KR102046295B1 - Dye-Sensitized Solar Cell Having Light Scattering Layer of Porous Particle - Google Patents

Abstract

The present invention is a first electrode; A second electrode disposed to face the first electrode; A light absorption layer formed of a semiconductor oxide or a metal oxide deposited on the first electrode and having a dye adsorbed on a surface thereof; A light scattering layer stacked on the light absorbing layer and having porous nanoparticles; And it relates to a dye-sensitized solar cell comprising an electrolyte containing an oxidation-reduction ion pair is filled between the first electrode and the light scattering layer. By applying the porous nanoparticles to the light scattering layer, the electrolyte can be quickly moved to the dye of the light absorbing layer, it is possible to improve the light scattering effect.

Description

Dye-Sensitized Solar Cell Having Light Scattering Layer of Porous Particle

The present invention relates to a dye-sensitized solar cell, and more particularly to a dye-sensitized solar cell having a structure capable of improving the movement of the electrolyte.

Recently, the demand for new energy development and commercialization is increasing due to environmental problems caused by soaring oil prices and greenhouse gas emissions. Among future energy technologies called renewable energy, there is a growing interest in environmentally friendly solar cells that use solar light as an energy source.

In general, a solar cell refers to a device that converts light energy into electrical energy using a photoelectric effect generated by sunlight. Here, the photoelectric effect is that electrons in a material are excited by light energy, electron-hole pairs are generated, and electrons and holes are moved in opposite directions by an internal electric field, thereby generating photovoltaic power. It means the phenomenon.

Solar cells are silicon based solar cells, CdTe (cadmium Telluride, cadmium- telluride) solar cells, CIGS / CIS (Copper-Indium-Gallium-Selenide, copper) -Indium-gallium-selenium / copper-indium-selenide, copper-indium-selenium) solar cells and the like.

The first silicon-based solar cell developed has an advantage that it can be easily obtained by forming a photoelectric layer with amorphous silicon. However, silicon-based solar cells are not economically feasible due to expensive manufacturing equipment, rising prices of silicon raw materials, and limited installation sites. CIGS / CIS solar cells contain indium in the photovoltaic area, whose price has soared due to the recent shortage of supply, resulting in reduced production costs. CdTe solar cells are rare raw materials and contain cadmium, which can cause pollution, so mass production is not easy and there are environmental problems.

Dye-sensitized solar cells (DSSC) have been developed to solve the problems of such silicon-based solar cells. After the dye-sensitized solar cell was developed in 1991 by Michael Gratzel of the Swiss National Lausanne Institute of Advanced Technology (EPFL) using nanoparticle titanium oxide (TiO ₂ ) with an anatase structure, Much research and development is in progress. Dye-sensitized solar cells have a lower manufacturing cost and superior energy conversion efficiency than silicon solar cells having a conventional pn junction structure.

Dye-sensitized solar cells use an oxide semiconductor electrode composed of a photosensitive dye capable of absorbing light in the visible wavelength range and generating electron-hole pairs, and nanocrystalline particles for transferring the generated electrons. It is a photoelectric conversion element to be used.

To achieve this function, dye-sensitized solar cells are arranged oppositely facing the conductive surface of the semiconductor electrode and the opposite electrode. At this time, a light absorbing layer made of titanium oxide to which dye molecules are adsorbed is formed on the upper surface of the semiconductor electrode. Meanwhile, an electrolyte solution is injected between the semiconductor electrode and the opposite electrode to supply electrons to the dye molecules adsorbed on the surface of the titanium oxide forming the light absorption layer through an oxidation-reduction reaction.

Therefore, when light is irradiated, dye molecules adsorbed on the surface of the light absorbing layer may form electron-hole pairs. In this case, electrons are injected into the conduction band of the titanium oxide particles of the light absorbing layer, and are transferred to the semiconductor electrode through the interface between the nanoparticles to generate a current. On the other hand, the holes generated by the dye molecules are reduced by receiving electrons by the electrolyte solution to operate the dye-sensitized solar cell.

Recently, a dye-sensitized solar cell having a double layer structure of a light absorbing layer-light scattering layer is formed by forming a light scattering layer composed of nanoparticles such as titanium oxide in the light absorbing layer to improve light absorption into the light absorbing layer. Is widely used.

However, in general, the average particle diameter of the titanium oxide used in the light absorbing layer is 10 to 30 nm, while the average particle diameter of the titanium oxide constituting the light scattering layer formed between the light absorbing layer and the electrolyte solution is in the absorption wavelength band of the dye. In order to have sufficient scattering characteristics in consideration of the light source blocking power of the should have an average particle diameter of 250 nm or more, for example 300 to 500 nm.

