KR20220037609A - Quantum dots solar cell having excellent photo-stability and preparing method of the same - Google Patents

Abstract

A quantum dot solar cell is provided. The quantum dot solar cell includes: a transparent substrate; a charge transport layer formed on the transparent substrate; a photoactive layer formed on the charge transport layer; a hole transport layer formed on the photoactive layer; and an electrode formed on the hole transport layer. The charge transport layer includes quantum dots that selectively block high-energy photons. The photoactive layer includes an organic material.

Description

QUANTUM DOTS SOLAR CELL HAVING EXCELLENT PHOTO-STABILITY AND PREPARING METHOD OF THE SAME

The present application relates to a quantum dot solar cell with improved photostability and a method for manufacturing the same.

A photovoltaic cell, that is, a solar cell, is a device that converts infinite solar energy into electrical energy, and as an eco-friendly next-generation energy source, a lot of research and development is being conducted in terms of alternative energy development. Such solar cells can be largely divided into solar cells using inorganic materials such as silicon and solar cells using organic materials. Among them, solar cells using inorganic compound semiconductors such as silicon or gallium arsenide (GaAs) have various advantages. Nevertheless, there is a big disadvantage that there is a limit to commercialization due to the high price compared to the performance.

As an alternative to overcome these shortcomings, organic solar cells have been proposed. The organic solar cell uses a p-type or n-type organic semiconductor material as a photoactive layer, and due to its simple device structure, the manufacturing process is simple and modularization is easy, the energy loss between the unit device and the module is small, and the extinction coefficient is high, making it thin and thin. Not only does it have the advantage of being able to absorb more than 50% of light even in a thin film, but it also has the advantage of being able to cut costs significantly compared to inorganic solar cells because it can ultimately be manufactured based on a solution process. In addition, organic solar cells are currently reported to have excellent photoelectric conversion efficiency of 10% or more.

In spite of the above-described advantages, organic solar cells have very weak stability to light, which has problems such as long-term stability and short lifespan of the device, which is the biggest obstacle to commercialization of organic solar cells.

In order to solve the above-mentioned long-term stability problem of organic solar cells, various research and development are being made on light absorbing materials used for photoactive layers, intermediate layers for charge transfer, and electrode materials. Since it has not been done, development for it is required.

Republic of Korea Patent Publication No. 19969918, which is the background technology of the present application, relates to an organic solar cell with improved photostability and a method for manufacturing the same, and more particularly, to an organic solar cell with significantly improved photostability through introduction of an intermediate layer. However, the registered patent does not mention a quantum dot solar cell including quantum dots in which the charge transport layer selectively blocks high energy photons.

The present application provides a quantum dot solar cell with improved photostability and a method for manufacturing the same in order to solve the problems of the prior art described above.

However, the technical problems to be achieved by the embodiments of the present application are not limited to the technical problems described above, and other technical problems may exist.

As a technical means for achieving the above technical problem, the first aspect of the present application, a transparent substrate; a charge transport layer formed on the transparent substrate; a photoactive layer formed on the charge transport layer; a hole transport layer formed on the photoactive layer; and an electrode formed on the hole transport layer, wherein the charge transport layer includes quantum dots that selectively block high-energy photons, and the photoactive layer includes an organic material, providing a quantum dot solar cell do.

According to one embodiment of the present application, the high-energy photon may have a wavelength in the range of 300 nm to 400 nm, but is not limited thereto.

According to the exemplary embodiment of the present application, the quantum dot may have a bandgap in the range of 0.8 eV to 1.7 eV, but is not limited thereto.

According to one embodiment of the present application, the quantum dots are indium arsenide (InAs), indium phosphide (InP), lead sulfide (PbS), indium antimonide (InSb), gallium arsenide (GaAs), gallium phosphide (GaP), antimonide gallium (GaSb), cadmium selenide (CdSe), cadmium sulfide (CdS), cadmium telluride (CdTe), zinc selenide (ZnSe), zinc telluride (ZnTe), and combinations thereof It may include, but is not limited to.

According to one embodiment of the present application, the carrier concentration of the quantum dots may be 10 ¹⁶ cm ^-3 to 10 ¹⁷ cm ^-3 , but is not limited thereto.

According to one embodiment of the present application, the quantum dots may form an n-layer, but is not limited thereto.

According to one embodiment of the present application, the quantum dots may include an exposed surface in a specific direction, and a ligand may be bound to the exposed surface, but is not limited thereto.

According to one embodiment of the present application, the quantum dots may have different energy levels depending on the ratio of the exposed surface or the amount of the ligand, but is not limited thereto.

According to the exemplary embodiment of the present application, the energy level of the quantum dot may be controlled by a difference in electronegativity between the exposed surface and the ligand, but is not limited thereto.

According to the exemplary embodiment of the present application, the charge transport layer may further include a metal oxide, but is not limited thereto.

According to one embodiment of the present application, the metal oxide is TiO ₂ , NiO _x , Zn ₂ SnO ₄ , ZnO, ZrO, Al ₂ O ₃ , SnO ₂ , WO ₃ , Nb ₂ O ₅ , TiSrO ₃ and combinations thereof It may include one selected from the group consisting of, but is not limited thereto.

