Abnormal Anti‐Quenching and Controllable Multi‐Transitions of Bi3+ Luminescence by Temperature in a Yellow‐Emitting LuVO4:Bi3+ Phosphor for UV‐Converted White LEDs |
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| Authors: | Fengwen Kang Prof. Dr. Mingying Peng Prof. Dr. Qinyuan Zhang Prof. Dr. Jianrong Qiu |
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| Affiliation: | The China‐Germany Research Center for Photonic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices and the Institute of Optical Communication Materials, School of Materials Science and Engineering, South China University of Technology, Guangzhou 510641 (P.R. China), Fax: (+86)?20‐22236910 |
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| Abstract: | Phosphors with an efficient yellow‐emitting color play a crucial role in phosphor‐converted white LEDs (pc‐WLEDs), but popular yellow phosphors such as YAG:Ce or Eu2+‐doped (oxy)nitrides cannot smoothly meet this seemingly simple requirement due to their strong absorptions in the visible range. Herein, we report a novel yellow‐emitting LuVO4:Bi3+ phosphor that can solve this shortcoming. The emission from LuVO4:Bi3+ shows a peak at 576 nm with a quantum efficiency (QE) of up to 68 %, good resistance to thermal quenching (T50 %=573 K), and no severe thermal degradation after heating–cooling cycles upon UV excitation. The yellow emission, as verified by X‐ray photoelectron spectra (XPS), originates from the (3P0,3P1)→1S0 transitions of Bi3+. Increasing the temperature from 10 to 300 K produces a temperature‐dependent energy‐transfer process between VO43? groups and Bi3+, and further heating of the samples to 573 K intensifies the emission. However, it subsequently weakens, accompanied by blueshifts of the emission peaks. This abnormal anti‐thermal quenching can be ascribed to temperature‐dependent energy transfer from VO43? groups to Bi3+, a population redistribution between the excited states of 3P0 and 3P1 upon thermal stimulation, and discharge of electrons trapped in defects with a trap depth of 359 K. Device fabrication with the as‐prepared phosphor LuVO4:Bi3+ has proved that it can act as a good yellow phosphor for pc‐WLEDs. |
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| Keywords: | bismuth energy transfer light‐emitting diodes lutetium vanadate phosphors quantum yield thermal stimulation |
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