Heterojunction solar cell and preparation method thereof

Abstract

The invention relates to the technical field of solar energy, in particular to a heterojunction solar cell and a preparation method thereof. The preparation method of the heterojunction solar cell comprises the following steps: providing a substrate which comprises a first surface and a second surface which are oppositely arranged; respectively forming at least one first intrinsic passivation layer and at least one second intrinsic passivation layer on the first surface and the second surface of the substrate; forming at least one first transition layer on the first intrinsic passivation layer, wherein the first transition layer is made of an n-type amorphous silicon-based material; forming at least one n-type doped layer on the first transition layer; forming at least one p-type doped layer on the second intrinsic passivation layer; respectively forming at least one first transparent conductive layer and at least one second transparent conductive layer on the n-type doped layer and the p-type doped layer; and respectively forming a first electrode and a second electrode on the first transparent conductive layer and the second transparent conductive layer. By arranging the first transition layer between the n-type doping layer and the substrate, effective doping of the n-type doping layer is increased.

Description

Technical Field

[0001] The present disclosure relates to the field of solar energy technology, and in particular to a heterojunction solar cell and a preparation method thereof. Background Art

[0002] Heterojunction solar cells have attracted extensive attention due to their high opening voltage and high conversion efficiency. However, the carrier transmission barrier caused by the undesirable passivation contact limits the further improvement of efficiency, especially the contact efficiency between the doped layer and the transparent conductive layer (TCO). Conventional double-sided microcrystalline heterojunction cells have doped microcrystalline silicon in direct contact with TCO. Compared with amorphous silicon, microcrystalline silicon has a lower hydrogen content, which reduces the passivation effect of hydrogen during the TCO coating growth process. In addition, the high-efficiency transmission of carriers is limited by factors such as lattice mismatch between the P-type microcrystalline silicon and the N-type TCO on the back.

[0003] Currently, large-scale mass-produced heterojunction cells are usually double-sided microcrystalline structures, with the front film layer being intrinsic amorphous silicon / N-type doped microcrystalline silicon / TCO, and the back film layer being intrinsic amorphous silicon / P-type doped microcrystalline silicon / TCO. The doped microcrystalline silicon film layer itself has a low hydrogen content and cannot provide sufficient hydrogen to passivate defects during the subsequent TCO coating growth process, thus reducing the conductivity of the TCO and limiting the efficiency of the cell.

[0004] In addition, the main component of TCO is indium oxide, whose lattice constant and interplanar spacing are quite different from those of microcrystalline silicon, while both microcrystalline silicon and TCO film layers have good crystallinity and crystal structure. Therefore, there is a large amount of lattice mismatch between the two materials in the contact interface area, which leads to the generation of interface states and affects the transmission and collection of carriers.

[0005] Therefore, the contact problem between doped microcrystalline silicon and TCO in heterojunction solar cells needs to be improved urgently. Summary of the invention

[0006] Based on this, it is necessary to provide a heterojunction solar cell and a method for preparing the same in order to improve the carrier transfer efficiency in the prior art.

[0007] In order to achieve the above object, on the one hand, a method for preparing a heterojunction solar cell is provided, comprising:

[0008] Providing a substrate, the substrate comprising a first surface and a second surface disposed opposite to each other;

[0009] forming at least one first intrinsic passivation layer and at least one second intrinsic passivation layer on the first surface and the second surface of the substrate respectively;

[0010] forming at least one first transition layer on the first intrinsic passivation layer, wherein the material of the first transition layer is an n-type amorphous silicon-based material;

[0011] forming at least one n-type doped layer on the first transition layer;

[0012] forming at least one p-type doped layer on the second intrinsic passivation layer;

[0013] forming at least one first transparent conductive layer and at least one second transparent conductive layer on the n-type doping layer and the p-type doping layer, respectively;

[0014] A first electrode and a second electrode are formed on the first transparent conductive layer and the second transparent conductive layer, respectively.

[0015] In one embodiment, before forming at least one first transparent conductive layer and at least one second transparent conductive layer on the n-type doped layer and the p-type doped layer respectively, the method comprises:

[0016] At least one second transition layer is formed on the n-type doped layer, wherein the material of the second transition layer is an n-type amorphous silicon-based material.

[0017] In one embodiment, before forming at least one first transparent conductive layer and at least one second transparent conductive layer on the n-type doped layer and the p-type doped layer respectively, the method comprises:

[0018] At least one third transition layer is formed on the p-type doped layer, and the material of the third transition layer is an n-type microcrystalline silicon-based material.

[0019] In one of the embodiments, the material of the third transition layer is n-type oxygen-doped microcrystalline silicon-based material.

[0020] In one embodiment, before forming at least one first transparent conductive layer and at least one second transparent conductive layer on the n-type doped layer and the p-type doped layer respectively, the method comprises:

[0021] At least one fourth transition layer is formed on the third transition layer, and the material of the fourth transition layer is an n-type amorphous silicon-based material.

[0022] In one of the embodiments, the material of the n-type doping layer and the p-type doping layer is a microcrystalline silicon-based material.

[0023] In another aspect, a heterojunction solar cell is provided, comprising:

[0024] A substrate having a first surface and a second surface disposed opposite to each other;

[0025] at least one first intrinsic passivation layer disposed on the first surface of the substrate;

[0026] At least one first transition layer, located on a side of the first intrinsic passivation layer away from the substrate, wherein the material of the first transition layer is an n-type amorphous silicon-based material;

[0027] at least one n-type doped layer, located on the first transition layer;

[0028] at least one first transparent conductive layer, located on the n-type doped layer;

[0029] at least one first electrode, located on the first transparent conductive layer;

[0030] at least one second intrinsic passivation layer disposed on the second surface of the substrate;

[0031] at least one p-type doped layer, located on a side of the second intrinsic passivation layer away from the substrate;

[0032] at least one second transparent conductive layer, located on the p-type doped layer;

[0033] At least one second electrode is located on the second transparent conductive layer.

