Halide Mixing and Phase Segregation in Cs₂AgBiX₆ (X = Cl, Br, and I) Double Perovskites from Cesium-133 Solid-State NMR and Optical Spectroscopy.

ABSTRACT: All-inorganic double perovskites (elpasolites) are a promising potential alternatives to lead halide perovskites in optoelectronic applications. Although halide mixing is a well-established strategy for band gap tuning, little is known about halide mixing and phase segregation phenomena in double perovskites. Here, we synthesize a wide range of single- and mixed-halide Cs₂AgBiX₆ (X = Cl, Br, and I) double perovskites using mechanosynthesis and probe their atomic-level microstructure using ¹³³Cs solid-state MAS NMR. We show that mixed Cl/Br materials form pure phases for any Cl/Br ratio while Cl/I and Br/I mixing is only possible within a narrow range of halide ratios (<3 mol % I) and leads to a complex mixture of products for higher ratios. We characterize

SUBMITTER: Kubicki DJ 

PROVIDER: S-EPMC7558408 | biostudies-literature | 2020 Oct

REPOSITORIES: biostudies-literature