Perovskite quantum dots based on halogen component regulation and preparation method and application thereof, perovskite solar cell and optoelectronic device

Abstract

This invention provides a perovskite quantum dot based on halogen composition regulation, its preparation method and applications, perovskite solar cells and optoelectronic devices, belonging to the technical field of perovskite optoelectronic functional materials and devices. This invention constructs β-CsPbI 3‑x‑y Br x Cl y The halogen-controlled system, by precisely adjusting the type and ratio of halogen doping, achieves continuous and controllable adjustment of lattice parameters, band structure, and exciton recombination dynamics while maintaining the stability of the β-phase all-inorganic framework. The prepared perovskite quantum dots can fully leverage their low trapped state density, and combined with improved lattice stability, enhance the conversion efficiency and operational stability of solar cells.

Description

Technical Field

[0001] This invention relates to the field of perovskite optoelectronic functional materials and devices, and particularly to a perovskite quantum dot based on halogen composition regulation, its preparation method and application, perovskite solar cells and optoelectronic devices. Background Technology

[0002] All-inorganic halide perovskite nanocrystals (CsPbX3, X = Cl, Br, I) possess high photoluminescence quantum efficiency, narrow emission lines, tunable band gaps, and excellent charge carrier transport properties, showing broad application potential in fields such as light-emitting displays, photovoltaic power generation, and radiation detection. Among them, CsPbI3 covers the red to near-infrared wavelength range and is a key material system with both light emission and light absorption functions. One of the black phases of CsPbI3 is β-CsPbI3, which has a tetragonal crystal structure. Compared with the ideal cubic α phase, the Pb-I-Pb bond angle is reduced from 180° to about 164°, forming a slightly distorted PbI6 octahedral framework. Theoretical and experimental results show that the β phase has relatively high structural stability and good charge transport properties, making it a preferred crystal phase for constructing stable optoelectronic devices.

[0003] In perovskite solar cells, the crystal phase stability and defect density of the light-absorbing layer directly determine the device's efficiency and lifetime. The all-inorganic CsPbI3 system has inherent advantages in heat resistance and moisture resistance, but its black phase is prone to transforming into the yellow delta phase, and it is accompanied by deep-level defects such as high iodine vacancies, making it difficult for all-inorganic solar cells based on CsPbI3 to simultaneously achieve high efficiency and long-term stability. Summary of the Invention

[0004] The purpose of this invention is to provide a perovskite quantum dot based on halogen composition regulation, its preparation method and applications, perovskite solar cells and optoelectronic devices, and to stabilize β-CsPbI under mild preparation conditions through reasonable lattice regulation of halogen composition and a defect synergistic passivation strategy. 3-x-y Br x Cl y Black phase, while obtaining perovskite quantum dots with excellent light-emitting properties, can also construct all-inorganic perovskite solar cells with both high efficiency and high stability.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing perovskite quantum dots based on halogen composition regulation, comprising the following steps: Lead iodide, hydroiodic acid, and N,N-dimethylformamide were mixed and subjected to a precipitation reaction to obtain DMAPbI3; The DMAPbI3, CsI, halogen source solvent, and methyl α-bromophenylacetate were mixed to obtain a precursor solution; the halogen source solvent contained Br and / or Cl. In a room temperature and air environment, the precursor solution and antisolvent are mixed and subjected to a redeposition reaction. The resulting precipitate is then redispersed to obtain perovskite quantum dots based on halogen component regulation.

[0006] Preferably, the ratio of lead iodide to hydroiodic acid is 10 mmol: 3~5 mL; and the volume ratio of N,N-dimethylformamide to hydroiodic acid is 10: 3~5.

[0007] Preferably, the molar ratio of CsI to DMAPbI3 is 2:1 to 1:2.

[0008] Preferably, the organic solvent includes one or more of N,N-dimethylacetamide, N,N-dimethylformamide, and dimethyl sulfoxide; The halogen source solvent is a mixture of a halogen source and an organic solvent; the volume ratio of the halogen source solvent to methyl α-bromophenylacetate is 2:1 to 8:1. The halogen source includes a first halogen source, a second halogen source, or a third halogen source; The first halogen source is CsBr and PbBr2; the ratio of CsBr and PbBr2 to the organic solvent is 0.4 mmol: 0.4~0.8 mmol: 10~20 mL; The second halogen source is CsCl and PbCl2; the ratio of CsCl and PbCl2 to the organic solvent is 0.4 mmol: 0.4~0.8 mmol: 10~20 mL; The third halogen source is CsBr, CsCl and PbBr2; the ratio of CsBr, CsCl and PbBr2 to organic solvent is 0.3mmol:0.1mmol:0.4~0.8mmol:10~20mL; The ratio of CsI to the total amount of halogen source solvent and methyl α-bromophenylacetate is 0.2~1 mmol: 0.5~1 mL; The solvent used for redispersion is toluene.

[0009] Preferably, the antisolvent includes isopropanol; the volume ratio of the precursor solution to the antisolvent is 1:40 to 1:70. The reprecipitation reaction was carried out at room temperature for 5-15 minutes. The solvent used for redispersion is toluene.

