Preparation method of quantum dot dispersion liquid and application of quantum dot dispersion liquid in photoetching patterning

Abstract

The invention discloses a preparation method of quantum dot dispersion liquid and application of the quantum dot dispersion liquid in photoetching patterning, and belongs to the technical field of display. The preparation method of the quantum dot dispersion liquid comprises the following steps: mixing quantum dots, modified PEG and a photoresist solvent, reacting, and adding a second ligand to continuously react to obtain the quantum dot dispersion liquid, the modified PEG contains groups which have interaction force with the surfaces of the quantum dots, and the groups comprise one of coordination action, hydrogen bond action and Van der Waals force action; the second ligand contains a coordination group and an acidic group, and the acidic group is selected from one of carboxyl, phenolic hydroxyl, sulfonic group and sulfydryl. According to the method, high-concentration, high-PLQY and stable dispersion of the quantum dots in photoresist solvents such as PGMEA and the like can be realized; the method is simple, and subsequent cleaning work is not needed; the acid value of the quantum dot dispersion liquid can be adjusted by adding the second ligand and introducing the acidic ligand to be matched with the modified PEG, so that the quantum dot dispersion liquid can be developed cleanly without residues in subsequent photoetching.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of a quantum dot dispersion liquid and application thereof in photoetching patterning, and belongs to the technical field of display. BACKGROUND

[0002] The quantum dot photoetching technology comprises the following steps: mixing of quantum dots and photoresist, spin coating, pre-baking, exposure, post-baking, development and the like, wherein the development process is mainly realized by using an alkaline aqueous solution. At present, quantum dots are mostly obtained by using a hot injection method, and the long fatty chain ligand on the surface of the quantum dots has strong dispersing capacity in a non-polar solvent. However, the solvent used by the photoresist is mostly an ester or alcohol ether solvent such as propylene glycol methyl ether acetate (PGMEA), and the polarity of the solvent makes the quantum dots obtained by the hot injection method unable to be well dispersed in the solvent. The polarity of the ligand on the surface of the quantum dots can be adjusted by ligand modification, and the dispersing degree of the quantum dots in the solvent of the photoresist is improved, so that the uniformity and resolution of the photoetching pattern are improved.

[0003] At present, the surface modification ligand of the quantum dots suitable for the photoresist is mainly modified PEG. The segment structure of -CH2-CH2-O- in the PEG can provide suitable solubility for the quantum dots, and the action capacity of the polymer and the quantum dots can be improved by capping the two ends or one end of the PEG molecule through the coordination group of the quantum dots, so that the dispersing degree of the quantum dots in PGMEA is improved. However, the modified PEG modified quantum dots have the following problems: first, the single modified PEG modification cannot meet the demand of alkaline development in the actual photoetching process, and a complete and clear pattern cannot be obtained; second, the modified solution is mostly carried out in a non-polar solution such as toluene, and the subsequent cleaning and purification process may have a negative impact on the optical performance of the quantum dots, in addition, the cleaning process is relatively complex and the organic solvent used in the process is not friendly to the environment; third, when the modified solution directly uses PGMEA, a solvothermal method is usually used, and the process needs to be carried out at high temperature and high pressure, the reaction time is relatively long, and there is a certain risk. SUMMARY

[0004] In view of the above problems, the application provides a preparation method of a quantum dot dispersion liquid and application thereof in photoetching patterning. The modified PEG and the second ligand are used in coordination in the application, wherein the modified PEG provides dispersing property, and the second ligand can adjust the acid value of the quantum dot dispersion liquid, so that the quantum dot dispersion liquid can be developed by using an alkaline aqueous solution in the patterning process. The quantum dots, the ligand, PGMEA and the like are directly mixed at a certain temperature, and the required quantum dot dispersion liquid can be obtained. The method is simple, and can be directly applied to photoetching patterning without subsequent cleaning work. The photoetching pattern obtained by using the quantum dot dispersion liquid prepared by using the application is developed cleanly and has high resolution.

