Solar cell

Abstract

The utility model discloses a solar cell, which relates to the technical field of solar cell manufacture, and comprises a silicon substrate and an anti-reflection layer arranged on at least one side of the thickness direction of the silicon substrate. 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 utility model relates to solar cell manufacturing technical field especially relates to a solar cell. BACKGROUND

[0002] In the existing solar cell structure, it is usually necessary to set antireflection layer on the side of incident light to reduce the reflection of incident sunlight, so that more sunlight is incident into the silicon substrate, and the light conversion performance of the solar cell is increased. Specifically, the existing antireflection layer often utilizes the size relationship between the refractive index, and by inserting the antireflection layer with the refractive index N1 between the two layers of medium with the refractive index N0 (air) and N2 (silicon substrate), the reflectivity is gradually reduced. However, for materials such as aluminum oxide which have excellent passivation performance, the refractive index is often lower than that of the silicon substrate (N2), resulting in that part of the sunlight is still reflected, and excellent antireflection effect cannot be achieved. SUMMARY

[0003] Therefore, the utility model embodiment provides a solar cell, by setting the antireflection layer as the laminated structure of multiple transmission grating layers with different extension directions of light transmission slits, the nano-Mor grating structure formed by the multiple transmission grating layers can effectively increase the transmission performance of light, especially for the antireflection material with lower refractive index than the silicon substrate, compared with the prior art, the material passivation performance can be utilized, and the light reflection can be better reduced.

[0004] In order to solve the above technical problems, the utility model provides the following technical scheme:

[0005] In the first aspect, the utility model provides a solar cell, which comprises a silicon substrate, an antireflection layer arranged on at least one side of the silicon substrate in the thickness direction, wherein the antireflection layer comprises multiple transmission grating layers arranged in layers, each transmission grating layer comprises multiple parallel and spaced light transmission slits, and the extension directions of the light transmission 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 transmission slits corresponding to each adjacent two transmission grating layers is 10°-70°.

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

[0008] Optionally, the included angles between the light transmission slits corresponding to any adjacent two transmission grating layers are the same.

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

[0010] Optionally, the thickness of the transmission grating layer located at the innermost side is 1.5nm-5nm;

[0011] Optionally, the thickness of the transmission grating layer located in the middle is 0.5nm-2nm;

[0012] Optionally, the thickness of the transmission grating layer located at the outermost side is 0.5nm-2nm.

[0013] Optionally, the thickness of the antireflection layer is 3.5nm-7nm.

[0014] The technical scheme of the first aspect of the above-mentioned utility model has the following advantages or beneficial effects: by setting the antireflection layer as a laminated structure of multiple transmission grating layers with different light transmission slit extension directions, the nano-Moiré grating structure formed by the multiple transmission grating layers can effectively increase the transmission performance of light, especially for the antireflection material with a refractive index lower than the silicon substrate, compared with the prior art, the material can be better passivated while the light reflection is better reduced. BRIEF DESCRIPTION OF DRAWINGS

[0015] The accompanying drawings are used to better understand the utility model and do not constitute improper limitations on the utility model. Among them:

[0016] Figure 1 is a sectional structure schematic diagram of a solar cell according to an embodiment of the utility model;

[0017] Figure 2 is a laminated structure schematic diagram of a transmission grating layer according to an embodiment of the utility model;

[0018] Figure 3 is another laminated structure schematic diagram of a transmission grating layer according to an embodiment of the utility model;

[0019] Figure 4 is still another laminated structure schematic diagram of a transmission grating layer according to an embodiment of the utility model;

[0020] Figure 5 is a main flow schematic diagram of a preparation method of a solar cell according to an embodiment of the utility model;

[0021] Figure 6 is a main flow schematic diagram of preparing multiple transmission grating layers according to an embodiment of the utility model;

[0022] Figure 7It is a schematic diagram of a plate type atomic layer deposition device according to the embodiment of the utility model.

