Preparation method of photovoltaic cell and photovoltaic cell

Abstract

The invention relates to a preparation method of a photovoltaic cell and the photovoltaic cell, and the preparation method comprises the steps: preparing a substrate which comprises a first surface and a second surface which are opposite to each other, and the first surface is of a textured structure; placing the substrate into an ALD (atomic layer deposition) chamber; sequentially depositing an aluminum-silicon layer and an aluminum oxide layer on the first surface; putting the substrate with the aluminum-silicon layer and the aluminum oxide layer into a PECVD (Plasma Enhanced Chemical Vapor Deposition) deposition chamber; depositing a silicon nitride layer on the aluminum oxide layer; introducing ammonia gas into the PECVD deposition chamber, starting a radio frequency power supply, and ionizing hydrogen ions in the ammonia gas; and diffusing the hydrogen ions to the aluminum-silicon layer. The aluminum-silicon layer forms an aluminum-silicon bond on the first surface of the substrate, hydrogen ions are diffused to the aluminum-silicon layer to form an aluminum-hydrogen bond, when ultraviolet light irradiates the surface of the photovoltaic cell, the aluminum-hydrogen bond can reduce the possibility that the silicon-hydrogen bond on the surface of the silicon layer is damaged by the ultraviolet light, the chemical passivation loss of the photovoltaic cell is reduced, and then the conversion efficiency is improved.

Description

Technical Field

[0001] The present application relates to the field of solar power generation technology, and specifically to a method for preparing a photovoltaic cell and a photovoltaic cell. Background Art

[0002] Photovoltaic cells convert absorbed sunlight into electrical energy through the photoelectric effect. With long-term use, photovoltaic cells are prone to attenuation under ultraviolet light, resulting in a decrease in the electrical performance of the photovoltaic cells and a decrease in the photoelectric conversion efficiency, which in turn affects the overall power generation capacity of the photovoltaic cells. Summary of the invention

[0003] In view of this, the present application provides a method for preparing a photovoltaic cell and a photovoltaic cell to solve the problem that the photovoltaic cell is prone to attenuation under ultraviolet light.

[0004] In a first aspect, the present application provides a method for preparing a photovoltaic cell, the method comprising:

[0005] Prepare a substrate, the substrate comprising a first surface and a second surface opposite to each other, the first surface having a suede structure;

[0006] placing the substrate into an ALD deposition chamber;

[0007] Depositing an aluminum silicon layer and an aluminum oxide layer in sequence on the first surface;

[0008] placing the substrate with the aluminum silicon layer and the aluminum oxide layer into a PECVD deposition chamber;

[0009] depositing a silicon nitride layer on the aluminum oxide layer;

[0010] Introducing ammonia gas into the PECVD deposition chamber, turning on the radio frequency power supply, and ionizing hydrogen ions in the ammonia gas;

[0011] The hydrogen ions are diffused into the aluminum silicon layer.

[0012] In a possible embodiment, when an aluminum silicon layer and an aluminum oxide layer are sequentially deposited on the first surface, the preparation method includes:

[0013] First, 18 sccm to 22 sccm of water vapor is introduced into the ALD deposition chamber for 4 to 6 seconds, and then nitrogen is introduced for 10 to 14 seconds, and this cycle is repeated 3 to 7 times;

[0014] First, 16 sccm to 20 sccm of TMA is introduced into the ALD deposition chamber for 7 s to 9 s; then nitrogen is introduced for 10 s to 14 s; then 20 sccm to 24 sccm of water vapor is introduced for 4 s to 6 s; finally, nitrogen is introduced for 10 s to 14 s, and this cycle is repeated 8 to 12 times to deposit an aluminum silicon layer.

[0015] In a possible embodiment, before placing the substrate into the ALD deposition chamber, the preparation method includes:

[0016] The first surface of the substrate includes a first area and a second area, the first area is used to set the gate line, and the separation layer is coated on the first area and cured.

[0017] In a possible embodiment, after placing the substrate with the aluminum silicon layer and the aluminum oxide layer into a PECVD deposition chamber, the preparation method includes:

[0018] The temperature in the PECVD deposition chamber is raised to 460° C. to 550° C. for 15 min to 25 min.

[0019] In a possible embodiment, when ammonia gas is introduced into the PECVD deposition chamber, a radio frequency power supply is turned on, and hydrogen ions in the ammonia gas are ionized, the preparation method includes:

[0020] 8000 sccm to 1100 sccm of ammonia and 3000 sccm to 6000 sccm of nitrous oxide are introduced into the PECVD deposition chamber, and the radio frequency power is 15000 KW to 18000 KW.

[0021] In a possible embodiment, when diffusing the hydrogen ions into the aluminum silicon layer, the preparation method includes:

[0022] Raising the temperature in the PECVD deposition chamber to 500° C. to 600° C.;

[0023] A silicon oxynitride layer and a silicon oxide layer are deposited.

