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07:03
Low-energy Cathodoluminescence for OxyNitride Phosphors
Published on: November 15, 2016
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UV/VUV switch-driven color-reversal effect for Tb-activated phosphors
Chun Che Lin1, Wei-Ting Chen1, Cheng-I Chu1
1Department of Chemistry, Taiwan University, Taipei.
Light, Science & Applications
|September 1, 2018
Summary
Researchers discovered that changing excitation from UV to vacuum UV (VUV) light switches terbium-doped phosphors from green to blue emission. This color reversal is explained by a configurational coordinate model.
Area of Science:
- Materials Science
- Solid-State Physics
- Luminescence
Background:
- Trivalent lanthanide-doped phosphors are crucial for displays and lamps.
- Their emission properties are sensitive to excitation wavelength and dopant concentration.
- Mechanisms behind emission color shifts in Tb³⁺-doped phosphors are not fully understood.
Purpose of the Study:
- To investigate the UV/VUV switchable photoluminescence of Ba₃Si₆O₁₂N₂:Tb.
- To elucidate the underlying mechanisms for the observed green-to-blue emission color reversal.
- To propose a model explaining the color-switching phenomenon.
Main Methods:
- Excitation of Ba₃Si₆O₁₂N₂:Tb phosphor with UV and vacuum UV (VUV) radiation.
- Systematic control of excitation wavelength to observe photoluminescence changes.
- Application of a configurational coordinate model to explain the observed color reversal.
Main Results:
- UV excitation resulted in green photoluminescence.
- VUV excitation led to a blue photoluminescence.
- A configurational coordinate model successfully explained the transition between green (⁵D₄ state) and blue (⁵D₃ state) emission.
Conclusions:
- A UV/VUV switch enables tunable emission color in Tb³⁺-doped phosphors.
- The color reversal is attributed to excitation-dependent population of different excited states (⁵D₄ vs. ⁵D₃).
- The proposed model offers a generalizable mechanism for controlling optical properties in Tb-doped phosphors.
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