High quality perovskite thick film, method of making and use thereof

Abstract

The present application relates to a kind of high-quality perovskite thick film and its preparation method and purposes, including the perovskite precursor solution of 95-105 ℃ supersaturation concentration is dropped to substrate, with different slit height scraper, with different speed is carried out multiple steps of doctoring, through specific process, it is difficult to control perovskite film thickness in prior art and the technical problem that perovskite thick film defect density is high and causes radiation detector to have higher dark current density, perovskite thick film preparation can be flexibly, conveniently, obtained with low defect density, high density, high uniformity perovskite thick film, the present application has the advantages of low cost, preparation is convenient, can be produced in large area etc., required temperature is below 200 ℃, especially doctoring and annealing process can be completed in atmospheric environment, it is conducive to industrial production.

Description

Technical Field

[0001] This invention belongs to the field of perovskite films, and particularly relates to a high-quality perovskite thick film, its preparation method, and its applications. Background Technology

[0002] Semiconductor nuclear radiation detection and imaging have immense application value in fields such as medical imaging, non-destructive testing, and security inspection. With the development of information technology, there is an urgent need for real-time high-definition digital imaging via X-ray detection; therefore, flat-panel X-ray imagers (FPXI) have emerged. Low dose, high sensitivity, and high resolution are the most important performance parameters of FPXI, and the nuclear radiation detector material is the key factor determining the performance indicators of FPXI.

[0003] Currently, flat-panel X-ray imaging is mainly divided into two types: indirect conversion FPXI and direct conversion FPXI. Compared with indirect conversion FPXI, direct conversion FPXI has a relatively simplified device structure, lower manufacturing cost, and better spatial resolution. Currently, materials used in nuclear radiation detectors include a-Se, TlBr, and CdZnTe, but these traditional materials have many disadvantages that limit their widespread application. For example, a-Se has low absorption rate for high-energy X-rays, and within a certain range above room temperature, a-Se material will locally crystallize and lose its photoelectric conversion function; TlBr is highly toxic; and the preparation temperature of CdZnTe is too high. Therefore, there is an urgent need to develop low-cost, high-performance nuclear radiation detection materials.

[0004] Solution method for organic-inorganic perovskite ABX3 (where A = CH3NH3) + (MA), HC(NH2)2 + (FA), Cs + Etc., B = Pb 2+ Sn 2+ Etc., X = Cl - ,Br - I -(etc.) meets the screening requirements for nuclear radiation semiconductor materials and is an excellent direct conversion FPXI candidate material. In 2015, Wolfgang Heiss [Yakunin,S.,Sytnyk,M.,Kriegner,D.,etc.Detection of X-ray photons by solution-processed lead halideperovskites.Nature Photonics,2015,9(7):444-U44.] et al. obtained leaf images based on MAPbI3 polycrystalline film X-ray detectors, opening the door to the application of solution-processed perovskite materials in the field of nuclear radiation imaging. At the same time, they also proposed that perovskite thick films of 10-100μm level are needed to block X-rays. However, existing perovskite film spin-coating processes have problems such as difficulty in controlling the thickness of perovskite films and difficulty in obtaining micron-sized dense perovskite thick films. The thick films prepared by existing perovskite film blade coating processes have low density due to the stacking of many grains in the cross section. As a result, there are a large number of grain boundaries and pores in the carrier migration direction, which seriously inhibits the carrier mobility. In addition, a large number of defects lead to a high dark current density in the radiation detector, which seriously hinders the commercial application of perovskite radiation detectors. Summary of the Invention

[0005] This invention addresses the aforementioned prior art by proposing a high-quality perovskite thick film, its preparation method, and its applications. It solves the technical problems of difficulty in controlling the thickness of perovskite films and the high dark current density of radiation detectors caused by the high defect density of perovskite thick films. It enables flexible and convenient preparation of perovskite thick films, resulting in perovskite thick films with low defect density, high density, and high uniformity. This invention has advantages such as low cost, convenient preparation, and large-area production capability. The required temperature is below 200℃, and in particular, the coating and annealing processes can be completed in an atmospheric environment, which is beneficial for industrial production.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for preparing a high-quality perovskite thick film, characterized by comprising the following steps:

[0008] 1) A supersaturated perovskite precursor solution at 95-105℃ is dropped onto the substrate, and the first coating is performed using a doctor blade with a slit height of less than 20μm at a coating speed of 0.8-1.2cm / s.

