A tin-lead perovskite thin film containing TAP-OH, its preparation method and application

Abstract

This invention belongs to the field of new energy and optoelectronic functional materials technology, and discloses a tin-lead perovskite thin film containing TAP-OH, its preparation method, and its application. The raw materials for preparing this tin-lead perovskite thin film include a tin-lead perovskite precursor solution, and the tin-lead perovskite precursor solution contains a TPA-OH additive. The chemical structure of the TPA-OH additive is shown in the formula. This invention introduces a TPA-OH additive into the tin-lead perovskite precursor solution. This additive is a triphenylamine derivative containing phenolic hydroxyl groups and vinyl groups. The vinyl groups can undergo in-situ polymerization during perovskite crystallization and form a film at the grain boundaries, effectively blocking the penetration of oxygen and moisture and the migration channels for defects. The phenolic hydroxyl groups and Sn... 2+ Coordination reduces oxidation tendency and defect formation, effectively suppressing degradation pathways. Therefore, the film of this invention exhibits excellent morphological stability and long-term battery stability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of new energy and photoelectric functional materials, and particularly relates to a tin-lead perovskite film containing TAP-OH and a preparation method and application thereof. BACKGROUND

[0002] Metal halide perovskites have rapidly become important candidate materials for high-efficiency photovoltaic devices and novel optoelectronic devices in recent years due to their strong light absorption coefficient, long carrier diffusion length and defect tolerance. Among them, tin-lead (Sn-Pb) mixed halide perovskites can be adjusted to a narrow band gap of about 1.2-1.3 eV by partially introducing Sn at the Pb site, which is more suitable as a single-junction high-current output absorption layer or a bottom cell absorption layer of a full perovskite tandem cell, helping to break through the efficiency bottleneck of traditional silicon solar cells, and also having the potential advantage of low toxicity. Therefore, Sn-Pb mixed perovskites have been widely used in photovoltaic and optoelectronic devices under single-junction, tandem and other high-bias conditions. However, the chemical instability of Sn 2+ is one of the core bottlenecks limiting the development and industrialization of Sn-Pb perovskites. On the one hand, Sn 2+ is easily oxidized to Sn 4+ in the air or oxygen-containing environment, inducing a large number of Sn vacancies in the lattice and causing serious p-type self-doping; on the other hand, Sn-related defects often form deep level traps, enhancing non-radiative recombination, which significantly limits the open-circuit voltage of Sn-Pb devices and significantly reduces the stability.

[0003] In the prior art, reducing agents such as SnF2, SnCl2, etc. or “physical packaging” ideas can inhibit oxidation to some extent, but there are often problems such as limited protection time, easy enrichment of insulating phases at grain boundaries, and impact on carrier transport, which are difficult to be sustained and effective in the whole life cycle of “solution configuration → crystallization into film → device long-term operation”.

[0004] Therefore, it is urgent to develop an additive suitable for metal halide perovskite precursors, so that the tin-lead perovskite film has good structural stability and also has chemical passivation and physical sealing functions. SUMMARY

[0005] The present application aims to at least solve one of the technical problems existing in the prior art. To this end, the present application proposes a tin-lead perovskite film containing TAP-OH and a preparation method and application thereof, which has excellent morphology stability and long-term battery stability, and is suitable for high-performance narrow-bandgap perovskite photovoltaic devices.

[0006] To solve the above-mentioned technical problems, the first aspect of the present invention provides a tin-lead perovskite thin film, wherein the raw materials for preparing the tin-lead perovskite thin film include a tin-lead perovskite precursor solution, the tin-lead perovskite precursor solution containing a TPA-OH additive, and the chemical structure of the TPA-OH additive is shown in formula (1): (1).

