Frit and its preparation method and application, silver-aluminum paste and its preparation method and application

Abstract

The present invention belongs to the technical field of crystalline silicon solar cells, and particularly relates to a frit and its preparation method and application, a silver-aluminum paste and its preparation method and application. The present invention provides a frit, which comprises the following components in parts by mass: 3-10 parts of silicon dioxide, 30-70 parts of lead oxide, 20-50 parts of tellurium dioxide, 1-10 parts of zinc oxide, 0.5-5 parts of aluminum oxide, 0.5-5 parts of alkaline earth metal oxide, 0.5-5 parts of a regulator, and 0-10 parts of boric acid; the regulator comprises indium hydroxide and / or indium tungstate. The silver-aluminum paste prepared from the frit provided by the present invention can effectively reduce the contact resistance between the metal electrode and the P-Si emitter, thereby improving the conversion efficiency of the N-type crystalline silicon solar cell.

Description

Technical Field

[0001] The present invention belongs to the technical field of crystalline silicon solar cells, and particularly relates to a frit and its preparation method and application, a silver-aluminum paste and its preparation method and application. Background Art

[0002] Crystalline silicon solar cells can be divided into P-type crystalline silicon solar cells and N-type crystalline silicon solar cells according to the type of the central crystalline silicon substrate. N-type crystalline silicon solar cells have the advantages of long minority carrier lifetime, no light-induced degradation, high long-term power generation yield, low temperature coefficient, and high power output under high temperature conditions. Compared with P-type crystalline silicon solar cells, they have higher conversion efficiency.

[0003] However, with the continuous improvement of the conversion efficiency of N-type crystalline silicon solar cells, the short-circuit current is getting larger and larger, and the influence of the electrode resistance on the battery conversion efficiency is also becoming more and more significant. At present, the contact resistance between the metal electrode and the P-Si emitter in N-type crystalline silicon solar cells is relatively large, resulting in the defect of relatively low conversion rate in N-type crystalline silicon solar cells. Summary of the Invention

[0004] The present invention provides a frit and its preparation method and application, a silver-aluminum paste and its preparation method and application. The silver-aluminum paste prepared from the frit provided by the present invention can effectively reduce the contact resistance between the metal electrode and the P-Si emitter, thereby improving the conversion efficiency of N-type crystalline silicon solar cells.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a frit, comprising the following components in parts by mass: 3-10 parts of silicon dioxide, 30-70 parts of lead oxide, 20-50 parts of tellurium dioxide, 1-10 parts of zinc oxide, 0.5-5 parts of aluminum oxide, 0.5-5 parts of alkaline earth metal oxide, 0.5-5 parts of regulator, and 0-10 parts of boric acid;

[0007] The regulator includes indium hydroxide and / or indium tungstate.

[0008] Preferably, the alkaline earth metal oxide includes one or more of barium oxide, magnesium oxide, and calcium oxide.

[0009] Preferably, when the regulator includes indium hydroxide and indium tungstate, the mass ratio of indium hydroxide to indium tungstate is 1-2:1-2.

[0010] The present invention also provides a preparation method of the frit according to the above technical solution, comprising the following steps:

[0011] Mix the components included in the frit, and successively perform melting and quenching treatments to obtain the frit.

[0012] Preferably, the temperature of the melting is 1000 - 1200 °C, and the time is 0.5 - 1 h.

[0013] The present invention also provides an application of the frit described in the above technical solution or the frit prepared by the preparation method described in the above technical solution in a silver-aluminum paste.

[0014] The present invention also provides a silver-aluminum paste, which includes the following components in parts by mass: 70 - 85 parts of silver powder, 5 - 10 parts of aluminum powder, 5 - 10 parts of frit, and 5 - 10 parts of an organic carrier;

[0015] The frit is the frit described in the above technical solution or the frit prepared by the preparation method described in the above technical solution.

[0016] Preferably, in parts by mass, the organic carrier includes the following components:

[0017] 85 - 95 parts of a solvent, 1 - 3 parts of a thickener, 3 - 8 parts of a thixotropic agent, and 1 - 2 parts of a dispersant.

