A laser system and a method for forming a solar cell

Abstract

The embodiment of the present application relates to the photovoltaic field, and provides a laser system for processing the surface of a solar cell and a forming method of the solar cell, wherein the laser system for processing the surface of the solar cell comprises: a light source module for providing a laser beam; and an optical module, the optical module comprises a plurality of lens structures, each lens structure is opposite to a to-be-processed area of an initial cell surface, the lens structure comprises opposite first and second surfaces, and the first surface faces the light source module; wherein the second surface comprises a transmission area and a reflection area, the laser beam is incident on the to-be-processed area through the transmission area and forms first reflected light, the first reflected light is transmitted to the reflection area, and at least one reflection occurs through the reflection area to form second reflected light, and the second reflected light is incident on the surface of the initial cell, which is beneficial to improve the damage caused by the laser system to the solar cell and improve the photoelectric conversion efficiency of the solar cell.

Description

Technical Field

[0001] This application relates to the photovoltaic field, and in particular to a laser system and a method for forming a solar cell. Background Technology

[0002] With the increasing severity of energy shortages, the development and utilization of renewable energy sources are urgently needed. Among numerous renewable energy sources, solar energy has outstanding advantages such as no risk of depletion, safety and reliability, no noise or pollution emissions, and its application is not limited by the geographical distribution of resources. Photovoltaic power generation is a technology that directly converts light energy into electrical energy using the photovoltaic effect at the semiconductor interface. Photovoltaic modules are the core unit of photovoltaic power generation, consisting of several solar cells encapsulated together. The performance of the solar cells affects the performance of the photovoltaic module.

[0003] However, the laser systems currently used in the production of solar cells can damage the solar cells and are not conducive to improving the photoelectric conversion efficiency of the solar cells. Summary of the Invention

[0004] This application provides a method for forming a laser system and a solar cell, which at least helps to reduce the damage caused to the solar cell by the laser system and can also improve the photoelectric conversion efficiency of the solar cell.

[0005] According to some embodiments of this application, one aspect of this application provides a laser system for processing the surface of a solar cell, comprising: a light source module for providing a laser beam; an optical module including a plurality of lens structures, each lens structure facing an area to be processed on the initial surface of the solar cell, each lens structure including a first surface and a second surface opposite to each other, the first surface facing the light source module; wherein, the second surface includes a transmission area and a reflection area, the laser beam is incident on the area to be processed through the transmission area and forms a first reflected light, the first reflected light is transmitted to the reflection area and undergoes at least one reflection through the reflection area to form a second reflected light, the second reflected light being incident on the surface of the initial solar cell.

[0006] In some embodiments, the reflective area is non-planar, and the transmissive area is planar.

[0007] In some embodiments, the reflective area is recessed toward the first surface.

[0008] In some embodiments, the reflective area is arc-shaped, and the central axis of the arc-shaped area is close to the transmissive area.

[0009] In some embodiments, the reflective area protrudes in a direction away from the first surface.

[0010] In some embodiments, the reflective area is arc-shaped, and the central axis of the arc-shaped area is away from the transmissive area.

[0011] In some embodiments, the reflective area includes a plurality of grooves extending along a first direction and arranged along a second direction, wherein the first direction is different from the second direction.

[0012] In some embodiments, the depth of the grooves arranged along the second direction increases sequentially.

[0013] In some embodiments, the ratio of the depth of the groove to the width of the groove along the second direction is less than 10.

[0014] In some embodiments, it further includes: a reflective film located on the second side of the reflective region.

[0015] In some embodiments, the first surface is a plane.

[0016] According to some embodiments of this application, another aspect of this application provides a method for forming a solar cell, comprising: providing an initial solar cell, the initial solar cell comprising a substrate and a doping source layer, the doping source layer comprising dopant ions; performing a doping process on the surface of the initial solar cell using a laser system as described above to dope the surface of the initial solar cell; preparing a passivation layer on the front side and / or the back side of the initial solar cell; performing a grooving process on the surface of the initial solar cell using the laser system to form trenches on the surface of the initial solar cell; and forming grid lines at the trench locations.

[0017] In some embodiments, the doping process includes: providing the laser beam to the doped source layer through the light source module; the laser beam incident on the surface of the doped source layer to transfer the doped ions into the substrate and form a first reflected light; the first reflected light is transmitted to the reflection region and undergoes at least one reflection via the reflection region to form a second reflected light; the second reflected light is incident on the surface of the doped source layer to transfer the doped ions into the substrate.

