Solar cell and photovoltaic module

Abstract

The utility model discloses a solar cell and a photovoltaic module, and relates to the field of photovoltaic technology. The solar cell comprises a first transparent conductive layer, an n-type microcrystalline silicon layer, a first intrinsic amorphous silicon layer, an n-type monocrystalline silicon layer, a second intrinsic amorphous silicon layer, a p-type microcrystalline silicon layer and a second transparent conductive layer which are sequentially stacked, and the first transparent conductive layer and the second transparent conductive layer are connected with a first electrode and a second electrode respectively. Wherein a first passivation layer is further arranged between the n-type monocrystalline silicon layer and the p-type microcrystalline silicon layer, and the first passivation layer is made of zinc-doped aluminum oxide. In the embodiment of the utility model, the first passivation layer formed by zinc-doped aluminum oxide is arranged on one side of the back surface of the n-type monocrystalline silicon layer, so that dangling bonds and defects at an interface can be reduced, carrier recombination on the surface of the silicon layer is effectively reduced, and filling factors and the conversion efficiency of the solar cell are improved. Therefore, the solar cell provided by the embodiment of the invention has the characteristic of high photoelectric conversion efficiency.

Description

Technical Field

[0001] The present application relates to the field of photovoltaic technology, and in particular to a solar cell and a photovoltaic module. Background Art

[0002] Heterojunction cells are suitable for a variety of solar applications, including residential, commercial and industrial solar systems, due to their high efficiency and stability. As costs decrease and efficiency increases, heterojunction cells are expected to occupy a larger share of the future photovoltaic market, especially in applications that pursue high efficiency and long-term performance reliability. The core of heterojunction cells is that they use at least two different semiconductor materials to form a junction, rather than a junction formed within a single material. Taking silicon heterojunction (SHJ) cells as an example, one or more layers of amorphous silicon or microcrystalline silicon films are deposited on a single crystal silicon substrate to create a heterojunction structure. Silicon heterojunction cells are a high-efficiency solar cell technology that combines the stability of single crystal silicon with the high efficiency characteristics of amorphous silicon thin films. The core advantage of silicon heterojunction cells lies in their unique structure and manufacturing process, which makes them excel in conversion efficiency, temperature coefficient and long-term stability.

[0003] However, the photoelectric conversion efficiency of silicon heterojunction cells in related technologies still has room for improvement. Utility Model Content

[0004] The purpose of the present application is to provide a solar cell and a photovoltaic module, which have a high photoelectric conversion efficiency.

[0005] The embodiment of the present application is implemented as follows:

[0006] In a first aspect, the present application provides a solar cell, comprising a first transparent conductive layer, an n-type microcrystalline silicon layer, a first intrinsic amorphous silicon layer, an n-type single crystal silicon layer, a second intrinsic amorphous silicon layer, a p-type microcrystalline silicon layer and a second transparent conductive layer stacked in sequence, wherein the first transparent conductive layer and the second transparent conductive layer are respectively connected to a first electrode and a second electrode;

[0007] A first passivation layer is arranged between the n-type single crystal silicon layer and the p-type microcrystalline silicon layer, and the first passivation layer is zinc-doped aluminum oxide.

[0008] In an optional embodiment, the first passivation layer is disposed between the n-type single crystal silicon layer and the second intrinsic amorphous silicon layer.

[0009] In an optional embodiment, the first passivation layer is disposed between the second intrinsic amorphous silicon layer and the p-type microcrystalline silicon layer.

[0010] In an optional embodiment, the thickness of the first passivation layer is 5-8 nm.

[0011] In an optional embodiment, the area of ​​the first transparent conductive layer not covered with the first electrode is also covered with a second passivation layer, the second passivation layer.

[0012] In an optional embodiment, the second passivation layer is aluminum oxide or zinc-doped aluminum oxide.

[0013] In an optional embodiment, the thickness of the first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer are both 3-15 nm.

[0014] In an optional embodiment, the thickness of the n-type microcrystalline silicon layer is 10-40 nm, and the thickness of the p-type microcrystalline silicon layer is 15-45 nm.

[0015] In an optional embodiment, the thickness of the first transparent conductive layer is less than the thickness of the second transparent conductive layer.

[0016] In an optional embodiment, the thickness of the first transparent conductive layer is 70-120 nm, and the thickness of the second transparent conductive layer is 80-140 nm.

[0017] In an optional embodiment, the first transparent conductive layer includes a nitrogen-doped zinc oxide layer, an indium tin oxide layer and a titanium oxide layer stacked in sequence, the nitrogen-doped zinc oxide layer is connected to the first electrode, and the titanium oxide layer is connected to the n-type microcrystalline silicon layer.

