Panchromatic conversion LED device based on high-stability cellulose acetate perovskite quantum dots

Abstract

The invention relates to the technical field of quantum dot materials, and aims to provide a one-step method for preparing a high-stability cellulose acetate perovskite quantum dot material and a method for preparing a panchromatic conversion LED device by modulating halogen components. A green light CA-G-PQDs film, a red light CA-R-PQDs film and a blue light CA-B-PQDs film are generated in one step by an improved ligand-assisted precipitation method. The material not only has long quantum average life and high exciton binding energy, but also provides possibility for preparation of monochromatic conversion devices due to good material performance. A PQDs film is packaged on a commercial ultraviolet chip, a monochromatic conversion device is successfully assembled, and considerable luminous efficiency is achieved. The color gamut of the color conversion device reaches 132.3% of the NTSC standard, and excellent stability can still be kept after the color conversion device is continuously lightened for 200 hours.

Description

Technical Field

[0001] This invention patent relates to the technical field of quantum dot materials, and particularly to a full-color conversion LED device based on highly stable cellulose acetate perovskite quantum dots. Background Art

[0002] In order to achieve monochromatic LED device lighting and solve problems such as the difficulty in synthesizing red and blue quantum dots and their short lifespan, since the crystal structures of red and blue PQDs are doped with other halogen components, their crystal structures are less stable than those of green PQDs, which hinders the practical application of PQDs. At the same time, in the research progress of cellulose-based monochromatic conversion LED lighting devices, most are to cover a layer of red phosphor on an lnGaN blue chip to excite green cellulose-based PQDs materials to prepare white LED display devices, and there is still great research potential in the application of trichromatic monochromatic conversion display devices. Currently, the existing green conversion LED display devices have problems of low luminous efficiency and short working time. At a working current of 20 mA, the luminous efficiency is 42.2 lm / W, and the emission intensity drops significantly to 65% after 480 min of continuous lighting, presenting practical application defects.

[0003] Compared with traditional quantum dots and rare earth fluorescent materials, perovskite quantum dots exhibit excellent optical properties, and their preparation methods are simple and low-cost. However, whether it is metal-organic hybrid perovskite quantum dots or all-inorganic perovskite quantum dots, the problem of poor stability is still significant, limiting their application in complex environments. Due to its ionic compound characteristics, perovskite is prone to ion migration in natural environments, continuous irradiation, and polar solvents such as water. Ion exchange makes the spectral tuning of perovskite easier, but also leads to the instability of the structure of mixed-halide perovskite itself. In the prior art, ligands such as alkanes with different chain lengths, conjugated structures, silanes, and inorganics are used to solve problems such as crystal defects, stability, optical regulation, charge transport, and film formation. However, the addition of ligands often introduces complex synthesis steps and chemical environments, increasing the difficulty and cost of the synthesis process, and may also affect the optical properties and subsequent processing applications of quantum dots. Against this background, synthesizing high-quality quantum dots using simplified synthesis methods has become an important research direction.

[0004] A large number of research results have been achieved in the application of cellulose and its derivatives in perovskite materials, mainly reflected in being used as a substrate film, reinforcing material, and auxiliary role in the crystal growth process. In the prior art, cellulose nanocrystal (CNC) colloidal materials can effectively mix with CH3NH3PbBr3 precursors and spontaneously form perovskite crystals during the film-forming process. This film has a light absorption efficiency of 91% and strong green light emission (518 nm).

[0005] As a natural polymer material with good biodegradability and film-forming properties, cellulose acetate (CA) has been widely used in perovskite solar cells in recent years due to its moisture resistance, heat resistance, good optical transparency, and ultraviolet shielding potential. However, there is no report on directly using cellulose acetate and perovskite quantum dots to prepare perovskite quantum dots by a one-step film-forming method to improve the stability of perovskite quantum dots and then fabricating a full-color conversion LED device. Summary of the Invention

