Selective emitter and method of making the same, solar cell, and electric device

Abstract

The application discloses a selective emitter, a preparation method thereof, a solar cell and a power utilization device. The preparation method of the selective emitter comprises the following steps: providing a prefabricated structure, the prefabricated structure comprising a substrate and a first doped layer opposite to the conduction type of the substrate formed on one side of the substrate; sequentially forming a second doped layer and a third doped layer on the first doped layer, the conduction types of the second doped layer, the third doped layer and the first doped layer being the same; and performing laser processing on a surface of the third doped layer in a preset electrode area. Through the prefabricated structure of the formed pn junction, a low-flux slow deposition process and a high-flux fast deposition process are sequentially superimposed on the first doped layer, a dense high-doped-concentration second doped layer is first deposited, and then a third doped layer with a lower doped concentration is deposited, and subsequent laser processing does not damage the surface while further improving the emitter uniformity, effectively improving the emitter doping stability and the cell efficiency stability.

Description

Technical Field

[0001] This invention relates to the field of solar cells, and in particular to a selective emitter and its preparation method, a solar cell, and an electrical device. Background Technology

[0002] Solar photovoltaic (PV) power generation is a technology that directly converts sunlight into electricity using the photovoltaic effect. Solar energy is inexhaustible and not limited by geographical location, making it considered the most competitive clean energy source. With increasing energy demand, the market demand for more efficient and affordable PV power plants is constantly growing. Improving the power generation efficiency of PV power plants and reducing production and operating costs has become a key focus for the contemporary PV industry.

[0003] Selective emitter (SE) solar cells involve high-concentration doping at and near the contact area between the metal grid lines and the silicon wafer, while low-concentration doping occurs in areas outside the electrodes. This reduces the contact resistance between the silicon wafer and the electrodes, decreases surface recombination, and improves minority carrier lifetime, resulting in a significant improvement in cell conversion efficiency. In traditional emitter-back-passivated (PERC) monocrystalline silicon cells, the diffusion sheet resistance is maintained at around 175±5Ω during diffusion processes. While high impurity concentrations can be achieved during the deposition of phosphosilicate glass (PSG) in the fabrication of selective emitters, it is impossible to simultaneously achieve a uniformly low sheet resistance emitter. This leads to poor emitter contact, preventing the full potential of the SE structure from being realized, hindering the achievement of maximum efficiency gains, and preventing the cell from exhibiting a normal efficiency distribution with a small standard deviation and consistent performance. Summary of the Invention

[0004] Therefore, in order to solve the problem of poor emitter uniformity in large-size batteries, improve emitter doping stability and battery efficiency stability, it is necessary to provide a selective emitter and its preparation method, a solar cell, and an electrical device.

[0005] This application provides a method for preparing a selective emitter, comprising the following steps:

[0006] A prefabricated structure is provided, the prefabricated structure comprising: a substrate and a first doped layer formed on one side of the substrate with a conductivity type opposite to that of the substrate, the first doped layer having a first doping concentration;

[0007] A second doped layer with a second doping concentration and a third doped layer with a third doping concentration are sequentially formed on the first doped layer. The first doped layer, the second doped layer and the third doped layer have the same conductivity type, and the third doping concentration is less than the second doping concentration.

[0008] The surface of the third doped layer is subjected to laser processing of the preset electrode area;

[0009] The conditions for preparing the second doped layer include: the flow rate of the first nitrogen gas containing the dopant source is 600 sccm to 1400 sccm, the flow rate of the first oxygen gas is 200 sccm to 800 sccm, and the preparation time is 400 s to 600 s.

[0010] The conditions for preparing the third doped layer include: a second nitrogen gas flow rate of 2000 sccm to 3000 sccm containing the dopant source, a second oxygen gas flow rate of 800 sccm to 1500 sccm, and a preparation time of 200 s to 400 s.

