Solar cell front passivation layer, preparation method of solar cell front passivation layer, solar cell and preparation method of solar cell

Abstract

The invention relates to a solar cell front passivation layer and a preparation method thereof, a solar cell and a preparation method thereof. The preparation method of the front passivation layer of the solar cell comprises the following steps: introducing water vapor to carry out purging and water vapor oxidation on an emitter of a silicon wafer to obtain a silicon dioxide layer; depositing a passivation layer on the surface of the silicon dioxide layer; wherein the water vapor oxidation conditions are as follows: the temperature is controlled to be 300-400 DEG C, the flow rate of the water vapor is 5-30sccm, the introduction time is 5-15s, and the water vapor is introduced at least twice. Before the passivation layer is deposited, water vapor is adopted to carry out blowing and water vapor oxidation on the surface of the emitter of the silicon wafer, impurities on the surface of the emitter can be removed, a compact silicon dioxide layer can be formed on the surface of the emitter, surface defects can be repaired, and therefore the conversion efficiency of the solar cell can be effectively improved, and the service life of the solar cell is prolonged. And meanwhile, EL pollution of the solar cell can be obviously improved.

Description

Technical Field

[0001] The invention relates to the technical field of solar cells, and in particular to a solar cell front passivation layer and a preparation method thereof, a solar cell and a preparation method thereof. Background Art

[0002] For crystalline silicon solar cells, with the improvement of crystalline silicon manufacturing technology, the carrier lifetime of the substrate silicon wafer continues to increase, and is no longer the key factor restricting the improvement of battery efficiency, making the effect of battery surface passivation on conversion efficiency more and more obvious. Therefore, the surface passivation of crystalline silicon solar cells has always been the top priority of design and optimization, and is currently the main direction for improving the conversion efficiency of solar cells. Summary of the invention

[0003] Based on this, it is necessary to provide a solar cell front passivation layer and a preparation method thereof, as well as a solar cell and a preparation method thereof to address the above problems, which can not only effectively improve the conversion efficiency of the solar cell, but also significantly improve the EL pollution of the solar cell.

[0004] According to a first aspect of the present invention, there is provided a method for preparing a front passivation layer of a solar cell, comprising the following steps:

[0005] Water vapor is introduced to purge and oxidize the emitter of the silicon wafer to obtain a silicon dioxide layer;

[0006] Depositing a passivation layer on the surface of the silicon dioxide layer;

[0007] The conditions for water vapor oxidation are as follows: the temperature is controlled at 300° C. to 400° C., the flow rate of the water vapor is 5 sccm to 30 sccm, the introduction time is 5 s to 15 s, and the water vapor is introduced at least twice.

[0008] In one embodiment, during the water vapor oxidation process, the water vapor is introduced 10 to 15 times;

[0009] And / or, the interval between two times of introducing the water vapor is 5s to 15s.

[0010] In one embodiment, the purging conditions are: the temperature is controlled at 100° C. to 180° C., the flow rate of the water vapor is 5 sccm to 30 sccm, and the introduction time is 1 s to 5 s;

[0011] And / or, the number of times of purging is 2 to 5 times, and the interval time between two times of introducing the water vapor is 1 second to 5 seconds.

[0012] In one embodiment, the passivation layer at least includes an aluminum oxide layer, and the aluminum oxide layer is stacked on the surface of the silicon dioxide layer.

[0013] In one of the embodiments, the step of depositing an aluminum oxide layer on the surface of the silicon dioxide layer includes: controlling the deposition temperature to 250°C to 350°C, circulating trimethylaluminum and water vapor, wherein the flow rate of the trimethylaluminum is 10sccm to 30sccm, and the time for continuously introducing the trimethylaluminum is 5s to 15s, and the flow rate of the water vapor is 5sccm to 30sccm, and the time for continuously introducing the water vapor is 5s to 15s.

[0014] In one embodiment, the number of times the trimethylaluminum and the water vapor are circulated is 15 to 60 times.

[0015] According to a second aspect of the present invention, a solar cell front passivation layer obtained by a method for preparing a solar cell front passivation layer is provided, wherein a silicon dioxide layer is further sandwiched between the passivation layer and the emitter.

[0016] In one embodiment, the thickness of the silicon dioxide layer is 1 nm to 1.5 nm.

[0017] According to a third aspect of the present invention, a method for preparing a solar cell is provided, wherein the method for preparing a front passivation layer is selected from the above-mentioned method for preparing a front passivation layer of a solar cell.