[0018] In a second aspect, the present application provides a photovoltaic assembly, comprising the solar cell of any one of the aforementioned embodiments.

[0019] The beneficial effects of the embodiments of the present application are:

[0020] The present application provides a solar cell, comprising a first transparent conductive layer, an n-type microcrystalline silicon layer, a first intrinsic amorphous silicon layer, an n-type single crystal silicon layer, a second intrinsic amorphous silicon layer, a p-type microcrystalline silicon layer and a second transparent conductive layer stacked in sequence, wherein the first transparent conductive layer and the second transparent conductive layer are connected to a first electrode and a second electrode respectively. Among them, a first passivation layer is also arranged between the n-type single crystal silicon layer and the p-type microcrystalline silicon layer, and the first passivation layer is zinc-doped aluminum oxide. In an embodiment of the present application, by arranging a first passivation layer composed of zinc-doped aluminum oxide on the back side of the n-type single crystal silicon layer (i.e., the side facing the p-type microcrystalline silicon layer), dangling bonds and defects at the interface can be reduced, carrier recombination on the surface of the silicon layer can be effectively reduced, and the open circuit voltage of the battery can be increased, thereby increasing the minority carrier lifetime of the silicon layer and the conversion efficiency of the solar cell. The aluminum oxide of the first passivation layer reduces the non-ideal path of the current through passivation, thereby helping to improve the fill factor. The first passivation layer can also help reduce surface reflection, increase light absorption, and thus increase the short circuit current (Isc) of the battery. By doping aluminum oxide with zinc, defect energy levels can be formed in the aluminum oxide. These energy levels are located between the conduction band and the valence band, increasing the concentration of holes and making the first passivation layer have the characteristics of a P-type semiconductor. In addition, the oxygen functional groups of aluminum oxide can also form oxidation bonds with zinc atoms, increase the oxygen vacancy density, and improve the carrier mobility, thereby improving the photoelectric conversion efficiency. Therefore, the solar cell provided in the embodiment of the present application has the characteristics of high photoelectric conversion efficiency.

[0021] The photovoltaic module provided in the embodiment of the present application includes the above-mentioned solar cell, and therefore also has the above-mentioned corresponding beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 This is a schematic diagram of the structure of a solar cell in the first embodiment of the present application;

[0024] Figure 2 This is a schematic diagram of the structure of a solar cell in the second embodiment of the present application;

[0025] Figure 3 This is a schematic diagram of the structure of a solar cell in the third embodiment of the present application;

[0026] Figure 4 This is a schematic diagram of the structure of a solar cell in the fourth embodiment of the present application;

[0027] Figure 5 The present invention is a flowchart of a method for manufacturing a solar cell in one embodiment of the present invention.

[0028] Icon: 100-n-type single crystal silicon layer; 110-first intrinsic amorphous silicon layer; 120-second intrinsic amorphous silicon layer; 200-n-type microcrystalline silicon layer; 300-first transparent conductive layer; 310-nitrogen-doped zinc oxide layer; 320-indium tin oxide layer; 330-titanium oxide layer; 340-second passivation layer; 400-first electrode; 500-p-type microcrystalline silicon layer; 600-second transparent conductive layer; 700-second electrode; 800-first passivation layer. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0030] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0031] 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, further definition and explanation thereof is not required in subsequent drawings.

[0032] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the utility model product is usually placed when in use. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0033] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0034] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0035] Silicon heterojunction solar cells have the advantages of high conversion efficiency, low temperature coefficient, double-sided power generation, thin film, simple process, etc., which makes them have broad application prospects in photovoltaic power stations, rooftop solar energy systems, building integrated photovoltaics (BIPV), etc. It is often composed of a single crystal silicon substrate and an amorphous silicon film formed on both sides. At the interface between crystalline silicon and amorphous silicon, a special heterojunction is formed. This structure helps to optimize the efficiency of light absorption and carrier (electron and hole) separation. At the heterojunction interface, a thin layer of intrinsic amorphous silicon is usually inserted to passivate the surface of the battery, thereby reducing surface recombination and improving the conversion efficiency of the battery. At the heterojunction interface, due to the difference in band structure, electrons and holes are separated, electrons move to the n-type region, and holes move to the p-type region. The separated electrons and holes are collected on both sides of the battery, forming a potential difference. When the external circuit is closed, electrons flow from the n-type side of the battery to the p-type side through the external circuit, thereby forming a current.

