A passivated contact solar cell and photovoltaic module

Abstract

The present application provides a passivated contact solar cell and a photovoltaic module, wherein the passivated contact solar cell comprises a silicon substrate, and the backlight surface of the silicon substrate comprises a first region and a third region arranged at intervals; in the first region, a dielectric layer, a first doping layer and a first passivation layer are sequentially arranged on the backlight surface of the silicon substrate, and the dielectric layer and the first doping layer form a passivated contact structure in the first region; in the third region, a first passivation layer is arranged on the backlight surface of the silicon substrate; a second region is arranged between the first region and the third region, and the second region has a step structure, and the number of steps in the step structure is at least two, which can reduce the optical loss of the passivated contact solar cell, thereby improving the photoelectric conversion efficiency of the solar cell.

Description

Technical Field

[0001] The present application relates to the field of solar cells, and in particular to a passivated contact solar cell and a photovoltaic module. Background Art

[0002] Passivated contact solar cells are a type of solar cells based on selective carrier transport and have broad application prospects.

[0003] The current passivated contact solar cell has a passivated contact structure mainly composed of a dielectric layer and a doping layer (also known as a Poly layer). However, the doping layer itself has the ability to extinct, which leads to an increase in the optical loss of the passivated contact solar cell, affects the short-circuit current of the passivated contact solar cell, and further affects its photoelectric conversion efficiency. How to reduce the optical loss of the passivated contact solar cell to increase its short-circuit current, thereby improving the photoelectric conversion efficiency of the solar cell, has become a technical problem that needs to be solved urgently. Summary of the invention

[0004] In order to solve the above technical problems, the present application discloses a passivated contact solar cell and a photovoltaic module to reduce the optical loss of the passivated contact solar cell, thereby improving the short-circuit current and photoelectric conversion efficiency of the passivated contact solar cell.

[0005] In a first aspect, the present application provides a passivated contact solar cell, comprising:

[0006] A silicon substrate, wherein the backlight surface of the silicon substrate comprises a first region and a third region which are arranged at intervals;

[0007] In the first region, a dielectric layer, a first doping layer and a first passivation layer are sequentially arranged on the backlight surface of the silicon substrate, and the dielectric layer and the first doping layer form a passivation contact structure in the first region;

[0008] In the third region, the backlight surface of the silicon substrate is provided with the first passivation layer;

[0009] A second area is provided between the first area and the third area. The second area has a step structure. The number of steps in the step structure is at least two.

[0010] In some embodiments of the present application, the step structure includes a first step and a second step, the first step includes an intersecting first sub-surface and a second sub-surface, and the second step includes an intersecting third sub-surface and a fourth sub-surface.

[0011] In some embodiments of the present application, the distance between the first sub-surface and the third sub-surface is H1, 0.05 μm≤H1≤0.2 μm.

[0012] In some embodiments of the present application, the distance between the third sub-surface and the first plane is H2, 0.5 μm≤H2≤8 μm, and the first plane is: a side of the first passivation layer in the third region facing away from the silicon substrate.

[0013] In some embodiments of the present application, the angle between the third sub-surface and the fourth sub-surface is α, and α≥90°.

[0014] In some embodiments of the present application, the second sub-surface intersects with the third sub-surface.

[0015] In some embodiments of the present application, a width of the third sub-surface is w1, 0.01 μm≤w1≤5 μm.

[0016] In some embodiments of the present application, the step structure further includes a texture structure, and the texture structure is recessed relative to the third sub-surface and / or the fourth sub-surface.

[0017] In some embodiments of the present application, the texture structure is located on the silicon substrate corresponding to the third sub-surface;

[0018] and / or, the texture structure is located on the silicon substrate corresponding to the fourth sub-surface;

[0019] And / or, the texture structure is located on the silicon substrate corresponding to the first junction, and the first junction is the junction between the third sub-surface and the fourth sub-surface.

[0020] In some embodiments of the present application, the average width of the texture structure is w2, 0.5 μm≤w2≤10 μm.

