Double-sided tunneling passivation contact solar cell and preparation method thereof

Abstract

The invention provides a double-sided tunneling passivation contact solar cell and a preparation method thereof. The double-sided tunneling passivation contact solar cell comprises a first tunneling oxide layer, a boron-doped polycrystalline silicon layer, a first aluminum oxide layer, a first silicon nitride layer and a first grid electrode which are sequentially arranged on a first surface of a substrate and in a direction deviating from the first surface of the substrate, the second tunneling oxide layer, the phosphorus-doped polycrystalline silicon layer, the barrier layer, the second aluminum oxide layer, the second silicon nitride layer and the second grid electrode are located on the second face of the substrate and are arranged in the direction away from the second face of the substrate in sequence; wherein the barrier layer is configured to provide a positive charge. Thus, rich positive charges exist between the phosphorus-doped polycrystalline silicon layer and the second aluminum oxide layer, negative charges of the phosphorus-doped polycrystalline silicon layer and negative charges of the second aluminum oxide layer do not repel each other, carrier recombination is avoided, the passivation effect of the second aluminum oxide layer is improved, and then the photoelectric conversion efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of batteries, and in particular to a double-sided tunnel passivation contact solar cell and a preparation method thereof. Background Art

[0002] TOPCon (Tunneling Oxide Passivated Contact) solar cells have been widely produced and applied as a highly efficient solar crystalline silicon cell. Compared with traditional single-sided TOPCon cells, double-sided TOPCon cells have higher efficiency, lower temperature rise coefficient and lower attenuation rate. Therefore, double-sided TOPCon cells are expected to become the next generation mainstream cells.

[0003] Since the absorption coefficient of polycrystalline silicon in the visible light part is 1-2 orders of magnitude lower than that of amorphous silicon, it is beneficial to increase the photocurrent of the cell. Therefore, for double-sided TOPCon cells, doped polysilicon layers are often formed on both sides (one side is phosphorus-doped polysilicon layer, the other side is phosphorus-doped polysilicon layer), and then an aluminum oxide layer and other film layers are formed on the layer of the doped polysilicon layer away from the substrate. However, it is observed that the passivation effect of this double-sided TOPCon cell is poor and the photoelectric conversion efficiency is low. Summary of the invention

[0004] In order to solve the above problems, the inventors found the causes of the problems through research and development and formed solutions.

[0005] In a first aspect, the present invention provides a double-sided TOPCon solar cell, the double-sided TOPCon solar cell comprising:

[0006] substrate;

[0007] A first tunneling oxide layer, a boron-doped polysilicon layer, a first aluminum oxide layer, a first silicon nitride layer and a first gate are sequentially arranged on the first surface of the substrate and in a direction away from the first surface of the substrate;

[0008] A second tunneling oxide layer, a phosphorus-doped polysilicon layer, a barrier layer, a second aluminum oxide layer, a second silicon nitride layer and a second gate are sequentially arranged on the second surface of the substrate and in a direction away from the second surface of the substrate; wherein the barrier layer is configured to provide positive charge.

[0009] Furthermore, the above-mentioned double-sided TOPCon solar cell further comprises:

[0010] A transition layer is located between the phosphorus-doped polysilicon layer and the barrier layer.

[0011] Further, in the above-mentioned double-sided TOPCon solar cell, the transition layer comprises a phosphorus-doped polycrystalline silicon nitride layer;

[0012] The barrier layer includes a polycrystalline silicon nitride layer.

[0013] Furthermore, in the above-mentioned double-sided TOPCon solar cell, the first tunneling oxide layer and the second tunneling oxide layer have different material layers.

[0014] Further, in the above-mentioned double-sided TOPCon solar cell, the first tunneling oxide layer includes a molybdenum oxide layer and / or a nickel oxide layer;

[0015] The second tunneling oxide layer includes a silicon oxide layer.

[0016] Furthermore, in the above-mentioned double-sided TOPCon solar cell, the substrate is a phosphorus-doped silicon substrate, the first surface of the substrate is a light incident surface, and the second surface of the substrate is a backlight surface, and the double-sided TOPCon solar cell further includes:

[0017] The boron-doped emitter is located between the substrate and the first tunneling oxide layer.

[0018] Furthermore, in the above-mentioned double-sided TOPCon solar cell, the substrate is a boron-doped silicon substrate, the first surface of the substrate is a backlight surface, and the second surface of the substrate is a light incident surface, and the double-sided TOPCon solar cell further includes:

[0019] The phosphorus-doped emitter is located between the substrate and the second tunneling oxide layer.

