KR102491798B1 - Polymer and organic solar cell comprising the same - Google Patents

Abstract

It relates to a polymer including a unit represented by Formula 1 below and an organic solar cell including the same.

Description

Polymer and organic solar cell containing the same {POLYMER AND ORGANIC SOLAR CELL COMPRISING THE SAME}

The present specification relates to a polymer and an organic solar cell comprising 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. A typical solar cell is made of a p-n junction by doping crystalline silicon (Si), an inorganic semiconductor. Electrons and holes generated by absorbing light diffuse to the p-n junction and are accelerated by the electric field to move to the electrode. The power conversion efficiency of this process is defined as the ratio of the power given to the external circuit and the solar power entered into the solar cell, and has been achieved up to 24% when measured under the currently standardized virtual solar irradiation conditions. However, since conventional inorganic solar cells already show limitations in economic feasibility and supply and demand in terms of materials, organic semiconductor solar cells that are easy to process, inexpensive, and have various functionalities are in the limelight 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 of such a solar cell, 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. One of the causes of electric charge loss is that generated electrons and holes disappear through recombination. Various methods have been proposed as a method for transferring the generated electrons or holes to the electrode without loss, but most of them require an additional process, which may increase manufacturing cost.

Two-layer organic photovoltaic cell (C.W.Tang, Appl. Phys. Lett., 48, 183. (1986))

The present specification provides a polymer and an organic solar cell comprising the same.

An exemplary embodiment of the present specification provides a polymer including a unit represented by Formula 1 below.

[Formula 1]

In Formula 1,

[D] is a conjugated monomer,

R1, R2, R10 and R11 are the same as or different from each other, and each independently a halogen group; A substituted or unsubstituted alkyl group; A substituted or unsubstituted cycloalkyl group; A substituted or unsubstituted alkoxy group; A substituted or unsubstituted aryl group; Or a substituted or unsubstituted heterocyclic group.

Another 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 one or more organic material layers including a photoactive layer,

At least one layer of the organic material layer provides an organic solar cell comprising the polymer.

The polymer according to one embodiment of the present specification may have effects of reducing a band gap and/or increasing an amount of light absorption. Accordingly, when applied to an organic solar cell, a high current value (Isc) and excellent efficiency can be exhibited.

The polymer according to one embodiment of the present specification has high efficiency and appropriate solubility at the same time, so there is an economical advantage in terms of time and / or cost when manufacturing a device.

The polymer according to an exemplary embodiment of the present specification may be used alone or in combination with other materials in an organic solar cell.

1 is a diagram illustrating an organic solar cell according to an exemplary embodiment of the present specification.
2 is a diagram showing MS measurement results of compound a-2.
3 is a diagram showing NMR measurement results of compound a-2.
4 is a diagram showing MS measurement results of compound a-3.
5 is a diagram showing NMR measurement results of compound a-3.
6 is a diagram showing current density according to voltage of an organic solar cell according to an exemplary embodiment of the present specification.

Hereinafter, this specification will be described in detail.

An exemplary embodiment of the present specification provides a polymer including a unit represented by Formula 1 above.

The polymer has excellent crystallinity by having region-regularity in which positions of R1, R2, R10 and R11 are substituted at certain positions.

In one embodiment of the present specification, the polymer has a -A-D- structure. In the polymer, [D] acts as a relatively electron donor (-D-), and the electron acceptor (-A-) part exhibits regioregularity, so it is determined without significantly affecting the structure and shape of [D]. can cause sexuality.

In the present specification, "regioregularity" means that substituents are provided in a certain direction in a structure in a polymer. For example, in Formula 1, R1 is substituted at a position relatively far from R10, and R10 and R11 are substituted in a direction toward [D].

In the present specification, "unit" means a repeating structure included in a polymer. That is, "unit" may refer to a structure included in a form of a divalent or higher group in a polymer by a polymerization reaction.

In the present specification, the meaning of "including a unit" means included in the main chain in the polymer.

는 다른 치환기, 단량체 또는 결합부에 결합되는 부위를 의미한다.In this specification,

Means a site to be bonded to another substituent, monomer or linking part.

In the present specification, a monomer may mean a repeating unit included in a polymer. For example, a conjugated monomer in a polymer may refer to a repeating unit derived from the conjugated monomer.

In this specification, “combination” means connecting several structures or connecting different types of structures.

In the present specification, "derived" means that a bond between at least two adjacent elements in a polymer is broken, or a new bond is generated while hydrogen or a substituent is removed, and the repeating unit derived from the conjugated monomer is the main chain of the polymer. And it may mean a unit forming one or more of the side chains. The unit may constitute a polymer by being included in a main chain in a polymer.

