Effect of internal surface area on the performance of ZnO∕In2S3∕CuSCN solar cells with extremely thin absorber

Solar cells with an extremely thin light absorber were realized by wet chemical preparation on arrays of ZnO nanorods. The absorber consisted of an ${\mathrm{In}}_2{\mathrm{S}}_3$ layer ($\sim 20\mathrm{nm}$ thickness) and its interface region with a transparent CuSCN hole conductor. By changing the length of the nanorods $(0–3.3\mu \mathrm{m})$ and keeping the ${\mathrm{In}}_2{\mathrm{S}}_3$ layer thickness constant at $\sim 20\mathrm{nm}$ , the short circuit current increased from about $2–10\mathrm{mA}∕{\mathrm{cm}}^2$ . A marked increase of the external quantum efficiency at longer wavelengths is attributed to light scattering and a solar energy conversion efficiency of 2.5% has been demonstrated.