KR101933102B1 - Organic thin-film transistor array comprising organic thin-film transistor using ambipolar polymer semiconductor for solution process and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a bipolar polymer semiconductor compound represented by structural formula 1. The compound is excellent in water repellency and chemical resistance, and has an excellent effect of forming thin films. The bipolar polymer semiconductor material suitable for a photolithography process can be used to realize a fine pattern and realize a large area chemical sensor. In addition, a device manufactured using the bipolar polymer semiconductor has an effect of increasing the balance of electron and hole mobility and having excellent performance. In structural formula 1, R_1 to R_14 are the same or different from each other and each of R_1 to R_14 is independently a linear or branched alkyl group of C1 to C20.

Description

TECHNICAL FIELD The present invention relates to an organic thin film transistor array including an organic thin film transistor using a bipolar polymer semiconductor for solution process, and an organic thin film transistor array including the organic thin film transistor array using a bipolar polymer semiconductor for solution process,

The present invention relates to a polymer semiconductor for a solution process, a method of manufacturing the same, and an organic transistor including the polymer semiconductor, and more particularly, to a polymer semiconductor for a solution process which is applicable to a photolithography process and has excellent chemical resistance, And a method of manufacturing an organic transistor array.

Polymer semiconductors are a next-generation electronic material that can replace the current silicon-based electronics industry because of its ability to process solutions, high mechanical flexibility, and the ability to control electrical properties through alteration of molecular structures. I have received. In particular, ambipolar polymer semiconductors capable of transporting both holes and electrons are important materials in the fabrication of logic circuits based on organic electronic materials, and various related researches have been actively conducted.

Graphene is one of the carbon isotopes and is a structure in which carbon atoms gather to form a two-dimensional plane. It is composed of one atom (0.2 nm) thick and has high physical and chemical stability. It conducts electricity 100 times more than copper and moves electrons more than 100 times faster than monocrystalline silicon, which is mainly used as a semiconductor. It has excellent elasticity and can be used for transparent flexible electrodes because it has properties that it does not lose its electrical properties even when it is stretched or bent, and it is called 'dream nanomaterial' with this characteristic.

Photolithography is a process for forming a pattern designed on a mask on a wafer. It is the most important process in the manufacturing process of semiconductors. It is a technology to copy the shadows generated by applying light to a disc called mask, which is made of a metal pattern on a glass plate, on a desired circuit design.

Since bipolar polymer semiconductors are polymer semiconductors that can utilize both holes and electrons as driving holes, it is possible to simplify the manufacturing process and maximize the device stability in pn junction and complementary circuit manufacturing. Therefore, bipolar polymer semiconductor technology is the key development technology of next generation electronic devices .

Polymer semiconductors are significantly lower in performance when exposed to various chemicals due to their low chemical stability compared to silicon materials, and thus they have a limitation in that a large area patterning process typified by a photolithography process is impossible, This is the biggest problem to prevent the commercialization of the device.

A bipolar polymer semiconductor transistor can cause both holes and electrons to flow through the current. However, the performance of the bipolar polymer semiconductor transistor is significantly lower than that of the hole transporting ability. The larger the difference is, the lower the utilization value of the device. In order to overcome this problem, a material having a small difference between the energy level of the semiconductor layer and the work function of the electrode is required.

The problems of the prior arts lead to deterioration of the productivity, reliability, and economical efficiency of the polymer semiconductor device, and it is difficult to apply the bipolar polymer semiconductor to the organic electronic material and commercialize it.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems described above and provide a bipolar polymer semiconductor material having excellent water repellency and chemical resistance and containing siloxane groups excellent in thin film formation characteristics.

Also, a large area organic transistor and a chemical sensor, which realize a fine pattern using a bipolar polymer semiconductor material suitable for a photolithography process, are provided.

According to an aspect of the present invention, there is provided a bipolar polymer semiconductor compound represented by the following structural formula (1).

[Structural formula 1]

In the above formula 1,

R ₁ to R ₁₄ are the same or different from each other, and R ₁ to R ₁₄ are independently of each other a C ₁ to C 20 linear or branched alkyl group,

X ₁ to X ₆ are the same or different, and each of X ₁ to X ₆ is independently one of the group 16 atoms,

m and n are the same or different from each other, m and n are each independently an integer of 1 to 15,

p is the number of repeating units,

The number average molecular weight is from 5,000 to 1,000,000.

R ₁ to R ₁₄ are the same as or different from each other, and R ₁ to R ₁₄ may be independently selected from a methyl group and an ethyl group.

X ₁ to X ₆ are the same as or different from each other, and each of X ₁ to X ₆ may independently be any one of sulfur, selenium and oxygen atoms.

m and n are the same as or different from each other, and m and n are each independently an integer of 2 to 8.

The structural formula 1 may be a compound represented by the following general formula (1).

[Chemical Formula 1]

In another aspect of the present invention, there is provided a semiconductor device comprising: a substrate; A source electrode formed on the substrate and including graphene; A drain electrode formed on the substrate and including graphene; A semiconductor layer formed between the source electrode and the drain electrode and including a bipolar polymer semiconductor compound; Wherein the bipolar polymer semiconductor compound is a compound according to claim 1. [

And may further include self-assembled monolayers between the substrate and the semiconductor layer.

According to another aspect of the present invention, there is provided a method of manufacturing a graphene substrate, comprising: (a) forming graphene on a substrate to produce a laminate 1 of graphene / substrate; (b) patterning the graphene of the layered product 1 to form a source / drain electrode including a source electrode including graphene and a drain electrode including graphene to manufacture a laminate 2 of the source / drain electrode / substrate ; And (c) forming a semiconductor layer including the bipolar polymer semiconductor according to claim 1 between the source electrode and the drain electrode of the stacked body 2 to manufacture a stacked body 3 of a semiconductor layer / a source / drain electrode / substrate; And a method of manufacturing the organic thin film transistor.

