Solar cell and method for manufacturing the same

Abstract

The present application relates to a solar cell and a method for preparing the same. The method comprises the following steps: circulating a first aluminum precursor and a first oxidant to form a first aluminum oxide layer on one side of a silicon substrate; circulating a second aluminum precursor and a second oxidant to form a second aluminum oxide layer on the side of the first aluminum oxide layer away from the silicon substrate; in each cycle, the flow rate of the second aluminum precursor is greater than the flow rate of the first aluminum precursor, and the flow rate of the second oxidant is greater than the flow rate of the first oxidant. This method can effectively improve the passivation effect of the first and second aluminum oxide layers, thereby effectively improving the photoelectric conversion efficiency of the solar cell.

Description

Technical Field

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

[0002] Silicon-based solar cells have become the mainstream in the current market due to their abundant silicon material reserves, stable performance, and mature manufacturing processes. Improving the photoelectric conversion efficiency of silicon-based solar cells has always been a research priority. In this process, the aluminum oxide layer plays a key role: On the one hand, the large number of dangling bonds and defect states on the silicon wafer surface lead to severe carrier recombination. The aluminum oxide layer, with its passivation properties, can reduce the surface recombination rate and increase the minority carrier lifetime. On the other hand, in complex cell structures, the coordination between the various functional layers is crucial. The aluminum oxide layer can optimize the interface characteristics and enhance the overall performance of the cell. However, aluminum oxide layers prepared by traditional methods have limited effect on improving the photoelectric conversion efficiency of solar cells. Summary of the Invention

[0003] Based on this, the present application provides a solar cell and a method for preparing the same. The method for preparing the solar cell can produce a solar cell with high photoelectric conversion efficiency.

[0004] The technical solution of this application to solve the above technical problems is as follows.

[0005] In a first aspect, the present application provides a method for preparing a solar cell, comprising the following steps:

[0006] Circulating a first aluminum precursor and a first oxidant to form a first aluminum oxide layer on one side of the silicon substrate;

[0007] Circulating a second aluminum precursor and a second oxidant to form a second aluminum oxide layer on a side of the first aluminum oxide layer away from the silicon substrate;

[0008] In each cycle, the flow rate of the second aluminum precursor is greater than the flow rate of the first aluminum precursor, and the flow rate of the second oxidant is greater than the flow rate of the first oxidant.

[0009] In some embodiments, in the method for preparing a solar cell, in each cycle, the flow rate of the first aluminum precursor is 14 sccm to 18 sccm, and the flow rate of the second aluminum precursor is 16 sccm to 20 sccm;

[0010] And / or, in each cycle, the flow rate of the first oxidant is 12 sccm-16 sccm, and the flow rate of the second oxidant is 16 sccm-22 sccm.

[0011] In some embodiments, in the method for preparing a solar cell, in each cycle, the pulse time of the second aluminum precursor is greater than the pulse time of the first aluminum precursor;

[0012] And / or, in each cycle, the pulse time of the second oxidant is greater than the pulse time of the first oxidant.

[0013] In some embodiments, in the method for preparing a solar cell, the number of cycles of the second aluminum precursor and the second oxidant is less than the number of cycles of the first aluminum precursor and the first oxidant.

[0014] In some embodiments, in the method for preparing a solar cell, in each cycle, the pulse time of the first aluminum precursor is 4 s to 8 s, and the pulse time of the second aluminum precursor is 5 s to 9 s;

[0015] And / or, in each cycle, the pulse time of the first oxidant is 3 s to 7 s, and the pulse time of the second oxidant is 4 s to 8 s;

[0016] And / or, the number of cycles of the first aluminum precursor and the first oxidant is 15 to 25 times, and the number of cycles of the second aluminum precursor and the second oxidant is 5 to 15 times.

[0017] In some embodiments, in the method for preparing a solar cell, the temperature for preparing the first aluminum oxide layer and the second aluminum oxide layer is independently 300° C. to 360° C.

[0018] In some embodiments, in the method for preparing a solar cell, the first aluminum precursor and the second aluminum precursor each independently include trimethylaluminum;

[0019] And / or, the first oxidant and the second oxidant each independently comprise water vapor.

[0020] In some embodiments, the method for preparing a solar cell includes, before circulating the first aluminum precursor and the first oxidant, introducing ozone to form a silicon oxide layer on one side of the silicon substrate.

[0021] In some embodiments, the method for preparing a solar cell includes, after preparing the silicon oxide layer and before circulating the first aluminum precursor and the first oxidant, performing a first pretreatment on the surface of the silicon oxide layer away from the silicon substrate by introducing water vapor;

[0022] And / or, after preparing the first aluminum oxide layer, before circulating the second aluminum precursor and the second oxidant, the method includes: introducing water vapor to perform a second pretreatment on the surface of the first aluminum oxide layer away from the silicon substrate.

[0023] A second aspect of the present application provides a solar cell, which is manufactured using the method for manufacturing a solar cell provided by the first aspect.

