High‐Efficiency Perovskite Solar Cells with Imidazolium‐Based Ionic Liquid for Surface Passivation and Charge Transport
Xuejie Zhu, Minyong Du, Jiangshan Feng, Hui Wang, Zhuo Xu, Likun Wang, Shengnan Zuo, Chenyu Wang, Ziyu Wang, Cong Zhang, Xiaodong Ren, Shashank Priya, Dong Yang, Shengzhong Liu
Abstract
Abstract Surface defects have been a key constraint for perovskite photovoltaics. Herein, 1,3‐dimethyl‐3‐imidazolium hexafluorophosphate (DMIMPF 6 ) ionic liquid (IL) is adopted to passivate the surface of a formamidinium‐cesium lead iodide perovskite (Cs 0.08 FA 0.92 PbI 3 ) and also reduce the energy barrier between the perovskite and hole transport layer. Theoretical simulations and experimental results demonstrate that Pb‐cluster and Pb‐I antisite defects can be effectively passivated by [DMIM] + bonding with the Pb 2+ ion on the perovskite surface, leading to significantly suppressed non‐radiative recombination. As a result, the solar cell efficiency was increased to 23.25 % from 21.09 %. Meanwhile, the DMIMPF 6 ‐treated perovskite device demonstrated long‐term stability because the hydrophobic DMIMPF 6 layer blocked moisture permeation.