First-principles study of elastic, electronic, optical and thermoelectric properties of newly synthesized K2Cu2GeS4 chalcogenide

Abstract

We report the first principles study of structural, elastic, electronic, optical and thermoelectric properties of newly synthesized K 2 Cu 2 GeS 4 . The structural parameters are found to be in good agreement with experimental results. The single crystal elastic constants (C ij ) are calculated and K 2 Cu 2 GeS 4 is found to be mechanical stable. The analysis of polycrystalline elastic constants reveals that the compound is expected to be soft in nature. The values of Pugh and Poisson ratios suggested that the compound lies in the border line of ductile/brittle behavior. The chemical bonding is primarily ionic, the inter-atomic forces are central in nature and the compound is mechanically anisotropic. The computed electronic band profile shows semiconducting characteristics and the estimated band gap is strongly dependent on the functional used representing the exchange correlations. The nature of chemical bonding is explained using electronic charge density mapping. Important optical constants such as dielectric constants, refractive index, absorption coefficient, photoconductivity, reflectivity and loss function are calculated and discussed in detail. Optical conductivity is found to be in good qualitative agreement with the results of band structure calculations. The Seebeck coefficients are positive for the entire temperature range used in this study, suggesting the presence of p-type charge carriers. We have obtained large Seebeck coefficent, 681 V/K at 100 K and 286 V/K at 300 K. At room temperature, the electrical conductivity and electronic thermal conductivity are 1.83×10 18 ms) -1 and 0.5×10 14 W/mK.s, respectively. The dimensionless figure of merit of K 2 Cu 2 GeS 4 is evaluated as ~1.0 at 300 K. This suggests that K 2 Cu 2 GeS 4 is a potential candidate for thermoelectric applications.

NaInX2 (X = S, Se) layered materials for energy harvesting applications: first-principles insights into optoelectronic and thermoelectric properties

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Newly Synthesized Three-Dimensional Boron-Rich Chalcogenides B12X (X = S and Se): Theoretical Characterization of the Physical Properties for Optoelectronic and Mechanical Applications

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Origin of high hardness and optoelectronic and thermo-physical properties of boron-rich compounds B6X (X = S, Se): A comprehensive study via DFT approach

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