Intrinsic thin film heterojunction cell structure and applications

Abstract

This invention discloses an intrinsic thin-film heterojunction solar cell structure and its application, comprising: N-type monocrystalline silicon; a first intrinsic amorphous silicon thin film deposited on the upper surface of the N-type monocrystalline silicon; a doped N-type amorphous silicon thin film deposited on the upper surface of the first intrinsic amorphous silicon thin film; a first transparent conductive oxide thin film deposited on the upper surface of the doped N-type amorphous silicon thin film; a second intrinsic amorphous silicon thin film deposited on the lower surface of the N-type monocrystalline silicon; a doped P-type amorphous silicon thin film deposited on the lower surface of the second intrinsic amorphous silicon thin film; and a second transparent conductive oxide thin film deposited on the lower surface of the doped P-type amorphous silicon thin film. The purpose of this invention is to effectively reduce the series resistance of the heterojunction solar cell and enhance its anti-reflection effect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of batteries, and particularly relates to an intrinsic thin-film heterojunction battery structure and application. BACKGROUND

[0002] With the increasing demand for renewable energy worldwide, solar cell technology, as an effective means of directly converting solar energy into electricity, has received increasing attention in research and application. Among the many solar cell technologies, heterojunction batteries (HJT) have become one of the research hotspots in recent years due to their high photoelectric conversion efficiency and good stability. The design principle of heterojunction batteries is based on the construction of a light absorption zone on an N-type monocrystalline silicon substrate, which has high purity and good crystal structure, which helps to reduce the recombination loss of photo-generated carriers. By depositing silicon-based thin film stacks with different electrical properties on the front and back surfaces of the monocrystalline silicon substrate, a unique heterojunction structure is formed. This structure can effectively separate photo-generated electrons and holes, improving the photoelectric conversion efficiency of the battery. After forming the heterojunction structure, to further enhance the photoelectric performance of the battery, a layer or more of transparent conductive film is usually deposited on its surface, and a metal electrode is attached to the film to achieve current collection and export.

[0003] Heterojunction battery technology combines the mature experience of traditional crystalline silicon battery technology with advanced nanoscale coating technology in the semiconductor field, not only inheriting the high stability and long life advantages of crystalline silicon batteries, but also further improving the photoelectric conversion efficiency and controllability of production costs of the battery through nanoscale coating technology. However, despite the significant progress made in heterojunction battery technology, there are still some challenges. One key issue is the large series resistance problem that exists when heterojunction batteries collect current. The increase in series resistance directly leads to an increase in the internal resistance of the battery, which in turn reduces the fill factor and ultimately the photoelectric conversion efficiency of the battery. In addition, existing heterojunction batteries often overlook the improvement of the antireflection effect in their structural design, resulting in some of the incident light being reflected at the surface of the battery without being effectively absorbed and utilized, which has become a bottleneck limiting the further improvement of the performance of heterojunction batteries. SUMMARY

[0004] In view of the problems existing in the prior art, the present application provides an intrinsic thin-film heterojunction battery structure and application, which aims to effectively reduce the series resistance of the heterojunction battery and enhance its antireflection effect.

[0005] To solve the above technical problems, the present application is realized by the following technical scheme: According to a first aspect of the present application, an intrinsic thin-film heterojunction battery structure is provided, comprising: N-type monocrystalline silicon; The first intrinsic amorphous silicon thin film is deposited on the upper surface of the N-type monocrystalline silicon. A doped N-type amorphous silicon thin film is deposited on the upper surface of the first intrinsic amorphous silicon thin film; A first transparent conductive oxide film is deposited on the upper surface of the doped N-type amorphous silicon film; A second intrinsic amorphous silicon thin film is deposited on the lower surface of the N-type monocrystalline silicon. A doped P-type amorphous silicon thin film is deposited on the lower surface of the second intrinsic amorphous silicon thin film; A second transparent conductive oxide film is deposited on the lower surface of the doped P-type amorphous silicon film.

