KR20080018595A - Organic thin film transistor using alternating copolymers of phenylene vinylene and arylene vinylene and preparation method thereof - Google Patents

Abstract

An organic thin film transistor using alternative copolymer of phenylene vinylene and arylene vinylene and a manufacturing method thereof are provided to maintain a leakage current low and obtain a high current on/off ratio and charge mobility. An organic thin film transistor includes a substrate(1), a gate electrode(2), a gate insulating layer(3), an organic active layer(6) and source/drain electrodes(4,5). The active layer is made of alternative copolymer of phenylene vinylene and arylene vinylene. The gate electrode and the source/drain electrodes are made of any one selected from the group consisting of Au, Ag, Al, Ni, Cr and indium tin oxide.

Description

Organic thin film transistor using alternating copolymers of phenylene vinylene and arylene vinylene and preparation method

1 is a schematic cross-sectional view of an organic thin film transistor element according to an embodiment of the present invention;

2 is a ¹ H-NMR spectrum of an alternating copolymer (PPVTV-1) of a phenylene vinylene (PV) derivative and thienylene vinylene (TV) obtained in Preparation Example 1;

3 is a UV-VIS Spectra of the PPVTV-3 film obtained in Preparation Example 2,

4 is a ¹ H-NMR spectrum of an alternating copolymer (PPVPV-1) of phenylene vinylene derivative (PV) and phenylene vinylene (PV) obtained in Preparation Example 3;

5 is a current transfer characteristic curve of PPVTV-1 obtained in Example 1, and

6 is a current transfer characteristic curve of PPVTV-3 obtained in Example 2. FIG.

<Description of the symbols for the main parts of the drawings>

1: substrate, 2: gate electrode,

3: gate insulating layer, 4: source electrode,

5: drain electrode, 6: organic active layer

The present invention relates to an organic thin film transistor using an alternating copolymer of phenylene vinylene and arylene vinylene, and more particularly, to a substrate, a gate electrode, a gate insulating layer, an organic active layer, and a source / drain electrode. An organic thin film transistor comprising: an organic active layer is formed of an phenylene vinylene and arylene vinylene alternating copolymer, and relates to an organic thin film transistor and a method of manufacturing the same.

An organic thin film transistor (OTFT) generally includes a substrate, a gate electrode, an insulating layer, a source / drain electrode, and a channel layer, and a bottom contact BC in which a channel layer is formed on the source and drain electrodes. ) And a top contact (TC) type in which a metal electrode is formed from behind, for example, by mask deposition on the channel layer.

Inorganic semiconductor materials such as silicon (Si) have been generally used as the channel layer of the thin film transistors, but in recent years, large-area, low-cost, and flexible displays have been used as inorganic semiconductor materials for high-cost, high-temperature vacuum processes. I'm changing.

Recently, many organic semiconductor materials for channel layers of organic thin film transistors (OTFTs) have been studied, and their transistor characteristics have been reported. The most studied low molecular or oligomeric organic semiconductor materials include melancyanine, phthalocyanine, perylene, pentacene, C60, thiophene oligomer, etc. An organic thin film transistor having a high charge mobility of Vs or more has been developed and reported (Mat. Res. Soc. Symp. Proc. 2003, Vol. 771, L6.5.1 to L6.5.11). However, the above-described prior art has increased manufacturing costs since the thin film formation mainly depends on the vacuum process.

On the other hand, many organic thin film transistors (OTFTs) using thiophene-based polymers have been reported as polymer materials. However, the characteristics of OTFTs using low-molecular materials cannot be reached, but low-cost large-area processing is possible by solution processing such as printing technology. It can be said that there is an advantage in processability. Cambridge University and Seiko Epson have already produced a polymer-based OTFT device employing a polythiophene-based material called F8T2 and reported a charge mobility of 0.01 to 0.02 cm 2 / Vs (International Publication WO 00/79617, Science, 2000). , vol. 290, pp. 2132-2126). As mentioned above, the organic semiconductor polymer material is inferior to the pentacene, which is a low molecular material material, such as charge mobility, but has the advantage that the TFT can be manufactured at low cost without requiring a high operating frequency.