[0020] Furthermore, in the above-mentioned double-sided TOPCon solar cell, the boron-doped polysilicon layer includes a heavily doped region and a lightly doped region located around the heavily doped region;

[0021] The orthographic projection of the heavily doped region on the substrate overlaps with the orthographic projection of the first gate on the substrate.

[0022] In a second aspect, the present invention provides a method for preparing a double-sided TOPCon solar cell, the method for preparing a double-sided TOPCon solar cell comprising:

[0023] forming a first tunnel oxide layer on the first surface of the substrate;

[0024] forming a boron-doped amorphous silicon layer on a side of the first tunnel oxide layer away from the substrate;

[0025] Annealing the boron-doped amorphous silicon layer to form a boron-doped polycrystalline silicon layer;

[0026] Forming a first aluminum oxide layer, a first silicon nitride layer and a first gate in sequence on a side of the boron-doped polysilicon layer away from the substrate;

[0027] forming a second tunnel oxide layer on the second surface of the substrate;

[0028] forming a phosphorus-doped amorphous silicon layer on a side of the second tunnel oxide layer away from the substrate;

[0029] sequentially forming a barrier pre-layer on a side of the phosphorus-doped polysilicon layer away from the substrate;

[0030] Annealing the phosphorus-doped amorphous silicon layer and the barrier pre-layer to form a phosphorus-doped polysilicon layer and a barrier layer; wherein the barrier layer is configured to provide positive charges;

[0031] A second aluminum oxide layer, a second silicon nitride layer and a second gate are sequentially formed on a side of the barrier layer away from the substrate.

[0032] Furthermore, in the above-mentioned method for preparing a double-sided TOPCon solar cell, before sequentially forming a barrier prefabricated layer on the side of the phosphorus-doped polysilicon layer away from the substrate, it also includes:

[0033] forming a transition pre-layer on a side of the phosphorus-doped polysilicon layer away from the substrate;

[0034] Annealing the phosphorus-doped amorphous silicon layer and the barrier prefabricated layer to form a phosphorus-doped polysilicon layer and a barrier layer, comprising:

[0035] The phosphorus-doped amorphous silicon layer, the transition pre-layer and the barrier pre-layer are annealed to form a phosphorus-doped polysilicon layer, a transition layer and a barrier layer.

[0036] The above one or more technical solutions of the present invention have at least one or more of the following beneficial effects:

[0037] When implementing the technical solution of the present invention, a second tunneling oxide layer, a phosphorus-doped polysilicon layer, a barrier layer, a second aluminum oxide layer, a second silicon nitride layer and a second gate are sequentially arranged on the second surface of the substrate and in a direction away from the second surface of the substrate, and the barrier layer provides positive charges, so that there are abundant positive charges between the phosphorus-doped polysilicon layer and the second aluminum oxide layer, and the negative charges of the phosphorus-doped polysilicon layer and the negative charges of the second aluminum oxide layer no longer repel each other, thereby avoiding carrier recombination, improving the passivation effect of the second aluminum oxide layer, and thereby improving the photoelectric conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The disclosure of the present invention will become more easily understood with reference to the accompanying drawings. It is easy for those skilled in the art to understand that these drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present invention. In addition, similar numbers in the drawings are used to represent similar components, wherein:

[0039] Figure 1is a schematic structural diagram of a double-sided TOPCon solar cell provided according to an embodiment of the present invention;

[0040] Figure 2 It is a schematic flow chart of an embodiment of a method for preparing a double-sided TOPCon solar cell of the present invention;

[0041] Figure 3 is a schematic structural diagram of another double-sided TOPCon solar cell provided according to an embodiment of the present invention. DETAILED DESCRIPTION

[0042] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0043] In the description of the present invention, the terms "first", "second", etc. are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first", "second", etc. may explicitly or implicitly include at least one of the features. In addition, in the present invention, unless otherwise clearly specified and defined, the terms "connected", "connected", etc. should be understood in a broad sense. For example, it can be directly connected or indirectly connected through an intermediate medium. It can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0044] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0045] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0046] The double-sided TOPcon cell has a double passivation structure, which makes the front side of the cell also have unidirectional carrier selectivity, reducing the recombination of carriers on the front side. The doped poly Si layer can reduce the contact resistance. At the same time, the double-sided TOPCon cell has the advantages of high bifaciality, low temperature rise coefficient and low attenuation rate, making the double-sided TOPCon cell junction the next generation mainstream cell.

