Preparation method of crystalline silicon solar cell

Abstract

The invention discloses a preparation method of a crystalline silicon solar cell. The preparation method comprises the following steps: arranging a function adjusting layer on and / or in a passivation dielectric layer; electrode slurry is printed on the passivation dielectric layer and corresponds to the position of the function adjusting layer; sintering to form a metal electrode; the function adjusting layer comprises at least one of compounds containing specific cations, the compounds containing the specific cations can release the specific cations at the sintering temperature, and the specific cations are cations corresponding to elements involved in the glass network formation. According to the preparation method, minority carrier recombination can be effectively reduced, the passivation effect of the battery is improved, and the conductivity of the metal electrode is effectively improved.

Description

Technical Field

[0001] The invention relates to a method for preparing a crystalline silicon solar cell. Background Art

[0002] For the structure of preparing metal electrodes by printing metal paste on the front of solar cells, due to the presence of the insulating passivation layer, in order to make the metal electrode form an electrical connection with the silicon substrate, a high-temperature rapid sintering furnace must be used to sinter the printed and dried electrode paste. During the sintering process of the electrode paste, the glass in the electrode paste forms a molten state with fluidity, and after the glass forms a molten state, some silver atoms in the electrode paste dissolve into the glass. The molten silver-containing glass undergoes an oxidation-reduction reaction with the insulating passivation layer, causing part of the insulating passivation layer to be corroded, thereby exposing a small portion of the silicon surface to contact the metal electrode formed by sintering.

[0003] Through research, it was found that due to the fast diffusion rate of silver atoms in the glass, during the sintering process, the silver atoms will leave the glass and reach the surface of the silicon substrate to form nanosilver particles. The nanosilver particles directly contact the surface of the silicon substrate to form metal semiconductor contact, which increases the recombination of minority carriers and reduces the passivation effect of the battery. Furthermore, the number of silver atoms retained in the insulating glass is reduced, resulting in poor conductivity of the formed metal electrode. Summary of the invention

[0004] In view of this, the present invention provides a method for preparing a solar cell, which can effectively reduce minority carrier recombination, improve the passivation effect of the cell, and effectively improve the conductivity of the metal electrode.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] A method for preparing a solar cell, comprising:

[0007] Step 1: Disposing a function adjustment layer on the passivation dielectric layer and / or in the passivation dielectric layer;

[0008] Step 2, printing electrode slurry on the passivation dielectric layer and at a position corresponding to the function adjustment layer;

[0009] Step 3: Sintering to form a metal electrode;

[0010] The function regulating layer includes at least one of compounds containing specific cations, and the compound containing specific cations can release the specific cations at a sintering temperature, and the specific cations are cations corresponding to elements involved in the glass network former.

[0011] The technical solution of the first aspect of the above invention has the following advantages or beneficial effects:

[0012] The technical solution provided by the embodiment of the present invention is to set a function adjustment layer on the passivation dielectric layer and / or in the passivation dielectric layer, and print the electrode paste on the passivation dielectric layer and at a position corresponding to the function adjustment layer. Since the function adjustment layer includes at least one of the compounds containing specific cations, and the compound containing specific cations can release specific cations at the sintering temperature, and the specific cations are cations corresponding to the elements involved in the glass network former, during the sintering process, the specific cations released by the function adjustment layer can melt into the melt of the glass body of the electrode paste to play a role in strengthening the glass network structure, that is, on the one hand, it can increase the viscosity of the melt of the glass body, so that the diffusion rate of metal atoms in the melt of the glass body becomes smaller, and finally a large number of metal ions are retained in the glass body, reducing the probability of silicon matrix and metal atoms recombination, and can effectively reduce minority carrier recombination, thereby improving the battery passivation effect; on the other hand, it can reduce the solubility of the melt of the glass body for metal ions, prompting a large number of metal ions in the melt of the glass body to tend to nucleate and crystallize, so that a large number of uniformly distributed conductive metal particles are formed in the glass body, thereby changing the conductive properties of the glass body. Therefore, the setting of the functional adjustment layer can improve the contact performance between the metal electrode and the silicon substrate, reduce the damage of the electrode slurry sintering to the passivation dielectric layer, enhance the carrier conduction ability, reduce the series resistance, increase the fill factor, and improve the photoelectric conversion efficiency of solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the main process of the method for preparing a solar cell provided by an embodiment of the present invention;

[0014] Figure 2 It is a structural schematic diagram of a first relative relationship between a function adjustment layer and a passivation dielectric layer provided by an embodiment of the present invention;

[0015] Figure 3 It is a structural schematic diagram of a second relative relationship between the function adjustment layer and the passivation dielectric layer provided by an embodiment of the present invention;

[0016] Figure 4 It is a structural schematic diagram of a third relative relationship between the function adjustment layer and the passivation dielectric layer provided by an embodiment of the present invention;

[0017] Figure 5 is a structural schematic diagram of a fourth relative relationship between the function adjustment layer and the passivation dielectric layer provided by an embodiment of the present invention;

[0018] Figure 6 is a schematic diagram of structural changes corresponding to the preparation method provided in an embodiment of the present invention;

[0019] Figure 7 is a scanning electron microscope morphology image of the metal electrode prepared in Example 2;

[0020] Figure 8 is a scanning electron microscope morphology image of the metal electrode prepared in Example 3;

[0021] Fig. 9 is a diagram of the chemical state energy level change of the aluminum element in the function adjustment layer before and after sintering provided by an embodiment of the present invention;

[0022] Fig.10 It is a chemical state energy level change diagram of the silicon element in the function adjustment layer before sintering and the silicon element in the metal electrode formed after sintering provided by an embodiment of the present invention;

[0023] Fig.11 is a diagram showing the chemical state energy level change of the lead element in the metal electrode before and after sintering in the structure prepared in Example 3;

[0024] Fig.12 is a chemical state energy level diagram of the silver element in the metal electrode after sintering in the structure prepared in Example 3;

[0025] Fig.13 is a partial structural schematic diagram of a Topcon solar cell provided in an embodiment of the present invention;

[0026] Fig.14 It is a partial structural schematic diagram of a BC solar cell provided in an embodiment of the present invention.

