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.