[0023] The reference signs are as follows:

[0024] 1-silicon substrate; 2-anti-reflection layer; 21-transmission grating layer; 3-passivation layer. DETAILED DESCRIPTION

[0025] The solar cell is a kind of photovoltaic semiconductor wafer using sunlight to generate electricity, also called "solar chip" or "photocell", it can output voltage and produce current in the case of loop instantaneously as long as being illuminated by light of certain illumination condition.In physics, it is called solar photovoltaic (Photovoltaic, abbreviated as PV), simply called photovoltaic.In order to facilitate and clearly describe the preparation method of solar cell and solar cell of the utility model, the exemplary embodiments of the utility model are described below in conjunction with the drawings, including various details of the embodiments of the utility model to help understanding, they should be considered only as exemplary.Therefore, those skilled in the art should realize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the utility model.Similarly, in order to be clear and concise, the description is omitted in the following description.

[0026] Figure 1 The cross-sectional structure schematic diagram of the solar cell provided by the embodiment of the utility model is shown, as Figure 1 As shown, the solar cell provided by the utility model comprises a silicon substrate 1, an anti-reflection layer 2 arranged on at least one side of the silicon substrate 1 in the thickness direction;Wherein, the anti-reflection layer 2 comprises a plurality of transmission grating layers 21 arranged in layers;Each transmission grating layer 21 comprises a plurality of parallel and spaced light transmission slits;The extension direction of the light transmission slits of the plurality of transmission grating layers 21 is different.

[0027] It can be understood that for each transmission grating layer 21, a plurality of parallel and spaced light transmission slits can decompose incident sunlight into different wavelengths of spectrum by diffraction effect, when the frequency of incident photon matches the vibration frequency of free electron on the surface of nanostructure, nano-particle will have strong absorption effect on incident photon, so that local surface ion resonance phenomenon occurs.Therefore, the embodiment of the utility model utilizes this principle, adjusts the extension angle of light transmission slit between the plurality of transmission grating layers 21, so that the nano-grating structure formed by the plurality of transmission grating layers 21 can match the frequency of incident sunlight, thereby improving the absorption efficiency of sunlight.Specifically, from Figure 1 It can be seen that each transmission grating layer 21 is composed of a plurality of parallel and spaced light transmission slits, and the extension direction of the plurality of transmission grating layers 21 is different.

[0028] In an alternative embodiment, the transmission grating layer 21 is three layers, and the included angle between the light transmission slits corresponding to each adjacent two layers of the transmission grating layer 21 is 10°-70°, such as 10°, 20°, 30°, 40°, 50°, 60°, and 70°, etc. Still taking the example of Figure 1 When the transmission grating layer 21 is three layers, the included angle between the innermost transmission grating layer 21 and the middle transmission grating layer 21, and the middle transmission grating layer 21 and the outermost transmission grating layer 21 are all 10°-70°. Among them, for the direction of the included angle between any adjacent two layers of the transmission grating layer 21, as long as the extension direction of the light transmission slits of the multi-layer transmission grating layer 21 is different, it does not necessarily limit the direction of the included angle to be the same.

[0029] Exemplarily, as shown in Figure 2 Taking the extension direction of the light transmission slit of the innermost transmission grating layer 21 as the main direction, the extension direction of the light transmission slit of the middle transmission grating layer 21 can be 70° (i.e. the first direction) to the left of the main direction, and further, the extension direction of the light transmission slit of the outermost transmission grating layer 21 can be 30° (i.e. the second direction) to the right of the first direction, thereby obtaining the three-layer transmission grating layer 21 with different extension directions under the perspective angle.

[0030] Exemplarily, as shown in Figure 3 Still taking the extension direction of the light transmission slit of the innermost transmission grating layer 21 as the main direction, the extension direction of the light transmission slit of the middle transmission grating layer 21 can be 40° (i.e. the first direction) to the left of the main direction, and then continue to rotate 30° to the left on the basis of the first direction to obtain the outermost transmission grating layer 21. Although Figure 3 and Figure 2 The grating structures obtained in the perspective direction are the same, but due to the actual difference in the direction and angle of the included angle between the adjacent transmission grating layers 21, the final absorption effect of sunlight will also have some differences.

