KR101535066B1 - Double junction organic photovoltaic device fabricated using organic semiconductor compound, and organic electronic device that contains it - Google Patents

Abstract

TECHNICAL FIELD The present invention relates to an organic semiconductor compound of a layered organic solar cell having excellent electrical properties, a method of producing the same, and an organic electronic device containing the organic semiconductor compound. The organic semiconductor compound has high thermal stability, And thus exhibits excellent performance in the layered organic solar cell device.

Description

TECHNICAL FIELD [0001] The present invention relates to an organic semiconductor compound for two stacked organic solar cell elements, and an organic electronic device comprising the same. More particularly, the present invention relates to a double junction organic photovoltaic device fabricated using an organic semiconductor compound,

The present invention relates to an organic semiconductor compound suitable for a layered organic solar cell device, and a method for producing the organic semiconductor compound. More particularly, the present invention relates to an organic semiconductor compound containing fluorine, a method for producing the organic semiconductor compound, and an organic electronic device including the same.

In 2009, the photovoltaic industry has installed more than 6GW in the world, forming an independent industrial country of $ 30 billion market, and it is expected to continue to grow rapidly until mid-21st century.

Current major products are crystalline silicon solar cells, which have overwhelming use in the solar power market. In recent years, however, market share of inorganic thin film solar cells such as a-Si, CdTe and CIGS has been steadily increasing. Respectively.

In addition, organic solar cells represented by dye-sensitized and organic thin-film type are not yet entering the market in earnest, but they can lead the ubiquitous solar era, which is expected in the future by promoting cheap material cost, process cost, and light, Another possibility is presented.

However, if the efficiency is higher than 10% in the future, it will be used for building integrated photovoltaic system (BIPV), which creates a beautiful appearance by installing it on a window or a balcony of a building It is expected to be largely written on. In the future, it is expected to serve as a diverse energy source supporting various flexible displays, military, indoor, and disposable solar cells.

In 1986, Eastman Kodak's CW Tang produced copper phthalocyanine (CuPc) and perylenetetracarboxylic acid (CuPc) in 1986. However, in the 1970s when the possibility of organic solar cells was first suggested, efficiency was too low to be practical. (perylene tetracarboxylic acid) derivatives, the interest and research on organic solar cell have been rapidly increasing and the development has been made. In 1995, Yu and Yu introduced the concept of bulk-heterojunction (BHJ). Fullerene derivatives such as PCBM, which have improved solubility, have been developed as n-type semiconductor materials. there was.

In particular, the research of organic solar cells has rapidly increased since 2000, and polymer solar cells capable of introducing photoactive by a solution process have introduced a bulk-hetero junction concept with PCBM in the early 2000s, By using P3HT as a photoactive layer, efficiency of 4 ~ 6% has been generally obtained. As a result, attempts to develop new materials and device structures by attracting attention from academia and industry have been made since 2005 It started in earnest.

In the case of polymer solar cells, improvement of efficiency is prominent due to new device configuration and process conditions change. In order to replace existing materials, donor materials with low bandgap and high charge mobility The development of new acceptor materials continues to require research and development.

Up to now, 9% efficiency has been reported worldwide using a single-layer organic solar cell device.

However, a tandem organic solar cell using an electron donor material that absorbs different light in each single layer has been actively studied. It has been reported that the performance of a single layer organic solar cell is more than twice that of a single layer organic solar cell by implementing the sum of the open voltages in the two single layers, the average short circuit current and the FF. Generally, a stacked organic solar cell is divided into a bottom cell and a top cell. In the lower layer, an electron donor material and an electron acceptor material exhibiting absorption of 300-600 nm are used, and an electron beam material and an acceptor material of 600-1000 nm are used in the upper layer. Most of the progress of the research has been reported on a layered organic solar cell using P3HT: ICBA as a lower layer and a novel material having a lower band gap as an upper layer.

The present invention relates to a high performance laminated organic solar cell lower layer (bottom

lt; RTI ID = 0.0 > a < / RTI > cell.

The present invention also provides a method for producing the organic semiconductor compound of the present invention.

The present invention also provides a layered organic electronic device containing the organic semiconductor compound of the present invention.

The present invention relates to a P3HT-based material having an intermediate band gap

To provide an organic semiconductor compound, and more particularly, to an organic semiconductor compound containing fluorine.

The organic semiconductor compound of the present invention may be any one compound represented by the following general formula (1) or (2) or two or more compounds.

[In the formulas (1) and (2)

D is C ₆ -C ₃₀ arylene or C ₃ -C ₃₀ heteroarylene;

X is Se, and O or NR5, R5 is hydrogen, C ₁ -C ₃₀ alkyl, C ₁ -C ₃₀ alkoxy group, C ₁ -C ₃₀ alkylthio, C ₁ -C ₃₀ alkoxyl heteroarylene, C ₆ - C ₃₀ ahreu C ₁ -C ₃₀ alkyl group;

Ra and Rb are independently hydrogen, C ₁ -C ₃₀ alkyl, C ₁ -C ₃₀ alkoxy group, C ₁ -C ₃₀ alkylthio, C ₁ -C ₃₀ alkoxyl heteroarylene, C ₆ -C ₃₀ ahreu each other C ₁ is -C ₃₀ alkyl, said C ₁ -C ₃₀ alkyl, C ₆ -C ₃₀ ahreu C ₁ -C ₃₀ alkyl is C ₁ -C ₃₀ alkyl, C ₂ -C ₃₀ alkenyl, C ₂ -C ₃₀ alkynyl, and C ₁ -C be further substituted with one or more substituents selected at _30, and alkoxy;

and n is an integer of 1 to 2000.]