[0006] In one possible implementation of the first aspect, the thickness of the first intrinsic amorphous silicon thin film is 5 nm to 6 nm.

[0007] In one possible implementation of the first aspect, the thickness of the doped N-type amorphous silicon thin film is 5 nm to 7 nm.

[0008] In one possible implementation of the first aspect, the thickness of the second intrinsic amorphous silicon thin film is 6 nm to 8 nm.

[0009] In one possible implementation of the first aspect, the thickness of the doped p-type amorphous silicon thin film is 8 nm to 10 nm.

[0010] In one possible implementation of the first aspect, both the first transparent conductive oxide film and the second transparent conductive oxide film are made of indium tin oxide, aluminum zinc oxide, or fluorine-doped tin oxide.

[0011] One possible implementation of the first aspect also includes: A first metal-based electrode is deposited on the upper surface of the first transparent conductive oxide film.

[0012] One possible implementation of the first aspect also includes: A second metal-based electrode is deposited on the lower surface of the second transparent conductive oxide film.

[0013] In one possible implementation of the first aspect, both the first metal-based electrode and the second metal-based electrode are silver-based electrodes.

[0014] According to a second aspect of the present invention, an application of an intrinsic thin-film heterojunction battery structure is provided for use in a photovoltaic power generation system.

[0015] Compared with the prior art, the present invention has at least the following beneficial effects: This invention provides an intrinsic thin-film heterojunction solar cell structure. A thin-film stack structure is constructed on the front and back surfaces of an N-type single-crystal silicon substrate, and a transparent conductive oxide film (i.e., a first transparent conductive oxide film and a second transparent conductive oxide film) is deposited on the outermost layer of the stack. These transparent conductive oxide films possess excellent conductivity, effectively collecting and discharging current, thereby reducing the series resistance of the cell. Reduced series resistance means reduced internal resistance, which in turn improves the fill factor and ultimately the photoelectric conversion efficiency. The transparent conductive oxide film in this invention not only has conductivity but also reduces the reflection of incident light on the cell surface, allowing more light to enter the cell and be absorbed and utilized. Increased light absorption directly improves the photoelectric conversion efficiency, as more photons can excite photogenerated carriers, thus generating more current.

[0016] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the specific embodiments of the present invention, the drawings used in the description of the specific embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of an intrinsic thin-film heterojunction battery structure according to an embodiment of the present invention.

[0019] In the figure: 1-N-type monocrystalline silicon; 2-first intrinsic amorphous silicon thin film; 3-doped N-type amorphous silicon thin film; 4-first transparent conductive oxide thin film; 5-second intrinsic amorphous silicon thin film; 6-doped P-type amorphous silicon thin film; 7-second transparent conductive oxide thin film; 8-first metal-based electrode; 9-second metal-based electrode. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Combination Figure 1As shown, this embodiment of the invention provides an intrinsic thin-film heterojunction solar cell structure, which aims to effectively reduce series resistance and enhance anti-reflection effect through optimized structural design, thereby improving the photoelectric conversion efficiency and overall performance of the heterojunction solar cell. Specifically, the intrinsic thin-film heterojunction solar cell structure includes an N-type monocrystalline silicon 1, a first intrinsic amorphous silicon thin film 2, a doped N-type amorphous silicon thin film 3, a first transparent conductive oxide thin film 4, a second intrinsic amorphous silicon thin film 5, a doped P-type amorphous silicon thin film 6, and a second transparent conductive oxide thin film 7. The first intrinsic amorphous silicon thin film 2 is deposited on the upper surface of the N-type monocrystalline silicon 1; the doped N-type amorphous silicon thin film 3 is deposited on the upper surface of the first intrinsic amorphous silicon thin film 2; the first transparent conductive oxide thin film 4 is deposited on the upper surface of the doped N-type amorphous silicon thin film 3; the second intrinsic amorphous silicon thin film 5 is deposited on the lower surface of the N-type monocrystalline silicon 1; the doped P-type amorphous silicon thin film 6 is deposited on the lower surface of the second intrinsic amorphous silicon thin film 5; and the second transparent conductive oxide thin film 7 is deposited on the lower surface of the doped P-type amorphous silicon thin film 6.

