阅读说明：本技术 一种玻璃粉及含该玻璃粉的银浆 (Glass powder and silver paste containing same ) 是由 毛平 赵新 郑金华 于 2020-08-26 设计创作，主要内容包括：本发明公开的一种玻璃粉及其制备方法和含该玻璃粉的银浆,玻璃粉为含有钒-碲-银的玻璃粉,该玻璃粉的软化温度为230-330℃,玻璃粉的中值粒径为1-2μm,将该玻璃粉应用于银浆中,可以满足银浆在230-400℃的温度烧结的同时保证银浆烧结后,该玻璃体系形成牢固的三维网络结构,提升银电极的焊接拉力,在该玻璃粉的中还添加了其他金属元素使得玻璃粉的网络结构更加致密且完整,同时保证玻璃粉的稳定性。含有该玻璃粉的银浆中选择一种径大小均匀,粒径分布范围窄,分散性好且具有优异的导电性能的纳米银浆,制备的银浆可以在230-400℃温度下进行烧结,且可以在不过度损伤电池片的前提下大大提高太阳能电池的光电转换效率。(The glass powder is glass powder containing vanadium, tellurium and silver, the softening temperature of the glass powder is 230-plus-one temperature, the median particle size of the glass powder is 1-2 mu m, the glass powder is applied to the silver paste, the requirement that the silver paste is sintered at the temperature of 230-plus-one temperature of 400 ℃ can be met, the glass system can form a firm three-dimensional network structure after the silver paste is sintered, the welding tension of a silver electrode is improved, other metal elements are added into the glass powder, the network structure of the glass powder is more compact and complete, and the stability of the glass powder is ensured. The nano silver paste with uniform diameter, narrow particle size distribution range, good dispersibility and excellent conductivity is selected from the silver paste containing the glass powder, the prepared silver paste can be sintered at the temperature of 230-400 ℃, and the photoelectric conversion efficiency of the solar cell can be greatly improved on the premise of not excessively damaging the cell.)

1. A glass frit is characterized in that: the glass powder is a vanadium-tellurium-silver glass powder containing a formula (I):

V_a-Te_b-Ag_d-M_c-N_e(Ⅰ)，

wherein a, b, c or d is more than 0 and less than 1, the sum of a, b, c and d is 1, wherein a is more than or equal to 0.1 and less than or equal to 0.3, b is more than or equal to 0.3 and less than or equal to 0.5, c is more than or equal to 0.01 and less than or equal to 0.03, d is more than or equal to 0.3 and less than or equal to 0.5, M is one or more elements, and e is a natural number for balancing the charge of the glass powder.

2. A glass frit as claimed in claim 1, wherein: the M element is at least one of boron element, aluminum element, gallium element, silicon element, germanium element, tin element, phosphorus element, niobium element, titanium element, molybdenum element, tungsten element, chromium element, alkali metal element and alkaline earth metal element.

3. A glass frit as claimed in claim 1, wherein: the N element is at least one selected from oxygen element, halogen element, carbonate and nitrate.

4. A glass frit as claimed in claim 1, wherein: the softening temperature of the glass powder is 230-330 ℃, and the median particle size of the glass powder is 1-2 μm.

5. A silver paste containing the glass frit according to any one of claims 1 to 4, wherein: the silver paste containing the glass powder is prepared by mixing 80-95 parts by mass of silver powder, 5-13 parts by mass of organic carrier and 2-4 parts by mass of glass powder.

6. The silver paste containing the glass powder, according to claim 5, is characterized in that: the median particle diameter D of the silver powder₅₀Is 50-500 nm.

7. The silver paste containing the glass powder, according to claim 5, is characterized in that: the specific surface area of the silver powder is 3-10m²The burning loss rate of the silver powder after being ablated for 30min at 540 ℃ is 0.2-0.4%, and the tap density of the silver powder is 6-8 g/mL.

8. The silver paste containing the glass powder, according to claim 5, is characterized in that: the organic carrier is at least one of thixotropic agent, thickening agent, toughening agent, binder, surfactant, antioxidant, dispersant and solvent.

