Preparation method of perovskite-polymer thin film and perovskite solar cell

Abstract

The present application relates to the technical field of solar cells, and particularly relates to a preparation method of a perovskite-polymer thin film and a perovskite solar cell, which comprises the following steps: preparing an ABX3 type perovskite precursor solution; preparing a mixed solution of a low-boiling unsaturated monomer and an initiator and adding the mixed solution into the precursor solution, and stirring until the reaction is complete; coating the solution after the reaction is complete on a surface of a substrate, and obtaining the perovskite-polymer thin film after annealing. In the present application, the unsaturated monomer is used as an additive, and before polymerization, the unsaturated monomer has the characteristics of a small molecule, is easy to dissolve, and at the same time, the small molecule is also more easily diffused in the solution, so that the interaction with the perovskite component is less affected by the steric hindrance of the site molecule. However, in the process of perovskite crystallization, the unsaturated monomer is changed into a polymer through in-situ polymerization, and the polymer has the stable characteristics, and at the same time, the hydrophobicity also increases the stability of the perovskite to the water molecules in the air.

Description

Technical Field

[0001] This invention relates to the technical field of solar cells, specifically to a method for preparing a perovskite-polymer thin film and a perovskite solar cell. Background Technology

[0002] With the development of human life and production, the demand for energy is increasing, and currently, the main energy source is still traditional fossil fuels. However, the large-scale consumption of traditional fossil fuels inevitably causes significant environmental pollution, making the development of a new clean energy source urgently needed to meet humanity's growing needs. Solar energy, as a clean energy source with enormous energy reserves, has begun to attract attention and be utilized. Currently, silicon-based solar cell devices are commercialized, but they also have many shortcomings, requiring a new material to address these deficiencies. As a new optoelectronic material, perovskite has experienced rapid development in this context. Its many advantages, such as tunable bandgap, long carrier diffusion length, lightweight, and simple fabrication methods, have made it highly sought after. In the past decade or so, the photoelectric conversion efficiency of perovskite solar cells has improved rapidly, from an initial 3.8% to over 26%, comparable to commercial silicon-based solar cells. However, the stability of perovskite solar cells remains a major obstacle to their commercialization.

[0003] Because perovskite is an ionic crystal, the interactions between its components are much weaker than covalent bonds, making it highly susceptible to degradation due to environmental factors. For example, water in the environment can induce rapid degradation of perovskite crystals, leading to a rapid decline in device performance. Currently, researchers have employed various methods to overcome this problem, such as isolating the device from the environment through post-construction encapsulation to reduce the impact of moisture, or introducing additives to the perovskite to increase its stability. Summary of the Invention

[0004] One of the objectives of this invention is to provide a method for preparing perovskite-polymer thin films, which uses unsaturated monomers as additives to introduce into the perovskite, thereby improving the performance and enhancing the stability of perovskite solar cells.

[0005] The second objective of this invention is to provide a perovskite solar cell with superior device performance and strong stability.

[0006] One of the solutions adopted to achieve the objective of this invention is: a method for preparing a perovskite-polymer thin film, comprising the following steps: (1) Prepare ABX3 type perovskite precursor solution; (2) Prepare a mixture of low-boiling-point unsaturated monomer and initiator; and add it to the precursor solution prepared in step (1), and stir until the reaction is complete; (3) After the solution from step (2) has been completely reacted, it is filtered and coated onto the substrate surface. After annealing, the perovskite-polymer film is obtained.

[0007] Preferably, in step (1), the unsaturated monomer is at least one of ethyl acrylate (EA), methyl acrylate, styrene acrylate (PEA), n-propyl acrylate, and isopropyl acrylate.

[0008] Preferably, in step (1), the initiator is at least one of azobisisobutyronitrile (AIBN), benzoyl peroxide (BPO), and azobisisoheptanenitrile (ABVN).

[0009] Preferably, in step (1), the content of the initiator relative to the unsaturated monomer is 0.1wt%-1.5wt%.

[0010] Preferably, in step (1), the content of the initiator relative to the unsaturated monomer is 0.5 wt%.

[0011] Preferably, in step (2), the amount of mixed solution added is 0.1-30 μl / ml.

[0012] Preferably, in step (2), the A-site cation in the ABX3 perovskite is a formamidinium ion (FA). + Cesium ions (Cs) + and methylamine ions MA + The formamidinium ion FA + The molar percentage of cations at site A is 79%. 95%, cesium ions (Cs) + The molar percentage of the total A-site cations is 0. 10%, methylamine ion MA + The molar percentage of the total A-site cations is 0. 16%.

