CN117790590A - Passivation film, passivation film preparation method and solar cell - Google Patents
Passivation film, passivation film preparation method and solar cell Download PDFInfo
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- 238000002161 passivation Methods 0.000 title claims abstract description 479
- 238000002360 preparation method Methods 0.000 title claims abstract description 16
- 230000000694 effects Effects 0.000 claims abstract description 102
- 239000000758 substrate Substances 0.000 claims abstract description 63
- 238000006388 chemical passivation reaction Methods 0.000 claims abstract description 41
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 31
- 229910052739 hydrogen Inorganic materials 0.000 claims description 31
- 239000001257 hydrogen Substances 0.000 claims description 31
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 27
- 239000000463 material Substances 0.000 claims description 18
- 238000000034 method Methods 0.000 claims description 6
- 239000000969 carrier Substances 0.000 abstract description 7
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- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 18
- 238000006243 chemical reaction Methods 0.000 description 18
- 239000004065 semiconductor Substances 0.000 description 10
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 7
- 229910052710 silicon Inorganic materials 0.000 description 7
- 239000010703 silicon Substances 0.000 description 7
- 238000005538 encapsulation Methods 0.000 description 6
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 5
- 238000000231 atomic layer deposition Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 5
- 229910052814 silicon oxide Inorganic materials 0.000 description 5
- 229910052581 Si3N4 Inorganic materials 0.000 description 4
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- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 description 4
- 238000003491 array Methods 0.000 description 3
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- JLTRXTDYQLMHGR-UHFFFAOYSA-N trimethylaluminium Chemical compound C[Al](C)C JLTRXTDYQLMHGR-UHFFFAOYSA-N 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 2
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
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- 238000005516 engineering process Methods 0.000 description 2
- 229910021421 monocrystalline silicon Inorganic materials 0.000 description 2
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- 229910052709 silver Inorganic materials 0.000 description 2
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- JBRZTFJDHDCESZ-UHFFFAOYSA-N AsGa Chemical compound [As]#[Ga] JBRZTFJDHDCESZ-UHFFFAOYSA-N 0.000 description 1
- 229910001218 Gallium arsenide Inorganic materials 0.000 description 1
- YZCKVEUIGOORGS-UHFFFAOYSA-N Hydrogen atom Chemical compound [H] YZCKVEUIGOORGS-UHFFFAOYSA-N 0.000 description 1
- GPXJNWSHGFTCBW-UHFFFAOYSA-N Indium phosphide Chemical compound [In]#P GPXJNWSHGFTCBW-UHFFFAOYSA-N 0.000 description 1
- 229910000577 Silicon-germanium Inorganic materials 0.000 description 1
- LEVVHYCKPQWKOP-UHFFFAOYSA-N [Si].[Ge] Chemical compound [Si].[Ge] LEVVHYCKPQWKOP-UHFFFAOYSA-N 0.000 description 1
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- AJNVQOSZGJRYEI-UHFFFAOYSA-N digallium;oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Ga+3].[Ga+3] AJNVQOSZGJRYEI-UHFFFAOYSA-N 0.000 description 1
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- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
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Abstract
The application relates to a passivation film, a passivation film preparation method and a solar cell, wherein the passivation film comprises two layers of passivation layers, a first passivation layer is arranged on the surface of a substrate, a second passivation layer is arranged on the surface of the first passivation layer, which is away from the substrate, the field passivation effect of the first passivation layer is superior to that of the second passivation layer, namely, the field passivation effect of the film layer close to the substrate is superior to that of the uppermost field passivation effect, charge carriers with similar polarity can be prevented from approaching the substrate, the number of carriers with one polarity reaching the surface is greatly reduced, and the composite loss of the surface of the substrate is remarkably reduced. The chemical passivation effect of the second passivation layer is better than that of the first passivation layer, the chemical passivation effect of the upper surface film layer of the outermost layer of the passivation film is optimal, and atoms have enough time and energy to reach the optimal energy level, so that surface dangling bonds are saturated, the composite effect of the surface dangling bonds on other positive and negative charges is reduced, and the passivation effect of the passivation film is ensured. Namely, the passivation film can give consideration to both field passivation effect and chemical passivation effect.
Description
Technical Field
The application relates to the technical field of solar cells, in particular to a passivation film, a passivation film preparation method and a solar cell.
Background
The conversion efficiency of a solar cell is an important parameter for the performance of the solar cell. In order to improve the conversion efficiency of a solar cell, a passivation film is generally prepared by adopting a passivation technology in the solar cell preparation process in the solar cell technical field, however, a traditional passivation film cannot simultaneously ensure higher fixed charge density and hydrogen atom percentage content, and it is difficult to combine a field passivation effect and a chemical passivation effect.