[0027] The reference numerals are as follows:

[0028] 10-silicon substrate; 20-diffusion doping layer; 30-metal electrode; 31-functional adjustment layer; 32-electrode slurry; 40-tunneling oxide layer; 41-first tunneling oxide layer; 42-second tunneling oxide layer; 50-doped polysilicon layer; 51-first doped polysilicon layer; 52-second doped polysilicon layer; 60-aluminum oxide film layer; 70-passivation anti-reflection layer. DETAILED DESCRIPTION

[0029] For solar cells, a PN junction can be formed in the front or back part of the battery by directly diffusing doping elements on the surface of the silicon substrate, and then a metal electrode is prepared by printing an electrode paste containing a glass body and metal atoms and sintering the electrode paste at high temperature. The glass body in the metal electrode is generally an insulating material with poor conductivity. The conductivity of the metal electrode is mainly determined by the metal atoms. However, during the sintering process, the metal atoms in the metal electrode will separate from the glass body in the metal electrode due to their fast diffusion rate and reach the surface of the silicon substrate and aggregate to form nano-scale metal particles. On the one hand, there are very few metal atoms remaining in the metal electrode, resulting in poor conductivity of the metal electrode; on the other hand, the nano-scale metal particles aggregated on the surface of the silicon substrate are in direct contact with the surface of the silicon substrate, which is a metal-semiconductor contact, which increases the probability of recombination of minority carriers at the contact interface and worsens the battery passivation effect. In particular, for Topcon cells, N-type silicon wafers are used as light-absorbing substrate materials. For the light-receiving side of the Topcon cell, a PN junction is prepared on the surface of the silicon substrate (i.e., the N-type silicon wafer) by high-temperature boron diffusion, and an aluminum oxide passivation film layer, a silicon nitride passivation anti-reflection layer, and a metal electrode are sequentially stacked; for the backlight side of the Topcon cell, a tunneling oxide layer, a phosphorus-doped polysilicon layer, a silicon nitride layer, and a metal electrode are sequentially stacked on the surface of the silicon substrate. For the light-receiving side of the Topcon cell, the diffuse doping layer prepared directly on the surface of the silicon substrate by high-temperature boron diffusion is relatively thin, so that the metal atoms of the metal electrode can easily reach the surface of the silicon substrate to form a metal-semiconductor contact, which increases the probability of recombination of minority carriers and reduces the passivation effect of the cell.

[0030] Through research, it is found that if the amount of metal atoms reaching the surface of the silicon substrate can be reduced, and the metal nanoparticles can be evenly dispersed in the metal electrode (that is, the metal atoms are evenly dispersed in the glass formed by the metal electrode), the conductivity of the metal electrode can be greatly improved, and the tunneling probability of the carrier can be increased, that is, the number of metal nanoparticles in the metal electrode is increased, and the direct contact between the silicon substrate surface and the nano-scale metal particles is reduced, which can further reduce the series resistance of the Topcon battery, thereby improving the photoelectric conversion efficiency of the battery. Based on this, the present invention provides a method for preparing a solar cell, in particular, a method for preparing a metal electrode in a solar cell, and more particularly, a method for preparing a metal electrode on the light-receiving surface of a Topcon battery or a metal electrode of a solar cell with a full back contact structure. It can make the nano-scale metal particles evenly dispersed in the metal electrode and reduce the amount of metal particles reaching the surface of the silicon substrate.

[0031] The embodiments of the present invention involve preparing or arranging another functional layer (such as a functional adjustment layer 31, an electrode slurry, etc.) on a functional layer (such as a passivation dielectric layer), which generally means that, with the functional layer facing upward, another functional layer is prepared or arranged on top of the functional layer.

[0032] The preparation or arrangement of another functional layer (such as the functional adjustment layer 31) in a functional layer (such as a passivation dielectric layer) involved in the embodiments of the present invention generally refers to preparing or arranging another functional layer on the functional layer during the preparation of the functional layer, and after preparing or arranging the other functional layer, further preparing the remaining part of the functional layer so that the other functional layer is located in the functional layer.

[0033] The surface of the silicon substrate 10 involved in the embodiment of the present invention can be a plane structure or a pyramid velvet structure. The velvet structure is generally formed by etching single crystal silicon with an existing alkaline solution or etching polycrystalline silicon with an acid solution. Therefore, the silicon substrate 10 involved in the embodiment of the present invention can be a single crystal silicon substrate or a polycrystalline silicon substrate. In addition, the velvet structure can exist only on one main surface of the silicon substrate 10, or on two main surfaces of the silicon substrate 10. It can be understood that the planar structure of the silicon substrate 10 is only exemplarily shown in the accompanying drawings given in the embodiment of the present invention, and those skilled in the art can know the structural changes of the pyramid velvet structure on the main surface of the silicon substrate 10 based on the prior art.

[0034] in, Figure 1 A schematic diagram showing the main process of the method for preparing a solar cell provided by an embodiment of the present invention is shown. Figures 2 to 5 A structural schematic diagram showing the relative relationship between the function adjustment layer 31 and the passivation dielectric layer provided in an embodiment of the present invention; Figure 6 A schematic diagram of the structural changes corresponding to the preparation method is shown.

[0035] It is worth noting that the above-mentioned preparation method provided in the embodiment of the present invention can be used to prepare Topcon cells or BC type solar cells.

[0036] Specifically, Figure 1 As shown, a method for preparing a crystalline silicon solar cell provided by an embodiment of the present invention may include the following steps:

[0037] Step S101: disposing a function adjustment layer 31 on the passivation dielectric layer and / or in the passivation dielectric layer.

[0038] Furthermore, if the crystalline silicon solar cell is a Topcon solar cell, the following steps are further included before step S101:

[0039] A first type doped layer is formed on the light-receiving surface of the silicon substrate 10, and a tunneling oxide layer 40 and a second type doped polysilicon layer are sequentially prepared on the backlight surface of the silicon substrate 10, and then a passivation dielectric layer is prepared on the first type doped layer and the second type doped polysilicon layer, respectively. The doping type in the first type doped layer is opposite to the type of the silicon substrate 10, and the doping type in the second type doped polysilicon layer is consistent with the type of the silicon substrate 10. For example, the type of the silicon substrate 10 is an N-type silicon substrate, the doping type in the first type doped layer is P-type doping, and the doping type of the second type doped polysilicon layer is N-type doping; the type of the silicon substrate 10 is a P-type silicon substrate, the doping type in the first type doped layer is N-type doping; the doping type of the second type doped polysilicon layer is P-type doping.

[0040] Exemplarily, boron diffusion is performed on the light-receiving surface of the N-type silicon substrate to form a boron-doped layer (the boron-doped layer is the diffusion-doped layer 20), and a tunneling oxide layer 40 and a phosphorus-doped polysilicon layer (i.e., the doped polysilicon layer 50) are sequentially prepared on the backlight surface of the silicon substrate 10, and then a passivation dielectric layer is prepared on the boron-doped layer and the phosphorus-doped polysilicon layer 50, respectively.

[0041] For the structure of Topcon solar cell, step S101 is specifically as follows: Figures 2 to 4 As shown, a function adjustment layer 31 is arranged on the passivation medium layer of the light-receiving surface of the Topcon solar cell or / and in the passivation medium layer.

[0042] In addition, when the crystalline silicon solar cell is a BC solar cell, the following steps are also included before step S101:

[0043] An n-type region and a p-type region are formed on the backlight surface of the silicon substrate 10, and a passivation dielectric layer is formed on the surface of the n-type region, the surface of the p-type region, and the surface of the silicon substrate 10 between the n-type region and the p-type region.

[0044] like Figure 5 As shown, the n-type region includes a first tunneling oxide layer 41 arranged on the backlight side of the silicon substrate 10, and an n-type doped silicon layer 51 arranged on the first tunneling oxide layer 41; the p-type region includes a second tunneling oxide layer 42 arranged on the backlight side of the silicon substrate, and a p-type doped silicon layer 52 arranged on the second tunneling oxide layer 42.

