KR101741535B1 - Method for orienting copolymer backbone comprising thiophene derivates - Google Patents

Abstract

The present invention relates to a copolymer represented by the following general formula (1). When the copolymer of the present invention is crystallized on a substrate using a copolymer comprising a thiophene and a thiophene derivative, the ratio of the main chain oriented in the horizontal direction to the substrate is increased, and the ratio of π-π Stacking (pi-pi stacking) can be improved. In addition, such a copolymer can be applied to various devices such as transistors, flexible electronic devices, and wearable devices to improve device characteristics such as charge mobility.
[Chemical Formula 1]

Description

METHOD FOR ORIENTING COPOLYMER BACKBONE COMPRISING THIOPHENE DERIVATES BACKGROUND OF THE INVENTION [0001]

The present invention relates to a copolymer containing a thiophene derivative and a method for aligning the main chain of the copolymer, and more particularly, to a method for orienting a main chain of a copolymer on a substrate, ≪ / RTI > copolymers and copolyester main chains.

Since the late 1970s it has been known that electrical conductivity can reach nearly copper through appropriate doping of certain organic materials, current organic materials are now found to be semiconductors, conductors (such as doped polyacetylene) from the best insulators (polystyrene, etc.) In addition, all kinds of electronic materials can be obtained from superconductors (TMTSF) 2PF6, perchlorate, pentacene, etc.). Examples of semiconductors include p-type pentacene, n-type C60, and Alq _3. Dielectric materials include polyvinylidene fluoride (PVDF), which is a ferroelectric material, and copolymers based thereon.

Organic thin film transistors using organic materials have been studied in the next generation smart cards as well as in the use of active driving elements for organic EL. Also, after the results of research on the electric oscillation characteristics using an organic semiconductor as an active layer have been announced, much attention has been paid to the applicability as a laser diode. In addition, the efficiency of the solar cell made of doped pentacene reaches 2.4%, which is remarkably improved, and the production cost of the device is significantly lower than that of non-organic materials.

In addition, flexible electronic circuit boards are expected to become an important element in the future industry. Therefore, development of organic thin film transistors capable of meeting these demands is becoming an important research field. Organic thin film transistors can not be used for high-speed devices such as silicon (Si) or germanium (Ge) because of their low charge mobility due to the nature of organic semiconductors. However, they are used when devices are manufactured over a large area, Organic thin film transistors can be useful, especially since low cost processes are possible. Recently, Phillips researchers have published a programmable code generator consisting of 326 transistors made of polymeric materials, including substrates, electrodes, organic dielectrics (insulators), and organic semiconductors.

The organic thin film transistor implemented on a plastic substrate can be applied to driving a bendable liquid crystal display device or an electronic paper and an organic light emitting device which have recently attracted great interest. In particular, recently developed electronic paper is a display device which does not require a high charge mobility and a high speed switching speed due to voltage driving, and is an advantageous technology to be applied to a large area capable of bending, so that the application of the organic thin film transistor is very high.

Research on organic thin film transistors has started in the early 1980s and has been under full-fledged research in recent years. The transistor element consists of a substrate, a gate electrode, an insulating film, a channel layer, a source / drain electrode, and a protective layer to prevent external moisture and oxygen permeation. The organic thin film transistor is fabricated by replacing the existing silicon based inorganic material with the organic compound or the polymer material which exhibits the semiconductor characteristic, which is the key part of the charge transfer which has the greatest influence on the device characteristics. Polyacene compounds such as anthracene, tetracene, and pentacene have been studied along with polyphenylene vinylene, polypyrrole, polythiophene, and oligothiophene as organic semiconductor materials. Particularly, It has a high crystallinity and thus has a high carrier mobility. Organic semiconductor materials are classified into n-type materials for transporting electrons and p-type materials for transporting holes. Currently, organic semiconductor materials such as pentacene and poly (3-hexylthiophene) (P3HT) exhibit high charge mobility among p-type organic semiconductors.

A polyacene compound, such as pentacene, is a compound that is derived from an aromatic molecule between neighboring molecules. It has been reported that it has high crystallinity and excellent charge mobility characteristics because of its strong affinity. According to a recent announcement, a high charge mobility of 3.2 to 5.0 cm ² / Vs has been reported with Lucent Technologies and 3 M using pentacene single crystals (Mater. Res. Soc. Symp. ~ L6.5.11 (2003)). CNRS in France has reported relatively high charge mobility and current flicker ratios of 0.01-0.1 cm ² / Vs using oligothiophene derivatives. However, since the above-mentioned conventional technique uses a vacuum deposition process to manufacture a thin film necessary for manufacturing a device, expensive vacuum equipment is required, and the process is complicated and the process cost is high.

