Preparation method of heterojunction solar cell and heterojunction solar cell

Abstract

The invention provides a preparation method of a heterojunction solar cell and the heterojunction solar cell, and relates to the technical field of solar cell preparation. The preparation method of the heterojunction solar cell comprises the steps that a first passivation layer and a second passivation layer located on the first passivation layer are deposited on the first surface of a substrate; a third passivation layer and a fourth passivation layer on the third passivation layer are deposited on the second surface of the substrate. A first passivation layer and a third passivation layer are deposited under a first reaction condition, a second passivation layer and a fourth passivation layer are prepared under a second reaction condition, and the process parameters of the first reaction condition and the second reaction condition are different. According to the method, the process parameters of the first reaction condition and the second reaction condition are different, so that the prepared first passivation layer, the prepared second passivation layer, the prepared third passivation layer and the prepared fourth passivation layer which are positioned on the same side of the substrate have different performances; and therefore, the epitaxial prevention and passivation effects of the passivation layer of the solar cell can be met.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cell preparation, and in particular to a preparation method of a heterojunction solar cell and a heterojunction solar cell. Background Art

[0002] The existing heterojunction solar cell passivation layer structure is usually composed of a thin layer of intrinsic amorphous silicon layer that prevents the epitaxial growth of silicon crystals and at least one layer of intrinsic amorphous silicon layer that mainly plays a passivation role. In the prior art, for the intrinsic amorphous silicon layer that mainly plays a passivation role, the deposition coating is usually carried out under the conditions of lower gas pressure and lower deposition rate. At the same time, the intrinsic amorphous silicon layer deposited under a lower hydrogen flow rate has a denser structure, which is not conducive to the subsequent microcrystalline growth of the doped layer, thereby limiting the carrier transmission performance and reducing the conversion efficiency of the heterojunction solar cell. There is also a prior art that uses a higher pressure to prepare the intrinsic amorphous silicon layer that mainly plays a passivation role, but due to the excessive pressure, the passivation effect of the prepared film layer is poor, which ultimately limits the improvement of the conversion efficiency of the solar cell. Summary of the invention

[0003] An object of the first aspect of the present invention is to provide a method for preparing a heterojunction solar cell, so as to solve the problem in the prior art that the passivation effect of the intrinsic amorphous silicon layer and the growth of the doped layer are contradictory and cannot be improved at the same time.

[0004] Another object of the first aspect of the present invention is to solve the problem that the intrinsic amorphous silicon layer that prevents epitaxy in the prior art has a poor anti-epitaxial effect.

[0005] A second aspect of the present invention aims to provide a heterojunction solar cell.

[0006] In particular, the present invention also provides a method for preparing a heterojunction solar cell, comprising:

[0007] depositing a first passivation layer and a second passivation layer on the first passivation layer on the first surface of the substrate;

[0008] depositing a third passivation layer and a fourth passivation layer on the third passivation layer on the second surface of the substrate;

[0009] Depositing a first doping layer and a second doping layer on the second passivation layer and the fourth passivation layer, respectively;

[0010] depositing a first transparent conductive layer and a second transparent conductive layer on the first doped layer and the second doped layer respectively;

[0011] A first electrode and a second electrode are prepared on the first transparent conductive layer and the second transparent conductive layer; wherein,

[0012] Depositing a first passivation layer and a third passivation layer under a first reaction condition, and preparing a second passivation layer and a fourth passivation layer under a second reaction condition, wherein the process parameters of the first reaction condition and the second reaction condition are different; or

[0013] The second passivation layer includes a second passivation inner layer and a second passivation outer layer, and the fourth passivation layer includes a fourth passivation inner layer and a fourth passivation outer layer;

[0014] The first passivation layer and the third passivation layer are deposited under the first reaction condition, and the second passivation outer layer and the fourth passivation outer layer are prepared under the second reaction condition, wherein the process parameters of the first reaction condition and the second reaction condition are different.

[0015] Optionally, the pressure in the first reaction condition is lower than the pressure in the second reaction condition, and the power density in the first reaction condition is lower than the power density in the second reaction condition.

[0016] Optionally, the pressure in the first reaction condition is 0.4-0.8 torr, and the power density is 30-50 mW / cm 2 The pressure of the second reaction condition is 1.5 to 2.1 torr, and the power density is 35 to 70 mW / cm 2 .

[0017] Optionally, the second passivation inner layer and the fourth passivation inner layer are deposited under third reaction conditions, and the hydrogen flow rate in the third reaction conditions is less than the hydrogen flow rate in the second reaction conditions.

[0018] Optionally, in the first reaction condition, the frequency is 13.56 MHz, the deposition chamber temperature is 150° C. to 230° C., and the silane flow rate is 400 to 800 sccm.

[0019] Optionally, the pressure of the second reaction condition is greater than or equal to the pressure of the third reaction condition.

[0020] Optionally, the first passivation layer, the second passivation layer, the third passivation layer and the fourth passivation layer are all intrinsic amorphous silicon.