[0045] For the structure of the BC solar cell, the step S101 specifically includes: setting a function adjustment layer 31 on the passivation dielectric layer corresponding to the n-type region or / and in the passivation dielectric layer; setting a function adjustment layer 31 on the passivation dielectric layer corresponding to the p-type region or / and in the passivation dielectric layer. For example, Figure 5 As shown, a function adjustment layer 31 is provided on the passivation dielectric layer corresponding to the n-type region, and a function adjustment layer 31 is provided on the passivation dielectric layer corresponding to the p-type region.

[0046] Among them, Figures 2 to 4 As shown, the function adjustment layer 31 can be located on the light receiving surface of the solar cell. Figure 5 As shown, the function adjustment layer 31 may also be located on the backlight side of the solar cell.

[0047] The passivation dielectric layer involved in step S101 may be a single layer or a stacked functional layer. For example, the passivation dielectric layer may be a passivation anti-reflection layer 70 stacked on the side of the diffusion doping layer 20 away from the silicon substrate 10 or the side of the doped polysilicon layer away from the silicon substrate 10; the passivation dielectric layer may also be an aluminum oxide film layer 60 stacked on the side of the diffusion doping layer 20 away from the silicon substrate 10 or the side of the doped polysilicon layer 50 away from the silicon substrate 10; the passivation dielectric layer may also be a stacked structure formed by the aluminum oxide film layer 60 and the passivation anti-reflection layer 70, specifically, the aluminum oxide film layer 60 is located on the side of the diffusion doping layer 20 or the doped polysilicon layer 50 away from the silicon substrate 10, and the passivation anti-reflection layer 70 is stacked on the aluminum oxide film layer 60. For example, Figures 2 to 4 As shown, the passivation dielectric layer is a stacked structure formed by an aluminum oxide film layer 60 and a passivation anti-reflection layer 70; Figure 5 As shown, the passivation dielectric layer is a passivation anti-reflection layer 70 .

[0048] Preferably, the passivation dielectric layer involved in this step is a single layer or a stacked functional layer located on the side of the diffusion doping layer 20 away from the silicon substrate 10, wherein the diffusion doping layer 20 is generally formed by diffusion doping directly on the main surface of the silicon substrate 10. For example, for an N-type silicon substrate, the diffusion doping layer 20 is formed by diffusion doping boron and other P-type doping elements directly on the surface of the N-type silicon substrate; for a P-type silicon substrate, the diffusion doping layer 20 is formed by diffusion doping phosphorus and other N-type doping elements directly on the surface of the P-type silicon substrate. The diffusion doping layer 20 is located on the light-receiving surface of the solar cell, and can also be located on the backlight surface of the solar cell.

[0049] The following takes the stacked structure of the aluminum oxide film layer 60 and the passivation anti-reflection layer 70 as an example of the passivation dielectric layer to describe in detail the position of the function adjustment layer 31. Figure 2 As shown, the function adjustment layer 31 can be disposed on the surface of the aluminum oxide film layer 60; Figure 3 As shown, the function adjustment layer 31 can also be disposed in the passivation anti-reflection layer 70; in addition, as Figure 4As shown, the functional adjustment layer 31 can also be arranged on the passivation anti-reflection layer 70. Furthermore, a multi-layer functional adjustment layer 31 can also be arranged, and the multi-layer functional adjustment layer 31 can be arranged on any one of the surface of the aluminum oxide film layer 60, in the passivation anti-reflection layer 70, and on the passivation anti-reflection layer 70, wherein in the thickness direction, the multi-layer functional adjustment layer 31 corresponds. For example, one layer of functional adjustment layer 31 is arranged on the surface of the aluminum oxide film layer 60, and another layer of functional adjustment layer 31 is arranged on the passivation anti-reflection layer 70, and the two layers of functional adjustment layers 31 correspond; for example, in the corresponding two layers of functional adjustment layers 31, one layer of functional adjustment layer 31 is arranged in the passivation anti-reflection layer 70, and the other layer of functional adjustment layer 31 is arranged on the passivation anti-reflection layer 70, etc. It is worth noting that Figures 2 to 4 The structure of providing the function adjustment layer 31 on the front side of the solar cell is only given as an example. Figure 5 Only an exemplary structure of setting a function adjustment layer 31 on the back of a solar cell is given. For the structure of setting a diffuse doping layer 20 on the back of a solar cell, its function adjustment layer 31 can also be set on the surface of the aluminum oxide film layer 60 and / or in the passivation anti-reflection layer 70.

[0050] The function adjustment layer 31 can be laid on the entire main surface of the passivation dielectric layer. It can also be dispersed. Preferably, in order to reduce the waste of materials used to form the function adjustment layer 31, the specific implementation of this step can be to set multiple function adjustment layers 31 at intervals, that is, the number of function adjustment layers 31 set by this step is multiple, the multiple function adjustment layers 31 are set at intervals, and the multiple function adjustment layers 31 correspond to the multiple metal electrodes 30 one by one.

[0051] Further, the function adjustment layer 31 formed in step S101 may be a single-layer structure or a multi-layer stacked structure. Preferably, the thickness of the function adjustment layer 31 may be 1-20 nm, for example, the thickness of the function adjustment layer 31 may be 1 nm, 2 nm, 5 nm, 8 nm, 10 nm, 14 nm, 15 nm, 17 nm, 20 nm, etc. By adjusting the thickness of the function adjustment layer 31, the subsequent sintering process is facilitated, and the compound containing specific cations included in the function adjustment layer 31 can diffuse in the electrode slurry 32 and be evenly dispersed in the electrode slurry 32, so that the glass body in the electrode slurry 32 can react as much as possible with the specific cations released by the compound containing specific cations in the function adjustment layer 31 to form a reinforced glass network structure (i.e., specific cations are introduced into the glass network structure), which helps the metal atoms in the subsequently printed electrode slurry 32 to polymerize to form nano-scale metal particles, and the nano-scale metal particles are wrapped by the reinforced glass network structure with the introduction of specific cations, which helps the nano-scale metal particles to be evenly dispersed in the metal electrode 30.

[0052] The specific implementation method of this step can be: using a gas that can form a compound containing specific cations as a reaction precursor, using a chemical vapor deposition method (such as plasma enhanced chemical vapor deposition (PECVD) and low pressure chemical vapor deposition (LECVD)) to deposit the functional adjustment layer 31; for example, for the compound containing specific cations is SiAl x O y , a mixture of trimethylaluminum (TMAL), an organic silicon compound (such as silane) and laughing gas can be used as a reaction precursor, and chemical vapor deposition can be used to obtain a compound SiAl containing specific cations (silicon ions and aluminum ions). x O y . The flow rate of each component in the reaction precursor can be regulated according to the actual process requirements. For example, for the process of using a mixed gas of trimethylaluminum (TMAL), an organosilicon compound (such as silane) and laughing gas as a reaction precursor to form a functional adjustment layer 31, the flow ratio of trimethylaluminum (TMAL) to the organosilicon compound can be between 0.05 and 20; the flow ratio of laughing gas to the total flow of organic matter is between 1 and 20. For example, the flow ratio of trimethylaluminum (TMAL) to the organosilicon compound can be 0.05, 0.5, 1, 5, 10, 12, 15, 20, etc. For another example, the flow ratio of laughing gas to (the total flow of trimethylaluminum (TMAL) and the organosilicon compound) can be 1, 1.5, 2, 4, 5, 8, 10, 15, 17, 20, etc.

