GLASS COMPOSITION CO-FIREABLE WITH TITANIA FOR SEALING LARGE-AREA DYE-SENSITIZED SOLAR CELL

Abstract

The present invention relates to a glass material for sealing a large-area dye-sensitized solar cell and, more specifically, to a glass material capable of binding to a large area uniformly and very strongly without reacting with en electrolyte. According to the present invention as described above, the glass material is expected to have effects of uniformly sealing a dye-sensitized solar cell, securing stable chemical properties against a reaction with an electrolyte, and having physical strength suitable for large-area binding, and thus can improve reliability and lifetime of solar cell products.

Claims

1. A glass composition for sealing a dye-sensitized solar cell, comprising (P.sub.2O.sub.5, +ZnO)V.sub.2O.sub.5TeO.sub.2, wherein (P.sub.2O.sub.5+ZnO) are present in 50 to 65 mol %, V.sub.2O.sub.5 is present in 30 to 45 mol %, TeO.sub.2 is present in 5 to 20 mol %, V.sub.2O.sub.5/TeO.sub.2 has a value of 2 to 6 based on a molar ratio, and at least one selected from Al.sub.2O.sub.3, B.sub.2O.sub.3 and Sb.sub.2O.sub.3 is comprised in an amount more than 0 mol % and less than or equal to 10 mol %.

2. The glass composition for sealing a dye-sensitized solar cell according to claim 1, wherein the at least one selected from Al.sub.2O.sub.3, B.sub.2O.sub.3 and Sb.sub.2O.sub.3 partly replaces the (P.sub.2O.sub.5 +ZnO).

3. The glass composition for sealing a dye-sensitized solar cell according to claim 1, which has a firing temperature of 400 to 500 C.

4. A paste for sealing a dye-sensitized solar cell, comprising: the glass composition according to claim 1; and an organic vehicle.

Description

BRIEF DESCRIPTION OF DRAWING

[0019] FIG. 1 is a phase diagram of a three-component system based on observations of a formation region of (P.sub.2O.sub.5+ZnO)V.sub.2O.sub.5TeO.sub.2 based glass.

MODE FOR CARRYING OUT INVENTION

[0020] Hereinafter, the embodiments of the present disclosure are described in detail with reference to the accompanying drawing. The embodiments disclosed below are provided for illustrative purposes to give a full understanding of the present disclosure to those having ordinary skill in the technical field to which the present disclosure belongs. Therefore, the present disclosure is not limited to the disclosed embodiments and may be embodied in other different forms.

[0021] First, a glass composition for sealing a dye-sensitized solar cell according to an exemplary embodiment of the present disclosure is described in detail.

[0022] In the present disclosure, firing temperature refers to the temperature for softening or metaling a glass composition during a sealing process.

[0023] FIG. 1 shows is a phase diagram of a three-component system (P.sub.2O.sub.5+ZnO)V.sub.2O.sub.5TeO.sub.2 based glass and a glass composition according to an exemplary embodiment of the present disclosure.

[0024] The glass composition for sealing a dye-sensitized solar cell contains (P.sub.2O.sub.5+ZnO)V.sub.2O.sub.5TeO.sub.2 based glass, and the (P.sub.2O.sub.5+ZnO)V.sub.2O.sub.5TeO.sub.2 based glass may contain 50 to 65 mol % of (P.sub.2O.sub.5+ZnO), 30 to 40 mol % of V.sub.2O.sub.5 and 5 to 20 mol % of TeO.sub.2.

[0025] The glass for sealing a dye-sensitized solar cell having the above component ratio is not susceptible to crystallization and phase separation, and because it does not contain alkali elements and transition metals that react with an electrolyte, it is not reactive with an electrolyte, and thus, is chemically stable, and it is physically strong due to high binding strength, and can be fired at the same temperature as the firing temperature of the dye-sensitized solar cell, facilitating the process.

[0026] The main cause of the high binding strength is sufficient flowability possessed due to low firing temperature as compared to other glass compositions, and can be further explained by the fact that additional components added in small amounts such as Al.sub.2O.sub.3, B.sub.2O.sub.3, Sb.sub.2O.sub.3, etc. control the thermal expansion coefficient to be similar to the thermal expansion coefficient of a substrate.

