JP6914548B2 - Dye-sensitized solar cells and their manufacturing methods - Google Patents

Description

The present invention relates to a dye-sensitized solar cell and a method for manufacturing the same.

Compared to silicon solar cells, dye-sensitized solar cells (DSCs) can generate electricity more efficiently at low illuminance, and can be produced at low cost and with low energy, so they are stand-alone devices with low power consumption. It has begun to be used as a power source. Among them, the monolithic type dye-sensitized solar cell can be formed by a printing pattern on one substrate, and is superior in cost and mass productivity as compared with other major W type and Z type, for example, patent documents. Proposed in 1.

Japanese Unexamined Patent Publication No. 2010-15761

FIG. 5 is a cross-sectional view showing a cell structure of a typical dye-sensitized solar cell 9 of the prior art. The dye-sensitized solar cell 9 is a monolithic type, and at least a transparent electrode 92 is formed on a flat glass substrate 91 having translucency with respect to the wavelength of the solar cell on the light incident side, and the transparent electrode 92 is formed on the flat glass substrate 91. A photoelectric conversion layer 93 and a porous insulating layer 94 dye-adsorbed on a porous semiconductor are laminated, a back electrode 95 and a catalyst layer 96 are laminated on the photoelectric conversion layer 93, and a sealing material 97 made of an adhesive synthetic resin or the like is applied around the layers. Then, it is sealed with a flat plate cover glass 98, and the internal space is filled with the electrolytic solution 99.

When water enters the electrolytic solution 99, the efficiency of the monolithic dye-sensitized solar cell 9 configured as described above progresses. Therefore, reliable sealing with the sealing material 97 is required. In general, the sealing width W1 is relative to the gap H1 between the glass substrate 91 and the cover glass 98 due to the prevention of evaporation of the solvent of the electrolytic solution 99 by the various sealing materials 97 and the invasion prevention property of the above-mentioned moisture. The aspect ratio W1 / H1 of was required to be at least 100 times or more.

Here, the photoelectric conversion layer 93, the porous insulating layer 94, the back electrode 95, and the like are formed by printing, and the total thickness is 50 to 70 μm. Therefore, the sealing width W needs to be at least 5 to 7 mm. Further, since it is necessary to apply the sealing material 97 thickly to the above-mentioned 50 to 70 μm or more, it is generally applied by a dispenser, but the above-mentioned width of 5 to 7 mm and productivity can be improved. It takes a long time to apply a large number of cells to increase the number of cells. Further, when the sealing width W becomes wide, there is a problem that the area used for power generation is relatively small and the panel becomes large in order to secure the required power generation amount.

An object of the present invention is to improve the reliability of sealing and improve the productivity while narrowing the width of the sealing material and relatively expanding the area to be used for power generation. It is an object of the present invention to provide a dye-sensitized solar cell capable of being produced and a method for producing the same.

In the dye-sensitized solar cell of the present invention, at least a transparent electrode layer, a porous semiconductor layer, a porous insulating layer, and a back electrode layer are sequentially laminated on a flat substrate having translucency with respect to the wavelength of the solar cell. The porous semiconductor layer is dye-adsorbed, and the cover is engraved in a monolithic dye-sensitized solar cell in which an electrolytic solution is sealed in an internal space formed between the cover and the substrate. A recess for forming the internal space and a sealing material for sealing the peripheral edge of the recess with the substrate are provided , and a plurality of cells are formed on one of the substrates, and these cells are formed. between and / or outer periphery the sealing material is applied, the cell side and / or outer peripheral side of the coating pattern, and wherein Rukoto excess of the sealing material are grooves for flowing formation do.

