KR20120121358A - Planar low bandgap copolymer and organic polymer thin film solar cell using the same - Google Patents

Abstract

PURPOSE: A donor-acceptor type planar copolymer is provided to obtain narrow band gap, solubility and planarity through a simple synthesis, thereby capable of effectively arranging by effective π-π stacking in a film state and to improve hole mobility and photocurrent density of a solar cell device. CONSTITUTION: A donor-acceptor type planar copolymer which has structure of narrow band gap of a donor-acceptor type is represented by chemical formula 1: (D-A)n. In chemical formula 1 D is an electron donating monomer of a bicyclic structure, A is an electron-accepting monomer of bi-cycle comprising an alkoxy group for improving solubility and providing planarity, n is an integer from 10-200, and the number average molecular weight of the alternation polymerization copolymer is 10,00-80,000 g/mol. The organic polymer thin-film solar battery comprises the alternation polymerization copolymer in a solar energy-absorbing photoactive layer.

Description

Planar copolymer with narrow band gap and organic polymer thin film solar cell device using the same {Planar low bandgap copolymer and organic polymer thin film solar cell using the same}

The present invention relates to a planar copolymer having a narrow bandgap and an organic polymer thin film solar cell device using the same. More specifically, the polymer backbone has an electron donor-electron acceptor having a narrow bandgap and planarity (donor-acceptor, DA) The present invention relates to an organic semiconductor device such as an organic solar cell and an organic transistor using an alternating copolymer of the type.

Solar cells are drawing attention as an infinite, renewable and environmentally friendly source of electrical energy. Currently, the first generation crystalline solar cell using inorganic material (most representative silicon crystalline solar cell) using inorganic material accounts for 90% of the photovoltaic power generation market. However, the cost of power generation is 5-20 times higher than that of coal, oil, and gas. As a result, second generation technology has emerged as an alternative. Second-generation thin-film solar cell market share of silicon (5.2%), CdTe (4.7%), CIGS (0.5%), etc. accounted for 10% of the total market, but it is still insignificant. However, second-generation solar cell technology also has a problem in that the manufacturing cost of the device is difficult and expensive equipment is required, resulting in high unit cost. The main reason for the increase in cost is mainly due to the process of providing a semiconductor thin film under vacuum and high temperature. Therefore, the organic polymer solar cell which can drastically lower production cost by the low temperature solution process is examined with a new possibility. At present, energy materials using organic polymers have lower photoelectric conversion efficiency than inorganic materials, but their importance is gradually increasing due to various advantages of organic materials such as device fabrication, mechanical flexibility, ease of molecular design, and price.

However, the biggest problem is that the organic solar cell using an organic semiconductor such as a conjugated polymer is lower in photoelectric conversion efficiency than the solar cell using a conventional inorganic semiconductor, and has not yet been put to practical use. As a reason for the low photoelectric conversion efficiency of the organic solar cell using the conventional conjugated polymer, the following three points are mainly mentioned. First, the absorption efficiency of sunlight is low. Secondly, in the case of an organic semiconductor, the binding energy of excitons generated by sunlight is large, so that it is difficult to separate electrons and holes. Thirdly, since traps easily trapping carriers (electrons, holes) are easily formed, the generated carriers are more likely to be trapped in the traps, and carrier mobility is low. That is, a semiconductor material generally requires high mobility of the carrier of the material, but the conjugated polymer has a problem that the mobility of charge carriers is lower than that of conventional inorganic crystalline semiconductors and amorphous silicon.

Therefore, it absorbs a lot of sunlight and separates the generated electrons and holes from excitons well and suppresses carrier trapping by trapping or trapping of carriers between the amorphous region of the conjugated polymer or the conjugated polymer chain. Developing a means to improve the temperature is a very important key for the practical application of organic semiconductor solar cells.

Photoelectric conversion elements by organic semiconductors known so far can be generally classified into the following element configurations. Schottky junctions that bond electron-donating organic materials (p-type organic semiconductors) with metals with small work functions, hetero bonds that bond electron-accepting organic materials (n-type organic semiconductors) with electron-donating organic materials (p-type organic semiconductors) Junction type etc. These devices have a low photoelectric conversion efficiency because the organic layer (about a molecular layer) in the vicinity of the junction portion contributes to photocurrent generation, and the improvement is a problem.

As a method of improving the photoelectric conversion efficiency, a bulk heterojunction type in which an electron accepting organic material (n-type organic semiconductor) and an electron donating organic material (p-type organic semiconductor) are mixed and an bonding surface contributing to photoelectric conversion is increased. There is this. Among them, photoelectric conversion devices using conjugated polymers as electron donating organic materials (p-type organic semiconductors) and semiconductor polymers having n-type semiconductor properties as electron-accepting organic materials and fullerene derivatives such as C60 have been reported. .

Currently, the biggest problem of the polymer solar cell is the photoelectric conversion efficiency is significantly lower than the inorganic structure (about 20%) such as silicon, CIGS. Therefore, the development of a photoelectric conversion element by an organic semiconductor having a high photoelectric conversion efficiency of 10% or more is urgently required. To overcome this problem, we have developed a low bandgap polymer with a broad absorption range and high molar extinction coefficient to effectively absorb sunlight, improved hole and electron mobility for high photocurrent characteristics, and polymer electrons for high open voltage. Structural control and development of polymer multilayer solar cell technology are essential.

It is an object of the present invention to provide alternating copolymers having a narrow bandgap while maintaining the planarity of the polymer backbone through simple synthesis.

In addition, another object of the present invention to provide an organic polymer thin film solar cell device using the alternating polymerization copolymer as a solar absorbing material.

Another object of the present invention is to provide an organic thin film transistor using the alternating copolymer as an active material.

In order to solve the above object, the present invention provides an alternating polymerization copolymer of a simple structure having a narrow band gap of the donor-Acceptor (D-A) type represented by the formula (1):

[Formula 1]

Wherein D is a heterocyclic electron donating monomer, A is a heterocyclic electron accepting monomer containing an alkoxy group for solubility enhancement and planarity and n is an integer from 10 to 200.

In order to achieve the above another object, the present invention provides an organic polymer thin film solar cell comprising a D-A type of an alternating polymerization copolymer having a flat structure and a narrow band gap of a simple structure according to the present invention.

In order to achieve the above another object, the present invention uses a DA-type alternating copolymer having a simple structure of planarity and narrow bandgap according to the present invention as a semiconductor layer of the organic p-type, n-type or ambipolar form Provided is a thin film transistor device.

The alternating polymerization copolymer of DA type having a flatness and a narrow bandgap of a simple structure according to the present invention can achieve a narrow bandgap through simple synthesis and ensure solubility and planarity simultaneously. Therefore, molecular alignment is possible by effective π-π stacking between films in the film state, and high mobility of charge carriers (holes) and high photocurrent density (Jsc, short circuit current, short circuit current density) are expected in solar cell device fabrication. Therefore, the polymer synthesized in the present invention may be used as a material of the photoactive layer of the organic polymer thin film solar cell device, the device may have a high photoelectric conversion efficiency (PCE).

1 is a cross-sectional view of a conventional-type (a) and inverted-type (b) organic polymer thin film solar cell device using the polymer according to the present invention.
Figure 2 shows the computer calculation results according to the Density Functional Theory of the polymer structure derivative prepared in Example 1 of the present invention.
Figure 3 shows the thermal properties results for the polymer prepared in Example 1 of the present invention.
4A and 4B show UV absorption spectra under various conditions using the polymers prepared in Examples 1 to 6 of the present invention.
5A and 5B illustrate the characteristics of Cyclic voltammogram (CV) of PTBT ₁₄ and PTTBT ₁₄ polymer films, respectively, according to an embodiment of the present invention.
6A and 6B are graphs showing photoelectric efficiency and external quantum efficiency of the solar cell device manufactured in Example 2 of the present invention, respectively.
7A and 7B illustrate organic polymer thin film transistors manufactured according to Examples 2 to 4 of the present invention, and show hole mobility, threshold voltage, and blink rate of the device.
8A and 8B illustrate organic polymer thin film transistors manufactured according to Examples 1, 5, and 6 of the present invention, and show hole mobility, threshold voltage, and blink rate of the device.

