Bright White Upconversion Luminescence under Low Excitation Power Density with Sensitive Temperature Monitoring.

Area of Science:

• Materials Science
• Nanotechnology
• Photonics

Background:

• Efficient white upconversion luminescence (UCL) at the nanoscale is crucial for advanced imaging and sensing.
• Current methods face challenges in achieving high-intensity white UCL.

Purpose of the Study:

• To develop a method for ultrastrong white UCL using core/multishell nanoparticles.
• To enhance nanoscale photon sources for improved imaging and sensing capabilities.

Main Methods:

• Fabrication of core/multishell nanoparticles (NaYF4@NaYbF4:Tm@NaYF4@NaYbF4:Er@NaYF4) with spatially separated Yb3+/Tm3+ and Yb3+/Er3+ ion pairs.
• Utilizing an inert NaYF4 interlayer to control energy transfer and suppress nonradiative relaxation.
• Optimizing inert core size to 85 nm to maximize excitation volume.

Main Results:

• Achieved white UCL intensity 37.1 times greater than core-only nanoparticles.
• Demonstrated precise control over luminescence intensity and strong white light emission.
• Observed enhanced thermal sensitivity (2.5x higher) due to lattice distortion.

Conclusions:

• The proposed core/multishell nanoparticle design enables ultrastrong white UCL.
• The system exhibits dual functionality for both luminescence and thermometry.
• This advancement offers a promising single-nanomaterial solution for advanced applications.