A glass powder for a top con high sheet resistance battery front side fine grid paste suitable for leco process and a preparation method thereof

Abstract

The application discloses a glass powder for a TOPCon high-sheets-resistance battery positive surface fine grid paste suitable for a LECO process and a preparation method thereof, and the raw material composition comprises the following components in terms of molar percentage: PbO 9.5-14.5mol%, B2O3 49.0-59.0mol%, GeO2 1.2-4.2mol%, Al(OH)3 4.5-8.5mol%, BaO 4.2-7.8mol%, Nd2O3 0.3-0.9mol%, and BeO 18.0-25.0mol%. The application realizes the synergistic optimization of the reduction of the contact resistance and the improvement of the open-circuit voltage by precisely controlling the formula components and the proportion, mainly utilizing Al(OH)3 to optimize the contact performance and BeO to improve the open-circuit voltage, and is suitable for the performance requirement of the high-sheets-resistance TOPCon battery and guarantees the efficient and stable operation of the battery.

Description

Technical Field

[0001] This invention relates to the field of photovoltaic cell technology, specifically to a glass powder for the front grid paste of TOPCon (tunneling oxide passivated contact) high sheet resistance cells suitable for LECO (laser-enhanced contact optimization) process, which can effectively improve cell contact performance and open-circuit voltage, ensuring efficient and stable cell operation. Background Technology

[0002] TOPCon cells, as a highly promising high-efficiency crystalline silicon cell technology in the current photovoltaic field, employ a passivated contact structure composed of ultra-thin silicon oxide and heavily doped polycrystalline silicon. This significantly suppresses minority carrier recombination at the metal-silicon interface, achieving high carrier transport efficiency, with a theoretical limit approaching the theoretical upper limit of crystalline silicon solar cells. Among these, high sheet resistance TOPCon cells further reduce surface recombination losses by optimizing the doping concentration of the front emitter; however, the formation of an ohmic contact between the front fine grid paste and the emitter becomes significantly more difficult, becoming a key bottleneck restricting the improvement of cell efficiency.

[0003] LECO laser technology, as a core technology for optimizing the metal-semiconductor contact in TOPCon batteries, can promote contact formation between the metal electrode and the silicon substrate through laser-induced carrier injection, significantly reducing contact resistance. However, existing glass powder formulations generally suffer from two major problems when adapted to LECO technology and high sheet resistance TOPCon battery front-side grid paste: First, poor contact performance; the glass powder struggles to form a uniform and stable contact interface during laser sintering, easily leading to high contact resistance and increased carrier transport losses. Second, limited open-circuit voltage improvement; insufficient compositional matching of the glass powder can damage the integrity of the passivation layer on the front side of the battery, increasing interface recombination losses and resulting in a lower open-circuit voltage (V). o c) Unable to reach the ideal level.

[0004] In existing technologies, some formulations improve contact performance by adding aluminum-based compounds, but these often use oxides such as alumina, which have insufficient reactivity in the LECO process, making it difficult to effectively promote the formation of silver-silicon contact channels. Meanwhile, optimization of open-circuit voltage largely relies on rare-earth element doping, which has limited effectiveness and high cost. Furthermore, the application of beryllium compounds in glass powders mainly focuses on adjusting refractive index and thermal stability; no technology has yet clearly defined their targeted role in improving the open-circuit voltage of high sheet resistance TOPCon cells, and synergistic optimization and matching between aluminum-based and beryllium-based compounds have not been achieved.

[0005] Therefore, developing a glass powder formulation that is compatible with the LECO process and can simultaneously optimize the front contact performance and open-circuit voltage of high sheet resistance TOPCon cells has become an urgent need in the current photovoltaic technology field. Summary of the Invention

[0006] To address the aforementioned problems in existing technologies, this invention proposes a glass powder for the front-side fine grid paste of TOPCon high sheet resistance batteries suitable for LECO processes and its preparation method. This invention achieves synergistic optimization of contact resistance reduction and open-circuit voltage increase by precisely controlling the formulation composition and ratio, focusing on utilizing Al(OH)3 to optimize contact performance and BeO to improve open-circuit voltage. This adapts to the performance requirements of high sheet resistance TOPCon batteries, ensuring efficient and stable battery operation.

