Method for regulating dimension of three-source co-evaporated perovskite thin film and application thereof

Abstract

The application provides a method for regulating the dimension of a three-source co-evaporated perovskite film and an application thereof, and belongs to the technical field of perovskite solar cells. A large cation R-NH3I, PbI2 and FAI are co-evaporated to form (R-NH3)2(FA) n‑1 Pb n I 3n+1 PbI2 on a substrate, and the (R-NH3)2(FA) n‑1 Pb n I 3n+1 I film is annealed in air for 20 min. The dimension of the perovskite film is regulated by changing the annealing temperature. The post-annealing treatment step of the application helps to improve the quality of the perovskite film and provides the required energy for forming different dimensional structures. The dimension of the perovskite film is regulated only by regulating the post-annealing temperature, without the need for fine regulation of the evaporation rate, cavity gas pressure and other process parameters in the gas-phase co-evaporation process, and the operation is simple and highly repeatable.

Description

Technical Field

[0001] This invention belongs to the field of perovskite solar cell technology, specifically relating to a method for controlling the dimensions of a three-source co-evaporated perovskite thin film and its application. Background Technology

[0002] As a major representative of third-generation solar cell materials, perovskite has undergone rapid development over the past eleven years. The reported energy conversion efficiency of single-junction perovskite solar cells has reached 26.14%, while that of tandem perovskite solar cells has reached 33.9%, surpassing mature polycrystalline silicon solar cells and most second-generation thin-film solar cells. It is a rising star in the field of high-performance and low-cost photovoltaics.

[0003] Currently, the preparation of perovskite thin films is mainly divided into solution deposition and vapor phase deposition. Among them, vapor phase deposition is mainly divided into single-source deposition, multi-source co-deposition, and sequential deposition. Compared with the traditional spin coating method, vapor phase deposition has several unique advantages: (1) No or less solvent involved; in solution deposition, high-boiling-point solvents still remain in the perovskite after annealing, which can lead to phase instability. (2) Scalability; the molecular diffusion rate of gas phase reactants is faster, making the reaction more thorough and reproducible. (3) Easy to integrate with other solar cells; for example, thermal evaporation can be used to prepare other thin films and can also be used to prepare stacked devices with other solar cells. The above advantages indicate that vapor phase deposition has a promising future in the preparation of perovskite photovoltaic thin films.

[0004] In the fabrication of perovskite solar cells, the dimension of the perovskite absorber layer determines its bandgap, optical properties, electron transport performance, and environmental stability, making it one of the key parameters affecting its photoelectric conversion efficiency. In solution methods, many strategies based on dimension control have been disclosed, such as molecular design using long-chain organic cations, additive engineering, and controlling crystallization kinetics. These strategies have effectively controlled the dimension of perovskite films, thereby improving the photoelectric performance of the perovskite absorber layer. For example, Yang et al. (Yang R, Li R, Cao Y, et al. Oriented Quasi-2D Perovskites for High Performance Optoelectronic Devices[J]. Advanced Materials, 2018, 30(51).) obtained a dimensionally ordered structure by introducing 3BA (3-bromobenzyl) cations. The bottom of the film is a vertically oriented small n-value phase, and the top is an ordered crystalline large n-value phase. In the field of vapor deposition, researchers typically employ sequential vapor deposition to control process parameters such as the relative evaporation mass of the precursor and the evaporation reaction time, thereby controlling the dimensionality of perovskites (Li X, Lin D, Chen Z, et al. Structural Regulation for Highly Efficient and Stable Perovskite Solar Cells via Mixed-Vapor Deposition[J].ACS Applied Energy Materials, 2020, 3(7):6544-51.). However, research on dimensionality control in perovskite films prepared by multi-source co-evaporation is almost nonexistent. This may be because it is difficult to control the composition during the evaporation process, and the organic source has strong volatility, making it difficult to control the evaporation rate of the organic source and ensuring the crystal quality of the final film.

