The potassium acetate additive enhances the stability of the FA0.75MA0.25SnI3 precursor solution and the performance of corresponding perovskite solar cells

Although Sn-based perovskite solar cells (PSCs) have achieved excellent conversion efficiency, the issue of easy oxidation of Sn2+ still needs to be addressed. This paper believes that the antioxidant ability of PSCs can be improved starting from the precursor solutions. In this work, potassium acetate (KAc) is first added to FA0.75MA0.25SnI3 precursor solution to suppress the oxidation of Sn2+ and to prepare a high-quality KAc-FA0.75MA0.25SnI3 composite film. The KAc-FA0.75MA0.25SnI3 film has better crystallinity and optical absorption, reduced defect density and unnecessary non-radiative recombination while suppressing Sn2+ oxidation. Finally, the PSCs based on KAc-FA0.75MA0.25SnI3 film achieved an excellent power conversion efficiency of 9.62% and a long-term stability of over 850 h to retain 80% of its initial efficiency.