JP2011126722A - Sealing material for sealing laser, glass member with sealing material layer and solar cell using the member and method for producing the solar cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing material for sealing a laser, capable of improving the seal reliability between glass substrates by relaxing the residual stress produced on the joint interface between the glass substrate and a sealing layer. <P>SOLUTION: The sealing material for sealing the laser contains: sealing glass comprising low melting point glass; a low-expansion filler of 5-25% mass ratio; a laser absorbing material of 1-10% mass ratio; and a hollow bead of 0.5-7% mass ratio. The sealing material is baked and stuck to a sealing area of the glass substrate 3 to form a sealing material layer 6. The sealing material-stuck glass substrate 3 is layered on the glass substrate 2 while interposing the sealing material layer 6 between them. The sealing material layer 6 is irradiated with a laser beam 7 and melted to seal the space between the glass substrates 2 and 3. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a sealing material for laser sealing, a glass member with a sealing material layer, a solar cell using the same, and a method for manufacturing the solar cell.

  In a solar cell such as a dye-sensitized solar cell, application of a glass package in which a battery element part (photoelectric conversion element part) is sealed with two glass substrates is being promoted. As a sealing material for sealing between two glass substrates, a sealing glass having excellent weather resistance, moisture resistance and the like is used. However, since the sealing temperature by sealing glass is about 400-600 degreeC, the characteristic of a battery element part will deteriorate in the heat processing using a baking furnace. Therefore, a laser that arranges a sealing material layer including a sealing glass and a laser absorber on the periphery of two glass substrates, and irradiates the laser beam on the sealing material layer to locally heat and melt the sealing material layer. Application of sealing has been studied (see Patent Document 1).

  Laser sealing using local heating with laser light can suppress the thermal effect on the battery element, but it is a process in which the sealing material layer is rapidly heated and cooled locally, so the sealing material layer is melted. There is a drawback that residual stress tends to occur at the bonding interface between the sealing layer made of the fixing layer and the glass substrate. Residual stress at the bonding interface is a factor that causes cracks and cracks in the sealing portion and the glass substrate. In particular, solar cells installed outdoors are repeatedly subjected to thermal cycles based on the temperature difference between daytime and nighttime. Therefore, in glass packages with residual stress at the bonding interface, sealing parts and glass Cracks and cracks are likely to occur on the substrate.

  In applying local heating by laser light to sealing of a glass panel, as described in Patent Document 1, the difference in thermal expansion coefficient between the sealing material layer and the glass substrate is reduced to generate thermal stress. Attempts have been made to suppress. Further, Patent Document 2 describes a sealing material which has a low expansion by adding a low expansion filler such as silica, alumina, zirconia, cordierite, zirconium phosphate to bismuth-based sealing glass (glass frit). ing. However, by merely approximating the thermal expansion coefficient of the sealing material layer to that of the glass substrate, the residual stress at the bonding interface due to local rapid cooling of the sealing material layer after laser irradiation cannot be sufficiently relaxed. .

JP 2008-115057 A JP 2006-137737 A

  The object of the present invention is to relieve the residual stress generated at the bonding interface between the glass substrate and the sealing layer when applying local heating by laser light to the sealing between the two glass substrates. A laser sealing sealing material and a glass member with a sealing material layer capable of increasing the sealing reliability, and further improving the long-term reliability by using such a glass member with a sealing material layer. It is in providing a battery and its manufacturing method.

  The sealing material for laser sealing according to an aspect of the present invention includes a sealing glass made of low-melting glass, a low expansion filler in a mass ratio of 5 to 25%, and a laser absorber in a range of 1 to 10%. And hollow beads in the range of 0.5 to 7%.

  A glass member with a sealing material layer according to an aspect of the present invention is provided on a glass substrate having a sealing region and the sealing region of the glass substrate, and the laser sealing sealing material according to the aspect of the present invention. And a sealing material layer made of a fired layer.

  A solar cell according to an aspect of the present invention includes a first glass substrate having a first surface including a first sealing region, and a second sealing region corresponding to the first sealing region. A second glass substrate disposed so that the second surface faces the first surface of the first glass substrate, the first glass substrate, and the second glass substrate. Of the first sealing region of the first glass substrate and the second glass substrate so as to seal the solar cell element portion provided between the glass substrate and the solar cell element portion. And a sealing layer formed between the second sealing region and formed of a melt-fixed layer of the sealing material according to an aspect of the present invention.

  The method for manufacturing a solar cell according to an aspect of the present invention includes a step of preparing a first glass substrate having a first surface including a first sealing region, and the first sealing of the first glass substrate. 2nd surface provided with the 2nd sealing area | region corresponding to a stop area | region, and the sealing material layer which consists of a baking layer of the sealing material which is formed on the said 2nd sealing area | region, and concerns on the aspect of this invention Preparing the second glass substrate having the first glass substrate and the second glass substrate, the sealing material so that the first surface and the second surface face each other. Laminating through a layer, and irradiating the sealing material layer with laser light through the first glass substrate or the second glass substrate to melt the sealing material layer, thereby the first glass substrate. And a sealing layer for sealing a solar cell element portion provided between the second glass substrate and the second glass substrate It is characterized by comprising the step of forming.