[0021] In some embodiments of the present application, the first region is provided with a first electrode, and the first electrode passes through the first passivation layer and contacts the first doping layer.

[0022] In a second aspect, the present application provides a photovoltaic module, wherein the photovoltaic module comprises the solar cell as described in the first aspect.

[0023] Compared with the prior art, this application has at least the following beneficial effects:

[0024] The present application provides a passivated contact solar cell and a photovoltaic module, wherein the passivated contact solar cell comprises a silicon substrate, the backlight surface of the silicon substrate comprises a first region and a third region arranged at intervals; in the first region, a dielectric layer, a first doping layer and a first passivation layer are sequentially arranged on the backlight surface of the silicon substrate, and the dielectric layer and the first doping layer form a passivated contact structure in the first region; in the third region, a first passivation layer is arranged on the backlight surface of the silicon substrate; a second region is arranged between the first region and the third region, and the second region has a step structure, and the number of steps in the step structure is at least two. The second region of the present application constitutes a transition region between the first region and the third region, and the second region has at least two step structures, and these step structures can adjust the angle of the incident light, so that the light can enter the interior of the solar cell more easily, thereby improving the utilization rate of the incident light, reducing the optical loss of the solar cell, and increasing its short-circuit current, thereby improving the photoelectric conversion efficiency of the solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0026] Figure 1 This is a schematic diagram of the structure of a solar cell in one embodiment of the present application;

[0027] Figure 2 for Figure 1 A partial enlarged schematic diagram of the area framed by the dotted line in the middle;

[0028] Figure 3 This is a schematic diagram of the structure of a step structure in one embodiment of the present application;

[0029] Figure 4 This is a schematic structural diagram of a step structure in another embodiment of the present application;

[0030] Figure 5 This is a schematic structural diagram of a step structure in another embodiment of the present application;

[0031] Figure 6 This is a schematic diagram of the structure of a texture structure in one embodiment of the present application;

[0032] Figure 7 This is a schematic diagram of the structure of a solar cell in another embodiment of the present application;

[0033] Figure 8 This is a scanning electron microscope (SEM) image of the backlight surface of the solar cell in Example 1 of the present application.

[0034] Description of reference numerals:

[0035] 1-silicon substrate, 2-dielectric layer, 3-first doped layer, 4-first passivation layer, 5-step structure, 7-texture structure, 8-second doped layer, 9-second passivation layer, 10-anti-reflection layer, 11-first region, 12-second region, 13-third region, 51-first step, 52-second step, 61-first electrode, 62-second electrode, 101-backlight surface, 102-light receiving surface, 511-first sub-surface, 512-second sub-surface, 521-third sub-surface, 522-fourth sub-surface. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0037] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "vertical", "horizontal", "lateral", "longitudinal" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings. These terms are mainly used to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0038] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those of ordinary skill in the art, the specific meanings of these terms in this application can be understood according to specific circumstances.

[0039] In addition, the terms "installed", "set", "provided with", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection, or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0040] In addition, the terms "first", "second", etc. are mainly used to distinguish different devices, elements or components (the specific types and structures may be the same or different), and are not used to indicate or imply the relative importance and quantity of the indicated devices, elements or components. Unless otherwise specified, "plurality" means two or more.

[0041] The technical solution of the present application will be further described below in conjunction with embodiments and drawings.

[0042] In a first aspect, the present application provides a passivated contact solar cell, such as Figure 1 As shown, the passivated contact solar cell includes a silicon substrate 1, and the backlight surface 101 of the silicon substrate 1 includes a first area 11 and a third area 13 arranged at intervals; in the first area 11, the backlight surface 101 of the silicon substrate 1 is provided with a dielectric layer 2, a first doping layer 3 and a first passivation layer 4 in sequence, and the dielectric layer 2 and the first doping layer 3 form a passivation contact structure in the first area; in the third area 13, the backlight surface 101 of the silicon substrate 1 is also provided with a first passivation layer 4; a second area 12 is provided between the first area 11 and the third area 13, and the second area 12 has a step structure 5, and the number of steps in the step structure 5 is at least two, for example, the number of steps is 2, 3, 4 or 5.

