KR101184342B1 - A polymer for organic solar-cell and preparation method thereof - Google Patents

Abstract

The present invention provides a novel semiconductor polymer by copolymerizing thieno [3,4-b] thiophene derivative and carbazole derivative, which is used to manufacture high efficiency solar cell through effective absorption of sunlight, and organic solar cell Its use in

Description

A polymer for organic solar cell and preparation method thereof

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor polymer for an organic solar cell and a method of manufacturing the same. More specifically, a thieno [3,4-b] thiophene derivative having a small band gap and a capa Provided are a polymer for an organic solar cell and a method of manufacturing the same, which can produce a high efficiency solar cell through the effective absorption of sunlight by copolymerizing a sol derivative.

Organic solar cells are attracting attention as next-generation solar cells that can replace the well-known silicon solar cells because they can be manufactured at a low cost and large-area thin film.

However, organic solar cells have a disadvantage in that commercialization is difficult due to lower energy conversion efficiency than conventional silicon solar cells. In the case of poly (3-hexylthiophene), which is a representative polymer showing the best light conversion efficiency at present, the absorption of sunlight does not exceed around 650 nm, so the loss of sunlight is large and thus the light conversion efficiency is limited. In order to reduce the loss of solar light, it is essential to manufacture a polymer having a small band gap and to develop a solar cell using the same. Representative examples are polymers published by Luping Yu and Christoph Brabec of the United States.

However, the polymers also have a disadvantage in that the absorption of sunlight does not exceed 900 nm and the solubility of the polymer main chain is reduced due to the large rigidity of the polymer main chain, thereby increasing the number and length of alkyl groups bonded to the main chain. have.

Generally, thieno-thiophene derivatives not only stabilize the quinoidal structure in the polymer main chain, but also increase the planarity of the aromatic polymer main chain. This results in better conjugation between the units, resulting in a relatively small bandgap. The quinone type structure is used as a chromophore having a specific paired double bond, and most of the organic pigments may include these structures. However, poly (thieno [3,4-b] thiophene), poly (2-hexyl-thieno [3,4-b] thiophene), poly (2-phenyl-thieno [3,4-b] Thiophene) has a disadvantage in that the chemical stability of the polymers (polymer chemistry) is greatly reduced and the application is limited.

In order to solve the problems of the prior art as described above, an object of the present invention is to provide a polymer for an organic solar cell having a small bandgap (low bandgap) that can absorb sunlight in the long wavelength band.

Another object of the present invention is to provide a polymer suitable for a roll-to-roll process with a long lifespan by overcoming the low chemical stability and solubility of conventional polymers for organic solar cells.

The present invention provides a carbazole-based polymer compound for an organic solar cell represented by the following formula (1).

[Formula 1]

In the above formula, R ₁ and R ₂ are each independently a linear or branched alkyl group having 1 to 10 carbon atoms, and n is an integer of 15 to 70.

Also,

(a) a thieno [3,4-b] thiophene compound of formula (2), and

(b) preparing a compound of formula 1 by copolymerizing a carbazole compound of formula 3

It provides a method for producing a carbazole-based polymer compound for an organic solar cell comprising a.

[Formula 1]

[Formula 2]

(3)

Wherein X is each independently a halogen element, R ₁ and R ₂ are each a linear or branched alkyl group having 1 to 10 carbon atoms, and R ₃ is each -C (R ₅ ) ₂ -C (R ₅ ) ₂ Or a divalent organic group of C (R ₅ ) ₂ -CH ₂ -C (R ₅ ) _2- , wherein R ₅ is a straight or branched chain alkyl group having 1 to 10 carbon atoms, n is 15 It is an integer of -70.

In addition, the present invention is a transparent substrate,

A lower electrode formed on the transparent substrate,

A buffer layer formed on the lower electrode,

A photoactive layer formed on the buffer layer and comprising the carbazole polymer compound;

An upper electrode formed on the photoactive layer

It provides an organic solar cell comprising a.

Hereinafter, the present invention will be described in detail.

The present invention relates to a polymer for an organic solar cell using a derivative compound in which an ester group is bound to a thieno [3,4-b] thiophene compound, and a carbazole compound, and a manufacturing method thereof.

A derivative compound (hereinafter, thieno [3,4-b] thiophene compound) having an ester group bonded to the thieno [3,4-b] thiophene-based compound may improve chemical stability of the copolymerized polymer. That is, the thieno-thiophene compound itself is inferior in chemical stability, but in the case of the present invention, by using the ester derivative as a substituent, the chemical stability of the polymer can be greatly improved. In addition, the coupling of the ester group promotes the improvement of the solubility, which is another object of the present invention, and can produce a polymer having excellent solubility only by the bonding of a relatively short length alkyl group. In addition, the carbazole compound according to the present invention increases rigidity and planarity of the polymer main chain and increases chemical stability, which is a weak point of thieno-thiophene derivatives due to large aromatic properties such as florine derivatives.