[0018] In some embodiments, the grooving process includes: providing the laser beam to the passivation layer through the light source module; the laser beam incident on the surface of the passivation layer to form a trench exposing the substrate and forming a first reflected light, the first reflected light being transmitted to the reflection area and undergoing at least one reflection via the reflection area to form a second reflected light, the second reflected light being incident on the surface of the passivation layer to form a trench exposing the substrate.

[0019] The technical solution provided in this application has at least the following advantages: a laser beam is provided by a light source module, the laser beam passes through the lens structure of the optical module and irradiates the area to be processed on the surface of the initial battery cell to form a first irradiation, part of the laser beam is emitted on the surface of the initial battery cell to form a first reflected light, the first reflected light is reflected back to the second surface of the lens structure, and undergoes at least one reflection on the second surface to form a second reflected light, the second reflected light irradiates the surface of the initial battery cell again, so that the surface of the initial battery cell can be irradiated multiple times, resulting in a better morphology on the surface of the battery cell, and the frequency of the laser beam can be appropriately reduced by multiple irradiations, which can also reduce the damage of the laser beam to the surface of the initial battery cell. Attached Figure Description

[0020] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments, and unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0021] Figure 1 This is a schematic diagram of the structure of a laser system provided in one embodiment of this application;

[0022] Figure 2 A cross-sectional view of a first laser system provided in an embodiment of this application;

[0023] Figure 3 A cross-sectional view of a second laser system provided in an embodiment of this application;

[0024] Figure 4 A cross-sectional view of a third laser system provided in an embodiment of this application;

[0025] Figure 5 This is a schematic diagram of another laser system provided in an embodiment of this application;

[0026] Figure 6 A cross-sectional view of a fourth laser system provided in an embodiment of this application;

[0027] Figure 7 A cross-sectional view of a fifth laser system provided in an embodiment of this application;

[0028] Figure 8 A cross-sectional view of a sixth laser system provided in an embodiment of this application;

[0029] Figure 9 A cross-sectional view of a seventh laser system provided in an embodiment of this application. Detailed Implementation

[0030] As the background technology shows, the following anomalies often occur when using laser systems to process the surface of initial solar cells: 1. High laser beam frequency: While a high laser beam frequency can result in a better morphology and more precise pattern formation on the surface of the initial solar cell, it can also damage the surface of the initial solar cell; 2. Low laser beam frequency: A low laser beam frequency can prevent the morphology formed on the surface of the initial solar cell from achieving the desired effect. Taking laser doping as an example, due to the low frequency of the laser beam, some molten material may solidify on the textured surface of the initial solar cell during the doping process, resulting in uneven sidewalls of the textured structure and reducing the photoelectric conversion efficiency of the subsequently formed solar cell.

[0031] This application provides a laser system for processing the surface of a solar cell. A laser beam is provided by a light source module. The laser beam passes through the lens structure of the optical module and is incident on the area to be processed, where it is reflected to form a first reflected light. The first reflected light irradiates the reflection area and, after at least one reflection, forms a second emitted light. The second reflected light irradiates the surface of the initial solar cell again. By reflecting the reflected light that has passed through the surface of the initial solar cell back to the surface of the initial solar cell, the initial solar cell is irradiated again by the second reflected light. Through multiple irradiations, the morphology of the structure formed on the surface of the initial solar cell is improved. This allows for the formation of a structure with a good morphology even with a low frequency laser beam. This reduces damage to the surface of the initial solar cell caused by the laser beam while ensuring a good morphology on the surface of the initial solar cell, thereby improving the photoelectric conversion efficiency of the final solar cell.

[0032] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0033] Figures 1 to 4 This is a schematic diagram of the structure of a laser system for processing the surface of a solar cell provided in an embodiment of this application, wherein... Figure 1 This application provides a schematic diagram of the structure of a laser system according to an embodiment of the present application. Figure 2 The first embodiment of this application is along Figure 1 A sectional view along the AA direction; Figure 3 The second type of edge provided for the embodiments of this application Figure 1 A sectional view along the AA direction; Figure 4 The third type of edge provided in the embodiments of this application Figure 1 A cross-sectional view along the AA direction.

[0034] refer to Figures 1 to 4 A laser system for processing the surface of a solar cell includes: a light source module 100 for providing a laser beam; and an optical module 110, which includes a plurality of lens structures 111, each lens structure 111 facing the area 121 to be processed on the surface of the initial solar cell 120. Each lens structure 111 includes a first surface 112 and a second surface 113 facing each other. The first surface 112 faces the light source module 100. The second surface 113 includes a transmission area 114 and a reflection area 115. The laser beam is incident on the area 121 to be processed through the transmission area 114 and forms a first reflected light. The first reflected light is transmitted to the reflection area 115 and undergoes at least one reflection through the reflection area 115 to form a second reflected light. The second reflected light is incident on the surface of the initial solar cell 120.

