Perovskite solar cell and preparation method of packaging material for perovskite solar cell

Abstract

The invention provides a perovskite solar cell and a preparation method of a packaging material for the perovskite solar cell, the perovskite solar cell comprises a cell body and a shell arranged on the outer surface of the cell body, the shell is sealed through a packaging layer, and the packaging layer comprises the packaging material; the packaging material comprises a modified HBN / epoxy resin composite material, the modified HBN is formed by compounding hexagonal boron nitride, polydopamine and chitosan, and the sealing performance of the perovskite solar cell can be improved, so that the long-term operation stability of the perovskite solar cell is improved, and industrial application of the perovskite solar cell is facilitated.

Description

Technical Field

[0001] This application relates to the field of solar cells, and more particularly to a perovskite solar cell and a method for preparing encapsulation materials for perovskite solar cells. Background Technology

[0002] Perovskite solar cells are devices that convert solar energy into electrical energy. They have excellent photoelectric properties and are simple in structure and low in manufacturing cost.

[0003] Although perovskite solar cells possess excellent photoelectric properties, these devices are susceptible to stability issues due to the influence of external moisture and oxygen, leading to a decrease in photoelectric conversion efficiency after long-term operation (e.g., 1000 hours). Improving the long-term operational stability of perovskite solar cells has become an urgent technical problem to be solved. Summary of the Invention

[0004] To address the aforementioned technical problems, this application discloses a perovskite solar cell and a method for preparing encapsulation materials for perovskite solar cells, thereby improving the long-term operational stability of perovskite solar cells.

[0005] In a first aspect, this application provides a perovskite solar cell, including a cell body and a housing disposed on the outer surface of the cell body, the housing being sealed by an encapsulation layer, the encapsulation layer including an encapsulation material;

[0006] The encapsulation material includes a modified HBN / epoxy resin composite material, wherein the modified HBN is composed of hexagonal boron nitride, polydopamine, and chitosan.

[0007] In some embodiments of this application, the modified HBN has a mass percentage content of 0.5% to 1.5% in the modified HBN / epoxy resin composite material, and the epoxy resin has a mass percentage content of 98.5% to 99.5% in the modified HBN / epoxy resin composite material.

[0008] In some embodiments of this application, the thickness of the encapsulation layer is 100 μm to 400 μm.

[0009] In some embodiments of this application, the weight-average molecular weight of the chitosan is 20,000 to 50,000.

[0010] In some embodiments of this application, the perovskite solar cell further includes an electrode extension that is electrically connected to the electrode of the cell body and extends from the encapsulation layer to the outside of the housing.

[0011] In some embodiments of this application, the photoelectric conversion efficiency of the perovskite solar cell decreases by no more than 5% after 1000 hours of operation.

[0012] In some embodiments of this application, the perovskite solar cell includes a single-junction perovskite solar cell or a perovskite tandem solar cell.

[0013] Secondly, this application provides a method for fabricating a solar cell as described in the first aspect, comprising the following steps:

[0014] Hexagonal boron nitride was added to a polydopamine solution to carry out the first crosslinking reaction, resulting in polydopamine crosslinked HBN.

[0015] Chitosan was added to the dispersion of the polydopamine-crosslinked HBN to carry out a second crosslinking reaction, thereby obtaining modified HBN.

[0016] The modified HBN is mixed with epoxy resin to obtain a modified HBN / epoxy resin composite material.

[0017] In some embodiments of this application, the reaction temperature of the first crosslinking reaction is 55°C to 65°C, and the reaction time is 20h to 30h.

[0018] In some embodiments of this application, the reaction temperature of the second crosslinking reaction is 100°C to 110°C, and the reaction time is 10h to 15h.

[0019] In some embodiments of this application, the modified HBN has a mass percentage content of 0.5% to 1.5% in the modified HBN / epoxy resin composite material, and the epoxy resin has a mass percentage content of 98.5% to 99.5% in the modified HBN / epoxy resin composite material.

[0020] In some embodiments of this application, the mass ratio of the polydopamine crosslinked HBN to the chitosan is (2.5-3.5):1.

[0021] In some embodiments of this application, the chitosan comprises coupling agent-modified chitosan.

[0022] Thirdly, this application provides a photovoltaic module, which includes a solar cell as described in the first aspect, or the photovoltaic module includes a solar cell prepared by the preparation method described in the second aspect.

