A flexible scintillator screen having low dose x-ray imaging performance and process thereof
By using the highly efficient 2D perovskite scintillator material Cs2AgBiBr6 and a transparent conductive polymer layer in the scintillator screen, combined with micro-nano structures and gradient design, the problems of light loss and signal difference in low-dose X-ray imaging were solved, achieving high efficiency and stability in low-dose X-ray imaging.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHENGZHOU UNIV
- Filing Date
- 2026-02-04
- Publication Date
- 2026-06-05
Smart Images
Figure CN122161284A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of scintillator screen technology, specifically to a flexible scintillator screen with low-dose X-ray imaging performance and its manufacturing process. Background Technology
[0002] In the field of X-ray imaging, with the increasing demands for image quality and radiation safety in applications such as medical diagnosis and industrial inspection, low-dose X-ray imaging technology has become a research hotspot. However, existing scintillator screens face many challenges in achieving low-dose X-ray imaging.
[0003] On the one hand, traditional scintillator materials have limited X-ray absorption efficiency, making it difficult to generate sufficiently strong fluorescence signals under low-dose X-ray irradiation. For example, in medical diagnosis, the detection of small lesions such as early-stage tumors requires higher imaging resolution and sensitivity, which existing scintillator screens often cannot meet. On the other hand, the intensity of X-rays gradually attenuates with increasing penetration depth as they penetrate an object, resulting in differences in the X-ray dose received at different locations on the scintillator screen. This leads to significant light loss and low light collection efficiency, further limiting the improvement of imaging performance. Summary of the Invention
[0004] To address the shortcomings of existing technologies, this invention provides a flexible scintillator screen with low-dose X-ray imaging performance and its manufacturing process, which solves the problems of high light loss and low light collection efficiency that limit imaging performance.
[0005] To achieve the above objectives, the present invention provides the following technical solution: a flexible scintillator screen with low-dose X-ray imaging performance, comprising a high-efficiency 2D perovskite scintillator material layer, a transparent conductive polymer layer, and a flexible substrate, wherein the high-efficiency 2D perovskite scintillator material is Cs2AgBiBr6; the flexible substrate is a polyimide film or a PET film; the transparent conductive polymer layer is disposed on one or both sides of the surface of the high-efficiency 2D perovskite scintillator material layer, and the transparent conductive polymer layer material is PEDOT:PSS or PANI.
[0006] The above scheme employs the following approach: Cs2AgBiBr6 is selected as the high-efficiency 2D perovskite scintillator material. Its high X-ray absorption coefficient (μ / ρ) ≥50cm² / mg, combined with the exciton confinement effect of the 2D structure, can improve light conversion efficiency, stabilize chemical properties to enhance material stability, and its specific band gap and luminescence lifetime are beneficial for imaging. The flexible substrate uses a 5-50μm thick polyimide film (high temperature resistance, high strength) or PET film (high transparency, low cost) to ensure optical performance and structural strength. The transparent conductive polymer layer material is PEDOT:PSS or PANI, which is set on one or both sides of the scintillator material layer. PEDOT:PSS improves signal response with its high conductivity and solution processability, while PANI optimizes charge transport with stable electrical properties, and the setting method can be adjusted as needed to balance performance and cost.
[0007] Preferably, the surface of the high-efficiency 2D perovskite scintillator material layer is provided with a micro-nano structure, which is a photonic crystal array with a period of 200-500nm or a plasma-enhanced structure of metallic silver / gold nanoparticles with a height of 50-200nm; the photonic crystal array is formed by hot pressing.
[0008] Preferably, the high-efficiency 2D perovskite scintillator material layer has a gradient structure, adopting a "core-shell" composite structure along the thickness direction of 0-100μm: the core region is a Cs2AgBiBr6 single crystal with a concentration of 80wt%, and the shell layer is a Cs2AgBiBr6 / PVDF-HFP composite phase with a concentration that linearly decreases from 80wt% to 30wt%, or the material layer thickness is dynamically adjusted from 50μm at the edge to 150μm at the center by adjusting the height of the mold head, forming an X-ray absorption gradient distribution.
