Axle-sleeve Structured MWCNTs/Polyaniline Composite Film as Cost-effective Counter-Electrodes for High Efficient Dye-Sensitized Solar Cells

•Axle-sleeve structured MWCNT/PANI composite was prepared.•The optimum mass ratio of MWCNT/ANIranges between 1:3 and 1:1.•The π-π drive force was confirmed by spectroscopicmeans.•The polymerization time of 12∼24 hrs affords the highest conversion efficiency.•The DSSCs assembled with the MWCNTs/PANI CEs exhibit a comparable η(7.21%) as that with Pt CE (7.59%).

Axle-sleeve structured composite materials made with multi-walled carbon nanotubes (MWCNTs) and polyaniline (PANI) were prepared, characterized, and employed as cost-effective counter electrodes (CEs) in dye-sensitized solar cells (DSSCs). The composite was synthesized by co-polymerization of aniline with carboxylated MWCNTs by using ammonium persulfate in the acidic medium. Thin films of MWCNTs/PANI were prepared via a spin coating technique followed by thermal treatment in N2 atmosphere. The micro-structure of the composite was studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) linked with energy dispersive spectroscopy (EDS). The coating layer of PANI on the MWCNTs and new-formed chemical bonds between MWCNTs and PANI was studied by UV-Vis absorption, X-ray photoelectron spectroscopy (XPS), Raman and FT-IR spectroscopic means. The effect of the multiple-level porosity or the axle-sleeve structures in the composite of MWCNTs/PANI on the electro-catalytic activity was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopic (EIS) analysis. The DSSCs assembled with MWCNTs/PANI as CEs exhibit a comparable energy conversion efficiency (η) of 7.21% as compared to that of a DSSC consisting of a screen-printed Pt CE (η = 7.59%). These promising results propose a potential application of MWCNTs/PANI in cost-effective DSSCs.

Graphical abstractAxle-sleeve structured composite materials made with carbon nanotubes and polyaniline were prepared via a co-polymerization strategy. The composite materials were employed as cost-effective counter electrode modifier in dye-sensitized solar cells which demonstrate a comparable photo-to-electron conversion efficiency as the Pt catalyst.Figure optionsDownload full-size imageDownload as PowerPoint slide