A method for constructing Ag-In-Ga-S quantum dot backlight film

Abstract

This invention discloses a method for constructing an Ag-In-Ga-S quantum dot backlight film. The method involves taking an AIGS quantum dot stock solution, performing post-processing to obtain AIGS quantum dot powder; weighing a polymer and adding it to a non-polar solvent, heating and stirring to dissolve it, thus obtaining a polymer solution; mixing the AIGS quantum dot powder and polymer solution until homogeneous, pouring the mixture onto a flat plate, and coating it with a coating machine to form a uniform thickness initial quantum dot film; placing the film in an oven and drying it at a specific temperature for a specific time to obtain the AIGS quantum dot backlight film. This invention utilizes AIGS quantum dots as a photoluminescent material, mixing different types of AIGS quantum dot powder with a polymer solution, and drying to obtain the AIGS quantum dot backlight film. This method improves the fluorescence intensity of the AIGS quantum dot backlight film while reducing its blue light transmittance, making it an ideal choice for next-generation lighting and high-definition display applications.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterials technology, specifically relating to a method for constructing an Ag-In-Ga-S quantum dot backlight film. Background Technology

[0002] Traditional LCD displays use cold cathode fluorescent lamps (CCFLS) as backlights. Due to their poor light emission and inaccurate color reproduction, they suffer from low color fidelity. As people's living standards improve, new demands are being placed on high-definition displays. In recent years, quantum dots (such as cadmium sulfide quantum dots) have replaced traditional phosphors due to their superior luminescent properties. However, the toxicity (cadmium element) and complex manufacturing process of these quantum dots limit their application in lighting and backlighting displays.

[0003] Cadmium- and lead-free Group I-III-VI quantum dots, as a novel environmentally friendly luminescent material, have shown great potential in improving the luminous efficiency and color reproduction of displays due to their high photoluminescence quantum yield, high spectral tunability, and stability, and are gradually becoming an important research direction in the field of luminescent displays. However, current research on these quantum dots, especially Ag-In-Ga-S (AIGS) quantum dots, is still in its early stages, and research on their quantum dot backlight films is even more scarce. Studies addressing issues such as high blue light transmittance and low fluorescence intensity in backlight films are almost non-existent.

[0004] Therefore, a method for constructing Ag-In-Ga-S quantum dot backlight films is needed to solve the above problems. Summary of the Invention

[0005] Purpose of the invention: To address the problems existing in the prior art, the present invention provides a method for constructing Ag-In-Ga-S quantum dot backlight films.

[0006] A method for constructing an Ag-In-Ga-S quantum dot backlight film includes the following steps:

[0007] Step 1: Take the Ag-In-Ga-S quantum dot stock solution and centrifuge it;

[0008] Step 2: Take the supernatant obtained by centrifugation, add precipitant to it, mix well and then centrifuge a second time;

[0009] Step 3: Disperse the precipitate obtained from the second centrifugation in a dispersant, add a precipitant, mix well, and then centrifuge three times.

[0010] Step 4: Place the precipitate from the three centrifugations into an oven and dry it at a certain temperature for a period of time to obtain quantum dot powder;

[0011] Step 5: Take a certain amount of polymer and mix it with a non-polar solvent and heat it to obtain a polymer solution;

[0012] Step 6: Take a certain amount of the prepared quantum dot powder and mix it with the polymer solution prepared in Step 5 for a certain period of time to obtain a uniform and stable quantum dot polymer solution.

[0013] Step 7: Pour the quantum dot polymer solution obtained in Step 6 onto a flat plate and coat it with a coating machine to obtain a quantum dot initial film of uniform thickness.

[0014] Step 8: Place the initial quantum dot film in an oven and dry it at a certain temperature for a certain time to obtain the AIGS quantum dot backlight film.

[0015] Furthermore, the Ag-In-Ga-S quantum dot stock solution mentioned in step 1 is an AIGS quantum dot stock solution, an AIGS@GaS quantum dot stock solution, or an AIGS@ZnS quantum dot stock solution.

[0016] Furthermore, in steps 1, 2, and 3, the centrifugation speed is 6000 rpm to 11000 rpm, and the centrifugation time is 3 min to 8 min.

