A method for stabilizing perovskite surface interface

Abstract

The application provides a method for stabilizing a perovskite surface interface, and belongs to the technical field of perovskite. The method uses the property that a high-molecular complexing agent such as alginic acid combines with metal ions to generate stable gel, adds a certain amount of salt of metal ions with valence of two or more in a perovskite precursor solution for preparing a perovskite battery, and then uses a high-molecular complexing agent solution such as an alginic acid solution to post-treat the surface interface of a thin film in the process of forming a perovskite solution into a film, so that defects caused by the surface interface are effectively repaired, water molecules in the air are effectively prevented from causing decomposition of the thin film by eroding the surface interface of the perovskite, and the efficiency and stability of the battery are improved.

Description

Technical Field

[0001] This invention belongs to the field of perovskite technology, specifically relating to a method for stabilizing the perovskite surface and interface. Background Technology

[0002] With the global goal of achieving carbon neutrality, photovoltaic (PV) power generation, as a renewable energy source, has become one of the important directions for new energy development in various countries. Currently, silicon-based solar cells are the mainstream in the market, accounting for more than 90%. However, since the second half of 2020, the supply of silicon material has become a major bottleneck for the entire photovoltaic industry. Furthermore, the significant increase in silicon material prices has raised the cost of the entire photovoltaic power generation industry chain, and high-priced modules have a significant inhibitory effect on some end-user demand. Therefore, perovskite solar cells, with their wide availability of raw materials, simple manufacturing process, and conversion efficiency comparable to or even surpassing silicon-based cells, are gradually showing enormous commercial potential.

[0003] Furthermore, unlike traditional crystalline silicon solar cells which only absorb visible and near-infrared light from sunlight, and where photons in the visible region exhibit thermal relaxation leading to energy loss as heat, perovskite solar cells possess superior low-light response. Moreover, by employing perovskite and silicon-based tandem solar cell technology—that is, directly fabricating perovskite thin-film devices capable of efficiently converting visible light on the surface of crystalline silicon cells—the combination of the two theoretically can significantly overcome the theoretical limits of single-junction solar cells. This demonstrates the feasibility and immense potential of using perovskite solar cell technology to substantially break through the theoretical limits of silicon-based single-junction solar cells.

[0004] However, the instability of perovskites under conditions such as heat, oxygen, ultraviolet light, and water is one of the important challenges facing their further large-scale commercial production. A series of interface optimization schemes, especially perovskite thin film surface passivation, have been proven to be one of the effective strategies for obtaining high-quality and stable perovskite devices.

[0005] Patent (CN110492000A) relates to a perovskite photodetector based on a sodium alginate cross-linked photoactive layer and its fabrication method. The photodetector, from bottom to top, comprises: a transparent substrate, a conductive anode, a hole transport layer, a perovskite photoactive layer, an electron transport layer, a hole blocking layer, and a metal cathode. The perovskite photoactive layer is a composite film composed of organic-inorganic hybrid perovskite MAPbI3 and the biomaterial sodium alginate, with the amount of sodium alginate added to the film being 0.05%-1%. Utilizing the cross-linking effect and good conductivity of sodium alginate, the film quality and carrier transport capacity of the original perovskite photoactive layer are improved, the carrier recombination probability is reduced, effectively increasing the photocurrent of the detector and reducing the dark current of the device, thereby improving the device's detection performance. Simultaneously, the photoactive layer doped with sodium alginate has good resistance to water and oxygen, effectively reducing the corrosion of the device by water and oxygen, thereby improving the stability and lifespan of the perovskite photodetector.

[0006] Patent (CN113809240A) relates to a method for passivating a perovskite thin film layer and its application in solar cells. This invention uses N,N-dimethylethylenediamine as a complexing agent, utilizing the chelating effect between N,N-dimethylethylenediamine and perovskite to passivate the surface of the perovskite thin film layer. The perovskite thin film layer obtained by the above passivation method exhibits excellent moisture resistance and a low surface defect state density. Using this perovskite thin film layer as a light-absorbing layer to fabricate perovskite solar cells can simultaneously improve the photoelectric conversion efficiency and operational stability of the cell device.

