Additional Organic‐Solvent‐Rinsing Process to Enhance Perovskite Photovoltaic Performance

Methylammonium lead iodide (MAPbI 3 ) perovskite is manipulated through an additional organic‐solvent‐rinsing process during an intermediate film fabrication stage. This additional process includes low‐temperature preannealing following by rinsing the films using isobutyl alcohol (IBA) before final annealing. This partially dissolves the small crystals in the perovskite intermediate and reduces nucleation density. The small crystals recrystallize into larger sizes via a dissolution–crystallization mechanism, leading to a reduction in the grain boundaries and interfacial defects. Preannealing is also crucial in solubility control and for tuning the crystallization. Crystal‐size‐dependent optical band gaps may be attributed to a weak quantum confinement effect. Excess PbI 2 residue is induced at the perovskite surface thanks to the selective solubility of IBA, which improves the passivation of the perovskite surface. A synergistic improvement in grain size and in PbI 2 residue leads to substantial enhancement in device performance. The power conversion efficiency of an optimized photovoltaic device reaches 18.47%, which is more than a 15% increase compared to a control device.