A method for manufacturing a photovoltaic cell

Abstract

The application relates to a preparation method of a photovoltaic cell, which comprises the following steps: a film plating process, in which a nitrogen source is pre-ionized in a film plating device, then a silicon source is introduced, film plating is carried out, so that a passivation layer and / or an anti-reflection layer is formed on the cell; a laser doping injection process, in which the cell after the film plating is subjected to laser doping injection; and a UV irradiation process, in which the cell after the laser doping injection is subjected to screen printing and sintering treatment, then is subjected to UV irradiation treatment, so that the photovoltaic cell is obtained. According to the method, after the screen printing and the sintering treatment, the ultraviolet lamp irradiation treatment is added; the short-wave light of the ultraviolet light makes the free hydrogen ions generated in the film plating stage react with the passivation substances on the silicon surface again, so that the passivation level is improved.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic cell technology, and in particular to a method for preparing photovoltaic cells. Background Technology

[0002] A photovoltaic (PV) cell is a device that converts light energy into electrical energy using the photovoltaic effect. One method for fabricating a PV cell includes steps such as texturing, pre-boron diffusion, laser scanning, post-boron diffusion, alkaline back etching, growth of a tunneling oxide layer and an intrinsic amorphous silicon layer, phosphorus doping, cleaning (removal of the silicon coating), passivation, film deposition, screen printing, and sintering. Currently, in the cell production process, the back-side PECVD stage uses ammonia gas to ionize the film, filling the space beneath the film with free hydrogen, which then reacts with the surface silicon layer to achieve passivation.

[0003] CN111384209B discloses a method for reducing pollution and improving conversion efficiency of ALD PERC cells, including the following steps: (1) placing the cell coated with aluminum oxide film into a furnace tube for depositing front anti-reflective film; (2) heating the furnace tube, evacuating the gas, filling with nitrogen, and adjusting the pressure inside the furnace tube; (3) completing the ionization of gas to form plasma; (4) completing the deposition of multilayer anti-reflective film; (5) completing the deposition of front anti-reflective film on the cell.

[0004] CN117613144A discloses a photovoltaic cell and its fabrication method, including providing a silicon wafer with a boron-doped layer formed on its first side; sequentially growing an aluminum oxide layer and an anti-reflection layer on the first side of the silicon wafer to obtain a silicon wafer with an anti-reflection layer as the outermost layer on the first side; polishing the second side of the silicon wafer with an anti-reflection layer as the outermost layer on the first side to obtain a polished silicon wafer; and sequentially growing a tunneling oxide layer, a polycrystalline silicon layer, and an anti-reflection layer on the second side of the polished silicon wafer to obtain a photovoltaic cell with an anti-reflection layer as the outermost layer on the second side.

[0005] CN120769597A discloses a method for preparing a photovoltaic cell, comprising providing a photovoltaic cell intermediate, the photovoltaic cell intermediate including a silicon substrate and an aluminum oxide layer located on at least one surface of the silicon substrate; performing plasma nitriding treatment on the aluminum oxide layer using process gases including silane and ammonia to transform the aluminum oxide layer into an aluminum oxynitride layer, and forming a silicon nitride layer on the surface of the aluminum oxynitride layer away from the silicon substrate.

[0006] However, the reaction of free hydrogen generated in the PECVD stage of the above process is incomplete. The resulting solar cell still has unreacted free hydrogen on the back side film, while the front side lacks it, leading to poor passivation performance. Therefore, a new method for preparing photovoltaic cells is urgently needed to improve passivation. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a method for preparing photovoltaic cells. The method of this invention involves adding UV irradiation treatment after screen printing and sintering. The short-wavelength effect of ultraviolet light utilizes the effect of ultraviolet light to cause free hydrogen ions generated during the coating stage to re-react with the passivation material on the silicon surface, thereby improving the passivation level.

[0008] To achieve this objective, the present invention adopts the following technical solution: This invention provides a method for preparing photovoltaic cells, the method comprising: In the coating process, a nitrogen source is placed in a coating device for pre-ionization, and then a silicon source is introduced to perform coating, so that the solar cell forms a passivation layer and / or an anti-reflection layer. The laser doping and implantation process involves laser doping and implantation into the coated solar cells. The UV irradiation process involves screen printing and sintering the laser-doped solar cell, followed by UV irradiation to obtain the photovoltaic solar cell.

