TBC solar cell structure

Abstract

The utility model discloses a TBC solar cell structure, comprising a silicon substrate, the silicon substrate is divided into a front surface and a back surface, the front surface of the silicon substrate is provided with a passivation layer, one end surface of the passivation layer far away from the silicon substrate is covered with an antireflection layer, the back surface of the silicon substrate is provided with a first area and a second area, and the first area and the second area are arranged on the silicon substrate. The first regions and the second regions are alternately distributed on the back surface of the silicon substrate, a silicon nitride layer is arranged on each first region, a separation groove is formed between each first region and each second region, a first electrode and a second electrode are further arranged on the silicon substrate, a tunneling oxide layer is arranged on the silicon substrate, and the tunneling oxide layer is a SiO2 tunneling oxide layer. Compared with the prior art, the TBC solar cell structure provided by the utility model can perform separation protection on the connecting lines on the cell panel, thereby effectively reducing the probability of short circuit of the connecting lines of the TBC solar cell, effectively improving the yield of the TBC cell during production, and reducing the production cost.

Description

Technical Field

[0001] This utility model belongs to the field of X technology, specifically relating to a TBC solar cell structure. Background Technology

[0002] Passivated contact back-contact batteries, also known as TBC batteries, are batteries formed by combining TOPCon and IBC technologies. Due to their excellent passivation performance and back-contact design, they have high efficiency potential. The theoretical upper limit of TBC battery conversion efficiency is 29.56%, and they are poised to become a mainstream battery technology.

[0003] However, the current manufacturing process of TBC batteries involves complex processes and numerous steps. During production, short circuits in the battery panel's connection lines can easily occur, leading to poor contact and preventing current from flowing properly. Once current cannot flow normally, battery performance deteriorates, and even leakage occurs, seriously affecting battery safety. Therefore, the yield rate of TBC batteries is low, and production costs are high, making it difficult to meet market demand.

[0004] Therefore, in order to address the aforementioned technical problems, it is necessary to provide a TBC solar cell structure.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the overall background of this utility model and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Utility Model Content

[0006] The purpose of this invention is to provide a TBC solar cell structure that can isolate and protect the connection lines on the solar panel, thereby effectively reducing the probability of short circuits in the TBC solar cell connection lines, effectively improving the yield rate of TBC cells during production, and reducing production costs.

[0007] To achieve the above objectives, a specific embodiment of this utility model provides a TBC solar cell structure, including a silicon substrate. The silicon substrate is divided into a front side and a back side. A passivation layer is provided on the front side of the silicon substrate, and an anti-reflection layer is covered on the end face of the passivation layer away from the silicon substrate. The back side of the silicon substrate is provided with a first region and a second region, which are alternately distributed on the back side of the silicon substrate. A silicon nitride layer is provided on the first region, and a separation groove is formed between the first region and the second region. A first electrode and a second electrode are also provided on the silicon substrate. The separation groove can isolate and protect the connection lines on the solar panel, effectively reducing the probability of short circuits in the TBC solar cell connection lines.

[0008] In one or more embodiments of this utility model, a tunneling oxide layer is provided on the silicon substrate. The tunneling oxide layer is a SiO2 tunneling oxide layer. The SiO2 tunneling oxide layer helps electrons to be transported inside the battery, enabling electrons to effectively pass through through the tunneling effect, thus promoting electron transport and improving power generation efficiency to a certain extent.

[0009] In one or more embodiments of the present invention, a first silicon oxynitride layer is covered on one end face of the silicon nitride layer away from the first region, the first electrode is disposed on the first region, and the second electrode is disposed on the second region.

[0010] In one or more embodiments of this utility model, the thickness of the silicon nitride layer is 30-50 nm.

[0011] In one or more embodiments of this utility model, the width of the separation groove is 20 to 150 μm, and the depth of the separation groove is less than or equal to 50 μm.

[0012] In one or more embodiments of this utility model, the first region is a P region, the second region is an N region, and the ratio of the length of the P region to the length of the N region is 1:3.5.

[0013] In one or more embodiments of this utility model, the length of the P region is 700-1300 μm, and the length of the N region is 200-1050 μm.

[0014] In one or more embodiments of this utility model, the passivation layer is an aluminum oxide layer, and the thickness of the passivation layer is 5-10 nm.

[0015] In one or more embodiments of this utility model, the thickness of the antireflection layer, the first silicon oxynitride layer, and the second silicon oxynitride layer is 50-100 nm.

[0016] In one or more embodiments of the present invention, the thickness of the second silicon oxynitride layer is less than or equal to that of the first silicon oxynitride layer.

