KR20190119124A - Glass frit, glass frit manufacturing method and aluminum paste - Google Patents

Abstract

(Purpose) The present invention relates to a glass frit, a glass frit manufacturing method and an aluminum paste used in an aluminum paste for forming an aluminum electrode such as the back surface of a solar cell, and do not include metals such as iron, copper, nickel, and chromium. At the same time, an object of the present invention is to realize the production of a glass frit containing only vanadium and barium, whose main components are melted at low temperatures necessary for manufacturing solar cells and the like.
Composition: Vanadium V ₂ O ₅ from 55 to 80 mol% and barium BaO from 15 to 30 mol%, or Vanadium V ₂ O ₅ from 10 to 55 mol% and barium BaO from 10 to 40 mol% And heated to produce a molten glass, which is prepared by pulverizing rapidly cooled debris and melted at 650 ° C. or lower.

Description

Glass frit, glass frit manufacturing method and aluminum paste

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass frit, a method for producing a glass frit, and an aluminum paste used in an aluminum paste for forming an aluminum electrode such as a back surface of a solar cell.

Background Art Conventionally, solar cells, which are one of renewable energy utilization, have been developed based on semiconductor technology, which is a major player of the 20th century. It is an important development at the Earth level that influences human survival. The development task is progressing while coping not only with the efficiency of converting sunlight into electrical energy, but also with the task of reducing manufacturing cost and pollution-free. In order to implement these measures, it is particularly important to reduce or eliminate the amount of silver (Ag) and lead (Pb) used in the electrodes.

For example, on the back surface of the silicon substrate (p type) constituting the solar cell, aluminum paste is applied and sintered on the entire surface to form an aluminum electrode (p +), and a lead wire is soldered thereto. Was doing.

However, in the case where the lead wire was directly soldered to the aluminum electrode, the tensile strength was weak, a plurality of holes were drilled in the aluminum electrode, and silver paste was applied and sintered thereon, and the lead wire was soldered thereto.

Since aluminum electrodes formed by coating and sintering aluminum pastes on the back side of solar cells are exposed to excessive conditions for a long time, the presence of metals such as iron, copper, nickel, and chromium in glass frits constituting the aluminum paste may adversely affect them. The possibility of deterioration of the performance of solar cells has been suggested.

Therefore, the appearance of the new glass frit which does not contain the material which adversely affects these irons etc. in the glass frit which comprises aluminum paste etc. and melts at low temperature is expected.

The present inventors have made it possible to produce glass frits whose main components are vanadium and barium, which do not contain metals such as iron, copper, nickel, and chromium, and which are melted at low temperatures necessary for the production of solar cells and the like.

Therefore, the present invention is a glass frit coated and sintered to a substrate to be incorporated into a conductive paste for forming a conductive electrode, wherein vanadium V ₂ O ₅ is 55 to 80 mol% and barium BaO is 15 to 30 mol% as the main material. And heated to produce a molten glass, which was prepared by pulverizing rapidly cooled debris and a glass frit melted at 650 ° C. or lower.

At this time, iron, copper, nickel, and chromium are not included.

Further, as an additive, one or more of aluminum Al ₂ O ₃ from 0 to 15 mol%, boron B ₂ O ₃ from 0 to 10 mol%, and silicon SiO ₂ from 0 to 7 mol% are mixed with the main material and heated to melt the glass. To create a.

In addition, an aluminum paste is used as the conductive paste.

In addition, a conductive electrode is formed by coating and sintering the substrate, and a conductive aluminum electrode is formed by coating and sintering the substrate of the solar cell.

In addition, in a glass frit coated and sintered to a substrate and mixed in a conductive paste for forming a conductive electrode, the molten glass is heated with 10 to 55 mol% of vanadium V ₂ O ₅ and 10 to 40 mol% of barium BaO as a main material. The glass frit was prepared by pulverizing the rapidly cooled debris and melting at 650 ° C. or lower.

In addition, as an additive, aluminum Al ₂ O ₃ from 1 to 10 mol% and boron B ₂ O ₃ from 1 to 20 mol% are mixed in the main material and heated to produce the molten glass.

Further, as an additive, phosphorus P ₂ O ₅ is mixed in an amount of 5 to 20 mol% and calcium CaO is 5 to 20 mol% in a main material and heated to produce the molten glass.

In addition, calcium CaO added together with phosphorus P ₂ O _{5 is used} as one or more compounds of phosphorus and alkaline earth metals.

Furthermore, as said calcium CaO added together with phosphorus P ₂ O ₅ , tricalcium phosphate Ca ₃ (PO ₄ ) ₂ or calcium metaphosphate Ca (PO ₃ ) ₂ , which is one or more compounds of phosphorus and alkaline earth metals. I'm supposed to.

