Characterization of a CZTS thin film solar cell grown by sputtering method

•6.2% CZTS/CdS solar cell without AR coating.•QE modeling shows less than half the thickness of the CZTS layer contributes to photocurrent.•Detailed characterization of the CZTS cell properties.

We report the performance of Cu2ZnSnS4 (CZTS) thin film solar cell that showed efficiency in the range of 6.2% without an anti-reflection coating. Initially, the CZTS precursor film was co-sputtered using three different targets; copper (Cu), tin sulfide (SnS) and zinc sulfide (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 sulfurized in a H2S/N2 environment at 525 °C, which re-crystalized the film with grain sizes in the range of 1 μm. Cadmium sulfide (CdS) was used as the n-type layer. Current–voltage (I–V), quantum efficiency (QE) and capacitance–voltage (C–V) measurements were used to characterize the cell device. The modeling and analysis of QE and CV data showed that a significant portion of the CZTS layer did not contribute to the photo-generation. Optimizing CZTS phase purity, improving QE in the broader wavelength region, and increasing minority carrier lifetime are necessary steps to further improve CZTS device performance.