Graphoepitaxy-Directed Assembly of Organic Semiconductor Single Crystals into Trellis Structures

In the field of organic electronics, organizing crystals into structures that promote efficient optoelectronic processes during rapid solution processing remains an outstanding challenge. Here, nanopillar grids are employed to direct the crystallization of organic semiconductor perylene during continuous solution-phase dip coating. These platelike crystals are found to orient in two distinct out-of-plane orientations with the large-area faces either parallel or perpendicular to the substrate surface. Perpendicular crystals are further found to adopt the underlying grid ordering, with crystals preferentially growing between the rows and columns of nanopillars to form structures resembling trellises. This observation of graphoepitaxy is a consequence of registry between the periodicity of the nanopillar grid and the growth habit of perylene, resulting in three-dimensional structures with ordering spanning the molecular to micrometer length scale. The ability to direct crystals into hierarchical structures with optimized orientations, surface areas, and sizes will have broad implications across materials disciplines.