Another representative p-type organic semiconductor material, poly (3-hexylthiophene), has a strong? -Molecular attractive force so that a thin film formed on a substrate forms a highly crystalline nanofiber network , And realize excellent device performance. However, when a poly (3-hexylthiophene) thin film formed on a substrate has a high proportion of a main chain oriented in a vertical direction on a substrate and is applied to an electronic device such as a transistor due to high contact resistance with a gate insulating film, There is a problem that the characteristics of the semiconductor device are deteriorated.

The object of the present invention is to solve the above problems and it is an object of the present invention to increase the ratio of the main chain oriented in the horizontal direction to the substrate when crystallizing on a substrate using a copolymer comprising thiophene and thiophene derivatives, Which can further improve the pi-pi stacking of the crystals of the coalescence.

It is another object of the present invention to provide an electronic device, such as a transistor, having improved device characteristics such as charge mobility by applying such a copolymer.

According to an aspect of the present invention,

There is provided a copolymer represented by the following formula (1).

[Chemical Formula 1]

In formula (1)

R is a C3 to C20 linear or branched alkyl group,

n and m are the number of repeating units,

The number average molecular weight (M _n) is 3,000 to 500,000.

The R may be a linear alkyl group of C3 to C10.

The R may be a hexyl group.

According to another aspect of the present invention,

There is provided a process for producing a copolymer which comprises polymerizing a compound represented by the following formula (2) and a compound represented by the following formula (3) to produce a compound represented by the following formula (1).

[Chemical Formula 1]

In formula (1)

R is a C3 to C20 linear or branched alkyl group,

n and m are the number of repeating units,

The number average molecular weight (M _n) is 3,000 to 500,000.

(2)

In formula (2)

R is a C3 to C20 linear or branched alkyl group,

X ¹ and X ² are the same as or different from each other, and X ¹ and X ² are each independently a halogen atom.

(3)

In formula (3)

X ³ and X ⁴ are the same as or different from each other, and each of X ³ and X ⁴ is independently a halogen atom.

The method for producing a copolymer as described above,

(1) preparing a solution containing a compound represented by Formula 2, a compound represented by Formula 3, and a magnesium compound; And (2) adding a polymerization initiator to the solution to prepare a copolymer.

The R may be a linear alkyl group of C3 to C10.

The magnesium compound may include at least one member selected from the group consisting of isopropyl magnesium chloride, isopropyl magnesium bromide, tert-butyl magnesium chloride, and tert-butyl magnesium bromide.

The polymerization initiator may include at least one selected from Ni (dppp) Cl ₂ , Ni (dppe) Cl ₂ , and Ni (dppf) Cl ₂ .

According to another aspect of the present invention,

An electronic device comprising the copolymer is provided.

According to another aspect of the present invention,

A transistor comprising the copolymer is provided.

The transistor

A gate electrode formed on the substrate; A gate insulating film for insulating the gate electrode; And a source electrode and a drain electrode formed on the gate insulating layer, wherein the semiconductor layer is located between the source electrode and the drain electrode, or the source electrode and the drain electrode are located on the semiconductor layer, The semiconductor layer may include the copolymer.

The copolymer may form? -Π stacking.

The copolymer may include a copolymer in which the main chain of the copolymer is oriented in the horizontal direction with the surface of the gate insulating film.

According to another aspect of the present invention,

(a) preparing a copolymer represented by the following formula (1); And (b) crystallizing the copolymer on the substrate to orient the main chain of the copolymer.

[Chemical Formula 1]

In formula (1)

R is a C3 to C20 linear or branched alkyl group,

n and m are the number of repeating units,

The number average molecular weight is 3,000 to 500,000.

The orientation of the main chain of the copolymer can be controlled based on the plane direction of the substrate by adjusting the ratio of n: m in the formula (1).

n: m may be from 1:10 to 1: 1.5.

Wherein step (b) comprises: (b-1) dissolving the copolymer in an organic solvent to prepare a copolymer solution; (b-2) coating the copolymer solution on a substrate; And (b-3) drying and crystallizing the copolymer solution coated on the substrate to orient the main chain of the copolymer.

The solvent may include at least one solvent selected from the group consisting of tetrahydrofuran, chloroform, dichloromethane, chlorobenzene, dichlorobenzene, trichlorobenzene, toluene, and p-xylene.

