are each independently H or C1-C4 alkyl groups; the second organic ligand has the chemical formula R4-(CR5R6). n -Si(OCH3)3, as shown in formula (II), where R4 is SH or NH2, and n is an integer between 0 and 12; R5 and R6 are each independently H or C1-C4 alkyl.

[0036]

[0037] In this application, m and n are each independently an integer between 0 and 12, such as 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12.

[0038] R A It is a C1-C6 alkyl group, which includes both straight-chain alkyl groups and branched-chain alkyl groups.

[0039] R2, R3, R5 and R6 are each independently H, a straight-chain alkyl group of C1-C4 or a branched alkyl group of C1-C4.

[0040] In the quantum dot material provided in this application, the phosphorus-oxygen double bond of the phosphate group in the first organic ligand has strong electron-withdrawing properties. It can form stable chemical bonds with metal ions on the quantum dot surface through coordination, replacing the unstable original ligands on the quantum dot surface to form a denser passivation layer. This reduces surface defects, suppresses non-radiative recombination, and improves optical stability. Furthermore, the first organic ligand can utilize the strong electron-withdrawing properties of the phosphorus-oxygen double bond to enhance the quantum dot's resistance to light and heat. During photolithography and subsequent high-temperature, high-blue-light operation, it reduces oxidation or photolysis reactions on the quantum dot surface, thereby extending its lifespan. The R1 group (carboxyl or ester group) of the first organic ligand is an exposed ligand, which allows for better dispersion of the quantum dots in the photoresist, improving the display uniformity of display devices using photoresist. In the second organic ligand, the R4 group (thiol or amino) can passivate the cations on the quantum dot surface, forming strong coordination bonds, effectively enhancing the fluorescence performance of the quantum dots and improving the blue light conversion efficiency of the photoresist. The -Si(OCH3)3 group in the second organic ligand can hydrolyze to generate silanol (Si-OH). The silanol condenses with the hydroxyl (-OH) or adjacent silanol on the quantum dot surface to form a dense Si-O-Si cross-linked network, which makes the second organic ligand firmly attached to the quantum dot surface, effectively preventing the second organic ligand from falling off, thereby improving the working stability of the quantum dot material under harsh conditions such as high temperature and high humidity, and extending the service life of the photoresist.

[0041] Therefore, the quantum dot material provided in this application, by introducing a first organic ligand, utilizes the phosphate group in the first organic ligand to bind with the quantum dot surface, preventing the first organic ligand from falling off after the quantum dots are mixed with blank photoresist. The R1 group (carboxyl or ester group) in the first organic ligand allows the quantum dot material to be uniformly dispersed in the photoresist, avoiding quantum dot aggregation and improving the display uniformity of the display device using the photoresist. By introducing a second organic ligand, the R4 group (thiol or amino group) in the second organic ligand forms a strong coordination bond with the cations on the quantum dot surface, passivating the cations on the quantum dot surface, effectively enhancing the fluorescence performance of the quantum dots, and improving the blue light conversion efficiency of the photoresist. Simultaneously, the Si-O-Si cross-linked dense network formed by the hydrolysis of the -Si(OCH3)3 group in the second organic ligand improves the working stability of the quantum dot material in harsh environments such as high temperature and high humidity, and extends the service life of the photoresist.

[0042] In some embodiments of this application, when R1 is COOH, COOCH3, COOCH2CH3, or COOCH(CH3)CH3, it is more conducive to improving the solubility and dispersion uniformity of quantum dot materials in blank photoresist, avoiding the agglomeration of quantum dot materials, and further improving the display uniformity of photoresist application display devices.

[0043] In some embodiments of this application, when m and n are each an integer between 1 and 6, such as 1, 2, 3, 4, 5, 6, it is more conducive to improving the dispersion stability of quantum dot materials in photoresist and the fluorescence stability under harsh environments.

[0044] In some embodiments of this application, when n is an integer between 1 and 6, such as 1, 2, 3, 4, 5, or 6, it is more conducive to the stable binding of the second organic ligand to the quantum dot surface.

[0045] In some embodiments of this application, R2, R3, R5 and R6 are each independently H and CH3, which is more conducive to improving the binding density of the first organic ligand and the second ligand to the quantum dot surface, and further improving the dispersion uniformity and fluorescence stability of the quantum dot material in the photoresist.

