Chiral Phosphoserine Reconfigures the Energy Conversion Pathway for Efficient and Stable Sequentially Deposited Perovskite Solar Cells

ABSTRACT FAPbI 3 perovskite solar cells (PSCs) fabricated via sequential deposition hold great promise for high photovoltaic performance. However, two bottlenecks remain persistent: transport‐limited conversion that leaves residual PbI 2 and the high thermal prerequisite to drive the δ‐to‐α phase transition, both of which deteriorate optoelectronic properties and accelerate degradation under illumination. Here, we introduced chiral molecules serine and phosphoserine (OPS) into the PbI 2 precursor to raise the reactivity of the inorganic scaffold toward the organic salt, and lowered the kinetic barrier for α‐FAPbI 3 . Regulation of crystallization kinetics and phase evolution in perovskite films was thereby achieved. The optimized films exhibited enlarged grain sizes and enhanced quasi‐Fermi level splitting. In parallel, density functional theory calculations combined with statistical data analysis clarified the distinctions among chiral variants. As a result, regular PSCs incorporating O‐phospho‐D‐serine (D‐OPS) achieved a champion power conversion efficiency of 26.04% under AM 1.5G illumination and retained 90.2% of their initial efficiency after 1000 h of maximum power point tracking. This strategy of reconstructing energy conversion pathways was also successfully extended to inverted PSCs, demonstrating its broad applicability for stable, high‐performance perovskite photovoltaics.