Front side leco silver paste and method of making same, electrode

Abstract

The application discloses a front LECO silver paste, a preparation method thereof and an electrode. According to the front LECO silver paste, the following components are included according to 100% by mass percentage: 88-90 wt% silver powder, 1.5-3.5 wt% glass powder and 7-9 wt% organic carrier. The glass powder includes anti-ultraviolet nano-oxide. The application improves the contact performance of the silver paste and a silicon wafer, improves the conductive performance of the electrode, and takes into account the efficiency, reliability and long-term stability.

Description

Technical Field

[0001] This invention relates to the field of solar cells, and in particular to a front-side LECO silver paste, its preparation method, and an electrode. Background Technology

[0002] Metamaterial solar cells, as core components in the clean energy field, have conversion efficiency and long-term reliability as key objectives for technological iteration in the industry. In recent years, N-type TOPCon (Tunnel Oxide Passivated Contact) solar cells have become the mainstream development direction of high-efficiency photovoltaic technology due to the unique advantages of passivated contact technology. Among them, TOPCon cells with high sheet resistance design have attracted much attention due to their significant performance improvement.

[0003] TOPCon high sheet resistance solar cells combine a high sheet resistance design (emitter sheet resistance ≥120 Ω / sq) with passivation contact technology, offering multiple outstanding advantages: high potential conversion efficiency, with laboratory efficiency exceeding 26% and mass production efficiency reaching 24%-25.5%, significantly higher than the 22%-23% of traditional PERC cells; excellent passivation structure formed on the back side by an ultra-thin SiO2 layer (1-2nm) and a doped polycrystalline silicon layer, resulting in a surface recombination rate as low as 1-5 cm / s, which, combined with the full back-side contact design, significantly reduces carrier recombination losses; strong bifacial power generation capability (bifaciality ≥85%), smaller power decay at high temperatures (temperature coefficient approximately -0.30% / °C), and excellent resistance to light-induced degradation (LID) and electro-induced degradation (LeTID) on the N-type silicon substrate, with an annual degradation rate as low as 0.4% and first-year degradation <1%; at the same time, this technology is partially compatible with existing PERC production lines, and technology iteration can be achieved by adding LPCVD / PECVD equipment, making the modification cost relatively controllable.

[0004] However, high sheet resistance TOPCon cells still face many challenges in industrialization: at the process level, the thickness of the tunneling oxide layer needs to be precisely controlled within 1-2nm, the uniformity of polycrystalline silicon doping is strictly required, and process fluctuations can easily lead to passivation failure or increased contact resistance; at the cost level, the cost of the N-type silver paste used for it is 10-15% higher than that of PERC silver paste, and the investment in new equipment further increases the initial investment; in addition, the cells are sensitive to the thickness of the silicon wafer (usually ≥150μm), which limits the application of thin wafers, and the long-term stability of the ultrathin SiO2 layer in a humid and hot environment also needs more data verification.

[0005] As a key component of solar cells, the electrodes' conductivity, contact reliability, and long-term stability directly affect the overall performance of the cell. Existing front-side silver pastes adapted for high sheet resistance TOPCon cells are prone to problems such as silver particle oxidation and organic carrier aging in complex outdoor environments (especially under humid, hot, and high-irradiation conditions). This leads to increased electrode resistivity, discoloration, and decreased adhesion, severely impacting the lifespan and power generation efficiency of the cell module. Summary of the Invention

[0006] In view of this, the purpose of the present invention is to provide a front-side LECO silver paste and its preparation method and electrode, which aims to overcome the shortcomings of the above-mentioned background technology, improve the contact performance between the silver paste and the silicon wafer, improve the conductivity of the electrode, and take into account efficiency, reliability and long-term stability.

[0007] The present invention provides a front-side LECO silver paste, which comprises, by weight percentage (100%), the following components: 88-90 wt% silver powder, 1.5-3.5 wt% glass powder, and 7-9 wt% organic carrier; wherein the glass powder comprises UV-resistant nano-oxide.

[0008] Furthermore, the glass powder, based on a molar percentage of 100%, comprises the following components: 15-25 mol% PbO, 25-50 mol% B2O3, 10-15 mol% Bi2O3, 5-10 mol% SiO2, 10-15 mol% Al2O3, 10-15 mol% BaO, and 2-24 mol% UV-resistant nano-oxides.

[0009] Furthermore, the UV-resistant nano-oxide includes at least one of nano-ZnO, nano-TiO2, and nano-CeO2.

