KR101565338B1 - Organic solar cell and method for manufacturing the same - Google Patents

Abstract

The present invention provides an organic solar cell including an organic film patterned using a dry etching method and capable of exhibiting improved cell characteristics without fear of residual organic matter after patterning and current leak due to the organic film, .

Description

TECHNICAL FIELD [0001] The present invention relates to an organic solar cell and a method of manufacturing the same.

The present invention relates to an organic solar cell exhibiting improved cell characteristics due to a reduction in leakage current and a method for manufacturing the same.

Organic solar cells can be classified into conjugated polymers such as polyparaphenylenevinylene (PPV) in which double bonds are alternated, photosensitive low molecules such as CuPc, perylene, pentacene, or (6,6) And organic semiconductor materials such as C ₆₁ -butyric acid methyl ester (PCBM).

The organic solar cell basically has a thin film structure, and is generally disposed between the anode and the cathode opposite to each other, and is disposed between the anode and the cathode. The organic solar cell includes a hole acceptor such as a conjugated polymer, An electron acceptor is composed of a photoactive layer including an organic material having a bonding structure and further includes an organic layer of an electron transport layer and an electron transport layer on upper and lower portions of the photoactive layer as necessary.

When light is incident on the organic solar cell from an external light source, the light passes through the anode and enters the photoactive layer, and the photons that form the incident light collide with the electrons of the valence band existing in the electron acceptor of the photoactive layer. The electrons of the valence band take energy corresponding to the wavelength of the photon from the collided photon and jump to the conduction band, and holes are left in the valence band. The holes left in the electron acceptor move to the anode, the electrons in the conduction band move to the cathode, and the electrons and holes moved to each electrode cause the organic solar cell to have an electromotive force and operate as a power source.

Such an organic solar cell is advantageous in that it can be mass-produced with ease of processability and low price, and it is possible to produce a thin film by a roll-to-roll method, thereby making it possible to fabricate a large-area electronic device having flexibility . However, despite the technical and economical advantages as described above, it is difficult to put it into practical use because of its low efficiency. Accordingly, a method for efficiently utilizing the absorbed light through the selection of an optimal organic material in the organic layer including the photoactive layer, the electron transport layer, and the hole transport layer, or the development of the organic layer manufacturing process, the shape, structure, A method of increasing the charge mobility through the increase of the electron mobility, and the like.

In the production of an organic solar cell, a patterning method of forming an organic film containing a photoactive layer in a desired pattern is one of particularly important techniques. Conventional organic film patterning methods include vacuum vapor deposition, laser induced thermal imaging (LITI), ink jet printing, slot die coating, mechanical scribing ) Were used.

However, the vacuum deposition method has a limitation that can be applied only to low molecular materials, and the laser transfer method also has excellent processability and film properties, but it is applicable only to low molecular materials. The inkjet printing method can be used for a polymer material, and it is possible to implement a stripe pattern. However, since a process for forming a barrier or a surface treatment is required to be deposited only in a desired place before an inkjet process, The manufacturing cost is increased, and the film quality of the formed organic film is also poor. In the case of the mechanical scribing method, an organic film is coated on the entire surface of a substrate, and then an unnecessary portion of the organic film is scraped off. As a result, the precision is lowered, the organic film is damaged, organic substances are likely to remain on the substrate, There is a problem that current leakage due to organic materials is increased and battery characteristics of the organic solar battery are deteriorated.

Korean Registered Patent No. 1076700 (registered on October 19, 2011)

SUMMARY OF THE INVENTION It is an object of the present invention to provide an organic solar cell exhibiting improved battery characteristics due to reduced current leakage due to residual organic matter generated in the production of organic solar cells and a method of manufacturing the same.

An organic solar cell according to an embodiment of the present invention includes:

anode,

An organic layer disposed on the anode and including a photoactive layer,

A first cathode located on the organic film, and

And a second cathode disposed on the first cathode.

Wherein the organic film comprises at least one selected from the group consisting of a hole transporting layer located between the anode and the photoactive layer and including a hole transporting material and an electron transporting layer located between the photoactive layer and the first cathode, Layer. ≪ / RTI >

The organic solar cell may further include a metal mask layer between the first and second cathodes.

The metal mask layer may include a metal selected from the group consisting of chromium, gold, ruthenium, rhodium, palladium, osmium, iridium, and platinum.

