新型N型硫化物Bi2SeS2热电输运特性及性能提高机理研究

热电材料在新能源领域具有重要的应用价值。得益于硫元素的廉价、低毒及环境友好性，硫化物体系热电材料的研究成为近几年来一个新兴的研究方向。然而，高的电阻率和低的热电优值成为大多数硫化物的共性问题。本项目基于传统材料性能增强的机理和制约硫化物性能提高的因素，选取与传统碲化铋材料具有相似性的新型三元硫化物Bi2SeS2为研究对象，系统而深入的探究其热电传输特性和性能提高机理。同时，在通过掺杂、晶粒细化、纳米第二相复合等传统手段优化性能的基础上提出有序化调控，以量化传统手段所形成的散射中心对电子和声子输运行为的影响，旨在保持对声子有效散射条件下重建电子的输运通道，获得热电优值大于1.2的高性能Bi2SeS2基硫化物热电材料，并总结出有利于声子散射和电子传输的普适规律，为发展高性能热电纳米复合材料提供新方向。

Thermoelectric materials have received more and more attention, because of their promising application in the field of new energy. Benefiting by the low cost, low toxicity and environmental friendliness of sulfur, more focuses are placed on sulfide compounds, which are explored as the alternative materials of traditional thermoelectric compounds. However, most sulfide compounds show poor electrical conductivity which induces in a low figure of merit. Actually, this dilemma exists in most environmentally friendly sulfide compounds so far. Based on the performance enhancement mechanism of traditional material and the factors restricting the performance improvement of sulfide compound, this topic selects a new ternary sulfide compound Bi2SeS2, which is a sulfide counterpart of the traditional material Bi2Te3, as the research object. The intrinsic electrical and thermal transport of Bi2SeS2 will be studied systemically with an emphasis on the influence of the doping and microstructure. Meanwhile, ordered nanostructure of doping, grains and nano second phase, in which the electron transport channel is intended to reconstructed without effecting the scattering of the phonons, will be further carried out to improve the thermoelectric property of Bi2SeS2 with a aim to developing a new type sulfide compound with a high figure of merit over 1.2. Furthermore, we will try to summarize the general law that can be conducive to the phonon scattering and electron transport during studying of the ordered nanostructure, which will provide a new direction for the development of high-performance thermoelectric nanocomposites.