[0043] In this application, reference Figure 1 , the first region 11 refers to: the region corresponding to the orthographic projection of the first electrode 61 on the surface of the silicon substrate 1 on the backlight surface 101 of the silicon substrate 1; the second region 12 refers to: the region with a step structure on the backlight surface 101 of the silicon substrate 1; the third region 13 refers to: the region other than the first region 11 and the second region 12 on the backlight surface 101 of the silicon substrate 1. The second region of the present application has at least two step structures, which can adjust the angle of the incident light, making it easier for the light to enter the interior of the solar cell, thereby improving the utilization rate of the incident light, reducing the optical loss of the solar cell, and increasing its short-circuit current, thereby improving the photoelectric conversion efficiency of the solar cell. In some embodiments, the second region may include a dielectric layer and a first doping layer; in other embodiments, the second region may not include a dielectric layer and a first doping layer.

[0044] In an optional embodiment, reference Figure 2 , Figure 2 for Figure 1A partial enlarged schematic diagram of the area in the middle dotted circle frame, the step structure 5 includes a first step 51 and a second step 52, the first step 51 includes an intersecting first sub-surface 511 and a second sub-surface 512, the second step 52 includes an intersecting third sub-surface 521 and a fourth sub-surface 522, the number of steps in the step structure of the present application is two, the first step serves as a height transition for the second step, the second step has no or only a portion of the first doped layer below, under the joint action of the first step and the second step, the absorption of light by the first doped layer is reduced, the photon utilization rate is improved, and the optical loss of the solar cell is reduced.

[0045] In an optional embodiment, reference Figure 2 , the distance between the first sub-surface 511 and the third sub-surface 521 is H1, 0.05μm≤H1≤0.2μm. For example, H1 is 0.05μm, 0.1μm, 0.15μm or 0.2μm. By adjusting H1 within the above range, photon absorption can be optimized, and by adjusting the film structure and film thickness of the first passivation layer, the absorption effect of light at the first step can be improved.

[0046] In an optional embodiment, reference Figure 2 , the distance between the third sub-surface 521 and the first plane is H2, 0.5μm≤H2≤8μm. For example, H2 is 0.5μm, 1μm, 3μm, 5μm or 8μm. The first plane refers to: the side of the first passivation layer 4 in the third region 13 away from the silicon substrate 1. By adjusting H2 within the above range, the passivation performance of the first passivation layer at the second step can be optimized, and the absorption effect of light at the second step can be improved.

[0047] In an optional embodiment, reference Figure 2 , the angle between the third sub-surface 521 and the fourth sub-surface 522 is α, α≥90°. For example, α is 90°, 100°, 110°, 120° or 135°. Observed along the length extension direction of the first electrode 61, the fourth sub-surface may be a surface perpendicular to the third sub-surface; or, the fourth sub-surface may be an inclined surface inclined relative to the third sub-surface. By adjusting α within the above range, the incident light angle at the second step can be optimized, thereby improving the utilization rate of the incident light.

[0048] In an optional embodiment, reference Figure 2 , the second sub-surface 512 intersects with the third sub-surface 521. In this way, the first step 51 and the second step 52 can be connected to form the step structure of the present application, which is beneficial to reduce the optical loss of the passivation contact solar cell.

[0049] In an optional embodiment, reference Figure 2, the width of the third sub-surface 521 is w1, 0.01 μm ≤ w1 ≤ 5 μm. For example, w1 is 0.01 μm, 0.1 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm or 5 μm. By adjusting w1 within the above range, the incident light angle at the third sub-surface can be optimized, thereby improving the utilization rate of the incident light.

