[DESCRIPTION]
[Invention Title]
DYE-SENSITIZED SOLAR CELL AND METHOD FOR MANUFACTURING
SAME
[Technical Field]
The present specification relates to a dye-sensitized solar cell and a fabrication
method thereof.
[Background Art]
Crystalline silicon solar cells have been widely known as a device for directly
converting light energy into electric energy. The crystalline silicon solar cells are used as an
independent power source, and as a power source for use in a vehicle. The crystalline
silicon solar cells are made usually of silicon single crystals or amolphous silicon. However,
enormous amounts of energy is required to produce silicon single crystals or amorphous
silicon, and in order to recover energy consumed for fabricating the solar cells, the solar cells
needs to generate electric power continuously for nearly a ten-year long period.
On the contrary, dye-sensitized solar cells have been proposed as an inexpensive solar
cell. The dye-sensitized solar cells have been expected to serve as the next-generation solar
cell due to a simple fabrication neth hod and a reduction in material costs. As illustrated in
the following FIG. 16, for example, a dye-sensitized solar cell in the related art comprises a
transparent conductive electrode 503, a porous semiconductor layer 102 comprising a dye
sensitizer 102a supported therein, a counter electrode 505, and an electrolyte material 107
provided between the transparent conductive electrode 503 and the counter electrode 505.
[Detailed Descriptioi1 of the Invention]
[Technical Problem]
The prescl~tin vention has been made in an effort to provide a dye-sensitized solar cell
having excellent power conversion efficiency and a fabrication method thereof.
[Technical Solution]
The present invention provides a dye-sensitized solar cell comprising:
a transparent substrate;
a porous semiconductor layer provided on the transparent substrate and comprising a
dye sensitizer;
a current collecting electrode provided on the porous semiconductor layer and
deposited such that a structure having at least one through-hole on the porous semiconductor
layer is formed;
a catalyst electrode; and
an electrolyte material provided between the transparent substrate and the catalyst
electrode.
Further, the present invention provides a dye-sensitized solar cell comprising:
a transparent substrate;
a first porous semiconductor layer provided on the transparent substrate and
comprising a first dye sensitizer;
a current collecting electrode provided on the first porous semiconductor layer;
a second porous semiconductor layer provided on the current collecting electrode and
comprising a second dye sensitizer;
a catalyst electrode; and
an electrolyte material provided between the transparent substrate and the catalyst
electrode.
In addition, the present invention provides a method for fabricating a dye-sensitized
solar cell, the method comprising:
preparing a transparent substrate;
for~ninga porous semiconductor layer on the transparent substrate;
depositing a current collecting electrode on the porous semiconductor layer such that
a structure having at least one through-hole on the porous semiconductor layer is formed;
introducing a dye sensitizer into the porous semiconductor layer;
forming a catalyst electrode; and
introducing an electrolyte material between the transparent substrate and the catalyst
electrode.
Furthermore, the present invention provides a method for fabricating a dye-sensitized
solar cell, the method comprising:
preparing a transparent substrate;
forming a first porous semiconductor layer on the transparent substrate;
depositing a first current collecting electrode on the first porous semiconductor layer;
introducing a dye sensitizer into the porous semiconductor layer;
forming a second porous semiconductor layer on the first current collecting electrode;
introducing a second dye sensitizer into the second porous semiconductor layer;
forming a catalyst electrode; and
introducing an electrolyte material between the transparent substrate and the catalyst
electrode.
[Advantageous Effects]
The dye-sensitized solar cell according to the present invention may enhance the
collection of photogenerated electrons from a porous semiconductor layer by improving the
contact of the porous semiconductor layer with a current collecting electrode, thereby
improving the power conversion efficiency thereof. Further, the method for fabricating a
dye-sensitized solar cell according to the present invention may be easily applied to a dyesensitized
solar cell comprising a plurality of semiconductor layers.
[Brief Description of Drawings]
FIG. 1 is a view schematically illustrating a dye-sensitized solar cell according to a
first exemplary embodiment of the present invention.
FIG. 2 is a view illustrating an SEM photograph of the upper portion of a porous
semiconductor layer (Ti02).
FIG. 3 is a view illustrating an SEM photograph of a slanted side of a current
collecting electrode which is partially peeled-off from the porous semiconductor layer.
FIG. 4 is a view illustrating an SEM photograph of the upper portion of a current
collecting electrode.
FIG. 4 is a view schematically illustrating a current collecting electrode formed on
the porous semiconductor layer.
FIG. 6 is a view schematically illustrating a dye-sensitized solar cell according to a
second exemplary embodiment of the present invention.
FIG. 7 is a view schematically illustrating a dye-sensitized solar cell according to a
third exemplary embodiment of the present invention.
FIG. 8 is a view schematically illustrating a dye-sensitized solar cell according to a
fourth exemplary embodiment of the present invention.
FIG. 9 is a view schematically illustrating a dye-sensitized solar cell according to a
fifth exemplary embodiment of the present invention.
FIG. 10 is a view schematically illustrating a dye-sensitized solar cell according to a
sixth exemplary embodiment of the present invention.
FIG. 1 I is a view schematically illustrating a dye-sensitized solar cell according to a
seventh exemplary embodiment of the present invention.
FIG. 12 is a view schematically illustrating a dye-sensitized solar cell according to an
eighth exemplary embodiment of the present invention.
FIG. 13 is a view schematically illustrating a dye-sensitized solar cell according to a
ninth exemplary embodiment of the present invention.
FIG. 14 is a view schematically illustrating a dye-sensitized solar cell according to a
tenth exemplary embodiment of the present invention.
FIG. 15 is a view schematically illustrating a dye-sensitized solar cell according to an
eleventh exemplary embodiment of the present invention.
FIG. 16 is a view schematically illustrating a dye-sensitized solar cell in the related
art.

003 : Transparent current collecting electrode
10 1 : Transparent substrate
102: Porous semiconductor layer
202: Second porous semiconductor layer
302: Third porous semiconductor layer
102a, 202a, 302a: Dye sensitizer
103 : Current collecting electrode
203 : Second current collecting electrode
303: Third current collecting electrode
103b, 203b, 303b: Through-hole
104: Sealing spacer
104: Internal spacer
105: Catalyst electrode
106: Second substrate
107: Electrolyte material
503: Transparent conductive electrode
505: Counter electrode
[Best Mode]
Hereinafter, preferred exemplary embodiments of the present invention will be
described in detail with reference to the accompanying drawings.
