WO2024050765A1 - Frit and preparation method, and conductive paste and preparation method - Google Patents

Abstract

The present application relates to the technical field of conductive pastes, in particular relates to a frit and a preparation method, and a conductive paste and a preparation method, and can be applied to an N-type TOPCon crystalline silicon solar cell. The present application provides a frit on the first aspect. The frit comprises the following components in percentages by mole of oxides: 20-49% of PbO, 10-30% of SiO2, 15-35% of B2O3, 5-15% of ZnO, 0-10% of a first alkaline earth metal oxide and 0.1-5% of an alkali metal oxide. The frit provided in the present application can reduce the glass transition temperature thereof by means of a mixed alkali effect of the alkali metal oxide. Since the frit provided in the present application has a low glass transition temperature, when the frit is applied to a conductive paste, the silver dissolving and separating capacity of the frit under low-temperature conditions can be improved, and the problem of being impossible to metalize a TOPCon crystalline silicon battery at a low temperature is solved.

Description

Glass frit and preparation method, conductive paste and preparation method Technical field

The present application belongs to the technical field of conductive slurries, and in particular relates to a glass frit and a preparation method, conductive slurry and a preparation method.

Background technique

In the field of photovoltaic energy, crystalline silicon is the most commonly used material for preparing solar cells due to its high efficiency, low cost and rich properties. For solar cells based on crystalline silicon, minority carrier recombination at the metal-semiconductor interface has always been considered the most critical challenge in achieving high-efficiency silicon solar cells. The traditional aluminum backfield solar cell structure has high interface defects at the metal-semiconductor junction, resulting in high recombination loss and efficiency loss. The tunnel oxide passivated contact (TOPCon) structure can effectively extract majority carriers while suppressing the recombination of minority carriers, and is currently the most effective method to achieve this performance improvement.

The mechanism of improving the photoelectric conversion efficiency of the Poly-si passivation layer is mainly aimed at increasing the open circuit voltage (Voc) of the battery. At the same time, one of the purposes of adding a small amount of metal aluminum powder to the slurry is to reduce the shunt and recombination effects of N-type solar cells. Both performance improvements require front-side slurries with lower metallization sintering temperatures.

The TOPCon cell structure based on N-type silicon uses the Poly-si passivation layer to achieve excellent carrier selectivity, low contact resistivity and low surface recombination, overcoming the limitations of metal-silicon interface recombination. The current record of photoelectric conversion efficiency in the N-type TOPCon battery laboratory has reached 26.0% (Fraunhofer ISE). For the front silver paste, the ohmic contact mechanism of the N-type p ⁺ emitter is the same as that of the n ⁺ emitter. They are both based on the instant silver dissolving ability of the glass frit after high-temperature sintering and the tunneling formed by the precipitation of nano-silver particles in the cooling section. effect.

technical problem

The technical problem to be solved by this application is to provide a glass frit and a preparation method, aiming to solve the problem that the existing glass frit has poor low-temperature silver dissolving and silver precipitation ability, and the TOPCon crystalline silicon battery cannot be metallized at low temperature.

Furthermore, this application also provides a conductive paste and a preparation method.

Technical solutions

In order to achieve the above-mentioned object of the invention, the technical solutions adopted in this application are as follows:

A kind of glass frit, the glass frit contains the following components in terms of oxide mole percentage:

20~49% PbO;

10~30% SiO ₂ ;

15~35% B ₂ O ₃ ;

5~15% ZnO;

0~10% The first alkaline earth metal oxide;

0.1~5% Alkali metal oxides.

Correspondingly, a method for preparing glass frit includes the following steps:

Obtain the components contained in any one of the mixed alkali lead borosilicate glass frit, lead borosilicate glass frit and alkaline glass frit. Weigh each glass raw material and perform a mixing process to obtain a glass raw material mixture;

The glass raw material mixture is melted to obtain molten glass;

Water-quenching the glass liquid to obtain glass particles;

The glass particles are ground and classified to obtain glass frit.

And, a conductive slurry for N-type TOPCon crystalline silicon solar cells , including conductive metal powder and organic carrier, and also includes the above-mentioned glass frit or the glass frit prepared by the above-mentioned glass frit preparation method.

Correspondingly, a method for preparing conductive slurry includes the following steps:

The glass frit, organic carrier, metal silver powder and metal aluminum powder are mixed to obtain a conductive slurry.

beneficial effects

Compared with the existing technology, the glass frit provided by this application is prepared by adjusting the compound ratio of PbO, SiO ₂ , B ₂ O ₃ , ZnO, the first alkaline earth metal oxide and the alkali metal oxide, and through the mixed alkali of the alkali metal oxide. effect, which can lower its glass transition temperature. Precisely because the glass frit provided by this application has a lower glass transition temperature, when it is used in conductive paste, it can reduce the sintering temperature of the conductive paste and improve the ability of the glass frit to dissolve silver and precipitate silver under low temperature conditions. , solves the problem of low-temperature metallization of TOPCon crystalline silicon cells, and improves the overall performance of the conductive slurry, such as improving the cell's (Voc), contact resistance (Rc) and photoelectric conversion efficiency (Eta).