[0007] Patent (CN114497390A) relates to a perovskite solar cell and its fabrication method. The perovskite solar cell of this invention includes a conductive glass layer, an electron transport layer, an interface modification layer, a perovskite light-absorbing layer, a hole transport layer, and a metal electrode layer. The perovskite light-absorbing layer film is doped with a certain concentration of arginine and then annealed. The interface modification layer is a sodium alginate film layer. After arginine doping, the perovskite light-absorbing layer film exhibits stronger crystallinity and a smoother surface. Combined with the interface modification of sodium alginate, the dangling bonds on the perovskite layer surface between the electron transport layer and the perovskite light-absorbing layer can be passivated, thereby reducing the binding of carriers by deep-level defects, effectively reducing the contact between the electron transport layer and the hole transport layer, reducing leakage current, improving photoelectric conversion efficiency, and helping to prevent oxygen infiltration and reduce perovskite material oxidation.

[0008] However, due to the wide variety of defects at the surface and interface, relying on a single passivation or weak coordination bonds to passivate the surface and interface is often insufficient to achieve long-term stability of perovskite surface and interface defects.

[0009] This invention utilizes the property of polymeric complexing agents such as alginate to combine with metal ions to form a stable gel. A certain amount of divalent or higher metal ion salts are added to the perovskite precursor solution used to prepare the perovskite battery. Subsequently, during the perovskite solution film formation process, the surface and interface of the film are post-treated using polymeric complexing agent solutions such as alginate solution. This effectively repairs defects caused by the surface and interface, effectively preventing the film decomposition caused by water molecules in the air eroding the perovskite surface and interface, thereby improving the efficiency and stability of the battery. Summary of the Invention

[0010] This invention addresses the problems existing in the prior art by providing a method for stabilizing the perovskite surface interface. This invention utilizes the property of polymeric complexing agents such as alginate to combine with metal ions to form a stable gel. A certain amount of divalent or higher metal ion salts is added to the perovskite precursor solution used in preparing perovskite batteries. Subsequently, during the perovskite solution film formation process, the surface interface is post-treated using alginate solution or other polymeric complexing agent solutions. This effectively repairs defects caused by the surface interface, effectively preventing film decomposition caused by water molecules in the air eroding the perovskite surface interface, and improving the battery's efficiency and stability.

[0011] To achieve the above objectives, the present invention provides a method for stabilizing perovskite interfaces, comprising the following steps:

[0012] 1) Add a certain amount of metal ion salt to the perovskite precursor solution to form a CsPbI2Br precursor solution containing metal ions.

[0013] 2) Prepare a polymeric complexing agent solution using the polymeric complexing agent;

[0014] 3) The CsPbI2Br precursor solution containing metal ions prepared in step 1) is spin-coated onto the electron layer thin film substrate to form a perovskite thin film. Then, the polymer complexing agent solution prepared in step 2) is spin-coated onto the surface of the perovskite thin film. The perovskite thin film is then encapsulated at the interface using the polymer complexing agent. After the encapsulation, the perovskite thin film is assembled into a complete battery device using the standard perovskite solar cell process.

[0015] In a preferred embodiment, after spin-coating the polymer complexing agent solution in step 3), the method further includes spin-coating a simple isopropanol solution to rinse off excess alginate solution.

[0016] In a preferred embodiment, the metal ion salt is selected from metal salts of Cu, Zn, Mn, Cr, and Ca, and more preferably calcium chloride and zinc chloride.

[0017] In a preferred embodiment, the metal ion salt is added to the perovskite precursor solution in powder or solution form. The solution preparation process of the metal ion salt is as follows: the metal ion salt powder is dissolved in a solvent and stirred at room temperature for 8-12 hours to form a solution, wherein the solvent is selected from ethanol, isopropanol, or n-butanol.

