Unraveling the Impact of Hole Transport Materials on Photostability of Perovskite Films and p-i-n Solar Cells.

We investigated the impact of a series of hole transport layer (HTL) materials such as Poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), NiO, poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine (PTAA), and polytriarylamine (PTA) on photostability of thin films and solar cells based on MAPbI, CsFAPbI, CsMAFAPbI, CsMAFAPb(BrI), and CsFAPb(BrI) complex lead halides. Mixed halide perovskites showed reduced photostability in comparison with similar iodide-only compositions. In particular, we observed light-induced recrystallization of all perovskite films except MAPbI with the strongest effects revealed for Br-containing systems.