However, in order to commercialize the OTFT, it is necessary to satisfy not only the charge mobility but also an important parameter such as a high on / off ratio. In order to do this, the leakage current in the off state should be reduced as much as possible. Today, various methods have been tried to improve these characteristics.

U.S. Patent No. 5,625,199 reports the result of slightly improving the parameters of OTFT devices by combining n-type inorganic semiconductor material and p-type organic semiconductor material as active layers, but the conventional silicon-based TFT process requiring deposition. It is not different from the mass production. US Pat. No. 6,107,117 fabricated an OTFT device having a charge mobility of 0.01 to 0.04 cm 2 / Vs using regioregular polythiophene (P3HT). However, in the case of the regioregular polythiophene P3HT, the charge mobility is about 0.01 cm 2 / Vs, but the blocking leakage current (10 ^-9 A or more) is high, so that the current flashing ratio is very low (400 or less). it's difficult.

As such, organic semiconductor polymers for high molecular weight organic thin film transistors that satisfy both high charge mobility and low leakage current are not reported.

The present invention is to solve the above problems of the prior art, one object of the present invention is to satisfy the high charge mobility and low leakage current (phenylene vinylene, PV) and arylene vinylene ( An organic thin film transistor using a p-type polymer derivative including an alternating copolymer of arylene vinylene (AV) as an organic active layer is provided.

Another object of the present invention is to provide a method for producing an organic thin film transistor using a polymer derivative comprising alternating phenylene vinylene and arylene vinylene.

One aspect of the present invention for achieving the above object is

In an organic thin film transistor including a substrate, a gate electrode, a gate insulating layer, an organic active layer, and a source / drain electrode, the organic active layer is formed of a phenylene vinylene-arylene vinylene alternating copolymer represented by Formula 1 below It relates to an organic thin film transistor characterized in that.

Wherein R ¹ and R ² are each independently hydrogen, a hydroxy group, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, alkoxyalkyl group having 1 to 20 carbon atoms, or a linear, branched or cyclic alkoxy group having 1 to 16 carbon atoms Gigi,

Ar is S, O or NR ⁵ An aryl group having 4 to 30 carbon atoms containing one hetero atom or not containing a hetero atom, wherein R ⁵ is each independently hydrogen, a hydroxy group, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, and 1 to C carbon atoms. 20 alkoxyalkyl groups, or linear, branched or cyclic alkoxy groups having 1 to 16 carbon atoms, and

n is an integer of # 4 to 200.

In the present invention, the phenylene vinylene-arylene vinylene alternating copolymer may be prepared by a Horner-Emmons reaction.

In another aspect, the present invention relates to an organic thin film transistor using an alternating copolymer of phenylene vinylene and arylene vinylene and a method of manufacturing the same.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The organic thin film transistor of the present invention includes a substrate, a gate electrode, a gate insulating layer, an organic active layer, and a source / drain electrode, wherein the organic active layer is a phenylene vinylene-arylene vinylene alternating copolymer represented by the following Chemical Formula 1 Characterized in that formed.

[Formula 1]

Wherein R ¹ and R ² are each independently hydrogen, a hydroxy group, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, alkoxyalkyl group having 1 to 20 carbon atoms, or a linear, branched or cyclic alkoxy group having 1 to 16 carbon atoms Gigi,

Ar is S, O or NR ⁵ An aryl group having 4 to 30 carbon atoms, including one hetero atom, or no hetero atom; wherein R ⁵ Are each independently hydrogen, a hydroxy group, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, an alkoxyalkyl group having 1 to 20 carbon atoms, or a linear, branched or cyclic alkoxy group having 1 to 16 carbon atoms, and

n is an integer of # 4 to 200.

