KR20120060351A - Polymer solar cell and method for manufacturing the same - Google Patents

Abstract

PURPOSE: A organic solar cell and a manufacturing method thereof are provided to improve an injection property by reducing a schottky barrier between a hole transport layer and an anode or between a photoactive layer and the hole transport layer. CONSTITUTION: A cathode(160) and an anode(120) are arranged to face each other. A photoactive layer(140) is located between the cathode and the anode. The photoactive layer includes a hole receptor and an electron receptor. A hole transport layer(130) is located between the anode and the photoactive layer. Active layers(170,180) are formed for between the anode and the hole transport layer and between the hole transport layer and the photoactive layer.

Description

Organic solar cell and its manufacturing method {POLYMER SOLAR CELL AND METHOD FOR MANUFACTURING THE SAME}

The present invention relates to an organic solar cell and a method for manufacturing the same, and an organic solar cell including an active layer between an anode and a hole transport layer or between a hole transport layer and a photoactive layer and a method for manufacturing the same.

The organic solar cell is a conjugated polymer such as polyparaphenylenevinylene (PPV) having double bonds alternately and a photosensitive low molecule such as CuPc, perylene, pentacene, (6,6) -phenyl-C A solar cell having a structure utilizing an organic semiconductor material such as ₆₁ -butyric acid methyl ester (PCBM). The organic semiconductor material can be designed and synthesized in various ways, so that the organic solar cell has the potential of infinite power generation.

The organic solar cell basically has a thin film structure, and mainly uses indium tin oxide (ITO), which is a transparent electrode, as an anode, and a metal electrode such as aluminum (Al) having a low work function, as a cathode, and the photoactive layer is 100 nm. It has a bulk heterojunction structure in which a hole acceptor and an electron acceptor are mixed in a thickness of a degree.

As the hole acceptor, a conjugated polymer having the same conductivity as that of the PPV is used, and fullerene is used as the electron acceptor. In this case, fullerene must be sufficiently mixed in the conjugated polymer in order to collect electrons generated by light through the fullerene to the aluminum electrode without loss. Therefore, a fullerene derivative such as PCBM can be used to ensure that the fullerene is well mixed with the conjugated polymer. have.

When the conjugated polymer absorbs light, electron-hole pairs are generated, and the generated electrons and holes are collected at the anode and the cathode via the fullerene and the conjugated polymer, respectively.

The organic solar cell can be mass-produced at an easy processability and at an inexpensive price, and has a merit of manufacturing a large-area electronic device having flexibility because a thin film can be manufactured by a roll-to-roll method.

However, despite the technical and economic advantages as described above, due to low efficiency, there are difficulties in practical use. Therefore, researches for improving efficiency have been actively conducted in the field of organic solar cells. To date, efficiency studies have focused on the selection, fabrication, and process of photoactive layers or electron transfer layers and hole transfer layers to effectively utilize absorbed light, and to increase the morphology, structure and crystallinity of organic thin films to overcome low charge mobility. It is concentrated on the back.

An object of the present invention is to reduce the Schottky barrier between the anode and the hole transport layer or between the hole transport layer and the photoactive layer to improve the injection properties, and to form a perfect bond in forming the anode It is to provide an organic solar cell that can improve the efficiency of the organic solar cell by consuming the outermost dangling that remains on the surface without modification and preventing oxidation by modifying the surface characteristics of the anode and the hole transport layer.

Another object of the present invention is to provide a method for producing the organic solar cell.

As used herein, the term “aryl” refers to a hydrocarbon ring system having 6 to 30 carbon atoms which may be formed by the fusion of an optionally substituted benzene ring or one or more optional substituents. Examples of such optional substituents include or have substituted C _1-3 alkyl, substituted C _2-3 alkenyl, substituted C _2-3 alkynyl, heteroaryl, heterocycle, aryl, 1 to 3 fluorine substituents Alkoxy, aryloxy, aralkoxy, acyl, aroyl, heteroaroyl, acyloxy and aroyloxy. The ring or ring system may be optionally fused to an aryl ring (including benzene ring), carbocycle ring or heterocycle ring with or without one or more substituents. Examples of “aryl” include, but are not limited to, phenyl, naphthyl, tetrahydronaphthyl, biphenyl, indanyl, anthracyl, phenanthryl and substituted derivatives thereof.

