Back contact type solar cell and solar cell module

Abstract

The utility model relates to the technical field of solar cells, and discloses a back contact type solar cell and a solar cell module, the back contact type solar cell comprises an N-type doped polycrystalline silicon layer and a P-type doped polycrystalline silicon layer which are arranged on a tunneling layer, and the N-type doped polycrystalline silicon layer and the P-type doped polycrystalline silicon layer are insulated and isolated through an isolation region; the first interface passivation layer covers the N-type doped polycrystalline silicon layer, the P-type doped polycrystalline silicon layer and the isolation region; the first surface passivation layer is arranged on the first interface passivation layer; the first antireflection layer is arranged on the first surface passivation layer; the first electrode and the second electrode are arranged on the back face of the substrate, the first electrode penetrates through the interface passivation layer to be in contact with the N-type doped polycrystalline silicon layer, and the second electrode penetrates through the interface passivation layer to be in contact with the P-type doped polycrystalline silicon layer. According to the utility model, the sintering temperature is effectively reduced, the sintering time is shortened, the cost is reduced, the possibility of membrane explosion on the back surface is reduced, and the efficiency attenuation is slowed down.

Description

Technical Field

[0001] The utility model relates to the technical field of solar cells, in particular to a back-contact solar cell and a solar cell module. Background Art

[0002] The back-contact solar cell is a new type of solar cell technology, in which both the positive electrode and the negative electrode are arranged on the back surface, and the wires on the battery chip are connected on the back surface. The main grid is not arranged on the front surface, so that light can irradiate the battery chip more fully, reducing the light shielding of the front main grid and the electrode, improving the efficiency and stability of the battery, and also showing higher battery efficiency, thus having a wide application prospect.

[0003] At the present stage, the conventional structure of the back-contact solar cell is as follows: on the front surface of the substrate, a passivation layer and an antireflection layer are sequentially arranged on the front surface of the substrate surface. The back surface of the substrate includes a tunneling layer on the back surface of the substrate, a P-type polysilicon doping layer on the tunneling layer, an N-type polysilicon doping layer, a passivation layer on the P-type polysilicon doping layer and the N-type polysilicon doping layer, and an antireflection layer on the passivation layer. A positive electrode is arranged on the P-type polysilicon doping layer, and a negative electrode is arranged on the N-type polysilicon doping layer. The performance and life of the battery are improved through hydrogen passivation and interface passivation. The conventional hydrogen passivation effect and interface passivation effect are realized through sintering treatment. To achieve a good passivation effect, a higher sintering temperature and a longer sintering time are required, increasing the cost and reducing the yield. Summary of the Utility Model

[0004] The technical problem to be solved by the utility model is to provide a back-contact solar cell and a solar cell module, which can reduce the sintering temperature during passivation sintering, shorten the sintering time, reduce the cost, and slow down the efficiency decay, and reduce the possibility of film explosion on the back surface.

[0005] To solve the above technical problem, the first aspect of the utility model provides a back-contact solar cell, including:

[0006] A substrate,

[0007] A first tunneling layer and a second tunneling layer arranged on the back surface of the substrate;

[0008] An N-type doped polysilicon layer arranged on the first tunneling layer and a P-type doped polysilicon layer arranged on the second tunneling layer, and the N-type doped polysilicon layer and the P-type doped polysilicon layer are insulated and isolated by an isolation region;

[0009] A first interface passivation layer covering the N-type doped polysilicon layer, the P-type doped polysilicon layer and the isolation region;

[0010] The first surface passivation layer disposed on the first interface passivation layer;

[0011] The first antireflection layer disposed on the first surface passivation layer;

[0012] The first electrode and the second electrode disposed on the back surface of the substrate, the first electrode penetrates the interface passivation layer and contacts the N-type doped polysilicon layer, and the second electrode penetrates the interface passivation layer and contacts the P-type doped polysilicon layer.

[0013] As an improvement of the above solution, the density of the first interface passivation layer is less than that of the first surface passivation layer.

[0014] As an improvement of the above solution, the density of the first interface passivation layer is less than that of the first tunneling layer and the second tunneling layer.

[0015] As an improvement of the above solution, the first interface passivation layer is a porous oxide film layer formed by low-temperature oxidation of the substrate, or a porous oxide film layer formed by deposition on the substrate;

[0016] The porous oxide film layer is an oxide film layer with a pore structure, and the hole density of the first interface passivation layer is less than that of the first surface passivation layer.

