Department of Mechanical Engineering, Texas A&M University, College Station, Texas 77843, United States.
ACS Nano. 2011 Oct 25;5(10):7885-92. doi: 10.1021/nn202868a. Epub 2011 Sep 19.
Typical organic materials have low thermal conductivities that are best suited to thermoelectrics, but their poor electrical properties with strong adverse correlations have prevented them from being feasible candidates. Our composites, containing single-wall carbon nanotubes, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) and/or polyvinyl acetate, show thermopowers weakly correlated with electrical conductivities, resulting in large thermoelectric power factors in the in-plane direction of the composites, ∼160 μW/m·K(2) at room temperature, which are orders of magnitude larger than those of typical polymer composites. Furthermore, their high electrical conductivities, ∼10(5) S/m at room temperature, make our composites very promising for various electronic applications. The optimum nanotube concentrations for better power factors were identified to be 60 wt % with 40 wt % polymers. It was noticed that high nanotube concentrations above 60 wt % decreased the electrical conductivity of the composites due to less effective nanotube dispersions. The thermal conductivities of our 60 wt % nanotube composites in the out-of-plane direction were measured to be 0.2-0.4 W/m·K at room temperature. The in-plane thermal conductivity and thermal contact conductance between nanotubes were also theoretically estimated.
典型的有机材料具有较低的热导率，最适合用于热电领域，但由于其较差的电性能与强烈的负相关性，使其无法成为可行的候选材料。我们的复合材料，包含单壁碳纳米管、聚(3,4-亚乙基二氧噻吩):聚(苯乙烯磺酸盐)和/或聚醋酸乙烯酯，表现出与电导率弱相关的热功率，从而在复合材料的面内方向产生大的热电功率因子，在室温下约为 160 μW/m·K(2)，比典型的聚合物复合材料大几个数量级。此外，其高电导率，室温下约为 10(5) S/m，使我们的复合材料非常适合各种电子应用。确定了用于获得更好功率因子的最佳纳米管浓度为 60wt%的纳米管与 40wt%的聚合物。人们注意到，高于 60wt%的高纳米管浓度会由于纳米管分散效果较差而降低复合材料的电导率。我们的 60wt%纳米管复合材料在面外方向的热导率在室温下测量为 0.2-0.4 W/m·K。还对纳米管之间的面内热导率和热接触电导进行了理论估计。