[0046] In some specific embodiments of this application, the first organic ligand is selected from any one or a mixture of 3-phosphopropionic acid, 4-phosphobutyric acid, 2-phosphoacetic acid, and 2-hydroxyphosphoacetic acid to further improve the bonding strength of the chemical bond formed between the first organic ligand and the quantum dot, as well as the solubility of the quantum dot material in the photoresist.

[0047] In some embodiments of this application, the second organic ligand is selected from any one or a mixture of mercaptopropyltrimethoxysilane, aminopropyltrimethoxysilane, mercaptopropyltriethoxysilane, and aminopropyltriethoxysilane, in order to further improve the bonding strength of the chemical bond formed between the second organic ligand and the quantum dot, and further improve the dispersion stability of the quantum dot material in the photoresist and its service life under high temperature and high humidity conditions.

[0048] In some embodiments of this application, the quantum dots are the types of oil-soluble quantum dots commonly used in the art, including but not limited to any one or more of SeS, CdS, CdTe, ZnO, ZnSe, ZnS, ZnTe, ZnSeTe, HgS, HgSe, HgTe, CdZnSe, InAs, InP, InN, GaN, InSb, InAsP, InGaAs, GaAs, GaP, GaSb, AlP, AlN, AlAs, AlSb, CdSeTe, ZnCdS, and CdZnSeS.

[0049] Furthermore, it should be noted that the quantum dots in this application can be of the uniform alloy type, the gradient alloy type, the core-shell type, or the hybrid type, etc.

[0050] In some embodiments of this application, the mass of the first organic ligand is 15%-35% of the mass of the quantum dot, which is beneficial to further improve the solubility of the quantum dot material in the photoresist and the stability of the photoresist containing the quantum dot material during the photolithography process. Specifically, the mass of the first organic ligand is 15%, 18%, 20%, 25%, 30%, 35% of the mass of the quantum dot, or a range of any two of these values.

[0051] In some embodiments of this application, the mass of the second organic ligand is 5%-15% of the quantum dot mass, which helps to further improve the stability of the quantum dot material during photolithography and in harsh environments such as high temperature and high humidity, thereby extending the service life of the quantum dot material in display device applications. Specifically, the mass of the second organic ligand is 5%, 8%, 10%, 12%, 15% of the quantum dot mass or a range of any two values.

[0052] In a second typical embodiment of this application, a method for preparing quantum dots is provided. This method includes: step S1, dispersing quantum dots and a first organic ligand in a first organic solvent for a first modification treatment, such that the first organic ligand is chemically bonded to the surface of the quantum dots, obtaining first modified quantum dots; and step S2, dispersing the first modified quantum dots and a second organic ligand in a second organic solvent for a second modification treatment, such that the second organic ligand is chemically bonded to the surface of the quantum dots, obtaining quantum dot material. The definitions of the first organic ligand, the second organic ligand, and the quantum dots are as described in the first typical embodiment and will not be repeated here.

[0053] The quantum dot material preparation method provided in this application is simple, easy to operate, and easy to scale up for production, thereby further reducing costs.

[0054] In some embodiments of this application, the amount of the first organic ligand is 50%-130% of the quantum dot mass, which facilitates the generation of quantum dot materials with a first organic ligand to quantum dot mass ratio of 15%-35%, thereby further improving the solubility and dispersion stability of the quantum dot material in the photoresist. Specifically, the mass of the first organic ligand is 50%, 60%, 70%, 80%, 90%, 100%, 110%, 120%, 130% of the quantum dot mass, or any combination of two values.

[0055] In some embodiments of this application, the amount of the second organic ligand is 20%-35% of the mass of the first modified quantum dot, which facilitates the preparation of quantum dot materials with a mass ratio of the second organic ligand to the quantum dots of 5%-15%, thereby further improving the stability of the quantum dot material during photolithography and high-temperature and high-humidity operation, and extending the service life of the quantum dot material in display device applications. Specifically, the amount of the second organic ligand is 20%, 22%, 25%, 28%, 30%, 32%, 35% of the quantum dot mass, or any range of two values.

[0056] In some embodiments of this application, the first organic solvent is a nonpolar solvent or a weakly polar solvent to further improve the solubility of the first organic solvent for quantum dots and improve the efficiency of the first modification treatment between the first organic ligand and the quantum dots. Preferably, the first organic solvent is any one or more of octane, hexane, toluene, or m-xylene.

