High conductive and transparent thin films based on
carbon nanotube – poly(3,4-ethylene-dioxythiophene)-poly(styrene
sulfonate), PEDOT-PSS blends have been used to replace the conventional
indium tin oxide (ITO) as the hole collecting electrode in organic
photovoltaic cells. Using PEDOT:PSS as the host material, excellent
dispersion of functionalized single wall carbon nanotubes can be achieved
enhancing the polymer's conductivity, while maintaining its excellent
optical transparency. Photovoltaic cells with Poly(3-hexylthiophene), P3HT
and [6,6]-phenyl-C61 butyric acid methyl ester (PCBM as the
electron donor and acceptor on respectively on polymer-nanotube substrates
have been fabricated and characterized. A power conversion efficiency of
1.3%, with a fill factor of 0.4, an open-circuit voltage of 0.6 V and
a short-circuit current of 5.6 mA/cm2 under 100 mW/cm2 white
light illumination are reported. These values are close with the
reference cells made on ITO glass substrates with the same device
structure and fabrication process. The only drawback is on the fill factor
which is considerably smaller due to the high resistance of the
polymer-nanotube film. Nevertheless, the results indicate that the spin
casted polymer-nanotubes thin films are a low cost alternative to ITO for
organic electronics.