Reflective ultrafast scintillation vacuum ultraviolet light imaging detection system and method thereof

Abstract

The present application relates to the field of electronic detector, disclose a kind of reflective ultrafast scintillation vacuum ultraviolet light imaging detection system and method thereof, including optical path system, detection and recording component and structural support component, the optical path system is reflective optical path configuration, including main mirror, secondary mirror, correction lens, integrated filter and vacuum ultraviolet scintillator, the material of the vacuum ultraviolet scintillator is PEA2PbBr4 Crystal or BA2PbBr4 Crystal.The present application successfully demonstrates its ability in vacuum ultraviolet (VUV) scintillation imaging by constructing reflective optical path configuration.The present application not only provides a new solution to reduce the influence of self-absorption effect in perovskite scintillator, but also builds a bridge between perovskite scintillator and practical application in ultrafast VUV detection, opening up a new road for the application of perovskite materials in VUV imaging field.

Description

Technical Field

[0001] This invention relates to the field of electronic detectors, and more particularly to a reflective ultrafast scintillation vacuum ultraviolet imaging detection system and method thereof. Background Technology

[0002] Vacuum ultraviolet (VUV, wavelength range 10 to 200 nm) light detection technology plays a crucial role in space science and radiation monitoring, providing indispensable value for space exploration missions, space physics research, and applications of synchrotron radiation sources and free-electron lasers. By accurately capturing VUV radiation information emitted by various celestial targets, this technology provides invaluable data support for cutting-edge scientific research fields such as space weather forecasting and the exploration of the origin and evolution of the universe. With the increasing demand for VUV light detection, research on photodetectors based on wide-bandgap semiconductor materials such as diamond, aluminum nitride (AlN), and gallium oxide (Ga2O3) has become increasingly critical. To achieve accurate capture of the motion details of targets in the VUV radiation environment, an ideal detector should possess a picosecond-level fast response time. However, these high-performance detectors face many challenges in practical applications, including high manufacturing costs, complex integration processes, and the difficulty in achieving the ideal fast response time. Therefore, exploring a VUV light detection method that combines simple synthesis processes with fast response characteristics has become a major technical challenge that urgently needs to be solved in this field.

[0003] As an alternative research approach, researchers are actively exploring the application potential of high-performance scintillating materials. These materials can effectively convert vacuum ultraviolet (VUV) light into visible light and accurately capture VUV imaging information while achieving rapid scintillation. Specifically, organic scintillators have been successfully applied to the detection of VUV imaging information. Han et al. developed a real-time VUV radiation monitoring system based on sodium salicylate and compared photon intensities in different wavelength ranges using various filters. However, it is worth noting that the hygroscopicity and aging phenomena of sodium salicylate scintillators may adversely affect their long-term performance. This is mainly due to the system's susceptibility to environmental pollutants (such as vacuum pump oil), ultraviolet radiation, and water vapor. Therefore, although organic scintillators have shown good performance in certain specific applications, they may not be the optimal choice in terms of long-term stability. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a reflective ultrafast scintillation vacuum ultraviolet imaging detection system and method. Compared with traditional transmission systems, the imaging detection system of this invention improves the response time by approximately 2.6 times, providing a new technical path for ultrafast detection in the vacuum ultraviolet (VUV) band.

[0005] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a reflective ultrafast scintillation vacuum ultraviolet imaging detection system, comprising an optical path system, a detection and recording component, and a structural support component. The optical path system is a reflective optical path configuration, and a secondary mirror, a primary mirror, an integrated filter, and a vacuum ultraviolet scintillator are sequentially arranged before and after the optical path system. The optical path system is also provided with a correction lens, the diameter of which is larger than that of the secondary mirror, and the correction lens is sleeved and connected to the secondary mirror or located at the front end of the optical path system. The primary mirror is a concave mirror, and the secondary mirror is a convex mirror. The material of the vacuum ultraviolet scintillator is PEA2PbBr4 crystal or BA2PbBr4 crystal.

[0006] Furthermore, a hollow sleeve is inserted through the middle of the primary mirror, and the integrated filter is installed at the rear end of the hollow sleeve.

[0007] Furthermore, the integrated filter consists of an outer protective layer, a metal reflective layer, multiple interference films, an absorption layer, and a VUV transmission substrate.

[0008] Furthermore, the outer protective layer of the integrated filter is made of ultrathin Si3N4; the metal reflective layer is made of aluminum thin film; the multilayer interference film is an alternating Si / Mo layer; the absorption layer is made of carbon thin film; and the VUV transmission substrate is a LiF window.

