KR102410122B1 - Heterocyclic compound and organic solar cell comprising the same - Google Patents

Abstract

The present specification relates to a heterocyclic compound including the unit of Formula 1 and an organic solar cell including the heterocyclic compound in a photoactive layer.

Description

Heterocyclic compound and organic solar cell comprising the same {HETEROCYCLIC COMPOUND AND ORGANIC SOLAR CELL COMPRISING THE SAME}

The present specification relates to a heterocyclic compound and an organic solar cell including the same.

An organic solar cell is a device capable of directly converting solar energy into electrical energy by applying a photovoltaic effect. Solar cells can be divided into inorganic solar cells and organic solar cells according to the materials constituting the thin film. Conventional inorganic solar cells have already shown limitations in economic feasibility and material supply and demand, so they are easy to process, inexpensive, and have various functionalities. Organic solar cells are attracting attention as a long-term alternative energy source.

It is important to increase the efficiency of a solar cell so that it can output as much electrical energy as possible from solar energy. In order to increase the efficiency, it is important to generate as many excitons as possible inside the semiconductor, but it is also important to draw the generated charge to the outside without loss. do. One of the causes of loss of electric charge is that the generated electrons and holes are annihilated by recombination. Various methods have been proposed as a method for transferring the generated electrons or holes to the electrode without loss, but in most cases an additional process is required and thus manufacturing cost may increase.

Two-layer organic photovoltaic cell (C.W.Tang, Appl. Phys. Lett., 48, 183. (1986)) Efficiencies via Network of Internal Donor-Acceptor Heterojunctions (G. Yu, J. Gao, J. C. Hummelen, F. Wudl, A. J. Heeger, Science, 270, 1789. (1995))

An object of the present specification is to provide a heterocyclic compound and an organic solar cell including the same.

An exemplary embodiment of the present specification provides a heterocyclic compound including a unit of Formula 1 below.

[Formula 1]

In Formula 1,

R ₁ to R ₆ are the same as or different from each other and are each hydrogen; a substituted or unsubstituted alkyl group; a substituted or unsubstituted alkoxy group; or a halogen group,

X ₁ to X ₄ are the same as or different from each other and are each S or O,

Y is O, S or CRR';

R and R' are the same as or different from each other and are each hydrogen; Or a substituted or unsubstituted alkyl group,

n is an integer from 1 to 10,000,

[Push] is represented by the following formula 2 or 3,

[Formula 2]

[Formula 3]

In Formulas 2 and 3,

R ₇ to R ₂₂ are the same as or different from each other and are each hydrogen; a substituted or unsubstituted alkyl group; a substituted or unsubstituted alkoxy group; a substituted or unsubstituted silyl group; -SR" or a halogen group,

R" is a substituted or unsubstituted alkyl group,

X ₅ to X ₁₀ are the same as or different from each other and are each S or O,

는 상기 화학식 1의 주쇄에 연결되는 부위이다.

is a site connected to the main chain of Formula 1 above.

In addition, an exemplary embodiment of the present specification is

a first electrode;

a second electrode provided to face the first electrode; and

It is provided between the first electrode and the second electrode and includes at least one organic material layer including a photoactive layer,

The photoactive layer includes an electron donor and an electron acceptor,

The electron donor provides an organic solar cell including the heterocyclic compound.

Since the heterocyclic compound according to an exemplary embodiment of the present specification has a wide light absorption region and a high LUMO energy level, when the heterocyclic compound is used in the photoactive layer, an organic solar cell having a high level of photoelectric conversion efficiency can be manufactured.

In addition, the organic solar cell according to an exemplary embodiment of the present specification has excellent thermal stability and color characteristics by using the heterocyclic compound as an electron donor.

1 is a view showing an organic solar cell according to an embodiment of the present specification.
2 is a diagram showing the NMR spectrum of Compound A synthesized in Preparation Example of the present application.
3 is a view showing the UV-Vis absorption spectrum of a film sample prepared by dissolving polymers 1 and 2 synthesized in Preparation Example of the present application in chlorobenzene.

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

In the present specification, the 'unit' refers to a structure in which a compound is included in the form of two or more groups in a polymer by a polymerization reaction.

In the present specification, when a part 'includes' a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

In the present specification, when a member is said to be positioned 'on' another member, this includes not only a case in which a member is in contact with another member but also a case in which another member exists between the two members.

In the present specification, the energy level means the size of energy. Therefore, even when the energy level is displayed in the negative (-) direction from the vacuum level, the energy level is interpreted as meaning the absolute value of the corresponding energy value. For example, the HOMO energy level means the distance from the vacuum level to the highest occupied molecular orbital. In addition, the LUMO energy level means the distance from the vacuum level to the lowest unoccupied molecular orbital.

In the present specification, the term 'substitution' means that a hydrogen atom bonded to a carbon atom of a compound is changed to another substituent, and the position to be substituted is not limited as long as the position at which the hydrogen atom is substituted, that is, the position where the substituent is substitutable, is not limited, 2 When substituted or more, two or more substituents may be the same as or different from each other.

As used herein, the term 'substituted or unsubstituted' refers to deuterium; halogen group; hydroxyl group; an alkyl group; cycloalkyl group; alkoxy group; aryloxy group; alkenyl group; aryl group; And it means that it is substituted with one or more substituents selected from the group consisting of a heterocyclic group, is substituted with a substituent to which two or more of the above-exemplified substituents are connected, or does not have any substituents.

