All-aluminum back surface field aluminum paste for crystalline silicon solar cell and preparation method thereof

Abstract

The invention discloses an all-aluminum back surface field aluminum paste for a crystalline silicon solar cell and a preparation method thereof. The all-aluminum back surface field paste mainly comprises 60-70% aluminum powder, 5-10% nanometer metal oily solution, 1-10% inorganic binder, 10-20% organic binder, 5-30% organic solvent and 1-5% accessory ingredient. According to the aluminum paste prepared by the present invention, the back surface preparing process of an all-aluminum back surface field can be implemented preferably; moreover, the paste has great adhesive force, is easy to be better adhered to silver paste printed afterwards; meanwhile, the paste can be in good contact with a silicon chip through the nanometer metal oily solution added into the paste, the aluminum back surface is prevented from falling off, and good ohm contact can be formed, so that the photoelectric conversion efficiency is increased, and the economic benefits of enterprises are increased.

Claims

1. A preparation method of an all aluminum back surface field aluminum paste for a crystalline silicon solar cell, comprising the following steps: (1) preparation of inorganic binder: adding low melting point glass powder and high melting point glass powder according to a mass percentage of 1:1-2:1 into a blender mixer to mix evenly, loading the mixture into a porcelain crucible, drying for 2h in a drying oven under 160 C., then placing the mixture into a high temperature furnace to smelt for 1.5h under 500 C., performing cold-extraction on the mixture, then drying, pulverizing and screening the mixture to obtain inorganic binder; (2) preparation of organic binder: mixing resin and organic binder according to a mass percentage of 1:1-1:4, then pouring the mixture in a dispersion machine to disperse for 3060 min to obtain transparent and even organic binder after the mixture is dispersed and dissolved, wherein the resin is one or several of rosin, styrax, phenolic resin, polyvinyl chloride resin, amber, shellac, polyester resin, polyamide resin and epoxy resin; (3) preparation of aluminum paste: weighing 60-70% aluminum powder, 5-10% nanometer metal oily solution, 1-10% inorganic binder, 10-20% organic binder, 5-30% organic solvent and 1-10% accessory ingredient by total weight of the aluminum paste, and mixing evenly through the dispersion machine; and (4) preparation of finished product: grinding the aluminum paste mixed in step (3) through a three-roll grinder to 1620 m to obtain the all-aluminum back surface field aluminum paste.

2. The preparation method according to claim 1, wherein the all-aluminum back surface field aluminum paste obtained in the step (4) comprises: 60-70% aluminum powder; 5-10% nanometer metal oily solution; 1-10% inorganic binder; 10-20% organic binder; 5-30% organic solvent; and 1-5% accessory ingredient; wherein the total mass percentage of the components thereof is 100%.

3. The preparation method according to claim 2, wherein the aluminum powder is spherical aluminum powder has an average particle size of 0.8-10 m, a purity greater than 99.8% and a span of 2.0-4.0.

4. The preparation method according to claim 3, wherein the nanometer metal oily solution has an average particle size of 50-100 nm, and an oily solution thereof is one or two of terpineol and butyl carbitol.

5. The preparation method according to claim 2, wherein the nanometer metal oily solution is an oily solution comprising one or several of nanometer aluminum, tin, aluminum-tin and aluminum-silicate, and having a purity greater than 99%.

6. The preparation method according to claim 2, wherein the inorganic binder is core-shell glass powder which is mainly obtained by mixing low melting point glass powder and high melting point glass powder according to a mass percentage of 1:1-2:1, and then heating and smelting, performing cold-extraction, pulverizing and screening, wherein a shell structure of the inorganic binder is the low melting point glass powder, and a core structure is the high melting point glass powder.

7. The preparation method according to claim 6, wherein the low melting point glass powder is a bismuth-series mixture and has a melting point of 350-450 C., the high melting point glass powder is a zinc-series mixture and has a melting point of 550-650 C., and the inorganic binder has a melting point of 480-530 C.

