Prof. Qingdong Zheng, Nanjing University, China
Report Title： Nonfullerene acceptors based on ladder-type heteroheptacenes without sp3-hybridized carbons
Abstract: Control over the intermolecular interaction as well as the molecular orientation of organic semiconductors with respect to the substrate plays a critical role in determining the performance of polymer solar cells (PSCs). In this talk, we will focus on the development of novel electron-transporting materials based on ladder-type heteroheptacenes without sp3-hybridized carbons for efficient PSCs. A series of ladder-type heteroheptacene-based small molecules with branched or unbranched side chains flanked in different positions of their conjugated backbone, or with varied electron-withdrawing end groups flanked on the same conjugated backbone, were designed and synthesized to investigate the effect of side-chains and end group on the crystallinity, molecular orientation, and optoelectronic properties of these ladder-type heteroheptacene-based semiconductors. Furthermore, we report the effect of noncovalent intramolecular interactions on the photovoltaic performance of the non-fullerene acceptors. The removal of the sp3-hybridized carbons leads to novel non-fullerene acceptors with efficient electron transport. As result, the best-performance non-fullerene acceptor with optimized molecular orientation affords an outstanding power conversion efficiency of 17.81% which is the highest among all the A-D-A type non-fullerene acceptors reported to date.
Brief: Qingdong Zheng is a Professor in the College of Engineering and Applied Sciences at Nanjing University. He received his Ph.D. degree in chemistry from the State University of New York at Buffalo, the USA in 2005. After carrying out his postdoctoral research at Johns Hopkins University, he joined and worked as a full professor in the Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences (Jan. 2010 to Nov. 2021). His main interests focus on multifunctional molecular materials and devices and in particular on the fields of semiconducting materials and related interfacial materials for organic solar cells. He has published over 140 papers in peer-reviewed international journals.