Two-dimensional organic-inorganic hybrid perovskite and molybdenum diselenide heterojunction photoelectric detector and preparation method thereof

Abstract

The invention discloses a two-dimensional organic-inorganic hybrid perovskite and molybdenum diselenide heterojunction photoelectric detector and a preparation method thereof. The photoelectric detector comprises a substrate; the electrode layer is positioned on one side of the substrate; the photoelectric conversion part is arranged on the side, away from the substrate, of the electrode layer, and materials of the photoelectric conversion part comprise two-dimensional organic and inorganic hybrid perovskite (C6H13NH3) 2PbI4 (C6PI), molybdenum diselenide (MoSe2) and a protective layer hexagonal boron nitride (h-BN). According to the invention, by constructing the heterostructure, the advantages of high absorption coefficient and extremely low dark current of the two-dimensional perovskite material and the advantages of high carrier mobility and wide light response range of the two-dimensional transition metal disulfide are combined, so that the performance of the photoelectric detector is improved to a great extent; the method has good performance in the aspects of light response rate, response time, response range and the like.

Description

Technical Field

[0001] The present application relates to the field of photoelectric detection technology, and in particular to a two-dimensional organic-inorganic hybrid perovskite and molybdenum diselenide heterojunction photoelectric detector and a preparation method thereof. Background Art

[0002] The discovery of graphene in 2004 triggered a wave of exploration of two-dimensional materials. Subsequently, more and more two-dimensional bandgap materials were discovered, such as transition metal dichalcogenides (TMDCs), black phosphorus (BP), two-dimensional perovskites, etc. TMDCs have rich tunable band gaps and high carrier mobility. Two-dimensional perovskites have the advantages of high absorption coefficient, low exciton binding energy, and long carrier diffusion length. However, due to the low carrier mobility and lack of effective optical gain mechanism, the optical response rate of photodetectors based on single perovskites is low, which cannot meet people's needs for photodetectors. TMDCs with atomic thickness have the advantages of high carrier mobility, high photoresponse, and rich and adjustable bandgap width. However, due to the thickness of the atomic layer, the absorption of light and the performance of optoelectronic devices are limited.

[0003] Therefore, how to improve the performance of photodetectors is a problem that needs to be solved urgently. Summary of the invention

[0004] The main purpose of the present application is to provide a two-dimensional organic-inorganic hybrid perovskite and molybdenum diselenide heterojunction photoelectric detector and a preparation method thereof, aiming to solve the technical problem of how to improve the performance of the photoelectric detector.

[0005] To achieve the above objectives, the present application provides a two-dimensional organic-inorganic hybrid perovskite (C6H 13 A photoelectric detector of a heterojunction of NH3)2PbI4(C6PI) and molybdenum diselenide (MoSe2), characterized in that the photoelectric detector comprises:

[0006] substrate;

[0007] An electrode layer, located on one side of the substrate;

[0008] A photoelectric conversion unit is provided on a side of the electrode layer away from the substrate, wherein the material of the photoelectric conversion unit includes two-dimensional organic-inorganic hybrid perovskite C6PI and molybdenum diselenide;

[0009] The protective layer, made of hexagonal boron nitride, is located on the upper surface of C6PI and molybdenum diselenide to prevent the perovskite from oxidation and moisture absorption.

[0010] Furthermore, the photodetector further comprises a dielectric layer and an adhesive layer, wherein:

[0011] The dielectric layer is disposed between the substrate and the bonding layer; the material of the dielectric layer includes at least one of SiO2, Al2O3 and HfO2;

[0012] The bonding layer is arranged between the electrode layer and the dielectric layer; the material of the bonding layer includes at least one of Ti, Cr and Pd.

[0013] Further, the material of the substrate includes at least one of Si, SiC and SOI; and / or the material of the electrode layer includes at least one of Au, Ag, Pd and Pt.