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-butyl, 1-methylbutyl, 1-ethylbutyl, pentyl, n-pentyl, iso Pentyl, neopentyl, tert-pentyl, hexyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, heptyl, n-heptyl , 1-methylhexyl, cyclopentylmethyl, cyclohexylmethyl, octyl, n-octyl, tert-octyl, n-methyloctyl, 2,2-dimethyloctyl, 2,3-dimethyloctyl, 2,4-dimethyloctyl, 2,5-dimethyloctyl, 2,6-dimethyloctyl, 2,7-dimethyloctyl, 3,3-dimethyloctyl, 3,4-dimethyloctyl, 3,5-dimethyloctyl, 3,6-dimethyloctyl, 3 ,7-dimethyloctyl, 4,4-dimethyloctyl, 4,5-dimethyloctyl, 1-methylheptyl, 2-methylheptyl, 3-methylheptyl, 4-methylheptyl, 5-methylheptyl, 6-methylheptyl, 2-ethylheptyl, 3-ethylheptyl, 4-ethylheptyl, 5-ethylheptyl, 6-ethylheptyl, 2-ethylhexyl, 3-ethylhexyl, 4-ethylhexyl, 5-ethylhexyl, 2-propylpentyl, n-Nonyl, 2,2-dimethylheptyl, 1-ethyl-propyl, 1,1-dimethyl-propyl, isohexyl, 2-methylhexyl, 3-methylhexyl, 4-methylhexyl, 5-methylhexyl, 2- hexyldecyl, and the like, but is not limited thereto.

In the present specification, the alkoxy group may be a straight chain, branched chain or cyclic chain. Although carbon number of an alkoxy group is not specifically limited, It is preferable that it is C1-C20. Specifically, methoxy, ethoxy, n-propoxy, isopropoxy, i-propyloxy, n-butoxy, isobutoxy, tert-butoxy, sec-butoxy, n-pentyloxy, neopentyloxy, Isopentyloxy, n-hexyloxy, (3,3-dimethylbutyl)oxy, (2-ethylbutyl)oxy, (2-hexyldecyl)oxy, n-octyloxy, n-nonyloxy, n-decylox cy, benzyloxy, and (p-methylbenzyl)oxy, but are not limited thereto.

In the present specification, when the aryl group is a monocyclic aryl group, the number of carbon atoms is not particularly limited, but preferably 6 to 25 carbon atoms. Specifically, the monocyclic aryl group includes, but is not limited to, a phenyl group, a biphenyl group, and a terphenyl group.

In the present specification, when the aryl group is a polycyclic aryl group, the number of carbon atoms is not particularly limited. It is preferable that it has 10-C24. Specifically, the polycyclic aryl group includes, but is not limited to, a naphthyl group, an anthracenyl group, a phenanthryl group, a pyrenyl group, a perylenyl group, a chrysenyl group, and a fluorenyl group. The fluorenyl group may be substituted, and adjacent substituents may combine with each other to form a ring.

In the present specification, the heterocyclic group includes one or more atoms other than carbon and one or more heteroatoms, and specifically, the heterocyclic group may include one or more atoms selected from the group consisting of O, N, Se and S, and the like. Although the number of carbon atoms of the heterocyclic group is not particularly limited, it is preferably from 2 to 60 carbon atoms. Examples of the heterocyclic group include a thiophene group, a furan group, a pyrrole 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 triazine group, a triazole group, Acridyl group, pyridazine group, pyrazinyl group, quinolinyl group, quinazoline group, quinoxalinyl group, isoquinoline group, indole group, carbazole group, benzoxazole group, benzimidazole group, benzothiazole group, benzocarbazole group , benzothiophene group, dibenzothiophene group, benzofuranyl group, phenanthroline group, thiazolyl group, isoxazolyl group, oxadiazolyl group, thiadiazolyl group, phenothiazinyl group and dibenzo There is a furanyl group, and the like, but is not limited thereto.

In the present specification, the silyl group is a substituent including Si and the Si atom is directly connected as a radical, and is represented by -SiR ₁₀₄ R ₁₀₅ R ₁₀₆ , R ₁₀₄ to R ₁₀₆ are the same as or different from each other, and each independently hydrogen; heavy hydrogen; halogen group; an alkyl group; alkenyl group; alkoxy group; cycloalkyl group; aryl group; And it may be a substituent consisting of at least one of a heterocyclic group. Specific examples of the silyl group include a trimethylsilyl group, a triethylsilyl group, a tributylsilyl group, a t-butyldimethylsilyl group, a vinyldimethylsilyl group, a propyldimethylsilyl group, a triphenylsilyl group, a diphenylsilyl group, and a phenylsilyl group. and the like, but is not limited thereto.

는 상기 다른 단위 또는 치환기에 연결되는 부위를 의미한다.In this specification,

means a site connected to the other unit or substituent.

In the present specification, the number of carbon atoms of the substituent having a branched chain includes the number of carbon atoms of the branched chain. For example, in 'Alkyl group having 3 to 20 carbon atoms having at least one methyl group as a branched chain', '3 to 20' is a number including the number of carbon atoms in the 'at least one methyl group'.

An exemplary embodiment of the present specification provides a heterocyclic compound including the unit of Formula 1 above.

Conventionally, a polymer including one electron donating unit (push) and one electron withdrawing unit (pull) was used as the electron donating material (p-type organic material layer) of the organic solar cell.

On the other hand, the unit of Chemical Formula 1 includes one unit as an electron accepting unit (pull), that is, a benzothiadiazole derivative, but two units as an electron donor unit (push), namely, DT. It contains a derivative of enophyran (dithienopyran) and the [Push].

Therefore, the optical and electrochemical advantages of the two electron donor units can be exhibited in a complex manner, and there is an advantage that more light in a wider area can be absorbed.

Specifically, when the heterocyclic compound including the unit of Formula 1 is used as an electron donor material for an organic solar cell, light may be absorbed in a wide wavelength range of 300 nm to 900 nm.

