小分子掺杂聚3,4-乙烯二氧噻吩基量子点复合薄膜的合成和热电性能研究

Conducting polymer thermoelectric materials possess the advantages such as flexibility and cheapness. However, owing to their low Seebeck coefficient, the performance cannot reach the application standard. Synthesizing organic-inorganic nanocomposites that exhibit scattering effect and enhanced the Seebeck coefficient is an effective route to improve the thermoelectric performance of conducting polymers. Small-sized anion doped poly(3,4-ethylenedioxythiophene) (S-PEDOT) exhibits the best thermoelectric performance among polymer thermoelectric materials, which is an ideal matrix for nanocomposite. However due to the insoluble nature, it is difficult to form nanocomposite. This project aim to synthesize and characterize the thermoelectric performance of S-PEDOT-quantum dot composite films. Novel highly soluble multi-functional non-Ferric oxidants will be used to polymerize S-PEDOT through vapor phase polymerization. Meanwhile these oxidants can be in-situ reduced to < 10 nm quantum dot form. Therefore, one-step synthesis of S-PEDOT-quantum dot composite film can be realized. Through changing the ratio of various multi-functional oxidant the quantum dot composition can be tuned. Through introducing a certain proportion of Fe(III) oxidant, the quantum dot weight percentage and size can be tuned. Finally, through effect control of band structure as well as transport properties, high performance polymer-quantum dot composite film can be obtained.

导电聚合物热电材料具有柔性、低成本等优点，然而由于泽贝克系数偏低，其热电性能仍达不到应用的标准。通过有机-无机复合，利用纳米粒子的散射效应提升泽贝克系数，是提升聚合物热电材料热电性能的重要途径。小分子掺杂聚3,4-乙烯二氧噻吩（S-PEDOT）是目前性能最优异的聚合物热电材料，是十分理想的基体材料，而由于不溶不熔等特性难以制得复合薄膜材料。本项目提出S-PEDOT-量子点复合薄膜的制备和性能研究，拟通过研发新型高醇溶性多功能非铁盐氧化剂，采用气相聚合法，在聚合S-PEDOT的同时，氧化剂自身原位还原为粒径小于10纳米的量子点，从而实现一步合成S-PEDOT-量子点复合薄膜；通过将多功能氧化剂混合使用并控制配比，调控量子点组成，并通过添加一定比例的单功能铁盐氧化剂，调控量子点的含量和粒径，最终实现对能带结构、电传输性质的有效调控，获得热电性能优异的聚合物-量子点复合薄膜。

有机-无机复合是提升柔性聚合物热电材料热电性能的有效途径，而小分子掺杂聚3,4-乙烯二氧噻吩（S-PEDOT）是目前性能最优异的p型导电聚合物薄膜材料之一，由于制备工艺的限制，通常难以制得高性能的无机纳米粒子复合材料。本研究将非铁盐的金属盐类氧化剂应用于气相聚合反应（VPP[）中，采用一步法制得了S-PEDOT-无机金属量子点复合薄膜。在研究中，详细表征了副反应的发生机制，通过添加一定比例的铁盐氧化剂，有效抑制了副反应的发生，在薄膜中均匀生成了纯净的小粒径金属量子点，有效降低了载流子浓度，提升了迁移率和功率因子，其中S-PEDOT-Ag量子点复合薄膜的在Ag量子点的含量低至0.2 wt%的情况下，室温下功率因子打到63.1μW/mK2，是目前已知的聚合物-金属纳米复合材料中的最高值。. 本项目对聚噻吩复合薄膜的研究，具有创新性。不仅在工艺上突破了S-PEDOT基复合薄膜制备的难点，还详细探讨了金属量子点对于薄膜热电性能的影响，有利于对于此类材料电输运性能的更深入理解，从而有望在后续研究中得到更高性能的有机-无机复合材料，进而推进导电聚合物热电材料的发展和应用。