The preparation method of glass frit provided in this application is mainly divided into four steps. In the first step, each glass raw material is weighed according to the components contained in the glass frit in the above article, and the glass transition temperature of the glass frit in the above article can be adjusted. By mixing each of the glass raw materials mentioned above, a highly dispersed glass raw material mixture can be obtained. In the second step, the glass raw material mixture is melted to form liquid glass. In the third step, the glass liquid is quenched with water to solidify the glass liquid to obtain glass particles. The fourth step is to grind and classify the glass particles to obtain glass frit with a preset particle size, which can be used in conductive silver paste.

The conductive metal powder and glass frit provided in the above embodiments of the present application are combined to form a conductive slurry. The conductive metal powder imparts conductive properties to the conductive slurry, and the glass frit is dispersed in the conductive metal particles. During the subsequent sintering process, the low temperature of the glass The ability to dissolve silver and precipitate silver makes the conductive paste suitable for low-temperature sintering. It is beneficial to increase the open circuit voltage (Voc) and fill factor (FF) of TOPCon cells, thereby improving the conversion efficiency of solar cells and reducing the cost of electricity. Furthermore, the glass frit in the above article includes a mixed alkali lead borosilicate glass frit or a combination of lead borosilicate glass frit and alkaline glass frit. Both conductive pastes can effectively improve the photoelectric conversion efficiency of solar cells and reduce kWh. cost.

The conductive slurry formed by the combination of glass frit, conductive metal powder and organic carrier provided by the above application. The glass frit realizes the sintering and ohmic contact functions of the conductive metal powder. The conductive metal powder imparts conductive properties to the conductive slurry. The organic carrier realizes the conductive slurry. It improves the use function of conductive paste and facilitates screen printing of conductive paste to form a conductive layer. Further, the glass frit in the above article includes a mixed alkali lead borosilicate glass frit or a combination of lead borosilicate glass frit and alkaline glass frit. Both conductive pastes can effectively improve the photoelectric conversion efficiency of solar cells and reduce the degree of degradation. Electricity costs.

Embodiments of the invention

In order to make the technical problems, technical solutions and beneficial effects to be solved by this application clearer, this application will be further described in detail below in conjunction with examples. It should be understood that the specific embodiments described here are only used to explain the present application and are not used to limit the present application.

In this application, the term "and/or" describes the relationship between related objects, indicating that there can be three relationships. For example, A and/or B can mean: A exists alone, A and B exist simultaneously, and B exists alone. Condition. Where A and B can be singular or plural. The character "/" generally indicates that the related objects are in an "or" relationship.

In this application, "at least one" refers to one or more, and "plurality" refers to two or more. “At least one of the following” or similar expressions refers to any combination of these items, including any combination of single items (items) or plural items (items). For example, "at least one of a, b, or c", or "at least one of a, b, and c" can mean: a, b, c, a-b ( That is, a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple respectively.

It should be understood that in various embodiments of the present application, the size of the sequence numbers of the above-mentioned processes does not mean the order of execution. Some or all steps can be executed in parallel or one after another. The execution order of each process should be based on its function and order. The internal logic is determined and should not constitute any limitation on the implementation process of the implementation regulations of this application.

The terminology used in the embodiments of this application is only for the purpose of describing specific implementation regulations and is not intended to limit this application. As used in this specification and the appended claims, the singular forms "a," "the" and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise.

The weights of relevant components mentioned in the description of the embodiments of the present application may not only refer to the specific content of each component, but also represent the proportional relationship of weight between the components. Therefore, as long as the relevant components are combined according to the description of the embodiments of the present application, Any scaling up or down of the content is within the scope disclosed in the examples of this application. Specifically, the mass described in the description of the embodiments of this application may be mass units well-known in the chemical industry such as µg, mg, g, kg, etc.

The terms first and “second” are used for descriptive purposes only and are used to distinguish objects such as substances from each other, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of indicated technical features. For example, without departing from the scope of the implementation regulations of this application, the first XX may also be called the second XX, and similarly, the second XX may also be called the first XX. Therefore, features defined as "first" and "second" may explicitly or implicitly include one or more of these features.

The first aspect of the embodiment of the present application provides a glass frit. The glass frit contains the following components in terms of oxide mole percentage:

20~49% PbO;

10~30% SiO ₂ ;

15~35% B ₂ O ₃ ;

5~15% ZnO;

0~10% The first alkaline earth metal oxide;

0.1~5% Alkali metal oxides.

The glass frit provided in the embodiments of the present application is made by adjusting the compound ratio of components such as PbO, SiO ₂ , B ₂ O ₃ , ZnO, the first alkaline earth metal oxide, and the alkali metal oxide calculated as oxides. The mixed alkali effect can lower its glass transition temperature. Precisely because the glass frit provided in the embodiments of the present application has a lower glass transition temperature, when used in conductive paste, the sintering temperature of the conductive paste can be reduced, and the ability of the glass frit to dissolve silver and precipitate under low temperature conditions can be improved. The silver ability solves the problem of low-temperature metallization of TOPCon crystalline silicon cells and improves the overall performance of the conductive paste, such as improving the battery (Voc), contact resistance (Rc) and photoelectric conversion efficiency (Eta). Among them, the glass frit provided in the embodiment of the present application is used in TOPCon crystalline silicon cells. The front-side photoelectric conversion efficiency (Eta) of TOPCon crystalline silicon cells is comparable to overseas DuPont PV series products. In addition, the content of the alkali metal oxide provided in the embodiments of the present application can improve the electrical properties of the conductive silver paste, which is mainly manifested in higher open circuit voltage (Voc).