[0009] For the first coat, use 6-8 μL of the perovskite precursor solution per square centimeter of the substrate;

[0010] 2) Continue to add the perovskite precursor solution dropwise, and perform a second coating at a coating speed of 5-10 cm / s;

[0011] The slit height of the scraper used in the second coating is greater than or equal to the slit height of the scraper used in the first coating and less than or equal to 20 μm;

[0012] During the second coating, 1.5-2.5 μL of the perovskite precursor solution is used per square centimeter of the substrate;

[0013] 3) Repeat step 2) 4-5 times to obtain a perovskite substrate film with a dense and smooth surface;

[0014] 4) Continue to add the perovskite precursor solution dropwise, and perform the coating at a coating speed of 0.8-1.2 cm / s. Repeat this process at least once until the perovskite substrate film of the required thickness is obtained. During the process, ensure that the slit height of the doctor blade is greater than or equal to the thickness of the perovskite substrate film after the previous coating, and use 6-8 μL of the perovskite precursor solution per square centimeter of the substrate for each coating.

[0015] 5) Anneal the perovskite substrate film obtained in step 4) to obtain a high-quality perovskite thick film.

[0016] In steps 1)-4), the perovskite precursor solution is composed of APbX3, wherein A is one or more of Cs, MA or FA, and X is Br or I; the solvent of the perovskite precursor solution is a DMSO-GBL mixture with a volume ratio of 1:3 to 1:7, wherein the volume ratio does not include endpoint values.

[0017] The perovskite precursor solution is set at a supersaturated concentration of 95-105℃ to achieve higher solubility of the perovskite precursor solution before coating.

[0018] Furthermore, steps 1)-5) are all performed in an atmospheric environment;

[0019] Furthermore, the substrate is quartz glass, ITO, FTO, or NiO. x Or AZO and its doped and modified conductive glass.

[0020] Furthermore, prior to step 1), the substrate undergoes ultrasonic cleaning with deionized water, ultrasonic cleaning with acetone, ultrasonic cleaning with isopropanol, and subsequent ozone cleaning after drying with nitrogen. Ultrasonic cleaning with deionized water removes surface contaminants. Subsequent ultrasonic cleaning with acetone further removes grease and residual adhesives. Finally, ultrasonic cleaning with isopropanol removes acetone residue, and its volatile nature ensures effective removal after cleaning. Nitrogen is used to remove any remaining isopropanol from the substrate after cleaning, preventing the isopropanol containing impurities from evaporating and leaving contaminants. Finally, ozone is used to further decompose and clean any remaining organic matter on the substrate surface. Ozone treatment also increases the wettability of the perovskite precursor solution, reducing pinhole defects in perovskite thick film preparation.

[0021] Furthermore, in steps 1)-4), the surface temperature of the substrate is maintained at 110-120°C. Based on this, the solvent evaporates quickly during the coating process, allowing a uniformly sized seed crystal layer to form on the substrate surface.

[0022] Furthermore, in steps 1)-4), the surface temperature of the substrate is maintained at 115°C.

[0023] Furthermore, the supersaturation concentration of the perovskite precursor solution is 2.2-2.4 mmol / mL. This ensures that the perovskite precursor solution contains a sufficient amount of solute, which can quickly evaporate during coating to form a supersaturated state and gradually crystallize.

[0024] Furthermore, the supersaturation concentration of the perovskite precursor solution is 2.3 mmol / mL.

[0025] Furthermore, the solvent for the perovskite precursor solution is a DMSO-GBL mixture with a volume ratio of 1:5.

[0026] Furthermore, in step 5), the annealing process specifically involves placing the obtained perovskite substrate film on a hot plate at 95-100°C and heating it for 4-6 hours, followed by natural cooling. This process allows the solvent inside the perovskite substrate film to further evaporate and reduces defects inside the perovskite crystals.

[0027] Furthermore, the present invention also provides a high-quality perovskite thick film prepared by the above method.

[0028] Furthermore, the present invention also provides the use of the above-mentioned high-quality perovskite thick film in a radiation detector.