[0024] In a possible embodiment, when ammonia gas is introduced into the PECVD deposition chamber, a radio frequency power supply is turned on, and hydrogen ions in the ammonia gas are ionized, the preparation method includes:

[0025] The PECVD deposition chamber is cooled to 300° C. to 400° C., and ammonia gas is introduced with a flow rate of 8000 sccm to 15000 sccm and a radio frequency power of 10000 KW to 18000 KW to generate free hydrogen ions.

[0026] In a possible embodiment, when diffusing the hydrogen ions into the aluminum silicon layer, the preparation method includes:

[0027] The infrared lamp in the PECVD deposition chamber is turned on and irradiated for 5 to 10 minutes.

[0028] In a second aspect, an embodiment of the present application further provides a photovoltaic cell, the photovoltaic cell comprising:

[0029] A substrate, the substrate comprising a first surface and a second surface relative to each other, the first surface being provided with a boron-doped layer, and the surface of the boron-doped layer being provided with an aluminum silicon layer, an aluminum oxide layer and a silicon nitride layer in sequence through any of the above-mentioned photovoltaic cell preparation methods.

[0030] In a possible embodiment, the thickness of the aluminum silicon layer is 0.5 nm to 1 nm.

[0031] The present application relates to a method for preparing a photovoltaic cell and a photovoltaic cell, the preparation method comprising: preparing a substrate, the substrate comprising a first surface and a second surface opposite to each other, the first surface being a velvet structure; placing the substrate into an ALD deposition chamber; depositing an aluminum silicon layer and an aluminum oxide layer on the first surface in sequence; placing the substrate with the aluminum silicon layer and the aluminum oxide layer into a PECVD deposition chamber; depositing a silicon nitride layer on the aluminum oxide layer; introducing ammonia gas into the PECVD deposition chamber, turning on a radio frequency power supply, ionizing hydrogen ions in the ammonia gas; and diffusing the hydrogen ions to the aluminum silicon layer. The aluminum silicon layer forms an aluminum-silicon bond on the first surface of the substrate, diffusing hydrogen ions to the aluminum silicon layer to form an aluminum-hydrogen bond. When ultraviolet light irradiates the surface of the photovoltaic cell, the aluminum-hydrogen bond can reduce the possibility of ultraviolet light damaging the silicon-hydrogen bond on the surface of the silicon layer, reducing the chemical passivation loss of the photovoltaic cell, thereby improving the conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0033] Figure 1 A schematic diagram of the structure of a substrate provided in an embodiment of the present application;

[0034] Figure 2 A schematic diagram of the structure of depositing an aluminum silicon layer on a substrate provided in an embodiment of the present application;

[0035] Figure 3 A schematic diagram of the structure of depositing an aluminum silicon layer and an aluminum oxide layer on a substrate provided in an embodiment of the present application;

[0036] Figure 4 A schematic diagram of a structure in which an isolation layer is coated on a substrate according to an embodiment of the present application;

[0037] Figure 5 For Figure 4 Schematic diagram of the structure of depositing aluminum silicon layer and aluminum oxide layer on the basis of

[0038] Figure 6 A schematic diagram of the structure of depositing an aluminum silicon layer, an aluminum oxide layer, a silicon nitride, a silicon oxynitride and a silicon oxide layer on a substrate provided in an embodiment of the application;

[0039] Figure 7 A schematic diagram of the structure of a photovoltaic cell provided in an embodiment of the present application;

[0040] Figure 8 A schematic structural diagram of another embodiment of a photovoltaic cell provided in an embodiment of the present application.

[0041] Reference numerals:

[0042] 1-Substrate;

[0043] 11- Silicon wafer;

[0044] 12-boron doped layer;

[0045] 13-BSG layer;

[0046] 14- tunneling oxide layer;

[0047] 15-poly layer;

[0048] 16-phosphorus-doped layer;

[0049] 17-PSG layer;

[0050] 2-aluminum silicon layer;

[0051] 3-aluminum oxide layer;

[0052] 4-Separation layer;

[0053] 5-silicon nitride layer;

[0054] 6-silicon oxynitride layer;

[0055] 7-silicon oxide layer;

[0056] 8- passivation layer;

[0057] 9-Grid lines. DETAILED DESCRIPTION

[0058] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0059] It should be clear that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0060] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0061] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0062] Photovoltaic cells convert absorbed sunlight into electrical energy through the photoelectric effect. In the process of photovoltaic cells absorbing sunlight, ultraviolet rays will irradiate the surface of the photovoltaic cells. The first surface of the substrate 1 has silicon-hydrogen bonds. The ultraviolet rays in the sunlight will destroy the silicon-hydrogen bonds after irradiating the substrate 1, resulting in excessive hydrogen atom groups on the first surface, which promotes carrier recombination and further affects the power generation efficiency of the photovoltaic cells.

[0063] like Figure 7 and Figure 8 As shown, an embodiment of the present application provides a photovoltaic cell, which includes a substrate 1, and the substrate 1 includes a first surface and a second surface relative to each other, wherein the first surface is provided with a boron-doped layer 12, and the surface of the boron-doped layer 12 is provided with an aluminum silicon layer 2, an aluminum oxide layer 3 and a silicon nitride layer 5 in sequence.

