Self-driven low-dimensional non-lead perovskite ultraviolet detector and preparation method thereof

Abstract

The invention belongs to the technical field of photoelectric detection, and relates to a self-driven low-dimensional non-lead perovskite ultraviolet detector which is based on an oxide semiconductor / low-dimensional perovskite II-type heterojunction and comprises a substrate, a patterned bottom electrode, an oxide semiconductor layer, a low-dimensional perovskite layer and a window top electrode. Patterns of the patterned bottom electrode and the window top electrode are complementary, and the patterned bottom electrode and the window top electrode are combined electrodes and comprise diffusion barrier layers which are in contact with the lower surface and the upper surface of the heterojunction respectively; and the window area is a light receiving area of the detector. The device is characterized in that the advantage that a heterojunction built-in electric field is beneficial to separation of photo-generated charges is combined, meanwhile, ultraviolet light can directly enter a light absorber, and transmission loss is avoided; a reverse solvent steam assisted gradient annealing technology and a positive solvent steam assisted gradient annealing technology are adopted, so that the high-quality perovskite-like thin film is obtained; and the diffusion barrier layer is utilized to simultaneously prevent ions from diffusing at two interfaces of the bottom electrode / the oxide and the perovskite-like material / the top electrode. The process is simple, and the device is fast in light response, stable and environment-friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of photoelectric detectors, and in particular to a self-driven low-dimensional non-lead perovskite ultraviolet detector and a preparation method thereof. Background Art

[0002] In recent years, in order to meet the needs of low power consumption of optoelectronic devices, self-driven photodetectors have been widely studied because they do not require external power. And the use of heterojunctions, Schottky junctions, etc., combined with vertical device structures, is the main method to achieve self-driven photodetection without external pressure. However, the commonly used vertical configuration inevitably involves a transparent conductive electrode layer, and the light to be measured will produce transmission loss in the transparent electrode layer before entering the light absorber. Although the light transmission loss is very small in the visible-infrared region, it has a very serious impact on ultraviolet light. For example, ITO (indium tin oxide) and FTO (fluorine-doped tin oxide) will greatly absorb short-wavelength (<~320nm) ultraviolet light, making self-driven ultraviolet detection, especially self-driven visible light blind ultraviolet detection, difficult to achieve. In addition, in lateral devices based on heterojunctions, in order to achieve self-driving, the electron and hole collection electrodes on the same side are usually in contact with only the two ends of the junction, and the light absorption layer generally needs to be patterned or micro-nanostructured. At present, these methods are complex to implement and are not conducive to the application of large-area integrated photosensitive chips.

[0003] In terms of materials, there are currently two main solutions for UV detectors; one is based on traditional narrow-bandgap materials such as crystalline silicon, which requires additional filtering to selectively absorb ultraviolet light. The other uses wide-bandgap materials such as silicon carbide and gallium nitride, which have a high UV / visible light suppression ratio. However, the material preparation cost is high, involves vacuum equipment, and is difficult to make flexible. Among wide-bandgap materials, wide-bandgap lead-based perovskites have good light absorption, can be prepared by solution method, and have fast device light response, but the stability of commonly used lead-based perovskites and the toxicity of lead are not conducive to practical applications.

[0004] Therefore, preparing a self-driven detector that is highly sensitive, low-cost, stable, environmentally friendly, and conducive to ultraviolet detection has become an application-oriented problem that needs to be solved. Summary of the invention

[0005] In view of the above problems existing in the prior art, the present invention provides a self-driven low-dimensional non-lead perovskite ultraviolet detector and a preparation method thereof. The present invention is implemented by the following technical solutions:

[0006] On one hand, the present invention provides a self-driven low-dimensional non-lead perovskite ultraviolet detector, which comprises, from bottom to top, a substrate, a patterned bottom electrode, an oxide semiconductor layer, a low-dimensional perovskite layer and a window top electrode;