[0010] Furthermore, the UV-resistant nano-oxide comprises nano-ZnO, nano-TiO2, and nano-CeO2, with a molar ratio of (2-8):(2-8):(2-8), and the total molar number of nano-ZnO, nano-TiO2, and nano-CeO2 accounts for 2-24 mol of the glass powder.

[0011] Furthermore, the molar ratio of nano-ZnO, nano-TiO2, and nano-CeO2 is 4:6:2.

[0012] Furthermore, the silver powder is spherical silver powder, and the tap density of the spherical silver powder is 6-7 g / cm³, the specific surface area is 0.5-0.8 m² / g, the particle size D10 is 0.2-0.5 μm, the particle size D50 is 1.1-1.7 μm, the particle size D90 is 2-4 μm, and the burn-off is 0.2-0.8%.

[0013] Furthermore, the organic carrier comprises, by weight percentage (100%), the following components: 25-50 wt% solvent, 45-65 wt% resin, and 5-15 wt% additives.

[0014] Further, the solvent includes at least one of diethylene glycol butyl ether acetate and diethylene glycol dibutyl ether; the resin includes at least one of cellulose acetate butyrate, SEBS resin, and polyvinyl butyral; and the additive includes at least one of dimethyl silicone oil and polyesteramine dispersant.

[0015] The present invention also provides a method for preparing the above-described front-side LECO silver paste, comprising the following steps: Mix silver powder, glass powder, and organic carrier according to the set content; The above mixture is ground and mixed evenly using a three-roll mill to obtain the desired front-side LECO silver paste.

[0016] The present invention also provides an electrode, which is formed by printing the aforementioned front-side LECO silver paste onto the surface of a battery cell, followed by sintering and laser treatment.

[0017] The beneficial effects of this invention are as follows: By introducing anti-ultraviolet nano-oxides into glass powder and working synergistically with LECO laser-optimized contact technology, the nano-oxides reduce the photodegradation of polymer binders caused by ultraviolet rays by absorbing or reflecting ultraviolet rays, inhibit the oxidation of silver particles and the aging of organic carriers, and solve problems such as increased electrode resistivity, discoloration and decreased adhesion under high radiation and humid heat environments, thus extending the outdoor service life of the components. Detailed Implementation

[0018] This invention provides a front-side LECO silver paste, which, by weight percentage (100%), comprises the following components: 88-90 wt% silver powder, 1.5-3.5 wt% glass powder, and 7-9 wt% organic carrier; wherein the glass powder includes UV-resistant nano-oxides. This invention, by introducing UV-resistant nano-oxides into the glass powder, works synergistically with LECO laser-optimized contact technology. The nano-oxides absorb or reflect ultraviolet light, reducing UV-induced photodegradation of the polymer binder, inhibiting silver particle oxidation and organic carrier aging, and solving problems such as increased electrode resistivity, discoloration, and decreased adhesion under high radiation and humid conditions, thus extending the outdoor lifespan of the module. Specifically, the silver powder can be in the following proportions: 88 wt%, 88.5 wt%, 89 wt%, 89.5 wt%, or 90 wt%; the glass powder can be in the following proportions: 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, or 3.5 wt%; and the organic carrier can be in the following proportions: 7 wt%, 7.5 wt%, 8 wt%, 8.5 wt%, or 9 wt%.

[0019] Furthermore, the glass powder, based on a 100% molar percentage, comprises the following components: 15-25 mol% PbO, 25-50 mol% B₂O₃, 10-15 mol% Bi₂O₃, 5-10 mol% SiO₂, 10-15 mol% Al₂O₃, 10-15 mol% BaO, and 2-24 mol% UV-resistant nano-oxides. B₂O₃, as a glass network forger, combined with PbO and Bi₂O₃, controls the melting point of the glass powder within a suitable range (matching the sintering process window of TOPCon cells), ensuring sufficient melting of the glass powder during sintering and achieving good ohmic contact between the electrode and the cell (silicon wafer). SiO₂, Al₂O₃, and BaO synergistically enhance the chemical stability and mechanical strength of the glass phase, preventing cracking of the glass layer after sintering or excessive reaction with the silicon wafer, thus protecting the tunneling oxide layer of the TOPCon cell from damage. The UV-resistant nano-oxides form a stable bond with the glass phase, which not only does not affect the melting characteristics and bonding function of the glass powder, but also, through the UV-resistant properties of the nano-oxides, inhibits the photodegradation of the organic carrier and the oxidation of silver particles in the long term, thus extending the outdoor service life of the electrode. The components in the glass powder, such as PbO, B2O3, Bi2O3, SiO2, Al2O3, and BaO, can be directly added oxides or substances obtained by decomposition during the glass powder manufacturing process. Carbonates or complexes of the corresponding oxides can be selected; for example, BaCO3 can be chosen to correspond to BaO. Among them, PbO can be 15mol%, 18mol%, 20mol%, 22mol%, 25mol%, B2O3 can be 25mol%, 30mol%, 35mol%, 40mol%, 45mol%, 50mol%, Bi2O3 can be 10mol%, 12mol%, 14mol%, 15mol%, SiO2 can be 5mol%, 6mol%, 8mol%, 10mol%, Al2O3 can be 10mol%, 12mol%, 14mol%, 15mol%, BaO can be 10mol%, 12mol%, 14mol%, 15mol%, and anti-UV nano-oxides can be 2mol%, 8mol%, 14mol%, 20mol%, 24mol%; not all of them are listed here.