[0018] According to a fourth aspect of the present invention, there is provided a solar cell obtained according to the above-mentioned method for preparing a solar cell.

[0019] In the preparation method of the front passivation layer of the solar cell provided by the present invention, water vapor is first used to purge and oxidize the emitter surface of the silicon wafer before depositing the passivation layer, which can not only remove impurities on the emitter surface, but also form a dense silicon dioxide layer on the emitter surface to repair surface defects, thereby effectively improving the conversion efficiency of the solar cell and significantly improving the EL pollution of the solar cell. DETAILED DESCRIPTION

[0020] In order to facilitate the understanding of the present invention, the present invention will be described in more detail below. However, it should be understood that the present invention can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the technical field of the terminology of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific implementation methods or embodiments and are not intended to limit the present invention.

[0022] According to a first aspect of the present invention, the present invention provides a method for preparing a front passivation layer of a solar cell, comprising the following steps:

[0023] Water vapor is introduced to purge and oxidize the emitter of the silicon wafer to obtain a silicon dioxide layer;

[0024] A passivation layer is deposited on the surface of the silicon dioxide layer.

[0025] Among them, in the process of forming the silicon dioxide layer, the conditions of water vapor oxidation are crucial. If a dense silicon dioxide layer cannot be obtained, even if a silicon dioxide layer is formed between the emitter and the passivation layer, it cannot enhance the passivation effect.

[0026] Therefore, the conditions for controlling the water vapor oxidation in the present invention are: controlling the temperature to be 300° C. to 400° C., the flow rate of water vapor to be 5 sccm to 30 sccm, the introduction time to be 5 s to 15 s, and introducing water vapor at least twice.

[0027] In the water vapor oxidation process of the present invention, due to proper control of conditions, water vapor can decompose to produce oxygen molecules, and the silicon atoms on the surface react with the oxygen molecules at high temperature to generate a silicon dioxide starting layer. Thereafter, the oxygen molecules can continue to react with the silicon atoms in the silicon dioxide starting layer. At the same time, the oxygen molecules can also diffuse through the silicon dioxide starting layer to reach the interface and react with the silicon atoms, thereby being able to simultaneously and rapidly increase the thickness and density of the silicon dioxide layer.

[0028] Therefore, the present invention uses water vapor to purge and oxidize the emitter surface of the silicon wafer before depositing the passivation layer, which can not only remove impurities on the emitter surface, but also form a dense silicon dioxide layer on the emitter surface to repair surface defects, thereby effectively improving the conversion efficiency of the solar cell and significantly improving the EL pollution of the solar cell.

[0029] Specifically, the temperature during the water vapor oxidation process can be selected from any value among 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, 360°C, 370°C, 380°C, 390°C, and 400°C, or a range between any two values; the flow rate of water vapor can be selected from any value among 5sccm, 10sccm, 15sccm, 20sccm, 25sccm, and 30sccm, or a range between any two values; the time for the introduction of water vapor can be selected from any value among 5s, 7s, 10s, 12s, and 15s, or a range between any two values.

[0030] In one embodiment, during the water vapor oxidation process, the number of times water vapor is introduced is preferably 10 to 15 times. Optionally, the interval between two introductions of water vapor is 5s to 15s, thereby effectively improving the density of the silicon dioxide layer.

[0031] In one embodiment, the purging conditions are preferably: controlling the temperature to 100°C to 180°C, the flow rate of water vapor to 5sccm to 30sccm, and the introduction time to 1s to 5s. This setting can not only effectively remove impurities on the emitter surface, but also form a silicon dioxide layer on the emitter surface.

[0032] Specifically, during the process of passing water vapor for purging, the purging temperature is selected from any value of 100°C, 120°C, 150°C, 160°C, 180°C, or a range between any two values; the water vapor flow rate is any value of 5sccm, 10sccm, 15sccm, 20sccm, 25sccm, 30sccm, or a range between any two values; the introduction time is selected from any value of 1s, 2s, 3s, 4s, 5s, or a range between any two values.

[0033] During the process of introducing water vapor for purging, the number of purging is not limited and can be 1 time, 2 times, 3 times, etc. Preferably, the number of purging is 2 to 5 times, and the purging effect is better. At the same time, the interval time between two introductions of water vapor is 1s to 5s, which can better improve the purging effect.

