Method for preparing inorganic perovskite thin film with assistance of cystamine dihydrochloride

Abstract

The invention discloses a cystamine dihydrochloride assisted preparation method of an inorganic perovskite film, and relates to the technical field of photoelectric materials and devices, and the method comprises the following specific steps: step 1, weighing cesium iodide, lead iodide and dimethylamine hydriodate as raw materials, selecting DMF as a solvent, then slowly adding the raw materials into the DMF solvent, and carrying out a reaction for 2-4 hours at the temperature of 50-60 DEG C; the preparation method has the advantages that cesium iodide, lead iodide and dimethylamine hydriodate in the inorganic perovskite precursor solution are selected to provide basic elements for construction of a perovskite crystal structure, and it is ensured that the film has basic photoelectric properties; the adhesive force between the film and the substrate is enhanced, the stress caused by the difference of thermal expansion coefficients is effectively relieved, the structural phase change of the film in a high-temperature environment is greatly inhibited, and the problem that the photoelectric property of the film is sharply reduced at a high temperature in the prior art is successfully solved.

Description

Technical Field

[0001] The invention relates to the technical field of optoelectronic materials and devices, and in particular to a method for preparing an inorganic perovskite film with the aid of cystamine dihydrochloride. Background Art

[0002] Inorganic perovskite materials have shown significant advantages such as enhanced thermal stability by replacing organic cations such as MA+ and FA+ with inorganic cations such as Cs+ at the A position. In recent years, they have attracted a lot of research interest. In fact, inorganic perovskite materials were synthesized as early as 1893, but it was not until around 2012 that the optoelectronic applications of inorganic perovskite materials began to attract widespread attention from researchers with the rapid development of organic-inorganic hybrid perovskite materials in the field of solar cells. In recent years, by adjusting and improving the crystal phase, particle morphology and coverage of the film, the research on inorganic perovskite solar cells has made certain progress. However, further improving the quality of the film is still the focus of current research. At the same time, the research on light-emitting diodes (LEDs) based on inorganic perovskite materials has become an important research frontier, attracting the attention of many research institutions. Research in this field also urgently needs to improve the quality of inorganic perovskite films.

[0003] The existing technology has certain defects. The first is poor thermal stability. Under high temperature environment, inorganic perovskite films may undergo structural phase transition, from a phase with good photoelectric properties to other phases, resulting in a sharp decline in its photoelectric performance. The difference in thermal expansion coefficient may cause stress between the film and the substrate. As the temperature changes, this stress may cause cracking, peeling and other problems in the film. Secondly, the inorganic perovskite film prepared by the existing technology is not dense and smooth, and cannot be applied to optoelectronic devices such as solar cells and light-emitting diodes. For this reason, we propose a method for preparing inorganic perovskite films with the assistance of cystamine dihydrochloride. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing an inorganic perovskite film with the assistance of cystamine dihydrochloride.

[0005] In order to solve the problems raised in the above background technology, the present invention provides the following technical solution: a method for preparing an inorganic perovskite film assisted by cystamine dihydrochloride, the method comprising the following specific steps:

[0006] Step 1, weighing cesium iodide, lead iodide and dimethylamine hydroiodide as raw materials, selecting DMF as a solvent, then slowly adding these raw materials into the DMF solvent, stirring at room temperature, to obtain an inorganic perovskite precursor solution;

[0007] Step 2, weighing cystamine dihydrochloride and dimethyl sulfoxide solvent, adding cystamine dihydrochloride to the dimethyl sulfoxide solvent and stirring to obtain a cystamine dihydrochloride solution;

[0008] Step 3, taking the prepared inorganic perovskite precursor solution, dividing it into two parts, A and B, and then slowly dropping the prepared cystamine dihydrochloride solution into the B solution, stirring at the same time during the dropping process, and continuously stirring after the dropping is completed to obtain a precursor mixed solution containing cystamine dihydrochloride;

[0009] Step 4: select a silicon wafer as a substrate, first soak it in a hydrofluoric acid solution to remove the oxide layer on the surface, rinse it with deionized water after soaking, and then sequentially put the silicon wafer substrate into deionized water, acetone, and ethanol for ultrasonic cleaning. After cleaning, blow dry it in a nitrogen atmosphere, and then place the treated silicon wafer substrate on a spin coater, take a solution A without adding cystamine dihydrochloride and drop it in the center of the substrate for pre-spin coating to spread the solution evenly, then take a solution B with cystamine dihydrochloride added and drop it in the center of the substrate, and then use a spin coater to perform spin coating to form a uniform film;

[0010] Step 5: Place the spin-coated film on a hot stage for preliminary annealing. During this process, the precursor partially reacts to form a preliminary crystal nucleus structure. Then, the film after preliminary annealing is transferred to a hot stage for secondary annealing. After these two steps of annealing, the remaining precursor reacts completely, completing the preparation of the main body of the inorganic perovskite film.

