X-ray detector for in-situ growth of large-area perovskite single crystals on thin film transistor based on solution method and preparation method of X-ray detector
By growing a large area of perovskite single crystal in situ on the TFT, the problem of poor contact interface between the perovskite single crystal and the TFT was solved by using a glass pad and solvent evaporation growth method, thus achieving uniform dark current and excellent detection performance of the X-ray detector.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JILIN UNIVERSITY
- Filing Date
- 2026-02-04
- Publication Date
- 2026-05-01
AI Technical Summary
Existing technologies make it difficult to fabricate large-area perovskite single crystals on thin-film transistors (TFTs), resulting in non-uniform device performance and poor contact interfaces, which affects the overall performance and stability of X-ray detectors.
Large-area perovskite single crystals were grown in situ on TFTs using a solution method. The vertical growth of thin perovskite single crystals was restricted by glass pads. Combined with slow solvent evaporation and reverse temperature growth, a strong interface connection was formed between the PTAA hole transport layer and the TFT to prepare MAPbI3 thin perovskite single crystals.
Uniform connection between large-area perovskite single crystals and TFT back arrays was achieved, improving the dark current uniformity and detection performance of X-ray detectors, and enhancing the stability and performance consistency of the devices.
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Figure CN121968980A_ABST
Abstract
Description
An X-ray detector based on in-situ growth of large-area perovskite single crystals on thin-film transistors using a solution method and its fabrication method. Technical Field
[0001] This invention belongs to the field of X-ray detector technology, specifically relating to an X-ray detector based on in-situ growth of a large area of perovskite single crystal on a thin-film transistor (TFT) using a solution method and its fabrication method. Background Technology
[0002] Lead-iodine-based perovskite materials have attracted widespread attention and research in the field of high-performance X-ray detection due to their advantages such as high absorption coefficient, long charge carrier diffusion distance, and good solution processability. In recent years, perovskite X-ray detectors based on polycrystalline thin films and single-crystal structures have emerged continuously, achieving significant progress in several key performance parameters such as sensitivity, detection limit, and response speed. Some indicators have reached or even surpassed the level of existing commercial detectors. In particular, single-crystal perovskites, due to their low defect density and few grain boundaries, can significantly suppress nonradiative recombination of charge carriers, thus exhibiting significantly better X-ray detection performance than polycrystalline thin films. They are considered the most promising material system for driving the commercialization of this technology.
[0003] However, the fabrication size of perovskite single crystals is currently limited to the millimeter scale due to insufficient solvent mass transfer capabilities, making it difficult to meet the basic requirements for integration with large-area, commercial thin-film transistor (TFT) backplanes. Assembling multiple single crystals introduces performance inhomogeneities between them, and the difficulty in forming a good contact interface between the assembled single crystal and the TFT severely affects the detector's dark current and X-ray response. These factors significantly impact the overall performance and stability of the device, restricting its practical application in large-area imaging and integrated detection systems. Summary of the Invention
[0004] The purpose of this invention is to provide an X-ray detector based on in-situ growth of a large area perovskite single crystal on a TFT using a solution method and its preparation method.
[0005] This invention is achieved through the following technical solution:
[0006] An X-ray detector based on in-situ growth of a large-area perovskite single crystal on a thin-film transistor using a solution method is disclosed. The detector comprises a TFT back array, a hole transport layer fabricated on the TFT back array, a MAPbI3 perovskite thin single crystal fabricated on the hole transport layer, and a top electrode fabricated on the MAPbI3 perovskite thin single crystal. The hole transport layer is poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) with a thickness of 200–400 nm, and the MAPbI3 perovskite thin single crystal has a thickness of 0.5 mm–2.0 mm.