[0024] The preparation method of the solar cell provided in the present application circulates a first aluminum precursor and a first oxidant to prepare a first aluminum oxide layer on one side of a silicon substrate; circulates a second aluminum precursor and a second oxidant to prepare a second aluminum oxide layer on the side of the first aluminum oxide layer away from the silicon substrate; by controlling the flow rate of the second aluminum precursor to be greater than the flow rate of the first aluminum precursor and the flow rate of the second oxidant to be greater than the flow rate of the first oxidant in each cycle, the passivation effect of the first aluminum oxide layer and the second aluminum oxide layer is effectively improved, thereby effectively improving the photoelectric conversion efficiency of the solar cell. DETAILED DESCRIPTION

[0025] The present application will be further described in detail below in conjunction with the embodiments and examples. It should be understood that these embodiments and examples are only intended to illustrate the present application and are not intended to limit the scope of the present application. The purpose of providing these embodiments and examples is to provide a more thorough and comprehensive understanding of the disclosure of the present application.

[0026] It should also be understood that the present application can be implemented in many different forms and is not limited to the embodiments and examples described herein. Those skilled in the art can make various changes or modifications without violating the connotation of the present application, and the resulting equivalent forms also fall within the scope of protection of the present application. For example, features illustrated or described as part of one embodiment can be combined in a suitable manner in another embodiment to produce a new embodiment. In addition, in the description below, a large number of specific details are given in order to provide a more complete understanding of the present application. It should be understood that the present application can be implemented without one or more of these details.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing embodiments and examples only and are not intended to limit this application.

[0028] Unless otherwise specified or incompatible herewith, the terms and phrases used herein shall have the following meanings:

[0029] In this application, "plurality", "multiple", "multiple times", etc., unless otherwise specified, refer to a quantity greater than or equal to 2. For example, "one or more" means one or more than or equal to two.

[0030] As used herein, "combination thereof", "any combination thereof", "any combination thereof" and the like include all suitable combinations of any two or more of the listed items.

[0031] Herein, the “suitable” mentioned in “suitable combination”, “suitable method”, “any suitable method”, etc. shall be based on the ability to implement the technical solution of this application, solve the technical problems of this application, and achieve the expected technical effects of this application.

[0032] In this application, "further", "further", "particularly" and the like are used for descriptive purposes to indicate differences in content, but should not be understood as limiting the scope of protection of this application.

[0033] In this application, the terms "first," "second," "third," "fourth," etc. in "the first aspect," "the second aspect," "the third aspect," "the fourth aspect," etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or quantity, nor should they be understood as implicitly indicating the importance or quantity of the indicated technical features. Furthermore, "first," "second," "third," "fourth," etc. serve only as non-exhaustive enumeration and description, and should be understood not to constitute a closed-ended limitation on quantity.

[0034] In this application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0035] In this application, when referring to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​within the numerical interval is deemed to be continuous and includes the two numerical endpoints of the numerical interval (i.e., the minimum and maximum values), as well as every numerical value between these two numerical endpoints. Unless otherwise specified, when a numerical interval refers only to integers within the numerical interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints, which is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe a feature or characteristic, these numerical ranges can be combined. In other words, unless otherwise specified, the numerical ranges disclosed herein should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. "Numerical interval" allows for a broad range of numerical interval types including percentage intervals, ratio intervals, and ratio intervals.

[0036] Unless otherwise specified, the temperature parameters in this application allow for both constant temperature treatment and temperature fluctuations within a certain temperature range. It should be understood that the constant temperature treatment allows for temperature fluctuations within the accuracy range of instrument control. Fluctuations within ranges such as ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are permitted.

[0037] In this application, the term "room temperature" or "normal temperature" generally refers to 4°C to 35°C, for example, 20°C ± 5°C. In some embodiments of this application, "room temperature" or "normal temperature" refers to 10°C to 30°C. In some embodiments of this application, "room temperature" or "normal temperature" refers to 20°C to 30°C.

[0038] In this application, when referring to a range of units, if the unit is only after the right endpoint, it means that the units of the left and right endpoints are the same. For example, 3~5h means that the units of the left endpoint "3" and the right endpoint "5" are both hours.

[0039] All documents mentioned in this application are cited as references in this application, just as each document is cited as a reference individually. Unless they conflict with the invention purpose and / or technical solution of this application, the cited documents involved in this application are cited in their entirety and for all purposes. When cited documents are involved in this application, the definitions of relevant technical features, terms, nouns, phrases, etc. in the cited documents are also cited. When cited documents are involved in this application, the examples and preferred embodiments of the cited relevant technical features may also be incorporated into this application as references, but are limited to the ability to implement this application. It should be understood that when the cited content conflicts with the description in this application, the present application shall prevail or be adaptively amended according to the description in this application.

[0040] The mass or weight of the relevant components mentioned in the examples of this application may not only refer to the specific content of each component, but also represent the proportional relationship of the mass or weight of each component. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the examples of this application, it is within the scope disclosed in the examples of this application. Specifically, the mass or weight described in the examples of this application may be units known in the chemical industry such as μg, mg, g, and kg.

[0041] An embodiment of the present application provides a method for preparing a solar cell, comprising the following steps:

[0042] Step S100: circulate a first aluminum precursor and a first oxidant to form a first aluminum oxide layer on one side of a silicon substrate;

[0043] Step S200: circulate a second aluminum precursor and a second oxidant to form a second aluminum oxide layer on a side of the first aluminum oxide layer away from the silicon substrate;

[0044] In each cycle, the flow rate of the second aluminum precursor is greater than the flow rate of the first aluminum precursor, and the flow rate of the second oxidant is greater than the flow rate of the first oxidant.