The present invention provides an alternating polymerization copolymer of a structure having a narrow bandgap of a donor-acceptor (D-A) type represented by the following formula (1):

[Formula 1]

In the above formula, D is a heterocyclic electron donating monomer, A is a heterocyclic electron accepting monomer containing an alkoxy group for improving solubility and planarity, and n is an integer of 10 to 200.

The electron donor represented by Chemical Formula 1 may be represented by the following Chemical Formula 2 or 3:

[Formula 2]

(3)

Wherein Z is N, O, S, Se, or Te.

On the other hand, the electron accepting monomer represented by A in Formula 1 may be represented by Formula 4 more specifically:

[Formula 4]

Here, R is a linear or branched alkyl group of C _{1 -20,} Q is O, S, Se, Te, N, C, or Si.

More specifically, examples of the compound having the heterocyclic electron donating monomer and the electron accepting monomer at the same time include polymers represented by the following formulas (5) to (46). n is an integer from 10 to 200.

[Chemical Formula 5]

[Formula 6]

[Formula 7]

[Formula 8]

[Chemical Formula 9]

[Formula 10]

[Formula 11]

[Chemical Formula 12]

[Chemical Formula 13]

[Formula 14]

[Formula 15]

[Chemical Formula 16]

[Chemical Formula 17]

[Chemical Formula 18]

[Formula 19]

[Chemical Formula 20]

[Chemical Formula 21]

[Formula 22]

(23)

≪ EMI ID =

(25)

(26)

(27)

(28)

[Formula 29]

(30)

(31)

(32)

(33)

[Formula 34]

(35)

(36)

[Formula 37]

(38)

[Chemical Formula 39]

[Formula 40]

(41)

(42)

(43)

(44)

[Chemical Formula 45]

(46)

[Formula 47]

(48)

(49)

(50)

(51)

(52)

(53)

[Formula 54]

(55)

(56)

(57)

(58)

[Chemical Formula 59]

(60)

(61)

[Formula 62]

(63)

≪ EMI ID =

(65)

[Formula 66]

(67)

Wherein, R is a linear or branched alkyl group of C _{1 -20,} preferably a linear or branched alkyl group of C _{6 -14.}

The polymer represented by Formula 1 according to the present invention preferably has an appropriate number average molecular weight depending on the structure. It is preferable that the number average molecular weight is 10,000 g / mol to 80,000 g / mol. If the number average molecular weight is less than 10,000 g / mol is not preferable because the physical properties are lowered and it is difficult to form a uniform thin film, if the number average molecular weight exceeds 80,000 g / mol, solubility in the organic solvent is lowered, which makes the solution process difficult Not desirable

According to the present invention, it is possible to obtain alternating copolymers having a narrow bandgap, where the term 'narrow' is used to produce a bandgap smaller than P ₃ HT (about 1.9 eV or less) in order to effectively absorb a wide range of sunlight. It means having a polymer.

The polymers according to the present invention are thiophene, furan, selenophene, telurophene, thieno [3,2, -b] thiophene, and the like. Electron-rich monomers with simple heteroaromatic ring structures and benzothiadiazloe, benzooxadiazole, benzoselenadiazole, benzotelluladiazole substituted with alkoxy It can be synthesized by copolymerizing electron-deficient monomers such as benzotelluradiazole) and benzotriizole.

The polymers of the present invention synthesized as described above can maintain the planarity by minimizing steric hindrance and the electronic effect of the alkoxy group substituted in A to obtain crystallinity and high charge mobility and current density (Jsc). have. In the case of these structures, by introducing an alkoxy substituent to give the solubility to the electron accepting monomer, it is possible to maintain a deep HOMO level without affecting the HOOC (Highest Occupied Molecular Orbital) of the final alternating copolymer. Voc, Open Circuit Voltage) can be expected. In addition, the planarity of the polymer backbone is induced by the electronic interaction between the oxygen atom of the alkoxy group and the hetero atom of the electron donor monomer, which enables molecular alignment by effective π-π stacking between molecules and charge carriers (holes). High mobility and high photocurrent density is expected in solar cell device fabrication. Therefore, the DA-type alternating copolymer of the present invention has advantages such as narrow bandgap, planarity and deep HOMO along with simple molecular structure, so that high photocurrent density (short-circuit current, Jsc), open when applied as a photoactive layer of a polymer solar cell Voltage (Voc) and energy conversion efficiency (PCE) can be achieved and an organic polymer thin film solar cell having high efficiency and oxidation stability can be fabricated.

According to another aspect of the present invention, an alternating polymerization copolymer of D-A type having a planarity and a narrow band gap can produce an organic polymer transistor device or the like by a general spin coating process.

In the organic polymer transistor device, a gate insulating layer is formed on the gate electrode substrate, an organic semiconductor layer using the alternating polymerization copolymer according to the present invention is formed on the gate insulating layer, and a metal electrode, which is a drain and a source electrode, may be formed. On the other hand, a drain and a source electrode are formed on the substrate, and after forming the organic semiconductor layer using the alternating polymerization copolymer according to the present invention, an insulating layer and a gate electrode can be formed. Therefore, the present invention can be applied to various types of thin film transistors such as a bottom gate or top gate type.

The photoactive layer of the organic polymer thin film solar cell device of the present invention blends the polymer and the fullerene derivative and includes a small amount of alkanediolol or diiodohexane as a processing additive and the device has high photoelectric conversion efficiency (PCE). Can be.

Among the compounds according to one embodiment of the present invention, as the polymer compound represented by Chemical Formula 1, for example, poly {5,6-bis (octyloxy) -4- (thiophen-2-yl) benzo [c ] [1,2,5] thiadiazole}.

The synthesis method of the compound is 2,5-bis (trimethylstenyl) thiophene (2,5-Bis (trimethylstannyl) thiophene) and 4,7-dibromo-5,6-bis (octyloxy) benzo [c ] The polymer is obtained by using [1,2,5] thiadiazole as a monomer.

Poly {5,6-bis (octyloxy) -4- (thiophen-2-yl) benzo [c] [1,2,5] thia which can be used as a photoactive layer material of the organic polymer thin film solar cell device The synthesis method of diazol} is shown in Scheme 1.

[Reaction Scheme 1]

Synthesis of Poly {5,6-bis (octyloxy) -4- (thiophen-2-yl) benzo [c] [1,2,5] thiadiazole} (PTBT)

As shown in Scheme 1, PTBT is 2,5-bis (trimethylstannyl) thiophene (2,5-Bis (trimethylstannyl) thiophene (1b) and 4,7-dibromo-5,6-bis (octyl) It can be obtained by reacting oxy) benzo [c] [1,2,5] thiadiazole (2d).

2,5-bis (trimethylstenyl) thiophene (1b) is lithiated 2,5-bromothiophene (1a) and then trimethyltin chloride It can be obtained through a stannylation reaction using.

4,7-Dibromo-5,6-bis (octyloxy) benzo [c] [1,2,5] thiadiazole (2d) can be synthesized using conventional methods known in the art, and are particularly limited. It doesn't happen. As shown in the above scheme, 1,2-dynitro-4,5-bis through a nitrification reaction, which is an electrophilic aromatic substitution of 1,2-bis (octyloxy) (2a) benzene. (Octyloxy) benzene (1,2-dinitro-4,5-bis (octyloxy) benzene) (2b) can be obtained. After catalytic reaction with tin (II) chloride, it is reacted with thionyl chloride to give 5,6-bis (octyloxy) benzo [c] [1,2,5] thiadiazole. (5,6-bis (octyloxy) benzo [ c ] [1,2,5] thiadiazole) (2c) can be obtained. The bromination reaction with Br ₂ can yield 4,7-dibromo-5,6-bis (octyloxy) benzo [c] [1,2,5] thiadiazole (2d).

