Plasmon-enhanced upconversion in single NaYF4:Yb3+/Er3+ codoped nanocrystals.

Area of Science:

• Materials Science
• Nanotechnology
• Photonics

Background:

• Upconversion luminescence in lanthanide-doped nanocrystals is crucial for various optical applications.
• Controlling and enhancing upconversion efficiency in single nanoparticles remains a significant challenge.

Purpose of the Study:

• To investigate plasmon-enhanced upconversion in single sodium yttrium fluoride (NaYF4) nanocrystals codoped with Yb3+/Er3+.
• To explore the effect of coupling single nanocrystals with gold nanospheres on upconversion emission.

Main Methods:

• Utilized a combined confocal and atomic force microscope setup for precise manipulation and investigation.
• Assembled single NaYF4 nanocrystals with gold nanospheres (30 and 60 nm in diameter).
• Performed time-resolved measurements to analyze excitation and emission dynamics.

Main Results:

• Observed strong green and red upconversion emission from single NaYF4:Yb3+/Er3+ nanocrystals under 973 nm near-infrared excitation.
• Achieved an overall enhancement factor of 3.8 by coupling nanocrystals with gold nanospheres.
• Time-resolved studies revealed faster excitation and emission in coupled nanocrystal-gold sphere systems.

Conclusions:

• Plasmonic coupling with gold nanospheres effectively enhances upconversion luminescence in single NaYF4 nanocrystals.
• The observed enhancement is attributed to modified excitation and emission rates.
• This work demonstrates a viable strategy for boosting the performance of single upconverting nanoparticles for advanced applications.