[0034] In one of the embodiments, the heterojunction solar cell further includes: at least one second transition layer located between the n-type doped layer and the first transparent conductive layer, and the material of the second transition layer is an n-type amorphous silicon-based material.

[0035] In one embodiment, the thickness of the first transition layer is 2 nm to 7 nm, and / or the thickness of the second transition layer is 2 nm to 7 nm.

[0036] In one of the embodiments, the heterojunction solar cell further includes: at least one third transition layer located between the p-type doped layer and the second transparent conductive layer, and the material of the third transition layer is an n-type microcrystalline silicon-based material.

[0037] In one of the embodiments, the material of the third transition layer is n-type oxygen-doped microcrystalline silicon-based material.

[0038] In one of the embodiments, the heterojunction solar cell further includes: at least one fourth transition layer located between the third transition layer and the second transparent conductive layer, and the material of the fourth transition layer is an n-type amorphous silicon-based material.

[0039] In one embodiment, the thickness of the third transition layer is 3 nm to 7 nm, and / or the thickness of the fourth transition layer is 2 nm to 7 nm.

[0040] In one of the embodiments, the material of the n-type doping layer and the p-type doping layer is a microcrystalline silicon-based material.

[0041] The heterojunction solar cell and its preparation method provided by the present application have the following beneficial effects: by setting a first transition layer between the n-type doping layer and the substrate to compensate for the problem of insufficient effective doping of the amorphous incubation layer of the n-type doping layer, the effective doping of the n-type doping layer is increased, and then the growth quality of the n-type doping layer can be increased, and the field passivation effect of the heterojunction solar cell is improved. Preferably, in the heterojunction solar cell provided by the present application, the front side can sequentially include the first intrinsic passivation layer-the first transition layer-the n-type doping layer-the second transition layer-the first transparent conductive layer, and the back side can sequentially include the second intrinsic passivation layer-the p-type doping layer-the third transition layer-the fourth transition layer-the second transparent conductive layer, wherein the materials of the n-type doping layer and the p-type doping layer are microcrystalline silicon-based materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present disclosure or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0043] Figure 1 is a schematic diagram of a heterojunction solar cell provided in one embodiment;

[0044] Figure 2 is a schematic diagram of a first microcrystalline layer provided in an embodiment;

[0045] Figure 3 is a schematic diagram of an n-type doping layer provided in an embodiment;

[0046] Figure 4 is a schematic diagram of an n-type doping layer provided in another embodiment;

[0047] Figure 5 is a flow chart of preparing a heterojunction solar cell provided in one embodiment;

[0048] Figures 6 to 15 Schematic diagram of an intermediate structure obtained during the preparation process of a heterojunction solar cell provided in different embodiments;

[0049] Fig.16 FIG. 4 is a schematic diagram of a heterojunction solar cell provided in another embodiment.

[0050] Explanation of the reference numerals: heterojunction solar cell-10; substrate-11; first intrinsic passivation layer-134; first transition layer-131; n-type doped layer-13; second transition layer-132; first transparent conductive layer-133; first electrode-125; second intrinsic passivation layer-124; p-type doped layer-12; third transition layer-121; fourth transition layer-122; second transparent conductive layer-123; second electrode-135.

[0051] In order to better describe and illustrate the embodiments and / or examples of the inventions disclosed herein, reference may be made to one or more drawings. The additional details or examples used to describe the drawings should not be considered as limiting the scope of any of the disclosed inventions, the embodiments and / or examples currently described, and the best modes of these inventions currently understood. DETAILED DESCRIPTION

[0052] In order to facilitate understanding of the present disclosure, the present disclosure will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present disclosure are shown in the drawings. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present disclosure more thorough and comprehensive.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present disclosure belongs. The terms used herein in the specification of the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure.

[0054] In each embodiment, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in each embodiment can be understood according to the specific situation.

[0055] It should be understood that when an element or layer is referred to as "on ...", "adjacent to ...", "connected to" other elements or layers, it can be directly on, adjacent to, connected to other elements or layers, or there can be intervening elements or layers. On the contrary, when an element is referred to as "directly on ...", "directly adjacent to ...", "directly connected to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers, doping types and / or parts, these elements, components, regions, layers, doping types and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, doping type or part from another element, component, region, layer, doping type or part. Therefore, without departing from the teaching of the present embodiment, the first element, component, region, layer, doping type or part discussed below can be represented as a second element, component, region, layer, doping type or part.

[0056] Spatially relative terms such as "under," "beneath," "below," "under," "above," "above," and the like may be used herein to describe the relationship of an element or feature shown in the figures to other elements or features. It should be understood that, in addition to the orientations shown in the figures, spatially relative terms also include different orientations of the device in use and operation. For example, if the device in the accompanying drawings is flipped, an element or feature described as "under other elements" or "under it" or "under it" will be oriented as being "above" the other elements or features. Thus, the exemplary terms "under" and "under" may include both upper and lower orientations. In addition, the device may also include additional orientations (e.g., rotated 90 degrees or other orientations), and the spatial descriptors used herein are interpreted accordingly.

