Preparation method of solar cell and photovoltaic module

Abstract

The invention discloses a preparation method of a solar cell and a photovoltaic module, and the preparation method of the solar cell comprises the following steps: preparing a dielectric layer and a doping layer on the surface of a silicon substrate, the thickness of the doping layer being 30-90 nm; preparing a first aluminum oxide layer on one side, deviating from the silicon substrate, of the doping layer; the first electrode is prepared, specifically, electrode paste is printed, and the electrode paste comprises conductive metal powder, glass powder and an organic carrier; sintering treatment, including laser-induced sintering, so that the first electrode passes through the first aluminum oxide layer and is in contact with the doping layer; the glass powder is prepared from the following components in percentage by mass: 7.5 percent to 30 percent of SiO2, 10 percent to 35 percent of B2O3, 1 percent to 12 percent of ZnO, 5 percent to 30 percent of BaO, 5 percent to 35 percent of PbO, 0.5 percent to 4 percent of GeO2, 0.5 percent to 8.5 percent of TiO2 and 0.5 percent to 3.5 percent of NaF.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solar cells, and in particular to a preparation method of a solar cell and a photovoltaic module. BACKGROUND

[0002] The passivation contact structure is arranged in the solar cell, which can effectively reduce the recombination loss of the carriers at the electrode-silicon substrate interface, and reduce the surface defect state density of the silicon substrate. However, the doping layer of the passivation contact structure contains doped polysilicon material, which has high optical parasitic absorption, which limits the further improvement of the photoelectric conversion efficiency of the solar cell. SUMMARY

[0003] In order to better improve the photoelectric conversion efficiency of the solar cell, the present application discloses a preparation method of a solar cell and a photovoltaic module.

[0004] In a first aspect, the present application provides a preparation method of a solar cell.

[0005] The preparation method of the solar cell comprises the following steps:

[0006] A medium layer and a doping layer are prepared on the surface of the silicon substrate, and the thickness of the doping layer is 30nm-90nm;

[0007] A first aluminum oxide layer is prepared on the side of the doping layer away from the silicon substrate;

[0008] A first electrode is prepared, comprising:

[0009] Printing electrode paste, the electrode paste comprising conductive metal powder, glass powder and organic carrier;

[0010] Sintering treatment, the sintering treatment comprising laser-induced sintering, so that the first electrode passes through the first aluminum oxide layer and forms contact with the doping layer;

[0011] The glass powder comprises the following components by mass percentage:

[0012]

[0013]

[0014] As an optional implementation, in the embodiments of the present application, the mass ratio of PbO to GeO2 is (8:1)-(15:1).

[0015] As an optional implementation, in the embodiments of the present application, the glass powder further comprises Li2O with a mass percentage of 0.1%-3.5%.

[0016] As an optional implementation, in the embodiment of the present application, the thickness of the first aluminum oxide layer is 0.5 nm to 2.9 nm.

[0017] As an optional implementation, in the embodiment of the present application, the mass ratio of the conductive metal powder, the glass powder and the organic carrier is (75% to 90%):(0.5% to 4.5%):(5% to 15%).

[0018] (5% to 15%).

[0019] As an optional implementation, in the embodiment of the present application, the conductive metal powder comprises one or more of silver, copper, aluminum or zinc.

[0020] As an optional implementation, in the embodiment of the present application, the doped layer comprises a first doped polysilicon layer, a first silicon oxide layer and a second doped polysilicon layer which are sequentially stacked on the surface of the dielectric layer;

[0021] The surface doping concentration of the doping element in the second doped polysilicon layer is greater than the surface doping concentration of the doping element in the first doped polysilicon layer.

[0022] The first electrode is in contact with the second doped polysilicon layer.

[0023] As an optional implementation, in the embodiment of the present application, the thickness of the first doped polysilicon layer is 5 nm to 18 nm, the thickness of the first silicon oxide layer is 2 nm to 10 nm, and the thickness of the second doped polysilicon layer is 10 nm to 75 nm.

[0024] As an optional implementation, in the embodiment of the present application, the surface doping concentration of the doping element in the first doped polysilicon layer is 1×10 19 / cm 3 to 5×10 21 / cm 3 .

[0025] The surface doping concentration of the doping element in the second doped polysilicon layer is 2×10 20 / cm 3 to 9×10 21 / cm 3 .

[0026] As an optional implementation, in the embodiment of the present application, the dielectric layer, the doped layer, the first aluminum oxide layer and the first electrode are located on the back light side of the silicon substrate.

[0027] A first passivation layer is further formed on the side of the first alumina layer away from the silicon substrate. The first passivation layer includes one or more combinations of a first silicon nitride layer, a first silicon oxynitride layer, or a second silicon oxide layer.

[0028] The silicon substrate has a first diffusion layer on the light-receiving side and a second passivation layer disposed on the side of the first diffusion layer away from the silicon substrate. The second passivation layer includes one or more of the following: a second aluminum oxide layer, a second silicon nitride layer, a second silicon oxynitride layer, or a third silicon oxide layer.

[0029] The silicon substrate also has a second electrode on one side of the light-receiving surface, and the second electrode passes through the second passivation layer and forms contact with the first diffusion layer.

[0030] As an optional implementation, in the embodiments of this application, the sintering process includes sequentially performing low-temperature sintering and laser-induced sintering, wherein the sintering temperature of the low-temperature sintering is lower than the peak sintering temperature of the electrode slurry.

[0031] As an optional implementation, in the embodiments of this application, the sintering temperature of the low-temperature sintering is 500℃~650℃.

[0032] And / or,

[0033] The laser power density of the laser-induced sintering treatment is 40 kW / cm². 2 ~55kW / cm 2 The pulse width is 10ns to 200ns, the spot diameter is 0.8μm to 1.5μm, and the scanning speed is 4m / s to 7m / s.

