  We theoretically investigate the effect of inter-molecular Coulomb
interactions on transport through molecular monolayers (or other devices based
on a large number of nanoscale conductors connected in parallel). Due to the
interactions, the current through different molecules become correlated,
resulting in distinct features in the non-linear current-voltage
characteristics, as we show by deriving and solving a type of modified master
equation, suitable for describing transport through an infinite number of
interacting conductors. Furthermore, if some of the molecules fail to bond to
both electrodes, charge traps can be induced at high voltages and block
transport through neighboring molecules, resulting in negative differential
resistance.
