Solar cell, preparation method thereof and photovoltaic module

Abstract

The invention provides a solar cell, a preparation method thereof and a photovoltaic module, and relates to the field of photovoltaic technology. The solar cell includes: a silicon substrate; the doped semiconductor layer, the protective layer and the base metal gate line are sequentially arranged on the silicon substrate; the base metal grid line comprises a first layer far away from the silicon substrate and a second layer close to the silicon substrate; the bonding degree between particles in the first layer is greater than that between particles in the second layer; the first layer comprises a base metal simple substance; the second layer comprises a base metal simple substance, a base metal oxide and a phosphorus element; and the protection layer contains phosphorus element. In the invention, the base metal grid lines are used, so that the cost of the grid lines is obviously reduced; in addition, phosphorus in the second layer plays a bridging role, phosphorus in the second layer can exist in a phosphate radical mode, phosphate radicals can be combined with the base metal oxide to form an inorganic binder, the first layer and the protective layer are bonded, and it is further guaranteed that the base metal grid lines have good adhesive force on the protective layer.

Description

Technical Field

[0001] The present invention relates to the field of photovoltaic technology, in particular to a solar cell and a preparation method thereof, and a photovoltaic module. Background Art

[0002] Solar cells are semiconductor devices that convert light energy into electrical energy through the photovoltaic effect. Since they use clean energy, they have broad application prospects.

[0003] The grid lines in solar cells are used to collect and conduct current. Currently, the commonly used grid lines are mainly silver grid lines.

[0004] However, the high cost of silver grid lines leads to high costs of solar cells, which affects the promotion and application of solar cells. Summary of the Invention

[0005] The present invention provides a solar cell and a preparation method thereof, and a photovoltaic module, aiming to solve the problem of high cost of silver grid lines in existing solar cells.

[0006] A first aspect of the present invention provides a solar cell comprising:

[0007] Silicon substrate;

[0008] A doped semiconductor layer, a protective layer, and a base metal gate line are sequentially arranged on the silicon substrate; the base metal gate line comprises: a first layer away from the silicon substrate and a second layer close to the silicon substrate; the degree of adhesion between particles in the first layer is greater than the degree of adhesion between particles in the second layer; the first layer comprises a base metal element; the second layer comprises: a base metal element, a base metal oxide, and phosphorus; and the protective layer contains phosphorus.

[0009] In the present application, firstly, base metal grid lines are used, eliminating the need for precious metals, which significantly reduces the cost of the grid lines; secondly, the base metal elements in the second layer can achieve good current collection and conduction to the first layer, and the base metal elements in the first layer ensure good current collection and conduction performance; thirdly, the degree of adhesion between particles in the first layer is greater, which not only makes the base metal element particles more tightly bonded and has better conductivity, but also increases the bonding force with the interconnecting components; since the second layer contains non-conductive or slightly weakly conductive base metal oxides and phosphorus elements, the degree of adhesion between particles in the second layer is slightly smaller. Furthermore, some particles in the second layer may also be in an unbonded state, presenting the second layer as an intermittent or discontinuous state, avoiding the formation of a large whole by the non-conductive or slightly weakly conductive base metal oxides and phosphorus elements. The body affects the current collection effect; fourth, the protective layer contains phosphorus, that is, the phosphorus in the second layer at least partially penetrates the protective layer, and the phosphorus can also react with the base metal oxide in the second layer to form a base metal phosphide, that is, the phosphorus in the second layer not only connects the protective layer, but also connects the base metal oxide in the second layer, plays a bridging role, and ensures that the base metal grid line has good adhesion on the protective layer, avoiding the base metal grid line from being pulled off or falling off from the protective layer during long-term service; fifth, the phosphorus in the second layer can also exist in the form of phosphate, which will combine with the base metal oxide to form an inorganic binder, playing the role of bonding the first layer and the protective layer, further ensuring that the base metal grid line has good adhesion on the protective layer, avoiding the base metal grid line from being pulled off or falling off from the protective layer during long-term service. In summary, in the solar cell provided by the present application, the base metal grid line has a low cost and excellent conductive performance, and at the same time has a better bonding force with the protective layer, avoiding the base metal grid line from being pulled off or falling off from the protective layer during long-term service.

[0010] In some possible embodiments, the thickness of the first layer is greater than the thickness of the second layer.

[0011] Since the second layer contains non-conductive or weakly conductive base metal oxides and phosphorus elements, the conductivity of the second layer may be weaker than that of the first layer. Therefore, in this application, the first layer is thicker to ensure good conductivity of the base metal grid line.

[0012] In some possible embodiments, both the first layer and the second layer contain oxygen; the mass proportion of oxygen in the second layer is greater than the mass proportion of oxygen in the first layer; and / or,

[0013] The mass proportion of the base metal element in the first layer is greater than the mass proportion of the base metal element in the second layer; and / or,

[0014] The first layer further includes phosphorus, and the mass proportion of the phosphorus in the second layer is greater than the mass proportion of the phosphorus in the first layer.

[0015] The oxygen element accounts for a relatively small proportion by mass in the first layer, indicating that the reduction reaction of the base metal oxide in the first layer is more thorough, so the base metal element in the first layer has a higher mass content and better conductivity. In the second layer, the oxygen mass content is relatively high, and it can form more phosphates with phosphorus. The phosphates will combine with cuprous oxide to form an inorganic binder, further enhancing the bonding effect between the first layer and the protective layer, further ensuring that the base metal grid lines have good adhesion to the protective layer, and avoiding the base metal grid lines being pulled off or falling off from the protective layer during long-term service.

[0016] In some possible embodiments, at least the second layer contains a reducing agent, and the reducing agent includes: polyvinylpyrrolidone.

[0017] When subjected to appropriate heat, polyvinyl pyrrolidone can quickly and thoroughly reduce non-conductive or weakly conductive base metal oxides into base metal elements; in addition, polyvinyl pyrrolidone can also stably and evenly disperse base metal oxide particles when preparing base metal slurries.

[0018] In some possible embodiments, the reducing agent further includes: at least one of ascorbic acid, glucose, ethylenediamine, and formic acid.

[0019] In some possible embodiments, the first layer contains the reducing agent; the mass proportion of the reducing agent in the first layer is smaller than the mass proportion of the reducing agent in the second layer.

