Predicting the morphology of semiconducting polymers used in organic photovoltaics is difficult because of their long relaxation times. Coarse-grained models permit access to the time-scales required to observe equilibration, but can introduce structural artifacts. Here we present and compare the computational costs and structural differences of three models of benzodithiophene and cyclopenta[c] thiophene-4,6,-dione based copolymers, including the degree to which they reproduce pi-stacked and lamellar structural features observed in experiments. We find that the use of rigid bodies to represent the aromatic groups of each copolymer subunit can decrease computational cost by a factor of two without introducing packing artifacts that arise from the representation of planar groups with spherical simulation beads.
