Customized NIR-II Dual-Phase Carbon Dots: Elucidating the Emission Mechanism for Smart Photonic Applications

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Carbon dots (CDs) offer potential for advanced applications due to their unique photoluminescence (PL) properties.
• Dual-phase PL in the second near-infrared window (NIR-II) is desirable for encryption and bioimaging but lacks reliable design strategies.

Purpose of the Study:

• To develop high-brightness, dual-phase NIR-II PL carbon dots (NIR-CDs) using innovative design strategies.
• To investigate the structure-property relationships governing the dual-phase PL emission.

Main Methods:

• Synthesis of NIR-CDs with a core-shell structure.
• Characterization of optical properties, including fluorescence quantum yield (QY) and stability.
• Evaluation of NIR-CDs in information encryption and bioimaging scenarios.

Main Results:

• Successfully synthesized NIR-CDs with a core-shell structure and donor-acceptor interactions.
• Achieved high fluorescence QY (up to 5.91% at 920 nm) and excellent stability.
• Demonstrated dual-phase PL at 920 nm and 960 nm (solid-state QY of 3.82%) enabling multilevel encryption and clear imaging through tissue.

Conclusions:

• The novel NIR-CDs exhibit promising dual-phase NIR-II PL for advanced information encryption and bioimaging.
• The core-shell design strategy effectively induces charge-transfer states for high brightness and stability.
• NIR-CDs show potential for anti-counterfeiting, encryption, and in vivo sensing applications.