KR20190001126A - Organic photovoltaics and method for manufacturing the same - Google Patents

Abstract

The present invention relates to an organic solar cell and a method of manufacturing the same. More particularly, the present invention relates to an organic solar cell which includes: a substrate; a lower electrode formed on the substrate; an electron transport layer formed on the lower electrode; a photoactive layer formed on the electron transport layer; a hole transport layer formed on the photoactive layer, and an upper electrode formed on the hole transport layer. The electron transport layer comprises a metal oxide and an induced dipole polymer. The organic solar cell of the present invention can improve performance by improving the migration characteristics of electrons, thereby enabling the application to various fields.

Description

≪ Desc / Clms Page number 1 > ORGANIC PHOTOVOLTAICS AND METHOD FOR MANUFACTURING THE SAME

The present invention relates to an organic solar cell and a method of manufacturing the same.

Generally, a solar cell is a photovoltaic cell designed to convert solar energy into electrical energy, which means a semiconductor device that converts light energy generated from the sun into electrical energy. Such a solar cell is expected to be an energy source capable of solving future energy problems because it has low pollution, has an infinite resource, and has a semi-permanent life span.

In recent years, research on low-cost solar cells that reduce power generation costs and research on high-efficiency solar cells that improve conversion efficiency are under way at the same time.

Solar cells can be divided into inorganic solar cells and organic solar cells depending on the material constituting the photoactive layer among the internal constituent materials.

Inorganic solar cells are mainly made of monocrystalline silicon. Monocrystalline silicon solar cells are superior in terms of efficiency and stability, and account for most of the solar cells that are currently mass-produced. However, they are currently used for securing raw materials, lightening, softening, And it shows limitations in the development of painting technology.

On the other hand, since organic solar cells use organic materials such as a small molecule (expressed as a single molecule) or a polymer as an organic semiconductor material, they are much cheaper than the inorganic materials used in inorganic solar cells, It is possible to process and improve the productivity easily. In addition, since the process proceeds to a solution-based process at a relatively low temperature as compared with other semiconductor technologies, the manufacturing process can be simplified, high-speed, and large-sized. In particular, it has an advantage that it can be applied to various substrates such as low-priced glass or plastic which can be a problem in high-temperature processing.

1 is a cross-sectional view schematically showing the structure of a general organic solar cell.

1, the organic solar cell 100 includes a lower electrode 11, an electron transport layer 12, a photoactive layer 13, a hole transport layer 14, and an upper electrode 15 on a substrate 10 And have sequentially stacked structures. Generally, in the case of an inverted structure organic solar cell, the lower electrode 11 is a cathode and the upper electrode 15 is a cathode.

A transparent electrode including a transparent conductive oxide (TCO) having a high transparency and a work function is formed on the lower electrode 11, which is a surface where the light is incident on the organic solar cell 100, A metal electrode having a low work function is used for the electrode 15. In addition, the photoactive layer includes an organic semiconductor material, and may have a double-layer structure (D / A bi-layer structure) or an electron acceptor (bulk heterojunction) or an electron donor D + A) blend structure. In some cases, a mixed structure (D / (D + A) / A) in which the latter bulk heterojunction structure is interposed between two donor-acceptor layers of electrons may be used.

When an organic solar cell is irradiated with light, an electron-hole pair (Exciton) is formed by absorbing light from the electron-donating substance. The electron-hole pairs in the excited state diffuse in an arbitrary direction, and when they meet the interface with the electron-accepting material, they are separated into electrons and holes. That is, at the interface, electrons move toward the electron-accepting material having a high electron affinity, and the holes remain in the electron-donating substance to separate into the respective charge states. They are moved to the respective electrodes by the difference of the internal electric field formed by the work function difference of the both electrodes and the accumulated electric charge, and are finally collected in the form of current through the external circuit.

Various studies have been carried out on the structure and materials in order to increase the photoelectric conversion efficiency of such organic solar cells.

Among them, the electron injection barrier exists between the lower electrode, which is a transparent electrode, and the photoactive layer, so that the mobility of electrons separated from the photoactive layer is lowered, which is pointed out as a cause of lowering the photoelectric conversion efficiency of the organic solar cell. Recently, research on organic solar cells using an inductive dipole polymer that increases the photoelectric conversion efficiency by increasing the mobility of electrons by lowering the work function has been actively carried out.

For example, Korean Patent Laid-Open Publication No. 2016-0067340 discloses that the photoelectric conversion efficiency of an organic solar cell can be increased by forming an electron transport layer with a non-conjugated polymer electrolyte oxidized using hydrogen peroxide.

Korean Patent No. 10-1607478 discloses a technique of introducing an electron transport layer containing a surface-modified polymer layer and a functionalized metal oxide-graphene core-shell nanoparticle between an ITO electrode and a photoactive layer, And the photoelectric conversion efficiency of the organic solar battery can be improved by optimizing the band gap.

These patents have improved the photoelectric conversion efficiency of organic solar cells to some extent, but their effect is not sufficient and it is difficult to form them into thin films of several nanometers. In addition, changing or adding the material or the structure causes degradation of performance or lifetime of the organic solar battery. In addition, these conventional techniques are mostly suitable for spin coating processes and are difficult to apply to processes for mass production and large area production. Therefore, development of an organic solar cell that exhibits excellent photoelectric conversion efficiency, and is capable of large-area and mass production is further required.

