Quantum dot ink preparation method and display device preparation method

Abstract

The present application relates to a method for preparing quantum dot ink, including a first surface modification, by preparing a first modification solution containing a polysulfide compound surfactant, adding a quantum dot initial solution and tetraethyl orthosilicate, then separating and dispersing in a second dispersion solvent, performing a second surface modification, adjusting the pH value of the quantum dot secondary solution, adding a second modification solution containing a long-chain alkyl silane and chloroform, separating and dispersing in a third dispersion solvent again, and finally mixing the quantum dot tertiary solution with a fourth dispersion solvent containing an organic silicone resin to form a quantum dot ink. The present application also provides a method for preparing a display device using the quantum dot ink, including printing quantum dot inks of different colors using inkjet printing technology. Through multi-step surface modification and optimized process parameters, long-term stable dispersion of quantum dots in solvents is achieved, the stability and application performance of quantum dot inks are improved, the process flow is simplified, and production efficiency is improved.

Description

Technical Field

[0001] The present application relates to the technical field of quantum dot materials, and in particular to a method for preparing quantum dot ink and a method for preparing a display device. Background Art

[0002] In recent years, quantum dots have shown their potential for application in display technology and lighting, especially in micro-display technology. As a color conversion layer, quantum dots provide an innovative solution for achieving full-color display by combining with blue Micro-LED backlight. This technical path enriches the saturation and purity of displayed colors, and also promotes the further miniaturization and efficiency of display technology. As a technology in the field of solution processing, inkjet printing technology can become one of the processes in quantum dot applications because of its advantages of not requiring high-precision masks, high material utilization, flexible patterning, and easy compatibility with large-size display devices. Inkjet printing technology can construct a uniform and fine quantum dot light-emitting layer on the substrate.

[0003] However, although quantum dot inkjet printing technology has made some progress in the display field, it still faces a series of challenges. The primary problem lies in the stability of quantum dot ink during long-term printing. Due to the interaction between quantum dot particles and the volatilization of solvents, the ink is often prone to precipitation, which not only affects the uniformity and stability of the ink, but also easily leads to nozzle clogging, thereby causing differences in printing quality, which will limit the widespread application of quantum dot inkjet printing technology.

[0004] In addition, as the size of display devices continues to increase, the time required for inkjet printing has also increased significantly, which undoubtedly reduces production efficiency and increases production costs. This problem is particularly prominent in large-scale production, and has become one of the bottlenecks restricting the rapid development of quantum dot display technology. Therefore, it is necessary to develop a new method for preparing quantum dot ink, aiming to simplify the process flow, merge the steps in the traditional process, and at the same time improve the stability and printing efficiency of quantum dot ink, solve the key problems of quantum dot ink precipitation and long printing time in the existing technology, and provide support for the further application of quantum dot display technology. Summary of the invention

[0005] The purpose of this application is to provide a method for preparing quantum dot ink, which not only increases the uniformity of quantum dot ink during long-term printing, but also simplifies the process flow and improves production efficiency. The purpose of this application is achieved through the following technical solutions, and the method specifically includes: Performing a first surface modification specifically includes: preparing a first modification solution including a first modification solvent and a surfactant, wherein the surfactant includes a polysulfide compound, adding a quantum dot initial solution to the first modification solution, and then adding tetraethyl orthosilicate to form a first mixed solution, wherein the quantum dot initial solution includes quantum dots and a first dispersing solvent; Separating the quantum dots that have undergone the first surface modification from the first mixed solution and dispersing them in a second dispersing solvent to form a quantum dot secondary solution; Performing a second surface modification, specifically comprising: adjusting the pH value of the quantum dot secondary solution to within the range of 8-11, adding a second modification solution after the pH value is adjusted to form a second mixed solution, wherein the second modification solution comprises long-chain alkyl silane and chloroform; Separating the quantum dots that have undergone the second surface modification from the second mixed solution and dispersing them in a third dispersing solvent to form a quantum dot tertiary solution; The quantum dot tertiary solution is mixed with a fourth dispersing solvent to form a quantum dot ink, wherein the fourth dispersing mixed solvent includes an organic silicone resin.

[0006] In one embodiment, the quantum dots in the initial quantum dot solution have a size greater than 15 nm.

