Reliable determination of the few‐layer graphene oxide thickness using Raman spectroscopy

Kostiuk, Dmytro; Bodík, Michal; Šiffalovič, Peter; Jergel, M.; Halahovets, Yuriy; Hodas, Martin; Pelletta, Marco; Pelach, Michal; Hulman, Martin; Špitálský, Zdenko; Omastová, Mária; Majková, E.

doi:10.1002/jrs.4843

Cited by 53 publications

(45 citation statements)

References 48 publications

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“…Similarly to graphene, GO is also highly transparent in the visible range, with the experimentally measured optical contrast of 3.6% on 300 nm SiO2/Si using a 100× objective [38]. Applying the same methodology as for graphene, we found that the stratified heterostructures can also significantly enhance the optical visibility modes are not sensitive to the GO thickness but their intensities increase linearly with the number of layers, which is consistent with previous studies [38,39]. Figure 5e shows the AFM phase image of a monolayer region marked in figure 5b.…”

Section: Resultssupporting

confidence: 89%

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Optimising the visibility of graphene and graphene oxide on gold with multilayer heterostructures

et al. 2018

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Metals have been increasingly used as substrates in devices based on two-dimensional (2D) materials. However, the high reflectivity of bulk metals results in low optical contrast (<3%) and therefore poor visibility of transparent mono- and few-layer 2D materials on these surfaces. Here we demonstrate that by engineering the complex reflectivity of a purpose-designed multilayer heterostructure composed of thin Au films (2-8 nm) on SiO/Si substrate, the optical contrast of graphene and graphene oxide (GO) can be significantly enhanced in comparison to bulk Au, up to about 3 and 5 times, respectively. In particular, we achieved ∼17% optical contrast for monolayer GO, which is even 2 times higher than that on bare SiO/Si substrate. The experimental results are in good agreement with theoretical simulations. This concept is demonstrated for Au, but the methodology is applicable to other metals and can be adopted to design a variety of high-contrast metallic substrates. This will facilitate research and applications of 2D materials in areas such as plasmonics, photonics, catalysis and sensors.

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Section: Resultssupporting

confidence: 89%

“…figure S4. There is also a variation of monolayer GO ñ and d in literature: n = 1.2 -2.0, κ = 0.1 -0.7, and d = 0.7 -1.5 nm [37][38][39][40], most likely caused by the variability of the oxygen-containing groups of GO.…”

Section: Optical Contrast Simulationmentioning

confidence: 95%

Optimising the visibility of graphene and graphene oxide on gold with multilayer heterostructures

et al. 2018

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“…Figure (b) presents the Raman map plotting the ratio I D / I G between integrated intensities associated with the disorder‐induced D band and the graphite‐like G band, centred at ∼1340 and ∼1600 cm −1 , respectively (Fig. (d)) . Note that the significant breadth of the D band is directly related to the presence oxygen‐induced defects in G‐O and is fully congruent with the spectral lineshape reported by the G‐O manufacturer (see Section 2.1).…”

Section: Materials Characterization Methodssupporting

confidence: 73%

Electro‐mechanical properties of inkjet‐printed graphene oxide nanosheets

Nikolaou

Hallil

Conedera

et al. 2016

Physica Status Solidi (a)

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This study deals with the deposition of graphene oxide (G‐O) thin films by inkjet printing method on Love wave devices, forming up G‐O nanosheets in between the inter‐digitated transducers (IDTs) of the device. Experimental results were compared with 3D finite element calculations. Enhanced properties were observed by amalgamating ultra‐thin G‐O films with SiO2 and lead to optimized guided surface acoustic wave propagation. The structural model of the G‐O films provided useful information regarding the Young and the Shear modulus of the device, which are found near 470 and 196 GPa, respectively. The resulting Maxwelian viscoelastic components of G‐O sheets were compared theoretically and experimentally to each other based on the providing losses on the Love wave devices through the scattering parameters (S‐parameters). Similarly, the theoretical and experimental resonance frequency data showed a very good agreement. This behavior is attributed to the different mechanisms, thus combining the viscoelastic and gravimetric effects of the G‐O on the Love wave devices. Finally, The G‐O film was characterized using colocalized AFM/Raman imaging in order to assess its roughness and chemical homogeneity.

