A Comprehensive Investigation of Optoelectronic and Thermoelectric Attributes of VCu3X4 (X=S,Se,Te) Compounds for Renewable Energy Applications

Abstract

Abstract Research on sustainable, environmentally friendly power sources aims to address potential energy issues caused by the decreasing availability of renewable resources. The V-series compounds are considered the most promising materials for the next generation because they are ecologically friendly. In the present work, we used First-Principle computation to investigate the structural, mechanical, optical, electronic, thermodynamic, and thermoelectric attributes of VCu₃X₄ (X=S,Se,Te) compounds using Density Functional Theory (DFT). First, we applied the PBE-GGA method to calculate the lattice constants, which were found to be 5.437 Å, 5.669 Å, and 5.954 Å for VCu₃S₄, VCu₃Se₄, and VCu₃Te₄, respectively. We thoroughly examined the binding energy to assess the structural stability of VCu₃X₄ compounds, revealing the thermodynamical stability of the uunder-study compounds. Furthermore, mechanical stability was confirmed using elastic stiffness constants, satisfying the Born-Stability criteria (C_44<0). Pugh’s and Poisson’s ratios, along with the Cauchy pressure, indicated ductile behavior in all compounds except VCu₃S₄, which exhibited brittle characteristics. The compounds demonstrate significant optical conductivity and absorption coefficients, with VCu₃Te₄ being particularly responsive to intense photon streams due to its smaller band gap of 0.57 eV, while VCu₃S₄ and VCu₃Se₄ have band gaps of 1.01 eV and 0.88 eV, respectively. We assessed the electronic properties by examining the band structure and the total and partial density of states (TDOS/PDOS), which illustrated that the under studied compounds have indirect band gaps of 1.01 eV (VCu₃S₄), 0.88 eV (VCu₃Se₄), and 0.57 eV (VCu₃Te₄). Using BoltzTraP coding, we evaluated the Seebeck coefficient, electrical and thermal conductivity, and power factor, demonstrating that VCu₃Te₄, with its small energy gap, is particularly promising for high-temperature thermoelectric and optoelectronic applications.