KR20180010065A - Organic solar cell - Google Patents

Abstract

The present specification relates to an organic solar cell. The organic solar cell includes a first electrode, a second electrode facing the first electrode, and one or more organic material layers including a photoactive layer disposed between the first electrode and the second electrode. Accordingly, the present invention can easily control the entire solar absorption wavelength region by introducing a ternary system into the photoactive layer.

Description

Organic solar cell {ORGANIC SOLAR CELL}

The present disclosure relates to organic solar cells.

Organic solar cells are devices that can convert solar energy directly into electric energy by applying photovoltaic effect. Solar cells can be divided into inorganic solar cells and organic solar cells depending on the material constituting the thin film. A typical solar cell is made of p-n junction by doping crystalline silicon (Si), which is an inorganic semiconductor. Electrons and holes generated by absorption of light are diffused to the p-n junction, accelerated by the electric field, and moved to the electrode. The power conversion efficiency of this process is defined as the ratio of the power given to the external circuit to the solar power entering the solar cell, and is achieved up to 24% when measured under the current standardized virtual solar irradiation conditions. However, since conventional inorganic solar cells have already been limited in economic efficiency and supply / demand of materials, organic semiconductor solar cells, which are easy to process, have various functions and are inexpensive, are seen as long-term alternative energy sources.

Solar cells are important to increase efficiency so that they can output as much electrical energy as possible from solar energy. In order to increase the efficiency of such a solar cell, it is also important to generate as much excitons as possible in the semiconductor, but it is also important to draw out generated charges without loss. One of the causes of loss of charge is that the generated electrons and holes are destroyed by recombination. Various methods have been proposed as methods for transferring generated electrons and holes to electrodes without loss, but most of them require additional processing, which may increase the manufacturing cost.

Korean Patent Laid-Open Publication No. 2014-0025621

Two-layer organic photovoltaic cells (C. W. Tang, Appl. Phys. Lett., 48, 183. (1996) Yu, J. Gao, J. C. Hummelen, F. Wudl, A. J. Heeger, Science, 270, 1789. (1995)).

It is an object of the present invention to provide an organic solar cell.

According to one embodiment of the present disclosure, there is provided a liquid crystal display comprising: a first electrode; A second electrode facing the first electrode; And a photoactive layer disposed between the first electrode and the second electrode, wherein the photoactive layer includes a unit represented by the following formula (1); A polymer comprising a unit represented by the following formula (2); And an electron acceptor material, wherein the unit represented by the formula (1) and the unit represented by the formula (2) are different from each other.

[Chemical Formula 1]

(2)

In the above formulas (1) and (2)

X1 to X3 and X11 to X13 are the same or different from each other and each independently CRR ', NR, O, SiRR', PR, S, GeRR '

Y1, Y2, Y11 and Y12 are the same or different and are each independently CR ", N, SiR", P or GeR "

A substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkoxy group, An unsubstituted aryl group or a substituted or unsubstituted heterocyclic group,

n1, n2, n11 and n12 are each an integer of 1 or more,

When n1, n2, n11 and n12 are each 2 or more, the structures in the parentheses of 2 or more are the same or different,

m1 and m11 are the number of repeating units and are an integer of 1 to 10,000, respectively.

In the organic solar cell according to one embodiment of the present invention, the ternary system is introduced into the photoactive layer, and the entire region of the solar absorption wavelength can be easily controlled.

The organic solar cell according to one embodiment of the present invention includes one kind of electron donor material in the photoactive layer and two similar electron donor materials having a similar backbone, , And a polymer containing the unit represented by the formula (2), it is possible to control the energy structure of two different electron donor materials having mutually complementary absorption band bands and to control the chemical and physical properties By reducing the difference and increasing the molecular alignment like a molecule, it can be aligned with the same crystal structure.

In addition, the two electron donor materials can induce the formation of one-phase crystalline domains in bulk morphology. In addition, two kinds of electron donor materials having well-aligned energy levels can lower the probability of electron-hole recombination and simultaneously increase charge separation and migration. Accordingly, as the ternary blend system is introduced into the photoactive layer, the open current can be increased, the open voltage can be controlled, and the charge recombination can be reduced, thereby providing a highly efficient organic solar cell.

1 is a view illustrating an organic solar cell according to an embodiment of the present invention.
2 is a graph showing an energy level of an organic solar cell according to an embodiment of the present invention.
FIG. 3 is a diagram showing a UV-vis absorption spectrum of a polymer containing a unit represented by the formula 1-3 and a polymer containing a unit represented by the formula 2-3. FIG.
4 shows a polymer (X) containing a unit represented by the above formula (1-3): a polymer (Y) comprising a unit represented by the above formula (2-3): PC ₇₀ BM Of the UV-vis absorption spectrum.

Hereinafter, the present invention will be described in more detail.

As used herein, the term 'unit' means a structure in which a monomer is included in a polymer, and the monomer is bonded to the polymer by polymerization.

In this specification, the meaning of 'including unit' means that it is included in the main chain in the polymer.

Whenever a component is referred to as "comprising ", it is understood that it may include other components as well, without departing from the other components unless specifically stated otherwise.

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.

