A novel red-emitting K₂Ca(PO₄)F:Eu²⁺ phosphor with a large Stokes shift

Area of Science:

• Materials Science
• Solid-State Chemistry
• Luminescence

Background:

• Phosphor materials are crucial for light conversion applications, including lighting and displays.
• Developing novel phosphors with desirable optical properties, such as efficient luminescence and specific emission wavelengths, is an ongoing research area.
• Understanding the relationship between crystal structure and luminescence properties is key to designing advanced phosphors.

Purpose of the Study:

• To synthesize and characterize a new K2CaPO4F:Eu2+ phosphor.
• To investigate the luminescence properties, including Stokes shift and spectral conversion capabilities.
• To elucidate the underlying mechanism of luminescence using theoretical calculations.

Main Methods:

• Synthesis of K2CaPO4F:Eu2+ phosphor.
• Structural characterization using X-ray diffraction.
• Optical measurements to determine luminescence spectra and Stokes shift.
• Computational analysis using constrained density functional theory (DFT).

Main Results:

• A novel K2CaPO4F:Eu2+ phosphor with a unique crystal structure was successfully synthesized.
• The phosphor exhibits efficient red luminescence upon excitation with near-ultraviolet light.
• A large Stokes shift was observed, indicating minimal reabsorption of emitted light.
• Constrained DFT calculations provided insights into the luminescence mechanism.

Conclusions:

• The K2CaPO4F:Eu2+ phosphor is a promising material for near-UV to red light conversion.
• Its large Stokes shift and efficient luminescence are attributed to its novel crystal structure.
• Theoretical investigations successfully explained the observed luminescent properties.