[0034] It is understood that the front passivation layer of the solar cell can be selected from aluminum oxide layer, silicon nitride layer, etc. In the present invention, it is preferred that the passivation layer at least includes an aluminum oxide layer, and the aluminum oxide layer is stacked on the surface of the silicon dioxide layer, which can achieve a better passivation effect.

[0035] The aluminum oxide layer may be deposited by a PECVD method or an ALD method, and the present invention preferably uses the ALD method.

[0036] Optionally, the step of depositing an aluminum oxide layer on the surface of the silicon dioxide layer includes: controlling the deposition temperature to 250°C to 350°C, circulating trimethylaluminum and water vapor, wherein the flow rate of the trimethylaluminum is 10sccm to 30sccm, and the time for continuously introducing the trimethylaluminum is 5s to 15s, and the flow rate of the water vapor is 5sccm to 30sccm, and the time for continuously introducing the water vapor is 5s to 15s.

[0037] There is no limit to the number of times trimethylaluminum and water vapor are introduced in a cycle, and it can be selected according to the thickness requirement. Firstly introducing trimethylaluminum and then introducing water vapor is regarded as one cycle. In the present invention, the number of cycles is preferably 15 to 60 times.

[0038] Therefore, in the present invention, by using the ALD method to deposit the aluminum oxide layer and regulating the relevant deposition process, the deposition process can be controlled at the atomic level, and the obtained aluminum oxide layer is denser, and then, in combination with the silicon dioxide layer, a better passivation effect can be achieved.

[0039] It can be understood that the front passivation layer of the present invention can also continue to deposit a silicon nitride layer on the surface of the aluminum oxide layer, and the present invention is not limited here.

[0040] According to a second aspect of the present invention, there is provided a solar cell front passivation layer obtained by the above-mentioned method for preparing a solar cell front passivation layer, wherein a silicon dioxide layer is further sandwiched between the passivation layer and the emitter.

[0041] In one embodiment, when the passivation layer includes at least an aluminum oxide layer, a silicon dioxide layer and an aluminum oxide layer are sequentially stacked on the surface of the emitter.

[0042] In one embodiment, the silicon dioxide layer has a thickness of 1 nm to 1.5 nm.

[0043] According to a third aspect of the present invention, a method for preparing a solar cell is provided, wherein the front passivation layer is prepared by the above-mentioned method for preparing the front passivation layer of a solar cell.

[0044] For example, in the preparation methods of TOPCon cells and PERC cells, the preparation method of the front passivation layer of a solar cell can be selected from the preparation method of the front passivation layer of the solar cell.

[0045] It should be noted that the present invention only optimizes the process of the front passivation layer, and the steps of texturing, diffusion, SE, back coating, screen printing and sintering of the solar cell can all select existing processes as needed.

[0046] As a specific implementation, when the method for preparing the front passivation layer of a solar cell of the present invention is applied to a TOPCon cell, the following steps may be specifically included:

[0047] (a) performing a texturing treatment on the surface of a crystalline silicon substrate to form a velvet surface, and cleaning the crystalline silicon substrate after texturing;

[0048] (b) performing boron diffusion on the cleaned silicon substrate to prepare a PN junction;

[0049] (c) Forming a selective emitter through SE and oxidation;

[0050] (d) Removing the edge and back BSG, PN junction edge isolation and back polishing by back etching;

[0051] (e) preparing a tunneling oxide layer and an amorphous silicon layer by LPCVD;

[0052] (f) crystallizing and doping the amorphous silicon layer to form P-doped Poly-Si;

[0053] (g) removing the edge and front PSG, Poly-Si, BSG and front and back edge isolation by front etching;

[0054] (h) preparing a front passivation layer by using the above-mentioned method for preparing a front passivation layer of a solar cell, including depositing an aluminum oxide layer on the surface of the silicon dioxide layer by using an ALD method and depositing a silicon nitride layer on the surface of the aluminum oxide layer by using PECVD;

[0055] (i) depositing a silicon nitride layer on the back side by PECVD;

[0056] (j) The front electrode and back electrode are formed on the front and back of the silicon wafer respectively by screen printing and sintering.

[0057] According to a fourth aspect of the present invention, a solar cell obtained according to the above-mentioned method for preparing a solar cell is provided, such as a TOPCon cell and a PERC cell, wherein a silicon dioxide layer is sandwiched between the emitter and the passivation layer in the TOPCon cell and the PERC cell provided by the present invention.