As used herein, the term “heteroaryl” refers to a monocyclic 5-6 membered aromatic ring containing one or more heteroatoms selected from S, SO, SO ₂ , O, N and N-oxides, and optionally substituted, An aromatic ring (eg, a bicyclic or tricyclic ring system) fused to one or more rings, such as a heteroaryl ring, an aryl ring, a heterocycle ring, or a carbocycle ring, each having an optional substituent.

Examples of such optional substituents may or may not have substituted C _1-3 alkyl, substituted C _2-3 alkenyl, substituted C _2-3 alkynyl, heteroaryl, heterocycle, aryl, 1 to 3 fluorine substituents C _1-3 alkoxy, aryloxy, aralkoxy, acyl, aroyl, heteroaroyl, acyloxy, aroyloxy, heteroaroyloxy, sulfanyl, sulfinyl, sulfonyl, aminosulfonyl, sulfonylamino , Carboxyamide, aminocarbonyl, carboxy, oxo, hydroxy, mercapto, amino, nitro, cyano or halogen. Examples of “heteroaryl groups” as used herein include benzoimidazolyl, benzothiazolyl, benzoisothiazolyl, benzothiophenyl, benzopyrazinyl, benzotriazolyl, benzo [1,4] dioxanyl, benzo Furanyl, 9H-a-carbolinyl, cynolinyl, furanyl, puro [2,3-b] pyridinyl, imidazolyl, imidazolidinyl, imidazopyridinyl, isoxazolyl, isothia Zolyl, isoquinolinyl, indolyl, indazolyl, indolinyl, naphthyridinyl, oxazolyl, oxothiadiazolyl, oxadiazolyl, phthalazinyl, pyridyl, pyrrolyl, furinyl, putridinyl, Phenazinyl, pyrazolyl, pyrazolopyrimidinyl, pyrrolidinyl, pyridazyl, pyrazinyl, pyrimidyl, 4-oxo-1,2-dihydro-4H-pyrrolo [3,2,1-ij]- Quinolin-4-yl, quinoxalinyl, quinoxazolinyl, quinolinyl, quinolinzyl, thiophenyl, triazolyl, triazinyl, tetrazopyrimidinyl, triazolo They include, but are re-pyrimidinyl, tetrazolyl, thiazolyl, thiazolidinyl, and substituted derivatives thereof, but are not limited to:

An organic solar cell according to an embodiment of the present invention includes a cathode and an anode disposed to face each other, a photoactive layer disposed between the cathode and the anode, a hole active material and an electron acceptor mixed between the anode, the anode and the photoactive layer, An active layer formed by reacting a surface of the anode or hole transport layer with a thiol compound at at least one position between the hole transport layer including a hole transport material, and between the anode and the hole transport layer, and between the hole transport layer and the photoactive layer. It includes.

The thiol compound may be a compound of Formula 1:

[Formula 1]

R-SH

Wherein R is any one selected from the group consisting of an aryl group having 6 to 30 carbon atoms and a heteroaryl group having 3 to 30 carbon atoms, wherein R is a halogen atom, a hydroxyl group, a carboxyl group, a cyano group, a nitro group, an amine Group, thio group, nitrile group, alkyl group having 1 to 4 carbon atoms and alkoxy group having 1 to 4 carbon atoms.

R is benzoimidazolyl, benzothiazolyl, benzoisothiazolyl, benzothiophenyl, benzopyrazinyl, benzotriazolyl, benzo [1,4] dioxanyl, benzofuranyl, 9H-a-caboli Neil, cynolinyl, furanyl, furo [2,3-b] pyridinyl, imidazolyl, imidazolidinyl, imidazopyridinyl, isoxazolyl, isozozolyl, isoquinolinyl, indolyl , Indazolyl, indolinyl, naphthyridinyl, oxazolyl, oxothiadiazolyl, oxdiazolyl, phthalazinyl, pyridyl, pyrrolyl, furinyl, pteridinyl, phenazinyl, pyrazolyl, pyrazolopyripy Midinyl, pyrrolidinyl, pyridazyl, pyrazinyl, pyrimidyl, 4-oxo-1,2-dihydro-4H-pyrrolo [3,2,1-ij] -quinolin-4-yl, quinoxalinyl , Quinoxazolinyl, quinolinyl, quinolinzyl, thiophenyl, triazolyl, triazinyl, tetrazopyrimidinyl, triazolopyrimidinyl, tetrazolyl, thiazolyl, Thiazolidinyl and substituted derivatives thereof.

