Electrostatic control of thermoelectricity in molecular junctions
Electrostatic control of thermoelectricity in molecular junctions
复制标题
DOI：
10.1038/nnano.2014.209
复制
发表时间：
2014-11-01
影响因子：
38.3
通讯作者：
Reddy, Pramod
中科院分区：
文献类型：
--
作者：
Kim, Youngsang;Jeong, Wonho;Reddy, Pramod
分子结对于高效和高功率输出的热电能量转换具有重要的前景（1-3）。最近的实验已经探索了分子结的热电性质（4-7）。然而，由于在三端器件中产生温差的技术挑战，通过栅电极对热电性质的静电控制是不可能的。在这里，我们表明，极大的温度梯度（超过1 × 10（9）Km（-1）），可以建立在纳米级的间隙分子桥接，同时通过栅极控制其电子结构。利用这个平台，我们研究了典型的Au-联苯-4，4 '-二硫醇-Au和Au-富勒烯-Au结，证明了通过静电控制可以同时提高分子结的塞贝克系数和电导。此外，从我们的研究富勒烯结，我们表明，热电性能可以显着增强时，占主导地位的运输轨道位于接近的化学势（费米能级）的电极。这些结果说明了分子结的热电性能和电荷传输特性之间的密切关系，应该能够系统地探索最近的计算预测1 -3，承诺非常有效的热电能量转换的分子结。
Molecular junctions hold significant promise for efficient and high-power-output thermoelectric energy conversion(1-3). Recent experiments have probed the thermoelectric properties of molecular junctions(4-7). However, electrostatic control of thermoelectric properties via a gate electrode has not been possible due to technical challenges in creating temperature differentials in three-terminal devices. Here, we show that extremely large temperature gradients (exceeding 1 x 10(9) Km(-1)) can be established in nanoscale gaps bridged by molecules, while simultaneously controlling their electronic structure via a gate electrode. Using this platform, we study prototypical Au-biphenyl-4,4'-dithiol-Au and Au-fullerene-Au junctions to demonstrate that the Seebeck coefficient and the electrical conductance of molecular junctions can be simultaneously increased by electrostatic control. Moreover, from our studies of fullerene junctions, we show that thermoelectric properties can be significantly enhanced when the dominant transport orbital is located close to the chemical potential (Fermi level) of the electrodes. These results illustrate the intimate relationship between the thermoelectric properties and charge transmission characteristics of molecular junctions and should enable systematic exploration of the recent computational predictions1-3 that promise extremely efficient thermoelectric energy conversion in molecular junctions.