Fully gravure and ink-jet printed high speed pBTTT organic thin film transistors

Organic thin film transistors with channel lengths below 20 μm have been fabricated on plastic substrates using a combination of rotogravure and ink-jet printing exclusively. Gravure is utilized to deposit thin, smooth, and narrow metal lines ideal for gate electrodes; a poly(4-vinylphenol) dielectric; and a poly(2,5-bis(3-tetradecylthiophene-2-yl)thieno[3,2-b]thiophene) (pBTTT) semiconductor using a heated roll. A novel fluid guiding technique is used to maintain closely spaced ink-jet printed source and drain (S/D) contacts. Together these printing processes yield aggressively scaled yet easily manufacturable TFTs with operating frequencies of 18 kHz.