KR102113536B1 - Semitransparent organic photovoltaics module - Google Patents

Abstract

The present invention relates to a semi-transparent organic solar cell having the performance of an organic solar cell and having a high light transmittance even if the upper electrode, that is, a metal electrode, which caused a decrease in the conventional light transmittance, is excluded.

Description

Semi-transparent organic solar cell module {SEMITRANSPARENT ORGANIC PHOTOVOLTAICS MODULE}

The present invention relates to a translucent organic solar cell module.

 In general, a solar cell is a photovoltaic cell manufactured for the purpose of converting solar energy into electrical energy, and means a semiconductor device that converts light energy generated from the sun into electrical energy. Such solar cells are expected to be an energy source that can solve future energy problems due to low pollution, infinite resources, and semi-permanent life.

In recent years, research on low-cost solar cells that lowers the cost of power generation and research on high-efficiency solar cells that increase conversion efficiency are being conducted simultaneously.

The solar cell may be divided into an inorganic solar cell and an organic solar cell according to the material constituting the photoactive layer among the internal constituent materials.

Inorganic solar cells use inorganic materials, mainly monocrystalline silicon. These monocrystalline silicon-based solar cells are excellent in terms of efficiency and stability, and occupy most of the solar cells currently being mass-produced, but currently secure raw materials, light weight, flexible, high efficiency and low price. It is limiting the development of Japanese technology.

On the other hand, organic solar cells use organic materials such as small molecule (also expressed as single molecule) or polymer organic semiconductor materials, so they are significantly cheaper than inorganic materials used in inorganic solar cells and have various synthetic and It is possible to process and improve productivity. In addition, since it proceeds to a solution-based process at a relatively low temperature compared to other semiconductor technologies, it is possible to simplify, speed up and enlarge the manufacturing process. In particular, research has been actively conducted on organic solar cells having advantages that can be applied to various substrates such as low-cost glass or plastic, which may be a problem during high-temperature treatment.

1 is a cross-sectional view showing a unit cell structure of a conventional organic solar cell.

Existing organic solar cells 50, on the substrate 10, the lower electrode (11,21), electron transport layer (12,22), photoactive layer (13,23), hole transport layer (14,24) and the upper electrode ( 15,25) have a stacked structure. Generally, the lower electrodes 11 and 21 are cathodes, and the upper electrodes 15 and 25 are anodes.

Each unit cell is electrically connected, but has a structure in which the upper electrode 15 of the cell 1 is energized with the lower electrode 21 of the cell 2.

The upper electrodes 15 and 25 of the organic solar cell 50 having the structure shown in FIG. 1 use metal electrodes. That is, it is prepared by applying and drying using a silver (Ag) paste. When a metal material such as silver is used as the upper electrodes 15 and 25, an organic solar cell 50 having a light transmittance of 0% is usually manufactured.

Recently, as interest in a building integrated photovoltaic (BIPV) system has increased, research is being conducted to use windows as well as exterior walls of buildings as organic solar cells. In order to use an organic solar cell as an exterior or window of a building, a portion of light must be transmitted, so a semi-transparent organic solar cell having a light transmittance of a certain level or higher is used.

However, when the metal material is used as the upper electrodes 15 and 25, light transmittance cannot be secured at all.

Accordingly, various methods for improving transparency of organic solar cells have been studied.

As an example, Korean Patent Publication No. 2009-0111725 discloses a transparent organic thin film solar cell capable of controlling light transmittance according to the thickness of an electrode in an organic thin film solar cell including a lower electrode, an electron transport layer, a photoactive layer, and an upper electrode. Doing.

In addition, Korean Patent Publication No. 2015-0036342 discloses a method of improving the permeability of an organic solar cell by specifying a composition and thickness of each layer and different deposition methods in which the upper electrode is made of a multi-layer structure. It is disclosed.

These patents have improved the transparency of the organic solar cell to some extent, but the effect is not sufficient and a lot of time and cost are required due to process changes or additions.

Therefore, it is necessary to further develop a translucent organic solar cell having excellent performance through a simple process.

Republic of Korea Patent Publication No. 2009-0111725 (2009.10.27), transparent organic thin film solar cell Republic of Korea Patent Publication No. 2015-0036342 (2015.04.07), a transparent electrode for optoelectronic devices

As a result, the present inventors conducted various studies to solve the above-mentioned problems, and as a result, formed a highly conductive hole transport layer on the photoactive layer to enable driving of the battery without installing a top electrode such as conventional Ag, and at the same time, the light of the battery. The present invention was completed by confirming that it is possible to increase the efficiency of the battery without increasing the resistance by securing the transmittance and replacing the electrical connection between the unit cells formed of the upper electrode with the auxiliary electrode.

Accordingly, an object of the present invention is to provide a translucent organic solar cell having a light transmittance of a certain level or more.

In order to achieve the above object, the present invention is a substrate; And In the organic solar cell module having a plurality of unit cells formed on the substrate,

The unit cell includes a lower electrode, an electron transport layer, a photoactive layer, and a hole transport layer including a hole transport material and a conductive nanowire,

A semi-transparent organic solar cell module having an auxiliary electrode in an area between unit cells is provided for electrical connection between the unit cells.

At this time, the auxiliary electrode includes an electrically conductive oxide including ITO, SnO ₂ , In ₂ O ₃ , ZnO, and MgZnO; Electrically conductive nitrides including TiN, CrN, InGaN, GaN, InN, AlGaN and AlInGaN; Contains one or more metals including Au, Ag, Pt, Cu, Ni, Fe, Pd, Rh, Ir, Co, Sn, Zn and Mo.

In addition, the hole transport layer is characterized in that the conductive nanowires form a three-dimensional network structure in the matrix containing the hole transport material.

