A guide for the characterization of organic electrochemical transistors and channel materials

Ohayon, David; Druet, Victor; Inal, Sahika

doi:10.1039/d2cs00920j

Cited by 76 publications

(90 citation statements)

References 172 publications

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“…Conjugated polymers have emerged as a highly promising class of organic mixed ionic–electronic conductors (OMIECs). Their structure, featuring a conjugated backbone that facilitates electron or hole transport and side chains that enable ion transport, makes them ideal for a variety of applications that take advantage of mixed conductivity including biosensors for wearable devices, − neuromorphic computing, , organic electrochemical transistors (OECTs) for bioelectronics, − thermoelectrics, , and energy storage devices. − The majority of these technologies rely on electrochemical doping, which involves the injection of electrons or holes into the polymer from an underlying electrode, resulting in the entry of ions from an adjacent electrolyte into the polymer matrix. , This process can lead to volumetric capacitances up to 1000 F/cm 3 . Additionally, electrochemical doping can cause reversible structural changes in OMIECs due to the injection of ions or rearrangement of water molecules in the polymer matrix. ,− …”

Section: Introductionmentioning

confidence: 99%

Crystallinity Determines Ion Injection Kinetics and Local Ion Density in Organic Mixed Conductors

et al. 2023

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Conjugated polymer organic mixed ionic–electronic conductors (OMIECs) consist of a complex arrangement of crystalline and amorphous regions at the nanoscale. The arrangement of ions in this heterogeneous environment upon electrochemical doping influences the performance of devices that leverage mixed conductivity. This study investigates how varying the ratio of amorphous and crystalline content affects the distribution of ions in blends of regiorandom (RRa) and regioregular (RR) poly(3-hexylthiophene) (P3HT). By correlating changes in the polymer lattice spacing upon ion uptake with spectroelectrochemistry measurements of polaron formation, we find that ions enter the crystalline regions of the polymer first. Using nanoscale infrared imaging with photoinduced force microscopy (PiFM) of the infrared-active PF6 – ions, we map the location of ions at the nanoscale and show that ions cluster in crystalline regions of P3HT thin films. We correlate the infrared images of ion locations with visible PiFM (785 nm) to map the presence of polarons in the film and find that the locations of ions and polarons are correlated. This study also reveals that balancing the distribution of amorphous and crystalline regions can enhance ion injection kinetics. These results underline the importance of controlling the nanoscale morphology of conjugated polymers for high-performing OMIECs.

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Section: Introductionmentioning

confidence: 99%

Crystallinity Determines Ion Injection Kinetics and Local Ion Density in Organic Mixed Conductors

et al. 2023

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“…When aiming to improve the amplification or speed properties of the OECT, the channel material and geometry are the main factors to consider. − The OECT amplification, or transconductance ( g m ), is directly proportional to the electronic charge carrier mobility, μ, and the volumetric channel capacitance ( C *)–intrinsic material properties. In contrast, its dependence on the channel width ( W ), thickness ( d ), and length ( L ) (i.e., the channel volume), g m ∼ Wd/L , allows for manipulation through engineering approaches.…”

Section: Introductionmentioning

confidence: 99%

Downsizing the Channel Length of Vertical Organic Electrochemical Transistors

Brodský

Gablech

Migliaccio

et al. 2023

ACS Appl. Mater. Interfaces

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Organic electrochemical transistors (OECTs) are promising building blocks for bioelectronic devices such as sensors and neural interfaces. While the majority of OECTs use simple planar geometry, there is interest in exploring how these devices operate with much shorter channels on the submicron scale. Here, we show a practical route toward the minimization of the channel length of the transistor using traditional photolithography, enabling large-scale utilization. We describe the fabrication of such transistors using two types of conducting polymers. First, commercial solution-processed poly(dioxyethylenethiophene):poly(styrene sulfonate), PEDOT:PSS. Next, we also exploit the short channel length to support easy in situ electropolymerization of poly(dioxyethylenethiophene):tetrabutyl ammonium hexafluorophosphate, PEDOT:PF 6 . Both variants show 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 layers on devices with the channel length of 350 nm and with widths of 50, 100, and 200 μm. This result suggests that the use of electropolymerized semiconductors, which can be easily customized, is viable with vertical geometry, as uniform and thin layers can be created. Spincoated PEDOT:PSS lags behind with the lower values of g m ; however, it excels in terms of the speed of the device and also has a comparably lower off current (300 nA), leading to unusually high on/off ratio, with values up to 8.6 × 10 4 . Our approach to vertical gap devices is simple, scalable, and can be extended to other applications where small electrochemical channels are desired.

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“…10 Ions must enter and exit the film to balance charges introduced by the redox chemistry of the conjugated backbone. 11 However, classical CPs are often hydrophobic as a result of their alkyl side chains and aromatic building blocks. 12 In order to promote the ionic conductivity in aqueous electrolytes, the polarity of the CPs can be modulated to increase their hydrophilic feature.…”

Section: Introductionmentioning

confidence: 99%

“…10 Ions must enter and exit the film to balance charges introduced by the redox chemistry of the conjugated backbone. 11…”

Section: Introductionmentioning

confidence: 99%

Tunable control of the performance of aqueous-based electrochemical devices by post-polymerization functionalization

et al. 2023

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A guide for the characterization of organic electrochemical transistors and channel materials

Abstract: The organic electrochemical transistor (OECT) is one of the most versatile bioelectronic devices. This review is a guide for how to characterize OECTs and monitor the mixed charge transport and swelling properties of the OECT channel materials.

Cited by 76 publications

References 172 publications

Crystallinity Determines Ion Injection Kinetics and Local Ion Density in Organic Mixed Conductors

Crystallinity Determines Ion Injection Kinetics and Local Ion Density in Organic Mixed Conductors

Downsizing the Channel Length of Vertical Organic Electrochemical Transistors

Tunable control of the performance of aqueous-based electrochemical devices by post-polymerization functionalization

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