Synthesis of Longer‐Wavelength‐Emissive Carbon Quantum Dots for WLEDs and Investigation of Their Photoluminescence Properties

Abstract The synthesis of highly fluorescent longer wavelength emissive carbon quantum dots (CQDs) is still a great challenge as well as an important issue, hindering its application in white light emitting diode (WLED). Herein, we have demonstrated a simple one‐pot solvothermal route for the synthesis of nitrogen and sulphur co‐doped CQDs using pyromellitic acid (PA), diethylenetriamine (DETA) and thiourea. At the specific molar ratio of the precursors, the orange color emissive CQDs (O‐CQDs) are synthesized and possess longer wavelength emission (611 nm). Additionally, O‐CQDs exhibits temperature and pH dependent photoluminescence (PL) properties. The O‐CQDs shows color correlated temperature (CCT) of 1745 K with high color purity of 98%. Simultaneously, as‐synthesized nitrogen and sulphur co‐doped CQDs shows concentration‐dependent PL properties, which display not only the brightness with stable orange color but also possess range of multicolour emission at different PL excitation. Solid host matrix of O‐CQDs is fabricated with poly‐(methyl methacrylate) (PMMA) chloroform solution and orange emissive property is investigated by wrapping the film over LED (InGaN) bulb. These studies will open up new opportunities to explore the tunable optical properties of carbon quantum dots and its applications in WLED devices.