The organic semiconductor compound of the present invention introduces an electron acceptor containing fluorine to synthesize an organic semiconductor compound that can be used for a lower layer of a layered organic solar cell element through copolymerization with various electron hosts.

In particular, the organic semiconductor compound synthesized in the present invention exhibited an intermediate band gap similar to that of P3HT and exhibited a low HOMO energy level in the molecule. In addition, it was possible to realize a favorable nano structure through copolymerization with various electron hosts, and the performance of the layered organic solar cell device using the same was excellent.

Furthermore, the present invention was firstly invented as a new organic semiconductor compound that can replace P3HT in a layered organic solar cell, and it has been found that the performance of the organic solar electronic device can be significantly improved by using the same.

The substituents comprising " alkyl ", " alkoxy " and other " alkyl " moieties described in this invention encompass both linear and branched forms. &Quot; Aryl " according to the present invention suitably includes a single or fused ring system containing 4 to 7, preferably 5 or 6, ring atoms, and a form in which a plurality of aryls are connected by a single bond . Specific examples include, but are not limited to, phenyl, naphthyl, biphenyl, anthryl, indenyl, fluorenyl, and the like. "Heteroaryl" in the present invention includes 1 to 4 heteroatoms selected from B, N, O, S, P (= O), Si and P as aromatic ring skeletal atoms and the remaining aromatic ring skeletal atoms are carbon Means a 5 to 6 membered monocyclic heteroaryl and a polycyclic heteroaryl condensed with at least one benzene ring and may be partially saturated. The heteroaryl in the present invention may also include a form in which at least one heteroaryl is connected to a single bond, and a 5- to 6-membered monocyclic heteroaryl may be fused and partially saturated. Specific examples include, but are not limited to, pyrrolyl, thionyl, 2,5-dimethylpyrrolopyrrole-1,4-diyonyl, and the like.

D in Formula 1 and Formula 2 according to an embodiment of the present invention may independently be one or more selected from the following structures.

[In the above formula,

R 1 and R 2 are independently of each other hydrogen, TIPS (triisopropylsilylethynyl), C ₁ -C ₃₀ alkoxy, C ₁ -C ₃₀ alkyl and C ₁ -C ₃₀ alkylheteroaryl.

The formula (1) and formula (2) according to an embodiment of the present invention may be independently represented by the following formulas, but are not limited thereto.

[In the formula,

X is Se, and O or NR5, R5 is hydrogen, C ₁ -C ₃₀ alkyl, C ₁ -C ₃₀ alkoxy group, C ₁ -C ₃₀ alkylthio, C ₁ -C ₃₀ alkoxyl heteroarylene, C ₆ - C ₃₀ ahreu C ₁ -C ₃₀ alkyl group;

R 1 and R 2 are independently of each other hydrogen, TIPS (triisopropylsilylethynyl), C ₁ -C ₃₀ alkoxy, C ₁ -C ₃₀ alkyl and C ₁ -C ₃₀ alkylheteroaryl;

Ra and Rb are independently hydrogen, C ₁ -C ₃₀ alkyl, C ₁ -C ₃₀ alkoxy group, C ₁ -C ₃₀ alkylthio, C ₁ -C ₃₀ alkoxyl heteroarylene, C ₆ -C ₃₀ ahreu each other C ₁ is -C ₃₀ alkyl, said C ₁ -C ₃₀ alkyl, C ₆ -C ₃₀ ahreu C ₁ -C ₃₀ alkyl is C ₁ -C ₃₀ alkyl, C ₂ -C ₃₀ alkenyl, C ₂ -C ₃₀ alkynyl, and C ₁ -C be further substituted with one or more substituents selected at _30, and alkoxy;

and n is an integer of 1 to 2000.]

Ra and Rb are alkoxyheteroaromatic alkyl in order to increase electron mobility and high charge mobility in the above formula according to an embodiment of the present invention and to have high solubility in an organic solvent, The position of R2 changed to zigzag. R 2 is preferably a C ₁ -C ₃₀ alkyl group introduced into the organic solvent so as to have excellent solubility.

The formula (1) and formula (2) according to an embodiment of the present invention may be independently selected from the following structures, but are not limited thereto.

[In the above formula, n is 1 to 2000.]

The present invention also provides a process for preparing the organic semiconductor compound represented by the above general formula (1) or (2) by reacting the following general formula (3) with the following general formula (4).

[In the above formulas (3) and (4),

Ra And Rb is independently hydrogen, C ₁ -C ₃₀ alkyl, C ₁ -C ₃₀ alkoxy group, C ₁ -C ₃₀ alkylthio, C ₁ -C ₃₀ alkoxyl heteroarylene, C ₆ -C ₃₀ ahreu C ₁ each -C ₃₀ alkyl group, a C ₁ -C ₃₀ alkyl, C ₆ -C ₃₀ ahreu C ₁ -C ₃₀ alkyl is C ₁ -C ₃₀ alkyl, C ₂ -C ₃₀ alkenyl, C ₂ -C ₃₀ alkynyl, and C ₁ may further be substituted by one or more substituents selected -C ₃₀ alkoxy, and;

X is Se, O, or NR5 and, R5 is hydrogen, C ₁ -C ₃₀ alkyl, C ₁ -C ₃₀ alkoxy group, C ₁ -C ₃₀ alkylthio, C ₁ -C ₃₀ alkoxyl heteroarylene, C ₆ ahreu -C ₃₀ C ₁ -C ₃₀ alkyl group;

Y is halogen;

and n is an integer of 1 to 2000.]

