Epitaxial growth template, tin-based perovskite thin film and tin-based perovskite solar cell

Abstract

The invention discloses an epitaxial growth template, a tin-based perovskite thin film and a tin-based perovskite solar cell, and belongs to the technical field of perovskite solar cells. The epitaxial growth template is prepared by the following method: dissolving stannous iodide, stannous fluoride, organic ammonium salt containing conjugated aromatic rings and tin powder in a solvent, and then stirring for a period of time to obtain a precursor solution; and uniformly coating the precursor solution, and then annealing to obtain the epitaxial growth template. Aiming at rapid crystallization kinetics and disordered crystal orientation of the tin-based perovskite thin film, an epitaxial growth template is used for inducing epitaxial growth of three-dimensional perovskite, the crystallization rate of tin-based perovskite is delayed, growth of tin-based perovskite preferentially along a (100) crystal face is promoted, the density of defect states in a body is minimized, and the performance of the thin film is improved. The uniform tin-based perovskite thin film is ensured to be formed in a large range, and finally the photoelectric conversion efficiency of the tin-based perovskite solar cell is improved.

Description

Technical Field

[0001] This invention belongs to the field of perovskite solar cell technology, specifically relating to an epitaxial growth template, a tin-based perovskite thin film, and a tin-based perovskite solar cell. Background Technology

[0002] Organic-inorganic hybrid perovskite solar cells have seen rapid development due to their excellent photoelectric properties. However, lead-related biotoxicity poses potential hazards to the environment and human health. As candidate materials, tin-based perovskites, with their lower toxicity, are the most promising due to their comparable excellent photoelectric properties to lead-based perovskites and more suitable optical band gaps.

[0003] However, with Pb 2+ Compared to the inert 6s electron pair, Sn 2+ The presence of two active 5s electrons gives tin-based perovskites a stronger Lewis acidity, resulting in a relatively rapid crystallization rate. This uncontrolled crystallization process leads to disordered crystal orientation and a significant increase in defect states. These defects serve as both charge recombination centers and degradation sites, severely hindering the improvement of efficiency and stability in tin-based perovskite solar cells.

[0004] Inspired by orientation modulation in lead-based perovskites, numerous additives have been used to mitigate orientation disorder caused by rapid crystallization. However, residual additives and intermediate phases can reduce phase purity, adversely affecting device performance, while the modulation capability and versatility of single additives are limited. Epitaxial growth in lead-based perovskites has proven to be an effective strategy for controlling thin film crystallization kinetics, producing highly oriented films with low defect density. However, traditional PEA2SnI4-based epitaxial growth strategies are not significantly effective in slowing down the crystallization rate and promoting dominant orientation.

[0005] Therefore, developing a simple epitaxial growth strategy suitable for fabricating tin-based perovskite solar cells and adjusting the crystallization of perovskite along preferred orientation to minimize the density of trapped states are key to improving the performance of tin-based perovskite solar cells. Summary of the Invention

[0006] To address the problems of rapid crystallization kinetics and disordered crystal orientation in tin-based perovskite thin films mentioned in the background art, the present invention aims to provide an epitaxial growth template, a tin-based perovskite thin film, and a tin-based perovskite solar cell. The present invention develops an epitaxial growth template, which is used as a two-dimensional template to induce three-dimensional epitaxial growth of perovskite. This effectively slows down the crystallization rate of tin-based perovskite and promotes its preferential growth along the (100) crystal plane, thereby minimizing the bulk defect state density and ensuring the formation of a uniform tin-based perovskite thin film over a large area. Ultimately, this improves the photoelectric conversion efficiency and stability of tin-based perovskite solar cells.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: On one hand, the present invention provides an epitaxial growth template, which is prepared by the following method:

[0008] Stannous iodide (SnI2), stannous fluoride (SnF2), an organic ammonium salt containing a conjugated aromatic ring, and tin (Sn) powder are dissolved in a solvent and then stirred for a period of time to obtain a precursor solution.

[0009] The precursor solution was uniformly coated and then annealed to obtain an epitaxial growth template.

[0010] Organic ammonium salts containing conjugated aromatic rings can form low-dimensional perovskites with stannous iodide. The enhanced π-conjugation of these organic ammonium salts leads to the ordered arrangement of the low-dimensional perovskites. The transformation from thermodynamically stable low-dimensional perovskites to three-dimensional perovskites slows down the crystal growth rate, thereby inducing the slow and orderly epitaxial growth of three-dimensional perovskites. Furthermore, organic ammonium salts containing conjugated aromatic rings can also induce perovskite orientation by lowering the crystal surface energy.

