High-quality CsPbBr3 films prepared by introducing methylammonium iodide into PbBr2 precursor for efficient perovskite solar cells

CsPbBr 3 perovskite solar cells (PSCs) have attracted a lot of attention due to their excellent long-term stability and easy fabrication in humid air. The preparation of the light-absorbing layer is crucial for achieving high efficiency in CsPbBr 3 perovskite solar cells. In this study, methylammonium iodide (CH 3 NH 3 I, MAI) was introduced into the PbBr 2 precursor solution to improve the quality of perovskite films and the photovoltaic performance of PSCs. The spin-coating method was employed to prepare CsPbBr 3 films in ambient air. Firstly, a layer of PbBr 2 film was spin-coated, followed by two spin-coatings of CsBr solution on top of it. By adjusting the content of MAI additives, a PbBr 2 film with a microporous structure was obtained. These porous structures acted as channels for CsBr molecules, enabling them to react fully with PbBr 2 and more favorable for the crystallization of CsPbBr 3 . As a result, we achieved the high-purity, high-crystallinity, and continuous CsPbBr 3 films. Furthermore, we utilized CsPbBr 3 films as the light-absorbing layer in PSCs with a structure of FTO/c-TiO 2 /m-TiO 2 /CsPbBr 3 /carbon, a champion power conversion efficiency of 8.02% was achieved, and the unencapsulated device showed excellent long-term stability.