[0047] However, it was observed that the passivation effect of this double-sided TOPCon cell was poor and the photoelectric conversion efficiency was low.

[0048] Based on this research, it was found that after the phosphorus-doped polysilicon layer is formed on one side of the double-sided TOPCon battery, an aluminum oxide layer is formed. Both the phosphorus-doped polysilicon layer and the aluminum oxide layer have negative charges, which repel each other and cause carrier recombination, resulting in passivation loss of the aluminum dioxide layer and low photoelectric conversion efficiency.

[0049] Therefore, in order to solve the above technical problems, the present invention provides the following technical solutions:

[0050] Figure 1 Schematic diagram of the structure of a double-sided TOPCon solar cell provided according to an embodiment of the present invention. Figure 1 As shown, the double-sided TOPCon solar cell includes a substrate. The substrate has a first surface and a second surface. One of the first surface of the substrate and the second surface of the substrate is a light incident surface, and the other is a backlight surface. The first surface and the second surface of different types of substrates are opposite. That is, if the substrate is a phosphorus-doped silicon substrate (denoted as an N-type substrate 101), the first surface of the substrate is the light incident surface, and the second surface of the substrate is the backlight surface. Conversely, if the substrate is a phosphorus boron silicon substrate (denoted as a P-type substrate 102), the first surface of the substrate is the backlight surface, and the second surface of the substrate is the light incident surface. Figure 1 The description is made by taking the N-type substrate 101 as an example.

[0051] In a specific implementation process, a first tunneling oxide layer 11, a boron-doped polysilicon layer 12, a first aluminum oxide layer 13, a first silicon nitride layer 14 and a first gate 15 are sequentially arranged on the first surface of the N-type substrate 101 and in a direction away from the first surface of the N-type substrate 101. A second tunneling oxide layer 16, a phosphorus-doped polysilicon layer 17, a barrier layer 18, a second aluminum oxide layer 19, a second silicon nitride layer 20 and a second gate 21 are sequentially arranged on the second surface of the N-type substrate 101 and in a direction away from the second surface of the N-type substrate 101; wherein the barrier layer 18 is configured to provide positive charges, so that due to the barrier of positive charges between the phosphorus-doped polysilicon layer 17 and the second aluminum oxide layer 19, the phosphorus-doped polysilicon layer 17 and the second aluminum oxide layer 19 are no longer repelled, carrier recombination is avoided, and the passivation loss of the second aluminum oxide layer 19 is avoided, thereby improving the photoelectric conversion efficiency of the double-sided TOPCon solar cell. The barrier layer 18 may be a polycrystalline silicon nitride layer, a silicon oxide layer, a silicon nitride layer, a silicon oxynitride layer, a molybdenum oxide layer, a nickel oxide layer, or the like.

[0052] In a specific implementation process, the first tunneling oxide layer 11 and the second tunneling oxide layer 16 have different material layers, so that different tunneling oxide layers can be used to select carriers in a directional manner to better improve battery efficiency. Specifically, the first tunneling oxide layer 11 includes a molybdenum oxide layer and / or a nickel oxide layer; the second tunneling oxide layer 16 includes a silicon oxide layer.

[0053] Continue to see Figure 1 Those skilled in the art can understand that, for the N-type substrate 101, a boron-doped emitter 22 is disposed between the N-type substrate 101 and the first tunneling oxide layer 11, and the boron-doped emitter 22 can be formed by boron diffusion.

[0054] In a specific implementation process, since the boron-doped polysilicon layer 12 added to the first surface of the substrate has more defects and produces more parasitic absorption, it is necessary to perform local heavy doping here to ensure current flow and metallization contact. In other words, the boron-doped polysilicon layer 12 includes a heavily doped region and a lightly doped region located around the heavily doped region; wherein the orthographic projection of the heavily doped region on the N-type substrate 101 overlaps with the orthographic projection of the first gate 15 on the N-type substrate 101.

[0055] Specifically, the boron-doped polysilicon layer 12 may be lightly doped first, and then the doping may be advanced by laser SE, so that the region corresponding to the first gate 15 forms a heavily doped region.

