Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of Education, Key Laboratory of Polymer Chemistry and Physics of Ministry of Education, Center of Soft Matter Science and Engineering, College of Chemistry and Molecular Engineering, Peking University, Beijing, 100871, China.
Beijing National Laboratory for Molecular Sciences (BNLMS), CAS Key Laboratory of Organic Solids, Institute of Chemistry, Chinese Academy of Sciences, Beijing, 100190, China.
Adv Mater. 2018 Oct;30(43):e1802850. doi: 10.1002/adma.201802850. Epub 2018 Sep 4.
Conjugated polymers with high thermoelectric performance enable the fabrication of low-cost, large-area, low-toxicity, and highly flexible thermoelectric devices. However, compared to their p-type counterparts, n-type polymer thermoelectric materials show much lower performance, which is largely due to inefficient doping and a much lower conductivity. Herein, it is reported that the development of a donor-acceptor (D-A) polymer with enhanced n-doping efficiency through donor engineering of the polymer backbone. Both a high n-type electrical conductivity of 1.30 S cm and an excellent power factor (PF) of 4.65 µW mK are obtained, which are the highest reported values among D-A polymers. The results of multiple characterization techniques indicate that electron-withdrawing modification of the donor units enhances the electron affinity of the polymer and changes the polymer packing orientation, leading to substantially improved miscibility and n-doping efficiency. Unlike previous studies in which improving the polymer-dopant miscibility typically resulted in lower mobilities, the strategy maintains the mobility of the polymer. All these factors lead to prominent enhancement of three orders magnitude in both the electrical conductivity and the PF compared to those of the non-engineered polymer. The results demonstrate that proper donor engineering can enhance the n-doping efficiency, electrical conductivity, and thermoelectric performance of D-A copolymers.
具有高热电性能的共轭聚合物使低成本、大面积、低毒性和高柔韧性的热电器件的制造成为可能。然而，与 p 型聚合物相比，n 型聚合物热电材料的性能要低得多，这主要是由于掺杂效率不高和电导率低。在此，据报道，通过聚合物主链的供体工程，开发了一种供体-受体（D-A）聚合物，以提高 n 型掺杂效率。得到了 1.30 S cm 的高 n 型电导率和 4.65 µW mK 的优异功率因子（PF），这是 D-A 聚合物中报道的最高值。多种表征技术的结果表明，供体单元的电子受主修饰增强了聚合物的电子亲和力并改变了聚合物的堆积取向，从而显著提高了聚合物的混溶性和 n 型掺杂效率。与以前的研究不同，改善聚合物-掺杂剂的混溶性通常会导致迁移率降低，而该策略保持了聚合物的迁移率。所有这些因素导致与未经设计的聚合物相比，电导率和 PF 都显著提高了三个数量级。结果表明，适当的供体工程可以提高 D-A 共聚物的 n 型掺杂效率、电导率和热电性能。