According to another aspect of the present invention, there is provided a method of manufacturing an organic solar cell,

Forming an anode;

Forming an organic film including a photoactive layer on the anode;

Forming a first anode on the organic layer;

Patterning the organic film by dry etching using the first negative electrode as a mask; And,

And forming a second cathode on the first cathode.

The method of manufacturing an organic solar cell may further include forming a hole transport layer including a hole transport material on the anode before forming the photoactive layer after the anode formation step and forming a first anode after forming the photoactive layer, And forming an electron transport layer containing an electron transfer material on the photoactive layer before the step of forming the photoactive layer.

The method of fabricating the organic solar cell may further include forming a metal mask layer on the first cathode before patterning the organic layer after the first cathode forming step.

The dry etching may be performed by a reactive ion etching method.

The dry etching may be performed using an active gas selected from the group consisting of O ₂ , Ar, N ₂ , CHF ₃ , CH ₄ , CF ₄ , SF ₆ , Cl ₂ , and BCl ₂ .

The dry etching may be performed under a pressure of 50 to 500 mTorr.

The dry etching may be performed by applying a voltage of 50 to 1000 W.

Other details of the embodiments of the present invention are included in the following detailed description.

In the organic solar cell according to the present invention, the organic film is patterned using a dry etching process, so that there is no concern about the residual organic matter and the current leakage due to the patterning, and the improved battery characteristics can be exhibited.

1 is a cross-sectional perspective view illustrating an organic solar cell according to an embodiment of the present invention.
2 is a process diagram illustrating a method of manufacturing an organic solar cell according to another 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 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.

As used herein, the terms "comprise", "having", and the like are intended to specify that there are stated features, integers, steps, operations, elements, parts, or combinations thereof, But do not preclude the presence or addition of features, numbers, steps, operations, components, parts, or combinations thereof.

Hereinafter, an organic solar cell according to the present invention and a method of manufacturing the same will be described in detail.

The present invention relates to an organic solar cell including an anode and a cathode positioned opposite to each other, and an organic film including a photoactive layer between the anode and the cathode, wherein the organic film is patterned by dry etching using the cathode as a mask Thereby preventing the organic matter from remaining after the patterning and minimizing the current leakage, thereby improving the electrical characteristics of the organic solar battery.

That is, an organic solar cell according to an embodiment of the present invention includes: an anode; An organic layer located on the anode and including a photoactive layer; A first cathode positioned above the organic layer; And a second cathode disposed on the first cathode.

1 is a perspective view illustrating an organic solar cell according to an embodiment of the present invention.

1, an organic solar cell 100 includes an anode 10, an organic layer 20 located on the anode, including a photoactive layer 20a, a first cathode 30a located on the photoactive layer, And a second cathode layer 30b positioned on the first cathode.

The anode 10 may be formed on the substrate 1.

The substrate 1 can be used without any particular limitation as long as it has transparency. Specifically, 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), polyimide Any transparent plastic substrate selected from the group consisting of polyethylene sulfonate (PES), polyoxymethylene (POM), polyetheretherketone (PEEK), polyether sulfone (PES) and polyetherimide have. Of these, it is preferable to use a transparent plastic substrate which is flexible and has high chemical stability, mechanical strength and transparency.

Further, the substrate 1 preferably has a transmittance of at least 70% or more, preferably 80% or more at a visible light wavelength of about 400 to 750 nm.

Since the anode 10 is a path through which the light passing through the substrate 1 can reach the photoactive layer 20a, the anode 10 has a high work function and a high work function and a low resistance of about 4.5 eV or more. Is preferably used. More specifically, tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), ZnO-Ga ₂ O ₃ , ZnO-Al ₂ O ₃ , SnO ₂ -Sb ₂ O _3, and combinations thereof; An organic transparent electrode such as a conductive polymer, a graphene thin film, a graphene oxide thin film, or a carbon nanotube thin film; Or an organic-inorganic bonding transparent electrode such as a carbon nanotube thin film to which a metal is bonded.

An organic layer 20 including a photoactive layer 20a is disposed on the anode 10.

The photoactive layer 20a 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 any one selected from the group consisting of polythiophene, polyphenylenevinylene, polyfulorene, polypyrrole, copolymers thereof, and combinations thereof. Wherein the organic low molecular weight semiconductor material is selected from the group consisting of pentacene, anthracene, tetracene, perylene, oligothiophene, derivatives thereof, and combinations thereof. And can be any one selected.

