JP2014185191A - Copolymer, organic solar cell using the same and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: an organic semiconductor material which has high hole mobility, can exhibit excellent electrical properties and is excellent in photovoltaic conversion efficiency properties; and an organic solar cell comprising the same.SOLUTION: Disclosed herein are a specific terpolymer including a 3,6-carbazole group, an organic solar cell comprising the terpolymer in an organic material layer including a photoactive layer, and a method for manufacturing the same.

Description

  The present specification relates to a novel copolymer, an organic solar cell including the same, and a method for producing the same.

  Since 1992, when UCSB Heeger first showed the potential of solar cells using organic polymers, much research has been done to date. This is a heterojunction thin film element in which an organic polymer that absorbs light and a C60 fullerene derivative or C70 fullerene derivative having an extremely high electron affinity are mixed, with a transparent electrode ITO (indium tin oxide) as an anode, and a low A metal electrode such as Al having a work function is used as the cathode material.

  Light is absorbed by a photoactive layer made of an organic polymer to form electron-hole pairs (excitons). This electron-hole pair moves to the interface between the copolymer and the C60 fullerene derivative or C70 fullerene derivative, and after being separated into electrons and holes, the electrons move to the metal electrode and the holes move to the transparent electrode. This is a technology for generating electrons.

  Currently, the efficiency of organic polymer thin film solar cells using organic polymers has reached 7-8% (Nature Photonics, 2009, 3, 649-653).

  However, so far, the efficiency of organic polymer solar cells is still low compared to the maximum efficiency (˜39%) of solar cells using silicon. Development for organic polymer solar cells with higher efficiency is required.

  Recently, Korean Patent Publication No. 10-2010-0111767 discloses a conductive polymer containing 2,7-carbazole in the main chain and an organic solar cell using the same. The conductive polymer containing 2,7-carbazole in the main chain improves light absorption and hole mobility, and improves the efficiency of the solar cell.

  However, despite the use of 2,7-carbazole, there is a problem that the mobility of holes is relatively low compared to the mobility of electrons, and it is not easy to improve the light efficiency.

Korean Patent Publication No. 10-2010-0111767

Macromolecules 2011, 44 (7), 1909-1919 Nature Photonics, 2009, 3, 649-653 B. Nicolas, M. Alexandre, M. Leclerc, Adv. Mater. 19, 2295-2300 Y. Human, A. Solyman, I. Ahmed, W. C. Darren, K. James, L. G. David, J. Mater. Chem. 21, 13649-13656

  An object of the present specification is to provide an organic semiconductor material that has high hole mobility, can exhibit excellent electrical characteristics, and has excellent photoelectric conversion efficiency characteristics, and an organic solar cell including the same.

The present specification provides a copolymer comprising a first unit of Formula 1 below; a second unit of Formula 2 below; and a third unit of Formula 3 below.
In chemical formulas 1 to 3,
o to r are integers of 0 to 3,
s and t are each an integer of 0 to 4,
R _{a to} R _d are the same or different from each other, and each independently represents hydrogen; deuterium; halogen group; nitrile group; nitro group; imide group; amide group; hydroxy group; substituted or unsubstituted alkyl group; Substituted or unsubstituted alkoxy group; substituted or unsubstituted aryloxy group; substituted or unsubstituted alkylthioxy group; substituted or unsubstituted arylthioxy group; substituted or unsubstituted alkylsulfoxy Substituted or unsubstituted arylsulfoxy group; substituted or unsubstituted alkenyl group; substituted or unsubstituted silyl group; substituted or unsubstituted boron group; substituted or unsubstituted alkylamine group; substituted or unsubstituted Aralkylamine group; substituted or unsubstituted arylamine group; substituted or Substituted or unsubstituted aryl groups; substituted or unsubstituted fluorenyl groups; substituted or unsubstituted carbazole groups; and substituted or unsubstituted containing one or more of N, O, S atoms Or two adjacent substituents selected from the group consisting of heterocyclic groups can form a condensed ring;
R _{1 to} R ₇ are the same or different from each other, and are independently hydrogen, deuterium, halogen group, nitrile group, nitro group, imide group, amide group, hydroxy group, substituted or unsubstituted alkyl group, substituted or non-substituted Substituted or unsubstituted alkoxy group; substituted or unsubstituted aryloxy group; substituted or unsubstituted alkylthioxy group; substituted or unsubstituted arylthioxy group; substituted or unsubstituted alkylsulfoxy Substituted or unsubstituted arylsulfoxy group; substituted or unsubstituted alkenyl group; substituted or unsubstituted silyl group; substituted or unsubstituted boron group; substituted or unsubstituted alkylamine group; substituted or unsubstituted Aralkylamine group; substituted or unsubstituted arylamine group; substituted or Substituted or unsubstituted aryl groups; substituted or unsubstituted fluorenyl groups; substituted or unsubstituted carbazole groups; and substituted or unsubstituted containing one or more of N, O, S atoms Or two adjacent substituents selected from the group consisting of heterocyclic groups can form a condensed ring.

  In addition, the present specification includes a first electrode; a second electrode facing the first electrode; and one or more organic layers including the photoactive layer provided between the first electrode and the second electrode. One or more of the organic material layers provide an organic solar battery including a copolymer including the chemical formula 1, the chemical formula 2, and the chemical formula 3.

  The present specification further comprises: preparing a substrate; forming a first electrode in a region of a back surface of the substrate; a copolymer including the above Formula 1, Formula 2, and Formula 3 on the first electrode. And a method of manufacturing an organic solar cell, comprising: forming a second electrode on the organic layer.

  The copolymer of the present specification can be used as a material for an organic material layer of an organic solar cell, and an organic solar cell using the copolymer can exhibit excellent characteristics such as an increase in open-circuit voltage and an increase in efficiency. . In particular, the new copolymer according to the present specification can exhibit excellent characteristics with a deep HOMO level and a high charge mobility. The copolymer according to the present specification can be used purely in an organic solar cell or mixed with impurities, and can be applied by a solution coating method. In addition, the light efficiency can be improved, and the lifetime characteristics of the device can be improved by the thermal stability of the compound.