[0009] A fabrication process for a flexible scintillator screen with low-dose X-ray imaging performance includes the following steps:
[0010] S1: CsBr, AgNO3 and BiBr3 are dissolved in an ethanol-acetone mixed solvent with a volume ratio of 1:1 at a molar ratio of 1:0.8:0.8. The mixture is magnetically stirred at 60°C for 3 hours. Cs2AgBiBr6 crystals are rapidly precipitated by antisolvent method. After grinding to a particle size ≤200nm, the crystals are dispersed in a polyimide / NMP solution with a solid content of 15wt% to form a scintillator slurry with a solid content of 40wt%.
[0011] S2: The scintillator slurry is coated onto a flexible substrate using a slot coating method to a thickness of 80 μm, and then dried at 100°C for 1.5 h to form a high-efficiency 2D perovskite scintillator material layer; during the drying process, moisture residue is avoided.
[0012] S3: A 3wt% PEDOT:PSS aqueous solution was deposited onto the surface of the scintillator material layer through a slit at a speed of 8 mm / s. The PEDOT:PSS aqueous solution contained 5 vol% ethylene glycol and 0.5 wt% lithium sulfate. The solution was annealed at 130°C for 45 min to form a transparent conductive polymer layer. A segmented heating method was used during the annealing process.
[0013] S4: An encapsulation layer is formed by alternating deposition of Al2O3 on the surface of a transparent conductive polymer layer through atomic layer deposition, using 20 cycles / 30 cycles of SiO2.
[0014] Preferably, in step S2, when preparing the high-efficiency 2D perovskite scintillator material layer, a 3D printing-ALD composite process is adopted. First, a PLA sacrificial layer skeleton with a pore size of 200-500μm is prepared by inkjet printing technology with an inkjet printing resolution of ≤50μm. Then, at 60℃, 20-30 cycles of deposition are performed using Cs-cyclopentadienyl, Ag-acetylacetone, and Bi-trimethyl precursors to form a nanocrystalline coating with a thickness of 50-100nm in the skeleton pores. Finally, the sacrificial layer is dissolved by solvent to construct a three-dimensional interconnected scintillator network.
[0015] Preferably, step S2 employs an aerosol jetting-thermal embossing integrated technology: a scintillator nano-slurry with a solid content of 25wt% is directly printed through a nozzle with a nozzle diameter of 80μm. The dispersant for the scintillator nano-slurry is N-methylpyrrolidone with a particle size ≤100nm. The array structure is directly printed at a printing speed of 30mm / s and an air pressure of 0.2MPa. Simultaneously, a photonic crystal structure with a period of 200nm is formed on the surface of the material layer through a thermal embossing mold, thus achieving one-step preparation of the micro / nano structure and the material layer.
[0016] Preferably, the gradient structure in step S2 is prepared by twin-screw co-extrusion coating: a high-concentration slurry, namely Cs2AgBiBr6 80wt%, and a low-concentration slurry, namely Cs2AgBiBr6 30wt%+PVDF-HFP, are respectively fed through twin screws. After dynamic mixing in the die, the slurry is extruded, so that the solid content of the coating slurry decreases linearly from the center to the edge of the die, directly forming a concentration gradient along the thickness direction, thus avoiding the stress problem of layer-by-layer coating.
[0017] Preferably, after the encapsulation layer is prepared in S4, an Al2O3 / SiO2 nanolayer is first formed by atomic layer deposition, and then a 50μm thick UV-curable PDMS layer containing 0.1wt% nano TiO2 is spin-coated. A hydrophobic and moisture-proof composite layer is formed by UV curing. The UV curing is performed at 365nm and the energy is 100mJ / cm², so that the encapsulated scintillator screen is tested for 1000h at 85℃ / 85%RH.
[0018] Preferably, the inkjet-printed sacrificial layer skeleton uses water-soluble PVA material, with a printing linewidth of 100-300μm and a pore size distribution uniformity of ≥90%. Non-destructive demolding is achieved by dissolving in deionized water (temperature 60℃, time 10min). The temperature during deionized water dissolution is 60℃ and the time is 10min. During the dissolution process of PVA material, stirring is added.
[0019] Preferably, after doping the transparent conductive polymer layer in S3, the crystallinity of PEDOT:PSS is further optimized by laser annealing. The wavelength of the laser annealing is 532nm and the power density is 0.1-0.5J / cm².
