Perovskite photoelectric detector and preparation method thereof

Abstract

The invention belongs to the technical field of photoelectric detectors, and relates to a perovskite photoelectric detector and a preparation method thereof. The method specifically comprises the following steps: spin-coating a self-assembled monomolecular material on a substrate, and depositing to form a self-assembled monomolecular layer after annealing; spin-coating a perovskite precursor solution on the surface of the self-assembled monomolecular layer, annealing to form a perovskite layer, and arranging metal electrodes at two ends of the top of the perovskite layer to obtain the perovskite photoelectric detector, the service life of photo-induced electrons of the perovskite layer is prolonged, and the crystallization quality of the perovskite layer is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of photoelectric detectors and relates to a perovskite photoelectric detector and a preparation method thereof. Background Art

[0002] Perovskite is a general term for ABX3-type compounds with a structure similar to CaTiO3. With the deepening of scientific research, scientists have discovered a large number of perovskite materials with different elemental compositions. Lead halide perovskite is a general term for a typical class of perovskite compounds. Due to its many excellent properties, lead halide perovskite has attracted widespread attention in the optoelectronic science research in the 21st century. In the past decade, three-dimensional lead halide perovskites have shined in the field of solar cells, demonstrating the excellent properties of lead halide perovskite materials. The exciton binding energy in three-dimensional lead halide perovskites is small, usually tens of millielectron volts, so the electrons and holes in three-dimensional lead halide perovskites can be regarded as free. The free electrons and holes generated by light excitation are easier to separate. When an external circuit exists, the charges move in a directional manner to form a current, realizing the process of converting light signals into electrical signals. Therefore, three-dimensional lead halide perovskites are also good photoelectric detection materials.

[0003] At present, perovskite photodetectors are optoelectronic devices with broad application prospects. Their structures mainly include several key components, such as substrate, electron transport layer, perovskite layer, hole transport layer and top electrode. However, the lifetime of photogenerated electrons in the perovskite layer is generally not high, which has become one of the key factors restricting its performance improvement. The short lifetime of photogenerated electrons means that electrons are easily lost due to various factors (such as defects, impurities, etc.) during the transmission process, resulting in a decrease in the response speed and sensitivity of the photodetector. In addition, the crystallization quality of the perovskite layer is also an important factor affecting the performance of the photodetector. At present, the crystallization quality of the perovskite layer is generally poor, with a large number of lattice defects and dislocations. These defects will not only reduce the lifetime of photogenerated electrons, but also affect the transmission efficiency of electrons and holes, resulting in a decrease in the detection efficiency and stability of the photodetector. At the same time, differences in crystallization quality may also cause fluctuations in the performance of the device in different regions, further limiting its reliability in practical applications. Summary of the invention

[0004] The purpose of the present invention is to solve the technical problems in the prior art that the photogenerated electron lifetime of the perovskite layer is not high and the crystallization quality of the perovskite layer is not high, and to provide a perovskite photodetector and a preparation method thereof.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a method for preparing a perovskite photodetector, which specifically comprises the following steps: S1: Spin coating the self-assembled monolayer material on the substrate, and then depositing it to form a self-assembled monolayer after annealing; S2: Spin-coating a perovskite precursor solution on the surface of the self-assembled monolayer and annealing to form a perovskite layer, and setting metal electrodes at both ends of the top of the perovskite layer to obtain the perovskite photodetector.

[0006] Preferably, the self-assembled monomolecular material is MeO-2PACz.

[0007] Preferably, the preparation method of the perovskite precursor solution is: mixing methylamino iodide, potassium ammonium bromide, cesium iodide, lead bromide, lead iodide and methylammonium chloride, then adding a mixed solution of DMF and DMSO, and stirring to obtain a yellow clear perovskite precursor solution.

[0008] Preferably, the volume ratio of DMF to DMSO is 4:1.

[0009] Preferably, the spin coating condition in S1 is spin coating at 2000-5000 rpm for 20-40 s.

