The characterization of morphology in blend thin-films of conjugated polymers and functionalized fullerenes is a critical aspect in organic photovoltaic (OPV) device research. Understanding the links between thin-film processing conditions, film nanostructure and photocurrent generation efficiency is necessary in order to develop this technology for commercial viability. Here, we review recent developments of experimental studies that probe sample nanostructure formation and modification during the processing steps commonly used in OPV device fabrication, potentially offering a deeper insight and more rational understating of these conditions.