Submicron Vertical Channel Organic Electrochemical Transistors with Ultrahigh Transconductance

Abstract

Organic electrochemical transistors (OECTs) belong to the class of electrolyte gated organic transistors (EGOTs) that offer a smooth interface with biology in combination with high transconductance values of typically a few mS. Fabrication‐wise, though, most of the up‐to‐date reported devices are limited to two dimensional structures, where the transistor channel is patterned on the same plane as the source and drain electrodes. Here, a method is introduced for the fabrication of integrated vertical channel OECTs (vOECTs) with submicron channel length. By employing electrodeposition, a vertical channel sandwiched between the source and drain electrodes is created. Channel lengths down to 60 nm are demonstrated, giving rise to ultrahigh transconductance of up to 275 mS. Accounting for the voltage loss on the device connection tracks, an intrinsic transconductance of vOECTs of 500 mS is found. The vOECTs are three‐dimensional transistors finding relevant application in “organ‐on‐a‐chip” and implantable devices, where high amplification and small footprint are demanded.

Organic Bioelectronics Development in Italy: A Review

“…From a technological point of view, fabrication techniques derived from silicon technology are exploited [ 39 , 57 , 63 , 64 , 65 , 66 ], as well as 2D and 3D printing technologies [ 7 , 54 , 67 , 68 , 69 , 70 , 71 ]. Moreover, increasingly accurate models have been developed in order to better understand the physical mechanisms governing the device operations, both in terms of the electrolyte-gating working mechanisms and in terms of the biosensor’s response to a given analyte [ 55 , 56 , 59 , 72 ].…”

“…A different approach was exploited by Koutsouras et al who developed a vertical channel OECT (vOECT) [ 64 ]. An electrodeposited PEDOT:PSS layer sandwiched between the source and drain electrodes acted as an active device channel, with the length defined by the film thickness.…”

Effect of ionic conductivity of electrolyte on printed planar and vertical organic electrochemical transistors

“…Recently, electropolymerization has been used for the deposition of a PEDOT:PSS channel material on photolithographically patterned gold bottom electrodes, followed by gold deposition using a shadow mask as the top electrode. 19 Transconductances in the range of 30–275 mS were reported for these devices, depending on the channel length and width. Vertical structures have also been reported with semiconducting channel materials such as diketopyrrolopyrrole–terthiophene donor–acceptor polymer (PDPP) and poly(3-hexylthiophene) (P3HT).…”

“…Most OECTs reported to date have planar structures, and there are few reports on vertical OECTs. 17–20…”

Real‐Time Monitoring of Cellular Barrier Functionality with Dynamic‐Mode Current‐Driven Organic Electrochemical Transistor

“…The gate and the channel are in direct contact with an electrolyte and the polarity and magnitude of the applied gate voltage (V G ) give rise a drift of anions or cations from the electrolyte to the channel and vice versa. [20][21][22][23][24] When an OECT is used to measure a barrier tissue, the biological barrier can be placed in-between the gate and the channel. In this configuration, the ion transport depends on the barrier status that, in turn, is mirrored by the electrical characteristics of the OECT.…”