Method for preparing perovskite film in air based on tridecafluoroheptyl ethylene oxide

Abstract

The present invention discloses a method for preparing a perovskite film in the air based on tridecafluoroheptyl oxirane, and belongs to the field of semiconductor technology. The method first configures a PbI2 precursor solution and an organic ammonium salt isopropyl alcohol solution, and then adds tridecafluoroheptyl oxirane to the PbI2 precursor solution. A two-step sequential deposition method is used to prepare a perovskite film in the air. The PbI2 precursor solution with tridecafluoroheptyl oxirane added is first spin-coated, and after annealing, a PbI2 film with a high degree of layered surface growth is obtained. An organic ammonium salt solution is further spin-coated on the PbI2 surface, and a perovskite film is formed by solid-liquid reaction annealing. The high-quality perovskite film prepared by this method has a reduced amount of PbI2 residue inside, significantly increased grains, and reduced grain boundaries. The photoelectric conversion efficiency of the perovskite solar cell prepared based on this method is also significantly improved, which has certain guiding significance for preparing large-area perovskite solar cells in the air.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor technology and relates to the preparation of perovskite solar cells, and in particular to a method for preparing a perovskite film in air based on tridecafluoroheptyl ethylene oxide. Technical Background

[0002] Organic metal lead-based hybrid perovskites have attracted significant research attention due to their high light absorption coefficient, long carrier lifetime, and tunable band gap. Solar cells fabricated using these materials have achieved certified power conversion efficiencies (PCEs) as high as 27%. Despite the rapid development of perovskite solar cells (PSCs), the high-efficiency PSCs reported so far have primarily been fabricated in glove boxes, requiring stringent control conditions, hindering the low-cost commercialization of PSCs.

[0003] The two-step sequential deposition method for preparing perovskite films does not require an antisolvent and exhibits excellent operational stability, making it more suitable for preparing perovskite films in air than the traditional one-step deposition method. However, moisture in the air can damage the pre-deposited PbI2 layer, thereby affecting the crystal quality and defect state density of the final perovskite film, leading to problems such as ion migration, non-radiative recombination, and perovskite decomposition. Therefore, improving the quality of the PbI2 film during the two-step sequential deposition process is considered key to further improving the efficiency and stability of PSCs prepared in air.

[0004] To improve the quality of PbI2 films, existing techniques propose manipulating the film morphology and crystallization process to achieve a loose, porous PbI2 morphology. This allows subsequently deposited organic ammonium salts to penetrate the pores and promote reaction with the pre-deposited PbI2. However, to avoid the adverse effects of moisture in the air on the PbI2 film, the PbI2 film must still be prepared in an inert atmosphere, making it impossible to truly prepare perovskite films in air. Summary of the Invention

[0005] In response to the shortcomings of the existing technology, the present invention proposes a method for preparing perovskite films in air based on tridecafluoroheptylethylene oxide. Tridecafluoroheptylethylene oxide is used as an additive to regulate the crystallization growth kinetics of PbI2, induce the highly layered growth of PbI2 films, improve their resistance to water erosion, and promote the crystallization process of perovskite films, thereby realizing efficient and high-quality preparation of perovskite films in air.

[0006] The method for preparing perovskite films in air based on tridecafluoroheptyl oxirane is as follows: first, PbI2 is dissolved in a mixture of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) to prepare a PbI2 precursor solution, and then 1~5μL of tridecafluoroheptyl oxirane is added to the PbI2 precursor solution. FAI, MAI and MACl are then dissolved in isopropanol solvent and stirred until completely dissolved to obtain an organic ammonium salt isopropanol solution. The PbI2 precursor solution mixed with tridecafluoroheptyl oxirane and the organic ammonium salt isopropanol solution are spin-coated on the substrate surface in an air environment, and FA is obtained after annealing. 0.92 MA 0.08 PbI3 perovskite thin film.

[0007] A method for preparing a perovskite cell in air based on tridecafluoroheptyl ethylene oxide is described. A two-step sequential deposition method is used to prepare a perovskite film in air. The specific steps are as follows:

[0008] Step 1: ultrasonically clean the conductive glass with deionized water, acetone, and ethanol in sequence, and then perform plasma treatment after drying.

