Engineering Er³⁺-sensitized nanocrystals to enhance NIR II-responsive upconversion luminescence

Area of Science:

• Materials Science
• Nanotechnology
• Photonics

Background:

• Upconversion nanostructures are crucial for bio-imaging and anti-counterfeiting.
• Achieving high efficiency in the second near-infrared window (NIR II) remains a challenge.
• Er³⁺-sensitized systems show promise but require improved emission.

Purpose of the Study:

• To design a novel Er³⁺-sensitized core-shell-shell nanostructure.
• To enhance near-infrared II (NIR II) upconversion luminescence efficiency.
• To explore applications in bio-imaging and anti-counterfeiting.

Main Methods:

• Construction of a Yb³⁺-enriched core-shell-shell upconversion nanostructure.
• Utilizing interfacial energy transfer (IET) from Er³⁺ shell to Yb³⁺ core.
• Minimizing energy back-transfer and optimizing activator ion concentration.

Main Results:

• Achieved a remarkable enhancement in NIR II emission at 1000 nm.
• Obtained a high quantum yield (QY) of 11.5% for NIR II emission.
• Demonstrated efficient 1550 nm-responsive visible and NIR upconversion emissions by co-doping.

Conclusions:

• The novel nanostructure design effectively traps and locks excitation energy.
• This approach significantly boosts NIR II upconversion luminescence efficiency.
• The findings offer a new strategy for developing practical upconversion-based technologies.