[0005] According to the first aspect of this application, a method for preparing a quantum dot dispersion is provided. The dispersion is obtained by mixing and stirring solutions of quantum dots, ligands, and PGMEA at a certain temperature. The ligands include modified PEG and a second ligand. The modified PEG comprises a main chain segment structure of PEG, with one end of the molecular chain capped by a coordinating group and the other end capped by other groups. The PEG chain segment structure provides dispersibility, and the coordinating group interacts with the surface of the quantum dots. The second ligand contains a coordinating group and an acidic group. The acidic group allows the photolithographic pattern to be thoroughly developed using an alkaline developer, resulting in a clear and clean photolithographic pattern. Furthermore, through the coordinated combination of ligands with different molecular weights, high concentration, high PLQY, and stable dispersion of quantum dots in PGMEA can be achieved.

[0006] A method for preparing a quantum dot dispersion involves mixing quantum dots, modified PEG, and a photoresist solvent, reacting the mixture, adding a second ligand, and continuing the reaction to obtain the quantum dot dispersion.

[0007] The modified PEG is B-PEG-A, with the following structural formula:

[0008]

[0009] The structural formula of the second ligand is as follows:

[0010]

[0011] Wherein, A is an independent group that interacts with the surface of the quantum dot, including one of coordination interaction, hydrogen bonding interaction, and van der Waals force interaction;

[0012] B is the PEG end-capping group, which does not interact with the quantum dots;

[0013] X is a group that interacts with a basic group, selected from one of the following: carboxyl, phenolic hydroxyl, sulfonic acid, and mercapto groups;

[0014] Y is the backbone structure connecting A and X, including one of C2-C18 long-chain aliphatic alkanes, C2-C18 long-chain aliphatic alkenes, and PEG structures;

[0015] The modified PEG has a molecular weight of 200-10000.

[0016] Optionally, the mass ratio of the quantum dots to the modified PEG is 1:0.1-2.

[0017] Optionally, the mass ratio of the quantum dots to the modified PEG is independently any value from 1:0.1, 1:0.2, 1:0.5, 1:0.7, 1:1, 1:1.1, 1:1.2, 1:1.5, 1:1.7, 1:2 or any range between the two.

[0018] Optionally, the mass ratio of the quantum dot to the photoresist solvent is 1:2-20.

[0019] Optionally, when it is a coordination reaction, A is selected from one of mercapto, carboxyl, amino, organophosphine, organophosphine oxide, and sulfonic acid groups;

[0020] When hydrogen bonding occurs, A is selected from hydroxyl groups;

[0021] When van der Waals forces are involved, A is selected from one of C2-C18 long-chain aliphatic alkanes and C2-C18 long-chain aliphatic olefins.

[0022] Preferably, when van der Waals forces are involved, A is selected from one of C8-C12 long-chain aliphatic alkanes and C8-C12 long-chain aliphatic olefins.

[0023] Optionally, B is selected from methoxy and ethoxy.

[0024] Optionally, the Y includes a branched structure;

[0025] The branched structure is selected from at least one of methane, ethane, propane, vinyl, propenyl, hydroxyl, and ester groups.

[0026] Preferably, Y is selected from one of C8-C12 long-chain aliphatic alkanes and C8-C12 long-chain aliphatic olefins.

[0027] Optionally, the modified PEG is a combination of high molecular weight modified PEG and low molecular weight modified PEG;

[0028] The molecular weight of the high molecular weight modified PEG is 1000-10000;

[0029] The low molecular weight modified PEG has a molecular weight of 200-1000.

[0030] Optionally, the molecular weight of the high molecular weight modified PEG is independently any value or a range between 1000, 1200, 1500, 1700, 1800, 2000, 2200, 2500, 2700, 2800, 3000, 4000, 5000, 6000, 7000, 8000, 9000, and 10000.

[0031] Optionally, the molecular weight of the low molecular weight modified PEG is independently any value or a range between any two of 200, 220, 250, 270, 300, 320, 350, 370, 400, 450, 500, 550, 600, 700, 800, 900, and 1000.

[0032] Optionally, the amount of high molecular weight modified PEG used is 1-20% by mass of low molecular weight modified PEG.

[0033] Optionally, the amount of the high molecular weight modified PEG, by mass, as a percentage of the low molecular weight modified PEG, is independently any value or a range between 1%, 2%, 3%, 5%, 6%, 7%, 9%, 10%, 11%, 12%, 15%, 17%, 18%, and 20%.

[0034] In this application, the modified PEG used is capped at one end with a functional group that coordinates with the quantum dots, and at the other end with a methoxy or ethoxy group. The introduction of methoxy or ethoxy groups can significantly reduce costs. Through the coordinated combination of modified PEGs with different molecular weights, high concentration, high PLQY, and stable dispersion of quantum dots in photoresist solvents such as PGMEA can be achieved.

