Passivated contact cell, photovoltaic module and photovoltaic system

Abstract

The utility model discloses a passivation contact cell, a photovoltaic assembly and a photovoltaic system, the cell structure comprises a silicon wafer body, a front doping layer, a front passivation layer, a front metal electrode, a back doping layer, a back passivation layer and a back metal electrode, and a tunneling oxide layer is formed between the back doping layer and the back of the silicon wafer body. The back doping layer comprises doping structure layers in one-to-one correspondence with the back metal electrodes, and the back passivation layer comprises a TCO film layer and a cap layer. On one hand, the cap layer is used for blocking hydrogen atoms escaping from the outer surface of the TCO to the outside, the proportion of the hydrogen atoms in the TCO is effectively improved, attenuation of the migration rate of the double-layer film is reduced, and therefore short-circuit current is optimized, filling factors are improved, and the battery performance is improved; and on the other hand, through the arrangement of the local doping layer and the TCO film layer, the thickness of the doping structure layer is reduced, the cost is reduced, the current loss of parasitic absorption is reduced, and the photoelectric conversion efficiency is improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of solar cells, and in particular relates to a passivation contact cell, and also relates to a photovoltaic component and a photovoltaic system. Background Art

[0002] At present, high-efficiency, low-cost solar cells are key components for photovoltaic power generation. This field has become the focus of academic and industrial attention. On the market, N-type is replacing P-type, and there are many solutions to replace PERC cells. TOPCon, HJT, and BC cell structures are unanimously recognized by the industry, with little differentiation, and are approaching the efficiency bottleneck. However, flexible solar cells such as perovskite are still in the development stage, and stability is difficult to control. There is still a lot of room for efficiency improvement, and there is still a long way to go before marketization, so it is urgent to develop a new structure.

[0003] However, conventional TOPCon cells on the market generally include metal electrodes, passivation layers, doping layers, and silicon wafers, wherein the doping layer covers the front and back sides of the silicon wafer, and the passivation layer constitutes an anti-reflection layer. Therefore, it has the following technical defects:

[0004] 1. The anti-reflection layer is composed of a passivation layer, which only plays an anti-reflection role without considering its compatibility and current loss. In short, it is impossible to optimize the short-circuit current and fill factor, that is, it is impossible to improve the compatibility of TOPCon cells;

[0005] 2. The thickness of the doped layer is generally around 120-130 nm, and the area that affects product performance only corresponds to the part where the metal electrode is located. Therefore, it not only increases the thickness of the battery cell, but also causes waste of resources of the excess doped layer, thereby increasing the production cost of the battery cell. Utility Model Content

[0006] The technical problem to be solved by the utility model is to overcome the deficiencies of the prior art and provide an improved passivation contact battery.

[0007] At the same time, the utility model also relates to a photovoltaic component and a photovoltaic system.

[0008] In order to solve the above technical problems, the technical solutions adopted by the utility model are as follows:

[0009] A passivation contact cell comprises a silicon wafer body; a front doping layer, a front passivation layer and a front metal electrode formed on the front side of the silicon wafer body; a back doping layer, a back passivation layer and a back metal electrode formed on the back side of the silicon wafer body, in particular, a tunneling oxide layer is formed between the back doping layer and the back side of the silicon wafer body, the back doping layer comprises a doping structure layer corresponding to the back metal electrode one by one, the back passivation layer comprises a TCO film layer formed on the back side of the tunneling oxide layer and the doping structure layer; a cap layer is formed on the back side of the TCO film layer, and the back metal electrode is correspondingly formed on the back side of the cap layer.

[0010] Preferably, the width of the doped structural layer is greater than or equal to the width of the back metal electrode. From a cost perspective, it is best if the width of the doped structural layer strip is equal to the width of the back metal electrode.

