Organic solar cell comprising semiconducting swnts and method for manufacturing same

Abstract

The present invention relates to an organic solar cell comprising semiconducting single wall carbon nanotubes (SWNTs) and a method for manufacturing same. The solar cell comprises a substrate, a first electrode layer formed on the substrate, a charge transport layer formed on the first electrode layer, an active layer formed on the charge transport layer, a hole transport layer formed on the active layer, and a second electrode layer formed on the hole transport layer, wherein the active layer comprises an organic material having a donor-acceptor structure and semiconducting SWNTs. According to the present invention, SWNTs are purified using a conjugated polymer and a solvent, semiconducting SWNTs having a specific chirality are obtained, and the semiconducting SWNTs are then added to an active layer, thereby supplementing a charge transfer path and improving photoelectric conversion efficiency. In addition, a light absorption spectrum is expanded through excellent electrical properties and mechanical stability of the SWNTs, and long-term stability and performance of the solar cell are maximized. The present invention provides improved efficiency and durability relative to existing organic solar cells, and can be applied to next-generation high-performance photoelectric devices.

Description

Organic solar cell containing semiconducting SWNTs and method for manufacturing the same

[0001] The present invention relates to an organic solar cell comprising a semiconducting SWNT and a method for manufacturing the same.

[0002] Solar cells are attracting global attention as a sustainable energy source, and various studies are being conducted to simultaneously improve efficiency and economic feasibility. Currently, solar cell technology is mainly divided into silicon-based crystalline solar cells and organic solar cells, and each technology requires improvement in terms of efficiency, stability, and manufacturing costs. In particular, extending the diffusion length of excitons is emerging as a major challenge.

[0003] Single-walled carbon nanotubes (SWNTs) are nanomaterials with excellent electrical, optical, and mechanical properties, and are attracting attention as additives that enhance electron transfer and charge transport in solar cells. In particular, the semiconducting fraction of SWNTs can significantly improve electrical performance through its bandgap characteristics and high charge mobility. However, since synthesized SWNTs contain a mixture of metallic and semiconducting fractions, high-purity separation of semiconducting SWNTs is essential to improve solar cell efficiency.

[0004] Furthermore, conventional SWNT-based solar cells have faced limitations in optimizing the uniform dispersion and charge transport characteristics of SWNTs; to address these issues, SWNT purification technology utilizing conjugated polymers and non-polar solvents is being proposed as a new alternative. The present invention aims to improve charge transport characteristics and enhance the efficiency and stability of solar cells by utilizing semiconducting SWNTs with high purity and low defects as active layer or electrode materials for solar cells.

[0005] To solve the above-mentioned problems, the present invention aims to provide an organic solar cell comprising semiconducting SWNTs and a method for manufacturing the same.

[0006] The present invention provides an organic solar cell comprising a semiconductor SWNT, comprising: a substrate; a first electrode layer formed on the substrate; a charge transport layer formed on the first electrode layer; an active layer formed on the charge transport layer; a hole transport layer formed on the active layer; and a second electrode layer formed on the hole transport layer.

[0007] The above active layer may include a semiconducting SWNT (Single Wall Carbon Nanotube).

[0008] The first electrode layer may be one or more selected from the group consisting of ITO (Indium Tin Oxide), FTO (Fluorine-doped Tin Oxide), AZO (Aluminum-doped Zinc Oxide), and GZO (Gallium-doped Zinc Oxide).

[0009] The charge transport layer may be composed of one or more materials selected from the group consisting of zinc oxide (ZnO), titanium oxide (TiO2) and stenite (SnO2).

[0010] The above active layer may have a donor-acceptor structure.

[0011] The above active layer may include PM6(Poly[(2,6-(4,8-bis(5-(2-ethylhexyl)-4-fluorothiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione))]) as a donor.

[0012] The above active layer may comprise Y6(2,2'-((2Z,2'Z)-((12,13-bis(2-ethylhexyl)-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2",3":4',5']thieno[2',3':4,5]pyrrolo[3,2-g]thieno[2',3':4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene)dimalononitrile)) as an acceptor.

[0013] The above hole transport layer may be composed of one or more selected from the group consisting of MoO3, WO3, V2O5, and CoO4.

[0014] A method for manufacturing an organic solar cell including the above-mentioned semiconducting SWNT may comprise: A) a step of purifying SWNTs to obtain semiconducting SWNTs; B) a step of forming a first electrode layer on a substrate and washing it; C) a step of applying a first precursor solution and heat-treating it on the first electrode layer to form a charge transport layer; D) a step of applying a second precursor solution on the charge transport layer to form an active layer; E) a step of forming a hole transport layer on the active layer; and F) a step of forming a second electrode layer on the hole transport layer.

