Self-Quenching-Resistant Red Emissive Carbon Dots with High Stability for Warm White Light-Emitting Diodes with a High Color Rendering Index

Due to the excellent characteristics of energy-saving, environmentally friendly and long-life, the solid-state lighting based on white light-emitting diodes (WLEDs) is an emerging technology to replace traditional lighting solutions. However, the lack of red component of the most established method for fabricating commercial WLEDs results in high correlated color temperature (CCT) and low color rendering index (CRI). Herein, red-emitting carbon dots (R-CDs) with self-quenching-resistant property are synthesized using melamine and dithiosalicylic acid as precursors. In addition, R-CDs exhibit high thermal and photostability under high temperature and strong blue light irradiation. On the basis of the unique features of R-CDs, a WLED is fabricated by combining a blue-LED chip with commercial Ce3+:Y3Al5O12 and R-CDs phosphors, which exhibits warm white light with a color coordinate of (0.41, 0.38), a high CRI of 92.7 and a CCT of 3827 K. Besides, the WLED exhibits good optical stability upon the increase of drive current from 20 to 100 mA. The results suggest R-CDs can be used as a color converter to fabricate high-quality warm WLEDs.