Further, in the method for manufacturing a dye-sensitized solar cell of the present invention, at least a transparent electrode layer, a porous semiconductor layer, a porous insulating layer and a back electrode layer are formed on a flat substrate having transparency with respect to the wavelength of the solar cell. In a method for manufacturing a monolithic dye-sensitized solar cell, which is sequentially laminated, the porous semiconductor layer is dye-adsorbed, and an electrolytic solution is sealed in an internal space formed between the cover and the substrate. , A step of engraving a recess forming the internal space in the cover, a step of forming a sealing material on the peripheral edge of the recess, and a step of solidifying the sealing material and joining the cover and the substrate. look including bets, a plurality of cells are formed on one of said substrate, between those cells and / or outer periphery the sealing material is applied to the cell side and / or outer peripheral side of the application pattern It is characterized by further comprising a step of forming a concave groove for the excess portion of the sealing material to flow in.

According to the above configuration, at least a transparent electrode layer, a porous semiconductor layer, a porous insulating layer, and a back electrode layer are sequentially laminated on a flat substrate having transparency with respect to the wavelength of the solar cell on the light incident side. In a dye-sensitized solar cell in which the porous semiconductor layer is dye-adsorbed and an electrolytic solution is sealed in an internal space formed between the cover and the substrate, the formation of the internal space has been conventionally performed. It is realized by a recess formed by engraving the side of the cover, instead of being formed by a pair of flat plates and a wall of a sealing material formed on the peripheral edge.

Specifically, it is a monolithic dye-sensitized solar cell in which at least the transparent electrode layer, the porous semiconductor layer on which the dye is adsorbed, the porous insulating layer, and the back electrode layer are sequentially laminated on a flat substrate, and the patterns thereof are formed. On the side of the cover that is not formed, the portions corresponding to those patterns are engraved to a depth equal to or more than the total thickness of them by sandblasting, etching, or the like to form the recesses. Then, the peripheral edge portion between the substrate and the cover is joined with a sealing material to airtightly seal the internal space formed by the recess.

Therefore, since the height of the internal space, that is, the film thickness is secured by the engraving depth of the cover, the thickness of the sealing material can be made extremely thin. As a result, the width of the encapsulant can be narrowed, the frame can be narrowed, the number of solar cell panels taken from the substrate can be increased, and the amount of power generation per the same substrate area can be increased. Further, in order to increase the power generation efficiency, even if the film thickness of the printing layer becomes thicker, such as forming a porous light reflecting layer on the porous semiconductor layer, the concave portion of the cover may be engraved accordingly. .. In addition, the encapsulant may be applied thinly with a narrow width. Especially when the solar cell is multi-chamfered and produced, the coating of the encapsulant, which becomes a bottleneck, is changed from the conventional dispense to screen printing. It is possible to improve the reliability of sealing and to realize a significant improvement in productivity.

Also , in a panel of a dye-sensitized solar cell in which a plurality of cells are formed on one substrate so that they can be connected in series or in parallel with each other or can be mass-produced at the same time, the cells of the panel and / or an outer periphery, when further sealed with a sealing material, previously formed a concave groove on the cell side and / or outer peripheral side of the coating pattern of the sealing material.

As a result, when the substrate and the cover are crimped together, the excess encapsulant flows into the concave groove and does not exude to the inside of the concave groove, so that the encapsulant undesirably exudes into the cell. This can be prevented. Further, since the sealing material is thinned, the internal stress is small and the peel strength is improved.

Further, in the dye-sensitized solar cell of the present invention, the plurality of cells are separated from each other and used, and a break line is formed in the concave groove portion from the outside of the cover.

Furthermore, in the method for manufacturing a dye-sensitized solar cell of the present invention, the plurality of cells are separated from each other and used, and the recessed groove portion further includes a step of forming a break line from the outside of the cover. It is characterized by that.

According to the above configuration, when a plurality of cells are formed on one substrate and a concave groove into which excess sealing material flows is formed between the cells and / or on the outer periphery, the opposite of the cover. A break line is formed from the side surface.

Therefore, it is possible to easily and surely separate the individual cells by utilizing the thin portion formed by the break line and the concave groove. Further, against an impact when the cell is separated from the break line, peeling or the like can be prevented due to the thickness of the sealing material that has flowed into the concave groove.

