Dye-sensitized Solar Cell And Method Of Preparing The Same

  • Published: Aug 7, 2008
  • Earliest Priority: Feb 02 2007
  • Family: 4
  • Cited Works: 0
  • Cited by: 15
  • Cites: 4
  • Additional Info: Full text

Description

DYE-SENSITIZED SOLAR CELL AND METHOD OF PREPARING THE SAME

Technical Field

[1] Apparatuses and methods consistent with the present invention relate to a dye- sensitized solar cell and a method of preparing the same, and more particularly, to a dye-sensitized solar cell which prevents an electrolyte from easily volatilizing from a sealing part, is resistant to an external shock or damage and is tightly sealed with strength to extend a life and improve durability while operating under harsh external environment, and a manufacturing method thereof. Background Art

[2] After a research team of Michael Gratzel at the Ecole Polytechnique Federale de

Lausanne (EPFL) in Switzerland developed a dye-sensitive nano particle titanium dioxide solar cell in 1991, lots of studies have been conducted on the field. The dye- sensitized solar cell requires significantly lower manufacturing costs than an existing silicon solar cell does, and can possibly replace an existing amorphous silicon solar cell. Unlike a silicon solar cell, the dye-sensitized solar cell is a photoelectrochemical solar cell which includes a dye molecule absorbing visible rays to generate an electron- hole pair and a transition metal oxide transferring a generated electron, as main materials.

[3] Generally, a unit cell configuration of the dye-sensitized solar cell includes upper and lower transparent substrates and conductive transparent electrodes respectively formed on a surface of the transparent substrates. A transition metal oxide porous layer which has a dye absorbed to a surface thereof is formed on a first conductive transparent electrode corresponding to a first electrode. A catalyst thin film electrode is formed on a second conductive transparent electrode corresponding to a second electrode. An electrolyte is injected between the porous electrode and the catalyst thin film electrode as the transition metal oxide, e.g., titanium dioxide (TiO2).

[4] To stably maintain the electrolyte injected between the first and second electrodes, the first and second electrodes having a thermoplastic high molecular film therebetween are heated and pressed to be coupled to each other. Thus, a particular space is formed between the first and second electrodes to inject and secure the electrolyte.

[5] However, the thermoplastic high molecular film does not have an elaborate configuration and easily deteriorates by intense sunlight, heat cycling, etc. The electrolyte minutely volatilizes by heat cycling during nighttime/daytime or in the winter/summer to lower efficiency of the solar cell, thereby ending the life ultimately. Also, due to a limit of a mechanical strength, the high molecular film is easily damaged by external shock and reduces the life of the solar cell, which is a critical problem in durability. Disclosure of Invention

Technical Problem

[6] Accordingly, it is an aspect of the present invention to provide a dye- sensitized solar cell which prevents an electrolyte from easily volatilizing from a sealing part, is resistant to an external shock or damage and is tightly sealed with strength to extend a life and improve durability while operating under harsh external environment, and a manufacturing method thereof. Technical Solution

[7] Additional aspects and/or advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the present invention.

[8] The foregoing and/or other aspects of the present invention are achieved by providing a dye-sensitized solar cell which has a first electrode including a transmissive layer having a porous layer with a dye in a lateral side, a second electrode facing the first electrode and an electrolyte interposed between the first and second electrodes, the dye- sensitized solar cell comprising the electrolyte being injected to a space formed by a glass frit sintered body spacing the first and second electrodes from each other at predetermined intervals and tightly sealing the first and second electrodes.

[9] The foregoing and/or other aspects of the present invention are also achieved by providing a manufacturing method of a dye-sensitized solar cell which has a first electrode including a transmissive layer having a porous layer with a dye in a lateral side, a second electrode which faces the first electrode and an electrolyte which is interposed between the first and second electrodes, the manufacturing method comprising applying and firing (sintering) glass frit on a coupling surface of the first and second electrodes and tightly sealing the first and second electrodes together which are spaced from each other at predetermined intervals.