[0018] In a preferred embodiment, the metal ion-containing CsPbI2Br precursor solution is selected from Ca-CsPbI2Br and Zn-CsPbI2Br; the concentration of the metal ion salt is 0.01-100 mg / ml.

[0019] In a preferred embodiment, the titanium ore precursor solution is a 0.8-1.3 mol / L CsPbI2Br perovskite solution.

[0020] In a preferred embodiment, the polymeric complexing agent is selected from one or more of alginate, sodium alginate, potassium alginate, guar gum, starch, or cellulose.

[0021] In a preferred embodiment, the process of assembling the treated perovskite solar cell into a complete battery device using standard perovskite solar cell procedures is as follows: spin-coating a hole transport layer onto the surface of the treated perovskite thin film and evaporating the corresponding Ag electrode.

[0022] After assembling perovskite solar cells using standard processes, their photoelectric conversion efficiency was tested under standard solar irradiance conditions.

[0023] The beneficial effects of this invention are as follows:

[0024] (1) The preparation method of this invention is simple and the source of the drug is safe. The preferred polymer complexing agent, such as alginate polysaccharide molecules, is non-toxic and environmentally friendly compared with other metal-stabilized complexing agents and can be widely used.

[0025] (2) The method of the present invention is universal. Alginate polysaccharide molecule solution is just one example of a stable complexing agent that can form with the metals mentioned above. There are many types of metal ions and complexing agents that can be used and they are easy to obtain. The optimal combination of passivating perovskite film surface and interface can be widely selected.

[0026] (3) This invention utilizes alginate polysaccharide molecules to form stable hydrophobic calcium alginate gel material by complexing with metal ions such as Ca and Zn present at the perovskite interface, thereby effectively preventing the film decomposition caused by water molecules in the air eroding the perovskite interface, and effectively improving the efficiency and stability of perovskite batteries. Attached Figure Description

[0027] Figure 1 The perovskite thin film prepared in Example 1.

[0028] Figure 2 The perovskite thin film prepared in Comparative Example 1 is shown. Detailed Implementation

[0029] It is worth noting that the raw materials used in this invention are all commercially available products, and their sources are not specifically limited.

[0030] Example 1

[0031] 1) Preparation of TiO2 electron transport layer:

[0032] FTO conductive glass was immersed in a TiCl4 solution (concentration 25 mol / ml) in a petri dish and kept at 70°C for 60 minutes. Then, the residual TiCl4 solution on the FTO surface was rinsed with deionized water and anhydrous ethanol, dried with a hair dryer, and then calcined in a muffle furnace at 500°C for 60 minutes. After natural cooling, a dense TiO2 film was formed.

[0033] 2) Preparation of perovskite precursor solution:

[0034] Weigh 272 mg of cesium iodide, 187 mg of lead bromide, 235.5 mg of lead iodide and 2 mg / ml of CaCl2 powder and dissolve them in 1 mL of dimethyl sulfoxide solvent. Then stir at room temperature for 12 hours to form a perovskite Ca-CsPbI2Br precursor solution.

[0035] 3) Preparation of alginic acid solution:

[0036] Weigh 2 mg of alginate powder and dissolve it in 10 mL of isopropanol solvent. Then stir at room temperature for 12 hours to form an alginate solution.

[0037] 4) Fabrication of perovskite thin films and devices:

[0038] Subsequently, 50 μL of the perovskite Ca-CsPbI2Br precursor solution was spin-coated onto the aforementioned TiO2 thin film substrate. The film was heated at 160 °C for 10 minutes, and after cooling for 10 minutes, 50 μL of alginate isopropanol solution was spin-coated onto the surface, followed by heating at 160 °C for 10 minutes. After cooling, 20 μL of the corresponding pure isopropanol solution was spin-coated to rinse off excess alginate solution, and the film was heated at 100 °C for 3 minutes. After cooling, a poly-3-hexylthiophene (P3HT) hole layer (15 mg / ml chlorobenzene solution) was spin-coated, and a silver electrode (80 nm thick) was deposited, assembling the corresponding perovskite solar cell. Using a solar simulator, the solar cell was tested at 100 mW / cm². -2 The photoelectric conversion efficiency was tested under standard light illumination. The effective area of ​​the cell was 0.0625 cm². 2 . Figure 1 It is the perovskite thin film prepared in Example 1.