[0057] The second organic solvent mentioned above is a commonly used organic solvent for preparing photoresists, such as a mixture of one or more solvents selected from ether solvents or ester solvents. Ether solvents or ester solvents have stronger solvent polarity, which is more conducive to dispersing the quantum dot material prepared after the second modification, thereby further improving the efficiency of the second modification process. Preferably, the second organic solvent is one or more selected from propylene glycol methyl ether, propylene glycol methyl ether acetate, ethylene glycol ethyl ether, and ethylene glycol ethyl ether acetate.

[0058] In some specific embodiments, the first organic solvent is any one or more of octane, toluene, and hexane to further improve the efficiency of the first modification treatment; the second organic solvent is any one or more of propylene glycol methyl ether, propylene glycol methyl ether acetate, ethylene glycol ethyl ether, and ethylene glycol ethyl ether acetate to further improve the efficiency of the second modification treatment.

[0059] It should be noted that the first and second organic solvents mentioned above only need to have a difference in polarity to achieve the dissolution and separation effect; the specific types can be the same or different.

[0060] In some embodiments of this application, the preparation method of quantum dot materials includes:

[0061] Step S1: Disperse quantum dots in a first organic solvent to form a quantum dot solution; add a first organic ligand to the quantum dot solution and perform a first ultrasonic treatment to obtain a first modified quantum dot reaction solution; separate the first quantum dot reaction solution into solid and liquid phases to obtain a first solid; disperse the first solid in a first antisolvent to obtain a first antisolvent solution of the first modified quantum dots; add a first organic solvent to the first antisolvent solution of the first modified quantum dots and centrifuge to purify it to obtain a second solid; dry the second solid to obtain the first modified quantum dots.

[0062] In step S2, the first modified quantum dots are dispersed in the second organic solvent to form a first modified quantum dot solution. The second organic ligand is added to the first modified quantum dot solution for a second ultrasonic treatment to obtain a second modified quantum dot reaction solution. The second antisolvent is added to the second modified quantum dot reaction solution for centrifugal purification. The resulting precipitate is dried to obtain the quantum dot material.

[0063] The first antisolvent mentioned above refers to a solvent with a polarity that is significantly different from or opposite to that of the first organic solvent; the second antisolvent mentioned above refers to a solvent with a polarity that is significantly different from or opposite to that of the second organic solvent.

[0064] In some embodiments of this application, solvents with relatively strong polarity, such as ethanol or propylene glycol methyl ether, are selected as the first antisolvent. This is because the polarity of the quantum dots increases after the first organic ligands are bound to the surface to form the first modified quantum dots, resulting in decreased solubility in the first organic solvent. Therefore, the first antisolvent is added to dissolve the first modified quantum dots, precipitating and removing the quantum dots that are not sufficiently bound and still have relatively weak polarity, thereby achieving the purpose of purifying the first modified quantum dots.

[0065] In some embodiments of this application, the second antisolvent has the opposite polarity to the second solvent. Generally, a nonpolar or weakly polar solvent is chosen as the second antisolvent, such as toluene, hexane, or octane. By utilizing the polarity difference between the second antisolvent and the second organic solvent, the quantum dot material modified with both the first and second organic ligands (which is more polar) is separated by precipitation using a weakly polar or nonpolar solvent. Meanwhile, the first modified quantum dots, which do not bind the second organic ligand, dissolve in the second organic solvent, thereby achieving the purpose of purifying the quantum dot material.

[0066] In a third typical embodiment of this application, a photoresist is also provided, which includes the quantum dot material provided in the first typical embodiment or the quantum dot material obtained according to the method provided in the second typical embodiment.

[0067] The photoresist provided in this application uses quantum dots with first and second organic ligands chemically bonded to their surface as quantum dot materials. This not only avoids free radical damage caused by exposure during photolithography, resulting in display devices with higher resolution and precision, and the creation of finer structures and patterns, but also enhances the stability of the photoresist in harsh environments such as high temperature and high humidity, greatly extending the fluorescence retention time and thus extending the lifespan of display devices using the photoresist.

[0068] In a fourth typical embodiment of this application, a display device is also provided, which includes a quantum dot material or a photoresist, wherein the quantum dot material is the quantum dot material provided in the first typical embodiment or the quantum dot material obtained according to the method provided in the second typical embodiment; and the photoresist is the photoresist provided in the third typical embodiment.

[0069] The display device provided in this application uses quantum dot materials or photoresists containing quantum dot materials, which include the above-mentioned quantum dot surface chemical bonds connecting the first organic ligand and the second organic ligand. This not only avoids the damage of free radicals to the photoresist during exposure, improving the resolution and accuracy of the display device and creating finer structures and patterns, but also enhances the stability of the photoresist in harsh environments such as high temperature and high humidity, greatly extending the fluorescence retention time and effectively extending the service life of the display device.

