Oligoyne Molecular Junctions for Efficient Room Temperature Thermoelectric Power Generation
Oligoyne Molecular Junctions for Efficient Room Temperature Thermoelectric Power Generation
复制标题
DOI：
10.1021/acs.nanolett.5b03033
复制
发表时间：
2015-11-01
期刊：
影响因子：
10.8
通讯作者：
Lambert, Colin J.
中科院分区：
文献类型：
--
作者：
Sadeghi, Hatef;Sangtarash, Sara;Lambert, Colin J.
在分子尺度上理解声子输运是开发高性能热电材料将废热转化为电能的基础。我们研究了各种长度的烷烃和低聚炔链中的声子和电子输运，发现由于后者的刚性更大，低聚炔的声子热导率比相应的烷烃的声子热导率低。低聚炔的热导率随长度的增加而单调下降，而烷烃的热导率则先随长度的增加而增加，然后减小。这种行为上的差异源于金电极对声子的过滤，而当使用更高频率的德拜电极时，这种差异就消失了。因此，更好地传输高频声子模式的分子，与过滤高能声子的低德拜频率电极相结合，是抑制声子通过分子结传输的可行策略。低聚炔的低热导率，结合其较高的热电势和较高的电导率导致ZT = 1.4的最大热电优值，这比烷烃高几个数量级。
Understanding phonon transport at a molecular scale is fundamental to the development of high-performance thermoelectric materials for the conversion of waste heat into electricity. We have studied phonon and electron transport in alkane and oligoyne chains of various lengths and find that, due to the more rigid nature of the latter, the phonon thermal conductances of oligoynes are counterintuitively lower than that of the corresponding alkanes. The thermal conductance of oligoynes decreases monotonically with increasing length, whereas the thermal conductance of alkanes initially increases with length and then decreases. This difference in behavior arises from phonon filtering by the gold electrodes and disappears when higher-Debye-frequency electrodes are used. Consequently a molecule that better transmits higher-frequency phonon modes, combined with a low-Debye-frequency electrode that filters high-energy phonons is a viable strategy for suppressing phonon transmission through the molecular junctions. The low thermal conductance of oligoynes, combined with their higher thermopower and higher electrical conductance lead to a maximum thermoelectric figure of merit of ZT = 1.4, which is several orders of magnitude higher than that of alkanes.