塞贝克系数
热电效应
兴奋剂
三元运算
化学
电子能带结构
带隙
密度泛函理论
凝聚态物理
杂质
电阻率和电导率
电子结构
态密度
黄铜矿
电子迁移率
热电材料
铜
计算化学
热力学
物理
有机化学
量子力学
计算机科学
程序设计语言
作者
Hongyao Xie,Yukun Liu,Yinying Zhang,Shiqiang Hao,Zhi Li,Matthew Cheng,Songting Cai,G. Jeffrey Snyder,Chris Wolverton,Ctirad Uher,Vinayak P. Dravid,Mercouri G. Kanatzidis
摘要
The understanding of thermoelectric properties of ternary I-III-VI2 type (I = Cu, Ag; III = Ga, In; and VI = Te) chalcopyrites is less well developed. Although their thermal transport properties are relatively well studied, the relationship between the electronic band structure and charge transport properties of chalcopyrites has been rarely discussed. In this study, we reveal the unusual electronic band structure and the dynamic doping effect that could underpin the promising thermoelectric properties of Cu1-xAgxGaTe2 compounds. Density functional theory (DFT) calculations and electronic transport measurements suggest that the Cu1-xAgxGaTe2 compounds possess an unusual non-parabolic band structure, which is important for obtaining a high Seebeck coefficient. Moreover, a mid-gap impurity level was also observed in Cu1-xAgxGaTe2, which leads to a strong temperature-dependent carrier concentration and is able to regulate the carrier density at the optimized value for a wide temperature region and thus is beneficial to obtaining the high power factor and high average ZT of Cu1-xAgxGaTe2 compounds. We also demonstrate a great improvement in the thermoelectric performance of Cu1-xAgxGaTe2 by introducing Cu vacancies and ZnTe alloying. The Cu vacancies are effective in increasing the hole density and the electrical conductivity, while ZnTe alloying reduces the thermal conductivity. As a result, a maximum ZT of 1.43 at 850 K and a record-high average ZT of 0.81 for the Cu0.68Ag0.3GaTe2-0.5%ZnTe compound are achieved.
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