[0034] As an optional implementation, in the embodiments of this application, a light injection process is performed before the laser-induced sintering step;

[0035] or,

[0036] After the laser-induced sintering step, light injection processing is performed.

[0037] Secondly, embodiments of this application provide a photovoltaic module.

[0038] A photovoltaic module comprising a solar cell prepared by the method described in the first aspect.

[0039] Compared with the prior art, the beneficial effects of this application are as follows:

[0040] The application introduces a first aluminum oxide layer on the side of the doped layer away from the silicon substrate, uses a low-corrosion electrode paste containing specific glass powder components as the paste for preparing the first electrode, and matches a specific sintering process. Specifically, by adding glass powder containing specific proportions of PbO and GeO2 in the electrode paste, the thermal expansion coefficient and corrosion characteristics of the electrode paste are effectively controlled, and the corrosion of the electrode paste is effectively reduced. Among them, PbO can etch the aluminum oxide layer, but also causes excessive ablation of the doped layer with thickness reduction by the electrode paste. Based on the control of the amount of PbO, a certain amount of GeO2 is added. The introduction of GeO2 not only reduces the lateral flowability of the electrode paste at high temperature, but also alleviates the corrosion of PbO, effectively reducing the overall corrosion ability of the paste, thereby significantly reducing the risk of excessive ablation of the doped layer. At the same time, the first aluminum oxide layer acts as a physical barrier to prevent the electrode paste from directly contacting and corroding the doped layer too early.

[0041] During the sintering process of the first electrode, a laser-induced sintering process is used, which can accurately control the ablation process by using the controllable characteristics of laser energy, to ensure that the low-corrosion electrode paste can burn through the first aluminum oxide layer, so that the first electrode and the doped layer form reliable electrical contact. At the same time, the low-corrosion electrode paste used in the application has better controllability, which can avoid excessive ablation or burning of the thinned doped layer during the ablation process. In summary, through the synergistic effect of the first aluminum oxide layer, the low-corrosion electrode paste and the laser-induced sintering process, the thinned doped layer can not only maintain good passivation effect, but also realize reliable electrical contact with the electrode, and finally achieve significant improvement of photoelectric conversion efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings used in the embodiments will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0043] Figure 1 is a preparation flowchart of a solar cell disclosed by the embodiments of the present application;

[0044] Figure 2 is a structure schematic diagram of a solar cell disclosed by the embodiments of the present application;

[0045] Figure 3 is a structure schematic diagram of another solar cell disclosed by the embodiments of the present application.

[0046] Icon: 1, silicon substrate; 11, first diffusion layer; 12, second diffusion layer; 2, dielectric layer; 3, doped layer; 31, first doped polysilicon layer; 32, first silicon oxide layer; 33, second doped polysilicon layer; 4, first aluminum oxide layer; 5, first electrode; 6, first passivation layer; 61, first silicon nitride layer; 7, second passivation layer; 71, second aluminum oxide layer; 72, second silicon nitride layer; 8, second electrode. DETAILED DESCRIPTION

[0047] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0048] In the present application, the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal", etc. are based on the orientations or positional relationships shown in the drawings. These terms are mainly used for better description of the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0049] In addition, in addition to being used to indicate the orientations or positional relationships, the above-mentioned partial terms can also be used to indicate other meanings, for example, the term "upper" can also be used to indicate a certain dependent relationship or connection relationship in some cases. Those of ordinary skill in the art can understand the specific meanings of these terms in the present application according to the specific circumstances.

[0050] In addition, the terms "mount", "set", "provided with", "connect", "connected" should be broadly understood. For example, it can be fixedly connected, detachably connected, or integrally constructed; it can be mechanically connected, or electrically connected; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication between two devices, elements or components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present application according to the specific circumstances.

[0051] In addition, the terms "first", "second", etc. are mainly used to distinguish different devices, elements or components (the specific types and structures can be the same or different), and are not used to indicate or imply the relative importance and quantity of the indicated devices, elements or components. Unless otherwise stated, the meaning of "multiple" is two or more.

[0052] Although the optical parasitic absorption can be reduced by reducing the thickness of the doped layer, the doped layer with a too small thickness is prone to be burnt through during the high-temperature sintering process when the electrode is produced by using the conventional electrode paste. When the burning through occurs, the dielectric layer under the doped layer is thin and is directly exposed to damage, which leads to a significant increase in the non-radiative recombination on the surface of the silicon substrate, and thus results in a decrease in the open-circuit voltage and the fill factor of the solar cell, and finally affects the overall conversion efficiency.

[0053] The inventor has found through experiments that the introduction of the aluminum oxide layer can effectively prevent the electrode paste from burning through the doped layer. However, the aluminum oxide has excellent corrosion resistance, and the conventional electrode paste and high-temperature sintering process cannot burn through the aluminum oxide layer, which leads to that the electrode cannot form a good electrical contact with the doped layer. Further, although the electrode paste and laser-induced sintering process can burn through the aluminum oxide layer, the controllability of the sintering process is still poor, and the doped layer is still prone to be excessively ablated or burnt through during the sintering process.

[0054] To break through this technical bottleneck, the present application provides a preparation method of a solar cell and a photovoltaic module. The technical solutions of the present application will be further described below in combination with embodiments and drawings.