It is the graph which compared the charge mobility of the copolymer containing a 3, 6- carbazole group and the copolymer containing a 2, 7- carbazole group. It is a graph which shows the current-voltage curve of the organic solar cell of Examples 2 thru | or 4 and Comparative Examples 1 and 2. It is a graph which shows the mobility of the hole of an electric charge mobility measuring element to which the polymer of comparative example 1 is applied, and an electric charge. It is a graph which shows the mobility of the hole of a charge mobility measuring element to which the polymer of Example 2 is applied, and a charge. It is a graph which shows the mobility of the hole of a charge mobility measuring element to which the polymer of Example 3 is applied, and a charge. It is a graph which shows the mobility of the hole of a charge mobility measuring element to which the polymer of Example 4 is applied, and a charge.

  Hereinafter, the present specification will be described in detail.

  In the present specification, the copolymer provides a copolymer including the first unit of Chemical Formula 1, the second unit of Chemical Formula 2, and the third unit of Chemical Formula 3.

  In the present specification, the “unit” means a repeating structure contained in a monomer contained in a copolymer and a structure in which the monomer is bonded into the polymer by polymerization.

  The first unit of Formula 1 includes a 3,6-carbazole group. The organic solar cell including the copolymer including the first unit has higher charge mobility than the copolymer including the 2,7-carbazole group, and has an effect of contributing to the stability of the copolymer.

  FIG. 1 is a graph comparing charge mobility between a copolymer containing 3,6-carbazole groups and a copolymer containing 2,7-carbazole groups.

  In one embodiment of the present specification, the first unit of Formula 1 is preferably greater than 0 mol% and not greater than 45 mol% in the total monomer content.

  In another embodiment, 0.1 mol% to 30 mol% or less, in another example, 0.5 mol% to 20 mol% or less, and in another example, 0.5 mol% or less. % To 15 mol%, and in other examples from 1 mol% to 10 mol%.

  In the copolymer containing a 3,6-carbazole group, the nitrogen atom is included in the conjugation of the main chain, the hole can be stabilized, and the hole and charge mobility are increased. As a result, the hole mobility and the electron mobility of the organic solar cell can be balanced, an excellent electrical characteristic can be exhibited, and an organic semiconductor material having an excellent photoelectric conversion efficiency characteristic and an organic solar including the same Provide batteries.

  In the case of a copolymer containing only an existing 2,7-carbazole group, since a nitrogen atom is not included in the conjugation, excellent electrical characteristics cannot be expected.

  However, in the copolymer containing the chemical formula 1, when the content of the first unit of the chemical formula 1 is 45 mol% or less in the total content of the monomer, due to the characteristics of the carbazole group having a relatively low absorbance, A decrease in light absorption can be minimized, and a copolymer having an appropriate molecular weight can be produced.

  Examples of the substituent will be described below, but the present invention is not limited thereto.

  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 1-20. Specific examples include, but are not limited to, methyl, ethyl, propyl, isopropyl, butyl, t-butyl, pentyl, hexyl and heptyl.

  In the present specification, the alkenyl group may be linear or branched, and the number of carbon atoms is not particularly limited, but is preferably 2 to 40. Specific examples include, but are not limited to, an alkenyl group substituted with an aryl group such as a stilbenyl group and a styrenyl group.

  In the present specification, the alkoxy group may be a straight chain, a branched chain or a ring chain. Although carbon number of an alkoxy group is not specifically limited, It is preferable that it is C1-C25. Specifically, it can be a methoxy group, an ethoxy group, an n-propyloxy group, an iso-propyloxy group, an n-butyloxy group, a cyclopentyloxy group, or the like, but is not limited thereto.

  In the present specification, the cycloalkyl group is not particularly limited, but preferably has 3 to 60 carbon atoms, and particularly preferably a cyclopentyl group or a cyclohexyl group.

  In the present specification, the halogen group may be fluorine, chlorine, bromine or iodine.

  In the present specification, the aryl group may be monocyclic, and the number of carbon atoms is not particularly limited, but is preferably 6 to 60 carbon atoms. Specific examples of the aryl group include monocyclic aromatic groups such as phenyl group, biphenyl group, triphenyl group, terphenyl group, and stilbene group, and naphthyl group, anthracenyl group, phenanthrenyl group, pyrenyl group, perylenyl group, and tetracenyl group. , Polycyclic aromatic groups such as, but not limited to, a chrysenyl group, a fluorenyl group, an acenaphthacenyl group, a triphenylene group, a fluoranthene group, and the like.

  In the present specification, the heterocyclic group is a heterocyclic group containing O, N, or S as a hetero atom, and the number of carbons is not particularly limited, but is preferably 2 to 60 carbons. Examples of heterocyclic groups include thiophene group, furan group, pyrrole group, imidazole group, thiazole group, oxazole group, oxadiazole group, triazole group, pyridyl group, bipyridyl group, triazine group, acridyl group, pyridazine group, quinolinyl. Group, isoquinoline group, indole group, carbazole group, benzoxazole group, benzimidazole group, benzthiazole group, benzcarbazole group, benzothiophene group, dibenzothiophene group, benzfuranyl group, phenanthroline group and dibenzofuranyl group However, it is not limited to these.

In this specification, the carbon number of the imide group is not particularly limited, but is preferably 1 to 25 carbon atoms. Specifically, it can be a compound having the following structure, but is not limited thereto.

In the present specification, the amide group may be substituted 1 or 2 with nitrogen of the amide group with hydrogen, a linear, branched or cyclic alkyl group having 1 to 25 carbon atoms, or an aryl group having 6 to 25 carbon atoms. . Specifically, it can be a compound having the following structural formula, but is not limited thereto.

