Two-dimensional / three-dimensional perovskite heterojunction subjected to solvent heat treatment, preparation method and application

Abstract

The invention provides a two-dimensional / three-dimensional perovskite heterojunction subjected to solvent heat treatment, a preparation method and application. After the two-dimensional perovskite passivation layer is prepared on the surface of the three-dimensional lead halide perovskite thin film, solvent heat treatment is carried out through AX / IPA mixed steam, lead halide by-products at a two-dimensional / three-dimensional perovskite heterojunction interface are eliminated, and the number of halide octahedron layers in two-dimensional perovskite is increased. According to the invention, the non-radiation load center on the surface of the film is effectively reduced, the passivation effect of the two-dimensional perovskite is enhanced, and the photoelectric conversion efficiency is improved; moreover, the out-of-plane transmission capability of carriers is enhanced, the conductivity in the vertical direction is improved, the current loss is reduced, and the responsivity and the detection rate of the device are improved. The problem of solvent incompatibility in two-dimensional / three-dimensional perovskite heterojunction prepared by a traditional solution method is solved, effective passivation of surface defects of the perovskite thin film is realized, and powerful technical support is provided for preparation of high-performance stable perovskite thin film photoelectric devices.

Description

Technical Field

[0001] The present invention relates to the technical field of optoelectronic devices, and in particular to a solvent-thermally treated two-dimensional / three-dimensional perovskite heterojunction, a preparation method and an application thereof. Background Art

[0002] In recent years, three-dimensional lead halide 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, and long carrier lifetime, and are considered to be important semiconductor materials for the preparation of high-performance optoelectronic devices. However, a large number of surface defects lead to serious non-radiative recombination losses, which greatly reduce the optoelectronic performance and stability of the device. Passivating the surface defects of three-dimensional lead halide perovskite films with two-dimensional perovskites is very important for the manufacture of high-performance optoelectronic devices. However, solvent incompatibility usually leads to the formation of lead halide byproducts in the prepared two-dimensional / three-dimensional perovskite heterojunctions, thereby preventing the two-dimensional perovskite from exerting its passivation potential. Therefore, repairing the lead halide byproducts in the two-dimensional / three-dimensional perovskite heterojunctions and suppressing the defect states are crucial for the preparation of high-performance and stable optoelectronic devices. Summary of the invention

[0003] In view of some deficiencies in the prior art, the present invention provides a two-dimensional / three-dimensional perovskite heterojunction treated with solvents, a preparation method and an application. The present invention not only effectively reduces the non-radiative load center on the surface of the film, enhances the passivation effect of the two-dimensional perovskite, and improves the photoelectric conversion efficiency through solvent thermal treatment; but also enhances the out-of-plane transmission capacity of carriers, improves the conductivity in the vertical direction, reduces current loss, and improves the responsiveness and detection rate 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 the effective passivation of the surface defects of the perovskite film.

[0004] The invention provides a method for preparing a two-dimensional / three-dimensional perovskite heterojunction by solvent thermal treatment, wherein a two-dimensional perovskite passivation layer is prepared on the surface of a three-dimensional lead halide perovskite 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 platform at 130-180° C., the two-dimensional / three-dimensional perovskite heterojunction and isopropyl alcohol (IPA) are placed on a platform at 60-100° C., an atmosphere filled with AX / IPA mixed vapor is formed, and the atmosphere is maintained for 5-25 minutes, so as to obtain a two-dimensional / three-dimensional perovskite heterojunction subjected to solvent thermal treatment; wherein A is a methylamine cation CH3NH3 + (MA + ) or formamidinium cation H2NCHNH2 + (FA + ), X is a chloride anion Cl - , bromide anion Br- or iodide anion I - .

[0005] Furthermore, the two-dimensional / three-dimensional perovskite heterojunction includes 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 halogen anion X is a chloride anion Cl - , bromide anion Br - or iodide anion I - , the long-chain organic cation L' is a butylamine cation CH3CH2CH2CH2NH3 + (BA + ) or phenylethylamine cation C6H5CH2CH2NH3 + (PEA + ), n is the number of PbX6 octahedrons wrapped by long-chain organic cations.