Korean Patent Laid-Open Publication No. 2016-0067340 (June 06, 2014), Organic solar cell and manufacturing method thereof Korean Patent No. 10-1607478 (Feb. 26, 2014), a reverse-structured organic solar cell device using nanoparticles of nuclear-shell structure and a manufacturing method thereof

Accordingly, the present inventors have conducted various studies to solve the above-mentioned problems. As a result, they have found that when the electron transport layer contains a metal oxide and an induced dipolar polymer, the electron transporting property is improved and the photoelectric conversion efficiency of the organic solar battery can be enhanced And completed the present invention.

Accordingly, an object of the present invention is to provide an organic solar cell having excellent photoelectric conversion efficiency.

In order to achieve the above object, the present invention provides a semiconductor device comprising: a substrate; A lower electrode formed on the substrate; An electron transport layer formed on the lower electrode; A photoactive layer formed on the electron transporting layer; A hole transport layer formed on the photoactive layer, and an upper electrode formed on the hole transport layer,

The electron transport layer provides an organic solar cell including a metal oxide and an induced dipole polymer.

Wherein the metal oxide is selected from the group consisting of titanium, zinc, silicon, manganese, tin, gallium, aluminum, vanadium, strontium, indium, barium, potassium, niobium, iron, tantalum, tungsten, bismuth, nickel, chromium, zirconium, , Antimony, cerium, platinum, silver and rhodium.

The metal oxide has an average particle diameter of 0.1 to 10 nm.

The inductive dipole polymer includes at least one member selected from the group consisting of polyethyleneimine, polyethyleneimine ethoxylate, poly 2-ethyl-oxazoline, and polyallylamine.

The inductively coupled dipole polymer has a weight average molecular weight of 1,000 to 2,000,000 g / mol.

The weight ratio of the metal oxide to the induced dipole polymer is 1: 0.01 to 1: 1.

The electron transporting layer has a thickness of 1 to 100 nm.

The present invention also provides a method of manufacturing a semiconductor device, comprising: forming a lower electrode on a substrate; Forming an electron transport layer including a metal oxide and an induced dipole polymer on the lower electrode; Forming a photoactive layer on the electron transporting layer; Forming a hole transporting layer on the photoactive layer, and forming an upper electrode on the hole transporting layer.

The organic solar cell according to the present invention can improve the photoelectric conversion efficiency of the organic solar cell by using the metal oxide and the induced dipole polymer in the electron transport layer to reduce the high work function of the lower electrode and improve the electron transporting property. In addition, the organic solar cell can be easily applied to a roll-to-roll process through slot die coating, which enables the production of small-sized organic solar cells as well as large-area organic solar cells.

1 is a cross-sectional view schematically showing the structure of a general organic solar cell.
2 is a graph showing current-voltage characteristics of an organic solar cell according to Experimental Example 1 of the present invention.
3 is a graph showing a reliability evaluation result according to Experimental Example 1 of the present invention.

Hereinafter, the present invention will be described in detail.

When a member is referred to herein as being " on " another member, it includes not only a member in contact with another member but also another member between the two members.

Whenever a component is referred to as " comprising ", it is to be understood that the component may include other components as well, without departing from the scope of the present invention.

Conventionally, an organic solar cell includes an electron transport layer for smooth transfer of electrons between a lower electrode and a photoactive layer, and a metal oxide or an organic material is mainly used. However, due to the high electron injection barrier existing between the transparent conductive oxide used as the lower electrode and the organic semiconductor material composing the photoactive layer, the separation of electrons from the photoactive layer is not smooth, And the efficiency is lowered. Therefore, the electron transport layer may be formed of an induction dipole polymer having a property of lowering the work function of the electron transport layer by lowering the work function of the electron transport layer, or a layer containing an induction dipole polymer may be additionally formed on the electron transport layer, And a technique of increasing the photoelectric conversion efficiency by improving the mobility of the separated electrons while facilitating the separation of electrons and holes by reducing the injection barrier. However, in such a conventional technique, it is difficult to form a thin film having a uniform thickness in the electron transport layer, a sufficient performance improvement effect can not be obtained, and since a composition used for forming an electron transport layer is optimized for a spin coating process, It is difficult to apply it to a roll-to-roll slot die coating process.

Accordingly, the present invention provides an organic solar cell in which a lower electrode, an electron transporting layer, a photoactive layer, a hole transporting layer, and an upper electrode are sequentially stacked on a substrate, wherein an electron transporting layer including an inductive dipole polymer and a metal oxide is provided, The photoelectric conversion efficiency of the organic solar battery can be improved. In addition, since the electron transporting layer can form a uniform thin film having a thickness of 10 nm or less through slot die coating, it is advantageous for large-scale production, mass production and commercialization of organic solar cells through a roll-to-roll process.

An organic solar battery according to an embodiment of the present invention includes a substrate; A lower electrode formed on the substrate; An electron transport layer formed on the lower electrode; A photoactive layer formed on the electron transporting layer; A hole transport layer formed on the photoactive layer, and an upper electrode formed on the hole transport layer.

The substrate is not particularly limited as long as it has transparency.

For example, the substrate may be a transparent inorganic substrate such as quartz or glass or a transparent inorganic substrate such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), polystyrene (PS), polypropylene (PP) ), A transparent plastic substrate selected from the group consisting of polyethylene sulfonate (PES), polyoxymethylene (POM), polyetheretherketone (PEEK), polyethersulfone (PES), and polyetherimide Can be used. It is preferable to use a transparent plastic substrate in the form of a film which is flexible and has high chemical stability, mechanical strength and light transmittance.

