Perovskite solar cell containing protective layer and preparation method thereof

Abstract

The invention relates to the technical field of solar cells, in particular to a perovskite solar cell containing a protective layer and a preparation method of the perovskite solar cell. The solar cell sequentially comprises a conductive substrate, a charge transport layer 1, a perovskite light absorption layer, a charge transport layer 2, a thin film electrode and a protective layer from bottom to top, and the protective layer is one or more of a poly-p-xylylene film, a polyimide film, a polyamide film, a polystyrene film, a polypropylene film and a silicon dioxide film. According to the method disclosed by the invention, a protective layer is constructed on the surface of the battery through a chemical vapor deposition process, and the prepared film has excellent mechanical property, thermal stability, chemical stability, chemical corrosion resistance, high water vapor barrier property, high oxidation resistance and good hydrophobic property. According to the method, the perovskite solar cell packaging technology is promoted to be evolved towards the ultrathin, intelligent and low-cost directions, and the application range of the perovskite solar cell packaging technology is further widened.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and more particularly to a perovskite solar cell with a protective layer and its preparation method. Background Technology

[0002] Converting solar energy into electricity, i.e., photovoltaic power generation, has become an important way to utilize renewable energy globally. The most crucial component of a photovoltaic power generation system is the solar cell, which captures solar photons and performs photoelectric conversion. Perovskite solar cells have attracted widespread attention due to their excellent photoelectric properties, abundant raw materials, simple fabrication process, and low-carbon, environmentally friendly manufacturing process. Recent research has focused on further improving the stability of perovskite solar cells and the photoelectric conversion efficiency of large-area perovskite solar cells, exploring more diverse thin-film fabrication methods. However, the lifespan of perovskite solar cells is significantly affected by factors such as the easy decomposition of organic-inorganic hybrid perovskite semiconductor materials upon contact with water and the ion escape from within the perovskite layer corroding the metal electrodes. Currently, ethylene is widely used for encapsulation of perovskite solar cells. Vinyl acetate copolymer (EVA) is used, but substances such as acetic acid produced during long-term use of EVA film can easily react with perovskite. The degradation of small molecules such as acetic acid can lead to a decrease in the transparency of the material, and the high-temperature lamination process has a certain impact on perovskite. This poses a more severe challenge to encapsulation materials.

[0003] Effective packaging technologies can solve these problems, therefore developing simple and low-cost packaging solutions is key to the industrialization of perovskite photovoltaics. Summary of the Invention

[0004] The purpose of this invention is to provide a perovskite solar cell with a protective layer and its preparation method. Based on the characteristics of existing perovskite cell encapsulation processes being complex and high-temperature lamination encapsulation affecting the perovskite lifespan, this invention uses chemical vapor deposition to prepare a protective layer on the surface of the perovskite solar cell. The resulting film has a suitable thickness, good light transmittance, and can effectively improve the photoelectric conversion efficiency of the cell and suppress ion diffusion between the electrode and the perovskite.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: The present invention provides a perovskite solar cell with a protective layer, the solar cell comprising a conductive substrate, a charge transport layer 1, a perovskite light-absorbing layer, a charge transport layer 2, a thin film electrode, and a protective layer; The protective layer is one or more of the following: parylene film, polyimide film, polyamide film, polystyrene film, polypropylene film, and silica film.

[0006] In the above technical solution, further, when the charge transport layer 1 is a hole transport layer, the charge transport layer 2 is an electron transport layer; when the charge transport layer 1 is an electron transport layer, the charge transport layer 2 is a hole transport layer.

[0007] In the above technical solution, further, the conductive substrate is a conductive glass, a stainless-steel foil, or a polymer covered with a metal film.

[0008] In the above technical solution, further, the conductive glass is composed of a glass substrate and a transparent conductive film, and the transparent conductive film is one or more of fluorine-doped tin oxide (FTO), indium tin oxide (ITO), doped zinc oxide (AZO, BZO, GZO, AGZO); the thickness of the transparent conductive film is 100 - 200 nm.

[0009] In the above technical solution, further, the hole transport layer is NiO x , with a thickness of 1 - 100 nm.

[0010] In the above technical solution, further, the electron transport layer is one or more of fullerenes and their derivatives, bathocuproine (BCP), zinc oxide, and tin oxide, with a thickness of 10 - 200 nm.