Disclosure of Invention
In view of the foregoing, it is desirable to provide a passivation film, a passivation film manufacturing method, and a solar cell that can achieve both field passivation effect and chemical passivation effect.
In a first aspect, the present application provides a passivation film comprising:
the first passivation layer is arranged on the surface of the substrate;
the second passivation layer is arranged on the surface of the first passivation layer, which is away from the substrate;
the field passivation effect of the first passivation layer is better than that of the second passivation layer, and the chemical passivation effect of the second passivation layer is better than that of the first passivation layer.
In one embodiment, the negative charge density of the first passivation layer is greater than the negative charge density of the second passivation layer.
In one embodiment, the hydrogen content of the second passivation layer is greater than the hydrogen content of the first passivation layer.
In one embodiment, the first passivation layer has a first thickness that is less than a second thickness of the second passivation layer.
In one embodiment, the method further comprises:
the third passivation layer is arranged on the surface, away from the first passivation layer, of the second passivation layer, and the negative charge density of the third passivation layer is smaller than that of the first passivation layer and larger than that of the second passivation layer;
the hydrogen content of the third passivation layer is less than the hydrogen content of the second passivation layer and greater than the hydrogen content of the first passivation layer.
In one embodiment, the thickness of the first passivation layer is 15% -25% of the passivation film thickness; the passivation film thickness is a sum of thicknesses of the first passivation layer, the second passivation layer, and the third passivation layer.
In one embodiment, the second passivation layer has a thickness less than a thickness of the third passivation layer.
In one embodiment, the first passivation layer, the second passivation layer and the third passivation layer are made of the same material.
In one embodiment, the materials of the first passivation layer, the second passivation layer and the third passivation layer are all alumina.
In a second aspect, the present application further provides a passivation film preparation method for preparing a passivation film as described above; the method comprises the following steps:
forming a first passivation layer on the surface of the substrate;
forming a second passivation layer on the surface of the first passivation layer facing away from the substrate;
the field passivation effect of the first passivation layer is better than that of the second passivation layer, and the chemical passivation effect of the second passivation layer is better than that of the first passivation layer.
In a third aspect, the present application also provides a solar cell, comprising:
a substrate;
the passivation film is arranged on the surface of the substrate.
According to the passivation film, the passivation film preparation method and the solar cell, the passivation film comprises two layers of passivation layers, wherein the first passivation layer is arranged on the surface of the substrate, the second passivation layer is arranged on the surface of the first passivation layer, which is away from the substrate, the field passivation effect of the first passivation layer is superior to that of the second passivation layer, namely, the field passivation effect of the film layer close to the substrate is superior to that of the uppermost field passivation effect, and charge carriers with similar polarity can be prevented from approaching the substrate, so that the number of carriers with one polarity reaching the surface is greatly reduced, and the composite loss of the surface of the substrate is remarkably reduced. The chemical passivation effect of the second passivation layer is better than that of the first passivation layer, the chemical passivation effect of the upper surface film layer of the outermost layer of the passivation film is optimal, and atoms have enough time and energy to reach the optimal energy level, so that surface dangling bonds are saturated, the composite effect of the surface dangling bonds on other positive and negative charges is reduced, and the passivation effect of the passivation film is ensured. In the application, the field passivation effect of the first passivation layer is better than that of the second passivation layer, and the chemical passivation effect of the second passivation layer is better than that of the first passivation layer, so that the field passivation effect and the chemical passivation effect of the whole passivation film are improved, and the field passivation effect and the chemical passivation effect of the passivation film are both considered.
Drawings
FIG. 1 is a schematic diagram of a passivation film structure according to one embodiment;
FIG. 2 is a schematic diagram of a passivation film according to a second embodiment;
FIG. 3 is a third schematic diagram of a passivation film according to one embodiment;
fig. 4 is a schematic flow chart of a passivation film preparation method in an embodiment.
Reference numerals illustrate:
10. a passivation layer; 11. a first passivation layer; 111. a first aluminum oxide layer; 12. a second passivation layer; 121. a second aluminum oxide layer; 13. and a third passivation layer.
Detailed Description
In order to facilitate an understanding of the present application, a more complete description of the present application will now be provided with reference to the relevant figures. Preferred embodiments of the present application are shown in the drawings. This application may, however, be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
It will be understood that when an element or layer is referred to as being "on," "adjacent," "connected to," or "coupled to" another element or layer, it can be directly on, adjacent, connected, or coupled to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" another element or layer, there are no intervening elements or layers present. It will be understood that, although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers, doping types and/or sections, these elements, components, regions, layers, doping types and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, doping type or section from another element, component, region, layer, doping type or section.
