Flexible Organic Thin‐Film Transistors with Liquid‐Crystalline Organic Semiconductor, Ph‐BTBT‐10

Flexible organic thin‐film transistors with liquid‐crystalline organic semiconductor, 2‐decyl‐7‐phenyl‐benzothienobenzothiophene (Ph‐BTBT‐10), which is suitable for flexible transistor material because the polycrystalline thin films can be easily fabricated at about 100 °C or lower by solution process, are fabricated. 25 μm‐thick polyethylene terephthalate (PET) film and photosensitive resin poly(vinyl cinnamate) (PVCi) are used as flexible substrate and gate insulator, respectively. The PVCi gate insulator layer is crosslinked by UV light and the crosslinking reaction increases solvent resistance of PVCi gate insulator. Uniform Ph‐BTBT‐10 polycrystalline thin films are fabricated on the PVCi gate insulator and the crystallinity and electrical characteristics of Ph‐BTBT‐10 are not damaged by PVCi gate insulator. The entire process is performed below 130 °C considering the heat resistance temperature of the PET film. The fabricated transistors show the mobility of and threshold voltage of 0.57 ± 0.38 V.