Solar cell and preparation method thereof

Abstract

The invention provides a solar cell and a preparation method thereof, and relates to the field of solar cells, and the preparation method of the solar cell comprises the steps: obtaining a silicon material, carrying out the first deposition processing of the silicon material to form a passivation contact layer, obtaining a phosphorus source, carrying out the phosphorus diffusion on the passivation contact layer, and carrying out the second deposition processing of the silicon material to form a passivation contact layer; sequentially forming a first mask layer, a second mask layer and a third mask layer on the passivation contact layer to obtain a boron source, performing boron diffusion on the first contact surface, performing selective emitter laser doping on the first contact surface, performing second deposition treatment on the silicon material, and performing second deposition treatment on the silicon material to obtain a second contact surface; the first contact surface and the second contact surface of the silicon material are made to form aluminum oxide layers, doping of the silicon material is increased through boron diffusion, the passivation effect of the cell is improved, emitter contact resistance and emitter region dark saturation current are reduced through selective emitter laser doping, and the conversion efficiency of the cell is improved.

Description

Technical Field

[0001] This invention relates to the field of solar cells, and more particularly to a solar cell and a method for its fabrication. Background Technology

[0002] Interdigitated back contact (IBC) batteries have their PN junction and metal contacts located on the back side of the battery, without the influence of metal electrodes blocking the front side. Therefore, they have higher short-circuit current. At the same time, the back side can allow for wider metal grid lines to reduce series resistance, thereby improving the fill factor.

[0003] In related technologies, IBC cells retain the original silicon wafer doping only through back laser grooving, resulting in poor doping and passivation effects, which affects the photoelectric conversion efficiency of the cell. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, this application provides a solar cell and a method for its fabrication.

[0005] In a first aspect, this application provides a method for fabricating a solar cell, comprising: obtaining silicon material and performing a first deposition treatment on the silicon material to form a passivation contact layer of a predetermined thickness on a first contact surface of the silicon material; obtaining a phosphorus source and performing phosphorus diffusion on the passivation contact layer, and then sequentially forming a first mask layer, a second mask layer, and a third mask layer on the passivation contact layer; obtaining a boron source and performing boron diffusion on the first contact surface, and then selectively doping the first contact surface with an emitter laser to perform high-concentration doping in the electrode region and low-concentration light doping in the light absorption region; and performing a second deposition treatment on the silicon material to form an aluminum oxide layer on both the first and second contact surfaces of the silicon material.

[0006] In conjunction with the first aspect, in one possible implementation, before performing boron diffusion on the first contact surface, the first contact surface needs to be slotted to form P+ doped regions and N+ doped regions arranged in an interdigitated pattern on the first contact surface, and the first contact has a positive gate line and a negative gate line, the positive gate line being connected to the P+ doped region, and the negative gate line being connected to the N+ doped region.

[0007] In conjunction with the first aspect, in one possible implementation, the method for fabricating the solar cell further includes a step of screen printing the silicon material to print silver-aluminum paste in the P+ doped region.

[0008] In conjunction with the first aspect, in one possible implementation, the passivation contact layer includes: a silicon oxide layer and a doped silicon layer, the silicon oxide layer having a first preset thickness and being located on the first contact surface, the doped silicon layer having a second preset thickness greater than the first preset thickness, and the doped silicon layer being located on the side of the silicon oxide layer away from the first contact surface.

[0009] In conjunction with the first aspect, in one possible implementation, the boron source is BCl3, and after boron diffusion occurs on the first contact surface, a borosilicate glass layer is formed on the first contact surface, wherein the borosilicate glass layer is a doping source for selective emitter laser doping.

[0010] In conjunction with the first aspect, in one possible implementation, the phosphorus source is POCl3, and the first mask layer is a silicon oxide layer, the second mask layer is a silicon nitride layer, and the third mask layer is silicon oxide.

[0011] In conjunction with the first aspect, in one possible implementation, the second contact surface needs to be subjected to thermal oxidation treatment before the first contact surface is subjected to boron diffusion, so as to form a fourth mask layer on the second contact surface, wherein the fourth mask layer is silicon oxide.

[0012] In conjunction with the first aspect, in one possible implementation, the silicon material has a first preset sheet resistance after phosphorus diffusion, and the first contact surface needs to be oxidized and degraded during the second deposition process of the silicon material so that the silicon material after the oxidation and degradation process has a second preset sheet resistance, wherein the first preset sheet resistance is 40 Ω / sq and the second preset sheet resistance is 65 Ω / sq.

