Water‐Assisted Rapid Evaporation Synthesis of Transparent and Multicolor Luminescent Lanthanide‐Based Metal Halide Glasses for High‐Resolution X‐Ray Imaging

Abstract Organic–inorganic hybrid metal halide glasses are an emerging class of scintillators for high‐resolution X‐ray imaging, but their synthesis via conventional melt‐quenching method is hindered by thermal decomposition of organic components and strong recrystallization tendency. Moreover, the energy dissipation during relaxation of secondary electrons further limits their scintillation performance. To address these issues, a water‐assisted rapid evaporation method is developed that bypasses melting, enabling the synthesis of transparent, multicolor luminescent lanthanide‐based metal halide glasses, (BuTPP) 3 LnCl 6 (BuTPP + = butyltriphenylphosphonium). A triplet exciton‐mediated energy transfer mechanism is further introduced to enhance the utilization of secondary electrons. The incorporation of heavy lanthanides (such as Tb 3+ ) enhances spin‐orbit coupling in phosphorescent organic cations BuTPP⁺, promoting intersystem crossing and generating abundant triplet excitons during the relaxation of secondary electrons. These excitons undergo near‐unity energy transfer to Tb 3+ ions, facilitated by optimal energy level alignment (BuTPP⁺ triplet: 21739 cm −1 ; Tb 3+ 5 D 4 : 20492 cm −1 ), thereby minimizing energy dissipation and yielding intense radioluminescence. The representative (BuTPP) 3 TbCl 6 glass exhibits a high light yield comparable to commercial Bi 4 Ge 3 O 12 scintillator, outstanding spatial resolution (26.8 lp mm −1 ), and robust radiation stability. This work not only provides a scalable synthesis strategy for hybrid glasses but also establishes an effective exciton management strategy for high‐performance scintillators.