Conductive silver paste and preparation method and application thereof

Abstract

The application relates to a conductive silver paste and a preparation method and application thereof. The conductive silver paste comprises silver powder, composite material and an organic carrier. The composite material is a co-sintered product of glass powder and ceramic powder. The conductive silver paste has low resistivity, high welding tension and cold and hot impact resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photovoltaics, in particular to a conductive silver paste and a preparation method and application thereof. BACKGROUND

[0002] The conductive silver paste for the front side of solar cells (front side silver paste) plays a crucial role in solar cell manufacturing. The front side silver paste is mainly used to make the conductive path on the front side of the solar cell, especially in the p-type silicon solar cell, it connects the metal grid between the cell pieces, forming the guidance and distribution of current. The conductive silver paste for the front side of solar cells mainly plays the role of making conductive path and improving photoelectric conversion efficiency, and also should have good weather resistance and oxidation resistance. The front side silver paste forms fine conductive paths, i.e. grid lines, on the front side of the solar cell. These grid lines are responsible for collecting and transmitting the current generated by the photovoltaic effect. The conductive performance directly affects the series resistance of the solar cell, and then affects the photoelectric conversion efficiency of the cell. In outdoor environments, solar cells need to withstand various weather conditions. The front side silver paste needs to have good weather resistance and oxidation resistance to ensure the stability and reliability of the cell during long-term use.

[0003] The existing conductive silver paste for the front side of solar cells is mainly composed of silver powder, glass powder, organic carrier and other components. Through long-term application, it is found that the existing conductive silver paste for the front side of solar cells has the problems of asynchronous high-temperature solidification of Ag and glass powder, rapid solidification of silver powder, and silver powder floating or sinking during screen printing, sintering and other processes, thereby affecting the photoelectric conversion efficiency. Moreover, the type and content of glass powder have important influence on the electrical properties and adhesion of the silver paste.

[0004] Therefore, the conductive silver paste for the front side of solar cells is one of the key materials indispensable in solar cell manufacturing. With the continuous development of solar cell technology and the continuous expansion of application fields, the adhesion and conductive performance of the front side silver paste will be continuously optimized and improved. SUMMARY

[0005] In view of the defects in the prior art, the purpose of the present application is to provide a conductive silver paste and a preparation method thereof. The conductive silver paste of the present application can improve the electrical performance, has a low resistivity, a high soldering tensile force and a cold-thermal shock resistance.

[0006] To achieve the above purpose, the first aspect of the present application provides a conductive silver paste, comprising silver powder, composite material and organic carrier, wherein the composite material is a co-sintered product of glass powder and ceramic powder.

[0007] On the basis of the above technical solutions, the weight ratio of the glass powder to the ceramic powder is 1:0.1-0.4. Preferably, the weight ratio of the glass powder to the ceramic powder is 1:0.2-0.3. For example but not limited to 1:0.2, 1:0.21, 1:0.22, 1:0.23, 1:0.24, 1:0.25, 1:0.26, 1:0.27, 1:0.28, 1:0.29, 1:0.3, etc.

[0008] On the basis of the above technical solutions, the preparation method of the co-sintered product comprises mixing the glass powder and the ceramic powder and sintering. In the present application, the silver powder and the like are compounded after co-sintering, which can significantly improve the bonding performance of the conductive silver paste and improve the mismatch problem of the silver powder and the glass bonding phase.

[0009] On the basis of the above technical solutions, the sintering conditions comprise a temperature of 700-850℃ and a time of 2-4h. In the present application, the sintering temperature can be but is not limited to 700℃, 710℃, 720℃, 730℃, 740℃, 750℃, 760℃, 770℃, 780℃, 790℃, 800℃, 810℃, 820℃, 830℃, 840℃, 850℃, etc. The sintering time can be but is not limited to 2h, 2.5h, 3h, 3.5h, 4h, etc.

[0010] On the basis of the above technical solutions, the glass powder contains SiO2 and PbO, and the weight ratio of SiO2 to PbO is 1:0.6-0.8. In the present application, PbO is contained, and the weight ratio of SiO2 to PbO is in the range of 1:0.6-0.8, and the electrical performance is more optimal.

[0011] On the basis of the above technical solutions, the glass powder further contains one or more of Al2O3, Na2O, K2O, MgO, CaO, MoO2 and SnO2.

