Highly efficient and stable inorganic CsPbBr3 perovskite solar cells via vacuum co-evaporation

High power conversion efficiency (PCE) and good long-term stability are everlasting pursuit for perovskite solar cells. We present here CsPbBr3 perovskite film deposited by vacuum co-evaporation of CsBr and PbBr2. By optimizing evaporation rate ratio of the two precursor and annealing temperature, perovskite films with large grain and high crystallinity are obtained. Furthermore, by regulating spinning speed of TiO2 precursor solution and thickness of CsPbBr3 film, a best PCE of 9.43% is recorded under 100 mW cm-2 illumination, providing a significant enhancement in contrast with 6.26% of device based on spin-coating method. Additionally, the PCE of resulting perovskite solar cell without encapsulation remains at 96% of initial value after storing for 480 h under humidity of 40% in air. Our findings in this work deliver an effective strategy to fabricate high-performance inorganic perovskite solar cells.