Preparation method of N-TOPCON battery and battery structure

Abstract

The invention discloses a preparation method of an N-TOPCON cell and a cell structure, and belongs to the technical field of solar cell production, and the preparation method comprises the steps of texturing, boron diffusion doping, alkali polishing, SiO layer and N + polycrystalline silicon layer forming, RCA cleaning, aluminum oxide film ALD, silicon nitride film deposition, screen printing, sintering and light injection. The ALD aluminum oxide film is formed by depositing an aluminum oxide film on the surface of the N-type silicon substrate by adopting an atomic layer deposition process, and trimethylaluminum and water are used as reactants; ultraviolet lamp curing treatment is added before silk-screen printing, and curing treatment is carried out on the front face of the N-type silicon substrate through an ultraviolet lamp at the normal temperature. An ultraviolet curing lamp is adopted for irradiation and directly acts on Si-H bonds and defect states in the passivation layer, densification of silicon nitride of the SiNx layer is promoted, the refractive index of the silicon nitride is improved, the light trapping capacity is enhanced, generation of dangling bonds on an interface of the passivation layer is reduced, the recombination rate rise caused by breakage of the Si-H bonds is restrained, and therefore the efficiency attenuation rate is decreased.

Description

Technical Field

[0001] The present invention belongs to the technical field of solar cell production, and specifically relates to a preparation method and a battery structure of an N-TOPCON battery. Background Art

[0002] In recent years, with the continuous expansion of the production capacity of TOPCon batteries, due to the relatively high conversion efficiency and bifaciality of the bifacial battery structure of TOPCon batteries compared to PERC batteries, which can effectively reduce the installation cost of power stations, TOPCon battery modules are increasingly favored by the market terminal. The process flow of TOPCon batteries is texturing - boron diffusion - alkaline polishing - N+ layer poly-silicon - RCA cleaning - ALD alumina - front nitriding film - back silicon nitride - screen printing - sintering - light injection - testing.

[0003] The Topcon battery structure commonly uses a stack of silicon nitride and alumina as the passivation layer. Hydrogen elements usually exist in the form of bonds such as Si-H, N-H, Si-O-H, Al-O-H, etc. at the interface or in the lattice, which plays a key role in the passivation effect and the stability of the topcon battery. Among them, the bond energy of Si-H is the lowest, and it is also the structure that is most obvious for removing dangling bonds and passivation efficiency at the silicon interface, and it is also very easy to be broken by ultraviolet rays. After ultraviolet rays penetrate the antireflection layer on the battery surface, they will break the chemical bond structure of the silicon nitride (SiNx) or alumina (AlOx) passivation layer, resulting in the degradation of the surface passivation effect.

[0004] The existing alumina process is produced by reacting water with TMA. A large amount of hydrogen ions are produced during the reaction process. These hydrogen ions accumulate in the silicon wafer interface layer and inside the alumina, playing a passivation role on the silicon wafer surface. When the silicon wafer is irradiated with ultraviolet light, the Si-H bond breaks, and the hydrogen ions escape, resulting in passivation failure, leading to a decrease in battery efficiency and a decrease in the power generation power of the module. When the existing TOPCon solar cells and modules are used, the hydrogen bonds or defect state density in the battery passivation layer increase under long-term ultraviolet (UV) irradiation, resulting in a significant attenuation of the open-circuit voltage (Voc) and fill factor (FF), and a significant decrease in battery efficiency and module power. Traditional solutions optimize the passivation layer materials (such as SiNx, AlOx) or add a barrier layer, but there are problems such as complex processes, high costs, and limited attenuation improvement. Summary of the Invention

[0005] To overcome the problem that in the prior art, there is still an increase in the hydrogen bonds or defect state density in the battery passivation layer of TOPCon batteries and modules under long-term ultraviolet (UV) irradiation, resulting in a significant attenuation of the open-circuit voltage (Voc) and fill factor (FF), and low battery efficiency and module power, the present invention provides a preparation method and a battery structure of an N-TOPCON battery, and the specific content is as follows:

[0006] A preparation method of an N-TOPCON battery, including texturing, boron diffusion doping, alkali polishing, forming an SiO layer and an N+ polysilicon layer, RCA cleaning, ALD alumina film, depositing a silicon nitride film, screen printing, sintering, and photo-injection;

[0007] The ALD alumina film is deposited on the surface of the N-type silicon substrate by atomic layer deposition technology, using trimethylaluminum and water as reactants, and the hydrogen ion concentration of the deposited alumina film is 10¹ 9 -10² 0 atoms / cm³;

[0008] Before the screen printing, ultraviolet lamp curing treatment is added. At room temperature, the front side of the N-type silicon substrate is cured with an ultraviolet lamp. The ultraviolet wavelength of the curing lamp is 200 - 280 nm, the light intensity is 50 - 200 W / cm², and the irradiation time is 1 - 200 s.

[0009] Further, the temperature of the photo-injection is 200 - 600 °C, the time is 100 - 300 s, and the energy density is 1 - 5 W / cm².

