Becker, P.; Márquez, J.A.; Just, J.; Al-Ashouri, A.; Hages, C.; Hempel, H.; Jost, M.; Albrecht, S.; Frahm, R.; Unold, T.: Low Temperature Synthesis of Stable γ-sPbI3 Perovskite Layers for Solar Cells Obtained by High Throughput Experimentation. Advanced Energy Materials 9 (2019), p. 1900555/1-8
Open Accesn Version

The structural phases and optoelectronic properties of co-evaporated CsPbI3 thin films with a wide range of [CsI]/[PbI2] compositional ratios are investigated. We find that for CsI-rich growth conditions, CsPbI3 can be synthesized directly at low temperature into the distorted perovskite g-CsPbI3 phase with Schottky-type defects and without detectable secondary phases. In contrast, PbI2-rich growth conditions are found to lead to the non-perovskite d-phase. Photoluminescence spectroscopy and optical pump-THz probe measurements show carrier lifetimes larger than 75 ns and charge carrier (sum) mobilities larger 60 cm2/Vs for the g-phase, indicating their suitability for high efficiency solar cells. Building on these results p-i-n type solar cells with a maximum efficiency exceeding 12 % and high shelf stability of more than 1200 h are demonstrated.