[0018] The present invention also provides a preparation method of the silver-aluminum paste described in the above technical solution, which includes the following steps:

[0019] Mix the silver powder, aluminum powder, frit, and organic carrier to obtain the silver-aluminum paste.

[0020] The present invention also provides an application of the silver-aluminum paste described in the above technical solution or the silver-aluminum paste prepared by the preparation method described in the above technical solution in an N-type crystalline silicon solar cell.

[0021] The present invention provides a glass frit, comprising the following components in parts by mass: 3-10 parts of silicon dioxide, 30-70 parts of lead oxide, 20-50 parts of tellurium dioxide, 1-10 parts of zinc oxide, 0.5-5 parts of aluminum oxide, 0.5-5 parts of alkaline earth metal oxide, 0.5-5 parts of a regulator, and 0-10 parts of boric acid; the regulator comprises indium hydroxide and / or indium tungstate. The glass frit provided by the present invention is applied to the silver-aluminum paste of an N-type crystalline silicon solar cell. After the metallization process, silicon dioxide and lead oxide in the glass frit can form a vitreous structure; among them, lead oxide has strong corrosiveness to the antireflection film of the N-type solar cell, enabling the paste to penetrate the antireflection film and directly connect with the silicon wafer, improving the contact performance between the silver-aluminum paste and the P-Si emitter; the regulator in the glass frit can perform p+ doping on the P-Si emitter during the metallization process, increasing the doping concentration of the P-Si emitter to reduce the Schottky barrier width or height at the contact interface between the metal electrode and the P-Si emitter. Under the synergistic effect of each component of the glass frit in the present invention, the silver-aluminum paste has excellent contact performance and good electrical conductivity with the P-Si emitter of the N-type crystalline silicon solar cell, thereby improving the conversion efficiency of the N-type crystalline silicon solar cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the line transmission model adopted by the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0023] The present invention provides a glass frit, comprising the following components in parts by mass: 3-10 parts of silicon dioxide, 30-70 parts of lead oxide, 20-50 parts of tellurium dioxide, 1-10 parts of zinc oxide, 0.5-5 parts of aluminum oxide, 0.5-5 parts of alkaline earth metal oxide, 0.5-5 parts of a regulator, and 0-10 parts of boric acid;

[0024] The regulator comprises indium hydroxide and / or indium tungstate.

[0025] In the present invention, unless otherwise specified, the raw materials used can be commercially available products well-known to those skilled in the art.

[0026] Based on parts by mass, the glass frit provided by the present invention comprises 3-10 parts of silicon dioxide, more preferably 4-9 parts, and even more preferably 5-8 parts. In the present invention, the silicon dioxide can form a vitreous body during the subsequent metallization process, improving the adhesion of the metal electrode on the surface of the crystalline silicon.

[0027] Based on the parts by mass of the silica, the frit provided by the present invention comprises 30 to 70 parts of lead oxide, further preferably 35 to 65 parts, and more preferably 40 to 60 parts. In the present invention, on the one hand, the lead oxide can form a vitreous body, and at the same time has strong corrosiveness to the antireflection film of the N-type solar cell, enabling the paste to penetrate the antireflection film and be directly connected to the silicon wafer, thereby improving the contact performance between the silver-aluminum paste and the P-Si emitter.

[0028] Based on the parts by mass of the silica, the frit provided by the present invention comprises 20 to 50 parts of tellurium dioxide, further preferably 25 to 45 parts, and more preferably 30 to 40 parts. In the present invention, the tellurium dioxide can improve the adhesion of the metal electrode prepared from the silver-aluminum paste on the battery chip.

[0029] Based on the parts by mass of the silica, the frit provided by the present invention comprises 1 to 10 parts of zinc oxide, further preferably 2 to 9 parts, and more preferably 3 to 8 parts. In the present invention, the zinc oxide can improve the thermal stability of the glass powder during the sintering process.