In addition, the thiol compound may be a compound of formula (2).

[Formula 2]

The active layer may have a thickness of 0.1 to 100 nm.

The active layer may have a surface tension of 0.5 to 60 dyne / cm.

According to the method of manufacturing an organic solar cell according to another embodiment of the present invention, forming a cathode and an anode disposed to face each other, formed between the cathode and the anode, to form a photoactive layer mixed with a hole receptor and an electron acceptor Forming a hole transport layer between the anode and the photoactive layer, the hole transport layer comprising a hole transport material, and at least one position between the anode and the hole transport layer and between the hole transport layer and the photoactive layer. Forming an active layer.

The forming of the active layer may include preparing a composition for forming an active layer by dissolving a thiol compound in an organic solvent, reacting an anode or a hole transport layer with the composition for forming an active layer, and forming the active layer on the cathode or the hole transport layer. Washing and drying the composition for forming the active layer.

The method of manufacturing the organic solar cell may further include hydrophilizing the surface of the positive electrode or the hole transport layer before the immersion process.

The hydrophilization treatment may be performed by any one selected from the group consisting of O ₂ plasma treatment, UV / ozone washing, surface washing with an acid or alkaline solution, nitrogen plasma treatment and corona discharge washing.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement 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.

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

Referring to FIG. 1, the organic solar cell 100 is positioned between the negative electrode 160 and the positive electrode 120, the negative electrode 160 and the positive electrode 120 which are disposed to face each other, and has a photoreceptor mixed with a hole acceptor and an electron acceptor. A layer 140, a hole transport layer 130 positioned between the anode 120 and the photoactive layer 140 and including a hole transport material, and between the anode 120 and the hole transport layer 130, and The active layers 170 and 180 may be included in at least one position between the hole transport layer 130 and the photoactive layer 140.

The cathode 160 and the anode 120 are positioned on the substrate 110. The substrate 110 is not particularly limited as long as it has transparency, and is a transparent inorganic substrate such as quartz or glass, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), polystyrene (PS), Polypropylene (PP), polyimide (PI), polyethylenesulfonate (PES), polyoxymethylene (POM), polyetheretherketone (PEEK), polyethersulfone (PES) and polyetherimide (PEI) Any transparent plastic substrate selected from may be used. In particular, the transparent plastic substrate may be preferably used that is flexible and has high chemical stability, mechanical strength and transparency.

The substrate 110 may have 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 120 is a path for light passing through the substrate 110 to reach the photoactive layer 140, it is preferable to use a material having high transparency, and has a high work function of about 4.5 eV or more, It is preferable to use a conductive material having a low resistance. Specific examples of the anode forming material for forming the anode 120 include tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), ZnO-Ga ₂ O ₃ , Transparent oxide selected from the group consisting of ZnO-Al ₂ O ₃ , SnO ₂ -Sb ₂ O _3, and a combination thereof, conductive polymer, graphene thin film, graphene oxide thin film, carbon nanotube An organic transparent electrode such as a thin film, an organic-inorganic bonded transparent electrode such as a carbon nanotube thin film combined with a metal, or the like may be used.

The cathode 160 is preferably made of a material having a low work function, and the cathode forming material is specifically magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, aluminum, silver, tin, lead, stainless steel, It may include any one selected from the group consisting of copper, tungsten and silicon.