[0007] Specifically, this invention introduces a TPA-OH additive into a tin-lead perovskite precursor solution. This additive is a triphenylamine derivative containing phenolic hydroxyl groups and vinyl groups. The vinyl groups can undergo in-situ polymerization during perovskite crystallization and selectively locate at grain boundaries, forming a stable cross-linked encapsulation network. This physically blocks the main channels for oxygen and moisture diffusion along grain boundaries, thereby improving the chemical and structural stability of the film. The phenolic hydroxyl groups possess electron-donating capabilities and can react with Sn in the precursor solution. 2+ Coordination reduces its oxidation to Sn. 4+ The tendency of Sn to degrade effectively inhibits the degradation pathway of the film; the triphenylamine electron donor structure is beneficial to improving free radical stability, thereby enhancing the antioxidant capacity of the film. Therefore, the tin-lead perovskite film of the present invention can significantly inhibit Sn degradation in the early stage of film formation. 2+ Oxidation exhibits excellent morphological stability and long-term battery stability, making it suitable for high-performance narrow-bandgap perovskite photovoltaic devices.

[0008] In some embodiments of the present invention, the concentration of the TPA-OH additive in the tin-lead perovskite precursor solution is 0.1-5 mg / mL; preferably, the concentration of the TPA-OH additive in the tin-lead perovskite precursor solution is 0.3-3 mg / mL; more preferably, the concentration of the TPA-OH additive in the tin-lead perovskite precursor solution is 0.5-1 mg / mL.

[0009] In some embodiments of the present invention, the tin-lead perovskite film contains tin-lead halide perovskite, and the general chemical formula of the tin-lead mixed halide perovskite is: FA 1-x MA x Pb 1-y Sn y X3; where: FA represents formamidinium, MA represents methylamine, and X represents halogen; the ranges of x and y are respectively: 0 <x≤0.5,0<y≤0.8。

[0010] In some embodiments of the present invention, X is selected from I and / or Br.

[0011] In some embodiments of the present invention, the values ​​of x and y are respectively: 0.2≤x≤0.4, 0.4≤y≤0.6.

[0012] In some embodiments of the present invention, the chemical formula of the tin-lead mixed halide perovskite is FA. 0.7 MA 0.3 Pb 0.5 Sn 0.5 I3.

[0013] A second aspect of the present invention provides a method for preparing the above-mentioned tin-lead perovskite thin film, comprising the following steps: A solution of tin-lead perovskite precursor containing TPA-OH additive is coated onto a substrate, and then annealed to allow the TPA-OH additive to undergo a polymerization reaction, thereby obtaining the tin-lead perovskite film.

[0014] In some embodiments of the present invention, the coating method is a two-step spin coating method, wherein: the first step is to spin coat at a speed of 800-1200 rpm for 8-12 seconds, the second step is to spin coat at a speed of 3500-4500 rpm for 35-45 seconds, and at 20-30 seconds of the second step, chlorobenzene anti-solvent is added dropwise.

[0015] In some embodiments of the present invention, the annealing temperature is 80-120°C, and the annealing time is 15-25 minutes. During the annealing process, due to the higher surface energy and stronger polarity at the grain boundaries, TPA-OH molecules will preferentially accumulate in the grain boundary region, and the vinyl groups in the molecules will crosslink into a film under thermal action, constructing a linear or network polymer structure.

[0016] In some embodiments of the present invention, the preparation process of the tin-lead perovskite precursor solution includes the following steps: taking FAX, MAX, PbX2 and SnX2 according to the stoichiometric ratio in the general chemical formula, dissolving them in an organic solvent; adding TPA-OH additive, mixing, and obtaining the solution.

[0017] In some embodiments of the present invention, the organic solvent is a mixed solution of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), wherein the volume ratio of DMF to DMSO is (2-4):1.

[0018] In some embodiments of the present invention, the concentration of the solution formed by dissolving FAX, MAX, PbX2 and SnX2 in an organic solvent is 1-3 mol / L; preferably 1.5-2.5 mol / L.

[0019] A third aspect of the present invention provides a photovoltaic device comprising the aforementioned tin-lead perovskite thin film.