Examples of substituents in the present specification are described below, but are not limited thereto.

In this specification, the term "substituted or unsubstituted" means deuterium; halogen group; nitrile group; imide group; amide group; carbonyl group; ester group; hydroxy group; an alkyl group; cycloalkyl group; alkoxy group; alkenyl group; silyl group; amine group; aryl group; And it means that it is substituted with one or two or more substituents selected from the group consisting of a heterocyclic group, or is substituted with a substituent in which two or more substituents from among the above exemplified substituents are connected, or does not have any substituents. For example, "a substituent in which two or more substituents are connected" may be a biphenyl group. That is, the biphenyl group may be an aryl group, and may be interpreted as a substituent in which two phenyl groups are connected.

In the present specification, the halogen group may be 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 30. Specific examples include methyl, ethyl, propyl, n-propyl, isopropyl, butyl, n-butyl, isobutyl, tert-butyl, sec-butyl, 1-methyl-butyl, 1-ethyl-butyl, pentyl, n-pentyl , isopentyl, neopentyl, tert-pentyl, hexyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 4-methyl-2-pentyl, 3,3-dimethylbutyl, 2-ethylbutyl, heptyl, n -heptyl, 1-methylhexyl, octyl, n-octyl, tert-octyl, 1-methylheptyl, 2-ethylhexyl, 2-propylpentyl, n-nonyl, 2,2-dimethylheptyl, 1-ethyl-propyl, 1,1-Dimethyl-propyl, isohexyl, 4-methylhexyl, 4-methylnonane, 4-ethylnonane, 5-methylhexyl, 5-methylundecane, 5-ethylundecane, 5-propylundecane , 7-methylpentadecane, 7-ethylpentadecane, etc., but are not limited thereto.

In the present specification, the cycloalkyl group is not particularly limited, but preferably has 3 to 30 carbon atoms, specifically cyclopropyl, cyclobutyl, cyclopentyl, 3-methylcyclopentyl, 2,3-dimethylcyclopentyl, cyclohexyl , 3-methylcyclohexyl, 4-methylcyclohexyl, 2,3-dimethylcyclohexyl, 3,4,5-trimethylcyclohexyl, 4-tert-butylcyclohexyl, cycloheptyl, cyclooctyl, etc., but are limited thereto it is not going to be

In the present specification, the alkoxy group may be straight chain, branched chain or cyclic chain. The number of carbon atoms in the alkoxy group is not particularly limited, but is preferably 1 to 30 carbon atoms. Specifically, methoxy, ethoxy, n-propoxy, isopropoxy, i-propyloxy, n-butoxy, isobutoxy, tert-butoxy, sec-butoxy, n-pentyloxy, neopentyloxy, Isopentyloxy, n-hexyloxy, 3,3-dimethylbutyloxy, 2-ethylbutyloxy, n-octyloxy, n-nonyloxy, n-decyloxy, benzyloxy, p-methylbenzyloxy, etc. It may be, but is not limited thereto.

In the present specification, the aryl group may be monocyclic or polycyclic.

When the aryl group is a monocyclic aryl group, the number of carbon atoms is not particularly limited, but is preferably 6 to 30 carbon atoms. Specifically, the monocyclic aryl group may be a phenyl group, a biphenyl group, a terphenyl group, and the like, but is not limited thereto.

When the aryl group is a polycyclic aryl group, the number of carbon atoms is not particularly limited. It is preferable that it is 10-30 carbon atoms. Specifically, the polycyclic aryl group may be a naphthyl group, anthracenyl group, phenanthryl group, pyrenyl group, perylenyl group, chrysenyl group, fluorenyl group, and the like, but is not limited thereto.

In the present specification, the heterocyclic group includes at least one atom or heteroatom other than carbon, and specifically, the heteroatom may include at least one atom selected from the group consisting of O, N, Se, and S. The number of carbon atoms is not particularly limited, but preferably has 2 to 30 carbon atoms, and the heterocyclic group may be monocyclic or polycyclic. Examples of the heterocyclic group include a thiophene group, a furanyl group, a pyrrole group, an imidazolyl group, a thiazolyl group, an oxazolyl group, an oxadiazolyl group, a pyridyl group, a bipyridyl group, a pyrimidyl group, a triazinyl group, tria Zolyl group, acridyl group, pyridazinyl group, pyrazinyl group, quinolinyl group, quinazolinyl group, quinoxalinyl group, phthalazinyl group, pyrido pyrimidyl group, pyrido pyrazinyl group, pyrazino pyrazinyl group , Isoquinolinyl group, indolyl group, carbazolyl group, benzoxazolyl group, benzimidazolyl group, benzothiazolyl group, benzocarbazolyl group, benzothiophene group, dibenzothiophene group, benzofuranyl group, Examples include a phenanthroline group, a thiazolyl group, an isoxazolyl group, an oxadiazolyl group, a thiadiazolyl group, a phenothiazinyl group, and a dibenzofuranyl group, but are not limited thereto.