[0020] This invention provides a flexible scintillator screen with low-dose X-ray imaging performance and its manufacturing process. It offers the following advantages:
[0021] 1. This invention significantly improves low-dose X-ray imaging performance by setting micro-nano structures on the surface of a high-efficiency 2D perovskite scintillator material layer and setting gradient structures in the material layer; the micro-nano structures can control the propagation and emission direction of the scintillator's light emission, improving light extraction efficiency or detection sensitivity; the gradient structures match the intensity differences of X-rays after penetrating the object, avoiding signal saturation or loss, and optimizing light collection efficiency and imaging quality.
[0022] 2. This invention integrates multiple innovative processes, including 3D printing-ALD composite process, aerosol jetting-thermal embossing integrated technology, and twin-screw co-extrusion coating method, to achieve efficient and precise fabrication of scintillator screens. These integrated process methods not only simplify the process flow and avoid interface defects that may be introduced by step-by-step fabrication, but also improve production efficiency and meet different application needs.
[0023] 3. After the encapsulation layer is prepared, this invention forms an Al2O3 / SiO2 nanolayer through atomic layer deposition, and then spin-coates a UV-curable PDMS layer containing nano-TiO2 to form a hydrophobic and moisture-proof composite layer. This multi-layer composite structure can provide long-term stable protection for the scintillator screen in harsh environments, effectively preventing moisture from corroding the scintillator material, ensuring the stable performance of the scintillator screen, and greatly improving the reliability and service life of the scintillator screen. Attached Figure Description
[0024] Figure 1 This is a schematic diagram of the preparation process of the present invention. Detailed Implementation
[0025] The technical solution of the present invention will now be clearly and completely described 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.
[0026] This invention provides a flexible scintillator screen with low-dose X-ray imaging performance, comprising a high-efficiency 2D perovskite scintillator material layer, a transparent conductive polymer layer, and a flexible substrate. The high-efficiency 2D perovskite scintillator material is Cs2AgBiBr6; the flexible substrate is a polyimide film or a PET film; the transparent conductive polymer layer is disposed on one or both sides of the high-efficiency 2D perovskite scintillator material layer, and the transparent conductive polymer layer material is PEDOT:PSS or PANI.
[0027] Specifically, the high-efficiency 2D perovskite scintillator material is Cs2AgBiBr6, with an X-ray absorption coefficient (μ / ρ) ≥50cm² / mg, a band gap of 3.4-3.6eV, and a luminescence lifetime of 25-35ns. The flexible substrate has a thickness of 5-50μm. The high X-ray absorption coefficient and stable chemical properties of Cs2AgBiBr6, combined with the exciton confinement effect of the 2D structure, improve light conversion efficiency and stability. The flexible substrate can be selected from polyimide film (high temperature resistance, high strength) or PET film (high transparency, low cost) to ensure optical performance and structural strength. The transparent conductive polymer layer uses PEDOT:PSS or PANI. The former improves signal response with high conductivity and solution processability, while the latter optimizes charge transport with stable electrical properties. The configuration can be adjusted as needed to balance performance and cost.
[0028] The surface of the high-efficiency 2D perovskite scintillator material layer is provided with micro-nano structures, which are either photonic crystal arrays with a period of 200-500nm or plasma-enhanced structures of metallic silver / gold nanoparticles with a height of 50-200nm; the photonic crystal array is formed by hot pressing.
[0029] Specifically, the photonic crystal array is formed by hot pressing, which improves the light extraction efficiency by 30%-50%. The plasmonic enhancement structure of metallic silver / gold nanoparticles is prepared by combining nanosphere photolithography with electron beam evaporation, which excites the local surface plasmonic resonance effect, enhances the electromagnetic field, and improves the electron-hole pair recombination efficiency, thereby increasing the detection sensitivity by more than 40%. The parameters of the two structures have been optimized through simulation and experiments to match the optical properties of Cs2AgBiBr6, and can be flexibly selected according to the application scenario. For example, the photonic crystal array is selected for medical diagnosis to improve resolution, while the metallic nanoparticle structure is selected for industrial detection to increase sensitivity, significantly enhancing the performance of low-dose X-ray imaging. The photonic crystal array is formed by hot pressing with a specific mold, and its structural parameters can be adjusted according to actual needs to optimize the light extraction efficiency.