[0011] Step 6. After annealing, allow the film to cool naturally to room temperature on the hot stage, then use a solution mixed with deionized water and ethanol to gently rinse the surface of the film to remove impurities and unreacted substances that may remain on the surface of the film. Then, blow dry the cleaned film in a nitrogen atmosphere, and finally use vacuum packaging technology to encapsulate the film in a glass material.

[0012] As a further scheme of the present invention: in the step 1, 1.4 mol-1.6 mol of cesium iodide, 1.4 mol-1.6 mol of lead iodide and 1.3 mol-1.5 mol of dimethylamine hydroiodide are weighed, 1000uL-1200uL of DMF solvent is selected, and the stirring operation is carried out at a speed of 200r / min-300r / min for 1h-3h.

[0013] As a further solution of the present invention: in the step 2, 0.7 mol-0.8 mol of cystamine dihydrochloride is weighed, 500 mL-700 mL of dimethyl sulfoxide solvent is selected, and the stirring operation is carried out at a stirring speed of 150 r / min-300 r / min for 30 min-60 min to obtain a cystamine dihydrochloride solution with a concentration of 1.0 mol / L-1.6 mol / L.

[0014] As a further solution of the present invention: in the step three, the inorganic perovskite precursor solution is evenly divided into two parts, A and B, each with 500uL-6000uL, and then 25uL-30uL of the prepared cystamine dihydrochloride solution is slowly added to the B solution, and the solution is stirred at a speed of 150r / min-300r / min during the addition process, and the stirring is continued for 5min-15min after the addition is completed.

[0015] As a further solution of the present invention: in the step 4, the silicon wafer substrate is immersed in a hydrofluoric acid solution with a volume ratio of hydrofluoric acid to water of 1:10-20 for 3 min-5 min, and then rinsed with deionized water for 5-7 times, and the ultrasonic cleaning time is 8 min-15 min. After cleaning, it is blown dry in a nitrogen atmosphere.

[0016] As a further solution of the present invention: in the step 4, 40uL-60uL of solution A without cystamine dihydrochloride is added dropwise to the center of the substrate, and pre-spin coating is performed at a speed of 400r / min-600r / min for 3s-8s to spread the solution evenly, and then 40uL-60uL of solution B with cystamine dihydrochloride added is added dropwise to the center of the substrate, the spin coater speed is set to 3500r / min-4500r / min, the spin coating time is 25s-35s, and a uniform thin film is formed. During the spin coating process, the ambient humidity must be strictly controlled at 25%-50%, and the temperature must be 18°C-25°C.

[0017] As a further solution of the present invention: in the step five, the spin-coated film is first placed on a hot plate at 90°C-130°C for preliminary annealing, and the annealing time is controlled at 2min-4min. During this process, the precursor partially reacts to form a preliminary crystal nucleus structure.

[0018] As a further solution of the present invention: in the step five, the secondary annealing treatment is to transfer the film after the preliminary annealing to a hot stage at 160°C-180°C, the annealing time is 4min-6min, and during the annealing process, the heating rate is controlled at 8°C / min-20°C / min.

[0019] As a further solution of the present invention: in step 6, a solution prepared by mixing deionized water and ethanol in a volume ratio of 1:1-2 is used to wash the surface of the film, and the rinsing time is 8s-20s. The vacuum degree of the packaging environment needs to be controlled at 10 -3 Pa-10 - 6 Pa.