As the size of the particles increases, the volume of the pores decreases, that is, the porosity is inversely proportional to the size of the particles, so that the electrolyte solution does not properly pass through the light scattering layer having a particle diameter approximately 20 times larger than that of the light absorbing layer. In other words, the movement path of the electrolyte is limited by the light scattering layer having a relatively large particle diameter, so that the electrolyte solution does not efficiently transfer electrons to the dye molecules adsorbed on the surface of the light absorbing layer.

The present invention has been proposed to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide a dye-sensitized solar cell configured to allow the electrolyte to efficiently move to the light absorbing layer.

The present invention having the above object is a first electrode; A second electrode disposed to face the first electrode; A light absorbing layer deposited on the first electrode and having nanoparticles made of a semiconductor oxide or a metal oxide having a dye adsorbed on a surface thereof; A light scattering layer stacked on the light absorbing layer and having porous nanoparticles; And it provides a dye-sensitized solar cell comprising an electrolyte containing an oxidation-reduction ion pair is filled between the second electrode and the light scattering layer.

The average particle diameter of the porous nanoparticles is 300 to 500 nm, the porous nanoparticles are characterized in that the fine nanoparticles having an average particle diameter of 10 to 20 nm formed by agglomeration.

Preferably, the porous nanoparticles may be titanium oxide (TiO ₂ ) nanoparticles.

On the other hand, the semiconductor oxide or the metal oxide forming the light absorption layer is titanium (Ti) oxide, zirconium (Zr) oxide, strontium (Sr) oxide, zinc (Zn) oxide, indium (In) oxide, lanthanum (La) Oxide, vanadium (V) oxide, molybdenum (Mo) oxide, tungsten (W) oxide, tin (Sn) oxide, niobium (Nb) oxide, magnesium (Mg) oxide, aluminum (Al) oxide, yttrium (Y ), Scandium (Sc) oxide, samarium (Sm) oxide, gallium (Ga) oxide, strontium titanium (SrTi) oxide, and calcium titanate (CaTiO ₃ ) may include a material selected from at least one. have.

For example, the nanoparticles of the light absorbing layer have an average particle diameter of 10 to 20 nm.

Preferably, the nanoparticles of the light absorption layer is characterized in that deposited on top of the first electrode to a thickness of 5 ~ 20 ㎛.

Meanwhile, according to an exemplary embodiment of the present invention, the first electrode may include a first substrate made of transparent glass or transparent plastic material; And a first transparent electrode formed on the first substrate and made of a material selected from the group consisting of fluorine-doped tin oxide (FTO), tin-doped indium oxide (ITO), and zinc oxide. Can be.

The second electrode may include a second substrate made of transparent glass or transparent plastic; A second transparent electrode formed on the second substrate and made of a material selected from the group consisting of fluorine-doped tin oxide (FTO), tin-doped indium oxide (ITO), and zinc oxide; And ruthenium, osmium, cobalt, rhodium, iridium, nickel, activated carbon, carbon nanotube (CNT), graphene, palladium, platinum, poly (3,4-ethylenedioxythiophene) (PEDOT) It may include a catalyst layer formed of a material selected from the group consisting of, polythiophene and polyaniline.

Dyes that can be adsorbed onto the surface of the nanoparticles of the light absorbing layer are photosensitive dyes, and include, for example, ruthenium dyes, xanthene dyes, cyanine dyes, porphyrin dyes, and anthraquinone dyes.

In addition, the electrolyte is characterized in that the halogen-based redox electrolyte.

In the dye-sensitized solar cell of the present invention, a porous structure is adopted in the light scattering layer having a larger size than that of the light absorbing layer, so that the electrolyte solution moves rapidly through a plurality of pores formed in the light scattering layer, thereby causing dye molecules in the light absorbing layer. It can efficiently transfer electrons to the surface.

1 is a cross-sectional view schematically showing a laminated structure of a dye-sensitized solar cell according to an exemplary embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view of region A of FIG. 1 and schematically illustrates the movement of an electrolyte to a light absorbing layer to which dye is adsorbed through a light scattering layer of porous particles. The left side is a state in which the movement of the electrolyte is disturbed by the light absorbing layer having no conventional pore structure, and thus the electrolyte is not properly moved to the dye molecules, and the right side is the electrolyte through the pores of the light scattering layer composed of porous particles according to the present invention. It is in a state of rapidly moving to the dye molecule.
Figure 3 is a SEM image of the particles used in the light scattering layer of the conventional dye-sensitized solar cell.
4A and 4B are SEM images of the porous particles used in the light scattering layer of the dye-sensitized solar cell according to the present invention, respectively, FIG. 4A is a 15,000 times magnification and FIG. 4B is a 150,000 times magnification.
Figure 5 is a graph measuring the transmittance according to the optical wavelength band of the solar cell to which the light scattering layer of porous particles according to the present invention.