Preferably, the hole acceptor is selected from the group consisting of poly-3-hexylthiophene (P3HT), poly-3-octylthiophene (P3OT), poly- p-phenylenevinylene, PPV], poly (9,9'-dioctylfluorene), poly (2-methoxy-5- (2-ethyl-hexyloxy) Poly (2-methoxy-5- (2-ethyl-hexyloxy) -1,4-phenylenevinylene, MEH-PPV] ) -1,4-phenylene vinylene, MDMOPPV], and combinations thereof. The term " poly (2-methyl-5- It can be either.

The electron acceptor may be any nanoparticle selected from the group consisting of fullerene (C ₆₀ ) or a fullerene derivative, CdS, CdSe, CdTe, ZnSe, and combinations thereof. In addition, the electron acceptor (6,6) -phenyl -C ₆₁ - butyric rigs Acid methyl ester _{[(6,6) -phenyl-C 61} -butyric acid methyl ester; PCBM], (6,6) - phenyl -C ₇₁ - butyric rigs Acid methyl ester _{[(6,6) -phenyl-C 71} -butyric acid methyl ester; _{C 70 -PCBM], (6,6)} - thienyl -C ₆₁ - butyric rigs Acid methyl ester _{[(6,6) -thienyl-C 61} -butyric acid methyl ester; ThCBM], carbon nanotubes, and combinations thereof.

The photoactive layer 20a preferably includes a mixture of P3HT and PCBM as an electron acceptor, wherein the mixture weight ratio of P3HT and PCBM may be 1: 0.1 to 1: 2.

The organic layer 20 may further include a hole transport layer 20b including a hole transport material between the anode 10 and the photoactive layer 20a.

The hole transporting layer 20b may be formed of at least one selected from the group consisting of poly (3,4-ethylenedioxythiophene) (PEDOT), poly (styrenesulfonate) (PSS), polyaniline, phthalocyanine, pentacene, polydiphenylacetylene, ) Poly (trimethylsilyl) di (triphenylmethyl) diphenyl acetylene, poly (trifluoromethyl) diphenylacetylene, copper phthalocyanine (Cu-PC) poly (bistrifluoromethyl) acetylene, (Meth) acrylates, such as phenylacetylene, poly (acetylenes), phenylacetylene, poly (carbazole) diphenylacetylene, polydiacetylene, polyphenylacetylene, polypyridine acetylene, polymethoxyphenylacetylene, polymethylphenylacetylene, (Trifluoromethyl) phenylacetylene, poly (trimethylsilyl) phenylacetylene, derivatives thereof, and combinations thereof, and preferably the hole transporting material selected from the group consisting of A mixture of PEDOT and PSS.

The organic layer 20 may further include an electron transport layer (not shown) between the photoactive layer 20a and the first cathode 30a.

The electron transport layer may include any one of electron transport materials selected from the group consisting of lithium fluoride, calcium oxide, lithium oxide, titanium oxide, and combinations thereof.

On the organic layer 20, a cathode is positioned opposite to the anode 10.

The negative electrode includes a first negative electrode 30a and a second negative electrode 30b located on the first negative electrode 30b and selectively a metal mask layer 40b between the first negative electrode 30a and the second negative electrode 30b. ). ≪ / RTI >

The first cathode 30a optimizes the work function together with the second cathode 30b to maximize the efficiency of the organic solar cell and serves as a mask in patterning the organic film. The second cathode 30b serves to form a series connection between each stripe pattern in the organic solar cell module.

The cathode forming material for forming the first cathode 30a and the second cathode 30b is not particularly limited as long as it is used in an organic solar cell. However, it is possible to use a material having a low work function and high plasma resistance . Specifically, the first and second cathodes 30a and 30b may be formed as a negative electrode forming material independently of each other, such as aluminum, silver, gold, chromium, magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, Lead, stainless steel, copper, tungsten, and silicon.

The cathode forming material and the thickness of each of the first and second cathodes 30a and 30b may be suitably selected and adjusted to provide an optimal work function.

The metal mask layer 40 is located on the first cathode 30a and functions as a mask together with the first cathode 30a when patterning the organic layer 20 and also prevents the first cathode 30a from being etched . The metal mask layer 40 may be formed of noble metals such as gold or a platinum group element (ruthenium, rhodium, palladium, osmium, iridium platinum) resistant to corrosion or oxidation or a metal such as chromium . ≪ / RTI >

As described above, the organic solar cell according to the present invention includes a cathode having a multi-layered structure of a first anode and a second anode, so that organic matter is removed from a region not covered with the first anode through a dry etching process, The organic matter remaining on the surface of the substrate is removed and the current leakage due to the remaining organic matter is reduced. Also, the contact resistance between the positive electrode and the second negative electrode is reduced through cleaning of the exposed surface of the positive electrode, thereby exhibiting improved battery characteristics.