Further, it is preferable that the substrate 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 is not particularly limited and may be suitably determined according to the intended use, for example, 1 to 500 탆.

The lower electrode is formed as a cathode on the above-described substrate.

Since the lower electrode is a path for allowing light passing through the substrate to reach the photoactive layer, it is preferable to use a conductive material having a high light transmittance and a high work function and a low resistance of about 4.5 eV or more.

As a material for forming the lower electrode, indium tin oxide (ITO), indium zinc oxide (IZO), indium gallium zinc oxide (IGZO), indium tin zinc oxide Doped zinc oxide (AZO), fluorine-doped tin oxide (FTO), zinc (ZnO), zinc-doped zinc oxide (Zinc Tin Oxide), indium gallium oxide (IGO), antimony tin oxide (ATO), zinc oxide (ZnO), indium oxide (In ₂ O ₃ ), tin oxide An electrically conductive oxide including SnO ₂ , tungsten oxide (WO ₃ ), vanadium oxide (V ₂ O ₅ ), molybdenum oxide (MoO ₃ ), and tellurium oxide (TeO ₂ ); (GaN), indium nitride (InN), aluminum gallium nitride (AlGaN) and aluminum nitride indium gallium (AlInGaN). Nitride; (Au), Ag, Pt, Cu, Ni, Fe, Ti, Al, Pd, Rh, Metals including iridium (Ir), cobalt (Co), tin (Sn), zinc (Zn), and molybdenum (Mo); Conductive polymers such as poly (3-methylthiophene), poly [3,4- (ethylene-1,2-dioxy) thiophene], polypyrrole and polyaniline, and graphene thin films, graphene oxide ) Thin films, and carbon materials such as carbon nanotube thin films. The electroconductive oxide and the electrically conductive nitride have an advantage of high light transmittance. The metal has an advantage of excellent electrical conductivity, and the conductive polymer and the carbon material have an advantage of excellent flexibility property.

The lower electrode may be formed of any of the above-described materials, or a combination of oxide / metal / oxide and metal-bonded carbon nanotube thin films.

The thickness of the lower electrode may be 10 to 3000 nm.

The electron transporting layer is positioned on the lower electrode and enhances the efficiency of the organic solar cell by increasing the electron transporting property. In addition, it is possible to prevent oxygen and moisture introduced from the outside from affecting the later-described photoactive layer.

In the present invention, the electron transporting layer includes a metal oxide and an induced dipole polymer.

The electron transport layer according to the present invention includes a metal oxide and an induced dipole at the same time, thereby effectively lowering the high work function of the transparent electrode, which is the lower electrode, As the movement becomes more smooth, the photoelectric conversion efficiency of the organic solar battery can be improved. In addition, since it is easy to apply to the slot die coating in addition to the spin coating, it has an advantage that mass production and large area production are possible through the roll-to-roll method.

The metal oxide has a broad bandgap and a semiconductor property, and thus has excellent electron transporting ability. Further, the metal oxide has excellent reactivity to air or moisture and has excellent light transmittance in the visible light region.

The metal oxide may be at least one selected from the group consisting of Ti, Zn, Si, Mn, Sn, Ga, Al, V, (Ti), tungsten (W), bismuth (Bi), nickel (Ni), chromium (Cr), nickel (Ni) At least one selected from the group consisting of zirconium (Zr), copper (Cu), molybdenum (Mo), antimony (Sb), cerium (Ce), platinum (Pt), silver (Ag) And may include an oxide of a metal.

Specifically, the metal oxide is titanium oxide (TiO _2), indium oxide (In ₂ O _3), tin oxide (SnO _2), zinc (ZnO), gallium oxide (Ga ₂ O _3), tungsten oxide (WO ₃ ), aluminum oxide (Al ₂ O _3), vanadium oxide _{(V 2 O 5, VO 2} , V 4 O 7, V 5 O 9, or V ₂ O _3), oxide molybdenum (MoO _3), copper oxide (CuO), nickel (NiO), copper aluminum oxide (CuAlO _2), zinc rhodium oxide (ZnRh ₂ O _4), iron oxide (FeO), chrome (Cr ₂ O _3), bismuth oxide (Bi ₂ O ₃₎ oxide (ZrO ₂ ), aluminum-doped zinc oxide (Al-ZnO), lithium-doped zinc oxide (Li-ZnO), gallium-doped zinc oxide (Ga-ZnO), niobium-doped titanium oxide TiO ₂ ) and antimony-doped titanium oxide (Sb-TiO ₂ ). Preferably, the metal oxide is at least one selected from the group consisting of zinc oxide and titanium oxide, more preferably zinc oxide.

The metal oxide may have an average particle diameter of 0.1 to 10 nm or less, preferably 1 to 9 nm, and more preferably 3 to 8.5 nm. When the average particle diameter of the metal oxide is less than the above-mentioned range, the electron mobility improving effect can not be obtained. On the other hand, if the average particle diameter exceeds the above range, the organic solar battery can be adversely affected.

The inductive dipole polymer may be a polymer capable of inducing an induced dipole by bonding with oxygen of the metal oxide, and may include a functional group including a nitrogen atom and not a dipole moment. Examples of the nitrogen-containing functional group include an amine group, an azo group, and an ammonium group. These functional groups may be included in the main chain or side chain of the polymer.