[0045] By controlling the flow rate of the second aluminum precursor to be greater than the flow rate of the first aluminum precursor and the flow rate of the second oxidant to be greater than the flow rate of the first oxidant in each cycle, the passivation effect of the first aluminum oxide layer and the second aluminum oxide layer is effectively improved, thereby effectively improving the photoelectric conversion efficiency of the solar cell.

[0046] The flow rate of the second aluminum precursor is greater than that of the first aluminum precursor. The flow rate of the first aluminum precursor is smaller. The greater the adsorption ratio of the first aluminum precursor on the deposition surface, the less unabsorbed residue there is, which effectively improves the atmosphere concentration in the reaction chamber, and avoids the first oxidant being consumed by by-products due to the reaction with the residual unabsorbed first aluminum precursor to generate aluminum oxide powder after the first oxidant is introduced, thereby promoting the complete self-limiting reaction, further controlling the increase in the flow rate of the second aluminum precursor, and effectively improving the density of the film and the ability of hydrogen passivation.

[0047] It is understood that sequentially introducing the first aluminum precursor and the first oxidant constitutes a cycle; sequentially introducing the second aluminum precursor and the second oxidant constitutes a cycle. It is further understood that the aluminum precursor and the oxidant react to form aluminum oxide. It is understood that in some examples, in the solar cell fabrication methods, the first aluminum precursor, the first oxidant, the second aluminum precursor, and the second oxidant are all in a gaseous state. It is further understood that the first aluminum oxide layer and the second aluminum oxide layer are formed by ALD (atomic layer deposition).

[0048] Atomic layer deposition (ALD) is a nano-thin film deposition technology based on the chemical adsorption of gaseous precursors on the surface of a silicon substrate. An aluminum oxide film layer of a certain thickness is obtained through a self-limiting reaction.

[0049] ALD is based on the principle of surface self-limiting reaction, which forms atomic-level thin films by alternately introducing two or more precursors and causing them to undergo chemical adsorption reactions. Taking trimethylaluminum (TMA) as the first and second aluminum precursors, and water (H2O) as the first and second oxidants, as an example, trimethylaluminum (TMA) is first introduced into the reaction chamber. The aluminum atoms in TMA react with hydroxyl groups or other active sites on the surface of the silicon substrate, forming chemical bonds and adsorbing on the surface. Due to the limited number of surface active sites, when these sites are completely occupied by TMA molecules, a saturated monolayer is formed. At this point, even if more TMA molecules are introduced, the adsorption reaction cannot continue. This is the first self-limitation. An inert gas is then introduced to purge the unreacted TMA molecules and byproducts. After that, water (H2O) is introduced. The oxygen in the water molecules reacts with the adsorbed aluminum atoms to form part of the aluminum oxide, while releasing byproducts such as methane. This reaction also occurs only in the adsorbed TMA layer and will not react indefinitely at other locations. This is the second self-limitation. After another purge, a deposition cycle is completed, and this process is repeated to achieve layer-by-layer growth of the thin film.

[0050] In some of the examples, in the method for preparing a solar cell, the flow rate of the first aluminum precursor is 14 sccm to 18 sccm in each cycle.

[0051] It is understood that in each cycle, the flow rate of the first aluminum precursor includes, but is not limited to, 14 sccm, 15 sccm, 16 sccm, 17 sccm, and 18 sccm. It is also understood that the flow rate of the first aluminum precursor in each cycle may be the same or different; in some embodiments, the flow rate of the first aluminum precursor in each cycle is the same. The same shall apply hereinafter.

[0052] In some of the examples, in the method for preparing a solar cell, the flow rate of the second aluminum precursor is 16 sccm to 20 sccm in each cycle.

[0053] It can be understood that in each cycle, the flow rate of the second aluminum precursor includes but is not limited to 16 sccm, 17 sccm, 18 sccm, 19 sccm, and 20 sccm.

[0054] In some examples, in the method for preparing a solar cell, a flow rate of the first oxidant is 12 sccm to 16 sccm in each cycle.

[0055] It can be understood that in each cycle, the flow rate of the first oxidant includes but is not limited to 12 sccm, 13 sccm, 14 sccm, 15 sccm, and 16 sccm.

[0056] In some of the examples, in the method for preparing a solar cell, a flow rate of the second oxidant is 16 sccm to 22 sccm in each cycle.

[0057] It can be understood that in each cycle, the flow rate of the second oxidant includes but is not limited to 16 sccm, 17 sccm, 18 sccm, 19 sccm, 20 sccm, 21 sccm, and 22 sccm.

[0058] In some examples, in the method for preparing a solar cell, in each cycle, the pulse time of the second aluminum precursor is greater than the pulse time of the first aluminum precursor.

[0059] By controlling the pulse time, the self-limiting reaction of ALD atomic layer deposition can be carried out efficiently.

[0060] In some of these examples, in the solar cell fabrication method, the pulse time of the first aluminum precursor in each cycle is 4 s to 8 s.