[0020] Furthermore, the UV-resistant nano-oxides include at least one of nano-ZnO, nano-TiO2, and nano-CeO2. Existing technologies use micron-scale oxides, whose function is limited to the chemical properties of the bulk phase. This invention creatively employs nanoscale (typically 1-100 nm) oxides. At this scale, the material exhibits significant surface and quantum size effects, resulting in a qualitative leap in its UV absorption and scattering capabilities, transforming it from a "glass network component" into a highly efficient "UV protectant."

[0021] Furthermore, the UV-resistant nano-oxides include nano-ZnO, nano-TiO2, and nano-CeO2, with a molar ratio of (2-8):(2-8):(2-8), and the total molar number of nano-ZnO, nano-TiO2, and nano-CeO2 accounts for 2-24 mol% of the glass powder. Through the combination of these three nano-oxides, a wider range of UV band (UVA, UVB) coverage can be achieved. Through this combination, nano-CeO2 can suppress the photocatalytic side effects of nano-TiO2 (avoiding the photolysis of the organic carrier by TiO2), while nano-ZnO (mainly absorbs UVA, 320-400nm) and nano-TiO2 (strongly absorbs UVB, 280-320nm) provide strong basic UV shielding capabilities covering different bands. The three form a synergistic protection system of "physical shielding + chemical passivation," which cannot be achieved by any other combination of one or two nano-oxides. Synergistic effects may occur between different oxides, making the composite anti-UV effect better than that of a single oxide.

[0022] Furthermore, the molar ratio of nano-ZnO, nano-TiO2, and nano-CeO2 is 4:6:2.

[0023] Furthermore, the silver powder is spherical, with a tap density of 6-7 g / cm³, a specific surface area of ​​0.5-0.8 m² / g, a particle size D10 of 0.2-0.5 μm, a particle size D50 of 1.1-1.7 μm, a particle size D90 of 2-4 μm, and a burn-off of 0.2-0.8%.

[0024] Furthermore, the organic carrier, by weight percentage (100%), comprises the following components: 25-50 wt% solvent, 45-65 wt% resin, and 5-15 wt% additives. The resin provides sufficient adhesion to the silver paste, ensuring a firm bond between the silver powder and glass powder particles after printing, preventing electrode detachment during drying. Simultaneously, the resin acts as a film-forming agent, enabling the silver paste to form a uniform film and improving printing accuracy. The solvent content sufficiently dissolves the resin, adjusting the silver paste to a suitable viscosity, ensuring leveling and continuity during printing, and preventing defects such as broken grids and burrs. The solvent's evaporation rate matches the resin's film-forming rate, reducing pinholes and bubbles in the electrodes after drying. The additive content, without affecting the carrier's basic performance, further optimizes the silver paste's processing performance and stability through synergistic functions (such as dispersion, lubrication, and defoaming), laying the foundation for excellent electrode performance. The solvent, resin, and additives (dispersants, lubricants, defoamers, etc.) synergistically constitute the organic carrier, whose comprehensive performance meets the requirements of high dispersibility, controllable thermal decomposition, and laser process compatibility for silver paste.

[0025] Furthermore, the solvent includes at least one of diethylene glycol butyl ether acetate and diethylene glycol dibutyl ether; the resin includes at least one of cellulose acetate butyrate, SEBS resin, and polyvinyl butyral; and the additive includes at least one of dimethyl silicone oil and polyesteramine dispersant.

[0026] The present invention also provides a method for preparing the above-mentioned front-side LECO silver paste, comprising the following steps: Mix silver powder, glass powder, and organic carrier according to the set content; The above mixture is ground and mixed evenly using a three-roll mill to obtain the desired front-side LECO silver paste.

