Solvent evaporation induced preferential crystal orientation BiI3 films for the high efficiency MA3Bi2I9 perovskite solar cells

Abstract

In this paper, we develop a solvent evaporation induced method and demonstrate that it is effective in suppressing the growth of the BiI 3 (003) crystal plane and favoring the growth of BiI 3 (113) and (300) crystal planes. By using the as-prepared BiI 3 films, we successfully fabricated BiI 3 and MA 3 Bi 2 I 9 (MBI) coexisting films with weakened (006) crystal planes, which are generally oriented parallel to the substrate and prohibit carrier transport. Additionally, compared with MBI films prepared from controlled BiI 3 films, the resultant BiI 3 -MBI film is more suitable for fabricating efficient and stable photovoltaic devices. The best performing photovoltaic device exhibits a power conversion efficiency of 1.53%. This work provides a new strategy for realizing high-efficiency Bi-based perovskite solar cells. The BiI 3 and MBI co-existing films have been successfully fabricated from BiI 3 films with the weakened (003) preferred orientation by the DMF solvent evaporation induced method. The device performance could be improved by regulating the ratio of BiI 3 to MBI in the films. • The preferential crystal orientation of BiI 3 films with (113) and (300) crystal plane was obtained by the DMF solvent evaporation induced method. • The growth of the BiI 3 (003) crystal plane was restricted, which also effectively limited the growth of the MBI (006) crystal plane. • BiI 3 and MBI co-existing perovskite solar cells were fabricated by low pressure vapor assisted solution process.