[0007] The method for fabricating an X-ray detector based on in-situ growth of a large-area perovskite single crystal on a thin-film transistor using a solution method, as described in this invention, comprises the following steps:
[0008] 1) Preparation of MAPbI3 solution: Dissolve methylamine iodine and lead iodide in a 1:1 molar ratio in a mixed solution of 2-methoxyethanol and acetonitrile to prepare a perovskite precursor solution with a methylamine lead iodine concentration of 1.2~1.5M. Then stir at room temperature for 2~5h until all solutes are dissolved to obtain MAPbI3 solution; wherein, the volume ratio of 2-methoxyethanol to acetonitrile is 4~5:1.
[0009] 2) Preparation of PTAA solution: Mix PTAA and toluene at a ratio of 2 mg: 0.5~2.0 mL, and stir at room temperature for 3~6 h until all the solute is dissolved to obtain PTAA solution;
[0010] 3) Cleaning the TFT back array plate, glass pads and flat substrate: Use acetone, ethanol and isopropanol to ultrasonically clean the TFT back array plate glass pads and flat substrate in sequence, and blow them dry with a nitrogen gun. Then clean the TFT back array plate with ultraviolet ozone for 8~10 minutes.
[0011] 4) Preparation of hole transport layer: On the TFT back array plate and flat substrate obtained in step 3), spin-coat PTAA solution for 30-50s at a rotation speed of 3000-5000rpm and an acceleration of 1500-2500rpm, and then anneal on a hot stage at 90-110℃ for 8-15 minutes, thereby preparing hole transport layers with a thickness of 200-400 nm on the surface of the TFT back array plate and flat substrate respectively.
[0012] 5) Preparation of seed crystals: Take 1.5~3.0 mL of the MAPbI3 solution obtained in step 1) and start heating at 70~75℃, with a heating rate of 0.5~1.5℃ / 30 minutes, until black perovskite seed crystals are produced in the solution.
[0013] 6) Preparation of thin single crystal growth device: In a glass container, place the hole transport layer of the TFT back array obtained in step 4) facing upwards, place a glass pad in the non-active region of the hole transport layer of the TFT back array, and place a perovskite seed crystal obtained in step 5) in the center of the active region. Then, cover the glass pad with the flat substrate obtained in step 4), and make the hole transport layer of the flat substrate face the direction of the TFT back array.
[0014] 7) Growth of single crystals: Immerse the thin single crystal growth apparatus obtained in step 6) into the MAPbI3 solution obtained in step 1), and then start heating at a rate of 0.4~0.6℃ every 5 hours under sealed conditions and at 65~68℃. Use the slow solvent evaporation and inverted temperature growth method to grow MAPbI3 perovskite thin single crystals for 30~35h.
[0015] 8) Annealing treatment: After taking out the TFT back array plate / PTAA / MAPbI3 / PTAA / flat substrate structure obtained in step 7), anneal it on a hot stage at 60~65℃ for 8~15min to remove the flat substrate along with the hole transport layer prepared on its surface, and obtain a large-area smooth surface in-situ grown MAPbI3 perovskite thin single crystal covering the entire active area on the hole transport layer of the TFT back array plate; the thickness of the MAPbI3 perovskite thin single crystal is equal to the thickness of the glass pad, which is 0.5mm~2mm;
[0016] 9) Prepare a top electrode (a carbon electrode with a thickness of 100~500μm or a gold electrode with a thickness of 20~100nm) on the MAPbI3 perovskite thin single crystal obtained in step 8) to obtain the X-ray detector based on in-situ growth of a large area perovskite single crystal on a TFT as described in this invention.
