Patent Publication Number: US-2012037218-A1

Title: Electrode for photoelectric conversion device, method of preparing the same and 
photoelectric conversion device comprising the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2010-0077307, filed on Aug. 11, 2010, in the Korean Intellectual Property Office, the entire content of which is incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     Aspects of embodiments of the present invention relate to an electrode for a photoelectric conversion device, a method of preparing the same and a photoelectric conversion device including the same. 
     2. Description of the Related Art 
     Solar cells are desired sources of energy because solar energy is virtually unlimited and eco-friendly unlike other comparable energy sources. Solar cells are classified into silicon solar cells, dye solar cells, etc. 
     Silicon solar cells are difficult to be put to practical use because their fabrication costs are relatively high. Further, it is very difficult to improve the efficiency of the silicon solar cells. 
     On the other hand, dye solar cells are photoelectric chemical solar cells using a dye molecule and a transition metal oxide as their main material components. Here, the dye molecule generates electron-hole pairs by absorbing visible light, and the transition metal oxide transfers the generated electrons. Since the dye solar cells have remarkably lower fabrication costs than existing silicon-based solar cells, they may replace conventional amorphous silicon solar cells. 
     A method of printing silver paste and then drying and sintering the printed silver paste is frequently used as a method of forming an electrode for a dye solar cell. In the silver paste, silver powder, binder, organic solvent and the like are mixed together. 
     However, silver (Ag) is a high-priced precious metal. When the silver paste is kept for a long period of time, the phase separation of the silver paste occurs, and therefore, has influence on properties of a film formed with the silver paste. Also, since a difference in viscosity and rheology property occurs due to the continuous volatilization of the organic solvent in the printing process, the properties of the film are not constant. 
     In addition, since the method includes printing, drying and sintering processes, process time is increased, and there are other additional process costs, such as cost for replacing a silk screen mask and a squeegee, cost for performing a grinding process, and cost for maintaining drying and sintering furnaces, which are additionally consumed in the printing and sintering processes. 
     SUMMARY 
     Aspects of embodiments of the present invention are directed toward an electrode for a photoelectric conversion device, a method of preparing the same and a photoelectric conversion device including the same, which can enhance price competitiveness and simplify preparing processes by replacing a conventional electrode material. 
     According to an embodiment of the present invention, there is provided an electrode for a photoelectric conversion device, the electrode including: a transparent conductive layer formed on a substrate; a metal electrode layer disposed on the transparent conductive layer to have a pattern; and an intermediate electrode layer interposed between the transparent conductive layer and the metal electrode layer to join the transparent conductive layer and the metal electrode layer. 
     The intermediate electrode layer may include a material selected from the group consisting of Ti, Cr, Ni, Nb, Mo, Sn, Ta, W, Pt, Au, sus, ITO, FTO, ZnO, SnO(II), SnO 2 (IV) and combinations thereof. 
     The intermediate electrode layer may have a thickness at 0.01 μm or 10 μm or between 0.01 μm and 10 μm. 
     The intermediate electrode layer may have a pattern matching the pattern of the metal electrode layer. 
     The metal electrode layer may include a material selected from the group consisting of Al, Ni, Cu, Zn, Mo, Ag, Pt, Au and combinations thereof. 
     The metal electrode layer may have a thickness at 0.01 μm or 10 μm or between 0.1 μm and 100 μm. 
     According to an embodiment of the present invention, there is provided a method of preparing an electrode for a photoelectric conversion device, the method including: providing a substrate having a transparent conductive layer formed thereon; forming an intermediate electrode layer having to have a pattern on the transparent conductive layer; and forming a metal electrode layer on the intermediate electrode layer so that the metal electrode layer is joined with the intermediate electrode layer. 
     The forming of the intermediate electrode layer may include disposing a first mask having openings respectively matching portions of the transparent conductive layer; and depositing an intermediate electrode forming material on the transparent conductive layer through the openings. 
     The intermediate electrode forming material may include a material selected from the group consisting of Ti, Cr, Ni, Nb, Mo, Sn, Ta, W, Pt, Au, sus, ITO, FTO, ZnO, SnO(II), SnO 2 (IV) and combinations thereof. 
     The intermediate electrode forming material may be deposited to have a thickness at 0.01 μm or 10 μm or between 0.01 μm and 10 μm. 