[0011] According to a specific implementation and preferred aspect of the utility model, the thickness of the doped structural layer is 15 to 30 nm. At the same time, multiple doped structural layers constitute a poly-Si layer. Here, the TCO film layer and the cap layer are applied to the TOPCon battery structure. The TCO film layer ensures sufficient lateral conductivity, so that the local poly-Si layer thickness does not exceed 30 nm, which is beneficial to reduce the contact resistance between the TCO film layer and the substrate. At the same time, the hydrogen atoms on the outer surface of the TCO will escape to the outside world. The cap layer can block this escape, effectively increasing the proportion of hydrogen atoms in the TCO, reducing the attenuation of the double-layer film mobility, and improving stability; therefore, applying the TCO film layer and the cap layer to the TOPCon battery structure can increase the carrier concentration, optimize the short-circuit current and fill factor. At the same time, it makes the TOPCon battery more compatible with the perovskite battery, taking the first step for the next step of stacked solar cells.

[0012] Preferably, the thickness of the TCO film layer is 65-85 nm; and / or the thickness of the cap layer is 70-90 nm.

[0013] In some specific embodiments, the silicon wafer body is an N-type silicon substrate, the front doped layer is a front P-type emitter. The front passivation layer is an anti-reflection layer and includes an AlO3 passivation layer and a SiN X Passivation layer or SiO2 layer.

[0014] According to a specific implementation and preferred aspect of the utility model, the tunneling oxide layer is a SiO2 layer; and / or the cap layer is a silicon oxide layer, a silicon nitride layer, a silicon oxynitride layer, a silicon carbide layer, an aluminum oxide layer, a gallium oxide layer, a zinc oxide layer, a titanium oxide layer or a TCO film layer; and / or the TCO film layer is a fluorine-doped tin oxide layer, an aluminum-doped tin oxide layer or an antimony-doped tin oxide layer; and / or the TCO film layer and the cap layer constitute an anti-reflection layer.

[0015] In addition, the TCO film layer, namely transparent conductive oxide (Transparent conductive Oxides), is a transparent conductive oxide film plated on the substrate material. It has good carrier mobility and transmittance, and at the same time, it regulates the work function to achieve good interface contact. Its function is to collect photogenerated carriers, and at the same time, it acts as an anti-reflection layer to reduce the reflection loss of light, and as a barrier layer to prevent metals such as silver from diffusing into the silicon layer. Therefore, the TCO film layer has excellent anti-reflection performance. At the same time, its lateral conductivity can reduce the thickness of the poly-Si layer of TOPCON to a certain extent. A layer of 15 to 30nm poly-Si is deposited on the front side using LPCVD, and then a quartz mask is used to shield the main gate area. After removing the poly-Si, the quartz mask is removed to obtain a structure in which there is a poly-Si layer in the main gate area, but no poly-Si layer in other areas. This reduces costs while reducing current losses due to parasitic absorption and improves photoelectric conversion efficiency.

[0016] Another technical solution of the utility model is: a photovoltaic module, which includes a front packaging layer, a photovoltaic cell, and a back packaging layer, wherein the photovoltaic cell is the above-mentioned passivated contact cell.

[0017] Another technical solution of the utility model is: a photovoltaic system, which includes the above-mentioned photovoltaic module, wherein there are one or more photovoltaic modules, and when there are multiple photovoltaic modules, the multiple photovoltaic modules are connected. In short, the multiple photovoltaic modules are connected (connected in series).

