Microcavity effects on the generation, fluorescence, and diffusion of excitons in organic solar cells

We compute the short-circuit diffusion current of excitons in an organic solar cell, with special emphasis on fluorescence losses. The exciton diffusion length is not uniform but varies with its position within the device, even with moderate fluorescence quantum efficiency. With large quantum efficiencies, the rate of fluorescence can be strongly reduced with proper choices of the geometrical and dielectric parameters. Hence, through proper micro-cavity design, the diffusion length can be increased and the device performance significantly improved without recourse to triplet excitonic states.