Ultra-wideband-responsive photon conversion through co-sensitization in lanthanide nanocrystals

Area of Science:

• Materials Science
• Nanotechnology
• Photonics

Background:

• Lanthanide nanocrystals offer unique upconversion/downshifting properties for biomedical and photonic uses.
• Current methods require high-energy lasers at specific wavelengths, limiting excitation flexibility.

Purpose of the Study:

• To overcome excitation wavelength limitations in lanthanide nanocrystals.
• To develop a co-sensitization strategy for ultrawide excitation bands.
• To enable tunable fluorescence for advanced applications.

Main Methods:

• Employed neodymium (Nd³⁺) and holmium (Ho³⁺) as co-sensitizers with complementary UV-to-IR absorption.
• Engineered symmetric penta-layer core-shell nanostructures.
• Incorporated various activators (Er³⁺, Ho³⁺, Pr³⁺, Tm³⁺) for tunable fluorescence.

Main Results:

• Achieved ultrawide excitation bands through co-sensitization.
• Demonstrated tunable fluorescence in visible and second near-infrared (NIR-II) windows.
• Confirmed directional energy transfer from sensitizers to activators via ytterbium (Yb³⁺).
• Validated nanocrystals for low-powered, whole-body mouse angiography (SNR 12.3) and excitation-regulated encryption.

Conclusions:

• Co-sensitization strategy breaks excitation limitations of lanthanide nanocrystals.
• Enables multidirectional photon conversion and excitation-bandwidth-regulated fluorescence.
• Opens new avenues for biomedical imaging and photonic devices.