Thermal-Induced Cerium-Doped Perovskite Solar Cells with a Fill Factor Exceeding 81%

Hybrid organic-inorganic perovskites have attracted significant attention due to their remarkable optoelectronic properties and the feasibility of cost-effective, high-throughput manufacturing of perovskite solar cells (PSCs). The present p-i-n PSCs have poor film-forming ability on poly[bis(4-phenyl)(2,4,6-trimethylphenyl)-amine] (PTAA) film, resulting in a great number of defects within perovskite. Herein, the cerium ion (Ce3+) into the PTAA layer is successfully incorporated, which is thermal-induced transferred onto the perovskite lattice and surface layer, by replacing Pb2+ in partial or uncoordinated metalsites and Ce3+-Ce4+ ion pair to suppress the bulk/surface defects, leading to a significantly enhanced power conversion efficiency (PCE). Systemically studies demonstrate that thermal-induced Ce3+/4+-doped MAPbI(2.91)Br(0.09) thin film possesses superior film morphology with a uniform surface, suppressed nonradiative recombination, and enhanced crystallinity due to fewer bulk/surface defects. Moreover, PSCs by MAPbI(2.91)Br(0.09)/PTAA:xCe(3+/4+) (x = 0.5 wt%) thin film exhibit suppressed charge carrier recombination and shorter charge carrier extraction time. As a result, PSCs by MAPbI(2.91)Br(0.09)/PTAA:xCe(3+/4+) (x = 0.5 wt%) thin film exhibit PCE of 21.32% with significantly increased fill factor (FF) of 81.17% and long-term stability. All these results indicate that the approach provides a facile way to incorporate rare-earth ions into perovskites to boost the performance of PSCs.