[0036] In solar cells, the fill factor (FF) is an important parameter of the output performance of solar cells. It reflects the ratio of the maximum power output of the battery under actual working conditions to the maximum theoretical power output under ideal conditions. The fill factor FF is specifically expressed as: FF = maximum power of the solar cell / (open circuit voltage × short circuit current). The fill factor ranges from 0 to 1. The higher the fill factor, the better the performance of the battery and the higher the energy conversion efficiency. An ideal solar cell should have the highest possible fill factor, which means that the battery can be closer to its theoretical maximum power output under actual working conditions. The fill factor is affected by many factors, including the material quality of the battery, the manufacturing process, the battery design, the lighting conditions and the temperature. In the battery design and manufacturing process, optimizing the fill factor is a key task to improve the overall efficiency and performance of solar cells.

[0037] In silicon heterojunction cells, there is a problem of interfacial recombination. Interfacial recombination refers to the non-radiative recombination of carriers (electrons and holes) that occurs at the interface of different semiconductor materials. When two different materials form a heterojunction, there may be defects or mismatched band structures at the interface between them, which can provide a channel for electrons and holes to recombine. Recombination can occur even in the absence of photogenerated carriers, thereby reducing the number of available carriers. Therefore, interfacial recombination will lead to a decrease in the number of photogenerated carriers, thereby reducing the short-circuit current (Isc) and open-circuit voltage (Voc) of the battery, and ultimately leading to a decrease in the photoelectric conversion efficiency of the battery. At the same time, a high interfacial recombination rate will increase the series resistance of the battery, resulting in a decrease in the fill factor (FF), which affects the maximum power output of the battery.

[0038] The photoelectric conversion efficiency and fill factor of silicon heterojunction cells in the related art still have a large room for improvement. To this end, the embodiment of the present application provides a solar cell, which improves its photoelectric conversion efficiency by providing zinc-doped aluminum oxide as a passivation layer.

[0039] Figure 1 Schematic diagram of the structure of a solar cell in the first embodiment of the present application. Figure 1 As shown, the solar cell provided in the embodiment of the present application is specifically a silicon heterojunction cell, which includes a first transparent conductive layer 300, an n-type microcrystalline silicon layer 200, a first intrinsic amorphous silicon layer 110, an n-type single crystal silicon layer 100, a second intrinsic amorphous silicon layer 120, a p-type microcrystalline silicon layer 500 and a second transparent conductive layer 600 stacked in sequence, and the first transparent conductive layer 300 and the second transparent conductive layer 600 are respectively connected to a first electrode 400 and a second electrode 700.

[0040] Among them, the n-type single crystal silicon layer 100 not only serves as the basis for the generation of photogenerated carriers in the heterojunction cell, but also provides key support for the cell's high efficiency, high stability and good thermal performance through its excellent physical and chemical properties. As the main light-absorbing layer of the heterojunction cell, the n-type single crystal silicon layer 100 has a high purity and long-life minority carrier, which enables it to effectively absorb sunlight and generate electron-hole pairs. N-type silicon has a lower iron impurity content, which helps to reduce the density of recombination centers, thereby improving carrier lifetime and cell efficiency. The longer minority carrier lifetime of n-type silicon means that electrons and holes have more time to reach the electrode without being recombined, so the open circuit voltage and overall efficiency of the cell can be increased. The surface of the n-type single crystal silicon layer 100 can be passivated by depositing intrinsic amorphous silicon (ia-Si), such as the first intrinsic amorphous silicon layer 110 and the second intrinsic amorphous silicon layer 120 in the embodiment of the present application, thereby reducing surface recombination and further improving efficiency. Hydrogen atoms in amorphous silicon can passivate dangling bonds and reduce surface defects, thereby improving battery performance.

[0041] The temperature coefficient of n-type silicon is low, which means that the efficiency decreases less in high temperature environments, maintaining a higher energy output. Due to the high quality of the n-type single crystal silicon layer 100, the heterojunction cell can be designed as a double-sided cell, which can absorb light from both the front and back sides, thereby increasing the overall power output. The heterojunction structure formed by the n-type single crystal silicon layer 100 and other materials such as amorphous silicon or microcrystalline silicon has good compatibility, and this structure helps to improve the stability and durability of the cell.

