Near-infrared downconversion luminescence of SrMoO₄:Tm³⁺,Yb³⁺ phosphors

Graphical abstract: The calculated band structure of SrMoO₄ and the visible and infrared emission spectra of SrMoO₄:1%Tm³⁺,10%Yb³⁺ phosphors under 283 nm excitation.▪ - Highlights: • Near-infrared downconversion luminescence of SrMoO₄:Tm³⁺,Yb³⁺ phosphors were systematically investigated. • The electronic structure of SrMoO₄ was estimated by density functional theory. • The quenching concentration of Yb³⁺ ions approaches 10 mol%. • The energy transfer mechanism was discussed in detail. - Abstract: Tm³⁺ and Yb³⁺ codoped SrMoO₄ phosphors were synthesized by the high-temperature solid-state reaction method. The structure, ultraviolet-visible diffuse reflectance spectra, photoluminescence, decay properties and theoretical energy transfer efficiency of the phosphors were investigated in detail. The electronic structure and band gap of SrMoO₄ were estimated by density functional theory (DFT) calculation. The XRD results show that all the prepared phosphors can be readily indexed to scheelite-type structure. The strong visible emission around 473 nm from Tm³⁺ (¹G₄ → ³H₆) and near-infrared (NIR) emission around 998 nm from Yb³⁺ (²F_5/2 → ²F_7/2) of the SrMoO₄:Tm³⁺,Yb³⁺ phosphors were observed under 283 nm excitation. The dependence of the visible and NIR emissions on Yb³⁺ concentration have also been investigated. The quenching concentration of Yb³⁺ ions approaches 10 mol%. In addition, the energy transfer processes and possible transfer routes were proposed.