In the step (b-2), a method of coating the copolymer solution on a substrate may be a spin coating method, an inkjet coating method, a dip coating method, a drop casting method and a bar coating method bar coating.

The drying temperature may be 80 to 250 ° C.

Unlike the prior art, when the copolymer of the present invention is crystallized on a substrate using a copolymer containing a thiophene and a thiophene derivative, the ratio of the main chain oriented in the horizontal direction to the substrate is increased, Pi stacking (pi-pi stacking).

In addition, such a copolymer can be applied to various devices such as transistors, flexible electronic devices, and wearable devices, which have greatly improved device characteristics such as charge mobility.

FIG. 1 is a nuclear magnetic resonance (NMR) spectrum of a polymer prepared according to Examples 1 to 3 and Comparative Example 1. FIG.
FIG. 2 shows DSC (differential scanning calorimetry) analysis results of the polymer thin films prepared according to Examples 4 to 6 and Comparative Example 2. FIG.
Fig. 3 shows the results of UV-vis absorption spectrum analysis of the polymer thin films prepared according to Examples 4 to 6 and Comparative Example 2 before and after annealing.
FIG. 4 shows X-ray scattering pattern measurement results of the polymer thin films prepared according to Examples 4 to 6 and Comparative Example 2. FIG.
FIG. 5 shows the NEXAFS (near-edge X-ray absorption fine structure) analysis results of the polymer thin films prepared according to Example 6 and Comparative Example 2. FIG.
6 shows the results of measurement of the charge carrier mobility of the transistor manufactured according to the device embodiments 1 to 3 and the device comparative example 1. FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention.

However, the following description does not limit the present invention to specific embodiments. In the following description of the present invention, detailed description of related arts will be omitted if it is determined that the gist of the present invention may be blurred .

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises ", or" having ", and the like, specify that the presence of stated features, integers, steps, operations, elements, or combinations thereof, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, or combinations thereof.

Also, when an element is referred to as being "formed" or "laminated" on another element, it may be formed or laminated directly on the front surface or one surface of the other element, It will be appreciated that other components may be present in the < / RTI >

As used herein, unless otherwise defined, the term "alkyl group" means an aliphatic hydrocarbon group.

The alkyl group may be a "saturated alkyl group" which does not contain any double or triple bonds.

The alkyl group may be an "unsaturated alkyl group" comprising at least one double bond or triple bond.

The alkyl group may be a C1 to C50 alkyl group. More specifically, the alkyl group may be a C1 to C20 alkyl group, a C1 to C10 alkyl group or a C1 to C6 alkyl group.

For example, the C1 to C4 alkyl groups may have 1 to 4 carbon atoms in the alkyl chain, i.e., the alkyl chain may be optionally substituted with one or more substituents selected from the group consisting of methyl, ethyl, propyl, iso-propyl, n-butyl, Indicating that they are selected from the group.

Specific examples of the alkyl group include a methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, t-butyl group, pentyl group, hexyl group, ethenyl group, Butyl group, cyclopentyl group, cyclohexyl group, and the like.

Hereinafter, the copolymer of the present invention will be described in detail. However, it should be understood that the present invention is not limited thereto, and the present invention is only defined by the scope of the following claims.

The copolymer of the present invention is represented by the following formula (1).

[Chemical Formula 1]

In formula (1)

R is a C3 to C20 linear or branched alkyl group,

n and m are the number of repeating units,

The number average molecular weight is 3,000 to 500,000.

The R may preferably be a straight-chain alkyl group of C3 to C10, and more preferably a hexyl group.

The copolymer may be a random copolymer other than a block copolymer and the amount of each repeating unit included in the main chain may be varied depending on the feed ratio of the raw material during the production of the copolymer have. As the amount of repeating units increases and decreases, the positional regularity of the side chain changes, and thus the crystallinity and π-π stacking of the copolymer may increase or decrease.

Hereinafter, a method for producing the copolymer of the present invention will be described.

A compound represented by the following formula 2 and a compound represented by the following formula 3 are polymerized to prepare a compound represented by the following formula 1, that is, the copolymer of the present invention.

(2)

In formula (2)

R is a C3 to C20 linear or branched alkyl group,

X ¹ and X ² are the same as or different from each other, and X ¹ and X ² are each independently a halogen atom.

(3)

In formula (3)

X ³ and X ⁴ are the same as or different from each other, and each of X ³ and X ⁴ is independently a halogen atom.

[Chemical Formula 1]

In formula (1)

R is a C3 to C20 linear or branched alkyl group,

n and m are the number of repeating units,

The number average molecular weight is 3,000 to 500,000.