[0031] It is worth mentioning that the number of layers of the transmission grating layer 21 is not limited to three layers, and can be other layers more than three layers. In the embodiment of the utility model, the innermost transmission grating layer 21 ensures the overall passivation performance of the solar cell, and the other layers of transmission grating layer 21 (such as the transmission grating layer 21 in the middle of the three layers and the transmission grating layer 21 at the outermost side) mainly undertake the function of forming the nano-grating structure, therefore, when the number of layers of the transmission grating layer 21 is N, the passivation performance to the silicon substrate can be ensured by the first N-2 layers of transmission grating layer 21 at the inner side, and the absorption performance to the sunlight can be improved by controlling the extension direction and the extension angle between the N-1 layer and the N layer of transmission grating layer 21. It is worth mentioning here that each layer of transmission grating layer 21 is deposited by one or more deposition cycles, and for a single transmission grating layer 21, there is no position transformation between the plurality of deposition cycles, that is, the deposition direction of one or more deposition cycles in a single transmission grating layer 21 is the same. Exemplarily, taking the three layers of transmission grating layer 21 as an example, the innermost transmission grating layer 21 can be deposited by 5 deposition cycles, and the transmission grating layer 21 in the middle and the transmission grating layer 21 at the outermost side can be deposited by 1 deposition cycle.

[0032] In a further optional embodiment, through the continuous adjustment test of the inventor for the included angle between the light transmission slits corresponding to the adjacent two layers of transmission grating layer 21, the utility model embodiment sets the included angle between the light transmission slits corresponding to each adjacent two layers of transmission grating layer 21 to 30°-60°, such as 30°, 40°, 50° and 60°. Compared with the included angle of 10°-70°, setting the included angle to 30°-60° can better improve the absorption performance of the multilayer transmission grating layer 21 to the sunlight.

[0033] In a further optional embodiment, the included angle between the light transmission slits corresponding to any adjacent two layers of transmission grating layer 21 is the same. It can be understood that, since the extension direction of the light transmission slit of the multilayer transmission grating layer 21 is different in the embodiment of the utility model, when the included angle between the light transmission slits corresponding to any adjacent two layers of transmission grating layer 21 is the same, the rotation direction of the plurality of transmission grating layers 21 is the same (such as Figure 3 indicated), that is, the overlapping of the multilayer transmission grating layer 21 after rotation is avoided (such as Figure 4 indicated). Specifically, in Figure 4In this embodiment, the middle transmission grating layer 21 (first direction) is obtained by rotating 30° to the left in the main direction of the innermost transmission grating layer 21, while the outermost transmission grating layer 21 is obtained by rotating 30° to the right in the first direction. This results in the outermost transmission grating layer 21 actually overlapping with the innermost transmission grating layer 21, weakening the nanograting structure composed of multiple 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 this embodiment, when the included angle between the light-transmitting slits corresponding to any two adjacent transmission grating layers 21 is the same, the rotation direction of multiple transmission grating layers 21 is the same, so as to avoid the overlap of multiple transmission grating layers 21 as much as possible and improve the transmission performance.

[0034] The thickness of the antireflection layer 2 is typically controlled by the number of deposition cycles in the deposition process. In practical applications, the thickness should be sufficient to reduce sunlight reflection, and should not be too thick or too thin. Generally, the thickness deposited in one deposition cycle is 0.5 nm to 1 nm. Therefore, in an optional embodiment of this invention, the thickness of the antireflection layer 2 is 3.5 nm to 7 nm, such as 3.5 nm, 5 nm, 6 nm, or 7 nm, obtained through multiple deposition cycles. It is understood that the multiple deposition cycles correspond to the total thickness of the antireflection 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, a 3+2+2 allocation method can also be used. That is, the innermost transmission grating layer 21 can be deposited for 3 deposition cycles, while the middle and outermost transmission grating layers can be deposited for 2 deposition cycles. It should be noted that if the thickness of the antireflective layer 2 is set too thick, it not only wastes materials but also increases the difficulty of the process, which is not conducive to industrial manufacturing. On the other hand, if the thickness of the antireflective layer 2 is set too thin, it will affect the antireflection effect and reduce the conversion efficiency of sunlight.