[0011] In the above technical solution, further, the thin-film electrode layer is one or more of a metal film and a conductive metal oxide; the metal film includes aluminum, nickel, chromium, silver, copper, or gold, and the conductive metal oxide includes ITO, FTO, or AZO; the thickness of the thin-film electrode layer is 100 - 300 nm.

[0012] In the above technical solution, further, the perovskite precursor in the perovskite light-absorbing layer is Cs x MA y FA z Pb(I a Br 1-a )3, where 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, 0 ≤ z ≤ 1, x + y + z = 1, 0 < a ≤ 1; or in Cs x MA y FA z Pb(I a Br 1-a )3, part of Cs, MA, or FA is replaced by an alkali metal or one of alkali metals with a weight content less than 10% in each; the thickness of the perovskite light-absorbing layer is 200 - 600 nm.

[0013] Another aspect of the present invention provides a method for preparing the above-mentioned perovskite solar cell with a protective layer, comprising sequentially preparing a charge transport layer 1, a perovskite light-absorbing layer, a charge transport layer 2, a thin film electrode and a protective layer on a conductive substrate, wherein the method for preparing the protective layer is one of atmospheric pressure chemical vapor deposition, low pressure chemical vapor deposition, plasma-enhanced chemical vapor deposition and atomic layer deposition.

[0014] In the above technical solution, the vacuum degree of the atmospheric pressure chemical vapor deposition is further 10. 5 Pa; The vacuum level of the low-pressure chemical vapor deposition is 0.1-1000 Pa; The vacuum degree of the plasma-enhanced chemical vapor deposition is 10-500 Pa; The vacuum level of the atomic layer deposition is >10 Pa.

[0015] In the above technical solution, the fabrication method of the perovskite solar cell specifically includes the following steps: (1) Clean the conductive substrate; (2) Using magnetron sputtering, the chamber is evacuated to a vacuum level of less than 2.0 × 10⁻⁶. -4 Pa, a charge transport layer 1 was prepared on a conductive substrate by introducing a mixed gas of Ar and O2 at 12 sccm (the volume ratio of Ar and O2 was 95:5) and O2 at 8 sccm. (3) Using the scraping method, the perovskite precursor solution is scraped onto the charge transport layer 1, and after annealing, a perovskite light-absorbing layer is formed. The concentration of the perovskite precursor solution is 0.6-1.5M, the annealing temperature is 70-350 ℃, and the annealing time is 1-1000min. (4) A charge transport layer 2 is prepared on the perovskite light-absorbing layer using a blade coating method or a vapor deposition method; (5) Thin film electrodes are prepared on charge transport layer 2 by magnetron sputtering or vapor deposition to obtain perovskite solar cells; (6) Prepare a protective layer on the surface of perovskite solar cells using atmospheric pressure chemical vapor deposition, low pressure chemical vapor deposition, plasma-enhanced chemical vapor deposition or atomic layer deposition.

[0016] In step (6), the corresponding precursor is selected. The precursor of parylene film is a dimer of xylene, such as di-p-xylene; the precursor of polyimide film is a mixture of aromatic diamine and aromatic dianhydride; the precursor of polyamide film is a mixture of aromatic diamine and aromatic dicarboxylic acid; the precursor of polystyrene film is styrene monomer; the precursor of polypropylene film is propylene monomer; and the precursor of silicon dioxide is single crystal silicon.

[0017] The beneficial effects of this invention are as follows: 1. This invention provides a simple packaging technology for perovskite solar cells, which effectively blocks external water and oxygen invasion, suppresses ion diffusion between electrodes and metals, and ultimately effectively improves device stability.

[0018] 2. This invention employs chemical vapor deposition (CVD) to prepare a protective layer, reducing the destructive effects of water vapor and oxygen in the air on perovskite solar cells. It effectively isolates water and oxygen and inhibits ion escape. CVD technology deposits a uniform and highly crystalline thin film by evaporating precursor materials under vacuum conditions. Because this technology uses a solvent-free process, it avoids solvent-induced instability, thus demonstrating molecular-level fine control over film thickness during the preparation of high-quality films. With advancements in materials science and equipment technology, CVD is expected to become one of the main methods for large-scale production of perovskite solar cells.