[0007] The technical solution of the present invention is as follows: The first objective of this invention is to provide a glass powder for the front-side fine grid paste of a TOPCon high sheet resistance battery suitable for the LECO process. The raw material composition, by molar percentage, is: PbO 9.5~14.5 mol%, B2O3 49.0~59.0 mol%, GeO2 1.2~4.2 mol%, Al(OH)3 4.5~8.5 mol%, BaO 4.2~7.8 mol%, Nd2O3 0.3~0.9 mol%, BeO 18.0~25.0 mol%.

[0008] In one embodiment of the present invention, the particle size of the glass powder is ≤15μm.

[0009] In one embodiment of the present invention, the glass powder, by molar percentage, has the following raw material composition: PbO 11.65 mol%, B2O3 51.31 mol%, GeO 22.73 mol%, Al(OH)3 6.82 mol%, BaO 5.62 mol%, Nd2O3 0.58 mol%, BeO 21.29 mol%.

[0010] In one embodiment of the present invention, the purity of Al(OH)3 is ≥99.99%, and it is dried at 120°C for 2 hours before use; the purity of BeO is ≥99.99%, and the particle size is ≤1μm.

[0011] In one embodiment of the present invention, Al(OH)3 is used as the core component for optimizing contact performance, and its mechanism of action is mainly reflected in the following three aspects: (1) High-temperature decomposition activity regulation: During the LECO laser sintering process, Al(OH)3 undergoes a precise dehydration decomposition reaction (2Al(OH)3→Al2O3+3H2O↑). The trace amount of water vapor generated by this reaction can moderately erode the ultra-thin silicon oxide passivation layer on the front side of the battery, forming a nanoscale contact channel, providing a path for the contact between silver ions and the silicon substrate, while avoiding the damage to the passivation layer caused by excessive erosion. The Al2O3 generated by decomposition has extremely high reactivity and can react with the silver powder and silicon substrate in the slurry to promote the formation of the silver-aluminum-silicon alloy phase and significantly reduce the contact resistance.

[0012] (2) LECO process adaptability optimization: The decomposition temperature of Al(OH)3 is highly matched with the temperature window of LECO laser sintering (the local high temperature induced by the laser can accurately trigger its decomposition reaction). The decomposition product Al2O3 can suppress the excessive growth of silver grains, ensure the uniformity of the contact interface, and avoid contact resistance fluctuations caused by coarse grains. It is especially suitable for the fine contact requirements of the fine grid on the front side of the high sheet resistance TOPCon battery.

[0013] (3) Synergistic effect: Al(OH)3 can form a stable synergistic system with PbO (9.5~14.5mol%) and B2O3 (49.0~59.0mol%) in the formula within the range of 4.5~8.5mol%, which can effectively reduce the softening temperature of glass powder, allowing the glass phase to flow and spread rapidly during laser sintering, forming a continuous contact interface and further improving contact stability. Even at the boundary value of the range, the contact resistance reduction can still reach more than 15%. Compared with traditional aluminum compounds such as alumina and fixed ratio formulas, it has both performance stability and process adaptability. The contact resistance reduction effect is best when the optimal ratio is 6.82mol% (23.1%).

[0014] In one embodiment of the present invention, BeO, as a key component for improving open-circuit voltage, mainly functions in the following three aspects: (1) Passivation layer protection and interface recombination suppression: BeO has excellent chemical stability and insulation properties in the range of 18.0~25.0 mol%. During the LECO laser sintering process, it can stably form an ultra-thin passivation protective film, covering the silicon substrate surface not occupied by the contact channel, effectively suppressing minority carrier recombination at the metal-silicon interface, reducing the saturation current density, and the open circuit voltage can be increased by 8~13 mV in the range. When the optimal ratio is 21.29 mol%, the passivation protection effect is the best, and the open circuit voltage is increased to 742 mV, which is far superior to the traditional rare earth doped or beryllium-free formulation. Moreover, the range design is adapted to the material error of industrial production, avoiding performance fluctuations caused by slight deviations in the fixed ratio.