[0070] The beneficial effects of this application will be further illustrated below with reference to embodiments and comparative examples.

[0071] (I) The quantum dots are oil-soluble core-shell structured CdSe / ZnS quantum dots (wavelength 625nm, peak width 30nm, red).

[0072] Example A-1

[0073] This embodiment provides a quantum dot material, which is prepared according to the following steps.

[0074] (1) 1g of oil-soluble CdSe / ZnS quantum dots with a core-shell structure was dispersed in 20mL of toluene, a first organic solvent, to obtain a quantum dot suspension. 1g of the first organic ligand, 3-phosphopropionic acid, was added to the quantum dot solution and ultrasonically stirred for 1h at room temperature to obtain a first modified quantum dot reaction solution. The first modified quantum dot reaction solution was purified by centrifugation to obtain a first solid. The first solid was dispersed in 20mL of ethanol, a first antisolvent, and then purified by centrifugation to remove the precipitate, to obtain an ethanol solution of the first modified quantum dots. 20mL of toluene, the first organic solvent, was added to the ethanol solution of the first modified quantum dots, and the mixture was purified by centrifugation to obtain a second solid. The second solid was dried to obtain the first modified quantum dots.

[0075] (2) 1g of the first modified quantum dots were dispersed in 20mL of the second organic solvent propylene glycol methyl ether to form a first modified quantum dot solution. 0.25g of the second organic ligand 3-mercaptopropyltrimethoxysilane was added to the first modified quantum dot solution, and the mixture was ultrasonically stirred for 30min at room temperature to obtain a second modified quantum dot reaction solution. 20mL of the second antisolvent toluene was added to the second modified quantum dot reaction solution, and the mixture was centrifuged for purification. The resulting precipitate was dried to obtain the quantum dot material.

[0076] Example A-2

[0077] The difference between this embodiment and embodiment A-1 is that in step (1), the amount of the first organic ligand 3-phosphopropionic acid is 0.5g.

[0078] Example A-3

[0079] The difference between this embodiment and embodiment A-1 is that in step (1), the amount of the first organic ligand 3-phosphopropionic acid is 1.3g.

[0080] Example A-4

[0081] The difference between this embodiment and embodiment A-1 is that in step (1), the amount of the first organic ligand 3-phosphopropionic acid is 0.2g.

[0082] Example A-5

[0083] The difference between this embodiment and embodiment A-1 is that in step (1), the amount of the first organic ligand 3-phosphopropionic acid is 1.5g.

[0084] Example A-6

[0085] The difference between this embodiment and embodiment A-1 is that in step (2), the amount of the second organic ligand 3-mercaptopropyltrimethoxysilane is 0.2g.

[0086] Example A-7

[0087] The difference between this embodiment and embodiment A-1 is that in step (2), the amount of the second organic ligand 3-mercaptopropyltrimethoxysilane is 0.35g.

[0088] Example A-8

[0089] The difference between this embodiment and embodiment A-1 is that in step (2), the amount of the second organic ligand 3-mercaptopropyltrimethoxysilane is 0.08g.

[0090] Example A-9

[0091] The difference between this embodiment and embodiment A-1 is that in step (2), the amount of the second organic ligand 3-mercaptopropyltrimethoxysilane is 0.50g.

[0092] Example A-10

[0093] The difference between this embodiment and embodiment A-1 is that, in step (1), the amount of the first organic ligand 3-phosphopropionic acid is 0.2g; and in step (2), the amount of the second organic ligand 3-mercaptopropyltrimethoxysilane is 0.15g.

[0094] Example A-11

[0095] The difference between this embodiment and embodiment A-1 is that, in step (1), the amount of the first organic ligand 3-phosphopropionic acid is 1.5g; and in step (2), the amount of the second organic ligand 3-mercaptopropyltrimethoxysilane is 0.4g.

[0096] Comparative Example A-1

[0097] This comparative example is an oil-soluble quantum dot CdSe / ZnS with a core-shell structure.

[0098] Comparative Example A-2

[0099] This comparative example is the first modified quantum dot obtained in step (1) of Example A-1.

