CN220543926U - Solar cell and photovoltaic module - Google Patents

Abstract

The application relates to a solar cell and photovoltaic module, include: a substrate having a light receiving surface and a light back surface arranged opposite to each other; a back electrode structure located on the back light surface of the substrate; the front passivation structure is positioned on the light receiving surface of the substrate; the first electrode grid lines are positioned in the first film opening area of the front passivation structure to form ohmic contact with the substrate, and are arranged at intervals along the first direction; the second electrode grid lines are positioned on one side of the front passivation structure, away from the substrate, and are used for connecting two adjacent first electrode grid lines in the first direction; in the second direction, the size of the second electrode grid line is smaller than that of the first electrode grid line. The first electrode grid lines with larger size form good ohmic contact with the substrate, so that the conducting channels of the first electrode grid lines and the substrate can efficiently conduct out the current in the battery, and the second electrode grid lines with smaller size are arranged between the adjacent first electrode grid lines so as to reduce the shading area of the grid lines, thereby improving the optical absorption of the battery.

Description

Solar cells and photovoltaic modules

Technical field

This application relates to the field of semiconductor technology, and in particular to a solar cell and photovoltaic module.

Background technique

With the rapid development of photovoltaic industrialization technology, there are technological updates in all manufacturing links. New technologies and new processes bring lower costs and better product performance. Among them, solar cells with passivated contact structures can provide good Surface passivation and reduction of metal contact recombination currents have received increasing attention in the photovoltaic market. However, when the existing manufacturing process prints aluminum paste on the front of the battery to be used as the positive electrode, the particle size of the aluminum paste is too large, which increases the printing width of the front electrode, thereby reducing the light-receiving area of the solar cell surface, resulting in poor optical performance of the cell. The loss is larger, thereby reducing the photoelectric conversion efficiency of the solar cell.

Utility model content

Based on this, it is necessary to provide a solar cell that solves the problem in the prior art that the aluminum paste particle size is too large, which increases the printing width of the front electrode, thereby reducing the light-receiving area of the solar cell surface, resulting in greater optical loss of the cell. and photovoltaic modules.

In order to achieve the above purpose, this application provides a solar cell, including:

The substrate has a light-receiving surface and a backlight surface arranged oppositely;

A back electrode structure located on the backlight surface of the substrate;

A front passivation structure located on the light-receiving surface of the substrate;

A plurality of first electrode grid lines located in the first open film area of the front-side passivation structure to form ohmic contact with the substrate, the plurality of first electrode grid lines being spaced apart along the first direction;

A plurality of second electrode grid lines, located on the side of the front passivation structure away from the substrate, used to connect two adjacent first electrode grid lines in the first direction;

Wherein, in the second direction, the size of the second electrode grid line is smaller than the size of the first electrode grid line, and the first direction is perpendicular to the second direction.

In one embodiment, the plurality of first electrode grid lines extend along the first direction and are arranged at equal intervals in sequence.

In one embodiment, the first electrode grid line includes:

A first doping layer is located in the first opening area of the front passivation structure to inject into the upper surface layer of the light-receiving surface of the substrate. The doping type of the first doping layer is consistent with the doping of the substrate. Same type;

A metal electrode layer is stacked on a side surface of the first doped layer away from the substrate. The metal electrode layer forms ohmic contact with the substrate through the first doped layer. Two adjacent metal electrode layers are electrically connected through the second electrode gate line;

Wherein, the doping concentration of the first doping layer is greater than the doping concentration of the substrate.

In one embodiment, the front passivation structure includes:

Passivation layer, located on the light-receiving surface of the substrate;

An anti-reflection layer, located on the side of the passivation layer away from the substrate;

Wherein, the first film-opening area is opened on the anti-reflection layer and penetrates the anti-reflection layer and the passivation layer in sequence.

In one embodiment, the second electrode grid line is a metal silver grid line.

In one embodiment, the ratio between the area of the first open film area of the front passivation structure and the area of the light-receiving surface of the substrate is lower than a preset threshold.

In one embodiment, the back electrode structure includes:

A backside passivation structure located on the backlight surface of the substrate;

A back electrode is located on a side of the back passivation structure away from the substrate.

In one embodiment, the backside passivation structure includes:

A tunnel oxide layer located on the backlight surface of the substrate;

a second doped layer, located on a side surface of the tunnel oxide layer away from the substrate, the doping type of the second doping layer being different from the doping type of the substrate;

Wherein, the back electrode is located on a side of the second doped layer away from the substrate and is in contact with the second doped layer.