The R may be a C3 to C10 linear alkyl group.

X ¹ to X ⁴ are the same or different from each other, and each independently may be a bromine atom or an iodine atom, preferably a bromine atom.

The method for preparing the copolymer of the present invention will be described in more detail. First, a solution containing the compound represented by Formula 2, the compound represented by Formula 3, and the magnesium compound is prepared (Step 1).

The compound represented by Formula 2 may be 2,5-dibromo-3-hexylthiophene, 2-bromo-3-hexyl-5-iodothiophene, 3-hexylthiophene.

The compound represented by Formula 3 may be 2,5-dibromo-thiophene, 2-bromo-5-iodothiophen, or the like, preferably 2,5-dibromo-thiophene .

The magnesium compound may be isopropyl magnesium chloride, isopropyl magnesium bromide, tert-butyl magnesium chloride, tert-butyl magnesium bromide, or the like, preferably isopropyl magnesium chloride.

The solvent of the solution of step 1 may be tetrahydrofuran, chloroform, dichloromethane, chlorobenzene, dichlorobenzene, trichlorobenzene, toluene, p-xylene, etc., preferably tetrahydrofuran .

Finally, a polymerization initiator is added to the solution to prepare a copolymer (Step 2).

The polymerization initiator may be selected from the group consisting of Ni (dppp) Cl ₂ (1,3-bis (diphenylphosphino) propane) nickel, Ni (dppe) Cl ₂ dppf) Cl ₂ (1,3-bis (diphenylphosphino) ferrocene) nickel), and preferably Ni (dppp) Cl ₂ .

Hereinafter, the transistor including the copolymer of the present invention will be described.

The transistor includes a gate electrode formed on a substrate, a gate insulating film insulated from the gate electrode, a semiconductor layer formed on the gate insulating film, and a source electrode and a drain electrode, wherein the semiconductor layer is formed between the source electrode and the drain electrode Or the source electrode and the drain electrode may be located on the semiconductor layer, and the semiconductor layer may include the copolymer.

The crystals of the copolymer contained in the transistor may have strong π-π stacking to improve the charge mobility. The π-π stacking is not formed only in the crystal region of the copolymer crystal, and even if the crystallinity is decreased regardless of the crystallinity, inter-chain π-π stacking can be formed in the amorphous region.

The copolymer may include a copolymer in which the main chain of the copolymer is oriented in the horizontal direction with the surface of the gate insulating film, that is, a face-on oriented copolymer. The face-on orientation is an orientation in which the main chain is formed in the horizontal direction with respect to the plane direction of the substrate, and may be advantageous in charge transfer in the direction perpendicular to the substrate surface direction. On the contrary, the edge-on orientation is an orientation in which the main chain is formed in a direction perpendicular to the plane direction of the substrate, and can be advantageous in the charge transfer in the horizontal direction with respect to the plane direction of the substrate.

The crystals of the copolymer can be oriented face-on and edge-on, and preferably can be oriented face-on. However, the main chain of the copolymer does not necessarily have any one orientation. For example, the crystalline region of the copolymer may have an edge-on orientation, and the amorphous region may have a face-on orientation.

The source / drain electrodes may be formed of Au, Al, Ag, Be, Bi, Co, Cu, Cr, Hf, In, Mn, Mo, Mg, Ni, Nb, Pb, Pd, Pt, , Sb, Ta, Te, Ti, V, W, Zr, and Zn.

Hereinafter, the orientation method of the copolymer main chain of the present invention will be described.

First, a copolymer represented by the following formula (1) is prepared (step a).

[Chemical Formula 1]

In formula (1)

R is a C3 to C20 linear or branched alkyl group,

n and m are the number of repeating units,

The number average molecular weight is 3,000 to 500,000.

At this time, the orientation of the main chain of the copolymer can be controlled based on the plane direction of the substrate by controlling the ratio of n: m in the formula (1).

n: m may preferably be from 1:10 to 1: 1.5, more preferably from 1: 9 to 1: 1.7, even more preferably from 1: 8 to 1: 1.9.

Next, the copolymer is crystallized on the substrate to orient the main chain of the copolymer (step b).

Π-π stacking can be achieved by orienting the main chain of the copolymer, and the orientation of the copolymer crystals can be controlled according to the proportion of the repeating units of the regulated copolymer. Preferably, the crystal of the copolymer may have a face-on orientation with a high proportion of the main chain formed in the substrate in the horizontal direction.

The step (b) will be described in more detail. First, the copolymer is dissolved in a solvent to prepare a copolymer solution (step b-1).