[0011] Furthermore, the organic ammonium salt containing a conjugated aromatic ring is selected from at least one of 2-(naphthyl-2-yl)ethylamine hydroiodide (NEAI), 1-naphthylmethylamine iodide, and 2-naphthylmethylamine iodide;

[0012] The solvent is selected from at least one of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO).

[0013] Further, the molar ratio of stannous iodide (SnI2), stannous fluoride (SnF2), the organic ammonium salt containing a conjugated aromatic ring, and tin powder is 1:(0.05~0.2):(0.01~0.1):(0.01~0.2);

[0014] The ratio of the amount of the organic ammonium salt containing the conjugated aromatic ring to the solvent is (0.02 mol to 0.06 mol): 1 mL.

[0015] Furthermore, the stirring time is 2 hours to 12 hours;

[0016] The coating is spin coating, the spin coating speed is 5000 rpm to 7000 rpm, and the spin coating time is 20 s to 40 s;

[0017] The annealing temperature is 40℃~100℃, and the annealing time is 1min~10min.

[0018] Furthermore, the precursor solution needs to be filtered before use.

[0019] Furthermore, the purity of the organic ammonium salt containing a conjugated aromatic ring is above 97%.

[0020] On the other hand, the present invention provides a tin-based perovskite thin film, which is prepared by the following method:

[0021] Formamidin hydroiodide (FAI), ethylamine hydroiodide (EAI), and ethylenediamine dihydroiodate (EDAI2) were dissolved in a solvent to obtain a cationic solution;

[0022] The cationic solution is uniformly coated onto any of the epitaxial growth templates described above, and then annealed to obtain a tin-based perovskite film.

[0023] Further, the molar ratio of formamidin hydroiodide (FAI), ethylamine hydroiodide (EAI), and ethylenediamine dihydroiodate (EDAI2) is 1:(0.1-0.4):(0.01-0.05);

[0024] The solvent is selected from formic acid (FA) or isopropanol (IPA).

[0025] Furthermore, the coating is spin coating, the spin coating speed is 5000 rpm to 7000 rpm, and the spin coating time is 20 s to 40 s;

[0026] The annealing temperature is 40℃~100℃, and the annealing time is 5min~20min.

[0027] On the other hand, the present invention provides a tin-based perovskite solar cell, comprising a transparent conductive substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, a hole blocking layer, and a cathode electrode stacked sequentially from bottom to top;

[0028] The perovskite light-absorbing layer is any of the tin-based perovskite thin films described above.

[0029] Furthermore, the transparent conductive substrate is selected from ITO conductive glass or FTO conductive glass;

[0030] The hole transport layer is made of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) (PEDOT:PSS);

[0031] The electron transport layer is made of at least one of fullerene (C60) and fullerene derivatives, wherein the fullerene derivative includes indanedione-C. 60 Biadduct (ICBA), [6,6]-phenyl-C 61 Isomethyl butyrate (PCBM);

[0032] The material used in the hole blocking layer includes one of copper bath (BCP) and polyethyleneimine (PEI);

[0033] The cathode electrode includes a silver (Ag) electrode.

[0034] Furthermore, the hole transport layer has a thickness of 30nm to 40nm; the perovskite light-absorbing layer has a thickness of 200nm to 400nm; the electron transport layer has a thickness of 30nm to 40nm; the hole blocking layer has a thickness of 8nm to 10nm; and the cathode electrode has a thickness of 100nm to 110nm.

[0035] Furthermore, this invention provides a method for preparing a tin-based perovskite solar cell, comprising the following steps:

[0036] (1) Pre-treatment of transparent conductive substrate;

[0037] (2) Coat the solution of the material used for the hole transport layer onto the pretreated transparent conductive substrate obtained in step (1), and then anneal it to obtain the hole transport layer.

