Effect of the fullerene in the properties of thin PEDOT/C60films obtained by co-electrodeposition

Organic electronics requires the development of reproducible and highly conductive thin films. The arrangement of poly(3,4-ethylenedioxythiophene) (PEDOT) with fullerene C60 leads to products with the combined properties of both species that are excellent candidates for these applications. However, very little has been studied about the effect of doping PEDOT with C60, and thus there is a lack of information regarding the morphology, electrochemical and electrochromic properties of the resulting films. Herein, simultaneous electrodeposition of poly(3,4-ethylenedioxythiophene) (PEDOT) doped with fullerene C60 was carried out via cyclic voltammetry in the range from 0.0 V to +1.5 V (vs Ag/AgCl) in a three-compartment cell. ITO coated on PET was used as both working and counter electrodes. The fullerene presence within the films was confirmed with MALDI and TGA (27.5% of fullerene content). The cyclic voltamograms showed that the C60-doped film has a higher oxidation potential, what was attributed to the electron affinity of the fullerene cage. Furthermore, the spectroelectrochemical and electrochromic analyses showed that the PEDOT/C60 films present a dark violet coloration in the reduced state, which differs from the usual dark blue of the PEDOT polymer. Finally, the morphology was analyzed using AFM and SEM, and pillar structure of broccoli-like particles was observed for both films. However, the fullerene doping generated smaller polymer-based particles, thus forming a denser structure with higher surface area, suggesting the use of the cages as nucleation points for the polymerization.