基于高导电碳纳米管/聚苯胺复合材料的热电性能优化研究

Carbon nanotubes (CNT) / Polyaniline (PANI) composites have attracted extensive attention as promising thermoelectric materials due to their advantages of excellent conductivity and facile synthesis,. At present, CNT/PANI films are prepared through the same procedures of pure PANI. Few studies have been conducted to optimize their morphology, structure, and electrical property, which limit the improvement of thermoelectric performance of the composites. Based on the highly conductive CNT/PANI composites (~ 3009 S cm-1), this project aims to improve thermoelectric performance of the composites by regulating the polymerization parameters and doping level. With modifying polymerization parameters (such as the concentration of aniline and the polymerization rate), the chain structure and crystallinity of PANI which wrapped on the surface of CNT can be optimized, and optimum carrier concentration and mobility of the composites can be achieved by tuning doping levels (modified via the content of dopant and base treatment to dedope). After that, the conductivity and Seebeck coefficient of the composites can be optimized simultaneously. Furthermore, the effect of polymerization parameters and doping levels will be investigated on how they can regulate the structure, morphology, electrical property, and thermoelectric performance of the composites. Meanwhile, the charge transport within the composites will be explored, and these studies will pave the way for the high performance organic thermoelectric composites.

碳纳米管（CNT）/聚苯胺（PANI）复合材料导电优良且易于制备，在热电领域引起广泛关注。但现阶段CNT/PANI热电器件的制备依照纯聚苯胺的制备工艺，缺乏对其形貌结构及电学性质的调控优化，影响其热电性能进一步提升。本项目以高导电CNT/PANI复合材料(~ 3009 S cm-1)为基础，提出调控聚合参数和掺杂度的方法提升复合材料的热电性能。通过调控聚合参数（包括单体浓度和聚合反应速度）优化CNT表面PANI的链结构和结晶性，同时调节掺杂度（调控掺杂剂含量和碱处理去掺杂）以调控其载流子浓度和迁移率，最终协同优化其电导率和塞贝克系数。系统研究聚合参数和掺杂度对复合材料的结构、形貌、电学性质和热电性能的影响规律，阐明复合材料两相间电荷传导机制，为有机复合热电材料的发展提供新思路。

通过在碳纳米管（CNTs）表面原位聚合生长聚苯胺（PANI）制备CNTs/PANI复合材料是开发柔性热电材料的有效途径，但其掺杂工艺及形貌结构缺乏调控优化，电荷输运机制尚不明确，制约其热电性能的提升。本项目通过调控聚合参数、掺杂度和界面结构调节PANI链段结构及复合材料形貌，探究其形貌结构-载流子输运特性-热电性能之间的关联，优化工艺参数实现电导率和塞贝克系数的协同优化，开发高热电性能CNTs/PANI复合材料。研究发现，高单体浓度和慢聚合速度有利于聚苯胺链段增长及结晶性提升，所制得聚苯胺及其复合材料热电性能最高。基于此，通过调节掺杂剂加入量和溶剂后处理（氨水和乙醇）工艺调控PANI掺杂度及电学性质，阐明复合材料电荷传导机制。CNTs导电网络结构及CNTs-PANI之间强π-π相互作用促使复合材料在低掺杂度下仍能保持较高的电荷传导，同时界面能量过滤效应有利于塞贝克系数的提升，最终其热电功率因子在较低掺杂度下达到最高。最后，通过去掺杂-再掺杂工艺调控界面结构，使其在保持高电导率的同时增强复合材料的界面能量过滤效应，进一步提升复合材料功率因子至407 μW m-1 K-2，为当前文献报道的CNTs/PANI体系热电性能最高值之一。该项目不仅为复合材料热电性能的提升提供了新的思路及研究基础，还开发出高热电性能有机复合材料，推动其在柔性热电器件的应用及发展。