The formulas (2) and (3) according to an embodiment of the present invention may be prepared by a method commonly known to those skilled in the art.

The present invention also provides an organic electronic device comprising the organic semiconductor compound of the present invention, particularly an organic thin film transistor or an organic solar cell.

More specifically, the present invention provides an organic electronic device containing the organic semiconductor compound of the present invention in a photoactive layer.

The organic electronic device of the present invention can be any conventional organic electronic device that a person skilled in the art can recognize. Generally, an organic solar cell is a metal-organic semiconductor (a photoactive layer) / metal (MSM, MIM) structure. ITO (Indium Tin Oxide), which has a high work function and is a transparent electrode, is used as an anode, and Al or Ca having a low work function is used as a cathode.

A BHJ (Bulk Hetero Junction) structure using an organic semiconducting compound / C60 or an organic semiconductor compound / C70 composite as an organic semiconductor is used as an electron donor and an electron acceptor, respectively.

First, the organic semiconductor compound / C60 composite solution, which is a photoactive layer, is coated on the ITO layer to a thickness of about 100 nm by spin coating, inkjet printing or the like. An Al or Ca metal is vacuum deposited thereon to be used as a cathode. If necessary, an EBL (exciton blocking layer) may be inserted between the electrode and the photoactive layer to improve the lifetime of the charge. As the EBL layer, a mixture of PEDOT (poly (3,4-ethylenedioxythiophene)) and PSS (poly (styrenesulfonate)) can be used.

In general, the diffusion distance of excitons in organic donor materials is about 10-30 nm, which is much shorter than the appropriate thickness (over 100 nm) of electron donor materials for solar absorption. This is one of the fundamental reasons for limiting the efficiency of organic solar cells. However, it is difficult to solve such a problem with the conventional bi-layer structure. In addition, since the two materials forming the BL (bi-layer) structure are organic monomolecules, it is necessary to deposit them. In the case of the polymer, it is difficult to manufacture by a simple process such as spin coating. On the other hand, since the polymer BHJ structure uses a mixture of electron donor (D) and electron acceptor (A) materials, the manufacturing process is simple and the surface area of the D / A (donor / And the charge collection efficiency as an electrode is also increased.

In this respect, the organic solar cell according to the present invention is preferably a BHJ structure, and an organic semiconductor compound according to the present invention is used as an electron-donating material and at least one selected from the following electron- .

Particularly, it is more preferable that the MIM structure is repeated once more in the layered organic solar cell element manufactured by the present invention. In other words, the BJJ structure of the electron emitter and the electron acceptor is formed in the lower layer and the MIM structure is formed in the upper layer once again in the same manner as the MIM structure of the single-layer element. The production of a detailed laminated organic solar cell element is described in the Examples.

Among the above electron-accepting materials, it is more preferable to use materials such as PCBM and PCBCR, which are designed to dissolve well in an organic solvent, but the present invention is not limited thereto.

The organic semiconducting compound of the present invention is a heteroaromatic ring containing an aromatic ring and fluorine, which is introduced into an electron acceptor and exhibits a low HOMO energy level and is very advantageous for having a nano structure. In addition, in the layered organic solar cell, organic semiconductor can be used in the lower layer (1. middle band gap, 2. high open-circuit voltage and FF, 3. thermal stability) do.

Further, the organic semiconductor compound of the present invention exhibits improved performance through combination with various electron donor materials.

Further, the organic semiconductor compound of the present invention has high thermal stability and high solubility in an organic solvent.

Therefore, the organic semiconductor compound of the present invention is introduced into an electron acceptor containing fluorine and is copolymerized with various electron donors to exhibit an intermediate band gap. Therefore, the layered organic electron containing the organic semiconductor compound of the present invention can be used as a fullerene derivative And has a remarkably high efficiency.

In addition, the organic semiconductor compound of the present invention has high thermal stability and high solubility, and thus the organic electronic device including the organic semiconductor compound has excellent electrical characteristics and can be very usefully used as a substitute for P3HT in the organic electronic device, particularly in the lower layer of the layered organic solar cell .

The present invention relates to the development of new electron donor materials, and it is important as an invention corresponding to a breakthrough capable of dramatically increasing the maximum energy conversion efficiency of existing organic solar cells.

The present invention also provides a method for producing an organic semiconductor compound having high electrical properties.

FIG. 1 shows a BHJ (Bulk Hetero Junction) mode (a) and an organic solar cell structure (b) of an organic solar cell.
2 shows the thermal stability (TGA) results of the polymers 1 and 2 prepared in the examples.
3 is a UV spectrum of a solution state of Polymers 1 and 2 prepared in Examples.
4 is a UV spectrum of the film state of Polymers 1 and 2 prepared in Examples.
5 is a HOMO LUMO energy level diagram of Polymers 1 and 2 measured through cyclic voltamogram (oxidation) of Polymer 1 prepared in Example.
6 is a JV characteristic curve of the single layer organic solar cell of the polymer 1 and 2 produced in the example.
7 is a JV characteristic curve of a single layer organic solar cell for various interfacial layers of the polymers 1 and 2 prepared in the examples.
FIG. 8 shows the structure of a layered organic solar cell device, and the structure of the polymer 2 and low-band-gap polymer used in each layer.
9 is a JV characteristic curve of a layered organic solar cell device using Polymer 2.
10 is a TEM photograph of the polymers 1 and 2 prepared in Examples.
11 shows the transfer curve of the organic thin film transistor of the polymer 1 prepared in the example.
12 shows the transfer curve of the organic thin film transistor of Polymer 2 prepared in Example.

