Abstract
Printing is an emerging approach for low-cost, large-area manufacturing of electronic circuits, but it has the disadvantages of poor resolution, large overlap capacitances, and film thickness limitations, resulting in slow circuit speeds and high operating voltages. Here, we demonstrate a self-aligned printing approach that allows downscaling of printed organic thin-film transistors to channel lengths of 100–400 nm. The use of a crosslinkable polymer gate dielectric with 30–50 nm thickness ensures that basic scaling requirements are fulfilled and that operating voltages are below 5 V. The device architecture minimizes contact resistance effects, enabling clean scaling of transistor current with channel length. A self-aligned gate configuration minimizes parasitic overlap capacitance to values as low as 0.2–0.6 pF mm−1, and allows transition frequencies of fT = 1.6 MHz to be reached. Our self-aligned process provides a way to improve the performance of printed organic transistor circuits by downscaling, while remaining compatible with the requirements of large-area, flexible electronics manufacturing.
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Acknowledgements
The research was supported by the Engineering and Physical Sciences Research Council (EPSRC) and the EU Integrated Project NAIMO (No NMP4-CT-2004-500355). The authors thank the Dow Chemical Company and Merck for providing F8T2 and pBTTT, D.J. Stokes (FEI Company) for FIB-SEM measurement, A. Facchetti (Northwestern University) for helpful discussions, R. Peterson (Cavendish Laboratory) for inverter measurements, X. Cheng (Cavendish Laboratory) for helpful support, and M. Tello (Cavendish Laboratory) for performing the Kelvin probe work function measurements.
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Y.Y.N. and H.S. conceived and designed the experiments. Y.Y.N. performed the experiments. N.Z. contributed to self-aligned inkjet printing. M.C. measured the transition frequency of transistors. Y.Y.N. and H.S. analysed the data and co-wrote the paper.
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H.S. and Y.Y.N. have filed a patent application on the process described in this work.
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Noh, YY., Zhao, N., Caironi, M. et al. Downscaling of self-aligned, all-printed polymer thin-film transistors. Nature Nanotech 2, 784–789 (2007). https://doi.org/10.1038/nnano.2007.365
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DOI: https://doi.org/10.1038/nnano.2007.365
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