In the present specification, the ester group may be substituted with a C 1-25 linear, branched or cyclic alkyl group, or a C 6-25 aryl group in which the oxygen of the ester group is oxygen. Specifically, it can be a compound having the following structural formula, but is not limited thereto.

  In the present specification, the heteroaryl group can be selected from the examples of the heterocyclic group described above.

In the present specification, a fluorenyl group is a structure in which two ring organic compounds are linked via one atom, and examples thereof include:
and so on.

In the present specification, the fluorenyl group includes a structure of an open fluorenyl group, wherein the open fluorenyl group is a structure in which two ring compounds are connected via one atom, and one ring compound is connected to each other. A cut-out structure, for example
and so on.

  In this specification, the number of carbon atoms of the amine group is not particularly limited, but is preferably 1-30. Specific examples of the amine group include methylamine group, dimethylamine group, ethylamine group, diethylamine group, phenylamine group, naphthylamine group, biphenylamine group, anthracenylamine group, 9-methyl-anthracenylamine group, diphenylamine group, Examples include, but are not limited to, a phenyl naphthylamine group, a ditolylamine group, a phenyltolylamine group, and a triphenylamine group.

  In this specification, examples of the arylamine group include a substituted or unsubstituted monocyclic diarylamine group, a substituted or unsubstituted polycyclic diarylamine group, or a substituted or unsubstituted monocyclic and polycyclic group. Means a cyclic diarylamine group;

  In the present specification, the aryl group in the aryloxy group, arylthioxy group, arylsulfoxy group and aralkylamine group is as exemplified for the aryl group described above.

  In this specification, the alkyl group in the alkylthioxy group, the alkylsulfoxy group, the alkylamine group, and the aralkylamine group is as exemplified for the alkyl group described above.

  In the present specification, the heteroaryl group in the heteroarylamine group can be selected from the examples of the heterocyclic group described above.

  In the present specification, an arylene group, an alkenylene group, a fluorenylene group, a carbazolylene group, and a heteroarylene group are divalent groups of an aryl group, an alkenyl group, a fluorenyl group, and a carbazole group, respectively. Except for these being each a divalent group, the description of the aryl group, alkenyl group, fluorenyl group, and carbazole group described above is applicable.

  In this specification, the term “substituted or unsubstituted” refers to deuterium, halogen group, alkyl group, alkenyl group, alkoxy group, cycloalkyl group, silyl group, arylalkenyl group, aryl group, aryloxy group. Alkylthioxy group, alkylsulfoxy group, arylsulfoxy group, boron group, alkylamine group, aralkylamine group, arylamine group, heteroaryl group, carbazole group, arylamine group, aryl group, fluorenyl group, nitrile group; A nitro group; substituted with one or more substituents selected from the group consisting of a hydroxy group and a heterocyclic group containing one or more of N, O, S atoms, or any substituents Means no.

In one embodiment of the present specification, the copolymer includes a copolymer represented by the following chemical formula 4.

In Formula 4,
l is the mole fraction, a real number 0 <l ≦ <1,
m is a mole fraction, a real number of 0 ≦ m <1, and l + m = 1.
n is an integer from 1 to 10,000;
A is Formula 1 above,
B, C, and D are the same or different from each other, and each independently have the chemical formula 2 or 3,
At least one of B, C, and D is Formula 3.

  In one embodiment of the present specification, A in Formula 4 is Formula 1 and B is Formula 3.

  In another embodiment, C in Formula 4 is Formula 2.

  In another embodiment, D in Formula 4 is Formula 3.

  In one embodiment of the present specification, B and D of Formula 4 above are the Formula 3, and C provides the copolymer of Formula 2.

In one embodiment of the present specification, the copolymer provides a copolymer including the compound represented by the following Chemical Formula 5.

In the chemical formula 5, R _{a to} R _d and R _{1 to} R ₇ , o, p, q, r, s, and t are as defined in the chemical formulas 1 to 3,
1 is a mole fraction, which is a real number of 0 <l ≦ <1, m is a mole fraction, 0 ≦ m <1, a real number of l + m = 1, and n is 1 It is an integer of 10,000.

In one embodiment of the present specification, R _a and R _b are hydrogen.

In another embodiment, R _c and R _d are hydrogen.

  In another embodiment, s is 1.

  In another embodiment, t is 1.

In another embodiment, R ₄ is hydrogen.

In another embodiment, R ₅ is hydrogen.

In another embodiment, R ₆ is hydrogen.

In another embodiment, R ₇ is hydrogen.

In one embodiment of the present specification, the copolymer includes a fourth unit represented by the following chemical formula 6 and a fifth unit represented by the following chemical formula 7.

In Chemical Formulas 6 and 7,
R ₁ is as defined in Chemical Formula 1,
R ₂ and R ₃ are as defined in Chemical Formula 2,
l is the mole fraction, a real number 0 <l ≦ <1,
m is a mole fraction, and is a real number of 0 ≦ m <1, and l + m = 1.

  In one embodiment of the present specification, the terminal group of the copolymer includes hydrogen, deuterium, halogen group, nitrile group, nitro group, imide group, amide group, hydroxy group, substituted or unsubstituted alkyl group; Substituted or unsubstituted cycloalkyl group; substituted or unsubstituted alkoxy group; substituted or unsubstituted aryloxy group; substituted or unsubstituted alkylthioxy group; substituted or unsubstituted arylthioxy group; substituted or unsubstituted Substituted or unsubstituted arylsulfoxy group; substituted or unsubstituted alkenyl group; substituted or unsubstituted silyl group; substituted or unsubstituted boron group; substituted or unsubstituted alkylamine group; Unsubstituted aralkylamine group; substituted or unsubstituted arylamine group; Is an unsubstituted heteroarylamine group; a substituted or unsubstituted aryl group; a substituted or unsubstituted fluorenyl group; a substituted or unsubstituted carbazole group; and a substituted or unsubstituted group containing one or more of N, O, and S atoms Selected from the group consisting of unsubstituted heterocyclic groups.

  In one embodiment of the present specification, the terminal group of the copolymer is a heterocyclic group.

