A back contact battery capable of reducing LID and a preparation method and battery assembly thereof

Abstract

The present invention belongs to the technical field of back contact batteries, and specifically relates to a back contact battery capable of reducing LID, a preparation method thereof, and a battery assembly, comprising a silicon wafer, a light-receiving surface passivation layer and an anti-reflection layer sequentially arranged on the light-receiving surface of the silicon wafer, the light-receiving surface passivation layer comprising a first tunneling oxide layer and a hydrogen-doped and carbon-doped silicon layer sequentially arranged, and the silicon layer is amorphous silicon or polycrystalline silicon; the anti-reflection layer comprises a hydrogen-doped silicon carbide film layer, the hydrogen-doped silicon carbide film layer comprises a first hydrogen-doped silicon carbide layer and a second hydrogen-doped silicon carbide layer sequentially arranged, the carbon doping concentration of the first hydrogen-doped silicon carbide layer is less than the carbon doping concentration of the second hydrogen-doped silicon carbide layer, the thickness of the first hydrogen-doped silicon carbide layer is 10-30nm, and the thickness of the second hydrogen-doped silicon carbide layer is 50-100nm. The present invention can take into account the passivation effect, the optical effect, and the LID anti-attenuation capability, and is conducive to reducing the LID, improving the battery stability, and improving the battery reliability.

Description

Technical Field

[0001] The present invention belongs to the technical field of back contact batteries, and in particular relates to a back contact battery capable of reducing LID, a preparation method thereof, and a battery assembly. Background Art

[0002] The conversion efficiency of back-contact cells is gradually improving. While achieving high conversion efficiency, it is also necessary to consider how to ensure that the cells maintain high conversion efficiency when actually working outdoors. Therefore, in addition to conversion efficiency, reliability has also become a key factor in measuring the quality of crystalline silicon solar cells and modules. As an upstream product, the reliability of solar cells is bound to affect downstream products such as modules and power stations, and the impact is gradually expanding.

[0003] LID, or light-induced degradation, is one of the indicators for testing the reliability of solar cells. The LID phenomenon is that when a battery is placed under sunlight for an irradiation experiment, the battery's power generation power, short-circuit current, and open-circuit voltage will decay exponentially and reach a stable state after 12 hours of irradiation.

[0004] At present, back-contact batteries have certain LID conditions, and it is necessary to reduce LID, improve stability, and improve reliability.

[0005] It should be noted that this part of the present invention only provides background technology related to the present invention and does not necessarily constitute prior art or known technology. Summary of the invention

[0006] The purpose of the present invention is to overcome the defects of the prior art of back-contact batteries, such as obvious LID and poor stability, and to provide a back-contact battery that can reduce LID, a preparation method thereof, and a battery assembly, which can take into account the passivation effect, optical effect, and LID anti-attenuation ability, and is conducive to reducing LID, improving battery stability, and improving battery reliability.

[0007] In order to achieve the above-mentioned purpose, in a first aspect, the present invention provides a back contact battery capable of reducing LID, comprising a silicon wafer, a light-receiving surface passivation layer and an anti-reflection layer sequentially arranged on the light-receiving surface of the silicon wafer, the light-receiving surface passivation layer comprising a first tunneling oxide layer and a hydrogen-doped and carbon-doped silicon layer sequentially arranged, and the silicon layer is amorphous silicon or polycrystalline silicon; the anti-reflection layer comprises a hydrogen-doped silicon carbide film layer, the hydrogen-doped silicon carbide film layer comprises a first hydrogen-doped silicon carbide layer and a second hydrogen-doped silicon carbide layer sequentially arranged, the carbon doping concentration of the first hydrogen-doped silicon carbide layer is less than the carbon doping concentration of the second hydrogen-doped silicon carbide layer, the thickness of the first hydrogen-doped silicon carbide layer is 10-30nm, the thickness of the second hydrogen-doped silicon carbide layer is 50-100nm, preferably 70-100nm, and the ratio of the hydrogen doping concentration in the hydrogen-doped and carbon-doped silicon layer to the hydrogen doping concentration in the first hydrogen-doped silicon carbide layer is 1:(1-10).

[0008] In some preferred embodiments of the present invention, the carbon doping concentration of the first hydrogen-doped silicon carbide layer is 1×10 18 cm -3 -9×10 19 cm -3 .

[0009] In some preferred embodiments of the present invention, the carbon doping concentration of the second hydrogen-doped silicon carbide layer is 1×10 19 cm -3 -9×10 20 cm -3 .

[0010] In some preferred embodiments of the present invention, the ratio of the carbon doping concentration of the first hydrogen-doped silicon carbide layer to the carbon doping concentration of the second hydrogen-doped silicon carbide layer is 1:(0.5-650), and the unit of the carbon doping concentration is cm -3 .

[0011] In some preferred embodiments of the present invention, the total thickness of the anti-reflection layer is 70-130 nm, preferably 80-130 nm.

[0012] In some preferred embodiments of the present invention, the thickness ratio of the first hydrogen-doped silicon carbide layer to the second hydrogen-doped silicon carbide layer is 1:(1.7-10).

[0013] In some preferred embodiments of the present invention, the refractive index of the first hydrogen-doped silicon carbide layer is 2.0-2.2, and the refractive index of the second hydrogen-doped silicon carbide layer is 1.93-2.08.

[0014] In some preferred embodiments of the present invention, the refractive index of the first hydrogen-doped silicon carbide layer is greater than the refractive index of the second hydrogen-doped silicon carbide layer.

[0015] In some preferred embodiments of the present invention, the hydrogen doping concentration of the first hydrogen doped silicon carbide layer is 1×10 21 cm -3 -6×10 22 cm -3 .

[0016] In some preferred embodiments of the present invention, the hydrogen doping concentration of the second hydrogen-doped silicon carbide layer is 1×10 21 cm -3 -6×10 22 cm -3 .

[0017] In some preferred embodiments of the present invention, the ratio of the hydrogen doping concentration of the first hydrogen doped silicon carbide layer to the hydrogen doped silicon carbide layer is 1:(0.1-60).

[0018] In some preferred embodiments of the present invention, the hydrogen doping concentration in the hydrogen-doped and carbon-doped silicon layer is 1×1020 cm -3 -9×10 21 cm -3 .

[0019] In some preferred embodiments of the present invention, the carbon doping concentration in the hydrogen-doped and carbon-doped silicon layer is 1×10 18 cm -3 -3.3×10 19 cm -3 .

[0020] In some preferred embodiments of the present invention, the thickness of the hydrogen-doped and carbon-doped silicon layer is 6-18 nm.

[0021] In some preferred embodiments of the present invention, the thickness ratio of the hydrogen-doped silicon carbide film layer to the hydrogen-doped and carbon-doped silicon layer is (4.5-20):1.

[0022] In some preferred embodiments of the present invention, the hydrogen-doped and carbon-doped silicon layer is hydrogen-doped and carbon-doped amorphous silicon.

[0023] In some preferred embodiments of the present invention, the refractive index of the hydrogen-doped and carbon-doped silicon layer is 2.0-3.1, preferably 2.0-3.0.