Forming a self-assembled monolayer on the substrate between the source electrode and the drain electrode of the laminate 2 between steps (b) and (c).

The self-assembled monolayer includes octadecyltrimethoxylane, trimethoxy (3,3,3-trifluoropropyl) silane and trichloro (3,3,3-trifluoropropyl) silane. (phenethyl) silane).

The patterning of step (b) may be performed by photolithography.

In step (c), the bipolar polymer semiconductor layer may be formed as a coating.

The coating may be at least one selected from spin coating, drop casting, solution shearing, and inkjet printing.

According to another aspect of the present invention, there is provided a plasma display panel comprising: a plurality of organic thin film transistors including a source electrode and a drain electrode; And

And a connection line electrically connecting the gate electrode, the source electrode, and the drain electrode of the plurality of organic thin film transistors to one another, wherein the organic thin film transistor includes: a flexible substrate; The gate electrode formed on the flexible substrate; An insulating layer formed on the gate electrode; The source electrode formed on the insulating layer and including graphene; The drain electrode formed on the insulating layer and including graphene; A semiconductor layer formed between the source electrode and the drain electrode, the semiconductor layer including the bipolar polymer semiconductor compound according to claim 1; And a flexible organic thin film transistor array.

The gate electrode may be formed of a material selected from the group consisting of Au, Al, Ag, Be, Bi, Co, Cu, Cr, Hf, In, Mn, Mo, Mg, Ni, Nb, Pb, Pd, Pt, Rh, , Ta, Te, Ti, V, W, Zr, and Zn.

The graphene electrode is located on the gate insulating film and can be used as a source and a drain electrode.

The flexible organic thin film transistor array may be a sensor for detecting a chemical substance including acetone, ethanol, and chlorobenzene.

In another aspect of the present invention, there is provided a method of manufacturing a semiconductor device, comprising the steps of: (a) forming a patterned gate electrode on a substrate to form a layered body a of a patterned gate electrode / substrate; (b) forming an insulating layer on the patterned gate electrode of the layered product a to produce a layered product b of an insulating layer / patterned gate electrode / substrate; (c) forming graphene on the insulating layer of the laminate b to produce a laminate c of a graphene / insulating layer / patterned gate electrode / substrate; (d) patterning the graphene of the layered product (c) to form a source / drain electrode including a source electrode including graphene and a drain electrode including graphene to form a source / drain electrode / insulating layer / patterned gate electrode / Fabricating a laminate d of a substrate; (e) forming a patterned photoresist on the substrate in the direction of the source and drain electrodes of the stacked body d, thereby forming a laminated body e of the patterned photoresist / source / drain electrode / insulating layer / patterned gate electrode / ;

(f) forming a connection line between the source electrode and the drain electrode using the patterned photoresist of the layered product (e) and removing the patterned photoresist to form a connection line / source / drain electrode / insulation layer / patterned gate Fabricating a laminate (f) of electrodes / substrates; And (g) a semiconductor layer including the bipolar polymer semiconductor compound of claim 1 is formed between the source electrode and the drain electrode of the laminate f to form a semiconductor layer / connection lead / source / drain electrode / insulation layer / patterned gate electrode / Lt; RTI ID = 0.0 > g < / RTI > And a method of manufacturing the flexible organic thin film transistor array.

The flexible substrate may be any one selected from the group consisting of polyimide, polyethylene terephthalate (PET), and polyester.

The patterning may be performed by photolithography.

The bipolar polymer semiconductor material containing the siloxane group of the present invention is excellent in water repellency and chemical resistance, and has an excellent effect of forming a thin film.

In addition, the bipolar polymer semiconductor material of the present invention is suitable for a photolithography process and can realize a fine pattern, and it is possible to realize a large area organic transistor and a chemical sensor having excellent efficiency.

1 shows a molecular structure of a bipolar polymer semiconductor produced according to Example 1. Fig.
2 is a schematic diagram showing a BGBC structure transistor manufactured according to the first embodiment of the present invention.
3 shows a manufacturing process of a flexible transistor array including a bipolar polymer semiconductor thin film manufactured according to Embodiment 1 based on graphene electrodes.
4 shows a Raman spectrum analysis result of the graphene electrode.
5 is an AFM image of a thin film organic graphene electrode including a bipolar polymer semiconductor of Example 1 and a silicon wafer.
6 shows a 2D GIXD analysis result of a bipolar polymer semiconductor thin film on SiO ₂ and graphene.
FIG. 7 shows the pole point results for the diffraction of the bipolar polymer semiconductor thin film on SiO ₂ and graphene.
FIG. 8 shows the IV characteristic (a) of the graphene electrode-based PTDPPSe-SiC4 transistor during the p-channel driving and the IV characteristic (b) during the n-channel driving.
9 shows the difference in energy level of graphene, PTDPPSe-SiC4, and gold.
10 shows driving characteristics of a graphene electrode-based PTDPPSe-SiC4 inverter.
11 shows the hole mobility mapping result of the transistor array.
Fig. 12 shows the measurement result of the performance change when the transistor array is bent.
13 is an image showing the result of solvent resistance analysis for a chlorobenzene solvent.
FIG. 14 shows the results of analyzing electron and hole mobility characteristics according to the type of solvent held in the transistor array.
15 shows the current change of the transistor with exposure of the acetone vapor.

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.

As used herein, "hydrogen" means monohydrogen, double hydrogen, or tritium, unless otherwise defined.

