2D BA2PbI4 Regulating PbI2 Crystallization to Induce Perovskite Growth for Efficient Solar Cells.

Abstract

Using seeds to control the crystallization of perovskite film is an effective strategy for achieving high-efficiency perovskite solar cells (PSCs). Owing to their excellent environmental stability brought by their long alkyl chain, n-butylammonium (BA) cations are widely used for fabricating efficient and stable PSCs. However, BA-based 2D perovskite is seldom been investigated as a seed. Here, BA2PbI4 is employed to regulate the crystallization of PbI2, acting as nucleation centers. As a result, porous PbI2 film with high crystallinity is obtained, which allows the realization of perovskite film with preferential crystal orientations of (001) and large grain size of over 2µm. The corresponding PSC achieves a high power conversion efficiency (PCE) of 24.30% and exhibits satisfactory stability, retaining 91.70% of the initial PCE after 300h of thermal aging at 85°C.