Preparation method of perovskite solar cell protection layer

Abstract

The invention belongs to the field of solar cells, and particularly relates to a preparation method of a perovskite solar cell protection layer. The perovskite solar cell comprises a conductive substrate, a charge transport layer 1, a perovskite light absorption layer, a charge transport layer 2 and a thin film electrode which are stacked in sequence, and protective layers are prepared on the surface and the peripheral edge of the perovskite solar cell by adopting a spraying method. By controlling spraying parameters, the thickness and uniformity of the thin film can be accurately controlled, the microstructure of the thin film can be effectively regulated and controlled, pinhole defects are reduced, water and oxygen invasion is effectively isolated, the preparation method has high flexibility, and a protective layer can cover the top and the edge of the whole battery; and meanwhile, a closed cover body is used in the spraying process, nitrogen is introduced into the closed cover body or negative pressure of the cover body is kept, leakage of the organic solvent is avoided, and a high-quality protective film can be obtained easily.

Description

Technical Field

[0001] This invention belongs to the field of solar cells, and particularly relates to a method for preparing a protective layer for a perovskite solar cell. Background Technology

[0002] Perovskite solar cells are considered a third-generation, novel concept in solar cells, renowned for their high photoelectric conversion efficiency, low cost, and flexible processing. They have experienced rapid development in recent years, with their photoelectric conversion efficiency gradually becoming comparable to silicon cells and approaching the levels required for industrial applications. However, the main challenge for the industrial application of perovskite solar cells is their stability. Good encapsulation is crucial for maintaining high efficiency over long periods, as it not only solves the stability problem but also extends the cell's lifespan.

[0003] In the development of perovskite solar cells, the preparation of large-area perovskite solar cells is an important step in the industrialization of perovskite solar cells. Among the many methods for preparing large-area thin films, the spraying method has the advantages of simple operation, low production cost, good uniformity of prepared films, and high solution utilization. Films prepared by the spraying method can be applied to various complex substrates and are easy to industrialize, thus occupying an important position in the field of thin film preparation. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a protective layer for perovskite solar cells. Based on the complexity of existing perovskite cell encapsulation processes and the impact of high-temperature lamination on perovskite cell lifespan, this invention designs and utilizes necessary equipment from the perovskite preparation process to prepare a protective layer on the surface of perovskite solar cells. A polymer protective film is prepared using a spraying method under a controlled atmosphere. This not only forms a uniform and dense polymer film on the surface of the perovskite cell, providing effective protection, but also optimizes the film's performance through precise control of process conditions.

[0005] This invention prepares a protective film by selecting ultrasonic spraying, electrostatic spraying, pneumatic spraying, thermal spraying, and other methods. This method is not only simple to operate and suitable for large-area battery production, but also produces a film with appropriate thickness and good light transmittance, which can effectively improve the energy conversion efficiency of the battery and suppress ion diffusion between the electrode and the perovskite. At the same time, by selecting suitable polymer materials, it can achieve low-temperature encapsulation while effectively preventing wind and sand, rain, water, moisture, and environmental damage. It can also effectively extend the service life of perovskite solar cells while solving the problem of complex encapsulation processes.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: This invention provides a method for preparing a protective layer for a perovskite solar cell. The perovskite solar cell includes a conductive substrate, a charge transport layer 1, a perovskite light-absorbing layer, a charge transport layer 2, and a thin-film electrode stacked sequentially. A protective layer is prepared on the surface and surrounding edges of the perovskite solar cell using a spraying method.

[0007] Furthermore, the spraying method includes one of ultrasonic spraying, electrostatic spraying, pneumatic spraying, and thermal spraying.

[0008] Furthermore, the preparation of the protective layer includes the following steps: Step 1: Cover the perovskite solar cell and spray gun with a sealed cover, introduce nitrogen into the sealed cover or maintain negative pressure in the cover, and spray the polymer material solution onto the surface and edges of the solar cell. Step 2: Anneal the device coated with polymer material.