[0035] In one optional embodiment, the thickness of the innermost transmission grating layer 21 is 1.5nm to 5nm, such as 1.5nm, 2nm, 2.2nm, 2.5nm, 3nm, 5nm, etc.; the thickness of the middle transmission grating layer 21 is 0.5nm to 2nm, such as 0.5nm, 1nm, 1.2nm, 1.4nm, 1.5nm, 2nm, etc.; and the thickness of the outermost transmission grating layer 21 is 0.5nm to 2nm, such as 0.5nm, 1nm, 1.2nm, 1.4nm, 1.5nm, 2nm, etc. Understandably, since the purpose of the innermost transmission grating layer 21 is to ensure passivation performance, the innermost transmission grating layer 21 needs to be relatively thick. The transmission grating layer 21 in the middle and the transmission grating layer 21 in the outermost position together form a nanograting. Through continuous experiments, the inventors discovered that different thicknesses and different extension directions of the light-transmitting slits will have different effects on the transmission of sunlight. Making the thickness of the transmission grating layers 21 in the middle and outer positions relatively thinner can be more conducive to the downward transmission of sunlight.

[0036] In a further optional embodiment, the thickness of the middle transmission grating layer 21 is the same as that of the outermost transmission grating layer 21. This is because transmission grating layers 21 with different thicknesses will affect the light transmission performance of the formed nanograting structure. Only when the thicknesses of two adjacent transmission grating layers 21 are the same can the optimal light transmission effect be achieved. In a further optional embodiment, the thickness of the innermost transmission grating layer 21 is greater than that of the outermost transmission grating layer 21. This is because the main function of the innermost transmission grating layer 21 is to ensure the passivation performance of the silicon substrate, and therefore it cannot be made too thin.

[0037] In one alternative embodiment, such as Figure 1 As shown, the solar cell provided by this utility model further includes a passivation layer 3 located between the antireflection layer 2 and the silicon substrate 1. Conventional materials and structures can be selected for the passivation layer 3; this utility model does not modify the passivation layer 3 itself, and will not be described in detail here.

[0038] In summary, the solar cell provided by this utility model embodiment, by setting the antireflection layer as a stacked structure of multiple transmission grating layers with different extension directions of the light-transmitting slits, can effectively increase the light transmission performance of the nanomoir grating structure formed by the multiple transmission grating layers. It is especially suitable for antireflection materials with a refractive index lower than that of silicon substrate. Compared with the prior art, it can better reduce light reflection while utilizing the good passivation performance of the material.

[0039] In one embodiment of the present invention, a method for fabricating a solar cell is provided. The method may include: sequentially fabricating multiple transmission grating layers 21 on at least one side of a silicon substrate 1 in the thickness direction using a plate atomic layer deposition method. Each transmission grating layer 21 includes multiple parallel and spaced light-transmitting slits, and the extension directions of the light-transmitting slits of the multiple transmission grating layers 21 are different.

[0040] Typically, a passivation layer 3 needs to be prepared inside the antireflection layer 2 first. Therefore, in a further optional embodiment, the preparation method provided by this invention can be as follows: Figure 5 As shown, it includes the following steps:

[0041] Step S501: A passivation layer 3 is prepared on at least one side of the silicon substrate 1 in the thickness direction;

[0042] In step S502, multiple transmission grating layers 21 are sequentially prepared on the outside of the passivation layer 3 using plate atomic layer deposition method; wherein each transmission grating layer 21 includes multiple parallel and spaced light-transmitting slits, and the extension directions of the light-transmitting slits of the multiple transmission grating layers 21 are different.

[0043] Plate-type atomic layer deposition differs from traditional atomic layer deposition. During plate-type atomic layer deposition, the silicon substrate is purged by gases from different directions. Under the influence of the interlacing gases, multiple parallel and spaced deposition lines are deposited, forming a light-transmitting slit. Therefore, the width of the light-transmitting slit can be controlled simply by adjusting the flow rate and velocity of the gas purging.

[0044] In an optional embodiment, the specific fabrication process of the multilayer transmission grating layer 21 can be as follows: Figure 6 As shown, it includes:

[0045] Step S601: A first transmission grating layer 21 is prepared on at least one side of the silicon substrate 1 in the thickness direction using a plate atomic layer deposition method.

[0046] Step S602, repeat the following process until a multilayer transmission grating layer 21 is obtained: rotate the placement angle of the silicon substrate 1 in the horizontal direction, and prepare a second transmission grating layer 21 on the first transmission grating layer 21 using a plate atomic layer deposition method.

