CN103021511B - A kind of crystal silicon solar energy battery front electrode silver slurry and preparation method thereof - Google Patents

Abstract

The invention provides a kind of crystal silicon solar energy battery front electrode silver slurry, described silver slurry comprises silver powder, the first glass dust, the second glass dust and organic components; The gross weight of starching taking silver is as benchmark, and the content of described silver powder is 75-90 % by weight, and the content of described the first glass dust is 1-3 % by weight, and the content of described the second glass dust is 1-5 % by weight, and the content of described organic component is 6-25 % by weight; The softening point of described the first glass dust is 350-550 DEG C, and the softening point of described the second glass dust is 550-650 DEG C, and differs at least 70 DEG C between the first glass dust and the softening point of the second glass dust. The present invention also provides the preparation method of this electrode silver plasm. With electrode silver plasm of the present invention can be under wider sintering temperature sintering, and the series resistance of the solar cell obtaining is low, optoelectronic transformation efficiency is high.

Description

A kind of front electrode silver paste of crystalline silicon solar cell and preparation method thereof

technical field

The invention relates to the field of crystalline silicon solar cells, in particular to a silver paste for a front electrode of a crystalline silicon solar cell and a preparation method thereof.

Background technique

Crystalline silicon solar cells have developed rapidly as the main solar photovoltaic power generation unit. The front side of the solar cell is the side that directly receives solar energy, and a multi-layer structure is used to achieve the widest receiving spectral line and the least light reflection consumption. The front side of conventional commercial crystalline silicon solar cells includes four main structures of silver electrode grid lines, non-conductive anti-reflection layer, n-type diffusion layer, and p-n junction region. The front electrode is an important part of crystalline silicon solar cells. The contact resistance between the electrode and n-type silicon, the conductivity of the electrode itself, and the aspect ratio of the electrode have a direct impact on its photoelectric conversion efficiency, which has become the main research in this industry. one of the directions.

At present, the production method of the front electrode of commercial crystalline silicon solar cells usually adopts printing and inkjet printing of conductive silver paste to form a grid line structure with as large an aspect ratio as possible, and then undergoes a rapid sintering process at room temperature to around 780°C to form a grid line structure similar to n Conductive electrodes that are in close contact with the diffusion layer. In this sintering process, the corrosive glass frit contained in the slurry, such as the commonly used lead borosilicate glass frit, is gradually melted and deposited during the heating process, and spread between the silicon wafer and the silver powder to dissolve the n-type silicon surface. Ag powder in ARC (anti-reflection) film and paste. Subsequently, during the cooling process, the Ag supersaturated glass frit precipitates Ag on the n-type silicon surface, forming an inverted pyramid-shaped Ag island to conduct the photo-generated current to the upper Ag grid line. The current conduction path is composed of the following parts: n-type silicon-Ag island-glass layer-Ag electrode. The actual output power of crystalline silicon solar cells is greatly affected by the resistance of the current path. Generally, the Ag electrode itself is required to have low resistance, the glass layer is thin and the conductivity is relatively high. The number of Ag islands is large and the volume should not be too large. The series resistance in the whole loop improves the overall photoelectric conversion efficiency of the crystalline silicon solar cell. However, the series resistance of the front electrode of the existing solar cell is relatively large, so that the photoelectric conversion efficiency is low.

Contents of the invention

The invention aims to solve the defects of large series resistance and low photoelectric conversion efficiency in the existing solar cell front electrode silver paste, thereby providing a solar cell front electrode silver paste with small series resistance and high photoelectric conversion efficiency and a preparation method thereof.

Reducing the low resistance of the Ag electrode itself requires that the Ag electrode be as dense as possible during the sintering process, but the effective sintering time of the current commercial sintering process is very short (<10s), and the Ag electrode needs molten glass frit to help sinter; in addition, the glass frit needs to be deposited Spread the ARC film on the dissolved n-type silicon surface between the silicon wafer and the silver powder.

