A method for improving the luminescence performance of perovskite quantum dot glass and its application

Abstract

The present invention discloses a method for improving the luminescence performance of perovskite quantum dot glass and its application. By adding CaO to regulate the rigidity of the borosilicate glass network structure and reduce structural defects, high-quality full-family CsPbX3 perovskite quantum dots with X=Cl, Br, I are precipitated in the glass. The all-inorganic perovskite quantum dot glass realizes 408-703nm visible spectrum luminescence, wherein the green light CsPbBr3 quantum dot glass and the red light CsPbBr1I2 quantum dot glass have photoluminescence quantum efficiencies of up to 92.86% and 86.01%, respectively. .25%. Thanks to the dense network of inorganic glass that isolates the quantum dots from the external environment, the CsPbX3 quantum dot glass has excellent long-term stability and thermal reversibility. After more than 1400 hours of blue light radiation, water immersion or 85℃ / 85%RH aging tests, the luminous intensity remains above 90% of the initial intensity. In addition, the LCD prepared with CsPbX3 quantum dot glass-silicone composite film exhibits excellent color rendering and more realistic display effects, and its color gamut reaches 115% of the NTSC1953 standard color gamut area.

Description

Technical Field

[0001] The present invention belongs to the field of optoelectronic display technology, and specifically relates to a method for improving the luminescence performance of perovskite quantum dot glass and its application. Background Art

[0002] Perovskite quantum dots are considered to be ideal light conversion materials for the next generation of displays due to their high luminescence quantum efficiency, high color purity, tunable luminescence spectrum, and simple synthesis. However, the inherent ionic crystal properties and large surface energy of perovskite quantum dots have made it impossible for their long-term stability to meet application requirements. In recent years, embedding all-inorganic CsPbX3 (X=Cl, Br, I) perovskite quantum dots into an inorganic glass matrix through in situ crystallization is considered to be an effective way to solve the long-term stability problem. However, unlike wet chemical synthesis methods, the solid glass network usually hinders the Cs + , Pb 2+ and X- ion diffusion or migration. Therefore, perovskite quantum dots are difficult to precipitate from the glass, and structural effects will occur in the perovskite quantum dot lattice, resulting in low absorption and low luminescence quantum efficiency of CsPbX3 quantum dot glass, which cannot meet the requirements of high-brightness liquid crystal display applications. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for improving the luminescence performance of perovskite quantum dot glass and its application. This method can significantly promote the precipitation of high-quality perovskite quantum dots in the glass by regulating the rigidity of the borosilicate glass network structure and reducing structural defects, thereby significantly improving the photoluminescence performance and constructing a high-performance liquid crystal display.

[0004] To achieve the above object, the present invention is implemented through the following technical solutions:

[0005] A method for improving the luminescence performance of perovskite quantum dot glass. CaO is added to raw materials for preparing the perovskite quantum dot glass. The molar percentages of the other raw materials are: SiO2: 20-40 mol%, B2O3: 25-45 mol%, ZnO: 5-15 mol%, Al2O3: 0-5 mol%, CaO: 0-10 mol%, Cs2CO3: 1-8 mol%, PbX2: 2-10 mol%, and NaX: 5-15 mol%, wherein X is Cl, Br, or I.

[0006] Furthermore, the preparation method of perovskite quantum dot glass includes the following steps:

[0007] (1) Weighing SiO2, B2O3, ZnO, Al2O, CaO, Cs2CO3, PbX2, and NaX according to molar percentage, placing the raw materials of perovskite quantum dot glass in an agate mortar, rapidly grinding the raw materials to mix them in the mortar, and then pouring them into an alumina crucible;

[0008] (2) placing an alumina crucible in a high-temperature box furnace to melt the alumina crucible, and then quickly pouring the melt into a copper mold to cool it to obtain a precursor glass;

[0009] (3) The precursor glass is placed in a muffle furnace for heat treatment to induce the in-situ precipitation of CsPbX3 crystals in the glass to obtain CsPbX3 quantum dot glass.

[0010] Furthermore, the melting temperature of the preparation process in step (2) is 1150-1300° C., the heat treatment temperature in step (3) is 480-600° C., and the heat treatment time is 6-10 h.