[0005] Therefore, there is an urgent need for a simple and operable method to control the dimensionality of perovskite thin films in the vapor deposition process. Summary of the Invention

[0006] To address the technical problems existing in the prior art, this invention provides a method for controlling the dimensions of perovskite thin films through three-source co-evaporation and its application, using the three-source co-evaporation method to prepare (R-NH3)2(FA) films with different large cations. n-1 Pb n I 3n+1 The dimensional control of perovskite thin films (n>1) can be achieved by adjusting the post-annealing temperature, and the operation method is simple and easy to implement.

[0007] To achieve the above objectives, the technical method employed in this invention is as follows:

[0008] A method for controlling the dimensionality of three-source co-evaporated perovskite thin films, specifically:

[0009] (R-NH3)2(FA) is deposited on a substrate by co-evaporation of the large cations R-NH3I, PbI2 (lead iodide), and FAI (formamidinium iodide). n-1 Pb n I 3n+1 Perovskite thin film, n>1; then (R-NH3)2(FA) obtained by vapor deposition. n-1 Pb n I 3n+1 The perovskite film was annealed in air for 20 minutes, and the (R-NH3)2(FA) was controlled by changing the annealing temperature. n-1 Pb n I 3n+1 The dimensions of the perovskite thin film; wherein, the R-NH3I is specifically PMAI (phenylmethyl iodide), PEAI (phenylethyl iodide), or BAI (butyl iodide).

[0010] Furthermore, during the three-source co-evaporation, the mass ratio of the evaporation sources R-NH3I, PbI2, and FAI is (0.1–0.5):1:1.

[0011] Furthermore, the evaporation rate of the PbI2 is... The evaporation rate of FAI is

[0012] Furthermore, the evaporation rate of the PMAI is The evaporation rate of PEAI is The evaporation rate of BAI is

[0013] Furthermore, the cavity pressure during three-source co-distillation is 1.0 × 10⁻⁶. -3 ~2.5×10 -3 Pa.

[0014] Furthermore, the (R-NH3)2(FA) obtained by vapor deposition n-1 Pb n I 3n+1 The thickness of the perovskite thin film is 500–600 nm.

[0015] Furthermore, when R-NH3I is PMAI, the vapor-deposited (PMA)2(FA) n-1 Pb n I 3n+1 After annealing at temperatures below 80°C, the perovskite film is composed of a mixed phase of two-dimensional and three-dimensional perovskite; after annealing at temperatures above or equal to 80°C, its composition is entirely three-dimensional perovskite.

[0016] Furthermore, when the R-NH3I is PEAI, the resulting (PEA)2(FA) is obtained by vapor deposition. n-1 Pb n I 3n+1 After annealing at temperatures below 80°C, the perovskite film is composed of a mixed phase of two-dimensional and three-dimensional perovskite; after annealing at temperatures above or equal to 80°C, its composition is entirely three-dimensional perovskite.

[0017] Furthermore, when the R-NH3I is BAI, the resulting (BA)2(FA) is obtained by vapor deposition. n-1 Pb n I 3n+1 After annealing at temperatures greater than 40°C and less than 150°C, the perovskite film is composed of a mixed phase of two-dimensional and three-dimensional perovskite; after annealing at temperatures less than or equal to 40°C or greater than or equal to 150°C, its composition is entirely three-dimensional perovskite.

[0018] This invention provides the obtained dimensionally modified (R-NH3)2(FA) n-1 Pb n I 3n+1 Application of perovskite thin films in perovskite solar cells.

[0019] A perovskite solar cell includes a substrate, an electron transport layer, and a dimensionally modulated (R-NH3)2 (FA) layer. n- 1Pb n I 3n+1 Thin film, hole transport layer and metal electrode.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] This invention proposes a method for controlling the dimensionality of perovskite thin films prepared by three-source co-evaporation and its application. The method targets large cations based on ammonium salt molecules PMAI and PEAI containing benzene rings, or chain-like ammonium salt molecules BAI, and is used to prepare (R-NH3)2(FA) films by three-source co-evaporation. n-1 Pb n I 3n+1 Post-annealing in air helps improve the quality of perovskite thin films and provides the necessary energy for forming structures with different dimensions. The dimensional control of perovskite thin films can be achieved simply by adjusting the post-annealing temperature. This invention does not require fine control of process parameters such as evaporation rate and chamber pressure during the gas-phase co-evaporation process, making it simple to operate and highly repeatable. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the process for controlling the dimensions of the three-source co-evaporation perovskite thin film in Embodiment 1 of the present invention;