The organic solar cell according to one embodiment of the present invention includes a polymer including a unit represented by the formula (1) in the photoactive layer; And a polymer having units having a substituent and containing a main chain similar to the unit represented by the formula (1) but having a different substituent and having a low band gap, the polymer comprising a unit represented by the formula (2) as an electron donor, system.

The organic solar cell may further include a polymer including a unit represented by Formula 1 in the photoactive layer; And a polymer including units having the same structure as the unit represented by the formula (1) but having a different substituent group and having a low band gap as the electron donor, thereby increasing the solar absorption region At the same time, the nano-fibrillar film of the existing binary system can be maintained.

Illustrative examples of such substituents are set forth below, but are not limited thereto.

The term "substituted" means that the hydrogen atom bonded to the carbon atom of the compound is replaced with another substituent, and the substituted position is not limited as long as the substituent is a substitutable position, , Two or more substituents may be the same as or different from each other.

As used herein, the term " substituted or unsubstituted " A halogen group; A nitrile group; A nitro group; Imide; Amide group; A hydroxy group; A substituted or unsubstituted alkyl group; A substituted or unsubstituted cycloalkyl group; A substituted or unsubstituted alkoxy group; A substituted or unsubstituted aryloxy group; A substituted or unsubstituted alkylthio group; A substituted or unsubstituted arylthio group; A substituted or unsubstituted alkylsulfoxy group; A substituted or unsubstituted arylsulfoxy group; A substituted or unsubstituted alkenyl group; A substituted or unsubstituted aryl group; And a substituted or unsubstituted heterocyclic group, or two or more of the substituents exemplified above are substituted with a substituent to which they are linked, or have no substituent. For example, the "substituent group to which two or more substituents are connected" may be a biphenyl group. That is, the biphenyl group may be an aryl group, and may be interpreted as a substituent in which two phenyl groups are connected.

In the present specification, the number of carbon atoms in the imide group is not particularly limited, but is preferably 1 to 30 carbon atoms. Specifically, it may be a compound having the following structure, but is not limited thereto.

In the present specification, the amide group may be mono- or di-substituted with nitrogen of the amide group with hydrogen, a straight-chain, branched or cyclic alkyl group having 1 to 30 carbon atoms or an aryl group having 6 to 30 carbon atoms. Specifically, it may be a compound of the following structural formula, but is not limited thereto.

In the present specification, examples of the halogen group include fluorine, chlorine, bromine or iodine.

In the present specification, the alkyl group may be linear or branched, and the number of carbon atoms is not particularly limited, but is preferably 1 to 50. Specific examples include methyl, ethyl, propyl, n-propyl, isopropyl, butyl, n-butyl, isobutyl, tert-butyl, sec- N-pentyl, 3-dimethylbutyl, 2-ethylbutyl, heptyl, n-hexyl, Cyclohexylmethyl, octyl, n-octyl, tert-octyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, n-nonyl, 2,2-dimethyl Heptyl, 1-ethyl-propyl, 1,1-dimethyl-propyl, isohexyl, 2-methylpentyl, 4-methylhexyl, 5-methylhexyl and the like.

In the present specification, the cycloalkyl group is not particularly limited, but preferably has 3 to 60 carbon atoms. Specific examples thereof include cyclopropyl, cyclobutyl, cyclopentyl, 3-methylcyclopentyl, 2,3-dimethylcyclopentyl, But are not limited to, 3-methylcyclohexyl, 4-methylcyclohexyl, 2,3-dimethylcyclohexyl, 3,4,5-trimethylcyclohexyl, 4-tert- butylcyclohexyl, cycloheptyl, Do not.

In the present specification, the alkoxy group may be linear, branched or cyclic. The number of carbon atoms of the alkoxy group is not particularly limited, but is preferably 1 to 20 carbon atoms. Specific examples include methoxy, ethoxy, n-propoxy, isopropoxy, i-propyloxy, n-butoxy, isobutoxy, tert-butoxy, sec-butoxy, n-pentyloxy, neopentyloxy, N-hexyloxy, n-hexyloxy, 3,3-dimethylbutyloxy, 2-ethylbutyloxy, n-octyloxy, n-nonyloxy, n-decyloxy, benzyloxy, But is not limited thereto.

In the present specification, the alkenyl group may be straight-chain or branched, and the number of carbon atoms is not particularly limited, but is preferably 2 to 40. Specific examples include vinyl, 1-propenyl, isopropenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-pentenyl, Butenyl, allyl, 1-phenylvinyl-1-yl, 2-phenylvinyl-1-yl, (Diphenyl-1-yl) vinyl-1-yl, stilbenyl, stilenyl, and the like.

In the present specification, when the aryl group is a monocyclic aryl group, the number of carbon atoms is not particularly limited, but is preferably 6 to 25 carbon atoms. Specific examples of the monocyclic aryl group include a phenyl group, a biphenyl group, a terphenyl group, and the like, but are not limited thereto.

In the present specification, when the aryl group is a polycyclic aryl group, the number of carbon atoms is not particularly limited. And preferably has 10 to 24 carbon atoms. Specific examples of the polycyclic aryl group include naphthyl, anthracenyl, phenanthryl, pyrenyl, perylenyl, klychenyl, fluorenyl, and the like.