[0011] A second object of the present invention is to provide a method for improving the luminescence performance of perovskite quantum dot glass to prepare perovskite quantum dot glass.

[0012] A third object of the present invention is to provide a perovskite quantum dot glass for use in preparing optical light-converting film materials.

[0013] Furthermore, perovskite quantum dot glass is applied to the preparation of optical light-conversion film materials. The specific steps are as follows:

[0014] (1) preparing green CsPbBr3 quantum dot glass and red CsPbBr1I2 quantum dot glass, ball-milling them to a particle size of less than 10 μm, and uniformly mixing them in a mass ratio of 2.3:1;

[0015] (2) The uniformly mixed powder is mixed with silica gel at a mass ratio of 1:15, and then the uniformly mixed solution is poured onto the diffusion film and coated with a doctor blade, and cured at 80-90°C for 1-2 hours to finally obtain a perovskite quantum dot glass silica gel optical light conversion film.

[0016] Furthermore, the silica gel used in step (2) includes a main agent and a curing agent, and the mass ratio of the main agent to the curing agent is 10:1.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The present invention provides a method for improving the luminescence performance of perovskite quantum dot glass, which overcomes the effect of the prior art of modifying only one halogen element. CaO is added to the raw materials for preparation, and CaO with low ion field strength is added to the raw materials for preparation. 2+It will destroy the Si-O-Si bond and form weak bonds with non-bridging oxygen anions, thereby destroying the tight glass network. In addition, the introduced free oxygen further destroys the Si-O-Si bridging oxygen structure, resulting in a significant decrease in Q4 and an increase in Q2 and Q3, where Qn represents a group with n bridging oxygen atoms and 4n non-bridging oxygen ions. A small amount of BO3 units is converted into BO4, thereby depolymerizing the glass network structure and providing sufficient space for ion diffusion, resulting in the precipitation of CsPbBr3 quantum dots in the glass. When CaO increases to 10%, the Q4 unit only decreases slightly, but more BO3 is converted into BO4, and BO4 tetrahedrons are connected to SiO4 tetrahedrons, as well as a large amount of Ca 2+ The introduction of Ca fills the depolymerization zone, all of which makes the glass network structure finely aggregate again. In addition, the excess Ca 2+ It will connect with the non-bridging oxygen in the SiO4 tetrahedron by Coulomb force to form a larger anionic group, which hinders the migration of surrounding ions during heating, thereby limiting the in situ nucleation or growth of CsPbBr3 quantum dots in the glass;

[0019] 2. The green and red perovskite quantum dot glasses prepared using the method provided by the present invention have luminescence quantum efficiencies of up to 92.86 and 86.25, respectively, making them well suited to the needs of high-brightness display applications. After more than 1,400 hours of blue light radiation, water immersion, or aging tests at 85°C and 85% RH, the luminescence intensity of the green and red perovskite quantum dot glasses remained above 90% of the initial intensity, sufficient to meet the long-term stability requirements of commercial applications.

[0020] 3. The liquid crystal display constructed by using the optical light-reflecting film combined with titanium ore quantum dot glass and silicone rubber prepared by the method provided by the present invention and coupled with a blue light guide plate as the backlight source is endowed with excellent color rendering performance. After the effect of the color filter, its color gamut reaches 115% of the NTSC 1953 color gamut area, and has broad application prospects in wide color gamut display. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The green CsPbBr3 quantum dot glass prepared by doping with different contents of CaO in Example 1 and the precursor glass with a doping amount of 5 mol% under sunlight (a) and UV light (b) are shown, as well as the corresponding XRD patterns (c);

[0022] Figure 2 The infrared and Raman spectra of the green CsPbBr3 quantum dot glass prepared by doping with different contents of CaO in Example 1;

[0023] Figure 3 Graphs showing the radiative recombination probability and non-radiative probability of the green CsPbBr3 quantum dot glass prepared by doping with different CaO contents in Example 1;

[0024] Figure 4 The images of the red CsPbBr1I2 quantum dot glass prepared by doping with different contents of CaO and the precursor glass with a doping amount of 5 mol% prepared in Example 2 under sunlight (a) and UV light (b), as well as the corresponding XRD patterns (c);

[0025] Figure 5 Long-term stability test results of green CsPbBr3 quantum dot glass and red CsPbBr1I2 quantum dot glass prepared by doping with CaO content of 5 mol% in Example 1 and Example 2;

[0026] Figure 6 The color gamut in the CIE diagram is based on commercial liquid crystal displays (blue triangles), the NSTC 1953 standard (black triangles), and the white light obtained by filtering through a commercial color filter (red triangle) under the excitation of a blue light backlight using the perovskite quantum dot glass-silicone optical conversion film prepared in Example 6. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0028] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0029] The experimental methods in the following examples are conventional methods unless otherwise specified.