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

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

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

In the present specification, the ester group may be substituted with an alkyl group having 1 to 25 carbon atoms, a cycloalkyl group having 3 to 30 carbon atoms, or an aryl group having 6 to 30 carbon atoms. Specifically, it may be a compound of the following structural formula, but is not limited thereto.

In the present specification, the alkenyl group may be linear or branched, and the number of carbon atoms is not particularly limited, but is preferably 2 to 30. Specific examples include vinyl, 1-propenyl, isopropenyl, 1-butenyl, 2-butenyl, 3-butenyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 3-methyl-1- Butenyl, 1,3-butadienyl, allyl, 1-phenylvinyl-1-yl, 2-phenylvinyl-1-yl, 2,2-diphenylvinyl-1-yl, 2-phenyl-2-( naphthyl-1-yl)vinyl-1-yl, 2,2-bis(diphenyl-1-yl)vinyl-1-yl, stilbenyl group, styrenyl group, etc., but are not limited thereto.

In the present specification, the silyl group is specifically a trimethylsilyl group, a triethylsilyl group, a t-butyldimethylsilyl group, a vinyldimethylsilyl group, a propyldimethylsilyl group, a triphenylsilyl group, a diphenylsilyl group, a phenylsilyl group, and the like. However, it is not limited thereto.

In the present specification, the amine group is -NH ₂ ; monoalkylamine group; Dialkylamine group; N-alkyl arylamine group; monoarylamine group; Diaryl amine group; N-arylheteroarylamine group; It may be selected from the group consisting of an N-alkylheteroarylamine group, a monoheteroarylamine group, and a diheteroarylamine group, and the number of carbon atoms is not particularly limited, but is preferably 1 to 30. Specific examples of the amine group include a methylamine group, a dimethylamine group, an ethylamine group, a diethylamine group, a phenylamine group, a naphthylamine group, a biphenylamine group, an anthracenylamine group, and a 9-methyl-anthracenylamine group. , Diphenylamine group, ditolylamine group, N-phenyltolylamine group, triphenylamine group, N-phenylbiphenylamine group; N-phenylnaphthylamine group; N-biphenyl naphthylamine group; N-naphthylfluorenylamine group; N-phenylphenanthrenylamine group; N-biphenylphenanthrenylamine group; N-phenylfluorenylamine group; N-phenylterphenylamine group; N-phenanthrenylfluorenylamine group; N-biphenylfluorenylamine group and the like, but are not limited thereto.

In the present specification, the description of the alkenyl group described above may be applied except that the alkenylene group is a divalent group.

In the present specification, the description of the aryl group described above may be applied except that the arylene group is a divalent group.

In the present specification, the description of the above-described heterocyclic group may be applied except that the divalent heterocyclic group is a divalent group.

In one embodiment of the present specification, R1, R2, R10 and R11 are the same as or different from each other, and each independently a halogen group; A substituted or unsubstituted alkyl group; A substituted or unsubstituted cycloalkyl group; A substituted or unsubstituted alkoxy group; A substituted or unsubstituted aryl group; Or a substituted or unsubstituted heterocyclic group.

In one embodiment of the present specification, R1, R2, R10 and R11 are the same as or different from each other, and each independently a halogen group; Or a substituted or unsubstituted alkyl group.

In one embodiment of the present specification, R1 and R2 are the same as or different from each other, and each independently represents a substituted or unsubstituted alkyl group.

In one embodiment of the present specification, R1 and R2 are the same as or different from each other, and each independently represents an alkyl group having 1 to 30 carbon atoms.

In one embodiment of the present specification, R1 and R2 are the same as or different from each other, and each independently represents a branched chain alkyl group having 1 to 30 carbon atoms.

In one embodiment of the present specification, R10 and R11 are the same as or different from each other, and each independently represents a halogen group.

In one embodiment of the present specification, R10 and R11 are each fluorine.

In one embodiment of the present specification, [D] is a conjugated monomer.

