Titanium seed layer and preparation method thereof and solar cell preparation method

Abstract

The present invention provides a titanium seed layer and a preparation method thereof and a solar cell preparation method, and relates to the technical field of solar cells. The titanium seed layer preparation method comprises the following steps: a titanium seed layer is prepared in a preset grid line area on a silicon substrate of a cell by a double-pulse magnetron sputtering method. Compared with the traditional method, the present invention adopts a double-pulse magnetron sputtering method to prepare a titanium seed layer, which can make the seed layer smoother and more delicate, with good dispersion, lower porosity and higher bonding strength with the substrate.

Description

Technical Field

[0001] The invention relates to the technical field of solar cells, and in particular to a titanium seed layer and a preparation method thereof, and a solar cell preparation method. Background Art

[0002] At present, photovoltaic power generation has attracted much attention, among which crystalline silicon solar cells are one of the development directions of the photovoltaic industry. Solar energy is a clean, green and renewable energy, and an effective means to achieve the goals of carbon peak and carbon neutrality, which has also led to more and more attention to solar power generation.

[0003] Metallization is one of the key processes in the preparation of silicon solar cells. It is mainly used to make silicon solar cell electrodes, forming ohmic contacts at both ends of the PN junction to achieve current output. Currently, screen printing is the most mature and common metallization process, but the silver paste used is expensive. In order to reduce the cost of solar cells and improve battery efficiency, copper electroplating technology can achieve no silver paste consumption and has the greatest cost reduction potential.

[0004] Copper electroplating refers to the electrode preparation process of depositing metallic copper on the surface of the base metal by electrolysis, and the purpose of reducing the consumption of silver paste is achieved by electroplating copper grid lines. Electroplating technology usually first plates a seed layer at the slot position of the cell, and then electroplates copper and tin as a conductive layer and a protective layer to obtain a double-sided electroplated solar cell. In the past, nickel was often used as a seed layer material, and was prepared by electroplating or chemical plating. Although chemical plating can be carried out at the same time, it is affected by the degree of activation and the effect is difficult to guarantee; electroplating is difficult to achieve double-sided simultaneous plating, resulting in a long process time, and the traditional nickel plating process usually uses the Watt nickel system or the aminosulfonic acid nickel system as the plating solution, and the Watt nickel system plating solution usually has a narrow current density range, and the electroplated nickel layer has large internal stress, high porosity, poor dispersion ability and other disadvantages. Although the nickel layer prepared by the aminosulfonic acid nickel system plating solution has small internal stress and fast deposition speed, it has poor stability and high cost.

[0005] In view of this, the present invention is proposed. Summary of the invention

[0006] One of the purposes of the present invention is to provide a method for preparing a titanium seed layer. The method for preparing a titanium seed layer comprises the following steps: preparing a titanium seed layer in a preset area of ​​a gate line on a silicon substrate of a battery by a double-pulse magnetron sputtering method. Compared with the traditional method, the present invention adopts a double-pulse magnetron sputtering method to prepare a titanium seed layer, which can make the seed layer smoother and more delicate, with good dispersion, lower porosity and higher bonding strength with the substrate.

[0007] The second object of the present invention is to provide a titanium seed layer prepared by the titanium seed layer preparation method. The titanium seed layer prepared by the present invention has a stronger bond with the substrate.

[0008] The third object of the present invention is to provide a method for preparing a solar cell. The method for preparing a solar cell comprises the following steps: preparing a mask layer on a cell substrate, removing the mask layer in a grid line preset area to form a patterned groove, preparing the titanium seed layer in the patterned groove, annealing, removing the mask layer in a non-grid line preset area, and then preparing a metal layer on the titanium seed layer to obtain a solar cell. In the solar cell prepared by this method, the bonding force between the titanium layer and the substrate is strong, so that the electrode of the solar cell is not easily separated from the substrate, thereby improving the structural stability of the solar cell.

[0009] A fourth object of the present invention is to provide a suction cup device that can effectively absorb the solar cell in the cleaning step to ensure the cleaning effect.

[0010] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted:

[0011] In a first aspect, the present invention provides a method for preparing a titanium seed layer, the method comprising the following steps:

[0012] A titanium seed layer is prepared in a preset gate line area on a silicon substrate of a battery by using a double-pulse magnetron sputtering method.