[0019] 3. In practical applications, the protective film prepared by chemical vapor deposition has a moderate thickness, which can effectively increase the short-circuit current density (Jsc) of perovskite solar cells. Moreover, the preparation method is simpler, suitable for large-area mass production, and has a lower cost.

[0020] 4. The protective layer of the perovskite solar cell of the present invention has excellent mechanical properties, thermal stability, chemical stability, chemical corrosion resistance, water and oxygen corrosion barrier, and mechanical properties, achieving comprehensive improvement. Different protective layers can be flexibly selected for encapsulation according to the actual application scenario of the battery.

[0021] 5. Using the perovskite solar cell of the present invention, since the thickness of the protective layer can be better controlled, a multi-layer structure can be used for encapsulation. Through the synergistic effect of different functional materials, all-round improvement can be achieved in terms of barrier properties, mechanical strength, photoelectric efficiency and environmental adaptability. Multi-layer encapsulation can develop towards ultra-thinness, intelligence and low cost, further expanding the application boundaries of perovskite solar cells. Attached Figure Description

[0022] Figure 1 The water contact angle of the perovskite solar cell without a protective layer in Example 1; Figure 2 The water contact angle of the perovskite solar cell with a protective layer in Example 1; Figure 3 The water contact angle of the perovskite solar cell with a protective layer in Example 2; Figure 4 The water contact angle of the perovskite solar cell with a protective layer in Example 3; Figure 5 The water contact angle of the perovskite solar cell with a protective layer in Example 4; Figure 6This is a schematic diagram of the perovskite solar cell structure with a protective layer according to the present invention. Detailed Implementation

[0023] The implementation method and detailed operation of the present invention are described in detail below with reference to the embodiments and accompanying drawings. However, the present invention is not limited to the embodiments described below, and all methods falling within the scope of the claims should be protected by the present invention.

[0024] Example 1 1) Cleaning the conductive substrate: Clean the conductive substrate with alkaline solution and deionized water and dry it for later use. 2) Preparation of ITO transparent conductive film: Using magnetron sputtering, the cleaned conductive substrate is placed in the chamber, and the chamber is evacuated to a vacuum level of less than 2.0 × 10⁻⁶. -4 Pa, 20 sccm of Ar and O2 mixed gas (Ar and O2 volume ratio of 95:5), power 200 W, working gas pressure 5 mTorr, rotation speed 0.4 rpm, sputtering ITO transparent conductive film on the surface of conductive substrate; 3) Preparation of NiO x Hole transport layer: Using magnetron sputtering, the conductive substrate / ITO obtained in step (2) is placed into the chamber, and the chamber is evacuated to a vacuum level of less than 2.0 × 10⁻⁶. -4 Pa, with 12 sccm of Ar and -O2 mixture (Ar to O2 volume ratio 95:5) and 8 sccm of O2 introduced, power 140W, working pressure 2mTorr, rotation speed 0.4 rpm, sputtering hole transport layer, NiO x After the layer is prepared, the substrate is annealed and crystallized at 300℃ for 1 hour, and then naturally cooled. 4) Coating a perovskite light-absorbing layer: On NiO x Perovskite precursor solution (FAI, PbI, CSBr, DMF, NMP, 2-ME, concentration 1M) was coated onto the surface of the hole transport layer by scraping with a slit of 200 μm, a travel speed of 0.3 m / min, and a feed rate of 250 rpm. Extraction was performed using an air knife with a pressure of 0.8 MPa. The completed sample was then annealed at 110 °C for 30 min. 5) Fabrication of the electron transport layer: After the above steps, a conductive substrate / ITO / NiO is obtained. x For the / PVK sample, PCBM was coated on the sample surface with a slit width of 150μm, a travel speed of 0.4m / min, a feed rate of 150rpm, and an air knife pressure of 0.1MPa. The same process was used to coat the PCBM surface with a 2.5 wt% zinc oxide nanoparticle isopropanol dispersion. After coating, the sample was annealed at 100℃ for 10 min. 6) Preparation of ITO electrode: The sample prepared according to the above steps is placed in a magnetron sputtering system to sputter a 200 nm ITO transparent electrode. The back vacuum is 20 mTorr, the power is 180 W, the rotation speed is 0.2 rpm, the working pressure is 5 mTorr, and a mixture of Ar and O2 gas (volume ratio of Ar to O2 is 95:5) is introduced to obtain a perovskite solar cell. 7) Preparation of protective layer: Xylene is selected as the precursor. Xylene powder is weighed and placed in the blood of the sublimation chamber. The vacuum environment is maintained and the pressure is controlled at 1 Pa. The sublimation chamber is heated and the temperature is controlled at 90-200℃. The gaseous dimer vapor is pumped by the vacuum system and passed through the high-temperature pyrolysis furnace tube at 600-700℃. Under the high-temperature reaction, the C-C bond connecting the two benzene rings in the dimer molecule breaks and decomposes into two active monomer molecules. The active monomer vapor flows out of the pyrolysis furnace and enters the deposition chamber. The deposition chamber temperature is maintained at 25℃. The monomer active molecules diffuse to the battery surface and are adsorbed. When the two monomers meet, the free radicals react to form covalent bonds. The polymerization reaction occurs on the battery surface and grows in an ordered manner to form a highly uniform, non-porous, and transparent parylene film with a thickness of 100 nm.

