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/N-2 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 degrees 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/cm(2) short-circuit current, and 6.2% efficiency.