[0010] This invention provides perovskite quantum dots prepared by the method described above, based on halogen composition regulation, with a chemical composition of β-CsPbI. 3-x-y Br x Cl y , where 0≤x<3, 0≤y<3, x+y<3, and x and y are not both 0.

[0011] This invention provides the application of perovskite quantum dots based on halogen composition regulation in the field of perovskite solar cells as described in the above technical solution.

[0012] This invention provides a perovskite solar cell, comprising a transparent conductive substrate, an electron transport layer, an absorber layer, a hole transport layer, and a metal electrode stacked sequentially. The absorber layer is prepared from perovskite quantum dots based on halogen composition control as described in the above technical solution.

[0013] The present invention provides an optoelectronic device, including the perovskite solar cell described in the above technical solution and a light conversion film covering the surface of the perovskite solar cell.

[0014] Preferably, the optoelectronic device includes a light-emitting device, a display device, or a battery device.

[0015] This invention provides a method for preparing perovskite quantum dots based on halogen component regulation. The chemical composition of the prepared perovskite quantum dots is: β-CsPbI 3-x-y Br x Cl y This invention introduces Br into the β-CsPbI3 lattice. - and / or C - Partially replaces I - This allows for the coordinated control of the perovskite lattice structure and band structure at specific sites. While maintaining the stability of the β-phase all-inorganic framework structure, the control of Br... - and / or Cl - The doping ratio can be adjusted to continuously control lattice parameters, band structure, and exciton recombination dynamics. Its core mechanism lies in: utilizing Br... - With Cl - Compared to I - It has a smaller ionic radius and is partially substituted with I - Anisotropic lattice compression effects are generated after the lattice sites, thereby modulating the Goldschmidt tolerance factor of the perovskite structure. This structural modulation can stabilize the β-phase lattice structure at the microscale, effectively suppress the spontaneous phase transition from the β-phase to the non-luminescent δ-phase (yellow phase), and improve the structural stability of quantum dots.

[0016] This invention, through the aforementioned halogen component modulation strategy, enables the production of structurally stable β-phase perovskite quantum dot materials over a wide temperature range, and achieves continuous tunability of the emission wavelength in the visible light region. The resulting quantum dots exhibit low defect state density, high luminescence purity, and excellent structural stability.

[0017] Compared with the prior art, the present invention has the following beneficial effects: (1) The process is simple, the conditions are mild, and the environment is friendly. This invention uses DMAPbI3 precursor in combination with an organic solvent system to achieve β-CsPbI3 at room temperature and under atmospheric conditions. 3-x-y Br x Cl y The preparation of quantum dots eliminates the dependence on high-temperature oil baths and inert atmospheres in traditional hot injection processes. The operation steps are simplified, and the reaction conditions are easy to control and scale up, showing good potential for large-scale preparation.

[0018] Compared with traditional synthesis systems using PbI2 as the lead source, the use of DMAPbI3 as the lead halide precursor in this invention has significant advantages. DMAPbI3, as an organic-inorganic hybrid lead halide intermediate, contains Pb in its structure. 2+ Centered on, I - The coordination units formed by coordination are more likely to undergo structural recombination in solution and transform into the target β-CsPbI. 3-x-y Br x Cl y The perovskite structure lowers the energy barrier for crystal nucleation and growth, allowing the reaction to proceed under mild conditions. In contrast, the PbI2 system requires a dissolution-coordination-reconstruction process, making the nucleation pathway more complex.

[0019] Meanwhile, DMA solvent possesses moderate coordination ability and high chemical stability, effectively dissolving precursors and maintaining system stability without forming excessively strong coordination structures that could inhibit crystal nucleation, thus facilitating rapid precursor conversion and uniform nucleation. Furthermore, DMA exhibits good stability in air, avoiding the decomposition reactions that may occur with DMF or DMSO under water and oxygen conditions, thereby improving the environmental adaptability and repeatability of the process.

[0020] In summary, this invention reduces the requirements for reaction conditions while achieving effective control over the nucleation process, significantly improving the nucleation uniformity and structural stability of quantum dots. It also has the advantages of simple process and strong scalability, and has high industrial application value.

