LAUSR

Abstract After light absorption in organic photovoltaic cells, the processes of exciton generation, charge separation, and charge transport depend on the phase-separated structure of films composed of two or more organic semiconductors. The phase-separated structure is thought to be composed of aggregates approximately 20 nm in size; however, these structures remain poorly characterized. We have found a method to control the formation of the phase-separated structure with the use of fullerene derivatives having different solubilities. We clarified details of the structure using solvent extraction of fullerene derivatives from the blended film together with atomic force microscopy analysis. Our results confirm that the nature of the phase separation structures contributes to charge separation and subsequent carrier transport in organic photovoltaic cells.