A solar cell and a method of manufacturing the same

Abstract

The application discloses a solar cell and a preparation method thereof, and relates to the technical field of solar cells. The solar cell comprises a silicon substrate, a silicon oxide layer and an isolation glue layer which are sequentially stacked on the surface of the silicon substrate from inside to outside. The ratio of the thickness of the silicon oxide layer to the thickness of the isolation glue layer is 0.004-0.02, and the mass fraction of oxygen elements on the surface of the silicon oxide layer is greater than or equal to 51.4 wt%. The surface energy of the silicon oxide layer can be improved by the application, the bonding strength between the silicon oxide layer and the isolation glue layer is improved, and the failure conditions such as local warping, peeling and falling off of the isolation glue layer are improved.

Description

Technical Field

[0001] This invention relates to the field of solar cell technology, and in particular to a solar cell and its fabrication method. Background Technology

[0002] In the mass production process of solar cells, in order to reduce the carrier recombination rate on the cell surface and reduce optical reflection loss, a silicon oxide layer is usually prepared on the cell surface to achieve passivation and anti-reflection functions, thereby improving the photoelectric conversion efficiency of solar cells.

[0003] Because solar cells are thin and lightweight, and their surface functional films are relatively weak in resisting mechanical damage, they are easily damaged during production, storage, and transportation due to mechanical actions such as friction and impacts. This can lead to surface scratches, film wear, and localized damage, reducing the photoelectric conversion efficiency and yield of solar cells. Therefore, it is usually necessary to print an insulating adhesive layer on the surface of the silicon oxide layer to reduce the damage caused by mechanical actions such as friction and impacts to the surface of the solar cell and to achieve effective protection of the solar cell.

[0004] Currently, in the solar cell manufacturing process, after the silicon oxide layer is deposited, it often requires post-processing steps such as annealing, cleaning, and drying before an insulating adhesive layer is prepared on the surface of the silicon oxide layer. However, these post-processing steps reduce the surface energy and surface activity of the silicon oxide layer, resulting in poor surface wettability. This leads to reduced adhesion between the insulating adhesive layer and the silicon oxide layer, making the insulating adhesive layer prone to localized lifting, peeling, and detachment during the subsequent production, storage, and transportation of solar cells. This reduces the protective effect on the cells and ultimately causes a decrease in the photoelectric conversion efficiency and an increase in the product defect rate of the solar cells. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a solar cell and a method for preparing the same, which can improve the surface energy of the silicon oxide layer and enhance the bonding strength between the silicon oxide layer and the insulating adhesive layer.

[0006] To solve the above-mentioned technical problems, the present invention provides a solar cell, including a silicon substrate, and a silicon oxide layer and an insulating adhesive layer sequentially stacked on the surface of the silicon substrate from the inside to the outside; The ratio of the thickness of the silicon oxide layer to the thickness of the insulating adhesive layer is 0.004~0.02; The mass fraction of oxygen on the surface of the silicon oxide layer is ≥51.4 wt%.

[0007] As an improvement to the above technical solution, the mass fraction of oxygen on the surface of the silicon oxide layer is 53wt%~60wt%.

[0008] As an improvement to the above technical solution, the surface energy of the silicon oxide layer is >45mN / m.

[0009] As an improvement to the above technical solution, the surface energy of the silicon oxide layer is 48mN / m to 70mN / m.

[0010] As an improvement to the above technical solution, the thickness of the silicon oxide layer is 20nm~50nm.

[0011] As an improvement to the above technical solution, the silicon substrate has a light-receiving surface and a backlight-receiving surface arranged opposite to each other, and the silicon oxide layer and the insulating adhesive layer are both stacked on the light-receiving surface of the silicon substrate.

[0012] As an improvement to the above technical solution, the insulating adhesive layer includes a plurality of insulating adhesive strips, which are spaced apart along a first direction and extend along a second direction. The first direction and the second direction are arranged to intersect each other.

[0013] As an improvement to the above technical solution, in the first direction, the insulating strip includes a protective part and an extension part, both of which cover the surface of the silicon oxide layer; The protective part is connected to the extension part on opposite sides in the first direction to form a continuous integral structure on the top surface; The distance from the highest point of the protective part to the surface of the silicon oxide layer is H1, and the distance from the highest point of the extended part to the surface of the silicon oxide layer is H2, wherein H1 > H2; The thickness of the insulating adhesive layer is equal to the distance from the highest point of the protective part to the surface of the silicon oxide layer.

[0014] As an improvement to the above technical solution, the distance H1 from the highest point of the protective part to the surface of the silicon oxide layer is 3μm~6μm; and / or, The distance H2 from the highest point of the extended portion to the surface of the silicon oxide layer is ≤1μm.

[0015] As an improvement to the above technical solution, in the first direction, the total width of the insulating strip is W1, and the width of the protective part is W2, wherein: 0.5W1≤W2≤0.7W1.

[0016] As an improvement to the above technical solution, the top surface of the protective part is a convex arc surface, and the top surface of the protective part and the top surface of the extension part are smoothly transitioned.

[0017] As an improvement to the above technical solution, along the second direction, the insulating strip includes a first insulating part and a second insulating part that are connected to each other; The total width of the first isolation section in the first direction is W 11 The total width of the second isolation section in the first direction is W 12 Among them, W 12 >W 11 .

[0018] As an improvement to the above technical solution, 1.2W 11 <W 12 ≤2.5W 11 ; In the formula, W 11 W is the total width of the first isolation section in the first direction. 12 The total width of the second isolation section in the first direction.