[0064] The aluminum silicon layer 2 can form an aluminum-silicon bond on the first surface of the substrate 1. During the preparation of the photovoltaic cell, hydrogen ions will diffuse into the aluminum silicon layer 2 to form an aluminum-hydrogen bond. The aluminum-hydrogen bond is located on the upper layer of the silicon-hydrogen bond. When ultraviolet light irradiates the surface of the photovoltaic cell, the aluminum-hydrogen bond reduces the possibility of ultraviolet light damaging the silicon-hydrogen bond, reduces the chemical passivation loss of the photovoltaic cell, and thus improves the conversion efficiency of the photovoltaic cell. The aluminum oxide layer 3 and the silicon nitride layer 5 improve the passivation effect of the photovoltaic cell. Compared with existing photovoltaic cells, the conversion efficiency of the photovoltaic cell provided in the embodiment of the present application is improved by 0.03% to 0.05%, and the reliability is improved by about 50%.

[0065] The present application sets an aluminum silicon layer 2 on the surface of the silicon wafer 11, and forms an aluminum-hydrogen bond after hydrogen injection to reduce the chemical passivation loss caused by ultraviolet rays to the photovoltaic module. The present solution does not limit the type of photovoltaic cells, and the type of photovoltaic cells can be a Passivated Emitter Rear Cell (PERC), an oxide passivated contact cell (TOPCon), etc.

[0066] For PERC cells, along the thickness direction, PERC cells include front surface metal silver electrode, front surface silicon nitride passivation layer, phosphorus layer emitter, P-type base silicon layer, local aluminum back field, metal aluminum back electrode, back passivation layer (Al2O3 / SiNx). PERC cells use a passivation film to passivate the back, replacing the full aluminum back field, enhancing the internal back reflection of light in the silicon base, reducing the recombination rate on the back, and increasing the efficiency of the cell by 0.5%-1%.

[0067] For TOPCon cells, along the thickness direction, TOPCon cells include metal silver electrodes, front surface silicon nitride passivation layers, boron-doped emitters, N-type base silicon layers, diffused doping layers, ultra-thin silicon oxide, doped polysilicon, silicon nitride, and metal silver electrodes. The back of the cell is composed of a layer of ultra-thin silicon oxide (1nm to 2nm) and a layer of phosphorus-doped microcrystalline amorphous mixed Si film, which together form a passivation contact structure. This structure can block the recombination of minority carrier holes and increase the open circuit voltage and short circuit current of the cell. The ultra-thin oxide layer allows majority electrons to tunnel into the polysilicon layer while blocking the recombination of minority carrier holes. The good passivation effect of ultra-thin silicon oxide and heavily doped silicon film causes the energy band on the silicon wafer surface to bend, thereby forming a field passivation effect, greatly increasing the probability of electron tunneling, reducing contact resistance, and increasing the open circuit voltage and short circuit current of the cell, thereby improving the cell conversion efficiency.

[0068] The above two types of photovoltaic cells can be multi-busbar cells (MBB) or busbar-free cells (0BB).

[0069] For multi-busbar cells, multiple busbars for collecting current are set on the surface of the cell, which shortens the current conduction path in the multi-busbar cell, reduces internal losses, and thus improves the power of the multi-busbar cell. As the number of busbars increases, the cross-sectional area of ​​the busbars and the Han Dynasty decreases, and the film layer becomes thinner, which can reduce the production cost of photovoltaic modules. As the number of busbars increases, the number of fine grids can be reduced accordingly, which can reduce the production cost of the cell.

[0070] For busbar-free cells, there is no busbar on the surface of the cell. After welding multiple cells, the welding strip replaces the original busbar and directly connects to the fine grid, which can reduce the consumption of silver paste and the production cost of the cell. Busbar-free cells can reduce the shading area of ​​the grid line 9 in the cell, reduce the transmission loss of the fine grid, and improve the total power of the component. At the same time, the increase in the fine grid contact points reduces the risk of hidden cracks in the thin silicon wafer 11, and improves the yield and reliability.

[0071] like Figure 7 and Figure 8 As shown, in a possible embodiment, the second surface of the substrate 1 includes a tunneling oxide layer 14 , a poly layer 15 and a phosphorus-doped layer 16 arranged in sequence, and a passivation layer 8 may also be arranged on the phosphorus-doped layer 16 .

[0072] The combination of the tunneling oxide layer 14 and the phosphorus-doped layer 16 allows the majority electrons to tunnel into the poly layer 15, while blocking the recombination of minority holes. Then, the electrons are transversely transmitted in the poly layer 15 and collected by the metal, which greatly reduces the recombination rate and improves the open circuit voltage and short circuit current of the battery, thereby improving the battery conversion efficiency. The silicon nitride layer 5 and the poly layer 15 together form a passivation contact structure, which utilizes the quantum tunneling effect to allow majority electrons to tunnel and block minority holes from penetrating, thereby reducing recombination. The silicon nitride layer 5 can also reduce the recombination rate of surface electrons and holes, further reducing the efficiency loss caused by surface recombination, thereby improving the overall efficiency of the photovoltaic cell.

[0073] In a possible embodiment, the thickness of the aluminum silicon layer 2 is 0.5 nm to 1 nm.