[0010] Further, the pulse time of water and trimethylaluminum in the atomic layer deposition process is 10 - 30 s, the purge time is 10 - 30 s, the flow rates are both 20 - 40 sccm, the number of cycles is 30 - 50 times, and the reaction temperature is 280 - 310 °C.

[0011] Further, the thickness of the alumina film is 3 - 10 nm.

[0012] Further, the refractive index of the silicon nitride film is 2.00 - 2.20, and the thickness is 70 - 90 nm.

[0013] Further, the curing treatment uses an ultraviolet LED array curing lamp.

[0014] Further, the texturing treatment in step S1 is to form a nano-level textured surface on the surface of the N-type silicon wafer.

[0015] This application also provides an N-TOPCON battery structure, which is characterized in that it is prepared by the preparation method of the N-TOPCON battery structure according to any one of claims 1 - 5, and includes an N-type silicon substrate. On the front side of the N-type silicon substrate, a P+ layer, an alumina film, and a front-side silicon nitride film are stacked in sequence from inside to outside. On the back side of the N-type silicon substrate, an SiO layer, an N+ polysilicon layer, and a back-side silicon nitride film are stacked in sequence from inside to outside; the hydrogen ion concentration in the alumina film is 10¹ 9 -10² 0 atoms / cm³.

[0016] Furthermore, the attenuation ratio threshold of the battery under UV60kWh irradiation is ≤1.0%, and the attenuation ratio threshold of the battery module is ≤1.5%.

[0017] The beneficial effects of adopting the technical solution of the present invention are as follows:

[0018] (1) By using an ultraviolet LED array and a curing lamp with adjustable irradiation intensity, directly acting on the Si-H bonds and defect states in the passivation layer, the silicon-hydrogen bond density of the alumina film is reduced to below the anti-UV attenuation threshold through ultraviolet light pretreatment. The UV curing lamp promotes the densification of silicon nitride in the SiNx layer through irradiation with a specific wavelength, improves its refractive index to enhance the light trapping ability, reduces the generation of dangling bonds at the passivation layer interface, thereby inhibiting the increase in the recombination rate caused by the breakage of Si-H bonds, and further improving the battery efficiency and module power.

[0019] (2) During the curing process of the UV lamp, the local temperature on the aluminum surface may exceed the ambient temperature, further promoting the rapid thickening of the alumina layer in a short time. The alumina enhances the interface passivation effect through a photochemical cross-linking reaction, increases the densification, reduces the surface recombination current density, and reduces the efficiency attenuation rate of the TOPCon battery under UV irradiation. The strengthening of the interface between the AlOx layer and the intrinsic silicon can reduce the silicon-hydrogen bond density at the interface and reduce the degree of damage to the silicon-hydrogen bond by UV. Description of the Drawings

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0021] Figure 1 It is a schematic structural diagram of an N-TOPCON battery structure of the present invention;

[0022] In the figure, 1 is an N-type silicon substrate; 2 is a P+ layer; 3 is an alumina film; 4 is a front silicon nitride film; 5 is an SiO layer; 6 is an N+ polysilicon layer; 7 is a back silicon nitride film. Detailed Embodiments

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0024] In this embodiment, an ultraviolet LED array and a curing lamp with adjustable irradiation intensity are used, which directly act on the Si-H bonds and defect states in the passivation layer. Short-wavelength UV-C is more likely to trigger the dissociation of silicon-hydrogen bonds due to its higher energy and is used for high-intensity irradiation during wafer photo-erasure, which can significantly damage the silicon-hydrogen bonds. After the passivation layer is damaged, the surface recombination rate of the battery increases, further exacerbating carrier loss. The specific implementation is as follows:

[0025] Refer to Figure 1 As shown, a preparation method of an N-TOPCON battery includes texturing, boron diffusion doping, alkali polishing, forming an SiO layer 5 and an N+ polysilicon layer 6, RCA cleaning, ALD alumina film 3, depositing a silicon nitride film, screen printing, sintering, and photo-injection;

[0026] The ALD alumina film 3 is deposited on the surface of the N-type silicon substrate 1 by atomic layer deposition technology, using trimethylaluminum and water as reactants. The hydrogen ion concentration of the deposited alumina film 3 is 10¹ 9 -10² 0 atoms / cm³;

[0027] Before the screen printing, an ultraviolet lamp curing treatment is added. At room temperature, the front side of the N-type silicon substrate 1 is cured using an ultraviolet lamp. The ultraviolet wavelength of the curing lamp is 200 - 280 nm, the light intensity is 50 - 200 W / cm², and the irradiation time is 1 - 200 s.