[0017] Compared with existing technologies, the beneficial effects of this invention are reflected in:
[0018] This invention utilizes glass spacers as spacers to limit the vertical growth thickness of perovskite thin single crystals. Taking advantage of the moderate saturated vapor pressure and strong mass transfer capability of the binary solvent combination of 2-methoxyethanol and acetonitrile, the perovskite thin single crystal growth covering the entire active region can be completed at 65-68°C, compatible with TFT processes, through slow solvent evaporation and a reverse-temperature growth process. A PTAA hole transport layer connects the MAPbI3 perovskite thin single crystal to the TFT, ensuring a strong interface connection between the in-situ grown MAPbI3 perovskite thin single crystal and the TFT back array. Subsequently, a top electrode is fabricated, completing the in-situ growth of a large-area perovskite single crystal on the TFT for an X-ray detector. Compared with existing technologies, this invention has the following advantages:
[0019] (1) Combining the slow solvent evaporation method, the reverse temperature growth method, and the seed crystal growth epitaxial method: By utilizing vertical space constraints, the thickness of the perovskite thin single crystal in the vertical direction is limited, and the solvent evaporation rate is controlled, so that the single crystal growth rate and the solvent evaporation rate at the corresponding temperature are balanced. Combining the advantages of these two growth methods, the single crystal has good quality, smooth and regular morphology, fast growth rate, and the growth temperature is compatible with the TFT back array.
[0020] (2) The X-ray detector with large-area perovskite single crystal grown in situ on the TFT obtained by this preparation method can achieve excellent uniformity of dark current for each pixel and obtain excellent X-ray detection performance. Attached Figure Description
[0021] Figure 1 is a schematic diagram of the process for preparing MAPbI3 perovskite thin single crystals in Examples 1-4 of the present invention;
[0022] Figure 2 is a schematic diagram showing the size information of the commercial TFTs used in Embodiments 1-4 of the present invention;
[0023] Figure 3 is an optical photograph of MAPbI3 thin single crystal grown in situ on TFT in Embodiment 1 of the present invention;
[0024] Figure 4 is a statistical chart of dark current data for each pixel of the X-ray detector obtained by in-situ growth of MAPbI3 thin single crystal on TFT in Embodiment 1 of the present invention.
[0025] Figure 5 is a schematic diagram of the structure of the X-ray detector obtained by in-situ growth of MAPbI3 thin single crystal on TFT in Examples 1-4 of the present invention.
[0026] Figure 6 is a statistical chart of the X-ray current data of each pixel of the X-ray detector obtained by in-situ growth of MAPbI3 thin single crystal on TFT in Embodiment 1 of the present invention. Detailed Implementation
[0027] The following describes in detail, with reference to the accompanying drawings, the specific implementation scheme of the X-ray detector with large-area perovskite single crystal grown in situ on a TFT according to the present invention.
[0028] The present invention provides a method for fabricating an X-ray detector based on a binary solvent engineering of 2-methoxyethanol and acetonitrile to grow a large area perovskite single crystal on a TFT in situ, as shown in Figure 1. For specific steps, please refer to the various embodiments.
[0029] Example 1
[0030] 1) Preparation of MAPbI3 solution: Dissolve methylamine iodine (1033.5 mg, 6.5 mmol) and lead iodide (2996.5 mg, 6.5 mmol) in a 1:1 molar ratio in a mixed solution of 2-methoxyethanol (4 mL) and acetonitrile (1 mL) to prepare a perovskite precursor solution with a methylamine lead iodine concentration of 1.3 M. Then stir at room temperature for 3 h until all solutes are dissolved to obtain MAPbI3 solution;
[0031] 2) Preparation of PTAA solution: Mix 10 mg of PTAA with 5 mL of toluene and stir for 5 hours until the solute is completely dissolved to obtain PTAA solution;
[0032] 3) Clean the TFT back array plate, four 1mm thick glass pads and flat substrate: Use acetone, ethanol and isopropanol to ultrasonically clean the TFT back array plate glass pads and flat substrate in sequence, and blow them dry with a nitrogen gun. Then clean the TFT back array plate with ultraviolet ozone for 10 minutes.
[0033] 4) Preparation of hole transport layer: On the TFT back array and flat substrate obtained in step 3), spin-coat 150 μL of PTAA solution for 40s at a rotation speed of 4000 rpm and an acceleration of 2000 rpm, and then anneal on a hot stage at 100℃ for 10 minutes, thereby preparing a hole transport layer with a thickness of about 300 nm on the surface of the TFT back array and flat substrate respectively.
