A comprehensive investigation of optoelectronic and thermoelectric attributes of VCu3X4 (X = S,Se,Te) compounds for renewable energy applications

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 VCu ₃ X ₄ ( 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 VCu ₃ S ₄ , VCu ₃ Se ₄ , and VCu ₃ Te ₄ , respectively. We thoroughly examined the binding energy to assess the structural stability of VCu ₃ X ₄ 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 VCu ₃ S ₄ , which exhibited brittle characteristics. The compounds demonstrate significant optical conductivity and absorption coefficients, with VCu ₃ Te ₄ being particularly responsive to intense photon streams due to its smaller band gap of 0.57 eV , while VCu ₃ S ₄ and VCu ₃ Se ₄ 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 ( VCu ₃ S ₄ ) , 0.88 eV ( VCu ₃ Se ₄ ) , and 0.57 eV ( VCu ₃ Te ₄ ) . Using BoltzTraP coding, we evaluated the Seebeck coefficient, electrical and thermal conductivity, and power factor, demonstrating that VCu ₃ Te ₄ , with its small energy gap, is particularly promising for high-temperature thermoelectric and optoelectronic applications.