TiO Electron Transport Layer with p-n Homojunctions for Efficient and Stable Perovskite Solar Cells.

Low-temperature processed electron transport layer (ETL) of TiO that is widely used in planar perovskite solar cells (PSCs) has inherent low carrier mobility, resulting in insufficient photogenerated electron transport and thus recombination loss at buried interface. Herein, we demonstrate an effective strategy of laser embedding of p-n homojunctions in the TiO ETL to accelerate electron transport in PSCs, through localized build-in electric fields that enables boosted electron mobility by two orders of magnitude. Such embedding is found significantly helpful for not only the enhanced crystallization quality of TiO ETL, but the fabrication of perovskite films with larger-grain and the less-trap-states.