Advantageous Effects

[10] As described above, the dye-sensitized solar cell and the manufacturing method thereof according to the present invention is tightly sealed by a glass frit sintered body to prevent an electrolyte from leaking, secures mechanical strength and prevents an electrolyte from easily volatilizing from a sealing part, is resistant to an external shock or damage and is tightly sealed with strength to extend the life and enhance durability while operating under harsh external environment. Brief Description of the Drawings

[11] The above and/or other aspects of the present invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: [12] FIG. 1 is a sectional view of a dye- sensitized solar cell according to a first exemplary embodiment of the present invention; [13] FIG. 2 is a sectional view of a dye- sensitized solar cell according to a second exemplary embodiment of the present invention; [14] FIG. 3 is a sectional view of a dye- sensitized solar cell according to a third exemplary embodiment of the present invention; [15] FIG. 4 is a sectional view of a dye- sensitized solar cell according to a fourth exemplary embodiment of the present invention; [16] FIG. 5 is a sectional view of a dye- sensitized solar cell according to a fifth exemplary embodiment of the present invention; [17] FIG. 6 is a sectional view of a dye- sensitized solar cell according to a sixth exemplary embodiment of the present invention; [18] FIG. 7 is a sectional view of a dye- sensitized solar cell according to a seventh exemplary embodiment of the present invention; [19] FIG. 8 illustrates a tightly- sealed electrolyte injection hole of the dye-sensitized solar cell according to the exemplary embodiments of the present invention; and [20] FIG. 9 illustrates a processed connection line of the dye- sensitized solar cell according to the exemplary embodiments of the present invention.

Mode for the Invention [21] Hereinafter, exemplary embodiments of the present invention will be described with reference to accompanying drawings, wherein like numerals refer to like elements and repetitive descriptions will be avoided as necessary. [22] A dye-sensitized solar cell according to the present invention includes a first electrode 10 which has a transmissive layer 11 having a porous layer 13 with a dye in a lateral side, a second electrode 20 which faces the first electrode 10 and an electrolyte

30 which is interposed between the first electrode 10 and the second electrode 20. The electrolyte 30 is injected to a space which is formed by a glass frit sintered body 40 to space the first and second electrodes 10 and 20 from each other at predetermined intervals and to seal the first and second electrodes 10 and 20 together. [23] Hereinafter, the dye-sensitized solar cell according to the present invention will be described in more detail with reference to FIGS. 1 to 9. [24] As described above, a dye-sensitized solar cell generally includes the first electrode

10 which has the transmissive layer 11 having the porous layer 13 with a dye in a lateral side, the second electrode 20 which faces the first electrode 10 and the electrolyte 30 which is interposed between the first and second electrodes 10 and 20. According to the present invention, the first and second electrodes 10 and 20 are spaced from each other and a space therebetween is tightly sealed by the glass frit sintered body 40 to inject the electrolyte 30 to the formed sealing space. Thus, the electrolyte 30 is stably maintained for a long time between the first and second electrodes 10 and 20. FIGS. 1 to 9 illustrate the dye-sensitized solar cell according to exemplary embodiments of the present invention. Detailed descriptions will be described hereinafter.

[25] The porous layer 13 includes various known porous layers which are coupled with

(absorb) a dye, e.g., a transition metal oxide porous layer formed by applying and firing (sintering) 10 - 15 nm sized TiO2. The transmissive layer 11 which has the porous layer 13 is not limited to a flat layer. Alternatively, the transmissive layer 11 may include a layer having an uneven surface. The transmissive layer 11 may include various known transmissive layers to be employed in a solar cell. For example, the transmissive layer 11 may include a material such as a glass layer which transmits visible rays or waves in a certain wavelength range beyond visible rays. Preferably, the transmissive layer 11 is conductive to serve as an electrode. As a specific example, the transmissive layer 11 may include known transmissive glass, transmissive resin, PET, ITO or FTO. The transmissive layer 11 may further include a conductive film or a coating layer (ITO, FTO or conductive high molecule) between the porous layer 13 and the transmissive layer 11 to be conductive. The second electrode 20 which faces the first electrode 10 in an opposite side may include a known layer used as a second electrode of a solar cell. The second electrode 20 is not limited to a flat layer. Alternatively, the second electrode 20 may include a layer having an uneven surface. The second electrode 20 may include a material which transmits visible rays or waves in a certain wavelength range beyond visible rays. For example, the second electrode 20 may include known transmissive glass, transmissive resin, PET, ITO or FTO. Preferably, the second electrode 20 may further include a conductive film or a coating layer (ITO, FTO or conductive high molecule) to be conductive. The second electrode 20 may further include a catalyst metal layer such as platinum which is provided in the most external surface of the first electrode 10 to enhance absorption efficiency of sunlight and to activate reaction.