[0023] Compared with the prior art, this application has at least the following beneficial effects:

[0024] This application provides a perovskite solar cell and a method for preparing a perovskite solar cell encapsulation material. The perovskite solar cell includes a cell body and a shell disposed on the outer surface of the cell body. The shell is sealed by an encapsulation layer, which includes an encapsulation material. The encapsulation material includes a modified HBN / epoxy resin composite material, wherein the modified HBN is composed of hexagonal boron nitride, polydopamine, and chitosan. The perovskite solar cell of this application, with its encapsulation layer containing a modified HBN / epoxy resin composite material, significantly improves the sealing performance of the perovskite solar cell compared to perovskite solar cells encapsulated with unmodified epoxy resin encapsulation material. This enhances the long-term operational stability of the perovskite solar cell and is beneficial for its industrial application. Furthermore, the perovskite solar cell exhibits low photoelectric conversion efficiency loss after encapsulation, ensuring the device efficiency of the perovskite solar cell. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a front cross-sectional view of a perovskite solar cell according to one embodiment of this application;

[0027] Figure 2 This is a top view of a perovskite solar cell according to one embodiment of this application;

[0028] Figure 3 This is a schematic diagram of the structure of a perovskite solar cell in another embodiment of this application;

[0029] Figure 4 This is a schematic diagram of the structure of the perovskite solar cell body in one embodiment of this application;

[0030] Figure 5 This is a schematic diagram of the synthesis process of the modified HBN / epoxy resin composite material of this application;

[0031] Figure 6 This is a comparison chart of the stability test results for Example 1 and Comparative Example 4;

[0032] Figure 7 The JV (current density-voltage) curves of the perovskite solar cell before and after encapsulation in Example 1 are shown.

[0033] Explanation of reference numerals in the attached drawings: Battery body - 1, Casing - 2, Encapsulation layer - 3, Electrode extension - 4, Substrate - 5, Hole transport layer - 6, Hole modification layer - 7, Perovskite layer - 8, Electron transport layer - 9, Buffer layer - 10, First transparent electrode layer - 11, Anti-reflection layer - 12, First seal - 21, Second seal - 22, Positive electrode - 41, Back electrode - 42, Bottom cell - 50, Second transparent electrode layer - 51, P-type doped crystalline silicon layer - 52, First intrinsic amorphous silicon layer - 53, N-type silicon wafer - 54, Second intrinsic amorphous silicon layer - 55, N-type doped crystalline silicon layer - 56, Composite layer - 57. Detailed Implementation

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0036] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0037] Furthermore, the terms "installation," "setup," "equipped with," "connection," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0038] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, elements, or components (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, elements, or components. Unless otherwise stated, "a plurality of" means two or more.

[0039] The technical solution of this application will be further described below with reference to the embodiments and accompanying drawings.

[0040] In related technologies, pure epoxy resin is used as an encapsulation material to encapsulate perovskite solar cells. However, during the curing process, solvent evaporation often creates micropores or microcracks within the epoxy resin. Water vapor and oxygen can easily penetrate these micropores or microcracks into the casing and reach the surface of the perovskite solar cell, causing corrosion. Furthermore, most epoxy resins contain a large number of hydrophilic functional groups or surface-active groups on their surface. The presence of these groups also accelerates the penetration of water and oxygen into the perovskite solar cell surface, affecting the long-term operational stability of the perovskite solar cell.

[0041] In view of this, in a first aspect, this application provides a perovskite solar cell, which includes a cell body and a housing disposed on the outer surface of the cell body. The housing is sealed by an encapsulation layer, which includes an encapsulation material. The encapsulation material includes a modified HBN / epoxy resin composite material, wherein the modified HBN is composed of hexagonal boron nitride, polydopamine (PDA), and chitosan.

[0042] For example, such as Figure 1 As shown, the casing 2 of the perovskite solar cell includes a first seal 21 and a second seal 22, wherein the cell body 1 is located between the first seal 21 and the second seal 22. The outer surface of the cell body 1 may or may not contact the first seal 21 and / or the second seal 22. (Reference) Figure 1 and Figure 2 The encapsulation layer 3 is disposed between the first seal 21 and the second seal 22, and the encapsulation layer 3 is disposed around the battery body 1, so that the casing 2 is sealed by the encapsulation layer 3.

[0043] The perovskite solar cell of this application includes a modified HBN / epoxy resin composite material in its encapsulation layer. Compared with perovskite solar cells encapsulated based on pure epoxy resin encapsulation material, this material can significantly improve the sealing performance of the perovskite solar cell, thereby improving the long-term operational stability of the perovskite solar cell and facilitating its industrial application. Furthermore, the perovskite solar cell exhibits low photoelectric conversion efficiency loss after encapsulation, ensuring the device efficiency of the perovskite solar cell.

