Heterojunction solar cell preparation method and heterojunction solar cell

Abstract

The application provides a heterojunction solar cell preparation method and a heterojunction solar cell. The heterojunction solar cell obtained by the heterojunction solar cell preparation method provided by the application has a low doping concentration of the first doped amorphous silicon inner layer, can reduce the amorphous silicon structure distortion caused by doping, is beneficial to improving the passivation effect of the solar cell and improving the open circuit voltage; the setting of the doped amorphous silicon oxide layer can increase the optical band gap of the main light-receiving surface of the heterojunction solar cell, reduce the absorption of incident light in the passivation film layer, and improve the short circuit current of the solar cell; the first doped amorphous silicon outer layer has a high doping concentration, can reduce the contact resistance between the first doped amorphous silicon outer layer and the first transparent conductive film, and further reduce the series resistance of the solar cell, thereby effectively improving the photoelectric conversion efficiency of the heterojunction solar cell.

Description

Technical Field

[0001] This invention relates to the field of photovoltaics, and more particularly to a method for preparing a heterojunction solar cell and the heterojunction solar cell itself. Background Technology

[0002] With the development of the photovoltaic industry, the conversion efficiency of solar cells is increasing. Heterojunction solar cells, as one of the development directions of high-efficiency cells, combine the characteristics of crystalline silicon cells and silicon-based thin-film cells, possessing advantages such as short manufacturing processes, low processing temperatures, high conversion efficiency, and high power generation, thus accounting for an increasingly larger share of the industry. For heterojunction solar cells, the passivation film layer on the silicon substrate surface (usually including intrinsic passivation film and doped passivation film) can passivate the silicon substrate surface, greatly reducing the surface recombination rate. Furthermore, the larger band gap width, after forming a PN junction with crystalline silicon, can obtain a larger built-in electric field, resulting in a higher open-circuit voltage for heterojunction cells. The passivation film is often composed of amorphous silicon film layers (including intrinsic amorphous silicon film and doped amorphous silicon film). Amorphous silicon itself has a high light absorption coefficient, resulting in significant absorption of incident light, leading to a reduction in the number of photons actually incident into the silicon substrate, affecting the number of photogenerated carriers; consequently, this leads to a decrease in the short-circuit current of the heterojunction solar cell, affecting its photoelectric conversion efficiency.

[0003] In the existing technology, there is a technique of using oxygen-containing gas doping to dope the amorphous silicon film on the main light-receiving surface to form doped amorphous silicon oxide with better light transmittance. This method can effectively increase the optical band gap of the passivation film, increase light transmission, and reduce light absorption in the film. However, the transformation of amorphous silicon into silicon oxide will lead to an increase in the film transmission resistance, which will affect the series resistance of the solar cell and ultimately affect the photoelectric conversion efficiency of the heterojunction cell.

[0004] In view of this, it is necessary to provide an improved technical solution to solve the above problems. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. In order to achieve the above-mentioned objective, the present invention provides a method for fabricating a heterojunction solar cell, the specific design of which is as follows.

[0006] A method for fabricating a heterojunction solar cell includes sequentially fabricating a first intrinsic passivation film, a first doped passivation film, and a first transparent conductive film on the main light-receiving side of a silicon substrate. The fabrication of the first doped passivation film includes the following steps: depositing a first doped amorphous silicon inner layer; depositing a doped amorphous silicon oxide layer; and depositing a first doped amorphous silicon outer layer, wherein the doping element concentration during the deposition of the first doped amorphous silicon outer layer is greater than the doping element concentration during the deposition of the first doped amorphous silicon inner layer.

[0007] Furthermore, when depositing the first doped amorphous silicon inner layer and the first doped amorphous silicon outer layer, SiH4 gas, H2 gas, and phosphorus-containing gas are introduced. The flow rate ratio of SiH4 gas to phosphorus-containing gas is greater when depositing the first doped amorphous silicon inner layer than when depositing the first doped amorphous silicon outer layer.

[0008] Furthermore, the phosphorus-containing gas includes PH3 and H2 carrier gas, and the volume content of PH3 relative to H2 carrier gas is 1%.

