Upconversion in NaYF(4):Yb, Er nanoparticles amplified by metal nanostructures

Area of Science:

• Materials Science
• Nanotechnology
• Photonics

Background:

• Upconversion (UC) fluorescence is crucial for various photonic applications.
• Metal nanostructures can enhance UC luminescence through plasmonic effects.
• Understanding the influence of nanostructure geometry on UC enhancement is vital.

Purpose of the Study:

• To compare the UC fluorescence enhancement of NaYF(4):Yb, Er nanoparticles using two distinct metal nanostructure geometries.
• To investigate the impact of gold nanoshells and silver nanostructures on UC emission intensity and lifetime.
• To elucidate the underlying mechanisms responsible for the observed plasmonic enhancement.

Main Methods:

• Fabrication of NaYF(4):Yb, Er nanoparticles.
• Integration of nanoparticles with gold nanoshells and adjacent silver nanostructures on a silica surface.
• Characterization of UC fluorescence intensity and lifetime under varying conditions.

Main Results:

• Silver nanostructures enhanced green and red UC emissions by approximately 4.4-fold and 3.5-fold, respectively, while reducing UC lifetimes.
• Gold nanoshells yielded higher enhancement factors (∼9.1-fold for green, ∼6.7-fold for red) but showed varied lifetime effects.
• Gold shell coating extended red emission lifetime by 1.5-fold, with minimal impact on green emission lifetime.

Conclusions:

• Both gold nanoshells and silver nanostructures effectively enhance UC fluorescence from NaYF(4):Yb, Er nanoparticles.
• The geometry of the metal nanostructure significantly influences the degree of UC enhancement and lifetime modification.
• Plasmonic enhancement and surface effects are key mechanisms governing the observed phenomena.