[0050] In an optional embodiment, reference Figure 2 , the step structure also includes a texture structure 7, and the texture structure 7 is recessed relative to the third sub-surface 521 and / or the fourth sub-surface 522. In the present application, the texture structure can be a pit-like structure that is recessed downward relative to the third sub-surface and / or the fourth sub-surface. In one example, the texture structure can be a pit in the shape of an inverted pyramid, wherein the top of the inverted pyramid is away from the third sub-surface and / or the fourth sub-surface. Among the above-mentioned multiple texture structures, there may be one texture structure in the shape of an inverted pyramid, or there may be multiple texture structures in the shape of an inverted pyramid, and the present application has no special restrictions. Since the above-mentioned texture structure can utilize the principle of light trapping to reduce the reflection of incident light, thereby increasing the amount of light absorption, it can improve the utilization rate of light by the passivated contact solar cell, which is beneficial to the improvement of the photoelectric conversion efficiency.

[0051] It should be noted that the step structure of the present application may include a texture structure or may not include a texture structure, which is reasonable.

[0052] The present application has no particular restrictions on the method for forming the texture structure, as long as a downwardly concave structure can be formed on the third sub-surface and / or the fourth sub-surface. For example, the backlight surface of the solar cell having the first doping layer can be firstly laser etched, and then the texture structure can be formed by a wet alkaline etching process; of course, the texture structure can also be formed by other methods, which are not particularly limited in the present application.

[0053] In one embodiment, reference Figure 3 , the texture structure 7 is located on the silicon substrate 1 corresponding to the third sub-surface 521, that is, the texture structure 7 is recessed downward relative to the third sub-surface 521; in another embodiment, referring to Figure 2 , the texture structure 7 is located on the silicon substrate 1 corresponding to the fourth sub-surface 522, that is, the texture structure 7 is recessed downward relative to the fourth sub-surface 522; in another embodiment, referring to Figure 4 , the junction of the third sub-surface 521 and the fourth sub-surface 522 is the first junction, and the texture structure 7 is located on the silicon substrate corresponding to the first junction, that is, the texture structure 7 is concave downward relative to the first junction; in another embodiment, reference Figure 5, the texture structure 7 is located on the silicon substrate 1 corresponding to the third sub-surface 521, and on the silicon substrate 1 corresponding to the fourth sub-surface 522, and on the silicon substrate 1 corresponding to the first junction. The step structure of the present application has the above texture structure, which can use the light trapping principle to reduce the reflection of light incident on the third sub-surface and / or the fourth sub-surface, thereby increasing the amount of light absorption and improving the utilization rate of light by the passivated contact solar cell.

[0054] In one embodiment, the average width of the texture structure is w2, 0.5 μm ≤ w2 ≤ 10 μm. For example, w2 is 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm or 10 μm. The width of the texture structure refers to the maximum length of the line connecting any two points at the bottom of the texture structure, for example, see Figure 6 When the texture structure is in the shape of an inverted pyramid, the width of the texture structure can be the length of the line connecting point A and point B on its bottom surface, where point A and point B can be any two vertices at the bottom of the texture structure. In this application, the average width of the texture structure refers to randomly selecting 10 texture structures from the step structure and then calculating the average width of these texture structures. By adjusting w2 within the above range, the angle of the incident light can be adjusted, thereby improving the utilization rate of the incident light.

[0055] In one embodiment, reference Figure 1 The first region 11 is provided with a first electrode 61 , and the first electrode 61 contacts the first doping layer 3 through the first passivation layer 4 , thereby forming an ohmic contact.

[0056] In one embodiment, the material of the first passivation layer is selected from at least one of aluminum oxide, silicon nitride and silicon oxynitride. The first passivation layer formed by the above materials is conducive to fully passivating the interface of the solar cell, thereby improving the performance of the solar cell.

