Adv. Mater. http://doi.org/f3gkw8 (2015)

Credit: WILEY

Semiconductor small molecules aligned into defect-free single crystals have shown improved optoelectronic performance. Several approaches have been developed to control molecular assembly on large areas, yet fast fabrication of arrays of single crystals with customized geometry, a key step for the use of organic semiconductors in large-scale integrated circuits, is still challenging. Wei Deng and colleagues now show that spin-coating of fast-evaporating solutions of 9,10-bis(phenylethynyl)anthracene and other molecules on pre-patterned wafers is an effective way to realize arrays of crystalline organic nanowires within one minute. The deposited solution fills the gaps between the photoresist patterns realized on the substrate and then rapidly exits due to both evaporation and centrifugal force. However, it remains partially pinned at the edges of the patterns, where the molecules nucleate and self-assemble into crystalline nanowires. This method is used to realize complex patterns of organic crystals with arbitrary shapes, as well as parallel nanowire arrays working as high-mobility conducting channels in flexible organic field-effect transistors.