Solar cell

Abstract

The utility model discloses a solar cell, which is applied to the field of photovoltaic technology and comprises a substrate; an emitter is arranged on the surface of the substrate; a step surface is formed on the side surface of the substrate; the side surface of the step surface at least comprises the side surface of the emitter; the ratio of the height H of the side surface of the step surface to the sum of the thicknesses of the emitter and the substrate is 1: 1.5-1: 300, and the ratio comprises values at two ends; a first passivation layer is arranged on the surface, deviating from the substrate, of the emitter; the first passivation layer extends to the step surface; a surface of the first passivation layer covering a side surface of the emitter and a side surface of the substrate not covered by the first passivation layer are provided with a second passivation layer. According to the utility model, the first passivation layer is arranged on the surface of the emitting electrode and extends to cover the side surface of the emitting electrode, and then the second passivation layer is arranged on the side surface of the substrate and covers the first passivation layer on the side surface of the substrate and the side surface of the emitting electrode at the same time, so that the passivation effect can be enhanced, and the cost can be reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to photovoltaic technology field especially relates to a solar cell. BACKGROUND

[0002] The ASP technology (Advanced Surface Passivation Technology) first adopts laser to slice the whole cell piece, thereby forming a cutting surface on the side surface of the cell piece, and then adopts a passivation film to passivate the cutting surface. Since the ASP technology has a good effect on repairing microscopic damage and can reduce passivation loss, the conversion efficiency of the cell and the module is improved, and the power of the TOPCon (Tunnel Oxide Passivating Contact) 72 double-glass module can be increased by 4W+. The passivation of the cutting surface is mainly to repair and protect the cutting damage of the emitter (PN junction), and the mainstream thickness of the side passivation layer is 50nm-100nm, which has a high cost. SUMMARY

[0003] Therefore, the utility model discloses a solar cell for enhancing passivation effect and reducing cost.

[0004] To solve the above technical problems, the utility model provides a solar cell, which comprises a substrate, an emitter arranged on the surface of the substrate, a step surface formed on the side surface of the substrate, a side surface of the step surface comprising at least a side surface of the emitter, a ratio of the height H of the side surface of the step surface to the sum of the thickness of the emitter and the substrate being 1:1.5-1:300, and the ratio including both ends.

[0005] The emitter is provided with a first passivation layer on the surface away from the substrate, and the first passivation layer extends to the step surface.

[0006] The surface of the first passivation layer covering the side surface of the emitter and the side surface of the substrate not covered by the first passivation layer are provided with a second passivation layer.

[0007] Optionally, the thickness of the second passivation layer is 5nm-50nm, and the thickness includes both ends.

[0008] Optionally, the thickness of the first passivation layer is less than 10nm, and / or

[0009] The width of the emitter is less than the width of the substrate, and / or

[0010] The first passivation layer extends to the bottom surface of the step surface.

[0011] Optionally, the height H of the side surface of the step surface is greater than the thickness of the emitter.

[0012] Optionally, the height H of the side surface of the step surface is 0.5 μm to 100 μm, and the values at both ends are included.

[0013] Optionally, the width D of the bottom surface of the step surface is 0.05 μm to 50 μm, and the values at both ends are included.

[0014] Optionally, the thickness of the emitter is 1 μm to 2 μm, and the values at both ends are included.

[0015] Optionally, one end of the second passivation layer extends to the surface of the first passivation layer away from the emitter, and covers part of the surface of the first passivation layer away from the emitter; the other end of the second passivation layer extends to the surface of the substrate away from the emitter, and covers part of the surface of the substrate away from the emitter.

[0016] Optionally, the first passivation layer comprises an ALO x layer.

[0017] Optionally, the second passivation layer comprises at least one of an ALO x layer, a silicon nitride layer, a silicon oxynitride layer, an aluminum nitride layer, and an aluminum oxynitride layer.

[0018] Optionally, the surface of the first passivation layer away from the emitter is provided with an anti-reflection layer.

[0019] Optionally, the anti-reflection layer comprises at least one of a silicon nitride layer and a silicon oxynitride layer.

