Large-area perovskite thin film based on stress regulation and application thereof

Abstract

The invention discloses a large-area perovskite thin film based on stress regulation and control and application thereof. The large-area perovskite thin film is prepared by adding a stress regulation and control agent into a perovskite precursor solution and then coating the perovskite precursor solution by adopting a slit coating process, the chemical structure of the stress regulating agent is A-B-A, A is a passivation structural unit with a large molecular structure, B is a group VI A element, A and B are connected through a covalent bond, and the distance between coordination sites at two ends of the stress regulating agent is equal to a unit cell unit of a perovskite crystal. According to the invention, thermal stress generated by annealing in thin film preparation is improved by adding the regulating agent into the perovskite precursor solution, and mechanical stress generated by a slit coating tool bit is eliminated, so that the efficiency and the stability of the perovskite solar cell module are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cells, and in particular relates to a large-area perovskite film based on stress regulation and its application. Background Art

[0002] Perovskite solar cells have attracted wide attention due to their advantages such as high efficiency, low cost and adjustable energy band. At present, the efficiency of a small area in the laboratory has exceeded 26%, accelerating the process of industrialization. At present, the large-scale industrial preparation of perovskite is mainly based on two forms: slit coating and scraping. The mechanical stress caused by the blade and the thermal stress caused by annealing cause residual tensile stress in the prepared perovskite film, which is unfavorable to the performance of the component. There are many methods for regulating the tensile stress of perovskite films in the prior art, such as: using an anti-solvent containing a chemical cross-linking agent (CN113285031A), adding sulfone additives to the precursor solution (CN116406212A), post-treatment of the A-site cation replacement solution (CN116471902A) and adding a polymer buffer layer (CN114141954A).

[0003] However, the above technologies are mainly focused on small areas in the laboratory. For example, the anti-solvent and replacement liquid have too high requirements on the difficulty of experimental operation and are not suitable for the preparation of large-area films. Adding a buffer layer will increase the process steps of component preparation, thereby increasing the preparation cost. Sulfone additives mainly act on the surface of perovskite films, which can have a good effect on a small area, but the effect is not ideal on a large area and will affect the interface transmission between components and reduce component performance.

[0004] Therefore, the present invention designs a simple and efficient stress improvement method for large-area perovskite solar cell modules prepared by slit coating. Summary of the invention

[0005] One of the purposes of the present invention is to provide a large-area perovskite film, which is prepared by adding a stress regulator to a perovskite precursor solution and then coating the perovskite precursor solution using a slit coating process;

[0006] The chemical structure of the stress regulator is ABA, A is a passivation structural unit with a larger molecular structure, B is a VI A group element, A and B are connected by a covalent bond, and the spacing between the coordination sites at both ends of the stress regulator is equal to a unit cell unit of the perovskite crystal.

[0007] Furthermore, A is imidazole, pyridine or an organic ammonium salt, and B is O or S.

[0008] In the embodiment of the present invention, the stress regulator used has the following structural formula:

[0009]

[0010] In an embodiment of the present invention, a stress regulator 1,1'-carbonylbis(3-methyl-1H-pyridin-3-ium) is added to a perovskite precursor FAPbI3 solution at a concentration of 0.3 mmol / ml to obtain a perovskite film, which is then used to prepare a solar cell module.

[0011] A second object of the present invention is to provide an application of the above-mentioned large-area perovskite film in the preparation of perovskite solar cells.

[0012] The third object of the present invention is to provide a perovskite solar cell, comprising a transparent conductive substrate, a hole transport layer, a perovskite light absorbing layer, an electron transport layer and a metal electrode arranged in sequence along the incident direction of sunlight, wherein the perovskite light absorbing layer is the above-mentioned large-area perovskite film.

[0013] The present invention designs a molecule with an ABA structure, where B is a VI A group element (O, S, etc.), and A is a passivation structural unit with a larger molecular structure (imidazole, pyridine, organic ammonium salt, etc.). At the same time, the spacing between the coordination sites at both ends of the molecule is just equal to a unit cell unit of the perovskite crystal. Since this series of molecules can anchor a single lattice of perovskite, the tensile stress generated during the preparation of the perovskite film can be alleviated, and the VI A group element can coordinate with free lead iodide to reduce the defects of the perovskite film and further improve the performance of the component.

[0014] This series of molecules is added to the perovskite precursor solution, and a large-area perovskite battery module is prepared using a slit coating process. Since this series of molecules acts on a single lattice, its effect is basically not affected by the size of the area, making it more suitable for use in large-area modules. At the same time, its stress relief effect can not only reduce the tensile stress caused by film annealing, but also reduce the mechanical stress caused by large blade equipment.

