A solar cell electrode and a preparation method thereof

Abstract

The present invention discloses a solar cell electrode and a preparation method thereof. First, conductive thin film layers are prepared on both the front and back sides of a substrate; second, patterned masks are prepared on partial regions of the two conductive thin film layers; third, a non-conductive protective layer is covered on the combination in the second step; fourth, the patterned masks and the protective layer covering the patterned masks are removed, and a metal conductive layer is prepared at the positions of the patterned masks; and the solar cell electrode is prepared by using this method. The manufacturing process of this method not only has low cost and cheap construction cost, but also simplifies the process, reduces waste liquid discharge, and can achieve the advantages of shortening working hours and reducing production costs.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic cell processing, and in particular to a composite solar cell electrode and a preparation method thereof. Background Art

[0002] At present, for crystalline silicon solar cells in the photovoltaic industry, the front surface electrode forms patterned silver grid lines by using the technology of screen printing silver paste and sintering. However, the electrode grid lines produced by this method have a small height-width ratio, resulting in a large light-shielding area of the battery; the residue of organic substances and structural defects in the paste after sintering lead to a large grid line resistance; moreover, silver is expensive and the sintering temperature is high (700 - 800 °C), which is not conducive to conversion efficiency and cost reduction.

[0003] However, after double-sided heterojunction (HIT) photovoltaic cells have gradually become the leader of future high-efficiency photovoltaic cells, traditional silver paste printing and high-temperature sintering are no longer applicable and cannot meet the component characteristics of heterojunction (HIT) photovoltaic cells. Indium Tin Oxide (ITO) thin film, as a transparent conductive film prepared from semiconductor materials, has many excellent physical properties such as high electrical conductivity, high visible light transmittance (greater than 90%), and anti-abrasion, as well as good chemical stability and some other semiconductor characteristics. It is easy to be fabricated into electrode patterns and has been widely used in double-sided heterojunction (HIT) photovoltaic cells. In applications, ITO needs to be made into a specific pattern to act as a transparent electrode for touch screens. The existing method for fabricating ITO usually first sputters a thin copper film on the ITO substrate as a seed layer, then uses the yellow light lithography process to transfer the circuit pattern to the photoresist dry film, and then conducts copper electroplating. Subsequently, the photoresist is removed and copper etching is carried out to corrode the previous thin copper film seed layer until the metal circuit pattern is exposed. Although the accuracy of the patterned circuit of this pattern fabrication method is high, due to the use of materials such as photoresist, photomask, and developer, the emissions are large, and environmental pollution will be caused during emissions; the cost and construction cost of using equipment such as photoresist coater, exposure machine, and developer are expensive, and the process steps are cumbersome, which is not conducive to mass production and cost reduction. Moreover, in the existing method for fabricating the pattern of the ITO film in double-sided heterojunction (HIT) photovoltaic cells, it is very easy to be affected by the characteristic that the ITO film reacts with acidic photosensitive materials (photoresist), resulting in damage to the ITO film and thus affecting the electrical properties of the photovoltaic cell. Therefore, it is necessary to further innovate and improve the method for fabricating patterns on the ITO film of heterojunction photovoltaic cells.

[0004] Therefore, the inventors of this invention patent aim to invent a solar cell electrode and a preparation method thereof for the above technical problems. Summary of the Invention

[0005] To overcome the above-mentioned drawbacks, the object of the present invention is to provide a solar cell electrode and a preparation method thereof.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a solar cell electrode, including a substrate, conductive thin film layers are provided on both the upper and lower sides of the substrate, and patterned masks are provided on both of the conductive thin film layers, and a non-conductive protective layer is covered around the combination of the substrate, the conductive thin film layers and the patterned mask, and the patterned mask can be replaced by a metal conductive layer, and the metal conductive layer can be in direct contact with the conductive thin film layer.