According to one embodiment of the present application, the transparent substrate is selected from the group consisting of ITO, FTO, IZO, ZnO-Ga ₂ O ₃ , ZnO-Al ₂ O ₃ , SnO ₂ -Sb ₂ O ₃ and combinations thereof. It may include, but is not limited to.

According to one embodiment of the present application, the photoactive layer may include a bulk heterojunction (BHJ) layer, but is not limited thereto.

According to one embodiment of the present application, the hole transport layer is MoO ₃ , Spiro-OMeTAD, PEDOT:PSS, G-PEDOT, PANI:PSS, PANI:CSA, PDBT, P3HT, PCPDTBT, PCDTBT, PTAA, V ₂ O ₅ , NiO, WO ₃ , CuI, CuSCN, and may include one selected from the group consisting of combinations thereof, but is not limited thereto.

According to one embodiment of the present application, the electrode is selected from the group consisting of Ag, Au, Pt, Ni, Cu, In, Ru, Pd, Rh, Mo, Ir, Os, C, a conductive polymer, and combinations thereof. It may include, but is not limited to.

A second aspect of the present application, the method comprising: forming a charge transport layer on a transparent substrate; forming a photoactive layer on the charge transport layer; forming a hole transport layer on the photoactive layer; and forming an electrode on the hole transport layer, wherein the charge transport layer includes quantum dots that selectively block high-energy photons, and the photoactive layer includes an organic material, quantum dot solar A method for manufacturing a battery is provided.

According to one embodiment of the present application, the high-energy photon may have a wavelength in the range of 300 nm to 400 nm, but is not limited thereto.

According to the exemplary embodiment of the present application, the quantum dot may have a bandgap in the range of 0.8 eV to 1.7 eV, but is not limited thereto.

According to one embodiment of the present application, the step of forming the charge transport layer and the photoactive layer is spin coating, drop casting, dip coating, bar coating, inkjet printing, nozzle printing, spray coating, slot die coating, gravure printing, screen printing , electrohydrodynamic jet printing, electrospray, and may be performed by a method selected from the group consisting of combinations thereof, but is not limited thereto.

According to one embodiment of the present application, the step of forming the hole transport layer is physical vapor deposition (Physical Vapor Deposition, PVD), sputtering (sputtering), RF / DC sputtering, atomic layer deposition (Atomic Layer Deposition, ALD), electron beam deposition (Electron-beam Evaporation), ion beam sputtering, Chemical Vapor Deposition (CVD), low pressure chemical vapor deposition (LPCVD), plasma chemical vapor deposition (PECVD), ion plating and combinations thereof. It may be performed by a method selected from the group consisting of, but is not limited thereto.

The above-described problem solving means are merely exemplary, and should not be construed as limiting the present application. In addition to the exemplary embodiments described above, additional embodiments may exist in the drawings and detailed description.

The quantum dot solar cell according to the present application provides a quantum dot solar cell with significantly improved photostability and efficiency compared to a conventional organic solar cell by including a quantum dot that selectively blocks high-energy photons in a charge transport layer.

Conventional organic solar cells have high photoelectric conversion efficiency, but by using an organic-based photoactive layer material, the stability of the device is reduced in a short period of time due to high-energy light. Since metal oxides such as ₂ have a relatively large bandgap to block high-energy light, there is a limitation in that they cannot block high-energy light in the charge transport layer through which light enters. On the other hand, the quantum dot solar cell according to the present application includes quantum dots having a band gap in a range where the charge transport layer selectively blocks high energy photons, thereby blocking high energy light to provide a quantum dot solar cell with significantly improved photostability. there is.

In addition, since metal oxides such as ZnO and TiO ₂ , which are conventional charge transport layer materials, have depleted oxygen defects and have photocatalytic properties, there was a problem in promoting the decomposition of the organic photoactive layer, but the quantum dot solar cell according to the present application By introducing a new charge transport layer without photocatalytic properties, it is possible to provide a quantum dot solar cell with significantly improved photostability by fundamentally blocking the decomposition of the organic photoactive layer.

In addition, the quantum dot solar cell according to the present application protects the light absorbing material of the organic photoactive layer vulnerable to active oxygen by blocking direct contact with active oxygen without an external protective film by introducing a new charge transport layer without photocatalytic properties, thereby improving photostability. It is possible to provide a remarkably improved quantum dot solar cell.

In addition, the quantum dot solar cell according to the present application can provide a quantum dot solar cell with significantly improved photoelectric conversion efficiency by forming a highly conductive n-layer with quantum dots having excellent charge transport ability and introducing it as a material of the charge transport layer.

In addition, the manufacturing method of the quantum dot solar cell according to the present application can form a large-area thin film uniformly by forming the charge transport layer and the photoactive layer using a solution process.

In addition, the manufacturing method of the quantum dot solar cell according to the present application has the advantage that it can be applied to a large area and a flexible device by using a method of spin coating on a substrate with a liquefied sample.

In addition, the manufacturing method of the quantum dot solar cell according to the present application uses a method of spin coating on a substrate with a liquefied sample, so it is easy to enlarge the area and the process is simple. and economical efficiency.