[0057] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that when the terms "consisting of" and / or "comprising" are used in this specification, the presence of the features, integers, steps, operations, elements and / or parts can be determined, but the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups is not excluded. At the same time, when used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0058] Embodiments of the embodiments are described herein with reference to schematic diagrams that are ideal embodiments (and intermediate structures) of the present specification, and variations in the shapes shown due to, for example, manufacturing techniques and / or tolerances are anticipated. Thus, embodiments of the present embodiments should not be limited to the specific shapes of the regions shown herein, but include deviations in shapes due to, for example, manufacturing techniques. The regions shown in the figures are schematic in nature, and their shapes do not represent the actual shapes of the regions of the device and do not limit the scope of the present embodiments.

[0059] The heterojunction solar cell 10 provided in this application is as follows Figure 1 and Fig.16 As shown, Figures 2 to 4 1 are different embodiments of the heterojunction solar cell 10. Figure 5 In one embodiment, a method for preparing a heterojunction solar cell 10 is provided. Figures 6 to 15 Schematic diagram of an intermediate structure obtained during the preparation process of a heterojunction solar cell 10. The preparation method of the heterojunction solar cell 10 mainly includes the following steps:

[0060] Step S100: providing a substrate 11, wherein the substrate 11 comprises a first surface and a second surface which are opposite to each other.

[0061] Step S200 : forming at least one first intrinsic passivation layer 134 and at least one second intrinsic passivation layer 124 on the first surface and the second surface of the substrate 11 , respectively.

[0062] Step S300 : forming at least one first transition layer 131 on the first intrinsic passivation layer 134 . The material of the first transition layer 131 is an n-type amorphous silicon-based material.

[0063] Step S400 : forming at least one n-type doped layer 13 on the first transition layer 131 .

[0064] Step S500 : forming at least one p-type doping layer 12 on the second intrinsic passivation layer 124 .

[0065] Step S900 : forming at least one second transparent conductive layer 123 and at least one second transparent conductive layer 123 on the n-type doping layer and the p-type doping layer, respectively.

[0066] Step S1000 : forming a first electrode 125 and a second electrode 135 on the second transparent conductive layer 123 and the second transparent conductive layer 123 respectively.

[0067] In step S100, refer to Figure 6 The substrate 11 may include single crystal silicon. The first surface of the substrate 11 may be a light incident surface, and the second surface of the substrate 11 may be a backlight surface.

[0068] In step S200, refer to Figure 7 As an example, a chemical vapor deposition method can be used to form an intrinsic passivation layer on the first surface and the second surface of the substrate 11. The intrinsic passivation layer may include a first intrinsic passivation layer 134 and a second intrinsic passivation layer 124. The intrinsic passivation layer can improve the interface characteristics of the substrate 11, improve the performance and stability of the heterojunction solar cell 10, significantly reduce the interface recombination rate of the heterojunction solar cell 10, and improve the conversion efficiency of the heterojunction solar cell 10.

[0069] In step S300, refer to Figure 8 The first transition layer 131 can be formed by VHF or RF-PECVD. The material of the first transition layer 131 is an n-type amorphous silicon-based material. As an example, the thickness of the first transition layer 131 can be 2nm to 7nm.

[0070] In step S400, refer to Fig. 9 As an example, the n-type doping layer 13 may be an n-type microcrystalline silicon material, the film thickness of the n-type doping layer 13 may be between 8 nm and 14 nm, and the refractive index of the n-type doping layer 13 may be between 2.40 and 3.00. The above data are only examples, and in actual embodiments, the n-type doping layer 13 is not limited to the above data.

[0071] In step S500, refer to Fig.11 As an example, the p-type doping layer 12 may be made of p-type microcrystalline silicon material, the film thickness of the p-type doping layer 12 may be in the range of 18 nm to 24 nm, and the refractive index of the p-type doping layer 12 may be between 3.20 and 3.60.

[0072] Furthermore, both the n-type doping layer 13 and the p-type doping layer 12 can be made of microcrystalline silicon-based materials.

[0073] In step S900, refer to Fig.14 As an example, the material of the second transparent conductive layer 123 may include transparent conductive oxide, etc. For example, the material of the second transparent conductive layer 123 may include indium oxide, etc. Further, the material of the second transparent conductive layer 123 may be consistent with the material of the first transparent conductive layer 133 .

[0074] In step S1000, refer to Fig.15This embodiment does not limit the material, shape, etc. of the first electrode 125 and the second electrode 135. It can be understood that the first electrode 125 and the second electrode 135 may include a plurality of electrode units, and the plurality of electrode units are spaced and symmetrically arranged on the opposite surfaces of the first transparent conductive layer 133 and the second transparent conductive layer 123.

[0075] In the related art, oxygen can also be doped into the n-type doping layer 13. The oxygen-doped n-type doping layer can increase the band gap of the n-type doping layer, so that more high-energy photons can enter the n-type doping layer, increasing the light transmittance of the n-type doping layer. However, the inventors have found that in the early stage of the growth of the n-type doping layer, the n-type doping layer has a thick amorphous incubation layer, which will cause the crystallization rate of the n-type doping layer to be low.

[0076] In this embodiment, a first transition layer 131 can be set between the growing n-type doping layer 13 and the substrate 11 to compensate for the problem of insufficient effective doping of the amorphous incubation layer of the n-type doping layer 13, thereby increasing the effective doping of the n-type doping layer 13, and further increasing the growth quality of the n-type doping layer 13, thereby improving the field passivation effect of the heterojunction solar cell 10.

[0077] In one embodiment, see Fig.10 , between step S400 and step S900 may include:

[0078] Step S600 : forming at least one second transition layer 132 on the n-type doping layer 13 , wherein the material of the second transition layer 132 is an n-type amorphous silicon-based material.

