A high flatness space solar cell preparation method and solar cell

Abstract

The application relates to a high-flatness space solar cell preparation method and a solar cell, and the preparation method comprises the following steps: preparing electrodes on the front surface and the back surface of a solar cell epitaxial wafer respectively; evaporating an anti-reflection film on the front surface of the solar cell wafer; alloying the solar cell wafer; low-temperature processing the solar cell wafer, wherein the low-temperature processing comprises placing the solar cell wafer in preset low temperature for a certain time, and then restoring the solar cell wafer to room temperature; and pasting an anti-radiation glass cover on the solar cell wafer. The application improves the flatness of the solar cell, can fully paste the solar cell assembly to a solar wing substrate, avoids the risk of the solar cell fragmenting and falling during assembly pasting caused by the adhesive stress sealing due to the warping degree of the solar cell, guarantees the safety of the solar cell on the solar wing, avoids the solar cell fragmenting and the on-orbit current reduction caused by the warping of the solar cell, and effectively improves the reliability of the satellite solar wing.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, specifically to a method for preparing a high-flatness space solar cell and the solar cell itself. Background Technology

[0002] In recent years, my country's aerospace technology has developed rapidly, and the demand for satellite launches has been increasing. As the sole power supply unit for satellites, solar panels have also received increasing attention. Satellite solar panels typically consist of hundreds to tens of thousands of space solar cells. These solar cells utilize the photovoltaic effect to convert solar energy into electrical energy in the space environment to power the satellite's on-orbit operation. Therefore, the flatness, power generation efficiency, and on-orbit environmental adaptability of the solar cells play a crucial role in the normal operation of the solar panels.

[0003] Satellite solar panels operating in orbit typically face extremely harsh space environments. Satellites in LEO orbit experience nearly 22 daily temperature fluctuations ranging from -100°C to over +100°C. This places stringent requirements on the resistance of solar cell circuitry materials to these extreme temperatures. Frequent temperature fluctuations can easily cause thermal stress buildup in the solar cells, leading to breakage and abnormal power generation, potentially resulting in a drop in overall satellite current and other malfunctions. Therefore, the impact of the harsh space environment must be considered during ground-based design to ensure the solar cells can withstand it. During the development of space solar cells on the ground, flatness measurements revealed that some ground-developed space solar cells exhibited significant warpage (exceeding 0.2 mm). High warpage can lead to excessive adhesive stress during the mounting process of space solar cell modules. Furthermore, the forward warpage of the cells results in uneven adhesive distribution at the bottom of the cells during module mounting, leaving more adhesive residue in the center compared to the perimeter. In the high vacuum and high temperature environment of space, adhesive degassing can cause significant stress on the cells, potentially leading to breakage if the stress exceeds the cell's yield strength. Simultaneously, warped cells can easily introduce external air bubbles or form gas cavities during module mounting. These defects, once in a vacuum, can create a significant pressure difference, further stressing the cells and severely impacting the on-orbit reliability of satellite solar arrays.

[0004] However, solar cells manufactured using current methods generally suffer from excessive warpage, which can easily lead to excessive bonding stress and trapped air bubbles during solar panel development. This can easily cause solar cell fragmentation and other malfunctions during environmental testing and even orbital operation. Therefore, there is a need to find a method for manufacturing space-use solar cells with high flatness. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing high-flatness space solar cells and a solar cell, thereby solving the problem that solar cells prepared by existing methods generally have excessive warpage.

[0006] To achieve the above objectives, the present invention provides a method for fabricating a high-flatness space solar cell, comprising: fabricating electrodes on the front and back sides of a solar cell epitaxial wafer; depositing an anti-reflection film on the front side of a single solar cell; alloying the single solar cell; and performing low-temperature treatment on the single solar cell, wherein the low-temperature treatment includes placing the single solar cell in a preset low temperature environment for a certain period of time, and then restoring the single solar cell to room temperature; and attaching a radiation-resistant glass cover to the single solar cell.

[0007] In the above-mentioned method for preparing high-flatness space solar cells, the solar cell is subjected to low-temperature treatment by sequentially placing the solar cell into two low-temperature chambers at different temperatures and maintaining them in the two low-temperature chambers for a certain period of time; then the solar cell is restored to room temperature.