[0013] In the present invention, the dual-pulse magnetron sputtering method refers to a dual-pulse output mode containing two or more sub-pulses in one pulse cycle, which can control the pulse on and off time and current density within a single pulse width. Compared with the traditional method, the seed layer prepared by the dual-pulse magnetron sputtering method in the present invention can make the seed layer smoother and more delicate, with better dispersion, lower porosity and higher bonding strength with the substrate.

[0014] Preferably, when the titanium seed layer is prepared by double-pulse magnetron sputtering, the vacuum degree is 0.1-2Pa, for example, it can be 0.1Pa, 0.2Pa, 0.3Pa, 0.4Pa, 0.5Pa, 0.6Pa, 0.7Pa, 0.8Pa, 0.9Pa, 1Pa, 1.1Pa, 1.2Pa, 1.3Pa, 1.4Pa, 1.5Pa, 1.6Pa, 1.7Pa, 1.8Pa, 1.9Pa, 2Pa, etc., and the pulse voltage is 200-700V, for example, it can be 200V, 250V, 300V, 350V, 400V, 450V, 500V, 550V, 600V, 650V, 700V, etc., the divided pulse voltage is 10-70% of the pulse voltage, for example, it can be 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 65%, 70%, 85%, 90%, etc., the duty cycle is 10-30%, for example, it can be 10%, 15%, 20%, 25%, 30%, etc., and the average current density is 0.2-2A / cm2 , for example, it can be 0.2A / cm 2 , 0.3A / cm 2 , 0.4A / cm 2 , 0.5A / cm 2 , 0.6A / cm 2 , 0.7A / cm 2 , 0.8A / cm 2 , 0.9A / cm 2 , 1A / cm 2 , 1.1A / cm 2 , 1.2A / cm 2 , 1.3A / cm 2 , 1.4A / cm 2 , 1.5A / cm 2 , 1.6A / cm 2 , 1.7A / cm 2 , 1.8A / cm 2 , 1.9A / cm 2 , 2A / cm 2 wait;

[0015] Preferably, the thickness of the titanium seed layer is 0.1-1 μm, for example, 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, etc.

[0016] In a second aspect, the present invention provides a titanium seed layer prepared by the titanium seed layer preparation method.

[0017] In the present invention, the titanium seed layer is evenly distributed compared with the traditional nickel seed layer, and the speed of preparing the titanium seed layer is high.

[0018] In a third aspect, the present invention provides a method for preparing a solar cell, the method comprising the following steps:

[0019] A mask layer is prepared on the battery substrate, and the mask layer in the preset grid line area is removed to form a patterned groove. The titanium seed layer is prepared in the patterned groove, annealed, and the mask layer in the non-preset grid line area is removed. Then, a metal layer is prepared on the titanium seed layer to obtain a solar cell.

[0020] In the present invention, the titanium layer has a small thermal expansion coefficient, high density, and high bonding strength after heat treatment. The method of avoiding the titanium de-titanium process optimizes the solar cell metallization process to a certain extent. At the same time, the titanium layer has high conductivity, good thermal stability and corrosion resistance, good adsorption to silicon, high adhesion, and the bonding strength of the entire metal coating and the silicon substrate is greatly improved after continuing to plate the metal. The solar cell provided by the present invention is a TOPCon solar cell with a double-sided titanium seed layer. According to the equipment form, the titanium seed layer on the back of the solar cell can be prepared first, and then the titanium seed layer on the front of the solar cell can be prepared; or the titanium seed layer on the front of the solar cell can be prepared first, and then the titanium seed layer on the back of the solar cell can be prepared; or both sides can be prepared simultaneously; finally, a solar cell with a double-sided titanium seed layer is obtained. The preparation method of the present invention can also be used for the preparation of deposited grid lines containing metals such as nickel, titanium, tungsten, tantalum, cobalt, copper, and their alloys.

[0021] Preferably, the preparing the mask layer comprises: forming the mask layer on the front side and / or the back side of the solar cell substrate by deposition, coating or printing;

[0022] Preferably, a laser is used to remove the mask layer in the preset area of ​​the gate line to form a patterned groove;

[0023] In the present invention, since laser grooving generally causes damage, the mask layer can absorb part of the laser energy to reduce the damage.