The present inventors have completed the present invention by focusing on the fact that the electrolyte can move quickly and efficiently to the light absorbing layer by adopting particles having a porous structure in the light scattering layer. Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 is a cross-sectional view schematically showing a laminated structure of a dye-sensitized solar cell according to an exemplary embodiment of the present invention, Figure 2 is an enlarged cross-sectional view of the region A of Figure 1, a dye through a light scattering layer of porous particles Is a diagram schematically showing the movement of the electrolyte to the adsorbed light absorbing layer.

As shown in FIG. 1, the dye-sensitized solar cell 100 according to the exemplary embodiment of the present invention is disposed in a form in which the first electrode 200 and the second electrode 300 are spaced apart from each other. The light absorbing layer 230 and the light scattering layer 240 are sequentially stacked and formed on the first electrode 200 as a photoelectric region between the first electrode 200 and the second electrode 300. An electrolyte 400 is injected and filled between the 200 and the light scattering layer 240.

The first electrode 200, also called a semiconductor electrode or photoelectrode, functions as an anode. For example, the first electrode 200 is formed on the first substrate 210 made of transparent glass or transparent plastic and the first substrate 210 to apply electrons excited by light energy to an external load. It may include a first transparent electrode 220. In this case, the first transparent electrode 220 has good light transmittance so that sunlight can transmit well, and has conductivity so that electrons excited by light energy can be applied, and the semiconductor particles or the metal formed in the light absorbing layer 230. The oxide particles may be easily adhered to each other, may have a sufficiently low resistance to minimize the loss of electrons, and may be formed of a material capable of preventing oxidation by the electrolyte introduced from the electrolyte 400. For example, the first transparent electrode 220 is selected from the group consisting of fluorine-doped tin oxide (F-doped SnO 2, FTO), tin-doped indium oxide (ITO), and zinc oxide (ZnO). Either substance.

The second electrode 300 is called a counter electrode or a catalyst electrode and functions as a cathode. For example, the second electrode 300 is a second substrate 310 made of transparent glass or transparent plastic and a second substrate 310 formed on the second substrate 310 to receive electrons from an external load and apply them to the photoelectric region. 2 may include a transparent electrode 320. In this case, the second transparent electrode 220 should have a role of a catalyst capable of reducing the electrolyte and an energy potential capable of functioning as a battery, and has a resistance low enough to minimize the loss of electrons. It may be formed of a material that can be prevented from oxidation by the electrolyte introduced from the). For example, the second transparent electrode 320 is any selected from the group consisting of fluorine-doped tin oxide (F-doped SnO 2, FTO), tin-doped indium oxide (ITO), and zinc oxide (ZnO). It is a substance.

In addition, one surface of the second transparent electrode 320 is formed of a catalyst layer 330 composed of an oxidation-reduction catalyst including a material having strong acid resistance to prevent corrosion due to electrolyte. For example, the medium for forming the catalyst layer 330 may be ruthenium, osmium, cobalt, rhodium, iridium, nickel, activated carbon, carbon nanotube (CNT), graphene, palladium, platinum, or poly It may be composed of a conductive polymer such as (3,4-ethylenedioxythiophene) (PEDOT), polythiophene, and polyaniline, and is preferably platinum having good light absorption efficiency.

In particular, the catalyst layer 330 preferably has a high light transmittance so as to allow light reception through the catalyst layer 330. In the case of using a material having high light transmittance as the catalyst layer 330, even when sunlight is incident through the catalyst layer 330, the electrolyte 400 emits ultraviolet rays (UV) before the sunlight reaches the first electrode 200. Since the absorption may be prevented, deterioration or decomposition of the dye 234 adsorbed to the light absorbing layer 230 stacked on the first electrode 200 may be prevented to ensure long-term stability of the battery.

In this case, in the drawing, the first electrode 200 is divided into the first substrate 210 and the first transparent electrode 220, and the second electrode 300 is the second substrate 310 and the second transparent electrode 320. However, when the first substrate 210 and the second substrate 310 are made of a conductive material, the first transparent electrode 220 and the second transparent electrode 320 may be omitted.

On the other hand, between the first substrate 200 and the second substrate 300 substantially corresponds to a photoelectric region for converting light energy into electrical energy. For example, the photoelectric region includes a light absorbing layer 230 deposited and formed on the first transparent electrode 220; A light scattering layer 240 stacked on the light absorbing layer 230; And an electrolyte 400 that is injected and formed between the catalyst layer 330 and the light scattering layer 240.