[0008] The above-mentioned method for preparing high-flatness spatial solar cells includes a specific method for low-temperature treatment of individual solar cells: first, the alloyed solar cell is placed in a first low-temperature chamber and kept there for 1 to 100 minutes, with the temperature range of the first low-temperature chamber being -80°C to -180°C; then, the solar cell is removed from the first low-temperature chamber and placed in a second low-temperature chamber, with the temperature range of the second low-temperature chamber being -10°C to -80°C, and kept there for 1 to 100 minutes; finally, the solar cell is removed from the second low-temperature chamber and placed in a clean room-temperature environment to stand until room temperature.

[0009] The above-mentioned method for preparing high-flatness spatial solar cells includes a first low-temperature chamber with a temperature range of -90℃ to -130℃, which is maintained for 1 min to 15 min; a solar cell is removed from the first low-temperature chamber and placed into a second low-temperature chamber for a time controlled within 2 min; the second low-temperature chamber has a temperature range of -20℃ to -50℃, which is maintained for 1 min to 30 min.

[0010] The above-mentioned method for preparing high-flatness space solar cells includes the following steps: applying an adhesive layer to the solar cell and then attaching the radiation-resistant glass cover to the adhesive layer; the radiation-resistant glass cover is a high-strength radiation-resistant glass cover or a flexible radiation-resistant glass cover, and the surface of the radiation-resistant glass cover is coated with an anti-reflection layer.

[0011] In the above-mentioned method for preparing high-flatness space solar cells, the adhesive is a single-component room-temperature vulcanizing silicone rubber with a thickness of 150 μm; the radiation-resistant glass cover is made of quartz glass with a thickness of 120 μm; and the anti-reflective layer is preferably a magnesium fluoride layer.

[0012] The above-mentioned method for preparing high-flatness space solar cells, wherein the solar cell monolayer alloy is specifically prepared by: maintaining the solar cell monolayer at a certain heating temperature for a preset time, wherein the preset time is 30 min to 700 min, and the heating temperature is between 200℃ and 500℃.

[0013] In the above-mentioned method for preparing high-flatness spatial solar cells, the anti-reflection film deposited on the front side of a single solar cell is a Ti3O5 / Al2O3 double-layer anti-reflection film, wherein the thickness of the Ti3O5 is 20nm to 90nm and the thickness of the Al2O3 is 10nm to 100nm.

[0014] The above-mentioned method for fabricating high-flatness spatial solar cells includes the following steps: fabricating electrodes on the front and back sides of the solar cell epitaxial wafer, respectively: fabricating a positive electrode on the front side of the solar cell epitaxial wafer; etching the back side of the solar cell epitaxial wafer; and fabricating a back electrode of the solar cell epitaxial wafer; wherein the solar cell is a gallium arsenide solar cell.

[0015] Another technical solution provided by the present invention is a high-flatness space solar cell, which is prepared by the above-mentioned high-flatness space solar cell preparation method.

[0016] Compared with the prior art, the beneficial technical effects of the present invention are:

[0017] The high-flatness space solar cell manufacturing method of the present invention greatly improves the flatness of space solar cells while ensuring that the solar cells meet the requirements for use in space. It can effectively increase the matching degree between the solar cell module and the solar cell array substrate, and can fully and completely attach the solar cell module to the solar cell array substrate, avoiding the risk of fragmentation and explosion, reducing the cell fragmentation rate, effectively improving the reliability of space solar cells, and improving the work efficiency of the process implementation at the satellite solar cell production and assembly site. Attached Figure Description

[0018] The method for preparing high-flatness space solar cells and the solar cells of the present invention are given by the following embodiments and figures.

[0019] Figure 1 This is a flowchart of the method for preparing high-flatness space solar cells according to the present invention.

[0020] Figure 2This is a flowchart of the low-temperature processing of a single solar cell in this invention. Detailed Implementation

[0021] The following will combine Figures 1-2 The method for preparing high-flatness space solar cells and the solar cells of the present invention will be described in further detail.

[0022] Figure 1 The diagram shows a flowchart of the method for preparing high-flatness space solar cells according to the present invention.

