Preparation method for multilayer composite packaging of perovskite solar cell

Abstract

The invention discloses a preparation method for multilayer composite packaging of a perovskite solar cell, and belongs to the technical field of solar photovoltaics. The perovskite solar cell protection layer is prepared through blade coating, slit coating, spraying, ink-jet printing, silk-screen printing and the like, the short-circuit current density is increased by optimizing the utilization rate of light, the cell performance is improved, the preparation mode is simpler, the method is suitable for large-area batch production, and the cost is lower. Because the temperature in the preparation process is low, thermal damage of the perovskite material can be effectively avoided, the lattice stability is effectively maintained, the lead leakage risk is reduced, thermal expansion coefficient mismatch between the layers of materials is reduced, and interface layering or fracture is avoided, so that the assembly yield is improved. In addition, a multi-layer structure can be adopted for packaging, the barrier property, the mechanical strength, the photoelectric efficiency, the environmental adaptability and the like are comprehensively improved through the synergistic effect of different functional materials, multi-layer packaging develops towards the ultrathin, intelligent and low-cost direction, and the application boundary of the perovskite solar cell is further expanded.

Description

Technical Field

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

[0002] With the ever-increasing energy demand of human society and the dwindling supply of traditional fossil fuels, a major challenge for the future is finding a renewable energy source to replace traditional fossil fuels. Solar energy, with its inexhaustible, environmentally friendly characteristics, has gained significant attention. Currently, silicon-based solar cells dominate the market, but due to their high manufacturing costs and complex processes, their ability to become a primary clean energy source for humanity in the future is constantly questioned. Therefore, it is essential to find new types of solar cells that are inexpensive and have simple manufacturing processes. Since 2009, new solar cells based on organic-inorganic perovskite materials have attracted widespread attention.

[0003] Perovskite solar cells have attracted widespread attention from academia and industry due to their high photoelectric conversion efficiency under low light, strong light absorption, and versatility in various applications. However, the Pb-I bonds in perovskite materials are susceptible to decomposition due to factors such as water, oxygen, light, and high temperatures. Encapsulation can effectively address these issues. Currently, the most commonly used encapsulation process is vacuum lamination technology using photovoltaic-grade ethylene-vinyl acetate (EVA) encapsulation films. However, substances such as acetic acid produced during long-term use of EVA films can react with perovskite, and the degradation of small molecules like acetic acid can lead to decreased material transparency. Furthermore, the high-temperature lamination process has a certain impact on perovskite. Therefore, developing a simple and low-cost encapsulation solution is crucial for the industrialization of perovskite photovoltaics. Summary of the Invention

[0004] This patent describes a method for preparing a protective layer for perovskite solar cells. Addressing the complexity of existing perovskite cell encapsulation processes and the impact of high-temperature lamination on perovskite lifespan, this patent designs a method using necessary equipment from the perovskite preparation process to prepare a protective layer for the surface of perovskite solar cells. By selecting methods such as blade coating, slot coating, spraying, inkjet printing, and screen printing to prepare the protective layer film, the operation is not only simple, but the resulting film has a suitable thickness, good light transmittance, and can effectively improve the energy conversion efficiency of the cell while suppressing ion diffusion between the electrode and the perovskite.

[0005] This invention provides a method for preparing a multilayer composite encapsulation of a perovskite solar cell. The cell sequentially includes a conductive substrate or a common substrate with a conductive thin film, a charge transport layer 1, a perovskite light-absorbing layer, a charge transport layer 2, a thin-film electrode, and at least two protective layers. The protective layers are made of different materials or the same material at different concentrations. The precursors for the protective layers include: polyolefin elastomer (POE) dispersion, polyvinyl butyral (PVB) dispersion, fluorocarbon resin dispersion, and ethylene-tetrafluoroethylene (ETFE) dispersion. The protective layers are prepared by methods such as blade coating, slot coating, spraying, inkjet printing, or screen printing.

[0006] Preferably, the charge transport layer 1 or the charge transport layer 2 is a hole transport layer or an electron transport layer.

