Efficient white light emission from a single silicate host with promising color quality for white light emitting diodes

Strontium silicate phosphors were synthesized via a solid-state route with different silicon sources as SiO2 and Si3N4. The phosphors synthesized with Si3N4 exhibited improved luminescence properties for white emission because of the coexistence of Sr3MgSi2O8 and Sr2SiO4 phases. Under UV excitation, white light was observed due to the combination of blue emission from Sr3MgSi2O8: Eu2+ and yellow emission from Sr2SiO4: Eu2+. The broad Eu2+ emission was explained on the basis of the dependency of crystal field strength on the site selection. The variation of Eu2+ ion concentration controlled the quality of the emitted light and at 5 mol% Eu2+, near white emission (0.30, 0.31) was obtained with external and internal quantum efficiencies of 50% and 68%, respectively. The WLEDs were fabricated by coating the present phosphors on an InGaN UV- LED chips and the EL spectrum displayed near white chromaticity (0.31, 0.33) with color rendering index of 80 and CCT of 6850 K. The results demonstrated the promising single host phosphors for near-UV white-light-emitting diodes.