Emulsified and dispersed organic carrier for solar cell silver paste as well as preparation and application of emulsified and dispersed organic carrier

Abstract

The invention discloses an emulsified and dispersed organic carrier for solar cell silver paste. The emulsified and dispersed organic carrier is prepared from the following raw materials in percentage by mass: 5-10% of a compound resin composition, 0.5-3% of a thixotropic agent, 2-10% of a dispersing agent, 2-10% of silicone oil, 0.2-2% of a rheology modifier and the balance of an organic solvent. Through the combined action of the non-polar elastomer resin and the thickening resin, the raw materials can be more uniformly emulsified in the organic carrier, and the stability of the organic carrier is improved. The thixotropic agent is introduced, and after the organic carrier is emulsified and dispersed, the height-width ratio of the grid line after silver paste printing is improved. The silver paste is dispersed by stages through the three stages of stator and rotor emulsifying heads, so that the rheological property of the silver paste can be effectively improved, the good net passing performance is achieved, and meanwhile the height-width ratio of grid lines can be guaranteed. When the thin grid line is applied to a TOPCon front fine grid, the photoelectric conversion efficiency of a TOPCon battery piece is improved, and the printing performance of a narrow grid line is improved.

Description

Technical Field

[0001] The present invention relates to the field of selection of conductive materials, and in particular to an organic carrier for emulsified and dispersed solar cell silver paste and its preparation and application. Background Art

[0002] TOPCon (Tunneling Oxide Passivated Contact) solar cells have excellent passivation performance, high bifaciality and low temperature coefficient, and have become one of the mainstream technical routes in the photovoltaic industry. With the advancement of technology, in order to reduce costs and increase efficiency, higher requirements are placed on the grid lines of the battery, requiring the grid lines to have narrower and taller line shapes. Therefore, higher requirements are also placed on the silver paste used to prepare the grid lines. Under the condition of preparing narrow grid lines, the durability of printing is improved, and it is required to maintain the grid line after multiple printings, and the aspect ratio of the grid line will not change. The existing silver paste for grid lines is not evenly dispersed, resulting in unstable paste viscosity. Problems such as broken grids and uneven thickness are prone to occur during printing. Therefore, it is crucial to develop a silver paste that can prepare narrow grid lines and print stably.

[0003] Chinese invention patent application CN119092175A discloses a front fine grid silver paste and battery for N-type TOPCON cells. The polymer nanosilver solution in the silver paste improves the contact performance during the laser-assisted sintering of N-type TOPCON cells, reduces recombination, and increases the open circuit voltage and short circuit current. However, the aspect ratio of the prepared grid lines is not good, and the preparation cost of the silver paste is high. Chinese invention patent CN114360766B discloses a silver paste for the front electrode of crystalline silicon solar cells with a high silver content and a preparation method. By improving the selection of silver powder and the organic carrier, the silver content in the paste can be effectively increased, and the silver powder and glass powder can be evenly dispersed, thereby forming a denser structure after printing and sintering, effectively reducing the series resistance of the crystalline silicon solar cell, improving the conversion efficiency, and can be used for narrower grid widths. The printed fine grids are continuous and flat without broken grids. However, the amount of silver powder added is too high, and the preparation cost of the silver paste is high. Summary of the Invention

[0004] In order to develop a silver paste that can prepare fine grids, print stably, and be low in cost, the first aspect of the present invention provides an emulsified dispersed organic carrier for solar cell silver paste, the raw materials of which include, by mass percentage, 5-10% of a compounded resin combination, 0.5-3% of a thixotropic agent, 2-10% of a dispersant, 2-10% of a silicone oil, 0.2-2% of a rheology modifier, and the organic solvent is supplemented to 100%.

[0005] As an embodiment, the compounded resin combination includes a non-polar elastomer resin and a thickening resin, and the weight ratio of the non-polar elastomer resin to the thickening resin is 3:(1-2).

[0006] As an embodiment, the non-polar elastomeric resin includes at least one of a styrene polymer, a poly-α-methylstyrene polymer, a styrene-butadiene-styrene block copolymer, a hydrogenated styrene-butadiene-styrene block copolymer, or a styrene-isoprene-styrene block copolymer.

[0007] As an embodiment, the non-polar elastomeric resin is hydrogenated styrene-butadiene-styrene block copolymer (SEBS).

[0008] As an embodiment, the non-polar elastomer resin is of the type KRATON G1652.

[0009] As an embodiment, the thickening resin includes at least one of ethyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, cellulose acetate butyrate, polyvinyl butyral, rosin resin or acrylic acid and modified resins thereof.