[0021] Optionally, under the first reaction condition, the hydrogen flow rate is 0 sccm.

[0022] Optionally, the thickness of the first passivation layer and the third passivation layer is 1.5-2.5 nm, and the thickness of the second passivation layer and the fourth passivation layer is 4-8 nm.

[0023] In particular, the present invention also provides a heterojunction solar cell, which is prepared using the above-mentioned preparation method.

[0024] The reaction conditions of the first passivation layer and the third passivation layer in this scheme are both the first reaction conditions. The reaction conditions of the second passivation layer and the fourth passivation layer are both the second reaction conditions. However, the process parameters of the first reaction condition and the second reaction condition are different, so that the first passivation layer and the second passivation layer prepared on the same side of the substrate can have different properties, and the third passivation layer and the fourth passivation layer on the other side of the substrate have different properties, thereby satisfying the anti-epitaxial and passivation effects of the passivation layer of the solar cell.

[0025] The second reaction condition of this scheme has a higher pressure, a higher power density and a higher hydrogen flow rate. Therefore, the second passivation layer or the fourth passivation layer prepared using the second reaction condition has a better passivation effect, and is conducive to the subsequent growth of microcrystalline silicon, thereby improving the crystallization rate of the microcrystalline silicon layer and thus improving the efficiency of the battery.

[0026] In this scheme, when preparing the second passivation outer layer and the fourth passivation outer layer, there is a high hydrogen flow rate, so the hydrogen will have a strong bombardment effect on the bottom layer, so the second passivation inner layer is set between the first passivation layer and the second passivation outer layer, and the fourth passivation inner layer is set between the third passivation layer and the fourth passivation outer layer, and the reaction conditions for preparing the second passivation inner layer and the fourth passivation inner layer are both the third conditions, and the hydrogen flow rate in the third reaction condition is less than the hydrogen flow rate in the second reaction condition. In this way, the hydrogen flow rate can be reduced when preparing the second passivation inner layer and the fourth passivation inner layer, the bombardment on the first passivation layer is small, and the damage to the first passivation layer and the third passivation layer is reduced, and the anti-epitaxial effect of the first passivation layer and the third passivation layer is not affected.

[0027] The hydrogen flow rate, power density and pressure in the third reaction condition of this scheme are all less than or equal to the hydrogen flow rate, power density and pressure in the second reaction condition. In this way, the performance of the second passivation inner layer and the fourth passivation inner layer in the third reaction condition is reduced in terms of their auxiliary effect on subsequent microcrystal growth compared to the second passivation outer layer and the fourth passivation outer layer prepared by the second reaction condition, and their ability to improve the crystallization rate is relatively weakened. However, since the second passivation outer layer is arranged outside the second passivation inner layer and the fourth passivation outer layer is arranged outside the fourth passivation inner layer, the properties of the inner layer and the outer layer are combined, which reduces the bombardment damage to the first passivation layer and the third passivation layer, while improving the crystallinity of the microcrystal doping layer, thereby improving the battery conversion effect.

[0028] Based on the following detailed description of specific embodiments of the present invention in conjunction with the accompanying drawings, those skilled in the art will become more aware of the above and other objects, advantages and features of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Hereinafter, some specific embodiments of the present invention will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings:

[0030] Figure 1 is a schematic diagram of the structure of a preparation process of a heterojunction solar cell according to a specific embodiment of the present invention;

[0031] Figure 2 is a schematic diagram of the structure of a preparation process of a heterojunction solar cell according to another specific embodiment of the present invention;

[0032] Figure 3 (a) is a comparison chart of the conversion efficiency of heterojunction solar cells prepared according to Example 1, Example 2 and the comparative example of the present invention;

[0033] Figure 3 (b) is a comparison chart of the filling factors of heterojunction solar cells prepared according to Example 1, Example 2 and the comparative example of the present invention;

[0034] Figure 3 (c) is a comparison chart of the open circuit voltages of heterojunction solar cells prepared according to Example 1, Example 2 and the comparative example of the present invention;

[0035] Figure 3 (d) is a comparison chart of the series resistance of heterojunction solar cells prepared according to Example 1, Example 2 and the comparative example of the present invention.

[0036] Explanation of the accompanying drawings: substrate-100; first passivation layer-200; second passivation layer-300; second passivation inner layer 310; second passivation outer layer 320; third passivation layer-400; fourth passivation layer-500; fourth passivation inner layer-510; fourth passivation outer layer-520; first doped layer-600; second doped layer-700; first transparent conductive layer-800; second transparent conductive layer-900; first electrode-110; second electrode-120. DETAILED DESCRIPTION

[0037] In the description of this embodiment, it should be understood that the terms "length", "width", "height", "up", "down", "left", "right", "vertical", "horizontal", "bottom", "inside" and "outside" etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0038] As a specific embodiment of the present invention, Figure 1 As shown, this embodiment provides a method for preparing a heterojunction solar cell, and the preparation method may include:

[0039] Depositing a first passivation layer 200 and a second passivation layer 300 on the first passivation layer 200 on the first surface of the substrate 100;

[0040] Depositing a third passivation layer 400 and a fourth passivation layer 500 on the third passivation layer 400 on the second surface of the substrate 100;

[0041] A first doping layer 600 and a second doping layer 700 are deposited on the second passivation layer 300 and the fourth passivation layer 500, respectively; the first doping layer 600 and the second doping layer 700 have different doping types, for example, the first doping layer 600 is n-type doped and the second doping layer 700 is p-type doped, or the first doping layer 600 is p-type doped and the second doping layer 700 is n-type doped.

