Back contact photovoltaic cell with high-concentration co-doped region as well as preparation method and application of back contact photovoltaic cell

Abstract

The invention belongs to the technical field of back contact photovoltaic cells, and particularly relates to a back contact photovoltaic cell with high-concentration co-doped regions and a manufacturing method and application thereof.The back contact photovoltaic cell with the high-concentration co-doped regions is characterized in that N-type doped regions and P-type doped regions which are alternately distributed are arranged on the backlight face of an intrinsic amorphous silicon layer, and the high-concentration co-doped regions are arranged between the N-type doped regions and the P-type doped regions; a doping source of the co-doped region comprises doping source phosphorus of the N-type doped region and doping source boron of the P-type doped region, the co-doped region, the doping source of the N-type doped region and the doping source of the P-type doped region form a specific concentration gradient structure, and the specific concentration gradient structure meets the condition that the doping concentration of phosphorus contained in the co-doped region is greater than that of phosphorus contained in the N-type doped region; the doping concentration of boron contained in the co-doped region is greater than the doping concentration of boron in the P-type doped region. The carrier transport and collection efficiency is optimized, the fill factor and open-circuit voltage are improved, the cell conversion efficiency and stability are improved, the preparation process is simple, and multiple times of opening etching are not needed.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of back contact photovoltaic cells, and particularly relates to a back contact photovoltaic cell with a high-concentration co-doped region, a manufacturing method thereof, and an application. BACKGROUND

[0002] In a conventional photovoltaic cell structure, carrier recombination within the cell is an unavoidable phenomenon, which seriously affects the conversion efficiency of the cell. In order to reduce carrier recombination, researchers have tried various methods, including optimizing the cell structure, improving material properties, and adopting new cell technologies. For example, by introducing a passivation layer to reduce surface recombination, or adopting a heterojunction structure to improve the separation efficiency of carriers. However, these methods have certain limitations in practical application, such as high cost, complex process, limited effect, etc.

[0003] Although existing technologies have made some progress in reducing carrier recombination, there are still some problems and deficiencies: first, the traditional passivation layer material and structure design are difficult to achieve efficient inhibition of carrier recombination, resulting in limited improvement of open-circuit voltage and fill factor of the cell. Second, although the heterojunction structure can improve the separation efficiency of carriers, its preparation process is complex (such as generally requiring multiple etching openings), high cost, and difficult to be applied on a large scale. In addition, existing technical solutions often accompany unstable cell performance and shortened service life while improving the conversion efficiency of the cell.

[0004] It should be noted that this part of the present application only provides background technology related to the present application, and does not necessarily constitute prior art or known technology. SUMMARY

[0005] The purpose of the present application is to overcome the defects of the prior art, such as limited improvement of open-circuit voltage and fill factor of the cell in the existing back contact photovoltaic cell, limited improvement of cell conversion efficiency, and complex preparation process. The present application provides a back contact photovoltaic cell with a high-concentration co-doped region, a manufacturing method thereof, and an application. The present application optimizes the carrier transport and collection efficiency, improves the fill factor and open-circuit voltage, improves the cell conversion efficiency and stability, and the preparation process is simple without multiple etching openings.

[0006] To achieve the above object, in a first aspect, the present application provides a back contact photovoltaic cell with high concentration co-doped region, which comprises a silicon substrate, an intrinsic amorphous silicon layer arranged on the back surface of the silicon substrate, and N-type doped regions and P-type doped regions arranged alternately on the back surface of the intrinsic amorphous silicon layer, and a high concentration co-doped region arranged between the N-type doped regions and the P-type doped regions, wherein the doping source of the co-doped region comprises phosphorus of the N-type doped regions and boron of the P-type doped regions, the co-doped region and the N-type doped regions and the P-type doped regions form a specific concentration gradient structure, and the specific concentration gradient structure satisfies: the doping concentration of phosphorus contained in the co-doped region is greater than the doping concentration of phosphorus in the N-type doped regions, and the doping concentration of boron contained in the co-doped region is greater than the doping concentration of boron in the P-type doped regions.

[0007] In some preferred embodiments of the present application, the ratio of the highest doping concentration of phosphorus contained in the co-doped region to the highest doping concentration of phosphorus in the N-type doped regions is (1.1-10):1, and / or the ratio of the highest doping concentration of boron contained in the co-doped region to the highest doping concentration of boron in the P-type doped regions is (1.05-8):1.

[0008] In some preferred embodiments of the present application, the ratio of the highest doping concentration of phosphorus contained in the co-doped region to the highest doping concentration of phosphorus in the N-type doped regions is (1.3-5):1, and / or the ratio of the highest doping concentration of boron contained in the co-doped region to the highest doping concentration of boron in the P-type doped regions is (1.2-3.5):1.

