In this work, we present our results on the influence of post-deposition treatments on the morphology and optical properties of photoactive films made of small molecules and their subsequent effect on the performance of photovoltaic (PV) devices. We have chosen DPP(TBFu)2:PC61BM as a benchmark model system and compared a novel joule-heating annealing (JHA) treatment with the widely used temperature annealing (TA) and solvent annealing (SVA) treatments. Detailed characterization of the morphology of the active layer and the performance of the devices suggests that JHA is a valuable post-treatment technique that provides fast information about the development of domains in the photoactive layer. Finally, in this context, solar cells on flexible indium tin oxide (ITO) substrates, made of polyethylene terephthalate (PET), were fabricated and analyzed.
