Dai Wubin, Lei Yifeng, Xu Man, Zhao Pei, Zhang Zhanhui, Zhou Jia
Key Laboratory for Green Chemical Process of Ministry of Education, Hubei Key Laboratory of Plasma Chemistry and Advanced Materials, School of Material Science and Engineering, Wuhan Institute of Technology, Wuhan, 430205, Hubei, China.
The Institute of Technological Science, School of Power and Mechanical Engineering, Wuhan University, Wuhan, 430072, Hubei, China.
Sci Rep. 2017 Oct 9;7(1):12872. doi: 10.1038/s41598-017-13404-1.
Rare-earth (RE) based phosphors are attractive due to their potential applications. However, owing to the resource issue, these kinds of phosphors are expensive and costly. On the contrary, as for phosphor-convert white light-emitting-diodes (pc-WLEDs), a solution-processed tunable warm white emission LED composite is fabricated in this study under single excitation, with both RE free phosphors graphene quantum dots (GQDs) and Copper-Cysteamine (Cu-Cy). By using microwave-assisted wet-chemical method and with graphite as raw material, cold white fluorescence of the GQDs is obtained. Cu-Cy which shows intense photoluminescence in the red region has the structure where both the thio and amine groups connected with copper and forming cysteamine. Warm white light is achieved by mixing the two self-activated RE free phosphors at the weight ratio of 1: 1.7 under the excitation at 365 nm. The designed optimal LED device has the properties of CIE (x, y) = (0.341, 0.327), T = 4436 K, R = 87.9 EQE = 0.31%. The experimental results demonstrate that RE free phosphor(s) excited under a single chip can open up a new avenue to develop much lower device for warm WLEDs.
基于稀土（RE）的磷光体因其潜在应用而备受关注。然而，由于资源问题，这类磷光体价格昂贵。相反，对于磷光体转换白光发光二极管（pc-WLEDs），本研究在单激发下制备了一种溶液处理的可调谐暖白光发射LED复合材料，其中不含稀土的磷光体包括石墨烯量子点（GQDs）和铜-半胱胺（Cu-Cy）。通过微波辅助湿化学方法，以石墨为原料，获得了GQDs的冷白色荧光。在红色区域显示出强烈光致发光的Cu-Cy具有硫醇和胺基都与铜相连并形成半胱胺的结构。通过在365nm激发下将两种自激活的无稀土磷光体按1:1.7的重量比混合，实现了暖白光。所设计的最佳LED器件具有CIE（x，y）=（0.341，0.327）、T = 4436K、R = 87.9、EQE = 0.31%的性能。实验结果表明，在单个芯片激发下的无稀土磷光体可为开发更低成本的暖WLED器件开辟一条新途径。