[26] For example, the glass frit sintered body 40 is a solid state which is formed by applying and firing (sintering) glass frit in the circumference of the substrates to seal the substrates together. The glass frit may include various known glass frit. Preferably, the glass frit may include a low melting point glass frit to maintain a process temperature such as a firing process at a lower level. More preferably, the glass frit includes a low melting point glass frit having a melting point of 400 0C and below or a low melting point glass frit having a glass transition temperature of 250 0C and below.

[27] In the dye-sensitized solar cell according to the exemplary embodiment of the present invention, the first electrode 10 includes the transmissive layer 11 having a transmissive material, the porous layer 13 formed on a surface of the transmissive layer 11 and spaced from a circumference 12 of the transmissive layer 11 at predetermined intervals and the dye absorbed to the porous layer 13. The second electrode 20 of the dye-sensitized solar cell includes a support layer 21 and a catalyst metal layer 23 which is formed across a surface of the support layer 21 or spaced from a circumference 22 of the support layer 21 at predetermined intervals. The first and second electrodes 10 and 20 are arranged so that the porous layer 13 and the catalyst metal layer 23 face each other. The glass frit sintered body 40 is formed between the circumference 12 of the transmissive layer 11 not having the porous layer 13 and the catalyst metal layer 23 of the support layer 21 or the circumference 22 of the support layer 21 not having the catalyst metal layer 23 to tightly seal the first and second electrodes 10 and 20 together.

[28] As described above, the transmissive layer 11 may include various known transmissive layers. As shown in FIG. 1, 2 or 7, the transmisstive layer 11 may solely include e.g., a conductive transmssive material such as ITO or FTO. Alternatively, as shown in FIGS. 3 to 6, a conductive film 15, e.g., an ITO or FTO coating layer or a transmissive conductive high molecular layer may be formed on the glass layer (or transmissive high molecule such as PET). The conductive film 15 may be coupled with the glass frit sintered body 40 formed on the conductive film 15 to tightly seal the first and second electrodes 10 and 20 together. As shown in FIG. 5, the conductive film 15 may alternatively be spaced from the circumference of the glass layer like the porous layer 13 so that the glass frit sintered body 40 is directly coupled with the glass layer. In this case, a connection line which is electrically connected to the conductive film 15 is discharged to the outside.

[29] The porous layer 13 which is formed on the transmissive layer 11 may include various known porous layers which absorb a dye to form one surface of the transmissive layer 11. As shown therein, the porous layer 13 is preferably spaced from the circumference 12 of the transmissive layer 11 at predetermined intervals to prevent the electrolyte 30 from leaking through the porous layer 13.

[30] The dye may include various known dyes to be employed in the dye-sensitized solar cell. The method of applying the dye to the porous layer 13 to be absorbed thereto is known in the art.

[31] As shown in FIG. 7, the first electrode 10 may further include a bulk layer 16 as an additional transition metal oxide on the porous layer 13. The bulk layer 16 may be formed by applying and firing 400 nm - 500 nm TiO2 to thereby enhance absorption efficiency of sunlight.

[32] The support layer 21 of the second electrode 20 may include various known support layers. Preferably, the transmissive layer 11 may be employed. As shown in FIG. 1, 2 or 7, the support layer 21 may solely include e.g., a conductive transmissive material such as ITO or FTO. Alternatively, as shown in FIGS. 3 to 6, a conductive film 26, e.g., an ITO or FTO coating layer or a transmissive conductive high molecular layer may be formed on the glass layer (or transmissive high molecule such as PET). The conductive film 26 may be coupled with the glass frit sintered body 40 formed on the conductive film 26 to tightly seal the first and second electrodes 10 and 20 together. As shown in FIG. 5, the conductive film 26 may alternatively be spaced from the circumference of the glass layer like the porous layer 13 of the first electrode 10 so that the glass frit sintered body 40 is directly coupled with the glass layer or ITO/FTO layer. In this case, a connection line which is electrically connected to the conductive film 26 is discharged to the outside.

