In this work, we have studied the structural, optoelectronic, elastic and thermoelectric properties for halides doubles perovskites compounds K₂GeSiX₆ (X=F, Cl, Br and I). Based on the linearized augmented plane wave method with full potential (FP-LAPW) method, the previous properties are treated within GGA-PBE and the modified Beck–Johnson correction (mBJ-GGA) approximations. The results show that these compounds are stable in the nonmagnetic phase (NM). Due to the electronic properties, our results indicate that all these compounds have a semiconductor behavior with a direct bandgap at Γ-Γ direction with values of 2.30eV, 0.632eV, 0.259eV and 0.124eV for K₂GeSiF₆, K₂GeSiCl₆, K₂GeSiBr₆ and K₂GeSiI₆, respectively. In addition, the high dielectric constant, high absorption coefficient and high optical conductivity suggest that the materials have the potential for a wide absorption range that starts from the visible to the ultraviolet of optoelectronic applications, including solar or photovoltaic cells. Finally, the thermoelectric properties, through the calculation of the various related parameters (Seebeck coefficient, electrical conductivity, thermal conductivity, power factor and figure of merit), show that the materials K₂GeSiBr₆ and K₂GeSiI₆ can be promising for predispositions thermoelectric and by comparing the thermoelectric parameters of the two materials mentioned above, at room temperature, the material K₂GeSiI₆ has better performance than the material K₂GeSiBr₆, due to a significantly higher Seebeck coefficient (234.32μV/^°K), a fairly substantial power factor (1.17×1011Wk−2m−1s−1) and a fairly low thermal conductivity (0.48×1014WK−2m−1s−1).

中文翻译：

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半导体 K2GeSiX6（X=F、Cl、Br 和 I）化合物的电子结构和热电特性：Ab-Initio 研究

在这项工作中，我们研究了卤化物双钙钛矿化合物 K ₂ GeSiX ₆ (X=F、Cl、Br 和 I)。基于具有全势的线性增强平面波法（FP-LAPW）方法，在 GGA-PBE 和改进的贝克-约翰逊校正（mBJ-GGA）近似中处理了先前的属性。结果表明，这些化合物在非磁性相（NM）中是稳定的。由于电子特性，我们的结果表明所有这些化合物都具有半导体行为，在Γ-Γ值为 2.30 的方向电子伏特，0.632电子伏特，0.259eV 和 0.124分别为 K ₂ GeSiF ₆、K ₂ GeSiCl ₆、K ₂ GeSiBr ₆和 K ₂ GeSiI ₆的 eV。此外，高介电常数、高吸收系数和高光导率表明该材料具有从可见光到紫外光电子应用（包括太阳能或光伏电池）的宽吸收范围的潜力。最后，通过计算各种相关参数（塞贝克系数、电导率、热导率、功率因数和品质因数）的热电性能，表明材料K ₂ GeSiBr ₆和 K ₂ GeSiI ₆有望用于热电倾向，通过比较上述两种材料的热电参数，在室温下，材料 K _{2 GeSiI 6 比材料 K 2} GeSiBr _6具有更好_的性能，因为它具有显着更高的性能。塞贝克系数 (234.32μV/ ^° K），一个相当大的功率因数（1.17×1011周-2米-1s-1) 和相当低的热导率 (0.48×1014周刊-2米-1s-1）。