N-type BC battery back emitter structure

Abstract

The utility model discloses a back emitter structure of an N-type BC battery, which relates to the field of emitter structures and comprises a P-type emitter mechanism arranged on a silicon substrate and sequentially comprising a passivation layer, a P-Poly layer and a first tunneling oxide layer; the N-type emitter mechanism is arranged on the silicon substrate and sequentially comprises a tunneling layer and an N-Poly layer; the emitter slotting mechanism is arranged between the P-type emitter mechanism and the N-type emitter mechanism, and an emitter slot is arranged to prevent electrons of the N-type emitter mechanism from directly flowing into the P-type emitter mechanism; and the silicon nitride mask layer mechanism is used for isolating the P-Poly layer from the N-Poly layer. According to the utility model, the P-type emitter mechanism, the N-type emitter mechanism and the emitter slotting mechanism are arranged, and the mask layer mechanism is made of a silicon nitride material, so that the purposes of improving the passivation effect and the energy conversion efficiency of the BC battery are achieved.

Description

Technical Field

[0001] The utility model relates to the field of emitter structures, in particular to a back emitter structure of an N-type BC battery. Background Art

[0002] In the era of green and sustainable development, solar photovoltaic technology has the potential to meet humanity's demand for electricity, reduce dependence on non-renewable energy, and thus address natural environmental changes such as global warming, rising sea levels, and extreme climates. Currently, improving the efficiency of photovoltaic cells faces significant challenges, as many factors limit their photoelectric conversion efficiency. For example, the front grid lines of the cell block light, significantly limiting the front light-receiving area. BC cells eliminate the front grid lines and concentrate the cell's P and N emitters on the back, thereby increasing the cell's light-receiving area and significantly improving the cell's short-circuit current density, resulting in a significant efficiency improvement.

[0003] However, the emitter structure of existing BC batteries has limitations, and the passivation performance and energy conversion efficiency are relatively low.

[0004] In view of this, this application is hereby filed. Utility Model Content

[0005] The purpose of the present utility model is to provide an N-type BC battery back emitter structure, by setting a P-type emitter structure and an N-type emitter structure, the structure of the emitter slot structure, and selecting a mask layer structure made of silicon nitride material to solve the problem of poor passivation effect of BC batteries in the prior art.

[0006] The present invention is implemented through the following technical solutions: The present invention provides an N-type BC battery back emitter structure, including:

[0007] A P-type emitter structure is provided on a silicon substrate and sequentially comprises a passivation layer, a P-Poly layer, and a first tunneling oxide layer;

[0008] An N-type emitter structure is provided on a silicon substrate and includes a tunneling layer and an N-Poly layer in sequence;

[0009] An emitter slot mechanism is provided between the P-type emitter mechanism and the N-type emitter mechanism, wherein the emitter slot is provided to prevent electrons of the N-type emitter mechanism from directly flowing into the P-type emitter mechanism;

[0010] The silicon nitride mask layer structure is used to isolate the P-Poly layer and the N-Poly layer.

[0011] Preferably, in the P-type emitter structure, an N-Poly layer is further provided outside the first tunneling oxide layer, the silicon nitride mask layer structure includes a first mask layer, and a first mask layer is provided outside the N-Poly layer. The emitter groove structure can isolate the N-Poly layer of the N-type emitter structure from the N-Poly layer outside the first tunneling oxide layer.

[0012] Preferably, the passivation layer is an aluminum oxide layer, and the thickness of the aluminum oxide layer is 7-12 nm.

[0013] Preferably, the thickness of the P-Poly layer is 100-130 nm.

[0014] Preferably, the tunneling layer includes a second tunneling oxide layer and a conductive film, and the thickness of the tunneling layer is 1.2 nm to 1.8 nm.

[0015] Preferably, the conductive film includes at least one of indium tin oxide, aluminum-doped oxide and indium zinc oxide, and the conductive film is a transparent film.

[0016] Preferably, in the N-type emitter structure, the thickness of the N-Poly layer is 90-140 nm.

