Monoclinic AgSbS2 thin films for photovoltaic applications: Computation, growth and characterization approaches

Monoclinic silver antimony sulfide (AgSbS2) thin films have been studied based on computational, deposition, characterization, and photovoltaic device fabrication approaches. Computational tactics involved determination of the crystal structure as well as electronic band structure. In experimental approach, AgSbS2 thin films were synthesized by heating Sb2S3/Ag double layered precursor in which Ag was thermally evaporated on to chemically deposited Sb2S3 films. AgSbS2 thin film growth was studied by varying Ag layer thickness in the range of 10–110 nm for a given thickness of Sb2S3, in terms of crystal structure, morphology, elemental composition, and their photo-physical properties. X-ray diffraction analysis of the films showed formation of monoclinic AgSbS2 in correlation with the theoretically generated structure. The density functional calculations predicted an indirect optical transition with a bandgap of 1.77 eV, and this was evidenced in our experimental values in the range of 1.7–1.8 eV. The AgSbS2 thin films formed using different Ag thicknesses were incorporated to photovoltaic structures with superstrate configuration: glass/FTO/n-CdS/p-AgSbS2/C/Ag. The best device yield was Voc = 530 mV, Jsc = 5.5 mA/cm2, FF = 0.50 and ƞ = 1.5%, the highest efficiency ever reported using monoclinic AbSbS2 as absorber. [Display omitted] •Theoretical studies of crystal structure, band structure and density of states for monoclinic AgSbS2.•Monoclinic AgSbS2 thin films by heating Sb2S3/Ag layers by varying silver thickness.•The experimental bandgap value in correlation with the transitions predicted by theoretical band structure.•n-CdS/p-AgSbS2 solar cell giving Voc = 530 mV, Jsc = 5.5 mA/cm2, FF = 0.50 and ƞ = 1.5%.•The best efficiency ever reported for monoclinic AgSbS2 based single junction PV device.