In the polymer compound of Formula 1, phenylene vinylene and arylene vinylene are alternately included in the polymer main chain, and arylene vinylene including an aryl group which can be an electron donor in phenylene vinylene, which is one of the representative conductive polymers, It is a p-type polymer organic semiconductor with a new structure copolymerized alternately. Since the polymer organic semiconductor has an amorphous state in the film state and has excellent π-stacking property, when used as an organic active layer in an electronic device such as an organic thin film transistor, it maintains a low leakage state and at the same time high The current blink rate and charge mobility can be obtained.

The phenylene vinylene-arylene vinylene alternating copolymer represented by Formula 1 of the present invention may be prepared by copolymerizing monomers represented by the following Formulas 2 and 3.

Where

R ¹ and R ² are the same as defined in Formula 1,

Y is a C1-C4 alkyl group.

Where

X is S, O, or NR ⁵ and R ³ , R ⁴ and R ⁵ are each independently hydrogen, a hydroxy group, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, alkoxyalkyl group having 1 to 20 carbon atoms, or a linear, branched or cyclic alkoxy group having 1 to 16 carbon atoms It is not limited to this.

In the phenylene vinylene-arylene vinylene alternating copolymer represented by Chemical Formula 1, examples of Ar include compounds represented by the following Chemical Formula 4, but are not limited thereto.

Where

X is S, O, or NR ⁵ and R ³ , R ⁴ and R ⁵ are each independently hydrogen, a hydroxy group, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, alkoxyalkyl group having 1 to 20 carbon atoms, or a linear, branched or cyclic alkoxy group having 1 to 16 carbon atoms It is not limited to this.

In the present invention, the phenylene vinylene-arylene vinylene alternating copolymer may be polymerized by a Horner-Emmons reaction. By the above reaction, the dialkyl phosphoric acid is removed and acetylene which is a double bond is repeatedly generated between the phenylene derivative and the aryl derivative to obtain a phenylene vinylene-arylene vinylene alternating copolymer. In the reaction, sodium methoxide, potassium butoxide and the like are used as a reaction accelerator, and dimethyl formaldehyde (DMF), tetrahydrofuran (THF), N-methylpyrrolidinone (NMP) and the like may be used as a polymerization medium. .

An example of the polymerization reaction of the phenylene vinylene-arylene vinylene alternating copolymer of the present invention using the monomers represented by Formulas 2 and 3 is shown in Scheme 1 and Scheme 2.

In Scheme 1,

n is an integer of # 20 to 100.

The number average molecular weight of the alternating copolymers of phenylene vinylene and arylene vinylene (thienylene vinylene) obtained by the above Scheme 1 is approximately 20,000 to 100,000, and the number average molecular weight of the preferred copolymer of the present invention is 20,000 or more. to be.

In Scheme 2,

n is an integer of 4 to 100.

The number average molecular weight of the alternating copolymer of phenylene vinylene and arylene vinylene (phenylene vinylene) obtained by the above Reaction Scheme 2 is 10,000 to 100,000, and the number average molecular weight of the preferred copolymer of the present invention is 10,000 or more. .

In the present invention, an alternating copolymer of phenylene vinylene and arylene vinylene which can be synthesized by the Honer-Emmons reaction represented by Schemes 1 and 2 may be a compound represented by the following Chemical Formula 5, but is not limited thereto. Do not.

Wherein n is an integer of # 4 to 200.

The alternating copolymer derivatives of phenylene vinylene and arylene vinylene of the present invention are used as core materials such as charge generation and moving layers in electronic devices such as photovoltaic devices, organic light emitting devices (LEDs) and sensors. It may be, but is not limited thereto.

In addition, the alternating copolymer derivatives of phenylene vinylene and arylene vinylene of the present invention can be used as new organic semiconductor materials to prepare the active layers of organic thin film transistors (OTFTs). In this case, the organic active layer may be formed by screen printing, printing, spin coating, dipping, or ink spray, but is not limited thereto.