[0009] Further, in step 1, the polymeric material includes one of polyethylene, polypropylene, polymethyl methacrylate (PMMA), polyvinyl butyral (PVB), and silicon-based polymers; the silicon-based polymer includes one of polydimethylsiloxane, silicon dioxide, and transparent silicon conformal coating materials (e.g., DOWSIL1-2577 silicon conformal coating material, DOWSIL1-2620 silicon conformal coating material).

[0010] Furthermore, in step 1, the concentration of the polymer material solution is 5-20 wt%.

[0011] Furthermore, in step 1, the diameter of the spray gun nozzle is 0.5-2.0 mm, the spraying pressure is controlled at 0.1-0.5 MPa, and the spraying distance is 10-30 cm.

[0012] Furthermore, in step 2, the annealing temperature is 100-130℃, and the annealing time is 10-30 minutes.

[0013] Furthermore, the conductive substrate is a conductive glass, stainless steel foil, or a polymer covered with a metal film; the conductive glass consists of a glass substrate and a transparent conductive film, wherein the transparent conductive film is one or more of fluorine-doped tin oxide (FTO), indium tin oxide (ITO), and zinc oxide doped (e.g., AZO, BZO, GZO, AGZO, etc.); the polymer covered with the metal film consists of a flexible substrate and a transparent conductive film, wherein the transparent conductive film is one or more of fluorine-doped tin oxide (FTO), indium tin oxide (ITO), and zinc oxide doped (e.g., AZO, BZO, GZO, AGZO).

[0014] 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.

[0015] Further, the hole transport layer is NiO X ; The electron transport layer is one or more of fullerene and its derivatives, bathocuproine, zinc oxide, and tin oxide.

[0016] 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; for example, when x = 1 and a = 1, the perovskite precursor is CsPbI3, when y = 1 and a = 1, the perovskite precursor is MAPbI3, when z = 1 and a = 1, the perovskite precursor is FAPbI3; 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% each; the alkali metals include lithium, sodium, potassium, rubidium, or francium; the alkaline earth metals include beryllium, magnesium, calcium, strontium, barium, or radium.

[0017] Further, the thin film electrode is one of aluminum, nickel, chromium, silver, copper, gold, ITO, FTO, and AZO.

[0018] Further, the preparation method of the perovskite solar cell includes the following steps: (1) Cleaning the conductive substrate; (2) Using magnetron sputtering to prepare an ITO functional layer on the conductive substrate; (3) Using magnetron sputtering to prepare a NiOx transport layer on the conductive substrate / ITO; (4) Using spray coating to spray the perovskite precursor solution on the conductive substrate / ITO / NiOx, and annealing to form a perovskite light-absorbing layer; (5) Using spray coating / vapor deposition to prepare PCBM / ZnO or C60 / BCP on the conductive substrate / ITO / NiOx / PVK to obtain an electron transport layer; (6) Using sputtering / vapor deposition to prepare an ITO transparent electrode and a metal electrode, thereby obtaining a perovskite solar cell.

[0019] In step (2), the chamber is evacuated to a vacuum level less than 2.0 × 10⁻⁶. -4 Pa, introduce 20 sccm of Ar / O2 mixed gas (Ar:O2=95:5), and after the vacuum in the chamber stabilizes, sputter ITO with a thickness of 100-200 nm.

[0020] In step (3), the chamber is evacuated to a vacuum level less than 2.0 × 10⁻⁶. -4 Pa, introduce 12 sccm of Ar / O2 mixed gas (Ar:O2=95:5) and 8 sccm of O2, and after the vacuum in the chamber is stable, sputter NiOx to prepare a hole transport layer with a thickness of 20-100 nm. In step (4), the concentration of the perovskite precursor is 0.6-1.5M, the annealing temperature of the perovskite layer is 70-350 ℃, the annealing time is 1-1000 min, and the thickness is 200-600nm. In step (5), the electron transport layer can be prepared by spraying using PCBM or ZnO, or by vapor deposition using C. 60 BCP, with a thickness of 10-200nm; In step (6), the thickness of the thin film electrode is 100-300 nm.