In one embodiment of the present specification, the conjugated monomer includes a combination of one or two or more of a substituted or unsubstituted alkenylene group, a substituted or unsubstituted arylene group, and a substituted or unsubstituted divalent heterocyclic group. do.

In one embodiment of the present specification, the conjugated monomer includes any one or a combination of two or more of the following structures.

In the above structure,

a, a', b, b', c, c', d and d' are each an integer from 1 to 5;

When a, a', b, b', c, c', d and d' are each 2 or more, the substituents in parentheses are the same as or different from each other,

X10 to X29 are the same as or different from each other, and are each independently S, O, Se, Te, NR _a , CR _a R _b , SiR _a R _b , PR _a or GeR _a R _b ,

R110 to R139, R _a and R _b are the same as or different from each other, and each independently hydrogen; halogen group; A substituted or unsubstituted alkyl group; A substituted or unsubstituted cycloalkyl group; A substituted or unsubstituted alkoxy group; A substituted or unsubstituted aryl group; Or a substituted or unsubstituted heterocyclic group.

In one embodiment of the present specification, the conjugated monomer is any one of the following structures.

In the above structure,

a, a', b and b' are each an integer from 1 to 5;

When a, a', b and b' are each 2 or more, the substituents in parentheses are the same as or different from each other,

X10 to X15, X24, X25 and X27 to X29 are the same as or different from each other, and are each independently S, O, Se, Te, NR _a , CR _a R _b , SiR _a R _b , PR _a or GeR _a R _b , ,

R110 to R115, R126 to R131, R134 to R139, R _a and R _b are the same as or different from each other, and each independently hydrogen; halogen group; A substituted or unsubstituted alkyl group; A substituted or unsubstituted cycloalkyl group; A substituted or unsubstituted alkoxy group; A substituted or unsubstituted aryl group; Or a substituted or unsubstituted heterocyclic group.

In one embodiment of the present specification, each of X10 to X15, X24, X25, and X27 to X29 is S.

In one embodiment of the present specification, R110 to R115 are the same as or different from each other, and each independently hydrogen; Or a substituted or unsubstituted alkyl group.

In one embodiment of the present specification, R110 to R115 are the same as or different from each other, and each independently hydrogen; or a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms.

In one embodiment of the specification, R110 and R111 are the same as or different from each other, and each independently represents a branched chain alkyl group having 1 to 30 carbon atoms.

In one embodiment of the specification, the R112 to R115 are the same as or different from each other, and each independently hydrogen; or an alkyl group having 1 to 20 carbon atoms.

In one embodiment of the specification, the R112 to R115 are the same as or different from each other, and each independently hydrogen; or an alkyl group having 1 to 10 carbon atoms.

In one embodiment of the specification, the R126 to R131 are the same as or different from each other, and each independently hydrogen; Or a substituted or unsubstituted alkyl group.

In one embodiment of the specification, the R126 to R131 are the same as or different from each other, and each independently hydrogen; or a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms.

In one embodiment of the specification, R126 and R127 are the same as or different from each other, and each independently represents a branched chain alkyl group having 1 to 30 carbon atoms.

In one embodiment of the specification, R126 and R127 are the same as or different from each other, and each independently represents a branched chain alkyl group having 1 to 20 carbon atoms.

In one embodiment of the specification, each of R128 to R131 is hydrogen.

In one embodiment of the present specification, R134 to R139 are the same as or different from each other, and each independently hydrogen; A substituted or unsubstituted alkyl group; Or a substituted or unsubstituted alkoxy group.

In one embodiment of the present specification, R134 and R139 are identical to each other.

In one embodiment of the present specification, R135 and R138 are identical to each other.

In one embodiment of the present specification, R136 and R137 are identical to each other.

In one embodiment of the present specification, R134 and R139 are each hydrogen; Or a substituted or unsubstituted alkoxy group.

In one embodiment of the present specification, R135 and R138 are each hydrogen.

In one embodiment of the present specification, R136 and R137 are each hydrogen; Or a substituted or unsubstituted alkyl group.

In one embodiment of the present specification, R136 and R137 are each hydrogen; or an alkyl group having 1 to 30 carbon atoms.

In one embodiment of the present specification, R136 and R137 are each hydrogen; or an alkyl group having 1 to 20 carbon atoms.

In one embodiment of the present specification, the unit represented by Chemical Formula 1 includes any one of the following structures.

In one embodiment of the present specification, the polymer includes n units represented by Formula 1, and n is an integer from 1 to 10,000.

In one embodiment of the present specification, n is an integer from 2 to 5,000.

In one embodiment of the present specification, n is an integer from 5 to 1,000.

