Interface-Mediated Self-Assembly in Inkjet Printing of Single-Crystal Organic Semiconductor Films

Abstract

Recent reports have demonstrated that printing processes are more suitable for producing high-performance organic thin-film transistors (OTFTs) than vacuum processes, although the formation mechanism of solution-based films is not yet understood. Here, we use molecular dynamics simulations to show that prototypical solution-processable organic semiconductors (OSCs) form a temporal lyotropic liquid-crystalline (LLC) molecular layer at the air–liquid interface of the semiconductor solution, which subsequently serves as a versatile precursor to the growth of a single-crystalline film. The molecules exhibit spontaneous alignments of the molecular long axes to form a molecular layer that is parallel to the air–liquid interface, whereas alignment with the short axes is not observed and the molecules move diffusively within the layer. The onset of short-axis orientational and positional ordering was observed in the later stage of film growth. Our findings provide evidence that unique way of film growth occurs vi...