[0014] In addition, to achieve the above-mentioned purpose, the present application also provides a method for preparing a photoelectric detector, comprising the following steps:

[0015] providing a substrate;

[0016] An electrode layer is prepared on the substrate by electron beam evaporation technology;

[0017] C6PI, molybdenum diselenide, and hexagonal boron nitride are sequentially transferred to the electrode layer to form a photoelectric conversion part and a protective layer to obtain a photodetector.

[0018] Specifically, C6PI, MoSe and HBN were sequentially transferred to the empty electrode by dry transfer.

[0019] Furthermore, the method of forming the photoelectric conversion unit and the protective layer includes:

[0020] C6PI, molybdenum diselenide and hexagonal boron nitride materials were obtained by mechanical exfoliation.

[0021] The resulting material was transferred onto a polydimethylsiloxane pad, and the material of target thickness was selected;

[0022] The obtained materials are transferred to the empty electrodes in sequence by dry transfer method.

[0023] The synthesis process of C6PI crystal includes: C6H 13 The crystal synthesis of NH3I reactant and the synthesis of C6PI crystals; this method is also applicable to the synthesis of other two-dimensional organic and inorganic perovskite materials in the same system, such as (C8H 17 NH3)2PbI4(C8PI);

[0024] C6H 13The synthesis process of NH3I crystals includes: adding 10 mL of ethanol and 2.32 mL of hexylamine into a beaker to form a mixture, which is then stored in an ice bath at 0°C; adding HI dropwise into the mixture and stirring for 2 hours to obtain a solvent; heating the solvent at 50°C using a rotary evaporator until white ammonium salt powder appears and the solvent residue is completely evaporated; washing the ammonium salt powder with ether; and drying the washed ammonium salt powder in a vacuum oven at 60°C for 24 hours to obtain C6H 13 NH3I crystals.

[0025] Furthermore, the synthesis process of C6PI crystals includes: 80 mg C6H 13 NH3I and 80.5 mg of lead iodide were dissolved in 2 mL of N,N-dimethylformamide (DMF), and dichloromethane was used as an antisolvent to assist the crystallization of C6PI. The formed crystals were washed with toluene and then dried to obtain C6PI crystals.

[0026] Furthermore, the provided substrate is first cleaned with isopropanol, then cleaned with deionized water for a second time, and blown dry with nitrogen; and the nitrogen-dried substrate is subjected to plasma treatment.

[0027] Furthermore, the plasma treatment time is 15 to 30 minutes; and / or the plasma treatment temperature is 20 to 40°C.

[0028] The photodetector of the two-dimensional organic-inorganic hybrid perovskite and molybdenum diselenide heterojunction of the present application is one of the effective means to meet the demand for high-performance photodetectors, and exploring new photoelectric materials and structures is one of the effective means; the two-dimensional perovskite material has a high absorption coefficient and extremely low dark current, while the two-dimensional transition metal disulfide has a high carrier mobility and a wide response band. Combining the advantages of these two materials, the advantage of the two-dimensional material surface having no dangling bonds and being easy to stack with other two-dimensional materials to form a heterojunction is utilized. By constructing a heterostructure, the two-dimensional perovskite material has a high absorption coefficient and extremely low dark current, and the two-dimensional transition metal disulfide has high carrier mobility, a wide light response range and other advantages, which greatly improves the performance of the photodetector, and has good performance in terms of light response rate, response time and response range. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0031] Figure 1 A schematic diagram of the three-dimensional molecular structure of C6PI and molybdenum diselenide in the C6PI and molybdenum diselenide heterojunction photodetector of Example 1 of the present invention;

[0032] Figure 2 Schematic diagram of the planar structure of a C6PI and molybdenum diselenide heterojunction photodetector according to Example 1 of the present invention;

[0033] Figure 3 An optical microscope image of the photoelectric conversion portion of the photodetector of the C6PI and molybdenum diselenide heterojunction of Example 1 of the present invention;

[0034] Figure 4 This is an atomic force microscope image of a photodetector of a C6PI and molybdenum diselenide heterojunction according to Example 1 of the present invention;

[0035] Figure 5 This is a PL spectrum diagram of C6PI and the heterojunction at 473nm in the photodetector of the C6PI and molybdenum diselenide heterojunction of Example 1 of the present invention;