The semi-transparent organic solar cell according to the present invention is capable of driving a cell even when the upper electrode is excluded, and improves resistance between unit cells, thereby improving the performance and life of the organic solar cell.

In addition, the organic solar cell is easy to apply to the roll-to-roll process, which enables the production of large-sized organic solar cells as well as small-sized organic solar cells.

1 is a cross-sectional view showing a unit cell structure of a conventional translucent organic solar cell.
2 is a cross-sectional view showing a unit cell structure of a translucent organic solar cell according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains may easily practice. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. In addition, the same reference numbers in the drawings refer to the same components, and the size or thickness of each component may be exaggerated for convenience of description.

When a member is referred to as being “on” another member in the present specification, this includes not only the case where one member is in contact with the other member but also another member between the two members.

When a part is referred to as “comprising” a certain component in the present specification, it means that the component may further include other components, not to exclude other components, unless there is a specifically opposed substrate.

A conventional organic solar cell is formed using a metal paste as an upper electrode, and the light transmittance (ie, light transmittance or visible light transmittance) of the organic solar cell is reduced due to the metal electrode made of the metal paste. Accordingly, a configuration excluding the upper metal electrode has been proposed. However, since the upper electrode performs the electrical connection function between unit cells at the same time, it is impossible to implement the electrical connection due to the exclusion of the upper electrode. Accordingly, an electrical connection between unit cells was attempted by using a hole transport layer, which is a configuration of the top layer of the organic solar cell, but series resistance between unit cells was significantly increased, resulting in current loss of the organic solar cell.

Specifically, in the case of manufacturing an organic solar cell using a slot die process, each unit cell is disposed at intervals of a predetermined distance to separate. At this time, the unit cell has a voltage characteristic of about 0.8V, and the unit cells are electrically connected to control the number and arrangement of them to control the output voltage of the finally obtained organic solar cell.

The electrical connection of the unit cells is usually made through the extension of the upper electrode as shown in FIG. 1. At this time, in the case of a structure other than the upper electrode, another layer (eg, a hole transport layer) should perform its role, but the existing hole transport layer does not have a sufficient level of electrical conductivity for electrical connection. Due to this, the series resistance between unit cells is greatly increased, and as a result, current loss of the organic solar cell occurs. Therefore, the upper electrode must be made of an essential configuration, but it is not easy to implement a semi-transparent organic solar cell due to a decrease in light transmittance due to use of the upper electrode.

Accordingly, in the present invention, a semi-transparent organic solar cell is realized by securing a light transmittance (or transparency, transparency) of a certain level or more, but a semi-transparent structure having a new structure capable of lowering the series resistance between unit cells even if the upper electrode is excluded to secure the light transmittance Present an organic solar cell.

Specifically, the translucent organic solar cell according to the present invention changes the composition of the hole transport layer so as not to use the upper electrode made of a metal material that lowers the light transmittance, and introduces an auxiliary electrode for lowering the series resistance due to electrical connection between unit cells. It has a structure.

2 is a cross-sectional view showing a unit cell structure of a translucent organic solar cell according to an embodiment of the present invention.

Referring to FIG. 2, in a unit cell of a semi-transparent organic solar cell, lower electrodes 101 and 201 are positioned on a substrate 100, and electron transport layers 102 and 202, photoactive layers 103 and 203, and hole transport layers 104 and 204 are sequentially located thereon. It is laminated, and has a structure excluding the upper electrode.

Each of the unit cells (Cell 1, Cell 2) is formed at a predetermined distance apart, wherein the unit cells are electrically connected through the auxiliary electrodes (301,302). Specifically, the lower electrode 201 of the other unit cell (Cell 2) adjacent to the hole transport layer 104 of one unit cell (Cell 1) is electrically connected through the auxiliary electrode 301.

The auxiliary electrodes 301 and 302 may be any material as long as the material has high electrical conductivity.

For example, electrically conductive oxides such as ITO, SnO ₂ , In ₂ O ₃ , ZnO, or MgZnO; Electrically conductive nitrides such as TiN, CrN, InGaN, GaN, InN, AlGaN, or AlInGaN; Metals such as Au, Ag, Pt, Cu, Ni, Fe, Pd, Rh, Ir, Co, Sn, Zn and Mo can be used. The electrically conductive oxide and the electrically conductive nitride have an advantage of having high light transmittance, and the metal has an advantage of excellent electrical conductivity, and each of them can be used or used in combination.

Preferably, when the electrical conductivity is low, since the resistance between the unit cells is increased, the efficiency of the translucent organic solar cell module may be lowered, so a metal material is used to reduce the series resistance between the unit cells due to the high electrical conductivity, and most preferably Use silver.

The auxiliary electrodes 301 and 302 include one side surface of the unit cell Cell 1, and are formed to include a part of the lower electrode 201 of the neighboring unit cell Cell 2.

If necessary, the auxiliary electrodes 301 and 302 may have a multi-layer structure of two or more layers, and may be used in the form of an alloy or a mixture of two or more types.

In addition, the present invention, in order to ensure a structure excluding the upper electrode, it is preferable to form a hole transport layer (104,204) having a high conductivity so that it can simultaneously serve as the upper electrode and the hole transport layer.

Specifically, the hole transport layers 104 and 204 according to the present invention include a hole transport material and a conductive nanowire.

Since conductive nanowires are used instead of the metal paste for forming the existing anode, the problem due to the solvent and impurities contained in the paste does not occur, so that the life of the organic solar cell can be increased. In addition, since the conductive nanowires and the hole transport material are dispersed in the solution phase, the coating method can be used as well as the roll-to-roll process.

The hole transport layers 104 and 204 of the present invention have the advantage of being capable of thinning a semi-transparent organic solar cell and reducing the number of laminations in terms of process because it simultaneously functions as an anode and a conventional hole transport layer.

