Two-dimensional hybrid perovskite nanosheets with out-of-plane ferroelectricity and preparation method and application thereof

Abstract

The application discloses a two-dimensional hybrid perovskite nanosheet with out-of-plane ferroelectricity and a preparation method and application thereof. The preparation process of the nanosheet is as follows: raw materials including lead iodide, phenethylammonium iodide and methylammonium hydroiodide are dispersed in an organic solvent to obtain a mother liquor; a red precipitate is generated by adding a precipitating solution dropwise into the mother liquor, and supernatant is taken and placed on a lower PDMS substrate; an upper PDMS substrate is covered on the lower PDMS substrate on which the supernatant is placed, and after heat treatment and volatilization of the organic solvent, the upper and lower PDMS substrates are separated. The nanosheet has out-of-plane ferroelectric polarization and single ferroelectric domain characteristics based on organic-inorganic hybridization and a special space group structure, and has advantages of excellent structural stability and conductivity. A two-dimensional photodetector prepared by using the nanosheet can be spontaneously polarized, thereby being self-powered, and the on-off ratio of the photodetector is as high as 10 4 , and a photocurrent can reach 30 nA, thereby greatly improving the comprehensive performance of the photodetector.

Description

TECHNICAL FIELD

[0001] The application relates to an organic-inorganic two-dimensional hybrid perovskite nanosheet, in particular to a two-dimensional hybrid perovskite nanosheet with out-of-plane ferroelectricity and a preparation method and application thereof, and belongs to the technical field of perovskite materials. BACKGROUND

[0002] The polarization direction of a ferroelectric material can be reversed under the action of an external electric field, and is an important carrier for realizing a nonvolatile photodetector and has been a focus of research. Oxide perovskites are a kind of classic ferroelectric materials and have a large ferroelectric polarization value, for example, the polarization value of SrTiO3 is 100 , and the polarization value of BiAlO3 is 90 . However, most of these materials have a wide band gap, a small absorption coefficient and weak luminescence. In addition, when the size of the material is less than a few hundred nanometers, the depolarization field has a greater effect, resulting in weakened ferroelectricity. These characteristics affect their practical applications. Therefore, people have begun to shift their focus to organic-inorganic hybrid perovskites. Researchers first explored the ferroelectricity of 3D hybrid perovskites, such as MAPbI3, but the ferroelectricity thereof is controversial due to phase separation and ion migration. In 2D organic-inorganic hybrid perovskites, the presence of long organic chains can inhibit ion migration and phase separation, which can better compensate for this shortcoming. In addition, the synthesis of 2D hybrid perovskites is mostly carried out by a solution method, and various polar organic chains and atoms can be used to synthesize 2D organic-inorganic hybrid perovskites, resulting in the breaking of structural symmetry and causing ferroelectricity. Therefore, 2D organic-inorganic hybrid perovskites are excellent ferroelectric materials.

[0003] In recent years, it has been found that a variety of 2D organic-inorganic hybrid perovskites have ferroelectricity. For example, (n-BA)2PbCl4, (BPA)2PbBr4, (IA)2(MA)2Pb3Br 10 , and the like, these materials all have a large ferroelectric polarization value and a high Curie temperature. In addition, 2D organic-inorganic hybrid perovskites have a direct band gap, a large absorption coefficient and the like. These make 2D organic-inorganic hybrid perovskites have good application prospects in photodetectors, X-ray detectors, linear polarization and circular polarization detectors and the like. According to the prior art, 2D Dion-Jacobson (DJ) phase perovskites have out-of-plane ferroelectricity due to structural characteristics. The ferroelectric polarization direction of 2D Ruddlesden-Popper (RP) perovskites is mostly in-plane. Out-of-plane polarization is more convenient for the preparation and practical application of a detector, and finding a new type of 2D RP perovskite with out-of-plane polarization can deepen people's understanding of this field.

