A protection method for thin-film gallium arsenide solar cells in a hot and humid salt fog environment

Abstract

The present invention discloses a method for protecting thin-film gallium arsenide solar cells in a hot and humid salt fog environment. The present invention first performs chip-level primary protection on thin-film battery monomers, and then performs secondary protection at the battery component level according to conventional interconnection welding and lamination packaging. The specific steps include surface cleaning of thin-film gallium arsenide solar cells, hydroxylation pretreatment of the back electrode surface, activation and hydrolysis of organic silicon molecules, film formation on the battery substrate surface, battery circuit welding, and conventional lamination packaging. The present invention can solve the problem of device failure of thin-film gallium arsenide solar cells due to electrochemical corrosion in hot and humid salt fog environments, improve the reliability of high-efficiency thin-film components in coastal environment applications, and is particularly suitable for protecting solar cells in high-temperature, high-humidity, and high-salt fog environments on the ocean and sea surface.

Description

Technical Field

[0001] The invention belongs to the field of solar cell protection, and in particular relates to a method for protecting thin-film solar cells in a hot, humid and salt-fog environment. Background Art

[0002] Most long-flight solar drones use highly efficient and lightweight thin-film solar cells as their main source of energy supply. For drones used in coastal frontier defense and marine fields, the storage and flight of the entire drone involve high temperature, high humidity and high salt fog environments. In such environments, the solar cell circuits will corrode significantly, the performance will be greatly attenuated, and the power generation of the energy system will be greatly reduced, which will seriously affect the life of the entire drone.

[0003] At present, thin-film GaAs solar cell modules are encapsulated with weather-resistant and highly transparent films. This encapsulation structure can prevent mechanical damage to thin-film cells and has good adaptability in high and low temperature, ultraviolet and other environments. However, this type of encapsulation does not meet the protection requirements for the effects of humidity, heat and salt spray in terms of materials and structure. Water vapor and salt spray can diffuse into the thin-film cell through the upper and lower films and the sides of the encapsulation components, and electrochemical corrosion occurs at the high-purity back electrode, generating micro-current channels between metals with different potentials (metal and impurities) on the side wall, causing a significant degradation of the electrical performance of the solar cell.

[0004] On the other hand, the thin-film solar cell modules for drones have high requirements for light transmittance, flexibility and surface density of protective materials due to their special shape and application. The three-proof treatment of conventional equipment cannot meet the protection requirements of thin-film batteries. Summary of the invention

[0005] The purpose of the present invention is to overcome the above defects and provide a method for protecting thin-film gallium arsenide solar cells in a hot and humid salt fog environment. The present invention first performs chip-level primary protection on thin-film battery monomers, and then performs secondary protection at the battery component level according to conventional interconnection welding and lamination packaging. The specific steps include cleaning the surface of thin-film gallium arsenide solar cells, hydroxylation pretreatment of the back electrode surface, activation and hydrolysis of organic silicon molecules, film formation on the surface of the battery substrate, battery circuit welding, and conventional lamination packaging. The present invention can solve the problem of device failure caused by electrochemical corrosion of thin-film gallium arsenide solar cells in hot and humid salt fog environments, improve the reliability of high-efficiency thin-film components in coastal environment applications, and is particularly suitable for protecting solar cells in high-temperature, high-humidity, and high-salt fog environments on the ocean and sea surface.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] A method for protecting a thin-film gallium arsenide solar cell in a hot and humid salt fog environment comprises the following steps:

[0008] (1) Cleaning and air-drying the surface of the thin-film gallium arsenide solar cell monomer;

[0009] (2) using alkaline solution to perform hydroxylation on the back electrode of a thin-film gallium arsenide solar cell monomer;

[0010] (3) Mixing an organic silicon reagent, anhydrous ethanol and water, adjusting the pH of the mixed solution to be acidic, and stirring to obtain an organic silicon molecule hydrolysis solution; the organic silicon reagent contains a structural formula of YR-SiX 3 A compound wherein X is a hydrolyzable functional group bonded to a silicon atom, Y is an organic functional group, and R is a carbon chain having a saturated bond or an unsaturated bond;

[0011] (4) placing the thin-film gallium arsenide solar cell monomer in a hydrolysis solution of organic silicon molecules and then taking it out to dry;

[0012] (5) Connect the electrodes of each thin-film gallium arsenide solar cell monomer according to the requirements of series and parallel connection, and package them.