[0028] Here, the specific operation steps are as follows:

[0029] S1. Provide an N-type silicon substrate 1 and perform texturing treatment on it;

[0030] S2. Perform boron diffusion doping on the front side of the textured N-type silicon substrate 1 to form a P+ layer 2;

[0031] S3. Pickle the back side of the N-type silicon substrate 1 and perform alkali polishing;

[0032] S4. On the back of the N-type silicon substrate 1, form an SiO layer 5 and an N+ polysilicon layer 6 by CVD method at 500 - 900 °C;

[0033] S5. Remove the residual plated-around N+ polysilicon layer 6 on the front of the N-type silicon substrate 1 by RCA cleaning;

[0034] S6. Deposit an alumina thin film 3 on the surface of the N-type silicon substrate 1 by atomic layer deposition process, using trimethylaluminum and water as reactants in the process;

[0035] S7. Deposit a silicon nitride thin film on both the front and back of the N-type silicon substrate 1 by vapor deposition process;

[0036] S8. Cure the front of the N-type silicon substrate 1 with an ultraviolet curing lamp at room temperature;

[0037] S9. Perform screen printing, sintering and light injection treatment on the N-type silicon substrate 1 to obtain an N-TOPCON cell with anti-ultraviolet attenuation.

[0038] Here, after forming the alumina-silicon nitride stacked passivation layer in the TOPCON cell, high-energy short-wave ultraviolet light is used to preferentially break weak silicon-hydrogen bonds, and then through subsequent processes of sintering and light injection steps, free H+ is driven to form H2 overflow and enter the silicon matrix to form stable silicon-hydrogen bonds, so as to obtain stable low-density silicon-hydrogen bonds, while maintaining the passivation efficiency, reducing the ability of silicon-hydrogen bonds damaged by ultraviolet rays, reducing the influence of H+ on the passivation layer, and enhancing the anti-ultraviolet attenuation ability of the cell and module.

[0039] As a preferred embodiment, the temperature of the light injection is 200 - 600 °C, the time is 100 - 300 s, and the energy density is 1 - 5 W / cm².

[0040] Here, through subsequent high-temperature sintering and light injection of crystalline silicon, free H+ is produced to form H2 overflow, and finally a low-density strong silicon-hydrogen bond structure is obtained. After making the cell module, it is not easily damaged by ultraviolet rays during the light-induced power generation process, resulting in a decrease in power generation.

[0041] As a preferred embodiment, the pulse time of water and trimethylaluminum in the atomic layer deposition process is 10 - 30 s, the purge time is 10 - 30 s, the flow rates are both 20 - 40 sccm, the number of cycles is 30 - 50 times, and the reaction temperature is 280 - 310 °C.

[0042] Here, at a temperature of 250 - 350 °C, water and trimethylaluminum react to form a layer of alumina. The water process has more residual hydroxyl -OH in the alumina thin film 3 generated by water-based ALD, which can increase the H+ passivation ability and increase the density of Si-H bonds.

[0043] As a preferred embodiment, the thickness of the aluminum oxide film 3 is 3 - 10 nm.

[0044] Here, as the thickness of the aluminum oxide increases, the passivation performance becomes better, but the ultraviolet resistance performance under conventional processes will become worse. However, with the improvement of the process, the ultraviolet attenuation problem can be avoided because of the treatment with an ultraviolet lamp.

[0045] As a preferred embodiment, the refractive index of the silicon nitride film is 2.00 - 2.20, and the thickness is 70 - 90 nm.

[0046] Then, front and back silicon nitride is carried out on the silicon wafer with an aluminum oxide structure, and the front of the silicon wafer is irradiated with a high-power UV curing lamp to break a large number of weak silicon-hydrogen bonds in advance and turn them into free H⁺.

[0047] As a preferred embodiment, the curing treatment uses an ultraviolet LED array curing lamp.

[0048] Here, high-energy ultraviolet rays such as the UV-C band can be absorbed by the electrons in the silicon-hydrogen bonds, resulting in the breakage of the bonding structure. The high energy of the UV-C band will damage the silicon-hydrogen bonds in the passivation layer. A curing lamp with a deep ultraviolet LED array in the wavelength range of 10 - 300 nm is used, and the irradiation intensity is adjustable from 50 - 200 W / cm², directly acting on the Si-H bonds and defect states in the passivation layer of the aluminum oxide structure. Due to the higher energy of the short-wavelength UV-C, it is easier to trigger the dissociation of the silicon-hydrogen bonds.

[0049] As a preferred embodiment, texturing is to form a nano-level textured surface on the surface of the N-type silicon wafer.

[0050] This embodiment also provides an N-TOPCON battery structure, prepared by the preparation method of the above N-TOPCON battery structure, including an N-type silicon substrate 1, a P⁺ layer 2, an aluminum oxide film 3, and a silicon nitride film laminated in sequence from the inside to the outside on the front of the N-type silicon substrate 1, and an SiO layer 5, an N⁺ polysilicon layer 6, and a silicon nitride film laminated in sequence from the inside to the outside on the back of the N-type silicon substrate 1; the hydrogen ion concentration in the aluminum oxide film 3 is 10¹ 9 -10² 0 atoms / cm³.

[0051] As a preferred embodiment, the attenuation ratio threshold of the battery under UV60 kWh irradiation is ≤1.0%, and the attenuation ratio threshold of the battery module is ≤1.5%.