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

[0007] Step 1. Preparation of three-dimensional lead halide perovskite thin films:

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

[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 0.3-1.3 mol / L lead halide seed layer solution;

[0010] Providing a clean substrate and performing surface treatment; preparing a lead halide seed layer on the substrate by a one-step spin coating method; annealing at 65 to 85° C. for 1 to 10 minutes to obtain a lead halide seed layer film;

[0011] A three-dimensional lead halide perovskite film is prepared on the lead halide seed layer by a one-step anti-solvent crystallization method; annealing at 65-85° C. for 1-4 minutes, annealing at 90-110° C. for 7-15 minutes, and drying the solvent to obtain a three-dimensional lead halide perovskite film;

[0012] Step 2. Preparation of 2D perovskite passivation layer:

[0013] A two-dimensional perovskite cation solution is prepared by weighing a certain amount of L′X powder and dissolving it into isopropyl alcohol (IPA) to form a two-dimensional perovskite cation solution with a concentration of 2 to 20 mg / ml;

[0014] The configured two-dimensional perovskite cation solution is spin-coated on the surface of the three-dimensional lead halide perovskite and annealed at 70-100°C for 3-10 minutes to obtain a two-dimensional / three-dimensional perovskite heterojunction.

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

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

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

[0018] Step A1. Place the substrate in acetone, anhydrous ethanol and deionized water in turn to perform ultrasonic cleaning on the substrate to remove impurities and oil stains on the surface of the substrate. Each ultrasonic cleaning time is 4 to 9 minutes.

[0019] Step A2. Blowing 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 cleaning for 2 to 4 minutes, or ultraviolet ozone cleaning for 5 to 15 minutes, to increase the surface hydrophilicity of the substrate.

[0022] Furthermore, in step 1, the antisolvent used in the antisolvent crystallization method is one or two of toluene, ethyl acetate, and chlorobenzene.

[0023] Furthermore, the solvent thermal treatment process is to construct a closed space by placing a glass vessel upside down on a hot stage at 130-180°C, and to construct a platform controlled at 60-100°C by using a polytetrafluoroethylene insulation block placed on the hot stage, and the two-dimensional / three-dimensional perovskite heterojunction and isopropyl alcohol (IPA) are placed on the polytetrafluoroethylene insulation block.

[0024] A 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 that it is used in photoelectric detection devices or photoelectric conversion devices.

[0026] The beneficial effects of the present invention are:

[0027] Because the lead halide film prepared by the solution method has a large number of element vacancy defects and grain boundary defects, such as element vacancy defects and grain boundary defects. These defects are the main non-radiative recombination centers, which will cause the photogenerated carriers to recombine and dissipate in the form of phonons or heat, thereby reducing the luminous intensity of the fluorescence and the photoelectric conversion efficiency. The present invention first prepares a two-dimensional perovskite passivation layer on the surface of the three-dimensional lead halide perovskite film, and uses long-chain organic cations to passivate the surface defect states of the three-dimensional lead halide perovskite film. Subsequently, AX / IPA vapor is used for solvent thermal treatment. Taking advantage of the permeability of AX / IPA vapor and the soft lattice characteristics of the perovskite film, AX / IPA vapor can penetrate into the interior of the two-dimensional / three-dimensional perovskite heterojunction and undergo an intercalation reaction with the lead halide by-products at the interface of the two-dimensional / three-dimensional perovskite heterojunction, namely: AX+PbX2→APbX3, thereby converting the lead halide by-products into APbX3, effectively reducing the non-radiative recombination centers on the surface of the film, enhancing the passivation effect of the two-dimensional perovskite, improving the photoelectric conversion efficiency of the material, and improving the sensitivity and weak light detection capability of the photodetector.

[0028] At the same time, the number of PbX6 octahedral layers in the two-dimensional perovskite, i.e., the n value, increases due to the interpolation 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 , also increases to become m+n; the quantum confinement effect in the vertical direction is weakened, resulting in an enhanced out-of-plane transmission capability of the carriers, an increase in the vertical conductivity, a reduction in current loss, and an increase in the device's responsiveness and detection rate.