Hereinafter, the present invention will be described in detail with reference to examples. However, the following Preparation Examples and Examples are for illustrative purposes only and are not intended to limit the scope of the present invention.

Here, unless otherwise defined in the technical terms and the scientific terms used, those having ordinary skill in the art to which the present invention belongs have the same meaning as commonly understood by those skilled in the art. Repeated descriptions of the same technical constitution and operation as those of the conventional art will be omitted.

All reagents required for synthesis were purchased from Junsei, Aldrich, Alpha, and Tixia. Silicagel was purchased from Merck and Chloroform, Hexane, Methanol and Acetone for HPLC used in the purification process of the material were purchased from JT Baker . UV in the film state was measured by filtration using a 0.45 mu m syringe filter before measurement and spin coating. PCBM ([6,6] -phenyl C71-butyric acid methyl ester) was used as an acceptor material of the solar cell element. ^{The 1} H NMR spectrum was measured with a Varian Mercury Plus 300 MHz spectrometer and the ultraviolet absorption spectrum was measured with JASCO JP / V-570. Cyclic voltammetry was measured using a CH Instruments Electrochemical Analyzer to determine the HOMO level of the material. The JV curve of the solar cell was 1 Kw Solar simulator (Newport 91192). The IPCE characteristics were measured by Solar cell response / Quantum efficiency / IPCE measurement system (PV Measurements, Inc.).

[Example 1]

Preparation of 2,6-bis (trimethyltin) -4,8-bis (triisopropylsilylethynyl) -benzo [1,2-b: 4,5-b '] dithiophene

Preparation of 4,8-Bis (triisopropylsilylethynyl) -benzo [1,2-b: 4,5-b '] dithiophene (Compound 1)

After injecting 50 mL of tetrahydrofuran and triisopropylsilyl acetylene (6.7 mL, 29.9 mmol) into a 500 mL round flask, slowly inject n-butyllithium (19.3 mL, 32.7 mmol) at 0 ° C. After two hours, benzo [1,2-b: 4,5-b '] dithiophene-4,8-dione (5 g, 13.7 mmol) was dissolved in 10 mL of tetrahydrofuran and stirred at room temperature for 24 hours. After the reaction was completed, the organic layer was extracted with chloroform and brine, and the remaining water was removed with anhydrous magnesium sulfate. The solvent was evaporated, and then 120 mL of tetrahydrofuran was injected again. SnCl 2 -2H 2 O (15.3 g, 68.1 mmol) Dissolve and inject. After stirring for 24 hours, the mixture was subjected to fractional distillation through ethyl acetate, and the remaining water was removed with anhydrous magnesium sulfate. The solvent was evaporated and recrystallized from MC (methylene chloride) and methanol to obtain a yellow solid 4,8-bis (triisopropylsilylethynyl) -benzo [1,2-b: 4,5-b '] dithiophene (Compound A). (Yield: 58%).

^{1 H NMR (300 MHz, CDCl} 3, ppm): δ 7.61 (d, 2H), 7.56 (d, 2H), 1.23 (m, 42H). ¹³ C NMR (75 MHz, CDCl _3, ppm):? 140.86, 138.51, 128.28, 123.14, 112.18, 102.63, 101.62, 18.78, 11.33. Anal. Calcd for C ₃₆ H ₄₆ S ₂ Si ₂ : C, 69.75; H, 8.41; S, 11.64. Found: C, 69.71; H, 8.40; S, 11.63.

Preparation of 2,6-bis (trimethyltin) -4,8-bis (triisopropylsilylethynyl) -benzo [1,2-b: 4,5-b '] dithiophene

50 mL of tetrahydrofuran and Compound A (1.5 g, 2.7 mmol) were injected into a 500 mL round-bottomed flask, and TMEDA (1.2 mL, 8.1 mmol) and n-butyllithium (5.1 mL, 32.7 mmol) do. After 30 minutes, trimethyltinchloride (10.8 mL, 10.8 mmol) is injected and stirred at room temperature for 24 hours. After completion of the reaction, the reaction mixture was subjected to fractional distillation through ethyl acetate, and then the remaining water was removed with anhydrous magnesium sulfate. The solvent was evaporated and recrystallized from MC (methylene chloride) and methanol to obtain a yellow solid To obtain 2,6-bis (trimethyltin) -4,8-bis (triisopropylsilylethynyl) -benzo [1,2-b: 4,5-b '] dithiophene (Compound A). (Yield: 60%) ¹ H NMR (300 MHz, CDCl _3, ppm):? 7.69 (s, 2H), 1.23 (m, 42H). 0.47 (s, 18 H). ¹³ C NMR (75 MHz, CDCl _3, ppm):? 144.68, 143.51, 139.10, 110.36, 103.33, 100.64, 19.06, 11.39, -8.3. Anal. Calcd for C ₃₈ H ₆₂ S ₂ Si ₂ Sn ₂ : C, 52.06; H, 7.13; S, 7.32. Found: C, 52.09; H, 7.11; S, 7.29.