[0009] Furthermore, the thickness of the ultrathin Si3N4 is less than 10 nm; the thickness of the aluminum film is 40–60 nm; the total thickness of the Si / Mo alternating layer is 400–600 nm; the thickness of the carbon film is 15–25 nm; and the thickness of the LiF window is 1–2 mm.

[0010] Furthermore, the detection and recording component is a charge-coupled device, and the structural support component is a lens barrel.

[0011] Furthermore, the preparation method of the PEA2PbBr4 or BA2PbBr4 crystal material of the vacuum ultraviolet scintillator includes the following steps: Step S1: Dissolve phenethylamine hydrobromide or butylammonium bromide in N,N-dimethylformamide solvent at a stoichiometric ratio of 2:1, stir and heat, and then filter to obtain polycrystalline material and transparent saturated precursor solution 1. Step S2: Dissolve the polycrystalline material in N,N-dimethylformamide to obtain a new saturated precursor solution 2. Evaporate and crystallize the precursor solution 1 at room temperature to obtain transparent PEA2PbBr4 or BA2PbBr4 seed crystals. Step S3: Add the seed crystal to the precursor solution 2 and slowly evaporate to further grow PEA2PbBr4 or BA2PbBr4 crystals.

[0012] Furthermore, in step S1 of the method for preparing PEA2PbBr4 or BA2PbBr4 crystals, after stirring and heating at 50-80 °C for 20-30 h, the polycrystalline material and a transparent saturated precursor solution 1 are obtained by filtration.

[0013] Furthermore, in step S3 of the method for preparing PEA2PbBr4 or BA2PbBr4 crystals, the crystals are further grown by slowly evaporating at a temperature of 20–40 °C for 60–84 h.

[0014] In a second aspect, the present invention provides a detection method for the aforementioned reflective ultrafast scintillation vacuum ultraviolet light imaging detection system. The light signal is processed via a reflective optical path configuration of the optical path system, comprising the following steps: after correction by the correcting lens, the light is reflected by the concave mirror of the primary mirror, then converged by the convex mirror of the secondary mirror to adjust the optical path. Subsequently, vacuum ultraviolet light with a wavelength range of 10–200 nm is filtered through an integrated filter. The filtered vacuum ultraviolet light is then clearly imaged on the vacuum ultraviolet scintillator. The light signal processed by the optical path system is converted into an electrical signal by a detection and recording component and then stored and transmitted.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention optimizes the optical path system, enabling the imaging detection system to effectively avoid self-absorption effects and utilize surface excitons to achieve efficient light utilization and rapid scintillation. Through the coordinated operation of its components, the imaging system of this invention can achieve high-quality imaging of specific targets and specific spectral ranges, with potential applications in astronomical observation, spectral analysis, and other fields.

[0016] 2. The PEA2PbBr4 crystal or BA2PbBr4 crystal prepared by this invention exhibits extremely high transparency and can clearly transmit the text underneath, which provides a solid foundation for its application in the field of imaging.

[0017] 3. The PEA2PbBr4 crystal of the present invention has a fast decay time, which can provide higher time resolution and can be used to accurately capture and analyze transient events; in addition, the PEA2PbBr4 crystal of the present invention performs well in terms of luminous efficiency, which provides strong support for its application in high-performance detection systems.

[0018] 4. This invention constructs a reflective optical imaging system for VUV light, which can rapidly and clearly capture imaging details, thereby achieving clear imaging. Its performance far surpasses that of traditional scintillators. Therefore, it fully demonstrates its enormous potential in the field of scintillation imaging. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure and optical path of the reflective ultrafast scintillation vacuum ultraviolet light imaging detection system of Embodiment 1 of the present invention.

[0020] Figure 2 a is an optical photograph of the PEA2PbBr4 crystal under white light in Embodiment 2 of the present invention; Figure 2 b and Figure 2 c are SEM images of the (001) top view and (010) cross-section of the PEA2PbBr4 single crystal in Test Example 1, respectively; Figure 2 d represents the powder XRD pattern of a single PEA2PbBr4 crystal and the theoretically calculated powder XRD pattern.

[0021] Figure 3 This is an optical photograph of the BA2PbBr4 crystal under white light in Embodiment 2 of the present invention.

[0022] Figure 4 The following is a summary diagram and schematic diagram of the decay time of PEA2PbBr4 crystal under different excitation sources in Test Example 2 of the present invention.

[0023] Figure 5 a is a graph showing the absorption coefficient and penetration depth of PEA2PbBr4 single crystal in test example 2 of the present invention; Figure 5 b is a schematic diagram of the penetration depth of vacuum ultraviolet light, ultraviolet light, and X-ray in PEA2PbBr4 single crystal.