[0007] The oxide semiconductor layer and the low-dimensional perovskite layer have opposite conductivity types, similar band gaps, and can form a type II heterojunction; the patterned bottom electrode and the window top electrode have complementary patterns, the patterned bottom electrode includes a window area, and the patterned bottom electrode completely overlaps with the vertical projection of the window area of ​​the patterned bottom electrode;

[0008] The patterned bottom electrode and the window top electrode are composite electrodes, both containing a diffusion barrier layer, and the diffusion barrier layers of the patterned bottom electrode and the window top electrode are in contact with the lower surface and upper surface of the type II heterojunction respectively; the window area is the light receiving area of ​​the ultraviolet detector, and ultraviolet light can be directly incident on the type II heterojunction from the window area.

[0009] Preferably, the low-dimensional perovskite material in the low-dimensional perovskite layer is selected from a Cs-Ag-I system or a Cs-Cu-I system, the Cs-Ag-I system includes CsAg2I3 and Cs3Ag2I5, and the Cs-Cu-I system includes CsCu2I3 and Cs3Cu2I5.

[0010] Preferably, the material of the oxide semiconductor layer is SnO2, ZnO, Ga2O3 or P-type NiO. x 、Cu2O.

[0011] Preferably, the thickness of the oxide semiconductor layer is 50-200 nm, and the thickness of the low-dimensional perovskite layer is 100-400 nm.

[0012] Preferably, the diffusion barrier layer comprises a conductive material that blocks ion diffusion, including titanium nitride, titanium or tantalum, and has a thickness of 1-10 nm.

[0013] Another aspect of the present invention provides a method for preparing a self-driven low-dimensional non-lead perovskite ultraviolet detector, which is used to prepare the self-driven low-dimensional non-lead perovskite ultraviolet detector described in any one of the above embodiments, and the preparation steps include:

[0014] S1: Selecting a substrate substrate and preparing a patterned bottom electrode on the substrate substrate;

[0015] S2: using the oxygen vacancy compensation technology of hydrogen peroxide pyrolysis to prepare an oxide semiconductor layer on the surface of the substrate substrate covered with the patterned bottom electrode;

[0016] S3: using reverse and forward solvent vapor assisted gradient annealing techniques, preparing a low-dimensional perovskite-like layer on the oxide semiconductor layer to form a type II heterojunction;

[0017] S4: Prepare a window top electrode on the low-dimensional perovskite layer.

[0018] Preferably, in step S2, the preparation of the oxide semiconductor layer specifically includes:

[0019] An oxide precursor solution is prepared and hydrogen peroxide with a concentration of 1%-8% is added, wherein the oxide precursor solution includes an oxide nanoparticle dispersion or a metal salt solution that can be pyrolyzed to generate oxides, and the concentration is 1%-10%; the oxide semiconductor layer is prepared on the surface of a substrate substrate covered with a patterned bottom electrode by spin coating and annealing (100-150°C).

[0020] Preferably, in step S3, the preparation of the low-dimensional perovskite layer specifically includes:

[0021] Preparing a perovskite precursor solution and spin coating it on the oxide semiconductor layer;

[0022] annealing the spin-coated film at a first temperature in an anti-solvent vapor environment to obtain a first annealed film;

[0023] The film after the first annealing is annealed at a second temperature in a positive solvent vapor environment to obtain a film after the second annealing, wherein the second temperature is greater than the first temperature, the first temperature is 50-90°C, and the second temperature is 100-200°C.

[0024] Preferably, the anti-solvent is volatile and difficult to dissolve perovskite and its precursor, including methanol and isopropanol. The positive solvent is a solvent that can dissolve perovskite, including tetrahydrofuran, N,N-dimethylformamide or dimethyl sulfoxide.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1) Compared with general lateral devices, the self-driven ultraviolet detector provided by the present invention has carrier collection electrodes on the upper and lower sides of the light absorber (heterojunction in the present invention), and does not require a patterned light absorption layer. It can fully utilize the built-in electric field of the heterojunction for longitudinal carrier separation, which helps to improve the light response rate. At the same time, compared with general vertical devices, in the device structure of the present invention, ultraviolet light can be directly incident on the light absorber, avoiding the transmission loss of short-wavelength ultraviolet light through the transparent electrode in general vertical devices.

