14.7% Efficiency Organic Photovoltaic Cells Enabled by Active Materials with a Large Electrostatic Potential Difference

作者：Huifeng Yao, Yong Cui, Deping Qian, Carlito S. Ponseca, Alireza Honarfar, Ye Xu, Jingming Xin, Zhenyu Chen, Ling Hong, Bowei Gao, Runnan Yu, Yunfei Zu, Wei Ma, Pavel Chábera, Tõnu Pullerits, Arkady Yartsev, Feng Gao, Jianhui Hou · 发表于：Journal of the American Chemical Society · 年份：2019 · DOI：10.1021/jacs.8b12937 · 被引用次数：528 · 研究领域：Organic Electronics and Photovoltaics、Conducting polymers and applications、Perovskite Materials and Applications

Although significant improvements have been achieved for organic photovoltaic cells (OPVs), the top-performing devices still show power conversion efficiencies far behind those of commercialized solar cells. One of the main reasons is the large driving force required for separating electron-hole pairs. Here, we demonstrate an efficiency of 14.7% in the single-junction OPV by using a new polymer donor PTO2 and a nonfullerene acceptor IT-4F. The device possesses an efficient charge generation at a low driving force. Ultrafast transient absorption measurements probe the formation of loosely bound charge pairs with extended lifetime that impedes the recombination of charge carriers in the blend. The theoretical studies reveal that the molecular electrostatic potential (ESP) between PTO2 and IT-4F is large, and the induced intermolecular electric field may assist the charge generation. The results suggest OPVs have the potential for further improvement by judicious modulation of ESP.