The inventors of the present invention have obtained through a large number of experiments that if a single glass frit is used in the common front silver paste, contradictory phenomena will appear when the above two functions are realized simultaneously. At high temperature (<740°C) the glass frit cannot be fused and deposited effectively to spread the ARC film on the surface of the n-type silicon dissolved between the silicon wafer and the silver powder, and the sintering activity of the Ag powder is not enough at this time, so it is difficult to sinter densely; increase the sintering temperature by 20 If the temperature is higher than ℃ or the sintering time is increased, the glass frit used for sintering between the silver powders will also be deposited, resulting in many problems such as incomplete sintering of the Ag electrode, excessive thickness of the glass layer, excessive corrosion of the silicon wafer, and burn-through of the p/n junction. .

The invention provides a silver paste for the front electrode of a crystalline silicon solar cell, the silver paste includes silver powder, a first glass powder, a second glass powder and an organic component; based on the total weight of the silver paste, the content of the silver powder 75-90wt%, the content of the first glass powder is 1-3wt%, the content of the second glass powder is 1-5wt%, the content of the organic component is 6-25wt%; The softening point of one glass powder is 350-550°C, the softening point of the second glass powder is 550-650°C, and the difference between the softening points of the first glass powder and the second glass powder is at least 70°C.

The invention also provides a preparation method of electrode silver paste, which comprises mixing and grinding silver powder, first glass powder, second glass powder and organic components.

The silver paste of the front electrode of the crystalline silicon solar cell of the present invention is obtained by adding two kinds of glass frit powders with different softening points to the silver paste, wherein the first glass frit is used to corrode the anti-reflection film during the sintering process, and the second glass frit is used to corrode the antireflection film during the sintering process. In the process, it is used to help the silver powder sinter, so as to effectively control the degree of corrosion on the surface of the silicon wafer to prevent burning through the p/n junction area, and at the same time control the thickness of the glass layer between the emitter and the silver electrode, which is beneficial to the paste in a wider Stable and excellent electrical performance indicators can be obtained within the sintering temperature window.

detailed description

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

The invention provides a silver paste for the front electrode of a crystalline silicon solar cell, the silver paste includes silver powder, a first glass powder, a second glass powder and an organic component; based on the total weight of the silver paste, the content of the silver powder 75-90wt%, the content of the first glass powder is 1-3wt%, the content of the second glass powder is 1-5wt%, the content of the organic component is 6-25wt%; The softening point of one glass powder is 350-550°C, the softening point of the second glass powder is 550-650°C, and the difference between the softening points of the first glass powder and the second glass powder is at least 70°C.

The difference between the softening points of the first glass powder and the second glass powder is at least 70°C to ensure that the first glass powder is fully settled and wetted under suitable process conditions, especially at high temperature or long sintering time. On the surface of the crystalline silicon substrate, at the same time, the second glass powder will not be deposited in large quantities to increase the thickness of the glass layer and affect the series resistance.

The softening point of the first glass powder should not be lower than 350°C, otherwise the organic matter in the slurry has not been decomposed and volatilized, and its discharge path will be filled with molten glass, which will cause residual carbon, internal pores, internal stress, etc. Many questions. The softening point should not be higher than 550°C, otherwise it will be difficult to effectively deposit and spread between the silicon wafer and the silver powder.

The softening point range of the second glass frit is 550-650°C. When the softening point is lower than 550°C, the glass powder is fused and deposited prematurely, causing the glass layer between the Si sheet and the Ag electrode to be too thick, increasing the series resistance, and cannot play the role of assisting the sintering of the Ag electrode. When the softening point is higher than 650°C, when the silver powder is sintered, the glass frit has a high viscosity and cannot play a role in sintering.

Preferably, the difference between the softening points of the first glass powder and the second glass powder is 160-260°C.

The amount of the first glass powder should not be less than 1wt%, otherwise it cannot be effectively spread between the silicon wafer and the silver powder, and the ARC layer with a thickness of 70-80nm cannot be completely corroded. The amount of the first glass frit should not be greater than 3wt%, otherwise the glass layer is too thick, increasing the series resistance; or corroding too much, burning through the p/n junction, causing a short circuit. Preferably, the amount of the first glass powder is 1.2-2wt%.

