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Abstract

To obtain an efficiency of about 10% in photoelectrochemical solar cells, the pairing of semiconductor material for the working electrode and composition of the electrolyte liquid is of critical importance. The semiconductor material therefore should not be too expensive, and should have a short absorption length for light and be resistant to photocorrosion. Further, a non-toxic electrolyte should be employed permitting operation even without a hermetic seal. The photoelectrochemical solar cell of the invention utilizes a CuInSe.sub.2 or CuInS.sub.2 in a ternary compound, for the semiconductor material, which is used with an iodine-iodide solution as an electrolyte. In a method of fabricating a substrate for such a cell, a surface film is produced on a single-crystal or polycrystalline semiconductor material, particularly CuInSe.sub.2, by immersing the semiconductor material after an etching and rinsing process into the electrolyte solution and simultaneously exposing it to light and polarizing it cyclically between two potential limits. Upon repeating this procedure several times, the material is exposed to light at the operating point for a longer time. The film thereby produced yields a p-n junction at the boundary layer. The advantage is a very high potential for an efficient solar energy conversion and the growth of the heterostructure can be controlled.

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First Claim