[0057] Furthermore, in one embodiment, reference Figure 7 The light-receiving surface 102 of the passivated contact solar cell of the present application is also provided with a second doping layer 8, a second passivation layer 9, an anti-reflection layer 10 and a second electrode 62 in sequence, and the light-receiving surface 102 of the silicon substrate has a velvet structure. In order to better absorb solar energy, the light-receiving surface of the silicon substrate of the present application has a velvet structure. For example, the velvet structure can adopt a pyramid-shaped velvet structure. Through the velvet structure, a higher surface area can be provided for the solar cell while reducing the reflection and diffusion of light. The present application has no special restrictions on the preparation method of the velvet structure, as long as the purpose of the present application can be achieved. For example, it can be prepared by the existing magnetron sputtering method.

[0058] In a second aspect, the present application provides a photovoltaic module, wherein the photovoltaic module comprises the solar cell as described in the first aspect.

[0059] The present application also provides a photovoltaic module, which is used to convert received light energy into electrical energy and transmit it to an external load. The photovoltaic module includes: at least one battery string, which is formed by connecting a plurality of the above-mentioned solar cells; a packaging film, which is used to cover the surface of the battery string; and a cover plate, which is used to cover the surface of the packaging film away from the battery string.

[0060] The material of the dielectric layer of the present application may include a variety of dielectric materials, such as at least one of silicon oxide, magnesium fluoride, amorphous silicon, polycrystalline silicon, silicon carbide, silicon nitride, silicon oxynitride, aluminum oxide or titanium oxide. Specifically, the dielectric layer may be composed of a silicon oxide layer containing silicon oxide. This is because the silicon oxide layer has excellent passivation properties, can minimize the recombination loss of minority carriers on the surface of the semiconductor substrate, and is a film with excellent durability for subsequent high-temperature processes. In order to better provide interface passivation for the substrate, the thickness of the dielectric layer may be 0.1nm~5nm. For example, the thickness of the dielectric layer may be 0.1nm, 0.5nm, 1nm, 1.5nm, 2nm, 3nm, 4nm, 5nm, etc., however, the present application is not limited thereto, and the thickness of the dielectric layer may have various values. The dielectric layer, as a barrier for electrons and holes, may be combined with a polycrystalline silicon layer to prevent minority carriers from passing through. The dielectric layer may also have a pinhole channel effect, allowing the carriers in the solar cell to move freely, and selective passage of majority carriers is generated by heavily doped polycrystalline silicon, which is conducive to reducing the recombination loss of minority carriers. In addition, the dielectric layer may serve as a diffusion barrier to prevent dopants of the doped polysilicon layer from diffusing into the semiconductor substrate.

[0061] The present application has no particular restrictions on the preparation method of the passivated contact solar cell. Exemplarily, the passivated contact solar cell can be prepared by the following method:

[0062] Step A, providing an initial structure of a solar cell, the initial structure of the solar cell comprising a silicon substrate, the backlight surface of the silicon substrate having a first doping layer and a dielectric layer, and the light-receiving surface of the silicon substrate having a second doping layer;

[0063] Step B, performing patterning on the backlight surface of the silicon substrate to form a first region, a second region and a third region on the backlight surface of the silicon substrate;

[0064] Step C, forming a first passivation layer on the backlight surface of the patterned silicon substrate by a plasma enhanced chemical vapor deposition (PECVD) device, forming a second passivation layer on the surface of the second doped layer by an atomic layer deposition (ALD) device, and forming an anti-reflection layer on the surface of the second passivation layer by a PECVD device;

[0065] Step D: prepare the first electrode and the second electrode on the backlight side and the light-receiving side of the initial structure of the solar cell respectively.

[0066] In step A of the present application, the silicon substrate may be of the first conductivity type, the doping element of the second doping layer may have the second conductivity type, one of the first conductivity type and the second conductivity type may be N-type and the other may be P-type. For example, when the first conductivity type is N-type, the second conductivity type may be P-type; when the first conductivity type is P-type, the second conductivity type may be N-type. The silicon substrate may be a textured silicon substrate, the thickness of which may be 100 μm to 200 μm, and the present application does not make any specific limitation as long as it can meet the purpose of the present application.