[0029] Compared with the prior art, the technical solution of this invention has the following advantages:

[0030] 1. This invention uses a DMSO (dimethyl sulfoxide)-GBL (γ-butyrolactone) mixture with a specific volume ratio of 1:3 to 1:7 (excluding endpoint values) as the solvent for the perovskite precursor solution, so that the components of the perovskite precursor form a supersaturated perovskite precursor solution at a specific temperature of 95-105℃, thereby enabling the perovskite precursor to be uniformly spread and stably precipitated during the coating process.

[0031] 2. This invention also improves the specific process of the coating process, including strictly controlling the slit height of the scraper, the amount of perovskite precursor solution used, and the coating speed for each coating under the conditions of solvent selection and temperature control of the perovskite precursor solution. This achieves the controllable acquisition of perovskite thick films with low defect density, high density, and high uniformity, resulting in a lower dark current density when applied to devices. In particular, in steps 2)-3), this invention uses a specific small amount of perovskite precursor solution and a faster coating method, repeating the process multiple times to stably and uniformly fill the unevenness and lack of density that exist after the first coating, making the subsequent preparation of perovskite thick films possible.

[0032] 3. This invention has advantages such as low cost, convenient preparation, and large-scale production. The temperature required for each step is below 200℃. In particular, the coating and annealing processes can be completed in an atmospheric environment, which is conducive to industrial production. Attached Figure Description

[0033] Figure 1 This shows a comparison of different solvent concentration gradients at room temperature.

[0034] Figure 2 Cs was prepared by mixing DMSO and GBL (1:5) at a ratio of 2.3 mmol / mL. 0.05 MA 0.60 FA 0.35 PbI3 perovskite precursor solution gradient temperature dissolution diagram;

[0035] Figure 3 Cs heated to 95℃ 0.05 MA 0.60 FA 0.35 Comparison of PbI3 perovskite precursor solution and corresponding scraping coating.

[0036] Figure 4 Cs obtained in Example 1 0.05 MA 0.60 FA 0.35 SEM characterization of PbI3 perovskite thick film;

[0037] Figure 5 Cs obtained in Example 2 0.05 MA 0.60 FA0.35 SEM characterization of PbI3 perovskite thick film;

[0038] Figure 6 Cs obtained in Example 3 0.05 MA 0.60 FA 0.35 SEM characterization of PbI3 perovskite thick film;

[0039] Figure 7 Cs obtained for Comparative Example 1 0.05 MA 0.60 FA 0.35 SEM characterization of PbI3 perovskite thick film;

[0040] Figure 8 Cs obtained for Comparative Example 2 0.05 MA 0.60 FA 0.35 SEM characterization of PbI3 perovskite thick film;

[0041] Figure 9 The Cs with a thickness of approximately 30 μm prepared in this invention 0.05 MA 0.60 FA 0.35 SEM characterization of PbI3 perovskite thick film;

[0042] Figure 10 This is a test diagram of the hole defect density of perovskite device A;

[0043] Figure 11 This is a graph showing the electronic defect density of perovskite device B.

[0044] Figure 12 This is a schematic diagram of the structure of radiation detector C;

[0045] Figure 13 The image shows the dark current density of radiation detector C. Detailed Implementation

[0046] The principles and features of the present invention are described below with reference to embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified, specific conditions or manufacturer-recommended conditions should be followed in the embodiments. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0047] Figure 1 The comparison of different solvent concentration gradients at room temperature is shown. Specifically, Figure 1 Cs from left to right 0.05 MA 0.60 FA 0.35The solvents and concentrations of the PbI3 perovskite precursor solutions were: DMSO+GBL (1:5) 2.3 mmol / mL, DMSO+GBL (1:5) 1.8 mmol / mL, DMSO+GBL (1:5) 1.2 mmol / mL, DMSO+DMF (1:5) 2.3 mmol / mL, DMSO+DMF (1:5) 1.8 mmol / mL, and DMSO+DMF (1:5) 1.2 mmol / mL. Figure 1 It can be seen that the solvent combination of DMSO+GBL is more likely to achieve supersaturation concentration than the solvent combination of DMSO+DMF.

[0048] Figure 2 The concentration of Cs in a DMSO+GBL (1:5) solution of 2.3 mmol / mL was shown. 0.05 MA 0.60 FA 0.35 A temperature gradient dissolution diagram of PbI3 perovskite precursor solution, specifically... Figure 2 The temperatures from left to right are 50℃, 70℃, 80℃, 90℃, and 95℃. Figure 2 It is known that when the temperature is above 95℃, the perovskite precursor solution can form a better supersaturated solution.

