Prepared high quality Cs _x FA _{1 − x} PbI ₃ based perovskite solar cells with template‐assisted technique

Abstract

The CsxFA1−xPbI3 perovskites are promising materials for photovoltaic applications owing to their high absorption coefficient and stability. However, the CsxFA1−xPbI3 films contain a high percentage of FA+ suffer from split phase and high trap states, leading to inferior photovoltaic performance. Hence, a template-assisted technique basing on two-stage intramolecular exchanges was developed to suppress phase separation as well as get desirable high quality CsxFA1−xPbI3 perovskite film. The as-prepared colloidal CsI-PbI2 film is treated with FAI solution before annealing. The obtained CsxFA1−xPbI3 perovskite thin layer displays a superb absorption edge beyond 830 nm and highly uniform enlarged grains with reduced grain boundaries or defects. Meanwhile, the improved morphology attributes to substantially increased photon-induced electron-hole pairs and corresponding collection efficiency which was testified by the external quantum efficiency measurements. The perovskite solar cells fabricated by this method presented power conversion efficiency of 18.5%.