FIG. 1 is a view schematically illustrating a dye-sensitized solar cell according to a
first exemplary embodiment of the present invention. The dye-sensitized solar cell
according to the first exemplary embodiment comprises a transparent substrate 10 1, a porous
semiconductor layer 102 comprising a dye sensitizer 102a, a current collecting electrode 103
provided on the porous semiconductor layer 102 and deposited such that a structure having at
least one through-hole 103b on the porous semiconductor layer 102 is formed, a sealing
spacer 104, a catalyst electrode 105, a second substrate 106, and an electrolyte material 107
comprised between the transparent substrate 10 1 and the catalyst electrode 105.
The transparent substrate 10 1 may be a glass substrate, a plastic substrate, a ceramic
substrate, and the like. Preferably, the transparent substrate 101 has a light transmittance of
at least 10% or more. The thickness of the transparent substrate is not particularly limited as
long as the transparent substrate has appropriate strength and transparency which are
permitted for the solar cell. Examples of the glass comprise soda glass, borosilicate glass,
aluminosilicate glass, aluminoborosilicate glass, silica glass, soda lime glass, and the like.
Examples of the plastic substrate comprise polyester sheet such as polyethylene terephthalate
and polyethylene naphthalate, and sheet such as polyphenylene sulfide, polycarbonate,
polysulfone, and polyethylidene norbomene. Examples of the ceramic comprise high-purity
alumina, and the like. Among the examples of the transparent substrate, the glass substrate
is preferred due to stability and operability.
Before forming the porous semiconductor layer 102 on the transparent substrate 101,
it is possible to perform pre-treatments that reinforce bonding strength, such as semiconductor
layer material pre-treatment using a semiconductor material precursor solution, plasma
treatment, ozone treatment, and chemical treatment. By the result of the semiconductor
material pre-treatment, a pre-treatment layer (semiconductor thin film) is formed on the
transparent substrate 10 1. For example, it is preferred that the thickness of the pre-treatment
layer is 0.1 nrn to 50 nm, particularly 0.2 nm to 25 nm.
The porous semiconductor layer 102 is formed on the transparent substrate 101 or the
pre-treatment layer. The porous semiconductor layer may comprise a semiconductor
material which is generally used in photoelectric conversion. Examples of the
semiconductor material for the pre-treatment and the porous semiconductor layer 102
comprise titanium oxide, zinc oxide, tin oxide, niobium oxide, zirconium oxide, cerium oxide,
tungsten oxide, silicon oxide, aluminum oxide, nickel oxide, tantalum oxide, barium titanate,
strontium titanate, calcium titanate, zinc sulfide, lead sulfide, bismuth sulfide, cadmium
sulfide, CuA102, SrCu202, and the like. These materials may be used either alone or in
combination thereof. The porous semiconductor layer may have a form of particle, rod, tube,
wire, needle, film, or combination thereof.
Among the aforementioned examples of the semiconductor material, titanium oxide is
preferred due to stability and safety. Examples of the titanium oxide comprise anatase type
titanium oxide, rutile type titanium oxide, amorphous titanium oxide, metatitanic acid,
orthotitanic acid, titanium hydroxide, hydrated titanium oxide, and the like.
The fabrication method of the porous semiconductor layer 102 is not particularly
limited. For example, the porous semiconductor layer 102 may be fabricated by applying a
paste comprising a semiconductor material having a form of particle, rod, tube, wire, or
needle on the transpareilt substrate 101, and then sintering the paste. The application process
of the paste is also not particularly limited, and it is possible to apply a screen printing process,
a doctor blade process, a squeegee process, a spin-coat process, a spray coat process, an inkjet
printing process, a gravure coat process, a chemical vapor deposition (CVD) method, a metalorganic
chemical vapor deposition (MOCVD) method, a physical vapor deposition (PVD)
method, a deposition method, a sputtering method, a sol-gel method, and the like. The
porous semiconductor layer 102 may also be formed by transferring an alignment layer onto
the transparent substrate 101 with a semiconductor material having a form of rod, tube, wire,
or needle.
It is preferred that an average particle diameter of semiconductor particles used to
form the porous semiconductor layer 102 ranges, for example, from 1 nm to 400 nm,
particularly from 5 nm to 100 nm. Here, the particle diameter is determined by an SEM
photograph after the porous semiconductor layer 102 is formed on the transparent substrate
10 1, as illustrated in the following FIG. 2.
The thickness of the porous semiconductor layer 102 is not particularly limited, and
may be controlled to 0.1 pm to 100 pm, particularly I pm to 75 pm. In addition, it is
preferred that the porous semiconductor layer 102 is subjected to heat treatment in order to
remove a solvent and organic materials and increase the strength of the porous semiconductor
layer 102 and adhesion between the porous semiconductor layer 102 and the transparent
substrate 101. The temperature and time of the heat treatment are not particularly limited.
It is preferred that the heat treatment temperature is controlled to 30°C to 700°C, particularly
70°C to 600°C, and that the heat treatment time is controlled to 5 minutes to 10 hours,
particularly 10 minutes to 6 hours.
The current collecting electrode 103 is coated on the porous semiconductor layer 102
in order to collect electrons from the porous semiconductor layer 102 and release electrons to
the outside of the solar cell. The material for the current collecting electrode 103 is not
particularly limited, and a metal, a conductive oxide, a carbon material, a conductive polymer,
and the like may be applied. Examples of the metal comprise titanium, nickel, platinum,
gold, silver, copper, aluminum, tungsten, rhodium, indium, and the like. Examples of the
conductive oxide comprise tin oxide, fluorine-doped tin oxide (FTO), indium oxide, tin-doped
indium oxide (ITO), zinc oxide, and the like. Examples of the carbon material comprise
carbon nanotubes, graphene, carbon black, and the like. Examples of the conductive
polymer comprise poly(3,4-ethy1enedioxythiophene):polystyrene sulfonate (PEDOT-PSS),
polypyssole, polyaniline, poly-3,4-ethylenedioxythiophene (poly-EDT), and the like. These
materials may be used either alone or in combination thereof. The material is more
preferably a conductive metal.
The current collecting electrode 103 is coated on the porous semiconductor layer 102
by a deposition method. As illustrated in the following FIG. 3, a part or whole of the current
collecting electrode 103 may be embedded in the porous semiconductor layer 102. The
current collecting electrode 103 may be formed by depositing a conductive material such as a
metal, a conductive oxide, a carbon material, and a conductive polymer on the porous
semiconductor layer 102 by physical vapor deposition such as thermal metal evaporation,
electron beam evaporation, RF sputtering, magnetron sputtering, atomic layer deposition, arc
vapor deposition, and ion beam assisted deposition, or a chemical vapor deposition process
such as CVD, MOCVD, and plasma-enhanced chemical vapor deposition (PECVD). The
deposition process is controlled such that a porous structure having at least one through-hole
is formed on the porous semiconductor layer. In order to obtain good conductivity
throughout the entire surface of the current collecting electrode, the current collecting
electrode may have a porous structure comprising a sheet form and through-holes. It is
preferred that the porous structure of the current collecting electrode 103 is simply formed by
a deposition method instead of other materials such as a pore forming auxiliary agent.