[0007] In one embodiment, after forming the first mixed solution, the first mixed solution is further sealed and stirred, and after forming the second mixed solution, the first mixed solution is further stirred, and the stirring time is greater than 12 hours.

[0008] In one embodiment, the quantum dots are separated from the solution by centrifugation, and the quantum dots are washed.

[0009] In one of the embodiments, the volume ratio of the quantum dot tertiary solution to the fourth dispersing solvent is in the range of 1:3-1:5.

[0010] In one embodiment, adjusting the pH value of the quantum dot secondary solution specifically includes adding ammonia water to the quantum dot secondary solution.

[0011] In one of the embodiments, the viscosity of the quantum dot ink is adjusted by adjusting the amount of chloroform added.

[0012] In addition, the present application also provides a method for preparing a display device, comprising: Using the aforementioned quantum dot ink preparation method to obtain quantum dot inks of different colors; Printing the quantum dot ink at positions corresponding to different colors by inkjet printing; The quantum dot ink is baked.

[0013] In one embodiment, quantum dot inks of different colors include red quantum dot ink and green quantum dot ink, and also include printing blank ink at positions corresponding to blank colors.

[0014] In one of the embodiments, it also includes forming a substrate, forming a trapezoidal hole on the substrate, printing quantum dot inks of different colors in the trapezoidal hole by inkjet printing, and after baking, aligning and bonding the substrate to the LED blue light array.

[0015] Compared with the prior art, this application has the following beneficial effects: This application improves the dispersion stability of quantum dots in ink through two surface modification processes. First, a first modification solution using a polysulfide compound as a surfactant is mixed with an initial solution of quantum dots and tetraethyl orthosilicate to form a first mixed solution to reduce the agglomeration between quantum dots. Subsequently, by adjusting the pH value and adding a second modification solution of long-chain alkyl silane and chloroform, the quantum dots can be further maintained in a uniformly dispersed state during long-term printing, which can effectively solve the problems of easy precipitation and easy clogging of the nozzle in the prior art of quantum dot ink, and ensure the stability and consistency of the printing quality.

[0016] Since the quantum dot ink in this application not only has excellent printing performance, its unique composition design also enables the ink to form a protective layer through thermal curing during the baking process, so there is no need to cover an additional protective layer after printing the quantum dot light-emitting layer. It not only simplifies the process and reduces the production steps, but also improves production efficiency. In addition, by adjusting the amount of chloroform added, the viscosity of the quantum dot ink can be flexibly adjusted to further meet the needs of different printing equipment and process parameters. This application successfully simplifies the process flow, reduces production costs, and improves production efficiency through the technical innovation of forming a protective layer through thermal curing. At the same time, the viscosity adjustability of the ink enhances its adaptability under different printing conditions and provides support for large-scale industrial production.

[0017] In the display device preparation method, the present application utilizes the quantum dot ink preparation method to obtain quantum dot inks of different colors, and accurately prints them at corresponding positions through inkjet printing, thereby realizing full-color, high-efficiency, and low-cost display device preparation, which can simplify the process flow, improve production efficiency, and thus enhance the performance and stability of the display device. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic flow chart of a method for preparing quantum dot ink in one embodiment of the present application; Figure 2 It is a schematic diagram of the structure of a display device in one embodiment of the present application.

[0019] Explanation of the reference numerals: 110, red quantum dot ink; 120, green quantum dot ink; 130, blank quantum dot ink; 200, substrate; 210, reflective layer; 300, LED blue light array. DETAILED DESCRIPTION

