A solvent-thermal treated two-dimensional / three-dimensional perovskite heterojunction, a preparation method and applications thereof

Abstract

The application provides a kind of solvent thermal treatment two-dimensional / three-dimensional perovskite heterojunction, preparation method and application.The application prepares a two-dimensional perovskite passivation layer on the surface of three-dimensional lead halide perovskite film, and then carries out solvent thermal treatment by AX / IPA mixed steam, eliminates the lead halide by-product at the interface of two-dimensional / three-dimensional perovskite heterojunction, and increases the halide octahedral layer number in two-dimensional perovskite.The application not only effectively reduces the non-radiation load center on the surface of the film, enhances the passivation effect of two-dimensional perovskite, and improves the photoelectric conversion efficiency;But also enhances the out-of-plane transport capacity of carriers, improves the vertical conductivity, reduces the current loss, improves the responsivity and detection rate of the device;Solves the problem of solvent incompatibility in the two-dimensional / three-dimensional perovskite heterojunction prepared by traditional solution method, realizes the effective passivation of perovskite film surface defects, and provides strong technical support for preparing high-performance stable perovskite film photoelectric devices.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optoelectronic devices, in particular to a solvent-thermal treated two-dimensional / three-dimensional perovskite heterojunction, a preparation method and applications. BACKGROUND

[0002] In recent years, three-dimensional halide lead perovskite materials have attracted extensive attention due to their excellent physical properties, such as high light absorption coefficient, low-temperature solution processability, long carrier diffusion length, long carrier lifetime, etc., and are considered as important semiconductor materials for preparing high-performance optoelectronic devices. However, a large number of surface defects lead to serious non-radiative recombination loss, which greatly reduces the photoelectric performance and stability of the device. It is very important to passivate the surface defects of three-dimensional halide lead perovskite thin films with two-dimensional perovskite for the manufacture of high-performance optoelectronic devices. However, the incompatibility of solvents usually leads to the formation of halide lead by-products in the prepared two-dimensional / three-dimensional perovskite heterojunction, thereby preventing the two-dimensional perovskite from exerting its passivation potential. Therefore, it is crucial to repair the halide lead by-products in the two-dimensional / three-dimensional perovskite heterojunction and inhibit the defect states for the preparation of high-performance and stable optoelectronic devices. SUMMARY

[0003] In view of some deficiencies in the prior art, the present application provides a solvent-thermal treated two-dimensional / three-dimensional perovskite heterojunction, a preparation method and applications. Through solvent-thermal treatment, the present application not only effectively reduces the non-radiative recombination centers on the surface of the thin film, enhances the passivation effect of the two-dimensional perovskite, and improves the photoelectric conversion efficiency; but also enhances the out-of-plane transport ability of the carriers, improves the vertical conductivity, reduces the current loss, and improves the responsivity and detectivity of the device; solves the problem of solvent incompatibility in the two-dimensional / three-dimensional perovskite heterojunction prepared by the traditional solution method, and realizes effective passivation of the surface defects of the perovskite thin film.

[0004] The present application provides a preparation method of a solvent-thermal treated two-dimensional / three-dimensional perovskite heterojunction. A two-dimensional perovskite passivation layer is prepared on the surface of a three-dimensional halide lead perovskite thin film to obtain a two-dimensional / three-dimensional perovskite heterojunction, and the two-dimensional / three-dimensional perovskite heterojunction is subjected to solvent-thermal treatment: in a closed space, AX powder is placed on a hot stage at 130-180 ℃, the two-dimensional / three-dimensional perovskite heterojunction and isopropanol (IPA) are placed on a platform at 60-100 ℃, an atmosphere filled with AX / IPA mixed vapor is formed, and the atmosphere is maintained for 5-25 minutes to obtain a solvent-thermal treated two-dimensional / three-dimensional perovskite heterojunction; wherein A is a methylamine cation CH3NH3 + (MA + ) or a formamidinium cation H2NCHNH2 + (FA + ), and X is a chloride anion Cl - , a bromide anion Br- or iodide anion I - .

