Lanthanide-Doped KMgF₃ Upconversion Nanoparticles for Photon Avalanche Luminescence with Giant Nonlinearities

Area of Science:

• Materials Science
• Nanotechnology
• Photonics

Background:

• Lanthanide (Ln³⁺)-doped upconversion nanoparticles (UCNPs) show promise for advanced technologies.
• Efficient photon avalanche (PA) luminescence in UCNPs is hindered by surface and lattice quenching effects.

Purpose of the Study:

• To develop a controlled synthesis method for aliovalent Ln³⁺-doped KMgF₃ UCNPs.
• To mitigate luminescence quenching in UCNPs and enhance PA efficiency.

Main Methods:

• Utilized pyrolysis of KHF₂ for controlled synthesis of KMgF₃ UCNPs.
• Incorporated aliovalent Ln³⁺ doping to protect against OH^- defects.

Main Results:

• Achieved efficient PA luminescence from Tm³⁺ at 802 nm in KMgF₃: Tm³⁺ UCNPs.
• Demonstrated a high nonlinearity (∼27), a PA response time of 281 ms, and a low excitation threshold (16.6 kW cm^-2).

Conclusions:

• The KHF₂ pyrolysis method effectively suppresses luminescence quenching in UCNPs.
• Aliovalent Ln³⁺ doping and crystal lattice engineering offer a new route for highly nonlinear PA luminescence.