[0061] It can be understood that in each cycle, the pulse time of the first aluminum precursor includes but is not limited to 4 s, 5 s, 6 s, 7 s, and 8 s.

[0062] In some of these examples, in the solar cell fabrication method, the pulse time of the second aluminum precursor in each cycle is 5 s to 9 s.

[0063] It can be understood that in each cycle, the pulse time of the second aluminum precursor includes but is not limited to 5 s, 6 s, 7 s, and 8 s.

[0064] In some examples, in the method for preparing a solar cell, in each cycle, a pulse time of the second oxidant is greater than a pulse time of the first oxidant.

[0065] In some of the examples, in the method for preparing a solar cell, the pulse time of the first oxidant in each cycle is 3 s to 7 s.

[0066] It can be understood that in each cycle, the pulse time of the first oxidant includes but is not limited to 3 s, 4 s, 5 s, 6 s, and 7 s.

[0067] In some of these examples, in the method for preparing a solar cell, the pulse time of the second oxidant in each cycle is 4 s to 8 s.

[0068] It can be understood that in each cycle, the pulse time of the second oxidant includes but is not limited to 4 s, 5 s, 6 s, 7 s, and 8 s.

[0069] In some examples, in the method for preparing a solar cell, the number of cycles of the second aluminum precursor and the second oxidant is less than the number of cycles of the first aluminum precursor and the first oxidant.

[0070] On the basis of controlling the flow rate of the second aluminum precursor to be greater than the flow rate of the first aluminum precursor and the flow rate of the second oxidant to be greater than the flow rate of the first oxidant in each cycle, the pulse time of the second aluminum precursor is further controlled to be greater than the pulse time of the first aluminum precursor, the pulse time of the second oxidant is greater than the pulse time of the first oxidant, and the number of cycles of the second aluminum precursor and the second oxidant is controlled to be less than the number of cycles of the first aluminum precursor and the first oxidant, thereby ensuring the inherent negative charge density inside the first aluminum oxide layer and the second aluminum oxide layer and improving the field passivation effect.

[0071] In some of the examples, in the method for preparing a solar cell, the number of cycles of the first aluminum precursor and the first oxidant is 15 to 25 times.

[0072] It can be understood that in each cycle, the number of cycles of the first aluminum precursor and the first oxidant includes but is not limited to 15 times, 18 times, 20 times, and 25 times.

[0073] In some of the examples, in the method for preparing a solar cell, the number of cycles of the second aluminum precursor and the second oxidant is 5 to 15 times.

[0074] It can be understood that in each cycle, the number of cycles of the second aluminum precursor and the second oxidant includes but is not limited to 5 times, 8 times, 10 times, and 15 times.

[0075] In some examples, in the method for preparing a solar cell, the temperature for preparing the first aluminum oxide layer and the second aluminum oxide layer is independently 300° C. to 360° C.

[0076] It can be understood that the temperature for preparing the first aluminum oxide layer and the temperature for preparing the second aluminum oxide layer can be the same or different; further, the temperature for preparing the first aluminum oxide layer and the second aluminum oxide layer independently includes but is not limited to 300°C, 305°C, 310°C, 315°C, 320°C, 325°C, 330°C, 335°C, 340°C, 345°C, 350°C, 355°C, and 360°C; in some examples, any two of these point values ​​can be within the range formed by the end values, the same below.

[0077] It can be understood that in the process of raising the temperature to the temperature for preparing the first aluminum oxide layer and the second aluminum oxide layer, the surface layer of the silicon substrate will be oxidized to form silicon dioxide (the defect density between silicon dioxide and the silicon substrate is less than the defect density between the aluminum oxide layer and the silicon substrate). By controlling the temperature for preparing the first aluminum oxide layer and the second aluminum oxide layer to be within a higher range (300°C~360°C), the defect density between silicon dioxide and the silicon substrate can be further reduced, resulting in reorganization of the internal structure of the first aluminum oxide layer and the second aluminum oxide layer, and increasing the inherent negative charge concentration within the first aluminum oxide layer and the second aluminum oxide layer. At the same time, it is beneficial to increase the activation energy of the precursor on the surface of the silicon substrate during the aluminum oxide deposition process, enhance the frequency and amount of chemical adsorption, improve the field passivation performance of the first aluminum oxide layer and the second aluminum oxide layer, increase the density of the first aluminum oxide layer and the second aluminum oxide layer, and improve the battery opening voltage and fill factor; and enhance the diffusion energy of H atoms in the first aluminum oxide layer and the second aluminum oxide layer, promote the combination of H and dangling bonds on the silicon surface, reduce the defect density on the silicon surface, thereby enhancing the chemical passivation effect of the first aluminum oxide layer and the second aluminum oxide layer, and thus improving the battery efficiency.

[0078] The first aluminum oxide layer is prepared at a higher temperature, the flow rate of the first aluminum precursor is reduced, and the pulse time of the first aluminum precursor is shortened, so that the first aluminum precursor has a better adsorption effect on the surface of the silicon substrate, promotes dangling bond bonding on the surface of the silicon substrate, and promotes the ability of the first oxidant to react with it; the second aluminum oxide layer is prepared at a higher temperature, the flow rate of the second aluminum precursor is reduced, and the pulse time of the second aluminum precursor is shortened, so that the second aluminum precursor has a better adsorption effect on the surface of the silicon substrate, promotes the ability of the second oxidant to react with it and its adhesion ability; and thereby promotes the interface state density and passivation ability of the first aluminum oxide layer and the second aluminum oxide layer.

