CN111511697A

CN111511697A - Glass powder, glass powder composition and preparation method of glass powder

Info

Publication number: CN111511697A
Application number: CN201880047101.0A
Authority: CN
Inventors: 朱鹏
Original assignee: Nantong T-Sun New Energy Co ltd
Current assignee: Nantong T-Sun New Energy Co ltd; Nantong T Sun New Energy Co Ltd
Priority date: 2018-08-03
Filing date: 2018-08-03
Publication date: 2020-08-07
Also published as: DE112018007808T5; WO2020024254A1

Abstract

The glass powder is used for preparing crystalline silicon solar cell slurry and comprises the following components in parts by mass: 30-90 parts of PbO and 5-25 parts of B₂O₃2-10 parts of SiO₂5 to 20 parts of ZnO and 0.1 to 13 parts of MxOy, wherein M is a first main group element or a second main group element, and the softening temperature of the glass powder is 280 to 400 ℃. The glass powder composition also comprises auxiliary glass powder which comprises Bi₂O₃、B₂O₃And ZnO. Drying the raw materials; smelting according to a set program, wherein the set program comprises a temperature rise stage and a heat preservation stage, and the temperature of the heat preservation stage is set as950-1050 ℃, and the duration of the heat preservation stage is set to be 1-2 hours; then cooling, crushing and screening to obtain the glass powder.

Description

Glass powder, glass powder composition and preparation method of glass powder

Technical Field

The invention relates to the field of solar cells and conductive paste, in particular to glass powder, a glass powder composition and a preparation method of the glass powder.

Background

In order to deal with the dilemma of conventional energy exhaustion required in the future, the new energy industry has received more and more attention and attention in many countries and regions in recent years. The solar cell industry is rapidly developed under the background, and the crystalline silicon solar cell is still the most important product and technology research and development direction in the industry at present. In recent years, attention has been paid to passivation of a dielectric film used for the back surface of a Cell, and a thin film deposition manufacturing technique and equipment have become more mature, and with the introduction of a laser technique, the yield of a back surface passivation type solar Cell (hereinafter, referred to as "PERC Cell") has been increasing year by year. PERC cell via passivation film (SiN)_x、SiO₂、Al₂O₃Etc.) to reduce energy loss caused by recombination occurring at the back electrode of the battery, thereby improving conversion efficiency. The double-sided PERC battery is a new focus of attention in the industry at the present stage, but the process requirement is high, and the laser process is adopted to open holes/grooves in the passivation film on the back side and then metalize the passivation film to realize ohmic contact.

It is also disclosed in the art that the same effect as laser grooving can be achieved by printing a "corrosive slurry" directly on the surface of the passivation layer and burning through the passivation layer during high temperature sintering to form the contact. However, the back electrode paste needs to be formed by secondary printing, which increases the cost. In order to reduce the process requirement and the production cost, the industry also proposes to use the co-sintering slurry to form a back electrode and burn through a passivation layer to form good ohmic contact at the same time of forming the back electrode by one-time printing. The co-sintering slurry needs to react with a corresponding passivation film in a sintering stage, needs to control back surface recombination, and needs higher process stability.

Generally, the slurry is prepared by uniformly stirring and mixing metal powder, glass powder and an organic phase according to a predetermined ratio. The composition system and the reaction generation process of the glass powder are very complicated, and the influence on the performance of the slurry is very large. Therefore, it is necessary to optimize and develop the existing glass powder to realize the development of the above-mentioned "co-sintering paste" and meet the production requirements of the PERC battery.

Disclosure of Invention

The invention aims to provide glass powder, a glass powder composition and a preparation method of the glass powder, which are suitable for preparing slurry required by the metallization of the back of a PERC battery, can fully and uniformly react with a passivation layer on the back of the PERC battery, and simplify the production process of the PERC battery.