[0044] The inventors discovered that when a modified HBN / epoxy resin composite material is applied to the encapsulation layer, the sealing performance of perovskite solar cells is significantly improved compared to perovskite solar cells encapsulated using pure epoxy resin encapsulation materials. This improvement, not limited to any particular theory, may be due to the following: in the modified HBN / epoxy resin composite material of this application, polydopamine can crosslink with HBN, thereby improving the dispersibility of HBN; chitosan can further crosslink with polydopamine to crosslink HBN; and HBN is prone to spontaneous aggregation. The layered structure of the modified HBN not only reduces the aggregation of HBN in the epoxy resin, thus reducing the impact of HBN aggregation on light transmittance, but also reduces micropores and microcracks in the epoxy resin. Through the interaction of these three materials in the modified HBN / epoxy resin composite material of this application, the impact of the encapsulation layer on light transmittance is reduced while suppressing micropores and microcracks in the epoxy resin. This results in perovskite solar cells exhibiting not only higher long-term operational stability but also lower photoelectric conversion efficiency loss after encapsulation, which is beneficial for the industrial application of perovskite solar cells.

[0045] Furthermore, compared to existing encapsulation materials such as ethylene-vinyl acetate copolymer, which suffer from problems like easy decomposition, yellowing, and poor water vapor barrier properties, the encapsulation material of this application exhibits excellent water and oxygen barrier properties, thermal stability, adhesion, and low vapor pressure. It can effectively block oxygen and moisture, improve the long-term operational stability of perovskite solar cells, and the synthesis steps of this encapsulation material are simple, low-cost, and the raw materials are widely available, which is conducive to subsequent large-scale production. Compared to existing UV-curable resins, which suffer from problems such as degassing vapor corrosion of the perovskite layer during encapsulation and damage to the perovskite layer in the vacuum high-pressure environment during vacuum hot-pressing encapsulation, the encapsulation material of this application can achieve rapid curing at room temperature. No encapsulation equipment is required during the encapsulation process, and no small molecule substances are released during the curing process. This effectively avoids the problem of traditional encapsulation processes adversely affecting the performance of perovskite solar cells, and has good adaptability to the encapsulation process of perovskite solar cells.

[0046] In one optional embodiment, the modified HBN content in the modified HBN / epoxy resin composite material is 0.5% to 1.5% by mass, and the epoxy resin content is 98.5% to 99.5% by mass. When the relative content of modified HBN is too low (e.g., below 0.5%), the inhibition effect on epoxy resin micropores and microcracks is weakened; when the relative content of modified HBN is too high (e.g., above 1.5%), it affects the light transmittance of the encapsulation layer. By controlling the content of modified HBN and epoxy resin in the modified HBN / epoxy resin composite material within the above-mentioned ranges, it is beneficial to improve the inhibition effect on epoxy resin micropores and microcracks while improving the dispersibility of modified HBN, thereby reducing the impact of the encapsulation layer on light transmittance while inhibiting epoxy resin micropores and microcracks.

[0047] In one optional embodiment, the thickness of the encapsulation layer is 100 μm to 400 μm. By adjusting the thickness of the encapsulation layer within this range, it is beneficial to improve the sealing performance of the encapsulation layer while reducing its impact on light transmittance.

[0048] In one optional embodiment, the weight-average molecular weight of chitosan is 20,000 to 50,000. By controlling the weight-average molecular weight of chitosan within the above range, chitosan is less prone to aggregation, which is beneficial to improving the dispersibility of chitosan in modified HBN, thereby enabling more complete cross-linking between chitosan and HBN.

[0049] In one alternative implementation, refer to Figure 3 The perovskite solar cell also includes an electrode extension 4, which is electrically connected to the electrodes of the cell body 1 and extends from the encapsulation layer 3 to the outside of the housing 2, thereby extracting the current generated by the perovskite solar cell. The electrodes of the perovskite solar cell of this application include a positive electrode and a back electrode, the materials of which include silver, and the materials of the electrode extension include copper. This application does not impose any particular limitations on the materials of the electrodes and the electrode extension.

[0050] In one optional implementation, the photoelectric conversion efficiency of the perovskite solar cell decreases by no more than 5% after 1000 hours of operation, demonstrating excellent long-term operational stability.

[0051] In one alternative embodiment, the perovskite solar cell includes a single-junction perovskite solar cell or a perovskite tandem solar cell.

[0052] In an optional embodiment, the encapsulating material further includes a curing agent. It is understood that the modified HBN / epoxy resin composite material of this application is cured by mixing it with a curing agent. This application does not impose any particular limitation on the mixing ratio of the modified HBN / epoxy resin composite material and the curing agent. For example, the modified HBN / epoxy resin composite material and the curing agent can be mixed at a mass ratio of 60–90:10–40, and those skilled in the art can flexibly adjust the above ratio according to the required curing time. This application does not impose any particular limitation on the curing agent, as long as it can achieve the curing of the modified HBN / epoxy resin composite material. For example, the curing agent includes, but is not limited to, at least one of polyamine curing agents, polyester curing agents, and thiol curing agents, preferably diethylenetriamine.