[0010] As an embodiment, the thickening resin is cellulose acetate butyrate or ethyl cellulose.

[0011] As an embodiment, the thickening resin is Eastman CAB-551-0.01 or Dow STD-4.

[0012] As an embodiment, the thixotropic agent includes at least one of hydrogenated castor oil derivatives, polyamide wax or fumed silica.

[0013] As an embodiment, the thixotropic agent is polyamide wax.

[0014] As an embodiment, the model of the thixotropic agent is ET2020.

[0015] As an embodiment, the dispersant includes at least one of lauryl alcohol polyoxyethylene ether, isomeric alcohol polyoxyethylene ether, oleic acid, sodium dodecylbenzenesulfonate, N,N-dimethyldecylamine, tallow propylene diamine oleate, and dispersant TDO.

[0016] As an embodiment, the viscosity of the silicone oil at 25° C. is 10-500 cps.

[0017] As an embodiment, the rheology modifier includes at least nano-silicon dioxide; the particle size of the nano-silicon dioxide is 50-100 nm.

[0018] As an embodiment, the model of the rheology regulator is Shin-Etsu QSG-100.

[0019] As an embodiment, the organic solvent includes at least one of diethylene glycol butyl ether acetate, diethylene glycol butyl ether, alcohol ester dodecanol, hexadecanol ester, dimethyl adipate, benzyl benzoate, ethylene glycol phenyl ether acetate, dimethyl phthalate, terpineol, tributyl citrate or diethylene glycol dibutyl ether.

[0020] A second aspect of the present invention provides a method for preparing an emulsified dispersed organic vehicle for solar cell silver paste, comprising the following steps:

[0021] S1: mixing a non-polar elastomer resin with 33 wt% of an organic solvent to obtain a pre-solution P1;

[0022] S2: Mixing the thickening resin with 33 wt% of an organic solvent to obtain a pre-solution P2;

[0023] S3: mixing the thixotropic agent with 34 wt% of an organic solvent to obtain a pre-solution P3;

[0024] S4: pre-dissolve P1, pre-dissolve P2, pre-dissolve P3 are mixed with a dispersant, silicone oil, and a rheology modifier, and subjected to three-stage graded dispersion to obtain an emulsified dispersed organic carrier for solar cell silver paste.

[0025] As an embodiment, the parameters of the three-stage dispersion include: first-stage coarse dispersion: speed 1000-3000 rpm, time 3-5 min; second-stage fine dispersion: speed 5000-8000 rpm, time 8-12 min, shear rate > 1×10 4 s -1 ; Three-stage homogenization: speed 2000-3000rpm, time 3-5min.

[0026] As an embodiment, the mixing temperature in step S1 is 65-90°C, the mixing temperature in step S2 is 65-90°C, and the mixing temperature in step S3 is 65-90°C.

[0027] As an embodiment, the mixing time in step S1 is 30-60 min, the mixing time in step S2 is 30-60 min, and the mixing time in step S3 is 30-60 min.

[0028] As an embodiment, the temperature during the three-stage dispersion process is ≤80°C, and the temperature fluctuation range is 0-2°C.

[0029] As an embodiment, the three-stage graded dispersion adopts a three-stage stator-rotor emulsification head for graded dispersion, and the rotor linear speed of the three-stage stator-rotor emulsification head is ≥20m / s.

[0030] As an embodiment, the viscosity of the prepared organic vehicle at 25° C. is 10-50 Pa·s.

[0031] The organic carrier prepared in this application adopts a unique high-shear emulsification head technology. By optimizing the emulsification head parameters, the synergistic improvement of the slurry rheological properties and the printing structure is achieved, which can effectively improve the grid line aspect ratio and printing durability of the photovoltaic conductive silver paste, and improve the photoelectric conversion efficiency of crystalline silicon solar cells.

[0032] The third aspect of the present invention provides an application of an emulsified dispersed organic carrier for solar cell silver paste, which is applied to the preparation of TOPCon solar cell front silver paste.

[0033] As an embodiment, the raw materials for preparing the TOPCon solar cell front silver paste include, by weight, 85-92 parts of silver powder, 1-3 parts of glass powder, and 6-12 parts of the organic vehicle prepared above.

[0034] As an embodiment, the silver powder is spherical silver powder with a tap density of ≥5.5g / cm 3 , D50 particle size is 1.0-2.0μm.

[0035] As an embodiment, the glass powder is Bi2O3-TeO2 system glass powder with a softening point of 450-500°C.

