High-Mobility, Aligned Crystalline Domains of TIPS- Pentacene with Metastable Polymorphs Through Lateral Confinement of Crystal Growth

摘要

Solution processed organic semiconductors (OSCs) are expected to pave the way for low cost, large area, flexible, and transparent electronics. Small molecular OSCs are promising for these electronic applications, because of their high performance in organic thin film transistors (OTFTs). Recently, it has been shown that non-equilibrium molecular packing (strained lattice structure) can be realized in small molecular OSCs prepared by solution shearing, a coating method that can potentially be scaled up for large area film deposition. In the case of a model OSC, 6,13(bis-triisopropylsilylethynyl) pen-tacene (TIPS-pentacene), a packing motif with a π-π stacking distance closer than that of the equilibrium molecular packing was found. Consequently, the charge transport properties of TIPS-pentacene can be increased through the enhancement of electronic overlap between molecules. However, previous conditions where the metastable TIPS-pentacene polymorphs were obtained showed poor thin-film crystalline texture, with the presence of numerous grain boundaries and misaligned crystals, which significantly reduced charge carrier mobilities in the OTFTs.