The present invention is a glass frit whose main materials are vanadium and barium, which do not contain metals such as iron, copper, nickel, and chromium and are melted at 650 ° C. or lower, which is a low temperature necessary for manufacturing solar cells as described above. Could be manufactured. These have the following characteristics.

(1) The glass frit was able to eliminate the content of substances that adversely affect the solar cells such as iron, copper, nickel, and chromium under excessively harsh conditions. As a result, it was possible to eliminate the deterioration of the life due to the inclusion of iron in the solar cell.

(2) The low melting point 650 ° C. or lower necessary for use as an aluminum paste could be realized. As a result, sintering is possible at a low melting point, thereby realizing a glass frit of aluminum paste that can be used to form an aluminum electrode on the rear surface of a solar cell.

(3) By the structure of vanadium and barium, the curvature of the board | substrate of the solar cell at the time of aluminum paste sintering was eliminated.

I / V characteristics and adhesiveness could be improved by adding P ₂ O ₅ (4) and an alkaline earth metal (for example, calcium CaO).

(5) The vitrification was facilitated by adding a predetermined mixture of aluminum Al ₂ O ₃ and boron B ₂ O ₃ .

1 is a manufacturing flow chart 1 of the ABS glass of the present invention.
Fig. 2 is an example (1) of a production sample of the ABS glass of the present invention.
3 is an example (1) of an aluminum paste frit for a solar cell of the present invention.
4 is an explanatory diagram (1) of an example of the upper limit and the lower limit of each component range of the ABS glass of the present invention.
5 is an explanatory diagram (1) of the aluminum electrode firing frit for solar cells of the present invention.
6 is an example of an overview photograph of the ABS glass of the present invention.
Fig. 7 is a manufacturing flow chart 2 of the ABS glass of the present invention.
Fig. 8 is an example (2) of a production sample of the ABS glass of the present invention.
9 is an example (2) of an aluminum paste frit for a solar cell of the present invention.
10 is an explanatory diagram (2) of an example of the upper limit and the lower limit of each component range of the ABS glass of the present invention.
11 is an explanatory diagram (2) of the aluminum electrode firing frit for solar cells of the present invention.
12 is an explanatory diagram of the aluminum paste of the present invention.
Fig. 13 is a manufacturing flowchart of the aluminum paste of the present invention.
14 is a firing flow chart of the aluminum paste of the present invention.

Example 1

Fig. 1 shows a manufacturing flow chart 1 of ABS glass (glass for art beam solar cell) of the present invention.

In Fig. 1, S1 is melted (900 deg. C to 1200 deg. C) in combination with a glass raw material (put in a place where the temperature of the electric furnace is raised and left for 1 hour). When this raises the temperature of an electric furnace to the optimal temperature determined by the experiment of 900 degreeC-1200 degreeC, the raw material of the combined glass is put in a crucible, it melt | dissolves, and it is left for 1 hour. In addition, the raw material placed in the crucible may be melted by raising to a specified temperature in an electric furnace and left for 1 hour. The raw material of glass is as showing in FIG. 2 mentioned later, for example in an experiment.

Sample No. 1: Vanadium V ₂ O ₅ 77.78 mol%

Barium BaO 22.22 mol%

Sample No. 2: Vanadium V ₂ O ₅ 65 mol%

Barium BaO ₂ 25 mol%

Aluminum Al ₂ O ₃ 5 mol%

Boron B ₂ O ₃ 3 mol%

Silicon SiO ₂ 2mol%

Sample No. 3: Vanadium V ₂ O ₅ 60 mol%

Barium BaO ₂ 25 mol%

Aluminum Al ₂ O ₃ 6 mol%

Boron B ₂ O ₃ 5 mol%

Silicon SiO ₂ 4mol%

S2 manufactures glass fragments (3-5 mm). This is produced while flowing the molten glass produced by S1 into the chilled metal roller as described below. In other words, molten glass is introduced between the water-cooled and rotating metal rollers and rapidly cooled to produce glass fragments of about 3 to 5 mm.

S3 is coarsely pulverized (powder 2-3 mm) and pulverized (-50 mu m). This coarsely pulverizes the glass fragments of 3 to 5 mm which are rapidly cooled in S2 to form a powder of 2 to 3 mm, and further grinds them to a powder of about 50 µm.

S4 performs fine grinding (2-3 micrometers) (jet-mill apparatus). This is pulverized further to the powder of -50 micrometers of S3 using a jet mill apparatus, and it is set as the powder (glass powder, glass frit) about 2-3 micrometers.