In one embodiment, the backside passivation structure further includes:

A dielectric layer is located on a side surface of the second doped layer away from the substrate, and the dielectric layer is provided with a plurality of second open film regions;

Wherein, the number of the back electrodes is multiple, each of the back electrodes is located corresponding to one of the second open film areas to contact the second doped layer, and each of the back electrodes is arranged along the first direction. Arranged in a grid pattern.

The present application provides a photovoltaic component, including the solar cell as described above.

In the above-mentioned solar cells and photovoltaic modules, a plurality of first electrode grid lines are arranged at intervals along the first direction in the first open film area of the front passivation structure, and the second electrode grid lines are on the side of the front passivation structure facing away from the substrate. The surface is connected to two adjacent first electrode grid lines. Since the size of the second electrode grid line is smaller than the size of the first electrode grid line on the light-receiving surface of the substrate, on the one hand, the larger size of the first electrode grid line A good ohmic contact is formed between the line and the substrate, so that the conductive channel between the first electrode grid line and the substrate can more efficiently conduct the current inside the cell. On the other hand, the smaller size of the second electrode grid line It is provided between adjacent first electrode grid lines to reduce the light-shielding area of the grid lines, thereby further improving the optical absorption of the solar cell and helping to improve the photoelectric conversion efficiency of the cell.

Description of drawings

In order to more clearly explain the technical solutions in the embodiments of the present application or the traditional technology, the drawings needed to be used in the description of the embodiments or the traditional technology will be briefly introduced below. Obviously, the drawings in the following description are only for the purpose of explaining the embodiments or the technical solutions of the traditional technology. For some embodiments of the application, those of ordinary skill in the art can also obtain other drawings based on these drawings without exerting creative efforts.

Figure 1 is a schematic structural diagram of a solar cell provided in an embodiment;

Figure 2 is a second structural schematic diagram of a solar cell provided in an embodiment;

FIG. 3 is a third structural schematic diagram of a solar cell provided in an embodiment.

Explanation of reference symbols:

Substrate: 100; light-receiving surface: 110; backlight surface: 120; back electrode structure: 200; back passivation structure: 210; tunnel oxide layer: 211; second doped layer: 212; dielectric layer: 213; back electrode : 220; front passivation structure: 300; passivation layer: 310; anti-reflection layer: 320; first electrode grid line: 400; first doping layer: 410; metal electrode layer: 420; second electrode grid line: 500.

Detailed ways

In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are given in the accompanying drawings. However, the present application may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing specific embodiments only and is not intended to limit the application.

As used herein, the singular forms "a," "an," and "the" may include the plural forms as well, unless the context clearly dictates otherwise. It will also be understood that the terms "comprising" or "having" and the like specify the presence of stated features, integers, steps, operations, components, parts or combinations thereof, but do not exclude the presence or addition of one or more Possibility of other features, integers, steps, operations, components, parts or combinations thereof. Also, in this specification, the term "and/or" includes any and all combinations of the associated listed items.

It should be noted that when an element is referred to as being "disposed on" or "located on" another element, it can be directly on the other element or intervening elements may also be present. When an element is said to be "connected" to another element, it can be directly connected to the other element or there may also be intervening elements present.

Referring to Figure 1, the present application provides a solar cell, including: a substrate 100, a back electrode structure 200, a front passivation structure 300, a plurality of first electrode grid lines 400 and a plurality of second electrode grid lines (not shown in Figure 1 shown), the substrate 100 has a light-receiving surface 110 and a backlight surface 120 arranged oppositely, the back electrode structure 200 is located on the backlight surface 120 of the substrate 100, the front passivation structure 300 is located on the light-receiving surface 110 of the substrate 100, and a plurality of An electrode grid line 400 is located in the first open film area of the front passivation structure 300 to form ohmic contact with the substrate 100, and a plurality of first electrode grid lines 400 are arranged at intervals along the first direction. A plurality of second electrode gate lines are located on the side of the front passivation structure 300 away from the substrate 100 and are used to connect two adjacent first electrode gate lines 400 in the first direction. In the second direction, the second electrode gate lines The size of the gate line is smaller than the size of the first electrode gate line 400, and the first direction is perpendicular to the second direction.

