Efficient all-inorganic CsPbI2Br perovskite solar cell with carbon electrode by revealing crystallization kinetics and improving crystal quality

The all-inorganic CsPbI2Br shows potential applications in perovskite solar cell owning to the reasonable band gap and superior thermal stability. However, the power conversion efficiency is rather low comparing to the organic-inorganic hybrid perovskite solar cell, which is mainly induced by the inferior crystal quality. In this paper, we investigate the crystallization kinetics of CsPbI2Br perovskite film and find that the intermediate CsBr is easily formed due to its low solubility, which affects the crystalline quality of CsPbI2Br film. Employment of over-stoichiometric lead reactant (PbI2, PbBr2) or adding other lead-containing compound (PbCl2, Pb(SCN)2) effectively suppress the production of the intermediate CsBr and result in much improved crystallinity of CsPbI2Br, with a grain size of several micrometers. Accordingly, the CsPbI2Br solar cell with carbon electrode shows a stable and high power conversion efficiency of 12.19%, comparing to 9.50% of the control cell.