[0030] The high-efficiency 2D perovskite scintillator material layer has a gradient structure, and adopts a "core-shell" composite structure along the thickness direction of 0-100μm: the core region is a single crystal of Cs2AgBiBr6 with a concentration of 80wt%, and the shell layer is a Cs2AgBiBr6 / PVDF-HFP composite phase with a concentration that linearly decreases from 80wt% to 30wt%. Alternatively, the thickness of the material layer can be dynamically adjusted from 50μm at the edge to 150μm at the center by adjusting the height of the mold head, thus forming an X-ray absorption gradient distribution.
[0031] Specifically, the core-shell composite gradient structure is distributed along a thickness of 0-100 μm. The core region uses 80 wt% Cs₂AgBiBr₆ single crystals, which efficiently absorb X-rays and convert them into optical signals. The shell layer is a Cs₂AgBiBr₆ / PVDF-HFP composite phase, with the concentration linearly decreasing from 80 wt% to 30 wt%. PVDF-HFP enhances the material's flexibility, reduces light scattering, optimizes the light propagation path, and improves light collection efficiency. The thickness gradient structure is achieved by dynamically adjusting the die height, resulting in a material layer thickness of 50 μm at the edge and 150 μm at the center. This design matches the intensity difference of X-rays after penetrating the object. The thicker central layer absorbs high-intensity X-rays to avoid signal saturation, while the thinner edge layer captures weak X-ray photons to prevent signal loss. High-precision extrusion equipment and an intelligent control system monitor and adjust extrusion parameters in real time to ensure a smooth and gradual thickness change. The formation of the gradient structure is achieved through precise control of relevant equipment parameters to ensure structural stability and performance consistency.
[0032] Please see the appendix Figure 1 A fabrication process for a flexible scintillator screen with low-dose X-ray imaging performance includes the following steps:
[0033] S1: CsBr, AgNO3 and BiBr3 are dissolved in an ethanol-acetone mixed solvent with a volume ratio of 1:1 at a molar ratio of 1:0.8:0.8. The mixture is magnetically stirred at 60°C for 3 hours. Cs2AgBiBr6 crystals are rapidly precipitated by antisolvent method. After grinding to a particle size ≤200nm, the crystals are dispersed in a polyimide / NMP solution with a solid content of 15wt% to form a scintillator slurry with a solid content of 40wt%.
[0034] S2: The scintillator slurry is coated onto a flexible substrate using a slot coating method to a thickness of 80 μm. It is then dried at 100°C for 1.5 h to form a high-efficiency 2D perovskite scintillator material layer. During the drying process, moisture residue is avoided.
[0035] S3: A 3wt% PEDOT:PSS aqueous solution was deposited onto the surface of the scintillator material layer through a slit at a speed of 8 mm / s. The PEDOT:PSS aqueous solution contained 5 vol% ethylene glycol and 0.5 wt% lithium sulfate. The solution was annealed at 130°C for 45 min to form a transparent conductive polymer layer. A segmented heating method was used during the annealing process.
[0036] S4: An encapsulation layer is formed by alternating deposition of Al2O3 on the surface of a transparent conductive polymer layer through atomic layer deposition, using 20 cycles / 30 cycles of SiO2.
[0037] Specifically, firstly, CsBr, AgNO3, and BiBr3 are dissolved in an ethanol-acetone mixed solvent at a molar ratio of 1:0.8:0.8. Cs2AgBiBr6 crystals are precipitated by magnetic stirring and an antisolvent method. After grinding to a particle size ≤200 nm, the precipitate is dispersed in a polyimide / NMP solution to form a scintillator slurry with a solid content of 40 wt%. In this step, the nanoscale particle size and high solid content increase the specific surface area, enhance X-ray absorption and fluorescence emission efficiency, and ensure sufficient fluorescence signal generation even under low-dose radiation. Next, the slurry is coated onto a flexible substrate using a slit coating method, with an 80 μm thickness and drying at 100°C for 1.5 h to ensure a uniform and dense coating, avoiding moisture residue that could degrade material properties, thereby improving imaging clarity and contrast and reducing noise. Subsequently, a 3wt% PEDOT:PSS aqueous solution containing ethylene glycol and lithium sulfate was coated at a speed of 8 mm / s, followed by segmented annealing at 130°C to form a transparent conductive layer. Ethylene glycol improves film formation properties, while lithium sulfate enhances conductivity. This conductive layer can efficiently collect charge, reduce signal attenuation, and improve charge transfer efficiency and imaging response speed. Finally, an encapsulation layer was formed through alternating cycles of Al2O3 (20 times) and SiO2 (30 times) atomic layer deposition, isolating moisture and oxygen to ensure device stability and long-term performance stability, making it suitable for medical and other scenarios requiring repetitive imaging.