[0023] See Figure 1 The method for fabricating high-flatness space solar cells of the present invention includes:

[0024] 1) Prepare a positive electrode (N-end) on the front side of the solar cell epitaxial wafer;

[0025] 1-1) The positive electrode pattern is prepared on the front side of the solar cell epitaxial wafer using photolithography;

[0026] 1-2) Preparation of the positive electrode;

[0027] 1-3) Positive electrode stripping;

[0028] 2) Etching of the back side (P-end) of the solar cell epitaxial wafer;

[0029] 3) Fabrication of the back electrode of a solar cell epitaxial wafer;

[0030] A conductive metal electrode layer is deposited on the back side of a solar cell epitaxial wafer using a vacuum evaporation method. The metal of the electrode layer is a composite metal electrode layer composed of one or more of gold, silver, gold-germanium-nickel, and palladium, preferably a composite metal electrode layer composed of palladium, silver, and gold.

[0031] After electrodes are fabricated on the front and back sides of the solar cell epitaxial wafer, a single solar cell is obtained.

[0032] 4) An anti-reflective coating is deposited on the front side of a single solar cell;

[0033] 4-1) Photolithography is used to fabricate the overlay pattern of the front electrode on the front side of a single solar cell.

[0034] 4-2) Selective corrosion;

[0035] 4-3) Preparation of antireflective coating;

[0036] An antireflection film is prepared by vacuum evaporation. The antireflection film is preferably a Ti3O5 / Al2O3 double-layer antireflection film. The thickness of the Ti3O5 is 20nm to 90nm, more preferably 25nm to 50nm, and the thickness of the Al2O3 is 10nm to 100nm, more preferably 30nm to 80nm.

[0037] Based on the structure of a single space solar cell, a double-layer anti-reflection film system of a specific thickness was designed, and the best anti-reflection effect was obtained through experimental verification. By depositing a Ti3O5 / Al2O3 double-layer anti-reflection film of a specific thickness on the front side of a single space solar cell, the operating current of the single space solar cell can be increased by 40% to 50%.

[0038] 4-4) Remove adhesive from antireflective coating;

[0039] 5) Solar cell monolayer alloy;

[0040] The solar cell is kept at a certain heating temperature for a preset time, wherein the preset time is 30 min to 700 min, more preferably 360 min to 600 min, and the heating temperature is between 200℃ and 500℃, more preferably 300℃ to 450℃.

[0041] 6) Low-temperature treatment of individual solar cells;

[0042] The solar cell is placed in a pre-set low-temperature chamber for a certain period of time, and then the solar cell is restored to room temperature. The main principle of this step is to release excess thermal stress by plastic deformation of the metal through low temperature.

[0043] This invention involves sequentially placing solar cells into two low-temperature chambers (defined as a first low-temperature chamber and a second low-temperature chamber) and maintaining them in each chamber for a specific time. Specifically, the solar cell is first placed in the first low-temperature chamber and maintained at a specific temperature (defined as the first temperature) for a certain time. Then, the solar cell is removed from the first low-temperature chamber and placed in the second low-temperature chamber (this process is controlled to last no more than 2 minutes) and maintained at a specific temperature (defined as the second temperature) for a certain time. Afterward, the solar cell is removed from the second low-temperature chamber and placed in a clean, room-temperature environment to allow it to cool to room temperature. Figure 2 The temperature range of the first low-temperature chamber (i.e., the first temperature) is -80℃ to -180℃, preferably -90℃ to -130℃, and the chamber is left to stand in the first low-temperature chamber for 1 min to 100 min, preferably 1 min to 15 min; the temperature range of the second low-temperature chamber (i.e., the second temperature) is -10℃ to -80℃, preferably -20℃ to -50℃, and the chamber is left to stand in the second low-temperature chamber for 1 min to 100 min, preferably 1 min to 30 min.

[0044] 7) Radiation-resistant glass cover sheets are attached to individual solar cells;

[0045] An adhesive is applied to the top of a solar cell, and then a radiation-resistant glass cover is attached to the adhesive. The adhesive is silicone rubber, preferably a one-component room temperature vulcanizing silicone rubber with a thickness of 150 μm. The radiation-resistant glass cover is a high-strength radiation-resistant glass cover or a flexible radiation-resistant glass cover, preferably made of quartz glass with a thickness of 120 μm. An anti-reflective layer is deposited on the surface of the radiation-resistant glass cover, preferably a magnesium fluoride layer.