[0024] Figure 2 This is a schematic diagram of the structure of the perovskite solar cell prepared in Example 1 of the present invention;

[0025] Figure 3 (PMA)2(FA) prepared in Example 1 of this invention n-1 Pb n I 3n+1 PL (photoluminescence) spectroscopy test results of perovskite thin films;

[0026] Figure 4 Statistical analysis of the photoelectric conversion efficiency parameters of the perovskite solar cell prepared in Example 1 of the present invention;

[0027] Figure 5 (PEA)2(FA) prepared in Example 2 of this invention n-1 Pb n I 3n+1 PL spectral test results of perovskite thin films;

[0028] Figure 6 Statistical analysis of the photoelectric conversion efficiency parameters of the perovskite solar cell prepared in Example 2 of the present invention;

[0029] Figure 7 (BA)2(FA) prepared in Example 3 of this invention n-1 Pb n I 3n+1 PL spectral test results of perovskite thin films;

[0030] Figure 8 The photoelectric conversion efficiency parameters of the perovskite solar cell prepared in Example 3 of this invention are statistically analyzed. Detailed Implementation

[0031] To further understand the present invention, preferred embodiments are described below with reference to examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims. All raw materials used in the present invention are not particularly limited in their source; they can be purchased commercially or prepared using conventional methods well known to those skilled in the art.

[0032] Example 1

[0033] This embodiment provides a method for controlling the dimensionality of three-source co-evaporated perovskite thin films, the process of which is as follows: Figure 1 As shown, it includes the following steps:

[0034] Step A1. Deposit SnO2 onto an FTO (conductive indium tin oxide) substrate by spin coating and anneal in air at a temperature of 150°C for 30 minutes.

[0035] Step A2. Prepare (PMA)2(FA) on the SnO2 substrate obtained in step A1 by co-evaporation of PMAI, PbI2 and FAI from three sources. n-1 Pb n I 3n+1 Perovskite thin films, n>1, specifically:

[0036] Step A2.1. In the glove box, use an electronic balance to weigh 0.5g PMAI, 1g PbI2 and 1g FAI, and place them in their respective crucibles;

[0037] Step A2.2. Place the SnO2 substrate obtained in step A1 on the sample holder of the vapor deposition apparatus;

[0038] Step A2.3. Close the vapor deposition chamber door, turn on the mechanical pump and molecular pump to evacuate to 10. -4 Pa;

[0039] Step A2.4. Turn on the heating power of the PbI2 evaporation source and adjust the evaporation temperature so that the evaporation rate of PbI2 is [value missing].

[0040] Step A2.5. Turn on the FAI evaporation source and heat to 135.5℃. The FAI evaporation rate is approximately... The gas pressure in the vapor deposition apparatus chamber is maintained at 2.0 × 10⁻⁶. -3 Pa;

[0041] Step A2.6. Turn on the PMAI evaporator and heat to 80-90°C (87°C in this example). The evaporation rate is approximately...

[0042] Step A2.7. When the deposition thickness reaches 520 nm, turn off the substrate baffle and the evaporation source heating power to end the evaporation process and obtain (PMA)2(FA). n-1 Pb n I 3n+1 Perovskite thin films;

[0043] Step A3. After deposition in step A2, the deposited film is removed and annealed in air. The annealing temperatures are set to 40℃, 60℃, 80℃, 100℃, 120℃ and 150℃, respectively, and the annealing time is 20 min for each temperature, to obtain (PMA)2(FA) after different annealing temperatures. n-1 Pb n I 3n+1 Perovskite thin films.