[0038] Please see the appendix Figure 1In step S2, when preparing the high-efficiency 2D perovskite scintillator material layer, a 3D printing-ALD composite process is adopted. First, a PLA sacrificial layer skeleton with a pore size of 200-500μm is prepared by inkjet printing technology with an inkjet printing resolution of ≤50μm. Then, at 60℃, 20-30 cycles of deposition are performed using Cs-cyclopentadienyl, Ag-acetylacetone, and Bi-trimethyl precursors to form a nanocrystalline coating with a thickness of 50-100nm in the skeleton pores. Finally, the sacrificial layer is dissolved by solvent to construct a three-dimensional interconnected scintillator network.
[0039] Specifically, firstly, a sacrificial framework was prepared using polylactic acid (PLA) with high-precision inkjet printing technology. The pore size was precisely controlled between 200-500 μm, and the inkjet printing resolution was ≤50 μm, ensuring a uniform framework structure and reasonable pore distribution, providing a stable support structure for the subsequent nanocrystalline coating. Next, under a mild environment of 60℃, Cs-cyclopentadienyl, Ag-acetylacetone, and Bi-trimethyl were selected as precursors, and 20-30 atomic layer deposition (ALD) cycles were performed. The ALD process, through a self-limiting chemical reaction, precisely grows a dense nanocrystalline coating with a thickness of 50-100 nm on the inner wall of the framework pores. This coating possesses excellent scintillation properties, enabling efficient capture and conversion of X-ray energy. Finally, the PLA sacrificial layer was dissolved using a suitable solvent, and after removing the framework, a three-dimensional interconnected scintillator network was successfully constructed. This structure not only increases the interaction area between the scintillator and the X-ray, improving detection efficiency, but also optimizes the light transmission path, effectively enhancing the overall performance of the material.
[0040] Please see the appendix Figure 1 In step S2, an aerosol jetting-thermal embossing integration technology is used: scintillator nano-slurry with a solid content of 25wt% is directly printed through a nozzle with a nozzle diameter of 80μm. The dispersant of the scintillator nano-slurry is N-methylpyrrolidone with a particle size ≤100nm. The array structure is directly printed under the conditions of printing speed of 30mm / s and air pressure of 0.2MPa. At the same time, a photonic crystal structure with a period of 200nm is formed on the surface of the material layer through a thermal embossing mold, realizing the one-step preparation of micro-nano structure and material layer.
[0041] Specifically, in step S2, the aerosol jetting-thermal embossing integrated technology achieves efficient preparation. First, a scintillator nanoparticle slurry with a solid content of 25 wt% is selected. This ratio ensures good slurry flowability, preventing nozzle clogging, while also guaranteeing the density and performance of the printed material layer. N-methylpyrrolidone (NMP) is used as the dispersant because of its excellent dispersibility for scintillator nanoparticles, effectively preventing particle agglomeration and assisting in controlling slurry viscosity during printing. Nanoparticles with a particle size ≤100 nm impart a higher specific surface area and superior scintillator performance to the material layer. During printing, using a nozzle with a diameter of 80 μm, at a printing speed of 30 mm / s and an air pressure of 0.2 MPa, the slurry jetting volume and deposition position are precisely controlled to directly print the required array structure, ensuring dimensional accuracy and stability. Simultaneously, a photonic crystal structure with a period of 200 nm is formed on the surface of the material layer using a thermal embossing mold. This photonic crystal structure can regulate the propagation and emission direction of scintillator light emission, reducing light loss and improving light collection efficiency. The two technologies work together to achieve one-step fabrication of micro-nano structures and material layers, which not only simplifies the process but also avoids interface defects that may be introduced by stepwise fabrication, greatly improving production efficiency and product quality.
