Passivation contact structure, solar cell and photovoltaic module

Abstract

The utility model relates to the technical field of solar cells, in particular to a passivation contact structure, a solar cell and a photovoltaic module. The passivation contact structure comprises: a dielectric layer, wherein the thickness of the dielectric layer is 1.20-1.40 nm; the doped layer is arranged on the dielectric layer and comprises a first doped polycrystalline silicon layer, a silicon oxide layer and a second doped polycrystalline silicon layer which are sequentially arranged in the direction away from the dielectric layer, the thickness of the first doped polycrystalline silicon layer ranges from 20 nm to 40 nm, the thickness of the silicon oxide layer ranges from 1.0 nm to 2.0 nm, and the thickness of the second doped polycrystalline silicon layer ranges from 80 nm to 100 nm. The passivation contact structure can effectively relieve the film explosion phenomenon of the solar cell and improve the performance of the solar cell.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of solar cell technology, and in particular to a passivation contact structure, a solar cell and a photovoltaic module. Background Art

[0002] Passivated contact solar cells are one of the most promising solar cells in the field of solar cells.

[0003] Passivated contact solar cells usually include a dielectric layer and a doped polysilicon layer. Limited by the manufacturing process of the doped polysilicon layer, the doped polysilicon layer is easily prone to film explosion due to the residual hydrogen in the film layer and the escape of hydrogen in the subsequent annealing process, which damages the passivation performance of the passivated contact solar cell, and reduces the open circuit voltage, filling performance and photoelectric conversion efficiency. Utility Model Content

[0004] The purpose of the embodiments of the present application is to provide a passivation contact structure, a solar cell and a photovoltaic module to effectively alleviate the film explosion phenomenon of the solar cell and improve the performance of the solar cell.

[0005] To achieve the above objectives, the present application provides the following technical solutions:

[0006] In a first aspect, an embodiment of the present application provides a passivation contact structure, the passivation contact structure comprising:

[0007] A dielectric layer, wherein the thickness of the dielectric layer is 1.20 nm to 1.40 nm;

[0008] A doped layer is provided on the dielectric layer, the doped layer comprising a first doped polysilicon layer, a silicon oxide layer and a second doped polysilicon layer arranged in sequence along a direction away from the dielectric layer; wherein the thickness of the first doped polysilicon layer is 20nm to 40nm, the thickness of the silicon oxide layer is 1.0nm to 2.0nm, and the thickness of the second doped polysilicon layer is 80nm to 100nm.

[0009] Furthermore, both the first doped polysilicon layer and the second doped polysilicon layer are doped polysilicon layers doped with semiconductor conductive elements, and the doping concentration of the semiconductor conductive elements in the second doped polysilicon layer is higher than the doping concentration of the semiconductor conductive elements in the first doped polysilicon layer.

[0010] Furthermore, the doping concentration of the semiconductor conductive element in the first doped polysilicon layer is 1×10 16 cm -3 ~9×10 18 cm -3 The doping concentration of the semiconductor element in the second doped polysilicon layer is 1×1020 cm -3 ~9×10 21 cm -3 The square resistance of the second doped polysilicon layer is 16Ω·sq -1 ~26Ω·sq -1 .

[0011] Furthermore, the second doped polysilicon layer includes a first doped sublayer arranged close to the silicon oxide layer and a second doped sublayer arranged away from the silicon oxide layer, and the doping concentration of the semiconductor conductive element in the second doped sublayer is higher than the doping concentration of the semiconductor conductive element in the first doped sublayer.

[0012] Furthermore, the thickness of the first doped sublayer is 25 nm to 45 nm, and the doping concentration of the semiconductor conductive element in the first doped sublayer is 3×10 17 cm -3 ~7×10 19 cm -3 The thickness of the second doped sublayer is 35 nm to 55 nm, and the doping concentration of the semiconductor conductive element in the second doped sublayer is 5×10 18 cm -3 ~9×10 21 cm -3 .

[0013] Furthermore, the first doped polysilicon layer and the second doped polysilicon layer are both doped polysilicon layers doped with the semiconductor conductive element and carbon element, and the doping concentration of the carbon element in any of the doped polysilicon layers is 1×10 15 cm -3 ~9×10 18 cm -3 .

[0014] In a second aspect, an embodiment of the present application provides a solar cell, comprising a silicon substrate and the passivation contact structure described in the first aspect, wherein the dielectric layer is disposed close to the silicon substrate, and the doping layer is disposed away from the silicon substrate.