The substrate 100 serves as a region that absorbs incident photons and generates photogenerated carriers, which may include one or more of monocrystalline silicon, polycrystalline silicon, and microcrystalline silicon. The light-receiving surface 110 of the substrate 100 is the front side, referring to It is the side surface of the solar cell that receives light. The backlight surface 120 of the substrate 100 is the back surface that is opposite to the light-receiving surface 110 , and refers to the side surface of the solar cell facing away from the light. The back electrode structure 200 is disposed on the backlight surface 120 of the substrate 100 to form a PN junction on the back of the battery to separate photogenerated carriers into electrons and holes, thereby avoiding optical losses caused by forming a highly doped emitter on the front of the battery and improving The utilization rate of incident light is conducive to improving the photoelectric conversion efficiency of solar cells.

Furthermore, impurities and defects inside and on the surface of the silicon wafer of the substrate 100 will have a negative impact on the performance of the battery. By arranging the front passivation structure 300 on the light-receiving surface 110 of the substrate 100, the recombination of surface carriers can be reduced, thereby reducing The impact of small defects ensures the working efficiency of the battery. 1 and 2, the front passivation structure 300 is provided with a plurality of front metal partial contact areas arranged at intervals along the first direction X. The front metal partial contact areas are called first film-opening areas. It is used to form the first electrode gate line 400, that is, the first electrode gate line 400 penetrates the front passivation structure 300 to contact the substrate 100, and the contact area forms a high-low junction, so that the electron-vacancy on the front side of the substrate 100 The hole pairs accelerate diffusion toward the backside PN junction, which is beneficial to improving the collection efficiency of photogenerated carriers and reducing the recombination efficiency on the front side of the substrate 100 .

Further, please refer to FIGS. 1 and 3 , the second electrode grid line 500 is located on the surface of the front passivation structure 300 to connect the two adjacent first electrode grid lines 400 , so that the first electrode grid line 400 and the first electrode grid line 400 are connected to each other. The two-electrode grid lines 500 form the front electrode of the solar cell in a structure alternately arranged in the first direction X. The front electrode and back electrode structures 200 can form electrical contact with external devices to collect current in the solar cell. , that is, the light incident on the PN junction on the back side of the substrate 100 serves as an external energy source to generate electron-hole pairs in the substrate 100. Since there is a potential difference in the PN junction, the electrons and holes are driven in opposite directions by the internal potential difference. Moving in the direction, electrons move to the negative contact and holes move to the positive contact, thereby generating a current that delivers power to external devices.

Furthermore, in order to avoid an increase in the shielding area of the front side of the cell due to an excessively wide printing width during front electrode printing, this embodiment sets the size of the second electrode grid line 500 in the second direction Y to be smaller than the first electrode grid line. The size of 400, where the size in the second direction Y can be understood as the width of the gate line, setting a larger size of the first electrode gate line 400 in the first film opening area can form a good ohmic contact with the substrate 100 , so that the conductive channel between the first electrode grid line 400 and the substrate 100 can more efficiently conduct the current inside the cell piece, and a smaller size second electrode grid is used between adjacent first electrode grid lines 400 By connecting the lines 500, the printing width of the connection area can be reduced to reduce the shielding area of the electrode grid lines. Therefore, the first electrode grid lines 400 and the second electrode grid lines 500 extend in a structure with uneven sizes in the first direction X. , can reduce the optical loss of the cell and increase the optical absorption of the cell, thereby improving the working performance of the solar cell.

In the above example, the plurality of first electrode gate lines 400 are spaced apart along the first direction in the first film-opening area of the front passivation structure 300 , and the second electrode gate lines 500 are away from the substrate 100 in the front passivation structure 300 One side surface of the substrate 100 is used to connect two adjacent first electrode grid lines 400. Since the light-receiving surface 110 of the substrate 100 adopts a structure in which the size of the second electrode grid line 500 is smaller than the size of the first electrode grid line 400, on the one hand, The larger size of the first electrode grid line 400 can form a good ohmic contact with the substrate 100, so that the conductive channel between the first electrode grid line 400 and the substrate 100 can more efficiently conduct the current inside the cell. On the other hand, smaller second electrode grid lines 500 are disposed between adjacent first electrode grid lines 400 to reduce the light-shielding area of the grid lines, thereby further improving the optical absorption of the solar cell, which is beneficial to improving the battery's performance. Photoelectric conversion efficiency.