[0056] The double-sided TOPCon solar cell of this embodiment is provided with a second tunneling oxide layer 16, a phosphorus-doped polysilicon layer 17, a barrier layer 18, a second aluminum oxide layer 19, a second silicon nitride layer 20 and a second gate 21 in sequence on the second surface of the substrate and in the direction away from the second surface of the substrate, and the barrier layer 18 provides positive charge, so that there is abundant positive charge between the phosphorus-doped polysilicon layer 17 and the second aluminum oxide layer 19, and the negative charge of the phosphorus-doped polysilicon layer 17 and the negative charge of the second aluminum oxide layer 19 no longer repel each other, thereby avoiding carrier recombination, improving the passivation effect of the second aluminum oxide layer 19, and further improving the photoelectric conversion efficiency.

[0057] In a specific implementation process, although a barrier layer 18 is added between the phosphorus-doped polysilicon layer 17 and the second aluminum oxide layer 19 to prevent carrier recombination and avoid passivation loss of the second aluminum oxide layer 19, when the phosphorus-doped polysilicon layer 17 is in direct contact with the barrier layer 18, the grain boundary barrier at the contact surface between the two is high, which is not conducive to the transmission of carriers.

[0058] Therefore, in order to solve the above technical problems, the present invention also provides the following technical solutions.

[0059] Continue to see Figure 1 A transition layer 23 can be set between the phosphorus-doped polysilicon layer 17 and the barrier layer 18. The transition layer 23 can reduce the grain boundary barrier of the contact surface between the transition layer 23 and the phosphorus-doped polysilicon layer 17, and reduce the grain boundary barrier of the contact surface between the transition layer 23 and the barrier layer 18, so that the phosphorus-doped polysilicon layer 17 and the barrier layer 18 are more compatible and more conducive to the transmission of carriers.

[0060] Specifically, the transition layer 23 includes a phosphorus-doped polycrystalline silicon nitride layer; the barrier layer 18 includes a polycrystalline silicon nitride layer. In this way, the phosphorus-doped polycrystalline silicon nitride layer only adds nitrogen elements compared to the phosphorus-doped polycrystalline silicon layer 17. Because the difference between the two elements is small, the compatibility is better, and the grain boundary barrier between the contact surfaces of the two is relatively small. Similarly, the phosphorus-doped polycrystalline silicon nitride layer only reduces the phosphorus element compared to the polycrystalline silicon nitride layer. Because the difference between the two elements is small, the compatibility is better, and the grain boundary barrier between the contact surfaces of the two is relatively small.

[0061] Based on the above records, it can be known that the grain boundary barrier from the phosphorus-doped polysilicon layer 17 to the polycrystalline silicon nitride layer as a whole is smaller, has better compatibility, is more conducive to the transmission of carriers, and thus improves the photoelectric conversion efficiency. In addition, the phosphorus-doped polycrystalline silicon nitride layer can also inhibit blistering, inhibit crystallization, and thus optimize the passivation effect, and doping with nitrogen can show a better EQE response, the battery has a stronger light absorption ability, and then the short-circuit current will increase, and the photoelectric conversion efficiency will also increase accordingly.

[0062] In addition, the phosphorus-doped polycrystalline silicon nitride layer is selected as the transition layer 23, and the polycrystalline silicon nitride layer is used as the barrier layer 18. There is no need to improve the existing process equipment. It can be achieved by simply adding corresponding process steps after completing the phosphorus-doped polycrystalline silicon layer 17.

[0063] In a specific implementation process, Figure 2 FIG. 1 is a flow chart of an embodiment of a method for preparing a double-sided TOPCon solar cell according to the present invention. Figure 2 As shown, the preparation method may include the following steps:

[0064] S201, forming a first tunneling oxide layer 11 on a first surface of a substrate;

[0065] Specifically, a 130 mm N-type single crystal silicon wafer can be selected as a substrate, and a first tunneling oxide layer 11 with a thickness of about 1.5 nm is deposited on the first surface (light incident surface) of the N-type substrate by PECVD. The first tunneling oxide layer 11 may include a molybdenum oxide layer (the gas source is selected from oxygen, hydrogen and MoCl5) and / or a nickel oxide layer.

[0066] It should be noted that, before forming the first tunnel oxide layer 11 , the substrate may be textured to form an inverted pyramid structure, and then boron diffusion may be performed to form a boron-doped emitter.

[0067] S202, forming a boron-doped amorphous silicon layer on a side of the first tunnel oxide layer 11 away from the substrate;

[0068] A boron-doped amorphous silicon layer may be deposited on a side of the first tunnel oxide layer 11 away from the substrate using a gas source such as silane, hydrogen, and borane.