[0017] Compared with the prior art, the TBC solar cell structure of this utility model can isolate and protect the connection lines on the solar panel, thereby effectively reducing the probability of short circuits in the TBC solar cell connection lines, effectively improving the yield rate of TBC cells during production, and reducing production costs. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of a TBC solar cell structure according to one embodiment of the present invention;

[0020] Explanation of key figure labels:

[0021] 1. Silicon substrate; 11. Passivation layer; 12. Antireflective layer; 13. Tunneling oxide layer; 14. First region; 141. Silicon nitride layer; 142. First silicon oxynitride layer; 143. First electrode; 15. Second region; 151. Second silicon oxynitride layer; 152. Second electrode. Detailed Implementation

[0022] To enable those skilled in the art to better understand the technical solutions of this utility model, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this utility model.

[0023] like Figure 1 As shown, a TBC solar cell structure according to one embodiment of the present invention includes a silicon substrate 1, which is divided into a front side and a back side. A passivation layer 11 is provided on the front side of the silicon substrate 1, and an anti-reflection layer 12 is covered on the end face of the passivation layer 11 away from the silicon substrate 1. A first region 14 and a second region 15 are provided on the back side of the silicon substrate 1, and the first region 14 and the second region 15 are alternately distributed on the back side of the silicon substrate 1. A silicon nitride layer 141 is provided on the first region 14, and a separation groove is formed between the first region 14 and the second region 15. A first electrode 143 and a second electrode 152 are also provided on the silicon substrate 1.

[0024] Specifically, a silicon nitride layer 141 is fabricated using a mass production process to serve as an isolation and protective layer for the first region 14 and the second region 15. The silicon nitride layer 141 effectively isolates the first region 14 from the second region 15. Simultaneously, the separation groove creates a distance between the first region 14 and the second region 15, preventing short circuits in the TBC solar cell's connection lines and thus preventing leakage.

[0025] Preferably, the thickness of the silicon nitride layer 141 is 30–50 nm. The width of the separation trench is 20–150 μm, and the depth of the separation trench is less than or equal to 50 μm, matching the inward depth length of the silicon substrate 1. Specifically, the wet etching or laser etching processes used to prepare the silicon nitride layer 141 are existing technologies, requiring no additional equipment on the existing production line and thus avoiding additional production costs. Furthermore, the separation trench within the aforementioned numerical range allows for laser patterning and trenching in approximately 5 seconds, significantly improving trenching efficiency.

[0026] A tunneling oxide layer 13 is formed on the silicon substrate 1. The tunneling oxide layer 13 is a SiO2 tunneling oxide layer. When depositing the SiO2 tunneling oxide layer on the TBC solar cell, the thickness of the SiO2 tunneling oxide layer is adjusted to 0.5–2.5 nm by adjusting the nitrogen doping amount. The process gases are SiH4, N2, and N2O. The gas flow ratio is N2O:SiH4:N2 = 1–3:1:30–40.

[0027] Specifically, the SiO2 tunneling oxide layer helps electrons transport inside the battery through the tunneling effect, enabling electrons to effectively pass through the SiO2 tunneling oxide layer, thereby promoting electron transport and improving power generation efficiency to a certain extent.

[0028] Furthermore, since both the first silicon oxynitride layer 142 and the second silicon oxynitride layer 151 are on the back side of the TBC solar cell, there are no grid lines on the front side of the TBC solar cell, which enhances the illumination area and further increases the surface illumination area of ​​the TBC solar cell, thereby increasing the power generation efficiency of the TBC solar cell.

[0029] like Figure 1 As shown, the first region 14 is a P-region, and the second region 15 is an N-region, with a length ratio of 1:3.5 between the P-region and the N-region. A first silicon oxynitride layer 142 covers the end face of the silicon nitride layer 141 away from the first region 14. A first electrode 143 is disposed on the first region 14, and a second electrode 152 is disposed on the second region 15. The second region 15 is also provided with a second silicon oxynitride layer 151 that matches the first silicon oxynitride layer 142.

[0030] Specifically, an intrinsic amorphous silicon layer with a thickness of 20-300 nm is first prepared on the back side of the silicon substrate 1, and then the amorphous silicon layer is crystallized by laser to obtain a first silicon oxynitride layer 142 and a second silicon oxynitride layer 151.

[0031] During crystallization, the laser power density is 5KW / cm² to 30KW / cm², the laser irradiation time is 5ms to 200ms, and the laser wavelength is 300 to 600nm. Laser crystallization is performed twice. The first time, the power density is no higher than 15KW / cm², and the laser irradiation time is 30ms to 150ms. The second time, the power density is no lower than 15KW / cm², and the laser irradiation time is 5ms to 50ms. The first electrode 143 and the second electrode 152 are respectively disposed in the regions of the first silicon oxynitride layer 142 and the second silicon oxynitride layer 151 after the second crystallization.

