An electron transport layer, a preparation method therefor and use thereof

Abstract

The application belongs to the technical field of perovskite solar cells, and provides an electron transport layer, which comprises a substrate, a metal Ti seed layer arranged on the surface of the substrate, and a titanium dioxide nanosheet array arranged on the surface of the metal Ti seed layer. The application also provides a perovskite solar cell with a color electron transport layer prepared by one-step method, and the titanium dioxide nanosheet array is grown in situ on the surface of the conductive substrate. The micro-nano structure with a subwavelength size scatters and diffracts light, so that the micro-nano structure displays structural color. The electron transport layer provided by the application can be used to prepare a color perovskite solar cell.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of perovskite solar cells, and particularly relates to an electron transport layer and a preparation method and application thereof. BACKGROUND

[0002] Color perovskite solar cells can meet the aesthetic demand of the market for photovoltaic modules and have potential application value in the field of building photovoltaic integration. At present, the colorization technology of color perovskite cells mainly includes three types, the first type is to directly coat a layer of pigment on the surface of the cover glass; the second type is to regulate the band gap of the perovskite layer; and the third type is the colorization technology based on structural color, which has the characteristics of not easy to fade and high contrast, and therefore is widely concerned. Structural color is to reflect specific bands of visible light by preparing nanostructures with special morphology, such as nanospheres and nanocavities, which usually adopts a sacrificial template method or a photolithography method, and the preparation steps are complicated, the cost is high and it is not conducive to large-area preparation. SUMMARY

[0003] Therefore, the purpose of the present application is to provide an electron transport layer and a preparation method and application thereof, the electron transport layer provided by the present application grows titanium dioxide nanosheet arrays in situ on the surface of a substrate, and is used to obtain color perovskite cells.

[0004] The present application provides an electron transport layer, comprising:

[0005] a substrate;

[0006] a metal Ti seed layer arranged on the surface of the substrate;

[0007] a titanium dioxide nanosheet array arranged on the surface of the metal Ti seed layer.

[0008] Preferably, the thickness of the metal Ti seed layer is 5-20 nm.

[0009] Preferably, the thickness of the titanium dioxide nanosheet in the titanium dioxide nanosheet array is 5-50 nm, and the length of the titanium dioxide nanosheet is 50 nm-2 μm.

[0010] Preferably, the total thickness of the metal Ti seed layer and the titanium dioxide nanosheet array is 200-500 nm.

[0011] The present application provides a preparation method of the electron transport layer described in the above technical solution, comprising:

[0012] preparing a metal Ti seed layer on the surface of a substrate;

[0013] adopting a chemical vapor deposition method to prepare a titanium dioxide nanosheet array on the surface of the metal Ti seed layer.

[0014] Preferably, the method for preparing the metal Ti seed layer is selected from thermal evaporation, magnetron sputtering or atomic layer deposition.

[0015] Preferably, the Ti source in the chemical deposition method is placed in a low-temperature zone, and the substrate is placed in a high-temperature zone, the low-temperature zone is connected by a quartz tube, and N2 / O2 mixed gas is introduced.

[0016] Preferably, the titanium source is selected from one or more of titanium acetylacetonate, titanium tert-butoxide, methyl titanate and isopropyl titanate.

[0017] Preferably, the temperature of the low-temperature zone is 100-300°C, the temperature of the high-temperature zone is 400-800°C, and the volume content of O2 in the N2 / O2 mixed gas is 1-5%.

[0018] The present application provides a perovskite battery, comprising:

[0019] The electronic transport layer in the technical solution described above;

[0020] The perovskite layer arranged on the surface of the titanium dioxide nanosheet array of the electronic transport layer;

[0021] The hole transport layer arranged on the surface of the perovskite layer;

[0022] The electrode arranged on the surface of the hole transport layer.

[0023] The present application provides a perovskite solar cell with a color electronic transport layer prepared by one-step method, in which a titanium dioxide nanosheet array is grown in situ on the surface of a conductive substrate. The subwavelength micro-nano structure of such size scatters and diffracts light, thereby showing structural color. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The figure is a schematic diagram of the preparation of a titanium dioxide nanosheet array by a gas phase deposition method in the embodiments of the present application;

[0025] Figure 2 The figure is a structural schematic diagram of an electronic transport layer provided in the embodiments of the present application;

[0026] Figure 3 The figure is a structural schematic diagram of a perovskite battery provided in the embodiments of the present application. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0028] The application provides an electron transport layer, comprising:

[0029] a substrate;

[0030] a metal Ti seed layer arranged on the surface of the substrate;

[0031] a titanium dioxide nanosheet array arranged on the surface of the metal Ti seed layer.

