11 results found
Wu X, Surendran A, Moser M, et al., 2020, Universal Spray-Deposition Process for Scalable, High-Performance, and Stable Organic Electrochemical Transistors, ACS APPLIED MATERIALS & INTERFACES, Vol: 12, Pages: 20757-20764, ISSN: 1944-8244
Ohayon D, Nikiforidis G, Savva A, et al., 2020, Biofuel powered glucose detection in bodily fluids with an n-type conjugated polymer, NATURE MATERIALS, Vol: 19, Pages: 456-+, ISSN: 1476-1122
Wang Y, Zeglio E, Liao H, et al., 2019, Hybrid Alkyl-Ethylene Glycol Side Chains Enhance Substrate Adhesion and Operational Stability in Accumulation Mode Organic Electrochemical Transistors, CHEMISTRY OF MATERIALS, Vol: 31, Pages: 9797-9806, ISSN: 0897-4756
Savva A, Ohayon D, Surgailis J, et al., 2019, Solvent Engineering for High-Performance n-Type Organic Electrochemical Transistors, ADVANCED ELECTRONIC MATERIALS, Vol: 5, ISSN: 2199-160X
Moser M, Thorley KJ, Moruzzi F, et al., 2019, Highly selective chromoionophores for ratiometric Na+ sensing based on an oligoethyleneglycol bridged bithiophene detection unit, JOURNAL OF MATERIALS CHEMISTRY C, Vol: 7, Pages: 5359-5365, ISSN: 2050-7526
Moia D, Giovannitti A, Szumska AA, et al., 2019, Design and evaluation of conjugated polymers with polar side chains as electrode materials for electrochemical energy storage in aqueous electrolytes, Energy & Environmental Science, Vol: 12, Pages: 1349-1357, ISSN: 1754-5692
We report the development of redox-active conjugated polymers that have potential applications in electrochemical energy storage. Side chain engineering enables processing of the polymer electrodes from solution, stability in aqueous electrolytes and efficient transport of ionic and electronic charge carriers. We synthesized a 3,3′-dialkoxybithiophene homo-polymer (p-type polymer) with glycol side chains and prepared naphthalene-1,4,5,8-tetracarboxylic-diimide-dialkoxybithiophene (NDI-gT2) copolymers (n-type polymer) with either a glycol or zwitterionic side chain on the NDI unit. For the latter, we developed a post-functionalization synthesis to attach the polar zwitterion side chains to the polymer backbone to avoid challenges of purifying polar intermediates. We demonstrate fast and reversible charging of solution processed electrodes for both the p- and n-type polymers in aqueous electrolytes, without using additives or porous scaffolds and for films up to micrometers thick. We apply spectroelectrochemistry as an in operando technique to probe the state of charge of the electrodes. This reveals that thin films of the p-type polymer and zwitterion n-type polymer can be charged reversibly with up to two electronic charges per repeat unit (bipolaron formation). We combine thin films of these polymers in a two-electrode cell and demonstrate output voltages of up to 1.4 V with high redox-stability. Our findings demonstrate the potential of functionalizing conjugated polymers with appropriate polar side chains to improve the accessible capacity, and to improve reversibility and rate capabilities of polymer electrodes in aqueous electrolytes.
Zhang Y, Savva A, Wustoni S, et al., 2018, Visualizing the Solid-Liquid Interface of Conjugated Copolymer Films Using Fluorescent Liposomes, ACS Applied Bio Materials, Vol: 1, Pages: 1348-1354
Copyright © 2018 American Chemical Society. Conjugated polymers are promising engineering tools for establishing bilateral electrical communication with living systems. The free energy of their films, the roughness, and charge density play major roles in determining their interactions with lipid bilayers, which form the membrane barrier around every living cell allowing for molecular exchange with the extracellular environment. In this work, we investigate lipid bilayer formation from synthetic lipid vesicles (liposomes) on a series of amphiphilic copolymer films based on naphthalene 1,4,5,8 tetracarboxylic diimide bithiophene (NDI-T2) backbone where the alkyl side chain is gradually exchanged for an ethylene glycol-based side chain. As the concentration of ethylene glycol in the composition changes, the surface energy of the films varies drastically, which, in turn, effects the interactions with liposomes. By imaging the interactions of fluorophore-labeled liposomes with these surfaces via a fluorescence microscope, we show that the films can be cast such that ethylene glycol-rich regions, which liposomes favor, are accumulated on the surface and extract information on the wettability behavior that has not been possible using other surface sensitive techniques. This approach uncovers the solid/liquid interface of a promising class of electron transporting conjugated polymer films and suggests synthetic strategies to maximize the number of lipid-polymer contacts for the formation of supported lipid bilayers.