[0020] Compared with the prior art, the above-described technical solution of the present invention has at least the following technical effects or advantages: (1) This invention introduces a TPA-OH additive into the tin-lead perovskite precursor solution. This additive is a triphenylamine derivative containing phenolic hydroxyl groups and vinyl groups. The vinyl groups can undergo in-situ polymerization during the perovskite crystallization process and preferentially form a film at the grain boundaries, effectively blocking the penetration of oxygen and moisture and the migration channels of defects; the phenolic hydroxyl groups and Sn 2+ Coordination reduces oxidation tendency and defect formation, effectively suppressing degradation pathways. Therefore, the film of this invention exhibits excellent morphological stability and long-term battery stability.

[0021] (2) The TPA-OH additive of the present invention can exert an oxidation blocking effect in the solution stage and film crystallization process, and significantly inhibit Sn. 2+ Oxidation, in fresh films, Sn 4+ The ratio can be as low as 3.82%. At the same time, the cross-linked polymer network physically blocks the main channels for oxygen and moisture to diffuse along the grain boundaries, allowing the device to maintain more than 80% of its initial efficiency after being stored in a dark nitrogen environment for 3600 hours.

[0022] (3) When the tin-lead perovskite thin film of the present invention is applied to photovoltaic devices, the open-circuit voltage and fill factor of the device can be significantly improved without changing the main crystal structure and bandgap width, and the output can be stabilized. It is suitable for various Sn-Pb ratios and common p / i / n device structures; and it is compatible with conventional crystallization processes. Attached Figure Description

[0023] Figure 1 The image shows the 1H NMR spectrum of compound 1. Figure 2 The image shows the carbon NMR spectrum of compound 1. Figure 3 The image shows the 1H NMR spectrum of compound 2. Figure 4 The image shows the carbon NMR spectrum of compound 2. Figure 5 The image shows the 1H NMR spectrum of compound 3. Figure 6 The image shows the carbon NMR spectrum of compound 3. Figure 7 SEM images of the tin-lead perovskite films prepared in Example 1 and Comparative Example 1; Figure 8 XRD patterns of the tin-lead perovskite films prepared in Example 1 and Comparative Example 1; Figure 9 XPS images of the tin-lead perovskite films prepared in Example 1 and Comparative Example 1; Figure 10 JV curves for photovoltaic devices prepared in Application Example 1 and Comparative Application 1; Figure 11The graphs show the dark storage stability test curves of the photovoltaic devices prepared in Application Example 1 and Comparative Application 1. Detailed Implementation

[0024] The present invention will now be described in detail with reference to embodiments to facilitate understanding of the invention by those skilled in the art. It is particularly important to note that the embodiments are merely illustrative of the invention and should not be construed as limiting the scope of protection of the invention. Non-essential improvements and adjustments made to the invention by those skilled in the art based on the above description should still fall within the scope of protection of the invention. Furthermore, all raw materials mentioned below, unless otherwise specified, are commercially available products; all process steps or preparation methods not mentioned in detail are process steps or preparation methods known to those skilled in the art.

[0025] Example 1 A method for preparing a tin-lead perovskite thin film includes the following steps: (1) The synthesis route and steps of the TPA-OH additive are as follows:

[0026] 1) Synthesis of 2,6-di-tert-butyl-4-(diphenylamino)phenol (compound 1) In a 250 mL round-bottom flask, diphenylamine (3.38 g, 20 mmol), 4-bromo-2,6-di-tert-butylphenol (6.84 g, 24 mmol), Pd2(dba)3 (0.55 g, 0.6 mmol), potassium tert-butoxide (4.49 g, 40 mmol, t-BuOK), and P(t-Bu)3·HBF4 (0.24 g, 0.83 mmol) were added and dissolved in 100 mL of toluene. The reaction system was subjected to three vacuum-argon purging treatments, then heated to 110 °C under argon protection and stirred overnight. After the reaction was complete, water was added to quench the reaction, and the mixture was extracted with dichloromethane. The organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The crude product was purified by silica gel column chromatography (ethyl acetate / petroleum ether = 1:5) to give a white solid product (compound 1) in 85.5% yield.