[0021] (2) This invention can regulate Br - With Cl - The doping ratio was adjusted to achieve the desired doping ratio for β-CsPbI 3-x-y Br x Cly The "multi-scale structure locking" of the phase structure weakens the phase transition trend from black phase to yellow phase, while effectively reducing deep-level defects such as iodine vacancies and suppressing non-radiative recombination channels, which is beneficial to improving the optical performance and environmental stability of the material. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the preparation process of DMAPbI3 in this invention; Figure 2 This is a schematic diagram illustrating the preparation of perovskite quantum dots based on halogen component regulation according to the present invention. Figure 3 The X-ray diffraction pattern of DMAPbI3 in the preparation example; Figure 4 Scanning electron microscope image of DMAPbI3 in the preparation example; Figure 5 For (a) β-CsPbI3 and (b) β-CsPbI in Examples 1-3 1.5 Br 1.5 (c)β-CsPbIBr 1.7 Cl 0.3 Transmission electron microscopy and high-resolution transmission electron microscopy images, as well as (d)β-CsPbI3 and (e)β-CsPbI 1.5 Br 1.5 (f)β-CsPbIBr 1.7 Cl 0.3 Size distribution histogram; Figure 6 The β-CsPbI3 and β-CsPbI in Examples 1-3 1.5 Br 1.5 With β-CsPbIBr 1.7 Cl 0.3 X-ray diffraction pattern of quantum dots; Figure 7 The β-CsPbI3 and β-CsPbI in Examples 1-3 1.5 Br 1.5 With β-CsPbIBr 1.7 Cl 0.3 Emission spectrum of quantum dots; Figure 8 The β-CsPbI3 and β-CsPbI in Examples 1-3 1.5 Br 1.5 With β-CsPbIBr 1.7 Cl 0.3 Emission and absorption spectra of quantum dots (a~c) and Urbach energy calculations (d~f); Figure 9The β-CsPbI3 and β-CsPbI in Examples 1-3 1.5 Br 1.5 With β-CsPbIBr 1.7 Cl 0.3 The decay curve of quantum dots; Figure 10 This is a schematic diagram of the perovskite solar cell device structure in Application Example 1; Figure 11 The bare battery in Application Example 1 and the battery with Ba in Application Example 2 0.7 Mg 0.7 Al 9.97 O 17 0.3Eu 2+ 0.3Mn 2+ 0.03Cr 3+ Comparison of IV curves for perovskite solar cells with light-conversion films. Detailed Implementation

[0023] In this invention, unless otherwise specified, the raw materials or reagents required for preparation are all commercially available products well known to those skilled in the art.

[0024] like Figures 1-2 As shown, this invention provides a method for preparing perovskite quantum dots based on halogen composition regulation, comprising the following steps: Lead iodide, hydroiodic acid, and N,N-dimethylformamide were mixed and subjected to a precipitation reaction to obtain DMAPbI3; The DMAPbI3, CsI, halogen source solvent, and methyl α-bromophenylacetate were mixed to obtain a precursor solution; the halogen source solvent contained Br and / or Cl. In a room temperature and air environment, the precursor solution and antisolvent are mixed and subjected to a redeposition reaction. The resulting precipitate is then redispersed to obtain perovskite quantum dots based on halogen component regulation.

[0025] In this invention, hydroiodic acid is preferably mixed with N,N-dimethylformamide (DMF), and lead iodide (PbI2) is dissolved in the resulting mixture. The mixture is stirred at room temperature to carry out a precipitation reaction until it becomes clear.

[0026] In this invention, the preferred ratio of lead iodide to hydroiodic acid is 10 mmol:3~5 mL, more preferably 10 mmol:3~4 mL; the preferred volume ratio of N,N-dimethylformamide to hydroiodic acid is 10:3~5, more preferably 10:3~4.

[0027] After the precipitation reaction is complete, the present invention preferably adds anhydrous ethanol to the obtained product until a yellow precipitate is induced to form. After washing, centrifugation and drying, DMAPbI3 is obtained. The solvent used for washing is preferably cyclohexane, and the drying is preferably carried out under vacuum at 50-80 °C for 10-20 h, more preferably under vacuum at 60 °C for 16 h.

[0028] In this invention, the molar ratio of CsI to DMAPbI3 is preferably 2:1 to 1:2, and more preferably 1:2.

[0029] In this invention, the halogen source solvent is preferably a mixture of a halogen source and an organic solvent.

[0030] In this invention, the halogen source preferably includes a first halogen source, a second halogen source, or a third halogen source; The first halogen source is preferably CsBr and PbBr2; the ratio of CsBr and PbBr2 to organic solvent is preferably 0.4 mmol:0.4~0.8 mmol:10~20 mL, more preferably 0.4 mmol:0.4 mmol:10 mL; The second halogen source is preferably CsCl or PbCl2; the ratio of CsCl, PbCl2 to organic solvent is preferably 0.4 mmol: 0.4~0.8 mmol: 10~20 mL, more preferably 0.4 mmol: 0.4 mmol: 10 mL; The third halogen source is preferably CsBr, CsCl, and PbBr2; the ratio of CsBr, CsCl, and PbBr2 to the organic solvent is preferably 0.3mmol:0.1mmol:0.4~0.8mmol:10~20mL, more preferably 0.3mmol:0.1mmol:0.4mmol:10mL.

[0031] In this invention, the organic solvent preferably includes one or more of N,N-dimethylacetamide (DMA), N,N-dimethylformamide, and dimethyl sulfoxide; when the organic solvent is two or more of the above, this invention does not have a special limitation on the ratio of different types of organic solvents, and any ratio is acceptable.

[0032] In this invention, the volume ratio of the halogen source solvent to methyl α-bromophenylacetate is preferably 2:1 to 8:1, more preferably 3:1 to 6:1, and even more preferably 5:1.