Du W, Ohayon D, Combe C, et al., 2018, Improving the Compatibility of Diketopyrrolopyrrole Semiconducting Polymers for Biological Interfacing by Lysine Attachment, CHEMISTRY OF MATERIALS, Vol: 30, Pages: 6164-6172, ISSN: 0897-4756
Venkatraman V, Friedlein JT, Giovannitti A, et al., 2018, Subthreshold operation of organic electrochemical transistors for biosignal amplification, Advanced Science, Vol: 5, ISSN: 2198-3844
With a host of new materials being investigated as active layers in organic electrochemical transistors (OECTs), several advantageous characteristics can be utilized to improve transduction and circuit level performance for biosensing applications. Here, the subthreshold region of operation of one recently reported high performing OECT material, poly(2‐(3,3′‐bis(2‐(2‐(2‐methoxyethoxy)ethoxy)ethoxy)‐[2,2′‐bithiophen]‐5‐yl)thieno[3,2‐b]thiophene), p(g2T‐TT) is investigated. The material's high subthreshold slope (SS) is exploited for high voltage gain and low power consumption. An ≈5× improvement in voltage gain (AV) for devices engineered for equal output current and 370× lower power consumption in the subthreshold region, in comparison to operation in the higher transconductance (g m), superthreshold region usually reported in the literature, are reported. Electrophysiological sensing is demonstrated using the subthreshold regime of p(g2T‐TT) devices and it is suggested that operation in this regime enables low power, enhanced sensing for a broad range of bioelectronic applications. Finally, the accessibility of the subthreshold regime of p(g2T‐TT) is evaluated in comparison with the prototypical poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), and the role of material design in achieving favorable properties for subthreshold operation is discussed.
Pappa A-M, Ohayon D, Giovannitti A, et al., 2018, Direct metabolite detection with an n-type accumulation mode organic electrochemical transistor, Science Advances, Vol: 4, ISSN: 2375-2548
The inherent specificity and electrochemical reversibility of enzymes poise them as the biorecognition element of choice for a wide range of metabolites. To use enzymes efficiently in biosensors, the redox centers of the protein should have good electrical communication with the transducing electrode, which requires either the use of mediators or tedious biofunctionalization approaches. We report an all-polymer micrometer-scale transistor platform for the detection of lactate, a significant metabolite in cellular metabolic pathways associated with critical health care conditions. The device embodies a new concept in metabolite sensing where we take advantage of the ion-to-electron transducing qualities of an electron-transporting (n-type) organic semiconductor and the inherent amplification properties of an ion-to-electron converting device, the organic electrochemical transistor. The n-type polymer incorporates hydrophilic side chains to enhance ion transport/injection, as well as to facilitate enzyme conjugation. The material is capable of accepting electrons of the enzymatic reaction and acts as a series of redox centers capable of switching between the neutral and reduced state. The result is a fast, selective, and sensitive metabolite sensor. The advantage of this device compared to traditional amperometric sensors is the amplification of the input signal endowed by the electrochemical transistor circuit and the design simplicity obviating the need for a reference electrode. The combination of redox enzymes and electron-transporting polymers will open up an avenue not only for the field of biosensors but also for the development of enzyme-based electrocatalytic energy generation/storage devices.
Giovannitti A, Maria I, Hanifi D, et al., 2018, The role of the side chain on the performance of n-type conjugated polymers in aqueous electrolytes, Chemistry of Materials, Vol: 30, Pages: 2945-2953, ISSN: 0897-4756
We report a design strategy that allows the preparation of solution processable n type materials from low boiling point solvents for organic electrochemical transistors (OECTs). The polymer backbone is based on NDI-T2 copolymers where a branched alkyl side chain is gradually exchanged for a linear ethylene glycol based side chain. A series of random copolymers are prepared with glycol side chain percentages of 0, 10, 25, 50, 75, 90 and 100 with respect to the alkyl side chains. These are characterized in order to study the influence of the polar side chains on interaction with aqueous electrolytes, their electrochemical redox reactions and performance in OECTs when operated in aqueous electrolytes. We observe that glycol side chain percentages of >50 % are required to achieve volumetric charging while lower glycol chain percentages show a mixed operation with high required voltages to allow for bulk charging of the organic semiconductor. A strong dependence of the electron mobility on the fraction of glycol chains was found for copolymers based on NDI-T2, with a significant drop as alkyl side chains are replaced by glycol side chains.
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