Solar cell and preparation method therefor

Abstract

A solar cell. The solar cell comprises a passivation anti-reflection film structure (1), and the passivation anti-reflection film structure (1) comprises an aluminum oxide film (10) and at least one layer of silicon nitride film (20), which are sequentially arranged from inside to outside in a stacked manner, wherein the thickness of the aluminum oxide film (10) is greater than or equal to 5 nm; the silicon nitride film (20) comprises at least one first film (20a), and the refractive index of the first film (20a) is greater than or equal to 2.3; and when the thickness of the aluminum oxide film (10) is increased by 1 nm, the refractive index of the first film (20a) is increased by 0.03-0.06.

Description

Solar cell and method for manufacturing the same

[0001] Related applications

[0002] This application claims priority to Chinese patent application number 202410355181.3, filed on March 27, 2024, entitled “Solar Cells and Methods for Making Them,” the entire text of which is hereby incorporated by reference. Technical Field

[0003] The present application relates to the technical field of solar cells, and in particular to a solar cell and a method for preparing the same. Background Art

[0004] To prevent carrier recombination at defects and increase minority carrier lifetime, solar cell surfaces are typically passivated with a dielectric layer. However, UV exposure to solar cells increases the number of recombination centers at the interface between the silicon wafer and the passivation layer, altering the fixed charge density and increasing the density of interface defects near the wafer surface. This damages the surface passivation structure of the solar cell, leading to a decrease in the solar cell's photoelectric conversion efficiency. Existing solar cell output power has an ultraviolet light-induced degradation rate of >20%. While the use of glass and ethylene-vinyl acetate (EVA) encapsulation for solar cell modules can mitigate the effects of UV exposure, a certain degree of UV-induced degradation still exists, hindering the solar cell's photoelectric conversion efficiency. Therefore, there is a need for a solar cell that can significantly reduce UV-induced degradation.

[0005] Summary of the Invention

[0006] According to various embodiments of the present application, a solar cell is provided, whose passivation anti-reflection film structure can improve the passivation interface loss of the solar cell caused by ultraviolet radiation, and achieve an attenuation rate of 50kWh ultraviolet radiation of less than 1%, which greatly improves the light irradiation stability of the solar cell and effectively ensures the photoelectric conversion efficiency of the solar cell.

[0007] A solar cell includes a passivation anti-reflection film structure, wherein the passivation anti-reflection film structure comprises: an aluminum oxide film and at least one silicon nitride film stacked sequentially from the inside out; wherein the thickness of the aluminum oxide film is ≥5nm, the silicon nitride film includes at least one first film, and the refractive index of the first film is ≥2.3, and the material of the first film is silicon nitride; and, for every 1nm increase in the thickness of the aluminum oxide film, the refractive index of the first film increases by 0.03 to 0.06.

[0008] In one embodiment, the N / Si atomic ratio of the first film is ≤4:1.

[0009] In one embodiment, when the thickness of the aluminum oxide film increases by 1 nm, the N / Si atomic ratio of the first film decreases by 0.3:1 to 0.6:1.

[0010] In one embodiment, the refractive index of the silicon nitride film is ≥2.3.

[0011] In one embodiment, the thickness of the aluminum oxide film is less than 13 nm;

[0012] And / or, the refractive index of any layer of the silicon nitride film is ≤4.0.

[0013] A method for preparing the solar cell as described above, wherein the method for preparing the passivation anti-reflection film structure in the solar cell comprises the following steps:

[0014] S1. Deposition of aluminum oxide film: Place the silicon wafer after oxidation annealing in a deposition device, introduce trimethylaluminum and water in the gas phase in sequence as one cycle of deposition, and perform X cycles of deposition, where X ≥ 50;

[0015] S2. Deposit silicon nitride film: Place the silicon wafer after aluminum oxide film deposition into a deposition device, first introduce silane and nitrous oxide to deposit silicon oxide, then introduce silane and ammonia to nitride the silicon oxide, wherein the flow rate of ammonia is Ysccm, and Y=15502.5-119.25X.

[0016] In one embodiment, in the step of introducing trimethylaluminum, the temperature is 220° C. to 300° C., the time is 7 seconds to 15 seconds, the pressure is 25 torr to 50 torr, and the flow rate of trimethylaluminum is 5000 sccm to 8000 sccm.

