Redox-Stability of Alkoxy-BDT Copolymers and their Use for Organic Bioelectronic Devices
Thorley, Karl J.
Nielsen, Christian B.
Donahue, Mary J.
Malliaras, George G.
KAUST DepartmentPhysical Sciences and Engineering (PSE) Division
Chemical Science Program
KAUST Solar Center (KSC)
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AbstractOrganic semiconductors can be employed as the active layer in accumulation mode organic electrochemical transistors (OECTs), where redox stability in aqueous electrolytes is important for long-term recordings of biological events. It is observed that alkoxy-benzo[1,2-b:4,5-b′]dithiophene (BDT) copolymers can be extremely unstable when they are oxidized in aqueous solutions. The redox stability of these copolymers can be improved by molecular design of the copolymer where it is observed that the electron rich comonomer 3,3′-dimethoxy-2,2′-bithiophene (MeOT2) lowers the oxidation potential and also stabilizes positive charges through delocalization and resonance effects. For copolymers where the comonomers do not have the same ability to stabilize positive charges, irreversible redox reactions are observed with the formation of quinone structures, being detrimental to performance of the materials in OECTs. Charge distribution along the copolymer from density functional theory calculations is seen to be an important factor in the stability of the charged copolymer. As a result of the stabilizing effect of the comonomer, a highly stable OECT performance is observed with transconductances in the mS range. The analysis of the decomposition pathway also raises questions about the general stability of the alkoxy-BDT unit, which is heavily used in donor-acceptor copolymers in the field of photovoltaics.
CitationGiovannitti A, Thorley KJ, Nielsen CB, Li J, Donahue MJ, et al. (2018) Redox-Stability of Alkoxy-BDT Copolymers and their Use for Organic Bioelectronic Devices. Advanced Functional Materials: 1706325. Available: http://dx.doi.org/10.1002/adfm.201706325.
SponsorsThe authors thank King Abdullah University of Science and Technology, Badische Anilin and Soda Fabrik, Engineering and Physical Sciences Research Council Project EP/G037515/1, EP/M005143/1, EP/N509486/1, EC FP7 Project SC2 (610115), and EC H2020 Project SOLEDLIGHT (643791) for the financial support.
JournalAdvanced Functional Materials