Facile surface modification of CH3NH3PbI3 films leading to simultaneously improved efficiency and stability of inverted perovskite solar cells

The intrinsic stability issues of organo-metal halide perovskite materials induced by moisture, heat, light and the presence of an electric field constitute big obstacles that are preventing perovskite solar cells (PSCs) from industrial application. Herein, we have demonstrated that when a hydrophobic organic acid molecule, 4-dimethylaminobenzoic acid, is introduced to modify the top surface of a CH3NH3PbI3 thin film, it is a facile way to simultaneously enhance the stability and efficiency of the corresponding PSCs. This surface modification can not only improve the perovskite film’s electronic quality but also provide it with a certain waterproofing capability. Accordingly, the efficiency of the inverted PSC is improved from 17.43% to 19.87%. More encouragingly, after 1 sun light soaking, 85 °C thermal aging, and high humidity (70%) aging for 1000 hours, the modified CH3NH3PbI3 based PSCs can retain 91%, 81% and 98% efficiency, respectively.