[0034] 5) Preparation of seed crystals: Take 2 mL of the MAPbI3 solution obtained in step 1) and start heating at 75°C at a heating rate of 1.0°C / 30 minutes until black perovskite seed crystals are produced in the solution.
[0035] 6) Preparation of thin single crystal growth device: In a glass container, place the hole transport layer of the TFT back array obtained in step 4) facing upwards, place a glass pad in the non-active region of the hole transport layer of the TFT back array, and place a perovskite seed crystal obtained in step 5) in the center of the active region. Then, cover the glass pad with the flat substrate obtained in step 4), and make the hole transport layer of the flat substrate face the direction of the TFT back array.
[0036] 7) Growth of single crystal: Immerse the thin single crystal growth apparatus obtained in step 6) into the MAPbI3 solution obtained in step 1), and then start heating at a rate of 0.5°C every 5 hours under sealed conditions and at 65°C, using the slow solvent evaporation and inverted temperature growth method to grow MAPbI3 thin single crystals for 35 hours.
[0037] 8) Annealing treatment: After taking out the TFT back array plate / PTAA / MAPbI3 / PTAA / flat substrate structure obtained in step 7), anneal it on a hot stage at 65°C for 10 min. Remove the flat substrate along with the hole transport layer prepared on its surface to obtain a large area of smooth surface in situ grown on the hole transport layer of the TFT back array plate with a thickness of 1 mm covering the entire active area.
[0038] 9) Coat a carbon top electrode (approximately 100 μm thick) onto the TFT / PTAA / MAPbI3 structure obtained in step 8) to obtain the X-ray detector based on in-situ growth of a large-area perovskite single crystal on a TFT as described in this invention.
[0039] Example 2
[0040] 1) Preparation of MAPbI3 solution: Dissolve methylamine iodine (1033.5 mg, 6.5 mmol) and lead iodide (2996.5 mg, 6.5 mmol) in a 1:1 molar ratio in a mixed solution of 2-methoxyethanol (4 mL) and acetonitrile (1 mL) to prepare a perovskite precursor solution with a methylamine lead iodine concentration of 1.3 M. Then stir at room temperature for 3 h until all solutes are dissolved to obtain MAPbI3 solution;
[0041] 2) Preparation of PTAA solution: Weigh 10 mg of PTAA powder, put it into a glass bottle, add 5 mL of toluene, and add a magnetic stir bar; place the glass bottle on a magnetic stirring table and stir for 5 min at room temperature until the solute is completely dissolved to obtain PTAA solution.
[0042] 3) Clean the TFT back array plate, four 1.5mm thick glass pads and flat substrate: Use acetone, ethanol and isopropanol to ultrasonically clean the TFT back array plate glass pads and flat substrate in sequence, and blow them dry with a nitrogen gun. Then clean the TFT back array plate with ultraviolet ozone for 10 minutes.
[0043] 4) Preparation of hole transport layer: On the TFT back array and flat substrate obtained in step 3), spin-coat 150 μL of PTAA solution for 40s at a rotation speed of 4000 rpm and an acceleration of 2000 rpm, and then anneal on a hot stage at 100℃ for 10 minutes, thereby preparing a hole transport layer with a thickness of about 300 nm on the surface of the TFT back array and flat substrate respectively.
[0044] 5) Preparation of seed crystals: Take 2 mL of the MAPbI3 solution obtained in step 1) and start heating at 75°C at a heating rate of 1.0°C / 30 minutes until black perovskite seed crystals are produced in the solution.
[0045] 6) Preparation of thin single crystal growth device: In a glass container, place the hole transport layer of the TFT back array obtained in step 4) facing upwards, place a glass pad in the non-active region of the hole transport layer of the TFT back array, and place a perovskite seed crystal obtained in step 5) in the center of the active region. Then, cover the glass pad with the flat substrate obtained in step 4), and make the hole transport layer of the flat substrate face the direction of the TFT back array.