Thus, PTBT, which is an alternating copolymer, is obtained from 2,5-bis (trimethylstenyl) thiophene (1b) and 4,7-dibromo-5,6-bis (octyloxy) benzo [ c] can be obtained by reacting [1,2,5] thiadiazole (2d).

The alternating polymerization copolymer of the D-A type having the planarity and narrow band gap according to the present invention can produce an organic polymer thin film solar cell or the like by a general spin coating process.

1 is a cross-sectional view of an organic polymer thin film solar cell device of a conventional type (a) and an inverted-type (b) as an organic solar cell device using an alternating copolymer according to the present invention. It is shown. Referring to FIG. 1 (a), in the organic polymer thin film solar cell device of the general type, a translucent electrode 20 is formed on a substrate 10, and the hole transport layer 30 and solar light are formed on the translucent electrode 20. The absorption organic semiconductor layer 40 is formed, and the metal electrode 50 is formed on the organic semiconductor layer 40.

Referring to FIG. 1 (b), in the inverted type organic polymer thin film solar cell device, a translucent electrode 70 is formed on a substrate 60, and the electron transport layer 80 and the sun are formed on the translucent electrode 70. The light absorbing organic semiconductor layer 90 is sequentially formed, the hole transport layer 100 is formed on the organic semiconductor layer 90, and the metal electrode 110 is formed on the hole transport layer 100. In the inverted type organic polymer thin film solar cell device, the translucent electrode 70 becomes a cathode, and the metal electrode 110 serves as an anode, and this type of inverted solar cell device is a so-called 'inverted organic solar cell'. In the solar cell of the general type, the translucent electrode acts as an anode, and the metal electrode acts as a cathode inverted (inverted) structure.

The translucent electrode 70 may be any one selected from indium tin oxide (ITO), fluorine-doped tin oxide (FTO), antimony tin oxide (ATO), and aluminum doped zinc oxide (AZO). Here, ITO is generally used as a material for forming an anode, but in the inverted organic solar cell structure according to the present invention, ITO may be used as a material for forming a cathode.

In the inverted type solar cell, the materials of the electron transporting layer and the hole transporting layer may be used differently from the general types of the electron transporting layer and the hole transporting layer. As the electron transport layer, TiO _x , ZnO, TiO ₂ , ZrO ₂ , MgO, HfO ₂ Or the like, and a metal oxide selected from the group consisting of NiO, Ta ₂ O ₃ , MoO ₃ , Ru ₂ O ₃ , and the like may be used as the hole transport layer. In addition, an organic conjugated polymer electrolyte having a cation or an anion together with a metal oxide can be used for the electron transporting layer or the hole transporting layer.

In addition to the general type of solar cell as well as the inverted type of solar cell, the photovoltaic organic semiconductor layer 90 is a narrow bandgap of a donor-acceptor (DA) type represented by Formula 1 according to the present invention. An alternating polymerization copolymer having a structure is used.

Hereinafter, the present invention will be described in more detail with reference to Examples. The following examples are intended to illustrate the present invention in detail, and the scope of the present invention is not limited by the following examples.

Example

≪ Example 1 >

Preparation of Poly {5,6-bis (octyloxy) -4- (thiophen-2-yl) benzo [c] [1,2,5] thiadiazole} (PTBT)

(1) Synthesis of 2,5-bis (trimethylstenyl) thiophene (1b)

2,5-Dibromothiophene (1 g, 4.1 mmol) was dissolved in anhydrous tetrahydrofuran (20 ml) and the temperature was cooled to -78 ° C with stirring, followed by butyllithium (1.6 M, 5.6 ml, 9 mmol) Was added slowly. After stirring the mixture for 1 hour, trimethyltin chloride (1M, 9 ml, 9 mmol) was added, and after stirring for 5 hours, the temperature was raised to room temperature and water (20 ml) was added to terminate the reaction. The organic layer was separated and dried over anhydrous magnesium sulfate, and finally, the solvent was evaporated and the residue was purified by recrystallization with ethanol to give white crystals (1.34 g, 80.0%).

¹ H-NMR (300 MHz; CDCl ₃ ; Me ₄ Si): δ (ppm) 7.4 (s, 2H), 0.36 (s, 18H).

(2) Synthesis of 5,6-bis (octyloxy) benzo [c] [1,2,5] thiadiazole (2c)

1,2-Dynetro-4,5-bis (octyloxy) benzene (2 g, 4.71 mmol) and tin (II) chloride (7.13 g, 37.56 mmol) were added to ethanol (70 ml). ) / HCl (30 ml) and refluxed at 85 ° C. for 12 h. When the temperature was lowered to room temperature, a white solid was precipitated and filtered under reduced pressure and washed with water and methanol. The filtered white solid was dried in a nitrogen atmosphere and then weighed (1.65 g, 3.77 mmol) to proceed to the next step. The solid was dissolved in dichloromethane (50 ml) and triethylamine (5.4 ml, 38.5 mmol) was added with stirring, and thionyl chloride (0.52 ml, 7.4 mmol) diluted in dichloromethane (10 ml) was added slowly. . After refluxing the mixture at 50 ° C. for 6 hours, the temperature was lowered to room temperature and water (100 ml) was added to terminate the reaction. After evaporation of dichloromethane, the resulting solid was recrystallized with ethanol after filtration under reduced pressure to give a white solid (0.9 g, 48.7%).

¹ H-NMR (300 MHz; CDCl ₃ ; Me ₄ Si): δ (ppm) 7.13 (s, 2H), 4.09 (t, 4H), 2.04-1.79 (m, 4H), 1.58-1.16 (m, 20H ), 0.95-0.81 (m, 6H).

(3) Synthesis of 4,7-Dibromo-5,6-bis (octyloxy) benzo [c] [1,2,5] thiadiazole (2d)

5,6-bis (octyloxy) benzo [c] [1,2,5] thiadiazole (1.36 g, 3.50 mmol) was dissolved in dichloromethane (100 ml) / glacial acetic acid (40 ml) and then bromine (1.20 mL, 23.6 mmol) was added slowly. The mixture was stirred at rt for 24 h and the reaction was terminated by addition of saturated aqueous NaHSO ₃ . The resulting solution was extracted with dichloromethane and washed sequentially with NaHSO ₃ solution, Na ₂ CO ₃ solution and brine. The organic phase extract was dried over anhydrous magnesium sulfate, and finally purified by evaporation of the solvent and recrystallization of the residue with ethanol to give white crystals (1.55 g, 80.4%).

¹ H-NMR (300 MHz; CDCl ₃ ; Me ₄ Si): δ (ppm) 4.16 (t, 4H), 1.97-1.81 (m, 4H), 1.62-1.46 (m, 4H), 1.46-1.19 (m , 16H), 0.88 (t, 6H).