  In one embodiment of the present specification, the terminal group of the copolymer is an aryl group.

  According to one embodiment of the present specification, the number average molecular weight of the copolymer is preferably 500 to 1,000,000 g / mol. The number average molecular weight of the copolymer is preferably 10,000 to 100,000.

  According to one embodiment of the present specification, the copolymer may have a molecular weight distribution of 1 to 100. Preferably, the copolymer has a molecular weight distribution of 1 to 3.

  The lower the molecular weight distribution and the higher the number average molecular weight, the better the electrical and mechanical properties.

  Moreover, in order to make the application of the solution coating method advantageous with a certain degree of solubility, the number average molecular weight is preferably 100,000 or less.

  The copolymer containing the above chemical formula 1 can be produced based on the production examples described later.

  The copolymer according to the present specification can be produced by a multistage chemical reaction. Monomers are prepared through an alkylation reaction, a Grignard reaction, a Suzuki coupling reaction and a Stille coupling reaction, and then the final polymer is formed through a carbon-carbon coupling reaction such as a Stille coupling reaction. Can be manufactured. When the substituent to be introduced is a boronic acid or boronic ester compound, it can be produced through a Suzuki coupling reaction, and the substituent to be introduced is tributyltin. In the case of a compound, it can be produced through a Still coupling reaction, but is not limited thereto.

  In addition, the present specification provides an organic solar cell using a copolymer including the above Chemical Formula 1, Chemical Formula 2, and Chemical Formula 3.

  The present specification includes a first electrode; a second electrode opposed to the first electrode; and one or more organic layers including a photoactive layer provided between the first electrode and the second electrode, One or more of the organic layers provide an organic solar battery that includes the above-described copolymer.

  The organic solar cell according to one 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.

  The substrate can be a glass substrate or a transparent plastic substrate excellent in transparency, surface smoothness, ease of handling and waterproofness, but is not limited thereto, and is limited as long as it is a substrate usually used for organic solar cells. There is no. Specific examples include glass, PET (polyethylene terephthalate), PEN (polyethylene naphthaleate), PP (polypropylene), PI (polyimide), and TAC (triacetyl cell), but are not limited thereto.

The first electrode may be a transparent material having excellent conductivity, but is not limited thereto. Specifically, it can be indium tin oxide (ITO), tin oxide (SnO ₂ ), and zinc oxide (ZnO), but is not limited thereto.

The second electrode may be a metal having a small work function, but is not limited thereto. Specifically, a metal such as lithium, magnesium, and aluminum, or an alloy thereof, Al: Li, Al: BaF ₂ , Al: BaF ₂ : Ba can be a multi-layered material, but is not limited thereto. It is not something.

  The hole transport layer and / or electron transport layer material may be a material that increases the probability that the generated charges move to the electrode by efficiently transferring electrons and holes to the photoactive layer, but is particularly limited. There is no.

The hole transport layer material is PEDOT: PSS (Poly (3,4-ethylenediothiophene) doped with poly (styrenesulfonic acid)), N, N′-bis (3-methylphenyl) -N, N′-diphenyl- [ 1,1′-biphenyl] -4,4′-diamine (TPD). The electron transport layer material is aluminum trihydroxyquinolyl (Alq ₃ ), a PBD of a 1,3,4-oxadiazole derivative (2- (4-biphenyl) -5-phenyl-1,3,4-oxadiazole). Quinoxaline derivative TPQ (1,3,4-tris [(3-phenyl-6-trifluoromethyl) quinoxaline-2-yl] benzene), triazole derivative, and the like.

  The photoactive layer can include an electron donor material and an electron acceptor material.

  In one embodiment of the present specification, the electron donor material is a copolymer including the first unit of Formula 1, the second unit of Formula 2, and the third unit of Formula 3.

In one embodiment of the present specification, the electron acceptor substance may be fullerene, a fullerene derivative, bathocuproine, a semiconducting element, a semiconducting compound, and a combination thereof, specifically, PC ₆₁ BM (phenyl C ₆₁ − butyric acid methyl ester) or may be a _{PC 71 BM (phenyl C 71 -butyric} acid methyl ester).

  In the photoactive layer, the electron donor material and the electron acceptor material may form a bulk heterojunction (BHJ). The electron donor material and the electron acceptor material can be mixed at a ratio of 1:10 to 10: 1 (w / w), and after mixing, at 30 to 300 ° C. for 1 second to maximize the characteristics. Can be annealed for 24 hours.

  The photoactive layer may have a thickness of 10 to 10,000 mm, but is not limited thereto.

  In one embodiment of the present specification, a buffer layer may be further introduced between the photoactive layer and the first electrode, and an electron transfer layer between the photoactive layer and the second electrode, A hole blocking layer or an optical space layer is further introduced.

  In the present specification, as described in Korean Patent Publication No. 10-2010-0111767, which is introduced as a reference, the organic solar cell includes a substrate, a first electrode, a photoactive layer, and a second electrode. And a copolymer containing the first unit of Formula 1, the second unit of Formula 2, and the third unit of Formula 3 in the photoactive layer is used as an electron donor, and is a C60 fullerene derivative or a C70 fullerene derivative. Is formulated as an electron acceptor.

  In one embodiment of the present specification, the photoelectric conversion material of the photoactive layer includes a copolymer including a first unit of Formula 1, a second unit of Formula 2, a third unit of Formula 3, and an electron acceptor. The mixing ratio is blended at a weight ratio of 1: 0.5 to 1: 4.

  In one embodiment of the present specification, the photoelectric conversion material of the photoactive layer includes a copolymer including a first unit of Formula 1, a second unit of Formula 2, a third unit of Formula 3, and a C60 fullerene derivative or C70. The mixing ratio with the fullerene derivative is blended at a weight ratio of 1: 0.5 to 1: 4.