[0035] Optionally, the quantum dot includes at least one of core-shell quantum dots and perovskite quantum dots.

[0036] Optionally, in the core-shell quantum dot, the core layer is selected from at least one of CdSe, CdTe, CdS, InP, InAs, ZnS, ZnTe, ZnSe, InGaP, InGaZnP, CdZnS, CdZnSe, and CdZnSeS;

[0037] The shell is selected from at least one of CdSe, CdTe, CdS, InP, InAs, ZnS, ZnTe, ZnSe, InGaP, InGaZnP, CdZnS, CdZnSe, and CdZnSeS;

[0038] The shell layer may be omitted.

[0039] Optionally, the perovskite quantum dot is ABX3;

[0040] Where A is Cs + MA + FA + 、Rb + K + At least one of them;

[0041] B is Pb 2+ Sn 2+ At least one of them;

[0042] X is Cl - ,Br - I - At least one of them.

[0043] Optionally, the quantum dot has an initial ligand selected from at least one of alkanes and alkenes having coordination or hydrogen bonding interactions.

[0044] Optionally, the initial ligand is selected from lipid-soluble ligands having a long C2-C18 fatty acid chain.

[0045] Preferably, the initial ligand is selected from lipid-soluble ligands having long C12-C18 fatty acid chains.

[0046] Optionally, the initial ligand is selected from at least one of mercaptoalkanes, mercaptoolefins, aminoalkanes, aminoolefins, phosphinoalkanes, phosphinoolefins, organosiloxanes, organosiloxanes, phosphoxyalkanes, phosphoxyolefins, sulfonic acid alkanes, sulfonic acid alkanes, carboxylalkanes, carboxylolefins, hydroxyalkanes, and hydroxyolefins.

[0047] Optionally, the initial ligand is selected from at least one of oleic acid and oleylamine.

[0048] Optionally, the photoresist solvent is selected from ester organic solvents and / or alcohol ether organic solvents.

[0049] Optionally, the photoresist solvent is selected from at least one of propylene glycol methyl ether acetate, propylene glycol methyl ether propionate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, ethylene glycol methyl ether acetate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol diethyl ether, diethylene glycol butyl ether, diethylene glycol butyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl 3-ethoxypropionate, n-propyl acetate, and isopropyl acetate.

[0050] Optionally, the second ligand is selected from at least one of mercaptohexanol, mercaptooctanol, mercaptoundecanol, mercaptohexanoic acid, mercaptooctanoic acid, mercaptoundecanoic acid, aminohexanol, aminooctanol, aminoundecanol, aminohexanoic acid, aminooctanoic acid, aminoundecanoic acid, glutaric acid, mercaptosuccinic acid, succinic acid, COOH-PEG-COOH, SH-PEG-COOH, and NH2-PEG-COOH.

[0051] Optionally, the addition ratio of the second ligand is 5%-30% of the molar amount of the modified PEG.

[0052] Optionally, the addition ratio of the second ligand is any value or a range between any two of the following values ​​for the molar amount of modified PEG: 5%, 6%, 7%, 8%, 10%, 12%, 13%, 15%, 17%, 20%, 22%, 25%, 27%, and 30%.

[0053] In this application, by adding a second ligand to introduce a carboxyl ligand that coordinates with the modified PEG, the acid value of the quantum dot dispersion can be adjusted (the acid value of the quantum dot dispersion can be determined by acid-base titration, pH test, Zeta potential, etc.), which can make it develop cleanly without residue in subsequent photolithography, effectively promoting the application of quantum dot dispersion in photolithographic patterning.

[0054] Optionally, the reaction temperature is 50-140°C;

[0055] The reaction time is 5-60 minutes.

[0056] Optionally, the reaction temperature is 80-120°C;

[0057] The reaction time is 20-40 minutes.

[0058] Optionally, the continued reaction time is 5-60 minutes.

[0059] Optionally, the continued reaction time is 20-40 minutes.

[0060] In this application, the temperature at which the reaction continues is the same as the temperature at which the previous reaction occurred.

[0061] According to a second aspect of this application, a quantum dot dispersion is provided.

