First Principles Calculations of Structural, Electronic, Mechanical and Optical Properties of K2SbAu Pnictides Ternary Semiconductor

Abstract

The most active research currently in the field of semiconductors is the determination of the most efficient materials for application in photovoltaics and optoelectronics. Semiconductors compounds have attracted great attention, and the most interesting type is the ternary semiconductors whose potential has not been fully realized. The work being reported here studied the structural, electronic, mechanical, elastic and optical properties of K2SbAu pnictide ternary semiconductor.Density functional theory (DFT), a first-principles method, was employed to compute the structural, electronic, elastic and optoelectronic properties. Ground state structural properties were obtained using the generalized gradient approximation exchangecorrelation potential with ultrasoft Perdew-Burke-Enzerhof (PBE) and Perdew-Burke-Enzerhof for solids (PBEsol) as the exchange-correlation functionals. Another functional used was the Perdew-Zunger for the Local Density Approximation (LDA) exchange-correlation potential. The equilibrium lattice parameters were the key structural properties of the material derived from the computed equation of state (EOS). Moreover, mechanical stability was tested on elastic constants which were obtained to be 6.60149Ȧ for GGA , 6.19105 Ȧ for LDA and 6.39519 Ȧ for PBEsol. The deduced direct band gaps were obtained from the calculations as 0.9430 eV, 0.9060 eV, and 0.8482 eV for PBE, PBESol and LDA, respectively. In all cases, Au-3d orbitals were observed to be dominant at the top of the valence band. Lastly, frequency-dependent optical spectra were calculated with the aid of microscopic dielectric tensors. The optical properties were calculated as refractive index, absorption coefficient, energy loss, and reflectivity. The K2SbAu material optical bandgap on average was found to be 2.5 eV, suggesting that it can be a potential for solar photovoltaic applications.The results obtained were in agreement with the experimental values for structural properties, and this investigation should trigger further research interests to broaden the knowledge base on these materials from a theoretical perspective.