Solar cell and preparation method thereof

Abstract

The invention discloses a solar cell and a preparation method thereof, and relates to the technical field of solar cell manufacturing, and the solar cell specifically comprises a silicon substrate and an anti-reflection layer arranged on at least one side of the silicon substrate in the thickness direction; the anti-reflection layer comprises a plurality of transmission grating layers which are arranged in a stacked mode. Each transmission grating layer comprises a plurality of parallel light-transmitting slits which are distributed at intervals; the extending directions of the light-transmitting slits of the multiple transmission grating layers are different. According to the embodiment, the anti-reflection layer is arranged to be of the stacked structure of the multiple transmission grating layers with the light-transmitting slits extending in the different directions, so that the nanometer Moire grating structure jointly formed by the multiple transmission grating layers can effectively improve the light transmission performance, and the nanometer Moire grating structure is particularly suitable for an anti-reflection material with the refractive index lower than that of a silicon substrate; the light reflection can be better reduced while the good passivation performance of the material is utilized.

Description

Technical Field

[0001] The present invention relates to the technical field of solar cell manufacturing, and particularly to a solar cell and a preparation method thereof. Background Art

[0002] In the existing solar cell structure, an antireflection layer is usually provided on the side of incident light to reduce the reflection of incident sunlight, so that more sunlight can enter the silicon substrate and the light conversion performance of the solar cell can be increased. Specifically, the existing antireflection layer often utilizes the size relationship between refractive indices. By inserting an antireflection layer with a refractive index of N1 between two layers of media with refractive indices of N0 (air) and N2 (silicon substrate), the reflectivity is gradually reduced layer by layer. However, for materials such as alumina that have excellent passivation performance themselves, their refractive indices are often lower than that of the silicon substrate (N2), resulting in some sunlight still being reflected and an excellent antireflection effect not being achieved. Summary of the Invention

[0003] In view of this, an embodiment of the present invention provides a solar cell and a preparation method thereof. By setting the antireflection layer as a stacked structure of multiple transmission grating layers with different extending directions of light-transmitting slits, the nano-Moiré grating structure formed by the multiple transmission grating layers together can effectively increase the light transmission performance, especially applicable to antireflection materials with a refractive index lower than that of the silicon substrate. Compared with the prior art, while utilizing the good passivation performance of the material, light reflection can be better reduced.

[0004] To solve the above technical problems, the present invention provides the following technical solutions:

[0005] In a first aspect, the present invention provides a solar cell, including: a silicon substrate, and an antireflection layer provided on at least one side in the thickness direction of the silicon substrate; wherein, the antireflection layer includes multiple stacked transmission grating layers; each transmission grating layer includes multiple parallel and spaced light-transmitting slits; and the extending directions of the light-transmitting slits of the multiple transmission grating layers are different.

[0006] Optionally, the transmission grating layer is three layers, and the included angle between the light-transmitting slits corresponding to each adjacent two transmission grating layers is 10° - 70°.

[0007] Optionally, the included angle between the light-transmitting slits corresponding to each adjacent two transmission grating layers is 30° - 60°.

[0008] Optionally, the included angle between the light-transmitting slits corresponding to any adjacent two transmission grating layers is the same.

[0009] Optionally, the thickness of the middle transmission grating layer is the same as that of the outermost transmission grating layer; and / or, the thickness of the innermost transmission grating layer is greater than that of the outermost transmission grating layer.

[0010] Optionally, the thickness of the innermost transmission grating layer is 1.5 nm to 5 nm; and / or, the thickness of the middle transmission grating layer is 0.5 nm to 2 nm; and / or, the thickness of the outermost transmission grating layer is 0.5 nm to 2 nm.

[0011] Optionally, the thickness of the antireflection layer is 3.5 nm to 7 nm.

[0012] In a second aspect, the present invention provides a method for manufacturing a solar cell, including: sequentially manufacturing multiple transmission grating layers on at least one side in the thickness direction of a silicon substrate by using a plate-type atomic layer deposition method; wherein, each of the transmission grating layers includes multiple parallel and spaced-apart light-transmitting slits, and the extending directions of the light-transmitting slits of the multiple transmission grating layers are different.

