Influence of Molecular Geometry of Perylene Diimide Dimers and Polymers on Bulk Heterojunction Morphology Toward High‐Performance Nonfullerene Polymer Solar Cells |
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| Authors: | Chen‐Hao Wu Chu‐Chen Chueh Yu‐Yin Xi Hong‐Liang Zhong Guang‐Peng Gao Zhao‐Hui Wang Lilo D Pozzo Ten‐Chin Wen Alex K‐Y Jen |
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| Affiliation: | 1. Department of Materials Science and Engineering, University of Washington, Seattle, USA;2. Department of Chemical Engineering, National Cheng Kung University, Tainan, Taiwan;3. Department of Chemical Engineering, University of Washington, Seattle, USA;4. State Key Laboratory of Organic Solids, Beijing National Laboratory for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing, P. R. China;5. Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan, Taiwan |
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| Abstract: | In this study, we investigate the influence of molecular geometry of the donor polymers and the perylene diimide dimers (di‐PDIs) on the bulk heterojunction (BHJ) morphology in the nonfullerene polymer solar cells (PSCs). The results reveal that the pseudo 2D conjugated poly4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo1,2‐b;4,5‐b′]dithiophene‐2,6‐diyl‐alt‐(4‐(2‐ethylhexyl)‐3‐fluorothieno3,4‐b]thiophene‐)‐2‐carboxylate‐2‐6‐diyl)] (PTB7‐Th) has better miscibility with both bay‐linked di‐PDI (B‐di‐PDI) and hydrazine‐linked di‐PDI (H‐di‐PDI) compared to its 1D analog, poly4,8‐bis(2‐ethylhexyl)oxy]benzo1,2‐b:4,5‐b′]dithiophene‐2,6‐diyl]3‐fluoro‐2‐(2‐ethylhexyl)carbonyl]thieno3,4‐b]thiophenediyl]] (PTB7), to facilitate more efficient exciton dissociation in the BHJ films. However, the face‐on oriented π–π stacking of PTB7‐Th is severely disrupted by the B‐di‐PDI due to its more flexible structure. On the contrary, the face‐on oriented π–π stacking is only slightly disrupted by the H‐di‐PDI, which has a more rigid structure to provide suitable percolation pathways for charge transport. As a result, a very high power conversion efficiency (PCE) of 6.41% is achieved in the PTB7‐Th:H‐di‐PDI derived device. This study shows that it is critical to pair suitable polymer donor and di‐PDI‐based acceptor to obtain proper BHJ morphology for achieving high PCE in the nonfullerene PSCs. |
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| Keywords: | 2D conjugated polymers perylene diimide dimers polymer solar cells nonfullerene acceptors |
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