PHOTOELECTROCHEMICAL SOLAR-CELLS - PRESENT STATUS

This review focuses on the present status and emerging trends of photo electrochemical (PEC) solar cells. PEC cells are wet photovoltaic syst ems with vital advantages over their solid-state counterparts. The imp ortant operational principles, classification and a historical account of development of PEC solar cells have been dealt with. Some of the e arlier studied and recently discovered photoelectrode materials have b een outlined. To make an efficient and viable PEC solar cell, some of the feasible efficiency enhancement processes such as electrode surfac e modification, electrolyte modification, etc. have been described. Th e high efficiency PEC solar cell developed in our laboratory, i.e. n-W Se2/I-, I3-/Pt cell (eta approximately 17%) and some of the important and efficient photoelectrosynthetic solar cells where solar-to-chemica l energy conversion is possible have been discussed. Recent trends emb odying the development of new and efficient photoelectrode materials a nd semiconductor septum (SC-SEP) cells have been reported. The case of a recent novel PEC cell incorporating nanostructured TiO2 photoelectr ode overlaid with special dye (ruthenium trinuclear cyanide complex) a nd exhibiting efficiencies of 7% (under usual solar illumination) and 12% (in diffuse solar light), has also been outlined. It is suggested that further efforts to develop new and efficient photoelectrode mater ials, e.g. nanocrystalline versions of known photoelectrode materials and novel cell designs to eventually obtain high conversion efficiency and long-term stability should form one of the priority areas of the chemical routes for trapping solar energy.