[0015] Furthermore, a diffusion layer is provided between the silicon substrate and the dielectric layer, and the diffusion layer, the first doped polysilicon layer, and the second doped polysilicon layer all have semiconductor conductive elements of the same conductive type, and the concentration of the semiconductor conductive elements in the diffusion layer is 1×10 17 cm -3 ~6×10 18 cm -3 .

[0016] Furthermore, the doping layer is a whole layer structure, and the position of the doping layer corresponds to both the metallized region of the solar cell and the non-metallized region of the solar cell.

[0017] In a third aspect, an embodiment of the present application provides a photovoltaic module, wherein the photovoltaic module includes the passivation contact structure as described in the first aspect and / or the solar cell as described in the second aspect.

[0018] Compared with the prior art, the beneficial effects of the embodiments of the present application are:

[0019] The passivation contact structure provided in the embodiment of the present application can effectively alleviate the film explosion phenomenon and optimize the passivation performance. The passivation contact structure includes a dielectric layer and a first doped polysilicon layer, a silicon oxide layer, and a second doped polysilicon layer sequentially arranged on the dielectric layer. By providing a silicon oxide layer between the first doped polysilicon layer and the second doped polysilicon layer, and controlling the thickness of each layer of the dielectric layer and the doped layer, on the one hand, the silicon oxide layer can be used as a barrier layer to prevent the hydrogen generated in the first doped polysilicon layer and the second doped polysilicon from mixing, thereby slowing down the concentrated escape of a large amount of hydrogen, and working together with the dielectric layer to slow down the occurrence of the film explosion phenomenon; on the other hand, the present application arranges the first doped polysilicon layer adjacent to the dielectric layer, and arranges a silicon oxide layer between the first doped polysilicon layer and the second doped polysilicon layer. The presence of the silicon oxide layer prevents the semiconductor conductive elements from entering the first doped polysilicon layer through the second doped polysilicon layer, so that a small amount but not a large amount of semiconductor conductive elements enters the dielectric layer from the first doped polysilicon layer, and then enters the silicon substrate. This low concentration of doping can reduce the recombination of minority carriers at the interface, increase the passivation effect, and is beneficial to improving the performance of passivated contact solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments of the present application. 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 creative work.

[0021] Figure 1 It is a schematic diagram of the structure of the solar cell of the embodiment of the present application;

[0022] Figure 2 It is a TEM image of the dielectric layer in the solar cell of the embodiment of the present application.

[0023] Figure 3 It is a schematic diagram of the structure of another solar cell according to an embodiment of the present application.

[0024] Reference numerals:

[0025] 1. Passivation contact structure; 11. Dielectric layer; 12. Doping layer; 121. First doped polysilicon layer; 122. Silicon oxide layer; 123. Second doped polysilicon layer; 1231. First doped sublayer; 1232. Second doped sublayer; 2. Silicon substrate; 3. PN junction; 4. First functional layer; 41. First passivation layer; 42. First anti-reflection layer; 5. Second functional layer; 6. First electrode; 7. Second electrode. DETAILED DESCRIPTION

[0026] 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.

[0027] In the present application, the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] The technical solution provided in this application will be further described below in conjunction with embodiments and drawings.

[0032] Passivated contact solar cells are considered to be one of the most promising and commercially valuable solar cells in the photovoltaic cell field due to their excellent passivation performance, high photoelectric conversion efficiency and low production cost. However, further improvement of their efficiency still requires solving problems such as film explosion.

[0033] The film explosion problem of passivated contact solar cells is related to the large-scale escape of hydrogen. When the doped polysilicon film is deposited by plasma enhanced chemical vapor deposition (PECVD) equipment, a large amount of hydrogen enters the polysilicon film layer. During the subsequent crystallization annealing process, hydrogen accumulates and stays inside the film in the form of hydrogen. When the temperature rises to a certain level, the high temperature will stimulate its rapid escape and eventually lead to the occurrence of film explosion. Although the degree of film explosion can be appropriately adjusted by adjusting the PECVD process parameters, the improvement effect is limited. Based on the analysis of the above problems, a passivated contact structure of a solar cell is provided in the embodiment of the present application, which can effectively suppress the large-scale escape of hydrogen, alleviate the occurrence of film explosion, and optimize the passivation performance.

[0034] In a first aspect, an embodiment of the present application provides a passivation contact structure for use in a solar cell. Figure 1 This is a schematic diagram of the structure of the solar cell in the embodiment of the present application. Figure 1 The solar cell has a passivation contact structure 1, which includes a dielectric layer 11 and a doped layer 12 arranged on the dielectric layer 11, and the doped layer 12 includes a first doped polysilicon layer 121, a silicon oxide layer 122 and a second doped polysilicon layer 123 arranged in sequence along a direction away from the dielectric layer 11.