In one embodiment of the present specification, the terminal group of the polymer is a substituted or unsubstituted aryl group; Or a substituted or unsubstituted heterocyclic group.

In one embodiment of the present specification, the terminal group of the polymer is a substituted or unsubstituted thiophene group; or a substituted or unsubstituted phenyl group.

An exemplary embodiment of the present specification includes 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 one or more organic material layers including a photoactive layer,

At least one layer of the organic material layer provides an organic solar cell comprising the polymer.

In one embodiment of the present specification, the photoactive layer includes the polymer.

In one embodiment of the present specification, the photoactive layer includes an electron donor and an electron acceptor, and the electron donor includes the polymer.

In one embodiment of the present specification, the electron acceptor may be selected from the group consisting of fullerenes, fullerene derivatives, vasocuproin, semiconducting elements, semiconducting compounds, and combinations thereof. Specifically, the electron acceptor material may be PC ₆₀ BM (phenyl C ₆₀ -butyric acid methyl ester), PC ₆₁ BM (phenyl C ₆₁ -butyric acid methyl ester) or PC ₇₁ BM (phenyl C ₇₁ -butyric acid methyl ester) can

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

A bulk heterojunction means that an electron donor material and an electron acceptor material are mixed with each other in the photoactive layer.

In one embodiment of the present specification, the electron donor and electron acceptor may be mixed in a weight ratio of 1:10 to 10:1. Specifically, the electron donor and electron acceptor may be mixed in a weight ratio of 1:1 to 1:10, and more specifically, the electron donor and electron acceptor may be mixed in a weight ratio of 1:1 to 1:5. If necessary, the electron donor and electron acceptor may be mixed in a weight ratio of 1:1 to 1:3.

In one embodiment of the present specification, the photoactive layer has a bilayer structure including an n-type organic compound layer and a p-type organic compound layer, and the p-type organic compound layer includes the polymer.

In one 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 organic materials having multiple functions at the same time.

In one embodiment of the present specification, the organic solar cell includes one or two or more organic material layers selected from the group consisting of a hole injection layer, a hole transport layer, a hole blocking layer, a charge generating layer, an electron blocking layer, an electron injection layer, and an electron transport layer. more includes

In one embodiment of the present specification, the organic material layer includes a hole transport layer, a hole injection layer, or a layer that simultaneously transports and injects holes, and the hole transport layer, the hole injection layer, or the layer that simultaneously transports and injects holes including the above polymers.

In another exemplary embodiment, the organic material layer includes an electron injection layer, an electron transport layer, or a layer that simultaneously injects and transports electrons, and the electron injection layer, the electron transport layer, or a layer that simultaneously injects and transports electrons including the above polymers.

In one embodiment of the present specification, the organic solar cell 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 organic solar cell further includes a substrate, an electron transport layer, and a hole transport layer.

1 is according to an exemplary embodiment of the present specification including a substrate 10, a first electrode 20, an electron transport layer 30, a photoactive layer 40, a hole transport layer 50 and a second electrode 60 It is a diagram showing an organic solar cell.

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

In one embodiment of the present specification, the organic solar cell has a normal structure. In the normal structure, a substrate, a first electrode, a hole transport layer, an organic material layer including a photoactive layer, an electron transport layer, and a second electrode may be sequentially stacked.

In one embodiment of the present specification, the organic solar cell has an inverted structure. In the inverted structure, a substrate, a first electrode, an electron transport layer, an organic material layer including a photoactive layer, a hole transport layer, and a second electrode may be sequentially stacked.

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

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

The method of forming the first electrode is not particularly limited, but is applied to one surface of the substrate or in the form of a film using, for example, sputtering, E-beam, thermal evaporation, spin coating, screen printing, inkjet printing, doctor blade or gravure printing. It can be formed by coating.

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

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

Through the surface modification as described above, the junction surface potential can be maintained at a level suitable for the surface potential of the photoactive layer. In addition, when reforming, it is easy to form a polymer thin film on the first electrode, and the quality of the thin film may be improved.

Pretreatment techniques for forming the first electrode include a) surface oxidation using parallel plate type discharge, b) surface oxidation through ozone generated using UV rays in a vacuum state, and c) by plasma There is a method of oxidation using generated oxygen radicals.

One of the above methods may be selected according to the state of the first electrode or substrate. However, regardless of which method is used, it is desirable to prevent oxygen escape from the surface of the first electrode or the substrate and to suppress the remaining moisture and organic matter as much as possible. At this time, the practical effect of the pretreatment 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, dried well, put into a chamber, and a UV lamp is operated to generate oxygen gas by reacting with UV light to generate ozone. The patterned ITO substrate can be cleaned.