[0020] By adopting the above technical solution, compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. The present invention provides basic elements for constructing the perovskite crystal structure by selecting cesium iodide, lead iodide and dimethylamine hydroiodide in the inorganic perovskite precursor solution, ensuring that the film has basic photoelectric properties. The cystamine dihydrochloride in the cystamine dihydrochloride solution is complexed with the metal ions in the precursor solution to form a complex intermediate phase, which guides the orderly growth of the crystal during the film growth, significantly reduces crystal defects, makes the film more dense and smooth, improves the film quality, and is conducive to forming a smooth and dense film. At the same time, it enhances the adhesion between the film and the substrate, effectively alleviates the stress caused by the difference in thermal expansion coefficient, greatly inhibits the structural phase change of the film under high temperature environment, and successfully solves the problem of a sharp decline in the photoelectric performance of the film at high temperature in the prior art;

[0022] 2. In the spin coating film forming process, the present invention pre-spins the A solution without adding cystamine dihydrochloride to make the solution evenly spread on the substrate surface, optimize the chemical environment of the substrate, and create favorable conditions for the subsequent spin coating of the B solution with cystamine dihydrochloride added. During the spin coating process of the B solution, the cystamine dihydrochloride fully plays a role, further ensuring the density and flatness of the film, improving the thermal stability of the film, effectively avoiding the problems of film cracking and peeling caused by stress, ensuring the integrity and stability of the film, and extending the service life;

[0023] 3. The present invention promotes uniform formation of crystal nuclei at a suitable lower temperature through the first annealing, preliminarily stabilizes the film structure and enhances the adhesion to the substrate. The second annealing promotes complete reaction of the remaining precursor at a higher temperature, realizes complete crystal growth, optimizes the crystal structure and performance, and at the same time, cystamine dihydrochloride continuously stabilizes the structure, further improves the thermal stability of the film, effectively avoids cracking and peeling of the film, and the traditional film is obviously damaged, which strongly promotes its wide application in the field of optoelectronic devices such as solar cells and light-emitting diodes, and provides solid support for the development of related technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic diagram of a method step flow chart in an embodiment of the present invention;

[0025] Figure 2 Schematic diagram of the SEM morphology of the comparative sample and the sample with cystamine dihydrochloride added in the embodiment of the present invention;

[0026] Figure 3 This is a schematic diagram of XRD comparison between the comparative sample and the embodiment in the embodiment of the present invention;

[0027] Figure 4 It is a schematic diagram of the photoluminescence detection spectrum of the comparative example and the example in the embodiment of the present invention. DETAILED DESCRIPTION

[0028] The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention.

[0029] In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0030] Please see attached Figure 1 -Attached Figure 4 The present invention provides a method for preparing an inorganic perovskite film with the aid of cystamine dihydrochloride, the method comprising the following specific steps:

[0031] Step 1, weighing cesium iodide, lead iodide and dimethylamine hydroiodide as raw materials, selecting DMF as a solvent, then slowly adding these raw materials into the DMF solvent, stirring at room temperature, to obtain an inorganic perovskite precursor solution;

[0032] Step 2, weighing cystamine dihydrochloride and dimethyl sulfoxide solvent, adding cystamine dihydrochloride to the dimethyl sulfoxide solvent and stirring to obtain a cystamine dihydrochloride solution;

[0033] Step 3, taking the prepared inorganic perovskite precursor solution, dividing it into two parts, A and B, and then slowly dropping the prepared cystamine dihydrochloride solution into the B solution, stirring at the same time during the dropping process, and continuously stirring after the dropping is completed to obtain a precursor mixed solution containing cystamine dihydrochloride;

[0034] Step 4: select a silicon wafer as a substrate, first soak it in a hydrofluoric acid solution to remove the oxide layer on the surface, rinse it with deionized water after soaking, and then sequentially put the silicon wafer substrate into deionized water, acetone, and ethanol for ultrasonic cleaning. After cleaning, blow dry it in a nitrogen atmosphere, and then place the treated silicon wafer substrate on a spin coater, take a solution A without adding cystamine dihydrochloride and drop it in the center of the substrate for pre-spin coating to spread the solution evenly, then take a solution B with cystamine dihydrochloride added and drop it in the center of the substrate, and then use a spin coater to perform spin coating to form a uniform film;

[0035] Step 5: Place the spin-coated film on a hot stage for preliminary annealing. During this process, the precursor partially reacts to form a preliminary crystal nucleus structure. Then, the film after preliminary annealing is transferred to a hot stage for secondary annealing. After these two steps of annealing, the remaining precursor reacts completely, completing the preparation of the main body of the inorganic perovskite film.

[0036] Step 6. After annealing, allow the film to cool naturally to room temperature on the hot stage, then use a solution mixed with deionized water and ethanol to gently rinse the surface of the film to remove impurities and unreacted substances that may remain on the surface of the film. Then, blow dry the cleaned film in a nitrogen atmosphere, and finally use vacuum packaging technology to encapsulate the film in a glass material.