In addition, since it is possible to maintain a low HOMO energy level, the disadvantage of a low open circuit voltage due to a high HOMO energy level, which is a disadvantage of the conventional electron donor material having a wide absorption area, can be compensated for. The conversion efficiency can be increased.

In an exemplary embodiment of the present specification, R ₁ to R ₆ are each a substituted or unsubstituted C 1 to C 20 alkyl group; or a halogen group.

In an exemplary embodiment of the present specification, each of R ₁ to R ₄ is a halogen group.

In an exemplary embodiment of the present specification, R ₁ to R ₄ are each fluorine.

In an exemplary embodiment of the present specification, R ₅ and R ₆ are each a branched-chain alkyl group having 3 to 20 carbon atoms.

In an exemplary embodiment of the present specification, R ₅ and R ₆ are each a branched-chain alkyl group having 5 to 15 carbon atoms.

In an exemplary embodiment of the present specification, R ₅ and R ₆ are each a branched-chain alkyl group having 8 to 12 carbon atoms.

In an exemplary embodiment of the present specification, R ₅ and R ₆ are each an alkyl group having 3 to 20 carbon atoms having at least one alkyl group having 1 to 5 carbon atoms as a branched chain.

In an exemplary embodiment of the present specification, R ₅ and R ₆ are each an alkyl group having 5 to 15 carbon atoms having at least one alkyl group having 1 to 3 carbon atoms as a branched chain.

In an exemplary embodiment of the present specification, R ₅ and R ₆ are each an alkyl group having 8 to 12 carbon atoms having at least one alkyl group having 1 or 2 carbon atoms as a branched chain.

In an exemplary embodiment of the present specification, R ₅ and R ₆ are each an alkyl group having 3 to 20 carbon atoms having at least one methyl group as a branched chain.

In an exemplary embodiment of the present specification, R ₅ and R ₆ are each an alkyl group having 5 to 15 carbon atoms having at least one methyl group as a branched chain.

In an exemplary embodiment of the present specification, R ₅ and R ₆ are each an alkyl group having 8 to 12 carbon atoms having one or more methyl groups as a branched chain.

In the exemplary embodiment of the present specification, R ₅ and R ₆ are each a dimethyloctyl group.

In an exemplary embodiment of the present specification, R ₅ and R ₆ are each a 2,6-dimethyloctyl (2,6-dimetyloctyl) group.

In the exemplary embodiment of the present specification, each of X ₁ to X ₄ is S.

In an exemplary embodiment of the present specification, Y is O.

In the exemplary embodiment of the present specification, the [Push] has a property of donating electrons. Specifically, the [Push] contains thiophene, and thus has excellent electron donating properties.

In an exemplary embodiment of the present specification, R ₇ and R ₈ are each a substituted or unsubstituted alkyl group; a substituted or unsubstituted silyl group; or -SR".

In an exemplary embodiment of the present specification, R ₇ and R ₈ are each a substituted or unsubstituted C 1 to C 20 alkyl group; a silyl group substituted with an alkyl group having 1 to 10 carbon atoms; or -SR", wherein R" is a branched-chain alkyl group having 3 to 20 carbon atoms.

In an exemplary embodiment of the present specification, R ₇ and R ₈ are each a branched-chain alkyl group having 5 to 15 carbon atoms.

In an exemplary embodiment of the present specification, R ₅ and R ₆ are each a branched-chain alkyl group having 5 to 15 carbon atoms.

In an exemplary embodiment of the present specification, R ₅ and R ₆ are each a branched-chain alkyl group having 6 to 10 carbon atoms.

In an exemplary embodiment of the present specification, R ₇ and R ₈ are each an alkyl group having 3 to 20 carbon atoms having at least one alkyl group having 1 to 5 carbon atoms as a branched chain.

In an exemplary embodiment of the present specification, R ₇ and R ₈ are each an alkyl group having 5 to 15 carbon atoms having at least one alkyl group having 2 or 3 carbon atoms as a branched chain.

In an exemplary embodiment of the present specification, R ₇ and R ₈ are each an alkyl group having 6 to 10 carbon atoms having at least one alkyl group having 2 or 3 carbon atoms as a branched chain.

In an exemplary embodiment of the present specification, R ₇ and R ₈ are each an alkyl group having 3 to 20 carbon atoms having at least one ethyl group as a branched chain.

In an exemplary embodiment of the present specification, R ₇ and R ₈ are each an alkyl group having 5 to 15 carbon atoms having at least one ethyl group as a branched chain.

In an exemplary embodiment of the present specification, R ₇ and R ₈ are each an alkyl group having 6 to 10 carbon atoms having at least one ethyl group as a branched chain.

In an exemplary embodiment of the present specification, R ₇ and R ₈ are each an ethylhexyl group.

In an exemplary embodiment of the present specification, R ₇ and R ₈ are each a 2-ethylhexyl group.

In an exemplary embodiment of the present specification, R ₇ and R ₈ are each -SR", and R" is an alkyl group having 3 to 20 carbon atoms having at least one alkyl group having 1 to 5 carbon atoms as a branched chain.

In one embodiment of the present specification, the -SR" is a sulfide group.

In an exemplary embodiment of the present specification, R" is an alkyl group having 5 to 15 carbon atoms having at least one alkyl group having 2 or 3 carbon atoms as a branched chain.

In an exemplary embodiment of the present specification, R" is an alkyl group having 6 to 10 carbon atoms having at least one alkyl group having 2 or 3 carbon atoms as a branched chain.

In an exemplary embodiment of the present specification, R" is an alkyl group having 3 to 20 carbon atoms having one or more ethyl groups as a branched chain.