[0036] Figure 6 This is a Raman characteristic spectrum diagram of molybdenum diselenide in the photoelectric detector of the C6PI and molybdenum diselenide heterojunction of Example 1 of the present invention;

[0037] Figure 7 The I of the C6PI and MoSe heterojunction photodetector of Example 1 of the present invention under 450nm-700nm light irradiation ds -V ds Graphs;

[0038] Figure 8 The relationship between the responsivity and wavelength of the photoelectric detector of the C6PI and molybdenum diselenide heterojunction of Example 1 of the present invention;

[0039] Fig. 9 This is a photocurrent scanning image of the photodetector of the C6PI and molybdenum diselenide heterojunction of Example 1 of the present invention;

[0040] Fig.10 It is a time-resolved photocurrent response diagram of the C6PI and molybdenum diselenide heterojunction photodetector of Example 1 of the present invention under different bias conditions;

[0041] Fig.11Schematic diagram of the planar structure of a C8PI and indium selenide (InSe) heterojunction photodetector according to Example 2 of the present invention;

[0042] Fig.12 An optical microscope image of the photoelectric conversion portion of the photodetector of the C8PI and indium selenide heterojunction of Example 2 of the present invention;

[0043] Fig.13 The I of the photodetector of the C8PI and indium selenide heterojunction of Example 2 of the present invention under light irradiation ds -V ds Graph.

[0044] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0045] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0046] In order to better understand the technical solution of the present application, a detailed description will be given below in conjunction with the accompanying drawings and specific implementation methods.

[0047] The main solution of the present application is: the photodetector includes: a substrate; an electrode layer, located on one side of the substrate; a photoelectric conversion part, arranged on the side of the electrode layer away from the substrate, the material of the photoelectric conversion part includes two-dimensional organic-inorganic hybrid perovskite C6PI and molybdenum diselenide; a protective layer, the material includes hexagonal boron nitride, located on the upper surface of C6PI and molybdenum diselenide, and is used to prevent the perovskite from oxidation and moisture absorption.

[0048] At present, the discovery of graphene in 2004 has triggered a wave of exploration of two-dimensional materials. Subsequently, more and more two-dimensional band gap materials have been discovered, such as transition metal dichalcogenides (TMDCs), black phosphorus (BP), two-dimensional perovskites, etc. TMDCs have rich tunable band gaps and high carrier mobility. Two-dimensional perovskites have the advantages of high absorption coefficient, low exciton binding energy, and long carrier diffusion length. However, due to the low carrier mobility and lack of effective optical gain mechanism, the optical response rate of photodetectors based on single perovskites is low, which cannot meet people's needs for photodetectors. TMDCs with atomic thickness have the advantages of high carrier mobility, high photoresponse, and rich and adjustable band gap width. However, due to the thickness of the atomic layer, the absorption of light and the performance of optoelectronic devices are limited. Therefore, how to improve the performance of photodetectors is a problem that needs to be solved urgently.

[0049] Since there are no dangling bonds on the surface of two-dimensional materials and they have atomic-level flatness, there is no need to consider lattice matching when constructing vdW heterostructures with two or more materials, which provides great convenience for constructing vdW heterostructures. Two-dimensional TMDCs have the characteristics of rich tunable band gaps and high electron mobility, and perovskites have advantages such as large light absorption coefficients. By selecting materials with suitable band structures for matching and constructing vdW heterojunctions, high-performance photodetectors can be obtained.

[0050] In order to meet people's demand for high-performance photodetectors, exploring new photoelectric materials and new structures is an effective means. Two-dimensional perovskite materials have high absorption coefficients and extremely low dark currents. Two-dimensional transition metal sulfides have high carrier mobility and a wide response band.

