Ultra‐Bright and Stable Pure Blue Light‐Emitting Diode from O, N Co‐Doped Carbon Dots

Abstract The pure blue light‐emitting diodes (LEDs) play a key role in the application of solid display and illumination. Most of pure blue LEDs reported so far, are based on semiconductor quantum dots and metal complex, involving heavy metal elements. Here, the fabrication of O, N co‐doped carbon dots (CDs) by a hydrothermal method from perylene‐3,4,9,10‐tetracarboxylic dianhydride and 2,3‐diaminophenazine is shown. These CDs show strong photoluminescence (PL) emission peaked at 447 nm (in ethanol) with absolute PL quantum yields of 88.9%. They are then doped into poly(vinyl carbazole) to form the active emission layer in the pure blue CDs LEDs. The electroluminescence emission of these CDs LEDs is centered at 452 nm with Commission Internationale d'Eclairage (CIE) coordinates of (0.14, 0.10). Moreover, the pure blue CDs LEDs show a high external quantum efficiency of 2.114%, high brightness of 648 cd m –2 , long half‐lifetime (T 50 ) of 200 h, and a favorable current efficiency of 2.2 cd A −1 . This work opens a new way to develop cost‐effective, environmental‐friendly, and high‐efficient metal‐free pure blue LEDs.