[0024] Preferably, the width of the patterned groove is 5-50 μm, for example, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, etc., and the depth is 50-100 nm, for example, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, etc.;

[0025] In the present invention, the patterned grooves may include one or both of coarse grooves and fine grooves, and the number of coarse grooves and fine grooves of the patterned grooves can be adjusted; the thickness of the titanium seed layer is easy to control, and the groove width can be further optimized on this basis. At the same time, combined with the presence of the mask layer, the damage of the laser to the battery can be reduced, thereby improving the efficiency.

[0026] Preferably, the annealing temperature is 400-980°C, for example, it can be 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 980°C, etc.

[0027] Preferably, after removing the mask layer in the preset area of ​​the gate line and before preparing the titanium seed layer, the battery substrate is cleaned and dried in sequence;

[0028] Preferably, the battery substrate is cleaned with an acid cleaner;

[0029] Preferably, the pickling agent comprises an aqueous solution of hydrofluoric acid;

[0030] Preferably, the amount of hydrofluoric acid added to the pickling agent is 10-20 mL / L, for example, it can be 10 mL / L, 11 mL / L, 12 mL / L, 13 mL / L, 14 mL / L, 15 mL / L, 16 mL / L, 17 mL / L, 18 mL / L, 19 mL / L, 20 mL / L, etc.;

[0031] Preferably, the temperature of the pickling agent is 25-38°C, for example, it can be 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, etc.;

[0032] Preferably, the cleaning time is 5-50s;

[0033] In the present invention, the floating time of the silicon substrate in the pickling agent is 5-50s, for example, it can be 5s, 10s, 15s, 20s, 25s, 30s, 35s, 40s, 45s, 50s, etc.

[0034] Preferably, in the cleaning step, ultrasonic cleaning is used;

[0035] In the present invention, the cleaning step adopts wet cleaning, and whether to connect with ultrasonic waves can be selected according to the degree of cleaning.

[0036] Preferably, the drying temperature is 15-20°C, for example, it can be 15°C, 16°C, 17°C, 18°C, 19°C, 20°C, etc.

[0037] Preferably, after the battery substrate is cleaned and dried in sequence, before the titanium seed layer is prepared, the battery substrate is subjected to vacuum plasma treatment;

[0038] In the present invention, vacuum low-temperature plasma treatment can prevent silicon oxidation on the one hand, and ensure the cleaning effect on the other hand; the solar cell substrate is subjected to double pretreatment of wet cleaning and vacuum low-temperature plasma treatment, so that the solar cell substrate is thoroughly cleaned, and the bonding strength between the grid line and the substrate is effectively improved.

[0039] Preferably, when vacuum plasma treatment is adopted, the vacuum degree is 0.01-0.04 MPa, for example, it can be 0.01 MPa, 0.02 MPa, 0.03 MPa, 0.04 MPa, etc., the temperature is 15-20°C, for example, it can be 15°C, 16°C, 17°C, 18°C, 19°C, 20°C, etc., the gas used is argon or nitrogen, and the treatment time is 10-30s, for example, it can be 10s, 11s, 12s, 13s, 14s, 15s, 16s, 17s, 18s, 19s, 20s, 21s, 22s, 23s, 24s, 25s, 26s, 27s, 28s, 29s, etc.;

[0040] Preferably, preparing the metal layer comprises sequentially forming a copper plating layer and a tin plating layer on the titanium seed layer;

[0041] Preferably, the thickness of the copper plating layer is 9-12um, for example, 9um, 10um, 11um, 12um, etc.;

[0042] Preferably, the thickness of the tin-plated layer is 1-2 um, for example, 1 um, 2 um, etc.

[0043] In a fourth aspect, the present invention provides a suction cup device, comprising a suction cup body;

[0044] A first cavity is provided in the suction cup body, and the first cavity is used to communicate with a vacuum pump. A plurality of through holes are provided on the suction cup body, and the through holes are communicated with the first cavity. The suction cup body is used to adsorb the battery substrate in the cleaning step.

[0045] Preferably, the plurality of through holes are arranged in an array.