[0011] In one embodiment, the materials of the second doped layer and the third doped layer include phosphosilicate glass or borosilicate glass.

[0012] In one embodiment, the substrate is of P-type conductivity, the materials of the second doped layer and the third doped layer include phosphosilicate glass, and the doping source is phosphorus oxychloride.

[0013] In one embodiment, the substrate is of N-type conductivity, the materials of the second doped layer and the third doped layer include borosilicate glass, and the doping source is boron tribromide or boron trichloride.

[0014] In one embodiment, the conditions for preparing the second doped layer and the conditions for preparing the third doped layer each independently include: a preparation temperature of 750°C to 800°C and a preparation time of 250s to 600s.

[0015] In one embodiment, the conditions for the laser processing include: a laser wavelength of 514nm to 543nm and a laser power of 25W to 45W.

[0016] In one embodiment, an oxidation process is further included after the formation of the third doped layer.

[0017] In one embodiment, the conditions for the oxidation treatment include an oxidation temperature of 710°C to 760°C.

[0018] In one embodiment, the sheet resistance of the preset electrode region after the laser treatment is 72 Ω / cm. 2 ~81Ω / cm 2 .

[0019] Furthermore, this application also provides a selective emitter prepared according to the above-described preparation method.

[0020] Furthermore, this application provides a solar cell including the selective emitter as described above.

[0021] This application also provides an electrical device, including a solar cell as described above as a power source.

[0022] By prefabricating the already formed pn junction, a dense, highly doped second doped layer is first deposited on the first doped layer through a combination of low-throughput slow deposition and high-throughput fast deposition processes. Then, a third doped layer with a lower doped concentration is deposited, which improves the uniformity of the doped layer deposition. This ensures that the subsequent laser processing will not damage the surface, while also further improving the emitter uniformity, effectively improving the emitter doping stability and the battery efficiency stability. Attached Figure Description

[0023] Figure 1 The solar cell structures were prepared by the method of preparing selective emitters according to Examples 1 to 3 and Comparative Examples 1 to 3 in sequence;

[0024] Explanation of reference numerals in the attached figures: 10: Solar cell; 100: Substrate; 110: Selective emitter; 120: First silicon nitride layer; 130: Alumina layer; 140: Second silicon nitride layer; 150: First electrode; 160: Second electrode. Detailed Implementation

[0025] This application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application. Of course, they are merely examples and are not intended to limit this application. Furthermore, reference numerals and / or letters may be repeated in different instances. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate a relationship between the various embodiments and / or settings discussed.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of the application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0027] Unless otherwise specified, all percentages, fractions, and ratios are calculated based on the total mass of the compositions of this application. Unless otherwise specified, all masses of the listed ingredients are given as the content of the active substance and therefore do not include solvents or byproducts that may be present in commercially available materials. The term "percentage by mass" may be expressed by the symbol "%".

[0028] The terms “comprising,” “including,” “containing,” “having,” “comprising,” or other variations thereof are intended to cover non-closed inclusion, and no distinction is made between these terms. The term “comprising” means additional steps and components that may be added without affecting the final result. The term “comprising” also includes the terms “composed of” and “substantially composed of.” The compositions and methods / processes of this application comprise, consist of, and substantially consist of the essential elements and limitations described herein, as well as any additional or optional ingredients, components, steps, or limitations described herein. No distinction is made between the terms “efficacy,” “performance,” “effect,” and “potency” herein.

[0029] The terms "preferred," "more preferably," etc., used in this application refer to embodiments of this application that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this application.

[0030] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0031] This application provides a method for preparing a selective emitter, comprising the following steps:

[0032] A prefabricated structure is provided, comprising: a substrate and a first doped layer formed on one side of the substrate with a conductivity type opposite to that of the substrate, the first doped layer having a first doping concentration;

[0033] A second doped layer with a second doping concentration and a third doped layer with a third doping concentration are sequentially formed on the first doped layer. The first doped layer, the second doped layer and the third doped layer have the same conductivity type, and the third doping concentration is less than the second doping concentration.

