Tuning Organic Semiconductor Alignment and Aggregation via Nanoconfinement

The nanoconfinement of organic semiconductors in nanoporous media presents a means of manipulating molecular assembly and optoelectronic properties. This work introduces a solution-infiltration process with slow solvent evaporation for filling nanoporous anodic aluminum oxide templates with crystalline organic semiconductors. This approach is used to systematically study the dependence of crystal growth on nanopore size for four organic semiconductors, including planar small molecules, a fullerene, and a polymer. The planar molecules exhibit preferential π–π stacking along the pore axis in addition to a second co-existing growth orientation, indicating competition between fast-growth directions as nuclei attempt to reach a critical cluster size. Size-dependent effects were seen in the crystallinity, crystal orientation, and molecular aggregation of these compounds.