[0015] The above second precursor solution may include PM6, Y6, and semiconducting SWNTs.

[0016] The above step A) may include a) mixing a conjugated polymer in a solvent; b) adding and mixing single-wall carbon nanotubes; c) separating the liquid phase from the mixture; d) removing the solvent from the separated liquid phase; and e) recovering semiconducting single-wall carbon nanotubes.

[0017] The above conjugated polymer may comprise one or more selected from PFDD (Poly(9,9-di-n-dodecylfluorenyl-2,7-diyl)) or PFO-Bpy (Poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(9,9-bis(6'-N,N,N-trimethylammonium)hexylfluorenyl-2,7-diyl dibromide)]).

[0018] The above solvent may include one or more selected from Decalin, Tetralin, m-xylene, p-xylene, Tetrahydrofuran (THF), Chlorobenzene, Mesitylene, and Cumene.

[0019] The organic solar cell comprising semiconductor SWNTs according to the present invention and the method for manufacturing the same have the effect of improving open circuit voltage, short-circuit current density, and photoelectric conversion efficiency by enhancing charge mobility through the semiconductor SWNTs.

[0020] Figure 1 is a schematic diagram showing a method for manufacturing an organic solar cell.

[0021] Figure 2 is a schematic diagram showing a method for purifying semiconducting SWNTs.

[0022] Figure 3 shows the UV-Vis light absorption spectrum of chiral semiconductor SWNTs dispersed in toluene.

[0023] Figure 4 shows the voltage-current curve of an organic solar cell.

[0024] An organic solar cell comprising a semiconducting SWNT according to the present invention and a method for manufacturing the same will be described in detail below. The drawings presented below are provided as examples to ensure that the concept of the present invention is sufficiently conveyed 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 concept of the present invention. In this case, unless otherwise defined, technical and scientific terms used in the present invention have the meaning commonly understood by those skilled in the art to which this invention pertains, and descriptions of known functions and configurations that could unnecessarily obscure the essence of the present invention are omitted in the following description and attached drawings.

[0025] The present invention provides an organic solar cell comprising a semiconductor SWNT, comprising: a substrate; a first electrode layer formed on the substrate; a charge transport layer formed on the first electrode layer; an active layer formed on the charge transport layer; a hole transport layer formed on the active layer; and a second electrode layer formed on the hole transport layer.

[0026] The substrate may serve as a structural base for supporting a solar cell, act as an electrical insulator, and possess transparency and thermal stability. The substrate may be, for example, any one selected from the group consisting of glass, PET (Polyethylene terephthalate), PEN (polyethylene naphthalate), and silicon (Si).

[0027] The first electrode layer is an electrode for collecting photocurrent and requires transparency and conductivity, and it is necessary to minimize electrical loss at the contact surface with the charge transport layer. Accordingly, the first electrode layer may be one or more selected from the group consisting of ITO (Indium Tin Oxide), FTO (Fluorine-doped Tin Oxide), AZO (Aluminum-doped Zinc Oxide), and GZO (Gallium-doped Zinc Oxide).

[0028] The charge transport layer selectively transfers electrons generated in the active layer to the first electrode layer, blocks holes, and suppresses charge recombination, thereby minimizing electrical loss. The charge transport layer may be composed of one or more materials selected from the group consisting of zinc oxide (ZnO), titanium oxide (TiO2), and stenite (SnO2). When such a material is used, it has high conductivity, is optically transparent, and facilitates the movement of particles through low-energy bandgap alignment.

[0029] The active layer above absorbs sunlight to generate electron-hole pairs and may have a donor-acceptor structure. In this case, separation of electrons and holes can occur at the interface between the donor and the acceptor.

[0030] The above donor absorbs sunlight to generate electron-hole pairs (excitons), transfers the generated electrons to the acceptor, and retains the holes to induce charge separation. The above active layer may include PM6 (Poly[(2,6-(4,8-bis(5-(2-ethylhexyl)-4-fluorothiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione))]) as a donor. PM6 is a fluorene-based conjugated polymer, and as it is fluorinated, it has a very broad light absorption spectrum, and by adjusting the band gap, energy alignment with the acceptor can be optimized. The HOMO (Highest Occupied Molecular Orbital) of PM6 can be approximately -5.5 eV, and the LUMO (Lowest Unoccupied Molecular Orbital) can be approximately -3.4 eV. Therefore, the band gap of PM6 is approximately 2.0–2.2 eV.