[0038] (3) Dissolve stannous iodide (SnI2), stannous fluoride (SnF2), an organic ammonium salt containing a conjugated aromatic ring, and tin powder in a solvent, and then stir for a period of time to obtain a precursor solution; filter the precursor solution and uniformly coat it on the hole transport layer, and then anneal it to obtain an epitaxial growth template; dissolve formamidinium hydroiodate (FAI), ethylamine hydroiodate (EAI), and ethylenediamine dihydroiodate (EDAI2) in a solvent to obtain a cationic solution; uniformly coat the cationic solution on the epitaxial growth template, and then anneal it to obtain a tin-based perovskite film;

[0039] (4) Prepare a solution of the material used for the electron transport layer, coat the solution of the material used for the electron transport layer onto the tin-based perovskite film prepared in step (3), and then anneal it to obtain the electron transport layer;

[0040] (5) Prepare a solution of the material used for the hole blocking layer, and coat the solution of the material used for the hole blocking layer onto the electron transport layer prepared in step (4) to obtain the hole blocking layer;

[0041] (6) A cathode electrode was prepared on the hole blocking layer by vacuum evaporation to obtain a tin-based perovskite solar cell.

[0042] Further, the coating in step (2) is spin coating, the spin coating speed is 6000rpm~8000rpm, the spin coating time is 30s~60s; the annealing temperature is 130℃~150℃, and the annealing time is 10min~30min.

[0043] Further, the coating of the precursor solution in step (3) is spin coating, the spin coating speed is 5000 rpm to 7000 rpm, the spin coating time is 20 s to 40 s; the annealing temperature is 40 ℃ to 100 ℃, and the annealing time is 1 min to 10 min.

[0044] The coating of the cation solution in step (3) is spin coating, the spin coating speed is 5000 rpm to 7000 rpm, the spin coating time is 20 s to 40 s; the annealing temperature is 40 ℃ to 100 ℃, and the annealing time is 5 min to 20 min.

[0045] Further, the coating in step (4) is spin coating, the spin coating speed is 1000rpm~3000rpm, the spin coating time is 20s~40s, the annealing temperature is 40℃~100℃, and the annealing time is 5min~30min.

[0046] Furthermore, the coating in step (5) is spin coating, the spin coating speed is 3000 rpm to 5000 rpm, and the spin coating time is 20 s to 40 s.

[0047] The principle of this invention is as follows: By introducing an organic ammonium salt containing a conjugated aromatic ring to react with SnI2, a two-dimensional template A2SnI4 (where A is an organic ammonium cation containing a conjugated aromatic ring) is pre-generated. Based on epitaxial growth theory, this ordered two-dimensional perovskite template plays a crucial role in the preferred orientation of the subsequently formed three-dimensional perovskite. On the one hand, the three-dimensional perovskite grown based on the A2SnI4 template inherits the directional arrangement characteristics of two-dimensional crystals, reducing lattice orientation mismatch, thereby forming a tin-based perovskite with a preferred orientation on the (100) crystal plane. Furthermore, according to Wulff's structural theory, AI (where A is an organic ammonium cation containing a conjugated aromatic ring) can also induce the orientation of the perovskite by reducing the crystal surface energy. On the other hand, after A2SnI4 participates in the reaction with FAI, it is further transformed into two-dimensional perovskites with different n values, and finally undergoes a non-self-heating mechanical process to transform into FASnI3. This transformation process significantly slows down the crystal growth rate, thereby achieving a significant reduction in the defect state density.

[0048] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0049] (1) This invention develops a simple epitaxial growth strategy to regulate the crystallization kinetics of tin-based perovskites. For the first time, it utilizes A2SnI4, generated by the reaction of an organic ammonium salt containing a conjugated aromatic ring with SnI2, as a template for the epitaxial growth of three-dimensional tin-based perovskites. The organic ammonium salt with enhanced π-conjugation successfully replaces the traditional 2-phenylethylamine hydroiodate (PEAI), achieving an ordered arrangement of three-dimensional perovskites. This not only optimizes the carrier transport kinetics but also ensures the formation of uniform tin-based perovskite films over a large area.

[0050] (2) The tin-based perovskite solar cell provided by this invention has high carrier lifetime and low defect state density, at 0.04 cm⁻¹ 2 With 1cm 2 The photoelectric conversion efficiencies achieved were 14.03% and 12.44% respectively over the effective area.

[0051] (3) The preparation method of the present invention is relatively simple, easy to operate, low in energy consumption, and has universality, making it suitable for widespread application. Attached Figure Description

[0052] Figure 1 Schematic diagrams of the tin-based perovskite solar cell structures prepared in Examples 4-7 and Comparative Examples 5 and 6 of the present invention;

[0053] Figure 2 Grazing incidence X-ray diffraction patterns of the tin-based perovskite films prepared in Example 2 and Comparative Examples 1 and 2 of this invention;

[0054] Figure 3 These are time-resolved photoluminescence images of the tin-based perovskite thin films prepared in Example 2 and Comparative Examples 1 and 2 of this invention.