     The forming of the intermediate electrode layer and the metal electrode layer may include depositing an intermediate electrode forming material on the transparent conductive layer, thereby forming a preliminary intermediate electrode layer; depositing a metal electrode forming material on the intermediate electrode forming material, thereby forming a preliminary metal electrode layer; and etching the preliminary intermediate electrode layer and the preliminary metal electrode layer. 
     According to an embodiment of the present invention, there is provided a photoelectric conversion device including: a first electrode formed on a first substrate; a photoelectrode layer formed on at least one surface of the first electrode, the photoelectrode layer including a photo-sensitizing dye; a second electrode formed on a second substrate and facing the first electrode; a counter-electrode layer formed on at least one surface of the second electrode, the counter-electrode layer including a conductive catalyst; and a sealing member joining the first and second electrodes and an electrolyte solution injected into a space between the first and second electrodes and sealed in the space between the first and second electrode by the sealing member, wherein at least one of the first and second electrodes includes a transparent conductive layer formed on a corresponding one of the first and second substrates, a metal electrode layer disposed on the transparent conductive layer to have a pattern, and an intermediate electrode layer interposed between the transparent conductive layer and the metal electrode layer to join the transparent conductive layer and the metal electrode layer. 
     As described above, according to the embodiments of the present invention, the price competitiveness of the photoelectric conversion device can be enhanced by replacing a conventional electrode material. 
     Also, the adhesion between the metal electrode layer and the transparent conductive layer is increased due to the intermediate electrode layer interposed between the transparent conductive layer and the metal electrode layer, so that it is possible to prevent (or protect from) a phenomenon in which the electrolyte solution is penetrated into the interface between the transparent conductive layer and the metal electrode layer, and therefore, the metal electrode layer gets loose. Accordingly, it is possible to increase the photoelectric conversion efficiency of the photoelectric conversion device and to enhance the reliability of the photoelectric conversion device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, together with the specification, illustrate exemplary embodiments of the present invention, and, together with the description, serve to explain the principles of the present invention. 
         FIG. 1  is a sectional view schematically showing the entire configuration of a photoelectric conversion device according to an embodiment of the present invention. 
         FIG. 2  is a view schematically showing the state in which a dye is connected to an inorganic metal oxide semiconductor. 
         FIG. 3  is a sectional view schematically showing the structure of an electrode for the photoelectric conversion device according to the embodiment of the present invention. 
         FIG. 4  is a scanning electron microscope (SEM) image showing the structure of the electrode for the photoelectric conversion device according to the embodiment of the present invention. 
         FIGS. 5A to 5E  are sectional views schematically showing processes of preparing an electrode for the photoelectric conversion device according to a first embodiment of the present invention. 
         FIGS. 6A to 6D  are sectional views schematically showing processes of preparing an electrode for the photoelectric conversion device according to a second embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, only certain exemplary embodiments of the present invention have been shown and described, simply by way of illustration. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive. In addition, when an element is referred to as being “on” another element, it can be directly on the another element or be indirectly on the another element with one or more intervening elements interposed therebetween. Also, when an element is referred to as being “connected to” another element, it can be directly connected to the another element or be indirectly connected to the another element with one or more intervening elements interposed therebetween. Hereinafter, like reference numerals refer to like elements. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this disclosure. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be understood that the terms “comprises” and/or “comprising”, or “includes” and/or “including” when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and/or groups thereof. 
     Hereinafter, an electrode for a photoelectric conversion device and a photoelectric conversion device including the same according to an embodiment of the present invention will be described in more detail with reference to  FIGS. 1 to 3 . 
       FIG. 1  is a sectional view schematically showing the entire configuration of a photoelectric conversion device according to an embodiment of the present invention.  FIG. 2  is a view schematically showing the state in which a dye is connected to an inorganic metal oxide semiconductor.  FIG. 3  is a sectional view schematically showing the structure of an electrode for the photoelectric conversion device according to the embodiment of the present invention. 
     Referring to  FIGS. 1 and 2 , a photoelectric conversion device  1  according to an embodiment of the present invention includes a first substrate  11 , a second substrate  11 ′, a first electrode  10 , a second electrode  10 ′, a photoelectrode layer  3 , a counter-electrode layer  7 , an electrolyte solution  5 , a sealing member  9  and extracting wires W. 
     The first and second substrates  11  and  11 ′ are disposed to face (or to oppose) each other with a set or predetermined interval therebetween. The material of the first and second substrates  11  and  11 ′ can be any suitable transparent material having a low light absorption with respect to a spectrum or range from a visible region to a near infrared region of light (e.g., sunlight or the like) incident on the photoelectric conversion device  1  from the exterior of the photoelectric conversion device  1 . 