[0025] The perovskite solar cell prepared in Example 1 and the perovskite solar cell with a protective layer (cell area: 14cm × 14cm) were placed on a test stage and tested under standard light intensity. The test voltage was 2.5V. The cell performance is shown in Table 1.

[0026] Table 1

[0027] Example 2 The protective layer preparation method in Example 1 was changed from parylene film to polyimide film. The specific preparation process is as follows: the battery was placed on the sample holder to ensure good thermal contact, the chamber was closed and the vacuum pump sequence was started to evacuate the base vacuum to <5.0×10⁻⁶. -6 To eliminate water vapor and oxygen contamination, the sample stage was heated to 250°C, and Ar gas was introduced until the working pressure stabilized at 50 mTorr. Organic precursors containing benzene rings and nitrogen-containing precursors were introduced in gaseous form: toluene (Ar carrier gas) at 10 sccm and ammonia at 10 sccm were pre-flowed for several tens of seconds to homogenize the atmosphere. Radio frequency power (50W) was applied to generate plasma. High-energy electrons in the plasma bombarded the precursor molecules, causing them to decompose and ionize, generating a large number of active free radicals and ions. These active groups underwent gas-phase polymerization and cross-linking reactions on the substrate surface at room temperature or under heating, forming a polyimide film. The remaining operating conditions were the same as in Example 1.

[0028] The perovskite solar cell prepared in Example 2 and the perovskite solar cell with a protective layer (cell area: 14cm × 14cm) were placed on a test stage and tested under standard light intensity. The test voltage was 2.5V. The cell performance is shown in Table 2.

[0029] Table 2

[0030] Example 3 The protective layer preparation method in Example 1 was changed from parylene film to silicon dioxide film. The specific preparation process is as follows: The silicon wafer was placed in a quartz boat and slowly placed into the isothermal zone of the reaction tube. The reaction chamber was evacuated to below 10 mTorr. The multi-temperature zone furnace was turned on at 680-720°C. While continuously evacuating, a certain amount of nitrogen gas was introduced into the reaction chamber to stabilize the process pressure at 200 mTorr. The valve leading to the TEOS bubbler was opened, and high-purity N2 was used as the carrier gas and introduced into the TEOS liquid, which was maintained at a constant temperature of 35°C, at a set flow rate. The N2 carried its saturated vapor into the reaction chamber. The TEOS vapor underwent thermal decomposition and oxidation on the high-temperature silicon wafer surface, generating SiO2, which was then deposited to form a polyamide film on the battery surface. The remaining operating conditions were the same as in Example 1.

[0031] The perovskite solar cell prepared in Example 3 and the perovskite solar cell with a protective layer (cell area: 14cm × 14cm) were placed on a test stage and tested under standard light intensity. The test voltage was 2.5V. The cell performance is shown in Table 3.