9. The silver paste containing the glass powder according to any one of claims 6 to 8, wherein the silver paste comprises: the silver paste containing the glass powder is used as a front main grid, the welding tension is 2-4.3N, the sintering temperature of the silver paste containing the glass powder is 230-400 ℃, and the silver paste containing the glass powder is used for preparing a front electrode of a tunneling oxide layer passivation contact solar cell.

10. The method for producing glass frit according to any of claims 1 to 4, wherein: the method comprises the following steps:

step 1: weighing the components in the glass powder according to a ratio, and uniformly mixing to obtain a mixed material;

step 2: putting the mixed material in the step 1 into a ball mill for grinding for 4-6h to uniformly mix, then putting the ground mixed material into a dried corundum crucible, and putting the corundum crucible into a resistance furnace with the temperature of 1000-;

and step 3: taking the corundum crucible in the step 2 out of the resistance furnace, then quickly pouring the molten mixed material into cold water for water quenching, and finally drying the water-quenched mixed material to obtain a solid mixture material;

and 4, step 4: and (3) putting the solid mixed material in the step (3) into an airflow mill for grinding, wherein the working air pressure of the airflow mill is 0.3-0.5MPa, and the rotating speed of a grading wheel is 400-600r/min, and after grinding, putting the solid mixed material into a drying box for drying to obtain the glass powder.

Technical Field

The invention relates to the technical field of conductive materials containing metal or alloy, in particular to glass powder and silver paste containing the glass powder.

Background

A tunnel oxide passivation contact (TOPCon) solar cell is a novel silicon solar cell proposed by franhoff solar research, germany. The tunneling oxide layer passivation contact solar cell adopts an n-type silicon wafer, and the solar cell sequentially comprises the following structures from top to bottom: front electrode, front SiN_xLayer of Al₂O₃Layer, P⁺Doping layer, n-type silicon wafer and SiO₂Tunneling oxide layer, N⁺Polysilicon layer, backside SiN_xA layer and a back electrode.

Patent No. cn201910354176.x, applied to 29/4/2019 by the same company, discloses a metallization method for a front electrode of an N-type solar cell, and the metallization method comprises the following steps: in SiN_xPrinting aluminum paste on the layer to form a first fine grid, then overprinting silver paste on the first fine grid to form a second fine grid, and finally printing front silver paste on the first fine grid to form a main grid. The aluminum paste used as the first fine grid has larger resistance, the front electrode has the function of increasing the line resistance of the fine grid and the front silicon chip, and the requirements of the front electrode structure on the silver paste of the second fine grid overprinted on the first fine grid are as follows: the thin gate aluminum paste has low line resistance, good silver-aluminum adhesion with the first thin gate aluminum paste, low silver-aluminum contact resistance, and thin gate lines as much as possible, and can be sintered at a lower temperature to reduce damage to silicon wafers. The requirements of the front main grid silver paste printed on the first fine grid are as follows: the front main grid slurry has high activity, good welding tension, low wire resistance, low sintering temperature, low composition and the like.

Disclosure of Invention

In order to solve the problems, the invention provides glass powder, a preparation method thereof and a silver paste containing the glass powder, wherein the glass powder is used as a core material of low-temperature sintered silver paste, the softening point of the glass powder is 230-330 ℃, so that the silver paste containing the glass powder has higher activity in a lower-temperature environment, the silver paste can be printed on a first fine grid to serve as second fine grid paste and also serve as main grid paste, and the requirements of low-temperature sintering are met, the wire resistance is low, the compounding is small, the welding tension is good, and the like, and the specific contents of the invention are as follows:

the invention provides glass powder, which is technically characterized in that: the glass powder is a vanadium-tellurium-silver glass powder containing a formula (I):

V_a-Te_b-Ag_d-M_c-N_e， (1)，

wherein a, b, c or d is more than 0 and less than 1, the sum of a, b, c and d is 1, wherein a is more than or equal to 0.1 and less than or equal to 0.3, b is more than or equal to 0.3 and less than or equal to 0.5, c is more than or equal to 0.01 and less than or equal to 0.03, d is more than or equal to 0.3 and less than or equal to 0.5, M is one or more elements, and e is a natural number for balancing the charge of the glass powder.