In one embodiment, continuing to refer to FIG. 1 , the light-receiving surface 110 of the substrate 100 has a textured structure, and the backlight surface 120 of the substrate 100 has a smooth surface structure. It can be understood that the textured structure on the front can minimize the light reflectivity of the cell and increase the optical absorption of the cell, thus increasing the short-circuit current to enhance the photoelectric conversion efficiency, and is conducive to increasing the contact between the electrode grid line and the substrate. area to improve contact resistance. Optionally, anisotropic etching may be produced on the light-receiving surface 110 of the substrate 100 through a chemical reaction to form a dense texture of micropyramidal pyramid structure. The backlight surface 120 of the substrate 100 is a polished surface, that is, the backlight surface 120 of the substrate is polished to form a complete plane to enhance the internal reflection of light, thereby reducing the surface recombination rate of carriers.

In one embodiment, as shown in FIG. 3 , a plurality of first electrode grid lines 400 extend along the first direction X and are arranged at equal intervals in sequence.

Wherein, the first electrode grid lines 400 are parallel to each other in the second direction Y, and the plurality of first electrode grid lines 400 are arranged in a straight line with equal spacing along the first direction X, so that the current of each first electrode grid line 400 is collected. More uniform, it is beneficial to increase the output current of the battery.

In one embodiment, as shown in FIG. 1 , the first electrode gate line 400 includes a first doping layer 410 and a metal electrode layer 420 . The first doping layer 410 is located in the first open film region of the front passivation structure 300 The upper surface layer of the light-receiving surface 110 of the substrate 100 is injected. The doping type of the first doping layer 410 is the same as that of the substrate 100 . The metal electrode layer 420 is stacked on a side of the first doping layer 410 away from the substrate 100 . On the side surface, the metal electrode layer 420 forms ohmic contact with the substrate 100 through the first doping layer 410, and two adjacent metal electrode layers 420 in the first direction form an electrical connection through the second electrode gate line; wherein, the first The doping concentration of the doping layer 410 is greater than that of the substrate 100 .

The substrate 100 contains doping elements. The doping elements may be N-type elements or P-type elements. Alternatively, the N-type elements may be any one of phosphorus, arsenic or antimony, and the P-type elements may be Any element among boron, gallium or aluminum, that is, when the doping element inside the substrate 100 is an N-type element, the substrate 100 is an N-type substrate, and when the doping element inside the substrate 100 is P When using a P-type element, the substrate 100 is a P-type substrate. This embodiment takes the substrate 100 as a P-type substrate as an example for illustration.

Further, the first doped layer 410 is implanted in the first film-opening region and into the upper surface layer of the light-receiving surface 110 of the substrate 100 . Its doping type is the same as that of the substrate 100 , and its doping concentration is greater than that of the substrate 100 . The doping concentration forms a high-low junction structure between the first doping layer 410 and the substrate 100. The high-low junction refers to establishing a concentration gradient of the same impurity between the substrate 100 and the metal electrode layer 420, That is, a P-P+ or N-N+ high-low junction is prepared. For example, in this embodiment, the first doping layer 410 includes aluminum ions or aluminum ions doped with P-type elements (such as boron). During the printing process of the electrode grid lines , aluminum paste or boron-containing aluminum paste can be used for sintering in the first film opening area. During the sintering process, the aluminum paste forms an aluminum-silicon alloy (first doped layer) at the contact interface with the substrate 100 silicon wafer, that is, on the lining A first doping layer 410 is formed on the upper surface layer of the light-receiving surface 110 of the base 100 to form a P-P+ high-low junction with the substrate 100 . Further, a metal material is deposited on a side surface of the first doped layer 410 facing away from the substrate 100 to form a metal electrode layer 420 , whereby the metal electrode layer 420 can form electrical contact with the substrate 100 through the first doped layer 410 .

Among them, for the metal electrode layer 420, the first doped layer 410 that the metal electrode layer 420 contacts is a heavily doped region, and the first doped layer 410 can reduce the threshold voltage between the metal electrode layer 420 and the substrate 100. , making it easier for carriers to be transported to the first doping layer 410 for collection by the metal electrode layer 420 , thereby enhancing the conductivity between the metal electrode layer 420 and the substrate 100 . The non-metallic region of the light-receiving surface 110 of the substrate 100 is a lightly doped region, which can reduce the recombination rate on the surface and increase the minority carrier lifetime, thereby improving the conversion efficiency. Therefore, by forming a high-low junction on the light-receiving surface 110 of the substrate 100 to suppress the migration of photo-generated electrons to the backside for recombination, the effective collection of carriers can be improved, the long-wavelength response of the solar cell can be improved, and the short-circuit current and open-circuit voltage can be increased.