In order to realize the aim, the invention provides glass powder for preparing crystalline silicon solar cell slurry, which comprises the following components in parts by mass: 30-90 parts of PbO and 5-25 parts of B₂O₃2-10 parts of SiO₂5 to 20 parts of ZnO and 0.1 to 13 parts of M_xO_yWherein M is a first main group element or a second main group element, and the softening temperature of the glass powder is 280-400 ℃.

As a further improvement of the invention, the median particle size of the glass powder is 0.5-5 μm.

As a further improvement of the invention, said M_xO_yIs Na₂O、CaO、K₂O and L i₂At least one of O.

As a further improvement of the invention, the glass powder also comprises Al₂O₃CuO and P₂O₅At least one of (1).

The invention also provides a glass powder composition, which comprises the glass powder and auxiliary glass powder, wherein the auxiliary glass powder comprises Bi₂O₃、B₂O₃And ZnO, wherein the softening temperature of the auxiliary glass powder is 380-500 ℃; the mass ratio of the main glass powder to the auxiliary glass powder is (1.8-2.2): (0.3-0.5).

As a further improvement of the invention, the auxiliary glass powder has the mass composition of Bi₂O₃：B₂O₃：ZnO＝(3～7)：(1.5～2.5):1。

As a further improvement of the invention, the auxiliary glass powder also comprises SiO₂、Al₂O₃、CuO、TiO₂、Cr₂O₃、NiO、Li₂O and MnO₂One or more of them.

As a further improvement of the invention, the median particle size of the auxiliary glass powder is 0.5-5 μm.

The invention also provides a preparation method of the glass powder, which comprises the following steps:

weighing raw materials, uniformly mixing the raw materials, and drying for 2-5 hours;

transferring the raw materials subjected to drying treatment into a crucible, and then placing the crucible containing the raw materials into a heating chamber to be smelted according to a set program, wherein the set program comprises a temperature rise stage and a heat preservation stage, the temperature of the heat preservation stage is set to be 950-1050 ℃, and the time of the heat preservation stage is set to be 1-2 hours;

cooling the smelted feed liquid by a cold roll to obtain a glass material;

and crushing and screening the glass frit to obtain glass powder.

As a further improvement of the invention, the preparation method further comprises charging protective gas into the heating chamber during the smelting process.

The invention has the beneficial effects that: the glass powder has lower softening temperature and small expansion coefficient, and the prepared slurry is suitable for the back metallization process of the PERC battery. The glass powder can fully and uniformly react with the passivation layer in the high-temperature sintering process, the composite influence on the back surface is small, the electrical property of the battery piece is balanced, and the bending of the battery piece is reduced.

Drawings

FIG. 1 is a schematic view of a scanning electron microscope of the glass powder of the present invention;

FIG. 2 is a partial cross-sectional view of the back surface of a PERC cell made using a slurry of the glass frit of the present invention;

FIG. 3 is a schematic main flow chart of a method for producing a paste using the glass frit of the present invention;

FIG. 4 is a schematic main flow chart of the method for producing the glass frit according to the present invention.

Detailed Description

The present invention will be described in detail below with reference to embodiments shown in the drawings. The present invention is not limited to the embodiment, and structural, methodological, or functional changes made by one of ordinary skill in the art according to the embodiment are included in the scope of the present invention.

The invention provides a paste for a PERC battery, which is particularly suitable for a metallization process of a back surface electrode of a double-sided PERC battery, and the paste printed on the surface of the PERC battery can be mixed with SiN in a high-temperature sintering process_x、SiO₂、Al₂O₃The film layers react and form a better ohmic contact in the corresponding area.

The paste comprises a conductive phase, a glass phase and an organic binder, wherein the conductive phase comprises aluminum powder and aluminum alloy powder, the glass phase comprises glass powder and auxiliary glass powder, and the softening temperature of the auxiliary glass powder is higher than that of the glass powder; the slurry comprises: 65-73 parts by mass of aluminum powder, 3-10 parts by mass of aluminum alloy powder, 1.8-2.2 parts by mass of glass powder, 0.3-0.5 part by mass of auxiliary glass powder and 15-40 parts by mass of organic binder.