[0020] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. It is to be understood that the specific embodiments described herein are only used to explain the present application, rather than to limit the present application. It should also be noted that, for ease of description, only some structures related to the present application are shown in the accompanying drawings, rather than all structures. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0021] The terms "including" and "having" and any variations thereof in this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device comprising a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0022] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0023] As one of the materials for new display technology, quantum dot ink is gradually showing its great potential in the field of high-definition, high-color saturation and low-energy display. The preparation process of quantum dot ink is not only related to the stable dispersion of quantum dots, but also directly affects the performance and stability of the final display device. The following is a detailed introduction to the preparation method of quantum dot ink of this application. Through fine surface modification and optimized process parameters, the long-term stable dispersion of quantum dots in the solvent is achieved. Please refer to Figure 1 , Figure 1It is a flow diagram of a method for preparing quantum dot ink in an embodiment of the present application, and the method for preparing quantum dot ink includes: performing a first surface modification, which specifically includes: preparing a first modification solution including a first modification solvent and a surfactant, wherein the surfactant includes a polysulfide compound, adding a quantum dot initial solution to the first modification solution, and then adding tetraethyl orthosilicate to form a first mixed solution, wherein the quantum dot initial solution includes quantum dots and a first dispersing solvent; separating the quantum dots that have undergone the first surface modification from the first mixed solution, and dispersing them in a second dispersing solvent to form a quantum dot secondary solution; performing a second surface modification, which specifically includes: adjusting the pH value of the quantum dot secondary solution to a range of 8-11, and adding a second modification solution after the pH value is adjusted to form a second mixed solution, wherein the second modification solution includes long-chain alkyl silane and chloroform; separating the quantum dots that have undergone the second surface modification from the second mixed solution, and dispersing them in a third dispersing solvent to form a quantum dot tertiary solution; mixing the quantum dot tertiary solution with a fourth dispersing solvent to form quantum dot ink, wherein the fourth dispersing mixed solvent includes an organic silicone resin.

[0024] First, a first modification solution including a first modification solvent (such as cyclohexane) and a surfactant (such as polyoxyethylene (5) nonylphenyl ether sulfide, and other polysulfide compounds can also be used) is prepared. Subsequently, the initial solution of quantum dots (quantum dots dispersed in the first dispersion solvent such as toluene) is added to the solution, and then tetraethyl orthosilicate is added. After stirring and reacting, a first mixed solution is formed. This step of surface modification is intended to preliminarily improve the dispersibility of quantum dots in the solvent and reduce agglomeration. As a surfactant, the polysulfide compound can be adsorbed on the surface of the quantum dots to form a protective layer, which effectively prevents the agglomeration of the quantum dots due to surface defects. The addition of tetraethyl orthosilicate helps to further stabilize the quantum dots and provide a basis for their subsequent secondary modification.

[0025] The quantum dots that have undergone the first surface modification are separated from the first mixed solution, usually by centrifugation and washing. Then, the separated quantum dots are dispersed in a second dispersion solvent (such as ethanol) to form a quantum dot secondary solution. This step of separation and secondary dispersion helps to remove unbound surfactants and impurities and improve the purity of quantum dots. At the same time, by changing the dispersion solvent, the dispersibility of quantum dots in the solvent can be further optimized.

[0026] In the second surface modification, the pH value of the quantum dot secondary solution is first adjusted to the range of 8-11, usually by adding an alkaline solution (such as ammonia water). After the pH value is adjusted, the second modification solution (including long-chain alkyl silanes such as trimethoxyoctadecylsilane and chloroform) is added to form a second mixed solution. Through stirring and reaction, the long-chain alkyl silane interacts with functional groups such as hydroxyl groups on the surface of the quantum dots to form a more stable chemical bond. The introduction of long-chain alkyl silanes not only provides longer hydrophobic segments for quantum dots, but also reduces the interaction between quantum dots and solvent molecules, thereby improving the dispersion stability of quantum dots; at the same time, long-chain alkyl silanes can also form better compatibility and bonding with the resin substrate added later, providing a basis for the preparation of quantum dot inks. The long-chain alkyl silanes specifically selected are trimethoxyoctadecylsilane, hexadecyltrimethoxysilane, and dodecyltrimethoxysilane.

[0027] The quantum dots that have undergone the second surface modification are separated from the second mixed solution, also through steps such as centrifugation and washing. Then, the separated quantum dots are dispersed in a third dispersion solvent (such as chloroform) to form a quantum dot tertiary solution. This step of separation and tertiary dispersion helps to remove unreacted long-chain alkyl silanes and impurities, further improving the purity of the quantum dots. At the same time, by changing the dispersion solvent, the compatibility of the quantum dots in the subsequent mixing with the resin can be further optimized.

