Controlling crystallization to improve charge mobilities in transistors based on 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene

Long-range order at multiple length scales in small molecule semiconductors is critical to achieve effective electrical charge transport. As a consequence, processing strategies are often important for the fabrication of high-performance devices, such as thin-film transistors. We demonstrate that melting followed by quenching at a fixed temperature can obviate prior processing, control the crystallization process, and lead to enhanced charge mobilities in thin-film transistors based on 2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene active layers. Melting followed by quenching to 80 °C yields films with higher degrees of orientational order, and therefore charge mobilities in devices that are higher by a factor of five over films annealed at the same temperature directly after film casting.