[0067] In step B of the present application, in an optional embodiment, a structure having the above-mentioned first region, second region and third region can be formed on the backlight surface of the silicon substrate by laser etching combined with a wet etching process, and the specific process includes:

[0068] a. Use plasma enhanced chemical vapor deposition (PECVD) equipment to deposit a dielectric layer, a phosphorus-doped amorphous silicon layer and a silicon oxide mask layer on the backlight side of the silicon substrate in sequence, and the process temperature is controlled at 400℃~500℃;

[0069] b. Use tubular high-temperature equipment to perform high-temperature annealing at 900°C to 980°C to convert the amorphous silicon in the phosphorus-doped amorphous silicon layer into polycrystalline silicon, activate the phosphorus atoms therein, form the first doping layer, and obtain a semi-finished solar cell;

[0070] c. Use green picosecond laser, and set the laser energy density to 150 mJ / cm 2 ~400 mJ / cm 2 , scanning a predetermined graphic area (such as a third area) of the backlight surface of a semi-finished solar cell product, so that the silicon oxide mask layer in the corresponding area is peeled off or denatured;

[0071] d. Use chain HF equipment to remove the oxide layer on the front and edge of the solar cell, and then perform trench wet alkaline etching, using 0.5wt%~5wt% alkaline solution to etch the first doping layer and dielectric layer in the laser processing area to form a graphic structure with a first area, a second area and a third area.

[0072] In another optional embodiment, a structure having the first region, the second region and the third region can be formed on the backlight surface of the silicon substrate by a mask method combined with a wet etching process, and the specific process includes:

[0073] a', using PECVD equipment to sequentially deposit a dielectric layer and a phosphorus-doped amorphous silicon layer on the backlight side of the silicon substrate, with the process temperature controlled at 400°C~500°C;

[0074] b', using a tubular high temperature device to perform high temperature annealing at 900°C to 950°C, so as to convert the amorphous silicon in the phosphorus-doped amorphous silicon layer into polycrystalline silicon, activate the phosphorus atoms therein, form the first doping layer, and obtain a semi-finished solar cell;

[0075] c', using a chain coating method to apply an alkali-resistant mask slurry to the surface of a semi-finished solar cell product to form an alkali-resistant mask layer, and then using a laser to scan a predetermined graphic area (such as a third area of ​​the design) on the backlight surface of the semi-finished solar cell product to cause the alkali-resistant mask layer in the corresponding area to be distorted or denatured, thereby exposing the film layer originally under the alkali-resistant mask layer;

[0076] d', RCA cleaning: Use chain HF equipment to remove the oxide layer on the front and edge of the solar cell, and then perform trench wet alkaline etching, using 0.5 wt%~2 wt% alkaline solution for 200s~400s to etch the first doping layer and dielectric layer in the exposed area to form a graphic structure with a first area, a second area and a third area.

[0077] In step C of the present application, the first passivation layer can be formed based on the PECVD process, the second passivation layer can be formed based on the ALD process, and the anti-reflection layer can be formed based on the PECVD process. The first passivation layer can be an aluminum oxide layer, and the first passivation layer plays a passivation role; the anti-reflection layer can be a silicon oxynitride layer, and the anti-reflection layer plays an anti-reflection role; in addition, the second passivation layer can be prepared on the backlight side of the initial structure of the solar cell, and the second passivation layer can be a silicon oxynitride layer, which plays a passivation role.

[0078] The present application has no particular restrictions on the thickness of each functional layer, as long as the purpose of the present application can be achieved. For example, the thickness of the first passivation layer is 70 nm to 120 nm, the thickness of the second passivation layer is 1 nm to 5 nm, and the thickness of the anti-reflection layer is 60 nm to 100 nm.

[0079] In step D of the present application, the first electrode and the second electrode can be respectively prepared on the backlight surface and the light-receiving surface of the initial structure of the solar cell by screen printing.