     In one embodiment, the material of the first and second substrates  11  and  11 ′ include a glass material such as quartz, general glass, crown glass (borosilicate glass or BK7) or lead glass, a resin material such as polyethylene terephthalate, polyethylene naphthalate, polyimide, polyester, polyethylene, polycarbonate, polyvinylbutyrate, polypropylene, tetraacetylcellulose, syndiotactic polystyrene, polyphenylenesulfide, polyarylate, polysulfone, polyestersulfone, polyetherimide, annular polyolefin, phenoxy bromide or vinyl chloride, or the like. 
     In the first and second substrates  11  and  11 ′, a transparent conductive layer  13  formed into a film, for example, using a transparent conductive oxide (TCO) is formed on a surface of at least the first substrate  11  onto which external light is incident. The TCO can be any suitable conductive material having a low light absorption with respect to a spectrum or range from a visible region to a near infrared region of light incident from the exterior of the photoelectric conversion device  1 . For example, the TCO may be a metal oxide having excellent conductivity, such as indium tin oxide (ITO), tin oxide (SnO 2 ), fluorine-doped tin oxide (FTO), antimony-doped tin oxide (ATO) or zinc oxide (ZnO 2 ). 
     In order to enhance photoelectric conversion efficiency, the surface resistance of the first and second electrodes  10  and  10 ′ should be as low as possible. 
     However, in the first and second substrates  11  and  11 ′, the second electrode  10 ′ formed on a surface of the second substrate  11 ′ opposite to (or facing away from) the first substrate  11  is not essential. In a case where the second electrode  10 ′ is formed on the surface of the second substrate  11 ′, it is not necessarily transparent. That is, the second electrode  10 ′ does not necessarily have a low absorption with respect to a spectrum or range from a visible region to a near infrared region of light incident from the exterior of the photoelectric conversion device  1 . 
     Also, detailed description of the first or second electrode  10  or  10 ′ according to this embodiment will be described later in more detail. 
     In the photoelectric conversion device  1 , the photoelectrode layer  3  is used as an inorganic metal oxide semiconductor layer having a photoelectric conversion function. The photoelectrode layer  3  is formed as a porous layer. 
     More specifically, as shown in  FIGS. 1 and 2 , the photoelectrode layer  3  is formed by stacking a plurality of metal oxide corpuscles  31  such as TiO 2  on the surface of the first electrode  10 . The metal oxide corpuscles  31  stacked as described above constitute a porous body, i.e., a nano-porous layer containing nano-meter pores therein. 
     As described above, the photoelectric layer  3  is formed into a porous body containing a plurality of micro-pores, so that it is possible to increase the surface area of the photoelectrode layer  3  and to connect a large amount of sensitizing dye  33  to the surface of the metal oxide corpuscle  31 . Accordingly, the photoelectric conversion device  1  can have high photoelectric conversion efficiency. 
     In the photoelectrode layer  3 , the sensitizing dye  33  is connected to the surface of the metal oxide corpuscle  31  with a linking group  35  interposed therebetween, thereby obtaining the photoelectrode layer in which inorganic metal oxide semiconductors are sensitized. 
     Also, the term “linking” refers to that the inorganic metal oxide semiconductor and the sensitizing dye are chemically or physically bonded to each other (e.g., bonding by absorption or the like). Therefore, the term “linking group” includes not only a chemical functional group but also an anchoring or adsorbing group. 
     Although  FIG. 2  shows a state in which only one sensitizing dye  33  is connected on the surface of the metal oxide corpuscle  31 , it is only a simple schematic view. In order to increase electrical power of the photoelectric conversion device  1 , it is preferable that the number of sensitizing dyes  33  connected to the surface of the metal oxide corpuscle  31  is as many as possible, and a large number of sensitizing dyes  33  are coated on the surface of the metal oxide corpuscle  31  as wide as possible. 
     However, in a case where the number of the coated sensitizing dyes is increased, excited electrons may be recombined by interaction between approaching sensitizing dyes  33 , and therefore, these electrons may not be extracted as electric energy. Hence, a co-adsorption substance such as deoxycholic acid may be used so that the sensitizing dyes  33  can be coated while maintaining an appropriate distance therebetween. 
     The photoelectrode layer  3  may be formed by stacking the metal oxide corpuscles  31  having a size of about 20 to 100 nm as a number-average particle size of a primary particle into a multi-layered structure. The thickness of the photoelectrode layer  3  may be a few μm (preferably, less than 10 μm). 