Spatially relative terms, such as "under", "below", "beneath", "under", "above", "over" and the like, may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use and operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements or features described as "under" or "beneath" other elements would then be oriented "on" the other elements or features. Thus, the exemplary terms "below" and "under" may include both an upper and a lower orientation. Furthermore, the device may also include an additional orientation (e.g., rotated 90 degrees or other orientations) and the spatial descriptors used herein interpreted accordingly.
As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. Also, as used herein, the term "and/or" includes any and all combinations of the associated listed items.
Embodiments of the invention are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of the present application, such that variations of the illustrated shapes due to, for example, manufacturing techniques and/or tolerances are to be expected. Thus, embodiments of the present application should not be limited to the particular shapes of regions illustrated herein, but rather include deviations in shapes that result, for example, from manufacturing techniques. For example, an implanted region shown as a rectangle typically has rounded or curved features and/or implant concentration gradients at its edges rather than a binary change from implanted to non-implanted regions. Also, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface over which the implantation is performed. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the present application.
The embodiment of the application provides a passivation film, which is formed on the surface of a substrate and is used for improving the passivation effect of the passivation film. Further, based on the application scene of the passivation film, the performance of the semiconductor device, such as a photovoltaic cell, a semiconductor light-emitting device and the like, can be improved. Wherein the photovoltaic cell may in turn be a solar cell. In this application, explanation will be made taking application of a passivation film to a solar cell as an example.
Specifically, the solar cell is a photoelectric semiconductor sheet which directly generates electricity by utilizing sunlight, namely a solar chip or a photocell, under the condition of certain illuminance, sunlight irradiates on a p-n junction of a semiconductor to form a new hole-electron pair, under the action of an electric field built in the p-n junction, photo-generated holes flow to a p region, photo-generated electrons flow to an n region, and current is generated after a circuit is connected, so that the cell can output voltage and generate current under the condition of a loop. In the process of preparing a solar cell, the problem of passivation of the surface of a substrate is generally solved by synthesizing a passivation film, and the principle comprises two aspects: firstly, atoms generated in the passivation film are combined with dangling bonds, so that the composite action of the atoms on other positive and negative charges is reduced, and a chemical passivation effect is formed; and secondly, certain charges exist in the passivation film, and a built-in electric field is formed on the contact surface, so that a field passivation effect is formed. The core function of the photoelectric conversion device is to improve the open-circuit voltage and the short-circuit current, further improve the filling factor and further improve the photoelectric conversion efficiency.
In one embodiment, the present application provides a passivation film 10, as shown in one of the schematic structural diagrams of the passivation film 10 in fig. 1, where the passivation film 10 includes a first passivation layer 11 and a second passivation layer 12, and the first passivation layer 11 is disposed on the surface of the substrate; the second passivation layer 12 is arranged on the surface of the first passivation layer 11 facing away from the substrate; wherein, the field passivation effect of the first passivation layer 11 is better than the field passivation effect of the second passivation layer 12, and the chemical passivation effect of the second passivation layer 12 is better than the chemical passivation effect of the first passivation layer 11.
The substrate may be a semiconductor substrate made of silicon, germanium, or the like, or a compound semiconductor substrate made of silicon carbide, silicon germanium, gallium arsenide, indium phosphide, zinc oxide, gallium oxide, or the like. As an example, in the present embodiment, a single crystal silicon is selected as a constituent material of the substrate. The substrate comprises a light receiving surface and a back surface which are oppositely arranged. The substrate surface may be a light receiving surface that receives sunlight irradiation, or may be a backlight surface that faces the light receiving surface.
