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Ultralow lattice thermal conductivity and high thermoelectric performance of monolayer KCuTe: a first principles study

机译:Monolayer KCute的超级晶格导热系数和高温性能:第一个原理研究

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Monolayer KCuTe is a new-type of two-dimensional (2D) semiconductor material with high carrier mobility and large power energy conversion efficiencies, suggesting its potential application in thermoelectric (TE) and photoelectric fields. Based on the density functional theory (DFT) and semiclassical Boltzmann transport equation, the electronic and phonon transport properties of monolayer KCuTe are systematically studied. Our results show that it possesses an ultralow lattice thermal conductivity value of nearly similar to 0.13 W m(-1) K-1 at 300 K, mainly attributed to its small phonon group velocity, large Gruneisen parameters, and strong phonon-phonon scattering. Furthermore, the intralayer opposite phonon vibrations greatly restrict the heat transport. Monolayer KCuTe shows an ideal direct band gap of similar to 1.21 eV, and a high twofold degeneracy appearing at the Gamma point gives a high Seebeck coefficient of similar to 2070 mu V K-1, leading to high TE performance. Using the transport coefficients together with constant electron relaxation time, the figure of merit (ZT) can reach 2.71 at 700 K for the p-type doping, which is comparable to the well-known TE material SnSe (2.6 +/- 0.3 at 935 K). Our theoretical studies may provide perspectives to TE applications of monolayer KCuTe and stimulate further experimental synthesis.
机译:单层KCute是一种新型的二维(2D)半导体材料,具有高载流动性和大的功率转换效率,表明其在热电(TE)和光电场中的潜在应用。基于密度泛函理论(DFT)和半透明的Boltzmann传输方程,系统地研究了单层KCute的电子和声子传输性能。我们的结果表明,它具有几乎类似于0.13W m(-1)k-1的超级晶格导热率值,主要归因于其小的声子组速度,大的Gruneisen参数和强子源散射。此外,对立的声子位振动极大地限制了热传输。单层kcute显示出类似于1.21eV的理想直接带隙,并且在γ点出现的高双重退化使得具有与2070μmVk-1类似的高塞贝克系数,导致高TE性能。使用传输系数与恒定的电子松弛时间一起,优选(ZT)的数字可以在700 k处达到2.71,用于p型掺杂,其与众所周知的TE材料SNSE相当(在935处为2.6 +/- 0.3 k)。我们的理论研究可以为单层kcute的Te应用提供视角,并刺激进一步的实验合成。

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    《RSC Advances》 |2019年第62期|共7页
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  • 正文语种 eng
  • 中图分类 化学;
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