The light absorbing layer 230 includes nanoparticles 232 composed of nano-sized semiconductor oxides or metal oxides having a wide band gap serving as n-type semiconductors as a whole, and dyes 234 adsorbed onto the surfaces of the nanoparticles 232. It includes. The nanoparticle 232 is an n-type semiconductor oxide or a metal oxide, and provides a path for the excited electrons to move to the first transparent electrode 220. For example, the nanoparticles 232 in the light absorption layer 230 may apply a paste including metal oxide or semiconductor oxide particles on the first transparent electrode 220 or may be formed by screen printing.

The nanoparticles 232 constituting the light absorbing layer 230 may be, for example, nanotube shape or nanorod shape, and may have a porous nanoparticle shape if necessary. To produce nanotube-shaped or nanorod-shaped nanoparticles 232, spherical nanoparticles of semiconductor oxides or metal oxides are treated in strong alkali to grow into nanotubes, or nanorods inside a micelle of a surfactant. The same method as for growing can be used.

In addition, the nanoparticles 232 in the light absorbing layer 230 may be deposited on the first transparent substrate 220 to a thickness of 5 ~ 20㎛. In the case of depositing the nanoparticles 232 to such a thickness, it is possible to provide a path of electron transfer in which the photocurrent is maximized, and the specific surface area is maximized so that the dye may be easily adsorbed.

For example, the semiconductor oxide or metal oxide constituting the nanoparticles 232 may be titanium (Ti) oxide, zirconium (Zr) oxide, strontium (Sr) oxide, zinc (Zn) oxide, indium (In) oxide, or lanthanum (La). Oxide, vanadium (V) oxide, molybdenum (Mo) oxide, tungsten (W) oxide, tin (Sn) oxide, niobium (Nb) oxide, magnesium (Mg) oxide, aluminum (Al) oxide, yttrium ( Y) oxide, scandium (Sc) oxide, samarium (Sm) oxide, gallium (Ga) oxide, strontium titanium (SrTi) oxide, and calcium titanate (CaTiO ₃ ) is selected from the group consisting of at least one material. Preferably, the titanium oxide has a good bandgap energy, good conductivity, and long retention time of electrons, and more preferably, an anatase type titanium oxide.

At this time, the average particle diameter of the nanoparticles 232 is preferably 10 ~ 20 nm. If the average particle diameter of the nanoparticles 232 is less than 10 nm, the amount of adsorption of the dye 234 to the nanoparticles 232 increases, but the number of surface states increases so that there is an opportunity for the excited electrons to re-bond to the holes. Can increase. On the other hand, if the average particle diameter of the nanoparticles 232 exceeds 20 nm, the amount of adsorption of the dye 234 to the nanoparticles 232 may be reduced, thereby reducing the number of electrons that can be excited. Therefore, if the average particle diameter of the nanoparticles 232 is out of the above-described range, the photoelectric conversion efficiency may be reduced.

In addition, the dye 234 coated in a single layer structure is adsorbed on the surface of the nanoparticles 232. The dye 234 is a photosensitive dye material capable of generating excited electrons in response to the irradiated light. The dye 234 may be firmly combined with the nanoparticles 232 and may be formed of a thermally and optically stable material.

For example, the dye may include xanthene dyes, cyanine dyes, porphyrin dyes, anthraquinone dyes, in addition to ruthenium dyes such as ruthenium complexes such as ruthenium 535 dye, ruthenium 535 bis-TBA dye, and ruthenium 620-1H3TBA dye. Can be used.

Conventional methods may be used to adsorb the dye 234 to the nanoparticles 232 in the form of semiconductor oxides or metal oxides, but preferably the dye 234 may be alcohol, nitrile, halogenated hydrocarbons, ethers, amides, After dissolving in a solvent such as ester, ketone or N-methylpyrrolidone, a method of dipping the first electrode 200 to which the nanoparticles 232 are applied may be used.

Meanwhile, the light scattering layer 240 stacked on the light absorbing layer 230 includes porous nanoparticles 242 having an average particle diameter of about 20 to 30 times larger than the nanoparticles 232 constituting the light absorbing layer 230. Have The light scattering layer 240 increases the light path by scattering external light transmitted through the first electrode 200 and incident on the photoelectric region, and reflects external light toward the light absorbing layer 230.

For example, the porous nanoparticles 242 are dispersed in a suitable solvent, a solution in which the porous nanoparticles 242 are dispersed is coated or screen printed on the light absorbing layer 230, and then dispersed through a heat treatment process or a drying process. The light scattering layer 240 may be stacked on the light absorbing layer 230 by a method of removing the solvent.

In particular, a plurality of pores 244 are formed in the porous nanoparticles 242 constituting the light scattering layer 240 according to the present invention, and the average particle diameter of the porous nanoparticles 242 is approximately 300 to 500 nm. Preferably, it is 380-450 nm. The porous nanoparticles 242 may be made of, for example, titanium oxide (TiO ₂ ).