[0013] Furthermore, in step (1), the surface of the thin-film gallium arsenide solar cell monomer is cleaned by ultrasonic cleaning with anhydrous ethanol and deionized water for 5 to 10 minutes in sequence, and then placed on filter paper for air drying.

[0014] Furthermore, in step (2), the concentration of -OH radicals in the alkali solution is 0.2 to 5 mol / L.

[0015] Furthermore, the specific method of using alkaline solution to perform hydroxylation treatment on the back electrode of the thin-film gallium arsenide solar cell in step (2) is:

[0016] (21) applying an alkaline solution to the back electrode of a thin-film gallium arsenide solar cell monomer;

[0017] (22) keeping the thin film gallium arsenide solar cell at 50 to 150° C. for 10 to 60 minutes;

[0018] (23) Ultrasonic cleaning of the surface of the thin-film GaAs solar cell was performed with deionized water for 5–10 min and the surface was air-dried on filter paper.

[0019] Furthermore, in step (3), X is one of chloro, methylamino or ethoxy, and Y is amino or epoxy.

[0020] Furthermore, in step (3), the volume ratio of the organosilicon reagent, anhydrous ethanol and water is 5:1:1 to 1:1:1.

[0021] Furthermore, in step (3), acetic acid is used to adjust the pH of the entire mixed solution to 4-6, and the organic silicon molecule hydrolysis solution is obtained after stirring for 10-20 minutes.

[0022] Furthermore, in step (4), when the thin-film gallium arsenide solar cell monomer is allowed to stand in the organic silicon molecule hydrolysis solution, the thin-film gallium arsenide solar cell monomer is completely immersed in the organic silicon molecule hydrolysis solution; in the step (4), the thin-film gallium arsenide solar cell monomer is allowed to stand in the organic silicon molecule hydrolysis solution for 2 to 5 minutes, and after being taken out, it is placed in a 50° C. constant heat drying oven for 15 to 60 minutes.

[0023] Furthermore, in step (5), resistance welding, soldering or conductive silver glue is used to connect the electrodes of each thin-film gallium arsenide solar cell monomer;

[0024] In step (5), a negative pressure high temperature process with a temperature of 80° C. to 150° C. and a pressure of 50 KPa to 80 KPa is used to laminate the interconnected thin film gallium arsenide solar cell monomers and the packaging material to achieve packaging.

[0025] Furthermore, the lower thin-film gallium arsenide solar cell is GaInP 2 / GaAs / InGaAs triple junction thin film gallium arsenide solar cell, the back electrode of the thin film gallium arsenide solar cell monomer is copper or Pt with a thickness of 10 to 50 μm.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] (1) The protection method of the present invention performs primary chip-level protection on thin-film battery cells, and then performs secondary protection on battery module level according to conventional interconnection welding and lamination packaging, which can ensure the reliability of solar cell performance during the equipment life cycle at a relatively low weight cost;

[0028] (2) When the protection method of the present invention performs chip-level primary protection on a thin-film battery cell, the back electrode is first subjected to hydroxylation treatment, and then a film is formed on the surface of the thin-film gallium arsenide solar cell. The hydroxylation treatment can improve the adhesion between the silicon-based thin film and the back electrode. The surface film is attached to the electrode surface in the form of a chemical bond through dehydration condensation with the hydroxyl groups on the back electrode surface, which has a stronger adsorption force than ordinary molecular bonds;

[0029] (3) The present invention specifically designs the ratio of the alkali solution used for hydroxylation treatment of the back electrode and the organic silicon molecule hydrolysis solution used for film formation on the surface of the thin-film gallium arsenide solar cell, so that it can form an efficient and stable protection without damaging the structure of the cell itself;

[0030] (4) The present invention is simple to operate and has low cost, and is particularly suitable for protecting thin-film gallium arsenide solar cells in a hot and humid salt fog environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The present invention is a flow chart of a method for protecting thin-film gallium arsenide solar cells in a hot and humid salt fog environment. DETAILED DESCRIPTION

[0032] The following detailed description of the present invention will make the features and advantages of the present invention more clear and explicit.