[0004] The morphology of the reported 2D hybrid perovskite is basically a film and a bulk phase, and the thickness is more than several hundred nanometers. These morphologies have many internal defects, complex structure and uneven thickness. Of course, people can reduce the thickness of the material to tens of nanometers or even nanometers by mechanical exfoliation, but the 2D perovskite exfoliated by mechanical exfoliation is easily eroded by water and oxygen in the air, resulting in structural decomposition. The 2D perovskite nanosheet directly synthesized is relatively stable in the air, but its transfer difficulty coefficient is higher, which is not conducive to the preparation of subsequent detectors and application. In addition, the organic long chain in the 2D organic-inorganic hybrid perovskite leads to poor contact between the material and the electrode, large resistance and small current. How to use the 2D organic-inorganic hybrid perovskite nanosheet to prepare a high-performance detector is a difficulty and challenge in the field of 2D hybrid perovskite. SUMMARY

[0005] In view of the problems existing in the prior art, a first object of the present application is to provide a two-dimensional RP hybrid perovskite nanosheet with out-of-plane ferroelectricity. The nanosheet is based on organic-inorganic hybridization and a special space group structure, which gives it out-of-plane ferroelectric polarization and single ferroelectric domain characteristics. The nanosheet has uniform thickness and excellent structural stability and conductivity, effectively solving the technical problem that the thickness and structural stability of the perovskite nanosheet cannot be considered simultaneously in the prior art.

[0006] A second object of the present application is to provide a preparation method of a two-dimensional hybrid perovskite nanosheet with out-of-plane ferroelectricity. The method is based on the synergistic effect of anti-solvent method and spatial confinement, and directly synthesizes two-dimensional perovskite nanosheets on a PDMS substrate. After sorting by thickness, the two-dimensional perovskite nanosheets can be transferred by dry method for detector preparation, effectively solving the technical problem of high transfer difficulty of the synthesized two-dimensional perovskite nanosheets in the prior art.

[0007] A third object of the present application is to provide an application of a two-dimensional hybrid perovskite nanosheet with out-of-plane ferroelectricity, which is used for preparing a two-dimensional out-of-plane ferroelectric photodetector. Based on the excellent performance of the above-mentioned perovskite nanosheet, the two-dimensional photodetector prepared by using the nanosheet has out-of-plane ferroelectricity of the perovskite nanosheet, which can be spontaneously polarized, thereby forming a self-powered light response detector. The on-off ratio of the detector is as high as 10 4 , and the photocurrent can reach 30nA, which greatly improves the comprehensive performance of the detector.

[0008] In order to achieve the above technical purposes, the present application provides a preparation method of a two-dimensional hybrid perovskite nanosheet with out-of-plane ferroelectricity, comprising the following steps: step S1, uniformly dispersing raw materials including lead iodide, phenethylammonium iodide and formamidinium hydroiodide in an organic solvent to obtain a mother liquor;

[0009] Step S2, adding a precipitation solution to the mother liquor to generate a red precipitate, and then placing the supernatant on a lower PDMS substrate after standing.

[0010] Step S3, the upper PDMS substrate is covered on the lower PDMS substrate on which the supernatant is placed, and heat treatment is carried out, after the organic solvent is completely volatilized, the upper and lower PDMS substrates are separated, and the product is obtained.

[0011] The mass ratio of the lead iodide, the phenethylammonium iodide and the formamidine hydriodate is 1:1.5-2.5:0.8-1.5.

[0012] The steps S1-S3 are carried out in an oxygen-free environment.

[0013] In the preparation method, the mass ratio of the raw material components is strictly according to the above requirements, if the mass ratio of the lead iodide, the phenethylammonium iodide and the formamidine hydriodate does not meet the above requirements, on the one hand, the perovskite nanosheet with regular morphology cannot be formed, on the other hand, the product cannot guarantee to be a single crystal structure.

[0014] As a preferred scheme, the concentration of the mother liquor is 8-30 mmol / L.

[0015] As a preferred scheme, the organic solvent is at least one of acetonitrile, methanol, tetrahydrofuran and dimethyl sulfoxide.

[0016] As a preferred scheme, the precipitation liquid is at least one of benzene, toluene and xylene.

[0017] As a preferred scheme, the area of the upper PDMS substrate is greater than that of the lower PDMS substrate.

[0018] As a preferred scheme, the heat treatment process is that the upper PDMS substrate is heated at 50-60 DEG C for 5-15 min.

[0019] The application further provides a two-dimensional hybrid perovskite nanosheet with out-of-plane ferroelectricity, which is obtained by the method according to any one of the above, and the space group is P1. The P1 space group proves that the nanosheet has a polar structure, which is a prerequisite for generating ferroelectricity.

[0020] The application further provides an application of the two-dimensional hybrid perovskite nanosheet with out-of-plane ferroelectricity, which is used for preparing a two-dimensional out-of-plane ferroelectric photoelectric detector, and the preparation process is as follows:

[0021] (1) graphene is mechanically exfoliated, and a bottom graphene is transferred to a photoelectric detector substrate, and an interface coupling solution is coated, to obtain an optimized graphene-substrate interface;

[0022] Slowly peel the perovskite nanosheet from the PDMS substrate, sort according to thickness, transfer to the bottom graphene by dry method, and transfer the top graphene, connect the bottom and top graphene to the source electrode and drain electrode respectively, and the device is obtained.