[0007] Preferably, the substrate is a HIT substrate, the conductive thin film layer is an ITO layer, and the protective layer is any one of silicon nitride, silicon or silicon oxide. That is, the preparation of the solar cell electrode on the patterned mask on the ITO film of the heterojunction photovoltaic cell is realized, and the selection of the protective layer material has good acid and alkali resistance while being non-conductive.

[0008] Preferably, at least one of the conductive thin film layers forms an isolation region with the edge of the substrate. The setting of the isolation region is to prevent the two conductive thin film layers of the substrate from being conducted.

[0009] Preferably, both sides of the patterned mask are serrated, and the radius of the R angle of the serration is not less than 0.05 mm. The serrated design can increase the adhesion of the metal conductive layer, and the design of not less than 0.05 mm can effectively cancel the internal stress generated during the thickening of the metal electrode preparation, and further increase the adhesion of the metal conductive layer.

[0010] Preferably, the metal conductive layer is in an inverted convex shape or a mushroom shape. The use of the inverted convex shape or the mushroom shape can effectively utilize the good support formed between the non-conductive protective layers, and increase the adhesion and stability of the metal conductive layer.

[0011] A preparation method of a solar cell electrode includes the following steps.

[0012] First, conductive thin film layers are prepared on both the front and back of the substrate.

[0013] Second, patterned masks are prepared on partial regions of the two conductive thin film layers.

[0014] Third, a non-conductive protective layer is covered on the combination in the second step.

[0015] Fourth, the patterned mask and the protective layer covering the patterned mask are removed, and a metal conductive layer is prepared at the position of the patterned mask.

[0016] Preferably, the conductive thin film layers in the first step can be prepared separately or simultaneously, and the conductive thin film layers in the first step are prepared by a medium-frequency pulsed magnetron sputtering process.

[0017] Preferably, the patterned mask in the second step is prepared by printing, and the patterned mask is further cured by thermal baking.

[0018] Preferably, the protective layer in the third step is prepared by vacuum sputtering.

[0019] Preferably, the patterned mask in the fourth step and the protective layer covering the patterned mask are removed by a hot water bath or a combination of a hot water bath / ultrasonic oscillation.

[0020] The beneficial effects of a solar cell electrode and a preparation method thereof according to the present invention are that the manufacturing process of this method is not only low in cost and inexpensive, but also the process is simplified, the waste liquid discharge is reduced, and the advantages of shortening the working hours and reducing the production cost can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a flow schematic diagram of a preparation method of a solar cell electrode.

[0022] Figure 2 For Figure 1 the top view of

[0023] Figure 3 It is a structural schematic diagram of a solar cell electrode.

[0024] Figure 4 It is a structural schematic diagram of a solar cell electrode before preparing the protective layer.

[0025] In the figure:

[0026] 1 - Substrate; 2 - Conductive thin film layer; 3 - Patterned mask; 4 - Protective layer; 5 - Metal conductive layer;

[0027] 21 - Isolation region. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0028] The following elaborates on the preferred embodiments of the present invention in conjunction with the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0029] See the attached Figures 1-4As shown in the figure, a solar cell electrode and its manufacturing method in this embodiment. The cell electrode includes a substrate 1, and conductive thin film layers 2 are provided on both the upper and lower sides of the substrate 1. Patterned masks 3 are provided on both of the two conductive thin film layers 2. A non-conductive protective layer 4 is covered around the combination of the substrate 1, the conductive thin film layer 2, and the patterned mask 3. The patterned mask 3 and the protective layer 4 on the patterned mask 3 can be replaced together by a metal conductive layer 5, and the metal conductive layer 5 can be in direct contact with the conductive thin film layer 2. The substrate 1 is a HIT substrate 1, the conductive thin film layer 2 is an ITO layer, and the protective layer 4 is any one of silicon nitride, silicon, or silicon oxide. The manufacturing method is as follows: on the front and back sides of the substrate 1, conductive thin film layers 2 are prepared; patterned masks 3 are prepared in partial areas on the two conductive thin film layers 2; a non-conductive protective layer 4 is covered on the combination in the previous step; the patterned mask 3 and the protective layer 4 covering the patterned mask 3 are removed, and a metal conductive layer 5 is prepared at the position of the patterned mask 3.