In the present specification, the fluorenyl group may be substituted, and adjacent substituents may be bonded to each other to form a ring.

,

,

,

,

,

,

및

등이 될 수 있다. 다만, 이에 한정되는 것은 아니다.When the fluorenyl group is substituted,

,

,

,

,

,

,

And

And the like. However, the present invention is not limited thereto.

In the present specification, the heterocyclic group includes at least one non-carbon atom or hetero atom, and specifically, the hetero atom may include at least one atom selected from the group consisting of O, N, Si, Se, and S have. The number of carbon atoms of the heterocyclic group is not particularly limited, but is preferably 2 to 60 carbon atoms. Examples of the heterocyclic group include a thiophene group, a furane group, a furyl group, an imidazole group, a thiazole group, an oxazole group, an oxadiazole group, a triazole group, a pyridyl group, a bipyridyl group, a pyrimidyl group, A pyridazinyl group, a pyrazinopyrazinyl group, an isoquinoline group, a pyrazinyl group, a pyrazinyl group, a pyrazinyl group, a pyrazinyl group, a quinolinyl group, a quinazolinyl group, a quinoxalinyl group, a phthalazinyl group, a pyridopyrimidinyl group, A benzothiazole group, a benzothiophene group, a dibenzothiophene group, a benzofuranyl group, a phenanthroline group, a thiazolyl group, a thiazolyl group, a thiazolyl group, An isoxazolyl group, an oxadiazolyl group, a thiadiazolyl group, a benzothiazolyl group, a phenothiazinyl group, and a dibenzofuranyl group, but is not limited thereto.

In the present specification, the number of carbon atoms of the amine group is not particularly limited, but is preferably 1 to 30. The amine group may be substituted on the N atom with an aryl group, an alkyl group, an arylalkyl group, and a heterocyclic group. Specific examples of the amine group include a methylamine group, a dimethylamine group, an ethylamine group, a diethylamine group, A phenol group, a naphthylamine group, a biphenylamine group, an anthracenylamine group, a 9-methyl-anthracenylamine group, a diphenylamine group, a phenylnaphthylamine group, a ditolylamine group, a phenyltolylamine group, And the like, but the present invention is not limited thereto.

In the present specification, the aryl group in the aryloxy group, the arylthioxy group and the arylsulfoxy group is the same as the aforementioned aryl group. Specific examples of the aryloxy group include phenoxy, p-tolyloxy, m-tolyloxy, 3,5-dimethyl-phenoxy, 2,4,6-trimethylphenoxy, Naphthyloxy, 4-methyl-1-naphthyloxy, 5-methyl-2-naphthyloxy, 1-anthryloxy, 2-anthryl Phenanthryloxy, 9-phenanthryloxy and the like. Examples of the arylthioxy group include phenylthio group, 2-methylphenylthio group, 4-tert-butylphenyl And the like. Examples of the aryl sulfoxy group include a benzene sulfoxy group and a p-toluenesulfoxy group. However, the present invention is not limited thereto.

In the present specification, the alkyl group in the alkylthio group and alkylsulfoxy group is the same as the alkyl group described above. Specific examples of the alkyloxy group include a methylthio group, an ethylthio group, a tert-butylthio group, a hexylthio group and an octylthio group. Examples of the alkylsulfoxy group include a mesyl group, an ethylsulfoxy group, a propylsulfoxy group, But are not limited thereto.

According to one embodiment of the present invention, X1 to X3 in Formula 1 are S.

According to one embodiment of the present invention, in the formula (1), Y1 and Y2 are N.

According to one embodiment of the present invention, the unit represented by the formula (1) is represented by the following formula (1-1).

[Formula 1-1]

In Formula 1-1,

The definitions of R1 to R10, n1, n2 and m1 are the same as those in the above formula (1).

According to one embodiment of the present invention, in the general formula (1), R1 to R10 are the same or different from each other, and each independently hydrogen; A halogen group; Or an alkoxy group.

According to one embodiment of the present invention, in the general formula (1), R1 to R10 are the same or different and each independently hydrogen; Fluorine; Or a branched alkoxy group.

According to one embodiment of the present invention, in the general formula (1), R1 to R10 are the same or different and each independently hydrogen; Fluorine; Or a 2-hexyldecyloxy group.

According to one embodiment of the present invention, the unit represented by the formula (1) is represented by the following formula (1-2).

[Formula 1-2]

In Formula 1-2,

R6, R7, R9, R10, n1, n2 and m1 are as defined in the above formula (1).

According to one embodiment of the present invention, in Formula 1, R6 and R7 are the same or different and each independently an alkoxy group.

According to one embodiment of the present invention, R6 and R7 are the same or different and independently of each other are a branched alkoxy group.

According to one embodiment of the present invention, in the above formula (1), R6 and R7 are 2-hexyldecyloxy group.

According to one embodiment of the present invention, in the general formula (1), R9 and R10 are the same or different and are each independently a halogen group.

According to one embodiment of the present invention, in the above formula (1), R9 and R10 are fluorine.

According to one embodiment of the present invention, in the above formula (1), n1 and n2 are each 1 or 2.

According to one embodiment of the present invention, in the above formula (1), n1 and n2 are 1.