[0023] As a preferred scheme, the preparation process of the photoelectric detector substrate is as follows: after spin coating the Si substrate attached with SiO2 with negative glue, drying, exposure, etching and development, the substrate precursor is obtained; vacuum evaporation of Ni electrode and Au electrode on the substrate precursor, and removal of excess Ni and Au, and the device is obtained.

[0024] As a preferred scheme, the negative glue is NR9-3000PY.

[0025] As a preferred scheme, the thickness of the Ni electrode is 8-15 nm, and the thickness of the Au electrode is 40-60 nm.

[0026] As a preferred scheme, the coated reagent material is Spiro-OMeTAD and / or PC61BM.

[0027] As a preferred scheme, the interface coupling solution needs to be coated again before transferring the top graphene.

[0028] As a preferred scheme, after the reagent is coated, a mixed cleaning agent is used to wash away the excess reagent on the substrate; the mixed cleaning agent is chlorobenzene and chloroform in a volume ratio of 1:0.5-1.5. Further preferably, the mixed cleaning agent is chlorobenzene and chloroform in a volume ratio of 1:1.

[0029] Compared with the prior art, the technical scheme provided by the present application has the following beneficial technical effects:

[0030] (1) The two-dimensional hybrid perovskite nanosheet provided by the present application is based on organic-inorganic hybridization and a special space group structure, which endows it with out-of-plane ferroelectric polarization and single ferroelectric domain characteristics. The nanosheet has uniform thickness and excellent structural stability and conductivity, effectively solving the technical problem that the thickness and structural stability of perovskite nanosheets cannot be simultaneously considered in the prior art.

[0031] (2) The preparation method provided by the present application is based on the synergistic effect of anti-solvent method and spatial confinement, and directly synthesizes two-dimensional perovskite nanosheets on a PDMS substrate. After sorting according to thickness, the nanosheets can be transferred by dry method for detector preparation, effectively solving the technical problem of high transfer difficulty of two-dimensional perovskite nanosheets synthesized in the prior art.

[0032] (3) Based on the excellent performance of the perovskite nanosheet, the two-dimensional photoelectric detector prepared by using the nanosheet has a high on-off ratio of 10 4 , and a photocurrent of 30 nA, and the comprehensive performance of the detector is greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 Optical photos of the nanosheets with different thicknesses provided in Example 1 of the present application;

[0034] Among them, Figure 1 (a) the thickness of the nanosheet is 17 nm, Figure 1 (b) the thickness of the nanosheet is 30.7 nm, Figure 1 (c) the thickness of the nanosheet is 39.4 nm, Figure 1 (d) the thickness of the nanosheet is 46.2 nm, Figure 1 (e) the thickness of the nanosheet is 59 nm, Figure 1 (f) the thickness of the nanosheet is 72.6 nm, Figure 1 (g) the thickness of the nanosheet is 109 nm, Figure 1 (h) the thickness of the nanosheet is 728 nm;

[0035] Figure 2 AFM test results of the nanosheets with different thicknesses obtained in Example 1 of the present application and the corresponding height maps thereof;

[0036] Among them, Figure 2 (a) the thickness of the nanosheet is 17 nm, Figure 2 (b) the thickness of the nanosheet is 30.7 nm, Figure 2 (c) the thickness of the nanosheet is 39.4 nm, Figure 2 (d) the thickness of the nanosheet is 46.2 nm, Figure 2 (e) the thickness of the nanosheet is 59 nm, Figure 2 (f) the thickness of the nanosheet is 72.6 nm, Figure 2 (g) the thickness of the nanosheet is 109 nm, Figure 2 (h) the thickness of the nanosheet is 728 nm;

[0037] Figure 3 SEM scanning diagram of the perovskite nanosheet;

[0038] Among them, Figure 3 (a) is an optical photo of the nanosheet, Figure 3 (b) is an SEM image, Figure 3 (c)-(f) are EDS diagrams of I, N, C, and Pb, respectively;

[0039] Figure 4 X-ray diffraction pattern of the nanosheet with a thickness of 800 nm provided in Example 1 of the present application;

