Mapping the Crystalline Phase Space of a Molecular Semiconductor to Understand Effects on Charge Transport
Small molecules – be they pharmaceuticals, explosives, dyes, flavors for food, or, as the Loo Group studies, molecular semiconductors – can adopt a variety of crystal structures, a phenomenon known as polymorphism. Because these materials’ properties can vary significantly with changes in crystal structures, polymorph discovery is a topic of general importance across materials chemistry yet also challenging as it is difficult to predict the necessary conditions to access alternative crystal structures. Graduate student Anna Hiszpanski and her collaborators observed three polymorphs of the organic semiconductor pictured above, contorted hexabenzocoronene (cHBC), two of which had not been previously reported. Using simple processing techniques, they mapped the processing pathways by which one polymorph may convert to another, and, utilizing these techniques, quantified the effect that changes in cHBC’s crystal structure have on charge transport in electronic devices incorporating cHBC.
Read the full story at http://pubs.acs.org/doi/abs/10.1021/ja5091035