According to one embodiment of the present invention, the unit represented by the formula (1) is represented by the following formula (1-3).

[Formula 1-3]

In Formula 1-3,

The definition of m1 is the same as in the above formula (1).

According to one embodiment of the present invention, in the general formula (2), X11 to X13 are S.

According to one embodiment of the present invention, in the above formula (2), Y 11 and Y 12 are N.

According to one embodiment of the present invention, the unit represented by the formula (2) is represented by the following formula (2-1).

[Formula 2-1]

In Formula 2-1,

The definitions of R11 to R20, n11, n12 and m11 are the same as those of the above formula (2).

According to one embodiment of the present invention, in the general formula (2), R11 to R20 are the same or different and each independently hydrogen; A nitrile group; Or an alkoxy group.

According to one embodiment of the present invention, in Formula 2, R11 to R20 are the same or different and each independently hydrogen; A nitrile group; Or a branched alkoxy group.

According to one embodiment of the present invention, in Formula 2, R11 to R20 are the same or different and each independently hydrogen; A nitrile group; Or a 2-decyltetradecyloxy group.

According to one embodiment of the present invention, the unit represented by the formula (2) is represented by the following formula (2-2).

[Formula 2-2]

According to one embodiment of the present invention, in the general formula (2), R16 and R17 are the same or different and each independently an alkoxy group.

According to one embodiment of the present invention, in the general formula (2), R16 and R17 are the same or different and each independently represents a branched chain alkoxy group.

According to one embodiment of the present invention, in the above formula (2), R16 and R17 are 2-decyltetradecyloxy group.

According to one embodiment of the present invention, in the general formula (2), R19 and R20 are the same or different and each independently a nitrile group.

According to one embodiment of the present invention, in the above formula (2), n11 and n12 are each 1 or 2.

According to one embodiment of the present invention, in the above formula (2), n11 and n12 are 1.

According to one embodiment of the present invention, the unit represented by the formula (2) is represented by the following formula (2-3).

[Formula 2-3]

In Formula 2-3,

The definition of m11 is the same as in the above formula (2).

According to one embodiment of the present invention, the unit represented by Formula 1 and the unit represented by Formula 2 are different from each other.

According to one embodiment of the present invention, the polymer containing the unit represented by the formula (1) and the polymer containing the unit represented by the formula (2) each have a solubility in chlorobenzene of 0.1 wt% to 20 wt% 0.1 wt% to 5 wt%. The solubility measurement may refer to a value measured at room temperature.

According to one embodiment of the present invention, the end groups of the polymer containing the unit represented by the formula (1) and the polymer containing the unit represented by the formula (2) are respectively trifluoro-benzene group and / 4-Bromodiphenyl ether is used, but generally known end groups can be used according to the needs of the person skilled in the art, but it is not limited thereto.

According to one embodiment of the present invention, the number average molecular weight of the polymer containing the unit represented by the formula (1) and the polymer containing the unit represented by the formula (2) is preferably 5,000 g / mol to 1,000,000 g / mol, , More preferably from 5,000 g / mol to 100,000 g / mol.

According to one embodiment of the present invention, the polymer having the unit represented by the formula (1) and the polymer containing the unit represented by the formula (2) may have a molecular weight distribution of 1 to 10, respectively. Preferably a molecular weight distribution of from 1 to 3.

In addition, the number average molecular weight is preferably 100,000 g / mol or less in order to have a solubility of more than a certain level and to be advantageous in application of a solution coating method.

The polymer containing the unit represented by the formula (1) and the polymer containing the unit represented by the formula (2) according to the present invention can be prepared by a multistage chemical reaction. The monomers are produced through an alkylation reaction, a Grignard reaction, a Suzuki coupling reaction, a Stille coupling reaction, and the like, followed by a carbon-carbon coupling reaction such as a steel coupling reaction, . ≪ / RTI > When the substituent to be introduced is a boronic acid or a boronic ester compound, it can be prepared through a Suzuki coupling reaction. When the substituent to be introduced is tributyltin or trimethyltin ) Compound, it may be prepared through a steel coupling reaction, but the present invention is not limited thereto.

An organic solar cell according to an embodiment of the present invention includes a first electrode, a photoactive layer, and a second electrode. The organic solar cell may further include a substrate, a hole transporting layer, and / or an electron transporting layer.

According to one embodiment of the present invention, when the organic solar cell receives photons from an external light source, electrons and holes are generated between the electron beams and the electron acceptors. The generated holes are transported to the anode through the electron donor layer.

According to one embodiment of the present invention, the electron donor is a polymer comprising a unit represented by the formula (1) and a polymer represented by the formula (2).

1 illustrates an organic solar cell according to an embodiment of the present invention.

According to one embodiment of the present invention, when the organic solar cell receives photons from an external light source, electrons and holes are generated between the electron beams and the electron acceptors. The generated holes are transported to the anode through the electron donor layer.

According to one embodiment of the present disclosure, the organic solar cell may further include an additional organic layer. The organic solar cell can reduce the number of organic layers by using organic materials having various functions at the same time.

According to one embodiment of the present disclosure, the first electrode is an anode and the second electrode is a cathode. According to another embodiment, the first electrode is a cathode and the second electrode is an anode.