[0013] The technical solution of the first aspect of the above invention has the following advantages or beneficial effects: By setting the antireflection layer as a stacked structure of multiple transmission grating layers with different extending directions of the light-transmitting slits, the nano-Moiré grating structure jointly formed by the multiple transmission grating layers can effectively improve the light transmission performance, especially suitable for antireflection materials with a refractive index lower than that of the silicon substrate. Compared with the prior art, while utilizing the good passivation performance of the material, light reflection can be better reduced. Description of the Drawings

[0014] The drawings are used to better understand the present invention and do not constitute an improper limitation to the present invention. Among them:

[0015] Figure 1 is a schematic cross-sectional structure diagram of a solar cell according to an embodiment of the present invention;

[0016] Figure 2 is a schematic diagram of the stacked structure of a transmission grating layer according to an embodiment of the present invention;

[0017] Figure 3 is a schematic diagram of another stacked structure of a transmission grating layer according to an embodiment of the present invention;

[0018] Figure 4 is a schematic diagram of still another stacked structure of a transmission grating layer according to an embodiment of the present invention;

[0019] Figure 5 is a schematic main flow diagram of a method for manufacturing a solar cell according to an embodiment of the present invention;

[0020] Figure 6It is a schematic diagram of the main process for preparing a multi-layer transmissive grating layer according to an embodiment of the present invention;

[0021] Figure 7 It is a schematic diagram of the device for plate-type atomic layer deposition according to an embodiment of the present invention.

[0022] The reference numerals are as follows:

[0023] 1 - silicon substrate; 2 - antireflection layer; 21 - transmissive grating layer; 3 - passivation layer. Detailed implementation manners

[0024] A solar cell is a photovoltaic semiconductor thin slice that directly generates electricity using sunlight, also known as a "solar chip" or "photovoltaic cell". As long as it is irradiated by light with a certain illuminance condition, it can instantaneously output voltage and generate current in the case of a loop. It is called solar photovoltaics (abbreviated as PV) in physics, simply referred to as PV. For the convenience and clear description of the preparation method of the solar cell of the present invention and the solar cell, the following makes an illustration of the exemplary embodiments of the present invention in conjunction with the accompanying drawings, including various details of the embodiments of the present invention to facilitate understanding, and they should be considered merely exemplary. Therefore, those of ordinary skill in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present invention. Similarly, for the sake of clarity and conciseness, the description of well-known functions and structures is omitted below.

[0025] Figure 1 It shows a schematic cross-sectional structure diagram of the solar cell provided by the embodiment of the present invention. As Figure 1 shown, the solar cell provided by the present invention includes: a silicon substrate 1, and an antireflection layer 2 provided on at least one side in the thickness direction of the silicon substrate 1; wherein, the antireflection layer 2 includes a plurality of stacked transmissive grating layers 21; each transmissive grating layer 21 includes a plurality of parallel and spaced-apart light-transmitting slits; the extending directions of the light-transmitting slits of the plurality of transmissive grating layers 21 are different.

[0026] It can be understood that for each transmissive grating layer 21, the plurality of parallel and spaced-apart light-transmitting slits can decompose the incident sunlight into spectra of different wavelengths through the diffraction effect. When the frequency of the incident photons matches the vibration frequency of the free electrons on the surface of the nanostructure, the nanoparticles will have a strong absorption effect on the incident photons, thereby causing the local surface plasmon resonance phenomenon. Therefore, the embodiment of the present invention precisely utilizes this principle to adjust the extending angles of the light-transmitting slits between the plurality of transmissive grating layers 21 so that the nanostructured grating formed by the plurality of transmissive grating layers 21 can match the frequency of the incident sunlight, thereby improving the absorption efficiency of sunlight. Specifically, from Figure 1It can be seen that each transmissive grating layer 21 is composed of a plurality of parallel and spaced-apart light-transmitting slits, and the extending directions of the multiple transmissive grating layers 21 are all different.

[0027] In an alternative embodiment, the transmissive grating layer 21 has three layers, and the included angle between the light-transmitting slits corresponding to every two adjacent transmissive grating layers 21 is 10° to 70°, such as 10°, 20°, 30°, 40°, 50°, 60°, and 70°, etc. Still taking Figure 1 as an example, when the transmissive grating layer 21 has three layers, the included angles between the innermost transmissive grating layer 21 and the middle transmissive grating layer 21, and between the middle transmissive grating layer 21 and the outermost transmissive grating layer 21 are both 10° to 70°. Among them, for the direction of the included angle between any two adjacent transmissive grating layers 21, as long as the extending directions of the light-transmitting slits of the multiple transmissive grating layers 21 are different, it is not necessarily limited that the direction of the included angle is the same.

[0028] Exemplarily, as Figure 2 shown, taking the extending direction of the light-transmitting slits of the innermost transmissive grating layer 21 as the main direction as an example, the extending direction of the light-transmitting slits of the middle transmissive grating layer 21 can be rotated 70° to the left (i.e., the first direction) from the main direction. Further, the extending direction of the light-transmitting slits of the outermost transmissive grating layer 21 can be rotated 30° to the right (i.e., the second direction) on the basis of the first direction, thereby obtaining three transmissive grating layers 21 with different extending directions from a top view angle.

[0029] Exemplarily, it can also be as Figure 3 shown. Still taking the extending direction of the light-transmitting slits of the innermost transmissive grating layer 21 as the main direction as an example, the extending direction of the light-transmitting slits of the middle transmissive grating layer 21 can be rotated 40° to the left (i.e., the first direction) from the main direction, and then continue to rotate 30° to the left on the basis of the first direction to obtain the outermost transmissive grating layer 21. Although Figure 3 and Figure 2 the grating structures obtained in the top view direction are the same, due to the actual differences in the included angle direction and the included angle between adjacent transmissive grating layers 21, there will be some differences in the final sunlight absorption effect.