[0079] The first transition layer 131 and the second transition layer 132 can be formed by VHF or RF-PECVD method. The thickness of the first transition layer 131 and the second transition layer 132 can be between 2nm and 7nm, and the refractive index of the first transition layer 131 and the second transition layer 132 can be between 3.90 and 4.20.

[0080] Specifically, in the process of forming the first transition layer 131 and the second transition layer 132, the reaction gas may be silane, and the doping gas may be phosphine or other P-doped gases. The ratio of phosphine to silane is 4 to 8 times. The above data are only used as examples. In actual embodiments, the parameters of the first transition layer 131 and the second transition layer 132 are not limited to the above data.

[0081] In this embodiment, firstly, the hydrogen content in the second transition layer 132 is greater than the hydrogen content in the n-type doped layer 13, which enables the second transition layer 132 to better contact with the first transparent conductive layer 133. It can be understood that when preparing the second transition layer 132 and the first transparent conductive layer 133, the hydrogen in the second transition layer 132 can provide sufficient hydrogen during the growth process of the first transparent conductive layer 133 to passivate the defects of the first transparent conductive layer 133, thereby improving the conductivity of the first transparent conductive layer 133 and improving the efficiency of the heterojunction solar cell 10. Secondly, the lattice constant and the interplanar spacing of the first transparent conductive layer 133 are greatly different from those of the n-type doped layer 13. In this embodiment, by setting the second transition layer 132 in the first transparent conductive layer 133 and the n-type doped layer 13, the second transition layer 132 relieves the lattice mismatch between the first transparent conductive layer 133 and the n-type doped layer 13, relieves the stress between the first transparent conductive layer 133 and the n-type doped layer 13, avoids the defects and transmission barriers caused by the lattice mismatch between the first transparent conductive layer 133 and the n-type doped layer 13, improves the transmission and passivation contact of carriers, reduces the generation of interface states, and improves the transmission and collection of carriers. In addition, in this embodiment, the second transition layer 132 also has a photoelectric conversion function, which can reduce the demand for the thickness of the n-type doped layer 13, reduce the coating time of the n-type doped layer 13, help to improve the production capacity of large-scale mass production of heterojunction batteries, and reduce equipment costs. Afterwards, in this embodiment, the first transition layer 131, the n-type doped layer 13, and the second transition layer 132 all have the first doping type, which makes the potential barrier between the multiple film layers on this side smaller, which is conducive to the improvement of photoelectric conversion efficiency. Furthermore, in this embodiment, the n-type doped layer 13 is provided to connect the second transition layer 132 , which can alleviate the disadvantage of insufficient lateral transmission of the n-type doped layer 13 , improve the contact between the entire N layer and the first transparent conductive layer 133 , and improve the series resistance of the heterojunction solar cell 10 .

[0082] In one embodiment, see Fig.12 , between step S500 and step S900 may include:

[0083] Step S700 : forming at least one third transition layer 121 on the p-type doped layer 12 , wherein the material of the third transition layer 121 is an n-type microcrystalline silicon-based material.

[0084] The third transition layer 121 can be deposited on the surface of the p-type doped layer 12 by RF-PECVD or VHF method. The thickness of the third transition layer 121 can be between 3nm and 7nm, and the refractive index of the third transition layer 121 can be between 3.20 and 3.60. The above data are only used as examples. In actual embodiments, the parameters of the p-type doped layer 12 and the third transition layer 121 are not limited to the above data.

[0085] Furthermore, the material of the third transition layer 121 may include an n-type oxygen-doped microcrystalline silicon-based material.

[0086] In this embodiment, firstly, the p-type doping layer 12 and the third transition layer 121 that are in contact with each other are provided with different doping types, respectively. At this time, the third transition layer 121 can improve the tunneling contact of the carrier collection of the p-type doping layer 12, reduce the barrier of the carrier transmission of the p-type doping layer 12, thereby effectively improving the conversion efficiency of the heterojunction solar cell 10. For example, when the p-type doping layer 12 is a P-type microcrystalline layer, the third transition layer 121 can improve the tunneling contact of the hole collection of the P-type microcrystalline layer. Secondly, in this embodiment, the p-type doping layer 12 and the third transition layer 121 are both microcrystalline layers. At this time, compared with the amorphous layer in the conventional technology, the p-type doping layer 12 and the third transition layer 121 have better photoelectric conversion efficiency, and the stability of the heterojunction solar cell 10 is better. Afterwards, the p-type doping layer 12 has a second doping type different from the first doping type, and the third transition layer 121 has a first doping type, so that the potential barriers inside the three film layers can be reduced. Furthermore, in this embodiment, a third transition layer 121 is set on the p-type doped layer 12, and a higher tunneling efficiency can be obtained by adjusting the thickness and doping process of the microcrystalline NP layer (p-type doped layer 12 and the third transition layer 121), thereby improving the series resistance of the heterojunction solar cell 10.

[0087] In one embodiment, see Fig.13 , between step S500 and step S900 may include:

[0088] Step S800 : forming at least one fourth transition layer 122 on the third transition layer 121 , wherein the material of the fourth transition layer 122 is an n-type amorphous silicon-based material.

[0089] After forming the p-type doped layer 12, a third transition layer 121 and a fourth transition layer 122 may be formed continuously. The fourth transition layer 122 may also be formed by VHF or RF-PECVD. The film thickness of the fourth transition layer 122 may be between 2 nm and 7 nm, and the refractive index of the fourth transition layer 122 may be between 3.90 and 4.20.

