Copper Chalcopyrite Film Photocathodes for Direct Solar-Powered Water Splitting

摘要

In search of an efficient semiconductor material for direct photoelectrochemical (PEC) hydrogen production, chalcopyrite films in the Cu(In,Ga)Se{sub}2 system (CIGS) with bandgaps of 1.3-1.65eV have been evaluated. The films have been fabricated by 2-stage and 3-stage co-evaporation processes. Film samples have been fabricated into CIGS/CdS solar cells for evaluation of solid-state device properties, and into CIGS photocathodes for evaluation of the photoelectrochemical hydrogen-production characteristics. The PEC current-potential scans of the photocathodes in 0.5M sulfuric acid show photocurrents of 18-27mA/cm{sup}2 under simulated AM1.5 global light (100mA/cm{sup}2) at sufficient cathodic potential bias. In terms of fill factor of the photocurrent curves, electrodes with molybdenum back contact are superior to SnO{sub}2:F back contact because of better conductivity. The morphology as seen in scanning electron micrographs is unchanged after initial PEC testing in the cathodic regime, suggesting films are stable.