Perovskite Solar Cells with Interfacial Passivation Employing Undoped Ferrocene-Based Indanone-Type D-π-A Hole-Transporting Materials

In this study, five ferrocene-based D-π-A type hole transport materials (Z01, Z02, S02, L01, and L02) were designed and synthesized. The ferrocene passivation groups were connected to indanone through aldol condensation reactions to regulate perovskite interface defects. Characterizations by ultraviolet–visible (UV–vis), Fourier transform infrared (FTIR), scanning electron microscopy (SEM), and other methods revealed that ferrocene-containing hole transport materials (HTMs) can coordinate with free Pb2+ in perovskite via carbonyl groups, improving the crystallization quality of the film. Among them, the Z02-based device achieved a photoelectric conversion efficiency (PCE) of 16.49%, attributed to the stronger passivation effect of its dicarbonyl structure and hole mobility of 1.01 × 10–5 cm2 V–1 s–1. The HTMs also exhibit excellent thermal stability (decomposition temperature >282 °C), providing a new pathway for interface engineering of efficient perovskite solar cells (PSCs).