[0027] Compound 1 1 H NMR, 13 The results of C NMR and mass spectrometry are as follows: Figures 1-2 As shown, the structure of the obtained product is consistent with that of the target compound.

[0028] 2) Synthesis of 4,4′-((3,5-di-tert-butyl-4-hydroxyphenyl)azono)dibenzaldehyde (compound 2) In a 25 mL round-bottom flask, compound 1 (2.0 g, 5.35 mmol) was dissolved in 10 mL of DMF, and POCl3 (5 mL) was slowly added dropwise under ice bath conditions. After three vacuum-argon purging treatments, the system was reacted under argon protection for 12 h, followed by heating to 80 °C and stirring for another 12 h. After the reaction was completed, the mixture was cooled to room temperature, quenched with cold water, extracted with dichloromethane, dried and concentrated the organic phase, and purified by silica gel column chromatography (ethyl acetate / petroleum ether = 1:4) to give a yellow solid product (compound 2) in 75% yield.

[0029] Compound 2 1 H NMR, 13 The results of C NMR and mass spectrometry are as follows: Figures 3-4 As shown, the data further confirms the successful introduction of the target aldehyde structure.

[0030] 3) Synthesis of 4-(bis(4-vinylphenyl)amino)-2,6-di-tert-butylphenol (TPA-OH, compound 3) In a 25 mL round-bottom flask, methyltriphenylphosphine bromide (2.1 g, 5.82 mmol) and potassium tert-butoxide (0.65 g, 5.82 mmol) were dissolved in tetrahydrofuran (THF). After stirring in an ice bath for 30 min, compound 2 (1.0 g, 2.33 mmol) was slowly added. The system was subjected to three vacuum-argon purging treatments, and the reaction was carried out overnight at 25 °C under argon protection. After the reaction was completed, the mixture was quenched with water, extracted with dichloromethane, dried, concentrated, and purified by silica gel column chromatography (ethyl acetate / petroleum ether = 1:15) to give a yellow solid product in 92.1% yield.

[0031] Compound 3 1 H NMR, 13 The results of C NMR and mass spectrometry are as follows: Figures 5-6 As shown, it is clear that vinyl groups were successfully introduced into the triphenylamine backbone.

[0032] (2) Preparation of tin-lead perovskite precursor solution Formamidinium iodide (FAI), methylamine iodide (MAI), lead iodide (PbI2), and stannous iodide (SnI2) were added to a mixed solvent in a molar ratio of 0.7:0.3:0.5:0.5, wherein the mixed solvent was N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in a volume ratio of 3:1 to obtain a mixed solution with a concentration of 1.8 mol / L; then SnF2 with a molar amount of 10 mol% relative to SnI2 and TPA-OH additive prepared in step (1) were added to the mixed solution (the concentration of TPA-OH in the precursor solution was 0.8 mg / mL), and stirred at room temperature for 2 hours, and then filtered through a polytetrafluoroethylene filter membrane with a pore size of 0.22 μm to obtain a tin-lead perovskite precursor solution.

[0033] (3) Preparation of tin-lead perovskite thin films The ITO substrate was first cleaned and dried, then subjected to UV ozone treatment for 15 minutes, and then PEDOT:PSS was spin-coated on the substrate at 4000 rpm for 30 seconds. Finally, it was annealed at 150°C for 30 minutes to obtain an ITO substrate containing a hole transport layer.