[Example 2]

Preparation of 5,8-bis (5-bromothiophen-2-yl) -6,7-difluoro-2,3-bis (4-octyloxyphenyl) quinoxaline

5,8-dibromo-6,7-difluoro-2,3-bis (4- (octyloxy) phenyl) quinoxaline (Compound 1)

4,5-difluorobenzene-1,2-diamine (1.00 g, 1.30 mmol) and 1,2-bis (4- (octyloxy) phenyl) ethane-1 , And 2-dione (1.55 g, 1.30 mmol), add 60 mL of ethanol and 20 mL of acetic acid, and stir at 80 ° C for 24 hours. After completion of the reaction, fractional distillation was carried out through MC (methylene chloride), and the remaining water was removed with anhydrous magnesium sulfate. The solvent was evaporated and recrystallized from MC (methylene chloride) and methanol to obtain 5,8-dibromo -6,7-difluoro-2,3-bis (4- (octyloxy) phenyl) quinoxaline (Compound 1). ^{(Yield: 95%) 1 H NMR (} 300 MHz, CDCl 3, ppm): δ 7.64 (d, 4H), 6.89 (d, 4H), 3.98 (t, 4H), 1.79 (m, 4H), 1.45- 1.29 (m, 20H), 0.88 (t, 6H). ¹³ C NMR (75 MHz, CDCl _3, ppm):? 160.8, 159.9, 158.5, 140.9, 130.8, 124.9, 120.7, 104.5, 70.1, 39.1, 30.4, 29.8, 27.2, 22.7, 14.1. Anal. Calcd for C ₃₆ H ₄₂ N ₂ : C, 59.03; H, 5.78; N, 3.82. Found: C, 58.88; H, 5.69; N, 4.01.

Preparation of 6,7-difluoro-2,3-bis (4- (octyloxy) phenyl) -5,8-di (thiophen-2-yl) quinoxaline

Compound (1) (1.00 g, 1.90 mmol) was injected into a 100 mL round-bottomed flask equipped with a condenser, bis (triphenylphosphine) palladium (II) dichloride (95 mg, 0.06 mmol) was dissolved in 20 mL of tetrahydrofuran, Raise the temperature to 100 degrees. Then, tributyl (thiophen-2-yl) stannane (1.19 g, 4.85 mmol) is slowly added. Stir at a temperature of 100 degrees for 12 hours. After completion of the reaction, the reaction mixture was subjected to fractional distillation through ethyl acetate, and then the remaining water was removed with anhydrous magnesium sulfate. The solvent was evaporated and recrystallized from MC (methylene chloride) and methanol to obtain 6,7-difluoro- 3-bis (4- (octyloxy) phenyl) -5,8-di (thiophen-2-yl) quinoxaline (Compound 2). ^{(Yield: 58%) 1 H NMR (} 300MHz, CDCl 3, δ): 8.03 (d, 2H), 7.70 (d, 2H), 7.63 (d, 2H), 7.23 (t, 2H), 6.91 (d, 2H), 4.01 (t, 4H), 1.80 (m, 4H), 1.46-1.29 (m, 20H), 0.88 (t, 6H). ^{13 C NMR (75 MHz, CDCl} 3, δ): 160.1, 158.7, 154.7, 150.9, 147.5, 132.6, 131.2, 130.5, 129.8, 127.6, 125.2, 119.8, 70.1, 35.6, 30.5, 29.1, 26.3, 21.9, 15.8 . Anal. Calcd for C ₄₄ H ₄₈ N ₂ S ₂ : C, 71.51; H, 6.55; N, 3.79; S, 8.68. Found: C, 70.49; H, 6.48; N, 3.99; S, 9.01.

Preparation of 5,8-bis (5-bromothiophen-2-yl) -6,7-difluoro-2,3-bis (4-octyloxyphenyl) quinoxaline

Compound 2 (1.00 g, 1.92 mmol) is added to a 250 mL round flask with 25 mL of DMF and then N - bromosuccinimide (0.60 g, 4.79 mmol) is slowly added at 0 degrees. After the reaction was completed at room temperature for 3 hours, the reaction was completed by fractional distillation through methylene chloride, and the remaining water was removed with anhydrous magnesium sulfate. The solvent was evaporated and recrystallized from MC (methylene chloride) and methanol to obtain a yellow solid , 8-bis (5-bromothiophen-2-yl) -6,7-difluoro-2,3-bis (4-octyloxyphenyl) quinoxaline (compound B). ^{(Yield: 80%) 1 H NMR (} 300MHz, CDCl 3, ppm): δ7.80 (d, 2H), 7.66 (d, 2H), 7.18 (d, 2H), 6.94 (d, 2H), 4.01 ( t, 4H), 1.83 (m, 4H), 1.48-1.29 (m, 20H), 0.89 (t, 6H). ^{13 C} NMR (75 MHz, CDCl _3, ppm): δ 161.8, 159.1, 158.4, 152.7, 150.3, 147.3, 130.1, 129.9, 129.2, 127.8, 119.5, 111.6, 70.1, 33.9, 32.2, 29.3, 26.2, . Anal. Calcd for C ₄₄ H ₄₆ N ₂ S ₂ : C, 58.93; H, 5.17; N, 3.12; S, 7.15. Found: C, 60.10; H, 5.21; N, 3.51; S, 7.20.

