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We consider the effects of dephasing on field-induced coherent charge and energy transport in molecular junctions. Within generic models we show that dephasing controls the relative intensities of energy and charge fluxes, and that the dependence of the energy flux on the dephasing rate is nonmonotonic. We further demonstrate the possibility for laser-controlled charge-energy separation in multiterminal molecular junctions, a prerequisite for engineering low-heating stable nanoscale devices. [ABSTRACT FROM AUTHOR]

The possibility of using single-molecule junctions as electron pumps for energy conversion and storage is considered. It is argued that the small dimensions of these systems allow the use of unique intramolecular quantum coherences in order to pump electrons between two leads and to overcome relaxation processes which tend to suppress the pumping efficiency. In particular, we demonstrate that a selective transient excitation of one chromophore in a bichromophoric donor-bridge-acceptor molecular junction model yields currents which transfer charge (electrons and holes) unevenly to the two leads in the absence of a bias potential. The utility of this mechanism for charge pumping in steady-state conditions is proposed. [ABSTRACT FROM AUTHOR]