[0027] Specifically, the following steps are adopted: (1) Add silver powder, glass powder and organic carrier to the mixing tank according to the formula, perform preliminary manual mixing first, and then centrifuge and stir.

[0028] (2) Use a three-roll mill for mixing, set the speed to 300 rpm. First step, mix once with the initial roller gap of 70 μm and the final roller gap of 50 μm; second step, mix once with the initial roller gap of 50 μm and the final roller gap of 30 μm; third step, mix once with the initial roller gap of 30 μm and the final roller gap of 20 μm; fourth step, mix once with the initial roller gap of 30 μm and the final roller gap of 20 μm; fifth step, mix once with the initial roller gap of 20 μm and the final roller gap of 10 μm; sixth step, mix once with the initial roller gap of 10 μm and the final roller gap of 5 μm to make the dispersion uniform and obtain the finished LECO silver paste on the front side.

[0029] This invention also provides an electrode, which is formed by printing the aforementioned front-side LECO silver paste onto the surface of a solar cell, followed by sintering and laser treatment. The front-side LECO silver paste is printed onto a solar cell with a sheet resistance of 500 Ω / sq after oxidation using a narrow-linewidth screen (700 mesh count, 4 μm wire diameter, 10.5 μm yarn thickness, 5 μm film thickness, 7.5 μm aperture). The wet weight is controlled within the range of 30-32 mg. The electrode for a TOPCon solar cell is then formed through sintering and laser treatment. This screen, with its high mesh count and narrow aperture design, is suitable for the fine printing requirements of UV-resistant LECO silver paste, enabling the formation of electrode patterns with narrow linewidths and high consistency. Of course, this front-side LECO silver paste is also suitable for high-efficiency battery technologies such as PERC and HJT.

[0030] The front-side LECO silver paste of this invention is mainly used in the following industries: 1. Photovoltaic Industry (Core Applications) (1) High-efficiency solar cells: suitable for high-efficiency cell technologies such as PERC, TOPCon, and HJT. Their anti-ultraviolet properties can reduce the performance degradation of electrodes under long-term outdoor ultraviolet radiation and extend the life of the module (especially in high-ultraviolet regions such as plateaus and deserts).

[0031] (2) Bifacial power generation module: The UV resistance of the front electrode can improve the overall reliability of both sides of the bifacial module.

[0032] (3) BIPV (Building Integrated Photovoltaics): When used as a building facade material, it needs to withstand ultraviolet rays for a long time. Anti-ultraviolet silver paste can reduce maintenance costs and improve aesthetics.

[0033] 2. Outdoor electronic equipment (1) LED display screen / outdoor electronic sign: used for conductive circuits in high ultraviolet environments to prevent display failure caused by electrode aging.

[0034] (2) Intelligent transportation systems: such as solar-powered traffic lights and electronic road signs, which need to operate stably in harsh environments for a long time.

[0035] 3. Automotive electronics (1) Photovoltaic roof of new energy vehicle: The solar cells integrated on the roof need to resist ultraviolet rays and temperature changes. Anti-ultraviolet silver paste can improve durability.

[0036] (2) On-board sensors / circuits: used in engine compartments or external electronic components to protect conductive lines from ultraviolet radiation.

[0037] 4. Aerospace and Satellite Technology (1) Space photovoltaic system: Satellite and space station solar panels are exposed to high-intensity cosmic rays (including ultraviolet rays), and anti-ultraviolet silver paste can enhance stability in extreme environments.

[0038] (2) High-altitude drones: Long-term high-altitude flight requires coping with strong ultraviolet radiation, and the weather resistance of silver paste can ensure the equipment's endurance.

[0039] 5. Flexible electronics and wearable devices (1) Flexible solar cells: used in foldable devices or wearable power generation devices, combining flexibility and UV resistance to adapt to complex usage environments.

[0040] (2) Smart textiles: Outdoor clothing or equipment with integrated conductive circuits that need to withstand sun exposure and repeated bending.

[0041] 6. High-end consumer electronics (1) Outdoor smart devices: such as solar-powered smartwatches, drones, etc., to improve the reliability of circuits under ultraviolet light.

[0042] (2) High-precision circuit printing: miniaturized devices that need to be exposed to light for a long time (such as IoT sensors).