The aluminum powder and the aluminum alloy powder are spherical particles, the median particle size of the aluminum powder is 0.1-20 microns, the preferable range of the median particle size of the aluminum powder is 0.1-3 microns, the melting point of the aluminum powder is 450-650 ℃, the preferable range of the melting point of the aluminum powder is 500-600 ℃, and the slurry can be used by matching aluminum powders with different particle sizes. The median particle size of the aluminum alloy powder is 0.5-5 μm, more preferably 2-3 μm, and the melting point of the aluminum alloy powder is 400-600 ℃. The aluminum alloy powder is preferably binary or ternary alloy powder, and specifically, the aluminum alloy powder is one or more of aluminum-boron alloy, aluminum-silicon-boron alloy, aluminum-boron-antimony alloy and aluminum-magnesium alloy. In the high-temperature sintering process, the glass phase is firstly melted, aluminum powder and aluminum alloy powder are soaked, and the molten aluminum powder is shrunk by the surface tension of the glass phase to form a densified film layer when being cooled. The aluminum powder has small particle size, low melting point and high contraction pressure, and the aluminum alloy powder can avoid aluminum thorn protrusions from being formed on the surface of the film layer. In order to further improve the current transmission performance of the slurry after sintering and reduce the series resistance. The guide phase can also be added with partial silver powder, and the median particle size of the silver powder is 0.1-5 μm.

The glass powder comprises the following components in parts by mass: 30-90 parts of PbO and 5-25 parts of B₂O₃2-10 parts of SiO₂5 to 20 parts of ZnO and 0.1 to 13 parts of M_xO_y. Wherein M is a first main group element or a second main group element, and M is_xO_yIn particular Na₂O、CaO、K₂O and L i₂At least one of O. The softening temperature of the glass powder is 280-400 ℃, and preferably, the softening temperature of the glass powder is controlled to be 280-330 ℃. The glass powder has a low melting point, can be melted in advance in the sintering and heating process to fully soak the conductive phase, and is completely settled to facilitate the wetting of the passivation film and the silicon substrate.

The median particle size of the glass powder is 0.5-5 mu m (shown in figure 1), the glass powder is in an amorphous granular shape, powder particles with larger particle sizes are preferably screened out in the actual preparation process, the possibility that the performance of the glass powder is influenced by possible crystal particles is avoided, and the quality of slurry is ensured.

SiO₂And B₂O₃All can form a glass network structure, PbO can be connected with silicon-oxygen tetrahedron to form a special network structure, so that PbO/SiO₂The composition system has a wider glass forming area and enables PbO to have better fluxing property, wherein the PbO has a relatively higher proportion, so that the crystallization can be effectively avoided, and the softening temperature of the glass powder can be reduced. B is₂O₃Low self-melting point, favorable for lowering softening temperature of glass powder, and inhibiting expansion coefficient of glass, B₂O₃And also to provide the glass with proper fluidity after melting. The ZnO component also contributes to lowering of the melting point of the glass frit and can suppress an increase in the expansion coefficient of the glass, and can be used for adjusting the fluidity of the glass after melting. Except that, M_xO_yThe glass network structure can be damaged in the glass smelting process, the viscosity of the glass feed liquid in a molten state is reduced, and the uniform smelting of glass is facilitated.

The glass powder also comprises Al₂O₃、CuO and P₂O₅At least one of (1). Al (Al)₂O₃Can replace partial SiO₂Increasing the chemical stability and acid resistance of the glass powder preparation process, and Al₂O₃Mass composition ratio is less than SiO₂Half of that. P₂O₅The CuO can break the glass network structure, and the chemical stability of the glass powder is not influenced by the addition of a small amount of CuO.

