Electrohydrodynamic (EHD) jet printing of carbon-black composites for solution-processed organic field-effect transistors

In this study, carbon-black (CB) conducive electrodes were successfully printed using the high-resolution electrohydrodynamic (EHD) jet printing technique. The wrapping of CB bundles with a polymeric surfactant, Triton X-100 (TX-100), enabled the CB/TX-100 composites to well disperse in ethanol/deionized water for use in the preparation of conducive inks for EHD jet printing. By adjusting the voltage and operation distance, the applied electrostatic and gravity forces to the loaded CB/TX-100 inks overcame the fluid forces (viscosity and surface tension) to elongate the droplet and provide continuous jet lines, where the ink widths were smaller than the diameter of the nozzle. The EHD-printed CB/TX-100 in the stable cone-jet mode formed conducive lines and various pattern shapes. These conducive lines were utilized as source and drain electrodes of organic field-effect transistors (OFETs) with solution-processed organic semiconductors. The OFET with printed CB/TX-100 electrodes exhibited better electrical performances, including a higher saturation mobility and smaller hysteresis, than those of the reference OFET with Au electrodes.