The materials of the first passivation layer 11 and the second passivation layer 12 may be one or two of silicon oxide, aluminum oxide, silicon nitride, silicon oxynitride, and silicon oxycarbonitride, respectively, that is, the materials of the first passivation layer 11 and the second passivation layer 12 may be the same or different. For the first passivation layer 11 and the second passivation layer 12 made of different materials, the passivation principle of the formed passivation film 10 is different from that of the passivation film 10 formed by the first passivation layer 11 and the second passivation layer 12 made of the same materials, for example, if the first passivation layer 11 is an aluminum oxide film layer and the second passivation layer 12 is a silicon oxide film layer, at this time, the passivation film 10 formed by the first passivation layer 11 and the second passivation layer 12 is a composite passivation film 10, and the aluminum oxide film layer and the silicon oxide film layer can passivate dangling bonds on the surface of the substrate by adding atomic hydrogen, so that the hydrogen passivation effect is ensured, and the chemical passivation performance is improved. When the first passivation layer 11 and the second passivation layer 12 are made of the same material, for example, silicon oxide films, the field passivation effect and the chemical passivation effect of the two passivation layers may be different in this embodiment, so that the field passivation effect and the chemical passivation effect of the passivation layers are ensured at the same time, and the passivation effect of the passivation film 10 is integrally improved. For another example, if two passivation layers are both silicon nitride film layers, the refractive indexes of the range silicon nitride film layers can be set to be different, so that the anti-reflection effect of the passivation film 10 is improved. It will be appreciated that the above examples are only examples for facilitating understanding of the present embodiment, and are not specific limitations on the two passivation layers, and in other examples, in order to achieve effects similar to the present embodiment, passivation layers made of different materials may be provided so that the field passivation effect and the chemical passivation effect of each passivation layer are different.
In this embodiment, a passivation film 10 is provided, which includes two passivation layers, wherein a first passivation layer 11 is disposed on the surface of a substrate, a second passivation layer 12 is disposed on the surface of the first passivation layer 11 facing away from the substrate, and the field passivation effect of the first passivation layer 11 is better than that of the second passivation layer 12, that is, the field passivation effect of the film layer close to the substrate is better than that of the uppermost field passivation effect, so that charge carriers with similar polarity can be prevented from approaching the substrate, thereby greatly reducing the number of carriers with one polarity reaching the surface, and significantly reducing the recombination loss on the surface of the substrate. The chemical passivation effect of the second passivation layer 12 is better than the first passivation effect, and the chemical passivation effect of the upper surface film layer of the outermost layer of the passivation film 10 is optimal, so that atoms have enough time and energy to reach the optimal energy level, thereby saturating the surface dangling bond, reducing the composite effect of the surface dangling bond on other positive and negative charges, and ensuring the passivation effect of the passivation film 10. That is, in this embodiment, the field passivation effect of the first passivation layer 11 is better than the field passivation effect of the second passivation layer 12, and the chemical passivation effect of the second passivation layer 12 is better than the chemical passivation effect of the first passivation layer 11, so that the field passivation effect and the chemical passivation effect of the passivation film 10 are improved, and the field passivation effect and the chemical passivation effect of the passivation film 10 are ensured.
In one embodiment, the negative charge density of the first passivation layer is greater than the negative charge density of the second passivation layer. Specifically, the higher the negative charge density of the contact surface of the passivation layer and the substrate, the stronger the capability of shielding minority carriers on the surface of the substrate, thus having better field passivation effect. The negative charge density of the first passivation layer may be greater than 2×10 12 cm -2 And is greater than the negative charge density of the second passivation layer. In other examples, the negative charge density of the first passivation layer may also be greater than 2.1X10 12 cm -2 、2.2×10 12 cm -2 、2.3×10 12 cm -2 、2.4×10 12 cm -2 、2.5×10 12 cm -2 、3×10 12 cm -2 、3.5×10 12 cm -2 And the like, without being limited thereto.
In this embodiment, by setting the negative charge density of the first passivation layer to be greater than the negative charge density of the second passivation layer, the passivation effect of the first passivation layer close to the surface of one side of the substrate is better than the passivation effect of the second passivation layer on the surface of one side of the first passivation layer, so that the field passivation effect of the passivation film can be more effectively ensured, and the photoelectric conversion efficiency of the solar cell is further improved.
In one embodiment, the hydrogen content of the second passivation layer is greater than the hydrogen content of the first passivation layer. Specifically, the higher the hydrogen content of the upper surface of the passivation film, the stronger its ability to reduce the recombination of dangling bonds to other positive and negative charges, and thus has a better chemical passivation effect. Illustratively, the hydrogen content of the second passivation layer may be greater than 3% and greater than the hydrogen content of the first passivation layer. In other examples, the hydrogen content of the second passivation layer may also be greater than 3.1%, 3.2%, 3.3%, 3.4%, 4%, 5%, etc., without being limited thereto.
In the embodiment, the hydrogen content of the second passivation layer is larger than that of the first passivation layer, so that the chemical passivation effect of the second passivation layer on the surface of the first passivation layer, which faces away from the substrate, is better than that of the first passivation layer, on one hand, the chemical passivation effect of the passivation film can be effectively ensured, and further the photoelectric conversion efficiency of the solar cell is improved; on the other hand, the first passivation layer has less hydrogen content, and can also effectively avoid the occurrence of the rupture phenomenon, thereby improving the quality of the passivation film.