[0030] Based on the parts by mass of the silica, the frit provided by the present invention comprises 0.5 to 5 parts of alumina, further preferably 1 to 4 parts, and more preferably 2 to 3 parts. In the present invention, the alumina can improve the thermal expansion coefficient of the glass powder during the sintering process.

[0031] Based on the parts by mass of the silica, the frit provided by the present invention comprises 0.5 to 5 parts of alkaline earth metal oxide, further preferably 1 to 4 parts, and more preferably 1.5 to 3.5 parts. In the present invention, the alkaline earth metal oxide preferably comprises one or more of barium oxide, magnesium oxide and calcium oxide. In the present invention, when the alkaline earth metal oxide preferably comprises any two of barium oxide, magnesium oxide and calcium oxide, the mass ratio of any two alkaline earth metal oxides is 1:1; when the alkaline earth metal oxide comprises barium oxide, magnesium oxide and calcium oxide, the mass ratio of barium oxide, magnesium oxide and calcium oxide is preferably 1:1:1. In the present invention, the alkaline earth metal oxide can improve the electrical conductivity of the glass powder.

[0032] Based on the parts by mass of the silica, the frit provided by the present invention comprises 0.5 to 5 parts, further preferably 1 to 4.5 parts, and more preferably 1.5 to 4 parts of a regulator. In the present invention, the regulator comprises indium hydroxide and / or indium tungstate. In the present invention, when the regulator comprises indium hydroxide and indium tungstate, the mass ratio of indium hydroxide to indium tungstate is preferably 1 to 2:1 to 2. In the present invention, indium ions in the indium hydroxide and / or indium tungstate can enter the P-Si emitter of the N-type solar cell during the paste metallization process for p+ doping (heavy doping). Due to the increase in the doping concentration of the P-Si emitter, the Schottky barrier width at the contact interface between the metal electrode and the P-Si emitter can be reduced; indium tungstate can improve the work function of the metal electrode during the paste metallization process, thereby reducing the Schottky barrier height at the contact interface between the metal electrode and the P-Si emitter.

[0033] Based on the parts by mass of the silica, the frit provided by the present invention comprises 0 to 10 parts, further preferably 1 to 9 parts, and more preferably 2 to 8 parts of boric acid. In the present invention, the boric acid can perform p+ doping on the P-Si emitter, further increasing the doping concentration of the P-Si emitter to reduce the Schottky barrier width at the contact interface between the metal electrode and the P-Si emitter.

[0034] The frit provided by the present invention has a low softening temperature and thermal expansion coefficient, low resistivity and dielectric loss, and a wide sintering temperature range (780 - 850 °C).

[0035] The present invention also provides a method for preparing the frit according to the above technical solution, comprising the following steps:

[0036] Mix the components comprised in the frit, and successively perform melting and quenching treatments to obtain the frit.

[0037] In the present invention, the mixing is preferably carried out under stirring conditions. In the present invention, the stirring time is preferably 4 h. In the present invention, the mixing is preferably carried out in a mixer.

[0038] Before the melting, the present invention also preferably includes preheating the obtained mixture. In the present invention, the preheating temperature is preferably 500 °C; the heating rate to the preheating temperature is preferably 10 °C / min; the holding time is preferably 0.5 h. In the present invention, the preheating is preferably carried out in a high-temperature sintering furnace. In the present invention, the preheating can expel the gases in the mixture.

[0039] In the present invention, the temperature of the melting is preferably 1000 - 1200 °C, more preferably 1050 - 1180 °C, and even more preferably 1100 - 1150 °C; the heating rate to the melting temperature is preferably 10 °C / min; the holding time is preferably 0.5 - 1 h, more preferably 0.6 - 0.9 h, and even more preferably 0.7 - 0.8 h. In the present invention, the melting is preferably carried out in a high-temperature sintering furnace.

[0040] The present invention has no special limitation on the process of the quenching treatment, and the molten material liquid can be directly poured into deionized water rapidly. After the quenching treatment, the present invention preferably further includes drying, grinding and sieving the obtained material.