[0034] Laser processing is performed on the surface of the pre-defined electrode region of the third doped layer;

[0035] The conditions for preparing the second doped layer include: the flow rate of the first nitrogen gas containing the dopant source is 600 sccm to 1400 sccm, the flow rate of the first oxygen gas is 200 sccm to 800 sccm, and the preparation time is 400 s to 600 s.

[0036] The conditions for preparing the third doped layer include: a second nitrogen gas flow rate of 2000 sccm to 3000 sccm containing the dopant source, a second oxygen gas flow rate of 800 sccm to 1500 sccm, and a preparation time of 200 s to 400 s.

[0037] By prefabricating the already formed pn junction, a dense, highly doped second doped layer is first deposited on the first doped layer through a combination of low-throughput slow deposition and high-throughput fast deposition processes. Then, a third doped layer with a lower doped concentration is deposited. This ensures that subsequent laser processing will not damage the surface while further improving the emitter uniformity, effectively enhancing the emitter doping stability and battery efficiency stability.

[0038] Understandably, the laser treatment is followed by an alkaline polishing etching process to remove the plating that occurred during the formation of the first, second, and third doped layers.

[0039] Furthermore, the conditions for preparing the second doped layer include: a first nitrogen gas flow rate of 700 sccm to 1300 sccm containing the dopant source, and a first oxygen gas flow rate of 250 sccm to 750 sccm.

[0040] Preferably, the conditions for preparing the second doped layer include: the flow rate of the first nitrogen gas containing the dopant source is 800 sccm to 1200 sccm, and the flow rate of the first oxygen gas is 300 sccm to 700 sccm. Specifically, the flow rate of the first nitrogen gas containing the dopant source can be, but is not limited to, 800 sccm, 900 sccm, 1000 sccm, 1100 sccm, or 1200 sccm. Preferably, the flow rate of the first nitrogen gas containing the dopant source is 800 sccm to 1200 sccm, and the flow rate of the first oxygen gas can be, but is not limited to, 300 sccm, 400 sccm, 500 sccm, 600 sccm, or 700 sccm.

[0041] Furthermore, the conditions for preparing the third doped layer include: a second nitrogen gas flow rate of 2000 sccm to 2800 sccm containing the dopant source, and a second oxygen gas flow rate of 700 sccm to 1500 sccm.

[0042] Preferably, the conditions for preparing the third doped layer include: the flow rate of the second nitrogen gas containing the dopant source is 2200 sccm to 2600 sccm, and the flow rate of the second oxygen gas is 900 sccm to 1300 sccm. Specifically, the flow rate of the second nitrogen gas containing the dopant source can be, but is not limited to, 2200 sccm, 2300 sccm, 2400 sccm, 2500 sccm, or 2600 sccm, and the flow rate of the second oxygen gas can be, but is not limited to, 900 sccm, 1000 sccm, 1100 sccm, 1200 sccm, or 1300 sccm.

[0043] In a specific example, the materials of the second doped layer and the third doped layer include phosphosilicate glass or borosilicate glass.

[0044] In one specific example, the substrate is of P-type conductivity, and the materials of the second and third doped layers include phosphosilicate glass, with phosphorus oxychloride as the doping source.

[0045] In a specific example, the substrate is of N-type conductivity, and the materials of the second and third doped layers include borosilicate glass, with the doping source being boron tribromide or boron trichloride.

[0046] In a specific example, the conditions for preparing the second doped layer and the conditions for preparing the third doped layer each independently include: a preparation temperature of 750℃~800℃ and a preparation time of 250s~600s.

[0047] Understandably, the conditions for preparing the second doped layer include: a preparation temperature of 750℃ to 800℃ and a preparation time of 400s to 600s. Further, the preparation temperature of the second doped layer may be, but is not limited to, 750℃, 760℃, 770℃, 780℃, 790℃ or 800℃, and the preparation time of the second doped layer may be, but is not limited to, 400s, 420s, 440s, 460s, 480s, 500s, 520s, 540s, 560s, 580s or 600s.