In one embodiment, the first thickness of the first passivation layer is less than the second thickness of the second passivation layer.
For convenience of explanation, the sum of thicknesses of the passivation films is referred to as passivation film thickness in the embodiments of the present application, where, in order to avoid the problem that the passivation layer, which is difficult to burn through by silver paste during the solar cell manufacturing process, reaches the substrate surface, the passivation film thickness is not too thick, and may be, for example, 1nm to 30nm. In other examples, it may be 2nm to 20nm, 3nm to 18nm, 4nm to 15nm, etc., without being limited thereto.
Specifically, the first thickness may be understood as a thickness of the first passivation layer when a sufficient field passivation effect is achieved on the substrate, and the second thickness may be understood as a thickness of the second passivation layer when a target chemical passivation effect is achieved on the basis that the first passivation layer achieves the sufficient field passivation effect. Further, according to different materials of the passivation layers, the corresponding thicknesses of the passivation layers when the field passivation effect/chemical passivation effect is optimal are different, and the first passivation layer and the second passivation layer are exemplified by alumina, wherein the alumina film layer has a saturation value when the fixed charge of the surface dielectric layer is increased and the field passivation effect reaches a peak value when the thickness of the alumina film layer is about 2nm; when the thickness of the alumina is more than about 10nm, the surface recombination rate is not reduced. Therefore, in this embodiment, the first thickness of the first passivation layer is set smaller than the second thickness of the second passivation layer, so that the field passivation effect and the chemical passivation effect of different passivation layers in the passivation film can be ensured at the same time. Illustratively, the thickness of the first passivation layer is 15% -25% of the passivation film thickness, for example, in the case of 4nm passivation film thickness, the first thickness of the first passivation layer is set to be 0.6 nm-1 nm, and the second thickness of the second passivation layer is set to be 3 nm-3.4 nm; if the passivation film thickness is 15nm, the first passivation layer is provided with a first thickness of 2.25nm to 3.75nm, the second passivation layer is provided with a second thickness of 11.25nm to 12.75nm, and the like, without being limited thereto.
In the embodiment, the first thickness of the first passivation layer is smaller than the second thickness of the second passivation layer, so that on one hand, the internal stress in the passivation film can be reduced, the thermal stress can be relieved, the electrical performance of the passivation film and the substrate is remarkably improved, and the photoelectric conversion efficiency of the solar cell is remarkably improved; on the other hand, the proper first thickness is selected according to the performance requirement of the passivation film, so that the difference value between the first thickness of the first passivation layer and the second thickness of the second passivation layer is a threshold value difference value, the passivation requirement of the passivation film is met, meanwhile, the first passivation layer and the second passivation layer are respectively prepared by adopting preparation processes with different preparation efficiencies, and therefore the whole preparation time of the passivation film and the passivation effect of the passivation film are compatible.
In one embodiment, as shown in the second schematic structural diagram of the passivation film 10 in fig. 2, the passivation film 10 further includes a third passivation layer 13, the third passivation layer 13 is disposed on the surface of the second passivation layer 12 facing away from the first passivation layer 11, and the negative charge density of the third passivation layer 13 is smaller than the negative charge density of the first passivation layer 11 and greater than the charge density of the second passivation layer 12; the hydrogen content of the third passivation layer 13 is smaller than the hydrogen content of the second passivation layer 12 and larger than the hydrogen content of the first passivation layer 11.
It is understood that the passivation film 10 further includes the third passivation layer 13 in this embodiment, and the thickness of the passivation film 10 in the previous embodiment is the sum of the thicknesses of the first passivation layer 11, the second passivation layer 12 and the third passivation layer 13. Similarly, the material of the third passivation layer 13 may be one of silicon oxide, aluminum oxide, silicon nitride, silicon oxynitride or silicon oxycarbonitride, which may be the same as or different from the material of the first passivation layer 11 and the second passivation layer 12.
In this embodiment, the third passivation layer 13 is disposed on the surface of the second passivation layer 12 facing away from the first passivation layer 11, the negative charge density of the third passivation layer 13 is smaller than the negative charge density of the first passivation layer 11 and larger than the charge density of the second passivation layer 12, so that the field passivation effect of the third passivation layer 13 is inferior to that of the first passivation layer 11 and better than that of the second passivation layer 12, and meanwhile, the hydrogen content of the third passivation layer 13 is smaller than that of the second passivation layer 12 and larger than that of the first passivation layer 11, so that the chemical passivation effect of the third passivation layer 13 is inferior to that of the second passivation layer 12 and because of the first passivation layer 11, the passivation effect of the whole passivation film 10 can be optimized by adding passivation layers with different passivation effects of the passivation film 10 on the surface of the second passivation layer 12 facing away from the first passivation film 10.