Further, the dye-sensitized solar cell of the present invention is characterized in that a glass frit is used as the sealing material between the cells and / or on the outer periphery.

According to the above configuration, a glass frit paste is printed and formed in advance on the sealing and bonding portion of the glass cover by screen printing or the like, and this glass cover is attached to a glass substrate and irradiated with laser light, or By raising the temperature of the whole to 300 to 450 ° C. to melt and fuse the glass frit, the hardness is increased and strong adhesive strength can be obtained. As a result, it is possible to obtain the effects of completely preventing the electrolyte solvent from scattering and sealing the moisture, and it is also possible to reliably break.

In this regard, conventionally, since there is a gap of 50 to 70 μm between the glass substrate and the cover glass as described above, the application of the glass frit paste can be overprinted many times by screen printing, or the time required by the dispenser. Even if the temperature of the glass was further increased to melt the glass frit, air bubbles could easily enter due to the wide gap, and good sealing was difficult.

As described above, the dye-sensitized solar cell of the present invention and the method for manufacturing the same include at least a transparent electrode layer and a porous semiconductor layer on a flat substrate having translucency with respect to the wavelength of the solar cell on the light incident side. A monolithic type in which a porous insulating layer and a back electrode layer are sequentially laminated, the porous semiconductor layer is dye-adsorbed, and an electrolytic solution is sealed in an internal space formed between the cover and the substrate. In the dye-sensitized solar cell, the formation of the internal space is not formed by a pair of conventional flat plate substrates and a wall of a sealing material formed at the peripheral portion, but is formed by engraving the side of the cover. Realized in the recess.

Therefore, since the height of the internal space, that is, the total film thickness of each layer is secured by the engraving depth of the cover, the thickness of the sealing material can be made extremely thin. As a result, the width of the encapsulant can be narrowed, the frame can be narrowed, the number of solar cell panels taken from the substrate can be increased, and the amount of power generation per the same substrate area can be increased. Further, in order to increase the power generation efficiency, even if the film thickness of the printing layer becomes thicker, such as forming a porous light reflecting layer on the porous semiconductor layer, the concave portion of the cover may be engraved accordingly. .. In addition, the encapsulant may be applied thinly with a narrow width. Especially when the solar cell is multi-chamfered and produced, the coating of the encapsulant, which becomes a bottleneck, is changed from the conventional dispense to screen printing. It is possible to improve the reliability of sealing and to realize a significant improvement in productivity.

It is sectional drawing which shows the cell structure of the dye-sensitized solar cell which concerns on one Embodiment of this invention. It is sectional drawing which shows the part of FIG. 1 enlarged. It is a front view of the solar cell panel including the dye-sensitized solar cell of FIG. 1 and FIG. It is sectional drawing which shows the part of FIG. 3 enlarged. It is sectional drawing which shows the cell structure of the typical dye-sensitized solar cell of the prior art.

FIG. 1 is a cross-sectional view showing a cell structure of a dye-sensitized solar cell 1 according to an embodiment of the present invention. FIG. 1 emphasizes the thickness direction in order to make the structure easier to understand. The dye-sensitized solar cell 1 is a monolithic type, and at least a transparent electrode layer 12 is formed on a flat plate substrate 11 having translucency with respect to the wavelength of the solar cell on the light incident side, and a dye is formed on the transparent electrode layer 12. The adsorbed porous semiconductor layer and the porous insulating layer 13 are laminated, and the back electrode layer 14 such as carbon is laminated on the laminated surface, the sealing material 15 is applied to the periphery, and the inside is sealed by the cover 16. The space 17 is filled with the electrolytic solution 18.

It should be noted that according to the dye-sensitized solar cell 1 of the present embodiment and the method for manufacturing the same, the cover 16 is engraved, and the recess 19 forming the internal space 17 is formed by the engraving. That is. The engraving depth is a dimension predetermined from the thickness of the transparent electrode 12 plus the printing thickness of the porous semiconductor layer, the porous insulating layer 13, and the back electrode layer 14 formed by screen printing or the like. Only deeply set. When the cover 16 is made of a glass plate, the step of engraving the recess 19 can be easily performed by etching the flat glass plate with a hydrogen fluoride-based etching solution or sandblasting. Since the cover 16 is on the back side of the dye-sensitized solar cell 1, there is no problem even if the recess 19 is a rough surface due to sandblasting or a non-smooth surface due to etching.