In an exemplary embodiment of the present specification, R″ is an alkyl group having 5 to 15 carbon atoms having one or more ethyl groups as a branched chain.

In an exemplary embodiment of the present specification, R" is an alkyl group having 6 to 10 carbon atoms having one or more ethyl groups as a branched chain.

In an exemplary embodiment of the present specification, R" is an ethylhexyl group.

In an exemplary embodiment of the present specification, R" is a 2-ethylhexyl group.

In an exemplary embodiment of the present specification, R ₇ and R ₈ are each a silyl group substituted with an alkyl group having 1 to 10 carbon atoms.

In an exemplary embodiment of the present specification, R ₇ and R ₈ are each a silyl group substituted with an alkyl group having 2 to 8 carbon atoms.

In an exemplary embodiment of the present specification, R ₇ and R ₈ are each a silyl group substituted with an alkyl group having 3 to 6 carbon atoms.

In an exemplary embodiment of the present specification, R ₇ and R ₈ are each a silyl group substituted with an alkyl group having 4 or 5 carbon atoms.

In an exemplary embodiment of the present specification, R ₇ and R ₈ are each a silyl group substituted with a butyl group.

In an exemplary embodiment of the present specification, R ₇ and R ₈ are each a tributylsilyl group.

In the exemplary embodiment of the present specification, each of R ₇ and R ₈ is any one selected from the following structural formulas.

In the above structural formula, Bu is a butyl group,

는 상기 화학식 2의 구조에 연결되는 부위이다.

is a site connected to the structure of Formula 2 above.

In an exemplary embodiment of the present specification, R ₉ and R ₁₀ are each hydrogen or a halogen group.

In an exemplary embodiment of the present specification, R ₉ and R ₁₀ are each hydrogen.

In an exemplary embodiment of the present specification, R ₉ and R ₁₀ are each fluorine.

In an exemplary embodiment of the present specification, R ₁₁ to R ₂₀ are each hydrogen.

In an exemplary embodiment of the present specification, R ₂₁ and R ₂₂ are each a substituted or unsubstituted alkoxy group.

In an exemplary embodiment of the present specification, R ₂₁ and R ₂₂ are each an alkoxy group substituted with an alkyl group having 1 to 20 carbon atoms.

In an exemplary embodiment of the present specification, R ₂₁ and R ₂₂ are each a (2-hexyldecyl)oxy ((2-hexyldecyl)oxy) group.

In the exemplary embodiment of the present specification, each of X ₅ to X ₁₀ is S.

In the exemplary embodiment of the present specification, Chemical Formula 1 is represented by the following Chemical Formula 1-1 or 1-2.

[Formula 1-1]

[Formula 1-2]

In Formulas 1-1 and 1-2,

R ₁ to R ₂₂ are the same as defined in Formulas 1 to 3 above.

In an exemplary embodiment of the present specification, Chemical Formula 1 is represented by any one of the following compounds.

In the compound,

n is the same as defined in Formula 1 above.

In an exemplary embodiment of the present specification, the terminal group of the heterocyclic compound is a substituted or unsubstituted heterocyclic group; Or a substituted or unsubstituted aryl group.

In an exemplary embodiment of the present specification, the terminal group of the heterocyclic compound is a 4-(trifluoromethyl)phenyl (4-(trifluoromethyl)phenyl) group.

In an exemplary embodiment of the present specification, the terminal group of the heterocyclic compound is a bromo-thiophene group.

In the exemplary embodiment of the present specification, the terminal group of the heterocyclic compound is a trifluoro-benzene group.

In an exemplary embodiment of the present specification, the number average molecular weight of the heterocyclic compound is 10,000 g/mol to 100,000 g/mol, preferably 30,000 g/mol to 50,000 g/mol.

According to an exemplary embodiment of the present specification, the heterocyclic compound may have a molecular weight distribution of 1 to 10. Preferably, it may have a molecular weight distribution of 1 to 5, more preferably 1 to 2.

An exemplary embodiment of the present specification includes a first electrode; a second electrode provided to face the first electrode; and one or more organic material layers provided between the first electrode and the second electrode and including a photoactive layer, wherein the photoactive layer comprises an electron donor and an electron acceptor, wherein the electron donor comprises the heterocyclic compound An organic solar cell is provided.

In an exemplary embodiment of the present specification, the electron donor is a heterocyclic compound including the unit of Formula 1 above.

In an exemplary embodiment of the present specification, the description of the heterocyclic compound is the same as that described above.

In the exemplary embodiment of the present specification, the electron acceptor may be selected from the group consisting of a fullerene-based compound, vasocuproin, a semiconducting element, a semiconducting compound, and combinations thereof.

In one embodiment of the present specification, the electron acceptor may be a fullerene-based compound, specifically PC ₆₁ BM ([6,6]-phenyl-C ₆₁ -butyric acid methyl ester), PC ₇₁ BM ([6, 6]-phenyl-C ₇₁ -butyric acid methyl ester), mono-oQDMC ₆₀ (mono-o-quino-dimethane C ₆₀ ), bis-oQDMC ₆₀ (bis-o-quino-dimethane C ₆₀ ), ICBA (indene-C ₆₀ -bis-adduct) and bis-PCBM (bis-[6,6]-phenyl-C ₆₁ -butyric acid methyl ester) can

In an exemplary embodiment of the present specification, the mass ratio of the electron donor and the electron acceptor is 1:4 to 4:1, preferably 1:2 to 2:1, more preferably 1:2 to 1:1 day can

In one embodiment of the present specification, the electron donor and electron acceptor may constitute a bulk heterojunction (BHJ).