[0042] Depositing a first transparent conductive layer 800 and a second transparent conductive layer 900 on the first doping layer 600 and the second doping layer 700 respectively;

[0043] A first electrode 110 and a second electrode 120 are prepared on the first transparent conductive layer 800 and the second transparent conductive layer 900; wherein,

[0044] The first passivation layer 200 and the third passivation layer 400 are deposited under the first reaction condition, and the second passivation layer 300 and the fourth passivation layer 500 are prepared under the second reaction condition. The process parameters of the first reaction condition and the second reaction condition are different.

[0045] Specifically, the reaction conditions of the first passivation layer 200 and the third passivation layer 400 in this embodiment are both the first reaction conditions. The reaction conditions of the second passivation layer 300 and the fourth passivation layer 500 are both the second reaction conditions. The process parameters of the first reaction condition and the second reaction condition are different, so that the first passivation layer 200 and the second passivation layer 300 prepared on the same side of the substrate 100 can have different properties, and the third passivation layer 400 and the fourth passivation layer 500 on the other side of the substrate 100 have different properties, thereby satisfying the anti-epitaxial and passivation effects of the passivation layer of the solar cell.

[0046] It should be noted that the specific process parameters of the first passivation layer 200 and the third passivation layer 400 prepared under the first reaction condition may be completely the same or not completely the same. In the case of not being completely the same, their key process parameters, such as pressure, power density, frequency, deposition chamber temperature, gas flow rate, etc., are all within the numerical range of the first reaction condition;

[0047] The specific process parameters for preparing the second passivation layer 300 and the fourth passivation layer 500 under the second reaction condition may be completely the same or not completely the same. In the case of not completely the same, the key process parameters, such as pressure, power density, frequency, deposition chamber temperature, gas flow rate, etc., are all within the numerical range of the second reaction condition.

[0048] Specifically, generally speaking, the first passivation layer 200 and the third passivation layer 400 located close to the substrate 100 mainly play a role in preventing epitaxy, while the second passivation layer 300 and the fourth passivation layer 500 located far from the substrate 100 mainly play a role in passivation. Therefore, the reaction conditions for preparing the first passivation layer 200 and the second passivation layer 300, and the third passivation layer 400 and the fourth passivation layer 500 are different.

[0049] More specifically, the pressure in the first reaction condition in this embodiment is lower than the pressure in the second reaction condition, and the power density in the first reaction condition is lower than the power density in the second reaction condition.

[0050] Specifically, in this embodiment, by selecting a higher power for preparing the second passivation layer 300 and the fourth passivation layer 500 than the power for preparing the first passivation layer 200 and the third passivation layer 400, and selecting a higher pressure for preparing the second passivation layer 300 and the fourth passivation layer 500 than the pressure for preparing the first passivation layer 200 and the third passivation layer 400, a good passivation effect of the second passivation layer 300 and the fourth passivation layer 500 can be achieved.

[0051] Specifically, the first passivation layer 200 , the second passivation layer 300 , the third passivation layer 400 , and the fourth passivation layer 500 of the present embodiment may all be intrinsic amorphous silicon.

[0052] As a specific embodiment of the present invention, the pressure in the first reaction condition of this embodiment is 0.4-0.8 torr, and the power density is 30-50 mW / cm 2 The pressure in the second reaction condition is 1.5-2.1 torr, and the power density is 35-70 mW / cm 2 . More specifically, the frequency in the second reaction condition of this embodiment is 13.56 MHz, the deposition chamber temperature is 150°C to 230°C, the silane flow rate is 400 to 800 sccm, and the hydrogen flow rate is 5000 to 20000 sccm. The silane flow rate can be 400 sccm, 500 sccm, 600 sccm, 700 sccm or 800 sccm. The hydrogen flow rate can be 5000 sccm, 10000 sccm or 20000 sccm. The hydrogen dilution ratio (silane and hydrogen flow ratio) of this embodiment ranges from 6 to 50.

[0053] Specifically, this embodiment has a better passivation effect through the second reaction condition due to its higher pressure, higher power density and higher hydrogen flow rate, and is beneficial to the subsequent growth of microcrystalline silicon, improving the crystallization rate of the microcrystalline silicon layer, and thus improving the efficiency of the battery.