  According to the sealing material for laser sealing and the glass member with a sealing material layer according to the aspect of the present invention, residual stress generated at the bonding interface between the glass substrate and the sealing layer during laser sealing can be relaxed. Therefore, according to the solar cell and the manufacturing method thereof according to the aspect of the present invention, it is possible to suppress cracks and cracks of the sealing portion and the glass substrate due to the residual stress at the bonding interface over time, and thereby, for a long time. Reliability can be increased.

It is sectional drawing which shows the structure of the solar cell by embodiment of this invention. It is sectional drawing which expands and shows the battery element part of the solar cell shown in FIG. It is sectional drawing which shows the manufacturing process of the solar cell by embodiment of this invention. It is a top view which shows the 1st glass substrate used at the manufacturing process of the solar cell shown in FIG. It is sectional drawing along the AA line of FIG. It is a top view which shows the 2nd glass substrate used at the manufacturing process of the solar cell shown in FIG. It is sectional drawing along the AA line of FIG. It is a figure which shows the relationship between the sealing temperature in Example 1 of this invention, and a residual stress.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a solar cell according to an embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view showing a battery element portion of the solar cell shown in FIG. 1, and FIG. FIGS. 4 to 7 are views showing the steps, and FIGS. 4 to 7 are views showing the structures of the first and second glass substrates used therefor.

A solar cell 1 shown in FIG. 1 is a solar cell having an electrochemical wet cell structure such as a dye-sensitized solar cell. The solar cell 1 includes a first glass substrate 2 and a second glass substrate 3. For example, soda lime glass substrates are used as the first and second glass substrates 2 and 3. Various known compositions can be applied to the soda lime glass substrate. The soda lime glass substrate which comprises the 1st and 2nd glass substrates 2 and 3 has a thermal expansion coefficient of the range of 80-90 * 10 < ^-7 > / (degreeC), for example.

  A battery element portion 4 is provided between the surface 2a of the first glass substrate 2 and the surface 3a of the second glass substrate 3 facing it. The battery element unit 4 includes, for example, a dye-sensitized solar cell element (dye-sensitized photoelectric conversion element). The structure of the battery element unit 4 is not particularly limited, and various known element structures can be applied. The solar cell 1 of this embodiment is not limited to the element structure of the battery element unit 4. FIG. 2 shows an example of the structure of the dye-sensitized solar cell element 40 as a configuration example of the battery element unit 4.

  In the dye-sensitized solar cell element 40 shown in FIG. 2, a semiconductor electrode (photoelectrode / anode) 42 having a sensitizing dye is provided on the surface 2 a of the first glass substrate 2 via a transparent conductive film 41. Yes. A counter electrode (cathode) 44 is provided on the surface 3 a of the second glass substrate 3 via a transparent conductive film 43. The transparent conductive films 41 and 43 constitute a wiring film and are made of, for example, fluorine-doped tin oxide (FTO) or indium tin oxide (ITO). The transparent conductive films 41 and 43 are not limited to single films such as FTO films and ITO films, but some of them are other conductive films (Al films, Al alloy films, Cu films, Cu alloy films, etc.) and insulating films (SiOx films and SiNx films). It may be a laminated film laminated with a film or the like.

  The semiconductor electrode 42 is composed of a porous film of a metal oxide such as titanium oxide, zirconium oxide, niobium oxide, tantalum oxide, tin oxide, and zinc oxide, and a sensitizing dye is adsorbed therein. Examples of the sensitizing dye include metal complex dyes such as ruthenium complex dyes and osmium complex dyes, and organic dyes such as cyanine dyes, merocyanine dyes, and triphenylmethane dyes. The counter electrode 44 is made of a thin film such as platinum, gold, or silver. An electrolyte 45 is enclosed between the first glass substrate 2 and the second glass substrate 3, and the dye-sensitized solar cell element 40 is configured by these components.

  As shown in FIGS. 4 and 5, the surface 2 a of the first glass substrate 2 used for manufacturing the solar cell 1 is a first element on which an element structure 4 </ b> A that becomes a part of the battery element unit 4 is formed. A region 2A and a first sealing region 2B provided along the outer periphery thereof are provided. The first sealing region 2B is provided so as to surround the first element region 2A. As shown in FIGS. 6 and 7, the surface 3a of the second glass substrate 3 has a second element region 3A corresponding to the first element region 2A and a second element region corresponding to the first sealing region 2B. Sealing region 3B. In the second element region 3 </ b> A, an element structure 4 </ b> B that becomes a part of the battery element unit 4 is formed. As described above, the element structures 4A and 4B have element films such as wiring films and electrode films, and element structures based thereon.

