Effect of Coulomb interactions on optoelectronic properties of Eu doped lanthanide stannates pyrochlore: DFT ​+ ​U investigations

Abstract

In optoelectronics, the perovskite structures in layered form, also called pyrochlore have been demonstrated to be very largely favorable to the insertion of lanthanides ions, which led them to create new phosphor emitting in a broad spectral range going from visible to near infrared. The pyrochlore oxides such as La2Sn2O7 have attained much interest due to their electronic and optical properties. In the present work, we used first-principle calculations to compute the electronic band structure and related optical properties for pure La2Sn2O7 and La2Sn2O7 doped with europium. Spin orbit coupling (SOC) and electron-electron interaction, both within the generalized gradient approximation plus Hubbard parameter U (SOC ​+ ​GGA ​+ ​U) approximations have been used within the framework of density functional theory (DFT). It was found that La2Sn2O7 compound exhibits a direct band gap semiconductor with 2.7 ​eV. Doping of europium further decreases the band gap of pyrochlore of material up to 1.8 ​eV. Optical properties revealed that both compounds are potential materials for optoelectronic device fabrication.