A flexible two-dimensional tin-based perovskite photodetector and its preparation method

Abstract

The present invention provides a flexible two-dimensional tin-based perovskite photodetector and a preparation method thereof. The flexible two-dimensional tin-based perovskite photodetector of the present invention comprises a flexible silicon wafer, a metal back electrode, a two-dimensional tin-based perovskite film, a transparent conductive electrode, and a polymethyl methacrylate film; wherein the polymethyl methacrylate film can effectively block water vapor and oxygen in the air, preventing Sn from 2+ Oxidized to Sn 4+ , thereby improving the environmental stability and service life of the device; the light detector of the present invention is suitable for the fields of wearable devices, flexible displays and smart sensors, has a wide spectral response capability, and can perform efficient photoelectric conversion from ultraviolet to infrared bands.

Description

Technical Field

[0001] The present invention relates to the technical field of perovskite photodetectors, and in particular to a flexible two-dimensional tin-based perovskite photodetector and a preparation method thereof. Background Art

[0002] With the growing demand for smarter and more portable electronic devices, flexible optoelectronic devices, as a next-generation technology, show tremendous potential for application. However, conventional photodetectors are mostly based on rigid silicon materials, which cannot meet the mechanical flexibility and bendability requirements of flexible electronic devices. Furthermore, despite the excellent optoelectronic properties of lead-based perovskite materials, their toxicity and environmental pollution issues limit their use in large-scale production and applications. Therefore, the development of environmentally friendly, safe, and high-performance flexible photodetectors has become an important direction of current technological development.

[0003] Two-dimensional perovskite materials are a type of perovskite material with a specific layered structure. Compared with traditional three-dimensional perovskites, they have unique layered properties. In two-dimensional perovskites, the inorganic layer of the perovskite (usually a metal halide, such as lead, tin and other cations and halogen anions composed of BX4 2 -layers are separated by organic molecules, forming an organic-inorganic hybrid layered structure. Two-dimensional perovskite materials such as PEA2SnCl4 are lead-free and environmentally friendly materials with large band gaps, excellent light absorption properties and adjustable spectral responses, especially in the ultraviolet and blue light bands. In addition, the two-dimensional layered structure of this material enables it to maintain high-efficiency optoelectronic performance while having good mechanical flexibility and environmental stability, making it suitable for application in flexible optoelectronic devices. However, the charge transport performance of two-dimensional perovskite materials is poor, and tin-based materials are easily oxidized, which poses certain challenges to the stability of the device.

[0004] Based on the defects of the current two-dimensional perovskite materials used in photodetectors, it is necessary to improve them. Summary of the Invention

[0005] In light of this, the present invention provides a flexible photodetector based on a flexible silicon wafer and a two-dimensional tin-based perovskite, and its preparation method, addressing the issues of insufficient mechanical flexibility, poor environmental stability, and insufficient spectral response faced by current flexible optoelectronic devices. By combining the high light absorption efficiency of the two-dimensional tin-based perovskite material with the excellent charge transfer properties of the flexible silicon wafer, this photodetector provides efficient broad-spectrum light detection, particularly in the ultraviolet and visible light ranges, with excellent performance. This invention is particularly suitable for use in smart wearable devices, flexible displays, and high-sensitivity photodetectors.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a flexible two-dimensional tin-based perovskite photodetector, comprising:

[0008] Flexible silicon wafers;

[0009] A metal back electrode is located on one surface of the flexible silicon wafer;

[0010] a two-dimensional tin-based perovskite film located on a surface of the flexible silicon wafer away from the metal back electrode, the two-dimensional tin-based perovskite film being located in the middle of the flexible silicon wafer, and two sides of the flexible silicon wafer being not covered by the two-dimensional tin-based perovskite film;

[0011] A transparent conductive electrode is located on the surface of the two-dimensional tin-based perovskite film away from the flexible silicon wafer, with both sides of the transparent conductive electrode extending toward the area of ​​the flexible silicon wafer not covered by the two-dimensional tin-based perovskite film and being bonded to the flexible silicon wafer;

[0012] The polymethyl methacrylate film is located on a surface of the transparent conductive electrode away from the flexible silicon wafer and corresponding to the two-dimensional tin-based perovskite film.

[0013] Preferably, the material of the metal back electrode includes any one of silver, copper and aluminum;

[0014] And / or, the chemical formula of the two-dimensional tin-based perovskite film is A2BX4;

[0015] Wherein, A is an organic cation, B is a metal cation, and X is a halogen anion;

[0016] Preferably, the organic cation includes any one of phenylethylamine cation, butylamine cation, ethylamine cation, isopropylamine cation, propylamine cation, cyclohexylamine cation, benzylamine cation, methoxyethylamine cation, and chloromethylamine cation;

[0017] The metal cation is Sn 2+ or Pb 2+ ;

[0018] The halogen anions include Cl - Br - , I - Any of;

[0019] And / or, the transparent conductive electrode comprises any one of indium tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide and proton-doped tin oxide;

[0020] And / or, the thickness of the flexible silicon sheet is 30 to 50 μm;

[0021] and / or, the thickness of the metal back electrode is 100 to 200 nm;

[0022] and / or, the thickness of the two-dimensional tin-based perovskite film is 500 to 1000 nm;

[0023] and / or, the thickness of the transparent conductive electrode is 100 to 200 nm;

[0024] And / or, the polymethyl methacrylate film has a thickness of 5 to 10 μm.