[0012] On the basis of the above technical solutions, preferably, the content of SiO2 is 30-60% by weight, the content of PbO is 25-40% by weight, the content of Al2O3 is 0.1-3% by weight, the content of Na2O is 5-20% by weight, the content of K2O is 0.1-1% by weight, the content of MgO is 1-6% by weight, the content of CaO is 6-12% by weight, the content of MoO2 is 0-1% by weight, and the content of SnO2 is 0-1% by weight, based on the total weight of the glass powder.

[0013] On the basis of the above technical solutions, the ceramic powder contains fused quartz and zirconia.

[0014] On the basis of the above technical scheme, the weight ratio of fused quartz and zirconium oxide in the ceramic powder is 1:1-2. In the present application, the weight ratio of fused quartz and zirconium oxide can be, but is not limited to, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, etc.

[0015] On the basis of the above technical scheme, the content of silver powder is 80-95% by weight, the content of composite material is 1-5% by weight, and the content of organic carrier is 4-15% by weight based on the total weight of the conductive silver paste.

[0016] On the basis of the above technical scheme, the organic carrier comprises a solvent and an optional additive.

[0017] On the basis of the above technical scheme, the solvent is selected from one or more of diethylene glycol butyl ether acetate, dimethyl glutarate, dimethyl succinate and dimethyl adipate.

[0018] On the basis of the above technical scheme, the additive is selected from one or more of a dispersant, a leveling agent, a thixotropic agent, a coupling agent and a defoaming agent. In the present application, the dispersant, the leveling agent, the thixotropic agent, the coupling agent and the defoaming agent can be conventional options in the art, for example, the dispersant can be BYK-W980, etc.; the coupling agent can be a silane coupling agent, etc.; the leveling agent can be castor oil, etc.; and the defoaming agent can be dimethyl silicone oil, etc. In the present application, the additive can be added in an amount of 0.1-0.5 parts by weight based on the total weight of the conductive silver paste. For example, but not limited to, 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, etc.

[0019] On the basis of the above technical scheme, the conductive silver paste is a conductive silver paste for the front side of a solar cell. The front side silver paste is mainly used to collect and lead out photo-generated carriers, and the back side silver paste is mainly used for bonding (with lower requirement for conductivity), so the front side silver paste is the main one. The conductive silver paste of the present application is more suitable for the front side of a solar cell.

[0020] The second aspect of the present application provides a preparation method of the conductive silver paste, which comprises: mixing silver powder, composite material and organic carrier. The mixing can be, but is not limited to, rolling and dispersing uniformly in a three-roll mill.

[0021] The third aspect of the present application provides application of the conductive silver paste in the field of photovoltaics, especially as a conductive silver paste for the front side of a solar cell.

[0022] The present application has the following beneficial effects:

[0023] (1) The present application uses co-sintered glass powder and ceramic powder, which can improve the problem of poor combination due to too large difference in expansion coefficient between glass powder and silver powder, uses lead-containing glass powder in combination with fused quartz and zirconia ceramic, which can improve the density of conductive silver paste, and when the conductive silver paste formula of the present application is printed, the problem of unsynchronized high-temperature solidification of silver powder and glass powder, rapid solidification of silver powder, and upward or downward movement of silver powder can be overcome, thereby improving photoelectric conversion efficiency. Moreover, the use of co-sintered glass powder and ceramic powder can improve adhesion, and the prepared silver wire has a narrower line width and better effect.

[0024] (2) In the present application, the addition of PbO can promote the solidification of silver powder, improve the wettability of silver powder, and further improve the electrical properties and adhesion. DETAILED DESCRIPTION

[0025] In the following technical description, for the convenience of explanation, a plurality of details are provided to provide a full understanding of the disclosed embodiments. However, one or more embodiments can still be implemented without these details. In other cases, well-known structures and devices can be simplified to show.

[0026] The terms "first", "second", and the like in the specification and claims of the present disclosure are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the terms thus used can be interchanged under appropriate circumstances, so that the embodiments of the present disclosure described herein can be implemented. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion.

[0027] The following is an embodiment, in the following examples and comparative examples, the raw materials used are all obtained by commercial purchase.

