Efficient and Tunable Near-Infrared Luminescence in Cubic Phosphate K₂AlTi(PO₄)₃:Cr³⁺ for Spectroscopy Applications

Area of Science:

• Materials Science
• Solid-State Chemistry
• Optoelectronics

Background:

• Broadband near-infrared (NIR) phosphors are essential for NIR phosphor-converted light-emitting diode (pc-LED) technologies used in smart spectroscopy.
• Developing efficient, tunable, and affordable NIR phosphors with broad spectral coverage presents a significant challenge.

Purpose of the Study:

• To synthesize and characterize a novel broadband NIR phosphor based on a cubic phosphate host material (K2AlTi(PO4)3) doped with Cr3+.
• To evaluate the photoluminescence properties and potential applications of the synthesized material in NIR pc-LEDs.

Main Methods:

• Synthesis of K2AlTi(PO4)3:Cr3+ phosphor.
• Characterization of structural and optical properties, including photoluminescence spectra, quantum yield, and luminescence dynamics.
• Fabrication and testing of NIR pc-LED devices.
• First-principle calculations to understand the emission mechanism.

Main Results:

• The synthesized K2AlTi(PO4)3:Cr3+ exhibits broadband NIR emission from 700-1200 nm, tunable with Cr3+ concentration.
• Optimized samples show a photoluminescence quantum yield (PLQY) of 76.4% with emission peaking at 857 nm and a wide full width at half-maximum (fwhm) of 184 nm.
• The NIR pc-LED device demonstrated excellent NIR output power and photoelectric conversion efficiency.

Conclusions:

• The K2AlTi(PO4)3:Cr3+ phosphor is a promising, low-cost, highly efficient material for broadband NIR emission with wide spectral coverage.
• The material's tunable and efficient NIR output makes it attractive for applications in night-vision, bioimaging, and spectroscopy.
• This study provides insights into discovering similar NIR-emitting materials.