[0042] In the embodiment of the present application, the first intrinsic amorphous silicon layer 110 and the second intrinsic amorphous silicon layer 120 are hydrogenated amorphous silicon, which can effectively passivate the dangling bonds on the surface of crystalline silicon and reduce the surface recombination centers, thereby improving the life of carriers and the open circuit voltage (Voc) of the battery. This is due to the presence of hydrogen atoms in the intrinsic amorphous silicon layer, which can terminate the dangling bonds of silicon atoms, reduce defects, and improve the transmission efficiency of charge carriers. The interface between the intrinsic amorphous silicon layer and the n-type single crystal silicon layer 100 forms a heterojunction, that is, an interface between different semiconductor materials. This heterojunction is conducive to improving the separation efficiency of photogenerated carriers, because the difference in energy band structure can promote the effective separation of electrons and holes. The intrinsic amorphous silicon layer has a certain anti-reflection effect, which can reduce the reflection of light at the interface, thereby increasing the amount of light entering the n-type single crystal silicon layer 100 and improving the light absorption efficiency. The intrinsic amorphous silicon layer also helps to improve the long-term stability and durability of the battery and reduce performance degradation; it also makes the heterojunction battery compatible with low-temperature processes, which is of great significance for improving production efficiency and reducing costs.

[0043] In the embodiment of the present application, the n-type microcrystalline silicon layer 200 is hydrogenated microcrystalline silicon (which can be expressed as μc-Si:H), and the grain size of microcrystalline silicon is smaller than the grains in polycrystalline silicon, but larger than the disordered region in amorphous silicon. Microcrystalline silicon generally has a wide spectral absorption range, can absorb short-wavelength light, supplement the insufficient absorption of single crystal silicon in certain wavelength ranges, and improve the total light absorption efficiency of the battery. In this embodiment, one of the main functions of the n-type microcrystalline silicon layer 200 is to serve as an electron injection layer. When sunlight irradiates the battery, the photogenerated electrons are pushed to the n-type microcrystalline silicon layer 200 under the action of the electric field of the pn junction, and then collected to the electrode through the layer (specifically, they are sequentially transported to the first electrode 400 through the n-type microcrystalline silicon layer 200 and the first transparent conductive layer 300). The n-type microcrystalline silicon layer 200 can be made using a low-temperature deposition process, which helps to reduce the thermal stress on the n-type single crystal silicon layer 100 and the first intrinsic amorphous silicon layer 110, avoid the degradation of material properties that may be caused by high-temperature processes, and also reduce production costs.

[0044] In this embodiment, the p-type microcrystalline silicon layer 500 is hydrogenated microcrystalline silicon. The p-type microcrystalline silicon layer 500 participates in the formation of the pn junction. When photons are absorbed and electron-hole pairs are generated, the built-in electric field of the pn junction will cause the electrons and holes to move in opposite directions and gather in the n-type and p-type regions, respectively, thereby generating current. Similar to the n-type microcrystalline silicon layer 200, due to the wide spectrum absorption characteristics of microcrystalline silicon, the p-type microcrystalline silicon layer 500 can enhance the absorption of short-wavelength light, supplement the insufficient absorption of n-type single crystal silicon in certain spectral ranges, and improve the overall light absorption efficiency of the battery. In addition, the p-type microcrystalline silicon layer 500 has the effect of selectively transmitting carriers. The p-type microcrystalline silicon layer 500 acts as an electron blocking layer, mainly allowing holes to pass through, while preventing the reverse flow of electrons, which helps to improve the fill factor of the battery. In addition, the deposition of the p-type microcrystalline silicon layer 500 can also be completed at a relatively low temperature, which reduces the thermal stress on the n-type single crystal silicon layer 100 and the second intrinsic amorphous silicon layer 120 and is beneficial to maintaining the crystal quality and electrical properties of the base material.

[0045] The materials of the first transparent conductive layer 300 and the second transparent conductive layer 600 are both transparent conductive oxides (Transparent Conductive Oxide, TCO). The transparent conductive layers have good conductivity and high transparency. This allows them to not block the incident sunlight, ensuring that the light can fully irradiate the interior of the battery, thereby generating photocurrent. The transparent conductive layer can collect the current generated by the photogenerated carriers (electrons and holes) and guide it to the external circuit through the electrodes, thereby achieving the output of electricity.

[0046] In the embodiment of the present application, a first passivation layer 800 is further disposed between the n-type single crystal silicon layer 100 and the p-type microcrystalline silicon layer 500. The first passivation layer 800 is zinc-doped aluminum oxide (Zn-AlO x ). Figure 1 In the embodiment, the first passivation layer 800 is disposed between the second intrinsic amorphous silicon layer 120 and the p-type microcrystalline silicon layer 500 .