¹³ C-NMR (75 MHz; CDCl ₃ ; Me ₄ Si): δ (ppm) 154.58, 150.23, 106.32, 75.13, 31.82, 30.24, 29.38, 29.26, 25.97, 22.66, 14.13. Elemental Analysis, Found: C, 48.09; H, 6.17; N, 5.07; S, 5.87. for C ₂₂ H ₃₄ Br ₂ N ₂ O ₂ S requires C, 48.01; H, 6.23; N, 5.09; S, 5.83%

(4) Synthesis of poly {5,6-bis (octyloxy) -4- (thiophen-2-yl) benzo [c] [1,2,5] thiadiazole} (PTBT)

2,5-bis (trimethylstenyl) thiophene (200 mg, 0.489 mmol), 4,7-dibromo-5,6-bis (octyloxy) benzo [c] [1,2,5] thiadiaza Sol (269 mg, 0.489 mmol), Pd ₂ (dba) ₃ (9.00 mg, 9.82 μmol) and tri (o-tolyl) phosphine (20.0 mg, 65.7 μmol) were dissolved in anhydrous chlorobenzene (2.50 mL). The mixture was reacted in a microwave reactor for 5 minutes at 120 ° C., 5 minutes at 140 ° C., and 40 minutes at 170 ° C. The reaction mixture was cooled to room temperature and immersed in methanol. After filtration, the polymer was purified by Soxhlet extraction in the order of acetone (12 hours), hexane (12 hours), and chloroform (6 hours). The chloroform fraction was immersed in methanol and recovered by filtration. The final result was obtained after drying in a vacuum oven (205 mg, 87.0%).

¹ H-NMR (300 MHz; CDCl ₃ ; Me ₄ Si): δ (ppm) 8.77-8.61 (m, 2H), 4.39-4.18 (m, 4H), 2.19-2.04 (m, 4H), 1.51-1.20 (m, 16H), 1.14-0.85 (m, 10H)

Number average molecular weight Mn = 30,600 g / mol (PDI = 1.7)

<Example 2>

Preparation of Poly {5,6-bis (tetradecyloxy) -4- (thiophen-2-yl) benzo [c] [1,2,5] thiadiazole} (PTBT ₁₄ )

(1) Synthesis of 2,5-bis (trimethylstenyl) thiophene

It is manufactured in the same manner as in Example 1.

(2) Synthesis of 5,6-bis (tetradecyloxy) benzo [c] [1,2,5] thiadiazole

1,2-Dynetro-4,5-bis (tetradecyl) benzene (2 g, 3.37 mmol) and tin (II) chloride (5.1 g, 26.9 mmol) were added to ethanol (150 ml). ) / HCl (20 ml) and refluxed at 85 ° C. for 12 h. When the temperature was lowered to room temperature, a white solid was precipitated and filtered under reduced pressure and washed with water and methanol. The filtered white solid was dried in a nitrogen atmosphere and then weighed (1.5 g, 2.54 mmol) to proceed directly to the next step. The solid was dissolved in dichloromethane (40 ml) and triethylamine (3.5 ml, 25.1 mmol) was added with stirring, and thionyl chloride (0.35 ml, 4.83 mmol) diluted in dichloromethane (10 ml) was added slowly. . After refluxing the mixture at 50 ° C. for 6 hours, the temperature was lowered to room temperature and water (100 ml) was added to terminate the reaction. After evaporation of dichloromethane, the resulting solid was recrystallized with ethanol after filtration under reduced pressure to give a white solid (1.2 g, 63%).

¹ H-NMR (300 MHz; CDCl ₃ ; Me ₄ Si): δ (ppm) 7.13 (s, 2H), 4.09 (t, 4H), 2.04-1.79 (m, 4H), 1.58-1.16 (m, 44H ), 0.95-0.81 (m, 6H).

(3) Synthesis of 4,7-Dibromo-5,6-bis (tetradecyloxy) benzo [c] [1,2,5] thiadiazole

5,6-bis (tetradecyloxy) benzo [c] [1,2,5] thiadiazole (1.12 g, 2.10 mmol) was dissolved in dichloromethane (60 ml) / glacial acetic acid (30 ml) and then bromine ( 0.74 mL, 14.4 mmol) was added slowly. The mixture was stirred at rt for 24 h and the reaction was terminated by addition of saturated aqueous NaHSO ₃ . The resulting solution was extracted with dichloromethane and washed sequentially with NaHSO ₃ solution, Na ₂ CO ₃ solution and brine. The organic phase extract was dried over anhydrous magnesium sulfate, and finally purified by evaporation of the solvent and recrystallization of the residue with ethanol to give white crystals (1.37 g, 90.0%).

¹ H-NMR (300 MHz; CDCl ₃ ; Me ₄ Si): δ (ppm) 4.16 (t, 4H), 1.97-1.81 (m, 4H), 1.62-1.46 (m, 4H), 1.46-1.19 (m , 40H), 0.88 (t, 6H).

(4) Synthesis of poly5,6-bis (tetradecyloxy) -4- (thiophen-2-yl) benzo [c] [1,2,5] thiadiazole (PTBT ₁₄ )

2,5-bis (trimethylstenyl) thiophene (153 mg, 0.374 mmol), 4,7-dibromo-5,6-bis (tetradecyloxy) benzo [c] [1,2,5] Thiadiazole (269 mg, 0.374 mmol), Pd ₂ (dba) ₃ (9.00 mg, 9.82 μmol) and tri (o-tolyl) phosphine (20.0 mg, 65.7 μmol) were dissolved in dry chlorobenzene (2.50 mL). I was. The mixture was reacted in a microwave reactor for 5 minutes at 120 ° C., 5 minutes at 140 ° C., and 40 minutes at 170 ° C. The reaction mixture was cooled to room temperature and immersed in methanol. After filtration, the polymer was purified by Soxhlet extraction in the order of acetone (12 hours), hexane (12 hours), and chloroform (6 hours). The chloroform fraction was immersed in methanol and recovered by filtration. The final result was obtained after drying in a vacuum oven (205 mg, 87.0%).

¹ H-NMR (300 MHz; CDCl ₃ ; Me ₄ Si): δ (ppm) 8.77-8.61 (m, 2H), 4.39-4.18 (m, 4H), 2.19-2.04 (m, 4H), 1.60-1.20 (m, 40H), 1.14-0.85 (m, 10H)

Number average molecular weight Mn = 26,000 g / mol (PDI = 1.5)

<Example 3>

Poly {5,6-bis (tetradecyloxy) -4- (thioo [3,2-b] thiophen-2-yl) benzo [c] [1,2,5] thiadiazole} (PTTBT ₁₄ )

(1) Preparation of 2,5-bis (trimethylstannyl) thieno [3,2-b] thiophene

Thieno [3,2-b] thiophene (0.3 g, 2.1 mmol) was dissolved in anhydrous tetrahydrofuran (10 ml) and the temperature was cooled to -78 ° C with stirring followed by butyllithium (2.5 M, 1.8 ml, 4.41 mmol). ) Was added slowly. The mixture was stirred at room temperature for 3 hours, and after cooling to 78 ° C., trimethyltin chloride (1M, 4.5 ml, 4.5 mmol) was added. After stirring for 5 hours, the temperature was raised to room temperature and water (20 ml) was added. The reaction was terminated. The organic layer was separated and dried over anhydrous magnesium sulfate, and finally, the solvent was evaporated and the residue was purified by recrystallization with ethanol to give white crystals (600 g, 62.0%).

¹ H-NMR (300 MHz; CDCl ₃ ; Me ₄ Si): δ (ppm) 7.26 (s, 2H), 0.36 (s, 18H).

(2) Synthesis of poly5,6-bis (tetradecyloxy) -4- (thiophen-2-yl) benzo [c] [1,2,5] thiadiazole (PTTBT ₁₄ )

2,5-bis (trimethylstannyl) thieno [3,2-b] thiophene (152 mg, 0.327 mmol), 4,7-dibromo-5,6-bis (tetradecyloxy) benzo [c] [1 , 2,5] thiadiazole (235 mg, 0.327 mmol), Pd ₂ (dba) ₃ (9.00 mg, 9.82 μmol) and tri (o-tolyl) phosphine (20.0 mg, 65.7 μmol) were dissolved in anhydrous chlorobenzene ( 4.00 mL). The mixture was reacted in a microwave reactor for 5 minutes at 120 ° C., 5 minutes at 140 ° C., and 40 minutes at 170 ° C. The reaction mixture was cooled to room temperature and immersed in methanol. After filtration, the polymer was purified by Soxhlet extraction in the order of acetone (12 hours), hexane (12 hours), and chloroform (6 hours). The chloroform fraction was immersed in methanol and recovered by filtration. The final result was obtained after drying in a vacuum oven (220 mg, 96.0%).

