Great emission enhancement of high-efficient broadband K3YSi2O7: Eu red phosphor via enhancing crystallinity

Abstract

Doping with alkali metal ions is an effective and universal method for luminescent efficiency enhancement of phosphors, but the corresponding mechanism of improvement remains ambiguous. This study presents a systematic investigation toward K+ excess-doped K3YSi2O7: Eu orange-emitting phosphor, whose emission intensity could reach to 200% enhancement over stoichiometric K+ sample. Analysis of X-ray diffraction, steady-state and dynamic fluorescence spectroscopies indicate that luminescent enhancement led by optimized K+ doping was mainly attributed to crystallinity enhancement. The optimized-composition phosphor, K3YSi2O7: Eu (140% K), shows improved emission thermal stability (60% of RT value at 200 °C) as well as enhanced internal quantum efficiency of 74.58% compared with 34.58% of stoichiometric K+ sample. As-fabricated white LED prototype exhibits excellent color quality (Ra = 92.2) along with low color temperature (CCT = 3089 K). The results indicate that the promising properties of the K3YSi2O7: Eu (140% K) red phosphor can ensure the better luminous performance of white LEDs.