[0009] Furthermore, when depositing the first doped amorphous silicon inner layer, the flow rate ratio of SiH4 gas to H2 gas ranges from 1:5 to 1:15, the flow rate ratio of SiH4 gas to phosphorus-containing gas ranges from 5:1 to 1:3, and the flow rate of SiH4 gas ranges from 100 to 600 sccm; when depositing the first doped amorphous silicon outer layer, the flow rate ratio of SiH4 gas to H2 gas ranges from 5:1 to 1:3, the flow rate ratio of SiH4 gas to phosphorus-containing gas ranges from 1:3 to 1:10, and the flow rate of SiH4 gas ranges from 100 to 600 sccm.

[0010] Furthermore, when depositing the first doped amorphous silicon inner layer and the first doped amorphous silicon outer layer, the radio frequency power range is 150-700W, and the deposition rate range is 0.05nm / s-0.3nm / s.

[0011] Furthermore, the thickness range of the first doped amorphous silicon inner layer and the first doped amorphous silicon outer layer is 1-3 nm.

[0012] Furthermore, during the deposition of the doped amorphous silicon oxide layer, SiH4 gas, H2 gas, phosphorus-containing gas, and CO2 gas are introduced, wherein the phosphorus-containing gas includes PH3 and H2 carrier gas, and the volume content of PH3 relative to H2 carrier gas is 1%; during the deposition process, the flow rate ratio of SiH4 gas to H2 gas is in the range of 1:3-1:10, the flow rate ratio of SiH4 gas to phosphorus-containing gas is in the range of 1:3-1:10, the flow rate ratio of SiH4 gas to CO2 gas is in the range of 3:1-1:5, and the flow rate of SiH4 gas is in the range of 100-600 sccm.

[0013] Furthermore, when depositing the doped amorphous silicon oxide layer, the radio frequency power ranges from 300 to 1000 W, the deposition rate ranges from 0.05 nm / s to 0.3 nm / s, and the thickness ranges from 2 to 6 nm.

[0014] Further, the fabrication of the first intrinsic passivation film includes the following steps: depositing a first intrinsic amorphous silicon inner layer using SiH4 gas at a first deposition rate; depositing a first intrinsic amorphous silicon outer layer using SiH4 gas and H2 gas at a second deposition rate, wherein the second deposition rate is less than the first deposition rate; and performing plasma treatment using H2 to etch at least a portion of the first intrinsic amorphous silicon outer layer and increase the hydrogen content of the first intrinsic passivation film.

[0015] Furthermore, the preparation method further includes: fabricating a front electrode on the surface of the first transparent conductive film; and sequentially fabricating a second intrinsic passivation film, a second doped passivation film, a second transparent conductive film, and a back electrode on the secondary light-receiving side of the silicon substrate.

[0016] The present invention also provides a heterojunction solar cell, which is prepared by the heterojunction solar cell preparation method described above.

[0017] The beneficial effects of this invention are as follows: Based on the heterojunction solar cell fabrication method provided by this invention, the obtained heterojunction solar cell structure has a low doping concentration in the first doped amorphous silicon inner layer, which can reduce the amorphous silicon structure distortion caused by doping. When in contact with the first intrinsic passivation film, there is no significant structural difference, which acts as a buffer layer between the first intrinsic passivation film and the high-concentration doped first doped amorphous silicon outer layer, which is beneficial to improving the passivation effect of the solar cell and increasing the open-circuit voltage. The setting of the doped amorphous silicon oxide layer can increase the optical bandgap of the main light-receiving surface of the heterojunction solar cell, reduce the absorption of incident light in the passivation film layer, and increase the short-circuit current of the solar cell. The high doping concentration of the first doped amorphous silicon outer layer can reduce the contact resistance between it and the first transparent conductive film, thereby reducing the series resistance of the solar cell and effectively improving the photoelectric conversion efficiency of the heterojunction cell. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0019] Figure 1 The image shows a cross-sectional schematic diagram of a heterojunction solar cell. Detailed Implementation

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

[0021] In this invention, the side of a solar cell that faces the sun and directly receives sunlight is called the light-receiving side, and the other side opposite the light-receiving side is called the back-lighting side. Considering that the back of a bifacial cell also receives sunlight, the light-receiving side is called the primary light-receiving side, and the back-lighting side is called the secondary light-receiving side.

[0022] Combination Figure 1 As shown, the method for fabricating a heterojunction solar cell according to the present invention includes sequentially fabricating a first intrinsic passivation film 21, a first doped passivation film 31, and a first transparent conductive film 41 on the main light-receiving surface of a silicon substrate 100.