[0052] Here, UV60 kWh is the material weather resistance test standard, usually representing the total energy of ultraviolet irradiation in the test, and can quantitatively evaluate the anti-ultraviolet aging attenuation ability of the module.

[0053] Example 1

[0054] A preparation method of an N-TOPCON battery, comprising the following steps:

[0055] S1. Provide an N-type silicon substrate 1 and perform texturing treatment on it. The texturing treatment is to form a nano-level textured surface on the surface of the N-type silicon wafer;

[0056] S2. Perform boron diffusion doping on the front side of the textured N-type silicon substrate 1 to form a P+ layer 2;

[0057] S3. Pickle the back side of the N-type silicon substrate 1 and perform alkaline polishing;

[0058] S4. Use the CVD method to form a SiO layer 5 and an N+ polysilicon layer 6 on the back side of the N-type silicon substrate 1 at 500 °C;

[0059] S5. Remove the residual N+ polysilicon layer (6) plated around on the front side of the N-type silicon substrate 1 by RCA cleaning;

[0060] S6. Deposit an aluminum oxide film 3 on the surface of the N-type silicon substrate 1 by atomic layer deposition process. Trimethylaluminum and water are used as reactants in the process. The thickness of the aluminum oxide film 3 is 4 nm, and the hydrogen ion concentration of the aluminum oxide film 3 is 2×10¹ 9 atoms / cm³. The pulse time of water and trimethylaluminum in the atomic layer deposition process is 10 s, the purge time is 10 s, the flow rate is 20 sccm, the number of cycles is 30 times, and the reaction temperature is 300 °C;

[0061] S7. Deposit a silicon nitride film on both the front and back sides of the N-type silicon substrate 1 by chemical vapor deposition process. The refractive index of the silicon nitride film is 2.00 and the thickness is 70 nm;

[0062] S8. Cure the front side of the N-type silicon substrate 1 with an ultraviolet curing lamp at room temperature. The ultraviolet wavelength of the curing lamp is 200 nm, and the irradiation time is 10 s. The ultraviolet LED curing lamp is used for the curing treatment, and the light intensity of the curing lamp is 50 W / cm²;

[0063] S9. Perform screen printing, sintering and light injection treatment on the N-type silicon substrate 1 to obtain an N-TOPCON battery with anti-ultraviolet attenuation. The temperature of the light injection process is 200 °C, the time is 100 s, and the energy density of the light injection process is 2 W / cm².

[0064] Example 2

[0065] A preparation method of an N-TOPCON battery, comprising the following steps:

[0066] S1. Provide an N-type silicon substrate 1 and perform a texturing treatment on it. The texturing treatment is to form a nano-level textured surface on the surface of the N-type silicon wafer;

[0067] S2. Perform boron diffusion doping on the front side of the textured N-type silicon substrate 1 to form a P+ layer 2;

[0068] S3. Pickle the back side of the N-type silicon substrate 1 and perform alkaline polishing;

[0069] S4. Use the CVD method to form an SiO layer 5 and an N+ polysilicon layer 6 on the back side of the N-type silicon substrate 1 at 900 °C;

[0070] S5. Remove the residual deposited N+ polysilicon layer 6 on the front side of the N-type silicon substrate 1 by RCA cleaning;

[0071] S6. Deposit an alumina film 3 on the surface of the N-type silicon substrate 1 by atomic layer deposition process. Trimethylaluminum and water are used as reactants in the process. The thickness of the alumina film 3 is 6 nm, and the hydrogen ion concentration of the alumina film 3 is 4×10² 0 atoms / cm³. The pulse time of water and trimethylaluminum in the atomic layer deposition process is 15 s, the purge time is 15 s, the flow rate is 25 sccm, the number of cycles is 35 times, and the reaction temperature is 300 °C;

[0072] S7. Deposit a front nitride silicon film or a back nitride silicon film on the front and back sides of the N-type silicon substrate 1 by chemical vapor deposition process respectively. The refractive index of the nitride silicon film is 2.20 and the thickness is 75 nm;

[0073] S8. Cure the front side of the N-type silicon substrate 1 with an ultraviolet curing lamp at room temperature. The ultraviolet wavelength of the curing lamp is 250 nm, the irradiation time is 150 s, the ultraviolet LED curing lamp is used for the curing treatment, and the light intensity of the curing lamp is 100 W / cm²;

[0074] S9. Perform screen printing, sintering and light injection treatment on the N-type silicon substrate 1 to obtain an N-TOPCON battery with anti-ultraviolet attenuation. The temperature of the light injection process is 300 °C, the time is 150 s, and the energy density of the light injection process is 2 W / cm².

[0075] Example 3

[0076] A method for preparing an N-TOPCON battery, comprising the following steps:

[0077] S1. Provide an N-type silicon substrate 1 and perform a texturing treatment on it. The texturing treatment is to form a nano-level textured surface on the surface of the N-type silicon wafer;

[0078] S2. Perform boron diffusion doping on the front side of the textured N-type silicon substrate 1 to form a P+ layer 2;

[0079] S3. Pickle the back side of the N-type silicon substrate 1 and perform alkaline polishing.