S5 completes the frit of the sintering aid for solar cell aluminum electrodes.

As mentioned above, the raw materials are raised to a specified temperature (900 ° C to 1200 ° C) to melt them to form a molten glass, and the molten glass is rapidly cooled to produce glass fragments (3 to 5 mm), which are coarsely pulverized, pulverized and pulverized. The glass frit (glass powder) of about 2-3 micrometers was produced (refer FIG. 6).

2 shows an example (1) of a production sample of the ABS glass of the present invention.

2 (a) shows sample No. 1, sample No. 2, and sample No. 3. FIG. These represent the names given to the samples.

2 (b) shows mol% of the raw material of each sample. For example, sample No. 1

Sample No. 1: Vanadium V ₂ O ₅ 77.78 mol%

Barium BaO 22.22 mol%

Made of raw materials. Other samples also consist of the raw materials shown.

In addition, the "range" described at the edge of the right side showed the range of each raw material which can produce a favorable glass frit, and can produce favorable glass frit when it exists in the following range shown.

Vanadium V ₂ O ₅ 55-80 mol%

Barium BaO 15-30 mol%

Zinc ZnO-

Nickel NiO 0 mol%

Aluminum Al ₂ O ₃ 0-10 mol%

Boron B ₂ O ₃ 0-7 mol%

Silicon SiO ₂ 0-7 mol%

Iron Fe ₂ O ₃ 0 mol%

Fig. 2C shows the combination ratio g. This shows an example of g when each raw material is combined in the ratio of mol% of FIG.2 (b).

2 (d) shows an example of the characteristics of the glass frit of the present invention.

It was observed that the molten glass did not crystallize even if it flowed out on the metal plate.

It was observed that neither sample No. 2 nor sample No. 3 crystallized.

Softening observation: When the glass frit prepared in Fig. 1 is placed in the crucible and the temperature is raised,

Sample No. 1 began to melt at 570 ° C. and melted completely at 595 ° C.

Sample No. 2 and Sample No. 3 both started to melt at 572 ° C and completely melted at 587 ° C.

Fig. 2E shows an example of the transition temperature of the glass. The values shown are obtained for each transition temperature as shown.

Here, the crystal melting temperature is set to Sample No. 1. Sample No.2. In sample No. 3, it turned out that all of 515 degreeC, 525 degreeC, and 524 degreeC are 600 degrees C or less, and the target 650 degrees C or less can be implement | achieved.

Fig. 3 shows an example (component molar ratio) 1 of an aluminum paste frit for a solar cell of the present invention. This is the sample No. 1 of FIGS. 2 (a) and (b) of the experimental example described above. Sample No.2. The mole% portion of sample No. 3 was taken out and summarized for easy understanding.

Sample No.1 is a vanadium V ₂ O ₅ is as 77.58 mol%, is in the range of 55~80 mol% range. Barium BaO is 22.22 mol% and exists in the range of 15-30 mol%.

Sample No. 2 and Sample No. 3 are also in the range as shown.

Sample No.1 or above. Sample No.2. With respect to sample No. 3, various characteristics described in Figs. 2 (d) and (e) described above can be observed and measured, and in particular, the melting temperature can achieve 650 ° C. or lower, so that the aluminum paste of the solar cell can be obtained. It turned out that it can be used as the glass frit mixed in. And this glass frit does not contain iron, copper, nickel, and chromium, and does not deteriorate the characteristic of a solar cell even in long term use.

4 shows an explanatory diagram (1) of an example of the upper limit and the lower limit of each component range of the ABS glass of the present invention.

4 (a) shows the description of an example of the upper limit and the lower limit of vanadium V ₂ O ₅ (55 to 80 mol%).

· When the vanadium V ₂ O ₅ less than the lower limit (55 mol%), are not fulfill the skeleton of glass.

, Vanadium is greater than or equal to V ₂ O ₅ is the upper limit (80 mol%), it is difficult to adjust the mechanical strength. Water resistance deteriorates.

Fig. 4B shows an explanation of an example of the upper limit and the lower limit of barium BaO (actually BaCO ₃ is added to the raw material and CO ₂ is released to form BaO at the time of heating melting).

When barium BaO (BaCO ₃ ) is below the lower limit (15 mol%), homogeneous vitrification becomes difficult.

When the barium BaO (BaCO ₃ ) is above the upper limit (30 mol%), the mechanical strength deteriorates.

FIG. 4C shows an explanation of other additives (for example, three kinds of additives of FIG. 4D).

The following additives play a role of preventing the aluminum material (trivalent) from increasing or increasing the formation of the P-type function with respect to the silicon (tetravalent). In some cases, there may be no additives.

