Highly Efficient, Flexible, and Eco-Friendly Manganese(II) Halide Nanocrystal Membrane with Low Light Scattering for High-Resolution X-ray Imaging

Abstract

Scintillators enable invisible X-ray to be converted into ultraviolet (UV)/visible light that can be collected using a sensor array and is the core component of the X-ray imaging system. However, combining the excellent properties of high light output, high spatial resolution, flexibility, non-toxicity, and cost effectiveness into a single X-ray scintillator remains a great challenge. Herein, a novel scintillator based on benzyltriphenylphosphonium manganese(II) bromide (BTP2MnBr4) nanocrystal (NC) membranes was developed by the in situ fabrication strategy. The long Mn–Mn distance provided by the large BTP cation allows the nonradiative energy dissipation in this manganese(II) halide to be significantly suppressed. As a result, the flexible BTP2MnBr4 NC scintillator shows an excellent linear response to the X-ray dose rate, a high light yield of ∼71,000 photon/MeV, a low detection limit of 86.2 nGyair/s at a signal-to-noise ratio of 3, a strong radiation hardness, and a long-term thermal stability. Thanks to the low Rayleigh scattering associated with the dense distribution of nanometer-scale emitters, light cross-talk in X-ray imaging is greatly suppressed. The impressively high-spatial resolution X-ray imaging (23.8 lp/mm at modulation transfer function = 0.2 and >20 lp/mm for a standard pattern chart) was achieved on this scintillator. Moreover, well-resolved 3D dynamic rendering X-ray projections were also successfully demonstrated using this scintillator. These results shed light on designing efficient, flexible, and eco-friendly scintillators for high-resolution X-ray imaging.

Transparent Organic and Metal Halide Tandem Scintillators for High-Resolution Dual-Energy X-ray Imaging

“…Ultimately, two superimposed X-ray images, consisting of an orange emission carrying low-energy X-ray information and a green emission carrying high-energy X-ray information, were collected simultaneously by the sensor array. In addition, it should be noted that both top and bottom scintillators have been proven to exhibit excellent radiation stability as previously reported. , …”

“…Manganese­(II) ions in the tetrahedral coordination possess unique electronic transitions corresponding to the energy splitting of their characteristic bands. Upon excitation, the BTP 2 MnBr 4 manganese halide exhibits an intense green emission with a PLQY of 67.8% (Figure S1), which is known to originate from the d–d transition ( 4 T 1 → 6 A 1 ). − It is noteworthy, as we reported previously, that the high light yield of the BTP 2 MnBr 4 manganese halide ensures that it can still display high scintillation brightness even after the energy and intensity of the X-rays have been attenuated by the top scintillator and filter . Ultimately, two superimposed X-ray images, consisting of an orange emission carrying low-energy X-ray information and a green emission carrying high-energy X-ray information, were collected simultaneously by the sensor array.…”

“…In addition, it should be noted that both top and bottom scintillators have been proven to exhibit excellent radiation stability as previously reported. 23,32 Moreover, due to the favorable solubility of most organic and organometallic chromophores in common solvents, transparent organic scintillators can be prepared through simple solution-processed drop-casting methods. And the BTP 2 MnBr 4 manganese halides can be facilely transformed from the crystalline to the glassy state by low-temperature melting, which endows it with high transparency.…”

“…These features are especially well-suited as the top scintillator that provides the low-energy X-ray absorption channel in dual-energy X-ray imaging based on the SSDLD system. On the other hand, manganese halides have been considered as an efficient X-ray scintillation material due to their ultrahigh light yield, negligible self-absorption, and the nonexistence of toxic elements. − Manganese halides contain metallic manganese elements that provide large X-ray absorption cross sections, and their low melting point allows them to be easily fabricated into thick transparent ceramics. These unique features of manganese halides meet the requirements for the bottom scintillator in dual-energy X-ray imaging based on the SSDLD system.…”

“…28−32 It is noteworthy, as we reported previously, that the high light yield of the BTP 2 MnBr 4 manganese halide ensures that it can still display high scintillation brightness even after the energy and intensity of the X-rays have been attenuated by the top scintillator and filter. 32 Ultimately, two superimposed X-ray images, consisting of an orange emission carrying lowenergy X-ray information and a green emission carrying highenergy X-ray information, were collected simultaneously by the sensor array. In addition, it should be noted that both top and bottom scintillators have been proven to exhibit excellent radiation stability as previously reported.…”