[0044] In this embodiment, (PMA)2(FA) that has not undergone step A3 annealing is used. n-1 Pb n I 3n+1 Perovskite thin film (denoted as control), and (PMA)2(FA) after annealing at 40℃, 60℃, 80℃, 100℃, 120℃ and 150℃ respectively. n- 1Pb n I 3n+1 Optical analysis of perovskite thin films yielded results such as... Figure 3 The PL spectrum shown indicates that: (PMA)₂(FA) n-1 Pb n I 3n+1 The three-dimensional perovskite film contains two-dimensional perovskite components (n=2) after unannealing and after annealing at 40℃ and 60℃ respectively. After annealing at 80℃, 100℃, 120℃ and 150℃ respectively, the perovskite film contains only three-dimensional perovskite components. At the annealing temperature of 150℃, the perovskite film has the most uniform film composition (smallest half-width at half-maximum) and the longest carrier lifetime.

[0045] This embodiment also fabricates a perovskite solar cell, with the structure as follows: Figure 2 As shown, from bottom to top, the layers are: FTO transparent glass, electron transport layer SnO2, and annealed (PMA)2 (FA). n-1 Pb n I 3n+1 Perovskite thin film, hole transport layer Spiro-OMeTAD and Au metal electrode.

[0046] The preparation method includes the following steps:

[0047] Step B1. The FTO conductive glass substrate is ultrasonically cleaned with deionized water, acetone and anhydrous ethanol for 15 min respectively, and then treated with ultraviolet ozone for 15 min to remove organic residues.

[0048] Step B2. Prepare the electron transport layer SnO2 and the annealed (PMA)2(FA) using the methods in steps A1 to A3. n-1 Pbn I 3n+1 Perovskite thin films;

[0049] Step B3. The hole transport layer Spiro-OMeTAD was dissolved in chlorobenzene (73.4 mg / ml), and 28.8 μL of tert-butylpyridine (tBP) and 17.5 μL of lithium salt (Li-tFSI) were added. The solution was then spin-coated onto the annealed (PMA)2(FA) at a speed of 3000 rpm / min. n-1 Pb n I 3n+1 On perovskite thin films;

[0050] Step B4. By evaporating gold at a density of 120 nm onto the hole transport layer prepared in step B3 as an electrode, the desired perovskite solar cell can be obtained.

[0051] The photoelectric conversion efficiency of the perovskite solar cell obtained in this embodiment was tested. Specifically, the active area of ​​the perovskite solar cell used was 0.0491 cm². 2 It was tested under standard simulated sunlight AM1.5, 30% air humidity, and 25°C conditions, compared with (PMA)2(FA) that had not undergone step A3 annealing. n-1 Pb n I 3n+1 Perovskite thin film (denoted as control), and (PMA)2(FA) after annealing at 40℃, 60℃, 80℃, 100℃, 120℃ and 150℃ respectively. n- 1Pb n I 3n+1 The photoelectric conversion efficiency data of perovskite thin films for perovskite solar cells are as follows: Figure 4 As shown, it can be seen that: (PMA)2(FA) n-1 Pb n I 3n+1 Without annealing, the photoelectric conversion efficiency of perovskite solar cells is only 2.03%. As the annealing temperature increases, the photoelectric conversion efficiency of perovskite solar cells gradually increases, reaching a maximum of 15.45% at 150℃. This indicates that the efficiency of (PMA)2(FA) prepared by three-source co-evaporation based on ammonium salt molecules containing benzene rings (PMAI) is significantly improved. n-1 Pb n I 3n+1 Post-annealing of perovskite thin films helps improve film quality and the photoelectric conversion efficiency of perovskite solar cells.

[0052] Example 2

[0053] This embodiment provides a method for controlling the dimensionality of three-source co-evaporated perovskite thin films, including the following steps:

[0054] Step A1. Deposit SnO2 onto the FTO substrate by spin coating and anneal in air at a temperature of 150°C for 30 min.

