Single‐Junction Organic Photovoltaic Cells with Approaching 18% Efficiency

• Published in: Advanced materials (Weinheim) Vol. 32; no. 19; pp. e1908205 - n/a
• Main Authors: Cui, Yong, Yao, Huifeng, Zhang, Jianqi, Xian, Kaihu, Zhang, Tao, Hong, Ling, Wang, Yuming, Xu, Ye, Ma, Kangqiao, An, Cunbin, He, Chang, Wei, Zhixiang, Gao, Feng, Hou, Jianhui
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01-05-2020
• Subjects: Circuits; Electron transport; Energy conversion efficiency; Materials science; molecular modification; Molecular structure; nonfullerene acceptors; Optimization; organic photovoltaic cells; Photovoltaic cells; power conversion efficiency; Solubility; Transport properties; power conversion efficiency; organic photovoltaic cells; nonfullerene acceptors; molecular modification
• ISSN: 0935-9648; 1521-4095; 1521-4095
• DOI: 10.1002/adma.201908205

Optimizing the molecular structures of organic photovoltaic (OPV) materials is one of the most effective methods to boost power conversion efficiencies (PCEs). For an excellent molecular system with a certain conjugated skeleton, fine tuning the alky chains is of considerable significance to fully explore its photovoltaic potential. In this work, the optimization of alkyl chains is performed on a chlorinated nonfullerene acceptor (NFA) named BTP‐4Cl‐BO (a Y6 derivative) and very impressive photovoltaic parameters in OPV cells are obtained. To get more ordered intermolecular packing, the n‐undecyl is shortened at the edge of BTP‐eC11 to n‐nonyl and n‐heptyl. As a result, the NFAs of BTP‐eC9 and BTP‐eC7 are synthesized. The BTP‐eC7 shows relatively poor solubility and thus limits its application in device fabrication. Fortunately, the BTP‐eC9 possesses good solubility and, at the same time, enhanced electron transport property than BTP‐eC11. Significantly, due to the simultaneously enhanced short‐circuit current density and fill factor, the BTP‐eC9‐based single‐junction OPV cells record a maximum PCE of 17.8% and get a certified value of 17.3%. These results demonstrate that minimizing the alkyl chains to get suitable solubility and enhanced intermolecular packing has a great potential in further improving its photovoltaic performance.
By finely optimizing the alkyl chains, the nonfullerene acceptor named BTP‐eC9 is synthesized and a maximum power conversion efficiency of 17.8% in organic photovoltaic cells is recorded. This work demonstrates that the optimization of alkyl chains to get suitable solubility and enhanced intermolecular packing has a great potential in further improving photovoltaic performance.