[0090] The reaction gas for forming the fourth transition layer 122 may be silane, and the doping gas of the fourth transition layer 122 may be phosphine or other P-doped gas. The ratio of phosphine to silane is 5 to 10 times. The above data are only used as examples. In actual embodiments, the parameters of the fourth transition layer 122 are not limited to the above data.

[0091] In this embodiment, the hydrogen content in the fourth transition layer 122 is greater than the hydrogen content in the p-type doped layer 12, which allows the fourth transition layer 122 to better contact the second transparent conductive layer 123 and improve the growth of the second transparent conductive layer 123. It can be understood that when preparing the fourth transition layer 122 and the second transparent conductive layer 123, the hydrogen in the fourth transition layer 122 can provide sufficient hydrogen during the growth of the second transparent conductive layer 123 to passivate the defects of the second transparent conductive layer 123, thereby improving the conductivity of the second transparent conductive layer 123 and improving the efficiency of the heterojunction solar cell 10. Again, the lattice constant and interplanar spacing of the second transparent conductive layer 123 are greatly different from those of the p-type doped layer 12. In this embodiment, by setting the fourth transition layer 122 in the second transparent conductive layer 123 and the p-type doped layer 12, the fourth transition layer 122 relieves the lattice mismatch between the second transparent conductive layer 123 and the p-type doped layer 12, relieves the stress between the second transparent conductive layer 123 and the p-type doped layer 12, avoids the defects and transmission barriers caused by the lattice mismatch between the second transparent conductive layer 123 and the p-type doped layer 12, improves the transmission and passivation contact of carriers, reduces the generation of interface states, and also improves the transmission and collection of carriers. Therefore, in this embodiment, the fourth transition layer 122 also has a photoelectric conversion function, which can reduce the demand for the thickness of the p-type doped layer 12, reduce the coating time of the p-type doped layer 12, help to improve the production capacity of large-scale mass production of heterojunction batteries, and reduce equipment costs.

[0092] It should be understood that although Figure 5 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 5 At least part of the steps may include multiple steps or multiple stages. These steps or stages are not necessarily performed at the same time, but can be performed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed in turn or alternately with other steps or at least part of the steps or stages in other steps.

[0093] Based on the same inventive concept, please refer to Figure 1 and Fig.16 This embodiment provides a heterojunction solar cell 10, which mainly includes a substrate 11, a first intrinsic passivation layer 134, a first transition layer 131, an n-type doped layer 13, a first transparent conductive layer 133 and a first electrode 125 on the front side, and a second intrinsic passivation layer 124, a p-type doped layer 12, a second transparent conductive layer 123 and a second electrode 135 on the back side; or,

[0094] The first intrinsic passivation layer 134, the first transition layer 131, the n-type doped layer 13, the second transition layer 132, the first transparent conductive layer 133 and the first electrode 125 are located on the front side, and the second intrinsic passivation layer 124, the p-type doped layer 12, the third transition layer 121, the fourth transition layer 122, the second transparent conductive layer 123 and the second electrode 135 are located on the back side.

[0095] The material of the substrate 11 may include silicon, germanium, or germanium silicon. For example, the material of the substrate 11 may include single crystal silicon. This embodiment does not specifically limit the thickness, shape, and material of the substrate 11. The substrate 11 may include a first surface and a second surface that are arranged opposite to each other. As an example, the first surface may be a light incident surface, and the second surface may be a backlight surface.

[0096] The heterojunction solar cell 10 may further include a first intrinsic passivation layer 134 and a second intrinsic passivation layer 124, wherein the first intrinsic passivation layer 134 and the second intrinsic passivation layer 124 are respectively located on the front and back of the substrate 11. The intrinsic passivation layer can improve the interface characteristics of the substrate 11, improve the performance and stability of the heterojunction solar cell 10, significantly reduce the interface recombination rate of the heterojunction solar cell 10, and improve the conversion efficiency of the heterojunction solar cell 10.

[0097] The first transition layer 131 may be located on the first surface of the substrate 11 and between the first intrinsic passivation layer 134 and the n-type doping layer 13. The first transition layer 131 may have a first doping type. As an example, the first doping type may be an N-type doping. In this case, the first transition layer 131 may be an N-type amorphous buffer layer. Further, the thickness of the first transition layer 131 is 2 nm to 7 nm.

[0098] See also Figure 3 and Figure 4 The n-type doping layer 13 may be located on the side of the first transition layer 131 away from the substrate 11, and the n-type doping layer 13 has a first doping type. As an example, the first doping type may be n-type doping. In this case, the n-type doping layer 13 may be an n-type microcrystalline layer.

[0099] Oxygen can also be doped into the n-type doping layer 13. The oxygen-doped n-type doping layer 13 can increase the band gap of the n-type doping layer 13, so that more high-energy photons can enter the n-type doping layer 13, increasing the light transmittance of the n-type doping layer 13. However, the inventors have found that in the early stage of the growth of the n-type doping layer 13, the n-type doping layer 13 has a thick amorphous incubation layer, which will cause the crystallization rate of the n-type doping layer 13 to be low.

[0100] The p-type doping layer 12 has a second doping type. As an example, the second doping type may be a P-type doping. In this case, the p-type doping layer 12 may be a P-type microcrystalline layer. In the heterojunction solar cell 10, the p-type doping layer 12 may be a functional layer.

[0101] The material of the second transparent conductive layer 123 may include transparent conductive oxide, etc. For example, the material of the second transparent conductive layer 123 may include indium oxide, etc. As an example, the material of the second transparent conductive layer 123 may be consistent with the material of the first transparent conductive layer 133 .

