Superhalogen Boron Tetrafluoride Surface Modification Reduces the Formation of Organic Cation Vacancies on the Surface of Halide Perovskite Films

This is the authors' abstract. We don't add key points for this paper.

It is generally known that lead halide perovskite films used in solar cell devices inevitably introduce defects during solution-based growth at near room temperature. In all defects, the halide anion and organic cation vacancies are ubiquitous, facilitating ion diffusion and leading to the decomposition of thin films at the surface and grain boundaries. Studies have shown that fluoride can be introduced into the film and the strong electronegativity of fluorine can be used to passivate the point vacancies. In this study, the first-principles method based on density functional theory is used to investigate the introduction of superhalogen BF4 anions on the surface of the FAPbI3 perovskite film, which is more electronegative than fluoride. By using the strong electronegativity of BF4 to strengthen the chemical bond with the Pb atom and combine with organic cations, it can effectively passivate the I atom vacancy and improve the formation energy of the formamidinium (FA) vacancy, thereby inhibiting the formation of FA vacancies. This approach provides a feasible way to prepare high-stability perovskite solar cells.