Department of Materials Science and Engineering, Johns Hopkins University , 3400 North Charles Street, Baltimore, Maryland 21218, United States.
Department of Mechanical and Aerospace Engineering, University of Virginia , Charlottesville, Virginia 22904, United States.
J Am Chem Soc. 2017 Aug 16;139(32):11149-11157. doi: 10.1021/jacs.7b05300. Epub 2017 Aug 7.
Four p-type polymers were synthesized by modifying poly(bisdodecylquaterthiophene) (PQT12) to increase oxidizability by p-dopants. A sulfur atom is inserted between the thiophene rings and dodecyl chains, and/or 3,4-ethylenedioxy groups are appended to thiophene rings of PQT12. Doped with NOBF4, PQTS12 (with sulfur in side chains) shows a conductivity of 350 S cm, the highest reported nonionic conductivity among films made from dopant-polymer solutions. Doped with tetrafluorotetracyanoquinodimethane (F4TCNQ), PDTDE12 (with 3,4-ethylenedioxy groups on thiophene rings) shows a conductivity of 140 S cm. The converse combinations of polymer and dopant and formulations using a polymer with both the sulfur and ethylenedioxy modifications showed lower conductivities. The conductivities are stable in air without extrinsic ion contributions associated with PEDOT:PSS that cannot support sustained current or thermoelectric voltage. Efficient charge transfer, tighter π-π stacking, and strong intermolecular coupling are responsible for the conductivity. Values of nontransient Seebeck coefficient and conductivity agree with empirical modeling for materials with these levels of pure hole conductivity; the power factor compares favorably with prior p-type polymers made by the alternative process of immersion of polymer films into dopant solutions. Models and conductivities point to significant mobility increases induced by dopants on the order of 1-5 cm V s, supported by field-effect transistor studies of slightly doped samples. The thermal conductivities were in the range of 0.2-0.5 W m K, typical for conductive polymers. The results point to further enhancements that could be obtained by increasing doped polymer mobilities.
四种 p 型聚合物通过修饰聚（双十二烷基噻吩）（PQT12）来增加 p 型掺杂剂的氧化能力而合成。在噻吩环和十二烷基链之间插入一个硫原子，和/或在 PQT12 的噻吩环上附加 3,4-亚乙基二氧基基团。用 NOBF4 掺杂后，具有侧链硫的 PQTS12 的电导率为 350 S cm，这是报道的掺杂聚合物溶液制成的薄膜中最高的非离子电导率。用四氟四氰基对醌二甲烷（F4TCNQ）掺杂时，具有噻吩环上 3,4-亚乙基二氧基基团的 PDTDE12 的电导率为 140 S cm。聚合物和掺杂剂的相反组合以及使用同时具有硫和亚乙基二氧基修饰的聚合物的配方显示出较低的电导率。在没有与 PEDOT:PSS 相关的外部离子贡献的情况下，电导率在空气中稳定，PEDOT:PSS 无法支持持续的电流或热电电压。有效的电荷转移、更紧密的π-π堆积和强分子间耦合是电导率的原因。非瞬态 Seebeck 系数和电导率的值与这些纯空穴电导率水平的材料的经验模型一致；与通过将聚合物薄膜浸入掺杂剂溶液中的替代工艺制造的先前 p 型聚合物相比，功率因子具有优势。模型和电导率表明，掺杂剂在 1-5 cm V s 的量级上引起了显著的迁移率增加，这得到了对稍微掺杂的样品的场效应晶体管研究的支持。热导率在 0.2-0.5 W m K 范围内，这是导电聚合物的典型范围。结果表明，通过增加掺杂聚合物的迁移率，可以进一步提高性能。