[0017] Furthermore, the precipitant mentioned in step 2 is anhydrous ethanol, a polar solvent, and its volume is 2 to 10 times that of the supernatant.

[0018] Furthermore, the dispersant in step 3 is toluene, n-hexane, or n-octane, and the volume ratio of the dispersant to the Ag-In-Ga-S quantum dot stock solution is 0.5–2 mL: 2–5 mL; the precipitant is anhydrous ethanol, a polar solvent, and its volume is 2–10 times that of the dispersant.

[0019] Furthermore, in step 4, the quantum dot precipitation drying temperature is 20℃~80℃ and the drying time is 2h~8h, while in step 8, the drying temperature is 20℃~100℃ and the drying time is 2min~12h.

[0020] Furthermore, the polymer mentioned in step 5 is methyl methacrylate (PMMA), polyvinyl alcohol (PS), or polyethylene oxide (PEO), and the mass-to-volume ratio of the polymer to the Ag-In-Ga-S quantum dot stock solution is 0.25g to 1.25g: 2 to 5mL.

[0021] Furthermore, the nonpolar solvent mentioned in step 5 is n-hexane, n-octane, or toluene, and the volume ratio of the nonpolar solvent to the Ag-In-Ga-S quantum dot stock solution is 2-5 mL: 2-5 mL.

[0022] Furthermore, in step 6, the mass-to-volume ratio of the quantum dot powder to the Ag-In-Ga-S quantum dot stock solution is 0.02–0.08 g: 2–5 mL, and the mixing time is 10–30 min.

[0023] Furthermore, the coating thickness described in step 7 is 100μm to 1200μm.

[0024] Invention principle: This invention differs from the traditional method of preparing backlight film by mixing cadmium-based and lead-based quantum dots with polymers. Instead, it uses cadmium- and lead-free AIGS quantum dots to mix with a polymer solution and stir evenly. Through processes such as coating and drying, a uniform and stable AIGS quantum dot backlight film is obtained.

[0025] Beneficial effects: The construction method of the Ag-In-Ga-S quantum dot backlight film of this invention is simple to operate, has a high reproducibility, and is conducive to large-scale industrial production, providing a new potential material for the backlight display field. The construction of an AIGS quantum dot backlight film was achieved by mixing AIGS quantum dot powder with a nonpolar polymer solution, followed by coating and drying to obtain an AIGS quantum dot backlight film. By changing the amount of quantum dot powder added, the blue light transmittance was reduced, and the fluorescence intensity of the backlight film was improved. Attached Figure Description

[0026] Figure 1 These are X-ray diffraction patterns of Embodiment 1 and Comparative Example 3 of the present invention;

[0027] Figure 2 This is a comparison chart of the transmittance of Embodiment 1 of the present invention with Comparative Examples 1, 2, and 3;

[0028] Figure 3 This is a comparison chart of transmittance of Embodiments 1, 2, and 3 of the present invention, and Comparative Example 3.

[0029] Figure 4 This is a comparison diagram of the emission spectra of Embodiment 1 and Comparative Examples 1 and 2 of the present invention;

[0030] Figure 5 This is a comparison diagram of the emission spectra of Embodiment 1 and Embodiments 2 and 3 of the present invention;

[0031] Figure 6 This is an LED image under blue light (450nm) excitation according to Embodiment 1 of the present invention;

[0032] Figure 7 This is an LED image under blue light (450nm) excitation according to Embodiment 2 of the present invention;

[0033] Figure 8 This is an LED image under blue light (450nm) excitation according to Embodiment 3 of the present invention;

[0034] Figure 9These are emission spectrum comparison diagrams of Embodiments 1 and 4 of the present invention. Detailed Implementation

[0035] The preferred embodiments of the present invention will now be described in conjunction with the accompanying drawings, which will more clearly and completely illustrate the technical solution of the present invention.