[0035] A laser beam is provided by the light source module 100. The laser beam passes through the lens structure 111 and irradiates the surface of the initial solar cell 120. The laser beam is reflected on the surface of the initial solar cell 120 to form a first reflected light. The first reflected light is transmitted to the reflection area 115 and is reflected at least once to form a second reflected light. The second reflected light irradiates the surface of the initial solar cell 120. In other words, by emitting a laser beam once, reflecting the first reflected light formed by the initial reflection on the surface of the initial solar cell 120 again, and irradiating the surface of the initial solar cell 120 again with the second reflected light, the initial solar cell 120 is irradiated at least twice with a single laser beam. By increasing the number of irradiations by the laser beam, the morphology of the initial solar cell 120 surface caused by the low laser beam frequency is compensated for, thereby reducing the damage caused by the laser beam to the surface of the initial solar cell 120 while ensuring that the surface of the initial solar cell 120 has a good morphology, which can improve the photoelectric conversion efficiency of the final solar cell.

[0036] It should be noted that the laser system provided in this application does not only achieve two irradiations. Alternatively, the second reflected light can irradiate back onto the surface of the initial solar cell 120 to form a third reflected light. The third reflected light is reflected again to the reflection area of ​​the lens structure to form a fourth reflected light. The fourth reflected light is then incident on the surface of the initial solar cell again, and so on.

[0037] In some embodiments, the light source module 100 may include a laser for emitting a laser beam, and the angle at which the laser beam is emitted can be adjusted. The laser can change the angle of the laser beam, or change the angle of the laser to change the angle at which the laser emits the laser beam. In some embodiments, the light source module 100 may also be other devices capable of providing a laser beam. This application does not limit the devices within the light source module 100, as long as they can provide a laser beam of the required frequency.

[0038] In some embodiments, the frequency of the laser beam emitted by the light source module 100 is less than 1000 kHz. Setting the frequency of the laser beam to less than 1000 kHz can reduce the damage of the laser beam to the substrate.

[0039] In some embodiments, the optical transmittance of the lens structure 111 can be greater than 99%, thereby reducing the laser beam loss as it passes through the lens structure 111. It is understood that the optical transmittance here refers to the ratio of the luminous flux of the laser beam provided by the light source module 100 to the luminous flux of the laser beam after passing through the lens structure 111.

[0040] In some embodiments, the lens structure 111 may be a glass lens, which has high optical transmittance and can reduce the light flux loss of the laser beam passing through the lens structure 111. In some embodiments, the lens structure 111 may also be a silicone lens, which has good high-temperature resistance and lower optical transmittance compared to a glass lens. This application does not limit the specific material of the lens structure 111, and the material of the lens structure 111 can be selected according to actual needs.

[0041] In some embodiments, the first surface 112 of the lens structure 111 can be referred to as the front surface of the lens structure 111, and the second surface 113 of the lens structure 111 can be referred to as the back surface of the lens structure 111. The front surface of the lens structure 111 is used to receive a laser beam, and the back surface is used to reflect the first reflected light to form a second reflected light and reflect the second reflected light to the surface of the initial battery cell 120.

[0042] In some embodiments, the light source module 100 and the optical module 110 may be spaced apart, that is, the transmission path of the laser beam is such that the light source module 100 generates the laser beam, which is then irradiated by the optical module 110 via the air, and then the optical module 110 forms the first reflected light and irradiates the surface of the initial battery cell 120. By setting the space between the light source module 100 and the optical module 110, the light source module can be flexibly moved, thereby allowing one light source module to provide a laser beam to multiple lens structures 111.

[0043] In some embodiments, the transmission direction of the laser beam can be perpendicular to the first surface 112 of the lens structure 111. It is understood that although the laser beam will be refracted when it enters the optical module 110 from the air, it will be refracted again when it exits the optical module 110. Therefore, by setting the transmission direction of the laser beam to be perpendicular to the first surface 112 of the lens structure 111, the laser beam emitted through the lens structure 111 can be emitted in a direction perpendicular to the first surface 112.

[0044] In some embodiments, the light source module 100 and the optical module 110 may also be in contact connection, that is, the light source module 100 and the first surface of the lens structure 111 are in contact connection. It can be understood that if the laser beam is emitted directly from the lens structure 111 into the air, the laser beam will be deflected. Therefore, the incident angle of the laser beam and the material of the lens structure 111 can be adjusted so that the laser beam emitted through the lens structure 111 is emitted in a direction perpendicular to the first surface 112. By setting the light source module 100 and the optical module 110 to be in contact connection, the loss of the laser beam in the air can be reduced.