[0015] (2) Carrier transport selectivity optimization: The band gap of BeO is highly matched with the band structure of the front emitter of the TOPCon battery, which can realize the efficient transport of majority carriers (holes) while blocking the recombination of minority carriers (electrons), improving the selectivity of carrier transport, and further optimizing the open circuit voltage and fill factor.

[0016] (3) Thermal stability and process compatibility assurance: BeO has good thermal conductivity, which can quickly disperse local heat during laser sintering, avoid silicon substrate damage and passivation layer failure caused by local high temperature, ensure the integrity of the passivation performance of the front side of the battery, provide process assurance for the stable improvement of open circuit voltage, and perfectly match the high temperature and short time sintering characteristics of LECO process.

[0017] In one embodiment of the present invention, B2O3 (49.0~59.0 mol%, preferably 51.31 mol%) serves as a glass forging body, forming the basic framework of the glass powder. This molar range ensures stable formation of the glass phase and suitable fluidity, while adjusting the melting point and viscosity of the glass powder. It provides a stable carrier for Al(OH)3 (4.5~8.5 mol%) and BeO (18.0~25.0 mol%) to play their core roles. The boundary values ​​of the range can still avoid problems such as glass phase crystallization or insufficient fluidity.

[0018] In one embodiment of the present invention, PbO (9.5~14.5 mol%, preferably 11.65 mol%): This molar range can effectively reduce the softening temperature and viscosity of glass powder, improve the wettability of the glass phase, promote the formation of contact interfaces, and optimize the conductivity of glass powder. The performance is stable within the range and can adapt to the slight differences in different batches of raw materials. In one embodiment of the present invention, GeO2 (1.2~4.2 mol%, preferably 2.73 mol%): a trace amount of molar range can effectively improve the chemical stability and refractive index of glass powder, inhibit the crystallization of glass phase, and ensure the long-term stability of the contact interface. The range design avoids the cost increase and performance redundancy caused by excessive addition. In one embodiment of the present invention, BaO (4.2~7.8 mol%, preferably 5.62 mol%): This molar range allows for flexible adjustment of the thermal expansion coefficient of the glass powder, enabling precise matching with the thermal expansion coefficients of the TOPCon battery silicon substrate and silver electrode, reducing interfacial stress after sintering, preventing crack formation, and adapting to the fine-tuning requirements of different process parameters. In one embodiment of the present invention, Nd2O3 (0.3~0.9mol%, preferably 0.58mol%): the narrow molar range design of rare earth doping can optimize the optical performance of glass powder, reduce light reflection loss, and help improve the stability of the contact interface, while avoiding the cost surge and negative performance impact caused by excessive doping, which meets the low cost and high efficiency requirements of the photovoltaic field.

[0019] A second objective of this invention is to provide a method for preparing the aforementioned glass powder, comprising the following steps: (1) Raw material pretreatment: Weigh each component by molar percentage, dry Al(OH)3 to remove water, and pulverize BeO to a particle size ≤1μm; (2) Mixing and grinding: The pretreated raw materials are wet-ground for 2 hours to obtain a uniformly mixed slurry; (3) Drying and granulation: The mixed slurry is spray-dried to obtain particles with a particle size of 50~100μm; (4) Melt quenching: Melt the particles at 1200-1250℃ and hold for 2 hours, then quench them with water to obtain glass fragments; (5) Ultrafine grinding: Dry grind the glass fragments for 4 hours and pass them through a 1000-mesh sieve to obtain the finished glass powder.

[0020] In one embodiment of the present invention, in step (2), wet grinding is carried out in a planetary ball mill, the grinding media is 2mm zirconia balls, the grinding liquid media is pure water, the ball-to-water ratio is 8:1:0.5, and the rotation speed is 300r / min.

[0021] In one embodiment of the present invention, in step (3), the spray drying inlet temperature is 200°C and the outlet temperature is 80°C.

[0022] In one embodiment of the present invention, in step (5), dry grinding is carried out in a planetary ball mill, using 10mm zirconia balls as the grinding media, with a ball-to-material ratio of 2:1 and a rotation speed of 200r / min.

[0023] A third objective of this invention is to provide a TOPCon high sheet resistance cell front grid paste suitable for the LECO process, containing the aforementioned glass powder.