     If the thickness of the photoelectrode layer  3  is thinner than a few μm, light that transmits the photoelectrode layer  3  is increased, and the light excitation of the sensitizing dyes  33  is insufficient. Therefore, effective photoelectric conversion efficiency may not be obtained. 
     Also, if the thickness of the photoelectrode layer  3  is thicker than a few μm, the distance between the surface of the photoelectrode layer  3  (the surface that comes in contact with the electrolyte solution  5 ) and the electrical conducting surface (the interface between the photoelectrode layer  3  and the first electrode  10 ) is lengthened. Therefore, since it is difficult that excited electrons are effectively transferred to the electrical conducting surface, satisfactory photoelectric conversion efficiency may not be obtained. 
     Next, the metal oxide corpuscle  31  and the sensitizing dye  33 , available for the photoelectrode layer  3  according to an embodiment of the present invention, will be described in more detail. 
     Generally, the inorganic metal oxide semiconductor has a photoelectric conversion function for light in a partial wavelength region. However, the sensitizing dye  33  is connected to the surface of the metal oxide corpuscle  31 , so that photoelectric conversion is possible with respect to light in a spectrum or range from a visible region to a near infrared region. 
     A compound available for the metal oxide corpuscle  31  is not particularly limited as long as it is a compound that connects the sensitizing dye  33  and has a sensitized photoelectric conversion function. For example, the compound may include titanium oxide, tin oxide, tungsten oxide, zinc oxide, indium oxide, niobium oxide, iron oxide, nickel oxide, cobalt oxide, strontium oxide, tantalum oxide, antimony oxide, lanthanide oxide, yttrium oxide, vanadium oxide, or the like. 
     Here, since the surface of the metal oxide corpuscle  31  is sensitized by the sensitizing dye  33 , the conduction band of the inorganic metal oxide may exist at a position at which it easily receives electrons from the optical excitation trap of the sensitizing dye  33 . 
     In this viewpoint, the compound used as the metal oxide corpuscle  31  may include titanium oxide, tin oxide, zinc oxide, niobium oxide or the like. In the viewpoint of price, environment or the like, the compound used as the metal oxide corpuscle  31  may include titanium oxide. 
     The sensitizing dye  33  is not particularly limited as long as it is a dye having a photoelectric conversion function with respect to light in a set spectrum or range (e.g., in a spectrum or range from a visible light region to a near infrared light region) having no photoelectric conversion function. For example, the sensitizing dye  33  may include an azo-based dye, a quinacridone-based dye, a diketopyrrolopyrrole-based dye, a squarylium-based dye, a cyanine-based dye, a merocyanine-based dye, a triphenylmethane-based dye, a xanthene-based dye, a porphyrin-based dye, a chlorophyll-based dye, a ruthenium complex-based dye, an indigo-based dye, a perylene-based dye, a dioxadine-based dye, an anthraquinone-based dye, a phthalocyanine-based dye, a naphthalocyanine-based dye, a derivative thereof, or the like. 
     The sensitizing dye  33  may include a functional group connectable to the surface of the metal oxide corpuscle  31  as the linking group so that excitation electrons of the optically excited dye can be rapidly transferred to the conduction band of the inorganic metal oxide. 
     The functional group is not particularly limited as long as it is a substituting group having a function that connects the sensitizing dye  33  to the surface of the metal oxide corpuscle  31  and rapidly transfers the excitation electrons of the dye to the conduction band of the inorganic metal oxide. For example, the functional group may include a carboxyl group, a hydroxyl group, a hydroxamic acid group, a sulfinyl group, a phosphonic acid group, a phosphinic acid group, or the like. 
     The counter-electrode layer  7  serves as a positive electrode of the photoelectric conversion device  1 . The counter-electrode layer  7  is formed as a film on the surface of the second substrate  11 ′ with the second electrode  10 ′ formed thereon, opposing or facing the first substrate  11  with the first electrode  10  formed thereon. 
     That is, the counter-electrode layer  7  is disposed on the surface of the second electrode  10 ′ to be opposite to the photoelectrode layer  3  in a region surrounded by the first electrode  10 , the second electrode  10 ′ and the sealing member  9 . 
     A metal catalyst layer having conductivity is disposed on a surface of the counter-electrode layer  7  (a side of the counter-electrode layer  7 , opposite to the photoelectrode layer  3 ). 