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 C20 alkyl group. More specifically, the alkyl group may be a C1 to C15 alkyl group, a C1 to C10 alkyl group or a C1 to C6 alkyl group.

For example, the C1 to C6 alkyl group may have 1 to 6 carbon atoms in the alkyl chain, that is, the alkyl chain may be a methyl group, an ethyl group, a propyl group, an iso-propyl group, , a t-butyl group, a pentyl group, a hexyl group, an ethynyl group, a propenyl group, a butenyl group, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group or a cyclohexyl group.

Hereinafter, the bipolar polymer semiconductor compound of the present invention will be described with reference to FIG.

The present invention provides a bipolar polymer semiconductor compound represented by the following structural formula (1).

[Structural formula 1]

In the above formula 1,

R ₁ to R ₁₄ are the same or different from each other, and R ₁ to R ₁₄ are independently of each other a C ₁ to C 20 linear or branched alkyl group,

X ₁ to X ₆ are the same or different from each other, and X ₁ to X ₆ are each independently any one of the Group 16 atoms,

m and n are the same or different from each other, m and n are each independently an integer of 1 to 15,

p is the number of repeating units,

The number average molecular weight is from 5,000 to 1,000,000.

Preferably, R ₁ to R ₁₄ are the same or different from each other, and R ₁ to R ₁₄ may be any one independently selected from a methyl group and an ethyl group, and more preferably a methyl group.

X ₁ to X ₆ are the same or different from one another and each of X ₁ to X ₆ may independently be any one of sulfur, selenium and oxygen atoms, preferably X ₁ and X ₂ may be an oxygen atom, X ₃ and X ₆ may be the same or different from each other, and X ₃ and X ₆ may each independently be any one of sulfur and selenium atoms.

Preferably, m and n are the same or different from each other, and m and n are each independently an integer of 2 to 8, more preferably 3 to 6.

Preferably, the compound represented by Formula 1 may be a compound represented by Formula 1 below.

[Chemical Formula 1]

Hereinafter, a graphene-based organic thin film transistor including the bipolar polymer compound of the present invention will be described.

The present invention relates to a substrate; A source electrode formed on the substrate and including graphene; A drain electrode formed on the substrate and including graphene; A semiconductor layer formed between the source electrode and the drain electrode and including a bipolar polymer semiconductor compound; Wherein the bipolar polymer semiconductor compound is a compound according to claim 1. [

And may further include self-assembled monolayers between the substrate and the semiconductor layer.

The graphene electrode may be a source electrode and a drain electrode.

In the past, gold was deposited on the source and drain electrodes to fabricate the transistor. However, instead of using gold as a source and a drain electrode, the organic thin film transistor was implemented using graphene.

When graphene is used instead of gold for the source and drain electrodes, there is an advantage that a difference in work function level around the semiconductor layer energy and the electrode is reduced to realize a high charge mobility and a balanced bipolar transistor.

The organic thin film transistor including the bipolar polymer semiconductor of the present invention can be manufactured in the following order.

First, graphene is formed on a substrate to produce a laminate 1 of graphene / substrate (step a).

Next, the graphene of the layered product 1 is patterned to form a source / drain electrode including a source electrode including graphene and a drain electrode including graphene, thereby manufacturing a laminate 2 of the source / drain electrode / substrate (Step b).

The patterning may be performed by photolithography.

Next, a semiconductor layer including the bipolar polymer semiconductor according to the first aspect is formed between the source electrode and the drain electrode of the stacked body 2 to produce a stacked body 3 of semiconductor layer / source / drain electrode / substrate (step c) .

Forming a self-assembled monolayer on the substrate between the source electrode and the drain electrode of the laminate 2 between steps (b) and (c).

The self-assembled monolayer may include a silane compound derivative. Preferably, the silane compound derivative is selected from the group consisting of octadecyltrimethoxylane, trimethoxy (3,3,3-trifluoropropyl) silane, 3,3,3-trifluoropropyl) silane, and trichloro (phenethyl) silane, and more preferably octadecyltrimethoxysilane.

The bipolar polymer semiconductor layer may be formed of a coating. Preferably, the coating may be spin coating, drop casting, solution shearing, inkjet printing, or the like.

Hereinafter, a flexible organic thin film transistor array device including a bipolar polymer semiconductor of the present invention will be described with reference to FIG.

A plurality of organic thin film transistors including a source electrode and a drain electrode; And a connection line electrically connecting the gate electrode, the source electrode, and the drain electrode of the plurality of organic thin film transistors to one another, wherein the organic thin film transistor includes a flexible substrate; The gate electrode formed on the flexible substrate; An insulating layer formed on the gate electrode; The source electrode formed on the insulating layer and including graphene; The drain electrode formed on the insulating layer and including graphene; A semiconductor layer formed between the source electrode and the drain electrode, the semiconductor layer including the bipolar polymer semiconductor compound according to claim 1; And a flexible organic thin film transistor array.

The gate electrode may be formed of a material selected from the group consisting of Au, Al, Ag, Be, Bi, Co, Cu, Cr, Hf, In, Mn, Mo, Mg, Ni, Nb, Pb, Pd, Pt, Rh, , Ta, Te, Ti, V, W, Zr, and Zn.

The flexible organic thin film transistor array may be a sensor for detecting chemical substances such as acetone, ethanol, chlorobenzene, and water.

The above flexible organic thin film transistor array can be manufactured in the following order.

First, a patterned gate electrode is formed on a substrate to produce a layered body a of a patterned gate electrode / substrate (step a).

The substrate may be a transparent substrate on which a transparent polyimide is formed.

Next, an insulating layer is formed on the patterned gate electrode of the layered product a to produce a layered product b of an insulating layer / patterned gate electrode / substrate (step b).