[0046] 7) Growth of single crystal: Immerse the thin single crystal growth apparatus obtained in step 6) into the MAPbI3 solution obtained in step 1), and then, under sealed conditions, start heating at 65°C at a rate of 0.5°C every 5 hours, and grow MAPbI3 thin single crystals for 35 hours using the slow solvent evaporation and inverted temperature growth method.
[0047] 8) Annealing treatment: After taking out the TFT back array plate / PTAA / MAPbI3 / PTAA / flat substrate structure obtained in step 7), anneal it on a hot stage at 65°C for 10 min. Remove the flat substrate along with the hole transport layer prepared on its surface to obtain a large area of smooth surface in situ grown on the hole transport layer of the TFT back array plate with a thickness of 1.5 mm covering the entire active area.
[0048] 9) Coat a carbon top electrode (approximately 100 μm thick) onto the TFT / PTAA / MAPbI3 structure obtained in step 8) to obtain the X-ray detector based on in-situ growth of a large-area perovskite single crystal on a TFT as described in this invention.
[0049] Example 3
[0050] 1) Preparation of MAPbI3 solution: Dissolve methylamine iodine (1033.5 mg, 6.5 mmol) and lead iodide (2996.5 mg, 6.5 mmol) in a 1:1 molar ratio in a mixed solution of 2-methoxyethanol (4 mL) and acetonitrile (1 mL) to prepare a perovskite precursor solution with a methylamine lead iodine concentration of 1.3 M. Then stir at room temperature for 3 h until all solutes are dissolved to obtain MAPbI3 solution;
[0051] 2) Preparation of PTAA solution: Weigh 10 mg of PTAA powder, put it into a glass bottle, add 5 mL of toluene, and add a magnetic stir bar; place the glass bottle on a magnetic stirring table and stir for 5 min at room temperature until the solute is completely dissolved to obtain PTAA solution.
[0052] 3) Clean the TFT back array plate, four 2 mm thick glass pads and flat substrate: Use acetone, ethanol and isopropanol to ultrasonically clean the TFT back array plate glass pads and flat substrate in sequence, and blow them dry with a nitrogen gun. Then clean the TFT back array plate with ultraviolet ozone for 10 min.
[0053] 4) Preparation of hole transport layer: On the TFT back array and flat substrate obtained in step 3), spin-coat 150 μL of PTAA solution for 40s at a rotation speed of 4000 rpm and an acceleration of 2000 rpm, and then anneal on a hot stage at 100℃ for 10 minutes, thereby preparing a hole transport layer with a thickness of about 300 nm on the surface of the TFT back array and flat substrate respectively.
[0054] 5) Preparation of seed crystals: Take 2 mL of the MAPbI3 solution obtained in step 1) and start heating at 75°C at a heating rate of 1.0°C / 30 minutes until black perovskite seed crystals are produced in the solution.
[0055] 6) Preparation of thin single crystal growth device: In a glass container, place the hole transport layer of the TFT back array obtained in step 4) facing upwards, place a glass pad in the non-active region of the hole transport layer of the TFT back array, and place a perovskite seed crystal obtained in step 5) in the center of the active region. Then, cover the glass pad with the flat substrate obtained in step 4), and make the hole transport layer of the flat substrate face the direction of the TFT back array.
[0056] 7) Growth of single crystal: Immerse the thin single crystal growth apparatus obtained in step 6) into the MAPbI3 solution obtained in step 1), and then, under sealed conditions, start heating at 65°C at a rate of 0.5°C every 5 hours, and grow MAPbI3 thin single crystals for 35 hours using the slow solvent evaporation and inverted temperature growth method.
[0057] 8) Annealing treatment: After taking out the TFT back array plate / PTAA / MAPbI3 / PTAA / flat substrate structure obtained in step 7), anneal it on a hot stage at 65°C for 10 min. Remove the flat substrate along with the hole transport layer prepared on its surface to obtain a large area of smooth surface in situ grown on the hole transport layer of the TFT back array plate with a thickness of 2 mm covering the entire active area.
