Surpassing 90% Shockley-Queisser limit in 1.79 eV wide-bandgap perovskite solar cells using bromine-substituted self-assembled monolayers

• Published in: Energy & environmental science Vol. 18; no. 4; pp. 1847 - 1855
• Main Authors: Wei, Zhouyin, Zhou, Qilin, Niu, Xiuxiu, Liu, Shunchang, Dong, Zijing, Liang, Haoming, Chen, Jinxi, Shi, Zhuojie, Wang, Xi, Jia, Zhenrong, Guo, Xiao, Guo, Renjun, Meng, Xin, Wang, Yu-Duan, Li, Nengxu, Xu, Zhiguang, Li, Zaifang, Aberle, Armin Gerhard, Yin, Xinxing, Hou, Yi
• Format: Journal Article
• Published: 18.02.2025
• ISSN: 1754-5692; 1754-5706
• DOI: 10.1039/d4ee04029e

All-perovskite tandem solar cells (TSCs) hold the promise of surpassing the efficiency limits of single-junction solar cells. However, enhancing TSC efficiency faces the challenge of significant open-circuit voltage ( V OC ) loss in the wide-bandgap (WBG) subcell. In this study, we employed a bromine-substitution strategy to develop a novel self-assembled monolayer, (4-(3,11-dibromo-7 H -dibenzo[ c , g ]carbazol-7-yl)butyl)phosphonic acid ( DCB-Br-2 ), as the hole-transporting layer for 1.79-eV WBG perovskite solar cells. The bromine in DCB-Br-2 donates a pair of non-bonded electrons to uncoordinated Pb 2+ ions or halide vacancies, enhancing interaction with the perovskite layer and suppressing interfacial non-radiative recombination. DCB-Br-2 also adjusts energy level alignment, facilitating fast hole extraction. The optimized WBG solar cell achieved a maximum V OC of 1.37 V, surpassing 90% of the Shockley-Queisser limit. Combined with a 1.25-eV narrow-bandgap subcell, this enabled a two-terminal all-perovskite TSC with a champion power conversion efficiency of 27.70%, advancing the development of high-performance tandem devices. DCB-Br-2 is used as a hole-transporting layer for 1.79 eV wide-bandgap perovskite solar cells. Its stronger interaction with the perovskite and better energy level alignment enable the achievement of a notable V OC of 1.37 V.