[0030] Example 1

[0031] Specific preparation process of CsPbBr3 perovskite quantum dot glass

[0032] (1) Weighing the raw materials with a molar percentage (mol %) of 30SiO2-30B2O3-15ZnO-2Al2O3-5Cs2CO-3PbBr2-15NaBr-5CaO and placing them in an agate mortar;

[0033] (2) The raw materials were quickly ground in an agate mortar for 10 minutes to mix them evenly, then poured into an alumina crucible, and placed in a high-temperature box furnace at 1200°C for melting for 30 minutes. The melt was then quickly poured into a copper mold and cooled to obtain a precursor glass;

[0034] (3) The precursor glass was placed in a muffle furnace and heat treated at 520°C for 10 hours to induce the precipitation of CsPbBr3 quantum dots in the glass, and finally CsPbBr3 quantum dot glass was obtained.

[0035] Example 2

[0036] Specific preparation process of CsPbBr1I2 perovskite quantum dot glass

[0037] (1) Weigh the molar percentage (mol%) of 30SiO2-30B2O3-12ZnO-2Al2O 3- The raw materials of 6Cs2CO3-1PbB r2-2PbI2-5NaBr-10NaI-7.5CaO were placed in an agate mortar;

[0038] (2) The raw materials were quickly ground in an agate mortar for 10 minutes to mix them evenly, then poured into an alumina crucible, and placed in a high-temperature box furnace at 1300°C for melting for 30 minutes. The melt was then quickly poured into a copper mold and cooled to obtain a precursor glass;

[0039] (3) The precursor glass was placed in a muffle furnace and heat treated at 600°C for 6 hours to induce the precipitation of CsPbBr1I2 quantum dots in the glass, and finally CsPbBr1I2 quantum dot glass was obtained.

[0040] Example 3

[0041] Specific preparation process of CsPbCl3 perovskite quantum dot glass

[0042] (1) Weigh the raw materials with a molar percentage (mol %) of 25SiO2-35B2O3-15ZnO-5Al2O3-8Cs2CO3-4PbCl2-10NaCl-2.5CaO and place them in an agate mortar;

[0043] (2) The raw materials were quickly ground in an agate mortar for 10 minutes to mix them evenly, then poured into an alumina crucible, and placed in a high-temperature box furnace at 1200°C for melting for 30 minutes. The melt was then quickly poured into a copper mold and cooled to obtain a precursor glass;

[0044] (3) The precursor glass was placed in a muffle furnace and heat treated at 490°C for 10 hours to induce the precipitation of CsPbCl3 quantum dots in the glass, and finally CsPbCl3 quantum dot glass was obtained.

[0045] Example 4

[0046] Specific preparation process of CsPbCl1Br2 perovskite quantum dot glass

[0047] (1) Weigh the raw materials of 25SiO2-45B2O3-5ZnO-3Al2O3-5Cs2CO3-3PbCl2-6PbBr2-2NaCl-4NaBr-5CaO according to molar percentage and place them in an agate mortar;

[0048] (2) The raw materials were quickly ground in an agate mortar for 10 minutes to mix them evenly, then poured into an alumina crucible, and placed in a high-temperature box furnace at 1200°C for melting for 30 minutes. The melt was then quickly poured into a copper mold and cooled to obtain a precursor glass;

[0049] (3) The precursor glass was placed in a muffle furnace and heat treated at 500°C for 10 hours to induce the precipitation of CsPbCl1Br2 quantum dots in the glass, and finally CsPbCl1Br2 quantum dot glass was obtained.

