Abstract

Abstract Lattice defects in perovskite solar cells (PSCs) impede charge carrier recombination, thus limiting power conversion efficiency (PCE) enhancements. Herein, spiro[fluorene-9,9 ‘ - xanthene]-based molecules S1 and S2 were introduced as interfacial materials, improving perovskite crystallization, reducing trap density, and decreasing defects. The integration of S2 as an interlayer increases the average PCE to 21.06% under maximum power point (MPP) tracking, significantly higher than control devices with enhanced photostability.