In some embodiments, the glass frit includes mixed alkali lead borosilicate glass frit. Further, the glass frit in the above article includes mixed alkali lead borosilicate glass frit, which is composed of: 20~49% PbO, 10~30% SiO ₂ , 15~35% B ₂ O ₃ , based on the molar percentage of oxides. 5~15% ZnO, 0~10% first alkaline earth metal oxide, 0.1~5% alkali metal oxide.

In some embodiments, the glass frit includes lead borosilicate glass and alkaline glass frit used in combination, wherein lead borosilicate glass and alkaline glass frit are two different glass frits, both of which are prepared separately and need to be used during use. When used together, the sum of the superimposed components of lead borosilicate glass frit and alkaline glass frit is calculated based on oxide mole percentage: 20~49% PbO, 10~30% SiO ₂ , 15~35% B ₂ O ₃ , 5~15% ZnO, 0~10% first alkaline earth metal oxide, 0.1~5% alkali metal oxide. The embodiment of this application uses a combination of two glass frits. The mass ratio of the alkaline glass frit and the lead borosilicate glass frit is (1:2) ~ (1:10), and the lead borosilicate glass frit is used as the main glass frit. Alkaline glass frit is used as auxiliary glass frit in combination. In the above text, the mass ratio of the alkali glass frit and the lead borosilicate glass frit may be 1:5, but is not limited thereto.

In some embodiments, the raw material of the first alkaline earth metal oxide includes at least one of oxides, carbonates, nitrates and chlorides containing the first alkaline earth metal element, wherein the first alkaline earth metal element includes Mg, At least one of Ca, Sr and Ba.

In some embodiments, the raw material of alkali metal oxides includes at least one of oxides, chlorides, nitrates and carbonates of alkali metal elements, wherein the alkali metal elements include at least one of Li, Na, and K. kind. In the above article, the morphology of the raw material of alkali metal oxide is granular, micron-scale powder or nano-scale powder. Embodiments of the present application can utilize the mixed alkali effect of the alkali metal elements Li, Na, and K to adjust the glass transition temperature of the glass, enhance the low-temperature silver dissolving ability of the glass, and make the conductive paste suitable for low-temperature sintering. It is beneficial to increase the open circuit voltage (Voc) and fill factor (FF) of TOPCon cells, thereby improving the photoelectric conversion efficiency (Eta) of solar cells and reducing the cost of electricity.

The second aspect of the embodiments of the present application provides a method for preparing glass frit, which includes the following steps:

Step S10: Obtain the components contained in any one of the mixed alkali lead borosilicate glass frit, lead borosilicate glass frit and alkaline glass frit, weigh each glass raw material, and perform a mixing process to obtain a glass raw material mixture;

Step S20: melt the glass raw material mixture to obtain molten glass;

Step S30: Perform water quenching treatment on the glass liquid to obtain glass particles;

Step S40: Grind and classify the glass particles to obtain glass frit.

The preparation method of glass frit provided in the embodiments of this application is mainly divided into four steps. The first step is to obtain the components contained in any of the mixed alkali lead borosilicate glass frit, lead borosilicate glass frit and alkaline glass frit. Weigh each glass raw material to adjust the glass transition temperature of the glass frit mentioned above. By mixing each of the glass raw materials mentioned above, a highly dispersed glass raw material mixture can be obtained. In the second step, the glass raw material mixture is melted to form liquid glass. In the third step, the glass liquid is quenched with water to solidify the glass liquid to obtain glass particles. The fourth step is to grind and classify the glass particles to obtain glass frit with a preset particle size, which can be used in conductive silver paste.

In the above step S10, the glass frit mentioned above includes any one of mixed alkali lead borosilicate glass frit, lead borosilicate glass or alkaline glass frit. The formed mixed alkali lead borosilicate glass frit, lead borosilicate glass frit or Glass transition temperature of alkaline glass frit. The melting temperature of the above-mentioned lead borosilicate glass frit is 1000~1150℃, the melting temperature of the alkaline glass frit is 800~1000℃, and the melting time is 20 minutes. The solute temperature and melting time of the alkaline glass frit are shorter than the main Glass frit (lead borosilicate glass frit), the reason is that the formula based on the alkaline glass frit is designed as a low melting point glass frit, and the liquid glass has trace volatility at high temperatures.

In some embodiments, the glass transition temperature of the mixed alkali lead borosilicate glass frit is 305~350°C. Compared with traditional glass frits, the mixed alkali lead borosilicate glass frit provided in the embodiments of the present application has a lower glass transition temperature. transformation temperature.

In some embodiments, the alkaline glass frit is prepared and formed by the following steps:

The raw materials of the alkali metal oxide and the raw materials corresponding to the components of other alkaline glass frits are mixed to obtain an alkaline glass raw material mixture. In the above article, the average particle size of the alkaline glass frit is 2~4 μm, and the maximum particle size Dmax is <5 μm.

In some embodiments, the raw materials of alkali metal oxides include Li ₂ CO ₃ , K ₂ CO ₃ , and Na ₂ CO ₃ , and the alkaline glass frit contains the following components in terms of oxide mole percentage:

5~15% Li ₂ O;

1~10% Na ₂ O;

1~10% K ₂ O;

10~30% SiO ₂ ;

5~20% B ₂ O ₃ ;

5~20% ZnO;

0~10% Second alkaline earth metal oxide.