[0029] The present invention solves the problem of solvent incompatibility in two-dimensional / three-dimensional perovskite heterojunctions prepared by traditional solution methods, achieves effective passivation of surface defects of perovskite films, and provides strong technical support for the preparation of high-performance and stable perovskite thin film optoelectronic devices, such as solar cells, photodetectors and light-emitting diodes, and has important application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the solvothermal treatment of 2D / 3D perovskite heterojunctions.

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

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

[0033] Figure 4 This is a graph showing the steady-state fluorescence (PL) intensity test results of the perovskite film.

[0034] Figure 5 This is a graph showing the current-voltage (IV) curve test results of the perovskite thin film photodetector.

[0035] Figure 6 This is a graph showing the test results of the responsivity (R) and detectivity (D*) 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 insulation block, 4 is a glass culture dish, 5 is CH3NH3I powder, and 6 is a hot stage. DETAILED DESCRIPTION

[0038] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

[0039] Embodiment 1:

[0040] (1) Substrate cleaning and surface treatment: Take 15 mm × 15 mm × 1.1 mm ITO conductive glass; use acetone, anhydrous ethanol and deionized water to ultrasonically clean the conductive substrate in turn to remove oil and impurities on the substrate surface. Each ultrasonic cleaning lasts for 5 minutes. Blow off the water droplets on the conductive substrate with nitrogen and dry it in a drying oven at 50°C. Then use plasma cleaning for 200 seconds to increase the hydrophilicity of the substrate surface.

[0041] (2) Preparation of three-dimensional lead halide perovskite precursor solution: Methyl ammonium iodide (MAI), lead iodide (PbI2) powder, and ZIF-67 powder were mixed in 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 1.3 mol / L MAPbI3 precursor solution.

[0042] (3) Preparing a lead halide seed layer solution: PbI2 was 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.

[0043] (4) Preparing a two-dimensional perovskite cation solution: Weigh a certain amount of butylamine iodide (BAI) powder and dissolve it in isopropyl alcohol (IPA) to form a BAI solution with a concentration of 5 mg / ml.

[0044] (5) Take 40 μl of lead iodide seed layer solution and drop it on the ITO substrate, spin-coat it at 5000 r / min for 30 seconds, and then anneal it at 70°C for 1 minute to obtain a lead iodide seed layer film. Take 80 μl of MAPbI3 precursor solution and drop it on the lead iodide seed layer film, spin-coat it at 5000 r / min for 30 seconds, and then add 400 μl of ethyl acetate at the 8th second to obtain a MAPbI3 film, and then anneal it at 70°C for 1 minute and 100°C for 10 minutes to obtain a high-quality MAPbI3 film.

[0045] (6) Take 40 μl of BAI solution and drop it onto the surface of MAPbI3 film, spin coat it at 5000 r / min for 30 s, and then anneal it at 80 °C for 10 min to obtain a two-dimensional / three-dimensional perovskite heterojunction.

[0046] (7) Place a polytetrafluoroethylene insulation block 3 and 20 mg of CH3NH3I powder 5 on a 130°C hot plate 6. The surface temperature of the polytetrafluoroethylene insulation block 3 is controlled by adjusting the thickness of the polytetrafluoroethylene insulation block 3, so that the temperature of the upper surface of the polytetrafluoroethylene insulation block 3 is stabilized at 80°C. Then, place the prepared two-dimensional / three-dimensional perovskite heterojunction 1 and a small beaker containing isopropanol 2 on the surface of the polytetrafluoroethylene insulation block 3. Place an inverted glass culture dish 4 to cover all items on the hot plate, such as Figure 1 As shown, an atmosphere filled with CH3NH3I / IPA mixed vapor was formed and maintained for 10 minutes to obtain a solvothermally treated two-dimensional / three-dimensional perovskite heterojunction, which was recorded as MAI-2D-MAPbI3.

[0047] Comparison example:

[0048] The three-dimensional lead halide MAPbI3 thin film was prepared by using the above steps (1), (2), (3) and (5), and was denoted as P-MAPbI3, as control example 1.

[0049] The above steps (1) to (6) are used to prepare a two-dimensional / three-dimensional perovskite heterojunction without solvent thermal treatment, which is denoted as 2D-MAPbI3.