[0019] As an improvement to the above technical solution, both the first isolation section and the second isolation section include the protective section and the extension section; In the first direction, the total width W of the first isolation section 11 The width of the protective portion in the first isolation section is 0.45mm to 0.55mm, and the width of the protective portion is 0.25mm to 0.35mm. In the first direction, the total width W of the second isolation section 12 The width of the protective part in the second isolation section is 0.3mm to 0.7mm, and the width of the protective part is 0.55mm to 1mm.

[0020] As an improvement to the above technical solution, along the second direction, the surface of the silicon oxide layer includes an edge region and a middle region, and the edge region is disposed on at least one side of the middle region in the second direction; The first isolation portion is stacked on the surface of the middle region, and the second isolation portion is stacked on the surface of the edge region.

[0021] Accordingly, the present invention also provides a method for preparing a solar cell, comprising the following steps: (1) Provide a silicon substrate; (2) A silicon oxide layer is deposited on the surface of the silicon substrate; (3) The surface of the silicon oxide layer is subjected to an oxygen-enriched treatment to ensure that the mass fraction of oxygen on the surface of the silicon oxide layer is ≥51.4 wt%; (4) An isolation adhesive layer is formed on the surface of the silicon oxide layer.

[0022] As an improvement to the above technical solution, in step (3), the oxygen-enriched treatment of the surface of the silicon oxide layer includes one or more of the following methods: plasma activation, UV-O3 treatment, wet oxygen-enriched oxidation, ozone water oxidation, and dry oxygen oxidation.

[0023] As an improvement to the above technical solution, in step (3), the surface of the silicon oxide layer is treated with oxygen enrichment by plasma activation. The plasma activation method has a radio frequency power of 100W~300W, a gas pressure of 0.5~1.5Torr, a frequency of 10MHz~15MHz, a processing time of 60s~120s, and a gas flow rate of 20sccm~100sccm.

[0024] As an improvement to the above technical solution, in step (3), the surface of the silicon oxide layer is treated with oxygen enrichment by UV-O3 treatment method. When the surface of the silicon oxide layer is subjected to oxygen-enriched treatment using the UV-O3 method, the wavelength of the ultraviolet light source is 254 nm and the intensity is 50 mW / cm². 2 ~100mW / cm 2 The processing time is 10 seconds to 2 minutes.

[0025] As an improvement to the above technical solution, in step (4), the isolation adhesive layer is formed on the surface of the silicon oxide layer by inkjet printing or screen printing.

[0026] As an improvement to the above technical solution, the release adhesive layer is formed on the surface of the silicon oxide layer using inkjet printing, including the following steps: (4.1) Apply a release adhesive to the surface of the silicon oxide layer in a predetermined area using a spray nozzle; (4.2) Curing the release adhesive to form a release adhesive layer.

[0027] As an improvement to the above technical solution, in step (4.1), the distance between the bottom end of the nozzle and the surface of the silicon oxide layer is 5mm~10mm.

[0028] As an improvement to the above technical solution, in step (4.2), the release adhesive is cured by irradiation with an ultraviolet light source to form a release adhesive layer; The ultraviolet light source has a wavelength of 365 nm, a curing time of 0.6~0.7 s, and an energy density of 3000 mJ / cm². 2 ~6000mJ / cm 2 The rated luminous intensity of the UV light source is 11000mW / cm². 2 .

[0029] Implementing this invention has the following beneficial effects: 1. This invention, by synergistically regulating the thickness ratio of the silicon oxide layer to the separator layer to be 0.004~0.02 and controlling the oxygen content on the surface of the silicon oxide layer to be ≥51.4wt%, can effectively improve the oxygen enrichment on the surface of the silicon oxide layer, promote the generation of more oxygen-related polar groups on its surface, thereby significantly improving the surface energy of the silicon oxide layer, optimizing the wetting and spreading effect of the separator layer on its surface, strengthening the chemical bonding and interfacial coupling between the separator layer and the silicon oxide layer, thereby improving the adhesion strength between the separator layer and the silicon oxide layer, improving the failure of the separator layer such as local lifting, peeling, and detachment, ensuring the structural stability and photoelectric transmission performance of solar cells, and ultimately achieving a simultaneous improvement in photoelectric conversion efficiency and product yield.

[0030] 2. Through the structural design of the protective and extended sections in the insulating strip, the insulating strip forms an integrated structure with a higher center and lower sides in the first direction. The higher protective section in the middle provides good support and protection, reducing mechanical damage such as wear and impacts to the battery surface. The thinner extended sections on both sides increase the effective contact area between the insulating strip and the silicon oxide layer, providing more bonding sites and enhancing interfacial adhesion. In addition, the thinner extended sections on both sides of the insulating strip reduce the blocking effect of the insulating strip on incident light, reducing optical loss, thereby further improving the photoelectric conversion efficiency and yield of the solar cell. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of a solar cell according to an embodiment of the present invention; Figure 2 yes Figure 1 A top view of the solar cell shown. Figure 3 This is a schematic diagram of the structure of a solar cell according to another embodiment of the present invention; Figure 4 yes Figure 3 The diagram shows an enlarged view of the solar cell at the insulating strip. Figure 5 This is a schematic diagram of the structure of a solar cell according to another embodiment of the present invention; Figure 6 yes Figure 5 A magnified view of a portion of the solar cell at point S shown. The components include: silicon substrate 1, silicon oxide layer 2, isolation adhesive layer 3, edge region 21, middle region 22, isolation strip 31, protective part 311, extension part 312, first isolation part 313, and second isolation part 314. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0033] In this document, terms such as "first" and "second" serve only as a non-exhaustive enumeration and should be understood as not constituting a closed limitation on the quantity. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include at least one of those features. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0034] In the description of this application, "a number" means at least one, such as one, two, etc., unless otherwise expressly and specifically defined.