[0055] Figure 4 This is a schematic diagram of the selected positions for grazing incidence X-ray diffraction tests in Embodiment 3 and Comparative Examples 3 and 4 of the present invention.

[0056] Figure 5 Grazing incidence X-ray diffraction patterns of the tin-based perovskite films prepared in Example 3 and Comparative Examples 3 and 4 of this invention;

[0057] Figure 6 The electrochemical impedance spectroscopy spectra of the tin-based perovskite solar cells prepared in Examples 4-6 and Comparative Examples 5 and 6 of this invention are shown.

[0058] Figure 7 The current-voltage characteristic curves of the tin-based perovskite solar cells prepared in Example 5 and Comparative Examples 5 and 6 of this invention are shown.

[0059] Figure 8This is a current-voltage characteristic curve of the tin-based perovskite solar cell prepared in Example 7 of the present invention. Detailed Implementation

[0060] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0061] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which this invention pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.

[0062] Example 1

[0063] Preparation of epitaxial growth template:

[0064] (1) The 1.5cm×1.5cm etched ITO conductive glass substrate was ultrasonically cleaned in aqueous solution of detergent, acetone, deionized water and isopropanol for 15min respectively. Then it was dried with N2 and placed in a plasma cleaner to treat the ITO substrate with UV-ozone for 10min.

[0065] (2) Stannous iodide (SnI2), stannous fluoride (SnF2), 2-(naphthyl-2-yl)ethylamine hydroiodate (NEAI) and tin (Sn) powder were dissolved in N,N-dimethylformamide (DMF) in a molar ratio of 1:0.1:0.05:0.05 and stirred for 4 h to obtain a precursor solution. The precursor solution was filtered and spin-coated (7000 rpm for 30 s) onto a pretreated ITO conductive glass and then annealed (70 °C for 1 min) to obtain an epitaxial growth template.

[0066] Example 2

[0067] Preparation of tin-based perovskite thin films: (1) A 1.5cm×1.5cm etched ITO conductive glass substrate was ultrasonically treated for 15min in aqueous solution of detergent, acetone, deionized water and isopropanol respectively. Then it was dried with N2 and placed in a plasma cleaner to be treated with UV-ozone for 10min.

[0068] (2) Stannous iodide (SnI2), stannous fluoride (SnF2), 2-(naphthyl-2-yl)ethylamine hydroiodate (NEAI), and tin (Sn) powder were dissolved in N,N-dimethylformamide (DMF) at a molar ratio of 1:0.1:0.05:0.05, and then stirred for 4 h to obtain a precursor solution; at the same time, formamidinium hydroiodate (FAI), ethylamine hydroiodate (EAI), and ethylenediamine dihydroiodate (EDAI2) were dissolved in formic acid (FA) at a molar ratio of 1:0.25:0.01 to obtain a cationic solution for later use. Among them, 2-(naphthyl-2-yl)ethylamine hydroiodate (NEAI) has the molecular structure shown in formula (1):

[0069]

[0070] (3) The precursor solution prepared in step (2) is filtered and spin-coated (7000 rpm, 30 s) onto the pretreated ITO conductive glass, and then annealed (70 °C, 1 min) to obtain an epitaxial growth template.

[0071] (4) The cationic solution prepared in step (2) was spin-coated (7000 rpm, 30 s) onto the surface of the epitaxial growth template, and then annealed (70 °C, 10 min) to obtain a 250 nm tin-based perovskite film.

[0072] Example 3

[0073] The preparation method in Example 3 is generally the same as that in Example 2. The difference is that in step (1), the ITO conductive glass is changed from 1.5cm × 1.5cm to 2.5cm × 2.5cm.

[0074] Example 4

[0075] A tin-based perovskite solar cell comprises, from bottom to top, a transparent conductive substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, a hole blocking layer, and a cathode electrode, stacked sequentially. The perovskite light-absorbing layer is a tin-based perovskite thin film. The transparent conductive substrate is selected from ITO conductive glass. The hole transport layer is made of poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid). The electron transport layer is made of ICBA. The hole blocking layer is made of BCP. The cathode electrode is a silver electrode.

