Precisely tailoring the precursor solution for efficient AgBiS₂ solar cells

AgBiS₂ has been considered by researchers as a new-generation photovoltaic material because of its ideal bandgap, environment-friendliness and wide absorption range. Although it has shown great development potential in solar cell devices, due to the lack of systematic exploration and research on precursor solution chemistry, the performance of AgBiS₂ solar cells prepared by the precursor solution method lags behind those of colloidal solution-processed cells. Herein, we report a pre-nucleation strategy that involves controlling the precursor solution at the molecular level. The pre-nucleation strategy results in faster nucleation of the AgBiS₂ crystals during crystallization, resulting in AgBiS₂ thin films with larger grains, fewer defects and more homogeneous cation disorder. The improved quality of the AgBiS₂ thin films resulted in high-performance AgBiS₂ thin film solar cells with a J_SC of up to 30.9 mA cm⁻² and a record high PCE of 3.68%. This work provides a feasible method for the preparation of AgBiS₂ thin film solar cells based on the precursor solution.