[0035] The material of the dielectric layer 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. The dielectric layer, as a barrier to electrons and holes, may be combined with the 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 be used as a diffusion barrier to prevent the dopant of the doped polycrystalline silicon layer from diffusing into the semiconductor substrate.

[0036] like Figure 2As shown, in the embodiment of the present application, the dielectric layer 11 has good density. The dense dielectric layer 11 can effectively inhibit hydrogen from penetrating the dielectric layer 11 during the formation of subsequent film layers such as the first doped polysilicon layer 121 and the second doped polysilicon layer 123, thereby alleviating the occurrence of film explosion and preventing the passivation performance of the solar cell from being affected by the film explosion.

[0037] Moreover, in the embodiment of the present application, a silicon oxide layer 122 is provided between the first doped polysilicon layer 121 and the second doped polysilicon layer 123, the first doped polysilicon layer 121 is provided adjacent to the dielectric layer 11, and the thickness of each layer of the dielectric layer 11 and the doped layer 12 is controlled. On the one hand, the silicon oxide layer 122 can be used as a barrier layer to prevent the hydrogen generated in the first doped polysilicon layer 121 and the second doped polysilicon layer 123 from mixing, thereby slowing down the concentrated escape of a large amount of hydrogen, and working together with the dielectric layer 11 to slow down the occurrence of the film explosion phenomenon; on the other hand, the presence of the silicon oxide layer 122 prevents the semiconductor conductive elements from entering the first doped polysilicon layer 121 through the second doped polysilicon layer 123, so that a small amount of semiconductor conductive elements, rather than a large amount, enter the dielectric layer 11 from the first doped polysilicon layer 121, and then enter the silicon substrate 2. This low concentration of doping can reduce the recombination of minority carriers at the interface, increase the passivation effect, and is conducive to improving the performance of the passivated contact solar cell.

[0038] In the embodiment of the present application, the thickness of the dielectric layer 11 is 1.2nm to 1.4nm; the thickness of the first doped polysilicon layer 121 is 20nm to 40nm; the thickness of the silicon oxide layer 122 is 1.0nm to 2.0nm; and the thickness of the second doped polysilicon layer 123 is 80nm to 100nm.

[0039] The thickness of the dielectric layer 11 is controlled within the above range, which can provide good passivation effect and carrier transport effect, ensuring that the dielectric layer 11 can reduce the recombination of electrons and holes, and can be transmitted through the thinner dielectric layer 11 through carrier transport mechanisms such as quantum tunneling effect. Exemplarily, the thickness of the dielectric layer 11 is 1.20nm, 1.25nm, 1.30nm, 1.35nm, 1.40nm, etc.

[0040] In the embodiment of the present application, the thickness of the silicon oxide layer 122 is set to 1.0nm to 2.0nm. The silicon oxide layer 122 of this thickness can be used as a barrier layer to prevent the hydrogen gas escaping from the second doped polysilicon layer 123 from mixing with the hydrogen gas escaping from the first doped polysilicon layer 121, and can also reduce the influence of the excessive thickness of the silicon oxide layer on the conductive properties of the passivation contact structure. Exemplarily, the thickness of the silicon oxide layer 122 is 1.0nm, 1.2nm, 1.3nm, 1.6nm, 1.7nm, 2.0nm, etc.

[0041] The first doped polysilicon layer 121, the silicon oxide layer 122, and the second doped polysilicon layer 123 constitute the doped layer 12. The thickness of each layer is controlled, and the thickness of the doped layer can be controlled. A thinner doped layer may result in insufficient light absorption and lower photoelectric conversion efficiency. On the premise of ensuring photoelectric performance, the thinner the thickness of the doped layer, the lower the manufacturing cost. Therefore, in order to balance performance and cost, in the embodiment of the present application, the thickness of the first doped polysilicon layer 121 is 20nm to 40nm, and the thickness of the second doped polysilicon layer 123 is 80nm to 100nm.

[0042] Further, the first doped polysilicon layer 121 and the second doped polysilicon layer 123 are both doped polysilicon layers doped with semiconductor conductive elements, and the doping concentration of the semiconductor conductive elements in the second doped polysilicon layer is higher than the doping concentration of the semiconductor conductive elements in the first doped polysilicon layer. The doped semiconductor conductive elements may be N-type conductive elements or P-type conductive elements. For example, the N-type conductive element may be phosphorus, and the P-type conductive element may be boron.