[0035] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0036] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0037] Unless otherwise specified, the percentage content mentioned in this application refers to mass percentage for solid-liquid mixtures and solid-phase-solid mixtures, and volume percentage for liquid-phase-liquid mixtures.

[0038] Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Raw materials whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0039] like Figure 1 As shown, the present invention provides a solar cell, including a silicon substrate 1, and a silicon oxide layer 2 and an insulating adhesive layer 3 sequentially stacked on the surface of the silicon substrate 1 from the inside to the outside; The ratio of the thickness of the silicon oxide layer 2 to the thickness of the insulating adhesive layer 3 is 0.004~0.02; The mass fraction of oxygen on the surface of the silicon oxide layer 2 is ≥51.4 wt%.

[0040] It should be noted that post-treatment processes such as annealing, cleaning, and drying can easily lead to a significant loss of oxygen-related polar groups (such as Si-OH) on the surface of silicon oxide layer 2, and may be accompanied by the formation of local oxygen vacancies on the surface. This results in a reduction of effective oxygen active sites on the surface of silicon oxide layer 2, significantly decreasing surface energy and interfacial activity. This directly weakens the wetting and spreading properties of the release liner on the surface of silicon oxide layer 2, weakens the hydrogen bonding and chemical coupling effects between the release liner and silicon oxide layer 2, causing a decrease in interfacial adhesion strength. Ultimately, this makes the release liner layer 3 prone to interfacial failure problems such as localized lifting, peeling, or even detachment during subsequent processes or use.

[0041] This invention, by synergistically regulating the thickness ratio of silicon oxide layer 2 to separator layer 3 (0.004~0.02) and controlling the oxygen content on the surface of silicon oxide layer 2 to be ≥51.4wt%, effectively enhances the oxygen enrichment on the surface of silicon oxide layer 2, promoting the generation of more oxygen-related polar groups (such as Si-OH). This significantly increases the surface energy of silicon oxide layer 2, optimizes the wetting and spreading effect of separator layer 3 on its surface, strengthens the chemical bonding and interfacial coupling between separator layer 3 and silicon oxide layer 2, thereby improving the adhesion strength between separator layer 3 and silicon oxide layer 2, improving the failure of separator layer 3 such as localized lifting, peeling, and detachment, ensuring the structural stability and photoelectric transmission performance of solar cells, and ultimately achieving a simultaneous improvement in photoelectric conversion efficiency and product yield.

[0042] To further clarify, the ratio of the thickness of the silicon oxide layer 2 to the thickness of the separator layer 3 is controlled within the range of 0.004 to 0.02. If the ratio is too small, it indicates that the silicon oxide layer 2 is relatively too thin and the separator layer 3 is relatively too thick. A thin silicon oxide layer 2 has a limited total number of polar bonding sites (such as Si-OH), resulting in a lower increase in bonding strength. Furthermore, an excessively thick separator layer 3 is prone to warping and deformation during heat treatment or subsequent processes, further increasing the risk of peeling. Additionally, an excessively thick separator layer 3 also leads to decreased light transmittance, reducing the photoelectric conversion efficiency of the solar cell. Conversely, if the ratio is too large, the silicon oxide layer 2 is relatively too thick and the separator layer 3 is relatively too thin. An excessively thick silicon oxide layer 2 is prone to introducing internal stress or structural defects, increasing carrier recombination centers and affecting the battery's electrical performance; while an excessively thin separator layer 3 reduces its protective effect on the battery.

[0043] Furthermore, if the mass fraction of oxygen on the surface of silicon oxide layer 2 is less than 51.4 wt%, there will be insufficient oxygen-related polar groups (such as Si-OH) to be generated on the surface of silicon oxide layer 2. This results in insufficient adhesion strength between the release liner layer 3 and silicon oxide layer 2, and poor improvement effect on failures such as localized lifting, peeling, and detachment of the release liner layer 3. Specifically, the mass fraction of oxygen on the surface of silicon oxide layer 2, i.e., the oxygen content on the surface of silicon oxide layer 2, can be measured by methods such as X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), or secondary ion mass spectrometry (SIMS).

[0044] In some embodiments, the surface energy of the silicon oxide layer 2 is >45mN / m.

[0045] In this embodiment, the silicon oxide layer 2 has high surface energy, strong surface polarity, and high activity, which makes the wettability of the isolation adhesive layer 3 on the surface of the silicon oxide layer 2 good and the interfacial bonding force strong, thereby improving the adhesion and bonding strength of the isolation adhesive layer 3.

[0046] In some embodiments, the thickness of the silicon oxide layer 2 is 20nm to 50nm. By controlling the thickness of the silicon oxide layer 2 to be 20nm to 50nm, the loss of oxygen-related polar groups (such as Si-OH) on the surface of the silicon oxide layer 2 can be reduced during post-processing steps such as annealing, cleaning, and drying. This maintains a high oxygen content and surface energy on the surface of the silicon oxide layer 2. Furthermore, after subsequent oxygen enrichment treatment, the oxygen content on the surface of the silicon oxide layer 2 can be further increased, ensuring that the silicon oxide layer 2 forms a state with high surface oxygen content and high surface energy after oxygen enrichment treatment. This effectively improves the adhesion and bonding strength between the release adhesive layer 3 and the silicon oxide layer 2, preventing the release adhesive layer 3 from failing.

