Non-lithographic direct patterning of carbon nanomaterial electrodes via electrohydrodynamic-printed wettability patterns by polymer brush for fabrication of organic field-effect transistor

In this study, we report a new approach for patterning of carbon nanomaterials via the solution route through wettability patterning using electrohydrodynamic (EHD) printing. Differences in wettability were successfully obtained by treating dimethylchlorosilane-terminated polystyrene (PS-brush) with the micro-dripping mode of EHD printing up to 6-μm line width and scaled fine patterns with various shapes at 6-μm printing conditions. We obtained sub-micrometer scaled carbon nanomaterial patterns, which were utilized as source and drain (S/D) electrodes for organic field-effect transistors (OFETs), without using any lithographic process. In addition, the PS-brush treatment modified the surface hydrophobicity of the substrates that served as the PS-brush and SiO₂ bilayer dielectrics to guarantee high stability during the OFET operation. As a result, the OFETs employing S/D electrodes based on carbon nanomaterial patterns exhibited the electrical performance of typical p-type OFETs with negligible hysteresis. Additionally, we confirmed that a solution processing organic semiconductor forms a more suitable crystal structure than a vacuum process based organic semiconductor by several tools like CPOM, AFM, and 2D-GIXD.