[0028] The quantum dot tertiary solution is mixed with the fourth dispersing solvent (including silicone resin, such as Dow Corning OE 6550), and quantum dot ink is formed by stirring and homogenizing. The introduction of silicone resin not only provides a good dispersion medium and protective layer for quantum dots, but also gives quantum dot ink excellent printing performance and film-forming properties. In addition, by adjusting the type and proportion of silicone resin, the performance parameters of quantum dot ink such as viscosity, fluidity and curing speed can be further optimized to meet the preparation requirements of different display devices. The quantum dot ink preparation method of the present application achieves long-term stable dispersion of quantum dots in solvents and excellent application performance through multi-step surface modification and process control.

[0029] Specifically, the quantum dot size in the initial quantum dot solution is greater than 15nm. Larger quantum dots generally have lower surface energy, which means that they are less likely to agglomerate or precipitate, thereby improving the dispersion stability and long-term storage stability of quantum dots in solvents. In the preparation process of quantum dot inks, the compatibility between quantum dots and solvents, surfactants, and subsequently added resin substrates is an important consideration. Larger quantum dots generally have lower specific surface area and fewer surface defects, which makes it easier for them to form stable interactions with solvents and other additives. Quantum dot core materials include specific materials such as cadmium selenide, cadmium sulfide or perovskite materials. Quantum dots can also be core-shell structures, and quantum dot shell materials include materials such as zinc sulfide and cadmium sulfide.

[0030] Specifically, after forming the first mixed solution, the first mixed solution is also sealed and stirred, and after forming the second mixed solution, the first mixed solution is also stirred, and the stirring time is greater than 12 hours. Sealing and stirring the first mixed solution can ensure that all components are fully mixed in a closed environment, avoiding interference from external impurities, and long-term stirring helps to further break the weak agglomeration between quantum dots, so that they can reach a higher dispersion state, which is crucial for the subsequent preparation of high-quality quantum dot ink. When forming the first mixed solution, sealed stirring helps to accelerate the chemical reaction between quantum dots and surfactants and tetraethyl orthosilicate to form stable chemical bonds. Chemical bonding can not only enhance the stability of quantum dots, but also provide a good foundation for their subsequent secondary modification. Long-term stirring of the first mixed solution (or related intermediates) also helps the components that have not completely reacted to continue to react, thereby improving the overall reaction efficiency.

[0031] Specifically, the quantum dots are separated from the solution by centrifugation, and the quantum dots are washed. In order to ensure efficient and pure separation of quantum dots, centrifugation is used as the main means. Centrifugation uses the centrifugal force generated by rotation to separate substances of different masses and densities, thereby achieving effective separation of quantum dots from other components of the solution. Through centrifugation and subsequent washing treatment, impurities attached to the surface of quantum dots can be removed and the purity of quantum dots can be improved. High-purity quantum dots are crucial to improving the performance of subsequent quantum dot inks or display devices, and can reduce the negative impact of impurities on the luminous efficiency and stability of quantum dots. Washing treatment can also remove excess surfactants or other unstable factors that may exist on the surface of quantum dots, which helps to enhance the chemical stability and long-term storage stability of quantum dots.

[0032] Specifically, the volume ratio of the quantum dot tertiary solution to the fourth dispersing solvent is in the range of 1:3-1:5. The volume ratio of the quantum dot tertiary solution to the fourth dispersing solvent is controlled within the above range to ensure uniform dispersion of the quantum dots in the ink. Too high a concentration of quantum dots may lead to agglomeration, while too low a concentration may reduce the luminescence performance of the ink. By regulating this ratio, the best dispersion effect can be obtained, so that the quantum dots can be stably present in the ink as single particles. The appropriate volume ratio helps to reduce the interaction between quantum dots, thereby reducing the risk of agglomeration and precipitation. In addition, the selection and proportion control of the fourth dispersing solvent can also affect the charge distribution on the surface of the quantum dots. By adjusting the volume ratio of the quantum dot tertiary solution to the fourth dispersing solvent, key indicators such as the viscosity, fluidity, and luminescence performance of the ink can also be flexibly adjusted.