[0053] Specifically, the specific cations may be cations of at least one of the following elements: germanium, gallium, silicon, lanthanum, aluminum, and zirconium. The compounds containing the specific cations may include: Ga2O3, GeO2, SiAl x O y and SiGe x Al y O z It is worth noting that the raw materials used to form compounds containing specific cations are generally materials that can be vaporized, such as: TMAL (trimethylaluminum), TMA (methyltrimethoxyaluminum), GeH4, GeF4, TMGa (trimethylgallium), C8H 24 N4Zr (tetrakis(dimethylamino)zirconium), SiH4, CH3SiH3 or Si2H4, etc.

[0054] Step S102 : printing the electrode paste 32 on the passivation dielectric layer and at a position corresponding to the function adjustment layer 31 .

[0055] Among them, the electrode slurry 32 generally includes glass and metal atoms;

[0056] The electrode slurry 32 can be directly selected from the existing slurry for making the metal electrode 30 of the battery. The metal atoms in the electrode slurry 32 can be any one or more of silver atoms, copper atoms, platinum atoms, etc. Preferably, the metal atoms in the electrode slurry 32 are silver atoms.

[0057] Specifically, the viscosity of the electrode slurry 32 printed in this step can be 50Pa.s~420Pa.s, and the solid content of the electrode slurry 32 is generally greater than 80%, wherein the viscosity of the electrode slurry 32 refers to the viscosity measured by stirring the electrode slurry 32 at 10 rpm with a No. 14 rotor at 25°C. By selecting the above viscosity and the solid content of the electrode slurry 32, the concentration of dissolved metal atoms in the glass body in the initial stage of sintering is sufficiently high, and the composition and performance of the glass body in the electrode slurry 32 tend to be low viscosity, high silver solubility and high metal atom diffusion rate. In the later stage of sintering, due to the introduction of the functional adjustment layer 31, the specific cations released by the functional adjustment layer 31 melt into the melt of the glass body of the electrode slurry. The specific cations can gather and strengthen the glass network structure formed, inhibit the diffusion of metal atoms, and make the electrode slurry 32 have high viscosity, low metal diffusion rate, and metal crystallization tendency. Therefore, by controlling the viscosity of the electrode slurry 32, the electrode slurry 32 can flow and fully contact with the specific cations in the functional adjustment layer 31, and the viscosity of the electrode slurry 32 cooperates with the functional adjustment layer 31 to reduce the contact area between the metal electrode 30 and the surface of the silicon substrate 10, thereby reducing the semiconductor-metal recombination of the solar cell, so as to effectively reduce the probability of carrier recombination and enhance the carrier tunneling effect.

[0058] Furthermore, the thickness of the electrode paste 32 printed in this step can be 5 μm to 30 μm. For example, the thickness of the electrode paste 32 can be 5 μm, 10 μm, 15 μm, 20 μm, 25 μm or 30 μm. By controlling the thickness of the electrode paste 32, the electrical contact structure can be formed by sintering, and at the same time, the exposed part of the formed metal electrode 30 can form a stable electrical connection with the connecting parts such as the welding strip and the bus bar, thereby ensuring the stability of the photovoltaic module prepared subsequently by the solar cell.

[0059] In a preferred embodiment, the electrode slurry 32 selected in this step is generally a high-temperature sintering slurry. The high-temperature sintering slurry involved in the embodiment of the present invention is generally an electrode slurry 32 that can meet the sintering temperature of 600°C to 900°C.

[0060] Step S103 : sintering to form the metal electrode 30 .

[0061] Among them, in the process of forming the metal electrode 30, the specific cations released by the functional adjustment layer 31 participate in the process of the glass body in the electrode slurry 32 forming a glass network structure, that is, specific cations are introduced into the glass network structure. After the introduction of specific cations, the glass network structure can block the metal atoms in the metal electrode 30 from diffusing to the surface of the silicon substrate, and can make the metal atoms evenly dispersed in the metal electrode 30.

[0062] The sintering in this step is generally performed at high temperature. The high temperature sintering temperature is generally 600°C to 900°C. For example, the high temperature sintering temperature may be 600°C, 650°C, 700°C, 750°C, 800°C, 850°C or 900°C. The high temperature sintering can be performed directly using the existing sintering process of solar cells.

[0063] Specifically, the specific implementation of step S103 may include: the glass in the electrode slurry 32 burns through the passivation dielectric layer; the electrode slurry 32 flows, so that the molten functional adjustment layer 31 is melted into the electrode slurry 32, and the specific cations released by the functional adjustment layer 31 enter the glass, playing a role in strengthening the glass network structure. Taking the laminated structure formed by the passivation dielectric layer being the aluminum oxide film layer 60 and the passivation anti-reflection layer 70, and the functional adjustment layer 31 being located on the aluminum oxide film layer 60 as an example, after the above steps S101 to S103, the structure changes as follows: Figure 6 As shown. Figure 6 It can be seen that in the structure formed by the above steps S101 and S102, during the sintering process, after the electrode slurry 32 burns through the passivation dielectric layer (the passivation anti-reflection layer 70 and the aluminum oxide film layer 60), the electrode slurry 32 flows, so that the molten function adjustment layer 31 is melted into the electrode slurry 32, and after sintering, the structure is formed as shown in FIG. Figure 6 The metal electrode 30 is shown.

[0064] It is worth noting that when the electrode slurry 32 is used alone, the glass body therein can form a glass network structure by itself. However, after being processed by the above technical solution provided by the embodiment of the present invention, the specific cations contained in the function adjustment layer 31 react with the glass body in the electrode slurry 32 to form a reinforced glass network structure (the reinforced glass network structure includes the glass body and the specific cations), which is different from the glass network structure formed by the glass body itself and the glass network structure formed by the compound containing the specific cations itself. Specifically, by comparing the morphology of the metal electrode 30 prepared by the prior art and the morphology of the metal electrode 30 prepared by the preparation method provided by the embodiment of the present invention ( Figure 7 The morphology of the metal electrode 30 prepared by the prior art after being immersed in an acid solution is shown. Figure 8The morphology of the metal electrode 30 prepared in the embodiment of the present invention after being immersed in an acid solution is shown. For the metal electrode 30 prepared in the embodiment of the present invention, the SiAl x O y The functional adjustment layer 31 is taken as an example for explanation), wherein, regardless of whether it is a metal electrode prepared by the prior art or a metal electrode 30 prepared by the technical solution provided in an embodiment of the present invention, after acid immersion, the glass network structure in the metal electrode (the metal electrode prepared by the prior art or the metal electrode 30 prepared by the technical solution provided in an embodiment of the present invention) is not destroyed, but the metal atoms in the metal electrode (the metal electrode prepared by the prior art or the metal electrode 30 prepared by the technical solution provided in an embodiment of the present invention) that are not wrapped by the glass network structure can be leached. The acid immersion determines whether the metal atoms in the metal electrode 30 are immersed in the acid solution, indicating whether the metal atoms in the metal electrode (the metal electrode prepared by the prior art or the metal electrode 30 prepared by the technical solution provided in an embodiment of the present invention) can migrate and whether they are easy to contact with the silicon substrate.

