Dynamic hydrogen-bonding enables high-performance and mechanically robust organic solar cells processed with non-halogenated solvent
Haozhe He, Xiaojun Li, Jingyuan Zhang, Zekun Chen, Yufei Gong, Hongmei Zhuo, Xiangxi Wu, Yuechen Li, Shijie Wang, Zhaozhao Bi, Bohao Song, Kangkang Zhou, Tongling Liang, Wei Ma, Guanghao Lu, Long Ye, Lei Meng, Ben Zhang, Yaowen Li, Yongfang Li, Yaowen Li, Yongfang Li, Yongfang Li
Abstract
Developing active-layer systems with both high performance and mechanical robustness is a crucial step towards achieving future commercialization of flexible and stretchable organic solar cells (OSCs). Herein, we design and synthesize a series of acceptors BTA-C6, BTA-E3, BTA-E6, and BTA-E9, featuring the side chains of hexyl, and 3, 6, and 9 carbon-chain with ethyl ester end groups respectively. Benefiting from suitable phase separation and vertical phase distribution, the PM6:BTA-E3-based OSCs processed by o-xylene exhibit lower energy loss and improved charge transport characteristic and achieve a power conversion efficiency of 19.92% (certified 19.57%), which stands as the highest recorded value in binary OSCs processed by green solvents. Moreover, due to the additional hydrogen-bonding provided by ethyl ester side chain, the PM6:BTA-E3-based active-layer systems achieve enhanced stretchability and thermal stability. Our work reveals the significance of dynamic hydrogen-bonding in improving the photovoltaic performance, mechanical robustness, and morphological stability of OSCs.