     For example, the conductive material available for the counter-electrode layer  7  may include metal (platinum, gold, silver, copper, aluminum, rhodium, indium or the like), metal oxide (indium tin oxide (ITO)), tin oxide (including tin oxide doped with fluorine or the like), zinc oxide, conductive carbon material, conductive organic material, or the like. 
     The thickness of the counter-electrode layer  7  is not particularly limited. For example, the thickness of the counter-electrode layer  7  may be at 5 nm or 10 μm or between 5 nm and 10 μm. 
     Also, the extracting wires W are respectively connected to the counter-electrode layer  7  and the first electrode  10  of the side at which the photoelectrode layer  3  is formed. The extracting wire W from the first electrode  10  and the extracting wire W from the counter-electrode layer  7  are connected to each other at the exterior of the photoelectric conversion-device  1 . 
     The first electrode  10  and the counter-electrode layer  7  may be isolated from each other so as to be sealed by the sealing member  9  while being spaced apart from each other. 
     The sealing member  9  is formed along outer circumferential portions of the first electrode  10  and the counter-electrode layer  7 . The sealing member  9  may function to seal a space between the first electrode  10  and the counter-electrode layer  7 . 
     A resin having high sealing performance and corrosion resistance may be used as the sealing member  9 . For example, the resin may include thermoplastic resin, photocurable resin, ionomer resin, glass frit, or the like, which are formed in a film shape. 
     Also, the electrolyte solution  5  is injected into the space between the first electrode  10  and the counter-electrode layer  7  and then sealed by the sealing member  9 . 
     For example, the electrolyte solution  5  includes an electrolyte, a medium and an additive. 
     Here; the electrolyte may include a redox electrolyte such as an I 3   − /I −  or Br 3   − /Br −  series, or the like. For example, the electrolyte may include a mixture of I2 and iodide (LiI, NaI, KI, CsI, MgI 2 , CuI, tetraalkylammonium iodide, pyridinium iodide, imidazolium iodide and the like), a mixture of Br 2  and bromide (LiBr and the like), an organic molten salt compound, and the like. However, the substance used as the electrolyte is not limited thereto. 
     The aforementioned iodide, bromide or the like may be used singly or in combinations thereof. 
     Particularly, the electrolyte may include a mixture of I 2  and iodide (e.g., I 2  and LH), and an electrolyte mixed with pyridinium iodide, imidazolium iodide or the like. However, the electrolyte is not limited thereto. 
     In the electrolyte solution  5 , the concentration of the I 2  may be at 0.01 or 0.5 M or between 0.01 and 0.5 M, and any one or both of the iodide and bromide (in the combinations thereof) may be at 0.1 or 15 M or between 0.1 and 15 M. 
     The medium used in the electrolyte solution  5  may be a compound capable of realizing excellent ion conductivity. The medium may include a liquid-phase medium, a solid-phase medium or an ionic liquid. 
     Various suitable kinds of additives may be added into the electrolyte solution  5  so as to enhance the durability of the photoelectric conversion device  1  or electric power. 
     The thickness of the layer put and sealed in the electrolyte solution  5  is not particularly limited. However, the layer may be formed to have a thickness in which the counter-electrode layer  7  does not come in direct contact with the photoelectrode layer  3  having the adsorbed dye. Specifically, the thickness of the layer may be at 0.01 μm or 10 μm or between 0.1 and 100 μm. 
     In the photoelectrode layer  3  including the metal oxide corpuscle  31  and the sensitizing dye  33  connected to the surface of the metal oxide corpuscle  31  with the linking group  35  interposed therebetween, light comes in contact with the sensitizing dye  33  connected to the surface of the metal oxide corpuscle  31  as illustrated in  FIG. 2 . Then, the sensitizing dye  33  is in an excitation state and emits optically excited electrons. The emitted excitation electrons are transferred to the conduction band of the metal oxide corpuscle  31  through the linking group  35 . 
     The excitation electrons that approach the metal oxide corpuscle  31  are transferred to another metal oxide corpuscle  31  to approach the first electrode  10 , and flow out to the exterior of the photoelectric conversion device  1  through the extracting wire W. 
     Also, the sensitizing dye  33  that is in a state in which electrons are deficient due to the emitted excitation electrons receives electrons supplied from the counter-electrode layer  7  through the electrolyte such as I 3   − /I −  in the electrolyte solution  5 , and thus, returns to an electrically neutral state. 
     Hereinafter, the configuration of an electrode for a photoelectric conversion device according to embodiments of the present invention will be described with reference to  FIGS. 1 and 3  to  6 D. 