[0043] The present invention will be further illustrated below with reference to specific embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0044] The LECO silver paste is a conductive metal paste containing silver powder, glass powder, and an organic carrier. The silver pastes in the following embodiments are all prepared from 89 wt% silver powder, 3 wt% glass powder, and 8 wt% organic carrier. The silver powder is a single polycrystalline spherical silver powder with a tap density of 6.32 g / cm³, a specific surface area of ​​0.50 m² / g, a particle size D10 of 0.36 μm, a particle size D50 of 1.52 μm, a particle size D90 of 2.47 μm, and a burn-off rate of 0.58%. The organic carrier component consists of 50 wt% resin (composed of 30 wt% cellulose acetate butyrate, 10 wt% SEBS resin, and 10 wt% polyvinyl butyral), 40 wt% solvent (composed of 20 wt% diethylene glycol butyl ether acetate and 20 wt% diethylene glycol dibutyl ether), and 10 wt% additives (composed of 8 wt% dimethyl silicone oil and 2 wt% polyesteramine dispersant). The single glass powder composition consists of 15-25 mol% PbO, 25-50 mol% B2O3, 10-15 mol% Bi2O3, 5-10 mol% SiO2, 10-15 mol% Al2O3, 10-15 mol% BaCO3, 2-8 mol% nano ZnO, 2-8 mol% nano TiO2, and 2-8 mol% CeO2.

[0045] Silver powder, glass powder, and organic carrier are added to the mixing tank according to the formula. First, they are manually mixed until no dry powder remains using a scraper or stirring paddle, then centrifuged. The silver powder, glass powder, and organic carrier are then mixed using a three-roll mill at 300 rpm. The mixing steps are as follows: Step 1: Initial roller gap 70µm, final roller gap 50µm, mix once; Step 2: Initial roller gap 50µm, final roller gap 30µm, mix once; Step 3: Initial roller gap 30µm, final roller gap 20µm, mix once; Step 4: Initial roller gap 30µm, final roller gap 20µm, mix once; Step 5: Initial roller gap 20µm, final roller gap 10µm, mix once; Step 6: Initial roller gap 10µm, final roller gap 5µm, mix once to ensure uniform dispersion and obtain the finished front-side LECO silver paste.

[0046] Example 1 (1) 15 mol% PbO, 48 mol% B2O3, 10 mol% Bi2O3, 5 mol% SiO2, 10 mol% Al2O3, 10 mol% BaCO3, and 2 mol% nano ZnO were used to prepare glass powder.

[0047] (2) Add 89wt% silver powder, 3wt% glass powder and 8wt% organic carrier to the mixing tank according to the formula. First, perform preliminary manual mixing, and then use a centrifuge to centrifuge and stir.

[0048] (3) Use a three-roll mill to mix the slurry, setting the speed to 300 rpm. First step, mix once with the initial roller gap of 70 μm and the final roller gap of 50 μm; second step, mix once with the initial roller gap of 50 μm and the final roller gap of 30 μm; third step, mix once with the initial roller gap of 30 μm and the final roller gap of 20 μm; fourth step, mix once with the initial roller gap of 30 μm and the final roller gap of 20 μm; fifth step, mix once with the initial roller gap of 20 μm and the final roller gap of 10 μm; sixth step, mix once with the initial roller gap of 10 μm and the final roller gap of 5 μm to achieve uniform dispersion and obtain the finished LECO silver paste on the front side.

[0049] (4) The front-side LECO silver paste was printed onto the TOPCon solar cell with a sheet resistance of 500Ω / sq after oxidation using a 700-4-10.5-5-7.5μm narrow linewidth screen printing plate. The wet weight was controlled within the range of 30-32mg. The electrodes of the TOPCon solar cell were formed by sintering and laser.

[0050] Example 2 (1) Referring to Example 1, only the glass powder composition was adjusted while the others remained unchanged to obtain the corresponding front-side LECO silver paste.

[0051] (2) 20 mol% PbO, 41 mol% B2O3, 10 mol% Bi2O3, 5 mol% SiO2, 10 mol% Al2O3, 10 mol% BaCO3, and 4 mol% nano ZnO were used to prepare glass powder.

[0052] (3) The process of preparing the front LECO silver paste as an electrode is the same as in Example 1.

[0053] Example 3 (1) Referring to Example 1, only the glass powder composition was adjusted while the others remained unchanged to obtain the corresponding front-side LECO silver paste.

[0054] (2) 18 mol% PbO, 41 mol% B2O3, 10 mol% Bi2O3, 5 mol% SiO2, 10 mol% Al2O3, 10 mol% BaCO3, and 6 mol% nano ZnO were prepared into glass powder.

[0055] (3) The process of preparing the front LECO silver paste as an electrode is the same as in Example 1.

[0056] Example 4 (1) Referring to Example 1, only the glass powder composition was adjusted while the others remained unchanged to obtain the corresponding front-side LECO silver paste.