The porous nanoparticles 242 will be described in more detail with reference to FIG. 2. As shown in FIG. 2, the porous nanoparticles 242 constituting the light scattering layer 240 according to the present invention aggregate a plurality of fine nanoparticles 246 having a particle diameter of about 10 to 20 nm therein. It has a structure that is aggregated. That is, according to the present invention, the porous nanoparticles 242 constituting the light scattering layer 240 have a gap formed between the plurality of fine nanoparticles 246 aggregated therein, and the plurality of pores 244. It is a porous material that forms. Methods of preparing such porous nanoparticles are well known, for example, hydrothermal synthesis using high temperature and high pressure reaction in a colloidal state by adding a precursor to a solvent, but porous nanoparticles can be synthesized using other methods. have.

Porous nanoparticles 242 according to the present invention is a form in which a plurality of fine nanoparticles 246 are aggregated therein. As described above, since the porosity of the particles is generally inversely proportional to the size of the particles, the fine nanoparticles 246 having an average particle diameter of 10 to 20 nm, as in the present invention, have an average particle diameter of 300 to 500 nm. Compared to the nanoparticles (shown on the left side of FIG. 2) in the conventional light scattering layer 240, the porosity is relatively large. Therefore, the plurality of fine nanoparticles 246 may have a plurality of pores.

Accordingly, as shown in the right side of FIG. 2, the electrolyte absorbs the light absorbing layer 230 through the plurality of pores 244, which are gaps between the plurality of fine nanoparticles 246 formed inside the porous nanoparticles 242. It is possible to move quickly to the dye molecule 234 in the middle. In other words, according to the present invention, the electrolyte may quickly move to the dye molecules 234 through the plurality of pores 244 formed in the porous nanomaterial 242 constituting the light scattering layer 240. Accordingly, holes generated in the dye molecules 234 may be rapidly supplied with electrons from the electrolyte 400, and thus may be efficiently reduced. In particular, in the case of adopting hollow particles, the scattering area of the hollow particles scatters light in a long long wavelength band as compared with the absorption wavelength band of the dye 234, whereas scattering efficiency may be lowered. The porous nanoparticles 242 in which the plurality of fine nanoparticles 246 are aggregated do not reduce scattering efficiency.

On the other hand, as shown on the left side of FIG. 2, since the particles constituting the light scattering layer in the conventional solar cell structure have a relatively large particle diameter and small porosity, the electrolyte is difficult to pass through these particles. Pass or very slowly. Therefore, since the holes formed in the dye molecules 234 are not rapidly supplied with electrons from the electrolyte 400, the reduction rate is lowered, which may cause a problem in overall photoelectric conversion efficiency.

Meanwhile, the dye-sensitized solar cell 100 of the present invention is filled with, for example, an electrolyte 400 in which a liquid electrolyte is injected between the second electrode 200 and the light scattering layer 240 described above. The electrolyte 400 serves as a p-type semiconductor, and includes an oxidation-reduction pair. For example, the electrolyte consists of an iodine-based redox pair comprising a medium, and the medium may be applied with a liquid such as acetonitrile or a polymer such as polyvinylidene fluoride (PVDF). As such, since the electrolyte 400 includes an oxidation-reduction pair, the electrolyte 400 may react with electrons applied from an external load through the second electrode 300 to cause an oxidation-reduction reaction.

For example, the electrolyte that can be used as the electrolyte 400 of the dye-sensitized solar cell 100 of the present invention may be composed of a solvent-based liquid electrolyte, a polymer electrolyte, a solid electrolyte and a gel electrolyte. When a solvent-based liquid electrolyte is used, it is preferably a halogen-based redox electrolyte, more preferably an iodine-based redox electrolyte.

For example, the halogen-based redox electrolyte that can be used as an oxidation / reduction pair of the electrolyte 400 may be composed of halogen compounds / halogen molecules. To an available halogen molecule, for example, and the like molecular iodine (I ₂₎ or bromine molecule (Br _2), especially preferred it is iodine. These halogen molecules are, for example, acetonitrile, propionitrile, methoxy acetonitrile, propylene carbonate, and mixtures thereof, which are non-protonic solvents. is dissolved in ion state exists as (I ₂ ^{- -} or Br _2).