[0048] Furthermore, the conditions for preparing the third doped layer include: a preparation temperature of 750℃~800℃ and a preparation time of 250s~350s. Furthermore, the temperature for preparing the second doped layer may be, but is not limited to, 750℃, 760℃, 770℃, 780℃, 790℃ or 800℃, and the preparation time may be, but is not limited to, 250s, 260s, 270s, 280s, 290s, 300s, 310s, 320s, 330s, 340s or 350s.

[0049] In a specific example, the conditions for preparing the second doped layer and the conditions for preparing the third doped layer each independently include a pressure of 50 Pa to 80 Pa; specifically, the pressure may be, but is not limited to, 50 Pa, 55 Pa, 60 Pa, 65 Pa, 70 Pa, 75 Pa or 80 Pa.

[0050] In a specific example, the laser processing conditions include: a laser wavelength of 514nm to 543nm and a laser power of 25W to 45W.

[0051] The laser wavelength can be, but is not limited to, 514nm, 519nm, 524nm, 529nm, 530nm, 531nm, 532nm, 533nm, 538nm, or 543nm. Specifically, the conditions for laser processing can include, but are not limited to, pulsed lasers using a single wavelength of 532nm and laser power between 30W and 40W. Further, the power of laser processing can be, but is not limited to, 30W, 32W, 34W, 36W, 38W, or 40W.

[0052] In one specific example, an oxidation process is included after the formation of the third doped layer.

[0053] In a specific example, the oxidation treatment conditions include: an oxidation temperature of 710℃~760℃; further, the oxidation treatment conditions also include an oxidation treatment pressure of 80Pa~120Pa, a third oxygen flow rate of 2000sccm~2800sccm, and a third nitrogen flow rate of 300sccm~800sccm.

[0054] Furthermore, the oxidation treatment conditions include: an oxidation temperature of 720℃~750℃, an oxidation treatment pressure of 90Pa~110Pa, a third oxygen flow rate of 2300sccm~2700sccm, and a third nitrogen flow rate of 400sccm~600sccm.

[0055] Specifically, the oxidation temperature in the oxidation treatment conditions can be, but is not limited to, 720℃, 730℃, 740℃ or 750℃; the oxidation pressure can be, but is not limited to, 90Pa, 95Pa, 100Pa, 105Pa or 110Pa; the third oxygen flow rate can be, but is not limited to, 2300sccm, 2400sccm, 2500sccm, 2600sccm or 2700sccm; and the third nitrogen flow rate can be, but is not limited to, 400sccm, 450sccm, 500sccm, 550sccm or 600sccm.

[0056] This application optimizes the fabrication process of subsequent doped layers in the main pn junction formed by the first doped layer and the substrate, thereby optimizing the fabrication time without increasing the amount of doping source used and without increasing additional fabrication costs.

[0057] In a specific example, the method for forming the first doped layer in the prefabricated structure may include, but is not limited to, the steps of initial oxidation, pre-deposition, first high-temperature propulsion, oxidation propulsion, second high-temperature propulsion, and cooling.

[0058] Understandably, taking phosphorus as the dopant source as an example, the "small nitrogen" refers to nitrogen carrying the phosphorus source (phosphorus oxychloride). Specifically, pure nitrogen is passed into the liquid phosphorus source bottle, and the phosphorus source carries the liquid phosphorus source, forming the "small nitrogen." The "large nitrogen" refers to the nitrogen that maintains the pressure inside the tube and cleans the furnace tube, and also carries away heat from the furnace during cooling. The "small oxygen" reacts with phosphorus oxychloride to prevent phosphorus oxychloride from decomposing into phosphorus trichloride under anaerobic conditions.

