KR20210091968A - Dye-sensitized thermoelectric generator utilizing bipolar conduction in single element - Google Patents

Abstract

The present invention provide a hybrid thermoelectric generator, in which a dye-sensitized solar cell unit and a thermoelectric structure unit are stacked in a vertical direction, a counter electrode of the dye-sensitized solar cell unit is an upper first electrode of the thermoelectric structure unit, the electrolyte of the dye-sensitized solar cell unit and the upper first electrode are in electrical contact in a vertical direction, and bipolar conduction is provided. According to the present invention, the hybrid thermoelectric generator according to the present invention minimizes a decrease in a charging rate, and remarkably improves the reduction rate of the redox pair of the electrolyte of the dye-sensitized solar cell unit, so as to exhibit excellent photoelectric conversion efficiency.

Description

Dye-sensitized hybrid thermoelectric generator using anode conductivity {DYE-SENSITIZED THERMOELECTRIC GENERATOR UTILIZING BIPOLAR CONDUCTION IN SINGLE ELEMENT}

The present invention relates to a dye-sensitized hybrid thermoelectric generator using anode conduction, and to a dye-sensitized hybrid thermoelectric generator materially hybridized so that the dye-sensitized solar cell and the thermoelectric generator exhibit high power generation efficiency.

A dye-sensitized solar cell (DSSC) is a solar cell that chemically generates power using the solar light absorption ability of a dye, and its manufacturing cost is lower than that of a conventional silicon solar cell or compound semiconductor solar cell, Compared to organic solar cells, the efficiency is high, and it is eco-friendly and has the advantage of being able to implement various colors. Due to these characteristics, it has applicability in application fields different from silicon-based solar cells, such as BIPV, and has been studied a lot until recently.

In general, a dye-sensitized solar cell includes an anode, a dye, an electrolyte, a counter electrode, and a transparent conductive electrode on a glass substrate. The cathode includes nanoparticles having a wide bandgap made of a semiconductor oxide or a metal oxide, and a dye of a monomolecular layer is usually adsorbed on the surface of the nanoparticles. Although the dye-sensitized solar cell has a relatively simple structure and has high economic efficiency at low cost compared to the conventional silicon-based solar cell, it has not been universalized due to low efficiency and reliability. Accordingly, in order to improve the efficiency of the dye-sensitized solar cell, studies have been conducted to introduce a tandem structure with other solar cells, to develop a dye, to improve the nanoparticle layer, or to improve the charge transfer characteristics in the device.

A thermoelectric generator (TEG) is a device that generates power by a temperature difference between both ends of the device, and the amount of power generation increases in proportion to the temperature difference between the ends. The TEG can be combined with the DSSC to release the thermal energy integrated in the DSSC and be used as a means for generating power at the same time. However, when the TEG and the DSSC are simply connected, there is a problem in that the fill factor (FF) of the DSSC-TEG hybrid thermoelectric generator is lowered.

Accordingly, the method of connecting DSSC and TEG can be an important factor for improving power generation performance. For example, in order to improve the performance of the DSSC-TEG hybrid power generation device, Korean Patent No. 10-0535343 discloses that a black body is formed on the thermoelectric semiconductor layer to improve the power generation efficiency, but it is difficult to obtain sufficient power generation performance with this method alone, and it is still The reduction rate of the redox pair of the electrolyte is low, so it is insufficient for use as a hybrid power generator.

Republic of Korea Patent Publication No. 10-0535343

The present invention to compensate for the above disadvantages is to hybridize the thermoelectric structure part and the dye-sensitized solar cell part, but hybridize at the material level rather than the structural level to minimize the decrease in the charge rate, and the dye-sensitized solar cell part An object of the present invention is to provide a hybrid thermoelectric generator having a synergistic effect that can significantly improve the reduction rate of the redox pair of the electrolyte.

As a result of many studies to achieve the above object, the hybrid thermoelectric generator according to the first aspect of the present invention is formed on the upper transparent electrode, the lower surface of the upper transparent electrode, and is made of a semiconductor oxide or metal oxide coated with dye. A dye-sensitized solar cell unit comprising a light absorption layer comprising nanoparticles made of, and an iodine-based electrolyte; and

A thermoelectric structure including an upper first electrode, a thermoelectric material formed under the upper first electrode, a solder layer formed under the thermoelectric material, and a lower second electrode formed under the solder layer; including a unit power generating element do,

It has been discovered and completed that the above-described problems can be solved by the iodine-based electrolyte of the dye-sensitized solar cell of the unit power plant and the upper first electrode of the thermoelectric structure are in electrical contact in a vertical direction.

As an example according to the present invention, the hybrid thermoelectric power generator may be a power generator array including a plurality of unit power generators, and different second electrodes of the power generator array may be electrically connected to each other.

As an example according to the present invention, the upper first electrode may include a platinum layer on the surface.

As an example according to the present invention, the upper first electrode may further include a nickel layer and an adhesive layer between the platinum layer and the surface of the upper first electrode.

As an example according to the present invention, the light absorption layer may be one in which a dye is coated on the surface of the titanium dioxide nanoparticles.

As an example according to the present invention, the titanium dioxide nanoparticles of the light absorption layer may be a mixture of light-reflective titanium dioxide nanoparticles and light-transmitting titanium dioxide nanoparticles, and may have a benign distribution.