[0045] In some embodiments, the first surface 112 of the lens structure 111 is planar. It is understood that by making the first surface 112 of the lens structure 111 planar, the deflection of the laser beam as it passes through the first surface 112 can be minimized. Furthermore, making the first surface 112 planar prevents changes in the incident angle of the laser beam, thereby avoiding any impact on the irradiation effect of the laser beam on the surface of the initial solar cell 120. In some embodiments, the first surface 112 of the lens structure 111 may also be slightly concave towards the second surface 113.

[0046] It should be noted that the plane mentioned above refers to the first surface 112 of the lens structure 111 being completely flat, or the flatness of the first surface 112 being within the allowable error range. When the flatness of the first surface 112 is within the allowable error range, the surface of the first surface 112 can also be regarded as a plane.

[0047] In some embodiments, the reflective area 115 is non-planar and the transmissive area 114 is planar. The laser beam irradiates the lens structure 111 and leaves the surface of the lens structure 111 via the transmissive area 114. By setting the transmissive area 114 to be planar, the laser beam will not be deflected due to the surface of the transmissive area 114. By setting the reflective area 115 to be non-planar, the first reflected light formed by the processing area 121 of the initial battery cell 120 can be reflected back to the processing area 121 as much as possible.

[0048] In some embodiments, the first surface 112 of the lens structure 111 is a plane, the transmission area 114 is a plane, and the first surface 112 is parallel to the transmission area 114. This ensures that the laser beam will not have an incident angle shift due to the surface structure of the lens structure 111. In other words, without considering the difference between air and the medium of the lens structure 111, the transmission direction of the laser beam incident on the lens structure 111 and the laser beam passing through the lens structure 111 does not change. This ensures that the laser beam will not have an angle shift after passing through the lens structure 111, thereby improving the reliability of the solar cell manufacturing process.

[0049] It should be noted that the above-mentioned transmission area 114 being a plane means that the surface of the transmission area 114 of the second surface 113 is completely flat, or the flatness of the surface of the transmission area 114 is within the allowable error range. When the flatness of the surface of the transmission area 114 is within the allowable error range, the surface of the transmission area 114 can also be regarded as a plane.

[0050] In some embodiments, the reflective region 115 is recessed toward the first surface 112, meaning that the bottom surface of the reflective region 115 is closer to the first surface 112 than the transmissive region 114. In other words, in the direction perpendicular to the first surface 112, the thickness of the transmissive region 114 is greater than the thickness of the reflective region 115. By setting the reflective region 115 to be recessed toward the first surface 112, the first reflected light formed by the processing area 121 of the initial battery cell 120 can be reflected back to the processing area 121 as much as possible, thereby increasing the number of times the processing area 121 of the initial battery cell 120 is irradiated, so that the surface of the initial battery cell 120 has a good morphology.

[0051] In some embodiments, the reflective area 115 may be recessed toward the first surface 112, provided that the reflective area 115 is non-planar and the transmissive area 114 is planar. Alternatively, the reflective area 115 may be recessed toward the first surface 112, provided that the reflective area 115 is non-planar and the transmissive area 114 is non-planar.

[0052] In some embodiments, reference Figure 1 The reflective area 115 is arc-shaped, and the central axis of the arc surface is close to the transmission area 114. In other words, the arc surface includes a side close to the transmission area 114 and a side away from the transmission area 114, with the side close to the transmission area 114 being lower than the side away from the transmission area 114. By setting the reflective area 115 to be arc-shaped, and with the central axis of the arc surface facing the transmission area 114, the first reflected light can be reflected back to the processing area 121 of the initial solar cell 120 as much as possible, thereby processing the processing area 121 again and improving the morphology of the formed solar cell surface.

[0053] It is understandable that an arc surface is a surface formed by extending an arc in a certain direction, and the central axis here refers to the central axis formed by extending the center of the arc in the same direction.

[0054] In some embodiments, reference Figure 4 With the reflective area 115 recessed towards the first surface 112, the shape of the reflective area 115 in the direction perpendicular to the first surface 112 can also be a zigzag shape. The zigzag-shaped reflective area 115 can be recessed from the two sides of the reflective area 115 toward the middle of the reflective area 115. By setting the shape of the reflective area 115 in the direction perpendicular to the first surface 112 to be a zigzag shape, the first reflected light can be reflected back to the processing area 121 of the initial solar cell 120 as much as possible, so that the processing area 121 can be processed again, thereby improving the morphology of the surface of the formed solar cell.