As described above, nitrogen atoms in the inductive dipole polymer combine with oxygen of the metal oxide to form an induced dipole. By lowering the electron injection barrier and lowering the open voltage as the work function is lowered by the induced dipole, The photoelectric conversion efficiency of the organic solar battery can be improved.

The inductive dipole polymer may be a polyethyleneimine-based polymer or a polyallyl amine-based polymer.

Specifically, the inductively coupled dipole polymer may be selected from the group consisting of polyethyleneimine (PEI), polyethyleneimine ethoxylated (PEIE), poly (2-ethyl-2-oxazoline) polyallylamine, etc. Preferably, the inductively coupled dipole polymer is at least one member selected from the group consisting of polyethyleneimine and polyethyleneimine ethoxylate, and more preferably at least one member selected from the group consisting of polyethylene It can be an immigration.

The induced dipole polymer may be a weight-average molecular weight (M _W) of 1,000 to 2,000,000 g / mol, preferably from 5,000 to 1,000,000 g / mol, more preferably 10,000 to 30,000 g / mol. If the weight average molecular weight of the inductively coupled dipole polymer is within the range described above, it may be easy to form a thin film.

The weight ratio of the metal oxide and the induction dipole polymer may be 1: 0.01 to 1: 1, preferably 1: 0.01 to 1: 0.5, more preferably 1: 0.01 to 1: 0.05. If the weight ratio of the two materials is less than the above range, the effect of improving the electron mobility is insufficient. On the contrary, when the weight ratio of the two materials is more than the above range, the insulating property is increased and the electron mobility may be disturbed.

The electron transporting layer may have a thickness of 1 to 100 nm, preferably 1 to 50 nm, more preferably 1 to 30 nm. The electron transport layer according to the present invention improves the photoelectric conversion efficiency by including the metal oxide and the induced dipole polymer, and can be formed uniformly with a thin film of several nanometers, which is advantageous for thinning the organic solar cell.

The photoactive layer is located on the electron transport layer and has a bulk heterojunction structure in which a hole receptor 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 member selected from the group consisting of polythiophene, polyphenylenevinylene, polyfulorene, polypyrrole, and copolymers thereof. The organic low-molecular semiconductor material may include one or more selected from the group consisting of pentacene, anthracene, tetracene, perylene, oligothiophene, and derivatives thereof. can do.

Specifically, the hole acceptor may be at least one selected from the group consisting of poly-3-hexylthiophene (P3HT), poly-3-octylthiophene (P3OT) 2-ethylhexyl) oxy] benzo [1,2-b: 4,5-b '] dithiophene-2,6-diyl} (3,4-b] thiophene}) (Poly ({4,8-bis [(2-ethylhexyl) oxy] benzo [ -diyl} {3-fluoro-2 - [(2-ethylhexyl) carbonyl] thieno [3,4-b] thiophenediyl}); PTB7, poly-p-phenylenevinylene (9,9'-dioctylfluorene), poly (2-methoxy-5- (2-ethyl-hexyloxy) -1,4-phenylene vinylene MEH-PPV) and poly (2-methyl-5- (3 ', 7'-dimethyloctyloxy)) - (poly (2-methoxy- And 1,4-phenylene vinylene (MDMOPPV), which may be used alone or in combination of two or more selected from the group consisting of poly (2-methyl-5- (3 ', 7'-dimethyloctyloxy) have.

The electron acceptor may include at least one selected from the group consisting of fullerene (C60), fullerene derivatives such as 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) butyric rigs Acid methyl ester ((6,6) -phenyl-C71- butyric acid methyl ester; PC 71 BM), (6,6) - thienyl -C61- butynyl rigs Acid methyl ester ((6,6) -thienyl -C6-butyric acid methyl ester (ThCBM), and carbon nanotubes.

For example, the photoactive layer preferably comprises a mixture of P3HT as a hole acceptor and PCBM as an electron acceptor, wherein the mixing weight ratio of P3HT and PCBM may be from 1: 0.1 to 1: 2.

The thickness of the photoactive layer may be 10 to 1000 nm, specifically 100 to 500 nm. If the thickness of the photoactive layer is less than the above range, sunlight can not be sufficiently absorbed and the photocurrent is lowered and the efficiency is expected to decrease. Conversely, when the thickness of the photoactive layer exceeds the above range, excited electrons and holes can not move to the electrode, Lt; / RTI >

The hole transport layer is positioned on the above-described photoactive layer and plays a role in ensuring smooth hole transport to the upper electrode, which will be described later. In addition, like the above-described electron transporting layer, it is prevented from flowing into the unit cell such as oxygen, moisture, impurities, and the like.

The hole transport layer is used for the production and transport of holes, and includes a polymer; Organic compounds; And at least one selected from the group consisting of inorganic materials.

Specifically, the polymers for hole transport include poly (3,4-ethylenedioxythiophene) (PEDOT), poly (styrenesulfonate) (PSS), polyaniline, phthalocyanine, pentacene, polydiphenylacetylene, Butyl) diphenylacetylene, poly (trifluoromethyl) diphenylacetylene, copper phthalocyanine (Cu-PC) poly (bistrifluoromethyl) acetylene, polybis (t- butyldiphenyl) acetylene, poly (trimethylsilyl) (Meth) acrylates, such as diphenylacetylene, diphenylacetylene, poly (carbazole) diphenylacetylene, polydiacetylene, polyphenylacetylene, polypyridine acetylene, polymethoxyphenylacetylene, polymethylphenylacetylene, (Trifluoromethyl) phenylacetylene, poly (trimethylsilyl) phenylacetylene, derivatives thereof, and combinations thereof. In the case of the bar Preferably a mixture of PEDOT and PSS.

