Enhanced Infrared Emission from Rare-Earth Double Perovskite Embedded in Fluoride Glass with Different B-Site Cation Structures for NO Sensing in a Hydrogen Stream.

Rare-earth halide perovskites can lead to a distinctive infrared luminescence. However, achieving tunable infrared luminescence presents significant challenges. The leptons of their f-f ubiquitous forbidden ring influence the energy level splitting, and the substitution of atoms in perovskite by rare-earth ions also distorts the crystal structure. The research on achieving tunable mid-infrared emission by altering the crystal structure of rare-earth perovskites is limited. The crystal structure can be modified by changing the matrix B-site cation for a series of CsMInHoCl-ZBLAY (M = Na and Ag) rare-earth perovskites coated with a glass matrix that have been prepared. On this basis, we revealed the local electronic structure of CsMInCl (M = Na and Ag) perovskites and proposed an effective charge transfer strategy to achieve an efficient infrared emission of Ho ions at 1.2 and 2.87 μm. The contribution of Na s and Na p is minor in CsNaInHoCl, which leads to poor interactions between Na and Cl and promotes charge transfer of Ho-Cl in the [HoCl] octahedron. The charge transfer mechanism of CsNaInCl:Ho-Cl is validated by executing density functional theory calculations. Furthermore, a device that identifies NO gas levels in hydrogen energy was built using the CsNaInHoCl-ZBLAY sample. These findings provide a new perspective on how to achieve effective infrared emission.