  The first glass substrate 2 and the second glass substrate 3 are arranged with a predetermined gap so that the surfaces 2a and 3a on which the element structures 4A and 4B constituting the battery element portion 4 are formed face each other. Is done. The gap between the first glass substrate 2 and the second glass substrate 3 is hermetically sealed with a sealing layer 5. That is, the sealing layer 5 is formed between the sealing region 2B of the first glass substrate 2 and the sealing region 3B of the second glass substrate 3 so as to hermetically seal the battery element portion 4. . The battery element portion 4 is hermetically sealed with a glass panel composed of the first glass substrate 2, the second glass substrate 3, and the sealing layer 5. The sealing layer 5 has a thickness in the range of 20 to 100 μm, for example.

  The sealing layer 5 seals the first glass substrate 2 by irradiating the sealing material layer 6 formed in the sealing region 3 </ b> B of the second glass substrate 3 with a laser beam and melting it, followed by rapid cooling. It consists of a melt-fixed layer fixed to the region 2B. As shown in FIGS. 6 and 7, a frame-shaped sealing material layer 6 is formed in the sealing region 3 </ b> B of the second glass substrate 3. The sealing material layer 6 is irradiated with laser light. Then, the first glass substrate 2 and the second glass substrate 3 are melted and fixed to the sealing region 2B of the first glass substrate 2 by heat generated based on the irradiation of the laser light. The sealing layer 5 that hermetically seals the space between the two is formed.

  The sealing material layer 6 is a fired layer of a sealing material containing sealing glass, a low expansion filler, a laser absorber, and hollow beads. The sealing material is obtained by blending a laser absorbing material, a low expansion filler and hollow beads into sealing glass as a main component. The sealing material may contain additives other than these as required. For the sealing glass (glass frit), for example, low melting point glass such as bismuth glass, tin-phosphate glass, vanadium glass, and lead glass is used. Among these, it is preferable to use bismuth glass or tin-phosphate glass in consideration of sealing properties to the glass substrates 2 and 3, reliability thereof, influence on the environment and human body, and the like. It is desirable to use bismuth-based glass having excellent weather resistance and the like.

Bismuth-based glass (gas frit) is composed of 70 to 90% by mass of Bi ₂ O ₃ , 1 to 20% by mass of ZnO, and 2 to 18% by mass of B ₂ O ₃ (basically, the total amount is 100% by mass). It is preferable to have a composition of Bi ₂ O ₃ is a component that forms a glass network. When the content of Bi ₂ O ₃ is less than 70% by mass, the softening point of the low-melting glass becomes high and sealing at a low temperature becomes difficult. When the content of Bi ₂ O ₃ exceeds 90% by mass, it becomes difficult to vitrify and the thermal expansion coefficient tends to be too high.

ZnO is a component that lowers the thermal expansion coefficient and the like. Vitrification becomes difficult when the content of ZnO is less than 1% by mass. When the content of ZnO exceeds 20% by mass, stability during low-melting glass molding is lowered, and devitrification is likely to occur. B ₂ O ₃ is a component that forms a glass skeleton and widens the range in which vitrification is possible. If the content of B ₂ O ₃ is less than 2% by mass, vitrification becomes difficult. If the content of B ₂ O ₃ exceeds 18% by mass, the softening point becomes too high, and it becomes difficult to seal at a low temperature even if a load is applied during sealing.

A glass formed of three components (basic components) of Bi ₂ O ₃ , ZnO, and B ₂ O ₃ has a low transition point and is suitable as a sealing material for low temperature, but Al ₂ O ₃ , CeO ₂ , CuO Fe ₂ O ₃ , Ag ₂ O, WO ₃ , MoO ₃ , Nb ₂ O ₃ , Ta ₂ O ₅ , Ga ₂ O ₃ , Sb ₂ O ₃ , Li ₂ O, Na ₂ O, K ₂ O, Cs ₂ O, CaO, SrO, BaO, WO 3, SiO 2, P 2 O 5, SnO x (x is a is 1 or 2) may contain optional components such. However, if the content of any component is too large, the glass becomes unstable and devitrification may occur, and the glass transition point and softening point may increase. Therefore, the total content of any component is 30% by mass. The following is preferable. The glass composition in this case is adjusted so that the total amount of the basic component and the optional component is basically 100% by mass.

Among the optional components described above, Al ₂ O ₃ is a component that lowers the thermal expansion coefficient and improves the stability of the low-melting glass during firing. The content of Al ₂ O ₃ is preferably in the range of 0 to 5% by mass, more preferably in the range of 0.1 to 5% by mass. If the content of Al ₂ O ₃ exceeds 5% by mass, the viscosity of the glass increases, and Al ₂ O ₃ tends to remain as an unmelted material in the low-melting glass. By containing Al ₂ O ₃ in an amount of 0.1% by mass or more, the stability of the low-melting glass during firing can be more effectively increased.