[0034] The ITO substrate containing the hole transport layer was transferred to a nitrogen glove box, and 60 μL of the tin-lead perovskite precursor solution prepared in step (2) was dropped onto it. Then, a two-step spin coating method was used to form a film: the first step was spin coating at 1000 rpm for 10 s; the second step was spin coating at 4000 rpm for 40 s, and 200 μL of chlorobenzene was dropped as an anti-solvent when the second step was spin coated for 25 s; finally, it was annealed at 10 ℃ for 20 min to trigger the polymerization reaction of TPA-OH molecules to form the tin-lead perovskite film of this embodiment, denoted as w / TPA-OH.

[0035] Comparative Example 1 A method for preparing a tin-lead perovskite thin film includes the following steps: (1) Preparation of tin-lead perovskite precursor solution Formamidinium iodide (FAI), methylamine iodide (MAI), lead iodide (PbI2), and stannous iodide (SnI2) were added to a mixed solvent in a molar ratio of 0.7:0.3:0.5:0.5, wherein the mixed solvent was N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in a volume ratio of 3:1, to obtain a mixed solution with a concentration of 1.8 mol / L. Then, SnF2 with a molar amount relative to SnI2 was added to the mixed solution, and the mixture was stirred at room temperature for 2 hours. After that, the solution was filtered through a polytetrafluoroethylene filter membrane with a pore size of 0.22 μm to obtain a tin-lead perovskite precursor solution.

[0036] (2) Preparation of tin-lead perovskite thin films The preparation method was the same as in Example 1, and the tin-lead perovskite thin film of this comparative example was obtained, denoted as Control.

[0037] Application Example 1 A method for fabricating a perovskite solar cell device includes the following steps: The tin-lead perovskite thin film prepared in Example 1 was cooled to room temperature, and then 20 nm thick C layers were sequentially vacuum-deposited on its surface. 60 A perovskite solar cell device with a structure of ITO / PEDOT:PSS / tin-lead perovskite / C60 / BCP / Ag was fabricated using a 7nm BCP and a 100nm Ag electrode.

[0038] Comparative Application Example 1 The difference between Comparative Example 1 and Comparative Example 2 is that the tin-lead perovskite film prepared in Example 1 is replaced with the tin-lead perovskite film prepared in Comparative Example 1.

[0039] Performance testing 1. Microstructure The tin-lead perovskite films prepared in Example 1 and Comparative Example 1 were observed using a Hitachi SU8010 field emission scanning electron microscope. The results are as follows: Figure 1 As shown. By Figure 1 It can be seen that the surface of the film treated with TPA-OH (b) is more uniform than that of the untreated film (a), indicating that TPA-OH significantly improves the compactness of the grain boundaries.

[0040] The crystal structures of the tin-lead perovskite films prepared in Example 1 and Comparative Example 1 were characterized using a D8 Advance X-ray diffractometer, and the results are as follows: Figure 2 As shown, the horizontal axis 2Theta represents the 2θ diffraction angle, and the vertical axis Intensity represents the intensity of the diffraction peak. (From...) Figure 2 It can be seen that the TPA-OH additive did not change the main perovskite crystal phase structure.

[0041] 2. Inhibit Sn 2+ Oxidation performance Using Thermo Fisher ESCALAB Xi + X-ray photoelectron spectroscopy was used to analyze the chemical states of the tin-lead perovskite films prepared in Example 1 and Comparative Example 1. All spectra were calibrated using C 1s (284.8 eV) as the energy reference. The results are as follows: Figure 3 As shown in the figure. XPS shows that the Sn of the TPA-OH modified tin-lead perovskite film (b) is significantly different from that of the unmodified film (a). 4+ The proportion decreased from 6.05% to 3.82%, indicating that TPA-OH has the effect of inhibiting Sn. 2+The ability to oxidize.

[0042] 3. Photovoltaic performance Using a Keithley 2400 source meter, the current density-voltage (JV) characteristics of the photovoltaic devices prepared in Application Example 1 and Comparative Application 1 were tested under standard AM 1.5G illumination conditions (100 mW / cm²). The scanning methods included forward scanning (-0.1V to 0.9V) and reverse scanning (0.9V to -0.1V). The effective device area was 0.058 cm², defined by a metal shield. The results are as follows: Figure 10 As shown, the horizontal axis represents voltage, and the vertical axis represents current density. Figure 10 It can be seen that the photovoltaic device prepared in Application Example 1 has a significantly improved photovoltaic performance compared to the photovoltaic device prepared in Comparative Application Example 1.

