Photo-crosslinkable and low-temperature processable polyimide gate insulator for pentacene thin-film transistors

Abstract

We have prepared a photo-crosslinkable, low-temperature processable, and soluble polyimide (SPI-Cinnamoyl: SPI-CM) gate insulator. Firstly, the soluble polyimide with hydroxyl group (SPI-Hydroxyl: SPI-OH) was synthesized through one-step condensation polymerization of monomers, 5-(2,5-dioxytetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride (DOCDA) and 3,3’-dihydroxy-4,4’-diaminobiphenyl (HAB). And, then SPI-OH was further reacted with cinnamoyl chloride to make a photo-crosslinkable polyimide (SPI-CM). The thin film of photo-crosslinked SPI-CM (C-SPI-CM) exhibited a dielectric constant as 3.7 at 10 kHz, and leakage current density of <9.7 × 10−11 A/cm2. In addition, SPI-CM could be easily patterned by selective UV-light exposure. A pentacene thin-film transistor (TFT) with the photo-crosslinked SPI-CM as a gate dielectric showed a field effect mobility of 0.16 cm2/Vs.