[0031] The above acceptor collects electrons transferred from the donor, provides an electron transport pathway, and serves to separate electron-hole pairs at the interface formed with the donor. The above active layer may include Y6(2,2'-((2Z,2'Z)-((12,13-bis(2-ethylhexyl)-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2",3":4',5']thieno[2',3':4,5]pyrrolo[3,2-g]thieno[2',3':4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene)dimalononitrile)) as the acceptor. Y6 is a compound with an inherent ADA (Acceptor-Donor-Acceptor) structure, possessing high electron mobility and excellent energy alignment. The HOMO (Highest Occupied Molecular Orbital) of Y6 can be approximately -5.8 eV, and the LUMO (Lowest Unoccupied Molecular Orbital) can be approximately -3.9 eV. Therefore, the band gap of Y6 is approximately 1.8–2.0 eV.

[0032] By utilizing PM6, which has these HOMO-LUMO values, as a donor and Y6 as an acceptor, the HOMO-LUMO values ​​are aligned. The LUMO value of PM6 is aligned to -3.4 eV and the LUMO value of Y6 to -3.9 eV, thereby preventing electrons from flowing in the reverse direction (Y6→PM6) and optimizing the transport path. Additionally, the HOMO value of PM6 is aligned to -5.5 eV and the HOMO value of Y6 to -5.8 eV, thereby preventing holes from flowing in the reverse direction (PM6→Y6) and achieving a hole blocking effect. Therefore, by using PM6 and Y6 as the active layer, recombination losses during the charge generation, separation, and transport processes can be minimized. Consequently, the electron transport path from PM6 to Y6 can be optimized, and the efficiency of the active layer can be maximized.

[0033] The above active layer may comprise a semiconducting single-wall carbon nanotube (SWNT). For example, it may comprise a semiconducting SWNT having (6, 5), (7, 5), (7, 6), (8, 6), (8, 7), (10, 5), (9, 6), (10, 6), and (9, 8) chirality. In particular, the present invention preferably comprises a semiconducting SWNT having (7, 6) or (10, 6) chirality, which has the effect of efficiently interacting with excitons of a specific energy to suppress exciton recombination and improve charge collection efficiency. The (7, 6) or (10, 6) chirality refers to a specific helical structure in which n=7, m=6 or n=10, m=6 in the chiral vector (n, m) of the semiconducting SWNT, and the band gap is approximately 0.7 to 1.0 eV. In the active layer, the semiconducting SWNTs form a one-dimensional conductor network to assist the electron transport pathway, thereby facilitating electron transport and effectively suppressing charge recombination. Additionally, due to the aforementioned band gap, they align well between the donor and the acceptor, spontaneously reinforcing the electron transport pathway. Furthermore, since PM6 is a conjugated polymer capable of π-π bonding and Y6 has an ADA structure strongly influenced by π-π bonding, the electron-rich semiconducting SWNTs can form strong interactions with PM6 and Y6. Preferably, the content of the semiconducting SWNTs in the active layer may be 0.01 to 0.25 ppm.

[0034] The hole transport layer serves to block electrons and selectively transport only the holes generated in the active layer to the second electrode layer. The hole transport layer may be composed of one or more materials selected from the group consisting of MoO3, WO3, V2O5, and CoO4. MoO3 has the advantage of excellent hole transport efficiency and stability; WO3 has excellent high-temperature stability; V2O5 has low contact resistance with the second electrode layer; and Co3O4 has the advantage of excellent chemical stability. Preferably, it is desirable to use MoO3, which has excellent hole transport efficiency and stability.

[0035] The second electrode layer described above is an electrode that transmits holes to an external circuit and substantially collects current and transmits it to the circuit. The second electrode layer may be composed of one or more metals selected from Ag, Au, and Al, and preferably, it is preferable to use Ag, which has high conductivity and reflectivity.

[0036] The organic solar cell according to the present invention has an open circuit voltage (V OC The open circuit voltage (open circuit voltage) may be 0.825 to 0.875V. The open circuit voltage is a voltage measured when the output terminal of the solar cell is open (when current flow is zero), and represents the magnitude of the voltage at which generated electrons can be transferred to an electron collection layer without recombining with holes. Preferably, the open circuit voltage of the organic solar cell may be 0.835 to 0.875V, and more preferably 0.840 to 0.875V. However, since the value of the open circuit voltage of the organic solar cell may change due to various external variables, the present invention is not necessarily limited thereto. For example, the open circuit voltage of the organic solar cell according to the present invention may show a value improved by approximately 0.010 to 0.030V compared to an organic solar cell having an active layer (PM6:Y6) that does not contain semiconducting SWNTs.