[0047] The main functions of aluminum oxide in the first passivation layer 800 are field passivation and hydrogen passivation. Field passivation is to improve the surface quality of semiconductors by using electric field effects. Aluminum oxide can provide fixed or variable charges, change the potential near the semiconductor surface, thereby affecting the position of the surface energy level and reducing the harmful effects of surface dangling bonds. Field passivation can significantly reduce the interface recombination rate, increase the minority carrier lifetime, and thus improve the performance of solar cells. The principle of hydrogen passivation is that the aluminum oxide deposition process is composed of Al(OH) x The first passivation layer 800 is a semiconductor layer that is formed by a phase transition, and therefore is rich in a large flow of H. H diffuses to the near surface of the silicon wafer and into the matrix, and hydrogen atoms can form covalent bonds with the dangling bonds on the semiconductor surface, thereby stabilizing the surface state and reducing surface recombination centers. This method is particularly suitable for silicon-based semiconductors because the silicon-hydrogen bond is very stable and can significantly improve the electrical properties of the material. In short, the passivation effect of the first passivation layer 800 can reduce interface recombination and improve the performance of solar cells.

[0048] The aluminum oxide in the first passivation layer 800 can also serve as an electron selective contact layer, allowing electrons to pass through while limiting the transmission of holes, which helps to improve the fill factor (FF) and short circuit current (Isc) of the battery. It can be understood that when the fill factor is constant, the greater the short circuit current or open circuit voltage, the greater the maximum output power of the solar cell; and when the short circuit current and open circuit voltage are constant, the greater the fill factor, the greater the maximum output power of the solar cell. Therefore, the first passivation layer 800 significantly improves the performance of the solar cell.

[0049] Furthermore, the first passivation layer 800 with appropriate thickness and refractive index can help reduce surface reflection and improve light absorption, thereby increasing the short-circuit current of the solar cell.

[0050] In addition, the first passivation layer 800 can be prepared at low temperature by processes such as atomic layer deposition (ALD), which reduces thermal stress on the silicon substrate and helps to maintain the integrity of the battery material, so the manufacturing difficulty and production cost are relatively low.

[0051] In the embodiment of the present application, the aluminum oxide of the first passivation layer 800 is doped with zinc. Zn can be doped in AlO xDefective energy levels are formed in the film, which are located between the conduction band and the valence band, increasing the concentration of holes and making the film layer have the characteristics of a P-type semiconductor. In addition, the oxygen functional groups of aluminum oxide can also form oxidized bonds with zinc atoms, increasing the oxygen vacancy density and improving the carrier mobility, thereby improving the photoelectric conversion efficiency of solar cells. In addition, the introduction of zinc will also improve the chemical stability of aluminum oxide and extend the service life of the device.

[0052] Figure 2 Schematic diagram of the structure of the solar cell in the second embodiment of the present application. Figure 2 As shown, the first passivation layer 800 is disposed between the second intrinsic amorphous silicon layer 120 and the p-type microcrystalline silicon layer 500 (as shown in FIG. Figure 1 ), it can also be disposed between the n-type single crystal silicon layer 100 and the second intrinsic amorphous silicon layer 120 (such as Figure 2 When the first passivation layer 800 is disposed between the n-type single crystal silicon layer 100 and the second intrinsic amorphous silicon layer 120 , its function and effect are similar to those when it is disposed between the second intrinsic amorphous silicon layer 120 and the p-type microcrystalline silicon layer 500 , and will not be described in detail herein.

[0053] In the embodiment of the present application, the thickness of the n-type single crystal silicon layer 100 is 80 to 180 μm; the thickness of the first intrinsic amorphous silicon layer 110 and the second intrinsic amorphous silicon layer 120 are both 3 to 15 nm; the thickness of the n-type microcrystalline silicon layer 200 is 10 to 40 nm, and the thickness of the p-type microcrystalline silicon layer 500 is 15 to 45 nm.

[0054] The materials of the first transparent conductive layer 300 and the second transparent conductive layer 600 are both transparent conductive oxides (Transparent Conductive Oxide, TCO). The transparent conductive layer has good conductivity and high transparency. This makes them not block the incident sunlight, ensuring that the light can fully irradiate the interior of the battery, thereby generating photocurrent. The transparent conductive layer can collect the current generated by the photogenerated carriers (electrons and holes) and guide it to the external circuit through electrodes, thereby realizing the output of electricity. Furthermore, the thickness of the first transparent conductive layer 300 is greater than the thickness of the second transparent conductive layer 600. Since the first transparent conductive layer 300 is usually used as the front of the solar cell and the second transparent conductive layer 600 is used as the back of the solar cell, the thinner first transparent conductive layer 300 can improve the light transmittance, reduce the shielding of the incident sunlight, ensure that more light can directly irradiate the solar cell, and improve the light absorption rate. In addition, in order to reduce surface reflection, other layer structures (such as Figure 3The second passivation layer 340 in the embodiment plays a protective role, so the first transparent conductive layer 300 should not be too thick and does not need to be too thick. The light entering the battery through the second transparent conductive layer 600 is relatively small, so the priority of light transmittance is relatively low. A relatively thick second transparent conductive layer 600 helps to form a more stable contact, reduce contact resistance, and thus improve the overall efficiency of the solar cell.

