Role of 4p-3d orbital hybridization on band gap engineering of heavy metal glass for optoelectronic applications

Abstract

Optoelectronic properties of glasses can be engineered by understanding the electronic structure and the symmetry of electronic states across the band gap where the chemical bonding is the origin of such electronic structure. Thus, series of heavy metal lead borate glasses of the composition 0.25B2O3–0.75PbO is prepared by melt quenching technique for Vis–IR photonics applications. Hybridization of p- and d-block elements, through co-substitution of Cr2O3 and SeO2, by B2O3, is used to tune effectively the glass electronic structure characteristics such as; band gap energy, Fermi level, and Urbach exciton–phonon coupling. Two-photon absorption coefficient is determined to elucidate the glass nonlinear sub-interband transitions. Chemical bond approach is applied to analyze and explain the obtained glass properties. The excitons excitation is discussed by applying Elliott’s model which indicates direct interband transition nature of the glass that is assisted by the existence of stable Frenkel excitons.