Further, a second electrode grid line is formed on a side surface of the front passivation structure 300 away from the substrate 100 to connect two adjacent metal electrode layers 420 , that is, the front electrode on the light-receiving surface includes a first film-opening area. The metal electrode layer 420 and the second electrode gate line are connected, and the two parts are connected. Optionally, the metal electrode layer 420 and the second electrode grid line may be formed using processes such as screen printing or laser transfer.

In one embodiment, the second electrode grid line is a metal silver grid line. It can be understood that the particle size of silver powder is generally around 1μm, while the particle size of aluminum powder is as high as 10μm. If the silver electrode is printed as the front electrode, the use of silver material will increase the cost of the device. If aluminum paste is used for printing to form the front aluminum electrode , due to its excessive particle size, its actual printing width is much higher than that of existing silver electrodes, which increases the blocking area on the front of the cell and causes greater optical loss of the cell. Therefore, in this embodiment, a laser grooving process is used to create a plurality of first film-opening areas on the front of the cell, and aluminum paste is provided in the first film-opening areas. After annealing and sintering, the first film-opening areas are formed on the upper surface of the light-receiving surface of the substrate. The doped layer forms a high-low junction on the front side to increase efficiency and conduct current inside the cell. Further, aluminum paste or boron-containing aluminum paste is used to print a metal electrode layer on the surface of the first doped layer, and silver paste is printed between adjacent metal electrode layers to form metal silver grid lines, giving full play to the silver powder particle size. The advantage is small, so that thinner second electrode grid lines can be printed to reduce grid line occlusion and increase the optical absorption of the cell.

It should be noted that the second electrode grid line can also be a low-temperature silver paste with a sintering temperature lower than 300°C. If a traditional high-temperature sintering silver paste with a sintering temperature close to that of traditional aluminum paste is used, the gap between the high-temperature silver paste and the aluminum paste will be The glass frits will react with each other, destroying the stability of the paste and causing greater losses to the substrate. Therefore, using low-temperature silver paste to form a metal silver grid line for the second electrode grid line can enhance the stability of the device.

Optionally, the size (width) of the metal electrode layer in the second direction may be between 40 μm and 80 μm, and the size (width) of the second electrode gate line in the second direction may be between 15 and 35 μm.

In this embodiment, the second electrode grid line in the non-opening area is set as a metal silver grid line, taking full advantage of the small particle size of silver powder to reduce the printing width of the grid line, thereby further improving the optical absorption of the cell sheet and increasing the battery life. The photoelectric conversion efficiency of the chip.

In one embodiment, continuing to refer to FIG. 1 , the front passivation structure 300 includes a passivation layer 310 and an anti-reflection layer 320 . The passivation layer 310 is located on the light-receiving surface 110 of the substrate 100 , and the anti-reflection layer 320 is located on the passivation layer 310 On the side away from the substrate 100 , the first film-opening area is opened on the anti-reflection layer 320 and penetrates the anti-reflection layer 320 and the passivation layer 310 in sequence.

Among them, the passivation layer 310 is used to reduce the recombination rate of carriers at the interface and provide a good field effect passivation effect for the light-receiving surface 110 of the substrate 100, thereby improving the operating performance and stability of the battery. The passivation layer 310 is located in the passivation layer 310. The anti-reflection layer 320 on the surface is used to reduce or eliminate the reflected light on the surface of the solar cell substrate 100 to increase the amount of light transmission, thereby improving the photoelectric conversion efficiency of the solar cell. Optionally, the material of the passivation layer 310 may be any one or at least two of a silicon-containing layer, aluminum oxide, silicon oxide, silicon nitride, and silicon oxynitride, and the material of the antireflection layer 320 may be silicon oxide, Any of silicon oxynitride.

Further, local grooves are made on the surface of the front passivation structure 300 through a laser film opening process to partially open the anti-reflection layer 320 and the passivation layer 310. The grooved part is called the first film opening area and the first electrode grid line. 400 is located in the first open film area to form ohmic contact with the substrate 100 .