As an example according to the present invention, the light absorption layer is formed by alternately screen printing a composition of a light reflective titanium dioxide nanoparticle composition and a light transmissive titanium dioxide nanoparticle on the lower surface of the upper transparent electrode to form a titanium dioxide nanoparticle layer ; heat-treating the titanium dioxide nanoparticle layer; and coating the heat-treated titanium dioxide nanoparticle layer with a dye.

As an example according to the present invention, the titanium dioxide nanoparticles may include rutile and anatase crystal structures at the same time.

As an example according to the present invention, a light-to-heat conversion unit may be further included between the dye-sensitized solar cell unit and the thermoelectric structure unit.

As an example according to the present invention, the light-to-heat conversion unit may include an acrylic polymer including an azo dye.

As an example according to the present invention, the thermoelectric material is Sb-Te-based, Bi-Te-based, Bi-Sb-Te-based, Co-Sb-based, Pb-Te-based, Ge-Tb-based, Si-Ge-based, Sm It may include any one selected from the group consisting of -Co-based compounds.

As an example according to the present invention, the upper first electrode of the thermoelectric structure may act as a lower electrode of the dye-sensitized solar cell, and the iodine-based electrolyte and the upper first electrode may be in direct electrical contact.

As an example according to the present invention, the thermoelectric material of the first hybrid thermoelectric generator of the power generator array is a p-type thermoelectric material, the thermoelectric material of the adjacent second hybrid thermoelectric generator is an n-type thermoelectric material, and the first hybrid thermoelectric power plant The second electrode of the ruler and the second electrode of the second hybrid thermoelectric generator may be electrically connected to each other with a conductive metal.

In the hybrid thermoelectric power generator according to the second aspect of the present invention, a dye-sensitized solar cell part and a thermoelectric structure part are vertically stacked, and the counter electrode of the dye-sensitized solar cell part is an upper first electrode of the thermoelectric structure part, and the dye-sensitized solar cell part is the upper first electrode. The electrolyte of the solar cell unit and the upper first electrode are in electrical contact in a vertical direction, and have positive electrode conductivity.

As an example according to the present invention, a plurality of hybrid thermoelectric generators may be included, and the lower second electrodes of different hybrid thermoelectric generators may be a generator element array electrically connected to each other.

The hybrid thermoelectric generator according to the present invention has a synergistic effect that can minimize the decrease in the charge rate by hybridizing the dye-sensitized solar cell unit and the thermoelectric structure at the material level, and also improve the reduction rate of the redox pair of the electrolyte of the dye-sensitized solar cell unit. have More specifically, since a hole activated by heat in the thermoelectric structure and electrons activated by light in the dye-sensitized solar cell unit simultaneously contribute to generation of current and voltage, excellent conversion efficiency may be exhibited. In addition, the upper first electrode of the thermoelectric structure unit is in electrical contact with the iodine-based electrolyte of the dye-sensitized solar cell unit in a vertical direction, thereby remarkably improving the reduction rate of the redox pair, significantly increasing the electron recombination lifetime, charge density, The charge diffusion coefficient and effective diffusion length can be significantly increased.

1 is a conceptual diagram schematically illustrating the structure of a dye-sensitized hybrid thermoelectric generator.
2 is an analysis result after the dye-adsorbed titanium dioxide nanoparticle layer was prepared by screen printing to apply the photo-cathode of DS-TEG.
3 is a test result of photovoltage measurement of a dye-sensitized hybrid thermoelectric generator (DS-TEG) and DSSC.
4 is a test result of evaluating the charge transport characteristics of a dye-sensitized hybrid thermoelectric generator (DS-TEG) and DSSC.
5 is a test result for evaluating the charge transfer effect of a dye-sensitized hybrid thermoelectric generator (DS-TEG).

Hereinafter, a carbon composite fiber having a crystalline conductive polymer shell of the present invention and a manufacturing method thereof will be described in detail with reference to the accompanying drawings.

The drawings introduced below are provided as examples in order to sufficiently convey the spirit of the present invention to those skilled in the art. Accordingly, the present invention is not limited to the drawings presented below and may be embodied in other forms, and the drawings presented below may be exaggerated to clarify the spirit of the present invention. Also, like reference numerals refer to like elements throughout.

At this time, if there is no other definition in the technical terms and scientific terms used, it has the meaning commonly understood by those of ordinary skill in the technical field to which this invention belongs, and the gist of the present invention in the following description and accompanying drawings Descriptions of known functions and configurations that may be unnecessarily obscure will be omitted.

Also, the singular forms used in the specification and appended claims may also be intended to include the plural forms unless the context specifically dictates otherwise.

In addition, in this specification, the expression "comprising" is an open-ended description having an equivalent meaning to expressions such as "having", "containing", "having" or "characterized by", and is not listed further. It does not exclude elements, materials or processes. Also, the expression "consisting substantially of..." means that other elements, materials, or processes not listed together with the specified element, material, or process are unacceptable for at least one basic and novel technical idea of the invention. It means that it can be present in an amount that does not significantly affect it. Also, the expression “consisting of” means that only the elements, materials, or processes described are present.