[0100] Comparative Example A-3

[0101] The quantum dot material provided in this comparative example was prepared according to the following steps: 1 g of oil-soluble CdSe / ZnS quantum dots with a core-shell structure was dispersed in 20 mL of propylene glycol methyl ether to obtain a quantum dot suspension. 0.25 g of the second organic ligand, 3-mercaptopropyltrimethoxysilane, was added to the quantum dot suspension, and the mixture was ultrasonically stirred at room temperature for 30 min to obtain a modified quantum dot reaction solution. 20 mL of toluene was added to the modified quantum dot reaction solution, and the mixture was then centrifuged to purify it. The resulting precipitate was the quantum dot material.

[0102] Experimental Example 1

[0103] The contents of the first organic ligand and the second organic ligand in the quantum dot materials provided in the above embodiments and comparative examples were detected, and the results are shown in Table 1 below. Specifically, the phosphorus, sulfur, and silicon contents of the quantum dot materials were detected using ICP-OES. The content of the first organic ligand was calculated based on the phosphorus content, and the content of the second organic ligand was calculated based on the sulfur and silicon contents.

[0104] The quantum yields of the quantum dot materials provided in the above embodiments and comparative examples were tested respectively, and the results are shown in Table 1 below. The quantum yields were tested according to GB / T 37664.1.

[0105] The quantum dot materials provided in the above examples and comparative examples were used to prepare photoresists, and the quantum yield of the photoresists was tested. The results are shown in Table 1 below. The specific composition of the photoresist is as follows: by mass fraction, 5% quantum dot material, 15% polymethyl methacrylate, 2% photoinitiator 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), and 78% solvent propylene glycol methyl ether acetate. The preparation method is as follows: according to the above ratio, polymethyl methacrylate is added to propylene glycol methyl ether acetate (PGMEA), and stirred thoroughly until completely dissolved to obtain a resin solution. Quantum dot material is then added to the resin solution, and the mixture is continuously stirred and ultrasonically treated to ensure that the quantum dot material is fully dispersed. Finally, the photoinitiator TPO pre-dissolved in propylene glycol methyl ether acetate is added, and the mixture is thoroughly mixed. Undispersed particles and impurities are removed using a polytetrafluoroethylene filter membrane with a pore size of 0.22 μm to obtain the photoresist.

[0106] Quantum dot films were prepared using photoresists made from the quantum dot materials provided in the above examples and comparative examples. The quantum dot yield of the quantum dot films was measured, and the results are shown in Table 1. The preparation method of the quantum dot films was as follows: the glass substrate was pretreated by ultrasonic cleaning with acetone and isopropanol for 10 min each, drying with nitrogen, and then drying at 120°C for 30 min; the photoresist was uniformly coated onto the substrate by spin coating; the substrate was baked at 100°C for 15 min to remove the PGMEA (propylene glycol methyl ether acetate) solvent; the substrate was heat-cured at 180°C for 20 min and then naturally cooled to room temperature to obtain a quantum dot film with a thickness of 100 μm.

[0107] The quantum dot films were subjected to aging treatment. The specific aging treatment steps were as follows: aging at 85% humidity and 85℃ for 500 hours, and the quantum yield of the quantum dot films after aging treatment was detected. The results are shown in Table 1.

[0108] The photoresists prepared from the quantum dot materials provided in the examples and comparative examples were patterned using photolithography, and the photolithography accuracy was tested. Then, the quantum yield of the photolithographically patterned quantum dot films was measured, and the results are shown in Table 1 below. The photolithography accuracy was tested by observing and measuring the morphology and size of the photolithographic dot array using an optical microscope.

[0109] Table 1

[0110]

[0111] Note: (1) No ligands were added in the above comparative example A-1, so it could not be dispersed in the blank photoresist to form photoresist. Therefore, the yield of photoresist, quantum dot film, quantum dot film after aging and the precision of photoresist were not tested.

[0112] (2) In the above comparative example A-3, only the second organic ligand was added, and the dispersion was very poor. It was impossible to prepare a photoresist with uniform dispersion of quantum dot material. Therefore, the yield of quantum dot film, quantum dot film after aging and the precision of photoresist were not tested.

[0113] Figure 1 This is a photograph of the photoresist pattern prepared from the quantum dot material provided in Embodiment A-1 of this application. Figure 1 It can be seen that the precision of the photoresist pattern prepared from the quantum dot material provided in Example A-1 is 4 μm.

[0114] Figure 2 This is a photograph of the photoresist pattern prepared from quantum dot material according to Embodiment A-10 of this application. Figure 2 It can be seen that the precision of the photoresist pattern prepared from the quantum dot material provided in Example A-10 is 25 μm.