[0051] The photodetector of the two-dimensional organic-inorganic hybrid perovskite and molybdenum diselenide heterojunction of the present application is one of the effective means to meet the demand for high-performance photodetectors, and exploring new photoelectric materials and structures is one of the effective means; the two-dimensional perovskite material has a high absorption coefficient and extremely low dark current, while the two-dimensional transition metal disulfide has the advantages of high carrier mobility, wide light response range, etc. Combining the advantages of these two materials, the advantage of the two-dimensional material surface having no dangling bonds and being easy to stack with other two-dimensional materials to form a heterojunction is utilized, and by constructing a heterostructure, the advantages of the two-dimensional perovskite material having a high absorption coefficient and extremely low dark current and the two-dimensional transition metal disulfide having a high carrier mobility and a wide response band are combined, which greatly improves the performance of the photodetector, and has good performance in terms of light response rate, response time, and response range.

[0052] Based on this, the present application proposes a first embodiment of a two-dimensional organic-inorganic hybrid perovskite and molybdenum diselenide heterojunction photodetector, please refer to Figure 1 The two-dimensional organic-inorganic hybrid perovskite (C6H 13 The photodetector of the heterojunction of NH3)2PbI4(C6PI) and molybdenum diselenide includes: a substrate, an electrode layer, a photoelectric conversion part and a protective layer.

[0053] The electrode layer is located on one side of the substrate; the photoelectric conversion unit is arranged on the side of the electrode layer away from the substrate, the material of the photoelectric conversion unit includes two-dimensional organic-inorganic hybrid perovskite C6PI and molybdenum diselenide, and the protective layer is hexagonal boron nitride.

[0054] In this embodiment, C6PI and MoSe2 are used to construct a heterostructure. Due to the unique properties of C6PI, the photodetector has an extremely low dark current (10 -14 A). In addition, MoSe2 inhibits the photoluminescence of carriers in the heterojunction region, which is beneficial to the separation of electrons and holes in the junction region, inhibits the recombination of photogenerated electrons and holes, and greatly optimizes the performance of the device.

[0055] In a feasible embodiment, the material of the substrate includes at least one of Si, SiC and SOI (Silicon-On-Insulator). By using at least one of the above substrate materials, the service life of the C6PI and molybdenum diselenide heterostructure can be improved; and / or, the material of the electrode layer includes at least one of Au, Ag, Pd and Pt. By using at least one of the above electrode layer materials, a suitable electrode material can be selected according to different work functions.

[0056] In a feasible implementation manner, the photodetector further includes a dielectric layer and an adhesive layer, wherein: the dielectric layer is disposed between the substrate and the adhesive layer; and the adhesive layer is disposed between the electrode layer and the dielectric layer.

[0057] In a feasible implementation, the material of the dielectric layer includes at least one of SiO2, Al2O3 and HfO2; the material of the bonding layer includes at least one of Ti, Cr and Pd. Ti is a traditional bonding layer, the electrode obtained by Cr is more puncture-resistant and convenient for multiple tests, and Pd can be used to adjust the work function. All three are used as bonding layers, and can make the bonding contact performance of the electrode layer better.

[0058] This application combines C6PI with molybdenum diselenide to construct a heterostructure, combining the advantages of these two materials to obtain a high-performance, wide-band photodetector. The dark current of the heterojunction device is as low as 10 -14 A, the photoresponsivity reaches 11.5A / W, the response range is 450~900nm, the external quantum efficiency is 2417%, and the on / off ratio is 1.1×10 6 In addition, the device also has a fast time response (rise: τ r =6.85μs, fall: τ f =32.88μs). It can be used as a receiving device in the field of visible light communication and has great application potential in the field of photoelectric sensing.

[0059] The present application also provides a method for preparing a two-dimensional organic-inorganic hybrid perovskite and molybdenum diselenide heterojunction photoelectric detector, the preparation method comprising the following steps:

[0060] providing a substrate;

[0061] An electrode layer is prepared on the substrate by electron beam evaporation technology;

[0062] C6PI, molybdenum diselenide, and hexagonal boron nitride are sequentially transferred to the electrode layer to form a photoelectric conversion unit to obtain a photodetector.