[0017] As an improvement of the above solution, the hole density of the first interface passivation layer is less than that of the first tunneling layer and the second tunneling layer.

[0018] As an improvement of the above solution, the thickness of the first interface passivation layer is 0.5 nm to 20 nm.

[0019] As an improvement of the above solution, the first interface passivation layer is one or a combination of two of a silicon oxide film layer and a silicon oxynitride film layer.

[0020] As an improvement of the above solution, the back surface of the substrate has a pyramid texture structure.

[0021] As an improvement of the above solution, both the first tunneling layer and the second tunneling layer are silicon oxide layers, the thickness of the first tunneling layer is 1 nm to 5 nm; the thickness of the second tunneling layer is 1 nm to 5 nm;

[0022] The thickness of the N-type doped polysilicon layer is 50 nm to 350 nm; the thickness of the P-type doped polysilicon layer is 50 nm to 350 nm;

[0023] The first surface passivation layer is an aluminum oxide film layer; the thickness of the first surface passivation layer is 60 nm to 150 nm;

[0024] The first anti-reflection layer is a silicon nitride film layer; the thickness of the first anti-reflection layer is 80 nm to 150 nm.

[0025] As an improvement to the above solution, the front surface of the substrate is provided with: a second interface passivation layer on the front surface of the substrate, and the density of the second interface passivation layer is less than that of the second surface passivation layer;

[0026] a second surface passivation layer on the second interface passivation layer;

[0027] a second anti-reflection layer on the second surface passivation layer.

[0028] As an improvement to the above solution, the second interface passivation layer is a porous oxide film layer formed by low-temperature oxidation of the substrate or a porous oxide film layer deposited on the substrate;

[0029] The porous oxide film layer is an oxide film layer with a pore structure;

[0030] The thickness of the second interface passivation layer is 0.5 nm to 20 nm.

[0031] The second aspect of the present invention also provides a solar cell module, which includes the back-contact solar cell described above.

[0032] Implementing the present invention has the following beneficial effects:

[0033] (1) It improves the passivation performance of the back surface of the back-contact solar cell before sintering, effectively reduces the sintering temperature, shortens the sintering time, and thus reduces the cost;

[0034] (2) H in the first anti-reflection layer will overflow during high-temperature sintering, which will cause film bursting on the back surface of the back-contact solar cell. By setting the first interface passivation layer to reduce the sintering temperature, the probability of film bursting can be reduced; at the same time, it can prevent H in the N-type doped polysilicon layer and the P-type doped polysilicon layer from diffusing into the first anti-reflection layer, thereby reducing the overflow of H and further reducing the possibility of film bursting;

[0035] (3) The setting of the first interface passivation layer also slows down the efficiency decay of the back-contact solar cell during static storage, can also increase the weather resistance of the back-contact solar cell, reduce its efficiency decay during ultraviolet irradiation, and thus extend its service life. Description of the Drawings

[0036] Figure 1 : Schematic diagram of the back surface structure of a back-contact solar cell in the present invention;

[0037] Figure 2: Schematic structural diagram of a back-contact solar cell in the present utility model;

[0038] Figure 3 : Schematic structural diagram of another back-contact solar cell in the present utility model;

[0039] Reference numerals:

[0040] 1 - Substrate; 2 - First tunneling layer; 3 - Second tunneling layer; 4 - N-type doped polysilicon layer; 5 - P-type doped polysilicon layer; 6 - Isolation region; 7 - First interface passivation layer; 8 - First surface passivation layer; 9 - First antireflection layer; 10 - First electrode; 11 - Second electrode; 12 - Second surface passivation layer; 13 - Second antireflection layer; 14 - First interface passivation layer. Specific embodiments

[0041] To make the objectives, technical solutions, and advantages of the present utility model clearer, the present utility model will be further described in detail below with specific embodiments.

[0042] To solve the above problems, a first aspect of the present utility model provides a back-contact solar cell, as Figure 1 shown, including:

[0043] Substrate 1,

[0044] The first tunneling layer 2 and the second tunneling layer 3 provided on the back surface of the substrate 1;

[0045] The N-type doped polysilicon layer 4 provided on the first tunneling layer 2 and the P-type doped polysilicon layer 5 provided on the second tunneling layer 3, and the N-type doped polysilicon layer 4 and the P-type doped polysilicon layer 5 are insulated and isolated by the isolation region 6;

[0046] The first interface passivation layer 7 covering the N-type doped polysilicon layer 4, the P-type doped polysilicon layer 5, and the isolation region 6;

[0047] The first surface passivation layer 8 provided on the first interface passivation layer 7;

[0048] The first antireflection layer 9 provided on the first surface passivation layer 8;

[0049] The first electrode 10 and the second electrode 11 provided on the back surface of the substrate 1, the first electrode 10 penetrates through the first interface passivation layer 7 and contacts the N-type doped polysilicon layer 4, and the second electrode 11 penetrates through the first interface passivation layer 7 and contacts the P-type doped polysilicon layer 5.