[0036] Example 1

[0037] The method for constructing the Ag-In-Ga-S quantum dot backlight film of the present invention includes the following steps:

[0038] Step 1: Take 5 mL of AIGS@GaS quantum dot stock solution, centrifuge at 8000 rpm for 5 min, obtain 2 mL of the supernatant, add 10 mL of anhydrous ethanol, centrifuge again at 8000 rpm for 5 min, obtain the lower precipitate, take 2 mL of toluene to disperse it, add 10 mL of anhydrous ethanol and mix well, centrifuge a third time at 8000 rpm for 5 min, take the lower precipitate, and dry it in an oven at 60℃ for 2 h to obtain powdered quantum dots.

[0039] Step 2: Take 1g of PMMA and 4mL of toluene, mix and heat at 90℃ until dissolved, then cool.

[0040] Step 3: Add 0.08g of AIGS@GaS quantum dot powder to the toluene solution of PMMA and stir until homogeneous.

[0041] Step 4: The AIGS@GaS quantum dots obtained in Step 3 are poured onto a glass plate and coated with PMMA toluene solution. The mixture is then placed in an oven to dry, thus obtaining the AIGS@GaS quantum dot backlight film.

[0042] Example 2

[0043] The process is the same as in Example 1, except that the 0.08g of powdered quantum dots in step 3 is replaced with 0.02g, while other conditions remain the same.

[0044] Example 3

[0045] The process is the same as in Example 1, except that the 0.08g of powdered quantum dots in step 3 is replaced with 0.04g, while other conditions remain the same.

[0046] Example 4

[0047] The process is the same as in Example 1, except that the AIGS@GaS quantum dot stock solution in step 1 is replaced with AIGS quantum dot stock solution, while other conditions remain the same.

[0048] Comparative Example 1

[0049] The process is the same as in Example 1, except that the quantum dot precipitate obtained by centrifuging the AIGS@GaS quantum dot stock solution in step 1 is dried in an oven and the resulting powder is mixed with a toluene solution of PMMA.

[0050] Comparative Example 2

[0051] The process is the same as in Example 1, except that the quantum dot precipitate obtained by secondary centrifugation of the AIGS@GaS quantum dot stock solution in step 1 is dried in an oven and the resulting powder is mixed with a toluene solution of PMMA.

[0052] Comparative Example 3

[0053] The process was the same as that of Comparative Example 1, except that no powdered quantum dots were added, while other conditions remained the same.

[0054] Depend on Figure 1 It can be seen that drying the quantum dots and adding them to a toluene solution of PMMA does not affect the original crystal structure of the quantum dots, and the main diffraction peaks of the resulting quantum dots are all located within the range of AgInS2 and AgGaS2 diffraction peaks, indicating that the synthesized product is Ag-In-Ga-S quaternary quantum dots.

[0055] Depend on Figure 2 It can be seen that the blue light transmittance of the quantum dot backlight film made from quantum dot powder that has been centrifuged three times decreased from 30% after centrifugation only once to 21%.

[0056] Depend on Figure 3 It can be seen that the blue light (450nm) transmittance of the quantum dot backlight film made of quantum dot powder with increased quantum dot content is reduced from 85% to 21%.

[0057] Depend on Figure 4 It can be seen that, under the same excitation light (480nm) and the same slit, the quantum dot backlight film made from powder quantum dots that have undergone three centrifugations has the highest fluorescence intensity.

[0058] Depend on Figure 5 It can be seen that, under the same excitation light (480nm) and the same slit, the quantum dot color conversion film prepared with 0.08g of powdered quantum dots has the highest fluorescence intensity.

[0059] Depend on Figure 6 As can be seen, in Example 1, the AIGS quantum dot backlight film with 0.08g of quantum dots added achieved 545nm peak emission after being excited by a blue light chip, and the blue light emission peak was relatively low.

[0060] Depend on Figure 7As can be seen, in Example 3, after adding 0.04g of quantum dots to the AIGS quantum dot backlight film, 545nm peak emission was achieved after being excited by the blue light chip, and the blue light peak position was relatively high.

[0061] Depend on Figure 8 As can be seen, in Example 2, the AIGS quantum dot backlight film with 0.02g of quantum dots added achieved weak 545nm peak emission after being excited by a blue light chip, and the blue light peak position was relatively high.

[0062] Depend on Figure 9 As can be seen, after adding different types of AIGS quantum dots, the backlight films in Examples 1 and 4 achieved different peak emission positions. The emission peak positions of AIGS@GaS and AIGS quantum dot backlight films were 545nm and 630nm, respectively, exhibiting relatively standard green and red fluorescence, laying the foundation for lighting and display applications.