The bulk heterojunction refers to a mixture of an electron donor material and an electron acceptor material in the photoactive layer.

In the exemplary embodiment of the present specification, the electron donor may be a p-type organic material layer, and the electron acceptor may be an n-type organic material layer.

In one embodiment of the present specification, the photoactive layer may further include an additive.

In an exemplary embodiment of the present specification, the molecular weight of the additive is 50 g/mol to 300 g/mol.

In an exemplary embodiment of the present specification, the additive is an organic material having a boiling point of 30°C to 300°C.

As used herein, an organic material refers to a material including at least one carbon atom.

In one embodiment, the additive is 1,8-diiodooctane (DIO: 1,8-diiodooctane), 1-chloronaphthalene (1-CN: 1-chloronaphthalene), diphenyl ether (DPE: diphenylether) , octane dithiol (octane dithiol) and tetrabromothiophene (tetrabromothiophene) may further include one or two kinds of additives selected from the group consisting of additives.

The organic material layer may further include one or two or more layers selected from the group consisting of a hole injection layer, a hole transport layer, a hole blocking layer, an electron blocking layer, an electron injection layer, an electron transport layer, and a charge generation layer.

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

In one embodiment of the present specification, the substrate may be a glass substrate or a transparent plastic substrate excellent in transparency, surface smoothness, handling and waterproofing properties, but is not limited thereto, and is limited as long as it is a substrate commonly used in organic solar cells doesn't happen Specifically, glass, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polypropylene (PP), polyimide (PI), or triacetyl cellulose (TAC) may be used. The present invention is not limited thereto.

In the exemplary embodiment of the present specification, when the organic solar cell receives a photon from an external light source, electrons and holes are generated between an electron donor and an electron acceptor. The generated holes are transported to the anode through the electron donor layer.

In the exemplary embodiment of the present specification, the organic solar cell may further include an additional organic material layer. The organic solar cell may reduce the number of organic material layers by using an organic material having multiple functions at the same time.

In the exemplary embodiment of the present specification, the first electrode is an anode, and the second electrode is a cathode. In another exemplary embodiment, the first electrode is a cathode, and the second electrode is an anode.

In the exemplary embodiment of the present specification, 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, but is not limited thereto.

In another embodiment, the organic solar cell may be arranged in the order of the anode, the hole transport layer, the photoactive layer, the electron transport layer and the cathode, the cathode, the electron transport layer, the photoactive layer, the hole transport layer and the anode may be arranged in the order , but is not limited thereto.

1 shows an organic solar cell according to an embodiment of the present specification including a first electrode 101, an electron transport layer 102, a photoactive layer 103, a hole transport layer 104, and a second electrode 105 It is also

In the exemplary embodiment of the present specification, the organic solar cell may have a normal structure formed in the order of a substrate, a first electrode, a hole transport layer, a photoactive layer, an electron transport layer, and a second electrode.

In the exemplary embodiment of the present specification, the organic solar cell may have an inverted structure formed in the order of a substrate, a first electrode, an electron transport layer, a photoactive layer, a hole transport layer, and a second electrode.

In an exemplary embodiment of the present specification, the organic solar cell has a tandem structure. In this case, the organic solar cell may include two or more photoactive layers. The organic solar cell according to the exemplary embodiment of the present specification may have one or more photoactive layers.

In another embodiment, the buffer layer may be provided between the photoactive layer and the hole transport layer or between the photoactive layer and the electron transport layer. In this case, the hole injection layer may be further provided between the anode and the hole transport layer. In addition, an electron injection layer may be further provided between the cathode and the electron transport layer.

The material of the first electrode may be a transparent and highly conductive material, but is not limited thereto. For example, metals such as vanadium, chromium, copper, zinc, gold, or alloys thereof; metal oxides such as zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO); combinations of metals and oxides such as ZnO:Al or SnO ₂ :Sb; and conductive polymers such as poly(3-methylthiophene), poly[3,4-(ethylene-1,2-dioxy)thiophene](PEDOT), polypyrrole and polyaniline, but is not limited thereto .

The method of forming the first electrode is not particularly limited, but, for example, sputtering, E-beam, thermal evaporation, spin coating, screen printing, inkjet printing, doctor blade or gravure printing may be used.

When the first electrode is formed on the substrate, it may be subjected to cleaning, moisture removal, and hydrophilic modification.

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

Through the surface modification as described above, the bonding surface potential can be maintained at a level suitable for the surface potential of the photoactive layer. In addition, the formation of the polymer thin film on the first electrode may be facilitated during the modification, and the quality of the thin film may be improved.

As a pretreatment technique for the first electrode, a) a surface oxidation method using a parallel plate discharge, b) a method of oxidizing the surface through ozone generated using UV ultraviolet rays in a vacuum state, and c) oxygen generated by plasma There is a method of oxidation using radicals, and the like.

One of the above methods may be selected according to the state of the first electrode or the substrate. However, whichever method is used, it is preferable to prevent oxygen escaping from the surface of the first electrode or the substrate and to suppress the residual moisture and organic matter as much as possible. In this case, the practical effect of the pre-treatment can be maximized.

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

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

The second electrode may be made of 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; Alternatively, it may be a material having a multilayer structure such as LiF/Al, LiO ₂ /Al, LiF/Fe, Al:Li, Al:BaF ₂ , and Al:BaF ₂ :Ba, but is not limited thereto.

The second electrode may be formed by being deposited in a thermal evaporator showing a vacuum degree of 5×10 ^{- 7} torr or less, but is not limited thereto.