[0005] Further, the two-dimensional / three-dimensional perovskite heterojunction comprises a three-dimensional lead halide perovskite film APbX3 and a two-dimensional perovskite passivation layer L'2A n-1 Pb n X 3n+1 ; wherein the short-chain cation A is a methylamine cation CH3NH3 + (MA + ) or formamidinium cation H2NCHNH2 + (FA + ), the halide anion X is chloride anion Cl - , bromide anion Br - or iodide anion I - , the long-chain organic cation L' is butylamine cation CH3CH2CH2CH2NH3 + (BA + ) or phenylethylamine cation C6H5CH2CH2NH3 + (PEA + ), and n is the number of PbX6 octahedra wrapped by the long-chain organic cation.

[0006] Further, the preparation of the two-dimensional / three-dimensional perovskite heterojunction comprises the following steps:

[0007] Step 1. Preparation of a three-dimensional lead halide perovskite film:

[0008] Prepare a three-dimensional lead halide perovskite precursor solution, mix AX, PbX2 and ZIF-67 powder in a molar ratio of 1:1:0.01-0.03, dissolve in a mixed solvent of N-N dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) to form a three-dimensional lead halide perovskite precursor solution of 0.6-1.5 mol / L;

[0009] Prepare a lead halide seed layer solution, dissolve PbX2 in a mixed solvent of N-N dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) to form a lead halide seed layer solution of 0.3-1.3 mol / L;

[0010] Provide a clean substrate and perform surface treatment; prepare a lead halide seed layer on the substrate by one-step spin coating; anneal at 65-85 ℃ for 1-10 minutes to obtain a lead halide seed layer film;

[0011] Prepare a three-dimensional lead halide perovskite film on the lead halide seed layer by one-step anti-solvent crystallization method; then anneal at 65-85 ℃ for 1-4 minutes and at 90-110 ℃ for 7-15 minutes to dry the solvent, to obtain a three-dimensional lead halide perovskite film;

[0012] Step 2. Preparation of two-dimensional perovskite passivation layer:

[0013] Prepare a two-dimensional perovskite cation solution, weigh a certain amount of L'X powder and dissolve it into isopropyl alcohol (IPA) to form a two-dimensional perovskite cation solution with a concentration of 2-20 mg / ml;

[0014] Spin-coat the prepared two-dimensional perovskite cation solution on the surface of the three-dimensional lead halide perovskite, and anneal at 70-100°C for 3-10 minutes to obtain a two-dimensional / three-dimensional perovskite heterojunction.

[0015] Further, the volume ratio of the mixed solvent of N-N dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in the perovskite precursor solution of step 1 is 3:1-8:1, and the volume ratio of the mixed solvent of N-N dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in the lead halide seed layer solution is 10:1-19:1.

[0016] Further, the substrate in step 1 is FTO conductive glass or ITO conductive glass.

[0017] Further, the processing steps of the substrate in step 1 include:

[0018] Step A1. Ultrasonically clean the substrate by sequentially placing it in acetone, anhydrous ethanol, and deionized water to remove impurities and oil on the surface of the substrate, with each ultrasonic cleaning time being 4-9 minutes;

[0019] Step A2. Blow off the residual water droplets on the surface of the conductive glass substrate with nitrogen;

[0020] Step A3. Dry the substrate in a drying oven at 50-70°C;

[0021] Step A4. Plasma clean for 2-4 minutes or ultraviolet ozone clean for 5-15 minutes to increase the hydrophilicity of the substrate.

[0022] Further, in step 1, the anti-solvent used in the anti-solvent crystallization method is one or two of toluene, ethyl acetate, and chlorobenzene.

[0023] Further, the solvothermal treatment process is to use a glassware inverted on a hot stage at 130-180°C to construct an enclosed space, and use a polytetrafluoroethylene heat insulation block placed on the hot stage to construct a platform at 60-100°C, and the two-dimensional / three-dimensional perovskite heterojunction and isopropyl alcohol (IPA) are placed on the polytetrafluoroethylene heat insulation block.

[0024] The two-dimensional / three-dimensional perovskite heterojunction prepared by the preparation method.