[0027] And, the main cause of the low firing temperature is the use of V.sub.2O.sub.5 and P.sub.2O.sub.5. It is because the conventional three-component system corresponds to materials all involved in having low temperature. To be more specific, V.sub.2O.sub.5 and P.sub.2O.sub.5 form a weak glass network structure and ZnO and TeO.sub.2 act to connect V.sub.2O.sub.5 to P.sub.2O.sub.5 between the two materials.

[0028] The firing temperature of the (P.sub.2O.sub.5+ZnO)V.sub.2O.sub.5TeO.sub.2 based glass may be 500 C. or lower, specifically 400 to 500 C. If the firing temperature is below 400 C., the fluidity and flowability of the glass composition may be low to some extent.

[0029] In the glass composition for sealing a dye-sensitized solar cell, the (P.sub.2O.sub.5+ZnO) may form a 2-dimensional or 3-dimensional basic structure in the glass as one of glass network formers. Glass containing the (P.sub.2O.sub.5+ZnO) may have superior fluidity of P.sub.2O.sub.5 and superior physically and chemically stable properties of ZnO at the same time when P.sub.2O.sub.5 and ZnO are combined at a specific ratio, as compared to glasses to which only P.sub.2O.sub.5 or ZnO is added. P.sub.2O.sub.5 has high fluidity due to low firing temperature as a weak glass network structure is formed in the glass. Therefore, the glass composition has low physical and chemical stability. ZnO forms a stronger bond than P.sub.2O.sub.5. It serves as a structure connector and former at the same time. When ZnO is combined with P.sub.2O.sub.5 at a specific ratio, both properties may be superior.

[0030] Specifically, the (P.sub.2O.sub.5+ZnO)V.sub.2O.sub.5TeO.sub.2 based glass according to an exemplary embodiment of the present disclosure may contain 50 to 65 mol % of (P.sub.2O.sub.5+ZnO). If the (P.sub.2O.sub.5+ZnO)V.sub.2O.sub.5TeO.sub.2 based glass contains the (P.sub.2O.sub.5+ZnO) in an amount less than 50 mol %, firing may be difficult due to decreased fluidity. And, if (P.sub.2O.sub.5+ZnO) is contained in an amount exceeding 65 mol %, chemical durability may be weak due to increased wettability. Accordingly, the above-described numerical range of the content of (P.sub.2O.sub.5+ZnO) has critical significance.

[0031] In the glass composition for sealing a dye-sensitized solar cell, V.sub.2O.sub.5 may serve as a network modifier to break the network structure, but a large amount of V.sub.2O.sub.5 may form a glass structure together with a certain amount of P.sub.2O.sub.5. Furthermore, the V.sub.2O.sub.5 acts to lower the firing temperature of glass, thereby facilitating the firing, and reduce the thermal expansion coefficient.

[0032] Specifically, the (P.sub.2O.sub.5+ZnO)V.sub.2O.sub.5TeO.sub.2 based glass according to an exemplary embodiment of the present disclosure may contain 30 to 40 mol % of V.sub.2O.sub.5.

[0033] When the P.sub.2O.sub.5V.sub.2O.sub.5(Sb.sub.2O.sub.3+ZnO) based glass contains less than 30 mol % of V.sub.2O.sub.5, wettability increases and the chemical durability of glass is decreased due to the relatively high fraction of P.sub.2O.sub.5. And, when the (P.sub.2O.sub.5+ZnO)V.sub.2O.sub.5TeO.sub.2 based glass contains more than 40 mol % of V.sub.2O.sub.5, the glass material to be produced may be physically weak or the firing temperature may be too low. Accordingly, the above-described numerical range of the content of V.sub.2O.sub.5 has critical significance.

[0034] In the glass composition for sealing a dye-sensitized solar cell, TeO.sub.2 is used as a portion of a network modifier. When TeO.sub.2 is present in small amounts, it serves as a network former of the (P.sub.2O.sub.5+ZnO)V.sub.2O.sub.5TeO.sub.2 based glass, thereby lowering the firing temperature of glass. Also, it may enhance bonding with the substrate through control of the thermal expansion coefficient. As the content increases, the softening point increases and the viscosity increases, causing phase separation and crystallization of glass.