[0047] In some embodiments, the silicon substrate 1 has a light-receiving surface and a back-lighting surface disposed opposite to each other, and the silicon oxide layer 2 and the insulating adhesive layer 3 are both stacked on the light-receiving surface of the silicon substrate 1. Specifically, the light-receiving surface of the silicon substrate 1 is the front side of the silicon substrate 1, and the back-lighting surface of the silicon substrate 1 is the back side of the silicon substrate 1.

[0048] By providing a silicon oxide layer 2 on the light-receiving surface of the silicon substrate 1, the carrier recombination rate on the cell surface can be reduced, optical reflection loss can be decreased, and the photoelectric conversion efficiency of the cell can be improved. At the same time, an insulating adhesive layer 3 is provided on the surface of the silicon oxide layer 2, which can protect the light-receiving surface of the solar cell, reduce the damage to the light-receiving surface of the solar cell during production, storage and transportation, and ensure that the solar cell has good photoelectric conversion efficiency and product yield.

[0049] In one embodiment, the solar cell of the present invention is a back-contact cell.

[0050] In some embodiments, the insulating adhesive layer 3 includes a plurality of insulating adhesive strips 31, which are spaced apart along a first direction and extend along a second direction; the first direction and the second direction are intersecting each other.

[0051] It is worth noting that the spacing between adjacent insulating strips can be adjusted according to actual conditions to achieve better battery protection and light absorption utilization. In some embodiments, the spacing between adjacent insulating strips can be adjusted so that the total coverage area of ​​all insulating strips in the insulating layer is 25% to 65% of the area of ​​the light-receiving surface of the solar cell.

[0052] Furthermore, the isolation strip 31 in this invention can be implemented in various ways. The isolation strip 31 can be set with a single width, or it can be set with partial widening, or it can be set with partial thinning. The invention is further illustrated below with specific embodiments: Example 1 This embodiment provides a solar cell, including a silicon substrate 1, and a silicon oxide layer 2 and an insulating adhesive layer 3 sequentially stacked on the surface of the silicon substrate 1 from the inside to the outside; The ratio of the thickness of the silicon oxide layer 2 to the thickness of the isolation adhesive layer 3 is 0.004 to 0.02, specifically 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.011, 0.012, 0.013, 0.014, 0.015, 0.016, 0.017, 0.018, 0.019, 0.02, etc., but not limited to these; the ratio of the thickness of the silicon oxide layer 2 to the thickness of the isolation adhesive layer 3 is preferably 0.006 to 0.015, and more preferably 0.006 to 0.01.

[0053] The mass fraction of oxygen on the surface of the silicon oxide layer 2 is ≥51.4 wt%. Preferably, the mass fraction of oxygen on the surface of the silicon oxide layer 2 is 51.4 wt% to 63 wt%. Within the above range, more polar groups such as Si-OH can be formed on the surface of the silicon oxide layer 2, which can improve the surface energy and interfacial wettability, thereby reducing the risk of defects such as lifting, peeling and falling off of the release liner layer 3. Specifically, it can be 51.4 wt%, 52 wt%, 53 wt%, 54 wt%, 55 wt%, 56 wt%, 57 wt%, 58 wt%, 59 wt%, 60 wt%, 61 wt%, 62 wt%, 63 wt%, etc., but is not limited to these. The mass fraction of oxygen on the surface of the silicon oxide layer 2 is further preferably 53 wt% to 60 wt%.

[0054] In some embodiments, the surface energy of the silicon oxide layer 2 is 48 mN / m to 70 mN / m, which is beneficial for further improving the adhesion of the release liner 3 and further enhancing the bonding strength between the release liner 3 and the silicon oxide layer 2. Specifically, it can be 48 mN / m, 50, 52, 55, 58, 60, 62, 65, 68, 70 mN / m, etc., but is not limited to these. More preferably, the surface energy of the silicon oxide layer 2 is 50 mN / m to 65 mN / m.

[0055] In this embodiment, the thickness of the isolation adhesive layer 3 is 3μm to 6μm, specifically 3μm, 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm, 6μm, etc., but is not limited to these.

[0056] In this embodiment, the thickness of the silicon oxide layer 2 is 20nm to 50nm, and can be 20nm, 22nm, 25nm, 28nm, 30nm, 32nm, 35nm, 38nm, 40nm, 42nm, 45nm, 48nm, or 50nm, but is not limited thereto. Preferably, the thickness of the silicon oxide layer 2 is 25nm to 45nm.

[0057] In this embodiment, both the silicon oxide layer 2 and the insulating adhesive layer 3 are stacked on the light-receiving surface of the silicon substrate 1.

[0058] like Figure 2 As shown, in this embodiment, the insulating adhesive layer 3 includes a plurality of insulating adhesive strips 31, which are spaced apart along a first direction and extend along a second direction; the first direction and the second direction intersect each other. Specifically, the first direction may be the direction of the insulating adhesive strip 31 in width, and the second direction may be the direction of the insulating adhesive strip 31 in length.

[0059] In this embodiment, by using a number of insulating strips 31, the surface of the solar cell is protected. Compared with a continuous, fully covered insulating film, the spaced insulating strips 31 can significantly reduce the area of ​​incident light blockage, increase the effective absorption of light by the solar cell, and further improve the photoelectric conversion efficiency of the solar cell.