[0049] Figure 3 The image shows Cs heated to 95°C. 0.05 MA 0.60 FA 0.35 The comparison of the PbI3 perovskite precursor solution followed by the corresponding scraping coating method is shown below. The scraping coating method is based on the perovskite thick film preparation steps in Example 1. Specifically, Figure 3 Cs from left to right 0.05 MA 0.60 FA 0.35 The solvents and concentrations of the PbI3 perovskite precursor solutions were: DMSO+GBL (1:5) 2.3 mmol / mL, DMSO+GBL (1:5) 1.8 mmol / mL, DMSO+GBL (1:5) 1.2 mmol / mL, DMSO+DMF (1:5) 2.3 mmol / mL, DMSO+DMF (1:5) 1.8 mmol / mL, and DMSO+DMF (1:5) 1.2 mmol / mL. Figure 3 It can be seen that the solvent combination of DMSO+GBL exhibits better scraping effect under supersaturated conditions compared to the solvent combination of DMSO+DMF.

[0050] Example 1:

[0051] Preparation of Cs with a thickness of 5 μm 0.05 MA 0.60 FA0.35 PbI3 perovskite thick film:

[0052] Preparation: Prepare a supersaturated perovskite precursor solution. Weigh CsI, MAI, FAI, and PbI2 according to their chemical formula ratios. Place the weighed reagents in a reagent bottle and add solvent at a ratio of DMSO:GBL of 1:5 to prepare a solution with a concentration of 2.3 mmol / mL. Heat and stir at 100°C for 1 hour until completely dissolved.

[0053] ITO glass substrates measuring 1.4cm × 1.4cm were sequentially sonicated with deionized water for 15 minutes, acetone for 15 minutes, and isopropanol for 15 minutes. After drying with a nitrogen gun, they were ozone cleaned for 20 minutes and set aside. The cleaned ITO glass was fixed on a copper coating mold and placed on a heating stage. The ITO glass surface temperature was heated to 115°C. The prepared perovskite precursor solution was heated to 100°C until it became a clear solution.

[0054] Specific steps for preparing perovskite thick films:

[0055] 1) Add 14 μL of the perovskite precursor solution to the ITO glass substrate, and use a doctor blade with a 10 μm slit height to perform the first coating at a coating speed of 1 cm / s.

[0056] 2) Continue to drop 4 μL of the perovskite precursor solution onto the ITO glass substrate, and use a doctor blade with a 20 μm slit height to perform a second coating at a coating speed of 5 cm / s.

[0057] 3) Repeat step 2) 5 times to obtain a perovskite substrate film with a dense and flat surface;

[0058] 4) Continue to drop 14 μL of the perovskite precursor solution onto the ITO glass substrate, and use a doctor blade with a 50 μm slit height to coat the substrate at a speed of 1 cm / s; repeat once.

[0059] 5) The perovskite substrate film prepared in step 4) was placed on a 95°C heating stage for 6 hours and then allowed to cool naturally to obtain the Cs of Example 1. 0.05 MA 0.60 FA 0.35 PbI3 perovskite thick film;

[0060] Steps 1)-5) are all carried out in an atmospheric environment.

[0061] Figure 4 Cs obtained in Example 1 0.05 MA 0.60 FA 0.35SEM characterization images of the PbI3 perovskite thick film. As can be seen from the images, the Cs obtained in Example 1... 0.05 MA 0.60 FA 0.35 The PbI3 perovskite thick film has a dense, uniform, and pore-free surface with a thickness of about 5 μm and no obvious interfaces or defects in its cross-section.

[0062] Example 2:

[0063] Preparation of Cs with a thickness on the order of 10 μm 0.05 MA 0.60 FA 0.35 PbI3 perovskite thick film:

[0064] The preparation work is the same as in Example 1;

[0065] Specific steps for preparing perovskite thick films:

[0066] 1) Add 14 μL of the perovskite precursor solution to the ITO glass substrate, and use a doctor blade with a 10 μm slit height to perform the first coating at a coating speed of 1 cm / s.

[0067] 2) Continue to drop 4 μL of the perovskite precursor solution onto the ITO glass substrate, and use a doctor blade with a 20 μm slit height to perform a second coating at a coating speed of 5 cm / s.