[0062] The quantum dot dispersion prepared by the above-described preparation method has a quantum dot solid content of 300-1000 mg / ml.

[0063] Optionally, the solid content of the quantum dots is 400-600 mg / ml.

[0064] According to a third aspect of this application, an application of a quantum dot dispersion in photolithographic patterning is provided.

[0065] Application of quantum dot dispersions prepared by the above-described preparation method in photolithographic patterning.

[0066] Optionally, the application includes: mixing quantum dot dispersion and photoresist, followed by spin coating, pre-baking, exposure, post-baking, and development to obtain a quantum dot photoresist layer.

[0067] Optionally, after mixing the quantum dot dispersion and the photoresist, the mass of the quantum dot dispersion accounts for 10%-40% of the total mass.

[0068] Optionally, an alkaline aqueous solution is used in the developing process.

[0069] Optionally, the photoresist includes a solvent, a host resin, a monomer resin, a photoinitiator, a crosslinking agent, and light-diffusing particles.

[0070] In this application, quantum dot dispersion is mixed with photoresist and then subjected to a photolithography process to achieve patterning.

[0071] In this application, "C2-C18 long-chain aliphatic alkanes", "C2-C18 long-chain aliphatic alkenes", and "C2-C18 long aliphatic chains" refer to the number of C atoms in the long chain of aliphatic alkanes or alkenes.

[0072] Unless otherwise specified, all range values ​​in this application include endpoint values.

[0073] The beneficial effects that this application can produce include:

[0074] The method for preparing quantum dot dispersions and their application in photolithographic patterning provided in this application utilizes a synergistic combination of modified PEG and a second ligand. The modified PEG provides dispersibility, while the second ligand adjusts the acid value of the quantum dot dispersion, allowing it to be developed using an alkaline aqueous solution during patterning. The desired quantum dot dispersion can be obtained by directly mixing quantum dots, ligands, and solvents such as PGMEA at a specific temperature. Furthermore, the combination of high and low molecular weight modified PEGs can improve the PLQY of quantum dots in PGMEA, resulting in high concentration and stable dispersion of experimental quantum dots. The method is simple and can be directly applied to photolithographic patterning without subsequent cleaning. The photolithographic patterns obtained using the quantum dot dispersion prepared by this invention develop cleanly and with high resolution, effectively promoting the application of quantum dot dispersions in photolithographic patterning. Attached Figure Description

[0075] Figure 1 The diagram shows the preparation method of the quantum dot dispersion and the process flow of photolithographic patterning in the examples.

[0076] Figure 2 This is a schematic diagram of ligand exchange during the preparation of the quantum dot dispersion in the examples.

[0077] Figure 3 This is a photograph of the quantum dot dispersion prepared in Example 1.

[0078] Figure 4 This is a photograph of the quantum dot photoresist layer obtained after development in Example 1 under 365nm excitation.

[0079] Figure 5 The images shown are photographs of the quantum dot dispersion prepared in Example 9. The left image shows the dispersion after standing for 3 hours, and the right image shows the dispersion after heating at 40°C for 10 minutes.

[0080] Figure 6 This is a physical image of the quantum dot photoresist layer obtained after development in Comparative Example 1 under 365nm excitation.

[0081] Figure 7 This is a photograph of the quantum dot dispersion prepared in Comparative Example 2.

[0082] List of reference numerals in the attached diagram:

[0083] 1. Quantum dot; 2. Initial ligand for quantum dot; 3. Modified PEG; 4. Second ligand. Detailed Implementation

[0084] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0085] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0086] Unless otherwise specified, all test methods are standard and all instrument settings are those recommended by the manufacturer.

[0087] The analysis method in the embodiments of this application is as follows:

[0088] Photoluminescence quantum yield (PLQY) was measured and analyzed using an absolute fluorescence quantum efficiency analyzer (model C9920-92, during which the quantum dot dispersion was dispersed in the corresponding solvent and the absorbance was adjusted to 0.1).

[0089] The acid value of the quantum dot dispersion can be determined by neutralization titration, with phenolphthalein used as an indicator during titration.

[0090] The quantum dot photoresist layer obtained after development was analyzed by CSW-H4KTCL microscope under 365nm excitation. During the test, the sample was placed on the equipment and the appropriate focal length was adjusted for observation.

