Ultra-bright green-emitting phosphors with an internal quantum efficiency of over 90% for high-quality WLEDs

There is an urgent need to develop phosphors with high quantum efficiencies (QEs) since white light-emitting diodes (WLEDs) have emerged as a new generation of illumination materials. Utilizing energy transfer to improve the absorption of activators and adjust the emission colors of samples is one e...

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Published in:Dalton transactions : an international journal of inorganic chemistry 2021-03, Vol.5 (12), p.4159-4166
Main Authors: Li, Yanyan, Yin, Yuan, Wang, Tianli, Wu, Junxiao, Zhang, Jia, Yu, Shuaishuai, Zhang, Meiguang, Zhao, Lei, Wang, Wenjie
Format: Article
Language:English
Subjects:
Cerium
Color temperature
Energy transfer
Europium
Light emitting diodes
Phosphors
Quantum efficiency
Terbium
Thermal stability
White light
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Summary:There is an urgent need to develop phosphors with high quantum efficiencies (QEs) since white light-emitting diodes (WLEDs) have emerged as a new generation of illumination materials. Utilizing energy transfer to improve the absorption of activators and adjust the emission colors of samples is one effective strategy. Here, color-tunable phosphors of the form CaAl 4 O 7 :Ce,Tb were synthesized aiming at efficient energy transfer from Ce 3+ to Tb 3+ . Since Tb 3+ can be suitably sensitized by Ce 3+ , the co-doped phosphors can be effectively excited by near-ultraviolet (NUV) light. The internal QE of CaAl 4 O 7 :0.04Ce,0.04Tb under 350 nm excitation is as high as 92.55%, and the external QE is 71.02%. A WLED fabricated from BAM:Eu 2+ , CaAl 4 O 7 :0.04Ce,0.04Tb, and CaAlSiN 3 :Eu 2+ with a 365 nm LED chip exhibited a correlated color temperature (CCT) of 4706 K and a color rendering index (CRI, R a ) of 81.44. The energy transfer mechanism and thermal stability of the phosphor were also investigated. The results provide an effective approach for developing highly efficient green-emitting phosphors for NUV WLEDs. Ultra-bright color-tunable phosphors of the form CaAl 4 O 7 :0.04Ce, z Tb with high quantum efficiency were synthesized.
ISSN:1477-9226
1477-9234
DOI:10.1039/d1dt00345c