In one embodiment, the ratio between the area of the first open film region of the front passivation structure and the area of the light-receiving surface of the substrate is lower than a preset threshold.

Alternatively, the preset threshold may be 0.7%, that is, the ratio of the area of the first open film area to the light-receiving surface of the substrate is lower than 0.7%. It can be understood that in order to open the contact channel between the first electrode grid line and the substrate, a high-energy laser is usually used to ablate the front passivation structure. Since the laser film deposition uses a light spot with a Gaussian beam, it is easy to damage. The substrate under the film layer in the light spot area further affects the conversion efficiency. Therefore, the plurality of first open film areas provided in this embodiment are arranged at intervals in the first direction of the light-receiving surface, that is, only on the first electrode grid line Regional film opening. Compared with the existing technology of linear uninterrupted film opening in the first direction, the first film opening areas arranged at intervals and with a lower area ratio in this embodiment can effectively avoid laser film opening on the substrate. damage.

In one embodiment, as shown in FIG. 1 , the back electrode structure 200 includes a back passivation structure 210 and a back electrode 220 . The back passivation structure 210 is located on the backlight surface 120 of the substrate 100 , and the back electrode 220 is located on the back passivation structure. 210 is away from the side of the substrate 100 .

Among them, the back passivation structure 210 forms a PN junction with the substrate 100, which can effectively avoid optical losses caused by forming a highly doped emitter on the light-receiving surface 110 of the substrate 100, and is used to provide good surface passivation and reduce metal contact. The composite current increases the open circuit voltage and circuit current of the cell, which is beneficial to optimizing the performance of the solar cell. The back electrode 220 is in contact with the back passivation structure 210 to form electrical contact, which is used to collect and aggregate the current of the battery. Optionally, the material of the back electrode 220 may be one or more of silver, copper, nickel, and aluminum.

In one embodiment, as shown in FIG. 1 , the backside passivation structure 210 includes a tunnel oxide layer 211 and a second doped layer 212 . The tunnel oxide layer 211 is located on the backlight surface 120 of the substrate 100 . The layer 212 is located on a side surface of the tunnel oxide layer 211 away from the substrate 100 . The doping type of the second doped layer 212 is different from the doping type of the substrate 100 . The back electrode 220 is located on a side of the second doped layer 212 away from the substrate 100 and is in contact with the second doped layer 212 .

Among them, the tunnel oxide layer 211 and the second doped layer 212 are sequentially stacked on the backlight surface 120 of the substrate 100 in a direction away from the substrate 100. The doping type of the second doped layer 212 is the same as the doping type of the substrate 100. On the contrary, for example, when the substrate 100 is a P-type substrate, the doping element type of the second doping layer 212 is N-type, whereby the second doping layer 212 forms a PN junction with the substrate 100 and tunnels through the oxide layer 211 can make the majority carriers tunnel into the second doped layer 212. The majority carriers are laterally transported in the second doped layer 212 to be collected by the back electrode 220. The tunnel oxide layer 211 can reduce the The interface state density between the substrate 100 and the second doped layer 212 reduces the recombination of minority carriers and holes, which can effectively reduce the contact recombination current between the back electrode 220 and the second doped layer 212 . Optionally, the tunnel oxide layer 211 can be formed by thermal oxidation. The material of the tunnel oxide layer 211 can be a dielectric material, such as silicon oxide, magnesium fluoride, silicon oxide, amorphous silicon, polysilicon, silicon carbide, At least one of silicon nitride, silicon oxynitride, aluminum oxide or titanium oxide, the material of the second doping layer 212 may be a polycrystalline silicon (poly-Si) material containing a doping source, and the doping of the doping source The element type is opposite to the doping element type of the substrate 100 .

In one of the embodiments, as shown in FIG. 1 , the backside passivation structure 210 also includes a dielectric layer 213 . The dielectric layer 213 is located on a side surface of the second doped layer 212 away from the substrate 100 . The dielectric layer 213 is provided with a plurality of The second film opening area. There are multiple back electrodes 220 , and each back electrode 200 is located in a second open film area to contact the second doped layer 212 . Each back electrode 220 is arranged in a gate line shape along the first direction.