[0006] To solve the above technical problems, the object of the present invention is to provide a method for preparing highly stable cellulose acetate perovskite quantum dot materials by a one-step method and fabricating a full-color conversion LED device by modulating the halogen composition. Using cellulose acetate (CA) as an inorganic matrix, green CA-G-PQDs films, red CA-R-PQDs films, and blue CA-B-PQDs films are generated in one step by improving the ligand-assisted precipitation method. Not only does it have relatively long average quantum lifetimes of CA-G-PQDs (τ ave = 16.895 ns), CA-R-PQDs (τ ave = 4.439 ns), CA-B-PQDs (τ ave = 3.480 ns) and high exciton binding energies of E b = 80.74 meV (green light), E b = 68.39 meV (red light), E b = 205. meV (blue light), but also the good material properties provide the possibility for the preparation of monochromatic conversion devices. Encapsulating the PQDs film on a commercial ultraviolet chip, monochromatic conversion devices are successfully assembled, and CA-R-PQDs, CA-G-PQDs, and CA-B-PQDs have considerable luminous efficiencies of 28.78 lm / W, 48.41 lm / W, and 12.78 lm / W. The color gamut of the color conversion device reaches 132.3% of the NTSC standard and still maintains excellent stability after continuous lighting for 200 hours (84.8%, 76.6%, and 73.1% of the initial intensity after 200 h).

[0007] The object of the present invention can be achieved by the following technical solutions:

[0008] The present invention provides a full-color conversion LED device based on highly stable cellulose acetate perovskite quantum dots, and the full-color conversion LED device includes a green conversion LED device with a CA-G-PQDs film, a red conversion LED device with a CA-R-PQDs film, and a blue conversion LED device with a CA-B-PQDs film.

[0009] Further, the preparation method of the green conversion LED device with the CA-G-PQDs film includes the following steps:

[0010] Synthesis of X1.CsPbBr3 precursor solution: Dissolve CsBr and PbBr2 in DMF, stir magnetically at room temperature until the solution is completely transparent, seal and set aside;

[0011] Preparation of X2.CA solution: Dissolve cellulose acetate powder in DMF, seal and set aside;

[0012] Preparation of X3.CA-G-PQDs film: Add the precursor solution in step X1 to the CA solution in step X2, stir magnetically at room temperature, perform vacuum filtration and then vacuum drying to obtain the CA-G-PQDs film;

[0013] X4.Encapsulate the CA-G-PQDs film with a thickness of 0.15 mm - 0.19 mm on a commercial 395 nm UV chip, connect it to the circuit and fix it with hot melt adhesive to obtain the CA-G-PQDs film green conversion LED device.

[0014] Furthermore, the preparation method of the CA-R-PQDs film red conversion LED device includes the following steps:

[0015] Y1.CsPbBr 1.5 Cl 1.5 Synthesis of precursor solution: Dissolve CsBr, PbBr2, CsCl and PbCl2 in DMF, stir magnetically at room temperature until the solution is completely transparent, seal and set aside;

[0016] Preparation of Y2.CA solution: Dissolve cellulose acetate powder in DMF, seal and set aside;

[0017] Preparation of Y3.CA-R-PQDs film: Add the precursor solution in step Y1 to the CA solution in step Y2, stir magnetically at room temperature, perform vacuum filtration and then vacuum drying to obtain the CA-R-PQDs film;

[0018] Y4.Encapsulate the CA-R-PQDs film with a thickness of 0.15 mm - 0.19 mm on a commercial 395 nm UV chip, connect it to the circuit and fix it with hot melt adhesive to obtain the CA-R-PQDs film red conversion LED device.

[0019] Furthermore, the preparation method of the CA-B-PQDs film blue conversion LED device includes the following steps:

[0020] Synthesis of Z1.CsPbBrI2 precursor solution: Dissolve CsBr and PbI2 in DMF, stir magnetically at room temperature until the solution is completely transparent, seal and set aside;

[0021] Preparation of Z2.CA solution: Dissolve cellulose acetate powder in DMF, seal and reserve for later use;

[0022] Preparation of Z3.CA-B-PQDs film: Add the precursor solution in step Z1 to the CA solution in step Z2, stir magnetically at room temperature, perform vacuum filtration and then vacuum drying to obtain the CA-B-PQDs film;

[0023] Z4. Encapsulate the CA-B-PQDs film with a thickness of 0.15 mm - 0.19 mm on a commercial 395 nm UV chip, connect it to the circuit and fix it with hot melt adhesive to obtain the CA-B-PQDs film blue conversion LED device.

