N-doped carbon dots for deep-blue emission and CD-LED device with 402 nm electroluminescence

and an external quantum efficiency of 2.58%, with Commission Internationale de l'Éclairage (CIE) coordinates of (0.15, 0.08). All these device parameters are better than most of the previously reported values. Hence, solution-processed pyrazine-based nitrogen-doped CDs prove to be an ideal candidate for low-cost and efficient blue LEDs.