Electrohydrodynamic jet printing of small-molecule semiconductor crystals on chemically patterned surface for high-performance organic field-effect transistors

Abstract

Direct writing of organic semiconducting crystals by electrohydrodynamic jet (EHD) printing has enabled the low-cost large-area fabrication of organic semiconducting crystal arrays without the need of complicated patterning procedures. However, morphological variations within a single printed pattern (e.g., variations in thickness, crystallinity, and local crystal orientation) caused by the "coffee-ring effect" can be an issue during their application in organic field-effect transistors (OFETs) since their charge-transport properties significantly affect the device characteristics. Herein, we report the EHD printing of small-molecule semiconducting crystals on a chemically patterned substrate to suppress the "coffee-ring effect" and produce uniform high-quality crystals oriented along the printing direction. The EHD printing of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPSPEN) on hydrophobic polyurethane acrylate line patterns on a dielectric surface enables the selective and guided growth of the crystals. The OFETs with the TIPS-PEN crystals printed on the patterned surface exhibit an average field-effect mobility of 0.34 cm2/(V s), which is more than twice of that of the OFETs fabricated with crystals