[0023] Specifically, the fabrication of the first doped passivation film 31 includes the following steps: depositing a first doped amorphous silicon inner layer 311; depositing a doped amorphous silicon oxide layer 312; and depositing a first doped amorphous silicon outer layer 313, wherein the doping element concentration during the deposition of the first doped amorphous silicon outer layer 313 is greater than the doping element concentration during the deposition of the first doped amorphous silicon inner layer 311.

[0024] Based on the heterojunction solar cell fabrication method provided by this invention, the obtained heterojunction solar cell structure has a low doping concentration in the first doped amorphous silicon inner layer 311, which reduces the amorphous silicon structure distortion caused by doping. When in contact with the first intrinsic passivation film 21, there is no significant structural difference. It can act as a buffer layer between the first intrinsic passivation film 21 and the highly doped first doped amorphous silicon outer layer 313, which is beneficial for improving the passivation effect and increasing the open-circuit voltage of the solar cell. The doped amorphous silicon oxide layer 312 increases the optical bandgap of the main light-receiving surface of the heterojunction solar cell, reduces the absorption of incident light in the passivation film layer, and increases the short-circuit current of the solar cell. The high doping concentration of the first doped amorphous silicon outer layer 313 reduces its contact resistance with the first transparent conductive film 41, thereby reducing the series resistance of the solar cell and effectively improving the photoelectric conversion efficiency of the heterojunction cell.

[0025] More specific implementation parameters of the heterojunction solar cell fabrication method involved in this invention are described below:

[0026] In some embodiments, when depositing the first doped amorphous silicon inner layer 311 and the first doped amorphous silicon outer layer 313, SiH4 gas, H2 gas, and phosphorus-containing gas are introduced. The flow rate ratio of SiH4 gas to phosphorus-containing gas during the deposition of the first doped amorphous silicon inner layer 311 is greater than that during the deposition of the first doped amorphous silicon outer layer 313. It is easily understood that in this embodiment, the doping element involved in the first doped passivation film 31 is phosphorus. In specific implementation, the flow rate ratio of phosphorus-containing gas during the deposition of the first doped amorphous silicon inner layer 311 is less than that during the deposition of the first doped amorphous silicon outer layer 313, which allows the doping concentration of the first doped amorphous silicon inner layer 311 to be lower than that of the first doped amorphous silicon outer layer 313.

[0027] In some specific embodiments of the present invention, the phosphorus-containing gas involved includes PH3 and H2 carrier gas, and the volume content of PH3 relative to H2 carrier gas is 1%.

[0028] In the specific implementation process, when depositing the first doped amorphous silicon inner layer 311, the flow rate ratio of SiH4 gas to H2 gas ranges from 1:5 to 1:15, the flow rate ratio of SiH4 gas to phosphorus-containing gas ranges from 5:1 to 1:3, and the flow rate of SiH4 gas ranges from 100 to 600 sccm. When depositing the first doped amorphous silicon outer layer 313, the flow rate ratio of SiH4 gas to H2 gas ranges from 5:1 to 1:3, the flow rate ratio of SiH4 gas to phosphorus-containing gas ranges from 1:3 to 1:10, and the flow rate of SiH4 gas ranges from 100 to 600 sccm.

[0029] Furthermore, when depositing the first doped amorphous silicon inner layer 311 and the first doped amorphous silicon outer layer 313, the RF power range is 150-700W, and the deposition rate range is 0.05nm / s-0.3nm / s.

[0030] Preferably, the thickness range of the first doped amorphous silicon inner layer 311 and the first doped amorphous silicon outer layer 313 is 1-3 nm.

[0031] In other embodiments of the present invention, during the deposition of the doped amorphous silicon oxide layer 312, SiH4 gas, H2 gas, phosphorus-containing gas, and CO2 gas are introduced, wherein the phosphorus-containing gas includes PH3 and H2 carrier gas, and the volume content of PH3 relative to H2 carrier gas is 1%. During the deposition of the doped amorphous silicon oxide layer 312, the flow rate ratio of SiH4 gas to H2 gas ranges from 1:3 to 1:10, the flow rate ratio of SiH4 gas to phosphorus-containing gas ranges from 1:3 to 1:10, the flow rate ratio of SiH4 gas to CO2 gas ranges from 3:1 to 1:5, and the flow rate of SiH4 gas ranges from 100 to 600 sccm.

[0032] Furthermore, when depositing the doped amorphous silicon oxide layer 312, the RF power range is 300-1000W, the deposition rate range is 0.05nm / s-0.3nm / s, and the thickness range is 2-6nm.

