First Principles Calculations of Structural, Electronic, Mechanical, and Optical Properties of Tetra Potassium Diarsenido Zincate (K4znas2) Pnictide Ternary Semiconductor

Abstract

The scientific search for materials with good light energy absorption and desirable optical and electrical properties for applications in the areas of optoelectronics like photovoltaic is on the rise globally. Since the optoelectronic potential, intrinsic stability, eco-friendliness and conversion efficiency of most classes of semiconductor materials are not well researched, there is a need for an extensive study to provide an insight and the comprehensive properties of all classes of semiconductor compounds. This motivated us to perform ab initio DFT calculations based on plane wave self-consistent field technique for structural, electronic, mechanical, elastic, and optical properties using two exchange correlation functionals: the LDA and the GGA. The one based on LDA was Perdew-Zunger while those based on the GGA were Becke-Lee-Yang-Parr, Engel-Vosko, Perdew-Burke-Ernzerhof, Perdew-Burke-Ernzerhof for solids and Second-order correlations. The bandgap of the material was from the range of 0.5493 eV to 1.2282 eV, suggesting that the band gap is within the visible region. This indicates that the material is suitable for optoelectronic application in photovoltaic. The analysed electronic structure of the projected density of states using the PAW pseudopotentials displayed that the valence band was mainly dominated by As 2p, Zn 2p, Zn 1s, and K 2s, with other orbitals giving a very minimal contributions, whereas the conduction band of the material was mainly dominated by Zn 1s and Zn 2p, with small contributions from As 2p and K 2s orbitals, with the other orbitals making insignificant contributions. The most important and fundamental conditions for the elastic stability of rhombohedra lattice was satisfied. The optical properties displayed the material to have an excellent absorption of light energy within the visible region, which supports the results obtained for the band gap. The average lattice parameter was a = 18.2477, which is comparable with the one in the experimental results indicated in the open literature. The bulk moduli values of the six exchange correlations ranged from 13.3GPa-22.2GPa. The Young Moduli values ranged from 19.1GPa-20.9GPa. The Shear moduli values ranged from 7.4GPa- 7. 8GPa.The poison’s ratios ranged from 0.26-0.28. This information suggests that the material is ductile, mechanically stable, ionic, and anisotropic when subjected to external forces