[33] The second electrode 20 may further include the catalyst metal layer 23 added to the support layer 21. As shown therein, the catalyst metal layer 23 may be i) formed (applied or coated) across a surface of the support layer 21 or ii) spaced from the circumference 22 of the support layer 21 at predetermined intervals. That is, the catalyst metal layer 23 may be formed across the surface of the support layer 21 as shown in FIGS. 1 and 3 or may be spaced from the circumference 22 of the support layer 21 at predetermined intervals as shown in FIGS. 2, 4 to 7.

[34] Thus, the glass frit sintered body 40 may be coupled with the catalyst metal layer 23

(refer to FIGS. 1 and 3) of the second electrode 20 or selectively coupled with the glass layer (refer to FIG. 5), the ITO/FTO layer (refer to FIGS. 2, 6 and 7) or the conductive films 15 and 25 (refer to FIG. 4).

[35] That is, the porous layer 13 of the first electrode 10 faces the catalyst metal layer 23 of the second electrode 20. The glass frit sintered body 40 is formed between the circumference 12 of the transmissive layer 11 not having the porous layer 13 and i) the catalyst metal layer 23 of the support layer 21 or ii) the circumference 22 of the support layer 21 not having the catalyst metal layer 23 to tightly seal the first and second electrodes 10 and 20 together.

[36] The dye-sensitized solar cell according to the present invention further includes an electrolyte injection hole to inject the electrolyte 30 therethrough. Preferably, the second electrode 20 further includes the injection hole 25 to inject the electrolyte 30 therethrough. The electrolyte injection hole 25 may be tightly sealed by a glass frit sintered body 50. FIG. 8 illustrates the electrolyte injection hole 25 according to the exemplary embodiment of the present invention. As the electrolyte injection hole 25 is sealed by the glass frit sintered body 50, the electrolyte 30 is prevented from leaking therethrough to thereby ensure durability of the solar cell.

[37] The first electrode 10 or the second electrode 20 of the dye-sensitized solar cell according to the present invention further includes a connection line 60 which is discharged to the outside of the unit cell. Preferably, the connection line 60 is inserted to a glass frit sintered body 70 and attached to a lateral side of the solar cell. Here, the unit cell of the dye-sensitized solar cell refers to a single unit as shown in FIGS. 1 to 9. Each unit cell includes the connection line 60 to be connected with one another or to supply electricity to an external device. If the connection line 60 is exposed to the outside, short-circuit or electric discharge may occur. Thus, a glass frit as an insulator is applied to the connection line 60 and then the connection line 60 is attached to the lateral side of the dye-sensitized solar cell to prevent damage by an external shock. If the connection line 60 is discharged from the lateral side of the dye-sensitized solar cell, the glass frit is applied to the connection line 60 and then fired. The connection line 60 is inserted to the glass frit sintered body 70.

[38] The present invention provides a manufacturing method of the dye-sensitized solar cell. The manufacturing method of the dye-sensitized solar cell which includes the first electrode 10 having the transmissive layer 11 including the porous layer 13 with the dye in a lateral side, the second electrode 20 facing the first electrode 10 and the electrolyte 30 interposed between the first and second electrodes 10 and 20 comprises applying and firing a glass frit on a coupling surface between the first and second electrodes 10 and 20 and sealing the first and second electrodes 10 and 20 together which are spaced from each other at predetermined intervals.

[39] That is, the manufacturing method of the various types of dye-sensitized solar cells comprises applying and firing the glass frit between the first and second electrodes 10 and 20 to tightly seal the first and second electrodes 10 and 20 by the glass frit sintered body 40.

