Organic nanograting heterojunctions for photoelectric conversion were studied based on a two-dimensional analytic exciton transport model. The photocurrent and external quantum efficiency were investigated as the function of materials and geometric parameters. It showed that the introduction of the complicated heterointerfaces changed the exciton distribution within the nanostructures and enhanced significantly the exciton dissociation probability. The photoelectric conversion was determined by the cooperation of the two mechanisms of light absorption and exciton migration. The possibility of the nanograting heterojunctions applied to photovoltaic devices was evaluated quantitatively with the recombination-dominated assumption at donor-acceptor interface. The results suggested that the photovoltaic performance in these nanograting heterojunctions might be improved significantly after optimization when compared to that in a planar heterojunction. (c) 2007 Elsevier B.V. All rights reserved.