In addition, in this specification, the unit used without special mention is based on the weight, for example, the unit of % or ratio means weight % or weight ratio.

The hybrid thermoelectric generator according to the present invention is a first aspect, and includes an upper transparent electrode, a light absorption layer formed on a lower surface of the upper transparent electrode, and including nanoparticles made of a dye-coated semiconductor oxide or metal oxide, and an iodine-based device. a dye-sensitized solar cell unit including an electrolyte; and

A thermoelectric structure including an upper first electrode, a thermoelectric material formed under the upper first electrode, a solder layer formed under the thermoelectric material, and a lower second electrode formed under the solder layer; including a unit power generating element do,

The iodine-based electrolyte of the dye-sensitized solar cell part of the unit power plant and the upper first electrode of the thermoelectric structure part are in electrical contact in a vertical direction.

Referring to the structure shown in FIG. 1A , a hybrid thermoelectric generator (DSSC-TEG) having a conventional tandem structure in which a dye-sensitized solar cell and a thermoelectric structure are combined is illustrated. In the case of the conventional structure shown in FIG. 1( a ), a plurality of thermoelectric structures are coupled to the lower part of one dye-sensitized solar cell. The dye-sensitized solar cell includes an upper transparent electrode and a lower electrode on the upper and lower portions, respectively, and electrons activated by light move to the upper transparent electrode, and the hole moves to the lower electrode, and then the upper first part of the electrically connected thermoelectric structure move to the electrode. According to the structure shown in Fig. 1(a), the p-type thermoelectric structure is related to the movement of holes as a majority carrier, and the n-type thermoelectric structure and the dye-sensitized solar cell are the majority carriers and are responsible for the movement of electrons. is related Accordingly, each thermoelectric structure generates unipolar conduction, and the interface between the thermoelectric structure and the dye-sensitized solar cell forms an electrode junction connecting the anode and the cathode of each device.

On the other hand, in the case of the hybrid thermoelectric generator (DS-TE) according to the present invention, bipolar conduction occurs because holes and electrons both contribute to the generation of current and voltage. The movement of carriers in the hybrid thermoelectric generator (DS-TE) according to the present invention will be described with reference to the conceptual diagram shown in FIG. 1(b).

Specifically, long-wavelength photons passing through the dye-sensitized solar cell are selectively converted into heat by the light-to-heat conversion layer, and heat is transferred to the thermoelectric structure. In the thermoelectric structure, electrons may be supplied to the iodine-based electrolyte through vertical electrical contact between the iodine-based electrolyte of the dye-sensitized solar cell and the upper first electrode of the thermoelectric structure, and the reduction reaction of triiodine may be promoted. Since the reduction reaction of triiodine is the biggest factor inhibiting the charge transfer of the dye-sensitized solar cell, the hybrid thermoelectric power generator (DS-TE) according to the present invention performs the reduction reaction of triiodine by materially hybridizing the thermoelectric structure. It is effectively promoted to realize significantly higher power conversion efficiency (PCE) compared to the hybrid thermoelectric generator (DSSC-TEG) hybridized at the structural level.

In one embodiment of the present invention, the hybrid thermoelectric power generator may include a plurality of unit power generators and are spaced apart from each other, and adjacent second electrodes of the power generator array may be electrically connected to each other.

In a preferred embodiment, the thermoelectric material of the first hybrid thermoelectric generator constituting the power generator array may be a p-type thermoelectric material, and the thermoelectric material of the adjacent second hybrid thermoelectric generator may be an n-type thermoelectric material. In this case, the second electrode of the first hybrid thermoelectric generator and the second electrode of the second hybrid thermoelectric generator may be electrically connected to each other with a conductive metal.

The upper transparent electrode of the dye-sensitized solar cell means a transparent conducting electrode (TCO: transparent conducting oxide). The conductive electrode is not limited to the above material, and a conductive material known in the art may be used without limitation. For example, the upper transparent electrode is a conductive film containing FTO (F-doped SnO2: SnO2:F), ITO, a metal electrode having an average thickness of 1 to 1000 nm, a metal nitride, a metal oxide, a carbon compound, or a conductive polymer. can

Nanoparticles made of a semiconductor oxide or a metal oxide included in the light absorption layer are, for example, silver tin (Sn) oxide, antimony (Sb), niobium (Nb) or fluorine-doped tin (Sn) oxide, indium (In) Oxide, tin-doped indium (In) oxide, zinc (Zn) oxide, aluminum (Al), boron (B), gallium (Ga), hydrogen (H), indium (In), yttrium (Y), titanium ( Ti), silicon (Si) or tin (Sn) doped zinc (Zn) oxide, magnesium (Mg) oxide, cadmium (Cd) oxide, magnesium zinc (MgZn) oxide, indium zinc (InZn) oxide, copper aluminum ( CuAl) oxide, silver (Ag) oxide, gallium (Ga) oxide, zinc tin oxide (ZnSnO), titanium oxide (TiO2) and zinc indium tin (ZIS) oxide, nickel (Ni) oxide, rhodium (Rh) oxide, Russe Nium (Ru) oxide, iridium (Ir) oxide, copper (Cu) oxide, cobalt (Co) oxide, tungsten (W) oxide, titanium (Ti) oxide, zirconium (Zr) oxide, strontium (Sr) oxide, lanthanum (La) oxide, vanadium (V) oxide, molybdenum (Mo) oxide, niobium (Nb) oxide, aluminum (Al) oxide, yttnium (Y) oxide, scandium (Sc) oxide, samarium (Sm) oxide , may be one or more nanoparticles selected from the group consisting of strontium titanium (SrTi) oxide and mixtures thereof.