[0010] Preferably, the spin coating conditions in S2 are: spin coating at 1500-2000 rpm for 10 s, and then spin coating at 5000 rpm for 40-50 s; and chlorobenzene is added dropwise 40 s after the start of spin coating.

[0011] Preferably, the annealing condition in S1 is annealing at 100° C. for 5-15 min; and the annealing condition in S2 is annealing at 100° C. for 25-35 min.

[0012] In a second aspect, the present invention provides a perovskite photodetector, which comprises, from bottom to top, a substrate, a self-assembled monolayer and a perovskite layer; metal electrodes are arranged at both ends of the top of the perovskite layer.

[0013] Preferably, the substrate is a silicon wafer or glass; wherein a SiO2 layer is provided on the surface of the silicon wafer.

[0014] Preferably, the material of the metal electrode is gold, silver or copper.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention deposits a self-assembled monomolecular material on the interface of the buried perovskite to form a self-assembled monomolecular layer as a charge transfer layer, which can effectively extract the photogenerated holes in the perovskite layer, thereby extending the life of the photogenerated electrons in the perovskite, so that more photogenerated electrons can reach the electrode to generate current before recombination. Compared with a photodetector that does not use a self-assembled monomolecular layer material, the phosphate group on the top of the self-assembled monomolecular layer of the present invention can anchor the perovskite layer, thereby improving the crystallization quality of the perovskite layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0017] Figure 1 This is a schematic structural diagram of a perovskite photodetector according to the present invention; Figure 2 This is an absorption spectrum of the perovskite layer in the perovskite photodetector prepared in Example 1; Figure 3 This is the light response curve of the perovskite photodetector without self-assembled molecular layer; Figure 4 This is a light response curve diagram of the perovskite photodetector prepared in Example 1; Wherein: 1-substrate; 2-self-assembled monolayer; 3-perovskite layer; 4-metal electrode. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0019] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. 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.

[0020] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0021] In the description of the embodiments of the present invention, it should be noted that if the terms "upper", "lower", "horizontal", "inner", etc. indicate an orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed when in use, it is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0022] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", which does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0023] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] The present invention is further described in detail below in conjunction with the accompanying drawings: The first object of the present invention is to provide a method for preparing a perovskite photodetector, which specifically comprises the following steps: S1: Spin coating a self-assembled monomolecular material on a substrate 1, and depositing it after annealing to form a self-assembled monomolecular layer 2; wherein the spin coating condition is spin coating at 2000-5000 rpm for 20-40 seconds.

[0025] S2: Spin coating the perovskite precursor solution on the surface of the self-assembled monolayer 2 (FA 0.95 MA 0.05 ) 0.95 Cs 0.05 Pb(I 0.95 Br 0.05 )3) and annealing to form a perovskite layer 3, and setting metal electrodes 4 at both ends of the top of the perovskite layer 3 to obtain the perovskite photodetector. The spin coating conditions are: spin coating at 1500-2000 rpm for 10 seconds, and then spin coating at 5000 rpm for 40-50 seconds; chlorobenzene is added dropwise as an anti-solvent 40 seconds after the start of spin coating.

[0026] The spin coating conditions described in S1 are spin coating at 2000-5000 rpm for 20-40 seconds, which ensures the uniform distribution of the self-assembled monolayer material on the substrate 1, helps to spread the material quickly, and reduces the formation of agglomerations and voids, thereby forming a compact and uniform self-assembled monolayer 2.

[0027] The spin coating conditions described in S2 are: spin coating at 1500-2000 rpm for 10 seconds, and then spin coating at 5000 rpm for 40-50 seconds; chlorobenzene is added dropwise 40 seconds after the start of spin coating. The addition of chlorobenzene can quickly reduce the concentration of the solution, induce rapid nucleation and growth of perovskite crystals, thereby reducing the formation of grain boundaries and defects. At the same time, chlorobenzene also helps to adjust the volatilization rate of the solvent, further optimizing the structure and properties of the perovskite crystals.

