Self‐Aligned Megahertz Organic Transistors Solution‐Processed on Plastic

Abstract

The processing of complex nanoscale electronic structures on plastic substrates is a significant challenge, requiring the combination of low temperature, nonaggressive, and high resolution methods. Here a scalable process flow on plastic is presented tbat enables the fabrication of flexible nano­imprinted organic field‐effect transistors (OFETs) with self‐aligned contacts and solution‐processed semiconductor and dielectric layers, at processing temperatures ≤ 150 °C. OFETs are fabricated with device cutoff frequencies f > 1 MHz at low operating bias V DS = −15 V. The technique allows the patterning of metal structures over four orders of magnitude from 375 nm to 1 mm without the need for a rigid carrier, and provides a fabrication pathway to high performance nanostructured organic circuitry.

Self-aligned organic field-effect transistors on plastic with picofarad overlap capacitances and megahertz operating frequencies

“…We have previously reported on how ultraviolet nanoimprint lithography (UV-NIL) can be used to pattern sub-micron channel length devices on plastic substrates. 6 Smaller channel lengths reduce the transit time for carriers and hence increase the switching frequency. 7,8 We utilise a self-aligned process, whereby the patterned gate defines the spacing of the source-drain electrodes.…”

“…21,22 OFETs were biased in the transdiode regime (V DS ¼ V GS ) and a frequency modulated voltage v GS (f) superimposed on the DC gate bias. 6 By measuring the decoupled AC component of the current at both source and drain electrodes (i …”

High performance photolithographically-patterned polymer thin-film transistors gated with an ionic liquid/poly(ionic liquid) blend ion gel

“…Thus, there is scope for improvement regarding the dynamic behaviour of the device. Using nanopatterning methods such as nano-imprint lithography 39 or electron beam lithography 40 could be useful to explore the characteristics of the devices with a reduced footprint (smaller channel and electrode surface areas), while keeping a large W/L ratio. It was also previously reported that electrolyte-gated OTFTs with nanoscale channels perform better than OTFTs gated with conventional dielectrics, thanks to a much higher transverse electric field that limits undesirable short channel effects, which might render the operation of ion gel-gated organic nano-transistors possible.…”

Complementary Organic Logic Gates on Plastic Formed by Self‐Aligned Transistors with Gravure and Inkjet Printed Dielectric and Semiconductors

“…The fabrication process is discussed in detail in the Supporting Information and also in our previous work. [ 20 ] Figure 1 c-f) show the predominantly PL patterned (variants A + B) and printed (variants G + H) devices. The edges of the dielectric square are just visible in the optical micrographs (Figure 1c,d).…”

“…[ 20 ] Our approach also uses self-aligned lithography to minimize the overlap between the gate-source and gate-drain electrodes, reducing parasitic overlap capacitances that reduce the switching speed of OFETs. [ 21,22 ] Self-alignment yields other benefi ts such as overcoming equipment alignment tolerances, reducing leakage currents, and is compatible with more complex circuitry such as self-aligned unipolar ring oscillators.…”