[0059] Furthermore, the conditions for the initial oxidation include a nitrogen flow rate of 80 sccm–120 sccm, an oxygen flow rate of 1100 sccm–1700 sccm, a pressure of 50 Pa–170 Pa, a time of 120 s–450 s, and a temperature of 750 °C–800 °C. Even further, the initial oxidation comprises two stages: the first stage includes a nitrogen flow rate of 80 sccm–120 sccm, an oxygen flow rate of 1100 sccm–1700 sccm, a pressure of 120 Pa–170 Pa, and a time of 200 s–300 s; the second stage includes a nitrogen flow rate of 80 sccm–120 sccm, an oxygen flow rate of 1100 sccm–1500 sccm, a pressure of 50 Pa–80 Pa, and a time of 100 s–200 s.

[0060] In a specific example, the pre-deposition conditions include a nitrogen flow rate of 400 sccm–1200 sccm, an oxygen flow rate of 400 sccm–1200 sccm, a pressure of 50 Pa–80 Pa, a time of 100 s–650 s, and a temperature of 750 °C–800 °C. Further, the pre-deposition includes three stages. The first stage includes a nitrogen flow rate of 700 sccm–1200 sccm, an oxygen flow rate of 400 sccm–700 sccm, a pressure of 50 Pa–80 Pa, and a time of 200 s–300 s. The first stage has a temperature of 750℃~800℃. The second stage includes a flow rate of small nitrogen gas of 400sccm~600sccm and a flow rate of small oxygen gas of 700sccm~1200sccm, a pressure of 50Pa~80Pa, a time of 100s~150s, and a temperature of 750℃~800℃. The third stage includes a flow rate of small nitrogen gas of 700sccm~1200sccm and a flow rate of small oxygen gas of 400sccm~700sccm, a pressure of 50Pa~80Pa, a time of 150s~250s, and a temperature of 750℃~800℃.

[0061] In a specific example, the conditions for the first high-temperature propulsion included a flow rate of 800 sccm to 1200 sccm for the large nitrogen gas, a flow rate of 700 sccm to 1200 sccm for the small nitrogen gas, a pressure of 50 Pa to 80 Pa, a time of 200 s to 400 s, and a temperature of 800 °C to 900 °C.

[0062] In a specific example, the conditions for oxidation propulsion include a flow rate of 100 sccm to 500 sccm for the large nitrogen gas, a flow rate of 300 sccm to 800 sccm for the small nitrogen gas, a flow rate of 800 sccm to 1200 sccm for the small oxygen gas, a pressure of 50 Pa to 80 Pa, a time of 200 s to 400 s, and a temperature of 800 °C to 900 °C.

[0063] In a specific example, the conditions for the second high-temperature propulsion included a flow rate of 800 sccm to 1200 sccm for the large nitrogen gas, a flow rate of 600 sccm to 1200 sccm for the small nitrogen gas, a pressure of 50 Pa to 80 Pa, a time of 300 s to 500 s, and a temperature of 800 °C to 900 °C.

[0064] In a specific example, the cooling conditions include a nitrogen flow rate of 800 sccm–1200 sccm, a nitrogen flow rate of 500 sccm–1000 sccm, a oxygen flow rate of 1500 sccm–2000 sccm, a pressure of 50 Pa–80 Pa, a time of 100 s–900 s, and a temperature of 700 °C–900 °C. Further, the cooling process includes three stages. The first stage includes a nitrogen flow rate of 800 sccm–1200 sccm, a nitrogen flow rate of 500 sccm–1000 sccm, a pressure of 50 Pa–80 Pa, a time of 500 s–800 s, and a temperature of 700 °C–900 °C. The first stage has a temperature of 750℃~900℃. The second stage includes a flow rate of 800sccm~1200sccm for large nitrogen and 500sccm~1000sccm for small nitrogen, with a pressure of 50Pa~80Pa, a time of 550s~750s, and a temperature of 750℃~850℃. The third stage includes a flow rate of 800sccm~1200sccm for large nitrogen, 600sccm~1000sccm for small nitrogen and 1500sccm~2000sccm for small oxygen, with a pressure of 50Pa~80Pa, a time of 100s~250s, and a temperature of 750℃~850℃.