[0017] Preferably, in the N-type emitter structure, a first mask layer is provided outside the N-Poly layer, and the thickness of the first mask layer outside the N-Poly layer is 70-100 nm;

[0018] The emitter trenching mechanism can isolate the first mask layer outside the N-type emitter mechanism from the first mask layer outside the P-type emitter mechanism.

[0019] Preferably, the silicon nitride mask layer structure includes a second mask layer, which is arranged on the inner side of the emitter slot structure. In the radial direction of the emitter slot structure, the inner side of the second mask layer is a P-Poly layer. The emitter slot structure includes a slot, and the width of the slot is 0.1~0.2µm.

[0020] Preferably, the notch is open on the outside and extends along the inside to the range of the second mask layer, and the thickness of the second mask layer is 120-160 nm.

[0021] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0022] 1. The back emitter structure of the N-type BC battery provided by the embodiment of the present invention sets the P-type emitter structure on the silicon substrate, and the P-Poly layer forms a pn junction with the silicon substrate, which effectively shunts the carriers and improves the photoelectric conversion efficiency of the battery. The passivation layer reduces the recombination of carriers on the surface and improves the open circuit voltage of the battery. The N-Poly layer serves as the electron collection area, and the tunneling layer allows electrons to pass through the N-Poly layer through the tunneling effect, reducing the recombination of electrons on the surface. The first tunneling oxide layer allows majority carriers (electrons) to pass through the next layer of P-Poly layer through the quantum tunneling effect, while minority carriers (holes) are blocked, thereby realizing selective carrier collection, which helps to improve the photoelectric conversion efficiency of the battery because it reduces the carrier recombination on the battery surface, thereby increasing the open circuit voltage.

[0023] The emitter slot is located between the P-type and N-type emitter structures, preventing electrons from the N-type emitter from flowing directly into the P-type emitter, thus preventing leakage. The silicon nitride mask layer prevents direct contact between the P-type and N-type regions, reducing leakage. In this embodiment of the utility model, the silicon nitride layer provides excellent chemical stability and passivation, reducing carrier recombination on the surface. This structure effectively enhances the directional migration of carriers, thereby improving the efficiency of the battery. By optimizing the structure and layout of the back emitter, the photoelectric conversion efficiency of the battery is significantly improved while maintaining the aesthetic appearance of the battery.

[0024] 2. In the embodiment of the present invention, the passivation layer of the P-type emitter structure adopts an aluminum oxide layer, that is, an Al2O3 layer is introduced between the P-Poly layer and the silicon substrate. x O y The Al layer acts as a passivation layer, providing additional passivation effect and reducing the recombination of carriers at the interface between the P-type emitter and the silicon substrate. x O y The layer has high chemical stability and good field effect passivation ability, which can effectively block the contact between minority carriers (holes) and the surface, reduce their recombination losses, and further improve the photoelectric conversion efficiency of the battery.

[0025] 3. The N-type emitter structure of the embodiment of the present invention uses a tunneling layer including a second tunneling oxide layer and a conductive film, that is, in the N-type emitter region, a structure of a tunneling oxide layer and a conductive film is used. The tunneling oxide layer allows majority carriers (electrons) to pass through the conductive film through the tunneling effect, while minority carriers (holes) are blocked, thereby enhancing the effect of directional carrier migration, realizing selective carrier collection, providing a good passivation effect, reducing contact resistance, and further improving the electron collection efficiency.

[0026] In general, the back emitter structure of the N-type BC battery provided by the embodiment of the present invention is achieved by setting a P-type emitter structure and an N-type emitter structure, and the structure of the emitter groove structure, and selecting silicon nitride material for the mask layer structure to achieve the purpose of improving the passivation effect and energy conversion efficiency of the BC battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 A schematic diagram of the back emitter structure of an N-type BC battery provided in an embodiment of the present utility model;

[0029] Figure 2 An enlarged schematic diagram of a P-type emitter structure A provided in an embodiment of the present invention;

[0030] Figure 3 An enlarged schematic diagram of the N-type emitter structure B provided in an embodiment of the present invention;

[0031] Figure 4 This is an enlarged schematic diagram of the emitter slotting mechanism structure C provided in an embodiment of the present utility model.