[0057] (2) 18 mol% PbO, 39 mol% B2O3, 10 mol% Bi2O3, 5 mol% SiO2, 10 mol% Al2O3, 10 mol% BaCO3, and 8 mol% nano ZnO were used to prepare glass powder.

[0058] (3) The process of preparing the front LECO silver paste as an electrode is the same as in Example 1.

[0059] Example 5 (1) Referring to Example 1, only the glass powder composition was adjusted while the others remained unchanged to obtain the corresponding front-side LECO silver paste.

[0060] (2) 18 mol% PbO, 41 mol% B2O3, 10 mol% Bi2O3, 5 mol% SiO2, 10 mol% Al2O3, 10 mol% BaCO3, 4 mol% nano ZnO, and 2 mol% nano TiO2 were used to prepare glass powder.

[0061] (3) The process of preparing the front LECO silver paste as an electrode is the same as in Example 1.

[0062] Example 6 (1) Referring to Example 1, only the glass powder composition was adjusted while the others remained unchanged to obtain the corresponding front-side LECO silver paste.

[0063] (2) 18 mol% PbO, 39 mol% B2O3, 10 mol% Bi2O3, 5 mol% SiO2, 10 mol% Al2O3, 10 mol% BaCO3, 4 mol% nano ZnO, and 4 mol% nano TiO2 were used to prepare glass powder.

[0064] (3) The process of preparing the front LECO silver paste as an electrode is the same as in Example 1.

[0065] Example 7 (1) Referring to Example 1, only the glass powder composition was adjusted while the others remained unchanged to obtain the corresponding front-side LECO silver paste.

[0066] (2) 18 mol% PbO, 37 mol% B2O3, 10 mol% Bi2O3, 5 mol% SiO2, 10 mol% Al2O3, 10 mol% BaCO3, 4 mol% nano ZnO, and 6 mol% nano TiO2 were used to prepare glass powder.

[0067] (3) The process of preparing the front LECO silver paste as an electrode is the same as in Example 1.

[0068] Example 8 (1) Referring to Example 1, only the glass powder composition was adjusted while the others remained unchanged to obtain the corresponding front-side LECO silver paste.

[0069] (2) 18 mol% PbO, 35 mol% B2O3, 10 mol% Bi2O3, 5 mol% SiO2, 10 mol% Al2O3, 10 mol% BaCO3, 4 mol% nano ZnO, and 8 mol% nano TiO2 were used to prepare glass powder.

[0070] (3) The process of preparing the front LECO silver paste as an electrode is the same as in Example 1.

[0071] Example 9 (1) Referring to Example 1, only the glass powder composition was adjusted while the others remained unchanged to obtain the corresponding front-side LECO silver paste.

[0072] (2) 18 mol% PbO, 35 mol% B2O3, 10 mol% Bi2O3, 5 mol% SiO2, 10 mol% Al2O3, 10 mol% BaCO3, 4 mol% nano ZnO, 6 mol% nano TiO2, and 2 mol% nano CeO2 were prepared into glass powder.

[0073] (3) The process of preparing the front LECO silver paste as an electrode is the same as in Example 1.

[0074] Example 10 (1) Referring to Example 1, only the glass powder composition was adjusted while the others remained unchanged to obtain the corresponding front-side LECO silver paste.

[0075] (2) 18 mol% PbO, 33 mol% B2O3, 10 mol% Bi2O3, 5 mol% SiO2, 10 mol% Al2O3, 10 mol% BaCO3, 4 mol% nano ZnO, 6 mol% nano TiO2, and 4 mol% nano CeO2 were prepared into glass powder.

[0076] (3) The process of preparing the front LECO silver paste as an electrode is the same as in Example 1.

[0077] Example 11 (1) Referring to Example 1, only the glass powder composition was adjusted while the others remained unchanged to obtain the corresponding front-side LECO silver paste.

[0078] (2) 18 mol% PbO, 31 mol% B2O3, 10 mol% Bi2O3, 5 mol% SiO2, 10 mol% Al2O3, 10 mol% BaCO3, 4 mol% nano ZnO, 6 mol% nano TiO2, and 6 mol% nano CeO2 were prepared into glass powder.

[0079] (3) The process of preparing the front LECO silver paste as an electrode is the same as in Example 1.

[0080] Example 12 (1) Referring to Example 1, only the glass powder composition was adjusted while the others remained unchanged to obtain the corresponding front-side LECO silver paste.

[0081] (2) 18 mol% PbO, 29 mol% B2O3, 10 mol% Bi2O3, 5 mol% SiO2, 10 mol% Al2O3, 10 mol% BaCO3, 4 mol% nano ZnO, 6 mol% nano TiO2, and 8 mol% nano CeO2 were prepared into glass powder.

