Method for improving photoelectric property and stability of perovskite solar cell

Abstract

The invention discloses a method for improving photoelectric performance and stability of a perovskite solar cell, and belongs to the technical field of preparation of perovskite solar cells. According to the technical scheme, 4-fluorophthalic anhydride is introduced into a perovskite light absorption layer of the perovskite solar cell. 4-fluorophthalic anhydride is used as a passivating agent, so that the adverse effect of surface defects of the perovskite thin film can be effectively inhibited, the performance of the perovskite solar cell is improved, and the service life of the cell in a humid environment is prolonged. The method is simple, effective and wide in application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium ore solar cell preparation, and specifically relates to a method for improving the photoelectric performance and stability of a perovskite solar cell. Background Art

[0002] As one of the new photovoltaic technologies, perovskite solar cells have many advantages, such as large light absorption coefficient, small exciton binding energy, long carrier diffusion range, adjustable band gap and simple manufacturing process. Under the extensive research of researchers, its photoelectric conversion efficiency has reached 26.7%, showing a very considerable application potential. In the future, it is very likely to replace single-crystal silicon solar cells and move towards a new stage of large-scale commercial production, becoming the next generation of innovative and high-efficiency thin-film solar cells, emerging and playing a key role in the field of renewable energy. However, due to the sensitive properties of perovskite materials to moisture and oxygen, the stability of perovskite solar cells has always been a problem that hinders its development and commercialization. In addition, there are a large number of defects on the surface and grain boundaries of perovskite films, which leads to non-radiative conformity of photogenerated carriers and reduces the performance of perovskite solar cells. Surface passivation can suppress the adverse effects of defects and improve the performance of perovskite solar cells. Defect passivation can not only reduce carrier recombination, thereby improving the optoelectronic performance of the device, but also effectively prevent the erosion of perovskite materials by environmental factors such as moisture and oxygen, thereby extending the service life of the battery in a humid environment. The reason why 4-fluorophthalic anhydride (4-FA) can be used as a passivating agent is that it has two carbonyl groups (-C=O) that can provide lone electron pairs. In addition, the F atom on the benzene ring has strong electronegativity and easily forms a hydrogen bond with the H on -NH2. At present, there are no patent reports on the application of 4-fluorophthalic anhydride in perovskite solar cells. Summary of the invention

[0003] The purpose of the present invention is to provide a method for improving the photoelectric performance and stability of perovskite solar cells. By introducing 4-fluorophthalic anhydride into the perovskite light-absorbing layer of the perovskite solar cell, the adverse effects of surface defects of the perovskite film can be effectively suppressed, the performance of the perovskite solar cell can be improved, and the service life of the battery in a humid environment can be extended.

[0004] To achieve the above object, the present invention adopts the following technical solutions: A method for improving the photoelectric performance and stability of perovskite solar cells: introducing 4-fluorophthalic anhydride into the perovskite light-absorbing layer of the perovskite solar cell.

[0005] 4-Fluorophthalic anhydride is prepared into a 0.01-0.1 mg / mL solution, and coated on the perovskite film by spin coating, dipping or drop coating. The solvent is at least one of chlorobenzene, toluene and ethyl acetate.

[0006] The beneficial effect of the present invention is that 4-FA is introduced into the perovskite solar cell, and the -C=O in 4-FA has a charge-rich characteristic, which can capture and neutralize the uncoordinated Pb in the perovskite. 2+ At the same time, due to the formation of hydrogen bonds between the -F in 4-FA and the perovskite precursor monomer, the crystallization process of the perovskite film is optimized. Therefore, through the combined effect of defect passivation and crystallization improvement, the highest photoelectric conversion efficiency of the perovskite solar cell reaches 23.97%. After being placed in the air for 60 days, the perovskite solar cell based on 4-FA can still maintain 87% of the initial efficiency, which highlights the great potential of 4-FA as a defect passivation additive in the development of high-performance and stable perovskite solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 The diagram is a schematic diagram of the molecular structure of 4-FA and its introduction process and mechanism of action; Figure 2 X-ray diffraction patterns of perovskite films treated with different concentrations of 4-FA; Figure 3 SEM images of perovskite films before and after 4-FA modification; Figure 4 X-ray photoelectron spectra of perovskite films before and after 4-FA modification; Figure 5 FAI, 4-FA, and a mixture of FAI and 4-FA 1 HNMR spectrum; Figure 6 Photovoltaic performance of perovskite solar cells without 4-FA modification and with different concentrations of 4-FA modification; Figure 7 The stability of 4-FA-modified perovskite solar cells under continuous storage conditions. DETAILED DESCRIPTION