[0036] As an embodiment, the method for preparing the front silver paste of the TOPCon solar cell comprises the following steps:

[0037] Prepare organic carrier;

[0038] Silver powder, glass powder and the organic carrier prepared above are mixed, ground by three rollers to a fineness of ≤3 μm, filtered and then packaged.

[0039] As an embodiment, the mixing frequency is 400-600 rpm, and the mixing time is 20-40 min.

[0040] As an embodiment, the filtration is performed using a 400-mesh filter.

[0041] As an embodiment, the roller gap of the three-roller grinding is 10-30 μm, the linear speed difference of the three-roller grinding is 1:(2-3), and the number of cycle grinding times is ≥3 times.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] (1) The organic carrier for the emulsified and dispersed solar cell silver paste of the present invention adopts a combination of a non-polar elastomer resin and a thickening resin, which can make the raw materials more uniformly emulsified in the organic carrier, stabilize the viscosity of the paste, and is less likely to cause grid breakage problems during printing. The thickness is uniform and the stability of the organic carrier can be improved.

[0044] (2) The organic carrier for the emulsified and dispersed solar cell silver paste of the present invention introduces a thixotropic agent. After the organic carrier is emulsified and dispersed, the interfacial bonding force between the silver powder and the organic carrier is enhanced, which is beneficial to improving the aspect ratio of the grid lines after silver paste printing, improving conductivity and reducing shading rate.

[0045] (3) The organic carrier for the emulsified dispersed solar cell silver paste of the present invention uses silicone oil with a viscosity of 10-500 cps, which can make the silver powder and glass powder dispersed more finely in the organic carrier, which is beneficial to improving the mesh-passing property of the silver paste during the printing process, and the paste is not prone to sedimentation and stratification during storage, and the quality is stable between batches.

[0046] (4) The organic carrier for the emulsified and dispersed solar cell silver paste of the present invention is graded and dispersed by a three-stage stator-rotor emulsification head, which can effectively improve the rheological properties of the silver paste, have good mesh passing properties, and at the same time ensure the aspect ratio of the grid line.

[0047] (5) The silver paste prepared from the emulsified dispersed solar cell silver paste with an organic carrier, glass powder and silver powder is applied to the TOPCon front fine grid, thereby improving the photoelectric conversion efficiency of the TOPCon cell and the printing performance of the narrow grid line. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 A three-stage stator-rotor emulsification head for preparing organic carriers for emulsified and dispersed solar cell silver paste;

[0049] In the figure: 1. Rotor; 2. Stator. DETAILED DESCRIPTION

[0050] Example 1

[0051] The invention discloses an organic carrier for emulsified dispersed solar cell silver paste. The raw materials for preparation thereof include, by mass percentage, 15% of a compound resin combination, 3% of a thixotropic agent, 5% of a dispersant, 5% of silicone oil, 1% of a rheology regulator, and an organic solvent supplemented to 100%.

[0052] The compounded resin combination comprises a non-polar elastomer resin and a thickening resin in a weight ratio of 3:2.

[0053] The non-polar elastomer resin is a hydrogenated styrene-butadiene-styrene block copolymer purchased from Kraton, USA, with the model number KRATON G1652.

[0054] The thickening resin is cellulose acetate butyrate, purchased from Eastman, model number Eastman CAB-551-0.01.

[0055] The thixotropic agent is polyamide wax purchased from Disparon, model ET2020.

[0056] The dispersant is Dispersant TDO, purchased from Nouryon.

[0057] The silicone oil has a viscosity of 200 cps at 25° C. and is purchased from Wacker, model AK200.

[0058] The rheology regulator was purchased from Xinyue, model number QSG-100.

[0059] The solvent is diethylene glycol butyl ether acetate.

[0060] A method for preparing an emulsified dispersed organic carrier for solar cell silver paste comprises the following steps:

[0061] S1: mixing a non-polar elastomer resin with 33 wt% of an organic solvent until completely dissolved to obtain a presolution P1;

[0062] S2: Mixing the thickening resin with 33 wt% of an organic solvent to form a transparent viscous solution to obtain a pre-solution P2;

[0063] S3: Mixing the thixotropic agent with 34 wt% of an organic solvent to form a uniform suspension to obtain a presolution P3;

[0064] S4: pre-dissolve P1, pre-dissolve P2, pre-dissolve P3 are mixed with a dispersant, silicone oil, and a rheology modifier, and subjected to three-stage graded dispersion to obtain an emulsified dispersed organic carrier for solar cell silver paste.