[0007] Preferably, a conductive film is added to a common substrate, which is a transparent conductive film covered on glass. The transparent conductive film is one of fluorine-doped tin oxide (FTO), indium tin oxide (ITO), or zinc oxide doped (AZO, BZO, GZO, AGZO, etc.).

[0008] Preferably, the conductive substrate is FTO glass, ITO glass, stainless steel foil, or a polymer covered with a metal thin film; the hole transport layer is NiO. X x is 0.95-1.05; the electron transport layer is fullerene or its derivative, copper bath (BCP), zinc oxide, tin oxide or a combination thereof; the thin film electrode layer is one of the following: metal thin film (such as aluminum, nickel, chromium, silver, copper, gold, etc.) or conductive metal oxide such as ITO, FTO, AZO, etc.

[0009] Preferably, 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, when x=1 and a=1 it is CsPbI3; when y=1 and a=1 it is MAPbI3; when z=1 and a=1 it is FAPbI3, or a portion thereof Cs 、 MA and FA can be replaced by alkali metals accounting for less than 10% of their respective metal weight content; the alkali metals include lithium (Li), sodium (Na), potassium (K), rubidium (Rb), francium (Fr) or alkaline earth metals beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).

[0010] This invention provides a method for preparing the above-mentioned multilayer composite encapsulation of perovskite solar cells. A protective layer dispersion is coated on the perovskite solar cell, purged with compressed air, dried, annealed, and then a second protective layer is coated in the same manner after drying. The precursor concentration of the second protective layer is higher than that of the first layer. The complete perovskite solar cell is prepared by purging with compressed air, drying, and annealing.

[0011] Preferably, the drying temperature is 30-50℃; the annealing temperature is 100-150℃; and the annealing time is 10-30 minutes.

[0012] Preferably, the thickness of the protective layer dispersion on the perovskite solar cell is 1-100 μm.

[0013] Preferably, the method for preparing the protective layer dispersion in the step is as follows: Polyolefin elastomer dispersion: POE particles are thoroughly ground and added to a mixed solution of tetrahydrofuran and ethyl acetate. Antistatic agents and coupling agents are added, the mixture is heated and stirred, cooled, and then filtered. The filtration pore size is ≤0.5μm. The solid content of the dispersion is 5-20 Wt%. Polyvinyl butyral dispersion: PVB particles are thoroughly ground, and 60% ethanol is added. The mixture is heated and stirred at 50-60℃ for 2-4 hours until the PVB is completely dissolved, yielding a clear, viscous PVB solution. 40% deionized water and a weighed surfactant (0.1%-1% of the total amount) are added, and stirring is started to ensure complete dissolution. The PVB solution is then added to the water and stirred thoroughly to form a stable, milky-white dispersion. The solid content of the dispersion is 5-20 wt%. Fluorocarbon resin dispersion: Fluorine-containing soft monomers and fluorine-containing hard monomers are selected in a weight ratio of 3:1. Under inert gas protection, the monomer mixture of fluorine-containing soft / hard monomers and initiator is slowly added dropwise to preheated ethylene glycol monobutyl ether or propylene glycol monobutyl ether solvent. The temperature is controlled at 110-125℃, and the dropwise addition time is 4-5 hours. Then, the reaction is kept at this temperature for 2-3 hours. The initiator is added in two batches at a dosage of 2%-5% of the total monomers to ensure that the polymerization reaction occurs fully. The temperature is lowered to 50-70℃, and the solvent and impurities are removed by vacuum distillation (the resin mass fraction must be >85%). Finally, water is added and emulsified by high-speed stirring to form an aqueous dispersion. Ethylene-tetrafluoroethylene dispersion: Grind ETFE particles thoroughly, add ETFE resin, leveling agent, and curing agent to DMF and stir thoroughly at 30-35℃ to ensure uniform dispersion, and obtain ETFE dispersion; the solid content of ETFE solution is controlled at 5-20%.

