Perovskite thin film and preparation method and application thereof

Abstract

The invention relates to the technical field of solar cells, in particular to a perovskite thin film and a preparation method and application thereof, the perovskite thin film is prepared by a two-step method, and after a metal halide thin film is prepared, a passivator is pre-spin-coated on the metal halide thin film to obtain a pre-spin coating. The purpose of the pre-spin-coating process is to repair or supplement the metal halide thin film which may be changed or damaged due to heat treatment by covering the metal halide thin film again after annealing, so that the defect density is reduced, and the consistency and quality stability in the perovskite thin film preparation process can be ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cells, and in particular to a perovskite film and a preparation method and application thereof. Background Art

[0002] Directly constructing 2D / 3D structured perovskites or defect passivation will face the problem of insufficient passivation. Due to its semi-insulating nature, 2D perovskites usually require a very thin thickness to ensure good charge transfer with the electron transport layer. However, this very thin thickness often leads to the formation of a discontinuous covering layer of the surface 2D perovskite prepared by the solution method. The 3D perovskite area that is not completely covered still has a large number of surface defects, which affects the performance of the device. In addition, this double-layer device will damage the 3D perovskite structure after annealing, reducing the performance of the device. Therefore, improving the crystallinity of perovskite films and reducing the initial defect density are important aspects that researchers need to pay attention to. Summary of the invention

[0003] The purpose of the present invention is to provide a perovskite film and a preparation method and application thereof, so as to solve the technical problem in the prior art that the crystallinity of the perovskite film cannot be improved and the initial defect density cannot be reduced.

[0004] The invention discloses a method for preparing a perovskite film. The perovskite film is prepared by a two-step method, wherein after the metal halide film is prepared, a passivating agent solution is pre-spin-coated on the metal halide film to obtain a pre-spin coating.

[0005] Furthermore, the two-step method for preparing the perovskite film is to first prepare the metal halide film and then prepare the organic halide film.

[0006] Furthermore, the metal halide film is a lead iodide layer.

[0007] Furthermore, the metal halide film is prepared by dissolving PbI2, PbBr2, CsI, PbCl2 and DMAI in DMF and DMSO solvents.

[0008] Furthermore, the volume ratio of DMF to DMSO is 9:1.

[0009] DMAI: Dimethylammonium iodide

[0010] DMSO: Dimethyl sulfoxide

[0011] DMF: N,N-Dimethylformamide

[0012] Furthermore, the metal halide film is spin-coated for 30 seconds at a spin-coating speed of 2500 rpm / s and an acceleration of 2500 rpm / s. 2 .

[0013] Furthermore, the organic halide film is a FAI layer.

[0014] Furthermore, the organic halide film is prepared by dissolving FAI, MABr and MACl in isopropanol.

[0015] FAI:Formamidinium iodide

[0016] MABr: Methylammonium bromide

[0017] MACl: Methylammonium chloride

[0018] Furthermore, the organic halide film is spin-coated for 30 seconds at a spin-coating speed of 2700 rpm / s and an acceleration of 2700 rpm / s. 2 Finally, annealing was performed at 150°C for 15 minutes to obtain the FAI layer.

[0019] Furthermore, the passivation agent solution is spin-coated on the metal halide film for 10-30 seconds, the spin-coating speed is 1500-5000 rpm / s, and the acceleration is 1500-5000 rpm / s. 2 , the spin coating is completed and a pre-spin coating is obtained.

[0020] Furthermore, an organic halide film is spin-coated on the pre-spin coating layer.

[0021] Furthermore, the passivator solution is spin-coated again on the organic halide film to obtain a passivator layer.

[0022] Furthermore, the passivating agent solution is prepared by mixing phenethylammonium iodide, methylamine ethanol and isopropanol.

[0023] Furthermore, 1-30 uL of methylamine ethanol is added to every 1-10 mg of the phenethylammonium iodide, and isopropanol is used as a solvent.

[0024] Furthermore, 1-30 uL of methylamine ethanol is added for every 1-5 mg of the phenethylammonium iodide.

[0025] A perovskite film is prepared using the method.

[0026] An application of a perovskite film for preparing a perovskite solar cell.

[0027] Furthermore, the following steps are included:

[0028] S1. Pretreatment of conductive glass;

[0029] S2. Preparing an electron transport layer;

[0030] S3. Two-step method for preparing perovskite thin films;

[0031] S4. Preparing a hole transport layer;

[0032] S5. Prepare metallic silver electrode.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. After the lead iodide layer is prepared in the first step, MES (MethylaMine ethanol solution) + PEAI (2-phenylethanamine iodide) is applied on the lead iodide layer to complete the pre-spin coating process. The purpose of this process is to repair or replenish the lead iodide layer that may have changed or damaged due to heat treatment by re-covering the lead iodide layer after annealing, thereby reducing the defect density and helping to ensure consistency and quality stability in the preparation of perovskite films. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only represent some embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 This is a scanning electron microscope image (SEM) of Comparative Example 1 of the present invention.