The auxiliary glass powder comprises Bi₂O₃、B₂O₃And ZnO of which the mass composition is Bi₂O₃：B₂O₃: ZnO (3-7): (1.5-2.5) 1. The median particle size of the auxiliary glass powder is 0.5-5 mu m, the softening temperature of the auxiliary glass powder is controlled to be 380-500 ℃, further, the median particle size of the auxiliary glass powder is preferably 2-5 mu m, and the softening temperature is preferably 400-450 ℃. The softening temperature of the auxiliary glass powder is higher than that of the glass powder, so that the auxiliary glass powder and the glass powder are prevented from melting and settling together to form a thick glass layer, and the series resistance is increased.

Bi₂O₃As a better substitute component of PbO, the auxiliary glass powder has the functions of reducing the softening temperature of the glass powder and inhibiting the adjustment of the expansion coefficient of the glass, and can also increase the specific gravity of the auxiliary glass powder, thereby being beneficial to the uniform action of the auxiliary glass powder on a conductive phase in the slurry sintering process. Further, the auxiliary glass powder also comprises SiO₂、Al₂O₃、CuO、TiO₂、Cr₂O₃、NiO、Li₂O and MnO₂One or more of them. The glass powder and the auxiliary glass powder can be mixed according to a set proportion to obtain a corresponding glass powder composition, so that the slurry production and material management and control are facilitated.

The organic binder comprises organic resin, an organic solvent and an organic auxiliary agent, wherein the organic resin is one or more selected from ethyl cellulose, butyl acetate cellulose, phenolic resin, polyaldehyde and cellulose ether, and the mass ratio of the organic resin in the organic binder is 5-30%; the organic solvent is selected from one or more of acetone, terpineol, alcohol ester dodeca, butyl carbitol acetate, glycerol and diethylene glycol monobutyl ether, and the mass ratio of the organic solvent in the organic binder is 60-90%; the mass ratio of the organic auxiliary agent in the organic binder is 0.5-10%, and the organic auxiliary agent comprises one or more of phosphate, phosphate salts, carboxylic acids and high-molecular alkyl ammonium salts. Besides, the slurry is further adjusted and optimized in the performance of the organic binder by other auxiliary agents such as a thixotropic agent and the like, wherein the thixotropic agent comprises one or more of fumed silica, organic bentonite, modified hydrogenated castor oil, span-85 and polyamide wax.

Optimization of the organic binder helps the paste to maintain better printing performance. According to practical tests, the paste can be printed to obtain uniform continuous grid lines with the minimum width of 27 mu m, and the corresponding grid lines have better aspect ratio (about 14%) and morphological characteristics.

Here, we provide examples 1-3 below, and compare them with comparative examples, and a partial cross-sectional view of the back surface of the corresponding PERC cell of example 1 is shown in fig. 2. The comparative examples are conventional slurries, the examples 1 to 3 and the comparative examples are matched with crystalline silicon wafers of the same specification for printing and sintering to obtain corresponding double-sided PERC batteries and are subjected to electrical property tests, and the performance test comparison results of the examples 1 to 3 compared with the comparative examples are shown in the following table 1:

serial number	[Voc(V)]	[Is(A)]	[FF(％)]	[Eff(％)]	[Rs]	[IVRV2]
Example 1	High 3mV	Keep flat	Keep flat	Keep flat	Is higher than the original	Keep flat
Example 2	High 3mV	Is higher than the original	Keep flat	Height of 0.2	Keep flat	Keep flat
Example 3	Low 1mV	Keep flat	Keep flat	Height of 0.1	Is on the low side	Slightly higher

Example 1 the slurry mass composition was: 68 parts of aluminum powder with the particle size of 2-3 mu m; 5 parts of aluminum-silicon alloy powder, wherein the particle size is also 2-3 mu m; 5 parts of silver powder, the particle size is about 0.1-1 μm; 2.5 parts of glass powder, 0.5 part of auxiliary glass powder and 19 parts of organic binder. Wherein the glass powder comprises the following components in percentage by mass: b is₂O₃：ZnO：SiO₂：CaO55: 20: 10: 5: 10, the softening temperature of the glass powder is 290 ℃, and the median particle size is 2.7 mu m. Bi in the auxiliary glass powder₂O₃、B₂O₃And the mass ratio of ZnO is 36: 24: 13, the softening temperature of the auxiliary glass powder is 400 ℃, and the median particle size is 1.4 mu m.