[0037] The above organic solar cell has a short-circuit current density (J SC , Short-Circuit Current Density) is 24.00 to 27.00 mA cm -2 It may be. Short-circuit current density refers to the current per unit area generated by a solar cell in a short-circuit state, i.e., when the voltage is zero. The short-circuit current density is an indicator reflecting the efficiency of photogenerated electron and charge transport, and may be influenced by the thickness, bandgap, and electron-hole recombination characteristics of the solar cell. Preferably, the short-circuit current density of the organic solar cell is 24.50 to 27.00 mA cm⁻¹. -2 , more preferably 25.00 to 27.00 mA cm -2 It may be. However, since the short-circuit current density of an organic solar cell can change due to various external variables, the present invention is not necessarily limited thereto. For example, the short-circuit current density of an organic solar cell according to the present invention is about 1.50 to 3.00 mA cm⁻¹ compared to an organic solar cell having an active layer (PM6:Y6) that does not contain semiconducting SWNTs. -2 It can show a value that has improved by approximately [amount].

[0038] The above organic solar cell may have a fill factor (FF) calculated by the following formula 1 to be 55.0 to 60.0%. The fill factor is the maximum power (P) in the voltage-current curve of the solar cell. max It refers to the ratio of the theoretical maximum power calculated as the product of the output, short-circuit current density, and open-circuit voltage. In other words, the fill factor indicates the degree to which the voltage-current curve forms a rectangle. Generally, a higher fill factor of a solar cell means that there is less loss due to internal resistance and that the electrical quality is superior.

[0039] [Formula 1]

[0040]

[0041] (In the above formula 1, FF is the filling rate, P max is the maximum power output, J SC is the short-circuit current density, V OC represents the open-circuit voltage.)

[0042] The above organic solar cell may have a power conversion efficiency (PCE) of 10.00 to 15.00% calculated by the following formula 2.

[0043] [Formula 2]

[0044]

[0045] (In the above formula 2, PCE is the photoelectric conversion efficiency, J SC is the short-circuit current density, V OC is the open-circuit voltage, FF is the fill factor, P in represents the intensity of incident light.)

[0046] At this time, preferably, the photoelectric conversion efficiency of the organic solar cell may be 11.00 to 15.00%, and more preferably 12.00 to 15.00%. However, since the photoelectric conversion efficiency of the organic solar cell may change due to various external variables, the present invention is not necessarily limited thereto. For example, the photoelectric conversion efficiency of the organic solar cell according to the present invention may show a value improved by about 0.5 to 2.0% compared to an organic solar cell having an active layer (PM6:Y6) that does not contain semiconducting SWNTs.

[0047] A method for manufacturing an organic solar cell including the above-mentioned semiconducting SWNT may comprise: A) a step of purifying SWNTs to obtain semiconducting SWNTs; B) a step of forming a first electrode layer on a substrate and washing it; C) a step of applying a first precursor solution and heat-treating it on the first electrode layer to form a charge transport layer; D) a step of applying a second precursor solution on the charge transport layer to form an active layer; E) a step of forming a hole transport layer on the active layer; and F) a step of forming a second electrode layer on the hole transport layer.

[0048] The above step A) may include a) mixing a conjugated polymer in a solvent; b) adding and mixing single-wall carbon nanotubes; c) separating the liquid phase from the mixture; d) removing the solvent from the separated liquid phase; and e) recovering semiconducting single-wall carbon nanotubes.

[0049] Step a) above is a step of preparing a base solution for selectively dispersing SWNTs by mixing a conjugated polymer with a solvent. The conjugated polymer may include “poly(9,9-di-n-dodecylfluorenyl-2,7-diyl) (PFDD)” or “(Poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(9,9-bis(6'-N,N,N-trimethylammonium)hexylfluorenyl-2,7-diyl dibromide)]) (PFO-Bpy)”, and interacts with the semiconducting fraction of the SWNTs to provide a stable dispersion state.

[0050] PFDD is a polymer composed of repeating fluorene structures formed by aromatic rings. Consequently, PFDD forms a uniformly electron-conjugated π-electron system within the mixture, and the strong interaction between this π-electron system and the semiconducting SWNTs maintains a stable dispersion state within the mixture. In this process, the π-electron system has almost no interaction with metallic SWNTs, which have high electron density and mobility, while forming stable bonds with semiconducting SWNTs, which have relatively low electron density and mobility and are prone to energy matching. Therefore, PFDD can selectively disperse semiconducting SWNTs in the liquid phase of the mixture, while metallic SWNTs remain in the solid phase as such dispersion is impossible. Furthermore, PFDD prevents aggregation by coating the semiconducting SWNTs and maintains a stable state in the liquid phase through interactions between PFDD, the semiconducting SWNTs, and the solvent.