[0020] The reduction reaction in the first layer is more thorough, the copper content in the first layer is higher, and the conductive performance is better.

[0021] In some possible embodiments, at least the second layer contains a phosphorus-containing adhesion additive; the phosphorus-containing adhesion additive includes at least one of sodium hypophosphite, phosphoric acid, ammonium hypophosphite, ammonium dihydrogen phosphate, aluminum phosphide, hexa(phosphine)ferric chloride, tetra(phosphine)nickel and other hypophosphites, metal phosphides and phosphine precursor compounds.

[0022] The above-mentioned phosphorus-containing adhesion additive will undergo a disproportionate decomposition reaction after being excited. On the one hand, it will decompose to form phosphate, which will combine with the base metal oxide itself to form an inorganic adhesive, and the inorganic adhesive will bond the first layer and the protective layer; on the other hand, it will decompose to form PH3. The P (phosphorus element) in this molecule can penetrate the protective layer and react with the base metal oxide to form a base metal phosphide. Then, P is connected to the base metal oxide in the protective layer and the second layer at the same time, that is, the P element achieves the function of bridging the protective layer and the second layer; under the action of the inorganic adhesive and the bridging, the base metal grid line and the protective layer have good adhesion on a macro scale, which prevents the base metal grid line from being pulled off or falling off from the protective layer during long-term service.

[0023] In some possible embodiments, the first layer contains the phosphorus-containing adhesion additive; the mass proportion of the phosphorus-containing adhesion additive in the first layer is smaller than the mass proportion of the phosphorus-containing adhesion additive in the second layer.

[0024] In some possible embodiments, the base metal includes at least one of copper, nickel, and aluminum.

[0025] In some possible embodiments, the base metal includes copper, and the base metal oxide includes at least one of: copper oxide nanoparticles and cuprous oxide nanoparticles;

[0026] The base metal includes nickel, and the base metal oxide includes at least one of nickelous oxide nanoparticles, nickel trioxide nanoparticles, and nickel dioxide nanoparticles;

[0027] The base metal includes aluminum, and the base metal oxide includes aluminum oxide nanoparticles.

[0028] Cuprous oxide nanoparticles, copper oxide nanoparticles, nickelous oxide nanoparticles, nickel tetroxide nanoparticles, nickel sesquioxide nanoparticles, and aluminum oxide nanoparticles are easy to heat up and be reduced due to their small particle size, and can further improve the conductivity of the base metal grid line.

[0029] In some possible embodiments, the protective layer includes one of a dielectric layer and a conductive layer; and / or,

[0030] The base metal oxide includes base metal oxide nanoparticles.

[0031] In some possible embodiments, the dielectric layer includes at least one of silicon nitride, silicon oxynitride, and aluminum oxide;

[0032] The conductive layer includes TCO.

[0033] A second aspect of the present invention provides a method for preparing a solar cell, comprising:

[0034] providing a silicon substrate;

[0035] sequentially arranging a doped semiconductor layer and a protective layer on the silicon substrate;

[0036] A base metal slurry is disposed on a side of the protective layer away from the silicon substrate and solidified to obtain a base metal grid line; the base metal slurry comprises, by mass percentage, 30% to 90% of a base metal source, 6% to 25% of a reducing agent, 0.1% to 10% of a phosphorus-containing adhesion additive, and 4% to 55% of a solvent; the base metal source comprises a base metal oxide; and the reducing agent comprises polyvinyl pyrrolidone.

[0037] In some possible embodiments, the curing step includes:

[0038] At least one of laser sintering, photon sintering, infrared sintering, and sintering furnace thermal sintering.

[0039] In some possible embodiments, during the laser sintering process:

[0040] Lasers include continuous lasers and pulsed lasers with a wavelength of 500nm-1100nm; and / or,

[0041] Laser pulse width is greater than or equal to 100 fs; and / or,

[0042] The frequency of the pulsed laser is ≥ 100 kHz; and / or,

[0043] Laser power ≥ 10 mW; and / or,

[0044] Laser scanning speed ≥1mm / s.

[0045] A third aspect of the present invention provides a photovoltaic assembly comprising: a plurality of battery strings;

[0046] The cell string includes: a plurality of interconnecting elements and any one of the aforementioned solar cells, wherein the interconnecting elements are used to connect the plurality of solar cells in series through base metal grid lines.

[0047] The above-mentioned solar cells and preparation methods thereof and photovoltaic modules have the same or similar beneficial effects, and are not described in detail here to avoid repetition. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0049] Figure 1 A schematic diagram of a partial cross-sectional structure of a solar cell in an embodiment of the present invention is shown;

[0050] Figure 2 shows an SEM image of a base metal grid line of a solar cell according to an embodiment of the present invention;

[0051] Figure 3 shows a locally enlarged SEM image of a first layer in an embodiment of the present invention;

[0052] Figure 4 shows a locally enlarged SEM image of a second layer in an embodiment of the present invention;

[0053] Figure 5 A local EDS image of a solar cell according to an embodiment of the present invention is shown.

[0054] Description of the accompanying figures:

[0055] 1-silicon substrate, 2-doped semiconductor layer, 3-protective layer, 4-base metal gate line, 41-first layer, 42-second layer. DETAILED DESCRIPTION

[0056] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0057] The present invention provides a solar cell, referring to Figure 1 The solar cell comprises: a silicon substrate 1, a doped semiconductor layer 2, a protective layer 3, and a base metal grid line 4 sequentially disposed on the silicon substrate 1. The silicon substrate 1 may be N-type single crystal silicon or P-type single crystal silicon, capable of providing long-life carriers. The doped semiconductor layer 2 may comprise: at least one of a P-type doped semiconductor layer and an N-type doped semiconductor layer. The P-type doped semiconductor layer may contain one or more elements from Group IIIA (e.g., boron). The N-type doped semiconductor layer may contain one or more elements from Group VA (e.g., phosphorus). In terms of the arrangement of the materials, the crystalline phase of the doped semiconductor layer 2 may be amorphous, microcrystalline, nanocrystalline, single crystal, or polycrystalline. The doped semiconductor layer 2 may be prepared by in-situ doping or ex-situ doping, without limitation. The protective layer 3 may protect the doped semiconductor layer 2 and the silicon substrate 1 thereunder. The base metal grid line 4 is used to collect and conduct carriers or current.