[0042] Please see the appendix Figure 1 In step S2, the gradient structure is prepared by twin-screw co-extrusion coating: a high-concentration slurry, namely Cs2AgBiBr6 80wt%, and a low-concentration slurry, namely Cs2AgBiBr6 30wt%+PVDF-HFP, are fed through twin screws respectively. After dynamic mixing in the die, the slurry is extruded, so that the solid content of the coating slurry decreases linearly from the center to the edge of the die, directly forming a concentration gradient along the thickness direction, thus avoiding the stress problem of layer-by-layer coating.
[0043] Specifically, in step S2, the gradient structure is prepared using a twin-screw co-extrusion coating method, which achieves high-efficiency production thanks to its unique material handling and molding mechanism. The twin screws deliver two key slurries: a high-concentration slurry with 80wt% Cs2AgBiBr6 content, which imparts excellent scintillation properties to the core region of the material; and a low-concentration slurry with 30% Cs2AgBiBr6 and PVDF-HFP added as a binder to optimize the material's flexibility and formability. Under the forced delivery of the twin screws, the two slurries are precisely and quantitatively pushed to the die. Once inside the die, through a special flow channel design and dynamic mixing structure, the two slurries achieve continuous and stable dynamic mixing within the die. As the slurry flows towards the die outlet, the difference in flow velocity distribution from the die center to the edge results in a linear decrease in the solid content of the coating slurry. When the slurry is coated onto the substrate, a concentration gradient structure is directly formed along the thickness direction. This one-step molding method avoids the stress problems caused by interlayer shrinkage differences in traditional layer-by-layer coating, ensuring the stability and integrity of the structure. Furthermore, by adjusting the ratio of the two slurries and the die parameters, the distribution characteristics of the gradient structure can be flexibly controlled to meet different application requirements.
[0044] Please see the appendix Figure 1 After the encapsulation layer is prepared in S4, an Al2O3 / SiO2 nanolayer is first formed by atomic layer deposition, and then a 50μm thick UV-curable PDMS layer containing 0.1wt% nano TiO2 is spin-coated. A hydrophobic and moisture-proof composite layer is formed by UV curing. The UV curing is performed at 365nm and the energy is 100mJ / cm². The encapsulated scintillator screen is tested for 1000h at 85℃ / 85%RH.
[0045] Specifically, after the S4 encapsulation layer is prepared, a multilayer composite process is used to improve the moisture-proof performance of the scintillator screen. First, Al2O3 / SiO2 nanolayers are alternately grown using atomic layer deposition (ALD) technology. Al2O3 possesses excellent chemical stability and barrier properties, effectively preventing water molecule penetration; SiO2 further fills the tiny pores of the Al2O3 layer, forming a dense nanoscale barrier layer to resist the intrusion of moisture from the environment. Subsequently, a 50μm thick UV-curable PDMS (polydimethylsiloxane) layer is spin-coated, with 0.1wt% nano-TiO2 added. Nano-TiO2 not only enhances the mechanical strength of the PDMS layer but also utilizes the hydrophobic properties of its nanoscale particles to reduce surface energy, making it difficult for water droplets to adhere. When cured with UV light at a wavelength of 365nm and an energy of 100mJ / cm², the PDMS molecular chains undergo a cross-linking reaction, rapidly forming a robust and continuous polymer film. This film is tightly bonded to the underlying Al2O3 / SiO2 nanolayer, constituting a hydrophobic and moisture-proof composite layer. This composite structure can provide stable protection for scintillator screens for up to 1000 hours in harsh environments of 85℃ / 85%RH, effectively preventing moisture from corroding the scintillator material and ensuring the stable performance of the scintillator screen.
[0046] Please see the appendix Figure 1 The inkjet-printed sacrificial layer skeleton uses water-soluble PVA material, with a printing line width of 100-300μm and a pore size distribution uniformity of ≥90%. Non-destructive demolding is achieved by dissolving in deionized water (temperature 60℃, time 10min). During the dissolution of PVA material, stirring is added.