In addition, the method for manufacturing a quantum dot solar cell according to the present application has an advantage in that a high-quality thin film with few defects can be obtained because the hole transport layer is formed using physical vapor deposition, so that it is deposited in a high vacuum.

However, the effects obtainable herein are not limited to the above-described effects, and other effects may exist.

1 is a schematic diagram of a quantum dot solar cell according to an embodiment of the present application.
2 is a schematic diagram showing the operating principle of a quantum dot solar cell according to an embodiment of the present application.
3 is a flowchart illustrating a method of manufacturing a quantum dot solar cell according to an embodiment of the present application.
4 is a graph showing normalized power conversion efficiency (PCE) measured over time for driving stability of solar cells according to Examples and Comparative Examples of the present application.
5 is a graph showing absorption spectra of solar cells according to Examples and Comparative Examples of the present application.
6 is a graph showing a comparison result of current-voltage curves of solar cells according to Examples and Comparative Examples of the present application.
7 is a graph measuring the photoelectric conversion efficiency and driving stability according to the thickness of the quantum dot thin film of the quantum dot solar cell manufactured according to the embodiment of the present application.
8 is a graph showing the results of analyzing the degree of decomposition of the organic photoactive layer according to the amount of irradiation light of the solar cells according to Examples and Comparative Examples of the present application through changes in the absorbance of the organic photoactive layer.
9 is a graph showing a result of predicting a transmission path of sunlight within a device through optical simulation according to the structure of a solar cell according to Examples and Comparative Examples of the present application.

Hereinafter, embodiments of the present application will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art to which the present application pertains can easily carry out. However, the present application may be implemented in several different forms and is not limited to the embodiments described herein. And in order to clearly explain the present application in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout this specification, when a part is "connected" with another part, this includes not only the case where it is "directly connected" but also the case where it is "electrically connected" with another element interposed therebetween. do.

Throughout this specification, when a member is positioned “on”, “on”, “on”, “on”, “under”, “under”, or “under” another member, this means that a member is positioned on the other member. It includes not only the case where they are in contact, but also the case where another member exists between two members.

Throughout this specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

As used herein, the terms "about," "substantially," and the like are used in a sense at or close to the numerical value when the manufacturing and material tolerances inherent in the stated meaning are presented, and to aid in the understanding of the present application. It is used to prevent an unconscionable infringer from using the mentioned disclosure in an unreasonable way. Also, throughout this specification, "step to" or "step to" does not mean "step for".

Throughout this specification, the term "combination of these" included in the expression of the Markush form means one or more mixtures or combinations selected from the group consisting of the components described in the expression of the Markush form, and the components It is meant to include one or more selected from the group consisting of.

Throughout this specification, reference to “A and/or B” means “A, B, or A and B”.

Hereinafter, a quantum dot solar cell with improved photostability of the present application and a manufacturing method thereof will be described in detail with reference to embodiments, examples, and drawings. However, the present application is not limited to these embodiments and examples and drawings.

As a technical means for achieving the above technical problem, the first aspect of the present application, the transparent substrate 100; a charge transport layer 200 formed on the transparent substrate 100; a photoactive layer 300 formed on the charge transport layer 200; a hole transport layer 400 formed on the photoactive layer 300; And in the quantum dot solar cell comprising an electrode 500 formed on the hole transport layer 400, the charge transport layer 200 includes quantum dots that selectively block high energy photons, the photoactive layer 300 is It provides a quantum dot solar cell comprising an organic material.

1 is a schematic diagram of a quantum dot solar cell according to an embodiment of the present application, and FIG. 2 is a schematic diagram showing an operating principle of a quantum dot solar cell according to an embodiment of the present application.

Organic solar cells have very weak stability to light, which has problems such as long-term stability and short lifespan of the device, which is the biggest obstacle to the commercialization of organic solar cells.

The quantum dot solar cell according to the present application includes quantum dots in which the charge transport layer 200 selectively blocks high-energy photons, thereby providing a quantum dot solar cell with significantly improved photostability and efficiency compared to conventional organic solar cells. there is.

According to one embodiment of the present application, the high-energy photon may have a wavelength in the range of about 300 nm to about 400 nm, but is not limited thereto.

According to one embodiment of the present application, the quantum dots may have a bandgap in the range of about 0.8 eV to about 1.7 eV, but is not limited thereto.

Conventional organic solar cells have high photoelectric conversion efficiency, but by using the organic-based photoactive layer 300 material, there is a limitation in that the stability of the device is deteriorated in a short period of time due to high energy light.

Since the conventional metal oxide charge transport layer 200 has a relatively large bandgap to block high energy light, high energy having a wavelength in the range of about 300 nm to about 400 nm passes through the charge transport layer 200 and is photoactive. By reaching the layer 300 , there is a problem in that the organic material of the photoactive layer 300 is decomposed and the photoelectric conversion efficiency of the photoactive layer 300 falls in a short period of time.

The quantum dot solar cell according to the present application comprises quantum dots having a bandgap in the range of about 0.8 eV to about 1.7 eV in which the charge transport layer 200 selectively blocks high energy photons having a wavelength in the range of about 300 nm to about 400 nm. , there is an advantage in that it is possible to provide a quantum dot solar cell with significantly improved photostability by blocking high-energy light.