[0050] Preferably, a second surface passivation layer 12 and a second antireflection layer 13 are provided on the front surface of the substrate 1, and the structure of the formed back-contact solar cell is asFigure 2 as shown

[0051] In the present utility model, a first interface passivation layer 7 is provided on the N-type doped polysilicon layer 4, the P-type doped polysilicon layer 5 and the isolation region 6, which improves the passivation performance of the back surface of the back-contact solar cell before sintering, effectively reduces the sintering temperature, shortens the sintering time, and thus reduces the cost.

[0052] Meanwhile, H (hydrogen) in the first antireflection layer 9 will overflow during high-temperature sintering, which will cause film bursting on the back surface of the back-contact solar cell. However, by setting the first interface passivation layer 7 to reduce the sintering temperature, the probability of film bursting can be reduced. On the other hand, the N-type doped polysilicon layer 4 and the P-type doped polysilicon layer 5 contain relatively more H, and H is not easy to pass through the first tunneling layer 2, the second tunneling layer 3 and the first interface passivation layer 7. Therefore, setting the first interface passivation layer 7 can prevent H in the N-type doped polysilicon layer 4 and the P-type doped polysilicon layer 5 from diffusing to the first antireflection layer 9, thereby reducing the overflow of H and further reducing the possibility of film bursting. If the first interface passivation layer 7 is not provided, the path for H in the N-type doped polysilicon layer 4 and the P-type doped polysilicon layer 5 to enter the first antireflection layer 9 becomes shorter, thereby increasing the possibility of film bursting.

[0053] In addition, the setting of the first interface passivation layer 7 also slows down the efficiency decay of the back-contact solar cell during static storage, can also increase the weather resistance of the back-contact solar cell, reduce its efficiency decay during ultraviolet irradiation, and thus extend its service life.

[0054] Preferably, the back surface of the substrate 1 has a pyramid texture structure, which is prepared by the texturing process in the art. The texture structure can scatter the incident light, reduce the specular reflection of light, thereby increasing the residence time of light on the back surface of the cell, and thus improving the light utilization rate and the photoelectric conversion efficiency.

[0055] Furthermore, the tunneling layer includes a first tunneling layer 2 and a second tunneling layer 3. The first tunneling layer 2 is a silicon oxide layer, and the thickness of the first tunneling layer 2 is 1 nm to 5 nm; the second tunneling layer 3 is a silicon oxide layer, and the thickness of the second tunneling layer 3 is 1 nm to 5 nm; the thicknesses of the first tunneling layer 2 and the second tunneling layer 3 can be different, and the conductivities of the first tunneling layer 2 and the second tunneling layer 3 can also be different.

[0056] Preferably, the first interface passivation layer 7 covers the N-type doped polysilicon layer 4, P-type doped polysilicon layer 5, and isolation region 6. An N-type doped polysilicon layer 4 is disposed on the first tunneling layer 2, and the doping elements include, but are not limited to, P (phosphorus) and As (arsenic). The thickness of the N-type doped polysilicon layer 4 is 50 nm to 350 nm. A P-type doped polysilicon layer 5 is disposed on the second tunneling layer 3, and the doping elements include, but are not limited to, B (boron), Al (aluminum), and Ga (gallium). The thickness of the P-type doped polysilicon layer 5 is 50 nm to 350 nm.

[0057] Preferably, the density of the first interface passivation layer 7 is less than that of the first surface passivation layer 8, and the density of the first interface passivation layer 7 is less than that of the first tunneling layer 2 and the second tunneling layer 3, so that the formed first interface passivation layer 7 is a porous oxide film layer. Exemplarily, the porous oxide film layer is an oxide film layer with a pore structure. The first interface passivation layer 7 has a large hole density, while the first tunneling layer 2, the second tunneling layer 3, and the first surface passivation layer 8 have a small hole density. This can not only play a role in interface passivation, but also facilitate the diffusion of H in the first surface passivation layer 8 and the first antireflection layer 9 to the substrate 1 through the first interface passivation layer 7, make up for the deficiency of surface passivation by H during the sintering process, reduce the influence of dangling bonds on the efficiency of the solar cell, and further reduce the sintering temperature and sintering time.