[0043] In the embodiment of the present application, the doping concentration of the semiconductor conductive element in the first doped polysilicon layer 121 is 1×10 16 cm -3 ~9×10 18 cm -3 The doping concentration of the semiconductor conductive element in the second doped polysilicon layer 123 is 1×10 20 cm -3 ~9×10 21 cm -3 The square resistance of the second doped polysilicon layer 123 is 16

[0044] Ω·sq -1 ~26Ω·sq -1 . Appropriate doping concentration can balance the carrier concentration, provide good conductivity, and improve the photoelectric conversion efficiency. The doping concentration of the semiconductor conductive element in the second doped polysilicon layer 123 away from the silicon substrate 2 is higher than that in the first doped polysilicon layer 121 close to the silicon substrate 2, which can improve the passivation effect of the metal contact position, while reducing the contact resistance between the metal electrode and silicon, and promoting the improvement of the opening voltage and filling performance of the battery cell. The square resistance can reflect the surface doping concentration of the semiconductor conductive element. The higher the surface doping concentration, the lower the square resistance. Conversely, the lower the surface doping concentration, the higher the square resistance. For example, the doping concentration of the semiconductor conductive element in the first doped polysilicon layer 121 is 1×10 16 cm -3 , 5×10 16 cm -3 ,7×10 16 cm -3 , 1×10 17 cm-3 , 3×10 17 cm -3 , 6×10 17 cm -3 ,9×10 17 cm -3 , 4×10 18 cm -3 ,9×10 18 cm -3 For example, the doping concentration of the semiconductor conductive element in the second doped polysilicon layer 123 is 1×10 20 cm -3 , 3×10 20 cm -3 , 4×10 20 cm -3 , 8×10 20 cm -3 , 10×10 20 cm -3 , 3×10 21 cm -3 , 5×10 21 cm -3 , 6×10 21 cm -3 ,9×10 21 cm -3 For example, the square resistance of the second doped polysilicon layer 123 is 16Ω·sq -1 , 17Ω·sq -1 , 19Ω·sq -1 , 21Ω·sq -1 , 23Ω·sq -1 , 26Ω·sq -1 wait.

[0045] It is understandable that in the doped polysilicon layer, the doping concentration of the semiconductor conductive element increases layer by layer until the surface concentration is the highest. The high surface concentration can improve the passivation effect of the metal contact position, while reducing the contact resistance between the metal electrode and the silicon, and promoting the improvement of the opening voltage and filling performance of the battery cell. In the embodiment of the present application, the thickness of the first doped polysilicon layer 121 is less than that of the second doped polysilicon layer 123. On the one hand, it can ensure that a moderate amount of semiconductor conductive elements enter the silicon substrate instead of a large amount. If a large amount of semiconductor conductive elements penetrate the tunneling layer into the silicon substrate, it will destroy the passivation effect of the tunneling layer and increase the recombination rate at the interface, reducing the open circuit voltage and fill factor. On the other hand, the second doped polysilicon layer 123 is thicker than the first doped polysilicon layer 121 to ensure a high surface doping concentration. The high surface doping concentration can reduce the surface square resistance and promote the improvement of the fill factor.

[0046] Figure 3FIG. 1 is a schematic diagram of the structure of another solar cell in the embodiment of the present application. Figure 3 As shown, the second doped polysilicon layer 123 includes a first doped sublayer 1231 arranged close to the silicon oxide layer and a second doped sublayer 1232 arranged away from the silicon oxide layer, and the doping concentration of the semiconductor conductive element in the second doped sublayer 1232 is higher than the doping concentration of the semiconductor conductive element in the first doped sublayer 1231.

[0047] As an embodiment, the thickness of the first doped sublayer 1231 is 25 nm to 45 nm, and the doping concentration of the semiconductor conductive element in the first doped sublayer 1231 is 3×10 17 cm -3 ~7×10 19 cm -3 The thickness of the second doped sublayer 1232 is 35 nm to 55 nm, and the doping concentration of the semiconductor conductive element in the second doped sublayer 1232 is 5×10 18 cm -3 ~9×10 21 cm -3 .

[0048] The second doped polysilicon layer 123 is set to be a first doped sublayer 1231 and a second doped sublayer 1232. More doped polysilicon layers can form a finer semiconductor conductive element doping concentration gradient. The semiconductor conductive element concentration in the doped polysilicon layer close to the silicon substrate is lower and the concentration is higher on the side away from the silicon substrate, further improving the passivation effect of the metal contact position while reducing the contact resistance between the metal electrode and silicon.