[0063] In one feasible embodiment, C6PI, molybdenum diselenide and hexagonal boron nitride are sequentially transferred to the empty electrode by dry transfer.

[0064] In a feasible embodiment, the method of forming the photoelectric conversion part includes: obtaining C6PI, molybdenum diselenide and hexagonal boron nitride materials by a mechanical stripping method; transferring the obtained materials to a polydimethylsiloxane pad and selecting materials of target thickness; and transferring the obtained materials to an empty electrode in sequence by a dry transfer method.

[0065] Specifically, a few-layer samples were obtained by mechanical stripping. The obtained samples were transferred to a polydimethylsiloxane pad and samples of target thickness were selected. The selected samples were transferred to an empty electrode in sequence. In order to prevent the C6PI sample from degrading under environmental conditions, the entire process was completed in a glove box (argon environment) and covered with several layers of hexagonal boron nitride on the top layer for protection.

[0066] In a feasible embodiment, the synthesis process of C6PI crystals includes: C6H 13 The synthesis of NH3I reactant crystals and subsequent synthesis of C6PI crystals. This method is also applicable to the synthesis of other two-dimensional organic-inorganic perovskite materials in the same system, such as (C8H 17 NH3)2PbI4(C8PI).

[0067] In one possible embodiment, C6H 13 The synthesis process of NH3I crystals includes: adding 10mL ethanol and 2.32mL hexylamine into a beaker to form a mixture, which is then stored in an ice bath at 0℃. 2mL HI is added dropwise to the mixture and stirred for 2h to ensure complete reaction. The solvent is heated at 50℃ using a rotary evaporator until white ammonium salt powder appears and the solvent residue is completely evaporated. The ammonium salt powder is collected, washed with ether three times, transferred to a vacuum oven, and dried at 60℃ for 24h to obtain C6H 13 The synthesis process of C6PI crystals includes: 80 mg of prepared C6H 13 NH3I and 80.5 mg of lead iodide were dissolved in 2 mL of DMF, and dichloromethane was used as an antisolvent to assist the crystallization of C6PI. The formed crystals were washed with toluene and then dried to obtain C6PI crystals.

[0068] In a feasible implementation, the provided substrate is first cleaned with isopropanol, then cleaned with deionized water for a second time, and dried with nitrogen; the nitrogen-dried substrate is subjected to plasma treatment, wherein the plasma treatment time is 15 to 30 minutes; and / or the plasma treatment temperature is 20 to 40°C.

[0069] The technical solution of the present application is further described in detail below in conjunction with specific embodiments and drawings. It should be understood that the following embodiments are only used to explain the present application and are not used to limit the present application.

[0070] Example 1

[0071] like Figure 1 and Figure 2 As shown, the C6PI and MoSe heterojunction photodetector comprises:

[0072] Substrate, made of Si;

[0073] A dielectric layer, disposed between the substrate and the bonding layer, and made of SiO2;

[0074] A bonding layer, disposed between the dielectric layer and the electrode layer, and made of Ti;

[0075] The electrode layer is located on the side of the photoelectric conversion part away from the substrate, and the material is Au;

[0076] The photoelectric conversion unit is located on the electrode layer, and the materials of the photoelectric conversion unit include C6PI and molybdenum diselenide.

[0077] The protective layer is located on the upper surface of C6PI and molybdenum diselenide, and the material of the protective layer is hexagonal boron nitride.

[0078] Example 2

[0079] like Figure 11-13 As shown, the C8PI and InSe heterojunction photodetector includes:

[0080] Substrate, made of Si;

[0081] The dielectric layer is disposed between the substrate and the bonding layer, and the material is SiO2

[0082] A bonding layer, disposed between the dielectric layer and the electrode layer, and made of Cr;

[0083] The electrode layer is located on the side of the photoelectric conversion part away from the substrate, and the material is Au;

[0084] The photoelectric conversion unit is located on the electrode layer, and the materials of the photoelectric conversion unit include C8PI and indium selenide.

[0085] The protective layer is located on the upper surface of C8PI and indium selenide, and the material of the protective layer is hexagonal boron nitride.