[0017] In one embodiment, in the step of introducing water, the temperature is 220° C. to 300° C., the time is 6.5 s to 15 s, the pressure is 25 torr to 50 torr, and the flow rate of water is 6000 sccm to 10000 sccm.

[0018] In one embodiment, in the step of depositing silicon oxide, the time is 20s to 50s, the temperature is 500°C to 600°C, the pressure is 240Pa to 500Pa, the flow rate of silane is 1380sccm to 5000sccm, and the flow rate of nitrous oxide is 6450sccm to 10000sccm.

[0019] In one embodiment, in the step of nitriding silicon oxide, the time is 20s to 50s, the temperature is 500°C to 60°C, the pressure is 230Pa to 500Pa, the flow rate of silane is 2500sccm to 5000sccm, and the flow rate of ammonia is 7500sccm to 10000sccm.

[0020] The above-mentioned solar cell passivation anti-reflection film structure, through the synergistic effect of an aluminum oxide film of a specific thickness and a silicon nitride film of a specific refractive index, on the one hand reduces the ultraviolet radiation incident at the interface between the silicon wafer and the passivation layer, effectively reducing the interface defect density near the silicon wafer surface; on the other hand, it increases the bond energy of Si-H bonds and NH bonds, reduces the number of broken H bonds and dangling bonds, thereby reducing carrier recombination, increasing the minority carrier lifetime, and effectively ensuring the passivation photoelectric conversion efficiency of the solar cell surface. Therefore, the passivation anti-reflection film structure described in this application can significantly reduce the ultraviolet light attenuation of the solar cell, achieving an attenuation rate of less than 1% for 50kWh ultraviolet radiation, greatly improving the light irradiation stability of the solar cell, and effectively ensuring the photoelectric conversion efficiency of the solar cell.

[0021] The details of one or more embodiments of the present application are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the present application will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to better describe and illustrate the embodiments and / or examples of the inventions disclosed herein, reference may be made to one or more of the accompanying drawings. The additional details or examples used to describe the accompanying drawings should not be considered to limit the scope of the disclosed inventions, the presently described embodiments and / or examples, and any of the best modes currently understood for these inventions.

[0023] FIG1 shows a passivation anti-reflection film structure of a solar cell in one embodiment of the present application.

[0024] FIG2 shows a passivation anti-reflection film structure of a solar cell in one embodiment of the present application.

[0025] FIG3 shows a passivation anti-reflection film structure of a solar cell in one embodiment of the present application.

[0026] Reference numerals: 1, passivation anti-reflection film structure; 10, aluminum oxide film; 20, silicon nitride film; 20a, first film; 20b, second film. DETAILED DESCRIPTION

[0027] To facilitate understanding of the present application, the present application will be described in more detail below. However, it should be understood that the present application can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the understanding of the disclosure of the present application more thorough and comprehensive.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the technical field of the present application. The terms used herein in the specification of the present application are only for the purpose of describing specific embodiments or embodiments and are not intended to limit the present application. The optional scope of the term "and / or" used herein includes any one of two or more related listed items, and also includes any and all combinations of related listed items, including any two related listed items, any more related listed items, or a combination of all related listed items.

[0029] After extensive and in-depth research, the applicant discovered that UV-induced degradation in solar cells is primarily due to UV radiation causing an increase in broken H bonds within the solar cell, leading to the formation of excessive H atom clusters at the interface between the silicon wafer and the passivation layer. This promotes carrier recombination, which deteriorates the solar cell's passivation-to-photovoltaic conversion efficiency. Existing solutions to UV-induced degradation in solar cells typically involve absorbing or converting UV light through glass or EVA film, primarily through optimization of the photovoltaic module's encapsulation materials. These solutions fail to address the source or nature of UV-induced degradation in solar cells.

[0030] Therefore, the present application provides a solar cell, including a passivation anti-reflection film structure, the passivation anti-reflection film structure includes an aluminum oxide film and at least one silicon nitride film stacked in sequence from the inside to the outside; wherein, the thickness of the aluminum oxide film is ≥5nm, there is a first film in the silicon nitride film, and the refractive index of the first film is ≥2.3, and the material of the first film is silicon nitride; and, when the thickness of the aluminum oxide film increases by 1nm, the refractive index of the first film increases by 0.03 to 0.06.