[0053] This application does not impose any particular restrictions on the material of the casing, as long as it achieves the purpose of this application. The casing material can be an inorganic or organic transparent material. For example, inorganic transparent materials include, but are not limited to, silicon dioxide, glass, etc.; organic transparent materials include, but are not limited to, methyl methacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET), transparent nylon, acrylonitrile-styrene copolymer (AS), etc.

[0054] The perovskite tandem solar cell of this application can be either a conventional perovskite tandem solar cell or an inverted perovskite tandem solar cell; this application does not have any particular limitation. When it is a perovskite tandem solar cell, refer to... Figure 4 The battery body 1 includes a substrate 5 and, sequentially disposed on the substrate 5, a hole transport layer 6, a hole modification layer 7, a perovskite layer 8, an electron transport layer 9, a buffer layer 10, a first transparent electrode layer 11, and an anti-reflection layer 12. The substrate 5 includes a bottom battery 50 and a composite layer 57 stacked on the bottom battery 50. The hole transport layer 6 is disposed on the composite layer 57, and the surface of the composite layer 57 facing the hole transport layer 6 may have a textured surface. The bottom battery 50, from bottom to top, includes a second transparent electrode layer 51, a P-type doped crystalline silicon layer 52, a first intrinsic amorphous silicon layer 53, an N-type silicon wafer 54, a second intrinsic amorphous silicon layer 55, and an N-type doped crystalline silicon layer 56. Furthermore, a positive electrode 41 is disposed on the light-receiving surface of the battery body 1, and a back electrode 42 is disposed on the back surface of the battery body 1.

[0055] The substrate of this application can be a solar cell based on a crystalline silicon substrate, and this application is not limited thereto. To better absorb solar energy, the composite layer of this application has a textured structure on the surface facing the hole transport layer (i.e., the light incident surface). For example, this textured structure can be a pyramid-shaped textured structure. This textured structure provides a higher surface area for the solar cell while reducing light reflection and diffusion. The surface of the hole transport layer and the textured structure of the composite layer have the same shape, both being pyramid-shaped, thus achieving the shape retention requirement of the textured structure. This application does not particularly limit the method of preparing the textured structure, as long as it achieves the purpose of this application.

[0056] The hole modification layer, hole transport layer, perovskite layer, and electron transport layer of this application can also be applied to single-junction perovskite solar cells. This application does not impose any particular restrictions on the structure of single-junction perovskite solar cells; any existing single-junction perovskite solar cell structure can be used.

[0057] Secondly, this application provides a method for preparing encapsulation materials for perovskite solar cells, comprising the following steps:

[0058] Step A: Add hexagonal boron nitride (HBN) to the polydopamine solution to carry out the first crosslinking reaction, and obtain polydopamine crosslinked HBN;

[0059] Step B: Add chitosan to the dispersion of polydopamine-crosslinked HBN to carry out the second crosslinking reaction and obtain modified HBN;

[0060] Step C: Mix the modified HBN with epoxy resin to obtain the modified HBN / epoxy resin composite material.

[0061] In step A, polydopamine and tris(hydroxymethyl)aminomethane hydrochloride (Tris-HCl) can be added to deionized water to dissolve the polydopamine, forming a polydopamine solution, and the pH of the polydopamine solution is adjusted to 8.5 ± 0.3. Then, HBN is added to the polydopamine solution and ultrasonically dispersed for 0.5 h to 1 h before use. The raw materials such as HBN and polydopamine used in this application can be obtained commercially. In addition, this application does not have a particular limitation on the particle size of HBN, as long as it can achieve the purpose of this application. For example, the average particle size of HBN is 300 nm to 500 nm.

[0062] In step B, the prepared polydopamine crosslinked HBN can be first dispersed in N,N-dimethylformamide (DMF) and ultrasonically treated to form a dispersion. Then, chitosan is added to the dispersion of polydopamine crosslinked HBN.

[0063] In step C, the modified HBN and epoxy resin can be mixed and then ultrasonically dispersed for 20 min to 40 min to ensure that the modified HBN and epoxy resin are fully mixed, thereby obtaining the modified HBN / epoxy resin composite material.

[0064] To give HBN a more pronounced lamellar structure, it can be pretreated before step A using the following method:

[0065] In an ice-water bath environment, 0.5 g to 2 g of HBN was placed in a three-necked flask. 20 mL to 30 mL of concentrated sulfuric acid was measured and mixed with HBN to obtain a mixture. Then, 0.05 g to 0.2 g of potassium permanganate was weighed and added to the mixture. After reacting for 10 to 15 hours, 8 mL to 12 mL of hydrogen peroxide was slowly added dropwise to a beaker to obtain a mixture. The mixture was then centrifuged for 20 to 40 minutes at a speed of 3000 to 5000 rpm. The supernatant was collected and microfiltered. The pH of the filtrate was then adjusted with sodium hydroxide solution (0.5 wt%) until the filtrate was neutral. The obtained product was placed in a vacuum oven and dried at 60°C to 80°C for 10 to 12 hours to obtain pretreated HBN.