[0065] The parameters of the three-stage dispersion include: first-stage coarse dispersion: speed 2500 rpm, time 3 min; second-stage fine dispersion: speed 6000 rpm, time 10 min, shear rate 1×10 5 s -1 ; Three-stage homogenization: speed 2000rpm, time 5min.

[0066] The three-stage stator and rotor emulsification head (see Figure 1 )The linear speed of rotor 1 is ≥20m / s.

[0067] The stator of the three-stage stator-rotor emulsification head is shown in Figure 1 Middle 2.

[0068] The mixing temperature in step S1 is 75°C, the mixing temperature in step S2 is 80°C, and the mixing temperature in step S3 is 70°C.

[0069] The mixing time in step S1 is 60 min, the mixing time in step S2 is 40 min, and the mixing time in step S3 is 30 min.

[0070] The viscosity of the prepared organic vehicle at 25° C. is 35 Pa·s.

[0071] The raw materials for preparing a TOPCon solar cell front silver paste include, by weight, 90 parts of silver powder, 1.5 parts of glass powder, and 8.5 parts of the organic vehicle prepared above.

[0072] The silver powder is spherical silver powder with a tap density of ≥5.8g / cm 3 , D50 particle size is 1.5μm.

[0073] The glass powder is Bi2O3-TeO2 system glass powder with a softening point of 450-500°C.

[0074] The method for preparing the front silver paste of the TOPCon solar cell comprises the following steps:

[0075] Prepare organic carrier;

[0076] Silver powder, glass powder and the organic carrier prepared above were mixed, and the mixture was ground by three rollers to a fineness of ≤1.5 μm, filtered through a 400-mesh filter, and then packaged.

[0077] The mixing frequency is 500 rpm and the mixing time is 30 min.

[0078] The roller gap of the three-roller grinding is 20 μm, the linear speed difference of the three-roller grinding is 1:3, and the number of cycle grinding is 3 times.

[0079] Example 2

[0080] An organic carrier for emulsified and dispersed solar cell silver paste, the specific implementation method is the same as that of Example 1,

[0081] A method for preparing an emulsified dispersed organic carrier for solar cell silver paste comprises the following steps:

[0082] The composite resin, thixotropic agent, dispersant, silicone oil, rheology modifier and organic solvent were mixed by conventional process at a rotation speed of 1000 rpm for 60 minutes to obtain an organic carrier.

[0083] A TOPCon solar cell front silver paste and a preparation method thereof, wherein the specific implementation manner is the same as that of Example 1, except that the organic carrier prepared in Example 2 is used.

[0084] Example 3

[0085] An organic carrier for emulsified and dispersed solar cell silver paste and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that the preparation raw materials do not include a rheology modifier.

[0086] A TOPCon solar cell front silver paste and a preparation method thereof, the specific implementation manner is the same as that of Example 1.

[0087] Example 4

[0088] An organic carrier for emulsified and dispersed solar cell silver paste and a preparation method thereof, the specific implementation method is the same as that of Example 1, except that the preparation raw materials include, by mass percentage, 16% of a compounded resin combination, 2% of a thixotropic agent, 5% of a dispersant, 5% of silicone oil, 1% of a rheology modifier, and the organic solvent is supplemented to 100%.

[0089] The compounded resin combination comprises a non-polar elastomer resin and a thickening resin in a weight ratio of 3:1.

[0090] The non-polar elastomer resin is a hydrogenated styrene-butadiene-styrene block copolymer purchased from Kraton, USA, with the model number KRATON G1652.

[0091] The thickening resin is cellulose acetate butyrate, purchased from Eastman, model number Eastman CAB-551-0.01.

[0092] The thixotropic agent is hydrogenated castor oil, purchased from Haian (Linyi) Guoli Chemical Co., Ltd., with the model number of PEG-40.

[0093] A TOPCon solar cell front silver paste and a preparation method thereof, the specific implementation manner is the same as that of Example 1.

[0094] Example 5

[0095] An organic carrier for emulsified and dispersed solar cell silver paste and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that the silicone oil has a viscosity of 500 cps at 25° C. and is purchased from Wacker, model AK500.

[0096] A TOPCon solar cell front silver paste and a preparation method thereof, the specific implementation manner is the same as that of Example 1.

[0097] Example 6

[0098] An organic carrier for emulsified and dispersed solar cell silver paste and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that the thickening resin is ethyl cellulose purchased from Dow, model number STD-10.

[0099] A TOPCon solar cell front silver paste and a preparation method thereof, the specific implementation manner is the same as that of Example 1.