[0047] When the passivation layer 3 is prepared first, step S601 involves preparing the first transmission grating layer 21 on the outside of the passivation layer 3 using a plate atomic layer deposition method.

[0048] Exemplary examples include apparatus for plate atomic layer deposition such as Figure 7As shown, gas is blown out from the top vent from top to bottom. Multiple sheet-like silicon substrates 1 can be placed simultaneously on the operating table for deposition on one side of the silicon substrate 1 in the thickness direction. After step S601 is performed, a first transmission grating layer 21 with light-transmitting slits extending in the main direction has been formed on the silicon substrate 1. If the fabrication of the second transmission grating layer 21 continues, it will be indistinguishable from the first transmission 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 a second transmission grating layer 21 with an extension direction different from the main direction.

[0049] In plate-type atomic layer deposition (ALD) with multiple deposition cycles, each cycle begins by introducing deposition material into the chamber at a certain flow rate to deposit it onto the silicon substrate surface. Then, inert gas is introduced to purge any remaining deposition material from the chamber. Finally, water vapor and inert gas are sequentially introduced into the chamber to aid in the deposition process under the influence of the water vapor. Therefore, controlling the thickness of the transmission grating layer 21 involves multiple parameters in the multiple deposition cycles of plate-type ALD. The following sections define limits for each parameter to ensure a suitable thickness for the deposited transmission grating layer 21:

[0050] (1) Regarding the deposition time of the deposited material, in one optional embodiment, the deposition time of the deposited material in each transmission grating layer 21 is 8s to 15s, such as 8s, 10s, 12s, 15s, etc. In the actual deposition process, one deposition cycle can usually deposit a thickness of 0.5nm to 1nm, so the deposition thickness of each transmission grating layer 21 can also be controlled by controlling the number of deposition cycles.

[0051] The deposition material can be at least one of trimethylaluminum, titanium tetrachloride and tetra(dimethylamino)zirconia, and the prepared transmission grating layer 21 corresponds to alumina, titanium dioxide and zirconium oxide respectively.

[0052] (2) Regarding the amount of deposited material introduced, in one optional embodiment, the amount of deposited material introduced into each transmission grating layer 21 during the deposition process is 100 sccm ~ 400 sccm, for example 100 sccm, 200 sccm, 300 sccm, 400 sccm, etc.

[0053] (3) Regarding the amount of inert gas introduced, in one optional embodiment, the amount of inert gas introduced during the deposition process of each transmission grating layer 21 is 15 slm to 35 slm, for example, 15 slm, 18 slm, 20 slm, 25 slm, 35 slm, etc.

[0054] (4) Regarding the inert gas introduction time, in one optional embodiment, the inert gas introduction time in each transmission grating layer 21 is 10s~20s, for example 10s, 12s, 15s, 20s, etc. The inert gas can be nitrogen, helium, argon, etc., and nitrogen is preferred as the inert gas in this embodiment of the present invention.

[0055] (5) Regarding the amount of water vapor introduced, in one optional embodiment, the amount of water vapor introduced during the deposition process of each transmission grating layer 21 is 80 sccm ~ 200 sccm, for example 80 sccm, 120 sccm, 150 sccm, 200 sccm, etc.

[0056] (6) Regarding the water vapor introduction time, in one optional embodiment, the water vapor introduction time in each transmission grating layer 21 is also 8s~15s, such as 8s, 10s, 12s, 15s, etc.

[0057] In a further optional embodiment, as mentioned above, when the number of transmission grating layers 21 is three, the thickness of the first transmission grating layer is not the same as the thickness of the last two transmission grating layers. Therefore, the fabrication parameters also differ accordingly. Thus, for the first transmission grating layer, the fabrication parameters are specifically limited as follows:

[0058] (1) Regarding the deposition time of the deposited material, in one optional embodiment, the deposition time of the deposited material in each transmission grating layer 21 is 8s to 15s, such as 8s, 10s, 12s, 15s, etc. In the actual deposition process, a thickness of 0.5nm to 1nm can usually be deposited in one cycle, so the deposition thickness of each transmission grating layer 21 can also be controlled by controlling the number of deposition cycles.