[0033] In one more specific embodiment: when depositing the first doped amorphous silicon inner layer 311, the flow rates of SiH4 gas, H2 gas, and phosphorus-containing gas are 300 sccm, 1500 sccm, and 300 sccm, respectively; the RF power is 300 W; the deposition rate is 0.1 nm / s; and the thickness is 1.5 nm. When depositing the doped amorphous silicon oxide layer 312, the flow rates of SiH4 gas, H2 gas, phosphorus-containing gas, and CO2 gas are 300 sccm, 900 sccm, 900 sccm, and 150 sccm, respectively; the RF power is 600 W; the deposition rate is 0.12 nm / s; and the thickness is 4 nm. When depositing the first doped amorphous silicon outer layer 313, the flow rates of SiH4 gas, H2 gas, and phosphorus-containing gas are 300 sccm, 300 sccm, and 1500 sccm, respectively; the RF power is 300 W; the deposition rate is 0.1 nm / s; and the thickness is 1.5 nm.

[0034] In some preferred embodiments of the present invention, during the deposition of the first doped amorphous silicon inner layer 311 and the first doped amorphous silicon outer layer 313, the ratio of the SiH4 gas flow rate to the total hydrogen flow rate (including H2 gas and H2 carrier gas in the phosphorus-containing gas) is consistent. As in the above embodiments, during the deposition of the first doped amorphous silicon inner layer 311 and the first doped amorphous silicon outer layer 313, the SiH4 gas flow rate is 300 sccm, and the total hydrogen flow rate is 1800 sccm (the volume content of PH3 relative to the H2 carrier gas is 1%, which can be ignored in the flow rate calculation).

[0035] In some other embodiments of the invention, reference is made to Figure 1 As shown, the fabrication of the first intrinsic passivation film 21 includes the following steps: depositing a first intrinsic amorphous silicon inner layer 211 using SiH4 gas at a first deposition rate; depositing a first intrinsic amorphous silicon outer layer 212 using SiH4 gas and H2 gas at a second deposition rate, wherein the second deposition rate is less than the first deposition rate; and performing plasma treatment using H2 to etch at least a portion of the first intrinsic amorphous silicon outer layer 212 and increase the hydrogen content of the first intrinsic passivation film 21.

[0036] In this embodiment, the first intrinsic amorphous silicon inner layer 211 adopts a relatively high deposition rate, which can effectively suppress the epitaxial growth of amorphous silicon on the surface of silicon substrate 100. Meanwhile, the first intrinsic amorphous silicon outer layer 212 adopts a relatively low deposition rate, which can improve the deposition quality of amorphous silicon and enhance the passivation effect.

[0037] More specifically, when depositing the first intrinsic amorphous silicon inner layer 211, the radio frequency power range is 400-1000W, and SiH4 gas is used, with a SiH4 gas flow rate range of 500-2000 sccm; when depositing the first intrinsic amorphous silicon outer layer 212, the radio frequency power range is 150W-400W, and a SiH4 / H2 mixed gas is used, with the SiH4 to H2 flow rate ratio in the SiH4 / H2 mixed gas ranging from 5:1 to 1:20, wherein the SiH4 gas flow rate range is 100-800 sccm.

[0038] The deposition rate of the first intrinsic amorphous silicon inner layer 211 ranges from 0.4 nm / s to 1.2 nm / s, and the deposition rate of the first intrinsic amorphous silicon outer layer 212 ranges from 0.03 nm / s to 0.3 nm / s. The thickness of the first intrinsic amorphous silicon inner layer 211 is less than the thickness of the first intrinsic amorphous silicon outer layer 212, wherein the thickness of the first intrinsic amorphous silicon inner layer 211 ranges from 1 nm to 3 nm, and the thickness of the first intrinsic amorphous silicon outer layer 212 ranges from 2 nm to 6 nm.

[0039] In this invention, when using H2 for plasma treatment, the radio frequency power ranges from 1500 to 3000 W, and the H2 flow rate ranges from 1000 to 3000 sccm. The main purpose of using H2 for plasma treatment in this invention is to increase the hydrogen content in the first intrinsic passivation film 21. At the same time, when etching the first intrinsic amorphous silicon outer layer 212, some loosely structured structures are preferentially etched, resulting in a more dense film surface. This provides a certain degree of resistance to the intrusion of dopant elements into the first intrinsic passivation film 21 during the subsequent deposition of the first doped passivation film 31.