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“…The presence of typical D (Disorder) and G (Graphitic) vibrational bands of GO in the Raman spectrum of c‐TiO 2 /m‐TiO 2 /GO‐Li carried out by focusing the laser beam onto the m‐TiO 2 layer confirms the interpenetration of GO‐Li in the mesoporous layer.…”

Section: Resultsmentioning

confidence: 70%

Efficiency and Stability Enhancement in Perovskite Solar Cells by Inserting Lithium‐Neutralized Graphene Oxide as Electron Transporting Layer

Agresti

Pescetelli

Cinà

et al. 2016

Adv Funct Materials

190

176

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wileyonlinelibrary.comthe theoretical values, [ 9 ] further work is needed to increase the fi ll factor (FF) that today remains the bottleneck for the PCE enhancement. In this context, the optimization of interfaces between absorber, carrier transport layers, and electrode contact layers is crucial for an effi cient carrier transport. Thus, to improve the PCE of the PSCs, three main aspects need to be taken into account: the band alignment, the interface structure, and its passivation. [ 9 ] Furthermore, it must be taken into account that the injection times of electrons and holes in PSCs have been measured to be 0.4 and 0.6 ns, respectively, which are still orders of magnitude longer than the hot carrier cooling (or thermalization) time (≈0.4 ps). [ 10 ] Thus, a large amount of the converted photon energy is wasted in the thermalization process and in the carrier trapping. In this context, several materials have been proposed to facilitate electron/ hole extractions, including fullerene, [ 11 ] graphene, [ 12 ] or core/ shell metal nanoparticles. [ 13 ] Although graphene-based materials have been demonstrated to improve the performance and stability of organic and hybrid photovoltaic devices as recently reviewed by Singh and Nalwa, [ 14,15 ] a direct evidence is yet to be obtained regarding their role as a fast electron injector rather than just an electron trapping center. [ 16 ] In this work, to improve the electron extraction from the perovskite absorber into the mesoporous TiO 2 , an additional lithium-neutralized graphene oxide (GO-Li) layer as electron transporting Layer (ETL) is used. GO-Li has been already used as ETL in organic photovoltaic devices by Kakavelakis et al. [ 17 ] The authors demonstrated that the replacement of H atoms in the carboxyl groups of GO by Li atoms can effectively reduce the working function (WF) of GO from 4.9 to 4.3 ± 0.1 eV. Due to low electronegativity and low WF, Li atoms lose their valence electrons to the GO plane, and the resulting positive Li + induces dipoles. This transfer of charge from the metal to the GO leads to a shift in the Fermi level toward the vacuum and a consequent decrease in WF. [ 18 ] Since the WF of GO-Li displays a good match with the Lowest Unoccupied Molecular Orbital (LUMO) level of mesoporous TiO 2 , in this work a new effi cient perovskite solar cell structure is proposed which includes the GO-Li as an interlayer between the TiO 2 and the perovskite harvester. The resulting PSCs exhibit enhanced J SC and FF and reduced Effi ciency and Stability Enhancement in Perovskite Solar Cells by Inserting Lithium-Neutralized Graphene Oxide as Electron Transporting LayerAntonio Agresti , Sara Pescetelli , Lucio Cinà , Dimitrios Konios , George Kakavelakis , Emmanuel Kymakis , and

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Reliable determination of the few‐layer graphene oxide thickness using Raman spectroscopy

Cited by 53 publications

References 48 publications

Optimising the visibility of graphene and graphene oxide on gold with multilayer heterostructures

Optimising the visibility of graphene and graphene oxide on gold with multilayer heterostructures

Electro‐mechanical properties of inkjet‐printed graphene oxide nanosheets

Efficiency and Stability Enhancement in Perovskite Solar Cells by Inserting Lithium‐Neutralized Graphene Oxide as Electron Transporting Layer

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