The organic compound for hole transporting may be NPB (4,4'-bis (N-phenyl-1-naphthylamino) biphenyl, 4,4'-bis [N- (1-naphthyl) Phenyl); TPD (N, N'-bis (3-methylphenyl) -N, N'-diphenylbenzidine, N, N'- Tris [phenyl (m-tolyl) amino] triphenylamine, 4,4'-tetramethyl- (4-methylphenyl) benzeneamine, 4,4'-cyclohexylidenebis [N, N-bis (4-methylphenyl) 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- And 2-TNATA (4,4 ', 4'-Tris [2-naphthyl (phenyl) amino] triphenylamine, Phenylamine) may be used.

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, -TCNQ (7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane, 7,7,8,8-tetracyano-2,3,5,6-tetrafluoroquinodimethane) At least one selected from the group consisting of MoO ₃ and MoO ₃ is preferably used.

The thickness of the hole transporting layer may be 200 to 800 nm, preferably 300 to 500 nm.

The upper electrode is formed as an anode on the above-described hole transporting layer.

The upper electrode includes a conventional metal having a low work function.

For example, the upper electrode may be formed of at least one selected from the group consisting of Ag, Cu, Au, Pt, Ti, Al, Ni, Zr, Fe), manganese (Mn) and the like; Or a precursor containing the metal element, for example, silver nitrate _{(AgNO 3), Cu (HAFC} ) 2 (Cu (hexafluoroacetylacetonate) 2,), Cu (HAFC) (1,5-Cyclooctanediene), Cu (HAFC) (1 , 5-Dimethylcyclooctanediene), Cu (HAFC) (4-Methyl-1-pentene), Cu (HAFC) (Vinylcyclohexane), Cu (HAFC) (dimethylaluminum hydride), TMEDA (tetramethylethylenediamine ), DMEAA (dimethylethylamine alane, NMe 2 Et · AlH 3), TMA (trimethylaluminum), TEA (triethylaluminum), TBA (triisobutylaluminum), TDMAT (tetra (dimethylamino) titanium), TDEAT (tetra (dimethylamino) titanium), but is not limited thereto.

The thickness of the upper electrode may be 10 to 5000 nm.

The above-described organic solar cell according to the present invention can be manufactured by a known method.

The method for manufacturing an organic solar cell of the present invention includes a step of forming a thin film layer by coating a substrate with a coating solution while transferring the substrate by a roll-to-roll method. At this time, the thin film layer may be at least one selected from the group consisting of an electron transport layer, a photoactive layer and a hole transport layer, and the coating solution includes the composition and the solvent for forming the thin film layer. Hereinafter, the lower electrode is a cathode.

A method of fabricating an organic solar cell according to an embodiment of the present invention includes: forming a lower electrode on a substrate; Forming an electron transport layer including a metal oxide and an induced dipole polymer on the lower electrode; Forming a photoactive layer on the electron transporting layer; Forming a hole transport layer on the photoactive layer, and forming an upper electrode on the hole transport layer.

First, a substrate is prepared and a cathode is formed as a lower electrode on the substrate.

The cathode on the prepared substrate can be formed according to a conventional method. Specifically, the negative electrode may be formed on one side of the substrate by thermal vapor deposition, electron beam deposition, RF or magnetron sputtering, chemical vapor deposition, or the like.

At least one method selected from the group consisting of O ₂ plasma treatment, UV / ozone cleaning, surface cleaning using an acid or an alkali solution, nitrogen plasma treatment, and corona discharge cleaning may be selectively performed on the substrate prior to the formation of the cathode The surface of the substrate may be pre-treated.

And then applying a coating solution while transferring the substrate on which the lower electrode is formed by a roll-to-roll method to form a thin film layer. At this time, the thin film layer is an electron transporting layer, a photoactive layer, and a hole transporting layer.

The coating solution includes a substance and a solvent contained in each thin film layer.

Specifically, the coating solution may be a composition for forming an electron transport layer, a composition for forming a photoactive layer, and a composition for forming a hole transport layer.

Hereinafter, the step of forming each thin film layer will be described in detail.

Next, an electron transporting layer can be formed using a composition for forming an electron transporting layer on the lower electrode.

The composition for forming an electron transport layer of the present invention comprises a metal oxide and an inductively dipolar polymer as described above, and is prepared by dissolving the metal oxide and the dipolar polymer in a solvent, and applying the coating to form a coating film.

The solvent is not particularly limited as long as it can dissolve or disperse the metal oxide and the induction dipole polymer. Examples thereof include water, 2-ethylhexanol, 2-butoxyhexanol, At least one selected from the group consisting of isopropyl alcohol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol and dipropylene glycol can be used.

The solvent may be contained in an amount of the remainder in the composition for forming an electron transport layer, specifically, 1 to 95% by weight based on the total weight of the composition for forming an electron transport layer. When the content of the solvent exceeds 95 wt%, it is difficult to obtain the function of the desired coating layer. When the content of the solvent is less than 1 wt%, it is difficult to form a thin film having a uniform thickness.