In the embodiments of the present application, by adjusting the compound ratio of Li ₂ O, Na ₂ O, K ₂ O, SiO ₂ , B ₂ O ₃ , ZnO, and the second alkaline earth metal oxide, a melting temperature of 800 to 1000°C can be obtained. Alkaline glass frit. In specific embodiments, the raw materials of alkali metal oxides include Na ₂ CO ₃ and Li ₂ CO ₃ , wherein the mass ratio of Na ₂ CO ₃ and Li ₂ CO ₃ can be 1:1, 4:3, or 4:2. , 3:4, 2:4, 10:16, 16:10. Among them, when the ratio is 1:1, the electrical performance is the best.

In some embodiments, the lead borosilicate glass frit is prepared and formed by the following steps:

The raw materials of lead oxide and other raw materials corresponding to the components of the lead borosilicate glass frit are mixed to obtain a lead borosilicate glass frit mixture.

In some embodiments, the raw material of lead oxide includes Pb ₃ O ₄ . In the embodiments of the present application, by adjusting the compound ratio of SiO ₂ , B ₂ O ₃ , ZnO, and PbO, the melting temperature can be obtained to a melting temperature of 1000 to Lead borosilicate glass frit at 1150℃. In specific embodiments, the raw material of lead borosilicate glass frit contains the following mass ratios of each component: 71% Pb ₃ O ₄ , 16% SiO ₂ , 6% B ₂ O ₃ , 7% ZnO, but is not limited to this.

In some embodiments, the raw material of the second alkaline earth metal oxide includes at least one of oxides, carbonates, nitrates and chlorides containing the second alkaline earth metal element, wherein the second alkaline earth metal element includes Mg, At least one of Ca, Sr and Ba.

In some embodiments, the grinding process includes ball milling. In some embodiments, the glass frit with a predetermined particle size can be obtained by performing a classification process in an airflow mill. Wherein, the glass frit includes any one of mixed alkali lead borosilicate glass frit, lead borosilicate glass or alkaline glass frit.

The third aspect of the embodiment of the present application provides a conductive slurry for N-type TOPCon crystalline silicon solar cells , including conductive metal powder and an organic carrier, and also includes the above-mentioned glass frit or the glass prepared by the above-mentioned glass frit preparation method. material.

The conductive slurry is formed by compounding the glass frit, conductive metal powder and organic carrier provided in the above embodiments of the present application. The conductive metal powder imparts conductive properties to the conductive slurry. The glass frit is dispersed in the conductive metal powder. During the subsequent sintering process, Realize the ability of glass to dissolve silver and precipitate silver at low temperature, making the conductive paste suitable for low-temperature sintering. It is beneficial to increase the open circuit voltage (Voc) and fill factor (FF) of TOPCon cells, thereby increasing the conversion efficiency (Eta) of solar cells and reducing the cost of electricity. Furthermore, the glass frit in the above article includes a mixed alkali lead borosilicate glass frit or a combination of lead borosilicate glass frit and alkaline glass frit. Both conductive slurries can reduce the metallization sintering temperature of the conductive slurry and improve The photoelectric conversion efficiency (Eta) of solar cells reduces the cost of electricity.

In some embodiments, the conductive metal powder includes aluminum powder and silver powder, and the conductive paste includes the following mass percentages of each component:

2~5wt % Glass frit;

7~13wt % organic carrier;

1~3wt% Aluminum powder;

80~90wt% Silver powder.

The conductive metal powder provided in the above embodiments of the present application includes aluminum powder and silver powder, which can reduce the shunt and recombination effects of N-type solar cells. The conductive slurry formed by compounding with the organic carrier, the aluminum powder and silver powder impart conductive properties to the conductive slurry. , aluminum powder and silver powder are dispersed in the organic carrier, which can adjust the viscosity of the slurry, which is beneficial to the printing of materials, and facilitates the coating process of the conductive slurry to form a conductive layer. In the subsequent sintering process, the glass frit can reduce the conductivity The metallization sintering temperature of the slurry enhances the low-temperature silver melting ability of the glass. By adjusting the compound ratio of glass frit, organic carrier, aluminum powder and silver powder, the open circuit voltage (Voc) and fill factor (FF) of the TOPCon battery can be further increased, thereby improving the photoelectric conversion efficiency (Eta) of the solar cell and reducing the kWh cost. Furthermore, the glass frit in the above article includes a mixed alkali lead borosilicate glass frit or a combination of lead borosilicate glass frit and alkaline glass frit. Both conductive slurries can reduce the metallization sintering temperature of the conductive slurry and improve The photoelectric conversion efficiency (Eta) of solar cells reduces the cost of electricity.

In some embodiments, the metallic silver powder includes micron-sized spherical, spherical-like and nano-sized silver powder. The particle size of the micron silver powder in the above article includes at least one of the three grades of 1~2μm, 2~4μm and 4~6μm. The three grades of micron silver powder mentioned above can be used in any proportion. It can improve the dispersion and stacking density of the conductive paste, help improve the sintering density of the silver layer, and reduce the line resistance of the silver fine gate.