8. The preparation method according to claim 2, wherein the inorganic binder has a particle size D50 of 2-2.5 m and a particle size span (D90+D10)/D50 of 2-3, and has an effect of fractional melting assistance.

9. The preparation method according to claim 2, wherein the accessory ingredient is a reducing accessory ingredient, which is one or several of activated carbon, nanocarbon and conductive carbon, and can prevent the paste from being oxidized too rapidly.

10. The preparation method according to claim 2, wherein the organic binder is mainly mixed by resin and organic binder according to a mass percentage of 1:1-1:4, the viscosity of the organic binder obtained after being mixed and dispersed is 180-900 dpa.Math.s, and the resin is one or several of rosin, styrax, phenolic resin, polyvinyl chloride resin, amber, shellac, polyester resin, polyamide resin and epoxy resin.

Description

DETAILED DESCRIPTION

(1) The contents of the present invention will be further described hereinafter with reference to the embodiments.

(2) The present invention provides an all-aluminum back surface field aluminum paste for a crystalline silicon solar cell, wherein the aluminum paste comprises: 60-70% aluminum powder; 5-10% nanometer metal oily solution; 1-10% inorganic binder; 10-20% organic binder; 5-30% organic solvent; and 1-5% accessory ingredient; wherein the total mass percentage of the components thereof is 100%.

(3) The aluminum powder is spherical aluminum powder with an average particle size of 0.8-10 m, a purity greater than 99.8% and a span of 2.0-4.0.

(4) The nanometer metal oily solution is an oily solution comprising one or several of nanometer aluminum, tin, aluminum-tin and aluminum-silicate, and having a purity greater than 99%, and the nanometer metal oily solution has an average particle size of 50-100 nm, and an oily solution thereof is one or two of terpineol and butyl carbitol.

(5) The inorganic binder is core-shell glass powder which is mainly obtained by mixing low melting point glass powder and high melting point glass powder according to a mass percentage of 1:1-2:1, and then heating and smelting, performing cold-extraction, pulverizing and screening, wherein a shell structure of the inorganic binder is the low melting point glass powder, and a core structure is the high melting point glass powder. The low melting point glass powder is a bismuth-series mixture, has a melting point of 350-450 C. and has an effect of preferential melting assistance, the high melting point glass powder is a zinc-series mixture, has a melting point of 550-650 C., and has an effect of deep melting assistance under a high temperature, and the inorganic binder has a melting point of 480-530 C.

(6) The inorganic binder has a particle size D50 of 2-2.5 m and a particle size span (D90+D10)/D50 of 2-3, and has an effect of fractional melting assistance.

(7) The accessory ingredient is a reducing accessory ingredient, which is one or several of activated carbon, nanocarbon and conductive carbon, and can prevent the paste from being oxidized too rapidly. Meanwhile, the accessory ingredient after being fired has no residuals, is sanitary and environmentally friendly.

(8) The organic binder is mainly mixed by resin and organic binder according to a mass percentage of 1:1-1:4, the viscosity of the organic binder obtained after being mixed and dispersed is 180-900 dpa.Math.s, and the resin is one or several of rosin, styrax, phenolic resin, polyvinyl chloride resin, amber, shellac, polyester resin, polyamide resin and epoxy resin.

(9) The preparation method of the aluminum paste according to the present invention will be expounded in details with reference to several embodiments hereinafter.

Embodiment 1

(10) 1. Preparation of Inorganic Binder

(11) Preparation of inorganic binder: 60% low melting point glass powder and 40% high melting point glass powder by total weight of the inorganic binder were weighed and mixed evenly by a blender mixer, then the mixture was loaded into a porcelain crucible, dried for 2 h in a drying oven under 160 C., then placed into a high temperature furnace to smelt for 1.5 h under 500 C., subjected to cold-extraction, then dried, pulverized and screened.

(12) 2. Preparation of organic binder: 20% phenolic resin and 80% organic solvent by total weight of the organic binder were weighed and mixed, then dispersed on a dispersion machine for 30-60 min to obtain transparent and even organic binder.