[0027] 2) The bottom and top electrodes of the self-driven ultraviolet detector provided by the present invention are both composite electrodes containing diffusion barrier layers, and the diffusion barrier layers are directly in contact with the upper and lower surfaces of the heterojunction, while blocking ions from diffusing at the interfaces of the bottom electrode / oxide and the perovskite / top electrode, which is beneficial to the stability of the device.

[0028] 3) The self-driven ultraviolet detector preparation method provided by the present invention uses reverse and positive solvent vapor-assisted gradient annealing technology to prepare the perovskite-like layer, which promotes the rapid formation of the transition state and the regulation of its crystallization process, as well as dissolution-recrystallization to improve the quality of the perovskite film.

[0029] 4) In the method for preparing a self-driven ultraviolet detector provided by the present invention, the oxide semiconductor layer utilizes oxygen vacancy compensation by thermal decomposition of hydrogen peroxide to suppress the continuous photoconductivity effect, thereby improving the ultraviolet detection performance.

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the structure of a self-driven low-dimensional non-lead perovskite ultraviolet detector provided by an embodiment of the present invention;

[0032] Figure 2 It is a schematic flow chart of a method for preparing a self-driven low-dimensional non-lead perovskite ultraviolet detector provided by an embodiment of the present invention;

[0033] Figure 3 It is a process schematic diagram of a method for preparing a self-driven low-dimensional non-lead perovskite ultraviolet detector provided by an embodiment of the present invention;

[0034] Figure 4 is a SEM image of a CsAg2I3 low-dimensional perovskite layer prepared by the preparation method provided by an embodiment of the present invention;

[0035] Figure 5 is an XRD diagram of a CsAg2I3 low-dimensional perovskite layer prepared by the preparation method provided by an embodiment of the present invention;

[0036] Figure 6 It is a dark current diagram of a self-driven low-dimensional non-lead perovskite ultraviolet detector prepared by the preparation method provided by an embodiment of the present invention;

[0037] Figure 7 It is an IV switch response diagram of a self-driven low-dimensional non-lead perovskite ultraviolet detector prepared by the preparation method provided by an embodiment of the present invention;

[0038] Figure 8 The diagram is a relationship between the photoresponsivity and wavelength of a self-driven low-dimensional non-lead perovskite ultraviolet detector prepared by the preparation method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0039] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, specific embodiments are described in detail with reference to the accompanying drawings.

[0040] See also Figure 1 , Figure 1 It is a structural schematic diagram of a self-driven low-dimensional non-lead perovskite ultraviolet detector provided by an embodiment of the present invention, which includes, from bottom to top, a substrate substrate 1, a patterned bottom electrode 2, an oxide semiconductor layer 3, a low-dimensional perovskite layer 4, and a window top electrode 5; wherein the oxide semiconductor layer 3 and the low-dimensional perovskite layer 4 have opposite conductivity types, forming a type II heterojunction; the pattern of the bottom electrode 2 is complementary to the pattern of the window top electrode 5. Further, the pattern of the bottom electrode 2 is a closed figure, including a square and a circle, and completely overlaps with the vertical projection of the window area 6. The window area 6 is the effective light-receiving area of ​​the ultraviolet detector. Ultraviolet light 7 can be directly incident on the heterojunction from the window area 6.

[0041] The low-dimensional non-lead perovskite material used in the embodiment is selected from the Cs-Ag-I system (including CsAg2I3, Cs3Ag2I5) or the Cs-Cu-I system (including CsCu2I3, Cs3Cu2I5). These materials have the advantages of high light absorption coefficient and solution preparation of common lead-based perovskite materials, and at the same time have the characteristics of stability, wide band gap and environmental protection, which is more conducive to ultraviolet detection. Different perovskite materials need to use oxide semiconductors with similar band gaps and opposite conductivity types to further balance and promote the separation and transport of electrons and holes at the interface.