The photoactive layer 140 has a bulk heterojunction structure in which a hole acceptor and an electron acceptor are mixed. The hole acceptor is an organic semiconductor, such as an electrically conductive polymer or an organic low molecular semiconductor material, and the electrically conductive polymer is polythiphene, polyphenylenevinylene, polyfulorene, polypyrrole. It may be any one selected from the group consisting of copolymers and combinations thereof, the organic low molecular weight semiconductor material is pentacene (pentacene), anthracene (anthracene), tetratrace (tetracene), perylene (perylene), Oligothiophene (oligothiphene), derivatives thereof, and combinations thereof may be any one selected from the group consisting of.

Further, the hole acceptor is preferably poly-3-hexylthiophene (P3HT), poly-3-octylthiophene (poly-3-octylthiophene, P3OT), polyparaphenylenevinylene [poly -p-phenylenevinylene, PPV], poly (dioctylfluorene) [poly (9,9'-dioctylfluorene)], poly (2-methoxy, 5- (2-ethyl-hexyloxy) -1,4- Phenylenevinylene) [poly (2-methoxy, 5- (2-ethyle-hexyloxy) -1,4-phenylenevinylene, MEH-PPV], poly (2-methyl, 5- (3 ', 7'-dimethyloctyl Oxy))-1,4-phenylenevinylene [poly (2-methyl, 5- (3 ', 7'-dimethyloctyloxy))-1,4-phenylene vinylene, MDMOPPV] and combinations thereof It can be any one.

The electron acceptor may be any one nanoparticle selected from the group consisting of fullerenes (C ₆₀ ) or fullerene derivatives, CdS, CdSe, CdTe and ZnSe. The electron acceptor is preferably (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 hole transport layer 130 may be poly (3,4-ethylenedioxythiophene) (PEDOT), poly (styrenesulfonate) (PSS), polyaniline, phthalocyanine, pentacene, polydiphenyl acetylene, poly (t-butyl ) Diphenylacetylene, poly (trifluoromethyl) diphenylacetylene, copper phthalocyanine (Cu-PC) poly (bistrifluoromethyl) acetylene, polybis (T-butyldiphenyl) acetylene, poly (trimethylsilyl) di Phenylacetylene, 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. It may include a mixture of PEDOT and PSS.

The photoactive layer 140 is preferably made of a mixture of P3HT as the hole acceptor and PCBM as the electron acceptor, wherein the mixing weight ratio of P3HT and PCBM may be 1: 0.1 to 1: 2.

The organic solar cell 100 may further include an electron transport layer 150 between the cathode 160 and the photoactive layer 140. The electron transport layer 150 may include any one electron transport material selected from the group consisting of lithium fluoride, calcium, lithium, and titanium oxide.

Meanwhile, the organic solar cell 100 has active layers 170 and 180 at at least one position between the anode 120 and the hole transport layer 130, and between the hole transport layer 130 and the photoactive layer 140. It includes.

The active layers 170 and 180 are formed by reacting a thiol compound on the surface of an anode or a hole transport layer, and an organic sulfur (organosulfur: RS-) is bonded to the surface of an anode or a hole transport layer to show an oriented structure. By forming the active layer as described above to modify the surface of the anode or hole transport layer hydrophobicly, to reduce the Schottky barrier between the anode and the hole transport layer or between the hole transport layer and the photoactive layer to improve the injection properties, anode or hole transport The oxidation of the layer can be prevented to improve the efficiency of the organic solar cell.

In addition, the active layer improves surface properties by consuming the outermost electrons remaining on the surface without being completely bonded in forming an anode. That is, when the outermost electrons are not completely bonded and remain on the surface in the formation of the anode, the electrons affect the surface characteristics, and the effects of the charge injection and the arrangement of organic materials formed thereon are affected. Will cause. Conventionally, in order to minimize such a phenomenon, a process of bonding electrons that are not bonded through a process such as surface treatment and annealing is performed, but such an additional process is unnecessary when the active layer is applied.

The thiol compound is a compound including an R moiety showing hydrophobicity and a thiol group reacting with a surface of an anode or a hole transport layer, and specifically, a compound of Formula 1 may be used:

[Formula 1]

R-SH

In the above formula, R is an aryl group having 6 to 30 carbon atoms and a heteroaryl group having 3 to 30 carbon atoms, and R is a halogen atom, a hydroxyl group, a carboxyl group, a cyano group, a nitro group, an amine group, a thio group, a nitrile group It has any one functional group selected from the group which consists of a C1-C4 alkyl group and a C1-C4 alkoxy group.