[0030] It should be noted that the number of layers of the transmissive grating layer 21 is not limited to three layers, and can also be other numbers of layers more than three. In the embodiment of the present invention, the innermost transmissive grating layer 21 ensures the overall passivation performance of the solar cell, and the subsequent other transmissive grating layers 21 (such as the transmissive grating layer 21 in the middle and the outermost transmissive grating layer 21 among the three layers) mainly play the role of forming the nano-grating structure. Therefore, when the number of layers of the transmissive grating layer 21 is N, the passivation performance of the silicon substrate can be ensured by using the first N - 2 transmissive grating layers 21 located inside, and the light absorption performance of sunlight can be improved by controlling the extension direction and extension angle between the (N - 1)th and Nth transmissive grating layers 21. It should be noted here that each transmissive grating layer 21 is obtained by depositing one or more deposition cycles, and for a single transmissive grating layer 21, there is no position transformation between multiple deposition cycles, that is, the deposition directions of one or more deposition cycles in a single transmissive grating layer 21 are the same. Exemplarily, taking the three transmissive grating layers 21 as an example, the innermost transmissive grating layer 21 can be deposited for 5 deposition cycles, while the transmissive grating layer 21 in the middle and the outermost transmissive grating layer 21 can be deposited for 1 deposition cycle.

[0031] In a further optional embodiment, through continuous adjustment experiments by the inventor on the angle between the light-transmitting slits corresponding to adjacent two transmissive grating layers 21, the angle between the light-transmitting slits corresponding to each adjacent two transmissive grating layers 21 in the embodiment of the present invention is set to 30° - 60°, such as 30°, 40°, 50°, and 60°, etc. Compared with the angle of 10° - 70°, setting the angle to 30° - 60° can better improve the light absorption performance of the multi-layer transmissive grating layer 21 for sunlight.

[0032] In a further optional embodiment, the angle between the light-transmitting slits corresponding to any adjacent two transmissive grating layers 21 is the same. It can be understood that since the extension directions of the light-transmitting slits of the multi-layer transmissive grating layer 21 in the embodiment of the present invention are different, when the angle between the light-transmitting slits corresponding to any adjacent two transmissive grating layers 21 is the same, the rotation directions of the multiple transmissive grating layers 21 are the same (as Figure 3 shown), that is, the situation of overlapping after rotation of the multi-layer transmissive grating layer 21 is avoided (as Figure 4 shown). Specifically, in Figure 4In the embodiment, the transmission grating layer 21 (first direction) in the middle is obtained by rotating 30° to the left on the main direction of the innermost transmission grating layer 21, while the transmission grating layer 21 located on the outermost side is obtained by rotating 30° to the right on the basis of the first direction, which results in the outermost transmission grating layer 21 actually overlapping with the innermost transmission grating layer 21, weakening the nano-grating structure composed of multiple layers of transmission grating layers 21. Moreover, the transmission signal of sunlight in the grating is a sinusoidal transmission signal. The same rotation angle is conducive to the superposition of light intensity, while different angles will cause some sunlight to cancel each other out. Therefore, in the embodiment of the present invention, when the angles between the light-transmitting slits corresponding to any two adjacent layers of transmission grating layers 21 are the same, the rotation directions of multiple transmission grating layers 21 are the same, so as to avoid the overlap of multiple layers of transmission grating layers 21 as much as possible and improve the transmission performance.

[0033] The thickness of the anti-reflection layer 2 is usually controlled by the number of deposition cycles of the deposition process. In actual application, it is sufficient to ensure that the thickness can achieve the effect of reducing the reflection of sunlight, and it should not be too thick or too thin. Usually, the thickness deposited by one deposition cycle is 0.5nm~1nm. Therefore, in an optional embodiment of the present invention, the thickness of the anti-reflection layer 2 is 3.5nm~7nm, such as 3.5nm, 5nm, 6nm, 7nm, etc., that is, it is obtained by multiple deposition cycles. It can be understood that the multiple deposition cycles correspond to the total thickness of the anti-reflection layer 2. Different deposition cycles can be allocated to each transmission grating layer 21 according to actual needs. For example, when the total number of deposition cycles is 7, in addition to the aforementioned 5+1+1 allocation method, it can also be a 3+2+2 allocation method, that is, the transmission grating layer 21 located at the innermost side can be deposited for 3 deposition cycles, and the transmission grating layer located in the middle and the transmission grating layer 21 located at the outermost side can be deposited for 2 deposition cycles. It should be noted that when the thickness of the anti-reflection layer 2 is set too thick, it not only causes material waste, but also increases the process difficulty, which is not conducive to industrial manufacturing. When the thickness of the anti-reflection layer 2 is set too thin, it will affect the anti-reflection effect and reduce the conversion efficiency of sunlight.

