High thermoelectric power factor in two-dimensional crystals of MoS2
High thermoelectric power factor in two-dimensional crystals of MoS2
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DOI：
10.1103/physrevb.95.115407
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发表时间：
2017-03-03
影响因子：
3.7
通讯作者：
Zhang, Xiang
中科院分区：
文献类型：
--
作者：
Hippalgaonkar, Kedar;Wang, Ying;Zhang, Xiang
对高效热电转换的追求一直是未来可再生能源生产的主要驱动力之一。高效的热电装置需要从温度梯度产生高电压和大的电导率，同时保持低的热导率。对于给定的热导率和温度，热电功率因数由材料的电子结构决定。由于受限电子和空穴的独特态密度（DOS），低维（1D和2D）为高功率因数开辟了新的途径。2D过渡金属二硫属化物（TMDC）半导体代表了一类新型热电材料，不仅因为这种限制效应，而且特别是因为它们的大有效质量和谷简并性。在这里，我们报告的二硫化钼的功率因数高达8.5 mW m（-1）K-2在室温下，这是在传统的，有间隙的热电材料中测得的最高。为了获得这些高功率因数，我们在金属制度，这使我们能够访问导带边缘附近的2D DOS和利用2D限制对电子散射率的影响，导致在一个大的塞贝克系数的几层二硫化钼上进行热电测量。2D TMDC中已证明的高电子调制功率因子为高效的热电能转换带来了希望。
The quest for high-efficiency heat-to-electricity conversion has been one of the major driving forces toward renewable energy production for the future. Efficient thermoelectric devices require high voltage generation from a temperature gradient and a large electrical conductivity while maintaining a low thermal conductivity. For a given thermal conductivity and temperature, the thermoelectric power factor is determined by the electronic structure of the material. Low dimensionality (1D and 2D) opens new routes to a high power factor due to the unique density of states (DOS) of confined electrons and holes. The 2D transition metal dichalcogenide (TMDC) semiconductors represent a new class of thermoelectric materials not only due to such confinement effects but especially due to their large effective masses and valley degeneracies. Here, we report a power factor of MoS2 as large as 8.5 mW m(-1) K-2 at room temperature, which is among the highest measured in traditional, gapped thermoelectric materials. To obtain these high power factors, we perform thermoelectric measurements on few-layer MoS2 in the metallic regime, which allows us to access the 2D DOS near the conduction band edge and exploit the effect of 2D confinement on electron scattering rates, resulting in a large Seebeck coefficient. The demonstrated high, electronically modulated power factor in 2D TMDCs holds promise for efficient thermoelectric energy conversion.