[0049] The second doped polysilicon layer includes a first doped sublayer and a second doped sublayer, but is not limited to the first doped sublayer and the second doped sublayer. For example, the second doped polysilicon layer may also include a third doped sublayer, and the third doped sublayer is arranged on a side of the second doped sublayer away from the first doped sublayer. It should be noted that in the embodiment of the present application, the first doped sublayer 1231 and the second doped sublayer 1232 are arranged adjacent to each other, and a silicon oxide layer is not arranged between the first doped sublayer 1231 and the second doped sublayer 1232, so that the semiconductor conductive element can form a uniform doping concentration gradient between the first doped sublayer 1231 and the second doped sublayer 1232, which is beneficial to the improvement of the performance of the solar cell.

[0050] Furthermore, the first doped polysilicon layer 121 and the second doped polysilicon layer 123 are both doped polysilicon layers doped with semiconductor conductive elements and carbon elements, and the doping concentration of carbon elements in any doped polysilicon layer is 1×10 15 cm -3 ~9×10 18 cm -3 .

[0051] Taking the semiconductor conductive element as phosphorus as an example, the first doped polysilicon layer 121 and the second doped polysilicon layer 123 are both phosphorus doped polysilicon layers, and carbon is doped in the phosphorus doped polysilicon layer. The performance of the first doped polysilicon layer 121 and the second doped polysilicon layer 123 is optimized by co-doping carbon and phosphorus. A large number of hydrogen atoms in the doped polysilicon layer can form CH bonds with carbon atoms. The bonding force of the CH bond is stronger than that of the Si-H bond. The CH bond is not easy to break during the high-temperature crystallization annealing process, which slows down the diffusion and escape of hydrogen and avoids the occurrence of film explosion caused by the large-scale release of hydrogen in a short time. At the same time, the introduction of carbon can also increase the optical band gap of the polysilicon layer, improve the transmittance of light in the polysilicon layer, reduce parasitic absorption, increase the utilization of light, and promote the improvement of the short-circuit current of the battery cell. Exemplarily, the doping concentration of carbon is 1×10 15 cm -3 , 3×10 15 cm -3 , 8×10 15 cm -3 , 4×10 16 cm -3 ,9×10 16 cm -3 , 2×10 17 cm -3 , 1×10 18 cm -3 ,9×10 18 cm -3 .

[0052] It is understandable that the dielectric layer 11 and the doping layer 12 in the embodiment of the present application can be film layers deposited by low pressure chemical vapor deposition (LPCVD) equipment or plasma enhanced chemical vapor deposition (PECVD, Plasma-Enhanced Chemical Vapor Deposition) equipment. It is preferably deposited by PECVD equipment. Although hydrogen elements are easily introduced into the first doped polysilicon layer 121 and the second doped polysilicon layer 123 in the doping layer deposited by the PECVD equipment, since the present application adopts a dense dielectric layer 11 and introduces a silicon oxide layer 122 between the first doped polysilicon layer 121 and the second doped polysilicon layer 123, it can well solve the problem of film explosion generated during the subsequent crystallization annealing process. It can be seen that the technical solution of the embodiment of the present application is particularly suitable for solving the problem of film explosion caused by the deposition of dielectric layers and doping layers by PECVD equipment. In addition, during the crystallization annealing process, by adopting a partial increase in the annealing temperature and appropriately increasing the annealing temperature on this basis, the doping performance of the semiconductor conductive element can be improved while effectively suppressing the intensification of hydrogen escape caused by rapid temperature increase, increasing the surface doping concentration of the semiconductor conductive element, and promoting the performance of solar cells.

[0053] In a second aspect, the present application provides a solar cell, such as Figure 1 As shown, the solar cell comprises:

[0054] Silicon substrate 2;

[0055] A PN junction 3 and a first functional layer 4 are sequentially arranged on the light-receiving surface of the silicon substrate 2;

[0056] A passivation contact structure 1 and a second functional layer 5 are sequentially arranged on the backlight surface of a silicon substrate 2; wherein the dielectric layer 11 in the passivation contact structure 1 is arranged close to the silicon substrate 2, and the doping layer 12 is arranged away from the silicon substrate 2;

[0057] A first electrode 6, penetrating the first functional layer 4 and making ohmic contact with the PN junction;

[0058] The second electrode 7 penetrates the second functional layer 5 and is in ohmic contact with the doping layer 12 .

[0059] Further, the first functional layer 4 includes a first passivation layer and / or a first anti-reflection layer. For example, in one embodiment, the first functional layer includes a first passivation layer 41 and a first anti-reflection layer 42 sequentially arranged on the PN junction 3. Among them, the first passivation layer 41 may include one or more sub-layers, and the first passivation layer 41 may be an aluminum oxide layer. The first anti-reflection layer 42 may include one or more sub-layers, and the first anti-reflection layer 42 may be a composite layer of one or more of a silicon nitride layer, a silicon oxynitride layer, or a silicon oxide layer.