[0020] Optionally, the thickness of the anti-reflection layer is 80 nm to 90 nm, and the values at both ends are included.

[0021] Optionally, the anti-reflection layer is sandwiched between the first passivation layer and the second passivation layer.

[0022] Optionally, the side surface of the step surface comprises the side surface of the emitter and the side surface of part of the substrate. It can be seen that the solar cell provided by the utility model comprises: a substrate; the surface of the substrate is provided with an emitter; a step surface is formed on the side surface of the substrate; the side surface of the step surface at least comprises the side surface of the emitter; the ratio of the height H of the side surface of the step surface to the sum of the thickness of the emitter and the substrate is 1:1.5~1:300, and the ratio comprises both ends; the surface of the first passivation layer covering the side surface of the emitter and the side surface of the substrate not covered by the first passivation layer is provided with a second passivation layer. The height of the side surface of the step surface and the sum of the thickness of the emitter and the substrate have a suitable ratio to ensure the coverage of the passivation layer, the first passivation layer is arranged on the surface of the emitter, the first passivation layer extends to cover the side surface of the emitter, and the second passivation layer is arranged on the side surface of the substrate, so that the second passivation layer covers the first passivation layer on the side surface of the emitter and the side surface of the substrate at the same time, thereby forming a multilayer passivation layer on the side surface of the emitter, the side surface of the emitter is protected, and since the first passivation layer has been arranged on the side surface of the emitter, the second passivation layer does not need to be thick, so that the passivation effect can be enhanced and the cost can be reduced. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the utility model or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or the prior art description. Obviously, the drawings in the following description are only the embodiments of the utility model, and for those skilled in the art, other drawings can also be obtained without creative labor based on the provided drawings.

[0024] Figure 1 The structure schematic diagram of the solar cell provided by the utility model embodiment is shown in the figure.

[0025] Figures 2 to 4 The preparation flow schematic diagram of the solar cell provided by the utility model embodiment is shown in the figure.

[0026] The following explains the signs in the drawings:

[0027] 1-substrate;2-emitter;3-initial groove;4-first passivation layer;5-cutting groove;6-second passivation layer. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be clearly and completely described in the following with reference to the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by the ordinary skilled in the art without creative labor belong to the scope of protection of the utility model.

[0029] Please refer to Figure 1 , Figure 1 A structure schematic diagram of a solar cell is provided in the embodiments of the utility model. The solar cell can include: a substrate 1; an emitter 2 is arranged on the surface of the substrate 1; a step surface is formed on the side of the substrate 1; the side of the step surface at least includes the side of the emitter 2; the ratio of the height H of the side of the step surface to the sum of the thicknesses of the emitter 2 and the substrate 1 is 1:1.5~1:300, and the ratio includes the values at both ends;

[0030] The surface of the first passivation layer 4 covering the side of the emitter 2 and the side of the substrate 1 not covered by the first passivation layer 4 is provided with a second passivation layer 6.

[0031] The surface of the first passivation layer 4 covering the side of the emitter 2 and the side of the substrate 1 not covered by the first passivation layer 4 is provided with a second passivation layer 6.

[0032] It should be noted that the ratio of the height H of the side of the step surface to the sum of the thicknesses of the emitter 2 and the substrate 1 in the embodiments adopts the above range, which can ensure that the height H of the side of the step surface is not less than the thickness of the emitter 2, so that when the first passivation layer 4 extends to the bottom surface of the step surface, the side of the emitter 2 can be completely covered. In addition, it should be noted that the height direction of the step surface in the embodiments is parallel to the direction of the cutting surface. However, since the step surface is formed by etching, the etching rates of different substances will be different in the etching process, which will cause differences in the etching morphology of different parts and different substances, and the step surface may be irregular due to the process. Preferably, the height H of the side of the step surface in the embodiments is the average value of the distances from each position on the bottom surface of the step surface to the side surface of the emitter 2 away from the substrate 1 in the direction perpendicular to the cutting surface.