R is specifically benzoimidazolyl, benzothiazolyl, benzoisothiazolyl, benzothiophenyl, benzopyrazinyl, benzotriazolyl, benzo [1,4] dioxanyl, benzofuranyl, 9H-a- Carbolinyl, cynolinyl, furanyl, furo [2,3-b] pyridinyl, imidazolyl, imidazolidinyl, imidazopyridinyl, isoxazolyl, isothiazolyl, isoquinolinyl, Indolyl, indazolyl, indolinyl, naphthyridinyl, oxazolyl, oxothiadiazolyl, oxdiazolyl, phthalazinyl, pyridyl, pyrrolyl, furinyl, pterridinyl, phenazinyl, pyrazolyl, pyrazol Zolopyrimidinyl, pyrrolidinyl, pyridazyl, pyrazinyl, pyrimidyl, 4-oxo-1,2-dihydro-4H-pyrrolo [3,2,1-ij] -quinolin-4-yl, quinox Salinyl, quinoxazolinyl, quinolinyl, quinolininyl, thiophenyl, triazolyl, triazinyl, tetrazolopyrimidinyl, triazolopyrimidinyl, tetrazole , Thiazolyl, but may be any one selected from the group consisting of thiazolidinyl, and substituted derivatives thereof, but the invention is not limited to this.

Specific examples of the thiol compound include a compound represented by the following Chemical Formula 2:

[Formula 2]

The active layers 170 and 180 may have a thickness of about 0.1 nm to about 100 nm. When the thickness of the active layer 170 is within the above range, it is possible to effectively prevent the penetration of oxygen and moisture from the outside while improving the movement speed of the holes. In particular, when the thickness of the active layer 170 exceeds 100nm, the surface uniformity may be reduced due to the enlarging of molecules.

In addition, the active layers 170 and 180 may exhibit a surface tension of 0.5 to 60 dyne / cm. The surface tension is determined according to the hydrophobic portion. When the surface tension is within the above range, appropriate hydrophobic properties can be obtained, thereby maximizing a Schottky barrier reduction effect.

2 is a flowchart illustrating a method of manufacturing an organic solar cell according to another embodiment of the present invention, wherein the organic solar cell includes an active layer between an anode and a hole transport layer and between a hole transport layer and a photoactive layer. Hereinafter, a method of manufacturing the organic solar cell 100 will be described with reference to FIG. 2.

The anode 120 may be formed to have a predetermined pattern on one surface of the substrate 110 by thermal vapor deposition, electron beam deposition, RF or magnetron sputtering, chemical vapor deposition, or a similar method ( S10). Optionally, after forming the anode 120, the substrate 110 may be formed using any 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. ) Surface can be treated.

Next, the active layer 170 is formed on the anode 120 (S20). The active layer 170 is prepared by dissolving the thiol compound in an organic solvent to prepare a composition for forming an active layer (S21), reacting the anode with the composition for forming an active layer (S22), and forming the active layer on the anode. It can be prepared through the step (S23) for drying the composition.

In the step of preparing the active layer forming composition (S21), the active layer forming composition may be prepared by dissolving the thiol compound in an organic solvent. An alcohol-based organic solvent may be used as the organic solvent, and any one selected from the group consisting of methanol, ethanol, propanol, isopropanol, butanol, and mixtures thereof may be used as the alcohol-based organic solvent. It is not limited to this.

The thiol compound is the same as described above, the thiol compound may be included in a concentration of 1 mmol / L to 10 mol / L in the active layer forming composition. The concentration of the thiol compound determines the thickness of the active layer formed, which can form an active layer of a suitable thickness when the thiol compound is included at a concentration within the above range.

The step of reacting the positive electrode and the active layer forming composition (S22) may be performed by immersing the positive electrode in the active layer forming composition, and applying the active layer forming composition to the positive electrode or using a vapor reaction (vapor reaction). It may be.

