Diffusion plate for printing quantum dots and preparation method and application thereof

Abstract

The invention belongs to the technical field of display, and particularly relates to a diffusion plate printed with quantum dots and a preparation method and application of the diffusion plate. A quantum dot precursor is dissolved in water and then mixed with dispersing agents polyvinyl alcohol and n-caprylic alcohol, the mixture is added into an ink matrix, and the ink matrix is formed by mixing bisphenol A type diglycidyl ether and alicyclic epoxy resin. Printing the ink on the surface of a substrate, and performing heat treatment after UV irradiation to obtain the diffusion plate printed with the quantum dots. According to the diffusion plate for printing the quantum dots, the high temperature of a traditional quantum dot diffusion plate during melt extrusion preparation is avoided, so that the quantum dots are prevented from losing efficacy due to the high temperature, and meanwhile, the quantum dots on the prepared diffusion plate can be good in dispersity and stability due to the adoption of the quantum dot precursor ink system.

Description

Technical Field

[0001] The invention belongs to the field of display technology, and in particular relates to a diffusion plate for printing quantum dots and a preparation method and application thereof. Background Art

[0002] Quantum dot diffuser plates have extremely broad application prospects in liquid crystal displays, televisions and other display devices due to their superior performance of high color gamut, low energy consumption, high quantum efficiency and enhanced display effect. However, quantum dot diffuser plates cannot be mass-produced for some reasons. The stability of quantum dots in quantum dot diffuser plates is an important reason hindering their large-scale application. Quantum dots are very sensitive to conditions such as temperature, water, ultraviolet light and oxygen, and are prone to fluorescence quenching in the environment.

[0003] The preparation methods of quantum dot diffusion plates in the prior art mainly include the head layer coating method and the melt extrusion method. The head layer coating method has the problem of edge failure of the quantum dot diffusion plate and high preparation cost. Currently, the more commonly used method is the melt extrusion method. The preparation of quantum dot diffusion plates by the melt extrusion method requires high temperature conditions to melt the blank masterbatch, mix the quantum dots with the blank masterbatch, and extrude them through an extruder. The high temperature required for this process easily causes the quantum dots to fail. CN106918952A discloses a quantum dot diffusion plate, which solves the problem of color difference between the color of the failure area of ​​the cutting edge of the diaphragm of high color gamut quantum dots and the color of other areas, but its preparation temperature reaches 300°C. High temperature will cause thermal quenching of quantum dots and affect their luminous efficiency. CN106950750A discloses a method for producing a quantum dot diffusion plate, which manufactures a quantum dot diffusion plate through an extrusion molding machine, but its extrusion temperature is as high as 270°C to 300°C, and there is a problem of quantum dot failure caused by high temperature.

[0004] In summary, it is necessary to develop a method for preparing quantum dot diffusion plates to avoid high temperature conditions and to prepare quantum dot diffusion plates at a lower temperature, so that quantum dots are less likely to fail during the production process. At the same time, the production process is simple and conducive to large-scale production. Summary of the invention

[0005] In order to solve the problem of quantum dot failure caused by high temperature in the preparation process of the above-mentioned quantum dot diffusion plate, the present invention provides a diffusion plate with printed quantum dots and a preparation method and application thereof.

[0006] In one aspect, the present invention provides a method for preparing a printed quantum dot diffusion plate, comprising the following steps:

[0007] S1, dissolving a quantum dot precursor in water, adding a dispersant, and mixing to obtain a quantum dot precursor solution;

[0008] S2, adding a viscosity modifier and the quantum dot precursor solution described in S1 to the ink matrix, and mixing them to obtain ink;

[0009] S3, printing the ink described in S2 on a substrate, performing UV curing, and obtaining the diffusion plate of the printed quantum dots after heat treatment.