[0055] In a first aspect, referring to Figure 1 The embodiments of the present application provide a preparation method of a solar cell with a structure as shown in Figure 2 The preparation method comprises the following steps:

[0056] A dielectric layer 2 and a doped layer 3 are prepared on the surface of a silicon substrate 1, and the thickness of the doped layer 3 is 30 nm to 90 nm;

[0057] A first aluminum oxide layer 4 is prepared on the side of the doped layer 3 away from the silicon substrate 1;

[0058] A first electrode 5 is prepared, comprising:

[0059] The electrode paste comprises conductive metal powder, glass powder and an organic carrier;

[0060] A sintering process is performed, and the sintering process comprises laser-induced sintering, so that the first electrode 5 passes through the first aluminum oxide layer 4 and forms a contact with the doped layer 3;

[0061] The glass powder comprises the following components in mass percentage:

[0062]

[0063] The application introduces a first aluminum oxide layer 4 on the side of the doped layer 3 away from the silicon substrate 1, uses a low-corrosion electrode paste containing a specific glass powder composition as the paste for preparing the first electrode 5, and matches a specific sintering process. Specifically, by adding a glass powder containing a specific ratio of PbO and GeO2 in the electrode paste, the thermal expansion coefficient and corrosion characteristics of the electrode paste are effectively controlled, so that the corrosion of the electrode paste is effectively reduced. Among them, PbO can etch the aluminum oxide layer, but also make the electrode paste easily cause excessive ablation to the thickness-reduced doped layer 3. On the basis of reducing the amount of PbO as much as possible, a certain amount of GeO2 is added. The introduction of GeO2 not only reduces the lateral flowability of the electrode paste at high temperature, but also alleviates the corrosion of PbO, effectively reduces the overall corrosion ability of the paste, thereby significantly reducing the risk of excessive ablation to the doped layer 3. At the same time, the first aluminum oxide layer 4 acts as a physical barrier to prevent the electrode paste from directly contacting and corroding the doped layer 3 too early.

[0064] During the sintering process of the first electrode 5, the laser-induced sintering process is adopted, which can accurately control the ablation process by using the controllable characteristics of laser energy, so as to ensure that the low-corrosion electrode paste can burn through the first aluminum oxide layer 4, so that the first electrode 5 forms reliable electrical contact with the doped layer 3; at the same time, the low-corrosion electrode paste adopted by the application has better controllability, which can avoid excessive ablation or burning through of the thinned doped layer 3 during the ablation process. In summary, through the synergistic effect of the first aluminum oxide layer 4, the low-corrosion electrode paste and the laser-induced sintering process, the thinned doped layer 3 can not only maintain good passivation effect, but also realize reliable electrical contact with the electrode, so as to finally achieve significant improvement of photoelectric conversion efficiency.

[0065] In addition, in the glass powder formula, SiO2 is the main component of the glass powder, which has good chemical stability and thermal stability, can provide a basic skeleton structure for the glass powder, and can make the first electrode maintain a certain shape and strength during high-temperature sintering. B2O3 can reduce the softening temperature and viscosity of the glass powder, promote the flow of the glass powder during sintering, make the electrode paste better wet the surface of the doped layer 3, and help the silver paste form good contact with the doped layer 3. ZnO can react with other components during sintering to optimize the chemical stability, thermal stability and electrical properties of the glass powder. BaO helps the electrode paste form a good conductive network to reduce the contact resistance. PbO can significantly reduce the melting point and viscosity of the glass powder, improve the electrical conductivity and chemical stability of the electrode paste. TiO2 can act as a crystallization core during sintering, promote the uniform precipitation of metal (such as silver) microcrystals at the metal-semiconductor interface, thereby reducing the contact resistance and improving the electrical conductivity, and also can strengthen the contact performance of the first electrode 5 and the doped layer 3 through the microcrystallization interface glass phase. The fluorine ion (F -) has high reactivity, can corrode the surface of the doped layer 3 in the sintering process, and the silicon nitride (SiN x ) layer, etc. The first passivation layer 6 (specifically described later) promotes the first electrode 5 and the doped layer 3 to form a more intimate ohmic contact, thereby reducing the contact resistance.

[0066] Exemplarily, the amount of SiO2 in the glass powder can be 7.5%, 11.5%, 20%, or 30% by mass percentage; the amount of B2O3 can be 10%, 15%, 25%, or 35%; the amount of ZnO can be 1%, 5%, 8%, or 12%; the amount of BaO can be 5%, 15%, or 30%; the amount of PbO can be 5%, 15%, 25%, 35%; the amount of GeO2 can be 0.5%, 2%, 3%, 4%; the amount of TiO2 can be 0.5%, 5.5%, and 8.5%; the amount of NaF can be 0.5%, 1.5%, or 3.5%, etc.

[0067] In some embodiments, the mass ratio of PbO to GeO2 in the glass powder is (8:1) to (15:1).

[0068] By controlling the ratio of PbO and GeO2 within the above range, GeO2 can fully play a role in inhibiting the corrosion of PbO, and better inhibit the lateral flow of the electrode paste, reduce the lateral corrosion area, and further enhance the controllability of the electrode paste in the sintering process. If the amount of GeO2 is too low, the risk of excessive ablation of the doped layer 3 increases. If the amount of GeO2 is too high, PbO is excessively weakened, which is not conducive to the electrode paste passing through the first aluminum oxide layer 4 and the doped layer 3 to form a better contact, and the contact resistance of the electrode is high. Exemplarily, the mass ratio of PbO to GeO2 is (8:1), (10:1), (15:1), etc.

[0069] In some embodiments, the glass powder further includes 0.1% to 3.5% of Li2O by mass percentage.

[0070] Li + has a small radius and high stability, and does not react while filling the network gap of the glass system. Therefore, Li + can achieve the effect of stably reducing the glass transition temperature, and the low glass transition temperature makes the electrode paste have good wettability in the sintering process.