[0024] Furthermore, in step X1, the molar ratio of CsBr to PbBr2 is 1:1, and the solid-liquid ratio of the CsPbBr3 precursor solution is 14 - 15 g / L.

[0025] Furthermore, in step Y1, the molar ratio of CsBr, PbBr2, CsCl to PbCl2 is 1:1:1:1, and the solid-liquid ratio of the CsPbBr 1.5 Cl 1.5 precursor solution is 20 - 21 g / L.

[0026] Furthermore, in step Z1, the molar ratio of CsBr to PbI2 is 1:1, and the solid-liquid ratio of the CsPbBrI2 precursor solution is 16 - 17 g / L.

[0027] Furthermore, in steps X2, Y2 and Z2, the concentration of the CA solution is 2 wt%.

[0028] Furthermore, in steps X3, Y3 and Z3, the volume ratio of the precursor solution to the CA solution is 2.5:10.

[0029] Furthermore, the rotation speed of the magnetic stirring is 600 rpm, and the time of the magnetic stirring is 3 h.

[0030] Furthermore, the time of the vacuum filtration is 24 h; the vacuum drying is carried out at 45 °C for 24 h under a vacuum degree of 0.1 atmospheres.

[0031] The beneficial effects that can be produced by this application are as follows:

[0032] In the present invention, green light CA-G-PQDs film, red light CA-R-PQDs film and blue light CA-B-PQDs film are generated in one step by improving the ligand-assisted precipitation method. It not only has a relatively long quantum average lifetime for CA-G-PQDs (τ ave = 16.895 ns), CA-R-PQDs (τ ave= 4.439 ns), CA-B-PQDs (τ ave = 3.480 ns) and high exciton binding energy E b = 80.74 meV (green light), E b = 68.39 meV (red light), E b = 205. meV (blue light). The good material properties make it possible to fabricate monochromatic conversion devices. By encapsulating PQDs film on commercial UV chips, monochromatic conversion devices are successfully assembled, and CA-R-PQDs, CA-G-PQDs and CA-B-PQDs have considerable luminous efficiencies of 28.78 lm / W, 48.41 lm / W and 12.78 lm / W. The color gamut of the color conversion device reaches 132.3% of the NTSC standard and still maintains excellent stability after continuous lighting for 200 hours (84.8%, 76.6% and 73.1% of the initial intensity are maintained after 200 h). BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the TEM image of the CA-G-PQDs film in the embodiment of the present invention. The inset is the statistical chart of the quantum dot size distribution under a 20 nm TEM image.

[0034] Figure 2 This is the TEM image of the CA-R-PQDs film and CA-B-PQDs film in the embodiment of the present invention. (a), (c), (e) are the photos of CA-R-PQDs at 100 nm, 20 nm, 5 nm respectively, and the inset therein is the size distribution diagram of CA-R-PQDs; (b), (d), (f) are the photos of CA-B-PQDs at 50 nm, 20 nm, 5 nm respectively, and the inset therein is the size distribution diagram of CA-B-PQDs.

[0035] Figure 3 This is the X-ray diffraction spectrum of the CA-G-PQDs film in the embodiment of the present invention. The left inset is the photo under 365 nm ultraviolet light excitation, and the right is its high-resolution TEM photo.

[0036] Figure 4 This is the X-ray diffraction spectrum of the CA-R-PQDs film, CA-B-PQDs film and CA film in the embodiment of the present invention.

[0037] Figure 5 This is the PL spectrum of the CA-G-PQDs film, CA-R-PQDs film and CA-B-PQDs film in the embodiment of the present invention. The inset therein is the photo of ambient light and ultraviolet excitation (the scale is 2 cm).

[0038] Figure 6Picture of the simple monochromatic conversion LED device prepared in the embodiment of the present invention.

[0039] Figure 7 Photographs of the light output of three monochromatic conversion LED devices in the embodiment of the present invention after 0 hours, 100 hours, and 200 hours.

[0040] Figure 8 Electroluminescence intensity decay of CA-R-PQDs-LED, CA-G-PQDs-LED, and CA-B-PQDs-LED in the embodiment of the present invention at different operating times.