[0033] The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise noted.

[0034] like Figure 1 The present invention provides a protection method for thin-film gallium arsenide solar cells. First, a chip-level primary protection method is used for thin-film battery monomers, and then a secondary protection method at the battery component level is performed according to conventional interconnection welding and lamination packaging, including the following steps and process conditions:

[0035] (1) Cleaning the surface of thin-film cells: Ultrasonic clean the thin-film GaAs solar cell monomer with anhydrous ethanol and deionized water for 5 to 10 minutes, and place it on filter paper to air dry;

[0036] (2) Hydroxylation treatment of the back electrode surface: a low-concentration alkali solution with an -OH radical concentration of 0.2 to 5 mol / L is applied to the high-purity metal electrode on the back of the thin-film gallium arsenide solar cell, and then placed in a high-temperature drying oven at 50 to 150°C for 10 to 60 minutes for alkali heat treatment, and then the surface is ultrasonically cleaned with deionized water for 5 to 10 minutes and placed on filter paper for air drying;

[0037] (3) Preparation of organic silicon molecule activated hydrolysis solution: organic silicon reagent, anhydrous ethanol and water are mixed in a volume ratio of 5:1:1 to 1:1:1, and the pH value is adjusted to between 4 and 6 with acetic acid, and stirred for 10 to 20 minutes to make it uniform, and the organic silicon molecules are fully activated and hydrolyzed to obtain an organic silicon molecule hydrolysis solution; the organic silicon reagent contains a structural formula of YR-SiX 3 A compound wherein X is a hydrolyzable functional group bonded to a silicon atom, including but not limited to chloro, methylamino, ethoxy, etc., Y is an organic functional group, including but not limited to amino, epoxy, etc.; R is a carbon chain having a saturated or unsaturated bond;

[0038] (4) Film formation on the battery substrate surface: Place the thin-film gallium arsenide battery cell in the battery slot, introduce the organic silicon molecule hydrolysis solution into the battery slot, ensure that the battery cell is completely immersed in the hydrolysis solution, let it stand for 2 to 5 minutes, take out the battery cell, and place it in a 50°C constant temperature drying oven for 15-60 minutes;

[0039] In this step, after the organic silicon molecules are hydrolyzed, they undergo a dehydration reaction with the surface of the thin-film gallium arsenide battery to form covalent bond adsorption, and further undergo a condensation reaction to form organic silicon oligomers on the surface of the thin-film gallium arsenide battery to cover the film. Thus, the thin-film battery chip-level primary protection is completed;

[0040] (5) Battery circuit welding: According to the requirements of series and parallel connection, the positive and negative electrodes of the battery cells are reliably interconnected by means of resistance welding, soldering or conductive silver glue;

[0041] (6) Battery lamination packaging: The batteries that meet the series-parallel requirements are laminated with upper and lower packaging materials using a negative pressure and high temperature process at a temperature of 80°C to 150°C and a pressure of 50KPa to 80KPa. This completes the secondary protection of the thin-film battery module level.

[0042] The thin-film gallium arsenide solar cell of the present invention includes but is not limited to GaInP 2 / GaAs / InGaAs triple-junction thin-film gallium arsenide solar cell, the back electrode is a metal substrate of the thin-film battery, and its material includes but is not limited to copper, Pt, etc., with a thickness of 15-50μm.

[0043] Example 1

[0044] (1) 20 μm thick copper substrate (back electrode) GaInP 2 The / GaAs / InGaAs triple-junction thin-film gallium arsenide solar cell was placed in a battery tray and ultrasonically cleaned with anhydrous ethanol and deionized water for 5 minutes, then taken out and placed on filter paper for air drying.

[0045] (2) A 0.2 mol / L NaOH solution was applied to the copper electrode on the back of the thin-film gallium arsenide solar cell and placed in a 50°C drying oven for alkaline heat treatment for 45 min. After being taken out, the surface was ultrasonically cleaned with deionized water for 5 min and placed on filter paper for air drying.