When a conductive material is deposited in order to form the current collecting
electrode 103, a topographical form may depend on a surface topographical form of the
porous semiconductor layer 102. For example, a rough surface having many through-holes
may be formed on a rough surface such as the porous semiconductor layer 102. As
illustrated in the following FIG. 4, when a conductive material such as aluminum is deposited
on a porous semiconductor layer (Ti02), the surface of the aluminum layer may be very rough
substantially similar to the surface of the porous semiconductor layer, while having many
through-holes. However, as illustrated in the following FIG. 4, when the aluminum layer is
deposited on a glass substrate, the surface of the aluminum layer may be smooth and dense
without having a through-hole. Here, when the current collecting electrode 103 is coated on
the surface of the rough porous semiconductor layer 102, the surface of the current collecting
electrode may also have a rough surface substantially similar to the topographical form of the
surface of the porous semiconductor layer 102, as illustrated in the following FIG. 5.
Therefore, the contact area between the current collecting electrode and the porous
semiconductor layer may be maximized, and the power conversion efficiency of the solar cell
may be increased. Furthermore, by forming the surface of the current collecting electrode to
be substantially the same as the topographical form of the surface of the porous
semiconductor layer, the current collecting electrode may comprise at least one through-hole
without a separately additional treatment such as patterning or a pore forming auxiliary agent.
In order to obtain the current collecting electrode 103 having substantially the same
topographical form as that of the surface of the porous semiconductor layer 102, it is preferred
that the thickness of the current collecting electrode is controlled to a range from 5 nm to
1,000 nm using the above-described fabrication method.
According to the present invention, in order to form the current collecting electrode
103 having at least one through-hole, physical vapor deposition of a metal or a conductive
oxide is preferably applied. For the deposition of the metal, aluminum, titanium, nickel,
platinum and/or tungsten are preferably applied. For the deposition of the conductive oxide,
fluorine-doped tin oxide (FTO) and tin-doped indium oxide (ITO) are preferably applied.
In the case of physical vapor deposition of a metal or a conductive oxide, the number
of through-holes of the current collecting electrode 103 may be controlled by changing a
deposition rate, and the deposition rate may be controlled to 0.01 nm/sec to 50 nmlsec. The
deposition rate of the current collecting electrode 103 is preferably 0.05 nmlsec to 25 nmlsec.
When the deposition rate of the current collecting electrode 103 is 0.01 nmlsec to 50 nmlsec,
it is possible to fabricate the current collecting electrode 103 having at least one through-hole.
In the case of physical vapor deposition of a metal or a conductive oxide, the number
of through-holes of the current collecting electrode 103 is not particularly limited as long as
the number of through-holes allows a photosensitizing dye solution and an electrolyte
material to be permeated. The number of through-holes of the current collecting electrode
103 may be 0.01 hole/mm2 to lo9 hole/mm2, preferably 0.1 hole/mm2 to 10' hole/mm2, and
more preferably 1 hole/mm2 to lo7 hole/mm2.
In the case of physical vapor deposition of a inetal or a conductive oxide, the
diameter of through-holes in the current collecting electrode 103 is not particularly limited.
The diameter of through-holes in the current collecting electrode 103 may be 1 nm to lo5 nm,
preferably 3 nm to 1 o4 nm, and more preferably 5 nm to 1 o3 nm.
In the case of physical vapor deposition of a metal or a conductive oxide, the
thickness of the current collecting electrode 103 is an important element. A thick film does
not form a through-hole and a thin film does not have sufficient conductivity for collecting
electrons from the porous semiconductor layer 102. The film thickness of the current
collecting electrode 103 may be 5 nm to 1,000 nm, preferably 8 nm to 500 nm, and more
preferably 12 nm to 300 nm. When the film thickness of the current collecting electrode 103
is less than 5 nm, conductivity of the current collecting electrode may be too low to be used as
a current collecting electrode. On the contrary, when the film thickness of the current
collecting electrode 103 exceeds 1,000 nm, there may occur a problem in that through-holes
are too small for a dye solution and an electrolyte solution to be permeated via the throughholes.
The current collecting electrode may or may not be transparent. When an additional
porous semiconductor layer 202 or 302 is provided on the current collecting electrode, it is
preferred that the current collecting electrode 103 or 203 is transparent such that irradiated
light reaches the additional porous semiconductor layer through the transparent current
collecting electrode (FIGS. 6 to 9). When the current collecting electrode is transparent, the
current collecting electrode 103 may be formed in the form of a thin film made of a metal, a
conductive oxide, or a carbon material.
When the current collecting electrode 103 is transparent, the second porous
semiconductor layer 202 may be formed on the current collecting electrode 103, as illustrated
in the following FIG. 6. In the structure, more electrons may be collected from the two
porous semiconductor layers 102 and 202 caused by an increased contact area between the
current collecting electrode 103 and the two porous semiconductor layers 102 and 202,
thereby obtaining high power conversion efficiency. At this time, the second porous
semiconductor layer 202 may physically separate the current collecting electrode 103 from
the catalyst electrode 105, thereby making it unnecessary to have a spacer between the current
collecting electrode 103 and the catalyst electrode 105.
In order to utilize different wavelength ranges from irradiated light, it is possible to
use different dye sensitizers 102a and 202a on the porous semiconductor layers 102 and 202,
respectively. As illustrated in the following FIG. 7, in order to additionally increase the
contact area between the current collecting electrode and the porous semiconductor layer, the
second current collecting electrode 203 may be formed on the second porous semiconductor
layer 202. The second current collecting electrode 203 may be generally transparent, but
may not be transparent. Likewise, in order to increase the power conversion efficiency, as
illustrated in the following FIG. 8, the third porous semiconductor layer 302 may be formed
on the second current collecting electrode 203, and as illustrated in the following FIG. 9, a
third current collecting electrode 303 may be formed on the third porous semiconductor layer
302. In the structures of the following FIGS. 8 and 9, in order to utilize different wavelength
ranges from irradiated light, it is possible to use different dye sensitizers 102a, 202a, and 302a
on the porous semiconductor layers 102,202, and 302, respectively.