[0013] In conjunction with the first aspect, in one possible implementation, the method for fabricating the solar cell further includes the step of fabricating a perovskite stack on the second contact surface, wherein the perovskite stack comprises a first conductive layer, a hole transport layer, a perovskite layer, a first electron transport layer, a second electron transport layer, and a second conductive layer sequentially stacked on the second contact surface.

[0014] Secondly, this application provides a solar cell prepared using the solar cell preparation method described above.

[0015] Compared with the prior art, the beneficial effects of this application are:

[0016] The method for fabricating a solar cell provided in this application involves depositing a passivation contact layer onto a silicon material, and then sequentially forming a first mask layer, a second mask layer, and a third mask layer on the passivation contact layer to achieve multiple mask layers. The silicon material is subjected to boron diffusion and selective emitter laser doping. On the one hand, boron diffusion increases the doping of the silicon material, improving the passivation effect of the cell. On the other hand, selective emitter laser doping involves high-concentration doping in the electrode region and low-concentration light doping in the light absorption region. This allows for the formation of a lateral n+ / n high-low junction at the boundary between the lightly doped and highly doped regions, and an n+ / p junction below the electrode grid line. This reduces the emitter contact resistance and the dark saturation current in the emitter region, and increases the fill factor, short-circuit current, and open-circuit voltage, thereby improving the cell's conversion efficiency. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 A schematic diagram of the process for fabricating a solar cell is shown. Detailed Implementation

[0019] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0020] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0021] 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 one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0022] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0023] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0024] Example 1

[0025] Please see Figure 1 This application provides a method for preparing a solar cell, which includes the following steps:

[0026] S100: Obtain silicon material and perform a first deposition process on the silicon material to form a passivation contact layer of a predetermined thickness on the first contact surface of the silicon material;

[0027] S200: Obtain a phosphorus source, and after phosphorus diffusion on the passivation contact layer, sequentially form a first mask layer, a second mask layer, and a third mask layer on the passivation contact layer.

[0028] S300: Obtain a boron source, and after performing boron diffusion on the first contact surface, selectively emitter laser doping is performed on the first contact surface to perform high-concentration doping in the electrode region and low-concentration light doping in the light absorption region.

[0029] S400: Perform a second deposition process on the silicon material to form aluminum oxide on both the first contact surface and the second contact surface of the silicon material;

[0030] S500: A first conductive layer is deposited on the second contact surface, and a hole transport layer, a perovskite layer, a first electron transport layer, a second electron transport layer and a second conductive layer are sequentially formed on the first conductive layer.

[0031] In some embodiments, the silicon material in S100 includes a first contact surface and a second contact surface disposed opposite to each other. The first contact surface is the back side of the silicon material. The second contact surface is the front side of the silicon material.

[0032] In some embodiments, the silicon material in S100 is an N-type silicon wafer with dimensions of 182mm*183.75mm and a sheet resistance greater than 300Ω / sq.

[0033] In some embodiments, the silicon material in S100 needs to undergo alkaline polishing during the first deposition process to form a polished surface with high reflectivity, thereby improving the flatness of the battery surface and increasing the reflection of long-wavelength light to promote secondary absorption of light.

[0034] In some embodiments, the specific process of the alkaline polishing treatment is as follows: the silicon wafer is placed in an alkaline solvent at 65°C for 280s for double-sided polishing to form 8μm to 10μm cubes on the first contact surface and the second contact surface, and the alkaline solvent includes the following components: 30L concentrated KOH, 6L alkaline polishing additive and 440L pure water.

[0035] In some embodiments, the passivation contact layer in S100 includes a silicon oxide layer and a doped silicon layer. The silicon oxide layer has a first preset thickness. The silicon oxide layer is located on the first contact surface. The doped silicon layer has a second preset thickness, which is greater than the first preset thickness. The doped silicon layer is located on the side of the silicon oxide layer away from the first contact surface. The composite layer of the silicon oxide layer and the doped silicon layer together forms a passivation contact structure, which can effectively reduce surface recombination and metal contact recombination of the battery.

[0036] In some embodiments, the first preset thickness is 2nm to 3nm. The second preset thickness is 110nm to 130nm.

[0037] In some embodiments, the silicon material in S100 undergoes a first deposition process of low-pressure chemical vapor deposition, and the first deposition process includes preparing the silicon oxide layer and preparing the doped silicon layer.