On the other hand, halogen compounds having counter ions (relative ions) of halogen ions include halogenated metal salts (halogenated metal compounds) or halogenated organic salts (halogenated organic compounds). For example, LiI, NaI, KI, Tetra-alkyl ammonium iodide (R ₄ NI), 0.1 to 0.5 molarity (M) of imidazolium derivative iodides and A mixture of the same iodides can be used as the halogen compound. The cell performance of a dye-sensitized solar cell has a different ion conductivity in the electrolyte, or shift of the conduction band level of the nanoparticles 232 by the dye 234 adsorbed on the surface of the nanoparticles 232 of the light absorbing layer 230. It depends on the counter cations of iodine compounds such as Li ⁺ , Na ⁺ , K ⁺ , and R ₄ N ⁺ , which are counter ions that lead to The viscosity of the solvent directly affects the ionic conductivity of the electrolyte, with low viscosity solvents being preferred.

When the above-described oxidation / reduction pair is dissolved in a solvent and used, the oxidation / reduction pair may be used in any concentration with respect to the solvent. For example, the halogen compound may have a concentration of 0.05-5 M with respect to the solvent, preferably 0.2-1. M concentration, the halogen molecule may be used at a concentration of 0.0005 to 1 M, preferably 0.001 to 0.1 M with respect to the solvent.

Although not shown, two injection holes are provided to penetrate a part of the second electrode 300 so as to inject a liquid electrolyte into the sealed photoelectric region. In order to prevent the electrolyte from leaking to the outside, two injection holes are each sealed with a sealing material.

In addition, the nanoparticles 232 and the porous nanoparticles 242 coated with the injected electrolyte 400 and the dye 234 may be prevented from leaking to the outside, blocking the penetration of moisture and oxygen from the outside, and the first substrate. A spacer (adhesive pattern 410) as an adhesive is provided along the edges of the first and second substrates 200 and 300 so that the 200 and the second substrate 300 can be bonded together to maintain the panel state. .

The spacer 410 is made of a transparent polymer material to allow sunlight to pass through. For example, polyvinyl chloride (PVC), polyamide (PA), polyimide (PI), polyethylene (P), and polyethylene terephthalate ( PET), polyethylene naphthalate (PEN), polycarbonate (PC), thermoplastic polyurethane (TPU), ethylene vinyl acetate (EVA), cellulose and combinations thereof. For example, the spacer 410 may be formed of Sullyn (Surlyn, DuPont) in the form of a film.

The driving of the dye-sensitized solar cell 100 according to the present invention having the above-described configuration will be briefly described. When sunlight is incident on the dye-sensitized solar cell 100 according to the present invention, the photons transmitted through the transparent first substrate 210 and the first transparent electrode 220 constitute nanoparticles 232 constituting the light absorbing layer 230. ) Is absorbed by the dye 234 coated on the surface. The dye 234, which absorbs light energy above its low bandgap energy, is in an excited state to generate electrons, and the generated electrons are semiconductor oxides or metal oxides forming the nanoparticles 232. It is moved to the first electrode 200 via the transfer to the conducting band of and is applied to the second electrode 300 side by a closed circuit. The electrons applied to the second electrode 300 oxidize the electrolyte 400 to generate electrons, and the generated electrons form a plurality of pores 244 formed in the porous nanoparticles 242 of the light scattering layer 240. It quickly engages with the holes of the dye 234 while moving to the dye 234 side.

Hereinafter, the present invention will be described through exemplary embodiments, but the present invention is not limited thereto.

Synthesis Example: Synthesis of Porous Titanium Oxide Particles for Light Scattering Layer

Porous titanium oxide particles were synthesized through the following procedure. After dropping 2 mL of tetrabutyl titanate in 100 mL of acetic acid, the solution was stirred to prepare a colloidal solution. The colloidal solution prepared was transferred to a Ti autoclave vessel to prepare a high temperature and high pressure reaction. TiO ₂ particles were grown by reaction soaking at 200 ° C. for 24 hours. The TiO ₂ particles dispersed in acetic acid were washed with ethanol (EtOH) and centrifuged three times. After washing, redispersed in ethanol using a sonic horn, the content of dispersed TiO ₂ particles was calculated, and Binder was added at a fixed ratio relative to the solids. The TiO ₂ dispersed in ethanol and the binder were mixed in a vacuum evaporator to remove ethanol as a dispersion solvent, and the final product was subjected to a 3-roll mill for 30 minutes.