In some embodiments of the present invention, the M element is at least one selected from the group consisting of boron, aluminum, gallium, silicon, germanium, tin, phosphorus, niobium, titanium, molybdenum, tungsten, chromium, alkali metal, and alkaline earth metal.

In some embodiments of the present invention, the N element is at least one selected from the group consisting of oxygen, halogen, carbonate, and nitrate.

In some embodiments of the present invention, the softening temperature of the glass frit is 230-330 ℃, and the median particle size of the glass frit is 1-2 μm.

The invention also provides a silver paste containing the glass powder, which has the technical points that: the silver paste containing the glass powder is prepared by mixing 80-95 parts by mass of silver powder, 5-13 parts by mass of organic carrier and 2-4 parts by mass of glass powder.

In some embodiments of the invention, the silver powder has a median particle diameter D₅₀Is 50-500 nm.

In some embodiments of the present invention, the silver powder has a specific surface area of 3 to 10m²The burning loss rate of the silver powder after being ablated for 30min at 540 ℃ is 0.2-0.4%, and the tap density of the silver powder is 6-8 g/mL.

In some embodiments of the present invention, the organic vehicle is at least one of a thixotropic agent, a thickener, a toughener, a surfactant, an antioxidant, a binder, a dispersant, and a solvent.

The solvent is selected from solvents with lower saturated vapor pressure at the same temperature, and the solvent can be at least one of diethylene glycol dibutyl ether, alcohol ester dodecaacetate and ethylene glycol diacetate.

In some embodiments of the invention, the silver paste containing the glass powder is used as a front main grid, the welding tension of the front main grid is 2-4.3N, the sintering temperature of the silver paste containing the glass powder is 230-400 ℃, and the silver paste containing the glass powder is used for preparing a front electrode of a tunneling oxide layer passivation contact solar cell.

The invention also provides a preparation method of the glass powder, which is technically characterized by comprising the following steps: the method comprises the following steps:

step 1: weighing the components in the glass powder according to a ratio, and uniformly mixing to obtain a mixed material;

step 2: putting the mixed material in the step 1 into a ball mill for grinding for 4-6h to uniformly mix, then putting the ground mixed material into a dried corundum crucible, and putting the corundum crucible into a resistance furnace with the temperature of 1000-;

and step 3: taking the corundum crucible in the step 2 out of the resistance furnace, then quickly pouring the molten mixed material into cold water for water quenching, and finally drying the water-quenched mixed material to obtain a solid mixture material;

and 4, step 4: and (3) putting the solid mixed material in the step (3) into an airflow mill for grinding, wherein the working air pressure of the airflow mill is 0.3-0.5MPa, and the rotating speed of a grading wheel is 400-600r/min, and after grinding, putting the solid mixed material into a drying box for drying to obtain the glass powder.

Compared with the prior art, the invention has the beneficial effects that:

1. the glass powder is vanadium-tellurium-silver glass powder, the strength of a network structure of the glass powder is strong, the softening temperature of the glass powder is 230-plus-one temperature (330 ℃), when the glass powder is applied to silver paste, the requirement that the silver paste is sintered at the temperature of 230-plus-one temperature (400 ℃) can be met, a firm three-dimensional network structure can be formed in a glass system after the silver paste is sintered, the welding tension of a front silver electrode can be improved when the glass powder is applied to main grid paste, and the contact resistance of silver and aluminum and the line resistance of the silver electrode can be reduced when the glass powder is applied to overprinted fine grid paste.

2. The glass powder is also supplemented with metal elements such as boron, aluminum, gallium, silicon, germanium, tin, phosphorus, niobium, titanium, molybdenum, tungsten, chromium, alkali metal, alkaline earth metal and the like, and the addition of the metal elements can enable the network structure of the glass powder to be more compact and complete and ensure the stability of the glass powder.

