Direct blending of multicolor carbon quantum dots into fluorescent films for white light emitting diodes with an adjustable correlated color temperature

White Eight-emitting diodes (WLEDs) with a high color rendering index (CRI) and an adjustabLe correlated color temperature (CCT) are of great importance in a wide range of fields. We report an efficient method to fabricate WLEDs with prominent CCT performance by the combination of multi-colour carbon quantum dots (CQDs). Long-wavelength CQDs with green, yellow and orange emission (denoted as G-, Y-, and 0-CQDs, respectively) were obtained by a one-pot soLvothermaL reaction between phthaLic acid and o-phenyEenediamine followed by precise separation by silica column chromatography. Systematic investigation and detailed characterization demonstrate that G- and Y-CQDs emit mainly due to the quantum size effect, while the photoluminescence emission of 0-CQDs is mainly derived from surface defect states formed by surface oxidation. Subsequently, solid-state Luminous red-green-blue CQD films obtained by using tri-functional blue emitting CQDs (phosphors, dispersants and curing agents) Lead to UV-pumped WLEDs with good color stability and a high CRI (83-88) as well as an adjustabLe CCT (3466-7368 K). This work has opened up new avenues for the development of [ow-cost, environmentally-friendly and high-performance CQD phosphor-based WLEDs.