Enhancement of efficiency in Cu2ZnSnS4 (CZTS) solar cells grown by sputtering

We report the cell performance of Cu₂ZnSnS₄ (CZTS) thin film solar cell that showed efficiency in the range of 6 to 7 %. The absorber layer was grown by magnetron sputtering followed by annealing in a H₂S/N₂ environment. Initially, the CZTS film was co-sputtered with three different targets; copper (Cu), tin sulphide (SnS) and zinc sulphide (ZnS). The Cu target was subjected to DC power and RF power was used for the SnS and ZnS targets. The as-grown CZTS film was sulphurized in H₂S environment at around 510°C, which re-crystalized the film with larger grains. The quantum efficiency measurement showed internal quantum efficiency as high as 80% around 600 nm wavelength. A typical cell showed 610 mV open circuit voltage, 16 mA/cm² short-circuit current, and 6.2% efficiency.