[0009] In some preferred embodiments of the present application, the doping concentration of phosphorus and the doping concentration of boron contained in the co-doped region are each independently 2e19cm-5e23cm. -3 -5e23cm -3 ; and / or,

[0010] The doping concentration of phosphorus in the N-type doped regions is 2e18cm -3 -8e22cm -3 , and the doping concentration of boron in the P-type doped regions is 2e18cm -3 -8e22cm -3 .

[0011] In some preferred embodiments of the present application, the co-doped region has hydrogen doping, and the hydrogen doping concentration in the co-doped region is higher than the hydrogen doping concentration in the N-type doped regions and / or the P-type doped regions.

[0012] In some preferred embodiments of the present application, the ratio of the hydrogen doping concentration in the co-doped region to the hydrogen doping concentration in the N-type doped regions or the P-type doped regions is (0.5-3):1, and / or the hydrogen doping concentration of the co-doped region is 1e19cm -3 -5e22cm -3 .

[0013] In some preferred embodiments of the present application, the back contact photovoltaic cell further has at least one of the following structures:

[0014] Structure one, the ratio of the width of the co-doped region to the width of the N-type doped region or the P-type doped region is (0.01-0.4):1, and / or, the ratio of the thickness of the co-doped region to the thickness of the N-type doped region or the P-type doped region is (0.5-1.4):1;

[0015] Structure two, the width of the co-doped region is 5-130 μm, and / or, the thickness of the co-doped region is 5-30 nm;

[0016] Structure three, the width of the N-type doped region and the P-type doped region is independently 200-1000 μm, and / or, the thickness of the N-type doped region and the P-type doped region is independently 5-20 nm;

[0017] Structure four, the thickness of the intrinsic amorphous silicon layer is 5-15 nm, and / or, the ratio of the thickness of the intrinsic amorphous silicon layer to the thickness of the N-type doped region or the P-type doped region is (0.3-2):1;

[0018] Structure five, in the width direction, the N-type doped region and the co-doped region, and the co-doped region and the P-type doped region are in contact with each other and are continuously distributed as a whole;

[0019] Structure six, the N-type doped region and the P-type doped region are respectively a doped region formed by doping part of the intrinsic amorphous silicon layer, or are respectively a doped film layer deposited on the back surface of the intrinsic amorphous silicon layer;

[0020] Structure seven, the back contact photovoltaic cell further comprises a light-receiving surface passivation anti-reflection layer arranged on the light-receiving surface of the silicon substrate;

[0021] Structure eight, the back contact photovoltaic cell further comprises: a conductive film layer arranged on the outer surface of the N-type doped region and the P-type doped region, and a metal electrode arranged outside the conductive film layer, wherein an isolation groove is arranged between the conductive film layer arranged on the outer surface of the N-type doped region and the conductive film layer arranged on the outer surface of the P-type doped region, and at least part of the isolation groove is located on the outer surface of the co-doped region;

[0022] Structure nine, the light-receiving surface of the silicon substrate is a textured surface, and the back surface is a polished surface.

[0023] In a second aspect, the present application provides a preparation method of a back contact photovoltaic cell, which is used to prepare the back contact photovoltaic cell with a high-concentration co-doped region in the first aspect, and the preparation method comprises the following steps:

[0024] S1, providing a silicon substrate;

[0025] S2, depositing an intrinsic amorphous silicon layer on the back surface of the silicon substrate;

[0026] S3, presetting N-type doped regions, P-type doped regions and co-doped regions between the N-type doped regions and the P-type doped regions in an outer surface of the intrinsic amorphous silicon layer in an alternating distribution;

[0027] The N-type doped regions, the P-type doped regions and the co-doped regions are formed in the respective preset regions by using a template method; wherein the co-doped regions contain phosphorus at a doping concentration greater than the phosphorus doping concentration in the N-type doped regions, and contain boron at a doping concentration greater than the boron doping concentration in the P-type doped regions, thereby forming a specific concentration gradient structure.

[0028] In some preferred embodiments of the present application, the preparation method further comprises at least one of the following processes:

[0029] Process one, the N-type doped regions, the P-type doped regions and the co-doped regions are formed in the respective preset regions by using a template method; wherein the co-doped regions contain phosphorus at a doping concentration greater than the phosphorus doping concentration in the N-type doped regions, and contain boron at a doping concentration greater than the boron doping concentration in the P-type doped regions, thereby forming a specific concentration gradient structure.

[0030] Process two, the preparation method further comprises:

[0031] S4, depositing a conductive film layer on the outer surface of the intrinsic amorphous layer after the doping of S3, and opening and forming an isolation groove on at least part of the conductive film layer located on the outer surface of the co-doped region;

[0032] S5, forming metal electrodes on the outer surfaces of the conductive film layers corresponding to the N-type doped regions and the P-type doped regions, respectively.