[0091] like Figure 1 The diagram shows the preparation method of quantum dot dispersion and the process flow diagram of photolithographic patterning. Quantum dots, ligands (modified PEG, second ligand), and photoresist solvent are directly mixed and reacted to obtain quantum dot dispersion. The quantum dot dispersion and photoresist are then mixed and photolithographically patterned.

[0092] like Figure 2 The diagram shown illustrates the ligand exchange process during the preparation of a quantum dot dispersion. Quantum dots involve a ligand exchange process, where 1 represents the quantum dot, 2 represents the initial ligand of the quantum dot, 3 represents the modified PEG, and 4 represents the second ligand.

[0093] Example 1

[0094] In this embodiment, the quantum dot core layer is CdSe, the shell layer is ZnS, and the ligand is oleic acid. 1g of quantum dots, 0.1g of CH3O-PEG-COOH 2000 (CH3O- is the end-capping group of PEG, -COOH is the group that interacts with the quantum dot surface, molecular weight 2000), 1g of CH3O-PEG-COOH 350, and 2ml of PGMEA were mixed and reacted at 100℃ for 20min. Then, 80mg of mercaptoundecanoic acid (12.6% of the total molar amount of modified PEG) was added, and the reaction continued for another 30min to obtain a clear and transparent quantum dot dispersion. Figure 3 As shown in the figure. The solid content of the quantum dots is 500 mg / ml.

[0095] Quantum dot photoresist was prepared by mixing quantum dot dispersion with photoresist, with the quantum dot dispersion accounting for 20% of the total mass. The prepared quantum dot photoresist was spin-coated on a glass substrate at 1000 rpm for 60 s, pre-baked at 90°C for 3 min, and then analyzed under a photomask at 365 nm and 100 mJ / cm². 2 The photoresist layer was obtained by exposing the photoresist layer to an energy level of 3 seconds and then developing it with a 0.045% potassium hydroxide aqueous solution for 60 seconds. Figure 4 The image shows the quantum dot photoresist layer obtained after development under 365nm excitation. It can be seen that the image is clean and clear with no residue.

[0096] Example 2

[0097] In this embodiment, the quantum dot core layer is CdSe, the shell layer is ZnS, and the ligand is oleic acid. 1g of quantum dots, 0.05g of CH3O-PEG-NH2 2000, 0.5g of CH3O-PEG-NH2 350, and 2ml of PGMEA were mixed and reacted at 100℃ for 20min. Then, 40mg of mercaptoundecanoic acid (12.6% of the total molar amount of modified PEG) was added, and the reaction was continued for another 30min to obtain a clear and transparent quantum dot dispersion. The remaining steps were the same as in Example 1. The solid content of the quantum dots was 500mg / ml.

[0098] Example 3

[0099] In this embodiment, the quantum dot core layer is CdSe, the shell layer is ZnS, and the ligand is oleic acid. 1g of quantum dots, 0.05g of CH3O-PEG-SH 2000, 0.5g of CH3O-PEG-SH 350, and 2ml of PGMEA were mixed and reacted at 100℃ for 20min. Then, 40mg of mercaptoundecanoic acid (12.6% of the total molar amount of modified PEG) was added, and the reaction was continued for another 30min to obtain a clear and transparent quantum dot dispersion. The remaining steps were the same as in Example 1. The solid content of the quantum dots was 500mg / ml.

[0100] Example 4

[0101] In this embodiment, the quantum dot core layer is CdSe, the shell layer is ZnS, and the ligand is oleic acid. 1g of quantum dots, 0.05g of CH3CH2O-PEG-SH 2000, 0.5g of CH3CH2O-PEG-SH 350, and 2ml of PGMEA were mixed and reacted at 100℃ for 20min. Then, 40mg of mercaptoundecanoic acid (12.6% of the total molar amount of modified PEG) was added, and the reaction was continued for another 30min to obtain a clear and transparent quantum dot dispersion. The remaining steps were the same as in Example 1. The solid content of the quantum dots was 500mg / ml.

[0102] Example 5

[0103] In this embodiment, the quantum dot core layer is CdSe, the shell layer is ZnS, and the ligand is oleic acid. 1g of quantum dots, 0.05g of CH3O-PEG-SH 2000, 0.5g of CH3O-PEG-SH 350, and 2ml of PGMEA were mixed and reacted at 100℃ for 20min. Then, 40mg of 3-methyl-11-mercaptoundecanoic acid (12.6% of the total molar amount of modified PEG) was added, and the reaction was continued for another 30min to obtain a clear and transparent quantum dot dispersion. The remaining steps were the same as in Example 1. The solid content of the quantum dots was 500mg / ml.

