Prof. Liu Yunqi’ group from the Institute of Chemistry of Chinese Academy of Sciences developed a general two-step approach to obtain electron-withdrawing group (EWG) substituted acceptors based on the BAI unit. The result was published at Advanced Materials (Adv. Funct. Mater. 29, 1804839, 2019). This approach was effective to introduce various EWGs (such as F, Cl, Br, CN or CF3) into BAI at different substituted positions. Four polymers of PBAI-V, P2FBAI-V, P2ClBAI-V, and P4OBAI-V were developed by this method. All the polymers showed ambipolar transport behaviors. Particularly, P2ClBAI-V showed remarkable hole and electron mobilities of 4.04 and 1.46 cm_² V^-1 s^-1. Moreover, the general two-step approach can achieve various EWG substituted BAI acceptors, which will significantly enrich the library of ambipolar polymers. 2D grazing incident X-ray diffractions (2D-GIXRD) carried out at 1W1A station of Beijing Synchrotron Radiation Facility were used to explore the crystalline nature of the polymers. The results show that the introduction of chlorine atoms in the BAI molecule does not cause obvious steric hindrance, which is effective intermolecular charge transport for carriers

Fig. Synthetic route to substituted BAI

Article:

Jie Yang, Yaqian Jiang, Zeyi Tu, Zhiyuan Zhao, Jinyang Chen, Zhengran Yi, Yifan Li, Shuai Wang,^* Yuanping Yi,^* Yunlong Guo,^* and Yunqi Liu^*. High-Performance Ambipolar Polymers Based on Electron-Withdrawing Group Substituted Bay-Annulated Indigo . Adv. Funct. Mater. 2019, 29, 1804839.