Halide-ligand-dependent Performance of AgBiS2 Nanocrystal/ZnO Heterojunction Solar Cells

The carrier transport properties of solar cells fabricated with colloidal AgBiS2 nanocrystals (NCs) are affected by the type of ligands adsorbed on the nanoparticle surface, the coverage, and the coordination state. We focus on halide ions (F-1, Cl-1, Br-1, and I-1) to passivate the surface of AgBiS2 NCs and investigate their adsorption behavior using X-ray photoelectron spectroscopy (XPS) in this study. The adsorption strength of ligands was a useful figure of merit that could explain the correlation between the ligand type and solar cell performance. The Br ligand achieved the best NC passivation among the four halide ligands. Therefore, the cell with a Br ligand shows the highest solar cell performance.