[0041] In the present invention, the temperature of the drying is preferably 100 °C and the time is preferably 4 h. In the present invention, the drying is preferably carried out in an oven.

[0042] In the present invention, the grinding preferably includes dry grinding and wet grinding in sequence.

[0043] In the present invention, the grinding is preferably carried out in a ball milling tank; the grinding balls used in the grinding process are preferably zirconia grinding balls. In the present invention, the volume ratio of the material to the grinding balls in the dry grinding process is preferably 1:1, and the volume ratio of the total volume of the material and the grinding balls to the volume of the ball milling tank is preferably 2:3. In the present invention, the rotation speed of the dry grinding is preferably 500 rpm and the time is preferably 4 h. The present invention has no special limitation on the process of the dry grinding, and the process well-known to those skilled in the art can be adopted.

[0044] In the present invention, the wet grinding is preferably carried out in an ethanol system. In the present invention, the volume ratio of the material, the grinding balls and ethanol in the wet grinding process is preferably 1:1:1. In the present invention, the rotation speed of the wet grinding is preferably 400 rpm and the time is preferably 8 h. The present invention has no special limitation on the process of the wet grinding, and the process well-known to those skilled in the art can be adopted.

[0045] After the wet grinding, the present invention preferably further includes drying the obtained material; the temperature of the drying is preferably 60 °C and the time is preferably 48 h. In the present invention, the drying is preferably carried out in an oven.

[0046] In the present invention, the particle size of the material obtained after the grinding is preferably 2 - 3 μm.

[0047] In the present invention, the aperture of the sieve mesh used in the sieving treatment is preferably 500 meshes. The present invention has no special limitation on the process of the sieving treatment, and the process well-known to those skilled in the art can be adopted. In the present invention, the particle size of the glass frit is preferably 2 μm.

[0048] The preparation method of the glass frit provided by the present invention is simple and low in cost, and is suitable for industrial production.

[0049] The present invention also provides the application of the glass frit described in the above technical solution or the glass frit prepared by the preparation method described in the above technical solution in silver-aluminum paste.

[0050] The present invention also provides a silver-aluminum paste, which comprises the following components in parts by mass: 70-85 parts of silver powder, 5-10 parts of aluminum powder, 5-10 parts of glass frit and 5-10 parts of organic carrier;

[0051] The glass frit is the glass frit described in the above technical solution or the glass frit prepared by the preparation method described in the above technical solution.

[0052] In parts by mass, the silver-aluminum paste provided by the present invention comprises 70-85 parts of silver powder, more preferably 72-83 parts, and even more preferably 75-80 parts. In the present invention, the particle size of the silver powder is preferably 1 μm.

[0053] In parts by mass based on the silver powder, the silver-aluminum paste provided by the present invention comprises 5-10 parts of aluminum powder, more preferably 6-9 parts, and even more preferably 7-8 parts. In the present invention, the particle size of the aluminum powder is preferably 1 μm. In the present invention, the aluminum powder can reduce the contact resistance between the metal electrode and the P-Si emitter.

[0054] In parts by mass based on the silver powder, the silver-aluminum paste provided by the present invention comprises 5-10 parts of glass frit, more preferably 6-9 parts, and even more preferably 7-8 parts.

[0055] In parts by mass based on the silver powder, the silver-aluminum paste provided by the present invention comprises 5-10 parts of organic carrier, more preferably 6-9 parts, and even more preferably 7-8 parts. In parts by mass, the organic carrier provided by the present invention comprises the following components: 85-95 parts of solvent, 1-3 parts of thickener, 3-8 parts of thixotropic agent and 1-2 parts of dispersant. In a specific embodiment of the present invention, in parts by mass, the organic carrier comprises the following components: 90 parts of solvent, 3 parts of thickener, 5 parts of thixotropic agent and 2 parts of dispersant.

