Ultrahigh Photoluminescence Quantum Yield Organic Manganese Halide Scintillator for X-ray Imaging

X-ray indirect detection based on metal halide scintillators has great potential in various applications, such as medical diagnosis, computerized tomography, and quality inspection. However, there are still many limitations in metal halide scintillation materials, such as toxicity, high production costs, and strong self-absorption caused by a band-edge transition limiting the photoluminescence quantum yield (PLQY). Here, (TEA)2MnCl4 and (TBA)2MnCl4 single crystals as scintillators with advanced properties were synthesized from TEAC (tetraethylammonium chloride), TBAC (tetrabutylammonium chloride), and manganese chloride by an antisolvent method at room temperature. These two zero-dimensional organometallic halides exhibit green emission peaking at 512 nm ((TBA)2MnCl4) and 524 nm ((TEA)2MnCl4) with high PLQYs of 99.96% and 65.07%, respectively. The ultrahigh PLQY of (TBA)2MnCl4 benefits from the long Mn–Mn distance in (TBA)2MnCl4. (TBA)2MnCl4 shows an outstanding scintillation performance with a high light yield of 21000 photons/MeV, a low detection limit of 381 nGy/s, and a spatial resolution of 5.6 lp/mm. X-ray imaging experiments demonstrate that the flexible scintillators based on (TEA)2MnCl4 and (TBA)2MnCl4 could be used in high-resolution X-ray imaging.