[0065] Furthermore, if Figure 7 As shown in the figure, after the metal electrode prepared by the prior art is soaked in acid, the metal atoms or agglomerated metal particles remaining in the metal electrode are rare, indicating that in the metal electrode prepared by the prior art, most of the metal elements or metal particles can be easily migrated and leached into the acid solution. The migration of these metal elements or metal particles can greatly increase the probability of the metal elements or metal particles contacting the silicon substrate. Therefore, the metal electrode prepared by the prior art is prone to metal compounding on the surface of the silicon substrate. Figure 8 As shown, after the metal electrode 30 prepared by the embodiment of the present invention is soaked in acid, a large number of agglomerated metal particles (generally nanometer-sized) still exist in the metal electrode 30, and these metal particles are still evenly distributed in the metal electrode 30. This shows that in the metal electrode 30 prepared by the embodiment of the present invention, a large number of metal particles are dispersed by the reinforced glass network structure formed by the glass body and specific cations, and the reinforced glass network structure blocks the migration space of the metal particles, so that a large number of metal ions are retained in the glass body. These metal particles cannot migrate freely, which greatly reduces the probability of metal particles contacting the silicon substrate 10. Therefore, the metal electrode 30 prepared by the embodiment of the present invention effectively reduces the metal recombination between the metal particles and the surface of the silicon substrate 10, and can effectively reduce the recombination of minority carriers, thereby improving the passivation effect of the battery. In addition, from Figure 7It can be seen that in the metal electrode prepared by the prior art, the glass network structure formed in the metal electrode is in an agglomerated state. Compared with the prior art, it is shown that in the solution provided by the embodiment of the present invention, by introducing specific cations, the solubility of the glass melt for metal ions can be reduced, and a large number of metal ions in the glass melt tend to nucleate and crystallize, so that a large number of uniformly distributed conductive metal particles are formed in the glass, thereby changing the conductive properties of the glass. Figure 8 It can be seen that the reinforced glass network structure formed in the metal electrode 30 prepared in the embodiment of the present invention is dispersed relatively evenly in the metal electrode 30. Therefore, the provision of the function adjustment layer 31 can improve the contact performance between the metal electrode 30 and the silicon substrate 10, reduce the damage of the passivation dielectric layer caused by the sintering of the electrode slurry 32, enhance the carrier conduction capability, reduce the series resistance, improve the filling factor, and improve the photoelectric conversion efficiency of the solar cell.

[0066] Further, the valence energy level of the element contained in the function adjustment layer 31, the energy level valence change of some ions in the electrode slurry 32, and the valence energy level change of the element in the metal electrode 30 formed in the embodiment of the present invention are compared (the function adjustment layer 31 contains SiAl x O y For example, SiAl x O y The silicon ions and aluminum ions in the solution are the above-mentioned specific cations. Fig. 9 The comparison of the energy level changes of the aluminum ion valence state before and after sintering is given as an example. Fig.10 The comparison of the valence energy level changes of silicon ions before and after sintering is given as an example. Fig.11 The energy level valence comparison of the lead ions in the electrode slurry 32 before sintering and the lead ions in the metal electrode 30 after sintering is given as an example. Fig.12 The energy level valence state of silver in the metal electrode 30 of the embodiment of the present invention is given as an example. Figures 9 to 11 Combination Figure 8 It can be found that in the electrode slurry 32, after sintering, the aluminum ions and silicon ions in the function adjustment layer 31 enter the metal electrode 30, and the valence state of the aluminum ions and silicon ions changes, indicating that the aluminum ions and silicon ions in the function adjustment layer 31 react with the glass body after entering the electrode slurry 32. This also proves that the valence state of the specific cations (aluminum ions and silicon ions) in the function adjustment layer 31 has changed, indicating that they participate in the glass body network structure, changing the glass network structure and the lead element bonding structure in the glass network structure (such as Fig.11As shown in the figure, after the functional adjustment layer 31 is introduced, the lead element undergoes a significant change in valence energy level), that is, a strengthened glass network structure is formed (the strengthened glass network structure is different from the glass network structure of the metal electrode in the prior art). The strengthened glass network structure can cause metal atoms to precipitate and aggregate into nano-scale metal particles, and the strengthened glass network structure can wrap the nano-scale metal particles or prevent the migration of the nano-scale metal particles, so that the nano-scale metal particles can be dispersed more evenly on the formed metal electrode 30, and prevent the nano-scale metal particles from contacting the silicon substrate 10.

[0067] In addition, from Fig.12 The valence distribution of silver in the metal electrode 30 formed after sintering according to the technical solution provided in the embodiment of the present invention can be seen. After the above treatment, the metallic silver can be detected and the content is relatively high. Figure 8 From the scanned morphology, we can see that Figure 8 The uniformly dispersed particles in the above are metallic silver. Figures 8 to 12 The preparation process of the structure will be described in detail in the following specific embodiments and will not be repeated here.

[0068] In addition, in the embodiment of the present invention, specific cations released by the function adjustment layer 31 enter the electrode slurry 32, and the molten glass in the electrode slurry 32 combines with the specific cations to form a reinforced glass network structure, and the viscosity of the reinforced glass network structure increases; the diffusion rate of metal atoms in the electrode slurry 32 decreases, which reduces the diffusion of metal atoms into the silicon substrate 10, and is beneficial to the nucleation and crystallization of metal atoms, so that a large number of molten metal atoms are agglomerated and retained and dispersed in the metal electrode 30.

[0069] In addition, the presence of the function adjustment layer 31 can also inhibit the electrode slurry 32 from moving toward the surface of the silicon substrate 10, reducing the contact between the formed metal electrode 30 and the silicon substrate 10, thereby effectively reducing the recombination between the metal electrode 30 and the surface of the silicon substrate 10 to reduce carrier recombination.

[0070] Further, in step S103, during the formation of the metal electrode 30, the reinforced glass network structure causes the metal atoms in the metal electrode 30 to crystallize and agglomerate to form nano-scale metal particles. The reinforced glass network structure can wrap the nano-scale metal particles or block the migration space of the nano-scale metal particles, thereby limiting the migration and accumulation of the metal particles to the surface of the silicon substrate 10. In other words, after the specific cations released by the functional adjustment layer 31 enter the molten glass body in the electrode slurry 32, the polymerization of the reinforced glass body is strengthened to form a reinforced glass network structure, which reduces the solubility of the glass body to the metal atoms, and the metal atoms in the glass body begin to crystallize from the glass body and form nano-scale metal particles, and the metal particles are evenly distributed in the reinforced glass network structure. A large number of evenly distributed nano-metal particles can increase the probability of carrier tunneling, thereby improving the conductivity of the interface glass body, improving the series resistance of the battery, and improving the photoelectric conversion efficiency of the battery.

