Dual Metal‐Assisted Defect Engineering towards High‐Performance Perovskite Solar Cells

Perovskite solar cells (PSCs) have witnessed an unprecedentedly rapid development, especially in terms of power conversion efficiency (PCE). However, the solution-processed perovskite films inevitably possess numerous crystallographic defects (e.g., halide vacancies), which has been shown to incur non-radiative charge recombination and ion migration, thus limiting the enhancement of the PCE and stability of PSCs. Here, a novel dual metal (i.e., divalent and monovalent metal ions) modification strategy is reported for simultaneously reducing the defects, immobilizing the halide anions, and preventing ion loss from perovskite during post-annealing process. Accordingly, this strategy significantly reduces non-radiative recombination, enhancing the PCE by approximate to 12% and mitigating the current density-voltage (J-V) hysteresis effect in resultant devices compared to undoped counterparts. As a result, a champion PCE exceeding 22% and a high open-circuit voltage (V-oc) of 1.16 V is obtained for dual metal ions-modified PSCs. The optimized devices also exhibit extended lifespan upon the dual metal treatment. The study provides a new defect engineering strategy toward more efficient and stable perovskite photovoltaics.