热电效应
热电材料
材料科学
热导率
各向异性
声子
非谐性
半导体
凝聚态物理
单层
塞贝克系数
功勋
光电子学
纳米技术
热力学
光学
物理
复合材料
作者
Tianqi Zhao,Yajing Sun,Zhigang Shuai,Dong Wang
标识
DOI:10.1021/acs.chemmater.7b01343
摘要
The successful demonstration of SnSe single crystals as promising thermoelectric materials highlights alternative strategies to nanostructuring for achieving high thermoelectric efficiency. It stimulates us to screen the periodic table for earth-abundant materials with layered crystal structures and intrinsically low thermal conductivity. GeAs2 is made from group IV and V elements within the same period as selenium, and it exhibits anisotropic and anharmonic bonding character similar to the IV–VI group compound SnSe. Here we present a theoretical investigation of the electronic structure, phonon dispersion, and electron–phonon couplings of monolayer GeAs2 to predict its electrical and thermal transport properties. GeAs2 features flat band and multivalley convergence that give rise to large Seebeck coefficients. Remarkably, monolayer GeAs2 demonstrates anisotropic and amazingly low lattice thermal conductivity of 6.03 W m–1 K–1 and 0.68 W m–1 K–1 at 300 K in the a and b directions, respectively, which we attribute to its soft vibrational modes and anomalously high Grüneisen parameter. The ultralow thermal conductivity leads to maximum thermoelectric figures of merit of 2.1 and 1.8 for n-type and p-type, respectively, at 900 K. These intriguing attributes distinguish GeAs2 from other 2D materials and make it a promising candidate for environmentally friendly thermoelectric applications.
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