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

Abstract

The invention discloses a method for preparing a perovskite thin film in air based on tridecafluoroheptyl ethylene oxide, and belongs to the technical field of semiconductors. The method comprises the following steps: firstly, preparing a PbI2 precursor solution and an organic ammonium salt isopropanol solution, and then adding perdecafluoroheptyl ethylene oxide into the PbI2 precursor solution; a two-step sequential deposition method is adopted, the perovskite thin film is prepared in air, a PbI2 precursor solution added with perfluoroheptyl ethylene oxide is spin-coated, a PbI2 thin film growing on a highly layered surface is obtained after annealing, an organic ammonium salt solution is further spin-coated on the PbI2 surface, and the perovskite thin film is formed through solid-liquid reaction annealing. The residual amount of PbI2 in the high-quality perovskite thin film prepared by the method is reduced, crystal grains are obviously increased, and crystal boundaries are reduced. The photoelectric conversion efficiency of the perovskite solar cell prepared based on the method is also obviously improved, and the method has certain guiding significance for preparing the large-area perovskite solar cell in the air.

Description

Technical Field

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

[0002] Organic metal lead-based hybrid perovskites have high light absorption coefficients, long carrier lifetimes, and adjustable band gaps, which have attracted great research attention. Solar cells prepared based on this material have achieved a certified power conversion efficiency (PCE) of up to 27%. Despite the rapid development of perovskite solar cells (PSCs), the high-efficiency perovskite solar cells reported so far are mainly prepared in glove boxes, which have strict requirements on control conditions, hindering the low-cost commercial development of perovskite photovoltaics.

[0003] The two-step sequential deposition method for preparing perovskite films does not require an anti-solvent and exhibits good operational stability. Compared with the traditional one-step deposition method, it is more suitable for preparing perovskite films in air. However, moisture in the air will destroy the pre-deposited PbI 2 layer, which in turn affects the crystal quality and defect state density of the final prepared perovskite film, thus causing problems such as ion migration, non-radiative recombination and perovskite body decomposition. Therefore, improving the PbI 2 Film quality is regarded as the key to further improve the efficiency and stability of PSCs prepared in air.

[0004] In order to improve PbI 2 Film quality, existing technology proposes to regulate PbI 2 Film morphology and crystallization process to obtain loose and porous PbI 2 The morphology enables the subsequently deposited organic ammonium salt to penetrate into the pores and promote the pre-deposited PbI 2 However, in order to prevent moisture in the air from reacting with PbI 2 The adverse effects of thin films still require the preparation of PbI in an inert atmosphere. 2 Thin films cannot really be prepared in the air. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention proposes a method for preparing perovskite film in air based on tridecafluoroheptyl ethylene oxide, using tridecafluoroheptyl ethylene oxide as an additive to regulate the PbI 2 Crystal growth kinetics, induced PbI 2 The film grows in a highly layered manner, which improves its resistance to water erosion and promotes the crystallization process of the perovskite film, thus achieving efficient and high-quality preparation of perovskite films in air.

[0006] The method for preparing perovskite films in air based on tridecafluoroheptylethylene oxide first uses a mixture of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) to dissolve PbI 2 , preparation of PbI 2 Precursor solution, then to PbI 2 1~5μL of tridecafluoroheptyl oxirane was added to the precursor solution. Then FAI, MAI and MACl were dissolved in isopropanol solvent and stirred until completely dissolved to obtain an isopropanol solution of organic ammonium salt. PbI mixed with tridecafluoroheptyl oxirane was spin-coated on the substrate surface in an air environment. 2 Precursor solution and organic ammonium salt isopropanol solution, FA is obtained after annealing 0.92 MA 0.08 PbI 3 Perovskite thin films.

[0007] A method for preparing a perovskite cell in air based on tridecafluoroheptyl ethylene oxide, wherein a perovskite film is prepared by a two-step sequential deposition method in air, and 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 to obtain an electron transport layer.

