Environmentally Friendly AgBiS₂ Nanocrystal Inks for Efficient Solar Cells Employing Green Solvent Processing

Silver bismuth sulfide nanocrystals (AgBiS₂ NCs) are emerging absorber materials for low-cost solar cells, owing to their solution-processability, environmentally friendliness, earth abundance, and high absorption coefficients. When it comes to green manufacturing technologies, besides the semiconductor materials, solvents play an equally important role. Here, solution-phase ligand-exchanged (SPLE) AgBiS₂ nanocrystal inks employing 3-mercaptopropionic (MPA) in methanol as a ligand solution are introduced. The resultant MPA capped AgBiS₂ nanocrystals can be fully dissolved in water, forming completely environmentally friendly nanocrystal inks. These nanocrystal inks allow the fabrication of fully green-processed photovoltaic devices with a power conversion efficiency up to 7.3%. This method not only demonstrates the potential of solution-phase ligand-exchanged AgBiS₂ nanocrystal inks, but also paves a path toward fully green-processed nanocrystal devices.