[0068] 3) Repeat step 2) 5 times to obtain a perovskite substrate film with a dense and flat surface;

[0069] 4) Continue to add 14 μL of the perovskite precursor solution to the ITO glass substrate, using a doctor blade with a 50 μm slit height and a coating speed of 1 cm / s; repeat once; continue to add 14 μL of the perovskite precursor solution to the ITO glass substrate, using a doctor blade with a 100 μm slit height and a coating speed of 1 cm / s; repeat once.

[0070] 5) The perovskite substrate film prepared in step 4) was placed on a 95°C heating stage for 6 hours and then allowed to cool naturally to obtain the Cs of Example 2. 0.05 MA 0.60 FA 0.35 PbI3 perovskite thick film;

[0071] Steps 1)-5) are all carried out in an atmospheric environment.

[0072] Figure 5 Cs obtained in Example 2 0.05 MA 0.60 FA 0.35 SEM characterization images of the PbI3 perovskite thick film. As can be seen from the images, the Cs obtained in Example 2...0.05 MA 0.60 FA 0.35 The PbI3 perovskite thick film has a dense, uniform, and pore-free surface with a thickness of approximately 11.5 μm and no obvious interfaces or defects in its cross-section.

[0073] Example 3:

[0074] Preparation of Cs with a thickness of 15 μm 0.05 MA 0.60 FA 0.35 PbI3 perovskite thick film:

[0075] The preparation work is the same as in Example 1;

[0076] Specific steps for preparing perovskite thick films:

[0077] 1) Add 14 μL of the perovskite precursor solution to the ITO glass substrate, and use a doctor blade with a 10 μm slit height to perform the first coating at a coating speed of 1 cm / s.

[0078] 2) Continue to drop 4 μL of the perovskite precursor solution onto the ITO glass substrate, and use a doctor blade with a 20 μm slit height to perform a second coating at a coating speed of 5 cm / s.

[0079] 3) Repeat step 2) 5 times to obtain a perovskite substrate film with a dense and flat surface;

[0080] 4) Continue to add 14 μL of the perovskite precursor solution to the ITO glass substrate, using a doctor blade with a 50 μm slit height and a coating speed of 1 cm / s; repeat once. Continue to add 14 μL of the perovskite precursor solution to the ITO glass substrate, using a doctor blade with a 100 μm slit height and a coating speed of 1 cm / s; repeat once. Continue to add 14 μL of the perovskite precursor solution to the ITO glass substrate, using a doctor blade with a 150 μm slit height and a coating speed of 1 cm / s; repeat once.

[0081] 5) The perovskite substrate film prepared in step 4) was placed on a 95°C heating stage for 6 hours and then allowed to cool naturally to obtain the Cs of Example 3. 0.05 MA 0.60 FA 0.35 PbI3 perovskite thick film;

[0082] Steps 1)-5) are all carried out in an atmospheric environment.

[0083] Figure 6 Cs obtained in Example 3 0.05 MA 0.60 FA 0.35SEM characterization images of the PbI3 perovskite thick film. As can be seen from the images, the Cs obtained in Example 3... 0.05 MA 0.60 FA 0.35 The PbI3 perovskite thick film has a dense, uniform, and pore-free surface with a thickness of about 15 μm and no obvious interfaces or defects in its cross-section.

[0084] Comparative Example 1:

[0085] The preparation work differs from that of Example 1 in that: in Comparative Example 1, solvent was added at a ratio of DMSO:GBL of 1:3;

[0086] The specific preparation steps for the perovskite thick film are the same as in Example 3.

[0087] Figure 7 Cs obtained for Comparative Example 1 0.05 MA 0.60 FA 0.35 SEM characterization images of PbI3 perovskite thick films. From the images, it can be seen that the Cs obtained in Comparative Example 1... 0.05 MA 0.60 FA 0.35 The PbI3 perovskite thick film, about 15 μm thick, has low uniformity. In some parts of the cross section, a dense thick film was not completely formed, and in the middle part of the thick film, a dense crystal was not completely formed.