[0033] In a third aspect, the present application provides a photovoltaic module comprising the back contact photovoltaic cell with the high-concentration co-doped region according to the first aspect, or the back contact photovoltaic cell prepared by the preparation method of the back contact photovoltaic cell according to the second aspect.

[0034] Advantages:

[0035] The present application optimizes the carrier transport and collection efficiency, effectively reduces carrier recombination, improves the fill factor and open circuit voltage, and improves the battery conversion efficiency and stability.

[0036] The preparation method of the present application simplifies the preparation process compared with the complex preparation process of the existing heterojunction structure, reduces the production cost, is conducive to large-scale application, and simultaneously improves the battery conversion efficiency.

[0037] In the preferred scheme of the present application, the co-doped region adopts a moderately high H doping concentration relative to the N-type doped region and the P-type doped region, which can further reduce recombination and optimize transport, and avoid causing battery performance degradation. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced below, and it should be understood that the following drawings only show some embodiments of the present application, and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0039] Figure 1 A structural schematic diagram of one specific embodiment of the back contact photovoltaic cell of the present application.

[0040] MARKED FOR THE DRAWINGS

[0041] Silicon substrate 1, intrinsic amorphous silicon layer 2, N-type doped region 3, P-type doped region 4, co-doped region 5, conductive film layer 6, isolation groove 7, metal electrode 8. DETAILED DESCRIPTION

[0042] In the present application, the terms "first", "second" are used only for descriptive purpose, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise explicitly specified and limited.

[0043] In the present application, unless otherwise explicitly specified and limited, the "on" or "under" of the first feature to the second feature can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the "over", "above" and "on" of the first feature to the second feature can be that the first feature is directly above or obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The "under", "below" and "under" of the first feature to the second feature can be that the first feature is directly below or obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0044] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as implicitly split into this precise range unless otherwise indicated. For values that are ostensibly continuous within a range, endpoints between any stated value and any other stated value, between an endpoint and a stated value, and between stated value and a stated value make no representation, either express or implied, that the values broadly intermediate to those values are actually available. The present application is also drawn to new ranges including the value "from any one of X to Y" in place of "from X or more to Y or less"; that is any range of values beginning with a minimum value of X or more and ending with a maximum value of Y or less. Moreover, the terms "optional", "optionally" are intended to mean that the subsequently described feature can or can not be present or can or can not be utilized.

[0045] In the present application, the term "near" refers to the inside of the silicon substrate, and the term "far" refers to the outside of the silicon substrate.

[0046] In the first aspect, the present application provides a back contact photovoltaic cell with a high concentration co-doped region, the back contact photovoltaic cell comprising a silicon substrate, an intrinsic amorphous silicon layer disposed on the back surface of the silicon substrate, and N-type doped regions and P-type doped regions alternately disposed on the back surface of the intrinsic amorphous silicon layer, and a high concentration co-doped region disposed between the N-type doped regions and the P-type doped regions, wherein the doping source of the co-doped region comprises phosphorus, which is the doping source of the N-type doped regions, and boron, which is the doping source of the P-type doped regions, the co-doped region and the N-type doped regions and the P-type doped regions form a specific concentration gradient structure, and the specific concentration gradient structure satisfies that the doping concentration of phosphorus contained in the co-doped region is greater than the doping concentration of phosphorus in the N-type doped regions, and the doping concentration of boron contained in the co-doped region is greater than the doping concentration of boron in the P-type doped regions. The back contact photovoltaic cell of the present application has a specific concentration gradient structure comprising a high concentration co-doped region, optimizes the carrier transport and collection efficiency, effectively reduces the carrier recombination, improves the fill factor and open circuit voltage, and improves the cell conversion efficiency and stability.

[0047] In some preferred embodiments of the present application, the ratio of the highest doping concentration of phosphorus contained in the co-doped region to the highest doping concentration of phosphorus in the N-type doped region is (1.1-10):1, which can be specifically 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, 2.2:1, 2.5:1, 2.8:1, 2.9:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, 7.5:1, 8:1, 8.5:1, 9:1, 9.5:1, or 10:1, and ranges between any two point values.

[0048] In some more preferred embodiments of the present application, the ratio of the highest doping concentration of phosphorus contained in the co-doped region to the highest doping concentration of phosphorus in the N-type doped region is (1.3-5):1. With this preferred scheme, the collection efficiency of electrons is more improved.