[0080] S4. Use the CVD method to form the SiO layer 5 and the N+ polysilicon layer 6 on the back side of the N-type silicon substrate 1 at 550 °C.

[0081] S5. Remove the residual N+ polysilicon layer 6 plated around the front side of the N-type silicon substrate 1 by RCA cleaning.

[0082] S6. Deposit the alumina film 3 on the surface of the N-type silicon substrate 1 by atomic layer deposition process. Trimethylaluminum and water are used as reactants in the process. The thickness of the alumina film 3 is 7 nm, the hydrogen ion concentration of the alumina film 3 is 6×1019 atoms / cm³, the pulse time of water and trimethylaluminum in the atomic layer deposition process is 20 s, the purge time is 20 s, the flow rate is 30 sccm, the number of cycles is 40 times, and the reaction temperature is 300 °C.

[0083] S7. Deposit the silicon nitride film on both the front and back sides of the N-type silicon substrate 1 by vapor deposition process; the refractive index of the silicon nitride film is 2.00 and the thickness is 80 nm.

[0084] S8. Cure the front side of the N-type silicon substrate 1 with a UV curing lamp at room temperature. The UV wavelength of the curing lamp is 230 nm, the irradiation time is 100 s, the UV LED curing lamp is used for the curing treatment, and the light intensity of the curing lamp is 150 W / cm².

[0085] S9. Perform screen printing, sintering and light injection treatment on the N-type silicon substrate 1 to obtain the N-TOPCON cell with anti-UV attenuation. The temperature of the light injection process is 400 °C, the time is 200 s, and the energy density of the light injection process is 3 W / cm².

[0086] Example 4

[0087] A preparation method of an N-TOPCON cell includes the following steps:

[0088] S1. Provide the N-type silicon substrate 1 and perform texturing treatment on it. The texturing treatment is to form a nano-level textured surface on the surface of the N-type silicon wafer.

[0089] S2. Perform boron diffusion doping on the front side of the textured N-type silicon substrate 1 to form the P+ layer 2.

[0090] S3. Pickle the back side of the N-type silicon substrate 1 and perform alkaline polishing.

[0091] S4. Use the CVD method to form the SiO layer 5 and the N+ polysilicon layer 6 on the back side of the N-type silicon substrate 1 at 600 °C.

[0092] S5. Remove the deposited N+ polysilicon layer 6 remaining on the front side of the N-type silicon substrate 1 by RCA cleaning;

[0093] S6. Deposit an aluminum oxide film 3 on the surface of the N-type silicon substrate 1 by atomic layer deposition. Trimethylaluminum and water are used as reactants in the process. The thickness of the aluminum oxide film 3 is 8 nm, the hydrogen ion concentration of the aluminum oxide film 3 is 8×1019 atoms / cm³, the pulse time of water and trimethylaluminum in the atomic layer deposition process is 25 s, the purge time is 25 s, the flow rate is 35 sccm, the number of cycles is 45 times, and the reaction temperature is 300 °C;

[0094] S7. Deposit a silicon nitride film on both the front and back sides of the N-type silicon substrate 1 by chemical vapor deposition. The refractive index of the silicon nitride film is 2.00 and the thickness is 8 nm;

[0095] S8. Cure the front side of the N-type silicon substrate 1 with an ultraviolet curing lamp at room temperature. The ultraviolet wavelength of the curing lamp is 250 nm, the irradiation time is 150 s, the ultraviolet LED curing lamp is used for the curing treatment, and the light intensity of the curing lamp is 180 W / cm²;

[0096] S9. Perform screen printing, sintering, and optical injection treatment on the N-type silicon substrate 1 to obtain an N-TOPCON cell with anti-ultraviolet attenuation. The temperature of the optical injection process is 500 °C, the time is 250 s, and the energy density of the optical injection process is 4 W / cm².

[0097] Example 5

[0098] A method for preparing an N-TOPCON cell, comprising the following steps:

[0099] S1. Provide an N-type silicon substrate 1 and perform texturing treatment on it. The texturing treatment is to form a nanoscale textured surface on the surface of the N-type silicon wafer;

[0100] S2. Perform boron diffusion doping on the front side of the textured N-type silicon substrate 1 to form a P+ layer 2;

[0101] S3. Pickle the back side of the N-type silicon substrate 1 and perform alkaline polishing;

[0102] S4. Form an SiO layer 5 and an N+ polysilicon layer 6 on the back side of the N-type silicon substrate 1 by CVD method at 900 °C;

[0103] S5. Remove the deposited N+ polysilicon layer 6 remaining on the front side of the N-type silicon substrate 1 by RCA cleaning;

[0104] S6. Deposit an aluminum oxide film 3 on the surface of the N-type silicon substrate 1 by atomic layer deposition. Trimethylaluminum and water are used as reactants in the process. The thickness of the aluminum oxide film 3 is 10 nm, and the hydrogen ion concentration of the aluminum oxide film 3 is 10² 0 atoms / cm³. The pulse time of water and trimethylaluminum in the atomic layer deposition process is 30 s, the purge time is 30 s, the flow rate is 40 sccm, the number of cycles is 50 times, and the reaction temperature is 300 °C;