[0010] The preparation method of the present invention is used to evenly disperse the quantum dot precursor in the ink, print it on the surface of the substrate, and perform heat treatment after curing to generate the quantum dots directly on the surface of the substrate, thereby avoiding the thermal failure of the quantum dots caused by melting the quantum dots and masterbatch at high temperature after mixing them by the melt extrusion method, thereby facilitating the stability of the quantum dots and avoiding the agglomeration of the quantum dots during melt extrusion, thereby facilitating the uniform dispersion of the quantum dots. In addition, the present invention prints the ink on the substrate, which can be flexibly adjusted according to demand, realizing the flexible adjustment of dark spots and adjusting the picture.

[0011] Preferably, the heat treatment in step S3 is to heat the temperature to 145-155°C at a heating rate of 48-52°C / h and then keep the temperature constant for 2-2.5h. Heat treatment can make the quantum dot precursor grow into quantum dots. If the heat treatment temperature is too low, the crystallinity of the quantum dots is poor, which is not conducive to improving the optical properties of the quantum dots. If the heat treatment temperature is too high, it will cause the agglomeration of the quantum dots. The heat treatment conditions adopted in the present invention are conducive to the growth of quantum dots. Under this condition, the quantum dot precursor can form uniform and stable quantum dots on the surface of the diffuser. The heat treatment method of the present invention can prepare perovskite quantum dots with good dispersibility and optical properties.

[0012] Preferably, the dispersant in step S1 is a mixture of polyvinyl alcohol and n-octanol in a mass ratio of 1 to 3:8. The combination of polyvinyl alcohol and n-octanol to form a non-ionic surfactant compound system has a synergistic function, so that the quantum dot precursor can be stably dispersed in the ink matrix to avoid agglomeration of quantum dots.

[0013] Preferably, the ink matrix in step S2 is a mixture of bisphenol A diglycidyl ether and alicyclic epoxy resin in a mass ratio of 3 to 5: 1 to 2. Using the mixture as the ink matrix can make the quantum dot precursor stably and evenly dispersed, which is beneficial to the growth of quantum dots in the heat treatment in step S4, so that the diffuser plate for printing quantum dots has the advantages of uniform quantum dot dispersion and good stability.

[0014] Preferably, the quantum dots are perovskite quantum dots. Perovskite quantum dots have a smaller size, quantum confinement effect, and high defect tolerance compared to other quantum dots. The luminescence peak of perovskite quantum dots is narrower than that of other quantum dots, and the optical quality is good. They have excellent photoluminescence quantum yield and high color purity, and show better performance in optoelectronic applications. In addition, the preparation of perovskite quantum dots is relatively simple, and there is no need to wrap and construct a core-shell structure, which is conducive to the large-scale production of the diffusion plate of the printed quantum dots.

[0015] Preferably, the method for adjusting the viscosity in step S2 is to add glycerol as a viscosity modifier. Using glycerol as a viscosity modifier is beneficial to the printing process in step S3, so that the ink maintains good fluidity during the printing process and improves the production efficiency of the diffusion plate for printing quantum dots.

[0016] Preferably, the ink in step S2 contains the following components, in which the ratio of the quantum dot precursor in step S1, water, the dispersant in step S1, the ink matrix in step S2, and the viscosity modifier in step S2 is 4-6:20-30:40-50:450-550:10-15 in terms of mass fractions.

[0017] Preferably, the printing method in step S3 is roller printing, the printing pressure is 90-110 kPa, and the printing speed is 20-25 m / min.

[0018] Preferably, the substrate in step S3 is selected from one of polystyrene (PS), polymethyl methacrylate (PMMA) or polycarbonate (PC).

[0019] In another aspect, the present invention provides use of the quantum dot diffusion plate in preparing a liquid crystal display.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1) The preparation method of the present invention realizes the preparation of quantum dot diffusion plates at relatively low temperatures, avoids the problem of thermal failure of quantum dots under high temperature conditions, avoids the agglomeration of quantum dots, significantly improves the luminescence performance of the diffusion plates printed with quantum dots, and can also adjust the dark spots of the diffusion plates and the picture as needed.

[0022] 2) The quantum dots of the diffusion plate printed with quantum dots prepared by the preparation method of the present invention are evenly dispersed and have good stability.

[0023] 3) The quantum dot-printed diffusion plate of the present invention has the effects of good brightness uniformity and improved optical efficiency.