[0033] The embodiments are not limited to the specific type of the substrate 1, and the substrate 1 can be but is not limited to a silicon substrate. It should be noted that silicon is a common material in the prior art, and the embodiments are not limited to the internal components of the substrate 1, but directly use the silicon substrate made of the existing material.

[0034] The embodiment does not limit the specific thickness of the first passivation layer 4, for example, the thickness of the first passivation layer 4 can be less than 10nm. In order to achieve the best passivation effect, the preferred thickness of the first passivation layer 4 in the embodiment can be 1nm, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm or 9nm. The embodiment does not limit the specific type of the first passivation layer 4, as long as it can achieve the passivation effect, for example, the first passivation layer 4 can include ALO x layer. It should be noted that ALO x layer is a common material in the prior art, and the embodiment does not limit the internal components of the first passivation layer 4, but directly uses the film layer made of the existing material as the first passivation layer 4.

[0035] In order to achieve the best passivation effect, the preferred first passivation layer 4 in the embodiment can extend to the bottom surface of the step surface.

[0036] Further, in order to reduce light reflection, the surface of the first passivation layer 4 away from the emitter 2 can be provided with an anti-reflection layer. When the second passivation layer 6 extends to the surface of the first passivation layer 4 away from the emitter 2, the anti-reflection layer in the embodiment can be sandwiched between the first passivation layer 4 and the second passivation layer 6. The embodiment does not limit the specific thickness of the anti-reflection layer, for example, the thickness of the anti-reflection layer can be 80nm~90nm, and the values at both ends are included. In order to achieve the best anti-reflection effect, the preferred thickness of the anti-reflection layer in the embodiment can be 80nm, 81nm, 82nm, 83nm, 84nm, 85nm, 86nm, 87nm, 88nm, 89nm or 90nm. The embodiment does not limit the specific type of the anti-reflection layer, as long as it can reduce light reflection, for example, the anti-reflection layer can include at least one of a silicon nitride layer and a silicon oxynitride layer. It should be noted that the silicon nitride layer and the silicon oxynitride layer are common materials in the prior art, and the embodiment does not limit the internal components of the anti-reflection layer, but directly uses the film layer made of the existing material as the anti-reflection layer.

[0037] The embodiment does not limit the specific thickness of the second passivation layer 6, for example, the thickness of the second passivation layer 6 can be 5nm~50nm, and the values at both ends are included. In order to achieve the best passivation effect, the preferred thickness of the second passivation layer 6 in the embodiment can be 5nm, 6nm, 7nm, 8nm, 9nm…48nm, 49nm or 50nm. It should be noted that the thickness of the passivation layer provided on the cutting surface in the conventional solar cell is 50nm~100nm, and since the first passivation layer 4 has been provided on the side surface of the emitter 2 in the embodiment, the second passivation layer 6 does not need to be thick, so the cost can be reduced.

[0038] The embodiment is not limited to the specific type of the second passivation layer 6, as long as the passivation effect can be achieved. For example, the second passivation layer 6 can include ALO x nitrogen-aluminum oxide layer. It should be noted that the ALO layer, silicon nitride layer, silicon oxynitride layer, aluminum nitride layer, and nitrogen-aluminum oxide layer are common materials in the prior art. The embodiment is not limited to the internal components of the second passivation layer 6, but directly uses a film layer made of existing materials as the second passivation layer 6. x nitrogen-aluminum oxide layer. It should be noted that the ALO layer, silicon nitride layer, silicon oxynitride layer, aluminum nitride layer, and nitrogen-aluminum oxide layer are common materials in the prior art. The embodiment is not limited to the internal components of the second passivation layer 6, but directly uses a film layer made of existing materials as the second passivation layer 6.

[0039] Further, in order to enhance the passivation effect, one end of the second passivation layer 6 can extend to the surface of the first passivation layer 4 away from the emitter 2 and cover part of the surface of the first passivation layer 4 away from the emitter 2, and the other end of the second passivation layer 6 can extend to the surface of the substrate 1 away from the emitter 2 and cover part of the surface of the substrate 1 away from the emitter 2.

