Bi2Te3基合金/石墨烯/PEDOT:PSS纳米复合块体材料的热电性能研究

The existing techniques to prepare Bi2Te3 based alloy/conducting polymer thermoelectric nanocomposites meet problems with poor dispersion of Bi2Te3 based alloy nanostructures in conducting polymer matrices and easy oxidation of Bi2Te3 based alloy nanostructures during the preparation of nanocomposites. As a result, the improvement of the thermoelectric properties for inorganic nanostructure/conducting polymer thermoelectric nanocomposites, and the application of thermoelectric devices were greatly restricted by these two main factors. However, so far, to the best of our knowledge, no effective method to solve these problems has been reported. .In this project, a new method will be used to preparation of ternary Bi2Te3 based alloy/graphene/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) thermoelectric nanocomposite. This ternary thermoelectric nanocomposite could have a higher TE properties, by taking advantages of the properties of Bi2Te3 based alloy (high Seebeck coefficient), graphene (high electrical conductivity), and PEDOT:PSS (low thermal conductivity) to potentially have a synergistic effect, when compared the traditional inorganic nanostructure/conducting polymer nanocomposites. The influencing factors of the thermoelectic properties for the Bi2Te3 based alloy/ graphene/PEDOT:PSS bulk nanocomposites will be illuminated. The transport rules and mechanisms of the carriers at different temperatures in the bulk nanocomposites will be also clarified. This project will create new knowledge on how to design and significantly improve the thermoelectric properties of inorganic nanostructure/conducting polymer thermoelectric nanocomposites, then lead to the development of unique, high-performance thermal-to-electrical energy harvesters for generation of electricity from various waste heat resources, and cooling devices.

传统的Bi2Te3基合金/导电聚合物纳米复合块体热电材料的制备方法容易产生以下两个问题: 1) Bi2Te3基合金纳米结构难于在导电聚合物基体中有效分散；2) Bi2Te3基合金纳米结构容易氧化。这两个问题限制了Bi2Te3基合金/导电聚合物纳米复合材料热电性能的提高和热电器件的实用化。至今仍未有很好的解决方案。本课题将首次设计和采用全新的方法制备三元Bi2Te3基合金/石墨烯/PEDOT:PSS纳米复合块体热电材料。该材料能充分发挥Bi2Te3基合金(高Seebeck系数)、石墨烯(高电导率)和PEDOT:PSS(低热导率)各自的优点，产生协同效应，实现热电性能的突破。通过本课题的实施，将进一步揭示影响复合块体材料热电性能的因素，以及不同温度下复合块体材料中载流子的输运规律及输运机制，获得高性能和低密度的复合块体热电材料，加速有机-无机纳米复合热电材料在热电发电和制冷器件上的应用。

本项目首次设计和采用全新的方法制备三元Bi2Te3基合金/石墨烯/PEDOT:PSS纳米复合块体热电材料。揭示了水热合成法制备Bi2Te3基合金/石墨烯纳米复合结构、热压烧结法制备Bi2Te3基合金/石墨烯纳米复合块体材料的最佳工艺条件；揭示了内部含三维多孔道交互联通的Bi2Te3基合金/石墨烯复合块体材料骨架的制备方法；通过六种不同的工艺探索了将PEDOT:PSS注入Bi2Te3基合金/石墨烯复合材料骨架的方法，揭示了PEDOT:PSS注入方式和含量对Bi2Te3基合金/石墨烯/PEDOT:PSS复合块体材料的组成和微观结构的影响规律；研究了不同温度条件下Bi2Te3基合金/石墨烯/PEDOT:PSS复合块体材料的热电性能，揭示了不同温度条件下复合块体材料中载流子的输运规律和机制。研究发现随着测试温度从300K增加到398K，通过优化PEDOT:PSS的注入工艺，Bi2Te3基合金/石墨烯/PEDOT:PSS复合块体材料的电导率逐渐下降，Seebeck系数的绝对值逐渐增大，热导率逐渐降低，复合材料的ZT显著升高。随着造孔时造孔剂含量从10%增加到30%，去除造孔剂并用PEDOT:PSS填充后的复合块体材料的电导率显著下降，Seebeck系数的绝对值呈现出上升趋势，功率因子显著下降。合成复合材料纳米结构过程中加入适量巯基丙酸，有利于进一步提高复合块体材料的热电性能。通过优化实验条件，所制备的Bi2Te3基合金/石墨烯/PEDOT:PSS复合块体材料在125ºC时的ZT值最大约为0.46。揭示了Bi-Te基合金纳米薄片/PEDOT:PSS复合薄膜材料的制备工艺，Bi-Te基合金纳米薄片含量为10%的复合薄膜在温度为380K时最高功率因子为58.9 μWm-1K-2。由5个单元的上述复合薄膜通过银胶首尾连接起来制备的热电器件，在温差为47.2K时的最大输出功率为16.9nW。研究了冷压工艺制备石墨烯/Bi2Te3/PEDOT纳米复合材料的热电性能，所制备的复合材料的在360K时最大功率因子为48 μWm-1K-2。研究了不同温度条件下石墨/PEDOT和石墨烯/聚吡咯纳米线复合材料的热电输运性能，以及无机相含量对上述复合材料热电性能的影响规律。本项目的开展有利于加速有机-无机纳米复合热电材料在热电器件上的应用，对该研究领域的研究具有重要意义和参考价值。