[0025] In a second aspect, the present invention further provides a method for preparing the flexible two-dimensional tin-based perovskite photodetector, comprising the following steps:

[0026] A metal back electrode is prepared on the side of the flexible silicon wafer;

[0027] A two-dimensional tin-based perovskite film is prepared on a surface of the flexible silicon wafer away from the metal back electrode, wherein the two-dimensional tin-based perovskite film is located in the middle of the flexible silicon wafer, and two sides of the flexible silicon wafer are not covered by the two-dimensional tin-based perovskite film;

[0028] A transparent conductive electrode is prepared on the surface of the two-dimensional tin-based perovskite film, with both sides of the transparent conductive electrode extending toward the area of ​​the flexible silicon wafer not covered by the two-dimensional tin-based perovskite film and being bonded to the flexible silicon wafer;

[0029] A polymethyl methacrylate film is prepared on the surface of the transparent conductive electrode corresponding to the two-dimensional tin-based perovskite film.

[0030] Preferably, a silicon wafer with a thickness of 150 to 160 μm is placed in an alkaline solution and subjected to heat treatment to reduce its thickness to 30 to 50 μm, thereby obtaining a flexible silicon wafer.

[0031] Preferably, a metal back electrode is prepared on the surface of a flexible silicon wafer by magnetron sputtering, wherein the process parameters controlled during magnetron sputtering are: sputtering power 50-150W, argon gas pressure 0.1-0.5Pa, and time 10-30min.

[0032] Preferably, the chemical formula of the two-dimensional tin-based perovskite film is PEA2SnCl4;

[0033] A two-dimensional tin-based perovskite film is prepared on a surface of the flexible silicon wafer away from the metal back electrode, specifically comprising the following steps:

[0034] Add SnCl2 and PEACl to the solvent and mix to obtain a precursor solution;

[0035] The precursor solution is coated on the middle portion of the surface of the flexible silicon wafer away from the metal back electrode, and after reaction, annealing is performed to obtain a two-dimensional tin-based perovskite film.

[0036] Preferably, a transparent conductive electrode is prepared on the surface of a two-dimensional tin-based perovskite film by reactive plasma deposition, wherein the deposition rate is

[0037] Preferably, a polymethyl methacrylate film is prepared on the surface of the transparent conductive electrode corresponding to the two-dimensional tin-based perovskite film, specifically comprising the following steps:

[0038] adding polymethyl methacrylate to chlorobenzene to obtain a polymethyl methacrylate solution having a concentration of 0.1-0.5 g / mL;

[0039] The polymethyl methacrylate solution is coated on the surface of the transparent conductive electrode corresponding to the two-dimensional tin-based perovskite film, and then annealed at 200-300° C. for 10-20 minutes to obtain the polymethyl methacrylate film.

[0040] Preferably, a silicon wafer having a thickness of 150 to 160 μm is placed in an alkaline solution, and in the step of heat treatment, the alkaline solution includes at least one of a NaOH solution and a KOH solution;

[0041] The molar concentration of the alkali solution is 0.5 to 5 M;

[0042] The heating treatment temperature is 70-90°C and the time is 40-50 minutes.

[0043] Preferably, the precursor solution is coated on the middle portion of the surface of the flexible silicon wafer away from the metal back electrode. After the reaction, in the annealing step, the annealing temperature is 95-105° C. and the time is 25-35 minutes.

[0044] In the step of adding SnCl2 and PEACl to a solvent and mixing to obtain a precursor solution, the molar ratio of SnCl2 and PEACl is 1:2; and the solvent includes at least one of γ-butyrolactone, N-methylpyrrolidone, dimethylformamide, dimethyl sulfoxide, deuterated chloroform, 1,3-dimethylpropylene urea, xylene, n-butanol, dimethylacetamide, propylene glycol ether and cyclohexanone.

[0045] The flexible two-dimensional tin-based perovskite photodetector of the present invention has the following advantages over the prior art:

[0046] 1. The flexible two-dimensional tin-based perovskite photodetector of the present invention comprises a flexible silicon wafer, a metal back electrode, a two-dimensional tin-based perovskite film, a transparent conductive electrode, and a polymethyl methacrylate film; wherein the polymethyl methacrylate film can effectively block water vapor and oxygen in the air and prevent Sn 2+ Oxidized to Sn 4+, thereby improving the environmental stability and service life of the device; the light detector of the present invention is suitable for the fields of wearable devices, flexible displays and smart sensors, has a wide spectral response capability, and can perform efficient photoelectric conversion from ultraviolet to infrared bands.

[0047] 2. The flexible two-dimensional tin-based perovskite photodetector of the present invention has high sensitivity and wide spectral response: The photodetector of the present invention has high photoelectric conversion efficiency in both the ultraviolet and visible light bands, making it suitable for a variety of optoelectronic applications. The light response range is 200-1100nm; the responsivity of the two-dimensional tin-based perovskite flexible photodetector in the range of 200-370nm is 2-3 times that of ordinary flexible crystalline silicon.

[0048] 3. The flexible two-dimensional tin-based perovskite photodetector of the present invention has excellent flexibility: the use of thinned flexible silicon wafers enables the photodetector to function normally under complex mechanical deformation, making it suitable for wearable devices and flexible electronic products. The photodetector of the present invention has a bendable curvature of 3 to 5 cm, and after 10,000 bends, the performance of the photodetector can still maintain 30% of its initial performance.