[0079] Compared with the preparation of the first and second aluminum oxide layers at higher temperatures (300℃~360℃), the adsorption effect of the aluminum precursor deposited at lower temperatures (<300℃) is weakened, and the dangling bonds on the surface of the silicon substrate are not completely bonded, and some dangling bonds are still exposed; when the oxidant is introduced, the ability to undergo chemical reaction or adhesion is correspondingly weakened, which ultimately causes the density of the aluminum oxide film layer to weaken. Similarly, the field passivation and chemical passivation capabilities are weakened.

[0080] Furthermore, the temperatures for preparing the first aluminum oxide layer and the second aluminum oxide layer are independently 310° C. to 340° C.

[0081] By controlling the flow rate, pulse time and number of cycles of the first aluminum precursor, the first oxidant, the second aluminum precursor and the second oxidant, as well as controlling the deposition temperature, the passivation effect of the aluminum oxide passivation layer can be effectively improved, thereby improving battery performance.

[0082] In some examples, in step S100, before circulating the first aluminum precursor and the first oxidant, the process includes step S110:

[0083] Ozone is introduced to form a silicon oxide layer on one side of the silicon substrate.

[0084] Before the ALD process (before the first aluminum precursor and the first oxidant are circulated), ozone is introduced during the process of raising the temperature to the temperature for preparing the first aluminum oxide layer and the second aluminum oxide layer, so as to generate a silicon dioxide layer on the surface of the silicon substrate. Combined with the high reaction temperature, this is beneficial to improving the density of the silicon dioxide. The generated silicon dioxide layer is also beneficial to improving the density of the aluminum oxide film (the first aluminum oxide layer and the second aluminum oxide layer) when depositing aluminum oxide, thereby improving the passivation performance of the first aluminum oxide layer and the second aluminum oxide layer.

[0085] In some examples, in step S110 , the concentration of the introduced ozone is 1000 ppb to 3000 ppb, and the time range of the ozone introduction is 500 s to 2000 s.

[0086] In some examples, in the method for preparing a solar cell, the first aluminum precursor and the second aluminum precursor each independently include trimethylaluminum.

[0087] In some examples, in the method for preparing a solar cell, the first oxidant and the second oxidant each independently include water vapor.

[0088] In some examples, step S100, after preparing the silicon oxide layer in step S110 and before circulating the first aluminum precursor and the first oxidant, includes step S120:

[0089] Water vapor is introduced to perform a first pretreatment on the surface of the silicon oxide layer away from the silicon substrate.

[0090] The silicon oxide layer is first pretreated with water vapor to provide hydrogen atoms to saturate unbonded dangling bonds in the silicon oxide layer.

[0091] In some examples, any one loop of step S100 includes steps S120 to S160:

[0092] Step S120: introducing water vapor to perform a first pretreatment on the surface of the silicon oxide layer away from the silicon substrate;

[0093] Step S130: introducing a first aluminum precursor, and the first aluminum precursor is adsorbed on the surface of the silicon oxide layer;

[0094] Step S140: introducing a purge gas to remove unadsorbed gas;

[0095] Step S150: introducing a first oxidant to react with the first aluminum precursor adsorbed on the surface of the silicon oxide layer to form a first aluminum oxide layer;

[0096] Step S160: introducing purge gas to remove residual gas.

[0097] In some examples, after preparing the first aluminum oxide layer in step S200 and before circulating the second aluminum precursor and the second oxidant, step S210 is included: introducing water vapor to perform a second pretreatment on the surface of the first aluminum oxide layer away from the silicon substrate.

[0098] In some examples, any one loop of step S200 includes steps S210 to S250:

[0099] Step S210: introducing water vapor to perform a second pretreatment on the surface of the first aluminum oxide layer away from the silicon substrate;

[0100] Step S220: introducing a second aluminum precursor, and the second aluminum precursor is adsorbed on the surface of the first aluminum oxide layer;

[0101] Step S230: introducing a purge gas to remove unadsorbed gas;

[0102] Step S240: introducing a second oxidant to react with the second aluminum precursor adsorbed on the surface of the first aluminum oxide layer to form a second aluminum oxide layer;

[0103] Step S250: introducing purge gas to remove residual gas.

[0104] In some examples, the method for preparing a solar cell includes, before step S100, step S300:

[0105] Boron is diffused on the front side of the silicon substrate to form the emitter.

[0106] In some examples, the boron diffusion uses a boron source including, but not limited to, BBr 3 or BCl 3 .

[0107] It can be understood that in some examples, before step S300 , a step of texturing the silicon wafer to obtain a silicon substrate is included.

[0108] Silicon wafers are textured to remove organic and metal impurities on the surface of the silicon wafers, reduce recombination centers, form an uneven textured surface, increase the silicon wafer's absorption of sunlight, and reduce reflectivity; further, the anisotropic corrosion characteristics of silicon in low-concentration alkaline solution are utilized to form a pyramid textured surface on the silicon wafer surface.