[0024] Figure 6 The image shows the UV-Vis transmission spectrum of the PEA2PbBr4 single crystal from Example 3 of this invention.

[0025] Figure 7 a and Figure 7 b represents the photoluminescence spectra of the PEA2PbBr4 crystal in Test Example 3 of this invention, measured in reflection and transmission modes under 193 nm excitation.

[0026] Figure 8The time-resolved fluorescence spectra of PEA2PbBr4 in Example 3 of this invention, with emission peaks at 409 nm and 435 nm under 213 nm excitation, are shown.

[0027] Figure 9 a is a bar chart showing the decay time of the PEA2PbBr4 crystal and a common scintillator in Test Example 4 of the present invention; Figure 9 b is a three-dimensional comparison diagram of the PLQY, decay time, and emission peak of the PEA2PbBr4 crystal in Test Example 4 of this invention with common commercial scintillators sodium salicylate and YAG:Ce.

[0028] Figure 10 a is the temperature-dependent TRPL-Mapping plot at 409 nm for test example 5 of the present invention; Figure 10 b is a graph showing the decay time of the 409 nm emission peak as a function of temperature; Figure 10 c is an image of the reflective ultrafast scintillation vacuum ultraviolet light imaging detection system based on Example 1 in Test Example 5 of this invention.

[0029] In the picture: 1-Primary mirror; 2-Secondary mirror; 3-Correction lens; 4-Integrated filter; 5-Vacuum ultraviolet scintillator; 6-Charge-coupled device; 7-Mirror barrel. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field.

[0031] Example 1: Reflective Ultrafast Scintillation Vacuum Ultraviolet Imaging Detection System and Method This embodiment is used to provide the reflective ultrafast scintillation vacuum ultraviolet light imaging detection system and method of the present invention. Figure 1 This is a schematic diagram of the structure and optical path of the reflective ultrafast scintillation vacuum ultraviolet imaging detection system of the present invention. Figure 1As shown in the structural diagram, a reflective ultrafast scintillation vacuum ultraviolet light imaging detection system consists of three parts: an optical path system, a detection and recording component, and a structural support component. The optical path system of the imaging detection system is arranged sequentially at the front and rear of a secondary mirror 2, a primary mirror 1, an integrated filter 4, and a vacuum ultraviolet scintillator 5. The optical path system also includes a correction lens 3, the diameter of which is larger than that of the secondary mirror 2. The correction lens 3 is sleeved and connected to the secondary mirror 2 or located at the front end of the optical path system. In one specific implementation, a hollow sleeve is inserted through the middle of the primary mirror 1, and the integrated filter 4 is installed at the rear end of the hollow sleeve.

[0032] In this invention, the structural support component can be a lens barrel 7, and the detection and recording component can be a charge-coupled device 6. Wherein: The primary mirror 1 is designed as a concave mirror, which is used as a core component to collect and initially converge light from the target. By utilizing the reflective properties of the concave mirror, the light is directed to propagate in a specific direction. Secondary mirror 2 is a convex mirror, used to further process the light reflected from the primary mirror. The converging effect of the convex mirror can adjust the light path, allowing the light to be focused more accurately and improving the imaging accuracy. Correction lens 3 is used to correct aberrations and chromatic aberrations generated during light propagation, making the image clearer and more accurate, and reducing image distortion caused by the characteristics of the optical elements themselves; specifically, correction lens 3 can be a Schmidt correction lens. The integrated filter 4 is specifically structured as follows: an outer protective layer (ultra-thin silicon nitride, Si3N4, thickness <10 nm, used to prevent oxidation and mechanical damage), a metal reflective layer (aluminum thin film, thickness approximately 50 nm, used to reflect visible / infrared light), a multilayer interference film (Si / Mo alternating layers, total thickness approximately 500 nm, used to enhance VUV transmission and secondary reflection of stray light), an absorption layer (carbon thin film, thickness approximately 20 nm, used to absorb transmitted long-wavelength residue), and a VUV transmission substrate (LiF window, thickness 1–2 mm, used to provide mechanical support and final VUV transmission). In this invention, the integrated filter 4 is used to filter ultraviolet light (wavelength 10–200 nm) within a specific wavelength range to pass through, while blocking other interfering wavelengths. The vacuum ultraviolet scintillator 5 can be made of VUV scintillator, such as PEA2PbBr4 crystal or BA2PbBr4 crystal. When vacuum ultraviolet light is incident, the vacuum ultraviolet scintillator 5 can convert vacuum ultraviolet photons into visible light photons, realizing the conversion of invisible vacuum ultraviolet light into visible light for subsequent detection.