[0050] Example 5

[0051] Specific preparation process of CsPbI3 perovskite quantum dot glass

[0052] (1) Weighing the raw materials of 20SiO2-40B2O3-10ZnO-3Al2O3-8Cs2CO3-6PbI2-10NaI-10CaO according to molar percentage and placing them in an agate mortar;

[0053] (2) The raw materials were quickly ground in an agate mortar for 10 minutes to mix them evenly, then poured into an alumina crucible, and placed in a high-temperature box furnace at 1200°C for melting for 30 minutes. The melt was then quickly poured into a copper mold and cooled to obtain a precursor glass;

[0054] (3) The precursor glass was placed in a muffle furnace and heat treated at 590°C for 10 hours to induce the precipitation of CsPbI3 quantum dots in the glass, and finally CsPbI3 quantum dot glass was obtained.

[0055] Example 6

[0056] Specific preparation process of CsPbX3 quantum dot glass-silicone optical conversion film

[0057] (1) The green CsPbBr3 prepared in Example 1 and the red CsPbBr1I2 quantum dot glass prepared in Example 2 were ball-milled to a particle size of less than 10 μm and uniformly mixed in a mass ratio of 2.3:1;

[0058] (2) The evenly mixed powder was mixed with silica gel at a mass ratio of 1:15. The silica gel used was divided into a main agent and a curing agent. The mass ratio of the main agent to the curing agent was 10:1. Then the evenly mixed solution was poured onto the diffusion film and coated with a doctor blade. It was cured at 80°C for 2 hours to finally obtain a perovskite quantum dot glass-silicone optical light conversion film.

[0059] Example 7

[0060] Specific preparation process of CsPbX3 quantum dot glass-silicone optical light conversion film

[0061] (1) The green CsPbBr3 prepared in Example 1 and the red CsPbBr1I2 quantum dot glass prepared in Example 2 were ball-milled to a particle size of less than 10 μm and uniformly mixed in a mass ratio of 2.3:1;

[0062] (2) The evenly mixed powder was mixed with silica gel at a mass ratio of 1:15. The silica gel used was divided into a main agent and a curing agent. The mass ratio of the main agent to the curing agent was 10:1. Then the evenly mixed solution was poured onto the diffusion film and coated with a doctor blade. It was cured at 90 ° C for 1 hour to finally obtain a perovskite quantum dot glass-silicone optical light conversion film.

[0063] Example 8

[0064] Specific preparation process of CsPbX3 quantum dot glass-silicone optical light conversion film

[0065] (1) The green CsPbBr3 prepared in Example 1 and the red CsPbBr1I2 quantum dot glass prepared in Example 2 were ball-milled to a particle size of less than 10 μm and uniformly mixed in a mass ratio of 2.3:1;

[0066] (2) The evenly mixed powder was mixed with silica gel at a mass ratio of 1:15. The silica gel used was divided into a main agent and a curing agent. The mass ratio of the main agent to the curing agent was 10:1. Then the evenly mixed solution was poured onto the diffusion film and coated with a doctor blade. It was cured at 85°C for 1.5 hours to finally obtain a perovskite quantum dot glass-silicone optical light conversion film.

[0067] Performance Characterization

[0068] Figure 1 The actual pictures of green CsPbBr3 quantum dot glass prepared in accordance with Example 1 with doping contents of 0 mol%, 2.5 mol%, 5 mol%, 7.5 mol% and 10 mol% CaO and the precursor glass with doping amount of 5 mol% under sunlight (a) and under ultraviolet light (b) and the corresponding XRD images (c) show that the samples without CaO doping still do not precipitate crystalline phase after heat treatment, while the samples with CaO added all show cubic CsPbBr3 crystal phase, proving that CaO can promote the precipitation of CsPbBr3 quantum dots in glass.

[0069] Figure 2 The infrared and Raman spectra of green CsPbBr3 quantum dot glasses prepared in accordance with Example 1 with CaO doping contents of 0 mol%, 2.5 mol%, 5 mol%, 7.5 mol% and 10 mol% respectively show that the addition of an appropriate amount of CaO can reduce the rigidity of the borosilicate glass network, thereby promoting the migration of halogen ions.