The consumption of the second glass frit should not be less than 1wt%, otherwise it cannot be effectively and evenly dispersed between the silver powders, and the consumption of the second glass frit should not be greater than 5wt%, otherwise the glass frit will form a connection and split the Ag in the Ag electrode. crystals, severely reducing the conductivity of the Ag electrode. Preferably, the amount of the second glass powder is 2.5-3.5wt%.

Preferably, the average particle size of the first glass powder and the second glass powder is 0.1-10 microns. When the particle size is less than 0.1 micron, the powder is agglomerated and it is difficult to disperse in the slurry; when the particle size is greater than 10 micron, it is difficult to be used in the preparation of fine-grid electrodes. More preferably, the average particle size of the first glass powder is 0.3-1.5 micron, and the smaller particle size is conducive to the passage between the first glass powder to pass through the silver powder quickly after melting, and deposit and spread between the Si sheet and the silver powder . More preferably, the average particle size of the second glass powder is 2-6 microns, relatively large particle size is conducive to the contact of single glass powder with more silver powder in the periphery, and helps sintering, but when the particle size is too large, the same In the case of lower dosage, the total number of glass powders is reduced, which is also not conducive to uniform and effective dispersion among Ag powders.

Preferably, the first glass powder contains 65-90wt% Pb compound or Bi compound, or a combination of compounds. More preferred is lead borosilicate glass containing 70-85 wt% PbO. Among them, the compound of Pb or Bi is the main substance used to corrode the ARC film. For example, PbO in the glass frit generates _SiO2 and Pb through a redox reaction with ARC, where _SiO2 dissolves into the glass frit. Bi ³⁺ in glass also has the same effect. The compound content ratio of Pb or Bi in the glass needs to exceed 65wt%, so as to ensure the reaction concentration and continuously and effectively corrode the ARC film with a thickness of 70-80nm. At the same time, more than 65wt% Pb or Bi compounds in the glass can also strongly lower the softening point of the glass, and the softening point of the glass can also be lowered by adding B ₂ O ₃ and a certain amount of alkali metal. Other compounds can also be added to adjust the thermal expansion coefficient, softening point, wettability, viscosity and other properties of the glass.

Preferably, the second glass frit has no strict requirements on components, and SiO ₂ , B ₂ O ₃ , PbO, ZnO, Bi ₂ O ₃ , V ₂ O ₅ and alkali metal compounds can be selected as the main components of the glass. Other compounds can also be added to adjust the thermal expansion coefficient, softening point, wettability, viscosity and other properties of the glass. Preferably, the second glass frit contains at least one of SiO ₂ , B ₂ O ₃ , PbO, ZnO, Bi ₂ O ₃ , V ₂ O ₅ and alkali metal compounds.

Preferably, the shape of the silver powder can be any shape such as flake, granular, colloidal, amorphous, or a combination of powders with various shapes, the average particle size is 0.1-15 microns, and the powder tap density is greater than 3g /cm ³ ; more preferably, granular silver powder with an average particle size of 0.5-2 microns can be selected. The sintering activity of this type of Ag powder is the most suitable, and it can be basically sintered and dense under the condition of rapid sintering higher than 740 °C. If silver powder with a smaller particle size is selected, it is difficult to ensure that the tap density is greater than 3g/cm ³ , and it is easy to agglomerate, resulting in uneven dispersion in the slurry and affecting the fluidity of the slurry.

Preferably, the content of the silver powder in the paste should not be lower than 75wt%, otherwise, even with glass frit to help sintering, it is difficult to sinter densely. More preferably, the silver powder content is 78-85wt%.

According to the electrode silver paste provided by the present invention, the organic component includes a binder, an organic solvent and additives. The binder is ethyl cellulose; the organic solvent is terpineol; the additive is a wetting agent or a rheological aid.

The present invention also provides a method for preparing the positive electrode silver paste, which includes mixing and grinding silver powder, first glass powder, second glass powder and organic components.