[0051] In addition, PFDD dissolves well in solvents with non-polar or weak polarity, has excellent thermal stability, and forms a uniform dispersion state that does not aggregate well even with physical shock or environmental changes.

[0052] PFO-Bpy is also a fluorene-based conjugated polymer with an amphiphilic structure possessing both a hydrophilic domain composed of trimethylammonium groups and a hydrophobic domain composed of octyl chains, and contains bromide ions (Br) that neutralize cations. -PFO-Bpy has an acceptor-donor structure and forms a uniformly electron-conjugated π-electron system, and the π-electron system and the semiconducting SWNT interact strongly to maintain a stable dispersion state within the mixture. Furthermore, it is more suitable for separating specific chiral SWNTs, e.g., SWNTs having (7, 6) or (10, 6) chirality, thereby increasing the short-circuit current density and open-circuit voltage of the organic solar cell according to the present invention.

[0053] The above solvent may include one or more selected from toluene, decalin, tetralin, m-xylene, p-xylene, tetrahydrofuran (THF), chlorobenzene, mesitylene, and cumene, and these solvents have nonpolar or weak polarity, which promotes the interaction between SWNTs and PFDD and facilitates the separation of metallic SWNTs and semiconducting SWNTs. In particular, the present invention preferably uses decalin, tetralin, and m-xylene.

[0054] Decalin, tetralin, and m-xylene are non-polar or weakly polar solvents that mix well with the hydrophobic polymer PFDD, allowing the solvent and the conjugated polymer to form a stable solution. Additionally, the hydrophobic portion of PFDD interacts hydrophobically with the solvent, which enables stable interaction with semiconducting SWNTs.

[0055] Decalin is a dicyclic non-aromatic hydrocarbon with high viscosity and a high boiling point of approximately 190°C, which allows it to stably dissolve PFDD and maintain interactions with SWNTs for a long time. As a non-aromatic substance, decalin is not subject to resonance or hyperconjugation effects; however, as a completely non-polar, hydrophobic material, it can promote interactions between the hydrophobic regions of PFDD and SWNTs. Furthermore, while decalin is non-aromatic and thus free from resonance effects, it possesses high chemical stability and enables stable hydrophobic interactions without electronic interference from specific aromatic polymers during the dissolution process with PFDD.

[0056] Tetralin is a partially hydrogenated naphthalene-based aromatic compound in which one benzene ring is combined with one non-aromatic ring. In other words, Tetralin possesses both aromatic and non-aromatic properties, which can be advantageous in the interaction between PFDD and SWNT. The aromatic ring forms π-π interactions with the fluorene ring of PFDD, helping the conjugated polymer dissolve well in the solvent, while the non-aromatic ring strengthens hydrophobic interactions between SWNT and PFDD, thereby enhancing dispersion stability. Furthermore, by possessing both of these opposing characteristics, Tetralin can be used as a balanced solvent capable of simultaneously supporting both π-π interactions and hydrophobic interactions. Therefore, Tetralin can function as a stable solvent despite having a lower viscosity than decalin.

[0057] In addition, the aforementioned decalin and tetralin have high molecular stability due to their two-ring structure and can withstand various temperatures and physical conditions.

[0058] m-xylene is an aromatic hydrocarbon characterized by two methyl groups bonded to the meta position of a benzene ring, forming strong π-π interactions with PFDD. Additionally, as a solvent that undergoes both resonance and hyperconjugation effects, π-π interactions can be formed particularly strongly.

[0059] In step a) above, the mixing ratio of the conjugated polymer and the solvent can be adjusted to 1 mg:0.5 to 1.5 mL, and this ratio ensures complete dissolution of the polymer and stable dispersion of the SWNTs.

