Flexible two-dimensional tin-based perovskite light detector and preparation method thereof

Abstract

The invention provides a flexible two-dimensional tin-based perovskite light detector and a preparation method thereof. The flexible two-dimensional tin-based perovskite light detector comprises a flexible silicon wafer, a metal back electrode, a two-dimensional tin-based perovskite thin film, a transparent conductive electrode and a polymethyl methacrylate thin film, wherein the polymethyl methacrylate film can effectively block water vapor and oxygen in air and prevent Sn < 2 + > from being oxidized into Sn < 4 + >, so that the environmental stability of the device is improved, and the service life of the device is prolonged; the optical detector provided by the invention is suitable for the fields of wearable equipment, flexible displays and intelligent sensors, has a wide spectrum 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 intelligent and portable electronic devices, flexible optoelectronic devices, as the next generation technology, show great application potential. However, traditional photodetectors are mostly based on rigid silicon materials, which cannot meet the requirements of flexible electronic devices for mechanical flexibility and bendability. At the same time, although lead-based perovskite materials have excellent optoelectronic properties, their toxicity and environmental pollution problems 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, etc., composed of cations and halogen anions) 4 2 - layers are separated by organic molecules, forming an organic-inorganic hybrid layered structure. Two-dimensional perovskite materials such as PEA 2 SnCl 4 As a lead-free and environmentally friendly material, it has a large band gap, excellent light absorption performance and adjustable spectral response, especially in the ultraviolet and blue light bands. In addition, the two-dimensional layered structure of this material enables it to have good mechanical flexibility and environmental stability while maintaining high-efficiency optoelectronic performance, making it suitable for use 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 current two-dimensional perovskite materials used in photodetectors, it is necessary to improve them. Summary of the invention

[0005] In view of this, the present invention provides a flexible photodetector based on flexible silicon wafers and two-dimensional tin-based perovskites and a preparation method thereof, which solves the problems of insufficient mechanical flexibility, poor environmental stability and insufficient spectral response faced by current flexible optoelectronic devices. The photodetector combines the high light absorption efficiency of two-dimensional tin-based perovskite materials with the excellent charge transfer performance of flexible silicon wafers to provide efficient wide-spectrum light detection capabilities, especially in the ultraviolet and visible light ranges, with excellent performance. The invention is particularly suitable for the fields of 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 wafer;

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

[0010] A two-dimensional tin-based perovskite film is located on a 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 two sides of the flexible silicon wafer are 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, and both sides of the transparent conductive electrode extend toward the area of ​​the flexible silicon wafer not covered by the two-dimensional tin-based perovskite film and adhere to the flexible silicon wafer;

[0012] The polymethyl methacrylate film is located on the surface of the transparent conductive electrode away from the flexible silicon sheet 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 A 2 BX 4 ;

[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 100-200 nm;

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

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

[0024] And / or, the thickness of the polymethyl methacrylate film is 5-10 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, wherein both sides of the transparent conductive electrode extend toward the area of ​​the flexible silicon wafer not covered by the two-dimensional tin-based perovskite film and adhere 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 a heating 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 process parameters controlled during magnetron sputtering are: sputtering power 50-150 W, argon gas pressure 0.1-0.5 Pa, and time 10-30 min.

[0032] Preferably, the chemical formula of the two-dimensional tin-based perovskite film is PEA 2 SnCl 4 ;

[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] SnCl 2 , PEACl is added to the solvent and mixed to obtain a precursor solution;

[0035] The precursor solution is coated on the middle 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 with 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 heating 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 of the surface of the flexible silicon sheet away from the metal back electrode, and after the reaction, in the annealing step, the annealing temperature is 95-105° C. and the time is 25-35 min;

[0044] SnCl 2 , PEACl is added to the solvent, mixed, and a precursor solution is obtained, wherein the SnCl 2 , PEACl is 1:2; 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 beneficial effects compared with 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 spectrum 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 ultraviolet and visible light bands, and is suitable for a variety of photoelectric application scenarios. 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 thinned flexible silicon wafer is used, so that the photodetector can work normally under complex mechanical deformation, and is suitable for wearable devices and flexible electronic products; the bendable curvature of the photodetector of the present invention is 3 to 5 cm, and after 10,000 bends, the performance of the photodetector can still maintain 30% of the initial value;

[0049] 4. The flexible two-dimensional tin-based perovskite photodetector of the present invention has excellent environmental stability: through the PMMA packaging process, the photodetector 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;