¹ H-NMR (300 MHz; CDCl ₃ ; Me ₄ Si): δ (ppm) 8.97-8.85 (m, 2H), 4.39-4.18 (m, 4H), 2.19-2.04 (m, 4H), 1.65-1.20 (m, 40H), 1.14-0.85 (m, 10H)

Number average molecular weight Mn = 23,000 g / mol (PDI = 3.1)

<Example 4>

Preparation of poly {5,6-bis (tetradecyloxy) -4- (selenophen-2-yl) benzo [c] [1,2,5] thiadiazole} (PSBT ₁₄ )

(1) Synthesis of 2,5-bis (trimethylstenyl) selenophene

Selenophene (0.63 g, 4.8 mmol) was dissolved in anhydrous tetrahydrofuran (10 ml) and the temperature was cooled to -78 ° C with stirring, followed by the slow addition of butyllithium (2.5 M, 4.0 ml, 10 mmol). After stirring the mixture for 1 hour, trimethyltin chloride (1M, 10 ml, 10 mmol) was added, and after stirring for 5 hours, the temperature was raised to room temperature and water (20 ml) was added to terminate the reaction. The organic layer was separated and dried over anhydrous magnesium sulfate, and finally, the solvent was evaporated and the residue was purified by recrystallization with ethanol to give white crystals (0.42 g, 20.0%).

¹ H-NMR (300 MHz; CDCl ₃ ; Me ₄ Si): δ (ppm) 7.64 (s, 2H), 0.36 (s, 18H).

(2) Synthesis of poly5,6-bis (tetradecyloxy) -4- (selenophen-2-yl) benzo [c] [1,2,5] thiadiazole (PSBT ₁₄ )

2,5-bis (trimethylstenyl) selenophene (171 mg, 0.374 mmol), 4,7-dibromo-5,6-bis (tetradecyloxy) benzo [c] [1,2,5] Thiadiazole (269 mg, 0.374 mmol), Pd ₂ (dba) ₃ (9.00 mg, 9.82 μmol) and tri (o-tolyl) phosphine (20.0 mg, 65.7 μmol) were dissolved in dry chlorobenzene (2.50 mL). I was. The mixture was reacted in a microwave reactor for 5 minutes at 120 ° C., 5 minutes at 140 ° C., and 40 minutes at 170 ° C. The reaction mixture was cooled to room temperature and immersed in methanol. After filtration, the polymer was purified by Soxhlet extraction in the order of acetone (12 hours), hexane (12 hours), and chloroform (6 hours). The chloroform fraction was immersed in methanol and recovered by filtration. The final result was obtained after drying in a vacuum oven (211 mg, 81.7%).

¹ H-NMR (300 MHz; CDCl ₃ ; Me ₄ Si): δ (ppm) 8.77-8.61 (m, 2H), 4.39-4.18 (m, 4H), 2.19-2.04 (m, 4H), 1.60-1.20 (m, 40H), 1.14-0.85 (m, 10H)

Number average molecular weight Mn = 16,000 g / mol (PDI = 2.1)

<Example 5>

Preparation of poly5,6-bis (octyloxy) -4- (thiophen-2-yl) benzo [c] [1,2,5] oxadiazole (PTBX)

(1) Synthesis of 5,6-bis (octyloxy) benzo-2,1,3-oxadiazole

1,2-dytrotro-4,5-bis (octyloxy) benzene (1.5 g, 3.5 mmol), sodium azide (1.14 g, 17.5 mmol), TBAB (0.226 g, 0.7 mmol) It was dissolved in toluene (15 mL) and then refluxed for 5 hours. After triphenylphosphine (1.l g, 4.2 mmol) was added to the reaction, the temperature was lowered to room temperature after 2 hours. The solvent was evaporated and purified by column chromatography to give the product (0.78 g, 60.0%).

¹ H-NMR (300 MHz; CDCl ₃ ; Me ₄ Si): δ (ppm) 6.78 (s, 2H), 4.09 (t, 4H), 2.04-1.79 (m, 4H), 1.58-1.16 (m, 20H ), 0.95-0.81 (m, 6H).

(2) Synthesis of 4,7-dibromo-5,6-bis (octyloxy) benzo [c] [1,2,5] oxadiazole

5,6-bis (octyloxy) benzo-2,1,3-oxadiazole (0.56 g, 1.50 mmol) is dissolved in dichloromethane (30 ml) / glacial acetic acid (10 ml) and then bromine (0.32 mL, 6.23 mmol) ) Was added slowly. The mixture was stirred at rt for 24 h and the reaction was terminated by addition of saturated aqueous NaHSO ₃ . The resulting solution was extracted with dichloromethane and washed sequentially with NaHSO ₃ solution, Na ₂ CO ₃ solution and brine. The organic phase extract was dried over anhydrous magnesium sulfate, and finally the solvent was evaporated and the residue was purified by column chromatography to give a white solid (0.60 g, 75.0%).

¹ H-NMR (300 MHz; CDCl ₃ ; Me ₄ Si): δ (ppm) 4.16 (t, 4H), 1.97-1.81 (m, 4H), 1.62-1.46 (m, 4H), 1.46-1.19 (m , 16H), 0.88 (t, 6H).

(3) poly5,6-bis (octyloxy) -4- (thiophen-2-yl) benzo [c] [1,2,5] oxadiazole (PTBX)

2,5-bis (trimethylstenyl) thiophene (200 mg, 0.488 mmol), 4,7-dibromo-5,6-bis (octyloxy) benzo [c] [1,2,5] oxadia Sol (261 mg, 0.488 mmol), Pd ₂ (dba) ₃ (9.00 mg, 9.82 μmol) and tri (o-tolyl) phosphine (20.0 mg, 65.7 μmol) were dissolved in anhydrous chlorobenzene (2.50 mL). The mixture was reacted in a microwave reactor for 5 minutes at 120 ° C., 5 minutes at 140 ° C., and 40 minutes at 170 ° C. The reaction mixture was cooled to room temperature and immersed in methanol. After filtration, the polymer was purified by Soxhlet extraction in the order of acetone (12 hours), hexane (12 hours), and chloroform (6 hours). The chloroform fraction was immersed in methanol and recovered by filtration. The final result was obtained after drying in a vacuum oven (150 mg, 67.0%).

¹ H-NMR (300 MHz; CDCl ₃ ; Me ₄ Si): δ (ppm) 8.77-8.61 (m, 2H), 4.39-4.18 (m, 4H), 2.19-2.04 (m, 4H), 1.60-1.20 (m, 16H), 1.14-0.85 (m, 10H)

Number average molecular weight Mn = 16,000 g / mol (PDI = 2.2)

<Example 6>

Preparation of poly5,6-bis (octyloxy) -4- (thiophen-2-yl) benzo [c] [1,2,5] selenadiazole (PTBS)

(1) Synthesis of 5,6-bis (octyloxy) benzo-2,1,3-celinadiazole

1,2-Dynetro-4,5-bis (octyloxy) benzene (1.57 g, 3.37 mmol) and tin (II) chloride (5.1 g, 26.9 mmol) were added to ethanol (70 ml). ) / HCl (20 ml) and refluxed at 85 ° C. for 12 h. When the temperature was lowered to room temperature, a white solid precipitated and filtered under reduced pressure and washed with water and ethanol. The filtered white solid was dissolved in ethanol (70 mL), triethylamine (5.3 mL, 38 mmol) was injected, and the temperature was increased to 85 ° C. SeO ₂ (0.4 g in 10 mL H ₂ O, 3.6 mmol) was refluxed for 2 hours after injection into the reaction. After the temperature was lowered to room temperature and ethanol was evaporated, residual inorganics were removed using chloroform and water. Purification by column chromatography (dichloromethane) and recrystallization with ethanol gave a light yellow solid (0.97 g, 60%).