Specifically, a porous semiconductor is formed by using fine particle titanium oxide paste or the like on a substrate 11 such as glass on which a transparent electrode layer 12 sputtered with commercially available FTO (fluorine-doped tin oxide) or ITO (indium-doped tin oxide) is formed. A step of sequentially screen-printing the porous insulating layer 13 with a layer and fine particle zirconia paste and the back electrode layer 14 with a conductive carbon paste or the like is performed, and the back electrode layer 14 is immersed in a dye solution to adsorb the dye on the porous semiconductor layer. A step of engraving the recess 19 in the cover 16 of a glass plate or the like and a step of screen-printing the sealing material 15 on the peripheral edge 20 of the recess 19 are performed. A step of bonding the sides and solidifying the sealing material 15 such as an adhesive resin or glass frit with ultraviolet rays, heating, a laser or the like is performed. After that, the electrolytic solution 18 is filled in the internal space 17, and the filling port is closed.

As the sealing material 15, a photocurable acrylate resin, UV, an epoxy-modified acrylate resin curable with heat, specifically, a resin such as TB3035B or TB3118 manufactured by ThreeBond Co., Ltd. is cured, or a low melting point glass frit is used. This can be achieved by applying and laser fusing. In the dye adsorption, fine particles are obtained by immersing and drying a ruthenium dye such as N719 or N749 black dye having a carboxyl group, a coumarin dye, a polyfin dye or the like in a solution in which an organic solvent such as dimethylformamide or methanol is dissolved. These dyes can be adsorbed on the surface of titania. As the electrolytic solution 18, a solvent such as acetonitrile or methoxypropionitrile in which potassium iodide, dimethylpropioimidazolium iodine or the like is dissolved, and tertiary butylamine or the like is added can be used. In the case of high-temperature sealing with glass frit, the dye adsorption step on the porous semiconductor layer may be performed after the bonding step. Further, in order to improve the power generation efficiency, a reflective layer to which reflective particles such as titanium oxide having a size of about 200 to 1000 nm is added may be printed and formed on the porous semiconductor layer.

As described above, according to the dye-sensitized solar cell 1 of the present embodiment and the method for manufacturing the same, in the monolithic dye-sensitized solar cell, at least the transparent electrode layer 12 and the dye-adsorbed porous material are placed on the substrate 11. Quality The semiconductor layer, the porous insulating layer 13, and the back electrode layer 14 are formed, but on the side of the cover 16 where they are not formed, the portion corresponding to those patterns is equal to or greater than the total thickness of each layer. Since the recess 19 is formed by engraving to the depth of, the thickness of the sealing material 15 can be made extremely thin.

FIG. 2 is an enlarged cross-sectional view showing a cell edge portion of the dye-sensitized solar cell 1 of FIG. As shown in FIG. 2, by engraving the recess 19, the gap H2 between the peripheral edge 20 of the recess 19 and the substrate 11 can be made as close to 0 as possible. For example, the sealing material 15 can be screen-printed. It can be controlled with the minimum film thickness that can be formed, about 3 to 5 μm. Specifically, if a small amount of spacer particles of about 5 μm is added to the sealing material 15 and then printed and pressure-bonded, the gap H2 can be managed in μm units in an extremely stable manner.

