Fig. 1. Principle of X-ray scintillator detectors^[25]

Fig. 2. The β value of inorganic scintillators with different chemical bonds^[33]

Fig. 3. Widely used reference method for light yield measurement in recent years^[36]

Fig. 4. Luminescence mechanism corresponding to (a) scintillation decay time and (b) afterglow^［44］

Fig. 5. Typical structures of three-dimensional (3D), two-dimensional (2D), one-dimensional (1D), and zero-dimensional (0D) perovskites (purple polyhedron is metal halide polyhedron)^[48]

Fig. 6. Schematic diagram of different metal halide polyhedra configurations in zero-dimensional hybrid metal halide scintillators, where M represents metal ions (dark blue) and X represents halogen ions (light purple)^[52]

Fig. 7. Hybrid manganese based halide scintillators and composite films. (a) Comparison of RL intensities for the standard reference LuAG∶Ce and (C₃₈H₃₄P₂)MnBr₄ under dose rate of 20.8 μGy·s^-1 (inset shows the corresponding images under the same X-ray irradiation)^[54]; (b) RL intensity spectra (the thickness of 100 µm) normalized to X-ray attenuation efficiencies of C₄H₁₂NMnCl₃, (C₈H₂₀N)₂MnBr₄, and the reference LuAG∶Ce scintillator [light yields are calculated by integrating these RL spectra and comparing with light yield of reference LuAG∶Ce scintillator (22000 photons·MeV^-1)]^[55]; (c) afterglow curves of (C₈H₂₀N)₂MnBr₄^[55]; (d) crystal structure illustration of (Gua)₂MnCl₄ along a-axis^[60]; (e) scheme depicting the fabrication and photographs of the (C₂₄H₂₀P)₂MnBr₄-TPU scintillation film^[61]

Fig. 8. Hybrid manganese based halide scintillation single crystal. (a) Schematic diagram of the relation between imaging resolution and light scattering^[63]; (b) schematic diagram of a TEA₂MnI₄ crystal being grown by the local-heating solvent evaporation method, and photograph of TEA₂MnI₄ single crystal under daylight^[63]; (c) schematic diagram of X-ray imaging system, and X-ray imaging of TEA₂MnI₄ single crystal for standard pair card and a copper mesh with a scaffold width of 20 μm^[63]; (d) X-ray imaging resolution and (e) low limit of detection of (2-DMAP)₂MnBr₄ single crystals with different thicknesses^[64]

Fig. 9. Hybrid manganese based halide scintillation glass. (a) Preparation scheme and transmittance of (ETP)₂MnBr₄ transparent medium [inset shows photographs of (ETP)₂MnBr₄ transparent medium under daylight and UV light]^[65]; (b) molecular structure, melting temperature, and sample photographs of X₂MnBr₄ (X=TP, MTP, ETP, PTP, HTP) prepared through organic cation structure design^[67]; (c) photographs of fish through HTP₂MnBr₄ glass under daylight (above) and X-ray irradiation (below)^[67]; (d) fabrication process of TPP₂MnBr₄ transparent ceramic via the seed-crystal-induced cold sintering process^[68]; (e) photographs of TPP₂MnBr₄ ceramic and modulation transfer functions of X-ray images obtained from SCSP, CSP, and SS^[68]

Fig. 10. Hybrid tin based and antimony based halide scintillators. (a) Photographs of Bmpip₂SnBr₄ pellet under daylight and X-ray tube excitation (70 kV, 1 mA, 1.8 s exposure time), and the comparison of the normalized total amount of photons between Bmpip₂SnBr₄ and reference NaI∶Tl under the same X-ray excitation^[71]; (b) RL spectra of (PPN)₂SbCl₅ and CsI∶Tl under 50 keV X-ray excitation [inset shows a digital photograph of the (PPN)₂SbCl₅ crystals under X-ray irradiation]^[72]; (c) RL spectra of C₅₀H₄₄P₂SbCl₅, LuAG∶Ce and CsI∶Tl under the same conditions (dose rate 179.6 μGy·s^-1, voltage 50 kV, thickness 100 μm)^[73]; (d) MTF curve of C₅₀H₄₄P₂SbCl₅ scintillating screen^[73]

Fig. 11. Hybrid copper based halide scintillators. (a) Photographs of (TBA)CuX₂ (X=Cl, Br) single crystals under X-ray irradiation (above), and (TBA)CuX₂ flexible films under UV excitation (below)^[76]; (b) scintillation decay profile of (Bmpip)₂Cu₂Br₄ at ²⁴¹Am^[78]; (c) PL decay curve of BMPCBI^[79]; (d) detailed structural view of the [Cu₄Br₁₀]^6- tetramer, [BAPMA]³⁺ cation, and [BAPMA]Cu₂Br₅ along the b-axis^[80]; (e) photographs of [BAPMA]Cu₂Br₅ flexible scintillation screen (left) and MTF curve (right)^[80]; (f) photographs of copper iodide hybrid crystals containing different chiral R-2-mpip, S-2-mpip, and R,S-2-mpip cations under visible light and UV irradiation condition^[82]

Fig. 12. Relationship between the performance and optical yield of zero dimensional lead-free hybrid halide scintillators. (a) Relationship between PLQY and light yield of reported 0D hybrid Mn-based (green), Cu-based (blue), and Sb- based (orange) halide scintillators; (b) relationship between the distance (M-M) between the luminescent polyhedra and their light yield of reported 0D hybrid Mn-based (green) and Cu-based (orange) halide scintillators

Fig. 13. Illustration of the mechanisms that lead to the immobile excitons in (C₄N₂H₁₄X)₄SnX₆ (X = Br, I) and the mobile excitons in Cs₄PbBr₆^[84]