4 (d) shows an example of an additive.

Aluminum Al ₂ O ₃ (0-10 mol%):

Boron B ₂ O ₃ (0-7 mol%):

Silicon SiO ₂ (0-7 mol%):

It is important to have a good balance of the blending ratio of these three components. Otherwise, uniformity will not be maintained and crystals will precipitate. Any two components or one component or none may be used. However, in order to maintain the water resistance, it is preferable to add silicon SiO ₂ .

Fig. 5 shows an explanatory diagram (1) of the aluminum electrode firing frit for solar cells of the present invention. This is the problem (requirement) (1), (2), (3) which is required for the glass frit to be mixed in the aluminum paste when the aluminum paste is coated and sintered on the back surface of the solar cell to form the aluminum electrode. Table 1 shows the means to be solved by the present invention.

Fig. 5A shows the problem "(1) low melting point" and the solution of the present invention. In the present invention, as described above, vanadium and barium are mainly used to realize 600 ° C. or less. This is because the sintering temperature is determined at the midpoint between the melting point of aluminum (660 ° C) and the melting point of the frit. In the present invention, the melting point of the glass frit is defined as 650 ° C or less, and in experiments, 600 ° C or less can be realized (Fig. The crystal melting temperatures of 515 ° C, 525 ° C, and 524 ° C in 2 (e) were realized at 600 ° C or lower).

FIG. 5 (b) shows the problem "(2) Component structure which does not affect the lifetime of a silicon solar cell" and the solution means of this invention. In the present invention, iron, copper, nickel, chromium and the like are not included as described above. The basis is a combination of vanadium, barium, silicon, aluminum and boron. Here, silicon, aluminum, and boron are the contact materials of the back side aluminum.

As described above, since the glass frit is made of a material that does not contain iron, copper, nickel, chromium, or the like, which adversely affects the solar cell under prolonged severe use conditions, these adverse effects can be avoided.

Fig. 5C shows the problem "(3) the silicon substrate is not bent at the time of sintering" and the solution means of the present invention. In the present invention, the warpage of the substrate during sintering of aluminum is eliminated by the components of vanadium and barium as described above.

Fig. 6 shows an example of an overview photograph of the ABS glass of the present invention. This shows an example of an overview photograph of the ABS glass produced in the process of FIG. 1 described above.

Fig. 6A shows an example of the photograph of the ABS glass. This shows an example of an overview photograph when an experiment for experimentally producing the glass fragment (referred to as ABS glass) of S2 described above in Fig. 1 has been conducted.

Fig. 6B shows an example of an overview photograph of ABS glass that has been crushed (2 to 3 mm). ABS glass is crushed into glass pieces of about 2-3 mm.

Fig. 6C shows an example of an overview picture of the crushed ABS glass (-50 mu m). ABS glass is pulverized about -50 micrometers. Furthermore, it is pulverized about 2-3 micrometers by the jet mill apparatus, and glass frit is completed.

Further, for producing an aluminum paste incorporating a glass frit, for example, (1) aluminum fine powder, (2) glass frit (fine powder) of the present invention, (3) organic material, (4) organic solvent, (5) It prepares by putting in a container by order of resin (or you may change order), and stirring well.

The produced aluminum paste is screen printed, solvent removed, and sintered to form a desired aluminum pattern on the back surface of the substrate of the solar cell to form an aluminum electrode.

Fig. 7 shows a production flow chart 2 of the ABS glass (glass for art beam solar cell) of the present invention.

In Fig. 7, S11 is melted (900 deg. C to 1200 deg. C) in combination with a glass raw material (put in a place where the temperature of the electric furnace is raised and left for 1 hour). When this raises the temperature of an electric furnace to the optimal temperature determined by the experiment of 900 degreeC-1200 degreeC, the raw material of the combined glass is put in a crucible, it melt | dissolves, and it is left for 1 hour. The raw material placed in the crucible may be melted by raising to a specified temperature in an electric furnace and left for 1 hour. The raw material of glass is as showing in FIG. 8 and FIG. 9 mentioned later, for example in an experiment.

(Unit is mole%)

S12 manufactures glass fragments (3-5 mm). This is produced while injecting the molten glass produced in S11 into the chilled metal roller as described below. In other words, the molten glass is introduced between the rotating metal rollers, which are water-cooled, and rapidly cooled to produce glass fragments of about 3 to 5 mm.

S13 is coarsely pulverized (powder 2-3 mm) and pulverized (-50 mu m). This coarsely pulverizes the glass fragments of 3 to 5 mm which are rapidly cooled in S12 to obtain a powder of 2 to 3 mm, and further grinds them to a powder of about 50 µm.