[0032] In the application, the substrate is preferably selected from a transparent conductive substrate such as FTO, ITO, AZO and the like.

[0033] In the application, the thickness of the metal Ti seed layer is preferably 5-20 nm, more preferably 10-15 nm, and most preferably 10 nm.

[0034] In the application, the thickness of the titanium dioxide nanosheet array is preferably 150-250 nm, more preferably 180-220 nm, and most preferably 200 nm.

[0035] In the application, the thickness of the titanium dioxide nanosheet in the titanium dioxide nanosheet array is preferably 5-50 nm, more preferably 10-40 nm, and most preferably 20-30 nm; the length of the titanium dioxide nanosheet is preferably 50 nm-2 μm, more preferably 100 nm-1.5 μm, more preferably 500-1000 nm, and most preferably 600-800 nm.

[0036] In the application, the total thickness of the metal Ti seed layer and the titanium dioxide nanosheet array is preferably 200-500 nm, more preferably 200-400 nm, more preferably 200-300 nm, and most preferably 200 nm.

[0037] The application provides a preparation method of the electron transport layer as described in the above technical solution, comprising:

[0038] preparing a metal Ti seed layer on the surface of a substrate;

[0039] adopting a chemical vapor deposition method to prepare a titanium dioxide nanosheet array on the surface of the metal Ti seed layer.

[0040] In the application, the preparation of the seed layer preferably further comprises, before the preparation of the seed layer:

[0041] cleaning the substrate.

[0042] In the present application, the cleaning preferably adopts ultrasonic cleaning; preferably, deionized water, acetone and ethanol are used for ultrasonic cleaning in the ultrasonic cleaning process, and the time for the ultrasonic cleaning is preferably 15-25 min, more preferably 20 min; preferably, the ultrasonic cleaning is followed by nitrogen blowing for drying.

[0043] In the present application, the method for preparing the seed layer preferably comprises:

[0044] Depositing metal Ti on the surface of the substrate.

[0045] In the present application, the deposition method is preferably selected from thermal evaporation, magnetron sputtering or atomic layer deposition, more preferably thermal evaporation; the cavity vacuum degree in the thermal evaporation process is preferably 4.0E -4 Pa-1.0E -3 Pa, more preferably 4.0E -4 Pa; the cavity temperature is preferably 100-300℃, more preferably 150-250℃, most preferably 200℃; the evaporation rate is preferably more preferably

[0046] In the present application, the Ti source in the chemical vapor deposition process is preferably selected from Ti metal organic compounds such as titanium acetylacetonate, titanium tert-butoxide, methyl titanate and isopropyl titanate.

[0047] In the present application, the Ti source in the chemical deposition process is placed in a low-temperature zone, and the substrate is located in a high-temperature zone, the low-temperature zone is linked by a quartz tube, and N2 / O2 mixed gas is introduced, as shown in Figure 1 .

[0048] In the present application, the temperature of the low-temperature zone is preferably 100-300℃, more preferably 150-250℃, most preferably 200℃; the temperature of the high-temperature zone is preferably 400-800℃, more preferably 500-700℃, most preferably 600℃; the volume content of O2 in the N2 / O2 mixed gas is preferably 1-5%, more preferably 2-4%, most preferably 3%; the time for the chemical deposition is preferably 0.5-1.5h, more preferably 1h.

[0049] The present application provides a perovskite battery, comprising:

[0050] The electron transport layer in the above technical solution;

[0051] The perovskite layer arranged on the surface of the titanium dioxide nanosheet array of the electron transport layer;

[0052] The hole transport layer arranged on the surface of the perovskite layer;

[0053] An electrode disposed on a surface of the hole transport layer.

[0054] In the present application, the composition of the perovskite layer is preferably selected from organic-inorganic hybrid lead halide perovskite, organic-inorganic hybrid tin / lead mixed halide perovskite, and all-inorganic perovskite, and the like light-absorbing materials having perovskite crystal form; more preferably, it includes PbI2 and FAI; the mass ratio of the PbI2 and FAI is preferably (3-4):(1-1.5), more preferably (3.6-3.8):(1.3-1.5), and most preferably 3.688:1.376.

