Photosensitization of ITO and nanocrystalline TiO2 electrode with a hemicyanine derivative

The monochromophore (E)-N-Hexadecyl-4-(2-(4-diethylamino)phenyl)ethenyl) pyridinium stearate was synthesized. The LB film of the dye-modified ITO gives rise to cathodic photocurrent, while the dye-sensitized nanocrystalline TiO2 film generates anodic photocurrent. Having investigated some factors such as electron donor and acceptor, and bias voltage that may affect the magnitude of photocurrent and the direction of current flow, we proposed a mechanismic model for photocurrent generation. The quantum yield is about 0.2% for monolayer LB film-modified ITO electrode and 1.0% for the dye-sensitized nanocrystalline TiO2 film under irradiation of 469-nm light in 0.1 M KCl aqueous solution without applied potential. Under 100 mW/cm2 illumination of simulated solar light, the dye-sensitized nanocrystalline TiO2 film generated greater than 1 mA/cm2 of current density, which is comparatively high among the organic dyes.