Moreover, the dihedral angle between the best performing hexamers is close to 180°(Table ), or in other words -flat, and is only minimally changing between the neutral and cation species (Table ). This further strengthens the hypothesis that in addition to a large π-system, better conjugation and planar chain conforma-tions contribute to the low λ. In addition to the dihedral angle, the best performing hexamers exhibit a minimal change between the neutral and the cation bond lengths.