[0025] The application of the two-dimensional / three-dimensional perovskite heterojunction is characterized in being used for a photoelectric detection device or a photoelectric conversion device.

[0026] The present application has the following advantages:

[0027] The lead halide thin film prepared by the solution method has a large number of elemental vacancy defects and grain boundary defects, such as elemental vacancy defects and grain boundary defects. These defects are main non-radiative recombination centers, which will cause the recombination of photo-generated carriers, dissipate in the form of phonon or heat, thereby reducing the luminous intensity of fluorescence and the photoelectric conversion efficiency. The present application first prepares a two-dimensional perovskite passivation layer on the surface of the three-dimensional lead halide perovskite thin film, and passivates the defect states on the surface of the three-dimensional lead halide perovskite thin film by using long-chain organic cations. Subsequently, AX / IPA vapor is used for solvothermal treatment, and the AX / IPA vapor can penetrate into the two-dimensional / three-dimensional perovskite heterojunction and the lead halide by-products at the two-dimensional / three-dimensional perovskite heterojunction interface to perform an intercalation reaction, i.e. AX+PbX2→APbX3, thereby converting the lead halide by-products into APbX3, effectively reducing the non-radiative recombination centers on the surface of the thin film, enhancing the passivation effect of the two-dimensional perovskite, and improving the photoelectric conversion efficiency of the material, the sensitivity and weak light detection capability of the photoelectric detector.

[0028] Meanwhile, the number of PbX6 octahedron layers, i.e. the n value, in the two-dimensional perovskite is increased to m+n due to the intercalation reaction: L'2A n-1 Pb n X 3n+1 +m(AX)+m(PbX2)→L'2A (m+n)-1 Pb m+n X 3(m+n)+1 , which weakens the quantum confinement effect in the vertical direction, enhances the out-of-plane transport capability of the carriers, improves the conductivity in the vertical direction, reduces the current loss, and improves the responsivity and detection rate of the device.

[0029] The present application solves the problem of solvent incompatibility in the two-dimensional / three-dimensional perovskite heterojunction prepared by the traditional solution method, effectively passivates the defects on the surface of the perovskite thin film, provides strong technical support for preparing high-performance and stable perovskite thin film photoelectric devices such as solar cells, photoelectric detectors and light-emitting diodes, and has important application value. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a schematic diagram of solvothermal treatment of the two-dimensional / three-dimensional perovskite heterojunction.

[0031] Figure 2 is a scanning electron microscope (SEM) image of the perovskite thin film.

[0032] Figure 3 is the X-ray diffraction (XRD) test result figure of the perovskite thin film.

[0033] Figure 4 is the steady-state fluorescence (PL) intensity test result figure of the perovskite thin film.

[0034] Figure 5 is the current-voltage (I-V) curve test result figure of the perovskite thin film photodetector.

[0035] Figure 6 is the responsivity (R) and detectivity (D*) test result figure of the perovskite thin film photodetector.

[0036] In the figure:

[0037] 1 is a two-dimensional / three-dimensional perovskite heterojunction, 2 is isopropanol, 3 is a polytetrafluoroethylene heat insulation block, 4 is a glass culture dish, 5 is CH3NH3I powder, and 6 is a hot stage. DETAILED DESCRIPTION

[0038] The application will be further described below in conjunction with the drawings and specific examples, but the scope of protection of the application is not limited thereto. EMBODIMENT

[0039] (1) Substrate cleaning and surface treatment: Take 15 mm x 15 mm x 1.1 mm ITO conductive glass; ultrasonically clean the conductive substrate with acetone, anhydrous ethanol and deionized water in turn, remove oil stains and impurities on the surface of the substrate, and each ultrasonic time is 5 minutes; nitrogen is blown to remove water droplets on the conductive substrate, and a drying oven is used for drying at 50 ℃. Then, plasma cleaning is performed for 200 seconds to increase the hydrophilicity of the substrate surface.

