Fabrication and Characterization of Cu 3 SbS 4 Solar Cell with Cd-free Buffer

We have grown famatinite Cu 3 SbS 4 films by using sulfurization of Cu/Sb stack film. Sulfurization at 500 °C produced famatinite Cu 3 SbS 4 phase, while 400 °C and 450 °C sulfurization exhibited unreacted and mixed phases. The fabricated Cu 3 SbS 4 film showed S-deficiency, and secondary phase of Cu 12 Sb 4 S 13 . The secondary phase was confirmed by X-ray diffraction, Raman spectroscopy, photoluminescence and external quantum efficiency measurements. We have also fabricated solar cell in substrate type structure, ITO/ZnO/(Zn,Sn)O/Cu 3 SbS 4 /Mo/glass, where Cu 3 SbS 4 was used as a absorber layer and (Zn,Sn)O was employed as a Cd-free buffer. Our best cell showed power conversion efficiency of 0.198%. Characterization results of Cu 3 SbS 4 absorber indicates deep defect (due to S-deficiency) and low shunt resistance (due to Cu 12 Sb 4 S 13 phase). Thus in order to improve the cell efficiency, it is required to grow high quality Cu 3 SbS 4 film with no S-deficiency and no secondary phase.