A perovskite solar cell based on metal fluoride modification and a preparation method thereof

Abstract

The application relates to the technical field of solar cells, in particular to a perovskite solar cell based on metal fluoride modification and a preparation method thereof. The cell comprises, from bottom to top, a conductive substrate, a first charge transport layer, a perovskite layer, a second charge transport layer and an electrode, and a metal fluoride prepared by gas phase deposition is used as a modification layer and is deposited on the upper surface of the perovskite layer and / or a buried bottom interface; the metal fluoride is any one of strontium fluoride and cerium trifluoride. The method has the characteristics that carriers can tunnel through an insulating thin layer, can passivate interface defects, and can reduce the recombination rate of photo-generated carriers. Therefore, the insulating thin layer is used to modify the perovskite interface, the product of the open circuit voltage and the fill factor of the perovskite solar cell is improved, and the photoelectric conversion capability is enhanced. Meanwhile, the ion migration of the perovskite and the diffusion of the metal electrode can be inhibited, and the long-term stability of the device can be obviously improved.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, specifically to a perovskite solar cell based on metal fluoride modification and its preparation method. Background Technology

[0002] With the development of modern industry and the increase in population, energy issues have become an urgent problem to be solved. Currently, our energy sources are mainly fossil fuels, which have limited reserves and cause environmental pollution. Therefore, finding, developing, and utilizing clean energy is imperative. Solar energy, as one of the new energy sources, can be continuously utilized, and solar cells, as a technology that directly converts solar energy into electricity, have received widespread attention in recent years.

[0003] Currently, most solar cells on the market are devices composed of monocrystalline silicon. However, the fabrication of high-purity silicon absorber layers requires high temperatures, making the fabrication technology complex and costly. Perovskite solar cells, on the other hand, are relatively low-cost and are predicted to achieve higher efficiencies, enabling large-scale industrial production. Perovskite solar cells can be classified into two types based on their device structure: formal and inverted. The core technologies of perovskite solar cells include the fabrication of the perovskite light-absorbing layer, the optimization of the charge transport layer, and the passivation of interface defects. In particular, interface passivation technology is crucial for reducing charge recombination losses and improving device performance.

[0004] Currently, researchers are dedicated to studying methods to suppress recombination at the perovskite / charge transport layer interface and have made some progress. However, device performance remains low, still in the initial development stage, and efficiency is far from meeting commercial requirements, leaving significant room for improvement. Furthermore, most passivation techniques developed at this stage employ solution methods, which are incompatible with the vacuum method widely used in industrial processes for preparing charge transport layers. These shortcomings severely restrict the industrialization of perovskite solar cells, necessitating the development of novel passivation techniques for the perovskite / charge transport layer interface that are compatible with industrial production processes. Summary of the Invention

[0005] To overcome the shortcomings in the energy conversion efficiency of existing methods and devices, this invention aims to provide a perovskite solar cell based on metal fluoride modification and its fabrication method. This invention uses a vapor-deposited dipole fluoride thin layer as the modification layer, utilizing the ability of charge carriers to tunnel through the insulating thin layer. This not only passivates interface defects but also reduces the recombination rate of photogenerated carriers, thereby improving the performance of perovskite solar cells with simple operation and lower cost.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] The present invention provides a perovskite solar cell based on metal fluoride modification. The cell consists of a conductive substrate, a first charge transport layer, a perovskite layer, a second charge transport layer and an electrode from bottom to top. A metal fluoride is deposited as a modification layer on the upper surface and / or buried interface of the perovskite layer by vapor deposition. The metal fluoride is either strontium fluoride or cerium trifluoride.

[0008] In the above technical solution, the thickness of the modification layer is further 0.1-2 nm.

[0009] In the above technical solution, the perovskite layer further has the following structure: Cs 0.1 FA 0.9 PbI 2.76 Br 0.24 In this system, Cs represents cesium atoms, FA represents formamidinium cations, Pb represents lead atoms, I represents iodine atoms, and Br represents bromine atoms.

[0010] Another aspect of the present invention provides a method for preparing the above-mentioned perovskite solar cell, the method comprising the following steps:

[0011] Step 11: Pre-treat the conductive substrate and prepare the first charge transport layer on the conductive substrate;

[0012] Step 12: Prepare a buried interface modification layer on the first charge transport layer using vapor deposition;

[0013] Step 13: Prepare a perovskite layer on the buried interface modification layer;

[0014] Step 14: Prepare a second charge transport layer on the perovskite layer;

[0015] Step 15: Fabricate electrodes on the second charge transport layer.

[0016] Or the method may include the following steps:

[0017] Step 21: Pre-treat the conductive substrate and prepare the first charge transport layer on the conductive substrate;

[0018] Step 22: Prepare a perovskite layer on the first charge transport layer;

[0019] Step 23: Prepare an upper surface modification layer on the perovskite layer using a vapor deposition method;

[0020] Step 24: Prepare a second charge transport layer on the upper surface modification layer;

[0021] Step 25: Fabricate electrodes on the second charge transport layer.