[0022] More specifically, an N-type monocrystalline silicon wafer is selected as the substrate light absorption region of the solar cell, labeled N-type monocrystalline silicon 1. This silicon wafer should have high purity (typically requiring an impurity concentration below 10⁻³), a good crystal structure, and an appropriate thickness (typically between 100 μm and 200 μm) to ensure the photoelectric performance of the solar cell. The N-type monocrystalline silicon wafer is texturized to increase the surface roughness and improve light absorption efficiency. The texturing process typically involves etching the silicon wafer surface with an alkaline or acidic solution to form a pyramidal or inverted pyramidal microstructure. A thorough cleaning is then performed to remove impurities and contaminants from the silicon wafer surface, such as metal ions, organic matter, and inorganic salts, to ensure the quality of subsequent coatings. On the upper surface of the N-type monocrystalline silicon 1, a first intrinsic amorphous silicon thin film 2 is deposited using processes such as chemical vapor deposition (CVD) or physical vapor deposition (PVD). The first intrinsic amorphous silicon thin film 2 should have a uniform thickness and good electrical properties, serving as part of the front surface field and aiding in the separation of photogenerated electrons and holes. On the upper surface of the first intrinsic amorphous silicon thin film 2, a doped N-type amorphous silicon thin film 3 is deposited. The doped N-type amorphous silicon thin film 3, by incorporating appropriate amounts of impurity elements (such as phosphorus), forms N-type conductivity, creating an ohmic contact with the N-type single-crystal silicon substrate, which is beneficial for current collection. On the upper surface of the doped N-type amorphous silicon thin film 3, a first transparent conductive oxide thin film 4 is deposited. The first transparent conductive oxide thin film 4 should have high transmittance and low resistivity, which not only reduces the series resistance during current collection but also acts as an anti-reflection agent, improving the light absorption efficiency of the battery.

[0023] On the lower surface of the N-type monocrystalline silicon 1, a second intrinsic amorphous silicon thin film 5 is deposited using processes such as chemical vapor deposition or physical vapor deposition. The second intrinsic amorphous silicon thin film 5 serves a similar function to the first intrinsic amorphous silicon thin film 2, but is located on the back side of the silicon wafer. On the lower surface of the second intrinsic amorphous silicon thin film 5, a doped P-type amorphous silicon thin film 6 is deposited. The doped P-type amorphous silicon thin film 6, by incorporating appropriate amounts of impurity elements (such as boron), forms P-type conductivity and creates a PN heterojunction with the N-type monocrystalline silicon substrate, which is a key component in generating the photovoltage of the solar cell. On the lower surface of the doped P-type amorphous silicon thin film 6, a second transparent conductive oxide thin film 7 is deposited. The second transparent conductive oxide thin film 7 also has high transmittance and low resistivity, which helps reduce the series resistance of the back-side current and acts as an anti-reflection agent.

[0024] Through the above specific implementation steps, the present invention constructs an intrinsic thin-film heterojunction battery structure. This structure not only has high photoelectric conversion efficiency, but also effectively reduces series resistance and enhances anti-reflection effect by optimizing the coating process and structural design, which is conducive to the development and application of heterojunction battery technology.

[0025] In one possible implementation, the thickness of the first intrinsic amorphous silicon thin film 2 is 5 nm to 6 nm. Specifically, by controlling process parameters such as deposition time and gas flow rate, the first intrinsic amorphous silicon thin film 2 is ensured to have uniform thickness and good electrical properties. A first intrinsic amorphous silicon thin film 2 with a thickness of 5 nm to 6 nm helps reduce recombination losses of photogenerated carriers in the film, improves the photoelectric conversion efficiency of the battery, and simultaneously ensures the stability of the film. For example, the thickness of the first intrinsic amorphous silicon thin film 2 is 5 nm.