[0049] 4. The flexible two-dimensional tin-based perovskite photodetector of the present invention has excellent environmental stability: through the PMMA encapsulation process, the photodetector maintains high stability in air and humidity conditions, extending its service life. Through the device encapsulation process, the operating time of the flexible device can be increased from a few hours to 10,000 hours;

[0050] 5. The flexible two-dimensional tin-based perovskite photodetector of the present invention is an environmentally friendly lead-free material: the two-dimensional tin-based perovskite material uses tin instead of the traditional lead element, which meets environmental protection requirements and has good photoelectric properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0052] Figure 1 Schematic diagram of the structure of the flexible two-dimensional tin-based perovskite photodetector of the present invention;

[0053] Figure 2 is the UV-visible absorption spectrum of the two-dimensional tin-based perovskite film (PEA2SnCl4) prepared in Example 1;

[0054] Figure 3is the X-ray diffraction (XRD) pattern of the two-dimensional tin-based perovskite film (PEA2SnCl4) prepared in Example 1;

[0055] Figure 4 is the X-ray photoelectron spectroscopy curve of the Sn element in the two-dimensional tin-based perovskite film (PEA2SnCl4) prepared in Example 1;

[0056] Figure 5 Comparison of EQE curves of the photodetector prepared in Comparative Example 1 and the flexible two-dimensional tin-based perovskite photodetector prepared in Comparative Example 1;

[0057] Figure 6 Comparison of the photoresponsivity curves of the photodetector prepared in Comparative Example 1 and the flexible two-dimensional tin-based perovskite photodetector prepared in Comparative Example 1;

[0058] Figure 7 This is the photoresponsivity curve of the flexible two-dimensional tin-based perovskite photodetector prepared in Example 1 within 0-0.3s;

[0059] Figure 8 This is the photoresponsivity curve of the flexible two-dimensional tin-based perovskite photodetector prepared in Example 1 within 0-0.02s;

[0060] Figure 9 The responsivity of the flexible two-dimensional tin-based perovskite photodetector prepared in Example 1 to 530nm green light after being bent 180 degrees in the forward direction and 180 degrees in the reverse direction;

[0061] Figure 10 The flexible two-dimensional tin-based perovskite photodetector prepared in Example 1 was bent 90 degrees in the forward and reverse directions 10,000 times to measure its photoresponse curve under 300 nm ultraviolet light.

[0062] Figure 11 The flexible two-dimensional tin-based perovskite photodetector prepared in Example 1 was tested for a change curve of its photoresponsivity under 300nm ultraviolet light after working in air for 10,000 hours. DETAILED DESCRIPTION

[0063] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0064] It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments. In addition, in the description of this application, the term "including" means "including but not limited to". Various embodiments of the present invention may be in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be understood as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the numbered ranges, such as 1, 2, 3, 4, 5 and 6, regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited numbers (fractions or integers) within the indicated range.

[0065] The embodiment of the present application provides a flexible two-dimensional tin-based perovskite photodetector, such as Figure 1 Shown, including:

[0066] Flexible silicon wafer 1;

[0067] A metal back electrode 2 is located on one surface of the flexible silicon wafer 1;

[0068] The two-dimensional tin-based perovskite film 3 is located on the surface of the flexible silicon wafer 1 away from the metal back electrode 2. The two-dimensional tin-based perovskite film 3 is located in the middle of the flexible silicon wafer 1, and the two sides of the flexible silicon wafer 1 are not covered by the two-dimensional tin-based perovskite film 3;

[0069] The transparent conductive electrode 4 is located on the surface of the two-dimensional tin-based perovskite film 3 away from the flexible silicon wafer 1, and both sides of the transparent conductive electrode 4 extend toward the area of ​​the flexible silicon wafer not covered by the two-dimensional tin-based perovskite film 3 and adhere to the flexible silicon wafer 1;

[0070] The polymethyl methacrylate film 5 is located on the surface of the transparent conductive electrode 4 away from the flexible silicon wafer 1 and corresponding to the two-dimensional tin-based perovskite film 5 .

[0071] The flexible two-dimensional tin-based perovskite photodetector of the present invention comprises a flexible silicon wafer 1, a metal back electrode 2, a two-dimensional tin-based perovskite film 3, a transparent conductive electrode 4, and a polymethyl methacrylate film 5; the metal back electrode 2 and the two-dimensional tin-based perovskite film 3 are respectively located on opposite surfaces of the flexible silicon wafer 1; wherein the polymethyl methacrylate film 5 can effectively block water vapor and oxygen in the air, preventing Sn 2+ Oxidized to Sn 4+ , thereby improving the environmental stability and service life of the device. The light detector of the present invention is suitable for the fields of wearable devices, flexible displays and smart sensors, has a wide spectral response capability, and can perform efficient photoelectric conversion from ultraviolet to infrared bands.

[0072] Flexible silicon wafers have become an important material for flexible optoelectronic devices due to their excellent charge transfer performance and mature process technology. Combining two-dimensional tin-based perovskites with flexible silicon wafers can fully utilize the advantages of both, retaining the high electron mobility and wide spectral response range of the silicon wafer, and expanding the spectral response range of the device through the efficient light absorption performance of the perovskite layer, especially in the ultraviolet and blue light bands. Through this material combination design, the photoelectric conversion efficiency and mechanical flexibility of the flexible light detector can be effectively improved. The flexible light detector based on flexible silicon wafers and two-dimensional tin-based perovskites of the present invention overcomes the problems of environmental unfriendliness, insufficient spectral response, poor device flexibility, etc. in the prior art, and realizes efficient wide-spectrum light detection, excellent mechanical flexibility and long-term environmental stability, and is suitable for a variety of emerging application scenarios such as smart wearables and flexible displays.

[0073] In some embodiments, the material of the metal back electrode 2 includes any one of silver, copper, and aluminum.

[0074] In some embodiments, the chemical formula of the two-dimensional tin-based perovskite film is A2BX4;

[0075] A is an organic cation, B is a metal cation, and X is a halogen anion.

[0076] In some embodiments, the organic cations include: Phenylethylammonium cation (PEA + ), referred to as: PEA; Butylammonium cation (BA + ), referred to as BA; Ethylammonium cation (EA + ), referred to as EA; Isopropylammonium cation (Isopropylammonium, IPA+), referred to as IPA; Propylammonium cation (Propylammonium, PA + ), referred to as PA; Cyclohexylammonium cation (Cyclohexylammonium, CHA + ), referred to as CHA; benzylamine cation (Benzylammonium, BZA + ), referred to as BZA; Methoxyethylammonium cation (Methoxyethylammonium, MEA + ), referred to as: MEA; Chloromethylammonium cation (Chloromethylammonium, CMA + ), abbreviated as: CMA.

