Freestanding Luminescent Films of Nitrogen-Rich Carbon Nanodots toward Large-Scale Phosphor-Based White-Light-Emitting Devices
Freestanding Luminescent Films of Nitrogen-Rich Carbon Nanodots toward Large-Scale Phosphor-Based White-Light-Emitting Devices
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DOI：
10.1021/cm400517g
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发表时间：
2013-05-14
影响因子：
8.6
通讯作者：
Rhee, Shi-Woo
中科院分区：
文献类型：
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作者：
Kwon, Woosung;Do, Sungan;Rhee, Shi-Woo
在这项工作中，通过聚丙烯酰胺的乳液模板碳化制备了富氮碳纳米点（CND）。通过红外、核磁共振和X射线光电子能谱研究了其形成机制和化学结构。透射电子显微镜还表明，所获得的 CND 具有发达的石墨结构和窄的尺寸分布，无需任何尺寸选择程序。我们通过改变聚合物的分子量来控制CND的尺寸，最终获得在紫外照射下呈现明亮可见光且量子产率高达40%的CND。鉴于 CND 在荧光粉应用中值得利用，我们制造了基于聚甲基丙烯酸甲酯基质的大规模 (20 X 20 cm) CND 独立式发光薄膜。聚合物基体不仅可以提供机械支撑，还可以分散CND以防止固态猝灭。对于实际应用，我们展示了由薄膜组成的白光 LED 作为颜色转换荧光粉和 InGaN 蓝光 LED 作为照明器。在实际操作条件下，此类白光 LED 的发射光谱没有表现出暂时的退化。这项研究提出了一种利用固态 CND 发光的有前途的方法，并为未来基于 CND 的固态照明系统提供了巨大的潜力。
In this work, nitrogen-rich carbon nanodots (CNDs) are prepared by the emulsion-templated carbonization of polyacrylamide. The formation mechanism and chemical structure are investigated by infrared, nuclear magnetic resonance, and X-ray photoelectron spectroscopies. Transmission electron microscopy also reveals that the obtained CNDs have well-developed graphitic structure and narrow size distribution without any size selection procedure. We vary the molecular weight of the polymer to control the size of the CNDs and finally obtain the CNDs rendering bright visible light under UV illumination with a high quantum yield of 40%. Given that the CNDs are worth utilizing in phosphor applications, we fabricate large-scale (20 X 20 cm) freestanding luminescent films of the CNDs based on a poly(methyl methacrylate) matrix. The polymer matrix can not only provide mechanical support but also disperse the CNDs to prevent solid-state quenching. For practical application, we demonstrate white LEDs consisting of the films as color converting phosphors and InGaN blue LEDs as illuminators. Such white LEDs exhibit no temporal degradation in the emission spectrum under practical operation conditions. This study would suggest a promising way to exploit the luminescence from solid-state CNDs and offer strong potential for future CND based solid-state lighting systems.