[0018] Due to the implementation of the above technical solution, the utility model has the following advantages compared with the prior art:

[0019] The existing passivated contact battery, which consists of a passivation layer forming an anti-reflection layer, only plays an anti-reflection role, without considering its compatibility and the current loss that will be caused. In short, it is impossible to optimize the short-circuit current and the fill factor, that is, it is impossible to improve the compatibility of the TOPCon battery; at the same time, the thickness formed by the doping layer is generally about 120 to 130 nm, and the area that affects the product performance only corresponds to the part where the metal electrode is located. Therefore, not only the thickness of the battery structure is increased, but also the resources of the redundant doping layer are wasted, thereby increasing the production cost of the battery structure and other deficiencies. The overall design of the passivated contact battery of the utility model cleverly solves the various deficiencies of the existing structure. The passivated contact cell is adopted, and a cap layer is added after TCO is deposited on the back side by reactive plasma, which is beneficial to reducing the contact resistance between TCO and the substrate. At the same time, the gate area formed by the metal electrode on the back side has a doping layer, while other areas have no doping layer structure, and an anti-reflection layer is formed in the passivation layer to form the cell structure. Therefore, on the one hand, the utility model uses the cap layer to block hydrogen atoms escaping from the outer surface of the TCO to the outside, effectively increasing the proportion of hydrogen atoms in the TCO, reducing the attenuation of the double-layer film mobility, thereby optimizing the short-circuit current, increasing the fill factor, and improving the cell performance; on the other hand, through the arrangement of the local doping layer and the TCO film layer, not only the thickness of the doping structure layer is thinned, but also the current loss of parasitic absorption is reduced while reducing the cost, thereby improving the photoelectric conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of Example 1;

[0021] Figure 2 for Figure 1 Schematic diagram of structural decomposition;

[0022] Wherein: 1. silicon wafer body; 2. front doping layer; 3. front passivation layer; 30. AlO3 passivation layer; 31. SiN X Passivation layer or SiO2 layer; 4. Front metal electrode; 5. Back doping layer; 50. Doping structure layer; 6. Back passivation layer; 60. TCO film layer; 61. Cap layer; 7. Back metal electrode; 8. Tunneling oxide layer. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned purposes, features and advantages of the utility model more obvious and easy to understand, the utility model is described in detail below in conjunction with the accompanying drawings and specific embodiments. In the following description, many specific details are set forth to facilitate a full understanding of the utility model. However, the utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the utility model, so the utility model is not limited by the specific embodiments disclosed below.

[0024] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0025] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present utility model, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0026] In the present invention, unless otherwise clearly defined and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0027] In the utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0028] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0029] Example 1

[0030] like Figure 1 and Figure 2 As shown, the passivation contact cell provided in this embodiment includes a silicon wafer body 1; a front doping layer 2, a front passivation layer 3 and a front metal electrode 4 formed on the front side of the silicon wafer body 1; and a back doping layer 5, a back passivation layer 6 and a back metal electrode 7 formed on the back side of the silicon wafer body 1.

[0031] In some specific embodiments, the silicon wafer body 1 is an N-type silicon substrate, and the front doping layer 2 in the front structure of the battery is a front P-type emitter. The front passivation layer 3 is an anti-reflection layer and includes an AlO3 passivation layer 30 and a SiN X Passivation layer or SiO2 layer 31 .

[0032] In the back structure of the passivated contact cell, a tunneling oxide layer 8 is formed between the back doping layer 5 and the back of the silicon wafer body 1, wherein the tunneling oxide layer 8 is a SiO2 layer. The back doping layer 5 includes a doping structure layer 50 corresponding to the back metal electrode 7, and the back passivation layer 6 includes a TCO film layer 60 formed on the back of the tunneling oxide layer 8 and the doping structure layer 50; a cap layer 61 formed on the back of the TCO film layer 60, and the back metal electrode 7 is correspondingly formed on the back of the cap layer 61, and the TCO film layer 60 and the cap layer 61 constitute an anti-reflection layer.