The organic solar cell having such a structure has the steps of: forming an anode (step 1); Forming an organic film including a photoactive layer on the anode (step 2); Forming a first cathode on the organic layer (Step 3); Dry-etching and patterning the organic film using the first negative electrode as a mask (step 4); And a step of forming a second cathode on the first cathode (step 5).

2 is a schematic view showing a process of manufacturing an organic solar cell according to an embodiment of the present invention. FIG. 2 is an illustration for illustrating the present invention, but the present invention is not limited thereto.

Hereinafter, a method of manufacturing an organic solar cell according to the present invention will be described in detail with reference to FIG.

Step 1 is a step of forming the anode 10 (S1).

The anode 10 may be formed according to a conventional method. Specifically, the anode 10 can be formed on one surface of the substrate 1 by having a certain pattern through a thermal vapor deposition, electron beam deposition, RF or magnetron sputtering, chemical vapor deposition or the like have.

The substrate 1 and the anode forming material are the same as described above.

Wherein at least one selected from the group consisting of O ₂ plasma treatment, UV / ozone cleaning, surface cleaning using an acid or alkali solution, nitrogen plasma treatment, and corona discharge cleaning is performed on the substrate 1, The surface of the substrate 1 may be pretreated using any one of the methods.

Step 2 is a step of forming an organic layer including the photoactive layer 20a on the anode 10 (S2).

The photoactive layer 20a may be formed by coating a composition for forming a photoactive layer prepared by dissolving the electron acceptor and the hole acceptor in a solvent by a method such as spraying, spin coating, dipping, printing, doctor blading or sputtering, Electrophoresis is performed to form a coating film of the composition for forming a photoactive layer, and then the film can be manufactured through a drying process and a heat treatment process at 25 to 150 ° C for 5 to 145 minutes. At this time, proper phase separation and orientation of the electron acceptor can be induced between the electron acceptor and the hole acceptor by appropriately controlling the process conditions in the drying step and the heat treatment step.

If the heat treatment temperature is too low or the heat treatment time is too short, the mobility of the electron acceptor and the hole acceptor may be low and the heat treatment effect may be insufficient. On the other hand, when the heat treatment temperature is excessively high or the heat treatment time is too long, There is a fear of deterioration of the receptor. Therefore, the heat treatment is preferably performed at 70 to 150 ° C for 5 to 20 minutes.

The thickness of the photoactive layer 20a formed at this time is preferably 5 to 2000 nm.

When the organic layer 20 further includes a hole transport layer 20b or an electron transport layer (not shown) in addition to the photoactive layer 20a, a hole transport material may be formed on the anode before the photoactive layer formation step (Step 2) And forming an electron transport layer including an electron transporting material on the photoactive layer before the formation of the first cathode after the formation of the photoactive layer (Step 3). .

The hole transporting layer 20b may be formed by coating the hole transporting material by a method such as spraying, spin coating, dipping, printing, doctor blading or sputtering, or electrophoresis. The thickness of the hole transport layer may preferably be 5 to 2000 nm.

The electron transfer layer (not shown) may also be formed by coating the electron transfer material by a method such as spraying, spin coating, dipping, printing, doctor blading or sputtering, or electrophoresis. The thickness of the electron transporting layer may preferably be 5 to 2000 nm.

Step 3 is a step of forming a first cathode 30a on the organic layer including the photoactive layer 20a (S3).

The first cathode 30a can be formed by screen printing a composition containing a material for forming an anode on an organic film according to a conventional method or by using a screen shadow mask such as thermal vapor deposition, electron beam evaporation, RF or magnetron sputtering, chemical vapor deposition Or a similar method.

A step of forming a metal mask layer 40 including a metal having high resistance to plasma may be further performed to prevent selective etching of the first cathode after formation of the first cathode 30a.

Specifically, the metal mask layer 40 may include a metal selected from the group consisting of chromium, gold, silver, ruthenium, rhodium, palladium, osmium, iridium, and platinum as described above. Thermal vapor deposition, electron beam deposition, RF or magnetron sputtering, chemical vapor deposition or the like.