[0014] Preferably, in the preparation of the fluorocarbon resin dispersion, the initiator is selected from tert-butyl peroxide or tert-butyl peroxide.

[0015] Preferably, POE particles are thoroughly ground (the solid content of the POE solution is usually controlled at 5-20%), added to a mixed solution of tetrahydrofuran (60%) and ethyl acetate (40%), and additives (0.5% TMACL antistatic agent + 1% KH550 coupling agent) are added. The mixture is heated and stirred at 80°C for 2 hours, cooled, and then filtered. The filtered solution (pore size ≤ 0.5 μm) is then coated to form a protective layer.

[0016] Preferably, a method for fabricating a perovskite solar cell includes the following specific fabrication process: (1) Clean the substrate.

[0017] (2) An ITO functional layer is prepared on a substrate using magnetron sputtering.

[0018] (3) A NiOx transport layer is prepared on a conductive substrate / ITO using magnetron sputtering.

[0019] (4) Using the blade coating method, the perovskite precursor solution is blade coated onto the conductive substrate / ITO / empty NiOx, and after annealing, a perovskite light-absorbing layer is formed.

[0020] (5) Using a blade coating / evaporation method, an electron transport layer is prepared on a conductive substrate / ITO / NiOx / PVK to prepare a PCBM / ZnO or C60 / BCP.

[0021] (6) ITO transparent electrodes and metal electrodes were prepared by sputtering / evaporation to obtain perovskite solar cells.

[0022] (7) Using any one of the following methods, such as scraping, slot coating, spraying, screen printing, inkjet printing, etc., hydrophobic substances such as polyolefin elastomer (POE) dispersion, polyvinyl butyral (PVB) dispersion, fluorocarbon resin dispersion, and ethylene-tetrafluoroethylene (ETFE) dispersion are coated on the surface of the battery to prepare a perovskite solar cell, forming a first protective layer. After the protective layer is completely cured, a second protective layer is prepared in the same way, with the concentration of the second layer solution being higher than that of the first layer.

[0023] The conductive substrate in step (1) can be FTO glass, ITO glass, or stainless steel foil, metal film-covered polymer, etc.

[0024] In step (2), the chamber is evacuated to a vacuum level less than 2.0 × 10⁻⁶. -4 At 20 sccm, an Ar / O2 mixture (Ar:O2 = 95:5) is introduced. After the vacuum level in the chamber stabilizes, ITO is sputtered to a thickness of 100 nm-200 nm.

[0025] In step (3), the chamber is evacuated to a vacuum level less than 2.0 × 10⁻⁶. -4 Pa, 12 sccm of Ar / O2 mixed gas (Ar:O2 = 95:5) and 8 sccm of O2 are introduced. After the vacuum in the chamber stabilizes, NiOx is sputtered to prepare a hole transport layer with a thickness of 20nm-100nm.

[0026] The organic perovskite precursor in step (4) includes, but is not limited to, 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, when x=1, a=1 it is CsPbI3; when y=1, a=1 it is MAPbI3; when z=1, a=1 it is FAPbI3, where part of Cs 、 MA and FA can be replaced with small amounts (less than 10%) of alkali metals including lithium (Li), sodium (Na), potassium (K), rubidium (Rb), francium (Fr) or alkaline earth metals such as beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). The solution concentration is 0.6 M - 1.5 M, the annealing temperature of the perovskite layer is 70 ℃ - 350 ℃, the annealing time is 1 min - 1000 min, and the thickness is 200 nm - 600 nm.

[0027] In step (5), the electron transport layer can be prepared by the blade coating method using PCBM or ZnO, and the electron transport layer can be prepared by the vapor deposition method using C. 60 BCP, with a thickness of 10nm-200nm.

[0028] In step (6), the electrodes can be metal thin films (such as aluminum, nickel, chromium, silver, copper, gold, etc.) or conductive metal oxides such as ITO, FTO, AZO, etc., with a thickness of 100nm-300nm.

