Speaker
Description
Halide perovskites based on the ABX3 structure have recently gained significant attention for emerging optoelectronic applications, including low-dimensional phases, double perovskites (A2BB’X6), and vacancy-ordered derivatives (A2BX6) [1]. In this context, vacancy-ordered double perovskites (VO-PVSKs) offer an alternative by replacing lead with high-Z elements, which are potentially less toxic while still preserving strong X-ray absorption properties. Their fully inorganic composition suggests improved resilience under high-energy radiation compared to hybrid halide perovskites, and their A2BX6 framework provides wide compositional flexibility, allowing access to a variety of tetravalent B-site cations.
In this work, we report a scalable wet mechanochemical route for the preparation of vacancy-ordered halide perovskites as a platform for compositional screening in systems based on Hf4+, Zr4+, and Te4+ cations. Across these compositions, broadband self-trapped exciton (STE) emission with large Stokes shifts is observed. Notably, binary and ternary mixtures show an enhanced yellow emission associated with Te4+ composition, suggesting the presence of an energy cascade process between different octahedral environments. We used pair distribution function (PDF) and Raman spectroscopy to study the local order of these compositions, indicating locally complex structures that may be relevant for radiation tolerance through high-entropy mixing. In situ X-ray total scattering experiments reveal a stable structural response up to ~300 ºC, while radioluminescence measurements under synchrotron X-ray excitation, as well as electron and alpha particle irradiation, confirm efficient emission under ionising radiation. Under continuous synchrotron X-ray exposure, the radioluminescence signal retains ~63% of its initial intensity up to doses of ~5kGy, corresponding to approximately 500k CT scans. These results point towards an accessible materials platform for emerging detection applications, including ion detection and space technologies.
References:
[1] T. Wang et al., Advances in Metal Halide Perovskite Scintillators for X-Ray Detection,Nano-Micro Lett., 17, 275, 2025, doi: 10.1007/s40820-025-01772-7.
[2] S. Fernández-Muñoz et al., Mechanochemical synthesis of B-site cation mixed vacancy-ordered chloride perovskites with enhanced stability, in preparation.