[0041] Figure 9 EL spectra (a) and color gamut coordinates (with NTSC as the standard color gamut coordinates) (b) of CA-R-PQDs-LED, CA-G-PQDs-LED, and CA-B-PQDs-LED devices in the embodiment of the present invention. Detailed implementation manners

[0042] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present application.

[0043] In the following embodiments, the cellulose acetate powder is purchased from Shanghai Macklin Biochemical Technology and contains 9.8 wt% acetyl group and 3.5 wt% hydroxyl group.

[0044] Embodiment 1

[0045] A full-color conversion LED device based on highly stable cellulose acetate perovskite quantum dots, the full-color conversion LED device includes a CA-G-PQDs film green conversion LED device, a CA-R-PQDs film red conversion LED device, and a CA-B-PQDs film blue conversion LED device.

[0046] The preparation method of the CA-G-PQDs film green conversion LED device is as follows:

[0047] X1. Synthesis of CsPbBr3 precursor solution: Dissolve 0.5 mmol CsBr and 0.5 mmol PbBr2 in 20 mL of DMF respectively, set the magnetic stirrer to 600 rpm, stir at room temperature for 3 hours until the solution is completely transparent, and store it sealed in a sample bottle for subsequent use;

[0048] Preparation of X2.CA solution: Under normal temperature conditions, dissolve cellulose acetate powder in DMF to prepare a CA solution with a concentration of 2 wt%, and seal the prepared CA solution with sealant for later use;

[0049] Preparation of X3.CA-G-PQDs film: Add 2.5 mL of the precursor solution in step X1 to 10 mL of the CA solution in step X2, stir magnetically at 600 rpm at room temperature for 3 hours, vacuum filter for 24 hours, and then dry in a vacuum drying oven at 45 °C under a vacuum of 0.1 atm for 24 hours to obtain the CA-G-PQDs film;

[0050] X4. Encapsulate the CA-G-PQDs film with a thickness of 0.17 mm on a commercial 395 nm UV chip, and fix it with hot melt adhesive after connecting to the circuit to obtain the CA-G-PQDs film green conversion LED device.

[0051] The preparation method of the CA-R-PQDs film red conversion LED device includes the following steps:

[0052] Y1.CsPbBr 1.5 Cl 1.5 Synthesis of precursor solution: Dissolve 0.1 mmol CsBr, 0.1 mmol PbBr2, 0.1 mmol CsCl and 0.1 mmol PbCl2 according to the ratio in 5 mL DMF, stir at a speed of 600 rpm at room temperature for 3 hours, and finally seal it with sealant for later use;

[0053] Y2.CA solution preparation: Dissolve cellulose acetate powder in DMF and seal it for later use;

[0054] Y3.CA-R-PQDs film preparation: Add 2.5 mL of the precursor solution in step Y1 to 10 mL of the CA solution in step Y2, stir magnetically at 600 rpm at room temperature for 3 hours, vacuum filter for 24 hours, and then dry in a vacuum drying oven at 45 °C under a vacuum of 0.1 atm for 24 hours to obtain the CA-R-PQDs film;

[0055] Y4. Encapsulate the CA-R-PQDs film with a thickness of 0.17 mm on a commercial 395 nm UV chip, and fix it with hot melt adhesive after connecting to the circuit to obtain the CA-R-PQDs film red conversion LED device.

[0056] The preparation method of the CA-B-PQDs film blue conversion LED device includes the following steps:

[0057] Synthesis of Z1. CsPbBrI₂ precursor solution: Dissolve 0.5 mmol of CsBr and 0.5 mmol of PbI₂ in 20 mL of DMF, stir at a speed of 600 rpm at room temperature for 3 hours, and finally seal it with a sealant for later use;

[0058] Preparation of Z2. CA solution: Dissolve cellulose acetate powder in DMF and seal for later use;

[0059] Preparation of Z3. CA-B-PQDs film: Add 2.5 mL of the precursor solution in step Z1 to 10 mL of the CA solution in step Z2, stir magnetically at 600 rpm at room temperature for 3 hours, vacuum filter for 24 hours, and then dry in a vacuum drying oven at 45 °C under a vacuum of 0.1 atm for 24 hours to obtain the CA-B-PQDs film;

[0060] Z4. Encapsulate the CA-B-PQDs film with a thickness of 0.17 mm on a commercial 395 nm UV chip, and fix it with hot melt adhesive after connecting to the circuit to obtain a CA-B-PQDs film blue conversion LED device.