[0010] Step 3: Dissolve PbI using a mixture of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) 2 , preparation of PbI 2 Precursor solution, then add 1~5μL of tridecafluoroheptyl oxirane. Dissolve FAI, MAI and MACl in isopropanol solvent and stir until completely dissolved to obtain an isopropanol solution of organic ammonium salt.

[0011] Step 4: First, spin-coat PbI mixed with tridecafluoroheptyl ethylene oxide on the surface of the electron transport layer. 2 The precursor solution is annealed and cooled to room temperature, and then spin-coated with an organic ammonium salt isopropanol solution, and the perovskite film is obtained after annealing.

[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 diluted tin dioxide (SnO 2 ) solution, the spin coating speed is 3000~5000 rpm, the annealing temperature is 150 ℃, the time is 30 minutes, and the thickness of the obtained electron transport layer is 20~30 nanometers.

[0014] Preferably, PbI 2 The spin coating speed of the 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, spin-coated PbI 2 The precursor solution was then annealed at 70 °C for 1 min, and an organic ammonium salt isopropanol solution was spin-coated and annealed at 150 °C for 15 min.

[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 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.

[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 and has a thickness of 100 nanometers.

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

[0021] The present invention uses tridecafluoroheptyl ethylene oxide additive to regulate the pre-deposition of PbI 2 The crystal growth and morphology of the film are induced by the interaction between the oxygen atoms on tridecafluoroheptyl oxirane and the lead atoms in the precursor solution. 2 The film is highly layered. In addition, the fluorine substituent on tridecafluoroheptyl oxirane can form hydrogen bonds with organic cations in the isopropanol solution of organic ammonium salt, promoting better bonding of organic ammonium salt with PbI 2 The films react with each other and synergistically regulate the crystal quality of the perovskite film, achieving the preparation of high-quality, high-stability, and high-reproducibility perovskite films in the air, thereby further improving the efficiency and stability of perovskite solar cells prepared in the air. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0024] Figure 3 PbI in Example 1 and Comparative Example 1 2 Surface SEM image of the film.

[0025] Figure 4 2 is the XRD diagram of the perovskite film 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 is a method for preparing a perovskite film in air based on tridecafluoroheptylethylene oxide, and the comparative examples and embodiments are prepared as follows: Figure 1 The formal planar structure (NIP) of a perovskite solar cell is shown as an example.

[0028] Comparative Example 1

[0029] The perovskite solar cell was prepared by a conventional two-step sequential deposition method in air. 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, and then perform plasma treatment for 15 minutes after drying. The square resistance of the ITO conductive glass is about 7Ω.

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

[0032] Step 3: 691.5 mg of PbI 2 Dissolve in 1 mL of DMF and DMSO mixed solvent in a volume ratio of 9:1 to prepare PbI 2 Precursor solution: Dissolve 90 mg FAI, 7 mg MAI and 9 mg MACl in 1 mL of isopropanol solvent and stir until completely dissolved to obtain an isopropanol solution of organic ammonium salt.

[0033] Step 4: First, spin-coat PbI on the surface of the electron transport layer 2 The precursor solution was prepared at an ambient temperature of 26 °C and a relative humidity of 30 ± 5%. The spin coating speed was 2000 rpm for 30 seconds. After spin coating, the solution was heated at 70 °C for 1 minute to obtain PbI 2 After cooling to room temperature, the PbI 2The film surface was spin-coated with an organic ammonium salt isopropanol solution at a 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.

[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 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 spiro-OMeTAD solution and evenly coat it on the surface post-treated perovskite film at a spin coating speed of 4000 rpm for 30 seconds to obtain 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 at a degree of vacuum less than 1 × 10 -4 bar, Ag electrode was evaporated to a thickness of 100 nanometers to obtain a perovskite solar cell.

[0037] Comparative Example 2

[0038] In an inert atmosphere (N 2 The perovskite solar cell is prepared in a glove box, and the specific steps are 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: SnO 2 The dispersion was diluted in deionized water at a volume ratio of 1:3, and then spin-coated on the plasma-treated ITO conductive glass surface at 5000 rpm. After 30 seconds, it was annealed at 150°C for 30 minutes to obtain an electron transport layer with a thickness of 20 nm.