[Example 3]

D] [1,2,3] triazole (Compound C) was prepared from 4,7-bis (5-bromothiophen-2-yl) -5,6-difluoro-2- (heptadecan-9- Produce

Preparation of 4,7-dibromo-5,6-difluoro-2H-benzo [d] [1,2,3] triazole (Compound 1)

60 mL of acetic acid, 30 mL of distilled water and sodium nitrite (1.77 g, 25.6 mmol) were slowly added to a 250 mL round-bottomed flask equipped with a stirrer, After that, the mixture was stirred at room temperature for 20 minutes. When the reaction is completed, the resulting solid is filtered through distilled water to obtain 4,7-dibromo-5,6-difluoro-2H-benzo [d] [1,2,3] triazole (Compound 1). (Yield: 80%). Anal.Calcd for C ₆ H ₃ Br ₂ N ₃ : C, 26.02; H, 1.09; Br, 57.71; N, 15.17. Found: C, 25.91; H, 0.99; N, 15.12.

Preparation of 4,7-dibromo-5,6-difluoro-2- (heptadecan-9-yl) -2H-benzo [d] [1,2,3] triazole

(4.43 g, 16.0 mmol), heptadecan-9-ol (4.92 g, 19.2 mmol) and PPh3 (5.04 g, 19.2 mmol) were charged in a 250 mL round-bottomed flask and 50 mL of tetrahydrofuran was introduced. Diisopropyl azodicarboxylate (3.88 g, 19.2 mmol) was slowly added at 0 ° C and stirred at room temperature for 3 hours. After completion of the reaction, fractional distillation was carried out through methylene chloride, and the remaining water was removed with anhydrous magnesium sulfate. The solvent was evaporated and purified by column chromatography to obtain 4,7-dibromo-5,6 -difluoro-2- (heptadecan-9-yl) -2H-benzo [d] [1,2,3] triazole (Compound 2). (M, 2H), 1.31-1.21 (m, 22H), 1.08-0.96 (m, 2H) (m, 2 H), 0.86 (t, 6 H). 13C NMR (75 MHz, CDCl3, delta): 143.31, 129.22, 110.11, 69.54, 35.59, 31.75, 29.22, 29.14, 29.01, 26.05, 22.62, 14.16. Anal. Calcd for C23H37Br2N3: C, 53.60; H, 7.24; Br, 31.01; N, 8.15. Found: C, 53.80; H, 7.30; N, 8.10.

Preparation of 5,6-difluoro-2- (heptadecan-9-yl) -4,7-di (thiophen-2-yl) -2H-benzo [d] [1,2,3] triazole

Compound (2) (1.00 g, 1.90 mmol) was injected into a 100 mL round-bottomed flask equipped with a condenser, bis (triphenylphosphine) palladium (II) dichloride (95 mg, 0.06 mmol) was dissolved in 20 mL of tetrahydrofuran, Raise the temperature to 100 degrees. Then, tributyl (thiophen-2-yl) stannane (1.60 g, 4.85 mmol) is slowly added. Stir at a temperature of 100 degrees for 12 hours. After completion of the reaction, the reaction mixture was subjected to fractional distillation through ethyl acetate, and then the remaining water was removed with anhydrous magnesium sulfate. The solvent was evaporated and recrystallized from MC (methylene chloride) and methanol to obtain 5,6-difluoro-2- 2-yl) -2H-benzo [d] [1,2,3] triazole (Compound 3). (M, 2H), 7.20 (d, 2H), 7.23 (t, 2H), 4.90 (m, ), 2.01 (m, 2H), 1.31-1.21 (m, 22H), 1.08-0.96 (m, 2H), 0.86 (t, 6H). 13C NMR (75 MHz, CDCl3, delta): 140.2, 132.8, 130.5, 129.2, 125.0, 69.54, 35.59, 31.75, 29.22, 29.14, 29.01, 26.05, 22.62, 14.16. Anal. Calcd for C31H43N3S2: C, 71.35; H, 8.31; N, 8.05; S, 12.29. Found: C, 70.88; H, 8.25; N, 7.98; S, 12.11.

D] [1,2,3] triazole (Compound C) was prepared from 4,7-bis (5-bromothiophen-2-yl) -5,6-difluoro-2- (heptadecan-9- Produce

Compound 3 (1.00 g, 1.92 mmol) is added to a 250 mL round flask with 25 mL of DMF and N - bromosuccinimide (1.02 g, 4.79 mmol) is slowly added at 0 ° C. After the reaction was completed at room temperature for 3 hours, the reaction was completed by fractional distillation through methylene chloride, and the remaining water was removed with anhydrous magnesium sulfate. The solvent was evaporated and recrystallized from MC (methylene chloride) and methanol to obtain a yellow solid , 7-bis (5-bromothiophen-2-yl) -5,6-difluoro-2- (heptadecan-9-yl) -2H-benzo [d] [1,2,3] triazole do. (Yield: 80%). (M, 2H), 2.01 (m, 2H), 1.31-1.21 (m, 2H) m, 22H), 1.08-0.96 (m, 2H), 0.86 (t, 6H). 13 C NMR (75 MHz, CDCl 3, ppm):? 144.2, 140.5, 135.5, 133.1, 128.0, 115.6, 70.32, 38.61, 35.15, 30.28, 30.10, 29.52, 27.11, 26.32, 12.18. Anal. Calcd for C31H41Br2N3S2: C, 54.79; H, 6.08; N, 6.18; S, 9.44. Found: C, 55.01; H, 6.00; N, 5.99; S, 8.74.