[0040] (2) Configuration of three-dimensional lead halide perovskite precursor solution: Methylammonium iodide (MAI), lead iodide (PbI2) powder and ZIF-67 powder are mixed according to a molar ratio of 1:1:0.03, and dissolved in a mixed solution of N-N dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in a volume ratio of 4:1 to obtain a MAPbI3 precursor solution with a concentration of 1.3 mol / L.

[0041] (3) Configuration of lead halide seed layer solution: PbI2 is dissolved in a mixed solvent of N-N dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in a volume ratio of 19:1 to form a 1.3 mol / L lead iodide seed layer solution.

[0042] (4) Configuration of two-dimensional perovskite cation solution: A certain amount of butylammonium iodide (BAI) powder is dissolved in isopropanol (IPA) to form a BAI solution with a concentration of 5 mg / ml.

[0043] (5) Take 40 μl of lead iodide seed layer solution and drop it onto the ITO substrate, spin at 5000 r / min for 30 s, and then anneal at 70 ℃ for 1 min to obtain a lead iodide seed layer film. Take 80 μl of MAPbI3 precursor solution and drop it onto the lead iodide seed layer film, spin at 5000 r / min for 30 s, and then drop 400 μl of ethyl acetate at the 8th second to obtain a MAPbI3 film, and then anneal at 70 ℃ for 1 min and at 100 ℃ for 10 min to obtain a high-quality MAPbI3 film.

[0044] (6) Take 40 μl of BAI solution and drop it onto the surface of the MAPbI3 film, spin at 5000 r / min for 30 s, and then anneal at 80 ℃ for 10 min to obtain a two-dimensional / three-dimensional perovskite heterojunction.

[0045] (7) Put a polytetrafluoroethylene heat insulation block 3 and 20 mg of CH3NH3I powder 5 on a hot stage 6 at 130 ℃. Control the temperature on the surface of the polytetrafluoroethylene heat insulation block 3 by adjusting the thickness of the polytetrafluoroethylene heat insulation block 3, so that the temperature on the upper surface of the polytetrafluoroethylene heat insulation block 3 is stabilized at 80 ℃. Then place the prepared two-dimensional / three-dimensional perovskite heterojunction 1 and a small beaker containing isopropanol 2 on the surface of the polytetrafluoroethylene heat insulation block 3. Turn over a glass culture dish 4 to cover all the items on the hot stage, as shown in FIG. 1, to form an atmosphere filled with CH3NH3I / IPA mixed vapor, and maintain for 10 min to obtain a solvent-thermal treated two-dimensional / three-dimensional perovskite heterojunction, denoted as MAI-2D-MAPbI3. Figure 1

[0046] Comparative Example:

[0047] Prepare a three-dimensional lead halide MAPbI3 film using the above steps (1), (2), (3), and (5), denoted as P-MAPbI3, as Comparative Example 1.

[0048] Prepare a two-dimensional / three-dimensional perovskite heterojunction without solvent-thermal treatment using the above steps (1) to (6), denoted as 2D-MAPbI3.

[0049] Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 The surface morphology, X-ray diffraction pattern, steady-state fluorescence (PL) intensity test, current-voltage (I-V) curve test results of the photodetector, and responsivity (R) and detectivity (D*) test results of Example 1, Comparative Example 1, and Comparative Example 2 are shown in FIGS. 2 to 5, respectively.

[0050] ​​​​​The P-MAPbI3 of Comparative Example 1 was prepared by a one-step anti-solvent spin-coating method. Since P-MAPbI3 films prepared by solution methods inevitably contain defects, such as elemental vacancy defects and grain boundary defects, these defects are the main non-radiative recombination centers. These defects cause photogenerated carriers to recombine and dissipate as phonons or heat, thereby reducing the steady-state fluorescence intensity and photoelectric conversion efficiency. The defect passivation effect of Comparative Example 2 and Example 1 compared to Comparative Example 1 was characterized by steady-state fluorescence (PL) intensity testing. Figure 4 As shown. Typically, three-dimensional lead halide perovskite films prepared by solution methods inevitably introduce defects, such as elemental vacancy defects and grain boundary defects. These defects are the main nonradiative recombination centers, causing photogenerated carriers to recombine and dissipate as phonons or heat, thereby reducing the steady-state fluorescence intensity. Comparative Example 2, by preparing a two-dimensional perovskite layer on the surface of a P-MAPbI3 film, utilizes long-chain organic cations to passivate surface defects in the P-MAPbI3 film, reducing nonradiative recombination centers and enhancing the steady-state fluorescence intensity. Example 1, by solvothermal treatment of Comparative Example 2, further improved fluorescence intensity, indicating that Example 1 has better surface defect passivation capabilities.