[0035] Specifically, the (P.sub.2O.sub.5+ZnO)V.sub.2O.sub.5TeO.sub.2 based glass according to an exemplary embodiment of the present disclosure may contain 5 to 20 mol % of TeO.sub.2.

[0036] When the (P.sub.2O.sub.5+ZnO)V.sub.2O.sub.5TeO.sub.2 based glass contains less than 5 mol % of TeO.sub.2, the physical and chemical stability of glass is decreased. And, chemically, a reaction with oxygen, air or an electrolyte occurs, and physically, the crosslinking role of P.sub.2O.sub.5 and V.sub.2O.sub.5 is weakened, causing a problem with durability, which makes it difficult to be used as a glass material. In contrast, when TeO.sub.2 is contained in an amount exceeding 20 mol %, there are disadvantages that the viscosity of glass increases, leading to insufficient flowability at the temperature of 500 C. or below and making firing difficult, which may cause phase separation and crystallization of the glass material. Accordingly, the above-described numerical range of the content of TeO.sub.2 has critical significance.

[0037] The glass composition for sealing a dye-sensitized solar cell according to an exemplary embodiment of the present disclosure may further contain, in addition to the (P.sub.2O.sub.5+ZnO)V.sub.2O.sub.5TeO.sub.2 based glass, at least one selected from Al.sub.2O.sub.3, B.sub.2O.sub.3 and Sb.sub.2O.sub.3 in an amount more than 0 mol % and less than or equal to 10 mol %. The at least one selected from Al.sub.2O.sub.3, B.sub.2O.sub.3 and Sb.sub.2O.sub.3 may partly replace the (P.sub.2O.sub.5+ZnO).

[0038] Although the Al.sub.2O.sub.3, B.sub.2O.sub.3 and Sb.sub.2O.sub.3 may increase or decrease softening point by strengthening or weakening the network structure in the P.sub.2O.sub.5V.sub.2O.sub.5(Sb.sub.2O.sub.3+ZnO) based glass, they may serve to improve adhesion strength, chemical and physical stability, etc. When the Al.sub.2O.sub.3, B.sub.2O.sub.3 and Sb.sub.2O.sub.3 are contained in an amount exceeding 10 mol %, the firing temperature may be increased or decreased significantly due to the structural change of glass or phase separation and crystallization may occur.

[0039] Specifically, the glass composition for sealing a dye-sensitized solar cell according to an exemplary embodiment of the present disclosure may not further contain an additional transition metal such as Cr, Fe, Co, Ni, Mo or Bi. The transition metal may cause precipitation and elution in a dye-sensitized solar cell by reacting with an electrolyte. This may be the cause of reducing the durability of the glass for sealing a dye-sensitized solar cell.

[0040] The sealing of the dye-sensitized solar cell binds two substrates and the electrolyte used acts to block the contact with air, water and other contaminants. As the existing sealing material, the synthetic polymer material called Surlyn film is used. Although the film achieves stable binding and sealing for a single cell, as areas become larger, the binding strength becomes low and a process for uniform binding is unfavorable, and a contact area with oxygen or moisture increases and the reaction with an electrolyte is increased, making it difficult to use.

[0041] Accordingly, by using the glass appropriate for sealing a large-area dye-sensitized solar cell as a sealing material, physical durability can be improved and chemical and thermal durability can be ensured as compared to when the Surlyn film is used.

[0042] This glass can be used as a paste material for sealing a dye-sensitized solar cell, together with an organic vehicle.

[0043] Hereinafter, a glass manufacturing method according to another exemplary embodiment of the present disclosure is described in detail.

[0044] A method for preparing glass according to another exemplary embodiment of the present disclosure includes mixing 50 to 65 mol % of (P.sub.2O.sub.5+ZnO), 30 to 40 mol % of V.sub.2O.sub.5 and 5 to 20 mol % of TeO.sub.2 with an organic vehicle and firing at a predetermined firing temperature. The firing includes, but not limited to, molding the glass and the vehicle by heating, and for example, may be performed by processes including a screen printing process.

[0045] In addition, the firing may be also performed by various other methods. Subsequently, the molded glass and vehicle are molded by heating and melting at the predetermined firing temperature, and then cooled to complete the sealing process.