[0066] The chitosan in this application is commercially available. The inventors have found that commercially available chitosan typically has a molecular weight of 500,000 to 1,000,000, which makes it prone to aggregation during the reaction process. Therefore, to reduce the molecular weight of chitosan, it can be pretreated using the following method:

[0067] 1.0 g–2.0 g of chitosan was dispersed in 40 mL–60 mL of acetic acid solution (acetic acid concentration 3 wt%–5 wt%). Then, 2 mL–4 mL of hydrogen peroxide solution (H2O2 concentration 5 wt%–7 wt%) was added dropwise under stirring at a constant temperature of 55 °C–65 °C. After reacting for 10 h–14 h, the pH of the reaction solution was adjusted to neutral with sodium hydroxide solution to induce precipitation. The product was then obtained by centrifugation and dried in a vacuum oven at 60 °C–80 °C for 10 h–12 h. The product was then ultrasonically dispersed in 80 mL of... A dispersion was formed in 120 mL of acetic acid solution (acetic acid concentration 0.5 wt% to 1.5 wt%), and the pH of the dispersion was adjusted to 4.8 ± 0.2. Then, 15 mL to 25 mL of sodium tripolyphosphate solution (sodium tripolyphosphate concentration 1 mg / mL to 3 mg / mL) was added dropwise to the above dispersion, and the mixture was stirred for 30 min to 40 min. The resulting product was ultrasonically dispersed in an ice-water bath for 15 min to 25 min, and then centrifuged and dried to obtain pretreated chitosan powder. The drying temperature was 60℃ to 80℃ and the drying time was 10 h to 12 h.

[0068] This application does not impose any particular restrictions on the reaction temperature and reaction time of the first crosslinking reaction, as long as it enables HBN to crosslink with polydopamine. For example, the first crosslinking reaction is carried out using water bath heating, with a reaction temperature of 55°C to 65°C and a reaction time of 20 to 30 hours.

[0069] This application does not impose any particular restrictions on the reaction temperature and reaction time of the second crosslinking reaction, as long as it enables the chitosan to crosslink with polydopamine and HBN. For example, the second crosslinking reaction is carried out using an oil bath for heating, with a reaction temperature of 100°C to 110°C and a reaction time of 10 to 15 hours.

[0070] In one optional embodiment, the modified HBN has a mass percentage content of 0.5% to 1.5% in the modified HBN / epoxy resin composite material, and the epoxy resin has a mass percentage content of 98.5% to 99.5% in the modified HBN / epoxy resin composite material. By controlling the content of modified HBN and epoxy resin within the above ranges, it is beneficial to improve the inhibitory effect of modified HBN on epoxy resin micropores and microcracks, and to improve the dispersibility of modified HBN, thereby reducing the influence of the encapsulation layer on light transmittance while inhibiting epoxy resin micropores and microcracks.

[0071] In one optional embodiment, the mass ratio of polydopamine-crosslinked HBN to chitosan is (2.5–3.5):1. By controlling the mass ratio of polydopamine-crosslinked HBN to chitosan within the above range, it is beneficial to ensure sufficient crosslinking between chitosan and polydopamine-crosslinked HBN, thereby improving the dispersibility of HBN.

[0072] In one alternative embodiment, the chitosan comprises coupling agent-modified chitosan.

[0073] To further improve the cross-linking ability of chitosan, this application can modify the pretreated chitosan powder using the following methods:

[0074] Chitosan powder is mixed with a coupling agent and stirred in a water bath at 75℃~85℃ for 10h~14h to obtain modified chitosan powder. This application does not impose any particular limitation on the type of silane coupling agent. For example, silane coupling agents include, but are not limited to, γ-aminopropyltriethoxysilane (KH550), glycidyl etheroxypropyltrimethoxysilane (KH560), aminosilane coupling agents (3-aminopropyltrimethoxysilane), silicate ester coupling agents (methyltri(methoxy)silane), silicate coupling agents (vinyltrimethoxysilane), fluorocarbon silane coupling agents (1H,1H,2H,2H-perfluorooctyltrimethoxysilane), etc.

[0075] For example, the specific process of chitosan modification includes:

[0076] 0.05 g to 0.2 g of chitosan powder and 1 g to 3 g of γ-aminopropyltriethoxysilane (KH550) were added to 40 mL to 60 mL of anhydrous ethanol and ultrasonically dispersed to obtain a mixture. The mixture was then stirred in a water bath at 75 °C to 85 °C for 10 h to 14 h. The product was centrifuged and dried to obtain modified chitosan powder.