[0033] In this invention, the preferred ratio of CsI to the total amount of halogen source solvent and methyl α-bromophenylacetate is 0.2~1mmol:0.5~1mL, more preferably 0.2~0.5mmol:0.5mL.

[0034] In this invention, the antisolvent preferably comprises isopropanol; the volume ratio of the precursor solution to the antisolvent is preferably 1:40 to 1:70, more preferably 1:50 to 1:60. This invention utilizes the antisolvent to trigger nucleation.

[0035] In this invention, the temperature of the reprecipitation reaction is preferably room temperature, and the time is preferably 5 to 15 min, more preferably 10 min.

[0036] After the redeposition reaction is completed, the product is preferably centrifuged at 10,000 rpm for 3 min, the supernatant is discarded, and the precipitate is redispersed to obtain perovskite quantum dots based on halogen component regulation. The solvent used for redispersion is preferably toluene. The amount of toluene used is not particularly limited in this invention, and the dispersion can be adjusted according to the requirements.

[0037] This invention provides perovskite quantum dots prepared by the method described above, based on halogen composition regulation, with a chemical composition of β-CsPbI. 3-x-y Br x Cl y , where 0≤x<3, 0≤y<3, x+y<3, and x and y are not both 0.

[0038] In this invention, 0.5≤x≤2 is more preferred, 1.5≤x≤1.7 is even more preferred, 0.3≤y≤2 is even more preferred, and 0.5≤y≤1 is even more preferred.

[0039] In this invention, the chemical composition of the perovskite quantum dots based on halogen component regulation is preferably β-CsPbI. 1.5 Br 1.5 or β-CsPbIBr 1.7 Cl 0.3 .

[0040] This invention provides the application of perovskite quantum dots based on halogen composition regulation in the field of perovskite solar cells as described in the above technical solution.

[0041] This invention provides a perovskite solar cell, comprising a transparent conductive substrate, an electron transport layer, an absorber layer, a hole transport layer, and a metal electrode stacked sequentially. The absorber layer is prepared from perovskite quantum dots based on halogen composition control as described in the above technical solution.

[0042] In this invention, the electron transport layer material and thickness, the hole transport material type and doping method, and the metal electrode material can be adjusted as needed.

[0043] In embodiments of the present invention, the transparent conductive substrate is preferably FTO, the electron transport layer is preferably TiO2, the hole transport layer is preferably Spiro-OMeTAD (2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirodifluorene), the metal electrode is preferably Au, and the perovskite solar cell has a nip stacked structure.

[0044] In this invention, the thickness of the absorption layer is preferably 300~500 nm, more preferably 400 nm.

[0045] In this invention, the method for preparing the perovskite solar cell preferably includes the following steps: (1) FTO glass substrate treatment: Cut the FTO conductive glass into glass sheets of the required size, immerse them in a mixture of glass cleaning solution and ultrapure water for ultrasonic cleaning, rinse them clean and blow them dry, fix the FTO glass substrate in a petri dish to reserve the electrode area, and then perform ultraviolet-ozone treatment to remove surface organic contaminants and improve substrate wettability. (2) Electron transport layer coating and annealing: Prepare an electron transport layer precursor solution, coat it on the surface of FTO substrate to form an electron transport layer film, and dry or anneal it to make the electron transport layer uniform and dense. (3) Spin coating and annealing of perovskite absorber layer based on halogen composition control: spin coating a perovskite quantum dot precursor solution based on halogen composition control onto the surface of the electron transport layer to form a thin film, and then annealing to obtain a well-crystallized and dense absorber layer; the spin coating rate is preferably 1000 rpm / 10~15 s in the first stage and 3000 rpm / 30~40 s in the second stage, with 1 mL of antisolvent added at the 10th s of the second stage; the annealing method is preferably continuous annealing in two temperature zones, more preferably annealing at 130~160 ℃ for 2~5 min, and then annealing at 160~200 ℃ for 4~10 min.

[0046] (4) Spin coating of hole transport layer: spin coating hole transport material onto perovskite absorber layer, and then allowing it to stand or anneal to form a stable hole transport layer. (5) Metal electrode evaporation: Metal electrodes are deposited on the surface of the hole transport layer to form the top electrode, thus obtaining a perovskite solar cell.

[0047] This invention does not impose any special limitations on other parameters not mentioned in the preparation of the perovskite solar cell; it can be prepared according to parameters well known in the art.

[0048] The present invention provides an optoelectronic device, including the perovskite solar cell described in the above technical solution and a light conversion film covering the surface of the perovskite solar cell.

[0049] In this invention, the phosphor used in the light conversion film is preferably Ba. 0.7 Mg 0.7 Al 9.97 O 17 0.3Eu 2+ 0.3Mn 2 + 0.03Cr 3+ The phosphor was obtained by referring to the prior art entitled "A red fluorescent material and its preparation method and application, energy down-conversion thin film and its preparation" (application number 202411035747.0, publication number CN118995206A).