[0074] The aluminum silicon layer 2 is used to form an aluminum silicon layer 2 on the first surface of the substrate 1, and then combine with hydrogen ions to form aluminum-hydrogen bonds to reduce the chemical loss caused by ultraviolet rays to the photovoltaic cell. If the thickness of the aluminum silicon layer 2 is less than 0.5nm, the compactness of the aluminum silicon layer 2 on the first surface of the substrate 1 is poor, and the silicon surface of the first surface cannot be completely covered, resulting in poor overall resistance to ultraviolet damage of the photovoltaic cell. If the thickness of the aluminum silicon layer 2 is greater than 1nm, the contact between the metal electrode and the boron doped layer 12 will be reduced, and it may also cause sunlight to be difficult to reach the boron doped layer 12, thereby affecting the power generation efficiency of the photovoltaic cell. Therefore, the thickness of the aluminum silicon layer 2 can be 0.5nm, 0.7nm, 1nm, etc., which increases the coverage rate of the silicon surface of the first surface of the substrate 1 by the aluminum silicon layer 2 and improves the resistance of the photovoltaic cell to ultraviolet damage.

[0075] Compared with the conventional structure in which only an aluminum oxide layer 3 is arranged on the silicon layer on the first surface of the substrate 1, when the ultraviolet intensity is UV15, the attenuation rate of the photovoltaic cell is 0.87%, when the ultraviolet intensity is UV30, the attenuation rate of the photovoltaic cell is 0.70%, and when the ultraviolet intensity is UV60, the attenuation rate of the photovoltaic cell is 2.33%; in the embodiment of the present application, an aluminum silicon layer 2 is arranged between the aluminum oxide layer 3 and the silicon layer, and aluminum-hydrogen bonds are formed after hydrogen injection. When the ultraviolet intensity is UV15, the attenuation rate of the photovoltaic cell is 0.48%, when the ultraviolet intensity is UV30, the attenuation rate of the photovoltaic cell is 0.67%, and when the ultraviolet intensity is UV60, the attenuation rate of the photovoltaic cell is 1.22%. Therefore, the photovoltaic cell provided in the embodiment of the present application has a lower attenuation rate under ultraviolet irradiation.

[0076] Compared with the solution without the aluminum silicon layer 2, the front attenuation rate of the photovoltaic cell under the ultraviolet light with an intensity of UV30 is 1.81%, and the front attenuation rate of the photovoltaic cell under the ultraviolet light with an intensity of UV60 is 2.27%; the photovoltaic cell provided in the embodiment of the present application has a front attenuation rate of 1.22% under the ultraviolet light with an intensity of UV30, and a front attenuation rate of 1.25% under the ultraviolet light with an intensity of UV60. Therefore, the photovoltaic cell provided in the embodiment of the application has a lower front attenuation rate under the irradiation of ultraviolet light of different intensities. Through EL image detection of the photovoltaic cell after attenuation due to ultraviolet irradiation, the overall brightness of the EL image of the photovoltaic cell provided in the embodiment of the present application is higher and the degree of damage is lower.

[0077] Compared with photovoltaic cells without the aluminum silicon layer 2, the photovoltaic cells provided in the embodiment of the present application have better electrical performance, with the open circuit voltage increased by 0.2mV to 0.3mV, the fill factor increased by 0.04% to 0.11%, and the conversion efficiency increased by about 0.02%.

[0078] like Figures 1 to 6 As shown, the present application embodiment provides a method for preparing a photovoltaic cell, comprising:

[0079] S1, preparing a substrate 1, wherein the substrate 1 comprises a first surface and a second surface opposite to each other, wherein the first surface has a suede structure;

[0080] S2, placing the substrate 1 into the ALD deposition chamber;

[0081] S3, depositing an aluminum silicon layer 2 and an aluminum oxide layer 3 in sequence on the first surface;

[0082] S4, placing the substrate 1 with the aluminum silicon layer 2 and the aluminum oxide layer 3 into a PECVD deposition chamber;

[0083] S5, depositing a silicon nitride layer 5 on the aluminum oxide layer 3;

[0084] S6, introducing ammonia gas into the PECVD deposition chamber, turning on the radio frequency power supply, and ionizing hydrogen ions in the ammonia gas;

[0085] S7, diffusing hydrogen ions into the aluminum silicon layer 2.

[0086] An aluminum silicon layer 2 is deposited on the upper surface of the substrate 1, which can form an aluminum silicon bond on the first surface, reduce the interface defect density of the first surface, diffuse the ionized hydrogen ions to the aluminum silicon layer 2, and combine the free hydrogen ions with the defects of the aluminum silicon layer 2 and the aluminum oxide interface. Due to the ionic nature, the aluminum silicon bond will form positive and negative charge centers through electron transfer, and will generate free electron-hole pairs under the stimulation of the external environment to form aluminum hydrogen bonds, replacing the silicon hydrogen bonds in the prior art, thereby reducing chemical passivation losses and improving the efficiency of photovoltaic cells.