[0033] In some specific embodiments, the width of the doped structural layer 50 is equal to the width of the back metal electrode 7; the thickness of the doped structural layer 50 is 15 to 30 nm, and at the same time, multiple doped structural layers constitute a poly-si layer. Here, TCO and the cap layer are applied to the TOPCon battery structure so that the local poly-si layer thickness does not exceed 30 nm, which is beneficial to reduce the contact resistance between TCO and the substrate. At the same time, the hydrogen atoms on the outer surface of the TCO will escape to the outside world. The cap layer can block this escape, effectively increasing the proportion of hydrogen atoms in the TCO, reducing the attenuation of the double-layer film mobility, improving stability, increasing carrier concentration, and optimizing short-circuit current and fill factor. At the same time, it makes the TOPCon battery more compatible with the perovskite battery, taking the first step for the next step of stacked solar cells; the thickness of the TCO film layer is 65 to 85 nm; the thickness of the cap layer is 70 to 90 nm.

[0034] In some specific embodiments, TCO can be any one including but not limited to ITO, FTO, AZO. Specifically, ITO is indium tin oxide, FTO is fluorine-doped tin oxide, AZO is aluminum-doped tin oxide, and ATO is antimony-doped tin oxide. The cap layer 61 is a silicon oxide layer, a silicon nitride layer, a silicon oxynitride layer, a silicon carbide layer, an aluminum oxide layer, a gallium oxide layer, a zinc oxide layer, a titanium oxide layer or a TCO film layer. Optimally, the cap layer 61 can be a SiO2 layer, a SiN X layer or TCO film layer.

[0035] In addition, the above-mentioned battery cells were used to make samples and their performance was tested. The results are shown in Table 1.

[0036] Table 1

[0037] sample Eta Uoc Isc FF R RshuntDfDr Sample 1 25.3036 0.7252 13.797 84.3114 0.00091 3951.416104 Sample 2 25.2588 0.7344 13.8212 82.9567 0.0012 4543.485079 Sample 3 25.2547 0.7354 13.7597 83.2008 0.0011 4291.604304

[0038] Example 2

[0039] The photovoltaic module involved in this embodiment includes a front encapsulation layer, a photovoltaic cell, and a back encapsulation layer, wherein the photovoltaic cell is the passivated contact cell in the above-mentioned embodiment 1.

[0040] Example 3

[0041] The photovoltaic system involved in this embodiment includes the photovoltaic components involved in Embodiment 2, wherein there are two or three or more photovoltaic components, and the multiple photovoltaic components are interconnected (generally connected in series).

[0042] Meanwhile, there may be only one photovoltaic module, that is, a photovoltaic system consisting of a single photovoltaic module; or there may be two or three or more photovoltaic modules, and the multiple photovoltaic modules may be relatively connected in series and / or in parallel.

[0043] In summary, the passivated contact cell is adopted, and the TCO is deposited on the back by reactive plasma and then the cap layer is added, which is beneficial to reduce the contact resistance between TCO and the substrate. At the same time, the gate area formed by the metal electrode on the back has a doping layer, while other areas have no doping layer structure, and an anti-reflection layer is formed in the passivation layer to form the cell structure. Therefore, on the one hand, the hydrogen atoms on the outer surface of the TCO will escape to the outside, and the cap layer blocks this escape, which effectively increases the proportion of hydrogen atoms in the TCO and reduces the attenuation of the mobility of the double-layer film, thereby optimizing the short-circuit current, improving the fill factor, and improving the battery performance; on the other hand, through the setting of the local doping layer and the TCO film layer, not only the thickness of the poly-si layer is thinned, but also the cost is reduced while reducing the current loss of parasitic absorption, thereby improving the photoelectric conversion efficiency; the third aspect of the TCO film layer, that is, the transparent conductive oxide (Transparent conductive Oxides) is a transparent conductive oxide film coated on the substrate material, which has good carrier mobility and transmittance, and at the same time adjusts the work function to achieve good interface contact. Its role is to collect photogenerated carriers, and at the same time, it acts as an anti-reflection layer to reduce the reflection loss of light, and as a barrier layer to prevent silver and other metals from diffusing into the silicon layer. Therefore, the TCO film layer has excellent anti-reflection performance. At the same time, its lateral conductive performance can reduce the thickness of the poly-Si layer of TOPCON to a certain extent. A 15-30nm poly-Si layer is deposited on the front side using LPCVD, and then a stone is used. The quartz mask is used to shield the main grid area, and the poly-Si is removed before the quartz mask is removed to obtain a structure in which the main grid area has a poly-Si layer, while other areas do not have poly-Si, which reduces costs while reducing current losses caused by parasitic absorption and improves photoelectric conversion efficiency; fourthly, according to the Fresnel principle, a transparent film layer with a certain thickness and a certain refractive index covering the surface can promote destructive interference of reflected light, thereby reducing reflection; fifthly, the front encapsulation layer, the passivated contact crystalline silicon cell, and the back encapsulation layer constitute a photovoltaic module, and then multiple photovoltaic modules are connected to form a photovoltaic system with the best efficiency and effect.