[0102] The heterojunction solar cell 10 may further include a first electrode 125 and a second electrode 135 . The first electrode 125 and the second electrode 135 may include a plurality of electrode units. The plurality of electrode units are spaced and symmetrically arranged on the second transparent conductive layer 123 and on the surface opposite to the second transparent conductive layer 123 .

[0103] In this embodiment, a first transition layer 131 may be provided between the growing n-type doping layer 13 and the substrate to compensate for the problem of insufficient doping of the amorphous incubation layer of the n-type doping layer 13 , thereby increasing the effective doping of the n-type doping layer 13 and further improving the growth quality of the n-type doping layer 13 .

[0104] In one embodiment, the heterojunction solar cell 10 further includes: at least one second transition layer 132 located between the n-type doped layer 13 and the first transparent conductive layer 133 , and the material of the second transition layer 132 is an n-type amorphous silicon-based material.

[0105] The second transition layer 132 may be located on the side of the n-type doped layer 13 away from the substrate 11. The second transition layer 132 has a first doping type. As an example, the first doping type may be N-type doping. In this case, the second transition layer 132 may be an N-type amorphous buffer layer. Further, the thickness of the second transition layer 132 is 2 nm to 7 nm.

[0106] In this embodiment, firstly, the hydrogen content in the second transition layer 132 is greater than the hydrogen content in the n-type doped layer 13, which enables the second transition layer 132 to better contact with the first transparent conductive layer 133. It can be understood that when preparing the second transition layer 132 and the first transparent conductive layer 133, the hydrogen in the second transition layer 132 can provide sufficient hydrogen during the growth process of the first transparent conductive layer 133 to passivate the defects of the first transparent conductive layer 133, thereby improving the conductivity of the first transparent conductive layer 133 and improving the efficiency of the heterojunction solar cell 10. Secondly, the lattice constant and the interplanar spacing of the first transparent conductive layer 133 are greatly different from those of the n-type doped layer 13. In this embodiment, by setting the second transition layer 132 in the first transparent conductive layer 133 and the n-type doped layer 13, the second transition layer 132 relieves the lattice mismatch between the first transparent conductive layer 133 and the n-type doped layer 13, relieves the stress between the first transparent conductive layer 133 and the n-type doped layer 13, avoids the defects and transmission barriers caused by the lattice mismatch between the first transparent conductive layer 133 and the n-type doped layer 13, improves the transmission and passivation contact of carriers, reduces the generation of interface states, and improves the transmission and collection of carriers. In addition, in this embodiment, the second transition layer 132 also has a photoelectric conversion function, which can reduce the demand for the thickness of the n-type doped layer 13, reduce the coating time of the n-type doped layer 13, help to improve the production capacity of large-scale mass production of heterojunction batteries, and reduce equipment costs. Afterwards, in this embodiment, the first transition layer 131, the n-type doped layer 13, and the second transition layer 132 all have the first doping type, which makes the potential barrier between the multiple film layers on this side smaller, which is conducive to the improvement of photoelectric conversion efficiency. Furthermore, in this embodiment, the n-type doped layer 13 is provided to connect the second transition layer 132 , which can alleviate the disadvantage of insufficient lateral transmission of the n-type doped layer 13 , improve the contact between the entire N layer and the first transparent conductive layer 133 , and improve the series resistance of the heterojunction solar cell 10 .

[0107] In one embodiment, the heterojunction solar cell 10 further includes: at least one third transition layer 121 located between the p-type doped layer 12 and the second transparent conductive layer 123 , and the material of the third transition layer 121 is an n-type microcrystalline silicon-based material.

[0108] See also Figure 2 , the third transition layer 121 may be located on the side of the p-type doped layer 12 away from the substrate 11. The third transition layer 121 has a first doping type. As an example, the first doping type may be N-type doping. In this case, the third transition layer 121 may be an N-type microcrystalline layer.

[0109] In this embodiment, firstly, the p-type doping layer 12 and the third transition layer 121 that are in contact with each other are provided with different doping types, respectively. At this time, the third transition layer 121 can improve the tunneling contact of the carrier collection of the p-type doping layer 12, reduce the barrier of the carrier transmission of the p-type doping layer 12, thereby effectively improving the conversion efficiency of the heterojunction solar cell 10. For example, when the p-type doping layer 12 is a P-type microcrystalline layer, the third transition layer 121 can improve the tunneling contact of the hole collection of the P-type microcrystalline layer. Secondly, in this embodiment, the p-type doping layer 12 and the third transition layer 121 are both microcrystalline layers. At this time, compared with the amorphous layer in the conventional technology, the photoelectric conversion efficiency of the p-type doping layer 12 and the third transition layer 121 is better, and the stability of the heterojunction solar cell 10 is better. Afterwards, the p-type doping layer 12 has the second doping type, and the third transition layer 121 has the first doping type, so that the collection of hole carriers can be improved.

[0110] In one embodiment, the heterojunction solar cell 10 further includes: at least one fourth transition layer 122 located between the third transition layer 121 and the second transparent conductive layer 123 , and the material of the fourth transition layer 122 is an n-type amorphous silicon-based material.

[0111] The heterojunction solar cell 10 may further include a fourth transition layer 122. The fourth transition layer 122 is located on the side of the third transition layer 121 away from the substrate 11. The fourth transition layer 122 has a first doping type. For example. The fourth transition layer 122 is an amorphous N-type buffer layer. The fourth transition layer 122 and the third transition layer 121 may be doped with the same ions. For example, the fourth transition layer 122 and the third transition layer 121 may be doped with phosphorus. Of course, the fourth transition layer 122 and the third transition layer 121 may be doped with different ions. For example, the fourth transition layer 122 may be doped with phosphorus, and the third transition layer 121 may be doped with arsenic.