According to one embodiment of the present application, the quantum dots are indium arsenide (InAs), indium phosphide (InP), lead sulfide (PbS), indium antimonide (InSb), gallium arsenide (GaAs), gallium phosphide (GaP), antimonide gallium (GaSb), cadmium selenide (CdSe), cadmium sulfide (CdS), cadmium telluride (CdTe), zinc selenide (ZnSe), zinc telluride (ZnTe), and combinations thereof It may include, but is not limited to.

For example, the quantum dot may be indium arsenide, but is not limited thereto.

As the size of the material is reduced to the nano level, the electrical and optical properties are greatly changed. Such semiconductor particles are called quantum dots (QDs). Specifically, the wavelength and frequency of light that can be emitted and absorbed can be efficiently controlled by forming quantum dots by controlling the size of particles rather than changing the type of material.

However, referring to Formula 1 below, in order to block light (3.1 eV to 4.1 eV) in the wavelength range of 300 nm to 400 nm, because the band gap is inevitably improved when the compound in the bulk state is made into quantum dots, the bulk state The bandgap must be less than 3.1 eV. For example, since the bandgap of bulk InAs is 0.4 eV and that of bulk ZnO is 3.4 eV, a narrow bandgap cannot be formed even if the quantum confinement effect according to Formula 1 is applied, and high energy photons cannot be selectively blocked . Therefore, it is very important that the quantum dots have a bandgap in the range of about 0.8 eV to about 1.7 eV that selectively blocks high-energy photons having a wavelength in the range of about 300 nm to about 400 nm.

[Formula 1]

(In Formula 1, R is the radius of the quantum dot, m _r is the effective mass, E _g (NC) is the band gap of the quantum dot, E _g (bulk) is the band gap in the bulk state, ħ is the Planck constant)

Referring to Formula 1, in general, the energy band gap of the quantum dot state is improved compared to that of the bulk state. Accordingly, quantum dot materials having a bandgap in the range of about 0.8 eV to about 1.7 eV that selectively block high-energy photons having a wavelength in the range of about 300 nm to about 400 nm in the quantum dot state are greatly limited.

In addition, metal oxides such as ZnO and TiO ₂ , which are materials of the conventional charge transport layer 200, have a depleted oxygen defect and have photocatalytic properties, so there is a problem in promoting the decomposition of the organic photoactive layer 300, By introducing a new charge transport layer 200 without photocatalytic properties, the quantum dot solar cell according to there is.

In addition, the quantum dot solar cell according to the present application introduces a new charge transport layer 200 without photocatalytic properties, thereby blocking direct contact with active oxygen without an external protective film, thereby absorbing material of the organic photoactive layer 300 vulnerable to active oxygen It is possible to provide a quantum dot solar cell with significantly improved photostability by protecting it.

According to one embodiment of the present application, the carrier concentration of the quantum dots may be from about 10 ¹⁶ cm ^-3 to about 10 ¹⁷ cm ^-3 , but is not limited thereto.

In general, doped semiconductors in silicon semiconductors have carrier concentrations in the range of 10 ¹⁰ cm ^-3 to 10 ¹⁸ cm ^-3 . The quantum dot solar cell according to the present application has a carrier concentration of about 10 ¹⁶ cm ^-3 to about 10 ¹⁷ cm ^-3 , and as a semiconductor (charge transport layer) that has been sufficiently doped, has the advantage of enabling smooth electron transfer.

According to one embodiment of the present application, the quantum dots may form an n-layer, but is not limited thereto.

The quantum dot solar cell according to the present application forms a high conductivity n-layer with quantum dots having excellent charge transport ability and introduces it as a material of the charge transport layer 200, thereby providing a quantum dot solar cell with significantly improved photoelectric conversion efficiency.

According to one embodiment of the present application, the quantum dots may include an exposed surface in a specific direction, and a ligand may be bound to the exposed surface, but is not limited thereto.

According to one embodiment of the present application, the quantum dots may have different energy levels depending on the ratio of the exposed surface or the amount of the ligand, but is not limited thereto.

Specifically, by controlling the ratio of the exposed surface in the specific direction, it is possible to control the amount of the ligand bound to the exposed surface. For example, in the case of indium phosphide (InP), the (111) surface has a facet exposed only with indium (In). Since the indium is stabilized by binding to the anionic ligand, the (111) side may be well attached to the ligand. On the other hand, the (110) plane is the surface on which indium-phosphorus (In-P) is exposed, and the exposed unsaturated bond of In-P can stabilize the surface through self passivation, and the ligand does not adhere well. create an environment Using these properties, the amount of ligand attached to the surface can be controlled depending on whether the surface in a specific direction is exposed.

According to the exemplary embodiment of the present application, the energy level of the quantum dot may be controlled by a difference in electronegativity between the exposed surface and the ligand, but is not limited thereto.

As described above, it is very important that the quantum dots have a bandgap in the range of about 0.8 eV to about 1.7 eV that selectively blocks high-energy photons having a wavelength in the range of about 300 nm to about 400 nm.

