Ab-initio study about the electronic structure, optical, and transport properties of novel AIn2O4 (A = Ca, Sr, and Na) materials

Here, using first-principles calculations within the framework of density functional theory, we reported results relating to the structural stability, electronic, optical, and thermoelectric properties of AIn2O4 (A = Ca, Sr, and Na) spinel oxides. Among the three materials CaIn2O4, and NaIn2O4 have a direct bandgap semiconductor nature, whereas the SrIn2O4 shows an indirect bandgap semiconductor nature. These materials’ broad energy bandgaps reveal that the bonds present are strongly covalent in nature. The results of the band structures are also strongly supported by the calculated density of states for the three materials, which also validates their semiconducting nature. Our calculated density of states plots shows an overall similarity trend, indicating that the top of the valence bands in the CaIn2O4 materials originate primarily from the p-states and for SrIn2O4, and NaIn2O4 are due to the s-states of the oxygen anions. Additionally, the linear optical constants like the complex dielectric function, the refractive index, the electron energy loss function, the absorption coefficient, and the reflectivity spectra of these novel spinel oxides are computed and examined in detail for their possible applications in optoelectronic devices. The thermoelectric transport parameters were also calculated, and the findings obtained are presented in depth, indicating that these materials are suitable for thermoelectric device applications. Essentially, the present effort must assist the progress of discrete and integrated semiconductor device applications.