[0112] The refractive index of the third transition layer 121 may be less than the refractive index of the fourth transition layer 122. The thickness of the p-type doped layer 12 may be greater than the thickness of the fourth transition layer 122, and the thickness of the third transition layer 121 may also be greater than the thickness of the p-type doped layer 12. At this time, by setting the thickness, refractive index and other parameters of the p-type doped layer 12, the third transition layer 121 and the fourth transition layer 122, a better photoelectric conversion efficiency can be obtained. As an example, the film thickness of the p-type doped layer 12 may be in the range of 18nm to 24nm, and the refractive index of the p-type doped layer 12 may be between 3.20 and 3.60. The thickness of the third transition layer 121 may be between 3nm and 7nm, and the refractive index of the third transition layer 121 may be between 3.20 and 3.60. The film thickness of the fourth transition layer 122 may be between 2nm and 7nm, and the refractive index of the fourth transition layer 122 may be between 3.90 and 4.20.

[0113] It can be understood that in this embodiment, the p-type doped layer 12 can have the second doping type, and the third transition layer 121 and the fourth transition layer 122 can have the first doping type. For example, the p-type doped layer 12 can be P-type doped, and the third transition layer 121 and the fourth transition layer 122 can be N-type doped.

[0114] In this embodiment, the hydrogen content in the fourth transition layer 122 is greater than the hydrogen content in the p-type doped layer 12, so that the fourth transition layer 122 can better contact with the second transparent conductive layer 123, passivate the defects of the second transparent conductive layer 123 during the formation of the second transparent conductive layer 123, and improve the growth of the second transparent conductive layer 123. It can be understood that when preparing the fourth transition layer 122 and the second transparent conductive layer 123, the hydrogen in the fourth transition layer 122 can provide sufficient hydrogen to passivate the defects of the second transparent conductive layer 123 during the growth of the second transparent conductive layer 123, thereby improving the conductivity of the second transparent conductive layer 123 and improving the efficiency of the heterojunction solar cell 10. Again, the lattice constant and interplanar spacing of the second transparent conductive layer 123 are greatly different from those of the p-type doped layer 12. In this embodiment, by setting the fourth transition layer 122 in the second transparent conductive layer 123 and the p-type doped layer 12, the fourth transition layer 122 relieves the lattice mismatch between the second transparent conductive layer 123 and the p-type doped layer 12, relieves the stress between the second transparent conductive layer 123 and the p-type doped layer 12, avoids the defects and transmission barriers caused by the lattice mismatch between the second transparent conductive layer 123 and the p-type doped layer 12, improves the transmission and passivation contact of carriers, reduces the generation of interface states, and also improves the transmission and collection of carriers. Therefore, in this embodiment, the fourth transition layer 122 also has a photoelectric conversion function, which can reduce the demand for the thickness of the p-type doped layer 12, reduce the coating time of the p-type doped layer 12, help to improve the production capacity of large-scale mass production of heterojunction batteries, and reduce equipment costs.

[0115] In one possible example, the thickness of the n-type doping layer 13 is greater than the thickness of the first transition layer 131, and / or, the thickness of the n-type doping layer 13 is greater than the thickness of the second transition layer 132. It can be understood that the n-type doping layer 13 can be greater than the thickness of the first transition layer 131 and the thickness of the second transition layer 132, respectively, to increase the photoelectric conversion efficiency. In another possible example, the thickness of the second transition layer 132 is consistent with the thickness of the first transition layer 131, thereby reducing the difficulty of preparing the second transition layer 132 and the first transition layer 131. In another possible example, the thickness of the p-type doping layer 12 is greater than the thickness of the n-type doping layer 13. The first transition layer 131 is arranged between the n-type doping layer 13 and the substrate, thereby reducing the thickness of the n-type doping layer 13 and shortening the preparation time of the n-type doping layer 13. In another possible example, the refractive index of the second transition layer 132 is greater than the refractive index of the n-type doping layer 13, thereby increasing the light transmittance of the heterojunction solar cell 10. For example, the film thickness of the n-type doped layer 13 can be between 8 nm and 14 nm, and the refractive index of the n-type doped layer 13 can be between 2.40 and 3.00. The thickness of the first transition layer 131 and the second transition layer 132 can be between 1 nm and 5 nm, and the refractive index of the first transition layer 131 and the second transition layer 132 can be between 3.90 and 4.20.

[0116] Please refer to the following table, which shows a plurality of test data of the heterojunction solar cell 10 obtained after testing the heterojunction solar cell 10 provided in one or more embodiments of the present application. The test parameters include conversion efficiency, open circuit voltage, short circuit current, fill factor, series resistance and pseudo fill factor (pFF).

[0117]

[0118] It can be seen from the above table that after adding the first transition layer 131, the second transition layer 132, the third transition layer 121 and the fourth transition layer 122, multiple parameters of the heterojunction solar cell 10 are improved. For example, when the thickness of the n-type doping layer is reduced to 12nm, the open circuit voltage of the heterojunction solar cell 10 is low and the series resistance is large. For example, after adding the fourth transition layer 122 and the second transition layer 132 of 4nm respectively, the open circuit voltage and series resistance of the heterojunction solar cell 10 are significantly improved, and the conversion efficiency of the heterojunction solar cell 10 is increased by 0.46%. For example, after adding the third transition layer 121 of 5nm on the side of the 22nm p-type doping layer 12 away from the substrate, the series resistance of the heterojunction solar cell 10 is further reduced to 1.06Ω, and the conversion efficiency of the heterojunction solar cell 10 is increased by 0.14%. Finally, by using the heterojunction solar cell 10 provided in one or more embodiments of the present application, the conversion efficiency of the heterojunction solar cell 10 reaches 25.74%.

