First-Principles Investigation of Electronic Structure and Energy Level Scheme of Phosphors: The Lanthanide-Doped Sr2P2O7

Using screened hybrid density functional theory (HSE06), the electronic structure, character of electronic transition and energy level scheme of lanthanide (Ln)-doped Sr 2 P 2 O 7 are systematically investigated. Both Ln 2+ and Ln 3+ dopants are considered. It is found that, owing to the doping of Ln 2+/3+ ions, some extra Ln 4 f and 5 d states are introduced in the host Sr 2 P 2 O 7 band gap, causing a change in the electronic structures and the luminescence properties. The specific locations of the Ln 4 f and 5 d states and the possibility of electronic transitions, especially the 4 f → 5 d , are systematically studied. The energy level scheme is constructed from the calculated electronic structures, and it fits well with the experimental scheme. This work gives a whole picture of the Ln doping effect on the materials. It can be applied to all Ln-doped fluorescent materials and to aid in the discovery of new bright scintillator materials.