[0054] The pressure in the second reaction condition of this embodiment is 1.5 torr to 2.1 torr, and the power density is 35 mW / cm 2 ~70mW / cm 2 For example, the pressure of the second reaction condition may be 1.5 torr, 1.8 torr, or 2.1 torr. The power density may be 35 mW / cm 2 、40mW / cm 2 , 45mW / cm 2 、50mW / cm 2 、55mW / cm 2 、60mW / cm 2 、65mW / cm 2 or 70mW / cm 2 Under this pressure and power density, the plasma capacity is low, the bombardment on the passivation layer is small, and the structures of the grown second passivation layer 300 and the fourth passivation layer 500 are relatively loose, which is conducive to the growth of subsequent microcrystalline silicon doping layers 600 and 700, thereby increasing the crystallization rate of microcrystals, improving the electron transmission inside the heterojunction battery, and reducing the series resistance.

[0055] The pressure range and power density range in the second reaction condition of this embodiment, combined with the hydrogen flow rate and hydrogen dilution ratio, have shown through optical testing to have relatively better film quality, wherein the Si-H bond content is higher, and more passivated dangling bonds are present. The optical refractive index of the film is close to 4.30, which can take into account both the passivation effect and the growth of the microcrystalline silicon doped layers 600 and 700, and obtain a higher open circuit voltage in the electrical performance test of the manufactured heterojunction battery.

[0056] As a specific embodiment of the present invention, the hydrogen flow rate when preparing the first intrinsic amorphous silicon layer 200 in this embodiment is 0.

[0057] Specifically, in the present embodiment, when preparing the first intrinsic amorphous silicon layer 200 , no hydrogen is added during the reaction, and the prepared first intrinsic amorphous silicon layer 200 can well prevent epitaxy.

[0058] As another specific embodiment of the present invention, Figure 2 As shown, the method for preparing a solar cell of this embodiment may include:

[0059] Depositing a first passivation layer 200 and a second passivation layer 300 on the first passivation layer 200 on the first surface of the substrate 100;

[0060] Depositing a third passivation layer 400 and a fourth passivation layer 500 on the third passivation layer 400 on the second surface of the substrate 100;

[0061] Depositing a first doping layer 600 and a second doping layer 700 on the second passivation layer 300 and the fourth passivation layer respectively;

[0062] Depositing a first transparent conductive layer 800 and a second transparent conductive layer 900 on the first doping layer 600 and the second doping layer 700 respectively;

[0063] A first electrode 110 and a second electrode 120 are formed on the first transparent conductive layer 800 and the second transparent conductive layer 900; wherein the second passivation layer 300 may include a second passivation inner layer 310 and a second passivation outer layer 320, and the fourth passivation layer 500 may include a fourth passivation inner layer 510 and a fourth passivation outer layer 520;

[0064] The first passivation layer 200 and the third passivation layer 400 are deposited under the first reaction condition, and the second passivation outer layer 320 and the fourth passivation outer layer 520 are prepared under the second reaction condition. The process parameters of the first reaction condition and the second reaction condition are different.

[0065] Specifically, the first passivation layer 200 , the second passivation inner layer 310 , the second passivation outer layer 320 , the third passivation layer 400 , the fourth passivation inner layer 510 and the fourth passivation outer layer 520 of the present embodiment may all be intrinsic amorphous silicon.

[0066] As in the above embodiment, the reaction conditions of the first passivation layer 200 and the third passivation layer 400 in this embodiment are both the first reaction conditions. The reaction conditions of the second passivation outer layer 320 and the fourth passivation outer layer 520 are both the second reaction conditions. However, the process parameters of the first reaction condition and the second reaction condition are different, so that the first passivation layer 200 and the second passivation layer 300 prepared on the same side of the substrate 100 can have different properties, and the third passivation layer 400 and the fourth passivation layer 500 on the other side of the substrate 100 have different properties, thereby satisfying the anti-epitaxial and passivation effects of the passivation layer of the solar cell.

[0067] As in the above embodiment, the specific process parameters of the first passivation layer 200 and the third passivation layer 400 prepared under the first reaction condition may be completely the same or not completely the same. In the case of not completely the same, the key process parameters, such as pressure, power density, frequency, deposition chamber temperature, gas flow rate, etc., are all within the numerical range of the first reaction condition.

[0068] The specific process parameters for preparing the second passivation outer layer 320 and the fourth passivation outer layer 520 under the second reaction condition may be completely the same or not completely the same. In the case of not completely the same, the key process parameters, such as pressure, power density, frequency, deposition chamber temperature, gas flow rate, etc., are all within the numerical range of the second reaction condition.

[0069] Specifically, generally speaking, the first passivation layer 200 and the third passivation layer 400 located at the bottom mainly play a role in preventing epitaxy, while the second passivation outer layer 320 and the fourth passivation outer layer 520 mainly play a role in passivation. Therefore, the reaction conditions for preparing the first passivation layer 200 and the second passivation outer layer 320 and the third passivation layer 400 and the fourth passivation outer layer 520 are different.

[0070] More specifically, the pressure in the first reaction condition in this embodiment is lower than the pressure in the second reaction condition, and the power density in the first reaction condition is lower than the power density in the second reaction condition.