[0105] S7. Deposit silicon nitride films on both the front and back of the N-type silicon substrate by chemical vapor deposition. The refractive index of the silicon nitride film is 2.20, and the thickness is 90 nm;

[0106] S8. Cure the front of the N-type silicon substrate 1 at room temperature using an ultraviolet curing lamp. The ultraviolet wavelength of the curing lamp is 280 nm, the irradiation time is 200 s, the ultraviolet LED curing lamp is used for the curing treatment, and the light intensity of the curing lamp is 200 W / cm²;

[0107] S9. Perform screen printing, sintering, and light injection treatment on the N-type silicon substrate 1 to obtain an N-TOPCON cell with ultraviolet attenuation resistance. The temperature of the light injection process is 600 °C, the time is 300 s, and the energy density of the light injection process is 5 W / cm².

[0108] Comparative Example 1

[0109] A method for preparing an N-TOPCON cell includes the following steps:

[0110] S1. Provide the N-type silicon substrate 1 and perform texturing treatment on it. The texturing treatment is to form a nano-level textured surface on the surface of the N-type silicon wafer;

[0111] S2. Perform boron diffusion doping on the front of the textured N-type silicon substrate 1 to form a P+ layer 2;

[0112] S3. Pickle the back of the N-type silicon substrate 1 and perform alkaline polishing;

[0113] S4. Sequentially form an SiO layer 5 and an N+ polysilicon layer 6 on the back of the N-type silicon substrate 1 at high temperature;

[0114] S5. Remove the residual N+ polysilicon layer 6 on the front of the N-type silicon substrate 1 by RCA cleaning;

[0115] S6. Deposit an aluminum oxide film 3 on the surface of the N-type silicon substrate 1 using atomic layer deposition. Trimethylaluminum and water are used as reactants in the process. The thickness of the aluminum oxide film 3 is 3.5 nm, the hydrogen ion concentration of the aluminum oxide film 3 is 1.6×10¹⁹ atoms / cm³, the pulse time of water and trimethylaluminum in the atomic layer deposition process is 5 s, the purge time is 5 s, the flow rate is 10 sccm, and the number of cycles is 5 times;

[0116] S7. Deposit a silicon nitride film on both the front and back of the N-type silicon substrate 1 using chemical vapor deposition. The refractive index of the silicon nitride film is 2.00 and the thickness is 70 nm;

[0117] S8. Perform screen printing, sintering, and light injection on the N-type silicon substrate 1 to obtain an N-TOPCON cell with ultraviolet attenuation resistance. The temperature of the light injection process is 200 °C, the time is 100 s, and the energy density of the light injection process is 1 W / cm².

[0118] Comparative Example 2

[0119] A method for preparing an N-TOPCON cell, comprising the following steps:

[0120] S1. Provide an N-type silicon substrate 1 and perform texturing treatment on it. The texturing treatment is to form a nanoscale textured surface on the surface of the N-type silicon wafer;

[0121] S2. Perform boron diffusion doping on the front of the textured N-type silicon substrate 1 to form a P⁺ layer 2;

[0122] S3. Pickle the back of the N-type silicon substrate 1 and perform alkaline polishing;

[0123] S4. Sequentially form an SiO layer 5 and an N⁺ polysilicon layer 6 on the back of the N-type silicon substrate 1 at high temperature;

[0124] S5. Remove the residual plated N⁺ polysilicon layer 6 on the front of the N-type silicon substrate 1 by RCA cleaning;

[0125] S6. Deposit an aluminum oxide film 3 on the surface of the N-type silicon substrate 1 using atomic layer deposition. Trimethylaluminum and water are used as reactants in the process. The thickness of the aluminum oxide film 3 is 4.5 nm, the hydrogen ion concentration of the aluminum oxide film 3 is 3×10¹⁹ atoms / cm³, the pulse time of water and trimethylaluminum in the atomic layer deposition process is 8 s, the purge time is 8 s, the flow rate is 15 sccm, and the number of cycles is 25; [[ID=j]]

[0126] S7. Deposit a silicon nitride film on both the front and back of the N-type silicon substrate 1 using chemical vapor deposition. The refractive index of the silicon nitride film is 2.00 and the thickness is 75 nm;

[0127] S8. Screen print, sinter, and perform photo-injection treatment on the N-type silicon substrate 1 to obtain an N-TOPCON cell with anti-ultraviolet attenuation. The temperature of the photo-injection process is 300 °C, the time is 150 s, and the energy density of the photo-injection process is 2 W / cm².