[0082] (3) The process of preparing the front LECO silver paste as an electrode is the same as in Example 1.

[0083] Example 13 (1) Referring to Example 1, only the glass powder composition was adjusted while the others remained unchanged to obtain the corresponding front-side LECO silver paste.

[0084] (2) 18 mol% PbO, 43 mol% B2O3, 10 mol% Bi2O3, 5 mol% SiO2, 10 mol% Al2O3, 10 mol% BaCO3, and 4 mol% nano TiO2 were used to prepare glass powder.

[0085] (3) The process of preparing the front LECO silver paste as an electrode is the same as in Example 1.

[0086] Example 14 (1) Referring to Example 1, only the glass powder composition was adjusted while the others remained unchanged to obtain the corresponding front-side LECO silver paste.

[0087] (2) 18 mol% PbO, 43 mol% B2O3, 10 mol% Bi2O3, 5 mol% SiO2, 10 mol% Al2O3, 10 mol% BaCO3, and 4 mol% nano CeO2 were used to prepare glass powder.

[0088] (3) The process of preparing the front LECO silver paste as an electrode is the same as in Example 1.

[0089] Example 15 (1) Referring to Example 1, only the glass powder composition was adjusted while the others remained unchanged to obtain the corresponding front-side LECO silver paste.

[0090] (2) 18 mol% PbO, 35 mol% B2O3, 10 mol% Bi2O3, 5 mol% SiO2, 10 mol% Al2O3, 10 mol% BaCO3, 4 mol% nano ZnO, 4 mol% nano TiO2, and 4 mol% nano CeO2 were prepared into glass powder.

[0091] (3) The process of preparing the front LECO silver paste as an electrode is the same as in Example 1.

[0092] Example 16 (1) Referring to Example 1, only the glass powder composition was adjusted while the others remained unchanged to obtain the corresponding front-side LECO silver paste.

[0093] (2) 18 mol% PbO, 31 mol% B2O3, 10 mol% Bi2O3, 5 mol% SiO2, 10 mol% Al2O3, 10 mol% BaCO3, 4 mol% nano ZnO, 8 mol% nano TiO2, and 4 mol% nano CeO2 were prepared into glass powder.

[0094] (3) The process of preparing the front LECO silver paste as an electrode is the same as in Example 1.

[0095] Comparative Example 1: (1) Referring to Example 1, only the glass powder composition was adjusted while the others remained unchanged to obtain the corresponding front-side LECO silver paste.

[0096] (2) Prepare glass powder from 15 mol% PbO, 50 mol% B2O3, 10 mol% Bi2O3, 5 mol% SiO2, 10 mol% Al2O3 and 10 mol% BaCO3.

[0097] (3) The process of preparing the front LECO silver paste as an electrode is the same as in Example 1.

[0098] The component ratios of each embodiment and comparative example are shown in Table 1, and the electrical performance of the corresponding electrode products is shown in Table 2. Here, Eta after irradiation represents the data of the corresponding electrode product after 7 days of UV irradiation. The UV irradiation dose is higher than that in the natural outdoor environment, constituting a stress-enhancing test. Its purpose is not to simulate the absolute lifespan and degradation value of the battery module under real outdoor conditions, but rather to amplify the performance differences of different silver paste formulations under a unified and stringent benchmark condition, thereby efficiently and clearly screening out the formulation scheme with the best UV resistance. To further clarify, this test directly evaluates the performance of the silver paste itself under UV stress. In actual solar cell modules, the electrodes made of silver paste are also protected by encapsulation materials (such as EVA, POE), cover glass, and other components, which themselves also possess a certain degree of UV resistance, collectively ensuring the overall long-term reliability of the module. Therefore, the degradation rate observed in this test should be understood as a measure of the inherent weather resistance of the silver paste material itself, rather than a prediction of the final module product lifespan.

[0099] Table 1. Component ratios of each embodiment and comparative example

[0100] Table 2 Electrical properties of the corresponding electrode products

[0101] Based on the component ratio of glass powder in Table 1 and the performance test table in Table 2, the following conclusions can be drawn: (1) Significant improvement of the anti-aging performance of silver paste by anti-UV nano-oxides: Introducing nano-ZnO, nano-TiO2, and nano-CeO2 (especially the combination of the three) into glass powder can significantly reduce the efficiency decay rate of silver paste after UV irradiation. For example, Example 9 uses a combination of nano-ZnO, nano-TiO2, and nano-CeO2 in a molar ratio of 4:6:2, and its decay rate is only 20.81%, which is much lower than the comparative example without the addition of anti-UV nano-oxides (decay rate of 80.53%), and also significantly better than the examples with single nano-oxides (such as Example 1 with only nano-ZnO added, decay rate of 77.02%). This shows that the synergistic effect of the combination of anti-UV nano-oxides can effectively inhibit the oxidation of silver particles and the aging of organic carriers, and improve the long-term UV stability of silver paste.

