Chemically synthesized poly(3,4-ethylenedioxythiophene) conducting polymer as a robust electrocatalyst for highly efficient dye-sensitized solar cells

Abstract

Chemically synthesized PEDOT (poly(3,4-ethylenedioxythiophene)) nanomaterials, having various nanostructured morphology with different intrinsic electrical conductivity and crystallinity, were compared as electrocatalyst for Co (III) reduction in dye-sensitized solar cells (DSSCs). The electrochemical parameters, charge transfer resistance toward electrode/electrolytes interface, catalytic activity for Co (III)-reduction, and diffusion of cobalt redox species greatly depend on the morphology, crystallinity, intrinsic electrical conductivity of chemically synthesized PEDOTs and optimization of fabrication procedure of counter electrodes. Spin-coated DMSO-dispersed PEDOT counter electrode by the ordered 1D structure of PEDOT, having nanosized fiber of average 70 nm diameter and electrical conductivity ~16 S cm-1, exhibit lowest charge transfer resistance, highest diffusion for cobalt redox mediator and superior electrocatalytic ability over traditional Pt-catalyst. The photovoltaic performance of DSSC using chemically synthesized PEDOT exceeds the performance of a Pt-electrode device because of the improvement of current density, which is directly related to the superior electrocatalytic ability of PEDOT toward Co (III)-reduction. This simple spin-coated counter electrode by cheap and scalable chemically synthesized PEDOT can be a potential alternative to the expensive Pt-counter electrode for cobalt and other redox electrolytes in DSSCs and various flexible electronic devices.