Preparation And Properties Of Zero-dimensional Metal Halide Scintillation Crystals

In recent years,low-dimensional metal halides have been paid considerable attention due to their unique electronic structures and excellent luminescent properties.Low-dimensional metal halides with high stopping power,high photoluminescence quantum yield（PLQY）,and strong self-trapped excitons（STEs）emission have shown potential applications in radiation detection.As scintillators,low-dimensional metal halides could convert invisible high-energy rays or particles into ultraviolet,visible or infrared light,and are widely used in fields including medical imaging,homeland security,and security inspections.Based on chemical conposition,low-dimensional metal halides can be divided into two categories:all-inorganic and organic-inorganic hybrids.Low-dimensional structures make the electron state localization and the exciton-phonon coupling enhanced,resulting in the preference of the formation of STEs and stronger excitons emission.These characteristics enable low-dimensional metal halides exhibiting high PLQY,large Stokes shift（self-absorption free）,and broad band emission.In addition,low-dimensional metal halides also have the advantages of high stability and ease of growth in solution.In this paper,zero-dimensional Cu（I）-based all-inorganic and organic-inorganic hybrid metal halides as well as Mn（II）-based organic-inorganic hybrid metal halides were prepared by a facile solution method,and their luminescent and scintillation properties were studied comprehensively.Centimeter-sized zero-diemnsional（0D）Cs₃Cu₂I₅single crystal has been successfully prepared by anti-solvent diffusion method.Cs₃Cu₂I₅crystals exhibit high PLQY,large Stokes shift,high light yield,ultra-low afterglow,and nonhygroscopic.Moreover,Cs₃Cu₂I₅present excellent X-ray andγ-ray detection performance,which is comparable to the Cs₃Cu₂I₅crystals prepared by the melt method.0D（Bmpip）₂Cu₂Br₄and PPh₄Cu Br₂has been successfully prepared by cooling crystallization method.（Bmpip）₂Cu₂Br₄has a broadband emission peak at 620 nm,a Stokes shift of 2.05 e V,and a high PLQY of 48.2%.（Bmpip）₂Cu₂Br₄ single crystal not only exhibits a high scintillation yield of 16,000 photons/Me V and a low X-ray detection limit of 0.71μGyair/s,but also displays a fast average decay time of 56 ns.These characteristics enable（Bmpip）₂Cu₂Br₄single crystal showing comparable potential in low-dose radiography and dynamic imaging applications.0D TBACu I₂（TBA represents tetrabutylammonium）and TPACu I₂（TPA represents tetrapropylammonium）single crystals were prepared by slow solvent evaporation method and cooling crystallization method,respectively.The crystal structures of TBACu I₂and TPACu I₂are monoclinic.They emit dual-band white light,covering the entire visible spectrum from 400 to 800nm,with two emission peaks at 473 and 678 nm for TBACu I₂and 488 and 634 nm for TPACu I₂,respectively.The decay time of TBACu I₂are 4.1 and 6.0μs respectively,and those of TPACu I₂are 3.7 and 5.6μs.These two different microsecond decay lifetimes combined with efficient ultra-broadband dual emission as well as large Stokes shifts indicate that both TBACu I₂and TPACu I₂have two independent trapped emission centers with two different traps excited state.The PLQY of TBACu I₂and TPACu I₂single crystals are 70.6%and 62.1%,respectively.The scintillation yields of TBACu I₂and TPACu I₂were 24,000 photons/Me V.The afterglow level of TBACu I₂and TPACu I₂were comparable to those of BGO,and the two samples exhibit low detection limits of 125 n Gy_air/s and 130 n Gy_air/s,respectively.We prepared an efficient 0D lead-free zero-dimensional X-ray scintillator(C₄₀H₃₈P₂)Mn Br₄by a facile anti-solvent diffusion method.The crystal structure of(C₄₀H₃₈P₂)Mn Br₄has been confirmed to be monoclinic.(C₄₀H₃₈P₂)Mn Br₄exhibits a green emission peaking at 518 nm,a high PLQY of 74.2%,a decent steady-state X-ray light yield of 32,000 photons/Me V,and a low detection limit of 288 n Gy_air/s.This organic manganese（II）hybrid(C₄₀H₃₈P₂)Mn Br₄single crystal is a promising scintillator for commercial applications due to its environmental friendliness,long-term stability,and excellent scintillation performance.