[0038] In some embodiments, the specific process for preparing the silicon oxide layer is as follows: placing the silicon material in a reactor, introducing 20,000 sccm of oxygen into the reactor, and adjusting the temperature and pressure of the reactor to make the temperature of the reactor 605°C and the pressure 860 N, maintaining this for 6.5 min, so as to form the silicon oxide layer on the first contact surface.

[0039] In some embodiments, the specific process for preparing the doped silicon layer is as follows: after the silicon oxide layer on the first contact surface is prepared, 210 sccm of silane is introduced into the reactor, and the temperature and pressure of the reactor are adjusted so that the temperature of the reactor is 598°C and the pressure is 50 N, and maintained for 31 min, so as to form the doped silicon layer on the silicon oxide layer.

[0040] In some embodiments, the phosphorus source is POCl3, and the specific process of phosphorus diffusion in S200 is as follows: the silicon material after the first deposition treatment is completed is placed in a diffusion furnace, and POCl3, O2 and N2 are introduced into the diffusion furnace, with the flow rate of POCl3 being 130 sccm / min, the flow rate of O2 being 700 sccm / min and the flow rate of N2 being 1800 sccm / min. The temperature of the diffusion furnace is adjusted to 920°C and the pressure is 170 mbar, and maintained for 12 min. Then the silicon material is heated to 980°C and treated for 55 min under the conditions of a pressure of 920 mbar and an O2 flow rate of 12000 sccm / min to form an N+ doped region.

[0041] In some embodiments, the silicon material has a first preset sheet resistance after phosphorus diffusion. Sheet resistance tests are performed on the silicon material before and after phosphorus diffusion using a sheet resistance meter. The sheet resistance of the silicon material before phosphorus diffusion is found to be 300 Ω / sq, and the first preset sheet resistance is 40 Ω / sq. After phosphorus diffusion treatment, the sheet resistance of the silicon material is reduced, thus lowering its resistivity.

[0042] In some embodiments, the first mask layer is a silicon oxide layer, and the first mask layer is formed on the first contact surface by subjecting the silicon material to a first thermal oxidation treatment, thereby serving as a mask.

[0043] In some embodiments, the specific process of the first thermal oxidation treatment is as follows: take out the silicon material after phosphorus diffusion, place the silicon material in an oxidation annealing furnace, introduce 2000 sccm of O2 into the oxidation annealing furnace, adjust the temperature of the oxidation annealing furnace to 450°C, and maintain it for 15 minutes to deposit silicon oxide on the first contact surface.

[0044] In some embodiments, the second mask layer is a silicon nitride layer, and the second mask layer is formed on the first contact surface by performing a first coating process on the silicon material to serve as a mask.

[0045] In some embodiments, the specific process of the first coating treatment is as follows: take out the silicon material after the first thermal oxidation treatment, place the silicon material in a plasma-enhanced chemical vapor deposition equipment, adjust the temperature of the equipment to 500°C, the pressure to 1500Pa, and introduce 1400sccm of silane, 400sccm of ammonia and 1000sccm of nitrogen dioxide into the equipment, maintain for 6 minutes, so as to deposit the silicon nitride layer.

[0046] In some embodiments, the third mask layer is silicon oxide, and the third mask layer is formed on the first contact surface by performing a second thermal oxidation treatment on the silicon material to serve as a mask. The specific process of the second thermal oxidation treatment is the same as that of the first thermal oxidation treatment.

[0047] In some embodiments, before performing boron diffusion on the first contact surface, the first contact surface needs to be slotted to form P+ doped regions and N+ doped regions arranged in an interdigitated pattern on the first contact surface, and the first contact has a positive gate line and a negative gate line, the positive gate line being connected to the P+ doped region and the negative gate line being connected to the N+ doped region.

[0048] In some embodiments, the specific process of the grooving process is as follows: a grooving is performed on the first contact surface by laser marking with a laser. The laser marking speed is 35000mm / s, the laser power is 30w, the frequency is 1200Hz, the grooving depth is 1.2μm, and the width is 350μm, so as to destroy the doped silicon layer of the P+ doped region and expose the N-type original silicon wafer.

[0049] In some embodiments, the silicon material after laser grooving needs to be acid-washed and texturized to create a textured surface on the second contact surface, thereby increasing the light absorption rate.

[0050] In some embodiments, the pickling is carried out in 1.5% HCl by mass. The texturing process is performed at 65°C for 520 seconds, and the texturing reagent comprises the following components: 20L concentrated KOH, 6L additive, and 440L water.

