Methodologies for >30% Efficient Perovskite Solar Cells via Enhancement of Voltage and Fill Factor

To further improve power conversion efficiency (PCE) toward Shockley−Queisser limit efficiency approaching 32% for a single-junction perovskite solar cell (PSC) based on a lead halide perovskite with a bandgap of about 1.45 eV, it is important to improve the open-circuit voltage and fill factor (FF) significantly without sacrificing short-circuit current density. Herein, the advancements of the formamidinium-rich PSCs with PCEs exceeding 23% from the viewpoints of composition engineering, solvent engineering, additive engineering, and interface engineering are summarized and discussed. Based on the lessons, the possible strategies, methods, and research directions are proposed to further improve voltage and FF for ideal PCEs.