Therefore, even if the aspect ratio W2 / H2 with the width W2 of the joint portion (peripheral portion 20) is 140 times that can prevent evaporation of the solvent of the electrolytic solution 18 and obtain a sufficient effect on moisture resistance, the width W2 Can be as narrow as 0.7 mm. As a result, the frame can be narrowed to increase the number of panels of the solar cell (1) taken from the substrate 11, and the amount of power generation per the same substrate area can be increased. Further, the sealing material 15 may be applied thinly (H2) with a narrow width W2 (it is not necessary to apply a thick coating), and particularly when the solar cell (1) is multi-chamfered and produced, it becomes a bottleneck. The method of applying the stop material can be changed from the conventional dispense to screen printing, and it is possible to improve the reliability of sealing and greatly improve the productivity. The monolithic dye-sensitized solar cell has the highest cost and mass productivity, and in the present embodiment, the reliability and productivity of the monolithic dye-sensitized solar cell can be further improved, which is suitable.

Further, it should be noted that in the dye-sensitized solar cell 1 of the present embodiment, as shown in an enlarged manner in FIG. 2, the peripheral edge portion 20 of the recess 19 is roughened. In particular, when the recess 19 is formed by sandblasting, it is only necessary to perform a sandblasting process on the entire surface of the cover 16 when the engraving is completed or at the end of the engraving. By doing so, the surface area (creeping distance) of the peripheral edge portion 20 with respect to the sealing material 15 can be increased, the bonding strength can be increased, and the solvent of the electrolytic solution 18 can be prevented from evaporating and the moisture resistance can be improved. A high effect can be obtained.

FIG. 3 is a front view of the solar cell panel 3 including the dye-sensitized solar cell 1 described above. Although the dye-sensitized solar cell 1 of FIGS. 1 and 2 is described as a single cell, in many cases, a plurality of cells (1) are formed on one substrate 31 (11), and these cells are formed. Used in series and / or connected in parallel. On the other hand, when used in a single cell (1), for example, a 90 mm × 45 mm cell (1) is produced by multi-chamfering (24 chamfering) from a substrate 31 having a size of 400 mm × 300 mm.

Then, a plurality of cells (1) are formed on one substrate 31 (11), and the sealing material 15 is applied between the cells (1) and / or on the outer periphery of the substrate 31 (11). If this is the case, it should be noted that in the present embodiment, recessed grooves 33, 34 into which the surplus of the sealing material 15 flows are formed on the cell side and / or the outer peripheral side of the coating pattern 32. It is to be done. FIG. 4 is an enlarged cross-sectional view showing a part of FIG. In the example of FIG. 3, the coating pattern 32 is not formed between the cells (1), but is formed on the outer periphery of the substrate 31 (11). Further, in the example of FIG. 3, the concave groove 33 is formed on the inner (cell) side and the concave groove 34 is formed on the outer side of the coating pattern 32, but the size of the substrate 31 (11) and the cell (1) are formed. The outer concave groove 34 is optional as long as there is no balance between the size and the like, or problems in appearance and performance as a solar cell.

With this configuration, when the substrate 31 (11) and the cover 16 are crimped together, the excess sealing material (32) flows into the recesses 33 and 34, and the recesses 33 and 34 flow into the recesses 33 and 34. Since it does not exude more inward, it is possible to prevent the sealing materials 33 and 34 from undesirably exuding into the cell (1). Further, since the sealing material (32) is thinned, the internal stress is small and the peel strength is improved.

On the other hand, when the panel of FIG. 3 is multi-chamfered as described above, since the plurality of cells (1) are separated from each other and used, the outer concave groove 34 portion is covered as shown in FIG. A break line 35 may be formed from the outside of 16. With this configuration, a plurality of cells (1) are formed on one substrate 31 (11), and a recessed groove into which excess sealing materials 15 and 32 flow into the cells and / or the outer periphery. When the 33 and 34 are formed, the individual cells (1) can be easily and surely separated by utilizing the thin portion formed by the break line 35 from the opposite surface of the cover 16 and the concave groove 34. It can be performed. Further, against an impact when the cell (1) is separated from the break line 35, peeling or the like can be prevented due to the thickness of the sealing material 32 flowing into the concave groove 34.

In that case, glass frit is used as the sealing material 32, and the glass frit can be sealed by irradiating it with a laser beam to solidify it. On the other hand, if the glass frit is solidified, the hardness is high, and the break line 35 You can surely make a break.