[0022] Or the method may include the following steps:

[0023] Step 31: Pre-treat the conductive substrate and prepare the first charge transport layer on the conductive substrate;

[0024] Step 32: Prepare a buried interface modification layer on the first charge transport layer using a vapor deposition method;

[0025] Step 33: Prepare a perovskite layer on the buried interface modification layer;

[0026] Step 34: Prepare an upper surface modification layer on the perovskite layer using a vapor deposition method;

[0027] Step 35: Prepare a second charge transport layer on the upper surface modification layer;

[0028] Step 36: Fabricate electrodes on the second charge transport layer.

[0029] In the above technical solution, the deposition rate of the modified layer is further 0.01-1 nm per 100 s.

[0030] In the above technical solution, the vapor deposition method further includes physical vapor deposition.

[0031] The beneficial effects of this invention are as follows:

[0032] (1) This invention uses fluoride as a modifying material, which is deposited on the upper surface and / or buried interface (lower surface) of perovskite by vapor deposition. Utilizing the ability of charge carriers to tunnel through the insulating thin layer, this not only passivates interface defects but also reduces the recombination rate of photogenerated carriers, thereby increasing the product of the open-circuit voltage and fill factor of the perovskite solar cell and enhancing its photoelectric conversion capability. Furthermore, this invention can suppress ion migration in the perovskite and diffusion in the metal electrode, significantly improving the long-term stability of the device.

[0033] (2) Compared with traditional organic ammonium salt passivation materials, fluorides are cheaper, have more stable chemical properties, and are easier to prepare into films using vapor deposition processes. While improving the efficiency and stability of solar cells, they are also more environmentally friendly and in line with the development concept of green chemistry.

[0034] (3) The present invention uses vapor deposition technology, which not only makes it easy to ensure the uniformity of the modified layer and facilitates large-area preparation, but also makes it compatible with the process of vacuum preparation of charge transport layer widely used in industry, realizing continuous vacuum preparation, which is conducive to the industrialization of perovskite battery. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of the perovskite solar cell prepared in Example 1;

[0036] Figure 2A schematic diagram of the process for preparing the modified layer using thermal evaporation technology;

[0037] Figure 3 A schematic diagram of the process for preparing the modification layer using magnetron sputtering technology;

[0038] Figure 4 The JV diagrams are for the perovskite solar cells prepared in Comparative Example 1, Comparative Example 2, and Example 1. Detailed Implementation

[0039] To further understand the method of the present invention, preferred embodiments of the present invention are now provided, and detailed descriptions are given below with accompanying drawings.

[0040] Unless otherwise specified, the materials used in the embodiments of the present invention can be obtained commercially or prepared according to conventional methods known to those skilled in the art.

[0041] Example 1

[0042] (1) The conductive glass was cleaned sequentially with acetone, isopropanol, and deionized water. It was then treated with ultraviolet ozone for 20 minutes. Finally, the conductive glass was placed in a thermal evaporation device and subjected to high vacuum (<1.5*10⁻⁶). -3 Pa), evaporate a 50 nm nickel oxide film, and then anneal it on a hot plate at 200 °C for 40 min;

[0043] (2) Place the conductive glass coated with nickel oxide in a vacuum evaporation apparatus and evaporate it under a high vacuum environment (<1*10). -3 Using strontium fluoride powder as the evaporation source, 0.5 nm strontium fluoride was thermally evaporated at a rate of 0.05 nm per 100 s to prepare a modification layer for the buried interface.

[0044] (3) The prepared sample was transferred to a nitrogen atmosphere and spin-coated with 1.35M Cs at 1000 rpm / min for 10 s and 4000 rpm / min for 40 s on the surface. 0.1 FA 0.9 PbI 2.76 Br 0.24 The perovskite precursor solution was annealed at 150 μL of antisolvent chlorobenzene in the last 20 seconds on a hot plate at 150 °C for 30 min to obtain the perovskite layer.

[0045] (4) Transfer the perovskite layer to a vacuum evaporator and deposit it under a high vacuum environment (<1*10). -3 Using cerium trifluoride powder as the evaporation source, cerium trifluoride of 0.5 nm was prepared by thermal evaporation at a rate of 0.1 nm per 100 s, and used as the upper surface modification layer.

[0046] (5) In a vacuum evaporation apparatus, C 30 nm was continuously deposited.60 A perovskite solar cell was prepared by depositing 5 nm of BCP (2,9-dimethyl-4,7-biphenyl-1,10-phenanthroline) onto the surface of the BCP, followed by depositing silver onto the surface of the BCP to a thickness of 150 nm.

[0047] Example 2

[0048] The preparation method is the same as in Example 1, except that the modification layer is deposited only on the upper surface of the perovskite layer.