[0040] It should be noted that, in order to ensure that the extended part of the first passivation layer 4 can completely cover the side surface of the emitter 2, the height H of the side surface of the step surface is not less than the thickness of the emitter 2. When the height H of the side surface of the step surface is equal to the thickness of the emitter 2, the side surface of the step surface in the embodiment only includes the side surface of the emitter 2, and the extended part of the first passivation layer 4 only covers the side surface of the emitter 2. When the height H of the side surface of the step surface is greater than the thickness of the emitter 2, the side surface of the step surface in the embodiment can include the side surface of the emitter 2 and part of the side surface of the substrate 1, and the extended part of the first passivation layer 4 can cover the side surface of the emitter 2 and part of the side surface of the substrate 1. It should be noted that, when the height H of the side surface of the step surface is greater than the thickness of the emitter 2 in the embodiment, the protection effect of the extended part of the first passivation layer 4 on the side surface of the emitter 2 is the best. The embodiment is not limited to the specific number of step surfaces, and the specific number of step surfaces can be determined according to the actual cutting method. For example, when the solar cell is obtained by one-time cutting, a step surface can be formed on one side surface of the substrate 1, and the one side of the substrate 1 is aligned with the emitter 2, and the other side exceeds the emitter 2. When the solar cell is obtained by two-time cutting, step surfaces can be formed on the opposite side surfaces of the substrate 1, and the opposite sides of the substrate 1 both exceed the emitter 2.

[0041] The embodiment does not limit the specific height of the side surface of the step surface, as long as the height H of the side surface of the step surface is greater than the thickness of the emitter 2. For example, the height H of the side surface of the step surface can be 0.5 μm to 100 μm, and the values at both ends are included. In order to achieve the best protection effect, the preferred height H of the side surface of the step surface in the embodiment can be 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, … 99.8 μm, 99.9 μm or 100 μm. The embodiment does not limit the specific width of the bottom surface of the step surface. For example, the width D of the bottom surface of the step surface can be 0.05 μm to 50 μm, and the values at both ends are included. In order to achieve the best protection effect, the preferred width D of the bottom surface of the step surface in the embodiment can be 0.05 μm, 0.06 μm, 0.07 μm, 0.08 μm, 0.09 μm, … 49.98 μm, 49.99 μm or 50 μm. It should be noted that after the first passivation layer 4 is arranged on the side surface of the step surface, the side surface of the step surface can be flush with the side surface of the substrate 1, or it can not exceed the side surface of the substrate 1. The specific width of the side surface of the step surface and the specific thickness of the first passivation layer 4, as well as the specific thickness of the anti-reflection layer, can be determined.

[0042] In order to achieve the best passivation effect, the preferred width of the emitter 2 in the embodiment can be less than the width of the substrate 1. It should be noted that when the step surface is arranged on the cutting surface, the width direction of the emitter 2 and the substrate 1 in the embodiment should be the direction perpendicular to the cutting surface; when the step surface is arranged on the non-cutting surface, the width direction of the emitter 2 and the substrate 1 in the embodiment can be any direction in the plane perpendicular to the cutting surface. The embodiment does not limit the specific thickness of the emitter 2, as long as the thickness of the emitter 2 is less than the height H of the side surface of the step surface. For example, the thickness of the emitter 2 can be 1 μm to 2 μm, and the values at both ends are included. The preferred thickness of the emitter 2 in the embodiment can be 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm or 2 μm.

[0043] In addition to the substrate 1, the emitter 2, the first passivation layer 4 and the second passivation layer 6, the embodiment can also include other structures, which can be determined according to the specific type of solar cell. The embodiment does not limit the specific type of solar cell. For example, the solar cell can be a TOPCon cell. The embodiment does not limit the specific structure of the TOPCon cell, and the specific structure can refer to the existing TOPCon cell, which will not be described here. The embodiment does not limit the specific surface on which the emitter is arranged, and the specific surface on which the emitter is arranged can be determined according to the specific type of solar cell. For example, when the solar cell is a TOPCon cell, the emitter 2 can be arranged on the front surface of the substrate 1.

