Visible to near-infrared light harvesting in Ag2S nanoparticles/ZnO nanowire array photoanodes.

Pronounced absorption in the visible-NIR range of 400-1300 nm is demonstrated in the Ag(2)S nanoparticles (NPs)/ZnO nanowire (NW) array. ZnO NW arrays are grown on indium tin oxide substrates using chemical bath deposition. The Ag(2)S NPs are sequentially formed on the ZnO NWs through sonochemical synthesis. Structural characterizations indicate the slight deconstruction of surface of ZnO NWs during Ag(2)S NPs formation. By employing polysulfide electrolyte, short-circuit current (J(sc)), open-circuit voltage and therefore the efficiency of the Ag(2)S NP-sensitized ZnO NW solar cell are improved with increasing the initial sulfur concentration in the sulfur-polysulfide electrolyte. The Ag(2)S NP-sensitized ZnO NW solar cell shows a conversion efficiency of 0.49% with a superior J(sc) of ~13.7 mA cm(-2) under AM 1.5 illumination at 100 mW cm(-2). Incident photon conversion efficiency measurements reveal that Ag(2)S NPs contribute to 33.4% and 65.2% of J(sc) in the wavelength ranges of 400-700 nm and 700-1300 nm, respectively. This journal is © The Royal Society of Chemistry 2012