[0044] The above detailed description of the utility model is intended to enable people familiar with the technology in this field to understand the content of the utility model and implement it. It is not intended to limit the protection scope of the utility model. All equivalent changes or modifications made according to the spirit of the utility model should be included in the protection scope of the utility model.

Claims

1. A passivation contact cell, comprising a silicon wafer body (1); a front doping layer (2), a front passivation layer (3) and a front metal electrode (4) formed on the front side of the silicon wafer body (1); and a back doping layer (5), a back passivation layer (6) and a back metal electrode (7) formed on the back side of the silicon wafer body (1), characterized in that: A tunneling oxide layer (8) is formed between the back doping layer (5) and the back side of the silicon wafer body (1); the back doping layer (5) comprises a doping structure layer (50) corresponding to the back metal electrode (7); the back passivation layer (6) comprises a TCO film layer (60) formed on the back side of the tunneling oxide layer (8) and the doping structure layer (50); and a cap layer (61) formed on the back side of the TCO film layer (60); and the back metal electrode (7) is formed on the back side of the cap layer (61).

2. The passivated contact cell according to claim 1, characterized in that: The width of the doped structure layer (50) is greater than or equal to the width of the back metal electrode (7).

3. The passivated contact cell according to claim 1, characterized in that: The thickness of the doped structure layer (50) is 15-30 nm.

4. The passivated contact cell according to claim 1, 2 or 3, characterized in that: The plurality of doped structure layers (50) constitute a poly-si layer.

5. The passivated contact cell according to claim 1, characterized in that: The thickness of the TCO film layer (60) is 65-85 nm; and / or the thickness of the cap layer (61) is 70-90 nm.

6. The passivated contact cell according to claim 1, characterized in that: The silicon wafer body (1) is an N-type silicon substrate, and the front doped layer (2) is a front P-type emitter.

7. The passivated contact cell according to claim 1, characterized in that: The front passivation layer (3) is an anti-reflection layer and includes an AlO3 passivation layer and a SiN X Passivation layer or SiO2 layer.

8. The passivated contact cell according to claim 1, characterized in that: The tunneling oxide layer (8) is a SiO2 layer; and / or the cap layer (61) is a silicon oxide layer, a silicon nitride layer, a silicon oxynitride layer, a silicon carbide layer, an aluminum oxide layer, a gallium oxide layer, a zinc oxide layer, a titanium oxide layer or a TCO film layer (60); and / or the TCO film layer (60) is a fluorine-doped tin oxide layer, an aluminum-doped tin oxide layer or an antimony-doped tin oxide layer; and / or the TCO film layer (60) and the cap layer (61) constitute an anti-reflection layer.

9. A photovoltaic module, comprising a front encapsulation layer, a photovoltaic cell, and a back encapsulation layer, characterized in that: The photovoltaic cell is a passivated contact cell according to any one of claims 1 to 8.

10. A photovoltaic system, characterized in that: The photovoltaic system comprises the photovoltaic assembly as claimed in claim 9, wherein there are one or more photovoltaic assemblies, and when there are multiple photovoltaic assemblies, the multiple photovoltaic assemblies are interconnected.

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