[0024] In some preferred embodiments of the present invention, the back-contact battery capable of reducing LID also includes a first semiconductor layer and a second semiconductor layer alternately arranged on the back side of the silicon wafer, the first semiconductor layer includes a first passivation layer and a first doped silicon layer, the second semiconductor layer includes a second passivation layer and a second doped silicon layer, the first passivation layer and the second passivation layer are each independently a second tunneling oxide layer or an intrinsic silicon layer, and the first doped silicon layer and the second doped silicon layer are each independently doped polycrystalline silicon, doped amorphous silicon or doped microcrystalline silicon.

[0025] Preferably, the first doped silicon layer is thickened to 80-150 nm, and the second doped silicon layer is thickened to 5-15 nm.

[0026] In some preferred embodiments of the present invention, the back contact cell capable of reducing LID further comprises at least one of the following structures:

[0027] Structure 1: The first passivation layer is a second tunneling oxide layer, the first doped silicon layer is doped polycrystalline silicon, the second passivation layer is an intrinsic silicon layer, and the second doped silicon layer is doped amorphous silicon or doped microcrystalline silicon;

[0028] Structure 2: Both ends of the second semiconductor layer extend outward to cover the back side of the adjacent first semiconductor layer, and a first semiconductor opening region not covering the second semiconductor layer is provided on the back side of the first semiconductor layer, a second semiconductor opening region is formed between adjacent first semiconductor layers, the second semiconductor opening region is arranged at intervals from the first semiconductor opening region, and the region between them is a spacing region; in the spacing region, an isolation layer is provided between the first semiconductor layer and the second semiconductor layer, or no isolation layer is provided; the back contact battery capable of reducing LID further comprises a metal electrode and a conductive film layer laid on the outer surfaces of the first semiconductor layer and the second semiconductor layer, an isolation groove is provided on the portion of the conductive film layer located in the spacing region; the metal electrode is provided on the outer surfaces of the conductive film layers corresponding to the second semiconductor opening region and the first semiconductor opening region;

[0029] Structure 3: The second semiconductor layer attachment area on the back of the silicon wafer and the light-receiving surface of the silicon wafer are respectively the textured surfaces, and the first semiconductor layer attachment area on the back of the silicon wafer is the polished surface;

[0030] Structure 4: The thickness of the first tunneling oxide layer is 1-2 nm.

[0031] In a second aspect, the present invention provides a method for preparing a back contact battery capable of reducing LID, which is used to prepare the back contact battery capable of reducing LID as described in the first aspect, and the preparation method comprises the following steps:

[0032] A light-receiving surface passivation layer including a first tunneling oxide layer and a hydrogen-doped and carbon-doped silicon layer is sequentially deposited on the light-receiving surface of the silicon wafer, and then an anti-reflection layer including a first hydrogen-doped silicon carbide layer and a second hydrogen-doped silicon carbide layer is continuously deposited on the light-receiving surface.

[0033] In some preferred embodiments of the present invention, during the deposition of the hydrogen-doped and carbon-doped silicon layer, the flow rate ratio of silane, methane and hydrogen is controlled to be 1: (0.5-9): (3-20).

[0034] In some preferred embodiments of the present invention, the flow rate of methane introduced during the deposition of the first hydrogen-doped silicon carbide layer is controlled to be 480-2000 sccm, and the flow rate of methane introduced during the deposition of the second hydrogen-doped silicon carbide layer is controlled to be 2050-10000 sccm, further preferably 2200-10000 sccm, and preferably 4000-10000 sccm.

[0035] In some preferred embodiments of the present invention, the flow rate of silane during the deposition of the hydrogen-doped and carbon-doped silicon layer is 800-2000 sccm.

[0036] In some preferred embodiments of the present invention, the deposition conditions of the hydrogen-doped and carbon-doped silicon layer include: deposition temperature of 350-600°C, hydrogen flow rate of 2000-30000sccm, methane flow rate of 800-15000sccm, deposition pressure of 1300-3000mtorr, and power of 2kw-10kw.

[0037] In some preferred embodiments of the present invention, the deposition conditions of the first hydrogen-doped silicon carbide layer and the second hydrogen-doped silicon carbide layer independently include: a deposition temperature of 350-600°C, a silane flow rate of 800-2000sccm, a hydrogen flow rate of 2000-8000sccm, and a deposition pressure of 1300-2500mtorr; and the deposition power of the first hydrogen-doped silicon carbide layer is 3kw-15kw, and the deposition power of the second hydrogen-doped silicon carbide layer is 5kw-20kw.

[0038] In some preferred embodiments of the present invention, the hydrogen-doped and carbon-doped silicon layer, the first hydrogen-doped silicon carbide layer, and the second hydrogen-doped silicon carbide layer are all deposited using tubular PECVD equipment.

[0039] In some preferred embodiments of the present invention, the method for preparing a back contact battery capable of reducing LID further comprises:

[0040] A first semiconductor layer is formed on the back of the silicon wafer, and then a second semiconductor opening area is formed; then a texturing cleaning is performed to form a texturing surface on the light-receiving surface of the silicon wafer and the second semiconductor opening area; then a target film layer is deposited on the light-receiving surface of the silicon wafer, and then a second semiconductor layer is deposited on the back, and then a first semiconductor opening area arranged alternately with the second semiconductor opening area is formed on part of the second semiconductor layer;

[0041] A conductive film layer is deposited on the obtained back side, and an isolation groove is formed on a portion of the conductive film layer located between the first semiconductor opening area and the second semiconductor opening area; then metal electrodes are formed on the outer surfaces of the corresponding conductive film layers in the areas where the first semiconductor opening area and the second semiconductor opening area are located.

[0042] In a third aspect, the present invention provides a battery assembly, which includes the back contact battery capable of reducing LID as described in the first aspect.

[0043] Beneficial effects:

[0044] The present invention adopts the above-mentioned technical scheme, especially adopts a specific light-receiving surface passivation layer and an anti-reflection layer, wherein the hydrogen-doped and carbon-doped silicon layer and the hydrogen-doped silicon carbide film layer are doped with hydrogen and carbon respectively, which is beneficial to improving the density of the film layer and reducing the defect density of the film layer. The hydrogen-doped silicon carbide film layer is beneficial to improving the stability and consistency of the process and improving the production yield; the hydrogen-doped silicon carbide film layer and the hydrogen-doped and carbon-doped silicon layer with a suitable hydrogen doping concentration ratio are combined to improve the density and passivation effect of the film layer; and the carbon doping concentration of the first hydrogen-doped silicon carbide layer is controlled to be less than the carbon doping concentration of the second hydrogen-doped silicon carbide layer, which is beneficial to taking into account the passivation effect, optical effect and LID anti-attenuation ability, and is beneficial to improving the battery stability; thereby synergistically reducing LID, improving battery stability, and improving battery reliability.

[0045] The present invention also specifically controls the first hydrogen-doped silicon carbide layer to be at a suitable low thickness and the second hydrogen-doped silicon carbide layer to be at a suitable high thickness, which is beneficial to taking into account both the passivation effect and the optical effect, and controls the silicon layer in the hydrogen-doped and carbon-doped silicon layer to be amorphous silicon or polycrystalline silicon, which cooperates with the first tunneling oxide layer, which is beneficial to improving the passivation effect while reducing parasitic absorption and increasing the current density.

