High Performance Organic Electrochemical Transistors and Logic Circuits Manufactured via a Combination of Screen and Aerosol Jet Printing Techniques

Abstract

Nowadays, most electronic gadgets comprise integrated circuits containing transistors, the key active components of modern electronics. Synthesis of novel organic materials has fostered the development of organic transistors controlled via electrolytic interfaces: (i) organic electrochemical transistors (OECT) and (ii) electrolyte-gated field-effect transistors (EGOFET); two devices that are governed by different operation mechanisms, partly originating from the features of the organic semiconductors used as channel materials. [7] In the OECT, charges are contained in the entire bulk of the organic semiconductor, giving rise to the high volumetric capacitance, resulting in high on-currents, high transconductance, high ON/OFF ratio, simplified device architectures, and low operation voltages of approximately 1 V. However, the enormous device capacitance also results in slow transistor response; this can be explained by the fact that the OECT relies on the movement of ions from the electrolyte into the bulk of the channel, and vice versa. Conversely, in EGOFETs, charges accumulate at the interface between the semiconductor and the electrolyte due to the electric double layers, resulting in shorter switching time, equally low switching voltages, similar ON/OFF ratio, but clearly lower current throughput. [8,9] Emerging application areas for organic transistors, especially OECTs, are biosensing, [10,11] electrophysiological recording, [12] neuromorphic devices, [13] and printed circuits. [3] The thickness of the electrolyte layer is noncritical from a device functionality point of view. In screen printed devices, the electrolyte thickness typically exceeds 10 µm, thereby paving the way for robust device architectures empowering large-scale manufacturing via reliable printing techniques. [14] An OECT is a three terminal device in which the source and drain electrodes are electronically connected via an organic semiconducting channel material, and a gate electrode is ionically linked to the channel by the electrolyte. Poly(3,4-ethylenedioxythiophene) doped with poly(styrene sulfonate) (PEDOT:PSS) is commonly used as the organic conjugated polymer in printed OECT channels. [15] Various OECT device architectures and materials have been explored in the last decade to improve the OECT switching response. As a result, by replacing PEDOT:PSS with carbon as the source and drain electrodes, short switching times and symmetric switching behavior have been reported in printed OECTs relying on PEDOT:PSS-based channels. [16] In 2017, This work demonstrates a novel fabrication approach based on the combination of screen and aerosol jet printing to manufacture fully printed organic electrochemical transistors (OECTs) and OECT-based logic circuits on PET substrates with superior performances. The use of aerosol jet printing allows for a reduction of the channel width to ≈15 µm and the estimated volume by a factor of ≈40, compared to the fully screen printed OECTs. Hence, the OECT devices and OECT-based logic circuits fabricated with ...

Fully Screen‐Printed Stretchable Organic Electrochemical Transistors

“…Altogether, these benefits have enabled innovative applications within biomolecule sensing, [10,11] neural recording, [12,13] and logic circuitry. [3,14,15] A variety of OECT structures of different complexity can be used depending on the performance requirements. In its simplest implementation, the length of the OECT channel is defined by the extent of the gate electrolyte, however this design yields severe hysteresis due to lateral ion movement outside of the channel.…”

“…[16,19] Although OECTs can be fabricated using traditional cleanroom techniques, [18] for scaling up it is more attractive to make use of solution processable materials in high-throughput printing processes for sustainable, low-temperature, low-waste, and low-toxicity production. To date, OECTs have been fabricated by a variety of printing methods, including inkjet, [20,21] aerosol jet, [15,22] 3D-printing, [23][24][25] and screen printing. Screen printing has emerged as an attractive scalable method for producing lateral and horizontal OECT designs, [19,26] comprising a variety of materials, into complex circuits.…”

“…Altogether, these benefits have enabled innovative applications within biomolecule sensing, [ 10,11 ] neural recording, [ 12,13 ] and logic circuitry. [ 3,14,15 ]…”

3D-Printed Intrinsically Stretchable Organic Electrochemical Synaptic Transistor Array

“…For example, all the components of the is-OECT, including electrodes, semiconducting layers, and dielectric layers, need to be stretchable and fabricated layer by layer. , The versatility of 3D printing enables the easy creation of highly customized and complex objects, making it a valuable tool for preparing OECTs. However, despite recent advances in 3D printing OECTs, ,− there are several challenges that need to be addressed for fully printed is-OECT. These challenges include limitations in developing printable inks with appropriate rheological behavior to achieve intrinsic stretchability. , Additionally, the high cost and low efficiency of the post-processing steps required after printing pose futher obstacles .…”

Biocompatible Ionic Liquids in High-Performing Organic Electrochemical Transistors for Ion Detection and Electrophysiological Monitoring

“…In particular, PEDOT:PSS has been the current state-of-the-art active conjugated polymer for organic electrochemical transistors (OECTs), where its conductivity can be modulated through the reversible exchange of ions present in the electrolyte under the application of a very low gate voltage ( V gs < 1 V). OECTs have therefore been extensively studied for bioelectronic applications owing to their large transconductance, low operating voltages, and ease of fabrication by printing. − …”