Exploring the exemplary electronic and optical nature in NaInX2 (X = S, Se and Te) ternary type chalcogenides materials: A GGA+U and hybrid functionals study

In this work, a systematic study is carried about electronic and optical properties of Indium-based ternary chalcogenides materials by using the well-known density functional theory. We employed the GGA ​+ ​U and the hybrid functionals approach to consider the effects of on-site electron-electron interactions. A clear direct band gap nature was observed located at Γ-point showing all the three materials possess a direct band gap semiconductors nature. The In-s state signify smaller energy gap closer to high Γ-point symmetry. The Sodium ions in the materials are predominantly bonded ionically and there exists a covalent nature in the corresponding In–X (X ​= ​S, Se, Te) pairs. The optical parameters, were computed and are discussed in detail up to photon energy range of 14 ​eV. The first critical point related to the threshold energy in dielectric functions exist around the band gap, is due to the splitting which stretch threshold in term of direct optical transition between the valence band maxima and the conduction band minima. A sharp cut off response in absorption spectra at high energy value, confirms these materials as potential candidates in optoelectronic devices mainly operational in the UV region. The reflectivity spectra specify anisotropy and maximum peaks of about 70% at around 13.4 ​eV energy value making them promising shielding type material against the ultraviolet radiations. A substantial variation exists in the optical behavior of these studied materials which predicts that these calculations can lead to understand future theoretical and experimental investigations depending on the basic material properties of our studied materials as well as their applications specifically in optoelectronic devices. Real part of optical conductivity σxx(ω), σzz(ω) for NaInTe2 material. [Display omitted] •A clear direct band-gap is observed located at the Γ-point showing all the three materials to possess a direct band gap semiconductors nature.•The Na ions in these materials appear to be ionically bonded predominantly, whereas the covalency is strongly appears to exist in the In–X (X ​= ​S, Se, Te) pairs.•The portions of P-DOS near the Fermi energy were instigating principally due to the relatively localized In-p state and very sharp X-p states and the σs−p bonding character is most likely responsible in this valence band region.•The dispersion spectra ε1xx(ω), ε1zz(ω) and ε2xx(ω), ε2zz(ω) clearly signify the variation of imaginary part which is the abso