Fe ₂ O ₃ is a component that expands the temperature range that can be sealed by suppressing the crystallization of the glass during sealing without substantially increasing the viscosity. However, since the vitrification range is narrowed when Fe ₂ O ₃ is added excessively, the content is preferably in the range of 0 to 0.5 mass%, more preferably 0.01 to 0.2 mass%. Range. CuO is a component that lowers the viscosity of the glass and expands the temperature range that can be sealed especially on the low temperature side, and its content is preferably in the range of 0 to 5 mass%, more preferably 0.1 to 3 mass%. % Range. When the content of CuO exceeds 5% by mass, the deposition rate of crystals increases, and the temperature range where sealing is possible on the high temperature side becomes narrow.

CeO ₂ is a component that suppresses the precipitation of Bi ₂ O ₃ in the glass composition as metallic bismuth when the glass is melted and stabilizes the fluidity of the glass. The CeO ₂ content is preferably in the range of 0 to 5% by mass, more preferably in the range of 0.1 to 5% by mass. When the content of CeO ₂ exceeds 5% by mass, the viscosity of the glass becomes high and sealing at a low temperature becomes difficult. Furthermore, CeO ₂ has an effect of suppressing crucible deterioration (erosion and cracking) when melting bismuth glass with a crucible made of Pt or a Pt alloy.

  As the laser absorbing material blended in the sealing material, for example, at least one metal selected from Fe, Cr, Mn, Co, Ni and Cu, an oxide of the metal (including a composite oxide), and the like are used. . The content of the laser absorber is preferably in the range of 0.1 to 10% by mass with respect to the sealing material. When the content of the laser absorber is less than 0.1% by mass, the sealing material layer 6 cannot be sufficiently melted when irradiated with laser light. If the content of the laser absorbing material exceeds 10% by mass, the second glass substrate 3 may be cracked due to local heat generation near the interface with the second glass substrate 3 when irradiated with laser light, or There is a possibility that the fluidity at the time of melting of the sealing material is deteriorated and the adhesiveness with the first glass substrate 2 is lowered.

Low expansion fillers to be blended into the sealing material include silica, alumina, zirconia, zirconium silicate, aluminum titanate, mullite, cordierite, eucryptite, spodumene, zirconium phosphate compounds, tin oxide compounds, quartz At least one selected from solid solutions is used. Zirconium phosphate compounds include (ZrO) ₂ P ₂ O ₇ , NaZr ₂ (PO ₄ ) ₃ , KZr ₂ (PO ₄ ) ₃ , Ca _0.5 Zr ₂ (PO ₄ ) ₃ , Na _0.5 Nb _0.5 Zr _1.5 ( PO ₄ ) ₃ , K _0.5 Nb _0.5 Zr _1.5 (PO ₄ ) ₃ , Ca _0.25 Nb _0.5 Zr _1.5 (PO ₄ ) ₃ , NbZr (PO ₄ ) ₃ , Zr ₂ (WO ₃ ) (PO ₄ ) ₂ , these Examples include complex compounds. The low expansion filler has a lower thermal expansion coefficient than the sealing glass which is the main component of the sealing material.

  The content of the low expansion filler is appropriately set so that the thermal expansion coefficient of the sealing glass approaches the thermal expansion coefficient of the glass substrates 2 and 3. The low expansion filler is preferably contained in the range of 2 to 25% by mass with respect to the sealing material, although it depends on the thermal expansion coefficient of the sealing glass and the glass substrates 2 and 3. If the content of the low expansion filler is less than 2% by mass, the effect of adjusting the thermal expansion coefficient of the sealing material cannot be sufficiently obtained. On the other hand, if the content of the low expansion filler exceeds 25% by mass, the fluidity of the sealing material may be reduced, and the adhesive strength may be reduced.

  By the way, when laser light is used for local heating of the sealing material layer 6, the sealing material layer 6 is melted in order from the portion irradiated with the laser light scanned along the sealing material layer 6 and rapidly cooled and solidified upon completion of the laser light irradiation. And fixed to the first glass substrate 2. The sealing material layer 6 is locally heated and quenched as the laser beam is irradiated. In this manner, the sealing material layer 6 is melted by rapidly heating the irradiated portion of the laser beam, and is rapidly cooled and solidified after the laser beam has passed. When a conventional sealing material is used, a large residual stress is generated at the bonding interface between the sealing layer 5 that is a melt-solidified layer of the sealing material layer 6 and the glass substrates 2 and 3 during rapid cooling after the passage of laser light. Arise.

  The residual stress at the bonding interface between the glass substrates 2 and 3 and the sealing layer 5 is that of the glass panel constituted by the first glass substrate 2, the second glass substrate 3 and the sealing layer 5, and consequently the solar cell 1. It becomes a factor which reduces reliability. In particular, the solar cell 1 installed outdoors is repeatedly subjected to a thermal cycle based on a temperature difference between daytime and nighttime. Therefore, if a residual stress is generated at the bonding interface, the sealing layer 5 or glass Cracks and cracks are likely to occur in the substrates 2 and 3. This is a factor that reduces the temporal reliability (long-term reliability) of the solar cell 1.

