High-performance organic field-effect. transistors (OFETs) based on polyelectrolyte gate dielectric and electrospun poly(3-hexylthiophene) (P3HT) nanofibers were fabricated oil a flexible polymer substrate. The use of UV-crosslinked hydrogel including ionic liquids for the insulating layer enabled fast and large-area fabrication of transistor arrays. The P3HT nanofibers were directly deposited on the methacrylated polymer substrate. During UV irradiation through a patterned mask, the methacrylate groups formed covalent bonds with the patterned polyelectrolyte dielectric layer, which provides mechanical stability to the devices. The OFETs operate at voltages of less than 2 V. The average field-effect mobility and on/off ratio were similar to 2 cm(2)/(Vs) and 10(5), respectively.