[0031] The solar cell passivation anti-reflection film structure, through the synergistic effect of an aluminum oxide film of a specific thickness and a silicon nitride film of a specific refractive index, on the one hand, reduces the ultraviolet radiation incident at the interface between the silicon wafer and the passivation layer, effectively reducing the interface defect density near the silicon wafer surface; on the other hand, it increases the bond energy of Si-H bonds and NH bonds, reduces the number of broken H bonds and dangling bonds, thereby reducing carrier recombination, increasing the minority carrier lifetime, and effectively ensuring the passivation photoelectric conversion efficiency of the solar cell surface. Therefore, the passivation anti-reflection film structure of the present application can significantly reduce the ultraviolet light attenuation of the solar cell, achieving an attenuation rate of less than 1% for 50kWh ultraviolet radiation, greatly improving the light irradiation stability of the solar cell, and effectively ensuring the photoelectric conversion efficiency of the solar cell.

[0032] It should be noted that both the front and back sides of the solar cell may be affected by ultraviolet-induced attenuation. The passivation anti-reflection film structure of the present application can be applied to the front side of the solar cell alone, or to the back side of the solar cell alone, or to the back side of the solar cell at the same time. The passivation anti-reflection film structure of the present application is particularly suitable for the front side of the solar cell, that is, the photosensitive side; the solar cells of the present application include but are not limited to crystalline silicon solar cells such as PERC and TOPCon.

[0033] Referring to Figures 1 to 3, it can be understood that when the number of layers of the silicon nitride film is one, the silicon nitride film is the first film; when the number of layers of the silicon nitride film is greater than one, the refractive index of each layer of the silicon nitride film can be the same or different, and the refractive index of each layer of the silicon nitride film except the first film can be ≥2.3 or <2.3, and there is no limitation on the stacking position relationship of the first film and other silicon nitride film layers. In other words, the silicon nitride film 20 includes a first film 20a and a second film 20b, and the materials of the first film 20a and the second film 20b are both silicon nitride. Among them, the refractive index of the first film 20a is ≥2.3, and the refractive index of the second film 20b can be ≥2.3 or <2.3; and the number of layers of the first film 20a is defined as M, and the number of layers of the second film 20b is defined as N, and M and N satisfy the relationship: M≥1, N≥0.

[0034] In one embodiment, in order to further increase the bond energy of Si-H bonds and NH bonds in the silicon nitride film, reduce the cracking caused by ultraviolet light, and reduce the ultraviolet light incident on the interface between the silicon wafer and the passivation layer, while reducing the light reflection loss of the solar cell, the N / Si atomic ratio of the first film can be ≤4:1.

[0035] It can be understood that when the number of silicon nitride film layers is greater than one, the N / Si atomic ratio of each silicon nitride film layer can be the same or different, and the N / Si atomic ratio of each silicon nitride film layer except the first film can be ≤4:1 or >4:1.

[0036] In one embodiment, when the thickness of the aluminum oxide film increases by 1 nm, the N / Si atomic ratio of the first film decreases by 0.3:1 to 0.6:1, so as to further improve the ultraviolet light-induced degradation of the solar cell and ensure the photoelectric conversion efficiency of the solar cell.

[0037] In one embodiment, the refractive index of all silicon nitride films is ≥2.3, which further improves the ultraviolet light-induced degradation of the solar cell and ensures the photoelectric conversion efficiency of the solar cell.

[0038] In one embodiment, the thickness of the aluminum oxide film is less than 13 nm, which increases the negative charge density at the interface between the aluminum oxide film and the silicon substrate, reduces the rate of recombination of photogenerated carriers on the surface, improves the field effect passivation effect, and at the same time, effectively blocks the entry of ultraviolet rays and reduces the damage of high-energy ultraviolet light to the passivation interface of the solar cell.

[0039] In one embodiment, the refractive index of any layer of the silicon nitride film is ≤4.0, and the film has good optical / electrical properties and anti-reflection effects, effectively ensuring the maximum electrical power of the solar cell.

[0040] The present application also provides a method for preparing the solar cell as described above, wherein the method for preparing the passivation anti-reflection film structure in the solar cell comprises the following steps:

[0041] S1. Deposition of aluminum oxide film: Place the silicon wafer after oxidation annealing in a deposition device, introduce trimethylaluminum and water in the gas phase in sequence as one cycle of deposition, and perform X cycles of deposition, where X ≥ 50;

[0042] S2. Deposit silicon nitride film: Place the silicon wafer after aluminum oxide film deposition into a deposition device, first introduce silane and nitrous oxide to deposit silicon oxide, then introduce silane and ammonia to nitride the silicon oxide, wherein the flow rate of ammonia is Ysccm, and Y=15502.5-119.25X.