When the positive electrode is immersed in the composition for forming an active layer, it is possible to adjust the thickness of the active layer formed on the positive electrode according to the immersion time and the number of immersion, it is preferable to carry out in a range such that the final active layer has a thickness of 0.1 to 100nm. . For example, the immersion may be performed at 20 to 40 ° C. That is, the immersion may be made at a break point (BP) at which the organic solvent of the composition for forming the active layer does not evaporate.

In addition, hydrophilization treatment is performed on the surface of the anode prior to anode immersion to improve the active layer formation efficiency and enhance interlayer adhesion by selectively removing impurities on the surface, forming an oxygen species bombardment to activate the surface. It can be carried out. The hydrophilization treatment may be carried out by O ₂ plasma treatment, UV / ozone washing, surface washing with an acid or alkaline solution, nitrogen plasma treatment, corona discharge washing and the like. In the case of performing the hydrophilization treatment by the O ₂ plasma treatment method, it is preferable that the O ₂ plasma treatment be performed within 30 seconds to prevent damage to the surface.

In the washing and drying step (S22) for the composition for forming the active layer on the positive electrode, the washing process is to remove the organic solvent in the composition for forming the active layer, and may be performed using hexane, ethanol or isopropanol, and the like. In the drying process, the surface may be dried by rotating the anode or supplying dry air or nitrogen.

Next, a hole transport layer 130 is formed on the active layer 170 (S30). The hole transport layer 130 may be coated by the method of spraying, spin coating, dipping, printing, doctor blading or sputtering, or may be formed by electrophoresis. The thickness of the hole transport layer 130 may be preferably 5 to 2000 nm.

Next, the active layer 180 is formed on the hole transport layer 130 (S40). The active layer forming process may form the active layer 180 by performing the same method as in the active layer 170 forming step (S20) described above, except that the hole transport layer is impregnated into the active layer forming composition instead of the anode.

Next, the photoactive layer 140 is formed on the active layer 180 (S50). The photoactive layer 140 is coated by a method such as spraying, spin coating, dipping, printing, doctor blading or sputtering a mixture prepared by dissolving the electron acceptor and the hole receptor in a solvent, or formed by electrophoresis can do. The photoactive layer 140 may have a thickness of about 5 nm to about 2000 nm.

The photoactive layer 140 may be manufactured through a drying process and a heat treatment process for 5 to 145 minutes at 25 to 150 ℃. By appropriately adjusting the drying process and the heat treatment process, it is possible to induce proper phase separation between the electron acceptor and the hole acceptor, and to induce orientation of the electron acceptor.

The heat treatment may be performed at 70 to 150 ° C. for 5 to 20 minutes. When the temperature is less than 70 ° C., the mobility of the electron acceptor and the hole acceptor may be low, so the heat treatment effect may be insignificant, and the heat treatment temperature may be 150 ° C. If exceeded, performance may decrease due to deterioration of the electron acceptor. In addition, when the heat treatment time is less than 5 minutes, the mobility of the electron acceptor and the hole acceptor is low, so the heat treatment effect may be insignificant, and when the heat treatment time exceeds 20 minutes, performance may decrease due to deterioration of the electron acceptor. Can be.

Optionally, the electron transport layer 150 may be formed on the photoactive layer 140 (S60). The electron transport layer 150 may be coated by the method of spraying, spin coating, dipping, printing, doctor blading or sputtering, or may be formed by electrophoresis. The thickness of the electron transport layer 150 may be preferably 5 to 2000nm.

Finally, the cathode 160 is formed by thermal vapor deposition, electron beam deposition, RF or magnetron sputtering, chemical vapor deposition, or the like on the photoactive layer 140 or the electron transport layer 150. It may be formed (S70).

Hereinafter, the operation of the organic solar cell 100 will be described briefly.

Light from an external light source is incident on the photoactive layer 140 from the anode 120. Since the substrate 110, the anode 120, and the hole transport layer 130 are all transparent, light may pass through them and be incident to the photoactive layer 140.

Photons constituting the incident light collide with electrons in the valence band present in the electron acceptor of the photoactive layer 140. Electrons in the valence band receive energy corresponding to the wavelength of the photons from the collided photons and leap to the conduction band. As electrons in the valence band leap into the conduction band, holes remain in the valence band.