[0128] Comparative Example 3

[0129] A method for preparing an N-TOPCON cell, comprising the following steps:

[0130] S1. Provide the N-type silicon substrate 1 and perform texturing treatment on it. The texturing treatment is to form a nano-level textured surface on the surface of the N-type silicon wafer;

[0131] S2. Perform boron diffusion doping on the front side of the textured N-type silicon substrate 1 to form a P+ layer 2;

[0132] S3. Pickle the back side of the N-type silicon substrate 1 and perform alkaline polishing;

[0133] S4. Sequentially form an SiO layer 5 and an N+ polysilicon layer 6 on the back side of the N-type silicon substrate 1 at high temperature;

[0134] S5. Remove the residual plated N+ polysilicon layer 6 on the front side of the N-type silicon substrate 1 by RCA cleaning;

[0135] S6. Deposit an alumina film 3 on the surface of the N-type silicon substrate 1 by atomic layer deposition process. Trimethylaluminum and water are used as reactants in the process. The thickness of the alumina film 3 is 5.8 nm, the hydrogen ion concentration of the alumina film 3 is 5×10¹⁹ atoms / cm³, the pulse time of water and trimethylaluminum in the atomic layer deposition process is 11, the purge time is 11 s, the flow rate is 20 sccm, and the number of cycles is 30 times;

[0136] S7. Deposit a silicon nitride film on both the front and back sides of the N-type silicon substrate 1 by chemical vapor deposition process; the refractive index of the silicon nitride film is 2.00 and the thickness is 80 nm;

[0137] S8. Screen print, sinter, and perform photo-injection treatment on the N-type silicon substrate 1 to obtain an N-TOPCON cell with anti-ultraviolet attenuation. The temperature of the photo-injection process is 400 °C, the time is 200 s, and the energy density of the photo-injection process is 3 W / cm².

[0138] Comparative Example 4

[0139] A method for preparing an N-TOPCON cell, comprising the following steps:

[0140] S1. Provide the N-type silicon substrate 1 and perform texturing treatment on it. The texturing treatment is to form a nano-level textured surface on the surface of the N-type silicon wafer;

[0141] S2. Perform boron diffusion doping on the front side of the N-type silicon substrate 1 after texturing to form the P+ layer 2;

[0142] S3. Pickle the back side of the N-type silicon substrate 1 and perform alkaline polishing;

[0143] S4. Sequentially form the SiO layer 5 and the N+ polysilicon layer 6 on the back side of the N-type silicon substrate 1 at high temperature;

[0144] S5. Remove the residual plated N+ polysilicon layer 6 on the front side of the N-type silicon substrate 1 by RCA cleaning;

[0145] S6. Deposit an aluminum oxide film 3 on the surface of the N-type silicon substrate 1 by atomic layer deposition process. Trimethylaluminum and water are used as reactants in the process. The thickness of the aluminum oxide film 3 is 6.5 nm, the hydrogen ion concentration of the aluminum oxide film 3 is 6.5×1019 atoms / cm³, the pulse time of water and trimethylaluminum in the atomic layer deposition process is 35 s, the purge time is 35 s, the flow rate is 25 sccm, and the number of cycles is 14 times;

[0146] S7. Deposit silicon nitride films on both the front and back sides of the N-type silicon substrate 1 by chemical vapor deposition process; the refractive index of the silicon nitride film is 2.00 and the thickness is 85 nm;

[0147] S8. Perform screen printing, sintering and photo-injection treatment on the N-type silicon substrate 1 to obtain an N-TOPCON cell with anti-ultraviolet attenuation. The temperature of the photo-injection process is 500 °C, the time is 250 s, and the energy density of the photo-injection process is 4 W / cm².

[0148] Comparative Example 5

[0149] A preparation method of an N-TOPCON cell, comprising the following steps:

[0150] S1. Provide the N-type silicon substrate 1 and perform texturing treatment on it. The texturing treatment is to form a nano-level textured surface on the surface of the N-type silicon wafer;

[0151] S2. Perform boron diffusion doping on the front side of the N-type silicon substrate 1 after texturing to form the P+ layer 2;

[0152] S3. Pickle the back side of the N-type silicon substrate 1 and perform alkaline polishing;

[0153] S4. Sequentially form the SiO layer 5 and the N+ polysilicon layer 6 on the back side of the N-type silicon substrate 1 at high temperature;

[0154] S5. Remove the residual plated N+ polysilicon layer (6) on the front side of the N-type silicon substrate 1 by RCA cleaning;

[0155] S6. Deposit an aluminum oxide film 3 on the surface of the N-type silicon substrate 1 using atomic layer deposition. Trimethylaluminum and water are used as reactants in the process. The thickness of the aluminum oxide film 3 is 15 nm, the hydrogen ion concentration of the aluminum oxide film 3 is 8×10¹⁹ atoms / cm³, the pulse time of water and trimethylaluminum in the atomic layer deposition process is 40 s, the purge time is 40 s, the flow rate is 30 sccm, and the number of cycles is 15 times.

[0156] S7. Deposit silicon nitride films on both the front and back of the N-type silicon substrate 1 using chemical vapor deposition. The refractive index of the silicon nitride film is 2.00 and the thickness is 90 nm.