[0028] The annealing condition in S1 is annealing at 100°C for 5-15 minutes. This step helps the self-assembled monomolecular material to form a stable and ordered monolayer on the substrate. During the annealing process, the interaction between molecules is strengthened, making the monolayer more compact and uniform. At the same time, annealing can also remove residual solvents and impurities during the spin coating process, improving the purity and stability of the monolayer.

[0029] The annealing condition in S2 is annealing at 100°C for 25-35 minutes. This step helps the solute in the perovskite precursor solution to further crystallize and improve. During the annealing process, the solvent gradually evaporates and the solute concentration increases, thereby promoting the nucleation and growth of the crystal. At the same time, annealing can also reduce defects and impurities in the crystal and improve the quality and purity of the crystal.

[0030] The self-assembled monomolecular material is 2-(3,6-dimethoxy-9H-carbazole-9-yl)ethyl)phosphonic acid (MeO-2PACz). As a self-assembled monomolecular material, MeO-2PACz can accurately regulate the interface energy level between the substrate 1 and the perovskite layer 3. The carbazole group and the phosphonic acid group in the MeO-2PACz molecule have specific electron and hole transport properties, respectively, which help to optimize the charge distribution and transmission path at the interface, thereby reducing the charge recombination rate at the interface and improving the photoelectric conversion efficiency of the photodetector. In addition, the tight structure formed by self-assembly between MeO-2PACz molecules effectively prevents the penetration of environmental factors such as water and oxygen, and improves the long-term stability and durability of the photodetector.

[0031] The preparation method of the perovskite precursor solution is: methyl iodide, potassium bromide, cesium iodide, lead bromide, lead iodide and methyl ammonium chloride are mixed, and then a mixed solution of N, N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) is added, and a yellow clear perovskite precursor solution is obtained after stirring. Among them, the volume ratio of DMF and DMSO is 4:1, which helps to regulate the growth process of perovskite crystals. DMF and DMSO have different solubility and volatility. Through their synergistic effect, an environment conducive to the uniform growth of perovskite crystals can be formed, reducing the formation of grain boundaries and defects, thereby improving the quality of the perovskite layer 3.

[0032] Exemplarily, the concentration of the spin-coated perovskite precursor solution is 1.5 mol / L.

[0033] The second object of the present invention is a perovskite photodetector which comprises, from bottom to top, a substrate 1, a self-assembled monolayer 2 and a perovskite layer 3; metal electrodes 4 are arranged at both ends of the top of the perovskite layer 3.

[0034] The self-assembled monolayer 2 of the present invention optimizes the interface between the substrate and the perovskite layer, provides a uniform, dense and defect-free interface, helps to reduce charge recombination and energy loss at the interface, thereby improving the photoelectric conversion efficiency and performance of the photodetector. The perovskite layer 3 is conducive to the transmission and collection of carriers, thereby improving the response speed and sensitivity of the photodetector. Metal electrodes 4 are arranged at both ends of the top of the perovskite layer 3 to form a complete perovskite photodetector structure. The metal electrode 4 can provide good conductivity and good contact with the perovskite layer, thereby reducing contact resistance and energy loss, and improving the photoelectric conversion efficiency and stability of the photodetector.

[0035] Wherein, the substrate 1 is a silicon wafer or glass; the surface of the silicon wafer is provided with a 280nm thick SiO2 layer. As a covering layer on the surface of the silicon wafer, the SiO2 layer has excellent optical properties. It can effectively reduce the reflection of the silicon wafer surface and improve the transmittance of light, thereby increasing the light absorption efficiency of the perovskite layer 3.

[0036] The thickness of the self-assembled monolayer 2 is 1-5 nm, which not only ensures good contact with the substrate 1 and the perovskite layer 3, but also avoids the charge transfer barrier that may be caused by an overly thick interface layer.

[0037] The thickness of the perovskite layer 3 is 200-600nm, which helps to balance the carrier transmission and recombination process. A perovskite layer 3 that is too thin will cause the carrier transmission path to be too short, increasing the recombination probability; while a perovskite layer 3 that is too thick will increase the transmission resistance and reduce the carrier mobility. Within this thickness range, the perovskite layer 3 provides a sufficient transmission path while maintaining a low recombination rate, thereby optimizing the performance of the photodetector.