[0059] (2) Regarding the amount of deposited material introduced, in one optional embodiment, the amount of deposited material introduced into each transmission grating layer 21 during the deposition process is 100 sccm ~ 400 sccm, for example 100 sccm, 200 sccm, 300 sccm, 400 sccm, etc.

[0060] (3) Regarding the amount of inert gas introduced, in one optional embodiment, the amount of inert gas introduced during the deposition process of each transmission grating layer 21 is 15 slm to 25 slm, for example, 15 slm, 18 slm, 20 slm, 25 slm, etc.

[0061] (4) Regarding the inert gas introduction time, in one optional embodiment, the inert gas introduction time in each transmission grating layer 21 is 10s~20s, for example 10s, 12s, 15s, 20s, etc. The inert gas can be nitrogen, helium, argon, etc., and nitrogen is preferred as the inert gas in this embodiment of the present invention.

[0062] (5) Regarding the amount of water vapor introduced, in one optional embodiment, the amount of water vapor introduced during the deposition process of each transmission grating layer 21 is 80 sccm ~ 200 sccm, for example 80 sccm, 120 sccm, 150 sccm, 200 sccm, etc.

[0063] (6) Regarding the water vapor introduction time, in one optional embodiment, the water vapor introduction time in each transmission grating layer 21 is also 8s~15s, such as 8s, 10s, 12s, 15s, etc.

[0064] Correspondingly, the fabrication parameters for the latter two transmission grating layers are specifically limited as follows:

[0065] (1) Regarding the deposition time of the deposited material, in one optional embodiment, the deposition time of the deposited material in each transmission grating layer 21 is 8s to 15s, such as 8s, 10s, 12s, 15s, etc. In the actual deposition process, a thickness of 0.5nm to 1nm can usually be deposited in one cycle, so the deposition thickness of each transmission grating layer 21 can also be controlled by controlling the number of deposition cycles.

[0066] (2) Regarding the amount of deposited material introduced, in one optional embodiment, the amount of deposited material introduced into each transmission grating layer 21 during the deposition process is 100 sccm ~ 200 sccm, for example 100 sccm, 120 sccm, 150 sccm, 200 sccm, etc.

[0067] (3) Regarding the amount of inert gas introduced, in one optional embodiment, the amount of inert gas introduced during the deposition process of each transmission grating layer 21 is 15 slm to 35 slm, for example, 15 slm, 18 slm, 20 slm, 25 slm, 35 slm, etc.

[0068] (4) Regarding the inert gas introduction time, in one optional embodiment, the inert gas introduction time in each transmission grating layer 21 is 10s~20s, for example 10s, 12s, 15s, 20s, etc. The inert gas can be nitrogen, helium, argon, etc., and nitrogen is preferred as the inert gas in this embodiment of the present invention.

[0069] (5) Regarding the amount of water vapor introduced, in one optional embodiment, the amount of water vapor introduced during the deposition process of each transmission grating layer 21 is 80 sccm ~ 120 sccm, for example 80 sccm, 90 sccm, 100 sccm, 120 sccm, etc.

[0070] (6) Regarding the water vapor introduction time, in one optional embodiment, the water vapor introduction time in each transmission grating layer 21 is also 8s~15s, such as 8s, 10s, 12s, 15s, etc.

[0071] As can be seen, by controlling the above parameters, the transmission grating layer 21 located at different positions can be prepared, thereby obtaining the nano grating structure in the embodiment of this utility model and achieving the technical effect of enhancing the transmission performance of sunlight.

[0072] In addition, before performing step S501, the chamber for plate atomic layer deposition needs to be pretreated, such as by vacuuming, leak detection, and heating, to ensure that the temperature of the chamber is between 250°C and 280°C during the deposition process, so as to meet the deposition requirements of the deposition material.

[0073] In summary, the method for preparing a solar cell provided by this utility model, by sequentially preparing multiple transmission grating layers with different extension directions of the light-transmitting slits, enables the nanomoiré grating structure formed by the multiple transmission grating layers to effectively increase the light transmission performance. It is especially suitable for antireflective materials with a refractive index lower than that of silicon substrates. Compared with the prior art, it can better reduce light reflection while utilizing the good passivation properties of the material.