[0050] In this invention, the preferred method for preparing the optoelectronic device is as follows: EVA and phosphor are mixed at a mass ratio of 10-20:1 (more preferably 15:1), and toluene is added at a ratio of 1g:4mL for EVA and toluene solvent. The resulting mixture is then spin-coated onto the surface of a perovskite solar cell and dried to form a dense film. The spin-coating speed is preferably 1000-3000 rpm, more preferably 1500-2000 rpm.

[0051] In this invention, the optoelectronic device preferably includes a light-emitting device, a display device, or a battery device. This invention does not impose any particular limitation on the specific structure and type of the optoelectronic device; any of the aforementioned devices well-known in the art are acceptable.

[0052] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0053] Unless otherwise specified, the experimental methods described in the various embodiments of this invention are conventional methods; unless otherwise specified, the raw materials used are all commercially available products, and the proportions are all by mass percentage.

[0054] Preparation Example

[0055] like Figure 1 As shown, the preparation of DMAPbI3 was as follows: 10 mmol of PbI2 was added to a mixture of 3 mL of hydroiodic acid and 10 mL of N,N-dimethylformamide, and the mixture was magnetically stirred at room temperature until the solution became clear. Then anhydrous ethanol was added to induce the precipitation of a yellow precipitate. The precipitate was washed with anhydrous ethanol, centrifuged, and dried under vacuum at 60 °C for 16 h to obtain yellow DMAPbI3 powder.

[0056] Example 1

[0057] Preparation of β-CsPbI3 perovskite quantum dots: (1) Preparation of precursor solution: Weigh 0.2 mmol CsI and 0.4 mmol DMAPbI3, add them to 0.5 mL N,N-dimethylacetamide (DMA), and stir magnetically for 10 min at room temperature to obtain a clear yellow β-CsPbI3 precursor solution; (2) Synthesis of quantum dots: Under room temperature and air conditions, 0.4 mL of the above precursor solution was rapidly injected into 20 mL of isopropanol and reacted for 10 min. After centrifugation at 10000 rpm for 3 min, the supernatant was discarded. The precipitate was redispersed with 2 mL of toluene and centrifuged again. The supernatant was collected to obtain β-CsPbI3 quantum dot solution.

[0058] Example 2

[0059] β-CsPbI 1.5 Br 1.5 Preparation of perovskite quantum dots: (1) Preparation of Br source solvent: Weigh 0.4 mmol CsBr and 0.4 mmol PbBr2, dissolve them in 10 mL DMA, stir magnetically until completely clear, take 0.5 mL of the solution, add 0.1 mL methyl α-bromophenylacetate, mix well to obtain Br source solvent; (2) Preparation of precursor solution: Take 0.5 mL of the Br source solvent obtained in step (1), add it to 0.20 mmol CsI and 0.40 mmol DMAPbI3, stir at room temperature for 10 min to obtain β-CsPbI 1.5 Br 1.5 Precursor solution; (3) Synthesis of quantum dots: Under room temperature and air conditions, 0.4 mL of the above precursor solution was rapidly injected into 20 mL of isopropanol and reacted for 10 min. After centrifugation at 10000 rpm for 3 min, the supernatant was discarded, the precipitate was redispersed with 2 mL of toluene and centrifuged again. The supernatant was collected to obtain β-CsPbI 1.5 Br 1.5 Quantum dot solution.

[0060] Example 3

[0061] based on Figure 2 The experimental design employed a ligand-assisted reprecipitation method to introduce bromine (Br) and chloride (Cl) ions for synergistic doping, successfully synthesizing β-CsPbI. 3-x-y Br x Cl y All-inorganic perovskite quantum dots.

[0062] β-CsPbIBr1.7 Cl 0.3 Preparation of perovskite quantum dots: (1) Preparation of Br / Cl source mixed solvent: Weigh 0.3 mmol CsBr, 0.1 mmol CsCl and 0.4 mmol PbBr2, dissolve them in 10 mL DMA, stir until clear, take 0.5 mL of the solution and add 0.1 mL α-bromophenylacetic acid methyl ester, mix well to obtain Br / Cl source mixed solvent; (2) Preparation of precursor solution: Take 0.5 mL of the Br / Cl source mixed solvent obtained in step (1), add it to 0.20 mmol CsI and 0.40 mmol DMAPbI3, stir at room temperature for 10 min to obtain β-CsPbIBr 1.7 Cl 0.3 Precursor solution; (3) Quantum dot synthesis: Under room temperature and air conditions, 0.4 mL of the above precursor solution was rapidly injected into 20 mL of isopropanol and reacted for 10 min. After centrifugation at 10000 rpm for 3 min, the supernatant was discarded. The precipitate was redispersed with 2 mL of toluene and centrifuged again. The supernatant was collected to obtain β-CsPbIBr. 1.7 Cl 0.3 Quantum dot solution.