[0055] Step A2. Prepare (PEA)2(FA) on the SnO2 substrate obtained in step A1 by three-source co-evaporation of PEAI, PbI2 and FAI. n-1 Pb n I 3n+1 Perovskite thin films, n>1, specifically:

[0056] Step A2.1. In the glove box, use an electronic balance to weigh 0.5g PEAI, 1g PbI2 and 1g FAI and place them in their respective crucibles;

[0057] Step A2.2. Place the SnO2 substrate obtained in step A1 on the sample holder of the vapor deposition apparatus;

[0058] Step A2.3. Close the vapor deposition chamber door, turn on the mechanical pump and molecular pump to evacuate to 10. -4 Pa;

[0059] Step A2.4. Turn on the heating power of the PbI2 evaporation source and adjust the evaporation temperature so that the evaporation rate of PbI2 is [value missing].

[0060] Step A2.5. Turn on the FAI evaporation source and heat to 135.5℃. The FAI evaporation rate is approximately... The gas pressure in the vapor deposition apparatus chamber is maintained at 2.0 × 10⁻⁶. -3 Pa;

[0061] Step A2.6. Turn on the PEAI evaporator and heat to 100-110℃ (105℃ in this example). The evaporation rate is approximately...

[0062] Step A2.7. When the deposition thickness reaches 520 nm, turn off the substrate baffle and the evaporation source heating power to end the evaporation process and obtain (PEA)2(FA). n-1 Pb n I 3n+1 Perovskite thin films;

[0063] Step A3. After deposition in step A2, the deposited film is removed and annealed in air. The annealing temperatures are set to 40℃, 60℃, 80℃, 100℃, 120℃ and 150℃, respectively, and the annealing time is 20 min for each temperature, to obtain (PEA)2(FA) after different annealing temperatures. n-1 Pb n I 3n+1 Perovskite thin films.

[0064] In this embodiment, (PEA)2(FA) is annealed without undergoing step A3. n-1 Pb n I 3n+1 Perovskite thin film (denoted as control), and (PEA)2(FA) after annealing at 40℃, 60℃, 80℃, 100℃, 120℃ and 150℃ respectively. n- 1Pb n I 3n+1 Optical analysis of perovskite thin films yielded results such as... Figure 5 The PL spectrum shown indicates that: (PEA)₂(FA) n-1 Pb n I 3n+1 The three-dimensional perovskite film contains two-dimensional perovskite components (n=2) after unannealed treatment and after low-temperature annealing treatment at 40℃ and 60℃ respectively. After annealing treatment at 80℃, 100℃, 120℃ and 150℃ respectively, the perovskite film contains only three-dimensional perovskite components. At the annealing temperature of 150℃, the perovskite film has the most uniform film composition (smallest half-width at half-maximum) and the longest carrier lifetime.

[0065] This embodiment also fabricates a perovskite solar cell, which, from bottom to top, consists of: FTO transparent glass, an electron transport layer SnO2, and annealed (PEA)2(FA). n-1 Pb n I 3n+1 Perovskite thin film, hole transport layer Spiro-OMeTAD, and Au metal electrode. The preparation method differs from Example 1 only in that step A2 in step B2 is changed to prepare (PEA)2(FA). n-1 Pb n I 3n+1 The steps for perovskite thin films are the same; the remaining steps are identical.

[0066] The photoelectric conversion efficiency of the perovskite solar cell obtained in this embodiment was tested. Specifically, the active area of ​​the perovskite solar cell used was 0.0491 cm². 2 It was tested under standard simulated sunlight AM1.5, 30% air humidity, and 25°C conditions, compared with (PEA)2(FA) that had not undergone step A3 annealing. n-1 Pb n I 3n+1 Perovskite thin film (denoted as control), and (PEA)2(FA) after annealing at 40℃, 60℃, 80℃, 100℃, 120℃ and 150℃ respectively. n- 1Pb nI 3n+1 The photoelectric conversion efficiency data of perovskite thin films for perovskite solar cells are as follows: Figure 6 As shown, it can be seen that: (PEA)2(FA) n-1 Pb n I 3n+1 Without annealing, the photoelectric conversion efficiency of perovskite solar cells is only 3.79%. As the annealing temperature increases, the photoelectric conversion efficiency of perovskite solar cells gradually increases, reaching a maximum of 10.17% at 150℃. This indicates that the efficiency of (PEA)2(FA) prepared by three-source co-evaporation based on ammonium salt molecules containing benzene rings (PEAI) is significantly improved. n-1 Pb n I 3n+1 Post-annealing of perovskite thin films helps improve film quality and the photoelectric conversion efficiency of perovskite solar cells.