[0013] Preferably, in step (2), X in the ABX3 type perovskite is Br. and I , of which Br The molar percentage of X in the total content is 0. 40%, with a balance of I - The B-site ion is a lead ion (Pb). 2+ .

[0014] Preferably, in step (2), the ABX3 perovskite precursor solution is prepared by a solution method, using a dimethyl sulfoxide and N,N ratio of 1:4 by volume as the solvent. A mixture of dimethylformamide; the concentration of the perovskite component in the perovskite precursor solution is 1M–1.6M.

[0015] Preferably, in step (3), the annealing temperature is 100°C.

[0016] The second objective of this invention is achieved by providing a perovskite solar cell, comprising a perovskite-polymer thin film prepared by the aforementioned method.

[0017] Currently, additives used to regulate perovskite crystallization fall into two main categories: small molecule additives and polymer additives. Small molecule additives are readily soluble, offering a wider selection of solutions. They also diffuse more easily in solution, thus reducing the steric hindrance affecting their interaction with perovskite components. However, due to their relatively small molecular weight, small molecules tend to be less stable. Polymer additives, on the other hand, have much higher stability due to their larger molecular weight. However, their larger molecular weight makes them more difficult to dissolve, requiring specific solvents and resulting in lower solubility. Furthermore, the functional groups of polymers exhibit greater steric hindrance due to the influence of the main chain, further restricting their interaction with perovskite components in solution. Therefore, adding polymers as additives to perovskite solutions faces more limitations compared to small molecule additives.

[0018] The interaction between unsaturated monomers and perovskite components improves the crystallinity of the perovskite. Simultaneously, during crystallization annealing, the unsaturated monomers undergo in-situ polymerization in the presence of an initiator, resulting in polymers present on the perovskite film and at the interfaces. The improved crystallinity of the perovskite film and the passivation effect of the polymer enhance the performance of the perovskite solar cell device. Furthermore, the hydrophobicity of the polymer mitigates the impact of atmospheric moisture on the perovskite film, enhancing the humidity stability of the perovskite solar cell device.

[0019] In this invention, the unsaturated monomers selected have low boiling points, below the annealing temperature. The annealing temperature of perovskite crystallization is sufficient to allow the unpolymerized monomers to completely volatilize, avoiding monomer residue. This results in only polymer residue remaining in the perovskite film after annealing, producing passivation and hydrophobic effects. This can be used to improve the performance of perovskite solar cell devices and enhance the stability of the devices.

[0020] The present invention has the following advantages and beneficial effects: In this invention, unsaturated monomers are used as additives. Before polymerization, these monomers are small molecules, easily soluble, and diffuse more readily in solution. This reduces the steric hindrance affecting their interaction with perovskite components. However, during perovskite crystallization, in-situ polymerization transforms the unsaturated monomers into polymers, which possess the stability of polymers. Furthermore, their hydrophobicity increases the stability of perovskite against airborne water molecules. Therefore, the unsaturated monomer additive combines the characteristics of both small molecules and polymers, improving the performance and stability of perovskite solar cell devices. Attached Figure Description

[0021] Figure 1 This is a performance graph showing the addition of different amounts of the unsaturated monomer additive EA to perovskite. Figure 1 In this context, 'a' represents the change in the device's open-circuit voltage (Voc) with the EA content. Figure 1 In the figure, b represents the change in the short-circuit current (Jsc) of the device with the EA content. Figure 1 In this context, 'c' represents the change in the fill factor (FF) as a function of EA content. Figure 1 In the figure, d represents the change in photoelectric conversion efficiency (PCE) with the content of EA; Figure 2 These are performance graphs of perovskite with different amounts of the initiator AIBN. Figure 2 In the diagram, 'a' represents the change in Voc of the device with the AIBN content. Figure 2 In the figure, b represents the change of Jsc of the device with the content of EA. Figure 2 c represents the change of FF with AIBN content. Figure 2 In the middle, d represents the change in PCE with AIBN content; Figure 3 This is a performance graph showing the addition of different amounts of the unsaturated monomer additive PEA to perovskite. Figure 3 In the figure, 'a' represents the change in Voc of the device with the PEA content. Figure 3 In the figure, b represents the change of Jsc of the device with PEA content. Figure 3 c represents the change of FF with PEA content. Figure 3 In the figure, d represents the change in PCE with PEA content; Figure 4 These are actual images of perovskite films with different amounts of EA and AIBN added, before and after aging in an environment with 85% humidity. Figure 5 These are UV-Vis spectra of perovskite films with varying amounts of EA and AIBN aged in an 85% humidity environment. Figure 5 In Figure 'a', the UV-Vis spectrum of the perovskite film of sample 'control' changes over time in an environment with 85% humidity. Figure 5Figure b shows the UV-Vis spectrum of the perovskite film of sample AIBN-0 over time in an environment with 85% humidity. Figure 5 In the image, c represents the UV-Vis spectrum of the perovskite film of sample EA-5 over time in an environment with 85% humidity. Figure 5 In the image, d is the UV-Vis spectrum of the perovskite film of sample EA-30 over time in an environment with 85% humidity. Figure 6 This is the maximum power point output (MPP) curve of the unpackaged device in the environment. Detailed Implementation