       FIG. 1  is a sectional view schematically showing the entire configuration of a photoelectric conversion device according to an embodiment of the present invention.  FIG. 3  is a sectional view schematically showing the structure of an electrode for the photoelectric conversion device according to the embodiment of the present invention.  FIG. 4  is a scanning electron microscope (SEM) image showing the structure of the electrode for the photoelectric conversion device according to the embodiment of the present invention.  FIGS. 5A to 5E  are sectional views schematically showing processes of preparing an electrode for the photoelectric conversion device according to a first embodiment of the present invention.  FIGS. 6A to 6D  are sectional views schematically showing processes of preparing an electrode for the photoelectric conversion device according to a second embodiment of the present invention. For convenience purposes, the following description discloses in detail a first electrode  10  and a first substrate  11 . However, it should be apparent that in the following description, the first electrode (the electrode)  10  ( 10 ′) can refer to the first electrode  10  or the second electrode  10 ′ as shown in  FIG. 1 , and the first substrate (the substrate)  11  ( 11 ′) can refer to the first substrate  11  or the second substrate  11 &#39;s as shown in  FIG. 1 . 
     Referring to  FIG. 4 , a first electrode  10  (or electrode  10 ′) for the photoelectric conversion device  1  according to the embodiment of the present invention includes a transparent conductive layer  13  formed on a first substrate  11  (or substrate  11 ′); a metal electrode layer  17  formed on the transparent conductive layer  13  to have a set or predetermined pattern; and an intermediate layer  15  interposed between the transparent conductive layer  13  and the metal electrode layer  17  to join the transparent conductive layer  13  and the metal electrode layer  17 . 
     Here, the intermediate electrode layer  15  is interposed between the transparent conductive layer  13  and the metal electrode layer  17  as described above so that the transparent conductive layer  13  and the metal electrode layer  17  are well joined together. 
     In order to enhance adhesion, the intermediate electrode layer  15  may include at least one selected from the group consisting of Ti, Cr, Ni, Nb, Mo, Sn, Ta, W Pt, Au, sus, ITO, FTO, ZnO, SnO(II), and SnO 2 (IV) and/or an alloy including at least two selected from the group consisting of Ti, Cr, Ni, Nb, Mo, Sn, Ta, W, Pt, Au, sus, ITO, FTO, ZnO, SnO(II), and SnO 2 (IV). The intermediate electrode layer  15  may be formed to have a thickness at 0.01 μm or 10 μm or between 0.01 μm and 10 μm. 
     Also, the intermediate electrode layer  15  may have a pattern with the same (or identical) shape as (or matching) the pattern of the metal electrode layer  17 . In view of the enhancement of the adhesion between the transparent conductive layer  13  and the metal electrode layer  17 , the intermediate electrode  15  may be formed slightly larger than the pattern of the metal electrode layer  17 . However, if the intermediate electrode layer  15  is formed larger than that shown in  FIG. 3 , light incident onto the photoelectric conversion device  1  is screened (or blocked) by the increased area, and therefore, the photoelectric conversion efficiency of the photoelectric conversion device  1  may be decreased. 
     The metal electrode layer  17  is formed on the intermediate electrode layer  15  formed on the transparent conductive layer  13  to increase the adhesion between the transparent conductive layer  13  and the metal electrode layer  17 . The metal electrode layer  17  has a pattern with the same (or identical) shape as (or matching) the pattern of the intermediate electrode layer  15 . As described above, the adhesion between the metal electrode layer  17  and the transparent conductive layer  13  is increased due to the intermediate electrode layer  15  interposed between the transparent conductive layer  13  and the metal electrode layer  17 , so that it is possible to prevent (or protect from) a phenomenon that the electrolyte solution  5  (see  FIG. 1 ) is penetrated into the interface between the transparent conductive layer  13  and the metal electrode layer  17 , and therefore, the metal electrode layer  17  gets loose. Accordingly, it is possible to increase the photoelectric conversion efficiency of the photoelectric conversion device  1  and to enhance the reliability of the photoelectric conversion device  1 . Referring to  FIG. 4 , it can be seen that the metal electrode layer  17  is formed on the intermediate electrode layer  15  that increases the adhesion to having uniform thickness and shape without looseness. 
     The metal electrode layer  17  may include at least one selected from the group consisting of Al, Ni, Cu, Zn, Mo, Ag, Pt, and Au and/or an alloy including at least two selected from the group consisting of Al, Ni, Cu, Zn, Mo, Ag, Pt, and Au. The metal electrode layer  17  may be formed to have a thickness at 0.01 μm or 10 μm or between 0.1 μm and 100 μm. 