[0040] Figure 5 Phase diagram of the initial state of the nanosheet with a thickness of 30 nm in Example 2 of the present application;

[0041] Figure 6 Piezoelectric force scanning diagram of the nanosheet with a thickness of 30 nm in Example 2 of the present application;

[0042] wherein, Figure 6 (a) is a phase diagram, Figure 6 (b) is a phase difference diagram of the region to which different bias voltages are applied;

[0043] Figure 7 Preparation process of the detector provided in Example 3 of the present application and the corresponding optical photograph;

[0044] wherein, Figure 7 (a) corresponds to the process of transferring the bottom graphene, Figure 7 (b) corresponds to the process of spin-coating Sprio-OMeTAD / PC61BM, Figure 7 (c) corresponds to the process of transferring the perovskite, Figure 7 (d) corresponds to the process of spin-coating Sprio-OMeTAD / PC61BM on the surface of the perovskite, Figure 7 (e) corresponds to the process of transferring the upper graphene, Figure 7 (f) corresponds to the process of cleaning Sprio-OMeTAD / PC61BM on the substrate;

[0045] Figure 8 I-V curve of the detector treated by the coating reagent provided in Example 3 of the present application;

[0046] Figure 8 (a) I-V curve of the detector with the coating reagent of Sprio-OMeTAD / PC61BM, Figure 8 (b) I-V curve of the detector with the coating reagent of Sprio-OMeTAD / Sprio-OMeTAD, Figure 8 (c) I-V curve of the detector with the coating reagent of blank / PC61BM;

[0047] Figure 9 Performance characterization diagram of the detector obtained in Example 3;

[0048] Figure 9 (a) is a plot of the change of photocurrent with time under the action of 0 bias voltage, with 520 nm pulsed light as the light source, Figure 9(b) optical response time graph for 520 nm pulsed light source;

[0049] Figure 10 I-V curve of the detector provided by Example 4 of the present application for different nanosheet thicknesses;

[0050] Figure 10 (a) I-V curve of the detector for a nanosheet thickness of 40 nm, Figure 10 (b) I-V curve of the detector for a nanosheet thickness of 60 nm; Figure 10 (c) I-V curve of the detector for a nanosheet thickness of 80 nm;

[0051] Figure 11 optical photograph of the detector provided by Comparative Example 1 of the present application;

[0052] Figure 12 I-V curve of the detector obtained from Example 3 and Comparative Example 1 of the present application;

[0053] Figure 12 (a) I-V curve of the detector for Comparative Example 1 of the present application; Figure 12 (b) I-V curve of the detector for Example 3. DETAILED DESCRIPTION

[0054] The present application will be further explained in connection with specific embodiments, including more detailed embodiments and operational details. The purpose of providing the embodiments is not to limit the scope of the present application, but on the contrary, the embodiments are developed in accordance with the technical solutions of the present application, and are only illustrative, as a detailed description to better understand the content of the present application.

[0055] Those of ordinary skill in the art can make various modifications and improvements under the guidance of the disclosure of the present application, and these modifications and improvements should all belong to the protection of the present application without departing from the general concept and purpose of the present application.

[0056] Example 1

[0057] The present embodiment provides a two-dimensional hybrid perovskite nanosheet with out-of-plane ferroelectricity, and the specific preparation process is as follows:

[0058] (1) Cut the PDMS with model PF-30x30-0065-X4 into 0.5x0.5 cm squares, and attach them to one end of a clean glass slide;

[0059] (2) Dissolve 0.0145 g of PbI2, 0.0156 g of PEAI and 0.0033 g of FAI in 2.5 ml of acetonitrile, and stir at 50-55°C for 2 hours to obtain a mother liquor; after 2 hours, take 300 Pour the mother liquor into a 5ml empty bottle, add about 3 drops of toluene, a red precipitate appears, let stand, and then take 20 ml of the solution. The supernatant was then dropped onto the prepared lower PDMS substrate;

[0060] (3) The upper PDMS substrate was placed on the lower PDMS substrate containing the supernatant, and then heat-treated at 53°C for 10 min. After the organic solvent was completely evaporated, the upper and lower PDMS substrates were separated to obtain PEA2FAPb2I7 nanosheets.

[0061] After the obtained nanosheets were sorted by thickness, their optical photographs are as follows: Figure 1 As shown, the thicknesses from left to right are 17nm, 30.7nm, 39.4nm, 46.2nm, 69nm, 72.6nm, 109nm, and 782nm. It can be seen that as the nanosheets increase in thickness, their color on the silicon wafer changes.