[0009] This invention involves introducing ammonia gas before PECVD coating on the front side for pre-ionization. Utilizing the characteristics of non-equilibrium plasma, radio frequency glow discharge causes intense thermal motion between ammonia (NH3) and SiH4 molecules under high-frequency action, leading to molecular ionization through collisions and the formation of silicon nitride (SiN). x By adding UV irradiation treatment after screen printing and sintering, the short-wavelength light effect of ultraviolet light is used to make the free hydrogen ions generated in the coating stage react with the passivation material on the silicon surface to improve the passivation level.

[0010] As a preferred embodiment of the present invention, the nitrogen source includes ammonia.

[0011] Preferably, the ammonia flow rate is 8000-9000 L / min, such as 8000 L / min, 8200 L / min, 8400 L / min, 8600 L / min, 8800 L / min, 9000 L / min, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0012] Preferably, the ammonia gas is introduced for 10-15 seconds, for example, 10 seconds, 11 seconds, 12 seconds, 13 seconds, 14 seconds, or 15 seconds.

[0013] As a preferred technical solution of the present invention, the pre-ionization radio frequency power is 10-12kW, such as 10kW, 10.5kW, 11kW, 11.5kW, 12kW, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0014] Preferably, the pre-ionization time is 40-60s, such as 40s, 45s, 50s, 55s, 60s, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0015] In this invention, increasing the pre-ionization time results in an equal increase in the gas flow rate. During the coating process, ionization occurs in an environment with excess free hydrogen, generating a large amount of SiN. x The Si-H bonds in the hydrogenated amorphous silicon passivation layer are broken by ultraviolet photons, releasing hydrogen atoms and ions. Under the influence of ultraviolet light and temperature gradient (the residual temperature of the drying oven after printing), free hydrogen diffuses from the interior of the passivation layer to the C-Si surface, filling lattice defects (such as vacancies and dangling crystal bonds) and forming a stable Si-H passivation structure.

[0016] As a preferred embodiment of the present invention, the silicon source includes silane.

[0017] As a preferred technical solution of the present invention, the coating includes coating the front side of the battery cell and / or coating the back side of the battery cell.

[0018] Preferably, the back of the battery cell is subjected to ammonia ionization treatment before coating; Preferably, the ionization time of the pre-ammonia ionization treatment is 90-120s, such as 90s, 95s, 100s, 105s, 110s, 115s, 120s, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0019] In this invention, extending the ionization time of the back-side PECVD helps to improve the passivation effect of the solar cell, ultimately improving the conversion efficiency of the photovoltaic cell.

[0020] Preferably, the ammonia flow rate for the pre-ammonia ionization treatment is 9000-10000 L / min, such as 9000 L / min, 9200 L / min, 9400 L / min, 9600 L / min, 9800 L / min, 10000 L / min, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0021] Preferably, the radio frequency power of the pre-ammonia ionization treatment is 12-15kW, such as 12kW, 12.5kW, 13kW, 13.5kW, 14kW, 14.5kW, 15kW, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0022] As a preferred embodiment of the present invention, the UV irradiation treatment includes irradiating the front side of the battery cell with an ultraviolet lamp.