[0060] Further, the second functional layer 5 includes a second passivation layer and / or a second anti-reflection layer. In one embodiment, the second functional layer 5 is a second passivation layer. The second passivation layer may include one or more sub-layers, and the second passivation layer may be a silicon nitride layer. The second anti-reflection layer may include one or more sub-layers.

[0061] It should be noted that the conductivity type of the silicon substrate can be either N-type or P-type, and this is not limited in this application. The silicon substrate has a light-receiving surface and a backlight surface, and the passivation contact structure can be arranged on the light-receiving surface of the silicon substrate or on the backlight surface of the silicon substrate, and this is not limited in this application.

[0062] In an optional embodiment, the silicon substrate is an N-type silicon substrate, and the passivation contact structure is located on the backlight side of the N-type silicon substrate and has a different conductivity type from the N-type silicon substrate. The passivation contact structure includes a dielectric layer, a P-type first doped polysilicon layer, a silicon oxide layer, and a P-type second doped polysilicon layer that are sequentially away from the silicon substrate. In another optional embodiment, the silicon substrate is an N-type silicon substrate, and the passivation contact structure is located on the light-receiving side of the N-type silicon substrate, including a dielectric layer, an N-type first doped polysilicon layer, a silicon oxide layer, and an N-type second doped polysilicon layer that are sequentially away from the silicon substrate.

[0063] Furthermore, a diffusion layer is provided between the silicon substrate and the dielectric layer, and the diffusion layer, the first doped polysilicon layer, and the second doped polysilicon layer all have semiconductor conductive elements of the same conductive type, and the concentration of the semiconductor conductive elements in the diffusion layer is 1×10 17 cm -3 ~6×10 18 cm -3 .

[0064] During the diffusion of the doping elements in the first doped polysilicon layer to the dielectric layer, although most of the doping elements are blocked by the dielectric layer, a small amount of doping elements still pass through the dielectric layer into the silicon substrate to form a diffusion layer. Furthermore, a proper amount of semiconductor conductive elements penetrate the dielectric layer into the silicon substrate layer to reduce the recombination of minority carriers at the interface and increase the passivation effect. In the present application, the thickness of the dielectric layer with better density is set to 1.2nm to 1.4nm, which can prevent hydrogen from penetrating the dielectric layer and allow a proper amount of semiconductor conductive elements to pass through the dielectric layer into the silicon substrate.

[0065] Furthermore, a functional layer is disposed outside the doping layer in a direction away from the silicon substrate, and the functional layer includes a silicon nitride layer or a silicon oxynitride layer or a composite layer of several of them, which is not limited in the present application.

[0066] It should be noted that other functional film layer structures may also be included in the solar cell of the present application. For example, the solar cell of the present application may also include a PN junction disposed on a silicon substrate, and one of the PN junction and the passivation contact structure is disposed on the light-receiving surface of the silicon substrate, and the other structure is disposed on the backlight surface of the silicon substrate. For another example, the solar cell also includes a passivation layer and an anti-reflection layer disposed on the side of the PN junction away from the silicon substrate. For another example, the solar cell may also include a first electrode and a second electrode that are in ohmic contact with the PN junction and the doped layer, respectively. The above-mentioned functional film layer structures may be conventionally arranged, and the present application does not impose any restrictions on them.

[0067] Furthermore, the doped layer 12 is a whole layer structure, that is, the position of the doped layer 12 corresponds to both the metallized area of ​​the solar cell and the non-metallized area of ​​the solar cell. The metallized area of ​​the solar cell refers to a specific area formed on the surface of the solar cell for collecting and conducting current, usually a part that has been metallized or metal electrode wired; the area that has not been metallized is the non-metallic area. In other words, the doped layer 12 covers the corresponding position of the entire silicon substrate, that is, the first doped polysilicon layer 121, the silicon oxide layer 122, and the second doped polysilicon layer 123 all cover the corresponding position of the entire silicon substrate 2, such as Figure 1 As shown. As a preferred embodiment, the thickness of each layer in the doped layer 12 is relatively uniform. Specifically, the first doped polysilicon layer 121, the silicon oxide layer 122, the second doped polysilicon layer 123 located in the metal contact area and the first doped polysilicon layer 121, the silicon oxide layer 122, the second doped polysilicon layer 123 located in the non-metal contact area have substantially the same thickness. It can be understood that uneven thickness will lead to local stress concentration, and local stress concentration will make the film layer easy to break when impacted by hydrogen, and a relatively uniform thickness improves the structural stability of each film layer.