[0046] (3) Add vinyl alkoxysilane to a mixed solution of water and ethanol, add acetic acid to control the pH value of the solution to 4, and stir evenly.

[0047] (4) Place the treated thin-film battery cell in the battery slot, introduce the hydrolysis solution into the battery slot, ensure that the battery cell is completely immersed in the hydrolysis solution, let it stand for 2 minutes, take out the battery cell, and place it in a 50°C constant temperature drying oven for 30 minutes.

[0048] (5) The cells are connected in series and in parallel using silver interconnecting ribbons by resistance welding, and the thin-film solar cell module is packaged using fluoroplastic film, PO type adhesive film and PI film at a lamination temperature of 150° C. and a pressure of 70 kPa. The thin-film solar cell module obtained in this example is numbered 1.

[0049] Example 2

[0050] (1) Using 30μm thick copper substrate GaInP 2 The / GaAs / InGaAs triple-junction thin-film gallium arsenide solar cell was placed in a battery tray and ultrasonically cleaned with anhydrous ethanol and deionized water for 5 minutes, then taken out and placed on filter paper for air drying.

[0051] (2) A 1 mol / L NaOH solution was applied to the copper electrode on the back of the thin-film GaAs solar cell and placed in a 50°C drying oven for alkaline heat treatment for 20 min. After being taken out, the surface was ultrasonically cleaned with deionized water for 10 min and placed on filter paper for air drying.

[0052] (3) Dissolve the chloroalkyl alkoxysilane in ethanol, add it into deionized water, add acetic acid to control the pH value of the solution to 3, and stir evenly.

[0053] (4) Place the treated thin-film battery cell in the battery slot, introduce the hydrolysis solution into the battery slot, ensure that the battery cell is completely immersed in the hydrolysis solution, let it stand for 3 minutes, take out the battery cell, and place it in a 50°C constant temperature drying oven for 30 minutes.

[0054] (5) Conductive silver glue is used to complete the shingled interconnection of solar cell strings, and modified PET packaging film and EVA adhesive film are used to complete the packaging of thin-film solar cell modules at a lamination temperature of 130° C. and a pressure of 70 kPa. The thin-film solar cell module obtained in this example is numbered 2.

[0055] The thin-film solar cell modules 1 and 2 prepared by the above protection method were aged for 200 h in a hot and humid environment box at a temperature of 85°C and a humidity of 85%, and subjected to a salt spray test in accordance with the relevant provisions of GB / T2423.17. After the samples were taken out, IV electrical performance tests were performed, and the test data were shown in Table 1. The photoelectric conversion efficiency decay was within 5%.

[0056] Table 1 Electrical performance test results of solar cells before and after wet heat and salt spray tests after protection by the present invention

[0057]

[0058] Comparative Example 1:

[0059] The remaining steps are the same as those in Example 1, but the battery is not subjected to secondary protection by the method of the present invention, and only a conventional lamination process is used to achieve component-level protection for the battery cells. The obtained solar cell component is numbered 3.

[0060] Comparative Example 2:

[0061] The remaining steps are the same as those in Example 2, but the battery is not subjected to secondary protection by the method of the present invention. Only conventional lamination process is adopted to achieve component-level protection for the battery cells. The obtained solar cell component is numbered 4.

[0062] The solar cell modules 3 and 4 were aged for 200 h in a hot and humid environment box at a temperature of 85°C and a humidity of 85%. Salt spray tests were performed in accordance with the relevant provisions of GB / T2423.17. After the samples were taken out, IV electrical performance tests were performed. The test data are shown in Table 2. The photoelectric conversion efficiency decayed by more than 20%.

