Sustainable Molecular Passivation via Heat-Induced Disaggregation and Redox Reactions for Inverted Perovskite Solar Cells
Ziyi Li, Anxin Sun, Congcong Tian, Rongshan Zhuang, Yiting Zheng, Xiling Wu, Beilin Ouyang, Jiajun Du, Jingyu Cai, Jinling Chen, Teng Xue, Ran Li, Tiantian Cen, Yuyang Zhao, Kaibo Zhao, Qianwen Chen, Chun‐Chao Chen
Abstract
Molecular materials with high structure-design freedom are used as new interface passivators to reduce nonradiative recombination in inverted perovskite solar cells (PSCs). However, most molecular modifiers are unable to achieve a long-term passivation effect due to self-aggregation. Here, the molecular modifier 1-methyl-2-thiomethyl-1 H -imidazole-5-carboxylate (SMC) with ester and thiol groups is carefully developed. The ester groups weaken self-aggregation triggered by intermolecular hydrogen bonds, making such aggregations easier to disassemble during heating to form a net-like insulating layer with random openings, which dramatically increase charge transport. More importantly, the electron transfer between thiol and disulfide can accelerate the elimination of Pb 0 and I 2 by redox reactions to prevent phase separation. Ultimately, the optimized inverted PSCs with bandgaps of 1.68 and 1.55 eV showed surprising fill factors of 84.83% and 86.18%, resulting in champion efficiencies of 23.45% (certified 22.98%, which is the highest to date for wide-bandgap) and 25.71% (certified 25.28%), respectively. Remarkably, both unencapsulated devices maintained over 94% of their initial efficiency under maximum power point tracking for 600 h (50 °C) and 1000 h (65 °C), respectively, confirming impressive long-term operational stability.