[0022] To better understand the present invention, the following embodiments are further illustrations of the present invention, but the content of the present invention is not limited to the following embodiments.

[0023] Example 1 A pin-structured perovskite solar cell device with the structure of FTO / NiO / Me-4PACz / perovskite layer / C 60 / BCP / Cu, wherein the perovskite layer is prepared by a method using FA as the formulation component. 0.9 MA 0.06 Cs 0.04 A 1.45 M PbI3 perovskite solution was prepared with DMSO and DMF (volume ratio DMSO: DMF = 1:4) and stirred overnight in a glove box. Before filtration, a mixed solution of EA and AIBN (AIBN content relative to EA was 0.5 wt%) was prepared. 5 μl of the EA and AIBN mixture was then added to 1 ml of the perovskite solution and stirred. After half an hour, the solution was filtered, spin-coated, and then annealed at 100 °C for 1 h to obtain the sample named EA-5. Its performance graph is shown below. Figure 1 The average power conversion efficiency (PCE) of the device was 25.14%, an improvement over the control device. During aging in an air environment with 85% relative humidity, the UV-Vis spectrum of the perovskite showed... Figure 5 As aging time increased, the absorption of the perovskite film decreased slightly, indicating slight degradation of the film under this humidity environment. Maximum power point output (MPP) was then tested by placing the unencapsulated device in air. Figure 6 With a relative humidity of 55%-60% and a temperature of approximately 45℃, it can be observed that the photoelectric conversion performance of the EA-5 device decreased to 90% of its initial value after approximately 256 hours of aging. 90 Compared to the slower degradation of control devices, stability has been enhanced.

[0024] Example 2 Pin-structured perovskite solar cell devices have a structure of FTO / NiO / Me-4PACz / perovskite layer / C 60 The / BCP / Cu perovskite layer is prepared by using FA as the formulation component. 0.9 MA 0.06 Cs 0.04 A 1.45 M PbI3 perovskite solution was prepared using DMSO and DMF (volume ratio DMSO: DMF = 1:4) and stirred overnight in a glove box. Before filtration, a mixed solution of EA and AIBN (AIBN content relative to EA was 0.5 wt%) was prepared. 30 μl of this EA and AIBN mixture was then added to 1 ml of the perovskite solution and stirred. After half an hour, the solution was filtered, spin-coated, and annealed at 100 °C for 1 h to obtain the sample, named EA-30. Its performance is shown in the figure below. Figure 1 The average power conversion efficiency (PCE) of the device is 22.78%. A physical image of the perovskite thin film is shown below. Figure 4 It can be observed that in an air environment with a relative humidity of 85%, the film was smooth and black before aging. After 48 hours of aging, the edges of the perovskite film showed slight degradation and turned yellow. This can be seen from the UV-Vis spectrum of the perovskite film. Figure 5 As the aging time changed, the absorption of the perovskite film remained basically unchanged, indicating that the degradation rate of the film under this humidity environment was slower than that of the control sample, and the stability of the film was enhanced.

[0025] Example 3 Pin-structured perovskite solar cell devices have a structure of FTO / NiO / Me-4PACz / perovskite layer / C 60 The / BCP / Cu perovskite layer is prepared by using FA as the formulation component. 0.9 MA 0.06 Cs 0.04 A 1.45 M PbI3 perovskite solution was prepared with DMSO and DMF (volume ratio DMSO:DMF = 1:4) and stirred overnight in a glove box. Before filtration, a mixed solution of EA and AIBN (AIBN content relative to EA was 1.5 wt%) was prepared. 5 μl of the EA and AIBN mixture was then added to 1 ml of the perovskite solution and stirred. After half an hour, the solution was filtered, spin-coated, and annealed at 100 °C for 1 h to obtain a sample named AIBN-1.5. Its performance is shown in the figure below. Figure 2 The average power conversion efficiency (PCE) of the device is 24.23%.