[0071] The surface of the first aluminum oxide layer 4 is usually provided with a first passivation layer 6 such as a first silicon nitride layer 61. The wettability of the electrode paste is enhanced, the ablation of the first passivation layer 6 by the electrode paste at a lower sintering temperature is enhanced, the first passivation layer 6 is burned through before laser-induced sintering, the energy generated by laser-induced sintering can better act on the first aluminum oxide layer 4, and the electrode paste can burn through the first aluminum oxide layer 4 and form a better electrical contact with the doped layer 3.

[0072] For example, the amount of Li2O in the glass powder can be 0.1%, 2.5%, or 3.5% by mass.

[0073] In some embodiments, the thickness of the first aluminum oxide layer 4 is 0.5 nm to 2.9 nm.

[0074] Under the action of laser-induced sintering, the low-corrosion electrode paste can penetrate the first aluminum oxide layer 4 with this thickness, so that the first electrode 5 forms a better electrical contact with the doped layer 3. When the thickness of the first aluminum oxide layer 4 is too low, the passivation effect of the first aluminum oxide layer 4 is poor, and the electrode paste is prone to excessive ablation of the doped layer 3 during sintering. When the thickness of the first aluminum oxide layer 4 is too high, the low-corrosion paste burn-through effect is poor, which is not conducive to forming a good contact with the first electrode 5, resulting in a decrease in the photoelectric conversion efficiency of the solar cell.

[0075] For example, the thickness of the first aluminum oxide layer 4 can be 0.5 nm, 1.5 nm, or 2.9 nm.

[0076] In some embodiments, the mass ratio of the conductive metal powder, the glass powder, and the organic carrier is (75% to 90%):(0.5% to 4.5%):(5% to 15%). The components are used in this ratio, the conductive metal powder and the glass powder are fully mixed, which is more conducive to fully exerting the regulating effect of the glass powder on the overall corrosion performance of the electrode paste, and forming an electrode paste with low corrosion.

[0077] In the electrode paste, the conductive metal powder mainly plays a role in forming a conductive network / path. The organic carrier mainly plays a role in dispersing the conductive metal powder and the glass powder, and providing wettability. In this application, as long as the selected conductive metal powder can achieve its conductive function and the organic carrier can achieve its dispersion and wetting function, the specific types of the conductive metal powder and the organic carrier are not limited.

[0078] Exemplarily, the conductive metal powder comprises one or more of silver, copper, aluminum or zinc. The organic carrier can be composed of 0.1% to 0.8% binder, 0.2% to 0.9% silicone oil, 0.2% to 2.1% elastomer, 0% to 0.8% auxiliary agent, 2% to 8.5% solvent and 1% to 7.5% plasticizer. Through the joint action of various components, the conductive metal powder and glass powder can be better dispersed and wetted. Among them, the binder can be ethyl cellulose, polyvinyl butyral, acrylic resin, nitrocellulose, etc. The silicone oil is polydimethylsiloxane. The elastomer can be a thermoplastic elastomer, such as styrene-butadiene-styrene block copolymer, styrene-isoprene-styrene block copolymer. The auxiliary agent can be a silane coupling agent (such as γ-aminopropyl triethoxysilane KH550); the solvent can be diethylene glycol monobutyl ether, diethylene glycol dimethyl ether or terpineol, etc. The plasticizer can be phthalate, such as dibutyl phthalate, or fatty acid ester, such as dibutyl sebacate, etc.

[0079] In some embodiments, with reference to Figure 3 , the doped layer 3 comprises a first doped polysilicon layer 31, a first silicon oxide layer 32 and a second doped polysilicon layer 33 sequentially stacked on the surface of the dielectric layer 2;

[0080] The surface doping concentration of the doping element in the second doped polysilicon layer 33 is greater than the surface doping concentration of the doping element in the first doped polysilicon layer 31.

[0081] The first electrode 5 is in contact with the second doped polysilicon layer 33.

[0082] The second doped polysilicon layer 33 is rich in doping elements, which reduces the contact resistance with the first electrode 5 and improves the carrier transport efficiency. The first silicon oxide layer 32 arranged between the first doped polysilicon layer 31 and the second doped polysilicon layer 33 acts as a barrier layer to block the diffusion of the doping elements (such as phosphorus) in the second doped polysilicon layer 33 to the side where the first doped polysilicon layer 31 is located, so as to make the doping elements rich in the second doped polysilicon layer 33 and better improve the surface doping concentration of the doping elements in the second doped polysilicon layer 33.

[0083] During the crystallization annealing process for preparing the doped layer 3, part of the doping elements is prone to diffuse from the second doped polysilicon layer 33 to the side of the silicon substrate 1. The first doped polysilicon layer 31 can act as a buffer layer to reduce the risk of the doping elements penetrating the dielectric layer 2 and causing the film to burst. After the crystallization annealing, a small amount of doping elements enter the interface of the silicon substrate 1 through the dielectric layer 2, and form a second diffusion layer 12 on the surface of the silicon substrate 1 close to the dielectric layer 2.

[0084] Further, the thickness of the first doped polysilicon layer 31 is 3-15 nm, the thickness of the first silicon oxide layer 32 is 2-10 nm, and the thickness of the second doped polysilicon layer 33 is 10-87 nm.

[0085] The thickness of the first doped polysilicon layer 31 is 3-15 nm, which can effectively buffer and avoid the increase of optical parasitic absorption caused by excessive thickness. If the thickness of the first doped polysilicon layer 31 is too thin, the buffer effect of the first doped layer 3 is poor, and the risk of film explosion caused by the penetration of the doping element into the dielectric layer 2 is high.

[0086] The thickness of the first silicon oxide layer 32 is 2-10 nm, which can better regulate the diffusion of the doping element under the annealing condition, and can improve the surface doping concentration of the doping element in the second doped polysilicon layer 33 while reducing the risk of film explosion.