[0077] In some embodiments, the metal cation is Sn 2+ or Pb 2+ .

[0078] In some embodiments, the halide anion comprises Cl - Br - , I - Any of .

[0079] In this structure, the inorganic layer (such as BX4 2- layer) is covered by the organic layer (A + The inorganic layers interact with each other via weak van der Waals forces, while the organic layers are flexible organic chains, giving the material flexibility and good environmental stability.

[0080] In some embodiments, the transparent conductive electrode includes any one of indium tin oxide (ITO), aluminum-doped zinc oxide (AZO), and gallium-doped zinc oxide (GZO).

[0081] In some embodiments, the thickness of the flexible silicon wafer 1 is 30 to 50 μm;

[0082] In some embodiments, the thickness of the metal back electrode 2 is 100 to 200 nm;

[0083] In some embodiments, the thickness of the two-dimensional tin-based perovskite film 3 is 500 to 1000 nm;

[0084] In some embodiments, the thickness of the transparent conductive electrode 4 is 100 to 200 nm;

[0085] In some embodiments, the thickness of the polymethyl methacrylate film 5 is 5-10 μm.

[0086] Based on the same inventive concept, the present invention also provides a method for preparing the above-mentioned flexible two-dimensional tin-based perovskite photodetector, comprising the following steps:

[0087] S1. Prepare a metal back electrode on the side of the flexible silicon wafer;

[0088] S2. Prepare a two-dimensional tin-based perovskite film on a surface of the flexible silicon wafer away from the metal back electrode, wherein the two-dimensional tin-based perovskite film is located in the middle of the flexible silicon wafer, and two sides of the flexible silicon wafer are not covered by the two-dimensional tin-based perovskite film;

[0089] S3. A transparent conductive electrode is prepared on the surface of the two-dimensional tin-based perovskite film, with both sides of the transparent conductive electrode extending toward the area of ​​the flexible silicon wafer not covered by the two-dimensional tin-based perovskite film and being bonded to the flexible silicon wafer;

[0090] S4. A polymethyl methacrylate film is prepared on the surface of the transparent conductive electrode corresponding to the two-dimensional tin-based perovskite film.

[0091] In some embodiments, a silicon wafer having a thickness of 150-160 μm is placed in an alkaline solution, heated, and then chemically etched to reduce its thickness to 30-50 μm, thereby obtaining a flexible silicon wafer. This step ensures thickness uniformity and mechanical stability of the silicon wafer by precisely controlling the heating temperature and etching time.

[0092] In some embodiments, magnetron sputtering is used to deposit a metal back electrode on the surface of a flexible silicon wafer. The metal back electrode can be made of silver, copper, or aluminum, with the specific choice adjusted based on the device application scenario and conductivity requirements. By adjusting sputtering parameters, such as sputtering power of 50 to 150 W, argon pressure of 0.1 to 0.5 Pa, and time of 10 to 30 minutes, a uniform and dense metal back electrode layer is formed.

[0093] In some embodiments, the two-dimensional tin-based perovskite film has a chemical formula of PEA2SnCl4;

[0094] A two-dimensional tin-based perovskite film is prepared on a surface of a flexible silicon wafer away from a metal back electrode, specifically comprising the following steps:

[0095] Add SnCl2 and PEACl (chemical formula C6H5CH2CH2NH3Cl(PEACl), phenylethylammonium chloride) to a solvent and mix to obtain a precursor solution;

[0096] The precursor solution is coated on the middle of the surface of the flexible silicon wafer away from the metal back electrode, reacted at room temperature (25°C), and annealed to obtain a two-dimensional tin-based perovskite film.

[0097] Specifically, a confined growth technique is used to deposit a two-dimensional tin-based perovskite (PEA2SnCl4) thin film in the center of a flexible silicon wafer, away from the metal back electrode surface. This step involves uniformly coating a precursor solution (such as SnCl2 and PEACl) on a designated area of ​​the flexible silicon wafer and performing a low-temperature annealing process to form a perovskite film with a well-defined crystal structure. Confined growth allows for precise control of the film's thickness and grain size, ensuring enhanced optoelectronic performance.

[0098] In some embodiments, a transparent conductive electrode is prepared on the surface of a two-dimensional tin-based perovskite film using a reactive plasma deposition method, wherein the deposition rate is

[0099] In some embodiments, a transparent conductive electrode is deposited on a two-dimensional tin-based perovskite film using reactive plasma deposition (RPD) technology. The electrode material is aluminum-doped zinc oxide (AZO). AZO, as a transparent conductive layer, has high electrical conductivity and optical transparency, which can ensure efficient charge collection performance of the device while ensuring the light incident efficiency. The specific preparation process of aluminum-doped zinc oxide (AZO) is to place a block of 99.9% pure aluminum-doped zinc oxide (AZO) with a diameter of 4-10mm into a crucible in the center of the RPD, then close the RPD hatch and evacuate to 10 -5 -10 -7 Pa; then 30-200sccm of argon (Ar) was introduced into the RPD chamber, and a starting current of 25-35A and a starting voltage of 300-500V were used to excite the plasma and sputter AZO. The deposition rate was

[0100] In some embodiments, a polymethyl methacrylate film is prepared on the surface of the transparent conductive electrode corresponding to the two-dimensional tin-based perovskite film, specifically comprising the following steps:

[0101] adding polymethyl methacrylate to chlorobenzene to obtain a polymethyl methacrylate solution having a concentration of 0.1-0.5 g / mL;

[0102] The polymethyl methacrylate solution is coated on the surface of the transparent conductive electrode corresponding to the two-dimensional tin-based perovskite film, and then annealed at 200-300° C. for 10-20 minutes to obtain the polymethyl methacrylate film.