  In contrast, the sealing material of this embodiment contains hollow beads. The hollow beads may be any shape as long as the hollow beads have a shape (hollow shape) having closed pores and the hollow shape is maintained when the sealing material layer 6 is locally heated with laser light. Specific examples of such hollow beads include hollow glass beads made of a glass material selected from borosilicate glass, aluminosilicate glass, and soda lime glass. Since these glass materials have a higher transition point and softening point than sealing glass, which is the main component of the sealing material, a hollow shape is maintained even during laser sealing. The hollow beads are not limited to the hollow glass beads, and any hollow beads having the same shape and characteristics as the hollow glass beads described above can be used. For example, hollow ceramic beads such as hollow silica beads can be used.

The hollow beads present in the sealing material layer 6 function as a relieving material for residual stress generated during laser sealing. That is, the stress generated in the local quenching region after laser light irradiation is relieved by elasticity based on the shape of the hollow beads (deformability based on the hollow shape). Furthermore, the residual stress σ of the joined body of the sealing layer 5 and the glass substrates 2 and 3 can be obtained from the following equation.
σ = α · ΔT · E / (1-ν)
Here, α is a thermal expansion coefficient, E is a Young's modulus, ΔT is a temperature difference, and ν is a Poisson's ratio. When the sealing material layer 6 containing hollow beads is used, the Young's modulus E of the sealing layer 5 is lowered, so that residual stress can be reduced. By these, it becomes possible to relieve the residual stress generated at the bonding interface between the glass substrates 2 and 3 and the sealing layer 5.

  The content of the hollow beads is preferably in the range of 0.5 to 7% by mass with respect to the sealing material. When the content of the hollow beads is less than 0.5% by mass, the above-described residual stress relaxation effect by the hollow beads cannot be sufficiently obtained. When the content of the hollow beads exceeds 7% by mass, the fluidity of the sealing material is lowered, and the adhesive strength and the like may be lowered. Moreover, it is preferable that the shape of the hollow beads has a maximum particle size of not more than the distance between the glass substrates 2 and 3 and an average particle size in the range of 1 to 15 μm. If the average particle diameter of the hollow beads exceeds 15 μm, the denseness of the sealing layer 5 may be impaired, and thereby the hermetic sealing property tends to be lowered. When the average particle size of the hollow beads is less than 1 μm, the fluidity of the sealing material tends to be lowered due to the increase in the surface area. If the content can maintain fluidity, the residual stress relaxation effect tends to be insufficient.

  The hollow beads have a ratio of the total volume B of the voids in the hollow beads to the total volume A (total volume of the sealing material) A of the sealing glass, the low expansion filler, the laser absorber, and the hollow beads (B / A × 100 [%] (porosity of the sealing material) is preferably 1 to 20%. When the porosity of the sealing material is less than 1%, there is a possibility that the effect of relaxing the residual stress by the hollow beads cannot be obtained sufficiently. On the other hand, when the porosity of the sealing material exceeds 20%, the hermetic sealing performance by the sealing layer 5 decreases, or the strength of the sealing layer 5 itself becomes insufficient and the sealing performance is reduced. Its reliability may be reduced. The porosity (B / A × 100 [%]) of the sealing material is more preferably in the range of 1.5 to 15%.

  The sealing material layer 6 is formed on the sealing region 3B of the second glass substrate 3 as follows. First, a sealing material paste is prepared by mixing a sealing material with a vehicle. Examples of the vehicle include those obtained by dissolving a resin such as methyl cellulose, ethyl cellulose, carboxymethyl cellulose, oxyethyl cellulose, benzyl cellulose, propyl cellulose, and nitrocellulose in a solvent such as terpineol, butyl carbitol acetate, and ethyl carbitol acetate. ) Acrylic resins such as acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-hydroxyethyl methacrylate, etc. dissolved in a solvent such as methyl ethyl ketone, terpineol, butyl carbitol acetate, ethyl carbitol acetate, etc. Used.

  The viscosity of the sealing material paste may be adjusted to the viscosity corresponding to the apparatus applied to the glass substrate 3, and can be adjusted by the ratio of the resin (binder component) and the solvent and the ratio of the sealing material and the vehicle. A known additive may be added to the sealing material paste as a glass paste such as an antifoaming agent or a dispersing agent. A known method using a rotary mixer equipped with a stirring blade, a roll mill, a ball mill or the like can be applied to the preparation of the sealing material paste.

  A sealing material paste is applied to the sealing region 3B of the second glass substrate 3 and dried to form an application layer of the sealing material paste. The sealing material paste is applied onto the second sealing region 3B by applying a printing method such as screen printing or gravure printing, or is applied along the second sealing region 3B using a dispenser or the like. To do. The coating layer of the sealing material paste is preferably dried at a temperature of 120 ° C. or more for 10 minutes or more, for example. A drying process is implemented in order to remove the solvent in an application layer. If the solvent remains in the coating layer, the binder component may not be sufficiently removed in the subsequent firing step.

