Enhanced performance of low-cost dye-sensitized solar cells with pulse-electropolymerized polyaniline counter electrodes

In this study, the pulse potentiostatic electropolymerization of anilines was employed in synthesizing polyaniline (PANI) nanofibers with rough surface morphology onto a fluorinated tin oxide (FTO) glass substrate as a Pt-free counter electrode (CE) for low-cost dye-sensitized solar cells (DSCs) for the first time. A variety of pulse parameters were investigated to control the surface morphology of PANI nanofibers. After the optimization, the well-distributed rough PANI nanofibers with the diameter of 100 nm can be obtained under 1.1 V pulse-on potential, 0 V pulse-reversal potential, 1 s pulse-on period, 0.5 s pulse-reversal period, and total 150 s duration time. The extensive cyclic voltammograms revealed that the pulsed PANI CE not only had superior electrocatalytic activity for I3− reduction, but also exhibited excellent electrochemical stability. Moreover, the electrochemical impedance spectroscopy showed the pulsed PANI CE had the relatively lower series resistance and charge-transfer resistance than those of the PANI CE prepared by the conventional potentiostatic (I–t) electropolymerization. Therefore, the DSC assembled with the pulsed PANI CE exhibited an enhanced photovoltaic conversion efficiency of 5.19% (compared to 4.35% for the DSC with the I–t PANI CE) up to ∼90% level of the DSC using the Pt CE. As the result, the pulsed PANI CE can be considered as a promising alternative CE for low-cost DSCs.

► PANI nanofiber with rough morphology was obtained using pulse electropolymerization.
► The pulsed PANI CE showed the enhanced electrocatalytic activity for I3− reduction.
► The cell efficiency of the low-cost DSC is up to 90% level of that using Pt CE.