[0115] As can be seen from the comparison of Examples A-1 to A-3, A-6, and A-7 with Examples A-4, A-5, A-8 to A-11 in Table 1, in quantum dot materials, the mass of the first organic ligand is 15%-35% of the mass of the quantum dot, and the mass of the second organic ligand is 5%-15% of the mass of the quantum dot. The photoresist prepared by this material has higher stability and higher photolithography precision under harsh conditions such as high temperature and high humidity.

[0116] The comparison between Examples A-1 to A-3, Example A-6, Example A-7 and Comparative Example A-2 shows that introducing a second organic ligand into quantum dot materials is more conducive to improving their stability under high temperature and high humidity environments.

[0117] (ii) The quantum dots are oil-soluble core-shell structured CdSeS / ZnS (wavelength 525nm, peak width 31nm, green).

[0118] Example B-1

[0119] The difference between Example B-1 and Example A-1 is that the oil-soluble core-shell structured oil-soluble quantum dots CdSe / ZnS are replaced with oil-soluble core-shell structured oil-soluble quantum dots CdSeS / ZnS.

[0120] Example B-2

[0121] The difference between Example B-2 and Example A-10 is that the oil-soluble core-shell structured oil-soluble quantum dots CdSe / ZnS are replaced with oil-soluble core-shell structured oil-soluble quantum dots CdSeS / ZnS.

[0122] Example B-3

[0123] The difference between Example B-3 and Example A-11 is that the oil-soluble core-shell structured oil-soluble quantum dots CdSe / ZnS are replaced with oil-soluble core-shell structured oil-soluble quantum dots CdSeS / ZnS.

[0124] The contents of the first organic ligand and the second organic ligand in the quantum dot material provided in the above embodiments were detected, and the results are shown in Table 2 below.

[0125] The quantum yields of the quantum dot materials provided in the above embodiments and comparative examples were tested respectively, and the results are shown in Table 2 below.

[0126] The quantum dot materials provided in the above embodiments and comparative examples were used to prepare photoresists. The preparation method of the photoresists was the same as that in Experimental Example 1. The quantum yield of the above photoresists was tested, and the results are shown in Table 2 below.

[0127] Quantum dot films were prepared from photoresists made from the quantum dot materials provided in the above embodiments and comparative examples. The quantum yield of the quantum dot films was measured, and then the quantum dot films were subjected to aging treatment, specifically the same as in Experimental Example 1. The quantum yield of the quantum dot films after aging treatment was measured, and the results are shown in Table 2.

[0128] The quantum dot films before aging were subjected to photolithography precision testing, and then the quantum dot films after photolithography were subjected to quantum yield testing. The results are shown in Table 2 below.

[0129] Table 2

[0130]

[0131]

[0132] As can be seen from the comparison of Examples B-1, B-2, and B-3 in Table 2, in quantum dot materials, the mass of the first organic ligand is 15%-35% of the mass of the quantum dot, and the mass of the second organic ligand is 5%-15% of the mass of the quantum dot. The photoresist prepared by this material has higher stability and higher photolithography precision under harsh conditions such as high temperature and high humidity.

[0133] (III) The quantum dots are oil-soluble red InP / ZnSe / ZnS quantum dots with an oil-soluble core-shell structure (wavelength 620nm, peak width 36nm, red).

[0134] Example C-1

[0135] The difference between Example C-1 and Example A-1 is that the oil-soluble core-shell structured oil-soluble quantum dots CdSe / ZnS are replaced with oil-soluble core-shell structured oil-soluble red quantum dots InP / ZnSe / ZnS, and in step (1), the amount of the first organic ligand 3-phosphopropionic acid is 0.7g; in step (2), the amount of the second organic ligand 3-mercaptopropyltrimethoxysilane is 0.3g.

[0136] Example C-2

[0137] The difference between Example C-2 and Example A-10 is that the oil-soluble core-shell structured oil-soluble quantum dots CdSe / ZnS are replaced with oil-soluble core-shell structured oil-soluble red quantum dots InP / ZnSe / ZnS. In step (1), the amount of the first organic ligand 3-phosphopropionic acid is 0.15 g; in step (2), the amount of the second organic ligand 3-mercaptopropyltrimethoxysilane is 0.1 g.