[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] In order 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 prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0052] Figure 1 It is a schematic structural diagram of the flexible two-dimensional tin-based perovskite photodetector of the present invention;

[0053] Figure 2 The two-dimensional tin-based perovskite film (PEA) prepared in Example 1 2 SnCl 4 )’s UV-visible absorption spectrum;

[0054] Figure 3 The two-dimensional tin-based perovskite film (PEA) prepared in Example 1 2 SnCl 4 )’s X-ray diffraction (XRD) pattern;

[0055] Figure 4 The two-dimensional tin-based perovskite film (PEA) prepared in Example 1 2 SnCl 4 ) is the X-ray photoelectron spectrum curve of Sn element;

[0056] Figure 5 EQE curve comparison 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 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 The photoresponsivity curve of the flexible two-dimensional tin-based perovskite photodetector prepared in Example 1 within 0-0.3s;

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

[0060] Fig. 9 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, and the responsivity of the photodetector to 530nm green light;

[0061] Fig.10 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 for 10,000 times, and its photoresponse curve under 300 nm ultraviolet light was tested;

[0062] Fig.11 The light response curve of the flexible two-dimensional tin-based perovskite photodetector prepared in Example 1 under 300nm ultraviolet light was tested after the detector had worked 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 described embodiments 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 creative work 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 the present 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 only for convenience and brevity and should not be understood as a rigid limitation on the scope of the present 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, it should be considered that the range description from 1 to 6 has 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, which apply regardless of the range. In addition, whenever a numerical range is indicated in this article, it is meant to include any cited numbers (fractions or integers) within the indicated range.

[0065] The present application embodiment provides a flexible two-dimensional tin-based perovskite photodetector, such as Figure 1 As 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 spectrum 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 silicon wafers, 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 flexible photodetectors can be effectively improved. The flexible photodetector based on flexible silicon wafers and two-dimensional tin-based perovskites of the present invention overcomes the problems of environmental unfriendliness, insufficient spectral response, and poor device flexibility in the prior art, and achieves 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 A 2 BX 4 ;

[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 (Phenylethylammonium, PEA + ), referred to as: PEA; Butylammonium cation (BA + ), referred to as: BA; Ethylammonium cation (Ethylammonium, 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 (CMA + ), abbreviated as: CMA.

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

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

[0079] In this structure, the inorganic layer (such as BX 4 2- layer) is covered by an organic layer (A + The inorganic layers interact with each other through weak van der Waals forces, while the organic layers are flexible organic chains, which give 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 100-200 nm;

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

[0084] In some embodiments, the thickness of the transparent conductive electrode 4 is 100-200 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, preparing a metal back electrode on the side of the flexible silicon wafer;

[0088] S2. 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;

[0089] S3, preparing a transparent conductive electrode 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 with a thickness of 150 to 160 μm is placed in an alkaline solution, heated, and chemically etched to reduce its thickness to 30 to 50 μm to obtain a flexible silicon wafer. This step ensures the thickness uniformity and mechanical stability of the silicon wafer by precisely controlling the heating temperature and etching time.

[0092] In some embodiments, magnetron sputtering technology is used to deposit a metal back electrode on the surface of a flexible silicon wafer; the material of the metal back electrode can be silver, copper or aluminum, and the specific selection can be adjusted according to the device application scenario and conductive requirements. By adjusting the sputtering parameters, such as: sputtering power of 50 to 150 W, argon gas 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 PEA 2 SnCl 4 ;

[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] SnCl 2 、PEACl(chemical formula C 6 H 5 CH 2 CH 2 NH 3 Cl (PEACl, phenethylammonium chloride) is added to the solvent and mixed 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, in the central area of ​​the flexible silicon wafer away from the metal back electrode surface, a confined growth technique is used to prepare a two-dimensional tin-based perovskite (PEA) 2 SnCl 4 ) film; this step is to prepare a precursor solution (such as SnCl 2 The perovskite film with good crystal structure is formed by uniformly coating the designated area of ​​the flexible silicon wafer with PEACl and annealing at low temperature. The confined growth can precisely control the thickness and grain size of the film, ensuring the improvement of the optoelectronic performance.