Among them, the dielectric layer 213 is stacked on the surface of the second doped layer 212 for protection. The dielectric layer 213 can reduce the recombination rate of the metal area generated by the contact between the back electrode 220 and the substrate 100, thereby improving the conversion efficiency. Optionally, the dielectric layer 213 can be a single layer or a stacked layer structure, and the material of the dielectric layer 213 can be any one or at least two of a silicon-containing layer, an aluminum oxide layer, silicon oxide, silicon nitride, and silicon oxynitride. , this embodiment takes the dielectric layer 213 as a stacked structure as an example (as shown in Figure 1). Specifically, the dielectric layer 213 may include a back passivation layer and a back anti-reflection layer that are sequentially stacked in a direction away from the substrate 100. The material of the back passivation layer can be any one or at least two of the silicon-containing layer, aluminum oxide, silicon oxide, silicon nitride, and silicon oxynitride. The material of the back antireflection layer can be any of silicon oxide and silicon oxynitride. any kind.

Furthermore, the plurality of back electrodes 220 are thin gate lines extending straightly along the first direction. A plurality of second film opening areas extending along the first direction can be formed on the surface of the dielectric layer 213 through a laser film forming process. Each back electrode 220 corresponds to a second open film region, thereby forming a structure in which the back electrode 220 penetrates the dielectric layer 213 to form electrical contact with the second doped layer 212, so that the carriers in the battery can be led out by the back electrode.

Based on this, the present application provides a first doped layer on the light-receiving surface of the substrate to form a high-low junction with the substrate, and at the same time, a back passivation structure is provided on the backlight surface of the substrate to form a PN junction with the substrate, thereby suppressing photogenerated carriers. The recombination caused by migration to the back side improves the photoelectric conversion efficiency of the solar cell.

This application provides an exemplary preparation method of the above-mentioned solar cell, wherein the solar cell is explained by taking a P-type passivated contact solar cell as an example. The specific preparation method is as follows:

Provide P-type silicon substrate, clean and polish the P-type silicon substrate to remove dirt on the surface of the silicon substrate, and then use it for subsequent processes;

A tunnel oxide layer is formed on the backlight surface of the P-type silicon substrate through a thermal oxidation process;

A polysilicon (poly-Si) layer is formed on the side surface of the tunnel oxide layer away from the substrate through the PEALD/LPCVD/PECVD deposition process, and then the polysilicon layer is phosphorus expanded using normal pressure diffusion or low pressure diffusion to form the second doped layer. Doped layer, so that the second doped layer and the P-type silicon substrate form a backside PN junction; or, directly use the PEALD/LPCVD/PECVD deposition process to form a phosphorus-doped polysilicon layer on the surface of the side of the tunnel oxide layer away from the substrate ;

De-plating the light-receiving surface of the P-type silicon substrate to remove the polysilicon layer deposited on the front side to prevent leakage;

Texturing cleaning is used to form a textured structure on the light-receiving surface, thereby increasing optical absorption. The cleaning function is to remove the chemical liquid and metal ions remaining on the surface of the P-type silicon substrate due to texturing;

Through the PECVD, PEALD or ALD process, a passivation layer and an anti-reflection film are sequentially deposited on the light-receiving surface of the P-type silicon substrate to form a front passivation structure, and a dielectric layer is also deposited on the backlight surface, for example, a back passivation layer and a back anti-reflection film are sequentially deposited. anti-membrane;

Laser film-opening is performed on the surface of the front passivation structure of the light-receiving surface to form a plurality of first film-opening areas. The aluminum paste is sintered into each first film-opening area to form a first doped layer, and the first doped layer is formed on the surface of the first doped layer. Aluminum metal or boron-containing aluminum metal is formed as a metal electrode layer by screen printing or laser transfer, and two adjacent metal electrode layers are connected by printing metal silver grid lines; for the medium on the backlight surface The layer is laser-opened to expose the surface of the second doped layer to form a plurality of second open-film regions, and silver metal is deposited on each second open-film region to form a back electrode;

Through changes in temperature field and optional (electric intensity field, light intensity field), it drives the movement of hydrogen ions in the front passivation structure and the back dielectric layer, making it possible to passivate defects in solar cells and increase the photoelectric conversion of the cells. efficiency.

This application also provides a photovoltaic module. The photovoltaic module includes a battery string, and the battery string is connected by the solar cells provided in any of the above embodiments.