[0071] Specifically, in this embodiment, by selecting a higher power for preparing the second passivation outer layer 320 and the fourth passivation outer layer 520 than the power for preparing the first passivation layer 200 and the third passivation layer 400, and selecting a higher pressure for preparing the second passivation outer layer 320 and the fourth passivation outer layer 520 than the pressure for preparing the first passivation layer 200 and the third passivation layer 400, a good passivation effect of the second passivation outer layer 320 and the fourth passivation outer layer 520 can be achieved.

[0072] As a specific embodiment of the present invention, the pressure in the first reaction condition of this embodiment is 0.4-0.8 torr, and the power density is 30-50 mW / cm 2 The pressure in the second reaction condition is 1.5-2.1 torr, and the power density is 35-70 mW / cm 2 . More specifically, the frequency in the second reaction condition of this embodiment is 13.56 MHz, the deposition chamber temperature is 150°C to 230°C, the silane flow rate is 400 to 800 sccm, and the hydrogen flow rate is 5000 to 20000 sccm. The silane flow rate can be 400 sccm, 500 sccm, 600 sccm, 700 sccm or 800 sccm. The hydrogen flow rate can be 5000 sccm, 10000 sccm or 20000 sccm. The hydrogen dilution ratio (silane and hydrogen flow ratio) of this embodiment ranges from 6 to 50.

[0073] Specifically, this embodiment has a better passivation effect through the second reaction condition due to its higher pressure, higher power density and higher hydrogen flow rate, and is beneficial to the subsequent growth of microcrystalline silicon, improving the crystallization rate of the microcrystalline silicon layer, and thus improving the efficiency of the battery.

[0074] In addition, since there is a high hydrogen flow rate when preparing the second passivation outer layer 320 and the fourth passivation outer layer 520, hydrogen will have a strong bombardment effect on the bottom layer, so in this embodiment, the second passivation inner layer 310 is set between the first passivation layer 200 and the second passivation outer layer 320, and the fourth passivation inner layer 510 is set between the third passivation layer 400 and the fourth passivation outer layer 520, and the reaction conditions for preparing the second passivation inner layer 310 and the fourth passivation inner layer 510 are both the third conditions, and the hydrogen flow rate in the third reaction condition is less than the hydrogen flow rate in the second reaction condition. In this way, the hydrogen flow rate in preparing the second passivation inner layer 310 and the fourth passivation inner layer 510 can be less, the bombardment of the first passivation layer 200 and the third passivation layer 400 is less, and the damage to the first passivation layer 200 and the third passivation layer 400 is reduced, and the anti-epitaxial effect of the first passivation layer 200 and the third passivation layer 400 is not affected.

[0075] As in the above embodiment, the specific process parameters of the second passivation inner layer 310 and the fourth passivation inner layer 510 prepared under the third reaction condition may be completely the same or not completely the same. In the case of not completely the same, the key process parameters, such as pressure, power density, frequency, deposition chamber temperature, gas flow rate, etc., are all within the numerical range of the first reaction condition.

[0076] In addition, specifically, the power density of the second reaction condition of this embodiment is greater than or equal to the power density of the third reaction condition, and the pressure of the second reaction condition is greater than or equal to the pressure of the third reaction condition.

[0077] More specifically, the power density and pressure in the third reaction condition of the present embodiment are both less than or equal to the power density and pressure in the second reaction condition. Although the third reaction condition selects low power, low pressure, and low hydrogen flow (compared with the second reaction condition), it weakens the auxiliary property to the subsequent microcrystalline growth, and the improvement of the crystallization rate becomes less, but due to the presence of the second passivation outer layer 320 and the fourth passivation outer layer 520, the overall passivation effect and the growth effect on the subsequent microcrystalline doped layer are small. In addition, the second passivation inner layer 310 and the fourth passivation inner layer 510 are prepared under the third reaction condition, which reduces the bombardment damage to the first passivation layer 200 and the third passivation layer 400 anti-epitaxial layer, further improving the anti-epitaxial effect, and the passivation and the subsequent microcrystalline doped layer growth are compared. Compared with the effect of the gain improvement of the battery.

[0078] As a specific embodiment of the present invention, this embodiment also provides a heterojunction solar cell, which is prepared by the above preparation method.

[0079] The following is a detailed description with reference to specific embodiments.

[0080] Example 1

[0081] The steps for preparing the heterojunction solar cell of this embodiment include:

[0082] 1) Selecting an N-type single crystal silicon wafer as the substrate 100, performing texturing on the front and back sides of the substrate 100, the texturing method is a conventional alkaline solution + additive texturing to form a double-sided pyramid;

[0083] 2) depositing a first passivation layer 200 on the first surface of the textured substrate 100, and depositing a second passivation layer 300 on the first passivation layer 200;

[0084] 3) depositing a third passivation layer 400 and a fourth passivation layer 500 on the third passivation layer 400 on the second surface of the substrate 100 .