[0068] In a third aspect, an embodiment of the present application provides a photovoltaic module, which includes the passivation contact structure as described in the first aspect and / or the solar cell as described in the second aspect.

[0069] Example 1

[0070] This embodiment provides a solar cell, including:

[0071] N-type silicon substrate;

[0072] A PN junction, a first passivation layer and a first anti-reflection layer are sequentially arranged on the light-receiving surface of the N-type silicon substrate;

[0073] A passivation contact structure and a second passivation layer are sequentially arranged on the backlight surface of an N-type silicon substrate; wherein, along the direction away from the silicon substrate, the passivation contact structure sequentially includes a dielectric layer and a doping layer, and the doping layer sequentially includes a first doped polysilicon layer doped with phosphorus and carbon elements, a silicon oxide layer, and a second doped polysilicon layer doped with phosphorus and carbon elements; wherein, the dielectric layer is a silicon oxide layer with a thickness of 1.2 nm; the first doped polysilicon layer has a thickness of 30 nm and a phosphorus doping concentration of 3×10 17 cm -3 , the carbon doping concentration is 2×10 16 cm -3 ; The thickness of the silicon oxide layer is 1.1 nm; the thickness of the second doped polysilicon layer is 100 nm, and the phosphorus doping concentration is 4×10 21 cm -3 , the carbon doping concentration is 3×10 17 cm -3 , square resistance is 22Ω·sq -1 ;

[0074] The diffusion layer is located between the silicon substrate and the dielectric layer. The diffusion layer is a film layer doped with phosphorus in the N-type silicon substrate. The phosphorus doping concentration in the diffusion layer is 1×10 18 cm -3 ;

[0075] A first electrode, penetrating the first passivation layer and the first anti-reflection layer and making ohmic contact with the PN junction;

[0076] The second electrode penetrates the second passivation layer and is in ohmic contact with the doped layer.

[0077] Example 2

[0078] The difference between this embodiment and embodiment 1 is that:

[0079] In this embodiment, the second doped polysilicon layer includes a first doped sublayer and a second doped sublayer. The thickness of the first doped sublayer is 25 nm, and the concentration of the doped phosphorus element is 5*10 18 cm -3The thickness of the second doped sublayer is 75 nm, and the concentration of doped phosphorus is 3*10 21 cm -3 .

[0080] Example 3

[0081] The difference between this embodiment and embodiment 1 is that:

[0082] In this embodiment, the phosphorus doping concentration in the first doped polysilicon layer is 5×10 17 cm -3 The phosphorus doping concentration in the second doped polysilicon layer is 6×10 21 cm -3 .

[0083] Example 4

[0084] The difference between this embodiment and embodiment 1 is that:

[0085] In this embodiment, the first doped polysilicon layer and the second doped polysilicon layer are not doped with carbon elements.

[0086] Comparative Example 1

[0087] The difference between this embodiment and embodiment 1 is that:

[0088] In this embodiment, a silicon oxide layer is disposed between the dielectric layer and the first doped polysilicon layer, and the thickness is 1.1 nm.

[0089] Comparative Example 2

[0090] The difference between this comparative example and Example 1 is:

[0091] In this comparative example, no silicon oxide layer is disposed between the first doped polysilicon layer and the second doped polysilicon layer.

[0092] Comparative Example 3

[0093] The difference between this comparative example and Example 1 is:

[0094] In this comparative example, a silicon oxide layer is disposed between the first doped sublayer and the second doped sublayer in a direction away from the silicon substrate, and the thickness of the silicon oxide layer is 1.1 nm.

[0095] The solar cells of Example 1, Example 2, Comparative Examples 1 and Comparative Examples 2 were subjected to electrical performance tests, and performance tests in terms of open circuit voltage, short circuit current and fill factor were performed using a halm test sorting device. The halm machine is a device that simulates sunlight, and is equipped with an electronic load, data acquisition and computing equipment, etc., to test the electrical performance of solar cells. The results are shown in Table 1.

[0096] Table 1 Performance test results of solar cells

[0097]

[0098] It can be seen from the above table that the solar cell with the passivation contact structure in the present application has better performance. Comparing Example 1 with Examples 2 to 4, it can be seen that setting the second doped sublayer as the first doped sublayer and the second doped sublayer, setting the semiconductor conductive element doping concentration in the second doped polysilicon layer to be higher than that in the first doped polysilicon layer, and doping carbon in addition to the semiconductor conductive element in the first doped polysilicon layer and the second doped polysilicon layer are all beneficial to improving the performance of the solar cell.