According to one embodiment of the present disclosure, the organic solar cell may be arranged in the order of the cathode, the photoactive layer, and the anode, and may be arranged in the order of the anode, the photoactive layer, and the cathode.

According to another embodiment, the organic solar cell may be arranged in the order of an anode, a hole transporting layer, a photoactive layer, an electron transporting layer and a cathode, and may be arranged in the order of a cathode, an electron transporting layer, a photoactive layer, a hole transporting layer, , But is not limited thereto.

According to one embodiment of the present invention, the organic solar cell has a normal structure. The normal structure may mean that the anode is formed on the substrate. Specifically, according to an embodiment of the present invention, when the organic solar cell is a normal structure, the first electrode formed on the substrate may be an anode.

According to one embodiment of the present invention, the organic solar cell is an inverted structure. The inverted structure may mean that the cathode is formed on the substrate. Specifically, according to one embodiment of the present disclosure, when the organic solar cell is an inverted structure, the first electrode formed on the substrate may be a cathode.

According to one embodiment of the present invention, the organic solar cell is a tandem structure. In this case, the organic solar cell may include two or more photoactive layers. The organic solar cell according to one embodiment of the present disclosure may have one photoactive layer or two or more layers.

According to another embodiment, a buffer layer may be provided between the photoactive layer and the hole transporting layer or between the photoactive layer and the electron transporting layer. At this time, a hole injection layer may be further provided between the anode and the hole transport layer. Further, an electron injecting layer may be further provided between the cathode and the electron transporting layer.

According to one embodiment of the present invention, the photoactive layer includes one or more selected from the group consisting of an electron donor and a donor, and the electron donor comprises a polymer including a unit represented by the formula (1) Lt; / RTI >

According to one embodiment of the present invention, the electron acceptor material is one or two or more compounds selected from the group consisting of fullerene, fullerene derivatives, vasocopherin, semiconductor elements, and semiconducting compounds. Specifically, fullerene, fullerene derivatives (PC ₆₁ BM (6,6) -phenyl-C ₆₁ -butyric acid-methylester), PC ₇₁ BM ((6,6) -phenyl-C ₇₁ -butyric acid- PC ₆₀ BM ((6,6) -phenyl-C70-butyric acid-methylester), or PC ₆₁ BCR ((6,6) -phenyl-C61-butyric acid-cholesteryl ester), perylene PBI (polybenzimidazole ), And PTCBI (3,4,9,10-perylene-tetracarboxylic bis-benzimidazole).

The organic solar cell according to one embodiment of the present invention includes one kind of electron donor material in the photoactive layer and two kinds of electron donor materials having a similar backbone, And the polymer containing the unit represented by the formula (2), it is possible to control the energy structure of two different electron donor materials having mutually complementary absorption band bands, And can be aligned with the same crystal structure by increasing molecular alignment like a molecule.

In addition, the two electron donor materials can induce the formation of one-phase crystalline domains in bulk morphology. In addition, two kinds of electron donor materials having well-aligned energy levels can lower the probability of electron-hole recombination and simultaneously increase charge separation and migration. Accordingly, as the ternary blend system is introduced into the photoactive layer, the open current can be increased, the open voltage can be controlled, and the charge recombination can be reduced, thereby providing a highly efficient organic solar cell.

According to one embodiment of the present invention, the polymer comprising the unit represented by the formula (1): the polymer comprising the unit represented by the formula (2): the electron acceptor material has a composition of 0.01 to 0.99: 0.01 to 0.99: 0.5 to 5 Mass ratio, and preferably in a mass ratio of 0.1 to 0.9: 0.1 to 0.9: 1.5.

When the polymer including the unit represented by the formula (1), the polymer including the unit represented by the formula (2), and the electron acceptor material are contained in the mass ratio, two different electron donors By controlling the energy structure of the material, it is possible to reduce the difference in chemical and physical properties, to increase the molecular alignment as one molecule, and to align with the same crystal structure. In addition, the two electron donor materials can induce the formation of one-phase crystalline domains in bulk morphology. In addition, two kinds of electron donor materials having well-aligned energy levels can lower the probability of electron-hole recombination and simultaneously increase charge separation and migration. Accordingly, as the ternary blend system is introduced into the photoactive layer, the open current can be increased, the open voltage can be controlled, and the charge recombination can be reduced, thereby providing a highly efficient organic solar cell.

According to one embodiment of the present disclosure, the electron donor and the electron acceptor constitute a bulk heterojunction (BHJ).

According to one embodiment of the present invention, the polymer comprising the unit represented by the formula (1), the polymer including the unit represented by the formula (2), and the electron acceptor material constitute a bulk heterojunction (BHJ).

Bulk heterojunction means that the electron donor material and the electron acceptor material are mixed in the photoactive layer.

According to one embodiment of the present disclosure, the photoactive layer further comprises an additive.

The additive includes 1 to 5% by weight based on the entire photoactive layer. When the additive is contained in an amount of 1 to 5% by weight, the solubility of the polymer including the unit represented by the formula (1) and the unit containing the unit represented by the formula (2) An effective phase separation induced by a difference in boiling point can be induced. In addition, it is possible to prevent the phase separation from occurring by fixing the morphology by crosslinking the electron acceptor material or the electron donor material, and the morphology can be controlled by changing the molecular structure of the electron donor material.