Specifically, the light absorption layer may be a dye coated on the surface of the titanium dioxide nanoparticles. Preferably, the titanium dioxide nanoparticles of the light absorption layer may have a bimodal distribution as a mixture of light reflective titanium dioxide nanoparticles and light transmissive titanium dioxide nanoparticles.

The titanium dioxide nanoparticles of the light absorption layer may have a structure of a nanoparticle layer, and may have a thickness of 1 to 500 μm, preferably 10 to 100 μm.

The average diameter of the light reflective titanium dioxide nanoparticles is 100 nm or more, specifically 100 to 500 nm, more specifically 100 to 200 nm, the average diameter of the light-transmitting titanium dioxide nanoparticles is 5 to 50 nm, preferably 5 to 30 nm, more preferably 10 to 25 may be nm.

The light absorption layer is formed by screen-printing a light reflective titanium dioxide nanoparticle composition and a light transmitting titanium dioxide nanoparticle composition on the lower surface of the upper transparent electrode alternately to form a titanium dioxide nanoparticle layer; heat-treating the titanium dioxide nanoparticle layer; and coating the heat-treated titanium dioxide nanoparticle layer with a dye.

The light-reflective or light-transmitting titanium dioxide nanoparticle composition may be a paste-type composition including titanium dioxide nanoparticles, a binder, and a solvent.

The alternating lamination of the light reflective titanium dioxide nanoparticle composition and the light transmissive titanium dioxide nanoparticle composition may be performed 1 to 1000 times, preferably 5 to 500 times, but this is only an example and is not limited thereto.

The heat treatment step may be 250 to 600 degrees, preferably 300 to 500 degrees.

The titanium dioxide nanoparticle layer prepared through heat treatment may include rutile and anatase crystal structures at the same time. The titanium dioxide nanoparticles having the rutile and anatane crystal structures may be in a weight ratio of 2:8 to 8:2. In general, titanium dioxide with anatase crystal structure has low symmetry and high distortion, so it can show high efficiency. However, in the case of rutile crystal structure, it has a larger surface area than pure anatase crystal structure, so it can receive electrons from a larger number of dye molecules. As a result, when the titanium dioxide of the rutile crystal is mixed with the titanium dioxide of the anatase crystal structure, electron transfer from the conduction band edge of the rutile crystal structure to the trapping site of the anatase crystal ( electron migration) can be significantly increased. Accordingly, in the case of a device including a titanium dioxide nanoparticle layer simultaneously containing rutile and anatase crystal structures, short-circuit current and power conversion efficiency may be remarkably improved. However, as described above, titanium dioxide having a rutile crystal structure has a large surface area and can receive more electrons from the adsorbed dye, but has low electron mobility and may cause current loss due to high resistivity. That is, the increased electron injection amount due to the large surface area of titanium dioxide having a rutile crystal structure and the amount of current loss due to high specific resistance are in a trade-off relationship with each other, so that dioxide having a rutile and anatase crystal structure Titanium nanoparticles preferably satisfy the above-described weight ratio.

The dye has a band gap of 1.55 eV to 3.1 eV and can absorb visible light, and any dye used in a dye-sensitized solar cell may be used without limitation. Specific examples may be an organic-inorganic complex dye containing a metal or a metal complex, an organic dye, or a mixture thereof, and more specifically, aluminum (Al), platinum (Pt), palladium (Pd), europium (Eu), lead (Pb), iridium (Ir), ruthenium (Ru), and an organic-inorganic complex dye or silane-based organic dye containing an element selected from the group consisting of complexes thereof. Preferably, the ruthenium-based heteroaryl-based dye may be N719 dye.

The electrolyte may be uniformly dispersed in the light absorption layer while filling a space between the upper transparent electrode and the upper first electrode of the thermoelectric structure. Like a conventional dye-sensitized solar cell, when sunlight is incident, photons passing through the upper transparent electrode are absorbed by the dye, and the dye becomes excited by absorption of sunlight to generate electrons, and the excited electrons are titanium dioxide nano The particles are transported to the conduction band and flow through the upper transparent electrode to the external circuit to deliver electrical energy. And the dye oxidized by sunlight absorption receives electrons from the electrolyte solution and is reduced to its original state. In the present invention, unlike a conventional dye-sensitized solar cell, the electrolyte receives electrons from the upper first electrode of the thermoelectric structure by oxidation-reduction and transfers it to the dye of the light absorption layer, which can be used in conventional dye-sensitized solar cells. If it is a thing, it will not specifically limit. As a specific example, it may be an ^{iodine-based electrolyte (I -} /I ^{3- ).}

In a preferred embodiment, the upper first electrode of the thermoelectric structure may act as a lower electrode of the dye-sensitized solar cell, and the iodine-based electrolyte and the upper first electrode may be in direct electrical contact. That is, the dye-sensitized solar cell unit has an upper transparent electrode, but does not include a separate independent electrode at the lower portion, and the upper first electrode included in the thermoelectric structure unit may be used as a lower electrode of the dye-sensitized solar cell unit. As the dye-sensitized solar cell unit utilizes the upper first electrode of the thermoelectric structure as a lower electrode, electrons flow from the thermoelectric structure to the electrolyte of the dye-sensitized solar cell, and the reduction barrier of the redox pair can be lowered to increase the reduction rate. there is. Through this, the reduction rate of triiodine constituting the electrolyte is increased, thereby solving the factor of delay in carrier transport in the dye-sensitized solar cell unit, and through this, it is possible to bring about a significant increase in power conversion efficiency (PCE).

