Downsizing the Channel Length of Vertical Organic Electrochemical Transistors

• Organic electrochemical transistors (OECTs) are promisingbuildingblocks for bioelectronic devices such as sensors and neural interfaces.While the majority of OECTs use simple planar geometry, there is interestin exploring how these devices operate with much shorter channelson the submicron scale. Here, we show a practical route toward theminimization of the channel length of the transistor using traditionalphotolithography, enabling large-scale utilization. We describe thefabrication of such transistors using two types of conducting polymers.First, commercial solution-processed poly-(dioxyethylenethiophene):poly-(styrenesulfonate), PEDOT:PSS. Next, we also exploit the short channel lengthto support easy in situ electropolymerization of poly-(dioxyethylenethiophene):tetrabutylammonium hexafluorophosphate, PEDOT:PF6. Both variantsshow different promising features, leading the way in terms of transconductance(g (m)), with the measured peak g (m) up to 68 mS for relatively thin (280 nm) channel layerson devices with the channel length of 350 nm and with widths of 50,100, and 200 & mu;m. This result suggests that the use of electropolymerizedsemiconductors, which can be easily customized, is viable with verticalgeometry, as uniform and thin layers can be created. Spin-coated PEDOT:PSSlags behind with the lower values of g (m); however, it excels in terms of the speed of the device and alsohas a comparably lower off current (300 nA), leading to unusuallyhigh on/off ratio, with values up to 8.6 x 10(4). Ourapproach to vertical gap devices is simple, scalable, and can be extendedto other applications where small electrochemical channels are desired.

Ämnesord

NATURVETENSKAP  -- Data- och informationsvetenskap -- Datorteknik (hsv//swe)

NATURAL SCIENCES  -- Computer and Information Sciences -- Computer Engineering (hsv//eng)

Nyckelord

vertical organic electrochemical transistor; microfabrication; PEDOT; electrochemical polymerization

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