3. According to the silver paste containing the glass powder, the selected nano silver powder is uniform in particle size, narrow in particle size distribution range, good in dispersity and excellent in conductivity, and the median particle diameter D of the nano silver powder is₅₀50-500nm, and specific surface area of 3-10m²The burning loss rate of the silver powder after being ablated for 30min at 540 ℃ is 0.2-0.4%, the tap density of the silver powder is 6-8g/mL, and the nano silver powder is applied to preparing low-temperature sintered silver paste, so that the silver paste has better fluidity and less damage to a silicon wafer when being sintered at the temperature of 230-400 ℃, and the welding tension is 2-4.3N when the silver paste is used as a front main grid.

Drawings

FIG. 1 is a DSC of glass frits prepared by examples 1, 4 of the present invention;

FIG. 2 is a DSC of glass frit produced in example 2 of the present invention;

FIG. 3 is a DSC of glass frits prepared by examples 3 and 5 of the present invention;

FIG. 4 is an SEM scanning electron micrograph of a silver paste prepared in example 1 of the present invention;

FIG. 5 is an SEM scanning electron micrograph of a silver paste prepared in example 2 of the present invention;

FIG. 6 is an SEM scanning electron micrograph of a silver paste prepared in example 3 of the present invention;

FIG. 7 is an SEM scanning electron micrograph of a silver paste prepared in example 4 of the present invention;

FIG. 8 is an SEM scanning electron micrograph of a silver paste prepared in example 5 of the present invention;

FIG. 9 is an SEM image of silver powder selected in example 1 of the present invention;

FIG. 10 is an SEM image of silver powder selected in example 2 of the present invention;

FIG. 11 is an SEM image of selected silver powder in example 3 of the present invention;

FIG. 12 is an SEM image of selected silver powder in example 4 of the present invention;

FIG. 13 is an SEM image of silver powder selected in example 5 of the present invention.

Detailed Description

In order to solve the problems, the invention provides glass powder, a preparation method thereof and silver paste containing the glass powder, wherein the glass powder has a low softening point, the silver paste containing the glass powder has high activity in a low-temperature environment, and the tensile force of a front electrode formed by printing is high, and the glass powder comprises the following specific contents:

the invention provides glass powder with a softening temperature of 230-330 ℃, wherein 2-4 parts by mass of the glass powder are matched with 80-95 parts by mass of specific nano silver powder and 5-13 parts by mass of organic carrier with lower low saturated vapor pressure to prepare low-temperature sintered silver paste, the low-temperature sintered silver paste can be used for forming a front fine grid or a front main grid on the front surface of a tunneling oxide layer in passivation contact with solar energy through screen printing, when the front fine grid is used as the front fine grid, the front fine grid is overprinted on aluminum paste, the width of the front fine grid is only 25-40 mu m, the fine grid line is low in resistance, silver and aluminum are well attached, the interaction between silver and aluminum is small, and the silver and aluminum contact resistance is low. When the silver paste is used as a main grid, the silver paste is high in activity, has better welding tension of 2-4.3N, can be sintered at the temperature of 230-400 ℃, and has less damage to a silicon wafer. The literature reports that the highest temperature which can be borne by a P-N junction of a heterojunction solar cell is 230 ℃, and the low-temperature sintered silver paste can be used in the heterojunction solar cell and has good photoelectric conversion efficiency on the premise of not damaging the P-N junction of the heterojunction solar cell.

