Temperature-Dependent Luminescence Characteristic of SrSi2O2N2:Eu2+ Phosphor and Its Thermal Quenching Behavior

The yellow SrSi2O2N2:Eu2+ phosphor has been synthesized by using a simple solid-state reaction method with Sr2SiO4:Eu2+ as the precursor. It shows a broad excitation band extending from 250 to 520 nm and an asymmetric emission band with a main peak at about 550 nm. The emission intensity of the SrSi2O2N2:Eu2+ is about 1.2 times higher than the commercial yellow phosphor YAG:Ce3+ (P46-Y3). The temperature-dependent luminescence characteristic of SrSi2O2N2:Eu2+ has been investigated in this paper. With increasing temperature, the emission band of SrSi2O2N2:Eu2+ shows anomalous blue-shift along with decreasing emission intensity and the broadening full width at half maximum (FWHM). Particularly, compared with YAG:Ce3+ (P46-Y3), the yellow SrSi2O2N2:Eu2+ phosphors exhibit higher thermal stability due to their weaker electron-phonon coupling strength (1.1), lower stokes shift (0.0576 eV) and larger activation energy (0.288 eV). All these results indicate that SrSi2O2N2:Eu2+ yellow phosphors have potential application for white light-emitting diodes (LEDs). What's more, an energy level scheme is constructed to explain the anomalous blue-shift phenomenon.