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Here, we report on high-performance top-gated poly(3,3″′-dialkyl-quarterthiophene) (PQT-12) organic thin-film transistors (OTFTs) with reverse-offset-printed (ROP) silver (Ag) source/drain (S/D) electrodes. OTFT devices with ROP S/D electrodes using Ag nanopaste show higher performance (∼0.01 cm2/Vs) than those fabricated by vacuum electron beam evaporation with conventional photolithography and a standard lift-off process (∼1 × 10−3 cm2/Vs). This dissimilarity is attributed to the higher work function (−4.9 eV) of the ROP Ag electrode due to AgO formation on the Ag surface during thermal annealing. This results in a low interfacial hole injection energy barrier between the S/D electrodes and the PQT-12 semiconductor.

This study examined the interfacial reaction of plasma-enhanced atomic layer deposited TaCxNy films with underlying SiO2 and HfO2 layers, as well as their effective work functions (EWFs). The adoption of Ar∕H2 plasma as a reducing agent suppressed the interfacial reactions resulting in a lower electrical thickness. However, it increased the interface state density due to the massive Ar+ plasma damage on the dielectric films. The interfacial reactions were suppressed in TaCxNy on HfO2 compared with that on SiO2. The EWF of TaCxNy with the H2 plasma and Ar∕H2 plasma on HfO2 was ∼4.9–5.2 and ∼4.6eV, respectively.

We investigated preferentially oriented pentacene grains on rubbed polyimide (PI) layers under various conditions, such as substrate temperature and cumulative rubbing number. In case of pentacene thin films deposited on rubbed PI at room temperature (RT), compared to unrubbed, the field-effect mobilities were improved by two- to threefold in contrast to the cases of elevated temperature. From the results of crystalline in-plane orientation and thin-film versus bulk-phase ratio, we proposed that pentacence crystalline orientation on a rubbed PI layer could be more favorable at RT, whereas the heating energy might weaken the interaction energy between pentacene molecules and aligned PI layer.

A thermally cross-linkable perfluorocyclobutane (PFCB) polymer was synthesized and examined for use as the gate dielectric in organic thin film transistors (OTFTs). The PFCB polymer showed good solvent and process resistance during the photolithographic patterning of the electrodes. Bottom contact OTFTs were fabricated with poly(3-hexylthiophene)-2,5-diyl (P3HT) as the semiconductor, either spin cast or dip coated, on the PFCB gate dielectric. OTFTs fabricated with dip-coated P3HT showed a field effect mobility of 1.8×10−3cm2∕Vs and a high on/off current ratio of 8.3×106 in the saturation regime, with a source-drain voltage of VD=−50V.