Step 4 is a step of patterning the organic layer by dry etching the organic layer using the first cathode 30a as a mask (S4).

In the patterning process of the organic layer, a RF (Radio Frequency) voltage is applied to a chemically active gas in a low vacuum state to generate a plasma, and a reactive ion etching (Reactive Ion Etching) or plasma scribing) may be used.

The conventional wet etching method used for patterning an inorganic film or an organic film has a problem that a portion under the mask is also etched due to a chemical action by an etching solution. However, since dry etching proceeds only in the vertical direction, only the organic film is etched without damaging the first cathode 30a, the anode 10, and the metal mask layer 40 selectively included, Since the organic material does not remain after the etching, the current leakage due to the remaining organic material can be prevented. Dry etching is excellent in reproducibility and is carried out in a low vacuum state, so that it is not affected by temperature and humidity.

Specifically, the dry etching is O _2, argon _{(Ar), N 2, CHF} 3, CH 4, CF 4, SF 6, Cl 2, using the active gas that does not give a strong stimulus for the metal, such as BCl ₂ O ₂ , Ar, or N ₂ is preferable.

In the dry etching process, process conditions may vary depending on the thickness of an organic film, for example, a photoactive layer to be etched. Specifically, the dry etching is preferably performed under a pressure of 50 to 500 mTorr. The applied voltage during dry etching is preferably 50 to 1000 W.

When the organic film further includes an electron transport layer or an electron transport layer in addition to the photoactive layer, the photoactive layer and the photoactive layer may be dry-etched together when the organic film is patterned by dry etching.

Step 5 is a step of forming a second cathode 30b on the first cathode 30a (S5).

The second cathode 30b may be formed on the first cathode 30a using a shadow mask by thermal vapor deposition, electron beam evaporation, RF or magnetron sputtering, chemical vapor deposition or the like .

As described above, in the method of manufacturing an organic solar cell according to the present invention, a first negative electrode is used as a self-aligning mask without using a separate mask, and a dry etching process is performed using an anisotropic etching process It is possible to easily form a high-precision fine pattern, particularly a stripe pattern, by plasma scribing the film. In addition, residual organic matter remaining on the substrate is removed to minimize leakage of current due to remaining organic matter, thereby improving battery characteristics of the organic solar battery.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of the right.

100: Organic solar cell
1: substrate 10: anode
20: organic film 20a: photoactive layer
20b: hole transport layer 30a: first cathode
30b: second cathode 40: metal mask layer

Claims (11)

anode,
An organic layer disposed on the anode and including a photoactive layer,
A first cathode located on the organic film,
A second cathode located on the first cathode, and
A metal mask layer positioned between the first and second cathodes,
≪ / RTI > The method according to claim 1,
Wherein the organic layer includes at least one layer selected from the group consisting of a hole transporting layer located between the anode and the photoactive layer and including a hole transporting material and an electron transporting layer located between the photoactive layer and the first cathode, ≪ / RTI > delete The method according to claim 1,
Wherein the metal mask layer comprises a metal selected from the group consisting of chromium, gold, ruthenium, rhodium, palladium, osmium, iridium, and platinum. Forming an anode;
Forming an organic film including a photoactive layer on the anode;
Forming a first anode on the organic layer;
Forming a metal mask layer on the first cathode;
Patterning the organic film by dry etching using the first negative electrode as a mask; And,
Forming a second cathode on the first cathode;
Wherein the organic photovoltaic cell is a photovoltaic cell. 6. The method of claim 5,
Forming a hole transporting layer including a hole transporting material on the anode before forming the photoactive layer after the anode forming step and forming a hole transporting layer including an electron transporting material on the photoactive layer before forming the first anode after forming the photoactive layer, And forming an electron transport layer on the surface of the organic solar cell. delete 6. The method of claim 5,
Wherein the dry etching is performed by a reactive ion etching method. 6. The method of claim 5,
Wherein the dry etching is performed using an active gas selected from the group consisting of O ₂ , Ar, N ₂ , CHF ₃ , CH ₄ , CF ₄ , SF ₆ , Cl ₂ and BCl ₂ . Way. 6. The method of claim 5,
Wherein the dry etching is performed under a pressure of 50 to 500 mTorr. 6. The method of claim 5,
Wherein the dry etching is performed by applying a voltage of 50 to 1000 W.

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