A light-to-heat conversion unit may be further included between the dye-sensitized solar cell unit and the thermoelectric structure unit. The light-to-heat conversion unit may be in the form of a polymer film that converts light into heat, and specifically may include an acrylic polymer including an azo dye. In this case, the light-to-heat conversion unit may be formed in a region where the active region (titanium dioxide nanoparticle layer) is not formed in the dye-sensitized solar cell unit.

The upper first electrode of the thermoelectric structure may include a platinum layer on a surface thereof. The thickness of the platinum layer may be 50 nm to 2 μm, preferably 500 nm to 1 μm. In addition, the upper first electrode may further include a nickel layer and an adhesive layer between the platinum layer and the surface of the upper first electrode. For example, the adhesive layer may be a chromium/gold (Cr/Au) adhesive layer. Since the nickel layer is included in the lower portion of the platinum layer, the contact resistance between the thermoelectric material and the platinum layer can be reduced.

The thermoelectric material is from the group consisting of Sb-Te-based, Bi-Te-based, Bi-Sb-Te-based, Co-Sb-based, Pb-Te-based, Ge-Tb-based, Si-Ge-based, and Sm-Co-based compounds. It may include any one selected.

Specifically, in the case of the P-type thermoelectric material among the thermoelectric materials, an antimony-tellurium-based (Sb _x Te _1-x ) or a bismuth-antimony-tellurium _{-based (Bi y} Sb _2-y Te ₃ ) compound (x is 0 ≤ x) ≤ 1, y may be a material of 0 ≤ y ≤ 2).

In the case of the N-type thermoelectric material, a bismuth-tellurium-based (Bi _x Te _1-x ) or a bismuth-tellurium-based (Bi ₂ Te _3-y Se _y ) compound (x may be 0 ≤ x ≤ 1, y may be a material of 0 ≤ y ≤ 2).

The size and shape of the thermoelectric material may be appropriately designed in consideration of the use of the thermoelectric element. As a specific example, the N-type and P-type thermoelectric materials may have the same or different shapes and sizes. More specifically, the N-type and P-type thermoelectric materials may be, independently of each other, a plate-shaped or columnar shape, and a cross-section in the thickness or longitudinal direction has a curved shape such as a circular shape, an elliptical shape, or a triangular, rectangular, or pentagonal shape. It may have an angular shape, but is not limited thereto. The thickness of the N-type or P-type thermoelectric material may be in the order of several tens of μm to several tens of mm. In addition, the cross-sectional area of the N-type or P-type thermoelectric material column may have an area of the order of ^{several hundred square μm 2} to several square cm ^{2 .} As a practical example, the N-type or P-type thermoelectric material may have a thickness of 150 μm to 8 mm, specifically, a thickness of 200 μm to 4 mm, but the physical shape or size of the thermoelectric material. is not limited by

The electrical conductivity of the thermoelectric material may be 1.0×10 ⁴ S/m or more, preferably 1.0×10 ⁵ S/m or more, and may be, without limitation, 1.0×10 ⁷ S/m or less.

The present invention is a second aspect, wherein the dye-sensitized solar cell part and the thermoelectric structure part are vertically stacked, the counter electrode of the dye-sensitized solar cell part is the upper first electrode of the thermoelectric structure part, and the electrolyte of the dye-sensitized solar cell part and the upper first electrode are in electrical contact in a vertical direction, and provide a hybrid thermoelectric generator, characterized in that it has anode conductivity.

A dye-sensitized solar cell typically essentially includes an upper transparent electrode, a light absorption layer, an electrolyte, and a lower counter electrode, and may optionally include an upper transparent substrate, a sealing material, and a packaging material. However, the hybrid thermoelectric generator according to the present invention may be characterized in that it does not include a lower counter electrode in the dye-sensitized solar cell unit, and is materially hybridized by the upper first electrode of the thermoelectric structure becoming the lower counter electrode. Through this structure, the electrolyte of the dye-sensitized solar cell unit and the upper first electrode can make electrical contact in a vertical direction, and in the case of a structural hybrid, it has unipolar conductivity, whereas it can have positive conductivity through material hybridization. there is.

Hereinafter, a carbon composite fiber having a crystalline conductive polymer shell according to the present invention and a manufacturing method thereof will be described in more detail through Examples. However, the following examples are only a reference for describing the present invention in detail, and the present invention is not limited thereto, and may be implemented in various forms.