[0085] The first passivation layer 200 and the third passivation layer 400 are deposited under the first reaction condition. The first reaction condition is to use an RF power supply with a frequency of 13.56 MHz, a deposition gas pressure of 0.57 torr, a silane flow rate of 600 sccm, a deposition thickness of 1.5 nm, and a deposition power of 350 W;

[0086] The second passivation layer 300 and the fourth passivation layer 500 are prepared under the second reaction conditions, wherein the second reaction conditions are to use an RF power supply with a frequency of 13.56 MHz, a deposition gas pressure of 1.5 torr, a silane flow rate of 500 sccm, a hydrogen flow rate of 10000 sccm, a deposition power of 500 W, and a thickness of the second passivation layer 300 deposited on the front side of 6 nm and a thickness of 5 nm deposited on the back side.

[0087] 4) depositing a first doping layer 600 and a second doping layer 700 on the second passivation layer 300 and the fourth passivation layer respectively; specifically, the first doping layer 600 and the second doping layer 700 in the present embodiment cannot be prepared at the same time, and it is necessary to prepare the doping layer on one side first, and then flip the cell sheet over before preparing the doping layer on the other side. For example, first prepare the first passivation layer 200 and the second passivation layer 300 in sequence on one side of the substrate 100, and flip the cell sheet over; prepare the third passivation layer 400 and the fourth passivation layer 500 in sequence on the other side of the substrate 100, deposit the second doping layer 700 on the fourth passivation layer 500, and flip the cell sheet over; and then deposit the first doping layer 600 on the second passivation layer 300. Of course, the above process may also be modified, which will not be further explained here.

[0088] 5) A first transparent conductive layer 800 and a second transparent conductive layer 900 are respectively deposited on the first doped layer 600 and the second doped layer 700. Here, the order of depositing the first transparent conductive layer 800 and the second transparent conductive layer 900 is not limited, and the first transparent conductive layer 800 may be deposited first and then the second transparent conductive layer 900, or the second transparent conductive layer 900 may be deposited first and then the first transparent conductive layer 800.

[0089] 6) The first electrode 110 and the second electrode 120 are prepared on the first transparent conductive layer 800 and the second transparent conductive layer 900. Here, the order of preparing the first electrode 110 and the second electrode 120 is not limited. In addition, the first electrode 110 and the second electrode 120 can be prepared by printing, or by electroplating, which belongs to the conventional process in the art and is not further described here.

[0090] Example 2

[0091] 1) is the same as step 1) of Example 1,

[0092] 2) A first passivation layer 200 is deposited on the first surface of the textured substrate 100 , a second passivation inner layer 310 is deposited on the first passivation layer 200 , and a second passivation outer layer 320 is deposited on the second passivation inner layer 310 .

[0093] 3) A third passivation layer 400 is deposited on the second surface of the textured substrate 100 , a fourth passivation inner layer 510 is deposited on the third passivation layer 400 , and a fourth passivation outer layer 520 is deposited on the fourth passivation inner layer 510 .

[0094] The first passivation layer 200 and the third passivation layer 400 are deposited under the first reaction condition, wherein the first reaction condition is to use an RF power source with a frequency of 13.56 MHz, a deposition gas pressure of 0.57 torr, a silane flow rate of 600 sccm, a deposition thickness of 1.5 nm, and a deposition power of 350 W.

[0095] The second passivation outer layer 320 and the fourth passivation outer layer 520 are deposited under the second reaction conditions. The second reaction conditions are:

[0096] Using RF power supply, the frequency is 13.56MHz, the deposition gas pressure is 1.5torr, the silane flow rate is 500sccm, the hydrogen flow rate is 10000sccm, the deposition power is 500W, the front deposition is 3nm, and the back deposition is 2.5nm.

[0097] The second passivation inner layer 310 and the fourth passivation inner layer 510 are deposited under the third reaction condition. The third reaction condition is: using RF power, frequency of 13.56 MHz, pressure of 0.5 torr, silane flow rate of 500, hydrogen flow rate of 500, deposition power of 200 W, deposition power density of 13.5 mW / cm 2 , 3nm is deposited on the front side and 2.5nm is deposited on the back side.

[0098] 4) is the same as step 4) of Example 1;

[0099] 5) is the same as step 5) of Example 1;

[0100] 6) is the same as step 6) of Example 1.

[0101] Comparative Example

[0102] The steps are the same as those in Example 1, except that the reaction conditions for depositing the second passivation layer 300 and the fourth passivation layer 500 are: gas pressure of 0.4 torr, silane flow rate of 500 sccm, hydrogen flow rate of 500 sccm, deposition power of 200 W, front deposition thickness of 6 nm, and back deposition thickness of 5 nm.

[0103] Result analysis:

[0104] In the above-mentioned Example 1, Example 2 and Comparative Example,

[0105] The quality of the film layer prepared by the first reaction conditions (the preparation conditions of the first passivation layer 200 and the second passivation layer 400 in Example 1 and the preparation conditions of the first passivation layer 200 and the second passivation layer 400 in Example 2) and the quality of the film layer prepared by the second reaction conditions (the preparation conditions of the second passivation layer 300 and the fourth passivation layer 500 in the comparative example and the preparation conditions of the second passivation outer layer 320 and the fourth passivation outer layer 520 in Example 2) were analyzed.

