Impact of processing atmosphere on nanoscale properties of highly efficient CsMAFAPbI perovskite solar cells.

The fabrication process of triple-cation-halide organic inorganic perovskites must be tightly controlled to make high-efficiency solar cells. After precursor deposition, the amount of oxygen and moisture during the annealing process is important but not always well-monitored and understood. In this study, CsMAFAPbI perovskite films were annealed in different environments, namely N, O and air, to systematically explore the relationship between the evolution of PbI, the grain boundary band bending and the optoelectronic properties.

Coevaporation Stabilizes Tin-Based Perovskites in a Single Sn-Oxidation State.

Chemically processed methylammonium tin-triiodide (CHNHSnI) films include Sn in different oxidation states, leading to poor stability and low power conversion efficiency of the resulting solar cells (PSCs). The development of absorbers with Sn [2+] only has been identified as one of the critical steps to develop all Sn-based devices. Here, we report on coevaporation of CHNHI and SnI to obtain absorbers with Sn being only in the preferred oxidation state [+2] as confirmed by X-ray photoelectron spectroscopy.