Cited 4 time in webofscience Cited 5 time in scopus

Size and pH dependent photoluminescence of graphene quantum dots with low oxygen content

Title
Size and pH dependent photoluminescence of graphene quantum dots with low oxygen content
Authors
Song, SH[Song, Sung-Ho]Jang, M[Jang, Minho]Yoon, H[Yoon, Hyewon]Cho, YH[Cho, Yong-Hoon]Jeon, S[Jeon, Seokwoo]Kim, BH[Kim, Bo-Hyun]
DGIST Authors
Kim, BH[Kim, Bo-Hyun]
Issue Date
2016
Citation
RSC Advances, 6(100), 97990-97994
Type
Article
Article Type
Article
Keywords
Auger Electron SpectroscopyCharacteristic PropertiesDefectsElectron SpectroscopyElectronic StructureEmission PeaksEnergy GapExcitation WavelengthFunctionalizationsGrapheneGraphene OxidesLow Oxygen ContentsNanocrystalsOptical SpectroscopicOxygenPhotoluminescencePhotophysical PropertiesSemiconductor Quantum DotsSpectroscopic Analysis
ISSN
2046-2069
Abstract
The photoluminescence of graphene quantum dots (GQDs) is rigorously investigated due to their potential applications. However, GQDs from graphene oxide are inherently embedded with non-negligible defects and oxygen grafted onto the edge and basal plane, which induce a change of innate electronic structure in the GQDs. Thus, graphene oxide based GQDs can misrepresent the characteristic properties of primitive GQDs. Here we report the size and pH dependent photophysical properties of GQDs that minimize the content of oxygen and defects. From auger electron spectroscopy, the oxygen content of the GQDs with two different lateral sizes (∼2 nm and ∼18 nm) was probed and found to be ∼5% and ∼8%, respectively. Two common photoluminescence (PL) peaks were observed at 436 nm (the intrinsic bandgap) and 487 nm (the extrinsic bandgap) for both GQDs. The characteristic PL properties in extrinsic and intrinsic bandgaps examined by optical spectroscopic methods show that the emission peak was red-shifted and that the peak width was widened as the size increased. Moreover, the PL lifetime and intensity were not only reversibly changed by pH but also depended on the excitation wavelength. This is in line with our previous report and is ascribed to the size variation of sp2 subdomains and edge functionalization. © The Royal Society of Chemistry 2016.
URI
http://hdl.handle.net/20.500.11750/2311
DOI
10.1039/c6ra21651j
Publisher
Royal Society of Chemistry
Files:
There are no files associated with this item.
Collection:
School of Undergraduate Studies1. Journal Articles


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