Characterization and electrical property of the Cu-deficient Cu2ZnSn(S,Se)4 bulks at different sulfur contents

Cu-deficient Cu2ZnSn(SxSe1−x)4 (CZTSSe) pellets were fabricated by reactive liquid-phase sintering at 600 °C with two types of sintering aids of Sb2S3 and Te and two types of compensation discs of CuSe2 and SnSe2 for selenization and CuS and SnSe2 for sulfo-selenization and sulfurization. Selenides of Cu2Se, ZnSe, SnSe2, and SnSe and sulfides of CuS, ZnS, and SnS were the constituent powders. Comprehensive characterizations of the CZTSSe pellets at different S/(S + Se) ratios were performed. The compositions of Cu, Zn, Sn, and the sum of all anionic elements did not change with the sulfur content. No second phases were detected. The highest mobility of 3.5 cm2 V−1 s−1 was obtained for CZTSSe at x = 0.5. Electrical property of polycrystalline CZTSSe is important for making thin-film solar cells, but systematic investigation was limited. We systematically measured the electrical property of CZTSSe bulks and found that carrier mobility was an important factor in selecting the absorber materials.

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► We developed a sintering procedure for Cu2ZnSn(S,Se)4 or CZTSSe bulks.
► Our CZTSSe bulks changed the anionic ratio while kept cationic ratios constant.
► Electrical properties of CZTSSe are reported to change with the S ratio.
► Electrical property of CZTSSe is important to know the absorber of solar cells.