Novel cryogenic dual-emission mechanism of lead-free double perovskite Cs 2 AgInCl 6 and using SiO 2 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 .
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