[0043] It can be understood that X<130, that is, the number of cyclic deposition is less than 130 times.

[0044] In the above preparation method, by controlling the number of deposition cycles when depositing aluminum oxide and the ammonia flow rate when depositing silicon nitride, a specific thickness of aluminum oxide and a specific Si / N atomic ratio and refractive index of silicon nitride are achieved. Therefore, the synergistic effect of the aluminum oxide film of specific thickness and the silicon nitride film of specific refractive index significantly reduces the ultraviolet light attenuation of the solar cell, achieving an attenuation rate of <1% for 50kWh ultraviolet radiation, greatly improving the light irradiation stability of the solar cell and effectively ensuring the photoelectric conversion efficiency of the solar cell.

[0045] The deposition equipment in steps S1 and S2 includes but is not limited to atomic layer vapor deposition (ALD) equipment and plasma enhanced chemical vapor deposition (PECVD) equipment, and steps S1 and S2 can use the same deposition equipment or different deposition equipment.

[0046] In one embodiment, when the silicon wafer after oxidation annealing is placed in a deposition device, vacuum is evacuated and leak detection is performed. The vacuum evacuation time is 500s to 600s, the temperature is 220°C to 250°C, and the pressure is 30 torr to 80 torr to ensure the subsequent silicon oxide deposition effect.

[0047] In one embodiment, before introducing trimethylaluminum and water in the gas phase for cyclic deposition, pre-gassing is performed, with the flow rate of trimethylaluminum being 10,000 sccm to 20,000 sccm, and the flow rate of water being 10,000 sccm to 20,000 sccm.

[0048] In one embodiment, in the step of introducing trimethylaluminum, the temperature is 220° C. to 300° C., the time is 7 seconds to 15 seconds, the pressure is 25 torr to 50 torr, and the flow rate of trimethylaluminum is 5000 sccm to 8000 sccm.

[0049] Illustratively, before the step of introducing water, trimethylaluminum is purged for 6.5s to 15s, the temperature is 220°C to 300°C, the pressure is 25torr to 50torr, the flow rate of trimethylaluminum is 10,000sccm to 15,000sccm, and the flow rate of water is 10,000sccm to 20,000sccm.

[0050] In one embodiment, in the step of introducing water, the temperature is 220° C. to 300° C., the time is 6.5 s to 15 s, the pressure is 25 torr to 50 torr, and the flow rate of water is 6000 sccm to 10000 sccm.

[0051] Illustratively, before the step of introducing trimethylaluminum in the second cycle, the water is purged for 4s to 15s, the temperature is 220°C to 300°C, the pressure is 25 torr to 50 torr, the flow rate of trimethylaluminum is 10,000 sccm to 15,000 sccm, and the flow rate of water is 10,000 sccm to 20,000 sccm.

[0052] In one embodiment, when the silicon wafer after aluminum oxide film deposition is placed in a deposition device, vacuuming is performed and leak detection is performed. The vacuuming time is 200s to 300s and the temperature is 500° C. to 600° C. to ensure the subsequent silicon oxide deposition effect.

[0053] In one embodiment, the step of depositing silicon oxide is performed for 20 to 50 seconds, at a temperature of 500° C. to 600° C., at a pressure of 240 Pa to 500 Pa, with a silane flow rate of 1380 sccm to 5000 sccm and a nitrous oxide flow rate of 6450 sccm to 10000 sccm. The nitrous oxide can act as a current carrier and dilution agent.

[0054] Exemplarily, the radio frequency power of the deposition equipment is 12600W to 25000W, and the pulse on-off ratio is 2 / 30 to 50 / 100.

[0055] In one embodiment, in the step of nitriding silicon oxide, the time is 20s to 50s, the temperature is 500°C to 600°C, the pressure is 230Pa to 500Pa, the flow rate of silane is 2500sccm to 5000sccm, and the flow rate of ammonia is 7500sccm to 10000sccm.

[0056] Exemplarily, the radio frequency power of the deposition equipment is 14500W to 25000W, and the pulse on-off ratio is 4 / 60 to 50 / 100.