[0087] For example, the thickness of the first doped polysilicon layer 31 can be 3 nm, 5 nm, or 15 nm, the thickness of the first silicon oxide layer 32 can be 2 nm, 4 nm, 6 nm, 8 nm, or 10 nm, and the thickness of the second doped polysilicon layer 33 can be 10 nm, 20 nm, 40 nm, or 87 nm.

[0088] The thickness of the second doped polysilicon layer 33 is 10-87 nm, which can ensure good contact with the first electrode 5 and meet the requirement of low contact resistance. At the same time, the optical performance is also considered to avoid the increase of optical parasitic absorption caused by excessive thickness.

[0089] In some embodiments, the surface doping concentration of the doping element in the first doped polysilicon layer 31 is 1×10 19 / cm 3 -5×10 21 / cm 3 .

[0090] The surface doping concentration of the doping element in the second doped polysilicon layer 33 is 2×10 20 / cm 3 -9×10 21 / cm 3 .

[0091] The surface doping concentration of the doping element in the second doped polysilicon layer 33 and the first doped polysilicon layer 31 is within the above-mentioned concentration range, which not only facilitates the carrier transmission, but also significantly improves the contact performance of the electrode paste and the second doped polysilicon layer 33. For example, the surface doping concentration of the doping element in the first doped polysilicon layer 31 can be 1×10 19 / cm 3 , 7×10 19 / cm 32 x 10 20 / cm 3 8 x 10 20 / cm 3 5 x 10 21 / cm 3 etc. In the second doped polysilicon layer 33, the surface doping concentration of the doping element can be 2 x 10 20 / cm 3 6 x 10 20 / cm 3 9 x 10 20 / cm 3 2 x 10 21 / cm 3 9 x 10 21 / cm 3 etc.

[0092] Further, the material of the dielectric layer 2 can include a plurality of dielectric materials, such as at least one of silicon oxide, magnesium fluoride, amorphous silicon, polysilicon, silicon carbide, silicon nitride, silicon oxynitride, aluminum oxide, or titanium oxide. In particular, the dielectric layer 2 can be composed of a silicon oxide layer containing silicon oxide. This is because the silicon oxide layer has excellent passivation performance and can minimize the loss of recombination of minority carriers on the surface of the semiconductor substrate. In order to better provide interface passivation for the substrate, the thickness of the dielectric can be 0.1 nm to 5 nm. For example, the thickness of the dielectric layer 2 can be 0.1 nm, 0.5 nm, 1 nm, 1.5 nm, 2 nm, 3 nm, 4 nm, etc.

[0093] Further, the medium layer 2 and the doped layer 3 are prepared by plasma chemical vapor deposition. The reaction time for preparing the medium layer 2 is 50-120 s, the N2O flow rate is 7000-15000 sccm, the power is 11000-16000 W, and the power frequency is 70-150 Hz. The first doped polysilicon layer 31 and the second doped polysilicon layer 33 are prepared by first preparing a first doped amorphous silicon layer and a second doped amorphous silicon layer, and then performing crystallization annealing. The reaction time for preparing the first doped amorphous silicon layer is 10-40 s, the PH3 flow rate is 170-500 sccm, the SiH4 flow rate is 1500-4000 sccm, the power is 11500-15000 W, and the power frequency is 160-220 Hz; the reaction time for preparing the first silicon oxide layer 32 is 10-35 s, the N2O flow rate is 7000-15000 sccm, the power is 7000-12500 W, and the power frequency is 170-270 Hz; the reaction time for preparing the second doped amorphous silicon layer is 250-600 s, the PH3 flow rate is 170-500 sccm, the SiH4 flow rate is 1500-4000 sccm, the power is 11500-15000 W, and the power frequency is 160-220 Hz; the reaction time for preparing the SiO2 is 30-75 s, the SiH4 flow rate is 1500-2500 sccm, the N2O flow rate is 7500-10000 sccm, the power is 10500-16000 W, and the power frequency is 170-270 Hz; and the crystallization annealing temperature is 880-920 °C.

[0094] In some embodiments, referring to Figure 3 , the medium layer 2, the doped layer 3, the first aluminum oxide layer 4, and the first electrode 5 are located on the back light side of the silicon substrate 1;

[0095] The first aluminum oxide layer 4 further has a first passivation layer 6 on the side away from the silicon substrate 1, and the first passivation layer 6 comprises one or a combination of the first silicon nitride layer 61, the first silicon oxynitride layer, and the second silicon oxide layer;

[0096] The light-receiving side of the silicon substrate 1 has a first diffusion layer 11, and a second passivation layer 7 disposed on the side of the first diffusion layer 11 away from the silicon substrate 1, and the second passivation layer 7 comprises one or a combination of the second aluminum oxide layer 71, the second silicon nitride layer 72, the second silicon oxynitride layer, and the third silicon oxide layer;

[0097] The light-receiving side of the silicon substrate 1 further has a second electrode 8, and the second electrode 8 forms contact with the first diffusion layer 11 through the second passivation layer 7.

[0098] Exemplarily, as Figure 3As shown, the first passivation layer 6 is a first silicon nitride layer 61, and the second passivation layer 7 is a second aluminum oxide layer 71 and a second silicon nitride layer 72 arranged in sequence.

[0099] The first diffusion layer 11 is formed by diffusing a doping element from the surface of the silicon substrate 1. For example, boron diffusion treatment is performed on the silicon substrate 1 to form a boron diffusion layer on the surface of the silicon substrate 1. The doping element of the first diffusion layer 11 is of an opposite conductivity type to that of the second diffusion layer 12. For example, when the doping element of the first diffusion layer 11 is a P-type conductive doping element (e.g., boron), the doping element of the second diffusion layer 12 is an N-type conductive doping element (e.g., phosphorus).