[0058] More specifically, along the thickness direction L1 of the silicon substrate 1, the silicon substrate includes two opposite sides, namely, its light-facing side and its backlight side. During the operation of the solar cell, the side of the silicon substrate 1 that mainly receives light is its light-facing side, and the backlight side is opposite to the light-facing side. The above-mentioned doped semiconductor layer 2, protective layer 3 and base metal grid line 4 can be sequentially arranged on at least one side of the light-facing side and the backlight side of the silicon substrate 1, and this application does not make specific restrictions on this. The solar cell can be a double-sided solar cell with grid lines on both sides, such as a TOPcon (tunneling passivated contact cell), or a back-contact solar cell with grid lines only on the backlight side, and there is no restriction on this.

[0059] SEM images refer to scanning electron microscope images, and EDS images refer to energy dispersive X-ray spectroscopy measurement images. EDS can be used to characterize element distribution. Figure 2 This is the SEM image of the cross section of the base metal gate line 4. Figure 2 The red dotted line on one side is the first layer 41, and the other side is the second layer 42. Figure 5 In FIG, the first layer 41 and the second layer 42 are located on both sides of the red dotted line. Figure 3 for Figure 2 The enlarged SEM image of the first layer of the part circled by the red oval dotted circle, Figure 4 for Figure 2 The enlarged SEM image of the second layer of the part circled by the red square dotted circle. Figure 2 and Figure 5 The base metal gate line 4 includes a first layer 41 away from the silicon substrate 1 and a second layer 42 close to the silicon substrate 1. Figures 2 to 4The degree of adhesion between particles in the first layer 41 is greater than the degree of adhesion between particles in the second layer 42, and at least part of the particles in the first layer 41 extend into the second layer 42, further improving the conductive performance. The particles here can refer to: particles, atoms, ions, etc. The degree of adhesion between particles in this application can include: the degree of overlap between particles, the degree of contact between particles, the degree of interweaving between particles, the degree of mutual diffusion between particles, the degree of fusion between particles, etc. Whether there are chemical bonds between particles is not specifically limited here, for example, chemical bonds may exist or not. That is, the degree of overlap, contact, interweaving, mutual diffusion, and fusion between particles in the first layer is correspondingly greater than the degree of overlap, interweaving, mutual diffusion, and fusion between particles in the second layer, or in other words, the particles in the first layer are distributed more densely, and the particles in the second layer are distributed more discretely or separately. Furthermore, some particles in the second layer may also be in an unbonded state, presenting a discontinuous or discontinuous state in the second layer. Here, the degree of interparticle adhesion in the first layer and the degree of interparticle adhesion in the second layer can be compared by selecting the first and second layers in regions of the same size, such as 1 μm×1 μm, at the same magnification. One method can be to compare the total number of overlapping, contacting, interwoven, diffused, or intermingled particle pairs in the first layer and the second layer, with the total number of such particle pairs in the first layer of the same size being greater than the total number of such particle pairs in the second layer of the same size. Another method can be to compare the total number of separated particle pairs in the first layer and the second layer, with the total number of separated particle pairs in the first layer of the same size being less than the total number of separated particle pairs in the second layer of the same size. Yet another method can be to compare the average spacing between particles in the first layer and the second layer, with the average spacing in the first layer of the same size being less than the average spacing in the second layer of the same size. Methods for comparing the degree of interparticle adhesion in the first layer and the degree of interparticle adhesion in the second layer include, but are not limited to, the aforementioned examples.

[0060] It should be noted that, at the same magnification scale, for example, at a scale of 1 micron, the state of the second layer is similar to a sheet, and the state of the first layer is similar to mutually bonded spheres.

[0061] In some embodiments, some particles in the second layer may be unbonded, resulting in the second layer being discontinuous or discontinuous, thereby preventing the non-conductive or weakly conductive base metal oxides and phosphorus elements from forming a larger overall structure that affects the current collection effect.

[0062] Reference Figure 5 , the first layer 41 includes a base metal element (e.g., Figure 5 The medium yellow represents copper); the second layer 42 includes: a base metal element (for example, Figure 5 Medium yellow represents copper), base metal oxides (e.g. Figure 5 The red dots represent oxygen) and phosphorus (e.g. Figure 5 The lake blue in the middle represents phosphorus); the protective layer 3 contains phosphorus. First, the base metal grid line 4 is used, and there is no need to use precious metals, which significantly reduces the cost of the grid line; second, the base metal element in the second layer 42 can achieve good current collection and conduction to the first layer 41, and the base metal element in the first layer 41 ensures good current collection and conduction performance; third, the degree of adhesion between the particles in the first layer 41 is greater, which not only makes the base metal element particles more closely bonded and has better conductivity, but also increases the bonding force with the interconnection parts; because the second layer 42 contains non-conductive or slightly weakly conductive base metal oxides and phosphorus elements, the degree of adhesion between the particles in the second layer 42 is slightly smaller, avoiding the non-conductive or slightly weakly conductive base metal oxides and phosphorus elements from forming a larger overall effect on the current collection effect, and also allows part of the first layer 41 to extend into the second layer 42 to further increase the conductivity of the base metal grid line 4. Fourth, the protective layer 3 contains phosphorus, that is, the phosphorus in the second layer 42 at least partially penetrates into the protective layer 3, and the phosphorus can also react with the base metal oxide in the second layer 42 to form a base metal phosphide, that is, the phosphorus in the second layer 42 not only connects to the protective layer 3, but also connects to the base metal oxide in the second layer 42, plays a bridging role, and ensures that the base metal grid line 4 has good adhesion on the protective layer 3, and avoids the base metal grid line 4 from being pulled off or falling off from the protective layer 3 during long-term service; Fifth, the phosphorus in the second layer 42 can also exist in the form of phosphate, which will combine with the base metal oxide to form an inorganic binder, and play the role of bonding the first layer 41 and the protective layer 3, further ensuring that the base metal grid line 4 has good adhesion on the protective layer 3, and avoids the base metal grid line 4 from being pulled off or falling off from the protective layer 3 during long-term service. In summary, in the solar cell provided in this application, the base metal grid line 4 has low cost and excellent conductivity, and at the same time has better bonding strength with the protective layer 3, thus preventing the base metal grid line 4 from being pulled off or falling off from the protective layer 3 during long-term service.