[0024] In one embodiment of the present invention, the TOPCon high sheet resistance cell front grid paste suitable for LECO process, by mass parts, consists of the following raw material composition: 2-3 parts of glass powder, 80-85 parts of silver powder, and 12-18 parts of organic carrier.

[0025] In one embodiment of the present invention, glass powder, silver powder, and organic carrier are mixed in proportion, and after stirring, grinding, and dispersing, a fine grid paste for the front side is prepared. The paste is screen-printed onto the front side of the TOPCon battery, and after drying, it is treated with LECO laser technology (laser intensity 100-150W, scanning speed 50-100mm / s) to finally complete the metallization of the front side of the battery.

[0026] In one embodiment of the present invention, the sheet resistance of the TOPCon high sheet resistance battery is in the range of 100-150Ω / □.

[0027] Beneficial effects: The glass powder of this invention can stably promote the formation of silver-silicon contact channels, reduce contact resistance by more than 15%, completely solve the problem of fine grid contact on the front side of high sheet resistance TOPCon batteries, and ensure efficient carrier transport. The synergistic effect of the components of the glass powder ensures the chemical stability, thermal stability and interface compatibility of the glass powder, reduces the performance degradation during long-term battery operation, and improves battery life. Moreover, the formula does not contain rare precious metals, the raw materials of each component are readily available, the preparation process is simple, and low-cost large-scale production can be achieved, which has extremely high industrial application value.

[0028] The glass powder components of this invention work synergistically to stably form an interfacial passivation protective film, suppress minority carrier recombination, significantly improve open-circuit voltage, and substantially enhance battery efficiency. The melting point and reaction temperature of each component are highly matched with the LECO laser sintering process, enabling rapid and stable contact formation. At the same time, the wide range of material tolerances (±0.5~1.0 mol%) designed to adapt to industrial production is suitable, avoiding performance fluctuations caused by minute deviations in fixed proportions, reducing the difficulty of production control, and adapting to large-scale mass production. Detailed Implementation

[0029] The technical solution of the present invention will be further described below through embodiments.

[0030] Example 1 A glass powder for the front grid paste of a TOPCon high sheet resistance solar cell suitable for the LECO process, the raw materials are weighed according to the following molar amounts (total moles 100mol): PbO 11.65mol, B2O3 51.31mol, GeO2 2.73mol, Al(OH)3 6.82mol, BaO 5.62mol, Nd2O3 0.58mol, BeO 21.29mol. After converting the molar mass of each component to mass, weigh them accurately.

[0031] The preparation method is as follows: Al(OH)3 was dried at 120℃ for 2 hours, and BeO was pulverized to a particle size ≤1μm; All raw materials were fed into a planetary ball mill, using zirconia balls as the grinding medium at a ball-to-material ratio of 8:1 and a rotation speed of 300 r / min for 2 hours of wet milling. The mixture was then spray-dried and granulated (inlet temperature 200℃, outlet temperature 80℃) to obtain particles with a diameter of 50-100 μm. The particles were then placed in a platinum crucible, melted and held at 1220℃ in a muffle furnace for 2 hours, and water-quenched to obtain glass fragments. After dry milling for 4 hours, the fragments were passed through a 1000-mesh sieve to obtain glass powder with a particle size ≤15 μm.

[0032] The glass powder was mixed with silver powder (average particle size 1.0 μm) and organic carrier (terpineol: ethyl cellulose mass ratio 95:5) at a mass ratio of 2.5:82:15.5. The mixture was stirred for 30 min at 200 rpm in a high-speed mixer, milled three times with a three-roll mill, and ultrasonically dispersed for 15 min to prepare the front fine grid slurry for TOPCon high sheet resistance solar cells. After screen printing with 200 mesh and drying at 150℃ for 10 min, the cells were processed using LECO laser technology (laser intensity 120W, scanning speed 80mm / s, spot diameter 0.8mm) and assembled into TOPCon high sheet resistance cells (sheet resistance 120Ω / □). Performance tests were then conducted, and the test results are shown in Table 1 below.

