Enhanced Thermoelectric Performance of a Donor–Acceptor-Based Two-Dimensional Conjugated Polymer with High Crystallinity
Benzhang Li, Xinxin Li, Fan Yang, Yujun Chen, Xianhua Mao, Shuxun Wan, Hong Xin, Sitong Yan, Mingliang Wang, Chunmei Gao, Lei Wang
Abstract
Introducing two-dimensional (2D) conjugated structures to polymers is a feasible way for the design of functionalized polymers due to their good planarity, high electron/hole mobility, thermal stabilities, and so forth. However, the current development of thermoelectric polymers is mainly restricted to the limited modification of the one-dimensional conjugated polymers. Herein, a novel donor–acceptor based 2D conjugated polymer, P(BDTTT-DPP), was designed and synthesized for the enhancement of thermoelectric properties. Compared to the one-dimensional conjugated polymer P(BDT-DPP), P(BDTTT-DPP) showed a higher doping level when doped with the p-type FeCl3 dopant. After doping with 20 mg/mL FeCl3 for 15 min, the optimal power factor of P(BDTTT-DPP) was obtained to be 6.50 μW m–1 K–2 at room temperature, which is 26 times higher than that of P(BDT-DPP). The studies of film morphology and packing structure analysis further indicated that the π–π stacking (010) distance of P(BDTTT-DPP) was maintained after the doping process, and the longer lamellar stacking distance allowed the FeCl3 dopants to efficiently incorporate between the lamellar domains compared to that of P(BDT-DPP), which is favorable to the crystallinity and electron transferability. The results of our work provide valuable insights into the development of donor–acceptor based 2D conjugated polymer for high-performance organic thermoelectric materials.