Example: Fabrication of Dye-Sensitized Solar Cell

(1) Fabrication of semiconductor electrode (first electrode)

Cut FTO glass (Fluorine-doped tin oxide coated conduction glass, Pilkington, TEC7) into a size of 10 cm X 10 cm and perform a sonication cleaning with a glass cleaner for 10 minutes and then completely remove the soapy water using distilled water. It was. Thereafter, the sonication washing with ethanol was repeated twice for 15 minutes, rinsed thoroughly with anhydrous ethanol, and dried in an oven at 100 ° C. In order to improve the contact force with TiO ₂ on the thus prepared FTO glass, it was immersed in 40 mM Titanium (IV) chloride solution at 70 ° C. for 40 minutes, washed with distilled water, and then thoroughly dried in an oven at 100 ° C. After that, CCIC titanium dioxide (TiO ₂ ) paste (18-NR) was coated on a FTO glass using a screen printer (200 mesh) having a size of 9 mm X 9 mm. The process of drying the coated film in an oven at 100 ° C. for 20 minutes was repeated three times. By firing at 450 ° C. for 60 minutes, a TiO ₂ film having a thickness of about 10 micrometers was obtained.

The silver paste was coated on the photoelectrode after the heat treatment in a predetermined pattern, dried in an oven at 100 ° C. for 20 minutes, and baked at 450 ° C. for 30 minutes to form an electron collecting electrode having a light absorbing layer laminated thereon. The glass frit paste was applied in a predetermined pattern on the electron collecting electrode, dried in an oven at 100 ° C. for 20 minutes, and then baked at 480 ° C. for 20 minutes to form a glass frit protective layer. The dye can be adsorbed by immersing the TiO ₂ film in anhydrous ethanol solution of the synthesized dye at 0.5 mM concentration for 24 hours (if the dye is not dissolved in anhydrous ethanol, use a solvent that can dissolve). After the adsorption was completed, the dye that was not adsorbed with anhydrous ethanol was completely washed and dried using a heat gun. Subsequently, the porous titanium oxide nanoparticles prepared in the above synthesis example dispersed in a solvent were dropped onto the light absorbing layer where the dye on the electron collecting electrode was adsorbed after ultrasonic cleaning to form a light scattering layer. The photoelectrode on which the light scattering layer was formed was dried in an oven at 100 ° C., and calcined at 450 ° C. to form a light scattering layer from which both the dispersion solvent and the binder were removed.

(2) Preparation of counter electrode (second electrode)

Two holes for electrolyte injection were formed using a 0.7 mm diameter diamond drill (Dremel multipro395) in a 10 cm × 10 cm FTO glass. After that, it was washed and dried in the same manner as the cleaning method proposed in the photoelectrode. Thereafter, hydrogen hexachloroplatinate (H 2 PtCl 6) 2-propanol solution was applied to the FTO glass, and then calcined at 450 ° C. for 60 minutes. The silver paste was applied in a predetermined pattern on the finished catalyst electrode, dried for 20 minutes in an oven at 100 ° C., and calcined at 450 ° C. for 30 minutes to form a catalyst electrode. The glass frit paste was applied on the electrode in a predetermined pattern, dried in an oven at 100 ° C. for 20 minutes, and then baked at 480 ° C. for 20 minutes to form a glass frit protective layer.

(3) Sandwich cell manufacturing

Surlyn (Solaronix, SX1170-25 Hot Melt) cut into rectangular bands was placed between the photoelectrode and the counter electrode, and the two electrodes were attached to each other using a hot-press. Subsequently, an electrolyte was injected through two small holes formed in the counter electrode, and a sandwich cell was manufactured by sealing with Surlyn strip (DuPont) and cover glass. As an electrolyte solution, 0.1M LiI, 0.05M I2, 0.6M 1-hexyl-2,3-dimethylimidazolium iodide and 0.5M 4-tert-butylpyridine were prepared with 3-metoxypropionitrile solvent.

Comparative Example: Fabrication of Solar Cell Applying Conventional Light Scattering Layer Particles

A dye-sensitized solar cell was fabricated by repeating the procedure of Example, except that the light scattering layer particles were not formed of pores and the light scattering layer was formed using titanium oxide particles (CCIC) having an average particle diameter of 300 to 500 nm. It was.

Experimental Example 1 Observation of Light Scattering Layer Particles

The nano-sized titanium oxide particles synthesized in the synthesis example and the nano-sized titanium dioxide particles, the conventional light scattering layer particles used in the comparative example, were observed using SEM. Figure 3 is a SEM image of the conventional light scattering layer particles, Figure 4a and Figure 4b is a SEM image of the light scattering layer particles of nano-sized titanium dioxide synthesized in the synthesis example.

As shown in FIG. 3, particles of the light scattering layer of the prior art are formed with particles of several hundred nm, and no pores are formed inside these particles. On the other hand, as shown in Figures 4a and 4b, the nano-sized titanium oxide particles synthesized in the synthesis example has an approximately elliptical structure and the particle diameter is approximately 300 ~ 500 nm. In addition, it can be seen that internal particles having a particle diameter of approximately 10 to 20 nm are aggregated inside the entire nano-sized titanium oxide particles, and have a plurality of pores therebetween.