[0008] In order to make the contents of the present invention easier to understand, the technical solution of the present invention is further described below in conjunction with specific implementation methods, but the present invention is not limited thereto.

[0009] Example 1 In a glove box, 4-FA was dissolved in an anti-solvent and evenly added to the perovskite light-absorbing layer by spin coating. The specific steps were as follows: 3 mg of 4-FA was weighed, dissolved in 300 mL of chlorobenzene, toluene, and ethyl acetate, stirred evenly, and filtered to prepare a solution with a concentration of 0.01 mg / mL. The solution was then added to the perovskite wet film at a speed of 5000 rpm, and then annealed on a hot plate at 120 °C. The transport layer and electrodes were further deposited on the perovskite absorption layer to complete the preparation of the perovskite solar cell.

[0010] Example 2 In a glove box, 4-FA was dissolved in an anti-solvent and evenly added to the perovskite light-absorbing layer by spin coating. The specific steps were as follows: 3 mg of 4-FA was weighed, dissolved in 60 mL of chlorobenzene, toluene, and ethyl acetate, stirred evenly, and filtered to prepare a solution with a concentration of 0.05 mg / mL. The solution was then added to the perovskite wet film at a speed of 5000 rpm, and then annealed on a hot plate at 120 °C. The transport layer and electrodes were further deposited on the perovskite absorption layer to complete the preparation of the perovskite solar cell.

[0011] Example 3 In a glove box, 4-FA was dissolved in an anti-solvent and evenly added to the perovskite light-absorbing layer by spin coating. The specific steps were as follows: 3 mg of 4-FA was weighed, dissolved in 30 mL of chlorobenzene, toluene, and ethyl acetate, stirred evenly, and filtered to prepare a solution with a concentration of 0.1 mg / mL. The solution was then added to the perovskite wet film at a speed of 5000 rpm, and then annealed on a hot plate at 120 °C. The transport layer and electrodes were further deposited on the perovskite absorption layer to complete the preparation of the perovskite solar cell.

[0012] Example 4 In a glove box, 4-FA monomer was dissolved in an anti-solvent and added dropwise to the perovskite light-absorbing layer after spin coating by a drop coating method. The specific steps were as follows: 3 mg of 4-FA was weighed and dissolved in 300 mL of chlorobenzene, toluene and ethyl acetate. The solution was stirred evenly and filtered to prepare a solution with a concentration of 0.01 mg / mL. The solution was then slowly and evenly added to the perovskite wet film that had been spin-coated but not annealed. The excess solution was then removed and annealed on a hot plate at 120 °C. The transport layer and electrodes were then deposited on the perovskite absorption layer to complete the preparation of the perovskite solar cell.

[0013] Example 5 In a glove box, 4-FA monomer was dissolved in an anti-solvent and added to the perovskite light-absorbing layer after spin coating by immersion method. The specific steps were as follows: 3 mg of 4-FA was weighed and dissolved in 300 mL of chlorobenzene, toluene and ethyl acetate. The mixture was stirred evenly and filtered to prepare a solution with a concentration of 0.01 mg / mL. The spin-coated but unannealed perovskite wet film was then slowly immersed in the solution for 2 seconds and then quickly taken out to remove excess solution at the edge. The film was then annealed on a hot plate at 120 °C. The transport layer and electrodes were further deposited on the perovskite absorption layer to complete the preparation of the perovskite solar cell.