[0070] Figure 3 The diagram shows the radiative recombination probability and non-radiative probability of the green CsPbBr3 quantum dot glass prepared in accordance with Example 1 with CaO doping contents of 0 mol%, 2.5 mol%, 5 mol%, 7.5 mol% and 10 mol%. It can be seen from the diagram that adding appropriate CaO can increase the radiative recombination probability and reduce the non-radiative recombination probability of the CsPbBr3 quantum dot glass, thereby achieving the best effect when the CaO content is 5 mol%. When the CaO content is 0 mol%, the radiative recombination probability and non-radiative probability of the green CsPbBr3 quantum dot glass prepared are 0.

[0071] Figure 4 Actual pictures of red CsPbBr1I2 quantum dot glass prepared in accordance with Example 2 with CaO doping contents of 0 mol%, 2.5 mol%, 5 mol%, 7.5 mol% and 10 mol%, and a precursor glass with a doping amount of 5 mol% under sunlight (a) and UV light (b), as well as the corresponding XRD images (c). The XRD images show that the samples without CaO doping still do not precipitate a crystalline phase after heat treatment, while the samples with CaO addition all show cubic CsPbBr1I2 crystal phase, proving that CaO can promote the precipitation of CsPbBr1I2 quantum dots in the glass.

[0072] Figure 5 The long-term stability test results of the green CsPbBr3 quantum dot glass and the red CsPbBr1I2 quantum dot glass prepared by doping with CaO content of 5 mol% in Example 1 and Example 2 prove that the prepared red and green perovskite quantum dot glass has excellent long-term stability and can meet the needs of commercial applications.

[0073] Figure 6 The CIE diagram shows the color gamut of white light obtained by a commercial liquid crystal display (blue triangle), the NSTC 1953 standard (black triangle), and the perovskite quantum dot glass-silicone optical conversion film prepared in Example 6 under blue light backlight excitation after being filtered through a commercial color filter (red triangle). Through the comparison of color gamuts, the perovskite quantum dot glass optical conversion film prepared by the present invention, after being acted upon by a color filter and applied as a backlight source to a liquid crystal display, has a color gamut area of ​​115% of the NTSC color gamut, which is sufficient to meet most requirements for wide color gamut display.

[0074] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. An application of perovskite quantum dot glass in the preparation of optical light-conversion film materials, characterized in that: The steps for applying perovskite quantum dot glass to prepare optical light-reflecting film materials are as follows: (1) Green CsPbBr3 quantum dot glass and red CsPbBr1I2 quantum dot glass were prepared, ball-milled to a particle size of less than 10 μm, and uniformly mixed at a mass ratio of 2.3:1; (2) The uniformly mixed powder is mixed with silica gel at a mass ratio of 1:15, and then the uniformly mixed solution is poured onto the diffusion film and coated with a doctor blade, and cured at 80-90°C for 1-2 hours to finally obtain a perovskite quantum dot glass silica gel optical light conversion film; The preparation method of the perovskite quantum dot glass comprises the following steps: S1. Weigh SiO2, B2O3, ZnO, Al2O3, CaO, Cs2CO3, PbX2, and NaX according to molar percentages, place the raw materials of perovskite quantum dot glass in an agate mortar, quickly grind the raw materials to mix them uniformly in the mortar, and then pour them into an alumina crucible; the molar percentages of the raw materials are SiO2: 20-40 mol%, B2O3: 25-45 mol%, ZnO: 5-15 mol%, Al2O3: 2-5 mol%, Cs2CO3: 5-8 mol%, PbX2: 2-10 mol%, NaX: 5-15 mol%, and CaO: 2.5-10 mol%, wherein X is Cl, Br, or I; S2, placing the alumina crucible in a high-temperature box furnace to melt, and then quickly pouring the melt into a copper mold to cool to obtain a precursor glass; S3. Place the precursor glass in a muffle furnace for heat treatment to induce in-situ precipitation of CsPbX3 crystals in the glass to obtain CsPbX3 quantum dot glass.

2. The use of a perovskite quantum dot glass in the preparation of an optical light-conversion film material according to claim 1, characterized in that: The melting temperature in step S2 is 1150-1300° C., the heat treatment temperature in step S3 is 480-600° C., and the heat treatment time is 6-10 hours.

3. The use of the perovskite quantum dot glass in the preparation of an optical light-conversion film material according to claim 1, characterized in that: The silica gel used in step (2) includes a main agent and a curing agent, and the mass ratio of the main agent to the curing agent is 10:1.

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