After the conductive material is deposited, a heat treatment may be performed. As
described above, the current collecting electrodes 103, 203, and 303 having at least one
through-hole 103b, 203b, or 303b may be formed on the porous semiconductor layers 102,
202, and 302 by simple physical vapor deposition or chemical deposition of a conductive
material, and after the deposition, no mask or photolithography process may be used.
The dye sensitizers 102a, 202a, and 302a may be dye sensitizers having an
absorbance in a wide range of a visible light region and/or an IR region, and may be, for
example, organic dyes, metal complex dyes, and the like. Examples of the organic dyes
comprise azo type dyes, quinone type dyes, quinone-imine type dyes, quinacridone type dyes,
squarylium type dyes, cyanine type dyes, merocyanine type dyes, triphenylmethane type dyes,
xanthene type dyes, porphyrin type dyes, perylene type dyes, indigo type dyes, and
naphthalocyanine type dyes. Examples of the metal complex dyes comprise phthalocyanine
type dyes and ruthenium type dyes, comprising, as a dominant metal, a metal such as Cu, Ni,
Fe, Co, V, Sn, Si, Ti, Ge, Cr, Zn, Ru, Mg, Al, Pb, Mn, In, Mo, Y, Zr, Nb, Sb, La, W, Pt, Ta, Is,
Pd, Os, Ga, Tb, Eu, Rb, Bi, Se, As, Sc, Ag, Cd, Hf, Re, Au, Ac, Tc, Te, and Rh.
Further, it is preferred that the dye sensitizers 102a, 202a, and 302a comprise a
functional group for bonding to the porous semiconductor layers 102, 202, and 302.
Exa~nples of the functional group comprise a carboxyl group, an alkoxy group, a hydroxyl
group, a sulfonic acid group, an ester group, a mercapto group, or a phosphonyl group.
Among them, ruthenium complex dyes are more preferred. In the dye-sensitized solar cell,
the dye sensitizers 102a, 202a, and 302a may be the same as or different from each other. In
order to extend a photoelectric conversion wavelength range of the dye sensitizer and thereby
improving photoelectric conversion efficiency, two or more kinds of sensitizing dye
compounds having different photoelectric conversion wavelength ranges may be used in
combination. In this case, it is possible to select and apply the types and quantity ratio of the
dye sensitizer compounds according to the wavelength range and intensity distribution of
irradiated light.
Before the dye sensitizer 102a is adsorbed in the porous semiconductor layer 102, for
activation of the surface of the porous semiconductor layer and/or an increase in the surface
area thereof, it is possible to perform a post-treatment such as a semiconductor material posttreatment
using a semiconductor material precursor solution, a heat treatment, a plasma
treatment, an ozone treatment, and a chemical treatment. Examples of the semiconductor
material for the post-treatment comprise titanium oxide, zinc oxide, tin oxide, niobium oxide,
zirconium oxide, cerium oxide, tungsten oxide, silicon oxide, aluminum oxide, nickel oxide,
tantalum oxide, barium titanate, strontium titanate, calcium titanate, zinc sulfide, lead sulfide,
bismuth sulfide, cadmium sulfide, CuA102, SrCu2OZ, and the like. As a result of the
semiconductor material post-treatment, a post-treatment layer (semiconductor thin film) is
formed on the porous semiconductor layer 102. For example, it is preferred that the
thickness of the post-treatment layer is 0.1 nm to 50 nm, particularly 0.2 nm to 25 nm.
The dye sensitizer 102a may be adsorbed in the porous semiconductor layer 102 by
immersing the porous semiconductor layer 102 coated with the current collecting electrode
103 in a solution comprising the dye sensitizer. The solution comprising the dye sensitizer
may be permeated into the porous semiconductor layer 102 via the through-hole 103b of the
current collecting electrode 103. The solution is not particularly limited as long as the dye
sensitizer may be dissolved therein. Examples of the solution comprise organic solvents
such as alcohol, toluene, acetonitrile, chloroform, and dimethylformamide. In general, these
solvents are preferably purified ones. ']The concentration of the dye sensitizer in the solvent
may be controlled depending on the types of dye and solvent used and the conditions of the
step of adsorbing the dye sensitizer, and is preferably 1 x lop5 moll1 or more.
In the immersion process of the porous semiconductor layer 102 in the solution
comprising the dye sensitizer, the temperature, pressure, and time may be varied, if necessary.
The immersion process may be performed once or a plurality of times, and after the
immersion process, a drying process may be properly performed.
In the dye-sensitized solar cell according to the present invention, in order to prevent
the loss of the electrolyte material 107 and maintain a proper space between the current
collecting electrode 103 and the catalyst electrode 105, the sealing spacer 104 may be used
between the transparent substrate 101 or the current collecting electrode 103 and the second
substrate 106 or the catalyst electrode 105. The sealing spacer 104 may be formed of a
thermoplastic film, a resin, glass, or the like. Examples of the thermoplastic film comprise
commercially available SurlynO resins, BynelB resins, and the like. Examples of the resin
comprise photocurable resins such as thermosetting resins, epoxy resins, urethane resins, and
polyester resins. In particular, hot-melt SurlynB resin which may be easily controlled is
preferred. When the solar cell requires long-term durability, it is preferred that the sealing
spacer 104 is formed of glass. Of course, when the porous semiconductor layers 202 and
302 are provided between the current collecting electrodes 103 and 203 and the catalyst
electrode 105, electrical contact may be avoided even when there is no spacer.
As long as the electrical contact may be prevented between the current collecting
electrode 103 and the catalyst electrode 105, the thickness of the sealing spacer 104 is not
1
particularly limited. After the sealing spacer 104 is applied, the thickness of gap between the
current collecting electrode 103 and the catalyst electrode 105 may be 0.1 mm to 1,000 mm,
preferably 1 mm to 500 mm, and more preferably 5 mm to 100 mm.
As illustrated in the following FIG. 10, one or more internal spacer 104' may be used
between the current collecting electrode 103 and the catalyst electrode 105, if necessary.
The number and form of the internal spacers 104' is not particularly limited. The larger the
area of the porous semiconductor layer 102 is, the more the internal spacers 104' may be
required. The internal spacer 104' may be provided in the shape of a sphere, a cylinder, a
prism, a line (for example, strip type or bar type), and the like. The sealing spacer 104 may
be made of a thermoplastic film, a resin, glass, or the like.