[0109] In some examples, the method for preparing a solar cell includes, after step S100, step S400:

[0110] A tunneling oxide layer and a doped polysilicon layer are sequentially prepared on the back side of the silicon substrate.

[0111] A tunneling oxide layer and a doped polysilicon layer are deposited on the back of the silicon wafer to provide good interface passivation and provide tunneling barriers for different carriers.

[0112] In some examples, step S400 includes: first depositing a tunnel oxide layer, then depositing amorphous silicon, and finally diffusing phosphorus (while the amorphous silicon is converted into polysilicon).

[0113] In some examples, after phosphorus diffusion and before step S100 , the process includes removing the front and edge BSG.

[0114] In some examples, the method for preparing a solar cell includes, after step S400, step S500:

[0115] A front anti-reflection layer is formed on a side of the second aluminum oxide layer away from the first aluminum oxide layer, and a back anti-reflection layer is formed on a side of the polysilicon layer away from the tunneling oxide layer.

[0116] In some examples, in the method for preparing a solar cell, after step S500 , a front electrode and a metal back electrode are prepared.

[0117] The method for preparing solar cells provided in this application has high production efficiency and can achieve an efficiency gain of more than 0.05%.

[0118] One embodiment of the present application provides a solar cell, which is manufactured using the above-mentioned solar cell manufacturing method.

[0119] It can be understood that the solar cell includes a silicon substrate, and one side of the silicon substrate includes a first aluminum oxide layer and a second aluminum oxide layer arranged in sequence.

[0120] In some of these examples, in the solar cell, the mass of aluminum in the second aluminum oxide layer is lower than the mass of aluminum in the first aluminum oxide layer.

[0121] In some of these examples, in the solar cell, the mass of oxygen in the second aluminum oxide layer is lower than the mass of oxygen in the first aluminum oxide layer.

[0122] In some of the examples, in the solar cell, the mass ratio of aluminum in the first aluminum oxide layer to aluminum in the second aluminum oxide layer is (1.2~2):1.

[0123] It can be understood that the mass ratio of aluminum in the second aluminum oxide layer to aluminum in the first aluminum oxide layer includes but is not limited to 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, and 2:1.

[0124] By controlling the mass relationship between the aluminum in the second aluminum oxide layer and the first aluminum oxide layer, it is beneficial to ensure the inherent negative charge density inside the first aluminum oxide layer and the second aluminum oxide layer, thereby improving the field passivation effect.

[0125] In some examples, the solar cell includes but is not limited to at least one of a crystalline silicon cell and a perovskite cell. It is understood that the crystalline silicon cell includes but is not limited to at least one of a TOPCon cell (tunneling oxide passivation contact cell), an HJT cell (heterojunction cell), an IBC cell (interdigitated back contact cell), and a PERC cell (passivated emitter and rear cell).

[0126] In some of these examples, the solar cell is a TOPCON cell (Tunneling Oxide Passivated Contact cell).

[0127] TOPCon (tunnel oxide passivation contact) battery is the full name of tunneling oxide passivation contact battery. Its core lies in the ultra-thin tunneling oxide layer and heavily doped polysilicon layer on the back. The ultra-thin oxide layer can allow electrons to tunnel into the polysilicon layer, while blocking the transport of holes, reducing the recombination rate, and improving the passivation effect and conversion efficiency of the battery.

[0128] In some examples, the solar cell includes a silicon substrate, the front side of the silicon substrate includes an emitter, a silicon oxide layer, a first aluminum oxide layer, and a second aluminum oxide layer arranged in sequence, and the back side of the silicon substrate includes a tunneling oxide layer and a polysilicon layer arranged in sequence.

[0129] In some examples, the solar cell further comprises a front anti-reflection layer and a front electrode sequentially disposed on a surface of the second aluminum oxide layer away from the first aluminum oxide layer. In some examples, the front anti-reflection layer comprises but is not limited to silicon nitride (SiN x In some examples, the front electrode includes but is not limited to at least one of aluminum and silver.

[0130] In some examples, the solar cell further includes a back anti-reflection layer and a metal back electrode sequentially disposed on a surface of the polysilicon layer away from the tunnel oxide layer. In some examples, the back anti-reflection layer includes but is not limited to silicon nitride (SiN x In some examples, the metal back electrode includes, but is not limited to, silver.

[0131] One embodiment of the present application provides a stacked cell, including the above-mentioned solar cell or a solar cell prepared by the above-mentioned method for preparing a solar cell.

[0132] It is understood that the tandem battery includes but is not limited to a two-terminal tandem battery, a three-terminal tandem battery, and a four-terminal tandem battery. Further, the tandem battery includes but is not limited to a perovskite battery superimposed on a crystalline silicon battery.

[0133] One embodiment of the present application provides a photovoltaic module, including the solar cell provided above, a solar cell prepared by the method for preparing a solar cell provided above, or a laminated cell provided above.

[0134] Some examples of PV panels include:

[0135] A cell string is formed by electrically connecting a plurality of the above solar cells or solar cells produced by the above solar cell production method, or by electrically connecting a plurality of the above stacked cells;

[0136] Encapsulation film, used to cover the surface of the battery string; and

[0137] The cover plate is used to cover the surface of the packaging film facing away from the battery string.

