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Flexible low‐voltage organic thin‐film transistors (TFTs) with Ag source/drain contacts are fabricated, and the contact resistance is measured using the transfer length method. The TFTs are fabricated in the inverted coplanar (bottom‐gate, bottom‐contact) device architecture, using the vacuum‐deposited small‐molecule semiconductor dinaphtho[2,3′b:2′,3′‐f]thieno[3,2‐b]thiophene (DNTT). Prior to the semiconductor deposition, the contact surface is functionalized with a chemisorbed monolayer of pentafluorobenzenethiol (PFBT). For comparison, TFTs with PFBT‐functionalized Au source/drain contacts are fabricated on the same substrate. Overall, the performance of the TFTs with the Ag contacts is very similar to that of the TFTs with the Au contacts, and the contact resistance of the TFTs with the Ag contacts (377 Ωcm) is the smallest reported to date for p‐channel organic TFTs with a contact material other than Au or Pt. [ABSTRACT FROM AUTHOR]

Organic thin‐film transistors (TFTs) that provide subthreshold swings near the theoretical limit together with large on/off current ratios at very low operating voltages require high‐capacitance gate dielectrics with a vanishingly small defect density. A promising approach to the fabrication of such dielectrics at temperatures sufficiently low to allow TFT fabrication on polymeric substrates are hybrid dielectrics consisting of a thin metal oxide layer in combination with a molecular self‐assembled monolayer (SAM). Here, the electrical and surface properties of titanium oxide produced by the plasma‐assisted oxidation of the surface of vacuum‐deposited titanium gate electrodes and its use as the first component of a hybrid TiOx/SAM gate dielectric in flexible organic TFTs are investigated. These transistors have a gate‐dielectric capacitance of about 1 µF cm−2, a subthreshold swing of 59 mV decade−1 (within measurement error of the physical limit at room temperature) for a wide range of channel lengths as small as 0.7 µm, and an on/off current ratio of 107 for a gate‐source‐voltage range of 1 V. [ABSTRACT FROM AUTHOR]