[0009] Step 2: spin-coating an electron transport material on the surface of the plasma-treated conductive glass and annealing the coating to obtain an electron transport layer.

[0010] Step 3: Prepare a PbI2 precursor solution by dissolving PbI2 in a mixture of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). Then, add 1–5 μL of tridecafluoroheptyloxirane. Dissolve FAI, MAI, and MACl in isopropanol and stir until completely dissolved to obtain an isopropanol solution of the organic ammonium salts.

[0011] Step 4: First, a PbI2 precursor solution mixed with tridecafluoroheptyl oxirane is spin-coated on the surface of the electron transport layer, annealed and cooled to room temperature, and then spin-coated with an organic ammonium salt isopropanol solution. After annealing, a perovskite film is obtained.

[0012] Step 5: Prepare a hole transport layer on the surface of the perovskite film, and finally evaporate a metal back electrode on the hole transport layer to complete the preparation of the perovskite cell.

[0013] Preferably, the electron transport material is a diluted tin dioxide (SnO2) solution, the spin coating speed is 3000-5000 rpm, the annealing temperature is 150°C, the time is 30 minutes, and the obtained electron transport layer thickness is 20-30 nm.

[0014] Preferably, the spin coating speed of the PbI2 precursor solution and the organic ammonium salt isopropanol solution is 1500-2000 rpm, the time is 30 seconds, the ambient temperature is 26-30 degrees, and the relative humidity is 20-40%.

[0015] Preferably, after spin coating the PbI2 precursor solution, the substrate is annealed at 70°C for 1 minute, and after spin coating the organic ammonium salt isopropanol solution, the substrate is annealed at 150°C for 15 minutes.

[0016] Preferably, the o-FPEAI / IPA solution is spin-coated onto the surface of the perovskite film for post-treatment, and then the hole transport layer is prepared.

[0017] Preferably, the hole transport layer has a thickness of 180-200 nm and is obtained by spin coating a spiro-OMeTAD solution on the surface of the perovskite film at a spin coating speed of 3000-5000 rpm for 30 seconds.

[0018] Preferably, spiro-OMeTAD is dissolved in chlorobenzene, and then Li-TFSI / acetonitrile solution and 4-tert-butylpyridine are added to obtain a spiro-OMeTAD solution.

[0019] Preferably, the metal back electrode is Ag with a thickness of 100 nanometers.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention utilizes a tridecafluoroheptyloxirane additive to regulate the crystal growth and morphology of a pre-deposited PbI2 thin film. The interaction between the oxygen atoms on the tridecafluoroheptyloxirane and the lead atoms in the precursor solution induces the highly layered growth of the PbI2 film. Furthermore, the fluorine substituents on the tridecafluoroheptyloxirane can form hydrogen bonds with organic cations in an isopropanol solution of an organic ammonium salt, promoting better interaction between the organic ammonium salt and the PbI2 film. This synergistically regulates the crystal quality of the perovskite film, enabling the preparation of high-quality, highly stable, and highly reproducible perovskite films in air, thereby further improving the efficiency and stability of perovskite solar cells prepared in air. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the structure of a perovskite solar cell.

[0023] Figure 2 2 are XRD patterns of the PbI2 films in Example 1 and Comparative Example 1.

[0024] Figure 3 Surface SEM images of the PbI2 films in Example 1 and Comparative Example 1.

[0025] Figure 4 2 are XRD patterns of the perovskite films in Example 1 and Comparative Example 1.

[0026] Figure 5 Surface SEM images of the perovskite films in Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0027] The following describes the method for preparing perovskite film in air based on tridecafluoroheptyl ethylene oxide with reference to the accompanying drawings. Figure 1 The formal planar structure (NIP) perovskite solar cell shown is taken as an example.

[0028] Comparative Example 1

[0029] Perovskite solar cells were prepared in air using a conventional two-step sequential deposition method. The specific steps are as follows:

[0030] Step 1: ultrasonically clean the etched ITO conductive glass with deionized water, acetone, and ethanol for 15 minutes, dry it, and then plasma treat it for 15 minutes. The sheet resistance of the ITO conductive glass is about 7Ω.