[0032] Markings and corresponding parts names in the accompanying drawings:

[0033] 1-silicon substrate, 2-passivation layer, 3-P-Poly layer, 4-first tunneling oxide layer, 5-tunneling layer, 6-N-Poly layer, 7-first mask layer, 8-second mask layer, 9-notch. DETAILED DESCRIPTION

[0034] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0035] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are also within the scope of protection of the present invention.

[0036] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0037] In the description of the present invention, it should be noted that the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0038] Example

[0039] like Figure 1 As shown, the embodiment of the present invention provides an N-type BC battery back emitter structure, including: a P-type emitter structure, which is arranged on a silicon substrate 1 and includes a passivation layer 2, a P-Poly layer 3, and a first tunneling oxide layer 4 from top to bottom; the P-Poly layer 3 acts as a P-type emitter, forms a pn junction with the silicon substrate 1, promotes the separation and collection of photogenerated carriers, the passivation layer 2 reduces the recombination of carriers on the surface, and the first tunneling oxide layer 4 allows electrons to tunnel to the P-Poly layer 3, while blocking holes and reducing recombination losses; an N-type emitter structure, which is arranged on a silicon substrate 1 and includes a tunneling layer 5 and an N-Poly layer 6 from top to bottom; the N-Poly layer 6 acts as an N-type emitter, collects photogenerated electrons, and tunnels Layer 5 allows electrons to tunnel to the N-Poly layer 6, improving electron collection efficiency. The emitter slot mechanism is located between the P-type emitter mechanism and the N-type emitter mechanism. The emitter slot is configured to prevent electrons from the N-type emitter mechanism from directly flowing into the P-type emitter mechanism, preventing leakage, ensuring the electrical independence of the P-type and N-type regions, optimizing the battery's current output, improving the battery's current output and voltage performance, and reducing carrier recombination losses on the back surface. The silicon nitride mask layer mechanism is used to isolate the P-Poly layer 3 and the N-Poly layer 6, preventing direct contact between the P-type and N-type regions and reducing leakage. The silicon nitride layer provides excellent chemical stability and passivation, reducing carrier recombination on the surface. This solves the problem of insufficient isolation between the P-type and N-type regions in BC batteries in the prior art, resulting in limited battery efficiency. The back-emitter structure of the N-type BC battery provided by the present invention significantly improves the battery's photoelectric conversion efficiency by optimizing the structure and layout of the back-emitter, while maintaining the battery's aesthetic appearance.

[0040] Furthermore, if Figure 2 As shown, in the P-type emitter structure, an N-Poly layer 6 is further disposed outside the first tunneling oxide layer 4, the silicon nitride mask layer structure includes a first mask layer 7, and the first mask layer 7 is disposed outside the N-Poly layer 6. The emitter groove structure can isolate the N-Poly layer 6 of the N-type emitter structure from the N-Poly layer 6 outside the first oxide layer. Specifically, because the P-Poly layer 3 is generally deposited first and then the N-Poly layer 6 during the processing of this structure, there is a layer of N-Poly layer 6 outside the P-Poly layer 3 that is isolated by the silicon nitride mask layer structure. The function of the first mask layer 7 is to protect the N-Poly layer 6 and prevent damage to the N-Poly layer 6 in subsequent process steps. At the same time, the emitter groove structure can isolate the N-Poly layer 6 of the N-type emitter structure from the N-Poly layer 6 outside the first tunneling oxide layer 4, which helps to reduce current loss within the battery and improve the efficiency and performance of the battery.

