Gram-scale synthesis and optical properties of novel tunable solid-state fluorescent carbon dots with self-quenching-resistance for full-carbon-based w-LEDs

The propensity of carbon dots (CDs) to undergo significant self-quenching in the solid state, whether due to excessive resonance energy transfer or direct molecule collision, has significantly limited their application in light-emitting diodes (LEDs). However, incorporating electron-deficient boron atoms, guanidine functional groups, and boron hydroxyl groups proves advantageous in forming a hydrogen bond structure network. This network effectively suppresses the self-quenching phenomenon observed in solid CDs, thereby enhancing their potential for use in LEDs. Therefore, on this basis, a series of multicolor tunable solid-state fluorescent CDs were obtained, and their formation mechanism was discussed. The structure and morphology of the prepared series of multicolor tunable CDs were also characterized. The photoluminescence quantum yield (PLQY) of B-CD, Y-CD, and R-CD is 34.3 %, 23.7 %, and 20.5 %, respectively. The prepared series of CDs were used to successfully package the red, blue, and yellow monochromatic LEDs. By adjusting the ratio of CDs of different colors, a single matrix white-LEDs (w-LEDs), two primary colors w-LEDs, and the full-carbon-based w-LED of three primary colors are also obtained. The correlated color temperature of the above three w-LEDs is 7277, 3957, and 5040 K, the Color Rendering Index is 88, 91, and 92, and color coordinates are (0.302, 0.319), (0.376, 0.355), and (0.344, 0.354), respectively. It is demonstrated that CDs are a promising material in the solid-state lighting field.