According to one embodiment of the present disclosure, the molecular weight of the additive is from 50 g / mol to 1000 g / mol.

According to another embodiment, the boiling point of the additive is from 30 to 300 organics.

In this specification, an organic substance means a substance containing at least one carbon atom.

According to one embodiment, the additive is selected from the group consisting of 1,8-diiodooctane (DIO), 1-chloronaphthalene (1-CN), diphenylether One or two additives among additives selected from the group consisting of octane dithiol, tetrabromothiophene, and the like.

For the efficient separation of excitons from organic solar cells and the effective transport of separated charges, the interface between the electron and the donor is maximized, ensuring continuous passage of the electrons and the acceptor through appropriate phase separation and inducing the improvement of morphology .

According to one embodiment of the present invention, by introducing the additive into the active layer, the solubility and the solubility of the polymer including the unit represented by the formula (1) and the polymer containing the unit represented by the formula (2) And an effective phase separation induced by the boiling point difference of the additive. In addition, it is possible to prevent the phase separation from occurring by fixing the morphology by crosslinking the electron acceptor material or the electron donor material, and the morphology can be controlled by changing the molecular structure of the electron donor material.

In addition, morphology can be improved through post-treatment such as heat treatment at high temperature as well as improvement of morphology through control of the stereoregularity of the electron donor material. This can lead to the orientation and crystallization of the polymer according to one embodiment of the present disclosure, and can increase the roughness of the photoactive layer, facilitating contact with the electrode and inducing effective charge transfer.

According to one embodiment of the present invention, the photoactive layer is a bilayer structure including an n-type organic layer and a p-type organic layer, and the p-type organic layer includes the polymer.

In this specification, the substrate may be a glass substrate or a transparent plastic substrate having excellent transparency, surface smoothness, ease of handling, and waterproofness, but is not limited thereto, and is not limited as long as it is a substrate commonly used in organic solar cells. Specific examples include glass or polyethylene terephthalate, polyethylene naphthalate (PEN), polypropylene (PP), polyimide (PI), and triacetyl cellulose (TAC) But is not limited thereto.

The anode electrode may be a transparent material having excellent conductivity, but is not limited thereto. Metals such as vanadium, chromium, copper, zinc, and gold, or alloys thereof; Metal oxides such as zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO); ZnO: Al or SnO _2: a combination of a metal and an oxide such as Sb; Conductive polymers such as poly (3-methylthiophene), poly [3,4- (ethylene-1,2-dioxy) thiophene] (PEDOT), polypyrrole and polyaniline.

The method of forming the anode electrode is not particularly limited and may be applied to one surface of the substrate or may be coated in a film form using, for example, sputtering, E-beam, thermal evaporation, spin coating, screen printing, inkjet printing, doctor blade or gravure printing . ≪ / RTI >

When the anode electrode is formed on a substrate, it may undergo cleaning, moisture removal and hydrophilic reforming processes.

For example, the patterned ITO substrate is sequentially cleaned with a detergent, acetone, and isopropyl alcohol (IPA), and then dried on a heating plate at 100 to 150 ° C. for 1 to 30 minutes, preferably 120 to 10 minutes, Is completely cleaned, the substrate surface is modified to be hydrophilic.

Through such surface modification, the junction surface potential can be maintained at a level suitable for the surface potential of the photoactive layer. Further, in the modification, the formation of the polymer thin film on the anode electrode is facilitated, and the quality of the thin film may be improved.

The anode electrode pre-treatment techniques include a) surface oxidation using a parallel plate discharge, b) a method of oxidizing the surface through ozone generated using UV ultraviolet radiation in vacuum, and c) oxygen radicals produced by the plasma And the like.

One of the above methods can be selected depending on the state of the anode electrode or the substrate. However, whichever method is used, it is preferable to prevent oxygen from escaping from the surface of the anode electrode or the substrate and to suppress the residual of moisture and organic matter as much as possible. At this time, the substantial effect of the preprocessing can be maximized.

As a specific example, a method of oxidizing the surface through ozone generated using UV can be used. At this time, the ITO substrate patterned after the ultrasonic cleaning is baked on a hot plate, dried well, then put into a chamber, and is irradiated with ozone generated by reaction of oxygen gas with UV light by operating a UV lamp The patterned ITO substrate can be cleaned.

However, the method of modifying the surface of the patterned ITO substrate in the present specification is not particularly limited, and any method may be used as long as it is a method of oxidizing the substrate.

The cathode electrode may be a metal having a small work function, but is not limited thereto. Specifically, metals such as magnesium, calcium, sodium, potassium, titanium, indium, yttrium, lithium, gadolinium, aluminum, silver, tin and lead or alloys thereof; Layer structure such as LiF / Al, LiO ₂ / Al, LiF / Fe, Al: Li, Al: BaF ₂ and Al: BaF ₂ : Ba.

The cathode may be deposited in a thermal evaporator having a degree of vacuum of 5 x 10 ^{< -7} > torr or less, but the method is not limited thereto.

The hole transporting layer and / or the electron transporting layer material efficiently transfer electrons and holes separated from the photoactive layer to the electrode, and the material is not particularly limited.