[0087] like Figure 1 As shown, in a possible embodiment, the first surface of the substrate 1 is a velvet surface, and the second surface is sequentially provided with a tunneling oxide layer 14, a poly layer 15 and a phosphorus-doped layer 16. The steps of preparing the substrate 1 are:

[0088] S11, preparing a silicon wafer 11, and performing double-sided texturing on the silicon wafer 11;

[0089] S12, performing boron diffusion on the silicon wafer 11 after texturing to form a boron doped layer 12, and forming a PN junction on the surface of the silicon wafer 11;

[0090] S13, chain-removing the BSG layer 13 on the second surface of the silicon wafer 11, then performing alkali polishing to polish the second surface of the silicon wafer 11, and finally chain-removing the BSG layer 13 on the first surface of the silicon wafer 11;

[0091] S14, depositing a tunnel oxide layer 14 and a poly layer 15 in sequence on the second surface of the silicon wafer 11 by using a LPCVD double insertion method;

[0092] S15, performing phosphorus doping annealing on the second surface of the silicon wafer 11 by double insertion to form a phosphorus doped layer 16;

[0093] S16, chain-type removal of PSG on the second surface of the silicon wafer 11 and the plating on the first surface.

[0094] Double-sided texturing of the silicon wafer 11 can improve the light absorption efficiency of the silicon wafer 11. Boron diffusion is performed on the surface of the silicon wafer 11 to form a PN junction. When sunlight is irradiated on the PN junction, internal electrons can be excited to generate current. After boron diffusion, a BSG layer 13 will be formed on the surface of the silicon wafer 11. After removing the BSG layer 13, the second surface of the silicon wafer 11 is polished to improve the passivation effect of the second surface of the silicon wafer 11 and the carrier transmission performance. Depositing a tunneling oxide layer 14 on the second surface can reduce the minority carrier recombination rate, increase the open circuit voltage and short circuit current of the battery, and thus improve the conversion efficiency of the battery. The poly layer 15 can passivate the surface and select charge carriers on the second surface, further optimizing the performance of the battery. A phosphorus-doped layer 16 is provided on the second surface to improve the photoelectric conversion efficiency, optimize the electrical properties of the substrate 1, and reduce surface recombination and metal contact recombination. A PSG layer 17 will be formed during the phosphorus diffusion process. Removing the PSG layer 17 and the first surface plating facilitates subsequent processing of the substrate 1.

[0095] In a possible embodiment, when the substrate 1 is placed in the ALD deposition chamber, the preparation method includes:

[0096] S21, placing the second surfaces of the plurality of substrates 1 relatively to the first carrier, and then placing the second surfaces of the plurality of substrates 1 into the ALD deposition chamber along with the first carrier.

[0097] The second surface of the substrate 1 in the first carrier is placed opposite to the first surface of the substrate 1 so that the first surface of the substrate 1 is exposed, so that the aluminum silicon layer 2 and the aluminum oxide layer 3 can be deposited on the first surface of the substrate 1 in the ALD deposition chamber.

[0098] like Figure 2 As shown, in a possible embodiment, when the aluminum silicon layer 2 is deposited on the first surface, the preparation method includes:

[0099] S31. First, water vapor is introduced into the ALD deposition chamber at a flow rate of 18 sccm to 22 sccm for a duration of 4 s to 6 s. Then, nitrogen is introduced for a purge of 10 s to 14 s. This cycle is repeated 3 to 7 times.

[0100] S32. TMA is introduced into the ALD deposition chamber at a flow rate of 16 sccm to 20 sccm for a duration of 7s to 9s; then nitrogen is introduced for 10s to 14s; then water vapor is introduced at a flow rate of 20 sccm to 24 sccm for a duration of 4s to 6s; finally, nitrogen is introduced for 10s to 14s, and this cycle is repeated 8 to 12 times to deposit the aluminum silicon layer 2.

[0101] The first surface of the substrate 1 is a velvet structure. During the preparation of the substrate 1, impurities are likely to remain in the recessed positions. In S31, the surface of the substrate 1 can be cleaned by alternatingly blowing water vapor and nitrogen, so that the impurities generated during the preparation of the substrate 1 are separated from the surface of the substrate 1 along with the water vapor and / or nitrogen.

[0102] Then, an aluminum silicon layer 2 is deposited on the first surface of the substrate 1 through S32, and TMA (trimethylaluminum) is introduced to deposit aluminum bonds on the first surface to form aluminum silicon bonds with the silicon on the first surface. The flow rate of TMA is relatively low, which can be 16sccm, 18sccm, 20sccm, etc., and the duration is relatively long, which can be 7s, 8s, 9s, etc., so that more TMA is attached to the first surface, and then it is convenient to form aluminum silicon bonds with the silicon on the surface of the substrate 1 to form an aluminum silicon layer 2. After TMA deposition, nitrogen gas is introduced for purging to make the TMA on the first surface adhere more evenly, and the TMA not attached to the first surface will be blown out of the ALD deposition chamber by nitrogen gas to remove excess TMA. Water vapor will make the TMA on the surface form a thinner aluminum oxide, which is used to connect two TMA depositions. The water vapor flow rate can be as high as 20sccm, 22sccm, 24sccm, etc., and the duration can be as short as 4s, 5s, 6s, etc., to improve the preparation efficiency of photovoltaic cells. At the same time, it can also reduce the possibility of TMA being completely oxidized into aluminum oxide, increase the content of aluminum bonds in the aluminum silicon layer 2, and enable the aluminum bonds to form aluminum silicon bonds with the silicon surface of the substrate. After the water vapor is introduced, nitrogen is introduced for purging to blow the remaining water vapor out of the ALD deposition chamber. Since the first surface of the substrate 1 is a velvet structure, it is not convenient for TMA to attach. The above process can be repeated 8 times, 10 times, 12 times, etc., so that a dense aluminum silicon layer 2 of 0.5nm to 1nm can be formed on the velvet structure of the first surface, reducing the possibility of silicon layer exposure.