[0119] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", "ideal embodiments", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic descriptions of the above terms do not necessarily refer to the same embodiment or example. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. It should be understood that "this embodiment" or "one embodiment" mentioned throughout the specification means that the specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present disclosure. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification may not necessarily refer to the same embodiment.

[0120] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features of the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0121] The embodiments described above only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all fall within the scope of protection of the present application. Therefore, the scope of protection of the patent of the present application shall be subject to the attached claims. The above description is only a preferred implementation method of the present disclosure, and does not limit the scope of the patent of the present disclosure. All equivalent structural transformations made by using the contents of the present disclosure specification and drawings under the inventive concept of the present disclosure, or direct / indirect application in other related technical fields are included in the scope of protection of the patent of the present disclosure.

Claims

1. A method for preparing a heterojunction solar cell, characterized in that: include: Providing a substrate, the substrate comprising a first surface and a second surface disposed opposite to each other; forming at least one first intrinsic passivation layer and at least one second intrinsic passivation layer on the first surface and the second surface of the substrate respectively; forming at least one first transition layer on the first intrinsic passivation layer, wherein the material of the first transition layer is an n-type amorphous silicon-based material; forming at least one n-type doped layer on the first transition layer; forming at least one p-type doped layer on the second intrinsic passivation layer; forming at least one first transparent conductive layer and at least one second transparent conductive layer on the n-type doping layer and the p-type doping layer, respectively; A first electrode and a second electrode are formed on the first transparent conductive layer and the second transparent conductive layer, respectively.

2. The method for preparing a heterojunction solar cell according to claim 1, characterized in that: Before forming at least one first transparent conductive layer and at least one second transparent conductive layer on the n-type doping layer and the p-type doping layer respectively, the method comprises: At least one second transition layer is formed on the n-type doped layer, wherein the material of the second transition layer is an n-type amorphous silicon-based material.

3. The method for preparing a heterojunction solar cell according to claim 1, characterized in that: Before forming at least one first transparent conductive layer and at least one second transparent conductive layer on the n-type doping layer and the p-type doping layer respectively, the method comprises: At least one third transition layer is formed on the p-type doped layer, and the material of the third transition layer is an n-type microcrystalline silicon-based material.

4. The method for preparing a heterojunction solar cell according to claim 3, characterized in that: The material of the third transition layer is n-type oxygen-doped microcrystalline silicon-based material.

5. The method for preparing a heterojunction solar cell according to claim 3, characterized in that: Before forming at least one first transparent conductive layer and at least one second transparent conductive layer on the n-type doping layer and the p-type doping layer respectively, the method comprises: At least one fourth transition layer is formed on the third transition layer, and the material of the fourth transition layer is an n-type amorphous silicon-based material.

6. The method for preparing a heterojunction solar cell according to any one of claims 1 to 5, characterized in that: The materials of the n-type doping layer and the p-type doping layer are microcrystalline silicon-based materials.

7. A heterojunction solar cell, characterized in that: include: A substrate having a first surface and a second surface disposed opposite to each other; at least one first intrinsic passivation layer disposed on the first surface of the substrate; At least one first transition layer, located on a side of the first intrinsic passivation layer away from the substrate, wherein the material of the first transition layer is an n-type amorphous silicon-based material; at least one n-type doped layer, located on the first transition layer; at least one first transparent conductive layer, located on the n-type doped layer; at least one first electrode, located on the first transparent conductive layer; at least one second intrinsic passivation layer disposed on the second surface of the substrate; at least one p-type doped layer, located on a side of the second intrinsic passivation layer away from the substrate; at least one second transparent conductive layer, located on the p-type doped layer; At least one second electrode is located on the second transparent conductive layer.

8. The heterojunction solar cell according to claim 7, characterized in that: The heterojunction solar cell further includes: at least one second transition layer located between the n-type doped layer and the first transparent conductive layer, wherein the material of the second transition layer is an n-type amorphous silicon-based material.

9. The heterojunction solar cell according to claim 8, characterized in that: The thickness of the first transition layer is 2nm-7nm, and / or the thickness of the second transition layer is 2nm-7nm.

10. The heterojunction solar cell according to claim 9, characterized in that: The heterojunction solar cell further includes: at least one third transition layer located between the p-type doped layer and the second transparent conductive layer, wherein the material of the third transition layer is an n-type microcrystalline silicon-based material.

11. The heterojunction solar cell according to claim 10, characterized in that: The material of the third transition layer is n-type oxygen-doped microcrystalline silicon-based material.

12. The heterojunction solar cell according to claim 10, characterized in that: The heterojunction solar cell further includes: at least one fourth transition layer located between the third transition layer and the second transparent conductive layer, wherein the material of the fourth transition layer is an n-type amorphous silicon-based material.

13. The heterojunction solar cell according to claim 12, characterized in that: The thickness of the third transition layer is 3 nm to 7 nm, and / or the thickness of the fourth transition layer is 2 nm to 7 nm.

14. The heterojunction solar cell according to any one of claims 7 to 13, characterized in that: The materials of the n-type doping layer and the p-type doping layer are microcrystalline silicon-based materials.

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