In some embodiments, the fineness of the conductive paste is 3~5 μm, and the viscosity is 80~180 Pa·s under the measurement condition of 25°C, which is convenient for printing.

The fourth aspect of the embodiments of the present application provides a method for preparing conductive slurry, which includes the following steps:

Step S50: Mix glass frit, organic carrier, metal silver powder and metal aluminum powder to obtain conductive slurry.

The conductive slurry formed by the compounding of glass frit, conductive metal powder and organic carrier provided in the above embodiments of the present application, the glass frit realizes the sintering and ohmic contact functions of the conductive metal powder, the conductive metal powder imparts conductive properties to the conductive slurry, and the organic carrier The carrier realizes the use function of the conductive paste and facilitates screen printing of the conductive paste to form a conductive layer. Among them, the conductive paste provided in the embodiment of the present application can be used as an N-type TOPCon front-side paste. The glass frit, metallic silver powder and metallic aluminum powder in the above article are mixed and dispersed in an organic carrier. Under low temperature conditions, it can improve the sintering ability of N-type TOPCon front slurry to dissolve silver and precipitate silver, thereby reducing the shunt and recombination effects of N-type solar cells. , ultimately increasing the open circuit voltage (Voc) of the battery. Furthermore, the glass frit in the above article includes a mixed alkali lead borosilicate glass frit or a combination of lead borosilicate glass frit and alkaline glass frit. Both conductive pastes can effectively improve the photoelectric conversion efficiency of solar cells. Reduce electricity costs.

In some embodiments, in the above-mentioned step S50, the mixing process includes mixing glass frit, organic carrier, metallic silver powder and metallic aluminum powder through high-speed centrifugal processing, and rolling through a three-roller mill to obtain a conductive slurry.

In order to make the above implementation details and operations of the present application clearly understood by those skilled in the art, and to significantly reflect the improved performance of the glass frits and preparation methods, conductive pastes and preparation methods of the embodiments of the present application, multiple examples are provided below. Give an example to illustrate the above technical solution.

Example 1

This embodiment provides a method for preparing mixed alkali lead borosilicate glass frit, which includes the following steps:

Step S10: Weigh according to the formula with a mass ratio of Pb ₃ O ₄ : Li ₂ CO ₃ : SiO ₂ : B2O ₃ : ZnO: Na ₂ CO ₃ : K ₂ CO ₃ of 67:4:14:5:6:4. Raw materials of glass frit:

Step S20: Mix the weighed raw materials thoroughly in a mixer and place them in a platinum crucible. Then place the crucible in a muffle furnace and keep it at 900~1150°C for 20~40 minutes for melting;

Step S30: Rapidly pour the molten glass liquid into deionized water for water quenching to obtain glass particles of about 1mm;

Step S40: Put the obtained glass particles into a ball milling tank, dry ball mill according to the preset ball-to-material ratio for 1 to 2 hours, and finally introduce the crude glass frit into the airflow mill according to a certain feed amount, and finally obtain the mixed alkali lead and boron Silica glass frit.

Example 2 to Example 11

The preparation method of the mixed alkali lead borosilicate glass frit in Examples 2 to 11 is the same as that in Example 1. The difference lies in the proportion of each raw material of the mixed alkali lead borosilicate glass frit. The specific proportions are shown in Table 1.

Example 12

This embodiment provides a method for preparing lead borosilicate glass frit, which includes the following steps:

Step S10: Weigh the raw materials of the glass frit according to the formula of Pb ₃ O ₄ : SiO ₂ : B ₂ O ₃ : ZnO with a mass ratio of 71:16:6:7:

Step S20: Mix the weighed raw materials thoroughly in a mixer and place them in a platinum crucible. Then place the crucible in a muffle furnace and keep it at 900~1150°C for 20~40 minutes for melting;

Step S30: Rapidly pour the molten glass liquid into deionized water for water quenching to obtain glass particles of about 1mm;

Step S40: Put the obtained glass particles into a ball milling tank, dry ball mill according to the preset ball-to-material ratio for 1 to 2 hours, and finally introduce the crude glass frit into the airflow mill according to a certain feed amount, and finally obtain the required lead and boron. Silica glass frit.

Example 13

This embodiment provides a method for preparing alkaline glass frit, which includes the following steps:

Step S10: Weigh the raw materials of the glass frit according to the formula of Li ₂ CO ₃ : SiO ₂ : B ₂ O ₃ : ZnO: Na ₂ CO ₃ mass ratio of 13:37:22:15:13:

Step S20: Mix the weighed raw materials thoroughly in a mixer and place them in a platinum crucible. Then place the crucible in a muffle furnace and keep it at 900~1150°C for 20~40 minutes for melting;

Step S30: Rapidly pour the molten glass liquid into deionized water for water quenching to obtain glass particles of about 1mm;

Step S40: Put the obtained glass particles into a ball milling tank, and dry ball mill them according to the preset ball-to-material ratio for 1 to 2 hours. Finally, introduce the crude glass frit into the airflow mill according to a certain feed amount, and finally obtain the required alkalinity. Glass frit.

Example 14 to Example 21

The preparation method of the alkaline glass frit in Examples 14 to 21 is the same as that in Example 13. The difference lies in the ratio of the raw materials of the glass frit. The specific proportions are shown in Table 1.

