High Operation Frequency and Strain Tolerance of Fully Printed Oxide Thin Film Transistors and Circuits on PET Substrates.

The major limitations of solution-processed oxide electronics include high process temperatures and the absence of necessary strain tolerance that would be essential for flexible electronic applications. Here, a combination of low temperature (<100 °C) curable indium oxide nanoparticle ink and a conductive silver nanoink, which are used to fabricate fully-printed narrow-channel thin film transistors (TFTs) on polyethylene terephthalate (PET) substrates, is proposed. The metal ink is printed onto the In 2 O 3 nanoparticulate channel to narrow the effective channel lengths down to the thickness of the In 2 O 3 layer and thereby obtain near-vertical transport across the semiconductor layer. The TFTs thus prepared show On/Off ratio ≈10 6 and simultaneous maximum current density of 172 µA µm -1 . Next, the depletion-load inverters fabricated on PET substrates demonstrate signal gain >200 and operation frequency >300 kHz at low operation voltage of V DD = 2 V. In addition, the near-vertical transport across the semiconductor layer is found to be largely strain tolerant with insignificant change in the TFT and inverter performance observed under bending fatigue tests performed down to a bending radius of 1.5 mm, which translates to a strain value of 5%. The devices are also found to be robust against atmospheric exposure when remeasured after a month.