Here, a dye-sensitized solar cell that seals using a concavely formed substrate is shown in JP-A-2010-123556 and JP-A-2004-362793. According to these conventional techniques, porous titanium oxide, dye, electrolytic solution, etc. are made into a rubber-like gel material with a polymer absorber, and therefore, although strict sealing is not devised, recesses and ribs are used. The combination with the upright wall is shown.

However, in this conventional technique, both substrates including the transparent conductive substrate are formed into irregularities, and both are fitted to each other. Therefore, not only an expensive molding die is required, but also the molding is performed at a high temperature. Therefore, due to thermal expansion and contraction of the material, sink marks, etc. Is extremely difficult to manage in units of μm. That is, it can be considered that these conventional techniques narrow the frame width by making the horizontal gap vertical, rather than narrowing the frame width by making the gap between the substrates close to zero.

Further, in these conventional techniques, a transparent electrode, a porous semiconductor layer, or the like must be formed in a pattern in the concave portion of the concave base material, and a mass-producible method such as screen printing cannot be used, which is a very special masking. Therefore, the transparent electrode must be formed by spatter formation, spraying of a porous semiconductor layer, or the like, which is poor in mass productivity and difficult to manufacture at low cost. Therefore, the mass productivity and cost are completely different from those of the present embodiment in which the cover 16 is engraved and formed by etching or sandblasting.

1 Dye-sensitized solar cell (cell)
11 Substrate 12 Transparent electrode layer 13 Porous semiconductor layer and porous insulating layer 14 Back electrode layer 15 Encapsulant 16 Cover 17 Internal space 18 Electrolyte 19 Recession 20 Peripheral part 3 Solar cell panel 31 Substrate 32 Coating pattern 33, 34 Concave Groove 35 break line

Claims (5)

At least a transparent electrode layer, a porous semiconductor layer, a porous insulating layer, and a back electrode layer are sequentially laminated on a flat substrate having translucency with respect to the wavelength of a solar cell, and the porous semiconductor layer is dye-adsorbed. Further, in a monolithic dye-sensitized solar cell in which an electrolytic solution is sealed in an internal space formed between the cover and the substrate.
A recess that forms the internal space by engraving the cover,
A sealing material for sealing the peripheral edge of the recess with the substrate is provided .
A plurality of cells are formed on one of the substrates, the sealing material is applied between the cells and / or the outer periphery thereof, and the sealing material is applied to the cell side and / or the outer peripheral side of the coating pattern. dye-sensitized solar cell surplus characterized that you have been recessed groove the inflowing formed of wood. Wherein the plurality of cells are used to disconnect each other, wherein the groove portion, the dye-sensitized solar cell of claim 1, wherein the break line from the outside of the cover is formed. The dye-sensitized solar cell according to claim 1 or 2 , wherein a glass frit is used as the sealing material between the cells and / or on the outer periphery. At least a transparent electrode layer, a porous semiconductor layer, a porous insulating layer, and a back electrode layer are sequentially laminated on a flat substrate having translucency with respect to the wavelength of a solar cell, and the porous semiconductor layer is dye-adsorbed. Further, in a method for manufacturing a monolithic dye-sensitized solar cell in which an electrolytic solution is sealed in an internal space formed between a cover and the substrate.
A step of engraving a recess forming the internal space in the cover,
The step of forming a sealing material on the peripheral edge of the recess and
Look including the step of bonding the cover and the substrate by solidifying the sealing material,
A plurality of cells are formed on one of the substrates, the encapsulant is applied between the cells and / or the outer periphery thereof, and the encapsulant is applied to the cell side and / or the outer periphery of the coating pattern. A method for manufacturing a dye-sensitized solar cell, which further comprises a step of forming a concave groove for the surplus of the above. The dye-sensitized solar cell according to claim 4, wherein the plurality of cells are used so as to be separated from each other, and the recessed groove portion further includes a step of forming a break line from the outside of the cover. Production method.

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