Composite Films Based on Poly(3,4-ethylene dioxythiophene): Poly(styrene sulfonate) Conducting Polymer and TiC Nanoparticles as the Counter Electrodes for Flexible Dye-Sensitized Solar Cells

A composite film of poly(3,4-ethylene dioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) and titanium carbide nanoparticles (TiC-NPs) was deposited on an indium doped tin oxide-poly(ethylene naphthalate) (ITO-PEN) conducting plastic substrate by a doctor blade technique. This ITO-PEN substrate with the composite film was used as the flexible counter electrode (CE) for a plastic dye-sensitized solar cell (DSSC). Performances of the plastic DSSC with the platinum-free CEs containing PEDOT:PSS/TiC-NPs composite was investigated. A solar-to-electricity conversion efficiency (eta) of 6.50% was achieved for the pertinent DSSC with PEDOT:PSS/TiC-NPs composite, using commercial N719 dye, which exhibited comparable performance to that of a cell with a sputtered-Pt film on its CE (6.84%). The homogeneous nature of the composite film PEDOT:PSS/TiC-NPs, the uniform distribution of TiC-NPs in its PEDOT: PSS matrix, and the large electrochemical surface area of the composite film are seen to be the factors for the best performance of the pertinent DSSC. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to characterize the TiC-NPs. Scanning electron microscopy (SEM), atomic force microscopy (AFM), and energy dispersive X-ray spectroscopy (EDX) were used to characterize the films. The high efficiency of the cell with PEDOT:PSS/TiC-NPs is explained by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and incident photon-to-current conversion efficiency (IPCE) curves. (C) 2012 The Japan Society of Applied Physics