[0088] Comparative Example 2:

[0089] The preparation work differs from that of Example 1 in that: in Comparative Example 2, solvent was added at a ratio of DMSO:GBL of 1:7;

[0090] The specific preparation steps of the perovskite thick film differ from those in Example 3 in that: Step 4) of Comparative Example 2 is as follows: 14 μL of the perovskite precursor solution is added dropwise to the ITO glass substrate, and a doctor blade with a 50 μm slit height is used for coating at a speed of 1 cm / s; this is repeated once; 14 μL of the perovskite precursor solution is added dropwise to the ITO glass substrate, and a doctor blade with a 100 μm slit height is used for coating at a speed of 1 cm / s; this is repeated once; 14 μL of the perovskite precursor solution is added dropwise to the ITO glass substrate, and a doctor blade with a 150 μm slit height is used for coating at a speed of 1 cm / s; this is repeated once; 14 μL of the perovskite precursor solution is added dropwise to the ITO glass substrate, and a doctor blade with a 300 μm slit height is used for coating at a speed of 1 cm / s; this is repeated once.

[0091] Figure 8 Cs obtained for Comparative Example 2 0.05 MA 0.60 FA 0.35SEM characterization images of PbI3 perovskite thick films. From the images, it can be seen that the Cs obtained in Comparative Example 2... 0.05 MA 0.60 FA 0.35 The PbI3 perovskite thick film, about 30 μm thick, has large surface undulations, low uniformity of crystal growth size, and the cross-section does not form a uniform thick film with good density.

[0092] Performance testing:

[0093] Hole defect density test:

[0094] Perovskite Device A: Glass Substrate / ITO / NiO x / Cs 0.05 MA 0.60 FA 0.35 PbI3 / Au, where Cs 0.05 MA 0.60 FA 0.35 PbI3 is a Cs layer with a thickness of approximately 30 μm prepared using this invention. 0.05 MA 0.60 FA 0.35 PbI3 perovskite thick film (SEM image of the perovskite thick film is shown below) Figure 9 (As shown).

[0095] Device testing: IV curves were tested under dark conditions, and the logarithm of the x and y axes of the IV curves was obtained. Figure 10 The hole defect density was determined to be 2.03 × 10⁻⁶ using the space charge-limited current method. 12 cm -3 .

[0096] Electron defect density test:

[0097] Perovskite Device B: Glass Substrate / FTO / Cs 0.05 MA 0.60 FA 0.35 PbI3 / PC 61 BM / Al, where Cs 0.05 MA 0.60 FA 0.35 PbI3 is a Cs layer with a thickness of approximately 30 μm prepared using this invention. 0.05 MA 0.60 FA 0.35 PbI3 perovskite thick film (SEM image of the perovskite thick film is shown below) Figure 9 (As shown).

[0098] Device testing: IV curves were tested under dark conditions, and the logarithm of the x and y axes of the IV curves was obtained. Figure 11 The electron defect density was determined to be 1.03 × 10⁻⁶ according to the space charge-limited current method.12 cm -3 .

[0099] The aforementioned hole defect density and electron defect density are both above 10. 12 cm -3 In comparison, the hole and electron defect densities of traditional spin-coated perovskite films are both around 10⁻⁶. 14 -10 16 cm -3 class.

[0100] Dark current density test:

[0101] Constructing a radiation detector C: such as Figure 12 As shown, it includes a substrate layer 1, a first electrode 2, a hole transport layer 3, an X-ray absorption layer 4, an electron transport layer 5, and a second electrode 6; wherein, the substrate layer 1 is glass, the first electrode 2 is ITO, and the hole transport layer 3 is NiO. x The X-ray absorbing layer 4 is a Cs layer with a thickness of approximately 30 μm prepared using the present invention. 0.05 MA 0.60 FA 0.35 PbI3 perovskite thick film (SEM image of the perovskite thick film is shown below) Figure 9 As shown), electron transport layer 5 is PC. 61 BM, the second electrode 6 is Au.

[0102] Device testing: Under X-ray irradiation conditions (Tungsten target X-ray source Optima 97008, Oxford Instruments X-Ray Technology, Inc.), the photoresponse curve was measured, and the test results are as follows. Figure 13 As shown, at 0.24 Gy air s -1 Under dose and bias conditions of 1V, the perovskite thick-film radiation detector C exhibited good photoelectric response stability and a high sensitivity / dark current density ratio of 1.07 × 10⁻⁶. 5 μC Gyair -1 cm -1 A -1 / 2 and a relatively low dark current density of 3.00 nA / cm² -2 .