[0060] The width of the isolation strip 31 is 0.45mm to 0.55mm, specifically 0.45mm, 0.46mm, 0.47mm, 0.48mm, 0.49mm, 0.50mm, 0.51mm, 0.52mm, 0.53mm, 0.54mm, 0.55mm, etc., but is not limited to these.

[0061] In this embodiment, by optimizing the thickness ratio of the silicon oxide layer 2 to the separator layer 3, controlling the oxygen content on the surface of the silicon oxide layer 2, and using spaced separator strips 31 to form the separator layer 3, the bonding strength between the separator strips 31 and the silicon oxide layer 2 can be effectively improved, and the failure problems such as local lifting, peeling, and detachment of the separator layer 3 can be improved. This reduces the debonding rate of the separator layer 3 from the original 1%~3% to 0.1%~0.5%, and ultimately improves the photoelectric conversion efficiency of the battery by 0.005%~0.025%.

[0062] Example 2 like Figure 3 and Figure 4 As shown, this embodiment provides a solar cell. Unlike embodiment 1, in this embodiment, in the first direction, the insulating strip 31 includes a protective part 311 and an extension part 312, both of which cover the surface of the silicon oxide layer 2. The protective part 311 is connected to the extension part 312 on opposite sides in the first direction to form an integral structure with a continuous top surface. The distance from the highest point of the protective part 311 to the surface of the silicon oxide layer 2 is H1, and the distance from the highest point of the extension part 312 to the surface of the silicon oxide layer 2 is H2, wherein H1 > H2; The thickness of the isolation adhesive layer 3 is equal to the distance from the highest point of the protective part 311 to the surface of the silicon oxide layer 2, that is, the thickness of the isolation adhesive layer 3 is equal to H1.

[0063] In this embodiment, the structural design of the protective part 311 and the extension part 312 enables the insulating strip 31 to form an integrated structure with a higher center and lower sides in the first direction. The higher protective part 311 provides good support and protection, reducing mechanical damage such as wear and impacts on the battery surface. The thinner extension parts 312 on both sides increase the effective contact area between the insulating strip 31 and the silicon oxide layer 2, providing more bonding sites and enhancing interfacial adhesion. Simultaneously, the thinner extension parts 312 reduce internal stress during curing and high-temperature processes, avoiding problems such as warping and peeling caused by stress concentration. Furthermore, the thinner extension parts 312 reduce the shading effect of the edge area of ​​the insulating strip 31 on incident light, reducing optical loss, thereby further improving the photoelectric conversion efficiency and yield of the solar cell.

[0064] In some embodiments, the distance H1 from the highest point of the protective portion 311 to the surface of the silicon oxide layer 2 is 3μm to 6μm, and the distance H2 from the highest point of the extended portion 312 to the surface of the silicon oxide layer 2 is ≤1μm. When H1 and H2 are within the above ranges, reliable protection can be provided to the battery surface, and interface failure problems such as localized lifting, peeling, and detachment of the insulating strip 31 can be further improved, thereby enhancing the stability of the interface adhesion.

[0065] Specifically, the distance H1 from the highest point of the protective part 311 to the surface of the silicon oxide layer 2 can be 3μm, 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm, 6μm, etc., but is not limited to this. The distance H2 from the highest point of the extension part 312 to the surface of the silicon oxide layer 2 can be 1μm, 0.9μm, 0.8μm, 0.7μm, etc., but is not limited to this.

[0066] In some embodiments, in the first direction, the total width of the insulating strip 31 is W1, and the width of the protective portion 311 is W2, wherein: 0.5W1≤W2≤0.7W1.

[0067] The total width W1 of the insulating strip 31 and the width W2 of the protective part 311 satisfy the above formula, ensuring that reliable protection can be formed on the battery surface.

[0068] In this embodiment, the total width W1 of the isolation strip 31 is 0.45mm~0.55mm, specifically it can be 0.45mm, 0.46mm, 0.47mm, 0.48mm, 0.49mm, 0.50mm, 0.51mm, 0.52mm, 0.53mm, 0.54mm, 0.55mm, etc., but is not limited to these.

[0069] In this embodiment, the width W2 of the protective part 311 is 0.25mm to 0.35mm, specifically it can be 0.25mm, 0.26mm, 0.27mm, 0.28mm, 0.29mm, 0.30mm, 0.31mm, 0.32mm, 0.33mm, 0.34mm, 0.35mm, etc., but is not limited to these.

[0070] In one embodiment, the top surface of the protective part 311 is a convex arc surface, and the top surface of the protective part 311 smoothly transitions with the top surface of the extension part 312.

[0071] The protective part 311 has a convex arc surface structure, which can reduce specular reflection of incident light, reduce optical loss, and improve the battery's light absorption and utilization rate. At the same time, the top surface of the protective part 311 and the top surface of the extension part 312 form a smooth transition integral curved surface, which can reduce the adhesion and accumulation of impurities, avoid the obstruction of incident light by the adhesion and accumulation of impurities, and further reduce optical loss.

[0072] Example 3 like Figure 5 and Figure 6 As shown, this embodiment provides a solar cell, which differs from Embodiment 2 in that, along the second direction, the insulating strip 31 includes a first insulating portion 313 and a second insulating portion 314 that are interconnected. The total width of the first isolation section 313 in the first direction is W 11 The total width of the second isolation section 314 in the first direction is W. 12 Among them, W 12 >W 11 .