Example 2 the slurry mass composition was: 65 parts of aluminum powder, wherein the aluminum powder specifically comprises two spherical powders with different particle sizes; 12.7 parts of aluminum-silicon alloy powder with the particle size of 2-3 mu m; 1.8 parts of glass powder, 0.5 part of auxiliary glass powder and 20 parts of organic binder. Wherein the glass powder comprises the following components in percentage by mass: b is₂O₃：ZnO：SiO₂：Li₂O: CaO 61: 20: 10: 3: 3: 3, the softening temperature of the glass powder is 320 ℃, and the median particle size is 3.6 mu m. Bi in the auxiliary glass powder₂O₃、B₂O₃And the mass ratio of ZnO is 36: 24: 13, the softening temperature of the auxiliary glass powder is 420 ℃, and the median particle size is 2.2 mu m.

Example 3 the slurry mass composition was: 73 parts of aluminum powder with the particle size of 2-3 mu m; 4.8 parts of aluminum-silicon-boron alloy powder with the particle size of 2-3 mu m; 2.2 parts of glass powder, 0.3 part of auxiliary glass powder and 20 parts of organic binder. Wherein the glass powder comprises the following components in percentage by mass: b is₂O₃：ZnO：SiO₂：Na₂O65: 18: 8: 3: and 6, the softening temperature of the glass powder is 310 ℃, and the median particle size is 2.4 mu m. Bi in the auxiliary glass powder₂O₃、B₂O₃And the mass ratio of ZnO is 70: 20: 10, wherein the softening temperature of the auxiliary glass powder is 390 ℃, and the median particle size is 1.8 mu m.

The invention also provides a preparation method of the slurry, which is shown in figure 3 and comprises the following steps:

weighing corresponding organic resin according to a given proportion, and gradually dissolving and dispersing the organic resin in an organic solvent;

measuring an organic auxiliary agent and other auxiliary agents, and adding the organic auxiliary agent and other auxiliary agents into an organic solvent to obtain an organic binder with uniform texture;

and then adding the aluminum powder, the aluminum alloy powder, the glass powder and the auxiliary glass powder into an organic binder according to a set proportion, mixing, and then grinding and dispersing by a three-roller machine, wherein the fineness of the slurry is not more than 15 mu m.

Referring to fig. 4, the preparation method of the glass powder and the auxiliary glass powder is as follows:

weighing raw materials, uniformly mixing the raw materials, placing the mixture into a constant-temperature drying oven, and drying for 2-5 hours, wherein the temperature of the constant-temperature drying oven is set to be 150-250 ℃;

transferring the dried raw materials into a crucible, and then placing the crucible containing the raw materials into a heating chamber to be smelted according to a set program;

cooling the smelted feed liquid by a cold roll to obtain a glass material;

and crushing and screening the glass frit to obtain glass powder.

Preferably, during smelting, the heating chamber may be charged with a protective gas, such as N₂Or other inert gases to prevent the valence state of the glass frit components from changing, forming more stable compounds; the crucible adopts a platinum crucible to reduce the introduction of impurities. The set program comprises a temperature rise stage and a heat preservation stage, wherein the temperature of the heat preservation stage is set to be 950-1050 ℃, and the duration of the heat preservation stage is set to be 1-2 hours. Except this, adopt jet milling hierarchical screening system to smash and sieve the frit after the cooling to make glass powder, the supplementary glass powder that makes more even, the particle size span is little, can reduce the introduction of impurity simultaneously.