[0034] In an alternative embodiment, the thickness of the innermost transmissive grating layer 21 is 1.5 nm to 5 nm, such as 1.5 nm, 2 nm, 2.2 nm, 2.5 nm, 3 nm, 5 nm, etc.; the thickness of the middle transmissive grating layer 21 is 0.5 nm to 2 nm, such as 0.5 nm, 1 nm, 1.2 nm, 1.4 nm, 1.5 nm, 2 nm, etc.; the thickness of the outermost transmissive grating layer 21 is 0.5 nm to 2 nm, such as 0.5 nm, 1 nm, 1.2 nm, 1.4 nm, 1.5 nm, 2 nm, etc. It can be understood that since the purpose of the innermost transmissive grating layer 21 is to ensure the passivation performance, the innermost transmissive grating layer 21 needs to be set thicker, while the middle transmissive grating layer 21 and the outermost transmissive grating layer 21 together form a nano-grating. Through continuous experiments, the inventors found that different thicknesses and different extending directions of the light-transmitting slits will have different effects on the transmission of sunlight. Setting the thicknesses of the middle and outer transmissive grating layers 21 thinner can be more conducive to the downward transmission of sunlight.

[0035] In a further alternative embodiment, the thicknesses of the middle transmissive grating layer 21 and the outermost transmissive grating layer 21 are the same because different thicknesses of the transmissive grating layer 21 will affect the light-transmitting performance of the formed nano-grating structure. Only when the thicknesses of two adjacent transmissive grating layers 21 are the same can the optimal light-transmitting effect be achieved. In a further alternative embodiment, the thickness of the innermost transmissive grating layer 21 is greater than the thickness of the outermost transmissive grating layer 21 because the main function of the innermost transmissive grating layer 21 is to ensure the passivation performance of the silicon substrate, so it cannot be set too thin.

[0036] In an alternative embodiment, as Figure 1 shown, the solar cell provided by the present invention further includes: a passivation layer 3 located between the anti-reflection layer 2 and the silicon substrate 1. For the material and structure of the passivation layer 3, conventional materials and structures can be selected. The present invention does not improve the passivation layer 3 itself and will not be elaborated here.

[0037] In summary, the solar cell provided by the embodiment of the present invention, by setting the anti-reflection layer as a stacked structure of multiple transmissive grating layers with different extending directions of the light-transmitting slits, enables the nano-Moiré grating structure jointly formed by the multiple transmissive grating layers to effectively increase the light-transmitting performance, especially suitable for anti-reflection materials with a refractive index lower than that of the silicon substrate. Compared with the prior art, it can better reduce light reflection while utilizing the good passivation performance of the material.

[0038] In one embodiment of the present invention, this embodiment provides a method for manufacturing a solar cell, and the manufacturing method may include: sequentially manufacturing multiple layers of transmissive grating layers 21 on at least one side in the thickness direction of the silicon substrate 1 by using plate-type atomic layer deposition, wherein each layer of transmissive grating layer 21 includes multiple parallel and spaced-apart light-transmitting slits, and the extending directions of the light-transmitting slits of the multiple layers of transmissive grating layers 21 are different.

[0039] Normally, it is necessary to first manufacture the passivation layer 3 inside the antireflection layer 2. Therefore, in a further optional embodiment, the manufacturing method provided by the present invention may be as Figure 5 shown, and includes the following steps:

[0040] Step S501, manufacturing the passivation layer 3 on at least one side in the thickness direction of the silicon substrate 1;

[0041] Step S502, sequentially manufacturing multiple layers of transmissive grating layers 21 on the outside of the passivation layer 3 by using plate-type atomic layer deposition; wherein each layer of transmissive grating layer 21 includes multiple parallel and spaced-apart light-transmitting slits, and the extending directions of the light-transmitting slits of the multiple layers of transmissive grating layers 21 are different.

[0042] Among them, plate-type atomic layer deposition is different from the original atomic layer deposition. During the plate-type atomic layer deposition process, under the purging of gases in different directions, multiple parallel and spaced-apart deposition lines will be deposited on the silicon substrate under the influence of the gas intersection, thereby forming light-transmitting slits. Therefore, only by controlling the flow rate and flow velocity of the gas purging, the width of the light-transmitting slits can be controlled.

[0043] In an optional embodiment, the specific manufacturing process of the multiple layers of transmissive grating layers 21 may be as Figure 6 shown, and includes:

[0044] Step S601, manufacturing the first layer of transmissive grating layer 21 on at least one side in the thickness direction of the silicon substrate 1 by using plate-type atomic layer deposition;

[0045] Step S602, repeatedly execute the following process until the multiple layers of transmissive grating layers 21 are obtained: rotate the placement angle of the silicon substrate 1 in the horizontal direction, and manufacture the second layer of transmissive grating layer 21 on the first layer of transmissive grating layer 21 by using plate-type atomic layer deposition.

