Photo-intercalation: Possible application in solar energy devices

Theoretical considerations and preliminary photo-electrochemical experiments with ZrSe₂ indicate the possibility of converting and simultaneously storing solar energy by means of light driven electrochemical reactions producing intercalation compounds of layer-type semiconducting material. A precondition is that the intercalated compound maintains a semiconducting behaviour and that its ionic properties complement in a favourable way. Promising substrates were identified inp-type zirconium-and hafniumdichalcogenides, but also TiS₂ would be useful if it could be madep-conducting. Solar cells based on photo-intercalation — if they could be developed for practical use — would not only be simple sandwich ofp-conducting layer-type semiconductor (e.g. ZrS₂)/ionic conductor (wet or solid)/metal of intercalating species (e.g. Cu)], but also more convenient to use in irregular sunlight than conventional devices. Some thermodynamic properties and attainable efficiencies of this new type of solar cell are discussed as well as difficulties which would have to be surmounted.