[0062] Furthermore, the present invention also conducted AFM and SEM tests on nanosheets of different thicknesses, and the results are as follows: Figure 2 and Figure 3 As shown. (Through) Figure 3 As can be seen, the nanosheets provided in this embodiment have uniform thickness, smooth surface, and uniform element distribution. XRD characterization also shows that their space group is P1.

[0063] Example 2

[0064] The 40 nm thick nanosheets from Example 1 were transferred onto a 1 cm × 1 cm conductive substrate, which was a Si / SiO2 substrate with 10 nm of Ni and 40-60 nm of Au deposited on it.

[0065] The above nanosheets were subjected to PFM scanning without bias, and the results are as follows: Figure 5 As shown in the figure, the PFM without applied bias reveals the intrinsic polarization state of the nanosheet, indicating that the entire nanosheet consists of a single ferroelectric domain. Further, when a bias voltage is applied... The results of the PFM scan after vertical bias are as follows: Figure 6 As shown, the phase of the perovskite nanosheets exhibits a 180° flip when different bias voltages are applied, and the phase difference also proves that the perovskite nanosheets have out-of-plane ferroelectricity.

[0066] Example 3

[0067] This embodiment uses perovskite nanosheets with a thickness of 40 nm from Example 1 to fabricate a two-dimensional photodetector. The process is as follows:

[0068] (1) Cut the Si / SiO2 substrate into 1 cm x 1 cm substrate pieces, drop the negative glue of NR9-3000PY on the cut Si / SiO2 substrate, spin at a speed of 3500 rpm for 30 s, and then heat at 110°C for 60 s. Next, expose the substrate to light for 7.5 s using a photoetching machine, heat the exposed substrate at 100°C for 60 s, then immerse it in a developing solution of RD6 type for 12 s, rinse it with deionized water, and dry it with nitrogen. Form the source and drain electrodes by sequentially evaporating 10 nm of Ni and 40-60 nm of Au in a vacuum environment at 2 x 10 -4 Pa, remove the nickel and gold outside the pattern by bubbling acetone, and then immerse it in n-hexane for 2 s and dry it with nitrogen to obtain a photodetector substrate. Then, mechanically exfoliate the graphene and transfer the bottom layer of graphene to the photodetector substrate, and coat the interface coupling solution at 20 mg / ml at 1800 rpm for 20 s to obtain an optimized graphene / substrate interface.

[0069] (2) Transfer the selected perovskite nanosheet to the graphene coated with the reagent, wash away the excess reagent on the substrate with a mixture of chlorobenzene and chloroform at a ratio of 1:1, coat the interface coupling solution at 20 mg / ml again at 1800 rpm for 20 s, and transfer the top layer of graphene. The bottom and top layers of graphene are connected to the source and drain electrodes, respectively, to obtain a two-dimensional photodetector.

[0070] The reagents coated on the bottom and top layers of graphene are Spiro-OMeTAD / PC61BM, Spiro-OMeTAD / Spiro-OMeTAD, and blank / PC61BM, respectively. Then, perform photoelectric current tests on the above two-dimensional photodetectors, and the results are shown in Figure 8 As can be seen from the figure, any one of the above interface coupling solutions can optimize the interface of the two-dimensional photodetector, reduce the resistance, and increase the current of the photodetector. The maximum short-circuit current of the two-dimensional photodetector can reach 30 nA. Further, perform related performance tests on the above photodetectors, and the results are shown in Figure 9 As can be seen from the figure, use a 520 nm laser as the light source, the laser power is 60 mw / cm 2 , no bias is applied, the photocurrent is 2.5 nA, and the on-off ratio is 10 4 . This is due to the out-of-plane ferroelectricity of the perovskite nanosheet, which has spontaneous polarization and can form a self-powered light response detector. After 10 3 cycles, the photocurrent of the device remains essentially unchanged, indicating that this structure has good stability. The light response time is 328 / 483 , which is relatively fast.

[0071] Example 4

[0072] This example is identical to the photodetector of Example 3, except that the interfacial coupling solution coated between the bottom graphene and the top graphene is blank / PC61BM, and the thickness of the nanosheet is different, from thin to thick, 40 nm, 60 nm, and 80 nm.

[0073] The short-circuit current of the photodetector obtained by using the nanosheet with different thicknesses is tested, and the results are shown in Figure 10 It can be seen from Figure 10 that the short-circuit current gradually decreases from 25 nA to 20 pA as the thickness of the nanosheet increases.