[0046] By attaching high-strength radiation-resistant glass covers to individual solar cells, the cell's resistance to space particle radiation is increased, while its mechanical properties are greatly enhanced, reducing the risk of cell breakage due to external forces. Simultaneously depositing a magnesium fluoride antireflective film on the glass cover surface increases the transmittance of incident light, reducing surface reflection loss from 3% to 2% and improving the operating current of the space solar cell.

[0047] This invention provides a method for manufacturing high-flatness space-grade solar cells to address issues such as adhesive stress sealing and solar cell fragmentation caused by excessive solar cell warpage during the mounting process on satellite solar array modules. By improving the process, this invention reduces the warpage of the solar cells, maintaining the photoelectric conversion efficiency and yield strength of the space-grade solar cells while enhancing their flatness. This allows for more efficient mounting of the solar cell module onto the satellite solar array substrate, significantly reducing cell fragmentation, ensuring the safety of the solar cells on the solar array, preventing cell fragmentation and on-orbit current reduction caused by cell warpage, and effectively improving the reliability of the satellite solar array.

[0048] Example 1

[0049] The method for fabricating high-flatness space solar cells in this embodiment specifically includes the following steps:

[0050] 1) A positive electrode (N-end) is fabricated on the front side of a gallium arsenide solar cell epitaxial wafer;

[0051] First, a positive electrode grid pattern is prepared on the front side of a gallium arsenide solar cell epitaxial wafer using photolithography. Specifically, photoresist is first applied to the front side of the epitaxial wafer, and after the photoresist dries, it is exposed. After exposure, development is performed. The positive electrode is prepared using vacuum evaporation, and then the unwanted positive electrode in the photoreaction region is removed by positive electrode stripping.

[0052] 2) Etching of the back side (P-end) of gallium arsenide solar cell epitaxial wafers;

[0053] First, a protective adhesive is applied to the front positive electrode (N end) of the gallium arsenide solar cell epitaxial wafer. After the protective adhesive dries, the back side (P end) of the gallium arsenide solar cell epitaxial wafer is etched. The protective adhesive and application method, as well as the etching method for the back side (P end), can be implemented according to industry standard practices.

[0054] 3) Fabrication of the back electrode of a gallium arsenide solar cell epitaxial wafer;

[0055] A conductive metal electrode layer is deposited on the back side of a gallium arsenide solar cell epitaxial wafer using a vacuum evaporation method. The deposition method can be implemented according to industry standard methods.

[0056] 4) An anti-reflective coating is deposited on the front side of a single gallium arsenide solar cell.

[0057] First, the front electrode overlay pattern is prepared on the front side of the gallium arsenide solar cell using photolithography. Then, selective etching is used to selectively etch the cap layer of the gallium arsenide solar cell. The photoresist and etching method used can be implemented using industry-standard methods. The antireflection film material is deposited onto the front side of the solar cell using vacuum evaporation. The antireflection film is a Ti3O5 / Al2O3 double-layer antireflection film, in which the thickness of Ti3O5 is 40nm and the thickness of Al2O3 is 60nm.

[0058] 5) Alloying gallium arsenide solar cells into single-cell alloys;

[0059] The gallium arsenide solar cell is kept at a certain heating temperature for a preset time of 500 min, and the preset heating temperature is between 350℃ and 400℃.

[0060] 6) Low-temperature treatment of gallium arsenide solar cells;

[0061] A single gallium arsenide (GaAs) solar cell is placed in a first low-temperature chamber and kept at a certain temperature for a period of time. The temperature of the first low-temperature chamber is set to -100℃ and the holding time is set to 7 minutes. The single GaAs solar cell is then removed from the first low-temperature chamber (the operation time is controlled to not exceed 2 minutes) and placed in a second low-temperature chamber and kept at a certain temperature for a period of time. The temperature of the second low-temperature chamber is set to -30℃ and the holding time is set to 8 minutes. After that, the single GaAs solar cell is removed from the second low-temperature chamber and placed in a clean room temperature environment to stand until it reaches room temperature.