¹ H-NMR (300 MHz; CDCl ₃ ; Me ₄ Si): (ppm) 6.92 (s, 2H), 4.05 (t, 4H), 2.04-1.79 (m, 4H), 1.58-1.16 (m, 20H) , 0.95-0.81 (m, 6H).

(2) Synthesis of 4,7-dibromo-5,6-bis (octyloxy) benzo [c] [1,2,5] selenadiazole

5,6-bis (octyloxy) benzo-2,1,3-selenadiazole (0.44 g, 1.00 mmol) is dissolved in dichloromethane (100 ml) / glacial acetic acid (15 ml) and then bromine (0.34 mL, 6.70 mmol) ) Was added slowly. The mixture was stirred at rt for 24 h and the reaction was terminated by addition of saturated aqueous NaHSO ₃ . The resulting solution was extracted with dichloromethane and washed sequentially with NaHSO ₃ solution, Na ₂ CO ₃ solution and brine. The organic phase extract was dried over anhydrous magnesium sulfate, and finally the solvent was evaporated and the residue was purified by column chromatography to give a solid (360 mg, 60.0%).

¹ H-NMR (300 MHz; CDCl ₃ ; Me ₄ Si): δ (ppm) 4.15 (t, 4H), 1.97-1.81 (m, 4H), 1.62-1.46 (m, 4H), 1.46-1.19 (m , 16H), 0.88 (t, 6H).

(3) poly5,6-bis (octyloxy) -4- (thiophen-2-yl) benzo [c] [1,2,5] selenadiazole (PTBS)

2,5-bis (trimethylstenyl) thiophene (200 mg, 0.488 mmol), 4,7-dibromo-5,6-bis (octyloxy) benzo [c] [1,2,5] selenadia Sol (287 mg, 0.488 mmol), Pd ₂ (dba) ₃ (9.00 mg, 9.82 μmol) and tri (o-tolyl) phosphine (20.0 mg, 65.7 μmol) were dissolved in anhydrous chlorobenzene (3.00 mL). The mixture was reacted in a microwave reactor for 5 minutes at 120 ° C., 5 minutes at 140 ° C., and 40 minutes at 170 ° C. The reaction mixture was cooled to room temperature and immersed in methanol. After filtration, the polymer was purified by Soxhlet extraction in the order of acetone (12 hours), hexane (12 hours), and chloroform (6 hours). The chloroform fraction was immersed in methanol and recovered by filtration. The final result was obtained after drying in a vacuum oven (180 mg, 70.8%).

¹ H-NMR (300 MHz; CDCl ₃ ; Me ₄ Si): δ (ppm) 8.77-8.61 (m, 2H), 4.39-4.18 (m, 4H), 2.19-2.04 (m, 4H), 1.60-1.20 (m, 16H), 1.14-0.85 (m, 10H)

Number average molecular weight Mn = 20,000 g / mol (PDI = 1.7)

Fabrication of Organic Polymer Thin Film Transistor Devices

200 nm of SiO ₂ , a gate insulator film, was deposited on an antimony doped Si wafer (resistance: 0.008-0.02 ohm / cm) using an e-beam evaporator and then acetone and isopropyl alcohol. After washing, soak in toluene for 1 minute in a mixed solution of 1% by weight of octanetrichlorosilane (OTS) (99: 1 volume%), and then wash with a clean toluene solution. Spin the solution of PTBT, PTBT ₁₄ , PTTBT ₁₄ , PSBT ₁₄ , PTBX, and PTBS prepared in Examples 1 to 6 in chlorobenzene at 2000 rpm for 60 seconds on the substrate treated with OTS. The coating formed a polymer semiconductor layer about 60 nm thick. The device was placed in a thermal evaporator, and the organic polymer thin film transistor was deposited by depositing a gold (Au) metal with a thickness of about 60 nm as a drain and a source electrode on the polymer semiconductor layer under a vacuum of less than 10 ⁻⁶ Torr. The device was produced.

The alternating polymerization copolymer of DA type having planarity and narrow band gap according to the present invention can manufacture organic polymer transistor devices and the like by a general spin coating process.

Typical type ( Conventional - type ) Fabrication of Organic Polymer Thin Film Solar Cell Devices

After UV ozone treatment of the washed ITO transparent electrode for 10 minutes, poly {3,4-ethylenedioxythiophene} / polystyrene sulfonic acid (PEDOT: PSS) (manufactured by Heraeus, trade name: CLEVIOS) was used for 5000 rpm for 40 seconds. Spin coating and drying for 10 minutes at 140 ℃ to form a PEDOT: PSS layer of about 40nm thickness. 1 wt% of PTBT, PTBT ₁₄ , PTTBT ₁₄ , PSBT ₁₄ , PTBX and PTBS prepared in Examples 1 to 6 and 2 wt% of PC61BM ([6,6] -phenyl-C61-butyric acid methylester), respectively (chlorobenzene) and 1,8-octanedithiol (1,8-octanedithiol) (ODT) (98: 2% by volume) mixed solution dissolved in a mixed solvent by spin coating on the PEDOT: PSS layer for 1700rpm, 60 seconds A 100 nm thick solar absorption organic semiconductor layer was formed. The organic polymer thin film solar cell device was formed by depositing aluminum (Al) to a thickness of about 100 nm with a metal electrode on the solar absorption layer in a vacuum state of less than 10 ^-6 Torr in a thermal evaporator. Produced.

Fabrication of Inverted-type Organic Polymer Thin Film Solar Cell Devices

After UV ozone treatment of the washed ITO electrode for 10 minutes, the titanium oxide (TiO _X ) precursor solution was spin-coated at 5000 rpm for 40 seconds and heat-treated at 80 minutes for 10 minutes to form a TiO _X layer having a thickness of about 20 nm. After forming a solar-absorbing organic semiconductor layer under the same conditions as a general type of solar cell, a molybdenum oxide (MoO ₃ ) of about 5 nm thickness was deposited with a hole transport layer using a thermal vacuum evaporator, and a gold (Au) metal electrode was continuously formed. Was deposited to a thickness of about 100nm to produce a solar cell device.

Evaluation results

Computer calculation

FIG. 2 shows (B3LYP / 6-31G ^** ) the results of computer calculations according to Density Functional Theory of the polymer derivative prepared in Example 1. Alkyl groups were fixed with methyl groups for ease of calculation. In the case of TB without an alkyl group, the back face has a flatness of 180 °, but when the alkyl group is substituted with thiophene or benzothiadiazole like MeTB and TMeB, the planarity is broken due to steric hindrance. In the case of TMeOB, which is the polymer PTBT derivative structure of Example 1, the back angle is 190 °, and the back angle is similar to that of TB, which is caused by electronic interaction between the oxygen atom of the alkoxy group and the hetero atom of the electron donating monomer. The results show that planarity is derived.

Thermal properties

Figure 3 shows the thermal properties of the polymer prepared in Example 1. Figure 3 shows the results of measurement by TGA and DSC in a nitrogen atmosphere at 10 ℃ / min heating rate, the polymer of the present invention was thermally stable showing a weight loss of less than 5% up to 343 ℃. PTBT showed melting point and recrystallization peak at 236 ° C and 220 ° C, respectively. This property appears to be due to the improved crystallinity due to the planarized molecular structure. The planarized molecular structure can be said to affect the degree of crystallinity of the polymer by improving the interaction between the chains.