[0037] In one embodiment of the present invention: in step 1, 1.4 mol-1.6 mol of cesium iodide, 1.4 mol-1.6 mol of lead iodide and 1.3 mol-1.5 mol of dimethylamine hydroiodide are weighed, 1000 uL-1200 uL of DMF solvent is selected, and the stirring operation is carried out at a speed of 200 r / min-300 r / min for 1 h-3 h.

[0038] In one embodiment of the present invention: in step 2, 0.7 mol-0.8 mol of cystamine dihydrochloride is weighed, 500 mL-700 mL of dimethyl sulfoxide solvent is selected, and the stirring operation is carried out at a stirring speed of 150 r / min-300 r / min for 30 min-60 min to obtain a cystamine dihydrochloride solution with a concentration of 1.0 mol / L-1.6 mol / L.

[0039] In one embodiment of the present invention: in step three, the inorganic perovskite precursor solution is evenly divided into two parts, A and B, each with 500uL-6000uL, and then 25uL-30uL of the prepared cystamine dihydrochloride solution is slowly added to the B solution, and the mixture is stirred at a speed of 150r / min-300r / min during the addition process, and the stirring is continued for 5min-15min after the addition is completed.

[0040] In one embodiment of the present invention: in step 4, the silicon wafer substrate is immersed in a hydrofluoric acid solution with a volume ratio of hydrofluoric acid to water of 1:10-20 for 3 min-5 min, then rinsed with deionized water 5-7 times, and the ultrasonic cleaning time is 8 min-15 min. After cleaning, it is blown dry in a nitrogen atmosphere.

[0041] In one embodiment of the present invention: in step 4, 40uL-60uL of solution A without cystamine dihydrochloride is added dropwise to the center of the substrate, and pre-spin coating is performed at a speed of 400r / min-600r / min for 3s-8s to spread the solution evenly, and then 40uL-60uL of solution B with cystamine dihydrochloride added is added dropwise to the center of the substrate, the spin coater speed is set to 3500r / min-4500r / min, the spin coating time is 25s-35s, and a uniform thin film is formed. During the spin coating process, the ambient humidity must be strictly controlled at 25%-50%, and the temperature is 18°C-25°C.

[0042] In one embodiment of the present invention: in step five, the spin-coated film is first placed on a hot plate at 90°C-130°C for preliminary annealing, and the annealing time is controlled at 2min-4min. During this process, the precursor partially reacts to form a preliminary crystal nucleus structure.

[0043] In one embodiment of the present invention: in step five, the secondary annealing treatment is to transfer the film after the preliminary annealing to a hot stage at 160°C-180°C, the annealing time is 4min-6min, and during the annealing process, the heating rate is controlled at 8°C / min-20°C / min.

[0044] In one embodiment of the present invention: in step 6, a solution prepared by mixing deionized water and ethanol in a volume ratio of 1:1-2 is used to wash the surface of the film. The rinsing time is 8s-20s, and the vacuum degree of the packaging environment needs to be controlled at 10 -3 Pa-10 -6 Pa.

[0045] In one embodiment of the present invention: in step 1, a surfactant accounting for 0.1%-0.5% of the volume of the solvent can be added to the DMF solvent, and the surfactant is sodium dodecylbenzene sulfonate or polyvinyl pyrrolidone. During the stirring process, ultrasonic oscillation treatment is performed for 10min-30min, and the ultrasonic frequency is 20kHz-50kHz, which further promotes the dissolution and dispersion of the raw materials, reduces the agglomeration phenomenon in the precursor solution, and improves the stability of the precursor solution, thereby helping to form a more uniform and high-quality inorganic perovskite film.

[0046] In one embodiment of the present invention: in step 2, 0.05 mol-0.15 mol of metal organic framework material (MOFs) is added to the cystamine dihydrochloride solution, and the MOFs is ZIF-8 or MIL-101. During the stirring process, ultraviolet irradiation treatment is performed for 15 min-45 min, and the ultraviolet wavelength is 254 nm-365 nm. The impurity ions in the solution are adsorbed by the porous structure and adsorption performance of the MOFs material. At the same time, the ultraviolet irradiation promotes the synergistic effect between MOFs and cystamine dihydrochloride, changes the electronic structure of cystamine dihydrochloride, and enhances its complexing ability with metal ions in the precursor solution, thereby improving the quality and performance of the final film.