[0049] In some preferred embodiments of the present application, the ratio of the highest doping concentration of boron contained in the co-doped region to the highest doping concentration of boron in the P-type doped region is (1.05-8):1, which can be specifically 1.05:1, 1.08:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.75:1, 1.8:1, 1.83:1, 1.84:1, 1.85:1, 1.87:1, 1.9:1, 2:1, 2.2:1, 2.5:1, 2.8:1, 2.9:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, 7.5:1, or 8:1, and ranges between any two point values.

[0050] In some more preferred embodiments of the present application, the ratio of the highest doping concentration of boron contained in the co-doped region to the highest doping concentration of boron in the P-type doped region is (1.2-3.5):1, which is more conducive to improving the collection efficiency of holes.

[0051] In some preferred embodiments of the present application, the phosphorus doping concentration and the boron doping concentration contained in the co-doped region are each independently in the range of 2e19cm-5e23cm-3. -3 -5e23cm-3. -3 The phosphorus doping and the boron doping contained in the co-doped region of the present application can each be uniform doping or non-uniform doping, such as gradient doping, as long as the specific concentration gradient structure with a high-concentration co-doped region of the present application is met.

[0052] In some preferred embodiments of the present application, the phosphorus doping concentration in the N-type doped region is in the range of 2e18cm-3. -3 -8e22cm-3.-3 boron doping concentration in the P-type doped region is 2e18cm -3 -8e22cm -3 .

[0053] In some preferred embodiments of the present application, the co-doped region has hydrogen doping.

[0054] Preferably, the hydrogen doping concentration in the co-doped region is higher than the hydrogen doping concentration in the N-type doped region and / or the P-type doped region. The co-doped region of the present application adopts a moderately high H doping concentration relative to the N-type doped region and the P-type doped region, which can further reduce recombination, optimize transport, while avoiding causing battery performance degradation.

[0055] In some preferred embodiments of the present application, the ratio of the hydrogen doping concentration in the co-doped region to the hydrogen doping concentration in the N-type doped region or the P-type doped region is (0.5-3):1, which can be specifically 0.5:1, 0.6:1, 0.7:1, 0.8:1, 1:1, 1.1:1, 1.15:1, 1.2:1, 1.25:1, 1.3:1, 1.4:1, 1.45:1, 1.5:1, 1.55:1, 1.6:1, 1.7:1, 1.75:1, 1.8:1, 1.83:1, 1.84:1, 1.85:1, 1.87:1, 1.9:1, 2:1, 2.2:1, 2.5:1, 2.8:1, 2.9:1, or 3:1, and ranges between any two point values. With this preferred scheme, it is more conducive to reducing the bulk and interface defects in the co-doped region, thereby further effectively reducing carrier recombination, improving the fill factor and open circuit voltage, and improving the battery conversion efficiency and stability.

[0056] In some preferred embodiments of the present application, the hydrogen doping concentration of the co-doped region is 1e19cm -3 -5e22cm -3 .

[0057] In some preferred embodiments of the present application, the ratio of the width of the co-doped region to the N-type doped region or the P-type doped region is (0.01-0.4):1, which can be specifically 0.01:1, 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.06:1, 0.07:1, 0.1:1, 0.12:1, 0.15:1, 0.17:1, 0.2:1, 0.22:1, 0.25:1, 0.27:1, 0.3:1, 0.32:1, 0.35:1, 0.37:1, 0.39:1, or 0.4:1, and ranges between any two point values. With the co-doped region of the present application having a suitable width ratio to the N-type doped region and the P-type doped region, it is more conducive to suppressing interface recombination and reducing the risk of short circuit.

[0058] In some preferred embodiments of the present application, the ratio of the thickness of the co-doped region to the thickness of the N-type doped region or the P-type doped region is (0.5-1.4):1, for example specifically 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.2:1, 1.3:1, 1.35:1, or 1.4:1, and ranges between any two point values. The present application employs a co-doped region with a suitable thickness ratio to the N-type doped region and the P-type doped region, which is more conducive to forming effective field passivation and preventing leakage.

[0059] In some preferred embodiments of the present application, the width of the co-doped region is 5-130 μm.

[0060] In some preferred embodiments of the present application, the thickness of the co-doped region is 5-30 nm.

[0061] In some preferred embodiments of the present application, the width of the N-type doped region and the P-type doped region is independently 200-1000 μm. The width of the N-type doped region and the P-type doped region can be the same or different.

[0062] In some preferred embodiments of the present application, the thickness of the N-type doped region and the P-type doped region is independently 5-20 nm. The thickness of the N-type doped region and the P-type doped region can be the same or different.

[0063] In some preferred embodiments of the present application, the thickness of the intrinsic amorphous silicon layer is 5-15 nm.