[0039] Example 2

[0040] Steps 1)-2): Same as in Example 1.

[0041] 3) Preparation of sodium alginate solution:

[0042] Weigh 2 mg of sodium alginate powder and dissolve it in 10 mL of isopropanol solvent. Then stir at room temperature for 12 hours to form a sodium alginate isopropanol solution.

[0043] 4) Fabrication of perovskite thin films and devices: Subsequently, 50 μL of perovskite Ca-CsPbI2Br precursor solution was spin-coated onto the above-mentioned TiO2 thin film substrate, heated at 160°C for 10 minutes, and after the film cooled for 10 minutes, 50 μL of sodium alginate isopropanol solution was spin-coated onto the surface, followed by heating at 160°C for 10 minutes. After the film cooled, a poly-3-hexylthiophene (P3HT) hole layer (15 mg / ml chlorobenzene solution) was spin-coated, and a silver electrode (80 nm thick) was deposited by vapor deposition to assemble the corresponding perovskite solar cell. Using a solar simulator, at 100 mW / cm², the solar cells were tested. -2 The photoelectric conversion efficiency was tested under standard light illumination. The effective area of ​​the cell was 0.0625 cm². 2 .

[0044] Example 3

[0045] 1) The preparation of the TiO2 electron transport layer is the same as in Example 1:

[0046] 2) Preparation of Zn-CsPbI2Br perovskite precursor solution: Weigh 272 mg of cesium iodide, 187 mg of lead bromide, 235.5 mg of lead iodide and 2 mg / ml of ZnCl2 powder and dissolve them in 1 mL of dimethyl sulfoxide solvent. Then stir at room temperature for 12 hours to form perovskite Zn-CsPbI2Br precursor solution.

[0047] 3) The preparation of the alginate solution is the same as in Example 1.

[0048] 4) Preparation of perovskite thin films and devices: Same as in Example 1.

[0049] Example 4

[0050] 1) The preparation of the TiO2 electron transport layer is the same as in Example 1:

[0051] 2) The Zn-CsPbI2Br perovskite precursor solution was prepared in the same manner as in Example 3.

[0052] 3) The preparation of sodium alginate solution is the same as in Example 2.

[0053] 4) Preparation of perovskite thin films and devices: Except for spin-coating the perovskite thin film surface with 50 μl of alginate isopropanol solution, followed by heating at 160°C for 10 minutes, and after the film cools down, spin-coating with 20 μl of the corresponding pure isopropanol solution to rinse off excess alginate solution, the rest of the process is the same as in Example 1.

[0054] Example 5

[0055] 1) Preparation of TiO2 electron transport layer: Same as in Example 1.

[0056] 2) Preparation of perovskite precursor solution: Same as in Example 1.

[0057] 3) Preparation of alginate solution: Same as in Example 1.

[0058] 4) Preparation of perovskite thin films and devices: Same as in Example 4.

[0059] Comparative Example 1

[0060] 1) Preparation of TiO2 electron transport layer: Same as in Example 1.

[0061] 2) Preparation of perovskite precursor solution: Weigh 272 mg cesium iodide, 187 mg lead bromide, and 235.5 mg lead iodide powder and dissolve them in 1 mL of dimethyl sulfoxide solvent. Then stir at room temperature for 12 hours to form perovskite CsPbI2Br precursor solution.