[0104] Example 6

[0105] In this embodiment, the quantum dot core layer is CdSe, the shell layer is ZnS, and the ligand is oleic acid. 1g of quantum dots, 0.1g of CH3O-PEG-COOH 2000, 1g of CH3O-PEG-COOH 350, and 2ml of PGMEA were mixed and reacted at 100℃ for 20min. Then, 0.1g of COOH-PEG-COOH 600 (5.7% of the total molar amount of modified PEG) was added, and the reaction was continued for another 30min to obtain a clear and transparent quantum dot dispersion. The remaining steps were the same as in Example 1. The solid content of the quantum dots was 500mg / ml.

[0106] Example 7

[0107] In this embodiment, the quantum dot core layer is CdSe, the shell layer is ZnS, and the ligand is oleic acid. 1g of quantum dots, 0.1g of CH3O-PEG-C8 2000, 1g of CH3O-PEG-C8 350, and 2ml of PGMEA were mixed and reacted at 100℃ for 20min. Then, 0.1g of COOH-PEG-COOH 600 (5.7% of the total molar amount of modified PEG) was added, and the reaction was continued for another 30min to obtain a clear and transparent quantum dot dispersion. The remaining steps were the same as in Example 1. The solid content of the quantum dots was 500mg / ml.

[0108] Example 8

[0109] In this embodiment, the quantum dot core layer is CsPbBr3, and the ligands are oleic acid and oleylamine. 1g of quantum dots, 0.05g of CH3O-PEG-COOH 2000, 0.5g of CH3O-PEG-COOH 350, and 2ml of PGMEA were mixed and reacted at 100℃ for 20min. Then, 0.05g of COOH-PEG-COOH 600 (5.7% of the total molar amount of modified PEG) was added, and the reaction was continued for another 30min to obtain a clear and transparent quantum dot dispersion. The remaining steps were the same as in Example 1. The solid content of the quantum dots was 500mg / ml.

[0110] Example 9

[0111] In this embodiment, the quantum dot core layer is CdSe, the shell layer is ZnS, and the ligand is oleic acid. 1g of quantum dots, 1g of CH3O-PEG-COOH 5000, and 2ml of PGMEA were mixed and reacted at 100℃ for 20min. Then, 5.5mg of mercaptoundecanoic acid (12.6% of the total molar amount of modified PEG) was added, and the reaction was continued for another 30min to obtain a clear and transparent quantum dot dispersion. After the quantum dots were allowed to stand for 3h, the solution transparency decreased, and some precipitate formed, such as... Figure 5 As shown in the left figure, the quantum dot dispersion obtained in this example can be restored to a clear and transparent state by heating at 40°C for 10 minutes, as shown in the left figure. Figure 5 As shown in the figure on the right.

[0112] Example 10

[0113] In this embodiment, the quantum dot core layer is CdSe, the shell layer is ZnS, and the ligand is oleic acid. 1g of quantum dots, 1g of CH3O-PEG-COOH 350, and 5ml of PGMEA were mixed and reacted at 100℃ for 20min. Then, 80mg of mercaptoundecanoic acid (12.6% of the total molar amount of modified PEG) was added, and the reaction was continued for another 30min to obtain a clear and transparent quantum dot dispersion.

[0114] The quantum dot dispersions from the above examples were allowed to stand at 25°C for 10 days. The standing condition was observed, and the PLQY (partial quantitation efficiency) was measured. The experimental results are shown in Table 1. It can be seen that, except for Example 9, the solutions after the reaction were all clear and transparent, and all were suitable for practical use. The quantum dot dispersion obtained in Example 9, however, could be restored to a clear and transparent state after heating at 40°C for 10 minutes, and was also suitable for practical use.

[0115] It can be seen that high molecular weight modified PEG is beneficial for obtaining quantum dot dispersions with high PLQY, but the dispersions cannot remain stable for a long time; low molecular weight modified PEG has the opposite effect. As a preferred embodiment, the combined use of the two can solve the above problems and obtain quantum dot dispersions with high solid content, high PLQY, and long-term stable dispersion.

