Novel green-emitting K2Ba5Si12O30:Eu2+ phosphors with excellent thermal quenching for white light-emitting diodes

Abstract

A novel green-emitting phosphor – K2Ba5Si12O30:Eu2+ (KBSO:Eu2+) was successfully synthesized via a solid state reaction. The crystal structure, luminescent properties as well as thermal quenching and LED fabrication were systematically carried out in this study. The emission and excitation spectra indicate that KBSO:Eu2+ phosphors exhibit broad excitation spectra ranging from 260 to 480 nm and an intense broad green emission at 497 nm under 370 nm excitation. The chromaticity coordinates of composition-optimized KBSO:Eu2+ phosphor is situated in the green region with coordinates (0.2404, 0.4429). The temperature-dependent photoluminescence demonstrates that KBSO:Eu2+ gives a good thermal quenching performance of ∼80% at 100 °C, which is much superior to that of commercial silicate-based phosphor of (Ba, Sr)2SiO4:Eu2+. Warm-white light-emitting diodes (LEDs) fabricated using an NUV-chip combined with the KBSO:3%Eu2+ phosphor gave color rendering indices 82.65, correlated color temperatures 4939 K, and the CIE chromaticity coordinates 0.3064, 0.3325). These results indicate that KBSO:Eu2+ is a potential green-emission phosphor for near UV and high powder white-light LEDs.