Carbohelicenes have two main non-covalent interactions between the molecules: C-H-π, and π -π interactions. As favourable charge-transport properties often rely on having a high degree of π -π stacking, our main interest lies in how the degree of π -π stacking changes with helicene length. In order to determine how helicene length might effect chargetransport properties, we evaluated the propensity for π -π stacking interactions for each helicene length by measuring the degree of π -π stacking in the polymorphs, quantified by the percentage of aromatic rings of the helicene backbone involved in a π -π interaction (Fig. ).