[0038] The material of the metal electrode 4 is gold, silver or copper. Gold, silver and copper are all metals with excellent electrical conductivity. As metal electrodes 4, they can ensure efficient transmission of charges in the photodetector. In particular, in the photoelectric conversion process, the metal electrode 4 can quickly collect and transmit the photogenerated charges generated by the perovskite layer 3, thereby improving the response speed and sensitivity of the photodetector. At the same time, the thickness of the metal electrode 4 is 50-100 nm, which not only ensures the electrical conductivity of the electrode, but also avoids light absorption loss and charge transmission barriers caused by excessive thickness.

[0039] Example 1 Weigh 232.8 mg of methyl iodide (FAI), 7.98 mg of potassium ammonium bromide (MABr), 19.49 mg of cesium iodide (CsI), 27.53 mg of lead bromide (PbBr2), 676.6 mg of lead iodide (PbI2) and 30.38 mg of methylamine chloride (MACl), add a mixed solvent of 1 mL of DMF and 0.25 mL of DMSO to the reagent bottle containing the above drugs, add a magnetic stirrer to the reagent bottle for 2 hours to obtain a yellow clear perovskite precursor solution (concentration of 1.5 moL / L) for use.

[0040] On a silicon wafer with a 280nm SiO2 layer on the surface, a self-assembled monomolecular material MeO-2PACz is spin-coated (spin-coated at 4000 rpm for 30 seconds), and after annealing (annealing at 100°C for 10 minutes), a self-assembled monolayer 2 is deposited; on the surface of the self-assembled monolayer 2, a perovskite precursor solution is spin-coated (spin-coated at 2000 rpm for 10 seconds, and then spin-coated at 5000 rpm for 40 seconds; 200 μL of chlorobenzene is added dropwise 40 seconds after the start of spin coating) and annealed (annealed at 100°C for 30 minutes) to form a perovskite layer 3 (with a thickness of about 400nm), and gold electrodes are set at both ends of the top of the perovskite layer 3 to obtain the perovskite photodetector.

[0041] Example 2 Weigh 232.8 mg of methyl iodide (FAI), 7.98 mg of potassium ammonium bromide (MABr), 19.49 mg of cesium iodide (CsI), 27.53 mg of lead bromide (PbBr2), 676.6 mg of lead iodide (PbI2) and 30.38 mg of methylamine chloride (MACl), add a mixed solvent of 1 mL of DMF and 0.25 mL of DMSO to the reagent bottle containing the above drugs, add a magnetic stirrer to the reagent bottle for 2 hours to obtain a yellow clear perovskite precursor solution (concentration of 1.5 moL / L) for use.

[0042] On glass, self-assembled monolayer material MeO-2PACz is spin-coated (spin-coated at 2000 rpm for 40 seconds), and then deposited to form self-assembled monolayer 2 after annealing (annealing at 100°C for 5 minutes); perovskite precursor solution is spin-coated on the surface of self-assembled monolayer 2 (spin-coated at 2000 rpm for 10 seconds, and then spin-coated at 5000 rpm for 40 seconds; 200 μL of chlorobenzene is added dropwise 40 seconds after the start of spin coating) and annealed (annealed at 100°C for 25 minutes) to form perovskite layer 3, and gold electrodes are set at both ends of the top of perovskite layer 3 to obtain the perovskite photodetector.

[0043] Example 3 Weigh 232.8 mg of methyl iodide (FAI), 7.98 mg of potassium ammonium bromide (MABr), 19.49 mg of cesium iodide (CsI), 27.53 mg of lead bromide (PbBr2), 676.6 mg of lead iodide (PbI2) and 30.38 mg of methylamine chloride (MACl), add a mixed solvent of 1 mL of DMF and 0.25 mL of DMSO to the reagent bottle containing the above drugs, add a magnetic stirrer to the reagent bottle for 2 hours to obtain a yellow clear perovskite precursor solution (concentration of 1.5 moL / L) for use.