The quantum dot solar cell according to the present application can control the energy level of the quantum dot by using the difference in electronegativity between the exposed surface of the quantum dot in a specific direction and the ligand bound to the exposed surface in the specific direction.

In particular, by controlling the ratio of the exposed surface in the specific direction, it is possible to control the amount of the ligand bound to the exposed surface.

The ligand exchange reaction through the control of the ratio of the exposed surface in the specific direction can control the type and amount of binding ligand according to the exposed surface in the specific direction, so that the energy level of the material can be finely adjusted.

Accordingly, there is an advantage in that a quantum dot solar cell with improved photostability and photoelectric conversion efficiency can be provided by using the quantum dot with the adjusted energy level as the charge transport layer 200 .

According to the exemplary embodiment of the present application, the charge transport layer 200 may further include a metal oxide, but is not limited thereto.

According to one embodiment of the present application, the metal oxide is TiO ₂ , NiO _x , Zn ₂ SnO ₄ , ZnO, ZrO, Al ₂ O ₃ , SnO ₂ , WO ₃ , Nb ₂ O ₅ , TiSrO ₃ and combinations thereof It may include one selected from the group consisting of, but is not limited thereto.

According to the exemplary embodiment of the present application, the transparent substrate 100 is a group consisting of ITO, FTO, IZO, ZnO-Ga ₂ O ₃ , ZnO-Al ₂ O ₃ , SnO ₂ -Sb ₂ O ₃ and combinations thereof. It may include one selected from, but is not limited thereto.

For example, the transparent substrate 100 may be ITO, which is a highly conductive semiconductor material having excellent light transmittance while serving as an electrode, but is not limited thereto.

The transparent substrate 100 may include a conductive material, and may serve as a substrate for the electrode 500 on the quantum dot solar cell according to the present disclosure.

According to one embodiment of the present application, the photoactive layer 300 may include a bulk heterojunction (BHJ) layer, but is not limited thereto.

The bulk heterojunction structure is a structure in which a donor material and an acceptor material are mixed with a size of several tens of nm or less. In such a bulk heterojunction structure, since the donor/acceptor interface area is significantly larger than that of the PN bilayer structure, charge-separation efficiency can be increased as much as that, and as a result, the photoelectric conversion efficiency can be improved. .

For example, the photoactive layer 300 may include P3HT:PCBM in which poly-3 (hexylthiophene) (P3HT) and phenyl-C61-butyric acid methyl ester (PCBM) are mixed, but is not limited thereto.

According to the exemplary embodiment of the present application, the hole transport layer 400 is MoO ₃ , Spiro-OMeTAD, PEDOT:PSS, G-PEDOT, PANI:PSS, PANI:CSA, PDBT, P3HT, PCPDTBT, PCDTBT, PTAA, V ₂ O ₅ , NiO, WO ₃ , CuI, CuSCN, and may include one selected from the group consisting of combinations thereof, but is not limited thereto.

For example, the hole transport layer 400 may include MoO ₃ , but is not limited thereto.

When the hole transport layer 400 includes MoO ₃ which is a metal oxide having a low energy level, there is a good advantage in combining the energy level with Ag as the upper electrode.

According to one embodiment of the present application, the electrode 500 is a group consisting of Ag, Au, Pt, Ni, Cu, In, Ru, Pd, Rh, Mo, Ir, Os, C, a conductive polymer, and combinations thereof. It may include one selected from, but is not limited thereto.

For example, the electrode 500 may be Ag, but is not limited thereto. When Ag is used as the electrode 500, there is an advantage of being stable in an external environment and having high conductivity.

In addition, the quantum dot solar cell according to the present application is basically an organic material-based solar cell including an organic material-based photoactive layer 300 , and may have flexible characteristics. Therefore, there is an advantage that such a solar cell can be used by attaching it to a separate flexible substrate.

3 is a flowchart illustrating a method of manufacturing a quantum dot solar cell according to an embodiment of the present application.

A second aspect of the present application, forming a charge transport layer 200 on the transparent substrate 100; forming a photoactive layer 300 on the charge transport layer 200; forming a hole transport layer 400 on the photoactive layer 300; and forming an electrode 500 on the hole transport layer 400, wherein the charge transport layer 200 includes quantum dots that selectively block high-energy photons, and the photoactive layer ( 300) provides a method for manufacturing a quantum dot solar cell, which includes an organic material.

With respect to the method of manufacturing a quantum dot solar cell according to the second aspect of the present application, detailed descriptions of parts overlapping with the first aspect of the present application are omitted, but even if the description is omitted, the contents described in the first aspect of the present application The same can be applied to the second aspect.

According to one embodiment of the present application, the high-energy photon may have a wavelength in the range of about 300 nm to about 400 nm, but is not limited thereto.

According to one embodiment of the present application, the quantum dots may have a bandgap in the range of about 0.8 eV to about 1.7 eV, but is not limited thereto.

First, the charge transport layer 200 is formed on the transparent substrate 100 (S100).

The manufacturing method of the quantum dot solar cell according to the present application can form a large-area thin film uniformly and quickly by forming the charge transport layer 200 and the photoactive layer 300 using a solution process.