The application may be carried out by various methods such as bar coating, gravure coating, microgravure coating, flexo coating, knife coating, spray coating, slot die coating, roll coating, screen coating, inkjet printing, casting, dip coating, Curtain coating, comma coating, kiss coating, and spin coating. In particular, the electron transport layer according to the present invention preferably uses a slot die coating.

After the coating film is formed by the composition for forming an electron transport layer, a post-treatment process of drying or heat-treating the coated substrate may be selectively performed. The drying may be performed by 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 layer can be formed on the electron transporting layer using the composition for forming a photoactive layer.

The composition for forming a photoactive layer is prepared by dissolving the above-described hole receptor and electron acceptor in a solvent, and applying the composition 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 the hole acceptor. In one example, the solvent is water; Alcohols such as ethanol, methanol, propanol, isopropyl alcohol and butanol; Or an organic solvent such as acetone, pentane, toluene, benzene, diethyl ether, methyl butyl ether, N-methylpyrrolidone, tetrahydrofuran, dimethylformamide, dimethylacetamide, dimethylsulfoxide, carbon tetrachloride, dichloromethane, Organic solvents such as trichlorethylene, chloroform, chlorobenzene, dichlorobenzene, trichlorobenzene, cyclohexane, cyclopentanone, cyclohexanone, dioxane, terpineol and methyletherketone, or mixtures thereof, The composition for forming the electron transport layer (102, 202) is preferably suitably selected from the above-described solvents depending on the kind of the target substance.

The application may be carried out by various methods such as bar coating, gravure coating, microgravure coating, flexo coating, knife coating, spray coating, slot die coating, roll coating, screen coating, inkjet printing, casting, dip coating, Curtain coating, comma coating, kiss coating, and spin coating. Specifically, slot die coating or spin coating may be performed.

After the coating layer is formed with the composition for forming a photoactive layer, a post-treatment process of drying or heat-treating the coated substrate may be selectively performed. The drying may be performed by 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 a photoactive layer, post-treatment may be performed after drying and heat treatment at 25 to 150 ° C for 5 to 145 minutes after the coating process. By appropriately controlling the drying step and the heat treatment step, appropriate phase separation can be induced between the electron acceptor and the hole acceptor, and the orientation of the electron acceptor can be induced.

If the temperature is less than 25 ° C, the mobility of the electron acceptor and the hole acceptor may be low and the heat treatment effect may be insignificant. If the annealing temperature exceeds 150 ° C, Can be degraded. If the heat treatment time is less than 5 minutes, the mobility of the electron acceptor and the hole acceptor may be low and the heat treatment effect may be insufficient. If the heat treatment time exceeds 145 minutes, the performance deteriorates due to deterioration of the electron acceptor .

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

The composition for forming a hole transport layer is prepared by dissolving the hole transport material described above in a solvent and applying the composition to form a coat.

The solvent contained in the composition for forming a hole transport layer is used for uniformly mixing and dispersing the hole transport material and is not particularly limited as long as it is commonly used 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 alkyl amines, cyclic amines, and aromatic amines; 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, tetrachlorethylene, carbon tetrachloride, dichloromethane and dichloroethane; An organic solvent such as ethylene carbonate, propylene carbonate, ethylene carbonate, dimethyl carbonate, dibutyl carbonate, ethyl methyl carbonate, dibutyl carbonate, nitromethane, nitrobenzene and the like can be used.

The solvent may be contained in an amount of the remainder of the composition for forming a hole transport layer, and may be specifically included in an amount of 1 to 95% by weight based on the total weight of the composition for forming the hole transport layer. When the content of the solvent exceeds 95 wt%, it is difficult to obtain the function of the desired coating layer. When the content of the solvent is less than 1 wt%, it is difficult to form a thin film having a uniform thickness.

The application may be carried out by various methods such as bar coating, gravure coating, microgravure coating, flexo coating, knife coating, spray coating, slot die coating, roll coating, screen coating, inkjet printing, casting, dip coating, Curtain coating, comma coating, kiss coating, and spin coating. Specifically, slot die coating or spin coating may be performed.

After the coating film is formed using the composition for forming a hole transport layer, a post-treatment process of drying or heat-treating the coated substrate may be selectively performed. The drying may be performed by 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, an anode is formed as an upper electrode on the hole transport layer.

The composition for forming an anode is a paste containing the material of the upper electrode described above, and is formed into a predetermined pattern using a printing method.

In the present invention, a variety of commonly used printing processes can be applied to the printing method. For example, the printing may be performed by any one of ink jet printing, aerosol jet printing, EHD jet printing, gravure printing, gravure-offset printing, imprinting, flexographic printing or screen printing, Is screen printing.

After the printing process is performed, it may be fired according to a drying and firing method commonly used in the art, preferably a nitrogen, oxygen, or argon hot air alone, a Middle Infra-Red (MIR) lamp, The lamp can be dried and fired simultaneously.

The organic solar cell according to the present invention is manufactured through the above steps.

At this time, the lamination of each layer on the substrate can proceed in a roll-to-roll manner.

Specifically, the speed at which the substrate is transported by the roll-to-roll method may be from 0.01 m / min to 20 m / min, and preferably from 0.1 m / min to 5 m / min. The conveying speed can be optimally used according to the coating and drying speed of the individual layers using the roll-to-roll equipment.

Since the process using the roll-to-roll equipment is easy to mass-produce organic solar cells and can be continuously processed, it can be easily applied to a large-sized substrate. Therefore, regardless of the size thereof, .