[0041] As a preferred embodiment of the present invention, the passivation layer 2 is an aluminum oxide layer, and the thickness of the aluminum oxide layer is 7 to 12 nm. The aluminum oxide layer is negatively charged and can repel some electrons, making it difficult for electrons to pass from the silicon substrate 1 through the P emitter. Specifically, the aluminum oxide layer contains a large amount of fixed negative charge density, which can provide a good field effect passivation effect, helping to reduce the minority carrier density on the surface of the silicon substrate 1, thereby reducing the surface recombination rate and increasing the open circuit voltage of the battery. Since the passivation effect of the aluminum oxide layer mainly comes from its high density of fixed negative charges, these charges can provide strong field effect passivation. When the aluminum oxide layer is too thin, it cannot provide enough charge to achieve effective field effect passivation, resulting in a decrease in the open circuit voltage of the battery. On the contrary, if the aluminum oxide layer is too thick, it will cause the internal resistance of the battery to increase, affecting the fill factor and short-circuit current of the battery, thereby reducing the overall efficiency of the battery. Therefore, the thickness of the aluminum oxide layer is better in the range of 7 to 12 nm. More preferably, the thickness of the P-Poly layer 3 is 100~130nm, because the appropriate thickness of the P-Poly layer 3 can find the best balance between optical loss and electrical performance. A too thick P-Poly layer 3 will lead to increased photon absorption, thereby reducing the short-circuit current density; while a too thin P-Poly layer 3 cannot provide sufficient doping concentration and passivation effect, affecting the battery efficiency.

[0042] It should be noted that the aluminum oxide layer here includes trivalent aluminum, but is not limited to trivalent aluminum. The aluminum oxide layer can be a mixture of aluminum oxides of different valences, which is not limited here. Similarly, silicon nitride includes Si3N4, but is not limited to Si3N4, and can be a mixture of silicon nitrides of different valences, which is not limited here.

[0043] Furthermore, if Figure 3As shown, the tunneling layer 5 includes a second tunneling oxide layer and a conductive film, and the thickness of the tunneling layer 5 is 1.2nm~1.8nm. Specifically, the tunneling layer 5 is located on the silicon substrate 1. The second tunneling oxide layer can provide high-quality chemical passivation on the silicon surface to passivate the surface defects of the crystalline silicon substrate due to its low bond density and few defect states. The conductive film has good lateral conductivity, low optical absorption coefficient and good thermal stability. Exemplarily, the conductive film can be a mixture of one or more of indium tin oxide, aluminum-doped oxide and indium zinc oxide. The conductive film is preferably a transparent film, which can reduce optical loss and reduce parasitic absorption while ensuring high electrical performance of the tunneling oxide layer. Setting the thickness of the tunneling layer 5 to 1.2nm~1.8nm can ensure that electrons can effectively tunnel into the polysilicon layer while blocking the transport of holes and reducing the recombination current.

[0044] As a preferred embodiment of the present invention, in the N-type emitter structure, the thickness of the N-Poly layer 6 is 90-140 nm. This thickness range helps provide sufficient doping concentration while maintaining low recombination losses. More preferably, in the N-type emitter structure, a first mask layer 7 is provided outside the N-Poly layer 6, and the thickness of the first mask layer 7 outside the N-Poly layer 6 is 70-100 nm. The emitter groove mechanism can isolate the first mask layer 7 outside the N-type emitter structure from the first mask layer 7 outside the P-type emitter structure. Specifically, the first mask layer 7 is used to protect the N-Poly layer 6 and ensure the passivation performance of the N-Poly layer 6. At the same time, it cannot be too thick to avoid excessive metallization temperature. The emitter groove mechanism can isolate the first mask layer 7 outside the N-type emitter structure from the first mask layer 7 outside the P-type emitter structure, thereby effectively separating the P-type and N-type emitters.

[0045] Furthermore, if Figure 4As shown, the silicon nitride mask layer structure includes a second mask layer 8, which is disposed inside the emitter slot structure. In the radial direction of the emitter slot structure, the inner side of the second mask layer 8 is the P-Poly layer 3. The emitter slot structure includes a notch 9 with a width of 0.1-0.2µm. Preferably, the notch 9 is open on the outside and extends along the inside into the second mask layer 8. The thickness of the second mask layer 8 is 120-160nm. Specifically, the width of the notch 9 is precisely controlled during the laser slotting process to ensure effective separation between the P-type and N-type emitters while minimizing damage to the N-Poly layer 6, ensuring efficient carrier collection and transport, and reducing current loss within the battery. The thickness of the second mask layer 8 is 70-100nm, which helps provide good passivation while maintaining appropriate laser transmittance to facilitate subsequent laser slotting processes. In the laser grooving process, the grooving depth needs to be strictly controlled. If the N-Poly layer 6 needs to be completely removed, it is critical to set the thickness of the second mask layer 8 to be in the range of 120~160nm. This ensures sufficient thickness to achieve laser grooving to separate the P and N emitters without damaging the P-Poly layer 3.