[0050] Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 They are the surface morphology, X-ray diffraction pattern, steady-state fluorescence (PL) intensity test, current-voltage (IV) curve test result graph of the photodetector, and the test results of the responsivity (R) and detectivity (D*) of the photodetector of Example 1, Control Example 1, and Control Example 2, respectively.

[0051] The P-MAPbI3 of Control Example 1 was prepared by a one-step anti-solvent spin coating method. Since the P-MAPbI3 film prepared by the solution method inevitably produces defects, such as element vacancy defects, grain boundary defects, etc. These defects are the main non-radiative recombination centers, which will cause the photogenerated carriers to recombine and dissipate in the form of phonons or heat, thereby reducing the luminous intensity of steady-state fluorescence and the photoelectric conversion efficiency. The steady-state fluorescence (PL) intensity test was used to characterize the defect passivation effect of Control Example 2 and Example 1 compared with Control Example 1, as shown in FIG. Figure 4 As shown. Usually, three-dimensional lead halide perovskite films prepared by solution method will inevitably produce defects, such as element vacancy defects, grain boundary defects, etc. These defects are the main non-radiative recombination centers, which will cause the photogenerated carriers to recombine and dissipate in the form of phonons or heat, thereby reducing the luminescence intensity of steady-state fluorescence. Control Example 2 prepares a layer of two-dimensional perovskite on the surface of the P-MAPbI3 film, and its long-chain organic cations can passivate the surface defects of the P-MAPbI3 film, reduce non-radiative recombination centers, and enhance the luminescence intensity of steady-state fluorescence. In Example 1, by performing solvent thermal treatment on Control Example 2, the fluorescence intensity is further improved, indicating that Example 1 has better surface defect passivation ability.

[0052] However, in Comparative Example 2, the solvent of the two-dimensional perovskite passivation layer prepared by the solution method is isopropanol, which has a great influence on the FA + and MA + The high solubility leads to the generation of uncoordinated PbI2 byproducts during the preparation of 2D-MAPbI3 films, such as Figure 3 As shown, non-radiative recombination centers are introduced. In addition, the lead iodide byproducts at the interface between the two-dimensional perovskite layer and the three-dimensional lead halide perovskite make the surface morphology of the 2D-MAPbI3 film rough, as shown in Figure 2 (b), resulting in uneven coverage of the two-dimensional perovskite passivation layer, reducing the passivation effect of the two-dimensional perovskite layer. Due to the good permeability of AX / IPA vapor, the lead halide byproducts at the interface between the three-dimensional lead halide perovskite and the two-dimensional perovskite can be converted into three-dimensional lead halide perovskite (AX+PbX2→APbX3) through intercalation reaction, and 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)- 1Pb m+n X 3(m+n)+1 ). After the MAI-2D-MAPbI3 film was treated with AX / IPA steam in Example 1, the PbI2 byproduct disappeared and the surface morphology became smooth, as shown in FIG. Figure 3 , Figure 2(c) shows that the two-dimensional perovskite passivation layer on the surface of the MAI-2D-MAPbI3 film after AX / IPA vapor treatment can evenly cover the three-dimensional lead halide surface to achieve effective surface passivation.

[0053] Since the AX / IPA vapor post-treatment eliminates the lead halide byproducts 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 in a significant increase in the steady-state fluorescence intensity of the MAI-2D-MAPbI3 film, which is higher than the fluorescence intensity of the two control examples, such as Figure 4 .

[0054] Since the smaller the n value of the two-dimensional perovskite, the stronger the quantum confinement effect in the vertical direction, which will hinder the transmission of carriers. Therefore, compared with the P-MAPbI3 thin film photodetector, the photocurrent, dark current and responsivity of the 2D-MAPbI3 thin film photodetector are significantly reduced, such as Figure 5 , Figure 6 . As the n value increases, the quantum confinement effect is effectively weakened, and the film quality improves. Compared with the 2D-MAPbI3 thin film photodetector, the photocurrent, responsivity and detection rate of the MAI-2D-MAPbI3 thin film photodetector are significantly improved. Compared with the P-MAPbI3 thin film photodetector, in addition to the significant improvement in photocurrent, responsivity and detection rate, the dark current is also significantly reduced, such as Figure 5 , Figure 6 .

