AgBiSe₂ Colloidal Nanocrystals for Use in Solar Cells

Metal selenide nanocrystals have attracted attention as promising materials in photovoltaics and thermoelectrics. However, the expensive and labor-intensive synthesis methods utilized for the production of these nanomaterials have impeded their widespread utilization. The need for an air-free environment and high synthesis temperature for crystal nucleation and growth leads as the major factors contributing to the cost of synthesis. In this work, we present a synthesis method for metal selenide nanocrystals at room temperature under ambient conditions that is enabled by a cost-effective selenium precursor. Thanks to its relative abundance and low toxicity, ternary silver bismuth selenide (AgBiSe2) is used as the prototyping material, as well as silver bismuth sulfide (AgBiS2) and alloyed silver bismuth sulfide-selenide (AgBiSxSey) to show the bandgap tunability of the obtained nanocrystals by utilizing a simple mixed anion precursor approach. A preliminary solar cell made of colloidal AgBiSe2 nanocrystals synthesized via the proposed ambient-condition method yields a power conversion efficiency up to 2.6%, which is the first colloidal AgBiSe2 nanocrystal solar cell reported in the literature to the best of the author’s knowledge. This synthesis route is expected to pave the way for low-cost, environmentally friendly, and solution-processed photovoltaics.