Ion Transport, Defect Chemistry, and the Device Physics of Hybrid Perovskite Solar Cells

Mastering the complexity of mixed ionic–electronic conduction in hybrid perovskite solar cells is a most critical challenge in the quest for further developing and, eventually, commercializing this technology. In this Perspective, we refer to the literature invoking ion transport in hybrid perovskite devices when interpreting their long time scale behavior. We present an overview on the defect chemistry of methylammonium lead iodide (MAPbI3), and we extend the discussion to some of the questions about composition that are currently being addressed in the field. We further consider the entangled relation between ionic and electronic charge carriers in mixed conducting solar cells at equilibrium as well as out-of-equilibrium conditions. We review and suggest research directions that can bridge defect chemistry with device physics of hybrid perovskite solar cells and enrich the know-how concerning this exciting intersection.