One-volt, solution-processed organic transistors with self-assembled monolayer-Ta₂O₅ gate dielectrics

Low-voltage, solution-processed organic thin-film transistors (OTFTs) have tremendous potential to be key components in low-cost, flexible and large-area electronics. However, for these devices to operate at low voltage, robust and high capacitance gate dielectrics are urgently needed. Herein, the fabrication of OTFTs that operate at 1 V is reported. These devices comprise a solution-processed, self-assembled monolayer (SAM) modified tantalum pentoxide (Ta₂O₅) as the gate dielectric. The morphology and dielectric properties of the anodized Ta₂O₅ films with and without n-octadecyltrichlorosilane (OTS) SAM treatment have been studied. The thickness of the Ta₂O₅ film was optimized by varying the anodization voltage. The results show that organic TFTs gated with OTS-modified tantalum pentoxide anodized at 3 V (d ~7 nm) exhibit the best performance. The devices operate at 1 V with a saturation field-effect mobility larger than 0.2 cm² V^-1 s^-1, threshold voltage -0.55 V, subthreshold swing 120 mV/dec, and current on/off ratio in excess of 5 × 10³. As a result, the demonstrated OTFTs display a promising performance for applications in low-voltage, portable electronics.