[0028] Example 1

[0029] Step 1, preparation of glass powder:

[0030] 45 wt% of SiO2, 31.5 wt% of PbO, 1 wt% of Al2O3, 10 wt% of Na2O, 0.5 wt% of K2O, 3 wt% of MgO, 8 wt% of CaO, 0.5 wt% of MoO2, and 0.5 wt% of SnO2 were mixed to obtain the glass powder.

[0031] Step 2, preparation of ceramic powder:

[0032] 40 wt% of fused quartz and 60 wt% of zirconia were mixed to obtain the ceramic powder.

[0033] Step 3, preparation of co-sintered product of glass powder and ceramic powder

[0034] The glass powder obtained in step 1 and the ceramic powder obtained in step 2 are mixed in a weight ratio of 1:0.2, and sintered at 750°C for 2h, and after cooling, ground into particles to obtain a composite material.

[0035] Step 4, preparation of conductive silver paste:

[0036] 90wt% silver powder, 3wt% composite material, 6.6wt% diethylene glycol butyl ether acetate (organic carrier), 0.2wt% castor oil leveling agent and 0.2wt% dispersant BYK-W980 are mixed, ultrasonic dispersion and three-roll mill mixing are used, the paste is uniformly dispersed, and a conductive silver paste is obtained.

[0037] Example 2

[0038] Step 1, preparation of glass powder:

[0039] 32wt% SiO2, 26wt% PbO, 3wt% Al2O3, 20wt% Na2O, 0.1wt% K2O, 6wt% MgO, 11wt% CaO, 0.9wt% MoO2, 1wt% SnO2 are mixed to obtain a glass powder.

[0040] Step 2, preparation of ceramic powder:

[0041] 35wt% fused quartz and 65wt% zirconia are mixed to obtain a ceramic powder.

[0042] Step 3, preparation of co-sintered product of glass powder and ceramic powder

[0043] The glass powder obtained in step 1 and the ceramic powder obtained in step 2 are mixed in a weight ratio of 1:0.2, and sintered at 800°C for 3h, and after cooling, ground into particles to obtain a composite material.

[0044] Step 4, preparation of conductive silver paste:

[0045] 90wt% silver powder, 3wt% composite material, 6.6wt% diethylene glycol butyl ether acetate (organic carrier), 0.2wt% castor oil leveling agent and 0.2wt% dispersant BYK-W980 are mixed, ultrasonic dispersion and three-roll mill mixing are used, the paste is uniformly dispersed, and a conductive silver paste is obtained.

[0046] Example 3

[0047] Step 1, preparation of glass powder:

[0048] Mixing 45wt% of Si02, 31.5wt% of PbO, 1wt% of Al203, 10wt% of Na20, 0.5wt% of K20, 3wt% of MgO, 8wt% of CaO, 0.5wt% of Mo02, 0.5wt% of Sn02, a glass powder is obtained.

[0049] Step 2, preparing ceramic powder:

[0050] Mixing 50wt% of fused quartz, 50wt% of zirconia, a ceramic powder is obtained.

[0051] Step 3, preparing co-sintered product of glass powder and ceramic powder

[0052] Mixing the glass powder obtained in step 1 and the ceramic powder obtained in step 2 according to the weight ratio of 1:0.2, and sintering at 750℃ for 2h, grinding into particles after cooling, a composite material is obtained.

[0053] Step 4, preparing conductive silver paste:

[0054] Mixing 90wt% of silver powder, 3wt% of composite material, 6.6wt% of diethylene glycol butyl ether acetate (organic carrier), 0.2wt% of castor oil leveling agent and 0.2wt% of dispersant BYK-W980, ultrasonic dispersion and three-roll mill mixing are adopted, the paste is uniformly dispersed, and a conductive silver paste is obtained.

[0055] Example 4

[0056] Step 1, preparing glass powder:

[0057] Mixing 45wt% of Si02, 31.5wt% of PbO, 1wt% of Al203, 10wt% of Na20, 0.5wt% of K20, 3wt% of MgO, 8wt% of CaO, 0.5wt% of Mo02, 0.5wt% of Sn02, a glass powder is obtained.

[0058] Step 2, preparing ceramic powder:

[0059] Mixing 40wt% of fused quartz, 60wt% of zirconia, a ceramic powder is obtained.

[0060] Step 3, preparing co-sintered product of glass powder and ceramic powder

[0061] Mixing the glass powder obtained in step 1 and the ceramic powder obtained in step 2 according to the weight ratio of 1:0.3, and sintering at 750℃ for 2h, grinding into particles after cooling, a composite material is obtained.

