Why Lead Methylammonium Tri-Iodide Perovskite-Based Solar Cells Require a Mesoporous Electron Transporting Scaffold (but Not Necessarily a Hole Conductor)

Abstract

CH₃NH₃PbI₃-based solar cells were characterized with electron beam-induced current (EBIC) and compared to CH₃NH₃PbI_3–xCl_x ones. A spatial map of charge separation efficiency in working cells shows p-i-n structures for both thin film cells. Effective diffusion lengths, L_D, (from EBIC profile) show that holes are extracted significantly more efficiently than electrons in CH₃NH₃PbI₃, explaining why CH₃NH₃PbI₃-based cells require mesoporous electron conductors, while CH₃NH₃PbI_3–xCl_x ones, where L_D values are comparable for both charge types, do not.