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

Simultaneously passivating the perovskite surface defects 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.