The solvent may be tetrahydrofuran, chloroform, dichloromethane, chlorobenzene, dichlorobenzene, trichlorobenzene, toluene, p-xylene, or the like, preferably tetrahydrofuran.

Next, the copolymer solution is coated on the substrate (step b-2).

The coating may be spin coating, inkjet coating, dip coating, drop casting, bar coating, or the like, preferably spin coating .

Finally, the copolymer solution coated on the substrate is dried and crystallized to orient the main chain of the copolymer (step b-3).

The drying temperature in step b-3 may be 80 to 250 ° C, preferably 90 to 230 ° C, and more preferably 100 to 210 ° C.

[Example]

Hereinafter, preferred embodiments of the present invention will be described. However, this is for illustrative purposes only, and thus the scope of the present invention is not limited thereto.

Example 1: Preparation of Copolymer

Tetrahydrofuran (THF), in which isopropyl magnesium chloride (1.5 ml, 3 mmol) was placed in a globe box under nitrogen atmosphere, was added to 2,5-dibromo-3-hexylthiophene (815 mg, 2.5 mmol) Compound 1) and 2,5-dibromo-thiophene (121 mg, 0.5 mmol) (Compound 2) were dissolved in 20 ml of anhydrous tetrahydrofuran, and then stirred at room temperature for 1 hour. 5 ml of tetrahydrofuran in which Ni (dppp) Cl ₂ (12 mg, 0.023 mmol) was dispersed was added to initiate polymerization, and the mixture was stirred for 3 hours. The polymerization was quenched by the addition of 5N HCl. After precipitation in methanol, the polymer was then purified by soxhlet extraction in methanol, hexane and chloroform. The chloroform fraction was concentrated under reduced pressure. The concentrate was precipitated in methanol and filtered. The resulting polymer was dried in a vacuum oven at ambient temperature for 24 hours to give 341 mg of a copolymer which was a purple solid. (Yield, 75%)

GPC: M _n = 10,000, PDI = 1.08

^{1 H-NMR (400 MHz,} CDCl 3, ppm): δ 7.16-6.98 (br, 1H); 2.81 (t, J = 7.5 Hz, 1.33H); 1.71 (br, 1.33H); 1.36 (br, 4H); 0.91 (t, J = 6.6 Hz, 2H).

Example 2: Preparation of Copolymer

Instead of a solution of 2,5-dibromo-3-hexylthiophene (815 mg, 2.5 mmol) and 2,5-dibromo-thiophene (121 mg, 0.5 mmol) 3-yl) -hexylthiophene (734mg, 2.25mmol) and 2,5-dibromo-thiophene (182mg, 0.75mmol) in dichloromethane ≪ / RTI > (Yield: 72%)

GPC: M _n = 9,000, PDI = 1.09

^{1 H-NMR (400 MHz,} CDCl 3, ppm): δ 7.16-6.98 (br, 1H); 2.81 (t, J = 7.5 Hz, 1. 12 H); 1.71 (br, 1. 12H); 1.36 (br, 3.36H); 0.91 (t, J = 6.6 Hz, 1.68H).

Example 3: Preparation of copolymer

Instead of a solution of 2,5-dibromo-3-hexylthiophene (815 mg, 2.5 mmol) and 2,5-dibromo-thiophene (121 mg, 0.5 mmol) (815 mg, 2 mmol) and 2,5-dibromo-thiophene (242 mg, 1 mmol) was used in place of the compound obtained in Example 1, 255 mg of a copolymer which was a purple solid was obtained . (Yield: 62%)

GPC: M _n = 11,000, PDI = 1.26

^{1 H-NMR (400 MHz,} CDCl 3, ppm): δ 7.16-6.98 (br, 1H); 2.81 (t, J = 7.5 Hz, 1 H); 1.71 (br, 1 H); 1.36 (br, 3H); 0.91 (t, J = 6.6 Hz, 1.49H).

Example 4: Preparation of copolymer thin film (orientation of copolymer crystals) (RP20)

The opaque silicon wafer (boron-doped silicon, Siltron, Inc.) was washed with detergent, deionized water, ethanol and acetone for 15 minutes each and dried. 0.2 mg of the copolymer prepared according to Example 1 was dissolved in 100 μl of chloroform and spin-coated on a 1.5 × 1.5 mm silicon wafer at 1000 rpm. The copolymer thin film thus obtained was annealed at 100 ° C for 30 minutes to prepare a copolymer thin film.