[0063] For example, the base metal here includes copper, then the phosphorus in the second layer 42 at least partially penetrates into the protective layer 3, and the phosphorus can also react with the copper oxide and cuprous oxide in the second layer 42 to form copper phosphide, that is, the phosphorus in the second layer 42 not only connects to the protective layer 3, but also connects to the copper oxide and cuprous oxide in the second layer 42, playing a bridging role, ensuring that the base metal grid line 4 has good adhesion on the protective layer 3, and avoiding the base metal grid line 4 from being pulled off or falling off from the protective layer 3 during long-term service; the phosphorus in the second layer 42 can also exist in the form of phosphate, which will combine with copper oxide and cuprous oxide to form an inorganic binder, playing the role of bonding the first layer 41 and the protective layer 3, further ensuring that the base metal grid line 4 has good adhesion on the protective layer 3, and avoiding the base metal grid line 4 from being pulled off or falling off from the protective layer 3 during long-term service.

[0064] In some possible embodiments, reference Figure 2 and Figure 5 , the thickness of the first layer 41 is greater than that of the second layer 42. Specifically, because the second layer 42 contains base metal oxides and phosphorus elements with slightly weaker conductivity, the conductivity of the second layer 42 may be weaker than that of the first layer 41. The thinner second layer 42 can improve the adhesion between the base metal grid lines 4 and the protective layer while avoiding possible negative impacts on the overall conductivity. Therefore, in this application, the first layer 41 is thicker to ensure good conductivity of the base metal grid lines 4. The specific thickness difference between the first layer 41 and the second layer 42 is not limited here.

[0065] It should be noted that the thickness of the first layer 41 and the thickness of the second layer 42 are both parallel to the thickness direction L1 of the silicon substrate 1. If the thickness of the first layer 41 varies at different locations, the thickness of the first layer 41 can be the average distance between the farthest boundaries at multiple locations along the thickness direction of the silicon substrate, where "multiple" here means two or more. The thickness of the second layer 42 is determined in a similar manner and will not be further described to avoid repetition.

[0066] In some possible embodiments, reference Figure 5, both the first layer 41 and the second layer 42 contain oxygen elements; the mass proportion of oxygen elements in the second layer 42 is greater than the mass proportion of oxygen elements in the first layer 41. Specifically, in the present application, the base metal element in the base metal grid line 4 is obtained by reducing the base metal oxide. The mass proportion of oxygen elements in the first layer 41 is relatively small, indicating that the reduction reaction of the base metal oxide in the first layer is relatively thorough, and the mass content of the base metal element in the first layer 41 is relatively high, and the conductive performance is better; in the second layer 42, the mass content of oxygen is relatively high, and it can form more phosphate groups with phosphorus. The phosphate groups will combine with cuprous oxide to form an inorganic binder, further enhancing the bonding effect on the first layer 41 and the protective layer 3, further ensuring that the base metal grid line 4 has good adhesion to the protective layer 3, and avoiding the base metal grid line 4 from being pulled off or falling off from the protective layer 3 during long-term service. The difference in the mass content of oxygen in the first layer 41 and the second layer 42 is not limited here.

[0067] In some possible embodiments, at least the second layer 42 contains a reducing agent, which includes polyvinyl pyrrolidone. Polyvinyl pyrrolidone, when subjected to appropriate energy, can reduce non-conductive or weakly conductive base metal oxides into elemental base metals. Furthermore, polyvinyl pyrrolidone can also ensure stable and uniform dispersion of base metal oxide particles when preparing a base metal slurry.

[0068] It should be noted that whether the first layer 41 contains a reducing agent is not limited. For example, the first layer 41 may contain a reducing agent or may not contain a reducing agent.

[0069] In some possible embodiments, when the first layer 41 contains a reducing agent, the mass content of the reducing agent in the first layer 41 may be less than the mass content of the reducing agent in the second layer 42, indicating that the reduction reaction in the first layer 41 is more thorough, the mass content of the copper element in the first layer 41 is higher, and the conductive performance is better.

[0070] In some possible embodiments, reference Figure 5 The mass proportion of the base metal element in the first layer 41 is greater than the mass proportion of the base metal element in the second layer 42. The first layer 41 has better conductivity and can promote current collection and conduction in the subsequent formation of a battery string.

[0071] In some possible embodiments, the first layer 41 further includes phosphorus. The phosphorus in the first layer 41 can also function as the aforementioned bridge and inorganic adhesive, thereby enhancing the bonding strength between the particles within the first layer 41 and between the first layer 41 and the second layer 42. If the first layer 41 also contains phosphorus, and the mass percentage of the phosphorus in the second layer 42 is greater than the mass percentage of the phosphorus in the first layer 41, the second layer 42 has a stronger bonding effect, and a greater bonding effect on the first layer 41 and the protective layer 3. Furthermore, the mass percentage of the phosphorus in the first layer 41 is smaller, and the first layer 41 has better electrical conductivity. Furthermore, because the second layer 42 is thinner, even if it contains the aforementioned non-conductive or weakly conductive phosphorus, it has little effect on the electrical conductivity of the base metal grid lines 4, allowing the base metal grid lines 4 to maintain good electrical conductivity.

[0072] In some possible embodiments, the reducing agent may further include: at least one of ascorbic acid, glucose, ethylenediamine, and formic acid. The above reducing agent can further accelerate the reduction reaction and further improve the conductive performance.

[0073] In some possible embodiments, at least the second layer 42 contains a phosphorus-containing adhesion additive; the phosphorus-containing adhesion additive includes at least one of sodium hypophosphite, phosphoric acid, ammonium hypophosphite, ammonium dihydrogen phosphate, aluminum phosphide, hexa(phosphine)ferric chloride, tetra(phosphine)nickel and other hypophosphites, metal phosphides and phosphine precursor compounds. The above-mentioned phosphorus-containing adhesion additive will undergo a disproportionate decomposition reaction after being excited. On the one hand, it will decompose to form phosphate, which will combine with the base metal oxide itself to form an inorganic adhesive, and the inorganic adhesive will bond the first layer 41 and the protective layer 3; on the other hand, it will decompose to form PH3. The P in this molecule can penetrate the protective layer 3 and react with the base metal oxide to form a base metal phosphide. Then, P is connected to the base metal oxide in the protective layer 3 and the second layer at the same time, that is, the P element achieves the function of bridging the protective layer 3 and the second layer 42; under the action of the inorganic adhesive and the bridging, the base metal grid line 4 and the protective layer 3 have good adhesion on a macro scale, which prevents the base metal grid line 4 from being pulled off or falling off from the protective layer 3 during long-term service.