Experimental Example 2: Light transmittance and fill-factor measurement

The light transmittance was measured according to a standard method using the solar cells prepared in each of the Examples and Comparative Examples. The result is shown in FIG. In particular, the solar cell applying the light scattering layer to the nanoparticles formed with a plurality of pores according to the present invention is known to reflect all the incident light in the wavelength band of 360 nm or more, which is the wavelength band used by the solar cell by scattering. Could. On the other hand, the fill-factor (FF) of the solar cells manufactured in Examples and Comparative Examples were measured. According to the present invention, the FF of the solar cell to which the light scattering layer of the porous particles is applied is 66.1%, which is improved compared to the FF 65.3% of the solar cell manufactured according to the comparative example.

Although the present invention has been described above based on the embodiments of the present invention, the present invention is not limited to the above-described embodiments. Rather, those skilled in the art will be able to devise various modifications and changes based on the embodiments described above. However, all such modifications and variations are to be construed as being included in the scope of the present invention, and will be more apparent through the appended claims.

100 dye-sensitized solar cell 200 first electrode
210: first substrate 220: first transparent electrode
230: light absorbing layer 232: nanoparticles
234: dye 240: light scattering layer
242: porous nanoparticles 244: pores
246: fine nanoparticles 300: second electrode
310: second substrate 320: second transparent electrode
330: catalyst layer 400: electrolyte

Claims (11)

A first electrode;
A second electrode disposed to face the first electrode;
A light absorbing layer deposited on the first electrode and having nanoparticles made of a semiconductor oxide or a metal oxide on which a dye is adsorbed on a surface thereof, the nanoparticles having an average particle diameter of 10 to 20 nm;
A light scattering layer laminated on the light absorbing layer and having porous nanoparticles, the average particle diameter of the porous nanoparticles is 300 to 500 nm, and the porous nanoparticles have fine nanoparticles having an average particle diameter of 10 to 20 nm. A light scattering layer formed by agglomeration in the porous nanoparticles; And
Electrolyte containing a redox ion pair is filled between the second electrode and the light scattering layer
Dye-sensitized solar cell comprising a.
The method of claim 1,
An average particle diameter of the porous nanoparticles is 380 ~ 450 nm dye-sensitized solar cell.
The dye-sensitized solar cell of claim 1 or 2, wherein the porous nanoparticles are titanium oxide (TiO ₂ ) nanoparticles.
The method according to claim 1 or 2,
The semiconductor oxide or the metal oxide may be titanium (Ti) oxide, zirconium (Zr) oxide, strontium (Sr) oxide, zinc (Zn) oxide, indium (In) oxide, lanthanum (La) oxide, vanadium (V) oxide, Molybdenum (Mo) oxide, tungsten (W) oxide, tin (Sn) oxide, niobium (Nb) oxide, magnesium (Mg) oxide, aluminum (Al) oxide, yttrium (Y) oxide, scandium (Sc) oxide Dye-sensitized solar cell comprising a material selected from the group consisting of, samarium (Sm) oxide, gallium (Ga) oxide, strontium titanium (SrTi) oxide, and calcium titanate (CaTiO ₃ ).
delete The method according to claim 1 or 2,
The nanoparticles of the light absorption layer is a dye-sensitized solar cell, characterized in that deposited on top of the first electrode with a thickness of 5 ~ 20 ㎛.
The method according to claim 1 or 2,
The first electrode may include a first substrate made of transparent glass or transparent plastic; And a first transparent electrode formed on the first substrate and made of a material selected from the group consisting of fluorine-doped tin oxide (FTO), tin-doped indium oxide (ITO), and zinc oxide. Dye-Sensitized Solar Cell.
The method according to claim 1 or 2,
The second electrode may include a second substrate made of transparent glass or transparent plastic; A second transparent electrode formed on the second substrate and made of a material selected from the group consisting of fluorine-doped tin oxide (FTO), tin-doped indium oxide (ITO), and zinc oxide; And ruthenium, osmium, cobalt, rhodium, iridium, nickel, activated carbon, carbon nanotube (CNT), graphene, palladium, platinum, poly (3,4-ethylenedioxythiophene) (PEDOT) Dye-sensitized solar cell comprising a catalyst layer formed of a material selected from the group consisting of polythiophene and polyaniline.
The method according to claim 1 or 2,
The dye is a dye-sensitized solar cell comprising a ruthenium dye, xanthene dye, cyanine dye, porphyrin dye and anthraquinone dye.
The method according to claim 1 or 2,
The electrolyte is a dye-sensitized solar cell, characterized in that the halogen-based redox electrolyte. The method according to claim 1 or 2,
The fine nanoparticles are dye-sensitized solar cell, characterized in that the aggregates while filling the interior of the porous nanoparticles.

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