[0058] Hereinafter, the solar cell front passivation layer and the preparation method thereof, the solar cell and the preparation method thereof will be further described through the following specific embodiments.

[0059] Reference example:

[0060] In the existing production line, the semi-finished silicon wafers after Poly removal are placed into a micro-guiding cavity and an aluminum oxide layer is directly deposited on the emitter surface. The deposition process is as follows: first, trimethylaluminum is introduced at a flow rate of 10 sccm for 5 seconds, then water vapor is introduced at a flow rate of 5 sccm for 5 seconds, the temperature is 250°C, and the number of cycles is 15.

[0061] Example 1

[0062] The difference from the reference example is that the semi-finished silicon wafer after Poly removal is placed in a micro-conductor cavity, the temperature is controlled at 100°C, water vapor is introduced for purging, the flow rate is 5sccm, the introduction time is 1s, the number of purging is 2 times, and the time interval between the two introductions of water vapor is 5s.

[0063] The temperature in the micro-conductor cavity was controlled at 300° C., and water vapor was introduced for water vapor oxidation. The flow rate was 5 sccm, the introduction time was 5 s, the number of times of introducing water vapor was 10 times, and the time interval between two introductions of water vapor was 5 s.

[0064] The temperature inside the micro-conductor cavity was controlled at 250°C. Trimethylaluminum was first introduced at a flow rate of 10 sccm, and then water vapor was introduced at a flow rate of 5 sccm. The continuous introduction time of trimethylaluminum and water vapor was 5 s. The number of cycles of introducing trimethylaluminum and water vapor was 15 times.

[0065] In the solar cell prepared in this embodiment, a silicon dioxide layer with a thickness of 1 nm is sandwiched between the front aluminum oxide layer and the emitter.

[0066] Embodiment 2:

[0067] The difference from the reference example is that the semi-finished silicon wafer after de-Poly is placed in the micro-guiding cavity, the temperature is controlled at 180°C, water vapor is introduced for purging, the flow rate is 30sccm, the introduction time is 5s, the number of purging is 5 times, and the time interval between two introductions of water vapor is 1s;

[0068] The temperature in the micro-conductor cavity was controlled to be 400°C, and water vapor was introduced for water vapor oxidation at a flow rate of 30 sccm, an introduction time of 15 s, 15 times of introduction of water vapor, and a time interval of 15 s between two introductions of water vapor;

[0069] The temperature inside the micro-conductor cavity was controlled at 350°C. Trimethylaluminum was first introduced at a flow rate of 30 sccm, and then water vapor was introduced at a flow rate of 30 sccm. The continuous introduction time of trimethylaluminum and water vapor was 15 s, and the number of cycles of introducing trimethylaluminum and water vapor was 60 times.

[0070] In the solar cell prepared in this embodiment, a silicon dioxide layer with a thickness of 1.5 nm is sandwiched between the front aluminum oxide layer and the emitter.

[0071] Embodiment 3:

[0072] The difference from the reference example is that the semi-finished silicon wafer after de-Poly is placed in the micro-guiding cavity, the temperature is controlled at 160°C, water vapor is introduced for purging, the flow rate is 20 sccm, the introduction time is 3s, the number of purging is 3 times, and the time interval between two introductions of water vapor is 5s;

[0073] The temperature in the micro-conductor cavity was controlled to be 350°C, and water vapor was introduced for water vapor oxidation at a flow rate of 20 sccm, an introduction time of 10 s, and a number of times of introducing water vapor 10 times, with a time interval of 10 s between two introductions of water vapor;

[0074] The temperature inside the micro-conductor cavity was controlled at 300°C. Trimethylaluminum was first introduced at a flow rate of 20 sccm, and then water vapor was introduced at a flow rate of 20 sccm. The continuous introduction time of trimethylaluminum and water vapor was 10 s, and the number of times of introducing trimethylaluminum and water vapor was 40 times.

[0075] In the solar cell prepared in this embodiment, a silicon dioxide layer with a thickness of 1.3 nm is sandwiched between the front aluminum oxide layer and the emitter.

