Environment-Regulated Crystal-Structure Reconfiguration of Hybrid Halide Scintillators Enables Tunable STE Emission...

Developing intelligent x-ray scintillators requires precise regulation of scintillation emission. However, the complex structural factors governing luminescence in organic-inorganic hybrid metal halides (OIMHs, A_mBX_n) remain elusive, limiting their rational design. Here, guided by condensed-matter structural chemistry, we develop an environment-regulated crystal-structure reconfiguration strategy that directs the same precursor system to generate three structurally distinct zero-dimensional (0D) scintillators: (C₉H₁₃N₂O)₄In₂Cl₁₀:Sb³⁺ (Crystal 1, dimeric), (C₉H₁₃N₂O)₂(H₅O₂)InCl₆:Sb³⁺ (Crystal 2, octahedral), and (C₉H₁₃N₂O)₄(InCl₆)[InCl₄(H₂O)₂]:Sb³⁺ (Crystal 3, mixed-ligand octahedral). Mechanistic studies reveal that [BX_n] configurations determine lattice distortion and electron-phonon coupling, A-[BX_n] interactions regulate lattice rigidity, and X-site coordination environments further modulate excited-state redistribution and radiative relaxation, establishing clear structure-scintillation relationships. The three crystals exhibit tunable green-to-red self-trapped exciton (STE) emission and complementary x-ray scintillation properties, with Crystal 2 achieving a photoluminescence quantum yield of 95.2% and an x-ray light yield of 27 522 photons MeV^-1, while highly transparent Crystal 1 enables a spatial resolution of 24 lp mm^-1 at a thickness of 0.85 mm. Furthermore, reversible stimulus-responsive luminescence switching among these scintillators enables environmental sensing and programmable x-ray imaging. This work provides a structural chemistry strategy for understanding STE emission in 0D OIMHs and designing reconfigurable scintillators toward intelligent x-ray imaging.