[0102] Meanwhile, the core value of the "attenuation rate" shown in Table 2 lies in the horizontal comparison between formulations. The significant attenuation exhibited by Comparative Example 1 (without UV-resistant nano-oxides) confirms the inherent vulnerability of silver paste to extreme UV stress without protection; while the attenuation rates shown in the various embodiments of the present invention, especially the preferred embodiments, are far lower than those of the comparative example. Example 9 uses a compound scheme with a molar ratio of nano-ZnO, nano-TiO2, and nano-CeO2 of 4:6:2, and its absolute attenuation rate is reduced by 59.72 percentage points compared to Comparative Example 1 (from 80.53% to 20.81%). In terms of relative improvement, the attenuation rate reduction is as high as approximately 74%. This strongly demonstrates that introducing UV-resistant nano-oxides into glass powder can fundamentally and effectively improve the UV resistance of the silver paste material itself.

[0103] (2) Synergistic optimization of electrical performance and anti-aging performance: The introduction of anti-UV nano-oxides did not have a negative impact on the initial electrical performance of the silver paste. The parameters of open circuit voltage (Uoc), short circuit current (Isc), fill factor (FF) and series resistance (Rser) of Example 9 are all at excellent levels (e.g., FF reaches 86.29% and Rser is only 0.00089Ω), while also having the lowest decay rate. This achieves synergistic optimization of "high initial efficiency" and "long life anti-aging", which is fully compatible with the performance requirements of electrode materials for high sheet resistance TOPCon solar cells.

[0104] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the appended claims.

Claims

1. A front-side LECO silver paste, characterized in that, The front-side LECO silver paste, by weight percentage (100%), comprises the following components: 88-90 wt% silver powder, 1.5-3.5 wt% glass powder, and 7-9 wt% organic carrier; wherein the glass powder includes UV-resistant nano-oxides. The total raw materials of the glass powder, calculated as 100% by mole percentage, include the following components: 15-25 mol% PbO, 25-50 mol% B2O3, 10-15 mol% Bi2O3, 5-10 mol% SiO2, 10-15 mol% Al2O3, 10-15 mol% BaO, and 2-24 mol% UV-resistant nano-oxides. The UV-resistant nano-oxides include nano-ZnO, nano-TiO2, and nano-CeO2, with a molar ratio of 4:(6-8):(2-8) for nano-ZnO, nano-TiO2, and nano-CeO2.

2. The front-side LECO silver paste as described in claim 1, characterized in that, The total molar amount of nano ZnO, nano TiO2 and nano CeO2 accounts for 2-24 mol of the total raw materials of the glass powder.

3. The front-side LECO silver paste as described in claim 2, characterized in that, The molar ratio of nano ZnO, nano TiO2 and nano CeO2 is 4:6:

2.

4. The front-side LECO silver paste as described in claim 1, characterized in that, The silver powder is spherical, with a tap density of 6-7 g / cm³, a specific surface area of ​​0.5-0.8 m² / g, a particle size D10 of 0.2-0.5 μm, a particle size D50 of 1.1-1.7 μm, a particle size D90 of 2-4 μm, and a burn-off of 0.2-0.8%.

5. The front-side LECO silver paste as described in claim 1, characterized in that, The organic carrier comprises, by weight percentage (100%), the following components: 25-50 wt% solvent, 45-65 wt% resin, and 5-15 wt% additives.

6. The front-side LECO silver paste as described in claim 5, characterized in that, The solvent includes at least one of diethylene glycol butyl ether acetate and diethylene glycol dibutyl ether; the resin includes at least one of cellulose acetate butyrate, SEBS resin, and polyvinyl butyral; and the additive includes dimethyl silicone oil.

7. A method for preparing the front-side LECO silver paste as described in any one of claims 1-6, characterized in that, Includes the following processes: Mix silver powder, glass powder, and organic carrier according to the set content; The above mixture is ground and mixed evenly using a three-roll mill to obtain the desired front-side LECO silver paste.

8. An electrode, characterized in that, The electrode is formed by printing the front-side LECO silver paste as described in any one of claims 1-6 onto the surface of the battery cell, followed by sintering and laser treatment.

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