[0103] like Figure 3 As shown, in a possible embodiment, when the aluminum oxide layer 3 is deposited on the first surface, the preparation method includes:

[0104] S33. Introduce TMA into the ALD deposition chamber with a flow rate of 18 sccm to 22 sccm and a duration of 6 s to 8 s; then introduce nitrogen gas for 10 s to 14 s; then introduce water vapor with a flow rate of 18 sccm to 22 sccm and a duration of 6 s to 8 s, and finally introduce nitrogen gas for 10 s to 14 s, and repeat this cycle 18 to 22 times.

[0105] When depositing the aluminum oxide layer 3, the flow rate of TMA can be 18sccm, 20sccm, 22sccm, etc., and the duration can be 6s, 7s, 8s, etc., so that TMA is deposited on the first surface; then nitrogen purge can be used to improve the uniformity of TMA on the first surface, and at the same time, excess TMA can be blown out; then water vapor is introduced to oxidize TMA into the aluminum oxide layer 3, and the flow rate of water vapor can be 18sccm, 20sccm, 22sccm, etc., and the duration can be 6s, 7s, 8s, etc., so that TMA can be fully oxidized to form the aluminum oxide layer 3; finally, nitrogen purge is used to blow out excess water vapor. The above process can be repeated 18 times, 20 times, 22 times, etc., and an aluminum oxide layer 3 with a thickness of 2nm to 4nm is deposited on the aluminum silicon layer 2 on the first surface to improve the passivation effect of the first surface.

[0106] like Figure 4 and Figure 5 As shown, in a possible embodiment, before placing the substrate 1 into the ALD deposition chamber, the preparation method includes:

[0107] S20, the first surface of the substrate 1 includes a first area and a second area, the first area is used to set the gate line 9, and the separation layer 4 is coated on the first area and cured.

[0108] The separation layer 4 can be a coating with high temperature resistance and hydrophobicity such as polytetrafluoroethylene. When the substrate 1 is placed in the ALD deposition chamber to deposit the aluminum silicon layer 2 and / or the aluminum oxide layer 3, the first area coated with the separation layer 4 is less likely to adhere to TMA, thereby reducing the possibility of forming the aluminum silicon layer 2 and the aluminum oxide layer 3 in the first area. When the gate line 9 is subsequently set, there is no need to corrode the aluminum silicon layer 2 and / or the aluminum oxide layer 3 in the first area, so that the gate line 9 is easier to contact with the boron doped layer 12, reducing the recombination loss at the position of the gate line 9.

[0109] In a possible embodiment, before placing the substrate 1 with the aluminum silicon layer 2 and the aluminum oxide layer 3 into the PECVD deposition chamber, the preparation method includes:

[0110] S41, placing the second surfaces of the plurality of substrates 1 on a second carrier relative to each other, and then placing the second carrier into a PECVD deposition chamber.

[0111] The second surface of the substrate 1 is placed oppositely so that the first surface of the substrate 1 is exposed in the PECVD deposition chamber, and the silicon nitride layer 5 can be deposited on the first surface.

[0112] In a possible embodiment, after placing the substrate 1 with the aluminum silicon layer 2 and the aluminum oxide layer 3 into a PECVD deposition chamber, the preparation method includes:

[0113] S42, raising the temperature in the PECVD deposition chamber to 460°C to 550°C for 15 minutes to 25 minutes.

[0114] The temperature in the PECVD deposition chamber can be increased to 460° C., 500° C., 550° C., etc., which can provide deposition conditions for the silicon nitride layer 5. The decomposition temperature of polytetrafluoroethylene is 350° C. The temperature in the PECVD deposition chamber is higher than the decomposition temperature of polytetrafluoroethylene, so that polytetrafluoroethylene can be decomposed and discharged with the tail gas.

[0115] In a possible embodiment, when ammonia gas is introduced into the PECVD deposition chamber, a radio frequency power supply is turned on, and hydrogen ions in the ammonia gas are ionized, the preparation method includes:

[0116] S61. Introduce 8000 sccm to 1100 sccm of ammonia and 3000 sccm to 6000 sccm of nitrous oxide into the PECVD deposition chamber, and turn on the RF power supply at a power of 15000 KW to 18000 KW.

