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, R_a = 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.