Electroactive Polymers Prepared By Vapour Phase Polymerisation

Polymers are lightweight, flexible, solution-processible materials, which can possess insulating, semiconducting or metallic properties. Because of the high natural abundance of their constituting atoms, polymers are promising materials for low-cost printed electronics, mass produced and/or large-area applications. The conducting polymer poly(3,4-ethylenedioxythiophene), PEDOT, is one example material which displays (among others) high conductivity [1], and excellent thermoelectric properties [2].  Here, we report that when doped with tosylate and fabricated via vapour phase polymerization (VPP), the resulting PEDOT material is semi-metallic [2].  This material then forms the platform for a range of electrochromic applications. 

Through the use of variations to the VPP process, a range of electroactive thin films are prepared.  These cover complex multilayer structure, copolymerization of different conductive monomers, and spatial patterning.  Performance data on the switching of electrochromic devices based upon these polymer films show stability upwards of 10,000 switches.  Further enhancement of the electroactive polymers is achieved by incorporating within various 2D materials such as graphene [3].  In this extension, graphene- or MoS₂-PEDOT-tosylate nanocomposite films, ca. 170 nm thick, have been prepared by dispersing sterically stabilised nanosheets throughout an oxidant solution containing a triblock copolymer, with the liquid-like properties of the oxidant film under typical VPP conditions transporting the 2D nanomaterials into the forming PEDOT-tosylate film. The resulting composite film of graphene-PEDOT-tosylate has a 65% larger in-plane modulus when compared to the polymer only film, and can be used to facilitate the oxygen reduction reaction, with efficiencies equivalent to or greater than that of Pt [3]. 

[1] M.V. Fabretto, D.R. Evans, M. Mueller, K. Zuber, P. Hojati-Talemi, R.D. Short, G.G. Wallace, P.J. Murphy, Polymeric material with metal-like conductivity for next generation organic electronic devices, Chem. Mater., 24, 3998-4003, 2012

[2] O. Bubnova, Z.U. Khan, H. Wang, S. Braun, D.R. Evans, M.V. Fabretto, P. Hojati-Talemi, D. Dagnelund, J.-B. Arlin, Y. Geerts, S. Desbief, D. Breiby, J.W. Andreasen, R. Lazzaroni, W. Chen, I. Zozoulenko, M. Fahlman, P.J. Murphy, M. Berggren, X. Crispin, Semi-metallic polymers for thermoelectricity, Nat. Mater., 13, 190-194, 2014

[3] N. Vucaj, M.D.J. Quinn, C. Baechler, S.M. Notley, P. Cottis, P. Hojati-Talemi, M.V. Fabretto, G.G. Wallace, P.J. Murphy, D.R. Evans, Vapor phase synthesis of conducting polymer nanocomposites incorporating 2D nanoparticles, Chem. Mater., 26, 4207-4213, 2014