The morphology of blends of conjugated polymers (electron donors) and fullerene derivative molecules (electron acceptors) strongly affects the efficiency of organic solar cells. Recently, minority component solvent additives such as diiodooctane (DIO) and chloronapthalene (CN) have been used in these blends to alter blend morphology and to significantly improve device efficiency. In this work we present coarse-grained molecular dynamics simulations of conjugated polymer and fullerene derivative blends with additives of varying length, chemical functionalization, and volume fraction to understand how these additives affect morphology and to elucidate what physical and chemical features of solvent additives are important for tuning morphology. We find that the combination of additive length and the number of additive functional groups tunes the extent of blend phase separation and of intercalation of acceptor molecules between donor polymer side chains.

Understanding the effects of physical and chemical features of solvent additives on the bulk heterojunction morphology of blends of conjugated polymers and fullerene derivatives using molecular simulations

249th National Meeting (2015)

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