Making Graphene Luminescent by Oxygen Plasma Treatment

Gokus, Tobias; Nair, Rajeev; Bonetti, A.; Böhmler, Miriam; Lombardo, Antonio; Новоселов, К. С.; Geǐm, A. K.; Ferrari, Andrea C.; Hartschuh, Achim

doi:10.1021/nn9012753

Cited by 603 publications

(548 citation statements)

References 39 publications

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“…Moreover, excessive etching leads to additional defects and an increase of oxygen to carbon ratio in GQDs, resulting in the collapse of the 10-nm-sized sp 2 carbon structure in GQDs. 30,37,38 Similar results can also be observed for larger GQDs ( Figure S4). Furthermore, we investigated the influence of substrate functionalization on the PL emission characteristics of GQDs.…”

supporting

confidence: 83%

Uniform Graphene Quantum Dots Patterned from Self-Assembled Silica Nanodots

et al. 2012

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Graphene dots precisely controlled in size are interesting in nanoelectronics due to their quantum optical and electrical properties. However, most graphene quantum dot (GQD) research so far has been performed based on flaketype graphene reduced from graphene oxides. Consequently, it is extremely difficult to isolate the size effect of GQDs from the measured optical properties. Here, we report the sizecontrolled fabrication of uniform GQDs using self-assembled block copolymer (BCP) as an etch mask on graphene films grown by chemical vapor deposition (CVD). Electron microscope images show that as-prepared GQDs are composed of mono-or bilayer graphene with diameters of 10 and 20 nm, corresponding to the size of BCP nanospheres. In the measured photoluminescence (PL) spectra, the emission peak of the GQDs on the SiO 2 substrate is shown to be at ∼395 nm. The fabrication of GQDs was supported by the analysis of the Raman spectra and the observation of PL spectra after each fabrication step. Additionally, oxygen content in the GQDs is rationally controlled by additional air plasma treatment, which reveals the effect of oxygen content to the PL property.

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confidence: 83%

Uniform Graphene Quantum Dots Patterned from Self-Assembled Silica Nanodots

et al. 2012

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“…In principle, arbitrary pairs of functionalities can be attached onto the opposite sides of graphene to create various kinds of Janus graphene. For instance, fluorination and oxygenation reactions could be combined together to create Janus graphene of fluorine-graphene-oxygen 19,48 . XPS survey, the evolution of Raman spectra, and surface wettability measurements confirm that the fluorine and oxygen Figs S6,S7).…”

Section: Resultsmentioning

confidence: 99%

Janus graphene from asymmetric two-dimensional chemistry

et al. 2013

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Janus materials have distinct surfaces on their opposite faces. Graphene, a two-dimensional giant molecule, provides an excellent candidate to fabricate the thinnest Janus discs and study the asymmetric chemistry of atomic-thick nanomembranes using covalent chemical functionalisation. Here we present the first experimental realisation of nonsymmetrically modified single-layer graphene-Janus graphene-which is fabricated by a two-step surface covalent functionalisation assisted by a poly(methyl methacrylate)-mediated transfer approach. Four types of Janus graphene are produced by co-grafting of halogen and aryl/ oxygen-functional groups on each side. Chemical decorations on one side are found to be capable of affecting both chemical reactivity and physical wettability of the opposite side, indicative of communication between the two grafted groups. This novel asymmetric structure provides a platform for theoretical and experimental studies of two-dimensional chemistry and graphene devices with multiple functions.

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“…In direct-bandgap semiconductors, the radiative recombination of electrons and holes produces photons, and occurs much more efficiently than in indirect-bandgap semiconductors. The direct bandgaps of monolayer semiconducting TMDCs make them ideal candidates for the active light-emitting layer in future flexible optoelectronics, unlike graphene, which lacks a bandgap and requires chemical treatments to induce local bandgaps that photoluminesce 150,151 . Examples of electroluminescence in TMDCs include MoS 2 emitting light by electrical excitation through Au nano-contacts 152 , and electroluminescence from SnS 2 exfoliated from lithium intercalation and incorporated into a composite polymer matrix 56 .…”

Section: Optoelectronicsmentioning

confidence: 99%

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides

et al. 2012

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699M any two-dimensional (2D) materials exist in bulk form as stacks of strongly bonded layers with weak interlayer attraction, allowing exfoliation into individual, atomically thin layers 1 . The form receiving the most attention today is graphene, the monolayer counterpart of graphite. The electronic band structure of graphene has a linear dispersion near the K point, and charge carriers can be described as massless Dirac fermions, providing scientists with an abundance of new physics 2,3 . Graphene is a unique example of an extremely thin electrical and thermal conductor 4 , with high carrier mobility 5 , and surprising molecular barrier properties 6,7 .Many other 2D materials are known, such as the TMDCs 8,9 , transition metal oxides including titania-and perovskite-based oxides 10,11 , and graphene analogues such as boron nitride (BN) 12,13 . In particular, TMDCs show a wide range of electronic, optical, mechanical, chemical and thermal properties that have been studied by researchers for decades 9,14,15 . There is at present a resurgence of scientific and engineering interest in TMDCs in their atomically thin 2D forms because of recent advances in sample preparation, optical detection, transfer and manipulation of 2D materials, and physical understanding of 2D materials learned from graphene.The 2D exfoliated versions of TMDCs offer properties that are complementary to yet distinct from those in graphene. Graphene displays an exceptionally high carrier mobility exceeding 10 6 cm 2 V -1 s -1 at 2 K (ref. 16) and exceeding 10 5 cm 2 V -1 s -1 at room temperature for devices encapsulated in BN dielectric layers 5 ; because pristine graphene lacks a bandgap, however, fieldeffect transistors (FETs) made from graphene cannot be effectively switched off and have low on/off switching ratios. Bandgaps can be engineered in graphene using nanostructuring [17][18][19] , chemical functionalization 20 and applying a high electric field to bilayer graphene 21 , but these methods add complexity and diminish mobility. In contrast, several 2D TMDCs possess sizable bandgaps around 1-2 eV (refs 9,14), promising interesting new FET and optoelectronic devices.TMDCs are a class of materials with the formula MX 2 , where M is a transition metal element from group IV (Ti, Zr, Hf and so on), group V (for instance V, Nb or Ta) or group VI (Mo, W and so on), and X is a chalcogen (S, Se or Te). These materials form layered structures of the form X-M-X, with the chalcogen atoms in two hexagonal planes separated by a plane of metal atoms, as shown in Fig. 1a. Adjacent layers are weakly held together to form the bulk crystal in a variety of polytypes, which vary in stacking orders and metal atom coordination, as shown in Fig. 1e. The overall symmetry of TMDCs is hexagonal or rhombohedral, and the metal atoms have octahedral or trigonal prismatic coordination. The electronic properties of TMDCs range from metallic to semiconducting, as summarized in Table 1. There are also TMDCs that exhibit exotic behaviours such as charge density waves ...

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Making Graphene Luminescent by Oxygen Plasma Treatment

Cited by 603 publications

References 39 publications

Uniform Graphene Quantum Dots Patterned from Self-Assembled Silica Nanodots

Uniform Graphene Quantum Dots Patterned from Self-Assembled Silica Nanodots

Janus graphene from asymmetric two-dimensional chemistry

Electronics and optoelectronics of two-dimensional transition metal dichalcogenides

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