[0103] In the above embodiment, in order to prevent the two-dimensional tin-based perovskite film from being oxidized in the air, the present invention adopts a pixel encapsulation method; on the two-dimensional tin-based perovskite film, a PMMA (polymethyl methacrylate) solution (concentration range is 0.1-0.5g / mL) dissolved in chlorobenzene is applied to the surface of the perovskite film by titration, and then annealing is performed to form a dense and transparent PMMA film. This encapsulation layer can effectively block water vapor and oxygen in the air, preventing Sn from 2+ Oxidized to Sn 4+ , thereby improving the environmental stability and service life of the device while keeping the AZO wire external.

[0104] In some embodiments, a silicon wafer having a thickness of 150 to 160 μm is placed in an alkaline solution, and in the step of heat treatment, the alkaline solution includes at least one of a NaOH solution and a KOH solution;

[0105] The molar concentration of the alkali solution is 0.5 to 5 M;

[0106] The heating treatment temperature is 70-90°C and the time is 40-50 minutes.

[0107] In some embodiments, the precursor solution is coated on the middle portion of the surface of the flexible silicon wafer away from the metal back electrode. After the reaction, in the annealing step, the annealing temperature is 95 to 105° C. and the time is 25 to 35 minutes.

[0108] In the step of adding SnCl2 and PEACl to a solvent and mixing to obtain a precursor solution, the molar ratio of SnCl2 and PEACl is 1:2; and the solvent includes at least one of γ-butyrolactone, N-methylpyrrolidone, dimethylformamide, dimethyl sulfoxide, deuterated chloroform, 1,3-dimethylpropylene urea, xylene, n-butanol, dimethylacetamide, propylene glycol ether and cyclohexanone.

[0109] In some embodiments, before forming a two-dimensional tin-based perovskite film on the surface of a flexible silicon wafer, the flexible silicon wafer is cut using a laser or diamond cutting tool into long strips with a controllable size of 6 cm x 1 cm (i.e., 6 cm in length and 1 cm in width). This cutting process requires precise control of the cutting tool's movement trajectory and speed to ensure that the edges of the flexible silicon wafer are neat and free of cracks.

[0110] The flexible two-dimensional tin-based perovskite photodetector prepared by the present invention has the following advantages:

[0111] 1. High sensitivity and wide spectral response: The photodetector of this invention has high photoelectric conversion efficiency in both the ultraviolet and visible light bands, making it suitable for a variety of optoelectronic applications. The photoresponse range is 200-1100nm; the responsivity of the two-dimensional tin-based perovskite flexible photodetector in the range of 200-370nm is 2-3 times that of ordinary flexible crystalline silicon.

[0112] 2. Excellent flexibility: The use of thinned flexible silicon wafers enables the photodetector to function normally under complex mechanical deformation, making it suitable for wearable devices and flexible electronic products. The photodetector of this invention has a bendable curvature of 3 to 5 cm and can maintain 30% of its initial performance after 10,000 bends.

[0113] 3. Excellent environmental stability: Through the PMMA packaging process, the light detector maintains high stability under air and humidity conditions, extending its service life. Through the device packaging process, the working time of the flexible device can be increased from a few hours to 10,000 hours;

[0114] 4. Environmentally friendly lead-free materials: Two-dimensional tin-based perovskite materials use tin instead of traditional lead elements, which meets environmental protection requirements and has good photoelectric properties.

[0115] The flexible two-dimensional tin-based perovskite photodetector and its preparation method of the present application are further described below with specific examples. This section further illustrates the content of the present invention in conjunction with specific examples, but should not be understood as limiting the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0116] Example 1

[0117] The embodiment of the present application provides a flexible two-dimensional tin-based perovskite photodetector, comprising:

[0118] Flexible silicon wafers;

[0119] A metal back electrode is located on one surface of the flexible silicon wafer;

[0120] The two-dimensional tin-based perovskite film is located on the surface of the flexible silicon wafer away from the metal back electrode. The two-dimensional tin-based perovskite film is located in the middle of the flexible silicon wafer, and the two sides of the flexible silicon wafer are not covered by the two-dimensional tin-based perovskite film.

[0121] A transparent conductive electrode is located on a surface of the flexible silicon wafer away from the two-dimensional tin-based perovskite film, with both sides of the transparent conductive electrode extending toward an area of ​​the flexible silicon wafer not covered by the two-dimensional tin-based perovskite film and being bonded to the flexible silicon wafer;

[0122] A polymethyl methacrylate film is located on the surface of the transparent conductive electrode away from the flexible silicon wafer and corresponding to the two-dimensional tin-based perovskite film;

[0123] Among them, the metal back electrode is copper with a thickness of 150nm;

[0124] The two-dimensional tin-based perovskite film has the chemical formula PEA2SnCl4 and a thickness of 800nm;

[0125] The transparent conductive electrode is aluminum-doped zinc oxide (AZO) with a thickness of 150 nm;

[0126] The thickness of the flexible silicon wafer is 38 μm;

[0127] The thickness of the polymethyl methacrylate film is 8 μm.

[0128] The method for preparing the flexible two-dimensional tin-based perovskite photodetector comprises the following steps:

[0129] S1. Place a silicon wafer with a thickness of 150 to 160 μm in a 1 M NaOH solution at 80° C. for 40 min to obtain a flexible silicon wafer with a thickness of 38 μm.

[0130] S2. Using magnetron sputtering technology, a metal back electrode copper is deposited on the surface of the flexible silicon wafer. The sputtering parameters are controlled as follows: sputtering power 100W, argon pressure 0.2Pa, and time 20min.