Example 5: Preparation of copolymer thin film (orientation of copolymer crystals) (RP25)

A copolymer thin film was prepared in the same manner as in Example 4, except that the copolymer prepared in Example 2 was used in place of the copolymer prepared in Example 1.

Example 6: Preparation of copolymer thin film (orientation of copolymer crystals) (RP33)

A copolymer thin film was prepared in the same manner as in Example 4, except that the copolymer prepared in Example 3 was used in place of the copolymer prepared in Example 1.

Comparative Example 1: Preparation of poly (3-hexylthiophene) (P3HT)

Isopropylmagnesium chloride (0.5 ml, 1 mmol) in tetrahydrofuran (THF) was added to 20 ml anhydrous tetrahydrofuran in a globe box under a nitrogen atmosphere, to which was added 2,5-dibromo-3-hexylthiophene , 1 mmol) was added to the solution, and the mixture was stirred at room temperature for 1 hour. The polymerization was initiated with Ni (dppp) Cl ₂ (4.5 mg, 0.0083 mmol) dispersed in 5 ml of tetrahydrofuran and the mixture was stirred for 3 hours. The polymerization was terminated by the addition of 5N HCl. After precipitation in methanol, the polymer was then purified by soxhlet extraction in methanol, hexane and chloroform. The chloroform fraction was concentrated under reduced pressure. The concentrate was precipitated in methanol and filtered. The resulting polymer was dried in a vacuum oven at ambient temperature for 24 hours to give 120 mg of P3HT as a purple solid. (Yield, 72%)

GPC: M _n = 11,000, PDI = 1.06

^{1 H-NMR (400 MHz,} CDCl 3, ppm): δ 6.98 (s, 1H); 2.81 (t, J = 7.5 Hz, 2H); 1.71 (br, 2 H); 1.36 (br, 6 H); 0.91 (t, J = 6.6 Hz, 3 H).

Comparative Example 2: Preparation of P3HT thin film (orientation of P3HT crystal)

The opaque silicon wafer (boron-doped silicon, Siltron, Inc.) was washed with detergent, deionized water, ethanol and acetone for 15 minutes each and dried. 0.2 mg of the copolymer prepared according to Comparative Example 1 was dissolved in 100 mu l of chloroform and spin-coated on a 1.5 x 1.5 mm silicon wafer at 1000 rpm. The resulting thin film of the copolymer was annealed at 200 ° C for 30 minutes to prepare a P3HT thin film.

Device Embodiment 1: Fabrication of transistor

(70 nm) was formed on the thin film of the copolymer prepared according to Example 4 by thermal evaporation through a shadow mask having a channel length and a width of 150 and 1,500 μm, respectively, to form a source / .

Device Embodiment 2: Fabrication of transistor

A transistor was fabricated in the same manner as in Example 1 except that the copolymer thin film prepared in Example 5 was used instead of the copolymer prepared in Example 4.

Device Embodiment 3: Fabrication of transistor

A transistor was fabricated in the same manner as in Example 1 except that the copolymer thin film prepared in Example 6 was used instead of the copolymer prepared in Example 4.

Device comparison example 1: Fabrication of transistor

A transistor was fabricated in the same manner as in Example 1 except that the P3HT thin film prepared according to Comparative Example 2 was used in place of the copolymer prepared according to Example 1.

[Test Example]

Test Example 1: Synthesis and Characterization of Copolymer

FIG. 1 is a nuclear magnetic resonance (NMR) spectrum of a polymer prepared according to Examples 1 to 3 and Comparative Example 1, and Table 1 shows molecular weights (Mn) and molecular weight distributions measured by gel permeation chromatography (GPC) ).

Referring to Figure 1, broad peaks in the range of 6.98-7.15 ppm of the copolymers prepared according to Examples 1 to 3 occur from aromatic hydrogens of 3-hexylthiophene and thiophene units , And in particular 6.98 ppm peak, are due to the aromatic proton of head-to-tail-head-to-tail (HT-HT) triads. On the other hand, wide peaks in the range of 7.00-7.15 ppm correspond to head-to-head-to-head (HH-TH) triads and tail- And is derived from regioirregular aromatic protons such as tail-to-tail-head-to-head (TT-HH) triads. Therefore, the width of the aromatic hydrogen peak is considered to mean that the two repeating units are randomly distributed along the main chain of the copolymer depending on the molar ratio of the repeating units. If a block copolymer was formed, there would be fewer, sharp peaks in the NMR spectrum.

Referring to Table 1, the molecular weights of all polymers were similar, but the molecular weight distribution (PDI) slightly increased with the amount of thiophene unit. This is because the solubility of the polymer is reduced due to the thiophene unit having no alkyl side chain.