The OTFT device has a structure of a substrate / gate electrode / gate insulating layer / active layer / source-drain electrode, which is commonly known as shown in FIG. 1, or a structure of a substrate / gate electrode / gate insulating layer / source-drain electrode / active layer, or the like. It may be formed as, but is not limited thereto.

The OTFT can be used for the large dielectric constant is used as in a conventional gate insulating layer constituting the insulator element, specifically a _{Ba 0 .33 Sr 0 .66 TiO 3} (BST), Al 2 O 3, Ta 2 O 5 _{, La 2 O 5, Y 2} O 3 and a ferroelectric insulator, PbZr _{0 .33} selected from the group consisting of _{TiO 2 Ti 0 .66 O 3 (} PZT), Bi 4 Ti 3 O 12, BaMgF 4, SrBi 2 (TaNb) Inorganic insulators selected from the group consisting of ₂ O ₉ , Ba (ZrTi) O ₃ (BZT), BaTiO ₃ , SrTiO ₃ , Bi ₄ Ti ₃ O ₁₂ , SiO ₂ , SiN _x and AlON, or polyimide, BCB Organic insulators such as benzocyclobutene, parylene, polyacrylate, polyvinylalcohol, and polyvinylphenol may be used, but are not limited thereto.

In addition, as the gate, source, and drain electrodes constituting the OTFT device, a metal commonly used may be used. Specifically, gold (Au), silver (Ag), aluminum (Al), and nickel (Ni) indium tin oxide ( ITO) and the like, but is not limited thereto.

In addition, the substrate materials constituting the OTFT device may include glass, polyethylenenaphthalate (PEN), polyethyleneterephthalate (PET), polycarbonate, polyvinylalcohol, and polyacrylate. , Polyimide or polynorbornene, polyethersulfone (PES), etc. may be used, but is not limited thereto.

Hereinafter, although this invention is demonstrated concretely based on an Example, these are only for the purpose of description, and the protection scope of this invention is not limited to these.

Production Example  One : Phenylene Vinylene (PV) derivatives   Thienylene Of vinylene (TV) Alternating copolymer  Synthesis of (PPVTV-1)

PV derivative in flask (R ¹ , R ² in Formula ²⁾ = -OC ₈ H ₁₇ , 10 mmol) and 2,5-dicarboxaldehyde thiophene (R ³ , R ⁴ in Formula 3) = H, X = S 10 mmol) THF solution of 30 mmol of 1M t-BuOK (t-butoxylate) in 50 mL of tetrahydrofuran (THF) was slowly added and heated to 70 degrees. After the reaction for 12 hours, the mixture was reprecipitated in methanol, recovered, and dried to obtain a polymer PPVTV-1 (yield: 50%, number average molecular weight = 17,000). The ¹ H-NMR spectral curve of the obtained chloroform solution of PPVTV-1 is shown in FIG. 2.

Production Example  2 : Phenylene Vinylene (PV) derivatives   Thienylene Of vinylene (TV) Alternating copolymer  Synthesis of (PPVTV-3)

PV derivatives (R ¹ , R ² in Formula ²⁾ = -OC ₁₂ H ₂₅ , 10 mmol) was synthesized in the same manner as in Preparation Example 1 except that the alternating copolymer (PPVPV-3) (yield: 91%, number average molecular weight = 25,000). The UV-VIS spectrum curve of the obtained PPVPV-3 film is shown in FIG. 3.

Production Example  3: Phenylene Vinylene (PV) derivatives   Phenylene Vinylene (PV) Alternating copolymer  Synthesis of (PPVPV-1)

PV derivatives (R ¹ , R ² in Formula ²⁾ = -OC ₁₂ H ₂₅ , 10 mmol) and dicarbaaldehyde phenyl compound (R ³ in Formula ³⁾ , R ⁴ An alternating copolymer (PPVPV-1) was synthesized in the same manner as in Preparation Example 1 except for using H, 10 mmol) as a monomer (yield: 81%, number average molecular weight = 21,000). The ¹ H-NMR spectral curve of the obtained chloroform solution of PPVPV-1 is shown in FIG. 4.