[0033] Example 2 A glass powder for the front grid paste of a TOPCon high sheet resistance solar cell suitable for the LECO process, the raw materials are weighed according to the following molar amounts (total moles 100mol): The raw materials are accurately weighed as follows: PbO 13.65mol, B2O3 54.31mol, GeO2 3.34mol, Al(OH)3 4.50mol, BaO 5.62mol, Nd2O3 0.58mol, and BeO 18.00mol.

[0034] The preparation process was the same as in Example 1, with only minor adjustments to the melting process: melting and holding at 1210℃ in a muffle furnace for 2 hours; the pulping, printing, and LECO process parameters were the same as in Example 1, and TOPCon high sheet resistance cells (sheet resistance 120Ω / □) were assembled. The test results are shown in Table 1 below.

[0035] Example 3 A glass powder for the front grid paste of a TOPCon high sheet resistance solar cell suitable for the LECO process, the raw materials are weighed according to the following molar amounts (total moles 100mol): The raw materials are accurately weighed as follows: PbO 10.65mol, B2O3 50.31mol, GeO2 1.93mol, Al(OH)3 8.50mol, BaO 4.55mol, Nd2O3 0.58mol, and BeO 23.48mol.

[0036] The preparation process was the same as in Example 1, except for a slight adjustment to the melting process: melting and holding at 1230℃ in a muffle furnace for 2 hours; the pulping, printing, and LECO process parameters were the same as in Example 1, and the TOPCon high sheet resistance battery (sheet resistance 120Ω / □) was assembled. The test results are shown in Table 1 below.

[0037] Example 4 A glass powder for the front grid paste of a TOPCon high sheet resistance solar cell suitable for the LECO process, the raw materials are weighed according to the following molar amounts (total moles 100mol): The raw materials are accurately weighed as follows: PbO 9.5mol, B2O3 55.31mol, GeO2 2.30mol, Al(OH)3 6.82mol, BaO 4.2mol, Nd2O3 0.58mol, and BeO 21.29mol.

[0038] The preparation process was the same as in Example 1, except for a slight adjustment to the melting process: melting and holding at 1215℃ in a muffle furnace for 2 hours; the pulping, printing and LECO process parameters were the same as in Example 1, and the TOPCon high sheet resistance battery (sheet resistance 120Ω / □) was assembled. The test results are shown in Table 1 below.

[0039] Example 5 A glass powder for the front grid paste of a TOPCon high sheet resistance solar cell suitable for the LECO process, the raw materials are weighed according to the following molar amounts (total moles 100mol): The raw materials are accurately weighed as follows: PbO 14.5mol, B2O3 50.31mol, GeO2 1.83mol, Al(OH)3 5.69mol, BaO 7.80mol, Nd2O3 0.58mol, and BeO 19.29mol.

[0040] The preparation process was the same as in Example 1, with only minor adjustments to the melting process: melting and holding at 1225℃ in a muffle furnace for 2 hours; the pulping, printing, and LECO process parameters were the same as in Example 1, and the TOPCon high sheet resistance battery (sheet resistance 120Ω / □) was assembled. The test results are shown in Table 1 below.

[0041] Example 6 A glass powder for the front grid paste of a TOPCon high sheet resistance solar cell suitable for the LECO process, the raw materials are weighed according to the following molar amounts (total moles 100mol): The raw materials are accurately weighed as follows: PbO 13.65mol, B2O3 51.12mol, GeO2 1.20mol, Al(OH)3 6.82mol, BaO 5.62mol, Nd2O3 0.30mol, and BeO 21.29mol.

[0042] The preparation process was the same as in Example 1, with only minor adjustments to the melting process: melting and holding at 1218℃ in a muffle furnace for 2 hours; the pulping, printing, and LECO process parameters were the same as in Example 1, and TOPCon high sheet resistance cells (sheet resistance 120Ω / □) were assembled. The test results are shown in Table 1 below.

[0043] Example 7 A glass powder for the front grid paste of a TOPCon high sheet resistance solar cell suitable for the LECO process, the raw materials are weighed according to the following molar amounts (total moles 100mol): Molecular percentages: PbO 11.15mol, B2O3 51.50mol, GeO2 4.20mol, Al(OH)3 6.82mol, BaO 4.96mol, Nd2O3 0.90mol, BeO 20.47mol. The raw materials are weighed accurately.