Next, graphenes are formed on the insulating layer of the laminate b to prepare a laminate c of a graphene / insulating layer / patterned gate electrode / substrate (step c).

Next, the graphene of the layered product c is patterned to form a source / drain electrode including a source electrode including graphene and a drain electrode including graphene to form a source / drain electrode / insulating layer / patterned gate electrode / A laminate d of the substrate is prepared (step d).

Next, a patterned photoresist is formed on the substrate in the direction of the source and drain electrodes of the stacked body d to form a layered body e of the patterned photoresist / source / drain electrode / insulating layer / patterned gate electrode / substrate (Step e).

Next, the patterned photoresist of the layered product e is used to form a connection line between the source electrode and the drain electrode, and the patterned photoresist is removed to form a connection line / source / drain electrode / insulation layer / patterned gate The laminate f of the electrode / substrate is removed (step f).

Finally, a semiconductor layer including the bipolar polymer semiconductor compound of claim 1 is formed between the source electrode and the drain electrode of the laminate f to form a semiconductor layer / connection lead / source / drain electrode / insulation layer / patterned gate electrode / A laminate g is prepared (step g).

The flexible substrate may be made of polyimide, polyethylene terephthalate (PET), polyester or the like, preferably polyimide, and the type of the flexible substrate is limited thereto It is not.

The patterning may be performed by photolithography.

Hereinafter, the present invention will be described more specifically by way of examples. However, this is for illustrative purposes only, and thus the scope of the present invention is not limited thereto.

 [Example]

Example  1: bipolar polymer semiconductor

Monomer dibrominated dithienyl-diketopyrrolopyrrole (TDPP) ( 0.20 mmol) and the monomer distannyl selenophene comonomer into a (0.20 mmol) and the catalyst is tris (dibenzylidenacetone) dipalladium (0) toluene in a (2.0 m mol) in anhydrous (4 mL) in an argon atmosphere And stirred for 30 minutes. To this solution was added tri (o -tolyl) phosphine (4.0 m mol) into the ligand was a 12-hour reaction was heated to a temperature of 95 ℃.

After the reaction, the solution was cooled to room temperature, and the reaction solution was poured into methanol (300 mL) to precipitate a polymer solid. The polymeric solid was subjected to purification by methanol, acetone, and hexane for one day through continuous Soxhlet extraction. The purified polymer was finally dissolved in chloroform and precipitated in methanol (300 mL) to precipitate a final polymer, which was then dried in a vacuum oven to prepare a bipolar polymer semiconductor (yield: 75%, molecular weight: M _n = 25.1 kDa, M _w = 89.3 kDa, PDI = 3.56)

^{_{1 H NMR (C 2 D 2}} Cl 4, 600 MHz, 348 K): d ppm 9.25-8.71 (br, 2H), 7.37-6.68 (br, 4H), 4.22-3.66 (br, 4H), 2.08-1.73 (br, 2H), 1.42-1.06 (br, 64H), 0.85-0.78 (br, 12H).

Molecular element analysis: Anal. Calcd. for C ₄₀ H ₆₆ N ₂ O ₆ S ₂ Se ₆ Si ₆ : C, 48.90; H, 6.77 N, 2.85 Found: C, 70.61; H, 8.97, N, 2.63.

Device Example  1-1: Grapina  Electrode, an organic thin film transistor including a bipolar polymer semiconductor

(Step 1: graphen transfer)

A copper foil was placed in a CVD apparatus, and hydrogen gas and methane gas were injected while heating at a temperature of 1000 ° C to form graphene on the copper foil to prepare a graphene / copper laminate. A solution (20 mg / mL) in which a PMMA polymer was dissolved in a chlorobenzene solvent was coated on the graphene of the laminate and heated at a temperature of 100 ° C for 1 hour to prepare a PMMA / graphene / copper laminate.

The copper foil was etched so that the copper portion of the laminate came into contact with an aqueous 0.1M ammonium persulfate solution to prepare a PMMA / graphene thin film. The thin film was transferred onto the distilled water using a PET film. The thin film on the distilled water was transferred to a highly doped Si substrate on which SiO ₂ (300 nm) was thermally grown by a wet-transfer method and heated at a temperature of 130 ° C. for 1 hour to obtain a PMMA / . After heating, the laminate was immersed in acetone to remove the coated PMMA layer to prepare a graphene / substrate laminate to which graphene was transferred.

(Step 2: patterning)

A photoresist (DSAM-300) was coated on the thus-prepared laminate by spin coating and irradiated with ultraviolet rays selectively using a photomask. Then, the photoresist was immersed in a developer DPD-200 to remove a portion of the photoresist irradiated with ultraviolet rays A graphene / substrate laminate having a photoresist pattern formed thereon was prepared.

The laminate was subjected to an oxygen plasma treatment to selectively remove the graphene layer not covered with the photoresist to prepare a graphene electrode pattern. The remaining photoresist was immersed in a DMSO solvent to remove any remaining photoresist, Thereby producing a substrate laminate having an electrode pattern formed thereon.

(Step 3: Formation of polymer semiconductor thin film)

The substrate laminate formed with the graphene electrode was placed in a reactor together with 0.2 mL of octadecyltrimethoxysilane to form a vacuum state, which was then heated at a temperature of 140 ° C for 12 hours to form a self-assembled monolayer, / Graphene electrode / substrate laminate was prepared and washed with toluene, acetone, isopropanol solvent.

(Step 4: Manufacture of organic thin film transistor)

Then, a solution (3 mg / mL) in which the bipolar polymer semiconductor (PTDPPSe-SiC4) prepared according to Example 1 was dissolved in chlorobenzene solvent was spin-coated on the laminate to prepare a bipolar polymer semiconductor thin film And heated at a temperature of 200 ° C for 30 minutes to prepare an organic thin film transistor including a graphene electrode and a bipolar polymer semiconductor.