[40] The glass frit may include the foregoing glass frit. The method of applying the glass frit may include various known methods. Preferably, a paste type glass frit may be applied to the circumferences 12 and 22 of the first and second electrodes 10 and 20. The applied glass frit may be fired by a known firing method or fired by heating only the glass frit-applied part with a laser. The glass frit is locally heated to thereby minimize thermal shock to other elements.

[41] The manufacturing method of the dye-sensitized solar cell according to the present invention may include an operation of providing a transmissive layer having a first electrode transmissive material, an operation of forming a porous layer spaced from the circumference of the transmissive layer at predetermined intervals, an operation of applying a dye to the porous layer to be absorbed thereto, an operation of providing a support layer of the second electrode, an operation of forming a catalyst metal layer across a surface of the support layer or spaced from the circumference of the support layer at predetermined intervals, an operation of applying the glass frit between the circumference of the transmissive layer not having the porous layer and the catalyst metal layer of the support layer or the circumference of the support layer not having the catalyst metal layer, an operation of coupling the first and second electrodes so that the porous layer and the catalyst metal layer face each other and an operation of firing the applied glass frit to tightly seal the first and second electrodes together.

[42] The transmissive layer may include the foregoing known transmissive layers. More specifically, the transmissive layer may include an insulator such as ITO, FTO or a glass layer added with a conductive film. The porous layer may include the foregoing known porous layers. Preferably, the porous layer is formed by applying and firing 10 nm - 15 nm TiO2. The method of applying the dye to the porous layer is known in the art. Preferably, a substrate having the porous layer is soaked into a dye solution so that the porous layer absorbs the dye. The process of applying the dye may be performed after a bulk layer is formed as shown in FIG. 7. Alternatively, the process of applying the dye may be performed before the first and second electrodes are coupled to each other to fill in the space therebetween with an electrolyte (by injecting a dye solution to the electrolyte injection hole which will be described later). The order may differ as long as the dye is absorbed to the porous layer. As described above, the bulk layer may be formed on the porous layer.

[43] Then, the support layer of the second electrode is provided and the catalyst metal layer is formed by a coating method, e.g., by plating or sputtering.

[44] Preferably, the porous layer is spaced from the circumference of the transmissive layer at predetermined intervals. The catalyst metal layer may be spaced from the circumference of the support layer at predetermined intervals, but not limited thereto. Alternatively, the catalyst metal layer may be formed across the surface of the support layer.

[45] The glass frit is applied to the first and second electrodes with various methods as shown in FIGS. 1 to 9 and then fired (including fired by laser heating) to tightly seal the first and second electrodes together.

[46] The manufacturing method of the dye-sensitized solar cell may further include an operation of forming an injection hole on the second electrode to inject the electrolyte therethrough, an operation of injecting the electrolyte through the injection hole and an operation of applying and firing the glass frit to the injection hole to seal the injection hole. The operation of forming the electrolyte injection hole may be performed only before the operation of injecting the electrolyte. Thus, the operation of forming the electrolyte injection hole may be performed before or after the operation of the providing the support layer, after the operation of forming the catalyst metal layer or after the operation of coupling the first and second electrodes.

[47] After the electrolyte which is required to manufacture the dye-sensitized solar cell is injected through the electrolyte injection hole, the glass frit is applied to the injection hole and then fired to be sealed as shown in FIG. 8.

[48] The manufacturing method of the dye-sensitized solar cell may further include an operation of coupling a connection line discharged from the first electrode or the second electrode to the outside of the unit cell, an operation of selectively discharging the connection line to the lateral side of the solar cell and an operation of applying and firing the glass frit to the connection line and the lateral side of the solar cell to attach the connection line to the lateral side of the solar cell. The operation of coupling the connection line may be performed in a proper step of the manufacturing method of the dye-sensitized solar cell or performed through a known additional method to discharge the connection line from the first and second electrodes and to move electrons therefrom. Generally, a solar cell requires a connection line, and the discharging of the connection line is known in the art.

