Deposition of High Number H-Phases by Vapor Deposition Routes

FAPbI3 perovskites are known to degrade in the 2H crystal phase by switching from corner sharing PbI3 octahedra to face sharing. Hybrid structures (H-phases) between pure edge sharing and face sharing octahedra are possible, and their presence has been observed experimentally as impurities in perovskite films. Crystal engineering of mixtures of corner and face sharing octahedra enabled new functionality in oxide perovskites.[1] Analogously, it is expected that the synthesis of phase pure H-phases with different degrees of face or edge sharing will enable similar results. Furthermore, the study of H-phases will benefit the interpretation of the photovoltaic properties of 3D perovskite films, as these phases are formed as impurities in most FA- and Cs-based films.[2]<br/>In this contribution we demonstrate the deposition of thin films with complex arrangements of corner and face sharing PbI3 octahedra (high number H-phases). We correlate crystal structure and optical properties of these compounds and discuss the potential benefits of the application of these materials as well as their impact on the photovoltaic performances of 3D FA- and Cs- based solar cells.<br/>[1] J.S. Park, …A. Walsh, ACS Energy Lett. 2020, 5, 7, 2231–2233<br/>[2] K.A. Elmestekawy, L. Hertz, ACS Nano 2022, 16, 6, 9640–9650