First-principles study of the electronic structure and optical properties of Eu2+ and Mn2+-doped NaLi3SiO4 phosphor

Abstract

Based on the plane-wave pseudopotential method of density functional theory, it calculates and compares the electronic structure and optical properties of NaLi₃SiO₄ before and after doping with Eu²⁺ and Mn²⁺. It investigates the feasibility of using Eu²⁺ and Mn²⁺-doped NaLi₃SiO₄ phosphor in the design of resin-phosphor-resin layered films for transparent display (TD) screens. The electronic structure analysis indicates that NaLi₃SiO₄ is an indirect bandgap compound with a bandgap value of 4.56 eV, capable of sustaining the energy difference between the ground state and the excited state of activator ions. Doping with Eu²⁺ and Mn²⁺ increases the crystal volume, reduces the bandgap, and results in a more compact band structure, making it easier for electrons to transition from the valence band to the conduction band. According to the optical properties analysis, NaLi₃SiO₄ is an excellent transparent material in visible and infrared light regions. Doping with Eu²⁺ and Mn²⁺ enhances the light absorption capacity of NaLi₃SiO₄ in the 0–5 eV energy range. Combined with its refractive index and reflectivity, it is evident that NaLi₃SiO₄: Eu²⁺ and NaLi₃SiO₄: Mn²⁺ phosphors exhibit good transparency in the visible light region. Therefore, they can become critical materials for designing resin–phosphor–resin layered films for TD screens.

Graphical abstract