According to one embodiment of the present application, the step of forming the charge transport layer 200 and the photoactive layer 300 is spin coating, drop casting, dip coating, bar coating, inkjet printing, nozzle printing, spray coating, slot die coating , gravure printing, screen printing, electrohydrodynamic jet printing, electrospray, and may be performed by a method selected from the group consisting of combinations thereof, but is not limited thereto.

For example, the charge transport layer 200 may be formed by a spin coating method, but is not limited thereto.

The manufacturing method of the quantum dot solar cell according to the present application has the advantage of being applicable to a large area and a flexible device by using a method of spin coating on a substrate with a liquefied sample.

In addition, the manufacturing method of the quantum dot solar cell according to the present application uses a method of spin coating on a substrate with a liquefied sample, so it is easy to enlarge the area and the process is simple. and economical efficiency.

Then, the photoactive layer 300 is formed on the charge transport layer 200 (S200).

The manufacturing method of the quantum dot solar cell according to the present application has an advantage in that the photoactive layer 300 solution is spin-coated on the sample, so that it can be evenly stacked on the lower layer.

Next, the hole transport layer 400 is formed on the photoactive layer 300 (S300).

According to one embodiment of the present application, the step of forming the hole transport layer 400 is physical vapor deposition (Physical Vapor Deposition, PVD), sputtering (sputtering), RF / DC sputtering, atomic layer deposition (Atomic Layer Deposition, ALD) , Electron-beam Evaporation, Ion Beam Sputtering, Chemical Vapor Deposition (CVD), Low Pressure Chemical Vapor Deposition (LPCVD), Plasma Chemical Vapor Deposition (PECVD), ion plating, and their It may be performed by a method selected from the group consisting of combinations, but is not limited thereto.

For example, the hole transport layer 400 may be formed by a physical vapor deposition method, but is not limited thereto.

The manufacturing method of the quantum dot solar cell according to the present application has the advantage of obtaining a high-quality thin film with few defects because the hole transport layer 400 is deposited in a high vacuum.

Next, an electrode 500 is formed on the hole transport layer 400 (S400).

The present invention will be described in more detail through the following examples, but the following examples are for illustrative purposes only and are not intended to limit the scope of the present application.

[Example] Preparation of quantum dot solar cell (ITO/InAs QD/BHJ/MoO ₃ /Ag)

After nucleation by reacting the In precursor and the As precursor at a high temperature, InAs quantum dots (QDs) were synthesized by growing them to a desired size.

Then, a solution of the InAs quantum dot was prepared by treating the InAs quantum dot with a ligand.

Then, the InAs quantum dot solution was spin-coated on the ITO thin film-coated substrate, and then heat-treated to form a uniform and defect-free charge transport layer.

Then, the photoactive layer BHJ solution was spin-coated and then heat-treated to form crystals.

Then, a MoO ₃ hole transport layer and an Ag electrode were sequentially stacked using a physical vapor deposition equipment to prepare a quantum dot solar cell (ITO/InAs QD/BHJ/MoO ₃ /Ag).

[Comparative Example] Preparation of solar cells (ITO/ZnO/BHJ/MoO ₃ /Ag)

A ZnO solution was spin-coated on the ITO thin film-coated substrate, and then heat-treated to form a ZnO charge transport layer.

Then, the photoactive layer BHJ solution was spin-coated and then heat-treated to form crystals.

Then, a MoO ₃ hole transport layer and an Ag electrode were sequentially stacked using a physical vapor deposition equipment to prepare a solar cell (ITO/ZnO/BHJ/MoO ₃ /Ag).

[Experimental Example 1]

4 is a graph showing normalized power conversion efficiency (PCE) measured over time for driving stability of solar cells according to Examples and Comparative Examples of the present application.

Specifically, the solar cells according to Examples and Comparative Examples of the present application were irradiated with continuous sunlight (AM 1.5 G, 100 mW/cm ² ) in the ITO direction using a solar simulator equipment. After light irradiation, the efficiency of the solar cell was measured every 15 minutes to evaluate the performance.

Through this, the quantum dot solar cell according to the embodiment of the present application maintains an efficiency of 90% or more of the initial photoelectric conversion efficiency when exposed for 15 to 60 minutes under sunlight (AM 1.5G, 100 mW/cm ² ). could confirm that In the case of the solar cell according to the comparative example using the metal oxide as the charge transport layer 200, the initial photoelectric conversion efficiency when exposed for 15 to 60 minutes under sunlight (AM 1.5G, 100 mW/cm ² ) is 20 It can be confirmed that only about % is maintained, and through this, it can be confirmed that the quantum dot solar cell according to the embodiment of the present application exhibits very good photostability.

This is because, in the case of the comparative example, since ZnO having a relatively large bandgap to block high energy light is used as the charge transport layer, high energy light cannot be blocked in the charge transport layer through which light enters, whereas the quantum dot solar cell according to the present application is This suggests that the InAs quantum dot charge transport layer significantly improves photostability by selectively blocking high-energy photons.

[Experimental Example 2]

5 is a graph showing absorption spectra of solar cells according to Examples and Comparative Examples of the present application.