S14 performs fine grinding (2-3 micrometers) (jet mill apparatus). This is pulverized further to the powder of -50 micrometers of S13 using a jet mill apparatus, and it is set as the powder (glass powder, glass frit) about 2-3 micrometers.

S15 completes the frit of the sintering aid for solar cell aluminum electrodes.

As mentioned above, the raw materials are raised to a specified temperature (900 ° C to 1200 ° C) to melt them to form a molten glass, and the molten glass is rapidly cooled to produce glass fragments (3 to 5 mm), which are coarsely pulverized, pulverized and pulverized. To produce a glass frit (glass powder) of about 2-3 μm.

Fig. 8 shows an example (2) of a production sample of the ABS glass of the present invention.

In Fig. 8, "sample 11" in (a) represents sample 11. These show the name given to the sample 11, and the lower end shows the raw material (material) name.

In FIG. 8, the "molar ratio%" in the "molar ratio% (range)" of (b) shows mol% of the raw material of a sample.

For example, sample 11

Vanadium V ₂ O ₅ 25 mol%

Barium BaO 28 mol%

Boron B ₂ O ₃ 15 mol%

Aluminum Al ₂ O ₃ 2 mol%

13 mol% of phosphorus P ₂ O ₅

Calcium CaO 13mol%

Zinc ZnO 4 mol%

Tungsten WO ₃ 0 mol%

Antimony Sb ₂ O ₃ 0 mol%

Made of raw materials.

In addition, "range" in the "molar ratio% (range)" of FIG. 8B shows the range of each raw material which can produce a favorable glass frit, and when it exists in the following range shown, a favorable glass frit can be manufactured. Can be.

Vanadium V ₂ O ₅ 10-55 mol%

Barium BaO 10-40 mol%

Boron B ₂ O ₃ 1-20 mol%

Aluminum Al ₂ O ₃ 1-10 mol%

Phosphorus P ₂ O ₅ 5-20 mol%

Calcium CaO 5-20 mol%

Zinc ZnO 1-10 mol%

Tungsten WO ₃ 0 mol%

Antimony Sb ₂ O ₃ 0 mol%

In Fig. 8, (c) represents the mass g. This shows an example of g when each raw material is combined in the ratio of mol% of FIG. 8 (b).

In FIG. 8, (d) shows the characteristic example of the glass frit of this invention.

The condition in the crucible was good. This was in good condition when the raw material was placed in a crucible and dissolved.

The fact that the surface of the flowing state is "quite cloudy" indicates that the surface of the melt in a state in which the melt dissolved in the crucible has flowed into the rapid cooling device was in a "quite cloudy" state.

Softening observation shows "500 degreeC: particle | grains show circular shape. 600 ° C .: Particles stick together ”means that when the glass frit prepared in Fig. 7 is placed in a crucible and the temperature is raised, the particles are circular around 500 ° C. and the particles are stuck together at 600 ° C. Indicates.

The surface after cooling is "brown." It is raised to 650 degreeC, and it peels off from a crucible "and shows that the surface of the state after cooling of the melt is" brown ", and when melt | dissolution which put in the crucible is raised to 650 degreeC, the melt melts easily from the crucible and fell.

In Fig. 8, in the DTA of (e), the peak of the DTA measurement (each temperature measurement such as transition point, softening point, crystallization, crystal melting, etc.) did not appear.

9 shows an example (component molar ratio) 2 of an aluminum paste frit for a solar cell of the present invention. This is a sample 11 of FIG. 8, which is the above-described experimental example, and mole percent of other samples 12 and 13 other than those shown in FIG. 8, which are summarized for easy understanding and added with the results (adhesiveness, I / V characteristics). will be.

Here, aluminum Al ₂ O ₃ is apt to be when the glass screen was added.

In addition, the P ₂ O _5, the glass is difficult to upset also added anyway. Phosphorus was added as a compound of an alkaline earth metal (for example, calcium), and dissolved in the melt of the first main material (main skeleton composed of barium V ₂ O ₅ and vanadium BaO) to allow vitrification. For example, it is added as a hydrate (Ca (H ₂ PO ₄ ) ₂ .H ₂ O) of calcium dihydrogen phosphate (or calcium phosphate).

The above-described samples 11, 12, and 13 were observed and measured for various properties described in Figs. 8 (d) and (e), and the melting temperature of 650 ° C or lower was achieved. The adhesiveness described above (adhesiveness after coating, drying and sintering aluminum paste of solar cell using glass frit on the backside of solar cell substrate, for example), and evaluated I / V characteristics of solar cell, For example, about twice as good) was obtained in Sample 11. And this glass frit does not contain iron, copper, nickel and chromium, so it does not deteriorate the characteristics of the solar cell even after long-term use.

