In situ growth of oriented polyaniline nanowires array for efficient cathode of Co(III)/Co(II) mediated dye-sensitized solar cell

To improve the electrocatalytic performance of polyaniline thin films, an oriented polyaniline nanowires array has been successfully grown in situ on conductive glass substrates without templates and applied as the cathode of dye-sensitized solar cells (DSSCs) mediated with a Co(bpy)3(3+/2+) (bpy 2,2'-bipyridine) redox couple. Compared to the polyaniline film with a random network, the oriented polyaniline nanowires array exhibits much better electrocatalytic performance, and even outperforms the typical Pt electrode in both electrocatalytic performance and electrochemical stability when exposed to the acetonitrile solution of the Co(bpy)(3)(3+/2+) redox couple. Owing to the higher electrocatalytic performance, the DSSC with the oriented nanowires array produces a higher short-circuit photocurrent and fill factor than the DSSCs with the random polyaniline network or Pt cathodes. Consequently, the power conversion efficiency of DSSCs based on a typical D-pi-A organic dye sensitizer increases from 5.97% for the polyaniline random network cathode to 8.24% for the oriented polyaniline nanowires array cathode, which is also higher than the efficiency (6.78%) of the DSSC with the Pt cathode.