Optical properties

4A shows UV absorption spectra in the chlorobenzene solution and film state of PTBT, PTBX, PTBS. The three kinds of polymers have a structure in which the S atoms of the benzothiadiazole groups are electron-substituted with O and Se atoms, respectively, based on PTBT.

Referring to FIG. 4A, the light absorption band of a wide range in the visible light region of 400 nm to 750 nm can be confirmed. The optical bandgaps (Eg) of the three polymers were estimated to be 1.72 eV, 1.72 eV, and 1.68 eV, respectively, based on the onset point of the absorption spectrum in the film. It can be seen that the substitution of S atoms with O atoms does not significantly affect the band gap. In the case of PTBT and PTBX, peaks by molecular chain-stacking were also observed in solution, and the interaction peak was increased at the same time as red-shift during film production. However, only red shift was observed for PTBS. PTBT and PTBX, which have high intermolecular interactions, are expected to perform well in both solar cells and transistors due to their high crystallinity and narrow bandgap.

Figure 4b shows the UV absorption spectrum in the chlorobenzene solution and film state of PTBT ₁₄ , PSBT ₁₄ , PTTBT ₁₄ . The three types of polymers have a structure in which an electron donor material is substituted with selenophene and thieno [3,2-b] thiophene based on PTBT ₁₄ .

Referring to FIG. 4B, it can be seen that all polymers have a wide range of light absorption bands in the visible light region of 400 nm to 750 nm. In particular, it represents an electron donor improving the ability (PSBT ₁₄₎ and thiophene to increased due to the expanded structure of pi-pi interaction (PTTBT ₁₄₎ narrower band gap than the PTBT ₁₄ for PSBT ₁₄ and PTTBT ₁₄ Able to know. In particular, PSBT ₁₄ and PTTBT ₁₄ showed distinct vibronic shoulder peaks due to intermolecular interactions not only in film but also in solution, and PTBT ₁₄ showed an increase in vibronic shoulder peaks when made into film. It can be predicted that PSBT ₁₄ and PTTBT ₁₄ show better crystallinity than PTBT ₁₄ . The optical bandgap (E _g ) of the polymer was estimated to be 1.74, 1.62 and 1.70 eV, respectively, based on the onset point of the absorption spectrum in the film. Substituting thiophene with selenophene, which has excellent electron donating ability, has a great effect on reducing the band gap. UV absorption results are expected that all three polymers will give a broad absorption spectrum, resulting in increased current density.

Electrochemical properties

Figure 5a shows the characteristics of the cyclic voltammogram (CV) of the typical polymer PTBT ₁₄ and PTTBT ₁₄ polymer film, the HOMO / LUMO values of all the polymers are shown in Table 1 and Table 2.

HOMO (eV) LUMO (eV) E _g (eV) PTBT -5.41 -3.54 1.87 PTBX -5.46 -3.61 1.85 PTBS -5.26 -3.59 1.67

HOMO (eV) LUMO (eV) E _g (eV) PTBT ₁₄ -5.49 -3.55 1.94 PSBT ₁₄ -5.33 -3.56 1.77 PTTBT ₁₄ -5.32 -3.57 1.75

Specifically, CV was measured at a scanning rate of 50 mV / s in 0.1 M of a solution of tetrabutylammonium tetrafluoroborate (Bu ₄ NBF ₄ ) in acetonitrile. Platinum (Pt) electrode was coated with a polymer film by dip coating and used as a working electrode. Ag / AgNO ₃ The electrode was used as a reference electrode.

The polymers HOMO and LUMO levels of the present invention were calculated from the oxidation and reduction starting point potential for ferrocene as an internal reference.

Referring to Table 1, when the S atom is substituted with an O atom, HOMO and LUMO levels are slightly lowered due to improved electronegativity, which benefits the high open voltage of the solar cell. In the case of PTBS, the HOMO level is improved by Se atoms, and the narrow band gap may increase the current density, but the open voltage is expected to decrease. The LUMO levels of all three polymers showed similar values, ranging from -3.5 to -3.6 eV, and have a sufficient energy offset for exciton separation from PCBM.

Table 2 shows HOMO / LUMO energy levels of PTBT ₁₄ , PSBT ₁₄ , PTTBT ₁₄ . PTBT ₁₄ shows slightly lower HOMO levels compared to PTBT, which may be the result of the increase in non-conductive alkyl groups. For PSBT ₁₄ improved the HOMO level by Se atoms as in the PTBS, due to the case of PTTBT ₁₄ extended structure and high crystallinity appears similar HOMO level and PSBT _14. All three polymers show similar LUMO levels around -3.56 eV, probably due to the use of the same electron acceptor material, showing a sufficient offset for exciton separation. These results indicate that all six polymers have energy levels suitable for solar cell and p-type transistor applications.

Photoelectric  characteristic

6A and 6B show photoelectric efficiency and external quantum efficiency of a typical structure of a conventional-type solar cell manufactured in Example 2 of the present invention, and the data of all devices are shown in Table 3 below.

Photoactive layer Jsc
(mA / cm ² ) Voc
(V) FF PCE
(%) PTBT ₁₄ : PC ₆₁ BM + 2% ODT 9.34 0.88 0.68 5.56 PSBT ₁₄ : PC ₆₁ BM 9.80 0.71 0.48 3.37 PTTBT ₁₄ PC ₆₁ BM + 2% DIHODT 9.56 0.73 0.49 3.43 PTBT: PC ₆₁ BM + 2% ODT 10.50 0.87 0.65 5.87 PTBS: PC ₆₁ BM 2.66 0.83 0.32 0.71 PTBX: PC ₆₁ BM + 2% ODT 6.78 0.89 0.46 2.76

Referring to Table 3, the values of V _OC , J _SC , and FF are PTTBT ₁₄ in the conventional solar cell devices. 0.73 V, 9.56 mA / cm ² , 0.49, PSBT ₁₄ measured 0.71 V, 9.80 mA / cm ² , 0.48, and PTBT ₁₄ measured 0.88 V, 9.34 mA / cm ² , 0.68, and the final photoelectric efficiency was 100 mW / in light of ² cm it was measured, respectively 3.43, 3.37, and 5.56%.

In the case of the measured PTBT ₁₄ , V _OC represents the highest level among solar cell devices using a thiophene copolymer as the solar absorption photoactive layer. In addition, the device shows a high external quantum efficiency over a wide wavelength range of 300nm to 800nm, it was confirmed that the device absorbs light in the entire visible light region to show an efficient photoelectric effect. In particular, the external quantum efficiency was about 50% or more in the spectral range of 400 to 700 nm.

PTBT, PTBS, PTBX The photovoltaic efficiencies of 5.87, 0.71, and 2.76% were observed in 100 mW / cm ² light of conventional solar cell devices. V _OC , J _SC , FF values 0.87 V, 10.05 mA / cm ² , 0.65 for PTBT, 0.83 V, 2.66 mA / cm ² , 0.32 for PTBS, 0.89 V, 6.78 mA / cm ² , 0.46 Was measured. In addition, an inverted-type solar cell device was fabricated using PTBT as a photoactive layer. As a result, V _OC , J _SC , and FF values were 0.85 V, 9.64 mA / cm ² , and 0.64, respectively. Photoelectric efficiency of% was shown.

Organic Thin Film Transistor Characteristics

7A and 7B illustrate organic polymer thin film transistors using PTBT ₁₄ , PSBT ₁₄ , and PTTBT ₁₄ polymer copolymers, and show hole mobility, threshold voltage, and blink rate of the device.

The mobility (m) of the hole can be obtained through Equation 1 below using the gate voltage V _gs compared to the drain current I _ds in saturation.

&Quot; (1) &quot;

I _ds = ( WC _i / 2L) × μ × ( V _gs - V _T ) ²

W is the device width, L is the device length, C _i is the capacitance of SiO ₂ , and V _T is the threshold voltage.