[0061] The TEM image of the CA-G-PQDs film in the example is as Figure 1 shown. The inset is a statistical chart of the quantum dot size distribution under a 20 nm TEM image. It can be seen that the PQDs are evenly dispersed on the surface of CA. The average size of the generated quantum dots is statistically obtained as 5.7 nm, mainly concentrated in the range of 5 nm and 6.5 nm. The synthesized PQDs have a narrow size distribution and uniform size. (c) shows the structure and lattice spacing of a single PQDs as 0.205 nm, corresponding to the (200) plane, which is consistent with the lattice parameters of CsPbBr₃ PQDs reported previously.

[0062] The TEM images of the CA-R-PQDs film and CA-B-PQDs film in this example are as Figure 2 shown. (a), (c), and (e) are the photos of CA-R-PQDs at 100 nm, 20 nm, and 5 nm respectively, and the inset is the size distribution diagram of CA-R-PQDs; (b), (d), and (f) are the photos of CA-B-PQDs at 50 nm, 20 nm, and 5 nm respectively, and the inset is the size distribution diagram of CA-B-PQDs. It can be seen that the average particle size of CA-R-PQDs and CA-B-PQDs are 8.56 ± 1.57 nm and 4.05 ± 0.77 nm respectively, which are close to the size distribution reported in the literature. And the quantum dots with different emissions can be evenly distributed on the CA film, and the crystal plane spacings of CA-R-PQDs and CA-B-PQDs can also be clearly observed as 0.26 nm and 0.24 nm respectively, which are consistent with the previously reported lattice spacing data.

[0063] In this example, the X-ray diffraction spectrum of the CA-G-PQDs film is as follows Figure 3 shown. The left inset is a photo under 365 nm ultraviolet light excitation, and the right is its high-resolution TEM photo. It can be seen that the quantum dot liquid in the cuvette emits bright green light. This strong luminescence performance proves the successful preparation of PQDs. The characteristic peaks 15.21°, 21.50°, 30.70°, 34.20°, 37.60°, and 43.69° in the XRD pattern correspond to the (100), (110), (200), (210), (211), and (202) crystal planes of the perovskite structure cubic crystal image, corresponding to the pdf card of cesium lead bromide perovskite. The TEM photo on the right further confirms the formation of CsPbBr3 PQDs.

[0064] In this example, the X-ray diffraction spectra of the CA-R-PQDs film, the CA-B-PQDs film, and the CA film are as follows Figure 4 shown. It can be seen that the peak positions in the CA-R-PQDs spectrum at 14.99°, 21.35°, and 30.24° correspond to the (100), (110), and (200) crystal planes. The CA-B-PQDs spectrum shows peak positions at 15.50°, 21.92°, and 31.34°, corresponding to the (100), (110), and (002) crystal planes, as well as the (211) crystal plane at 38.44°. The corresponding crystal plane indices on the standard PDF card (PDF#18-0364) belong to the cubic phase lattice.

[0065] In this example, the PL spectra of the CA-G-PQDs film, the CA-R-PQDs film, and the CA-B-PQDs film are as follows Figure 5 shown. The inset is a photo of ambient light and ultraviolet excitation (scale bar is 2 cm). It can be seen that the PL emission peaks of the CA-R-PQDs film, the CA-G-PQDs film, and the CA-B-PQDs film are 651.6 nm (red light), 525.4 nm (green light), and 463 nm (blue light) respectively. The relatively narrow FWHM indicates the purity of the color, and the pictures under 360 nm ultraviolet light excitation intuitively reflect this luminescence characteristic.

