Back contact nature effect on the CZTS/ZnS based heterojunction

International audienceThis work contributes to the discussion on the influence of theback contact on the electrical properties of Cu2ZnSnS4 (CZTS)-basedsolar cells. Devices with noble metals back contact (Au, Ag and Pt)such as FTO/ZnS/CZTS/Au, FTO/ZnS/CZTS/Pt and FTO/ZnS/CZTS/Ag wereinvestigated by means of the current voltage characteristic in thedark (FTO = fluorine-doped tin oxide). The originality of this workis that all active layers (absorbing and buffer layers) aredeposited by the same system using spray pyrolysis technique. Themetallic back contacts are sputter deposited. X-ray diffraction(XRD) and UV–visible spectrophotometry were used to investigate themain structural and optical properties of different layersconstituting the solar cell. The electrical characterizationachieved by I–V characteristic proves that all synthesizedheterojunctions exhibit a rectifying behavior. Furthermore, theideality factors of Au, Pt and Ag back contacts were estimated to1.6, 2.4 and 2.8, respectively. The lower saturation current andseries resistance are measured in the heterojunction using Au as aback contact. From this study, it is shown that Au back contactcould be an alternative of Mo in CZTS-based solar cell prepared byspray pyrolysis