[0032] Specifically, the first silicon oxynitride layer 142 and the second silicon oxynitride layer 151 can form a thin protective layer on the surface of the solar cell, thereby protecting the cell from external damage and corrosion. At the same time, the first silicon oxynitride layer 142 and the second silicon oxynitride layer 151 can also increase the stability and lifespan of the solar cell, improving its reliability and durability.

[0033] Preferably, the length of the P-region is 700–1300 μm, and the length of the N-region is 200–1050 μm. The thickness of the second silicon oxynitride layer 151 is less than or equal to the thickness of the first silicon oxynitride layer 142. The thicknesses of the antireflective layer 12, the first silicon oxynitride layer 142, and the second silicon oxynitride layer 151 are all 50–100 nm.

[0034] Specifically, the thicknesses of the antireflection layer 12, the first silicon oxynitride layer 142, and the second silicon oxynitride layer 151 decrease sequentially from the inner side of the silicon substrate outwards. When light shines on the silicon substrate 1, reflection and refraction occur at the antireflection layer 12, the first silicon oxynitride layer 142, and the second silicon oxynitride layer 151. By depositing the antireflection layer 12 on the surface of the silicon substrate 1, the reflection and transmission of light can be controlled, causing reflected light to interfere with and cancel each other out, thereby reducing reflected light and allowing more light energy to reach the surface of the TBC solar cell, thus improving the power and efficiency of the photovoltaic module.

[0035] In addition, the first electrode 143 and the second electrode 152 are respectively screen-printed on the first region 14 and the second region 15 on the back side of the silicon substrate 1 to form metal contacts, and then sintered at a temperature of 680 to 880°C to form Ag-Si ohmic contacts to form electrodes.

[0036] It is worth noting that in order to repair the damage caused by laser crystallization to the TBC solar cell, the TBC solar cell needs to be annealed and oxidized. This not only reduces the surface concentration in the non-laser region, but also increases the junction depth, while avoiding the etching of the doped layers in the first region 14 and the second region 15.

[0037] Preferably, the oxidation treatment temperature is 650℃~800℃.

[0038] To reduce surface defects, improve photoelectric conversion efficiency, and extend lifespan of TBC solar cells, ALD technology is preferentially used to prepare the passivation layer 11. The passivation layer 11 is an aluminum oxide layer with a thickness of 5–10 nm. Specifically, the passivation layer 11 can reduce the surface recombination rate, improve cell lifespan, reduce open-circuit voltage, and effectively prevent direct contact between the first electrode 143, the second electrode 152, and the silicon wafer, avoiding metal-induced surface recombination, reducing charge recombination loss, and thus improving photoelectric conversion efficiency.

[0039] Compared with the prior art, the TBC solar cell structure of this utility model can isolate and protect the connection lines on the solar panel, thereby effectively reducing the probability of short circuits in the TBC solar cell connection lines, effectively improving the yield rate of TBC cells during production, and reducing production costs.

[0040] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0041] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A TBC solar cell structure, comprising a silicon substrate, said silicon substrate being divided into a front side and a back side, characterized in that, The silicon substrate has a passivation layer on its front side, and an anti-reflection layer is covered on the end of the passivation layer away from the silicon substrate. The silicon substrate has a first region and a second region on its back side, which are alternately distributed on the back side of the silicon substrate. The first region has a silicon nitride layer, and a separation groove is formed between the first region and the second region. The silicon substrate also has a first electrode and a second electrode.

2. The TBC solar cell structure according to claim 1, characterized in that, The silicon substrate has a tunneling oxide layer, which is a SiO2 tunneling oxide layer.

3. The TBC solar cell structure according to claim 1, characterized in that, The silicon nitride layer is covered with a first silicon oxynitride layer on one end face away from the first region, the first electrode is disposed on the first region, and the second electrode is disposed on the second region.

4. The TBC solar cell structure according to claim 1, characterized in that, The thickness of the silicon nitride layer is 30–50 nm.

5. A TBC solar cell structure according to claim 1, characterized in that, The separation tank has a width of 20–150 μm and a depth of less than or equal to 50 μm.

6. A TBC solar cell structure according to any one of claims 1 to 5, characterized in that, The first region is region P, and the second region is region N. The ratio of the length of region P to the length of region N is 1:3.

5.

7. A TBC solar cell structure according to claim 6, characterized in that, The length of the P region is 700–1300 μm, and the length of the N region is 200–1050 μm.

8. A TBC solar cell structure according to claim 1, characterized in that, The passivation layer is an aluminum oxide layer, and the thickness of the passivation layer is 5-10 nm.

9. A TBC solar cell structure according to claim 1, characterized in that, The thickness of the antireflective layer, the first silicon oxynitride layer, and the second silicon oxynitride layer is 50–100 nm.

10. A TBC solar cell structure according to claim 9, characterized in that, The thickness of the second silicon oxynitride layer is less than or equal to that of the first silicon oxynitride layer.

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