[0066] In this example, the average carrier lifetimes of the CA-G-PQDs film, the CA-R-PQDs film, and the CA-B-PQDs film are fitted using the TRPL decay exponential function, and they are CA-G-PQDs (τ ave = 16.895 ns), CA-R-PQDs (τ ave = 4.439 ns), and CA-B-PQDs (τ ave= 3.480 ns), which is better than the carrier lifetime (τ ave = 3.37 ns) of CNCs@PeNFs prepared using the biomass material cellulose nanocrystals reported in other literature. According to the Arrhenius relation, the relationship between the PL intensity and temperature was fitted, and the exciton binding energy (E b = 80.74 meV) of CA-G-PQDs, the exciton binding energy (E b = 68.39 meV) of CA-R-PQDs, and the exciton binding energy (E b = 205. meV) of CA-B-PQDs were calculated. All of them have relatively high exciton binding energies, providing good stability.

[0067] The simple monochromatic conversion LED device prepared in this example is as Figure 6 shown. Under a driving current of 20 mA, the light output photos of the three monochromatic conversion LED devices after 0 hours, 100 hours, and 200 hours are as Figure 7 shown. It can be seen that under the protection of CA, such monochromatic conversion devices can maintain long-term working stability. In particular, the brightness and luminescence purity of CA-G-PQDs-LED decay slowly after 200 hours of operation. The electroluminescence intensity decay of CA-R-PQDs-LED, CA-G-PQDs-LED, and CA-B-PQDs-LED at different operating times is as Figure 8 shown. It can be seen that with the change of time, the EL intensities of the three gradually decrease, but the decay rates are different. Among them, CA-G-PQDs-LED maintains 84.8% of the initial EL intensity after 200 h, and CA-R-PQDs-LED and CA-B-PQDs-LED also have 76.6% and 73.1% of the initial intensity.

[0068] The EL spectra (a) and their color gamut coordinates (with NTSC as the standard color gamut coordinates) (b) of the CA-R-PQDs-LED, CA-G-PQDs-LED, and CA-B-PQDs-LED devices in this example are as Figure 9As shown, it can be seen that the full width at half maximum (FWHM) of CA-R-PQDs-LED, CA-G-PQDs-LED, and CA-B-PQDs-LED are 31.0 nm, 21.8 nm, and 24.9 nm respectively. The relatively narrow FWHM proves that such color conversion display devices have good monochromaticity and color purity. The emission peak positions of CA-R-PQDs-LED, CA-G-PQDs-LED, and CA-B-PQDs-LED range from 464.6 nm (blue), 516.4 nm (green) to 678.2 nm (red). The wider spectral range is beneficial to the requirements of full-color display. Moreover, the CIE 1931 chromaticity diagrams of CA-R-PQDs-LED, CA-G-PQDs-LED, and CA-B-PQDs-LED are used to evaluate the color performance and color gamut coverage ability of the devices. The color gamut coverage reaches 132.3% of the NTSC standard, which is higher than the color gamut coverage ability of the color conversion devices prepared from current biomass and silica encapsulation materials. The color rendering indices (CRI) of CA-R-PQDs, CA-G-PQDs, and CA-B-PQDs measured are 23.8, 46.6, and 38.5 respectively, and they have considerable luminous efficiencies of 28.78 lm / W, 48.41 lm / W, and 12.78 lm / W. The above device parameters prove that the CA-based PQDs single-color conversion display devices have development potential in a relatively wide range of application scenarios.

[0069] The above has specifically described the preferred embodiments of the present invention. However, the present invention is not limited to the described embodiments. Those skilled in the art can make various equivalent deformations or substitutions without departing from the spirit of the present invention, and these equivalent deformations or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A full-color conversion LED device based on high-stability cellulose acetate perovskite quantum dots, characterized in that: The full-color conversion LED device includes a CA-G-PQDs film green conversion LED device, a CA-R-PQDs film red conversion LED device and a CA-B-PQDs film blue conversion LED device.