[0116] Table 1

[0117]

[0118] Comparative Example 1

[0119] In this embodiment, the quantum dot core layer is CdSe, the shell layer is ZnS, and the ligand is oleic acid. 1g of quantum dots, 0.1g of CH3O-PEG-COOH 2000, 1g of CH3O-PEG-COOH 350, and 2ml of PGMEA were mixed and reacted at 100℃ for 30min to obtain a clear and transparent quantum dot dispersion.

[0120] The acid value of the quantum dot dispersions obtained in Example 1 and this comparative example was determined. For each determination, 20 μL of the quantum dot dispersion was dissolved in 10 mL of ethanol, 1-2 drops of phenolphthalein indicator were added, and titration was performed with a 0.02 mol / L KOH ethanol solution until the solution turned red and did not change color for 30 seconds. The experimental results are shown in Table 2, indicating that the second ligand is beneficial to improving the acid value of the quantum dot solution.

[0121] Table 2

[0122]

[0123] The quantum dot dispersion obtained in Comparative Example 1 was mixed with photoresist to obtain a quantum dot photoresist. The quantum dot dispersion was controlled to account for 20% of the total mass. The prepared quantum dot photoresist was spin-coated on a glass substrate at 1000 rpm for 5 s, pre-baked at 90°C for 3 min, exposed at 365 nm and 100 mJ energy for 3 s under a custom mask, and finally developed with a 0.045% potassium hydroxide aqueous solution for 60 s to obtain the quantum dot photoresist layer. The result after photolithography and development is as follows. Figure 6 As shown, the image contains many residual patterns that were not completely cleaned. This indicates that the second ligand is beneficial for alkaline development.

[0124] Comparative Example 2

[0125] In this comparative example, the quantum dot core was CdSe, the shell was ZnS, and the ligand was oleic acid. Mixing 1g of quantum dots, 0.5g of COOH-PEG-COOH 600, and 2ml of PGMEA and reacting at 100℃ for 20min did not yield a clear, transparent solution. The experimental results are as follows... Figure 7 As shown, a clear and transparent solution was not obtained after the reaction, and it remained in this state even after heating at 40°C for 10 minutes. This indicates that the existing COOH-PEG-COOH 600 technology cannot produce a clear and transparent solution. The reason may be that the carboxyl groups at both ends of the modified PEG interact with the quantum dots simultaneously, preventing them from dispersing well in the solvent. This example also illustrates the necessity of using methoxy, ethoxy, and other end-capping groups to modify PEG in this application, and also demonstrates that the small amount of COOH-PEG-COOH 600 added can only be used as a second ligand, and not as a dispersing ligand.

[0126] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for producing a quantum dot dispersion liquid, characterized by, Mixing, reacting, adding second ligand and continuing to react quantum dots, modified PEG and photoresist solvent to obtain the quantum dot dispersion; The modified PEG is B-PEG-A, and the structural formula is as follows: The structural formula of the second ligand is as follows: Wherein, A is independently a group having interaction with the surface of quantum dots, including one of coordination interaction, hydrogen bond interaction and van der Waals force interaction; B is a capping group of PEG, which has no interaction with quantum dots; X is a group interacting with basic group, selected from one of carboxyl, phenolic hydroxyl, sulfonic acid group and mercapto group; Y is a skeleton structure connecting A and X, including one of C2-C18 long chain aliphatic alkane, C2-C18 long chain aliphatic alkene and PEG structure; The molecular weight of the modified PEG is 200-10000.

2. The production method according to claim 1, characterized by, The mass ratio of the quantum dots and the modified PEG is 1:0.1-2; Preferably, the mass ratio of the quantum dots and the photoresist solvent is 1:2-20.

3. The preparation method according to claim 1, characterized in that, When the A is the coordination interaction, the A is selected from one of mercapto group, carboxyl group, amino group, organic phosphine group, organic phosphine oxide group and sulfonic acid group; When the A is the hydrogen bond interaction, the A is selected from hydroxyl group; When the A is the van der Waals force interaction, the A is selected from one of C2-C18 long chain aliphatic alkane and C2-C18 long chain aliphatic alkene; Preferably, the A is selected from one of C8-C12 long chain aliphatic alkane and C8-C12 long chain aliphatic alkene; Preferably, the B is selected from one of methoxy group and ethoxy group; Preferably, the Y includes a branched structure; The branched structure is selected from at least one of methane group, ethane group, propane group, ethylene group, propylene group, hydroxyl group and ester group; Preferably, the Y is selected from one of C8-C12 long chain aliphatic alkane and C8-C12 long chain aliphatic alkene.