In one embodiment, the thickness of the first passivation layer is 15% to 25% of the passivation film thickness; the passivation film thickness is the sum of the thicknesses of the first passivation layer, the second passivation layer, and the third passivation layer. Specifically, in order to avoid the problem that the silver paste is difficult to burn through the passivation film while ensuring the passivation effect of the passivation film, the first thickness of the first passivation layer, the second thickness of the second passivation layer and the third thickness of the third passivation layer may be set to gradually increase, that is, the thickness of the second passivation layer is smaller than the thickness of the third passivation layer, so that the electrical performance of the passivation film and the substrate is improved, and the photoelectric conversion efficiency of the solar cell is remarkably improved. Illustratively, in the case where the passivation film thickness is 4nm, the first thickness of the first passivation layer is set to 0.6nm to 1nm, the second thickness of the second passivation layer is set to 1.2nm to 1.4nm, and the third thickness of the third passivation layer is set to 1.6nm to 2.2nm; if the passivation film thickness is 15nm, the first passivation layer is provided with a first thickness of 2.25nm to 3.75nm, the second passivation layer is provided with a second thickness of 4nm to 4.75nm, and the third passivation layer is provided with a third thickness of 7.25nm to 8nm, etc., but the present invention is not limited thereto.
In one embodiment, the first passivation layer, the second passivation layer, and the third passivation layer are the same material. Illustratively, the first passivation layer, the second passivation layer and the third passivation layer are all made of aluminum oxide. The interface between the alumina film layer and the substrate has lower interface defect state density and higher fixed negative charge density. The fixed negative charges induce a space charge region in a certain depth range on the surface of the semiconductor and form a built-in electric field, and the built-in electric field can make carriers (such as electrons) in the semiconductor difficult to approach the surface of the semiconductor, so that the possibility of recombination of interface defect states and carriers is reduced, and a field passivation effect is achieved. The aluminum oxide film contains higher hydrogen atom content, and the hydrogen atoms can form bonds with dangling bonds on the surface of the semiconductor, so that interface defect states are reduced, and a chemical passivation effect is achieved.
In one embodiment, as shown in fig. 3, the passivation film 10 further includes a first aluminum oxide layer 111 and a second aluminum oxide layer 121, the first aluminum oxide layer 111 is disposed on the surface of the substrate 20, the second aluminum oxide layer 121 is disposed on the surface of the first aluminum oxide layer 111 facing away from the substrate 20, the total thickness of the first aluminum oxide layer 111 and the second aluminum oxide layer 121 is 4nm to 15nm, the thickness of the first aluminum oxide layer 111 is 15% -25% of the total thickness of the first aluminum oxide layer 111 and the second aluminum oxide layer 121, the thickness of the second aluminum oxide layer 121 is 75-85% of the total thickness of the first aluminum oxide layer 111 and the second aluminum oxide layer 121, and the negative charge density of the first aluminum oxide layer 111 is greater than 2×10 12 cm-2 and higher than the negative charge density of the second alumina layer 121; the hydrogen content in the second alumina layer 121 is greater than 3% and higher than the hydrogen content in the first alumina layer 111.
In the present embodiment, the passivation film 10 includes a two-layer aluminum oxide layer structure. The negative charge density of the first alumina layer 111 disposed on the surface of the substrate 20 is higher than that of the second alumina layer 121 disposed on the surface of the first alumina layer 111 facing away from the substrate 20, so that the field passivation effect of the first alumina layer 111 is better, and the hydrogen content of the second alumina layer 121 is higher than that of the first alumina layer 111, so that the chemical passivation effect of the second alumina layer 121 is better. Combining the two alumina layers, the alumina passivation film 10 with excellent field passivation effect and chemical passivation effect can be obtained; in addition, the first aluminum oxide layer 111 has a small hydrogen content, and thus the occurrence of the popping phenomenon can be reduced, and the quality of the passivation film 10 can be improved.
In an embodiment, as shown in a schematic flow chart of the passivation film preparation method shown in fig. 4, and referring to fig. 1, the passivation film preparation method is used to prepare passivation 10 in any of the foregoing embodiments, and may generally be prepared by Atomic Layer Deposition (ALD) and plate-type PERC (Passivated Emitter Rear Contact, passivation emitter back contact), and in this embodiment, the passivation film 10 is prepared by using an atomic layer deposition technology for explanation, and the passivation film preparation method in this embodiment includes the following steps 402 to 404.
In step 402, a first passivation layer 11 is formed on the surface of the substrate 20.
