Be2+‐Induced Red Emission Enhancement in CaAl12O19:Mn4+ for Wide Color Gamut Display: Suppressing Self‐Reduction of Mn4+ to Mn2

• Published in: Advanced optical materials Vol. 12; no. 3
• Main Authors: Zheng, Liwen, Zhang, Liangliang, Fang, Limin, Wu, Hao, Wu, Huajun, Pan, Guo‐Hui, Yang, Yuxin, Luo, Yongshi, Hao, Zhendong, Zhang, Jiahua
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.01.2024
• Subjects: Backlights; charge compensation; Color; Compensation; Doping; Efficiency; Light emitting diodes; Luminescence; Mn4; oxide; Phosphors; Photoluminescence; Quantum efficiency; red phosphor; self‐reduction
• ISSN: 2195-1071; 2195-1071
• DOI: 10.1002/adom.202301480

Mn4+‐activated CaAl12O19 (CAO: Mn4+) is recognized as a promising candidate for red phosphor used in wide color gamut displays. However, the spontaneous self‐reduction of Mn4+ to Mn2+ occurs for charge compensation through Mn2+‐Mn4+ substitution for Al3+‐Al3+, lowering the quantum efficiency of Mn4+. To suppress the self‐reduction, some divalent metal ions, including Ba2+, Sr2+, Cd2+, Zn2+, and Mg2+, are added for charge compensation instead of Mn2+, but only small luminescence enhancement is observed. In this paper, remarkable luminescence enhancement in CAO: Mn4+ via co‐doping Be2+ is reported. The photoluminescence properties are studied as a function of Be2+ doping concentration, and the optimal Be2+ concentration of 0.01 is found. The internal quantum efficiency of 74.9% and external quantum efficiency of 56.3% are achieved under UV excitation, higher than those via co‐doping other divalent metal ions. This study indicates that the addition of Be2+ dominates the charge compensation because Be2+ is closer to Al3+ in size than Mn2+ and other divalent metal ions. The backlight light‐emitting diodes using CAO: Mn4+, Be2+ are fabricated, exhibiting a 110.1% Nation Television Standards Committee (NTSC) color gamut, wider than both the current commercial backlight using K2SiF6: Mn4+ (KSF) red phosphor and the conventional one using YAG yellow phosphor. Remarkable luminescence enhancement is realized in CaAl12O19: Mn4+ (CAO: Mn4+) via co‐doping Be2+because Be2+ is closer to Al3+ in size than Mn2+. The internal quantum efficiency of 74.9% and external quantum efficiency of 56.3% are achieved under UV excitation. The backlight light‐emitting diodes using CAO: Mn4+, Be2+ exhibit a 110.1% NTSC (Nation Television Standards Committee) color gamut.