  The coating layer of the sealing material paste described above is baked to form the sealing material layer 6. In the firing step, the coating layer is first heated to a temperature below the glass transition point of sealing glass (glass frit), which is the main component of the sealing material, and the binder component in the coating layer is removed, and then the sealing glass (glass The sealing material is melted and baked on the glass substrate 3 by heating to a temperature equal to or higher than the softening point of the frit. In this way, the sealing material layer 6 composed of the fired layer of the sealing material is formed.

  As shown in FIG. 3, the solar cell 1 of this embodiment includes a second glass substrate 3 (including an element structure 4B) having a sealing material layer 6 and a first glass substrate 2 (separately produced) ( The element structure 4A is provided). First, as shown to Fig.3 (a), the 1st glass substrate 2 and the 2nd glass substrate 3 are arrange | positioned so that those surfaces 2a and 3a may oppose. Next, as shown in FIG. 3 (b), the first glass substrate 2 and the second glass substrate 3 are laminated via the sealing material layer 6. Between the first glass substrate 2 and the second glass substrate 3, a gap serving as an arrangement space for the battery element unit 4 is formed based on the thickness of the sealing material layer 6.

  Next, as shown in FIG. 3C, the sealing material layer 6 is irradiated with a laser beam 7 through the second glass substrate 3 (or the first glass substrate 2). The laser beam 7 is irradiated while scanning along the frame-shaped sealing material layer 6. The laser beam 7 is not particularly limited, and a laser beam from a semiconductor laser, a carbon dioxide laser, an excimer laser, a YAG laser, a HeNe laser, or the like is used. The output of the laser beam 7 is appropriately set according to the thickness of the sealing material layer 6 and the like, and the heating temperature (processing temperature) of the sealing material layer 6 is in the range of 450 to 800 ° C. It is preferable to apply the output. If the heating temperature of the sealing material layer 6 is less than 450 ° C., the sealing material layer 6 may not be sufficiently melted. On the other hand, when the heating temperature of the sealing material layer 6 exceeds 800 ° C., cracks and cracks are likely to occur in the glass substrates 2 and 3 during heating.

  The sealing material layer 6 is melted in order from the portion irradiated with the laser beam 7 scanned along the sealing material layer 6, and is rapidly cooled and solidified and fixed to the first glass substrate 2 when the irradiation of the laser beam 7 is completed. And sealing which seals between the 1st glass substrate 2 and the 2nd glass substrate 3 as shown in FIG.3 (d) by irradiating a laser beam over the perimeter of the sealing material layer 6 Layer 5 is formed. Since the sealing material layer 6 contains hollow beads, residual stress generated at the bonding interface between the glass substrates 2 and 3 and the sealing layer 5 during laser sealing can be reduced.

  In this manner, the battery element portion 4 formed in the element regions 2A and 3A was hermetically sealed with the glass panel constituted by the first glass substrate 2, the second glass substrate 3, and the sealing layer 5. The solar cell 1 is produced. The reliability of the solar cell 1 depends on whether or not such a hermetic sealability can be maintained over a long period of time in addition to the hermetic sealability of the glass package at the initial stage of sealing. Regarding the long-term reliability, the residual stress generated at the bonding interface between the glass substrates 2 and 3 and the sealing layer 5 is particularly affected. If the residual stress at the bonding interface is large, cracks and cracks are likely to occur in the sealing layer 5 and the glass substrates 2 and 3. In this embodiment, since the residual stress at the bonding interface is relaxed, the bonding strength of the sealing layer 5 and the hermetic sealing performance based thereon can be maintained over a long period of time. Therefore, it becomes possible to provide the solar cell 1 excellent in reliability with high reproducibility.

  The use of the sealing material of this embodiment and the glass member with a sealing material layer (glass substrate 3 having the sealing material layer 6) using the sealing material is limited to the production of a glass package for solar cells. Rather than a flat panel display device such as an organic EL display, plasma display panel, liquid crystal display device, etc., a glass package used for organic EL lighting using an organic EL element (consisting of two glass substrates and a sealing layer) The present invention can also be applied to a package), a glass member (building material) such as a sealed body of electronic parts and vacuum pair glass.

  Next, specific examples of the present invention and evaluation results thereof will be described. In addition, the following description does not limit this invention, The modification | change in the form along the meaning of this invention is possible.

Example 1
In terms of mass%, Bi ₂ O ₃ 82.8%, B ₂ O ₃ 5.6%, ZnO 10.7%, Al ₂ O ₃ 0.5%, CeO ₂ 0.2%, Fe ₂ O ₃ 0. Bismuth glass frit having a composition of 1% and CuO 0.1% (average particle diameter = 1 μm, specific gravity = 7.2, DTA glass transition point = 356 ° C., DTA glass softening point = 410 ° C.), as a low expansion filler Cordierite powder (average particle size = 2 μm, specific gravity = 2.5), Fe ₂ O ₃ —Co ₂ O ₃ —Cr ₂ O ₃ black pigment (average particle size = 1 μm, specific gravity = 5.1) as a laser absorber. ), Hollow glass beads made of borosilicate glass as a hollow bead, Sphericel 110P8 (Potters Barotini, average particle size = 12 μm, specific gravity = 1.1, specific gravity of shell material = 2.6, space ratio = 58% ) Was prepared.