[Example]

1) Preparation of titanium dioxide nanoparticle layer

The titanium dioxide nanoparticle layer used to prepare DS-TEG and DSSC was prepared to a thickness of about 50 μm by screen printing. In one embodiment, it was laminated using a titanium dioxide nanoparticle paste (Solaronix). The light reflective paste has a particle size of 100 nm or more, and the photon transmissive paste has a particle size of 15 to 20 nm. The photon reflective paste and the photon transmissive paste are successively applied to an FTO-coated glass substrate by screen printing. laminated. When heat-treated in an oven at 380° C. for 60 minutes, the sheet resistance was found to be about 34 Ω/□ ( FIG. 2( b )). When the nanostructured titanium dioxide film is observed by SEM, it can be confirmed that particles having a size of 50 to 150 nm are dispersed as shown in the right photo of FIG. 2(a). In addition, when the titanium dioxide film formed by the screen printing method was measured by XRD, it was confirmed that TiO2 crystal phases of anatase and rutile were mixed (FIG. 2(c)).

2) DS-TEG manufacturing

The DS-TEG was divided into a DSSC part that transports excess electrons through light absorption and a TEG part that transports thermally activated holes.

DSSC part: First, a titanium dioxide nanoparticle paste (Solaronix) is coated on a glass substrate (about 2 mm thick) by screen printing, and then heat-treated on a hot plate at 380° C. for 60 minutes, and a titanium dioxide nano-particle layer ( After forming a thickness: about 30 μm), it was immersed in N719 dye solution for 12 to 24 hours to prepare a dye-dyed titanium dioxide nanoparticle layer. Next, a double-sided tape-type light-to-heat conversion layer and a thermoplastic resin were sequentially attached to the remaining part except for the active area where the dyed titanium dioxide nanoparticle layer was located on the glass substrate.

In this case, the light-to-heat conversion layer was prepared using an acrylic double sided tape film having a thickness of about 5 μm, and the area of the prepared light-to-heat conversion layer was the same as that of the TEG part. First, Basic black 7 was prepared as a black coloring dye and Basic black 3 was prepared as an AZO dye, and then the dyes were diluted to 0.5 wt% in distilled water at 40 °C. Next, while the diluted dye solution was heated to 100° C. at a temperature increase rate of 1° C./min using a hot plate, acetic acid was added to the diluted dye solution so that the pH of the solution was 3 to 4. Finally, the acrylic double-sided tape film was immersed in the solution and maintained at the same temperature for 40 minutes, then slowly lowered to room temperature, and then washed with deionized water.

TEG part: First, a P-type thermoelectric material with a size of 2 mm × 2 mm × 5 mm (Bi _0.5 Sb _1.5 Te ₃ ), an n-type thermoelectric material with a size of 2 mm × 2 mm × 5 mm (Bi ₂ Sb _2.7 Te _0.3 ) and a Cu film having a size of 3 mm × 10 mm × 75 μm was prepared. Next, after soldering using a Cu film so that one side of the P-type thermoelectric material and one side of the N-type thermoelectric material are connected, one side (A side) on which the Cu film is formed in the thermoelectric material-Cu film unit is applied to a polyimide tape (PI tape), etc. After attaching a sacrificial substrate and turning it over so that the other side (B side) on which the Cu film is not formed is exposed, polydimethylsiloxane (PDMS) is placed in the empty space around the thermoelectric material (P-type and N-type). was filled. At this time, after attaching the TEG part and the DSSC part, a feed through with a diameter of about 1 mm through which a syringe needle can pass was formed in the PDMS so that electrolytes could be injected. Finally, Ni, Cr, Au and Pt were sequentially deposited on the exposed surface (B surface) of the thermoelectric materials (P-type and N-type) by using a physical vapor deposition method.

DS-TEG device: After pressurizing the manufactured DSSC part and TEG part using a heat gun and a pre-attached thermoplastic resin, I ^- /I ₃ ^- electrolyte is injected through a feed through A DS-TEG device was manufactured by sealing the entrance.

3) Measurement of photoelectric properties

Next, photo-voltage transient decay was measured to confirm the operation of the thermoelectric structure in DS-TEG. A large signal was obtained by measuring the photovoltage by on/off of the base light of 100 mW/cm2 intensity, and the perturbation light (with a red LED as the light source for charge transport characteristics in the device for a short time) Perturbation light) was measured to obtain a small signal. Perturbation light was irradiated to the device in quarter pulses for 5 cycles and the base light was on. Each cycle period and pulse width were optimized for 1 s and 100 microseconds. A TE cooler (TEC) was mounted on the bottom of the DS-TEG, and a temperature difference (ΔT) between the thermoelectric structure and the DS-TEG was formed while maintaining 25°C. For accurate comparison of TEC, the same temperature conditions were applied to DSSC measurements.

Referring to the photovoltage measurement result of FIG. 3B , it can be seen that the large and small signals of DSSC and DS-TEG overlap. The result of 5 cycles of perturbation light irradiated in the base light on state is the same as the dotted line in FIG. 3(b). For DS-TEG, the open-circuit voltage (Voc) of 0.86V was reached in 2.39 seconds when the base light was on, and Voc was saturated to a minimum value at about 9.75 seconds when the base light was off. On the other hand, in the case of DSSC, it took 1.95 seconds to reach 0.80V from the base light off state and 4.21 seconds to reach the steady state.