[0058] Furthermore, the thickness of the first interface passivation layer 7 is 0.5 nm to 20 nm. The first interface passivation layer 7 is relatively thin. While not affecting its interface passivation effect, the sunlight entering from the front of the cell can also be reflected at the first interface passivation layer 7, thereby improving the photoelectric conversion efficiency of the back contact solar cell. Moreover, the diffusion path of H to the substrate 1 is shortened, and a better hydrogen passivation effect can be exhibited. If the thickness of the first interface passivation layer 7 is less than 0.5 nm, the interface passivation effect is weak. If the thickness of the first interface passivation layer 7 is greater than 20 nm, it will not only cause the film layer on the back of the back contact solar cell to be whitish in color and the reflectivity to increase, but also increase the diffusion difficulty of H and reduce the passivation effect.

[0059] Optionally, the first interface passivation layer 7 is a porous oxide film layer formed by low-temperature oxidation of the substrate 1, and the first interface passivation layer 7 is one or a combination of two of a silicon oxide film layer and a silicon oxynitride film layer. The low-temperature oxidation method can be oxidation by introducing O3 during the drying process of the texturing on the back of the substrate 1, or thermal oxidation by introducing O2, or oxidation with concentrated nitric acid on the back pyramid texture structure, or wet oxidation, or other low-temperature oxidation methods in the art. The low-temperature oxidation method of the first interface passivation layer 7 in the present invention is not specifically limited.

[0060] In some other embodiments, the first interface passivation layer 7 is a porous oxide film layer formed by deposition on the substrate 1. For example, by using a conventional PECVD (Plasma Enhanced Chemical Vapor Deposition) setup to introduce the required Si source and O source, or Si source, O source, and N source, and controlling the growth conditions, a porous silicon oxide film layer or silicon oxynitride film layer can be formed.

[0061] Preferably, the first surface passivation layer 8 is an alumina film layer; the thickness of the first surface passivation layer 8 is 60 nm to 150 nm; the first antireflection layer 9 is a silicon nitride film layer; the thickness of the first antireflection layer 9 is 80 nm to 150 nm. At this time, the first interface passivation layer 7, the first surface passivation layer 8, and the first antireflection layer 9 are sequentially provided on the N-type doped polysilicon layer 4, and the first interface passivation layer 7, the first surface passivation layer 8, and the first antireflection layer 9 are also sequentially provided on the P-type doped polysilicon layer 5. The conductive performance of the porous first interface passivation layer 7 can be avoided, and the N-type doped polysilicon layer 4 and the P-type doped polysilicon layer 5 can be well insulated and isolated completely.

[0062] Furthermore, the first surface passivation layer 8 and the first antireflection layer 9 are sequentially provided on the first interface passivation layer 7, making the isolation region 6 a three-layer structure with the first base passivation layer, the first surface passivation layer 8, and the first antireflection layer 9. This can further improve the sintering window, keep the efficiency retention rate of the back-contact solar cell high, and reduce the efficiency decay.

[0063] Preferably, the second surface passivation layer 12 is an alumina film layer; the thickness of the second surface passivation layer 12 is 1 nm to 10 nm. The second antireflection layer 13 is a silicon nitride film layer, and the thickness of the second antireflection layer 13 is 20 nm to 150 nm.

[0064] In some preferred embodiments, the front surface of the substrate 1 is provided with: a second interface passivation layer 14 located on the front surface of the substrate 1;

[0065] a second surface passivation layer 12 located on the second interface passivation layer 14;

[0066] a second antireflection layer 13 located on the second surface passivation layer 12.

[0067] The structure of the formed back-contact solar cell is as Figure 3 shown.

[0068] In the present utility model, the positive surface structure of the back-contact solar cell is further improved. A second interface passivation layer 14 is provided on the positive surface of the substrate 1, which can not only further reduce the sintering temperature and shorten the sintering time, but also slow down the efficiency decay of the back-contact solar cell during static storage, increase the weather resistance of the back-contact solar cell, reduce its efficiency decay under ultraviolet irradiation, and thus extend its service life.

[0069] Furthermore, the positive surface of the substrate 1 has a pyramid texture structure.