[0074] Example 1

[0075] Step a: Place the silicon substrate (silicon wafer) with the passivation layer inside the carrier plate. As the rollers enter the plate atomic layer deposition chamber, the reaction chamber is subjected to processes such as vacuuming, leak detection, and heating. The pressure is 5 mbar and the temperature is 260℃. The side with the passivation layer is placed horizontally upward.

[0076] Step b: Water vapor is continuously introduced into the reaction chamber to pre-clean the surface of the silicon substrate. The water vapor introduction rate is 200 sccm and the introduction time is 60 s.

[0077] Step c, fabrication of the innermost transmission grating layer:

[0078] TMA (trimethylaluminum) was introduced into the chamber at a flow rate of 300 sccm for 10 s. Excess TMA was then removed by purging with nitrogen at a flow rate of 22 slm for 15 s. Next, water vapor was introduced to deposit on the silicon wafer surface at a flow rate of 150 sccm for 10 s. Finally, nitrogen was purged again at a flow rate of 22 slm for 15 s, completing one deposition cycle.

[0079] Repeat the above deposition process multiple times until the required thickness of the innermost transmission grating layer is achieved.

[0080] Step d: Fabrication of the transmission grating layer located in the intermediate layer:

[0081] The silicon wafer is rotated clockwise by M° in the chamber, and then TMA (trimethylaluminum) is introduced and deposited on the silicon wafer surface at a flow rate of 150 sccm for 10 s. Nitrogen gas is then introduced for purging at a flow rate of 30 slm for 15 s. Water vapor is then introduced and deposited on the silicon wafer surface at a flow rate of 100 sccm for 10 s. Finally, nitrogen gas is introduced again for purging at a flow rate of 30 slm for 15 s, completing one cycle of deposition and thus completing the fabrication of the transmission grating layer located in the intermediate layer.

[0082] Step e, fabrication of the outermost transmission grating layer:

[0083] The silicon wafer is rotated clockwise by N° in the chamber, and then TMA (trimethylaluminum) is introduced and deposited on the silicon wafer surface at a flow rate of 150 sccm for 10 s. Nitrogen gas is then introduced for purging at a flow rate of 30 slm for 15 s. Water vapor is then introduced and deposited on the silicon wafer surface at a flow rate of 100 sccm for 10 s. Finally, nitrogen gas is introduced again for purging at a flow rate of 30 slm for 15 s, completing one cycle of deposition and thus fabricating the outermost transmission grating layer.

[0084] Step f: Evacuate and purge the remaining gas in the reaction chamber; fill the chamber with nitrogen and pressurize it back; remove the wafer to complete the process.

[0085] Comparative Example

[0086] Step a: Place the silicon substrate (silicon wafer) with the passivation layer inside the carrier plate. As the rollers enter the plate atomic layer deposition chamber, the reaction chamber is subjected to processes such as vacuuming, leak detection, and heating. The pressure is 5 mbar and the temperature is 260℃. The side with the passivation layer is placed horizontally upward.

[0087] Step b: Water vapor is continuously introduced into the reaction chamber to pre-clean the surface of the silicon substrate. The water vapor introduction rate is 200 sccm and the introduction time is 60 s.

[0088] Step c, Preparation of the antireflection layer:

[0089] TMA (trimethylaluminum) was introduced into the chamber at a flow rate of 300 sccm for 10 s. Excess TMA was then removed by purging with nitrogen at a flow rate of 22 slm for 15 s. Next, water vapor was introduced to deposit on the silicon wafer surface at a flow rate of 150 sccm for 10 s. Finally, nitrogen was purged again at a flow rate of 22 slm for 15 s, completing one deposition cycle.

[0090] Repeat the above deposition process multiple times until the required antireflection layer thickness is achieved.

[0091] Step d: Evacuate and purge the remaining gas in the reaction chamber; fill the chamber with nitrogen and pressurize it back; remove the wafer to complete the process.

[0092] In Embodiment 1 of this invention, by setting the rotation angles M° and N° sequentially to 10°~70° with M°=N°, different antireflection layer structures can be obtained, and different solar cells can be obtained based on the different antireflection layer structures. The reflectivity of multiple solar cells obtained in Embodiment 1 and the solar cell obtained in the comparative example was measured, and the results are shown in Table 1.