[0057] It can be understood that when the number of layers of the silicon nitride film is greater than one, after the deposition of the first layer of silicon nitride film is completed, the steps of first introducing silane and nitriding gas to deposit silicon oxide and then introducing silane and ammonia to nitride the silicon oxide can be repeated, and new process parameters, such as microwave power, temperature and gas flow ratio, can be adopted to achieve silicon nitride films with different N / Si atomic ratios and refractive indices, which is beneficial to improve the passivation effect of the passivation anti-reflection film, and improve the anti-reflection effect of the passivation anti-reflection film, thereby improving the photoelectric conversion efficiency of the solar cell.

[0058] It should be noted that the present application does not make any requirements on the structure of the back of the solar cell. The passivation structure of the back of the PERC cell or the passivation contact structure of the back of the TOPCon cell can be used. The back structure of the solar cell is prepared using the existing method, which is not described in detail in the present application. When the passivation anti-reflection film of the present application is used on both the front and back sides, the passivation anti-reflection film structures on the front and back sides can be the same or different.

[0059] In one embodiment, after the silicon nitride deposition is completed, the silicon wafer can be prepared into a solar cell through processes such as screen printing of metal electrodes and sintering.

[0060] Hereinafter, the solar cell and the preparation method thereof will be further described through the following specific embodiments.

[0061] Example 1

[0062] S1. Deposition of aluminum oxide on the front:

[0063] (1) Boat loading: Place the silicon wafer after texturing and diffusion on an aluminum fixture and send it into the ALD equipment by a robotic arm. The time is set to 120 seconds and the temperature is set to 250°C.

[0064] (2) Vacuuming: The furnace tube is vacuumed for the first time for 200 s, at a temperature of 220 °C and a pressure of 30 torr;

[0065] (3) Heating: The pressure is evacuated to the process setting value, and the furnace tube is kept at a constant temperature for 300 seconds, the temperature is set at 220°C, and the pressure is 30 torr;

[0066] (4) Leak detection: Test whether there is vacuum leakage, the time is 20s, the temperature is 220℃, and the pressure is 30torr;

[0067] (5) Pre-gassing: pre-gas the gas line for 10 s, with a trimethylaluminum flow rate of 10,000 sccm and a water flow rate of 10,000 sccm;

[0068] (6) Trimethylaluminum was introduced: the time was 4000 ms, the temperature was 220°C, the pressure was 25 torr, and the flow rate of trimethylaluminum was 5000 sccm;

[0069] (7) Thermal decomposition reaction of trimethylaluminum: reaction time is 3000 ms, reaction temperature is set at 220°C, and reaction pressure is 25 Torr;

[0070] (8) Cleaning: The cleaning time is 6500 ms, the cleaning temperature is 220°C, the cleaning pressure is 25 Torr, the trimethylaluminum flow rate is 10000 sccm, the water flow rate is 10000 sccm, the temperature is kept constant, the pressure is adjusted to 30 Torr, and the gas in the furnace tube is completely extracted;

[0071] (9) Water introduction: time is set to 6000 ms, temperature is 220 °C, pressure is 25 torr, and water flow rate is 6000 sccm;

[0072] (10) Hydrothermal decomposition reaction: reaction time is 500 ms, reaction temperature is set at 220 °C, and reaction pressure is 25 torr;

[0073] (11) Cleaning: The cleaning time is 4000ms, the cleaning temperature is 220℃, the pressure is 25torr, the flow rate of trimethylaluminum is 10000sccm, the flow rate of water is 10000sccm, the temperature is kept stable, the pressure is adjusted to 30torr, and the gas in the furnace tube is completely extracted.

[0074] (12) Cyclic deposition: Steps (6) to (11) constitute one cycle, and each cycle reaction deposits 0.1 nm of aluminum oxide, and a certain number of cycles are performed;

[0075] (13) Vacuuming: time is 25 s, temperature is 250 °C, pressure is 20 torr, and excess reaction gas is evacuated;

[0076] (14) Cleaning the furnace tube: nitrogen was used to purge the residual gas in the furnace for 15 s at a temperature of 250 °C, a pressure of 20 torr, and a nitrogen flow rate of 25,000 sccm;

[0077] (15) Return to normal pressure: time 200 s, temperature 250 °C, nitrogen flow rate 50000 sccm;

[0078] (16) Boat removal: The robotic arm aluminum fixture is removed from the ALD reactor chamber. The time is 120s and the temperature is 250℃.

