电声相互作用对分子结热电输运性质的影响

项目名称： 电声相互作用对分子结热电输运性质的影响

项目编号： No.11304107

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 数理科学和化学

项目作者： 吕京涛

作者单位： 华中科技大学

项目金额： 25万元

中文摘要： 在线性输运情况下，材料的热电转换效率可以用ZT=S^2 G T/K来描述，其中S, G和K分别是材料的Seebeck系数，电导率和热导率。零维分子结结构是理想的热电材料，因为我们可以对以上参数进行相对独立的控制。当前的实验和理论研究着重于对这三个线性输运系数进行优化，但实际的热电器件都工作在非线性、非平衡态下。这时，器件的热电转换效率是否能够完全由ZT来描述仍有待研究。此外，同时存在温差和偏压情况下，非平衡电子和声子输运由于它们的相互作用而产生耦合。这一耦合不仅会对各自电导、热导产生影响，也会引入新的输运机制，比如电声子的相互拖曳效应。对于分子结结构中电声拖曳效应的研究几近空缺。本项目拟针对分子结器件，基于包含电声子相互作用的非平衡输运理论，对以上提及的问题展开从理论模型到第一性原理计算的多层次研究，以其进一步加深对低维体系非线性热电输运性质的理解。

中文关键词： 分子结；量子输运；热电效应；电声相互作用；

英文摘要： In linear transport regime, the dimensionless factor ZT=S^2 G T/K summaries the thermoelectric property of a material. Here S, G and K are the Seebeck coefficient, electrical and thermal conductivity, respectively. Zero-dimensional materials, like molecular junctions, are ideal candidates for thermoelectric applications,because it is possible to tune these transport coefficients independently in these structures. A great deal of effort has been focused on the optimization of these linear coefficients. But all the thermoelectric devices work in the nonlinear transport regime. It is not obvious that ZT alone can describe the thermoelectric efficiency of the device. On another aspect, in the presence of both temperature and voltage bias, nonequilibrium transport of electrons and phonons are coupled due to their mutual interactions. This will not only affect the aforementioned coefficients, but it will also introduce new transport mechanism, like electron or phonon drag effect. Experimental or theoretical study on this problem is rare. In this project, we will develop a nonequilibrium transport theory, including the electron-phonon interaction, to study these problems in molecular junctions. Through this study, we expect to gain more insight into the nonlinear thermoelectric transport properties in these low-dimensi

英文关键词： molecular junction；quantum transport；thermoelectric effect；electron-phonon interaction；