Layer-by-Layer Assembly Monitored by PEDOT-Polyamine-Based Organic Electrochemical Transistors

Abstract

In this work, we present the fabrication of PEDOT–PAH-based organic electrochemical transistors (OECTs), that are employed to monitor the deposition of polyelectrolyte multilayers on their surface. We first explore different synthesis conditions in order to optimize the electrical characteristics of the devices, such as threshold voltage and voltage of maximum transconductance. Next, the transistors showing the desired features are chosen to investigate the process of the layer-by-layer (LbL) assembly through (i) the analysis of the transfer characteristics curves and (ii) the changes in the registered drain–source current. It is demonstrated that the OECTs are able to monitor the assembly of the different polyelectrolyte layers in real time in both modes of operation, yielding information about conductivity and surface potential changes in the channel. Next, the transient characteristics of the devices are studied upon the assembly of the different layers, providing information about the changes in the ionic transport through the whole film during the ON and OFF switching. Finally, the kinetic response of the OECTs toward the monitoring of charged macromolecules is fitted to a two-step adsorption model and compared against graphene field-effect transistors and surface plasmon resonance. The monitoring of the LbL assembly by the changes in the PEDOT–PAH OECT response illustrates the use of these transistors for sensing interactions with charged species in solution and supports the development of sensing platforms by integration of specific recognition elements on the conducting polymer channel.

Empowering Bioelectronics with Supramolecular Nanoarchitectonics: PEDOT-Based Organic Electrochemical Transistors with Tunable Electronic Properties

“…Although the LbL technique has been widely used for the construction of different functional interfaces, it has been little explored for the preparation of PEDOT films with integrated components that constitute the active channel of OECTs devices. While certain studies have delved into enhancing the functionality of the pre-existing PEDOT-based conducting channel through the application of a coating via LbL assembly of insulating polyelectrolytes for various purposes, − the potential benefits of the LbL method for precisely incorporating the PEDOT building block and thereby augmenting the thickness of the conducting channel have been relatively underexplored. In this regard, Zhu et al have recently reported the LbL preparation of PEDOT-based conducting channels on cotton fibers using PEDOT:PSS and poly­(diallyl­dimethyl­ammonium chloride) (PDADMAC) as counter polyelectrolytes for the fabrication of OECTs that allow the detection of sialic acid .…”

Interface Engineering of “Clickable” Organic Electrochemical Transistors toward Biosensing Devices

“…In this regard, the functionalization of PEDOT is usually hindered by the lack of functional moieties in as-prepared films. 8,12 Likewise, the polyanion excess in PEDOT:PSS films limits their interactions with most biological elements (such as proteins, nucleic acids, and cells) since they present negative charges at physiological conditions. 13,14 A particularly interesting approach to improve the biocompatibility and/or facilitate the functionalization of PEDOT (and PEDOT:PSS)-based films involves the derivatization of the EDOT monomer with a desired molecule/ biorecognition element and its subsequent polymerization.…”

“…Regarding the channel material of OECTs, poly­(3,4-ethylenedioxythiophene) (PEDOT) and its water-stable colloidal complex with poly­(styrenesulfonate) (PEDOT:PSS) have been the most employed polymers due to the high electronic conductivity of PEDOT and the excellent processability of PEDOT:PSS. , However, there are challenges that still need to be overcome; PEDOT’s intrinsic doping yields devices with high threshold voltages ( V TH ), meaning the necessity of high gate voltages to maintain the channel in the OFF state, therefore causing parasitic reactions with the electrolyte and prompting the deterioration of the devices. , Another major issue yet to surpass implies the interfacing of these materials with biological systems. In this regard, the functionalization of PEDOT is usually hindered by the lack of functional moieties in as-prepared films. , Likewise, the polyanion excess in PEDOT:PSS films limits their interactions with most biological elements (such as proteins, nucleic acids, and cells) since they present negative charges at physiological conditions. , …”

Transduction of Amine–Phosphate Supramolecular Interactions and Biosensing of Acetylcholine through PEDOT-Polyamine Organic Electrochemical Transistors

“…Therefore, in the last years, researchers have explored different methods to tailor the surface of PEDOT and PEDOT:PSS films . A particularly interesting approach involves the incorporation of amines moieties to the channel material, thus conferring anchoring sites for further biofunctionalization of the conducting polymer. , In this context, the recent development of OECTs employing PEDOT:TOS and poly(allylamine hydrochloride) (PAH) composites as conducting channel materials represents a significant advancement in the field. , The regulation of the PAH:PEDOT ratio allows for the straightforward tuning of both electronic and ionic transport of the devices, producing transistors with low threshold voltages while maintaining high transconductance values. Moreover, the pH-sensitive amino moieties in the PEDOT matrix improve the pH response of the transistors and enable the nondenaturing electrostatic anchoring of functional enzymes such as acetyl­cholinesterase (AchE) …”

“…33,34 In this context, the recent development of OECTs employing PEDOT:TOS and poly(allylamine hydrochloride) (PAH) composites as conducting channel materials represents a significant advancement in the field. 35,36 The regulation of the PAH:PEDOT ratio allows for the straightforward tuning of both electronic and ionic transport of the devices, producing transistors with low threshold voltages while maintaining high transconductance values. Moreover, the pH-sensitive amino moieties in the PEDOT matrix improve the pH response of the transistors and enable the nondenaturing electrostatic anchoring of functional enzymes such as acetylcholinesterase (AchE).…”