     Among the metals available for the metal electrode layer  17 , metal such as Al, which can form an oxide film through combination with oxygen at a normal temperature, forms an oxide film at the normal temperature as described above. Since a metal oxide film serves as a protection layer from the electrolyte solution  5  (see  FIG. 1 ), there is an advantage here that a process of forming a protection layer for an electrode can be omitted as compared with a conventional process. Also, since the processes are simplified, the price competitiveness of the photoelectric conversion device  1  can be more enhanced. 
     Hereinafter, processes of preparing an electrode for the photoelectric conversion device according to embodiments of the present invention will be described in more detail with reference to  FIGS. 5A to 5E  and  6 A to  6 D. 
       FIGS. 5A to 5E  are sectional views schematically showing processes of preparing an electrode for the photoelectric conversion device according to a first embodiment of the present invention.  FIGS. 6A to 6D  are sectional views schematically showing processes of preparing an electrode for the photoelectric conversion device according to a second embodiment of the present invention. 
     Hereinafter, the processes of preparing the electrode for the photoelectric conversion device according to the first embodiment of the present invention will be described with reference to  FIGS. 5A to 5E . 
     Referring to  FIGS. 5A and 5B , a first substrate  11  having a transparent conductive layer  13  formed thereon is fixed to a jig  10  mounted in a vacuum chamber  100 . Subsequently, a first mask M 1  having openings respectively corresponding to portions (or the pattern) of an intermediate electrode layer  15  is disposed on the transparent conductive layer  13 . 
     Also, deposition boats  130  are arranged on a ventilator  120  positioned opposite to (or opposing or facing) the jig  110  in the vacuum chamber  100 . An intermediate electrode forming material  15   a  is contained in the deposition boats  130 . 
     The ventilator  120  is operated, and the deposition boats  130  are heated to reach the temperature at which the intermediate electrode forming material  15   a  can be evaporated. The intermediate electrode forming material  15   a  evaporated as described above is deposited on the transparent conductive layer  13  through the openings of the first mask M 1 , thereby forming the intermediate electrode layer  15 . 
     Here, if the intermediate electrode layer  15  has reached a desired thickness, the deposition process of the intermediate electrode layer  15  is stopped. The intermediate electrode layer  15  may be formed to have a thickness desired by a user. However, in one embodiment, the intermediate electrode layer  15  is formed to have a thickness at 0.01 μm or 10 μm or between 0.01 μm and 10 μm. The intermediate electrode layer  15  may include at least one selected from the group consisting of Ti, Cr, Ni, Nb, Mo, Sn, Ta, W, Pt, Au, sus, ITO, FTO, ZnO, SnO(II), and SnO 2 (IV) and/or an alloy including at least two selected from the group consisting of Ti, Cr, Ni, Nb, Mo, Sn, Ta, W, Pt, Au, sus, ITO, FTO, ZnO, SnO(II), and SnO 2 (IV). 
     Subsequently, as shown in  FIGS. 5C and 5D , a second mask M 2  having openings respectively corresponding to (or matching) the pattern (or positions of the portions) of the intermediate electrode layer  15  is disposed on the intermediate electrode layer  15  deposited in the previous process. In this embodiment, the second mask M 2  is shown (or labeled) to be different from the first mask M 1 . However, in another embodiment, the identical first mask M 1  is used without the need of the second mask M 2  (but moved to provide a set gap between the mask and the intermediate electrode layer  15 ). Here, in one embodiment, the set gap matches a desired thickness of the metal electrode layer  17 . 
     As described in the previous process, the deposition boats  130  are arranged on the ventilator  120  positioned opposite to the jig  110  in the vacuum chamber  100 . However, a metal electrode forming material  17   a  is contained in the deposition boats  130 . 
     Similarly, the ventilator  120  is operated, and the deposition boats  130  are heated to reach the temperature at which the metal electrode forming material  17   a  can be evaporated. The metal electrode forming material  17   a  evaporated as described above is deposited on the intermediate electrode layer  15  through the openings of the second mask M 2 , thereby forming the metal electrode layer  17 . 
     Here, if the metal electrode layer  17  has reached a desired thickness, the deposition process of the metal electrode layer  17  is stopped. The metal electrode layer  17  may be formed to have a thickness desired by a user. However, in one embodiment, the intermediate electrode layer  15  is formed to have a thickness at 0.01 μm or 10 μm or between 0.1 μm and 100 μm. The metal electrode layer  17  may include at least one selected from the group consisting of Al, Ni, Cu, Zn, Mo, Ag, Pt, and Au, and/or an alloy including at least two selected from the group consisting of Al, Ni, Cu, Zn, Mo, Ag, Pt, and Au. 