2. According to claim 1, a full-color conversion LED device based on high-stability cellulose acetate perovskite quantum dots is characterized in that: The method for preparing the CA-G-PQDs film green conversion LED device comprises the following steps: X1. Synthesis of CsPbBr3 precursor solution: Dissolve CsBr and PbBr2 in DMF, stir magnetically at room temperature until the solution is completely transparent, and seal for later use; X2. Preparation of CA solution: dissolve cellulose acetate powder in DMF and seal for later use; X3. Preparation of CA-G-PQDs film: Add the precursor solution in step X1 to the CA solution in step X2, stir magnetically at room temperature, vacuum filter and then vacuum dry to obtain a CA-G-PQDs film; X4. Encapsulate a CA-G-PQDs film with a thickness of 0.15mm-0.19mm on a commercial 395nm UV chip, connect it to the circuit, and fix it with hot melt adhesive to obtain a CA-G-PQDs film green conversion LED device.

3. According to claim 1, a full-color conversion LED device based on high-stability cellulose acetate perovskite quantum dots is characterized in that: The method for preparing the CA-R-PQDs film red conversion LED device comprises the following steps: Y1.CsPbBr 1.5 Cl 1.5 Synthesis of precursor solution: CsBr, PbBr2, CsCl and PbCl2 were dissolved in DMF, magnetically stirred at room temperature until the solution was completely transparent, and sealed for later use; Preparation of Y2.CA solution: dissolve cellulose acetate powder in DMF and seal for later use; Y3. Preparation of CA-R-PQDs film: adding the precursor solution in step Y1 to the CA solution in step Y2, magnetically stirring at room temperature, vacuum filtering and vacuum drying to obtain a CA-R-PQDs film; Y4. Encapsulate a CA-R-PQDs film with a thickness of 0.15mm-0.19mm on a commercial 395nm UV chip, connect it to the circuit, and fix it with hot melt adhesive to obtain a CA-R-PQDs film red conversion LED device.

4. According to claim 1, a full-color conversion LED device based on high-stability cellulose acetate perovskite quantum dots is characterized in that: The preparation method of the CA-B-PQDs film blue conversion LED device comprises the following steps: Z1. Synthesis of CsPbBrI2 precursor solution: Dissolve CsBr and PbI2 in DMF, stir magnetically at room temperature until the solution is completely transparent, and seal for later use; Preparation of Z2.CA solution: dissolve cellulose acetate powder in DMF and seal for later use; Z3. Preparation of CA-B-PQDs film: Add the precursor solution in step Z1 to the CA solution in step Z2, stir magnetically at room temperature, vacuum filter and then vacuum dry to obtain a CA-B-PQDs film; Z4. Encapsulate a CA-B-PQDs film with a thickness of 0.15mm-0.19mm on a commercial 395nm UV chip, connect it to the circuit, and fix it with hot melt adhesive to obtain a CA-B-PQDs film blue conversion LED device.

5. According to claim 2, a full-color conversion LED device based on high-stability cellulose acetate perovskite quantum dots is characterized in that: The molar ratio of CsBr to PbBr2 in step X1 is 1:1, and the solid-liquid ratio of the CsPbBr3 precursor solution is 14-15 g / L.

6. A full-color conversion LED device based on high-stability cellulose acetate perovskite quantum dots according to claim 3, characterized in that: The molar ratio of CsBr, PbBr2, CsCl and PbCl2 in step Y1 is 1:1:1:

1. 1.5 Cl 1.5 The solid-liquid ratio of the precursor solution is 20-21 g / L.

7. A full-color conversion LED device based on high-stability cellulose acetate perovskite quantum dots according to claim 4, characterized in that: The molar ratio of CsBr and PbI2 in step Z1 is 1:1, and the solid-liquid ratio of the CsPbBrI2 precursor solution is 16-17 g / L.

8. A full-color conversion LED device based on high-stability cellulose acetate perovskite quantum dots according to claim 2, 3 or 4, characterized in that: The concentration of the CA solution in step X2, step Y2 and step Z2 is 2 wt %.

9. A full-color conversion LED device based on high-stability cellulose acetate perovskite quantum dots according to claim 2, 3 or 4, characterized in that: The rotation speed of the magnetic stirring is 600 rpm, and the time of the magnetic stirring is 3 h.

10. A full-color conversion LED device based on high-stability cellulose acetate perovskite quantum dots according to claim 2, 3 or 4, characterized in that: The vacuum filtration time is 24 hours; the vacuum drying is drying at 45° C. for 24 hours under a vacuum degree of 0.1 atmosphere.

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