[0064] In some preferred embodiments of the present application, the ratio of the thickness of the intrinsic amorphous silicon layer to the thickness of the N-type doped region or the P-type doped region is (0.3-2):1, for example specifically 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.2:1, 1.3:1, 1.35:1, 1.4:1, 1.5:1, 1.7:1, 1.8:1, 1.9:1, or 2:1, and ranges between any two point values. The present application employs an intrinsic amorphous silicon layer with a suitable thickness ratio to the N-type doped region and the P-type doped region, which is more conducive to achieving good passivation and selective contact of carriers, and improving the conversion efficiency of the cell.

[0065] In some preferred embodiments of the present application, in the width direction, the N-type doped region and the co-doped region, and the co-doped region and the P-type doped region are in contact with each other and are continuously distributed as a whole.

[0066] In some preferred embodiments of the present application, the N-type doped region and the P-type doped region are respectively a doped region formed by doping part of the intrinsic amorphous silicon layer, or are respectively a doped film layer deposited additionally on the back surface of the intrinsic amorphous silicon layer.

[0067] In some preferred embodiments of the present application, the back contact photovoltaic cell further comprises a light-receiving surface passivation and anti-reflection layer disposed on the light-receiving surface of the silicon substrate. The light-receiving surface passivation and anti-reflection layer comprises a passivation layer and / or an anti-reflection layer, which can be used in the present application, and specific reference can be made to the prior art.

[0068] In some preferred embodiments of the present application, the back contact photovoltaic cell further comprises: a conductive film layer disposed on the outer surface of the N-type doped region and the P-type doped region, and a metal electrode disposed on the outer surface of the conductive film layer, wherein an isolation groove is disposed between the conductive film layer disposed on the outer surface of the N-type doped region and the conductive film layer disposed on the outer surface of the P-type doped region, and at least part of the isolation groove is located on the outer surface of the co-doped region.

[0069] The light-receiving surface and the back surface of the silicon substrate of the present application can each be a textured surface or a polished surface. In some preferred embodiments of the present application, the light-receiving surface of the silicon substrate is a textured surface, and the back surface is a polished surface.

[0070] In a second aspect, the present application provides a preparation method of a back contact photovoltaic cell for preparing the back contact photovoltaic cell with a high-concentration co-doped region of the first aspect, which comprises the following steps:

[0071] S1, providing a silicon substrate;

[0072] S2, depositing an intrinsic amorphous silicon layer on the back surface of the silicon substrate;

[0073] S3, predefining an N-type doped region, a P-type doped region and a co-doped region between the N-type doped region and the P-type doped region in an alternating distribution on the outer surface of the intrinsic amorphous silicon layer;

[0074] The N-type doped region, the P-type doped region and the co-doped region are formed in each of the predefined regions by using a template method; wherein the doping concentration of phosphorus contained in the co-doped region is greater than the doping concentration of phosphorus in the N-type doped region, and the doping concentration of boron contained in the co-doped region is greater than the doping concentration of boron in the P-type doped region, thereby forming a specific concentration gradient structure.

[0075] The predefining an N-type doped region, a P-type doped region and a co-doped region between the N-type doped region and the P-type doped region in an alternating distribution on the outer surface of the intrinsic amorphous silicon layer means that three regions are divided at the positions where the N-type doped region, the P-type doped region and the co-doped region are to be disposed, thereby facilitating the subsequent steps.

[0076] The forming of the N-type doped region, the P-type doped region and the co-doped region can be by doping part of the regions of the intrinsic amorphous silicon layer, or by depositing a new film layer on the outer surface of the intrinsic amorphous silicon layer.

[0077] In some preferred embodiments of the present application, the process of forming the N-type doped region, the P-type doped region and the co-doped region in each preset region by using the template method comprises: performing ion doping of target doping ions in each preset region by using the template method, so as to form the N-type doped region, the P-type doped region and the co-doped region, respectively. Specifically, the intrinsic amorphous silicon layer can be formed first, and then the ion doping can be performed in the regions not covered by the template. Alternatively, the template can be used to mask the non-target doped regions, so as to form the N-type doped region, the P-type doped region and the co-doped region, respectively. The specific doping method can refer to the prior art, as long as the target structure film layer of the present application is obtained, and thus will not be described herein.

[0078] In some specific preferred embodiments of the present application, the process of forming the N-type doped region, the P-type doped region and the co-doped region in each preset region by using the template method comprises: first, using a first hard mask to shield the preset P-type doped region and the preset co-doped region on the back surface, growing the N-type doped silicon of the target thickness on the back surface to form the N-type doped region; then, using a second hard mask to shield the preset N-type doped region and the preset co-doped region on the back surface, growing the P-type doped silicon of the target thickness to form the P-type doped region; finally, using a third hard mask to shield the N-type doped region and the P-type doped region, growing the co-doped region of the target thickness.