[0047] In one embodiment of the present invention: In step four, a layer of aluminum oxide or titanium dioxide film with a thickness of 1nm-5nm is grown on the surface of the silicon wafer substrate by atomic layer deposition (ALD) technology as a buffer layer, the ALD growth temperature is 80℃-150℃, the precursor pulse time is 0.1s-0.5s, the purge time is 5s-15s, and the number of cycles is 10-50 times. The buffer layer can effectively adjust the energy level difference between the silicon wafer substrate and the inorganic perovskite film, reduce the charge recombination at the interface, improve the charge transfer efficiency, and at the same time enhance the adhesion between the film and the substrate, further improving the stability and photoelectric properties of the film.

[0048] Example 1, please refer to the attached Figure 1 -Attached Figure 4, weigh 1.6 mol of cesium iodide, 1.6 mol of lead iodide and 1.5 mol of dimethylamine hydroiodide as raw materials, select 1200uL of DMF solvent, then slowly add these raw materials into DMF solvent, stir at 300r / min for 3h at room temperature (25℃) to obtain inorganic perovskite precursor solution, weigh 0.8 mol of cystamine dihydrochloride and 700mL of dimethyl sulfoxide solvent, add cystamine dihydrochloride into dimethyl sulfoxide solvent and stir for 60min at 300r / min to obtain a solution with a concentration of 1.6 mol l / L cystamine dihydrochloride solution, take the prepared inorganic perovskite precursor solution, divide it into two parts, A and B, each 6000uL, and then slowly add 30uL of the prepared cystamine dihydrochloride solution to the B solution, stir at a speed of 300r / min during the addition process, and continue to stir for 15min after the addition is completed to obtain a precursor mixed solution containing cystamine dihydrochloride, select a silicon wafer as a substrate, and soak the silicon wafer substrate in a hydrofluoric acid solution with a volume ratio of hydrofluoric acid to water of 1:20 for 5min Then rinse with deionized water for 7 times, and then put the silicon wafer substrate into deionized water, acetone, and ethanol for ultrasonic cleaning in turn. The ultrasonic cleaning time is 15 minutes. After cleaning, blow dry in a nitrogen atmosphere, and then place the treated silicon wafer substrate on a spin coater, take 60uL of solution A without cystamine dihydrochloride and drop it on the center of the substrate, pre-spin coat at a speed of 600r / min for 8s to spread the solution evenly, then take 60uL of solution B with cystamine dihydrochloride added and drop it on the center of the substrate, set the spin coater speed to 4 500r / min, spin coating time is 35s, to form a uniform film, during the spin coating process, strictly control the ambient humidity at 50%, the temperature at 25℃, the spin coated film is first placed on a hot stage at 130℃ for preliminary annealing, the annealing time is controlled at 4min, during this process, the precursor partially reacts to form a preliminary crystal nucleus structure, then the film after preliminary annealing is transferred to a hot stage at 180℃, the annealing time is 6min, and during the annealing process, the heating rate is controlled at 20℃ / min, after these two steps of annealing, the remaining precursors react completely, and the main body preparation of the inorganic perovskite film is completed, after the annealing is completed, let the film cool naturally to room temperature on the hot stage, and then use a solution mixed with deionized water and ethanol in a volume ratio of 1:2 to gently rinse the film surface, the rinsing time is 20s, remove the impurities and unreacted substances that may remain on the film surface, and then blow dry the cleaned film in a nitrogen atmosphere, and finally use vacuum packaging technology to encapsulate the film in a glass material, the vacuum degree of the packaging environment needs to be controlled at 10 -6 Pa.