[0033] Specifically, adjusting the pH value of the quantum dot secondary solution specifically includes adding ammonia water to the quantum dot secondary solution. The stability of quantum dots is closely related to the charge state of their surface. By adding ammonia water to adjust the pH value of the solution, the charge distribution on the surface of the quantum dots can be affected, thereby enhancing its stability. Under appropriate pH conditions, the charge layer on the surface of the quantum dots is more stable, can more effectively resist agglomeration and precipitation, and maintain long-term dispersion stability. In the subsequent steps of quantum dot preparation, such as surface modification and dispersion of quantum dots, they all need to be carried out under specific pH conditions. By adjusting the pH value of the quantum dot secondary solution in advance, a good starting point is provided for subsequent processing. The method of adjusting the pH value using ammonia water has the advantages of simple operation and rapid reaction. By accurately controlling the amount and speed of ammonia water added, the pH value of the quantum dot secondary solution can be quickly adjusted to the target range, thereby improving production efficiency.

[0034] Specifically, it also includes adjusting the viscosity of the quantum dot ink by adjusting the amount of chloroform added. In the process of preparing quantum dot ink, it also includes effectively adjusting the viscosity of the quantum dot ink by accurately controlling the amount of chloroform added. The viscosity of the quantum dot ink directly affects its subsequent coating, printing and film-forming properties. Too low viscosity may cause the ink to flow easily during application and it is not easy to form a uniform coating; while too high viscosity may increase the difficulty of processing and even affect the photoelectric performance of the final product. By carefully adjusting the amount of chloroform added, precise control of the viscosity of the quantum dot ink can be achieved. Chloroform, as an organic solvent, acts as a diluent in the quantum dot ink, which can change the interaction force between the quantum dots and the solvent molecules in the ink, thereby affecting the overall viscosity. The addition of an appropriate amount of chloroform can make the ink reach a suitable viscosity range, which not only ensures good fluidity, but also ensures the uniformity and stability of the coating.

[0035] In addition, the present application also provides a method for preparing a display device, comprising: using the aforementioned quantum dot ink preparation method to obtain quantum dot inks of different colors; printing the quantum dot inks at positions corresponding to different colors using an inkjet printing method; and baking the quantum dot inks.

[0036] First, using the aforementioned quantum dot ink preparation method, quantum dot inks of various colors (such as red, green, etc.) are obtained. The quantum dot inks are not only pure in color, but also have high luminous efficiency. Advanced inkjet printing technology is used to accurately print these quantum dot inks of different colors to the corresponding positions of different colors of the display device. Inkjet printing technology is known for its high precision, high resolution and flexible color management capabilities. It can ensure the precise positioning and uniform distribution of quantum dot inks on the display device, thereby greatly improving efficiency. Finally, the printed quantum dot ink is baked. This step is intended to remove the solvent in the ink. During the baking process, the temperature and time need to be strictly controlled to avoid damage to the quantum dots due to overheating, while ensuring that the solvent can fully evaporate to form a dense quantum dot film. Compared with the traditional display device preparation process, this application uses a highly automated inkjet printing technology to improve production efficiency and reduce production costs.

[0037] Specifically, quantum dot inks of different colors include red quantum dot ink 110 and green quantum dot ink 120. During the inkjet printing process, blank ink 130 is also printed at the corresponding position of the blank color. The red quantum dots and green quantum dots are prepared by specific quantum dot synthesis processes, respectively. These quantum dots have excellent optical properties and can emit pure red and green light at specific wavelengths. By precisely controlling the size and composition of the quantum dots, the luminous efficiency and color purity of these inks can be further optimized, thereby meeting the high requirements of the display device for color. The quantum dot ink preparation method of the present application is used to form the quantum dots into stable quantum dot ink. The blank ink 130 does not convert light, and its specific preparation method is not limited, as long as the wavelength of the light emitted by the LED blue light array 300 is not converted. The specific method can be selected from the following methods: using silicon dioxide or titanium dioxide nanoparticles with a particle size of about 50-200nm, taking silicon dioxide or titanium dioxide nanoparticles and uniformly mixing them with silicone resin to form blank ink 130, the specific silicone resin is Dow Corning OE 6550, wherein A: B = 1:4, the mass fraction of silicon dioxide or titanium dioxide nanoparticles in the blank ink 130 is 20%, and the viscosity coefficient can be further adjusted by adding a trace amount of chloroform, so that the blank ink 130 can also be printed at the position corresponding to the blank color by inkjet printing, which can keep the original color of the LED blue light array 300, and the red quantum dot ink 110 and the green quantum dot ink 120 can convert the blue light emitted by the blue light array 300 into red light and green light respectively, so that red, green and blue are used as the three primary colors, and full-color display is achieved by adjusting the proportion of the three primary colors, so that the color of the display device is rich.