[0131] S3. Prepare a two-dimensional tin-based perovskite film on a surface of the flexible silicon wafer away from the metal back electrode, wherein the two-dimensional tin-based perovskite film is located in the middle of the flexible silicon wafer, and two sides of the flexible silicon wafer are not covered by the two-dimensional tin-based perovskite film;

[0132] The chemical formula of the two-dimensional tin-based perovskite film is PEA2SnCl4;

[0133] A two-dimensional tin-based perovskite film is prepared on a surface of a flexible silicon wafer away from a metal back electrode, specifically comprising the following steps:

[0134] Add SnCl2 and PEACl to a solvent and mix to obtain a precursor solution; wherein the molar ratio of SnCl2 to PEACl is 1:2; and the solvent is dimethylformamide;

[0135] The precursor solution was coated on the middle surface of the flexible silicon wafer away from the metal back electrode, reacted at room temperature (25°C), and then annealed to obtain a two-dimensional tin-based perovskite film; the annealing temperature was 100°C and the time was 30 minutes;

[0136] S4. A transparent conductive electrode is prepared on the surface of the two-dimensional tin-based perovskite film, with both sides of the transparent conductive electrode extending toward the area of ​​the flexible silicon wafer not covered by the two-dimensional tin-based perovskite film and being bonded to the flexible silicon wafer;

[0137] Specifically, a transparent conductive electrode is deposited on a two-dimensional tin-based perovskite film by reactive plasma deposition (RPD) technology. The electrode material is aluminum-doped zinc oxide (AZO). The specific preparation process of aluminum-doped zinc oxide (AZO) is to place a block of 99.9% pure aluminum-doped zinc oxide (AZO) with a diameter of 6 mm into a crucible at the center of the RPD, then close the RPD hatch and evacuate to 10 6 Pa; then 100 sccm of argon (Ar) was introduced into the RPD chamber, and a starting current of 30A and a starting voltage of 400V were used to excite the plasma and sputter AZO. The deposition rate was

[0138] S5. Preparing a polymethyl methacrylate film on the surface of the transparent conductive electrode corresponding to the two-dimensional tin-based perovskite film, specifically comprising the following steps:

[0139] Adding polymethyl methacrylate to chlorobenzene to obtain a polymethyl methacrylate solution with a concentration of 0.1 g / mL;

[0140] A polymethyl methacrylate solution was coated on the surface of the transparent conductive electrode corresponding to the two-dimensional tin-based perovskite film, and then annealed at 250°C for 15 minutes to obtain a polymethyl methacrylate film.

[0141] Comparative Example 1

[0142] This comparative example provides a light detector, comprising:

[0143] Flexible silicon wafers;

[0144] A metal back electrode is located on one surface of the flexible silicon wafer;

[0145] A transparent conductive electrode is located on the surface of the flexible silicon wafer away from the metal back electrode;

[0146] Among them, the metal back electrode is copper with a thickness of 150nm;

[0147] The transparent conductive electrode is aluminum-doped zinc oxide (AZO) with a thickness of 150 nm;

[0148] The thickness of the flexible silicon wafer is 38 μm.

[0149] The method for preparing the flexible two-dimensional tin-based perovskite photodetector comprises the following steps:

[0150] S1. Place a silicon wafer with a thickness of 150 to 160 μm in a 1 M NaOH solution at 80° C. for 40 min to obtain a flexible silicon wafer with a thickness of 38 μm.

[0151] S2. Using magnetron sputtering technology, a metal back electrode copper is deposited on the surface of the flexible silicon wafer. The sputtering parameters are controlled as follows: sputtering power 100W, argon pressure 0.2Pa, and time 20min.

[0152] S3, preparing a transparent conductive electrode on the surface of the flexible silicon wafer away from the metal back electrode;

[0153] Specifically, a transparent conductive electrode is deposited on the surface of the flexible silicon wafer away from the metal back electrode by reactive plasma deposition (RPD) technology. The electrode material is aluminum-doped zinc oxide (AZO). The specific preparation process of aluminum-doped zinc oxide (AZO) is to place a block of 99.9% pure aluminum-doped zinc oxide (AZO) with a diameter of 6mm into a crucible at the center of the RPD, then close the RPD hatch and evacuate to 10 6 Pa; then 100 sccm of argon (Ar) was introduced into the RPD chamber, and a starting current of 30A and a starting voltage of 400V were used to excite the plasma and sputter AZO. The deposition rate was

[0154] Performance Testing

[0155] Figure 2 This is the ultraviolet-visible light absorption spectrum of the two-dimensional tin-based perovskite film (PEA2SnCl4) prepared in Example 1; specifically, the two-dimensional tin-based perovskite film (PEA2SnCl4) was deposited on a glass substrate according to the method in Example 1, and the ultraviolet-visible light absorption spectrum was tested.

[0156] pass Figure 2 As can be seen in the figure, the absorption range of this material is the ultraviolet region, starting from 370nm, and the corresponding optical band gap is around 3.3eV.

[0157] Figure 3 The X-ray diffraction (XRD) pattern of the two-dimensional tin-based perovskite film (PEA2SnCl4) prepared in Example 1. Figure 3 It can be found that PEA2SnCl4 has the strongest characteristic peak at 5.3 degrees, showing obvious characteristics of two-dimensional perovskite materials, that is, it has obvious XRD characteristic peaks in the range below 10 degrees. Moreover, its half-peak width is very narrow, less than 0.1 degrees, indicating that its crystallinity is very high and the crystal quality is very high.

[0158] Figure 4 This is the X-ray photoelectron spectroscopy curve of the Sn element in the two-dimensional tin-based perovskite film (PEA2SnCl4) prepared in Example 1. By measuring the composition of the Sn element in the tin-based perovskite material through X-ray photoelectron spectroscopy (XPS), it can be found that due to the good crystallinity of the PEA2SnCl4 perovskite material, the Sn element is almost all in the form of divalent Sn. 2+ This is crucial for improving device performance.

