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Concentration-Driven Selectivity of Energy Transfer Channels and Color Tunability in Ba3La(PO4)3:Tb3+, Sm3+ for Warm White LEDs
journal contribution
posted on 2017-06-16, 18:22 authored by Weijie Zhou, Meng Gu, Yiyi Ou, Caihua Zhang, Xuejie Zhang, Lei Zhou, Hongbin LiangHere, we report the large-scale emission
color tunability in Ba3La(PO4)3:Tb3+, Sm3+ (BLPO:TS) system based on the detailed
discussion on the concentration-driven
selectivity of energy transfer (ET) channels from Tb3+ to
Sm3+. It is induced by the concentration-dependent 5D3 and 5D4 emissions of Tb3+ and the different interaction mechanisms of ET from Tb3+ to Sm3+ via 5D3 and 5D4 channels. In the diluted Tb3+ scenario,
the red emission of Sm3+ is efficiently sensitized via
the 5D3 channel, while in the concentrated Tb3+ case, the contribution of 5D4 channel
is dominant. Therefore, by simply adjusting the doping concentrations
of Tb3+ and Sm3+, the emission color of the
phosphors can be tuned from green to red. In view of the phosphors
with red emissions are critical to the warm white light-emitting diodes
(WLEDs), an orange-red Tb3+, Sm3+ coactivated
phosphor Ba3La0.90Tb0.05Sm0.05(PO4)3 (BLPO:5T5S) with good thermal and chromaticity
stability and internal quantum efficiency ∼67% is developed
in the system. Then, a near-UV WLED (CCT ≈ 4500 K, Ra ≈ 81) is fabricated using this phosphor.
These findings not only indicate that the orange-red phosphor BLPO:5T5S
is available for near-UV warm white LEDs but also deliver new insights
into the ET processes in Tb3+ and Sm3+ activated
phosphors.
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CCTemission colorchromaticity stabilityinteraction mechanismsnear-UV WLEDconcentration-dependent 5 D 3ET processes5 D 35 D 4 channel5 D 4 emissionsconcentration-driven selectivity5 D 3 channel5 D 4 channelslight-emitting diodesPO 4Warm White LEDsEnergy Transfer ChannelsConcentration-Driven Selectivityemission color tunabilitySmphosphorTbBLPOColor Tunabilitydoping concentrationsenergy transfer
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