Research Articles

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https://hdl.handle.net/20.500.14155/199

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Browsing Research Articles by Subject "Graphene"

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    Graphene: Synthesis, Transfer, and Characterization for Dye-Sensitized Solar Cells Applications
    (ACS Publications, 2013) Dodoo-Ahrin, D.; Fabiane, M.; Bello, A.
    Large area graphene films with varying growth time thicknesses were synthesized by chemical vapor deposition (CVD) on copper foil and transferred to other substrates for characterization and photovoltaic applications. Scanning tunneling microscopy, Raman spectroscopy, and imaging show films with high crystallinity, low defect density, I2D/IG ratio of 0.52?2.26, and the presence of continuous graphene sheets with optical transparency of 75.7%?96.8%. The use of CVD graphene sheets as counter electrode in dye-sensitized solar cells was explored. The short circuit current density (Jsc), the open circuit current (Voc), the fill factor (FF), and the overall conversion efficiency under AM 1.5, 100 mW cm?2 illumination are 12.7 mA/cm2 57.5% and 3.8%, respectively.
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    Growth of graphene underlayers by chemical vapor deposition
    (AIP Publishing, 2013) Fabiane, M.; Khamlich, S.; Bello, A.
    We present a simple and very convincing approach to visualizing that subsequent layers of graphene grow between the existing monolayer graphene and the copper catalyst in chemical vapor deposition (CVD). Graphene samples were grown by CVD and then transferred onto glass substrates by the bubbling method in two ways, either direct-transfer (DT) to yield poly (methyl methacrylate) (PMMA)/graphene/glass or (2) inverted transfer (IT) to yield graphene/PMMA/glass. Field emission scanning electron microscopy (FE-SEM) and atomic force microscopy (AFM) were used to reveal surface features for both the DT and IT samples. The results from FE-SEM and AFM topographic analyses of the surfaces revealed the underlayer growth of subsequent layers. The subsequent layers in the IT samples are visualized as 3D structures, where the smaller graphene layers lie above the larger layers stacked in a concentric manner. The results support the formation of the so-called �inverted wedding cake�stacking in multilayer graphene growth.