[0023] As a preferred technical solution of the present invention, the vertical distance between the ultraviolet lamp and the front of the battery cell is 5-10cm, such as 5cm, 6cm, 7cm, 8cm, 9cm, 10cm, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0024] As a preferred technical solution of the present invention, the power of the UV irradiation treatment is 300-360W, such as 300W, 310W, 320W, 330W, 340W, 350W, 360W, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0025] As a preferred technical solution of the present invention, the irradiation time of the UV irradiation treatment is 2-3s, such as 2s, 2.2s, 2.4s, 2.6s, 2.8s, 3s, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0026] As a preferred technical solution of the present invention, the method includes: In the coating process, a nitrogen source is placed in a coating device for pre-ionization, and then a silicon source is introduced to perform coating, so that the solar cell forms a passivation layer and / or an anti-reflection layer. The nitrogen source includes ammonia; the flow rate of the ammonia is 8000-9000 L / min; the ammonia introduction time is 10-15 s; the pre-ionization radio frequency power is 10-12 kW; the pre-ionization time is 40-60 s; the silicon source includes silane. The coating process includes coating the front side of the battery cell and / or coating the back side of the battery cell; the back side of the battery cell is pre-treated with ammonia gas ionization before coating; the ionization time of the pre-treatment is 90-120s; the ammonia flow rate of the pre-treatment is 9000-10000L / min; and the radio frequency power of the pre-treatment is 12-15kW. The laser doping and implantation process involves laser doping and implantation into the coated solar cells. The UV irradiation process involves screen printing and sintering the laser-doped solar cell, followed by UV irradiation to obtain the photovoltaic solar cell. The UV irradiation process includes irradiating the front of the solar cell with an ultraviolet lamp. The vertical distance between the ultraviolet lamp and the front of the solar cell is 5-10 cm. The power of the UV irradiation process is 300-360 W. The irradiation time is 2-3 seconds.

[0027] Compared with the prior art, the present invention has at least the following beneficial effects: This invention involves introducing ammonia gas before PECVD coating on the front side for pre-ionization. Utilizing the characteristics of non-equilibrium plasma, radio frequency glow discharge causes intense thermal motion between ammonia (NH3) and SiH4 molecules under high-frequency action, leading to molecular ionization through collisions and the formation of silicon nitride (SiN). x By adding UV irradiation treatment after screen printing and sintering, the short-wavelength light effect of ultraviolet light is used to make the free hydrogen ions generated in the coating stage react with the passivation material on the silicon surface to improve the passivation level. Attached Figure Description

[0028] Figure 1 This is a comparison chart of the cell efficiency of the photovoltaic cells prepared in Example 1 and Comparative Example 2 of this invention.

[0029] Figure 2 This is a cell efficiency diagram of the photovoltaic cells prepared in Examples 1, 2 and Comparative Example 2 of this invention. Detailed Implementation

[0030] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0031] Example 1 This embodiment provides a method for preparing a photovoltaic cell, the method comprising: In the coating process, ammonia gas is placed in a coating device for pre-ionization, followed by the introduction of silane for coating, so that the battery cell forms a passivation layer and an anti-reflection layer; the flow rate of the ammonia gas is 9000 L / min, and the introduction time is 15 s; the radio frequency power of the pre-ionization is 10 kW, and the time is 60 s; The coating includes coating the front side of the battery cell and coating the back side of the battery cell; the back side of the battery cell is pre-treated with ammonia gas ionization before coating; the ionization time of the pre-treatment with ammonia gas ionization is 120s, the ammonia gas flow rate is 9000L / min, and the radio frequency power is 12kW. The laser doping and implantation process involves laser doping and implantation into the coated solar cells. The UV irradiation process involves screen printing and sintering the laser-doped solar cell, followed by UV irradiation to obtain the photovoltaic solar cell. The UV irradiation process includes irradiating the front of the solar cell with an ultraviolet lamp. The vertical distance between the ultraviolet lamp and the front of the solar cell is 5 cm. The power of the UV irradiation process is 360 W, and the irradiation time is 2 seconds.

[0032] Example 2 This embodiment provides a method for preparing a photovoltaic cell, the method comprising: In the coating process, ammonia gas is placed in a coating device for pre-ionization, and then silane is introduced for coating to form a passivation layer and an anti-reflection layer on the battery cell; the flow rate of the ammonia gas is 8000 L / min and the introduction time is 10 s; the radio frequency power of the pre-ionization is 12 kW and the time is 40 s. The coating process includes coating the front side of the battery cell and coating the back side of the battery cell; the back side of the battery cell is pre-treated with ammonia gas ionization before coating; the ionization time of the pre-treatment with ammonia gas ionization is 90s, the ammonia gas flow rate is 10000L / min, and the radio frequency power is 15kW. The laser doping and implantation process involves laser doping and implantation into the coated solar cells. The UV irradiation process involves screen printing and sintering the laser-doped solar cell, followed by UV irradiation to obtain the photovoltaic solar cell. The UV irradiation process includes irradiating the front of the solar cell with an ultraviolet lamp. The vertical distance between the ultraviolet lamp and the front of the solar cell is 10 cm. The power of the UV irradiation process is 300 W, and the irradiation time is 2.5 s.