[0046] Preferably, a second cavity is formed in the suction cup body, and an airflow groove connected with the second cavity is formed along its circumference, the second cavity is used to be connected with the air outlet of the fan, and the airflow from the fan passes through the second cavity and flows out of the suction cup body through the airflow groove;

[0047] The suction cup device in the present invention is an anti-liquid flipping suction cup device. When adsorbing solar cells, its negative pressure can ensure the effective adsorption of solar cells. At the same time, air flow is released outward around the suction cup body, which can effectively prevent the liquid from flowing to the adsorption surface of the solar cell and entering the suction cup due to the movement of the suction cup or the surge of liquid during the cleaning or electroplating process, resulting in poor process effects and damage to the suction cup.

[0048] Preferably, the air flow speed released outwardly from the second cavity is 5-30m / s, for example, it can be 5m / s, 6m / s, 7m / s, 8m / s, 9m / s, 10m / s, 11m / s, 12m / s, 13m / s, 14m / s, 15m / s, 16m / s, 17m / s, 18m / s, 19m / s, 20m / s, 21m / s, 22m / s, 23m / s, 24m / s, 25m / s, 26m / s, 27m / s, 28m / s, 29m / s, 30m / s, etc.

[0049] Furthermore, the solar cell preparation method comprises the following steps:

[0050] a. Providing a solar cell substrate;

[0051] b. forming a mask layer on the front and back sides of the solar cell substrate by deposition, coating or printing;

[0052] c. removing the mask layer of the preset gate line area on the front and back sides of the solar cell silicon substrate by laser film opening, further forming a patterned groove;

[0053] d. Add an appropriate amount of hydrofluoric acid to the pure water, circulate and stir evenly to prepare an acid cleaning agent; then use a suction cup device to absorb one side of the silicon substrate of the solar cell after the film is opened, and float the other side in the acid cleaning agent. After the cleaning is completed, the solar cell is quickly blown dry in room temperature air, and the other side of the solar cell silicon substrate is turned over and cleaned according to the above method. After both sides are cleaned and dried, vacuum low-temperature plasma treatment is performed to finally obtain a double-sided acid-washed solar cell silicon substrate;

[0054] e. A titanium seed layer was prepared in the patterned grooves by double-pulse magnetron sputtering;

[0055] f. Annealing the solar cell having a double-sided titanium seed layer to form a titanium silicon alloy;

[0056] g. Cleaning to remove the front and back mask layers to obtain a solar cell having a titanium seed layer only at a preset position of the grid line;

[0057] h. Electroplating copper and tin on the surface of the solar cell silicon substrate with double-sided titanium seed layer in sequence to obtain a double-sided electroplated solar cell.

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] The titanium seed layer preparation method provided by the present invention can be used to form a titanium layer on a substrate during the preparation of a solar cell. The titanium layer prepared by the method has a strong bonding force with the substrate, making it difficult for the electrode of the solar cell to be separated from the substrate, thereby improving the structural stability of the solar cell.

[0060] The titanium seed layer provided by the present invention, when applied to a solar cell, can improve the compactness of the coating and reduce the internal stress of the coating, thereby enhancing the bonding strength between the metal coating of the entire cell and the substrate, while optimizing the related metallization process. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0062] Figure 1 A schematic structural diagram of a suction cup device provided in an embodiment of the present invention.

[0063] Icon: 1- air flow slot; 2- suction cup body; 3- through hole. DETAILED DESCRIPTION

[0064] Unless otherwise defined herein, scientific and technical terms used in conjunction with the present invention shall have the meanings commonly understood by those of ordinary skill in the art. The meaning and scope of the terms should be clear, however, in the case of any potential ambiguity, the definitions provided herein take precedence over any dictionary or external definitions. In this application, unless otherwise stated, the use of "or" means "and / or". In addition, the use of the term "including" and other forms is non-limiting.

[0065] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0066] like Figure 1 As shown, Figure 1 is a schematic diagram of the structure of the suction cup device. Figure 1 The side shown in the figure is the working surface of the suction cup device for adsorbing the battery cell.

[0067] The suction cup device provided by the present invention includes a suction cup body 2; a first cavity is opened in the suction cup body 2, the first cavity is used to connect with a vacuum pump, a plurality of through holes 3 are opened on the suction cup body 2, the through holes 3 are connected with the first cavity, and the suction cup body 2 is used to adsorb the battery substrate in the cleaning step.