[0032] Table 3

[0033] Example 4 The protective layer preparation method in Example 1 was changed from parylene film to polypropylene film. The specific preparation process is as follows: The polypropylene film is prepared by atomic layer deposition (ALD) technology. The battery is placed in the ALD reaction chamber, the reaction chamber is evacuated to <10 Pa, and the substrate is preheated to 250°C. Propylene monomer + tert-butyl peroxide is selected as the precursor. Carrier gas (Ar) is introduced into the bubble bottle of the liquid precursor, carrying propylene monomer vapor into the reaction chamber, ensuring that the propylene monomer vapor covers the substrate. Nitrogen gas is used to purge for 30 seconds to remove unreacted propylene monomer and byproducts. Carrier gas (Ar) is introduced into the bubble bottle of the liquid precursor, carrying tert-butyl peroxide vapor into the reaction chamber, ensuring that the tert-butyl peroxide reacts completely with the propylene monomer. Nitrogen gas is used to purge for 30 seconds. The above steps are repeated until the polypropylene film reaches the preset thickness. The remaining operating conditions are the same as in Example 1.

[0034] The perovskite solar cell prepared in Example 4 and the perovskite solar cell with a protective layer (cell area: 14cm × 14cm) were placed on a test stage and tested under standard light intensity. The test voltage was 2.5V. The cell performance is shown in Table 4.

[0035] Table 4

[0036] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the implementation. The scope of protection of the present invention should be determined by the scope defined in the claims. Other variations or modifications can be made based on the above description. Obvious variations or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A perovskite solar cell with a protective layer, characterized in that: The solar cell comprises, from bottom to top, a conductive substrate, a charge transport layer 1, a perovskite light-absorbing layer, a charge transport layer 2, a thin film electrode and a protective layer. The protective layer is one or more of parylene film, polyimide film, polyamide film, polystyrene film, polypropylene film and silicon dioxide film. 2.The perovskite solar cell with a protective layer according to claim 1, characterized in that, The thickness of the protective layer is 1-200 nm. 3.The perovskite solar cell with a protective layer according to claim 1, characterized in that, When the charge transport layer 1 is a hole transport layer, the charge transport layer 2 is an electron transport layer; when the charge transport layer 1 is an electron transport layer, the charge transport layer 2 is a hole transport layer. 4.The perovskite solar cell with a protective layer according to claim 1, characterized in that, The conductive substrate is a conductive glass, a stainless steel foil or a polymer covered with a metal film.

5. The protected perovskite solar cell according to claim 4, characterized in that, The conductive glass comprises a glass substrate and a transparent conductive film, and the transparent conductive film is one or more of fluorine-doped tin oxide, indium tin oxide and doped zinc oxide. 6.The perovskite solar cell with a protective layer according to claim 3, characterized in that, The hole transport layer is NiO x The electron transport layer is one or more of fullerene and derivatives thereof, bathocuproine, zinc oxide, tin oxide. 7.The protective layer containing perovskite solar cell according to claim 1, wherein, The thin film electrode layer is one or more of a metal film and a conductive metal oxide. 8.The protective layer-containing perovskite solar cell according to claim 1, characterized in that, The perovskite precursor in the perovskite light-absorbing layer is Cs x MA y FA z Pb(I a Br 1-a )3, wherein 0≤x≤1, 0≤y≤1, 0≤z≤1, x+y+z=1, 0<a≤1; or Cs x MA y FA z Pb(I a Br 1-a )3, wherein part of Cs, MA or FA is replaced by less than 10% of alkali metal or one of the alkali metals by weight.

9. A method of producing a perovskite solar cell with a protective layer according to any one of claims 1 to 8, characterized in that, The method comprises sequentially preparing a charge transport layer 1, a perovskite light-absorbing layer, a charge transport layer 2, a thin film electrode and a protective layer on a conductive substrate, wherein the preparation method of the protective layer is one of atmospheric pressure chemical vapor deposition, low pressure chemical vapor deposition, plasma enhanced chemical vapor deposition and atomic layer deposition.

10. The method of claim 9, wherein, The vacuum degree of the atmospheric pressure chemical vapor deposition is 10 5 Pa; The vacuum degree of the low pressure chemical vapor deposition is 0.1-1000 Pa. The vacuum degree of the plasma enhanced chemical vapor deposition is 10-500 Pa. The vacuum degree of the atomic layer deposition is >10 Pa.

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