[0041] Step 3: 691.5 mg of PbI 2 Dissolve in 1 mL of DMF and DMSO mixed solvent in a volume ratio of 9:1 to prepare PbI 2Precursor solution: Dissolve 90 mg FAI, 7 mg MAI and 9 mg MACl in 1 mL of isopropanol solvent and stir until completely dissolved to obtain an isopropanol solution of organic ammonium salt.

[0042] Step 4: In N 2 In the glove box, spin-coat PbI on the surface of the electron transport layer 2 The precursor solution was spin-coated at a speed of 2000 rpm for 30 seconds and heated at 70 °C for 1 minute to obtain PbI 2 After cooling to room temperature, the PbI 2 An organic ammonium salt isopropanol solution was spin-coated on the surface of the film at a speed of 2000 rpm for 30 seconds, and then heated 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 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 spiro-OMeTAD solution and evenly coat it on the surface post-treated perovskite film at a spin coating speed of 4000 rpm for 30 seconds to obtain 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 at a degree of vacuum less than 1 × 10 -4 bar, Ag electrode was evaporated to a thickness of 100 nanometers 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 ethylene oxide, and 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: SnO 2 The dispersion was diluted in deionized water at a volume ratio of 1:3, and then spin-coated on the plasma-treated ITO conductive glass surface at 5000 rpm. After 30 seconds, it was annealed at 150°C for 30 minutes to obtain an electron transport layer with a thickness of 20 nm.

[0050] Step 3: 691.5 mg of PbI 2 Dissolve in 1 mL of DMF and DMSO mixed solvent in a volume ratio of 9:1 to prepare PbI 2 The precursor solution was then added with 1 μL of tridecafluoroheptyl oxirane, the structural formula of tridecafluoroheptyl oxirane being shown in formula (I):

[0051] (I)

[0052] 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 an organic ammonium salt.

[0053] Step 4: First, spin-coat PbI mixed with tridecafluoroheptyl ethylene oxide on the surface of the electron transport layer. 2 The precursor solution was prepared at an ambient temperature of 26°C and a relative humidity of 30±5%. The spin coating speed was 2000 rpm for 30 seconds. After spin coating, it was heated at 70°C for 1 minute to obtain PbI 2 film.

[0054] The PbI prepared in Comparative Example 1 and Example 1 was analyzed by X-ray diffractometer (XRD). 2 Thin film crystallization process, such as Figure 2 As shown, in Example 1, PbI prepared by adding tridecafluoroheptyl ethylene oxide 2 The peak intensity of each layered crystal plane of the film, including (001), (002), and (003) crystal planes, is significantly higher than that of PbI prepared in Comparative Example 1. 2 Film, after adding tridecafluoroheptyl ethylene oxide, PbI 2 The crystallinity of the film layer surface is good. In addition, in Example 1, PbI 2 The intensity of the (110) crystal plane diffraction peak of the film 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 PbI 2 The grains mainly grow continuously along the layered planes, presenting an ordered array structure.

[0055] Comparative Example 1 and Example 1 prepared PbI 2 The film was tested by scanning electron microscopy (SEM), and the results were as follows Figure 3 As shown, it can be seen that PbI prepared by adding tridecafluoroheptyl oxirane in Example 1 2 The film surface is smoother, the grain boundary contours are clearer, and it shows a highly layered surface growth, which is consistent with the XRD test results.

[0056] After cooling to room temperature, PbI 2 The film surface was spin-coated with an organic ammonium salt isopropanol solution at a 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.

[0057] The XRD test analysis of the perovskite film morphology prepared in Comparative Example 1 and Example 1 showed that Figure 4 As shown in the figure, it can be seen that the PbI 2 The characteristic peak intensity of the perovskite main crystal plane (2 diffraction angle = 14.2°) is significantly reduced, while the characteristic peak intensity of the perovskite main crystal plane (2 diffraction angle = 14.2°) is significantly enhanced, indicating that the highly layered growth of PbI 2 It helps the growth of perovskite grains and promotes the crystallization process of perovskite films.