[0015] The present invention provides a simple and efficient stress improvement method for large-area perovskite solar cell modules prepared by slit coating. This method uses an ABA-type molecule as an additive to add to the perovskite precursor solution by anchoring a single perovskite crystal. Experiments have found that such molecules can not only improve the thermal stress generated by film preparation annealing, but also eliminate the mechanical stress generated by the slit coating blade, ultimately improving the efficiency and stability of the perovskite solar cell module. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The efficiency comparison results of the standard chip component and the experimental group component in Example 1 are shown. DETAILED DESCRIPTION

[0017] The preferred embodiments of the present invention will be described in detail below in conjunction with examples. It should be understood that the following examples are provided only for the purpose of illustration and are not intended to limit the scope of the present invention. Those skilled in the art may make various modifications and substitutions to the present invention without departing from the purpose and spirit of the present invention.

[0018] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0019] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0020] Example 1

[0021] Step 1: Preparation of ABA, taking 1,1'-carbonylbis(3-methyl-1H-pyridin-3-ium) as an example, 1,1'-thiocarbonyldipyridine (1.62 g, 10 mmol) was added to 10 mL of ethanol, placed in a round-bottom flask, and cooled in an ice bath. 4 mL of HI solution (57%, ~30 mmol of HI) was added dropwise under magnetic stirring. The mixture was then allowed to react for 2 hours and then slowly heated to 60°C. After the reaction was completed, the mixture was evaporated using a rotary evaporator, and the residue was stirred in ether for 10 minutes and filtered. The crude product was washed three times with 5 mL of ether. The washed solid was redissolved in ethanol and recrystallized after adding ether. The recrystallized solid was filtered and washed three times with ether. After drying in a vacuum oven at room temperature for 24 hours, the product was obtained.

[0022] Step 2: Prepare the substrate: deposit a transparent electrode FTO (fluorine-doped SnO2 conductive glass) on the surface of a transparent substrate (conductive glass substrate), and the transparent substrate and the transparent electrode constitute the substrate of the composite hole transport layer; wash the substrate with deionized water, ethanol, acetone, isopropanol, and ethanol respectively, blow dry the substrate with nitrogen, and then treat the substrate with UV ozone for 15 minutes.

[0023] Step 3: Prepare a composite hole transport layer and deposit a NiOx hole transport layer using ALD (atomic deposition technology).

[0024] Step 4: Prepare a perovskite active layer: dissolve lead iodide and methyl ether ammonium iodide in a molar ratio of 1:1 in a mixed solvent of dimethyl sulfoxide and dimethylformamide, wherein the volume ratio of dimethylformamide to the dimethyl sulfoxide is 7:3; at the same time, stir at 60°C for 12 hours under the protection of an inert gas to obtain a perovskite precursor FAPbI3 solution; add the above-prepared 1,1'-carbonyldi(3-methyl-1H-pyridin-3-ium) additive to the configured perovskite precursor solution at a concentration of 0.3mmol / ml as an experimental group, and the blank group (standard piece) without the addition of the additive; apply the obtained perovskite precursor solution to the composite hole transport layer at room temperature through a slit coater at a coating rate of 30mm / s. After coating, quickly place it in a vacuum press to evacuate, then anneal on a hot plate at 130°C for 10min, and then anneal in an annealing furnace for 10min to obtain the perovskite active layer.

[0025] Step 5: Prepare electron transport layer: prepare C60 by thermal evaporation and prepare SnO2 electron transport layer by ALD.

[0026] Step 6: Prepare the counter electrode: Under vacuum conditions, evaporate copper with a thickness of 80 nm on the hole blocking layer as the counter electrode to obtain a perovskite solar cell module with an area of ​​30*40 cm.

[0027] The prepared perovskite solar cell module was tested, and the results are as follows:

[0028] Pmax Isc Voc FF Eff Label 14.34 0.52 45.15 0.61 16.06 Experimental Group 17.67 0.54 45.65 0.71 19.72

[0029] From the above results, it can be seen that after adding additives, the morphology of the perovskite film is significantly improved during the preparation of perovskite battery components, and the stress is eliminated, resulting in a significant improvement in the open circuit voltage and efficiency of the experimental group components.

Claims

1. A large-area perovskite film, characterized in that: The large-area perovskite film is prepared by adding a stress regulator to a perovskite precursor solution and then coating the perovskite precursor solution using a slit coating process; The chemical structure of the stress regulator is ABA, A is a passivation structural unit with a larger molecular structure, B is a VIA group element, A and B are connected by a covalent bond, and the spacing between the coordination sites at both ends of the stress regulator is equal to a unit cell unit of the perovskite crystal.

2. The large-area perovskite film according to claim 1, characterized in that: The A is imidazole, pyridine or an organic ammonium salt, and the B is O or S.

3. The large-area perovskite film according to claim 2, characterized in that: The stress regulator structural formula is as follows:

4. Use of the large-area perovskite film according to any one of claims 1 to 3 in the preparation of perovskite solar cells.

5. A perovskite solar cell, characterized in that: It comprises a transparent conductive substrate, a hole transport layer, a perovskite light absorbing layer, an electron transport layer and a metal electrode arranged in sequence along the incident direction of sunlight, wherein the perovskite light absorbing layer is the large-area perovskite film described in any one of claims 1 to 3.

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