Space anti-radiation solar cell module and its packaging method

Abstract

The application discloses a kind of space anti-radiation solar cell module and its packaging method.The solar cell module, from light-receiving surface to back surface, includes in sequence: front plate protective layer, first encapsulation adhesive film layer, solar cell piece, second encapsulation adhesive film layer and back plate protective layer;Wherein, the first encapsulation adhesive film layer and second encapsulation adhesive film layer are thermosetting polyolefin elastomer (POE) adhesive film;The front plate protective layer is colorless transparent polyimide (CPI) film;In preparation, under high temperature and pressure at 140~160 ℃, the deep chemical crosslinking reaction occurs in POE adhesive film, and POE forms the three-dimensional network structure of space extreme heat environment resistance.The application fundamentally solves the problem of module attenuation and load under space extreme environment.

Description

Technical Field

[0001] This invention belongs to the field of aerospace photovoltaic materials and devices, specifically relating to a lightweight solar cell module encapsulation structure and its fabrication method suitable for high-irradiation, high-low temperature alternating, and vacuum environments. It is particularly applicable to the encapsulation and protection of flexible and lightweight photovoltaic devices such as space-use perovskite solar cells and gallium arsenide solar cells. Background Technology

[0002] With the rapid development of aerospace technology, satellite communications, and near-space vehicles, space-based solar cells, as a core energy supply system for spacecraft, face extremely high requirements for "high specific power (W / kg)" and "long-term environmental tolerance." Perovskite solar cells, due to their high photoelectric conversion efficiency, large theoretical specific power, and flexibility potential, have become a research hotspot in next-generation space photovoltaic technology. However, the extremely harsh space environment, with its dramatic temperature fluctuations (e.g., -100℃ to +120℃), high vacuum, and intense ultraviolet and high-energy particle radiation, poses significant challenges to the encapsulation of solar cell modules.

[0003] In existing technologies, space solar cells are mostly encapsulated using a structure of "radiation-resistant glass + silicone rubber + solar cell". This structure has several obvious shortcomings: 1. Organic silica gel has a high water vapor transmission rate (WVTR) and poor water and oxygen barrier properties, making it unable to provide long-term protection for new types of batteries that are extremely sensitive to water and oxygen (such as perovskite batteries). 2. In the high vacuum environment of space, silicone rubber has the problem of small molecule volatiles escaping (gas release), which can easily condense and contaminate the light-facing surfaces of spacecraft optical lenses or components; 3. Traditional radiation-resistant glass is heavy and rigid, which increases the launch payload and cannot meet the deformation requirements for some new spacecraft such as solar panels that pursue extreme lightweighting or require flexible folding functions.

[0004] To address the issue of poor water resistance of silicone, existing technologies employ encapsulation methods using polyolefin elastomers (POE) (such as the perovskite battery encapsulated with ordinary POE disclosed in publication number CN105489772A), which are primarily designed for conventional ground environments. However, as patent (publication number CN109671789A) points out, existing ordinary thermoplastic POEs, due to the thermoplasticity (easily softens and melts when heated) of polyolefin elastomers, suffer from fatal drawbacks such as poor heat resistance, easy melting and deformation, and severe radiation attenuation under alternating high and low temperatures and high radiation environments.

[0005] In summary, there is an urgent need for a space-use solar cell module encapsulation technology that can simultaneously achieve water and oxygen barrier properties, extremely low volatility, resistance to high and low temperatures, radiation resistance, and lightweight flexibility. Summary of the Invention

[0006] This invention addresses the problems of poor water and oxygen barrier properties, high vacuum venting rates, poor high-temperature resistance of thermoplastic films, and excessive weight of glass cover plates in existing space solar cell encapsulation materials. It provides a space-grade radiation-resistant solar cell module and its encapsulation method. This invention uses thermosetting POE with a cross-linking degree (gel content) ≥75% to replace traditional silicone or ordinary thermoplastic POE, and uses CPI film to replace the heavy radiation-resistant glass. Under high temperature and pressure of 140~160℃, a deep chemical cross-linking reaction occurs inside the POE film, resulting in a three-dimensional network structure of POE resistant to the extreme heat environment of space. This invention fundamentally solves the problems of module degradation and load under extreme space environments.