In addition, the hole transport layers 104 and 204 form a three-dimensional network structure of conductive nanowires in a matrix including a hole transport material, so that they are connected to each other, so that the movement of holes becomes smoother, and thus photoelectric conversion of translucent organic solar cells Efficiency can be improved.

The hole transport material is used for the generation and delivery of holes, a polymer; Organic compounds; One or more selected from the group consisting of minerals is possible.

Specifically, polymers for hole transport include poly (3,4-ethylenedioxythiophene) (PEDOT), poly (styrenesulfonate) (PSS), polyaniline, phthalocyanine, pentacene, polydiphenyl acetylene, and poly (t- Butyl) diphenylacetylene, poly (trifluoromethyl) diphenylacetylene, copper phthalocyanine (Cu-PC) poly (bistrifluoromethyl) acetylene, polybis (T-butyldiphenyl) acetylene, poly (trimethylsilyl) Diphenylacetylene, poly (carbazole) diphenylacetylene, polydiacetylene, polyphenylacetylene, polypyridineacetylene, polymethoxyphenylacetylene, polymethylphenylacetylene, poly (t-butyl) phenylacetylene, polynitrophenylacetylene, poly (Trifluoromethyl) phenylacetylene, poly (trimethylsilyl) phenylacetylene, derivatives thereof, and combinations thereof, and may include any one of the hole transport materials selected from the group, preferably of the PEDOT and PSS Mixtures.

In addition, the organic compound for hole transport is NPB (4,4'-bis (N-phenyl-1-naphthylamino) biphenyl, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] bi Phenyl); TPD (N, N'-Bis (3-methylphenyl) -N, N'-diphenylbenzidine, N, N'-bis (3-methylphenyl) -N, N'-diphenylbenzidine), MTDATA (4,4 ', 4 "-Tris [phenyl (m-tolyl) amino] triphenylamine, 4,4 ', 4" -tris [(3-methylphenyl) phenylamino] triphenylamine), TAPC (4,4'-Cyclohexylidenebis [N, N -bis (4-methylphenyl) benzenamine], 4,4'-cyclohexylidene bis [N, N-bis (4-methylphenyl) benzeneamyl]), TCTA (Tris (4-carbazoyl-9-ylphenyl) amine, Tris (4-carbazoyl-9-ylphenyl) amine), CBP (4,4'-Bis (N-carbazolyl) -1,1'-biphenyl, 4,4'-bis (N-carbazolyl) -1 , 1'-biphenyl), Alq3, mCP (9,9 '-(1,3-Phenylene) bis-9H-carbazol, 9,9'-(1,3-phenylene) bis-9H-carbazole) And 2-TNATA (4,4 ', 4 "-Tris [2-naphthyl (phenyl) amino] triphenylamine, 4,4', 4" -tris (N- (2-naphthyl) -N-phenylamino) tri Phenylamine).

In addition, inorganic materials for hole transport include MoO ₃ , MoO ₂ , WO ₃ , V ₂ O ₅ , ReO ₃ , NiO, Mo (tfd) ₃ , HAT-CN (Hexaazatriphenylenehexacarbonitrile, hexaazatriphenylene hexacarbonitrile) and F4 -TCNQ (7,7,8,8-Tetracyano-2,3,5,6-tetrafluoroquinodimethane, 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane) One or more selected from the group consisting of is possible, and preferably uses MoO ₃ .

The conductive nanowire serves as an anode of the organic solar cell and may include one or more selected from the group consisting of metal-based nanowires and carbon-based nanowires.

As the metal-based nanowires that can be used in the present invention, conventional metal-based nanowires can be used without particular limitation. For example, the metal-based nanowire may be made of at least one metal element selected from the group consisting of Au, Ag, Pt, Cu, Ni, Fe, Pd, Rh, Ir, Co, Sn, Zn and Mo, preferably May be made of silver (Ag).

Carbon-based nanowires that can be used in the present invention may include one or more selected from the group consisting of carbon nanotubes, carbon nanofibers, and graphene, and preferably carbon nanotubes.

The shape of the conductive nanowire is not particularly limited, and may be appropriately selected according to the purpose, and may have any shape such as a columnar shape, a cuboid shape, or a pillar shape having a polygonal cross section.

In addition, the average length of the long axis of the conductive nanowires is 1 µm or more, preferably 5 µm or more, more preferably 10 µm or more, for example, 1 to 1000 µm, and specifically 5 to 100 µm. When the length of the conductive nanowire is less than 1 μm, there is a fear that a junction point decreases between the nanowires, thereby increasing resistance. Further, the shortened average length (diameter) of the conductive nanowire is 1 to 200 nm, preferably 5 to 100 nm, more preferably 10 to 50 nm. If the diameter of the nanowire is too small, there is a fear that the heat resistance of the nanowire is lowered. On the contrary, if the diameter is too large, haze due to scattering increases, and there is a fear that light transmittance and visibility of the hole transport layers 104 and 204 containing conductive nanowires are deteriorated.

The content of the conductive nanowires in the hole transport layers 104 and 204 is not particularly limited, but is not preferably included in a content that is too high for dispersibility and light transmittance. Therefore, the content of the conductive nanowires may be 0.1 to 10% by weight, preferably 1 to 10% by weight. If the content of the conductive nanowire is less than the above range, it cannot function as an electrode, and if it exceeds the above range, the dispersibility and light transmittance are significantly reduced, and the content of the hole transport material (eg, PEDOT: PSS) is relatively low. Since it decreases, this also causes a problem that the photoelectric conversion efficiency decreases, so it is appropriately used within the above range.

