Conductive organic semiconductor compound, method for preparing the same and organic thin-film transistor including the same

Abstract

The present disclosure provides an organic semiconductor compound, which has superior charge mobility, low band gap, wide light absorption area and adequate molecular energy level. The conductive organic semiconductor compound of the present disclosure can be used as a material for various organic optoelectric devices such as an organic photodiode (OPD), an organic light-emitting diode (OLED), an organic thin-film transistor (OTFT), an organic solar cell, etc. In addition, it can be prepared into a thin film via a solution process, can be advantageously used to fabricate large-area devices and can reduce the cost of device fabrication.

Claims

1. A conductive organic semiconductor compound represented by [Chemical Formula I] or [Chemical Formula II]: ##STR00032## wherein Ar is selected from [Structural Formula 1] and n is an integer from 5 to 100,000: ##STR00033## ##STR00034## ##STR00035## ##STR00036## ##STR00037## wherein each of R.sub.1 and R.sub.2, which are identical or different, is independently selected from a group consisting of hydrogen, a halogen group, a cyano group, a nitro group, a hydroxyl group, an amide group, an ester group, a ketone group, a thioester group, a silyl group, a substituted or unsubstituted C.sub.1-C.sub.30 alkyl group, a substituted or unsubstituted C.sub.2-C.sub.30 alkenyl group, a substituted or unsubstituted C.sub.2-C.sub.30 alkynyl group, a substituted or unsubstituted C.sub.2-C.sub.50 heteroaryl group containing at least one of S, N, O, P and Si, a substituted or unsubstituted C.sub.3-C.sub.30 cycloalkyl group, a substituted or unsubstituted C.sub.3-C.sub.30 cycloalkenyl group, a substituted or unsubstituted C.sub.5-C.sub.50 aryl group, a substituted or unsubstituted C.sub.1-C.sub.30 alkoxy group, a substituted or unsubstituted C.sub.5-C.sub.50 aryloxy group, a substituted or unsubstituted C.sub.1-C.sub.30 alkylamino group, a substituted or unsubstituted C.sub.6-C.sub.30 arylamino group, a substituted or unsubstituted C.sub.1-C.sub.30 alkylsilyl group and a substituted or unsubstituted C.sub.5-C.sub.50 arylsilyl group.

2. The conductive organic semiconductor compound according to claim 1, wherein [Chemical Formula II] is represented by [Chemical Formula III] or [Chemical Formula IV]: ##STR00038## wherein each of R.sub.3 and R.sub.4, which are identical or different, is independently selected from a group consisting of hydrogen, a halogen group, a cyano group, a nitro group, a hydroxyl group, an amide group, an ester group, a ketone group, a thioester group, a silyl group, a substituted or unsubstituted C.sub.1-C.sub.30 alkyl group, a substituted or unsubstituted C.sub.2-C.sub.30 alkenyl group, a substituted or unsubstituted C.sub.2-C.sub.30 alkynyl group, a substituted or unsubstituted C.sub.2-C.sub.50 heteroaryl group containing at least one of S, N, O, P and Si, a substituted or unsubstituted C.sub.3-C.sub.30 cycloalkyl group, a substituted or unsubstituted C.sub.3-C.sub.30 cycloalkenyl group, a substituted or unsubstituted C.sub.5-C.sub.50 aryl group, a substituted or unsubstituted C.sub.1-C.sub.30 alkoxy group, a substituted or unsubstituted C.sub.5-C.sub.50 aryloxy group, a substituted or unsubstituted C.sub.1-C.sub.30 alkylamino group, a substituted or unsubstituted C.sub.6-C.sub.30 arylamino group, a substituted or unsubstituted C.sub.1-C.sub.30 alkylsilyl group and a substituted or unsubstituted C.sub.5-C.sub.50 arylsilyl group, and n is an integer from 5 to 100,000.

3. The conductive organic semiconductor compound according to claim 2, wherein [Chemical Formula III] is represented by [Chemical Formula V]: ##STR00039## wherein n is an integer from 5 to 100,000.

4. The conductive organic semiconductor compound according to claim 2, wherein [Chemical Formula IV] is represented by [Chemical Formula VI]: ##STR00040## wherein n is an integer from 5 to 100,000.

5. The conductive organic semiconductor compound according to claim 1, wherein the conductive organic semiconductor compound has an electron mobility of 110.sup.6 cm.sup.2/N.Math.s or higher.

6. The conductive organic semiconductor compound according to claim 1, wherein the conductive organic semiconductor compound has a band gap of 1.0-3.0 eV.

