Cs<sub>2</sub>AgSbI<sub>6</sub> Nanocrystals: a New Air-Stable Iodide Double-Perovskite (Elpasolite) Semiconductor
Faris Horani, Daniel R. Gamelin
Abstract
Three-dimensional (3D) iodide double perovskites (elpasolites) are extremely rare due to inherent instability issues. Here, we report the discovery of an air-stable iodide elpasolite semiconductor in the form of nanocrystals with the composition Cs 2 AgSbI 6, synthesized via halide exchange from Cs 2 AgSbBr 6 nanocrystals. This composition, previously considered thermodynamically unstable based on computational predictions, shows a ∼1.8 eV optical gap with near-infrared photoluminescence. The nanocrystals are stable in air up to at least 140 °C. As one of only a few known examples of intermediate-bandgap 3D iodide double perovskites, Cs 2 AgSbI 6 represents a promising platform for further development of this family of materials as well as for fundamental and optoelectronic investigations.