[0056] In the present invention, the solvent preferably comprises one or more of butyl carbitol, butyl carbitol acetate, tributyl citrate and dodecyl ester. In the present invention, the thickener preferably comprises one or more of ethyl cellulose, polyamide, polyamide modified resin and hydrogen-bond-containing rosin resin. In the present invention, the thixotropic agent preferably comprises one or more of polyamide wax, hydrogenated castor oil, modified polyamide wax and modified hydrogenated castor oil. In the present invention, the dispersant preferably comprises one or more of tributyl phosphate, ammonium citrate and polyacrylic acid.

[0057] The present invention also provides a method for preparing the silver-aluminum paste described in the above technical solution, comprising the following steps:

[0058] Mix silver powder, aluminum powder, glass frit and organic carrier to obtain the silver-aluminum paste.

[0059] In the present invention, the particle size of the solid substances in the silver-aluminum paste is preferably less than 10 μm. In the present invention, the mixing is preferably carried out in a three-roll mill. The present invention has no special limitation on the mixing process, as long as the silver-aluminum paste with the desired particle size can be obtained.

[0060] The present invention also provides the application of the silver-aluminum paste described in the above technical solution or the silver-aluminum paste prepared by the preparation method described in the above technical solution on an N-type crystalline silicon solar cell. The present invention has no special limitation on the specific implementation manner of the application, and it can be carried out in a manner well-known to those skilled in the art.

[0061] In order to further illustrate the present invention, the following will describe in detail a glass frit and its preparation method and application, a silver-aluminum paste and its preparation method and application provided by the present invention with reference to the accompanying drawings and embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0062] Example 1

[0063] Prepare materials according to the following mass parts: 60 parts of lead oxide, 31 parts of tellurium dioxide, 5 parts of silicon dioxide, 1.5 parts of zinc oxide, 0.5 part of aluminum oxide, 0.5 part of barium oxide, 0.5 part of magnesium oxide, 0.5 part of indium hydroxide;

[0064] The preparation of the glass frit includes the following steps:

[0065] Put the above raw materials into a mixer and mix for 4 h to obtain a mixture;

[0066] Put the mixture into a corundum crucible, and then place the corundum crucible in a high-temperature sintering furnace. Heat from room temperature to 500 °C at a heating rate of 10 °C / min and hold for 0.5 h for preheating to remove the gas in the mixture; heat to 1000 °C at a heating rate of 10 °C / min and hold for 1 h for melting, and quickly pour the obtained glass liquid into deionized water for quenching treatment to obtain glass frit;

[0067] Put the glass frit into an oven and dry it at 100 °C for 4 h. Then put it into a ball mill and dry mill it at a rotation speed of 500 rpm for 4 h (where the volume ratio of the glass frit to the zirconia grinding balls is 1:1, and the volume of the glass frit and the zirconia grinding balls accounts for 2 / 3 of the total volume of the ball mill tank); wet mill it at a rotation speed of 400 rpm for 8 h (where the volume ratio of the glass frit, the zirconia grinding balls and ethanol is 1:1:1); then dry it at 60 °C for 48 h and screen it with a 500-mesh standard sieve to obtain glass material with a particle size of about 2 μm.

[0068] Example 2

[0069] Prepare the materials according to the following mass parts: 60 parts of lead oxide, 31 parts of tellurium dioxide, 3 parts of silicon dioxide, 1.5 parts of zinc oxide, 0.5 part of aluminum oxide, 2 parts of boric acid, 0.5 part of barium oxide, 0.5 part of calcium oxide, 0.5 part of indium hydroxide, 0.5 part of indium tungstate;

[0070] The preparation of the glass material includes the following steps:

[0071] Put the above raw materials into a mixer and mix for 4 h to obtain a mixed material;

[0072] Put the mixed material into a corundum crucible, and then place the corundum crucible in a high-temperature sintering furnace. Heat it from room temperature to 500 °C at a heating rate of 10 °C / min and keep it warm for 0.5 h for preheating to remove the gas in the mixed material; heat it to 1000 °C at a heating rate of 10 °C / min and keep it warm for 1 h for melting. Pour the obtained glass liquid quickly into deionized water for quenching treatment to obtain glass frit;

