Highly stable yellow-emitting fluorescent film based on graphene quantum dots for white laser-emitting devices

Green-emitting graphene quantum dots (GQDs) with a high crystallization degree were prepared by a two-step solvothermal method . Owing to the co-doping of nitrogen and oxygen, carbonyl and amide groups were introduced into GQDs. The quantum yield (QY) of GQD solution is up to 47.09%, which is higher than that of other GQDs synthesized by top-down methods. Since GQD solution exhibits concentration-dependent photoluminescence (PL) properties, green, yellow, and orange emissions were realized by adjusting GQD concentration. A high concentration (no less than 6.0 mg mL −1 ) GQD solution was mixed with KH-792 to form a yellow-emitting fluorescent film with an excellent fluorescence and thermal stability, which was used as color converters and combined with 405 nm laser diodes (LDs) to realize the devices with white laser-emitting. The Commission Internationale de L'Eclairage (CIE) coordinate of the laser device is (0.34, 0.39), the correlated color temperature (CCT) is 5288 K, and the color rendering index (CRI) is 70. This work provides an advanced way for the development of laser fluorescent materials.