- Molecular Design of Semiconducting Polymers for High-Performance Organic Electrochemical Transistors
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The organic electrochemical transistor (OECT), capable of transducing small ionic fluxes into electronic signals in an aqueous environment, is an ideal device to utilize in bioelectronic applications. Currently, most OECTs are fabricated with commercially available conducting poly(3,4-ethylenedioxythiophene) (PEDOT)-based suspensions and are therefore operated in depletion mode. Here, we present a series of semiconducting polymers designed to elucidate important structure-property guidelines required for accumulation mode OECT operation. We discuss key aspects relating to OECT performance such as ion and hole transport, electrochromic properties, operational voltage, and stability. The demonstration of our molecular design strategy is the fabrication of accumulation mode OECTs that clearly outperform state-of-the-art PEDOT-based devices, and show stability under aqueous operation without the need for formulation additives and cross-linkers.
- Nielsen, Christian B.,Giovannitti, Alexander,Sbircea, Dan-Tiberiu,Bandiello, Enrico,Niazi, Muhammad R.,Hanifi, David A.,Sessolo, Michele,Amassian, Aram,Malliaras, George G.,Rivnay, Jonathan,McCulloch, Iain
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- Regiochemistry-Driven Organic Electrochemical Transistor Performance Enhancement in Ethylene Glycol-Functionalized Polythiophenes
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Novel p-type semiconducting polymers that can facilitate ion penetration, and operate in accumulation mode are much desired in bioelectronics. Glycol side chains have proven to be an efficient method to increase bulk electrochemical doping and optimize aqueous swelling. One early polymer which exemplifies these design approaches was p(g2T-TT), employing a bithiophene-co-thienothiophene backbone with glycol side chains in the 3,3′ positions of the bithiophene repeat unit. In this paper, the analogous regioisomeric polymer, namely pgBTTT, was synthesized by relocating the glycol side chains position on the bithiophene unit of p(g2T-TT) from the 3,3′ to the 4,4′ positions and compared with the original p(g2T-TT). By changing the regio-positioning of the side chains, the planarizing effects of the S-O interactions were redistributed along the backbone, and the influence on the polymer's microstructure organization was investigated using grazing-incidence wide-angle X-ray scattering (GIWAXS) measurements. The newly designed pgBTTT exhibited lower backbone disorder, closer π-stacking, and higher scattering intensity in both the in-plane and out-of-plane GIWAXS measurements. The effect of the improved planarity of pgBTTT manifested as higher hole mobility (μ) of 3.44 ± 0.13 cm2 V-1 s-1. Scanning tunneling microscopy (STM) was in agreement with the GIWAXS measurements and demonstrated, for the first time, that glycol side chains can also facilitate intermolecular interdigitation analogous to that of pBTTT. Electrochemical quartz crystal microbalance with dissipation of energy (eQCM-D) measurements revealed that pgBTTT maintains a more rigid structure than p(g2T-TT) during doping, minimizing molecular packing disruption and maintaining higher hole mobility in operation mode.
- Hallani, Rawad K.,Paulsen, Bryan D.,Petty, Anthony J.,Sheelamanthula, Rajendar,Moser, Maximilian,Thorley, Karl J.,Sohn, Wonil,Rashid, Reem B.,Savva, Achilleas,Moro, Stefania,Parker, Joseph P.,Drury, Oscar,Alsufyani, Maryam,Neophytou, Marios,Kosco, Jan,Inal, Sahika,Costantini, Giovanni,Rivnay, Jonathan,McCulloch, Iain
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- Synthesis and characterization of all-conjugated diblock copolymers consisting of thiophenes with a hydrophobic alkyl and a hydrophilic alkoxy side chain
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Novel thiophene-based all-conjugated block copolymers consisting of 3-hexylthiophene and 3-{2-[2-(2-methoxyethoxy)ethoxy]ethoxy}thiophene were synthesized using the Grignard metathesis (GRIM) polymerization method in the presence of Ni(dppp)Cl2. Favorable transfer of the catalytic site from an electron-poor precursor to an electron-rich monomer was found to produce the block copolymer. The molecular weights of the copolymers increased slightly with increasing polymerization temperature (10.1 × 103 M n (35 °C) → 11.1 × 103 Mn (55 °C)), suggesting that transit of the catalytic site was accelerated at high temperatures. Size exclusion chromatography, UV-vis and photoluminescence spectroscopies, and cyclic voltammetry measurements confirmed that the polymers were block copolymers. The blocks were associated and organized relative to one another in adjacent chains.
- Kim, Jinseck,Siva, Ayyanar,Song, In Young,Park, Taiho
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- Conductive triethylene glycol monomethyl ether substituted polythiophenes with high stability in the doped state
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Synthesis of two conducting polymers containing 3-hexylthiophene and 3-[2-(2-(2-methoxyethoxy)ethoxy)ethoxy]thiophene is demonstrated. In thin-film transistors, the high-molecular-weight polymer shows an average mobility of 4.2 × 10?4 cm2 V?1 s?1. Most importantly, the polymers have high conductivity upon doping with iodine and also have high stability in the doped state with high conductivities measured even after 1 month. Furthermore, the doping causes transparency to thin films of the polymer and the films are resistant to common organic solvents. All these properties indicate a great potential for the iodine-doped polymer to be used as an alternative to commercially available poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate).
- Dissanayake, Dushanthi S.,Gunathilake, Samodha S.,Udamulle Gedara, Chinthaka M.,Du, Jia,Yoo, Sang Ha,Lee, Youngmin,Wang, Qing,Gomez, Enrique D.,Biewer, Michael C.,Stefan, Mihaela C.
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p. 1079 - 1086
(2019/03/21)
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- MOLECULAR FLUOROPHORES AND PREPARATION METHOD THEREOF AND USE FOR SHORT WAVELENGTH INFRARED IMAGING
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Provided is the design, synthesis and applications of molecular fluorophores for bioimaging in the short wavelength infrared window (1000-1700 nm). The molecular fluorophores compound comprise structures with electron accepting aromatic units, electron donating aromatic units, and an shielding units which shield the conjugated backbones from intermolecular interactions.
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Page/Page column 33-34
(2017/12/13)
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