The hole transport layers 104 and 204 may have a thickness of 0.1 to 5 μm. In the case of the conventional organic solar cell, the hole transport layer is 0.1 to 10 μm, and the positive electrode is formed to a thickness of 5 to 20 μm. Compared to this, the thickness of the hole transport layers 104 and 204 of the present invention is 0.1 to 5 μm, and preferably 0.1 to 2 μm, so that the thickness of the final translucent organic solar cell can be significantly reduced.

On the other hand, the other configuration of the module of the organic solar cell of the present invention presented in Figure 2 is not particularly limited, and follows the known.

The substrate 100 is not particularly limited and can be used as long as it has transparency.

For example, the substrate 100 is a transparent inorganic substrate such as quartz or glass, or polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), polystyrene (PS), polypropylene (PP), polyyi One transparent selected from the group consisting of mid (PI), polyethylene sulfonate (PES), polyoxymethylene (POM), polyether ether ketone (PEEK), polyether sulfone (PES) and polyetherimide (PEI) Plastic substrates can be used. Among them, it is preferable to use a transparent plastic substrate in the form of a film having flexibility, high chemical stability, mechanical strength, and light transmittance.

Further, it is preferable that the substrate 100 has a light transmittance of at least 70% or more, preferably 80% or more, at a visible light wavelength of about 400 to 750 nm.

The thickness of the substrate 100 is not particularly limited and may be appropriately determined according to a use purpose, and may be, for example, 1 to 500 μm.

The lower electrodes 101 and 201 are cathodes and are formed on the above-described substrate 100.

The lower electrodes 101 and 201 are paths through which the light passing through the substrate 100 can reach the photoactive layers 103 and 203, and thus have a high light transmittance and a conductive material having a high work function of about 4.5 eV or higher and low resistance. It is preferred to use.

For example, the lower electrodes 101 and 201 include indium tin oxide (ITO), indium zinc oxide (IZO), fluorine-doped tin oxide (FTO), and ZnO-Ga. A metal oxide transparent electrode selected from the group consisting of ₂ O ₃ , ZnO-Al ₂ O ₃ , SnO2-Sb ₂ O ₃ and combinations thereof; Organic transparent electrodes such as conductive polymers, graphene thin films, graphene oxide thin films, and carbon nanotube thin films; Alternatively, an organic-inorganic coupling transparent electrode such as a thin film of carbon nanotubes in which metal is combined may be used.

The thickness of the lower electrodes 101 and 201 may be 10 to 3000 nm.

The electron transport layers 102 and 202 are positioned on the lower electrodes 101 and 201 described above, and serve to increase the efficiency of the semi-transparent organic solar cell 500 by increasing electron transport capability. In addition, by blocking oxygen and moisture introduced from the outside it can be prevented from affecting the photoactive layer (104,204).

The electron transport layers 102 and 202 may be formed of a metal oxide and an organic material, and the metal oxide is titanium (Ti), zinc (Zn), silicon (Si), manganese (Mn), strontium (Sr), indium (In), Barium (Ba), potassium (K), niobium (Nb), iron (Fe), tantalum (Ta), tungsten (W), bismuth (Bi), nickel (Ni), copper (Cu), molybdenum (Mo) , Cerium (Ce), platinum (Pt), silver (Ag), and rhodium (Rh). Specifically, the metal oxide thin film layer may be made of zinc oxide (ZnO) having a wide band gap and semiconductive properties, and the organic material may be PEI (polyethyleneimine), PEIE (ethoxylated polyethylenimine), or the like.

In addition, the metal oxide contained in the electron transporting layers 102 and 202 has an average particle diameter of 10 nm or less, specifically 1 to 8 nm, and more specifically 3 to 7 nm.

The electron transport layers 102 and 202 may be formed through coating, and the coating process includes slot die coating, spin coating, spray coating, screen printing, bar coating, doctor blade coating, and gravure printing. Although it can be used, any method that can coat the metal oxide can be used without being limited thereto. In particular, it may be advantageous for the electron transport layers 102 and 202 to use a slot die coating.

The thickness of the electron transport layers 102 and 202 may be 1 to 100 nm, and when the thickness exceeds the prescribed thickness range, electron transport capability may be deteriorated.

The photoactive layers 103 and 203 are positioned on the electron transport layers 102 and 202 described above, and have a bulk heterojunction structure in which a hole acceptor and an electron acceptor are mixed.

The hole acceptor includes an organic semiconductor such as an electrically conductive polymer or an organic low molecular semiconductor material. The electrically conductive polymer may be at least one selected from the group consisting of polythiphene, polyphenylenevinylene, polyfulorene, polypyrrole, and copolymers thereof. The organic low molecular semiconductor material includes at least one selected from the group consisting of pentacene, anthracene, tetracene, perylene, oligothiphene, and derivatives thereof. can do.

Specifically, the hole acceptor is poly-3-hexylthiophene (P3HT), poly-3-octylthiophene (P3OT), polyparaphenylenevinylene (poly-p -phenylenevinylene; PPV), poly (9,9'-dioctylfluorene) (poly (9,9'-dioctylfluorene)), poly (2-methoxy-5- (2-ethyl-hexyloxy) -1 , 4-phenylenevinylene) (poly (2-methoxy-5- (2-ethyl-hexyloxy) -1,4-phenylenevinylene; MEH-PPV) and poly (2-methyl-5- (3 ', 7' -Dimethyloctyloxy))-1,4-phenylenevinylene (poly (2-methyl-5- (3 ', 7'-dimethyloctyloxy))-1,4-phenylene vinylene; MDMOPPV) It may contain one or more.

The electron acceptor may include one or more selected from the group consisting of fullerene derivatives such as fullerene (C60), C70, C76, C78, C80, C82, and C84, CdS, CdSe, CdTe, and ZnSe.

