Adding a Third Component with Reduced Miscibility and Higher LUMO Level Enables Efficient Ternary Organic Solar Cells
Ruijie Ma, Tao Liu, Zhenghui Luo, Ke Gao, Kai Chen, Guangye Zhang, Wei Gao, Yiqun Xiao, Tsz‐Ki Lau, Qunping Fan, Yuzhong Chen, Lik‐Kuen Ma, Huiliang Sun, Guilong Cai, Tao Yang, Xinhui Lu, Ergang Wang, Chuluo Yang, Alex K.‐Y. Jen, He Yan
Abstract
It is widely known that the miscibility between donor and acceptor is a crucial factor that affects the morphology and thus device performance of nonfullerene organic solar cells (OSCs). In this Letter, we show that incorporating a third component with lower miscibility and higher lowest unoccupied molecular orbital (LUMO) level into the state-of-the-art PM6:Y6 system can significantly enhance the performance of devices. The best results of the ternary devices are achieved by adding a small molecular acceptor named ITCPTC (∼5% w/w), which significantly improves the power conversion efficiency (PCE) of the host system from 16.44% to 17.42%. The higher LUMO of the third component increases the open-circuit voltage (VOC), while the low miscibility enlarges the domains and leads to improved short-circuit current density (JSC) and fill factor (FF). The efficacy of this strategy is supported by using other nonfullerene third components including an asymmetric small molecule (N7IT) and a polymer acceptor (PF2-DTC), which play the same role as ITCPTC and boost the PCEs to 16.96% and 17.04%, respectively. Our approach can be potentially applied to a wide range of OSC material systems and should facilitate the development of the OSC field.