[0033] Example 3 This embodiment provides a method for preparing a photovoltaic cell, the method comprising: In the coating process, ammonia gas is placed in a coating device for pre-ionization, and then silane is introduced for coating to form a passivation layer and an anti-reflection layer on the battery cell; the flow rate of the ammonia gas is 8500 L / min, and the introduction time is 12 s; the radio frequency power of the pre-ionization is 11 kW, and the time is 50 s. The coating process includes coating the front side of the battery cell and coating the back side of the battery cell; the back side of the battery cell is pre-treated with ammonia gas ionization before coating; the ionization time of the pre-treatment with ammonia gas ionization is 100s, the ammonia gas flow rate is 9500L / min, and the radio frequency power is 13kW. The laser doping and implantation process involves laser doping and implantation into the coated solar cells. The UV irradiation process involves screen printing and sintering the laser-doped solar cell, followed by UV irradiation to obtain the photovoltaic solar cell. The UV irradiation process includes irradiating the front of the solar cell with an ultraviolet lamp. The vertical distance between the ultraviolet lamp and the front of the solar cell is 8 cm. The power of the UV irradiation process is 330 W, and the irradiation time is 3 s.

[0034] Example 4 This embodiment provides a method for preparing a photovoltaic cell. The only difference from Embodiment 1 is that the ionization time of the back-side PECVD is 60s, while all other aspects are the same as in Embodiment 1.

[0035] Example 5 This embodiment provides a method for preparing a photovoltaic cell, which differs from Embodiment 1 only in that the back of the cell is pre-ionized with ammonia gas before coating; the ionization time of the pre-ionization with ammonia gas is 150s, and all other aspects are the same as in Embodiment 1.

[0036] Comparative Example 1 This comparative example provides a method for preparing a photovoltaic cell. The only difference from Example 1 is that pre-ionization is not performed; instead, ammonia gas and silane are directly introduced together for coating to form a passivation layer and an anti-reflection layer on the cell. All other aspects are the same as in Example 1.

[0037] Comparative Example 2 This comparative example provides a method for preparing a photovoltaic cell, which differs from Example 1 only in that UV irradiation treatment is not performed; all other aspects are the same as in Example 1.

[0038] The cell efficiency of the photovoltaic cells obtained in Examples 1-5 and Comparative Examples 1-2 was tested, and the test results are shown in Table 1.

[0039] Table 1 The test results show that: (1) As can be seen from Examples 1 to 3, the method of the present invention can effectively improve the cell efficiency of photovoltaic cells, up to 26.545%.

[0040] (2) As can be seen from Examples 1 and 4-5, the present invention can improve the efficiency of photovoltaic cells by extending the ionization time of the pre-ammonia ionization treatment. However, further extending the ionization time will reduce the efficiency of photovoltaic cells.

[0041] (3) As can be seen from Example 1 and Comparative Example 1, the present invention pre-ionizes ammonia and then introduces silane to deposit a silicon nitride antireflection coating; while in Comparative Example 1, ammonia and silane are introduced together, which can also ionize and deposit a silicon nitride antireflection coating, but there will be unreacted free hydrogen, which affects the passivation effect of the cell and ultimately reduces the cell efficiency of the photovoltaic cell.

[0042] (4) As can be seen from Example 1 and Comparative Example 2, the photovoltaic cell in Comparative Example 2, which did not undergo UV irradiation treatment, has a lower cell efficiency than the photovoltaic cell in Example 1; Figure 1 It can be clearly seen that the photovoltaic cell efficiency in Example 1 is 0.02%-0.03% higher than that in Comparative Example 2; from Figure 2As can be seen, the cell efficiency of the photovoltaic cells in Examples 1 and 2 is higher than that in Comparative Example 2, and the cell efficiency of the photovoltaic cells in Example 2 is 0.09%-0.1% higher than that in Comparative Example 2.