[0026] Example 4 Pin-structured perovskite solar cell devices have a structure of FTO / NiO / Me-4PACz / perovskite layer / C 60 The / BCP / Cu perovskite layer is prepared by using FA as the formulation component. 0.9 MA 0.06 Cs 0.04 A 1.45 M PbI3 perovskite solution was prepared using DMSO and DMF (volume ratio DMSO:DMMF = 1:4) and stirred overnight in a glove box. Before filtration, a mixed solution of EA and AIBN (AIBN content relative to EA was 0.5 wt%) was prepared. 15 μl of this EA and AIBN mixture was then added to 1 ml of the perovskite solution and stirred. After half an hour, the solution was filtered, spin-coated, and annealed at 100 °C for 1 h to obtain the sample, named EA-15. Its performance is shown in the figure below. Figure 1 The average power conversion efficiency (PCE) of the device is 24.46%.

[0027] Example 5 Pin-structured perovskite solar cell devices have a structure of FTO / NiO / Me-4PACz / perovskite layer / C 60 The / BCP / Cu perovskite layer is prepared by using FA as the formulation component. 0.9 MA 0.06 Cs 0.04 A 1.45 M PbI3 perovskite solution was prepared with DMSO and DMF (volume ratio DMSO:DMF = 1:4) and stirred overnight in a glove box. Before filtration, a mixed solution of EA and AIBN (AIBN content relative to EA was 0.25 wt%) was prepared. 5 μl of the EA and AIBN mixture was then added to 1 ml of the perovskite solution and stirred. After half an hour, the solution was filtered, spin-coated, and annealed at 100 °C for 1 h to obtain a sample named AIBN-0.25. Its performance is shown in the figure below. Figure 2 The average power conversion efficiency (PCE) of the device is 24.88%.

[0028] Example 6 Pin-structured perovskite solar cell devices have a structure of FTO / NiO / Me-4PACz / perovskite layer / C 60 The / BCP / Cu perovskite layer is prepared by using FA as the formulation component. 0.79 MA 0.15 Cs 0.05 PbI 2.7 Br 0.3A 1.35 M perovskite solution was prepared with DMSO and DMF (volume ratio DMSO: DMF = 1:4) and stirred overnight in a glove box. Before filtration, a mixed solution of styrene acrylate (PEA) and azobisisobutyronitrile (ABVN) (ABVN content relative to PEA was 0.5 wt%) was prepared. Then, 5 μl of the PEA and ABVN mixture was added to 1 mL of the perovskite solution and stirred. After half an hour, the solution was filtered, spin-coated, and then annealed at 100 °C for 1 h to obtain the sample named PEA-5. Its performance is shown in the figure below. Figure 3 The average power conversion efficiency (PCE) of the device is 22.9%. Figure 3 The pattern shows that as the PEA content increases, the device performance first rises and then falls, exhibiting the same trend as the change in EA content.

[0029] Comparative Example 1 Pin-structured perovskite solar cell devices have a structure of FTO / NiO / Me-4PACz / perovskite layer / C 60 The / BCP / Cu perovskite layer is prepared by using FA as the formulation component. 0.9 MA 0.06 Cs 0.04 A 1.45 M PbI3 perovskite solution was prepared using DMSO and DMF (volume ratio DMSO:DMMF = 1:4) as a mixed solvent. The solution was stirred overnight in a glove box, filtered, spin-coated, and then annealed at 100 °C for 1 h. The resulting sample was named "control," and its performance is shown in the figure. Figure 1 The average power conversion efficiency (PCE) of the device is 23.91%. A physical image of the perovskite thin film is shown below. Figure 4 It can be observed that in an air environment with a relative humidity of 85%, the film was smooth and black before aging. After 48 hours of aging, the perovskite film partially degraded and turned yellow. Furthermore, the UV-Vis spectrum of the aged film shows... Figure 5 As aging time increased, the absorption of the perovskite film gradually decreased, indicating that the film degraded under this humidity environment. Maximum power point output (MPP) was then tested by placing the unencapsulated device in air. Figure 6 With a relative humidity of 55%-60% and a temperature of approximately 45℃, it can be observed that the photoelectric conversion performance of the control device decreased to 80% of its initial value after approximately 75 hours of aging. 80 ).

