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

Abstract

Pronounced absorption in the visible-NIR range of 400–1300 nm is demonstrated in the Ag₂S nanoparticles (NPs)/ZnO nanowire (NW) array. ZnO NW arrays are grown on indium tin oxide substrates using chemical bath deposition. The Ag₂S NPs are sequentially formed on the ZnO NWs through sonochemical synthesis. Structural characterizations indicate the slight deconstruction of surface of ZnO NWs during Ag₂S NPs formation. By employing polysulfide electrolyte, short-circuit current (J_sc), open-circuit voltage and therefore the efficiency of the Ag₂S NP-sensitized ZnO NW solar cell are improved with increasing the initial sulfur concentration in the sulfur–polysulfide electrolyte. The Ag₂S 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 Ag₂S NPs contribute to 33.4% and 65.2% of J_sc in the wavelength ranges of 400–700 nm and 700–1300 nm, respectively.