[0065] In a specific example, the sheet resistance of the preset electrode area after laser treatment is 72 Ω / cm. 2 ~81Ω / cm 2 .

[0066] Specifically, the sheet resistance of the preset electrode area after laser treatment can be, but is not limited to, 72 Ω / cm. 2 73Ω / cm 2 74Ω / cm 2 75Ω / cm 2 76Ω / cm 2 77Ω / cm 2 78Ω / cm 2 79Ω / cm 2 80Ω / cm 2 Or 81Ω / cm 2 Preferably, the sheet resistance of the preset electrode area after laser treatment is 72 Ω / cm. 2 ~78Ω / cm 2 .

[0067] Furthermore, this application also provides a selective emitter prepared according to the above-described preparation method.

[0068] Furthermore, this application provides a solar cell including the selective emitter as described above.

[0069] Understandably, the aforementioned solar cells may be, but are not limited to, emitter passivated and back-contact cells (PERC cells).

[0070] Furthermore, this application provides an electrical device that includes the aforementioned solar cell as a power source. It is understood that the aforementioned electrical device may include, but is not limited to, transformers, reactors, capacitors, combined electrical appliances, circuit breakers, instrument transformers, surge arresters, coupling capacitors, transmission lines, power cables, grounding devices, generators, synchronous condensers, motors, enclosed busbars, and thyristors.

[0071] The selective emitter and its preparation method, as well as the solar cell of this application, are further described in detail below with reference to specific embodiments. Unless otherwise specified, all raw materials used in the following embodiments are commercially available products.

[0072] Provide a kind of Figure 1 The solar cell 10 shown has a structure including a substrate 100, a selective emitter 110 formed on one side of the substrate 100, a first silicon nitride layer 120 formed on the selective emitter 110, an aluminum oxide layer 130 and a second silicon nitride layer 140 formed on the other side of the substrate 100, a first electrode 150 in contact with the selective emitter 110 formed on the surface of the first silicon nitride 120, and a second electrode 160 in contact with the aluminum oxide layer 130 formed on the surface of the second silicon nitride 140. The selective emitter 110 is prepared according to the methods for preparing selective emitters in the following embodiments and comparative examples.

[0073] Example 1

[0074] This embodiment provides a method for preparing a selective emitter, including the following steps:

[0075] A prefabricated structure is provided, the prefabricated structure including a substrate and a first doped layer formed on one side of the substrate with a conductivity type opposite to that of the substrate;

[0076] The fabrication process and parameters of the first doped layer are shown in Table 1 below:

[0077] Table 1: Preparation Parameters of Example 1

[0078]

[0079] A second doped layer and a third doped layer are then formed sequentially on the first doped layer.

[0080] The subsequent oxidation treatment was carried out under the following conditions: 730℃~740℃, 100Pa, in an atmosphere of 500sccm nitrogen and 2500sccm oxygen for 210s.

[0081] The surface of the third doped layer is subjected to laser processing on a preset electrode region. The laser processing parameters include: laser wavelength of 532nm and laser power of 33W.

[0082] The experimental parameters for different preparations of selective emitters in Examples 1-3 and Comparative Examples 1-3 are summarized in Table 2 below:

[0083] Table 2: Preparation parameters for Examples 1-3 and Comparative Examples 1-3

[0084]

[0085] The sheet resistance values ​​before and after selective emitter laser treatment obtained through the above embodiments and comparative examples are summarized in Table 3 below:

[0086] Table 3: Sheet resistance values ​​of selective emitter lasers before and after treatment obtained in each embodiment and comparative example.