[0042] In this embodiment, the material of the oxide semiconductor layer 3 needs to have a band gap close to that of the selected low-dimensional perovskite material and an opposite conductivity type, and can be selected from N-type SnO2, ZnO, Ga2O3 or P-type NiO x Or Cu2O. The thickness of the oxide semiconductor layer 3 is 50-200nm, the thickness of the low-dimensional perovskite layer 4 is 100-400nm, and the thickness of the bottom electrode 2 and the top electrode 5 is 80-150nm.

[0043] Furthermore, the patterned bottom electrode 2 and the window top electrode 5 are both metal composite electrodes containing a diffusion barrier layer of an affinity heterojunction material. The bottom electrode is first deposited with a single metal electrode and then a diffusion barrier layer to form a composite electrode; the top electrode is first deposited with a diffusion barrier layer and then a single metal electrode to form a composite electrode. The diffusion barrier layer can be selected from titanium nitride, titanium, and tantalum, and the diffusion barrier layer is used to prevent ion diffusion at the device interface.

[0044] The present invention also provides a method for preparing a self-driven low-dimensional non-lead perovskite ultraviolet detector, see Figure 2 and Figure 3 , the preparation method comprises the following steps:

[0045] S1: Select a substrate substrate 1 and prepare a patterned bottom electrode 2 on the substrate substrate 1.

[0046] A substrate substrate 1 with a clean surface is selected, and a patterned bottom electrode 2 is prepared on the substrate substrate 1 by hollow mask combined with evaporation, or the electrode is prepared by lift-off process. Specifically, a uniform photoresist is coated on the substrate substrate 1 by a coating machine spin coating and annealing process, and the thickness of the photoresist is regulated by the spin coating speed, and then the photoresist is patterned by exposure and development, and then the electrode is deposited, the coating is removed, and the patterned bottom electrode 2 is prepared by the steps of drying. The electrode deposition sequence is to first deposit a single metal electrode and then deposit a diffusion barrier layer to form a composite electrode.

[0047] Optionally, the photolithography process uses ultraviolet lithography, the photoresist is selected from positive photoresist or negative photoresist, and the thickness of the photoresist is 1-3 μm.

[0048] S2: preparing an oxide semiconductor layer 3 on the surface of the substrate covered with the patterned bottom electrode 2.

[0049] An oxide precursor solution is prepared and hydrogen peroxide with a concentration of 1%-8% is added, wherein the oxide precursor solution includes an oxide nanoparticle dispersion or a metal salt solution that can be pyrolyzed to generate an oxide, such as tin chloride, hydrated gallium nitrate, etc., and the solution concentration is 1%-10%; the oxide semiconductor layer 3 is prepared by spin coating and annealing (100-150° C.). The hydrogen peroxide therein is pyrolyzed to reduce and inhibit oxygen vacancy defects in the oxide film.

[0050] S3: preparing a perovskite-like layer 4 on the oxide semiconductor layer 3 to form a type II heterojunction.

[0051] A perovskite precursor solution is prepared, such as a solution of CsI and AgI in a molar ratio of 1:2 for synthesizing CsAg2I3. The solution concentration can be selected to be 0.1-1 mol / L; then the perovskite precursor solution is spin-coated on the oxide semiconductor layer 3. Then, an anti-solvent and positive solvent vapor-assisted gradient annealing process is performed to prepare a low-dimensional perovskite layer 4. Specifically, an anti-solvent is first dripped on a hot stage and a lid (cover) is added to form anti-solvent vapor, and the sample of the spin-coated perovskite precursor solution is annealed in an anti-solvent vapor environment and at a first temperature (50-90°C, i.e., the low temperature in the gradient annealing). Subsequently, the film after the first annealing is annealed in a positive solvent vapor environment and at a second temperature (100-200°C, i.e., the high temperature in the gradient annealing) to obtain a film after the second annealing. Compared with the conventional gradient annealing process, the reverse and forward solvent vapor-assisted gradient annealing process not only further accelerates the formation of the perovskite-like intermediate phase in the low-temperature annealing process (the intermediate phase represents the state of the solvent-coordinated precursor complex before crystallization), but also promotes the dissolution-recrystallization process in the high-temperature annealing process, thereby optimizing the crystal orientation and improving the quality of perovskite-like film formation.