[0055] In an optional embodiment, the thickness of the first transparent conductive layer 300 is 70-120 nm, and the thickness of the second transparent conductive layer 600 is 80-140 nm.

[0056] Figure 3 Schematic diagram of the structure of the solar cell in the third embodiment of the present application. Figure 3 As shown, in Figure 1 Based on the embodiment, the solar cell may further include a second passivation layer 340, which covers the area on the first transparent conductive layer 300 that is not covered by the first electrode 400. Due to its stability, the second passivation layer 340 provides a certain degree of physical and chemical protection for the solar cell, prevents the degradation of the solar cell material in a harsh environment, and improves the long-term stability and reliability of the battery. In addition, the second passivation layer 340 can reduce surface reflection, improve light absorption, and thus improve the short-circuit current of the battery.

[0057] In the embodiment of the present application, the material of the second passivation layer 340 is aluminum oxide or zinc-doped aluminum oxide. The aluminum oxide film has the characteristic of fixed negative charge, which can reduce the work function of the first transparent conductive layer 300, play a field passivation effect, improve carrier mobility, and improve battery efficiency.

[0058] In this embodiment, the thickness of the second passivation layer 340 is 1-10 nm, for example, 5 nm.

[0059] Figure 4 Schematic diagram of the structure of the solar cell in the fourth embodiment of the present application. Figure 4 As shown, the first transparent conductive layer 300 of the solar cell provided in the embodiment of the present application may include a nitrogen-doped zinc oxide layer 310, an indium tin oxide layer 320 and a titanium oxide layer 330 which are stacked in sequence, the nitrogen-doped zinc oxide layer 310 is connected to the first electrode 400, and the titanium oxide layer 330 is connected to the n-type microcrystalline silicon layer 200.

[0060] Zinc oxide is a direct bandgap semiconductor, and its bandgap width is about 3.37eV at room temperature. The optical properties of zinc oxide are closely related to the bandgap width. Only when the photons with energy greater than its optical bandgap irradiate the zinc oxide film, the electrons in the film will absorb the photons and transition from the valence band to the conduction band, resulting in strong light absorption. Therefore, the ZnO film only absorbs ultraviolet light with a wavelength below 368nm, and has a high transmittance to light with a wavelength greater than 368nm, that is, it has a very high transmittance in the visible light range, so that as much visible light as possible can enter the interior of the heterojunction battery, thereby improving the power generation efficiency. In addition, under ultraviolet light irradiation, the transmittance of the ZnO film in the visible light range does not change substantially, indicating that the ZnO film has excellent radiation resistance. In addition, since the nitrogen-doped zinc oxide layer 310 can absorb ultraviolet light of shorter wavelengths and reduce the ultraviolet light entering the battery, it can reduce the power attenuation (Ultraviolet InducedDegradation, UVID) of the battery due to ultraviolet light.

[0061] In the nitrogen-doped zinc oxide layer 310 , nitrogen atoms replace oxygen atoms in the zinc oxide lattice to form donor energy levels and release free electrons, thereby increasing the n-type conductivity of the material, thereby enabling the first transparent conductive layer 300 to have good electrical and optical properties.

[0062] The titanium oxide layer 330 has the characteristics of simple preparation, wide bandgap and low cost. It is a semiconductor material with a large bandgap. 2 The band gap is about 3.2 eV, and has a high carrier mobility. The titanium oxide layer 330 has good chemical stability and weather resistance, and can be used as a protective layer or a reinforcement layer to improve the overall performance and life of the first transparent conductive layer 300.

[0063] Furthermore, the titanium oxide layer 330 may be nitrogen-doped titanium oxide, fluorine-doped titanium oxide or carbon-doped titanium oxide. By doping with nitrogen (N), fluorine (F), carbon (C) and the like, its conductivity may be significantly improved.

[0064] Indium tin oxide (ITO) has good electrical conductivity, which is due to the fact that the doping of tin provides additional free electrons, so that indium tin oxide can be used as a conductive layer to collect and transmit photogenerated carriers. Indium tin oxide has high transparency in the visible spectrum range, allowing visible light to enter the interior of the battery. Indium tin oxide can also provide a surface passivation effect and improve the photoelectric conversion efficiency of the device. In addition, indium tin oxide can also reduce the contact resistance between the metal electrode and the semiconductor material, which helps to smoothly transmit the current. Therefore, the indium tin oxide layer 320 in the first transparent conductive layer 300 ensures the optical and electrical properties of the first transparent conductive layer 300. Since the material cost of the indium tin oxide layer 320 is higher than that of the titanium oxide layer 330 and the nitrogen-doped zinc oxide layer 310, in this embodiment, only the middle layer of the first transparent conductive layer 300 is made of indium tin oxide, which can reduce the amount of indium tin oxide used and reduce the material cost of the first transparent conductive layer 300.