[0086] Example 3

[0087] A photoelectric detector of a C6PI and molybdenum diselenide heterojunction, comprising:

[0088] Substrate, made of Si;

[0089] The dielectric layer is provided between the substrate and the bonding layer, and the material is: Al2O3

[0090] A bonding layer, disposed between the dielectric layer and the electrode layer, and made of Cr;

[0091] The electrode layer is located on the side of the photoelectric conversion part away from the substrate, and the material is Au;

[0092] Comparative Example 1

[0093] The material of the photoelectric conversion part of Comparative Example 1 is single C6PI, and the rest is the same as Example 1. For a single C6PI photodetector, the maximum on / off ratio of the device reaches 3 orders of magnitude, but the response range of the device is very small, about 450nm to 530nm.

[0094] Comparative Example 2

[0095] The material of the photoelectric conversion part of Comparative Example 2 is single molybdenum diselenide, and the rest is the same as Example 1. The response range of the single molybdenum diselenide photodetector is 450nm to 900nm, but the on / off ratio of the device is only one order of magnitude.

[0096] Performance Testing

[0097] The photodetector of the C6PI and molybdenum diselenide heterojunction of Example 1 was tested as follows:

[0098] Performance Characterization

[0099] Optical microscope images, such as Figure 3 As shown, the photoelectric conversion part is scanned under an atomic force microscope to obtain relevant thickness data. The thicknesses of C6PI and MoSe2 are 46.7nm and 8nm respectively. The atomic force microscope image, as shown in Figure 4 The PL spectrum of C6PI was measured by confocal Raman spectrometer, and the junction area and non-junction area were selected on the silicon oxide substrate and the metal electrode for testing. The results are shown in Figure 5 As shown. First, compare the difference between the junction area and the non-junction area. Whether on the silicon oxide electrode or the metal electrode, the PL peak of C6PI in the junction area is significantly smaller than that in the non-junction area. This is because the molybdenum diselenide in the junction area accelerates the transfer of photogenerated electron-hole pairs in C6PI and inhibits their recombination luminescence. Secondly, comparing the differences between different substrates, it can be found that the PL peak of C6PI on the metal electrode is much higher than the PL peak on silicon oxide. This is because the Fabry-Perot cavity (Fabry-Perot Cavity) formed between the material and the gold film enhances the light absorption of the material. The Raman spectrum test results are shown in Figure 6 As shown, Figure 6The characteristic peak in the graph is A of MoSe material. 1g .

[0100] Photoelectric performance test

[0101] The electrode contacted with C6PI was used as the drain electrode and the electrode contacted with MoSe2 was used as the source electrode, and the photoelectric performance of the device was measured. Figure 7 Using different wavelengths for a fixed optical power to explore the I of the device when illuminated ds -V ds When irradiated with 550nm laser, the device open circuit voltage is 0.55V and the short circuit current is 1.32×10 -12 A. Device I ds -V ds The curve does not pass through the origin, indicating the existence of a self-driving phenomenon, that is, optical signal detection can be achieved without external voltage supply, which can significantly reduce power consumption in large-scale integrated applications. Figure 8 The response characteristics of the device at different wavelengths. The response range of the detector is 450 to 850nm, covering visible light to near infrared. The device has the highest responsivity at 800nm ​​wavelength, which is 11.5A / W; followed by 700nm, where the responsivity is 11.1A / W.

[0102] like Fig. 9 As shown in the figure, the spatial distribution of the photocurrent in the device is characterized by using the photocurrent scanning test platform. The C6PI end of the device is powered by a signal generator, and the other end is connected to an amplifier. The amplifier converts the current signal into a voltage signal and inputs it into the controller. The device was tested under the irradiation of 532nm and 633nm lasers, and the photocurrent area scanning images at bias voltages of 0V and 1V were respectively tested. The two white dotted lines in the figure are the boundaries of the metal electrodes, the green dotted line is the area of ​​the molybdenum diselenide material, and the orange dotted line is the C6PI area. It can be seen from the figure that the main area where the photocurrent is generated is the heterojunction area. This is because when the laser is incident on the junction area, the material absorbs light energy to generate photogenerated carriers, and the photogenerated carriers can be effectively separated and collected by the electrode.