[0060] In step b) above, SWNTs are added to the mixture of the conjugated polymer and the solvent and mixed, and the ratio of SWNTs to the mixture may be 1 mL: 0.5 to 1.5 mg. This ratio enables selective dispersion by ensuring that PFDD is uniformly adsorbed onto the surface of the semiconducting SWNTs; if the ratio is lower than this, the separation efficiency may decrease, and if the ratio is higher, aggregation of the semiconducting SWNTs may occur. Mixing is performed at 35 to 50°C, and this temperature range is intended to maximize the interaction between the conjugated polymer and the SWNTs to selectively disperse the semiconducting SWNTs in the solution and allow the metallic SWNTs to remain in the solid state. In particular, SWNTs manufactured using a plasma torch method may be used. After the mixing step is completed, the semiconducting SWNTs are dissolved and dispersed in the supernatant, while the metallic SWNTs remain in the solid state without dissolving.

[0061] In step c) above, the mixture is centrifuged to separate the metallic SWNTs and the semiconducting SWNTs. The metallic SWNTs precipitate into a solid phase and are separated as a precipitate, while the semiconducting SWNTs dissolve in the supernatant and remain. Therefore, it is necessary to obtain the supernatant by performing centrifugation to separate the solid phase from the supernatant. The centrifugation conditions can be performed at 20,000 to 60,000 g, and the total time required can be 30 minutes to 2 hours. The supernatant separated therefrom consists of a composite of semiconducting SWNTs, PFDD, and a solvent.

[0062] In step d) above, the solvent is removed from the recovered supernatant to concentrate the semiconducting SWNTs. Solvent removal can be performed using low-temperature evaporation or vacuum evaporation techniques, which effectively remove the solvent while maintaining the dispersion characteristics of the SWNTs. Low-temperature or vacuum evaporation techniques are suitable for high-boiling point solvents such as decalin, tetralin, and m-xylene, which maintain the thermal stability of the semiconducting SWNTs to prevent degradation of their properties and prevent chemical structural damage to the PFDD. Therefore, the residue after solvent removal can consist of a composite of PFDD and semiconducting SWNTs. Additionally, since the solvent recovered in this process contains few impurities, a recovery process may be further included with reuse in mind.

[0063] In step e) above, the residue is recovered after solvent removal and washed with ethanol or water to remove PFDD and the residual solvent. After washing, the recovered semiconducting SWNT is finally obtained through filtration and drying steps. The purity of the semiconducting SWNT obtained in this step can be 90% or higher.

[0064] In particular, the semiconducting SWNT obtained in the present invention may be a semiconducting SWNT having (7, 6) or (10, 6) chirality. The semiconducting SWNT having (7, 6) or (10, 6) chirality may be obtained in an amount of about 0.0025 to 0.0075 mg per 1 ml of mixture based on the time before solvent removal.

[0065] Step B) above is a step of forming a base structure of a solar cell and depositing a first electrode layer on a substrate. The substrate may be a transparent material such as glass or plastic (PET (polyethylene terephthalate) or PEN (polyethylene naphthalate)). In this case, ITO (Indium Tin Oxide), FTO (Fluorine-doped Tin Oxide), etc. may be deposited by sputtering or chemical vapor deposition.

[0066] Step C) above is a step for improving electron transport efficiency by forming a charge transport layer, wherein a solution containing nanoparticles such as ZnO, TiO2, and SnO2 is used as the first precursor solution, and the solvent may be a polar solvent such as isopropanol, ethanol, or water. In addition, the first precursor solution may be applied using spin coating, drop coating, or blade coating, and subsequently, the solvent may be evaporated by controlling the temperature to 80 to 150°C to form a thin film, and additionally, the temperature may be controlled to 200 to 400°C to induce crystallization of the nanoparticles.

[0067] Step D) above is a step of forming an active layer including a donor, an acceptor, and a semiconducting SWNT. At this time, the second precursor solution includes PM6, Y6, and semiconducting SWNT, and chlorobenzene, mesitylene, or THF, etc., may be used as a solvent. A uniform film can be formed by applying the second precursor solution using spin coating, drop coating, or blade coating, etc. At this time, the solvent can be removed by controlling the temperature to 60 to 100°C, and the structural stability of the active layer film can be ensured.

[0068] Step E) above is a step of forming a hole transport layer on the active layer, which may involve applying a metal oxide such as MoO3, WO3, V2O5, and CoO4 by vacuum deposition.

[0069] Step F) above is a step of forming a second electrode layer that transmits holes to an external circuit, and it is preferable to form a uniform thin film of one or more metals selected from Ag, Au, and Al by vacuum deposition or sputtering.

[0070] Hereinafter, an organic solar cell comprising a semiconducting SWNT according to the present invention and a method for manufacturing the same will be described in more detail through examples. However, the following examples are merely references for explaining the present invention in detail, and the present invention is not limited thereto and can be implemented in various forms.