[0138] It is understood that solar cells or laminated cells are electrically connected in the form of a whole cell or multiple slices to form multiple cell strings, and multiple cell strings are electrically connected in series and / or parallel. Furthermore, solar cells or laminated cells can be whole cells or sliced ​​cells. Sliced ​​cells refer to cells formed by cutting a complete whole cell.

[0139] In some examples, multiple battery strings may be electrically connected via conductive ribbons.

[0140] In some examples, the encapsulation film includes a first encapsulation layer and a second encapsulation layer, the first encapsulation layer covers one of the front and back sides of the battery, and the second encapsulation layer covers the other of the front and back sides of the battery; further, the first encapsulation layer and the second encapsulation layer can independently include at least one of organic encapsulation films such as polyvinyl butyral (PVB) film, ethylene-vinyl acetate copolymer (EVA) film, polyethylene octene co-elastomer (POE) film and polyethylene terephthalate (PET) film.

[0141] In some examples, the cover plate may be a glass cover plate, a plastic cover plate, or other cover plate with a light-transmitting function.

[0142] The present application will be described in further detail below in conjunction with specific implementation methods, but the implementation methods of the present application are not limited thereto.

[0143] In the following examples and comparative examples, the first aluminum precursor and the second aluminum precursor are both trimethylaluminum (TMA), and the first oxidant and the second oxidant are both water vapor.

[0144] Example 1

[0145] (1) Texturing of n-type silicon wafers;

[0146] Boron diffusion: Diffuse p-type elements (boron) on n-type silicon wafers to form a pn junction and a p+ layer on the front side;

[0147] Alkali polishing: remove BSG from the edge and back of the silicon wafer;

[0148] LPCVD: Deposition of tunnel oxide and polysilicon layers on the back of the silicon wafer;

[0149] Phosphorus diffusion: phosphorus doping of polysilicon layer;

[0150] Front etching: positive groove etching (adding water film), water washing, alkali washing, water washing, acid washing, water washing and drying to remove the front and edge BSG;

[0151] (2) Ozone was introduced into the drying tank of the wet process equipment at a flow rate of 1200 ppb for 900 s to form the first silicon oxide layer;

[0152] (3) ALD deposition was performed, preheated to a deposition temperature of 325°C (a second silicon oxide layer was formed during this process), and the first aluminum oxide layer and the second aluminum oxide layer were prepared in sequence:

[0153] (3.1) Pre-treat the surface of the silicon oxide layer by introducing water vapor into the atomic layer deposition chamber at a flow rate of 12 sccm and a pulse duration of 25 s, followed by an inert gas purge for 12 s.

[0154] (3.2) Cyclic introduction of the first aluminum precursor and the first oxidant. Each cycle consists of: introducing the first aluminum precursor at a flow rate of 16 sccm, a pulse time of 6 s, and an inert gas purge for 12 s; then introducing the first oxidant at a flow rate of 14 sccm, a pulse time of 5 s, and an inert gas purge for 12 s. This cycle is repeated 18 times to form the first aluminum oxide layer.

[0155] (3.3) Pre-treat the surface of the first aluminum oxide layer by introducing water vapor into the atomic layer deposition chamber at a flow rate of 12 sccm and a pulse duration of 25 s, followed by an inert gas purge for 12 s.

[0156] (3.4) Cyclic introduction of a second aluminum precursor and a second oxidant. Each cycle consists of the following steps: introducing the second aluminum precursor at a flow rate of 18 sccm, a pulse duration of 7 s, and purging with an inert gas for 12 s; then introducing the second oxidant at a flow rate of 20 sccm, a pulse duration of 6 s, and purging with an inert gas for 12 s. This cycle is repeated 10 times to form a second aluminum oxide layer.

[0157] (4) Front and back film: Si3H4 anti-reflection film is formed on the surface of silicon wafer;

[0158] Screen-printed positive and negative electrodes.

[0159] Example 1 The micro-conducting process parameters for preparing the first aluminum oxide layer and the second aluminum oxide layer are shown in Table 1.

[0160] Table 1

[0161]

[0162] Example 2

[0163] The process is basically the same as Example 1, except that, in the preparation of the first aluminum oxide layer and the second aluminum oxide layer, the pulse time of the first aluminum precursor is 7 s, and the pulse time of the second aluminum precursor is 6 s.

[0164] Example 3

[0165] The method is basically the same as Example 1, except that, in the preparation of the first aluminum oxide layer and the second aluminum oxide layer, the pulse time of the first oxidant is 6 s, and the pulse time of the second oxidant is 5 s.

[0166] Example 4

[0167] It is basically the same as Example 1, except that in the preparation of the first aluminum oxide layer and the second aluminum oxide layer, the number of cycles of circulating the first aluminum precursor and the first oxidant is 10 times, and the number of cycles of circulating the second aluminum precursor and the second oxidant is 18 times.

[0168] Example 5

[0169] The process is basically the same as Example 1, except that the deposition temperature is 300°C.

[0170] Example 6

[0171] The method is basically the same as Example 1, except that the step of introducing ozone in step (2) is omitted, and the first silicon oxide layer is formed during the process of preheating to the ALD deposition temperature.