[0062] Step 4, preparing conductive silver paste:

[0063] Mix 90 wt% silver powder, 3 wt% composite material, 6.6 wt% diethylene glycol butyl ether acetate (organic vehicle), 0.2 wt% castor oil leveling agent, and 0.2 wt% dispersant BYK-W980, disperse uniformly by ultrasonic dispersion and three-roll mill mixing, and obtain conductive silver paste.

[0064] Example 5

[0065] Step 1, preparation of glass powder:

[0066] Mix 45 wt% SiO2, 31.5 wt% PbO, 1 wt% Al2O3, 10 wt% Na2O, 0.5 wt% K2O, 3 wt% MgO, 8 wt% CaO, 0.5 wt% MoO2, and 0.5 wt% SnO2 to obtain glass powder.

[0067] Step 2, preparation of ceramic powder:

[0068] Mix 40 wt% fused quartz and 60 wt% zirconia to obtain ceramic powder.

[0069] Step 3, preparation of co-sintered product of glass powder and ceramic powder

[0070] Mix the glass powder obtained in step 1 and the ceramic powder obtained in step 2 in a weight ratio of 1:0.2, sinter at 750°C for 2h, and grind into particles after cooling to obtain a composite material.

[0071] Step 4, preparation of conductive silver paste:

[0072] Mix 90 wt% silver powder, 5 wt% composite material, 4.6 wt% diethylene glycol butyl ether acetate (organic vehicle), 0.2 wt% castor oil leveling agent, and 0.2 wt% dispersant BYK-W980, disperse uniformly by ultrasonic dispersion and three-roll mill mixing, and obtain conductive silver paste.

[0073] Example 6

[0074] Step 1, preparation of glass powder:

[0075] Mix 45 wt% SiO2, 31.5 wt% PbO, 1 wt% Al2O3, 10 wt% Na2O, 0.5 wt% K2O, 3 wt% MgO, 8 wt% CaO, 0.5 wt% MoO2, and 0.5 wt% SnO2 to obtain glass powder.

[0076] Step 2, preparation of ceramic powder:

[0077] Mix 40 wt% fused quartz and 60 wt% zirconia to obtain ceramic powder.

[0078] Step 3, preparing co-sintered product of glass powder and ceramic powder

[0079] The glass powder obtained in Step 1 and the ceramic powder obtained in Step 2 were mixed in a weight ratio of 1:0.1, and sintered at 750°C for 2h, and then ground into particles after cooling to obtain a composite material.

[0080] Step 4, preparing conductive silver paste:

[0081] 90wt% of silver powder, 3wt% of the composite material, 6.6wt% of diethylene glycol butyl ether acetate (organic carrier), 0.2wt% of castor oil leveling agent, and 0.2wt% of dispersant BYK-W980 were mixed, ultrasonic dispersion and three-roll mill mixing were used, and the paste was uniformly dispersed to obtain a conductive silver paste.

[0082] Example 7

[0083] Step 1, preparing glass powder:

[0084] 45wt% of SiO2, 31.5wt% of PbO, 1wt% of Al2O3, 10wt% of Na2O, 0.5wt% of K2O, 3wt% of MgO, 8wt% of CaO, 0.5wt% of MoO2, and 0.5wt% of SnO2 were mixed to obtain a glass powder.

[0085] Step 2, preparing ceramic powder:

[0086] 40wt% of fused quartz and 60wt% of zirconia were mixed to obtain a ceramic powder.

[0087] Step 3, preparing co-sintered product of glass powder and ceramic powder

[0088] The glass powder obtained in Step 1 and the ceramic powder obtained in Step 2 were mixed in a weight ratio of 1:0.4, and sintered at 750°C for 2h, and then ground into particles after cooling to obtain a composite material.

[0089] Step 4, preparing conductive silver paste:

[0090] 90wt% of silver powder, 3wt% of the composite material, 6.6wt% of diethylene glycol butyl ether acetate (organic carrier), 0.2wt% of castor oil leveling agent, and 0.2wt% of dispersant BYK-W980 were mixed, ultrasonic dispersion and three-roll mill mixing were used, and the paste was uniformly dispersed to obtain a conductive silver paste.