[0068] Specifically, when the vacuum pump is turned on and a vacuum negative pressure is generated inside the suction cup body 2 , the surrounding atmospheric pressure will cause a relative pressure difference to form between the suction cup body 2 and the battery cell, thereby generating an adsorption force to adsorb the battery cell onto the suction cup body 2 .

[0069] In an optional embodiment, in order to improve the adsorption effect and make the adsorption strength of each point of the battery cell uniform, a plurality of through holes 3 are arranged in an array.

[0070] In an optional embodiment, a second cavity is opened in the suction cup body 2, and an airflow groove 1 connected to the second cavity is opened along its own circumference. The second cavity is used to be connected to the air outlet of the fan. The airflow from the fan passes through the second cavity and flows out of the suction cup body 2 through the airflow groove 1.

[0071] Specifically, the suction cup body 2 releases airflow outward from all sides, which can effectively prevent the liquid from flowing to the solar cell adsorption surface and entering the suction cup due to the movement of the suction cup or the surge of liquid during the cleaning or electroplating process, resulting in poor process effects and damage to the suction cup.

[0072] The working process of the suction cup device is as follows:

[0073] First, use a suction cup device to absorb one side of the solar cell silicon substrate after the film is opened, and float the other side in the pickling agent. After cleaning, quickly blow dry the solar cell in room temperature air, turn it over and clean the other side of the solar cell silicon substrate according to the above method. After both sides are cleaned and dried, vacuum low-temperature plasma treatment is performed to finally obtain a double-sided acid-washed solar cell silicon substrate.

[0074] It should be noted that the suction cup device can first absorb the front side of the silicon substrate of the solar cell after the film is opened, or it can first absorb the back side of the silicon substrate of the solar cell after the film is opened. After cleaning the first side, you can clean the other side.

[0075] The present invention first installs the air flow groove 1 with the function of preventing liquid from overflowing, which effectively prevents liquid from overflowing at the edge of the battery cell during electroplating and improves the process effect.

[0076] The present invention is further described below by way of examples. Unless otherwise specified, the materials in the examples are prepared according to existing methods or directly purchased from the market.

[0077] Example 1

[0078] This embodiment provides a method for preparing a titanium seed layer, which uses a double-pulse magnetron sputtering method to prepare a titanium seed layer in a preset gate line area on a battery silicon substrate;

[0079] When the titanium seed layer was prepared by double-pulse magnetron sputtering, the vacuum degree was 0.1 Pa, the pulse voltage was 700 V, the sub-pulse voltage was 10% of the pulse voltage, the duty cycle was 30%, and the average current density was 0.2 A / cm 2 , the thickness of the titanium seed layer is 1 μm.

[0080] Example 2

[0081] This embodiment provides a method for preparing a titanium seed layer, which uses a double-pulse magnetron sputtering method to prepare a titanium seed layer in a preset gate line area on a battery silicon substrate;

[0082] When the titanium seed layer was prepared by double-pulse magnetron sputtering, the vacuum degree was 2 Pa, the pulse voltage was 200 V, the sub-pulse voltage was 70% of the pulse voltage, the duty cycle was 10%, and the average current density was 2 A / cm 2 , the thickness of the titanium seed layer is 0.1 μm.

[0083] Example 3

[0084] This embodiment provides a method for preparing a titanium seed layer, which uses a double-pulse magnetron sputtering method to prepare a titanium seed layer in a preset gate line area on a battery silicon substrate;

[0085] When the titanium seed layer was prepared by double-pulse magnetron sputtering, the vacuum degree was 1 Pa, the pulse voltage was 450 V, the sub-pulse voltage was 40% of the pulse voltage, the duty cycle was 20%, and the average current density was 1 A / cm 2 , the thickness of the titanium seed layer is 0.5 μm.

[0086] Example 4

[0087] This embodiment provides a method for preparing a titanium seed layer. The difference from Embodiment 3 is that the thickness of the titanium seed layer is 0.05 μm.

[0088] Example 5

[0089] This embodiment provides a method for preparing a titanium seed layer. The difference from Embodiment 3 is that the thickness of the titanium seed layer is 1.1 μm.

