High-Efficiency Organic Solar Cells Based on Asymmetric Acceptors Bearing One 3D Shape-Persistent Terminal Group |
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| Authors: | Hao Lu Hui Jin Hao Huang Wenxu Liu Zheng Tang Jianqi Zhang Zhishan Bo |
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| Affiliation: | 1. Key Laboratory of Energy Conversion and Storage Materials, College of Chemistry, Beijing Normal University, Beijing, 100875 P. R. China;2. Center for Advanced Low-dimension Materials, State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, College of Materials Science and Engineering, Donghua University, Shanghai, 201620 P. R. China;3. CAS Key Laboratory of Nanosystem and Hierarchical Fabrication, National Center for Nanoscience and Technology, Beijing, 100190 P. R. China |
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| Abstract: | Three asymmetric non-fullerene acceptors (LL2, LL3, and LL4) are designed and synthesized with one norbornyl-modified 1,1-dicyanomethylene-3-indanone (CBIC) terminal group and one chlorinated 1,1-dicyanomethylene-3-indanone (IC-2Cl) terminal group. The three-dimensional shape-persistent CBIC terminal group can effectively enhance the solubility and tune the packing mode of acceptors. Compared with their symmetric counterparts (LL2-2Cl, LL3-2Cl, and LL4-2Cl) bearing two IC-2Cl terminals, the asymmetric acceptors show improved solubilities, giving rise to enhanced crystallinity and favored nanomorphology for charge transport in the blend films with PBDB-T. Asymmetric acceptors based organic solar cells (OSCs) also show much lower voltage loss due to their higher ECT and EQEEL values. Therefore, they exhibit 17?27% higher power conversion efficiency (PCE) than OSCs based on the corresponding symmetric acceptors. Among these six acceptors, LL3 with a central benzotriazole core shows the best PCE of 16.82% with an outstanding Jsc of 26.97 mA cm?2 and a low nonradiative voltage loss (ΔVnr) of 0.18 V, the best values for PBDB-T based OSCs. The Jsc and ΔVnr also represent the best reported for asymmetric non-fullerene acceptors-based OSCs to date. The results demonstrate that the combination of the unique CBIC terminal group with the asymmetric strategy is a promising way to enhance the performance of OSCs. |
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| Keywords: | asymmetric non-fullerene acceptors organic solar cells solubility terminal engineering voltage loss |
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