[0033] The detection and recording component (charge-coupled device 6) is used to convert the optical signal processed by the optical path system into an electrical signal, and to store and transmit it. It is a key component for converting optical images into electronic data for subsequent processing and display.

[0034] Structural support component (lens tube 7): It serves to support and protect the internal optical elements, ensure the accurate relative position of each element, and maintain the stability of the convex mirror in the optical path.

[0035] In this invention, a reflective ultrafast scintillation vacuum ultraviolet imaging detection method is provided, such as... Figure 1 As shown in the optical path diagram, the optical signal is processed by the reflective optical path configuration of the optical path system, including the following steps: After the light is corrected by the corrective lens 3 to adjust the light path, it is reflected by the concave mirror of the primary mirror 1, and then the light path is adjusted by the converging effect of the secondary mirror 2. Subsequently, it passes through the integrated filter 4, which can filter out vacuum ultraviolet light in a specific wavelength range (10-200 nm). The vacuum ultraviolet light filtered by the integrated filter 4 is clearly imaged on the vacuum ultraviolet scintillator 5.

[0036] The optical signal processed by the optical path system is converted into an electrical signal by a detection and recording component, which is then stored and transmitted. The detection and recording component is configured as a charge-coupled device (CCD) 6. This invention optimizes the optical path system, enabling the imaging detection system to effectively avoid self-absorption effects, thereby achieving efficient light utilization and rapid scintillation. Through the coordinated operation of its components, the imaging system of this invention can achieve high-quality imaging of specific targets and specific spectral ranges, with potential applications in astronomical observation, spectral analysis, and other fields.

[0037] Example 2: Growth method of vacuum ultraviolet scintillator PEA2PbBr4 and BA2PbBr4 single crystals This embodiment provides a method for growing PEA2PbBr4 crystals of the vacuum ultraviolet scintillator 5 in the imaging detection system of the present invention. In this embodiment, all experimental reagents and solvents were commercially available and no further purification was performed.

[0038] Traditional anti-solvent diffusion crystallization methods typically produce small crystal particles (usually a few millimeters) with uneven surfaces and low transparency, which limits their potential in practical applications such as imaging. Therefore, this invention employs a strategy combining solvent evaporation and seed crystal-induced growth to promote further crystal growth. PEA2PbBr4 or BA2PbBr4 crystals are synthesized by placing the seed crystal in a saturated N,N-dimethylformamide (DMF) solution and evaporating it at room temperature. The specific steps of synthesizing and growing PEA2PbBr4 or BA2PbBr4 crystals are as follows: Step S1: Phenethylamine hydrobromide (PEABr) or butylammonium bromide (BABr): lead bromide (PbBr2) is dissolved in N,N-dimethylformamide (DMF) solvent at a stoichiometric ratio of 2:1. After stirring and heating at 65 °C for 24 h, the mixture is filtered to obtain PEA2PbBr4 or BA2PbBr4 polycrystalline material and a transparent saturated precursor solution 1. Step S2: Dissolve the polycrystalline material in DMF to obtain a new saturated precursor solution 2; evaporate and crystallize the precursor solution 1 at room temperature to obtain transparent PEA2PbBr4 or BA2PbBr4 seed crystals. Step S3: Finally, the seed crystal is added to the precursor solution 2 and slowly evaporated at 30 °C for 72 h to further grow into PEA2PbBr4 crystals (20 mm × 12 mm × 2 mm) or BA2PbBr4 crystals (30 mm × 7 mm × 1 mm) with high transparency and larger size.

[0039] Using the above preparation method, transparent and flat PEA2PbBr4 crystals and BA2PbBr4 crystals with dimensions of 11 mm × 8 mm and 30 mm × 7 mm, respectively, were successfully synthesized in this embodiment. Optical photographs of the PEA2PbBr4 crystals and BA2PbBr4 crystals under white light are shown below. Figure 2 a and Figure 3 As shown. By Figure 2 a and Figure 3 As can be seen, the PEA2PbBr4 crystal and BA2PbBr4 crystal prepared in this embodiment exhibit extremely high transparency, and can clearly transmit the text or patterns underneath, which provides a solid foundation for their application in the field of imaging.

