Enhanced Perovskite Solar Cell Stability and Efficiency via Multi-Functional Quaternary Ammonium Bromide Passivation

The Achilles heel of the perovskite solar cells (PSCs) is the long-term stability under working condition which restricts the commercialization. There are many causes for the poor stability including intrinsic defects in perovskite and humidity-induced degradation. This work systematically investigates the synergistic working mechanism of defect passivation and humidity erosion protection on organic-inorganic metal-halide perovskite with benzyldodecyldimethylammonium bromide (BDDAB). The functionalized parts of halogen anions (Br-) can simultaneously passivate defects and improve the resistance of the humidity erosion by repairing [PbI6](4-) octahedron defects as well as providing hydrophobicity. Moreover, the benzene ring in BDDAB tends to form pi-pi stacking with the benzene ring in the hole transport layer, which increases the intermolecular interaction. Thus, the highest efficiency of 22.08% is obtained by BDDAB-modified PSCs, and 93.29% initial efficiency is retained after aging for 500 h at 80% relative humidity.