Unraveling the influence of non-fullerene acceptor molecular packing on photovoltaic performance of organic solar cells

• Published in: Nature communications Vol. 11; no. 1; p. 6005
• Main Authors: Ye, Linglong, Weng, Kangkang, Xu, Jinqiu, Du, Xiaoyan, Chandrabose, Sreelakshmi, Chen, Kai, Zhou, Jiadong, Han, Guangchao, Tan, Songting, Xie, Zengqi, Yi, Yuanping, Li, Ning, Liu, Feng, Hodgkiss, Justin M., Brabec, Christoph J., Sun, Yanming
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 26.11.2020; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/299/946; 639/4077/4072/4062; Assembly; Backbone; BASIC BIOLOGICAL SCIENCES; Carrier transport; Chains; Charge transport; Energy conversion efficiency; Fullerenes; Humanities and Social Sciences; multidisciplinary; Packing; Photovoltaic cells; Photovoltaics; Radiative recombination; Recombination; Rings (mathematics); Science; Science (multidisciplinary); Solar cells; Solar power; Solid state; Stacking
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-020-19853-z

In non-fullerene organic solar cells, the long-range structure ordering induced by end-group π–π stacking of fused-ring non-fullerene acceptors is considered as the critical factor in realizing efficient charge transport and high power conversion efficiency. Here, we demonstrate that side-chain engineering of non-fullerene acceptors could drive the fused-ring backbone assembly from a π–π stacking mode to an intermixed packing mode, and to a non-stacking mode to refine its solid-state properties. Different from the above-mentioned understanding, we find that close atom contacts in a non-stacking mode can form efficient charge transport pathway through close side atom interactions. The intermixed solid-state packing motif in active layers could enable organic solar cells with superior efficiency and reduced non-radiative recombination loss compared with devices based on molecules with the classic end-group π–π stacking mode. Our observations open a new avenue in material design that endows better photovoltaic performance. Non-fullerene acceptors are crucial for realising efficient charge transport and high power conversion in organic solar cells, yet the relationship of molecular packing and carrier transport is not well-understood. Here, the authors study the effect of side-chain engineering on the backbone assembly and the corresponding charge transport pathway.