[0058] 9) Coat a carbon top electrode (approximately 100 μm thick) onto the TFT / PTAA / MAPbI3 structure obtained in step 8) to obtain the X-ray detector based on in-situ growth of a large-area perovskite single crystal on a TFT as described in this invention.
[0059] Example 4
[0060] 1) Preparation of MAPbI3 solution: Dissolve methylamine iodine (1033.5 mg, 6.5 mmol) and lead iodide (2996.5 mg, 6.5 mmol) in a 1:1 molar ratio in a mixed solution of 2-methoxyethanol (4 mL) and acetonitrile (1 mL) to prepare a perovskite precursor solution with a methylamine lead iodine concentration of 1.3 M. Then stir at room temperature for 3 h until all solutes are dissolved to obtain MAPbI3 solution;
[0061] 2) Preparation of PTAA solution: Weigh 10 mg of PTAA powder, put it into a glass bottle, add 5 mL of toluene, and add a magnetic stir bar; place the glass bottle on a magnetic stirring table and stir for 5 min at room temperature until the solute is completely dissolved to obtain PTAA solution.
[0062] 3) Clean the TFT back array plate, four 0.5mm thick glass pads and flat substrate: Use acetone, ethanol and isopropanol to ultrasonically clean the TFT back array plate glass pads and flat substrate in sequence, and blow them dry with a nitrogen gun. Then clean the TFT back array plate with ultraviolet ozone for 10 minutes.
[0063] 4) Preparation of hole transport layer: On the TFT back array and flat substrate obtained in step 3), spin-coat 150 μL of PTAA solution for 40s at a rotation speed of 4000 rpm and an acceleration of 2000 rpm, and then anneal on a hot stage at 100℃ for 10 minutes, thereby preparing a hole transport layer with a thickness of about 300 nm on the surface of the TFT back array and flat substrate respectively.
[0064] 5) Preparation of seed crystals: Take 2 mL of the MAPbI3 solution obtained in step 1) and start heating at 75°C at a heating rate of 1.0°C / 30 minutes until black perovskite seed crystals are produced in the solution.
[0065] 6) Preparation of thin single crystal growth device: In a glass container, place the hole transport layer of the TFT back array obtained in step 4) facing upwards, place a glass pad in the non-active region of the hole transport layer of the TFT back array, and place a perovskite seed crystal obtained in step 5) in the center of the active region. Then, cover the glass pad with the flat substrate obtained in step 4), and make the hole transport layer of the flat substrate face the direction of the TFT back array.
[0066] 7) Growth of single crystal: Immerse the thin single crystal growth apparatus obtained in step 6) into the MAPbI3 solution obtained in step 1), and then, under sealed conditions, start heating at 65°C at a rate of 0.5°C every 5 hours, and grow MAPbI3 thin single crystals for 35 hours using the slow solvent evaporation and inverted temperature growth method.
[0067] 8) Annealing treatment: After taking out the TFT back array plate / PTAA / MAPbI3 / PTAA / flat substrate structure obtained in step 7), anneal it on a hot stage at 65°C for 10 min. Remove the flat substrate along with the hole transport layer prepared on its surface to obtain a large area of smooth surface in situ grown on the hole transport layer of the TFT back array plate with a thickness of 0.5 mm covering the entire active area.
[0068] 9) Coat a carbon top electrode (approximately 100 μm thick) onto the TFT / PTAA / MAPbI3 structure obtained in step 8) to obtain the X-ray detector based on in-situ growth of a large-area perovskite single crystal on a TFT as described in this invention.
[0069] In Examples 1-4, the thickness of the MAPbI3 thin single crystal grown on the TFT varied with the thickness of the glass pad. Excessive thickness of the thin single crystal would affect its X-ray performance, while excessive thinness would make it difficult to fabricate a large-area crystal to cover the entire active region of the TFT. Subsequent experiments were based on the 1mm thick MAPbI3 thin single crystal from Example 1.