[0037] Figure 2 This is the SEM of Example 3 of the present invention.

[0038] Figure 3 PL test spectra of Example 3 and Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0040] Example 1

[0041] A perovskite film and a preparation method and application thereof of the above-mentioned device used in this embodiment include the following steps:

[0042] (1) Pretreatment of conductive glass

[0043] The conductive glass was ultrasonically cleaned for 30 minutes using deionized water and conductive glass cleaning solution, anhydrous ethanol and isopropanol in a volume ratio of 20:1, and finally dried with nitrogen for later use.

[0044] (2) Preparation of electron transport layer

[0045] Dilute the tin dioxide hydrosol with deionized water at a fixed ratio of 1:3, ultrasonicate for 30 minutes, filter with a 0.22 μm nylon filter, and store at room temperature for later use. Take 70 μL of the solution and drop it on the pretreated conductive glass, spin-coating at a speed of 4000 rpm / s and an acceleration of 2000 rpm / s. 2 , spin coating for 30 seconds, and finally annealing at 180°C for 20 minutes to obtain the electron transport layer.

[0046] (3) Preparation of wide bandgap perovskite layer and passivation layer

[0047] Prepare a passivating agent by mixing 2 mg of phenethylammonium iodide, 5 uL of methylamine ethanol solution and 1 mL of isopropanol, and dissolve it at room temperature for 4 hours for later use.

[0048] Step 1: Dissolve 553.2mg PbI2, 110.1mg PbBr2, 77.943mg CsI, 10.42mg PbCl2, and 2.6mg (1% molar concentration) DMAI in 1mL DMF and DMSO solvent (DMF:DMSO = 9:1), dissolve at room temperature for 8h. Take 45uL of the solution and spin coat it on the electron transport layer for 30s, with a spin coating speed of 2500rpm / s and an acceleration of 2500rpm / s. 2 ; Finally, anneal at 70℃ for 30s to obtain a PbI2 layer. Then, take 70uL of the solution and spin coat the PbI2 layer for 30s at a spin coating speed of 5000rpm / s and an acceleration of 5000rpm / s. 2 , spin coating is completed and the first passivation layer is obtained.

[0049] Step 2: Dissolve 90 mg FAI, 9 mg MABr, and 9 mg MACl in 1 mL isopropanol and dissolve at room temperature for 4 hours. Take 70 uL of the solution and spin coat the PbI2 layer for 30 seconds at a speed of 2700 rpm / s and an acceleration of 2700 rpm / s. 2 Finally, anneal at 150°C for 15 minutes to obtain the FAI layer. Then, 70uL of the solution was spin-coated on the FAI layer for 30 seconds at a spin-coating speed of 5000rpm / s and an acceleration of 5000rpm / s.2 After the spin coating, annealing was performed at 70°C for 5 min to obtain the second passivation layer.

[0050] (4) Preparation of hole transport layer 2

[0051] Mix 72.3 mg Spiro-OMeTAD, 28.8 uL tert-butylpyridine (TBP) and 28.8 uL Li-TFSI solution and dissolve them in 1 mL chlorobenzene. Dissolve them at room temperature for 2 hours. Spin 45 uL of the solution on the defect passivation layer for 30 seconds at a speed of 3000 rpm / s and an acceleration of 3000 rpm / s. 2 , the spin coating is completed to obtain a hole transport layer.

[0052] (5) Preparation of metallic silver electrodes

[0053] A vacuum evaporation device was used to deposit 200 nm thick metallic silver. The prepared device was placed in a water-free drying oven for post-oxidation treatment, and the battery performance parameters were tested after 48 hours.

[0054] Embodiment 2:

[0055] The only difference between this embodiment and embodiment 1 is that the amount of methylamine ethanol solution in step (3) is replaced with 10 uL.

[0056] Embodiment 3:

[0057] The only difference between this embodiment and embodiment 1 is that the amount of methylamine ethanol solution in step (3) is replaced with 15 uL.

[0058] Embodiment 4:

[0059] The only difference between this embodiment and embodiment 1 is that the amount of methylamine ethanol solution in step (3) is replaced with 20 uL.

[0060] Embodiment 5:

[0061] The only difference between this embodiment and Embodiment 1 is that MES is not added and only PEAI is used.

[0062] Comparative Example 1:

[0063] The only difference between this comparative example and Example 1 is that no pre-spin coating is prepared.

[0064] On a JV test instrument, 0.105 square centimeters of perovskite solar cells provided in the embodiment and the comparative example were tested based on a standard light intensity of one sun. The starting voltage of the JV test was set to 1.2 V, the ending voltage was set to -0.2 V, the scanning step was 0.02 V, and the delay time was set to 20 ms.