[0031] Step 2: Dilute the SnO2 dispersion in deionized water at a volume ratio of 1:3, and then spin-coat it on the plasma-treated ITO conductive glass surface at 5000 rpm. After 30 seconds, anneal it at 150°C for 30 minutes to obtain an electron transport layer with a thickness of 20 nm.

[0032] Step 3: Prepare a PbI2 precursor solution by dissolving 691.5 mg of PbI2 in 1 mL of a 9:1 volume ratio DMF / DMSO mixture. Dissolve 90 mg of FAI, 7 mg of MAI, and 9 mg of MACl in 1 mL of isopropanol and stir until completely dissolved to obtain an isopropanol solution of the organic ammonium salt.

[0033] Step 4: First, spin-coat the PbI2 precursor solution on the surface of the electron transport layer at an ambient temperature of 26°C and a relative humidity of 30±5% at a speed of 2000 rpm for 30 seconds. After spin-coating, heat the film at 70°C for 1 minute to obtain a PbI2 film. After cooling to room temperature, spin-coat an organic ammonium salt isopropanol solution on the surface of the PbI2 film at a speed of 2000 rpm for 30 seconds. Then, heat the film at 150°C for 15 minutes at a relative humidity of 30±5% to obtain a perovskite film.

[0034] Step 5. Weigh 5 mg of o-fluorophenylethylamine iodide (o-FPEAI), use 1 mL of isopropyl alcohol (IPA) as a solvent, stir at room temperature for 2 hours, prepare an o-FPEAI / IPA solution with a concentration of 5 mg / mL, and spin-coat the o-FPEAI / IPA solution onto the surface of the perovskite film at a spin-coating speed of 5000 rpm for 30 seconds, then heat at 100 °C for 5 minutes to obtain a surface-post-treated perovskite film.

[0035] Step 6. Weigh 520 mg of Li-TFSI and dissolve it in 1 mL of acetonitrile. Weigh 72.3 mg of spiro-OMeTAD and dissolve it in 1 mL of chlorobenzene. Then, add 20 μL of the Li-TFSI / acetonitrile solution and 30 μL of 4-tert-butylpyridine to obtain a spiro-OMeTAD solution. Use a pipette to draw 50 mL of the spiro-OMeTAD solution and evenly coat it on the surface-post-treated perovskite film. Spin-coat at 4000 rpm for 30 seconds to form a hole transport layer.

[0036] Step 7: Place the product obtained in step 6 into a vapor deposition chamber and place it in a vacuum chamber of less than 1 × 10 -4 bar, an Ag electrode was evaporated to a thickness of 100 nm to obtain a perovskite solar cell.

[0037] Comparative Example 2

[0038] The perovskite solar cells were prepared in an inert atmosphere (N2 glove box) as follows:

[0039] Step 1: ultrasonically clean the etched ITO conductive glass with deionized water, acetone, and ethanol for 15 minutes, and then perform plasma treatment for 15 minutes after drying.

[0040] Step 2: Dilute the SnO2 dispersion in deionized water at a volume ratio of 1:3, and then spin-coat it on the plasma-treated ITO conductive glass surface at 5000 rpm. After 30 seconds, anneal it at 150°C for 30 minutes to obtain an electron transport layer with a thickness of 20 nm.

[0041] Step 3: Prepare a PbI2 precursor solution by dissolving 691.5 mg of PbI2 in 1 mL of a 9:1 volume ratio DMF / DMSO mixture. Dissolve 90 mg of FAI, 7 mg of MAI, and 9 mg of MACl in 1 mL of isopropanol and stir until completely dissolved to obtain an isopropanol solution of the organic ammonium salt.

[0042] Step 4: In an N2 glove box, spin-coat the electron transport layer with a PbI2 precursor solution at a speed of 2000 rpm for 30 seconds. Heat the solution at 70°C for 1 minute to obtain a PbI2 film. After cooling to room temperature, spin-coat the PbI2 film with an organic ammonium salt in isopropanol at a speed of 2000 rpm for 30 seconds. Heat the film at 150°C for 15 minutes to obtain a perovskite film.