[0074] For example, sodium hypophosphite undergoes a disproportionate decomposition reaction when stimulated. On the one hand, the phosphate radicals generated by the decomposition combine with copper oxide and cuprous oxide to form an inorganic adhesive, which bonds the first layer 41 and the protective layer 3. On the other hand, the disproportionate decomposition decomposes to generate PH3. The P in this molecule can penetrate the protective layer 3 and simultaneously undergo a phosphating reaction with copper oxide and cuprous oxide to generate CuP. Then, P is simultaneously connected to the copper oxide and cuprous oxide in the protective layer 3 and the second layer, that is, the P element achieves the function of bridging the protective layer 3 and the second layer 42. Under the action of the inorganic adhesive and the bridging, the base metal grid line 4 and the protective layer 3 exhibit good adhesion on a macroscopic level, thereby preventing the base metal grid line 4 from being pulled off or falling off from the protective layer 3 during long-term service.

[0075] It should be noted that whether the first layer 41 contains a phosphorus-containing adhesion additive is not limited. For example, the first layer 41 may contain a phosphorus-containing adhesion additive or may not contain a phosphorus-containing adhesion additive.

[0076] In some possible embodiments, if the first layer 41 also contains a phosphorus-containing adhesion additive, the phosphorus-containing adhesion additive can also serve as the aforementioned bridge and inorganic adhesive, thereby enhancing the bonding strength between the particles within the first layer 41 and between the first layer 41 and the second layer 42. If the first layer 41 also contains a phosphorus-containing adhesion additive, and the mass percentage of the phosphorus-containing adhesion additive in the first layer 41 is less than the mass percentage of the phosphorus-containing adhesion additive in the second layer 42, the second layer 42 has a stronger bonding effect, and a greater bonding effect between the first layer 41 and the protective layer 3. Furthermore, the smaller mass percentage of the phosphorus-containing adhesion additive in the first layer 41 leads to better electrical conductivity of the first layer 41. Furthermore, because the second layer 42 is thinner, even if it contains the aforementioned non-conductive or weakly conductive phosphorus-containing adhesion additive, it will have little effect on the electrical conductivity of the base metal grid lines 4, allowing the base metal grid lines 4 to maintain good electrical conductivity.

[0077] In some possible embodiments, the base metal includes at least one of copper, nickel, and aluminum. The base metal has good electrical conductivity and can be easily reduced to a single base metal.

[0078] In some possible embodiments, the base metal includes copper, and the base metal oxide includes copper oxide nanoparticles. On the one hand, phosphate groups combined with copper oxide themselves constitute an inorganic binder. On the other hand, disproportionate decomposition will decompose to form PH3. The P in this molecule can penetrate the protective layer 3 and simultaneously undergo a phosphating reaction with copper oxide to form CuP. The P then connects to the copper oxide in the protective layer 3 and the second layer, that is, the P element achieves the function of bridging the protective layer 3 and the second layer 42. Under the action of the inorganic binder and the bridging effect, the base metal grid line 4 and the protective layer 3 exhibit good adhesion on a macroscopic level, preventing the base metal grid line 4 from being pulled off or falling off the protective layer 3 during long-term service. Furthermore, due to the small size of the copper oxide nanoparticles, they are easily heated and easily reduced, which can further improve the conductivity of the base metal grid line 4.

[0079] In some possible embodiments, the base metal includes copper, and the base metal oxide may further include: cuprous oxide nanoparticles, which have a similar effect to copper oxide nanoparticles. Compared with copper oxide, the copper in copper oxide is divalent, while the copper in cuprous oxide is monovalent. Cuprous oxide is easier to reduce, further improving the conductivity of the gate line.

[0080] In some possible embodiments, the base metal includes nickel, and the base metal oxide may further include at least one of nickelous oxide nanoparticles, nickel trioxide nanoparticles, and nickel dioxide nanoparticles. These nanoparticles have the same or similar beneficial effects as the aforementioned copper oxide nanoparticles and cuprous oxide nanoparticles, and are not described in detail here to avoid repetition. In some possible embodiments, the base metal includes aluminum, and the base metal oxide may further include aluminum oxide nanoparticles. These nanoparticles have the same or similar beneficial effects as the aforementioned copper oxide nanoparticles and cuprous oxide nanoparticles, and are not described in detail here to avoid repetition.

[0081] In some possible embodiments, the base metal oxide includes base metal oxide nanoparticles. Nanoparticles are easily reduced upon heating due to their small size, and can further enhance the conductivity of the base metal grid lines 4 .

[0082] In some possible embodiments, the protective layer 3 includes a dielectric layer and a conductive layer. The dielectric layer can provide passivation and anti-reflection effects, and the conductive layer has functions such as optimizing current collection.

[0083] In some possible embodiments, the material of the dielectric layer may be an insulating material, including at least one of silicon nitride, silicon oxynitride, and aluminum oxide. The dielectric layer may be a single-layer structure or a multi-layer structure. In some examples, the dielectric layer may include a passivation layer, or may include other possible layers such as an anti-reflection layer, or may include a stacked passivation layer and an anti-reflection layer. The present embodiment of the application does not specifically limit the structure of the dielectric layer, and it can be arranged according to the needs of the solar cell. For example, for a TBC cell, the dielectric layer on the backlight side may include a stacked passivation layer and an anti-reflection layer; for a Topcon cell, the dielectric layer on the backlight side may include an anti-reflection layer, or may include a stacked passivation layer and an anti-reflection layer; the dielectric layer on the light-facing side of both the TBC cell and the Topcon cell may include a stacked passivation layer and an anti-reflection layer. In some examples, the material of the dielectric layer is silicon nitride. In this case, silicon nitride has a high resistivity and has good passivation and anti-reflection effects.

[0084] In some possible embodiments, the conductive layer includes a TCO (transparent conductive layer), which facilitates the collection of photogenerated carriers and enables lateral current transmission, while also reducing series resistance. Furthermore, the TCO can also block the diffusion of base metal ions into the silicon substrate.

[0085] The present application also provides a method for preparing a solar cell, comprising the following steps.

[0086] Step S1, providing a silicon substrate.

