Braddock Isabel H B, Al Sid Cheikh Maya, Ghosh Joydip, Mulholland Roma E, O'Neill Joseph G, Stolojan Vlad, Crean Carol, Sweeney Stephen J, Sellin Paul J
Department of Physics, University of Surrey, Guildford GU2 7XH, UK.
Department of Chemistry, University of Surrey, Guildford GU2 7XH, UK.
Nanomaterials (Basel). 2022 Jun 22;12(13):2141. doi: 10.3390/nano12132141.
While there is great demand for effective, affordable radiation detectors in various applications, many commonly used scintillators have major drawbacks. Conventional inorganic scintillators have a fixed emission wavelength and require expensive, high-temperature synthesis; plastic scintillators, while fast, inexpensive, and robust, have low atomic numbers, limiting their X-ray stopping power. Formamidinium lead halide perovskite nanocrystals show promise as scintillators due to their high X-ray attenuation coefficient and bright luminescence. Here, we used a room-temperature, solution-growth method to produce mixed-halide FAPbX3 (X = Cl, Br) nanocrystals with emission wavelengths that can be varied between 403 and 531 nm via adjustments to the halide ratio. The substitution of bromine for increasing amounts of chlorine resulted in violet emission with faster lifetimes, while larger proportions of bromine resulted in green emission with increased luminescence intensity. By loading FAPbBr3 nanocrystals into a PVT-based plastic scintillator matrix, we produced 1 mm-thick nanocomposite scintillators, which have brighter luminescence than the PVT-based plastic scintillator alone. While nanocomposites such as these are often opaque due to optical scattering from aggregates of the nanoparticles, we used a surface modification technique to improve transmission through the composites. A composite of FAPbBr3 nanocrystals encapsulated in inert PMMA produced even stronger luminescence, with intensity 3.8× greater than a comparative FAPbBr3/plastic scintillator composite. However, the luminescence decay time of the FAPbBr3/PMMA composite was more than 3× slower than that of the FAPbBr3/plastic scintillator composite. We also demonstrate the potential of these lead halide perovskite nanocomposite scintillators for low-cost X-ray imaging applications.
虽然在各种应用中对有效且价格合理的辐射探测器有很大需求，但许多常用的闪烁体存在重大缺陷。传统的无机闪烁体具有固定的发射波长，并且需要昂贵的高温合成；塑料闪烁体虽然速度快、价格便宜且坚固耐用，但原子序数较低，限制了它们对X射线的阻止能力。甲脒铅卤化物钙钛矿纳米晶体因其高X射线衰减系数和明亮的发光特性而有望成为闪烁体。在此，我们采用室温溶液生长法制备了混合卤化物FAPbX3（X = Cl、Br）纳米晶体，其发射波长可通过调整卤化物比例在403至531 nm之间变化。用溴替代越来越多的氯会导致紫色发射，且寿命更快，而更大比例的溴会导致绿色发射，发光强度增加。通过将FAPbBr3纳米晶体加载到基于PVT的塑料闪烁体基质中，我们制备了1毫米厚的纳米复合闪烁体，其发光比单独的基于PVT的塑料闪烁体更亮。虽然这样的纳米复合材料由于纳米颗粒聚集体的光散射通常是不透明的，但我们使用了一种表面改性技术来改善通过复合材料的透射率。封装在惰性PMMA中的FAPbBr3纳米晶体复合材料产生了更强的发光，强度比对比的FAPbBr3/塑料闪烁体复合材料大3.8倍。然而，FAPbBr3/PMMA复合材料的发光衰减时间比FAPbBr3/塑料闪烁体复合材料慢3倍以上。我们还展示了这些铅卤化物钙钛矿纳米复合闪烁体在低成本X射线成像应用中的潜力。