[0071] Furthermore, unless otherwise defined, all technical and scientific terms have the same meaning as generally understood by one of the art to which the present invention pertains. The terms used in the description herein are merely for the purpose of effectively describing specific embodiments and are not intended to limit the present invention. Additionally, the units of additives not specifically stated in the specification may be in weight percent.

[0072] [Example 1]

[0073] PFDD was mixed with toluene at a ratio of 1 mg:1 mL, and then the mixture was mixed with SWNT at a ratio of 1 mL:1 mg. The mixture was dispersed for 2 hours while maintaining the temperature at 40–45°C. The dispersed mixture was subjected to a separation process in a centrifuge at 40,000 g for 1 hour, and the supernatant was recovered. Subsequently, the remaining PFDD was removed by filtering, and a solution was prepared in which semiconducting SWNTs wrapped around a polymer were dispersed in chloronaphthalene.

[0074] An ITO-coated glass substrate was washed three times in an ultrasonic device using acetone, distilled water, and isopropanol in that order, and the washed substrate was treated with UV-ozone for 30 minutes.

[0075] Next, a solution containing diethyl zinc:THF in a 1:2 ratio was dropped onto the first electrode layer (ITO), spin-coated at 4,000 rpm for 40 seconds, and the spin-coated layer was heat-treated at 200°C to prepare a charge transport layer.

[0076] A solution in which semiconducting SWNTs wrapped around the polymer were dispersed in a solution of PM6:Y6 dissolved in chloroform was added to a concentration of 0.5 vol.%, the solution was dropped onto the charge transport layer, and an active layer was prepared by spin-coating at 2,000 rpm for 50 seconds.

[0077] Subsequently, a hole transport layer was prepared by depositing MoO3 to a thickness of 13 nm on the active layer, and then Ag was deposited to a thickness of 100 nm on the hole transport layer.

[0078] [Example 2]

[0079] All procedures were performed identically to Example 1, except that PFO-Bpy was used instead of PFDD as the conjugated polymer.

[0080] [Comparative Example]

[0081] All processes were performed identically to Example 1, except that simple SWNTs were used instead of semiconducting SWNTs.

[0082] [Characteristic Evaluation Method]

[0083] A. Confirmation of separation of semiconducting SWNTs

[0084] Figure 1 shows the UV-Vis absorption spectra according to the conjugated polymer used for the separation of semiconducting SWNTs. It can be seen that semiconducting SWNTs with (10, 6) chirality were well separated when PFO-Bpy was used, and semiconducting SWNTs with (7, 6) chirality were well separated when PFDD was used. At this time, characteristic peaks can be observed at approximately 1402 nm for semiconducting SWNTs with (10, 6) chirality and at 1134 nm for semiconducting SWNTs with (7, 6) chirality.

[0085] B. Performance Evaluation of Organic Solar Cells

[0086] The open-circuit voltage, short-circuit current, fill factor, and photoelectric conversion efficiency of the organic solar cell were measured.

[0087] Open circuit voltage (V) Short-circuit current density (mA cm⁻¹) -2 ) Filling Rate (%) Photoelectric Conversion Efficiency (%) Comparative Example 0.8 26 23.0 8 55 9.1 1 1.3 Example 10.8 44 25.5 37 58.5 1 2.6 Example 20.8 46 25.4 7 35 6.2 1 2.1

[0088] The open-circuit voltage was 0.826 V for the comparative example, and 0.844 V and 0.846 V for Examples 1 and 2 using semiconducting SWNTs, respectively, confirming that the open-circuit voltage of the examples is higher than that of the comparative example. In other words, it can be confirmed that the voltage at which electrons generated in the examples can be transferred to the electron collection layer without recombining with holes is greater than that of the comparative example. The short-circuit current density was 23.085 mA cm⁻¹ for the comparative example. -2 Examples 1 and 2 using semiconducting SWNTs each showed 25.537 mA cm⁻¹ -2 , 25.473mA cm -2As shown, it can be confirmed that the short-circuit current density of the example is higher than that of the comparative example. In other words, compared to the comparative example, it can be confirmed that the current per unit area generated in the example is greater in the short-circuit state, i.e., when the voltage is 0, and that the efficiency of photogenerated electron and charge transport is higher.

[0089] The filling rate was 59.1% for the comparative example, and 58.5% and 56.2% for Examples 1 and 2, respectively, showing a slightly higher tendency for the comparative example.

[0090] The photoelectric conversion efficiency was 11.3% for the comparative example, and 12.6% and 12.1% for Examples 1 and 2, respectively, confirming that the photoelectric conversion efficiency of the examples is higher than that of the comparative example.