However, the surface modification method 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 the method oxidizes the substrate.

The second electrode may be a metal having a low 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; It may be a multi-layered material such as LiF/Al, LiO ₂ /Al, LiF/Fe, Al:Li, Al:BaF ₂ , Al:BaF ₂ :Ba, but is not limited thereto.

The second electrode may be deposited and formed inside a thermal evaporator exhibiting a vacuum degree of 5x10 ^{- 7} torr or less, but is not limited to this method.

The material of the hole transport layer and/or the electron transport layer 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 is PEDOT: PSS (Poly (3,4-ethylenedioxythiophene) doped with poly (styrenesulfonic acid)), molybdenum oxide (MoO _x ) as a hole transport material; vanadium oxide (V ₂ O ₅ ); nickel oxide (NiO); And tungsten oxide (WO _x ) It may include, but is not limited to these.

The electron transport layer may be electron-extracting metal oxides as an electron transport material, specifically, a metal complex of 8-hydroxyquinoline; Complexes containing Alq ₃ ; metal complexes including Liq; LiF; Ca; titanium oxide (TiO _x ); zinc oxide (ZnO); and cesium carbonate (Cs ₂ CO ₃ ), but may include, but are not limited thereto.

In one embodiment of the present specification, the photoactive layer is obtained by dissolving a photoactive material such as an electron donor and/or an electron acceptor in an organic solvent, and then applying the solution by spin coating, dip coating, screen printing, spray coating, doctor blade, brush painting, etc. It can be formed by the method of, but is not limited only to these methods.

The preparation method of the polymer and the manufacture of an organic solar cell including the same will be described in detail in Preparation Examples and Examples below. However, the following examples are intended to illustrate the present specification, and the scope of the present specification is not limited thereto.

Preparation Example 1. Preparation of Polymer 1

(1) Preparation of compound a-2

Dissolve compound a-1 (2.95g, 4.1mmol) in 50mL toluene, add tetrakis(triphenylphosphine)palladium(0) catalyst (Pd(PPh ₃ ) ₄ ) (58mg, 0.05mmol), Reacted at 110 °C for 48 hours. After cooling, the resulting residue was precipitated in methanol, filtered and washed with water. Then, the solvent was evaporated through a drying process, and the residual product was purified through flash chromatography (eluent: hexane: dichloromethane = 9.5: 0.5). Thereafter, washed with methanol and acetone, and dried under vacuum conditions for 24 hours to obtain 1.85 g of compound a-2.

2 is a diagram showing MS measurement results of compound a-2.

3 is a diagram showing NMR measurement results of compound a-2.

(2) Preparation of compound a-3

After filling a 100mL flask with compound a-2 (0.76g, 0.68mmol) and 40mL of tetrahydrofuran (THF), the mixture was cooled to 0°C. Then, N-bromosuccinimide (NBS) (0.28g, 1.57mmol) was added and stirred for 24 hours. After the reaction, extraction was performed with methylene chloride, and the synthesized organic material layer was sufficiently washed with water. Residual water was removed from the organic extract with anhydrous MgSO ₄ to obtain 0.51 g of compound a-3.

4 is a diagram showing MS measurement results of compound a-3.

5 is a diagram showing NMR measurement results of compound a-3.

(3) Preparation of Polymer 1

12mL of toluene, 3mL of dimethylformamide (DMF), compound a-3 (0.22mmol) and compound A (0.22mmol) were put in a 100mL flask under a nitrogen (N ₂ ) atmosphere, and nitrogen was bubbled for 30 minutes. Thereafter, tetrakis(triphenylphosphine)palladium(0) catalyst (Pd(PPh ₃ ) ₄ ) (2 mol%) was added and stirred at 110° C. for 48 hours. After adding 0.5mL of Br-Benzotrifluoride, the mixture was stirred for 12 hours and cooled to room temperature. Then, the product was poured into chloroform, passed through a short column with silica, poured into a mixed solution (180 mL methanol + 20 mL HCl (2M concentration)), and the precipitate was filtered. Thereafter, the product was subjected to soxhlet extraction in the order of methanol, acetone, hexane, methylene chloride and chlorobenzene. The extract extracted with chlorobenzene was put into methanol to form a precipitate. The resulting precipitate was collected, filtered, and dried under vacuum conditions to obtain 98 mg of Polymer 1. At this time, by measuring the number average molecular weight (Mn), it was confirmed that polymer 1 was prepared. (Yield: 30%, Mn=9,200 g/mol, PDI=2.1)

