Direct Solution Processed Ag(Bix,Sb1−x)S2 Films with Tunable Bandgap for Planar Heterojunction Solar Cells

Silver bismuth antimony sulfide (Ag(Bix,Sb1−x)S2, 0 ≤ x ≤ 1) is considered as a promising light‐harvesting material for solar cell applications because of its excellent stability, abundant element storage, and tunable bandgap. However, the method for depositing the Ag(Bix,Sb1−x)S2 film hasn't been developed, which hinders the investigation of the composition‐dependent photoelectric properties, such as bandgap, band position tunability, and photovoltaic characteristics. In order to apply Ag(Bix,Sb1−x)S2 in photovoltaics, the authors report a convenient solution method to prepare Ag(Bix,Sb1−x)S2 films with continuously tunable constituents through varying the ratio of Bi and Sb in the solution. The bandgaps of Ag(Bix,Sb1−x)S2 films can be turned from 1.70 to 1.22 eV through changing the Bi/Sb ratio. Moreover, for the first time, the authors confirm that Ag(Bix,Sb1−x)S2 can be applied in solar cell applications. Upon device optimizing, the device based on Ag(Bix,Sb1−x)S2 (x = 0.4) shows a champion power conversion efficiency of 2.70%. This research provides an effective method for fabricating Ag(Bix,Sb1−x)S2 films with regulating the bandgap and confirms the photovoltaic application of Ag(Bix,Sb1−x)S2.