[0106] Structure factor test comparison:

[0107] The film quality of the second passivation layer 300 and the fourth passivation layer 500 in Example 1 and the comparative example was tested by Fourier transform infrared absorption spectrometer. The results show that the structure factor R of the second passivation layer 300 and the fourth passivation layer 500 deposited by the second reaction conditions in Example 1 is 2.51%. The structure factor R of the second passivation layer 300 and the fourth passivation layer 500 deposited by the reaction conditions in the comparative example is 4.30%. It shows that the second passivation layer 300 and the fourth passivation layer 500 deposited by the second reaction conditions in Example 1 have more Si-H bonds and better film quality.

[0108] The performance comparison of the heterojunction solar cells obtained in the above-mentioned Example 1, Example 2 and Comparative Example is shown in the figure below: Figure 3 (a), 3(b), 3(c) and 3(d), and the final data table is shown in Table 1 below.

[0109] Table 1

[0110]

[0111] The performance of the heterojunction solar cells prepared in the comparative example and in Example 1 and Example 2 is compared and analyzed as follows:

[0112] Test comparison of minority carrier lifetime:

[0113] The passivation effect of the intrinsic amorphous silicon passivation layer was tested using a Sinton WCT-120 minority carrier lifetime tester. Specifically, the minority carrier lifetime of the tested silicon wafer after the passivation layer was deposited by the method of Example 1 was 1956μs, and the minority carrier lifetime of the tested silicon wafer after the passivation layer was deposited by the method of Example 2 was 2011μs. The minority carrier lifetime of the tested silicon wafer after the passivation layer was deposited by the comparative method was 1684μs. This shows that the passivation effect of the intrinsic amorphous silicon passivation layer deposited by Examples 1 and 2 has been improved.

[0114] Fill factor comparison:

[0115] The filling factor of the heterojunction solar cell prepared in Example 1 is 85.68%, the filling factor of the heterojunction solar cell prepared in Example 2 is 85.72%, and the filling factor of the heterojunction solar cell prepared in the comparative example is 85.40%. This shows that the filling factor is higher under the conditions in Example 1 and Example 2, indicating that the photoelectric conversion efficiency of the heterojunction solar cell prepared under the conditions in Example 1 and Example 2 is higher.

[0116] Crystallization rate comparison:

[0117] After the second passivation layer 300 and the fourth passivation layer 500 are deposited by the method in this embodiment 1, the crystallization rate of the microcrystalline P layer in the subsequent doping layer 600 / 700 reaches 52%. The crystallization rate of the microcrystalline P layer in the subsequent doping layer 600 / 700 in embodiment 2 reaches 50%. However, the crystallization rate of the microcrystalline P layer in the subsequent doping layer 600 / 700 in the comparative example is only 45%. This shows that the second passivation layer 300 or the fourth passivation layer 500 prepared by the second reaction condition can effectively improve the crystallization rate of the microcrystalline P layer in the doping layer 600 / 700. However, in Example 2, since the second passivation layer 300 includes the second passivation inner layer 310 and the second passivation outer layer 320, the fourth passivation layer 500 includes the fourth passivation inner layer 510 and the fourth passivation outer layer 520, the second passivation outer layer 320 and the fourth passivation outer layer 520 are both prepared using the second reaction conditions, and the second passivation inner layer 310 and the fourth passivation inner layer 510 are both passivation layers prepared using the third reaction conditions. Since the second passivation inner layer 310 and the fourth passivation inner layer 510 are deposited under low pressure, low power density and low hydrogen flow conditions, the second passivation inner layer 310 and the fourth passivation inner layer 510 only serve as buffer layers that take into account the passivation effect and prevent the deposition of the second passivation outer layer 320 and the fourth passivation outer layer 520 from weakening the anti-epitaxial effect of the first passivation layer 200 and the third passivation layer 400. The second passivation inner layer 310 and the fourth passivation inner layer 510 are not conducive to the crystallization of the subsequent microcrystalline doped layer. Therefore, the crystallization rate is lower than the crystallization rate of the second passivation layer 300 and the fourth passivation layer 500 prepared only using the second reaction conditions in Example 1.

[0118] Open circuit voltage comparison:

[0119] The heterojunction solar cell prepared by using Example 1 showed an open circuit voltage of 750.9mV in the IV test. The heterojunction solar cell prepared by using Example 2 showed an open circuit voltage of 751.1mV in the IV test. The open circuit voltage of the heterojunction solar cell prepared in the comparative example was 750.6mV. This shows that the open circuit voltage of the heterojunction solar cell prepared by using Example 1 and Example 2 is slightly higher than the open circuit voltage of the heterojunction solar cell obtained under the conditions in the comparative example. The reason is that the second passivation layer 300 or the fourth passivation layer 500 deposited by the second reaction conditions can improve the passivation effect and thus increase the open circuit voltage of the solar cell. However, in Example 1, due to the high hydrogen flow rate in the second reaction condition, the bombardment of the first passivation layer is relatively large, thereby weakening its anti-epitaxial performance, which will also reduce the open circuit voltage of the solar cell. The two then offset each other, resulting in a smaller impact on the open circuit voltage. In Example 2, since the second passivation outer layer 320 and the fourth passivation outer layer 520 are provided which take into account the passivation effect and serve as a buffer layer, the bombardment of the second passivation inner layer 310 and the fourth passivation inner layer 510 on the anti-epitaxial layers of the first passivation layer 200 and the third passivation layer 400 is weakened, the anti-epitaxial effect is improved, and thus the open circuit voltage of the heterojunction solar cell is improved.