Example 22

This embodiment provides a method for preparing N-type TOPCon front-side silver-aluminum paste, which includes the following steps:

Step S50: Weigh each component according to the formula with a mass ratio of glass frit, metal silver material, metal aluminum material, organic additive and organic carrier of 6:83.8:2:0.2:8 in Example 1.

Step S60: Mix the glass frit, organic carrier, metallic silver material and metallic aluminum material evenly through high-speed centrifugation and then homogenize and grind them multiple times with a three-roller machine to obtain a silver-aluminum slurry. This production process controls the fineness of the silver aluminum paste to be 3~5μm and the viscosity to be 80~180 Pa·s.

Example 23 to Example 42

The preparation methods of the N-type TOPCon front-side silver-aluminum paste in Examples 23 to 42 are the same as those in Example 22. The difference lies in the components and proportion of the glass frit. The specific proportions are shown in Table 2.

Comparative example 1

DuPont PV series of silver paste.

Performance Testing

Table 1 lists the results of a single mixed alkali lead borosilicate glass frit (Example 1 to Example 11) and a combination of lead borosilicate glass frit (Example 13 to Example 21) and an alkali glass frit (Example 12). Component design examples, A1~A11 are examples of mixed alkali lead borosilicate glass frit component design; B1 is an example of lead borosilicate glass frit design (Example 12) using two glass frit combination solutions, C1~C9 are alkali Examples of design of flexible glass frit components. The glass raw materials selected in the embodiments of this application all use oxides or carbonates of corresponding elements.

Table 2 shows the production ratio of silver-aluminum paste based on each glass frit listed in Table 1. The glass frits used in Examples 22 to 32, 33 and 34 to 42 in Table 2 respectively correspond to the A1 to A11, B1 and C1 to C9 glass frits listed in Table 1.

Table 1 The raw material ratio of each glass frit

serial number Glass frit type Each component of glass frit wt.% Pb3O4 Li2CO3 SiO2 B2O3 ZnO Na2CO3 K2CO3 Example 1 A1 67 4 14 5 6 4 ​ Example 2 A2 68 4 14 5 6 3 ​ Example 3 A3 69 4 14 5 6 2 ​ Example 4 A4 68 3 14 5 6 4 ​ Example 5 A5 69 2 14 5 6 4 ​ Example 6 A6 67 3 14 5 6 3 2 Example 7 A7 67 4 14 5 6 ​ 4 Example 8 A8 67 ​ 14 5 6 4 4 Example 9 A9 68 4 14 5 9 ​ ​ Example 10 A10 68 ​ 14 5 9 4 ​ Example 11 ​ A11 68 ​ 14 5 9 ​ 4 Example 12 B1 71 ​ 16 6 7 ​ ​ Example 13 C1 ​ 13 37 twenty two 15 13 ​ Example 14 C2 ​ 10 37 twenty two 15 16 ​ Example 15 C3 ​ 16 37 twenty two 15 10 ​ Example 16 C4 ​ 8.5 38 twenty two 15 8.5 8.5 Example 17 C5 ​ ​ 37 twenty two 15 13 13.0 Example 18 C6 ​ 13 37 twenty two 15 ​ 13 Example 19 C7 ​ ​ 42 27 18 13 ​ Example 20 C8 ​ 13 42 27 18 ​ ​ Example 21 C9 ​ ​ 42 27 18 ​ 13

Table 2 TOPCon silver aluminum paste ratio

The TOPCon silver-aluminum pastes of the examples listed in Table 2 and Comparative Example 1 were screen printed, metallized, sintered and tested on N-type TOPCon crystalline silicon cells.

(1) Screen-print the TOPCon silver aluminum paste in Example 22 to Example 42 and the silver paste in Comparative Example 1 on N-type TOPCon crystalline silicon cells, and conduct an electrical performance test. The test results are shown in Table 3.

table 3 TOPCon silver aluminum paste electrical performance parameters

serial number Type of glass frit Electrical performance test data Uoc(V) Isc(A) FF(%) Rs(Ω) Rsh(Ω) Eta(%) Example 22 A1 0.7100 10.238 75.03 0.196 5430 23.25 Example 23 A2 0.7094 10.059 75.01 0.065 6495 23.09 Example 24 A3 0.6995 10.205 74.98 0.063 286 23.01 Example 25 A4 0.7116 13.600 74.33 0.005 3716 22.61 Example 26 A5 0.7096 13.662 73.58 0.005 3648 22.42 Example 27 A6 0.7138 13.629 72.03 0.006 3957 22.03 Example 28 A7 0.7080 13.589 72.30 0.006 2543 21.86 Example 29 A8 0.7114 13.747 73.19 0.005 4191 21.70 Example 30 A9 0.7090 13.646 72.71 0.005 2844 21.33 Example 31 A10 0.7032 13.652 73.07 0.005 1166 21.27 Example 32 A11 0.7088 10.218 71.22 0.064 11847 20.85 Example 33 B1 0.7059 13.599 71.56 0.006 2659 20.82 Example 34 B1+C1 0.7103 10.228 74.99 0.196 5430 23.23 Example 35 B1+C2 0.6994 10.100 72.39 0.065 2302 22.85 Example 36 B1+C3 0.6981 10.138 72.28 0.062 2203 22.56 Example 37 B1+C4 0.7038 13.591 72.44 0.005 2687 21.01 Example 38 B1+C5 0.7107 10.197 71.09 0.064 4105 20.91 Example 39 B1+C6 0.7124 10.214 71.00 0.064 5330 20.88 Example 40 B1+C7 0.7023 13.606 71.87 0.005 2496 20.82 Example 41 B1+C8 0.7058 13.653 71.25 0.006 2513 20.82 Example 42 B1+C9 0.7039 10.434 71.25 0.167 10159 20.81 Comparative example 1 DuPont PV series 0.7110 10.188 75.02 0.227 5233 23.24

