Efficient Carbon‐Based Perovskite Solar Cells Passivated by Alkylammonium Chloride

Hole‐transport layer (HTL)‐free carbon‐based perovskite solar cells (C‐PSCs) have garnered significant attention in the research community due to their cost‐effectiveness and high stability. However, the absence of a traditional HTL can lead to substantial nonradiative recombination of charge carriers between the perovskite layer and the carbon electrode, significantly impacting efficiency. Herein, the performance effects of different alkylammonium chlorides, including butylammonium chloride, octylammonium chloride, and dodecylammonium chloride (DACl), on perovskite (FA 0.1 MA 0.9 PbI 3 ) are investigated to produce high‐performance HTL‐free C‐PSCs. Following passivation, the film exhibits a more uniform grain size distribution and fewer grain boundary defects. Furthermore, with an increase in the alkyl chain length, enhanced interactions with the perovskite film result in reduced trap state density and increased carrier lifetime. After DACl passivation, the C‐PSC achieves a remarkable power conversion efficiency of 16.56% and a high open‐circuit voltage ( V oc ) of 1.074 V. The V oc enhancement is primarily attributed to the better energy‐level alignment, effectively improving hole transport and electron‐blocking capabilities while suppressing nonradiative recombination. Additionally, they demonstrate exceptional hydrophobic characteristics and robust stability in the presence of humidity, making them particularly promising for future practical applications in the field of photovoltaics.