[0098] In some embodiments, 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

[0099] In some embodiments, a transparent conductive electrode is deposited on a two-dimensional tin-based perovskite film by reactive plasma deposition (RPD) technology, and 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 the efficient charge collection performance of the device while ensuring the incident efficiency of light; the specific preparation process of aluminum-doped zinc oxide (AZO) is to put 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, sputtering AZO, and 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 with 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 on 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 and prevent 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 heating, 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 of the surface of the flexible silicon wafer away from the metal back electrode, and after the reaction, in the annealing step, the annealing temperature is 95 to 105° C. and the time is 25 to 35 minutes;

[0108] SnCl 2 , PEACl is added to the solvent, mixed, and a precursor solution is obtained, wherein the SnCl 2 , PEACl is 1:2; 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 preparing the two-dimensional tin-based perovskite film on the surface of the flexible silicon wafer, the flexible silicon wafer is cut into long strips using laser cutting or a diamond tool, and the size can be controlled to be 6 cm×1 cm (i.e., 6 cm in length and 1 cm in width). The cutting process requires precise control of the moving trajectory and speed of the cutting tool to ensure that the edge of the flexible silicon wafer is neat and crack-free.

[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 the present invention has high photoelectric conversion efficiency in both ultraviolet and visible light bands, and is suitable for a variety of photoelectric application scenarios. 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;

[0112] 2. Excellent flexibility: The thinned flexible silicon wafer is used to enable the photodetector to work normally under complex mechanical deformation, and is suitable for wearable devices and flexible electronic products. The photodetector of the present invention has a bendable curvature of 3 to 5 cm. After 10,000 bends, the performance of the photodetector can still maintain 30% of the initial performance.

[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 following further describes the flexible two-dimensional tin-based perovskite photodetector and its preparation method of the present application with specific examples. This section further describes the content of the present invention in conjunction with specific examples, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the embodiments 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 wafer;

[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 two-dimensional tin-based perovskite film away from the flexible silicon wafer, and both sides of the transparent conductive electrode extend toward the area of ​​the flexible silicon wafer not covered by the two-dimensional tin-based perovskite film and adhere 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 chemical formula of the two-dimensional tin-based perovskite film is PEA 2 SnCl 4 , thickness is 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 above-mentioned flexible two-dimensional tin-based perovskite photodetector comprises the following steps:

[0129] S1, placing a silicon wafer with a thickness of 150-160 μm in a 1M NaOH solution at 80° C. for 40 min to make the thickness of the silicon wafer 38 μm, thereby obtaining a flexible silicon wafer;

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

[0131] S3, preparing 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 both 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 PEA 2 SnCl 4 ;

[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] SnCl 2 , PEACl are added to the solvent and mixed to obtain a precursor solution; wherein SnCl 2 The molar ratio of , PEACl is 1:2; 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, and both sides of the transparent conductive electrode extend toward the area of ​​the flexible silicon wafer not covered by the two-dimensional tin-based perovskite film and adhere 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, and the electrode material is aluminum-doped zinc oxide (AZO); the specific preparation process of aluminum-doped zinc oxide (AZO) is to put 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, and 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 30 A and a starting voltage of 400 V were used to excite the plasma to sputter AZO at a deposition rate of

[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] 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 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 wafer;

[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 above-mentioned flexible two-dimensional tin-based perovskite photodetector comprises the following steps:

[0150] S1, placing a silicon wafer with a thickness of 150-160 μm in a 1M NaOH solution at 80° C. for 40 min to make the thickness of the silicon wafer 38 μm, thereby obtaining a flexible silicon wafer;

[0151] S2. Using magnetron sputtering technology, the metal back electrode copper is deposited on the surface of the flexible silicon wafer; the sputtering parameters are adjusted as follows: sputtering power 100W, argon gas pressure 0.2Pa, 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, and the electrode material is aluminum-doped zinc oxide (AZO); the specific preparation process of aluminum-doped zinc oxide (AZO) is to put a block of 99.9% pure aluminum-doped zinc oxide (AZO) with a diameter of 6mm into a crucible in the center of RPD, and 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 to sputter AZO at a deposition rate of

[0154] Performance Testing

[0155] Figure 2 The two-dimensional tin-based perovskite film (PEA) prepared in Example 1 2 SnCl 4 ) UV-visible absorption spectrum; Specifically, a two-dimensional tin-based perovskite film (PEA) was deposited on a glass substrate according to the method in Example 1. 2 SnCl 4 ) to test the absorption spectrum of ultraviolet and visible light.

[0156] pass Figure 2 It can be seen that 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 two-dimensional tin-based perovskite film (PEA) prepared in Example 1 2 SnCl 4 ) of the X-ray diffraction (XRD) pattern. Figure 3 PEA can be found in 2 SnCl 4The strongest characteristic peak is at 5.3 degrees, which shows the obvious characteristics of two-dimensional perovskite materials, that is, it has obvious XRD characteristic peaks in the range below 10 degrees. And its half-peak width is very narrow, less than 0.1 degrees, which means that its crystallinity is very high and the crystal quality is very high.