[0046] In the preparation method of the present invention, when depositing the light-receiving surface passivation layer, adding hydrogen and methane in an appropriate flow ratio is beneficial to improving the density and optical effect of the film layer, and during the deposition process, hydrogen reacts with silane, and the film grown by the high hydrogen dilution method has good order and low anisotropic nano-level defect density; and a certain appropriate ratio of methane is added to the film layer of the light-receiving surface passivation layer, and the decomposed carbon bonds in the methane are combined with silicon bonds to improve the density of the film layer and reduce the content of unstable hydrogen bonds in the film layer, thereby helping to improve the stability of the back contact battery during light exposure; when depositing the anti-reflection layer, the conventional silicon nitride film is replaced by a hydrogen-doped silicon carbide layer to further improve the stability of the film layer; thereby reducing LID, improving stability, and improving reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0048] Figure 1 It is a schematic structural diagram of a specific embodiment of the back contact battery of the present invention.

[0049] Description of Reference Numerals

[0050] Silicon wafer 1, second tunneling silicon oxide layer 2, N-type doped polysilicon layer 3, first tunneling oxide layer 5, hydrogen-doped carbon-doped silicon layer 6, anti-reflection layer 7, low-carbon-doped hydrogen-doped silicon carbide layer 7.1, high-carbon-doped hydrogen-doped silicon carbide layer 7.2, intrinsic hydrogenated amorphous silicon layer 8, P-type doped amorphous silicon layer 9, conductive film layer 10, and metal electrode 11. DETAILED DESCRIPTION

[0051] In the present invention, unless otherwise specified, directional words such as "upper, lower, left, right" are generally understood in conjunction with the directions shown in the drawings and actual applications.

[0052] 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 one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0053] In the present invention, 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 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.

[0054] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article. Among them, the terms "optional" and "optional" all mean that they may be included or not included (or may be present or not).

[0055] In the present invention, the area close to the silicon wafer is referred to as the inside, and the area far from the silicon wafer is referred to as the outside.

[0056] In a first aspect, the present invention provides a back contact battery capable of reducing LID, comprising a silicon wafer, a light-receiving surface passivation layer and an anti-reflection layer sequentially arranged on a light-receiving surface of the silicon wafer, the light-receiving surface passivation layer comprising a first tunneling oxide layer and a hydrogen-doped and carbon-doped silicon layer sequentially arranged, the silicon layer being amorphous silicon or polycrystalline silicon; the anti-reflection layer comprising a hydrogen-doped silicon carbide film layer, the hydrogen-doped silicon carbide film layer comprising a first hydrogen-doped silicon carbide layer and a second hydrogen-doped silicon carbide layer sequentially arranged, the carbon doping concentration of the first hydrogen-doped silicon carbide layer being less than the carbon doping concentration of the second hydrogen-doped silicon carbide layer, the thickness of the first hydrogen-doped silicon carbide layer being 10-30 nm, the thickness of the second hydrogen-doped silicon carbide layer being 50-100 nm, preferably 70-100 nm, and the ratio of the hydrogen doping concentration in the hydrogen-doped and carbon-doped silicon layer to the hydrogen doping concentration in the first hydrogen-doped silicon carbide layer being 1:(1-10), and the ratio of the hydrogen doping concentration in the hydrogen-doped and carbon-doped silicon layer to the hydrogen doping concentration in the second hydrogen-doped silicon carbide layer being 1:(1-16).

[0057] The ratio of the hydrogen doping concentration in the hydrogen-doped and carbon-doped silicon layer to the hydrogen doping concentration in the first hydrogen-doped silicon carbide layer is 1:(1-10), and specifically can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10 and the range between any two point values, preferably 1:(1.5-10), and further preferably 1:(1.5-9).

[0058] The ratio of the hydrogen doping concentration in the hydrogen-doped and carbon-doped silicon layer to the hydrogen doping concentration in the second hydrogen-doped silicon carbide layer is 1:(1-16), and specifically can be 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:15, 1:16 and the range between any two point values, preferably 1:(1.5-10).

[0059] The thickness of the first hydrogen-doped silicon carbide layer is 10-30 nm, for example, it can be 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, 15 nm, 16 nm, 17 nm, 18 nm, 19 nm, 20 nm, 21 nm, 22 nm, 23 nm, 24 nm, 25 nm, 26 nm, 27 nm, 28 nm, 29 nm, 30 nm and the range between any two point values.

[0060] The thickness of the second hydrogen-doped silicon carbide layer is 50-100 nm, for example, it can be 50 nm, 60 nm, 70 nm, 73 nm, 75 nm, 77 nm, 80 nm, 82 nm, 85 nm, 87 nm, 90 nm, 93 nm, 95 nm, 97 nm, 100 nm and the range between any two point values, preferably 70-100 nm.

[0061] In some preferred embodiments of the present invention, the carbon doping concentration of the first hydrogen-doped silicon carbide layer is 1×1018 cm -3 -9×10 19 cm -3 .

[0062] In some preferred embodiments of the present invention, the carbon doping concentration of the second hydrogen-doped silicon carbide layer is 1×10 19 cm -3 -9×10 20 cm -3 .

[0063] In the present invention, the first hydrogen-doped silicon carbide layer and the second hydrogen-doped silicon carbide layer with appropriate carbon doping concentration are used, which is more conducive to reducing the LID attenuation amplitude.

[0064] In some preferred embodiments of the present invention, the ratio of the carbon doping concentration of the first hydrogen-doped silicon carbide layer to the second hydrogen-doped silicon carbide layer is 1: (0.5-650), preferably 1: (1.2-650), further preferably 1: (1.2-100), and more preferably 1: (2.0-80), and the unit of the carbon doping concentration is cm -3 The adoption of this preferred solution is more conducive to improving the LID attenuation amplitude while ensuring the passivation effect.

[0065] In some preferred embodiments of the present invention, the total thickness of the anti-reflection layer is 70-130 nm, preferably 80-130 nm, which is more conducive to reducing optical absorption.

[0066] In some preferred embodiments of the present invention, the thickness ratio of the first hydrogen-doped silicon carbide layer to the second hydrogen-doped silicon carbide layer is 1:(1.7-10), preferably 1:(2.8-10). Controlling the appropriate thickness ratio of the first hydrogen-doped silicon carbide layer and the second hydrogen-doped silicon carbide layer is more conducive to taking into account both optical effect and LID effect.

[0067] In some preferred embodiments of the present invention, the refractive index of the first hydrogen-doped silicon carbide layer is 2.0-2.2, and the refractive index of the second hydrogen-doped silicon carbide layer is 1.93-2.08, preferably 1.95-2.0. The refractive index of the first hydrogen-doped silicon carbide layer and the second hydrogen-doped silicon carbide layer is controlled within a suitable range, which is more conducive to improving the anti-reflection effect of the film layer.

[0068] In some preferred embodiments of the present invention, the refractive index of the first hydrogen-doped silicon carbide layer is greater than the refractive index of the second hydrogen-doped silicon carbide layer, which is more conducive to controlling the anti-reflection effect of the film layer.

