The current work analyzes the electronic, structural, mechanical, thermoelectric (TE), and optical properties of alkali-based transition metal chalcogenides ${\mathrm{A}}_2{\text{MoS}}_4$ (A = K, Rb, Cs) and ${\text{Cs}}_2{\text{MoSe}}_4$ using methods based on first principles. The electronic, structural, and mechanical properties are analyzed using projected augmented wave (PAW) potentials. The electronic structure calculations show them to be direct bandgap semiconductors. From the TE properties, it is found that all the compounds possess huge thermopower especially for the holes, and this along with low lattice thermal conductivity enables us to predict ${\mathrm{A}}_2{\text{MoS}}_4$ (A = K, Rb, Cs) and ${\text{Cs}}_2{\text{MoSe}}_4$ to be a good class of material for TE applications. Also, the optical properties are found to be nearly isotropic in the low energy region, which also might fetch potential applications in the visible range. The nearly isotropic optical properties along with giant thermopower are the highlights of the current study, which sets a platform for exploring future device applications.

中文翻译：

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A2MoS4 (A = K, Rb, Cs) 和 Cs2MoSe4 的高热功率和光学性能

目前的工作分析了碱基过渡金属硫属元素化物的电子、结构、机械、热电 (TE) 和光学性质 ${\mathrm{一种}}_2{\text{硫化钼}}_4$ (A = K, Rb, Cs) 和 ${\text{CS}}_2{\text{钼}}_4$使用基于第一性原理的方法。使用投影增强波 (PAW) 电位分析电子、结构和机械特性。电子结构计算表明它们是直接带隙半导体。从 TE 特性中，发现所有化合物都具有巨大的热电势，尤其是对于孔洞，这与低晶格热导率一起使我们能够预测${\mathrm{一种}}_2{\text{硫化钼}}_4$ (A = K, Rb, Cs) 和 ${\text{CS}}_2{\text{钼}}_4$成为 TE 应用的优质材料。此外，发现低能量区域的光学特性几乎是各向同性的，这也可能在可见光范围内获得潜在的应用。近乎各向同性的光学特性以及巨大的热电势是当前研究的亮点，为探索未来的设备应用奠定了平台。