The method for preparing the front electrode of a solar cell according to the specific embodiment of the present invention comprises the following steps: printing the front electrode paste according to the specific embodiment of the present invention on the light-receiving surface of the semiconductor substrate by screen printing, drying, and then rapid sintering Forming the front electrode of the solar cell; the peak temperature of the rapid sintering process is 755-765° C., and the peak temperature time is 1-3 seconds.

The rapid sintering method of the front electrode is a mature metallization process for the large-scale industrial production of crystalline silicon solar cells today. It generally includes four stages: the combustion of organic matter stage, the heating stage, the peak temperature range, and the cooling stage.

The stage of burning organic matter is generally at 300°C. If the temperature is too high, the contact resistance between metal and semiconductor will be too large. If the temperature is too low, the organic matter will not be completely volatilized, which will also cause the same problem.

There are two kinds of heating stages: rapid heating and slow heating. The process of rapid temperature rise is generally to keep the temperature at about 350°C in the first 80 seconds of the sintering process, and then rapidly increase the temperature to 780°C within a few seconds (3-5 seconds) at about 80 seconds. The slow heating process generally keeps the temperature at about 300°C in the first 40 seconds of the sintering process, and then raises the temperature to above 750°C within about 50 seconds after about 40 seconds. The specific heating rate is controlled by the sintering furnace used.

The peak temperature range is a critical process, and special attention should be paid to the setting of the peak temperature. The peak temperature determines the concentration of metal ions in the silver-aluminum alloy and aluminum-silicon alloy during the sintering process. Both the series resistance and the fill factor of solar cells have a great influence. According to the method for preparing the front electrode of a solar cell according to the specific embodiment of the present invention, the peak temperature of the sintering process is 750-790° C., and the peak temperature time is 1-3 seconds. The bonding of the front electrode obtained in this way to the semiconductor crystalline silicon substrate The strength is improved, the thickness of the electrode is uniform, and there is no disconnection or material drop, and the filling factor, series resistance, and photoelectric conversion efficiency of the battery are all improved.

The cooling process generally requires constant speed and continuous, without large temperature gradient changes. However, an annealing process may also be added after the peak interval as required. This process can improve the over-sintering caused by too high peak temperature.

Other processes for preparing crystalline silicon solar cells, such as texturing, diffusion junction, removal of phospho-silicate glass, removal of PN junction at the edge of silicon wafer, deposition of anti-reflection film, screen printing, etc. are not particularly limited, and can all be used in this field. well-known process. For example, use a sodium hydroxide solution with a concentration of about ₁ % and a temperature of 70-85°C to chemically etch the polycrystalline silicon surface; Carry out chemical etching for texturing; use liquid POCl ₃ as P source (or use P ₂ O ₅ +H ₂ O as P source) to expand P junction; plasma enhanced chemical vapor deposition (PECVD) or glow discharge method to deposit nitride Silicon anti-reflection coating. The above-mentioned processes have little to do with the inventive points of the present invention, and are all prior art, so they will not be repeated here.

The present invention will be further described in detail below in combination with technical examples.

Example 1

1. Preparation of electrode silver paste

Silver powder 79%, average particle size 0.8 micron; first glass frit powder 1.5% PbO-B ₂ O ₃ -SiO ₂ (PbO: 85wt%) average particle size 1.5 micron, softening point 360°C; second glass frit Powder 3.5%, B ₂ O ₃ -ZnO-V ₂ O ₅ , average particle size 2.5 microns, softening point 620°C; pine oil alcohol 12%, ethyl cellulose 2%, wetting and dispersing agent 2%.

The above materials were mixed and ground in a three-roll mill, and the fineness reached 13 microns to obtain electrode silver paste A1.

2. Preparation of polycrystalline silicon solar cells

First, the surface texture of three P-type polysilicon wafers with an area of 156 mm × 156 mm was carried out: the polysilicon wafers were soaked in a solution of 20 wt % and 10 wt % of NaOH and ethanol at 75 ° C for 40 min. Take out the polysilicon chip, wash it with deionized water 10 times, to wash off the remaining texturing liquid on the surface of the silicon chip, and then dry it.