[0044] On glass, self-assembled monolayer material MeO-2PACz is spin-coated (spin-coated at 3000 rpm for 35 seconds), and after annealing (annealing at 100°C for 8 minutes), a self-assembled monolayer 2 is deposited; on the surface of the self-assembled monolayer 2, a perovskite precursor solution is spin-coated (spin-coated at 2000 rpm for 10 seconds, and then spin-coated at 5000 rpm for 45 seconds; 200 μL of chlorobenzene is added dropwise 40 seconds after the start of spin coating) and annealed (annealed at 100°C for 25 minutes) to form a perovskite layer 3, and gold electrodes are set at both ends of the top of the perovskite layer 3 to obtain the perovskite photodetector.

[0045] Example 4 Weigh 232.8 mg of methyl iodide (FAI), 7.98 mg of potassium ammonium bromide (MABr), 19.49 mg of cesium iodide (CsI), 27.53 mg of lead bromide (PbBr2), 676.6 mg of lead iodide (PbI2) and 30.38 mg of methylamine chloride (MACl), add a mixed solvent of 1 mL of DMF and 0.25 mL of DMSO to the reagent bottle containing the above drugs, add a magnetic stirrer to the reagent bottle for 2 hours to obtain a yellow clear perovskite precursor solution (concentration of 1.5 moL / L) for use.

[0046] On a silicon wafer with a SiO2 layer on the surface, a self-assembled monolayer material MeO-2PACz is spin-coated (spin-coated at 4500 rpm for 25 seconds), and after annealing (annealing at 100°C for 12 minutes), a self-assembled monolayer 2 is deposited; on the surface of the self-assembled monolayer 2, a perovskite precursor solution is spin-coated (spin-coated at 2000 rpm for 10 seconds, and then spin-coated at 5000 rpm for 40 seconds; 200 μL of chlorobenzene is added dropwise 40 seconds after the start of spin coating) and annealed (annealed at 100°C for 35 minutes) to form a perovskite layer 3, and silver electrodes are set at both ends of the top of the perovskite layer 3 to obtain the perovskite photodetector.

[0047] Example 5 Weigh 232.8 mg of methyl iodide (FAI), 7.98 mg of potassium ammonium bromide (MABr), 19.49 mg of cesium iodide (CsI), 27.53 mg of lead bromide (PbBr2), 676.6 mg of lead iodide (PbI2) and 30.38 mg of methylamine chloride (MACl), add a mixed solvent of 1 mL of DMF and 0.25 mL of DMSO to the reagent bottle containing the above drugs, add a magnetic stirrer to the reagent bottle for 2 hours to obtain a yellow clear perovskite precursor solution (concentration of 1.5 moL / L) for use.

[0048] On a silicon wafer with a SiO2 layer on the surface, a self-assembled monolayer material MeO-2PACz is spin-coated (spin-coated at 5000 rpm for 20 seconds), and after annealing (annealing at 100°C for 15 minutes), a self-assembled monolayer 2 is deposited; on the surface of the self-assembled monolayer 2, a perovskite precursor solution is spin-coated (spin-coated at 2000 rpm for 10 seconds, and then spin-coated at 5000 rpm for 50 seconds; 200 μL of chlorobenzene is added dropwise 40 seconds after the start of spin coating) and annealed (annealed at 100°C for 35 minutes) to form a perovskite layer 3, and copper electrodes are set at both ends of the top of the perovskite layer 3 to obtain the perovskite photodetector.

[0049] Example 6 Weigh 232.8 mg of methyl iodide (FAI), 7.98 mg of potassium ammonium bromide (MABr), 19.49 mg of cesium iodide (CsI), 27.53 mg of lead bromide (PbBr2), 676.6 mg of lead iodide (PbI2) and 30.38 mg of methyl ammonium chloride (MACl), add a mixed solvent of 4 mL of DMF and 1 mL of DMSO to the reagent bottle containing the above drugs, add a magnetic stirrer to the reagent bottle for 2 hours to obtain a yellow clear perovskite precursor solution for use.