Therefore, the polymer combined with the two compounds as a monomer has excellent solar absorption capacity and chemical stability in a wide range of areas.

Such an organic solar cell polymer of the present invention may be a structure represented by the following formula (1).

[Formula 1]

In the above formula, R ₁ and R ₂ are each independently a linear or branched alkyl group having 1 to 10 carbon atoms, and n is an integer of 15 to 70.

In addition, in Formula 1, R ₁ and R ₂ are each independently an ethylhexyl group. In addition, n in Formula 1 is more preferably 20 to 50. Preferably, the carbazole-based polymer compound of Formula 1 may have a weight average molecular weight of 20000 to 40000.

In addition, since the carbazole-based polymer compound of Formula 1 has an absorption spectrum of 500 nm to 1100 nm, it can be used in devices such as organic solar cells to minimize the loss of sunlight to greatly improve the light conversion efficiency.

On the other hand, the method for producing a carbazole polymer compound of the present invention

(a) a thieno [3,4-b] thiophene compound of formula (2), and

(b) preparing a compound of Formula 1 by copolymerizing a carbazole compound of Formula 3;

[Formula 1]

[Formula 2]

(3)

Wherein X is each independently a halogen element, R ₁ and R ₂ are each a linear or branched alkyl group having 1 to 10 carbon atoms, and R ₃ is each -C (R ₅ ) ₂ -C (R ₅ ) ₂ Or a divalent organic group of C (R ₅ ) ₂ -CH ₂ -C (R ₅ ) _2- , wherein R ₅ is a straight or branched chain alkyl group having 1 to 10 carbon atoms, n is 15 It is an integer of -70.

Next, a method for preparing a carbazole polymer compound according to a preferred embodiment of the present invention will be described in detail with reference to Schemes 1 to 4.

Scheme 1 below shows a process for preparing a carbazole compound of Formula 1 by the reaction of Formulas 2 and 3 mentioned above.

[Reaction Scheme 1]

As shown in Scheme 1, the copolymerization reaction for preparing the polymer preferably consists of a reaction based on a Suzuki coupling reaction under a base and a palladium catalyst. In addition, the copolymerization reaction may be performed for 24 to 72 hours at a temperature of 80 ℃ to 120 ℃.

In this case, the Suzuki coupling reaction refers to a synthesis method in which a boronic acid derivative compound such as arylboronic acid and an aromatic halogenated compound are reacted under a base and a palladium catalyst to form a C-C bond therebetween.

In addition, the compound of Formula 3 should be used in a precise ratio of 1: 1 with respect to the compound of Formula 2.

The base may be sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate or the like, and the kind thereof is not particularly limited. In addition, the palladium catalyst may be tetrakistriphenylphosphine, palladium acetate and the like, but the kind is not limited and can be used a conventional well-known material.

The reaction organic solvent may be THF, DMF, toluene, dimethylchloromethane, DMSO and the like.

In addition, the reaction can proceed under normal or high pressure and inert atmosphere, the conditions are preferably a high pressure inert atmosphere. Nitrogen, argon, helium, etc. can be used for the said inert atmosphere.

In addition, the thieno [3,4-b] thiophene compound of Formula 2 and the carbazole compound of Formula 3 may be obtained by the following Schemes 2 to 4.

Scheme 2

Scheme 3

Scheme 4

First, referring to Scheme 2, the thieno [3,4-b] thiophene compound represented by the following Chemical Formula 2 may be thieno [3,4-b] thiophene-2-carboxylic acid and halosuccinic acid represented by the following Chemical Formula 4. The carboxylic acid compound of formula 5 may be prepared by halogenation of an imide, and the carboxylic acid compound of formula 5 and the alcohol of formula 6 may be prepared under an acid catalyst.

[Formula 4]

[Chemical Formula 5]

[Formula 6]

R ₁ -OH

In the above formula, each X is independently a halogen element, and R ₁ is a linear or branched alkyl group having 1 to 10 carbon atoms.

At this time, the thieno [3,4-b] thiophene-2-carboxylic acid used to prepare the compound of Formula 2 is 4,6-dihydrothieno [3,4-b] thiophene-2-carboxylic acid. 5-oxide (e) can be prepared by reaction with acetic anhydride and a base. In addition, as in Scheme 2, the 6-dihydrothieno [3,4-b] thiophene-2-carboxylic acid 5-oxide (e) is based on a thiophene carbonyl halide such as thiophene carbonyl chloride as a starting material. A thiophene carboxylate compound of formula (a) is prepared and chloromethyl methyl ether is reacted to prepare a compound of formula (b), followed by a cyclization reaction to prepare an ester compound of formula (c). Subsequently, the ester compound is hydrolyzed under basic conditions to prepare a carboxylic acid compound of formula d, followed by an oxidation reaction to prepare a compound of formula e using an oxidizing agent such as MCPBA.