[0046] Among them, when the passivation layer 3 is preferentially manufactured, the process of step S601 is to manufacture the first layer of transmissive grating layer 21 on the outside of the passivation layer 3 by using plate-type atomic layer deposition.

[0047] Exemplarily, the device for plate-type atomic layer deposition is as Figure 7As shown, gas is blown out from the pores at the top from top to bottom. Multiple sheet-like silicon substrates 1 can be placed on the operating table simultaneously for deposition on one side in the thickness direction of the silicon substrate 1. After step S601 is executed, the first layer of transmissive grating layer 21 with a transmissive slit extending along the main direction has been formed on the silicon substrate 1. If the preparation of the second layer of transmissive grating layer 21 continues, it cannot be distinguished from the first layer of transmissive grating layer 21. Therefore, it is necessary to rotate the placement angle of the silicon substrate 1 in the horizontal direction and perform deposition again after rotation to obtain the second layer of transmissive grating layer 21 with an extension direction different from the main direction.

[0048] When performing multiple cyclic depositions for plate-type atomic layer deposition, in any one cyclic deposition, deposition material is first introduced into the chamber at a certain flow rate so that the deposition material is deposited on the surface of the silicon substrate, and then an inert gas is introduced for purging to remove the remaining deposition material in the chamber. Finally, water vapor and an inert gas are sequentially introduced into the chamber to help the deposition material complete one cyclic deposition process under the action of water vapor. Therefore, the control of the deposition thickness of the transmissive grating layer 21 involves multiple parameters in multiple cyclic deposition processes of plate-type atomic layer deposition. Each parameter is defined below to ensure that the deposited transmissive grating layer 21 has a moderate thickness:

[0049] (1) For the deposition time of the deposition material, in an optional embodiment, the deposition time of the deposition material in each layer of transmissive grating layer 21 is 8 s to 15 s, such as 8 s, 10 s, 12 s, 15 s, etc. In the actual deposition process, one deposition cycle (loop) can usually deposit a thickness of 0.5 nm to 1 nm. Therefore, the deposition thickness of each layer of transmissive grating layer 21 can also be controlled by controlling the number of deposition cycles.

[0050] Among them, the deposition material can be at least one of trimethylaluminum, titanium tetrachloride, and zirconium tetrakis(dimethylamino), and the prepared transmissive grating layers 21 correspond to aluminum oxide, titanium dioxide, and zirconium oxide respectively.

[0051] (2) For the introduction amount of the deposition material, in an optional embodiment, the introduction amount of the deposition material in each layer of transmissive grating layer 21 during deposition is 100 sccm to 400 sccm, such as 100 sccm, 200 sccm, 300 sccm, 400 sccm, etc.

[0052] (3) For the introduction amount of the inert gas, in an optional embodiment, the introduction amount of the inert gas in each layer of transmissive grating layer 21 during deposition is 15 slm to 35 slm, such as 15 slm, 18 slm, 20 slm, 25 slm, 35 slm, etc.

[0053] (4) Regarding the introduction time of the inert gas, in an alternative embodiment, the introduction time of the inert gas in each layer of the transmissive grating layer 21 is 10 s to 20 s, such as 10 s, 12 s, 15 s, 20 s, etc. Among them, the inert gas can be nitrogen, helium, argon, etc. In the embodiments of the present invention, nitrogen is preferably used as the inert gas.

[0054] (5) Regarding the introduction amount of water vapor, in an alternative embodiment, the introduction amount of water vapor in each layer of the transmissive grating layer 21 during the deposition process is 80 sccm to 200 sccm, such as 80 sccm, 120 sccm, 150 sccm, 200 sccm, etc.

[0055] (6) Regarding the introduction time of water vapor, in an alternative embodiment, the introduction time of water vapor in each layer of the transmissive grating layer 21 is also 8 s to 15 s, such as 8 s, 10 s, 12 s, 15 s, etc.

[0056] In a further alternative embodiment, as described above, when the number of layers of the transmissive grating layer 21 is three, the thickness of the previous transmissive grating layer is not the same as that of the latter two transmissive grating layers. Therefore, there are also corresponding differences in the preparation parameters. Therefore, for the previous transmissive grating layer, the preparation parameters are specifically defined as follows:

[0057] (1) Regarding the deposition time of the deposition material, in an alternative embodiment, the deposition time of the deposition material in each layer of the transmissive grating layer 21 is 8 s to 15 s, such as 8 s, 10 s, 12 s, 15 s, etc. In the actual deposition process, a thickness of 0.5 nm to 1 nm can usually be deposited in one cycle (loop). Therefore, the deposition thickness of each layer of the transmissive grating layer 21 can also be controlled by controlling the number of deposition cycles.