[0021] The beneficial effects of this invention are as follows: (1) This invention is based on a spray coating method to prepare a protective layer. A solution containing polymer materials is first atomized into tiny droplets, which are then sprayed at a certain speed onto the surface and edges of a pre-prepared perovskite solar cell device. When the droplets contact the device surface and edges, the solvent evaporates rapidly, while the solute gradually deposits and accumulates on the device surface and edges. As the spraying process continues, the solute continuously accumulates, eventually forming a continuous protective layer. The protective layer obtained by this invention has a uniform thickness and a smooth surface, effectively reducing light reflection and increasing the short-circuit current density (Jsc) of the perovskite solar cell.

[0022] (2) The protective layer preparation method of the present invention can effectively improve the solution utilization rate, which can reach more than 80%, effectively reduce production costs and reduce environmental pollution, and has significant economic benefits and environmental costs, which is of great significance for promoting the industrialization of perovskite solar cells.

[0023] (3) The present invention controls the atmosphere inside the shield or maintains a negative pressure inside the shield when preparing the protective layer. Preparing the protective layer in a nitrogen atmosphere can ensure that the perovskite absorber layer is not prematurely damaged in subsequent processes, laying the foundation for obtaining high-quality and stable devices; secondly, in a nitrogen environment, the perovskite surface can remain clean and dry, allowing the subsequently deposited protective layer to form a tighter heterogeneous contact with the battery with fewer defects, thereby reducing interfacial recombination. This provides an ideal environment for the preparation of polymer protective film, which is beneficial to improving the quality and protective performance of the film, thereby enhancing the stability of perovskite solar cells. Under a negative pressure inside the shield, the polymer material solution is sprayed from the spray gun nozzle to form droplets. When the spraying interior is in a negative pressure environment, the gas pressure around the droplets is low during the transport process, which will affect the surface tension and evaporation rate of the droplets. When the negative pressure suddenly increases, droplets may be adsorbed onto the battery surface more quickly, resulting in an increase in local film thickness. Conversely, when the negative pressure suddenly decreases, droplet transport and deposition may be hindered, leading to gaps or insufficient thickness in the film. Therefore, precisely controlling the negative pressure inside the shield and keeping it stable is crucial for obtaining a uniform, dense, and high-quality polymer protective film.

[0024] (4) The spraying method of this invention is simple to prepare, suitable for large-area mass production, and has low cost. Due to the low temperature of the preparation process, thermal damage to the perovskite material can be effectively avoided, thus effectively maintaining the stability of the perovskite battery. At the same time, it can reduce the risk of lead and toxic perovskite substances leaking into the environment. In addition, polymer materials can reduce the mismatch of thermal expansion coefficients between the layers, avoid interface delamination or breakage, thereby improving the yield of the module. Attached Figure Description

[0025] Figure 1 The image shows a comparison of the water contact angles before and after applying the protective layer to the perovskite solar cell in Example 1. Image a shows the angle before applying the protective layer, and image b shows the angle after applying the protective layer. Figure 2 Here is a schematic diagram of the perovskite solar cell with a protective layer prepared according to the present invention: Figure 3 This is a schematic diagram of ultrasonic spraying in Example 1; Figure 4 This is a schematic diagram of electrostatic spraying in Example 3; Figure 5 This is a schematic diagram of pneumatic spraying in Example 4. Figure 6 This is a schematic diagram of thermal spraying in Example 5. Figure 7 This is a schematic diagram of the nitrogen atmosphere in the sealed enclosure of the spraying method of the present invention; Figure 8 This is a schematic diagram of the negative pressure in the sealed cover of the spraying method of the present invention. Detailed Implementation

[0026] 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.

