Synthesis, luminescence properties and energy transfer of Ca2MgWO6:Cr3+,Yb3+ phosphors

Abstract

An efficient near-infrared phosphor Ca2MgWO6:Cr3+,Yb3+ has been successfully prepared by solid state reaction in air. After co-doping with Cr3+ ion, Ca2MgWO6:Yb3+ can be efficiently excited by broadband UV light due to Cr3+:4A2→4T1(4P) transition, and give intense near-infrared emission at ∼980 nm owing to the effectively sensitized Yb3+:2F5/2→2F7/2 transition. Energy transfer from Cr3+ ion to Yb3+ ion in Ca2MgWO6 host was demonstrated to be mainly a resonant type via dipole-dipole mechanism, accompanied by a degree of down conversion process. The energy transfer efficiency from Cr3+ ion to Yb3+ ion was determined and the possible energy transfer processes in Ca2MgWO6:Cr3+,Yb3+ phosphor are proposed with simplified energy level diagrams. The Cr3+/Yb3+ co-doped Ca2MgWO6 phosphor converts ultraviolet (240–400 nm) photons into NIR (900–1050 nm) ones, which matches well with the optimal spectral response of silicon (Si) solar cells, and is expected to be promising as a luminescent solar concentrator for photovoltaic solar cells.