[0046] In general, the embodiment of the present invention significantly improves the photoelectric conversion efficiency of the battery by optimizing the structure and layout of the back emitter while maintaining the aesthetic appearance of the battery. This structure can effectively increase the short-circuit current density and open-circuit voltage of the battery, thereby improving the overall conversion efficiency of the battery. By using silicon nitride (Si x N y )Mask layer, Al x O y The structure of the passivation layer 2 and the tunneling oxide layer plus the conductive film further improves the passivation performance of the battery and the directional migration efficiency of carriers, making the battery more efficient.

[0047] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, improvements, and the like made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention. It should be noted that the structures and components illustrated in the accompanying drawings are not necessarily drawn to scale, and that descriptions of known components, processing techniques, and processes are omitted to avoid unnecessarily limiting the present invention.

Claims

1. An N-type BC battery back emitter structure, characterized in that: include: A P-type emitter structure is provided on a silicon substrate (1) and sequentially comprises a passivation layer (2), a P-Poly layer (3), and a first tunneling oxide layer (4); An N-type emitter structure is provided on a silicon substrate (1) and sequentially comprises a tunneling layer (5) and an N-Poly layer (6); an emitter slot mechanism, disposed between the P-type emitter mechanism and the N-type emitter mechanism, wherein the emitter slot is configured to prevent electrons of the N-type emitter mechanism from directly flowing into the P-type emitter mechanism; A silicon nitride mask layer structure is used to isolate the P-Poly layer (3) and the N-Poly layer (6).

2. The back emitter structure of an N-type BC battery according to claim 1, characterized in that: In a P-type emitter structure, an N-Poly layer (6) is further provided outside the first tunneling oxide layer (4), the silicon nitride mask layer structure includes a first mask layer (7), a first mask layer (7) is provided outside the N-Poly layer (6), and the emitter slotting structure is capable of isolating the N-Poly layer (6) of the N-type emitter structure from the N-Poly layer (6) outside the first tunneling oxide layer (4).

3. The back emitter structure of an N-type BC battery according to claim 2, characterized in that: The passivation layer (2) is an aluminum oxide layer, and the thickness of the aluminum oxide layer is 7-12 nm.

4. The back emitter structure of an N-type BC battery according to claim 3, characterized in that: The thickness of the P-Poly layer (3) is 100-130 nm.

5. The back emitter structure of an N-type BC battery according to claim 2, characterized in that: The tunneling layer (5) comprises a second tunneling oxide layer and a conductive film, and the thickness of the tunneling layer (5) is 1.2 nm to 1.8 nm.

6. The back emitter structure of an N-type BC battery according to claim 5, characterized in that: The conductive film includes at least one of indium tin oxide, aluminum-doped oxide and indium zinc oxide, and the conductive film is a transparent film.

7. The back emitter structure of an N-type BC battery according to claim 6, characterized in that: In the N-type emitter structure, the thickness of the N-Poly layer (6) is 90-140 nm.

8. The back emitter structure of an N-type BC battery according to claim 7, characterized in that: In the N-type emitter structure, a first mask layer (7) is provided outside the N-Poly layer (6), and the thickness of the first mask layer (7) outside the N-Poly layer (6) is 70-100 nm; The emitter slotting mechanism is capable of isolating the first mask layer (7) outside the N-type emitter mechanism from the first mask layer (7) outside the P-type emitter mechanism.

9. The back emitter structure of an N-type BC battery according to claim 2, characterized in that: The silicon nitride mask layer structure includes a second mask layer (8), the second mask layer (8) is arranged on the inner side of the emitter slot structure, and in the radial direction of the emitter slot structure, the inner side of the second mask layer (8) is a P-Poly layer (3), and the emitter slot structure includes a slot (9), and the width of the slot (9) is 0.1-0.2µm.

10. The back emitter structure of an N-type BC battery according to claim 9, characterized in that: The notch (9) is open on the outside and extends along the inside to within the range of the second mask layer (8), and the thickness of the second mask layer (8) is 120-160 nm.

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