A Highly Efficient Phosphor Sr2sio4:Ce3+/K+ with Thermally Enhanced Blue Emission

Abstract

Blue-emitting phosphor is one of the trichromatic phosphors essential for the development of near-ultraviolet (nUV) pumped phosphor-converted white light-emitting diodes (pc-WLEDs). Efficiency and thermal stability are two critical factors for the potential application of phosphors in solid-state lighting. In this work, we report a highly efficient blue-emitting phosphor α-Sr2SiO4:0.02Ce3+/0.02K+ which exhibits superior thermally enhanced photoluminescence properties. Its emission intensity was boosted gradually while raising the temperature. Specifically, it retains 120% of its room-temperature peak intensity at 250 °C. It has no color drift problem, as the emission peak does not shift at elevated temperatures. Under the nUV irradiation, the phosphor is highly luminous with an excellent internal quantum efficiency (IQE) of 91.7%, with the emission peak at 425 nm. The abnormal thermal quenching phenomenon can be ascribed to the defect energy levels introduced by the defect engineering using an aliovalent doping strategy of Ce3+ and K+ in the α-Sr2SiO4 host structure. The as-fabricated WLED prototypes demonstrated the great potential of the highly efficient blue-emitting phosphor with superior thermal stability for solid-state lighting applications.

Keywords: strontium orthosilicate (Sr2SiO4), abnormal thermal quenching, quantum efficiency, photoluminescence, defect engineering