Thus, the copolymers prepared according to Examples 1 to 3 are random copolymers and all of the polymers have similar molecular weights, and the effect of molecular weight on the formation of self-assembled structures and optoelectronic properties It can be minimized.

division Ratio of feed molar amount of raw material
(2,5-dibromo-3-hexylthiophene: 2,5-dibromo-thiophene) The ratio of repeating units
(3-hexylthiophene: thiophene) Mn
(g / mol) PDI Comparative Example 1 - - 11,000 1.06 Example 1 5: 1 1: 0.2 10,000 1.07 Example 2 3: 1 1: 0.25 9,000 1.17 Example 3 2: 1 1: 0.33 11,000 1.26

Test Example 2: Determination of polymer crystallinity

FIG. 2 shows DSC (differential scanning calorimetry) analysis results of the polymer thin films prepared according to Examples 4 to 6 and Comparative Example 2. FIG.

Referring to FIG. 2, the melting temperature (T _m ) of the comparative example 2 (P3HT) was 218 ° C and the recrystallization temperature (T _c ) was 188 ° C. Example 4. The melting temperature (T _m) of (RP20) is 171 ℃, re-crystallization temperature (T _c) is the melting temperature (T _m) is 147 ℃, re-crystallization temperature of 137 ℃, and Example 5 (RP25) (T _c (T _m ) of 123 占 폚 and the recrystallization temperature (T _c ) of 92 占 폚 of Example 6 (RP33), and the copolymer prepared according to Examples 4 to 6 had a thiophene unit As the amount increased, the melting temperature (T _m ) and recrystallization temperature (T _c ) gradually decreased.

Therefore, since the decrease of the melting temperature (T _m ) and the recrystallization temperature (T _c ) shows that the crystallinity of the copolymer decreases, the copolymer thin film prepared according to Examples 4 to 6 And the crystallinity of the catalyst was decreased.

Test Example 3: Increase and orientation of π-π stacking of polymer

Fig. 3 shows the results of UV-vis absorption spectrum analysis of the polymer thin films prepared according to Examples 4 to 6 and Comparative Example 2 before and after annealing, Fig. 4 shows the results of X-ray scattering pattern measurement, Are shown in Table 2 below. FIG. 5 shows the NEXAFS (near-edge X-ray absorption fine structure) analysis results of the polymer thin films prepared according to Example 6 and Comparative Example 2. FIG.

Referring to FIG. 3, the UV-vis absorption spectra of the polymers prepared according to Examples 4 to 6 and Comparative Example 2 were almost similar, but they differed at a shoulder peak near 590 nm. The shoulder peak is due to the difference in the degree of pi-pi stacking depending on the molar ratio of 3-hexylthiophene to thiophene unit in the backbone. In the case of Comparative Example 2 (P3HT), the smallest π-π shoulder peak was shown, whereas in Example 3 (RP20) to Example 6 (RP33), the larger the amount of thiophene unit was, Respectively.

Therefore, it can be seen that π-π stacking is not related to crystallinity, and π-π stacking is derived from an amorphous region rather than a crystalline domain of the polymer.

Referring to FIG. 4 and Table 2, as the density of the alkyl side chain was decreased from Comparative Example 2 (P3HT) to Example 4 (RP33), the (100) plane d- spacing of the polymer was 16.6 Å (P3HT) (RP33), and the interplanar distance of π-π plane also decreased from 3.76 Å (P3HT) to 3.66 Å (RP33), indicating a decrease in crystallinity. However, even if the intensity of the (100) peak having the face-on orientation is lower than that of the comparative example 2 (P3HT) as shown in FIG. 4C, Lt; RTI ID = 0.0 > pi-pi < / RTI > stacking strength.

Therefore, it is expected that the π-π stacking increases in the non-planar direction even when the crystallinity decreases, and the charge transfer characteristic of the copolymer crystal is improved through strong π-π stacking.

Referring to FIG. 5, Comparative Example 2 (P3HT) exhibited angular dependence at edge-on (R = 0.26) and Example 6 (RP33) had face-on (R = -0.25) angular dependence . This is in contrast to the above XRD analysis results that most of the crystal regions of Example 6 (RP33) appeared to have an edge-on orientation. This means that the large number of amorphous chains of Example 6 (RP33) has a face-on orientation. In other words, the amorphous chains of the face-on orientation resulting from the reduced structural regularity of the chains provide a rather well-connected charge carrier transport pathway.