[0007] The technical solution of this invention is as follows: A space-use radiation-resistant solar cell module, comprising, from the light-facing side to the back-facing side: a front panel protective layer, a first encapsulating film layer, solar cells, a second encapsulating film layer, and a back panel protective layer; Wherein, both the first encapsulating film layer and the second encapsulating film layer are thermosetting polyolefin elastomer (POE) films; The front panel protective layer is a colorless and transparent polyimide (CPI) film; The light-receiving surface of the front panel protective layer (i.e., the outer surface facing away from the solar cell and towards the space environment) is further provided with one or more of an antigenic oxygen coating, an anti-ultraviolet coating, or an anti-radiation coating.

[0008] The solar cell is a perovskite solar cell, a perovskite-crystalline silicon tandem cell, or a gallium arsenide thin-film solar cell.

[0009] The backsheet protective layer is a substrate material suitable for space environments, such as polyimide (PI) film, carbon fiber composite board, or radiation-resistant glass.

[0010] The thermosetting POE film contains silane coupling agent, crosslinking agent and radiation-resistant additive; its degree of crosslinking (gel content) after component encapsulation and curing is ≥75% to ensure the formation of a three-dimensional network structure.

[0011] The front panel protective layer is preferably a colorless and transparent polyimide (CPI) film with a thickness of 10~50μm.

[0012] The thickness of the first and second encapsulating film layers may be the same or different, each ranging from 100 to 400 μm; their water vapor transmission rate (WVTR) is ≤1.0 g / (m²). 2(day) (38℃, 90%RH conditions); the peel strength between the cured thermosetting POE film and the front panel protective layer is ≥40 N / cm, and the light transmittance of the first encapsulation film layer is ≥90%.

[0013] The encapsulation method for the space-use radiation-resistant solar cell module includes the following steps: Step 1, Material Preparation: Cut the front sheet protective layer, thermosetting POE film, and back sheet protective layer to the size that matches the solar cell. Step 2, Lamination Assembly: In a cleanroom environment, the backsheet protective layer, the second layer of thermosetting POE film, the solar cell, the first layer of thermosetting POE film, and the front sheet protective layer are placed sequentially from bottom to top to form the module to be laminated. Step 3, Vacuum Lamination and Cross-linking Curing: The components to be laminated are placed in the laminator, and heating, pressurization, and vacuuming are performed in stages. The specific process is as follows: (1) Vacuuming stage: Vacuum at 90~110℃ for 5~10min to remove air between layers and low molecular weight volatiles in the film; (2) Hot-press crosslinking stage: Heat to 140~160℃, apply pressure of 0.05~0.1MPa, and maintain for 15~30min to allow the thermosetting POE film to melt, flow, and undergo a deep crosslinking reaction; (3) Cooling and cooling stage: Cool to room temperature while maintaining pressure, release vacuum and pressure, and obtain space solar cell module.

[0014] The essential features of this invention are: This invention aims to solve the core problems of photovoltaic module degradation and excessively heavy space launch payload and low specific power in the high-irradiance and high-low temperature alternating environment of space. It provides a specific vertical material replacement and stacking structure of "CPI film (front panel) - thermoset POE (encapsulation) - cell".

[0015] 1. Synergistic effect of thermodynamic stability and barrier properties: This invention uses thermosetting (crosslinked) POE to replace traditional silicone and ordinary thermoplastic POE. After lamination, thermosetting POE forms a dense three-dimensional crosslinked network structure, which not only perfectly overcomes the technical bias of ordinary thermoplastic POE being prone to melting and softening in the extreme heat environment of space, but also has a water and oxygen barrier capacity that far exceeds that of silicone, providing a near-sealed physical barrier for water and oxygen sensitive perovskite batteries in complex microenvironments.

[0016] 2. Synergistic effect of extremely low volatility and radiation resistance: The optimized thermosetting POE system has extremely low total mass loss (TML) and collected condensable volatile matter (CVCM), which fundamentally solves the problem of "gas leakage" pollution of silicone in a vacuum environment; at the same time, its saturated carbon chain structure, combined with the front plate protective layer, greatly improves the ability to resist degradation by high-energy particles and ultraviolet rays from the universe.

[0017] 3. Synergistic Effect of Interfacial Stress Matching and Lightweighting: While replacing glass with CPI film alone can reduce weight, CPI has a fatal flaw in the space environment: its extreme flexibility. If ordinary silicone is used for bonding, the difference in thermal expansion coefficients will generate huge interlayer shear forces, making the CPI film prone to peeling failure due to thermal expansion stress under the drastic high and low temperature fluctuations of -100℃ to 120℃ in space. This invention combines the CPI film with an underlying thermoset POE, producing a significant interfacial synergistic effect: the elastic three-dimensional network structure formed by the cross-linking of thermoset POE not only gives the component flexibility and extremely low weight, but also provides a peel strength of ≥40 N / cm, perfectly buffering the severe interfacial interlayer stress caused by thermal expansion and contraction between the CPI film and the solar cell. This specific combination prevents CPI film delamination and avoids microcracks in the solar cell, achieving a synergistic enhancement of "ultimate weight reduction" and "fatigue-resistant peeling".

