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A theoretical investigation of the molecular organization at a sexithiophene (T6)-C60 fullerene planar heterojunction, based on atomistic molecular dynamics, is presented, in which the effect of two different sample preparation processes on the resulting interface morphology is explored. First, the landing of T6 on C60(001) substrate is considered, which leads to crystalline layers of standing and tilted molecules, in accordance with experiments. The observation and the quantitative characterization of the nucleation and growth provide detailed insights on this out-of-equilibrium process, including the establishment of an epitaxial relationship between the substrate and the interfacial T6 layer, and the spontaneous formation of defective islands, characterized by chiral edges, during the growth of the second and third layers. It is then shown that molecular orientations can be radically changed upon annealing at 600 K, at which T6 forms a smectic phase with planar alignment, whose layers are perpendicular to the interface. The interfacial T6 morphologies are then analyzed in detail at room temperature and compared to the known bulk polymorphs. [ABSTRACT FROM AUTHOR]

It is reported that terahertz radiation from 0.69 to 2.54 THz has been sensitively detected in a device consisting of bundles of carbon nanotubes containing single wall metallic carbon nanotubes, quasioptically coupled through a lithographically fabricated antenna, and a silicon lens. The measured data are consistent with a bolometric detection process in the metallic tubes and the devices show promise for operation well above 4.2 K. [ABSTRACT FROM AUTHOR]

A theoretical investigation of the molecular organization at a sexithiophene (T6)-C60 fullerene planar heterojunction, based on atomistic molecular dynamics, is presented, in which the effect of two different sample preparation processes on the resulting interface morphology is explored. First, the landing of T6 on C60(001) substrate is considered, which leads to crystalline layers of standing and tilted molecules, in accordance with experiments. The observation and the quantitative characterization of the nucleation and growth provide detailed insights on this out-of-equilibrium process, including the establishment of an epitaxial relationship between the substrate and the interfacial T6 layer, and the spontaneous formation of defective islands, characterized by chiral edges, during the growth of the second and third layers. It is then shown that molecular orientations can be radically changed upon annealing at 600 K, at which T6 forms a smectic phase with planar alignment, whose layers are perpendicular to the interface. The interfacial T6 morphologies are then analyzed in detail at room temperature and compared to the known bulk polymorphs. [ABSTRACT FROM AUTHOR]

Abstract: We present a Monte Carlo simulation study of the phase behaviour and molecular organization of a system of fullerene-based mesogens, represented by a three-site model composed of a fullerene sphere and two mesogenic moieties rigidly attached to it. It is shown that a combination of suitably modified Lennard-Jones and Gay–Berne attractive–repulsive potentials allows a satisfactory qualitative modeling of the interactions between the fullerene derivatives under investigation. Indeed, simulation results show that, despite the crude representation of the molecular structure, our model generates nematic and smectic phases, thus accounting qualitatively for the basic experimental observations on the class of compounds considered. [Copyright &y& Elsevier]