[0038] See also Figure 2 , Figure 2 is a schematic diagram of the structure of a display device in an embodiment of the present application, specifically, it also includes forming a substrate 200, forming a trapezoidal hole on the substrate 200, printing quantum dot inks of different colors in the trapezoidal hole by inkjet printing, and after baking, aligning and bonding the substrate 200 with the LED blue light array 300. Among them, it can also further include cleaning the substrate 200, evaporating the reflective layer 210, and other processing or structural formation, which is not further limited in the present application. Specific embodiments Some specific implementation methods will be further introduced below to further explain the technical solution of this application in detail. Specific embodiment 1 The specific preparation method of quantum dot ink is as follows: 25 mL of cyclohexane was used as solvent and 3 g of polyoxyethylene (5) nonylphenyl ether sulfide was used as surfactant and mixed at room temperature. 15 mg of quantum dots (preferably with a quantum dot size greater than 15 nm) dispersed in 0.5 mL of toluene was added to the above mixture, and then 0.5 mL of tetraethyl orthosilicate was added. The mixture was sealed and stirred at room temperature for 24 h. Methanol precipitation solution was added and the precipitate was separated by centrifugation. The obtained precipitate was washed with cyclohexane and n-hexane in turn, and finally dispersed in 10 mL of ethanol.

[0041] 0.1 mL of ammonia water (30%) was added to the above solution to adjust the pH to 9. Then 1 mL of chloroform solution containing 10% trimethoxyoctadecylsilane (OTMS) was added and stirred for 24 hours. The mixture was centrifuged, washed three times with ethanol, and then dissolved in 0.1 mL of chloroform.

[0042] The above solution is uniformly mixed with silicone resin (Dow Corning OE 6550, A: B = 1:4) to form quantum dot ink. According to the requirements of inkjet printing, the viscosity of the ink is adjusted by adjusting the amount of chloroform added, and red quantum dot ink and green quantum dot ink are formed by the above method. In addition, silicon dioxide or titanium dioxide nanoparticles are used with a particle size of about 50-200nm. Take a certain mass and mix it evenly with silicone resin (Dow Corning OE 6550, A: B = 1:4) with a mass fraction of 20%, and adjust the viscosity coefficient by adding a trace amount of chloroform to prepare a blank ink.

[0043] In order to illustrate that the prepared inks have good effects, the present application also provides a micro display prepared based on the above materials, and the specific structure is shown in Figure 2 .

[0044] The specific preparation method of the display device is as follows: A visible light cutoff filter glass substrate with a thickness of 500 microns (having a transmittance of less than 0.15% in the band below 1200 nm) was sequentially placed in a washing liquid, water, acetone and isopropanol, and ultrasonicated for 15 minutes each, and then taken out.

[0045] By using laser processing technology, a trapezoidal hole is etched on the substrate, with the upper opening diameter being about 300 microns and the lower opening diameter being about 200 microns.

[0046] The above substrate is placed in a vacuum coating device to evaporate a 50-100 nm thick metal reflective layer, preferably cheap metals such as Al and Ag.

[0047] Then, the prepared red quantum dot ink, green quantum dot ink and blank ink were printed in the holes in sequence using an inkjet printing device and baked at 110° C. for 30 minutes. After baking, the surface was smooth.

[0048] Align and bond the above-mentioned glass substrate to the Micro-LED blue light array.

[0049] Comparative Example 1 The specific preparation method of quantum dot ink is as follows: 25 mL of cyclohexane was used as solvent and 3 g of polyoxyethylene (5) nonylphenyl ether sulfide was used as surfactant and mixed at room temperature. 15 mg of quantum dots (preferably with a quantum dot size greater than 15 nm) dispersed in 0.5 mL of toluene was added to the above mixture, and then 0.5 mL of tetraethyl orthosilicate was added. The mixture was sealed and stirred at room temperature for 24 h. Methanol precipitation solution was added and the precipitate was separated by centrifugation. The obtained precipitate was washed with cyclohexane and n-hexane in turn, and finally dispersed in 10 mL of ethanol.