The above-mentioned bismuth-based glass frit 84.1% by mass, cordierite powder 10.0% by mass, black pigment 4.7% by volume, and hollow glass beads 1.2% by mass are mixed to form a sealing material (thermal expansion coefficient: 75 × 10 ⁻⁷ / ° C.). Ratio of total volume B of voids of hollow glass beads to total volume A of glass frit, cordierite powder, black pigment and hollow glass beads (B / A × 100 [%] (porosity of sealing material)) Is 3.5%. Next, 90% by mass of the sealing material was mixed with 10% by mass of the vehicle to prepare a sealing material paste. The sealing material paste was diluted with a solvent so that the viscosity became 130 Pa · s. The vehicle was prepared by dissolving 5% by mass of ethyl cellulose as a binder component in 95% by mass of a solvent composed of 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate.

Next, the sealing material paste is applied to the outer peripheral region of a second glass substrate (dimensions: 100 × 100 × 0.5 mmt) made of soda lime glass (thermal expansion coefficient: 87 × 10 ⁻⁷ / ° C.). After applying by screen printing so as to be 1 mm, it was dried at 120 ° C. for 10 minutes. Subsequently, the sealing material layer having a film thickness of 35 μm was formed by firing at 460 ° C. for 10 minutes in a firing furnace.

  The second glass substrate having the sealing material layer described above and a first glass substrate (a glass substrate having the same composition and shape as the second glass substrate) were stacked. Next, the sealing material layer is irradiated with a laser beam having a wavelength of 940 nm and an output of 13 W at a scanning speed of 10 mm / s through the second glass substrate to melt and quench and solidify the sealing material layer. The substrate and the second glass substrate were sealed. The processing temperature of the sealing material layer was 503 ° C. (measured with a radiation thermometer).

The glass panel thus obtained was evaluated for hermetic sealing properties after the initial sealing stage and the thermal cycle test (TCT). The thermal cycle test (TCT) was performed by repeating −200 ° C. × 30 minutes → 85 ° C. × 30 minutes as one cycle and repeating this 200 times. The airtight sealing performance was evaluated by a helium leak test, and it was determined that the airtightness was sufficient when the measured value was 10 ⁻⁹ Pa · m ³ / s or less. As a result, it was confirmed that the glass panel according to Example 1 has sufficient airtightness not only in the initial stage of sealing but also after the thermal cycle test. In addition, when the cross section of the sealing layer was observed by SEM, it was confirmed that the shape (hollow shape) of the hollow glass beads was maintained even after laser sealing.

  Next, in order to confirm the effect of reducing the residual stress by the sealing material of Example 1 (sealing material containing hollow glass beads), the following tests were performed. First, after applying the above-mentioned sealing material paste to a soda lime glass substrate (dimensions: 50 × 10 × 0.55 mmt), baking is performed under the same conditions as in the baking step described above, so that the shape is 30 × 1 mm and the film thickness. Formed a sealing material layer of 35 μm. After placing a soda lime glass substrate on the sealing material layer, laser sealing was performed under the same conditions as in the laser sealing step described above, thereby producing a joined sample for stress measurement. However, the output of the laser beam was 12 W, 13 W, and 14 W, and in each case, laser sealing was performed to prepare a joined body sample.

  The strain of each sample thus obtained was measured from the cross-sectional direction, and the residual stress value was calculated from the strain value. The results are shown in Table 1 and FIG. Also, laser sealing was performed under the same conditions as in Example 1 for a sealing material layer (Comparative Example 1) formed using a sealing material that does not contain hollow glass beads (the composition is shown in Table 2 described later). As a result, a joined body sample for stress measurement was produced. Table 1 and FIG. 8 also show the measurement results of the joined body sample according to Comparative Example 1.

  As is apparent from Table 1 and FIG. 8, the joined body sample using the sealing material containing the hollow glass beads of Example 1 is the joined body sample of Comparative Example 1 using the sealing material containing no hollow glass beads. It can be seen that the residual stress is reduced at each sealing temperature. Therefore, by applying the glass package of Example 1 to produce a solar cell, the reliability can be maintained for a long period.

(Example 2)
Example 1 except that the same glass frit, low expansion filler, laser absorber, and hollow glass beads as in Example 1 were used and these were mixed at the compounding ratio shown in Table 2 to produce a sealing material. A glass package was produced in the same manner as described above (laser light output was 13 W). The hermetic sealing property of this glass package was measured in the same manner as in Example 1. The results are shown in Table 2. As is clear from Table 2, it was confirmed that the glass package of Example 2 had sufficient airtightness not only in the initial sealing stage but also after the thermal cycle test as in Example 1. . In addition, it was confirmed that the residual stress at the bonding interface was also reduced as in Example 1.

