Application of one-step synthesized broadband carbon quantum dots in white light-emitting diodes

In recent years, white light-emitting diodes (W-LEDs) based on carbon quantum dots (CQDs) have received widespread attention, with most researchers fabricating W-LEDs using multi-color CQDs. In this study, white CQDs (W-CQDs) were synthesized via a one-step solvothermal method using o-phenylenediamine and 1,2,4-benzenetricarboxylic acid as the carbon precursors and absolute ethanol as the solvent. The morphology, size, surface functional groups, composition, and crystal structure of W-CQDs were characterized using transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and X-ray diffraction techniques. The wide bandgap and broad-spectrum luminescence properties of W-CQDs demonstrate their potential application in W-LEDs. We employed a double-layer encapsulation method using polyvinyl alcohol and epoxy resin adhesives A and B to fabricate W-LED devices based on W-CQDs. These devices exhibit color coordinates of (0.32, 0.38), a color rendering index of 88, and a correlated color temperature of 5656 K. This study provides a simple method to synthesise CQDs for application in W-LED devices while extending their operational lifespan.