Example  One : [ PV With derivatives TV of Alternating copolymer ] PPVTV Manufacture of Organic Thin Film Transistor Using

First, 1000 크롬 of chromium used as a gate electrode was deposited on the cleaned glass substrate by sputtering, and then SiO ₂ used as a gate insulating film was deposited to 1000 Å by CVD.

ITO used as a source-drain electrode was deposited to 1200 micrometers thickness by the sputtering method on it. The substrate was washed with 10 minutes using isopropyl alcohol and then dried and used before depositing the organic semiconductor material.

ITO was immersed in octaformyltrichlorosilane solution diluted to 10 mM concentration in chloroform for 30 seconds, washed with acetone and dried, and then phenylene vinylene (PV) derivative synthesized in Preparation Example 1 and thienylene vinylene. The alternating copolymer PPVTV-1 of (TV) was dissolved in chloroform at a concentration of 1 wt%, coated at 1000 rpm at 1000 rpm, and baked at 100 ° C. for 1 hour in an argon atmosphere to prepare an OTFT device.

Example  2 : PPVTV Manufacture of Organic Thin Film Transistor Using

In the present embodiment, an organic thin film transistor device was manufactured in the same manner as in Example 1, except that PPVTV-3 was used.

Example  3: PPVPV - 1  Fabrication of Used Organic Thin Film Transistors

In the present embodiment, an organic thin film transistor device was manufactured in the same manner as in Example 1, except that PPVPV-1 was used.

Comparative Example 1: Fabrication of Organic Thin Film Transistor Using P3HT

This Comparative Example was prepared in the same manner as in Example 1 except for using P3HT (poly (3-hexylthiophene)) instead of using the alternating copolymer PPVTV-1 in Example 1.

After measuring current transfer characteristic curves using the KEITHLEY Semiconductor Characterization System (4200-SCS) for the devices manufactured by Examples 1 to 3 and Comparative Example 1, the electrical characteristics are shown in Table 1 .

TABLE 1

The charge mobility was obtained from (S _SD ) ^1/2 and V _G as variables from the saturation region current equation and obtained from the slope.

Where I _SD is the source-drain current, μ or μ _FET is the charge mobility, C _o is the oxide capacitance, W is the channel width, L is the channel length, V _G is the gate voltage, V _T is the threshold voltage

The cutoff leakage current (I _off ) is a current flowing in the off state, and is determined as the minimum current in the off state from the current ratio.

The current blink ratio (I _on / I _off ) was obtained by the ratio of the maximum current value in the on state and the minimum current value in the off state.

As can be seen in Table 1, the alternating copolymer derivatives of the phenylene vinylene and arylene vinylene of Examples 1 and 2 significantly lower the leakage current in the off state of the OTFT, and the current flickers. The rain increased.

As described above, the alternating copolymer derivative of phenylene vinylene and arylene vinylene of the present invention is a p-type polymer organic semiconductor having a novel structure, which is excellent in stability with low leakage current and high charge mobility and can be provided as an active layer for OTFT devices. .