In addition, referring to the schemes 3 and 4, the carbazole compound of formula 3 is prepared by the nitration reaction of 4,4-dihalophenyl to prepare a compound of formula (7), reduction of the compound of formula (7) To prepare a compound of Formula 8, the carbazole compound of Formula 8 and the alkyltosylate of Formula 10 prepared by the tosylation of Formula 9 to prepare a compound of Formula 11, the compound of Formula 11 and Formula 12 It can be prepared by reacting a compound of.

[Formula 7]

[Formula 8]

[Chemical Formula 9]

R ₂ -OH

[Formula 10]

R ₂ -OTs

[Formula 11]

[Chemical Formula 12]

Wherein each X is independently a halogen element, R ₂ is a linear or branched alkyl group having 1 to 10 carbon atoms, and R ₃ is each -C (R ₅ ) ₂ -C (R ₅ ) ₂ -or -C (R ₅ ) is a _divalent organic group of ₂ -CH ₂ -C (R ₅ ) _2- (wherein R ₅ is a straight or branched chain alkyl group having 1 to 10 carbon atoms), R ₄ is hydrogen or 1 carbon To 10 straight or branched chain alkyl groups.

It is preferable that the compound of Formula 12 is a compound of Formula 12-1 or Formula 12-2.

[Formula 12-1]

[Formula 12-2]

In the above formula, R ₄ is hydrogen or a linear or branched alkyl group having 1 to 10 carbon atoms.

At this time, the conditions are not particularly limited in each reaction step according to Schemes 2 to 4 for preparing the general formula (2) and the general formula (3), it can be carried out according to the conditions such as general oxidation reaction, hydrolysis reaction, reduction reaction. In addition, the solvent used in the present invention may use a material well known to those skilled in the art. For example, the organic solvent may be the above-mentioned THF, DMF, toluene, dimethylchloromethane, DMSO and the like. Moreover, alcohol solvents, such as methanol and ethanol, can be used according to reaction conditions.

On the other hand, the present invention can provide an organic solar cell using a carbazole-based high molecular compound of the formula (1).

Preferably, the present invention, as shown in Figure 2, the transparent substrate 1, the lower electrode (2) formed on the transparent substrate, the buffer layer (3) formed on the lower electrode, formed on the buffer layer of the formula (1) It is possible to provide an organic solar cell including a photoactive layer 4 including a carbazole polymer compound, and an upper electrode 5 formed on the photoactive layer.

The transparent substrate may be a plastic substrate, glass substrate, quartz substrate selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, aromatic polyester and polyimide.

The lower electrode may be indium tin oxide (ITO), fluorine tin oxide (FTO), antimony tin oxide (ATO, SnO ₂ -Sb ₂ O ₃ ), gallium tin oxide (GTO), ZnO-Ga ₂ O ₃ or ZnO -Al ₂ O ₃ may be.

The buffer layer may include at least one conductive material selected from the group consisting of PEDOT: PSS, polyaniline, polypyrrole, conductive metal, CuO, NiO, molybdenum oxide (MoO ₃ ), and tungsten oxide (WO ₃ ).

The upper electrode may include a conductive metal such as aluminum, gold, silver, a metal alloy thereof, a metal oxide, or a conductive polymer.

Copolymers of thieno [3,4-b] thiophene derivative compounds and carbazole derivative compounds according to the present invention have excellent solubility, chemical stability, and ability to absorb sunlight. It has the advantage of being easy. Therefore, the carbazole-based high molecular compound of the present invention is excellent in the effect of absorbing sunlight to convert into electrical energy.

1 is a UV-visible spectrum in the THF solution of the polymer prepared in Example 15 of the present invention.
2 illustrates an example of a structure of a stacked organic solar cell using a carbazole-based polymer compound of Chemical Formula 1 according to the present invention.

Hereinafter, the Example about this invention is described. However, the following examples are merely illustrated to aid the understanding of the present invention, and the scope of the present invention is not limited to these examples.

Example  One. methyl  Thiophene-2-carboxylate ( methyl  Thiophene-2-carboxylate ( methyl thiophene -2- carboxylate )) Preparation of (a)

Add thiophene-2-carbonyl chloride (30 g, 204.6 mmol) and methanol (200 mL) to a 500 mL flask with a magnetic stir bar (magnetic stir bar) and sodium methoxide (11.1 g, 204.6 mmol) at 0 ° C. ) Was added slowly. After the addition of sodium methoxide was completed, the reaction was performed at room temperature for 2 hours. After the reaction was completed, the reaction solution was filtered and the solvent was removed by a rotary evaporator under reduced pressure. The crude product obtained was separated by column chromatography using dichloromethane as a developing solvent, to obtain methyl thiophene-2-carboxylate in a yield of 95%.