[0073] In this embodiment, the insulating strip 31 includes a first insulating portion 313 and a second insulating portion 314 with different widths. This locally widens the insulating strip 31, increasing the contact area between the insulating strip 31 and the silicon oxide layer 2, further enhancing the adhesion strength between them and making the insulating strip 31 less prone to detachment. Simultaneously, it avoids the overall widening of the insulating strip 31, which could lead to severe optical loss. Furthermore, the locally widened insulating strip provides better battery protection.

[0074] In some implementations, 1.2W 11 <W 12 ≤2.5W 11 ; In the formula, W 11 W is the total width of the first isolation section 313 in the first direction. 12 The total width of the second isolation section 314 in the first direction.

[0075] In some embodiments, both the first isolation portion 313 and the second isolation portion 314 include the protective portion 311 and the extension portion 312; In this embodiment, in the first direction, the total width W of the first isolation portion 313 is... 11 The thickness is 0.45mm to 0.55mm, specifically 0.45mm, 0.46mm, 0.47mm, 0.48mm, 0.49mm, 0.50mm, 0.51mm, 0.52mm, 0.53mm, 0.54mm, 0.55mm, etc., but is not limited to these.

[0076] In this embodiment, in the first direction, the width of the protective portion 311 in the first isolation portion 313 is 0.25mm to 0.35mm, specifically it can be 0.25mm, 0.26mm, 0.27mm, 0.28mm, 0.29mm, 0.30mm, 0.31mm, 0.32mm, 0.33mm, 0.34mm, 0.35mm, etc., but is not limited to these.

[0077] In this embodiment, in the first direction, the total width W of the second isolation portion 314 is... 12 The width of the protective portion 311 in the second isolation portion 314 is 0.3mm to 0.7mm, specifically 0.3mm, 0.35mm, 0.4mm, 0.45mm, 0.5mm, 0.55mm, 0.9mm, 0.95mm, 1mm, etc., but is not limited to these.

[0078] In one embodiment, along the second direction, the surface of the silicon oxide layer 2 includes an edge region 21 and an intermediate region 22, wherein the edge region 21 is disposed on at least one side of the intermediate region 22 in the second direction; The first isolation portion 313 is stacked on the surface of the middle region 22, and the second isolation portion 314 is stacked on the surface of the edge region 21.

[0079] During production, storage and transportation, the edge area 21 of the solar cell is more susceptible to scratches or bumps. Therefore, the second isolation part 314 is provided on the edge area 21 of the silicon oxide layer 2 surface, which can further reduce the damage to the surface of the cell caused by mechanical action such as friction and bumps, and further enhance the protection of the cell.

[0080] In this embodiment, in the second direction, the length of the first isolation portion 313 is greater than the length of the second isolation portion 314, which can further reduce optical loss. In some embodiments, the length of the first isolation portion 313 is 4 to 12 times the length of the second isolation portion 314, specifically 4, 5, 6, 7, 8, 9, 10, 11, 12, etc., but is not limited thereto.

[0081] Example 4 This invention also discloses a method for preparing a solar cell, used to prepare the solar cell described in any one of Examples 1-3, comprising the following steps: (1) Provide a silicon substrate 1; (2) A silicon oxide layer 2 is deposited on the surface of the silicon substrate 1; (3) The surface of the silicon oxide layer 2 is subjected to oxygen enrichment treatment so that the mass fraction of oxygen on the surface of the silicon oxide layer 2 is ≥51.4 wt%; (4) An isolation adhesive layer 3 is formed on the surface of the silicon oxide layer 2.

[0082] It is worth noting that by enriching the surface of the silicon oxide layer 2 with oxygen, the present invention can increase the oxygen content on the surface of the silicon oxide layer 2, thereby enriching the surface of the silicon oxide layer 2 with a large number of polar functional groups such as Si-OH, effectively improving the surface energy and interfacial wettability of the silicon oxide layer 2, thus enhancing the wetting and spreading effect of the release adhesive on its surface, strengthening the interfacial coupling and chemical bonding between the release adhesive layer 3 and the silicon oxide layer 2, improving the interfacial adhesion strength, and improving the failure problems such as local lifting, peeling, and detachment of the release adhesive layer 3. The proportion of release adhesive layer 3 debonding can be reduced from the original 1%~3% to 0.1%~0.5%.

[0083] In some embodiments, after the silicon oxide layer 2 is deposited, it needs to be annealed, cleaned, and dried to form a dense and cured film structure, optimize passivation performance, and remove surface impurities. However, annealing, cleaning, and drying will reduce the thickness of the silicon oxide layer 2 and reduce the oxygen content on the surface of the silicon oxide layer 2, which will significantly reduce the surface energy of the silicon oxide layer 2. The present invention can increase the oxygen content on the surface of the silicon oxide layer 2 to ≥51.4wt% by performing an oxygen-enriching treatment on the surface of the silicon oxide layer 2, thereby effectively increasing the surface energy of the silicon oxide layer 2 and improving the bonding strength between the release adhesive layer 3 and the silicon oxide layer 2.

[0084] In some embodiments, in step (3), the oxygen enrichment treatment of the surface of the silicon oxide layer 2 includes one or more of the following methods: plasma activation, UV-O3 treatment, wet oxygen enrichment oxidation, ozone water oxidation, and dry oxygen oxidation.

