Functionalization of aligned carbon nanotubes used as counter electrode for dye-sensitized solar cells

Carbon nanotubes (CNTs) have been involved into the counter electrodes of dye-sensitized solar cells (DSSCs) to utilize its low cost and considerable electrical conductivity. However, the dispersion of CNTs needs to be improved because the aggregate of CNTs harms the performance of counter electrodes on DSSCs. In this work, aligned carbon nanotubes (ACNTs) were functionalized by adding poly (3,4-ethylenedioxythiophene)/poly(styrenesulfonic acid) (PEDOT:PSS), polyethylene glycol octylphenol ether (Triton X-100) and the blends of these two substances, respectively. The analysis results from Fourier transform infrared spectrometer (FTIR), x-ray diffraction (XRD), Raman, Thermogravimetric analysis (TGA) thermograph and x-ray photoelectron spectroscopy (XPS) analysis indicated that ACNTs were functionalized effectively. Then the ACNTs, Triton X-100/ACNTs, PEDOT: PSS/ACNTs and Triton X-100/PEDOT: PSS/ACNTs were employed as the counter electrode of DSSCs. The electrochemical activity of these counter electrodes and the photovoltaic properties of the DSSCs were detected. DSSCs with PEDOT: PSS/ACNTs counter electrode showed the best photoelectric conversion efficiency (PCE) of 3.85%, it is due to the PEDOT: PSS/ACNTs possessed remarkable electrochemical property and low value of Rct.