7. An organic semiconductor thin film comprising one or more conductive organic semiconductor compound, wherein the conductive organic semiconductor compound is represented by [Chemical Formula I] or [Chemical Formula II]: ##STR00041## wherein Ar is selected from [Structural Formula 1] and n is an integer from 5 to 100,000: ##STR00042## ##STR00043## ##STR00044## ##STR00045## ##STR00046## wherein each of R.sub.1 and R.sub.2, which are identical or different, is independently selected from a group consisting of hydrogen, a halogen group, a cyano group, a nitro group, a hydroxyl group, an amide group, an ester group, a ketone group, a thioester group, a silyl group, a substituted or unsubstituted C.sub.1-C.sub.30 alkyl group, a substituted or unsubstituted C.sub.2-C.sub.30 alkenyl group, a substituted or unsubstituted C.sub.2-C.sub.30 alkynyl group, a substituted or unsubstituted C.sub.2-C.sub.50 heteroaryl group containing at least one of S, N, O, P and Si, a substituted or unsubstituted C.sub.3-C.sub.30 cycloalkyl group, a substituted or unsubstituted C.sub.3-C.sub.30 cycloalkenyl group, a substituted or unsubstituted C.sub.5-C.sub.50 aryl group, a substituted or unsubstituted C.sub.1-C.sub.30 alkoxy group, a substituted or unsubstituted C.sub.5-C.sub.50 aryloxy group, a substituted or unsubstituted C.sub.1-C.sub.30 alkylamino group, a substituted or unsubstituted C.sub.6-C.sub.30 arylamino group, a substituted or unsubstituted C.sub.1-C.sub.30 alkylsilyl group and a substituted or unsubstituted C.sub.5-C.sub.50 arylsilyl group.

8. An organic thin-film transistor, comprising: a substrate; a gate electrode formed on the substrate; an insulating layer formed on the gate electrode; an organic semiconductor thin film formed on the insulating layer; and a source electrode layer and a drain electrode layer formed on the organic semiconductor thin film, wherein the organic semiconductor thin film includes one or more conductive organic semiconductor compound, wherein the conductive organic semiconductor compound is represented by [Chemical Formula I] or [Chemical Formula II]: ##STR00047## wherein Ar is selected from [Structural Formula 1] and n is an integer from 5 to 100,000: ##STR00048## ##STR00049## ##STR00050## ##STR00051## ##STR00052## wherein each of R.sub.1 and R.sub.2, which are identical or different, is independently selected from a group consisting of hydrogen, a halogen group, a cyano group, a nitro group, a hydroxyl group, an amide group, an ester group, a ketone group, a thioester group, a silyl group, a substituted or unsubstituted C.sub.1-C.sub.30 alkyl group, a substituted or unsubstituted C.sub.2-C.sub.30 alkenyl group, a substituted or unsubstituted C.sub.2-C.sub.30 alkynyl group, a substituted or unsubstituted C.sub.2-C.sub.50 heteroaryl group containing at least one of S, N, O, P and Si, a substituted or unsubstituted C.sub.3-C.sub.30 cycloalkyl group, a substituted or unsubstituted C.sub.3-C.sub.30 cycloalkenyl group, a substituted or unsubstituted C.sub.5-C.sub.50 aryl group, a substituted or unsubstituted C.sub.1-C.sub.30 alkoxy group, a substituted or unsubstituted C.sub.5-C.sub.50 aryloxy group, a substituted or unsubstituted C.sub.1-C.sub.30 alkylamino group, a substituted or unsubstituted C.sub.6-C.sub.30 arylamino group, a substituted or unsubstituted C.sub.1-C.sub.30 alkylsilyl group and a substituted or unsubstituted C.sub.5-C.sub.50 arylsilyl group.

9. The organic thin-film transistor according to claim 8, wherein the organic thin-film transistor has a top-contact or bottom-contact structure.

10. The organic thin-film transistor according to claim 8, wherein the gate electrode, the source electrode and the drain electrode are selected from a group consisting of gold, silver, aluminum, nickel, chromium and indium tin oxide.

11. The organic thin-film transistor according to claim 8, wherein the substrate is selected from a group consisting of glass, polyethylene naphthalate, polyethylene terephthalate, polycarbonate, polyvinyl alcohol, polyacrylate, polyimide, polynorbornene and polyethersulfone.