[0030] Comparative Example 2 Pin-structured perovskite solar cell devices have a structure of FTO / NiO / Me-4PACz / perovskite layer / C60 The / BCP / Cu perovskite layer is prepared by using FA as the formulation component. 0.9 MA 0.06 Cs 0.04 A 1.45 M PbI3 perovskite solution was prepared with DMSO and DMF (volume ratio DMSO:DMMF = 1:4) and stirred overnight in a glove box. Before filtration, a mixed solution of EA and AIBN (AIBN content relative to EA was 0%) was prepared. 5 μl of this EA and AIBN mixture was then added to 1 ml of the perovskite solution and stirred. After half an hour, the solution was filtered, spin-coated, and annealed at 100 °C for 1 hour to obtain a sample named AIBN-0. Its performance is shown in the figure below. Figure 2 The average power conversion efficiency (PCE) of the device is 24.43%. A physical image of the perovskite thin film is shown below. Figure 4 It can be observed that in an air environment with a relative humidity of 85%, the film was smooth and black before aging. After 48 hours of aging, a small amount of degradation appeared at the edges of the perovskite film, turning it yellow. This can be seen from the UV-Vis spectrum of the perovskite film. Figure 5 As the aging time changed, the absorption of the perovskite film gradually decreased, but the rate of decrease was slower than that of the control sample, indicating that the film degraded at a slower rate under this humidity environment than the control sample, and the stability of the film was enhanced.

[0031] Comparative Example 3 Pin-structured perovskite solar cell devices have a structure of FTO / NiO / Me-4PACz / perovskite layer / C 60 The / BCP / Cu perovskite layer is prepared by using FA as the formulation component. 0.79 MA 0.15 Cs 0.05 PbI 2.7 Br 0.3 A 1.35 M perovskite solution was prepared using a mixed solvent of DMSO and DMF (volume ratio DMSO: DMF = 1:4) and stirred overnight in a glove box. The solution was filtered, spin-coated, and then annealed at 100 °C for 1 h to obtain a sample named PEA-0. Its performance is shown in the figure below. Figure 3 The average power conversion efficiency (PCE) of the device is 22.69%.

[0032] The above description is merely a preferred embodiment of the present invention, and should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for preparing a perovskite-polymer thin film, characterized in that, Includes the following steps: (1) Prepare ABX3 type perovskite precursor solution, in which the A-site cation in ABX3 type perovskite is formamidinium ion (FA). + Cesium ions (Cs) + and methylamine ions MA + X is Br - and I - The B-site ion is a lead ion (Pb). 2+ ; (2) Prepare a mixture of low-boiling-point unsaturated monomer and initiator; and add it to the precursor solution prepared in step (1), and stir until the reaction is complete. The unsaturated monomer is at least one of ethyl acrylate and methyl acrylate, and the boiling point of the low-boiling-point unsaturated monomer is lower than the annealing temperature. (3) After the solution from step (2) is completely reacted, it is filtered and coated onto the substrate surface. After annealing, the perovskite-polymer film is obtained. During the crystallization annealing process, the unsaturated monomers undergo in-situ polymerization in the presence of an initiator.

2. The method for preparing perovskite-polymer thin films according to claim 1, characterized in that: In step (2), the initiator is at least one of azobisisobutyronitrile, benzoyl peroxide, and azobisisoheptanenitrile.

3. The method for preparing perovskite-polymer thin films according to claim 1, characterized in that: In step (2), the content of the initiator relative to the unsaturated monomer is 0.1wt%-1.5wt%.

4. The method for preparing perovskite-polymer thin films according to claim 1, characterized in that: In step (2), the amount of mixture added is 0.1-30 μl / ml.

5. The method for preparing perovskite-polymer thin films according to claim 1, characterized in that: In step (1), the formamidinium ion FA + The molar percentage of cesium ions (Cs) at the A site is 79%-95% of the total cations. + The molar percentage of the total A-site cations is 0-10%, and the methylamine ion (MA) is... + The molar percentage of the total A-site cations is 0-16%.

6. The method for preparing perovskite-polymer thin films according to claim 1, characterized in that: In step (1), Br - The molar percentage of X in the total content is 0-40%, with the remainder being I. - .

7. The method for preparing perovskite-polymer thin films according to claim 1, characterized in that: In step (1), the ABX3 perovskite precursor solution is prepared by solution method. The solvent used is a mixture of dimethyl sulfoxide and N,N-dimethylformamide in a volume ratio of 1:

4. The concentration of the perovskite component in the perovskite precursor solution is 1M–1.6M.

8. The method for preparing perovskite-polymer thin films according to claim 1, characterized in that: In step (3), the annealing temperature is 100°C.

9. A perovskite solar cell, characterized in that: The perovskite-polymer film prepared by the preparation method according to any one of claims 1-8.

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