Fabrication of large-area organic semiconducting crystalline thin films with controlled morphology by antisolvent-assisted dip coating

Abstract

The solution-based coating of organic semiconductors offers significant potential for the low-cost manufacturing of large-area, flexible electronic devices. However, the rapid and complex fluid dynamics associated with solution coating present challenges in controlling thin-film morphology. In this study, we demonstrate a simple antisolvent-assisted dip coating approach to fabricate ultrathin, uniform films of Dioctylbenzothienobenzothiophene ([Formula: see text]-BTBT) with centimeter-scale coverage. The film morphologies can be tuned from large-area, well-aligned crystalline domains to highly uniform thin films by adjusting the dip-coating speeds and the solvent-to-antisolvent ratio. The introduction of an antisolvent into the solution creates a surface tension gradient, inducing Marangoni flow. This fluid dynamic process promotes the aggregation of [Formula: see text]-BTBT molecules at the solvent/antisolvent interface, enhancing film morphologies over a centimeter scale. The organic field-effect transistors (OFETs) fabricated from these [Formula: see text]-BTBT crystalline films exhibit superior electrical performance, with average and maximum carrier mobilities of 4.8 [Formula: see text] and 6.8 [Formula: see text], respectively. Therefore, this method offers a cost-effective and convenient deposition approach for more complex applications, such as large-area organic integrated circuits.