The hole transport layer and/or the electron transport layer material serves to 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 is PEDOT: PSS (Poly (3,4-ethylenediocythiophene) doped with poly (styrenesulfonic acid)); molybdenum oxide (MoO _x ); vanadium oxide (V ₂ O ₅ ); nickel oxide (NiO); Or it may be a tungsten oxide (WO _x ), but 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); Or cesium carbonate (Cs ₂ CO ₃ ) It may be, but is not limited thereto.

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

The heterocyclic compound according to an exemplary embodiment of the present specification may be prepared by a manufacturing method described below. In the following preparations, representative examples are described, but if necessary, a substituent may be added or excluded, and the position of the substituent may be changed. In addition, based on techniques known in the art, starting materials, reactants and reaction conditions may be changed.

In addition, in order to describe the present specification in detail, it will be described in detail with reference to Examples. However, the embodiments according to the present specification may be modified in various other forms, and the scope of the present specification is not to be construed as being limited to the embodiments described below. The embodiments of the present specification are provided to more completely explain the present specification to those of ordinary skill in the art.

< production example : Preparation of Polymers 1 and 2>

(1) Preparation of compound A

(5,5-bis(3,7-dimethyloctyl)-5H-dithieno[3,2-b:2',3'-d]pyran-2,7-diyl) in a round flask equipped with a condenser Bis(tributylstannane)((5,5-bis(3,7-dimethyloctyl)-5H-dithieno[3,2-b:2',3'-d]pyran-2,7-diyl)bis (tributylstannane)) 1 g, 4,7-dibromo-5,6-difluorobenzo [c] [1,2,5] thiadiazole (4,7-dibromo-5,6-difluorobenzo [c] [1,2,5]thiadiazole) 0.74 g (2.5eq), Pd ₂ (dba) ₃ (Tris(dibenzylideneacetone)dipalladium(0)) 0.05g (0.05eq), tri(o-tolyl)phosphine (tri( 0.05 g of o-tolyl) phosphine) was dissolved in toluene and refluxed for 12 hours. Then, the organic layer was extracted through chloroform, and then Compound A was obtained in a yield of 51% using column chromatography. 2 is a diagram showing the NMR spectrum of the synthesized compound A.

(2) Preparation of Polymer 1

5 mmol of the compound A and ((2,5-bis((2-hexyldecyl)oxy)-1,4-phenylene)bis(thiophene-5,2-diyl))bis (trimethylstannane)(((2,5-bis((2-hexyldecyl)oxy)-1,4-phenylene)bis(thiophene-5,2-diyl))bis(trimethylstannane)) 5 mmol, Pd ₂ ( dba) ₃ 0.03 mmol and tri-(o-tolyl) phosphine) 0.06 mmol were added, and then 5 mL of anhydrous chlorobenzene was added. The resulting reaction mixture was heated in a microwave reactor to a temperature of 130° C. for 100 minutes. Then, 0.5 mL of bromobenzotrifluoride (Br-Benzotrifluoride) was added to the mixture, and the resulting solution was further stirred for 20 minutes and cooled to room temperature. Then, the solution was poured into 100 mL of methanol, and the precipitated polymer was obtained by filtration. The collected polymer was subjected to soxhlet extraction in the order of methanol, acetone, hexane and chloroform. Then, the chloroform extract was concentrated and then poured into methanol to precipitate a polymer. The precipitated polymer was again obtained by filtration and dried under vacuum overnight to obtain purified polymer 1 (120 mg, yield 28%) having a purple-black luster.

The results of GPC (Gel Permeation Chromatography) analysis of Polymer 1 were as follows.

- Mn (number average molecular weight) = 28,641 g/mol

- PDI (molecular weight distribution) = 1.98

(3) Preparation of Polymer 2

5 mmol of compound A, ((2,5-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4, 5-b′]dithiophene-2,6-diyl)bis(trimethylstannane)(((2,5-(4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[ 1,2-b:4,5-b']dithiophene-2,6-diyl)bis(trimethylstannane)) 5 mmol, Pd ₂ (dba) ₃ 0.03 mmol and tri-(o-tolyl)phosphine (tri-( o-tolyl)phosphine) 0.06mmol was added, and then 5mL of anhydrous chlorobenzene was added.The resulting reaction mixture was heated in a microwave reactor to a temperature of 130°C for 100 minutes.Then bromobenzotrifluoride (Br -Benzotrifluoride) 0.5mL was added to the mixture, and the resulting solution was further stirred for 20 minutes and cooled to room temperature.Then, the solution was poured into 100mL methanol, and the precipitated polymer was collected by filtration. Soxhlet extraction with methanol, acetone, hexane and chloroform in that order.Then the chloroform extract is concentrated and then poured into methanol to precipitate polymer.Precipitated polymer is again obtained by filtration and dried under vacuum overnight, then purple- A purified polymer 2 (150 mg, yield 32%) having a black luster was obtained.

The results of GPC (Gel Permeation Chromatography) analysis of Polymer 2 were as follows.

- Mn (number average molecular weight) = 31,245 g/mol

- PDI (molecular weight distribution) = 1.81

The UV-Vis absorption spectrum of the film sample prepared by dissolving the polymers 1 and 2 in chlorobenzene is shown in FIG. 3, and the analysis results of the polymers 1 and 2 according to FIG. 3 are shown in Table 1 below.

Mn/D
(g/mol) film Optical
E _g ^opt
(eV) HOMO
(eV) LUMO
(eV) λ _max
(nm) λ _edge
(nm) Polymer 1 28,641/1.98 800 1,000 1.24 -5.23 -3.99 Polymer 2 31,245/1.81 750 950 1.30 -5.28 -3.95

In Table 1, Mn denotes a number average molecular weight, and D denotes a molecular weight distribution. In addition, λ _max means the maximum absorption wavelength of the polymer in the film state, λ _edge means the absorption edge in the film state, and Optical E _g ^opt means the HOMO and LUMO energy bandgap of the polymer in the film state .

