Triphenylamine-Based Hole-Transporting Ligands for 2D/3D FAPbI<sub>3</sub> Perovskite Solar Cells
Huaiman Cao, Tianshu Li, Liangyu Zhao, Qiang Yue, Xufan Zheng, Shouye Dai, Yulong Chen, Yong Zhu, Liang Zhao, Rui Cai, Zhiguang Sun, Fei Li, Yingguo Yang, Lijun Zhang, Hin‐Lap Yip, Ze Yu
Abstract
Two-dimensional (2D) perovskites suffer from poor charge transport due to the insulating nature of typically used organic spacers. Here, we develop a triphenylamine (TPA)-functionalized semiconducting ligand, namely, DPA-PEAI, in which the TPA moiety is tethered to the ethylammonium cation. Crystallographic analysis of n = 1 2D perovskite (DPA-PEA) 2 PbI 4 reveals that the propeller-like geometry and enriched phenyl rings of the TPA tail enable the formation of multifarious π-stacking interconnections between neighboring ligands. Theoretical calculations further unveil that both the binding energy and hole transfer integral are augmented between the adjacent DPA-PEA cations, in contrast to the widely used phenylethylammonium (PEA) counterpart. This cross-electronic coupling feature allows the formation of multiple hole-transfer pathways within DPA-PEA-based 2D perovskites, enabling efficient out-of-plane charge transport, as confirmed by a set of characterizations. As a consequence, 2D/3D FAPbI 3 -based PSCs employing DPA-PEAI afford a champion efficiency of 25.7%, which ranks among the best efficiencies reported for conjugative ligands.