High-Performance Perovskite Solar Cells by Doping Didodecyl Dimethyl Ammonium Bromide in the Hole Transport Layer

One of the important components of perovskite solar cells (PSCs) is the hole transport layer (HTL), and the carrier transportation and moisture stability are confronted with two main issues for HTL research. Herein, we introduce didodecyl dimethyl ammonium bromide (DDAB) into the HTL of spiro-OMeTAD. The long alkyl chain of DDAB can increase the hydrophobicity of HTLs and improve environmental stability of the device, and the anion on DDAB can interact with redundant lead, which passivates defects and decreases the trap-state density and nonradiative recombination at the interface. Meanwhile, the introduction of DDAB adjusts the energy array between the HTL and perovskite, and the photovoltage of the device is increased to 1.17 V. Consequently, after doping with DDAB, the PSCs achieve a champion power conversion efficiency of 21.11%, and an unpackaged device could maintain efficiency at 82% after being exposed to 30% relative humidity for 700 h.