[0076] Embodiment 4:

[0077] The difference from the reference example is that the semi-finished silicon wafer after de-Poly is placed in the micro-guiding cavity, the temperature is controlled at 140°C, water vapor is introduced for purging, the flow rate is 10 sccm, the introduction time is 4 s, the number of purging is 4 times, and the time interval between two introductions of water vapor is 5 s;

[0078] The temperature in the micro-guiding chamber was controlled to be 320°C, and water vapor was introduced for water vapor oxidation, with a flow rate of 10 sccm, an introduction time of 8 s, 10 introductions of water vapor, and an interval of 8 s between two introductions of water vapor.

[0079] The temperature inside the micro-conductor cavity was controlled at 280°C. Trimethylaluminum was first introduced at a flow rate of 10 sccm, and then water vapor was introduced at a flow rate of 10 sccm. The continuous introduction time of trimethylaluminum and water vapor was 8 s. The number of cycles of introducing trimethylaluminum and water vapor was 30 times.

[0080] In the solar cell prepared in this embodiment, a silicon dioxide layer with a thickness of 1.2 nm is sandwiched between the front aluminum oxide layer and the emitter.

[0081] Embodiment 5:

[0082] The difference from the reference example is that the semi-finished silicon wafer after Poly removal is placed in the micro-conductor cavity, the temperature is controlled at 100°C, water vapor is introduced for purging, the flow rate is 5sccm, the introduction time is 1s, the number of purging is 1, and the time interval between two introductions of water vapor is 5s;

[0083] The temperature in the micro-conductor cavity was controlled at 300° C., and water vapor was introduced for water vapor oxidation. The flow rate was 5 sccm, the introduction time was 5 s, the number of times of introducing water vapor was 10 times, and the time interval between two introductions of water vapor was 5 s.

[0084] The temperature inside the micro-conductor cavity was controlled at 250°C. Trimethylaluminum was first introduced at a flow rate of 10 sccm, and then water vapor was introduced at a flow rate of 5 sccm. The continuous introduction time of trimethylaluminum and water vapor was 5 s. The number of cycles of introducing trimethylaluminum and water vapor was 15 times.

[0085] In the solar cell prepared in this embodiment, a silicon dioxide layer with a thickness of 1 nm is sandwiched between the front aluminum oxide layer and the emitter.

[0086] Embodiment 6:

[0087] The difference from the reference example is that the semi-finished silicon wafer after Poly removal is placed in the micro-guiding cavity, the temperature is controlled at 100°C, water vapor is introduced for purging, the flow rate is 5sccm, the introduction time is 1s, the number of purging is 6 times, and the time interval between two introductions of water vapor is 5s;

[0088] The temperature in the micro-conductor cavity was controlled at 300° C., and water vapor was introduced for water vapor oxidation. The flow rate was 5 sccm, the introduction time was 5 s, the number of times of introducing water vapor was 10 times, and the time interval between two introductions of water vapor was 5 s.

[0089] The temperature inside the micro-conductor cavity was controlled at 250°C. Trimethylaluminum was first introduced at a flow rate of 10 sccm, and then water vapor was introduced at a flow rate of 5 sccm. The continuous introduction time of trimethylaluminum and water vapor was 5 s. The number of cycles of introducing trimethylaluminum and water vapor was 15 times.

[0090] In the solar cell prepared in this embodiment, a silicon dioxide layer with a thickness of 1.5 nm is sandwiched between the front aluminum oxide layer and the emitter.

[0091] Comparative Example 1:

[0092] The difference from Example 1 is that the temperature of water vapor oxidation is 410°C.

[0093] In the solar cell prepared in this comparative example, a silicon dioxide layer with a thickness of 6 nm is sandwiched between the front aluminum oxide layer and the emitter.

[0094] Comparative Example 2:

[0095] The difference from Example 1 is that the temperature of water vapor oxidation is 290°C.

[0096] In the solar cell prepared in this comparative example, a silicon dioxide layer with a thickness of 0.9 nm is sandwiched between the front aluminum oxide layer and the emitter.

[0097] The performance test of the front aluminum oxide layer of the solar cell of the reference example, embodiments 1 to 6, and comparative examples 1 and 2 was performed, and the test contents were conversion efficiency and EL pollution ratio, wherein the test standard of conversion efficiency was the normal standard of the production line, and the test standard of EL pollution ratio was the normal standard of the production line. The test results are shown in Table 1:

[0098] Table 1

[0099]

[0100] From the test results of Examples 1 to 6 and the reference example in Table 1 above, it can be seen that the present invention uses water vapor to purge and oxidize the surface of the silicon wafer before preparing the passivation layer, which can not only remove impurities on the emitter surface, but also generate a silicon dioxide layer on the emitter surface of the silicon wafer to repair surface defects. The prepared solar cell front passivation layer also has a silicon dioxide layer sandwiched between the passivation layer and the emitter, which increases the conversion efficiency of the solar cell by more than 0.11% and reduces the EL pollution ratio by more than 0.5%.

