<i>N</i>‐Heterocyclic Olefin Type Ionic Liquid with Innate Soft Lewis‐Base Character as an Effective Additive for Hybrid Quasi‐2D and 3D Perovskite Solar Cells
Zhonggao Zhou, Lihua Li, Bolun Li, Jing Li, Tianyong Liu, Xi Huang, Shaobin Tang, Hongdeng Qiu, Wanzhu Cai, Shi‐Yong Zhang, Kan Li, Guohai Xu, Hongyu Zhen
Abstract
Abstract In optimizing perovskites with ionic liquid (IL), the comparative study on Lewis acid‐base (LAB) and hydrogen‐bonding (HB) interactions between IL and perovskite is lacking. Herein, methyl is substituted for hydrogen on 2‐position of imidazolium ring of N ‐heterocyclic carbene (NHC) type IL IdH to weaken HB interactions, and the resulting N ‐heterocyclic olefin (NHO) type IL IdMe with softer Lewis base character is studied in both hybrid quasi‐2D (Q‐2D) and 3D perovskites. It is revealed that IdMe participates in constructing high‐quality Q‐2D perovskite (n = 4) and provides stronger passivation for 3D perovskite compared with IdH. Power conversion efficiency (PCE) of Q‐2D PEA 2 MA 3 Pb 4 I 13 perovskite solar cells (PVSCs) is boosted to 17.68% from 14.03%. PCE and device stability of 3D PVSCs enhances simultaneously. Both theoretical simulations and experimental results show that LAB interactions between NHO and Pb 2+ take the primary optimization effects on perovskite. The success of engineering LAB interactions also offers inspiration to develop novel ILs for high‐performance PVSCs.