In addition, the organic solar cell of the present invention manufactured through the above steps includes an electron transporting layer including a metal oxide and an inductively coupled dipole polymer, so that electrons can be smoothly moved, thereby realizing an organic solar cell exhibiting excellent photoelectric conversion efficiency .

Such an organic solar cell is applicable to a variety of applications such as building exterior materials such as outer walls, roofs, and windows, as well as clothes, wrapping paper, wallpaper, and automobile glass.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

Example  And Comparative Example : Manufacture of Organic Solar Cells

[Example 1]

While transferring the substrate film, the ITO layer formed in a roll-to-roll method immigration zinc and polyethylene oxide on the ITO layer _{(M W = 25,000 g / mol} ) 1: 0.01 slot the coating solution for an electron transport layer formed in a weight ratio in the form of stripes Followed by drying at 120 캜 to form an electron transporting layer having a thickness of 30 nm. The slot die coating was performed at a line speed of 5 mm / sec, a slot die height of 100 m, and a coating liquid flow rate of 0.4 ml / min.

(Prepared by mixing 12 mg of PTB7 (Sigma aldrich), 18 mg of PC ₇₁ BM (Sigma aldrich) and 1 ml of xylene) on the electron transport layer, To form a 300 nm thick photoactive layer. The slot die coating was performed at a line speed of 5 mm / sec, a slot die height of 100 m, and a coating liquid flow rate of 0.5 ml / min.

A coating solution for forming a hole transport layer Clevios HTL Solar (Heraeus Co.) was coated on the photoactive layer by slot die coating and dried at 120 ° C to form a 500 nm thick hole transport layer. The slot die coating was performed by slot die coating at a line speed of 5 mm / sec, a slot die height of 100 m, and a coating liquid flow rate of 1.0 ml / min, followed by drying at 120 ° C.

Subsequently, a 120 nm thick silver layer was formed on the photoactive layer using a thermal evaporator under a vacuum of 10 torr to form an anode, thereby preparing an organic solar cell.

[Example 2]

An organic solar cell was prepared in the same manner as in Example 1, except that zinc oxide and polyethyleneimine were contained in a weight ratio of 1: 0.02 in the preparation of a coating solution for forming an electron transport layer.

[Example 3]

An organic solar cell was prepared in the same manner as in Example 1, except that zinc oxide and polyethyleneimine were contained in a weight ratio of 1: 0.03 in the preparation of a coating solution for forming an electron transport layer.

[Example 4]

A coating solution for forming an electron transport layer containing zinc oxide and polyethyleneimine in a weight ratio of 1: 0.03 was spin-coated on a base film on which an ITO layer was formed, and then heat-treated at 200 ° C for 2 minutes and dried to form a 40 nm thick electron transport layer Respectively. The spin coating speed was 4000 rpm.

(Prepared by mixing 12 mg of PTB7 (Sigma aldrich), 18 mg of PC ₇₁ BM (Sigma aldrich) and 1 ml of xylene) on the electron transport layer, and the mixture was spin-coated at 80 ° C Treated for 2 minutes to prepare a 300 nm thick photoactive layer. The spin speed of the spin-spin coating was 1000 rpm.

A coating solution (Clevios HTL Solar (Heraeus)) for forming a hole transport layer was spin-coated on the photoactive layer and dried at 120 ° C to form a 200 nm thick hole transport layer. The spin speed was 1000 rpm Respectively.

Subsequently, a 120 nm thick silver layer was formed on the photoactive layer using a thermal evaporator under a vacuum of 10 torr to form an anode, thereby preparing an organic solar cell.

[Comparative Example 1]

An organic solar cell was prepared in the same manner as in Example 1 except that zinc oxide was used in preparing a coating solution for forming an electron transport layer.

[Comparative Example 2]

An organic solar cell was prepared in the same manner as in Example 4 except that zinc oxide was used in the preparation of a coating solution for forming an electron transport layer.

[Comparative Example 3]

An organic solar cell was prepared in the same manner as in Example 4 except that polyethyleneimine was used in the preparation of a coating solution for forming an electron transport layer.

Experimental Example  1: Performance evaluation of organic solar cell 1

The photoelectric conversion characteristics, the current-voltage characteristics and the reliability of the organic solar cells prepared in Examples 1 to 3 and Comparative Example 1 were measured. The results are shown in Tables 1, 2 and 3.

The current-voltage characteristics of the organic solar cells prepared in the Examples and Comparative Examples were measured using a solar simulator (Newport 94083). The solar simulator used was a 1600 W Xenon lamp (Newport 62726) and an AM 1.5G filter (Newport 81088A), and the intensity of light was set to 100 mW / cm ² .

The reliability evaluation was conducted for 1200 hours.

Voc ^{1 )} (V) Isc ^{2 )} (㎃) Jsc ^{3 )} (mA / cm ² ) FF ⁴⁾ (%) PCE ^{5 )} (%) Example 1 7.88 83.10 1.14 51.56 4.64 Example 2 7.91 85.96 1.18 51.64 4.82 Example 3 7.89 87.68 1.20 52.20 4.96 Comparative Example 1 7.93 81.80 1.12 49.78 4.44 1) Voc: open-circuit voltage, open-circuit voltage
2) Isc: short-circuit current, short-circuit current
3) Jsc: short-circuit photocurrent density, short-circuit current density
4) FF: fill factor, charge rate
5) PCE: Power Conversion Efficiency, Energy Conversion Efficiency

In Table 1, the open-circuit voltage (Voc) and the short-circuit current density (Jsc) are X-axis and Y-axis intercepts in the fourth quadrant of the voltage-current density curve, respectively, and the filling rate (FF) Divided by the product of the open-circuit voltage (Voc) and the short-circuit current density (Jsc). Also, the energy conversion efficiency (PCE) can be obtained by dividing these three values by the intensity of the irradiated light. The higher the numerical values showing the photoelectric conversion characteristics, the better the efficiency and performance of the solar cell. In the case of the embodiment, it can be confirmed that the solar cell has a similar or improved value to that of the comparative example.