[0071] Compared with the existing solar cells in which the metal electrodes are formed by sintering the electrode slurry, the technical solution provided by the present invention only has the above-mentioned step S101, which can use a chemical vapor deposition process (such as plasma enhanced chemical vapor deposition (PECVD), low pressure chemical vapor deposition (LECVD)) to deposit the functional adjustment layer 31. The chemical vapor deposition process is a commonly used process in solar cells. For example, the tunneling oxide layer, the doped polysilicon layer, etc. can all be completed by chemical vapor deposition. Therefore, the above-mentioned step S101 can be directly completed by using the existing equipment for preparing various functional layers of solar cells without adding new equipment, so that the production cost of solar cells can be controlled.

[0072] In summary, the technical solution provided by the embodiment of the present invention is to provide a function adjustment layer 31 on and / or in the passivation dielectric layer, and print the electrode paste on the passivation dielectric layer and at a position corresponding to the function adjustment layer 31. Since the function adjustment layer 31 includes at least one of the compounds containing specific cations, and the compound containing specific cations can release specific cations at the sintering temperature, and the specific cations are cations corresponding to the elements involved in the glass network formation, during the sintering process, the specific cations released by the function adjustment layer 31 can melt into the melt of the glass body of the electrode paste 32. The function of the functional adjustment layer 31 is to strengthen the glass network structure, that is, on the one hand, it can increase the viscosity of the glass melt, so that the diffusion rate of metal atoms in the glass melt becomes smaller, and finally a large number of metal ions are retained in the glass, reducing the probability of the silicon substrate 10 and the metal atoms being combined, and can effectively reduce the minority carrier recombination, and improve the battery passivation effect; on the other hand, it can reduce the solubility of the glass melt for metal ions, and promote a large number of metal ions in the glass melt to tend to nucleate and crystallize, so that a large number of uniformly distributed conductive metal particles are formed in the glass, thereby changing the conductive properties of the glass. Therefore, the setting of the functional adjustment layer 31 can improve the contact performance between the metal electrode 30 and the silicon substrate 10, reduce the damage of the electrode slurry sintering to the passivation dielectric layer, enhance the carrier conduction ability, reduce the series resistance, improve the filling factor, and improve the photoelectric conversion efficiency of the solar cell.

[0073] In addition, during the sintering process, by selecting high-temperature sintering, the strengthened glass network structure formed is more conducive to the crystallization of metal atoms in the electrode slurry 32, and the crystallized metal atoms agglomerate or polymerize to form nano-scale metal particles. The existence of the strengthened glass network structure enables the nano-scale metal particles to be evenly dispersed in the metal electrode 30, thereby improving the conductivity of the metal electrode 30 and reducing the metal atoms reaching the surface of the silicon substrate 10, thereby effectively reducing carrier recombination and improving the metal electrode 30's ability to transmit carriers, thereby effectively improving the photoelectric conversion efficiency of the solar cell.

[0074] Furthermore, an embodiment of the present invention also provides a crystalline silicon solar cell prepared by the preparation method provided in the above embodiment. Fig.13 As shown, the crystalline silicon solar cell may include: a silicon substrate 10, a diffusion doping layer 20 arranged on the surface of the silicon substrate 10, and a metal electrode 30 electrically connected to the diffusion doping layer 20, wherein the metal electrode 30 includes a reinforced glass network structure, wherein the reinforced glass network structure is used to block the metal atoms in the metal electrode 30 from diffusing to the surface of the silicon substrate 10, and the reinforced glass network structure is formed by specific cations released by the functional adjustment layer 31 and the glass body in the electrode slurry 32.

[0075] It is worth noting that the crystalline silicon solar cell provided in the embodiment of the present invention may be a Topcon solar cell or a BC solar cell.

[0076] Furthermore, the metal electrode 30 includes: uniformly distributed nano-scale metal particles formed by aggregation of metal atoms.

[0077] In addition, for Topcon batteries, such as Fig.13 As shown, the Topcon cell may further include: a tunneling oxide layer 40 disposed on the surface of the silicon substrate 10 and a doped polysilicon layer 50 stacked on the tunneling oxide layer 40 .

[0078] The relative position relationship between the tunnel oxide layer 40 and the diffusion doping layer 20 can be as follows: Fig.13 As shown, the tunneling oxide layer 40 and the diffusion doping layer 20 are respectively disposed on two main surfaces of the silicon substrate 10 .

[0079] For example, in a Topcon cell, the tunneling oxide layer 40 and the diffusion doping layer 20 are disposed on two main surfaces.

[0080] The main surface where the tunnel oxide layer 40 is located is the back side of the solar cell;

[0081] The main surface where the diffuse doping layer 20 is located is the light-receiving surface of the solar cell.

[0082] Furthermore, if Fig.13 As shown, an aluminum oxide film layer 60 and a passivation anti-reflection layer 70 are stacked on the diffusion doping layer 20, and a passivation anti-reflection layer 70 is stacked on the doped polysilicon layer 50. The metal electrode 30 disposed on the back of the crystalline silicon solar cell is formed by directly printing an electrode paste 32 through the prior art and sintering the electrode paste 32.

[0083] The reinforced glass network structure in the metal electrode 30 of the solar cell provided in the embodiment of the present invention can make the metal atoms in the formed metal electrode 30 evenly distributed, so as to effectively reduce the recombination of minority carriers, improve the passivation effect of the battery, and effectively improve the conductivity of the metal electrode 30.

[0084] In addition, for the BC solar cell, it may include a passivation dielectric layer disposed on the light-receiving surface of the silicon substrate 10; and Fig.14 As shown, n-type regions and p-type regions are alternately distributed on the backlight surface of the silicon substrate 10, and a passivation dielectric layer (the passivation dielectric layer is a passivation anti-reflection layer 70) is disposed on the surface of the n-type region, the surface of the p-type region, and the surface of the silicon substrate 10 between the n-type region and the p-type region;

[0085] The n-type region includes a first tunneling oxide layer 41 arranged on the backlight surface of the silicon substrate 10, and an n-type doped silicon layer 51 arranged on the first tunneling oxide layer 41; the p-type region includes a second tunneling oxide layer 42 arranged on the backlight surface of the silicon substrate 10, and a p-type doped silicon layer 52 arranged on the second tunneling oxide layer 42; and metal electrodes 30 are respectively arranged in the n-type region and the p-type region, wherein the metal electrode 30 arranged in the n-type region passes through the passivation dielectric layer and is electrically connected to the n-type doped silicon layer 51; the metal electrode 30 arranged in the p-type region passes through the passivation dielectric layer and is electrically connected to the p-type doped silicon layer 52.

[0086] Furthermore, the following will focus on the above Figures 7 to 12 The preparation process of the structure involved in the characterization and the obtained structure are described in detail to clearly illustrate the technical solution provided by the embodiment of the present invention for changing the enhanced glass network structure and metal particles in the metal electrode 30.

[0087] Example 1: A function adjustment layer before sintering is prepared by a PECVD method, and the function adjustment layer is characterized to illustrate the valence energy level of the elements in the function adjustment layer before the function adjustment layer is combined with the electrode slurry.

[0088] Specifically, the embodiment 1 includes the following steps:

[0089] Step A1: Select a silicon substrate. Select a single crystal n-type silicon wafer with a bulk resistivity of 2.0 Ω•cm.

