The solid-state aggregation of π-conjugated molecules critically influences the performance of organic semiconductors, as charge transport relies on intermolecular electronic coupling, which is determined by both molecular packing and the phase and nodal properties of frontier π-orbitals. This presentation covers two strategies for engineering such aggregates in organic semiconductors.

The first strategy is molecular orbital engineering through a molecular substitution approach, enabling control over frontier orbital arrangement without altering molecular shape or crystal packing. Using N,N’-diethynylated derivatives of 6,13-dihydro-6,13-diazapentacene, we have demonstrated this strategy achieving field effect mobilities more than twice of those of their parent pentacene derivatives in organic field effect transistors (OFETs).

The second strategy is to use curved π-molecules to access unconventional packing motifs inaccessible to planar frameworks. We highlight the unique π-stacking of a double helicene, which allows diverse functional groups to be introduced without disrupting π–π interactions, enabling high-performance chemical and biological sensors based on OFETs.