[0157] S8. Perform screen printing, sintering, and light injection on the N-type silicon substrate 1 to obtain an N-TOPCON cell with anti-ultraviolet attenuation. The temperature of the light injection process is 600 °C, the time is 300 s, and the energy density of the light injection process is 5 W / cm².

[0158] Next, the N-TOPCON cell structures obtained by the above 1-5 groups of examples and 1-5 groups of comparative methods are tested for performance, and the results are as follows:

[0159] Table 1 Performance test results of N-TOPCON cell structures prepared in each example and comparative example

[0160] Project UV light exposure time (S) UV light intensity (W / m²) UV light wavelength (nm) Pulse time (s) Purge time (s) Process flow rate (sccm) Number of cycles (times) Aluminum oxide thickness (nm) UV attenuation resistance value (UV60kwh) Example 1 10 50 200 10 10 20 30 4 1.00% Example 2 150 100 250 15 15 25 35 6 0.80% Example 3 100 150 230 20 20 30 40 7 0.70% Example 4 150 180 250 25 25 35 45 8 0.65% Example 5 200 200 280 30 30 40 50 10 0.60% Comparative Example 1 0 0 0 5 5 10 5 3.5 1.50% Comparative Example 2 0 0 0 8 8 15 25 4.5 1.30% Comparative Example 3 0 0 0 11 11 20 30 5.8 1.20% Comparative Example 4 0 0 0 35 35 25 14 6.5 1.15% Comparative Example 5 0 0 0 40 40 30 15 15 1.10%

[0161] Referring to Table 1, after adding the use of an ultraviolet curing lamp to cure the front of the N-type silicon substrate in the production process of the N-TOPCON cell, at different UV light intensities, as the intensity increases, the UV attenuation decreases, and the UV attenuation of the cell is lower than that of the conventional process. At the same time, the formation of the aluminum oxide structure can greatly reduce the UV attenuation loss of the cell and the module, ensuring the continuous power generation ability of the module.

[0162] The above is only the preferred embodiment of the present invention and is not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of an N-TOPCON battery, comprising texturing, boron diffusion doping, alkaline polishing, forming an SiO layer (5) and an N+ polysilicon layer (6), RCA cleaning, ALD alumina film (3), depositing a silicon nitride film, screen printing, sintering, and optical injection on an N-type silicon substrate (1), characterized in that, The ALD alumina film (3) is deposited on the surface of the N-type silicon substrate (1) by atomic layer deposition process to deposit an alumina film (3), using trimethylaluminum and water as reactants, and the hydrogen ion concentration of the deposited alumina film (3) is 10¹ 9 -10² 0 atoms / cm³; Before the screen printing, an ultraviolet lamp curing treatment is added. At room temperature, the front surface of the N-type silicon substrate (1) is cured using an ultraviolet lamp. The ultraviolet wavelength of the curing lamp is 200 - 280 nm, the light intensity is 50 - 200 W / cm², and the irradiation time is 1 - 200 s.

2. The preparation method of an N-TOPCON battery according to claim 1, wherein The temperature of the photo-injection is 200 - 600 °C, the time is 100 - 300 s, and the energy density is 1 - 5 W / cm².

3. The preparation method of an N-TOPCON battery according to claim 1, characterized in that, In the atomic layer deposition process, the pulse time of water and trimethylaluminum is 10 - 30 s, the purge time is 10 - 30 s, the flow rates are both 20 - 40 sccm, the number of cycles is 30 - 50 times, and the reaction temperature is 280 - 310 °C.

4. The preparation method of an N-TOPCON battery according to claim 1, characterized in that, The thickness of the aluminum oxide film (3) is 3 - 10 nm.

5. The preparation method of an N-TOPCON battery according to claim 1, characterized in that The refractive index of the silicon nitride film is 2.00 - 2.20, and the thickness is 70 - 90 nm.

6. The preparation method of an N-TOPCON battery according to claim 1, wherein, The curing treatment uses an ultraviolet LED array curing lamp.

7. The preparation method of an N-TOPCON battery according to claim 1, wherein, The texturing is to form a nano-scale textured surface on the surface of the N-type silicon wafer.

8. An N-TOPCON battery structure, characterized in that, Prepared by the preparation method of the N-TOPCON battery structure according to any one of claims 1-5, including an N-type silicon substrate (1), a P+ layer (2), an aluminum oxide film (3), and a front-side silicon nitride film (4) stacked in sequence from the inside to the outside on the front side of the N-type silicon substrate (1), and an SiO layer (5), an N+ polysilicon layer (6), and a back-side silicon nitride film (7) stacked in sequence from the inside to the outside on the back side of the N-type silicon substrate (1); the hydrogen ion concentration in the aluminum oxide film (3) is 10¹ 9 -10² 0 atoms / cm³.

9. The N-TOPCON battery structure according to claim 8, characterized in that, Under the irradiation of UV 60 kWh, the attenuation ratio threshold of the battery in the battery structure is ≤ 1.0%, and the attenuation ratio threshold of the battery module is ≤ 1.5%.

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