The catalyst electrode 105 may be made of a catalytically active material, or at least
one of a metal, a conductive oxide, and a resin, which comprise a catalytically active material
therein. Examples of the catalytically active material comprise noble metals such as
platinum and rhodium, and carbon black. These materials may also have conductivity. It is
preferred that the catalyst electrode 105 is formed of a noble metal having catalytic activity
and electrochemical stability. In particular, it is possible to preferably apply platinum which
has high catalytic activity and is less likely to be dissolved in an electrolyte solution.
When a metal, a conductive oxide, or a conductive resin exhibiting no catalytic
activity is used, it is preferred that a catalytically active material is comprised in the materials.
Examples of the metal comprise aluminum, copper, chromium, nickel, tungsten, and the like,
and examples of the conductive resin comprise polyaniline, polypyrrole, polyacetylene,
PEDOT-PSS, poly-EDT, and the like. These conductive materials may be used either alone
or in combination thereof.
The catalyst electrode 105 may be formed by depositing a material having catalytic
activity and electrical conductivity on the second substrate 106. Otherwise, a metal layer, a
conductive oxide layer or a conductive resin layer exhibiting no catalytic activity may be
formed on the second substrate 106, and then a catalytically active material may be
successively deposited thereon.
The second substrate 106 may or may not be transparent. As long as the second
substrate 106 is tough enough to provide a dye-sensitized solar cell which supports a substrate
and has high durability, the second substrate 106 is not particularly limited. The second
substrate 106 may be glass, plastic, metal, ceramic, or the like. Examples of the plastic
substrate comprise polyester, polyphenylene sulfide, polycarbonate, polysulfone,
polyethylidene norbornene, and the like. Examples of the metal substrate comprise tungsten,
titanium, nickel, platinum, gold, copper, and the like. Examples of the ceramic substrate
comprise alumina, mullite, zirconia, silicon nitride, sialon, titanium nitride, aluminum nitride,
silicon carbide, titanium carbide, aluminum carbide, and the like.
The electrolyte material 107 may be provided between the porous semiconductor
layer 102 and the catalyst electrode 105 such that ionic conduction may be carried out
between the porous semiconductor layer 102 and the catalyst electrode 105. The electrolyte
material 107 may be prepared from an electrolyte solution. In general, the electrolyte
solution comprises a solvent and various additives in addition to the electrolyte material 107.
Examples of the electrolyte material 107 comprise: (1) 12 and an iodide; (2) Br2 and a
bromide; (3) a metal complex such as a ferrocyanide-ferricyanide complex, a ferroceneferricinium
ion complex, or a cobalt redox complex; (4) a sulfur compound such as sodium
polysulfide or alkylthiol-alkyldisulfide; (5) a viologen dye; and (6) hydroquinone-quinone.
In relation to the iodide of the electrolyte (I), there may be used metal iodides such as LiI,
NaI, KI, CsI and Ca12, quaternary ammonium iodides such as tetralkylammonium iodide,
pyridinium iodide and imidazolium iodide, and the like. In relation to the bromide of the
electrolyte (2), there may be used metal bromides such as LiRr, NaBr, KBr, CsBr, and CaBr2,
quaternary ammonium bromides such as tetralkylammonium bromide and pyridinium
bromide, and the like. Among these electrolyte materials, a combination of I2 and LiI or the
quaternary ammonium iodide such as pyridinium iodide or imidazolium iodide is more
preferred. These electrolyte materials may be used either alone or in combination thereof.
It is preferred that the solvent of the electrolyte solution is a solvent having low
viscosity, high ionic mobility, and sufficient ionic conductivity. Examples of the solvent
comprise: (1) carbonates such as ethylenelcarbonate and propylene carbonate; (2) heterocyclic
compounds such as 3-methyl-2-oxazolidinone; (3) ethers such as dioxane and diethyl ether;
(4) chain ethers such as ethylene glycol dialkylether, propylene glycol dialkylether,
polyethylene glycol dialkylether, and polypropylene glycol dialkylether; (5) monoalcohols
such as methanol, ethanol, ethylene glycol monoalkylether, and propylene glycol
monoalkylether; (6) polyalcohols such as ethylene glycol, propylene glycol, polyethylene
glycol, polypropylene glycol, and glycerin; (7) nitriles such as acetonitrile, glutarodinitrile,
methoxyacetonitrile, propionitrile, and benzonitrile; and (8) aprotic polar solvents such as
dimethylsulfoxide and sulfolane.
In the dye-sensitized solar cell in the related art as illustrated in the following FIG. 16,
it is known that the optimized thickness of the porous semiconductor layer is 12 pm to 15 pm.
When the thickness of the porous semiconductor layer is less than 12 pm, the amount of the
dye sensitizer adsorbed to the porous semiconductor layer is decreased and the dye sensitizer
absorbs lesser incident light, thereby decreasing the overall efficiency. On the contrary,
when the thickness of the porous semiconductor layer exceeds 15 pm, the amount of the dye
sensitizer adsorbed to the porous semiconductor layer is enough to absorb most of the incident
light. However, most of the electrons injected into a conduction band of a semiconductor
part disposed at an upper surface spaced from the first current collecting electrode 503 may be
lost by recombination thereof before being collected into the first current collecting electrode
503. Accordingly, when the thickness exceeds 15 pm, the overall efficiency is not improved
as the thickness of the semiconductor layer is increased.
In order to overcome the thickness limitation of the porous semiconductor layer, an
additional transparent current collecting electrode 003 may be comprised between the
transparent substrate 101 and the porous semiconductor layer 102 (FIGS. 1 1 to 15). The
additional transparent current collecting electrode 003 increases an electrical contact area
between the semiconductor layer and the current collecting electrode. Based on the structure,
the overall efficiency may be further improved even when the thickness of the porous
semiconductor layer exceeds 15 pm. Accordingly, the maximum efficiency of the dyesensitized
solar cell structure may be more enhanced than the structure in the related art as
illustrated in the following FIG. 16.
Hereinafter, the present invention will be described in more detail through the
Examples, but the scope of the present invention is not limited by the following Examples.

A dye-sensitized solar cell was fabricated by the following method.
(1) Fabrication of Transparent Substrate 101
As a transparent substrate for the dye-sensitized solar cell according to a first
exemplary embodiment of the present invention as illustrated in the following FIG. 1, a
microscope slide glass (Ted Pella, Inc., USA) having a size of 0.5 inch x 1 inch was used.
First, the microscope slide glass was washed with a washing solution using an ultrasonic bath
for 10 minutes, and then washed with water and isopropanol. In order to remove residual
organic contaminant materials, the microscope slide glass was heat-treated at 400°C in air for
15 minutes.