[0091] Example 8

[0092] Step 1, preparing glass powder:

[0093] Mixing 45wt% of SiO2, 31.5wt% of PbO, 1wt% of Al2O3, 10wt% of Na2O, 0.5wt% of K2O, 3wt% of MgO, 8wt% of CaO, 0.5wt% of MoO2, 0.5wt% of SnO2 to obtain a glass powder.

[0094] Step 2, preparing ceramic powder:

[0095] Mixing 40wt% of fused quartz and 60wt% of zirconia to obtain a ceramic powder.

[0096] Step 3, preparing co-sintered product of glass powder and ceramic powder

[0097] Mixing the glass powder obtained in Step 1 and the ceramic powder obtained in Step 2 according to a weight ratio of 1:0.8, and sintering at 750°C for 2h, and grinding into particles after cooling to obtain a composite material.

[0098] Step 4, preparing conductive silver paste:

[0099] Mixing 90wt% of silver powder, 3wt% of the composite material, 6.6wt% of diethylene glycol butyl ether acetate (organic carrier), 0.2wt% of castor oil leveling agent and 0.2wt% of dispersant BYK-W980, and uniformly dispersing the paste by ultrasonic dispersion and three-roll mill mixing to obtain a conductive silver paste.

[0100] Example 9

[0101] According to the method of Example 1, except that PbO in the glass powder is replaced by SiO2, i.e.:

[0102] Step 1, preparing glass powder:

[0103] Mixing 76.5wt% of SiO2, 1wt% of Al2O3, 10wt% of Na2O, 0.5wt% of K2O, 3wt% of MgO, 8wt% of CaO, 0.5wt% of MoO2, 0.5wt% of SnO2 to obtain a glass powder.

[0104] Step 2, preparing ceramic powder:

[0105] Mixing 40wt% of fused quartz and 60wt% of zirconia to obtain a ceramic powder.

[0106] Step 3, preparing co-sintered product of glass powder and ceramic powder

[0107] Mixing the glass powder obtained in Step 1 and the ceramic powder obtained in Step 2 according to a weight ratio of 1:0.2, and sintering at 750°C for 2h, and grinding into particles after cooling to obtain a composite material.

[0108] Step 4, preparation of conductive silver paste:

[0109] Mix 90wt% silver powder, 3wt% composite material, 6.6wt% diethylene glycol butyl ether acetate (organic carrier), 0.2wt% castor oil leveling agent and 0.2wt% dispersant BYK-W980, disperse by ultrasonic and mix by three-roll mill, disperse the paste uniformly, get conductive silver paste

[0110] Comparative Example 1

[0111] According to the method of Example 1, except that ceramic powder is not used, i.e.:

[0112] Step 1, preparation of glass powder:

[0113] Mix 45wt% SiO2, 31.5wt% PbO, 1wt% Al2O3, 10wt% Na2O, 0.5wt% K2O, 3wt% MgO, 8wt% CaO, 0.5wt% MoO2, 0.5wt% SnO2, get glass powder.

[0114] Step 2, preparation of conductive silver paste:

[0115] Mix 90wt% silver powder, 3wt% glass powder, 6.6wt% diethylene glycol butyl ether acetate (organic carrier), 0.2wt% castor oil leveling agent and 0.2wt% dispersant BYK-W980, disperse by ultrasonic and mix by three-roll mill, disperse the paste uniformly, get conductive silver paste.

[0116] Comparative Example 2

[0117] According to the method of Example 1, except that fused quartz is replaced by zirconia, i.e.:

[0118] Step 1, preparation of glass powder:

[0119] Mix 45wt% SiO2, 31.5wt% PbO, 1wt% Al2O3, 10wt% Na2O, 0.5wt% K2O, 3wt% MgO, 8wt% CaO, 0.5wt% MoO2, 0.5wt% SnO2, get glass powder.

[0120] Step 2, preparation of co-sintering product of glass powder and ceramic powder

[0121] Mix the glass powder obtained in Step 1 with zirconia according to the weight ratio of 1:0.2, and sinter at 750℃ for 2h, grind into particles after cooling, get composite material.

[0122] Step 3, preparation of conductive silver paste:

[0123] 90wt% silver powder, 3wt% composite material, 6.6wt% diethylene glycol butyl ether acetate (organic carrier), 0.2wt% castor oil leveling agent and 0.2wt% dispersant BYK-W980 were mixed, ultrasonic dispersion and three-roll mill mixing were used to disperse the slurry uniformly, and conductive silver paste was obtained.

