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CN-121992476-A - High-resolution ultrafast scintillator based on exciton space diffusion limiting strategy and preparation method thereof

CN121992476ACN 121992476 ACN121992476 ACN 121992476ACN-121992476-A

Abstract

The invention belongs to the technical field of X-ray imaging, and particularly relates to a high-resolution ultrafast scintillator based on an exciton space diffusion limiting strategy and a preparation method thereof. The invention utilizes the space limiting effect of the nano through hole template to reduce the dimension of PEA 2 PbBr 4 from bulk single crystal to uniform one-dimensional nanowire, thereby realizing the space localization of bulk exciton under X-ray excitation. Spatially localized bulk excitons significantly shorten the decay time of the radiation-induced luminescence (from 11.85 ns to 1.87 ns). Meanwhile, due to the periodic optical waveguide structure which is arranged regularly, scintillation photons generated by the PEA 2 PbBr 4 nanowire array can directionally propagate along the waveguide structure, and transverse light propagation and crosstalk effects are reduced, so that high-spatial resolution imaging (MTF0.2=57.1 lp/mm) is realized. The strategy provides a reference for promoting the application of the organic-inorganic hybrid perovskite material in the field of ultra-fast ray imaging.

Inventors

  • ZHENG WEI
  • SONG XIAOYU

Assignees

  • 中山大学

Dates

Publication Date
20260508
Application Date
20260126

Claims (9)

  1. 1. A method of preparing a scintillator based on an exciton space diffusion confinement strategy, the method comprising the steps of: (1) Preparing an organic-inorganic hybrid perovskite precursor solution; (2) Dropwise adding an organic-inorganic hybridization perovskite precursor solution onto a pre-cleaned substrate, enabling a nano-porous anodic alumina template to be in contact with the liquid drop, firstly contacting one surface, then lowering the other surface, enabling the solution to completely permeate the template, and keeping for a certain time; (3) And carrying out negative pressure auxiliary pre-infiltration on the infiltrated AAO template and the substrate, releasing vacuum, then carrying out negative pressure heating nanowire growth, cooling after the growth is completed, and stripping the substrate to obtain the organic-inorganic hybrid perovskite array scintillation screen.
  2. 2. The method of preparing a scintillator based on an exciton space diffusion confinement strategy of claim 1, wherein the organic-inorganic hybrid perovskite is PEA 2 PbBr 4 .
  3. 3. The method of claim 1, wherein in step (2), the maintaining for a certain period of time means maintaining for 2 to 5 minutes.
  4. 4. The method of claim 1, wherein in step (3), the negative pressure-assisted pre-permeation is performed at a pressure of-70 kPa ℃, a temperature of 60 ℃, and a time of 5 minutes.
  5. 5. The method of claim 1, wherein in step (3), the negative pressure heating is performed at a pressure of-70 kPa ℃ and a temperature of 60 ℃.
  6. 6. A scintillator based on the exciton space diffusion limiting strategy prepared by the preparation method of any one of claims 1 to 5.
  7. 7. The scintillator based on the exciton spatial diffusion confinement strategy of claim 6, wherein when the organic-inorganic hybrid perovskite is PEA 2 PbBr 4 , the resulting PEA 2 PbBr 4 array scintillation screen has a radiation decay lifetime of 1.87 ns under excitation of the 241 Am gamma ray source of 59.5 keV.
  8. 8. The scintillator based on the exciton spatial diffusion confinement strategy of claim 6, wherein when the organic-inorganic hybrid perovskite is PEA 2 PbBr 4 , the resulting PEA 2 PbBr 4 array scintillating screen has a spatial resolution of 57.1 lp/mm at MTF = 0.2.
  9. 9. Use of a scintillator based on the exciton space diffusion confinement strategy as claimed in any of claims 6-8 in ultra fast X-ray imaging.