[0117] When the RF power is 15000KW to 18000KW, the ammonia gas introduced into the PECVD deposition chamber will ionize hydrogen ions, and the nitrous oxide will ionize oxygen atoms. The free hydrogen ions can combine with the oxygen atoms in the nitrous oxide to form hydroxyl groups, and the hydroxyl groups can combine with the aluminum ions to improve the passivation effect of the aluminum oxide layer 3. The flow rate of ammonia gas can be 8000sccm, 1000sccm, 1100sccm, etc., and the flow rate of nitrous oxide can be 3000sccm, 4500sccm, 6000sccm, etc., so that more hydrogen ions are ionized from ammonia gas, part of which is combined with oxygen in the nitrous oxide, and the other part can diffuse into the aluminum silicon layer 2 and the aluminum oxide layer 3.

[0118] like Figure 6 As shown, when diffusing the hydrogen ions into the aluminum silicon layer 2, the preparation method includes:

[0119] S71, raising the temperature in the PECVD deposition chamber to 500° C. to 600° C.;

[0120] S72 , depositing a silicon oxynitride layer 6 and a silicon oxide layer 7 .

[0121] Increasing the temperature in the PECVD deposition chamber to 500°C to 600°C and maintaining it for 2 to 5 minutes can increase the activity of hydrogen ions, allowing them to pass through the silicon nitride film layer and diffuse to the aluminum silicon layer 2 and the aluminum oxide interface. Since the aluminum silicon layer 2 is ionic, the aluminum silicon bond will form positive and negative charge centers through electron transfer, and free electron-hole pairs will be generated during the heating process to form aluminum-hydrogen bonds, replacing the silicon-hydrogen bonds at the conventional interface, thereby reducing chemical passivation losses. Other ions ionized by ammonia and nitrous oxide will be discharged with the tail gas.

[0122] In an environment of 500°C to 600°C, silane, ammonia and nitrous oxide are introduced into the PECVD deposition chamber to facilitate the deposition of a silicon nitride oxide layer 6 on the first surface, which can reduce the surface state density and inhibit carrier recombination, thereby increasing the open circuit voltage, and can also reduce the reflection of sunlight by the photovoltaic cell, increase the absorption of sunlight, and thus increase the short-circuit current; silane and nitrous oxide are then introduced into the PECVD deposition chamber to facilitate the deposition of a silicon oxide layer 7 on the first surface, thereby improving the passivation effect of the first surface.

[0123] In a possible embodiment, when ammonia gas is introduced into the PECVD deposition chamber, a radio frequency power supply is turned on, and hydrogen ions in the ammonia gas are ionized, the preparation method includes:

[0124] S62. Lower the temperature in the PECVD deposition chamber to 300°C to 400°C, then introduce ammonia gas with a flow rate of 8000sccm to 15000sccm and a radio frequency power of 10000KW to 18000KW to generate free hydrogen ions.

[0125] The RF power can be 10000KW, 15000KW, or 18000KW, so that ammonia absorbs energy in the high-RF electromagnetic field and decomposes into hydrogen ions and nitrogen atoms, wherein the free hydrogen ions are used to diffuse to the aluminum silicon layer 2, and the nitrogen atoms can be discharged from the PECVD deposition chamber with the tail gas. When depositing the silicon nitride layer 5, the temperature in the PECVD deposition chamber is 450°C to 520°C. The temperature in the PECVD deposition chamber is reduced to 300°C to 400°C to reduce the activity of the hydrogen ions ionized from the ammonia. If the temperature in the PECVD deposition chamber is higher than 400°C, the hydrogen ions are too active and the effect of combining with the surface of the aluminum silicon layer 2 is poor, resulting in poor UV resistance of the photovoltaic cell.

[0126] When diffusing hydrogen ions into the aluminum silicon layer 2, the preparation method includes:

[0127] S73, turn on the infrared lamp in the PECVD deposition chamber and irradiate for 5 to 10 minutes.

[0128] Infrared rays increase the activity of hydrogen ions and inject hydrogen ions into the aluminum silicon layer 2. Under the stimulation of infrared rays, the aluminum silicon bond will form positive and negative charge centers through electron transfer, generate free electron-hole pairs, and combine with hydrogen ions to form aluminum-hydrogen bonds, which reduce the chemical passivation loss of photovoltaic cells under ultraviolet irradiation.

[0129] like Figure 7 and Figure 8 As shown, after diffusing hydrogen ions into the aluminum silicon layer 2, the preparation method includes:

[0130] S8, depositing a passivation layer 8 on the second surface of the substrate 1 by PECVD;

[0131] S9, printing the gate lines 9 on the first surface and the second surface of the substrate 1 by screen printing.

[0132] The passivation layer 8 is deposited on the phosphorus-doped layer 16 on the second surface of the substrate 1 to improve the passivation effect of the second surface and thus improve the conversion efficiency of the photovoltaic cell.

