Matrix-free, color-tunable carbon quantum dots with solid-state emission for white LEDs

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Solid-state photoluminescence quenching is a significant hurdle for carbon quantum dots (CQDs) in optoelectronic devices.
• Developing CQDs with inherent resistance to quenching is crucial for their practical application.

Purpose of the Study:

• To synthesize self-quenching-resistant, color-tunable carbon quantum dots (CQDs) using a facile one-step microwave method.
• To investigate the aggregation-induced redshift mechanism for tunable photoluminescence.
• To demonstrate the potential of these CQDs in solid-state lighting applications.

Main Methods:

• One-step microwave synthesis of CQDs from phloroglucinol and urea.
• Control of reactant ratios and microwave power to tune photoluminescence color (blue to yellow).
• Fabrication of dual-color and white light-emitting diodes (LEDs).

Main Results:

• Achieved tunable photoluminescence from 395 nm (blue) to 590 nm (yellow) via aggregation-induced redshift.
• Obtained high solid-state quantum yields: 45.2% (blue) and 52.0% (yellow).
• Demonstrated excellent photostability (>90.5% retention after 90 min UV exposure) and LED performance (55.8 lm/W efficacy, 72 CRI, 85% flux retention).

Conclusions:

• A matrix-free microwave synthesis effectively overcomes solid-state quenching in CQDs.
• The developed CQDs are highly promising for advanced solid-state lighting due to their tunable color, high efficiency, and stability.
• This approach paves the way for practical applications of CQDs in optoelectronics.