[0159] As a photodetector, the most important evaluation criterion is the ability to convert light signals into electrical properties, that is, the external quantum effect (EQE). This invention compares the use of pure flexible silicon as a light absorbing material and the use of tin-based perovskite materials superimposed on flexible silicon as a light absorbing material. Figure 5 As shown, it is a comparison of the EQE curves of the photodetector prepared in Comparative Example 1 and the flexible two-dimensional tin-based perovskite photodetector prepared in Comparative Example 1. Figure 5 In the figure, the silicon wafer represents comparative example 1, and the silicon wafer + tin-based perovskite device represents embodiment 1.

[0160] from Figure 5It can be seen that the photodetector in Comparative Example 1 has a weak external quantum effect in the ultraviolet region (light with a wavelength of 100-400nm), which means that silicon cannot efficiently convert ultraviolet light into current. However, the flexible two-dimensional tin-based perovskite photodetector in Example 1, through the wide-bandgap tin-based perovskite material, can compensate for the defects of silicon material, thereby enhancing its external quantum effect in the ultraviolet region and improving the device's photodetector capabilities in the ultraviolet region.

[0161] Photoresponsivity is a key parameter to measure the performance of a photodetector, indicating the degree of response of the photodetector to incident light at a specific wavelength. Specifically, photoresponsivity is defined as the ratio of the photocurrent generated by the photodetector to the incident light power, usually expressed in units of A / W (amperes per watt). It reflects the efficiency of the detector in converting the incident light signal into an electrical signal. Figure 6 As shown, it is a comparison of the photoresponsivity curves of the photodetector prepared in Comparative Example 1 and the flexible two-dimensional tin-based perovskite photodetector prepared in Comparative Example 1. Figure 6 In the figure, silicon represents comparative example 1, and silicon + tin-based perovskite device represents embodiment 1.

[0162] from Figure 6 It can be seen that the photodetector in Example 1 successfully improved the responsiveness of the silicon detector in the ultraviolet, i.e., light with a wavelength in the range of 190-380 nm, by depositing a two-dimensional tin-based perovskite (PEA2SnCl4) on a flexible silicon wafer, thereby improving the performance of the device.

[0163] Response time is an important performance parameter of a photodetector, which is defined as the time it takes for a photodetector to generate a response (such as photocurrent) after receiving a light signal. It indicates the speed at which the detector responds to the light signal. Figure 7 As shown, it is the light response curve of the flexible two-dimensional tin-based perovskite photodetector prepared in Example 1 within 0-0.3s; Figure 8 As shown, it is the light response curve of the flexible two-dimensional tin-based perovskite photodetector prepared in Example 1 within the time range of 0-0.02s.

[0164] from Figures 7-8 As can be seen from the graph, the response time of the flexible two-dimensional tin-based perovskite photodetector prepared in Example 1 at 300nm ultraviolet light is: rise time = 300ns, fall time = 300ns. This is a significant improvement compared to conventional perovskite photodetectors (with light response time in the millisecond range).

[0165] The bendable angle has a significant impact on the performance of flexible silicon detectors, because when flexible devices are bent or deformed, the physical and electrical properties of the material will change, which in turn affects its photoelectric detection capabilities. However, since our tin-based perovskite is a two-dimensional material, it is inherently flexible and therefore exhibits excellent bending resistance on flexible silicon wafers. Figure 9 As shown, it is the response of the flexible two-dimensional tin-based perovskite photodetector prepared in Example 1 to 530nm green light after being bent 180 degrees in the forward direction and 180 degrees in the reverse direction.

[0166] from Figure 9 It can be seen that after the flexible two-dimensional tin-based perovskite photodetector prepared in Example 1 is bent 180 degrees in the forward direction and 180 degrees in the reverse direction, the response of the photodetector to 300nm ultraviolet light remains basically unchanged.

[0167] The importance and significance of the number of bends of flexible devices for photodetectors are reflected in their mechanical durability, stability of photoelectric performance, and adaptability to application scenarios. Flexible photodetectors are commonly used in wearable devices, rollable displays, flexible photoelectric sensors and other scenarios. These applications require the device to maintain its performance during repeated bending. Therefore, the number of bends is a key parameter to measure the performance and life of flexible photodetectors. Figure 10 As shown, the flexible two-dimensional tin-based perovskite photodetector prepared in Example 1 was bent 90 degrees in the forward direction and 90 degrees in the reverse direction 10,000 times, and its photoresponse curve under 300nm ultraviolet light was tested.

[0168] from Figure 10 As can be seen in the figure, the flexible two-dimensional tin-based perovskite photodetector prepared in Example 1 was bent 90 degrees forward and 90 degrees backward 10,000 times, and its photoresponsivity was tested under 300nm ultraviolet light. After 10,000 complete bends, the device still maintained 30% of its initial photoresponsivity.

[0169] Due to the special packaging process of the present invention, the tin-based perovskite is packaged by PMMA to isolate the outside air, so that the tin-based perovskite material can work stably in the air. Figure 11 As shown, after the flexible two-dimensional tin-based perovskite photodetector prepared in Example 1 worked in air for 10,000 hours, its photoresponsivity to 300nm ultraviolet light can still maintain 83.6% of the initial level.

