The role of molecular attributes on crystallization and self-nucleation of conjugated polymers*

Mechanical, optical, and diffusive properties of classical semicrystalline polymers are dictated by morphology, which in turn is highly dependent on crystallization conditions and chain molecular characteristics. In the case of conjugated polymers, even small differences in morphology—i.e. crystallinity, orientation, or amount of tie chains between crystallites—can significantly impact transport properties; however, the exact interplay between polymer chain structure, crystallization conditions, and morphology development remains obscured, partly because common solvent processes such as spin coating typically result in ill-defined crystallization conditions. Here, we investigate the role of molecular characteristics on solventless crystallization of poly-3-hexylthiophene under well-defined conditions. The results show that molecular characteristics play a key role in the way crystallization proceeds, and that self-nucleation strategies are effective at manipulating crystallization and morphology but are also highly dependent on molecular characteristics.