[0069] S203, annealing the boron-doped amorphous silicon layer to form a boron-doped polysilicon layer 12;

[0070] It should be noted that the boron-doped polysilicon layer 12 may be further treated with SE to push up doping at a local position (the position corresponding to the first gate 15 ) so that the position corresponding to the first gate 15 forms a heavily doped region and other positions are lightly doped regions.

[0071] S204, forming a first aluminum oxide layer 13, a first silicon nitride layer 14 and a first gate 15 in sequence on a side of the boron-doped polysilicon layer 12 away from the substrate;

[0072] A first aluminum oxide layer 13 of 4 to 5 nm can be deposited on the side of the boron-doped polysilicon layer 12 away from the substrate by tubular ALD (TMA and water are selected as the gas source); about 60 to 90 nm of silicon nitride is deposited on top of the first aluminum oxide layer 13 by PECVD (silane and ammonia are selected as the gas source); and finally, the first gate 15 is formed by screen printing.

[0073] S205, forming a second tunnel oxide layer 16 on the second surface of the substrate;

[0074] A tunneling oxide layer of silicon oxide (nitrous oxide or silane is selected as the gas source) with a thickness of about 1.5 nm can be deposited on the second surface (backlight surface) of the N-type substrate by PECVD as the second tunneling oxide layer 16 .

[0075] S206, forming a phosphorus-doped amorphous silicon layer on a side of the second tunneling oxide layer 16 away from the substrate;

[0076] A phosphorus-doped amorphous silicon layer with a thickness of 100-110 nm may be deposited on a side of the second tunnel oxide layer 16 away from the substrate using a gas source such as silane, hydrogen and phosphine.

[0077] S207, sequentially forming a barrier prefabricated layer on a side of the phosphorus-doped polysilicon layer 17 away from the substrate;

[0078] S208, annealing the phosphorus-doped amorphous silicon layer and the barrier prefabricated layer to form a phosphorus-doped polysilicon layer 17 and a barrier layer 18; wherein the barrier layer 18 is configured to provide positive charges;

[0079] S209 , forming a second aluminum oxide layer 19 , a second silicon nitride layer 20 , and a second gate 21 in sequence on a side of the barrier layer 18 away from the substrate.

[0080] It should be noted that the first aluminum oxide layer 13 and the second aluminum oxide layer 19 , the first silicon nitride layer 14 and the second silicon nitride layer 20 can be deposited on both sides simultaneously.

[0081] In a specific implementation process, before sequentially forming a barrier prefabricated layer on the side of the phosphorus-doped polysilicon layer 17 away from the substrate, the following steps may also be performed:

[0082] A transition pre-layer is formed on a side of the phosphorus-doped polysilicon layer 17 away from the substrate.

[0083] Correspondingly, the phosphorus-doped amorphous silicon layer, the transition pre-layer and the barrier pre-layer are annealed to form a phosphorus-doped polysilicon layer 17 , a transition layer 23 and a barrier layer 18 .

[0084] In a specific implementation process, the transition layer 23 includes a phosphorus-doped polycrystalline silicon nitride layer, and the gas source can be selected from silane, ammonia and phosphine; the barrier layer 18 includes a polycrystalline silicon nitride layer, and the gas source can be selected from silane and ammonia.

[0085] Figure 3 is a schematic diagram of the structure of another double-sided TOPCon solar cell provided according to an embodiment of the present invention. Figure 3 The P-type substrate is used as an example. Figure 2 As shown, and see Figure 1 It can be seen that the difference between the two is that the light incident surface and the backlight surface are opposite, and the film layers on each surface are also arranged oppositely. However, on the second surface (light incident surface) of the P-type substrate 102, a phosphorus-doped emitter 24 needs to be arranged between the P-type substrate 102 and the second tunneling oxide layer 16.

[0086] Therefore, for Figure 3 The bifacial TOPCon solar cell shown can be referenced Figure 1 The relevant records of the double-sided TOPCon solar cell shown are not repeated here.

[0087] In a specific implementation process, Figure 3 The preparation method of the double-sided TOPCon solar cell shown in FIG. Figure 1 The preparation methods of the bifacial TOPCon solar cells shown are basically the same, with the following differences:

[0088] Difference 1: The substrate is replaced with a 130mm P-type monocrystalline silicon wafer;

[0089] Difference 2: The first surface of the substrate serves as the backlight surface, and the second surface of the substrate serves as the light incident surface.