[0055] refer to Figure 3 In some embodiments, the reflective area 115 is curved, and the curved surface is composed of multiple interconnected arc surfaces. Taking the curved surface as an example, the three curved surfaces are the first curved surface, the second curved surface, and the third curved surface. The first curved surface is connected to the second curved surface, and the second curved surface is connected to the third curved surface. By setting the curved surface of the reflective area 115 to be composed of multiple interconnected arc surfaces, multiple beams of second reflected light can be reflected to the same point of the initial battery cell 120. It is understood that as the reflection proceeds, the energy of the laser beam will gradually decrease. By reflecting multiple beams of second reflected light to the same point of the initial battery cell 120, the irradiation effect of the second reflected light can be improved by irradiating the same point of the initial battery cell 120 with multiple beams of second reflected light.

[0056] In some embodiments, multiple arc surfaces are recessed toward the first surface 112, that is, the arc surfaces and curved surfaces are recessed in the same direction, so as to reflect the first reflected light back to the processing area 121 of the initial solar cell 120 as much as possible, thereby improving the morphology of the formed solar cell surface.

[0057] In some embodiments, the central axes of the multiple arc surfaces can be arranged along a certain trajectory, such as the central axes of the multiple arc surfaces can be arranged along a parabola. By setting the central axes of the multiple arc surfaces to be arranged along a certain trajectory, the transmission path of the second reflected light can be simulated before the lens structure is formed. This makes it easier to simulate the irradiation effect of the arc surface structure on the initial battery cell 120, thereby allowing adjustments to the position or size of the arc surface structure, which can improve the irradiation effect of the lens structure 110.

[0058] In some embodiments, a reflective film 130 may also be included, which is located in the reflective region 115. By providing the reflective film 130 in the reflective region 115, the reflectivity of the reflective region 115 can be improved, thereby reflecting more of the first reflected light back to the initial solar cell 120 and reducing the loss caused by the refraction and scattering of the laser beam in the reflective region 115.

[0059] In some embodiments, the optical module 110 may further include a connection structure 116 for connecting adjacent lens structures 111, and the connection structure 116 is directly opposite to the structures on the initial battery cell 120 that do not require processing.

[0060] In some embodiments, the connection structure 116 may be configured to be non-transparent, that is, the laser beam will undergo total internal reflection when it shines on the surface of the connection structure 116, so that the laser beam will not penetrate the connection structure 116 and shine on the surface of the initial battery cell 120, or, after the laser beam passes through the connection structure 116, most of the energy of the laser beam is consumed, so that the laser beam will not affect the surface structure of the initial battery cell 120.

[0061] In some embodiments, the connection structure 116 can also be configured to be light-transmitting, so that the initial battery cell 120 located below the connection structure 116 can be prevented from being illuminated by controlling the light source module 100 not to provide a laser beam to the connection structure 116, thereby improving the reliability of the initial battery cell 120.

[0062] This disclosure provides a laser system for processing the surface of a solar cell. By setting the reflective area 115 to be recessed towards the first surface 112, the angle of the second reflected light formed through the reflective area 115 can be controlled, so that the second reflected light can irradiate the area 121 to be processed of the initial solar cell 120. This can be achieved by increasing the number of laser beam irradiations to compensate for the low laser beam frequency, which prevents the surface morphology of the initial solar cell 120 from achieving the desired effect. This reduces the damage caused by the laser beam to the surface of the initial solar cell 120 while ensuring that the surface of the initial solar cell 120 has a good morphology, thereby improving the photoelectric conversion efficiency of the final solar cell.

[0063] This application also provides another laser system for processing the surface of solar cells. The other laser system for processing the surface of solar cells provided in this application is generally the same as the aforementioned embodiment. The main differences include: the reflective area in this application embodiment protrudes in a direction away from the first surface. The other identical or corresponding parts can be referred to the above embodiment. The semiconductor structure provided in another embodiment of this application will be described in detail below with reference to the accompanying drawings.

[0064] refer to Figures 5 to 9,in, Figure 5 This is a schematic diagram of the structure of the laser system provided in the embodiments of this application; Figure 6 The following are provided for the embodiments of this application: Figure 5 Cross-sectional view of the fourth laser system in the AA direction; Figure 7 The following are provided for the embodiments of this application: Figure 5 Cross-sectional view of the fifth type of laser system in the AA direction; Figure 8 The following are provided for the embodiments of this application: Figure 5 Cross-sectional view of the sixth type of laser system in the AA direction; Figure 9 The following are provided for the embodiments of this application: Figure 5 Cross-sectional view of the laser system in the BB direction.