Then use liquid POCl ₃ as a phosphorus source to diffuse phosphorus on the surface of the textured polysilicon wafer to form a layer of N-type silicon on one surface of the P-type polysilicon, thereby forming a PN junction. The emitter junction square resistance of the polysilicon solar cell after phosphorus expansion is usually 65Ω per square, and the thickness of the polysilicon wafer is 180 μm. Afterwards, it is treated with dephosphorous silicon glass, edge passivation, and PECVD anti-reflection coating.

The backside of the polysilicon is coated with commercial ferro53-102 and 3347 backside electrode paste to form a negative electrode.

The screen printing machine (Dongguan Youyin screen printing machinery factory, UP-S7090) that is 280-320 with screen mesh subsequently prints the electrode silver paste A1 on the polysilicon light-receiving surface after the phosphorus-expanding system is knotted, every A piece of polysilicon consumes 10.18g of electrode silver paste. Dry at 250°C for 5 minutes, and then start sintering at 300°C in a 12-meter-long tunnel furnace. The sintering termination temperatures are 750°C, 770°C, and 790°C. Cool down to 100°C at a cooling rate of 164°C/S to form grid electrodes on the light-receiving surface. The peak temperature of sintering is 750℃, 770℃ and 790℃, and the peak temperature time is 2s. At three sintering temperatures, polycrystalline silicon solar cells B1 , C1 and D1 are respectively obtained.

Example 2

Silver powder 83.5%, average particle size 1.2 microns; first glass frit powder 2.5% Bi ₂ O ₃ -B ₂ O ₃ -SiO ₂ -K ₂ O (Bi ₂ O ₃ : 82wt%) average particle size 0.6 microns, Softening point 420°C; second glass frit powder 2%, PbO-ZnO-SiO ₂ , average particle size 6 microns, softening point 580°C; terpineol 9.5%, ethyl cellulose 1.5%, wetting and dispersing agent 1 %.

The above materials were mixed and ground in a three-roller mill to a fineness of 15 microns to obtain electrode silver paste A2.

Polycrystalline silicon solar cells B2, C2 and D2 were prepared according to the method of Example 1.

Example 3

Silver powder 83.5%, average particle size 1.2 microns; first glass frit powder 2% PbO-B ₂ O ₃ -SiO ₂ -ZnO (PbO: 78wt%) average particle size 0.8 microns, softening point 380°C; second Glass frit powder 2.5%, PbO-ZnO-B ₂ O ₃ , average particle size 1.5 microns, softening point 550°C; terpineol 8.8%, ethyl cellulose 1.5%, wetting and dispersing agent 1.7%.

The above-mentioned materials were mixed and ground in a three-roll mill, and the fineness reached 14 microns to obtain electrode silver paste A3.

Polycrystalline silicon solar cells B3, C3 and D3 were prepared according to the method of Example 1.

Example 4

Silver powder 75%, average particle size 0.1 micron; first glass frit powder 3% PbO-B ₂ O ₃ -SiO ₂ -ZnO (PbO: 78wt%) average particle size 0.3 micron, softening point 350°C; second Glass frit powder 5%, PbO-ZnO-B ₂ O ₃ , average particle size 0.1 micron, softening point 600°C; terpineol 11%, ethyl cellulose 4%, wetting and dispersing agent 2%.

The above materials were mixed and ground in a three-roller mill, and the fineness reached 13 microns to obtain electrode silver paste A4.

Polycrystalline silicon solar cells B4, C4 and D4 were prepared according to the method of Example 1.

Example 5

Silver powder 90%, average particle size 2 microns; first glass frit powder 1% PbO-B ₂ O ₃ -SiO ₂ -ZnO (PbO: 78wt%) average particle size 0.1 microns, softening point 550°C; second Glass frit powder 1%, PbO-ZnO-B ₂ O ₃ , average particle size 2 microns, softening point 620°C; terpineol 7%, ethyl cellulose 1%.

The above materials were mixed and ground in a three-roller mill to a fineness of 15 microns to obtain electrode silver paste A5.

Polycrystalline silicon solar cells B5, C5 and D5 were prepared according to the method of Example 1.