[0124] Comparative Example 3

[0125] According to the method of Example 1, except that zirconium oxide is replaced by, i.e.:

[0126] Step 1, preparation of glass powder:

[0127] 45wt% SiO2, 31.5wt% PbO, 1wt% Al2O3, 10wt% Na2O, 0.5wt% K2O, 3wt% MgO, 8wt% CaO, 0.5wt% MoO2, and 0.5wt% SnO2 were mixed to obtain glass powder.

[0128] Step 2, preparation of co-sintered product of glass powder and ceramic powder

[0129] The glass powder obtained in step 1 and fused quartz were mixed in a weight ratio of 1:0.2, sintered at 750°C for 2h, and ground into particles after cooling to obtain a composite material.

[0130] Step 3, preparation of conductive silver paste:

[0131] 90wt% silver powder, 3wt% composite material, 6.6wt% diethylene glycol butyl ether acetate (organic carrier), 0.2wt% castor oil leveling agent and 0.2wt% dispersant BYK-W980 were mixed, ultrasonic dispersion and three-roll mill mixing were used to disperse the slurry uniformly, and conductive silver paste was obtained.

[0132] Comparative Example 4

[0133] According to the method of Example 1, except that the glass powder and ceramic powder are not co-sintered, i.e.:

[0134] Step 1, preparation of glass powder:

[0135] 45wt% SiO2, 31.5wt% PbO, 1wt% Al2O3, 10wt% Na2O, 0.5wt% K2O, 3wt% MgO, 8wt% CaO, 0.5wt% MoO2, and 0.5wt% SnO2 were mixed to obtain glass powder.

[0136] Step 2, preparation of ceramic powder:

[0137] Mixing 40 wt% of fused quartz, 60 wt% of zirconia to obtain ceramic powder.

[0138] Step 3, preparing co-sintered product of glass powder and ceramic powder

[0139] Mixing the glass powder obtained in step 1 and the ceramic powder obtained in step 2 according to a weight ratio of 1:0.2 to obtain a composite material.

[0140] Step 4, preparing conductive silver paste:

[0141] Mixing 90 wt% of silver powder, 3 wt% of composite material, 6.6 wt% of diethylene glycol butyl ether acetate (organic carrier), 0.2 wt% of castor oil leveling agent and 0.2 wt% of dispersant BYK-W980, using ultrasonic dispersion and three-roll mill mixing, the paste is uniformly dispersed, to obtain conductive silver paste.

[0142] Test example

[0143] Performance test: the resistivity, contact resistivity, peel strength and aging performance of the electrodes prepared by the conductive silver paste of the examples and the comparative examples were tested respectively, and the results are shown in Table 1.

[0144] (1) Test method of resistivity: screen printing and coating the conductive paste of the examples and the comparative examples on N-type TOPCon solar blue film sheet respectively, vacuum drying at room temperature for 3 hours. Then using circulating hot air to cure at a temperature of 200°C, the curing time is 30 minutes, to obtain fine wire electrode. Then use AEMC 6240 microresistometer to measure the resistance of the fine wire electrode, and WI-5000 interferometric coaxial three-dimensional microscope to measure the width and length of the fine wire. The pattern specification of the above formed fine wire electrode is that the width of the middle line segment is 40 μm, the length is 9 cm, and the contact pads of the head and tail are 2 mm x 2 mm. The line resistance between the contact pads is measured by four-terminal sensing, and the measured resistance is standardized by the grid line length, and multiplied by the cross-sectional area (measured using an alpha step profiler) to obtain the resistivity (p) of the grid line. Each resistivity data set is obtained by averaging the values measured on four different grid lines.

[0145] (2) Test method of contact resistivity: screen printing and coating the conductive paste of the examples and the comparative examples on N-type TOPCon solar blue film sheet respectively, vacuum drying at room temperature for 3 hours. Then using circulating hot air to cure at a temperature of 200°C, the curing time is 50 minutes, to obtain fine wire electrode. The electrode pattern consists of 5 linear electrodes with a line width of 0.5 mm and a length of 50 mm, with a line spacing of 3 mm. Then, using AEMC 6240 microresistometer to measure the resistance between the linear electrodes with different spacing, the distance is calculated by transmission line model method (TLM) to obtain the contact resistivity (Rc) with the substrate.c ).

