Characteristics of Photoelectrochemical Cells with ITO/p-Si Heterojunction Photoelectrodes Coated with Conducting Polymers

The Indium Tin Oxide (ITO)/p-Si heterojunction electrode was coated with polyaniline and its derivatives in order to improve the durability of photoefectrochemical (PEC) cells composed of ITO/p-Si electrode. ITO (containing 5 wt% SnO₂) was evaporated by an electron beam evaporator onto Si substrate. Conducting polymers were prepared by galvanostatic eleetropolymerization on ITO/p-Si at 10 μA.cm^-2, A 500 W Xenon lamp with an infrared filter was used for illumination. Although the quantum yield and the energy conversion efficiency of the PEC cell using the polymer-coated electrode were reduced by its higher resistance and photoabsorption of the polymer itself. However, the stability of the PEC cell was greatly improved. Particularly, the photdcurrent of the PEC composed of ITO/p-Si coated with polyaniline was found to be less than 20% degradation of the initial current value after 100 h photoirradiation.