(2) Fabrication of Porous Semiconductor Layer 102
A paste comprising nano particles (Ti-Nanoxide T20, Solaronix, Switzerland) having
a diameter of 20 nm was doctor-bladed on the microscope slide glass to form a porous Ti02
semiconductor layer 102. A uniform film having a thickness of 9.3 +I- 0.2 pm was formed
by the one-time doctor-blading of the paste which had been sintered at 500°C for 30 minutes.
The film thickness was measured using a KLA Tencor P-10 profiles.
(3) Fabrication of Current Collecting Electrode 103
An aluminum film as the current collecting electrode 103 was deposited on the
porous Ti02 semiconductor layer 102 by performing thermal deposition (The BOC Edwards
Auto 500 resistance evaporation system) at a deposition rate of 1.7 nmlsec under 2 x 10'~
mbar. The thickness of the film measured with an SEM was 5 nm.
(4) Adsorption of Dye Sensitizer 102a in Porous Semiconductor Layer 102
The porous Ti02 semiconductor layer 102 comprising the current collecting electrode
103 was immersed in a cis-di(thiocyanato)-N,N'-bis(2,2-bipyridyl-4-carboxylic acid-4-
tetrabutylammonium carboxy1ate)ruthenium (11) (N-7 19 dye) solution in a 0.3 mM mixture of
acetonitrile and tertbutyl alcohol (volume ratio, 1 : I), and maintained at normal temperature
for 20 hours to 24 hours for complete adsorption of the sensitizer.
(5) Second Substrate 106
A microscope slide glass having a thickness of 1 mm and a size of 0.5 inch x 1 inch
was used as a second substrate 106. A hole (diameter from 0.1 mm to 1 mm) was perforated
on the second substrate 106 using an injector.
(6) Fabrication of Catalyst Electrode 105 on Second Substrate 106
A platinum film (thickness of 100 nm) was deposited on the microscope slide glass
106 having a size of 0.5 inch x 1 inch using DC magnetron sputtering (Denton DV 502A) at
normal temperature.
(7) Fabrication of Electrolyte Material 107
An electrolyte material 107 was prepared with a solution of 0.6 M BMII, 0.03 M 12,
0.10 M guanidinium thiocyanate, and 0.5 M 4-test-butylpyridine in a mixture of acetonitrile
and valeronitrile (volume ratio, 85 : 15).
(8) Dye-Sensitized Solar Cell Assembly
A transparent substrate comprising a porous Ti02 semiconductor layer and a catalyst
electrode was assembled as a sandwich type cell and sealed with hot-melt SurlynB spacer
(SX1170-60, Solaronix, Switzerland) having a thickness of 60 pm. Thereafter, the
electrolyte material was introduced through the hole on the second substrate 106 under
vacuum. Finally, the hole was sealed with a 60 pm hot-melt BynelO (SX1162-60, Solaronix,
Switzerland) and a cover glass (thickness of 0.1 mm).
(9) Evaluation of Characteristics of Dye-Sensitized Solar Cell
The device was evaluated using a class-A 450W Oriel@ Solar Simulator (Model
91 195-A) equipped with an AM 1.5 global filter. The electric power was controlled so as to
obtain an intensity of 100 mw/cm2 using a Newport radiometer.

In Examples 2 to 5, dye-sensitized solar cells having current collecting electrodes
with different thicknesses were fabricated in the same manner as in Example 1. As in
Example 1, a porous Ti02 semiconductor layer having a thickness of 9.3 pm +I- 0.2 pm was
used as the porous semicollductor layer 102 as in Example 1. The power conversion
efficiency is shown in the following Table 1.

Dye-sensitized solar cells were fabricated in the same manner as in Example 1,
except that the current collecting electrodes were fabricated on the Ti02 layer to have a
thickness of 2 nrn and 2,000 nm, respectively. The power conversion efficiency is shown in
the following Table 1.
First current
collecting
electrode
Aluminum film
Form of first
current
collecting
electrode
Topographical
morphology of first
Substantially the same
Power
conversion
current collecting
electrode
I Example 1 I having a thickness / Porous 1 as semiconductor 1 3.7%
efficiency
of5 nm
Aluminum film
I I of1,000nm 1 I layer I
layer
Substantially the same
Example 2
Example 3
Example 4
Example 5
I
Comparative
Example 1
Comparative
Example 2
having a thickness
of 20 nm
Aluminum film
having a thickness
of 50 nm
Aluminum film
having a thickness
of 500 nm
Aluminum film
having a thickness
Aluminum film
having a thickness
of 2 nm
Aluminum film
having a thickness
of 2,000 nm
Porous
Porous
Porous
Porous
Porous
I
No thsoughhole
Substantially the same
as semiconductor
layer
Flat surface
as semiconductor
layer
Substantially the same
as semiconductor
layer
Substantially the same
as semiconductor
layer
Substantially the same
as semiconductor
I
As call bee seen in the result of Table 1, the dye-sensitized solar cells (Examples 1 to
5) comprising the current collectii~g electrode having a thickness from 5 nin to 1,000 nm
exhibit higher power conversion efficiencies than those of Comparative Examples 1 and 2.
6.6%
7.2%
3.6%
2.1 %
I
In addition, according to the SEM photographs illustrated in the following FIGS. 3 and 4, it
can be seen that the current collecting electrodes of the dye-sensitized solar cells according to
Examples 1 to 5 have through-holes and substantially the same topographical morphology as
that of the surface of the porous semiconductor layer.

A dye-sensitized solar cell was fabricated in the same manner as Example 1, except
that a microscope slide glass was pre-treated with Tic14 in order to improve adhesion force.
At this time, the pre-treatment was performed using a pre-treatment method of a
semiconductor material using a semiconductor material precursor solution between the
transparent substrate 101 and the porous semiconductor layer 102, and a 50 nm aluminum
film was used as the cursent collecting electrode 103. The pre-treatment using the Tic14
precursor solution was perfosmed as follows. The microscope slide glass plate was
immersed in a 40 mM TiC14 aqueous solution at 70°C for 30 minutes, washed with water and
ethanol, and dried with N2 gas at high pressure. The power conversion efficiency of the
solar cell according to Example 6 was 7.3% similar to Example 3. However, when
compared to Example 3, the porous semiconductor layer 102 on the transparent substrate 101
was very stable without any peeling off.

A dye-sensitized solar cell was fabricated in the same manner as in Example 1, except
that a 50 nrn-nickel film was used as the current collecting electrode 103. Nickel was
deposited on a Ti02 semiconductor layer having a thickness of 9.3 pm +I- 0.2 pm using
magnetron sputtering at normal temperature instead of using aluminum. The power
conversion efficiency is shown in the following Table 2.

