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 MAPbI2.91Br0.09 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 MAPbI2.91Br0.09/PTAA:xCe3+/4+ (x = 0.5 wt%) thin film exhibit suppressed charge carrier recombination and shorter charge carrier extraction time. As a result, PSCs by MAPbI2.91Br0.09/PTAA:xCe3+/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.

Perovskite solar cells (PSCs) have aroused vast attention and achieved unprecedented development. However, commercial utilization requires better reliability while maintaining high efficiency. Typically, the uncoordinated band energy configuration and structural defects led to recombination, these bottlenecks have seriously damaged the device performance and limited the further development of PSCs. In addressing those questions, researchers have provided various countermeasures including doping to trim the band structure and solvent engineering to modify the crystallization process and introducing reduced dimensional perovskite to maintain long‐term stability. Herein, a convenient carbazole analog doping strategy is reported by adding a certain amount of bromide‐substituted carbazole analog in the perovskite precursor which succeeded in modifying the surface morphology and optimizing the bandgap structure of the film, additionally maintaining considerable stability. As a result, a champion power conversion energy (PCE) of 22.25% is reached and preserved 85% of the initial PCE while stored in ambient air for more than 1200 h (around 30% relative humidity), and with low hysteresis. A simple but practical doping strategy to fabricate efficient and stable perovskite films in ambient air is provided.