SnSe气凝胶/PEDOT:PSS三维网络结构复合材料制备与热电性能研究

Inorganic/polymer based thermoelectric materials have attracted much attention due to their potential applications in the field of recovering low-grade waste heat. However, the ZT value of inorganic/polymer based materials has remained low, which limits their applications. The poor performance of such thermoelectrics can be ascribed to their low Seebeck coefficient. In this study, we provide a new strategy of constructing a three-dimensional network to improve theirs thermoelectric performance. The SnSe nanowires and poly(3,4-ethylenedioxythiophene): poly(styrenesulphonate) (PEDOT:PSS) will be used as raw material, and the SnSe nanowires are firstly assembled to aerogel, and then three-dimensional network SnSe aerogel/PEDOT:PSS composites are prepared by vacuum-impregnation process. This composite design can maintain the high conductivity though the rigid scaffold of the component and the interface of composites can effective increase the Seebeck coefficient by the carrier-filtering processes and reduce thermal conductivity due to enhanced phonon scattering. This design of high power factor, lower thermal conductivity and high thermoelectric performance inorganic/polymer can provide technical foundation for design and development of polymer based thermoelectric materials.

有机-无机复合热电材料可以在低品位热量回收方面具有广阔的应用前景，近年来受到了越来越大的关注。但是目前有机-无机复合热电材料的Seebeck系数偏低，热电性能较差，限制了它的实际应用。本项目拟设计一种新颖的具有三维网络结构的热电复合材料，来提高热电性能。以SnSe纳米线和聚(3,4-二氧乙撑噻吩):聚苯乙烯磺酸 (PEDOT:PSS)为原料，首先将SnSe纳米线组装成三维连通的气凝胶结构，然后采用真空浸渍方法，获得SnSe气凝胶/PEDOT:PSS复合结构，形成双重三维网络结构。该结构不仅有利于SnSe和PEDOT:PSS自身内部的载流子迁移，保证复合材料具有高的电导率，同时二者之间的界面同时起到能量过滤效应和散射声子的作用，达到提高Seebeck系数和降低热导率的效果。最终得到高功率因子、低热导率、高热电性能的新型热电复合材料，为热电复合材料成分设计、微观结构设计提供理论指导和科学依据。

导电高分子聚（3, 4-乙烯二氧噻吩）：聚苯乙烯磺酸（PEDOT:PSS）因其本征低热导率、高柔性及可调控的电子结构等优势，受到热电研究者的广泛关注。近年来，大量研究结果表明制备有机-无机复合材料可有效提升有机基体的热电性能，然而在实际研究中解耦热电复合材料各性能参数（电导率σ、Seebeck系数S与热导率κ）的关系依然存在巨大挑战。本项目以PEDOT:PSS为研究对象，选择不同的无机材料制成复合材料，通过制备工艺优化、结构（界面）设计、还原剂处理等方式来调控各PEDOT:PSS/无机复合体系的热电性能。首先选择细菌纤维素做基体制备具有多种孔结构的SWCNT/BC复合材料， PEDOT/SWCNT/BC和PEDOT@BC/SWCNT复合薄膜，探究多孔结构、SWCNT含量和复合方式对热电性能性能的影响。研究表明PEDOT@BC/SWCNT复合薄膜与PEDOT/SWCNT/BC复合薄膜相比，电导率没有发生降低，但PEDOT@BC/SWCNT复合薄膜的赛贝克系数随SWCNT含量增加而增加，在SWCNT含量达70%时，最大的ZT为0.13，并且复合薄膜在200次弯折测试过程中性能未降低，具有较好的柔性。通过构筑多重界面共存的三元复合体系，实现了热电性能的综合提升（ZT = 0.24）；同时对复杂有机无机纳米体系中的界面问题进行深入探究，利用新的表征手段和理论系统解析了界面对电、热传输性能的影响；最后制备的柔性热电器件展现出极具竞争力的性能，为未来材料应用于可穿戴器件奠定基础。