Broadband Yellow-Emitting Oxynitride Phosphor Sr2Si7Al3ON13:Ce3+,Eu2+ for White Light-Emitting Diodes with a High Color Rendering Index.

Abstract

The utilization of blue LED chips in conjunction with the commercial yellow phosphor YAG:Ce3+ currently represents the most straightforward and efficient approach for generating white light, albeit at a slight compromise to the color rendering index. However, by expansion of the spectral coverage of the yellow phosphor, it becomes feasible to achieve a high color rendering index for white light. In this study, we synthesized a broadband yellow oxynitride phosphor through codoping Ce3+ and Eu2+ on highly chemically stable Sr2Si7Al3ON13. We conducted an extensive investigation of the energy transfer process between Ce3+ and Eu2+ within Sr2Si7Al3ON13:Ce3+,Eu2+. By adjusting the doping concentration of Eu2+, we successfully obtained a higher emission intensity and improved thermal stability for Sr2Si7Al3ON13:Ce3+,Eu2+ under 450 nm blue-light excitation. Furthermore, we achieved a full width at half-maximum (fwhm) broadened to 130 nm along with an optimal external quantum efficiency (EQE) of 43.2%. The resulting WLED devices utilizing this yellow phosphor exhibited high color rendering index (CRI, Ra = 86.2) white light emission (0.3488, 0.3407). These exceptional properties highlight the significant potential application of Sr2Si7Al3ON13:Ce3+,Eu2+ in blue light-excited WLED as well as its promising prospects in indoor display lighting.