[0085] In this invention, one or more of the following methods are used to perform oxygen enrichment treatment on the surface of silicon oxide layer 2: plasma activation, UV-O3 treatment, wet oxygen-enriched oxidation, ozone water oxidation, and dry oxygen oxidation. This can repair oxygen vacancies on the surface of silicon oxide layer 2 and generate a large number of Si-OH polar hydroxyl groups, effectively increasing the oxygen content and surface energy of the surface of silicon oxide layer 2, improving the wetting and spreading performance of the release adhesive on the surface of silicon oxide layer 2, and thus enhancing the interfacial bonding strength.

[0086] Specifically, plasma activation can utilize radio frequency or microwave excitation of O2, O2 / H2O mixed gas, or N2O to generate highly reactive oxygen free radicals, ozone, etc., thereby generating Si-OH polar groups on the surface of silicon oxide layer 2 and increasing the oxygen content of the silicon oxide layer 2 surface. UV-O3 treatment, also known as ultraviolet ozone treatment, can photolyze O2 under ultraviolet light to generate O3 and oxygen free radicals, thus generating Si-OH polar groups on the surface of silicon oxide layer 2. Wet oxygen-enriched oxidation, also called wet chemical oxidation, uses a strong oxidizing solution to break the Si-O-Si bonds on the surface of silicon oxide layer 2, generating high-density Si-OH. Ozone water oxidation slowly oxidizes the surface of silicon oxide layer 2 by dissolving ozone in an aqueous phase, generating Si-OH polar groups. Dry oxygen oxidation allows oxygen molecules to diffuse into the silicon oxide surface in a high-temperature, high-purity oxygen atmosphere, replenishing oxygen vacancies and increasing the surface oxygen content.

[0087] In some embodiments, in step (3), the oxygen-enriching treatment of the surface of the silicon oxide layer 2 is performed by plasma activation. The plasma activation method has a radio frequency power of 100W~300W, a gas pressure of 0.5~1.5Torr, a frequency of 10MHz~15MHz, a processing time of 60s~120s, and a gas flow rate of 20sccm~100sccm.

[0088] Specifically, the gas is O2, an O2 / H2O mixture, or N2O.

[0089] In some embodiments, in step (3), the surface of the silicon oxide layer 2 is subjected to oxygen enrichment treatment by UV-O3 treatment. When the surface of the silicon oxide layer 2 is subjected to oxygen enrichment treatment using the UV-O3 method, the wavelength of the ultraviolet light source is 254 nm and the intensity is 50 mW / cm². 2 ~100mW / cm 2 The processing time is 10 seconds to 2 minutes.

[0090] In one embodiment, when the surface of the silicon oxide layer 2 is treated with oxygen enrichment using the UV-O3 treatment method, it can be combined with ozone water immersion, with an ozone concentration of 20 mg / L to 100 mg / L.

[0091] In some embodiments, in step (4), the insulating adhesive layer 3 is formed on the surface of the silicon oxide layer 2 by inkjet printing or screen printing.

[0092] In some embodiments, the insulating adhesive layer 3 is formed on the surface of the silicon oxide layer 2 by inkjet printing, including the following steps: (4.1) Apply a release adhesive to the surface of the preset area of ​​the silicon oxide layer 2 through a nozzle; (4.2) Cure the release adhesive to form release adhesive layer 3.

[0093] In this embodiment, the isolation adhesive layer 3 is formed on the surface of the silicon oxide layer 2 by inkjet printing. Inkjet printing does not involve mechanical pressure contact, so it will not scratch or damage the silicon oxide layer 2, nor will it destroy the Si-OH polar groups and high surface energy state formed on the surface of the silicon oxide layer 2 by oxygen enrichment treatment. This is beneficial to maintaining the bonding strength between the isolation adhesive layer 3 and the silicon oxide layer 2, and reducing the problems of lifting, peeling and detachment caused by interface damage.

[0094] In some embodiments, in step (4.1), the distance between the bottom end of the nozzle and the surface of the silicon oxide layer 2 is 5 mm to 10 mm. Controlling the distance between the bottom end of the nozzle and the surface of the silicon oxide layer 2 within a limited range is beneficial for achieving precise molding.

[0095] In some embodiments, in step (4.2), the release adhesive is cured by irradiation with an ultraviolet light source to form a release adhesive layer 3; The ultraviolet light source has a wavelength of 365 nm, a curing time of 0.6~0.7 s, and an energy density of 3000 mJ / cm². 2 ~6000mJ / cm 2 The rated luminous intensity of the UV light source is 11000mW / cm². 2 .

[0096] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A solar cell, characterized in that, It includes a silicon substrate, and a silicon oxide layer and a release adhesive layer stacked sequentially from the inside to the outside on the surface of the silicon substrate; The ratio of the thickness of the silicon oxide layer to the thickness of the insulating adhesive layer is 0.004~0.02; The mass fraction of oxygen on the surface of the silicon oxide layer is ≥51.4 wt%.

2. The solar cell according to claim 1, characterized in that, The mass fraction of oxygen on the surface of the silicon oxide layer is 53wt%~60wt%.

3. The solar cell according to claim 1, characterized in that, The surface energy of the silicon oxide layer is >45mN / m.

4. The solar cell according to claim 3, characterized in that, The surface energy of the silicon oxide layer is 48mN / m to 70mN / m.

5. The solar cell according to claim 1, characterized in that, The thickness of the silicon oxide layer is 20nm~50nm.

6. The solar cell according to claim 1, characterized in that, The silicon substrate has a light-receiving surface and a backlighting surface arranged opposite to each other, and the silicon oxide layer and the insulating adhesive layer are both stacked on the light-receiving surface of the silicon substrate.