[0027] Example 1 A method for preparing a protective layer for a perovskite solar cell, the perovskite solar cell comprising a conductive substrate, a charge transport layer 1, a perovskite light-absorbing layer, a charge transport layer 2, and a thin film electrode stacked sequentially, wherein a protective layer is prepared on the surface and surrounding edges of the perovskite solar cell by spraying. The preparation of the protective layer includes the following steps: Step 1: Use ultrasonic spraying to spray a 10wt% DOWSIL1-2577 silicon conformal coating material solution onto the surface and four edges of the solar cell; wherein: the spray gun nozzle diameter is 2.0mm, the spraying pressure is controlled at 0.3MPa, the spraying distance is 25cm, and the spraying is repeated 1-5 times according to the required thickness; During the spraying process, the perovskite solar cells and spray gun are covered by a sealed enclosure, and nitrogen gas is introduced into the enclosure. The sealed enclosure consists of the enclosure body, an air inlet device, an air outlet device, and a control system. The enclosure body needs to be made of materials with good sealing performance, such as stainless steel or high-strength plastic, to ensure effective isolation of the internal spraying system from the external environment. The air inlet device is located on one side of the enclosure body and is used to control the flow rate and purity of the gas to ensure that the spraying environment has low water and oxygen (water content <1ppm, oxygen content <1ppm) to maintain a specific atmosphere inside the enclosure. The air outlet device is located on the other side of the enclosure body and is connected to the exhaust equipment to extract excess gas from the enclosure body to maintain a stable atmosphere inside the enclosure. The control system is responsible for monitoring and adjusting various parameters inside the enclosure, such as pressure, temperature, and humidity, to ensure that the entire preparation process is carried out under stable conditions. Step 2: Anneal the device coated with polymer material at a temperature of 110℃ for 15 minutes.

[0028] The perovskite solar cell in this embodiment was prepared using the following method: Cleaning the conductive substrate: Clean the conductive substrate with alkaline solution and deionized water and dry it for later use. Fabrication of the ITO functional layer: Using magnetron sputtering, a cleaned stainless steel foil conductive substrate was placed into a chamber, and the chamber was evacuated to a vacuum level of less than 2.0 × 10⁻⁶. -4 Pa, 20 sccm of Ar / O2 mixed gas (Ar:O2=95:5), power 200 W, working gas pressure 5 mTorr, rotation speed 0.4 rpm, sputtering ITO functional layer on conductive substrate surface; Fabrication of the NiOx hole transport layer: A conductive substrate / ITO was placed in a chamber using magnetron sputtering, and the chamber was evacuated to a vacuum level of less than 2.0 × 10⁻⁶. -4 Pa, 12 sccm of Ar / O2 mixed gas (Ar:O2=95:5) and 8 sccm of O2 were introduced, power 140w, working pressure 2mTorr, rotation speed 0.4 rpm, sputtering hole transport layer (NiOx layer), after the NiOx layer was prepared, the substrate was annealed and crystallized at 300℃ for 1h, and the substrate was allowed to cool naturally; Spraying the perovskite light-absorbing layer: Use a spray nozzle with a diameter of 1.8 mm, a spraying pressure of 0.5 MPa, a spraying distance of 20 cm, and a spraying speed of 6 mm / s to ensure that the substrate is completely covered. Repeat the spraying 1-5 times according to the required thickness. The precursor concentration of the spraying solution is 1 M. Extraction is performed using an air knife with a pressure of 0.8 MPa. After completion, the sample is annealed at 110 °C for 30 min. Preparation of electron transport layer: After the above process, a conductive substrate / ITO / NiOx / PVK sample is obtained. An electron transport layer (PCBM) is sprayed on the surface of the sample. The nozzle diameter is 1.2 mm, the spraying pressure is controlled at 0.3 MPa, the spraying distance is 20 cm, and the spraying speed is 6 mm / s. While ensuring that the substrate is completely covered, the spraying is repeated 1-5 times according to the required thickness. After the electron transport layer is prepared, 2.5 wt% zinc oxide nanoparticle isopropanol dispersion is scraped onto the surface of the electron transport layer as a protective barrier layer using the same process. After scraping, annealing is performed at 100℃ for 10 min. 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 background vacuum is 20 mTorr, the power is 180 W, the rotation speed is 0.2 rpm, the working gas pressure is 5 mTorr, and 20 sccm of Ar / O2 mixed gas (Ar:O2=95:5) is introduced.

