Dye-sensitized solar cells with high-performance polyaniline/multi-wall carbon nanotube counter electrodes electropolymerized by a pulse potentiostatic technique

Abstract

Strong scientific interests focus on the investigation of Pt-free counter electrodes (CEs) for their application in dye-sensitized solar cells (DSCs). Here we demonstrate the synthesis of a high-performance polyaniline/multi-wall carbon nanotube (PANI/MWCNT) nanocomposite CE via electrophoresis of MWCNTs onto a fluorinated tin oxide (FTO) substrate and then subjected to PANI electropolymerization by using the pulse potentiostatic method. The resultant rough PANI thin film around the MWCNT is ∼45 nm in thickness. Cyclic voltammetry, electrochemical impedance spectroscopy, and Tafel polarization measurements reveal that PANI/MWCNT CE possesses an enhanced electrocatalytic activity for I3− reduction compared to PANI and MWCNT CEs due to its intrinsic superior electrocatalytic activity of the PANI material and high surface area of the MWCNTs. The DSC assembled with the pulsed PANI/MWCNT CE exhibits the superior photovoltaic conversion efficiency of 6.24% (compared to 5.18% for DSCs with PANI CE or 6.05% for DSCs with Pt CE) under full sunlight illumination (100 mW cm−2, AM1.5 G). Therefore, the high-performance PANI/MWCNT can be considered as a cost-effective CE alternative for DSCs.