[0043] Step 5. Weigh 5 mg of o-fluorophenylethylamine iodide (o-FPEAI), use 1 mL of isopropyl alcohol (IPA) as a solvent, stir at room temperature for 2 hours, prepare an o-FPEAI / IPA solution with a concentration of 5 mg / mL, and spin-coat the o-FPEAI / IPA solution onto the surface of the perovskite film at a spin-coating speed of 5000 rpm for 30 seconds, then heat at 100 °C for 5 minutes to obtain a surface-post-treated perovskite film.

[0044] Step 6. Weigh 520 mg of Li-TFSI and dissolve it in 1 mL of acetonitrile. Weigh 72.3 mg of spiro-OMeTAD and dissolve it in 1 mL of chlorobenzene. Then, add 20 μL of the Li-TFSI / acetonitrile solution and 30 μL of 4-tert-butylpyridine to obtain a spiro-OMeTAD solution. Use a pipette to draw 50 mL of the spiro-OMeTAD solution and evenly coat it on the surface-post-treated perovskite film. Spin-coat at 4000 rpm for 30 seconds to form a hole transport layer.

[0045] Step 7: Place the product obtained in step 6 into a vapor deposition chamber and place it in a vacuum chamber of less than 1 × 10 -4 bar, an Ag electrode was evaporated to a thickness of 100 nm to obtain a perovskite solar cell.

[0046] Example 1

[0047] This example introduces a method for preparing a perovskite battery in air based on tridecafluoroheptyl oxirane. The specific steps are as follows:

[0048] Step 1: ultrasonically clean the etched ITO conductive glass with deionized water, acetone, and ethanol for 15 minutes, and then perform plasma treatment for 15 minutes after drying.

[0049] Step 2: Dilute the SnO2 dispersion in deionized water at a volume ratio of 1:3, and then spin-coat it on the plasma-treated ITO conductive glass surface at 5000 rpm. After 30 seconds, anneal it at 150°C for 30 minutes to obtain an electron transport layer with a thickness of 20 nm.

[0050] Step 3: Dissolve 691.5 mg of PbI2 in 1 mL of a 9:1 volume ratio DMF and DMSO mixed solvent to prepare a PbI2 precursor solution, and then add 1 μL of tridecafluoroheptyl oxirane. The structural formula of tridecafluoroheptyl oxirane is shown in Formula (I):

[0051]

[0052] (I)

[0053] 90 mg of FAI, 7 mg of MAI, and 9 mg of MACl were dissolved in 1 mL of isopropanol solvent and stirred until completely dissolved to obtain an isopropanol solution of organic ammonium salts.

[0054] Step 4: First, spin-coat the surface of the electron transport layer with a PbI2 precursor solution mixed with tridecafluoroheptyl oxirane. The ambient temperature is 26°C, the relative humidity is 30±5%, the spin-coating speed is 2000 rpm, and the time is 30 seconds. After spin-coating, heat at 70°C for 1 minute to obtain a PbI2 thin film.

[0055] The crystallization process of the PbI2 thin films prepared in Comparative Example 1 and Example 1 was analyzed by X-ray diffractometer (XRD). Figure 2 As shown in the figure, the peak intensities of the various layered crystal planes of the PbI2 film prepared in Example 1 by adding tridecafluoroheptyl oxirane, including the (001), (002), and (003) crystal planes, are significantly higher than those of the PbI2 film prepared in Comparative Example 1. After adding tridecafluoroheptyl oxirane, the crystallinity of the layered planes of the PbI2 film is better. In addition, the diffraction peak intensity of the (110) crystal plane of the PbI2 film in Example 1 is significantly reduced. Since the (110) crystal plane grows perpendicular to the layered plane, the reduction of the (110) crystal plane diffraction peak indicates that the PbI2 grains in Example 1 mainly grow continuously along the layered plane, presenting an ordered array structure.