7. The solar cell according to claim 1, characterized in that, The insulating adhesive layer includes a plurality of insulating adhesive strips, which are spaced apart along a first direction and extend along a second direction. The first direction and the second direction are arranged to intersect each other.

8. The solar cell according to claim 7, characterized in that, In the first direction, the insulating strip includes a protective portion and an extension portion, both of which cover the surface of the silicon oxide layer; The protective part is connected to the extension part on opposite sides in the first direction to form a continuous integral structure on the top surface; The distance from the highest point of the protective part to the surface of the silicon oxide layer is H1, and the distance from the highest point of the extended part to the surface of the silicon oxide layer is H2, wherein H1 > H2; The thickness of the insulating adhesive layer is equal to the distance from the highest point of the protective part to the surface of the silicon oxide layer.

9. The solar cell according to claim 8, characterized in that, The distance H1 from the highest point of the protective part to the surface of the silicon oxide layer is 3 μm to 6 μm; and / or, The distance H2 from the highest point of the extended portion to the surface of the silicon oxide layer is ≤1μm.

10. The solar cell according to claim 8, characterized in that, In the first direction, the total width of the insulating strip is W1, and the width of the protective part is W2, wherein: 0.5W1≤W2≤0.7W1.

11. The solar cell according to claim 8, characterized in that, The top surface of the protective part is a convex arc surface, and the top surface of the protective part and the top surface of the extension part are smoothly transitioned.

12. The solar cell according to claim 7, characterized in that, Along the second direction, the insulating strip includes a first insulating portion and a second insulating portion that are interconnected; The total width of the first isolation section in the first direction is W 11 The total width of the second isolation section in the first direction is W 12 Among them, W 12 >W 11 .

13. The solar cell according to claim 12, characterized in that, 1.2W 11 <W 12 ≤2.5W 11 ; In the formula, W 11 W is the total width of the first isolation section in the first direction. 12 The total width of the second isolation section in the first direction.

14. The solar cell according to claim 13, characterized in that, Both the first isolation section and the second isolation section include the protective section and the extension section; In the first direction, the total width W of the first isolation section 11 The width of the protective portion in the first isolation section is 0.45mm to 0.55mm, and the width of the protective portion is 0.25mm to 0.35mm. In the first direction, the total width W of the second isolation section 12 The width of the protective part in the second isolation section is 0.3mm to 0.7mm, and the width of the protective part is 0.55mm to 1mm.

15. The solar cell according to claim 12, characterized in that, Along the second direction, the surface of the silicon oxide layer includes an edge region and an intermediate region, the edge region being disposed on at least one side of the intermediate region in the second direction; The first isolation portion is stacked on the surface of the middle region, and the second isolation portion is stacked on the surface of the edge region.

16. A method for preparing a solar cell, characterized in that, The method for preparing the solar cell according to any one of claims 1-15 comprises the following steps: (1) Provide a silicon substrate; (2) A silicon oxide layer is deposited on the surface of the silicon substrate; (3) The surface of the silicon oxide layer is subjected to an oxygen-enriched treatment to ensure that the mass fraction of oxygen on the surface of the silicon oxide layer is ≥51.4 wt%; (4) An isolation adhesive layer is formed on the surface of the silicon oxide layer.

17. The method for preparing a solar cell according to claim 16, characterized in that, In step (3), the oxygen enrichment treatment of the surface of the silicon oxide layer includes one or more of the following methods: plasma activation, UV-O3 treatment, wet oxygen enrichment oxidation, ozone water oxidation, and dry oxygen oxidation.

18. The method for preparing a solar cell according to claim 17, characterized in that, In step (3), the surface of the silicon oxide layer is subjected to oxygen enrichment treatment by plasma activation. The plasma activation method has a radio frequency power of 100W~300W, a gas pressure of 0.5~1.5Torr, a frequency of 10MHz~15MHz, a processing time of 60s~120s, and a gas flow rate of 20sccm~100sccm.

19. The method for preparing a solar cell according to claim 17, characterized in that, In step (3), the surface of the silicon oxide layer is treated with oxygen enrichment by UV-O3 treatment. When the surface of the silicon oxide layer is subjected to oxygen-enriched treatment using the UV-O3 method, the wavelength of the ultraviolet light source is 254 nm and the intensity is 50 mW / cm². 2 ~100mW / cm 2 The processing time is 10 seconds to 2 minutes.

20. The method for preparing a solar cell according to claim 16, characterized in that, In step (4), the insulating adhesive layer is formed on the surface of the silicon oxide layer by inkjet printing or screen printing.

21. The method for preparing a solar cell according to claim 20, characterized in that, The release adhesive layer is formed on the surface of the silicon oxide layer using inkjet printing, including the following steps: (4.1) Apply a release adhesive to the surface of the silicon oxide layer in a predetermined area using a nozzle; (4.2) Curing the release adhesive to form a release adhesive layer.

22. The method for preparing a solar cell according to claim 21, characterized in that, In step (4.1), the distance between the bottom of the nozzle and the surface of the silicon oxide layer is 5mm to 10mm.

23. The method for preparing a solar cell according to claim 21, characterized in that, In step (4.2), the release aramid is cured by irradiation with an ultraviolet light source to form a release aramid layer; The ultraviolet light source has a wavelength of 365 nm, a curing time of 0.6~0.7 s, and an energy density of 3000 mJ / cm². 2 ~6000mJ / cm 2 The rated luminous intensity of the UV light source is 11000mW / cm². 2 .

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