[0040] Example 3: Testing and Characterization Methods and Instruments This embodiment provides the test characterization methods and instrumentation used in the following test embodiments. In these test embodiments, X-ray diffraction (XRD) was performed on a Panalytical X'Pert Pro X-ray diffractometer with a copper X-ray tube voltage of 45 kV and a current of 40 mA. The calculated XRD results were obtained using Crystal Maker and CrystalDiffract software. Scanning electron microscopy (SEM) images were obtained on a Hitachi SU5000 instrument at an accelerating voltage of 10 kV, with magnifications of 120 for the top view and 2500 for the cross-section.

[0041] Ultraviolet-visible spectroscopy was measured using a Shimadzu UV-3600-Plus spectrophotometer. The excitation source for PL spectroscopy consisted of an EX5 / 250-478 excimer 193 nm (ArF) laser, a DPS-213-Pico diode-pumped all-solid-state 213 nm picosecond laser (pulse width: 44.37 ps), and a 365 nm LED lamp. The optical signal was collected using an Ocean Optical QE65 Pro spectrometer. Transient fluorescence spectroscopy (TRPL) was performed using a specially designed VUV Edikurgh FLS1000 transient fluorescence spectrometer equipped with a 213 nm picosecond laser. The sample was stored in a cryostat regulated by liquid nitrogen. The temperature was automatically adjusted from 77 K to 300 K, and data was recorded every 10 K increase. Time-resolved radiative decay time was measured using time-correlated single-photon counting with an Am gamma-ray source as the excitation source. The PMT used for the test was a HAMAMATSU R2083, and the oscilloscope was a Lecroy with a 1 GHz bandwidth and a 10 Gs / s sampling rate. All optical images were taken using a Nikon D850 optical camera.

[0042] Furthermore, all calculations were performed using first-principles simulations on the VASP program. The electron exchange potential and correlation potential were described by a generalized gradient approximation with the Perdew-Burke-Ernzerhof (PBE) exchange correlation energy, and the plane wave cutoff energy was set to 400 eV.

[0043] Test Example 1: Internal Structure Analysis of PEA2PbBr4 Single Crystal To reveal the internal structure of the PEA2PbBr4 single crystal of this invention, scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to analyze the structure of the PEA2PbBr4 single crystal. The results are as follows: Figure 2 b~ Figure 2 As shown in d. Wherein, Figure 2 b and Figure 2 c are SEM images of the (001) top view and (010) cross-section of a PEA2PbBr4 single crystal, respectively; Figure 2 d represents the powder XRD pattern of a single PEA2PbBr4 crystal and the theoretically calculated powder XRD pattern.

[0044] Scanning electron microscopy (SEM) is used to observe the cross-section and surface morphology of samples, and is a powerful means to reveal their internal structure. As can be observed from the figure, the (010) cross-section exhibits a distinct layered structure (see figure). Figure 2 c), while the (001) surface is composed of irregular thin sheets (see c), and the (001) surface is composed of irregular thin sheets (see c). Figure 2(b) This result further confirms that the crystal growth process proceeds in a layer-by-layer manner, which is consistent with the unique layered structure of PEA2PbBr4 crystal, formed by the interlacing of organic and inorganic layers.

[0045] Figure 2 The XRD pattern of PEA2PbBr4 crystal showed that the characteristic diffraction peaks (00l) (l=2,3,4,5,6,7) were all sharp and intense, and no impurity peaks were observed. This result fully demonstrates the high crystallinity and high purity of PEA2PbBr4 single crystal. Furthermore, this test compared the XRD results of PEA2PbBr4 single crystal with the theoretically calculated powder XRD results, further confirming the layered structure characteristics of PEA2PbBr4 single crystal (see [reference]). Figure 2 d).

[0046] Test Example 2: Study on decay time and penetration depth of PEA2PbBr4 crystal under different excitation sources This test example was used to study the decay time and penetration depth of PEA2PbBr4 crystals under different excitation sources (vacuum ultraviolet light, ultraviolet light, and X-ray). A summary table and schematic diagram of the decay time of PEA2PbBr4 crystals under different excitation sources are shown in Table 1 and [Table 2 missing in original text]. Figure 4 As shown. Among them, Figure 4 a and Figure 4 b represents a summary graph and a curve showing the decay time of PEA2PbBr4 crystals under different excitation sources. Here, Ex represents the excitation wavelength, Em represents the emission peak, and τ represents the decay time.

