Dye-sensitized solar cells with low-cost catalytic films of polymer-loaded carbon black on their counter electrode

Abstract

Dye-sensitized solar cells (DSSCs), consisting of counter electrodes (CEs) with composite films made of carbon black (CB) and conducting polymers such as polypyrrole (PPy) and polyaniline (PANI), were fabricated. A slurry was first prepared with 99 wt% of conducting polymer-loaded CB using the requisite 1 wt% of poly(oxyethylene)-segmented imide (POEM) as the dispersant in ethanol. The conducting polymer-loaded CB was a commercial product with a composition of about 80 wt% of CB and 20 wt% of conducting polymer. The POEM dispersant was required to generate a homogeneous dispersion of the carbon material in the ethanolic solution. The dispersive ability of POEM for CB was demonstrated both visually and through UV–vis absorption spectra and the dynamic light scattering method (DLS). The slurries with PPy/CB and PANI/CB were coated on FTO glasses to prepare CEs for DSSCs. The DSSCs with CEs containing PPy/CB and PANI/CB have shown power conversion efficiencies (η) of 5.85 ± 0.23% and 6.77 ± 0.13%, respectively, while the cells with CEs containing bare CB and bare platinum have shown η's of 5.35% and 7.24 ± 0.11%, respectively. The dispersive function of POEM for CB to impart high electrocatalytic abilities on the corresponding CEs was responsible for the better performance of the cells for both PPy/CB and PANI/CB than that of the cell with bare CB. Hydrogen-1 nuclear magnetic resonance (¹H-NMR), gel permeation chromatography (GPC), scanning electronic microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), incident photo-to-current conversion efficiency (IPCE) spectra, Tafel polarization plots, and rotating disk electrode measurements (RDE) were used to substantiate the explanations.