[0043] 4. Stability The photovoltaic devices prepared in Example 1 and Comparative Application Example 1 were subjected to long-term storage tests under dark conditions in an unencapsulated N2 glovebox at 25°C. The results are as follows: Figure 11 As shown, the horizontal axis "Time" represents time, and the vertical axis "Normalized PCE" represents the standard photoelectric conversion efficiency. Figure 11 It can be seen that, compared with the photovoltaic device prepared in Application Example 1, the photoelectric conversion efficiency dropped to 50.12% of the initial value after 2400 hours of storage, while the photovoltaic device prepared in Application Example 1 after TPA-OH modification still maintained the initial efficiency of 81.47% after 3600 hours of storage, showing excellent stability.

[0044] For those skilled in the art, several simple deductions or substitutions can be made without departing from the inventive concept, without requiring creative effort. Therefore, any simple improvements made to this invention by those skilled in the art based on the disclosure of this invention should be within the scope of protection of this invention. The above embodiments are preferred embodiments of this invention, and all processes similar to this invention and equivalent changes should fall within the scope of protection of this invention.

Claims

1. A tin-lead perovskite thin film, characterized in that, The raw materials for preparing the tin-lead perovskite thin film include a tin-lead perovskite precursor solution, which contains a TPA-OH additive. The chemical structure of the TPA-OH additive is shown in formula (1). （1）。 2. The tin-lead perovskite thin film according to claim 1, characterized in that, The concentration of the TPA-OH additive in the tin-lead perovskite precursor solution is 0.1-5 mg / mL.

3. The tin-lead perovskite thin film according to claim 1, characterized in that, The tin-lead perovskite film contains tin-lead halide perovskite, and the general chemical formula of the tin-lead mixed halide perovskite is: FA 1-x MA x Pb 1-y Sn y X3; where: FA represents formamidinium, MA represents methylamine, and X represents halogen; the ranges of x and y are respectively: 0 <x≤0.5,0<y≤0.8。 4. The tin-lead perovskite thin film according to claim 3, characterized in that, X is selected from I and / or Br.

5. The tin-lead perovskite thin film according to claim 3, characterized in that, The ranges of x and y are 0.2≤x≤0.4 and 0.4≤y≤0.6, respectively.

6. A method for preparing a tin-lead perovskite thin film as described in any one of claims 1-5, characterized in that, Includes the following steps: A solution of tin-lead perovskite precursor containing TPA-OH additive is coated onto a substrate, and then annealed to allow the TPA-OH additive to undergo a polymerization reaction, thereby obtaining the tin-lead perovskite film.

7. The method for preparing a tin-lead perovskite thin film according to claim 6, characterized in that, The coating method is a two-step spin coating method, wherein: the first step is to spin coat at a speed of 800-1200 rpm for 8-12 seconds, the second step is to spin coat at a speed of 3500-4500 rpm for 35-45 seconds, and at 20-30 seconds of the second step, chlorobenzene anti-solvent is added dropwise.

8. The method for preparing a tin-lead perovskite thin film according to claim 6, characterized in that, The annealing temperature is 80-120℃, and the annealing time is 15-25 minutes.

9. The method for preparing a tin-lead perovskite thin film according to claim 6, characterized in that, The preparation process of the tin-lead perovskite precursor solution includes the following steps: taking FAX, MAX, PbX2 and SnX2 according to the stoichiometric ratio in the general chemical formula, dissolving them in an organic solvent; adding TPA-OH additive, mixing, and obtaining the solution.

10. A photovoltaic device, characterized in that, Includes the tin-lead perovskite thin film according to any one of claims 1-5.

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