Mesoporous BaTiO₃/TiO₂ Double Layer for Electron\nTransport in Perovskite Solar Cells

Abstract

We\nreport on the effect of BaTiO₃/TiO₂ mesoporous\ndouble layer (MDL) in the electron transport layer (ETL) of perovskite\nsolar cells and enhancement of the photovoltaic performance. The conversion\nefficiency was enhanced from 9.89% for TiO₂ mesoporous\nsingle layer (MSL) to 12.4% for BaTiO₃/TiO₂ MDL.\nThe CH₃NH₃PbI₃ crystal size on the\nBaTiO₃/TiO₂ MDL was larger. The larger CH₃NH₃PbI₃ crystals resulted in the better\nlight absorption and improved <i>J</i>_SC. Moreover, <i>V</i>_OC was also improved by suppressing a charge\nrecombination, which is attributable to the fewer CH₃NH₃PbI₃ crystal boundaries and band structure of BaTiO₃/TiO₂ MDL. The results suggest that using BaTiO₃ as the second layer of the TiO₂ mesoporous layer\nis a promising way to boost the performance of perovskite solar cells.