Example 6

Silver powder 85%, average particle size 15 microns; first glass frit powder 1.2% PbO-B ₂ O ₃ -SiO ₂ -ZnO (PbO: 78wt%) average particle size 10 microns, softening point 400°C; second Glass frit powder 4%, PbO-ZnO-B ₂ O ₃ , average particle size 10 microns, softening point 650°C; terpineol 7%, ethyl cellulose 2.8%.

The above materials were mixed and ground in a three-roll mill until the fineness reached 12 microns to obtain electrode silver paste A6.

Polycrystalline silicon solar cells B6, C6 and D6 were prepared according to the method of Example 1.

Comparative example 1

Commercially available electrode paste (Ferro, 33-462 front silver paste) CA1 was used to prepare polycrystalline silicon solar cells CB1, CC1 and CD1 according to the method of Example 1.

Comparative example 2

Silver powder 83.5%, average particle size 1.2 microns; glass frit powder 4.5% Bi ₂ O ₃ -B ₂ O ₃ -SiO ₂ -K ₂ O (Bi ₂ O ₃ : 82wt%) average particle size 0.6 microns, softening point 420 ℃; Terpineol 9.5%, ethyl cellulose 1.5%, wetting and dispersing agent 1%.

The above materials were mixed and ground in a three-roll mill, and the fineness reached 15 microns to obtain electrode silver paste CA2.

Polycrystalline silicon solar cells CB2, CC2 and CD2 were prepared according to the method of Example 1.

Comparative example 3

Silver powder 83.5%, average particle size 1.2 microns; glass frit powder 4.5%, PbO-ZnO-B ₂ O ₃ , average particle size 1.5 microns, softening point 550°C; terpineol 8.8%, ethyl cellulose 1.5%, Wetting and dispersing agent 1.7%.

The above materials were mixed and ground in a three-roller mill to a fineness of 14 microns to obtain electrode silver paste CA3.

Polycrystalline silicon solar cells CB3, CC3 and CD3 were prepared according to the method of Example 1.

Comparative example 4

Silver powder 83.5%, average particle size 1.2 microns; glass frit powder is 2.5% Bi ₂ O ₃ -B ₂ O ₃ -SiO ₂ -K ₂ O (Bi ₂ O ₃ : 82wt%) and 2% PbO-B ₂ O ₃ -SiO ₂ -ZnO (PbO: 78wt%), the average particle size is 0.6 microns, the softening point is 420 ° C, 380 ° C; 9.5% terpineol, 1.5% ethyl cellulose, wetting and dispersing agent 1 %.

The above materials were mixed and ground in a three-roller mill to a fineness of 14 microns to obtain electrode silver paste CA4.

Polycrystalline silicon solar cells CB4, CC4 and CD4 were prepared according to the method of Example 1.

Comparative example 5

Silver powder 83.5%, average particle size 1.2 microns; glass frit powders are 2.5% PbO-ZnO-B ₂ O ₃ and 2% PbO-ZnO-SiO ₂ , the average particle size is 1.5 microns, and the softening points are 550°C and 580°C; 8.8% terpineol, 1.5% ethyl cellulose, 1.7% wetting and dispersing agent.

The above materials were mixed and ground in a three-roller mill, and the fineness reached 14 microns to obtain electrode silver paste CA5.

Polycrystalline silicon solar cells CB5, CC5 and CD5 were prepared according to the method of Example 1.

Test Method and Results

Fill factor, series resistance, photoelectric conversion efficiency of solar cells

The above-mentioned properties of the polycrystalline silicon solar cells obtained by the methods of the examples and the comparative examples were tested under standard test conditions (STC) with a special testing instrument for solar cells (Shanghai Juna Technology Co., Ltd., NELC-140A). The test results are shown in Table 1 below for the sintering temperature of 750°C, shown in Table 2 for the sintering temperature of 770°C, and shown in Table 3 for the sintering temperature of 79°C. Standard test conditions (STC) are as follows: light intensity: 1000W/m ² ; spectrum: AM1.5; temperature: 25°C.