[0052] Optionally, the anti-solvent needs to be volatile at room temperature, including methanol, isopropanol or ethanol; the positive solvent is a polar solvent, which can be tetrahydrofuran, N,N-dimethylformamide or dimethyl sulfoxide.

[0053] S4: preparing a window top electrode 5 on the low-dimensional perovskite layer 4 .

[0054] The window top electrode 5 which is complementary to the bottom electrode 2 pattern is prepared by the same process as the bottom electrode 2 in step 1. The electrode deposition sequence is different from step S1, that is, a diffusion barrier layer is deposited first and then a single metal electrode is deposited to form a composite electrode. The effective contact area of ​​the top electrode 5 is consistent with that of the bottom electrode 2 to balance the effective collection area of ​​electrons and holes. The window area of ​​the top electrode 5 is the light receiving area of ​​the device.

[0055] Embodiment 1

[0056] This embodiment provides a method for preparing a self-driven low-dimensional non-lead perovskite ultraviolet detector based on a heterojunction SnO2 / 1D-CsAg2I3, the preparation method comprising:

[0057] S1: Select a flat glass substrate, clean it with acetone, alcohol and deionized water ultrasonically for 5 minutes, blow it dry with a nitrogen gun, bake it on a hot plate at 180°C for 5 minutes to obtain a clean substrate 1, and treat it with oxygen plasma for 3 minutes;

[0058] S2: A square patterned bottom electrode with a size of 3×3 mm is prepared on a clean substrate 1 by evaporation combined with a hollow hard mask process. The material is 100 nm Au / 3 nm Ti (Au is evaporated first, then Ti is evaporated), and the evaporation rate is controlled at 0.2 nm / s.

[0059] S3: Prepare a 3% SnCl2 aqueous solution as a precursor, add 1% to 8% hydrogen peroxide, and prepare an oxide SnO2 semiconductor polycrystalline thin film by solution spin coating-annealing process, with a spin coating speed of 3000 rpm, a time of 30 s, an annealing temperature of 170°C, and a time of 60 min to form an oxide semiconductor layer 3.

[0060] S4: Prepare 0.5 mol / L perovskite precursor solution, in which the molar ratio of CsI and AgI is 1:2, dissolve in dimethyl sulfoxide solvent, and prepare perovskite film by spin coating and anti-solvent (IPA) and positive solvent (THF) vapor-assisted gradient annealing, wherein the spin coating rate is 500 rpm for 10 s, and then 2000 rpm for 30 s. Anti-solvent vapor-assisted low-temperature (50°C) annealing time is 10 min, and positive solvent vapor-assisted high-temperature (100°C) annealing time is 60 min, forming a low-dimensional perovskite layer 4.

[0061] S5: A window top electrode 5 complementary to the pattern of the bottom electrode 2 is prepared by thermal evaporation combined with a hollow hard mask process. The size of the window area 6 is consistent with the pattern of the bottom electrode 2, and the outer size of the top electrode 5 is 4.3×4.3 mm, so that the effective contact area of ​​the electrode 5 is consistent with that of the bottom electrode. The electrode material is 5nm Ti / 100nm Au (Ti is evaporated first, and then Au is evaporated).