[0067] Example 3

[0068] This embodiment provides a method for controlling the dimensionality of three-source co-evaporated perovskite thin films, including the following steps:

[0069] Step A1. Deposit SnO2 onto the FTO substrate by spin coating and anneal in air at a temperature of 150°C for 30 min.

[0070] Step A2. Prepare (BA)2(FA) on the SnO2 substrate obtained in step A1 by three-source co-evaporation of BAI, PbI2 and FAI. n-1 Pb n I 3n+1 Perovskite thin films, n>1, specifically:

[0071] Step A2.1. In the glove box, use an electronic balance to weigh 0.5g BAI, 1g PbI2 and 1g FAI and place them in their respective crucibles;

[0072] Step A2.2. Place the SnO2 substrate obtained in step A1 on the sample holder of the vapor deposition apparatus;

[0073] Step A2.3. Close the vapor deposition chamber door, turn on the mechanical pump and molecular pump to evacuate to 10. -4 Pa;

[0074] Step A2.4. Turn on the heating power of the PbI2 evaporation source and adjust the evaporation temperature so that the evaporation rate of PbI2 is [value missing].

[0075] Step A2.5. Turn on the FAI evaporation source and heat to 135.5℃. The FAI evaporation rate is approximately... The gas pressure in the vapor deposition apparatus chamber is maintained at 2.0 × 10⁻⁶.-3 Pa;

[0076] Step A2.6. Turn on the BAI evaporator and heat to 80-85℃ (83℃ in this example). The evaporation rate is approximately...

[0077] Step A2.7. When the deposition thickness reaches 520 nm, turn off the substrate baffle and the evaporation source heating power to end the evaporation process and obtain (BA)2(FA). n-1 Pb n I 3n+1 Perovskite thin films;

[0078] Step A3. After deposition in step A2, the deposited film is removed and annealed in air. The annealing temperatures are set to 40℃, 60℃, 80℃, 100℃, 120℃ and 150℃, respectively, and the annealing time is 20 min for each temperature, to obtain (BA)2(FA) after different annealing temperatures. n-1 Pb n I 3n+1 Perovskite thin films.

[0079] In this embodiment, (BA)2(FA) is annealed without undergoing step A3. n-1 Pb n I 3n+1 Perovskite thin film (denoted as control), and (BA)2(FA) after annealing at 40℃, 60℃, 80℃, 100℃, 120℃ and 150℃ respectively. n- 1Pb n I 3n+1 Optical analysis of perovskite thin films yielded results such as... Figure 7 The PL spectrum shown indicates that: (BA)2(FA) n-1 Pb n I 3n+1 After annealing at 60℃, 80℃, 100℃ and 120℃, the three-dimensional perovskite film contains two-dimensional perovskite components (n=2). However, without annealing, and after annealing at 40℃ and 150℃, the perovskite film contains only three-dimensional perovskite components. At the annealing temperature of 150℃, the perovskite film has the most uniform film composition (smallest half-width at half-maximum) and the longest carrier lifetime.

[0080] This embodiment also fabricates a perovskite solar cell, which, from bottom to top, consists of: FTO transparent glass, an electron transport layer SnO2, and annealed (BA)2(FA). n-1 Pb n I 3n+1Perovskite thin film, hole transport layer Spiro-OMeTAD, and Au metal electrode. The preparation method differs from Example 1 only in that step A2 in step B2 is changed to prepare (BA)2(FA). n-1 Pb n I 3n+1 The steps for perovskite thin films are the same; the remaining steps are identical.