[0030] Among them, attached Figure 1 and 2 in, there are two steps 4. The first step 4 is a schematic diagram of removing the patterned mask 3, and the second step 4 is a schematic diagram of the metal conductive layer 5.

[0031] According to the structure of the above-mentioned solar cell electrode and its manufacturing method, the specific implementation manners are as follows.

[0032] The first embodiment of manufacturing a solar cell electrode

[0033] Step 1, on the front and back sides of the substrate 1 (HIT substrate 1) of the double-sided solar cell, a transparent conductive thin film layer 2 (ITO film) is prepared. The preparation of the transparent conductive thin film layer 2 in the double-sided heterojunction solar cell is a prior art and can be realized by an intermediate frequency pulsed magnetron sputtering process;

[0034] Step 2, in partial areas on the transparent conductive thin film layers 2 on the front and back sides of the double-sided solar cell, a patterned mask 3 is formed by printing respectively using a polymer material. The printing methods include screen printing technology or 3D printing technology;

[0035] Step 3, the patterned mask 3 formed on the transparent conductive thin film is cured by a thermal baking method to make the patterned mask 3 shrink to form a better aspect ratio. The thermal baking methods include oven method, tunnel furnace method, rapid annealing furnace, and direct or indirect hot air method;

[0036] Step 4, using vacuum sputtering method, silicon nitride or silicon oxide is respectively covered on the transparent conductive thin film layers 2 on the front and back sides of the double-sided solar cell and the cured patterned mask 3, and at the same time, the four sides of the substrate 1 are covered, that is, the protective layer 4 is covered comprehensively on the combination after step 3 is completed;

[0037] Step Five. Due to the water solubility of the polymer material, remove the patterned mask 3 on the transparent conductive thin film layer 2 and the silicon nitride or silicon oxide on the patterned mask 3 by means of a hot water bath or a combination of a hot water bath / ultrasonic oscillation, exposing the patterned transparent conductive thin film layer 2; since there is a strong adhesion between the silicon nitride or silicon oxide and the transparent conductive film, the silicon nitride or silicon oxide remaining on the transparent conductive thin film layer 2 serves as a mask for subsequent metallization processes.

[0038] Use screen printing technology to form a screen for the patterned mask 3 of the polymer material on the transparent conductive film. The mesh range of the screen is 200 - 500 meshes; the inner diameter width of the screen is between 15 - 19 um; the downward pressure of the squeegee is between 50 - 120 N; the distance between the screen and the surface of the battery cell is between 0.5 mm - 4 mm, and the screen printing effect is good.

[0039] The polymer material is a water-soluble peelable protective glue that can be printed, is soluble in water, does not chemically react with the transparent conductive film, and can be cured by heating. This polymer material is convenient for subsequent peeling and is a commonly used material in the photovoltaic cell industry.

[0040] In Step Three, the hot baking temperature is 100 - 150 °C, and the hot baking time is 10 - 20 minutes. The heating rate of the hot baking method is 10 - 30 °C / min. The heat energy provided during the heating process is relatively reduced, which can improve the excessive growth of film grains caused by heat energy.

[0041] In Step Five, the hot water bath includes direct or indirect hot water bath methods. The hot water bath temperature is 60 - 100 °C, and the hot water bath time is 10 - 30 minutes.

[0042] In Step Five, removing the patterned mask 3 on the transparent conductive thin film layer 2 and the silicon nitride or silicon oxide on the patterned mask 3 includes two methods: The first method is to place the double-sided solar photovoltaic cell in a flower basket and put it into a warm water tank for shaking or oscillation; the second method is to place the double-sided solar photovoltaic cell in a warm water tank and install a single-point or multi-point ultrasonic vibration source in the warm water tank. The multi-point ultrasonic vibration source is 2 - 20.