[0058] (2) Regarding the introduction amount of the deposition material, in an alternative embodiment, the introduction amount of the deposition material in each layer of the transmissive grating layer 21 during the deposition process is 100 sccm to 400 sccm, such as 100 sccm, 200 sccm, 300 sccm, 400 sccm, etc.

[0059] (3) Regarding the introduction amount of the inert gas, in an alternative embodiment, the introduction amount of the inert gas in each layer of the transmissive grating layer 21 during the deposition process is 15 slm to 25 slm, such as 15 slm, 18 slm, 20 slm, 25 slm, etc.

[0060] (4) Regarding the introduction time of the inert gas, in an alternative embodiment, the introduction time of the inert gas in each layer of the transmissive grating layer 21 is 10 s to 20 s, such as 10 s, 12 s, 15 s, 20 s, etc. Among them, the inert gas can be nitrogen, helium, argon, etc. In the embodiments of the present invention, nitrogen is preferably used as the inert gas.

[0061] (5) Regarding the introduction amount of water vapor, in an alternative embodiment, the introduction amount of water vapor in each layer of the transmissive grating layer 21 during the deposition process is 80 sccm to 200 sccm, such as 80 sccm, 120 sccm, 150 sccm, 200 sccm, etc.

[0062] (6) Regarding the introduction time of water vapor, in an alternative embodiment, the introduction time of water vapor in each layer of the transmissive grating layer 21 is also 8 s to 15 s, such as 8 s, 10 s, 12 s, 15 s, etc.

[0063] Correspondingly, the preparation parameters of the latter two layers of transmissive grating layers are specifically defined as follows:

[0064] (1) Regarding the deposition time of the deposition material, in an alternative embodiment, the deposition time of the deposition material in each layer of the transmissive grating layer 21 is 8 s to 15 s, such as 8 s, 10 s, 12 s, 15 s, etc. In the actual deposition process, a thickness of 0.5 nm to 1 nm can usually be deposited in one loop, so the deposition thickness of each layer of the transmissive grating layer 21 can also be controlled by controlling the number of deposition loops.

[0065] (2) Regarding the introduction amount of the deposition material, in an alternative embodiment, the introduction amount of the deposition material in each layer of the transmissive grating layer 21 during the deposition process is 100 sccm to 200 sccm, such as 100 sccm, 120 sccm, 150 sccm, 200 sccm, etc.

[0066] (3) Regarding the introduction amount of the inert gas, in an alternative embodiment, the introduction amount of the inert gas in each layer of the transmissive grating layer 21 during the deposition process is 15 slm to 35 slm, such as 15 slm, 18 slm, 20 slm, 25 slm, 35 slm, etc.

[0067] (4) Regarding the introduction time of the inert gas, in an alternative embodiment, the introduction time of the inert gas in each layer of the transmissive grating layer 21 is 10 s to 20 s, such as 10 s, 12 s, 15 s, 20 s, etc. Among them, the inert gas can be nitrogen, helium, argon, etc. In the embodiments of the present invention, nitrogen is preferably used as the inert gas.

[0068] (5) For the throughput of water vapor, in an alternative embodiment, the throughput of water vapor during the deposition of each layer of the transmissive grating layer 21 is 80 sccm to 120 sccm, such as 80 sccm, 90 sccm, 100 sccm, 120 sccm, etc.

[0069] (6) For the introduction time of water vapor, in an alternative embodiment, the introduction time of water vapor in each layer of the transmissive grating layer 21 is also 8 s to 15 s, such as 8 s, 10 s, 12 s, 15 s, etc.

[0070] It can be seen that by controlling the above parameters, the preparation of the transmissive grating layers 21 at different positions can be realized, thereby obtaining the nano-grating structure in the embodiment of the present invention and achieving the technical effect of enhancing the sunlight transmission performance.

[0071] In addition, before performing step S501, it is also necessary to pre-treat the chamber of the plate-type atomic layer deposition, such as evacuation, leak detection, heating, etc., to ensure that the temperature of the chamber is between 250 °C and 280 °C during the deposition process, meeting the deposition requirements of the deposition material.

[0072] In summary, the preparation method of the solar cell provided by the embodiment of the present invention can effectively increase the light transmission performance by sequentially preparing multiple layers of transmissive grating layers with different directions of the light-transmitting slit extension, so that the nano-Moiré grating structure formed by the multiple layers of transmissive grating layers is particularly suitable for anti-reflection materials with a refractive index lower than that of the silicon substrate. Compared with the prior art, it can better reduce light reflection while utilizing the good passivation performance of the material.

[0073] Embodiment 1

[0074] Step a: Place the silicon substrate (silicon wafer) with a passivation layer in the carrier plate and enter the plate-type atomic layer deposition chamber with the roller. Perform processes such as evacuation, leak detection, and heating on the reaction chamber. The pressure is 5 mbar and the temperature is 260 °C; among them, the side with the passivation layer is placed horizontally upward.

