Photon avalanche assisted upconversion via customizing the green emission

Area of Science:

• Materials Science
• Luminescence
• Solid-State Chemistry

Background:

• Upconversion (UC) materials are crucial for advanced optical applications.
• Tin tungstate (SnWO4) is a promising host material for luminescent ions.
• Understanding doping effects is key to tuning phosphor properties.

Purpose of the Study:

• To synthesize and characterize SnWO4 phosphors doped with Ho3+, Yb3+, and Mn4+ ions.
• To optimize dopant concentrations for enhanced upconversion luminescence.
• To investigate the mechanisms behind luminescence enhancement and spectral shifts.

Main Methods:

• Synthesis of SnWO4 phosphors with varying concentrations of Ho3+, Yb3+, and Mn4+.
• Characterization using spectroscopic techniques under 980 nm laser excitation.
• Analysis of energy transfer, charge compensation, and concentration quenching mechanisms.

Main Results:

• Optimized dopant concentrations (0.5 Ho3+, 3.0 Yb3+, 5.0 Mn4+) significantly amplified upconversion emission (up to 13 times).
• Incorporation of Mn4+ ions induced a shift from green to reddish broadband emission via a photon avalanche mechanism.
• Concentration quenching mechanisms were identified as dipole-quadrupole and exchange interactions for different doping combinations.

Conclusions:

• The developed Ho3+/Yb3+/Mn4+ codoped SnWO4 phosphors exhibit significantly enhanced upconversion properties.
• The study elucidates the energy transfer dynamics and spectral modification mechanisms in these novel phosphors.
• Determined activation energy (0.19 eV) and discussed thermal quenching, providing insights for practical applications.