title: Abnormal anti-quenching and controllable multi-transitions of Bi3+ luminescence by temperature in a yellow-emitting LuVO4 :Bi3+ phosphor for UV-converted white LEDs.
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 Eu(2+) -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 LuVO(4) :Bi(3+) phosphor that can solve this shortcoming. The emission from LuVO(4) :Bi(3+) shows a peak at 576 nm with a quantum efficiency (QE) of up to 68 %, good resistance to thermal quenching (T(50 %) =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 ((3)P(0),(3)P(1))→(1) S0 transitions of Bi(3+). Increasing the temperature from 10 to 300 K produces a temperature-dependent energy-transfer process between VO(4)(3-) groups and Bi(3+), 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 VO(4)(3-) groups to Bi(3+), a population redistribution between the excited states of (3)P(0) and (3)P(1) upon thermal stimulation, and discharge of electrons trapped in defects with a trap depth of 359 K. Device fabrication with the as-prepared phosphor LuVO(4) :Bi(3+) has proved that it can act as a good yellow phosphor for pc-WLEDs.
authors.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.
authors.forename: Fengwen
authors.initials: F
authors.lastname: Kang
authors.forename: Mingying
authors.initials: M
authors.lastname: Peng
authors.forename: Qinyuan
authors.initials: Q
authors.lastname: Zhang
authors.forename: Jianrong
authors.initials: J
authors.lastname: Qiu
keywords: bismuth; energy transfer; light-emitting diodes; lutetium vanadate; phosphors; quantum yield; thermal stimulation