[0056] The PbI2 films prepared in Comparative Example 1 and Example 1 were tested by scanning electron microscopy (SEM). Figure 3 As shown, it can be seen that the surface of the PbI2 film prepared by adding tridecafluoroheptyl ethylene oxide in Example 1 is smoother, the grain boundary contours are clearer, and it shows a high degree of layered surface growth, which is consistent with the XRD test results.

[0057] After cooling to room temperature, an organic ammonium salt isopropanol solution was spin-coated on the surface of the PbI2 film at a spin-coating speed of 2000 rpm for 30 seconds, and then heated at 150 °C for 15 minutes at a relative humidity of 30±5% to obtain a perovskite film.

[0058] The XRD test analysis of the perovskite film morphology prepared in Comparative Example 1 and Example 1 showed that Figure 4 As shown, it can be seen that the characteristic peak intensity of PbI2 (2 diffraction angle = 12.8°) in the perovskite film prepared by adding tridecafluoroheptyl ethylene oxide in Example 1 is significantly reduced, while the characteristic peak intensity of the main crystal plane of the perovskite (2 diffraction angle = 14.2°) is significantly enhanced, indicating that the highly layered growth of PbI2 is conducive to the growth of perovskite grains and promotes the crystallization process of the perovskite film.

[0059] The perovskite films obtained in Comparative Example 1 and Example 1 were subjected to SEM examination, and the results were as follows: Figure 5 As shown, the grain size of the perovskite film prepared by adding tridecafluoroheptyl ethylene oxide in Example 1 is significantly increased and the grain boundaries are reduced, which verifies that the highly layered growth of PbI2 can promote the penetration of the subsequently deposited organic ammonium salt and react with it to form perovskite, thereby obtaining a high-quality perovskite film.

[0060] Step 5. Weigh 5 mg of o-fluorophenylethylamine iodide (o-FPEAI), use 1 mL of isopropyl alcohol (IPA) as a solvent, stir at room temperature for 2 hours, prepare an o-FPEAI / IPA solution with a concentration of 5 mg / mL, and spin-coat the o-FPEAI / IPA solution onto the surface of the perovskite film at a spin-coating speed of 5000 rpm for 30 seconds, then heat at 100 °C for 5 minutes to obtain a surface-post-treated perovskite film.

[0061] Step 6. Weigh 520 mg of Li-TFSI and dissolve it in 1 mL of acetonitrile. Weigh 72.3 mg of spiro-OMeTAD and dissolve it in 1 mL of chlorobenzene. Then, add 20 μL of the Li-TFSI / acetonitrile solution and 30 μL of 4-tert-butylpyridine to obtain a spiro-OMeTAD solution. Use a pipette to draw 50 mL of the spiro-OMeTAD solution and evenly coat it on the surface-post-treated perovskite film. Spin-coat at 4000 rpm for 30 seconds to form a hole transport layer.

[0062] Step 7: Place the product obtained in step 6 into a vapor deposition chamber and place it in a vacuum chamber of less than 1 × 10 -4 bar, an Ag electrode was evaporated to a thickness of 100 nm to obtain a perovskite solar cell.

[0063] Example 2

[0064] This example introduces a method for preparing a perovskite battery in air based on tridecafluoroheptyl oxirane. Based on Example 1, 3 μL of tridecafluoroheptyl oxirane is added to the PbI2 precursor solution.

[0065] Example 3

[0066] This example introduces a method for preparing a perovskite battery in air based on tridecafluoroheptyl oxirane. Based on Example 1, 5 μL of tridecafluoroheptyl oxirane is added to the PbI2 precursor solution.

[0067] The perovskite solar cells prepared in the above comparative examples and examples were tested using a solar simulator at a standard solar intensity (AM1.5G, 100 mW / cm 2) were used to conduct electrical performance tests. The solar simulator was used to calibrate the light intensity using a standard silicon cell before the test. The results are shown in Table 1:

[0068] Table 1

[0069]

[0070] As can be seen from the data in Table 1, compared to Comparative Example 1, Examples 1-3, by adding tridecafluoroheptyloxirane to the PbI2 precursor solution, all improved the open circuit voltage, short circuit current density, and photoelectric conversion efficiency of the solar cells obtained. Compared to Comparative Example 2, the efficiency of the perovskite solar cells prepared in air in Examples 1-3 is comparable to that of perovskite devices prepared in an inert gas, indicating that the use of tridecafluoroheptyloxirane as an additive can regulate the quality of perovskite thin film crystals, which has certain guiding significance for the preparation of large-area perovskite solar cells in air.