[0024] 4) The quantum dot diffusion plate prepared by the method of the present invention has the advantages of simple preparation process and easy large-scale production. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below with reference to the examples, which are not intended to limit the scope of the present invention. Unless otherwise specified, the detection method used in the embodiments of the present invention is a conventional method for detection in the art, and the reagents used are all conventional reagents.

[0026] Polyvinyl alcohol was purchased from Sinopharm Chemical Reagent Co., Ltd. with the catalog number 30153160.

[0027] Bisphenol A diglycidyl ether was purchased from Guangdong Wengjiang Chemical Reagent Co., Ltd. with the product number 1675-54-3.

[0028] The alicyclic epoxy resin was purchased from Wuhan Kemik Biopharmaceutical Co., Ltd. with the catalog number 25293-64-5.

[0029] Example 1

[0030] A method for preparing a diffuser plate for printing quantum dots comprises the following steps:

[0031] S1. Prepare quantum dot precursor solution: Dissolve 500 mg of quantum dot precursor in 2.5 ml of water, mix with 3.5 ml of 10% polyvinyl alcohol aqueous solution and 1.5 ml of n-octanol, and treat with ultrasound for 30 min. The quantum dot precursor is a mixture of cesium bromide, cesium carbonate, and zinc bromide in a mass ratio of 1:3:1.

[0032] S2. Preparation of ink: The S1 quantum dot precursor solution was mixed with 40 ml of bisphenol A diglycidyl ether and 10 ml of alicyclic epoxy resin, and after ultrasonication for 15 min, 1 ml of propylene glycol was added to obtain ink.

[0033] S3. Printing: The ink is printed on a 0.5 mm PMMA substrate by roller printing to obtain a diffusion plate with a quantum dot precursor on the surface. The printing pressure is 90 kPa and the printing speed is 20 m / min.

[0034] S4, curing: Place the printed quantum dot diffusion plate on a UV lamp, isolate it from air, and irradiate it with UV for 30 to 40 minutes to cure the ink.

[0035] S5. Heat treatment: Place the quantum dot diffusion plate in an oven, raise the temperature to 145°C at a rate of 48°C / h, and maintain at 145°C for 2.5h.

[0036] S6. Washing: Use ethanol to wash away the uncured ink on the surface of the quantum dot diffusion plate.

[0037] Example 2

[0038] A method for preparing a diffuser plate for printing quantum dots comprises the following steps:

[0039] S1. Prepare quantum dot precursor solution: Dissolve 500 mg of quantum dot precursor in 2.5 ml of water, mix with 3 ml of 10% polyvinyl alcohol aqueous solution and 1 ml of n-octanol, and treat with ultrasound for 35 minutes. The quantum dot precursor is a mixture of cesium bromide, cesium carbonate, and zinc bromide in a mass ratio of 1.5:4:1.

[0040] S2. Preparation of ink: The quantum dot precursor solution described in S1 is mixed with 40 ml of bisphenol A diglycidyl ether and 10 ml of alicyclic epoxy resin, and after ultrasonic treatment for 18 minutes, 1 ml of propylene glycol is added to adjust the viscosity to obtain ink.

[0041] S3. Printing to prepare a quantum dot diffusion plate: Print the ink on a 0.5 mm PMMA substrate by roller printing to obtain a diffusion plate with a quantum dot precursor on the surface. The printing pressure is 100 kPa and the printing speed is 22 m / min.

[0042] S4, curing: Place the printed quantum dot diffusion plate on a UV lamp, isolate it from the air, and irradiate it with UV for 30 minutes to cure the ink.

[0043] S5. Heat treatment: Place the quantum dot diffusion plate in an oven, raise the temperature to 150°C at a rate of 50°C / h, and maintain at 150°C for 2.2h.

[0044] S6. Washing: Use ethanol to wash away the uncured ink on the surface of the quantum dot diffusion plate.

