Photovoltage and stability of an n-type silicon semiconductor coated with metal or metal-free phthalocyanine thin films in aqueous redox solutions

Abstract

An n-type silicon (n-Si) semiconductor coated with an evaporated thin film of metal phthalocyanine (MPc) or metal-free phthalocyanine (H/sub 2/Pc) worked as a fairly stable photoanode in aqueous redox solutions. The photovoltage observed for a photocell, (n-Si/CuPc/Fe/sup 3 +//Fe/sup 2 +/ aqueous solution (pH 4.2) /Pt), was 0.50 V, only slightly less than that for a p-n junction Si photocell (approx. 0.6 V). The action spectrum was similar to that of a bare n-Si electrode, except for a depression caused by photoabsorption by the CuPc film in the red region. The above wet photocell has current-voltage characteristics better than those for a solid photocell, (n-Si/CuPc/Pd).