(13) 3. Preparation of all-aluminum back surface field aluminum paste for cell:

(14) the nanometer metal oily solution was a composition obtained by mixing aluminum nano-particles, tin nano-particles and terpineol according to a mass percentage of 1:1:1; moreover, 60% aluminum powder, 5% nanometer metal oily solution, 10% inorganic binder, 10% organic binder, 10% organic solvent and 5% activated carbon accessory ingredient by mass ratio of the aluminum paste were weighed, mixed evenly by a dispersion machine, and grinded to 16-20 m by a three-roll grinder to obtain all-aluminum back surface field aluminum paste.

(15) The all-aluminum back surface field for a crystalline silicon solar cell prepared above was silk-screen printed on a 156 mm156 mm polycrystalline silicon wafer to form an all-aluminum back surface through a 250-mesh backless electrode screen printing plate, and fed into a muffle furnace to dry under 240 C. The all-aluminum back surface was not dropped after being dried, then a back electrode was printed at the all-aluminum back surface, dried in the muffle furnace to dry under 220 C., then front surface silver paste was printed on the other side, fed in an infrared fast-sintering meshbeltfurnace to sinter under 790-810 C., while the performances of the paste prepared were tested to satisfy the requirements.

Embodiment 2

(16) 1. Preparation of Inorganic Binder

(17) Preparation of inorganic binder: 55% low melting point glass powder and 45% high melting point glass powder by total weight of the inorganic binder were weighed and mixed evenly by a blender mixer, then the mixture was loaded into a porcelain crucible, dried for 2 h in a drying oven under 160 C., then placed into a high temperature furnace to smelt for 1.5 h under 500 C., subjected to cold-extraction, then dried, pulverized and screened.

(18) 2. Preparation of organic binder: 20% phenolic resin and 80% organic solvent by total weight of the organic binder were weighed and mixed, then dispersed on a dispersion machine for 30-60 min to obtain transparent and even organic binder.

(19) 3. Preparation of all-aluminum back surface field aluminum paste for cell:

(20) the nanometer metal oily solution was a composition obtained by mixing aluminum nano-particles, tin nano-particles and terpineol according to a mass percentage of 1:1:1; moreover, 65% aluminum powder, 5% nanometer metal oily solution, 7% inorganic binder, 12% organic binder, 8% organic solvent and 3% activated carbon accessory ingredient by mass ratio of the aluminum paste were weighed, mixed evenly by a dispersion machine, and grinded to 16-20 m by a three-roll grinder to obtain all-aluminum back surface field aluminum paste.

(21) The stannous all-aluminum back surface field aluminum paste for a crystalline silicon solar cell prepared above was silk-screen printed on a 156 mm156 mm polycrystalline silicon wafer to form an all-aluminum back surface through a 250-mesh backless electrode screen printing plate, and fed into a muffle furnace to dry under 240 C. The all-aluminum back surface was not dropped after being dried, then a back electrode was printed at the all-aluminum back surface, dried in the muffle furnace to dry under 220 C., then front surface silver paste was printed on the other side, fed in an infrared fast-sintering meshbeltfurnace to sinter under 790-810 C., while the performances of the paste prepared were tested to satisfy the requirements.

Embodiment 3

(22) 1. Preparation of Inorganic Binder

(23) Preparation of inorganic binder: 50% low melting point glass powder and 50% high melting point glass powder by total weight of the inorganic binder were weighed and mixed evenly by a blender mixer, then the mixture was loaded into a porcelain crucible, dried for 2 h in a drying oven under 160 C., then placed into a high temperature furnace to smelt for 1.5 h under 500 C., subjected to cold-extraction, then dried, pulverized and screened.

(24) 2. Preparation of organic binder: 20% rosin, 20% phenolic resin and 60% organic solvent by total weight of the organic binder were weighed and mixed, then dispersed on a dispersion machine for 30-60 min to obtain transparent and even organic binder.