A dye-sensitized solar cell was fabricated in the same manner as in Example 1, except
that a 50 nm-titanium film was used as the current collecting electrode 103. Titanium was
deposited on a Ti02 semiconductor layer having a thickness of 9.3 ym +I- 0.2 pm using
magnetron sputtering at normal temperature instead of using aluminum. The power
conversion efficiency is shown in the following Table 2.

A dye-sensitized solar cell was fabricated in the same manner as in Example 9, except
that a 7 nrn-titanium film was used as a first current collecting electrode 103, an additional
second porous Ti02 semiconductor layer (thickness of 7 pm) was formed on the first cursent
collecting electrode, and an additional second current collecting electrode 203 was formed on
the second porous Ti02 semiconductor layer. Here, the material and fabrication method of
the second porous Ti02 semiconductor layer are the same as the material and fabrication
method of the porous semiconductor layer as described in Example 1. The power
conversion efficiency is shown in the following Table 2.
[Table 21
Example 7
Example 8
Example 9
1 First semiconductor
layer
Nickel film having a
thickness of 50 nm
First current
collecting electrode
Titanium film
having a thickness of
50 nm
Second
semiconductor
layer
Power
conversion
efficiency
Titanium film
having a thickness of
7 nm
Ti02 having a
thickness of 7 ym
8.2%
A dye-sensitized solar cell was fabricated in the same manner as in Example 8, except
that after the current collecting electrode 103 as a 50 nm-titanium film was deposited, the
porous semiconductor layer 102 was subjected to post-treatment with Tic14 by a pre-treatment
method of a semiconductor material using a semiconductor material precursor solution in
order to improve adsorption of a dye and increase the surface area of the porous
semiconductor layer 102. The post-treatment using the Tic14 precursor solution was
performed as follows. A microscope slide glass plate comprising the porous semiconductor
layer 102 on which a 50 nm-titanium film had been deposited was immersed in a 40 mM
TiC14 aqueous solution at 70°C for 30 minutes, washed with water and ethanol, and dried with
N2 gas at high pressure. After the post-treatment, the surface of the porous semiconductor
layer 102 was covered with nanometer-sized Ti02 particles and exhibited a wider surface area.
The power conversion efficiency of the solar cell according to Example 10 was 7.2%, which
is considerably improved when compared to Example 8.

A dye-sensitized solar cell as illustrated in FIG. 16 was fabricated in the same manner
as in Example 3, except that an FTO glass was provided between the transparent substrate 10 1
and the porous Ti02 semiconductor layer 102 while using a transparent conductive electrode
503 instead of the first current collecting electrode 103. The power conversion efficiency
compared to that of Example 3 is shown in the following Table 3. Comparative Example 3
exhibited a 5.1 % efficiency.
[Table 3)
Power conversion
efficiency
7.2%
First current collecting electrode
Aluminum film having a
thickness of 50 nm deposited on
Exanlple 3
First
transparent
substrate
Slide glass
first sen~iconductorla yer
As can be seen in the result of Table 3, the dye-sensitized solar cell comprising the
Comparative
Example 3
current collecting electrode deposited on the porous semiconductor layer as in Example 3
exhibited much better efficiency than that of the dye-sensitized solar cell comprising the
Slide glass
current collecting electrode between the transparent substrate and the porous semiconductor
layer as in Comparative Example 3.
FTO deposited on glass
substrate
In the present invention, the most practical and preferred exemplary embodiments
5.1%
have been described, but the present invention should not be interpreted as being restricted to
the Examples and the drawings. In the present invention, various modifications may be
made within the spirit and scope described in the claims.
WE CLAIM:
[Claim 11
A dye-sensitized solar cell comprising:
a transparent substrate;
a porous semiconductor layer provided on the transparent substrate and comprising a
dye sensitizer;
a current collecting electrode provided on the porous semiconductor layer and
deposited such that a structure having at least one through-hole on the porous semiconductor
layer is formed;
a catalyst electrode; and
an electrolyte material provided between the transparent substrate and the catalyst
electrode.
[Claim 21
The dye-sensitized solar cell of claim 1, wherein the current collecting electrode has a
thickness from 5 nm to 1,000 nm, and a surface of the current collecting electrode has the
same topographical morphology as that of a surface of the porous semiconductor layer.
[Claim 31
The dye-sensitized solar cell of claim 1, further comprising:
a sealing spacer provided between the transparent substrate or the current collecting
electrode and the catalyst electrode.
[Claim 41
The dye-sensitized solar cell of claim 1, further comprising:
at least one internal spacer provided between the current collecting electrode and the
catalyst electrode.
(Claim 51
The dye-sensitized solar cell of claim 1, wherein the current collecting electrode
comprises titanium, nickel, platinum, gold, silver, copper, aluminum, tungsten, rhodium,
indium, tin oxide, fluorine-doped tin oxide (FTO), indium oxide, tin-doped indium oxide
(ITO), zinc oxide, carbon nanotubes, graphene, carbon black, PEDOT-PSS, polypyrrole,
polyaniline, poly-EDT, or a combination thereof.
[Claim 61
The dye-sensitized solar cell of claim 1, wherein the porous semiconductor layer
comprises titanium oxide, zinc oxide, tin oxide, niobium oxide, zirconium oxide, cerium
oxide, tungsten oxide, silicon oxide, aluminum oxide, nickel oxide, tantalum oxide, barium
titanate, strontium titanate, calcium titanate, zinc sulfide, lead sulfide, bismuth sulfide,
cadmium sulfide, CuA102, SrCu202, or a combination thereof.
[Claim 71
The dye-sensitized solar cell of claim 1, further comprising:
a pre-treatment layer formed between the transparent substrate and the porous
semiconductor layer by a semiconductor material pre-treatment.
[Claim 81
The dye-sensitized solar cell of claim 7, wherein the pre-treatment layer comprises
titanium oxide, zinc oxide, tin oxide, niobium oxide, zirconium oxide, cerium oxide, tungsten
oxide, silicon oxide, aluminum oxide, nickel oxide, tantalum oxide, barium titanate, strontium
titanate, calcium titanate, zinc sulfide, lead sulfide, bismuth sulfide, cadmium sulfide, CuA102,
SrCu202, or a combination thereof.
[Claim 91
The dye-sensitized solar cell of claim 1, further comprising:
a post-treatment layer formed on a surface of the porous semiconductor layer by a
semiconductor material post-treatment.