[0040] In this invention, the pressure range is controlled to be 0.5-0.7 torr when forming the first intrinsic passivation film 21.

[0041] In one specific embodiment, when depositing the first intrinsic amorphous silicon inner layer 211, the deposition rate is 0.6 nm / s, the SiH4 gas flow rate is 1000 sccm, the RF power is 600 W, and the thickness is 1.5 nm. When depositing the first intrinsic amorphous silicon outer layer 212, the deposition rate is 0.15 nm / s, the SiH4 to H2 flow rate ratio is 1:1, the SiH4 gas flow rate is 500 sccm, the RF power is 300 W, and the thickness is 2 nm.

[0042] Furthermore, the preparation method also includes: fabricating a front electrode 51 on the surface of the first transparent conductive film 41; and sequentially fabricating a second intrinsic passivation film 22, a second doped passivation film 32, a second transparent conductive film 42, and a back electrode 52 on one side of the bottom light-receiving surface of the silicon substrate 100.

[0043] The second intrinsic passivation film 22 can be manufactured using existing manufacturing processes, or it can be manufactured using the following processes, as described in detail below.

[0044] The forming process of the second intrinsic passivation film 22 includes: sequentially depositing a second intrinsic amorphous silicon inner layer 221 and a second intrinsic amorphous silicon outer layer 222 on the secondary light-receiving side of the silicon substrate 100. The forming process of the second intrinsic amorphous silicon inner layer 221 can refer to the forming process of the first intrinsic amorphous silicon inner layer 2111, and the forming process of the second intrinsic amorphous silicon outer layer 222 can refer to the forming process of the first intrinsic amorphous silicon outer layer 2112. The difference from the first intrinsic amorphous silicon layer 211 is that the thickness of the second intrinsic amorphous silicon inner layer 221 ranges from 1 nm to 3 nm, the thickness of the second intrinsic amorphous silicon outer layer 222 ranges from 4 nm to 8 nm, and the thickness of the second intrinsic passivation film 22 is not less than 7 nm.

[0045] In this invention, the second doped passivation film 32 is preferably deposited using a gradient doping method. Specifically, a low concentration of doping is used on the side where the second doped passivation film 32 intersects with the second intrinsic passivation film 22, and a high concentration of doping is used on the side where it intersects with the second transparent conductive film 42. The first doped passivation film 31 and the second doped passivation film 32 can be a bilayer film structure or a multilayer gradient film structure.

[0046] When forming the second doped passivation film 32, SiH4 gas, H2 gas, and boron-containing gas are introduced. The boron-containing gas involved includes B2H6 and H2 carrier gas, and the volume content of B2H6 relative to H2 carrier gas is 2%.

[0047] In the specific implementation process, during the fabrication of the second doped passivation film 32, the flow ratio of SiH4 to B2H6 on the low-concentration doped side is in the range of 5:1 to 1:3, and the flow ratio of SiH4 to B2H6 on the high-concentration doped side is in the range of 1:1 to 1:6.

[0048] In a preferred embodiment of the present invention, the silicon substrate 100 involved is an N-type silicon wafer, the surface of which typically needs to be texturized before the deposition of various film layers. The main light-receiving surface of the silicon substrate 100 is N-type doped, and the secondary light-receiving surface is P-type doped, that is, the first doped passivation film 31 is an N-type doped film, and the second doped passivation film 32 is a P-type doped film.

[0049] More preferably, the thickness of the second doped passivation film 32 ranges from 4 to 10 nm, wherein the thickness of the low doping concentration portion ranges from 1 to 4 nm, and the thickness of the high doping concentration portion is not less than the thickness of the low doping concentration portion.

[0050] The first transparent conductive film 41 and the second transparent conductive film 42 involved in this invention are typically TCO films, such as ITO films.

[0051] The front electrode 51 and the back electrode 52 are typically silver electrodes.

[0052] The present invention also provides a heterojunction solar cell, which is prepared by the above-described heterojunction solar cell preparation method.