     Finally, as shown in  FIG. 5E , the second mask M 2  disposed on the metal electrode layer  17  is removed, and the first substrate  11  is separated from the jig  110 , thereby completing the first electrode  10  for the photoelectric conversion device  1 . In the first electrode  10  for the photoelectric conversion device  1 , the intermediate electrode layer  15  and the metal electrode layer  17  are continuously deposited and formed on the first substrate  11  so that adhesion is enhanced. 
     Hereinafter, the processes of preparing the electrode for the photoelectric conversion device according to the second embodiment of the present invention will be described with reference to  FIGS. 6A to 6D  in more detail. 
     Referring to  FIGS. 6A and 6B , a first substrate  11  having a transparent conductive layer  13  formed thereon is fixed to a jig  10  mounted in a vacuum chamber  100 . Subsequently, a mask M 1  having an opening (or openings) corresponding or overlapping with the pattern (or portions) of the transparent conductive layer  13  is disposed on the transparent conductive layer  13 . 
     Also, deposition boats  130  are arranged on a ventilator  120  positioned opposite to (or opposing or facing) the jig  110  in the vacuum chamber  100 . An intermediate electrode forming material  15   a  is contained in the deposition boats  130 . 
     The ventilator  120  is operated, and the deposition boats  130  are heated to reach the temperature at which the intermediate electrode forming material  15   a  can be evaporated. The intermediate electrode forming material  15   a  evaporated as described above is deposited on the transparent conductive layer  13  through the opening(s) of the mask M 1 ′, thereby forming a preliminary intermediate electrode layer  15 P. 
     Here, if an intermediate electrode layer  15  to be formed later has reached a desired thickness, the deposition process of the preliminary intermediate electrode layer  15 P is stopped. The preliminary intermediate electrode layer  15 P may be formed to have a thickness desired by a user. However, in one embodiment, the preliminary intermediate electrode layer  15 P is formed to have a thickness at 0.01 μm or 10 μm or between 0.01 μm and 10 μm. The preliminary intermediate electrode layer  15 P may include at least one selected from the group consisting of Ti, Cr, Ni, Nb, Mo, Sn, Ta, W, Pt, Au, sus, ITO, FTO, ZnO, SnO(II), and SnO 2 (IV) and/or an alloy including at least two selected from the group consisting of Ti, Cr, Ni, Nb, Mo, Sn, Ta, W, Pt, Au, sus, ITO, FTO, ZnO, SnO(II), and SnO 2 (IV). 
     Subsequently, as shown in  FIG. 6C , the ventilator  120  is continuously operated, and the deposition boats  130  are heated to reach the temperature at which a metal electrode forming material  17   a  can be evaporated. The metal electrode forming material  17   a  evaporated as described above is deposited on the preliminary intermediate electrode layer  15 P through the opening(s) of the mask M 1 , thereby forming a preliminary metal electrode layer  17 P. 
     Subsequently, as shown in  FIG. 6D , the mask M 1 ′ disposed on the preliminary metal electrode layer  17 P is removed, and the first substrate  11  is separated from the jig  110 . Finally, the preliminary intermediate electrode layer  15 P and the preliminary metal electrode layer  17 P are etched, thereby completing the first electrode  10  for the photoelectric conversion device  1 . In the first electrode  10  for the photoelectric conversion device  1 , the intermediate electrode layer  15  and the metal electrode layer  17  are continuously deposited and formed on the first substrate  11  so that adhesion is enhanced. 
     As described above, according to the embodiments of the present invention, the price competitiveness of the photoelectric conversion device can be enhanced by replacing a conventional electrode material. 
     Also, the adhesion between the metal electrode layer and the transparent conductive layer is increased due to the intermediate electrode layer interposed between the transparent conductive layer and the metal electrode layer, so that it is possible to prevent (or protect from) a phenomenon that the electrolyte solution is penetrated into the interface between the transparent conductive layer and the metal electrode layer, and therefore, the metal electrode layer gets loose. Accordingly, it is possible to increase the photoelectric conversion efficiency of the photoelectric conversion device and to enhance the reliability of the photoelectric conversion device. 
     While the present invention has been described in connection with certain exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, and equivalents thereof.