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

Abstract

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.