Highly efficient and stable dye-sensitized solar cells based on nanographite/polypyrrole counter electrode

•Pt-free dye-sensitized solar cells.•The nanographite/PPy composite film showed high catalytic activity as well as Pt electrode.•The enhanced catalytic activity was attributed to increased active sites.•The DSSC based on the nanographite/PPy electrode showed a high photovoltaic performance.

Nanographite/polypyrrole (NG/PPy) composite film was successfully prepared via in situ polymerization on rigid fluorine-doped tin oxide substrate and served as counter electrode (CE) for dye-sensitized solar cells (DSSCs). The surface morphology and composition of the composite film were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectra and Fourier transform infrared spectroscopy (FTIR). The electrochemical performance of the NG/PPy electrode was evaluated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results of CV and EIS revealed that the NG/PPy electrode possessed excellent electrocatalytic activity for the reduction reaction of triiodide to iodide and low charge transfer resistance at the interface between electrolyte and CE, respectively. The DSSC assembled with the novel NG/PPy CE exhibited an enhanced power conversion efficiency of 7.40% under full sunlight illumination as comparing to that of the DSSC based on sputtered-Pt electrode. Thus, the NG/PPy CE could be premeditated as a promising alternative CE for low-cost and high- efficient DSSCs.

Graphical abstractMuch higher photovoltaic performance of dye-sensitized solar cell with nanographite/PPy counter electrode as well as that of Pt configuration device.Figure optionsDownload full-size imageDownload as PowerPoint slide