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

[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). The present 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, such as 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 example 1.

[0160] from Figure 5 It can be seen that the external quantum effect of the photodetector in comparative example 1 in the ultraviolet part (light with a wavelength of 100-400nm) is weak, that is, silicon cannot efficiently convert ultraviolet light into current. The flexible two-dimensional tin-based perovskite photodetector in Example 1 can make up for the defects of silicon materials through the wide-bandgap tin-based perovskite material, thereby enhancing its external quantum effect in the ultraviolet part and improving the photodetector capability of the device in the ultraviolet part.

[0161] Photoresponsivity is a key parameter to measure the performance of a photodetector, which indicates the degree of response of a 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 incident light signals into electrical signals. 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 example 1.

[0162] from Figure 6 As can be seen in the figure, the photodetector in Example 1 is formed by depositing a two-dimensional tin-based perovskite (PEA) on a flexible silicon wafer. 2 SnCl 4 ) successfully achieved the goal of improving the responsiveness of silicon detectors in the ultraviolet, that is, light with a wavelength in the range of 190-380nm, 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 photoresponsivity 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 It can be seen that 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. Compared with the general perovskite photodetector (light response time is at the ms level), it has a significant improvement.

[0165] The bending 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 a flexible material itself, so it shows excellent bending resistance on flexible silicon wafers. Fig. 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 Fig. 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 is reflected in their mechanical durability, the stability of photoelectric performance, and the adaptability of application scenarios. Flexible photodetectors are usually used in wearable devices, rollable displays, flexible photoelectric sensors and other scenarios. These applications require the device to maintain its performance during repeated bends. Therefore, the number of bends is a key parameter to measure the performance and life of flexible photodetectors. Fig.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 Fig.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 photoresponse curve under 300nm ultraviolet light was tested. After 10,000 complete times, the device can still maintain 30% of the initial photoresponse of the device.

[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. Fig.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 protection scope of the present invention.

Claims

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

2. The flexible two-dimensional tin-based perovskite photodetector according to claim 1, characterized in that: 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 A2BX4 Wherein, A is an organic cation, B is a metal cation, and X is a halogen anion; 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; The metal cation is Sn 2+ or Pb 2+ ; The halogen anions include Cl - Br - ,I - 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 sheet is 30 to 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 thickness of the polymethyl methacrylate film is 5-10 μm.

3. A method for preparing a flexible two-dimensional tin-based perovskite photodetector as claimed in any one of claims 1 to 2, characterized in that: The following steps are involved: A metal back electrode is prepared on the side of the 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, wherein both sides of the transparent conductive electrode extend toward the area of ​​the flexible silicon wafer not covered by the two-dimensional tin-based perovskite film and adhere 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 the flexible two-dimensional tin-based perovskite photodetector according to claim 3, characterized in that: A silicon wafer with a thickness of 150 to 160 μm is placed in an alkaline solution and subjected to heating treatment to reduce its thickness to 30 to 50 μm, thereby obtaining a flexible silicon wafer.

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

6. The method for preparing a flexible two-dimensional tin-based perovskite photodetector according to claim 3, characterized in that: The chemical formula of the two-dimensional tin-based perovskite film is PEA2SnCl4; 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 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 the flexible two-dimensional tin-based perovskite photodetector according to claim 3, characterized in that: A transparent conductive electrode was prepared on the surface of a two-dimensional tin-based perovskite film by 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, characterized in that: 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 with a concentration of 0.1-0.5 g / mL; 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.

9. The method for preparing the flexible two-dimensional tin-based perovskite photodetector according to claim 3, characterized in that: Placing a silicon wafer having a thickness of 150 to 160 μm in an alkaline solution, wherein the alkaline solution includes at least one of a NaOH solution and a KOH solution during the heating treatment step; The molar concentration of the alkali solution is 0.5 to 5 M; The heating treatment temperature is 70-90°C and the time is 40-50 minutes.

10. The method for preparing a flexible two-dimensional tin-based perovskite photodetector according to claim 6, characterized in that: The precursor solution is coated on the middle of the surface of the flexible silicon wafer away from the metal back electrode, and after the reaction, in the annealing step, the annealing temperature is 95-105° C. and the time is 25-35 minutes; 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.

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