Device Example  1-2: Grapina  Electrode, an organic thin film transistor including a bipolar polymer semiconductor

Instead of forming a bipolar polymer semiconductor thin film by coating a solution obtained by dissolving the bipolar polymer semiconductor prepared in Example 1 in Step 3 of Example 1-1 in a spin coating process, the polymer was coated by drop-casting to form a bipolar An organic thin film transistor was fabricated in the same manner as in Example 1-1 except that a polymer semiconductor thin film was formed.

Device Example  1-3: Grapina  Electrode, an organic thin film transistor including a bipolar polymer semiconductor

Instead of forming the bipolar polymer semiconductor thin film by coating the solution obtained by dissolving the bipolar polymer semiconductor prepared in Example 1 in Step 3 of Example 1-1 with spin coating, the solution was coated by solution-shearing Except that a bipolar polymer semiconductor thin film was formed on the surface of the bipolar polymer semiconductor thin film.

Device Example  2: A thin film comprising a bipolar polymer semiconductor thin film Flexible  Organic Thin Film Transistor Array

(Step 1: gate electrode fabrication)

A transparent polyimide solution was coated on a clean glass plate by a spin-coating method, and then coated at a temperature of 100 캜 for 2 hours, a temperature of 200 캜 for 2 hours, a temperature of 300 캜 for 2 hours, To prepare a transparent polyimide / glass plate laminate.

A photoresist was coated on the transparent polyimide layer of the laminate by spin coating and irradiated with ultraviolet rays selectively using a photomask. Then, the photoresist was immersed in DPD-200 to remove the photoresist portion irradiated with ultraviolet rays.

(4 nm) and gold (40 nm) were deposited on the polyimide / organic plate laminate having the photoresist pattern formed thereon by thermal evaporation to prepare a gate electrode pattern. Then, the photoresist remaining in the DMSO solvent was removed, Thereby producing a laminate having electrode patterns formed thereon.

(Step 2: formation of an insulating layer on the gate electrode)

A mixed solution of SU-810 and gamma-butylacetone in a volume ratio of 7: 3 was coated on the laminate having the gate electrode pattern formed thereon by an epoxy-based photoresist and dielectric substance was spin-coated, And heated for 1 minute. Subsequently, the SU-8 10 thin film was exposed to ultraviolet rays for crosslinking and then heated at a temperature of 150 ° C for 30 minutes.

(Step 3: formation of a graphene layer on the insulating layer)

A copper foil was placed in a CVD apparatus and hydrogen gas and methane gas were injected while being quadrupled at a temperature of 1000 ° C to form graphene on the copper foil to prepare a graphene / copper laminate. A solution (20 mg / mL) in which a PMMA polymer was dissolved in a chlorobenzene solvent was coated on the graphene of the laminate and heated at a temperature of 100 ° C for 1 hour to prepare a PMMA / graphene / copper laminate. Thereafter, the copper foil was etched so that the copper portion of the laminate came into contact with an aqueous 0.1M ammonium persulfate solution to prepare a PMMA / graphene thin film. The thin film was transferred onto the distilled water using a PET film.

The PMMA / graphene thin film was transferred onto the SU-8 10 thin film by a wet-transfer method, heated at 130 for 1 hour, immersed in acetone, and PMMA was removed to prepare a graphene transferred substrate.

(Step 4: formation of graphene pattern)

The photoresist (DSAM-300) was coated on the substrate by spin coating and irradiated with ultraviolet rays selectively using a photomask. Then, the photoresist was dipped in the developer DPD-200 to remove the photoresist in the portion irradiated with ultraviolet rays, To prepare a patterned graphene / substrate laminate.

The laminate was subjected to an oxygen plasma treatment to selectively remove the graphene layer not covered with the photoresist to prepare a graphene electrode pattern. The remaining photoresist was immersed in a DMSO solvent to remove any remaining photoresist, Thereby producing a substrate laminate having an electrode pattern formed thereon.

The photoresist (DSAM-300) was spin-coated on the substrate laminate having the graphene electrode pattern formed thereon and selectively irradiated with ultraviolet rays using a photomask, and then immersed in DPD-200 to remove the photoresist in the portion irradiated with ultraviolet rays Respectively.

(Step 5: formation of source and drain electrodes)

The source and drain electrode connecting lines and contact pad patterns were prepared by depositing chromium (4 nm) and gold (40 nm) on the substrate on which the photoresist pattern was formed by thermal evaporation, and then the remaining photoresist was immersed in DMSO solvent.

(Step 6: formation of bipolar polymer thin film)

A mixed solution (3 mg / mL) of chlorobenzene solvent and a bipolar polymer semiconductor (PTDPPSe-SiC4) was spin-coated on a substrate having both electrode pattern and connecting line pattern formed thereon to form a thin film. And heated at a temperature for 30 minutes to form a bipolar polymer semiconductor thin film.

(Step 7: bipolar polymer pattern formation and flexible organic thin film transistor array fabrication)

A photoresist (DSAM-300) was coated on the formed PTDPPSe-SiC4 thin film by spin coating and selectively irradiated with ultraviolet rays using a photomask. Then, the photoresist was removed from the portion irradiated with ultraviolet light by immersing in DPD-200.

The substrate on which the photoresist pattern was formed was subjected to reactive ion etching (RIE) to selectively remove the PTDPPSe-SiC4 thin film not covered with the photoresist, and then the remaining photoresist was removed by immersing in the DMSO solvent to remove the PTDPPSe-SiC4 semiconductor pattern To fabricate a flexible organic thin film transistor array.