[0070] Figure 1 shows a schematic flowchart of the preparation of MAPbI3 perovskite thin single crystals in Examples 1-4. First, the hole transport layer of the TFT back array is placed upward in a glass container, and a glass pad is placed in the non-active area of the hole transport layer of the TFT back array. A perovskite seed crystal obtained in step 5) is placed in the center of the active area. Then, the flat substrate obtained in step 4) is placed on the glass pad, with the hole transport layer of the flat substrate facing the TFT back array. Then, the MAPbI3 solution obtained in step 1) is added. Then, under a sealed environment, the MAPbI3 thin single crystal is grown by slow solvent evaporation and reverse temperature growth method until the MAPbI3 thin single crystal covers the entire active area of the TFT back array. After the whole structure is removed, it is annealed on a hot stage for 10 minutes. The flat substrate and the hole transport layer prepared on its surface are peeled off to obtain a large-area, smooth MAPbI3 thin single crystal grown in situ on the hole transport layer of the TFT back array, covering the entire active area.
[0071] Figure 2 shows a schematic diagram of the size information of the commercial TFT used in Examples 1 to 4. The length and width of the active area of the TFT are both 1.2 mm, and it is divided into 12 rows * 12 columns with an interval of 1 mm, with a total of 144 pixels.
[0072] Figure 3 shows an optical photograph of the in-situ growth of MAPbI3 thin single crystal on the TFT in Example 1. The area of the MAPbI3 thin single crystal covers the entire active region of the TFT.
[0073] Figure 4 shows the dark current data statistics of each pixel of the X-ray detector obtained by in-situ growth of MAPbI3 thin single crystal on TFT in Example 1. A positive bias of 1V is applied from the top electrode (drain) to the column readout (source) on the TFT, and a positive bias of 10V is applied from the row scan (gate) on the TFT to the drain. The current value of the drain of the pixel corresponding to the TFT row and column is read. It can be seen that the X-ray detector prepared by in-situ growth of perovskite single crystal on TFT as shown in Figure 2 has a dark current difference of no more than half an order of magnitude in each pixel, and follows a normal distribution characteristic with good dark current uniformity.
[0074] Figure 5 shows a schematic diagram of the structure of the X-ray detector obtained by in-situ growth of MAPbI3 thin single crystals on TFTs in Examples 1-4.
[0075] In Example 1, each pixel of the X-ray detector obtained by in-situ growth of a MAPbI3 thin single crystal on a TFT has a density of 123 nGy / s. -1At the radiation dose rate, a positive bias of 1V is applied from the drain to the source on the TFT, and a positive bias of 10V is applied from the gate to the drain on the TFT. The X-ray current data statistics of the drain current values of the corresponding pixels in the TFT rows and columns are shown in Figure 6. The horizontal axis represents the distribution of X-ray current values, and the vertical axis represents the number of pixels. It can be seen that the X-ray detector prepared by in-situ growth of perovskite single crystals on the TFT shown in Figure 2 has a X-ray current difference of no more than half an order of magnitude in each pixel, and follows a normal distribution characteristic, showing good X-ray current uniformity.
[0076] The above embodiments are merely illustrative examples of the technical solutions of the present invention. The X-ray detector and its fabrication method based on in-situ growth of large-area perovskite single crystals on TFTs using a solution method, as described in the present invention, are not limited to the contents described in the above embodiments, but are defined by the scope of the claims. Any modifications, supplements, equivalent substitutions, or improvements made by those skilled in the art within the spirit and principles of this invention should be included within the protection scope of this invention.
