Publications (4)3.84 Total impact
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Article: Photocurrent generation in random networks of multiwall-carbon-nanotubes grown by an “all-laser” process
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ABSTRACT: We report photocurrent generation in entangled networks of multiwall-carbon nanotubes (MWCNTs) grown on TiN/Si substrates by an all-laser process. By integrating these MWCNTs into planar devices, we demonstrate that they generate photocurrent over all the visible and near-ultraviolet range, with maximum efficiency around 420 nm. Photocurrent is obtained even at zero applied voltage, pointing to a true photovoltaic (PV) effect. The extracted photocurrent as a function of applied voltage exhibits nonlinear behavior for voltages ≥ 2 V, suggesting that the devices do not behave as pure photoresistances. Other mechanisms (e.g., Schottky barriers imbalance) are invoked to describe current flow in these PV devices.Applied Physics Letters 08/2009; 95(8):083114-083114-3. · 3.84 Impact Factor -
Article: Multiwall Carbon Nanotubes Decorated with Copper Nanoparticles: Effect on the Photocurrent Response
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ABSTRACT: Photocurrent generation measured with an electrochemical cell on carbon nanotubes has been obtained mainly from single-walled nanostructures. In fact, multiwall carbon nanotubes (MWCNTs) were not expected to show analogous low-dimensional effects, due to their close similarity to metallic graphite. Recently we reported on the ability of MWCNTs to generate photocurrent in the visible and ultraviolet spectral range. In this paper we show a significant enhancement in the photocurrent generation when the walls of the MWCNTs were decorated with dispersed Cu nanoparticles. This result is of particular relevance for photovoltaic nanodevices and solar energy conversion applications.J. Phys. Chem. C. 04/2009; 113:5860-5864. -
Article: Comparison of the local order in highly oriented pyrolitic graphite and bundles of single-wall carbon nanotubes by nanoscale extended energy loss spectra
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ABSTRACT: We compare the local order in single-wall carbon nanotubes (SWCNTs) and highly oriented pyrolitic graphite (HOPG) by means of nanoscale transmission extended energy loss fine structure (EXELFS) measurements above the carbon K edge. The HOPG EXELFS spectra and their Fourier transform were compared to their synchrotron extended X-ray absorption fine structure (EXAFS) counterpart and discussed within a multiple scattering framework. By comparing the experimental EXELFS data to spectra calculated using a theoretical model based on a single scattering approach, we showed the fundamental importance of considering multiple paths (involving up to eight body scattering) to reproduce the fine details of EXELFS features. Simulating EXELFS spectra of SWCNTs by our theoretical model is shown to represent a measure of their chiralities. Finally, the shrinkage of the nearest-neighbor distance in the Fourier transform observed for SWCNTs (absent in graphite) is interpreted within a simple model invoking anharmonic effects.J. Phys. Chem. C. 03/2009; 113:4848-4855. -
Article: Photon harvesting with multi wall carbon nanotubes
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ABSTRACT: In this work we show that a sizeable enhancement in the photocurrent over the visible and near ultraviolet energy range can be obtained from multi-wall carbon nanotubes when decorated with Cu-nanoparticles. The result has been obtained both from electrochemical and solid state cells measurements. The photoactive metal nanoparticles do not change the intrinsic ability of multi-wall carbon nanotubes to behave as an efficient low dimensional media for generating e–h carriers. This result further confirms that multi wall carbon nanotubes can be used in photovoltaic nano-devices and solar energy conversion applications.Superlattices and Microstructures.