¹ H-NMR (CDCl ₃ , δ ppm): 3.84 (s, 3H, CH ₃ ), 7.28, 7.41, 7.65 (s, 1H, aromatic proton)

Example  2. methyl  4,5- Bis (chloromethyl) thiophene 2-carboxylate ( methyl  Preparation of 4,5-bis (chloromethyl) thiophene-2-carboxylate) (b)

A cooling tower and dropping funnel were installed in a 500 mL flask with a magnetic stir bar, and zinc chloride (9.60 g, 70.42 mmol) and 20.0 mL of chloromethyl methyl ether were heated to 60 ° C. in an argon atmosphere for 1 hour. Stirred. Methyl thiophene-2-carboxylate (10.0 g, 70.42 mmol) synthesized in Example 1 and 6.7 mL of chloromethyl methyl ether were added to a dropping funnel, and then slowly dropped into a flask. When the color of the reaction solution turned completely black, the reaction temperature was raised to 70 ℃ and refluxed for 6 hours. The reaction solution was cooled to room temperature and poured into ice water. The precipitate thus produced was filtered and then recrystallized in petroleum ether to obtain methyl 4,5-bis (chloromethyl) thiophene-2-carboxylate in a yield of 78.6%.

¹ H-NMR (CDCl ₃ , δ ppm): 3.89 (s, 3H, CH ₃ ), 4.59, 4.79 (s, 2H, CH ₂ Cl), 7.72 (s, 1H, aromatic proton)

Example  3. methyl  4,6- Dihydrothieno [3,4-b] thiophene 2-carboxylate ( methyl  4,6- dihydrothieno [3,4-b] thiophene-2- carboxylate ) Preparation of (c)

Methyl 4,5-bis (chloromethyl) thiophene-2-carboxylate (9.8 g, 40.98 mmol), sodium sulfite synthesized in Example 2 by installing a cooling tower in a 500 mL flask with a magnetic stir bar (3.52 g, 45.08 mmol) and 300 mL of methanol were added, and the mixture was heated to 80 ° C. and refluxed for 3 hours. After cooling to room temperature and filtering the white solid, the solvent of the remaining reaction solution was removed by rotary evaporator under reduced pressure. The crude product thus obtained was reprecipitated in water and dried in a vacuum oven for at least 12 hours to obtain methyl 4,6-dihydrothieno [3,4-b] thiophene-2-carboxylate in a yield of 33.1%.

¹ H-NMR (CDCl ₃ , δ ppm): 3.87 (s, 3H, CH ₃ ), 4.05, 4.19 (t, 2H, -CH ₂ S-), 7.48 (s, 1H, aromatic proton)

Example  4. 4,6- Dihydrothieno [3,4-b] thiophene 2-carboxylic acid (4,6-dihydrothieno [3,4-b] thiophene-2-carboxylic acid ) Preparation of (d)

To a 250 mL flask with a magnetic stir bar, methyl 4,6-dihydrothieno [3,4-b] thiophene-2-carboxylate (2.26 g, 11.28 mmol) synthesized in Example 3 was added and stirred. I was. At this time, KOH (0.95 g, 16.93 mmol) was dissolved in 5 mL of water, added to the flask, and heated to 60 ° C., followed by reaction for 16 hours. After cooling to room temperature, 5% HCl was dropped to obtain a yellow precipitate. The precipitate was filtered off, washed several times with water and dried in a vacuum oven for at least 10 hours to obtain 4,6-dihydrothieno [3,4-b] thiophene-2-carboxylic acid in 80% yield.

¹ H-NMR (CDCl ₃ , δ ppm): 4.05, 4.19 (t, 2H, -CH ₂ S-), 7.56 (s, 1H, aromatic proton), 13.34 (s, 1H, -COOH)

Example  5. 4,6- Dihydrothieno [3,4-b] thiophene -2- Carboxylic acid  5- Oxide  (4,6-Dihydrothieno [3,4-b1thiophene-2-carboxylic acid  5- oxide (e) Preparation

In a 250 mL flask with a magnetic stir bar, 4,6-dihydrothieno [3,4-b] thiophene-2-carboxylic acid (0.932 g, 5.01 mmol) synthesized in Example 4 and 50 mL of chloroform were added thereto. (ice-bath) was used to stir at 0 ° C. At this time, 3-chloroperbenzoic acid (77%) (1.12 g, 5.01 mmol) dissolved in 50 mL of dichloromethane was slowly added, followed by stirring for 30 minutes. After stirring for 12 hours at room temperature, the mixture was filtered to remove the white solid. The solvent was removed from the reaction solution filtered using a rotary evaporator under reduced pressure and recrystallized from methanol to give 4,6-dihydrothieno [3,4-b] thiophene-2-carboxylic acid 5-oxide in a yield of 58%. Got it.