[0055] In the present application, the thickness of the perovskite layer is preferably 300-1500 nm, more preferably 400-1200 nm, more preferably 400-800 nm, more preferably 400-600 nm, and most preferably 400 nm.

[0056] In the present application, the composition of the hole transport layer is preferably selected from spiro-OMeTAD, P3HT, PTAA, and the like, and more preferably spiro-OMeTAD.

[0057] In the present application, the thickness of the hole transport layer is preferably 20-200 nm, more preferably 50-150 nm, more preferably 50-100 nm, more preferably 50-80 nm, and most preferably 50 nm.

[0058] In the present application, the composition of the electrode is preferably selected from metal materials such as gold, silver, and copper, and carbon materials such as graphene and amorphous carbon.

[0059] In the present application, the thickness of the electrode is preferably 20 nm-50 μm, more preferably 50 nm-40 μm, more preferably 100 nm-30 μm, more preferably 150 nm-20 μm, and most preferably 200 nm.

[0060] In the embodiment of the present application, the structure diagram of the perovskite battery is as shown in Figure 3 which includes a top electrode 1, a hole transport layer 2, a perovskite layer 3, an electron transport layer 4, and a transparent conductive glass substrate 5; the structure of the electron transport layer is as shown in Figure 2 which includes a transparent conductive glass substrate 5, a metal Ti seed layer 6, and a titanium dioxide nanosheet array 7.

[0061] In the present application, the preparation method of the perovskite battery preferably includes:

[0062] Preparation of a perovskite layer on a surface of the titanium dioxide nanosheet array of the electron transport layer;

[0063] Preparation of a hole transport layer on a surface of the perovskite layer;

[0064] An electrode is prepared on the surface of the hole transport layer.

[0065] In the present application, the preparation method of the electron transport layer is consistent with the above technical solution, which will not be described here.

[0066] In the present application, the preparation method of the perovskite layer preferably comprises:

[0067] A perovskite material is deposited on the surface of the electron transport layer.

[0068] In the present application, the perovskite material is preferably selected from organic-inorganic hybrid lead halide perovskite, organic-inorganic hybrid tin / lead mixed halide perovskite, and all-inorganic perovskite, etc. light-absorbing materials with perovskite crystal form, more preferably comprising PbI2 and FAI; the mass ratio of the PbI2 and FAI is preferably (3-4):(1-1.5), more preferably (3.6-3.8):(1.3-1.5), and most preferably 3.688:1.376.

[0069] In the present application, the perovskite material is preferably a perovskite material solution, and the mass concentration of the perovskite material solution is preferably 20-40%, more preferably 25-35%, and most preferably 30%; the solvent in the perovskite solution is preferably NMP.

[0070] In the present application, the deposition method includes but is not limited to spin coating, blade coating, spraying, slot coating, screen printing, evaporation, CVD, etc., and the preferred method is blade coating; the blade coating speed is preferably 10-15 mm / s, more preferably 12-13 mm / s.

[0071] In the present application, after deposition, preferably further comprising annealing.

[0072] In the present application, the annealing temperature is preferably 130-170℃, more preferably 140-160℃, and most preferably 150℃; the annealing time is preferably 10-30 minutes, more preferably 15-25 minutes, and most preferably 20 minutes.

[0073] In the present application, the preparation method of the hole transport layer preferably comprises:

[0074] A hole transport layer material is deposited on the surface of the perovskite layer.

[0075] In the present application, the hole transport layer material is preferably selected from spiro-OMeTAD, P3HT, PTAA, etc., and more preferably spiro-OMeTAD.

[0076] In the present application, the hole transport layer material preferably further comprises;

[0077] Chlorobenzene, lithium salt solution, and TBP.

[0078] In the present application, the lithium salt solution preferably comprises: Li-TFSI and acetonitrile.

[0079] In the present application, the amount ratio of Li-TFSI and acetonitrile is preferably (50-55) mg:(80-120) μL, more preferably (52-53) mg:100 μL.