[0087] Step S2: sequentially disposing a doped semiconductor layer and a protective layer on the silicon substrate.

[0088] Step S3, placing a base metal slurry on the side of the protective layer away from the silicon substrate and curing it to obtain a base metal gate line; in terms of mass percentage, the base metal slurry includes: 30% to 90% of a base metal source, 6% to 25% of a reducing agent, 0.1% to 10% of a phosphorus-containing adhesion additive, and 4% to 55% of a solvent; the base metal source includes: a base metal oxide; and the reducing agent includes: polyvinyl pyrrolidone.

[0089] Methods for applying the base metal slurry may include spin coating, screen printing, electroplating, and other methods, with no specific limitation. The base metal source includes base metal oxides. In some possible embodiments, the base metal source may also include at least one of base metal elemental nanoparticles, inorganic base metal salts, and organic base metal salts. Base metal elemental nanoparticles can further enhance the conductivity of the base metal grid lines.

[0090] It should be noted that, in some possible embodiments, the base metal source in the base metal slurry may be one or more types, without specific limitation. For example, the base metal source in the base metal slurry may be pure copper oxide nanoparticles, or the base metal source in the base metal slurry may be copper oxide nanoparticles and copper nanoparticles, or the base metal source in the base metal slurry may be copper oxide nanoparticles, cuprous oxide nanoparticles, and copper nanoparticles.

[0091] Curing has at least two functions: first, providing heat for the reduction reaction of the base metal oxide, and second, providing heat for the decomposition reaction of the phosphorus-containing adhesion additive. That is, during the curing process, the reducing agent can reduce the base metal oxide to a single base metal to provide conductivity; the phosphorus-containing adhesion additive is used to provide phosphorus. Specifically, during the curing process, the phosphorus-containing adhesion additive undergoes a decomposition reaction to produce PH3 and phosphate. As mentioned above, PH3 and phosphate can provide good bonding with the protective layer. More specifically, the reducing agent, phosphorus-containing adhesion additive, etc. herein can be referred to the relevant descriptions above, and to avoid repetition, they are not further described.

[0092] The solvent is used to disperse the base metal source, dissolve the reducing agent and phosphorus-containing adhesion additive, and adjust the viscosity and solids content of the base metal slurry. In the base metal slurry, the solvent is primarily composed of the base metal source, reducing agent, and phosphorus-containing adhesion additive. The specific composition of the solvent is not limited; for example, the solvent may include at least one of ethylene glycol, ethanol, and deionized water.

[0093] More specifically, the base metal source is the main source of the conductive base metal element that the base metal slurry finally forms, and the reducing agent is a substance that reduces the non-conductive or weakly conductive base metal oxide to a base metal element under the action of solidification. In addition, polyvinyl pyrrolidone can also make the base metal oxide particles stably and evenly dispersed when configuring the base metal slurry. The present application can improve the adhesion of the base metal slurry on the solar cell mainly due to the interaction between solidification and the phosphorus-containing adhesion additive. The base metal source in the base metal slurry heats up rapidly after absorbing energy, and then the heat begins to diffuse to the surrounding area to form a micron-level high-temperature zone, which stimulates the phosphorus-containing adhesion additive to undergo a disproportionate decomposition reaction. On the one hand, the phosphate generated by the decomposition combines with the base metal oxide itself to form an inorganic adhesive; on the other hand, the above decomposition also generates PH3. The P in the molecule can penetrate the protective layer 3 and react with the base metal oxide to generate a base metal phosphide, which shows good adhesion on a macro scale under the bridging of P.

[0094] For example, the base metal slurry may include, by mass percentage, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90% of a base metal source, 6%, 8%, 10%, 12%, 15%, 17%, 20%, 22%, 24%, 25% of a reducing agent, 0.1%, 0.5%, 0.8%, 0.9%, 1%, 2%, 3%, 4%, 5%, 6%, 8%, 9%, 10% of a phosphorus-containing adhesion additive, and 4%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 25%, 29%, 30%, 32%, 35%, 38%, 40%, 42%, 45%, 48%, 50%, 55% of a solvent.

[0095] There is no limitation on the method of obtaining the base metal slurry. For example, 1. Weigh 1.54g (grams) of sodium hypophosphite into a three-necked flask, add 20ml of ethylene glycol, and stir at 150r / min (revolutions / minute) for 10min until dissolved to obtain a transparent colorless solution. 2. Weigh 8.02g of polyvinylpyrrolidone and slowly add it to the three-necked flask under mechanical stirring at 200r / min. After the addition is completed, add the remaining 9ml of ethylene glycol, increase the speed to 250r / min and stir for 15min, then reduce it to 50r / min and continue stirring for 3h (hours) and 15min to obtain a transparent slightly yellow solution. 3. After turning on the water bath and heating (set temperature 60℃) for 15min, weigh 37g of 100nm copper oxide particles and slowly add them to the flask at 250r / min in 15 batches. After 25min, the addition is completed, and the mechanical stirring speed is adjusted to 700r / min and stirred for 30min, and then 400r / min and stirred for 30min. 4. Finally, turn off the heating, degas and remove bubbles at 50r / min for 0.5h, and let it stand overnight to obtain black viscous base metal slurry.

[0096] In some possible embodiments, the curing step includes at least one of laser sintering, photon sintering, infrared sintering, and sintering in a sintering furnace, and the curing step can be selected in a variety of ways. It should be noted that laser sintering has a very short process time, which can prevent the reduced base metal element from being re-oxidized during the heating process. In addition, the laser sintering process time is short, so the production efficiency is high. For photon sintering, infrared sintering, and sintering in a sintering furnace, the sintering time may be longer. Sintering can be carried out under a protective atmosphere such as an inert gas to prevent the reduced base metal element from being re-oxidized during the heating process.

[0097] In some possible embodiments, the laser sintering process includes continuous laser light and pulsed laser light with a wavelength of 500 nm to 1100 nm. Specifically, base metal oxides typically have the strongest absorption in the 500 nm to 1100 nm wavelength range. Therefore, continuous laser light and pulsed laser light within the 500 nm to 1100 nm wavelength range are selected, as they are easily absorbed by base metal oxides.

