한국진공학회:학술대회논문집 (Proceedings of the Korean Vacuum Society Conference)
- 한국진공학회 2015년도 제49회 하계 정기학술대회 초록집
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- Pages.222.1-222.1
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- 2015
Irreversible luminescence from graphene quantum dots prepared by the chain of oxidation and reduction process
- Jang, Min-Ho (Department of Physics and Graphene Research Center of KI for the NanoCentury, KAIST) ;
- Ha, Hyun Dong (KAIST) ;
- Lee, Eui-Sup (Department of Chemical and Biomolecular Engineering and Institute for the BioCentury, KAIST) ;
- Kim, Yong-Hyun (Graduate School of Nanoscience and Technology, KAIST) ;
- Seo, Tae Seok (Graduate School of Nanoscience and Technology, KAIST) ;
- Cho, Yong-Hoon (Department of Physics and Graphene Research Center of KI for the NanoCentury, KAIST)
- 발행 : 2015.08.24
초록
Recently, graphene quantum dots (GQDs) have attracted great attention due to various properties including cost-effectiveness of synthesis, low toxicity, and high photostability. Nevertheless, the origins of photoluminescence (PL) from GQDs are unclear because of extrinsic states of the impurities, disorder structures, and oxygen-functional groups. Therefore, to utilize GQDs in various applications, their optical properties generated from the extrinsic states should be understood. In this work, we have focused on the effect of oxygen-functional groups in PL of the GQDs. The GQDs with nanoscale and single layer are synthesized by employing graphite nanoparticles (GNPs) with 4 nm. The series of GQDs with different amount of oxygen-functional groups were prepared by the chain of chemical oxidation and reduction process. The fabrication of a series of graphene oxide QDs (GOQDs) with different amounts of oxygen-contents is first reported by a direct oxidation route of GNPs. In addition, for preparing a series of reduced GOQDs (rGOQDs), we employed the conventional chemical reduction to GOQDs solution and controlled the amount of reduction agents. The GOQDs and rGOQDs showed irreversible PL properties even though both routes have similar amount of oxyen-functional groups. In the case of a series of GOQDs, the PL spectrum was clearly redshifted into blue and green-yellowish color. On the other hand, the PL spectrum of rGOQDs did not change significantly. By various optical measurement such as the PL excitation, UV-vis absorbance, and time-resolved PL, we could verify that their PL mechanisms of GOQDs and rGOQDs are closely associated with different atomic structures formed by chemical oxidation and reduction. Our study provides an important insights for understanding the optical properties of GQDs affected by oxygen-functional groups. [1]