[0090] Example 6

[0091] This embodiment provides a method for preparing a solar cell, comprising the following steps:

[0092] a. Providing a solar cell substrate;

[0093] b. forming a mask layer on the front and back sides of the solar cell substrate by deposition;

[0094] c. removing the mask layer of the preset gate line area on the front and back sides of the solar cell silicon substrate by laser film opening, and further forming a patterned groove; wherein the width of the patterned groove is 5 μm and the depth is 100 nm;

[0095] d. Add an appropriate amount of hydrofluoric acid to the pure water (wherein, the amount of hydrofluoric acid added to the pickling agent is 10 mL / L), circulate and stir evenly, and prepare the pickling agent. The temperature of the pickling agent is 38° C. and the cleaning time is 5 s; then, use a suction cup device to absorb the front side of the silicon substrate of the solar cell after the film is opened, and the back side floats in the pickling agent. After the cleaning is completed, the solar cell is quickly blown dry in room temperature air, and the front side of the solar cell silicon substrate is turned over and cleaned according to the above method. After both sides are cleaned and dried, vacuum low-temperature plasma treatment is performed, and finally a double-sided pickled solar cell silicon substrate is obtained; wherein, the drying temperature is 20° C.; when vacuum plasma treatment is used, the vacuum degree is 0.01 MPa, the temperature is 20° C., the gas used is argon, and the processing time is 10 s; the suction cup device releases the air flow velocity outward at 30 m / s;

[0096] e. A titanium seed layer is prepared in the patterned groove by the titanium seed layer preparation method provided in Example 3;

[0097] f. Annealing the solar cell having a double-sided titanium seed layer to form a titanium silicon alloy; wherein the annealing temperature is 400°C;

[0098] g. Washing in a 25% KOH solution to remove the front and back mask layers to obtain a solar cell having a titanium seed layer only at a preset position of the grid line;

[0099] h. Electroplating copper and tin on the surface of the solar cell silicon substrate with a double-sided titanium seed layer in sequence to obtain a double-sided electroplated solar cell; wherein the thickness of the copper plating layer is 12um, and the thickness of the tin plating layer is 1um.

[0100] Example 7

[0101] This embodiment provides a method for preparing a solar cell, comprising the following steps:

[0102] a. Providing a solar cell substrate;

[0103] b. forming a mask layer on the front and back sides of the solar cell substrate by printing;

[0104] c. removing the mask layer of the preset gate line area on the front and back sides of the solar cell silicon substrate by laser film opening, and further forming a patterned groove; wherein the width of the patterned groove is 50 μm and the depth is 50 nm;

[0105] d. Add an appropriate amount of hydrofluoric acid to the pure water (wherein, the amount of hydrofluoric acid added to the pickling agent is 20mL / L), circulate and stir evenly, and prepare the pickling agent. The temperature of the pickling agent is 25°C and the cleaning time is 50s; then, use a suction cup device to absorb the front side of the silicon substrate of the solar cell after the film is opened, and the back side floats in the pickling agent. After the cleaning is completed, the solar cell is quickly blown dry in room temperature air, and the front side of the solar cell silicon substrate is turned over and cleaned according to the above method. After both sides are cleaned and dried, vacuum low-temperature plasma treatment is performed, and finally a double-sided pickled solar cell silicon substrate is obtained; wherein, the drying temperature is 15°C; when vacuum plasma treatment is used, the vacuum degree is 0.04MPa, the temperature is 15°C, the gas used is nitrogen, and the processing time is 30s; the suction cup device releases the air flow velocity outward at 5m / s;

[0106] e. A titanium seed layer is prepared in the patterned groove by the titanium seed layer preparation method provided in Example 3;

[0107] f. Annealing the solar cell having a double-sided titanium seed layer to form a titanium silicon alloy; wherein the annealing temperature is 980°C;

[0108] g. Washing in a 25% KOH solution to remove the front and back mask layers to obtain a solar cell having a titanium seed layer only at a preset position of the grid line;

[0109] h. Electroplating copper and tin on the surface of the solar cell silicon substrate with a double-sided titanium seed layer in sequence to obtain a double-sided electroplated solar cell; wherein the thickness of the copper plating layer is 9um, and the thickness of the tin plating layer is 2um.