[0065] In this embodiment, the thickness of the indium tin oxide layer 320 is not greater than the thickness of the nitrogen-doped zinc oxide layer 310, and is greater than the thickness of the titanium oxide layer 330. Since the indium tin oxide layer 320 is not easy to be too thick or too thin, too large a thickness will result in higher costs, while too low a thickness may affect the performance of the first transparent conductive layer 300. If the thickness ratio of the titanium oxide layer 330 is too large, the conductive performance of the first transparent conductive layer 300 may be affected, so the thickness of the controller needs to be less than the thickness of the indium tin oxide layer 320.

[0066] In the embodiment of the present application, the coverage area of ​​the first electrode 400 accounts for 1% to 5% of the area of ​​the first transparent conductive layer 300. By controlling the coverage area of ​​the first electrode 400 to be within a relatively low range, as much light as possible can be allowed to enter the heterojunction battery. Similarly, the coverage area of ​​the second electrode 700 can also be controlled, for example, the coverage area of ​​the second electrode 700 accounts for 1% to 5% of the area of ​​the second transparent conductive layer 600.

[0067] Figure 5 Flow chart of a method for manufacturing a solar cell in one embodiment of the present application. The manufacturing method can be used to manufacture the solar cell provided in the embodiment of the present application. Figure 5 As shown, the production method includes:

[0068] Step S100 , obtaining an n-type single crystal silicon layer 100 , and cleaning and texturing the n-type single crystal silicon layer 100 .

[0069] Through the texturing process, a textured surface can be formed on the surface of the n-type single crystal silicon layer 100 to be combined with the first intrinsic amorphous silicon layer 110 and the second intrinsic amorphous silicon layer 120 .

[0070] In step S200 , a first intrinsic amorphous silicon layer 110 and an n-type microcrystalline silicon layer 200 are deposited on one side of the n-type single crystal silicon layer 100 , and a second intrinsic amorphous silicon layer 120 , a first passivation layer 800 and a p-type microcrystalline silicon layer 500 are deposited on the other side.

[0071] In a specific embodiment, the second intrinsic amorphous silicon layer 120 and the first passivation layer 800 are sequentially deposited, and then the first intrinsic amorphous silicon layer 110 is deposited; then the n-type microcrystalline silicon layer 200 is deposited on the first intrinsic amorphous silicon layer 110, and then the p-type microcrystalline silicon layer 500 is deposited on the first passivation layer 800. The method is suitable for preparing Figure 1 In other embodiments, the above steps may be adaptively adjusted, for example, the first passivation layer 800 may be deposited first, and then the second intrinsic amorphous silicon layer 120 may be deposited. This method is suitable for preparing Figure 2 A solar cell of an embodiment.

[0072] In step S300 , a first transparent conductive layer 300 is deposited on the n-type microcrystalline silicon layer 200 , and a second transparent conductive layer 600 is deposited on the p-type microcrystalline silicon layer 500 .

[0073] In this embodiment, the first transparent conductive layer 300 and the second transparent conductive layer 600 can be deposited by atomic layer deposition (ALD), chemical vapor deposition (CVD) or physical vapor deposition (PVD). The specific principle can refer to the existing related technology and will not be repeated here.

[0074] In step S400 , a first electrode 400 and a second electrode 700 are formed on the first transparent conductive layer 300 and the second transparent conductive layer 600 , respectively.

[0075] In this embodiment, the first electrode 400 and the second electrode 700 with specific patterns may be formed by screen printing technology or electroplating technology.

[0076] Optionally, to make Figure 3 In the case of the solar cell in the embodiment, the manufacturing method may further include depositing a second passivation layer 340. Specifically, before manufacturing the first electrode 400, the second passivation layer 340 may be first deposited on the first transparent conductive layer 300; then, a specific area of ​​the second passivation layer 340 may be etched using an etching process to expose the first transparent conductive layer 300 in the specific area; and finally, the first electrode 400 may be manufactured on the exposed first transparent conductive layer 300, so that the first electrode 400 is connected to the first transparent conductive layer 300.