[0070] Furthermore, the density of the second interface passivation layer 14 is less than that of the second surface passivation layer 12; the formed first interface passivation layer 7 is a porous oxide film layer, and the second interface passivation layer 14 has a thickness of 0.5 nm to 20 nm, which can further improve the photoelectric conversion efficiency of the back-contact solar cell and achieve better hydrogen passivation and interface passivation effects at a lower sintering temperature and a shorter sintering time. The refractive index and thickness of the second interface passivation layer 14 can be the same as or different from those of the first interface passivation layer 7, and the specific values can be reasonably adjusted according to the actual situation.

[0071] Furthermore, the second interface passivation layer 14 is a porous oxide film layer formed by low-temperature oxidation of the substrate 1 or a porous oxide film layer deposited on the substrate 1; its specific preparation process is the same as that of the first interface passivation layer 7.

[0072] Correspondingly, the present utility model also provides a solar cell module, which includes the back-contact solar cell described above.

[0073] The above-disclosed is only a preferred embodiment of the present utility model. Of course, it cannot be used to limit the scope of the rights of the present utility model. Therefore, equivalent changes made according to the claims of the present utility model still fall within the scope covered by the present utility model.

Claims

1. A back-contact solar cell, characterized in that, Comprising: A substrate, A first tunneling layer and a second tunneling layer disposed on the back surface of the substrate; An N-type doped polysilicon layer disposed on the first tunneling layer and a P-type doped polysilicon layer disposed on the second tunneling layer, and the N-type doped polysilicon layer and the P-type doped polysilicon layer are insulated from each other by an isolation region; A first interface passivation layer covering the N-type doped polysilicon layer, the P-type doped polysilicon layer and the isolation region; A first surface passivation layer disposed on the first interface passivation layer; A first antireflection layer disposed on the first surface passivation layer; A first electrode and a second electrode disposed on the back surface of the substrate, the first electrode penetrates the interface passivation layer and contacts the N-type doped polysilicon layer, and the second electrode penetrates the interface passivation layer and contacts the P-type doped polysilicon layer.

2. The back-contact solar cell according to claim 1, wherein The density of the first interface passivation layer is less than the density of the first surface passivation layer.

3. The back-contact solar cell according to claim 1, characterized in that, The density of the first interface passivation layer is less than the density of the first tunneling layer and the second tunneling layer.

4. The back contact solar cell according to claim 2 or 3, characterized in that, The first interface passivation layer is a porous oxide film layer formed by low-temperature oxidation of the substrate or a porous oxide film layer deposited on the substrate; The porous oxide film layer is an oxide film layer having a pore structure; The hole density of the first interface passivation layer is less than the hole density of the first surface passivation layer.

5. The back contact solar cell according to claim 4, wherein, The hole density of the first interface passivation layer is less than the hole density of the first tunneling layer and the second tunneling layer.

6. The back-contact solar cell according to claim 2 or 3, characterized in that, The thickness of the first interface passivation layer is 0.5 nm to 20 nm.

7. The back-contact solar cell according to claim 2, characterized in that, The first interface passivation layer is one or a combination of two of a silicon oxide film layer and a silicon oxynitride film layer.

8. The back contact solar cell according to claim 1, wherein The back surface of the substrate has a pyramid texture structure.

9. The back-contact solar cell according to claim 1, wherein Both the first tunneling layer and the second tunneling layer are silicon oxide layers, the thickness of the first tunneling layer is 1 nm to 5 nm; the thickness of the second tunneling layer is 1 nm to 5 nm; The thickness of the N-type doped polysilicon layer is 50 nm to 350 nm; the thickness of the P-type doped polysilicon layer is 50 nm to 350 nm; The first surface passivation layer is an aluminum oxide film layer; the thickness of the first surface passivation layer is 60 nm to 150 nm; The first antireflection layer is a silicon nitride film layer; the thickness of the first antireflection layer is 80 nm to 150 nm.

10. The back-contact solar cell according to claim 1, characterized in that, On the front surface of the substrate are provided: a second interface passivation layer located on the front surface of the substrate; A second surface passivation layer located on the second interface passivation layer, and the density of the second interface passivation layer is less than the density of the second surface passivation layer; A second antireflection layer located on the second surface passivation layer.

11. The back-contact solar cell according to claim 10, wherein, The second interface passivation layer is a porous oxide film layer formed by low-temperature oxidation of the substrate or a porous oxide film layer deposited on the substrate; The porous oxide film layer is an oxide film layer having a pore structure; The thickness of the second interface passivation layer is 0.5 nm to 20 nm.

12. A solar cell module, characterized in that, It includes the back-contact solar cell according to any one of claims 1 to 9.

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