Tunable broadband luminescence of the novel Sn2+ doped oxyfluoride glass and glass-ceramics for W-LEDs

Abstract

The demand for white-light luminescent materials for the white-light-emitting diodes (W-LEDs) field has been growing in modern life. In this work, a series of Sn²⁺ and Mn²⁺ ions co-doped highly transparent white-light emitting oxyfluoride glasses (precursor glass, PG) and Sr₂LuF₇ glass-ceramics (GC) were successfully prepared by the melt-quenching technique. Their luminescent and structural properties were investigated by the transmission spectra, excitation and emission spectra at different temperatures (300-500 K), luminescent decay curves, XRD, and TEM characterizations. Upon excitation with ultraviolet (UV) light, tunable broadband blue-white light emissions of Sn²⁺ were obtained by adjusting the concentration of Sn²⁺ ions. A conspicuous energy transfer process from Sn²⁺ to Mn²⁺ was observed in Sn²⁺/Mn²⁺ co-doped samples. Tunable broadband luminescence between blue-white light and orange-red light regions and nearly pink-white light emission was realized by varying Mn²⁺ concentration. Furthermore, compared to PG samples, the emissions were enhanced in GC samples due to the crystallization of Sr₂LuF₇ nanocrystals. Excellent thermal stability was also performed in these Sn²⁺ doped PG and GC samples with a recovering value of 96 % and 98.8 %, respectively. Simultaneously, Sn²⁺ doped PG and GC samples also own good optical thermal sensitivities with an S_A value of 2.28 % and 2.47 % K^-1, respectively. Our results indicate that these Sn²⁺/Mn²⁺ co-doped PG and GC may serve as tunable light sources under UV excitation and have prospects on the ratiometric optical thermometry fields.