Specifically, the electron acceptor is (6,6) -phenyl-C61-butyric acid methyl ester ((6,6) -phenyl-C61-butyric acid methyl ester; PCBM), (6,6) -phenyl-C71- Butyric acid methyl ester ((6,6) -phenyl-C71-butyric acid methyl ester; C70-PCBM), (6,6) -thienyl-C61-butyric acid methyl ester ((6,6) -thienyl -C61-butyric acid methyl ester; ThCBM) and may include one or more selected from the group consisting of carbon nanotubes.

In this case, the photoactive layers 103 and 203 are more preferably a mixture of P3HT as a hole acceptor and PCBM as an electron acceptor, and the mixing weight ratio of the P3HT and PCBM may be 1: 0.1 to 1: 2.

The thickness of the photoactive layers 103 and 203 may be 10 to 1000 nm, specifically 100 to 500 nm. When the thickness of the photoactive layers 103 and 203 is less than the above range, it is impossible to sufficiently absorb sunlight, and a decrease in efficiency is expected due to a low photocurrent. Conversely, when the above-mentioned range is exceeded, the excited electrons and holes cannot move to the electrode. Degradation problems may occur.

In addition, the semi-transparent organic solar cell 500 of the present invention is between the lower electrode 101,201 and the photoactive layer 103,203 (excluding the electron transport layer), between the lower electrode 101,201 and the electron transport layer 102,202, or A metal oxide thin film layer (not shown) is included between the electron transport layers 102 and 202 and the photoactive layers 103 and 203. The metal oxide thin film layer enables the operation of the organic solar cell 500 by increasing the movement speed of electrons as a secondary electrode, and blocks oxygen and moisture penetrating from the outside so that the polymer contained in the photoactive layers 103 and 203 is oxygen. And it is possible to improve the life of the organic solar cell 500 by preventing deterioration by moisture.

The metal oxide thin film layer may have a thickness of 10 to 500 nm, preferably 20 to 300 nm, and more preferably 20 to 200 nm. When the thickness of the metal oxide thin film layer is within the above range, it is possible to effectively prevent oxygen and moisture from penetrating from the outside and affecting the photoactive layer 40 and the hole transport layer 50 while improving the electron movement speed.

In addition, the metal oxide contained in the metal oxide thin film layer may have an average particle diameter of 10 nm or less, preferably 1 to 8 nm, and more preferably 3 to 7 nm.

The metal oxide is Ti, Zn, Si, Mn, Sr, In, Ba, K, Nb, Fe, Ta, W, Sa, Bi, Ni, Cu, Mo, Ce, Pt, Ag, Rh and combinations thereof It may be an oxide of any one metal selected from the group consisting of, it may be preferably ZnO. Since the ZnO has a wide band gap and has semiconductor properties, when used with the lower electrodes 101 and 201, the movement of electrons can be further improved.

The translucent organic solar cell 500 according to the present invention as described above can be manufactured according to a known bar method.

The method of manufacturing the semi-transparent organic solar cell 500 of the present invention includes forming a thin film layer by coating the substrate 100 with a coating solution while transferring the roll 100 in a roll-to-roll manner. At this time, the thin film layer may be at least one selected from the group consisting of an electron transport layer (102,202), a photoactive layer (103,203) and a hole transport layer (104,204), the coating solution includes the composition and solvent for forming the thin film layer. In the following description, the lower electrodes 101 and 201 are cathodes.

First, a substrate 100 is prepared and a cathode is formed on the substrate 100 with lower electrodes 101 and 201.

The cathode may be formed on the prepared substrate 100 according to a conventional method. Specifically, the cathode may be formed on one surface of the substrate 100 by forming a composition for forming a cathode through thermal vapor deposition, electron beam deposition, RF or magnetron sputtering, chemical vapor deposition, or a similar method.

At this time, prior to the formation of the cathode, at least one method selected from the group consisting of O ₂ plasma treatment, UV / ozone washing, surface washing using an acid or alkali solution, nitrogen plasma treatment, and corona discharge washing is selectively performed on the substrate. It can also be used to pre-treat the surface of the substrate.

Subsequently, the step of forming a thin film layer by coating the coating solution while transferring the substrate on which the lower electrodes 101 and 201 are formed in a roll-to-roll manner. At this time, the thin film layer is an electron transport layer (102 202), a photoactive layer (103 203) and a hole transport layer (104 204).

The coating solution includes a material and a solvent included in each thin film layer.

Specifically, the coating solution may be a composition for forming electron transport layers 102 and 202, a composition for forming photoactive layers 103 and 203, and a composition for forming hole transport layers 104 and 204.

Next, the electron transport layers 102 and 202 may be formed on the lower electrodes 101 and 201 using the composition for forming the electron transport layers 102 and 202.

The composition for forming the electron transporting layers 102 and 202 is prepared by dissolving the above-described metal oxide in a solvent and applying it to form a coating film.

The solvent may be used without particular limitation as long as it can dissolve or disperse the metal oxide. For example, water, 2-ethylhexanol, 2-butoxyhexanol, n-propyl alcohol, isopropyl alcohol, One or more selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol and dipropylene glycol may be used.

The solvent may be included in the amount of the remainder of the composition for forming the electron transport layer (102,202), specifically, may be included in 1 to 95% by weight relative to the total weight of the composition for forming the electron transport layer (102,202). When the content of the solvent exceeds 95% by weight, it is difficult to obtain the function of the desired coating layer, and when the content of the solvent is less than 1% by weight, it is difficult to form a thin film of uniform thickness.

The coating may be performed by conventional coating methods such as slot die coating, spin coating, gravure coating, bar coating, Mayer bar coating, spraying, dip coating, comma coating, curtain coating, and doctor blading. It may be implemented, specifically, slot die coating or spin coating may be performed.

After forming the coating film with the composition for forming the electron transport layers 102 and 202, a post-treatment process of drying or heat-treating the coated substrate 10 may be selectively performed. The drying may be performed through hot air drying, NIR drying, or UV drying at 50 to 400 ° C, specifically at 70 to 200 ° C for 1 to 30 minutes.