[0076] Fabrication of tin-based perovskite solar cells:

[0077] (1) Pretreatment of transparent conductive substrate: The 1.5cm×1.5cm etched ITO conductive glass substrate was ultrasonically treated for 15min in aqueous solution of detergent, acetone, deionized water and isopropanol respectively. Then it was dried with N2 and placed in a plasma cleaner to treat the ITO substrate with UV-ozone for 10min.

[0078] (2) Preparation of the hole transport layer:

[0079] Preparation of hole transport layer: A poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonic acid) solution (PEDOT:PSS) was filtered and spin-coated (6000 rpm, 60 s) onto a pretreated ITO conductive glass, and then annealed (140 °C, 20 min) to obtain a 30 nm PEDOT:PSS layer.

[0080] (3) Preparation of the perovskite light-absorbing layer:

[0081] Preparation of precursor solution: Stannous iodide (SnI2), stannous fluoride (SnF2), 2-(naphthyl-2-yl)ethylamine hydroiodide (NEAI) and tin (Sn) powder were dissolved in N,N-dimethylformamide (DMF) at a molar ratio of 1:0.1:0.025:0.05, and then stirred for 4 hours to obtain the precursor solution for later use.

[0082] Preparation of cationic solution: Dissolve formamidin hydroiodide (FAI), ethylamine hydroiodide (EAI), and ethylenediamine dihydroiodate (EDAI2) in formic acid (FA) at a molar ratio of 1:0.25:0.01 to obtain a cationic solution for later use.

[0083] Preparation of epitaxial growth template: The precursor solution was filtered and spin-coated (7000 rpm, 30 s) onto the surface of the PEDOT:PSS layer, and then annealed (70℃, 1 min) to obtain the epitaxial growth template.

[0084] Preparation of tin-based perovskite thin films: A cationic solution was spin-coated (7000 rpm, 30 s) onto the surface of an epitaxial growth template, and then annealed (70 °C, 10 min) to obtain a 250 nm tin-based perovskite thin film.

[0085] (4) Fabrication of the electron transport layer:

[0086] Preparation of transport layer solution: Dissolve 18 mg ICBA powder thoroughly in 1 mL of chlorobenzene to obtain ICBA solution.

[0087] Preparation of the electron transport layer: ICBA solution was spin-coated (1200 rpm, 30 s) onto the surface of a tin-based perovskite film, and then annealed (70 °C, 10 min) to obtain a 30 nm ICBA layer.

[0088] (5) Preparation of hole blocking layer:

[0089] Preparation of barrier layer solution: Dissolve 0.5 mg BCP in 1 mL of isopropanol to prepare BCP solution.

[0090] Preparation of hole blocking layer: BCP solution was spin-coated (4500 rpm, 30 s) onto the surface of electron transport layer to obtain an 8 nm hole blocking layer.

[0091] (6) Evaporation of metal electrode: The product obtained in step (5) is placed in an evaporation apparatus and Ag is vapor-deposited on the surface of the hole blocking layer under high vacuum to obtain a 100nm metal electrode Ag.

[0092] Example 5

[0093] The preparation method in Example 5 is generally the same as that in Example 4. The difference is that the molar ratio in the precursor solution in step (3) is changed to SnI2:SnF2:NEAI:Sn powder = 1:0.1:0.05:0.05.

[0094] Example 6

[0095] The preparation method in Example 6 is generally the same as that in Example 4. The difference is that the molar ratio in the precursor solution in step (3) is changed to SnI2:SnF2:NEAI:Sn powder = 1:0.1:0.075:0.05.

[0096] Example 7

[0097] The preparation method in Example 7 is generally the same as that in Example 5. The difference is that in step (1), the ITO conductive glass is changed from 1.5cm × 1.5cm to 2.5cm × 2.5cm.

[0098] The tin-based perovskite solar cells prepared in Examples 4-7 have the following structures: Figure 1 As shown.

[0099] Comparative Example 1

[0100] The preparation method in Comparative Example 1 is generally the same as that in Example 2. The difference is that NEAI is not added to the precursor solution in step (2), that is, the precursor solution composition is SnI2:SnF2:Sn powder = 1:0.1:0.05.