[0051] In some embodiments, before the first contact surface is subjected to boron diffusion, the second contact surface needs to undergo a third thermal oxidation treatment to form a fourth mask layer on the second contact surface, which serves as a mask. The fourth mask layer is silicon oxide, and the process of the third thermal oxidation treatment is the same as that of the second thermal oxidation treatment.

[0052] In some embodiments, after the second contact surface undergoes a third thermal oxidative treatment, the first contact surface needs to undergo a second deposition treatment, and the process of the second deposition treatment is the same as that of the first deposition treatment.

[0053] In some embodiments, the boron source in S300 is BCl3, and the specific process of boron diffusion is as follows: the silicon material after the third thermal oxidation treatment is taken out, and the silicon material is placed in a diffusion furnace. 320 sccm of BCl3, 800 sccm of O2 and 3300 sccm of N2 are introduced into the diffusion furnace. The temperature of the diffusion furnace is adjusted to 935°C and maintained for 580 s to form a P+ layer, which increases the doping of the P+ doped region and improves the passivation effect of the battery.

[0054] In some embodiments, the specific process of selective emitter laser doping in S300 is as follows: the silicon material after the boron diffusion treatment is taken out, and a laser pulse is emitted through a laser emitter to melt the surface of the silicon wafer, wherein the power of the laser emitter is 42W and the picosecond speed emitted by the laser emitter is 32000mm / min.

[0055] In some embodiments, after the silicon material in S300 undergoes the boron diffusion treatment, a boron-rich borosilicate glass layer is formed on the first contact surface. The laser emitter uses this boron-rich borosilicate glass layer as a dopant source, emitting a high-frequency laser pulse to melt the surface of the silicon material. This causes boron atoms in the borosilicate glass layer to propagate to the surface of the silicon material. After solidification, the doped boron atoms rapidly replace the positions of silicon atoms, thereby achieving the purpose of dopant atom diffusion. The sheet resistance of the silicon material after selective emitter laser doping is 150 Ω / sq.

[0056] In some embodiments, the selective emitter laser doping involves high-concentration doping in the electrode region and low-concentration light doping in the light absorption region. This allows for the formation of a lateral n+ / n high-low junction at the boundary between the lightly doped and highly doped regions, and an n+ / p junction below the electrode gate. This structure can reduce the emitter contact resistance and the dark saturation current in the emitter region, and improve the fill factor, short-circuit current, and open-circuit voltage, thereby increasing the cell's conversion efficiency.

[0057] In some embodiments, the first contact surface needs to be oxidized and degraded during the second deposition process of the silicon material so that the silicon material after the oxidation and degradation process has a second preset sheet resistance, which is 65Ω / sq.

[0058] In some embodiments, the specific process of the oxidation degradation treatment is as follows: the silicon material is placed in an oxidation annealing furnace, O2 at 3000 sccm is introduced into the oxidation annealing furnace, the temperature of the oxidation annealing furnace is adjusted to 450°C, and maintained for 12 minutes. The oxidation degradation treatment, through high temperature, allows the diffused boron to redistribute and form an oxide layer, which plays a protective role during alkaline polishing.

[0059] In some embodiments, before performing the second deposition process on the silicon material in S400, a cleaning process is required to remove silicon oxide from the first contact surface. The specific cleaning process is as follows: the silicon material after oxidation degradation treatment is placed sequentially in a first mixed acid solution, a mixed alkaline solution at 65°C, and a second mixed acid solution. The first mixed acid solution includes the following components: HCl with a mass concentration of 1.5% and HF with a mass concentration of 1.5%. The mixed alkaline solution includes the following components: 15L concentrated KOH, 6L additives, and 420L pure water. The silicon material is cleaned in the mixed alkaline solution for 280 seconds. The components of the second mixed acid solution are the same as those of the first mixed acid solution.

[0060] In some embodiments, the specific process of the second deposition process in S400 is as follows: the cleaned silicon material is placed in an atomic layer deposition furnace, 19000 sccm of O2 and 19000 sccm of TMA are introduced into the atomic layer deposition furnace, and the temperature of the atomic layer deposition furnace is adjusted to 300°C. The deposition is carried out 12 times to deposit alumina on the first contact surface and the second contact surface to improve the passivation effect.

[0061] In some embodiments, the silicon material after the second deposition process needs to undergo a second coating process to further improve the passivation effect of the battery. The specific process of the second coating process is the same as that of the first coating process.

