AgBiSe 2 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 (AgBiSe 2 ) is used as the prototyping material, as well as silver bismuth sulfide (AgBiS 2 ) and alloyed silver bismuth sulfide-selenide (AgBiS x Se y ) to show the bandgap tunability of the obtained nanocrystals by utilizing a simple mixed anion precursor approach. A preliminary solar cell made of colloidal AgBiSe 2 nanocrystals synthesized via the proposed ambient-condition method yields a power conversion efficiency up to 2.6%, which is the first colloidal AgBiSe 2 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.