[0053] It should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0054] The detailed descriptions listed above are merely specific descriptions of feasible embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. All equivalent embodiments or modifications made without departing from the spirit of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for fabricating a heterojunction solar cell, comprising sequentially fabricating a first intrinsic passivation film, a first doped passivation film, and a first transparent conductive film on one side of the main light-receiving surface of a silicon substrate, characterized in that, The fabrication of the first doped passivation film includes the following steps: depositing a first doped amorphous silicon inner layer; depositing a doped amorphous silicon oxide layer; depositing a first doped amorphous silicon outer layer, wherein the doping element concentration during the deposition of the first doped amorphous silicon outer layer is greater than the doping element concentration during the deposition of the first doped amorphous silicon inner layer; during the deposition of both the first doped amorphous silicon inner layer and the first doped amorphous silicon outer layer, SiH4 gas, H2 gas, and phosphorus-containing gas are introduced, wherein the flow rate ratio of SiH4 gas to phosphorus-containing gas during the deposition of the first doped amorphous silicon inner layer is greater than the flow rate ratio of SiH4 gas to phosphorus-containing gas during the deposition of the first doped amorphous silicon outer layer; the phosphorus-containing gas includes PH3 and H2 carrier gas, and the volume content of PH3 relative to H2 carrier gas is 1%; the thickness range of both the first doped amorphous silicon inner layer and the first doped amorphous silicon outer layer is 1-3 nm.

2. The method for fabricating a heterojunction solar cell according to claim 1, characterized in that, When depositing the first doped amorphous silicon inner layer, the flow rate ratio of SiH4 gas to H2 gas ranges from 1:5 to 1:15, the flow rate ratio of SiH4 gas to phosphorus-containing gas ranges from 5:1 to 1:3, and the flow rate of SiH4 gas ranges from 100 to 600 sccm; when depositing the first doped amorphous silicon outer layer, the flow rate ratio of SiH4 gas to H2 gas ranges from 5:1 to 1:3, the flow rate ratio of SiH4 gas to phosphorus-containing gas ranges from 1:3 to 1:10, and the flow rate of SiH4 gas ranges from 100 to 600 sccm.

3. The method for fabricating a heterojunction solar cell according to claim 2, characterized in that, When depositing the first doped amorphous silicon inner layer and the first doped amorphous silicon outer layer, the radio frequency power range is 150-700W, and the deposition rate range is 0.05nm / s-0.3nm / s.

4. The method for fabricating a heterojunction solar cell according to claim 3, characterized in that, The thickness of both the first doped amorphous silicon inner layer and the first doped amorphous silicon outer layer is 1.5 nm.

5. The method for fabricating a heterojunction solar cell according to any one of claims 1-4, characterized in that, During the deposition of the doped amorphous silicon oxide layer, SiH4 gas, H2 gas, phosphorus-containing gas, and CO2 gas are introduced. The phosphorus-containing gas includes PH3 and H2 carrier gas, and the volume content of PH3 relative to H2 carrier gas is 1%. During the deposition process, the flow rate ratio of SiH4 gas to H2 gas is in the range of 1:3-1:10, the flow rate ratio of SiH4 gas to phosphorus-containing gas is in the range of 1:3-1:10, the flow rate ratio of SiH4 gas to CO2 gas is in the range of 3:1-1:5, and the flow rate of SiH4 gas is in the range of 100-600 sccm.

6. The method for fabricating a heterojunction solar cell according to claim 5, characterized in that, When depositing the doped amorphous silicon oxide layer, the radio frequency power ranges from 300 to 1000 W, the deposition rate ranges from 0.05 nm / s to 0.3 nm / s, and the thickness ranges from 2 to 6 nm.

7. The method for fabricating a heterojunction solar cell according to any one of claims 1-4, characterized in that, The fabrication of the first intrinsic passivation film includes the following steps: depositing a first intrinsic amorphous silicon inner layer using SiH4 gas at a first deposition rate; depositing a first intrinsic amorphous silicon outer layer using SiH4 gas and H2 gas at a second deposition rate, wherein the second deposition rate is less than the first deposition rate; and performing plasma treatment using H2 to etch at least a portion of the first intrinsic amorphous silicon outer layer and increase the hydrogen content of the first intrinsic passivation film.

8. The method for fabricating a heterojunction solar cell according to claim 1, characterized in that, The preparation method further includes: A front electrode is fabricated on the surface of the first transparent conductive film; A second intrinsic passivation film, a second doped passivation film, a second transparent conductive film, and a back electrode are sequentially fabricated on the secondary light-receiving side of the silicon substrate.

9. A heterojunction solar cell, characterized in that, It is prepared by the method for preparing heterojunction solar cells according to any one of claims 1-8.

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