  At this time, the fullerene derivative is blended in less than 0.5 weight ratio as compared with the copolymer including the first unit of Chemical Formula 1, the second unit of Chemical Formula 2, and the third unit of Chemical Formula 3. When the content of the crystallized fullerene derivative is insufficient, the movement of the generated electrons is obstructed, and when the weight ratio exceeds 4%, the first unit of Formula 1 that absorbs light, the second unit of Formula 2 The amount of the copolymer containing the unit and the third unit of the chemical formula 3 is relatively unfavorably decreased because the light is not efficiently absorbed.

  In one embodiment of the present specification, the organic solar cell may be arranged in the order of the anode electrode, the photoactive layer and the cathode electrode, or may be arranged in the order of the cathode electrode, the photoactive layer and the anode electrode, It is not limited to this.

  In another embodiment, the organic solar cell may be arranged in the order of an anode electrode, a hole transport layer, a photoactive layer, an electron transport layer, and a cathode electrode. The cathode electrode, the electron transport layer, the photoactive layer, The hole transport layer and the anode electrode may be arranged in this order, but are not limited thereto.

  The organic solar cell of this specification can be manufactured with a material and a method well-known in this technical field except that an organic substance layer contains the copolymer of this specification.

  An organic solar cell manufacturing method according to another embodiment of the present specification includes a step of preparing a substrate, a step of forming a first electrode in a region of a back surface of the substrate, and the above-described step on the first electrode. Forming an organic material layer containing the copolymer and forming a second electrode on the organic material layer.

  The organic solar cell of this specification can be manufactured by laminating | stacking a 1st electrode, an organic substance layer, and a 2nd electrode sequentially on a board | substrate, for example. At this time, it can be coated by a wet method such as gravure printing, offset printing, screen printing, ink jet, spin coating, spray coating, etc., but is not limited to these methods.

  In the organic solar cell including the copolymer, the copolymer including the first unit of Chemical Formula 1, the second unit of Chemical Formula 2, and the third unit of Chemical Formula 3 can be used as an electron donor.

  The production method of the first unit of the chemical formula 1, the second unit of the chemical formula 2, the third unit of the chemical formula 3 and the production of the organic solar cell using them will be specifically described in the following examples. However, the following examples are for illustrating the present invention, and the scope of the present invention is not limited thereto.

[Example 1. Monomer synthesis]
{Example A. Production of N-9′-heptadecanyl-3,6-dibromocarbazole (N-9′-Heptadecanyl-3,6-dibromocarbazole)}

  In this example, 9-heptadecane p-toluenesulfonate was prepared with reference to previous literature (B. Nicolas, M. Alexander, M. Leclerc, Adv. Mater. 19, 2295-2300).

  To 30 ml of anhydrous dimethyl sulfoxide, 3,6-dibromo-9H-carbazole (3,6-Dibromo-9H-carbazole, 4.00 g, 12.3 mmol) and potassium hydroxide, 6.90 g 123 mmol), and after stirring for 1 hour, 9-heptadecane p-toluenesulfonate (7.58 g, 18.5 mmol) was added and stirred for 12 hours.

The mixture was cooled to room temperature, extracted with hexane / ethyl acetate (3: 1 v / v), washed with water, and then water remaining in the solution was removed with magnesium sulfate (MgSO ₄ ). did. The solvent was removed under reduced pressure, and the remaining residue was purified by silica gel column chromatography to obtain a white solid.
Yield: 86%
1H NMR: (300 MHz, CDCl3, ppm): δ 8.16 (br, 2H); 7.48 (br, 4H); 4.47 (br, 1H); 2.23 (br, 2H); 1.90 (br, 2H); 1.11 ( br, 24H); 0.83 (t, J = 7.1 Hz, 6H)
13C NMR (75 MHz, CDCl3, ppm): δ 129.39; 128.93; 123.73; 123.40; 113.42; 110.94; 57.23; 34.03; 32.13; 29.68; 29.66; 29.50; 27.02; 22.99; 14.47
mp: 53.6-55.7 ° C
HRMS (EI ⁺ , m / z) [M] ⁺ calculated value C ₂₉ H ₄₁ Br ₂ N561.1606, experimental value 561.1608

{Example B. 3,6-bis (4 ′, 4 ′, 5 ′, 5′-tetramethyl-1 ′, 3 ′, 2′-dioxaborolan-2′-yl) -N-9′-heptadecanylcarbazole (3,3 Production of 6-Bis (4 ′, 4 ′, 5 ′, 5′-tetramethyl-1 ′, 3 ′, 2′-dioxabolan-2′-yl) -N-9′-heptadecanylcarbazole)}

  After dissolving N-9′-heptadecanyl-3,6-dibromocarbazole (N-9′-Heptadecanyl-3,6-dibromocarbazole, 4.00 g, 7.10 mmol) in 30 ml of anhydrous tetrahydrofuran (Anhydrous tetrahydrofuran) The temperature was lowered to −78 ° C., and 1.7 M n-butyllithium (1.7 M n-Butyllithium solution in hexane, 17.5 ml, 29.8 mmol) dissolved in hexane was added. After stirring for 1 hour, 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxabololane) 5.28 g, 28.4 mmol) was added at once, and the temperature was raised to room temperature, followed by stirring for 12 hours.

