Enlightening the stability and optoelectronic properties of Ba2MLnSe5 (M = Ga, In; Ln = Y, Nd, Sm, Gd, Dy, Er) semiconductors: A first-principles study

Emerging materials for optoelectronic and sustainable energy applications include chalcogenide materials. Therefore, using density functional theory and WIEN2k code, we investigated the electrical and optical properties of Ba2MLnSe5 (M = Ga, In; Ln = Y, Nd, Sm, Gd, Dy, Er). In GGA + U approximation, the band gaps for Ba2MLnSe5 (M = Ga, In; Ln = Y, Nd, Sm, Gd, Dy, Er) are calculated to be from 1.95 to 2.31 eV. Full geometric optimization was performed on the base of cell parameters. The obtained results indicated the overall semiconducting nature of Ba2MLnSe5 (M = Ga, In; Ln = Y, Nd, Sm, Gd, Dy, Er). From the electronic charge density study, we confirmed that the character of the investigated compound is mainly covalent. The top of the valence bands and the bottom of the conduction bands are due to Ba-d orbitals with minor contributions of Ga-p/d, Se-p/ d orbitals and M-d (M = Ga, In; Ln) states. Finally, we predicted the optical properties, such as the dielectric function, optical conductivity, refractive index, extinction coefficient, absorption coefficient, reflectivity coefficient, and loss function for polarized incident radiation with electrical vector E parallel to the crystalline axes a and c. Remote sensing and surgical equipment become more important due to the minimal reflection and maximal absorption of light in the infrared to the visible area. The resulting results are consistent with the experimental and theoretical data that is currently accessible. '