[0098] For example, copper oxide, with a band gap of approximately 1.2-1.5 eV (electron volts), typically strongly absorbs yellow-green light (around 570 nm). Therefore, lasers in the 600-900 nm wavelength range can be used. Another example is laser sintering, where wavelengths include continuous and pulsed lasers at 500 nm, 515 nm, 520 nm, 532 nm, 577 nm, 589 nm, and 594 nm (yellow light); and 635 nm, 638 nm, 650 nm, 780 nm, 808 nm, 830 nm, 850 nm, 905 nm, 940 nm, 980 nm, 1064 nm, and 1100 nm.

[0099] In some possible embodiments, during the laser sintering process: the laser pulse width is greater than or equal to 100 fs (femtoseconds); and / or the pulse laser frequency is greater than or equal to 100 kHz (kilohertz); and / or the laser power is greater than or equal to 10 mW (milliwatts); and / or the laser scanning speed is greater than or equal to 1 mm / s (millimeter / second). Too little laser energy will fail to activate and decompose the phosphorus-containing adhesion additive in the base metal slurry, thereby failing to achieve the effect of increasing adhesion, nor will it provide energy for the base metal oxide reduction reaction. Excessive laser energy may damage structures such as the silicon substrate. Therefore, adjusting the laser process parameters within the above-mentioned corresponding ranges can not only fully ensure the smooth activation of the phosphorus-containing adhesion additive in the base metal slurry and the base metal oxide reduction reaction, but also prevent damage to structures such as the silicon substrate.

[0100] For example, in laser sintering, the laser pulse width can be 100fs, 120fs, 150fs, 180fs, 200fs, 240fs, 250fs, 280fs, 300fs, 330fs, 350fs, 400fs; the pulse laser frequency can be 100KHz, 120KHz, 150KHz, 180KHz, 200KHz, 230KHz, 250KHz, 290KHz, 300KHz, 310KHz, 330KHz, 350KHz, 400KHz, 4 20KHz, 450KHz; the laser power can be 10mW, 11mW, 15mW, 19mW, 20mW, 23mW, 25mW, 39mW, 30mW, 33mW, 35mW, 40mW, 44mW, 45mW, 50mW; the laser scanning speed can be 1mm / s, 2mm / s, 5mm / s, 8mm / s, 10mm / s, 11mm / s, 15mm / s, 18mm / s, 20mm / s, 21mm / s, 25mm / s, 28mm / s, 30mm / s.

[0101] It should be noted that when the protective layer is a dielectric layer, a seed layer is further provided under the base metal grid line 4 in the present application, and the seed layer can be nickel, silver, etc. For example, between the aforementioned steps S2 and S3, the method may further include: providing a through hole in a local position of the protective layer so that the doped semiconductor is partially exposed, providing a nickel seed layer on the exposed doped semiconductor, the nickel seed layer being in contact with the doped semiconductor, and then providing a base metal slurry. The seed layer here can play a certain role in blocking the base metal elements in the base metal grid line from diffusing inward. When a through hole is provided in the protective layer, the width of the through hole is smaller than the width of the base metal grid line; or, between the aforementioned steps S2 and S3, the method may further include: locally providing a silver paste on the protective layer, and then sintering at a high temperature. The silver paste contains glass powder, and the silver paste is a penetrating silver paste. During the high-temperature sintering process, the silver paste penetrates the protective layer and contacts the doped semiconductor, and then providing a base metal slurry on the silver seed layer. In the case where the protective layer is TCO, the base metal slurry may be directly disposed on the TCO. The TCO may also play a role in preventing the base metal elements in the base metal grid lines from diffusing inwards.

[0102] The present application also provides a photovoltaic module comprising a plurality of cell strings; the cell strings comprise: a plurality of interconnects and a plurality of any of the aforementioned solar cells, wherein the interconnects are used to connect the plurality of solar cells in series via base metal grid lines. The interconnects may be directly electrically connected to the base metal grid lines, or indirectly electrically connected to the base metal grid lines via other structures, without specific limitation. The interconnects herein may include solder ribbons, conductive backsheets, and the like.

[0103] There is no limitation on whether the photovoltaic module includes other structures. For example, the photovoltaic module may also include an encapsulation film and a cover plate located on the battery string.

[0104] The present application is further explained below with reference to specific examples.

[0105] Example 1

[0106] A silicon substrate 1 is provided; a doped semiconductor layer 2 and a protective layer 3 are sequentially arranged on the silicon substrate 1, wherein the protective layer is a silicon nitride layer; a seed layer, which may be a silver seed layer, is disposed on the side of the protective layer 3 facing away from the silicon substrate 1. After high-temperature sintering, the silver seed layer burns through the silicon nitride layer and contacts the doped semiconductor layer 2. A base metal slurry is then printed on the seed layer and laser sintered to form base metal grid lines 4. The base metal slurry comprises, by weight, 60% copper source, 17.5% reducing agent, 3% phosphorus-containing adhesion additive, and solvent; the copper source comprises cuprous oxide nanoparticles, cupric oxide nanoparticles, and copper nanoparticles; the reducing agent comprises polyvinyl pyrrolidone; and the solvent is ethylene glycol. The laser sintering process utilizes a picosecond green laser with a wavelength of 532 nm and a pulse width of 9 ps. The laser power is set to 0.15 W, the frequency to 100 kHz, and the laser scanning speed to 10 mm / s.

[0107] SEM observations revealed that the base metal grid line 4 includes a first layer 41 and a second layer 42. The degree of inter-particle bonding in the first layer 41 is greater than that in the second layer 42. EDS analysis of the elements in the base metal grid line 4 revealed that the first layer 41 includes copper; the second layer 42 includes copper, cuprous oxide, cupric oxide, and phosphorus; and the protective layer 3 contains phosphorus.

[0108] 3M tape failed to peel the base metal grid lines 4 from the protective layer 3, indicating a strong bond between the base metal grid lines 4 and the protective layer. Next, solder pads were placed on the surface of the base metal grid lines 4, and the solder ribbon was soldered to the pads. Lead wires were attached to the solder ribbons, and these remained attached even when pulled by a 300g weight, demonstrating a strong bond between the electrode structure, solder ribbon, and the battery body.

[0109] The following only describes the differences between the examples or comparative examples and Example 1, and the similarities are not repeated.

[0110] Example 2

[0111] In Example 2, the protective layer is TCO, and the remaining contents, test methods, and test results are consistent with Example 1.