The holes left in the electron acceptor move through the hole transport layer 130 to the anode 120, and electrons in the conduction band move through the electron transport layer 150 to the cathode 160. The organic solar cell 100 has electromotive force by the electrons and holes moved to each electrode to operate as a power source.

In this case, the active layers 170 and 180 consume unmatched dangling between the anode and the hole transport layer or between the hole transport layer and the photoactive layer to reduce the Schottky barrier to improve the injection properties and to prevent oxidation, thereby preventing the oxidation of the organic solar cell. The efficiency can be improved.

The organic solar cell according to the present invention reduces the Schottky barrier by consuming unmatched dangling between the anode and the hole transport layer or between the hole transport layer and the photoactive layer, thereby improving the injection properties and preventing oxidation, thereby improving the efficiency of the organic solar cell. Can improve.

1 is a perspective view illustrating an organic solar cell according to an embodiment of the present invention.
2 is a process chart showing 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 so that those skilled in the art can easily practice the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.

Preparation Example Production of Organic Solar Cell

(Example 1)

The transparent electrode patterned ITO substrate was washed with an ultrasonic cleaner, a cathode was prepared by drying using a hot air dryer, and the surface was hydrophilized by O ₂ plasma treatment at 250-150W for 10 seconds with respect to the prepared anode.

Meanwhile, 5-nitro-1H-benzo [d] imidazole-2-thiol was dissolved in ethanol at a concentration of 1 mmol to prepare a composition for forming an active layer, and the hydrophilized positive electrode prepared before the composition was immersed for 10 minutes. . The immersed positive electrode was taken out, washed with ethanol, and dried to form an active layer.

PEDOT: PSS [Poly (3,4-ethylenedioxythiophene) / poly (styrenesulfonate)] was spin coated on the active layer for 30 seconds at a speed of 4000 rpm. The coated device was dried for about 25 minutes on a 120 ° C. hot plate in a nitrogen atmosphere to form a hole transport layer.

The hole transport layer was immersed in an active layer-forming composition prepared by dissolving 5-nitro-1H-benzo [d] imidazole-2-thiol at a concentration of 1 mmol in ethanol for 10 minutes and then washed and dried to form an active layer. It was.

The P3HT: PCBM blend solution was spin-coated at 800 rpm for 30 seconds on the substrate on which the active layer was formed. At this time, the P3HT: PCBM blend solution is dissolved in the chlorobenzene solvent P3HT and PCBM with respect to the total weight of the blend solution at 25g / L and 20g / L, respectively, and mixed for 12 hours at 40 ℃ or more using a stirring magnet and vortex Prepared. After forming the P3HT: PCBM blend thin film, the solvent remaining in the thin film was removed, and a photoactive layer was prepared by drying for 1 hour or more and heating for 15 minutes in a nitrogen atmosphere at room temperature to form a crystal structure of the active layer polymer. .

After the heat treatment is completed, LiF and Al were deposited by vacuum thermal evaporation to fabricate an organic solar cell.

(Example 2)

An organic solar cell was manufactured in the same manner as in Example 1, except that the active layer was formed only on the surface of the anode.

(Example 3)

An organic solar cell was manufactured in the same manner as in Example 1, except that the active layer was formed only on the surface of the hole transport layer.

(Comparative Example 1)

An organic solar cell was manufactured in the same manner as in Example 1, except that the active layer was not formed.

Experimental Example 1

Performance Measurement of Manufactured Organic Solar Cells

The organic solar cells prepared in Examples and Comparative Examples were measured for current-voltage characteristics using a solar simulator (Newport 66984). The solar beam was used 300W xenon lamp (Newport 6258) and AM1.5G filter (Newport 81088A), the light intensity was set to 100mW / cm ² .