[0047] Specifically, water-soluble polyvinyl alcohol (PVA) is selected for inkjet printing of the sacrificial layer skeleton due to its excellent film-forming properties and printability. By precisely controlling the inkjet printing parameters, the linewidth is maintained between 100-300 μm, while ensuring a pore size uniformity of ≥90%, thus forming a well-structured and uniformly porous skeleton network that provides a stable support substrate for subsequent functional layer deposition. The demolding process employs deionized water dissolution, continuously dissolving at 60°C for 10 minutes. This temperature setting avoids damage to the subsequent functional layer materials from high temperatures and utilizes temperature to increase the solubility of PVA in water, shortening the dissolution time. Stirring is added during dissolution to promote full contact between water and the PVA skeleton through mechanical force, accelerating solute diffusion. This allows PVA molecules to detach from the skeleton structure more quickly and uniformly disperses the microparticles generated during dissolution, preventing incomplete dissolution caused by excessively high local concentrations. This temperature-controlled dissolution process with stirring enables non-destructive demolding of the sacrificial layer—ensuring complete removal of the PVA skeleton while avoiding damage to the three-dimensional through-structure due to dissolution residues or mechanical stress, ultimately resulting in a scintillator network substrate with uniform porosity and a complete structure.
[0048] Please see the appendix Figure 1 After doping the transparent conductive polymer layer in S3, the crystallinity of PEDOT:PSS was further optimized by laser annealing. The wavelength of the laser annealing was 532nm and the power density was 0.1-0.5J / cm².
[0049] Specifically, after doping the transparent conductive polymer layer in S3, laser annealing was used to optimize the material properties of PEDOT:PSS. A 532nm laser was chosen because it is in the green light band and can be effectively absorbed by the conjugated structure in the PEDOT:PSS film. This wavelength also provides moderate penetration depth into the polymer matrix, allowing for internal structure modulation without damaging the substrate. The laser power density was controlled between 0.1-0.5 J / cm², providing sufficient energy to drive molecular chain movement while avoiding film ablation or decomposition due to excessive energy. During laser annealing, the instantaneous energy input of the pulsed laser locally heats the PEDOT:PSS film, inducing molecular chain rearrangement and crystallization. The increased orderliness of the PEDOT chains forms more continuous conductive pathways, thereby reducing film resistivity. Simultaneously, increased crystallinity reduces grain boundary scattering and enhances carrier mobility. This process achieves precise localized treatment through non-contact heating, offering advantages over traditional thermal annealing such as faster heating rates, controllable temperature fields, and no environmental pollution. After optimization, the conductivity of PEDOT:PSS film can be increased by 30%-50% while maintaining a visible light transmittance of over 85%, laying the foundation for the optoelectronic performance of subsequent devices.
[0050] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A flexible scintillator screen with low-dose X-ray imaging performance, characterized in that, The invention comprises a high-efficiency 2D perovskite scintillator material layer, a transparent conductive polymer layer, and a flexible substrate. The high-efficiency 2D perovskite scintillator material is Cs2AgBiBr6. The flexible substrate is a polyimide film or a PET film. The transparent conductive polymer layer is disposed on one or both sides of the surface of the high-efficiency 2D perovskite scintillator material layer. The transparent conductive polymer layer material is PEDOT:PSS or PANI.
2. The flexible scintillator screen with low-dose X-ray imaging performance according to claim 1, characterized in that, The surface of the high-efficiency 2D perovskite scintillator material layer is provided with micro-nano structures, which are photonic crystal arrays with a period of 200-500nm or plasma-enhanced structures of metallic silver / gold nanoparticles with a height of 50-200nm; the photonic crystal array is formed by hot pressing.
3. A flexible scintillator screen with low-dose X-ray imaging performance according to claim 1, characterized in that, The high-efficiency 2D perovskite scintillator material layer has a gradient structure, and adopts a "core-shell" composite structure along the thickness direction of 0-100μm: the core region is a Cs2AgBiBr6 single crystal with a concentration of 80wt%, and the shell layer is a Cs2AgBiBr6 / PVDF-HFP composite phase with a concentration that linearly decreases from 80wt% to 30wt%, or the material layer thickness can be dynamically adjusted from 50μm at the edge to 150μm at the center by adjusting the height of the mold head, forming an X-ray absorption gradient distribution.
4. The fabrication process of a flexible scintillator screen with low-dose X-ray imaging performance according to any one of claims 1-3, characterized in that, Includes the following steps: S1: CsBr, AgNO3 and BiBr3 are dissolved in an ethanol-acetone mixed solvent with a volume ratio of 1:1 at a molar ratio of 1:0.8:0.