¹ H-NMR (CDCl ₃ , δ ppm: 3.76, 3.98, 4.33, 4.51 (d, 1H, -CH ₂ S-), 7.62 (s, 1H, aromatic proton), 13.34 (s, 1H, -COOH)

Example  6. Thieno [3,4-b] thiophene 2-carboxylic acid ( thieno [3,4-b] thiophene-2-carboxylic acid ) Preparation of (f)

To a 250 mL flask with magnetic stir bar, add 4,6-dihydrothieno [3,4-b] thiophene-2-carboxylic acid 5-oxide (1.12 g, 5.5 mmol) and 50 mL of acetic anhydride. It heated up to 120 degreeC and refluxed for 2 hours. After cooling to room temperature, the solvent was removed by a rotary evaporator. The residue was dissolved in 10 mL of THF, transferred to a 100 mL flask, and stirred at 0 ° C. using an ice bath. NaOH (0.50 g, 12.5 mmol) dissolved in 10 mL of water was added and the ice bath was removed and stirred for 12 hours. THF was removed with a rotary evaporator under reduced pressure and dripped with 0.5 M HCl to give a brown solid. The solid was then filtered and extracted with water and ethyl acetate. Water was removed from the extracted solution using MgSO ₄ , filtered and ethyl acetate was removed by rotary evaporator under reduced pressure to yield a yellow solid (thieno [3,4-b] thiophene-2-carboxylic acid) with a yield of 54%. Got it.

¹ H-NMR (CDCl ₃ , δ ppm): 7.69 (s, 1H, aromatic proton), 7.70, 7.95 (d, 2H, aromatic protons) 13.37 (s, 1H, -COOH)

Example  7. 4,6- Dibromothieno [3,4-b] thiophene 2-carboxylic acid (4,6-dibromothieno [3,4-b] thiophene-2-carboxylic acid Manufacture of 5

Into a 250 mL flask with a magnetic stir bar was added thieno [3,4-b] thiophene-2-carboxylic acid (0.69 g, 3.745 mmol) and 7 mL of DMF. N-bromosuccinimide (4) (NBS, 1.467 g, 8.24 mmol) dissolved in 5 mL of DMF under argon atmosphere and light was added. And the reaction was maintained for 24 hours, maintaining 40 degreeC. After cooling to room temperature, it was poured into a saturated aqueous solution of sodium bisulfite to give a brown precipitate, which was filtered and extracted with water and ethyl acetate. Water was removed from the extracted solution using MgSO ₄ , filtered, and ethyl acetate was removed using a rotary evaporator under reduced pressure to obtain an orange solid (4,6-dibromothieno [3,4-b] thiophene-2-). Carboxylic acid) was obtained in a yield of 39%.

¹ H-NMR (D ₆ -DMSO, δ ppm): 7.52 (s, 1H, aromatic proton), 13.46 (s, 1H, -COOH)

Example  8. (2- Ethylhexyl ) -4,6- Dibromothieno [3,4-b] thiophene -2- Carboxylate  Preparation of ((2-ethylhexyl) -4,6-dibromothieno [3,4-b] thiophene-2-carboxylate) (2)

In a 100 mL flask with magnetic stir bar 4,6-dibromothieno [3,4-b] thiophene-2-carboxylic acid (5) (0.51 g, 1.5 mmol), DCC (0.375 g, 1.8 mmol), 4- (dimethylamino) pyridine (DMAP, 63.9 mg, 0.525 mmol) and 10 mL of dichloromethane were added thereto, followed by stirring in an argon atmosphere. When all of the 4,6-dibromothieno [3,4-b] thiophene-2-carboxylic acid is dissolved, 2-ethylhexanol (6) (1.17 mL, 7.5 mmol) is added and the reaction is carried out for 24 hours. Proceeded. The reaction solution was extracted with water and ethyl acetate, and then water was removed from the extracted solution using MgSO ₄ and filtered. Under reduced pressure, ethyl acetate was removed from the filtrate with a rotary evaporator and separated by column chromatography (developing solvent: dichloromethane / hexane (1: 4)) in a yield of 58% (2-ethylhexyl) -4,6-dibro. Mothieno [3,4-b] thiophene-2-carboxylate was obtained.

¹ H-NMR (D ₆ -DMSO, δ ppm): 0.87-0.92 (t, 6H, -CH3), 1.31-1.38 (m, 8H, -CH2-), 1.70-1.80 (m, 1H, -CH) , 4.23 (d, 2H, -OCH2-) 7.52 (s, 1H, aromatic proton)

Example  9. 4,4'- dibromo -2- nitrobiphenyl  Manufacture of 7

Place a cooling tower in a 1000 mL flask with a magnetic stir bar, add 4,4'-dibromobiphenyl (20 g, 64.0 mmol) and glacial acetic acid (300 mL) at 100 ° C. Stirring was performed while heating up. When the temperature reached 100 ° C., fuming HNO ₃ (100%, 92.5 mL) and 7.5 mL of water were added slowly. The reaction solution turns red as fuming HNO ₃ is added. The reaction proceeded for 30 minutes and cooled to room temperature to precipitate a yellow solid. The precipitate was filtered off, washed with water, separated and recrystallized from ethanol to give 4,4'-dibromo-2-nitrobiphenyl in 85% yield.