[0069] In some preferred embodiments of the present invention, the hydrogen doping concentration of the first hydrogen doped silicon carbide layer is 1×10 21 cm -3 -6×10 22 cm -3 .

[0070] In some preferred embodiments of the present invention, the hydrogen doping concentration of the second hydrogen-doped silicon carbide layer is 1×10 21 cm -3 -6×10 22 cm -3 .

[0071] In the present invention, the hydrogen doping concentrations of the first hydrogen-doped silicon carbide layer and the second hydrogen-doped silicon carbide layer may be the same or different. The hydrogen doping concentrations thereof are controlled within the above-mentioned suitable range, which is more conducive to improving the compactness of the film layer.

[0072] In some preferred embodiments of the present invention, the ratio of the hydrogen doping concentration of the first hydrogen doped silicon carbide layer to the hydrogen doped silicon carbide layer is 1:(0.1-60), which is more conducive to taking into account both the compactness and the passivation effect of the film layer.

[0073] In some preferred embodiments of the present invention, the hydrogen doping concentration in the hydrogen-doped and carbon-doped silicon layer is 1×10 20 cm -3 -9×10 21 cm -3 .

[0074] In some preferred embodiments of the present invention, the carbon doping concentration in the hydrogen-doped and carbon-doped silicon layer is 1×10 18 cm -3 -3.3×10 19 cm -3 .

[0075] The hydrogen-doped and carbon-doped silicon layer adopts a carbon doping concentration and a hydrogen doping concentration within an appropriate range, which is more conducive to improving the overall battery performance and controlling LID attenuation.

[0076] In some preferred embodiments of the present invention, the thickness of the hydrogen-doped and carbon-doped silicon layer is 6-18 nm.

[0077] In some preferred embodiments of the present invention, the thickness ratio of the hydrogen-doped silicon carbide film layer to the hydrogen-doped and carbon-doped silicon layer is (4.5-20):1, preferably (7.0-20):1, which is more conducive to improving the passivation effect and the stability of the film layer.

[0078] In some preferred embodiments of the present invention, the hydrogen-doped and carbon-doped silicon layer is hydrogen-doped and carbon-doped amorphous silicon, which is more conducive to achieving both passivation effect and reducing parasitic absorption.

[0079] In some preferred embodiments of the present invention, the refractive index of the hydrogen-doped and carbon-doped silicon layer is 2.0-3.1, preferably 2.0-3.0.

[0080] In some preferred embodiments of the present invention, the thickness of the first tunnel oxide layer is 1-2 nm.

[0081] In some preferred embodiments of the present invention, the back contact cell capable of reducing LID further comprises a first semiconductor layer and a second semiconductor layer alternately arranged on the back of the silicon wafer, the first semiconductor layer comprises a first passivation layer and a first doped silicon layer, the second semiconductor layer comprises a second passivation layer and a second doped silicon layer, the first passivation layer and the second passivation layer are each independently a second tunneling oxide layer or an intrinsic silicon layer, and the first doped silicon layer and the second doped silicon layer are each independently doped polycrystalline silicon, doped amorphous silicon or doped microcrystalline silicon. The thickness of the first passivation layer and the first doped silicon layer, the second passivation layer and the second doped silicon layer and the corresponding doping concentration can refer to the ranges in the prior art, respectively.

[0082] In some preferred embodiments of the present invention, the first passivation layer is a second tunneling oxide layer, the first doped silicon layer is doped polycrystalline silicon, the second passivation layer is an intrinsic silicon layer, and the second doped silicon layer is doped amorphous silicon or doped microcrystalline silicon. The intrinsic silicon layer can be, for example, intrinsic amorphous silicon, intrinsic hydrogenated amorphous silicon, etc. The use of a combined passivation structure, in conjunction with the specific light-receiving surface passivation layer and the anti-reflection layer of the present invention, is more conducive to improving the conversion efficiency and stability of the battery.

[0083] More preferably, the first doped silicon layer is thickened to 80-150nm, and the second doped silicon layer is thickened to 5-15nm. Since the light-receiving passivation layer and the anti-reflection layer are doped with methane, the cleaning time from the front side to the back side film layer needs to be slightly extended. The preferred solution slightly increases the thickness of the back side film layer to help avoid cleaning losses.

[0084] More preferably, the thickness of the second tunnel oxide layer is 1-2 nm, and the effective doping concentration of the doped polysilicon is 2×10 18 cm -3 -5×10 20 cm -3 ; The thickness of the intrinsic silicon layer is 3-10 nm; The effective doping concentration of the second doped silicon layer is 2×10 18 cm -3 -10×10 19 cm -3 .

[0085] In some preferred embodiments of the present invention, both ends of the second semiconductor layer extend outward to cover part of the back side of the adjacent first semiconductor layer, and a first semiconductor opening region that does not cover the second semiconductor layer is opened on the back side of the first semiconductor layer, and a second semiconductor opening region is formed between adjacent first semiconductor layers. The second semiconductor opening region is spaced apart from the first semiconductor opening region, and the area between them is a spacing region.

[0086] Preferably, the width W2 of the second semiconductor opening region is 400-600 μm, the width W1 of the first semiconductor opening region is 150-350 μm, and the width W3 of the isolation trench is 20-100 μm.

[0087] Further preferably, in the spacer region, an isolation layer is provided between the first semiconductor layer and the second semiconductor layer or no isolation layer is provided. The type and thickness of the isolation layer can refer to the range in the prior art, for example, the type can be at least one of silicon nitride, silicon oxide, silicon oxynitride, and nitrogen-containing polysilicon, preferably silicon nitride. The thickness of the isolation layer is 50-100 nm.

[0088] In some preferred embodiments of the present invention, the back-contact battery capable of reducing LID also includes a metal electrode and a conductive film layer laid on the outer surfaces of the first semiconductor layer and the second semiconductor layer, and an isolation groove is opened on the portion of the conductive film layer located in the spacing area; the metal electrode is arranged on the outer surfaces of the conductive film layers corresponding to the second semiconductor opening area and the first semiconductor opening area.

[0089] In some preferred embodiments of the present invention, the second semiconductor attachment area on the back of the silicon wafer and the light-receiving surface of the silicon wafer are respectively textured surfaces, and the first semiconductor layer attachment area on the back of the silicon wafer is a polished surface.

[0090] In a second aspect, the present invention provides a method for preparing a back-contact battery capable of reducing LID, which is used to prepare the back-contact battery capable of reducing LID as described in the first aspect, and the preparation method comprises the following steps: depositing a light-receiving surface passivation layer comprising a first tunneling oxide layer and a hydrogen-doped and carbon-doped silicon layer on the light-receiving surface of a silicon wafer in sequence, and then continuing to deposit an anti-reflection layer comprising a first hydrogen-doped silicon carbide layer and a second hydrogen-doped silicon carbide layer on the light-receiving surface.

[0091] In some preferred embodiments of the present invention, when depositing the hydrogen-doped and carbon-doped silicon layer, the flow rate ratio of silane, methane and hydrogen is controlled to be 1: (0.5-9): (3-20), which is beneficial to improving the density and optical effect of the film layer.

