Novel cryogenic dual-emission mechanism of lead-free double perovskite Cs2AgInCl6 and using SiO2 to enhance their photoluminescence and photostability

Lead halide perovskite have attracted world-wide attention regarding their serious hazards on ecological environment and human health. To improve both the emission intensity and stability of Cs 2 AgInCl 6 , this study explores using SiO 2 to structurally adjust Cs 2 AgInCl 6 . Note that including SiO 2 changed the growth style and crystal morphology of Cs 2 AgInCl 6 from an octahedron to a truncated octahedron. After structural adjustment, the unit cells scattered, and the absorption limit broke. Moreover, SiO 2 was demonstrated to passivate the material’s surface to form an anti-oxidation protective layer. Consequently, the photoluminescence emission intensity increased by 181.5% and the stability of Cs 2 AgInCl 6 improved by 83.11%. This work provides a methodology and reference for future improvements to the luminescence of Cs 2 AgInCl 6 . Furthermore, a novel double-emission phenomenon ( λ ex = 365 nm: λ em ≈ 580 nm; λ ex = 325 nm: λ em ≈ 505 nm) of Cs 2 AgInCl 6 at cryogenic temperatures (20 K) was discovered; this phenomenon explains the shoulder emission problem of 400–450 nm at room temperature and clarifies the luminescence mechanism of Cs 2 AgInCl 6 .