Counter electrodes for DSC: Application of functional materials as catalysts

Counter electrodes (CEs) of dye-sensitized solar cells (DSCs) can be prepared with different materials and methods. This review covers recent research on CEs using platinum, graphite, activated carbon, carbon black, single-wall carbon nanotubes, poly(3,4-ethylenedioxythiophene) (PEDOT), polypyrrole, and polyaniline as catalysts for reduction of triiodide. Moreover, for the ultimate in low-cost counter electrodes, we have prepared a carbon-black-loaded stainless steel electrode for use as a novel CE. This counter electrode exhibits good photovoltaic performance; the efficiency reaches 9.15% (16.3 mA cm⁻²J_sc, 785 mV V_oc, and 71.4% fill factor) with SUS-316 stainless steel, equivalent to the performance with an FTO-glass substrate.