[0091] Although the present invention has been described above through specific details and limited embodiments, this is provided merely to aid in the overall understanding of the invention, and the invention is not limited to the above embodiments. Those skilled in the art can make various modifications and variations from this description.

[0092] Accordingly, the scope of the present invention is not limited to the described embodiments, and all things equivalent to or having equivalent variations to the claims set forth below, as well as the claims set forth below, shall be considered to fall within the scope of the concept of the present invention.

Claims

1. Substrate; A first electrode layer formed on the above substrate; A charge transport layer formed on the first electrode layer; An active layer formed on the above charge transport layer; A hole transport layer formed on the above active layer and A second electrode layer formed on the above hole transport layer; Includes, An organic solar cell comprising a single-wall carbon nanotube (SWNT), characterized in that the active layer comprises a single-wall carbon nanotube.

2. In Paragraph 1, An organic solar cell comprising one or more semiconducting SWNTs selected from the group consisting of ITO (Indium Tin Oxide), FTO (Fluorine-doped Tin Oxide), AZO (Aluminum-doped Zinc Oxide), and GZO (Gallium-doped Zinc Oxide) for the first electrode layer.

3. In Paragraph 1, An organic solar cell comprising a semiconducting SWNT, wherein the charge transport layer is composed of one or more selected from the group consisting of zinc oxide (ZnO), titanium oxide (TiO2), and stenite (SnO2).

4. In Paragraph 1, The above active layer is an organic solar cell comprising a semiconducting SWNT having a donor-acceptor structure.

5. In Paragraph 4, An organic solar cell comprising a semiconducting SWNT in which the active layer comprises PM6(Poly[(2,6-(4,8-bis(5-(2-ethylhexyl)-4-fluorothiophen-2-yl)benzo[1,2-b:4,5-b']dithiophene))-alt-(5,5-(1',3'-di-2-thienyl-5',7'-bis(2-ethylhexyl)benzo[1',2'-c:4',5'-c']dithiophene-4,8-dione))]) as a donor.

6. In Paragraph 4, An organic solar cell comprising a semiconducting SWNT in which the active layer comprises Y6(2,2'-((2Z,2'Z)-((12,13-bis(2-ethylhexyl)-12,13-dihydro-[1,2,5]thiadiazolo[3,4-e]thieno[2",3":4',5']thieno[2',3':4,5]pyrrolo[3,2-g]thieno[2',3':4,5]thieno[3,2-b]indole-2,10-diyl)bis(methanylylidene))bis(5,6-difluoro-3-oxo-2,3-dihydro-1H-indene-2,1-diylidene)dimalononitrile)) as an acceptor.

7. In Paragraph 1, An organic solar cell comprising a semiconducting SWNT in which the hole transport layer is composed of one or more selected from the group consisting of MoO3, WO3, V2O5, and CoO4. 8.A) A step of purifying SWNTs to obtain semiconducting SWNTs; B) A step of forming a first electrode layer on a substrate and cleaning it; C) A step of forming a charge transport layer by applying and heat-treating a first precursor solution onto the first electrode layer; D) A step of forming an active layer by applying a second precursor solution onto the charge transport layer; E) a step of forming a hole transport layer on the active layer; and F) A step of forming a second electrode layer on the hole transport layer above; Includes, A method for manufacturing an organic solar cell comprising semiconductor SWNTs, wherein the second precursor solution comprises PM6, Y6, and semiconductor SWNTs.

9. In Paragraph 8, Step A) above is, a) A step of mixing the conjugated polymer in a solvent; b) A step of adding and mixing single-wall carbon nanotubes; c) Step of separating the liquid phase from the mixture; d) a step of removing the solvent from the separated liquid phase; and e) a step of recovering semiconducting single-walled carbon nanotubes; A method for manufacturing an organic solar cell comprising a semiconducting SWNT that includes 10. In Paragraph 9, A method for manufacturing an organic solar cell comprising a semiconducting SWNT, wherein the conjugated polymer comprises one or more selected from PFDD (Poly(9,9-di-n-dodecylfluorenyl-2,7-diyl)) or PFO-Bpy (Poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(9,9-bis(6'-N,N,N-trimethylammonium)hexylfluorenyl-2,7-diyl dibromide)]).

11. In Paragraph 9, A method for manufacturing an organic solar cell comprising a semiconducting SWNT, wherein the solvent comprises one or more selected from toluene, decalin, tetralin, m-xylene, p-xylene, tetrahydrofuran (THF), chlorobenzene, mesitylene, and cumene.

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