[0063] Application Example 1

[0064] β-CsPbIBr 1.7 Cl 0.3 Fabrication of perovskite solar cells: like Figure 10 As shown, the device structure is: FTO (600nm) / TiO2 (40nm) / β-CsPbIBr 1.7 Cl 0.3 Perovskite absorber layer (400nm) / spiro-OMeTAD (200nm) / gold electrode (80nm).

[0065] (1) FTO glass substrate treatment: Cut FTO conductive glass into small pieces of 2.5 cm × 2.5 cm, place them in a mixed solution of glass cleaning solution and ultrapure water with a volume ratio of 1:100, and ultrasonically clean for 30 min; rinse with ultrapure water 3 times, blow dry the surface moisture, fix the FTO glass in the petri dish with high temperature tape and reserve the electrode preparation area, and place it in the UV-ozone cleaner for 15 min to remove organic contaminants and improve surface wettability; (2) Preparation of electron transport layer film: Mix 180 mL of ultrapure water with 20 mL of electron transport layer concentrate (commercial TiO2 precursor) evenly, pour it into a culture dish with FTO substrate placed in it, so that the conductive surface of FTO is completely immersed; cover with plastic wrap and seal, transfer the culture dish to a 70 ℃ constant temperature drying oven for 60 min, take out the film and rinse with ultrapure water to remove unreacted precursor, and obtain FTO substrate covered with electron transport layer, which is then immersed in anhydrous ethanol for later use.

[0066] (3) Preparation of perovskite absorber layer film: Take out the FTO / TiO2 electron transport layer substrate obtained in step (2), blow the surface solvent with an air compressor, anneal at 200 °C for 30 min to remove adsorbed moisture; after cooling to room temperature, perform ozone cleaning for 15 min to improve surface cleanliness and wettability, and then transfer the substrate to a nitrogen glove box.

[0067] Take the β-CsPbIBr obtained in Example 3 1.7 Cl 0.3 70 μL of the precursor solution was dropped onto the electron transport layer surface and allowed to spread uniformly. A two-stage spin-coating process was then employed: the first stage involved spinning at 1000 rpm for 10 s, followed by a second stage at 3000 rpm for 40 s. At the 10th second of the second stage, 1 mL of isopropanol was added as an antisolvent to induce rapid crystallization. After spin-coating, the sample was annealed at 140℃ for 2 min and then at 180℃ for 4 min, with rapid temperature transitions to obtain dense and homogeneous β-CsPbIBr. 1.7 Cl 0.3 Perovskite absorber layer film.

[0068] (4) Preparation of hole transport layer film: After annealing and cooling, the perovskite film is transferred back into the nitrogen glove box. The pre-prepared and filtered hole transport material solution (Spiro-OMeTAD solution) is uniformly dropped onto the surface of the perovskite absorber layer and spin-coated at 5000 rpm for 30 s to form a uniform hole transport layer film. After spin-coating, the sample is placed in a desiccator and left to stand in the air overnight to allow the hole transport layer to be fully oxidized and doped.

[0069] (5) Fabrication of the gold electrode: Using a knife, a pre-existing FTO electrode area was made on the back of the device. The hole transport layer and perovskite layer on the corresponding area were scraped away to expose the FTO conductive glass for the lower electrode. The sample was then placed in a vacuum thermal evaporation apparatus, and an 80 nm thick gold electrode was deposited on the surface of the Spiro-OMeTAD hole transport layer to form the top electrode, thus obtaining a complete nip-type perovskite solar cell. The effective working area of ​​a single cell device is 0.09 cm². 2 .

[0070] Application Example 2

[0071] Load Ba 0.7 Mg 0.7 Al 9.97 O 17 0.3Eu 2+ 0.3Mn 2+ 0.03Cr 3+ β-CsPbIBr light conversion film based on halogen composition regulation 1.7 Cl 0.3 Fabrication and performance comparison of perovskite solar cells, including the phosphor Ba. 0.7 Mg 0.7 Al 9.97 O 17 0.3Eu 2+ 0.3Mn 2+ 0.03Cr 3+ Prepared according to the method of Example 1 in patent CN118995206A; In the β-CsPbIBr prepared in Application Example 1 1.7 Cl 0.3 Based on perovskite solar cells, further research is conducted on the fabrication of optoelectronic devices loaded with phosphor films to enhance light energy conversion.

[0072] 1) Preparation of light conversion film: Ethylene-vinyl acetate copolymer (EVA) and phosphor Ba 0.7 Mg 0.7 Al 9.97 O 17 0.3Eu 2+ 0.3Mn 2+ 0.03Cr 3+ Mix at a mass ratio of 15:1, and simultaneously add EVA and toluene solvent at a ratio of 1 g: 4 mL. Place the resulting mixture in a vacuum degassing machine, evacuate and stir for 5 min to obtain a uniform light conversion adhesive powder mixture. 2) Coating of light conversion film: The obtained adhesive powder mixture was uniformly spin-coated onto the surface of the perovskite solar cell prepared in Example 1 at a speed of 1500 rpm / s at room temperature. After spin-coating, the device was placed in an oven to dry, so that the light conversion film and the perovskite absorption layer formed a dense bond.

