Mid-Infrared Emission from Tm 3+ -Doped Perovskite Fluoride Glasses Enabled by Host Structure Engineering and Gas Sensing Applications

Rare-earth perovskites have been widely investigated for their flexible optical properties and promising prospects in mid-infrared (MIR) applications. However, the structure-dependent luminescence behavior of rare-earth ions is still not fully understood, making emission regulation challenging. In this work, Tm 3+ was introduced into three structural types of perovskites – Cs 2 ZnCl 4, CsPbCl 3, and CsPbBr 3 – and stabilized within a ZBLAN (ZrF 4 –BaF 2 –LaF 3 –AlF 3 –NaF) fluoride glass matrix. Under 793 nm excitation, Cs 2 Zn 0.85 Tm 0.15 Cl 4 -ZBLAN and CsPb 0.85 Tm 0.15 Cl 3 -ZBLAN exhibited enhanced emission at 1.47 μm, while CsPb 0.85 Tm 0.15 Br 3 -ZBLAN showed stronger enhancement at 1.67 μm, with additional emissions at 2.37 and 3.46 μm. These results demonstrate that the host crystal structure has a significant influence on the mid-infrared emission performance of Tm 3+ ions. XRD and XPS analysis revealed the influence of lattice distortion, and a prototype HCl gas sensor highlighted the potential of Tm 3+ perovskite fluoride glasses as broadband MIR emitters for practical sensing applications.