Claims
1. A method for fabricating an X-ray detector based on in-situ growth of a large-area perovskite single crystal on a thin-film transistor using a solution method, comprising the following steps: 1) Preparing a MAPbI3 solution: Dissolving methylamine iodine and lead iodide in a 1:1 molar ratio in a mixed solution of 2-methoxyethanol and acetonitrile to prepare a perovskite precursor solution with a methylamine lead iodine concentration of 1.2~1.5M, then stirring at room temperature for 2~5 hours until all solutes are dissolved to obtain a MAPbI3 solution; 2) Preparing a PTAA solution: Mixing PTAA and toluene in a ratio of 2mg:0.5~2.0mL, stirring at room temperature for 3~6 hours until all solutes are dissolved to obtain a PTAA solution; wherein, PTAA is poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]; 3) Cleaning the TFT back array plate, glass pad, and flat substrate: The TFT back array plate glass pad and flat substrate are ultrasonically cleaned sequentially with acetone, ethanol, and isopropanol, and dried with a nitrogen gun. Then, the TFT back array plate is cleaned with ultraviolet ozone for 8-10 minutes; where TFT is a thin film transistor; 4) Preparing the hole transport layer: PTA is spin-coated onto the TFT back array plate and flat substrate obtained in step 3) under the conditions of rotation speed of 3000-5000 rpm and acceleration of 1500-2500 rpm. Solution A is heated for 30-50 seconds, then annealed on a hot stage at 90-110℃ for 8-15 minutes to prepare hole transport layers on the TFT back array and flat substrate surfaces respectively; 5) Seed crystal preparation: 1.5-3.0 mL of the MAPbI3 solution obtained in step 1) is heated at 70-75℃ at a rate of 0.5-1.5℃ / 30 minutes until black perovskite seed crystals are produced in the solution; 6) Thin single crystal growth apparatus preparation: In a glass container, the hole transport layer of the TFT back array obtained in step 4) is placed facing upwards, and the hole transport layer of the TFT back array is... Place a glass pad in the non-active region and place a perovskite seed crystal obtained in step 5) in the center of the active region. Then, cover the glass pad with the flat substrate obtained in step 4), and make the hole transport layer of the flat substrate face the TFT back array plate; 7) Grow single crystal: Immerse the thin single crystal growth device obtained in step 6) into the MAPbI3 solution obtained in step 1), and then start heating at a rate of 0.4~0.6℃ every 5 hours under sealed conditions and 65~68℃, using the slow solvent evaporation and reverse temperature growth method to grow MAPbI3 perovskite thin single crystal for 30~35h; 8 Annealing treatment: After taking out the TFT back array plate / PTAA / MAPbI3 / PTAA / flat substrate structure obtained in step 7), anneal it on a hot stage at 60~65℃ for 8~15min to remove the flat substrate along with the hole transport layer prepared on its surface, and obtain a large-area smooth surface in-situ grown MAPbI3 perovskite thin single crystal covering the entire active area on the hole transport layer of the TFT back array plate; 9) Prepare the top electrode on the MAPbI3 perovskite thin single crystal obtained in step 8), thereby obtaining the X-ray detector based on the in-situ growth of a large area perovskite single crystal on TFT as described in this invention.
2. The method for fabricating an X-ray detector based on in-situ growth of a large-area perovskite single crystal on a thin-film transistor using a solution method as described in claim 1, characterized in that: In step 1), the volume ratio of 2-methoxyethanol to acetonitrile is 4~5:
1.
3. The method for fabricating an X-ray detector based on in-situ growth of a large-area perovskite single crystal on a thin-film transistor using a solution method as described in claim 1, characterized in that: In step 3), the flattened substrate is a glass substrate, a silicon wafer substrate, or a sapphire substrate.
4. The method for fabricating an X-ray detector based on in-situ growth of a large-area perovskite single crystal on a thin-film transistor using a solution method as described in claim 1, characterized in that: In step 8), the thickness of the MAPbI3 perovskite thin single crystal is equal to the thickness of the glass pad, which is 0.5mm~2mm.
5. The method for fabricating an X-ray detector based on in-situ growth of a large-area perovskite single crystal on a thin-film transistor using a solution method as described in claim 1, characterized in that: In step 9), the top electrode is a carbon electrode with a thickness of 100~500μm or a gold electrode with a thickness of 20~100nm.
6. An X-ray detector based on in-situ growth of a large-area perovskite single crystal on a thin-film transistor using a solution method, characterized in that: It is prepared by the preparation method described in any one of claims 1 to 5.