[0029] 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.

[0030] Table 1

[0031] Example 2 The difference from Example 1 is that during the spraying process, the perovskite solar cell and spray gun are covered with a sealed cover to maintain negative pressure on the cover and control the water content and oxygen content of the spraying environment to be <0.1ppm and <0.1ppm, respectively. The other operating conditions are the same as in Example 1.

[0032] Example 3 The method for preparing the protective layer in Example 1 was changed from ultrasonic spraying to electrostatic spraying, while the other operating conditions remained the same as in Example 1.

[0033] Example 4 The method for preparing the protective layer in Example 1 was changed from ultrasonic spraying to pneumatic spraying, while the other operating conditions remained the same as in Example 1.

[0034] Example 5 The method for preparing the protective layer in Example 1 was changed from ultrasonic spraying to thermal spraying, while the other operating conditions remained the same as in Example 1.

[0035] 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 method for preparing a protective layer for a perovskite solar cell, the perovskite solar cell comprising a conductive substrate, a charge transport layer 1, a perovskite light-absorbing layer, a charge transport layer 2, and a thin-film electrode stacked sequentially, characterized in that: A protective layer was prepared on the surface and surrounding edges of the perovskite solar cell using a spraying method.

2. The method for preparing the protective layer of a perovskite solar cell according to claim 1, characterized in that, The spraying method includes one of ultrasonic spraying, electrostatic spraying, pneumatic spraying, and thermal spraying.

3. The method for preparing the protective layer of a perovskite solar cell according to claim 1, characterized in that, The preparation of the protective layer includes the following steps: Step 1: Cover the perovskite solar cell and spray gun with a sealed cover, introduce nitrogen into the sealed cover or maintain negative pressure in the cover, and spray the polymer material solution onto the surface and edges of the solar cell. Step 2: Anneal the device coated with polymer material.

4. The method for preparing the protective layer of a perovskite solar cell according to claim 3, characterized in that, In step 1, the polymer material includes one of polyethylene, polypropylene, polymethyl methacrylate, polyvinyl butyral, and silicon-based polymers. The concentration of the polymer solution is 5-20 wt%; The spray gun nozzle has a diameter of 0.5-2.0 mm, the spraying pressure is controlled at 0.1-0.5 MPa, and the spraying distance is 10-30 cm.

5. The method for preparing the protective layer of a perovskite solar cell according to claim 3, characterized in that, In step 2, the annealing temperature is 100-130℃ and the annealing time is 10-30 minutes.

6. The method for preparing the protective layer of a perovskite solar cell according to claim 1, characterized in that, The conductive substrate is a polymer covered by conductive glass, stainless steel foil, or a metal film.

7. The method for preparing the protective layer of a perovskite solar cell 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.

8. The method for preparing the protective layer of a perovskite solar cell according to claim 7, characterized in that... The hole transport layer is NiO. X ; The electron transport layer is one or more of fullerene and its derivatives, copper bath, zinc oxide, and tin oxide.

9. The method for preparing the protective layer of a 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, where 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, in which part of Cs, MA or FA is replaced by an alkali metal or one kind of alkali metal with a weight content less than 10% of each of them.

10. The method for preparing the protective layer of a perovskite solar cell according to claim 1, characterized in that, The thin-film electrode is one of aluminum, nickel, chromium, silver, copper, gold, ITO, FTO, and AZO.

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