¹ H-NMR (CDCl ₃ , δ ppm): 7.14-7.16 (d, 2H, aromatic protons), 7.27-7.30 (d, 1H, aromatic protons), 7.55-7.58 (d, 2H, aromatic protons), 7.74- 7.77 (dd, 1H, aromatic proton), 8.03 (d, 1H aromatic proton)

Example  10. 2,7- Dibromocarbazole (2,7- dibromocarbazole Manufacture of 8

To a 500 mL flask with a magnetic stir bar, 4,4'-dibromo-2-nitrobiphenyl (20.1 g, 56.3 mmol) and triethylphosphite (200 mL) synthesized in Example 9 were added. It was refluxed at 17 ° C. for 17 hours. As the temperature increases, the color of the reaction solution turns red when all 4,4'-dibromo-2-nitrobiphenyl is dissolved. After the reaction was cooled to room temperature, the solvent was removed using a rotary evaporator and separated by column chromatography (developing solvent: ethyl acetate / hexane (1:10)) to give 2,7-dibromocarbazole in a yield of 45.7%. .

¹ H-NMR (CDCl ₃ , δ ppm): 7.65 (d, 2H, aromatic protons), 7.88 (s, 1H, aromatic protons), 8.02 (s, 1H, aromatic protons), 8.12 (d, 2H, aromatic protons ), 10.57 (s, 1H, -NH)

Example  11. (2- Ethylhexyl ) Tosylate  ((2- ethylhexyl ) tosylate Manufacture of 10

2-ethylhexanol (9) (6.096 mL, 38.99 mmol), triethylamine (13.55 mL, 97.25 mmol), Me ₃ N.HCl (3.718 g, 38.99 mmol) and dichloromethane in 250 mL flasks with magnetic stir bar 70 mL was added and stirred in an ice bath. Tosyl chloride (11.13 g, 48.49 mmol) was dissolved in 10 mL of dichloromethane and added. The mixture was stirred for 1 hour, and then the ice bath was removed. The reaction was further performed at room temperature for 1 hour. The reaction was terminated by pouring water and extracted with water and dichloromethane. In the extracted dichloromethane solution to remove excess water using Na ₂ SO ₄ and filtered to collect only dichloromethane solution. The solvent was removed from the obtained solution by a rotary evaporator and separated by column chromatography (developing solvent: ethyl acetate / hexane (1:10)) to obtain (2-ethylhexyl) tosylate in liquid form in 76% yield.

¹ H-NMR (CDCl ₃ , δ ppm): 0.73-1.57 (m, 17 H, -CH-, -CH ₂ , -CH ₃ ), 2.45 (s, 3H, -CH ₃ on aromatic ring), 3.91- 3.93 (d, 2H, -OCH ₂ ), 7.32-7.35 (d, 2H, aromatic protons) 7.77-7.80 (d, 2H, aromatic protons)

Example  12.2,7- Dibromo -N- (2- Ethylhexyl ) Carbazole  (2,7- dibromo Preparation of -N- (2-ethylhexyl) carbazole) 11

Install dropping funnel in 250 mL flask with magnetic stir bar, add 2,7-dibromocarbazole (8) (1.25 g, 3.85 mmol), KOH (1.08 g, 19.25 mmol) and DMSO (25 mL) I was. When 2,7-dibromocarbazole was completely dissolved, (2-ethylhexyl) tosylate (10) (1.64 g, 5.77 mmol) and DMSO (5 mL) synthesized in Example 10 were dropped into a dropping funnel. I was. After the reaction was performed for 6 hours, the reaction was completed by pouring water, followed by extraction with water and hexane. In the extracted hexane solution, excess water was removed using Na ₂ SO ₄ and filtered to collect only the hexane solution. Thereafter, the solvent was removed from the hexane solution using a rotary evaporator, and separated by column chromatography (developing solvent: ethyl acetate / hexane (1:10)) to give 2,7-dibromo-N as a white solid in a yield of 76%. -(2-ethylhexyl) carbazole was obtained.

¹ H-NMR (CDCl ₃ , δ ppm): 0.87-1.36 (m, 14H, -CH ₂ , -CH ₃ ), 2.02 (m, 1H, -CH-), 4.05-4.08 (d, 2H, NCH ₂ -), 7.32-7.35 (d, 2H, aromatic protons), 7.50 (s, 2H, aromatic protons), 7.87-7.90 (d, 2H, aromatic protons)

Example  13. 2,7- Vis (4,4,5,5- Tetramethyl -1,3,2- Dioxaboloran 2-yl) -N- (2-ethylhexyl) Carbazole (2,7- Bis (4,4,5,5- tetramethyl -1,3,2- dioxaborolan -2- yl Preparation of) -N- (2-ethylhexyl) carbazole) (3)

To a flame-dried 250 mL flask with a magnetic stir bar, 2,7-dibromo-N- (2- ethhexyl) carbazole (10) (4.82 g, 11.02 mmol) and purified THF (30 mL) were added. Stir at -78 ° C. In argon atmosphere, n-butyllithium (9.7 mL, 2.5 M in hexane, 24.25 mmol) was slowly added by a syringe, followed by stirring at room temperature for 30 minutes. Lower the temperature back to -78 ° C, then add 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (11) (5.62 mL, 27.55 mmol) The reaction was carried out for 12 hours at room temperature.