Referring to Table 1, the organic solar cell of Examples 1 to 3 including the electron transport layer according to the present invention has excellent overall photoelectric conversion characteristics as compared with Comparative Example 1, specifically, the open-circuit voltage is low, The efficiency is high.

In addition, in the current-voltage characteristics shown in FIG. 2, the organic solar cells of Examples 1 to 3 showed improved results as compared with Comparative Example 1 including the conventional electron transporting layer.

In addition, according to the reliability evaluation result of FIG. 3, it can be confirmed that Example 3 exhibits a remarkably high efficiency over the evaluation time of Comparative Example 1.

Experimental Example  2: Performance evaluation of organic solar cell unit device

The photoelectric conversion characteristics of the organic solar cell unit devices manufactured in Example 4, Comparative Example 2, and Comparative Example 3 were measured, and the results are shown in Table 2 below.

The current-voltage characteristics of the organic solar cell unit devices manufactured in the above Examples and Comparative Examples were measured using a solar simulator (Newport 94083). The solar simulator used was a 1600 W Xenon lamp (Newport 62726) and an AM 1.5G filter (Newport 81088A), and the intensity of light was set to 100 mW / cm ² .

Voc ^{1 )} (V) Isc ^{2 )} (㎃) Jsc ^{3 )} (mA / cm ² ) FF ⁴⁾ (%) PCE ^{5 )} (%) Example 4 0.79 0.63 15.74 71.58 8.93 Comparative Example 2 0.79 0.60 14.88 69.48 8.15 Comparative Example 3 0.76 0.68 16.88 68.63 8.85 1) Voc: open-circuit voltage, open-circuit voltage
2) Isc: short-circuit current, short-circuit current
3) Jsc: short-circuit photocurrent density, short-circuit current density
4) FF: fill factor, charge rate
5) PCE: Power Conversion Efficiency, Energy Conversion Efficiency

Referring to Table 2, it can be seen that Example 4 according to the present invention exhibits excellent photoelectric conversion characteristics as compared with Comparative Examples 2 and 3, and in particular, energy conversion efficiency is improved in Example 4.

The organic solar cell according to the present invention exhibits excellent photoelectric conversion efficiency and can simplify the manufacturing process and enable mass production and large area production of the organic solar battery, , Wrapping paper, wallpaper, automobile glass, and the like.

10: substrate 11: lower electrode
12: electron transport layer 13: photoactive layer
14: hole transport layer 15: upper electrode
100: Organic solar cell

Claims (10)

Board;
A lower electrode formed on the substrate;
An electron transport layer formed on the lower electrode;
A photoactive layer formed on the electron transporting layer;
A hole transporting layer formed on the photoactive layer and
And an upper electrode formed on the hole transport layer,
Wherein the electron transport layer comprises a metal oxide and an induced dipole polymer. The method according to claim 1,
Wherein the metal oxide is selected from the group consisting of titanium, zinc, silicon, manganese, tin, gallium, aluminum, vanadium, strontium, indium, barium, potassium, niobium, iron, tantalum, tungsten, bismuth, nickel, chromium, zirconium, , At least one metal selected from the group consisting of antimony, cerium, platinum, silver and rhodium. The method according to claim 1,
Wherein the metal oxide is selected from the group consisting of titanium oxide, indium oxide, tin oxide, zinc oxide, gallium oxide, tungsten oxide, aluminum oxide, vanadium oxide, molybdenum oxide, copper oxide, nickel oxide, At least one selected from the group consisting of chromium, bismuth oxide, zirconium oxide, aluminum-doped zinc oxide, lithium-doped zinc oxide, gallium-doped zinc oxide, niobium-doped titanium oxide and antimony-doped titanium oxide Organic solar cell. The method according to claim 1,
Wherein the metal oxide has an average particle diameter of 0.1 to 10 nm. The method according to claim 1,
Wherein the inductive dipole polymer comprises at least one member selected from the group consisting of polyethyleneimine, polyethyleneimine ethoxylate, poly 2-ethyl-oxazoline, and polyallylamine. The method according to claim 1,
Wherein the inductive dipole polymer has a weight average molecular weight of 1,000 to 2,000,000 g / mol. The method according to claim 1,
Wherein the weight ratio of the metal oxide and the induction dipole polymer is 1: 0.01 to 1: 1. The method according to claim 1,
Wherein the electron transporting layer has a thickness of 1 to 100 nm. Forming a lower electrode on the substrate;
Forming an electron transport layer including a metal oxide and an induced dipole polymer on the lower electrode;
Forming a photoactive layer on the electron transporting layer;
Forming a hole transport layer on the photoactive layer, and
And forming an upper electrode on the hole transport layer. 10. The method of claim 9,
Wherein the electron transport layer is formed by a slot die coating process.

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