[0018] Compared with the prior art, the present invention has the following significant advantages: 1. Significantly improved adaptability to space environments: The use of thermosetting POE solves the defects of traditional thermoplastic POE, such as poor heat resistance and easy flow. The module does not delaminate or soften during high and low temperature alternating tests from -100℃ to +150℃, and has an extremely low vacuum gas leakage rate, making it perfectly suitable for the harsh space environment; 2. Excellent protection of the core active layer: The extremely low water vapor permeability of thermosetting POE effectively blocks the external environment from corroding the internal cells (especially the perovskite layer). Compared with the closest existing technology using traditional silicone encapsulation (such as Comparative Example 1, whose efficiency retention rate after 1000 hours of dual 85 aging is only 38%), the preferred module of this invention (Example 1) achieves an efficiency retention rate of up to 92% under the same extreme test conditions, with a 54% reduction in efficiency degradation rate, significantly extending battery life. 3. Specific lightweight and flexibility: In the preferred CPI / PI front panel scheme of this invention, the specific power (W / kg) of the component achieves an order-of-magnitude leap, and endows the component with the physical characteristics of being rollable and foldable, which greatly reduces the launch cost of the spacecraft. By significantly reducing the dead weight of the energy system (compared to traditional radiation-resistant glass components, the dead weight of the component itself is reduced by more than 75%), the payload space of the spacecraft is effectively released, the overall loading capacity of the spacecraft is improved, and the best solution is provided for the development of flexible solar panels. 4. Good interface compatibility and no light absorption loss: CPI and thermosetting POE have excellent adhesion and light transmittance matching, and no interfacial microbubbles are generated, ensuring high photoelectric conversion efficiency. Attached Figure Description

[0019] Figure 1 This is a schematic cross-sectional view of the stacked structure of the space-use radiation-resistant solar cell module of the present invention. Detailed Implementation

[0020] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the following embodiments. This embodiment uses a perovskite solar cell as the core active layer for illustration.

[0021] The POE film involved in this invention is a known material. The film used in the following examples was purchased from Hangzhou Foster Applied Materials Co., Ltd., and its model is XUR150. However, it is not limited thereto.

[0022] Example 1: A lightweight solar cell module for space use has the following structure from top to bottom: a CPI front protective layer (25μm) with an anti-UV coating (specifically a 30nm thick SiO2 transparent coating) pre-coated on the surface - a first thermosetting POE film (200μm) - a flexible perovskite cell - a second thermosetting POE film (200μm) - a polyimide (PI) (50μm) backsheet.

[0023] Preparation method: 1. Stacked assembly: Place the PI backsheet, lower POE, perovskite solar cell, upper POE, and CPI film in sequence.

[0024] 2. Vacuum Lamination: Place the film in a laminator and apply a vacuum at 100°C (absolute pressure maintained below 50 Pa) for 8 minutes to remove air between layers and low-molecular-weight volatiles from the film. Then, pressurize to 0.08 MPa and heat to 150°C for 20 minutes to allow the thermosetting POE film to melt, level, and undergo a deep cross-linking reaction. Maintain pressure and cool to room temperature to obtain the final product. The cross-linking degree of the film, measured using the standard xylene extraction method, is 82%, far exceeding the 75% threshold. As a polymer material, it has formed an insoluble and infusible dense cross-linked three-dimensional network structure within the film.

[0025] The flexible perovskite solar cell in Example 1 adopts an inverted series structure, and its core photoelectric active layer material is formamide cesium lead iodide bromide (FAB). 0.85 Cs 0.15 Pb(I 0.85 Br 0.15)3) The overall size of the light-receiving surface of the component is 30cm*40cm, and it is composed of multiple sub-cells that are laser-etched and connected in series.

[0026] Example 2: A space-use radiation-resistant solar cell module has the following structure from top to bottom: radiation-resistant glass (100μm) - first layer of thermosetting POE film (300μm) - perovskite cell - second layer of thermosetting POE film (300μm) - glass backsheet.

[0027] The lamination crosslinking parameters were adjusted to: 100℃ vacuum for 10 min, followed by 145℃ pressure curing for 25 min. The crosslinking degree was measured to be 78%.