The reaction was terminated by pouring water, followed by extraction with water and diethyl ether. In the extracted diethyl ether solution, excess water was removed using Na ₂ SO ₄ and filtered to collect only diethyl ether solution. The solvent was removed from the diethyl ether solution with a rotary evaporator and separated by column chromatography (developing solvent: ethyl acetate / hexane (1:10)) to yield 2,7-bis-4,4,5,5 in 48% yield. -Tetramethyl-1,3,2-dioxaborolan-2-yl) -N- (2-ethylhexyl) carbazole was obtained.

¹ H-NMR (CDCl ₃ , δ ppm): 0.84-0.98, 1.25-1.46, 1.64-1.74 (m, 38H, -CH ₂ , -CH ₃ ), 2.05 (m, 1H, -CH-), 4.09- 4.12 (d, 2H, NCH _2- ), 7.00-7.32 (d, 2H, aromatic protons), 7.13 (s, 2H, aromatic protons), 7.90-7.93 (d, 2H, aromatic protons)

Example  14.poly ({(2- ethylhexyl ) thieno [3,4-b] thiophene -2- carboxylate } -4,6-diyl- {N- (2-ethylhexyl) carbazole} -2,7-diyl) ( PTTC Manufacture of (1)

(2-ethylhexyl) -4,6-dibromothieno [3,4-b] thiophene-2-carboxylate synthesized in Example 8 in a flame-dried 25 mL polymerization reactor with a magnetic stir bar ( 2) (0.21 g, 0.462 mmol), 2,7-bis-4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) synthesized in Example 13- N- (2-ethylhexyl) carbazole (3) (0.246 g, 0.462 mmol), trioctylmethylammonium chloride, Aliquat336 (3 drops), Pd (PPh ₃ ) ₄ (10.7 mg, 9.25 × 10 ^-6 mol) and K ₂ CO ₃ (0.63 g, 4.62 mmol) were added. After sufficiently removing oxygen by vacuum-argon circulation method, purified THF (15 mL) and degassed water (5 mL) were added in an argon atmosphere, and the temperature was raised to 85 ° C. and stirred for 72 hours. After adding 2-bromothiophene (0.2 mL), the reaction was allowed to proceed for 3 hours, followed by 2,2'-bithiophene-5-boronic acid pinacol ester (2,2'-bithiopene-5-boronic acid pinacol ester) (0.25 mL) was added. After 24 hours, the reaction was cooled to room temperature and reprecipitated in methanol (100 mL) to obtain a dark blue title polymer (weight average molecular weight: 33600).

Example  15. Celite , Florosil dialysis Molecular weight cutting method and high purity purification process

The precipitated polymer obtained in Example 14 was collected by filtration, drying, and then dissolved in chloroform to remove the catalyst with cellite and florosil. Dissolved in a small amount of chloroform and placed in a dialysis sack having a flat width of 35 mm, followed by dialysis in methanol (1 L) for 24 hours to remove oligomers, reprecipitated in methanol, filtered and dried to obtain highly purified polymer. Got it.

¹ H-NMR (CDCl ₃ , δ ppm): 0.70-2.08 (br, 34 H), 6.93-7.85 (br, 7H)

Example  16. Polymer Solutions UV - visible  Spectral characteristics

The polymer (PTTC) obtained in Example 15 and P3HT used in the present were dissolved in chloroform, respectively, and the UV-visible absorption spectrum of the solution was measured. The results are shown in FIG.

Referring to FIG. 1, the maximum absorption peak of the PTTC polymer according to the present invention was found at 628.3 and 885.4 nm, and the absorption was found to range from 500 nm to 1100 nm or more. This indicates that absorption occurs in the near-IR region as well as almost all visible regions, and it is suitable for high-efficiency solar cells through the effective absorption of solar spectrum, which is not only conventional P3HT, but also more advanced than PCPDTBT, PCDTBT, and PTB. It shows the potential as

1: transparent substrate
2: lower electrode
3: buffer layer
4: photoactive layer
5: upper electrode

Claims (18)

Carbazole-based polymer compound for organic solar cells represented by the following formula (1) having an absorption spectrum of 500nm to 1100nm.
[Formula 1]

In the above formula, R ₁ and R ₂ are each independently a linear or branched alkyl group having 1 to 10 carbon atoms, and n is an integer of 15 to 70. The carbazole polymer compound for an organic solar cell of claim 1, wherein in Formula 1, R ₁ and R ₂ are each independently an ethylhexyl group. The carbazole-based polymer compound of claim 1, wherein n is in the range of about 50 to about 50. delete (a) a thieno [3,4-b] thiophene compound of formula (2), and
(b) preparing a compound of formula 1 by copolymerizing a carbazole compound of formula 3
Method for producing a carbazole-based polymer compound for an organic solar cell comprising a.
[Formula 1]