[0050] 0.1 mL of ammonia water (30%) was added to the above solution to adjust the pH to 9. Then 1 mL of chloroform solution containing 10% trimethoxyoctadecylsilane (OTMS) was added and stirred for 24 hours. The mixture was centrifuged, washed three times with ethanol, and then dissolved in 0.1 mL of chloroform.

[0051] The above solution was uniformly mixed with silicone resin (Dow Corning OE 6550, A: B = 1:4) to form quantum dot ink. The viscosity of the ink was adjusted by adjusting the amount of chloroform added according to the inkjet printing requirements.

[0052] The specific preparation method of the display device is as follows: A visible light cutoff filter glass substrate with a thickness of 500 microns (having a transmittance of less than 0.15% in the band below 1200 nm) was sequentially placed in a washing liquid, water, acetone and isopropanol, and ultrasonicated for 15 minutes each, and then taken out.

[0053] By using laser processing technology, a trapezoidal hole is etched on the substrate, with the upper opening diameter being about 300 microns and the lower opening diameter being about 200 microns.

[0054] The above substrate is placed in a vacuum coating device to evaporate a 50-100 nm thick metal reflective layer, preferably cheap metals such as Al and Ag.

[0055] Subsequently, an inkjet printing device was used to print unmodified red quantum dot ink, green quantum dot ink and blank ink in the holes in turn, and then a polymer protective layer was printed in turn, and baked at 110°C for 30 minutes. After baking, the surface was smooth.

[0056] Align and bond the above-mentioned glass substrate to the Micro-LED blue light array.

[0057] Comparative Example 2 The quantum dots were not subjected to surface modification in the technical solution of the present application.

[0058] The specific preparation method of the display device is as follows: Place a 500-micron thick ordinary glass substrate (with a transmittance of less than 0.15% in the band below 1200nm) in the washing liquid, water, acetone and isopropanol in turn, and ultrasonicate for 15 minutes each before taking it out. 2. A fixed mass of black matrix material is mixed with 10ml of AZ2020nlof positive photoresist solution with a concentration of 20 wt%, and dispersed by ultrasonic vibration to form a mixed solution. Spin the mixed solution on the blue light LED chip substrate by spin coating at 1000r, 10s, and bake at 110℃ for 5min. After baking, the film thickness is about 8μm and the surface is flat. Use a mask with a pixel size of 300μm*300μm to expose it to ultraviolet light for 15s, then bake it at 100℃ for 5min, and finally develop it with a developer to obtain a patterned film.

[0059] The above substrate is placed in a vacuum coating device to evaporate a 50-100 nm thick metal reflective layer, preferably cheap metals such as Al and Ag.

[0060] Then, the prepared red quantum dot ink, green quantum dot ink and blank ink were printed in the holes in sequence using an inkjet printing device and baked at 110° C. for 30 minutes. After baking, the surface was smooth.

[0061] Align and bond the above-mentioned glass substrate to the Micro-LED blue light array.

[0062] Performance test: The microdisplays obtained from the above different implementations were tested and the experimental data were statistically analyzed. The specific experimental items and results are shown in Table 1.

[0063] Table 1 Test data of microdisplay under different implementation modes It can be seen from the data in Table 1 that the quantum dot ink prepared by the surface modification method of the present application can remain stable and uniform for 24 hours through the samples of Example 1, Comparative Example 1 and Comparative Example 2. By changing the blue light utilization rate in the technical solution of Example 1 of the glass substrate, the inkjet printing time is reduced from the original 1 hour to 0.5 hours. Under blue light irradiation, the fluorescence intensity of the samples of Example 1 and Comparative Example 2 only decreased by 5%, and the stability was greatly improved. It can be seen that the quantum dot ink obtained by the present application scheme not only has improved stability, but also can simplify the process flow and improve production efficiency.

[0064] As can be seen from the foregoing, the present application proposes an innovative method for preparing quantum dot ink, which achieves long-term stable dispersion of quantum dots in a solvent through multi-step surface modification and optimized process parameters. First, the quantum dots are preliminarily modified using a first modification solution containing a polysulfide compound as a surfactant, and the quantum dots are further stabilized by adding tetraethyl orthosilicate to form a first mixed solution. Subsequently, the quantum dots are dispersed in a second dispersion solvent after centrifugal separation and washing to form a quantum dot secondary solution.