[0028] Example 3: A high-power-density solar cell module for space use has the following structure: a PI film (30 μm) pre-coated with an atomic oxygen-resistant coating - a first thermosetting POE film (150 μm) - a flexible multi-junction gallium arsenide cell - a second thermosetting POE film (150 μm) - a PI backsheet. The preparation method is the same as in Example 1.

[0029] Example 4: A space-use radiation-resistant solar cell module, with the same structure as Example 2, differs in that the thicknesses of both the first and second encapsulating film layers are adjusted to 400 μm, and the lamination curing parameters are adjusted to 160°C for 15 min. The crosslinking degree of the encapsulating film was measured to be 90%, further improving the thermal stability of the module at extremely high temperatures.

[0030] Comparative Example 1 (Traditional Spaceflight Solution): The structure is as follows: radiation-resistant glass - silicone layer - perovskite solar cell - silicone layer - glass backsheet. The thickness of the two silicone layers is the same as in Example 1 (200 μm) to ensure the consistency of the comparison variable. Encapsulation is completed using room temperature dispensing and heat curing processes.

[0031] Comparative Example 2 (Ordinary thermoplastic POE solution): The structure is the same as in Example 1, but the encapsulating film is a common thermoplastic POE film without added crosslinking agent. The lamination process is hot pressing at 110°C (no crosslinking reaction).

[0032] Performance testing methods and instrument standards: The data for the embodiments and comparative examples of this invention were obtained based on the following standards and instruments: (1) Thermal vacuum evaporation test: Performed in accordance with aerospace standard ASTM E595, using a thermal vacuum evaporation test system to measure total mass loss (TML) and collected condensable volatiles (CVCM).

[0033] (2) High and low temperature thermal shock and double 85 aging test: The test was conducted in accordance with the international standard for photovoltaic modules IEC 61215 and using a high and low temperature alternating damp heat test chamber.

[0034] (3) Photovoltaic conversion efficiency (PCE): Using a standard AM1.5G solar simulator (total irradiance 100 mW / cm²) 2 Combined with a high-precision digital source meter, the performance degradation of each component before and after aging was tested and compared under standard test conditions.

[0035] Table 1: Comparison of spatial environment adaptability and photoelectric performance tests of each embodiment and comparative example

[0036] Note: The general acceptable thresholds for aerospace-grade low-emission materials are TML ≤ 1.0% and CVCM ≤ 0.1%. "-" indicates that the comparison item has failed prematurely under the corresponding extreme environment or cannot be accurately measured due to deformation.

[0037] As can be seen from Table 1, the present invention can not only save novel and extremely fragile perovskite batteries (Example 1), but also perfectly adapt to traditional, high-value space gallium arsenide batteries (Example 3), and has great industrial application value.

[0038] Data Analysis and Conclusions: 1. Thermal vacuum and gas exhaust test (simulating space environment): Examples 1 and 4 are in 10 -5 Tested under high vacuum (Pa) and 125°C for 24 hours. Results showed that Example 1 had a total mass loss (TML) of 0.06% and volatile organic compound (CVCM) of 0.008%. Example 4, due to its higher crosslinking degree (90%), further reduced its thermal weight loss to 0.04%, both far below the aerospace-grade threshold requirements (typically requiring TML ≤ 1.0% and CVCM ≤ 0.1%). This demonstrates that increasing the crosslinking degree of thermosetting POE significantly enhances its structural stability under extreme vacuum and high temperature. In contrast, Comparative Example 1 (silicone silicone) had a TML as high as 1.5% and a CVCM of 0.25%, exhibiting significant oligomer evaporation and condensation; while Comparative Example 2 showed film softening and adhesive overflow at high temperatures.

[0039] 2. High and low temperature cycling test (thermal shock test): The cells underwent 200 cycles of thermal shock testing between -100°C and +120°C. No delamination or cell breakage was observed in Examples 1, 2, and 3. Furthermore, the relative degradation of the photoelectric conversion efficiency (PCE) after cycling was measured to be 3.5%, 4.2%, and 1.8%, respectively, all strictly controlled within 5%. Example 3 demonstrates that the encapsulation structure of this invention also provides excellent mechanical stress buffering for gallium arsenide thin-film batteries, reflecting the broad applicability of this solution to different types of space thin-film batteries.

[0040] 3. Long-term water resistance and component performance retention rate: After 1000 hours of double 85 aging test, the PCE retention rate of the perovskite module in Example 1 reached as high as 92%. In contrast, the PCE retention rate of Comparative Example 1 (silicone silicone) dropped significantly to 38% due to its high water vapor permeability; the PCE retention rate of Comparative Example 2 (ordinary thermoplastic POE) was only 65%. This proves that the thermosetting POE combination of the present invention effectively blocks water vapor erosion and ensures the long-term output of the module.