[0092] In some preferred embodiments of the present invention, the flow rate of silane during the deposition of the hydrogen-doped and carbon-doped silicon layer is 800-2000 sccm.

[0093] In some preferred embodiments of the present invention, the deposition conditions of the hydrogen-doped and carbon-doped silicon layer include: a deposition temperature of 350-600°C.

[0094] In some preferred embodiments of the present invention, the deposition conditions of the hydrogen-doped and carbon-doped silicon layer include: a hydrogen flow rate of 2000-30000 sccm, and a methane flow rate of 800-15000 sccm.

[0095] In some preferred embodiments of the present invention, the deposition conditions of the hydrogen-doped and carbon-doped silicon layer include: a deposition pressure of 1300-3000 mtorr and a power of 2 kW-10 kW.

[0096] In some preferred embodiments of the present invention, the flow rate of methane introduced during the deposition of the first hydrogen-doped silicon carbide layer is controlled to be 480-2000sccm, and the flow rate of methane introduced during the deposition of the second hydrogen-doped silicon carbide layer is controlled to be 2050-10000sccm, further preferably 2200-10000sccm, and preferably 4000-10000sccm, so as to obtain a second hydrogen-doped silicon carbide layer having a target carbon doping concentration greater than that of the first hydrogen-doped silicon carbide layer and being suitable.

[0097] In some preferred embodiments of the present invention, the deposition conditions of the first hydrogen-doped silicon carbide layer and the second hydrogen-doped silicon carbide layer independently include: a deposition temperature of 350-600° C., and a deposition pressure of 1300-2500 mtorr.

[0098] In some preferred embodiments of the present invention, the deposition conditions of the first hydrogen-doped silicon carbide layer and the second hydrogen-doped silicon carbide layer independently include: the flow rate of silane is 800-2000sccm, and the flow rate of hydrogen is 2000-8000sccm. Using silane and hydrogen with appropriate flow rates to deposit the first hydrogen-doped silicon carbide layer and the second hydrogen-doped silicon carbide layer is more conducive to controlling the refractive index and passivation level of the film layer.

[0099] Preferably, in the present invention, the deposition power of the first hydrogen-doped silicon carbide layer is 3kw-15kw, and the deposition power of the second hydrogen-doped silicon carbide layer is 5kw-20kw. Using different deposition power ranges is more conducive to controlling the deposition rate and quality of the film layer.

[0100] In some preferred embodiments of the present invention, the hydrogen-doped and carbon-doped silicon layer, the first hydrogen-doped silicon carbide layer, and the second hydrogen-doped silicon carbide layer are all deposited using PECVD equipment (preferably tubular PECVD).

[0101] In some preferred embodiments of the present invention, the method for preparing a back contact battery capable of reducing LID further comprises:

[0102] A first semiconductor layer is formed on the back of the silicon wafer, and then a second semiconductor opening area is formed; then a texturing cleaning is performed to form a texturing surface on the light-receiving surface of the silicon wafer and the second semiconductor opening area; then a target film layer is deposited on the light-receiving surface of the silicon wafer, and then a second semiconductor layer is deposited on the back, and then a first semiconductor opening area arranged alternately with the second semiconductor opening area is formed on part of the second semiconductor layer;

[0103] A conductive film layer is deposited on the obtained back side, and an isolation groove is formed on a portion of the conductive film layer located between the first semiconductor opening area and the second semiconductor opening area; then metal electrodes are formed on the outer surfaces of the corresponding conductive film layers in the areas where the first semiconductor opening area and the second semiconductor opening area are located.

[0104] The texturing and cleaning in the present invention can remove the residual isolation layer and the first semiconductor layer in the second semiconductor opening area, and form a texturing surface on the light-receiving surface of the silicon wafer and the second semiconductor opening area.

[0105] Preferably, the method for preparing a back-contact cell capable of reducing LID further comprises: after depositing the anti-reflection layer, performing the steps of removing the back-surface coating and cleaning the second semiconductor opening area, and then depositing the second semiconductor layer. Further preferably, the solution and process used for removing the back-surface coating and cleaning the second semiconductor opening area can refer to the prior art, for example, the solution can be a hydrofluoric acid solution with a mass percentage of 1%-10%, and the process conditions used include, for example: a processing temperature of 20°C-30°C, and a removal time of 30-500s.

[0106] In a specific embodiment, the method for preparing a back contact battery capable of reducing LID specifically comprises the following steps:

[0107] S1, provide double-sided polished silicon wafers;

[0108] S2, forming a first semiconductor layer and an isolation layer in sequence on the back side of the silicon wafer;

[0109] S3, performing a first etching opening on the back surface obtained in S2 to form a second semiconductor opening region;

[0110] S4, forming a velvet surface on the light-receiving surface of the silicon wafer and the second semiconductor opening region by texturing and cleaning, and then selecting whether to perform a step of removing the isolation layer outside the second semiconductor opening region on the back side of the silicon wafer by cleaning according to needs;

[0111] S5, depositing a light-receiving surface passivation layer including a first tunneling oxide layer and a hydrogen-doped and carbon-doped silicon layer on the light-receiving surface of the silicon wafer in sequence, and then continuing to deposit an anti-reflection layer including a first hydrogen-doped silicon carbide layer and a second hydrogen-doped silicon carbide layer on the light-receiving surface;

[0112] S6, depositing a second semiconductor layer on the back side;

[0113] S7, performing a second etching opening on a portion of the second semiconductor layer on the back side of the silicon wafer to form a first semiconductor opening region spaced apart from the second semiconductor opening region.

[0114] Furthermore, the method for preparing the back contact battery capable of reducing LID further comprises the following steps:

[0115] S8, depositing a conductive film layer on the back surface obtained in S7;

[0116] S9, performing a third etching opening on a portion of the conductive film layer located between the first semiconductor opening region and the second semiconductor opening region to form an isolation groove;

[0117] S10, forming metal electrodes on the outer surfaces of the corresponding conductive film layers in the areas where the first semiconductor opening region and the second semiconductor opening region are located.

[0118] In a third aspect, the present invention provides a battery assembly, which includes the back contact battery capable of reducing LID as described in the first aspect.

[0119] The embodiments of the present invention are described in detail below, which are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0120] Example 1

[0121] A back contact battery, such as Figure 1 As shown, it is prepared by the following method:

[0122] S1, silicon wafer 1 (N-type single crystal silicon wafer) double-sided polishing:

[0123] S2, forming a first semiconductor layer and an isolation layer on the back side of the silicon wafer 1:

[0124] The first semiconductor layer includes a second tunneling silicon oxide layer 2 and an N-type doped polysilicon layer 3. The isolation layer is silicon nitride. The second tunneling silicon oxide layer 2 has a thickness of 1.5 nm, the N-type doped polysilicon layer 3 has a thickness of 120 nm, and an effective doping concentration of 2×10 20 cm -3 , the thickness of the isolation layer is 70nm.

[0125] S3, etching an opening on the back side of the silicon wafer 1 for the first time to form a second semiconductor opening region; the width W2 of the formed second semiconductor opening region is 530 μm.