[0073] Put the glass frit into an oven and dry it at 100 °C for 4 h. Then put it into a ball mill and dry mill it at a rotation speed of 500 rpm for 4 h (where the volume ratio of the glass frit to the zirconia grinding balls is 1:1, and the volume of the glass frit and the zirconia grinding balls accounts for 2 / 3 of the total volume of the ball mill tank); wet mill it at a rotation speed of 400 rpm for 8 h (where the volume ratio of the glass frit, the zirconia grinding balls and ethanol is 1:1:1); then dry it at 60 °C for 48 h and screen it with a 500-mesh standard sieve to obtain glass material with a particle size of about 2 μm.

[0074] Example 3

[0075] Prepare the materials according to the following mass parts: 65 parts of lead oxide, 26 parts of tellurium dioxide, 5 parts of silicon dioxide, 2 parts of zinc oxide, 0.5 part of aluminum oxide, 0.5 part of calcium oxide, 0.5 part of indium tungstate, 0.5 part of indium hydroxide;

[0076] The preparation of the glass material includes the following steps:

[0077] Put the above raw materials into a mixer and mix for 4 h to obtain a mixed material;

[0078] Load the mixture into a corundum crucible, and then place the corundum crucible in a high-temperature sintering furnace. Heat it from room temperature to 500 °C at a heating rate of 10 °C / min and hold for 0.5 h for preheating to remove the gas in the mixture; heat it to 1100 °C at a heating rate of 10 °C / min and hold for 1 h for melting. Pour the obtained glass liquid quickly into deionized water for quenching treatment to obtain glass frit.

[0079] Put the glass frit into an oven and dry it at 100 °C for 4 h, then put it into a ball mill and dry mill it at a rotation speed of 500 rpm for 4 h (where the volume ratio of the glass frit to the zirconia grinding balls is 1:1, and the volume of the glass frit and the zirconia grinding balls accounts for 2 / 3 of the total volume of the ball mill tank); wet mill it at a rotation speed of 400 rpm for 8 h (where the volume ratio of the glass frit, the zirconia grinding balls and ethanol is 1:1:1); then dry it at 60 °C for 48 h and screen it with a 500-mesh standard sieve to obtain glass powder with a particle size of about 2 μm.

[0080] Example 4

[0081] Prepare the materials according to the following mass parts: 65 parts of lead oxide, 26 parts of tellurium dioxide, 3 parts of silicon dioxide, 1.5 parts of zinc oxide, 0.5 part of aluminum oxide, 0.5 part of calcium oxide, 0.5 part of magnesium oxide, 2 parts of boric acid, 1 part of indium hydrotungstate;

[0082] The preparation of the glass powder includes the following steps:

[0083] Put the above raw materials into a mixer and mix for 4 h to obtain a mixture;

[0084] Load the mixture into a corundum crucible, and then place the corundum crucible in a high-temperature sintering furnace. Heat it from room temperature to 500 °C at a heating rate of 10 °C / min and hold for 0.5 h for preheating to remove the gas in the mixture; heat it to 1200 °C at a heating rate of 10 °C / min and hold for 1 h for melting. Pour the obtained glass liquid quickly into deionized water for quenching treatment to obtain glass frit.

[0085] Put the glass frit into an oven and dry it at 100 °C for 4 h, then put it into a ball mill and dry mill it at a rotation speed of 500 rpm for 4 h (where the volume ratio of the glass frit to the zirconia grinding balls is 1:1, and the volume of the glass frit and the zirconia grinding balls accounts for 2 / 3 of the total volume of the ball mill tank); wet mill it at a rotation speed of 400 rpm for 8 h (where the volume ratio of the glass frit, the zirconia grinding balls and ethanol is 1:1:1); then dry it at 60 °C for 48 h and screen it with a 500-mesh standard sieve to obtain glass powder with a particle size of about 2 μm.