Preparation Example 2. Preparation of Polymer 2

12mL of toluene, 3mL of DMF, compound a-3 (0.22mmol), and compound B (0.22mmol) were put in a 100mL flask under a nitrogen (N ₂ ) atmosphere, followed by nitrogen bubbling for 30 minutes. Thereafter, tetrakis(triphenylphosphine)palladium(0) catalyst (Pd(PPh ₃ ) ₄ ) (2 mol%) was added and stirred at 110° C. for 48 hours. After adding 0.5mL of Br-Benzotrifluoride, the mixture was stirred for 12 hours and cooled to room temperature. Then, the product was poured into chloroform, passed through a short column with silica, poured into a mixed solution (180 mL methanol + 20 mL HCl (2M concentration)), and the precipitate was filtered. Thereafter, the product was subjected to soxhlet extraction in the order of methanol, acetone, hexane, methylene chloride and chlorobenzene. The extract extracted with chlorobenzene was put into methanol to form a precipitate. The resulting precipitate was collected, filtered, and dried under vacuum conditions to obtain 344 mg of Polymer 2. At this time, by measuring the number average molecular weight (Mn), it was confirmed that polymer 2 was prepared. (Yield: 88%, Mn=27,500g/mol, PDI=1.9)

Preparation Example 3. Preparation of Polymer 3

Compound a-3 (0.22mmol) and compound C (0.22mmol) were added and nitrogen was bubbled for 30 minutes. Thereafter, tetrakis(triphenylphosphine)palladium(0) catalyst (Pd(PPh ₃ ) ₄ ) (2 mol%) was added and stirred at 110° C. for 48 hours. After adding 0.5mL of Br-Benzotrifluoride, the mixture was stirred for 12 hours and cooled to room temperature. Then, the product was poured into chloroform, passed through a short column with silica, poured into a mixed solution (180 mL methanol + 20 mL HCl (2M concentration)), and the precipitate was filtered. Thereafter, the product was subjected to soxhlet extraction in the order of methanol, acetone, hexane, methylene chloride and chlorobenzene. The extract extracted with chlorobenzene was put into methanol to form a precipitate. The resulting precipitate was collected, filtered, and dried under vacuum conditions to obtain 327 mg of Polymer 3. At this time, by measuring the number average molecular weight (Mn), it was confirmed that polymer 3 was prepared. (Yield: 75%, Mn=22,100g/mol, PDI=1.7)

Preparation Example 4. Preparation of Polymer 4

12mL of toluene, 3mL of DMF, compound a-3 (0.22mmol) and compound D (0.22mmol) were put in a 100mL flask under a nitrogen (N2) atmosphere, and nitrogen was bubbled for 30 minutes. Thereafter, tetrakis(triphenylphosphine)palladium(0) catalyst (Pd(PPh ₃ ) ₄ ) (2 mol%) was added and stirred at 110° C. for 48 hours. After adding 0.5mL of Br-Benzotrifluoride, the mixture was stirred for 12 hours and cooled to room temperature. Then, the product was poured into chloroform, passed through a short column with silica, poured into a mixed solution (180 mL methanol + 20 mL HCl (2M concentration)), and the precipitate was filtered. Thereafter, the product was subjected to soxhlet extraction in the order of methanol, acetone, hexane, methylene chloride and chlorobenzene. The extract extracted with chlorobenzene was put into methanol to form a precipitate. The resulting precipitate was collected, filtered, and dried under vacuum conditions to obtain 280 mg of Polymer 4. At this time, by measuring the number average molecular weight (Mn), it was confirmed that polymer 4 was prepared. (Yield: 88%, Mn=24,300 g/mol, PDI=1.6).

Preparation Example 5. Preparation of Polymer 5

12mL of toluene, 3mL of DMF, compound a-3 (0.22mmol) and compound E (0.22mmol) were put in a 100mL flask under a nitrogen (N2) atmosphere, and nitrogen was bubbled for 30 minutes. Thereafter, tetrakis(triphenylphosphine)palladium(0) catalyst (Pd(PPh3)4) (2 mol%) was added and stirred at 110°C for 48 hours. After adding 0.5 mL of Br-Benzotrifluoride, the mixture was stirred for 12 hours and cooled to room temperature. Then, the product was poured into chloroform, passed through a short column with silica, poured into a mixed solution (180 mL methanol + 20 mL HCl (2M concentration)), and the precipitate was filtered. Thereafter, the product was subjected to soxhlet extraction in the order of methanol, acetone, hexane, methylene chloride and chlorobenzene. The extract extracted with chlorobenzene was put into methanol to form a precipitate. The resulting precipitate was collected, filtered, and dried under vacuum conditions to obtain 295 mg of Polymer 5. At this time, by measuring the number average molecular weight (Mn), it was confirmed that polymer 5 was produced. (Yield: 84%, Mn=29,100g/mol, PDI=1.5)

Example 1.