Device comparison example  One: Flexible  Organic Thin Film Transistor Array

An organic thin film transistor was fabricated in the same manner as in Example 1-1 except that gold was used as a source electrode and a drain electrode instead of the graphene electrode of Example 1-1.

Device comparison example  2: Flexible  Organic Thin Film Transistor Array

An organic thin film transistor was fabricated in the same manner as in Example 1-2, except that gold was used as the source electrode and the drain electrode instead of the graphene electrode of Example Embodiment 1-2.

Device comparison example  3: Flexible  Organic Thin Film Transistor Array

An organic thin film transistor was fabricated in the same manner as in Example 1-3 except that gold was used as a source electrode and a drain electrode instead of the graphene electrode of Embodiment 1-3.

Device comparison example  4: Flexible  Organic Thin Film Transistor Array

A flexible organic thin film transistor array was fabricated in the same manner as in Example 2 except that a semiconductor thin film was formed using a P3HT semiconductor instead of the bipolar polymer semiconductor of Example 1.

[Test Example]

Test Example 1: Analysis of patterned graphene layer on a substrate - optical image and Raman spectrum

Figure 4 shows optical image analysis and Raman spectrum analysis of a graphene / substrate laminate prepared according to Example 2 to analyze patterned graphene on a substrate.

Referring to FIG. 4, it was confirmed that no peak appeared in the Raman spectra corresponding to gray-dots. This means that there is no graphene where the gray dot is located, which means that the graphene is well etched during the patterning process.

The pink-dot position showed strong G band (~ 1580 cm ^-1 ) and 2D band (~ 2700 cm ^-1 ). This means that a single layer of graphene is formed.

The purple-dot position showed a slightly 2D band rather than the pink dot position, indicating that a few-layer graphene was formed.

In addition, the Raman spectrum of the blue-dot position at the edge of the patterned graphene electrode shows a D band, which means that defects are formed in the patterning process. As a result, the grating structure of the graphene electrode Of discontinuity.

Test Example  2: solution shear By process  Patterned Grapina / On the substrate  Surface morphology analysis of formed bipolar polymer semiconductor thin film - Atomic microscope analysis

5 is an atomic force microscope image of the organic thin film transistor of Example 1-3 in which a thin film was formed by a solution front end process to analyze the surface morphology of the bipolar polymer semiconductor thin film.

Referring to FIG. 5, alignment of the polymer semiconductor chains induced by the shear stress applied during the solution shear process was observed on the SiO2 surface.

On the other hand, it was confirmed that the polymer chains of the polymer semiconductor thin film on the graphene film were randomly oriented.

This result appears to be due to the fact that the π-π interaction between the honeycomb lattice of the graphene and the conjugated polymer chain is strong enough to resist polymer chain alignment to shear stress.

Therefore, it was confirmed that there is a difference in morphology depending on the presence of graphene located under the polymer semiconductor thin film.

Test Example  3: SiO ₂  And Grapina  Crystallinity and directional analysis of bipolar polymer semiconductors - 2D-GIXD analysis and pole figure analysis

FIG. 6 shows the results of 2D-GIXD analysis for analyzing the molecular directionality and crystallinity of the bipolar polymer semiconductor of graphene and SiO ₂ phase.

Referring to FIG. 6, SiO ₂ and the thin film formed by the solution process on the graphene showed a high-order (h00) peak up to the fourth order along the out-of-plane direction.

The coherence length Lc of SiO ₂ was about 133 Å in the out-of-plane direction, but about 240 Å in the in-plane direction in graphene.

The (010) peak observed at q = 1.7 Å ^-1 in the in-plane and out-of-plane directions corresponds to π-π stacking indicating the formation of a 3D hole conduction channel in the PTDPPSe-SiC4 film on SiO ₂ . On the other hand, the films on graphene showed strong π-π stacking peaks (qz = 1.687 Å) only in the out-of-plane direction.

Fig. 7 shows the result of pole figure analysis for (010) diffraction to quantitatively compare π-π stacking in a polymer film made of SiO ₂ and graphene.

Referring to FIG. 7, PTDPPSe-SiC4 on SiO ₂ is characterized by a barbic distribution in the pi system with an edge-on portion of 16.5% and a face-on portion of 83.5%, while the grains have a face-on portion of 98% With only 2% of the edges.

Also, the π-π stacking between the conjugate scaffolds was not affected by changes in the X-ray penetration depth generated by adjusting the X-ray incidence angle, which is due to strong π-π interactions between PTDPPSe-SiC4 and graphene in the out- Means the presence of action.

Test Example  4: Device Example  Transmission characteristics of n-channel and p-channel of organic thin film transistor fabricated according to

8 shows the results of analyzing the p-channel migration characteristic and the n-channel migration characteristic of the organic thin film transistor manufactured according to the Embodiment 1-3.

Referring to FIG. 8, the maximum hole mobility and electron mobility were 1.43 and 0.37 cm ² V ^-1 s ^-1 , respectively. Due to the difference in device structure, the hole and electron mobility in the BGBC geometry was slightly lower than the hole and electron mobility of the previously reported top-contact device, but this mobility is similar to that of amorphous silicon Respectively.

