Stabilization of n-type semiconductors to photoanodic dissolution: II–VI and III–V compound semiconductors and recent results for n-type silicon

Semiconductor-based photoelectrochemical cells for the conversion of light to electricity are described. Such cells consist of a semiconductor photoelectrode, a counterelectrode, and an electrolyte solution containing electroactive species. Results for cells employing certain n-type II–VI (CdS, CdSe, CdTe) and III–V (GaP, GaAs, InP) photoelectrodes in solutions of electroactive X2−/Xn2−(X=S, Se, Te) species are reviewed. The key fact is that for a number of photoelectrode /X2−/Xn2− combinations we find that photoanodic decomposition of the semiconductor is virtually totally suppressed, allowing the sustained conversion of light to electricity. Preliminary results for n-type Si photoelectrodes derivatized with electroactive ferrocene reagents are also outlined, and the associated photoelectrochemical activity of the surface species is compared to results for naked Si exposed to solutions of ferrocene.