Reconfiguration toward Self-Assembled Monolayer Passivation for High-Performance Perovskite Solar Cells

Self-assembled monolayers (SAMs) with unique ordered structures and varied anchoring groups have emerged as an excellent interfacial strategy for perovskite solar cells (PSCs). Herein, 3-carboxypropyl-triphenyl phosphonium bromide with the participation of the fullerene derivative [6,6]-phenyl-C-61-butyric acid (PCBA) as functionalized C-PCBA SAM, is introduced to stably modify the TiO2/perovskite interface. In the meantime, with strong fullerene cage-iodide interaction, ordered C-PCBA SAM can passivate interfacial defects and improve the electron transportation. A high efficiency of 24.8% and stabilized power output of 23.9%, are achieved with negligible hysteresis, which is among the best performances for TiO2 planar PSCs. This modified cell also exhibits significantly improved stabilities under different testing conditions; non-encapsulated devices can maintain 95% of initial efficiency after 1000 h thermal stability testing at 85 degrees C and 85% after 700 h continuous illumination (approximate to 100 mW cm(-2)) and maximum-power-point tracking. This work provides valuable inspiration for developing highly efficient and stable PSCs by using a convenient SAM reconfiguration strategy.