[0055] Embodiment 2:

[0056] (1) Substrate cleaning and surface treatment: Take a 15 mm × 15 mm × 2.2 mm FTO conductive glass; use acetone, anhydrous ethanol and deionized water to ultrasonically clean the conductive substrate in turn to remove oil and impurities on the substrate surface. Each ultrasonic cleaning time is 8 minutes; blow off the water droplets on the conductive substrate with nitrogen, and dry it in a drying oven at 60°C. Ozone cleaning for 10 minutes to increase the hydrophilicity of the substrate surface.

[0057] (2) Prepare a three-dimensional lead halide perovskite precursor solution: Mix methyl ammonium iodide (MAI) and lead iodide (PbI2) powder ZIF-67 powder in a molar ratio of 1:1:0.02, dissolve in a mixed solution of N-N dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) (volume ratio of 6:1) to obtain a 1.5 mol / L MAPbI3 precursor solution.

[0058] (3) Preparing a lead halide seed layer solution: PbI2 was dissolved 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.

[0059] Prepare a two-dimensional perovskite cation solution: weigh a certain amount of butylamine iodide (BAI) powder and dissolve it in isopropyl alcohol (IPA) to form a BAI solution with a concentration of 10 mg / ml.

[0060] (4) Take 50 μl of lead iodide seed layer solution and drop it on the FTO substrate, spin-coat it at 6000 r / min for 30 seconds, and then anneal it at 70°C for 3 minutes to obtain a lead iodide seed layer film. Take 80 μl of MAPbI3 precursor solution and drop it on the lead iodide seed layer film, spin-coat it at 4500 r / min for 30 seconds, and then add 350 μl of ethyl acetate at the 10th second to obtain a MAPbI3 film, and then anneal it at 70°C for 3 minutes and 100°C for 7 minutes to obtain a high-quality MAPbI3 film.

[0061] (5) Take 80 μl of BAI solution and drop it onto the surface of MAPbI3 film, spin coat it at 4000 r / min for 20 s, and then anneal it at 100 °C for 10 min to obtain a two-dimensional / three-dimensional perovskite heterojunction.

[0062] (6) Place a polytetrafluoroethylene insulation block 3 and 40 mg of CH3NH3I powder 5 on a 150°C hot plate 6. The surface temperature of the polytetrafluoroethylene insulation block 3 is controlled by adjusting the thickness of the polytetrafluoroethylene insulation block 3 to stabilize it at 100°C. Then place the prepared two-dimensional / three-dimensional perovskite heterojunction 1 and a small beaker containing isopropanol 2 on the surface of the polytetrafluoroethylene insulation block 3. Place an inverted glass petri dish 4 to cover all items on the hot plate, such as Figure 1 As shown, an atmosphere filled with CH3NH3I / IPA mixed vapor was formed and maintained for 15 minutes to obtain a solvothermally treated two-dimensional / three-dimensional perovskite heterojunction, which was recorded as MAI-2D-MAPbI3.

Claims

1. A method for preparing a two-dimensional / three-dimensional perovskite heterojunction by solvent thermal treatment, characterized in that: A two-dimensional perovskite passivation layer is prepared on the surface of a three-dimensional lead halide perovskite film to obtain a two-dimensional / three-dimensional perovskite heterojunction, and the two-dimensional / three-dimensional perovskite heterojunction is subjected to a solvent thermal treatment: in a closed space, AX powder is placed on a hot plate at 130-180° C., and the two-dimensional / three-dimensional perovskite heterojunction and isopropyl alcohol (IPA) are placed on a platform at 60-100° C. to form an atmosphere filled with AX / IPA mixed vapor, and the atmosphere is maintained for 5-25 minutes to obtain a solvent thermally treated two-dimensional / three-dimensional perovskite heterojunction; wherein A is a methylamine cation CH3NH3 + (MA + ) or formamidinium cation H2NCHNH2 + (FA + ), X is a chloride anion Cl - , bromide anion Br - or iodide anion I - .

2. The method for preparing a two-dimensional / three-dimensional perovskite heterojunction by solvent thermal treatment according to claim 1, characterized in that: The two-dimensional / three-dimensional perovskite heterojunction includes 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 halogen anion X is a chloride anion Cl - , bromide anion Br - or iodide anion I - , the long-chain organic cation L' is a butylamine cation CH3CH2CH2CH2NH3 + (BA + ) or phenylethylamine cation C6H5CH2CH2NH3 + (PEA + ), n is the number of PbX6 octahedrons wrapped by long-chain organic cations.