[0138] Example C-3

[0139] The difference between Example C-3 and Example A-11 is that the oil-soluble core-shell structured oil-soluble quantum dots CdSe / ZnS are replaced with oil-soluble core-shell structured oil-soluble red quantum dots InP / ZnSe / ZnS. In step (1), the amount of the first organic ligand 3-phosphopropionic acid is 1.1 g; in step (2), the amount of the second organic ligand 3-mercaptopropyltrimethoxysilane is 0.45 g.

[0140] The contents of the first organic ligand and the second organic ligand in the quantum dot material provided in the above embodiments were detected, and the results are shown in Table 3 below.

[0141] The quantum yield of the quantum dot materials provided in the above embodiments was tested, and the results are shown in Table 3 below.

[0142] The quantum dot material provided in the above embodiments was used to prepare photoresist. The preparation method of the photoresist was the same as that in Experimental Example 1. The quantum yield of the above photoresist was tested, and the results are shown in Table 3 below.

[0143] The photoresist prepared from the quantum dot material provided in the above embodiments was used to prepare quantum dot films. The quantum yield of the quantum dot films was then tested. The quantum dot films were then subjected to aging treatment. The aging treatment steps were as follows: aging at 60% humidity and 60°C for 500 hours. The quantum yield of the quantum dot films after aging treatment was tested. The results are shown in Table 3.

[0144] The quantum dot films before aging were subjected to photolithography precision testing, and then the quantum dot films after photolithography were subjected to quantum yield testing. The results are shown in Table 3 below.

[0145] Table 3

[0146]

[0147] As can be seen from the comparison of Examples C-1, C-2, and C-3 in Table 3, in quantum dot materials, the mass of the first organic ligand is 15%-35% of the mass of the quantum dot, and the mass of the second organic ligand is 5%-15% of the mass of the quantum dot. The photoresist prepared by this material has higher stability and higher photolithography precision under harsh conditions such as high temperature and high humidity.

[0148] (iv) The quantum dots are oil-soluble core-shell structured InP / ZnSe / ZnS quantum dots (wavelength 530nm, peak width 37nm, green).

[0149] Example D-1

[0150] The difference between Example D-1 and Example A-1 is that the oil-soluble core-shell structured oil-soluble quantum dots CdSe / ZnS are replaced with oil-soluble core-shell structured oil-soluble green quantum dots InP / ZnSe / ZnS; and in step (1), the amount of the first organic ligand 3-phosphopropionic acid is 0.7g; and in step (2), the amount of the second organic ligand 3-mercaptopropyltrimethoxysilane is 0.3g.

[0151] Example D-2

[0152] The difference between Example D-2 and Example A-10 is that the oil-soluble core-shell structured oil-soluble quantum dots CdSe / ZnS are replaced with oil-soluble core-shell structured oil-soluble green quantum dots InP / ZnSe / ZnS; and in step (1), the amount of the first organic ligand 3-phosphopropionic acid is 0.15g; and in step (2), the amount of the second organic ligand 3-mercaptopropyltrimethoxysilane is 0.1g.

[0153] Example D-3

[0154] The difference between Example D-3 and Example A-11 is that the oil-soluble core-shell structured oil-soluble quantum dots CdSe / ZnS are replaced with oil-soluble core-shell structured oil-soluble green quantum dots InP / ZnSe / ZnS; and in step (1), the amount of the first organic ligand 3-phosphopropionic acid is 1.1 g; and in step (2), the amount of the second organic ligand 3-mercaptopropyltrimethoxysilane is 0.45 g.

[0155] The contents of the first organic ligand and the second organic ligand in the quantum dot material provided in the above embodiments were detected, and the results are shown in Table 4 below.

[0156] The quantum yield of the quantum dot materials provided in the above embodiments was tested, and the results are shown in Table 4 below.

[0157] The quantum dot material provided in the above embodiments was used to prepare photoresist. The preparation method of the photoresist was the same as that in Experimental Example 1. The quantum yield of the above photoresist was tested, and the results are shown in Table 4 below.

[0158] The photoresist prepared from the quantum dot material provided in the above embodiments was used to prepare quantum dot films, and the quantum yield of the quantum dot films was tested respectively. The results are shown in Table 4 below.

[0159] The quantum dot films were subjected to aging treatment. The specific aging treatment steps were as follows: aging at 60% humidity and 60℃ for 500 hours, and the quantum yield of the quantum dot films after aging treatment was detected. The results are shown in Table 4.

[0160] The quantum dot films before aging were subjected to photolithography precision testing, and then the quantum dot films after photolithography were subjected to quantum yield testing. The results are shown in Table 4 below.