[0112] Example 3

[0113] In Example 3, photon curing is used in an inert atmosphere, and the remaining contents, test methods and test results are consistent with those of Example 1.

[0114] Comparative Example 1

[0115] In Comparative Example 1, the slurry includes: 60% of a copper source and a low-temperature resin, and the copper source is copper particles. The base metal grid lines of Comparative Example 1 were observed by SEM to show no stratification, and the main component of the base metal grid lines was copper. The other parts of the battery of Comparative Example 1 are the same as those of Example 1. Under the same test environment, the base metal grid lines can be peeled off from the surface of the protective layer 3 using 3M tape, indicating that the bonding force between the base metal grid lines and the protective layer is poor. Then, a soldering pad is set on the surface of the base metal grid line using the same process parameters, and then the soldering ribbon is soldered to the soldering pad. A lead-out wire is set for the soldering ribbon, and the lead-out wire detaches from the battery when pulling a 50g weight, indicating that the bonding force between the entire electrode structure, the soldering ribbon and the battery body is relatively small.

[0116] By comparing Examples 1 to 3 with Comparative Example 1, it can be concluded that in the present application, during the curing process, the phosphorus-containing adhesion additive undergoes a decomposition reaction to decompose PH3 and phosphate, and the phosphate combines with copper oxide and cuprous oxide to form an inorganic adhesive. The P in PH3 can penetrate the protective layer 3 and simultaneously undergo a phosphating reaction with cuprous oxide and cupric oxide to generate CuP. Then, the P is simultaneously connected to the cuprous oxide and cupric oxide in the protective layer 3 and the second layer, that is, the P element achieves the function of bridging the protective layer 3 and the second layer 42. Under the action of the inorganic adhesive and the bridging, the base metal gate line 4 and the protective layer 3 exhibit good adhesion on a macro scale.

[0117] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0118] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are protected by the present invention.

Claims

1. A solar cell, characterized in that: include: Silicon substrate; A doped semiconductor layer, a protective layer, and a base metal gate line are sequentially arranged on the silicon substrate; the base metal gate line comprises: a first layer away from the silicon substrate and a second layer close to the silicon substrate; the degree of adhesion between particles in the first layer is greater than the degree of adhesion between particles in the second layer; the first layer comprises a base metal element; the second layer comprises: a base metal element, a base metal oxide, and phosphorus; and the protective layer contains phosphorus.

2. The solar cell according to claim 1, wherein The thickness of the first layer is greater than the thickness of the second layer.

3. The solar cell according to claim 1, wherein The first layer and the second layer both contain oxygen; the mass proportion of oxygen in the second layer is greater than the mass proportion of oxygen in the first layer; and / or, The mass proportion of the base metal element in the first layer is greater than the mass proportion of the base metal element in the second layer; and / or, The first layer further includes phosphorus, and the mass proportion of the phosphorus in the second layer is greater than the mass proportion of the phosphorus in the first layer.

4. The solar cell according to claim 1, wherein At least the second layer contains a reducing agent, and the reducing agent includes polyvinyl pyrrolidone.

5. The solar cell according to claim 4, wherein The reducing agent further comprises: at least one of ascorbic acid, glucose, ethylenediamine, and formic acid.

6. The solar cell according to claim 4, characterized in that The first layer contains the reducing agent; the mass proportion of the reducing agent in the first layer is smaller than the mass proportion of the reducing agent in the second layer.

7. The solar cell according to claim 1, wherein At least the second layer contains a phosphorus-containing adhesion additive; the phosphorus-containing adhesion additive includes at least one of sodium hypophosphite, phosphoric acid, ammonium hypophosphite, ammonium dihydrogen phosphate, aluminum phosphide, hexa(phosphine)ferric chloride, tetra(phosphine)nickel and other hypophosphites, metal phosphides and phosphine precursor compounds.

8. The solar cell according to claim 7, characterized in that The first layer contains the phosphorus-containing adhesion additive; the mass proportion of the phosphorus-containing adhesion additive in the first layer is smaller than the mass proportion of the phosphorus-containing adhesion additive in the second layer.

9. The solar cell according to claim 1, wherein The base metal includes at least one of copper, nickel, and aluminum.

10. The solar cell according to claim 9, characterized in that The base metal includes copper, and the base metal oxide includes at least one of cuprous oxide nanoparticles and cupric oxide nanoparticles; The base metal includes nickel, and the base metal oxide includes at least one of nickelous oxide nanoparticles, nickel trioxide nanoparticles, and nickel dioxide nanoparticles; The base metal includes aluminum, and the base metal oxide includes aluminum oxide nanoparticles.

11. The solar cell according to claim 1, wherein The protective layer includes one of a dielectric layer and a conductive layer; and / or, The base metal oxide includes base metal oxide nanoparticles.

12. The solar cell according to claim 11, characterized in that The dielectric layer includes at least one of silicon nitride, silicon oxynitride, and aluminum oxide; The conductive layer includes TCO.

13. A method for preparing a solar cell, characterized in that: include: providing a silicon substrate; sequentially arranging a doped semiconductor layer and a protective layer on the silicon substrate; Disposing a base metal slurry on a side of the protective layer away from the silicon substrate and curing the slurry to obtain a base metal gate line; The base metal slurry comprises, by mass percentage, 30% to 90% of a base metal source, 6% to 25% of a reducing agent, 0.1% to 10% of a phosphorus-containing adhesion additive, and 4% to 55% of a solvent; the base metal source comprises base metal oxide; and the reducing agent comprises polyvinyl pyrrolidone.

14. The method for preparing a solar cell according to claim 13, wherein: The curing steps include: At least one of laser sintering, photon sintering, infrared sintering, and sintering furnace thermal sintering.

15. The method for preparing a solar cell according to claim 14, wherein: In the laser sintering process: Lasers include continuous lasers and pulsed lasers with a wavelength of 500nm-1100nm; and / or, Laser pulse width is greater than or equal to 100 fs; and / or, The frequency of the pulsed laser is ≥ 100 kHz; and / or, Laser power ≥ 10 mW; and / or, Laser scanning speed ≥1mm / s.

16. A photovoltaic module, characterized in that: include: Multiple battery strings; The cell string comprises: a plurality of interconnectors and a plurality of solar cells according to any one of claims 1 to 12, wherein the interconnectors are used to connect a plurality of the solar cells in series through base metal grid lines.

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