Efficient planar CsPbBr3 perovskite solar cells by dual-source vacuum evaporation

Organic inorganic hybrid halide perovskites materials have inspired enormous interest in the photovoltaic research community; however, they are currently plagued by insufficient environmental stability. To overcome this problem, all-inorganic halide perovskites have been developed and exhibit significantly improved stability. Here, vacuum thermal evaporation deposition of CsPbBr3 perovskite films is developed by dual-source coevaporation of CsBr and PbBr2 precursors. The evaporation rate ratio of CsBr to PbBr2 determines the stoichiometry of the deposited CsPbBr3 films, and the substrate temperature and post annealing temperature affect the crystallinity of the CsPbBr3 films. Through systematic optimization of the deposition parameters, high-quality CsPbBr3 films with good crystallinity and uniformity are obtained. Planar CsPbBr3 perovskite solar cells with high efficiency of 6.95% in small size (0.09 cm(2)) and 5.37% in large size (1 cm(2)) are fabricated. Moreover, the CsPbBr3 solar cells show good long-term stability under ambient conditions without encapsulation.