[0081] The photoelectric conversion efficiency of the perovskite solar cell obtained in this embodiment was tested. Specifically, the active area of ​​the perovskite solar cell used was 0.0491 cm². 2 It was tested under standard simulated sunlight AM1.5, 30% air humidity, and 25°C conditions, compared with (BA)2(FA) that had not undergone step A3 annealing. n-1 Pb n I 3n+1 Perovskite thin film (denoted as control), and (BA)2(FA) after annealing at 40℃, 60℃, 80℃, 100℃, 120℃ and 150℃ respectively. n- 1Pb n I 3n+1 The photoelectric conversion efficiency data of perovskite thin films for perovskite solar cells are as follows: Figure 8 As shown, it can be seen that: (BA)2(FA) n-1 Pb n I 3n+1 The perovskite solar cell exhibits a photoelectric conversion efficiency of 9.59% without annealing, while the annealed perovskite solar cell reaches a peak of 10.21% at 40°C. This indicates that the (BA)2(FA) obtained by three-source co-evaporation based on chain-like ammonium salt molecules BAI is highly efficient. n-1 Pb n I 3n+1 For perovskite thin films, proper post-annealing treatment can help improve film quality and the photoelectric conversion efficiency of perovskite solar cells.

[0082] The above embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, is within the scope of protection of the present invention.

Claims

1. A method for controlling the dimensionality of a three-source co-evaporated perovskite thin film, characterized in that, (R-NH3)2(FA) was deposited on a substrate by co-evaporation of the large cations R-NH3I, PbI2, and FAI from three sources. n-1 Pb n I 3n+1 Perovskite thin films, n>1, were then annealed in air for 20 min. The (R-NH3)2(FA) content was adjusted by changing the annealing temperature. n-1 Pb n I 3n+1 The dimensions of the perovskite thin film; wherein, the R-NH3I is specifically PMAI, PEAI, or BAI; When R-NH3I is PMAI, the vapor-deposited (PMA)2(FA) n-1 Pb n I 3n+1 After annealing at temperatures below 80°C, the perovskite film is composed of a mixed phase of two-dimensional and three-dimensional perovskite; after annealing at temperatures above or equal to 80°C, its composition is entirely three-dimensional perovskite. When R-NH3I is PEAI, the vapor-deposited (PEA)2(FA) n-1 Pb n I 3n+1 After annealing at temperatures below 80°C, the perovskite film is composed of a mixed phase of two-dimensional and three-dimensional perovskite; after annealing at temperatures above or equal to 80°C, its composition is entirely three-dimensional perovskite. When R-NH3I is BAI, the vapor-deposited (BA)2(FA) n-1 Pb n I 3n+1 After annealing at temperatures greater than 40°C and less than 150°C, the perovskite film is composed of a mixed phase of two-dimensional and three-dimensional perovskite; after annealing at temperatures less than or equal to 40°C or greater than or equal to 150°C, its composition is entirely three-dimensional perovskite.

2. The method for controlling the dimensionality of three-source co-evaporated perovskite thin films according to claim 1, characterized in that, When three sources are used for co-evaporation, the mass ratio of the evaporation sources R-NH3I, PbI2 and FAI is (0.1~0.5):1:

1.

3. The method for controlling the dimensionality of three-source co-evaporated perovskite thin films according to claim 1, characterized in that, The evaporation rate of PbI2 is 1.45~1.55 Å / s, and the evaporation rate of FAI is 1.17~3.05 Å / s.

4. The method for controlling the dimensionality of three-source co-evaporated perovskite thin films according to claim 3, characterized in that, The evaporation rate of PMAI is 0.38~0.77 Å / S, the evaporation rate of PEAI is 0.15~0.35 Å / S, and the evaporation rate of BAI is 0.31~0.59 Å / S.

5. The method for controlling the dimensionality of three-source co-evaporated perovskite thin films according to claim 1, characterized in that, (R-NH3)2(FA) obtained by vapor deposition n-1 Pb n I 3n+1 The thickness of the perovskite film is 500~600 nm.

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