[0093]

[0094] By processing Table 1 above and using the reflectance of the comparative example as a benchmark, we can obtain the reflectance comparison results between Example 1 and the comparative example shown in Table 2:

[0095]

[0096] As can be seen from the reflectivity test results in Table 1 and the reflectivity comparison results in Table 2, when the rotation angle of M° / N° is between 10° and 70°, the reflectivity of Example 1 is always lower than that of the comparative example. It is understood that a lower reflectivity indicates more transmitted sunlight, and therefore a higher transmittance. Thus, the solar cell fabrication method provided by this invention can effectively improve the transmission performance of sunlight. Specifically, as the rotation angle of M° / N° changes from 10° to 30°, the reflectivity of Example 1 continuously decreases, and as the rotation angle changes from 30° to 70°, the reflectivity of Example 1 continuously increases. It is evident that when M° / N° is 30°, the effect of the lowest reflectivity (highest transmittance) can be achieved.

[0097] In summary, Embodiment 1 of this utility model effectively reduces the reflectivity of the antireflection layer by setting it as a stacked structure of multiple transmission grating layers with different extension directions of the light-transmitting slits, thereby improving the overall light conversion performance of the solar cell. Specifically, comparing the reflectivity at different rotation angles shows that the reflectivity reduction is more significant at 30°~60° compared to 10°, 20°, and 70°. Therefore, this embodiment of the utility model preferably sets the included angle between the light-transmitting slits corresponding to each adjacent pair of transmission grating layers to 30°~60°.

[0098] Example 2

[0099] Only M in Example 1 is set to 30°, and N in Example 1 is set to 10°.

[0100] Example 3

[0101] Only M in Example 1 is set to 50°, and N in Example 1 is set to 10°.

[0102] The reflectivity of the solar cells prepared in Examples 2 and 3 was measured, and the test results are shown in Table 3 below:

[0103]

[0104] As can be seen from the above results, the smaller the angle difference between two adjacent transmission grating layers, the lower the reflectivity. Therefore, in this embodiment of the invention, it is preferable to set the included angle between the light-transmitting slits corresponding to two adjacent transmission grating layers to be the same.

[0105] The above steps are provided only to help understand the structure, method, and core idea of ​​this utility model. For those skilled in the art, various improvements and modifications can be made to this utility model without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims of this utility model.

Claims

1. A solar cell, characterized in that, include: Silicon substrate (1), antireflection layer (2) disposed on at least one side in the thickness direction of the silicon substrate (1); The antireflection layer (2) includes a multilayer transmission grating layer (21) stacked together. Each of the aforementioned transmission grating layers (21) includes multiple parallel and spaced-apart light-transmitting slits; The light-transmitting slits of the multilayer transmission grating layer (21) extend in different directions.

2. The solar cell according to claim 1, characterized in that, The transmission grating layer (21) consists of three layers, and the angle between the light-transmitting slits corresponding to each two adjacent transmission grating layers (21) is 10°~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°~60°.

4. The solar cell according to any one of claims 1-3, characterized in that, The angle between the light-transmitting slits corresponding to any two adjacent transmission grating layers (21) is 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 innermost transmission grating layer (21) is greater than the thickness of the outermost transmission grating layer (21).

6. The solar cell according to claim 2, characterized in that, The thickness of the innermost transmission grating layer (21) is 1.5 nm to 5 nm.

7. The solar cell according to claim 2, characterized in that, The thickness of the transmission grating layer (21) located in the middle is 0.5nm~2nm.

8. The solar cell according to claim 2, characterized in that, The thickness of the outermost transmission grating layer (21) is 0.5 nm to 2 nm.

9. The solar cell according to claim 5, characterized in that, The thickness of the innermost transmission grating layer (21) is 1.5 nm to 5 nm; The thickness of the transmission grating layer (21) located in the middle is 0.5nm~2nm; The thickness of the outermost transmission grating layer (21) is 0.5 nm to 2 nm.

10. The solar cell according to any one of claims 1-3 and 5-9, characterized in that, The thickness of the antireflection layer (2) is 3.5 nm to 7 nm.

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