The hole transport layer material may include PEDOT: PSS (poly (3,4-ethylenedioxythiophene) -poly (styrenesulfonate)), molybdenum oxide (MoO _x ); Vanadium oxide (V ₂ O ₅ ); Nickel oxide (NiO); And tungsten oxide (WO _x ), but the present invention is not limited thereto.

The electron transport layer material may be electron-extracting metal oxides, specifically a metal complex of 8-hydroxyquinoline; Complexes containing Alq ₃ ; Metal complexes including Liq; LiF; Ca; Titanium oxide (TiO _x ); Zinc oxide (ZnO); And cesium carbonate (Cs ₂ CO ₃ ), polyethyleneimine (PEI), and the like, but are not limited thereto.

The photoactive layer can be formed by dissolving a photoactive material such as an electron donor and / or an electron acceptor in an organic solvent, and then applying the solution by spin coating, dip coating, screen printing, spray coating, doctor blade, brush painting, But is not limited to the method.

Hereinafter, the present invention will be described in detail by way of examples with reference to the drawings. However, the embodiments according to the present disclosure can be modified in various other forms, and the scope of the present specification is not construed as being limited to the embodiments described below. Embodiments of the present disclosure are provided to more fully describe the present disclosure to those of ordinary skill in the art.

Experimental Example 1. Preparation of Organic Solar Cell

A polymer containing units represented by the above Chemical Formulas 1-3 and a polymer containing units represented by Chemical Formula 2-3 and a PC ₇₀ BM were mixed in a mass ratio of 0.9: 0.1: 1.5 at a ratio of chlorobenzene: diphenyl ether ether, CB: DPE = 97: 3 (v / v)) to prepare a composite solution. At this time, the polymer concentration was adjusted to 1.2 wt%, and the organic solar cell had the structure of ITO / PEDOT: PSS / photoactive layer / Al. A 1.5 × 1.5 cm ² glass substrate coated with ITO bar type (1.0 × 1.5 cm ² ) was ultrasonically cleaned in the order of distilled water, acetone, and 2-propanol and dried for one day. The ITO surface was ozone treated for 20 minutes and then 40 nm thick PEDOT: PSS (AI4083) was spin coated at 4000 rpm for 40-60 seconds and heat treated at 140 for 10 minutes. PEODT: Polymer containing the unit represented by the above formula (1-3) on the PSS layer: Polymer having the unit represented by the formula (2-3): PC ₇₀ BM composite solution was spin-coated at 1,000 rpm for 60 seconds to form 250-300 nm thick photoactive layer. An organic solar cell was fabricated by depositing Al with a thickness of 100 nm at a rate of 1 Å / s under a vacuum of 10 -6 Torr or less using a thermal evaporator.

Experimental Example 2. Preparation of Organic Solar Cell

In the same manner as in Experimental Example 1, except that the polymer containing the unit represented by the formula 1-3 and the polymer containing the unit represented by the formula 2-3 and the PC ₇₀ BM were changed to 0.7: 0.3: 1.5 An organic solar cell was prepared.

Experimental Example 3. Preparation of Organic Solar Cell

In the same manner as in Experimental Example 1, except that the polymer containing the unit represented by the formula 1-3 and the polymer containing the unit represented by the formula 2-3 and the PC ₇₀ BM were changed to 0.5: 0.5: 1.5 An organic solar cell was prepared.

Experimental Example 4. Preparation of Organic Solar Cell

In the same manner as in Experimental Example 1, except that the polymer containing the unit represented by the formula 1-3 and the polymer containing the unit represented by the formula 2-3 were replaced by PC ₇₀ BM in a ratio of 0.3: 0.7: 1.5 An organic solar cell was prepared.

Experimental Example 5. Preparation of Organic Solar Cell

In the same manner as in Experimental Example 1, except that the polymer containing the unit represented by Formula 1-3 and the polymer comprising the unit represented by Formula 2-3 and PC ₇₀ BM were used in a ratio of 0.1: 0.9: 1.5 An organic solar cell was prepared.

Comparative Example 1. Preparation of Organic Solar Cell

In the same manner as in Experimental Example 1, except that the polymer containing the unit represented by the formula 1-3 and the polymer containing the unit represented by the formula 2-3 and the PC ₇₀ BM were changed to 1: 0: 1.5 An organic solar cell was prepared.

Comparative Example 2: Production of organic solar cell

In the same manner as in Experimental Example 1, except that the polymer containing the unit represented by Formula 1-3, the polymer containing the unit represented by Formula 2-3, and PC ₇₀ BM were changed to 0: 1: 1.5 An organic solar cell was prepared.

The spectral conversion characteristics of the organic solar cells prepared in Experimental Examples 1 to 5 and Comparative Examples 1 and 2 were measured under the conditions of 100 mW / cm ² (AM 1.5), and the results are shown in Table 1 below.