[0062] 7) Radiation-resistant glass covers are attached to individual gallium arsenide solar cells;

[0063] A layer of single-component room temperature vulcanizing silicone rubber is coated on top of a gallium arsenide solar cell, and then an anti-radiation quartz glass cover plate coated with a magnesium fluoride anti-reflection layer is attached to the top of the single-component room temperature vulcanizing silicone rubber.

[0064] The gallium arsenide solar cell in this embodiment can be a single-junction gallium arsenide solar cell or a multi-junction gallium arsenide solar cell, preferably a triple-junction gallium arsenide solar cell.

Claims

1. A method for fabricating high-flatness space solar cells, characterized in that, include: Electrodes were fabricated on the front and back sides of the solar cell epitaxial wafer, respectively. An anti-reflective coating is deposited on the front side of a single solar cell. Solar cell monolayer alloy; The low-temperature treatment of a single solar cell includes placing the single solar cell in a preset low temperature environment for a certain period of time, and then restoring the single solar cell to room temperature. Radiation-resistant glass cover is attached to each individual solar cell. The specific process for low-temperature treatment of the solar cell is as follows: First, the alloyed solar cell is placed in a first low-temperature chamber and kept there for 1 to 100 minutes. The temperature range of the first low-temperature chamber is -80°C to -180°C. Then, the solar cell is removed from the first low-temperature chamber and placed in a second low-temperature chamber. The temperature range of the second low-temperature chamber is -10°C to -80°C. The solar cell is kept there for 1 to 100 minutes. After that, the solar cell is removed from the second low-temperature chamber and placed in a clean room temperature environment to stand until it reaches room temperature. Specifically, the solar cell single-cell alloy is used to maintain a certain heating temperature for a preset time, wherein the preset time is 30 min to 700 min and the heating temperature is between 200℃ and 500℃.

2. The method for fabricating high-flatness space solar cells as described in claim 1, characterized in that, The temperature range of the first low-temperature chamber is -90℃ to -130℃, and the temperature is maintained in the first low-temperature chamber for 1 min to 15 min. The solar cell is removed from the first low-temperature chamber and placed in the second low-temperature chamber for a time controlled within 2 min. The temperature range of the second low-temperature chamber is -20℃ to -50℃, and the temperature is maintained in the second low-temperature chamber for 1 min to 30 min.

3. The method for fabricating high-flatness space solar cells as described in claim 1, characterized in that, The solar cell single-cell radiation-resistant glass cover includes: An adhesive is applied to the top of a solar cell, and then an anti-radiation glass cover is attached to the adhesive. The anti-radiation glass cover is a high-strength anti-radiation glass cover or a flexible anti-radiation glass cover, and an anti-reflective layer is vapor-deposited on the surface of the anti-radiation glass cover.

4. The method for fabricating high-flatness space solar cells as described in claim 3, characterized in that, The adhesive is a one-component room temperature vulcanizing silicone rubber with a thickness of 150 μm; the radiation-resistant glass cover is made of quartz glass with a thickness of 120 μm; and the antireflective layer is a magnesium fluoride layer.

5. The method for fabricating high-flatness space solar cells as described in claim 1, characterized in that, In the aforementioned antireflective coating deposited on the front side of a single solar cell, the antireflective coating is a Ti3O5 / Al2O3 double-layer antireflective coating, wherein the thickness of the Ti3O5 is 20nm to 90nm and the thickness of the Al2O3 is 10nm to 100nm.

6. The method for fabricating high-flatness space solar cells as described in claim 1, characterized in that, The preparation of electrodes on the front and back sides of the solar cell epitaxial wafer includes: A positive electrode is fabricated on the front side of a solar cell epitaxial wafer; Corrosion on the back of the solar cell epitaxial wafer; Fabrication of back electrode for solar cell epitaxial wafers; The solar cell is a gallium arsenide solar cell.

7. A high-flatness space solar cell, characterized in that, It is prepared by the high flatness spatial solar cell preparation method as described in any one of claims 1 to 6.

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