Correlation of Dimer-Linker-Induced Conformational Lock with Nonradiative Energy Loss in Organic Solar Cells

作者：Huanhuan Gao, Baobing Fan, Liyang Yu, Yiwen Wang, Ruipeng Li, Wenlin Jiang, Tianqi Chen, Jie Zeng, Francis Lin, Bin Kan, Hongxiang Li, Lei Wang, Alex K.‐Y. Jen · 发表于：ACS Energy Letters · 年份：2024 · DOI：10.1021/acsenergylett.4c02429 · 被引用次数：24 · 研究领域：Organic Electronics and Photovoltaics、Silicon and Solar Cell Technologies、Thin-Film Transistor Technologies

The efficiencies of dimer-based devices still lag those of their small molecule-based counterparts. This is primarily due to the considerable dihedrals in the dimer skeleton, which compromises the molecular packing, thus influencing the charge generation and nonradiative voltage loss (Δ V oc, nr ). Herein, we developed two dimeric acceptors with varied π-linkers to investigate the influence of linker-induced conformational lock on Δ V oc, nr . We find that the helically lapped O -shaped dimer delivers better intermolecular packing than the planar S -shaped one that incorporates a bulkier π-linker. However, its planar skeleton is instead more favorable for forming a compact and ordered stacking with the host acceptor in ternary blend. This possibly promotes exciton dissociation, thus reducing the nonradiative decay of excited states. Moreover, its longer exciton lifetime could offer additional charge-transfer channels. These contributions effectively minimize Δ V oc, nr to 0.195 eV, while delivering a high efficiency approaching 20% in the derived ternary device.