Specifically, in the case of (A) of FIG. 5 , a thin film identical to that of an actual solar cell was fabricated with the photoactive layer on a glass substrate, and absorbance was measured using UV-vis-NIR spectroscopy. In the case of (B) of FIG. 5 , a thin film of the charge transport layer was fabricated on a glass substrate in the same manner as in an actual solar cell, and absorbance was measured using UV-vis-NIR spectroscopy. The background of the graph shows the spectrum according to the wavelength of sunlight.

Through this, it was confirmed that the InAs charge transport layer according to the embodiment of the present application absorbs and blocks high energy photons in the range of 300 nm to 400 nm. On the other hand, in the case of the comparative example, it was confirmed that high energy photons in the range of 300 nm to 400 nm could not be blocked.

[Experimental Example 3]

6A is a graph showing the energy levels of the ZnO electron transport layer, the InAs charge transport layer, and the BHJ photoactive layer according to Examples and Comparative Examples of the present application.

Through this, it was confirmed that the energy level values of ZnO and InAs were close to those of BHJ. This means smooth electron transfer.

Figure 6 (B) is a current density (Current Density) graph with respect to voltage for each of the solar cells according to Examples and Comparative Examples of the present application, Figure 6 (C) is a graph according to Examples and Comparative Examples of the present application This is a table showing comparison of open-circuit voltage (Voc), short-circuit current (Jsc), fill factor (FF), and power conversion efficiency (PCE) for each solar cell.

Specifically, current-voltage curves were measured using a solar simulator by driving the solar cells according to Examples and Comparative Examples of the present application, respectively.

Through this, it could be confirmed that the photoelectric conversion efficiency of the solar cell was comparable to that of the ZnO solar cell because the InAs solar cell had no problem in the role of the charge transport layer even when high energy was blocked.

[Experimental Example 4]

7 is a graph measuring the photoelectric conversion efficiency and driving stability according to the thickness of the quantum dot thin film of the quantum dot solar cell manufactured according to the embodiment of the present application.

Specifically, a solar cell was manufactured while increasing and decreasing the thickness by controlling the concentration of InAs, and the efficiency was measured using a solar simulator (yellow). In addition, the ratio of the maintained efficiency compared to the initial efficiency after 2 hours of light irradiation using a solar simulator is also shown (green).

Through this, it was confirmed that as the thickness of InAs was increased, the role of blocking high-energy light was increased and the photostability was improved. Accordingly, it could be confirmed that a solar cell having high efficiency and stability at the optimum InAs thickness was fabricated.

[Experimental Example 5]

8 is a graph showing the results of analyzing the degree of decomposition of the organic photoactive layer according to the amount of irradiation light of the solar cells according to Examples and Comparative Examples of the present application through changes in the absorbance of the organic photoactive layer.

Specifically, (A) of FIG. 8 is a graph showing the absorbance. A thin film identical to that of an actual solar cell was fabricated on the photoactive layer on a glass substrate, and absorbance was measured using UV-vis-NIR spectroscopy. Then, the absorbance was measured again after irradiating sunlight for 30 minutes and 60 minutes, respectively, using a solar simulator.

Through this, it was confirmed that the photoactive layer loses its intrinsic properties due to light when there is no quantum dot that blocks light, and thus the performance is greatly reduced.

(B) of FIG. 8 is a photoactive layer stacked on the electron transport layer of the solar cell according to the Examples and Comparative Examples of the present application, each with an actual thickness (original) used in the solar cell and a thin thickness (thin) that can see the interfacial effect Then, it is a graph showing how much is maintained compared to the initial level by measuring the absorbance after 30 minutes and 60 minutes of light irradiation with a solar simulator, respectively.

Through this, since ZnO, which is the charge transport layer of the solar cell according to the comparative example of the present application, does not play a role of blocking high energy light, the absorbance of the photoactive layer decreases significantly as the light irradiation time increases, whereas the It was confirmed that the absorption of the photoactive layer was maintained by InAs, which is the charge transport layer of the solar cell, as a high-energy light blocking layer.

[Experimental Example 6]

9 is a graph showing a result of predicting a transmission path of sunlight within a device through optical simulation according to the structure of a solar cell according to Examples and Comparative Examples of the present application.

Specifically, optical information of ZnO and InAs, ITO, BHJ, Ag, which are charge transport layers of the solar cell according to the Examples and Comparative Examples of the present application, is input through the transfer matrix method (TMM) optical simulation, and when light is irradiated, light How it is transmitted and absorbed is calculated and shown.

Referring to FIG. 9A , in the ZnO solar cell according to the comparative example of the present application, there was no absorption at a short wavelength, so the light intensity fraction indicating the degree of absorption was low, and it was confirmed that the portion absorbed by the BHJ was large.

On the other hand, referring to FIG. 9B , it was confirmed that the InAs solar cell according to the embodiment of the present application absorbs a lot of light at a short wavelength, and the intensity that BHJ absorbs in the short wavelength region is reduced.

The above description of the present application is for illustration, and those of ordinary skill in the art to which the present application pertains will understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present application. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a dispersed form, and likewise components described as distributed may also be implemented in a combined form.

