TERNARY CHALCOGENIDE-BASED PHOTOELECTROCHEMICAL CELLS .4. FURTHER CHARACTERIZATION OF THE NORMAL-CULNS2 AND NORMAL-CULNSE2 AQUEOUS POLYSULFIDE SYSTEMS

The photoelectrochemistry of n-CuInS//2 and CuInSe//2 in polysulfide electrolyte is studied with particular emphasis on the pretreatments of the electrodes and on their output stability. The use of Cd doping, (photoelectro)chemical etching, and mild air oxidation all were found to improve electrode performance. The effect of air oxidation was reproducible only for the diselenide, where it improved the fill factor and, because of a negative shift of the flatband potential, the open-circuit voltage. Optimized cells showed, at elevated temperatures, conversion efficiencies around 5 and 7. 5% for the sulfide and selenide, respectively.