[0065] Next, the pH value of the quantum dot secondary solution is adjusted to within the range of 8-11, and a second modification solution containing long-chain alkyl silane and chloroform is added to perform a second surface modification to enhance the dispersion stability of the quantum dots and improve their compatibility with the resin substrate added subsequently. Then, the quantum dots that have undergone the second surface modification are separated from the second mixed solution and dispersed in a third dispersion solvent to form a quantum dot tertiary solution. The purity and dispersibility of the quantum dots are further improved by separation and dispersion again. Finally, the quantum dot tertiary solution is mixed with a fourth dispersion solvent containing a silicone resin to form a quantum dot ink. By adjusting the type and proportion of the silicone resin, the performance parameters of the quantum dot ink, such as viscosity, fluidity, and curing speed, can be optimized.

[0066] In addition, the present application also provides a method for preparing a display device using the above-mentioned quantum dot ink. Through inkjet printing technology, quantum dot inks of different colors are accurately printed on the corresponding positions of different colors of the display device, and after baking treatment, the production efficiency is improved and the production cost is reduced. The quantum dot ink formed by the preparation method of the present application can avoid blockage during the inkjet printing process, so that inkjet printing can be applied more efficiently.

[0067] The above is only a specific implementation of the present application, and any other improvements made based on the concept of the present application are deemed to be within the protection scope of the present application.

Claims

1. A method for preparing quantum dot ink, characterized in that: include: Performing a first surface modification specifically includes: preparing a first modification solution including a first modification solvent and a surfactant, wherein the surfactant includes a polysulfide compound, adding a quantum dot initial solution to the first modification solution, and then adding tetraethyl orthosilicate to form a first mixed solution, wherein the quantum dot initial solution includes quantum dots and a first dispersing solvent; Separating the quantum dots that have undergone the first surface modification from the first mixed solution and dispersing them in a second dispersing solvent to form a quantum dot secondary solution; Performing a second surface modification, specifically comprising: adjusting the pH value of the quantum dot secondary solution to within the range of 8-11, adding a second modification solution after the pH value is adjusted to form a second mixed solution, wherein the second modification solution comprises long-chain alkyl silane and chloroform; Separating the quantum dots that have undergone the second surface modification from the second mixed solution and dispersing them in a third dispersing solvent to form a quantum dot tertiary solution; The quantum dot tertiary solution is mixed with a fourth dispersing solvent to form a quantum dot ink, wherein the fourth dispersing mixed solvent includes an organic silicone resin.

2. The method for preparing quantum dot ink according to claim 1, characterized in that: The quantum dots in the initial quantum dot solution have a size greater than 15 nm.

3. The method for preparing quantum dot ink according to claim 1, characterized in that: After forming the first mixed solution, the method further comprises sealing and stirring the first mixed solution, and after forming the second mixed solution, the method further comprises stirring the first mixed solution, and the stirring time is greater than 12 hours.

4. The method for preparing quantum dot ink according to claim 1, characterized in that: The quantum dots are separated from the solution by centrifugation and washed.

5. The method for preparing quantum dot ink according to claim 1, characterized in that: The volume ratio of the quantum dot tertiary solution to the fourth dispersing solvent is in the range of 1:3-1:

5.

6. The method for preparing quantum dot ink according to claim 1, characterized in that: Adjusting the pH value of the quantum dot secondary solution specifically includes adding ammonia water to the quantum dot secondary solution.

7. The method for preparing quantum dot ink according to claim 1, characterized in that: The method also includes adjusting the viscosity of the quantum dot ink by adjusting the amount of chloroform added.

8. A method for preparing a display device, characterized in that: include: Using the quantum dot ink preparation method according to any one of claims 1 to 7 to obtain quantum dot inks of different colors; Printing the quantum dot ink at positions corresponding to different colors by inkjet printing; The quantum dot ink is baked.

9. The method for manufacturing a display device according to claim 8, characterized in that: Quantum dot inks of different colors include red quantum dot ink and green quantum dot ink, and also include blank ink printed at positions corresponding to blank colors.

10. The method for manufacturing a display device according to claim 9, characterized in that: The method also includes forming a substrate, forming a trapezoidal hole on the substrate, printing quantum dot inks of different colors in the trapezoidal hole by inkjet printing, and after baking, aligning and bonding the substrate to the LED blue light array.

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