[0101] Comparative Example 2

[0102] The preparation method in Comparative Example 2 is generally the same as that in Example 2. The difference is that NEAI in the precursor solution in step (2) is replaced with PEAI, that is, the precursor solution composition is SnI2:SnF2:PEAI:Sn powder = 1:0.1:0.05:0.05. PEAI has the molecular structure shown in formula (2):

[0103]

[0104] The tin-based perovskite films prepared in Example 2 and Comparative Examples 1 and 2 were subjected to grazing incidence X-ray diffraction and time-resolved photoluminescence tests, and the results are as follows: Figure 2 , Figure 3 As shown. From Figure 2 As can be seen from the data, the (100) crystallinity of the tin-based perovskite thin film prepared based on the epitaxial growth template is significantly improved. Figure 3 As can be seen, the carrier lifetime of the tin-based perovskite film prepared based on the epitaxial growth template is increased. These results demonstrate that the quality of the tin-based perovskite film prepared based on the epitaxial growth template is significantly improved.

[0105] Comparative Example 3

[0106] The preparation method in Comparative Example 3 is generally the same as that in Example 3. The difference is that NEAI is not added to the precursor solution in step (2), that is, the precursor solution composition is SnI2:SnF2:Sn powder = 1:0.1:0.05.

[0107] Comparative Example 4

[0108] The preparation method in Comparative Example 4 is generally the same as that in Example 3. The difference is that NEAI in the precursor solution in step (2) is replaced with PEAI, that is, the composition of the SnI2 precursor solution is SnI2:SnF2:PEAI:Sn powder = 1:0.1:0.05:0.05.

[0109] The tin-based perovskite films prepared in Example 3 and Comparative Examples 3 and 4 were taken as follows: Figure 4 Grazing incidence X-ray diffraction tests were performed at 16 different locations, and the results are as follows: Figure 5 As shown. From Figure 5 As can be seen from the data, compared with other tin-based perovskite films, the tin-based perovskite film prepared based on the epitaxial growth template exhibits stronger and more uniform (100) diffraction peaks, and there are no diffraction peaks of SnI2, which indicates that its overall quality has been uniformly improved.

[0110] Comparative Example 5

[0111] The preparation method in Comparative Example 5 is generally the same as that in Example 5. The difference is that NEAI is not added to the precursor solution in step (3), that is, the precursor solution composition is SnI2:SnF2:Sn powder = 1:0.1:0.05.

[0112] Comparative Example 6

[0113] The preparation method in Comparative Example 6 is generally the same as that in Example 5. The difference is that NEAI in the precursor solution in step (3) is replaced with PEAI, that is, the precursor solution composition is SnI2:SnF2:PEAI:Sn powder = 1:0.1:0.05:0.05.

[0114] The tin-based perovskite solar cells prepared in Comparative Examples 5-6 have the following structures: Figure 1 As shown.

[0115] Electrochemical impedance spectroscopy was performed on the tin-based perovskite solar cells prepared in Examples 4-6 and Comparative Examples 5 and 6. The results are as follows: Figure 6 As shown. From Figure 6 As can be seen, the tin-based perovskite solar cell prepared based on the epitaxial growth template has a larger recombination resistance and better charge transport performance. Furthermore, it can be seen that the tin-based perovskite solar cell prepared in Example 5 experiences greater recombination resistance compared to Examples 4 and 6; that is, when SnI2:SnF2:NEAl:Sn powder = 1:0.1:0.05:0.05, the prepared tin-based perovskite solar cell exhibits the best charge transport performance.

[0116] Based on the above analysis, the photoelectric conversion efficiency of the perovskite solar cells prepared in Example 5 and Comparative Examples 5 and 6 was tested under standard sunlight conditions (AM 1.5G, 100mW / cm²) using a solar simulator. 2 The effective area is 0.04 cm². 2 Current-voltage (JV) performance was tested at a scan speed of 20 mV / s. The test results are shown in Table 1 and... Figure 7 As shown in Table 1 and Figure 7 It can be seen that the tin-based perovskite solar cell prepared based on the epitaxial growth template has the best performance, with a conversion efficiency of 14.03%, which is significantly better than comparative examples 5 and 6.

[0117] Table 1 Performance parameters of tin-based perovskite solar cells

[0118] Open circuit voltage (V) <![CDATA[Short-circuit current (mA / cm 2 )]]> Fill factor (%) Conversion efficiency (%) Example 5 0.95 20.64 71.71 14.03 Comparative Example 5 0.77 17.54 68.27 9.27 Comparative Example 6 0.91 19.81 69.32 12.46

[0119] The quality of tin-based perovskite thin films and the performance of corresponding solar cells prepared using epitaxial growth templates are significantly improved. This is because the (100) crystallinity of the films prepared using this method is greatly increased, and the internal defect state density is significantly reduced. Conversely, the photoelectric conversion efficiency of tin-based perovskite solar cells prepared without PEAI or NEAI and based on PEA2SnI4 is relatively low, reflecting the superiority of the preparation method based on epitaxial growth templates.