In other embodiments of the present invention, the uniformly mixed raw materials can also be directly filled into the crucible and then dried, thereby reducing intermediate operation processes. The melted feed liquid can be cooled by deionized water and then crushed by ball milling, and the detailed process is not repeated.

In summary, the glass frit has a low softening temperature and a small expansion coefficient, and the prepared paste is suitable for the back metallization process of the PERC cell. The paste can simplify the production process of the PERC battery, does not need laser drilling/grooving or secondary printing, and has wide process adjusting window and stable performance. In addition, the slurry can form better aluminum-silicon contact after being sintered, so that the back surface recombination is effectively controlled, and the electrical property is balanced; the battery piece adopting the slurry has good appearance after sintering, smaller warping and bending and better application prospect.

It should be understood that although the present description refers to embodiments, not every embodiment contains only a single technical solution, and such description is for clarity only, and those skilled in the art should make the description as a whole, and the technical solutions in the embodiments can also be combined appropriately to form other embodiments understood by those skilled in the art.

The above-listed detailed description is only a specific description of a possible embodiment of the present invention, and they are not intended to limit the scope of the present invention, and equivalent embodiments or modifications made without departing from the technical spirit of the present invention should be included in the scope of the present invention.

Claims

The glass powder is used for preparing crystalline silicon solar cell slurry and is characterized by comprising the following components in parts by mass: 30-90 parts of PbO and 5-25 parts of B₂O₃2-10 parts of SiO₂5 to 20 parts of ZnO and 0.1 to 13 parts of M_xO_yWherein M is a first main group element or a second main group element, and the softening temperature of the glass powder is 280-400 ℃.
The glass frit according to claim 1, wherein: the median particle size of the glass powder is 0.5-5 μm.
The glass frit according to claim 1, wherein: the M is_xO_yIs Na₂O、CaO、K₂O and L i₂At least one of O.
The glass frit according to claim 1, wherein: the glass powder also comprises Al₂O₃、CuOAnd P₂O₅At least one of (1).
The glass powder composition is characterized by comprising glass powder and auxiliary glass powder, wherein the glass powder comprises the following components in parts by mass: 30-90 parts of PbO and 5-25 parts of B₂O₃2-10 parts of SiO₂5 to 20 parts of ZnO and 0.1 to 13 parts of M_xO_yWherein M is a first main group element or a second main group element, and the softening temperature of the glass powder is 280-400 ℃; the auxiliary glass powder comprises Bi₂O₃、B₂O₃And ZnO, wherein the softening temperature of the auxiliary glass powder is 380-500 ℃; the mass ratio of the glass powder to the auxiliary glass powder is (1.8-2.2): (0.3-0.5).
The glass frit composition according to claim 5, wherein: the auxiliary glass powder comprises Bi by mass₂O₃：B₂O₃：ZnO＝(3～7)：(1.5～2.5):1。
The glass frit composition according to claim 5, wherein: the auxiliary glass powder also comprises SiO₂、Al₂O₃、CuO、TiO₂、Cr₂O₃、NiO、Li₂O and MnO₂One or more of them.
The glass frit composition according to claim 5, wherein: the median particle size of the auxiliary glass powder is 0.5-5 μm.
A preparation method of glass powder is characterized by comprising the following steps:

weighing raw materials, uniformly mixing the raw materials, and drying for 2-5 hours;

transferring the raw materials subjected to drying treatment into a crucible, and then placing the crucible containing the raw materials into a heating chamber to be smelted according to a set program, wherein the set program comprises a temperature rise stage and a heat preservation stage, the temperature of the heat preservation stage is set to be 950-1050 ℃, and the time of the heat preservation stage is set to be 1-2 hours;

cooling the smelted feed liquid by a cold roll to obtain a glass material;

and crushing and screening the glass frit to obtain glass powder.
The method of claim 9, wherein: the preparation method also comprises the step of filling protective gas into the heating chamber in the smelting process.