Copper sulfide and its indium/gallium based ternaries have proven successful in high efficiency photovoltaics. Meanwhile, the less explored antimony based ternaries have similar electro-optical properties. In this work, we report on a high throughput exploration of the Cu-Sb-S phase space, electrical and optical properties of two ternaries within this space, and some initial material engineering and photoelectrochemical characterization on the CuSbS2 phase.<br/><br/>Combinatorial libraries exploring the chemical phase space were created by RF magnetron co-sputtering of Cu2S and Sb2S3 targets. Stationary substrates placed equidistant from each target allowed precise control of the chemical potential from right to left (via target power ratios). Spatially resolved tools were then used to parse the unique composition (XRF), structure (XRD) conductivity (4 point probe), and optical absorption (UV/Vis/NIR) of several points of one library (substrate). Of the four ternaries within the Cu-Sb-S phase space, Cu12Sb4S13 and CuSbS2 were successfully synthesized via this methodology. Cu12SbS13 was found to be a degenerate p-type semiconductor, the large amount of holes likely resulting from the disordered structure containing many Cu vacancies. CuSbS2, on the other hand, had more ideal electrical and optical properties, prompting further investigation.<br/><br/>The large difference in vapor pressure between Sb2S3 (high) and Cu2S (low) was exploited to deposit uniform, phase pure thin films of CuSbS2 with tunable carrier concentration. Growth temperatures above 350C kept Sb2S3 in the vapor phase, and carrier concentration in these films was found to be dependent the flux of Sb2S3, (similar to partial pressure dependence in oxide growth), or on the growth temperature (above the 350C threshold). Finally, photoelectrochemical measurements were taken on the resulting CuSbS2 thin films, producing small photocurrents (&lt;1.0mA/cm2) under AM1.5G illumination.

Antimony based copper sulfide ternaries as candidate thin film photovoltaic absorber materials

249th National Meeting (2015)

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