[0073] Characterization and performance testing

[0074] Figure 3 The X-ray diffraction pattern of DMAPbI3 in the preparation example demonstrates the successful preparation of DMAPbI3.

[0075] Figure 4 The image shows a scanning electron microscope image of DMAPbI3 from the preparation example, revealing its rod-like structure.

[0076] Figure 5 For (a) β-CsPbI3 and (b) β-CsPbI in Examples 1-3 1.5 Br 1.5 (c)β-CsPbIBr 1.7 Cl 0.3 Transmission electron microscopy and high-resolution transmission electron microscopy images, as well as (d)β-CsPbI3 and (e)β-CsPbI 1.5 Br 1.5 (f)β-CsPbIBr 1.7 Cl 0.3 Size distribution histogram; based on Figure 5 It can be observed that with further halogen incorporation, the quantum dots gradually transform from irregular shapes into highly uniform cubic structures, with their average particle size decreasing from 11.69 nm for β-CsPbI3 to β-CsPbI3. 1.5 Br 1.5 The 9.88 nm value was further optimized to β-CsPbIBr. 1.7 Cl 0.3 The particle size is 9.77 nm. This morphological evolution pattern indicates that the introduction of multi-component halogens effectively inhibits excessive crystal growth and improves particle size uniformity by adjusting the nucleation energy barrier.

[0077] Figure 6 The β-CsPbI3 and β-CsPbI in Examples 1-3 1.5 Br 1.5 With β-CsPbIBr 1.7 Cl 0.3 X-ray diffraction pattern of quantum dots; Figure 6 The XRD diffraction patterns reveal the intrinsic mechanism of its structural stability: due to I - (2.20 Å), Br - (1.96 Å) and Cl - The ionic radius of (1.81 Å) decreases sequentially, and when the smaller the radius of Br... - and Cl - I in the lattice - At this time, the interplanar spacing decreases accordingly, causing the diffraction peaks to shift towards higher angles. This lattice contraction enhances the binding energy of the Pb-X bonds, thus macroscopically enhancing the stability of the β-phase structure, enabling it to effectively resist the spontaneous transformation to the non-luminescent yellow phase at room temperature.

[0078] Figure 7 The β-CsPbI3 and β-CsPbI in Examples 1-3 1.5 Br 1.5With β-CsPbIBr 1.7 Cl 0.3 The emission spectra of quantum dots (under the same test conditions) reflect the change in halogen composition from β-CsPbI3 to β-CsPbI 1.5 Br 1.5 Then to β-CsPbIBr 1.7 Cl 0.3 The emission peaks show a gradual change, with a significant blue shift, indicating a gradual increase in the band gap. Simultaneously, the peak shape narrows while the intensity increases, suggesting improved crystal quality and radiative recombination efficiency after alloying. Specifically, β-CsPbI3 emission occurs in the long-wavelength region with a broad peak, indicating strong defects or structural disorder. The introduction of Br results in a significant blue shift and increased intensity of the peak. Further Cl doping leads to a continued blue shift and sharpening of the emission, indicating enhanced lattice rigidity and suppressed nonradiative recombination. This trend is consistent with the lattice contraction and electronic structure modulation caused by halogen substitution.

[0079] Figure 8 The β-CsPbI3 and β-CsPbI in Examples 1-3 1.5 Br 1.5 With β-CsPbIBr 1.7 Cl 0.3 Emission and absorption spectra of quantum dots (a~c) and Urbach energy calculations (d~f); among them, Figure 8 (a~c) spectral analysis shows that with increasing doping degree, the exciton absorption peak and PL emission peak exhibit a significant blue shift trend, and the Stokes shift decreases from approximately 78.83 meV for β-CsPbI3 to β-CsPbI3. 1.5 Br 1.5 The value was 69.60 meV, and further decreased to β-CsPbIBr. 1.7 Cl 0.3 The value of 62.20 meV indicates a decrease in lattice relaxation and a reduction in defect states. Figure 8 The logarithmic absorption coefficient (d~f) extracted from the optical absorption spectrum is used as a function of photon energy, along with β-CsPbI3 and β-CsPbI... 1.5 Br 1.5 β-CsPbIBr 1.7 Cl 0.3 The corresponding Urbach energy of QDs decreased from 54.57 meV to 42.11 meV, and further to 23.35 meV. This decrease quantitatively demonstrates that co-doping effectively reduces the structural disorder within the material, thus demonstrating a reduction in the density of local states.

[0080] Figure 9 The β-CsPbI3 and β-CsPbI in Examples 1-31.5 Br 1.5 With β-CsPbIBr 1.7 Cl 0.3 Decay curves of quantum dots. Based on Figure 9 The obtained data is shown in Table 1.

