Colloidal AgBiSe2 and AgBi(S1-x Se x )2 Nanocrystals with Composition-Tunable Properties Based on Bis(acyl) Selenide Precursors.

Heavy-metal-free metal selenide nanocrystals have attracted great interest as low-cost, environmentally friendly, and solution-processable materials for future optoelectronics and thermoelectrics. Despite the widespread prospects of these materials, their preparation and processing remain a challenge, as the fabrication is laborious and may require harsh environments and toxic chemicals, and, more importantly, most widely used selenium precursors for the synthesis of colloidal NCs are not only toxic and expensive but also highly unstable, which makes them extremely difficult to handle and leads to unreproducible results. In this work, we present a facile synthetic approach for obtaining colloidally stable ternary silver bismuth selenide (AgBiSe2) and quaternary silver bismuth sulfide selenide (AgBi-(S1-x Se x )2) nanocrystals by utilizing bis-(acyl) selenides as an alternative precursor in the hot-injection synthesis method. The employed bis-(acyl) selenide precursors are stable under ambient conditions, easily processable, and allow great composition control on the anion side and, consequently, band gap fine-tuning in the case of AgBi-(S1-x Se x )2 nanocrystals, making them highly attractive for solution-processed optoelectronic devices.