[0051] However, in Comparative Example 2, the solvent for the two-dimensional perovskite passivation layer prepared by solution method was isopropanol, which has a negative effect on FA. + and MA + Its high solubility leads to the formation of uncoordinated PbI2 byproducts during the preparation of 2D-MAPbI3 films, such as... Figure 3 As shown, this introduces nonradiative recombination centers. Furthermore, the lead iodide byproducts at the interface between the two-dimensional perovskite layer and the three-dimensional lead halide perovskite layer roughen the surface morphology of the 2D-MAPbI3 film, as... Figure 2 In section (b), uneven coverage of the two-dimensional perovskite passivation layer is caused, reducing the passivation effect of the two-dimensional perovskite layer. Because AX / IPA vapor has good permeability, it can convert the lead halide byproducts at the interface between the three-dimensional lead halide perovskite and the two-dimensional perovskite into three-dimensional lead halide perovskite (AX + PbX2 → APbX3) through interpolation reaction, and increase the n value of the two-dimensional perovskite (L′2A). n-1 Pb n X 3n+1 +m(AX)+m(PbX2)→L′2A (m+n)-1 Pb m+n X 3(m+n)+1 In Example 1, the PbI2 byproducts in the MAI-2D-MAPbI3 film treated with AX / IPA vapor disappeared, and the surface morphology became smoother, as shown in the figure. Figure 3 , Figure 2Fig. 3(c) shows that the two-dimensional perovskite passivation layer on the surface of the MAI-2D-MAPbI3 film after AX / IPA vapor treatment can uniformly cover the three-dimensional lead halide surface, realizing effective surface passivation.

[0052] Since the AX / IPA vapor post-treatment eliminates the lead halide byproduct at the interface between the three-dimensional lead halide perovskite and the two-dimensional perovskite and improves the surface morphology, it can effectively reduce the non-radiative recombination centers on the surface of the perovskite film and improve the film quality. This is manifested by a substantial increase in the steady-state fluorescence intensity of the MAI-2D-MAPbI3 film, which is higher than the fluorescence intensity of the two control groups, as shown in Figure 4 .

[0053] Since the smaller the n value of the two-dimensional perovskite is, the stronger the quantum confinement effect in the vertical direction is, which hinders the transport of carriers. Therefore, compared with the P-MAPbI3 film photodetector, the photoelectric current, dark current and responsivity of the 2D-MAPbI3 film photodetector are significantly reduced, as shown in Figure 5 , Figure 6 . With the increase of the n value, the quantum confinement effect is effectively weakened, and the film quality is improved. Compared with the 2D-MAPbI3 film photodetector, the photoelectric current, responsivity and detectivity of the MAI-2D-MAPbI3 film photodetector are significantly improved. Compared with the P-MAPbI3 film photodetector, in addition to the significant increase in photoelectric current, responsivity and detectivity, the dark current is also significantly reduced, as shown in Figure 5 , Figure 6 . Embodiment

[0054] (1) Substrate cleaning and surface treatment: Take 15 mm x 15 mm x 2.2 mm FTO conductive glass; ultrasonic clean the conductive substrate with acetone, anhydrous ethanol and deionized water in turn, remove the oil stains and impurities on the surface of the substrate, and each ultrasonic time is 8 minutes; blow off the water beads on the conductive substrate with nitrogen, and dry in a drying oven at 60 ℃. Ozone cleaning for 10 minutes to increase the hydrophilicity of the substrate surface.