[0086] Example 5

[0087] Prepare materials according to the following parts by mass: 65 parts of lead oxide, 26 parts of tellurium dioxide, 3.5 parts of silicon dioxide, 3 parts of zinc oxide, 1 part of aluminum oxide, 0.5 part of barium oxide, 0.5 part of indium hydroxide, and 0.5 part of indium tungstate;

[0088] The preparation of the glass frit includes the following steps:

[0089] Put the above raw materials into a mixer and mix for 4 h to obtain a mixed material;

[0090] Put the mixed material into a corundum crucible, and then place the corundum crucible in a high-temperature sintering furnace. Heat from room temperature to 500 °C at a heating rate of 10 °C / min and hold for 0.5 h for preheating to remove the gas in the mixed material; heat to 1200 °C at a heating rate of 10 °C / min and hold for 1 h for melting. Pour the obtained glass liquid quickly into deionized water for quenching treatment to obtain glass frit;

[0091] Put the glass frit into an oven, dry it at 100 °C for 4 h, then put it into a ball mill and dry-mill it at a rotation speed of 500 rpm for 4 h (where the volume ratio of the glass frit to the zirconia grinding balls is 1:1, and the volume of the glass frit and the zirconia grinding balls accounts for 2 / 3 of the total volume of the ball mill tank); wet-mill it at a rotation speed of 400 rpm for 8 h (where the volume ratio of the glass frit, the zirconia grinding balls and ethanol is 1:1:1); then dry it at 60 °C for 48 h and screen it with a 500-mesh standard sieve to obtain glass frit with a particle size of about 2 μm.

[0092] Example 6

[0093] Prepare materials according to the following parts by mass: 70 parts of lead oxide, 21 parts of tellurium dioxide, 3.5 parts of silicon dioxide, 2.5 parts of zinc oxide, 1 part of aluminum oxide, 0.5 part of calcium oxide, 1 part of indium hydroxide, and 0.5 part of indium tungstate;

[0094] The preparation of the glass frit includes the following steps:

[0095] Put the above raw materials into a mixer and mix for 4 h to obtain a mixed material;

[0096] Put the mixed material into a corundum crucible, and then place the corundum crucible in a high-temperature sintering furnace. Heat from room temperature to 500 °C at a heating rate of 10 °C / min and hold for 0.5 h for preheating to remove the gas in the mixed material; heat to 1000 °C at a heating rate of 10 °C / min and hold for 1 h for melting. Pour the obtained glass liquid quickly into deionized water for quenching treatment to obtain glass frit;

[0097] Put the glass frit into an oven and dry it at 100 °C for 4 h. Then put it into a ball mill and dry-mill it at a rotation speed of 500 rpm for 4 h (where the volume ratio of the glass frit to the zirconia grinding balls is 1:1, and the volume of the glass frit and the zirconia grinding balls accounts for 2 / 3 of the total volume of the ball mill tank); wet-mill it at a rotation speed of 400 rpm for 8 h (where the volume ratio of the glass frit, the zirconia grinding balls and ethanol is 1:1:1); then dry it at 60 °C for 48 h and screen it with a 500-mesh standard sieve to obtain glass material with a particle size of about 2 μm.

[0098] Application example

[0099] Prepare silver-aluminum pastes from the glass materials obtained in Examples 1 to 6 respectively;

[0100] The preparation method includes:

[0101] Mix 78 parts of silver powder, 8 parts of aluminum powder, 6 parts of glass material and 8 parts of organic carrier by using a three-roll mill to obtain silver-aluminum paste (with a particle size of 7 μm);

[0102] Among them, the organic carrier includes 90 parts of butyl carbitol, 3 parts of ethyl cellulose, 5 parts of polyamide wax and 2 parts of tributyl phosphate.