Table 1 below shows the results of hole and electron mobility of the PTDPPSe-SiC4 film using spin coating, drop casting, and solution shear process.

electrode device μ _{h, avg}
[cm ² V ^-1 s ^-1 ] μ _{h, max}
[cm ² V ^-1 s ^-1 ] I _on / I _{off, h} mu _{e, avg}
[cm ² V ^-1 s ^-1 ] μ _{e, max}
[cm ² V ^-1 s ^-1 ] I _on / I _{off, e} Grapina Device Example 1-1 0.56 (+ -0.22) 0.86 > 10 ⁴ 0.06 (+/- 0.05) 0.11 > 10 ³ Device Example 1-2 0.79 (+ -0.27) 1.17 > 10 ⁴ 0.09 (0.08) 0.22 > 10 ³ Device Embodiment 1-3 1.00 (+ - 0.26) 1.43 > 10 ⁵ 0.20 (+/- 0.10) 0.37 > 10 ² gold Device Comparative Example 1 0.29 (0.03) 0.33 > 10 ⁵ 0.004 (+/- 0.002) 0.007 > 10 ³ Device Comparative Example 2 0.31 (+/- 0.09) 0.43 > 10 ⁴ 0.004 (+/- 0.002) 0.009 > 10 ² Device Comparative Example 3 0.33 (0.08) 0.54 > 10 ⁵ 0.004 (+/- 0.002) 0.009 > 10 ²

Referring to Table 1, it can be seen that the device manufactured using the solution shear process has the highest mobility since the degree of molecular dying after the solution shearing is high.

The electric performance of the organic field effect transistor having a graphene electrode is compared with that of the Cr / Au electrode of the BGBC structure. The hole mobility of the transistor using the Cr / Au electrode is higher than the hole mobility of the transistor using the graphene electrode I can confirm that it is low.

Further, the electron mobility of the transistor having the Cr / Au electrode was 5% of the electron mobility of the transistor including the graphene electrode, and it was confirmed that the organic field effect transistor of the present invention has excellent electrical performance.

Test Example 5: Energy diagram analysis of graphene, gold, and bipolar polymer semiconductors

Figure 9 shows the energy levels of PTDPPSe-SiC4 and graphene and gold electrodes.

9, the HOMO and LUMO levels of the PTDPPSe-SiC4 were -5.17 and -3.56 eV, respectively, and the work functions of the graphene electrode and gold electrode were -4.5 and -5.1Ev, respectively.

Thus, using graphene electrodes instead of gold could confirm that electron transport achieved a lower energy barrier. A low energy barrier for n-type operation (n-type operation) is more advantageous for electron transfer when using graphene electrodes, which is a negative effect on hole mobility due to high energy barrier to hole transport .

However, as shown in Table 1, it was confirmed that both the hole mobility and the electron mobility of the graphene electrode were improved. As a result, it was confirmed that the morphological factor had a greater influence on the electrical performance than the energy factor there was.

Test Example 6: Characteristic Analysis of Inverter Based on Organic Thin Film Transistor

Figure 10 shows the inverter characteristics of a graphene electrode based transistor.

Referring to FIG. 10, it can be seen that the gain of the gold electrode-based transistor is 7.9, while the gain of the graphene electrode-based transistor is 20.3.

These results suggest that the high gain of the graphene electrode transistor is due to the well-balanced high hole mobility.

Test Example 7: Characteristic Analysis of Inverter Based on Organic Thin Film Transistor

11 shows a hole mobility mapping image on a 10 X 10 flexible transistor array.

Referring to FIG. 11, it can be seen that the hole mobility is uniformly obtained in the manufactured 100 transistors.

Therefore, we can confirm that the device is fabricated with 100% yield.

Test Example 8: Analysis of hole mobility according to bending

12 is a graph showing changes in hole mobility with bending in order to analyze the bending characteristics of a flexible organic field effect transistor fabricated on a transparent polyimide substrate.

Shows a change in hole mobility as a function of the bending radius of 10 to 3 mm parallel and perpendicular to the shear direction. The tensile strain is as follows.

[Formula 1]

In Equation 1, ε _tensile represents the tensile strain, t represents the thickness of the base film, 0.1 mm, and R _bend represents the radius from the bending center to the center line of the film.

Element Example 1 exhibited an isotropic tendency to a gradual decrease in flexion direction and mobility compared to the initial mobility from 1.01% of the tensile strain (2R _bend = 10 mm) to a high tensile strain (3.23%). (2R _bend = 3 mm).

As a result of the bending test of fabricated FET array, the hole mobility at the bending radii of 10, 8, and 3 mm decreased to 95.5%, 68.2%, and 50.0% of the initial values, respectively. After releasing the deformation of the device, the mobility was restored to its original value.

This reversible mobility change is thought to be due to the flexible nature of the device components.

Test Example  9: Grapina  Using electrodes PTDPPS - SiC4  Solvent resistance analysis of transistor

13 schematically shows an experimental method for analyzing solvent resistance.

In order to analyze the solvent resistance, the transistor manufactured according to Example 1 was immersed in a chlorobenzene solvent for 24 hours, and then a nitrogen gas was introduced and heated at a temperature of 220 캜 under a nitrogen gas to remove the solvent. A conventional film prepared by depositing a poly (3-hexylthiophene) (P3HT) film on a SiO ₂ / Si wafer was immersed in chlorobenzene and compared.

13, the color of the chlorobenzene containing the P3HT film changed to yellow and the color of the chlorobenzene containing the PTDPPSe-SiC4 film remained unchanged.

Therefore, the solvent resistance of the thin film containing the bipolar polymer semiconductor (PTDPPS-SiC4) of the present invention was analyzed to be stronger than that of the conventional film.

Test Example 10: Chemical resistance analysis for solvent

Fig. 14 shows the results of hole and electron mobility analysis of FET devices before and after immersing them in a solvent.

Referring to FIG. 14, although the hole and hole mobility of the transistor was lowered before being immersed in the solvent, the transistors all operated well.

Therefore, the bipolar polymer semiconductor (PTDPPS-SiC4) thin film of the present invention has high insolubility and high chemical resistance.