Next, the photoactive layers 103 and 203 may be formed on the electron transporting layers 102 and 202 using the composition for forming the photoactive layers 103 and 203.

The composition for forming the photoactive layers 103 and 203 is prepared by dissolving the above-described hole acceptor and electron acceptor in a solvent, and applying them to form a coating film.

The solvent can be used without particular limitation as long as it can dissolve or disperse the electron acceptor and hole acceptor. In one example, the solvent is water; Alcohols such as ethanol, methanol, propanol, isopropyl alcohol, and butanol; Or acetone, pentane, toluene, benzene, diethyl ether, methyl butyl ether, N-methylpyrrolidone, tetrahydrofuran, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, carbon tetrachloride, dichloromethane, dichloroethane, Organic solvents such as trichloroethylene, chloroform, chlorobenzene, dichlorobenzene, trichlorobenzene, cyclohexane, cyclopentanone, cyclohexanone, dioxane, terpineol, methyl ether ketone, or a mixture thereof. When preparing the composition for forming the electron transporting layers 102 and 202, it is preferable to appropriately select and use among the solvents described above according to the type of the target material.

The coating may be performed by conventional coating methods such as slot die coating, spin coating, gravure coating, bar coating, Mayer bar coating, spraying, dip coating, comma coating, curtain coating, and doctor blading. It may be implemented, specifically, slot die coating or spin coating may be performed.

After forming the coating film with the composition for forming the photoactive layers 103 and 203, a post-treatment process of drying or heat-treating the coated substrate 100 may be selectively performed. The drying may be performed through hot air drying, NIR drying, or UV drying at 50 to 400 ° C, specifically at 70 to 200 ° C for 1 to 30 minutes.

For example, in the case of the photoactive layers 103 and 203, a post-treatment process of drying and heat treatment at 25 to 150 ° C. for 5 to 145 minutes after the coating process may be performed. Appropriate control of the drying process and the heat treatment process can induce proper phase separation between the electron acceptor and the hole acceptor, and induce the orientation of the electron acceptor.

In the case of the heat treatment process, when the temperature is less than 25 ° C., the mobility of the electron acceptor and the hole receptor is low, so the heat treatment effect may be insignificant, and when the heat treatment temperature exceeds 150 ° C., performance is deteriorated due to deterioration of the electron acceptor. It may degrade. In addition, when the heat treatment time is less than 5 minutes, the mobility of the electron acceptor and the hole receptor is low, so the heat treatment effect may be insignificant, and when the heat treatment time exceeds 145 minutes, performance may be deteriorated due to deterioration of the electron acceptor. Can be.

Next, a hole transport layer 104,204 is formed on the photoactive layer 103,203 using a composition for forming a hole transport layer 104,204.

The composition for forming the hole transport layers 104 and 204 is a paste containing the above-described hole transport material and a solvent, and is patterned on the substrate 100 using a printing method.

The solvent contained in the composition for forming the hole transport layer 104,204 is used to uniformly mix the hole transport material and to adjust the viscosity, and may be used without particular limitation as long as it is commonly used in forming a paste in the related art.

Preferably, the solvent includes water; Alcohol solvents such as methanol, ethanol, propanol, isopropanol, butanol, and isobutanol; Ether solvents such as diethyl ether, dipropyl ether, dibutyl ether, butyl ethyl ether and tetrahydrofuran; Alcohol ether solvents such as ethylene glycol, propylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and ethylene glycol monobutyl ether; Ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; Amide solvents such as N-methyl-2-pyrrolidinone, 2-pyrrolidinone, N-methylformamide, and N, N-dimethylformamide; Sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide; Sulfone solvents such as diethyl sulfone and tetramethylene sulfone; Nitrile solvents such as acetonitrile and benzonitrile; Amine solvents such as alkylamines, cyclicamines, and aromaticamines; Ester solvents such as methyl butyrate, ethyl butyrate, and propyl propionate; Carboxylic acid ester solvents such as ethyl acetate and butyl acetate; Aromatic hydrocarbon solvents such as benzene, ethylbenzene, chlorobenzene, toluene and xylene; Aliphatic hydrocarbon solvents such as hexane, heptane and cyclohexane; Halogenated hydrocarbon solvents such as chloroform, tetrachloroethylene, carbon tetrachloride, dichloromethane and dichloroethane; Organic solvents such as propylene carbonate, ethylene carbonate, dimethyl carbonate, dibutyl carbonate, ethyl methyl carbonate, dibutyl carbonate, nitromethane, and nitrobenzene; one or more mixed solvents selected from the group consisting of may be used.

It is preferable that the composition for forming the hole transport layers 104 and 204 is optimized to be suitable for a printing process. Specifically, the composition for forming the hole transport layer 104,204 may have a viscosity in the range of 300 to 10,000 cps. If the viscosity of the composition for forming the hole transport layer (104,204) is less than the above range, spreading of the pattern may be caused. On the contrary, if it exceeds the above range, uniform dispersion of the hole transport material is difficult and there is a fear that printability may deteriorate. have.

The printing method in the present invention can be applied to various printing processes that are commonly used. For example, the printing may be any one of inkjet printing, aerosol jet printing, EHD jet printing, gravure printing, gravure offset printing, imprinting, flexo printing, or screen printing, preferably screen printing.

After performing the printing process, it may be fired according to the drying and firing methods commonly used in the art, preferably nitrogen, oxygen or argon hot air alone, MIR (Middle Infra Red) lamp, or hot air and MIR lamp Can be dried and fired simultaneously.

Next, surface treatment using the surface treatment agent as described above is performed on the hole transport layers 104 and 204. This surface treatment is not a necessary process, and can be selectively performed.