[0100] The first aluminum oxide layer 4 and the first passivation layer 6 form a composite passivation system for the back surface to maximize the reduction of interface recombination. In addition, unlike the first passivation layer 6 which mainly serves to provide passivation, the first aluminum oxide layer 4, in addition to providing passivation, cooperates with a low-etching electrode paste and a laser-induced sintering process to jointly regulate the ablation process of the first electrode 5, thereby facilitating the first electrode 5 to form a more excellent contact with the second doped polysilicon layer 33, effectively reducing the contact resistance of the first electrode 5, and significantly reducing the risk of excessive ablation or even burning through the doped layer 3 of the first electrode 5, and ultimately improving product yield.

[0101] The second passivation layer 7 is arranged on the light-receiving surface to simultaneously improve the passivation effect of the light-receiving surface and promote the improvement of the photoelectric conversion efficiency of the solar cell.

[0102] The preparation method of the second electrode 8 is not specifically limited in the present application. For example, the second electrode 8 can be prepared by screen printing: after a commercially available electrode paste is printed onto the metallized area for preparing the second electrode 8, drying and sintering treatment is performed, wherein the sintering can be high-temperature sintering or laser-induced sintering.

[0103] In some embodiments, the sintering treatment includes sequentially performing low-temperature sintering and laser-induced sintering, and the sintering temperature of the low-temperature sintering is less than the peak sintering temperature of the electrode paste.

[0104] After the printing of the electrode paste is completed, low-temperature sintering treatment is performed first. The low-temperature sintering treatment can volatilize the organic carrier in the electrode paste by heat, and also can soften the glass powder to enhance the wettability of the electrode paste, so that the electrode paste forms a better ablation effect on the first passivation layer 6 located on the surface of the first aluminum oxide layer 4 before laser-induced sintering, which is beneficial to the ablation process of the first aluminum oxide layer 4 acted by the energy generated by the subsequent laser-induced sintering.

[0105] Further, the sintering temperature of the low-temperature sintering is 500-650°C.

[0106] The thickness of the first aluminum oxide layer 4 is thin, and if the sintering temperature is too high, a large amount of H elements in the first passivation layer 6 and the first aluminum oxide layer 4 will begin to diffuse rapidly, penetrate the first aluminum oxide layer 4, and gather and combine to form hydrogen gas at the interface of the silicon substrate 1. As the hydrogen gas continues to accumulate, the gas pressure gradually increases, and when it exceeds the bonding force between the dielectric layer 2 and the silicon substrate 1, it will cause the dielectric layer 2 to partially delaminate and form a burst film. The above-mentioned low-temperature sintering treatment combined with the laser-induced sintering treatment effectively reduces the risk of burst film of the first aluminum oxide layer 4 during sintering, and improves the stability of the first aluminum oxide layer 4. For example, the sintering temperature of the low-temperature sintering can be 500°C, 550°C, 580°C, or 650°C, etc.

[0107] In some embodiments, the laser power density of the laser-induced sintering treatment is 40kW / cm 2 ~55kW / cm 2 , the pulse width is 10ns~200ns, and the spot diameter is 0.8μm~1.5μm, and the scanning speed is 4m / s~7m / s.

[0108] Controlling the energy of laser sintering within the above range can better ensure that the first aluminum oxide layer 4 with a burn-through thickness of 0.5nm~2.9nm is formed and good electrical contact is formed with the second doped polysilicon layer 33. For example, in the laser-induced sintering, the laser power density can be 40kW / cm 2 , 46kW / cm 2 , 52kW / cm 2 or 55kW / cm 2 , etc., the pulse width can be 10ns, 50ns, 100ns, or 200ns, etc., the spot diameter can be 0.8μm, 1μm, or 1.5μm, etc., and the scanning speed can be 4m / s, 6m / s, or 7m / s, etc.

[0109] In some embodiments, before the laser-induced sintering step, a light injection treatment is performed;

[0110] or,

[0111] After the laser-induced sintering step, a light injection treatment is performed.

[0112] The light injection can promote the diffusion of hydrogen elements from the first passivation layer 6 to the recombination centers with high defect density, reduce the interface defects, and improve the passivation effect.

[0113] Further, the light injection uses one-time heating accompanied by light, the peak temperature of the one-time heating is 500°C~650°C, the wavelength of the light is 300nm~2500nm, and the irradiation amplitude is 800W / m2~1200W / m 2And the light source can be a halogen lamp tube with a continuous spectrum of 300nm-2500nm. By controlling the process conditions of the light injection within the above range, sufficient energy can be provided for the diffusion of hydrogen elements, and the passivation effect can be better improved.

[0114] In a second aspect, the embodiments of the present application provide a photovoltaic module.

[0115] A photovoltaic module comprising the solar cell prepared by the method as mentioned in the first aspect.

[0116] The technical solutions of the present application will be further described below in combination with more specific embodiments.

[0117] Embodiment one

[0118] The embodiments of the present application provide a method for preparing a solar cell, comprising the following steps:

[0119] An N-type monocrystalline silicon wafer is provided, and the light-receiving surface of the N-type monocrystalline silicon wafer has a P-type first diffusion layer with a doping element of boron, and the back surface has an N-type second diffusion layer with a doping element of phosphorus;

[0120] A silicon oxide dielectric layer with a thickness of 2nm, a first phosphorus-doped amorphous silicon layer with a thickness of 10nm, a first silicon oxide layer with a thickness of 5nm, a second phosphorus-doped amorphous silicon layer with a thickness of 30nm, and a silicon oxide mask layer with a thickness of 10nm are sequentially prepared on the back surface of the N-type monocrystalline silicon wafer by using a plasma-enhanced chemical vapor deposition method, and then a crystallization annealing treatment is performed at 900℃, the first phosphorus-doped amorphous silicon layer is converted into a first phosphorus-doped polycrystalline silicon layer, and the second phosphorus-doped amorphous silicon layer is converted into a second phosphorus-doped polycrystalline silicon layer, and then the plating layer and the silicon oxide mask on the light-receiving surface are removed by RCA cleaning;