Claims (9)

In an organic thin film transistor including a substrate, a gate electrode, a gate insulating layer, an organic active layer, and a source / drain electrode, the organic active layer is a phenylene vinylene-arylene vinylene alternating copolymer represented by Formula 1 below. An organic thin film transistor, characterized in that formed. [Formula 1]

Wherein R ¹ and R ² are each independently hydrogen, a hydroxy group, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, alkoxyalkyl group having 1 to 20 carbon atoms, or a linear, branched or cyclic alkoxy group having 1 to 16 carbon atoms Gigi, Ar is S, O or NR ⁵ An aryl group having 4 to 30 carbon atoms, including one hetero atom, or no hetero atom; wherein R ⁵ Are each independently hydrogen, a hydroxy group, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, an alkoxyalkyl group having 1 to 20 carbon atoms, or a linear, branched or cyclic alkoxy group having 1 to 16 carbon atoms, and n is an integer of # 4 to 200. The organic thin film transistor according to claim 1, wherein the phenylene vinylene-arylene vinylene copolymer is copolymerized with a monomer represented by the following Chemical Formulas 2 and 3.  [Formula 2]

Wherein R ¹ and R ² are each independently hydrogen, a hydroxy group, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, alkoxyalkyl group having 1 to 20 carbon atoms, or a linear, branched or cyclic alkoxy group having 1 to 16 carbon atoms Gigi, Y is a C1-C4 alkyl group. [Formula 3]

Wherein X is S, O, or NR ⁵ , and R ³ to R ⁵ are each independently hydrogen, a hydroxy group, a linear or branched alkyl group having 1 to 20 carbon atoms, an alkoxyalkyl group having 1 to 20 carbon atoms, or carbon atoms 1 to 16 linear, branched or cyclic alkoxy groups. The organic thin film transistor of claim 1, wherein Ar is selected from a compound represented by Formula 4 below. [Formula 4]

Wherein X is S, O, or NR ⁵ , and R ³ , R ⁴ and R ⁵ are each independently hydrogen, a hydroxy group, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, alkoxyalkyl group having 1 to 20 carbon atoms, or a linear, branched or cyclic alkoxy group having 1 to 16 carbon atoms . The organic thin film transistor according to claim 1, wherein the alternating copolymer of phenylene vinylene-arylene vinylene is selected from compounds represented by the following formula (5). [Formula 5]

Wherein n is an integer of 4 to 200 The method of claim 1, wherein the gate insulating layer is a _{Ba 0 .33 Sr 0 .66 TiO 3} (BST), Al 2 O 3, Ta 2 O 5, La 2 O 5, Y 2 O 3 , and the group consisting of TiO ₂ Ferroelectric insulators selected from PbZr _0.33 Ti _0.66 O ₃ (PZT), Bi ₄ Ti ₃ O ₁₂ , BaMgF ₄ , SrBi ₂ (TaNb) ₂ O ₉ , Ba (ZrTi) O ₃ (BZT), BaTiO ₃ , SrTiO ₃ , Inorganic insulators selected from the group consisting of Bi ₄ Ti ₃ O ₁₂ , SiO ₂ , SiN _x and AlON, or polyimide, BCB (benzocyclobutene), parylene, polyacrylate, polyvinyl alcohol An organic thin film transistor, characterized in that formed of an organic insulator selected from the group consisting of Polyvinylalcohol and Polyvinylphenol. The method of claim 1, wherein the substrate is glass, polyethylenenaphthalate (PEN), polyethylene terephthalate (PET), polycarbonate, polyvinyl alcohol, polyacrylate, polyacrylate An organic thin film transistor, characterized in that formed of a material selected from the group consisting of polyimide, polynorbornene, and polyethersulfone (PES). The method of claim 1, wherein the gate electrode and the source-drain electrode are selected from the group consisting of gold (Au), silver (Ag), aluminum (Al), nickel (Ni), chromium (Cr), and indium tin oxide (ITO). An organic thin film transistor, characterized in that formed of a selected material. In an organic thin film transistor including a substrate, a gate electrode, a gate insulating layer, an organic active layer, and a source / drain electrode, the organic active layer is a phenylene vinylene-arylene vinylene alternating copolymer represented by Formula 1 Method for manufacturing an organic transistor device, characterized in that formed. The method of claim 8, wherein the organic active layer is formed into a thin film by screen printing, printing, spin coating, dipping, or ink spraying.

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