[0062] 3) Fabrication of perovskite thin films and devices: Subsequently, 50 μL of perovskite CsPbI2Br precursor solution was spin-coated onto the above-mentioned TiO2 thin film substrate, and heated at 160℃ for 10 minutes to form the corresponding perovskite absorber layer film. After the film cooled, a poly-3-hexylthiophene (P3HT) hole layer (15 mg / ml chlorobenzene solution) was spin-coated, and a silver electrode (80 nm thick) was deposited by evaporation to assemble the corresponding perovskite solar cell. Using a solar simulator, at 100 mW / cm², the solar cells were tested. -2 The photoelectric conversion efficiency was tested under standard light illumination. The effective area of ​​the cell was 0.0625 cm². 2 . Figure 2 This is the perovskite thin film prepared in Comparative Example 1.

[0063] Comparative Example 2

[0064] 1) Preparation of TiO2 electron transport layer: Same as in Example 1.

[0065] 2) Preparation of perovskite precursor solution: Same as comparative example 1.

[0066] 3) Preparation of alginate solution: Same as in Example 1.

[0067] 4) Preparation of perovskite thin films and devices: Same as in Example 1.

[0068] Test Example: Photoelectric Conversion Efficiency Test

[0069] Using a solar simulator, at 100mWcm -2 The photoelectric conversion efficiency was tested under standard light illumination. The results are shown in Table 1.

[0070] Table 1

[0071]

[0072] Compared with Comparative Example 1, Examples 1-2 show that using alginate and CaCl2 to form an interface stitching modification can further improve the photoelectric conversion efficiency of the battery device. Furthermore, comparing Example 1 with Comparative Examples 1 and 2 shows that adding CaCl2 to the perovskite precursor solution can enhance the interfacial interaction between alginate and the perovskite film, thereby improving the photoelectric conversion efficiency of the battery device. A comparison between Examples 1 and 5 shows that after spin-coating the alginate solution, spin-coating with a simple isopropanol solution to rinse away excess alginate solution can improve the photoelectric conversion efficiency of the battery device.

[0073] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A method for stabilizing perovskite interfaces, characterized in that, Includes the following steps: 1) Add a certain amount of metal ion salt to the perovskite precursor solution to form a CsPbI2Br precursor solution containing metal ions. 2) Prepare a polymeric complexing agent solution using the polymeric complexing agent; 3) Take the CsPbI2Br precursor solution containing metal ions prepared in step 1) and spin-coat it onto the electron layer thin film substrate to form a perovskite thin film. Then take the polymer complexing agent solution prepared in step 2) and spin-coat it on the surface of the perovskite thin film. Use the polymer complexing agent to perform interface encapsulation treatment on the perovskite thin film. After treatment, assemble it into a complete battery device using the standard perovskite solar cell process. The metal ion salts mentioned are selected from the metal salts of Zn and Ca; The polymeric complexing agent is selected from one or more of alginate, sodium alginate, or potassium alginate; The process of assembling a complete battery device using standard perovskite solar cell procedures after the treatment is as follows: spin-coating a hole transport layer onto the surface of the treated perovskite thin film and evaporating the corresponding Ag electrode.

2. The method as described in claim 1, characterized in that, Step 3) includes a spin-coating process after applying the polymer complexing agent solution, followed by a spin-coating process with a simple isopropanol solution to rinse off any excess polymer complexing agent solution.

3. The method as described in claim 1, characterized in that, The metal ion salts mentioned are selected from calcium chloride and zinc chloride.

4. The method as described in claim 1, characterized in that, The metal ion salt is added to the perovskite precursor solution in powder or solution form; The CsPbI2Br precursor solution containing metal ions is selected from Ca-CsPbI2Br and Zn-CsPbI2Br; the concentration of the metal ion salt is 0.01-100 mg / ml.

5. The method as described in claim 1, characterized in that, The perovskite precursor solution is a 0.8-1.3 mol / L CsPbI2Br perovskite solution; the polymer complexing agent solution is a solution obtained by dissolving the polymer complexing agent in a solvent, with a concentration range of 0.05-1 mg / ml; the solvent is selected from isopropanol, ethanol or n-butanol.

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