FIG. 10: shows explanatory drawing (2) of the example of the upper limit and the lower limit of each component range of the ABS glass of this invention.

10 (a) shows the description of an example of the upper limit and the lower limit of vanadium V ₂ O ₅ (10 to ₅₅ mol%).

· When the vanadium V ₂ O ₅ less than the lower limit (10 mol%), are not fulfill the skeleton of glass.

, Vanadium is greater than or equal to V ₂ O ₅ is the upper limit (55 mol%), it is difficult to adjust the mechanical strength. Water resistance deteriorates.

Here, the range of vanadium V ₂ O ₅ (10 to 55 mol%) is significantly reduced from (55 to 80 mol%) in Fig. 4, which is phosphorus P ₂ O ₅ (5 to 20 mol%) and calcium CaO (5 because the addition of such as 20% by mole), is decreased by a first number of the main material of the addition ratio of vanadium V ₂ O _5.

FIG. 10B shows an explanation of an example of the upper limit and the lower limit of barium BaO (actually, BaCO ₃ is added to a raw material, and CO ₂ is released to form BaO at the time of heating melting).

When barium BaO (BaCO ₃ ) is below the lower limit (10 mol%), homogeneous vitrification becomes difficult.

When barium BaO (BaCO ₃ ) is above the upper limit (40 mol%), the mechanical strength deteriorates.

FIG. 10C shows an explanation of other additives (for example, two kinds of additives of FIG. 10D).

The aluminum material trivalent plays a role of not disturbing or increasing the formation of a P-type function for the silicon tetravalent. In some cases, it may not be added.

10 (d) shows an example of an additive.

Aluminum Al ₂ O ₃ (1-10 mol%):

Boron B ₂ O ₃ (5-20 mol%):

Balance of the blending ratio of these two components is important. Otherwise, uniformity will not be maintained and crystals will precipitate out and do not glass.

10 (e) shows an example of addition of phosphorus P ₂ O ₅ (5 to 20 mol%) and calcium CaO (5 to 20 mol%). To add phosphorus P ₂ O ₅ (5 to 20 mol%) and calcium CaO (5 to 20 mol%), tricalcium phosphate Ca ₃ (PO ₄ ) ₂ is added.

Since phosphorus reacts with water, it is preferable to add it as phosphoric acid.

Since the compound containing an alkali metal produces the solar cell characteristic deterioration, the phosphorus compound with an alkaline earth metal (for example, calcium) is added.

When adding compounds of boron (trivalent), phosphorus (pentavalent) and antimony (pentavalent), adding three kinds at the same time compared with two kinds of boron and phosphorus in I / V characteristics and adhesion Falls behind

In addition, experiments were conducted by adding tricalcium phosphate Ca ₃ (PO ₄ ) ₂ or calcium metaphosphate Ca (PO ₃ ) ₂ as a phosphorus compound with the alkaline earth metal (for example, calcium). Particularly, the former tricalcium phosphate Ca ₃ (PO ₄ ) ₂ is used as a food additive and can be obtained inexpensively. In addition, the number of oxygen O is 8 (the latter is 6) in comparison with the latter, but good results are obtained. lost. In addition, when producing the glass frit of the present invention, a small amount of carbon C (including a compound) may be attached or mixed in the raw material, and the amount of carbon C may be oxidized to the oxygen O to produce gas (carbon dioxide CO _2). It is also possible to purify by releasing as a material), so that it is necessary to include some oxygen O.

In addition, when the phosphoric acid P ₂ O ₅ and calcium CaO were added directly, favorable glass frit was impossible to manufacture. Similarly, when calcium CaO is added to an alkali earth metal other than alkaline earth metal, for example, sodium or potassium, it is deteriorated and unusable when exposed to strong sunlight such as a solar cell for a long time (for example, 10 years or more).

Fig. 11 shows an explanatory diagram (2) of the aluminum electrode firing frit for solar cells of the present invention. This is the problem (requirement) (1), (2), (3) which is required for the glass frit to be mixed in the aluminum paste when the aluminum paste is applied and sintered on the back surface of the solar cell to form the aluminum electrode. (4) and the means which this invention solves are made into table | surface in correspondence.

Fig. 11A shows the problem "(1) low melting point" and the solution of the present invention. In the present invention, as described above, vanadium and barium are mainly used to realize 600 ° C. or less. This is because the sintering temperature is determined at the midpoint between the melting point of aluminum (660 ° C) and the melting point of the frit. In the present invention, the melting point of the glass frit is defined to be 650 ° C or less, and in experiments, 600 ° C or less can be achieved.

