Related Experiment Video
Updated: Jun 17, 2025
07:03
Low-energy Cathodoluminescence for OxyNitride Phosphors
Published on: November 15, 2016
10.6K
Spinel-Type Structured Phosphor Near-Infrared-II Emission: Intervalence Charge Transfer and Hetero-Valent Chromium
Ming-Hsuan Huang1, Kuan-Chun Chen1, Natalia Majewska2
1Department of Chemistry, National Taiwan University, 106, Taipei, Taiwan.
Angewandte Chemie (International Ed. in English)
|August 8, 2024
Summary
Researchers developed novel near-infrared (NIR) emitting phosphors using lithium gallium oxide (LiGa5O8) with chromium (Cr3+) activators. A key finding is the intervalence charge transfer (IVCT) mechanism responsible for NIR-II emission, offering new design strategies.
Area of Science:
- Materials Science
- Solid-State Chemistry
- Luminescence
Background:
- Near-infrared (NIR) emitting phosphors are crucial for various applications.
- Developing phosphors with tunable emission in NIR-I and NIR-II regions is an active research area.
Purpose of the Study:
- To synthesize and characterize LiGa5O8 phosphors doped with high concentrations of Cr3+ activators.
- To investigate the emission mechanisms, particularly for NIR-II emission, in these phosphors.
Main Methods:
- Synthesis of inverse spinel-type LiGa5O8 phosphors.
- Structural characterization using X-ray diffraction and luminescence spectroscopy.
- Analysis of emission mechanisms, including intervalence charge transfer (IVCT).
Main Results:
- A series of LiGa5O8:Cr3+ phosphors exhibiting dual emission bands in the NIR-I and NIR-II regions were successfully synthesized.
- An intervalence charge transfer (IVCT) process between aggregated Cr3+ ions was identified as the primary mechanism for the ~1210 nm NIR-II emission.
- Structural distortions and irradiation were found to enhance the IVCT process.
Conclusions:
- The study elucidates the emission mechanism in high Cr3+ concentration LiGa5O8 phosphors.
- A novel design strategy for NIR-II emitting phosphors based on IVCT is proposed.
- This research contributes to the development of advanced NIR-II phosphors with enhanced response.
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