Driving organic field-effect transistors: enhancing crystallization and electrical performance with blends and inkjet printing

The drive to deliver ever-more powerful and feature-rich organic integrated circuits has made the interface contact quality improvement—that is, the process of alleviating the hysteresis phenomenon and contact resistance of the electrical properties in organic field-effect transistors (OFETs)—a critical challenge for the organic semiconductor (OSC) microelectronics industry. The use of blends of OSCs and insulating binding polymers has offered a breakthrough to circumvent these limitations. Here, we introduced a novel method for preparing high-performance OFETs based on a direct-writing inkjet printing (DWIP) blend composed of 6,13-bis(triisopropylsilylethinyl) pentacene (TIPS-pentacene) and poly(methyl methacrylate) (PMMA). The small molecular weight of PMMA imparted significantly superior crystallization of small-molecule OSCs, and the OFETs exhibited better electrical performance than other comparative conditions. The crystallization and characteristics improved because of two mechanisms: First, the PMMA delivered superior mechanical strength, stability, and improved film uniformity and created a more uniform interface that decreased the charge accumulation, thereby alleviating the hysteresis and contact resistance. Second, combined with DWIP technology and thanks to the advantages of horizontal solution shearing and spatially restricted domains, the blends contributed to solute draw and thus handled mass transport more efficiently and controllably. The proposed method provides attractive properties for industrial applications.