[0090] Step B1: polishing and cleaning the silicon substrate surface. A potassium hydroxide alkaline solution with a mass fraction of 30% is used to isotropically etch the single crystal n-type silicon wafer to obtain a relatively flat single crystal n-type silicon wafer surface with a reflectivity greater than 35%.

[0091] Step C1: depositing a function adjustment layer on the surface of the silicon substrate.

[0092] The functional adjustment layer was prepared on the surface of a single crystal n-type silicon wafer using the PECVD method. The frequency of the RF power supply was 13.56 MHz, and the RF power range was 30 mW / cm^2. A mixed gas of TMAL, an organic silicon compound, and nitrous oxide with a flow ratio of 1:1:8 was used as a reaction precursor, and the pressure of the reaction chamber was set to 100 Pa. A film layer containing aluminum, silicon, and oxygen with a thickness of 20 nm was obtained, namely the functional adjustment layer.

[0093] Step D1: Measuring the chemical valence state of the aluminum oxide silicon element in the function adjustment layer, that is, obtaining Fig. 9 The valence energy level diagram of aluminum contained in the function adjustment layer before sintering in the chemical state energy level change diagram of aluminum element shown in FIG. Fig.10 The chemical state energy level change diagram of silicon element shown in the figure shows the valence energy level diagram of silicon contained in the functional adjustment layer before sintering.

[0094] Example 2: A metal electrode was prepared by the existing technology (printing high-temperature silver paste, high-temperature sintering), and cleaned by an acid solution to illustrate whether the metal elements in the metal electrode would be leached out.

[0095] The steps of this embodiment 2 are as follows:

[0096] Step A2: Selecting a silicon substrate: A single crystal n-type silicon substrate is selected, and its bulk resistivity is 2.0 Ω•cm.

[0097] Step B2: Polishing and cleaning the silicon substrate surface. A potassium hydroxide alkaline solution with a mass fraction of 30% is used to isotropically etch the single crystal n-type silicon wafer to obtain a relatively flat silicon substrate surface with a reflectivity greater than 35%.

[0098] Step C2: depositing a 5-nanometer aluminum oxide passivation film layer on the surface.

[0099] Step D2: depositing a 78 nanometer silicon nitride film layer on the surface of aluminum oxide.

[0100] Step E2: printing high-temperature sintering silver paste on the surface of the silicon nitride film, and performing rapid high-temperature sintering after drying.

[0101] Step F2: Use a mixture of hydrochloric acid and nitric acid to clean and remove the metal silver electrode. The molar concentration ratio of the mixture (HCl:HNO3:H2O) is 10:10:80. Since silver will dissolve in the mixture, but the glass body will not dissolve in the mixture, the glass structure can be retained on the surface of the silicon substrate after sufficient immersion.

[0102] The results are as follows Figure 7 As shown, in the metal electrode directly prepared by the prior art, there are few large silver particles, which indicates that the glass structure formed in the metal electrode formed by the prior art cannot prevent the migration of metallic silver, resulting in the silver in the metal electrode easily migrating to contact the silicon substrate, and the silver dispersion is poor.

[0103] Example 3: A functional adjustment layer is prepared by a PECVD method, and after the functional adjustment layer is prepared, a high-temperature silver paste is printed, and a metal electrode introduced with specific cations is obtained by high-temperature sintering, and the structure is characterized after cleaning. The characterization of the structure prepared by this Example 3 is compared with the characterization of the structures prepared by Examples 1 and 2, illustrating the effect of the introduction of the functional adjustment layer on the formation of a metal electrode by the electrode slurry.

[0104] The steps of this embodiment 3 are as follows:

[0105] Step A3: Selecting a silicon substrate: A single crystal n-type silicon substrate is selected, and its bulk resistivity is 2.0 Ω•cm.

[0106] Step B3: polishing and cleaning the silicon substrate surface. A potassium hydroxide alkaline solution with a mass fraction of 30% is used to isotropically etch the single crystal n-type silicon wafer to obtain a relatively flat single crystal n-type silicon wafer surface with a reflectivity greater than 35%.

[0107] Step C3: deposit a 4-nanometer aluminum oxide passivation film layer on the surface.

[0108] Step D3: a 5 nm thick functional adjustment layer is disposed on the surface of the aluminum oxide film, and the deposition parameters thereof are similar to those in Example 1.

[0109] Step E3: depositing a 78 nanometer silicon nitride film layer on the surface of the aluminum oxide.

[0110] Step F3: printing high-temperature sintering silver paste on the surface of the silicon nitride film, and performing rapid high-temperature sintering after drying.

[0111] Step G3: Use a mixture of hydrochloric acid and nitric acid to clean and remove the metal silver electrode. The molar concentration ratio of the mixture (HCl:HNO3:H2O) is 10:10:80. Since silver will dissolve in the mixture, but the glass body will not dissolve in the mixture, the glass structure can be retained on the surface of the single crystal n-type silicon wafer after sufficient immersion. The results are as follows Figure 8 As shown, even after immersion, a large number of silver particles are still distributed in the reinforced glass network structure of the metal electrode, and the retained silver particles can still exist in the reinforced glass network structure. Therefore, the setting of the functional adjustment layer helps to evenly disperse the silver particles in the metal electrode.

[0112] Step H3: Characterize the chemical composition and atomic chemical valence of the metal electrode after immersion in step G3. Fig. 9 The valence energy level diagram of aluminum in the metal electrode after sintering is shown in Figure 2. Fig.10 The valence energy level diagram of silicon in the sintered metal electrode is shown, and Fig.11 The valence energy level diagram of lead atoms in the glass before and after sintering is shown in Figure 2. Fig.12 The valence energy level diagram of silver atoms in the metal electrode after sintering is shown in Figure 2. Fig. 9 and Fig.10 It can be seen that after high-temperature sintering, the chemical states of aluminum and silicon elements change, which confirms that specific cations (aluminum ions and silicon ions) in the functional adjustment layer enter the glass in the electrode slurry, causing the coordination environment of the glass element atoms to change. Fig.11 and Fig.12 Combination Figure 8 As shown in the figure, the white particles existing in the glass mesh structure of the metal electrode after sintering are silver and lead in a metallic state. This indicates that the addition of the functional adjustment layer changes the physical and chemical properties of the glass body, thereby forming a large number of uniformly distributed conductive metal particles in the glass mesh structure, which greatly improves the conductive properties of the glass body.

[0113] Comparative Example 1

[0114] This comparative example provides a method for preparing a conventional Topcon battery, and the steps are as follows:

[0115] Step A: Select a silicon substrate. Select a single crystal n-type silicon wafer with a bulk resistivity of 2.5Ω•cm.

[0116] Step B, texturing the surface of the silicon substrate: A sodium hydroxide alkaline solution with a mass fraction of 4% was used to anisotropically etch the single crystal n-type silicon wafer to obtain a textured single crystal n-type silicon wafer surface with a reflectivity of 11.8%.

[0117] Step C: Prepare PN junction by high temperature diffusion on the surface of silicon substrate. Boron element is diffused on the single crystal n-type silicon wafer by high temperature diffusion process, and the sheet resistance after diffusion is 130.