As a result, the organic solar cells prepared in Examples 1 to 3 showed significantly higher energy conversion efficiency, short circuit current density, and open circuit voltage than the organic solar cells prepared in Comparative Example 1. This is because the organic solar cells prepared in Examples 1 to 3 include an active layer at a position between the anode and the hole transport layer, between the hole transport layer and the photoactive layer, or both, so that the anode and the hole transport layer or between the hole transport layer and the photoactive layer are active. It is believed that this is due to the consumption of unmatched dangling between the layers, reducing the Schottky barrier to improve the implant properties and to prevent oxidation.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

100: organic solar cell
110 substrate 120 anode
130: hole transport layer 140: photoactive layer
150: electron transport layer 160: cathode
170, 180: active layer

Claims (9)

A cathode and an anode disposed opposite to each other,
Located between the cathode and the anode, a photoactive layer mixed with a hole acceptor and an electron acceptor,
A hole transport layer located between the anode and the photoactive layer and comprising a hole transport material, and
An organic solar cell comprising an active layer formed by reacting a surface of the anode or hole transport layer with a thiol compound at at least one position between the anode and the hole transport layer and between the hole transport layer and the photoactive layer. The method of claim 1,
The thiol compound is an organic solar cell that is a compound of Formula 1:
[Formula 1]
R-SH
In the above formula, R is any one selected from the group consisting of an aryl group having 6 to 30 carbon atoms and a heteroaryl group having 3 to 30 carbon atoms,
R is a functional group selected from the group consisting of a halogen atom, a hydroxyl group, a carboxyl group, a cyano group, a nitro group, an amine group, a thio group, a nitrile group, an alkyl group having 1 to 4 carbon atoms and an alkoxy group having 1 to 4 carbon atoms Has The method of claim 2,
R is benzoimidazolyl, benzothiazolyl, benzoisothiazolyl, benzothiophenyl, benzopyrazinyl, benzotriazolyl, benzo [1,4] dioxanyl, benzofuranyl, 9H-a-caboli Neil, cynolinyl, furanyl, furo [2,3-b] pyridinyl, imidazolyl, imidazolidinyl, imidazopyridinyl, isoxazolyl, isozozolyl, isoquinolinyl, indolyl , Indazolyl, indolinyl, naphthyridinyl, oxazolyl, oxothiadiazolyl, oxdiazolyl, phthalazinyl, pyridyl, pyrrolyl, furinyl, pteridinyl, phenazinyl, pyrazolyl, pyrazolopyripy Midinyl, pyrrolidinyl, pyridazyl, pyrazinyl, pyrimidyl, 4-oxo-1,2-dihydro-4H-pyrrolo [3,2,1-ij] -quinolin-4-yl, quinoxalinyl , Quinoxazolinyl, quinolinyl, quinolinzyl, thiophenyl, triazolyl, triazinyl, tetrazopyrimidinyl, triazolopyrimidinyl, tetrazolyl, thiazolyl, An organic solar cell, which is any one selected from the group consisting of thiazolidinyl and substituted derivatives thereof. The method of claim 2,
The thiol compound is an organic solar cell which is a compound of Formula 2:
(2)

The method of claim 1,
The active layer is an organic solar cell having a thickness of 0.1 to 100nm. The method of claim 1,
The active layer is an organic solar cell having a surface tension of 0.5 to 60 dyne / cm. Forming a cathode and an anode disposed to face each other,
Forming a photoactive layer between the cathode and the anode, the hole acceptor and the electron acceptor being mixed;
Forming a hole transport layer between the anode and the photoactive layer, the hole transport layer comprising a hole transport material; and
Forming an active layer at at least one position between the anode and the hole transport layer and between the hole transport layer and the photoactive layer.
Including;
Forming the active layer
Dissolving a thiol compound in an organic solvent to prepare a composition for forming an active layer,
Reacting the positive electrode or the hole transport layer with the composition for forming the active layer, and
Washing and drying the active layer forming composition on the anode or the hole transport layer
Method for producing an organic solar cell comprising a. The method of claim 7, wherein
The method of manufacturing an organic solar cell further comprising the step of hydrophilizing the surface of the positive electrode or the hole transport layer before the immersion process. The method of claim 8,
Preparation of the organic solar cell, wherein the hydrophilization treatment is carried out by any one selected from the group consisting of O ₂ plasma treatment, UV / ozone washing, surface washing with acid or alkaline solution, nitrogen plasma treatment and corona discharge washing Way.

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