(25) 3. Preparation of all-aluminum back surface field aluminum paste for cell:

(26) the nanometer metal oily solution was a composition obtained by mixing aluminum nano-particles, aluminium-tin nano-particles and terpineol according to a mass percentage of 1:1:1; moreover, 62% aluminum powder, 5% nanometer metal oily solution, 8% inorganic binder, 12% organic binder, 8% organic solvent and 5% activated carbon accessory ingredient by mass ratio of the aluminum paste were weighed, mixed evenly by a dispersion machine, and grinded to 16-20 m by a three-roll grinder to obtain all-aluminum back surface field aluminum paste.

(27) The stannous all-aluminum back surface field aluminum paste for a crystalline silicon solar cell prepared above was silk-screen printed on a 156 mm156 mm polycrystalline silicon wafer to form an all-aluminum back surface through a 250-mesh backless electrode screen printing plate, and fed into a muffle furnace to dry under 240 C. The all-aluminum back surface was not dropped after being dried, then a back electrode was printed at the all-aluminum back surface, dried in the muffle furnace to dry under 220 C., then front surface silver paste was printed on the other side, fed in an infrared fast-sintering meshbeltfurnace to sinter under 790-810 C., while the performances of the paste prepared were tested to satisfy the requirements.

Embodiment 4

(28) 1. Preparation of Inorganic Binder

(29) Preparation of inorganic binder: 65% low melting point glass powder and 35% high melting point glass powder by total weight of the inorganic binder were weighed and mixed evenly by a blender mixer, then the mixture was loaded into a porcelain crucible, dried for 2 h in a drying oven under 160 C., then placed into a high temperature furnace to smelt for 1.5 h under 500 C., subjected to cold-extraction, then dried, pulverized and screened.

(30) 2. Preparation of organic binder: 20% phenolic resin and 80% organic solvent by total weight of the organic binder were weighed and mixed, then dispersed on a dispersion machine for 30-60 min to obtain transparent and even organic binder.

(31) 3. Preparation of all-aluminum back surface field aluminum paste for cell:

(32) the nanometer metal oily solution was a composition obtained by mixing aluminum nano-particles, aluminum-silicate nano-particles and terpineol according to a mass percentage of 1:1:1; moreover, 60% aluminum powder, 6% nanometer metal oily solution, 7% inorganic binder, 11% organic binder, 12% organic solvent and 3% activated carbon accessory ingredient by mass ratio of the aluminum paste were weighed, mixed evenly by a dispersion machine, and grinded to 16-20 m by a three-roll grinder to obtain all-aluminum back surface field aluminum paste.

(33) The stannous all-aluminum back surface field aluminum paste for a crystalline silicon solar cell prepared above was silk-screen printed on a 156 mm156 mm polycrystalline silicon wafer to form an all-aluminum back surface through a 250-mesh backless electrode screen printing plate, and fed into a muffle furnace to dry under 240 C. The all-aluminum back surface was not dropped after being dried, then a back electrode was printed at the all-aluminum back surface, dried in the muffle furnace to dry under 220 C., then front surface silver paste was printed on the other side, fed in an infrared fast-sintering meshbeltfurnace to sinter under 790-810 C., while the performances of the paste prepared were tested to satisfy the requirements.

Embodiment 5

(34) 1. Preparation of Inorganic Binder

(35) Preparation of inorganic binder: 60% low melting point glass powder and 40% high melting point glass powder by total weight of the inorganic binder were weighed and mixed evenly by a blender mixer, then the mixture was loaded into a porcelain crucible, dried for 2 h in a drying oven under 160 C., then placed into a high temperature furnace to smelt for 1.5 h under 500 C., subjected to cold-extraction, then dried, pulverized and screened.

(36) 2. Preparation of organic binder: 20% rosin, 20% phenolic resin and 60% organic solvent by total weight of the organic binder were weighed and mixed, then dispersed on a dispersion machine for 30-60 min to obtain transparent and even organic binder.

