Band edge engineering of lead halide perovskites using carboxylic‐based self‐assembled monolayer for efficient photovoltaics

Perovskite solar cells are promising candidates for low‐cost and efficient photovoltaic markets, but their efficiency is usually limited by the non‐radiative recombination losses at the mismatched interface of perovskite and transport layers. Herein, we show that the band edges of perovskite thin films can be on‐demand engineered by a series of carboxylic‐based self‐assembled monolayers. Experimental and theoretical studies indicate that the functionalized perovskite inherits the polarity of the monolayer with linear dependence of work function on the molecular dipole moments, which enables the management of interfacial charge transport process. Solar cells with 4‐bromophenylacetic acid SAMs achieve about 6.48% enhancement in power conversion efficiency with the champion values over 23%.