[0077] This application does not impose any particular limitation on the type of epoxy resin, as long as it can achieve the purpose of this application. For example, epoxy resins include, but are not limited to, bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol E epoxy resin, bisphenol M epoxy resin, phenolic epoxy resin, etc.

[0078] Figure 5 This is a schematic diagram of the synthesis process of the modified HBN / epoxy resin composite material of this application. See [link / reference]. Figure 5 This application obtains polydopamine-crosslinked HBN by performing a first crosslinking reaction between HBN and polydopamine, and then performs a second crosslinking reaction between chitosan modified with a coupling agent and the polydopamine-crosslinked HBN to obtain modified HBN. In this modified HBN, HBN, polydopamine, and chitosan form a crosslinked structure, which is beneficial to improving the dispersibility of the modified HBN in epoxy resin, thereby making the modified HBN more uniformly distributed in epoxy resin and reducing the impact of perovskite encapsulation materials on light transmittance.

[0079] This application provides a method for preparing an encapsulation material for perovskite solar cells, resulting in a modified HBN / epoxy resin composite material. This modified HBN / epoxy resin composite material, when used as an encapsulation material for perovskite solar cells, not only enhances the long-term operational stability of the perovskite solar cells but also reduces photoelectric conversion efficiency loss after encapsulation, thus facilitating the industrial application of perovskite solar cells. Furthermore, the preparation method described in this application is simple, uses widely available and inexpensive raw materials, and is suitable for large-scale industrial production of perovskite solar cells.

[0080] Thirdly, this application provides a photovoltaic module comprising the perovskite solar cell as described in the first aspect.

[0081] This application also provides a photovoltaic module for converting received light energy into electrical energy and transmitting it to an external load. The photovoltaic module includes: at least one cell string, which is composed of multiple perovskite solar cells connected together; an encapsulating film for covering the surface of the cell string; and a cover plate for covering the surface of the encapsulating film facing away from the cell string.

[0082] Example

[0083] The following further describes the solar cell, its preparation method, and the photovoltaic module according to the embodiments of the present application in conjunction with more specific embodiments.

[0084] Example 1

[0085] <Pretreatment of HBN>

[0086] Under an ice-water bath environment, 1 g of HBN was placed in a three-necked flask, 25 mL of concentrated sulfuric acid (concentration 75 wt%) was measured and mixed with HBN and stirred to obtain a mixed solution, and then 1 g of potassium permanganate was weighed and added to the mixed solution. After reacting for 12 h, 10 mL of hydrogen peroxide was slowly dropped into the beaker to obtain a mixture, and then the obtained mixture was centrifuged for 30 min at a centrifugation speed of 4000 r / min. The supernatant was taken for microfiltration until the filtrate was neutral. The obtained product was placed in a vacuum oven for drying at a drying temperature of 60 °C and a drying time of 12 h to obtain pretreated HBN;

[0087] <Pretreatment of chitosan>

[0088] 1.5 g of chitosan was dispersed in 50 mL of acetic acid solution (acetic acid concentration 4 wt%), and then 3 mL of hydrogen peroxide solution (H2O2 concentration 6 wt%) was added dropwise under stirring conditions at a constant temperature of 60 °C. After reacting for 12 h, the pH of the reaction solution was adjusted to neutral with sodium hydroxide solution to precipitate the solution, and then the product was obtained by centrifugation and placed in a vacuum oven for drying at a drying temperature of 60 °C and a drying time of 12 h; then the product was ultrasonically dispersed in 100 mL of acetic acid solution (acetic acid concentration 1 wt%) to form a dispersion, and the pH value of the dispersion was adjusted to 4.8; then 20 mL of sodium tripolyphosphate solution (sodium tripolyphosphate concentration 2 mg / mL) was added dropwise to the above dispersion and stirred for 40 min. The obtained product was ultrasonically dispersed in an ice-water bath for 20 min, and then after centrifugation and drying, pretreated chitosan powder was obtained at a drying temperature of 60 °C and a drying time of 12 h.

[0089] <Preparation of polydopamine-crosslinked HBN>

[0090] 0.1 g of Tris-HCl and 0.2 g of polydopamine were added to 150 mL of deionized water, the pH was adjusted to 8.5, and then 0.4 g of pretreated HBN was added to the above solution and ultrasonically dispersed for 1 h. The obtained mixture was placed in a water bath at a temperature of 60 °C for the first crosslinking reaction for 24 h. Then the obtained product was centrifuged and dried for later use at a drying temperature of 60 °C and a drying time of 12 h;

[0091] <Modification of chitosan>

[0092] 0.1g of pretreated chitosan powder and 2g of silane coupling agent γ-aminopropyltriethoxysilane were added to 50mL of anhydrous ethanol and ultrasonically dispersed to obtain a mixture. The mixture was then reacted in an 80℃ water bath for 12h under stirring. The product was then centrifuged and dried for later use at 60℃ for 12h.