Among them, the combined ratio of mixed alkali lead borosilicate glass frit, lead borosilicate glass frit and alkaline glass frit is shown in Table 2. The mixed alkali effect can be achieved by a single mixed alkali lead borosilicate glass frit (Example 22 to Example 32) or a combination of lead borosilicate glass frit (Example 34 to Example 42) and an alkali glass frit (Example 33).

A single glass frit is mixed with alkali lead borosilicate glass frit. In Examples 22 to 32, the electrical performance test conversion efficiency Eta is higher than 21.27%. In Examples 22 to 32, TOPCon contains mixed alkali lead borosilicate glass frit. Silver aluminum paste can effectively improve the photoelectric conversion efficiency of solar cells and reduce the cost of electricity. Among them, the electrical performance test conversion efficiency Eta is equivalent to Comparative Example 1 for Example 22.

In Examples 22 to 32 based on mixed alkali lead borosilicate glass frit, when the mixed alkali (Li ₂ CO ₃ : Na ₂ CO ₃ ) ratio is 4:4, the electrical performance is the best, as shown in Table 3 The electrical properties of Example 22 are comparable to Comparative Example 1. If the content of any alkali metal oxide raw material (Li ₂ CO ₃ , Li ₂ CO ₃ or Na ₂ CO ₃ in Table 1) is too high or too low, the TOPCon will be seriously reduced. The electrical properties of silver aluminum paste are mainly manifested in low open circuit voltage Voc.

For the lead borosilicate glass frit and alkali glass frit used in combination, in Examples 34 to 42, the electrical performance test conversion efficiency Eta is higher than 20.81%. Examples 34 to 42 contain lead borosilicate glass frit and alkali. TOPCon silver-aluminum paste with high-performance glass frit can effectively improve the photoelectric conversion efficiency of solar cells and reduce the cost of electricity. Among them, the electrical performance test conversion efficiency Eta is equivalent to that of Comparative Example 1 in Example 34.

In Examples 34 to 42 that utilize two kinds of glass frits (lead borosilicate glass frit B1 + alkaline glass frit C1~C9), the alkaline glass frit is mixed with alkali (Li ₂ CO ₃ : Na ₂ CO ₃ ). The performance is optimal when the ratio is 13:13. As shown in Table 3, the electrical performance of the TOPCon silver aluminum paste in Example 34 is equivalent to that of the TOPCon silver paste in Comparative Example 1.

The electrical properties of the TOPCon silver-aluminum paste containing only lead borosilicate glass frit (Example 33) are significantly lower than those of the TOPCon silver-aluminum paste in Example 22, the TOPCon silver-aluminum paste in Example 34, and the prepared TOPCon silver-aluminum paste. Silver paste in scale 1.

(2) Screen-print the TOPCon silver aluminum paste in Examples 22 to 42 and the silver paste in Comparative Example 1 on N-type TOPCon crystalline silicon cells, and perform a low-temperature sintering performance test. The test results are shown in Table 4.

Table 4 Differences in electrical properties of high and low temperature sintering of TOPCon silver aluminum paste

At the same time, for Example 22 and Example 34, The electrical properties of TOPCon silver aluminum paste and the silver paste in Comparative Example 1 were tested at different metallization sintering temperatures. The sintering furnace is the Despatch infrared chain furnace commonly used in the industry. Set different peak temperatures of the sintering furnace, and conduct performance tests on the TOPCon silver-aluminum paste in Example 22 and Example 34 and the silver-aluminum paste in Comparative Example 1. The test results are shown in Table 4. The electrical performance parameters of the TOPCon silver-aluminum pastes in Example 22 and Example 34 of the present application are basically the same under the conditions of high temperature 740°C and low temperature 725°C, while the silver paste in Comparative Example 1 has a higher Eta attenuation under low-temperature sintering conditions. larger under the conditions.

At the same time, as theoretical support for the low-temperature sintering performance of mixed alkali lead borosilicate glass frits, this application tested the Tg (softening point) of the glass frits in Examples 1 to 21 listed, and at the same time, the key process parameters for the production of each glass frit were tested. A summary is made, as shown in Table 5.

table 5 Glass material physical and chemical properties

In Example 1 to Example 21, the Tg of the lead borosilicate glass frit in Example 12 has the highest Tg of 351°C. The Tg of the lead borosilicate glass frit in Example 1 to Example 12 are all lower than those in the Example. 12 Tg of lead borosilicate glass frit. Compared with the Tg of the lead borosilicate glass frit in Example 12, the above data confirms that the mixed alkali lead borosilicate glass frit (Example 1 to Example 11) provided by the present application is beneficial to realizing low-temperature sintering of the silver-aluminum paste system. .