[0045] Example 3

[0046] A method for preparing a diffuser plate for printing quantum dots comprises the following steps:

[0047] S1. Prepare quantum dot precursor solution: Dissolve 500 mg of quantum dot precursor in 2.5 ml of water, mix with 2.5 ml of 10% polyvinyl alcohol aqueous solution and 2.5 ml of n-octanol, and treat with ultrasound for 40 minutes. The quantum dot precursor is a mixture of cesium bromide, cesium carbonate, and zinc bromide in a mass ratio of 2:5:1.

[0048] S2. Preparation of ink: The quantum dot precursor solution described in S1 is mixed with 40 ml of bisphenol A diglycidyl ether and 10 ml of alicyclic epoxy resin, and after ultrasonic treatment for 20 minutes, 1 ml of glycerol is added to adjust the viscosity to obtain ink.

[0049] S3. Printing to prepare a quantum dot diffusion plate: Print the ink on a 0.5 mm PMMA substrate by roller printing to obtain a diffusion plate with a quantum dot precursor on the surface. The printing pressure is 110 kPa and the printing speed is 25 m / min.

[0050] S4, curing: Place the printed quantum dot diffusion plate on a UV lamp, isolate it from the air, and irradiate it with UV for 30 minutes to cure the ink.

[0051] S5. Heat treatment: Place the quantum dot diffusion plate in an oven, raise the temperature to 155°C at a rate of 50°C / h, and maintain at 155°C for 2h.

[0052] S6. Washing: Use ethanol to wash away the uncured ink on the surface of the quantum dot diffusion plate.

[0053] Comparative Example 1

[0054] A method for preparing a printed quantum dot diffusion plate is basically the same as that of Example 2, with the only difference being that the time for maintaining the temperature at 150° C. in step S5 is adjusted to 1 hour.

[0055] Comparative Example 2

[0056] A method for preparing a printed quantum dot diffusion plate is basically the same as that of Example 2, with the only difference being that in step S5, the temperature is adjusted to 100° C. and maintained at 100° C. for 2 h.

[0057] Comparative Example 3

[0058] A method for preparing a printed quantum dot diffusion plate is basically the same as that of Example 2, with the only difference being that the temperature in step S5 is adjusted to be raised to 200° C. and maintained at 200° C. for 2 h.

[0059] Comparative Example 4

[0060] A method for preparing a printed quantum dot diffusion plate is basically the same as that of Example 2, with the only difference being that n-octanol in step S1 is replaced by acetylene glycol polyether.

[0061] Comparative Example 5

[0062] A method for preparing a printed quantum dot diffusion plate is basically the same as that of Example 2, with the only difference being that the polyvinyl alcohol in step S1 is replaced by sodium dodecylbenzene sulfonate.

[0063] Comparative Example 6

[0064] A method for preparing a printed quantum dot diffusion plate is basically the same as that of Example 2, with the only difference being that the alicyclic epoxy resin in step S2 is replaced by a phenolic epoxy resin.

[0065] Comparative Example 7

[0066] A method for preparing a printed quantum dot diffusion plate is basically the same as that of Example 2, with the only difference being that the bisphenol A diglycidyl ether in step S2 is replaced by diglycidyl p-aminophenol.

[0067] Test Example 1: Optical Performance Test of Quantum Dot Diffuser Plate

[0068] The detection method used in this test example refers to GB / T 42976-2023, and the test results of the optical properties of the diffuser plate printed with quantum dots are shown in Table 1.

[0069] Table 1 Optical performance test results of the diffuser with printed quantum dots

[0070]

[0071] From the data in the table, it can be seen that compared with Examples 1 to 3, the color coordinate X offset of Comparative Examples 1 to 3 is -0.0247 to -0.0099, which is greater than -0.0020 to -0.0018 of Examples 1 to 3; the Y offset of Comparative Examples 1 to 3 is -0.0230 to -0.0054, which is greater than -0.0028 to -0.0025 of Examples 1 to 3. It can be seen that the heat treatment temperature and duration during the preparation of the diffusion plate have a great influence on the effectiveness of the quantum dots on the surface of the diffusion plate. The low heat treatment temperature of Comparative Example 2 affects the growth of quantum dots and thus affects their effectiveness. The high heat treatment temperature of Comparative Example 3 causes quantum dots to fail, which in turn leads to a decrease in luminescence performance. The luminescence performance of quantum dots can also be seen from the brightness. The heat treatment conditions of the present invention can prepare quantum dot diffusion plates with better luminescence performance. The brightness of Examples 1 to 3 is 2699 to 2735 cd / m 2 , much larger than the 1833-1973 cd / m of Comparative Examples 1-3 2 The brightness of the nine-grid in Examples 1 to 3 is 92 to 95%, while the brightness of the nine-grid in Comparative Examples 1 to 3 is 67 to 70%. It can be seen that the quantum dot diffusion plates in Examples 1 to 3 have better brightness uniformity, and the quantum dots generated by the heat treatment method of the present invention are more uniform.

