Solid-state Fluorescence from Carbon Dots Widely Tunable from Blue to Deep Red through Surface Ligand Modulation

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Carbon dots (CDs) exhibit promising fluorescent and electronic properties.
• Aggregation-caused quenching (ACQ) hinders the application of CDs in solid-state devices, particularly colored displays.
• Developing CDs with tunable solid-state fluorescence (SSF) is challenging but crucial for advanced applications.

Purpose of the Study:

• To engineer carbon dots with broad, tunable solid-state fluorescence (SSF) from blue to deep red.
• To investigate the structure-property relationships governing the emission characteristics of these SSF CDs.
• To demonstrate the potential of these SSF CDs in practical applications like 3D-printed optical devices.

Main Methods:

• Surface ligand modulation was employed to synthesize SSF CDs.
• In-depth structure-property studies were conducted to understand emission mechanisms.
• Photodynamic characterizations were performed to analyze emission wavelength switching.
• Three-dimensional printing was utilized for device fabrication.

Main Results:

• Achieved SSF CDs with an emission-color span of nearly 300 nm (blue to deep red).
• Identified intra- and inter-molecular hydrogen bonding as key factors influencing emission in the aggregated state.
• Demonstrated smooth switching of emission wavelengths by altering ligand conjugation.
• Successfully created 3D-printed emissive objects, showcasing commercial potential.

Conclusions:

• Surface ligand modulation is an effective strategy for achieving color-tunable SSF in carbon dots.
• Hydrogen bonding plays a critical role in the solid-state fluorescence properties of CDs.
• The developed CDs hold significant promise for applications in optical lamps and colored displays.