[0062] See also Figures 4 to 8 , Figure 4 This is a SEM image of a CsAg2I3 low-dimensional perovskite layer prepared by the preparation method provided in an embodiment of the present invention. It can be seen that a smooth and flat film is obtained. Figure 5 The XRD diagram of the CsAg2I3 low-dimensional perovskite layer prepared by the preparation method provided in the embodiment of the present invention, the strong XRD peak and the low half-width indicate excellent crystallization. Figure 6 It is a dark current diagram of a self-driven low-dimensional non-lead perovskite ultraviolet detector prepared by the preparation method provided by an embodiment of the present invention, which has the lowest dark current at 0V, so that the detector has a higher detection rate without an external voltage (0V). Figure 7 This is a switch response diagram of a self-driven low-dimensional non-lead perovskite ultraviolet detector IV prepared by the preparation method provided by an embodiment of the present invention, and its light response time is 46 / 49 μs. Figure 8 This is a graph showing the relationship between the light responsivity and wavelength of a self-driven low-dimensional non-lead perovskite ultraviolet detector prepared by the preparation method provided by the embodiment of the present invention. It can be seen that the responsivity can reach 0.11A / W under 300nm ultraviolet light, and it has a high inhibitory effect on visible light and infrared bands. And the detection rate can reach ~10 12 Jones.

[0063] Embodiment 2

[0064] On the basis of Example 1, this embodiment provides a method for preparing a self-driven low-dimensional non-lead perovskite ultraviolet detector based on a heterojunction Ga2O3 / 0D-Cs3Cu2I5, the preparation method comprising:

[0065] S1: Select a flat glass substrate, clean it with acetone, alcohol and deionized water ultrasonically for 5 minutes, blow it dry with a nitrogen gun, bake it on a hot plate at 180°C for 5 minutes to get a clean substrate, and treat it with oxygen plasma for 3 minutes;

[0066] S2: A square bottom electrode pattern was prepared on a clean substrate by evaporation combined with a hollow hard mask process. The electrode size was 3×3 mm, the material was 100 nm Au / 3 nm Ti (Au was evaporated first, then Ti), and the evaporation rate was controlled at 0.2 nm / s.

[0067] S3: Prepare a 2% precursor hydrated gallium nitrate / ethylene glycol methyl ethyl ether solution, add 3% hydrogen peroxide, and combine the spin coating-annealing process to prepare Ga2O3 semiconductor polycrystalline thin film, the spin coating speed is 6000rpm, the time is 30s, the annealing temperature is 500℃, and the time is 1.5h.

[0068] S4: Prepare a 4% perovskite precursor solution, in which the molar ratio of CsI and CuI is 3:2, and dissolve it in dimethyl sulfoxide solvent. Prepare the perovskite film by spin coating and anti-solvent (IPA) and positive solvent (THF) vapor-assisted gradient annealing, wherein the anti-solvent vapor-assisted low-temperature (70°C) annealing time is 10 min, and the positive solvent vapor-assisted high-temperature (160°C) annealing time is 60 min, to form Cs3Cu2I5.

[0069] S5: Use thermal evaporation combined with hollow hard mask process to prepare the top electrode window pattern complementary to the bottom electrode. The size of the area inside the window is consistent with that of the bottom electrode, with an outer size of 4.3×4.3 mm, and the electrode is 5nm Ti / 100nm Au (Ti is evaporated first, then Au is evaporated).

[0070] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, any modifications made without departing from the concept of the present invention should be deemed to belong to the protection scope of the present invention.

Claims

1. A self-driven low-dimensional non-lead perovskite ultraviolet detector, characterized in that: From bottom to top, it includes a substrate, a patterned bottom electrode, an oxide semiconductor layer, a low-dimensional perovskite layer and a window top electrode; The materials of the oxide semiconductor layer and the low-dimensional perovskite layer are wide bandgap materials with similar bandgaps, opposite conductivity types, and can form a type II heterojunction; the patterned bottom electrode and the window top electrode have complementary patterns, and the vertical projections of the patterned bottom electrode and the window area of ​​the window top electrode completely overlap; The patterned bottom electrode is a single metal layer / diffusion barrier layer composite electrode, wherein the diffusion barrier layer is in contact with the oxide semiconductor layer; the window top electrode is a diffusion barrier layer / single metal layer composite electrode, wherein the diffusion barrier layer is in contact with the low-dimensional perovskite layer; the window area is the light receiving area of ​​the ultraviolet detector, and ultraviolet light can be directly incident from the window area to the type II heterojunction.

