Efficient solar energy conversion with CuInS2

The high absorptivity associated with a direct energy gap in the optimum range for solar-energy conversion makes CuInS2 a particularly promising material for efficient solar-energy conversion1. Achieved solar-to-electrical conversion efficiencies have been limited to ∼6% (refs 2–8). We report here a new heterogeneous poly crystalline n-CuInS2 based semiconductor which has yielded conversion efficiencies of 9.7% in an electrochemical cell. The high photoactivity is also evident in a Schottky barrier solar cell configuration. The origin of the improved efficiency is attributed to impurity scavenging by In spheres resulting from a modified vapour/liquid/solid (VLS) growth process9–11 and the influence of the acidic iodine iodide electrolyte on the cell performances.