Multifunctional Buried Molecule‐Bridge for High‐Performance Inverted Perovskite Solar Cells
Mingyang Gao, Zeping Ou, Can Wang, Lei Liu, Dingqin Hu, Wei Wan, Peidong Chen, Yi Pan, Shisong Nie, Yuanyi Luo, Pengyan Zhang, Deyong Peng, Ke Zhao, Meirong Fu, Wei Liu, Xia Wang, Wei Zhang, Haoxuan Guo, Yujie Zheng, Zeyun Xiao, Xingyu Gao, Zhu Ma, Rui Wang, Tingming Jiang, Kuan Sun
Abstract
Abstract Carbazole‐based self‐assembled monolayers (SAMs) as an effective hole transportation layer have tremendously advanced the power conversion efficiency (PCE) of inverted perovskite solar cells (PSCs). However, the inhomogeneous distribution of SAMs on substrate and non‐intimate interface contact can bring about significant interfacial energy loss at SAM/perovskite heterojunction. Herein, a small molecule 4‐Bromobenzylphosphnic acid (4Br‐BPA) is constructed as a molecule bridge connecting [4‐(3,6‐dimethyl‐9 H ‐carbazol‐9‐yl) butyl] phosphonic acid (Me‐4PACz) and perovskite, exhibiting multifunctionality on improving the interfacial characteristics. First, the small‐size 4Br‐BPA molecules can partly fill some voids on NiO x /Me‐4PACz anchored with NiO x via phosphonic acid group, meanwhile ameliorating the NiO x surface state. Second, the 4Br‐BPA post‐deposited onto Me‐4PACz interacting with Me‐4PACz via π – π stacking has suppressed charge accumulation at interface, aligned the energy level of NiO x /Me‐4PACz consequently promoting the hole transportation. Third, the interplay between 4Br‐BPA and perovskite enables effective passivation of interfacial traps, and the substrate NiO x /Me‐4PACz/4Br‐BPA with improved wettability has facilitated the perovskite film growth with enhanced crystallization and released residual stress. Consequently, all these benefits have been transformed to an impressive PCE of 26.59% (certified 26.12%). The device based on 4Br‐BPA also demonstrates much improved operational stability, maintaining ≈90% of initial efficiency under 1400 h continuous one‐sun illumination.