[0103] Based on the above specific embodiments and test experiments, compared with the prior art, the present invention has the following beneficial effects:

[0104] 1. This invention uses a DMSO (dimethyl sulfoxide)-GBL (γ-butyrolactone) mixture with a specific volume ratio of 1:3 to 1:7 (excluding endpoint values) as the solvent for the perovskite precursor solution, so that the components of the perovskite precursor form a supersaturated perovskite precursor solution at a specific temperature of 95-105℃, thereby enabling the perovskite precursor to be uniformly spread and stably precipitated during the coating process.

[0105] 2. This invention also improves the specific process of the coating process, including strictly controlling the slit height of the scraper, the amount of perovskite precursor solution used, and the coating speed for each coating under the conditions of solvent selection and temperature control of the perovskite precursor solution. This achieves the controllable acquisition of perovskite thick films with low defect density, high density, and high uniformity, resulting in a lower dark current density when applied to devices. In particular, in steps 2)-3), this invention uses a specific small amount of perovskite precursor solution and a faster coating method, repeating the process multiple times to stably and uniformly fill the unevenness and lack of density that exist after the first coating, making the subsequent preparation of perovskite thick films possible.

[0106] 3. This invention has advantages such as low cost, convenient preparation, and large-scale production. The temperature required for each step is below 200℃. In particular, the coating and annealing processes can be completed in an atmospheric environment, which is conducive to industrial production.

[0107] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A method for preparing a high-quality perovskite thick film, characterized in that, Includes the following steps: 1) A supersaturated perovskite precursor solution at 95-105℃ is dropped onto the substrate, and the first coating is performed using a doctor blade with a slit height of less than 20μm at a coating speed of 0.8-1.2cm / s. For the first coat, use 6-8 μL of the perovskite precursor solution per square centimeter of the substrate; 2) Continue to add the perovskite precursor solution dropwise, and perform a second coating at a coating speed of 5-10 cm / s; The slit height of the scraper used in the second coating is greater than or equal to the slit height of the scraper used in the first coating and less than or equal to 20 μm; During the second coating, 1.5-2.5 μL of the perovskite precursor solution is used per square centimeter of the substrate; 3) Repeat step 2) 4-5 times to obtain a perovskite substrate film with a dense and smooth surface; 4) Continue to add the perovskite precursor solution dropwise, and perform the coating at a coating speed of 0.8-1.2 cm / s. Repeat this process at least once until the perovskite substrate film of the required thickness is obtained. During the process, ensure that the slit height of the doctor blade is greater than or equal to the thickness of the perovskite substrate film after the previous coating, and use 6-8 μL of the perovskite precursor solution per square centimeter of the substrate for each coating. 5) Anneal the perovskite substrate film obtained in step 4) to obtain a high-quality perovskite thick film. In steps 1)-4), the perovskite precursor solution is composed of APbX3, wherein A is one or more of Cs, MA or FA, and X is Br or I; the solvent of the perovskite precursor solution is a DMSO-GBL mixture with a volume ratio of 1:3 to 1:7, wherein the volume ratio does not include endpoint values.

2. The method according to claim 1, characterized in that, The substrate is quartz glass, ITO, FTO, or NiO. x Or AZO and its doped and modified conductive glass.

3. The method according to claim 1, characterized in that, Before step 1), the substrate is further subjected to ultrasonic cleaning with deionized water, ultrasonic cleaning with acetone, ultrasonic cleaning with isopropanol, and ozone cleaning after being dried with nitrogen.

4. The method according to claim 1, characterized in that, In steps 1)-4), the surface temperature of the substrate is maintained at 110-120℃.

5. The method according to claim 1, characterized in that, In steps 1)-4), the surface temperature of the substrate is maintained at 115°C.

6. The method according to claim 1, characterized in that, The supersaturation concentration of the perovskite precursor solution is 2.2-2.4 mmol / mL.

7. The method according to claim 1, characterized in that, The supersaturation concentration of the perovskite precursor solution was 2.3 mmol / mL.

8. The method according to claim 1, characterized in that, The solvent for the perovskite precursor solution is a DMSO-GBL mixture with a volume ratio of 1:

5.

9. A high-quality perovskite thick film prepared by the method according to any one of claims 1-8.

10. Use of the high-quality perovskite thick film as described in claim 9 in a radiation detector.

Images