3. The method for preparing a two-dimensional / three-dimensional perovskite heterojunction by solvent thermal treatment according to claim 2, characterized in that: The preparation of the two-dimensional / three-dimensional perovskite heterojunction comprises the following steps: Step 1. Preparation of three-dimensional lead halide perovskite thin films: A three-dimensional lead halide perovskite precursor solution is prepared, AX, PbX2, and ZIF-67 powders are mixed in a molar ratio of 1:1:0.01-0.03, and dissolved in a mixed solvent of N-N dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) to form a 0.6-1.5 mol / L three-dimensional lead halide perovskite precursor solution; 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 0.3-1.3 mol / L lead halide seed layer solution; Providing a clean substrate and performing surface treatment; preparing a lead halide seed layer on the substrate by a one-step spin coating method; annealing at 65 to 85° C. for 1 to 10 minutes to obtain a lead halide seed layer film; A three-dimensional lead halide perovskite film is prepared on the lead halide seed layer by a one-step anti-solvent crystallization method; annealing at 65-85° C. for 1-4 minutes, annealing at 90-110° C. for 7-15 minutes, and drying the solvent to obtain a three-dimensional lead halide perovskite film; Step 2. Preparation of 2D perovskite passivation layer: A two-dimensional perovskite cation solution is prepared by weighing a certain amount of L′X powder and dissolving it into isopropyl alcohol (IPA) to form a two-dimensional perovskite cation solution with a concentration of 2 to 20 mg / ml; The configured two-dimensional perovskite cation solution is spin-coated on the surface of the three-dimensional lead halide perovskite and annealed at 70-100°C for 3-10 minutes to obtain a two-dimensional / three-dimensional perovskite heterojunction.

4. The method for preparing a two-dimensional / three-dimensional perovskite heterojunction by solvent thermal treatment according to claim 3, characterized in that: The volume ratio of the mixed solvent of NNN dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in the perovskite precursor solution of step 1 is 3:1 to 8:1, and the volume ratio of the mixed solvent of NNN dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in the lead halide seed layer solution is 10:1 to 19:

1.

5. The method for preparing a two-dimensional / three-dimensional perovskite heterojunction by solvent thermal treatment according to claim 3, characterized in that: The substrate described in step 1 is FTO conductive glass or ITO conductive glass.

6. The method for preparing a two-dimensional / three-dimensional perovskite heterojunction by solvent thermal treatment according to claim 3, characterized in that: The processing steps of the substrate in step 1 include: Step A1. Place the substrate in acetone, anhydrous ethanol and deionized water in turn to perform ultrasonic cleaning on the substrate to remove impurities and oil stains on the surface of the substrate. Each ultrasonic cleaning time is 4 to 9 minutes. Step A2. Blowing 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°C; Step A4: Plasma cleaning for 2 to 4 minutes, or ultraviolet ozone cleaning for 5 to 15 minutes, to increase the surface hydrophilicity of the substrate.

7. The method for preparing a two-dimensional / three-dimensional perovskite heterojunction by solvent thermal treatment according to claim 3, characterized in that: In step 1, the antisolvent used in the antisolvent crystallization method is one or two of toluene, ethyl acetate and chlorobenzene.

8. The method for preparing a two-dimensional / three-dimensional perovskite heterojunction by solvent thermal treatment according to claim 1, characterized in that: The solvent thermal treatment process is to use a glass vessel inverted on a hot stage at 130-180°C to construct a closed space, and use a polytetrafluoroethylene insulation block placed on the hot stage to construct a platform controlled at 60-100°C, and the two-dimensional / three-dimensional perovskite heterojunction and isopropyl alcohol (IPA) are placed on the polytetrafluoroethylene insulation block.

9. A two-dimensional / three-dimensional perovskite heterojunction prepared by the preparation method according to any one of claims 1 to 8.

10. The use of the two-dimensional / three-dimensional perovskite heterojunction according to claim 9, characterized in that: Used in photoelectric detection devices or photoelectric conversion devices.

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