[0075] Step b: Continuously introduce water vapor into the reaction chamber to pre-clean the surface of the silicon substrate. The throughput of water vapor is 200 sccm and the introduction time is 60 s.

[0076] Step c: Preparation of the innermost transmissive grating layer:

[0077] Introduce TMA (trimethylaluminum) into the chamber with a flow rate of 300 sccm for 10 s; then introduce nitrogen to purge and remove the excess TMA with a flow rate of 22 slm for 15 s; then introduce water vapor to deposit on the surface of the silicon wafer with a flow rate of 150 sccm for 10 s; finally, introduce nitrogen again for purging with a flow rate of 22 slm for 15 s to complete one cycle of deposition.

[0078] Repeat the above deposition process for multiple cycles until the thickness requirement of the innermost transmission grating layer is met.

[0079] Step d, Preparation of the transmission grating layer in the middle layer:

[0080] Rotate the silicon wafer clockwise by M° in the chamber, then introduce TMA (trimethylaluminum) to deposit on the surface of the silicon wafer with a flow rate of 150 sccm for 10 s; then introduce nitrogen for purging with a flow rate of 30 slm for 15 s; then introduce water vapor to deposit on the surface of the silicon wafer with a flow rate of 100 sccm for 10 s; finally, introduce nitrogen again for purging with a flow rate of 30 slm for 15 s to complete one cycle of deposition, thus completing the preparation of the transmission grating layer in the middle layer.

[0081] Step e, Preparation of the outermost transmission grating layer:

[0082] Continue to rotate the silicon wafer clockwise by N° in the chamber, then introduce TMA (trimethylaluminum) to deposit on the surface of the silicon wafer with a flow rate of 150 sccm for 10 s; then introduce nitrogen for purging with a flow rate of 30 slm for 15 s; then introduce water vapor to deposit on the surface of the silicon wafer with a flow rate of 100 sccm for 10 s; finally, introduce nitrogen again for purging with a flow rate of 30 slm for 15 s to complete one cycle of deposition, thus completing the preparation of the outermost transmission grating layer.

[0083] Step f, Evacuate and purge the remaining gas in the reaction chamber; backfill the chamber with nitrogen, take out the wafer, and complete the process.

[0084] Comparative Example

[0085] Step a, Place the silicon substrate (silicon wafer) with a passivation layer in the carrier plate and enter the plate-type atomic layer deposition chamber with the roller. Conduct processes such as evacuating, leak-checking, and heating the reaction chamber with a pressure of 5 mbar and a temperature of 260 °C; among them, the side with the passivation layer is placed horizontally upward.

[0086] Step b: Continuously introduce water vapor into the reaction chamber to pre-clean the surface of the silicon substrate. The flow rate of water vapor is 200 sccm, and the introduction time is 60 s.

[0087] Step c: Preparation of the antireflection layer:

[0088] Introduce TMA (trimethylaluminum) into the chamber. The flow rate of TMA is 300 sccm, and the introduction time is 10 s. Subsequently, introduce nitrogen gas to purge and remove the excess TMA. The flow rate of nitrogen gas is 22 slm, and the introduction time is 15 s. Then introduce water vapor to deposit on the surface of the silicon wafer. The flow rate of water vapor is 150 sccm, and the introduction time is 10 s. Finally, introduce nitrogen gas for purging again. The flow rate of nitrogen gas is 22 slm, and the introduction time is 15 s to complete one cycle of deposition.

[0089] Repeat the above deposition process for multiple cycles of deposition until the thickness requirement of the antireflection layer is met.

[0090] Step d: Evacuate and purge the remaining gas in the reaction chamber; backpressure the chamber with nitrogen gas, take out the wafer, and complete the process.

[0091] Among them, in Example 1 of the present invention, by sequentially setting the rotation angles M° and N° to 10° - 70° and M° = N°, different antireflection layer structures can be obtained, and different solar cells can be obtained based on different antireflection layer structures. The reflectivity of multiple solar cells obtained in Example 1 and the solar cells obtained in the comparative example are respectively detected, and the results are shown in Table 1:

[0092]

[0093] By processing the above Table 1 and taking the reflectivity of the comparative example as the benchmark, the reflectivity comparison results between Example 1 and the comparative example shown in Table 2 can be obtained:

[0094]

[0095] It can be seen from the reflectivity test results in Table 1 and the reflectivity comparison results in Table 2 that when the rotation angle of M° / N° is 10° - 70°, the reflectivity of Example 1 is less than that of the comparative example. It can be understood that the smaller the reflectivity, the more solar light is transmitted, so the transmittance is higher. Therefore, the preparation method of the solar cell provided by the embodiment of the present invention can effectively improve the transmission performance of solar light. Specifically, when the rotation angle of M° / N° changes from 10° to 30°, the reflectivity of Example 1 continuously decreases, and when the rotation angle changes from 30° to 70°, the reflectivity of Example 1 continuously increases. It can be seen that when M° / N° takes 30°, the lowest reflectivity (the highest transmittance) effect can be achieved.