[0065] In some embodiments, the reflective region 115 protrudes in a direction away from the first surface 112. That is, compared to the transmissive region 114, the bottom surface of the reflective region 115 is farther away from the first surface 112. In other words, in a direction perpendicular to the first surface 112, the thickness of the transmissive region 114 is less than the thickness of the reflective region 115. By setting the reflective region 115 to protrude in a direction away from the first surface 112, the first reflected light formed by the treatment area 121 of the initial battery cell 120 can be reflected back to the treatment area 121 as much as possible, thereby increasing the number of times the treatment area 121 of the initial battery cell 120 is irradiated, so that the surface of the initial battery cell 120 has a good morphology.

[0066] In some embodiments, the reflective region 115 is arc-shaped, and the central axis of the arc-shaped surface is away from the transmission region 114. In other words, the arc-shaped surface includes a side closer to the transmission region 114 and a side farther from the transmission region 114, with the side closer to the transmission region 114 being higher than the side farther from the transmission region 114. By setting the reflective region 115 to be arc-shaped, and with its central axis farther from the transmission region 114, the first reflected light can be reflected back to the processing area 121 of the initial solar cell 120 as much as possible, thereby allowing the processing area 121 to be processed again and improving the morphology of the formed solar cell surface.

[0067] It is understood that the reflective area 115 protrudes in a direction away from the first surface 112, and the central axis of the arc surface is away from the transmission area 114, so that the convex surface of the arc surface faces the processing area 121 of the initial solar cell 120, thereby reflecting the first reflected light back to the processing area 121 of the initial solar cell 120 as much as possible, so that the processing area 121 can be processed again, which can improve the morphology of the surface of the formed solar cell.

[0068] In some embodiments, the reflective area 115 is a curved surface, and the curved surface is composed of multiple interconnected arc surfaces. Taking the curved surface as an example, the three curved surfaces are the first curved surface, the second curved surface, and the third curved surface. The first curved surface is connected to the second curved surface, and the second curved surface is connected to the third curved surface. By setting the curved surface of the reflective area 115 to be composed of multiple interconnected arc surfaces, multiple beams of second reflected light can be reflected to the same point of the initial battery cell 120. It is understood that as the reflection proceeds, the energy of the laser beam will gradually decrease. By reflecting multiple beams of second reflected light to the same point of the initial battery cell 120, the irradiation effect of the second reflected light can be improved by irradiating the same point of the initial battery cell 120 with multiple beams of second reflected light.

[0069] In some embodiments, the reflective area 115 includes a plurality of grooves 117 extending along a first direction and arranged along a second direction. The first direction is different from the second direction. It can be understood that the area to be processed 121 of the initial battery cell 120 refers to a part of the surface of the initial battery cell. That is, the area to be processed 121 includes length and width in two dimensions. Taking the first direction as the width direction of the area to be processed 121 and the second direction as the length direction of the area to be processed 121 as an example, by setting the grooves 117 to be arranged along the second direction, the second reflected light can be reflected to the structural surface of the area to be processed 121 arranged along the length direction, thereby improving the surface structure of the area to be processed 121 along the length direction.

[0070] In some embodiments, the grooves 117 may also be arranged along a first direction and a second direction.

[0071] In some embodiments, the depth of the grooves 117 arranged along the second direction increases sequentially, that is, the recessed degree of the grooves 117 arranged along the second direction becomes deeper and deeper. For example, the depth of the first groove arranged along the second direction can be 100 μm, the depth of the second groove can be 110 μm, and so on, increasing sequentially. By setting the depth of the grooves 117 to increase sequentially, the light flux of the second reflected light can be increased, thereby improving the morphology of the surface of the formed solar cell.

[0072] In some embodiments, the depth of the grooves 117 arranged along the second direction can increase in an arithmetic progression, wherein the tolerance of the arithmetic progression can be adjusted according to the actual situation.

[0073] In some embodiments, the depth of the groove 117 can be 50~1000μm, such as 100μm, 150μm and 200μm. By setting the depth of the groove 117 to 50~1000μm, the second reflected light can be controlled as much as possible within the processing area 121 of the initial battery cell, and the second reflected light can be prevented from shining on the part outside the processing area 121.

[0074] In some embodiments, the width of the groove 117 can be 5~100μm, such as 10μm, 30μm or 80μm. It is understood that for a given size of lens structure, the larger the width of the groove 117, the smaller the size of the transmission area 114. When the width of the groove 117 is greater than 100μm, the opening of the groove 117 is larger, and the size of the transmission area 114 is reduced, which may affect the opening size of the laser beam passing through the transmission area 114 to irradiate the area to be processed 121, and may cause the second reflected light to be reflected to areas outside the area to be processed of the initial battery cell 120. The smaller the width of the groove 117, the smaller the area used to receive the first reflected light, and the less second reflected light is formed, and the worse the ability to improve the surface morphology of the initial battery cell 120 is. Therefore, by controlling the width of the groove 117 to be 5~40μm, it is possible to have a good ability to improve the surface morphology of the initial battery cell 120 while avoiding affecting the laser beam passing through the transmission area 114.

