Enhanced photoelectrochemical solar-energy conversion by gallium arsenide surface modification

In the n-GaAs/Se=–Se=x–OH−/C liquid junction solar cell, modification of the semiconductor surface by incorporation of ruthenium increases both the fill factor and the open-circuit voltage and improves the reproducibility of performance. The power conversion efficiency of the modified cell is 12% under ∼100 mW/cm2 sunlight. Surface metal atoms or ions are shown to alter GaAs cell behavior widely; Ru represents a case for which the effect on cell performance is both positive and persisting.