Solid-state red emissive carbon dots based on high boiling point solvents for white light-emitting diodes

Area of Science:

• Materials Science
• Nanotechnology
• Optoelectronics

Background:

• Carbon dots (CDs) are versatile nanomaterials with tunable optical properties.
• Developing efficient and stable red-emissive CDs is crucial for advanced lighting applications.
• Existing synthesis methods can be complex and time-consuming.

Purpose of the Study:

• To develop a simple, rapid, and efficient method for synthesizing solid-state red emissive carbon dots (R-CDs).
• To investigate the impact of precursor ratios and solvent systems on R-CD properties.
• To evaluate the performance of R-CDs in solid-state lighting applications, particularly white LEDs.

Main Methods:

• Microwave-assisted synthesis using phloroglucinol, urea, and ammonium fluoride.
• Optimization of precursor molar ratios and solvent compositions (e.g., N,N-dimethylformamide/water, formamide/water).
• Characterization of R-CDs' optical properties, stability (UV exposure, thermal), and application in light-emitting diodes (LEDs).

Main Results:

• A one-step microwave method successfully synthesized stable R-CDs.
• Optimal conditions yielded R-CDs emitting at 625 nm (3:1:6 molar ratio, 50% DMF/water, 15 min) or 640 nm (formamide/water, 3 min).
• R-CDs demonstrated excellent photostability (>96% fluorescence retention) and thermal stability (<5% weight loss at 200°C).
• R-CDs were integrated into red LEDs and white LEDs, achieving high color rendering indexes (91-92).

Conclusions:

• The developed microwave-assisted method provides an efficient route to solid-state R-CDs.
• The synthesized R-CDs exhibit superior stability and tunable emission properties.
• These R-CDs are highly suitable for fabricating high-performance white LEDs, advancing solid-state lighting technology.