Luminescence properties of Li2SrSiO4:Eu2+ silicate yellow phosphors with high thermal stability for high-power efficiency white LED application

Highlights: • Synthesized by polymerized complex method. • Emission intensity by polymerized complex method is 6 times higher than solid state reaction. • 80% emission intensity at high temperature compared with room temperature. • Higher thermal stability than YAG:Ce³⁺. • Explanation of emission processes by configuration coordinate models. -- Abstract: Li₂SrSiO₄:Eu²⁺ yellow phosphors were synthesized by Polymerized Complex Method using TEOS and their thermal stability was investigated. The synthesized phosphors exhibited a broad yellow emission band around 560 nm. The optimum H₂/N₂ reduction temperature and Eu concentration are 900 °C and 0.5% respectively, which show the highest PL intensity and 6 times higher than samples synthesized by conventional solid-state reaction at the same condition. In order to investigate the thermal stability, PL properties in temperature range from 16.4 K to 583 K were examined. The PL intensity remains 80% above at high temperature (438 K) compared with room temperature. Activation energy and internal quantum efficiency of samples are estimated to be 0.43 eV and 62% respectively. Emission processes in Li₂SrSiO₄:Eu²⁺ phosphor were discussed with configuration coordinate model. The results reveal that Li₂SrSiO₄:Eu²⁺ yellow phosphors shows excellent thermal stability and have feasibility in replacement of YAG:Ce³⁺ yellow phosphors in white LEDs application.