The surface treatment is performed over the entire hole transport layers 104 and 204, and drying is performed through the above-described drying method after application of the surface treatment agent.

Next, auxiliary electrodes 301 and 302 are formed to include one side of the thin film layers together with the upper one side of the hole transport layer 104 and include a part of the lower electrode of the neighboring unit cell.

The auxiliary electrodes 301 and 302 may be formed through a method of screen printing, gravure printing, gravure-offset printing, thermal vapor deposition, electron beam deposition, RF or magnetron sputtering, chemical vapor deposition, etc., rather than application.

The semi-transparent organic solar cell 500 according to the present invention is manufactured through the above steps.

At this time, the lamination of each layer on the substrate 100 may be performed in a roll-to-roll manner.

Specifically, the speed of transferring the substrate 100 in a roll-to-roll manner may be 0.01 m / min to 20 m / min, and preferably 0.1 m / min to 5 m / min. The transfer speed may be optimized according to the coating and drying speed of the individual layers using the roll-to-roll equipment.

The process using the roll-to-roll equipment facilitates mass production of semi-transparent organic solar cells, and it can be easily applied to large-area substrates with the advantage of being capable of continuous processing. Solar cells can be produced.

In addition, the semi-transparent organic solar cell manufactured through the above steps can increase the light transmittance by excluding the upper electrode to have a light transmittance of 40% or more as a whole, thereby realizing an organic solar cell in a semi-transparent state.

In addition, it is possible to achieve a reduction in overall cell thickness, that is, thinning, with an efficiency equivalent to that of a conventional translucent organic solar cell.

Such a translucent organic solar cell can be applied to various fields such as building exterior materials, such as exterior walls, roofs, and windows, as well as clothing, wrapping paper, wallpaper, automobile glass, and the like.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art to which the present invention pertains can easily practice. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein.

Example  And Comparative example : Manufacturing of organic solar cells

[Example 1]

While transferring the substrate film on which the ITO layer was formed in a roll-to-roll manner, a coating solution containing ZnO (prepared by mixing 1 ml of Zn (OAC) ₂ 2H ₂ O 247 mg, KOH 126 mg and 1-butanol) on the ITO layer) After slot die coating in stripe form, it was dried at 120 ° C to form a thin layer of ZnO metal oxide. When the slot die was coated, the line speed was 12 mm / sec, the slot die height was 1300 μm, and the coating liquid flow rate was set to 0.4 ml / min.

Subsequently, a coating solution for forming a photoactive layer on the ZnO metal oxide thin film layer (prepared by mixing 15 mg of lisicon ^® SP001 (manufactured by Merck), 12 mg of lisicon ^® A-600 (manufactured by Merck) and 1 ml of 1,2-dichlorobenzene) The slot die coating and drying at 120 ℃ to prepare a photoactive layer. When the slot die was coated, the line speed was 12 mm / sec, the slot die height was 1500 µm, and the coating liquid flow rate was 1.2 ml / min.

The optically active layer on a ^{PEDOT: PSS (Orgacon ® EL-} P 5010, agfa , Inc.) and about 30 ㎚ diameter and an aspect ratio of 1000: 1 is a nanowire 9: For the hole transport layer-forming composition containing a weight ratio of 1 slot When die coating, the line speed was 5 mm / sec, the slot die height was 800 µm, and the coating liquid flow rate was 3.0 ml / min, slot die coated, and dried at 120 ° C. (thickness 700 nm).

Subsequently, a semi-transparent organic solar cell was manufactured by depositing an Ag auxiliary electrode in a region between each unit cell.

[Example 2]

A semi-transparent organic solar cell was manufactured in the same manner as in Example 1, except that an ITO layer was formed as an auxiliary electrode.

[Comparative Example 1]

While transferring the substrate film on which the ITO layer was formed in a roll-to-roll manner, a coating solution containing ZnO (prepared by mixing 1 ml of Zn (OAC) ₂ 2H ₂ O 247 mg, KOH 126 mg and 1-butanol) on the ITO layer) After slot die coating in stripe form, it was dried at 120 ° C to form a thin layer of ZnO metal oxide. When the slot die was coated, the line speed was 12 mm / sec, the slot die height was 1300 μm, and the coating liquid flow rate was set to 0.4 ml / min.

Subsequently, a coating solution for forming a photoactive layer on the ZnO metal oxide thin film layer (prepared by mixing 15 mg of lisicon ^® SP001 (manufactured by Merck), 12 mg of lisicon ^® A-600 (manufactured by Merck) and 1 ml of 1,2-dichlorobenzene) The slot die coating and drying at 120 ℃ to prepare a photoactive layer. When the slot die was coated, the line speed was 12 mm / sec, the slot die height was 1500 µm, and the coating liquid flow rate was 1.2 ml / min.

The optically active layer on a PEDOT: the PSS (Orgacon ^® EL P-5010, agfa, Inc.) for the hole transport layer-forming composition and slot-die coating, and dried at 120 ℃ hole transport layer (thickness: 700 nm) containing the form. When the slot die was coated, the line speed was 5 mm / sec, the slot die height was 800 μm, and the coating liquid flow rate was 3.0 ml / min.

Subsequently, an organic solar cell was manufactured by printing an Ag electrode (thickness of 10 μm) on the hole transport layer using a screen printer.

Experimental Example  1: Performance evaluation of organic solar cells

The current-voltage characteristics of the organic solar cell manufactured in the above Examples and Comparative Examples were measured, and the results are shown in Table 1 below.

The current-voltage characteristics of the organic solar cell were measured using a solar simulator (66984, Newport). The solar imitation device used a 300W xenon lamp (Newport 6258) and an AM1.5G filter (Newport 81088A), and the light intensity was set to 100 mW / cm ² .