The HOMO energy level is determined by measuring an oxidation potential through cyclic voltammetry (CV), obtaining an Eonset (potential at which oxidation starts), and then determining the ferrocene reference value of -4.70 and the The difference in Eonset values of polymers was obtained. The LUMO energy level is obtained by adding an optical bandgap to the HOMO energy level.

<Example: Preparation of organic solar cell>

Example 1-1.

A composite solution was prepared by dissolving the polymer 1 and PC ₇₁ BM in 1:1 chlorobenzene (CB). At this time, the concentration of the polymer 1 and PC ₇₁ BM in the complex solution was adjusted to 4 wt%, and an organic solar cell was prepared with an inverted structure of ITO/ZnO NP/photoactive layer/MoO ₃ /Ag as described below.

A glass substrate (11.5Ω/□) coated with ITO in a bar type of 1.5 cm × 1.5 cm was ultrasonically cleaned using distilled water, acetone, and 2-propanol, and the ITO surface was treated with ozone for 10 minutes. One electrode was formed.

ZnO NPs (N-10, Nanograde Ltd, 2.5wt% in 1-butanol, filtered in 0.45㎛ PTFE) were prepared, and the ZnO NP solution was spin-coated on the first electrode at 4,000rpm for 40 seconds (spin-coating) ), and then heat-treated at 80° C. for 10 minutes to remove the remaining solvent to form an electron transport layer.

Then, for coating the photoactive layer, the composite solution of Polymer 1 and PC ₇₁ BM was spin-coated on the electron transport layer at 70° C. at 700 rpm for 25 seconds.

Then, in a thermal evaporation machine, MoO ₃ was thermally deposited on the photoactive layer at a rate of 0.2 Å/s and a thickness of 10 nm under a vacuum of 10 ^{- 7} torr to prepare a hole transport layer.

Thereafter, Ag was deposited to a thickness of 100 nm at a rate of 1 Å/s in a thermal evaporator to form a second electrode, thereby manufacturing an organic solar cell having an inverted structure.

Example 1-2.

An organic solar cell was manufactured in the same manner as in Example 1-1, except that the composite solution of Polymer 1 and PC ₇₁ BM was spin-coated at 1,000 rpm during the photoactive layer coating in Example 1-1.

Examples 1-3.

An organic solar cell was manufactured in the same manner as in Example 1-1, except that the composite solution of Polymer 1 and PC ₇₁ BM was spin-coated at 1,500 rpm during the photoactive layer coating in Example 1-1.

Examples 1-4.

An organic solar cell was manufactured in the same manner as in Example 1-1, except that a composite solution of Polymer 1 and PC ₇₁ BM was spin-coated at 2,000 rpm when the photoactive layer was coated in Example 1-1.

The photoelectric conversion characteristics of the organic solar cells prepared in Examples 1-1 to 1-4 were measured under 100 mW/cm ² (AM 1.5) conditions, and the results are shown in Table 2 below.

spin-speed
(rpm) V _oc
(V) J _sc
(mA/cm ² ) FF η
(%) mean η
(%) Example 1-1 700 0.833 9.898 0.402 3.32 3.33 0.833 9.752 0.410 3.33 Example 1-2 1,000 0.833 9.795 0.361 2.94 3.27 0.831 10.016 0.433 3.60 Examples 1-3 1,500 0.779 10.872 0.447 3.79 3.93 0.834 10.737 0.454 4.06 Examples 1-4 2,000 0.839 10.900 0.468 4.28 4.27 0.839 10.535 0.481 4.25

Example 2-1.

Polymer 2 and PC ₇₁ BM were dissolved in chlorobenzene (CB) at a ratio of 1:2 to prepare a composite solution. At this time, the concentration of the polymer 2 and PC ₇₁ BM in the composite solution was adjusted to 4 wt %, and an organic solar cell was prepared with an inverted structure of ITO/ZnO NP/photoactive layer/MoO ₃ /Ag as described later.

A glass substrate (11.5Ω/□) coated with ITO in a bar type of 1.5 cm × 1.5 cm was ultrasonically cleaned using distilled water, acetone, and 2-propanol, and the ITO surface was treated with ozone for 10 minutes. One electrode was formed.

ZnO NP (N-10, Nanograde Ltd, 2.5wt% in 1-butanol, filtered in 0.45㎛ PTFE) was prepared, and the ZnO NP solution was spin-coated on the first electrode at 4,000rpm for 40 seconds (spin-coating) After heat treatment at 80° C. for 10 minutes, the remaining solvent was removed to form an electron transport layer.

Then, for coating the photoactive layer, the composite solution of Polymer 2 and PC ₇₁ BM was spin-coated on the electron transport layer at 70° C. at 700 rpm for 25 seconds.

Then, in a thermal evaporation machine, MoO ₃ was thermally deposited on the photoactive layer at a rate of 0.2 Å/s and a thickness of 10 nm under a vacuum of 10 ^{- 7} torr to prepare a hole transport layer.

Thereafter, Ag was deposited to a thickness of 100 nm at a rate of 1 Å/s in a thermal evaporator to form a second electrode, thereby manufacturing an organic solar cell having an inverted structure.

Example 2-2.

An organic solar cell was prepared in the same manner as in Example 2-1, except that a composite solution of Polymer 2 and PC ₇₁ BM was spin-coated at 1,000 rpm when the photoactive layer was coated in Example 2-1.

Example 2-3.

An organic solar cell was manufactured in the same manner as in Example 2-1, except that the composite solution of Polymer 2 and PC ₇₁ BM was spin-coated at 1,500 rpm during the photoactive layer coating in Example 2-1.