[0118] Step D: Etching and cleaning the back surface of the silicon substrate: Use a wet single-side etching device to etch and remove the boron-doped area on the back side of the single-crystal n-type silicon wafer, while retaining the borosilicate glass layer on the front side.

[0119] Step E: growing a tunneling oxide layer and a poly silicon layer on the back surface. The tunneling oxide layer is grown by furnace tube thermal oxidation method. The thickness of the oxide layer is 1.8 nanometers. SiH4 gas is introduced into the furnace tube to prepare an 80 nanometer poly silicon layer.

[0120] Step F: using a high-temperature furnace tube to dope phosphorus into the back Poly silicon layer, wherein the concentration of active phosphorus in the Poly silicon layer reaches 4E20 atoms per cubic centimeter.

[0121] Step G: Use wet equipment to clean the Poly silicon layer plated on the front side, and remove the BSG layer (borosilicate glass layer) and PSG layer (phosphorus silicon glass layer) on the front and back sides.

[0122] Step H: depositing a 4-nanometer aluminum oxide film layer on the boron diffusion layer.

[0123] Step I: deposit a 78 nanometer silicon nitride film on the surface of the aluminum oxide film to form a passivation anti-reflection layer.

[0124] Step J: Conductive silver paste is placed on the front and back surfaces of the battery respectively, and a Topcon battery is prepared after drying and sintering.

[0125] Example 4

[0126] The various steps of Example 4 are basically the same as those of Comparative Example 1, except that a step of preparing a functional adjustment layer on the surface of the aluminum oxide film layer is added after step H of Comparative Example 1. Specifically, a mask is used to cover the area outside the electrode pattern, the electrode pattern is exposed, and a 5-nanometer functional adjustment layer is deposited (the functional adjustment layer is prepared on the surface of the aluminum oxide film layer by a PECVD method, the frequency of the RF power supply is 13.56 MHz, and the RF power range is 30 mW / cm^2; a mixed gas of TMAL, silane and nitrous oxide is used as a reaction precursor, and the flow ratio of TMA:SiH4:N2O is 1:1:8; the pressure of the reaction chamber is set to 100 Pa. A film layer containing aluminum, silicon and oxygen with a thickness of 5 nm is obtained, i.e., the functional adjustment layer, wherein aluminum ions and silicon ions are specific cations that can be released by the functional adjustment layer).

[0127] The performance of the Topcon solar cells prepared in Comparative Example 1 and Example 4 were tested respectively, and the results are shown in Table 1 below. Table 1 shows the values ​​of various parameters (short-circuit current (Isc), open-circuit voltage (Voc), fill factor (FF), battery conversion rate (Eta) and series resistance (Rs)) of the battery prepared in Example 4, taking the short-circuit current (Isc), open-circuit voltage (Voc), fill factor (FF), battery conversion rate (Eta) and series resistance (Rs) of Comparative Example 1 as the benchmark (100%). In other words, the values ​​given in Table 1 below are the changes in the parameters of Example 4 relative to the parameters of Comparative Example 1, based on the actual test results of Comparative Example 1 and the actual test results of Example 4, and taking the various parameters of Comparative Example 1 as the benchmark. It can be seen intuitively from Table 1 that the addition of a functional adjustment layer can improve the open-circuit voltage, fill factor and photoelectric conversion efficiency of the Topcon cell solar cell, and can effectively reduce the series resistance of the Topcon cell.

[0128]

[0129] The introduction provided in the above steps is only used to help understand the method, structure and core idea of ​​the present invention. For ordinary technicians in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also belong to the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a crystalline silicon solar cell, characterized in that: include: Step 1: Arranging a function adjustment layer (31) on the passivation dielectric layer and / or in the passivation dielectric layer; Step 2: Printing electrode paste (32) on the passivation dielectric layer and at a position corresponding to the function adjustment layer (31); Step 3: sintering to form a metal electrode (30); The function adjustment layer (31) comprises: at least one of compounds containing specific cations, and the compound containing specific cations can release the specific cations at a sintering temperature, and the specific cations are cations corresponding to elements involved in the glass network former.

2. The method for preparing a crystalline silicon solar cell according to claim 1, characterized in that: The specific cation is a cation of at least one of the following elements: germanium, gallium, silicon, lanthanum, aluminum and zirconium; or / and, The function adjustment layer (31) is a single-layer structure or a multi-layer stacked structure, and the total thickness of the function adjustment layer (31) is 1 nm to 20 nm.

3. The method for preparing a crystalline silicon solar cell according to claim 2, characterized in that: The compounds containing specific cations include: Ga2O3, GeO2, SiAl x O y Hereafter SiGe x Al y O z .

4. The method for preparing a crystalline silicon solar cell according to claim 1, characterized in that: There are a plurality of the function adjustment layers (31), the plurality of the function adjustment layers (31) are arranged at intervals, and the plurality of the function adjustment layers (31) correspond one-to-one to the plurality of the metal electrodes (30).

5. The method for preparing a crystalline silicon solar cell according to any one of claims 1 to 4, characterized in that: The orthographic projection of the printed electrode paste (32) on the passivation medium layer completely falls within the region of the function adjustment layer.

6. The method for preparing a crystalline silicon solar cell according to claim 1, characterized in that: The passivation dielectric layer is a single layer or stacked layer thin film formed by one or more of the following materials: Silicon nitride, silicon oxide, aluminum oxide and aluminum oxynitride.

7. The method for preparing a crystalline silicon solar cell according to any one of claims 1 to 4 and 6, characterized in that: The crystalline silicon solar cell is a Topcon solar cell, and the method further includes the following steps before step 1: A first type doped layer is formed on the light-receiving surface of the silicon substrate, a tunneling oxide layer and a second type doped polysilicon layer are sequentially prepared on the backlight surface of the silicon substrate, and then the passivation dielectric layer is respectively prepared on the first type doped layer and the second type doped polysilicon layer.

8. The method for preparing a crystalline silicon solar cell according to claim 7, characterized in that: The function adjustment layer is arranged on the passivation medium layer of the light-receiving surface of the Topcon solar cell or / and in the passivation medium layer.

9. The method for preparing a crystalline silicon solar cell according to any one of claims 1 to 4 and 6, characterized in that: The crystalline silicon solar cell is a BC solar cell, and before step 1, the following steps are also included: Prepare n-type regions and p-type regions that are alternately distributed on the backlight surface of the silicon substrate, and prepare passivation dielectric layers on the surface of the n-type region, the surface of the p-type region, and the surface of the silicon substrate between the n-type region and the p-type region; The n-type region includes a first tunneling oxide layer arranged on the backlight side of the silicon substrate, and an n-type doped silicon layer arranged on the first tunneling oxide layer; the p-type region includes a second tunneling oxide layer arranged on the backlight side of the silicon substrate, and a p-type doped silicon layer arranged on the second tunneling oxide layer.

10. The method for preparing a crystalline silicon solar cell according to claim 9, characterized in that: The function adjustment layer is arranged on the passivation dielectric layer corresponding to the n-type region or / and in the passivation dielectric layer; the function adjustment layer is arranged on the passivation dielectric layer corresponding to the p-type region or / and in the passivation dielectric layer.

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