  In this paper, an optoelectronic device simulation framework valid for
arbitrary spatial variation of electronic potentials and optical modes, and for
transport regimes ranging from ballistic to diffusive, is used to study
non-local photon absorption, photocurrent generation and carrier extraction in
ultra-thin film and nanostructure-based solar cell devices at the radiative
limit. Among the effects that are revealed by the microscopic approach and
which are inaccessible to macroscopic models is the impact of structure, doping
or bias induced nanoscale potential variations on the local photogeneration
rate and the photocarrier transport regime.