[0121] A second passivation layer composed of a second aluminum oxide layer and a second silicon nitride layer is sequentially prepared on the light-receiving surface of the N-type monocrystalline silicon wafer, comprising:

[0122] The second aluminum oxide layer with a thickness of 5nm is prepared by using an atomic layer deposition method;

[0123] The second silicon nitride layer with a thickness of 70nm is prepared by using a plasma-enhanced chemical vapor deposition method;

[0124] The first aluminum oxide layer with a thickness of 2nm is prepared on the surface of the second phosphorus-doped polycrystalline silicon layer away from the N-type monocrystalline silicon wafer by using an atomic layer deposition method;

[0125] The first silicon nitride layer with a thickness of 100nm is prepared on the surface of the first aluminum oxide layer away from the N-type monocrystalline silicon wafer;

[0126] The first electrode is prepared, comprising the following steps:

[0127] The first silicon nitride layer adopts a screen printing electrode paste, and the electrode paste is prepared by mixing glass powder, nano silver powder and an organic carrier according to a mass percentage of 3%:87%:10%. The glass powder contains 26.5% of SiO2, 2% of LiO, 20% of B2O3, 6% of ZnO, 17% of BaO, 20% of PbO, 2% of GeO2, 4.5% of TiO2 and 2% of NaF. The organic carrier contains 0.5% of ethyl cellulose, 0.6% of silicone oil (polydimethylsiloxane), 1% of styrene-butadiene-styrene block copolymer, 0.3% of γ-aminopropyl triethoxysilane, 4.6% of diethylene glycol monobutyl ether and 3% of dibutyl phthalate;

[0128] Low-temperature sintering: sintering at 600℃ for 1min to form an electrode precursor;

[0129] Laser-induced sintering: laser-induced sintering of the electrode precursor under the condition of a laser power density of 50kW / cm 2 , a pulse width of 100ns, a spot diameter of 1μm and a scanning speed of 5m / s to form a contact between the first electrode and the second doped polysilicon layer;

[0130] Light injection: heating the electrode precursor by using a one-time heating method with a peak temperature of 500℃, and performing light injection by using light with a wavelength of 300nm-2500nm and an irradiation amplitude of 800W / m 2 -1200W / m 2 ;

[0131] Preparation of the second electrode to form a contact between the second electrode and the P-type first diffusion layer.

[0132] Example Two

[0133] The embodiment of the application provides a preparation method of a solar cell, which is different from the embodiment one in that the mass ratio of PbO to GeO2 is 21:1, specifically, the mass percentage of PbO is 21%, the mass percentage of GeO2 is 1%, and the rest is consistent with the embodiment one.

[0134] Example Three

[0135] The embodiment of the application provides a preparation method of a solar cell, which is different from the embodiment one in that the mass ratio of PbO to GeO2 is 5.3:1, specifically, the mass percentage of PbO is 18.5%, the mass percentage of GeO2 is 3.5%, and the rest is consistent with the embodiment one.

[0136] Comparative Example One

[0137] The embodiment of the application provides a preparation method of a solar cell, which is different from the embodiment one in that the mass percentage of SiO2 in the glass powder formula is increased from 28.5% to 30.5%, that is, the SiO2 replaces the GeO2 with a mass percentage of 2%, and the rest is consistent with the embodiment one.

[0138] Comparative example two

[0139] The embodiment of the application provides a preparation method of a solar cell, which is different from the embodiment one in that the mass percentage of SiO2 in the glass powder formula is increased from 28.5% to 30.5%, that is, the SiO2 replaces the GeO2 with a mass percentage of 2%, and the rest is consistent with the embodiment one.

[0140] Comparative example three

[0141] The embodiment of the application provides a preparation method of a solar cell, which is different from the embodiment one in that in the step of preparing the first electrode, the laser-induced sintering is not used, but the high-temperature sintering at 800 DEG C for 1 min is used, and the rest is consistent with the embodiment one.

[0142] Experiment

[0143] The performance of the solar cell is tested by using a Wavelabs solar light simulator, and the test conditions are as follows: AM1.5, 1000 W / m 2 , and the test environment temperature is 25 DEG C. Before the test, the standard silicon cell is used to correct the solar light intensity simulated by the light source. The open-circuit voltage (Voc), short-circuit current (Jsc), fill factor (FF) and photoelectric conversion efficiency (PCE) test values of the corresponding perovskite solar cell are recorded.

[0144] The test results of the above embodiments and comparative examples are shown in Table 1.

[0145] Table 1

[0146] Voc (V) Jsc(mA / cm 2 )]]> FF (%) PCE (%) Example 1 0.7384 18.578 87.19 27.122 Example 2 0.7379 18.580 86.94 27.033 Example 3 0.7380 18.574 87.04 27.076 Comparative Example 1 0.7373 18.576 86.65 26.889 Comparative Example 2 0.7378 18.570 86.69 26.936 Comparative Example 3 0.7190 18.506 82.95 25.034

[0147] As can be seen from the comparison of the data of the embodiment one and the comparative example one in Table 1, the open-circuit voltage and the fill factor of the embodiment one are improved compared with the embodiment one, and finally the photoelectric conversion efficiency of the solar cell is improved. This proves that the addition of GeO2 in the glass powder can effectively reduce the corrosiveness of the electrode paste, and the low-corrosion electrode paste is more easy to form a good electrical contact with the second doped polysilicon layer, and is not easy to produce excessive ablation, thereby reducing the interface recombination, improving the open-circuit voltage and the fill factor.

