title: Controlling the mode of operation of organic transistors through side-chain engineering.
abstract: Electrolyte-gated organic transistors offer low bias operation facilitated by direct contact of the transistor channel with an electrolyte. Their operation mode is generally defined by the dimensionality of charge transport, where a field-effect transistor allows for electrostatic charge accumulation at the electrolyte/semiconductor interface, whereas an organic electrochemical transistor (OECT) facilitates penetration of ions into the bulk of the channel, considered a slow process, leading to volumetric doping and electronic transport. Conducting polymer OECTs allow for fast switching and high currents through incorporation of excess, hygroscopic ionic phases, but operate in depletion mode. Here, we show that the use of glycolated side chains on a thiophene backbone can result in accumulation mode OECTs with high currents, transconductance, and sharp subthreshold switching, while maintaining fast switching speeds. Compared with alkylated analogs of the same backbone, the triethylene glycol side chains shift the mode of operation of aqueous electrolyte-gated transistors from interfacial to bulk doping/transport and show complete and reversible electrochromism and high volumetric capacitance at low operating biases. We propose that the glycol side chains facilitate hydration and ion penetration, without compromising electronic mobility, and suggest that this synthetic approach can be used to guide the design of organic mixed conductors.
authors: Department of Chemistry and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, United Kingdom.
authors: Alexander
authors: A
authors: Giovannitti
authors: Department of Chemistry and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, United Kingdom.
authors: Dan-Tiberiu
authors: DT
authors: Sbircea
authors: Department of Bioelectronics, École Nationale Supérieure des Mines de Saint-Etienne, Centre Microélectronique de Provence (CMP-EMSE), Microelectronique et Objects Communicants, 13541 Gardanne, France; Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology (KAUST) Thuwal, 23955-6900, Saudi Arabia.
authors: Sahika
authors: S
authors: Inal
authors: Department of Chemistry and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, United Kingdom; Materials Research Institute and School of Biological and Chemical Sciences, Queen Mary University of London, London E1 4NS, United Kingdom.
authors: Christian B
authors: CB
authors: Nielsen
authors: Instituto de Ciencia Molecular, Universidad de Valencia, Paterna 46980, Spain.
authors: Enrico
authors: E
authors: Bandiello
authors: Department of Chemistry, Stanford University, Stanford, CA 94305.
authors: David A
authors: DA
authors: Hanifi
authors: Instituto de Ciencia Molecular, Universidad de Valencia, Paterna 46980, Spain.
authors: Michele
authors: M
authors: Sessolo
authors: Department of Bioelectronics, École Nationale Supérieure des Mines de Saint-Etienne, Centre Microélectronique de Provence (CMP-EMSE), Microelectronique et Objects Communicants, 13541 Gardanne, France.
authors: George G
authors: GG
authors: Malliaras
authors: Department of Chemistry and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, United Kingdom; Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Saudi Arabia.
authors: Iain
authors: I
authors: McCulloch
authors: Department of Bioelectronics, École Nationale Supérieure des Mines de Saint-Etienne, Centre Microélectronique de Provence (CMP-EMSE), Microelectronique et Objects Communicants, 13541 Gardanne, France; Palo Alto Research Center - a Xerox company, Palo Alto, CA 94304 jonathan.rivnay@parc.com.
authors: Jonathan
authors: J
authors: Rivnay
keywords: electrochemical transistor; organic electronics; semiconducting polymers