[0120] Series resistance comparison:

[0121] The series resistance of the heterojunction solar cell prepared by Example 1 is 1.16 mΩ. The series resistance of the heterojunction solar cell prepared by Example 2 is 1.27 mΩ. The series resistance of the heterojunction solar cell prepared in the comparative example is 1.47 mΩ. The passivation layer prepared by Example 1 and Example 2 promotes the crystallization of the microcrystals of the doped layer, improves the carrier transport performance, and effectively reduces the series resistance of the heterojunction solar cell.

[0122] Battery conversion efficiency comparison:

[0123] The cell conversion efficiency of the heterojunction solar cell prepared by this embodiment 1 is 25.33%. The cell conversion efficiency of the heterojunction solar cell prepared by embodiment 2 is 25.35%. The cell conversion efficiency of the heterojunction solar cell prepared in the comparative example is 25.30%. This shows that the heterojunction solar cells prepared under the conditions in embodiment 1 and embodiment 2 can improve the cell conversion efficiency.

[0124] At this point, those skilled in the art should recognize that, although multiple exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications that conform to the principles of the present invention can still be directly determined or derived based on the content disclosed in the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and recognized as covering all these other variations or modifications.

Claims

1. A method for preparing a heterojunction solar cell, characterized in that: include: depositing a first passivation layer and a second passivation layer on the first passivation layer on the first surface of the substrate; depositing a third passivation layer and a fourth passivation layer on the third passivation layer on the second surface of the substrate; Depositing a first doping layer and a second doping layer on the second passivation layer and the fourth passivation layer, respectively; depositing a first transparent conductive layer and a second transparent conductive layer on the first doped layer and the second doped layer respectively; A first electrode and a second electrode are prepared on the first transparent conductive layer and the second transparent conductive layer; wherein, Depositing a first passivation layer and a third passivation layer under a first reaction condition, and preparing a second passivation layer and a fourth passivation layer under a second reaction condition, wherein the process parameters of the first reaction condition and the second reaction condition are different; or The second passivation layer includes a second passivation inner layer and a second passivation outer layer, and the fourth passivation layer includes a fourth passivation inner layer and a fourth passivation outer layer; The first passivation layer and the third passivation layer are deposited under the first reaction condition, and the second passivation outer layer and the fourth passivation outer layer are prepared under the second reaction condition, wherein the process parameters of the first reaction condition and the second reaction condition are different.

2. The method for preparing a heterojunction solar cell according to claim 1, characterized in that: The pressure in the first reaction condition is lower than the pressure in the second reaction condition, and the power density in the first reaction condition is lower than the power density in the second reaction condition.

3. The method for preparing a heterojunction solar cell according to claim 2, characterized in that: The pressure in the first reaction condition is 0.4-0.8 torr, and the power density is 30-50 mW / cm 2 The pressure of the second reaction condition is 1.5 to 2.1 torr, and the power density is 35 to 70 mW / cm 2 .

4. The method for preparing a heterojunction solar cell according to claim 3, characterized in that: In the first reaction condition, the frequency is 13.56 MHz, the temperature of the deposition chamber is 150° C. to 230° C., and the silane flow rate is 400 to 800 sccm.

5. The method for preparing a heterojunction solar cell according to any one of claims 1 to 4, characterized in that: The second passivation inner layer and the fourth passivation inner layer are deposited under third reaction conditions, wherein the hydrogen flow rate in the third reaction conditions is less than the hydrogen flow rate in the second reaction conditions.

6. The method for preparing a heterojunction solar cell according to claim 5, characterized in that: The pressure of the second reaction condition is greater than or equal to the pressure of the third reaction condition.

7. The method for preparing a heterojunction solar cell according to any one of claims 1 to 4, characterized in that: The first passivation layer, the second passivation layer, the third passivation layer and the fourth passivation layer are all made of intrinsic amorphous silicon.

8. The method for preparing a heterojunction solar cell according to any one of claims 1 to 4, characterized in that: Under the first reaction condition, the hydrogen flow rate is 0 sccm.

9. The method for preparing a heterojunction solar cell according to any one of claims 1 to 4, characterized in that: The thickness of the first passivation layer and the third passivation layer is 1.5-2.5 nm, and the thickness of the second passivation layer and the fourth passivation layer is 4-8 nm.

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

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