[Example 4] Production of organic semiconductor compound (polymer 1)

After removing water and oxygen by vacuum treatment in a round flask equipped with a condenser, Compound A (400 mg) and Compound C (330 mg) were dissolved in anhydrous toluene (10 mL). The Pd (pph3) 4 catalyst (10 mg, 0.03 eq) was dissolved in 1 mL of anhydrous DMF and added. After completion of the reaction, the resulting solid was dissolved in chloroform, and the solid was collected by filtration to remove the catalyst. The precipitate was recrystallized in methanol to obtain a purple solid. The resulting solid was dissolved in methanol and acetone And purified by an extractor (Soxhlet) to obtain Polymer Compound 1. The prepared polymer 1 was well dissolved in chloroform, THF and toluene which are general organic solvents at room temperature. The physical properties and optical characteristics of the obtained polymer are shown in Figs. 2 to 5. Fig.

Mw: 80 000 Mn: 30 000 PDI = 2.7 T d (o C) = 397

[Example 5] Production of organic semiconductor compound (polymer 2)

The compound A (300 mg) and the prepared compound B (450 mg) were added to a round flask equipped with a condenser to remove water and oxygen, and then dissolved in anhydrous toluene (10 mL). The Pd (pph3) 4 catalyst (10 mg, 0.03 eq) was dissolved in 1 mL of anhydrous DMF and added. After completion of the reaction, the resulting solid was dissolved in chloroform, and the solid was collected by filtration to remove the catalyst. The precipitate was recrystallized in methanol to obtain a purple solid. The resulting solid was dissolved in methanol and acetone And purified with an extractor (Soxhlet) to obtain Polymer Compound 2.

Mw: 42 000 Mn: 21 000 PDI = 1.9 T d (o C) = 432

The prepared polymer was well dissolved in chloroform, THF and toluene which are common organic solvents at room temperature. The physical properties and optical characteristics of the obtained polymer are shown in Figs. 2 to 5. Fig.

The thermogravimetric analysis (TGA) curves of the polymers 1 and 2 prepared in Examples 4 and 5 are shown in FIG. 2. As shown in FIG. 2, the polymers 1 and 2, which are the organic semiconductor compounds of the present invention, .

The polymers 1 and 2 prepared in Examples 4 and 5 were dissolved in an organic solvent such as chloroform or chlorobenzene to measure a UV absorption spectrum in a solution state and a solid film state, and the results are shown in FIG. 3 and FIG.

As shown in FIG. 3, in the UV absorption spectra of the polymers 1 and 2 prepared in Examples 4 and 5, the polymer 1 was 490; Polymer 2 showed two large absorption spectra of 348, 419 and 548 nm. The first absorption spectrum is the absorption spectrum of the π-π transition and the second absorption spectrum is the internal molecule charge transfer between the electron-donating monomer and the electron accepting monomer (ICT) spectrum.

As shown in FIG. 4, in the UV absorption spectra of the films prepared in Examples 4 and 5, Polymer 1 was 518; Polymer 2 exhibited maximum absorption at 350 and 582 nm. This spectral result showed a red-shift of about 30 nm. It is presumed that the molecules are distributed over a wide range in the solution state and move comparatively freely, but in the case of the solid film state, the aggregation tendency phenomenon of the respective groups. As a result, bandgap of polymer 1 and polymer 1 was 1.90 and band gap of 1.85 eV, respectively (Bandgap = 1240 / λ _edge ) using the absorption spectrum in the film state.

The HOMO level of the material was also determined by cyclic voltammetry as shown in Fig. Ferrocene / Ferrocenium redox system (-4.8V) was measured in the state of a solid film and the HOMO level was calculated as -5.48 and -5.62 eV for Polymers 1 and 2, respectively. The band gap The LUMO energy levels of the respective polymers were calculated to be -3.66 and -3.75 eV, respectively.

The measured J-V characteristic curves of the single layer organic solar cell device using the polymers 1 and 2 synthesized in this study are shown in FIG. Polymer 1 and Polymer 2 showed low photoelectric conversion efficiencies of 0.81 and 1.87%, respectively. In this study, photoelectric conversion efficiency was expected to be improved by using an additive such as 1,8-diiodooctane (DIO) in order to obtain more improved photoelectric conversion efficiency. In the case of polymer 1, 0.93% , And polymer 2 showed an improved photoelectric conversion efficiency of 4.55%.

In this study, the effect of Ca and poly (9,9'-bis (3 '- (N, N-dimethyl) -propyl-2,7-fluorene) -alt- 7 (9,9 ') dioctylfluorene) (PFN) was formed between the photoactive layer and the Al electrode by vapor deposition or solution process. Polymer 1 exhibited an improved photoelectric conversion efficiency of 1.59% in the Ca / Al device and 1.60% in the PFN / Al device. Polymer 2 exhibited a high FF value in the Ca / Al device and 5.12% in the PFN / % Of photoelectric conversion efficiency.

Therefore, in order to fabricate a high efficiency inversion layer organic solar cell device, we fabricated the device by selecting the middle band gap polymer 2 which showed high efficiency in general device.

[Example 6] Fabrication of organic solar cell device

In order to investigate the photovoltaic characteristics of a layered organic solar cell device fabricated by using the polymers 1 and 2 prepared in Examples 4 and 5 as a new electron donor material [ITO / PEIE / organic semiconductor compound (polymer 1) : Organic semiconductor compound of PCBM (C71) / PEDOT: PSS / low bandgap: PCBM (C71) / MoO3 / Ag] structure was fabricated. The PEIE introduced in the present invention is a previously reported interfacial layer and has a structure as shown in FIG. 8 for a low bandgap organic semiconductor compound (PBPT-8).