The photovoltaic module also includes an encapsulation layer and a cover plate. The encapsulation layer is used to cover the surface of the battery string, and the cover plate is used to cover the surface of the encapsulation layer away from the battery string. The solar cells are electrically connected in the form of a whole piece or multiple slices to form multiple battery strings, and the multiple battery strings are electrically connected in series and/or in parallel. Specifically, in some embodiments, multiple battery strings may be electrically connected through conductive charges. The encapsulation layer covers the surface of the solar cell. For example, the encapsulating layer may be an organic encapsulating adhesive film such as an ethylene-vinyl acetate copolymer adhesive film, a polyethylene octene co-elastomer adhesive film, or a polyethylene terephthalate adhesive film. The cover plate can be a glass cover plate, a plastic cover plate, or other cover plate with a light-transmitting function.

In the description of this specification, reference to the terms "some embodiments," "other embodiments," "ideal embodiments," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included herein. In at least one embodiment or example of the application. In this specification, schematic descriptions of the above terms do not necessarily refer to the same embodiment or example.

The technical features of the above embodiments can be combined in any way. To simplify the description, not all possible combinations of the technical features of the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, all possible combinations should be used. It is considered to be within the scope of this manual.

The above-described embodiments only express several implementation modes of the present application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent application. It should be noted that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all fall within the protection scope of the present application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims (10)

1. A solar cell, comprising:

a substrate having a light receiving surface and a light back surface arranged opposite to each other;

a back electrode structure located on a backlight surface of the substrate;

the front passivation structure is positioned on the light receiving surface of the substrate;

the first electrode grid lines are positioned in the first film opening area of the front passivation structure to form ohmic contact with the substrate, and are arranged at intervals along the first direction;

the plurality of second electrode grid lines are positioned on one side of the front passivation structure, which is away from the substrate, and are used for connecting two adjacent first electrode grid lines in the first direction;

and in the second direction, the size of the second electrode grid line is smaller than that of the first electrode grid line, and the first direction is perpendicular to the second direction.

2. The solar cell of claim 1, wherein the plurality of first electrode grid lines extend along the first direction and are sequentially arranged at equal intervals.

3. The solar cell of claim 1, wherein the first electrode grid line comprises:

the first doping layer is positioned in a first film opening area of the front passivation structure so as to be injected into the upper surface layer of the light receiving surface of the substrate, and the doping type of the first doping layer is the same as that of the substrate;

a metal electrode layer laminated on one side surface of the first doped layer away from the substrate, wherein the metal electrode layer forms ohmic contact with the substrate through the first doped layer, and two adjacent metal electrode layers in the first direction form electrical connection through the second electrode grid line;

wherein the doping concentration of the first doping layer is greater than the doping concentration of the substrate.

4. A solar cell according to any one of claims 1 to 3, wherein the front side passivation structure comprises:

the passivation layer is positioned on the light-receiving surface of the substrate;

the anti-reflection layer is positioned on one side of the passivation layer away from the substrate;

the first film opening area is arranged on the anti-reflection layer and penetrates through the anti-reflection layer and the passivation layer in sequence.

5. A solar cell according to any one of claims 1 to 3, wherein the second electrode grid is a metallic silver grid.

6. A solar cell according to any one of claims 1 to 3, wherein the ratio between the area of the first open film region of the front side passivation structure and the area of the light receiving surface of the substrate is below a preset threshold.

7. The solar cell of claim 1, wherein the back electrode structure comprises:

a back passivation structure located on the back light surface of the substrate;

and the back electrode is positioned on one side of the back passivation structure away from the substrate.

8. The solar cell of claim 7, wherein the backside passivation structure comprises:

the tunneling oxide layer is positioned on the backlight surface of the substrate;

the second doping layer is positioned on the surface of one side, far away from the substrate, of the tunneling oxide layer, and the doping type of the second doping layer is different from that of the substrate;

the back electrode is located on one side of the second doped layer away from the substrate and is in contact with the second doped layer.

9. The solar cell of claim 8, wherein the back passivation structure further comprises:

the dielectric layer is positioned on the surface of one side of the second doping layer far away from the substrate, and is provided with a plurality of second film opening areas;

the number of the back electrodes is a plurality, each back electrode is correspondingly positioned in one second film opening area to be in contact with the second doping layer, and the back electrodes are arranged in a grid line shape along the first direction.

10. A photovoltaic module comprising a solar cell according to any one of claims 1 to 9.