Facile photo-patterning of source and drain electrodes with photo-sensitive polyimide for organic thin-film transistors

We report a facile and cost-effective photo-patterning process to obtain patterned source and drain electrodes in organic thin-film transistors (OTFTs). Instead of conventional photoresist, photo-sensitive polyimide (PSPI) was used in the photo-patterning process. PSPI with cinnamate moieties could be crosslinked by UV-light exposure without any photoinitiator. After the photo-patterning process of this work, gold/PSPI bilayer electrodes were easily prepared and they were used as source and drain electrodes of the pentacene OTFT. The field effect carrier mobility, threshold voltage and on/off current ratio of the pentacene OTFT with the gold/PSPI bilayer electrodes were 0.067 cm2/V s, −5.3 V and 1.4 × 104, respectively.