Specifically, after the reaction chamber temperature of the atomic layer deposition system and the precursor (such as water and trimethylaluminum) are set, the substrate 20 is placed in the reaction chamber, trimethylaluminum is introduced into the reaction chamber at a first preset flow rate in a first preset time, water is introduced into the reaction chamber at a second preset flow rate in a second preset time after the reaction chamber is vacuumized, the reaction chamber is vacuumized again, and the steps are repeated for a first preset number of times to obtain the first passivation layer 11. The first preset time, the second preset time, the first preset flow, the second preset flow and the first preset times can be flexibly set according to an actual operation scene, and the embodiment is not limited in detail.
Step 404, forming a second passivation layer 12 on the surface of the first passivation layer 11 facing away from the substrate 20; wherein, the field passivation effect of the first passivation layer 11 is better than the field passivation effect of the second passivation layer 12, and the chemical passivation effect of the second passivation layer 12 is better than the chemical passivation effect of the first passivation layer 11.
Specifically, the temperature and the precursor of the reaction cavity of the atomic layer deposition system are reset according to actual needs, trimethylaluminum is introduced into the reaction cavity at a third preset flow rate within a third preset time on the basis of preparing the first passivation layer 11, water is introduced into the reaction cavity at a fourth preset flow rate within a fourth preset time after vacuumizing, vacuumizing is performed again on the reaction cavity, and the steps are repeated for a second preset number of times to obtain the second passivation layer 12. The third preset time, the fourth preset time, the third preset flow, the fourth preset flow and the second preset times can be flexibly set according to the actual operation scene, and are not particularly limited herein.
It should be understood that, although the steps in the flowcharts related to the embodiments described above are sequentially shown as indicated by arrows, these steps are not necessarily sequentially performed in the order indicated by the arrows. The steps are not strictly limited to the order of execution unless explicitly recited herein, and the steps may be executed in other orders. Moreover, at least some of the steps in the flowcharts described in the above embodiments may include a plurality of steps or a plurality of stages, which are not necessarily performed at the same time, but may be performed at different times, and the order of the steps or stages is not necessarily performed sequentially, but may be performed alternately or alternately with at least some of the other steps or stages.
Based on the passivation film and the passivation film preparation method, the embodiment also provides a solar cell with the passivation film with excellent field passivation effect and chemical passivation effect, wherein the solar cell comprises a substrate and the passivation film in any embodiment, and the passivation film is arranged on the surface of the substrate. The substrate is used for receiving incident light and generating photo-generated carriers. For example, in some embodiments, the solar cell is a bifacial cell, i.e., both surfaces of the substrate are configured to receive solar rays. The substrate may be a silicon substrate, and the material of the silicon substrate may include single crystal silicon, polycrystalline silicon, amorphous silicon, and microcrystalline silicon. The passivation film comprises a first passivation layer and a second passivation layer, and the first passivation layer is arranged on the surface of the substrate. The second passivation layer is arranged on the surface of the first passivation layer, which is away from the substrate, and the field passivation effect of the first passivation layer is better than that of the second passivation layer, and the chemical passivation effect of the second passivation layer is better than that of the first passivation layer.
In one embodiment, the negative charge density of the first passivation layer is greater than the negative charge density of the second passivation layer.
In one embodiment, the hydrogen content of the second passivation layer is greater than the hydrogen content of the first passivation layer.
In one embodiment, the first thickness of the first passivation layer is less than the second thickness of the second passivation layer.
In one embodiment, the thickness of the first passivation layer is 15% to 25% of the passivation film thickness; the passivation film thickness is the sum of the first thickness of the first passivation layer and the second thickness of the second passivation layer.
In one embodiment, the first passivation layer and the second passivation layer are made of the same material.
In one embodiment, the first passivation layer and the second passivation layer are both made of aluminum oxide.
In one embodiment, the passivation film further comprises a third passivation layer, the third passivation layer is arranged on the surface, facing away from the first passivation layer, of the second passivation layer, and the negative charge density of the third passivation layer is smaller than the negative charge density of the first passivation layer and is larger than the charge density of the second passivation layer; the hydrogen content of the third passivation layer is less than the hydrogen content of the second passivation layer and greater than the hydrogen content of the first passivation layer.
In one embodiment, the thickness of the second passivation layer is less than the thickness of the third passivation layer.
In one embodiment, the material of the third passivation layer is the same as the material of the first passivation layer and the second passivation layer.
In one embodiment, the third passivation layer, the second passivation layer and the first passivation layer are all made of aluminum oxide.
