We found an abrupt reduction of contact resistance, Rc, in pentacene bottom-contact thin-film transistors (TFTs) with Au/Ti source/drain (S/D) electrodes when Ti thickness is below ∼3nm. Our results suggest that the direct ohmic contact with a few molecular layer channel is a key to reduce the Rc of the S/D electrodes. We propose a Au/self-assembled monolayer electrode structure enabling direct ohmic contact with these few molecular layer channels, and achieved high-performance bottom-contact TFTs with an extrinsic mobility of 1.1cm2∕Vs, an on/off ratio of 106, and a subthreshold swing of 0.3 V/decade.

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A high‐performance pentacene organic‐TFT backplane with a solution‐processed novel poly(4‐vinylphenol)‐based dielectric and a solution‐processed organo‐silver electrode/wire has been developed below 150°C. The all‐organic‐TFT backplane has been successfully applied to drive a QQVGA active‐matrix (AM) polymer‐dispersed (PD) LCD with a resolution of 79 dpi and a display size of 2.5 inches.

We identified two causes of source/drain (S/D) series resistance (Rs) in bottom-contact (BC) pentancene thin-film transistors (TFTs). One is mixed-phase pentacene grown in the blurred- edge region of Au electrodes and the other is the semi-insulating pentacene region between the Au electrode and the carrier-accumulating layer. A novel Au S/D electrode structure with a self-assembled monolayer (SAM) adhesion layer enables direct injection of carriers into the accumulating layer and markedly reduces Rs for unit gate width (RsW) to 6 Mωμ[.proportional]m. BC TFTs with this electrode structure showed extrinsic field-effect mobility as high as 1.1 cm2/Vs.

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