Water was added to the mixture to complete the reaction, and the mixture was extracted with diethyl ether, washed with water, and then water remaining in the solution was removed with magnesium sulfate (MgSO ₄ ). The solvent was removed under reduced pressure, and the remaining residue was purified by silica gel column chromatography to obtain a white solid.
Yield: 57%
1H NMR (300 MHz, CDCl3, ppm): δ 8.68 (br, 2H); 7.87 (br, 2H); 7.56 (br, 1H); 7.39 (br, 1H); 4.58 (br, 1H); 2.29 (br , 2H); 1.90 (br, 2H); 1.39 (br, 24H); 1.13 (br, 24H); 0.81 (t, J = 6.8 Hz, 6H)
13C NMR (75 MHz, CDCl3, ppm): δ 144.61; 141.20; 132.08; 128.40; 124.25; 122.85; 111.39; 108.66; 83.90; 56.94; 34.10; 32.14; 29.68; 27.10; 25.36; 22.99; 14.47
mp: 147.8-149.2 ° C
HRMS (EI ⁺ , m / z) [M] ⁺ calculated value C ₂₉ H ₄₁ Br ₂ N 567.5100, experimental value 567.5103

[Example 2. Synthesis of Copolymer 1]
3,6-Bis (4 ′, 4 ′, 5 ′, 5′-tetramethyl-1 ′, 3 ′, 2′-dioxaborolan-2′-yl) -N-9′-heptadecanyl in 3 ml of toluene Carbazole (3,6-Bis (4 ′, 4 ′, 5 ′, 5′-tetramethyl-1 ′, 3 ′, 2′-dioxabolan-2′-yl) -N-9′-heptadecanylcarbazole, 4.1 mg, 0.006 mmol) and 2,7-bis (4 ′, 4 ′, 5 ′, 5′-tetramethyl-1 ′, 3 ′, 2′-dioxaborolan-2-yl) -9,9-dioctylfluorene ( 2,7-Bis (4 ′, 4 ′, 5 ′, 5′-tetramethyl-1 ′, 3 ′, 2′-dioxabolan-2′-yl) -9,9-dioctylfluorene, 197 mg, 0.306 mmol) 4,7-bis 5-bromo-2-thienyl) -2,1,3-benzothiadiazole (4,7-bis- (5-bromo-2-thienyl) -2,1,3-benzothiadiazole, 143 mg, 0.312 mmol); A 20% tetraethylammonium hydroxide aqueous solution (aq. 20% tetraethylammonium hydroxide solution, 3 ml), tetrakis (triphenylphosphine) palladium 0 (tetrakis (triphenylphosphine) paladium 0, 5 mg), and Aliquat 336 were stirred under reflux. . After 72 hours, phenylboronic acid (0.05 g) was added and reacted for 3 hours, and then bromobenzene (bromobenzene, 0.12 g) was added and further reacted for 4 hours. The mixture was cooled to room temperature and poured into methanol, and then the solid was filtered. After Soxhlet extraction into acetone, hexane, and chloroform, the solid was precipitated again, and the solid was filtered.
Yield: 61%
Number average molecular weight: 11,400 g / mol
Weight average molecular weight: 42,900 g / mol

[Example 3. Synthesis of Copolymer 2]
3,6-Bis (4 ′, 4 ′, 5 ′, 5′-tetramethyl-1 ′, 3 ′, 2′-dioxaborolan-2′-yl) -N-9′-heptadecanyl in 3 ml of toluene Carbazole (3,6-Bis (4 ′, 4 ′, 5 ′, 5′-tetramethyl-1 ′, 3 ′, 2′-dioxabolan-2′-yl) -N-9′-heptadecanylcarbazole, 21 mg, 0. 03 mmol) and 2,7-bis (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) -9,9-dioctylfluorene (2,7-Bis (4,4 , 5,5-tetramethyl-1,3,2-dioxabolan-2-yl) -9,9-dioctylfluorene, 161 mg, 0.28 mmol) and 4,7-bis- (5-bromo- -Thienyl) -2,1,3-benzothiadiazole (4,7-bis- (5-bromo-2-thienyl) -2,1,3-benzothiadiazole, 143 mg, 0.31 mmol) and 20% tetraethylammonium Aqueous hydroxide aqueous solution (aq. 20% tetraethylammonium hydroxide solution, 3 ml), tetrakis (triphenylphosphine) palladium 0 (tetrakis (triphenylphosphine) palladium 0, 5 mg) and Aliquat 336 were added and stirred under reflux. After 72 hours, phenylboronic acid (0.05 g) was added and reacted for 3 hours, and then bromobenzene (bromobenzene, 0.12 g) was added and further reacted for 4 hours. The mixture was cooled to room temperature and poured into methanol, and then the solid was filtered. After Soxhlet extraction into acetone, hexane, and chloroform, the solid was precipitated again, and the solid was filtered.
Yield: 54%
Number average molecular weight: 14,500 g / mol
Weight average molecular weight: 42,100 g / mol

[Example 4. Synthesis of Copolymer 3]
3,6-Bis (4 ′, 4 ′, 5 ′, 5′-tetramethyl-1 ′, 3 ′, 2′-dioxaborolan-2′-yl) -N-9′-heptadecanyl in 3 ml of toluene Carbazole (3,6-Bis (4 ′, 4 ′, 5 ′, 5′-tetramethyl-1 ′, 3 ′, 2′-dioxabolan-2′-yl) -N-9′-heptadecanylcarbazole, 42 mg, 0. 064 mmol) and 2,7-bis (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) -9,9-dioctylfluorene (2,7-Bis (4,4 , 5,5-tetramethyl-1,3,2-dioxabolan-2-yl) -9,9-dioctylfluorene, 147 mg, 0.256 mmol) and 4,7-bis- (5-bromide). -2-thienyl) -2,1,3-benzothiadiazole (4,7-bis- (5-bromo-2-thienyl) -2,1,3-benzothiadiazole, 143 mg, 0.31 mmol), and 20% An aqueous solution of tetraethylammonium hydroxide (aq. 20% tetraethylammonium hydroxide, 3 ml), tetrakis (triphenylphosphine) palladium 0 (tetrakis (triphenylphosphine) palladium0, 5 mg) and Aliquat 336 were stirred and refluxed. After 72 hours, phenylboronic acid (0.05 g) was added and reacted for 3 hours, and then bromobenzene (bromobenzene, 0.12 g) was added and further reacted for 4 hours. The mixture was cooled to room temperature and poured into methanol, and then the solid was filtered. After Soxhlet extraction into acetone, hexane, and chloroform, the solid was precipitated again, and the solid was filtered.
Yield: 61%
Number average molecular weight: 6,000 g / mol
Weight average molecular weight: 9,200 g / mol