[0049] Example 3

[0050] The preparation method is the same as in Example 1, except that the modified layer is deposited only at the buried interface of the perovskite layer.

[0051] Example 4

[0052] The preparation method is the same as in Example 1, except that the fluoride in step (2) is cerium trifluoride.

[0053] Example 5

[0054] The preparation method is the same as in Example 1, except that the fluoride in step (4) is strontium fluoride.

[0055] Example 6

[0056] The preparation method is the same as in Example 1, except that the thickness of the fluoride in steps (2) and (4) is 1 nm.

[0057] Example 7

[0058] The preparation method is the same as in Example 1, except that steps (2) and (4) use electron beam evaporation technology to deposit the modified layer. The specific deposition parameters are: in a high vacuum environment (<1.5*10 -3 By adjusting the incident electron beam power, the fluoride deposition rate was controlled to be 0.1 nm per 100 s.

[0059] Example 8

[0060] The preparation method is the same as in Example 1, except that steps (2) and (4) use magnetron sputtering technology to deposit the modified layer. The specific deposition parameters are: in a high vacuum environment (<5*10 -4 By adjusting the input power, the fluoride deposition rate is controlled to be 0.2 nm per 100 s.

[0061] Comparative Example 1

[0062] The modification method described in Example 1 differs in that steps (2) and (4) are omitted.

[0063] Comparative Example 2

[0064] The modification method described in Example 1 differs in that the fluoride used in steps (2) and (4) is magnesium fluoride.

[0065] Test Example 1

[0066] AM1.5G sunlight was simulated using a solar simulator, and the JV characteristic curves of the perovskite solar cell devices prepared in Example 1 and Comparative Examples 1-2 under optical conditions were tested using a source measurement unit. The scan direction was from 1.3V to -0.1V, with a step size of -0.02V. The test results are as follows: Figure 1 As shown.

[0067] The performance test results of the perovskite solar cells prepared in Examples 1-8 and Comparative Examples 1-2 are shown in Table 1.

[0068] Table 1

[0069]

[0070]

[0071] The above content provides a detailed description of the present invention. Any similar implementations made without departing from the method of the present invention should fall within the protection scope of the present invention.

Claims

1. A perovskite solar cell based on metal fluoride modification, wherein the cell comprises, from bottom to top, a conductive substrate, a first charge transport layer, a perovskite layer, a second charge transport layer, and an electrode, characterized in that, A metal fluoride is deposited as a modification layer on the upper surface and / or buried interface of the perovskite layer using vapor deposition; the metal fluoride is either strontium fluoride or cerium trifluoride.

2. The perovskite solar cell according to claim 1, characterized in that, The thickness of the modified layer is 0.1-2 nm.

3. The perovskite solar cell according to claim 1, characterized in that, The perovskite layer has the following structure: Cs 0.1 FA 0.9 PbI 2.76 Br 0.24 In this system, Cs represents cesium atoms, FA represents formamidinium cations, Pb represents lead atoms, I represents iodine atoms, and Br represents bromine atoms.

4. A method for preparing a perovskite solar cell according to any one of claims 1-3, characterized in that, The method includes the following steps: Step 11: Pre-treat the conductive substrate and prepare the first charge transport layer on the conductive substrate; Step 12: Prepare a buried interface modification layer on the first charge transport layer using vapor deposition; Step 13: Prepare a perovskite layer on the buried interface modification layer; Step 14: Prepare a second charge transport layer on the perovskite layer; Step 15: Fabricate electrodes on the second charge transport layer.

5. A method for preparing a perovskite solar cell according to any one of claims 1-3, characterized in that, The method includes the following steps: Step 21: Pre-treat the conductive substrate and prepare the first charge transport layer on the conductive substrate; Step 22: Prepare a perovskite layer on the first charge transport layer; Step 23: Prepare an upper surface modification layer on the perovskite layer using a vapor deposition method; Step 24: Prepare a second charge transport layer on the upper surface modification layer; Step 25: Fabricate electrodes on the second charge transport layer.

6. A method for preparing a perovskite solar cell according to any one of claims 1-3, characterized in that, The method includes the following steps: Step 31: Pre-treat the conductive substrate and prepare the first charge transport layer on the conductive substrate; Step 32: Prepare a buried interface modification layer on the first charge transport layer using a vapor deposition method; Step 33: Prepare a perovskite layer on the buried interface modification layer; Step 34: Prepare an upper surface modification layer on the perovskite layer using a vapor deposition method; Step 35: Prepare a second charge transport layer on the upper surface modification layer; Step 36: Fabricate electrodes on the second charge transport layer.

7. The preparation method according to claim 4, 5 or 6, characterized in that, The deposition rate of the modified layer is 0.01-1 nm per 100 s.

8. The preparation method according to claim 4, 5 or 6, characterized in that, The vapor deposition method includes physical vapor deposition.

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