When the base light is on, the Voc difference between DSSC and DS-TEG is about 60 mV, and has a Seebeck coefficient of about 0.2 mV due to ΔT formed in the thermoelectric structure, resulting in a synergistic effect in DS-TEG can confirm that it does.

In addition, the longer fall times appear in DS-TEGs, suggesting that the recombination rate of electrons is significantly reduced.

In addition, the results of small signals are shown in FIGS. 3(c) and 3(d). The Voc of DSSC and DS-TEG is about 10 mV, and the photovoltage rise time is about 25 milliseconds in the LED-on state. . However, the fall time showed a large difference, about 32 milliseconds in DSSC and 72 milliseconds in DS-TEG. The temporary change is due to irradiation of perturbated light with weak beam energy, suggesting a change in charge transport properties within the device.

In addition, charge transport characteristics in DSSC and DS-TEG were confirmed from the results of photovoltage and photocurrent transient attenuation. Figure 4(b) shows the transient decay of the current density after the base light is turned off. The diffusion coefficient of the DSSC and DS-TEG according to the electron recombination lifetime and current density by measuring the possible charge densities of DSSC and DS-TEG under Voc condition. saved This is obtained by integrating the current density after turning off the base light and the perturbation light from the Voc condition until Voc and JSC are saturated to their minimum values.

The calculation is by estimation of the transient decay of the current density measured under standard AM 1.5G conditions as a first-order exponential function, and by integration with time, the excess value of charge was obtained at Voc conditions of DS-TEG 24.87 mC and DSSC 2.47 mC. (Fig. 4(b)). This result indicates that DS-TEG and DSSC have charge densities of ^{3.1×10 19} cm ^-3 and 3.0×10 ¹⁸ cm ^{-3 .} The results obtained by calculating the charge densities of DS-TEG and DSSC under various operating conditions by the above calculation are shown in FIG. 4(c) .

In addition, the electron recombination lifetime was calculated by extracting the fall time from the small signal. As a result, it was confirmed that DS-TEG exhibited about 22 times higher recombination lifetime than DSSC under the condition ^{of charge density of about 8.9×10 18} cm ^{-3 (FIG. 4(d)).} In addition, DS-TEG (51.53 msec) showed 2.13 times longer lifespan than DSSC (24.21 msec) under the same AM 1.5G irradiation condition. In addition, DS-TEG exhibited about 10 times higher charge density under sunlight conditions, even compared to a device employing a 50 μm-thick titanium dioxide film.

In addition, the effective thickness of the charge generation layer could be optimized by analyzing the charge transport characteristics of DS-TEG. FIG. 4(e) shows the result of calculating the electron diffusion coefficients of DS-TEG and DSSC with respect to the effective thickness of the charge generating layer. From the above results, it can be seen that DS-TEG exhibits a longer recombination lifetime and a larger diffusion coefficient than DSSC. In general, as the thickness of the titanium dioxide film increases, the resistance of the nanostructured network increases. That is, the increase time of the photovoltage attenuation in the small signal is significantly increased. However, as in FIG. 3(d), there is little difference between DS-TEG and DSSC in increasing time. Therefore, it was confirmed that the effective charge density of the DS-TEG was significantly increased, and the effective thickness of the charge generation layer was not a factor of increasing the electrical resistance in the titanium dioxide network.

The electron recombination in triiodine is rapidly reduced by the thermoelectric structure, and the effective diffusion length increases can be calculated by Einstein's relational expression (FIG. 4(f)). For DS-TEG, the effective diffusion length was found to exceed the thickness of the titanium dioxide film at a bias of about 0.5 V, which indicates that electron trapping is effective. On the other hand, in the case of DSSC, it was found that the effective diffusion length did not exceed the thickness of the titanium dioxide film under bias conditions, suggesting that electrons emitted from the dye exhibit low transport efficiency.

In addition, the output characteristics of DS-TEG were evaluated by confirming the inhibition of triiodine and electron recombination in the electrolyte for the thermoelectric structure. In addition, it was confirmed that effective electron trapping occurred from the result that the effective charge density increased and the electron diffusion coefficient (Dn) and the carrier diffusion length (Ln) were increased. Therefore, it can be seen that DS-TEG exhibits improved electrical properties than DSSC.

The J-V curves of DS-TEG and DSSC are shown in Fig. 5(a). DS-TEG shows a higher Voc than DSSC, because ΔT is formed through the thermoelectric structure. In addition, as the effective charge density increased and the number of non-equilibrium carriers increased, the redox potential energy of the quasi-fermi level and the electrolyte of titanium dioxide increased, resulting in a further increase in Voc.

The Voc of DS-TEG was 0.89V, which was 0.1V higher than that of DSSC, and JSc was 20.7mA/cm2, which showed an increase of 3.2mA/cm2 compared to DSSC under standard AM 1.5G irradiation conditions.

In particular, the FF of DS-TEG reached 77.2%, indicating a decrease of only 1.3% compared to before hybridization. This is a result of the successful hybridization of a single thermoelectric structure and a single dye-sensitized solar cell, showing a synergistic effect, which cannot be obtained in a simple DSSC-TEG bonding structure in which hundreds of thermoelectric elements are connected to a dye-sensitized solar cell.