[0103] Performance test

[0104] Measure the contact resistance of the metal electrode prepared from the silver-aluminum paste provided by the present invention by using a line transmission model (TLM), Figure 1 which is a schematic diagram of the TLM model;

[0105] Make multiple rectangular contact electrodes with unequal spacings and a length of W on a rectangular sample; when measuring, pass a constant current I between these electrodes respectively, and measure the corresponding voltage V with a voltage probe; according to R = V / I, obtain the total resistance RT(d n ) of each spacing; this resistance is composed of two contact resistances and the resistance of the conductive layer between the electrodes, that is: RT(d n ) = 2×R C +R sh / w×d n ; in the formula, R C is the contact resistance between the electrode and the substrate, and R sh is the sheet resistance of the conductive substrate between the electrodes;

[0106] Measure RT of each spacing in turn according to this method, and then use the measured resistance value as the ordinate and the electrode spacing as the abscissa, and use the linear fitting method to make a relationship graph between RT and d n ;

[0107] If the contact between the substrate and the electrode is an ohmic contact, this straight line should theoretically be a straight line, as Figure 1As shown; the intersection of this straight line and the vertical axis is equal to twice the contact resistance RC, and the intersection with the horizontal axis is equal to the conversion length L T ;

[0108] The test results obtained are shown in Table 1;

[0109] Table 1 Performance test results of the silver-aluminum paste obtained in the application example

[0110]

[0111] As can be seen from Table 1, the silver-aluminum paste for N-type crystalline silicon solar cells prepared by using the frit provided by the present invention can effectively reduce the contact resistance between the metal electrode and the p-Si emitter in the N-type crystalline silicon solar cell, improve the conductivity of the metal electrode, and thus effectively reduce the series resistance of the cell, increase the short-circuit current of the cell, and improve the conversion efficiency of the cell.

[0112] Although the above embodiments have made a detailed description of the present invention, they are only a part of the embodiments of the present invention, rather than all embodiments. Other embodiments can be obtained based on these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A frit, characterized in that, Composed of the following components in parts by mass : 3 - 10 parts of silicon dioxide, 30 - 70 parts of lead oxide, 20 - 50 parts of tellurium dioxide, 1 - 10 parts of zinc oxide, 0.5 - 5 parts of aluminum oxide, 0.5 - 5 parts of alkaline earth metal oxide, 0.5 - 5 parts of regulator, and 0 - 10 parts of boric acid; The regulator includes indium hydroxide and indium tungstate; the mass ratio of indium hydroxide to indium tungstate is 1 - 2:1 - 2; The frit is used for silver - aluminum paste, and the silver - aluminum paste is used for N - type crystalline silicon solar cells.

2. The glass frit according to claim 1, characterized in that, The alkaline earth metal oxide includes one or more of barium oxide, magnesium oxide, and calcium oxide.

3. The preparation method of the glass frit according to any one of claims 1 to 2, characterized in that, Including the following steps: Mix the components included in the frit, and successively carry out melting and quenching treatments to obtain the frit.

4. The preparation method according to claim 3, characterized in that, The temperature of the melting is 1000 - 1200 °C, and the time is 0.5 - 1 h.

5. Application of the frit according to any one of claims 1 - 2 or the frit prepared by the preparation method according to any one of claims 3 - 4 in silver - aluminum paste.

6. A silver-aluminum paste, characterized in that, Including the following components in parts by mass: 70 - 85 parts of silver powder, 5 - 10 parts of aluminum powder, 5 - 10 parts of frit, and 5 - 10 parts of organic carrier; The frit is the frit according to any one of claims 1 - 2 or the frit prepared by the preparation method according to any one of claims 3 - 4.

7. The silver-aluminum paste according to claim 6, wherein By mass, the organic carrier includes the following components: 85 - 95 parts of solvent, 1 - 3 parts of thickener, 3 - 8 parts of thixotropic agent, and 1 - 2 parts of dispersant.

8. The preparation method of the silver-aluminum paste according to any one of claims 6 to 7, characterized in that, Including the following steps: Mix silver powder, aluminum powder, frit, and organic carrier to obtain the silver - aluminum paste.

9. Application of the silver - aluminum paste according to any one of claims 6 - 7 or the silver - aluminum paste prepared by the preparation method according to claim 8 on N - type crystalline silicon solar cells.

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