[0120] The perovskite solar cell prepared in Example 7 was tested for photoelectric conversion efficiency under standard sunlight conditions (AM 1.5G, 100mW / cm²) using a solar simulator. 2 The effective area is 1.00 cm². 2 Current-voltage (JV) performance was tested at a scan speed of 20 mV / s. The test results are as follows: Figure 8 As shown, from Figure 8 As can be seen, the conversion efficiency of the tin-based perovskite solar cell prepared based on the epitaxial growth template can reach 12.44%.

[0121] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and various changes or modifications can be made to these embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is defined only by the appended claims.

Claims

1. An epitaxial growth template, characterized in that, It is prepared by the following method: Stannous iodide, stannous fluoride, an organic ammonium salt containing a conjugated aromatic ring, and tin powder are dissolved in a solvent and then stirred for a period of time to obtain a precursor solution. The precursor solution was uniformly coated and then annealed to obtain an epitaxial growth template.

2. The epitaxial growth template according to claim 1, characterized in that, The organic ammonium salt containing a conjugated aromatic ring is selected from at least one of 2-(naphthyl-2-yl)ethylamine hydroiodate, 1-naphthylmethylamine iodide, and 2-naphthylmethylamine iodide; The solvent is selected from at least one of N,N-dimethylformamide and dimethyl sulfoxide.

3. The epitaxial growth template according to claim 1, characterized in that, The molar ratio of stannous iodide, stannous fluoride, organic ammonium salt containing a conjugated aromatic ring, and tin powder is 1:(0.05-0.2):(0.01-0.1):(0.01-0.2).

4. The epitaxial growth template according to claim 1, characterized in that, The stirring time is 2 hours to 12 hours; The coating is spin coating, the spin coating speed is 5000 rpm to 7000 rpm, and the spin coating time is 20 s to 40 s; The annealing temperature is 40℃~100℃, and the annealing time is 1min~10min.

5. A tin-based perovskite thin film, characterized in that, It is prepared by the following method: Formamidin hydroiodide, ethylamine hydroiodide, and ethylenediamine dihydroiodate are dissolved in a solvent to obtain a cationic solution; The cationic solution is uniformly coated onto the epitaxial growth template according to any one of claims 1-4, and then annealed to obtain a tin-based perovskite film.

6. The tin-based perovskite thin film according to claim 5, characterized in that, The molar ratio of formamidin hydroiodate, ethylamine hydroiodate, and ethylenediamine dihydroiodate is 1:(0.1-0.4):(0.01-0.05). The solvent is selected from formic acid or isopropanol.

7. The tin-based perovskite thin film according to claim 5, characterized in that, The coating is spin coating, the spin coating speed is 5000 rpm to 7000 rpm, and the spin coating time is 20 s to 40 s; The annealing temperature is 40℃~100℃, and the annealing time is 5min~20min.

8. A tin-based perovskite solar cell, characterized in that, It includes a transparent conductive substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, a hole blocking layer, and a cathode electrode, which are stacked sequentially from bottom to top; The perovskite light-absorbing layer is the tin-based perovskite thin film according to any one of claims 5-7.

9. The tin-based perovskite solar cell according to claim 8, characterized in that, The transparent conductive substrate is selected from ITO conductive glass or FTO conductive glass. The hole transport layer is made of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid); The electron transport layer is made of at least one of fullerenes and fullerene derivatives, wherein the fullerene derivatives include indanedion-C. 60 Biadduct, [6,6]-phenyl-C 61 - Isomethyl butyrate; The material used in the hole blocking layer includes one of copper bath and polyethyleneimine; The cathode electrode includes a silver electrode.

10. The tin-based perovskite solar cell according to claim 8, characterized in that, The hole transport layer has a thickness of 30 nm to 40 nm; the perovskite light-absorbing layer has a thickness of 200 nm to 400 nm; the electron transport layer has a thickness of 30 nm to 40 nm; the hole blocking layer has a thickness of 8 nm to 10 nm; and the cathode electrode has a thickness of 100 nm to 110 nm.

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