(Examples 3 to 4)
Example 1 except that the same glass frit, low expansion filler, laser absorber, and hollow glass beads as in Example 1 were used and these were mixed at the compounding ratio shown in Table 2 to produce a sealing material. A glass package was produced in the same manner as described above (laser light output was 13 W). In Example 3, the porosity of the sealing material is 7%, and in Example 4, the porosity of the sealing material is 10%. The hermetic sealing properties of these glass packages were measured in the same manner as in Example 1. The results are shown in Table 2.

  Next, a joined body sample for stress measurement was prepared in the same manner as in Example 1 except that the sealing materials of Example 3 and Example 4 were used. In addition, about the sealing material of Example 3, the conjugate | zygote sample was produced for the output of the laser beam as 13W. As for the sealing material of Example 4, joined body samples were prepared with laser light outputs of 12.5 W, 13 W, and 13.5 W, respectively. The distortion of these joined body samples was measured in the same manner as in Example 1, and the residual stress value was calculated from those values. The results are shown in Table 3.

  As is apparent from Tables 2 and 3, when a sealing material having a porosity of 7% and 10% was used, the residual stress was reduced, and the glass package was hermetically sealed. The stopping property is also maintained. Therefore, it can be seen that even when hollow glass beads are blended in the sealing material, a sufficient hermetic sealing property can be secured.

  DESCRIPTION OF SYMBOLS 1 ... Solar cell, 2 ... 1st glass substrate, 2A ... 1st element area | region, 2B ... 1st sealing area | region, 3 ... 2nd glass substrate, 3A ... 2nd element area | region, 3B ... 2nd 4 ... Battery element part, 4A, 4B ... Element structure, 5 ... Sealing layer, 6 ... Sealing material layer, 7 ... Laser beam.

Claims (10)

  Sealing glass made of low melting point glass, low expansion filler in the range of 5 to 25% by mass ratio, laser absorber in the range of 1 to 10%, and hollow beads in the range of 0.5 to 7% A sealing material for laser sealing, comprising:   2. The sealing material for laser sealing according to claim 1, wherein the hollow beads are hollow glass beads made of a glass material selected from borosilicate glass, aluminosilicate glass, and soda lime glass.   The sealing material for laser sealing according to claim 1 or 2, wherein the hollow beads have an average particle diameter in the range of 1 to 15 µm.   The hollow beads have a ratio of total volume B of pores in the hollow beads to total volume A of the sealing glass, the low expansion filler, the laser absorber, and the hollow beads (B / A × 100 [ %]) Has pores in the range of 1 to 20%, the sealing material for laser sealing according to any one of claims 1 to 3. The low-melting-point glass is made of bismuth-based glass containing Bi ₂ O _{3 in} the range of 70 to 90% by mass, ZnO in the range of 1 to 20%, and B ₂ O ₃ in the range of 2 to 18%. The sealing material for laser sealing according to any one of claims 1 to 4, wherein:   The low expansion filler is at least one selected from silica, alumina, zirconia, zirconium silicate, aluminum titanate, mullite, cordierite, eucryptite, spodumene, zirconium phosphate compound, tin oxide compound, and quartz solid solution. The sealing material for laser sealing according to any one of claims 1 to 5, wherein the sealing material comprises a seed. A glass substrate provided with a sealing region;
A sealing material layer provided on the sealing region of the glass substrate and comprising a fired layer of the sealing material for laser sealing according to any one of claims 1 to 6. A glass member with a sealing material layer.   The said sealing material layer has thickness of the range of 20-100 micrometers, The glass member with the sealing material layer of Claim 7 characterized by the above-mentioned. A first glass substrate having a first surface with a first sealing region;
It has a 2nd surface provided with the 2nd sealing field corresponding to the 1st sealing field, and it arranges so that the 2nd surface may counter the 1st surface of the 1st glass substrate A second glass substrate,
A solar cell element portion provided between the first glass substrate and the second glass substrate;
It is formed between the first sealing region of the first glass substrate and the second sealing region of the second glass substrate so as to seal the solar cell element part. A solar cell comprising: a sealing layer comprising a melt-fixed layer of the sealing material for laser sealing according to any one of claims 1 to 6. Providing a first glass substrate having a first surface with a first sealing region;
The first sealing region is formed on the second sealing region corresponding to the first sealing region of the first glass substrate, and on the second sealing region. Preparing a second glass substrate having a second surface comprising a sealing material layer comprising a fired layer of the laser sealing sealing material;
Laminating the first glass substrate and the second glass substrate via the sealing material layer such that the first surface and the second surface are opposed to each other;
The sealing material layer is irradiated with laser light through the first glass substrate or the second glass substrate, and the sealing material layer is melted to form the first glass substrate and the second glass substrate. And a step of forming a sealing layer for sealing the solar cell element portion provided therebetween.

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