[0062] In some embodiments, the silicon material after the second coating treatment needs to undergo screen printing to print silver paste on the main gate, silver-aluminum paste on the laser-grooved P+ doped region, and silver paste on the non-laser-grooved N+ doped region. The silver paste printed by laser grooving can etch silicon nitride, eliminating the need for laser drilling and reducing damage to the passivation layer.

[0063] In some embodiments, the silicon material after the screen printing process needs to be sintered at 758°C to obtain a T-IBC cell for 5 seconds, so that the metal grid lines and the diffusion layer of the cell can form good contact, thereby enabling the current collection function.

[0064] In some embodiments, the method for fabricating the solar cell further includes the step of fabricating a perovskite stack on the second contact surface, wherein the perovskite stack comprises a first conductive layer, a hole transport layer, a perovskite layer, a first electron transport layer, a second electron transport layer, and a second conductive layer that are sequentially stacked on the second contact surface.

[0065] In some embodiments, the specific process for preparing the perovskite stack is as follows: The sintered T-IBC battery is placed in a magnetron sputtering apparatus to deposit a 220 nm thick indium oxide layer as the first conductive layer. The radio frequency of the magnetron sputtering apparatus is 12.6 MHz. Then, a 50 nm thick NiO and PVK layer is prepared on the indium oxide layer by vacuum deposition of copper oxide to form the hole transport layer. NiO acts as an electron receiver layer, and PVK is a polymer material with good hole transport characteristics. A 550 nm thick CH3NH3PbCl3 layer is prepared on the prepared hole transport layer to form the perovskite layer, which absorbs solar energy, generates electron-hole pairs, and converts solar energy into electrical energy. A 75 nm thick C60 layer is thermally evaporated on the prepared perovskite layer as the first electron transport layer. A 65 nm thick ZnO layer is prepared on the first electron transport layer by atomic deposition as the second electron transport layer. The solar cell is fabricated by sputtering a 220 nm thick ITO layer onto the second electron transport layer using magnetron sputtering.

[0066] In some embodiments, the magnetron sputtering equipment applies a magnetic field during the magnetron sputtering process to enhance the ion density in the gas, thereby improving the uniformity and quality of the thin film. The target material is a 190 nm thick ITO, which is sintered from 85 wt% In2O3 and 15 wt% SnO2. Under vacuum conditions of 9E-4 Pa, oxygen and argon are introduced at a flow rate of 195 sccm each, and radio frequency is started when the gas pressure reaches 0.4 Pa.

[0067] In some embodiments, during the preparation of the perovskite layer, the T-IBC cell needs to be immersed in and ultrasonically cleaned with an organic solvent such as ethanol or isopropanol, and then dried with nitrogen. The deposition temperature of the CH3NH3PbI3 perovskite layer is between 80°C and 150°C. A heat source or flowing gas can be used to heat the evaporation source, and the evaporation rate is controlled within a certain range during the deposition process. arrive To ensure uniform film deposition, the temperature of the evaporation source is controlled between 100°C and 200°C to adjust the evaporation rate and composition of the material. During the preparation of the CH3NH3PbI3 perovskite layer, evaporation is carried out under an inert gas (such as nitrogen) or a controlled atmosphere (such as chlorine or iodine), and the film thickness is controlled by adjusting the evaporation time.

[0068] In some embodiments, during the sputtering of the ITO layer on the second electron transport layer, the radio frequency is 12.6 MHz, an ITO target material sintered from 85 wt% In2O3 and 15 wt% SnO2 is used, and the thickness of the ITO target material is 220 nm. Under vacuum conditions of 8E-4 Pa, oxygen and argon are filled at a flow rate of 180 sccm, and the radio frequency is started when the gas pressure reaches 0.3 Pa.

[0069] To better illustrate the method for preparing solar cells in this embodiment and improve the photoelectric conversion efficiency of solar cells, the open-circuit voltage (Voc), current density (Jsc), fill factor (FF), and photoelectric conversion efficiency (Eff) of the T-IBC cell, the perovskite stack, and the solar cell were tested by electrical performance IV, and the results are shown in Table 1.