[0075] In some embodiments, the ratio of the depth of the groove 117 to the width of the groove 117 along the second direction is less than 10. It is understood that when the ratio of the depth of the groove 117 to the width of the groove 117 is greater than 10, the second reflected light may irradiate parts outside the area to be processed. By controlling the ratio of the depth of the groove 117 to the width of the groove 117 along the second direction to be less than 10, the second reflected light can be controlled to be reflected as much as possible to the area to be processed 121 to improve the morphology of the formed solar cell and thus improve the performance of the solar cell.

[0076] It is understood that the depth and width mentioned above are the maximum depth and maximum width within the groove.

[0077] In this embodiment, by setting the reflective area 115 to protrude in a direction away from the first surface 112, the angle of the second reflected light formed through the reflective area 115 can be controlled. This allows the second reflected light to irradiate the processing area 121 of the initial solar cell 120. By increasing the number of laser beam irradiations, the morphology of the initial solar cell 120 surface, which is not as expected due to the low laser beam frequency, can be balanced. This achieves the goal of reducing damage to the surface of the initial solar cell 120 while ensuring a good morphology, thereby improving the photoelectric conversion efficiency of the final solar cell.

[0078] Accordingly, another embodiment of this application also provides a method for forming a solar cell. The method for forming a solar cell provided in another embodiment of this application uses a laser system as described in the above embodiments to process the surface of the initial cell. The parts that are the same as or corresponding to the above embodiments can be referred to the above embodiments, and will not be repeated below.

[0079] In some embodiments, a method for forming a solar cell includes: providing an initial solar cell, the initial solar cell including a substrate and a doping source layer, the doping source layer including dopant ions; performing a surface doping process on the initial solar cell using a laser system as described in the above embodiments to dope the surface of the initial solar cell; preparing a passivation layer on the front and / or back side of the initial solar cell; performing a grooving process on the surface of the initial solar cell using a laser system as described in the above embodiments to form trenches on the surface of the initial solar cell; and forming grid lines at the trench locations. By using a laser system as described in the above embodiments to perform a doping process on the initial solar cell, damage caused by the laser beam to the surface of the initial solar cell can be reduced. By using a second reflected light to further process the surface of the initial solar cell, the surface morphology of the formed solar cell can be improved. By using a laser system to perform the grooving process in the above embodiments, the depth of the formed trenches can be shallowed, reducing damage to the surface of the initial solar cell, reducing the metal contact area and lateral resistance on the back side of the solar cell, and improving the performance of the subsequently formed solar cell.

[0080] In some embodiments, the doping process includes: providing a laser beam to the doped source layer via a light source module; the laser beam incident on the surface of the doped source layer and forming a first reflected light, the first reflected light being transmitted to a reflective region and undergoing at least one reflection via the reflective region to form a second reflected light, the second reflected light being incident on the surface of the doped source layer to transfer dopant ions into the substrate. By employing a laser system as described above to complete the doping process, and by employing a multiple doping method, damage to the substrate from the laser beam can be reduced, recombination losses in the initial solar cell can be reduced, and contact resistance can be reduced.

[0081] Taking boron diffusion as an example, the steps for providing the initial solar cell include: cleaning and texturing an N-type or P-type substrate to form a textured surface with a reflectivity of 8.0-10.5%; depositing a boron-containing thin-film doped source layer with a thickness of 20nm-60nm; and using a laser system as described above to provide a high-frequency (2-30MHz), short-pulse-width (5-12ps) laser beam to laser dope the surface of the initial solar cell. In related technologies, laser doping often causes significant damage to the textured pyramids. However, by using the laser system described above to complete the doping process, the sheet resistance of the doped region formed on the surface of the initial solar cell can be reduced by 30-50Ω. Furthermore, the damage width at the top of the textured pyramid on the solar cell surface can be less than 0.3μm. Therefore, the reflectivity of the treated area after laser doping only increases by 0.4%-1.3%, and when the sheet resistance is reduced by 40Ω, the average increase in reflectivity of the laser-doped area is less than 1.0%.

[0082] Refer to Table 1 below, which shows the parameters of solar cells after laser doping in related technologies.

[0083]

[0084] Table 1

[0085] Referring to Table 2 below, Table 2 shows the performance of the battery cells manufactured by the laser system in the embodiments of this application.

[0086]

[0087] Table 2

[0088] It should be noted that the minority carrier lifetime described above characterizes the passivation level, and the open-circuit voltage refers to a standard light intensity condition of 1 kW / m². 2 The test was conducted under the specified conditions.