[0049] Example 2, please refer to the attached Figure 1 -Attached Figure 4, weigh 1.4 mol of cesium iodide, 1.4 mol of lead iodide and 1.3 mol of dimethylamine hydroiodide as raw materials, select 1000uL of DMF solvent, then slowly add these raw materials into DMF solvent, stir at 200r / min for 1h at room temperature (20℃) to obtain inorganic perovskite precursor solution, weigh 0.7 mol of cystamine dihydrochloride and 500mL of dimethyl sulfoxide solvent, add cystamine dihydrochloride into dimethyl sulfoxide solvent and stir for 30min at 150r / min to obtain a solution with a concentration of 1.0 mol l / L cystamine dihydrochloride solution, take the prepared inorganic perovskite precursor solution, divide it into two parts, A and B, each 500uL, and then slowly add 25uL of the prepared cystamine dihydrochloride solution to the B solution, stir at a speed of 150r / min during the dropping process, and continue stirring for 5min after the dropping is completed to obtain a precursor mixed solution containing cystamine dihydrochloride, select a silicon wafer as a substrate, and soak the silicon wafer substrate in a hydrofluoric acid solution with a volume ratio of hydrofluoric acid to water of 1:10 for 3min, Then rinse with deionized water for 5 times, and then put the silicon wafer substrate into deionized water, acetone, and ethanol for ultrasonic cleaning in turn. The ultrasonic cleaning time is 8 minutes. After cleaning, blow dry in a nitrogen atmosphere, and then place the treated silicon wafer substrate on a spin coater, take 40uL of solution A without cystamine dihydrochloride and drop it on the center of the substrate, pre-spin coat at a speed of 400r / min for 3s to spread the solution evenly, then take 40uL of solution B with cystamine dihydrochloride added and drop it on the center of the substrate, set the spin coater speed to 3 500r / min, spin coating time is 25s, form a uniform film, during the spin coating process, strictly control the ambient humidity at 25%, the temperature is 18 ℃, the spin coated film is first placed on a 90 ℃ hot stage for preliminary annealing, the annealing time is controlled at 2min, during this process, the precursor partially reacts to form a preliminary crystal nucleus structure, then the film after preliminary annealing is transferred to a 160 ℃ hot stage, the annealing time is 4min, and during the annealing process, the heating rate is controlled at 8 ℃ / min, after these two steps of annealing, the remaining precursors are completely reacted, and the main body preparation of the inorganic perovskite film is completed, after the annealing is completed, let the film cool naturally to room temperature on the hot stage, and then use a solution mixed with deionized water and ethanol in a volume ratio of 1:1 to gently rinse the film surface, the rinsing time is 8s, remove the impurities and unreacted substances that may remain on the film surface, and then blow dry the cleaned film in a nitrogen atmosphere, and finally use vacuum packaging technology to encapsulate the film in a glass material, and the vacuum degree of the packaging environment needs to be controlled at 10 - 3 Pa.

[0050] For comparative examples, please refer to the attached Figure 1 -Attached Figure 4, using an inorganic halogen perovskite film (comparative sample) provided in the patent document with application publication number CN108525963A and titled "A method for preparing an inorganic halogen perovskite film", a method for preparing an inorganic perovskite film comprises the following steps: at 80-100°C, spraying the perovskite precursor liquid CsPbBr3 on the surface of a clean bottom electrode, spin coating the bottom electrode deposited with the perovskite CsPbBr3 while dripping a poor solvent, and annealing at 250-300°C to obtain an inorganic perovskite film, wherein the poor solvent is toluene or a mixed solvent of toluene and butyric acid.

[0051] As attached Figure 2 -Attached Figure 4 As shown, Example 1 and Example 2 improve the thermal stability of the film, avoid cracking and peeling, promote its wide application in the field of optoelectronic devices, provide strong support for the development of related technologies, and multiple technologies in each link work together to achieve good results in preparing inorganic perovskite films. The present invention has outstanding technical advantages and broad application prospects.

[0052] Although the present invention is disclosed as above in terms of preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing an inorganic perovskite film assisted by cystamine dihydrochloride, characterized in that: The method comprises the following specific steps: Step 1, weighing cesium iodide, lead iodide and dimethylamine hydroiodide as raw materials, selecting DMF as a solvent, then slowly adding these raw materials into the DMF solvent, stirring at room temperature, to obtain an inorganic perovskite precursor solution; Step 2, weighing cystamine dihydrochloride and dimethyl sulfoxide solvent, adding cystamine dihydrochloride to the dimethyl sulfoxide solvent and stirring to obtain a cystamine dihydrochloride solution; Step 3, taking the prepared inorganic perovskite precursor solution, dividing it into two parts, A and B, and then slowly dropping the prepared cystamine dihydrochloride solution into the B solution, stirring at the same time during the dropping process, and continuously stirring after the dropping is completed to obtain a precursor mixed solution containing cystamine dihydrochloride; Step 4: select a silicon wafer as a substrate, first soak it in a hydrofluoric acid solution, rinse it with deionized water after soaking, then sequentially put the silicon wafer substrate into deionized water, acetone, and ethanol for ultrasonic cleaning, blow dry it in a nitrogen atmosphere after cleaning, and then place the treated silicon wafer substrate on a spin coater, take a solution A without adding cystamine dihydrochloride and drop it in the center of the substrate for pre-spin coating to spread the solution evenly, then take a solution B with cystamine dihydrochloride added and drop it in the center of the substrate, and then use a spin coater to perform spin coating to form a uniform film; Step 5: placing the spin-coated film on a hot stage for preliminary annealing, and then transferring the film after preliminary annealing to the hot stage for secondary annealing to complete the main preparation of the inorganic perovskite film; Step 6. After annealing, allow the film to cool naturally to room temperature on the hot stage, then gently rinse the film surface with a solution mixed with deionized water and ethanol, then blow dry the cleaned film in a nitrogen atmosphere, and finally use vacuum packaging technology to encapsulate the film in a glass material.