Polymer 1 prepared in Preparation Example 1 was used as an electron donor and PC ₆₁ BM was used as an electron acceptor and dissolved in chlorobenzene (CB) at a ratio of 1:2 to prepare a composite solution. At this time, the concentration was adjusted to 2.0 wt%, and the organic solar cell had a structure of ITO/ZnO/photoactive layer/MoO ₃ /Ag. The ITO-coated glass substrate was ultrasonically cleaned using distilled water, acetone, and 2-propanol, and the ITO surface was treated with ozone for 10 minutes, followed by spin-coating with a ZnO precursor solution and heat treatment at 120° C. for 10 minutes. Thereafter, the composite solution was filtered through a 0.45 μm PTFE syringe filter and then spin-coated to form a photoactive layer. Thereafter, MoO 3 was deposited on the photoactive layer to a thickness of 5 nm to 20 nm at a rate of 0.4 Å/s in a thermal evaporator to prepare a hole transport layer. Thereafter, Ag was deposited at a thickness of 10 nm on the hole transport layer at a rate of 1 Å/s inside a thermal evaporator to prepare an organic solar cell.

Example 2.

An organic solar cell was manufactured in the same manner as in Example 1, except that Polymer 2 was used instead of Polymer 1 in Example 1.

Example 3.

An organic solar cell was manufactured in the same manner as in Example 1, except that Polymer 3 was used instead of Polymer 1 in Example 1.

Example 4.

An organic solar cell was manufactured in the same manner as in Example 1, except that Polymer 4 was used instead of Polymer 1 in Example 1.

Example 5.

An organic solar cell was manufactured in the same manner as in Example 1, except that Polymer 5 was used instead of Polymer 1 in Example 1.

The photoelectric conversion characteristics of the organic solar cells prepared in Examples 1 to 5 were measured under the condition of 100 mW/cm ² (AM 1.5), and the results are shown in Table 1 and FIG. 6.

V _oc
(V) J _sc
(mA/cm ² ) FF η
(%) Example 1 0.74 13.8 67 6.84 Example 2 0.72 13.1 57 5.38 Example 3 0.73 13.3 54 5.24 Example 4 0.72 13.6 68 6.65 Example 5 0.72 13.3 69 6.61

In Table 1, Voc means open-circuit voltage, Jsc means short-circuit current, FF means fill factor, and η means 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 are, the higher the efficiency of the solar cell is. In addition, 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 can be obtained by dividing these three values by the intensity of the irradiated light, and a higher value is preferable.

From Table 1, it can be confirmed that the polymer according to an exemplary embodiment of the present specification can act as an electron donor in the photoactive layer of an organic solar cell.

10: substrate
20: first electrode
30: electron transport layer
40: photoactive layer
50: hole transport layer
60: second electrode

Claims (8)

A polymer comprising a unit represented by Formula 1 below:
[Formula 1]

In Formula 1,
R1 and R2 are the same as or different from each other, and are each independently an alkyl group,
R10 and R11 are the same as or different from each other, and are each independently a halogen group,
[D] is any one of the following structures,

In the above structure,
a, a', b and b' are each an integer from 1 to 5;
When a, a', b and b' are each 2 or more, the substituents in parentheses are the same as or different from each other,
X10 to X15, X24, X25 and X27 to X29 are each S,
R110 to R115, R126 to R131 and R134 to R139 are the same as or different from each other, and each independently represent hydrogen, an alkyl group or an alkoxy group. delete delete The method of claim 1,
A polymer in which the unit represented by Formula 1 includes any one of the following structures:

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 one or more organic material layers including a photoactive layer,
An organic solar cell wherein at least one layer among the organic material layers includes the polymer according to claim 1 or 4. The method of claim 5,
The photoactive layer includes an electron donor and an electron acceptor,
The electron donor is an organic solar cell comprising the polymer. The method of claim 6,
The organic solar cell wherein the electron donor and electron acceptor have a bulk heterojunction structure. The method of claim 5,
The organic solar cell further comprises one or two or more organic material layers selected from the group consisting of a hole injection layer, a hole transport layer, a hole blocking layer, a charge generation layer, an electron blocking layer, an electron injection layer, and an electron transport layer. .

Images