[0041] 4. Specific power evaluation: Examples 1 and 3 employ thin films instead of glass, resulting in extremely low module areal density. Testing showed that the specific power of the module in Comparative Example 1 (traditional radiation-resistant glass solution) was approximately 180 W / kg; while the specific power of Example 1 (CPI / perovskite solution) reached 860 W / kg as shown in Table 1, and the specific power of the flexible gallium arsenide module in Example 3 was as high as 1120 W / kg, representing a 4 to 6-fold improvement over the traditional structure. This fully validates the core value of the "CPI / PI + thermoset POE" solution in achieving extreme lightweighting of space batteries.

[0042] in conclusion: The data from the examples fully demonstrate that the combination of "CPI (or radiation-resistant glass) + thermosetting POE" adopted in this invention not only completely solves the problems of gas escaping and poor water resistance of traditional silicone, but also overcomes the technical bias that ordinary thermoplastic POE is not resistant to high temperatures in space, achieving a perfect unity of high stability, radiation resistance and extreme lightweight of space solar cells.

[0043] Expansion of implementation methods In this invention, the solar cell is not limited to perovskite single-junction cells, but is also applicable to silicon-based cells, multi-junction gallium arsenide (GaAs) flexible thin-film cells, and other devices sensitive to water, oxygen, or stress. The surface of the front protective layer can also be further coated with an anti-reflection film or an antigenic oxygen (AO) coating to adapt to the more complex space microenvironment such as low Earth orbit (LEO), and has broad prospects for commercial aerospace applications.

[0044] Matters not covered in this invention are common knowledge.

Claims

1. A space-use radiation-resistant solar cell module, characterized in that, From the light-facing side to the back-facing side, it includes, in sequence: front panel protective layer, first encapsulation film layer, solar cell, second encapsulation film layer and back panel protective layer; Wherein, both the first encapsulating film layer and the second encapsulating film layer are thermosetting polyolefin elastomer (POE) films; The front panel protective layer is a colorless and transparent polyimide film with a thickness of 10~50μm.

2. The space-use radiation-resistant solar cell module as described in claim 1, characterized in that, The thickness of the first encapsulating film layer and the second encapsulating film layer may be the same or different, and each is independently 100~400μm; Its water vapor transmission rate (WVTR) is ≤1.0 g / (m²). 2 (day) (38℃, 90%RH conditions); the peel strength between the cured thermosetting POE film and the front panel protective layer is ≥40 N / cm, and the light transmittance of the first encapsulation film layer is ≥90%.

3. The space-use radiation-resistant solar cell module as described in claim 1, characterized in that, The degree of crosslinking of the thermosetting POE film is ≥75%.

4. The space-use radiation-resistant solar cell module as described in claim 1, characterized in that, The solar cell is a perovskite solar cell, a perovskite-crystalline silicon tandem cell, or a gallium arsenide thin-film solar cell; The backsheet protective layer is a polyimide (PI) film, a carbon fiber composite board, or radiation-resistant glass.

5. The space-use radiation-resistant solar cell module as described in claim 1, characterized in that, The light-receiving surface of the front panel protective layer is further provided with one or more of the following: an anti-ionic oxygen coating, an anti-ultraviolet coating, or an anti-radiation coating.

6. The encapsulation method for a space-use radiation-resistant solar cell module as described in claim 1, characterized in that, Includes the following steps: Step 1, Material Preparation: Cut the front sheet protective layer, thermosetting POE film, and back sheet protective layer to the size that matches the solar cell. Step 2, Lamination Assembly: In a cleanroom environment, the backsheet protective layer, the second layer of thermosetting POE film, the solar cell, the first layer of thermosetting POE film, and the front sheet protective layer are placed sequentially from bottom to top to form the module to be laminated. Step 3, Vacuum Lamination and Cross-linking Curing: The components to be laminated are placed in the laminator, and heating, pressurization, and vacuuming are performed in stages; the specific process is as follows: (1) Vacuuming stage: Vacuum at 90~110℃ for 5~10min; (2) Hot-press crosslinking stage: Heat to 140~160℃, apply pressure of 0.05~0.1MPa, and maintain for 15~30min; (3) Cooling and cooling stage: Cool to room temperature while maintaining pressure, release vacuum and pressure, and obtain space solar cell module.

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