[0090] Difference 3: Before forming the second tunnel oxide layer 16 on the second surface of the P-type substrate 102, the P-type substrate 102 can be textured to form an inverted pyramid structure, and then phosphorus diffusion is performed to form a phosphorus-doped emitter. Before forming the first tunnel oxide layer 11, a boron-doped emitter will not be formed.

[0091] So far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. A double-sided tunnel passivation contact solar cell, characterized in that: include: substrate; A first tunneling oxide layer, a boron-doped polysilicon layer, a first aluminum oxide layer, a first silicon nitride layer and a first gate are sequentially arranged on the first surface of the substrate and in a direction away from the first surface of the substrate; A second tunneling oxide layer, a phosphorus-doped polysilicon layer, a barrier layer, a second aluminum oxide layer, a second silicon nitride layer and a second gate are sequentially arranged on the second surface of the substrate and in a direction away from the second surface of the substrate; wherein the barrier layer is configured to provide positive charge.

2. The double-sided tunnel passivated contact solar cell according to claim 1, characterized in that: Also includes: A transition layer is located between the phosphorus-doped polysilicon layer and the barrier layer.

3. The double-sided tunnel passivated contact solar cell according to claim 2, characterized in that: The transition layer includes a phosphorus-doped polycrystalline silicon nitride layer; The barrier layer includes a polycrystalline silicon nitride layer.

4. The double-sided tunnel passivated contact solar cell according to claim 1, characterized in that: The first tunnel oxide layer and the second tunnel oxide layer have different material layers.

5. The double-sided tunnel passivated contact solar cell according to claim 4, characterized in that: The first tunneling oxide layer includes a molybdenum oxide layer and / or a nickel oxide layer; The second tunneling oxide layer includes a silicon oxide layer.

6. The double-sided tunnel passivated contact solar cell according to claim 1, characterized in that: The substrate is a phosphorus-doped silicon substrate, the first surface of the substrate is a light-incident surface, the second surface of the substrate is a backlight surface, and the double-sided tunnel passivation contact solar cell further includes: The boron-doped emitter is located between the substrate and the first tunneling oxide layer.

7. The double-sided tunnel passivated contact solar cell according to claim 1, characterized in that: The substrate is a boron-doped silicon substrate, the first surface of the substrate is a backlight surface, the second surface of the substrate is a light incident surface, and the double-sided tunnel passivation contact solar cell further includes: The phosphorus-doped emitter is located between the substrate and the second tunneling oxide layer.

8. The double-sided tunnel passivated contact solar cell according to claim 1, characterized in that: The boron-doped polysilicon layer includes a heavily doped region and a lightly doped region located around the heavily doped region; The orthographic projection of the heavily doped region on the substrate overlaps with the orthographic projection of the first gate on the substrate.

9. A method for preparing a double-sided tunnel passivation contact solar cell, characterized in that: include: forming a first tunnel oxide layer on the first surface of the substrate; forming a boron-doped amorphous silicon layer on a side of the first tunnel oxide layer away from the substrate; Annealing the boron-doped amorphous silicon layer to form a boron-doped polycrystalline silicon layer; Forming a first aluminum oxide layer, a first silicon nitride layer and a first gate in sequence on a side of the boron-doped polysilicon layer away from the substrate; forming a second tunnel oxide layer on the second surface of the substrate; forming a phosphorus-doped amorphous silicon layer on a side of the second tunnel oxide layer away from the substrate; sequentially forming a barrier pre-layer on a side of the phosphorus-doped polysilicon layer away from the substrate; Annealing the phosphorus-doped amorphous silicon layer and the barrier pre-layer to form a phosphorus-doped polysilicon layer and a barrier layer; wherein the barrier layer is configured to provide positive charges; A second aluminum oxide layer, a second silicon nitride layer and a second gate are sequentially formed on a side of the barrier layer away from the substrate.

10. The method for preparing a double-sided tunnel passivation contact solar cell according to claim 9, characterized in that: Before sequentially forming a barrier prefabricated layer on a side of the phosphorus-doped polysilicon layer away from the substrate, the method further comprises: forming a transition pre-layer on a side of the phosphorus-doped polysilicon layer away from the substrate; Annealing the phosphorus-doped amorphous silicon layer and the barrier prefabricated layer to form a phosphorus-doped polysilicon layer and a barrier layer, comprising: The phosphorus-doped amorphous silicon layer, the transition pre-layer and the barrier pre-layer are annealed to form a phosphorus-doped polysilicon layer, a transition layer and a barrier layer.

Images