FIG. 11B shows the problem "(2) Component structure which does not affect the lifetime of a silicon solar cell" and means for solving the present invention. In the present invention, iron, copper, nickel, chromium and the like are not included as described above. The basis is a combination of vanadium, barium, aluminum, boron, phosphorus, calcium and zinc. Here, aluminum and boron are the contact materials of back side aluminum.

As described above, since the glass frit is made of a material that does not contain iron, copper, nickel, chromium, or the like, which adversely affects the long term excessive use conditions in the solar cell, these adverse effects can be avoided.

Fig. 11C shows the problem "(3) the silicon substrate is not bent at the time of sintering" and the solution means of the present invention. In the present invention, the warpage of the substrate during sintering of aluminum is eliminated by the components of vanadium and barium as described above.

Fig. 11 (d) shows the problem "(4) adhesiveness and I / V improvement" and the solution of the present invention. In the present invention, as described above, the constituents to which phosphorus, calcium, and the like are added have good adhesiveness to the substrate during aluminum sintering and also improve the I / V characteristics.

Next, using Fig. 12 to Fig. 14, the glass frit of the present invention already described in Figs. 1 to 11 is added as a preparation to prepare an aluminum paste, and the prepared aluminum paste is applied to the back surface of the solar cell. The process of sintering and forming an aluminum electrode is demonstrated in detail sequentially.

12 shows an explanatory view of the aluminum paste of the present invention. This is an example of the component of an aluminum paste, for example as shown. These components are mixed to produce an aluminum paste (see Figure 13).

(1) Aluminum powder:

Purity: 99.7% or more

Average particle size: 1-20 μm

Shape: ball shape, ball shape of ellipse

(2) Vanadate glass (glass frit) of the present invention:

Particle diameter: 1-3 μm

0.1-1% weight ratio of the whole aluminum paste

(3) Other glass powder:

Particle diameter: 1-3 μm

0-1% weight ratio of the whole aluminum paste

(4) Resin:

0.1-3% by weight of the total aluminum paste

Ethyl celluloses, nitrocelluloses, etc.

(5) Solvent:

· Weight ratio-25% of the total aluminum paste (clay suitable for screen printing, etc.)

Diethylene glycol, monobutyl ether, etc.

Fig. 13 shows a manufacturing flowchart of the aluminum paste of the present invention.

In Fig. 13, S21 mixes a solvent and a resin in a mixer (organic vehicle). This puts the solvent (5) and resin (4) of FIG. 12 which were already described in a mixer, and mixes well, and manufactures an organic vehicle.

S22 mixes glass with an organic vehicle. This puts the vanadate glass powder (glass frit) of FIG. 12 (2) of this invention described above into the organic vehicle manufactured by S21, and (3) other glass powder as needed, and mixes well. .

S23 mixes aluminum powder. This is a step of further mixing the aluminum powder of Fig. 12 (1) already described, and with respect to 100 parts by weight of aluminum powder of Fig. 12 (1), 1.5 to 100 parts by weight of an organic vehicle (preferably 30 to 50% by weight). And (b), the aluminum powder of (1) is mixed.

S24 completes aluminum paste.

According to the procedures of S21 to S24 described above, the solvent (4) and the resin (4) and the vanadate glass powder (glass frit) of the present invention described above and (3) other glass as necessary The powder and (1) aluminum powder are mixed well in order in a mixer, whereby an aluminum paste can be produced.

14 shows a firing flow chart of the aluminum paste of the present invention. This shows an example of the baking flow chart at the time of apply | coating, drying, and baking the aluminum paste manufactured in FIG.

In Fig. 14, S31 is applied to the back surface of the solar cell and the silicon surface. For example, it is applied in a thickness of 5 to 13 mg / cm ² . This is applied directly to the back surface of the solar cell, for example, on the object for forming the aluminum electrode, or directly on the silicon surface on the back surface of the silicon substrate.

S32 is dried. This puts the aluminum paste apply | coated in S31 in the drying furnace of 100-300 degreeC for 1 minute-10 minutes, for example, to volatilize and dry a solvent. In addition, hot air may be supplied and dried.

S33 sinters aluminum. This is put in a sintering furnace of about 500 to 900 ° C (1200 ° C if necessary) for 1 to 300 seconds and sintered to form an aluminum electrode on the back surface or silicon surface of the solar cell. Moreover, you may sinter by irradiating an infrared ray directly with an infrared lamp. At the time of sintering, the vanadate glass of the present invention, in particular, is melted and firmly adhered to the back surface or silicon surface of the solar cell, and strongly adhered to aluminum powder, and has a strong adhesion force that could not be realized in the conventional glass powder. It was confirmed to exert. In other words, when the lead wire was soldered to the aluminum electrode formed by sintering, it was confirmed by experiment that the pull wire was not easily peeled off as in the prior art, and there was a conventional multiple times of bonding strength.