[0063] In summary, this invention provides a method for constructing an Ag-In-Ga-S quantum dot backlight film. By adjusting parameters such as the number of post-processing steps, drying time, drying temperature, and quantum dot type, the fluorescence intensity of the backlight film is increased while its blue light transmittance is reduced.

Claims

1. A method for constructing an Ag-In-Ga-S quantum dot backlight film, comprising the following steps: Step 1: centrifuging Ag-In-Ga-S quantum dot stock solution; the Ag-In-Ga-S quantum dot stock solution in step 1 is AIGS quantum dot stock solution, AIGS@GaS quantum dot stock solution or AIGS@ZnS quantum dot stock solution; Step 2: taking the supernatant prepared by centrifugation, adding a precipitant thereto, and then performing secondary centrifugation after mixing uniformly; Step 3: dispersing the precipitate prepared by secondary centrifugation in a dispersant, adding a precipitant thereto, and then performing tertiary centrifugation after mixing uniformly; Step 4: placing the precipitate prepared by tertiary centrifugation into an oven, drying at a certain temperature for a period of time, and obtaining quantum dot powder; Step 5: mixing a certain amount of polymer with a non-polar solvent and heating to prepare a polymer solution; the polymer in step 5 is polymethyl methacrylate (PMMA); Step 6: mixing a certain amount of quantum dot powder prepared with the polymer solution prepared in step 5 for a certain period of time to obtain a uniform and stable quantum dot polymer solution; Step 7: pouring the quantum dot polymer solution prepared in step 6 on a flat plate, and performing blade coating by a coating machine to obtain a quantum dot initial film with uniform thickness; Step 8: placing the quantum dot initial film in an oven, drying at a certain temperature for a period of time, and preparing an AIGS quantum dot backlight film.

2. The method for constructing the Ag-In-Ga-S quantum dot backlight film according to claim 1, characterized in that, The rotation speed of centrifugation in steps 1, 2 and 3 is 6000 rpm-11000 rpm, and the centrifugation time is 3 min-8 min.

3. The method for constructing the Ag-In-Ga-S quantum dot backlight film according to claim 1, characterized in that, The precipitant in step 2 is polar solvent anhydrous ethanol, and the volume is 2-10 times that of the supernatant.

4. The method for constructing the Ag-In-Ga-S quantum dot backlight film according to claim 1, characterized in that, The dispersant in step 3 is toluene, n-hexane or n-octane, and the volume ratio of the dispersant to the Ag-In-Ga-S quantum dot stock solution is 0.5-2 mL:2-5 mL; the precipitant is polar solvent anhydrous ethanol, and the volume is 2-10 times that of the dispersant.

5. The method for constructing the Ag-In-Ga-S quantum dot backlight film according to claim 1, characterized in that, The drying temperature of the quantum dot precipitate in step 4 is 20℃-80℃, and the drying time is 2 h-8 h; the drying temperature in step 8 is 20℃-100℃, and the drying time is 2 min-12 h.

6. The method for constructing the Ag-In-Ga-S quantum dot backlight film according to claim 1, characterized in that, The mass-volume ratio of the polymer to the Ag-In-Ga-S quantum dot stock solution in step 5 is 0.25 g-1.25 g:2-5 mL.

7. The method for constructing the Ag-In-Ga-S quantum dot backlight film according to claim 1, characterized in that, The non-polar solvent in step 5 is n-hexane, n-octane or toluene, and the volume ratio of the non-polar solvent to the Ag-In-Ga-S quantum dot stock solution is 2-5 mL:2-5 mL.

8. The method for constructing the Ag-In-Ga-S quantum dot backlight film according to claim 1, characterized in that, The mass-volume ratio of the quantum dot powder to the Ag-In-Ga-S quantum dot stock solution in step 6 is 0.02-0.08 g:2-5 mL, and the mixing time is 10-30 min.

9. The method for constructing the Ag-In-Ga-S quantum dot backlight film according to claim 1, characterized in that, The blade coating thickness in step 7 is 100 μm-1200 μm.

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