[0044] Based on the above embodiment, the height of the side surface of the step surface and the thickness of the emitter and the substrate have a suitable ratio to ensure the coverage range of the passivation layer, the first passivation layer is arranged on the surface of the emitter, the first passivation layer extends to the side surface covering the emitter, the second passivation layer is arranged on the side surface of the substrate, the second passivation layer covers the first passivation layer on the side surface of the emitter and the side surface of the substrate, and thus the multilayer passivation layer is formed on the side surface of the emitter, the side surface of the emitter is protected, and the second passivation layer does not need to be thick due to the first passivation layer arranged on the side surface of the emitter, so that the passivation effect is enhanced and the cost is reduced.

[0045] In order to make the utility model more convenient for understanding, please refer to Figures 1 to 4 The utility model discloses a preparation process of a solar cell, which specifically comprises the following steps:

[0046] 1、As Figure 2 Shown, form the emitter 2 on the front surface of the substrate 1, at this time the width of the emitter 2 is equal to the width of the substrate 1, form the emitter 2 and then groove, the initial groove 3 formed in the embodiment penetrates the emitter 2 and part of the substrate 1 along the thickness direction, can also penetrate only the emitter 2 along the thickness direction, only one initial groove 3 is formed in the embodiment, and at least two initial grooves 3 can also be formed, wherein the width of the initial groove 3 can be 0.1 μm ~ 100 μm, and the values at both ends are included, the depth of the initial groove 3 can be 0.5 μm ~ 100 μm, and the values at both ends are included, it needs to be explained that the width of the initial groove 3 is greater than the width of the bottom surface of the step surface in the embodiment, and the width of the bottom surface of the step surface is preferably equal to 1 / 2 of the width of the initial groove 3, the height of the initial groove 3 is equal to the height of the side surface of the step surface, the emitter 2 does not extend into the initial groove 3 in the embodiment because the emitter 2 is grooved on the surface after forming the emitter 2.

[0047] 2、As Figure 3 Shown, form the first passivation layer 4 on the surface of the emitter 2 away from the substrate 1 after forming the initial groove 3, the first passivation layer 4 covers the surface of the emitter 2 away from the substrate 1 and covers the inner surface of the initial groove 3, the new groove formed after the inner surface of the initial groove 3 is covered by the first passivation layer 4 is the cutting groove 5, only one cutting groove 5 is formed in the embodiment, and at least two cutting grooves 5 can also be formed, the first passivation layer 4 is formed and then metallized to form the grid line (not shown in the drawing).

[0048] 3、As Figure 4As shown, after metallization, the substrate 1 is cut (or split) at the cutting groove 5 to obtain a single solar cell. When there is only one cutting groove 5, the substrate 1 of the obtained single solar cell has a stepped surface on only one side. When there are at least two cutting grooves 5, the obtained single solar cell includes both solar cells with a stepped surface on only one side of the substrate 1 and solar cells with stepped surfaces on both opposite sides of the substrate 1.

[0049] 4. For example Figure 1 As shown, a second passivation layer 6 is formed on the cut surface of a single solar cell, so that the second passivation layer 6 covers the surface of the first passivation layer 4 on the side of the emitter 2 and the side of the substrate 1 not covered by the first passivation layer 4. At the same time, the second passivation layer 6 is deposited around the surface of the first passivation layer 4 away from the emitter 2 and the back surface of the substrate 1, so that one end of the second passivation layer 6 covers part of the surface of the first passivation layer 4 away from the emitter 2, and the other end covers part of the back surface of the substrate 1.