[0047] Table 1 Summary of decay times of PEA2PbBr4 crystal under different excitation sources X-ray 440 35 X-ray 432 16.9 X-ray 438 14 γ-ray 435 12.3 γ-ray 434 15.4 γ-ray 435 19.32 440 nm 430 6.28 340 nm 432 5.54 320 nm 434 1.61 213 nm 409 0.60 Table 1 and Figure 4 The results show that the decay time of PEA2PbBr4 crystal is approximately tens of nanoseconds in radiative emission, while it is shortened to a few nanoseconds in photoluminescence. Furthermore, the decay time under photoluminescence exhibits a trend of decreasing with decreasing excitation wavelength. When using shorter wavelengths for excitation, charge carriers tend to approach the crystal surface more readily, thereby enhancing the sensitivity to surface processes. Therefore, this invention hypothesizes that this phenomenon is closely related to the penetration depth of excitation light at different wavelengths.

[0048] To verify the above hypothesis, this test further calculated the absorption coefficient of the PEA2PbBr4 crystal using VASP to determine the penetration depth of light in the crystal. The results are as follows: Figure 5 As shown. Among them, Figure 5 a is a graph showing the absorption coefficient and penetration depth of PEA2PbBr4 single crystal; Figure 5b is a schematic diagram of the penetration depth of vacuum ultraviolet light, ultraviolet light, and X-ray in PEA2PbBr4 single crystal.

[0049] The results show that in the VUV band, the penetration depth of PEA2PbBr4 crystal is extremely small, approximately 10–30 nm from the crystal surface, significantly shorter than that of ultraviolet and visible light (e.g., ...). Figure 5 (As shown in a). Furthermore, because VUV light has a shallow penetration depth within the crystal, its effect on the crystal surface is significant, while X-rays have high energy and a large penetration depth, thus they can excite the interior of the crystal (e.g., ...). Figure 5 (as shown in b).

[0050] Test Example 3: Optical Properties of PEA2PbBr4 Crystal This test example is used to study the optical properties of the PEA2PbBr4 crystal of the present invention. Figure 6 This is the UV-Vis transmission spectrum of a PEA2PbBr4 single crystal. Figure 6 As shown, the absorption edge of the PEA2PbBr4 crystal is located at 425 nm.

[0051] Furthermore, this study investigated the photoluminescence (PL) spectra of PEA2PbBr4 crystals under different optical path configurations. Photoluminescence (PL) spectra were measured using both reflective and transmissive optical paths under 193 nm excitation, and the results are as follows: Figure 7 As shown. Among them, Figure 7 a is the PL spectrum measured under 193 nm excitation in a reflective optical path. Figure 7 b is the PL spectrum of 193 nm excitation measured under a transmission optical path.

[0052] The results show that, under reflective measurement, the PEA2PbBr4 crystal, excited at 193 nm, exhibits a main emission peak at 409 nm (e.g., ...). Figure 7 (as shown in a); however, under transmission electron microscopy (TEM) measurements, the PEA2PbBr4 crystal only shows an emission peak at 435 nm, without the emission peak at 409 nm (as shown in a). Figure 7 (as shown in b). This is because, under transmission mode detection, the 409 nm emitted photons generated on the surface are strongly absorbed by the interior of the crystal due to the self-absorption effect and cannot reach the detector, while the 435 nm emitted in the bulk phase (with energy lower than the absorption edge) can penetrate the crystal and be detected.

[0053] Figure 8 The image shows the time-resolved fluorescence (TRPL) spectrum under 213 nm excitation. The results indicate that the 409 nm emission peak has a short lifetime of 600 ps, ​​attributed to surface exciton recombination; while the 435 nm emission peak exhibits a longer decay lifetime of 1.55 ns, corresponding to bulk exciton recombination (see...). Figure 8This is because the self-absorption effect of PEA2PbBr4 crystal makes it difficult to utilize surface excitons, while the reflective vacuum ultraviolet imaging detection system of this invention can effectively utilize surface emission.

[0054] Test Example 4: Comparative Analysis of PEA2PbBr4 Crystal and Common Commercial Scintillators This test example is used to compare and analyze the PEA2PbBr4 scintillator crystal of the present invention with common commercial scintillators. The results are as follows: Figure 9 As shown. Among them, Figure 9 a is a bar chart of the decay time of PEA2PbBr4 crystal and common scintillators, where Ex represents the excitation wavelength, Em represents the emission peak, and τ represents the decay time; Figure 9 b is a three-dimensional comparison of the PLQY, decay time, and emission peak of PEA2PbBr4 crystal with common commercial scintillators sodium salicylate and YAG:Ce.