[0126] S4, texturing and cleaning the light-receiving surface and the second semiconductor opening area on the back side of the silicon wafer 1;

[0127] During the texturing process of the light-receiving surface, the silicon nitride isolation layer on the back of the silicon wafer 1 is also removed by the final cleaning solution;

[0128] S5, forming a light-receiving surface passivation layer and an anti-reflection layer on the light-receiving surface of the silicon wafer 1:

[0129] The passivation layer is a first tunneling oxide layer 5 and a hydrogen-doped and carbon-doped silicon layer 6, the silicon layer is amorphous silicon, the thickness of the first tunneling oxide layer 5 is 1 nm, and the thickness of the hydrogen-doped and carbon-doped silicon layer 6 is 10 nm;

[0130] The hydrogen-doped and carbon-doped silicon layer 6 was deposited using a tubular PECVD device at a deposition temperature of 460°C, a silane flow rate of 1000sccm, a hydrogen flow rate of 18000sccm, a methane flow rate of 3000sccm, a deposition pressure of 2000mtorr, and a power of 3kw, and the deposition was performed to the target thickness. The flow ratio of silane, methane, and hydrogen was calculated to be 1:3:18. The refractive index of the hydrogen-doped and carbon-doped silicon layer 6 was controlled at 2.8, and the hydrogen concentration was 1.5×10 21 cm -3 , the carbon doping concentration is 3.6×10 18 cm -3 .

[0131] The anti-reflection layer 7 is a hydrogen-doped silicon carbide film layer, which includes a low-carbon-doped hydrogen-doped silicon carbide layer 7.1 (i.e., a first hydrogen-doped silicon carbide layer) and a high-carbon-doped hydrogen-doped silicon carbide layer 7.2 (i.e., a second hydrogen-doped silicon carbide layer); they are deposited using a tubular PECVD device at a deposition temperature of 460°C.

[0132] When depositing the low carbon-doped hydrogen-doped silicon carbide layer 7.1, the flow rate of silane is 900 sccm, the flow rate of methane is 1500 sccm, the flow rate of hydrogen is 5000 sccm, the deposition pressure is 1500 mtorr, and the power is 10 kW.

[0133] When depositing the highly carbon-doped hydrogen-doped silicon carbide layer 7.2, the flow rate of silane is 1200 sccm, the flow rate of methane is 9000 sccm, the flow rate of hydrogen is 7000 sccm, the deposition pressure is 2200 mtorr, and the power is 15 kW;

[0134] The total thickness of the anti-reflection layer 7 is 100 nm, wherein the thickness of the low carbon-doped hydrogen-doped silicon carbide layer 7.1 is 20 nm, the refractive index is 2.08, and the carbon doping concentration is 1.2×10 19 cm -3 , the hydrogen doping concentration is 5×10 21 cm -3 The thickness of the highly carbon-doped hydrogen-doped silicon carbide layer 7.2 is 80 nm, the refractive index is 1.96, and the carbon doping concentration is 7.5×10 19 cm -3 , the hydrogen doping concentration is 8×10 21 cm -3 .

[0135] Then, removing the back side coating layer and cleaning the second semiconductor opening area;

[0136] The removal of the back side coating and the cleaning of the second semiconductor opening area are carried out using HF acid solution, with a HF mass percentage of 2% and a deionized water mass percentage of 98%, a treatment temperature of 25° C., and a removal time of 100 s;

[0137] S6, forming a second semiconductor layer on the back side of the silicon wafer 1;

[0138] The second semiconductor layer is a stack of an intrinsic hydrogenated amorphous silicon layer 8 and a P-type doped amorphous silicon layer 9; the intrinsic hydrogenated amorphous silicon layer 8 has a thickness of 8 nm; the P-type doped amorphous silicon layer 9 has a thickness of 13 nm and an effective doping concentration of 6×10 19 cm -3 .

[0139] S7, etching an opening on the back side of the silicon wafer 1 for the second time to form a first semiconductor opening region; the width W1 of the formed first semiconductor opening region is 250 μm.

[0140] S8, depositing a conductive film layer 10 on the back side of the silicon wafer 1;

[0141] S9, etching an opening on the back side of the silicon wafer 1 for the third time to form an isolation groove; the width W3 of the isolation groove is 90 μm, and the resistance between the first semiconductor and the second semiconductor after etching is greater than 1 kΩ.

[0142] S10, forming metal electrodes 11 on the outer surfaces of the first semiconductor opening region and the second semiconductor opening region corresponding to the back side of the silicon wafer 1.

[0143] Example 2

[0144] The method of Example 1 is followed, except that the carbon doping concentration of the second hydrogen-doped silicon carbide layer is adjusted to 1.8×10 19 cm -3 , after calculation, the ratio of the carbon doping concentration of the first hydrogen-doped silicon carbide layer to the second hydrogen-doped silicon carbide layer is 1:1.5; accordingly, the refractive index of the second hydrogen-doped silicon carbide layer is 2.02. To meet this condition, the corresponding preparation process needs to be adjusted accordingly: the flow rate of methane is reduced to 2200sccm.

[0145] Example 3

[0146] The method of Example 1 is referred to, except that the thickness of the second hydrogen-doped silicon carbide layer is adjusted to 50 nm, and the thickness ratio of the first hydrogen-doped silicon carbide layer to the second hydrogen-doped silicon carbide layer is calculated to be 1:2.5. To meet this condition, corresponding adjustments need to be made: reducing the deposition time by 37.5%.

[0147] Example 4

[0148] The method of Example 1 is followed, except that the refractive index of the second hydrogen-doped silicon carbide layer is adjusted to be equal to the refractive index of the first hydrogen-doped silicon carbide layer. To meet this condition, corresponding adjustments are required: the flow rate of methane is reduced to 2050 sccm, and the carbon doping concentration of the obtained second hydrogen-doped silicon carbide layer is 1.98×10 19cm -3 , the hydrogen doping concentration is 5.5×10 21 cm -3 .

[0149] Example 5

[0150] The method of Example 1 is followed, except that the hydrogen concentration of the second hydrogen-doped silicon carbide layer is adjusted to 6.5×10 21 cm -3 To meet this condition, corresponding adjustments are required: the flow rate of hydrogen is reduced by 18.75%. After calculation, the ratio of hydrogen concentration between the first hydrogen-doped silicon carbide layer and the second hydrogen-doped silicon carbide layer is 1:1.3. Correspondingly, the refractive index of the second hydrogen-doped silicon carbide layer is 1.93.

[0151] Example 6

[0152] The method of Example 1 is followed, except that the hydrogen concentration in the hydrogen-doped and carbon-doped silicon layer is adjusted to 0.5×10 21 cm -3 , it is calculated that the ratio of the hydrogen concentration in the hydrogen-doped and carbon-doped silicon layer to the hydrogen concentration in the first hydrogen-doped silicon carbide film layer is 1: 10. Correspondingly, the refractive index of the hydrogen-doped and carbon-doped silicon layer is 3.1.

[0153] Example 7

[0154] The method of Example 1 is referred to, except that the thickness of the hydrogen-doped and carbon-doped silicon layer is adjusted to 15 nm. According to calculation, the thickness ratio of the hydrogen-doped silicon carbide film layer to the hydrogen-doped and carbon-doped silicon layer is 6.67:1.