[0110] Examples 8-12

[0111] This embodiment provides a method for preparing a solar cell, comprising the following steps:

[0112] a. Providing a solar cell substrate;

[0113] b. forming a mask layer on the front and back sides of the solar cell substrate by printing;

[0114] c. removing the mask layer of the preset gate line area on the front and back sides of the solar cell silicon substrate by laser film opening, and further forming a patterned groove; wherein the width of the patterned groove is 25 μm and the depth is 75 nm;

[0115] d. Add an appropriate amount of hydrofluoric acid to the pure water (wherein, the amount of hydrofluoric acid added to the pickling agent is 15 mL / L), circulate and stir evenly, and prepare the pickling agent. The temperature of the pickling agent is 30°C and the cleaning time is 25 seconds. Then, use a suction cup device to absorb the front side of the silicon substrate of the solar cell after the film is opened, and the back side floats in the pickling agent. After the cleaning is completed, the solar cell is quickly blown dry in room temperature air, and the front side of the solar cell silicon substrate is turned over and cleaned according to the above method. After both sides are cleaned and dried, vacuum low-temperature plasma treatment is performed, and finally a double-sided pickled solar cell silicon substrate is obtained; wherein, the drying temperature is 18°C; when vacuum plasma treatment is used, the vacuum degree is 0.025MPa, the temperature is 18°C, the gas used is argon, and the processing time is 20 seconds; the suction cup device releases the air flow velocity outward at 20m / s;

[0116] e. Preparing a titanium seed layer in the patterned groove using the titanium seed layer preparation method provided in Examples 1-5;

[0117] f. Annealing a solar cell having a double-sided titanium seed layer to form a titanium silicon alloy; wherein the annealing temperature is 700°C;

[0118] g. Washing in a 25% KOH solution to remove the front and back mask layers to obtain a solar cell having a titanium seed layer only at a preset position of the grid line;

[0119] h. Electroplating copper and tin on the surface of the solar cell silicon substrate with a double-sided titanium seed layer in sequence to obtain a double-sided electroplated solar cell; wherein the thickness of the copper plating layer is 11um, and the thickness of the tin plating layer is 1.5um.

[0120] Example 13

[0121] This embodiment provides a method for preparing a solar cell. The difference from Example 10 is that in this comparative example, a titanium seed layer is prepared only in a patterned groove on the front side of the solar cell silicon substrate using the titanium seed layer preparation method provided in Example 3, and nickel electroplating is performed in the patterned groove on the back side of the solar cell silicon substrate.

[0122] The other steps are consistent with Example 10.

[0123] Embodiment 14

[0124] This embodiment provides a method for preparing a solar cell. The difference from Example 10 is that in this comparative example, a titanium seed layer is prepared only in the patterned groove on the back side of the solar cell silicon substrate using the titanium seed layer preparation method provided in Example 3, and nickel electroplating is performed in the patterned groove on the front side of the solar cell silicon substrate.

[0125] The other steps are consistent with Example 10.

[0126] Comparative Example 1

[0127] This comparative example provides a method for preparing a solar cell, which differs from Example 10 in that steps g and h are swapped, that is, copper and tin are electroplated first, and then the mask layer in the non-gridline preset area is removed.

[0128] Test Case

[0129] Test samples: TOPCon solar cells prepared in Examples 6-12 and TOPCon solar cells prepared in Comparative Example 1 were used.

[0130] Test methods: (1) Electrical performance test: offline solar IV tester;

[0131] (2) Welding tension under low temperature conditions: tensile gauge.

[0132] The test results are shown in Table 1.

[0133] Table 1

[0134]

[0135]

[0136] It can be seen from the data in Table 1 that the solar cell with a double-sided titanium seed layer provided by the embodiment of the present invention has a strong bonding force between the titanium layer and the substrate and a higher conversion efficiency of the cell; and, a titanium seed layer that is too thin or too thick will affect the bonding force between the titanium layer and the substrate and the efficiency of the cell; at the same time, compared to Comparative Example 1, the embodiment of the present invention removes the mask layer first and then plates other metals, thereby avoiding the reaction of the mask layer with other plating solutions and affecting the performance of the cell.