Test Example 11: Acetone sensing characteristics of PTDPPSe-SiC4 FET array

Figure 15 shows a schematic diagram of acetone sensing using a PTDPPSe-SiC4 FET array and an analysis of acetone vapor sensing.

To briefly demonstrate the feasibility of the PTDPPSe-SiC4 OFET as a platform for chemical sensors, the PTDPPS-SiC4 FET was exposed to an acetone vapor stream (4 SLM) capable of on / off switching (Figure 4e).

Referring to Figure 15 (b), a mixture of acetone vapor and air appeared to explode when the concentration range of acetone was 2.6-12.8%.

Exposure to acetone vapor reduces the drain current and results in destructive (negative) sensing behavior. Exposure to the vapor was generally analyzed to reduce the hole current due to hole trapping induced by the dipole at the grain boundary of the organic semiconductor layer.

Acetone is a polar and electron donating material and shows a destructive sense signal at the hole current. The acetone sensor based on the organic field effect transistor of the present invention showed stable operation in the acetone gas OFF region.

Accordingly, it is considered that the organic thin film transistor array of the present invention can obtain a stable and repetitive sensing signal, and that the organic field effect transistor device of the present invention can be used as a chemical sensing platform.

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 (19)

A plurality of organic thin film transistors including a source electrode and a drain electrode; And
And a connection conductor electrically connecting the gate electrode, the source electrode, and the drain electrode of the plurality of organic thin film transistors to each other,
The organic thin film transistor
Flexible substrate;
The gate electrode formed on the flexible substrate;
An insulating layer formed on the gate electrode;
The source electrode formed on the insulating layer and including graphene;
The drain electrode formed on the insulating layer and including graphene; And
A semiconductor layer formed between the source electrode and the drain electrode and including a bipolar polymer semiconductor compound represented by the following structural formula 1; ≪ / RTI >
Flexible organic thin film transistor array.
[Structural formula 1]

In the above formula 1,
R ₁ to R ₁₄ are the same or different from each other, and R ₁ to R ₁₄ are independently of each other a C ₁ to C 20 linear or branched alkyl group,
X ₁ to X ₆ are the same or different from each other, and X ₁ to X ₆ are each independently any one of the Group 16 atoms,
m and n are the same or different from each other, m and n are each independently an integer of 1 to 15,
p is the number of repeating units,
The number average molecular weight is from 5,000 to 1,000,000. The method according to claim 1,
Wherein R ₁ to R ₁₄ are the same or different from each other and each of R ₁ to R ₁₄ is independently selected from methyl group and ethyl group. The method according to claim 1,
Wherein X ₁ to X ₆ are the same or different from each other and each of X ₁ to X ₆ is independently any one of sulfur, selenium and oxygen atoms. The method according to claim 1,
m and n are the same or different from each other, and m and n are each independently an integer of 2 to 8. The method according to claim 1,
Wherein the structural formula (1) is represented by the following formula (1).
[Chemical Formula 1]

delete delete delete delete delete delete delete delete delete The method according to claim 1,
The gate electrode may be formed of a material selected from the group consisting of Au, Al, Ag, Be, Bi, Co, Cu, Cr, Hf, In, Mn, Mo, Mg, Ni, Nb, Pb, Pd, Pt, Rh, , Ta, Te, Ti, V, W, Zr, and Zn. The method according to claim 1,
Wherein the flexible organic thin film transistor array is a sensor for detecting at least one selected from the group consisting of acetone, water, ethanol, and chlorobenzene. (a) forming a patterned gate electrode on a substrate to produce a layered body a of a patterned gate electrode / substrate;
(b) forming an insulating layer on the patterned gate electrode of the layered product a to produce a layered product b of an insulating layer / patterned gate electrode / substrate;
(c) forming graphene on the insulating layer of the laminate b to produce a laminate c of a graphene / insulating layer / patterned gate electrode / substrate;
(d) patterning the graphene of the layered product (c) to form a source / drain electrode including a source electrode including graphene and a drain electrode including graphene to form a source / drain electrode / insulating layer / patterned gate electrode / Fabricating a laminate d of a substrate;
(e) forming a patterned photoresist on the substrate in the direction of the source and drain electrodes of the stacked body d, thereby forming a laminated body e of the patterned photoresist / source / drain electrode / insulating layer / patterned gate electrode / ;
(f) forming a connection line between the source electrode and the drain electrode using the patterned photoresist of the layered product (e) and removing the patterned photoresist to form a connection line / source / drain electrode / insulation layer / patterned gate Fabricating a laminate (f) of electrodes / substrates; And
(g) A semiconductor layer including a bipolar polymer semiconductor compound represented by the following structural formula 1 is formed between the source electrode and the drain electrode of the stacked body f to form a semiconductor layer / connection lead / source / drain electrode / insulation layer / / Producing a laminate g of the substrate; To
A method for fabricating a flexible organic thin film transistor array comprising:
[Structural formula 1]

In the above formula 1,
R ₁ to R ₁₄ are the same or different from each other, and R ₁ to R ₁₄ are independently of each other a C ₁ to C 20 linear or branched alkyl group,
X ₁ to X ₆ are the same or different from each other, and X ₁ to X ₆ are each independently any one of the Group 16 atoms,
m and n are the same or different from each other, m and n are each independently an integer of 1 to 15,
p is the number of repeating units,
The number average molecular weight is from 5,000 to 1,000,000. 18. The method of claim 17,
Wherein the substrate is any one selected from the group consisting of polyimide, polyethylene terephthalate (PET), and polyester. 18. The method of claim 17,
Wherein the patterning is performed by photolithography. ≪ RTI ID = 0.0 > 21. < / RTI >

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