Due to the high FF, the maximum power density increased by 2.7mW/cm2 to achieve 10.8mW/cm2, which is a result showing a power conversion efficiency of 10.8%.

The thermoelectric structure of the DS-TEG exhibited an increase in external quantum efficiency in the short wavelength region of 800 nm or less through charge collection of a single dye-sensitized solar cell (FIG. 5(b)). In addition, it was shown that power is transmitted to the load using thermal-activated holes by the light-to-heat conversion layer of the thermoelectric structure in the long wavelength region of 800 nm or more, which cannot be absorbed by a single dye-sensitized solar cell. In the p-type thermoelectric structure, thermally active holes move from a high temperature region to a low temperature region, and electrons are supplied to the electrolyte of the dye-sensitized solar cell unit to lower the reduction barrier of the redox pair and increase the reduction rate. This resulted in higher EQE compared to conventional dye-sensitized solar cells in the entire wavelength region. From these results, it was confirmed that DS-TEG is a device that can overcome the PCE limitation in conventional DSSC.

Although preferred embodiments of the present invention have been described above, it is clear that the present invention can use various changes, modifications and equivalents, and can be equally applied by appropriately modifying the above embodiments. Accordingly, the above description is not intended to limit the scope of the present invention, which is defined by the limits of the following claims.

Claims (15)

upper transparent electrode,
a light absorption layer formed on the lower surface of the upper transparent electrode and comprising nanoparticles made of a semiconductor oxide or metal oxide coated with a dye; and
A dye-sensitized solar cell unit including an iodine-based electrolyte; and
upper first electrode;
a thermoelectric material formed under the upper first electrode;
a solder layer formed under the thermoelectric material; and
a thermoelectric structure including a lower second electrode formed under the solder layer;
The hybrid thermoelectric generator, characterized in that the iodine-based electrolyte of the dye-sensitized solar cell of the unit power generator and the upper first electrode of the thermoelectric structure are in electrical contact in a vertical direction. According to claim 1,
The hybrid thermoelectric generator is a power generator array including a plurality of unit power generators, and the different second electrodes of the power generator array are electrically connected to each other. According to claim 1,
The upper first electrode is a hybrid thermoelectric generator including a platinum layer on the surface. 4. The method of claim 3,
The upper first electrode may further include a nickel layer and an adhesive layer between the platinum layer and the upper first electrode surface. According to claim 1,
The light absorbing layer is a hybrid thermoelectric generator in which a dye is coated on the surface of the titanium dioxide nanoparticles. 6. The method of claim 5,
The titanium dioxide nanoparticles of the light absorbing layer are hybrid thermoelectric generators that have a bimodal distribution as a mixture of light reflective titanium dioxide nanoparticles and light transmissive titanium dioxide nanoparticles. 6. The method of claim 5,
The light absorption layer,
forming a titanium dioxide nanoparticle layer by alternately screen-printing a composition of a light reflective titanium dioxide nanoparticle composition and a light transmissive titanium dioxide nanoparticle composition on the lower surface of the upper transparent electrode;
heat-treating the titanium dioxide nanoparticle layer; and
coating the heat-treated titanium dioxide nanoparticle layer with a dye;
A hybrid thermoelectric generator that is manufactured through 6. The method of claim 5,
The titanium dioxide nanoparticle is a hybrid thermoelectric generator that includes a rutile and anatase crystal structures at the same time. According to claim 1,
A hybrid thermoelectric generator further comprising a light-to-heat conversion unit between the dye-sensitized solar cell unit and the thermoelectric structure unit. 10. The method of claim 9,
The light-to-heat conversion unit is a hybrid thermoelectric generator comprising an acrylic polymer including an azo dye. According to claim 1,
The thermoelectric material is from the group consisting of Sb-Te-based, Bi-Te-based, Bi-Sb-Te-based, Co-Sb-based, Pb-Te-based, Ge-Tb-based, Si-Ge-based, and Sm-Co-based compounds. A hybrid thermoelectric generator comprising any one selected. According to claim 1,
The upper first electrode of the thermoelectric structure unit operates as a lower electrode of the dye-sensitized solar cell unit, and the iodine-based electrolyte and the upper first electrode are in direct electrical contact with each other. 3. The method of claim 2,
The thermoelectric material of the first hybrid thermoelectric generator of the power generator array is a p-type thermoelectric material, the thermoelectric material of the adjacent second hybrid thermoelectric generator is an n-type thermoelectric material, and the second electrode and the second hybrid of the first hybrid thermoelectric generator The second electrode of the thermoelectric generator is a hybrid thermoelectric generator that is electrically connected to each other with a conductive metal. The dye-sensitized solar cell part and the thermoelectric structure part are stacked in a vertical direction,
The counter electrode of the dye-sensitized solar cell part is an upper first electrode of the thermoelectric structure part, and the electrolyte of the dye-sensitized solar cell part and the upper first electrode are in electrical contact in a vertical direction, and have anode conductivity. thermoelectric power plant. 15. The method of claim 14,
A hybrid thermoelectric generator comprising a plurality of hybrid thermoelectric generators, wherein the lower second electrodes of the different hybrid thermoelectric generators are generator element arrays electrically connected to each other.

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