(37) 3. Preparation of all-aluminum back surface field aluminum paste for cell:

(38) the nanometer metal oily solution was a composition obtained by mixing aluminum nano-particles, aluminum-tin nano-particles, aluminum-silicate nano-particles and terpineol according to a mass percentage of 1:1:1:1; moreover, 62% aluminum powder, 5% nanometer metal oily solution, 8% inorganic binder, 12% organic binder, 8% organic solvent and 5% activated carbon accessory ingredient by mass ratio of the aluminum paste were weighed, mixed evenly by a dispersion machine, and grinded to 16-20 m by a three-roll grinder to obtain all-aluminum back surface field aluminum paste.

(39) The stannous all-aluminum back surface field aluminum paste for a crystalline silicon solar cell prepared above was silk-screen printed on a 156 mm156 mm polycrystalline silicon wafer to form an all-aluminum back surface through a 250-mesh backless electrode screen printing plate, and fed into a muffle furnace to dry under 240 C. The all-aluminum back surface was not dropped after being dried, then a back electrode was printed at the all-aluminum back surface, dried in the muffle furnace to dry under 220 C., then front surface silver paste was printed on the other side, fed in an infrared fast-sintering meshbeltfurnace to sinter under 790-810 C., while the performances of the paste prepared were tested to satisfy the requirements.

Embodiment 6

(40) 1. Preparation of Inorganic Binder

(41) Preparation of inorganic binder: 50% low melting point glass powder and 50% high melting point glass powder by total weight of the inorganic binder were weighed and mixed evenly by a blender mixer, then the mixture was loaded into a porcelain crucible, dried for 2 h in a drying oven under 160 C., then placed into a high temperature furnace to smelt for 1.5 h under 500 C., subjected to cold-extraction, then dried, pulverized and screened.

(42) 2. Preparation of organic binder: 20% phenolic resin and 80% organic solvent by total weight of the organic binder were weighed and mixed, then dispersed on a dispersion machine for 30-60 min to obtain transparent and even organic binder.

(43) 3. Preparation of all-aluminum back surface field aluminum paste for cell:

(44) 70% nanometer metal oily solution was a composition obtained by mixing aluminum nano-particles, aluminium-tin nano-particles, aluminum-silicate nano-particles and terpineol according to a mass percentage of 1:1:1:1; moreover, 70% aluminum powder, 6% nanometer metal oily solution, 6% inorganic binder, 12% organic binder, 8% organic solvent and 3% activated carbon accessory ingredient by mass ratio of the aluminum paste were weighed, mixed evenly by a dispersion machine, and grinded to 16-20 m by a three-roll grinder to obtain all-aluminum back surface field aluminum paste.

(45) The stannous all-aluminum back surface field aluminum paste for a crystalline silicon solar cell prepared above was silk-screen printed on a 156 mm156 mm polycrystalline silicon wafer to form an all-aluminum back surface through a 250-mesh backless electrode screen printing plate, and fed into a muffle furnace to dry under 240 C. The all-aluminum back surface was not dropped after being dried, then a back electrode was printed at the all-aluminum back surface, dried in the muffle furnace to dry under 220 C., then front surface silver paste was printed on the other side, fed in an infrared fast-sintering meshbeltfurnace to sinter under 790-810 C., while the performances of the paste prepared were tested to satisfy the requirements.

(46) The performances of the products obtained in the five embodiments above were tested, wherein the results were as shown in Table 1:

(47) TABLE-US-00001 TABLE 1 Embodiment Embodiment Embodiment Embodiment Embodiment Embodiment Performance index 1 2 3 4 5 6 Contact 7.5 6.3 7.1 8.3 6.0 5.3 resistance/m-cm.sup.2 Adhesive 4.5 5.1 5.0 3.1 5.2 5.1 performance between aluminum layer and back Adhesive No slabbing No slabbing No slabbing No slabbing No slabbing No slabbing performance between aluminum Boiling resistance No bubbles in No bubbles in No bubbles in No bubbles in No bubbles in No bubbles in the coating the coating the coating the coating the coating the coating and no ash and no ash and no ash and no ash and no ash and no ash