Highly Efficient and Stable Perovskite Solar Cells by Introducing a Multifunctional Surface Modulator

Simultaneously passivating the perovskite surface defects (VI, Pbi) and suppressing Li+ ions diffusion of hole transport layer (HTL) are still challenging issues. Herein, we report an effective “ three birds with one stone ” strategy by utilizing sodium 4,4'‐(1,4‐phenylenebis(oxy))bis(butane‐1‐sulfonate) (ZR3) containing sulfonic acid groups (SO3−) and Na+ ions as a multifunctional surface treatment modulator to simultaneously address the above issues. It is found that ZR3 is not only capable of passivating the Pb‐related defects at the surface of perovskite by the SO3‐ group, but also possesses the remarkable ability to passivate the halide defects with Na+ ions. Meanwhile, ZR3 treatment enables the enhanced exciton dissociation of perovskite, better energy level alignment with hole transport layer (HTL), improved hole extraction/transfer from perovskite layer into HTL, and reduced charge carrier recombination in device. Therefore, it results in the enhanced power conversion efficiency (PCE) of 25.34% in ZR3‐based n‐i‐p device from 22.97% for the control device. Specifically, p‐i‐n PSCs with ZR3 also achieves an improved PCE of 25.96% with respect to the pristine one (23.99%), proving the universality of ZR3 for PSCs. Moreover, the stabilities of ZR3‐treated devices are significantly enhanced owing to Li+ ions migration suppressing and perovskite defects reduction.