[0043] In the vacuum sputtering method of Step Four, at a temperature of 25 - 70 °C and a low plating rate of 1 - 5 nm / min, cover the front and back transparent conductive thin film layers 2 and the cured patterned mask 3 of the double-sided solar cell, as well as the four sides of the substrate 1 with silicon nitride or silicon oxide. The film thickness formed by the silicon nitride or silicon oxide is 40 - 90 nm. The film formed by the silicon nitride or silicon oxide effectively combines with the transparent conductive layer to form a better antireflection layer, which helps to improve the power generation efficiency of the photovoltaic cell.

[0044] Pattern the ITO film of the double-sided solar cell by the above method, only requiring materials such as water-soluble polymer materials, screen printing stencils, warm water, etc., and equipment such as screen printers, ovens, sputtering machines, etc. It has zero pollution emissions, low cost, cheap manufacturing cost, and simple processing steps, which can simplify the process, shorten the working hours and reduce the production cost.

[0045] The second embodiment of preparing the solar cell electrode

[0046] After step four in the first embodiment is completed, the double-sided solar cell covered with silicon nitride or silicon oxide is cured again by a thermal baking method. The thermal baking methods include oven method, tunnel furnace method, rapid annealing furnace and direct or indirect hot air method. The baking temperature is 100 - 150 °C, and the thermal baking time is 10 - 20 minutes. Make the patterned mask 3 on the transparent conductive thin film layer 2 shrink completely. The remaining steps are the same as those in the first specific embodiment.

[0047] That is, the second embodiment is cured twice, and cured twice respectively before and after preparing the protective layer 4 to make the patterned mask 3 shrink completely.

[0048] The above embodiments are only for explaining the technical concept and characteristics of the present invention, and the purpose is to let those who are familiar with this technology understand the content of the present invention and implement it, and cannot be used to limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. A solar cell, characterized in that: It includes a substrate (1), conductive thin film layers (2) are provided on both the upper and lower sides of the substrate (1), and patterned masks (3) are provided on both of the conductive thin film layers (2). A non-conductive protective layer (4) covers the periphery of the assembly composed of the substrate (1), the conductive thin film layers (2), and the patterned masks (3). The patterned masks (3) and the protective layer (4) on the patterned masks (3) can be replaced by a metal conductive layer (5). The specific replacement method is as follows: Remove the patterned masks (3) and the protective layer (4) covering the patterned masks (3) by means of a hot water bath or a combination of a hot water bath / ultrasonic oscillation, and prepare a metal conductive layer (5) at the position of the patterned masks (3). The metal conductive layer (5) can be in direct contact with the conductive thin film layer (2). The protective layer (4) is any one of silicon nitride or silicon oxide. Both sides of the patterned mask (3) are serrated, and the radius of the R corner of the serrations is not less than 0.05 mm. The metal conductive layer (5) has an inverted convex structure. The substrate (1) is a HIT substrate (1), and the conductive thin film layer (2) is an ITO layer.

2. The solar cell according to claim 1, wherein: At least one of the conductive thin film layers (2) forms an isolation region (21) with the edge of the substrate (1).

3. The preparation method of the solar cell according to claim 1, characterized in that: It includes the following steps First, prepare conductive thin film layers (2) on both the front and back of the substrate (1). Second, prepare patterned masks (3) in partial regions on both of the conductive thin film layers (2). Third, cover a non-conductive protective layer (4) on the assembly in the second step. Fourth, remove the patterned masks (3) and the protective layer (4) covering the patterned masks (3), and prepare a metal conductive layer (5) at the position of the patterned masks (3).

4. The preparation method of a solar cell according to claim 3, characterized in that: The conductive thin film layers (2) in the first step are prepared separately or simultaneously, and the conductive thin film layers (2) in the first step are prepared by means of a medium-frequency pulsed magnetron sputtering process.

5. The preparation method of a solar cell according to claim 3, characterized in that: The patterned masks (3) in the second step are prepared by a printing method, and the patterned masks (3) are also cured by thermal baking.

6. The preparation method of a solar cell according to claim 3, characterized in that: The protective layer (4) in the third step is prepared by a vacuum sputtering method.

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