[0080] In the present application, the amount ratio of the hole transport layer material, chlorobenzene, lithium salt solution and TBP is preferably (70-75) mg:(0.5-1.5) mL:(17-20) μL:(25-30) μL, more preferably (72-73) mg:(0.8-1.2) mL:(17-18) μL:(28-29) μL, most preferably 72.3 mg:1 mL:17.5 μL:28.8 μL.

[0081] In the present application, the deposition method is preferably selected from spin coating, blade coating, spray coating, slot coating, screen printing, evaporation, CVD and the like, more preferably spin coating, and the spin coating speed is preferably 3500-4500 rpm, more preferably 3800-4200 rpm, most preferably 4000 rpm.

[0082] In the present application, the electrode preparation method preferably comprises:

[0083] Depositing electrode material on the surface of the hole transport layer.

[0084] In the present application, the electrode material is preferably selected from metal materials such as gold, silver, copper and the like, and carbon materials such as graphene, amorphous carbon and the like.

[0085] In the present application, the deposition method is preferably selected from magnetron sputtering, electron beam evaporation, thermal evaporation, atomic layer deposition, pulsed laser deposition, evaporation and the like, preferably evaporation, and the evaporation process is preferably carried out in a high vacuum environment, and the vacuum degree is preferably <5×10 -4 Pa, and the evaporation speed is preferably More preferably

[0086] The present application provides a perovskite solar cell based on one-step preparation of color electronic transport layer, which is different from the existing template method and photolithography colorization technology, the present application uses gas phase deposition method to prepare titanium dioxide nanosheet array in situ on the conductive substrate, which utilizes the scattering and diffraction effect of visible light wavelength, and displays a specific color, and uses it as perovskite electronic transport layer to construct a color perovskite solar cell.

[0087] Example 1

[0088] The FTO transparent conductive glass was cut into 1 cm x 1 cm pieces, and was ultrasonically cleaned in ionized water, acetone, and ethanol for 20 min, respectively, and was dried with nitrogen and stored for later use.

[0089] A seed layer was prepared, and a metal Ti seed layer was deposited on the surface of the above conductive substrate by thermal evaporation, the cavity was vacuumed to 4.0E -4 Pa, the cavity temperature was 200°C, and the evaporation rate was 0.2 A / s. The thickness was 10 nm.

[0090] An electron transport layer was prepared, and a titanium dioxide nanosheet array electron transport layer was prepared on the surface of the above seed layer by chemical vapor deposition, the Ti source was titanium acetylacetonate, which was placed in a low-temperature zone (230°C), the substrate on which the metal Ti seed layer was deposited was placed in a high-temperature zone (500°C), the low-temperature zone was connected by a quartz tube, and N2 / O2 (O2 volume content 1%) mixed gas was introduced, and the reaction was performed for 1 h, and the substrate was taken out after being cooled to room temperature, to obtain a titanium dioxide array with a thickness of 200 nm.

[0091] A perovskite layer was deposited on the surface of the above electron transport layer, 10 ml of a perovskite layer (composition: 3.688 g PbI2, 1.376 g FAI) precursor solution with a molar concentration of 0.8 M was configured, the solvent was NMP, and the perovskite active layer was prepared on the surface of the TiO2 electron transport layer by using a doctor blade method, the doctor blade speed was 12 mm / s, and the perovskite layer was annealed at 150°C for 20 min, and the final thickness of the perovskite layer was 450 nm.

[0092] A hole transport layer was prepared, and a hole transport layer was prepared on the surface of the above perovskite layer, 72.3 mg of spiro-OMeTAD was weighed, dissolved in 1 mL of chlorobenzene, 17.5 μL of lithium salt solution (52 mg of Li-TFSI was weighed and dissolved in 100 μL of acetonitrile) and 28.8 μL of TBP were added, respectively, and the clear solution was obtained by stirring overnight, and was spin-coated on the surface of the perovskite layer at a speed of 4000 rpm, and the thickness was 100 nm.

[0093] A top electrode was deposited, and a metal Ag electrode layer was prepared on the surface of the above hole transport layer by evaporation, and the metal Ag was evaporated onto the surface of the hole transport layer in a high vacuum (<5 x 10 - 4 Pa) environment, the evaporation rate was 0.2 A / s. The thickness was 100 nm, and a perovskite solar cell was obtained.

[0094] Example 2

[0095] The FTO transparent conductive glass was cut into 1 cm x 1 cm pieces, and was ultrasonically cleaned in ionized water, acetone, and ethanol for 20 min, respectively, and was dried with nitrogen and stored for later use.