[0072] Compared with Examples 1 to 3, the color coordinate X offset of Comparative Examples 4 to 7 is -0.0269 to -0.0149, which is greater than -0.0020 to -0.0018 of Examples 1 to 3; the Y offset of Comparative Examples 4 to 7 is -0.0415 to -0.0219, which is much greater than -0.0028 to -0.0025 of Examples 1 to 3. It can be seen that the dispersant compound system of the present invention (a mixed system formed by compounding polyvinyl alcohol and n-octanol in a ratio of 1 to 3:8) effectively increases the dispersibility of quantum dots. At the same time, the ink matrix system formed by the bisphenol A type diglycidyl ether and alicyclic epoxy resin in a mass ratio of 3 to 5:1 to 2 of the present invention is also beneficial to the uniform dispersion of quantum dots. The brightness of Examples 1 to 3 is 2699 to 2735 cd / m 2 , much larger than 1808~1963cd / m of Comparative Examples 4~7 2 , indicating that the dispersant compound system and the ink matrix compound system of the present invention can both contribute to the luminescence performance of the diffusion plate printed with quantum dots. The brightness of the nine-square grid of Examples 1 to 3 is 92 to 95%, while the brightness of the nine-square grid of Comparative Examples 4 to 7 is 69 to 72%.

[0073] In summary, the quantum dot-printed diffusion plate prepared by the present invention has better optical performance due to the uniformity, stability and quantum efficiency of the quantum dots.

Claims

1. A method for preparing a diffusion plate printed with quantum dots, characterized in that: The following steps are involved: S1, dissolving a quantum dot precursor in water, adding a dispersant, and mixing to obtain a quantum dot precursor solution; S2, adding a viscosity modifier and the quantum dot precursor solution described in S1 to the ink matrix, and mixing them to obtain ink; S3, printing the ink described in S2 on a substrate, performing UV curing, and obtaining the diffusion plate of the printed quantum dots after heat treatment.

2. The preparation method according to claim 1, characterized in that: The heat treatment comprises heating the temperature to 145-155° C. at a heating rate of 48-52° C. / h and then maintaining the temperature for 2-2.5 hours.

3. The preparation method according to claim 1, characterized in that: The dispersant is a mixture of polyvinyl alcohol and n-octanol in a mass ratio of 1 to 3:

8.

4. The preparation method according to claim 1, characterized in that: The ink matrix is ​​a mixture of bisphenol A diglycidyl ether and alicyclic epoxy resin in a mass ratio of 3-5:1-2.

5. The preparation method according to claim 1, characterized in that: In terms of mass fractions, the ratio of the quantum dot precursor in step S1, the water in step S1, the dispersant in step S1, the ink matrix in step S2, and the viscosity modifier in step S2 is 4-6:20-30:40-50:450-550:10-15.

6. The preparation method according to claim 1, characterized in that: The quantum dot precursor is a mixture of cesium bromide, cesium carbonate and zinc bromide in a mass ratio of 1 to 1.5:3 to 5:

1.

7. The preparation method according to claim 1, characterized in that: The printing in step S3 is roller printing, the printing pressure is 90-110 kPa, and the printing speed is 20-25 m / min.

8. The preparation method according to claim 1, characterized in that: The viscosity modifier is glycerol.

9. A diffusion plate with printed quantum dots prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the quantum dot-printed diffusion plate according to claim 9 in preparing a liquid crystal display.

Images