Description

High-resolution ultrafast scintillator based on exciton space diffusion limiting strategy and preparation method thereof Technical Field The invention belongs to the technical field of X-ray imaging, and particularly relates to a high-resolution ultrafast scintillator based on an exciton space diffusion limiting strategy and a preparation method thereof. Background Scintillator-based X-ray imaging plays an irreplaceable role in the fields of high-energy physics experiments, medical radiodiagnosis (CT, DR), industrial nondestructive testing, security inspection, geological exploration, and the like. With the development and expansion of the field of X-ray imaging, ultra-fast X-ray imaging has shown a vigorous development trend in recent years as an emerging and very potential research direction. Compared with the traditional static X-ray imaging, the ultra-fast X-ray imaging with nanosecond or even sub-nanosecond time resolution can accurately capture transient image information and realize real-time monitoring of a dynamic process, and has important values in scenes such as lithium cell cathode lithium dendrite growth dynamics monitoring, molten pool monitoring in metal additive manufacturing, fluid ultra-high speed imaging (including internal combustion engine spray fluid dynamics research), pulse radiation field imaging and the like. Conventional inorganic scintillators, such as CsI: tl, naI: tl, GOS ceramics, YAG: ce, etc., typically have a considerable light yield (> 25000 photons/MeV) and acceptable decay times (greater than tens or hundreds of nanoseconds), which can meet the performance requirements in most application scenarios. However, when applied to ultrafast X-ray imaging applications, the decay time of conventional inorganic scintillators has been difficult to meet the requirements of ultrafast decay. This dilemma motivates the research and application of new scintillators with ultrafast decay time characteristics. In recent years, the organic-inorganic hybrid perovskite material has high PLQY, better environmental adaptability and luminescence tunability due to the natural quantum well structure, and has application potential in the fields of photoelectric detectors, quantum dot LEDs, photovoltaic devices and the like. Among many organic-inorganic hybrid perovskite materials, PEA 2PbBr4 (PHENETHYL LEAD Bromide, phenethyl lead Bromide (C 6H5CH2CH2NH3)2PbBr4) has been identified as a very potential candidate for the fields of ultrafast radiation and high energy particle detection due to its moderate band gap, high radiation absorption coefficient, high hydrogen content, high light yield, and ultrafast decay time. However, when facing the practical application of ultra-fast X-ray imaging, PEA 2PbBr4 still faces two major bottlenecks, firstly, the PEA 2PbBr4 layered structure results in different decay behavior of surface and bulk excitons. Under high-penetration X-ray excitation, the dominant bulk exciton emission has a slower decay time (> 10 ns) which is detrimental to ultra-fast X-ray imaging. Second, the growth of PEA 2PbBr4 single crystals is usually carried out by slow solvent evaporation at room temperature or by temperature-reduced crystallization. However, the solubility of PEA 2PbBr4 varies drastically with temperature, which makes single crystal growth susceptible to uncontrolled polycrystalline growth, thereby making large-size, high-quality, imaging-usable PEA 2PbBr4 single crystals difficult to obtain and process. These factors are detrimental to expanding the application of PEA 2PbBr4 in the field of ultra-fast X-ray imaging. Therefore, there is a need to develop a manufacturing strategy that can shorten the decay time of PEA 2PbBr4 under X-ray excitation and achieve a large area of uniform scintillation screen. Disclosure of Invention Aiming at the problems in the prior art, the application provides a high-resolution ultrafast scintillator based on an exciton space diffusion limiting strategy and a preparation method thereof. The design concept of the PEA 2PbBr4 nanowire (Nano Wires, NWs) array scintillation screen (PNSS) with ultrafast attenuation and high resolution characteristics is shown in fig. 1, and the organic-inorganic perovskite PEA 2PbBr4 is regarded as an ideal candidate material of an ultrafast scintillator (shown in (a) of fig. 1) because of the combination of high light yield (> 40000 photons/MeV) and sub-nanosecond level attenuation time (particularly, photoluminescence attenuation time < 600 ps). However, when ultra-fast imaging applications are performed with higher energy X-rays/gamma rays, there is a significant extension in decay time of PEA 2PbBr4 single crystals (16.9 ns). This phenomenon is disadvantageous for ultra-fast X-ray imaging applications. Recent studies of exciton kinetics on PEA 2PbBr4 crystals by the present inventors have shown that differences in density between surface and bulk excitons of PEA 2PbBr4 crystals or cause significant prolonga