[0096] A seed layer was prepared, a metal Ti seed layer was deposited on the surface of the above conductive substrate by thermal evaporation, the cavity vacuum was 4.0E-3 Pa, the cavity temperature was 200°C, and the evaporation rate was 0.5 A / s. -4 Pa, the cavity temperature was 200°C, and the evaporation rate was 0.5 A / s. The thickness was 20 nm.

[0097] An electron transport layer was prepared, a titanium dioxide nanosheet array electron transport layer was prepared by chemical vapor deposition, a titanium acetylacetonate source was placed in a low-temperature zone (230°C), the substrate on which the metal Ti seed layer was deposited was placed in a high-temperature zone (500°C), the low-temperature zone was connected by a quartz tube, and N2 / O2 (O2 volume content 1%) mixed gas was introduced, reaction was performed for 1 h, and after being taken out after being reduced to room temperature, a titanium dioxide array with a thickness of 250 nm was obtained.

[0098] A perovskite layer was deposited on the above electron transport layer, a perovskite layer (composition: 3.688 g of PbI2 and 1.376 g of FAI) precursor solution with a molar concentration of 0.8 M was configured, NMP was used as the solvent, a perovskite active layer was prepared on the surface of the TiO2 electron transport layer by using a doctor blade method, the doctor blade speed was 12 mm / s, annealing was performed at 150°C for 20 minutes, and finally a perovskite layer with a thickness of 450 nm was obtained.

[0099] A hole transport layer was prepared, a hole transport layer was prepared on the surface of the above perovskite layer, 72.3 mg of spiro-OMeTAD was weighed and dissolved in 1 mL of chlorobenzene, 17.5 μL of a lithium salt solution (52 mg of Li-TFSI was weighed and dissolved in 100 μL of acetonitrile) and 28.8 μL of TBP were added, respectively, and a clear solution was obtained after stirring overnight, and the solution was spin-coated on the surface of the perovskite layer at a speed of 4000 rpm, and the thickness was 100 nm.

[0100] A top electrode was deposited, a metal Ag electrode layer was prepared by evaporation on the surface of the above hole transport layer, and the metal Ag was evaporated onto the surface of the hole transport layer in a high vacuum (<5×10 - 4 Pa) environment, the evaporation rate was 0.5 A / s. The thickness was 100 nm, and a perovskite solar cell was obtained.

[0101] Example 3

[0102] The FTO transparent conductive glass was cut into 1 cm x 1 cm pieces, and was ultrasonically cleaned in ionized water, acetone and ethanol for 20 min, respectively, and was dried with nitrogen and stored for standby use.

[0103] A seed layer was prepared, a metal Ti seed layer was deposited on the surface of the above conductive substrate by thermal evaporation, the cavity vacuum was 4.0E-3 Pa, the cavity temperature was 200°C, and the evaporation rate was 0.5 A / s. -4 Pa, the cavity temperature was 200°C, and the evaporation rate was 0.5 A / s. The thickness was 10 nm.

[0104] The electronic transport layer is prepared, and the titanium dioxide nanosheet array electronic transport layer is prepared by chemical vapor deposition. The Ti source is titanium acetylacetonate, which is placed in a low temperature zone (185 DEG C). The substrate with a metal Ti seed layer is placed in a high temperature zone (400 DEG C). The low temperature zone is connected by a quartz tube, and N2 / O2 (O2 volume content 1%) mixed gas is introduced. The reaction is carried out for 1 hour. After being cooled to room temperature, the titanium dioxide array with a thickness of 100 nm is obtained.

[0105] The perovskite layer is deposited on the surface of the electronic transport layer. A perovskite layer (the composition is 3.688g PbI2, 1.376g FAI) precursor solution with a molar concentration of 0.8M is configured, and NMP is used as a solvent. The perovskite active layer is prepared on the surface of the TiO2 electronic transport layer by using a doctor blade method. The doctor blade speed is 12mm / s. The perovskite layer is annealed at 150 DEG C for 20 minutes, and the final thickness of the perovskite layer is 450nm.

