Minimizing Voltage Losses via Synergistically Reducing Hetero‐Interface Energy Offset for High Efficiency Perovskite Solar Cells

Abstract The open circuit voltage ( V OC ) losses at multiple interfaces within perovskite solar cells (PSCs) limit the improvements in power conversion efficiency (PCE). Herein, a tailored strategy is proposed to reduce the energy offset at both hetero‐interfaces within PSCs to decrease the V OC losses. For the interface of perovskite and electron transport layer where exists a mass of defects, it uses the pyromellitic acid to serve as a molecular bridge, which reduces non‐radiative recombination and energy level offset. For the interface of perovskite and hole transport layer, which includes a passivator of PEAI, the detrimental effect (negative shift of work function) of PEAI passivation and optimizing the interface energy level alignment are neutralized by incorporating (2‐(4‐(bis(4‐methoxyphenyl)amino)phenyl)‐1‐cyanovinyl)phosphonic acid. Owing to synergistically reduced hetero‐interface energy offset, the PSCs achieve a PCE of 25.13%, and the V OC is increased from 1.134 to 1.174 V. In addition, the resulting PSCs possess enhanced stability, the unencapsulated PSCs can maintain ≈96% and ≈97% of their initial PCE after 2000 h of aging under ambient conditions and 210 h under operation conditions.