In addition, the series resistance was measured using a two-probe measurement method, and the optical transmittance was obtained for visible light transmittance at a wavelength of 380 to 780 nm according to Japanese Industrial Standard (JIS R 3106).

Voc ¹⁾ (V) Isc ^{2 )} (A) FF ³⁾ (%) Eff ^{4 )} (%) SR (Ω) AT (%) Example 1 6.81 0.07 36 2.28 60.8 100% Example 2 6.81 0.0001 18.9 0.0019 510446 100% Comparative Example 1 7.66 0.09 45 4.64 32.6 0% 1) Voc: open-circuit voltage, open voltage
2) Isc: short-circuit current, short-circuit current
3) FF: fill factor, fill factor
4) Eff: power conversion efficiency y, light conversion efficiency
5) SR: series reisistance, series resistance
6) AT: Anode Transmittance, Light Transmittance

Referring to Table 1, it can be seen that in the case of the organic solar cells of Examples 1 and 2 in which the auxiliary electrode was used according to the present invention, the light transmittance was 100%, and thus it could be used as a semi-transparent organic solar cell compared to Comparative Example 1.

In addition, in terms of voltage and current characteristics, the organic solar cells of Examples 1 and 2 showed results equal to or higher than those of Comparative Example 1 without using an upper electrode.

In addition, when comparing the organic solar cells of Examples 1 and 2, when using a metal material Ag as an auxiliary electrode even though it has a high light transmittance due to the exclusion of the upper electrode (Example 1) than when using ITO (implementation) Example 2) It was confirmed that it is advantageous in terms of series resistance (SR), which is more advantageous in terms of fill factor and light conversion efficiency.

The translucent organic solar cell according to the present invention exhibits excellent light transmittance, life and performance, and simplifies the manufacturing process to enable mass production of a translucent organic solar cell and is a building exterior material, such as exterior walls, roofs, windows, as well as fashion outdoor products. , It can be applied to various fields such as wrapping paper, wallpaper, automobile glass, etc.

10,100: substrate
11,21,101,201: lower electrode
12,22,102,202: electron transport layer
13,23,103,203: photoactive layer
14,24,104,204: hole transport layer
15,25: upper electrode
301,302: auxiliary electrode
50,500: Translucent organic solar cell

Claims (8)

Board; And in the translucent organic solar cell module having a plurality of unit cells formed on the substrate,
In the unit cell, a hole transport layer including a hole transport material and a conductive nanowire is sequentially stacked so that the lower electrode, the electron transport layer, the photoactive layer, and the upper electrode and the hole transport layer simultaneously function, and the structure excluding the upper electrode is formed. have,
For the electrical connection between the unit cells, an independent auxiliary electrode formed of an electrically conductive oxide, an electrically conductive nitride, or a metal is provided in a region between the unit cells,
The auxiliary electrode is a semi-transparent organic solar cell module, characterized in that electrically connecting the adjacent hole transport layer and the adjacent lower electrode. delete According to claim 1,
The hole transport layer is a translucent organic solar cell module in which a conductive nanowire forms a three-dimensional network structure in a matrix containing a hole transport material. According to claim 1,
The hole transport material is poly (3,4-ethylenedioxythiophene) (PEDOT), poly (styrenesulfonate) (PSS), polyaniline, phthalocyanine, pentacene, polydiphenyl acetylene, poly (t-butyl) diphenyl Acetylene, poly (trifluoromethyl) diphenylacetylene, copper phthalocyanine (Cu-PC) poly (bistrifluoromethyl) acetylene, polybis (T-butyldiphenyl) acetylene, poly (trimethylsilyl) diphenylacetylene, Poly (carbazole) diphenylacetylene, polydiacetylene, polyphenylacetylene, polypyridineacetylene, polymethoxyphenylacetylene, polymethylphenylacetylene, poly (t-butyl) phenylacetylene, polynitrophenylacetylene, poly (trifluoro Polymers comprising methyl) phenylacetylene and poly (trimethylsilyl) phenylacetylene; NPB (4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl); TPD (N, N'-bis (3-methylphenyl) -N, N'-diphenylbenzidine), MTDATA (4,4 ', 4 "-tris [(3-methylphenyl) phenylamino] triphenylamine), TAPC (4,4′-cyclohexylidene bis [N, N-bis (4-methylphenyl) benzeneamyl]), TCTA (tris (4-carbazoyl-9-ylphenyl) amine), CBP (4,4 ′ -Bis (N-carbazolyl) -1,1'-biphenyl), Alq3, mCP (9,9 '-(1,3-phenylene) bis-9H-carbazole) and 2-TNATA (4,4 An organic compound comprising ', 4 "-tris (N- (2-naphthyl) -N-phenylamino) triphenylamine); MoO ₃ , MoO ₂ , WO ₃ , V ₂ O ₅ , ReO ₃ , NiO, Mo (tfd) ₃ , HAT-CN (hexaazatriphenylene hexacarbonitrile) and F4-TCNQ (7,7,8,8 -Tetracyano-2,3,5,6-tetrafluoroquinodimethane); a translucent organic solar cell module comprising at least one member selected from the group consisting of; According to claim 1,
The conductive nanowire is a translucent organic solar cell module comprising at least one member selected from the group consisting of metal-based nanowires and carbon-based nanowires. The method of claim 5,
The metal nanowire is a semi-transparent organic solar cell module comprising at least one selected from the group consisting of Au, Ag, Pt, Cu, Ni, Fe, Pd, Rh, Ir, Co, Sn, Zn and Mo. The method of claim 5,
The carbon-based nanowire is a translucent organic solar cell module comprising at least one member selected from the group consisting of carbon nanotubes, carbon nanofibers, and graphene. According to claim 1,
The translucent organic solar cell module is a translucent organic solar cell module having a light transmittance of 40% or more.

Images