[0093] <Preparation of Modified HBN>

[0094] 0.15g of the prepared polydopamine crosslinked HBN was added to 50mL of DMF solution and sonicated to form a dispersion. Then, 0.05g of modified chitosan (i.e., the mass ratio of polydopamine crosslinked HBN to chitosan was 3:1) was added to the above dispersion and sonicated. The second crosslinking reaction was carried out in an oil bath at 105℃ under stirring conditions for 12h. The resulting product was then centrifuged and dried for later use at 60℃ for 12h.

[0095] <Preparation of Modified HBN / Epoxy Resin Composites>

[0096] The epoxy resin (bisphenol A type epoxy resin) and the prepared modified HBN were mixed at a mass ratio of 99:1 and ultrasonically dispersed for 30 min to obtain the modified HBN / epoxy resin composite material.

[0097] <Solar Cell Packaging>

[0098] The cover glass is used as a sealant to cover the perovskite solar cell to be encapsulated (size 2.47cm*2.47cm, effective area 1.07cm²). 2 The upper and lower surfaces of the perovskite solar cell are connected to the electrode to be tested by conductive copper strips. The modified HBN / epoxy resin composite material and the curing agent diethylenetriamine are mixed evenly at a mass ratio of 80:20 and coated around the perimeter of the perovskite solar cell. The mixture is left to stand at room temperature for 12 hours to obtain the encapsulated perovskite solar cell. The encapsulated perovskite solar cell is then placed in a vacuum oven and dried at 80°C for 5 hours in a dry environment (air humidity <10%RH). The encapsulation of the perovskite solar cell is completed after the epoxy resin is completely cured. The encapsulation layer thickness is 300μm.

[0099] Examples 2 to 7

[0100] Except for the section on "Preparation of Modified HBN / Epoxy Resin Composite Material", in which the amounts of modified HBN and epoxy resin were adjusted according to Table 1 to adjust their contents in the modified HBN / epoxy resin composite material, the rest of the instructions are the same as in Example 1.

[0101] Examples 8 to 11

[0102] Except for adjusting the addition ratio of polydopamine crosslinked HBN and modified chitosan according to Table 2 in the <Preparation of Modified HBN>, the rest is the same as in Example 1.

[0103] Comparative Example 1

[0104] Except for the encapsulation of perovskite solar cells using pure epoxy resin (bisphenol A type epoxy resin) in the section on "Solar Cell Encapsulation", the rest is the same as in Example 1.

[0105] Comparative Example 2

[0106] Except for not encapsulating the perovskite solar cells, everything else is the same as in Example 1.

[0107] Table 1: Preparation parameters of Examples 1-7 and Comparative Examples 1-2

[0108]

[0109]

[0110] Note: In Table 1, " / " indicates that the relevant preparation parameters do not exist.

[0111] Table 2: Preparation parameters of Examples 1, 8 to 11

[0112] Mass ratio of polydopamine crosslinked HBN to chitosan Example 1 3∶1 Example 8 2∶1 Example 9 2.5∶1 Example 10 3.5∶1 Example 11 4∶1

[0113] Performance testing:

[0114] Open-circuit voltage, short-circuit current density, fill factor, and initial photoelectric conversion efficiency tests:

[0115] The current (I)-voltage (V) of each packaged solar cell was measured using an IV tester (model: MX-MPVC-A20, manufacturer: Suzhou Maiwei Technology Co., Ltd.). The test light intensity was AM1.5G, the test temperature was 85℃, the humidity was RH≤10%, and the test time was 1000h. The open-circuit voltage, short-circuit current density, fill factor, and initial photoelectric conversion efficiency (efficiency value of the packaged device) (denoted as PCE0) and the photoelectric conversion efficiency after 1000h (denoted as PCE1) of the solar cell were obtained.

[0116] Performance testing of perovskite solar cells before and after packaging:

[0117] The performance of perovskite solar cells was tested using the Wavelabs solar simulator under the following conditions: AM1.5G, 1000W / m. 2The test environment temperature was 25℃. Before testing, the light source was calibrated to simulate sunlight intensity using a standard silicon cell. Performance tests included power conversion efficiency (PCE0), open-circuit voltage, short-circuit current density, and fill factor. The packaged device was placed in an air environment (temperature 25℃, humidity RH 50%) for 1000 hours and then tested again; the corresponding photoelectric conversion efficiency was measured as PCE1.