[0079] S2. Deposition of silicon nitride on the front side:

[0080] (1) Loading the boat: Place the silicon wafer obtained after step S1 on a graphite support fixture and send it into the tubular PECVD coating equipment by a robotic arm for 120 seconds at a temperature of 500°C and a pressure of 10,000 Pa;

[0081] (2) Vacuuming: Vacuum the furnace tube for 200 s, at a temperature of 500 °C and a pressure of 0 Pa;

[0082] (3) Leak detection: test whether the vacuum leaks, the time is 20s, the temperature is 500℃, and the pressure is 10000Pa;

[0083] (4) Vacuuming: The furnace tube was quickly evacuated again for 20 seconds at a temperature of 500°C and a pressure of 0 Pa;

[0084] (5) Pre-ventilation: adjust the pressure to 130 Pa, the flow rate of monosilane to 1380 sccm, the flow rate of nitrous oxide to 6450 sccm, the time to 20 s, and the temperature to 500 °C;

[0085] (6) Deposition of silicon oxide: deposition time 20 s, deposition temperature 500 °C, deposition pressure 240 Pa, silane flow rate 1380 sccm, nitrous oxide flow rate 6450 sccm, RF power 12600 W, pulse on / off ratio 2 / 30;

[0086] (7) Vacuuming: time is 20s, temperature is 500℃, pressure is 0Pa, and excess reaction gas is pumped away;

[0087] (8) Pre-aeration: adjust the pressure to 230 Pa, the flow rate of monosilane to 2500 sccm, the flow rate of ammonia to 7500 sccm, the time to 20 s, and the temperature to 500 °C;

[0088] (9) Silicon oxide nitridation: A certain flow rate of ammonia and a flow rate of monosilane of 2385 sccm were introduced, the time was 520 s, the temperature was 500 °C, the pressure was 240 Pa, the RF power was 14500 W, and the pulse on / off ratio was 4 / 60.

[0089] (10) Vacuuming: time is 25s, temperature is 500℃, pressure is 0Pa, and excess reaction gas is pumped away;

[0090] (11) Cleaning the furnace tube: purge the residual gas in the furnace with nitrogen for 15 s, at a temperature of 500 °C, a pressure of 0 Pa, and a nitrogen flow rate of 25,000 sccm;

[0091] (12) Return to normal pressure: time 90 s, temperature 500 °C, pressure 10000 Pa, nitrogen flow rate 50000 sccm;

[0092] (13) Boat exit: time is 110s, temperature is 500℃, pressure is set to 10000Pa, and boat exit speed is 1000mm / min.

[0093] S3. Screen printing: After the silicon nitride deposition is completed, the silicon wafer is screen-printed with metal electrodes and sintered to make solar cells.

[0094] Example 2

[0095] The difference between Example 2 and Example 1 is that the process cycles (5) to (10) in step S2 are performed twice, and the ammonia flow rates in the two cycles are 9540 sccm and 11925 sccm respectively.

[0096] Example 3

[0097] The difference between Example 3 and Example 1 is that the number of times of alternating deposition of aluminum oxide in step S1 is 60 times, and in the (10) process of step S2, the flow rate of ammonia is 8347.5 sccm, the flow rate of monosilane is 2256 sccm, the time is 520 s, the temperature is 500°C, and the pressure is 240 Pa.

[0098] Example 4

[0099] The difference between Example 4 and Example 3 is that in the process (10) of step S2, the flow rate of monosilane is 2319 sccm, the time is 550 s, the temperature is 520° C., and the pressure is 250 Pa.

[0100] Example 5

[0101] The difference between Example 5 and Example 3 is that in the process (10) of step S2, the flow rate of monosilane is 2385 sccm, the time is 570 s, the temperature is 550° C., and the pressure is 260 Pa.

[0102] Example 6

[0103] The difference between Example 6 and Example 3 is that in the process (10) of step S2, the flow rate of monosilane is 2455 sccm, the time is 580 s, the temperature is 580° C., and the pressure is 300 Pa.

[0104] The same preparation method as in Example 1 was used to prepare Examples 7-18 and Comparative Examples 1-58 with reference to the conditions provided in Table 1, and the performance of the solar cells prepared in all Examples and Comparative Examples was tested.