12. The organic thin-film transistor according to claim 8, wherein the insulating layer is selected from a group consisting of Ba.sub.0.33Sr.sub.0.66TiO.sub.3 (BST), Al.sub.2O.sub.3, Ta.sub.2O.sub.5, La.sub.2O.sub.5, Y.sub.2O.sub.3, TiO.sub.2, PdZr.sub.0.33Ti.sub.0.66O.sub.3 (PZT), Bi.sub.4Ti.sub.3O.sub.12, BaMgF.sub.4, SrBi.sub.2(TaNb).sub.2O, Ba(ZrTi)O.sub.3(BZT), BaTiO.sub.3, SrTiO.sub.3, Bi.sub.4Ti.sub.3O.sub.12, SiO.sub.2, SiN.sub.x, AlON, polyimide, BCB, parylene, polyacrylate, polyvinyl alcohol and polyvinylphenol.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a cross-sectional view showing the structure of an organic thin-film transistor including a conductive organic semiconductor compound according to the present disclosure.

(2) FIG. 2 shows the thermogravimetric analysis (TGA) result of a conductive organic semiconductor compound prepared in Synthesis Example 6 (PNDI2F3T) and a conductive organic semiconductor compound prepared in Synthesis Example 8 (PDPP2F3T).

(3) FIG. 3 shows the differential scanning calorimetry (DSC) result of a conductive organic semiconductor compound prepared in Synthesis Example 6 (PNDI2F3T) and a conductive organic semiconductor compound prepared in Synthesis Example 8 (PDPP2F3T).

(4) FIG. 4 shows the UV-vis absorption spectra of an organic semiconductor thin film prepared in Example 2 using a conductive organic semiconductor compound (PNDI2F3T, Synthesis Example 6) before and after annealing.

(5) FIG. 5 shows the UV-vis absorption spectra of an organic semiconductor thin film prepared in Example 2 using a conductive organic semiconductor compound (PDPP2F3T, Synthesis Example 8) before and after annealing.

(6) FIG. 6 shows the electrochemical properties of an organic semiconductor thin film prepared in Example 1 using a conductive organic semiconductor compound (PNDI2F3T, Synthesis Example 5 or 6) measured by cyclic voltammetry.

(7) FIG. 7 shows the electrochemical properties of an organic semiconductor thin film prepared in Example 1 using a conductive organic semiconductor compound (PDPP2F3T, Synthesis Example 7 or 8) measured by cyclic voltammetry.

(8) FIG. 8 shows the current-voltage (J-V) curve showing the electron mobility of an organic thin-film transistor prepared in Example 3 using a conductive organic semiconductor compound (PNDI2F3T, Synthesis Example 6). Gold was used as a top electrode of the organic thin-film transistor.

(9) FIG. 9 shows the current-voltage (J-V) curve showing the electron mobility of an organic thin-film transistor prepared in Example 3 using a conductive organic semiconductor compound (PNDI2F3T, Synthesis Example 6). Aluminum was used as a top electrode of the organic thin-film transistor.

(10) FIG. 10 shows the current-voltage (J-V) curve showing the electron mobility of an organic thin-film transistor prepared in Example 3 using a conductive organic semiconductor compound (PDPP2F3T, Synthesis Example 8). Gold was used as a top electrode of the organic thin-film transistor.

(11) FIG. 11 shows the current-voltage (J-V) curve showing the electron mobility of an organic thin-film transistor prepared in Example 3 using a conductive organic semiconductor compound (PDPP2F3T, Synthesis Example 8). Aluminum was used as a top electrode of the organic thin-film transistor.

DETAILED DESCRIPTION OF EMBODIMENTS

(12) Hereinafter, various aspects and exemplary embodiments of the present disclosure are described in further detail.

(13) In an aspect, the present disclosure provides a conductive organic semiconductor compound represented by [Chemical Formula I] or [Chemical Formula II]:

(14) ##STR00013##

(15) In [Chemical Formula I] and [Chemical Formula II], Ar is selected from [Structural Formula 1]:

(16) ##STR00014## ##STR00015## ##STR00016## ##STR00017## ##STR00018##

(17) In [Structural Formula 1],

(18) each of R.sub.1 and R.sub.2, which are identical or different, is independently selected from a group consisting of hydrogen, a halogen group, a cyano group, a nitro group, a hydroxyl group, an amide group, an ester group, a ketone group, a thioester group, a silyl group, a substituted or unsubstituted C.sub.1-C.sub.30 alkyl group, a substituted or unsubstituted C.sub.2-C.sub.30 alkenyl group, a substituted or unsubstituted C.sub.2-C.sub.30 alkynyl group, a substituted or unsubstituted C.sub.2-C.sub.50 heteroaryl group containing at least one of S, N, O, P and Si, a substituted or unsubstituted C.sub.3-C.sub.30 cycloalkyl group, a substituted or unsubstituted C.sub.3-C.sub.30 cycloalkenyl group, a substituted or unsubstituted C.sub.5-C.sub.50 aryl group, a substituted or unsubstituted C.sub.1-C.sub.30 alkoxy group, a substituted or unsubstituted C.sub.5-C.sub.50 aryloxy group, a substituted or unsubstituted C.sub.1-C.sub.30 alkylamino group, a substituted or unsubstituted C.sub.6-C.sub.30 arylamino group, a substituted or unsubstituted C.sub.1-C.sub.30 alkylsilyl group and a substituted or unsubstituted C.sub.5-C.sub.50 arylsilyl group, and

(19) n is an integer from 5 to 100,000.

