Vacancy-Catalyzed Cation Homogenization for High-Performance AgBiS₂ Nanocrystal Solar Cells

Environmentally friendly silver bismuth sulfide (AgBiS2) nanocrystals (NCs) are promising solution-processed absorbers for photovoltaic applications. Cation disorder nonhomogeneity has been considered as a prevalent obstacle, significantly impacting the optoelectronic properties of AgBiS2 films. In this work, we developed a vacancy-assisted strategy to mitigate the energy barriers for the cation homogenization process in AgBiS2 NC films. Chloride ions are introduced to induce surface vacancies, leading to improved cation homogeneity and enhanced absorption under low-temperature annealing. The resultant AgBiS2 NC solar cells exhibited a power conversion efficiency (PCE) over 10%, the highest to date from a solid-state ligand-exchange method. Our strategy not only enables high-quality AgBiS2 NC films but also provides an approach for engineering cation disorder in multinary materials.