[0099] Comparing Example 1 and Comparative Example 1, the dielectric layer and the first doped polysilicon layer are adjacently arranged, and the solar cell containing the passivation contact structure has a higher open circuit voltage, filling performance, short circuit current and photoelectric conversion efficiency than the cell in which a silicon oxide layer is arranged in the dielectric layer and the first doped polysilicon layer. This is because the dielectric layer and the first doped polysilicon layer are in direct contact, and the dielectric layer is relatively dense, so a small amount of semiconductor conductive elements but not a large amount can enter the dielectric layer, and then an appropriate amount of semiconductor conductive elements can enter the silicon substrate. The low concentration of doping can reduce the recombination of minority carriers at the interface, increase the passivation effect, and is beneficial to improving the performance of the passivation contact solar cell.

[0100] By comparing Example 1 and Comparative Example 2, it can be seen that the solar cell containing the passivation contact structure in which the silicon oxide layer is arranged in the first doped polysilicon layer and the second doped polysilicon layer has a higher open circuit voltage, filling performance, short circuit current and photoelectric conversion efficiency than the cell in which the silicon oxide layer is not arranged in the first doped polysilicon layer and the second doped polysilicon layer. This is because the silicon oxide layer can inhibit a large number of semiconductor conductive elements from penetrating into the dielectric layer and mainly blocks the semiconductor conductive elements on the surface, inhibits the mutual diffusion between the first doped polysilicon layer and the second doped polysilicon layer, increases the concentration of the surface semiconductor conductive elements, and thus improves the performance of the solar cell.

[0101] By comparing Example 1 and Comparative Example 3, it can be seen that providing a silicon oxide layer between the first doped sublayer and the second doped sublayer will lead to a decrease in the performance of the solar cell containing the passivation contact structure. This is because the silicon oxide layer blocks the diffusion of semiconductor conductive elements in the first doped sublayer and the second doped sublayer, which is not conducive to forming a uniform concentration gradient of semiconductor conductive element doping, thereby affecting the performance of the solar cell.

[0102] The above is a detailed introduction to a passivation contact structure, solar cell and photovoltaic module disclosed in the embodiments of the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the embodiments of the present application. The description of the above embodiments is only used to help understand the technical solutions and core ideas of the embodiments of the present application. At the same time, for general technicians in this field, according to the ideas of the embodiments 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 embodiments of the present application.

Claims

1. A passivation contact structure, characterized in that: The passivation contact structure comprises: A dielectric layer, wherein the thickness of the dielectric layer is 1.20 nm to 1.40 nm; A doped layer is provided on the dielectric layer, the doped layer comprising a first doped polysilicon layer, a silicon oxide layer and a second doped polysilicon layer arranged in sequence along a direction away from the dielectric layer; wherein the thickness of the first doped polysilicon layer is 20nm to 40nm, the thickness of the silicon oxide layer is 1.0nm to 2.0nm, and the thickness of the second doped polysilicon layer is 80nm to 100nm.

2. The passivation contact structure according to claim 1, characterized in that: The first doped polysilicon layer and the second doped polysilicon layer are both doped polysilicon layers doped with semiconductor conductive elements.

3. The passivation contact structure according to claim 1, characterized in that: The second doped polysilicon layer includes a first doped sublayer disposed close to the silicon oxide layer and a second doped sublayer disposed away from the silicon oxide layer.

4. The passivation contact structure according to claim 3, characterized in that: The thickness of the first doped sublayer is 25nm to 45nm; The thickness of the second doped sublayer is 35 nm to 55 nm.

5. A solar cell, characterized in that: The solar cell comprises a silicon substrate and a passivation contact structure as claimed in any one of claims 1 to 4, wherein the dielectric layer is arranged close to the silicon substrate, and the doping layer is arranged away from the silicon substrate.

6. The solar cell according to claim 5, characterized in that: A diffusion layer is provided between the silicon substrate and the dielectric layer. The diffusion layer, the first doped polysilicon layer, and the second doped polysilicon layer all have semiconductor conductive elements of the same conductive type.

7. The solar cell according to claim 6, characterized in that: The doping layer is a whole layer structure, and the position of the doping layer corresponds to both the metallized region of the solar cell and the non-metallized region of the solar cell.

8. A photovoltaic module, characterized in that: The photovoltaic component comprises the passivation contact structure according to any one of claims 1 to 4, and / or the photovoltaic component comprises the solar cell according to any one of claims 5 to 7.

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