[0100] Performance Testing

[0101] 1. Viscosity stability: The test is performed using a rotational viscometer, which measures the torque of the rotor as it rotates in the sample to calculate the viscosity.

[0102] 2. Thixotropic index: It is evaluated by the viscosity ratio of the viscometer tested at different speeds. Two speeds are selected to test the thixotropic index at 100RPM (high shear) and 10RPM (low shear).

[0103] 3. Printing line width / line height: High-precision measurement is performed using a 3D microscope (confocal microscope).

[0104] 4. Cell Efficiency: After silver paste printing, the cells were tested using a photovoltaic Halm IV tester to obtain current-voltage characteristic curves under different lighting conditions, thereby evaluating the cell efficiency. The cells used were TOPCon monocrystalline silicon cells with a size of 182×183mm, and the silver paste printing amount was 26-34μg / cell.

[0105] The test results are shown in Table 1.

[0106] Table 1

[0107]

[0108] This application adopts three-stage emulsification and dispersion technology (linear speed ≥ 20m / s, shear rate > 1×10 4 / s), combined with a rheology regulator, and a compound system of non-polar resin and thickening resin, significantly improves the rheological properties of silver paste, achieving ultra-fine grid printing (line width ≤ 20μm) and aspect ratio ≥ 0.5, increasing TOPCon cell efficiency by more than 0.2%. At the same time, the paste stability (viscosity deviation <3%) is better than that of traditional processes.

Claims

1. An organic carrier for emulsified and dispersed solar cell silver paste, characterized in that: The raw materials prepared by mass percentage include 5-10% of compound resin combination, 0.5-3% of thixotropic agent, 2-10% of dispersant, 2-10% of silicone oil, 0.2-2% of rheology regulator, and organic solvent is supplemented to 100%.

2. The organic carrier for the emulsified and dispersed solar cell silver paste according to claim 1, characterized in that: The compounded resin combination comprises a non-polar elastomer resin and a thickening resin, and the weight ratio of the non-polar elastomer resin to the thickening resin is 3:(1-2).

3. The organic carrier for the emulsified and dispersed solar cell silver paste according to claim 2, characterized in that: The non-polar elastomeric resin includes at least one of a styrene polymer, a poly-α-methylstyrene polymer, a styrene-butadiene-styrene block copolymer, a hydrogenated styrene-butadiene-styrene block copolymer, or a styrene-isoprene-styrene block copolymer.

4. The organic carrier for the emulsified and dispersed solar cell silver paste according to claim 2, characterized in that: The thickening resin includes at least one of ethyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, cellulose acetate butyrate, polyvinyl butyral, rosin resin or acrylic acid and modified resins thereof.

5. The organic carrier for the emulsified and dispersed solar cell silver paste according to claim 2, characterized in that: The thixotropic agent includes at least one of hydrogenated castor oil derivatives, polyamide wax or fumed silica.

6. The organic carrier for the emulsified and dispersed solar cell silver paste according to claim 2, characterized in that: The viscosity of the silicone oil at 25° C. is 10-500 cps.

7. A method for preparing an organic carrier for an emulsified and dispersed solar cell silver paste according to any one of claims 2 to 6, characterized in that: The following steps are involved: S1: mixing a non-polar elastomer resin with 33 wt% of an organic solvent to obtain a pre-solution P1; S2: Mixing the thickening resin with 33 wt% of an organic solvent to obtain a pre-solution P2; S3: mixing the thixotropic agent with 34 wt% of an organic solvent to obtain a pre-solution P3; S4: pre-dissolve P1, pre-dissolve P2, pre-dissolve P3 are mixed with a dispersant, silicone oil, and a rheology modifier, and subjected to three-stage graded dispersion to obtain an emulsified dispersed organic carrier for solar cell silver paste.

8. The method for preparing an organic carrier for an emulsified and dispersed solar cell silver paste according to claim 7, characterized in that: The parameters of the three-stage dispersion include: first-stage coarse dispersion: rotation speed 1000-3000 rpm, time 3-5 min; second-stage fine dispersion: rotation speed 5000-8000 rpm, time 8-12 min, shear rate > 1×10 4 s -1 ; Three-stage homogenization: speed 2000-3000rpm, time 3-5min.

9. The method for preparing an emulsified and dispersed organic carrier for solar cell silver paste according to claim 7, characterized in that: The temperature during the three-stage dispersion process is ≤80°C, and the temperature fluctuation range is 0-2°C.

10. An application of the emulsified and dispersed organic carrier for solar cell silver paste according to any one of claims 2 to 6, characterized in that: Used in the preparation of silver paste for the front side of TOPCon solar cells.

Images