[0058] The perovskite films obtained in Comparative Example 1 and Example 1 were subjected to SEM examination, and the results are as follows: Figure 5 As shown in the figure, 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 the highly layered growth of PbI 2 It can promote the penetration of subsequently deposited organic ammonium salts and react with them to form perovskite, thereby obtaining a high-quality perovskite film.

[0059] 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.

[0060] 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 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 spiro-OMeTAD solution and evenly coat it on the surface post-treated perovskite film at a spin coating speed of 4000 rpm for 30 seconds to obtain a hole transport layer.

[0061] Step 7: Place the product obtained in step 6 into a vapor deposition chamber and place it in a vacuum chamber at a degree of vacuum less than 1 × 10 -4 bar, Ag electrode was evaporated to a thickness of 100 nanometers to obtain a perovskite solar cell.

[0062] Example 2

[0063] This example introduces a method for preparing a perovskite battery in air based on tridecafluoroheptyl ethylene oxide. On the basis of Example 1, PbI 2 Add 3 μL of tridecafluoroheptyl oxirane to the precursor solution.

[0064] Example 3

[0065] This example introduces a method for preparing a perovskite battery in air based on tridecafluoroheptyl ethylene oxide. On the basis of Example 1, PbI 2 Add 5 μL of tridecafluoroheptylethylene oxide to the precursor solution.

[0066] The perovskite solar cells prepared in the above comparative examples and embodiments were subjected to a solar simulator at a standard solar intensity (AM1.5G, 100 mW / cm 2 ) was used to perform an electrical performance test. The solar simulator used a standard silicon cell to calibrate the light intensity before the test. The results are shown in Table 1:

[0067] Table 1

[0068] It can be seen from the data in Table 1 that compared with Comparative Example 1, Examples 1 to 3 2The open circuit voltage, short circuit current density and photoelectric conversion efficiency of the obtained solar cell are improved by adding tridecafluoroheptyl oxirane to the precursor solution. Compared with Comparative Example 2, the efficiency of the perovskite solar cells prepared in Examples 1 to 3 in the air is comparable to that of the perovskite devices prepared in an inert gas, indicating that the use of tridecafluoroheptyl oxirane as an additive can regulate the quality of the perovskite film crystal, which has a certain guiding significance for the preparation of large-area perovskite solar cells in the air.

Claims

1. A method for preparing a perovskite film in air based on tridecafluoroheptyl ethylene oxide, wherein a PbI2 precursor solution and an organic ammonium salt isopropanol solution are prepared, and a two-step sequential deposition method is used to prepare a perovskite film in air, characterized in that: Tridecafluoroheptyl oxirane is added to the prepared PbI2 precursor solution, and a two-step sequential deposition method is used in air to spin-coat the PbI2 precursor solution with tridecafluoroheptyl oxirane and an isopropanol solution of an organic ammonium salt in sequence, and a perovskite film is obtained after solid-liquid reaction annealing.

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

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

4. The method for preparing a perovskite film in air based on tridecafluoroheptylethylene oxide according to claim 1, characterized in that: 691.5 mg of PbI2 was dissolved in 1 mL of a solution of N,N-dimethylformamide and dimethyl sulfoxide mixed in a volume ratio of 9:1, 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 tridecafluoroheptylethylene oxide according to claim 1, characterized in that: 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 tridecafluoroheptylethylene oxide according to claim 1, characterized in that: 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 battery in air based on tridecafluoroheptylethylene oxide, wherein an electron transport layer, a perovskite film, a hole transport layer and a metal back electrode are sequentially deposited on the surface of a plasma-treated conductive glass to obtain a perovskite battery; 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 tridecafluoroheptylethylene oxide as claimed in claim 7, characterized in that: The electron transport material is a diluted tin dioxide solution, which is spin-coated on the surface of the conductive glass 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 tridecafluoroheptylethylene oxide as claimed in 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 the hole transport layer was prepared.

10. The method for preparing a perovskite battery in air based on tridecafluoroheptylethylene oxide as claimed in 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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