Claims

1. A method for preparing perovskite thin films in air based on tridecafluoroheptyl ethylene oxide, comprising preparing a PbI2 precursor solution and an organic ammonium salt isopropanol solution, and preparing the perovskite thin film by a two-step sequential deposition method in air, characterized in that: Tridecafluoroheptyl oxirane was added to the prepared PbI2 precursor solution, and a two-step sequential deposition method was used in air to spin-coat the PbI2 precursor solution with tridecafluoroheptyl oxirane and an organic ammonium salt isopropanol solution in turn. After solid-liquid reaction annealing, a perovskite film was obtained.

2. The method for preparing a perovskite film in air based on tridecafluoroheptyloxirane according to claim 1, wherein: A mixed N,N-dimethylformamide and dimethyl sulfoxide are used as a solvent to dissolve PbI2 to prepare a PbI2 precursor solution.

3. The method for preparing a perovskite film in air based on tridecafluoroheptyloxirane according to claim 1, wherein: Dissolve FAI, MAI and MACl in isopropanol solvent and stir until completely dissolved to obtain an isopropanol solution of organic ammonium salts.

4. The method for preparing a perovskite film in air based on tridecafluoroheptylethylene oxide according to claim 1, wherein: 691.5 mg of PbI2 was dissolved in 1 mL of a 9:1 volume ratio mixture of N,N-dimethylformamide and dimethyl sulfoxide, and then 1-5 μL of tridecafluoroheptyl oxirane was added. 90 mg of FAI, 7 mg of MAI, and 9 mg of MACl were dissolved in 1 mL of isopropanol solvent to prepare an isopropanol solution of an organic ammonium salt. FA was prepared in air using a two-step sequential deposition method. 0.92 MA 0.08 PbI3 perovskite thin film.

5. The method for preparing a perovskite film in air based on tridecafluoroheptyloxirane according to claim 1, wherein: The spin coating speed of the PbI2 precursor solution and the organic ammonium salt isopropanol solution is 1500-2000 rpm, the time is 30 seconds, the ambient temperature is 26-30 degrees, and the relative humidity is 20-40%.

6. The method for preparing a perovskite film in air based on tridecafluoroheptyloxirane according to claim 1, wherein: After spin coating the PbI2 precursor solution, the substrate was annealed at 70 °C for 1 minute. After spin coating the organic ammonium salt isopropanol solution, the substrate was annealed at 150 °C for 15 minutes.

7. A method for preparing a perovskite cell in air based on tridecafluoroheptyl oxirane, wherein an electron transport layer, a perovskite film, a hole transport layer, and a metal back electrode are sequentially deposited on a plasma-treated conductive glass surface to obtain a perovskite cell; characterized in that: The perovskite film is prepared by the method according to any one of claims 1 to 6.

8. The method for preparing a perovskite battery in air based on tridecafluoroheptyl oxirane according to claim 7, characterized in that: The diluted tin dioxide solution was spin-coated on the conductive glass surface at a speed of 3000-5000 rpm, and then annealed at 150°C for 30 minutes to obtain an electron transport layer with a thickness of 20-30 nanometers.

9. The method for preparing a perovskite battery in air based on tridecafluoroheptyl oxirane according to claim 7, characterized in that: 5 mg / mL o -FPEAI / IPA solution was spin-coated onto the surface of the perovskite film, post-treated, and then a hole transport layer was prepared.

10. The method for preparing a perovskite battery in air based on tridecafluoroheptyl oxirane according to claim 9, characterized in that: The hole transport layer has a thickness of 180-200 nanometers and is obtained by spin-coating a spiro-OMeTAD solution on the surface of the perovskite film at a spin-coating speed of 3000-5000 rpm for 30 seconds.

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