[0050] The solar cell fabricated using the solar cell fabrication process provided in this embodiment includes: a substrate 1; an emitter 2 disposed on the front side of the substrate 1; the width of the emitter 2 is smaller than the width of the substrate 1, and a stepped surface is formed on one side of the substrate 1; the side of the stepped surface includes the side of the emitter 2 and a portion of the side of the substrate 1; a first passivation layer 4 disposed on the surface of the emitter 2 away from the substrate 1; the first passivation layer 4 extends to the bottom surface of the stepped surface; a second passivation layer 6 is disposed on the surface of the first passivation layer 4 covering the side of the emitter 2 and the side of the substrate 1 not covered by the first passivation layer 4; one end of the second passivation layer 6 extends to the surface of the first passivation layer 4 away from the emitter 2 and covers a portion of the surface of the first passivation layer 4 away from the emitter 2; the other end of the second passivation layer 6 extends to the back side of the substrate 1 and covers a portion of the back side of the substrate 1.

[0051] This invention first sets a first passivation layer 4 on the surface of the emitter 2, extending the first passivation layer 4 to cover the side of the emitter 2, and then sets a second passivation layer 6 on the side of the substrate 1, so that the second passivation layer 6 simultaneously covers the first passivation layer 4 on both the side of the substrate 1 and the side of the emitter 2, thereby forming a multi-layer passivation layer on the side of the emitter 2, providing key protection for the side of the emitter 2. At the same time, since the first passivation layer 4 has already been set on the side of the emitter 2, the second passivation layer 6 does not need to be thick, so it can both enhance the passivation effect and reduce costs.

[0052] The present invention has provided a detailed description of a solar cell. For those skilled in the art, based on the ideas of the embodiments of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A solar cell, characterized by, The application relates to a substrate; a surface of the substrate is provided with an emitter; a step surface is formed on a side surface of the substrate; a side surface of the step surface at least comprises a side surface of the emitter; a ratio of a height H of the side surface of the step surface to a total thickness of the emitter and the substrate is 1:1.5-1:300, and the ratio comprises both ends; a first passivation layer is arranged on a surface of the emitter away from the surface of the substrate; the first passivation layer extends to the step surface; a surface of the first passivation layer covering the side surface of the emitter and a side surface of the substrate not covered by the first passivation layer are provided with a second passivation layer. The thickness of the second passivation layer is 5-50 nm, and the thickness comprises both ends. The thickness of the first passivation layer is less than 10 nm; and / or, The width of the emitter is less than the width of the substrate; and / or, 2. The solar cell according to claim 1, characterized in that, The first passivation layer extends to a bottom surface of the step surface.

3. The solar cell according to claim 1, characterized in that, The height H of the side surface of the step surface is greater than the thickness of the emitter. The height H of the side surface of the step surface is 0.5-100 mu m, and the height comprises both ends; and / or, the width D of the bottom surface of the step surface is 0.05-50 mu m, and the width comprises both ends; and / or, the thickness of the emitter is 1-2 mu m, and the thickness comprises both ends. One end of the second passivation layer extends to a surface of the first passivation layer away from the emitter, and covers part of the surface of the first passivation layer away from the emitter; the other end of the second passivation layer extends to a surface of the substrate away from the emitter, and covers part of the surface of the substrate away from the emitter.

4. The solar cell of claim 1, wherein A surface of the first passivation layer away from the emitter is provided with an anti-reflection layer.

5. The solar cell according to claim 4, characterized in that, The anti-reflection layer comprises at least one of a silicon nitride layer and a silicon oxynitride layer; and / or, the thickness of the anti-reflection layer is 80-90 nm, and the thickness comprises both ends; and / or, the anti-reflection layer is arranged between the first passivation layer and the second passivation layer. The side surface of the step surface comprises a side surface of the emitter and part of a side surface of the substrate. ​ 6. The solar cell according to any one of claims 1 to 5, wherein ​ 7. The solar cell according to any one of claims 1 to 5, wherein The first passivation layer includes ALO x layer; and / or the second passivation layer comprises ALO x at least one of a silicon layer, a silicon nitride layer, a silicon oxynitride layer, an aluminum nitride layer, an aluminum oxynitride layer.

8. The solar cell according to any one of claims 1 to 5, wherein ​ 9. The solar cell of claim 8, wherein, ​ ​ ​ 10. The solar cell according to any one of claims 1 to 5, characterized in that, ​

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