A new low bandgap hybrid polymer film obtained by electropolymerization of 3,4-ethylenedioxythiophene with bis(1,3-dithiole-2-thione-4,5-dithiolate)platinate(II) dianion, PEDOT/[Pt(dmit)2]2−

Abstract

In this work, we report the electrochemical polymerization of novel low bandgap hybrid polymer films based on 3,4-ethylenedioxythiophene containing bis(1,3-dithiole-2-thione-4,5-dithiolate)platinate(II) dianions, PEDOT/[Pt(dmit)2]2− which were obtained under galvanostatic conditions using a synthesis charge (Qs) of 12.5 mC cm−2. Morphological studies of these films by SEM and AFM revealed a regular surface with volumetric roughness (RMS) of 141.8 nm as well as high homogeneity in its composition. FTIR studies depicted bands assigned to both polymer and counterions, confirming a strong interaction among the components. Cyclic voltammetry in a monomer free solution showed well-defined peaks and potentials similar to that of the free counterion, evincing that the electron transfer processes in the film are mainly ruled by the dmit-based counterion. Optoelectronics studies of hybrid films showed a strong absorption at 786 nm and a multicolor electrochromism (greenish yellow-deep green). The direct optical bandgap (Eg), calculated from the absorption spectrum, was 1.42 eV, suggesting that the dmit-based dianion plays an important role on the optoelectronic properties of the hybrid polymer films.