Perovskite with inhomogeneous composition: presence of the Cl-rich layer improves the device performance

Abstract A perovskite compositional difference was engineered at the perovskite/electron transport layer (ETL) interface. The devices with inhomogeneous perovskite composition achieve the best power conversion efficiency of 16.1% under the optimal conditions, compared with 12.5% for the control, and the device stability is also improved. Further characterizations indicate that the performance enhancement is due to the larger perovskite grain size with less pinholes, the improved charge extraction at the perovskite/ETL interface, and the reduced charge recombination. This modification effect is induced by constructing an additional Cl-rich layer on bottom of the primary CH3NH3PbI3 film.