Table 1

Photoelectric conversion rate% Series resistance mΩ Parallel resistance Ω B1 16.35 3.6 >100 B2 16.4 3.45 >100 B3 16.5 3.3 >100 B4 16.3 3.8 >100 B5 15.9 6.2 >100 B6 16.3 3.7 >100 CB1 16.05 4.3 >100 CB2 16.1 4.0 >100 CB3 16.05 4.4 >100 CB4 16.3 3.8 >100 CB5 16.0 4.6 >100

Table 2

Photoelectric conversion rate% Series resistance mΩ Parallel resistance Ω C1 16.42 3.4 >100 C2 16.5 3.2 88 C3 16.5 3.2 91 C4 16.4 3.5 76 C5 16.1 3.9 >100 C6 16.5 3.3 80 CC1 16.4 3.5 86 CC2 16.4 3.4 82 CC3 16.35 3.6 95 CC4 16.5 3.1 89 CC5 16.3 3.6 >100

table 3

Photoelectric conversion rate% Series resistance mΩ Parallel resistance Ω D1 16.6 3.2 95 D2 16.45 3.4 89 D3 16.4 3.45 90 D4 16.3 3.7 82 D5 16.4 3.4 92 D6 16.3 3.6 83 CD1 15.7 5.1 31 CD2 15.8 5.3 28 CD3 16.0 4.8 34 CD4 15.8 5.2 29 CD5 16.2 3.9 75

It can be seen from the experimental results that the present invention can obtain low series resistance and high parallel resistance under different sintering temperature conditions of 750-790° C. The photoelectric conversion efficiency of the sheet is above 16.0%, but the solar cell of the comparative example can only meet a narrow sintering temperature range, and the photoelectric conversion efficiency is very low if the temperature exceeds this range.

Claims (11)

1. a crystal silicon solar energy battery front electrode silver slurry, is characterized in that, described silver slurry comprisesSilver powder, the first glass dust, the second glass dust and organic component; Taking the gross weight of silver slurry as benchmark, described inThe content of silver powder is 75-90wt%, and the content of described the first glass dust is 1-3wt%, described the second glassThe content of powder is 1-5wt%, and the content of described organic component is 6-25wt%; Described the first glass dust softChange point for 350-550 DEG C, the softening point of described the second glass dust is 550-650 DEG C, and the first glass dustAnd differ at least 70 DEG C between the softening point of the second glass dust.

2. electrode silver plasm according to claim 1, is characterized in that, described the first glass dust withBetween the softening point of the second glass dust, differ 160-260 DEG C.

3. electrode silver plasm according to claim 1, is characterized in that, the content of described silver powder is78-85wt%, the content of described the first glass dust is 1.2-2wt%, the content of described the second glass dust is2.5-3.5wt%, the content of described organic component is 8-18wt%.

4. electrode silver plasm according to claim 1, is characterized in that, described the first glass dustAverage grain diameter is 0.1-10 micron, and the average grain diameter of described the second glass dust is 0.1-10 micron.

5. electrode silver plasm according to claim 4, is characterized in that, described the first glass dustAverage grain diameter is 0.3-1.5 micron.

6. electrode silver plasm according to claim 4, is characterized in that, described the second glass dustAverage grain diameter is 2-6 micron.

7. electrode silver plasm according to claim 1, is characterized in that, described the first glass dust containsThere are the compound of Pb or the compound of Bi of 65-90wt%.

8. electrode silver plasm according to claim 7, is characterized in that, described the first glass dust isThe lead borosilicate glass that contains 70-85wt%PbO.

9. electrode silver plasm according to claim 1, is characterized in that, described the second glass dust containsThere is SiO₂、B₂O₃、PbO、ZnO、Bi₂O₃、V₂O₅And at least one in alkali metal compound.

10. electrode silver plasm according to claim 1, is characterized in that, the average particle of described silver powderDegree is 0.1-15 micron.

The preparation method of 11. 1 kinds of front electrode silver slurry claimed in claim 1, is characterized in that, shouldMethod comprises mixes silver powder, the first glass dust, the second glass dust and organic component grind.