The scope of the present application is indicated by the following claims rather than the above detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present application.

100: transparent substrate
200: charge transport layer
300: photoactive layer
400: hole transport layer
500: electrode

Claims (20)

transparent substrate;
a charge transport layer formed on the transparent substrate;
a photoactive layer formed on the charge transport layer;
a hole transport layer formed on the photoactive layer; and
an electrode formed on the hole transport layer;
In the quantum dot solar cell comprising a,
The charge transport layer includes quantum dots that selectively block high-energy photons,
The photoactive layer will include an organic material,
Quantum dot solar cells.
The method of claim 1,
The high-energy photon will have a wavelength in the range of 300 nm to 400 nm, a quantum dot solar cell.
The method of claim 1,
The quantum dot will have a bandgap in the range of 0.8 eV to 1.7 eV, a quantum dot solar cell.
The method of claim 1,
The quantum dots are indium arsenide (InAs), indium phosphide (InP), lead sulfide (PbS), indium antimonide (InSb), gallium arsenide (GaAs), gallium phosphide (GaP), gallium antimonide (GaSb), cadmium selenide (CdSe), cadmium sulfide (CdS), cadmium telluride (CdTe), zinc selenide (ZnSe), zinc telluride (ZnTe), and a quantum dot solar cell comprising one selected from the group consisting of combinations thereof .
The method of claim 1,
The quantum dot carrier concentration is 10 ¹⁶ cm ^-3 to 10 ¹⁷ cm ^-3 , the quantum dot solar cell.
The method of claim 1,
The quantum dot will form an n-layer, quantum dot solar cell.
The method of claim 1,
The quantum dots include an exposed surface in a specific direction,
The ligand is bound to the exposed surface, quantum dot solar cell.
8. The method of claim 7,
The quantum dot will have a different energy level depending on the ratio of the exposed surface or the amount of the ligand, the quantum dot solar cell.
8. The method of claim 7,
In the quantum dot, the energy level is controlled by the difference in electronegativity between the exposed surface and the ligand, a quantum dot solar cell.
The method of claim 1,
The charge transport layer will further include a metal oxide, quantum dot solar cell.
11. The method of claim 10,
wherein the metal oxide is selected from the group consisting of TiO ₂ , NiO _x , Zn ₂ SnO ₄ , ZnO, ZrO, Al ₂ O ₃ , SnO ₂ , WO ₃ , Nb ₂ O ₅ , TiSrO ₃ and combinations thereof. Quantum dot solar cell.
The method of claim 1,
Wherein the transparent substrate is selected from the group consisting of ITO, FTO, IZO, ZnO-Ga ₂ O ₃ , ZnO-Al ₂ O ₃ , SnO ₂ -Sb ₂ O ₃ and combinations thereof, quantum dot solar battery.
The method of claim 1,
The photoactive layer is a quantum dot solar cell comprising a bulk heterojunction (BHJ) layer.
2. The method of claim 1
The hole transport layer is MoO ₃ , Spiro-OMeTAD, PEDOT:PSS, G-PEDOT, PANI:PSS, PANI:CSA, PDBT, P3HT, PCPDTBT, PCDTBT, PTAA, V ₂ O ₅ , NiO, WO ₃ , CuI, CuSCN And, which includes those selected from the group consisting of combinations thereof, quantum dot solar cells.
The method of claim 1,
The electrode is a quantum dot aspect, including one selected from the group consisting of Ag, Au, Pt, Ni, Cu, In, Ru, Pd, Rh, Mo, Ir, Os, C, conductive polymers and combinations thereof battery.
forming a charge transport layer on the transparent substrate;
forming a photoactive layer on the charge transport layer;
forming a hole transport layer on the photoactive layer; and
forming an electrode on the hole transport layer;
In a quantum dot solar cell comprising a,
The charge transport layer includes quantum dots that selectively block high-energy photons,
The photoactive layer will include an organic material,
A method for manufacturing a quantum dot solar cell.
17. The method of claim 16,
The high-energy photon has a wavelength in the range of 300 nm to 400 nm, the method of manufacturing a quantum dot solar cell.
17. The method of claim 16,
The quantum dot will have a bandgap in the range of 0.8 eV to 1.7 eV, a method of manufacturing a quantum dot solar cell.
17. The method of claim 16,
The step of forming the charge transport layer and the photoactive layer is spin coating, drop casting, dip coating, bar coating, inkjet printing, nozzle printing, spray coating, slot die coating, gravure printing, screen printing, electrohydrodynamic jet printing, electricity A method of manufacturing a quantum dot solar cell, which is performed by a method selected from the group consisting of spraying and combinations thereof.
17. The method of claim 16,
Forming the hole transport layer is physical vapor deposition (Physical Vapor Deposition, PVD), sputtering (sputtering), RF / DC sputtering, atomic layer deposition (Atomic Layer Deposition, ALD), electron-beam deposition (Electron-beam Evaporation), ion beam By a method selected from the group consisting of sputtering, chemical vapor deposition (CVD), low pressure chemical vapor deposition (LPCVD), plasma chemical vapor deposition (PECVD), ion plating, and combinations thereof A method of manufacturing a quantum dot solar cell that is performed.

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