[0087]

[0088] The selective emitters prepared according to each embodiment and each comparative example are fabricated as follows: Figure 1 The electrical performance parameters of the solar cells with the following structure are summarized in Table 4 below:

[0089] Table 4: Electrical performance parameters of solar cells fabricated with selective emitters in each embodiment and comparative example

[0090] Isc(A) Uoc(V) FF (%) Rs(ohm) Rsh(ohm) Standard deviation of battery efficiency distribution Example 1 18.223 0.6912 82.67 0.00074 560.2 0.1294 Example 2 18.225 0.6916 82.68 0.00075 685.9 0.0932 Example 3 18.222 0.6913 82.61 0.00085 351.1 0.1373 Comparative Example 1 18.219 0.6915 82.44 0.00088 674.9 0.1411

[0091] It is evident that the selective emitter prepared according to this application has good uniformity, effectively improving the emitter doping stability. The solar cells containing the selective emitters of Examples 1-3 have higher efficiency and stability than the solar cells containing the comparative selective emitters.

[0092] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0093] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above 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.

[0094] The above embodiments are merely illustrative of several implementation methods of this application, designed to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. A method for preparing a selective emitter, characterized in that, Includes the following steps: A prefabricated structure is provided, the prefabricated structure comprising: a substrate and a first doped layer formed on one side of the substrate with a conductivity type opposite to that of the substrate, the first doped layer having a first doping concentration; A second doped layer with a second doping concentration and a third doped layer with a third doping concentration are sequentially formed on the first doped layer. The first doped layer, the second doped layer and the third doped layer have the same conductivity type, and the third doping concentration is less than the second doping concentration. The surface of the third doped layer is subjected to laser treatment on a predetermined electrode region. After laser treatment, the sheet resistance of the predetermined electrode region is 72 Ω / cm. 2 ~81Ω / cm 2 ; The conditions for preparing the second doped layer include: a first nitrogen gas flow rate of 600 sccm to 1400 sccm containing the dopant source, a first oxygen gas flow rate of 200 sccm to 800 sccm, and a preparation time of 400 s to 600 s. The conditions for preparing the third doped layer include: a second nitrogen gas flow rate of 2000 sccm to 3000 sccm containing the dopant source, a second oxygen gas flow rate of 800 sccm to 1500 sccm, and a preparation time of 200 s to 400 s.

2. The method for preparing a selective emitter as described in claim 1, characterized in that, The materials of the second doped layer and the third doped layer include phosphosilicate glass or borosilicate glass.

3. The method for preparing a selective emitter as described in claim 2, characterized in that, The substrate is of P-type conductivity, the materials of the second doped layer and the third doped layer include phosphosilicate glass, and the doping source is phosphorus oxychloride.

4. The method for preparing a selective emitter as described in claim 2, characterized in that, The substrate is of N-type conductivity, the materials of the second doped layer and the third doped layer include borosilicate glass, and the doping source is boron tribromide or boron trichloride.

5. The method for preparing a selective emitter as described in claim 1, characterized in that, The conditions for preparing the second doped layer and the conditions for preparing the third doped layer each independently include: a preparation temperature of 750℃~800℃ and a preparation time of 250s~600s.

6. The method for preparing a selective emitter as described in claim 1, characterized in that, The conditions for laser processing include: laser wavelength of 514nm~543nm and laser power of 25W~45W.

7. The method for preparing a selective emitter as described in claim 1, characterized in that, The process includes an oxidation step after the formation of the third doped layer.

8. The method for preparing a selective emitter as described in claim 7, characterized in that, The oxidation treatment conditions include an oxidation temperature of 710℃~760℃.

9. A selective emitter, characterized in that, Prepared according to the preparation method according to any one of claims 1 to 8.

10. A solar cell, characterized in that, Includes the selective emitter as described in claim 9.

11. An electrical appliance, characterized in that, The solar cell described in claim 10 is used as a power source.

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