[Comparative Example 1. Synthesis of Copolymer 4]
To 3 ml of toluene, 2,7-bis (4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) -9,9-dioctylfluorene (2,7-Bis (4,4 , 5,5-tetramethyl-1,3,2-dioxabolan-2-yl) -9,9-dioctylfluorene, 200 mg, 0.32 mmol) and 4,7-bis (5-bromo-2-thienyl) -2 , 1,3-benzothiadiazole (4,7-bis- (5-bromo-2-thienyl) -2,1,3-benzothiadiazole, 143 mg, 0.31 mmol) and 20% aqueous tetraethylammonium hydroxide (aq) 20% tetraethylammonium hydroxide solution, 3 And l), and tetrakis (triphenylphosphine) palladium 0 (tetrakis (triphenylphosphine) palladium0,5mg), placed and Aliquat 336, were stirred under reflux. After 72 hours, phenylboronic acid (0.05 g) was added and reacted for 3 hours, and then bromobenzene (bromobenzene, 0.12 g) was added and further reacted for 4 hours. The mixture was cooled to room temperature and poured into methanol, and then the solid was filtered. After Soxhlet extraction into acetone, hexane, and chloroform, the solid was precipitated again, and the solid was filtered.
Yield: 55%
Number average molecular weight: 18,400 g / mol
Weight average molecular weight: 43,400 g / mol

[Comparative Example 2. Synthesis of Copolymer 5]
3,6-Bis (4 ′, 4 ′, 5 ′, 5′-tetramethyl-1 ′, 3 ′, 2′-dioxaborolan-2′-yl) -N-9′-heptadecanyl in 3 ml of toluene Carbazole (3,6-Bis (4 ′, 4 ′, 5 ′, 5′-tetramethyl-1 ′, 3 ′, 2′-dioxabolan-2′-yl) -N-9′-heptadecanylcarbazole, 200 mg, 0. 304 mmol) and 4,7-bis (5-bromo-2-thienyl) -2,1,3-benzothiadiazole (4,7-bis- (5-bromo-2-thienyl) -2,1,3- benzothiadiazole, 139 mg, 0.304 mmol) and a 20% aqueous solution of tetraethylammonium hydroxide (aq. 20% tetraethylammonium hydro). A solution of 3 to 1), tetrakis (triphenylphosphine) palladium 0 (tetrakis (triphenylphosphine) palladium 0, 5 mg) and Aliquat 336 were added and stirred under reflux. After 72 hours, phenylboronic acid (0.05 g) was added and reacted for 3 hours, and then bromobenzene (bromobenzene, 0.12 g) was added and further reacted for 4 hours. The mixture was cooled to room temperature and poured into methanol, and then the solid was filtered. After Soxhlet extraction into acetone, hexane, and chloroform, the solid was precipitated again, and the solid was filtered.
Yield: 42%
Number average molecular weight: 4,500 g / mol
Weight average molecular weight: 6,100 g / mol

[Manufacture of organic solar cells and measurement of properties]
The prepared copolymer and PC ₇₁ BM ([6,6] -phenyl C ₆₁ butyric acid methyl ester) are dissolved in 1,2-dichlorobenzene (1,2-dichlorobenzene, DCB), and a composite solution ( composite solution). At this time, the concentration was adjusted to 1 to 2 wt%, and the organic solar cell had a structure of ITO / PEDOT: PSS / photoactive layer / LiF / Al. The glass substrate coated with ITO is ultrasonically cleaned using distilled water, acetone, and 2-propanol, and the surface of ITO is treated with ozone for 10 minutes, and then PEDOT: PSS (AI4083) is spin-coated to a thickness of 25 nm. And heat treated at 235 ° C. for 10 minutes. For coating the photoactive layer, the polymer-PC ₇₁ BM composite solution was filtered through a 0.45 μm PP syringe filter, spin-coated, heat-treated at 120 ° C. for 5 minutes, and 3 × Under a vacuum of 10 ⁻⁸ torr, 6 F of LiF was deposited using a thermal evaporator and then Al was deposited to a thickness of 120 nm. The photoelectric conversion characteristics of the organic solar cell produced as described above were measured under the condition of 100 mW / cm ² (AM1.5), and the results are shown in Table 1 below.
Characteristics of organic solar cells 1

  FIG. 2 is a graph showing a current-voltage curve of the organic solar cell.

  As shown in Table 1, Examples 2 to 4 including the copolymer including the first unit of Formula 1 include those of Comparative Example 1 and Formula 1 including the copolymer not including the first unit of Formula 1. It turns out that efficiency improves compared with the comparative example 2 containing the copolymer containing only a 1st unit.

  As shown in Table 1, it can be seen that the energy conversion efficiency is affected while the short-circuit current density and the fill factor are affected according to the molar ratio of the first unit of Chemical Formula 1.

  As a cause of such a phenomenon, 3,6-carbazole is contained, and the hole mobility in the photoactive layer of the organic solar cell is improved, resulting in symmetry with the electron mobility. It can be predicted that the conversion efficiency is improved.

[Manufacture of hole and electron mobility measuring elements and measurement of mobility]
The hole and electron mobility measuring element was manufactured under the same conditions as the organic solar cell element, and Pd was deposited instead of Al only for the second electrode.

The mobility measuring element manufactured as described above was measured with an IV characteristic analyzer in the dark, and the SCLC charge mobility was predicted using the following Equation 1.

Here, J is the current density, L is the thickness of the active layer film, mu _h is charge mobility, epsilon _r is the relative dielectric constant of the active layer film, epsilon _o is the vacuum dielectric constant, V is shown an internal voltage.
Hole of charge mobility measuring element, charge mobility

  As shown in FIGS. 2 to 5, the electron mobility / hole mobility in the device including the copolymer containing the first unit of Chemical Formula 1 is as follows. It can be seen that it is lower than the electron mobility / hole mobility in the included device. This means that the inclusion of the first unit of Chemical Formula 1 increases the hole mobility, and the charge mobility between the two charges is similar. It is well known to those skilled in the art having general knowledge that the similarity between two charge mobilities increases the energy conversion efficiency.