[0055] (2) Preparation of three-dimensional lead halide perovskite precursor solution: Mix methylammonium iodide (MAI) and lead iodide (PbI2) powder ZIF-67 powder according to a molar ratio of 1:1:0.02, and dissolve in a mixed solution of N-N dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) (volume ratio of 6:1) to obtain a MAPbI3 precursor solution with a concentration of 1.5 mol / L.

[0056] (3) Preparation of lead halide seed layer solution: Dissolve PbI2 in a mixed solvent of N-N dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) (volume ratio of 15:1) to form a 1.0 mol / L lead iodide seed layer solution.

[0057] Configuring two-dimensional perovskite cation solution: Weigh a certain amount of butylammonium iodide (BAI) powder and dissolve it into isopropyl alcohol (IPA) to form a BAI solution with a concentration of 10 mg / ml.

[0058] (4) Take 50 μl of lead iodide seed layer solution and drop it onto the FTO substrate, spin at 6000 r / min for 30 s, then anneal at 70 °C for 3 minutes to obtain a lead iodide seed layer film. Take 80 μl of MAPbI3 precursor solution and drop it onto the lead iodide seed layer film, spin at 4500 r / min for 30 s, and drop 350 μl of ethyl acetate at the 10th second to obtain a MAPbI3 film, then anneal at 70 °C for 3 minutes and at 100 °C for 7 minutes to obtain a high-quality MAPbI3 film.

[0059] (5) Take 80 μl of BAI solution and drop it onto the surface of the MAPbI3 film, spin at 4000 r / min for 20 s, then anneal at 100 °C for 10 minutes to obtain a two-dimensional / three-dimensional perovskite heterojunction.

[0060] (6) Put a polytetrafluoroethylene heat insulation block 3 and 40 mg of CH3NH3I powder 5 on a hot stage 6 at 150 °C. Adjust the thickness of the polytetrafluoroethylene heat insulation block 3 to control the temperature on its surface, and stabilize it at 100 °C. Then place the prepared two-dimensional / three-dimensional perovskite heterojunction 1 and a small beaker containing isopropyl alcohol 2 on the surface of the polytetrafluoroethylene heat insulation block 3. Invert a glass culture dish 4 to cover all the items on the hot stage, as shown in Figure 1 , form an atmosphere filled with CH3NH3I / IPA mixed vapor, and maintain for 15 minutes to obtain a solvent thermal treated two-dimensional / three-dimensional perovskite heterojunction, denoted as MAI-2D-MAPbI3.

Claims

1. A method for preparing a solvent-thermally treated two-dimensional / three- dimensional perovskite heterojunction, characterized by, A two-dimensional / three-dimensional perovskite heterojunction is obtained by preparing a two-dimensional perovskite passivation layer on the surface of a three-dimensional lead halide perovskite film, and the two-dimensional / three-dimensional perovskite heterojunction is subjected to a solvothermal treatment: in a closed space, AX powder is placed on a hot stage at 130-180 DEG C, the two-dimensional / three-dimensional perovskite heterojunction and isopropanol (IPA) are placed on a platform at 60-100 DEG C, an atmosphere filled with AX / IPA mixed steam is formed, and the atmosphere is maintained for 5-25 minutes, to obtain a solvothermally treated two-dimensional / three-dimensional perovskite heterojunction; wherein A is a methylamine cation CH3NH3 + (MA + ) or a formamidinium cation H2NCHNH2 + (FA + ), and X is a chlorine anion Cl - , a bromine anion Br - , or an iodine anion I - ; The two-dimensional / three-dimensional perovskite heterojunction comprises a three-dimensional lead halide perovskite thin film APbX3 and a two-dimensional perovskite passivation layer L'2A n-1 Pb n X 3n+1 ; wherein the short chain cation A is a methylamine cation CH3NH3 + (MA + ) or a formamidinium cation H2NCHNH2 + (FA + ), the halide anion X is a chloride anion Cl - , a bromide anion Br - or an iodide anion I - , the long chain organic cation L' is a butylamine cation CH3CH2CH2CH2NH3 + (BA + ) or a phenylethylamine cation C6H5CH2CH2NH3 + (PEA + ), and n is the number of long chain organic cation-wrapped PbX6 octahedra.