[0044] The preparation process was the same as in Example 1, except for a slight adjustment to the melting process: melting and holding at 1222℃ in a muffle furnace for 2 hours; the pulping, printing, and LECO process parameters were the same as in Example 1, and the TOPCon high sheet resistance battery (sheet resistance 120Ω / □) was assembled. The test results are shown in Table 1 below.

[0045] Comparative Example 1 Except for the absence of Al(OH)3 and BeO, the remaining components were kept in their optimal molar percentages (PbO 11.65 mol, B2O3 79.42 mol, GeO2 2.73 mol, BaO 5.62 mol, Nd2O3 0.58 mol, with the missing portion filled by B2O3 to reach 100 mol). Following the same preparation method, pulping process (organic carrier terpineol:ethyl cellulose mass ratio 95:5) and LECO process parameters as in Example 1, a TOPCon battery with a sheet resistance of 120 Ω / □ was assembled. The test results are shown in Table 1 below. Compared to Example 1 of this invention, the contact resistance increased by 30.0%, the open-circuit voltage decreased by 1.8%, and the battery efficiency decreased by 3.2%, indicating that the synergistic effect of Al(OH)3 and BeO is crucial for improving battery performance.

[0046] Comparative Example 2 Except for the absence of Al(OH)3, the remaining components were kept in their optimal molar percentages (PbO 11.65mol, B2O3 58.13mol, GeO2 2.73mol, BaO 5.62mol, Nd2O3 0.58mol, BeO 21.29mol, with the missing portion filled by B2O3 to reach 100mol). Following the same preparation method, slurry preparation process, and LECO process parameters as in Example 1, a 120Ω / □ TOPCon battery was assembled, and the test results are shown in Table 1 below. Compared to Example 1 of this invention, the contact resistance increased by 37.3%, and the battery efficiency decreased by 2.7%; demonstrating that Al(OH)3 is the core component for reducing contact resistance and is indispensable.

[0047] Comparative Example 3 Except for the absence of BeO, the remaining components were kept in their optimal molar percentages (PbO 11.65mol, B2O3 72.60mol, GeO2 2.73mol, Al(OH)3 6.82mol, BaO 5.62mol, Nd2O3 0.58mol, with the missing portion filled by B2O3 to reach 100mol). Following the same preparation method, slurry preparation process, and LECO process parameters as in Example 1, a 120Ω / □ TOPCon battery was assembled, and the test results are shown in Table 1 below. Compared to Example 1 of this invention, the open-circuit voltage decreased by 2.2%, and the battery efficiency decreased by 2.5%; demonstrating that BeO is a key component for improving the open-circuit voltage and is crucial for passivation protection.

[0048] Comparative Example 4 Al(OH)3 was replaced with an equimolar amount of Al2O3, while the remaining components remained unchanged at their optimal molar percentages (PbO 11.65 mol, B2O3 51.31 mol, GeO2 2.73 mol, Al2O3 6.82 mol, BaO 5.62 mol, Nd2O3 0.58 mol, BeO2 1.29 mol). Following the same preparation method, slurry preparation process, and LECO process parameters as in Example 1, a 120 Ω / □ TOPCon battery was assembled. The test results are shown in Table 1 below. Compared to Example 1 of this invention, the contact resistance increased by 25.3%, demonstrating that Al(OH)3 exhibits higher reactivity and a more significant improvement in contact performance under the LECO process compared to traditional Al2O3.

[0049] Comparative Example 5 Except for the absence of Nd₂O₃, the remaining components were kept in their optimal molar percentages (PbO 11.65 mol, B₂O₃ 51.89 mol, GeO₂ 2.73 mol, Al(OH)₃ 6.82 mol, BaO 5.62 mol, BeO 21.29 mol, with the missing portion filled by B₂O₃ to 100 mol). Following the same preparation method, slurry preparation process, and LECO process parameters as in Example 1, a 120 Ω / □ TOPCon battery was assembled, and the test results are shown in Table 1 below. Compared to Example 1 of this invention, the battery efficiency decreased by 1.2%; indicating that trace doping with Nd₂O₃ can optimize optical performance and improve interface stability, while its absence slightly reduces performance.