[0029] The protective layer in step (7) can be prepared by any of the following methods: scraping, slot coating, spraying, screen printing, inkjet printing, etc. Hydrophobic substances such as polyolefin elastomer (POE) dispersion, polyvinyl butyral (PVB) dispersion, fluorocarbon resin dispersion, and ethylene-tetrafluoroethylene (ETFE) dispersion are prepared on the battery surface with a thickness of 1-100 μm.

[0030] This patent 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.

[0031] The advantages of this invention compared to existing methods are as follows: (1) In practical applications, protective layers prepared by methods such as scraping, slot coating, spraying, screen printing, and inkjet printing have moderate film thickness and higher light transmittance, which can effectively increase the short-circuit current density (JSC) of perovskite solar cells. By optimizing the utilization of light, the performance of the cells can be improved, and the preparation method is simpler, making it suitable for large-area mass production and lower cost.

[0032] (2) The perovskite solar cells encapsulated using the present invention can effectively avoid thermal damage to perovskite materials. Low-temperature encapsulation can effectively maintain lattice stability and reduce the risk of lead leakage. Low-temperature process can reduce the mismatch of thermal expansion coefficients between materials of each layer, effectively avoid interface delamination or breakage, thereby improving the yield of the module.

[0033] (3) Perovskite solar cells encapsulated using the present invention can be encapsulated in a multi-layer structure because the thickness of the prepared thin film is better controlled. Through the synergistic effect of different functional materials, the barrier properties, mechanical strength, photoelectric efficiency and environmental adaptability are comprehensively improved. Multi-layer encapsulation can develop towards ultra-thinness, intelligence and low cost, further expanding the application boundaries of perovskite solar cells. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the protective layer perovskite solar cell structure prepared in Example 1 of this application; Figure 2 A schematic diagram of the water contact angle of the perovskite solar cell prepared in Comparative Example 2 without a hydrophobic protective layer. Figure 3 A schematic diagram of the water contact angle of a hydrophobic protective layer in a perovskite solar cell prepared in Comparative Example 1. Figure 4 This is a schematic diagram of the water contact angle of the two hydrophobic protective layers of the perovskite solar cell prepared in Example 1 of this application. Detailed Implementation

[0035] 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.

[0036] Example 1 Cleaning the substrate: Clean the conductive substrate with alkaline solution and deionized water and dry it for later use.

[0037] Fabrication of the ITO functional layer: Using magnetron sputtering, the cleaned substrate was placed into the chamber, and the chamber was evacuated to a vacuum level of less than 2.0 × 10⁻⁶. -4At 20 sccm, an Ar / O2 mixture (Ar:O2 = 95:5) was introduced, with a power of 200 W, a working pressure of 5 mTorr, and a rotation speed of 0.4 rpm, to sputter an ITO functional layer on the surface of a conductive substrate. Charge transport layer 1 was prepared as a NiOx hole transport layer, with x ranging from 0.95 to 1.05. A conductive substrate / ITO was placed in a chamber using magnetron sputtering, and the chamber was evacuated to a vacuum level less than 2.0 × 10⁻⁵. -4 The system was operated at 12 sccm of Ar / O2 mixture (Ar:O2 = 95:5) and 8 sccm of O2, with a power of 140 W, a working pressure of 2 mTorr, and a rotation speed of 0.4 rpm to sputter the hole transport layer. After the NiOx layer was prepared, the substrate was annealed and crystallized at 300 degrees Celsius for one hour. After the substrate cooled naturally, subsequent operations could be performed.

[0038] Perovskite light-absorbing layer coating: After annealing, a perovskite thin film sample prepared on a conductive substrate / ITO / NiOx substrate was obtained. A perovskite precursor solution was then coated onto the sample surface using a 200 μm slit, a travel speed of 0.3 m / min, and a feed rate of 250 rpm. Extraction was performed using a 0.8 MPa air knife. The completed sample was then annealed at 110 degrees Celsius for 30 min.