Correspondingly, the embodiment of the application also provides a photovoltaic module, which comprises a battery string, wherein the battery string is formed by connecting the solar battery provided by any one of the embodiments or a plurality of solar batteries provided with the passivation film by any one of the embodiments.
The photovoltaic module further comprises an encapsulation layer and a cover plate, wherein the encapsulation layer is used for covering the surface of the battery string, and the cover plate is used for covering the surface, far away from the battery string, of the encapsulation layer. The solar cells are electrically connected in whole or multiple pieces to form multiple cell strings, and the multiple cell strings are electrically connected in series and/or parallel. Specifically, in some embodiments, multiple battery strings may be electrically connected by conductive charges. The encapsulation layer covers the surface of the solar cell. The encapsulation layer may be, for example, an organic encapsulation film such as an ethylene-vinyl acetate copolymer film, a polyethylene octene co-elastomer film, or a polyethylene terephthalate film. The cover plate can be a glass cover plate, a plastic cover plate and the like with a light transmission function.
In one embodiment, the present application further provides a photovoltaic system, including the photovoltaic module in any of the above embodiments.
It will be appreciated that the photovoltaic system may be used in photovoltaic power plants, such as ground power plants, rooftop power plants, surface power plants, etc., as well as in devices or apparatus that utilize solar energy for generating electricity, such as consumer solar power sources, solar street lamps, solar automobiles, solar buildings, etc. Of course, it is understood that the application scenario of the photovoltaic system is not limited thereto, that is, the photovoltaic system may be applied to all fields where solar energy is required to generate electricity. Taking a photovoltaic power generation system network as an example, the photovoltaic system can comprise a photovoltaic array, a confluence box and an inverter, wherein the photovoltaic array can be an array combination of a plurality of photovoltaic modules, for example, the photovoltaic modules can form a plurality of photovoltaic arrays, the photovoltaic arrays are connected with the confluence box, the confluence box can confluence currents generated by the photovoltaic arrays, and the confluence currents flow through the inverter to be converted into alternating currents required by a commercial power grid and then are connected with the commercial power network so as to realize solar power supply.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples only represent a few embodiments of the present application, which are described in more detail and are not to be construed as limiting the scope of the present application. It should be noted that it would be apparent to those skilled in the art that various modifications and improvements could be made without departing from the spirit of the present application, which would be within the scope of the present application. Accordingly, the scope of protection of the present application shall be subject to the appended claims.
Claims (11)
1. A passivation film, characterized in that the passivation film comprises:
the first passivation layer is arranged on the surface of the substrate;
the second passivation layer is arranged on the surface of the first passivation layer, which is away from the substrate;
the field passivation effect of the first passivation layer is better than that of the second passivation layer, and the chemical passivation effect of the second passivation layer is better than that of the first passivation layer.
2. The passivation film of claim 1, wherein the negative charge density of the first passivation layer is greater than the negative charge density of the second passivation layer.
3. The passivation film of claim 1, wherein the second passivation layer has a hydrogen content greater than the first passivation layer.
4. The passivation film of claim 1, wherein the first thickness of the first passivation layer is less than the second thickness of the second passivation layer.
5. A passivation film according to claim 1, further comprising:
the third passivation layer is arranged on the surface, away from the first passivation layer, of the second passivation layer, and the negative charge density of the third passivation layer is smaller than that of the first passivation layer and larger than that of the second passivation layer;
the hydrogen content of the third passivation layer is less than the hydrogen content of the second passivation layer and greater than the hydrogen content of the first passivation layer.
6. The passivation film according to claim 5, wherein the thickness of the first passivation layer is 15% to 25% of the passivation film thickness; the passivation film thickness is a sum of thicknesses of the first passivation layer, the second passivation layer, and the third passivation layer.
7. A passivation film according to claim 5, wherein the thickness of the second passivation layer is less than the thickness of the third passivation layer.
8. The passivation film according to claim 5, wherein the first passivation layer, the second passivation layer, and the third passivation layer are made of the same material.
9. The passivation film of claim 8, wherein the first passivation layer, the second passivation layer, and the third passivation layer are all aluminum oxide.
10. A passivation film preparation method, characterized by being used for preparing the passivation film according to any one of claims 1 to 9; the method comprises the following steps:
forming a first passivation layer on the surface of the substrate;
forming a second passivation layer on the surface of the first passivation layer facing away from the substrate;
the field passivation effect of the first passivation layer is better than that of the second passivation layer, and the chemical passivation effect of the second passivation layer is better than that of the first passivation layer.
11. A solar cell, comprising:
a substrate;
a passivation film according to any one of claims 1 to 9, the passivation film being provided on the substrate surface.
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