[0046] Because the glass does not contain alkali elements and additional transition metals such as Cr, Fe, Co, Ni, Mo or Bi, a maximum of reactable factors of the glass with an electrolyte is obviated. Therefore, high chemical and mechanical stability are achieved as elution and precipitation reactions are prevented.

[0047] When the Al.sub.2O.sub.3, B.sub.2O.sub.3 and Sb.sub.2O.sub.3 replace (P.sub.2O.sub.5+ZnO), the glass phase is stabilized, and it is possible to control the fluidity at a predetermined temperature. Accordingly, the process applicability can be improved by including the Al.sub.2O.sub.3, B.sub.2O.sub.3 and Sb.sub.2O.sub.3 in the (P.sub.2O.sub.5+ZnO)V.sub.2O.sub.5TeO.sub.2 based glass.

[0048] Hereinafter, specific examples according to the present disclosure are described in detail with reference to a drawing.

EXAMPLE

[0049] (P.sub.2O.sub.5+ZnO)V.sub.2O.sub.5TeO.sub.2 based glass was weighted for each sample according to the composition shown in Table 1. Although Al.sub.2O.sub.3 was selected from Al.sub.2O.sub.3, B.sub.2O.sub.3 and Sb.sub.2O.sub.3 as a specific example, other materials enumerated above can replace it within the range of compositional ratios presented in the present disclosure.

TABLE-US-00001 TABLE 1 Unit: mol % Glass Melting Firing sample P.sub.2O.sub.5 ZnO V.sub.2O.sub.5 TeO.sub.2 Al.sub.2O.sub.3 results results Note V.sub.2O.sub.5/TeO.sub.2 1 27.5 27.5 40 5 0 X Crystallized 8 2 32.5 32.5 30 5 0 Superior fluidity 6 3 37.5 37.5 20 5 0 4 4 25 25 40 10 0 X Crystallized 4 5 30 30 30 10 0 Superior fluidity 3 6 35 35 20 10 0 2 7 22.5 22.5 40 15 0 X Crystallized 2.7 8 27.5 27.5 30 15 0 2 9 32.5 32.5 20 15 0 1.3 10 20 20 40 20 0 X Crystallized 2 11 25 25 30 20 0 1.5 12 30 30 20 20 0 1 13 31.5 32.5 30 5 1 6 14 29.5 32.5 30 5 3 Superior physical 6 properties 15 27.5 32.5 30 5 5 6 16 29 30 30 10 1 3 17 27 30 30 10 3 Superior physical 3 properties 18 25 30 30 10 5 3 (Melting results: - excellent, - moderate, X - crystallized or unmelted) (Firing results: - excellent, - moderate, X - crystallized or unflowable)

[0050] The glass samples 1 to 18 were melted for 30 minutes by heating in the air at 1100 C. using an electric furnace, and then quenched to prepare glass. As a result, as shown in Table 1, all the glass samples containing (P.sub.2O.sub.5+ZnO), V.sub.2O.sub.5 and TeO.sub.2 were melted.

[0051] Subsequently, each of the samples 1 to 18 was processed into powder of 50 m or smaller to prepare glass powder, which was heated at 500 C. and fired for 30 minutes. As a result, as shown in Table 1, firing was performed well and superior fluidity and physical properties were achieved for 50 to 65 mol % of (P.sub.2O.sub.5+ZnO), 30 to 45 mol % of V.sub.2O.sub.5, 5 to 20 mol % of TeO.sub.2 and 1 or 3 mol % of Al.sub.2O.sub.3. The physical properties refer to the strength, chemical stability and adhesiveness of the glass.

[0052] In addition, superior firing results were achieved for the glass compositions with a V.sub.2O.sub.5/TeO.sub.2 molar ratio of 2 to 6. Superior firing results mean satisfactory processing by firing with good melting, without crystallization.

[0053] The description hereinabove provided has described the technical spirit of the present disclosure for illustrative purposes only, and various modifications, changes and substitutions can be made by those skilled in the art without departing from the nature of the present disclosure. Accordingly, the embodiments disclosed herein are provided to describe, but not intended to limit the technical spirit of the present disclosure, and the scope of the technical spirit of the present disclosure is not limited by these embodiments. The scope of protection of the present disclosure should be interpreted by the appended claims, and the full technical spirit within the scope in equivalence thereto shall be interpreted as being included in the scope of protection of the present disclosure.