[0137] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a solar cell, characterized in that: The solar cell preparation method comprises the following steps: A mask layer is prepared on a battery substrate, and the mask layer in a preset grid line area is removed to form a patterned groove. A titanium seed layer is prepared in the patterned groove, and annealed to remove the mask layer in a non-preset grid line area, and then a metal layer is prepared on the titanium seed layer to obtain a solar cell; Wherein, the titanium seed layer preparation method comprises the following steps: A titanium seed layer is prepared in a preset gate line area on a silicon substrate of a battery by using a double-pulse magnetron sputtering method; When the titanium seed layer is prepared by double-pulse magnetron sputtering, the vacuum degree is 0.1-2 Pa, the pulse voltage is 200-700 V, the sub-pulse voltage is 10-70% of the pulse voltage, the duty cycle is 10-30%, and the average current density is 0.2-2 A / cm 2 .

2. The method for preparing a solar cell according to claim 1, characterized in that: The thickness of the titanium seed layer is 0.1-1 μm.

3. The method for preparing a solar cell according to claim 1, characterized in that: The preparation of the mask layer comprises: forming the mask layer on the front side and / or the back side of the solar cell substrate by deposition, coating or printing.

4. The method for preparing a solar cell according to claim 1, characterized in that: The mask layer in the preset area of ​​the gate line is removed by laser.

5. The method for preparing a solar cell according to claim 1, characterized in that: The width of the patterned groove is 5-50 μm and the depth is 50-100 nm.

6. The method for preparing a solar cell according to claim 1, characterized in that: The annealing temperature is 400-980°C.

7. The method for preparing a solar cell according to claim 1, characterized in that: After removing the mask layer in the preset area of ​​the gate line and before preparing the titanium seed layer, the battery substrate is cleaned and dried in sequence.

8. The method for preparing a solar cell according to claim 7, characterized in that: The battery substrate is cleaned with an acid cleaner.

9. The method for preparing a solar cell according to claim 8, characterized in that: The pickling agent includes an aqueous solution of hydrofluoric acid.

10. The method for preparing a solar cell according to claim 9, characterized in that: The amount of hydrofluoric acid added to the pickling agent is 10-20 mL / L.

11. The method for preparing a solar cell according to claim 8, characterized in that: The temperature of the pickling agent is 25-38°C.

12. The method for preparing a solar cell according to claim 7, characterized in that: The cleaning time is 5-50 s.

13. The method for preparing a solar cell according to claim 7, characterized in that: In the cleaning step, ultrasonic cleaning is adopted.

14. The method for preparing a solar cell according to claim 7, characterized in that: The drying temperature is 15-20℃.

15. The method for preparing a solar cell according to claim 7, characterized in that: After the battery substrate is cleaned and dried in sequence, the battery substrate is subjected to vacuum plasma treatment before the titanium seed layer is prepared.

16. The method for preparing a solar cell according to claim 15, characterized in that: When vacuum plasma treatment is used, the vacuum degree is 0.01-0.04 MPa, the temperature is 15-20°C, the gas used is argon or nitrogen, and the treatment time is 10-30s.

17. The method for preparing a solar cell according to claim 1, characterized in that: The preparation of the metal layer includes sequentially forming a copper plating layer and a tin plating layer on the titanium seed layer.

18. The method for preparing a solar cell according to claim 17, characterized in that: The thickness of the copper plating layer is 9-12 um.

19. The method for preparing a solar cell according to claim 17, characterized in that: The thickness of the tin-plated layer is 1-2 um.

20. The method for preparing a solar cell according to claim 7, characterized in that In the cleaning step, a suction cup device is used to absorb the battery substrate.

21. The method for preparing a solar cell according to claim 20, characterized in that: The suction cup device comprises a suction cup body (2); a first cavity is provided in the suction cup body (2), the first cavity is used to communicate with a vacuum pump, a plurality of through holes (3) are provided on the suction cup body (2), the through holes (3) are communicated with the first cavity, and the suction cup body (2) is used to adsorb the battery substrate in the cleaning step.

22. The method for preparing a solar cell according to claim 21, characterized in that: The plurality of through holes (3) are arranged in an array.

23. The method for preparing a solar cell according to claim 22, characterized in that: A second cavity is provided in the suction cup body (2), and an airflow groove (1) connected to the second cavity is provided along its circumference. The second cavity is used to be connected to an air outlet of a fan. The airflow from the fan passes through the second cavity and flows out of the suction cup body (2) through the airflow groove (1).

24. The method for preparing a solar cell according to claim 23, characterized in that: The air flow velocity released outward from the second cavity is 5-30 m / s.

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