FIG. 7A is a graph showing I _ds versus V _gs, and a flashing ratio can be obtained, and PTBT ₁₄ , PSBT ₁₄ , and PTTBT ₁₄ represent 4.00 × 10 ⁴ , 8.14 × 10 ⁴ , and 1.15 × 10 ⁵ , respectively. FIG. 7B is a graph showing the inverse square root of I _ds , and the threshold voltage and mobility can be obtained through its linear function. The threshold voltages of PTBT ₁₄ , PSBT ₁₄ and PTTBT ₁₄ are -6.72 V, 16.74 V and -2.83 V, respectively, and the mobility is 0.24 cm ² / Vs, 0.044 cm ² / Vs and 0.42 cm ² / Vs. These values are summarized in Table 4.

Polymer Flashing rain Threshold voltage
(V) Mobility
(cm ² V ^-1 s ^-1 ) PTBT ₁₄ 4.00 x 10 ⁴ -6.72 0.24 PSBT ₁₄ 8.14 x 10 ⁴ 16.74 0.044 PTTBT ₁₄ 1.15 x 10 ⁵ -2.83 0.42

Referring to Table 4, in the mobility results, PTBT ₁₄ having a relatively small S group substituted in the electron donor showed higher hole mobility than the polymer polymer PSBT ₁₄ having a large Se substitution. PTBT ₁₄ is due to the coupling angle between the electron donor and the receiver The curved chain structure is shown. In order to improve this, a heterocyclic structure can be introduced to synthesize PTTBT ₁₄ , and a polymer chain structure having increased linearity can be synthesized.

This makes the polymer chain-to-stacking well in the organic polymer thin film transistor device to increase the mobility of the hole nearly double.

8A and 8B illustrate an organic polymer thin film transistor using PTBT, PTBS, and PTBX polymer copolymers in the present invention, showing hole mobility, threshold voltage, and blink ratio of the device.

8A is a graph showing I _ds vs. V _gs, and the blinking ratio can be obtained, and the point-by-point ratios of PTBT, PTBS, and PTBX represent 3.99 x 10 ⁴ , 4.86 x 10 ³ , and 5.53 x 10 ² , respectively. FIG. 8B is a graph showing square root of I _ds , and the threshold voltage and mobility can be obtained through its linear function. The threshold voltages of PTBT, PTBS, and PTBX are 6.54 V, -29.18 V, and -17.62 V, respectively, and the mobility is 0.0368 cm ² / Vs, 0.0119 cm ² / Vs, and 0.0045 cm ² / Vs, respectively. These values are summarized in Table 5.

Polymer Flashing rain Threshold voltage
(V) Mobility
(cm ² V ^-1 s ^-1 ) PTBT 3.99 x 10 ⁵  6.72 0.0368 PTBS 4.86 x 10 ³ -29.18 0.0119 PTBX 5.53 x 10 ² -17.62 0.0045

Referring to Table 5, in the result of mobility and flashing ratio, the PTBT substituted with a relatively small S accepts electrons, and shows higher hole mobility than the polymer polymer PTBS substituted with a larger Se. This makes the interchain stacking well in the organic polymer thin film transistor device to increase the mobility of the hole nearly three times. In addition, PTBX with O-substituted electrons traps electrons, which shows that the flashing ratio and mobility are worse than that of PTBT and PTBS.

The thermal, optical, electrochemical, photoelectric and organic thin film transistor characteristics of the evaluation results show that the polymer material according to the present invention exhibits excellent characteristics and can be used as an effective solar absorption photoactive layer material in organic thin film solar cell devices. can confirm.

Claims (15)

An alternating polymerization copolymer of a structure having a narrow bandgap of a donor-acceptor (DA) type represented by Formula 1 below:
[Formula 1]

Wherein D is an electron donating monomer of a heterocyclic structure, A is an electron accepting monomer of a heterocyclic ring containing an alkoxy group for improving solubility and planarity, and n is an integer of 10 to 200.
The alternating copolymer of claim 1, wherein in Formula 1, D is an electron donating monomer having a heterocyclic structure represented by Formula 2 or 3 below:
(2)

(3)

Wherein Z is N, O, S, Se, or Te.
The alternating copolymer of claim 1, wherein A in Formula 1 is an electron donating monomer having a heterocyclic structure represented by Formula 4.
[Chemical Formula 4]

Here, R is a linear or branched alkyl group of C _{1 -20,} Q is O, S, Se, Te, N, C, or Si.
The alternating copolymer according to claim 1, wherein Formula 1 has a heterocyclic electron monomer and an electron accepting monomer selected from Formulas 5 to 67 at the same time:

[Chemical Formula 5]

[Chemical Formula 6]

(7)

[Chemical Formula 8]

[Chemical Formula 9]

[Formula 10]

(11)

[Chemical Formula 12]

[Chemical Formula 13]

[Chemical Formula 14]

[Chemical Formula 15]

[Chemical Formula 16]

[Chemical Formula 17]

[Chemical Formula 18]

[Chemical Formula 19]

[Chemical Formula 20]

[Chemical Formula 21]

[Chemical Formula 22]

(23)

[Formula 24]

[Formula 25]

[Formula 26]

[Formula 27]

[Formula 28]

[Formula 29]

[Formula 30]

(31)

(32)

[Formula 33]

(34)

(35)

(36)

(37)

(38)

[Chemical Formula 39]

(40)

(41)

(42)

(43)

(44)

[Formula 45]

(46)

(47)

[Formula 48]

(49)

(50)

[Formula 51]

[Formula 52]

[Formula 53]

(54)

(55)

(56)

[Formula 57]

(58)

[Chemical Formula 59]

[Formula 60]

(61)

(62)

(63)

&Lt; EMI ID =

(65)

(66)

(67)

Wherein, R is a linear or branched alkyl group of C _{1 -20.}
5. The method of claim 4, wherein R is an alternating copolymer the polymerization, characterized in that C _{6 -14.}
The compound of claim 1, wherein Formula 1 is poly {5,6-bis (octyloxy) -4- (thiophen-2-yl) benzo [c] [1,2,5] thiadiazole} (PTBT) An alternating polymerization copolymer, characterized in that
The alternating copolymer of claim 1, wherein the number average molecular weight is 10,000 g / mol to 80,000 g / mol.
8. The alternating copolymer of claim 7 wherein the number average molecular weight is 30,000 g / mol to 40,000 g / mol.
An organic polymer thin film solar cell, wherein the solar absorption photoactive layer comprises an alternating polymerization copolymer according to any one of claims 1 to 8.
An inverted type organic polymer thin film solar cell, wherein the solar absorbing photoactive layer comprises an alternating polymerization copolymer according to any one of claims 1 to 8.
The method of claim 10, wherein the hole transport layer in the solar cell is inverted, characterized in that at least one metal oxide selected from the group consisting of NiO, Ta ₂ O ₃ , MoO ₃ , Ru ₂ O ₃ , an organic cation and an anionic conjugated polymer electrolyte Type organic polymer thin film solar cell.
The method of claim 10, wherein the electron transport layer in the solar cell is TiO _x , ZnO, TiO ₂ , ZrO ₂ , MgO, HfO ₂ , An inverted type organic polymer thin film solar cell, characterized in that one selected from the group consisting of an organic cation and an anionic conjugated polymer electrolyte.
The organic polymer thin film solar cell according to claim 9 or 10, wherein the photoabsorption photoactive layer comprises alkanedithiol as an additive.
The organic polymer thin film solar cell of claim 13, wherein the solar absorption photoactive layer comprises 1,8-octanedithiol (ODT) as an additive.
An organic thin film transistor comprising the alternating polymerization copolymer according to any one of claims 1 to 8 as an active material.

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