[0148] Further comparing the data of Example 1 and Comparative Example 2, it can be seen that the fill factor and photoelectric conversion efficiency of Example 1 are higher than those of Comparative Example 2. This indicates that the content of GeO2 is not the higher the better, and the excessive addition is not conducive to forming a good contact, and will also cause an increase in carrier recombination, reducing the fill factor and photoelectric conversion efficiency.

[0149] Combining the data of Example 1 and Comparative Example 3, it can be seen that the open-circuit voltage, short-circuit current and fill factor of Example 1 are all significantly improved compared with those of Comparative Example 3, finally making the photoelectric conversion efficiency of the solar cell significantly improved. This proves that the laser-induced sintering plays a key role in promoting the first electrode and the second doped polysilicon layer to form a good contact, and the overall efficiency of the solar cell decreases by using the high-temperature sintering process.

[0150] By comparing Example 1 with Example 2 and Example 3, it can be seen that the performance of the solar cell of Example 1 is the best. This proves that when the mass ratio of PbO to GeO2 in the glass powder is at a specific value, the contact effect of the first electrode and the second doped polysilicon layer is better, which promotes the overall performance of the solar cell to be improved.

[0151] The above has introduced the technical solutions disclosed in the embodiments of the present application in detail, and the principles and implementation modes of the present application have been described by applying specific examples. The above description of the embodiments is only for helping to understand the technical solutions and core invention points of the embodiments of the present application. At the same time, for those skilled in the art, according to the idea of the present application, the specific implementation modes and application ranges will be changed, and the above description of the embodiments should not be understood as limiting the present application.

Claims

1. A method for producing a solar cell, characterized by, The method comprises the following steps: a medium layer and a doped layer are prepared on a surface of a silicon substrate, the doped layer has a thickness of 30nm-90nm; a first aluminum oxide layer is prepared on a side of the doped layer away from the silicon substrate; a first electrode is prepared, comprising: printing an electrode paste, the electrode paste comprising conductive metal powder, glass powder and organic carrier; a sintering process, the sintering process comprising laser-induced sintering, the first electrode passing through the first aluminum oxide layer and forming contact with the doped layer; the glass powder comprises the following components by mass percentage:

2. The method for producing a solar cell according to claim 1, wherein the mass ratio of PbO to GeO2 is (8:1)-(15:1).

3. The method for manufacturing a solar cell according to claim 1, wherein the glass powder further comprises Li2O with a mass percentage of 0.1%-3.5%.

4. The method for manufacturing a solar cell according to claim 1, wherein the first aluminum oxide layer has a thickness of 0.5nm-2.9nm.

5. The method for manufacturing a solar cell according to claim 1, wherein the mass ratio of the conductive metal powder, the glass powder and the organic carrier is (75%-90%): (0.5％～4.5％)：(5％～15％)。 6. The method for manufacturing a solar cell according to claim 1, wherein the conductive metal powder comprises one or more of silver, copper, aluminum or zinc.

7. The method for manufacturing a solar cell according to claim 1, wherein the doped layer comprises a first doped polysilicon layer, a first silicon oxide layer and a second doped polysilicon layer arranged in sequence on a surface of the medium layer; the surface doping concentration of the doping element in the second doped polysilicon layer is greater than the surface doping concentration of the doping element in the first doped polysilicon layer; the first electrode forms contact with the second doped polysilicon layer.

8. The method for manufacturing a solar cell according to claim 7, wherein the first doped polysilicon layer has a thickness of 5nm-18nm, the first silicon oxide layer has a thickness of 2nm-10nm, and the second doped polysilicon layer has a thickness of 10nm-75nm.

9. The method for manufacturing a solar cell according to claim 8, wherein The surface doping concentration of the doping element in the first doped polysilicon layer is 1 x 10 19 / cm 3 ~ 5 x 10 21 / cm 3 . the surface doping concentration of the doping element in the second doped polysilicon layer is 2× 10 20 / cm 3 ~ 9 x 10 21 / cm 3 .

10. The method of producing a solar cell according to any one of claims 1 to 9, wherein the medium layer, the doped layer, the first aluminum oxide layer and the first electrode are located on a back light side of the silicon substrate; a first passivation layer is further prepared on a side of the first aluminum oxide layer away from the silicon substrate, the first passivation layer comprising one or more combinations of a first silicon nitride layer, a first silicon oxynitride layer or a second silicon oxide layer; a first diffusion layer is provided on a light receiving side of the silicon substrate, and a second passivation layer is provided on a side of the first diffusion layer away from the silicon substrate, the second passivation layer comprising one or more combinations of a second aluminum oxide layer, a second silicon nitride layer, a second silicon oxynitride layer or a third silicon oxide layer; a second electrode is further provided on the light receiving side of the silicon substrate, the second electrode passing through the second passivation layer and forming contact with the first diffusion layer.

11. The method of producing a solar cell according to any one of claims 1 to 9, wherein the sintering process comprises low-temperature sintering and the laser-induced sintering in sequence, the sintering temperature of the low-temperature sintering being less than the peak sintering temperature of the electrode paste.

12. The method of producing a solar cell according to claim 11, wherein the sintering temperature of the low-temperature sintering is 500°C-650°C; and / or, The laser power density of the laser-induced sintering is 40 kW / cm 2 ~ 55 kW / cm 2 , the pulse width is 10 ns~200 ns, the spot diameter is 0.8 μm~1.5 μm, and the scanning speed is 4 m / s~7 m / s.

13. The method of producing a solar cell according to claim 11, wherein a light injection process is performed before the laser-induced sintering step; or, a light injection process is performed after the laser-induced sintering step.

14. A photovoltaic module, characterized by a solar cell prepared by the preparation method of any one of claims 1-13.

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