[0146] (3) Test method of peel strength: The conductive paste of the examples and the comparative examples was screen printed and coated on N-type TOPCon solar blue film pieces, and vacuum dried at room temperature for 3 hours. Then, using circulating hot air, curing was performed at a temperature of 200°C for 50 minutes to obtain fine line electrodes. To obtain electrode patterns. The pattern specification of the test electrode was 5 cm long and 2 mm wide, and then a tin-plated copper tape with a width of 1 mm was welded to the test electrode. The substrate was fixed on the tensile meter platform to test the peel strength. The type of tension meter was NLB - 100 electronic push-pull pressure meter. The test condition was to peel off the solder tape at an angle of 180° at a speed of 60 mm / min, and the tensile value was obtained, which was recorded every 1 second. The obtained tension was the average value of the 5 cm long electrode.

[0147] (4) Test method of aging resistance: After 200 cold and hot cycles, the decay of photoelectric conversion efficiency was tested, and the aging resistance (decay %) = (initial photoelectric conversion efficiency - photoelectric conversion efficiency after 200 cold and hot cycles) ÷ initial photoelectric conversion efficiency × 100%.

[0148] Table 1

[0149]

[0150] As can be seen from the above table, the conductive silver paste for solar cells prepared by using the formula of the present application can reduce the resistivity and contact resistance, and improve the welding tension and aging resistance.

[0151] The present application is not limited to the embodiments already described above and can be modified and changed in various ways without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

[0152] In the present application, each embodiment can focus on the differences from other embodiments, and the same or similar parts between various embodiments can be referred to each other.

Claims

1. An electrically conductive silver paste comprising silver powder, a complexing agent and an organic vehicle, wherein, The composite is a co-sintered product of the glass powder and the ceramic powder, and the weight ratio of the glass powder to the ceramic powder is 1:0.1-0.4; The glass powder contains SiO2 and PbO, and the weight ratio of SiO2 to PbO is 1:0.6-0.8; The ceramic powder contains fused quartz and zirconia, and the weight ratio of the fused quartz to the zirconia in the ceramic powder is 1:1-2; The content of the silver powder is 80-95% by weight, the content of the composite is 1-5% by weight, and the content of the organic vehicle is 4-15% by weight, based on the total weight of the conductive silver paste.

2. The conductive silver paste according to claim 1, characterized in that, The preparation method of the co-sintered product comprises mixing the glass powder and the ceramic powder and sintering.

3. The conductive silver paste according to claim 2, characterized in that, The sintering conditions comprise a temperature of 700-850℃ and a time of 2-4h.

4. The conductive silver paste of claim 1, wherein, The glass powder further contains one or more of Al2O3, Na2O, K2O, MgO, CaO, MoO2 and SnO2.

5. The conductive silver paste according to claim 4, characterized in that, The content of SiO2 is 30-60% by weight, the content of PbO is 25-40% by weight, the content of Al2O3 is 0.1-3% by weight, the content of Na2O is 5-20% by weight, the content of K2O is 0.1-1% by weight, the content of MgO is 1-6% by weight, the content of CaO is 6-12% by weight, the content of MoO2 is 0-1% by weight, and the content of SnO2 is 0-1% by weight, based on the total weight of the glass powder.

6. The conductive silver paste of claim 1, wherein, The organic vehicle comprises a solvent and optional additives.

7. The electrically conductive silver paste of claim 6, wherein, The solvent is selected from one or more of diethylene glycol butyl ether acetate, dimethyl glutarate, dimethyl succinate and dimethyl adipate.

8. The conductive silver paste of claim 6, wherein, The additives are selected from one or more of a dispersant, a leveling agent, a thixotropic agent, a coupling agent and an antifoaming agent.

9. The conductive silver paste according to any one of claims 1 to 8, characterized in that, The conductive silver paste is a conductive silver paste for the front side of a solar cell.

10. A method of preparing the electrically conductive silver paste of any one of claims 1-9, comprising: The silver powder, the composite and the organic vehicle are mixed.

11. Use of the conductive silver paste according to any one of claims 1-9 in the field of photovoltaics.

12. Use according to claim 11, characterized in that, The conductive silver paste is a conductive silver paste for the front side of a solar cell. The silver powder, the composite and the organic vehicle are mixed.

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