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

摘要

We report the performance of Cu_2ZnSnS_4 (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 H_2S/N_2 environment at 525 ℃, 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.