Claims (17)

A copolymer comprising: a first unit of the following chemical formula 1; a second unit of the following chemical formula 2; and a third unit of the following chemical formula 3.
(In chemical formulas 1-3,
o, p, q, and r are each an integer of 0 to 3,
s and t are each an integer of 0 to 4,
R _{a to} R _d are the same or different from each other, and each independently represents hydrogen; deuterium; halogen group; nitrile group; nitro group; imide group; amide group; hydroxy group; substituted or unsubstituted alkyl group; Substituted or unsubstituted alkoxy group; substituted or unsubstituted aryloxy group; substituted or unsubstituted alkylthioxy group; substituted or unsubstituted arylthioxy group; substituted or unsubstituted alkylsulfoxy Substituted or unsubstituted arylsulfoxy group; substituted or unsubstituted alkenyl group; substituted or unsubstituted silyl group; substituted or unsubstituted boron group; substituted or unsubstituted alkylamine group; substituted or unsubstituted Aralkylamine group; substituted or unsubstituted arylamine group; substituted or Substituted or unsubstituted aryl groups; substituted or unsubstituted fluorenyl groups; substituted or unsubstituted carbazole groups; and substituted or unsubstituted containing one or more of N, O, S atoms Or two adjacent substituents selected from the group consisting of heterocyclic groups can form a condensed ring;
R _{1 to} R ₇ are the same or different from each other, and are independently hydrogen, deuterium, halogen group, nitrile group, nitro group, imide group, amide group, hydroxy group, substituted or unsubstituted alkyl group, substituted or non-substituted Substituted or unsubstituted alkoxy group; substituted or unsubstituted aryloxy group; substituted or unsubstituted alkylthioxy group; substituted or unsubstituted arylthioxy group; substituted or unsubstituted alkylsulfoxy Substituted or unsubstituted arylsulfoxy group; substituted or unsubstituted alkenyl group; substituted or unsubstituted silyl group; substituted or unsubstituted boron group; substituted or unsubstituted alkylamine group; substituted or unsubstituted Aralkylamine group; substituted or unsubstituted arylamine group; substituted or Substituted or unsubstituted aryl groups; substituted or unsubstituted fluorenyl groups; substituted or unsubstituted carbazole groups; and substituted or unsubstituted containing one or more of N, O, S atoms Or two adjacent substituents selected from the group consisting of heterocyclic groups can form a condensed ring. )   2. The copolymer according to claim 1, wherein the first unit has a content exceeding 0 mol% and not more than 45 mol% in the total content of the copolymer. The copolymer according to claim 1, wherein the copolymer includes one represented by the following chemical formula 4.
(In Formula 4,
l is the mole fraction and is a real number where 0 <l ≦ 1,
m is a mole fraction, a real number of 0 ≦ m <1, and l + m = 1.
n is an integer from 1 to 10,000;
A is Formula 1 above,
B, C, and D are the same or different from each other, and each independently have the chemical formula 2 or 3,
At least one of B, C, and D is Formula 3. )   4. The copolymer according to claim 3, wherein B and D are represented by Formula 3, and C is Formula 2. 3. The copolymer according to claim 1, wherein the copolymer is represented by the following chemical formula 5.
(In chemical formula 5,
R _{a to} R _d and R _{1 to} R ₇ , o, p, q, r, s, and t are as defined in chemical formulas 1 to 3,
l is a mole fraction and is a real number of 0 <l ≦ 1, m is a mole fraction and is a real number of 0 ≦ m <1 and l + m = 1,
n is an integer of 1 to 10,000. ) The copolymer according to claim 1, wherein the copolymer includes a fourth unit represented by the following chemical formula 6 and a fifth unit represented by the chemical formula 7.
(In Chemical Formulas 6 and 7,
R ₁ is as defined in Chemical Formula 1,
R ₂ and R ₃ are as defined in Chemical Formula 2,
l is a mole fraction, and is a real number of 0 <l ≦ 1,
m is a mole fraction, and is a real number of 0 ≦ m <1, and l + m = 1. )   The copolymer according to any one of claims 1 to 6, wherein a terminal of the copolymer is an aryl group.   The copolymer according to any one of claims 1 to 6, wherein a terminal of the copolymer is a heterocyclic group.   The copolymer according to any one of claims 1 to 6, wherein the copolymer has a number average molecular weight of 500 to 1,000,000 g / mol.   The copolymer according to any one of claims 1 to 6, wherein the copolymer has a molecular weight distribution of 1 to 100.   A first electrode; a second electrode opposite to the first electrode; and one or more organic layers including a photoactive layer provided between the first electrode and the second electrode; One or more layers contain the copolymer of any one of Claims 1-6, The organic solar cell characterized by the above-mentioned.   The organic material layer further includes at least one selected from the group consisting of an electron donor and an electron acceptor, and the electron donor material is the copolymer. Organic solar cell.   The electron acceptor is selected from the group consisting of fullerene, fullerene derivatives, carbon nanotubes, carbon nanotube derivatives, bathocuproine, semiconducting elements, semiconducting compounds, and combinations thereof. The organic solar cell described.   The organic solar cell according to claim 12, wherein the electron acceptor is a C60 fullerene derivative or a C70 fullerene derivative.   The organic solar cell according to claim 12, wherein a mixing ratio of the copolymer and the electron acceptor is a weight ratio of 1: 0.5 to 1: 4.   15. The organic solar cell according to claim 14, wherein a mixing ratio of the copolymer and the C60 fullerene derivative or C70 fullerene derivative is a weight ratio of 1: 0.5 to 1: 4. Preparing a substrate;
Forming a first electrode in a region of the back surface of the substrate;
Forming an organic layer containing the copolymer according to any one of claims 1 to 6 on the first electrode; and forming a second electrode on the organic layer. A method for producing an organic solar cell.