[0079] In some preferred embodiments of the present application, the preparation method further comprises: S4, depositing a conductive film layer on the outer surface of the intrinsic amorphous layer after the doping in S3, and opening and forming an isolation groove on at least part of the conductive film layer located on the outer surface of the co-doped region.

[0080] The preparation method of the present application can also include the preparation of other conventional film layers. In some preferred embodiments of the present application, S5, a metal electrode is formed on the outer surface of the conductive film layer in the regions corresponding to the N-type doped region and the P-type doped region, respectively.

[0081] Compared with the complex preparation process of the existing heterojunction structure, the technical solution of the present application simplifies the preparation process, reduces the production cost, and is conducive to large-scale application. At the same time, the conversion efficiency of the battery is improved.

[0082] In a third aspect, the present application provides a photovoltaic module comprising the back contact photovoltaic cell with the high-concentration co-doped region according to the first aspect, or the back contact photovoltaic cell prepared by the preparation method of the back contact photovoltaic cell according to the second aspect.

[0083] The embodiments of the present application are described in detail below, which are exemplary and only used to explain the present application, and cannot be understood as a limitation of the present application.

[0084] Embodiment 1

[0085] A back contact photovoltaic cell has a structure asFigure 1 As shown, specifically comprising the following steps:

[0086] S1, providing a silicon substrate 1;

[0087] S2, depositing an intrinsic amorphous silicon layer 2 with a thickness of 13 nm on the back surface of the silicon substrate 1;

[0088] S3, presetting an alternating distribution of N-type doped regions 3, P-type doped regions 4 and co-doped regions 5 between the N-type doped regions 3 and the P-type doped regions 4 on the outer surface of the intrinsic amorphous silicon layer 2;

[0089] Doping the target doped ions in each preset region by using a template method to form the N-type doped regions 3, the P-type doped regions 4 and the co-doped regions 5; wherein, in the process of forming the target doped regions, the other non-target doped regions are first masked and then doped, and thus the N-type doped regions 3, the P-type doped regions 4 and the co-doped regions 5 are sequentially formed. Among them, the doping concentration of phosphorus contained in the co-doped region 5 is greater than the phosphorus doping concentration in the N-type doped region 3, and the doping concentration of boron contained in the co-doped region 5 is greater than the boron doping concentration in the P-type doped region 4, forming a specific concentration gradient structure. Among them, the phosphorus doping concentration and the boron doping concentration contained in the co-doped region 5 are respectively 1e22cm -3 , 9.2e21cm -3 , and the hydrogen doping concentration is 5e21cm -3 ; the width of the co-doped region 5 is 20μm, and the thickness is 6nm. The phosphorus doping concentration in the N-type doped region 3 is 7e21cm -3 , the hydrogen doping concentration is 4e21cm -3 , the width is 300μm, and the thickness is 7nm. The boron doping concentration in the P-type doped region 4 is 5e21cm -3 , the hydrogen doping concentration is 5e21cm -3 , the width is 500μm, and the thickness is 10nm. It is calculated that the ratio of the doping concentration of phosphorus contained in the co-doped region 5 to the phosphorus doping concentration in the N-type doped region 3 is 1.4:1, the ratio of the doping concentration of boron contained in the co-doped region 5 to the boron doping concentration in the P-type doped region 4 is 1.8:1; the ratio of the hydrogen doping concentration in the co-doped region 5 to the hydrogen doping concentration in the N-type doped region 3 is 1.25:1, and the ratio of the hydrogen doping concentration in the co-doped region 5 to the hydrogen doping concentration in the P-type doped region 4 is 1:1.

[0090] S4, using a template method to mask the outer surface of the co-doped region 5, and then depositing a transparent conductive film layer 6 (i.e. ITO) with a thickness of 60nm on the outer surface of the intrinsic amorphous layer after doping in S3, and forming an isolation groove 7 in the masked area;

[0091] S5, forming metal electrodes 8 on the outer surface of the conductive film layer 6 in the regions corresponding to the N-type doped region 3 and the P-type doped region 4, respectively.

[0092] Example 2

[0093] Example 1 was followed except that the doping concentration of phosphorus contained in the co-doped region 5 was adjusted to 2e22cm -3 so that the ratio of the doping concentration of phosphorus contained in the co-doped region 5 to the doping concentration of phosphorus in the N-type doped region 3 was 2.8: 1.

[0094] Example 3

[0095] Example 1 was followed except that the doping concentration of boron contained in the co-doped region 5 was adjusted to 1.5e22cm -3 so that the ratio of the doping concentration of boron contained in the co-doped region 5 to the doping concentration of boron in the P-type doped region 4 was 3: 1.