[49] The operation of insulating the discharged connection line and attaching the connection line to the lateral side of the solar cell is performed after the solar cell is completely manufactured, but not limited thereto. Alternatively, the operation of insulating and attaching the connection line may be performed anytime as long as the first and second electrodes are sealed to each other and the lateral side of the solar cell is not changed. As described above, the glass frit may be fired (sintered) by a general firing (sintering) process or only the glass frit-applied part may be locally sintered by applying a laser on the part.

[50] Although a few exemplary embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these exemplary embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents. Industrial Applicability

[51] As described above, the dye-sensitized solar cell and the manufacturing method thereof according to the present invention is tightly sealed by a glass frit sintered body to prevent an electrolyte from leaking, secures mechanical strength and prevents an electrolyte from easily volatilizing from a sealing part, is resistant to an external shock or damage and is tightly sealed with strength to extend the life and enhance durability while operating under harsh external environment.

Claims

[1] A dye-sensitized solar cell which has a first electrode including a transmissive layer having a porous layer with a dye in a lateral side, a second electrode facing the first electrode and an electrolyte interposed between the first and second electrodes, the dye- sensitized solar cell, comprising: the electrolyte being injected to a space formed by a glass frit sintered body spacing the first and second electrodes from each other at predetermined intervals and tightly sealing the first and second electrodes together.

[2] The dye-sensitized solar cell according to claim 1, wherein the first electrode comprises a transmissive layer having a transmissive material, a porous layer being spaced from a circumference of a surface of the transmissive layer at predetermined intervals and a dye absorbed by the porous layer, the second electrode comprises a support layer and a catalyst metal layer formed across the support layer or on a circumference of a surface of the support layer at predetermined intervals, the first and second electrodes are arranged so that the porous layer and the catalyst metal layer face each other, and the glass frit sintered body is formed between a circumference of the transmissive layer not having the porous layer and the catalyst metal layer of the support layer or a circumference of the support layer not having the catalyst metal layer and tightly seals the first and second electrodes together.

[3] The dye-sensitized solar cell according to claim 1, wherein the second electrode further comprises an injection hole to inject an electrolyte therethrough, and the electrolyte injection hole is tightly sealed by a glass frit sintered body.

[4] The dye-sensitized solar cell according to claim 1, wherein the first electrode or the second electrode further comprises a connection line which is discharged to the outside of a unit sell, and the connection line is selectively inserted to a glass frit sintered body and attached to a lateral side of the solar cell.

[5] A manufacturing method of a dye-sensitized solar cell which has a first electrode including a transmissive layer having a porous layer with a dye in a lateral side, a second electrode facing the first electrode and an electrolyte being interposed between the first and second electrodes, the manufacturing method comprising: applying and firing a glass frit to a coupling surface of the first and second electrodes and tightly sealing the first and second electrodes together which are spaced from each other at predetermined intervals.

[6] The manufacturing method according to claim 5, further comprising: providing a transmissive layer which comprises a first electrode transmissive material; forming a porous layer which is spaced from a circumference of a surface of the transmissive layer at predetermined intervals; applying a dye to the porous layer to be absorbed; providing a second electrode support layer; forming a catalyst metal layer which is provided across a surface of the support layer or is spaced from a circumference of the surface of the support layer at predetermined intervals; applying a glass frit between a circumference of the transmissive layer not having the porous layer and a catalyst metal layer of the support layer or a circumference of the support layer not having the catalyst metal layer; and coupling the first and second electrode so that the porous layer and the catalyst metal layer face each other, firing the applied glass frit and tightly sealing the first and second electrodes together.

[7] The manufacturing method according to claim 5, further comprising: forming an injection hole on the second electrode to inject an electrolyte therethrough; injecting an electrolyte to the injection hole; and applying and firing a glass frit on the injection hole to tightly seal the injection hole.

[8] The manufacturing method according to claim 5, further comprising: coupling a connection line which is discharged from the first electrode or the second electrode to the outside of a unit cell; and selectively discharging the connection line to a lateral side of a solar cell, applying and firing a glass frit around the connection line and the lateral side of the solar cell and attaching the connection line to the lateral side of the solar cell.

[9] The manufacturing method according to one of claims 5 to 8, wherein the firing the glass frit comprises heating only the glass frit-applied part with a laser.

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