2. The method for preparing an inorganic perovskite film assisted by cystamine dihydrochloride according to claim 1, characterized in that: In the step 1, 1.4 mol-1.6 mol of cesium iodide, 1.4 mol-1.6 mol of lead iodide and 1.3 mol-1.5 mol of dimethylamine hydroiodide are weighed, 1000 uL-1200 uL of DMF solvent is selected, and the stirring operation is carried out at a speed of 200 r / min-300 r / min for 1 h-3 h.

3. The method for preparing an inorganic perovskite film assisted by cystamine dihydrochloride according to claim 1, characterized in that: In the step 2, 0.7 mol-0.8 mol of cystamine dihydrochloride is weighed, 500 mL-700 mL of dimethyl sulfoxide solvent is selected, and stirring is performed at a stirring speed of 150 r / min-300 r / min for 30 min-60 min to obtain a cystamine dihydrochloride solution with a concentration of 1.0 mol / L-1.6 mol / L.

4. The method for preparing an inorganic perovskite film assisted by cystamine dihydrochloride according to claim 1, characterized in that: In the step 3, the inorganic perovskite precursor solution is evenly divided into two parts, A and B, each with 500uL-6000uL, and then 25uL-30uL of the prepared cystamine dihydrochloride solution is slowly added to the B solution, and the mixture is stirred at a speed of 150r / min-300r / min during the addition process, and the stirring is continued for 5min-15min after the addition is completed.

5. The method for preparing an inorganic perovskite film assisted by cystamine dihydrochloride according to claim 1, characterized in that: In the step 4, the silicon wafer substrate is immersed in a hydrofluoric acid solution with a volume ratio of hydrofluoric acid to water of 1:10-20 for 3-5 minutes, and then rinsed with deionized water for 5-7 times. The ultrasonic cleaning time is 8-15 minutes. After cleaning, it is blown dry in a nitrogen atmosphere.

6. The method for preparing an inorganic perovskite film assisted by cystamine dihydrochloride according to claim 1, characterized in that: In the step 4, 40uL-60uL of solution A without cystamine dihydrochloride is added dropwise to the center of the substrate, and pre-spin coating is performed at a speed of 400r / min-600r / min for 3s-8s to spread the solution evenly, and then 40uL-60uL of solution B with cystamine dihydrochloride added is added dropwise to the center of the substrate, the spin coater speed is set to 3500r / min-4500r / min, the spin coating time is 25s-35s, and a uniform thin film is formed. During the spin coating process, the ambient humidity must be strictly controlled at 25%-50%, and the temperature must be 18°C-25°C.

7. The method for preparing an inorganic perovskite thin film assisted by cystamine dihydrochloride according to claim 1, characterized in that: In the step 5, the spin-coated film is first placed on a hot plate at 90° C.-130° C. for preliminary annealing, and the annealing time is controlled at 2 min-4 min. During this process, the precursor partially reacts to form a preliminary crystal nucleus structure.

8. The method for preparing an inorganic perovskite film assisted by cystamine dihydrochloride according to claim 1, characterized in that: In the step 5, the secondary annealing treatment is to transfer the film after the preliminary annealing to a hot stage at 160°C-180°C, the annealing time is 4min-6min, and during the annealing process, the heating rate is controlled at 8°C / min-20°C / min.

9. The method for preparing an inorganic perovskite film assisted by cystamine dihydrochloride according to claim 1, characterized in that: In step 6, a solution prepared by mixing deionized water and ethanol in a volume ratio of 1:1-2 is used to wash the film surface. The rinsing time is 8s-20s. The vacuum degree of the packaging environment needs to be controlled at 10 -3 Pa-10 -6 Pa.

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