Solvent co-assembly in lead-free perovskite scintillators for stable and large-area X-ray imaging

Abstract

Perovskite scintillators have emerged as good candidates for next-generation X-ray detectors due to their excellent scintillation efficiency and controllable properties by compositions. However, moisture stability and large-area X-ray imaging are still major concerns. Here, we report two 0D lead-free perovskite structures with different ionic arrangements formed by co-assembling solvent molecules with perovskite ions. Different solvent molecules of hydrogen oxide (H₂O) and acetonitrile (CH₃CN) were self-assembled into a crystal lattice to modulate the ion arrangements of two new single crystals 4-diethylaminobenzoic acid manganese(II) bromide hydrogen oxide ((DABA)₂MnBr₄·H₂O) and 4-diethylaminobenzoic acid manganese(II) bromide acetonitrile ((DABA)₂MnBr₄·CH₃CN). The solvent co-assembled perovskite single crystal exhibits excellent moisture stability under ambient conditions for one month without any encapsulation, and is a good candidate for a low-cost and high-performance scintillator. The multiple supramolecular interactions within the two single crystals offer efficient driving forces for self-assembly, and the excitons are better confined in the (DABA)₂MnBr₄·H₂O crystals than that in (DABA)₂MnBr₄·CH₃CN crystals, resulting in a higher photoluminescence (PL) quantum yield of 51%. The light yield of (DABA)₂MnBr₄·H₂O to 120 keV can reach 28 333 photons MeV⁻¹. In addition, constructed strong hydrogen bonds in (DABA)₂MnBr₄·H₂O ensure good capability to suppress thermal PL quenching due to the reduced electron-phonon interactions. Large-area scintillators with a dimension size of 2.4 cm × 3.0 cm exhibit comparable X-ray imaging capability with spatial resolutions up to 5.0 lp mm⁻¹, providing a new design route for the perovskite scintillator family.