[0080] The present application has no particular restrictions on the method of regulating H1 and H2. For example, H1 and H2 generally increase with the increase of laser power during laser etching, and increase with the increase of corrosion intensity during wet etching. The corrosion intensity generally increases with the increase of etching time, the increase of etching process temperature, and the increase of alkali solution concentration. Based on this, H1 and H2 can be regulated by regulating laser power, wet etching process, etc.; the present application has no particular restrictions on the method of regulating W1. For example, W1 generally increases with the increase of corrosion intensity during wet etching. Based on this, W1 can be regulated by regulating wet etching related process parameters; the present application has no particular restrictions on the method of regulating W2. For example, W2 generally increases with the increase of corrosion intensity during wet etching. Based on this, W2 can be regulated by regulating wet etching related process parameters.

[0081] The present application has no special restrictions on the laser used for laser etching, as long as the purpose of the present application can be achieved. The laser-related parameters of the present application can be: the laser type is at least one of nanosecond laser, picosecond laser, and femtosecond laser; the light type is any one of infrared laser, visible light laser, and ultraviolet laser; the laser energy density is 30 mJ / cm 2 ~3000 mJ / cm 2 , wavelength is 300nm~1000nm, and the laser spot shape can be circular or square.

[0082] This application has no particular restrictions on the alkali solution for wet etching, as long as the purpose of this application can be achieved. For example, the alkali solution can be a NaOH solution or a KOH solution, and the concentration of the alkali solution is 0.5 wt%~5 wt%. In addition, the process temperature of the alkali etching of this application can be 60℃~80℃, and the etching time can be 200s~1000s, as long as a texture structure can be formed on the sub-surface of the step structure.

[0083] Example

[0084] The passivated contact solar cell and photovoltaic module of the present application will be further described below in conjunction with more specific embodiments.

[0085] Example 1

[0086] <Providing the initial structure of solar cells>

[0087] A textured solar cell initial structure is provided, the solar cell initial structure includes a silicon substrate, the backlight side of the silicon substrate has a first doping layer, a dielectric layer and a silicon oxide mask layer, and the light-receiving side of the silicon substrate has a second doping layer. The silicon substrate is an N-type silicon wafer with a thickness of 125 μm, the doping element of the first doping layer is phosphorus (P), and the doping element of the second doping layer is boron (B);

[0088] <Graphical Processing>

[0089] A green picosecond laser is used to scan the predetermined graphic area of ​​the backlight surface of the semi-finished solar cell, so that the silicon oxide mask layer in the corresponding area is distorted or denatured, and the first doping layer and dielectric layer in the corresponding area are removed to initially form a step structure; a chain HF device is used to remove the oxide layer on the front and edge of the solar cell, and then a groove wet alkaline etching is performed to form a graphic structure with a first area, a second area and a third area;

[0090] <Preparation of the First Passivation Layer>

[0091] Depositing a first passivation layer with a thickness of 80 nm on the backlight surface of the patterned silicon substrate by PECVD equipment;

[0092] <Preparation of the Second Passivation Layer and Anti-reflection Layer>

[0093] A second passivation layer with a thickness of 5 nm is deposited on the side of the second doped layer away from the silicon substrate by ALD equipment, and then an anti-reflection layer with a thickness of 80 nm is deposited on the surface of the second passivation layer by PECVD equipment.

[0094] <Preparation of Electrode>

[0095] The first electrode and the second electrode are respectively prepared on the backlight side and the light-receiving side of the initial structure of the solar cell by screen printing to form Figure 7 The solar cell structure shown.

[0096] Embodiment 2 to Embodiment 6

[0097] Except that in <Patterning Processing>, the process parameters such as laser power and alkali concentration of wet etching are adjusted to control H1, H2, W1, and W2 according to Table 1, the rest is the same as Example 1.

[0098] Table 1 Relevant preparation parameters of Example 1 to Example 6

[0099]

[0100] Open circuit voltage, short circuit current, fill factor test:

[0101] The current (I)-voltage (V) of the solar cells of each embodiment and comparative example was measured using an IV tester (model: MX-MPVC-A20) to obtain the open circuit voltage, short circuit current density and fill factor of the solar cells.