S34 is completed by cooling to room temperature. This is cooled to room temperature after sintering aluminum in S33 to complete formation of an aluminum electrode on the back surface and the silicon surface of the solar cell.

As mentioned above, the aluminum paste which added the vanadate glass powder of this invention as a preparation is apply | coated to the back surface or silicon surface of a solar cell (S31), dried (S32), and then baked (S33), and solar cell It has become possible to form an aluminum electrode adhered on the back surface or silicon surface of the substrate several times stronger than before.

Claims (17)

In a glass frit that is incorporated into a conductive paste that is coated and sintered to a substrate to form a conductive electrode,
It is produced by melting vanadium V ₂ O ₅ from 55 to 80 mol% and barium BaO from 15 to 30 mol% as a main material to produce a molten glass, which is prepared by pulverizing rapidly cooled debris and melting below 650 ° C. Glass frit.
The method of claim 1,
As an additive, at least one of aluminum Al ₂ O ₃ from 0 to 10 mol%, boron B ₂ O ₃ from 0 to 7 mol% and silicon SiO ₂ from 0 to 7 mol% are mixed with the main material and heated to melt Glass frit characterized in that the glass produced.
The method of claim 2,
Glass frit, characterized in that it does not contain iron, copper, nickel, chromium.
The method according to any one of claims 1 to 3,
An aluminum paste as said conductive paste is used, The glass frit.
The method according to any one of claims 1 to 4,
A glass frit formed by coating and sintering to said substrate to form a conductive electrode, and applying and sintering to a substrate of a solar cell to form a conductive aluminum electrode.
The aluminum paste which added the glass frit of any one of Claims 1-5 as a preparation.
In a glass frit that is incorporated into a conductive paste that is coated and sintered to a substrate to form a conductive electrode,
10 to 55 mol% of vanadium V ₂ O ₅ and 10 to 40 mol% of barium BaO are heated as a main material to produce a molten glass, which is prepared by pulverizing rapidly cooled debris and melting below 650 ° C. Glass frit.
The method of claim 7, wherein
The glass frit, characterized in that the molten glass was produced by incorporating aluminum Al ₂ O ₃ from 1 to 10 mol% and boron B ₂ O ₃ from 1 to 20 mol% into the main material and heating.
The method according to claim 7 or 8,
The glass frit, characterized in that the molten glass was produced by mixing phosphorus P ₂ O ₅ from 5 to 20 mol% and calcium CaO from 5 to 20 mol% into the main material and heating.
The method of claim 8,
The additives of the glass frit as the calcium as CaO to be added with a P ₂ O _5, characterized in that in one or more than one compound of phosphorus and the alkaline earth metal.
The method of claim 10,
Calcium CaO added together with phosphorus P ₂ O ₅ , tricalcium phosphate Ca ₃ (PO ₄ ) ₂ or calcium metaphosphate Ca (PO ₃ ), which is one or more compounds of phosphorus and alkaline earth metals Glass frit characterized by _two .
The method according to any one of claims 7 to 11,
Glass frit, characterized in that it does not contain iron, copper, nickel, chromium.
The method according to any one of claims 7 to 12,
An aluminum paste as said conductive paste is used, The glass frit.
The method according to any one of claims 7 to 13,
A glass frit formed by coating and sintering to said substrate to form a conductive electrode, and applying and sintering to a substrate of a solar cell to form a conductive aluminum electrode.
The aluminum paste which added the glass frit of any one of Claims 7-14 as a preparation.
In the method of manufacturing a glass frit, which is incorporated into a conductive paste that is coated and sintered to a substrate to form a conductive electrode,
Melted glass is heated by heating vanadium V ₂ O ₅ from 55 to 80 mol% and barium BaO from 15 to 30 mol% as a main material,
The resulting molten glass is rapidly cooled to generate debris,
The resulting debris is pulverized to produce a glass frit that is melted at 650 ° C. or lower.
Glass frit manufacturing method characterized by.
In the method of manufacturing a glass frit, which is incorporated into a conductive paste that is coated and sintered to a substrate to form a conductive electrode,
Molten glass is produced by heating vanadium V ₂ O ₅ from 10 to 550 mol% and barium BaO from 10 to 40 mol% as a main material,
The resulting molten glass is rapidly cooled to generate debris,
The resulting debris is pulverized to produce a glass frit that is melted at 650 ° C. or lower.
Glass frit manufacturing method characterized by.

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