[0039] Preparation of Charge Transport Layer 2: A conductive substrate / ITO / NiOx / PVK sample was obtained through the above steps, where x ranges from 0.95 to 1.05. An electron transport layer (PCBM) was then coated onto the sample surface using a 150 μm slit, a travel speed of 0.4 m / min, a feed rate of 250 rpm, and an air knife pressure of 0.1 MPa. After the electron transport layer was prepared, a 2.5 wt% zinc oxide nanoparticle isopropanol dispersion was coated onto the electron transport layer surface as a protective barrier layer using the same process. After coating, the sample was annealed at 100°C for 10 min.

[0040] Preparation of ITO electrode: The sample prepared according to the above steps was placed in a magnetron sputtering system to sputter a 200 nm ITO transparent electrode. The background vacuum was 20 mTorr, the power was 180 W, the rotation speed was 0.2 rpm, the working gas pressure was 5 mTorr, and 20 sccm of Ar / O2 mixed gas (Ar:O2 = 95:5) was introduced.

[0041] Preparation of the protective layer: After the above steps, we obtained the perovskite solar cell. A hydrophobic dispersion was coated onto the cell surface using a blade coating method to form the first protective layer. This was followed by compressed air blowing, drying, and annealing. After drying, a second protective layer was coated in the same manner. The concentration of the dispersion in the second protective layer was higher than that in the first layer (10 wt%, 15 wt%). The complete perovskite solar cell was prepared by compressed air blowing, drying, and annealing. The drying temperature for the first layer was 40℃; the annealing temperature was 110℃ for 15 min. The drying temperature for the second layer was 40℃; the annealing temperature was 150℃ for 20 min. The concentration of the POE dispersion in the first layer was 10 wt%; the concentration of the POE dispersion in the second layer was 15 wt%. The thickness of both protective layers was controlled at 5 μm.

[0042] The following is the method for preparing the hydrophobic layer solution: Polyolefin elastomer (POE) dispersion: POE particles are thoroughly ground (the solid content of the POE solution is usually controlled at 5-20%) and added to a mixed solution of tetrahydrofuran:ethyl acetate = 60:40 (volume ratio). Additives (0.5% TMACL antistatic agent + 1% KH550 coupling agent) are added (based on the total mass of the dispersion). The mixture is heated and stirred at 80°C for 2 hours, cooled, and then filtered. The filtered solution (pore size ≤ 0.5 μm) is the coating solution.

[0043] Example 2 The method for preparing the protective layer in Example 1 was changed from scraping to spraying, while the other operating conditions remained the same as in Example 1.

[0044] Example 3 The method for preparing the protective layer in Example 1 was changed from scraping to inkjet printing, while the other operating conditions remained the same as in Example 1.

[0045] Example 4 The method for preparing the protective layer in Example 1 was changed from scraping to screen printing, while the other operating conditions remained the same as in Example 1.

[0046] Example 5 The method for preparing the protective layer in Example 1 was changed from scraping to slot coating, while the other operating conditions remained the same as in Example 1.

[0047] Comparative Example 1 In Example 1, only one protective layer was prepared with a thickness controlled at 1-5 μm, and the remaining operating conditions were the same as in Example 1.

[0048] Comparative Example 2 The difference from Example 1 is that no protective layer is prepared.

Claims

1. A method for preparing a multilayer composite encapsulation for a perovskite solar cell, characterized in that: The perovskite solar cell sequentially comprises a conductive substrate or a common substrate with a conductive thin film, a charge transport layer 1, a perovskite light-absorbing layer, a charge transport layer 2, a thin-film electrode, and at least two protective layers. The protective layers are made of different materials or the same material at different concentrations. The protective layer dispersion includes: polyolefin elastomer dispersion, polyvinyl butyral dispersion, fluorocarbon resin dispersion, and ethylene-tetrafluoroethylene dispersion. The protective layer is prepared by methods such as blade coating, slot coating, spraying, inkjet printing, or screen printing.

2. The preparation method according to claim 1, characterized in that, The charge transport layer 1 or charge transport layer 2 is a type of hole transport layer or electron transport layer.