[0026] In one possible implementation, the thickness of the doped N-type amorphous silicon thin film 3 is 5 nm to 7 nm. This thickness range of 5 nm to 7 nm facilitates the formation of better ohmic contacts and reduces contact resistance. For example, the thickness of the doped N-type amorphous silicon thin film 3 is 5 nm.

[0027] In one possible implementation, the thickness of the second intrinsic amorphous silicon thin film 5 is 6 nm to 8 nm. Similarly, a second intrinsic amorphous silicon thin film 5 is deposited on the lower surface of the N-type single-crystal silicon 1 using processes such as chemical vapor deposition or physical vapor deposition. The thickness of this film is in the range of 6 nm to 8 nm. Similar to the first intrinsic amorphous silicon thin film 2, the thickness of the second intrinsic amorphous silicon thin film 5 is beneficial for optimizing the transport of photogenerated carriers and reducing recombination losses. Simultaneously, the second intrinsic amorphous silicon thin film 5 also serves as part of the PN heterojunction, forming the heterojunction structure of the battery together with the subsequent doped P-type amorphous silicon thin film 6. For example, the thickness of the second intrinsic amorphous silicon thin film 5 is 6 nm.

[0028] In one possible implementation, the thickness of the doped p-type amorphous silicon thin film 6 is 8 nm to 10 nm. This thickness range of 8 nm to 10 nm ensures that the doped p-type amorphous silicon thin film 6 facilitates the formation of a better PN heterojunction interface, thereby improving the photoelectric conversion efficiency of the battery. For example, the thickness of the doped p-type amorphous silicon thin film 6 is 8 nm.

[0029] Preferably, the first transparent conductive oxide film 4 and the second transparent conductive oxide film 7 are both made of indium tin oxide, zinc aluminum oxide, or fluorine-doped tin oxide. Specifically, the materials selected for the first transparent conductive oxide film 4 and the second transparent conductive oxide film 7 are indium tin oxide, zinc aluminum oxide, or fluorine-doped tin oxide. These materials have high light transmittance (greater than 80%), low resistivity, and good chemical stability, which can effectively reduce the series resistance during current collection and play an anti-reflection role, thereby improving the light absorption efficiency of the battery. For example, the thickness of the first transparent conductive oxide film 4 and the second transparent conductive oxide film 7 is 100 nm.

[0030] In one implementation, an intrinsic thin-film heterojunction battery structure further includes a first metal-based electrode 8, which is deposited on the upper surface of a first transparent conductive oxide thin film 4. That is, a first metal-based electrode 8 is deposited on the upper surface of the first transparent conductive oxide thin film 4. Exemplarily, the electrode is made of a metal with high conductivity and good stability, such as silver, copper, aluminum, or nickel. The introduction of the first metal-based electrode 8 can further reduce the series resistance of the battery, improve the current collection efficiency, and enhance the stability of the battery.

[0031] In one possible implementation, an intrinsic thin-film heterojunction battery structure further includes a second metal-based electrode 9, which is deposited on the lower surface of the second transparent conductive oxide thin film 7. The material and design of the second metal-based electrode 9 are similar to those of the first metal-based electrode 8. The introduction of the second metal-based electrode 9 can further enhance the current harvesting capability of the battery and improve the short-circuit current and photoelectric conversion efficiency.

[0032] Preferably, both the first metal-based electrode 8 and the second metal-based electrode 9 are silver-based electrodes. Silver-based electrodes can efficiently conduct current while maintaining structural stability, thereby optimizing the battery's conductivity and structural stability.

[0033] In another embodiment, the present invention provides an application of an intrinsic thin-film heterojunction solar cell structure in a photovoltaic power generation system. That is, the structure is applied to a photovoltaic power generation system. Intrinsic thin-film heterojunction solar cells, as a novel photovoltaic cell technology, are considered a breakthrough direction for the photovoltaic industry due to their high power generation, low cost per kilowatt-hour, and high photoelectric conversion efficiency. In this embodiment, the intrinsic thin-film heterojunction solar cell employs a special thin-film structure and heterojunction technology to achieve highly efficient photoelectric conversion, with a photoelectric conversion efficiency exceeding 24%, and potentially further increasing to over 30%. This high photoelectric conversion capability enables photovoltaic power generation systems to utilize solar energy resources more effectively, improving energy output efficiency.