[0118] Table 3: Performance data of each embodiment and comparative example

[0119]

[0120] Combining Tables 1 and 3, it can be seen from Examples 1 to 7 and Comparative Example 1 that although the PCE0 of Comparative Example 1 is close to that of Example 1, the PCE1 is lower. This may be because Comparative Example 1 uses pure epoxy resin for encapsulation, which makes it difficult to suppress the micropores and microcracks in the epoxy resin. During the long-term operation of the solar cell, water vapor and oxygen can more easily enter the encapsulated device, leading to more severe and faster degradation of the perovskite solar cell. Figure 6 It can be seen that the photoelectric conversion efficiency of the perovskite solar cell in Comparative Example 2 was less than 10% after 1000 hours of testing, and it had basically completely degraded; while the perovskite solar cell of this application still maintained a high photoelectric conversion efficiency after 1000 hours of testing. In particular, the perovskite solar cell of Example 1 still maintained more than 95% of its initial photoelectric conversion efficiency after 1000 hours of testing, indicating that the encapsulation material of this application is conducive to achieving long-term operational stability of the perovskite solar cell.

[0121] Combining Tables 2 and 3, it can be seen from Examples 1, 8 to 11 that, based on the encapsulation material of this application in the encapsulation layer of the perovskite solar cell, by adjusting the mass ratio of polydopamine crosslinked HBN to chitosan within the range of this application, it is beneficial to obtain a perovskite solar cell with long-term operational stability.

[0122] Table 4: Performance data of perovskite solar cells before and after packaging in Example 1

[0123]

[0124] Combine Table 4 and Figure 7 As can be seen, the perovskite solar cell of Example 1 did not show significant degradation after encapsulation, indicating that the encapsulation material of this application will hardly cause performance damage to the perovskite solar cell, which is beneficial to achieving non-destructive encapsulation of perovskite solar cells.

[0125] The foregoing has provided a detailed description of a perovskite solar cell and a method for preparing encapsulation materials for perovskite solar cells disclosed in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the technical solutions and core inventive points of the embodiments of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A perovskite solar cell, characterized in that, It includes a battery body and a housing disposed on the outer surface of the battery body, the housing being sealed by an encapsulation layer, the encapsulation layer including an encapsulation material; The encapsulation material includes a modified HBN / epoxy resin composite material, wherein the modified HBN is composed of hexagonal boron nitride, polydopamine, and chitosan.

2. The perovskite solar cell according to claim 1, characterized in that, The modified HBN has a mass percentage content of 0.5% to 1.5% in the modified HBN / epoxy resin composite material, and the epoxy resin has a mass percentage content of 98.5% to 99.5% in the modified HBN / epoxy resin composite material.

3. The perovskite solar cell according to claim 1, characterized in that, The thickness of the encapsulation layer is 100μm to 400μm.

4. The perovskite solar cell according to claim 1, characterized in that, The weight-average molecular weight of the chitosan is 20,000 to 50,000.

5. The perovskite solar cell according to claim 1, characterized in that, The perovskite solar cell further includes an electrode extension that is electrically connected to the electrode of the cell body and extends from the encapsulation layer to the outside of the housing.

6. The perovskite solar cell according to claim 1, characterized in that, The photoelectric conversion efficiency of the perovskite solar cell decreases by no more than 5% after 1000 hours of operation.

7. The perovskite solar cell according to any one of claims 1 to 6, characterized in that, The perovskite solar cells include single-junction perovskite solar cells or perovskite tandem solar cells.

8. A method for preparing an encapsulation material for perovskite solar cells, characterized in that, Includes the following steps: Hexagonal boron nitride was added to a polydopamine solution to carry out the first crosslinking reaction, resulting in polydopamine crosslinked HBN. Chitosan was added to the dispersion of the polydopamine-crosslinked HBN to carry out a second crosslinking reaction, thereby obtaining modified HBN; The modified HBN is mixed with epoxy resin to obtain a modified HBN / epoxy resin composite material.

9. The preparation method according to claim 8, characterized in that, The reaction temperature of the first crosslinking reaction is 55℃~65℃, and the reaction time is 20h~30h.

10. The preparation method according to claim 8, characterized in that, The reaction temperature of the second crosslinking reaction is 100℃~110℃, and the reaction time is 10h~15h.

11. The preparation method according to claim 8, characterized in that, The modified HBN has a mass percentage content of 0.5% to 1.5% in the modified HBN / epoxy resin composite material, and the epoxy resin has a mass percentage content of 98.5% to 99.5% in the modified HBN / epoxy resin composite material.

12. The preparation method according to claim 8, characterized in that, The mass ratio of the polydopamine crosslinked HBN to the chitosan is (2.5-3.5):

1.

13. The preparation method according to claim 8, characterized in that, The chitosan includes coupling agent-modified chitosan.

14. A photovoltaic module, characterized in that, The photovoltaic module includes the perovskite solar cell according to any one of claims 1 to 7.

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