Gd/Tb/Eu alloyed double-perovskite lanthanide halides for color tunable photoluminescence and robust scintillation performance

Abstract

Double-perovskite materials with diverse elemental compositions have been developed as high-performance phosphors and scintillators. However, the low doping concentration of activator ions in the host matrix limits the flexible tuning of luminescence properties. In this work, we propose a series of gadolinium, terbium, and europium alloyed double-perovskite lanthanide chlorides (DPLCs) to achieve color-tunable photoluminescence (PL) as well as thermally and radiationally stable X-ray excited optical luminescence (XEOL). The Cs₂NaGdCl₆ host allows up to 100% and 60% doping concentrations of Tb³⁺ ions for PL and XEOL, respectively, without concentration quenching. The designed Cs₂NaTbCl₆ exhibits a high photoluminescence quantum yield of 73.5%. Optical encryption was achieved using Cs₂NaTb_0.95Eu_0.05Cl₆, which shows excitation-wavelength-dependent dynamic emission colors. Benefiting from efficient energy transfer from Gd³⁺ to Tb³⁺ in the XEOL process, Cs₂NaGd_0.4Tb_0.6Cl₆ achieves a high light yield of 27 000 ph MeV⁻¹. With the incorporation of Eu³⁺, Cs₂NaTbGd_0.35Tb_0.6Eu_0.05Cl₆ exhibits excellent thermal and radiation stability for scintillation. Moreover, DPLCs embedded in polymethyl methacrylate (PMMA) scintillator films enable high-resolution X-ray imaging with a spatial resolution of 16.6 lp mm⁻¹. This work provides a novel strategy for designing DPLCs with state-of-the-art optical applications.