[0155] Example 8

[0156] The method of Example 1 is referred to, except that the amorphous silicon layer in the hydrogen- and carbon-doped silicon layer is replaced with hydrogen- and carbon-doped polycrystalline silicon, and the hydrogen- and carbon-doping concentrations and thicknesses remain unchanged.

[0157] Example 9

[0158] The method of Example 1 is referred to, except that the structure of the first semiconductor layer is different, and the passivation structure is a heterojunction. Specifically, the first semiconductor layer is an intrinsic amorphous silicon layer and an N-type doped amorphous silicon layer. The thickness of the intrinsic amorphous silicon layer is 10 nm, the thickness of the N-type doped amorphous silicon layer is 60 nm, and the effective doping concentration is 1e19 cm -3 .

[0159] Comparative Example 1

[0160] The method of Example 1 is referred to, except that the light-receiving surface passivation layer and the anti-reflection layer are conventional film layers. Specifically, the light-receiving surface passivation layer is a first tunneling oxide layer (with the same thickness as in Example 1) and N-type doped amorphous silicon (i.e., not doped with carbon or hydrogen). The thickness of the N-type doped amorphous silicon is 10 nm, and the phosphorus doping concentration is 2×10 20 cm -3 ; The anti-reflection layer is silicon nitride with a thickness of 100nm.

[0161] Comparative Example 2

[0162] The method of Example 1 is followed, except that the hydrogen-doped and carbon-doped silicon layer in the light-receiving surface passivation layer is replaced by conventional N-type doped amorphous silicon (i.e., not doped with carbon or hydrogen), the thickness of the N-type doped amorphous silicon is 10 nm, and the phosphorus doping concentration is 2×10 20 cm -3 .

[0163] Comparative Example 3

[0164] The method of Example 1 is referred to, except that the anti-reflection layer is a conventional film layer, specifically silicon nitride with a thickness of 100 nm.

[0165] Comparative Example 4

[0166] The method of Example 1 is followed, except that the flow rate of methane and the deposition power of the first hydrogen-doped silicon carbide layer are increased so that the carbon doping concentration of the first hydrogen-doped silicon carbide layer in the anti-reflection layer is adjusted to be equal to the carbon doping concentration of the second hydrogen-doped silicon carbide layer. Accordingly, the refractive index of the first hydrogen-doped silicon carbide layer is 1.90.

[0167] Comparative Example 5

[0168] The method of Example 1 is referred to, except that the thickness of the first hydrogen-doped silicon carbide layer in the anti-reflection layer is adjusted to be equal to the thickness of the second hydrogen-doped silicon carbide layer.

[0169] Comparative Example 6

[0170] The method of Example 1 is followed, except that the hydrogen concentration in the hydrogen-doped and carbon-doped silicon layer is adjusted to 8.5×10 19 cm -3 , it is calculated that the ratio of the hydrogen concentration in the hydrogen-doped and carbon-doped silicon layer to the hydrogen concentration in the second hydrogen-doped silicon carbide film layer is 1:94. Correspondingly, the refractive index of the hydrogen-doped and carbon-doped silicon layer is 2.58.

[0171] Test Case

[0172] The back contact cells obtained in the above-mentioned embodiments and comparative examples were subjected to performance tests, and the results are shown in Table 1. Among them, the performance indicators of each embodiment and comparative example were converted using embodiment 1 as a reference benchmark, the data of embodiment 1 was normalized to 1.000, and other examples were converted based on embodiment 1, such as the LID pre- and post-attenuation ratio of comparative example 1 / the LID pre- and post-attenuation ratio of embodiment 1 was 307.500.

[0173] The test method for the attenuation ratio before and after LID is: use a halogen lamp, set the light intensity to 1000W / m², simulate the standard solar spectrum, and continuously illuminate for 96 hours to evaluate the power attenuation ratio of the cell before and after the cumulative irradiation to determine the light attenuation. The smaller the attenuation ratio before and after LID, the stronger the LID anti-attenuation ability and the higher the battery stability.

[0174] The test method for production yield is: in the production of a batch (100 batteries), the number of batteries that meet the standard of battery conversion efficiency above 26.5% and have no obvious color difference, broken corners, or scratches visible to the naked eye / the total number of batteries produced.

[0175] Table 1

[0176]

[0177] It can be seen from the above results that, compared with the comparative example, the embodiment of the present invention can take into account the passivation effect, optical effect and LID anti-attenuation ability, which is beneficial to reduce LID, improve battery stability and improve battery reliability.

[0178] Furthermore, according to Example 1 and Examples 2-9, it can be seen that the preferred solution of the present invention is more conducive to taking into account the passivation effect, optical effect and LID anti-attenuation ability.

[0179] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A back contact cell capable of reducing LID, comprising a silicon wafer, a light-receiving surface passivation layer and an anti-reflection layer sequentially arranged on the light-receiving surface of the silicon wafer, characterized in that: The light-receiving surface passivation layer comprises a first tunneling oxide layer and a hydrogen-doped and carbon-doped silicon layer which are sequentially arranged, and the silicon layer is amorphous silicon or polycrystalline silicon; the anti-reflection layer comprises a hydrogen-doped silicon carbide film layer, and the hydrogen-doped silicon carbide film layer comprises a first hydrogen-doped silicon carbide layer and a second hydrogen-doped silicon carbide layer which are sequentially arranged, the carbon doping concentration of the first hydrogen-doped silicon carbide layer is less than the carbon doping concentration of the second hydrogen-doped silicon carbide layer, the thickness of the first hydrogen-doped silicon carbide layer is 10-30 nm, the thickness of the second hydrogen-doped silicon carbide layer is 50-100 nm, and the ratio of the hydrogen doping concentration in the hydrogen-doped and carbon-doped silicon layer to the hydrogen doping concentration in the first hydrogen-doped silicon carbide layer is 1:(1-10), the ratio of the hydrogen doping concentration in the hydrogen-doped and carbon-doped silicon layer to the hydrogen doping concentration in the second hydrogen-doped silicon carbide layer is 1:(1-16), and the carbon doping concentration of the first hydrogen-doped silicon carbide layer is 1×10 18 cm -3 -9×10 19 cm -3 The carbon doping concentration of the second hydrogen-doped silicon carbide layer is 1×10 19 cm -3 -9×10 20 cm -3 The hydrogen concentration of the first hydrogen-doped silicon carbide layer is 1×10 21 cm -3 -6×10 22 cm -3 The hydrogen concentration of the second hydrogen-doped silicon carbide layer is 1×10 21 cm -3 -6×10 22 cm -3 The hydrogen concentration in the hydrogen-doped and carbon-doped silicon layer is 1×10 20 cm -3 -9×10 21 cm -3 The carbon doping concentration in the hydrogen-doped and carbon-doped silicon layer is 1×10 18 cm -3 -3.3×10 19 cm -3 .

2. The back contact battery capable of reducing LID according to claim 1, characterized in that: The ratio of the carbon doping concentration of the first hydrogen-doped silicon carbide layer to the second hydrogen-doped silicon carbide layer is 1:(0.5-650), and the unit of the carbon doping concentration is cm -3 .