[0101] According to the test results of Example 1 and Comparative Examples 1 and 2, it can be known that in Comparative Examples 1 and 2, when the temperature of water vapor oxidation is lower than 300°C or higher than 400°C, the conversion effect is not improved but reduced. This indicates that when the oxidation temperature is too high or too low during the water vapor oxidation process, a dense silicon dioxide layer cannot be generated, and the passivation effect cannot be enhanced, resulting in an insignificant improvement in conversion efficiency. The temperature of the present invention is controlled at 300°C to 400°C during the water vapor oxidation process. Compared with the silicon dioxide layer prepared at a water vapor oxidation temperature of less than 300°C or greater than 400°C, the density is higher and the conversion efficiency of the solar cell is also higher.

[0102] From the comparison between Example 1 and Example 5 and Example 6 in Table 1, it can be seen that the number of purging times during the water vapor purging process of Example 5 is less than that of Example 1, and the number of purging times during the water vapor purging process of Example 6 is greater than that of Example 1. From the data of the EL pollution ratio, it can be seen that the cleaning effects of Example 5 and Example 6 are not as good as those of Example 1, indicating that the number of water vapor purging plays an important role in reducing the EL pollution ratio. The present invention has a better purging effect by limiting the number of water vapor purging times to 2 to 5 times, and can achieve the control of the EL pollution ratio within 2.0%, and has a significant effect of removing impurities on the surface of the silicon wafer.

[0103] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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.

[0104] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing a front passivation layer of a solar cell, characterized in that: The following steps are involved: Water vapor is introduced to purge and oxidize the emitter of the silicon wafer to obtain a silicon dioxide layer; Depositing a passivation layer on the surface of the silicon dioxide layer; The conditions for water vapor oxidation are as follows: the temperature is controlled at 300° C. to 400° C., the flow rate of the water vapor is 5 sccm to 30 sccm, the introduction time is 5 s to 15 s, and the water vapor is introduced at least twice.

2. The method for preparing a front passivation layer of a solar cell according to claim 1, characterized in that: During the water vapor oxidation process, the water vapor is introduced 10 to 15 times; And / or, the interval between two times of introducing the water vapor is 5s to 15s.

3. The method for preparing a front passivation layer of a solar cell according to claim 1, characterized in that: The purge conditions are: the temperature is controlled at 100°C to 180°C, the flow rate of the water vapor is 5sccm to 30sccm, and the introduction time is 1s to 5s; And / or, the number of times of purging is 2 to 5 times, and the interval time between two times of introducing the water vapor is 1 second to 5 seconds.

4. The method for preparing a front passivation layer of a solar cell according to claim 1, characterized in that: The passivation layer at least includes an aluminum oxide layer, and the aluminum oxide layer is stacked on the surface of the silicon dioxide layer.

5. The method for preparing a front passivation layer of a solar cell according to claim 4, characterized in that: The step of depositing an aluminum oxide layer on the surface of the silicon dioxide layer includes: controlling the deposition temperature to 250°C to 350°C, circulating trimethylaluminum and water vapor, wherein the flow rate of the trimethylaluminum is 10sccm to 30sccm, the time for continuously introducing the trimethylaluminum is 5s to 15s, the flow rate of the water vapor is 5sccm to 30sccm, and the time for continuously introducing the water vapor is 5s to 15s.

6. The method for preparing a front passivation layer of a solar cell according to claim 5, characterized in that: The number of times of cyclically introducing the trimethylaluminum and the water vapor is 15 to 60 times.

7. A solar cell front passivation layer obtained by the preparation method according to any one of claims 1 to 6, characterized in that: A silicon dioxide layer is also sandwiched between the passivation layer and the emitter.

8. The solar cell front passivation layer according to claim 7, characterized in that: The thickness of the silicon dioxide layer is 1 nm to 1.5 nm.

9. A method for preparing a solar cell, characterized in that: The method for preparing the front passivation layer is selected from the method for preparing the front passivation layer of a solar cell according to any one of claims 1 to 6.

10. A solar cell obtained according to the method for preparing a solar cell according to claim 9.

Images