[0014] Photoelectric performance test: Test the photoelectric conversion performance under the AM 1.5G standard solar simulator; Figure 1 The molecular structure of 4-FA and its introduction process and mechanism of action are shown in Figure 2. The electronegativity of the 4-FA molecule is mainly concentrated on the anhydride group, and the carbonyl group (-C=O) can be an uncoordinated Pb 2+ Providing lone electron pairs to form coordination bonds, thus passivating this major defect of perovskite. In addition, the F atom on the benzene ring can form a hydrogen bond with the H atom on -NH2 in FAI, thereby slowing down the crystallization speed of perovskite and improving the crystallization quality of perovskite film. Figure 2 XRD spectra of the blank group and the perovskite film treated with 4-FA, where the addition amount of 4-FA was 0.01 mg mL -1 , 0.05 mg mL -1 and 0.1 mg mL -1 . The diffraction peaks of the XRD spectra of each perovskite film are located in the same position, indicating that the introduction of 4-FA molecules will not change the crystal structure of the perovskite. Compared with the untreated perovskite film, the perovskite film treated with 4-FA shows a higher diffraction peak intensity, which indicates that the crystallinity of the film is improved after 4-FA treatment. In addition, both groups of films show the diffraction peak of PbI2 at 12.6°, but the corresponding peak intensity of the 4-FA group is slightly reduced, indicating that 4-FA molecules can promote the conversion of undesirable PbI2 into favorable perovskite crystals. Figure 3 This is a scanning electron microscope (SEM) image of the perovskite film before and after treatment with 4-FA. It shows that after 4-FA modification, the grain size of the perovskite is significantly increased, which leads to a reduction in grain boundaries and voids, which is beneficial to improving the performance of perovskite solar cells. Figure 4 The XPS spectra of the perovskite films with and without 4-FA modification are shown in Figure 2. For the control film, the characteristic peak positions of Pb are 143.6 and 138.8 eV, corresponding to Pb 4f 5 / 2 and 4f 7 / 2 After 4-FA modification, Pb 4f 5 / 2 and 4f7 / 2 The peak positions are 142.8 and 137.9 eV, respectively, and both have moved toward the direction of low binding energy. This indicates that the electron cloud density around Pb has increased, which can be attributed to the Lewis acid-base coordination between O and Pb in -C=O, and the lone pair of electrons O is transferred to Pb in the perovskite. 2+ The formation of coordination bonds on the perovskite passivates this defect. Figure 5 They are FAI, 4-FA and a mixture of FAI and 4-FA. 1 HNMR spectrum. Among them, the characteristic peak position of FAI is a single peak at 8.83 ppm. After adding 4-FA molecules, the characteristic peak splits into two characteristic peaks at 9.00 ppm and 8.65 ppm, indicating that there is interaction between FAI and 4-FA molecules and hydrogen bonds are formed, and the chemical environment of H has changed. In addition, it can be seen that the characteristic peak position of 4-FA molecules has not changed, indicating that it is FA in FAI that forms hydrogen bonds with F. + . Figure 6 The photoelectric performance of perovskite solar cells without 4-FA modification and with different concentrations of 4-FA modification is shown in Figure 2. The highest efficiency of the device modified with 4-FA is 23.97%. Figure 7 The PCE decay curves of the two groups of devices under continuous storage conditions. After the devices were stored in air (15±5% RH, 25 ℃) for 60 days, the 4-FA-based devices still maintained 86.8% of the initial PCE. However, the control group devices dropped to 69.1% of the initial PCE. Therefore, 4-FA modification is a simple, feasible and efficient strategy to improve the stability of perovskite solar cells.

[0015] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for improving the photoelectric performance and stability of perovskite solar cells, characterized in that: 4-Fluorophthalic anhydride is introduced into the perovskite light-absorbing layer of perovskite solar cells.

2. The method according to claim 1, characterized in that: 4-Fluorophthalic anhydride is prepared into a 0.01-0.1 mg / mL solution and coated on the perovskite film by spin coating, dipping or drop coating.

3. The method according to claim 2, characterized in that: The solvent is at least one of chlorobenzene, toluene and ethyl acetate.

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