3. The back contact battery capable of reducing LID according to claim 1, characterized in that: The total thickness of the anti-reflection layer is 70-130 nm; and / or the thickness ratio of the first hydrogen-doped silicon carbide layer to the second hydrogen-doped silicon carbide layer is 1:(1.7-10).

4. The back contact battery capable of reducing LID according to claim 1, characterized in that: The refractive index of the first hydrogen-doped silicon carbide layer is 2.0-2.2, and the refractive index of the second hydrogen-doped silicon carbide layer is 1.93-2.

08.

5. The back contact battery capable of reducing LID according to claim 1, characterized in that: The refractive index of the first hydrogen-doped silicon carbide layer is greater than the refractive index of the second hydrogen-doped silicon carbide layer.

6. The back contact battery capable of reducing LID according to claim 1, characterized in that: The ratio of hydrogen doping concentrations of the first hydrogen doped silicon carbide layer and the second hydrogen doped silicon carbide layer is 1:(0.1-60).

7. The back contact battery capable of reducing LID according to claim 1, characterized in that: The thickness of the hydrogen-doped and carbon-doped silicon layer is 6-18 nm.

8. The back contact battery capable of reducing LID according to claim 1, characterized in that: The thickness ratio of the hydrogen-doped silicon carbide film layer to the hydrogen-doped and carbon-doped silicon layer is (4.5-20):

1.

9. The back contact battery capable of reducing LID according to claim 1, characterized in that: The hydrogen-doped and carbon-doped silicon layer is hydrogen-doped and carbon-doped amorphous silicon; and / or the refractive index of the hydrogen-doped and carbon-doped silicon layer is 2.0-3.

1.

10. The back contact battery capable of reducing LID according to claim 1, characterized in that: The back-contact battery capable of reducing LID also includes a first semiconductor layer and a second semiconductor layer alternately arranged on the back side of a silicon wafer, the first semiconductor layer includes a first passivation layer and a first doped silicon layer, the second semiconductor layer includes a second passivation layer and a second doped silicon layer, the first passivation layer and the second passivation layer are each independently a second tunneling oxide layer or an intrinsic silicon layer, and the first doped silicon layer and the second doped silicon layer are each independently doped polycrystalline silicon, doped amorphous silicon or doped microcrystalline silicon.

11. The back contact battery capable of reducing LID according to claim 10, characterized in that: The back contact cell capable of reducing LID further comprises at least one of the following structures: Structure 1: The first passivation layer is the second tunneling oxide layer, the first doped silicon layer is doped polycrystalline silicon, the second passivation layer is an intrinsic silicon layer, and the second doped silicon layer is doped amorphous silicon or doped microcrystalline silicon; the first doped silicon layer is thickened to 80-150nm, and the second doped silicon layer is thickened to 5-15nm; Structure 2: Both ends of the second semiconductor layer extend outward to cover the back side of the adjacent first semiconductor layer, and a first semiconductor opening region not covering the second semiconductor layer is provided on the back side of the first semiconductor layer, a second semiconductor opening region is formed between adjacent first semiconductor layers, the second semiconductor opening region is arranged at intervals from the first semiconductor opening region, and the region between them is a spacing region; in the spacing region, an isolation layer is provided between the first semiconductor layer and the second semiconductor layer, or no isolation layer is provided; the back contact battery capable of reducing LID further comprises a metal electrode and a conductive film layer laid on the outer surfaces of the first semiconductor layer and the second semiconductor layer, an isolation groove is provided on the portion of the conductive film layer located in the spacing region; the metal electrode is provided on the outer surfaces of the conductive film layers corresponding to the second semiconductor opening region and the first semiconductor opening region; Structure 3: The second semiconductor layer attachment area on the back of the silicon wafer and the light-receiving surface of the silicon wafer are respectively the textured surfaces, and the first semiconductor layer attachment area on the back of the silicon wafer is the polished surface; Structure 4: The thickness of the first tunneling oxide layer is 1-2 nm.

12. A method for preparing a back contact battery capable of reducing LID, characterized in that: The method is used for preparing a back contact battery capable of reducing LID as claimed in any one of claims 1 to 11, and the preparation method comprises the following steps: Depositing a light-receiving surface passivation layer including a first tunneling oxide layer and a hydrogen-doped and carbon-doped silicon layer on the light-receiving surface of the silicon wafer in sequence, and then depositing an anti-reflection layer including a first hydrogen-doped silicon carbide layer and a second hydrogen-doped silicon carbide layer on the light-receiving surface; Wherein, when the hydrogen-doped and carbon-doped silicon layer is deposited, the flow rate ratio of silane, methane and hydrogen is controlled to be 1: (0.5-9): (3-20); When the first hydrogen-doped silicon carbide layer is deposited, the flow rate of the introduced methane is controlled to be 480-2000 sccm, and when the second hydrogen-doped silicon carbide layer is deposited, the flow rate of the introduced methane is controlled to be 2050-10000 sccm.

13. The method for preparing a back contact battery capable of reducing LID according to claim 12, characterized in that: The flow rate of silane during the deposition of the hydrogen-doped and carbon-doped silicon layer is 800-2000 sccm; and / or, The deposition conditions of the hydrogen-doped and carbon-doped silicon layer include: a deposition temperature of 350-600° C., a hydrogen flow rate of 2000-30000 sccm, a methane flow rate of 800-15000 sccm, a deposition pressure of 1300-3000 mtorr, and a power of 2 kW-10 kW.

14. The method for preparing a back contact battery capable of reducing LID according to claim 12 or 13, characterized in that: The deposition conditions of the first hydrogen-doped silicon carbide layer and the second hydrogen-doped silicon carbide layer independently include: a deposition temperature of 350-600°C, a silane flow rate of 800-2000sccm, a hydrogen flow rate of 2000-8000sccm, and a deposition pressure of 1300-2500mtorr; and a deposition power of 3kw-15kw for the first hydrogen-doped silicon carbide layer and a deposition power of 5kw-20kw for the second hydrogen-doped silicon carbide layer.

15. The method for preparing a back contact battery capable of reducing LID according to claim 12, characterized in that: The hydrogen-doped and carbon-doped silicon layer, the first hydrogen-doped silicon carbide layer, and the second hydrogen-doped silicon carbide layer are all deposited using a tubular PECVD device; and / or, The method for preparing the back contact battery capable of reducing LID also includes: A first semiconductor layer is formed on the back of the silicon wafer, and then a second semiconductor opening area is formed; then a texturing cleaning is performed to form a texturing surface on the light-receiving surface of the silicon wafer and the second semiconductor opening area; then a target film layer is deposited on the light-receiving surface of the silicon wafer, and then a second semiconductor layer is deposited on the back, and then a first semiconductor opening area arranged alternately with the second semiconductor opening area is formed on part of the second semiconductor layer; A conductive film layer is deposited on the obtained back side, and an isolation groove is formed on a portion of the conductive film layer located between the first semiconductor opening area and the second semiconductor opening area; then metal electrodes are formed on the outer surfaces of the corresponding conductive film layers in the areas where the first semiconductor opening area and the second semiconductor opening area are located.

16. A battery assembly, characterized in that: It comprises a back contact cell capable of reducing LID as claimed in any one of claims 1 to 11.

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