[0096] Example 4

[0097] Example 1 was followed except that the doping concentration of H contained in the co-doped region 5 was adjusted to 4e21cm -3 so that the ratio of the doping concentration of H contained in the co-doped region 5 to the doping concentration of H in the N-type doped region 3, P-type doped region 4 was 1: 1, 0.8: 1, respectively.

[0098] Example 5

[0099] Example 1 was followed except that the doping concentration of H contained in the co-doped region 5 was adjusted to 6e21cm -3 so that the ratio of the doping concentration of H contained in the co-doped region 5 to the doping concentration of H in the N-type doped region 3, P-type doped region 4 was 1.5: 1, 1.2: 1, respectively.

[0100] Example 6

[0101] Example 1 was followed except that the width of the co-doped region 5 was adjusted to 30 μm so that the ratio of the width of the co-doped region 5 to the N-type doped region 3, P-type doped region 4 was 0.1: 1, 0.06: 1, respectively.

[0102] Comparative Example 1

[0103] Example 1 was followed except that the doping concentration of phosphorus contained in the co-doped region 5 was adjusted to 6e21cm -3 so that the ratio of the doping concentration of phosphorus contained in the co-doped region 5 to the doping concentration of phosphorus in the N-type doped region 3 was 0.86: 1.

[0104] Comparative Example 2

[0105] Example 1 was followed except that the doping concentration of boron contained in the co-doped region 5 was adjusted to 5e21cm -3The ratio of the doping concentration of boron contained in the co-doped region 5 to the doping concentration of boron in the P-type doped region 4 is 1:1.

[0106] Test Example

[0107] The back contact photovoltaic cells obtained in the above examples and comparative examples were tested for performance, and the results are shown in Table 1.

[0108] Table 1

[0109] Performance metrics Open circuit voltage (V) Fill factor (%) Cell conversion efficiency (%) Reverse leakage current (A) Example 1 0.7483 85.6 27.16 0.08 Example 2 0.7477 85.3 27.08 0.10 Example 3 0.7472 85.3 27.02 0.13 Example 4 0.7465 85.4 27.05 0.11 Example 5 0.7474 85.2 27.00 0.09 Example 6 0.7479 85.3 27.05 0.10 Comparative Example 1 0.7462 85.1 26.90 0.15 Comparative Example 2 0.7460 84.9 26.85 0.16

[0110] From the above results, it can be seen that, compared with the comparative examples, the embodiment scheme of the present application is beneficial to improve the fill factor and open circuit voltage, and improve the conversion efficiency and stability of the cell.

[0111] Further, according to Examples 1 and 2-6, the preferred scheme of the present application is more beneficial to improve the fill factor and open circuit voltage, and improve the conversion efficiency and stability of the cell.

[0112] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical scheme of the present application, including the combination of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A back contact photovoltaic cell having a high concentration co-doped region, characterized in that, The back contact photovoltaic cell comprises a silicon substrate, an intrinsic amorphous silicon layer arranged on the back light surface of the silicon substrate, and N-type doped regions and P-type doped regions arranged alternately on the back light surface of the intrinsic amorphous silicon layer, and a high-concentration co-doped region arranged between the N-type doped regions and the P-type doped regions, wherein the doping source of the co-doped region comprises phosphorus as the doping source of the N-type doped regions and boron as the doping source of the P-type doped regions, the co-doped region and the N-type doped regions and the P-type doped regions form a specific concentration gradient structure, and the specific concentration gradient structure satisfies that the doping concentration of phosphorus contained in the co-doped region is greater than the doping concentration of phosphorus in the N-type doped regions, and the doping concentration of boron contained in the co-doped region is greater than the doping concentration of boron in the P-type doped regions.

2. The back contact photovoltaic cell with high concentration co-doped regions of claim 1, wherein, The ratio of the highest doping concentration of phosphorus contained in the co-doped region to the highest doping concentration of phosphorus in the N-type doped regions is (1.1-10):1, and / or the ratio of the highest doping concentration of boron contained in the co-doped region to the highest doping concentration of boron in the P-type doped regions is (1.05-8):

1.

3. The back contact photovoltaic cell with high concentration co-doped regions of claim 2, wherein, The ratio of the highest doping concentration of phosphorus contained in the co-doped region to the highest doping concentration of phosphorus in the N-type doped regions is (1.3-5):1, and / or the ratio of the highest doping concentration of boron contained in the co-doped region to the highest doping concentration of boron in the P-type doped regions is (1.2-3.5):

1.

