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.

中文翻译：

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用于WLED的长波长发射碳量子点的合成及其光致发光性能的研究

高荧光长波长发射碳量子点（CQDs）的合成仍然是一个巨大的挑战，也是一个重要的问题，阻碍了其在白光发光二极管（WLED）中的应用。在本文中，我们展示了一种简单的单锅溶剂热路线，可使用均苯四酸（PA），二亚乙基三胺（DETA）和硫脲来合成氮和硫共掺杂的CQD。在前体的特定摩尔比下，合成了橙色发射CQD（O-CQD），并具有更长的波长发射（611 nm）。此外，O-CQD表现出温度和pH依赖的光致发光（PL）特性。O-CQD显示1745 K的色温（CCT），色纯度高达98％。同时，氮和硫共掺杂的CQD表现出浓度依赖性的PL特性，它不仅显示具有稳定橙色的亮度，而且还具有在不同PL激发下的多色发射范围。O-CQD的固态主体基质是用聚甲基丙烯酸甲酯（PMMA）氯仿溶液制成的，并且通过将薄膜包裹在LED（InGaN）灯泡上来研究其橙色发光性能。这些研究将为探索碳量子点的可调光学特性及其在WLED器件中的应用提供新的机会。