[0050] On a silicon wafer with a SiO2 layer on the surface, a self-assembled monolayer material MeO-2PACz is spin-coated (spin-coated at 5000 rpm for 20 seconds), and after annealing (annealing at 100°C for 15 minutes), a self-assembled monolayer 2 is deposited; on the surface of the self-assembled monolayer 2, a perovskite precursor solution is spin-coated (spin-coated at 2000 rpm for 10 seconds, and then spin-coated at 5000 rpm for 50 seconds; 200 μL of chlorobenzene is added dropwise 40 seconds after the start of spin coating) and annealed (annealed at 100°C for 35 minutes) to form a perovskite layer 3, and copper electrodes are set at both ends of the top of the perovskite layer 3 to obtain the perovskite photodetector.

[0051] like Figure 2 As shown, the perovskite layer 3 has a strong absorption capability in the visible light range, and the wide spectral response range enables the perovskite photodetector to detect more spectral regions, thereby increasing the application range of the detector.

[0052] like Figure 3 and Figure 4 As shown, from the test results of the photoresponsivity of the photodetector, it can be seen that at the extreme point of 760nm, the photoresponsivity of the photodetector prepared in Example 1 is 60 times that of the photodetector without a self-assembled molecular layer (6.93621: 0.11484); at 600nm, the photoresponsivity of the photodetector prepared in Example 1 is 60 times that of the photodetector without a self-assembled molecular layer (11.2975: 0.18749). In the embodiment, due to the introduction of self-assembled molecules, the crystallization quality of perovskite is improved (the phosphate groups of the self-assembled molecules anchor the perovskite to make the perovskite layer crystallization more orderly and dense), and the self-assembled molecules can extract the photogenerated holes in the perovskite, so that the carrier lifetime is extended, and the photoresponsivity of the photodetector is greatly improved by nearly two orders of magnitude.

[0053] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a perovskite photodetector, characterized in that: The specific steps include: S1: spin coating a self-assembled monolayer material on a substrate (1), and depositing the self-assembled monolayer (2) after annealing; S2: Spin-coating a perovskite precursor solution on the surface of the self-assembled monolayer (2) and annealing to form a perovskite layer (3), and arranging metal electrodes (4) at both ends of the top of the perovskite layer (3) to obtain the perovskite photodetector.

2. The method for preparing a perovskite photodetector according to claim 1, characterized in that: The self-assembled monomolecular material is MeO-2PACz.

3. The method for preparing a perovskite photodetector according to claim 1, characterized in that: The preparation method of the perovskite precursor solution is: methylammonium iodide, potassium ammonium bromide, cesium iodide, lead bromide, lead iodide and methylammonium chloride are mixed, and then a mixed solution of DMF and DMSO is added, and a yellow clear perovskite precursor solution is obtained after stirring.

4. The method for preparing a perovskite photodetector according to claim 3, characterized in that: The volume ratio of DMF to DMSO is 4:

1.

5. The method for preparing a perovskite photodetector according to claim 1, characterized in that: The spin coating conditions described in S1 are spin coating at 2000-5000 rpm for 20-40 s.

6. The method for preparing a perovskite photodetector according to claim 1, characterized in that: The spin coating conditions in S2 are: spin coating at 1500-2000 rpm for 10 s, and then spin coating at 5000 rpm for 40-50 s; chlorobenzene is added dropwise 40 s after the start of spin coating.

7. The method for preparing a perovskite photodetector according to claim 1, characterized in that: The annealing condition of S1 is annealing at 100° C. for 5-15 min; the annealing condition of S2 is annealing at 100° C. for 25-35 min.

8. A perovskite photodetector, characterized in that: From bottom to top, it comprises a substrate (1), a self-assembled monolayer (2) and a perovskite layer (3); both ends of the top of the perovskite layer (3) are provided with metal electrodes (4).

9. The perovskite photodetector according to claim 8, characterized in that: The substrate (1) is a silicon wafer or glass; wherein a SiO2 layer is provided on the surface of the silicon wafer.

10. The perovskite photodetector according to claim 8, characterized in that: The material of the metal electrode (4) is gold, silver or copper.

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