Direct synthesis of semiconductive AgBiS₂ NC inks toward high-efficiency, low-cost and environmental-friendly solar cells

Silver bismuth sulfide nanocrystals (AgBiS₂ NCs) embody a pioneering heavy-metal-free photovoltaic material renowned for its ultrahigh absorption coefficient, offering promising opportunities for advancing the field of ultra-thin and biocompatible solar cells. Currently, the fabrication of AgBiS₂ NC photovoltaic devices relies on hot-injection synthesis and subsequent tedious ligand exchange, leading to high production cost, complex processes and environmental pollution. Here, we developed a direct-synthesis (DS) method without ligand-exchange for AgBiS₂ NC semiconductive inks, significantly simplifying the material preparation and device fabrication processes. The synthesis cost of AgBiS₂ inks (17.0 $ g⁻¹) is over an order of magnitude lower than the traditional method (203.5–275.2 $ g⁻¹). Through optimizing synthesis and device structure, a champion power conversion efficiency of 9.32 % was achieved, aligning with the highest reported efficiency (9.17 %) based on ligand-exchanged methods. In addition, our DS-AgBiS₂ inks show excellent storage stability for over ten months. More importantly, the life cycle assessment (LCA) indicates drastically reduced energy consumption as well as environmental and human health impact for our strategy. The low-cost and scalable synthesis approach for AgBiS₂ NC semiconductive inks present a “greener” pathway for the commercial applications of NC optoelectronics.