Tailoring Multifunctional Carbon Dots via Precursor Stoichiometry: Switching Between Solid-State Fluorescence and...

Area of Science:

• Materials Science
• Nanotechnology
• Photophysics

Background:

• Carbon dots (CDs) exhibit limited solid-state optical properties due to aggregation-caused quenching (ACQ) and narrow absorption.
• Precise control over CD surface chemistry and aggregation is crucial for advanced applications.

Purpose of the Study:

• To establish a framework linking precursor stoichiometry, CD surface chemistry, and aggregation behavior.
• To engineer CDs with tunable solid-state optical properties, including fluorescence and broadband absorption.

Main Methods:

• Synthesizing CDs by varying the molar ratio of 2,3-diaminonaphthalene to o-phthalaldehyde.
• Investigating the self-assembly and aggregation geometry of CDs based on surface chemistry.
• Characterizing the solid-state optical properties (fluorescence, absorption) of engineered CDs.

Main Results:

• Aldehyde-rich CDs self-assemble into ordered, layered structures via hydrogen bonding, enabling red solid-state fluorescence (SSF) by suppressing π-π stacking.
• Amine-rich CDs form compact, spherical aggregates through π-π stacking, leading to broadband visible absorption via intermolecular charge transfer (ICT).
• Precursor stoichiometry effectively dictates CD surface functionality, aggregation, and resulting optical properties.

Conclusions:

• A general design principle is established: aldehyde-rich surfaces promote SSF, while amine-rich surfaces confer broadband absorption and photothermal capability.
• Precursor stoichiometry is a powerful tool for directing CD aggregation and developing multifunctional CD-based materials.
• This work provides a unified platform for designing CDs with tailored solid-state optical properties.