[0081] The suppression of microscopic defects is directly reflected in the changes in carrier dynamic parameters, according to Table 1 and... Figure 9 Fluorescence decay kinetics analysis showed that, through Br / Cl co-doping, the photoluminescence quantum yield (PLQY) of quantum dots increased from 47% to 73% and 93%. Specifically, the short-lived component τ1, possibly related to the trapping process of surface defect states, increased from 4.23 ns to 21.15 ns, while the long-lived component τ2, reflecting intrinsic radiative recombination, extended from 28.41 ns to 131.26 ns. Ultimately, this resulted in an increase in the average fluorescence lifetime τavg from 25.52 ns to 99.93 ns, demonstrating effective passivation of non-radiative recombination centers caused by iodine vacancies and improved carrier radiative recombination efficiency.

[0082] Table 1 lists the β-CsPbI3 and β-CsPbI3 in Examples 1-3. 1.5 Br 1.5 With β-CsPbIBr 1.7 Cl 0.3 The double exponential fitting parameters of the decay curve and lifetime

[0083] Figure 10 To apply the perovskite solar cell structure in Example 1, Figure 11 The bare battery in Application Example 1 and the battery with Ba in Application Example 2 0.7 Mg 0.7 Al 9.97 O 17 0.3Eu 2+ 0.3Mn 2+ 0.03Cr 3+ Comparison of IV curves for perovskite solar cells with light-conversion films; Figure 11 The results show that, compared to bare perovskite solar cells (with a baseline efficiency PCE of 7.35%), BaMgAl loaded with BaMgAl… 10 O 17 30%Eu 2+ 30%Mn 2+ 3%Cr 3+ After the light conversion film was applied, the PCE increased to 7.51% (a relative improvement of 2.18%). From lattice manipulation, kinetic optimization to device integration, this invention demonstrates the scientific validity and feasibility of synergistically improving the performance of perovskite devices through compositional manipulation and light conversion technology.

[0084] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing perovskite quantum dots based on halogen composition regulation, characterized in that, Includes the following steps: Lead iodide, hydroiodic acid, and N,N-dimethylformamide were mixed and subjected to a precipitation reaction to obtain DMAPbI3; The DMAPbI3, CsI, halogen source solvent, and methyl α-bromophenylacetate were mixed to obtain a precursor solution; the halogen source solvent contained Br and / or Cl. In a room temperature and air environment, the precursor solution and antisolvent are mixed and subjected to a redeposition reaction. The resulting precipitate is then redispersed to obtain perovskite quantum dots based on halogen component regulation.

2. The preparation method according to claim 1, characterized in that, The ratio of lead iodide to hydroiodic acid is 10 mmol: 3~5 mL; the volume ratio of N,N-dimethylformamide to hydroiodic acid is 10: 3~5.

3. The preparation method according to claim 1, characterized in that, The molar ratio of CsI to DMAPbI3 is 2:1 to 1:

2.

4. The preparation method according to claim 1, characterized in that, The halogen source solvent is a mixture of a halogen source and an organic solvent; The halogen source includes a first halogen source, a second halogen source, or a third halogen source; the organic solvent includes one or more of N,N-dimethylacetamide, N,N-dimethylformamide, and dimethyl sulfoxide. The first halogen source is CsBr and PbBr2; the ratio of CsBr and PbBr2 to the organic solvent is 0.4 mmol: 0.4~0.8 mmol: 10~20 mL; The second halogen source is CsCl and PbCl2; the ratio of CsCl and PbCl2 to the organic solvent is 0.4 mmol: 0.4~0.8 mmol: 10~20 mL; The third halogen source is CsBr, CsCl and PbBr2; the ratio of CsBr, CsCl and PbBr2 to organic solvent is 0.3mmol:0.1mmol:0.4~0.8mmol:10~20mL; The volume ratio of the halogen source solvent to methyl α-bromophenylacetate is 2:1 to 8:1; The ratio of CsI to the total amount of halogen source solvent and methyl α-bromophenylacetate is 0.2~1 mmol:0.5~1 mL.

5. The preparation method according to claim 1, characterized in that, The antisolvent includes isopropanol; the volume ratio of the precursor solution to the antisolvent is 1:40 to 1:

70. The reprecipitation reaction was carried out at room temperature for 5-15 minutes. The solvent used for redispersion is toluene.

6. The perovskite quantum dots prepared by the preparation method according to any one of claims 1 to 5, characterized in that, The chemical composition is β-CsPbI 3-x-y Br x Cl y , where 0≤x<3, 0≤y<3, x+y<3, and x and y are not both 0.

7. The application of the perovskite quantum dots based on halogen composition regulation as described in claim 6 in the field of perovskite solar cells.

8. A perovskite solar cell, characterized in that, It includes a transparent conductive substrate, an electron transport layer, an absorption layer, a hole transport layer, and a metal electrode stacked sequentially, wherein the absorption layer is prepared from perovskite quantum dots based on halogen composition regulation as described in claim 6.

9. An optoelectronic device, characterized in that, It includes the perovskite solar cell of claim 8 and the light conversion film covering the surface of the perovskite solar cell.

10. The optoelectronic device according to claim 9, characterized in that, The optoelectronic devices include light-emitting devices, display devices, or battery devices.

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