[0063] Table 2 Electrical performance test results of conventional package components before and after damp heat and salt spray tests

[0064]

[0065] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

[0066] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A method for protecting thin-film gallium arsenide solar cells in a hot and humid salt fog environment, characterized in that: The steps include: (1) Cleaning and air-drying the surface of the thin-film gallium arsenide solar cell monomer; (2) using alkaline solution to perform hydroxylation on the back electrode of a thin-film gallium arsenide solar cell monomer; (3) mixing an organosilicon reagent, anhydrous ethanol and water, adjusting the pH of the mixed solution to acidic, and stirring to obtain an organosilicon molecule hydrolysis solution; the organosilicon reagent comprises a compound with a structural formula of YR-SiX3, wherein X is a hydrolyzable functional group bonded to a silicon atom, Y is an organic functional group, and R is a carbon chain with a saturated bond or an unsaturated bond; (4) placing the thin-film gallium arsenide solar cell monomer in a hydrolysis solution of organic silicon molecules and then taking it out to dry; (5) Connect the electrodes of each thin-film gallium arsenide solar cell monomer according to the requirements of series and parallel connection, and package them.

2. The method for protecting thin-film gallium arsenide solar cells in a hot and humid salt fog environment according to claim 1, characterized in that: In step (1), the surface of the thin-film gallium arsenide solar cell monomer is cleaned by ultrasonic cleaning with anhydrous ethanol and deionized water for 5 to 10 minutes in sequence, and then placed on filter paper for air drying.

3. The method for protecting thin-film gallium arsenide solar cells in a hot and humid salt fog environment according to claim 1, characterized in that: In step (2), the concentration of -OH radical in the alkali solution is 0.2 to 5 mol / L.

4. The method for protecting thin-film gallium arsenide solar cells in a hot and humid salt fog environment according to claim 1 or 3, characterized in that: The specific method of step (2) using alkaline solution to perform hydroxylation treatment on the back electrode of the thin-film gallium arsenide solar cell is: (21) applying an alkaline solution to the back electrode of a thin-film gallium arsenide solar cell monomer; (22) keeping the thin film gallium arsenide solar cell at 50 to 150° C. for 10 to 60 minutes; (23) Ultrasonic cleaning of the surface of the thin-film GaAs solar cell was performed with deionized water for 5–10 min and the surface was air-dried on filter paper.

5. The method for protecting thin-film gallium arsenide solar cells in a hot and humid salt fog environment according to claim 1, characterized in that: In step (3), X is one of chloro, methylamino or ethoxy, and Y is amino or epoxy.

6. The method for protecting thin-film gallium arsenide solar cells in a hot and humid salt fog environment according to claim 1, characterized in that: In step (3), the volume ratio of the organosilicon reagent, anhydrous ethanol and water is 5:1:1 to 1:1:

1.

7. The method for protecting thin-film gallium arsenide solar cells in a hot and humid salt fog environment according to claim 1, characterized in that: In step (3), acetic acid is used to adjust the pH of the entire mixed solution to 4-6, and the organic silicon molecule hydrolysis solution is obtained after stirring for 10-20 minutes.

8. The method for protecting thin-film gallium arsenide solar cells in a hot and humid salt fog environment according to claim 1, characterized in that: In step (4), when the thin-film gallium arsenide solar cell monomer is left to stand in the organic silicon molecule hydrolysis solution, the thin-film gallium arsenide solar cell monomer is completely immersed in the organic silicon molecule hydrolysis solution; In the step (4), the thin-film gallium arsenide solar cell monomer is placed in the organic silicon molecule hydrolysis solution for 2 to 5 minutes. After being taken out, it is placed in a 50° C. constant-heat drying oven for 15 to 60 minutes.

9. The method for protecting thin-film gallium arsenide solar cells in a hot and humid salt fog environment according to claim 1, characterized in that: In step (5), resistance welding, soldering or conductive silver glue is used to connect the electrodes of each thin-film gallium arsenide solar cell monomer; In step (5), a negative pressure high temperature process with a temperature of 80° C. to 150° C. and a pressure of 50 KPa to 80 KPa is used to laminate the interconnected thin film gallium arsenide solar cell monomers and the packaging material to achieve packaging.

10. The method for protecting thin-film gallium arsenide solar cells in a hot and humid salt fog environment according to claim 1, characterized in that: The lower thin-film gallium arsenide solar cell is a GaInP2 / GaAs / InGaAs triple-junction thin-film gallium arsenide solar cell, and the back electrode of the thin-film gallium arsenide solar cell monomer is copper or Pt with a thickness of 10 to 50 μm.

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