[0172] Example 7

[0173] The process is basically the same as Example 1, except that the deposition temperature is 265°C.

[0174] Comparative Example 1

[0175] Prepare the aluminum oxide layer according to the parameters in Table 2:

[0176] Table 2

[0177]

[0178] Comparative Example 2

[0179] The process is basically the same as Example 1, except that the flow rate of the first aluminum precursor is 18 sccm, and the flow rate of the second aluminum precursor is 16 sccm.

[0180] Comparative Example 3

[0181] The process is basically the same as that of Example 1, except that the flow rate of the first oxidant is 20 sccm, and the flow rate of the second oxidant is 14 sccm.

[0182] Use a battery performance tester, AM1.5G spectrum, light intensity 1000W / m 2 The electrical performance of the solar cells prepared in each embodiment and comparative example was tested, where Eta is the photoelectric conversion efficiency, Uoc is the open circuit voltage, Isc is the short circuit current, and FF is the fill factor; the results are shown in Table 3.

[0183] Table 3

[0184]

[0185] It can be seen from Table 3 that, compared with Comparative Example 1, the photoelectric conversion efficiency of the batteries prepared in each embodiment is higher.

[0186] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0187] The embodiments described above only express several implementation methods of the present application, which are convenient for understanding the technical solutions of the present application in a specific and detailed manner, but they cannot be understood as limiting the scope of protection of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present application, several variations and improvements can be made, which all fall within the scope of protection of the present application. It should be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided in the present application are all within the scope of protection of the claims attached to the present application. Therefore, the scope of protection of the patent of this application shall be based on the content of the attached claims, and the description can be used to interpret the content of the claims.

Claims

1. A method for preparing a solar cell, characterized in that: The steps include: Circulating a first aluminum precursor and a first oxidant to form a first aluminum oxide layer on one side of the silicon substrate; Circulating a second aluminum precursor and a second oxidant to form a second aluminum oxide layer on a side of the first aluminum oxide layer away from the silicon substrate; In each cycle, the flow rate of the second aluminum precursor is greater than the flow rate of the first aluminum precursor, the flow rate of the second oxidant is greater than the flow rate of the first oxidant, the pulse time of the second aluminum precursor is greater than the pulse time of the first aluminum precursor, and the pulse time of the second oxidant is greater than the pulse time of the first oxidant; The number of cycles of the second aluminum precursor and the second oxidant is less than the number of cycles of the first aluminum precursor and the first oxidant, the number of cycles of the first aluminum precursor and the first oxidant is 15 to 25 times, and the number of cycles of the second aluminum precursor and the second oxidant is 5 to 15 times; Before the first aluminum precursor and the first oxidant are circulated, the method includes: introducing ozone to prepare a silicon oxide layer on one side of the silicon substrate; The temperatures for preparing the first aluminum oxide layer and the second aluminum oxide layer are independently 320° C. to 340° C.

2. The method for preparing a solar cell according to claim 1, wherein: In each cycle, the flow rate of the first aluminum precursor is 14 sccm to 18 sccm, and the flow rate of the second aluminum precursor is 16 sccm to 20 sccm; And / or, in each cycle, the flow rate of the first oxidant is 12 sccm-16 sccm, and the flow rate of the second oxidant is 16 sccm-22 sccm.

3. The method for preparing a solar cell according to claim 1, wherein: The concentration of the ozone introduced is 1000 ppb to 3000 ppb, and the time for introducing the ozone is 500 s to 2000 s.

4. The method for preparing a solar cell according to claim 1, wherein: In each cycle, the pulse time of the first aluminum precursor is 4 s to 8 s, and the pulse time of the second aluminum precursor is 5 s to 9 s; And / or, in each cycle, the pulse time of the first oxidant is 3 s to 7 s, and the pulse time of the second oxidant is 4 s to 8 s.

5. The method for preparing a solar cell according to any one of claims 1 to 4, wherein: The temperatures for preparing the first aluminum oxide layer and the second aluminum oxide layer are independently 325° C. to 330° C.

6. The method for preparing a solar cell according to any one of claims 1 to 4, wherein: The mass of aluminum in the second aluminum oxide layer is lower than the mass of aluminum in the first aluminum oxide layer.

7. The method for preparing a solar cell according to claim 6, wherein: The mass ratio of aluminum in the first aluminum oxide layer to aluminum in the second aluminum oxide layer is (1.2-2):

1.

8. The method for preparing a solar cell according to any one of claims 1 to 4 and 7, wherein: The first aluminum precursor and the second aluminum precursor each independently include trimethylaluminum; And / or, the first oxidant and the second oxidant each independently comprise water vapor.

9. The method for preparing a solar cell according to any one of claims 1 to 4 and 7, wherein: After preparing the silicon oxide layer and before circulating the first aluminum precursor and the first oxidant, the method includes: introducing water vapor to perform a first pretreatment on the surface of the silicon oxide layer away from the silicon substrate; And / or, after preparing the first aluminum oxide layer, before circulating the second aluminum precursor and the second oxidant, the method includes: introducing water vapor to perform a second pretreatment on the surface of the first aluminum oxide layer away from the silicon substrate.

10. A solar cell, characterized in that: The solar cell is prepared by the method for preparing the solar cell according to any one of claims 1 to 9.

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