[0065] The above examples and comparative examples were subjected to performance tests and the test results are shown in Table 1.

[0066] Table 1

[0067] <![CDATA[V OC (V)]]> <![CDATA[J SC (mA / cm 2 )]]> FF(%) PCE(%) Example 1 1.173 21.55 78.90 19.96 Example 2 1.189 21.59 79.86 20.51 Example 3 1.204 21.38 80.40 20.70 Example 4 1.176 21.35 78.95 19.83 Example 5 1.185 21.47 79.66 19.79 Comparative Example 1 1.168 21.57 76.68 19.32

[0068] Among them, V OC -Open circuit voltage; J SC -short circuit current density; FF-fill factor; PCE-photovoltaic conversion efficiency.

[0069] It can be seen from Table 1 that the wide bandgap perovskite solar cells provided by the embodiments of the present invention and the comparative examples have high photoelectric conversion efficiency (19.52%-20.70%). After pre-spin coating, the device performance including open circuit voltage, fill factor, and photoelectric conversion efficiency are significantly improved; however, when the amount of MES is too much, the efficiency improvement decreases, so the perovskite battery system needs to match the appropriate MES concentration; the synergistic passivation effect of MES+PEAI pre-spin coating is better than the effect of using only PEAI pre-spin coating.

[0070] from Figure 1 and Figure 2 It can be found that after pre-spin coating with a passivating agent, more and more evenly distributed white blocky substances appear at the grain boundaries of the perovskite film compared to the control film. We speculate that this is a small amount of residual PbI2. In the control group image, PbI2 presents a larger and more concentrated distribution. After pre-spin coating, large pieces of lead iodide are significantly reduced, and a smaller and more even distribution appears. In perovskite films, if large pieces of lead iodide are distributed at the perovskite grain boundaries and gradually refine, it can bring multiple benefits. First, this helps to improve the crystallinity of the perovskite film, thereby improving carrier mobility, reducing charge recombination, and thus improving the performance of optoelectronic devices. Secondly, lead iodide, as a dopant, can optimize the optoelectronic properties of perovskite films and improve the photoelectric conversion efficiency. In addition, this process may also enhance the stability of perovskite films and reduce the density of lattice and grain boundary defects, which is beneficial to improving the long-term stability and optoelectronic performance of devices.

[0071] from Figure 3 , PL test spectrum, it can be found that the PL intensity of the film without pre-spin coating is significantly lower than that of the perovskite film treated by the pre-spin coating process, indicating that the pre-spin coating process can effectively inhibit non-radiative recombination

[0072] The above are the implementation methods listed in this embodiment, but this embodiment is not limited to the above optional implementation methods. Those skilled in the art can arbitrarily combine the above methods to obtain other various implementation methods. Anyone can derive other various forms of implementation methods under the inspiration of this embodiment. The above specific implementation methods should not be understood as limiting the scope of protection of this embodiment. The scope of protection of this embodiment shall be based on the definition in the claims, and the description can be used to interpret the claims.

Claims

1. A method for preparing a perovskite film, characterized in that: The perovskite film is prepared using a two-step method, wherein after the metal halide film is prepared, a passivation agent solution is pre-spin-coated on the metal halide film to obtain a pre-spin coating.

2. The method for preparing a perovskite thin film according to claim 1, characterized in that: The two-step method for preparing the perovskite film is to first prepare the metal halide film and then prepare the organic halide film.

3. The method for preparing a perovskite thin film according to claim 2, characterized in that: The metal halide film is a lead iodide layer.

4. The method for preparing a perovskite thin film according to claim 2, characterized in that: The organic halide film is a FAI layer.

5. The method for preparing a perovskite thin film according to claim 1, characterized in that: The passivation agent solution is spin-coated on the metal halide film for 10-30 seconds, the spin-coating speed is 1500-5000 rpm / s, and the acceleration is 1500-5000 rpm / s. 2 , the spin coating is completed and a pre-spin coating is obtained.

6. The method for preparing a perovskite thin film according to claim 1, characterized in that: An organic halide film is spin-coated on the pre-spin coating layer.

7. The method for preparing a perovskite film according to any one of claims 1 to 6, characterized in that: The passivating agent solution is prepared by mixing phenethylammonium iodide, methylamine ethanol and isopropanol.

8. The method for preparing a perovskite film according to claim 7, characterized in that: 1-30 uL of methylamine ethanol is added for every 1-10 mg of the phenethylammonium iodide, and the isopropanol is used as a solvent.

9. A perovskite film, characterized in that: The perovskite film is prepared using the method for preparing the perovskite film according to any one of claims 1 to 8.

10. The use of a perovskite film according to claim 9, characterized in that: Used to prepare perovskite solar cells.

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