CuSbS thin films and solar cells produced from Cu/Sb/Cu stacks via sulfurization.

Phase-pure crystalline chalcostibite (CuSbS) thin films were prepared by depositing Cu/Sb/Cu metal stacks using a thermal evaporation method, followed by sulfurization at 400  C and 430  C for different durations. The investigation revealed the formation of a dominant orthorhombic CuSbS phase accompanied by a minor SbS phase in the film stacks sulfurized at 400  C for 10-60 min. Extending the reaction time to 90 min triggered a decrease in the SbS phase and the emergence of an additional famatinite (CuSbS) phase alongside the dominant CuSbS phase. Sulfurization of the film stack at 430  C for 10 min similarly produced a CuSbS secondary phase. When sulfurization was maintained beyond 30 min at 430  C, it resulted in phase-pure CuSbS films, characterized by a crystalline grain size of 25.9 nm, direct bandgap of 1.41 eV, and hole mobility ranging from 0.6-1.0 cmVs. Thin film solar cells fabricated using the CuSbS absorbers grown at 430  C for 30-90 min displayed exceptional device efficiency due to the formation of phase-pure and highly crystalline films. Specifically, solar cells fabricated using the CuSbS absorber sulfurized for 60 min demonstrated a peak device efficiency of 2.2%, featuring an open-circuit voltage of 546.6 mV, short-circuit current density of 12.8 mA/cm, and a fill factor of 31.3%. This study provides a reference for preparing highly crystalline CuSbS thin films for efficient solar cells.