Glass powder

The glass powder of the present invention is a glass powder comprising vanadium-tellurium-silver of formula (i):

V_a-Te_b-Ag_d-M_c-N_e(Ⅰ)，

the vanadium-tellurium-silver glass powder has a strong network structure strength of a glass system, and can enable the silver paste to have better welding tension when being applied to the silver paste. The M element is at least one of boron element, aluminum element, gallium element, silicon element, germanium element, tin element, phosphorus element, niobium element, titanium element, molybdenum element, tungsten element, chromium element, alkali metal element and alkaline earth metal element, and the addition of the metal elements can enable the network structure of the glass powder to be more compact and complete and ensure the stability of the glass powder. Wherein the N element is at least one selected from the group consisting of oxygen element, halogen element, carbonate and nitrate. The softening temperature of the glass powder of the system is 230-330 ℃, the median particle size of the glass powder of the system can be 1-2 μm, when the median particle size of the glass powder is smaller than 1 μm, the solar cell silicon wafer is easily damaged in the sintering process due to overhigh activity of the glass powder, and when the median particle size of the glass powder is larger than 2 μm, the specific surface area of the glass powder is relatively smaller due to large particle size, so that the softening temperature of the glass powder is increased, the glass powder is made into silver paste, and the sintering temperature of the silver paste is overhigh.

Silver powder

Median particle diameter D of silver powder used in the present invention₅₀The silver powder has the particle size of 50-500nm, and the silver powder has the advantages of uniform particle size, narrow particle size distribution range, good dispersibility and excellent conductivity. The silver powder of the present invention has a specific surface area of 3 to 10m²The fact shows that the sintering temperature of the silver paste prepared by the silver powder is lower along with the increase of the specific surface area of the silver powder, so that the increase of the specific surface area of the silver powder is more directly effective to reduce the sintering temperature of the silver paste, but the increase of the specific surface area of the silver powder is along with the increase of the specific surface area of the silver powderThe silver powder is easy to agglomerate, and the silver paste prepared from the silver powder with larger specific surface area is easy to have oxidation reaction with oxygen in the air in the sintering process due to higher oxidation activity of the silver powder, so that the quality of the silver powder is influenced, and when the specific surface area of the silver powder is increased to 10m²Above/g, the silver powder can undergo severe agglomeration and oxidation reactions. The burning loss rate of the silver powder ablated at 540 ℃ for 30min is 0.2-0.4%, theoretically, the smaller the burning loss rate of the silver powder is, the higher the sintering activity of the silver powder is, and the sintering temperature of the silver powder can be reduced when the silver powder is used as conductive metal powder of the silver paste. The tap density of the silver powder is 6-8g/mL, and the applicant finds through experiments that the higher the tap density of the silver powder is, the higher the welding tension of the silver powder prepared from the silver powder as a front main grid is, and the tap density of the silver powder is most suitably determined to be 6-8g/mL in combination with the characteristics of the invention.

Organic vehicle

The organic carrier is at least one of thixotropic agent, thickening agent, toughening agent, surfactant, antioxidant, binder, dispersant and solvent. The silver paste prepared by adding the thixotropic agent, the thickening agent, the toughening agent, the surfactant and the antioxidant has better plastic property and rheological property, wherein the solvent is selected from solvents with lower saturated vapor pressure at the same temperature, the solvents can be at least one of diethylene glycol dibutyl ether, alcohol ester dodeca and ethylene glycol diacetate, the solvents are solvents with lower saturated vapor pressure, the solvents have better thermal decomposition capability, if the saturated vapor pressure of the solvents is too high, organic solvents in the prepared silver paste can not be completely volatilized and remain in the silver paste in the low-temperature sintering process, so that the line resistance of the silver paste is increased, and the photoelectric conversion efficiency of the silver paste is further influenced.

The silver paste containing the glass powder is used as a front main grid, the welding tension of the front main grid is 2-4.3N, the sintering temperature of the silver paste containing the glass powder is 230-400 ℃, and the silver paste containing the glass powder is used for preparing a front electrode of a tunneling oxide layer passivation contact solar cell.

The technical solutions in the embodiments of the present invention will be clearly and completely described below so that those skilled in the art can better understand the advantages and features of the present invention, and thus the scope of the present invention will be more clearly defined. The embodiments described herein are only a few embodiments of the present invention, rather than all embodiments, and all other embodiments that can be derived by one of ordinary skill in the art without inventive faculty based on the embodiments described herein are intended to fall within the scope of the present invention. Unless otherwise specified, the starting materials in the present invention are all commercially available.