Bright white light emitting diodes based on sustainable graphene quantum dots derived from Moringa oleifera leaves as photo-converter layer

IF 5.8 3区材料科学 Q2 CHEMISTRY, MULTIDISCIPLINARY

Carbon Letters Pub Date : 2025-06-13 DOI:10.1007/s42823-025-00932-4

F. S. Abd El-kawy, S. Hammad, H. Talaat, G. Bacher, M. Ghali

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引用次数: 0

Abstract

The avenue to synthesize eco-friendly and high-performing warm-white light emitting diodes (WLEDs) using quantum-dots for color conversion is challenging. Here, the graphene quantum dots (GQDs) are synthesized from Moringa oleifera leaves without the need of any organic solvents or reducing agents by a one-pot hydrothermal method and utilized for the design of efficient warm WLEDs. The photoluminescence of the obtained GQDs is found to be red-shifted as the excitation wavelength increases. This is ascribed to an excitation of multiple transitions due to various surface traps related to surface amino and oxygen functionalized groups as revealed from X-ray-photoelectron–spectroscopy and FTIR results. Three different concentrations of GQDs are embedded in polyvinyl-alcohol matrix acting as color-converters for the design of WLED devices. By increasing the GQDs concentration, the color correlated temperatures are tuned from 3804 to 2593 K and the luminous efficacy from 39.3 to 71.69 lm/W. Moreover, the chromaticity coordinates of the devices are shifted from (0.3825, 0.3665) to (0.4807, 0.4478). The brightness of the fabricated devices based on these green-GQDs are comparable with those of warm LEDs prepared from chemically synthesized graphene and carbon dots and can be suitable for indoor lighting applications.

Graphical abstract

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基于辣木叶中提取的可持续石墨烯量子点作为光转换器层的明亮白光发光二极管

利用量子点进行颜色转换，合成环保、高性能的暖白光发光二极管（wled）的途径具有挑战性。本研究以辣木叶为原料，采用一锅水热法合成石墨烯量子点（GQDs），无需任何有机溶剂或还原剂，并用于设计高效的暖式led。所得GQDs的光致发光随激发波长的增加而发生红移。这是由于x射线光电子能谱和FTIR结果显示的与表面氨基和氧官能团相关的各种表面陷阱引起的多重跃迁激发。将三种不同浓度的GQDs嵌入聚乙烯醇基质中，作为WLED器件的颜色转换器。通过提高GQDs浓度，可将色相关温度从3804调至2593 K，光效从39.3调至71.69 lm/W。此外，器件的色度坐标从（0.3825,0.3665）移动到（0.4807,0.4478）。基于这些绿色gqds制造的器件的亮度与化学合成石墨烯和碳点制备的暖led相当，可以适用于室内照明应用。图形抽象

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Carbon Letters CHEMISTRY, MULTIDISCIPLINARY-MATERIALS SCIENCE, MULTIDISCIPLINARY

CiteScore

7.30

自引率

20.00%

发文量

118

期刊介绍： Carbon Letters aims to be a comprehensive journal with complete coverage of carbon materials and carbon-rich molecules. These materials range from, but are not limited to, diamond and graphite through chars, semicokes, mesophase substances, carbon fibers, carbon nanotubes, graphenes, carbon blacks, activated carbons, pyrolytic carbons, glass-like carbons, etc. Papers on the secondary production of new carbon and composite materials from the above mentioned various carbons are within the scope of the journal. Papers on organic substances, including coals, will be considered only if the research has close relation to the resulting carbon materials. Carbon Letters also seeks to keep abreast of new developments in their specialist fields and to unite in finding alternative energy solutions to current issues such as the greenhouse effect and the depletion of the ozone layer. The renewable energy basics, energy storage and conversion, solar energy, wind energy, water energy, nuclear energy, biomass energy, hydrogen production technology, and other clean energy technologies are also within the scope of the journal. Carbon Letters invites original reports of fundamental research in all branches of the theory and practice of carbon science and technology.