Example 2-4.

An organic solar cell was prepared in the same manner as in Example 2-1, except that a composite solution of Polymer 2 and PC ₇₁ BM was spin-coated at 2,000 rpm during the photoactive layer coating in Example 2-1.

The photoelectric conversion characteristics of the organic solar cells prepared in Examples 2-1 to 2-4 were measured under 100 mW/cm ² (AM 1.5) conditions, and the results are shown in Table 3 below.

spin-speed
(rpm) V _oc
(V) J _sc
(mA/cm ² ) FF η
(%) mean η
(%) Example 2-1 700 0.814 12.060 0.529 5.19 5.22 0.813 11.895 0.543 5.25 Example 2-2 1,000 0.820 11.985 0.563 5.53 5.57 0.817 11.760 0.583 5.61 Example 2-3 1,500 0.830 11.297 0.523 4.91 5.38 0.822 11.656 0.610 5.85 Example 2-4 2,000 0.827 10.134 0.575 4.81 4.93 0.825 10.312 0.593 5.04

In Tables 2 and 3, the Spin-speed is the rotation speed of the equipment when the photoactive layer is formed by spin-coating the complex solution on the electron transport layer, V _OC is the open circuit voltage, J _SC is the short circuit current, FF is the fill factor, and η is the energy conversion efficiency. 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, and the higher these two values, the higher the efficiency of the solar cell is. Also, the fill factor is a value obtained by dividing the area of a rectangle that can be drawn inside the curve by the product of the short-circuit current and the open-circuit voltage. The energy conversion efficiency (η) can be obtained by dividing the product of the open circuit voltage (V _oc ), the short-circuit current (J _sc ), and the charging factor (FF) by the intensity of the incident light (P _in ), and a higher value is preferable. .

Looking at the results of Tables 2 and 3, the organic solar cells of the experimental examples using polymers 1 and 2 according to an exemplary embodiment of the present specification as electron donors have high open-circuit voltage, excellent device efficiency such as charge rate, and energy conversion efficiency It can be seen that this is excellent.

101: first electrode
102: electron transport layer
103: photoactive layer
104: hole transport layer
105: second electrode

Claims (14)

Heterocyclic compound comprising a unit of formula (1):
[Formula 1]

In Formula 1,
R ₁ to R ₆ are the same as or different from each other and are each hydrogen; a substituted or unsubstituted alkyl group; a substituted or unsubstituted alkoxy group; or a halogen group,
X ₁ to X ₄ are the same as or different from each other and are each S or O,
Y is O, S or CRR';
R and R' are the same as or different from each other and are each hydrogen; Or a substituted or unsubstituted alkyl group,
n is an integer from 1 to 10,000,
[Push] is represented by the following formula 2 or 3,
[Formula 2]

[Formula 3]

In Formulas 2 and 3,
R ₇ to R ₂₂ are the same as or different from each other and are each hydrogen; a substituted or unsubstituted alkyl group; a substituted or unsubstituted alkoxy group; a substituted or unsubstituted silyl group; halogen group; or -SR";
R" is a substituted or unsubstituted alkyl group,
X ₅ to X ₁₀ are the same as or different from each other and are each S or O,

is a site connected to the main chain of Formula 1 above. The method according to claim 1,
Wherein X _One To X ₁₀ Each of S is a heterocyclic compound. The method according to claim 1,
Formula 1 is a heterocyclic compound represented by the following Formula 1-1 or 1-2:
[Formula 1-1]

[Formula 1-2]

In Formulas 1-1 and 1-2,
R ₁ to R ₂₂ are the same as defined in Formulas 1 to 3 above. The method according to claim 1,
wherein R ₅ and R ₆ are each a branched-chain alkyl group having 3 to 20 carbon atoms. 5. The method according to claim 4,
The R ₅ and R ₆ are each a dimethyl octyl (dimethyloctyl) group is a heterocyclic compound. The method according to claim 1,
wherein R ₇ and R ₈ are each a substituted or unsubstituted C 1 to C 20 alkyl group; a silyl group substituted with an alkyl group having 1 to 10 carbon atoms; or -SR", wherein R" is a branched alkyl group having 3 to 20 carbon atoms, respectively. 7. The method of claim 6,
Wherein R ₇ And R ₈ Each of the heterocyclic compound is any one selected from the following structural formula:

In the above structural formula,
Bu is a butyl group,

is a site connected to the structure of Formula 2 above. The method according to claim 1,
wherein R ₂₁ and R ₂₂ are each a substituted or unsubstituted alkoxy group. 9. The method of claim 8,
wherein R ₂₁ and R ₂₂ are each a (2-hexyldecyl)oxy ((2-hexyldecyl)oxy) group. The method according to claim 1,
Wherein R ₁ To R ₄ Each is a halogen group is a heterocyclic compound. 11. The method of claim 10,
Wherein R ₁ To R ₄ Are each fluorine is a heterocyclic compound. The method according to claim 1,
Formula 1 is a heterocyclic compound represented by any one of the following compounds:

In the compound,
n is the same as defined in Formula 1 above. a first electrode;
a second electrode provided to face the first electrode; and
It is provided between the first electrode and the second electrode and includes at least one organic material layer including a photoactive layer,
The photoactive layer includes an electron donor and an electron acceptor,
The electron donor is an organic solar cell comprising the heterocyclic compound according to any one of claims 1 to 12. 14. The method of claim 13,
The organic material layer further comprises one or two or more layers selected from the group consisting of a hole injection layer, a hole transport layer, a hole blocking layer, an electron blocking layer, an electron injection layer, an electron transport layer and a charge generating layer.

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