Thus, it was found that the phase-on orientation due to the amorphous chain regions of the copolymer thin films prepared according to Examples 4 to 6 formed strong? -Π stacking and provided charge carrier movement paths.

division Out-of-plane direction In an in-plane direction, 100 [Å] π-π [Å] 100 [Å] π-π [Å] Comparative Example 2 15.7 3.71 16.6 3.76 Example 4 15.4 3.65 16.4 3.68 Example 5 15.0 3.60 16.0 3.66 Example 6 14.6 3.60 15.5 -

Test Example 4: Measurement of charge carrier mobility of a transistor

6 shows the results of measurement of the charge carrier mobility of the transistors manufactured according to the device embodiments 1 to 3 and the device comparison example 1, and Table 3 shows the values thereof.

Referring to FIG. 6 and Table 3, as the density of the alkyl side chain of the polymer included in the transistor is lowered from the device comparison example 1 (P3HT) to the device example 3 (RP33), the charge carrier mobility is 0.27 cm ² / Vs (P3HT) to 1.34 cm < ² > / Vs (RP33).

Thus, although the crystallinity of the copolymers included in the transistors fabricated according to the device embodiments 1 to 3 is reduced, the strong? -Stacking formed by the phase-on orientation of the chains in the amorphous region causes the charge carrier migration path .

division Mobility
[cm ² / Vs] Device Comparative Example 1 (P3HT) 0.27 Device Example 1 (RP20) 0.84 Device Example 2 (RP25) 1.04 Device Example 3 (RP33) 1.34

The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

Claims (20)

(a) polymerizing a compound represented by the following formula (2) and a compound represented by the following formula (3) to prepare a copolymer represented by the following formula (1); And
(b) crystallizing the copolymer on the substrate to orient the main chain of the copolymer, and
Wherein the ratio of n: m in the formula (1) is controlled to adjust the orientation of the main chain of the copolymer based on the plane direction of the substrate.
[Chemical Formula 1]

In formula (1)
R is a C3 to C20 linear or branched alkyl group,
n and m are the number of repeating units,
The number average molecular weight is 3,000 to 500,000.
(2)

In formula (2)
R is a C3 to C20 linear or branched alkyl group,
X ¹ and X ² are the same as or different from each other, and X ¹ and X ² are each independently a halogen atom.
(3)

In formula (3)
X ³ and X ⁴ are the same as or different from each other, and each of X ³ and X ⁴ is independently a halogen atom. The method according to claim 1,
Wherein R is a linear alkyl group having from 3 to 10 carbon atoms. 3. The method of claim 2,
Wherein R is a hexyl group. delete The method of claim 1, wherein step (a)
(1) preparing a solution containing a compound represented by Formula 2, a compound represented by Formula 3, and a magnesium compound; And
(2) adding a polymerization initiator to the solution to prepare a copolymer;
≪ / RTI > wherein the copolymer is present in an amount of less than 50% by weight. The method according to claim 1,
Wherein R is a linear alkyl group having from 3 to 10 carbon atoms. 6. The method of claim 5,
Wherein the magnesium compound comprises at least one selected from the group consisting of isopropyl magnesium chloride, isopropyl magnesium bromide, tert-butyl magnesium chloride, and tertiary-butyl magnesium bromide. 6. The method of claim 5,
Wherein the polymerization initiator comprises at least one selected from Ni (dppp) Cl ₂ , Ni (dppe) Cl ₂ , and Ni (dppf) Cl ₂ . delete delete delete delete delete delete delete The method according to claim 1,
and n: m is from 1:10 to 1: 1.5. The method according to claim 1,
Step (b)
(b-1) dissolving the copolymer in an organic solvent to prepare a copolymer solution;
(b-2) coating the copolymer solution on a substrate; And
(b-3) drying and crystallizing the copolymer solution coated on the substrate to orient the main chain of the copolymer;
≪ / RTI > wherein the copolymer is present in an amount of less than 50% by weight. 18. The method of claim 17,
Characterized in that the solvent comprises at least one selected from the group consisting of tetrahydrofuran, chloroform, dichloromethane, chlorobenzene, dichlorobenzene, trichlorobenzene, toluene, and p-xylene. . 18. The method of claim 17,
In the step (b-2), a method of coating the copolymer solution on a substrate may be a spin coating method, an inkjet coating method, a dip coating method, a drop casting method and a bar coating method bar coating. < RTI ID = 0.0 > 21. < / RTI > 18. The method of claim 17,
Wherein the drying temperature is 80 ° C to 250 ° C.

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