[0089] As can be seen from the table, the minority carrier lifetime, open-circuit voltage, and fill factor provided by the embodiments of this application are all increased accordingly, while the short-circuit current density is reduced, thus improving the performance of the formed solar cell.

[0090] In some embodiments, the trenching process includes: providing a laser beam to a passivation layer via a light source module; the laser beam incident on the surface of the passivation layer and forming a first reflected light, the first reflected light being transmitted to a reflection area and undergoing at least one reflection via the reflection area to form a second reflected light, the second reflected light being incident on the surface of the passivation layer to form a trench exposing the substrate. By employing a laser system to form trenches on the surface of the initial solar cell, the formed trenches are relatively shallow, which can reduce damage to the surface of the initial solar cell, reduce the metal contact area and lateral resistance on the back of the solar cell, and reduce the high-speed recombination region at the semiconductor interface between the metal and the initial solar cell, thereby improving the short-circuit current and open-circuit voltage.

[0091] In some embodiments, ultraviolet or green light can be used to laser-groove the passivation layer on the surface of the initial solar cell during the grooving process. The laser beam scanning speed can be 35-50 m / s, the laser beam power can be 50-80 W, the frequency can be 100 kHz-3000 kHz, and the laser beam pulse width can be 5 ps-12 ps. Related technologies produce grooves with an average linewidth of 43 μm and an average depth of 12 μm. The laser grooving process described above can achieve an average linewidth of 38 μm and an average depth of 9 μm, meaning the damage depth to the initial solar cell is less than 10 μm. This improves the reliability of the resulting solar cell when the initial solar cell is thinner, allows for the formation of low-resistance ohmic contacts in the metallization paste, and enhances the conversion efficiency of the solar cell.

[0092] Those skilled in the art will understand that the above-described embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail may be made without departing from the spirit and scope of this application. Any person skilled in the art can make their own modifications and alterations without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A laser system for processing the surface of a solar cell, characterized in that, include: The light source module is used to provide the laser beam; An optical module includes multiple lens structures, each lens structure facing the area to be processed on the surface of the initial battery cell. Each lens structure includes a first surface and a second surface facing each other, with the first surface facing the light source module. The second surface includes a transmission area and a reflection area. The laser beam is incident on the area to be processed through the transmission area and forms a first reflected light. The first reflected light is transmitted to the reflection area and undergoes at least one reflection through the reflection area to form a second reflected light. The second reflected light is incident on the surface of the initial battery cell. Wherein, the reflective area is non-planar, the transmissive area is planar, and the transmission direction of the laser beam is perpendicular to the first surface of the lens structure; The reflective area protrudes in a direction away from the first surface; The reflective area includes multiple grooves that extend along a first direction and are arranged along a second direction. The first direction is different from the second direction. The first direction is the width direction of the area to be processed, and the second direction is the length direction of the area to be processed. The depth of the grooves arranged along the second direction increases sequentially.

2. The laser system according to claim 1, characterized in that, The ratio of the depth of the groove to the width of the groove along the second direction is less than 10.

3. The laser system according to claim 1, characterized in that, Also includes: A reflective film located in the reflective region.

4. The laser system according to claim 1, characterized in that, The first surface is a plane.

5. A method for forming a solar cell, comprising: An initial solar cell is provided, the initial solar cell comprising a substrate and a doped source layer, the doped source layer comprising doped ions; The surface of the initial solar cell is doped using the laser system described in any one of claims 1 to 4. A passivation layer is prepared on the front and / or back of the initial solar cell; A grooving process is performed on the surface of the passivation layer using the laser system as described in any one of claims 1 to 4 to form a trench on the surface of the initial battery cell; A grid line is formed at the trench location.

6. The method for forming a solar cell according to claim 5, characterized in that... The doping process includes: The laser beam is provided to the doped source layer through the light source module; The laser beam is incident on the surface of the doped source layer to transfer the doped ions into the substrate and form a first reflected light. The first reflected light is transmitted to the reflection region and undergoes at least one reflection through the reflection region to form a second reflected light. The second reflected light is incident on the surface of the doped source layer to transfer the doped ions into the substrate.

7. The method for forming a solar cell according to claim 6, characterized in that... The grooving process includes: The laser beam is provided to the passivation layer through the light source module; The laser beam is incident on the surface of the passivation layer to form a trench exposing the substrate and to form a first reflected light. The first reflected light is transmitted to the reflection area and undergoes at least one reflection via the reflection area to form a second reflected light. The second reflected light is incident on the surface of the passivation layer to form a trench exposing the substrate.

Images