[0133] The present application relates to a method for preparing a photovoltaic cell and a photovoltaic cell, the preparation method comprising: preparing a substrate 1, the substrate 1 comprising a first surface and a second surface opposite to each other, the first surface being a velvet structure; placing the substrate 1 in an ALD deposition chamber; depositing an aluminum silicon layer 2 and an aluminum oxide layer 3 on the first surface in sequence; placing the substrate 1 with the aluminum silicon layer 2 and the aluminum oxide layer 3 in a PECVD deposition chamber; depositing a silicon nitride layer 5 on the aluminum oxide layer 3; introducing ammonia gas into the PECVD deposition chamber, turning on a radio frequency power supply, ionizing hydrogen ions in the ammonia gas; and diffusing the hydrogen ions to the aluminum silicon layer 2. The aluminum silicon layer 2 can form an aluminum-silicon bond on the first surface of the substrate 1, and diffusing hydrogen ions to the aluminum silicon layer 2 will form an aluminum-hydrogen bond at the aluminum-silicon bond. When ultraviolet light irradiates the surface of the photovoltaic cell, the aluminum-hydrogen bond can reduce the possibility of ultraviolet light damaging the silicon-hydrogen bond on the surface of the silicon layer, reducing the chemical passivation loss of the photovoltaic cell, thereby improving the conversion efficiency.

Claims

1. A method for preparing a photovoltaic cell, characterized in that: The preparation method comprises: Prepare a substrate, the substrate comprising a first surface and a second surface opposite to each other, the first surface having a suede structure; placing the substrate into an ALD deposition chamber; Depositing an aluminum silicon layer and an aluminum oxide layer on the first surface in sequence; placing the substrate with the aluminum silicon layer and the aluminum oxide layer into a PECVD deposition chamber; depositing a silicon nitride layer on the aluminum oxide layer; Introducing ammonia gas into the PECVD deposition chamber, turning on the radio frequency power supply, and ionizing hydrogen ions in the ammonia gas; The hydrogen ions are diffused into the aluminum silicon layer.

2. The method for preparing a photovoltaic cell according to claim 1, characterized in that: When an aluminum silicon layer and an aluminum oxide layer are sequentially deposited on the first surface, the preparation method comprises: First, 18 sccm to 22 sccm of water vapor is introduced into the ALD deposition chamber for 4 to 6 seconds, and then nitrogen is introduced for 10 to 14 seconds, and this cycle is repeated 3 to 7 times; First, 16 sccm to 20 sccm of TMA is introduced into the ALD deposition chamber for 7 s to 9 s; then nitrogen is introduced for 10 s to 14 s; then 20 sccm to 24 sccm of water vapor is introduced for 4 s to 6 s; finally, nitrogen is introduced for 10 s to 14 s, and this cycle is repeated 8 to 12 times to deposit an aluminum silicon layer.

3. The method for preparing a photovoltaic cell according to claim 1, characterized in that: Before placing the substrate into the ALD deposition chamber, the preparation method includes: The first surface of the substrate includes a first area and a second area, the first area is used to set the gate line, and the separation layer is coated on the first area and cured.

4. The method for preparing a photovoltaic cell according to claim 1, characterized in that: After placing the substrate with the aluminum silicon layer and the aluminum oxide layer into a PECVD deposition chamber, the preparation method comprises: The temperature in the PECVD deposition chamber is raised to 460° C. to 550° C. for 15 min to 25 min.

5. The method for preparing a photovoltaic cell according to claim 4, characterized in that: When ammonia gas is introduced into the PECVD deposition chamber, a radio frequency power supply is turned on to ionize hydrogen ions in the ammonia gas, the preparation method comprises: 8000 sccm to 1100 sccm of ammonia and 3000 sccm to 6000 sccm of nitrous oxide are introduced into the PECVD deposition chamber, and the radio frequency power is 15000 KW to 18000 KW.

6. The method for preparing a photovoltaic cell according to claim 1, characterized in that: When diffusing the hydrogen ions into the aluminum silicon layer, the preparation method comprises: Raising the temperature in the PECVD deposition chamber to 500° C. to 600° C.; A silicon oxynitride layer and a silicon oxide layer are deposited.

7. The method for preparing a photovoltaic cell according to claim 6, characterized in that: When ammonia gas is introduced into the PECVD deposition chamber, a radio frequency power supply is turned on to ionize hydrogen ions in the ammonia gas, the preparation method comprises: The PECVD deposition chamber is cooled to 300° C. to 400° C., and ammonia gas is introduced with a flow rate of 8000 sccm to 15000 sccm and a radio frequency power of 10000 KW to 18000 KW to generate free hydrogen ions.

8. The method for preparing a photovoltaic cell according to claim 7, characterized in that: When diffusing the hydrogen ions into the aluminum silicon layer, the preparation method comprises: The infrared lamp in the PECVD deposition chamber is turned on and irradiated for 5 to 10 minutes.

9. A photovoltaic cell, characterized in that: The photovoltaic cell comprises: A substrate, the substrate comprising a first surface and a second surface relative to each other, the first surface being provided with a boron-doped layer, and the surface of the boron-doped layer being provided with an aluminum silicon layer, an aluminum oxide layer and a silicon nitride layer in sequence through the preparation method of a photovoltaic cell according to any one of claims 1 to 8.

10. The photovoltaic cell according to claim 9, characterized in that: The thickness of the aluminum silicon layer is 0.5 nm to 1 nm.

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