[0105] The performance test method is: using a light decay furnace with UV ultraviolet light, the front of the solar cell is exposed to 50kWh of ultraviolet light without any shielding, and the attenuation rate of the solar cell output power after ultraviolet irradiation is tested.

[0106] The relevant parameters and performance test results of the passivation anti-reflection films of the solar cells prepared in Examples 1-18 and Comparative Examples 1-58 are shown in Table 1 (in the test results, when the attenuation rate of the solar cell under 50Kwh ultraviolet radiation is ≥1%, it is judged as P-pass, and when the attenuation rate is <1%, it is judged as F-fail).

[0107] Table 1 Related parameters and performance test results of passivation anti-reflection film for solar cells

[0108] According to the performance test results in Table 1, under the same test conditions, after the front of the solar cells of all embodiments was exposed to unobstructed 50kWh ultraviolet irradiation, the output power attenuation rate of the solar cells was less than 1%, while after the front of the solar cells of all comparative examples was exposed to unobstructed 50kWh ultraviolet irradiation, the output power attenuation rate of the solar cells was greater than or equal to 1%. Therefore, the passivation anti-reflection film of the solar cell of the present application can improve the passivation interface loss of the solar cell caused by ultraviolet irradiation, greatly improve the light irradiation stability of the solar cell, and effectively ensure the photoelectric conversion efficiency of the solar cell.

[0109] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0110] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A solar cell comprising a passivation anti-reflection film structure, characterized in that: The passivation anti-reflection film structure includes an aluminum oxide film and at least one silicon nitride film stacked sequentially from the inside out; wherein the thickness of the aluminum oxide film is ≥5 nm, the silicon nitride film includes at least one first film, and the refractive index of the first film is ≥2.3, and the material of the first film is silicon nitride; Furthermore, when the thickness of the aluminum oxide film increases by 1 nm, the refractive index of the first film increases by 0.03 to 0.

06.

2. The solar cell according to claim 1, wherein The N / Si atomic ratio of the first film is ≤4:

1.

3. The solar cell according to claim 1 or 2, wherein When the thickness of the aluminum oxide film increases by 1 nm, the N / Si atomic ratio of the first film decreases by 0.3:1 to 0.6:

1.

4. The solar cell according to claim 1, wherein The refractive index of the silicon nitride film is ≥2.

3.

5. The solar cell according to claim 1 or 4, wherein The thickness of the aluminum oxide film is less than 13 nm; And / or, the refractive index of the silicon nitride film is ≤4.

0.

6. A method for preparing a solar cell according to any one of claims 1 to 5, characterized in that: The method for preparing the passivation anti-reflection film structure in the solar cell comprises the following steps: S1. Deposition of aluminum oxide film: Place the silicon wafer after oxidation annealing in a deposition device, introduce trimethylaluminum and water in the gas phase in sequence as one cycle of deposition, and perform X cycles of deposition, where X ≥ 50; S2. Deposit silicon nitride film: Place the silicon wafer after aluminum oxide film deposition into a deposition device, first introduce silane and nitrous oxide to deposit silicon oxide, then introduce silane and ammonia to nitride the silicon oxide, wherein the flow rate of ammonia is Ysccm, and Y=15502.5-119.25X.

7. The method for preparing a solar cell according to claim 6, wherein: In the step of introducing trimethylaluminum, the temperature is 220° C. to 300° C., the time is 7 seconds to 20 seconds, the pressure is 25 torr to 50 torr, and the flow rate of trimethylaluminum is 5000 sccm to 8000 sccm.

8. The method for preparing a solar cell according to claim 6, wherein: In the step of introducing water, the temperature is 220° C. to 300° C., the time is 6.5 seconds to 15 seconds, the pressure is 25 torr to 50 torr, and the flow rate of water is 6000 sccm to 10000 sccm.

9. The method for preparing a solar cell according to claim 6, wherein: In the step of depositing the silicon oxide film, the time is 20s to 50s, the temperature is 500°C to 600°C, the pressure is 240Pa to 500Pa, the flow rate of silane is 1380sccm to 5000sccm, and the flow rate of nitrous oxide is 6450sccm to 10000sccm.

10. The method for preparing a solar cell according to claim 6, wherein: In the step of nitriding silicon oxide, the time is 20s to 50s, the temperature is 500°C to 600°C, the pressure is 230Pa to 500Pa, the flow rate of silane is 2500sccm to 5000sccm, and the flow rate of ammonia is 7500sccm to 10000sccm.

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