[0055] The results show that most commercially available scintillators have decay times in the microsecond and nanosecond range, while picosecond-level scintillators are relatively rare. PEA2PbBr4 has a decay time of only 600 ps, ​​which is five orders of magnitude faster than Cs3Cu2I5 (1.92 μs) and nearly six times faster than the currently promising CsPbBr3 (3.4 ns) perovskite scintillator (e.g., PEA2PbBr4). Figure 9 (As shown in a). Therefore, PEA2PbBr4 has a significant advantage over the decay times of commercially available VUV scintillators sodium salicylate (10 ns) and YAG:Ce (70 ns). Traditional scintillators typically have long decay times, often on the microsecond scale, which often result in a significant "tailing" effect, prolonging the signal duration and thus affecting the resolution of subsequent events. PEA2PbBr4, with its ultrafast decay time, provides higher temporal resolution, which is crucial for accurately capturing and analyzing transient events.

[0056] Furthermore, the PLQY values ​​of PEA2PbBr4, sodium salicylate, and YAG:Ce were 32.1%, 40.2%, and 50.7%, respectively (e.g., ...). Figure 9 (As shown in b). Although the PLQY value of PEA2PbBr4 is slightly lower than that of commercial materials, its single crystal PLQY is higher than that of many perovskite single crystals, such as CsCu2I3 single crystal (PLQY = 15.7%). Therefore, the PEA2PbBr4 crystal of this invention exhibits good potential in terms of luminescence efficiency and fast response time, providing strong support for its application in high-performance detection systems.

[0057] Test Example 5: Scintillation Performance and Imaging Test of Vacuum Ultraviolet Imaging Detector under Low Temperature Conditions In actual vacuum ultraviolet (VUV) detection missions, the space environment is extremely cold, with temperatures reaching below -10 °C or even lower. Therefore, scintillator materials used for vacuum UV detection must possess excellent low-temperature tolerance and stability of low-temperature optical properties to meet stringent detection requirements. To this end, time-resolved photoluminescence (TRPL) tests were conducted on PEA2PbBr4 crystals at temperatures ranging from 77 K to 300 K to verify their scintillation performance under low-temperature conditions. The results are as follows: Figure 10 As shown.

[0058] in, Figure 10 a is the temperature-dependent TRPL-Mapping plot at 409 nm; Figure 10 b is a graph showing the decay time of the 409nm emission peak as a function of temperature; Figure 10 c is an image of an airplane, a puppy, flowers, and leaves under the reflective optical path configuration of Example 1, and the inset is a mask.

[0059] like Figure 10 a and Figure 10 As shown in b, the emission peak at 409 nm exhibits extremely fast decay times at different temperatures. By fitting an exponential decay function, the decay times at each temperature point were obtained, and all were very stable. This result indicates that the PEA2PbBr4 crystal has low sensitivity to temperature changes and exhibits excellent fluorescence stability. Therefore, the PEA2PbBr4 crystal of this invention exhibits relatively consistent fluorescence behavior at different temperatures, demonstrating significant advantages in vacuum ultraviolet scintillator applications.

[0060] However, a key problem remains with PEA2PbBr4 crystals—the self-absorption effect, which limits the effective utilization of surface excitons in practical VUV detection. Therefore, this invention constructs the reflective optical path configuration of Example 1. This configuration can utilize the surface exciton recombination effect of PEA2PbBr4 crystals to effectively mitigate the influence of self-absorption, thereby achieving ultrafast VUV scintillation imaging. Using this reflective optical path configuration, this invention successfully captured clear images of airplanes, dogs, flowers, and leaves (e.g.,...). Figure 10 (As shown in c). In dark environments, these images clearly reveal the contours and details of each shape, fully demonstrating the ability of the prepared PEA2PbBr4 crystal to identify complex targets and quickly recover the display. The image resolution is highly consistent with the shape of the object, indicating that the imaging system has high fidelity characteristics and foreshadows its potential application prospects in the field of vacuum ultraviolet imaging. Therefore, this invention, by constructing a reflective optical imaging system for VUV light, has enabled the PEA2PbBr4 single-crystal scintillator to successfully achieve clear imaging results, fully demonstrating its great potential in the field of scintillation imaging.

[0061] In summary, this invention ingeniously utilizes the rapid exciton recombination characteristic of the layered perovskite PEA2PbBr4 crystal surface to achieve ultrafast VUV reflective scintillation with a decay time of 600 ps. Furthermore, by constructing a reflective optical path configuration, this invention successfully demonstrates its capabilities in VUV scintillation imaging. This invention not only provides a new solution for reducing the influence of self-absorption effects in perovskite scintillators but also bridges the gap between perovskite scintillators and their practical application in ultrafast VUV detection, opening new avenues for the application of perovskite materials in the field of VUV imaging.

