Ferrocene‐Induced Perpetual Recovery on All Elemental Defects in Perovskite Solar Cells

Abstract Lead halide perovskites always emerge complex interactions among different elemental ions, which lead to multiple intrinsic imperfections. Elemental defects, such as amine, Pb, and I vacancies at A‐, B‐, and X‐sites, are main issues to deteriorate perovskite solar cells (PSCs). Unfortunately, most previous passivators can only temporarily fix partial inactive vacancies as sacrificial agents. Herein, we propose a recovery agent, ferrocene (Fc), which can form a one‐dimensional perovskite with adequate steric cavities and suitable dissociation energy to recover all elemental defects back to active light‐harvesting perovskites, and regenerate Fc itself meanwhile. Based on this perpetual chain‐reaction cycle, corresponding PSCs maintain >10 000‐hour lifetime in inert condition and >1000‐hour durabilities under various extreme environments, including continuous 85 °C heating, 50 % relative humidity wetting, and 1‐sun light soaking.