[Claim 101
The dye-sensitized solar cell of claim 9, wherein the post-treatment layer comprises
titanium oxide, zinc oxide, tin oxide, niobium oxide, zirconium oxide, cerium oxide, tungsten
oxide, silicon oxide, aluminum oxide, nickel oxide, tantalum oxide, barium titanate, strontium
titanate, calcium titanate, zinc sulfide, lead sulfide, bismuth sulfide, cadmium sulfide, CuA102,
SrCu202, or a combination thereof.
[Claim 111
The dye-sensitized solar cell of claim 1, wherein the porous semiconductor layer is
formed of particles having an average diameter from 1 nm to 400 nm.
[Claim 121
The dye-sensitized solar cell of claim 1, further comprising:
a transparent current collecting electrode provided between the transparent substrate
and the porous semiconductor layer.
[Claim 131
A dye-sensitized solar cell comprising:
a transparent substrate;
a first porous semiconductor layer provided on the transparent substrate and
comprising a first dye sensitizer;
a current collecting electrode provided on the first porous semiconductor layer;
a second porous semiconductor layer provided on the current collecting electrode and
comprising a second dye sensitizer;
a catalyst electrode; and
an electrolyte material provided between the transparent substrate and the catalyst
electrode.
(Claim 141
The dye-sensitized solar cell of claim 13, wherein the first dye sensitizer and the
second dye sensitizer are the same dye sensitizer.
[Claim 151
The dye-sensitized solar cell of claim 13, wherein the first dye sensitizer and the
second dye sensitizer absorb a wavelength range different from each other.
[Claim 161
The dye-sensitized solar cell of claim 13, further comprising:
a second current collecting electrode provided on the second porous semiconductor
layer.
[Claim 171
The dye-sensitized solar cell of claim 16, further comprising:
a third porous semiconductor layer provided on the second current collecting
electrode and comprising a third dye sensitizer.
[Claim 181
The dye-sensitized solar cell of claim 17, wherein the first dye sensitizer, the second
dye sensitizer, and the third dye sensitizer are the same dye sensitizer.
[Claim 191
The dye-sensitized solar cell of claim 17, wherein at least two dye sensitizers of the
first dye sensitizer, the second dye sensitizer, and the third dye sensitizer absorb a wavelength
range different from each other.
[Claim 201
The dye-sensitized solar cell of claim 17, further comprising:
a third current collecting electrode provided on the third porous semiconductor layer.
[Claim 211
The dye-sensitized solar cell of claim 13, further comprising:
a current collecting electrode provided between the transparent substrate and the first
porous semiconductor layer.
[Claim 221
A method for fabricating a dye-sensitized solar cell, the method comprising:
preparing a transparent substrate;
forming a porous semiconductor layer on the transparent substrate;
depositing a current collecting electrode on the porous semiconductor layer such that
a structure having at least one through-hole on the porous semiconductor layer is formed;
introducing a dye sensitizer into the porous semiconductor layer;
forming a catalyst electrode; and
introducing an electrolyte material between the transparent substrate and the catalyst
electrode.
[Claim 231
The method of claim 22, wherein the current collecting electrode has a thickness from
5 nm to 1,000 nm, and a surface of the current collecting electrode has the same topographical
morphology as that of a surface of the porous semiconductor layer.
[Claim 241
The method of claim 22, further comprising:
forming at least one internal spacer between the current collecting electrode and the
catalyst electrode.
[Claim 251
The method of claim 22, wherein the current collecting electrode comprises titanium,
nickel, platinum, gold, silver, copper, aluminum, tungsten, rhodium, indium, tin oxide,
fluorine-doped tin oxide (FTO), indium oxide, tin-doped indiun~ oxide (ITO), zinc oxide,
carboil nanotubes, graphene, carbon black, PEDOT-PSS, polypywolc, polyaniline, poly-EDT,
or a combination thereof.
[Claim 261
The method of claim 22, wherein the porous semiconductor layer comprises titanium
oxide, zinc oxide, tin oxide, niobium oxide, zirconium oxide, cerium oxide, tungsten oxide,
silicon oxide, aluminum oxide, nickel oxide, tantalum oxide, barium titanate, strontium
titanate, calcium titanate, zinc sulfide, lead sulfide, bismuth sulfide, cadmium sulfide, CuA102,
SrCu202, or a combination thereof.
[Claim 271
The method of claim 22, wherein the porous semiconductor layer is formed of
particles having an average diameter from 1 nm to 400 nm.
[Claim 281
The method of claim 22, further comprising:
forming an additional current collecting electrode between the transparent substrate
and the porous semiconductor layer.
[Claim 291
The method of claim 22, further comprising:
pre-treating the transparent substrate by a method selected from the group consisting
of a semiconductor layer material pre-treatment using a semiconductor material precursor
solution, a plasma treatment, an ozone treatment, and a chemical treatment.
[Claim 301
The method of claim 22, further comprising:
post-treating the transparent substrate by a method selected from the group consisting
of a semiconductor layer material post-treatment using a semiconductor material precursor
solution, a heat treatment, a plasma treatment, an ozone treatment, and a chemical treatment.
[Claim 3 11
A method for fabricating a dye-sensitized solar cell, the method comprising:
preparing a transparent substrate;
forming a first porous semiconductor layer on the transparent substrate;
depositing a first current collecting electrode on the first porous semiconductor layer;
introducing a dye sensitizer into the porous semiconductor layer;
forming a second porous semiconductor layer on the first current collecting electrode;
introducing a second dye sensitizer into the second porous semiconductor layer;
forming a catalyst electrode; and
introducing an electrolyte material between the transparent substrate and the catalyst
electrode.
[Claim 321
The method of claim 3 1, further comprising:
depositing a second current collecting electrode on the second porous semiconductor
layer.
[Claim 331
The method of claim 32, further comprising:
forming a third porous semiconductor layer on the second current collecting
electrode; and
introducing a third dye sensitizer into the third porous semiconductor layer.
[Claim 341
The method of claim 3 1, further comprising:
forming an additional current collecting electrode between the transparent substrate
and the first porous semiconductor layer.
[Claim 351
The method of claim 3 1, further comprising:
pre-treating the transparent substrate by a method selected from the group consisting
of a semiconductor layer material pre-treatment using a semiconductor material precursor
solution, a plasma treatment, an ozone treatment, and a chemical treatment.
[Claim 361
The method of claim 3 1, ft~rtherc omprising:
post-treating the transparent substrate by a method selected from the group consisting
of a semiconductor layer material post-treatment using a semiconductor material precursor
solution, a heat treatment, a plasma treatment, an ozone treatment, and a chemical treatment.