[0074] Comparative Example 1

[0075] This comparative example is identical to Example 3, except that no interfacial coupling solution is coated. The optical photograph of the photodetector obtained in this comparative example is shown in Figure 11

[0076] The photodetector obtained in this comparative example is tested for photoelectric current, and compared with the two-dimensional photodetector of Example 3, in which the reagent coated is Spiro-OMeTAD / Spiro-OMeTAD, and the results are shown in Figure 12 It can be seen from Figure 12 that the short-circuit current of the photodetector obtained in this comparative example is only about 3 pA, which is much lower than 30 nA in Example 3.​

Claims

1. A method for preparing two-dimensional hybrid perovskite nanosheets with out-of-plane ferroelectricity, characterized in that, The application relates to a method for preparing a two-dimensional out-of-plane ferroelectric photodetector. The method comprises the following steps: S1, uniformly dispersing raw materials including lead iodide, phenethylammonium iodide and formamidine hydroiodide in an organic solvent to obtain a mother liquor; S2, adding a precipitation solution to the mother liquor to generate a red precipitate, and then placing the supernatant on a lower PDMS substrate; S3, covering an upper PDMS substrate on the lower PDMS substrate with the supernatant, and performing heat treatment until the organic solvent is completely volatilized, and then separating the upper and lower PDMS substrates to obtain the two-dimensional out-of-plane ferroelectric photodetector. The mass ratio of the lead iodide, the phenethylammonium iodide and the formamidine hydroiodide is 1:1.5-2.5:0.8-1.

5. The steps S1-S3 are all carried out in an oxygen-free environment. The concentration of the mother liquor is 8-30 mmol / L, and the organic solvent is at least one of acetonitrile, methanol, tetrahydrofuran and dimethyl sulfoxide. The precipitation solution is at least one of benzene, toluene and xylene, and the area of the upper PDMS substrate is larger than that of the lower PDMS substrate.

2. The method for preparing a two-dimensional hybrid perovskite nanosheet with out-of-plane ferroelectricity according to claim 1, characterized in that: The heat treatment process is heating at 50-60 DEG C for 5-15 min.

3. The method of claim 1, wherein: The two-dimensional out-of-plane ferroelectric photodetector prepared by the method has a space group P1.

4. The method of claim 1, wherein: The application further relates to a preparation process of a two-dimensional out-of-plane ferroelectric photodetector.

5. A two-dimensional hybrid perovskite nanosheet with out-of-plane ferroelectricity, characterized in that: (1) mechanically peeling off graphene and transferring the bottom graphene to a photodetector substrate, and coating an interface coupling solution to obtain an optimized graphene-substrate interface; (2) slowly peeling off perovskite nanosheets from a PDMS substrate, sorting the perovskite nanosheets according to thickness, transferring the perovskite nanosheets to the bottom graphene by a dry method, transferring top graphene, and connecting the bottom graphene and the top graphene to a source electrode and a drain electrode respectively.

6. Use of a two-dimensional hybrid perovskite nanosheet with out-of-plane ferroelectricity according to claim 5, characterized in that: The preparation process of the photodetector substrate comprises the following steps: spin-coating a Si substrate with SiO2 attached with a negative glue, drying, exposing, etching and developing to obtain a substrate precursor; vacuum evaporating Ni electrodes and Au electrodes on the substrate precursor, and removing the excess Ni and Au to obtain the photodetector substrate. The negative glue is NR9-3000PY, the thickness of the Ni electrodes is 8-15 nm, and the thickness of the Au electrodes is 40-60 nm. The interface coupling solution is Spiro-OMeTAD and / or PC61BM, and the top graphene needs to be coated with the interface coupling solution again before being transferred.

7. Use of a two-dimensional hybrid perovskite nanosheet with out-of-plane ferroelectricity according to claim 6, characterized in that: After the interface coupling solution is coated, a mixed cleaning agent is used to wash away the excess reagent on the substrate; the mixed cleaning agent is chlorobenzene and chloroform in a volume ratio of 1:0.5-1.

5.

8. Use of a two-dimensional hybrid perovskite nanosheet with out-of-plane ferroelectricity according to claim 7, characterized in that: ​ 9. Use of a two-dimensional hybrid perovskite nanosheet with out-of-plane ferroelectricity according to claim 8, characterized in that: ​ 10. Use of a two-dimensional hybrid perovskite nanosheet with out-of-plane ferroelectricity according to claim 8, characterized in that: ​

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