Asymmetric Nanocrescent Antenna on Upconversion Nanocrystal

Area of Science:

• Nanophotonics
• Materials Science
• Luminescence

Background:

• Lanthanide-based frequency upconversion offers advantages over traditional nonlinear methods but suffers from low quantum yield and poor spatial control.
• Existing upconversion nanocrystals are inefficient for practical applications, limiting their widespread use.

Purpose of the Study:

• To develop a novel nanostructure for enhanced frequency upconversion with spatial emission control.
• To improve the efficiency and directional output of lanthanide-based upconversion nanocrystals.

Main Methods:

• Fabrication of asymmetric nanocrescent antennae on upconversion nanocrystals (ANAUs) using high-angle gold deposition on nanopillar-supported nanoparticles.
• Analysis of orientation-dependent upconversion luminescence on a single-nanoparticle scale.
• Shape-dependent nanofocusing efficiency studies by modulating deposition angles.
• Simulation of asymmetric emission patterns using dipole radiation models.

Main Results:

• Demonstrated effective excitation light delivery to upconversion nanocrystal cores via nanofocusing.
• Achieved asymmetric frequency upconverted emission concentrated towards the tip region of the ANAU.
• Experimentally verified orientation-dependent photon intensity correlating with simulated asymmetric radiation patterns.

Conclusions:

• The developed ANAU system enhances frequency upconversion by locally increasing excitation light and directing emission.
• This approach offers a new strategy for improving frequency upconversion efficiency and spatial control for diverse applications.
• The findings pave the way for more efficient and targeted applications of upconversion nanocrystals.