[0103] like Fig.10 As shown, at V ds Bias voltage is 1V, V gs Under the condition of 0V, the device's τ is measured r =6.85μs, τ f =32.88μs, with a faster time response.

[0104] The above are only preferred embodiments of the present application, and are not intended to limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A two-dimensional organic-inorganic hybrid perovskite (C6H 13 A photodetector of a heterojunction of NH3)2PbI4(C6PI) and molybdenum diselenide (MoSe2), characterized in that: The photodetector comprises: substrate; An electrode layer, located on one side of the substrate; A photoelectric conversion unit is provided on a side of the electrode layer away from the substrate, wherein the material of the photoelectric conversion unit includes C6PI and molybdenum diselenide; The protective layer, made of hexagonal boron nitride, is located on the upper surface of C6PI and molybdenum diselenide to prevent the perovskite from oxidation and moisture absorption.

2. The photodetector according to claim 1, wherein: The photodetector further comprises a dielectric layer and an adhesive layer, wherein: The dielectric layer is disposed between the substrate and the bonding layer; the material of the dielectric layer includes at least one of SiO2, Al2O3 and HfO2; The bonding layer is arranged between the electrode layer and the dielectric layer; the material of the bonding layer includes at least one of Ti, Cr and Pd.

3. The photodetector according to claim 1 or 2, characterized in that: The material of the substrate includes at least one of Si, SiC and SOI (Silicon-On-Insulator); and / or the material of the electrode layer includes at least one of Au, Ag, Pd and Pt.

4. A method for preparing a photoelectric detector according to any one of claims 1 to 3, characterized in that: The following steps are involved: providing a substrate; An electrode layer is prepared on the substrate by electron beam evaporation technology; C6PI, molybdenum diselenide, and hexagonal boron nitride are sequentially transferred to the electrode layer to form a photoelectric conversion part and a protective layer to obtain a photodetector.

5. The preparation method according to claim 4, characterized in that: C6PI, MoSe and HBN were sequentially transferred to the empty electrode by dry transfer.

6. The preparation method according to claim 5, characterized in that: The method of forming the photoelectric conversion unit and the protective layer includes: C6PI, molybdenum diselenide and hexagonal boron nitride materials were obtained by mechanical exfoliation. The obtained material is transferred onto a polydimethylsiloxane pad, and the material of target thickness is selected; The obtained materials are transferred to the empty electrodes in sequence by dry transfer method.

7. The preparation method according to claim 5, characterized in that: The synthesis process of C6PI crystals includes: 80 mg C6H 13 NH3I and 80.5 mg of lead iodide were dissolved in 2 mL of N,N-dimethylformamide (DMF). Dichloromethane was used as an antisolvent to assist the crystallization of C6PI. The formed crystals were washed with toluene and then dried to obtain C6PI crystals.

8. The preparation method according to claim 7, characterized in that: C6H 13 The synthesis process of NH3I crystals includes: adding 10 mL of ethanol and 2.32 mL of hexylamine into a beaker to form a mixture, which is then stored in an ice bath at 0°C; adding HI dropwise into the mixture and stirring for 2 hours to obtain a solvent; heating the solvent at 50°C using a rotary evaporator until white ammonium salt powder appears and the solvent residue is completely evaporated; washing the ammonium salt powder with ether; and drying the washed ammonium salt powder in a vacuum oven at 60°C for 24 hours to obtain C6H 13 NH3I crystals.

9. The preparation method according to any one of claims 4 to 8, characterized in that: The provided substrate is first cleaned with isopropanol, then cleaned with deionized water for a second time, and dried with nitrogen; the nitrogen-dried substrate is subjected to plasma treatment.

10. The preparation method according to claim 9, characterized in that: The plasma treatment time is 15 to 30 minutes; and / or the plasma treatment temperature is 20 to 40°C.

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