V _OC (V) J _SC (mA / cm ² ) FF (%) PCE (%) J _SC (Calc.)
(mA / cm ² ) Experimental Example 1 0.771 18.1 0.661 9.21 17.2 Experimental Example 2 0.786 17.6 0.546 7.64 17.1 Experimental Example 3 0.804 15.7 0.439 5.54 15.8 Experimental Example 4 0.811 9.37 0.412 3.13 13.6 Experimental Example 5 0.859 5.38 0.416 1.91 5.29 Comparative Example 1 0.747 16.8 0.658 8.28 15.9 Comparative Example 2 0.921 6.53 0.469 2.74 6.14

The V _oc is the open voltage, J _sc is the short circuit current, FF is the filling factor (Fill factor), PCE and (η) is means for calculating the value of the short-circuit current energy conversion efficiency, J _sc (Calc.). The open-circuit voltage and the short-circuit current are the X-axis and Y-axis intercepts in the fourth quadrant of the voltage-current density curve, respectively. The higher the two values, the higher the efficiency of the solar cell. The fill factor is the width of the rectangle that can be drawn inside the curve divided by the product of the short-circuit current and the open-circuit voltage. The energy conversion efficiency can be obtained by dividing these three values by the intensity of the irradiated light, and a higher value is preferable. As a result of Table 1, it can be seen that the photoactive layer of the ternary system according to an embodiment of the present invention exhibits higher efficiency than the photoactive layer of the binary system.

2 is a graph showing an energy level of an organic solar cell according to an embodiment of the present invention.

FIG. 3 is a graph showing the UV-vis absorption spectrum of the polymer containing the unit represented by the formula 1-3 and the polymer containing the unit represented by the formula 2-3, and the UV absorption spectrum of FIG. (UV-Vis absorption spectrometer) as an absorption spectrum of a sample of the present invention.

4 shows a polymer (X) containing a unit represented by the above formula (1-3): a polymer (Y) comprising a unit represented by the above formula (2-3): PC ₇₀ BM Of the UV-vis absorption spectrum. Specifically, the UV absorption spectrum of FIG. 4 was an absorption spectrum of a sample in a film state, and was analyzed using a UV-Vis absorption spectrometer.

101: substrate
102: first electrode
103: Hole transport layer
104: photoactive layer
105: second electrode

Claims (11)

A first electrode;
A second electrode facing the first electrode; And
And a photoactive layer disposed between the first electrode and the second electrode,
Wherein the photoactive layer comprises a polymer having a unit represented by the following formula (1);
A polymer comprising a unit represented by the following formula (2); And
Comprising an electron acceptor material,
Wherein the unit represented by the formula (1) and the unit represented by the formula (2) are different from each other.
[Chemical Formula 1]

(2)

In the above formulas (1) and (2)
X1 to X3 and X11 to X13 are the same or different from each other and each independently CRR ', NR, O, SiRR', PR, S, GeRR '
Y1, Y2, Y11 and Y12 are the same or different and are each independently CR ", N, SiR", P or GeR "
A substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted alkoxy group, An unsubstituted aryl group or a substituted or unsubstituted heterocyclic group,
n1, n2, n11 and n12 are each an integer of 1 or more,
When n1, n2, n11 and n12 are each 2 or more, the structures in the parentheses of 2 or more are the same or different,
m1 and m11 are the number of repeating units and are an integer of 1 to 10,000, respectively. The organic solar battery according to claim 1, wherein the unit represented by the formula (1) is represented by the following formula (1-1):
[Formula 1-1]

In Formula 1-1,
The definitions of R1 to R10, n1, n2 and m1 are the same as those in the above formula (1). The organic solar battery according to claim 1, wherein the unit represented by the formula (1)
[Formula 1-3]

In Formula 1-3,
The definition of m1 is the same as in the above formula (1). The organic solar battery according to claim 1, wherein the unit represented by the formula (2) is represented by the following formula (2-1):
[Formula 2-1]

In Formula 2-1,
The definitions of R11 to R20, n11, n12 and m11 are the same as those of the above formula (2). 2. The organic solar battery according to claim 1, wherein the unit represented by the general formula (2)
[Formula 2-3]

In Formula 2-3,
The definition of m11 is the same as in the above formula (2). The organic solar battery according to claim 1, wherein the number average molecular weight of the polymer containing the unit represented by the formula (1) is 5,000 g / mol to 1,000,000 g / mol. The organic solar battery according to claim 1, wherein the number average molecular weight of the polymer containing the unit represented by the formula (2) is 5,000 g / mol to 1,000,000 g / mol. The organic solar battery according to claim 1, wherein the electron acceptor material is one or two or more compounds selected from the group consisting of fullerene, fullerene derivative, vasocopherin, semiconductor element, and semiconducting compound. The polymer according to claim 1, wherein the polymer comprises a unit represented by the formula (1): the polymer having a unit represented by the formula (2): the electron acceptor material is contained in a mass ratio of 0.01 to 0.99: An organic solar cell that is one. The organic solar battery according to claim 1, wherein the polymer comprising the unit represented by the formula (1), the polymer including the unit represented by the formula (2), and the electron acceptor material constitute bulk heterojunction (BHJ). [Claim 2] The method according to claim 1, wherein the photoactive layer is a bilayer structure including an n-type organic compound layer and a p-type organic compound layer,
Wherein the p-type organic compound layer comprises a polymer having a unit represented by the formula (1) and a polymer represented by the formula (2)
Wherein the n-type organic layer comprises the electron acceptor material.

Images