Antithermal Quenching Upconversion Luminescence via Suppressed Multiphonon Relaxation in Positive/Negative Thermal...

Area of Science:

• Materials Science
• Luminescence
• Nanotechnology

Background:

• Thermal quenching (TQ) is a major limitation in luminescence, often caused by multiphonon relaxation (MPR).
• MPR is linked to lattice vibrations and can be influenced by external pressure.

Purpose of the Study:

• To design a core/shell upconversion luminescence (UCL) system that suppresses MPR and reduces TQ.
• To achieve anti-TQ or thermally enhanced UCL by imposing pressure on the core lattice.

Main Methods:

• Fabrication of a core/shell structure: α-NaYF₄:Yb/Ln@ScF₃ (Ln = Ho, Er, Tm).
• Utilizing materials with opposing thermal expansion (positive core, negative shell).
• Investigating the effect of shell-induced pressure on core lattice and luminescence properties.

Main Results:

• The negative thermal expansion of the ScF₃ shell restrained the positive thermal expansion of the α-NaYF₄ core upon heating.
• This restraint imposed pressure on the core lattice, suppressing MPR and reducing TQ.
• Observed anti-TQ or thermally enhanced UCL, indicating improved luminescence efficiency.

Conclusions:

• A novel core/shell UCL system effectively suppresses thermal quenching through shell-induced pressure.
• This strategy offers a new pathway for developing highly efficient luminescent materials for various applications.