First, UV-O ₃ is treated on a clean ITO (Indium Tin Oxide) glass, and then PEI (ethoxylated polyethlyenimine) is spin-coated at 500 rpm for 1 minute and then heat-treated at 120 degrees for 10 minutes. The thickness of the PEIE is 10 nm. Each of the polymers 1 and 2 and PCBM (C70) were added to dichlorobenzene at a weight ratio of 1: 1, and the mixture was stirred at 50 ° C for 24 hours for sufficient mixing of the two materials to prepare an organic semiconductor compound mixture. The organic semiconductor compound mixture solution was spin-coated on the EBL layer as a coating layer under nitrogen, followed by heat treatment at 120 ° C for 10 minutes to form a photoactive layer having a thickness of 100 nm. PEDOT: Spin coat PSS. Once the PEDOT: PSS is spin coated, the PEIE is coated again under the same conditions as above, and the low-bandgap organic semiconductor compound PBDT-8: PCBM (C70) is spin-coated at 1000 rpm for 20 seconds. (About 80 nm thick) and finally deposited at a high temperature with MoO 3 (10 nm) / Ag (100 nm). In order to investigate the photovoltaic characteristics of the fabricated organic solar cell device, a solar simulator and a radiant power meter were used to generate 100 mW photovoltaic cells under AM 1.5 conditions, and a 1 kW solar simulator (Newport 91192) The current density-voltage characteristics of the organic solar cell were measured using the photolithography method and the results are shown in FIG.

First, inversion monolayer type organic solar cell devices were fabricated before fabricating the inverted laminated solar cell. As can be seen in Figure X, all devices showed a high open-circuit voltage compared to the short-circuit current, which can be expected to be the result of the characterization of Polymer 1 and Polymer 2 exhibiting low HOMO energy levels.

As shown in FIG. 9, the polymer 2 exhibits a high FF of 10.64 mA / cm ² and 0.63, which is obtained by forming a superior nano structure due to the presence of fluorine, and has a high electron and hole mobility It can be said that it is a factor indicating the short-circuit current value.

The electrical characteristics of the organic solar cell device prepared in Example 6, which contains the polymer 1 and the polymer 2, which are the organic semiconductor compounds prepared in Example 4 and Example 5, as the photoactive layer, and the electrical characteristics of the inversion stack organic solar cell device Are also shown in Table 1 below. That is, the photovoltaic parameters of V _oc (open circuit voltage), short-circuit current density (J _SC ), fill factor (FF), and overall conversion efficiency (η) Respectively.

(a) Characteristics of Organic Solar Cells of Spin-coated Polymer / PCBM (C70) in chloroform (3 Vol% diiodooctane) b. ITO / PEIE / Polymer 1: PC ₇₁ BM / PEDOT: PSS / PEIE / PBPT-8: Reverse polarity laminated organic solar cell structure of PC ₇₁ BM / MoO ₃ / Ag)

As shown in Table 1, the lower layer materials not reported so far can exhibit excellent characteristics of 7.40% using the novel organic semiconductor compounds. In general, the P3HT used in the inversion layer organic solar cell has a very high HOMO energy level and has a disadvantage of exhibiting a low open-circuit voltage. However, the polymer 2 developed in the present invention contains fluorine and exhibits a very low HOMO energy level, which is a decisive cause of high open-circuit voltage. In addition, polymer 2 has excellent nano structure as shown in the TEM image of FIG. 10, and the nano structure of such polymer is advantageous for realizing high FF because it has excellent BHJ state with PCBM.

The inversion layer organic solar cell using polymer 2 as the photoactive layer of the organic semiconductor compound of the present invention is reported for the first time in the world and it is expected that the maximum efficiency in the fabrication of the P3HT alone inversion layer stack organic solar cell can be surpassed to date.

[Example 7] Fabrication of organic thin film transistor (OTFT) device

The devices 1 and 2 synthesized in Examples 4 and 5 were used as a p-type active layer polymer. In order to measure the electric field mobility of the charge transporting body, an organic thin film transistor (OTFT) was fabricated by bottom electrode geometry (channel length L = 12

m, width W = 120

m) under nitrogen. A 300 nm n-doped silicon wafer was used as a substrate / gate electrode with a thermally grown SiO ₂ dielectric film (200 nm). The semiconductor active layer was spin-coated with 0.5 wt% chlorobenzene solution. Next, a pair of gold source / drain electrodes was thermally deposited to a thickness of 50 nm by vacuum evaporation (at ~ 10 ^-7 torr) through a shadow mask. The channel length was 12 μm and the width was 120 μm. TFT devices showed typical p -channel transistor characteristics.

The electric field mobility was calculated from the saturation regime using the following equation. That is, a graph was obtained from the saturation region current equation (I _ds ) ^1/2 and V _gs as variables and the slope was obtained.

I _ds = (W / 2L)

C _i (V _gs -V _th ) ²

In this formula,

I _ds is the drain-source current in the saturation region;

W and L are the channel width and length, respectively;

The electric field mobility;

C _i is the capacitance per unit area of the insulating layer;

V _gs and V _th represent gate and bottom voltages, respectively.

11 and 12 show the transfer curves of the polymers 1 and 2 of the present invention.

As shown in FIGS. 11 and 12, polymer 1 exhibited very good mobility of 10 ^-3 cm ² / Vs, which is a decisive factor for high short-circuit current in organic solar cells.

Claims (6)

delete delete delete Is selected from the following formulas.

[In the above formula, n is 1 to 2000.] An organic electronic device comprising the organic semiconductor compound according to claim 4. A layered organic solar cell device using the organic semiconductor compound according to claim 4 as an electron donor layer in a lower layer.

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