[0161] Table 4

[0162]

[0163] As can be seen from the comparison of Examples D-1, D-2, and D-3 in Table 4, in quantum dot materials, the mass of the first organic ligand is 15%-35% of the mass of the quantum dot, and the mass of the second organic ligand is 5%-15% of the mass of the quantum dot. The photoresist prepared by this material has higher stability and higher photolithography precision under harsh conditions such as high temperature and high humidity.

[0164] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A quantum dot material, characterized in that, The quantum dot material includes quantum dots, a first organic ligand, and a second organic ligand, wherein the first organic ligand and the second organic ligand are respectively connected to the surface of the quantum dots by chemical bonds; The first organic ligand has the structure shown in formula (I): R1 is COOH or COOR A R A It is a C1-C6 alkyl group, m is an integer between 0 and 12, and R2 and R3 are each independently H or C1-C4 alkyl groups; The second organic ligand has the structure shown in formula (II): R4 is SH or NH2, and n is an integer between 0 and 12; R5 and R6 are each independently H or C1-C4 alkyl.

2. The quantum dot material according to claim 1, characterized in that, R1 is COOH, COOCH3, COOCH2CH3, COOCH(CH3)CH3; And / or, R2 and R3 are each independently H and CH3; And / or, m is an integer between 1 and 6; And / or, n is an integer between 1 and 6; And / or, R5 and R6 are each independently H and CH3.

3. The quantum dot material according to claim 1, characterized in that, The first organic ligand is selected from at least one of 3-phosphoproteomic acid, 4-phosphoproteomic acid, 2-phosphoproteoacetic acid, and 2-hydroxyphosphorylated acetic acid; And / or, the second organic ligand is selected from at least one of 3-mercaptopropyltrimethoxysilane, mercaptopropyltrimethoxysilane, aminopropyltrimethoxysilane, mercaptopropyltriethoxysilane, and aminopropyltriethoxysilane.

4. The quantum dot material according to claim 1, characterized in that, The mass of the first organic ligand is 15%-35% of the mass of the quantum dot; And / or, the mass of the second organic ligand is 5%-15% of the mass of the quantum dot.

5. The quantum dot material according to any one of claims 1 to 4, characterized in that, The quantum dots are oil-soluble quantum dots, and the quantum dots include at least one of SeS, CdS, CdTe, ZnO, ZnSe, ZnS, ZnTe, ZnSeTe, HgS, HgSe, HgTe, CdZnSe, InAs, InP, InN, GaN, InSb, InAsP, InGaAs, GaAs, GaP, GaSb, AlP, AlN, AlAs, AlSb, CdSeTe, ZnCdS, and CdZnSeS.

6. A method for preparing quantum dot materials, characterized in that, The preparation method includes: Step S1: The quantum dots and the first organic ligand are dispersed in a first organic solvent for a first modification treatment, so that the first organic ligand is chemically bonded to the surface of the quantum dots to obtain the first modified quantum dots; Step S2: The first modified quantum dot and the second organic ligand are dispersed in a second organic solvent for a second modification treatment, so that the second organic ligand is chemically bonded to the surface of the quantum dot to obtain the quantum dot material; Wherein, the first organic ligand is the first organic ligand as described in any one of claims 1 to 5; the second organic ligand is the second organic ligand as described in any one of claims 1 to 5; and the quantum dot is the quantum dot as described in any one of claims 1 to 5.

7. The preparation method according to claim 6, characterized in that, The amount of the first organic ligand fed is 50%-130% of the mass of the quantum dots; And / or, the amount of the second organic ligand fed is 20%-35% of the mass of the first modified quantum dot.

8. The preparation method according to claim 6, characterized in that, The first organic solvent is a non-polar organic solvent or a weakly polar organic solvent, preferably selected from at least one of octane, hexane, toluene, and m-xylene; And / or, the second organic solvent is an ether solvent or an ester solvent, preferably selected from at least one of propylene glycol methyl ether, propylene glycol methyl ether acetate, ethylene glycol ethyl ether, and ethylene glycol ethyl ether acetate.

9. A photoresist, characterized in that, The photoresist comprises the quantum dot material according to any one of claims 1 to 5 or the quantum dot material obtained by the preparation method according to any one of claims 6 to 8.

10. A display device, characterized in that, The display device includes quantum dot material or photoresist, wherein the quantum dot material is the quantum dot material according to any one of claims 1 to 5 or the quantum dot material obtained by the preparation method according to any one of claims 6 to 8, and the photoresist is the photoresist according to claim 9.

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