[0043] In summary, this invention provides a method for preparing photovoltaic cells. Before PECVD coating on the front side, ammonia gas is introduced for pre-ionization. Utilizing the characteristics of non-equilibrium plasma, radio frequency glow discharge causes intense thermal motion between ammonia (NH3) and SiH4 molecules under high-frequency action, leading to molecular ionization through collisions and the formation of silicon nitride (SiN). x By adding ultraviolet light irradiation after screen printing and sintering, the short-wavelength light effect of ultraviolet light is used to make the free hydrogen ions generated in the coating stage react with the passivation material on the silicon surface to improve the passivation level.

[0044] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a photovoltaic cell, characterized in that, The preparation method includes: In the coating process, a nitrogen source is placed in a coating device for pre-ionization, and then a silicon source is introduced to perform coating, so that the solar cell forms a passivation layer and / or an anti-reflection layer. The laser doping and implantation process involves laser doping and implantation into the coated solar cells. The UV irradiation process involves screen printing and sintering the laser-doped solar cell, followed by UV irradiation to obtain the photovoltaic solar cell.

2. The preparation method according to claim 1, characterized in that, The nitrogen source includes ammonia; Preferably, the flow rate of the ammonia gas is 8000-9000 L / min; Preferably, the ammonia gas is introduced for 10-15 seconds.

3. The preparation method according to claim 1 or 2, characterized in that, The pre-ionization radio frequency power is 10-12kW; the pre-ionization time is 40-60s.

4. The preparation method according to any one of claims 1-3, characterized in that, The silicon source includes silane.

5. The preparation method according to any one of claims 1-4, characterized in that, The coating includes coating the front side of the battery cell and / or coating the back side of the battery cell; Preferably, the back of the battery cell is subjected to ammonia ionization treatment before coating; Preferably, the ionization time of the pre-ammonia ionization treatment is 90-120 s; Preferably, the ammonia flow rate for the pre-ammonia ionization treatment is 9000-10000 L / min; Preferably, the radio frequency power of the pre-ammonia ionization treatment is 12-15kW.

6. The preparation method according to any one of claims 1-5, characterized in that, The UV irradiation treatment includes irradiating the front of the battery cells with ultraviolet lamps.

7. The preparation method according to any one of claims 1-6, characterized in that, The vertical distance between the ultraviolet lamp and the front of the battery cell is 5-10cm.

8. The preparation method according to any one of claims 1-7, characterized in that, The power of the UV irradiation treatment is 300-360W.

9. The preparation method according to any one of claims 1-8, characterized in that, The UV irradiation treatment lasts for 2-3 seconds.

10. The preparation method according to any one of claims 1-9, characterized in that, The preparation method includes: In the coating process, a nitrogen source is placed in a coating device for pre-ionization, and then a silicon source is introduced to perform coating, so that the solar cell forms a passivation layer and / or an anti-reflection layer. The nitrogen source includes ammonia; the flow rate of the ammonia is 8000-9000 L / min; the ammonia introduction time is 10-15 s; the pre-ionization radio frequency power is 10-12 kW; the pre-ionization time is 40-60 s; the silicon source includes silane. The coating process includes coating the front side of the battery cell and / or coating the back side of the battery cell; the back side of the battery cell is pre-treated with ammonia gas ionization before coating; the ionization time of the pre-treatment is 90-120s; the ammonia flow rate of the pre-treatment is 9000-10000L / min; and the radio frequency power of the pre-treatment is 12-15kW. The laser doping and implantation process involves laser doping and implantation into the coated solar cells. The UV irradiation process involves screen printing and sintering the laser-doped solar cell, followed by UV irradiation to obtain the photovoltaic solar cell. The UV irradiation process includes irradiating the front of the solar cell with an ultraviolet lamp. The vertical distance between the ultraviolet lamp and the front of the solar cell is 5-10 cm. The power of the UV irradiation process is 300-360 W. The irradiation time is 2-3 seconds.

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