[0096] In summary, in Embodiment 1 of the present invention, by setting the antireflection layer as a stacked structure of multiple transmission grating layers with different extending directions of the light-transmitting slits, the reflectivity of the antireflection layer can be effectively reduced, thereby improving the overall light conversion performance of the solar cell. Among them, it can be seen from comparing the reflectivities at different rotation angles that compared with 10°, 20° and 70°, the reflectivity decreases more significantly at 30° - 60°. Therefore, in Embodiment 1 of the present invention, it is preferably set that the included angle between the light-transmitting slits corresponding to every two adjacent transmission grating layers is 30° - 60°.

[0097] Embodiment 2

[0098] Only set M in Embodiment 1 to 30° and set N in Embodiment 1 to 10°.

[0099] Embodiment 3

[0100] Only set M in Embodiment 1 to 50° and set N in Embodiment 1 to 10°.

[0101] The reflectivities of the solar cells prepared in Embodiment 2 and Embodiment 3 are respectively detected, and the test results are shown in Table 3 below:

[0102]

[0103] It can be seen from the above results that the smaller the difference angle between every two adjacent transmission grating layers, the lower the reflectivity. Therefore, in Embodiment 1 of the present invention, it is preferably set that the included angles between the light-transmitting slits corresponding to every two adjacent transmission grating layers are the same.

[0104] The introduction provided in the above steps is only used to help understand the structure, method and core idea of the present invention. For those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and modifications can still be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A solar cell, characterized in that: include: A silicon substrate (1), and an anti-reflection layer (2) arranged on at least one side in a thickness direction of the silicon substrate (1); Wherein, the anti-reflection layer (2) comprises a plurality of transmission grating layers (21) stacked in layers; Each transmission grating layer (21) comprises a plurality of parallel and spaced light-transmitting slits; The light-transmitting slits of the multiple transmission grating layers (21) extend in different directions.

2. The solar cell according to claim 1, characterized in that: The transmission grating layer (21) comprises three layers, and the angle between the light-transmitting slits corresponding to each two adjacent layers of the transmission grating layer (21) is 10° to 70°.

3. The solar cell according to claim 2, characterized in that: The angle between the light-transmitting slits corresponding to each two adjacent transmission grating layers (21) is 30° to 60°.

4. The solar cell according to any one of claims 1 to 3, characterized in that: The angles between the light-transmitting slits corresponding to any two adjacent transmission grating layers (21) are the same.

5. The solar cell according to claim 2, characterized in that: The transmission grating layer (21) located in the middle has the same thickness as the transmission grating layer (21) located on the outermost side; and / or, The thickness of the transmission grating layer (21) located at the innermost side is greater than the thickness of the transmission grating layer (21) located at the outermost side.

6. The solar cell according to claim 2, characterized in that: The transmission grating layer (21) located at the innermost side has a thickness of 1.5 nm to 5 nm; and / or, The transmission grating layer (21) located in the middle has a thickness of 0.5 nm to 2 nm; and / or, The thickness of the transmission grating layer (21) located on the outermost side is 0.5 nm to 2 nm.

7. The solar cell according to claim 1, 2, 5 or 6, characterized in that: The thickness of the anti-reflection layer (2) is 3.5 nm to 7 nm.

8. A method for preparing a solar cell, characterized in that: include: A multilayer transmission grating layer (21) is sequentially prepared on at least one side of the silicon substrate (1) in the thickness direction by using a plate-type atomic layer deposition method, Each layer of the transmission grating layer (21) comprises a plurality of parallel and spaced light-transmitting slits, and the light-transmitting slits of the multiple layers of the transmission grating layer (21) extend in different directions.

9. The preparation method according to claim 8, characterized in that: The multi-layer transmission grating layer (21) comprises the following specific preparation steps: Using a plate-type atomic layer deposition method to prepare a first transmission grating layer (21) on at least one side in the thickness direction of the silicon substrate (1); The following process is cyclically performed until a plurality of transmission grating layers (21) are obtained: the placement angle of the silicon substrate (1) is rotated in the horizontal direction, and a second transmission grating layer (21) is prepared on the first transmission grating layer (21) by using a plate-type atomic layer deposition method.

10. The preparation method according to claim 8, characterized in that: The deposition time of the deposited material in each transmission grating layer (21) is 8s to 15s; and / or, During the deposition process of each transmission grating layer (21), the amount of deposition material introduced is 100 sccm to 400 sccm; and / or, During the deposition process of each transmission grating layer (21), the amount of inert gas introduced is 15 slm to 35 slm.

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