Bright Green-Emitting All-Inorganic Terbium Halide Double Perovskite Nanocrystals for Low-Dose X-ray Imaging

Inorganic halide double perovskite (DP) nanocrystals (NCs) have attracted great attention because of their nontoxicity, mild reaction conditions, good stability, and excellent optical and optoelectronic properties. Herein, we prepare the inorganic terbium halide DP Cs₂BTbCl₆ (B = Na or Ag) NCs with bright green photoluminescence (PL) emission. The Na-Tb-based DP NCs exhibit better PL properties compared with the Ag-Tb-based DP NCs, which is due to Cs₂NaTbCl₆ NCs having a more localized charge carrier distribution on the [TbCl₆]^3- octahedron. The incorporation of Sb³⁺ dopant in Cs₂NaTbCl₆ NCs can construct a more efficient energy transfer process, resulting in a doubling of PL efficiency. Furthermore, Cs₂NaTbCl₆: Sb³⁺ NCs possess excellent X-ray scintillating performance with a low-dose detection limit of 140 nGy_air/s, which is nearly 5 times more sensitive than the undoped NCs. The optimized NCs show great application prospects in X-ray imaging. This work helps deepen the understanding of the luminescence mechanism, excited state dynamics, and scintillation property in Tb-based DP NCs.