2. The self-driven low-dimensional non-lead perovskite ultraviolet detector according to claim 1, characterized in that: The low-dimensional perovskite material in the low-dimensional perovskite layer is selected from a Cs-Ag-I system or a Cs-Cu-I system, the Cs-Ag-I system includes CsAg2I3 and Cs3Ag2I5, and the Cs-Cu-I system includes CsCu2I3 and Cs3Cu2I5.

3. The self-driven low-dimensional non-lead perovskite ultraviolet detector according to claim 1, characterized in that: The material of the oxide semiconductor layer is SnO2, ZnO, Ga2O3, NiO x or Cu2O.

4. The self-driven low-dimensional non-lead perovskite ultraviolet detector according to claim 1, characterized in that: The thickness of the oxide semiconductor layer is 50-200 nm, and the thickness of the low-dimensional perovskite layer is 100-400 nm.

5. The self-driven low-dimensional non-lead perovskite ultraviolet detector according to claim 1, characterized in that: The diffusion barrier layer has a conductive material that blocks ion diffusion, including titanium nitride, titanium or tantalum, and has a thickness of 1-10 nm.

6. A method for preparing a self-driven low-dimensional non-lead perovskite ultraviolet detector, characterized in that: For preparing a self-driven low-dimensional non-lead perovskite ultraviolet detector according to any one of claims 1 to 5, the preparation method comprising: S1: Selecting a substrate substrate and preparing a patterned bottom electrode on the substrate substrate; S2: using the oxygen vacancy compensation technology of hydrogen peroxide pyrolysis to prepare an oxide semiconductor layer on the surface of the substrate substrate covered with the patterned bottom electrode; S3: using reverse and forward solvent vapor assisted gradient annealing techniques, preparing a low-dimensional perovskite-like layer on the oxide semiconductor layer to form a type II heterojunction; S4: preparing a window top electrode on the low-dimensional perovskite layer.

7. The method for preparing the self-driven low-dimensional non-lead perovskite ultraviolet detector according to claim 6, characterized in that: The method comprises: using the oxygen vacancy compensation technology of hydrogen peroxide pyrolysis to prepare an oxide semiconductor layer on the surface of the substrate substrate covered with the patterned bottom electrode, comprising: An oxide precursor solution is prepared and hydrogen peroxide with a concentration of 1%-8% is added, wherein the oxide precursor solution includes an oxide nanoparticle dispersion or a metal salt solution that can be pyrolyzed to generate oxides, and the concentration is 1%-10%; the oxide semiconductor layer is prepared on the surface of a substrate substrate covered with a patterned bottom electrode by spin coating and annealing processes, wherein the annealing temperature is 100-150°C.

8. The method for preparing the self-driven low-dimensional non-lead perovskite ultraviolet detector according to claim 6, characterized in that: Using reverse and forward solvent vapor assisted gradient annealing technology, a low-dimensional perovskite-like layer is prepared on the oxide semiconductor layer to form a type II heterojunction, comprising: Preparing a perovskite precursor solution and spin coating it on the oxide semiconductor layer; annealing the spin-coated film at a first temperature in an anti-solvent vapor environment to obtain a first annealed film; The film after the first annealing is annealed at a second temperature in a positive solvent vapor environment to obtain a film after the second annealing, wherein the second temperature is greater than the first temperature, the first temperature is 50-90°C, and the second temperature is 100-200°C.

9. The method for preparing the self-driven low-dimensional non-lead perovskite ultraviolet detector according to claim 8, characterized in that: The anti-solvent is volatile and difficult to dissolve perovskite and its precursor, including methanol and isopropanol. The positive solvent is a solvent that can dissolve perovskite, including tetrahydrofuran, N,N-dimethylformamide or dimethyl sulfoxide.

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