[0170] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A flexible two-dimensional tin-based perovskite photodetector, characterized in that: include: Flexible silicon wafers; A metal back electrode is located on one surface of the flexible silicon wafer; a two-dimensional tin-based perovskite film located on a surface of the flexible silicon wafer away from the metal back electrode, the two-dimensional tin-based perovskite film being located in the middle of the flexible silicon wafer, and two sides of the flexible silicon wafer being not covered by the two-dimensional tin-based perovskite film; A transparent conductive electrode is located on the surface of the two-dimensional tin-based perovskite film away from the flexible silicon wafer, with both sides of the transparent conductive electrode extending toward the area of ​​the flexible silicon wafer not covered by the two-dimensional tin-based perovskite film and being bonded to the flexible silicon wafer; The polymethyl methacrylate film is located on a surface of the transparent conductive electrode away from the flexible silicon wafer and corresponding to the two-dimensional tin-based perovskite film.

2. The flexible two-dimensional tin-based perovskite photodetector according to claim 1, wherein: The material of the metal back electrode includes any one of silver, copper and aluminum; And / or, the chemical formula of the two-dimensional tin-based perovskite film is ; Wherein, A is an organic cation, B is a metal cation, and X is a halogen anion; The organic cation includes any one of phenylethylamine cation, butylamine cation, ethylamine cation, isopropylamine cation, propylamine cation, cyclohexylamine cation, benzylamine cation, methoxyethylamine cation, and chloromethylamine cation; The metal cation is or ; The halogen anions include 、 、 Any of; And / or, the transparent conductive electrode comprises any one of indium tin oxide, aluminum-doped zinc oxide, gallium-doped zinc oxide and proton-doped tin oxide; And / or, the thickness of the flexible silicon wafer is 30-50 μm; And / or, the thickness of the metal back electrode is 100-200 nm; And / or, the thickness of the two-dimensional tin-based perovskite film is 500-1000 nm; And / or, the thickness of the transparent conductive electrode is 100-200 nm; And / or, the polymethyl methacrylate film has a thickness of 5 to 10 μm.

3. A method for preparing a flexible two-dimensional tin-based perovskite photodetector according to any one of claims 1 to 2, characterized in that: The following steps are involved: A metal back electrode is prepared on the surface of a flexible silicon wafer; A two-dimensional tin-based perovskite film is prepared on a surface of the flexible silicon wafer away from the metal back electrode, wherein the two-dimensional tin-based perovskite film is located in the middle of the flexible silicon wafer, and two sides of the flexible silicon wafer are not covered by the two-dimensional tin-based perovskite film; A transparent conductive electrode is prepared on the surface of the two-dimensional tin-based perovskite film, with both sides of the transparent conductive electrode extending toward the area of ​​the flexible silicon wafer not covered by the two-dimensional tin-based perovskite film and being bonded to the flexible silicon wafer; A polymethyl methacrylate film is prepared on the surface of the transparent conductive electrode corresponding to the two-dimensional tin-based perovskite film.

4. The method for preparing a flexible two-dimensional tin-based perovskite photodetector according to claim 3, wherein: A silicon wafer with a thickness of 150-160 μm is placed in an alkaline solution and heated to reduce its thickness to 30-50 μm to obtain a flexible silicon wafer.

5. The method for preparing a flexible two-dimensional tin-based perovskite photodetector according to claim 3, wherein: A metal back electrode was prepared on the surface of a flexible silicon wafer by magnetron sputtering. The process parameters controlled during magnetron sputtering were: sputtering power 50-150 W, argon pressure 0.1-0.5 Pa, and time 10-30 min.

6. The method for preparing a flexible two-dimensional tin-based perovskite photodetector according to claim 3, wherein: The chemical formula of the two-dimensional tin-based perovskite film is ; A two-dimensional tin-based perovskite film is prepared on a surface of the flexible silicon wafer away from the metal back electrode, specifically comprising the following steps: Add SnCl2 and PEACl to the solvent and mix to obtain a precursor solution; The precursor solution is coated on the middle portion of the surface of the flexible silicon wafer away from the metal back electrode, and after reaction, annealing is performed to obtain a two-dimensional tin-based perovskite film.

7. The method for preparing a flexible two-dimensional tin-based perovskite photodetector according to claim 3, wherein: A transparent conductive electrode was prepared on the surface of a two-dimensional tin-based perovskite film using reactive plasma deposition, where the deposition rate was .

8. The method for preparing the flexible two-dimensional tin-based perovskite photodetector according to claim 3, wherein: A polymethyl methacrylate film is prepared on the surface of the transparent conductive electrode corresponding to the two-dimensional tin-based perovskite film, specifically comprising the following steps: adding polymethyl methacrylate to chlorobenzene to obtain a polymethyl methacrylate solution having a concentration of 0.1-0.5 g / mL; A polymethyl methacrylate solution is coated on the surface of the transparent conductive electrode corresponding to the two-dimensional tin-based perovskite film, and then annealed at 200-300° C. for 10-20 minutes to obtain a polymethyl methacrylate film.

9. The method for preparing a flexible two-dimensional tin-based perovskite photodetector according to claim 4, wherein: placing a silicon wafer having a thickness of 150 to 160 μm in an alkaline solution, wherein the alkaline solution comprises at least one of a NaOH solution and a KOH solution during a heat treatment step; The molar concentration of the alkali solution is 0.5~5 M; The heating treatment temperature is 70~90℃ and the time is 40~50 min.

10. The method for preparing a flexible two-dimensional tin-based perovskite photodetector according to claim 6, wherein: The precursor solution is coated on the middle portion of the surface of the flexible silicon wafer away from the metal back electrode. After the reaction, in the annealing step, the annealing temperature is 95-105° C. and the time is 25-35 minutes; Will , PEACl is added to the solvent and mixed to obtain a precursor solution, , PEACl has a molar ratio of 1:2; the solvent includes γ-butyrolactone, At least one of methylpyrrolidone, dimethylformamide, dimethyl sulfoxide, deuterated chloroform, 1,3-dimethylpropyleneurea, xylene, n-butanol, dimethylacetamide, propylene glycol ether and cyclohexanone.

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