[0062] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A reflective ultrafast scintillation vacuum ultraviolet imaging detection system, characterized in that, It includes an optical path system, a detection and recording component, and a structural support component. The optical path system is a reflective optical path configuration, and a secondary mirror (2), a primary mirror (1), an integrated filter (4), and a vacuum ultraviolet scintillator (5) are arranged sequentially before and after the optical path system; wherein, The optical path system is also provided with a correction lens (3), the diameter of which is larger than the diameter of the secondary mirror (2), and the correction lens (3) is sleeved and connected to the secondary mirror (2) or located at the front end of the optical path system; The primary mirror (1) is a concave mirror, and the secondary mirror (2) is a convex mirror; The integrated filter (4) is used to filter vacuum ultraviolet light with a wavelength range of 10~200 nm. The integrated filter (4) consists of an outer protective layer, a metal reflective layer, a multilayer interference film, an absorption layer, and a VUV transmission substrate. The outer protective layer is made of ultrathin Si3N4; the metal reflective layer is made of aluminum thin film; the multilayer interference film is a Si / Mo alternating layer; the absorption layer is made of carbon thin film; the VUV transmission substrate is a LiF window; the thickness of the ultrathin Si3N4 is less than 10 nm; the thickness of the aluminum thin film is 40~60 nm; the total thickness of the Si / Mo alternating layer is 400~600 nm; the thickness of the carbon thin film is 15~25 nm; and the thickness of the LiF window is 1~2 mm. The vacuum ultraviolet scintillator (5) is made of PEA2PbBr4 crystal or BA2PbBr4 crystal, and is used to receive vacuum ultraviolet light filtered by the integrated filter and convert the vacuum ultraviolet light into visible light. The reflective optical path configuration is used to utilize the surface exciton emission of the vacuum ultraviolet scintillator to reduce the self-absorption effect caused by the propagation of surface-emitted light inside the crystal. The detection and recording component is used to receive and record the visible light signal generated by the vacuum ultraviolet scintillator.

2. The reflective ultrafast scintillation vacuum ultraviolet imaging detection system according to claim 1, characterized in that, A hollow sleeve is inserted in the middle of the main mirror (1), and the integrated filter (4) is installed at the rear end of the hollow sleeve.

3. The reflective ultrafast scintillation vacuum ultraviolet imaging detection system according to claim 1, characterized in that, The detection and recording component is a charge-coupled device (6), and the structural support component is a lens barrel (7).

4. The reflective ultrafast scintillation vacuum ultraviolet imaging detection system according to claim 1, characterized in that, The preparation method of the PEA2PbBr4 or BA2PbBr4 crystal of the vacuum ultraviolet scintillator (5) includes the following steps: Step S1: Dissolve phenethylamine hydrobromide or butylammonium bromide in N,N-dimethylformamide solvent at a stoichiometric ratio of 2:1, stir and heat, and then filter to obtain polycrystalline material and transparent saturated precursor solution 1. Step S2: Dissolve the polycrystalline material in N,N-dimethylformamide to obtain a new saturated precursor solution 2. Evaporate and crystallize the precursor solution 1 at room temperature to obtain transparent PEA2PbBr4 or BA2PbBr4 seed crystals. Step S3: Add the seed crystal to the precursor solution 2 and slowly evaporate to further grow PEA2PbBr4 or BA2PbBr4 crystals.

5. The reflective ultrafast scintillation vacuum ultraviolet imaging detection system according to claim 4, characterized in that, In step S1 of the method for preparing PEA2PbBr4 or BA2PbBr4 crystals, after stirring and heating at 50-80 °C for 20-30 h, the polycrystalline material and a transparent saturated precursor solution 1 are obtained by filtration.

6. The reflective ultrafast scintillation vacuum ultraviolet imaging detection system according to claim 4, characterized in that, In step S3 of the method for preparing PEA2PbBr4 or BA2PbBr4 crystals, the crystals are slowly evaporated at a temperature of 20–40 °C for 60–84 h, and then further grown to obtain PEA2PbBr4 or BA2PbBr4 crystals.

7. The detection method of the reflective ultrafast scintillation vacuum ultraviolet imaging detection system as described in any one of claims 1 to 6, characterized in that, The light signal is processed by the reflective optical path configuration of the optical path system, including the following steps: After the light is corrected by the correction lens (3), it is reflected by the concave mirror of the primary mirror (1), and then the light path is adjusted by the converging effect of the convex mirror of the secondary mirror (2). Subsequently, the vacuum ultraviolet light with a wavelength range of 10 to 200 nm is filtered by the integrated filter (4) and then clearly imaged on the vacuum ultraviolet scintillator (5). The light signal processed by the optical path system is converted into an electrical signal by the detection and recording components and stored and transmitted.

Images