In Examples 1 to 11, the Tg of the mixed alkali lead borosilicate glass frit in Example 1 has the lowest Tg of 319°C, and the Tg of the alkaline glass frits in Examples 13 to 21 are all lower than For the mixed alkali lead borosilicate glass frit in Example 1, the above data confirms that the alkaline glass frit (Example 13 to Example 21) provided by this application has good low-temperature sintering performance and can be used as an auxiliary material, which is beneficial to the realization of the combination Low-temperature sintering of silver-aluminum paste systems using lead borosilicate frit and alkaline frit glasses.

In summary, the two TOPCon silver-aluminum pastes prepared from the three types of lead borosilicate glass frits, the mixed alkali lead borosilicate glass frit, and the alkaline glass frit provided in the above article have good electrical properties and low-temperature sintering properties.

The above are only preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application shall be included in the protection of the present application. within the range.

Claims (20)

A glass frit, characterized in that the glass frit contains the following components in terms of oxide mole percentage: 20~49% PbO; 10~30% SiO ₂ ; 15~35% B ₂ O ₃ ; 5~15% ZnO; 0~10% First alkaline earth metal oxide; 0.1~5% Alkali metal oxides. The glass frit of claim 1, wherein the glass frit includes a mixed alkali lead borosilicate glass frit or a combination of lead borosilicate glass frit and alkaline glass frit. The glass frit of claim 1, wherein the raw material of the first alkaline earth metal oxide includes at least one of oxides, carbonates, nitrates and chlorides containing the first alkaline earth metal element, wherein , the first alkaline earth metal element includes at least one of Mg, Ca, Sr, and Ba. The glass frit of claim 1, wherein the raw material of the alkali metal oxide includes at least one of oxides, chlorides, nitrates and carbonates of alkali metal elements, wherein the alkali metal The element includes at least one of Li, Na, and K. The glass frit of claim 2, wherein the glass transition temperature of the mixed alkali lead borosilicate glass frit is 305 to 350°C. The glass frit according to claim 2, characterized in that the average particle size of the alkaline glass frit is 2 to 4 μm, and the maximum particle size Dmax is <5 μm. The glass frit of claim 2, characterized in that the mass ratio of the alkaline glass frit and lead borosilicate glass frit is (1:2) to (1:10). A method for preparing glass frit, characterized in that it includes the following steps: Obtain the components contained in any one of the mixed alkali lead borosilicate glass frit, lead borosilicate glass frit and alkaline glass frit. Weigh each glass raw material and perform a mixing process to obtain a glass raw material mixture; The glass raw material mixture is melted to obtain molten glass; The glass liquid is subjected to water quenching treatment to obtain glass particles; The glass particles are ground and classified to obtain the glass frit. The preparation method of glass frit according to claim 8, characterized in that the alkaline glass frit is prepared and formed according to the following steps: The raw materials of alkali metal oxides and the raw materials corresponding to the components of other alkaline glass frits are mixed to obtain the alkaline glass raw material mixture. The preparation method of glass frit according to claim 9, characterized in that the raw materials of the alkali metal oxide include Li ₂ CO ₃ , K ₂ CO ₃ , Na ₂ CO ₃ , and the alkaline glass frit is based on the oxide mole. The percentage meter contains the following components: 5~15% Li ₂ O; 1~10% Na ₂ O; 1~10% K ₂ O; 10~30% SiO ₂ ; 5~20% B ₂ O ₃ ; 5~20% ZnO; 0~10% Second alkaline earth metal oxide. The method for preparing glass frit according to claim 10, wherein the melting temperature of the alkaline glass frit is 800~1000°C. The method for preparing glass frit according to claim 10, wherein the raw material of the second alkaline earth metal oxide includes at least one of oxides, carbonates, nitrates and chlorides containing the second alkaline earth metal element. species, wherein the second alkaline earth metal element includes at least one of Mg, Ca, Sr, and Ba. The method for preparing glass frit according to any one of claims 8 to 12, wherein the grinding treatment method includes ball milling. The method for preparing glass frit according to any one of claims 8 to 12, characterized in that the classification treatment is carried out in an airflow mill. A conductive slurry, characterized in that it is used for N-type TOPCon crystalline silicon solar cells, including conductive metal powder and organic carrier, and also includes the glass frit of any one of claims 1-7 or any one of claims 8-14 The glass frit prepared by the method for preparing the glass frit described in the item. The conductive slurry of claim 15, wherein the conductive metal powder includes aluminum powder and silver powder, and the conductive slurry includes the following mass percentages of each component: 2~10wt % Glass frit; 7~13wt % organic carrier; 1~3wt% Aluminum powder; 80~90wt% Silver powder. The conductive paste according to claim 15, wherein the metallic silver powder includes micron-sized spherical, spherical-like and nano-sized silver powder. The conductive slurry according to claim 15, characterized in that the fineness of the conductive slurry is 3~5 μm, and the viscosity is 80~180 Pa·s under the measurement condition of 25°C. The conductive paste according to claim 17, wherein the particle size of the micron silver powder includes at least one of three levels of 1~2 μm, 2~4 μm and 4~6 μm. A method for preparing conductive slurry, characterized in that it includes the following steps: combining the glass frit prepared by the method of preparing the glass frit according to claim 1 or 2 or any one of claims 4 to 8, and organic The carrier, metal silver powder and metal aluminum powder are mixed to obtain the conductive paste.