[0106] The hole transport layer is prepared. The hole transport layer is prepared on the surface of the perovskite layer. 72.3mg of spiro-OMeTAD is weighed and dissolved in 1mL of chlorobenzene. 17.5μL of lithium salt solution (52mg of Li-TFSI is weighed and dissolved in 100μL of acetonitrile) and 28.8μL of TBP are added, respectively. The clear solution is obtained by stirring overnight. The solution is spin-coated on the surface of the perovskite layer at a speed of 4000rpm, and the thickness of the hole transport layer is 100nm.

[0107] The top electrode is deposited. The metal Ag electrode layer is prepared by evaporation on the surface of the hole transport layer. The metal Ag is evaporated on the surface of the hole transport layer in a high vacuum environment (<5*10 -4 Pa). The evaporation speed is 0.1A. The thickness of the perovskite solar cell is 100nm.

[0108] Performance detection

[0109] The electronic transport layer (including transparent conductive glass, metal Ti seed layer and titanium dioxide nanosheet array transport layer) prepared in the embodiment is tested by using an ultraviolet-visible spectrophotometer. The reflection spectrum test (including reflection peak position and half-wave width) is carried out. The detection results are as follows. It can be seen that the color can be controlled by changing the reaction conditions (such as the thickness of the seed layer and the vapor deposition temperature).

[0110] Parameters Example 1 Example 2 Example 3 Reflection peak position (nm) 520 470 430 Half wave width (nm) 62 43 65 Color Green Cyan Blue

[0111] The application provides a perovskite solar cell based on a one-step method for preparing a color electronic transport layer. Different from existing colorization technologies such as a template method and a photolithography method, the application adopts a vapor deposition method to prepare a titanium dioxide nanosheet array on a conductive substrate in situ. The titanium dioxide nanosheet array utilizes scattering and diffraction effects for visible light wavelengths, displays a specific color, and is used as a perovskite electronic transport layer to construct a color perovskite solar cell.

[0112] While the application has been described and illustrated with reference to specific embodiments thereof, those skilled in the art will appreciate that various adaptations, changes, modifications, substitutions, developments, improvements, and permutations can be made in the specific embodiments described in this application without departing from the true spirit and scope of the application, as defined by the appended claims. All such modifications are intended to be within the scope of the claims. Although methods disclosed herein have been described with reference to particular operations performed in a particular order, it will be understood that these operations can be combined, sub-divided, or re-ordered to form equivalent methods without departing from the teachings of the present application. Accordingly, unless specifically indicated herein, the order and grouping of operations are not a limitation of this application.

Claims

1. An electron transport layer, comprising: Base; A metallic Ti seed layer is disposed on the surface of the substrate; An array of titanium dioxide nanosheets disposed on the surface of the Ti seed layer; The titanium dioxide nanosheets in the titanium dioxide nanosheet array have a thickness of 10–40 nm and a length of 100 nm–1.5 μm.

2. The electron transport layer according to claim 1, characterized in that, The thickness of the metallic Ti seed layer is 5–20 nm.

3. The electron transport layer according to claim 1, characterized in that, The total thickness of the Ti seed layer and the titanium dioxide nanosheet array is 200–500 nm.

4. A method for preparing the electron transport layer according to claim 1, comprising: A metallic Ti seed layer is prepared on the substrate surface; Titanium dioxide nanosheet arrays were prepared on the surface of the Ti seed layer by chemical vapor deposition.

5. The method according to claim 4, characterized in that, The method for preparing the metallic Ti seed layer is selected from thermal evaporation, magnetron sputtering, or atomic layer deposition.

6. The method according to claim 4, characterized in that, In the chemical vapor deposition process, the Ti source is placed in a low-temperature zone, and the substrate is located in a high-temperature zone. The low-temperature zone is connected by a quartz tube, through which a N2 / O2 mixed gas is introduced.

7. The method according to claim 6, characterized in that, The Ti source is selected from one or more of titanium acetylacetonate, titanium tert-butoxide, methyl titanate, and isopropyl titanate.

8. The method according to claim 6, characterized in that, The temperature of the low-temperature zone is 100–300°C, the temperature of the high-temperature zone is 400–800°C, and the volume content of O2 in the N2 / O2 mixed gas is 1–5%.

9. A perovskite solar cell, comprising: The electronic transport layer as described in claim 1; A perovskite layer disposed on the surface of the titanium dioxide nanosheet array of the electron transport layer; Hole transport layer disposed on the surface of the perovskite layer; Electrodes disposed on the surface of the hole transport layer.

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