8. The mixture is magnetically stirred at 60°C for 3 hours. Cs2AgBiBr6 crystals are rapidly precipitated by antisolvent method. After grinding to a particle size ≤200nm, the crystals are dispersed in a polyimide / NMP solution with a solid content of 15wt% to form a scintillator slurry with a solid content of 40wt%. S2: The scintillator slurry is coated onto a flexible substrate using a slot coating method to a thickness of 80 μm, and then dried at 100°C for 1.5 h to form a high-efficiency 2D perovskite scintillator material layer; during the drying process, moisture residue is avoided. S3: A 3wt% PEDOT:PSS aqueous solution was deposited onto the surface of the scintillator material layer through a slit at a speed of 8 mm / s. The PEDOT:PSS aqueous solution contained 5 vol% ethylene glycol and 0.5 wt% lithium sulfate. The solution was annealed at 130°C for 45 min to form a transparent conductive polymer layer. A segmented heating method was used during the annealing process. S4: An encapsulation layer is formed by alternating deposition of Al2O3 on the surface of a transparent conductive polymer layer through atomic layer deposition, using 20 cycles / 30 cycles of SiO2.
5. The fabrication process of a flexible scintillator screen with low-dose X-ray imaging performance according to claim 4, characterized in that, In step S2, when preparing the high-efficiency 2D perovskite scintillator material layer, a 3D printing-ALD composite process is adopted. First, a PLA sacrificial layer skeleton with a pore size of 200-500μm is prepared by inkjet printing technology with an inkjet printing resolution of ≤50μm. Then, at 60℃, 20-30 cycles of deposition are performed using Cs-cyclopentadienyl, Ag-acetylacetone, and Bi-trimethyl precursors to form a nanocrystalline coating with a thickness of 50-100nm in the skeleton pores. Finally, the sacrificial layer is dissolved by solvent to construct a three-dimensional interconnected scintillator network.
6. The fabrication process of a flexible scintillator screen with low-dose X-ray imaging performance according to claim 4, characterized in that, In step S2, an aerosol jetting-thermal embossing integration technology is used: a scintillator nano-slurry with a solid content of 25wt% is directly printed through a nozzle with a nozzle diameter of 80μm. The dispersant of the scintillator nano-slurry is N-methylpyrrolidone with a particle size ≤100nm. The array structure is directly printed under the conditions of printing speed of 30mm / s and air pressure of 0.2MPa. At the same time, a photonic crystal structure with a period of 200nm is formed on the surface of the material layer through a thermal embossing mold, realizing the one-step preparation of micro-nano structure and material layer.
7. The fabrication process of a flexible scintillator screen with low-dose X-ray imaging performance according to claim 4, characterized in that, In step S2, the gradient structure is prepared by twin-screw co-extrusion coating: a high-concentration slurry, namely Cs2AgBiBr6 80wt%, and a low-concentration slurry, namely Cs2AgBiBr6 30wt%+PVDF-HFP, are fed through twin screws respectively. After dynamic mixing in the die, the slurry is extruded, so that the solid content of the coating slurry decreases linearly from the center of the die to the edge, directly forming a concentration gradient along the thickness direction, avoiding the stress problem of layer-by-layer coating.
8. The fabrication process of a flexible scintillator screen with low-dose X-ray imaging performance according to claim 4, characterized in that, After the encapsulation layer is prepared in step S4, an Al2O3 / SiO2 nanolayer is first formed by atomic layer deposition, and then a 50μm thick UV-curable PDMS layer containing 0.1wt% nano TiO2 is spin-coated. A hydrophobic and moisture-proof composite layer is formed by UV curing. The UV curing is performed at 365nm and the energy is 100mJ / cm². The encapsulated scintillator screen is then tested at 85℃ / 85%RH for 1000h.
9. The fabrication process of a flexible scintillator screen with low-dose X-ray imaging performance according to claim 4, characterized in that, The inkjet-printed sacrificial layer skeleton uses water-soluble PVA material, with a printing linewidth of 100-300μm and a pore size distribution uniformity of ≥90%. Non-destructive demolding is achieved by dissolving in deionized water at a temperature of 60℃ for 10 minutes. Stirring is added during the dissolution process of the PVA material.
10. The fabrication process of a flexible scintillator screen with low-dose X-ray imaging performance according to claim 4, characterized in that, After the transparent conductive polymer layer is doped in step S3, the crystallinity of PEDOT:PSS is further optimized by laser annealing. The wavelength of the laser annealing is 532nm and the power density is 0.1-0.5J / cm².