[0034] For example, photovoltaic power generation systems with intrinsic thin-film heterojunction cell structures can be widely used in various applications requiring solar power generation, such as: for residential and commercial electricity use, providing a stable power supply to residential and commercial buildings to meet the electricity needs of daily life and work; for industrial electricity use, providing power support to factories, workshops and other industrial sites, reducing production costs and improving production efficiency; for public utilities electricity use, providing power to public facilities such as streetlights and traffic lights, ensuring the normal operation of urban infrastructure; and for power supply in remote areas, building photovoltaic power generation systems in remote areas or areas with insufficient power supply to provide power support to local residents and improve their living conditions.

[0035] In summary, the application of the intrinsic thin-film heterojunction battery structure of this invention in photovoltaic power generation systems has the characteristics of high photoelectric conversion efficiency, low cost per kilowatt-hour, good stability and reliability, as well as environmental protection and sustainability. This enables photovoltaic power generation systems to better meet various electricity demands and promote the development of clean energy.

[0036] In the description of this invention, it should be understood that the terms "upper", "lower", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0037] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0038] In this invention, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0039] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0040] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0041] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. An intrinsic thin-film heterojunction battery structure, characterized in that, include: N-type monocrystalline silicon (1); A first intrinsic amorphous silicon thin film (2) is deposited on the upper surface of the N-type monocrystalline silicon (1); A doped N-type amorphous silicon thin film (3) is deposited on the upper surface of the first intrinsic amorphous silicon thin film (2); A first transparent conductive oxide film (4) is deposited on the upper surface of the doped N-type amorphous silicon film (3); A second intrinsic amorphous silicon thin film (5) is deposited on the lower surface of the N-type monocrystalline silicon (1); A doped P-type amorphous silicon thin film (6) is deposited on the lower surface of the second intrinsic amorphous silicon thin film (5); A second transparent conductive oxide film (7) is deposited on the lower surface of the doped P-type amorphous silicon film (6).

2. The intrinsic thin-film heterojunction battery structure according to claim 1, characterized in that, The thickness of the first intrinsic amorphous silicon thin film (2) is 5 nm to 6 nm.

3. The intrinsic thin-film heterojunction battery structure according to claim 1, characterized in that, The thickness of the doped N-type amorphous silicon thin film (3) is 5 nm to 7 nm.

4. The intrinsic thin-film heterojunction battery structure according to claim 1, characterized in that, The thickness of the second intrinsic amorphous silicon thin film (5) is 6 nm to 8 nm.

5. The intrinsic thin-film heterojunction battery structure according to claim 1, characterized in that, The thickness of the doped P-type amorphous silicon thin film (6) is 8 nm to 10 nm.

6. The intrinsic thin-film heterojunction battery structure according to claim 1, characterized in that, The first transparent conductive oxide film (4) and the second transparent conductive oxide film (7) are both made of any one of indium tin oxide, zinc aluminum oxide or fluorine-doped tin oxide.

7. The intrinsic thin-film heterojunction battery structure according to claim 1, characterized in that, Also includes: A first metal-based electrode (8) is deposited on the upper surface of the first transparent conductive oxide film (4).

8. The intrinsic thin-film heterojunction battery structure according to claim 7, characterized in that, Also includes: The second metal-based electrode (9) is deposited on the lower surface of the second transparent conductive oxide film (7).

9. The intrinsic thin-film heterojunction battery structure according to claim 8, characterized in that, Both the first metal-based electrode (8) and the second metal-based electrode (9) are silver-based electrodes.

10. The application of the intrinsic thin-film heterojunction battery structure according to any one of claims 1 to 9, characterized in that, It is used in photovoltaic power generation systems.

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