4. Back contact photovoltaic cell with high concentration co-doped regions according to any of claims 1-3, characterized in that, the phosphorus doping concentration, the boron doping concentration in the co-doped region each independently is in the range of 2e19cm-5e23cm -3 -5e23cm -3 ; and / or, The phosphorus doping concentration in the N-type doped region is 2e18cm -3 -8e22cm -3 The boron doping concentration in the P-type doped region is 2e18cm -3 -8e22cm -3 .

5. Back contact photovoltaic cell with high concentration co-doped regions according to any of claims 1-3, characterized in that, The co-doped region is hydrogen-doped, and the hydrogen doping concentration in the co-doped region is higher than the hydrogen doping concentration in the N-type doped regions and / or the P-type doped regions.

6. The back contact photovoltaic cell with high concentration co-doped regions of claim 5, wherein, the ratio of the hydrogen doping concentration in the co-doped region to the hydrogen doping concentration in the N-type doped region or the P-type doped region is (0.5-3): 1, and / or the hydrogen doping concentration of the co-doped region is 1e19cm -3 -5e22cm -3 .

7. Back contact photovoltaic cell with high concentration co-doped regions according to any of claims 1-3, characterized in that, The back contact photovoltaic cell further has at least one of the following structures: Structure one: the ratio of the width of the co-doped region to the width of the N-type doped regions or the P-type doped regions is (0.01-0.4):1, and / or the ratio of the thickness of the co-doped region to the thickness of the N-type doped regions or the P-type doped regions is (0.5-1.4):1; Structure two: the width of the co-doped region is 5-130 μm, and / or the thickness of the co-doped region is 5-30 nm; Structure three: the width of each of the N-type doped regions and the P-type doped regions is independently 200-1000 μm, and / or the thickness of each of the N-type doped regions and the P-type doped regions is independently 5-20 nm; Structure four: the thickness of the intrinsic amorphous silicon layer is 5-15 nm, and / or the ratio of the thickness of the intrinsic amorphous silicon layer to the thickness of the N-type doped regions or the P-type doped regions is (0.3-2):1; Structure five: in the width direction, the N-type doped regions and the co-doped region, and the co-doped region and the P-type doped regions are in contact with each other and are continuously distributed as a whole; Structure six: the N-type doped regions and the P-type doped regions are respectively formed by doping part of the intrinsic amorphous silicon layer, or are respectively formed by depositing a doped film layer on the back light surface of the intrinsic amorphous silicon layer; Structure seven: the back contact photovoltaic cell further comprises a light-receiving surface passivation and anti-reflection layer arranged on the light-receiving surface of the silicon substrate; Structure eight: the back contact photovoltaic cell further comprises: a conductive film layer arranged on the outer surface of the N-type doped regions and the P-type doped regions, and a metal electrode arranged outside the conductive film layer, wherein an isolation groove is arranged between the conductive film layer arranged on the outer surface of the N-type doped regions and the conductive film layer arranged on the outer surface of the P-type doped regions, and at least part of the isolation groove is located on the outer surface of the co-doped region; Structure nine: the light-receiving surface of the silicon substrate is a textured surface, and the back light surface is a polished surface.

8. A method of fabricating a back contact photovoltaic cell, characterized by, The back contact photovoltaic cell with high concentration co-doped region is prepared by the method comprising the following steps: S1, providing a silicon substrate; S2, depositing an intrinsic amorphous silicon layer on the back surface of the silicon substrate; S3, pre-setting N-type doped region, P-type doped region and co-doped region between the N-type doped region and the P-type doped region in an alternating distribution on the outer surface of the intrinsic amorphous silicon layer; The N-type doped region, the P-type doped region and the co-doped region are formed in the respective preset regions by using a template method; wherein the doping concentration of phosphorus contained in the co-doped region is greater than the doping concentration of phosphorus in the N-type doped region, the doping concentration of boron contained in the co-doped region is greater than the doping concentration of boron in the P-type doped region, and a specific concentration gradient structure is formed.

9. The method of claim 8, wherein the back contact photovoltaic cell is formed by a process comprising: The preparation method further comprises at least one of the following processes: Process one, the N-type doped region, the P-type doped region and the co-doped region are formed in the respective preset regions by using a template method, and the process comprises: target doping ions are doped in the respective preset regions by using a template method, so as to form the N-type doped region, the P-type doped region and the co-doped region respectively; Process two, the preparation method further comprises: S4, depositing a conductive film layer on the outer surface of the intrinsic amorphous layer after the doping in S3, and opening and forming isolation grooves on at least part of the conductive film layer located on the outer surface of the co-doped region; S5, forming metal electrodes on the outer surfaces of the conductive film layers corresponding to the N-type doped region and the P-type doped region respectively.

10. A photovoltaic module, characterized by, The back contact photovoltaic cell with high concentration co-doped region is prepared by the method comprising the following steps:

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