(2)

(3)

Wherein X is each independently a halogen element, R ₁ and R ₂ are each a linear or branched alkyl group having 1 to 10 carbon atoms, and R ₃ is each -C (R ₅ ) ₂ -C (R ₅ ) ₂ Or a divalent organic group of C (R ₅ ) ₂ -CH ₂ -C (R ₅ ) _2- , wherein R ₅ is a straight or branched chain alkyl group having 1 to 10 carbon atoms, n is 15 It is an integer of -70. The method of claim 5, wherein the copolymerization reaction is carried out under a base and a palladium catalyst. The method of claim 6, wherein the base is any one selected from the group consisting of sodium carbonate, potassium carbonate, sodium hydroxide, potassium hydroxide, sodium hydrogen carbonate and potassium hydrogen carbonate. The method of claim 6, wherein the copolymerization reaction is performed at a temperature of 80 ° C. to 120 ° C. for 24 hours to 72 hours. The method of claim 5, wherein the method
Preparing a carboxylic acid compound of Chemical Formula 5 by halogenation of thieno [3,4-b] thiophene-2-carboxylic acid with halosuccinimide of Chemical Formula 4;
Preparing a thieno [3,4-b] thiophene compound of Chemical Formula 2 by reacting the carboxylic acid compound of Chemical Formula 5 with an alcohol of Chemical Formula 6 under an acid catalyst, preparing a carbazole polymer compound for an organic solar cell Way.
[Chemical Formula 4]

[Chemical Formula 5]

[Chemical Formula 6]
R ₁ -OH
In the above formula, each X is independently a halogen element, and R ₁ is a linear or branched alkyl group having 1 to 10 carbon atoms. 10. The method of claim 9, wherein the thieno [3,4-b] thiophene-2-carboxylic acid is acetic anhydride of 4,6-dihydrothieno [3,4-b] thiophene-2-carboxylic acid 5-oxide. And a method for producing a carbazole polymer compound for an organic solar cell, which is prepared by reacting with a base. The method of claim 5, wherein the method
Preparing a compound of formula 7 by nitration reaction of 4,4-dihalobiphenyl,
Preparing a chemical formula 8 by reducing the compound of formula 7;
Preparing a compound of formula 11 by reacting the carbazole compound of formula 8 with an alkyltosylate of formula 10 prepared by tosylation of formula 9;
The method of preparing a carbazole-based polymer compound for an organic solar cell further comprising the step of reacting the compound of formula 11 and the compound of formula 12 to produce a carbazole compound of formula 3.
(7)

[Chemical Formula 8]

[Chemical Formula 9]
R ₂ -OH
[Formula 10]
R ₂ -OTs
(11)

[Chemical Formula 12]

Wherein each X is independently a halogen element, R ₂ is a linear or branched alkyl group having 1 to 10 carbon atoms, and R ₃ is each -C (R ₅ ) ₂ -C (R ₅ ) ₂ -or -C (R ₅ ) is a _divalent organic group of ₂ -CH ₂ -C (R ₅ ) _2- (wherein R ₅ is a straight or branched chain alkyl group having 1 to 10 carbon atoms), R ₄ is hydrogen or 1 carbon To 10 straight or branched chain alkyl groups. The method of claim 11, wherein the compound of Chemical Formula 12 is a compound of Chemical Formula 12-1 or Chemical Formula 12-2.
[Formula 12-1]

[Formula 12-2]

In the above formula, R ₄ is hydrogen or a linear or branched alkyl group having 1 to 10 carbon atoms. The method of claim 5, wherein the compound of Formula 3 is used in a molar ratio of 1: 1 with respect to the compound of Formula 2. Transparent substrate,
A lower electrode formed on the transparent substrate,
A buffer layer formed on the lower electrode,
A photoactive layer formed on the buffer layer and comprising a carbazole polymer compound according to claim 1;
An upper electrode formed on the photoactive layer
Organic solar cell comprising a. The method of claim 14, wherein the buffer layer comprises at least one conductive material selected from the group consisting of PEDOT: PSS, polyaniline, polypyrrole, conductive metal, CuO, NiO, molybdenum oxide (MoO ₃ ), and tungsten oxide (WO ₃ ). Organic solar cells. The organic solar cell of claim 14, wherein the transparent substrate is a plastic substrate, a glass substrate, or a quartz substrate selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, aromatic polyester, and polyimide. 15. The method of claim 14, wherein the lower electrode is indium tin oxide (ITO), fluorine tin oxide (FTO), antimony tin oxide (ATO, SnO ₂ -Sb ₂ O ₃ ), gallium tin oxide (GTO), ZnO- An organic solar cell that is Ga ₂ O ₃ or ZnO-Al ₂ O ₃ . The organic solar cell of claim 17, wherein the upper electrode comprises a conductive metal such as aluminum, gold, silver, a metal alloy thereof, a metal oxide, or a conductive polymer.

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