Chemical modification of n-GaAs electrodes with Os³⁺ gives a 15% efficient solar cell

Abstract

The minimization of interfacial recombination losses is a key factor in the operation of any semiconductor-based solar-energy-conversion device, including solid-state junctions, semiconductor/liquid junctions and colloidal suspensions of semiconductors. A frequently cited advantage of semiconductor/liquid junctions is the ability to manipulate surface recombination rates by chemical reactions^1–7. A notable example is the improvement in current–voltage properties of n-GaAs photoanodes which have been exposed to aqueous solutions of Ru³⁺ ions^8–10. Here we report new surface-modification procedures for GaAs which have produced the most efficient photoelectrochemical cell reported to date. We also report experiments which indicate that the current–voltage improvements in this system are accompanied by increased interfacial hole transfer rates at the GaAs/liquid interface.