[0050] Comparative Example 6 Except for the absence of GeO2, the remaining components were kept in their optimal molar percentages (PbO 11.65 mol, B2O3 54.04 mol, Al(OH)3 6.82 mol, BaO 5.62 mol, Nd2O3 0.58 mol, BeO 21.29 mol, with the missing portion filled by B2O3 to reach 100 mol). Following the same preparation method, slurry preparation process, and LECO process parameters as in Example 1, a 120 Ω / □ TOPCon battery was assembled, and the test results are shown in Table 1 below. Compared to Example 1 of this invention, the battery efficiency decreased by 1.5%; this indicates that GeO2 can improve the chemical stability of the glass powder and inhibit crystallization, and its absence leads to decreased contact interface stability and deteriorated performance.

[0051] Table 1

[0052] The above seven examples and six comparative examples fully demonstrate that the present invention, through precise proportioning of each component, especially the synergistic effect of Al(OH)3 and BeO, and the optimization effect of Nd2O3 and GeO2, can significantly optimize the contact performance and open-circuit voltage of the front fine grid of TOPCon high sheet resistance battery, adapt to LECO laser process, and greatly improve battery efficiency. The synergistic effect of each component is indispensable, and it has significant technical advantages and industrial application value.

[0053] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. A glass powder for the front-side fine grid paste of TOPCon high sheet resistance solar cells suitable for LECO process, characterized in that, The raw material composition, by molar percentage, is as follows: PbO 9.5~14.5 mol%, B2O3 49.0~59.0 mol%, GeO2 1.2~4.2 mol%, Al(OH)3 4.5~8.5 mol%, BaO 4.2~7.8 mol%, Nd2O3 0.3~0.9 mol%, BeO 18.0~25.0 mol%.

2. The glass powder according to claim 1, characterized in that, The particle size of the glass powder is ≤15μm.

3. The glass powder according to claim 1, characterized in that, The raw material composition, by molar percentage, is: PbO 11.65 mol%, B2O3 51.31 mol%, GeO2 2.73 mol%, Al(OH)3 6.82 mol%, BaO 5.62 mol%, Nd2O3 0.58 mol%, BeO 21.29 mol%.

4. The glass powder according to claim 1, characterized in that, The purity of Al(OH)3 is ≥99.99%, and it is dried at 120℃ for 2 hours before use; the purity of BeO is ≥99.99%, and the particle size is ≤1μm.

5. A method for preparing the glass powder according to any one of claims 1-4, characterized in that, Includes the following steps: (1) Raw material pretreatment: Weigh each component by molar percentage, dry Al(OH)3 to remove water, and pulverize BeO to a particle size ≤1μm; (2) Mixing and grinding: The pretreated raw materials are wet-ground for 2 hours to obtain a uniformly mixed slurry; (3) Drying and granulation: The mixed slurry is spray-dried to obtain particles with a particle size of 50~100μm; (4) Melt quenching: Melt the particles at 1200-1250℃ and hold for 2 hours, then quench with water to obtain glass fragments; (5) Ultrafine grinding: Dry grind the glass fragments for 4 hours and pass them through a 1000-mesh sieve to obtain the finished glass powder.

6. The preparation method according to claim 5, characterized in that, In step (2), wet grinding is carried out in a planetary ball mill. The grinding media is 2mm zirconia balls, the grinding liquid is pure water, the ball-to-water ratio is 8:1:0.5, and the rotation speed is 300r / min.

7. The preparation method according to claim 5, characterized in that, In step (3), the spray drying inlet temperature is 200℃ and the outlet temperature is 80℃.

8. The preparation method according to claim 5, characterized in that, In step (5), dry grinding is carried out in a planetary ball mill, using 10mm zirconia balls as the grinding media, with a ball-to-material ratio of 2:1 and a rotation speed of 200r / min.

9. A TOPCon high sheet resistance cell front grid paste suitable for LECO process, characterized in that, It contains the glass powder as described in any one of claims 1-4.

10. The TOPCon high sheet resistance cell front grid paste suitable for LECO process according to claim 9, characterized in that, The raw material composition, by mass parts, is: 2-3 parts of glass powder as described in any one of claims 1-4, 80-85 parts of silver powder, and 12-18 parts of organic carrier.

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