Solid‐State Homojunction Electrochemical Transistors and Logic Gates on Plastic

Abstract

Organic electrochemical transistors (OECTs) have attracted significant attention due to their unique ionic-electronic charge coupling, which holds promise for use in a variety of bioelectronics. However, the typical electronic components of OECTs, such as the rigid metal electrodes and aqueous electrolytes, have limited their application in solid-state bioelectronics that requires design flexibility and a variety of form factors. Here, the fabrication of a solid-state homojunction OECT consisting of a pristine polymer semiconductor channel, doped polymer semiconductor electrodes, and a solid electrolyte is demonstrated. This structure combines the photo-crosslinking of all of the electronic OECT components with the selective doping of the polymer semiconductor. Three Lewis acids (gold (III) chloride (AuCl 3 ), iron (III) chloride (FeCl 3 ), and copper (II) chloride (CuCl 2 ) ) are utilized as dopants for the metallization of the polymer semiconductor. The AuCl 3 -doped polymer semiconductor with an electrical conductivity of ≈100 S cm −1 is successfully employed as the source, drain, and gate electrodes for the OECT, which exhibited a high carrier mobility of 3.4 cm 2 V −1 s −1 and excellent mechanical stability, with negligible degradation in device performance after 5000 cycles of folding at a radius of 0.1 mm. Homojunction OECTs are then successfully assembled to produce NOT, NAND, and NOR logic gates.

All‐Photolithography Fabrication of Ion‐Gated Flexible Organic Transistor Array for Multimode Neuromorphic Computing

“…When V DD = 1.2 V, the inverter demonstrates the highest gain of 11.48 (Figure 2K), which is comparable to or higher than the performance of IGTbased inverters reported in the literature. [32,51,52] The aforementioned results indicate that the modified all-photolithography method can be used for the construction of complex logic circuits.…”

Device design principles and bioelectronic applications for flexible organic electrochemical transistors

“…Thus, the development of foundry-compatible organic semiconductors patterning methods that maintains device performance has potentially revolutionize the OECT industry [142,143]. Recently, Kwak et al reported photo-patternable organic mixed ionic and electronic conductors (OMIECs) by introducing a photocross-linkable material (thane-1,2-diyl bis(4-azido-2,3,5,6 tetrafluorobenzoate)) into ion-conducting conjugated polymers to address these challenges (figure 4(b)).…”

“…This chemistry of the cross-linking reactions involving azido compounds relies on the highly efficient and selective click chemistry reactions, enabling the formation of stable and robust crosslinkages in polymer networks. The patterning technique is exceptionally efficient as it only necessitates three steps, making the manufacture process simpler than conventional photolithography [142], in which a blend film of semiconductor/electrolyte and crosslinkers can be patterned directly via UV light-triggered crosslinking. With this patterning technology, flexible OECTs were evaluated and presented high carrier mobility (3.4 cm 2 V −1 s −1 ) and reliabe mechanical stability, with minimal degradation in OECT output performance, even after undergoing 5000 bending cycles at radius of only 0.1 mm.…”

On the fundamentals of organic mixed ionic/electronic conductors

“…Molecular doping strategies have been applied to OMIECs, both for p-and n-type materials, which have been successful in modulating current densities, shifting threshold voltages, minimizing side reactions, and improving long-term stability in OECTs. [74][75][76] Other small molecule additives have been employed to improve the output characteristics of OECTs. 77 Moreover, the de-doping of PEDOT:PSS has been achieved by promoting interactions between amine groups and PSS-, allowing the generate a polymer for use in enhancement mode OECTs.…”