3. The preparation method according to claim 1, characterized in that, A common substrate with a conductive film is a transparent conductive film covered on glass. The transparent conductive film is one of fluorine-doped tin oxide, indium tin oxide, or zinc oxide.

4. The preparation method according to claim 1, characterized in that, The conductive substrate is a polymer covered by FTO glass, ITO glass, stainless steel foil, or a metal thin film; the hole transport layer is NiO. X x is 0.95–1.05; the electron transport layer is fullerene or its derivative, copper bath, zinc oxide, tin oxide or a combination thereof; the thin film electrode layer is a metal thin film or a conductive metal oxide such as ITO, FTO, AZO, etc.

5. The preparation method 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, when x=1 and a=1 it is CsPbI3; when y=1 and a=1 it is MAPbI3; when z=1 and a=1 it is FAPbI3, or a portion thereof Cs 、 MA and FA can be replaced by alkali metals accounting for less than 10% of their respective metal weight content; the alkali metals include lithium, sodium, potassium, rubidium, francium or alkaline earth metals beryllium, magnesium, calcium, strontium, barium, and radium.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The protective layer dispersion was coated onto the perovskite solar cell, purged with compressed air, dried, and annealed. After drying, a second protective layer was coated in the same manner. The concentration of the dispersion in the second protective layer was higher than that in the first layer. The perovskite solar cell was then prepared by purging with compressed air, drying, and annealing.

7. The preparation method according to claim 6, characterized in that: The drying temperature is 30-50℃; Annealing temperature is 100-150℃; annealing time is 10-30 minutes.

8. The thickness of the single layer of the protective layer dispersion on the perovskite solar cell is 1-100 μm.

9. The preparation method according to claim 6, characterized in that, The method for preparing the protective layer dispersion in the above step is as follows: Polyolefin elastomer dispersion: POE particles are thoroughly ground and added to a mixed solution of tetrahydrofuran and ethyl acetate. Antistatic agents and coupling agents are added, the mixture is heated and stirred, cooled, and then filtered. The filtration pore size is ≤0.5μm. The solid content of the dispersion is 5-20 wt%. Polyvinyl butyral dispersion: PVB particles are thoroughly ground, and 60% ethanol is added. The mixture is heated and stirred at 50-60℃ for 2-4 hours until the PVB is completely dissolved, yielding a clear, viscous PVB solution. 40% deionized water and a weighed surfactant (0.1%-1% of the total amount) are added, and stirring is started to ensure complete dissolution. The PVB solution is then added to the water and stirred thoroughly to form a stable, milky-white dispersion. The solid content of the dispersion is 5-20 wt%. Fluorocarbon resin dispersion: Fluorine-containing soft monomers and fluorine-containing hard monomers are selected in a weight ratio of 3:

1. Under inert gas protection, the monomer mixture of fluorine-containing soft / hard monomers and initiator is slowly added dropwise to preheated ethylene glycol monobutyl ether or propylene glycol monobutyl ether solvent. The temperature is controlled at 110-125℃, and the dropwise addition time is 4-5 hours. Then, the reaction is kept at this temperature for 2-3 hours. The initiator is added in two batches at a dosage of 2%-5% of the total monomers to ensure that the polymerization reaction occurs fully. The temperature is lowered to 50-70℃, and the solvent and impurities are removed by vacuum distillation (the resin mass fraction must be >85%). Finally, water is added and emulsified by high-speed stirring to form an aqueous dispersion. Ethylene-tetrafluoroethylene dispersion: Grind ETFE particles thoroughly, add ETFE resin, leveling agent, and curing agent to DMF and stir thoroughly at 30-35℃ to ensure uniform dispersion, and obtain ETFE dispersion; the solid content of ETFE solution is controlled at 5-20%.

10. The preparation method according to claim 8, characterized in that, In the preparation of fluorocarbon resin dispersions, the initiator is selected from tert-butyl peroxide or tert-butyl peroxyneodecanate.

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