[0070] Table 1. Comparison of Electrical Performance

[0071] type Voc(V) <![CDATA[Jsc(mA / cm 2 )]]> FF (%) Eff(%) Perovskite stack 1.15 17.2 72.3 14.3 T-IBC battery 0.734 32.42 84.25 20.048 Solar cells 34.348

[0072] Due to the difficulty in ensuring completely consistent experimental conditions, the above experimental data contains certain errors, but this does not affect the final experimental results. The solar cell is a stacked composite structure of perovskite tandem and T-IBC cells. As shown in Table 1, the photoelectric conversion efficiency of the solar cell is significantly higher than that of the T-IBC cell and the perovskite tandem. This application increases the doping concentration of the P+ doped region through boron diffusion, thereby reducing the contact resistivity and improving the passivation effect of the cell. Furthermore, the silver paste printed by laser grooving can etch silicon nitride, eliminating the need for laser drilling and effectively reducing the damage to the passivation layer. In addition, through selective emitter laser doping, high-concentration doping is performed in the electrode region, while low-concentration light doping is performed in the light absorption region, thereby reducing the emitter contact resistance and the dark saturation current in the emitter region, increasing the fill factor, short-circuit current, and open-circuit voltage, and improving the cell conversion efficiency.

[0073] Example 2

[0074] This application provides a solar cell (not shown in the figure). The solar cell is prepared by the method of preparing the solar cell in the above embodiment 1. Therefore, it has all the beneficial effects of the method of preparing the solar cell in the above embodiment, which will not be described in detail here.

[0075] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0076] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a solar cell, characterized in that, include: Obtain silicon material and perform a first deposition process on the silicon material to form a passivation contact layer of a predetermined thickness on the first contact surface of the silicon material; After obtaining a phosphorus source and performing phosphorus diffusion on the passivation contact layer, a first mask layer, a second mask layer, and a third mask layer are sequentially formed on the passivation contact layer. After obtaining a boron source and performing boron diffusion on the first contact surface, selective emitter laser doping is performed on the first contact surface to achieve high concentration doping in the electrode region and low concentration light doping in the light absorption region. The silicon material is subjected to a second deposition process to form an aluminum oxide layer on both the first and second contact surfaces of the silicon material.

2. The method for preparing a solar cell according to claim 1, characterized in that, Before performing boron diffusion on the first contact surface, the first contact surface needs to be grooved to form P+ doped regions and N+ doped regions arranged in an interdigitated pattern on the first contact surface. The first contact surface has a positive gate line and a negative gate line. The positive gate line is connected to the P+ doped region, and the negative gate line is connected to the N+ doped region.

3. The method for preparing a solar cell according to claim 2, characterized in that, The method for preparing the solar cell further includes a step of screen printing the silicon material to print silver-aluminum paste in the P+ doped region.

4. The method for preparing a solar cell according to claim 1, characterized in that, The passivated contact layer includes: A silicon oxide layer having a first predetermined thickness, and the silicon oxide layer being located on the first contact surface; A doped silicon layer having a second preset thickness greater than a first preset thickness, and the doped silicon layer being located on the side of the silicon oxide layer away from the first contact surface.

5. The method for preparing a solar cell according to claim 1, characterized in that, The boron source is BCl3, and after boron diffusion occurs on the first contact surface, a borosilicate glass layer is formed on the first contact surface. The borosilicate glass layer is a doping source for selective emitter laser doping.

6. The method for preparing a solar cell according to claim 1, characterized in that, The phosphorus source is POCl3, and the first mask layer is a silicon oxide layer, the second mask layer is a silicon nitride layer, and the third mask layer is silicon oxide.

7. The method for preparing a solar cell according to claim 6, characterized in that, Before performing boron diffusion on the first contact surface, the second contact surface needs to be subjected to thermal oxidation treatment to form a fourth mask layer on the second contact surface, and the fourth mask layer is silicon oxide.

8. The method for preparing a solar cell according to any one of claims 1-7, characterized in that, The silicon material has a first preset sheet resistance after phosphorus diffusion, and the first contact surface needs to be oxidized and degraded during the second deposition process of the silicon material so that the silicon material after the oxidation and degradation process has a second preset sheet resistance. The first preset sheet resistance is 40Ω / sq, and the second preset sheet resistance is 65Ω / sq.

9. The method for preparing a solar cell according to any one of claims 1-7, characterized in that, The method for fabricating the solar cell further includes the step of fabricating a perovskite stack on the second contact surface, wherein the perovskite stack comprises a first conductive layer, a hole transport layer, a perovskite layer, a first electron transport layer, a second electron transport layer, and a second conductive layer that are sequentially stacked on the second contact surface.

10. A solar cell, characterized in that, The solar cell is prepared by the method for preparing a solar cell according to any one of claims 1-9.

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