[0077] In summary, the present application provides a solar cell, comprising a first transparent conductive layer 300, an n-type microcrystalline silicon layer 200, a first intrinsic amorphous silicon layer 110, an n-type single crystal silicon layer 100, a second intrinsic amorphous silicon layer 120, a p-type microcrystalline silicon layer 500 and a second transparent conductive layer 600, which are stacked in sequence, and the first transparent conductive layer 300 and the second transparent conductive layer 600 are respectively connected to a first electrode 400 and a second electrode 700. Among them, a first passivation layer 800 is also arranged between the n-type single crystal silicon layer 100 and the p-type microcrystalline silicon layer 500, and the first passivation layer 800 is zinc-doped aluminum oxide. In the embodiment of the present application, by arranging a first passivation layer 800 composed of zinc-doped aluminum oxide on the back side of the n-type single crystal silicon layer 100 (i.e., the side facing the p-type microcrystalline silicon layer 500), the dangling bonds and defects at the interface can be reduced, the carrier recombination on the surface of the silicon layer can be effectively reduced, and the open circuit voltage of the battery can be increased, thereby improving the minority carrier lifetime of the silicon layer and the conversion efficiency of the solar cell. The aluminum oxide of the first passivation layer 800 reduces the non-ideal path of the current through passivation, thereby helping to improve the fill factor. The first passivation layer 800 can also help reduce surface reflections and improve light absorption, thereby increasing the short-circuit current (Isc) of the battery. By doping zinc in aluminum oxide, defect energy levels can be formed in the aluminum oxide, which are located between the conduction band and the valence band, increasing the concentration of holes and giving the first passivation layer 800 the characteristics of a P-type semiconductor. In addition, the oxygen functional groups of aluminum oxide can also form oxidized bonds with zinc atoms, increase the oxygen vacancy density, and improve carrier mobility, thereby improving the photoelectric conversion efficiency. Therefore, the solar cell provided in the embodiment of the present application has the characteristics of high photoelectric conversion efficiency.

[0078] The photovoltaic module provided in the embodiment of the present application includes the above-mentioned solar cell, and therefore also has the above-mentioned corresponding beneficial effects.

[0079] The above are only preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A solar cell, characterized in that: The invention comprises a first transparent conductive layer, an n-type microcrystalline silicon layer, a first intrinsic amorphous silicon layer, an n-type single crystal silicon layer, a second intrinsic amorphous silicon layer, a p-type microcrystalline silicon layer and a second transparent conductive layer which are stacked in sequence, wherein the first transparent conductive layer and the second transparent conductive layer are connected to a first electrode and a second electrode respectively; Wherein, a first passivation layer is further arranged between the n-type single crystal silicon layer and the p-type microcrystalline silicon layer, and the first passivation layer is zinc-doped aluminum oxide.

2. The solar cell according to claim 1, characterized in that: The first passivation layer is disposed between the n-type single crystal silicon layer and the second intrinsic amorphous silicon layer.

3. The solar cell according to claim 1, characterized in that The first passivation layer is disposed between the second intrinsic amorphous silicon layer and the p-type microcrystalline silicon layer.

4. The solar cell according to claim 1, characterized in that The thickness of the first passivation layer is 5-8 nm.

5. The solar cell according to any one of claims 1 to 4, characterized in that: The area of ​​the first transparent conductive layer not covered with the first electrode is also covered with a second passivation layer, the second passivation layer.

6. The solar cell according to claim 5, characterized in that: The second passivation layer is aluminum oxide or zinc-doped aluminum oxide.

7. The solar cell according to any one of claims 1 to 4, characterized in that: The thickness of the first intrinsic amorphous silicon layer and the second intrinsic amorphous silicon layer are both 3-15 nm.

8. The solar cell according to any one of claims 1 to 4, characterized in that: The thickness of the n-type microcrystalline silicon layer is 10-40 nm, and the thickness of the p-type microcrystalline silicon layer is 15-45 nm.

9. The solar cell according to any one of claims 1 to 4, characterized in that: The thickness of the first transparent conductive layer is smaller than the thickness of the second transparent conductive layer.

10. The solar cell according to claim 9, characterized in that: The thickness of the first transparent conductive layer is 70-120 nm, and the thickness of the second transparent conductive layer is 80-140 nm.

11. The solar cell according to any one of claims 1 to 4, characterized in that: The first transparent conductive layer includes a nitrogen-doped zinc oxide layer, an indium tin oxide layer and a titanium oxide layer which are stacked in sequence. The nitrogen-doped zinc oxide layer is connected to the first electrode, and the titanium oxide layer is connected to the n-type microcrystalline silicon layer.

12. A photovoltaic module, characterized in that: A solar cell comprising the solar cell according to any one of claims 1 to 11.

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