4. The production method according to claim 1, characterized by, The modified PEG is a combination of high molecular weight modified PEG and low molecular weight modified PEG; The molecular weight of the high molecular weight modified PEG is 1000-10000; The molecular weight of the low molecular weight modified PEG is 200-1000; Preferably, the amount of the high molecular weight modified PEG accounts for 1-20% of the low molecular weight modified PEG by mass.

5. The preparation method according to claim 1, characterized in that, The quantum dots include at least one of core-shell structure quantum dots and perovskite quantum dots; Preferably, in the core-shell structure quantum dots, the core layer is selected from at least one of CdSe, CdTe, CdS, InP, InAs, ZnS, ZnTe, ZnSe, InGaP, InGaZnP, CdZnS, CdZnSe and CdZnSeS; The shell layer is selected from at least one of CdSe, CdTe, CdS, InP, InAs, ZnS, ZnTe, ZnSe, InGaP, InGaZnP, CdZnS, CdZnSe and CdZnSeS; The shell layer can not be used; Preferably, the perovskite quantum dots are ABX3; wherein A is Cs + , MA + , FA + , Rb + , K + at least one of B is at least one of Pb 2+ , Sn 2+ . X is at least one of Cl - , Br - , I - .

6. The method of claim 1, wherein, The quantum dots have initial ligands, and the initial ligands are selected from at least one of alkanes having coordination or hydrogen bond interaction and alkenes having coordination or hydrogen bond interaction. Preferably, the initial ligand is selected from at least one of liposoluble ligands with C2-C18 long aliphatic chain. Preferably, the initial ligand is selected from at least one of mercaptoalkane, mercaptoalkene, aminoalkane, aminoalkene, phosphinoalkane, phosphinoalkene, organosiloxanealkane, organosiloxanealkene, phosphineoxyalkane, phosphineoxyalkene, sulfonic acid alkane, sulfonic acid alkene, carboxyalkane, carboxyalkene, hydroxyalkane, hydroxyalkene. Preferably, the photoresist solvent is selected from at least one of ester organic solvent and / or alcohol ether organic solvent. Preferably, the photoresist solvent is selected from at least one of propylene glycol methyl ether acetate, propylene glycol methyl ether propionate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, ethylene glycol methyl ether acetate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, diethylene glycol diethyl ether, diethylene glycol butyl ether, diethylene glycol butyl ether acetate, diethylene glycol monoethyl ether acetate, 3-ethoxypropyl acetate, n-propyl acetate, isopropyl acetate.

7. The preparation method according to claim 1, characterized in that, The second ligand is selected from at least one of mercaptohexanol, mercaptooctanol, mercaptoundecanol, mercaptohexanoic acid, mercaptooctanoic acid, mercaptoundecanoic acid, amino hexanol, amino octanol, amino undecanol, amino hexanoic acid, amino octanoic acid, amino undecanoic acid, glutaric acid, mercaptosuccinic acid, suberic acid, COOH-PEG-COOH, SH-PEG-COOH, NH2-PEG-COOH. Preferably, the addition ratio of the second ligand is 5%-30% of the molar amount of modified PEG.

8. The method of claim 1, wherein, The temperature of the reaction is 50-140℃; The time of the reaction is 5-60min; Preferably, the time of the continued reaction is 5-60min.

9. The quantum dot dispersion liquid prepared by the production method according to any one of claims 1 to 8, characterized by, The solid content of quantum dots in the quantum dot dispersion liquid is 300-1000mg / ml.

10. The application of the quantum dot dispersion liquid prepared by the preparation method of any one of claims 1-8 in photoetching patterning. Preferably, the application comprises: After mixing the quantum dot dispersion liquid and the photoresist, spin coating, pre-baking, exposure, post-baking, development are performed to obtain a quantum dot photoresist layer. Preferably, after mixing the quantum dot dispersion liquid and the photoresist, the mass of the quantum dot dispersion liquid accounts for 10%-40% of the total mass. Preferably, in the development, an alkaline aqueous solution is used.

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