单分子结中光电、光热输运性质的理论研究

The most important property of single molecular junction is its transport property. Recent experimental progress has made it possible to study not only its electrical transport, but also its thermal and optical properties. Actually, the nanoscale gap between metal electrodes of a single molecular junction supports highly localized plasmon modes, which have become one of the most important systems studied in the field of nano-plasmonics. The interaction between single molecule and the localized plasmon modes has important effect on the electrical and optical properties of the single molecular junction. In this project, from the charge and energy transport points of view, we will study the electrical current induced optical processes and the electrical transport properties driven by external optical fields. We combine transport theory based on nonequilibrium Green’s functions with numerical calculations based on density function theory for electronic structure and (semi-)classical electromagnetism for the optical property. It is hoped that our study can deepen our understanding of relevant experimental results, and be helpful for further advances in this field.

单分子的输运性质是分子电子学研究的核心问题。近年的实验进展使人们把研究的问题从单一的电学输运拓展到了热电、光电输运等。此外，单分子结的两个金属电极之间的纳米缝隙间存在高度局域的纳米等离激元模式，因此已经成为研究纳米等离激元的理想结构。单分子与局域等离激元模式的相互作用对于单分子结的电学输运及光学响应等性质有重要的影响。本项目拟从电荷、能量输运的角度来研究单分子结电流激发的光学响应特性以及在外加电磁场驱动下的电、热输运性质。我们把基于非平衡格林函数的输运理论与基于密度泛函理论的电子结构计算以及经典/半经典的电磁学数值模拟相结合来研究其光、电及能量输运性质，以期加深对相关实验现象的理解，促进该方向的发展。

单分子的输运性质是分子电子学研究的核心问题。通过本项目的研究我们把关注的问题从单一的电学输运拓展到了热电、光电输运性质。我们重点研究了单分子与局域等离激元模式的相互作用对单分子结的电学及发光性质的影响。从电荷、能量输运的角度,我们研究了利用电场和光场对分子及等离激元发光统计性质的调控，研究了库仑涨落及电子隧穿同时存在时纳米隧道结的热导对电极间距离的依赖关系等。我们基于非平衡格林函数方法的输运理论为理解这些物理性质提供了基本理论框架，为进一步加深对相关实验结果的理解，促进该方向的发展奠定了理论基础。