2. The method of claim 1, wherein the solvent-thermal treatment is performed at a temperature of 100-200 °C for 1-24 hours. The preparation of the two-dimensional / three-dimensional perovskite heterojunction comprises the following steps: Step 1. Preparation of three-dimensional lead halide perovskite film: Prepare a three-dimensional lead halide perovskite precursor solution, mix AX, PbX2 and ZIF-67 powder in a molar ratio of 1:1:0.01-0.03, dissolve in a mixed solvent of N-N dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) to form a three-dimensional lead halide perovskite precursor solution of 0.6-1.5 mol / L; Prepare a lead halide seed layer solution, dissolve PbX2 in a mixed solvent of N-N dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) to form a lead halide seed layer solution of 0.3-1.3 mol / L; Provide a clean substrate and perform surface treatment; prepare a lead halide seed layer on the substrate by one-step spin coating; anneal at 65-85 ℃ for 1-10 minutes to obtain a lead halide seed layer film; Prepare a three-dimensional lead halide perovskite film on the lead halide seed layer by one-step anti-solvent crystallization; then anneal at 65-85 ℃ for 1-4 minutes and at 90-110 ℃ for 7-15 minutes to dry the solvent, obtaining a three-dimensional lead halide perovskite film; Step 2. Preparation of two-dimensional perovskite passivation layer: Prepare a two-dimensional perovskite cation solution, weigh a certain amount of L'X powder and dissolve it in isopropyl alcohol (IPA) to form a two-dimensional perovskite cation solution with a concentration of 2-20 mg / ml; Spin coat the prepared two-dimensional perovskite cation solution on the surface of the three-dimensional lead halide perovskite and anneal at 70-100 ℃ for 3-10 minutes to obtain a two-dimensional / three-dimensional perovskite heterojunction.

3. The method of claim 2, wherein the solvent-thermal treatment is performed at a temperature of 100-200 °C for 1-24 hours. The volume ratio of the mixed solvent of N-N dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in the perovskite precursor solution of step 1 is 3:1-8:1, and the volume ratio of the mixed solvent of N-N dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in the lead halide seed layer solution is 10:1-19:

1.

4. The method of claim 2, wherein the solvent-thermal treatment is performed at a temperature of 100-200 °C for 1-24 hours. The substrate in step 1 is FTO conductive glass or ITO conductive glass.

5. The method of claim 2, wherein the solvent-thermal treatment is performed at a temperature of 100-200 °C for 1-24 hours. The treatment steps of the substrate in step 1 include: Step A1. Ultrasonic clean the substrate by sequentially placing it in acetone, anhydrous ethanol and deionized water to remove impurities and oil on the surface of the substrate, each ultrasonic time is 4-9 minutes; Step A2. Blow off the residual water droplets on the surface of the conductive glass substrate with nitrogen; Step A3. Dry the substrate in a drying oven at 50-70 ℃; Step A4. Plasma clean for 2-4 minutes or ultraviolet ozone clean for 5-15 minutes to increase the hydrophilicity of the substrate surface.

6. The preparation method of the solvent-thermal treated two-dimensional / three-dimensional perovskite heterojunction according to claim 2, characterized in that In step 1, the anti-solvent used in the anti-solvent crystallization method is one or two of toluene, ethyl acetate and chlorobenzene.

7. The method of claim 1, wherein the solvent-thermal treatment is performed at a temperature of 100-200 °C for 1-24 hours. The solvent thermal treatment process is to construct a closed space by inverting a glass container on a hot stage at 130-180 DEG C, and to construct a platform at 60-100 DEG C by using a polytetrafluoroethylene heat insulation block placed on the hot stage, and the two-dimensional / three-dimensional perovskite heterojunction, isopropyl alcohol (IPA) is placed on the polytetrafluoroethylene heat insulation block.

8. The two-dimensional / three-dimensional perovskite heterojunction prepared by the preparation method in any one of claims 1-7.

9. Use of the two-dimensional / three-dimensional perovskite heterojunction according to claim 8, characterized in that, For a photoelectric detection device or a photoelectric conversion device.

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