[0102] Photoelectric conversion efficiency test:

[0103] The current (I)-voltage (V) of the solar cells of each embodiment and comparative example was measured using an IV tester (model: MX-MPVC-A20) to obtain the photoelectric conversion efficiency (Eta) of the solar cells.

[0104] Table 2 Performance data of Examples 1 to 6

[0105]

[0106] It can be seen from Examples 1 to 6 that the solar cell of the present application has a relatively high open circuit voltage, short circuit current density, fill factor and photoelectric conversion efficiency. It can be seen that the solar cell having the structure of the present application exhibits good photoelectric conversion performance.

[0107] Figure 8 This is a SEM image of the backlight surface of the solar cell of Example 1 of the present application, Figure 8 It can be seen that the backlight surface of the solar cell has a first step 51 and a second step 52 , wherein the first step 51 includes a first sub-surface 511 and a second sub-surface 512 intersecting each other, and the second step 52 includes a third sub-surface 521 and a fourth sub-surface 522 intersecting each other.

[0108] The above is a detailed introduction to a passivated contact solar cell and photovoltaic module disclosed in the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solutions and core inventions of the embodiments of the present application. At the same time, for general technicians in this field, according to the ideas of the present application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A passivated contact solar cell, characterized in that: include: A silicon substrate, wherein a backlight surface of the silicon substrate comprises a first region and a third region that are arranged at intervals; In the first region, a dielectric layer, a first doping layer and a first passivation layer are sequentially arranged on the backlight surface of the silicon substrate, and the dielectric layer and the first doping layer form a passivation contact structure in the first region; In the third region, the backlight surface of the silicon substrate is provided with the first passivation layer; A second area is provided between the first area and the third area, the second area has a step structure, and the number of steps in the step structure is at least two; The step structure includes a first step and a second step, the first step includes a first sub-surface and a second sub-surface intersecting each other, and the second step includes a third sub-surface and a fourth sub-surface intersecting each other; The first area is: on the backlight side of the silicon substrate, the area corresponding to the orthographic projection of the first electrode on the surface of the silicon substrate; the second area is: on the backlight side of the silicon substrate, the area having the step structure; the third area is: on the backlight side of the silicon substrate, the area excluding the first area and the second area.

2. The passivated contact solar cell according to claim 1, characterized in that: A distance between the first sub-surface and the third sub-surface is H1, and 0.05 μm≤H1≤0.2 μm.

3. The passivated contact solar cell according to claim 1, characterized in that: The distance between the third sub-surface and the first plane is H2, 0.5 μm≤H2≤8 μm, and the first plane is: a side of the first passivation layer in the third region facing away from the silicon substrate.

4. The passivated contact solar cell according to claim 1, characterized in that: The included angle between the third sub-surface and the fourth sub-surface is α, and α≥90°.

5. The passivated contact solar cell according to claim 1, characterized in that: The second sub-surface intersects the third sub-surface.

6. The passivated contact solar cell according to claim 1, characterized in that: The width of the third sub-surface is w1, 0.01 μm≤w1≤5 μm.

7. The passivated contact solar cell according to claim 1, characterized in that: The step structure further includes a texture structure, and the texture structure is recessed relative to the third sub-surface and / or the fourth sub-surface.

8. The passivated contact solar cell according to claim 7, characterized in that: The texture structure is located on the silicon substrate corresponding to the third sub-surface; and / or, the texture structure is located on the silicon substrate corresponding to the fourth sub-surface; And / or, the texture structure is located on the silicon substrate corresponding to the first junction, and the first junction is the junction between the third sub-surface and the fourth sub-surface.

9. The passivated contact solar cell according to claim 7, characterized in that: The average width of the texture structure is w2, 0.5 μm≤w2≤10 μm.

10. The passivated contact solar cell according to any one of claims 1 to 9, characterized in that: The first region is provided with a first electrode, and the first electrode passes through the first passivation layer and contacts the first doping layer.

11. A photovoltaic module, characterized in that: The photovoltaic module comprises the passivated contact solar cell according to any one of claims 1 to 10.

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