(20) The conductive organic semiconductor compound represented by [Chemical Formula II] may be represented by [Chemical Formula III] or [Chemical Formula IV]:

(21) ##STR00019##

(22) In [Chemical Formula III] and [Chemical Formula IV],

(23) each of R.sub.3 and R.sub.4, which are identical or different, is independently selected from a group consisting of hydrogen, a halogen group, a cyano group, a nitro group, a hydroxyl group, an amide group, an ester group, a ketone group, a thioester group, a silyl group, a substituted or unsubstituted C.sub.1-C.sub.30 alkyl group, a substituted or unsubstituted C.sub.2-C.sub.30 alkenyl group, a substituted or unsubstituted C.sub.2-C.sub.30 alkynyl group, a substituted or unsubstituted C.sub.2-C.sub.50 heteroaryl group containing at least one of S, N, O, P and Si, a substituted or unsubstituted C.sub.3-C.sub.30 cycloalkyl group, a substituted or unsubstituted C.sub.3-C.sub.30 cycloalkenyl group, a substituted or unsubstituted C.sub.5-C.sub.50 aryl group, a substituted or unsubstituted C.sub.1-C.sub.30 alkoxy group, a substituted or unsubstituted C.sub.5-C.sub.50 aryloxy group, a substituted or unsubstituted C.sub.1-C.sub.30 alkylamino group, a substituted or unsubstituted C.sub.6-C.sub.30 arylamino group, a substituted or unsubstituted C.sub.1-C.sub.30 alkylsilyl group and a substituted or unsubstituted C.sub.5-C.sub.50 arylsilyl group, and

(24) n is an integer from 5 to 100,000.

(25) The conductive organic semiconductor compound represented by [Chemical Formula III] may be represented by [Chemical Formula V]:

(26) ##STR00020##

(27) In [Chemical Formula V], n is an integer from 5 to 100,000.

(28) The conductive organic semiconductor compound represented by [Chemical Formula IV] may be represented by [Chemical Formula VI]:

(29) ##STR00021##

(30) In [Chemical Formula VI], n is an integer from 5 to 100,000.

(31) Since the conductive organic semiconductor compound has a number average molecular weight (M.sub.n) of about 10,000-100,000, it can be controlled to have superior solubility for various organic solvents. Accordingly, it can be prepared into a thin film with superior crystallinity in various organic solvents.

(32) In particular, since the conductive organic semiconductor compound has high a repeat unit having a thiophene monomer and a dipyrrolopyrrole monomer with high hole mobility and superior light absorption ability and a dithienobenzodithiophene core with excellent hole conductivity, it has low band gap and exhibits high charge mobility and low cutoff current loss when used as an organic semiconductor of a transistor.

(33) The conductive organic semiconductor compound may have an electron mobility of 110.sup.6 cm.sup.2/V.Math.s or higher.

(34) Since the conductive organic semiconductor compound has a low band gap of 1.0-3.0 eV, it can be usefully used as a material for an organic optoelectric device selected from an organic photodiode, an organic light-emitting diode, an organic thin-film transistor and an organic solar cell.

(35) The conductive organic semiconductor compound may be an n-type organic semiconductor compound.

(36) In another aspect, the present disclosure provides a method for preparing a conductive organic semiconductor compound represented by [Chemical Formula I], including dissolving a compound represented by [Chemical Formula VII] and a compound represented by [Chemical Formula VIII] in a solvent and causing them to react by adding a palladium catalyst:

(37) ##STR00022##

(38) In [Chemical Formula I], [Chemical Formula VII] and [Chemical Formula VIII], X is a halogen selected from Cl, Br and I, Y is selected from R.sub.6R.sub.7R.sub.8SnCl and BO.sub.2R.sub.9R.sub.10, and n is an integer from 5 to 100,000.

(39) Each of R.sub.6, R.sub.7 and R.sub.8, which are identical or different, is hydrogen or a C.sub.1-C.sub.8 alkyl group, each of R.sub.9, R.sub.10, which are identical or different, is hydrogen or a C.sub.1-C.sub.8 alkyl group and the R.sub.9 and the R.sub.10 may be linked by a chemical bond.

(40) Ar is selected from [Structural Formula 1]:

(41) ##STR00023## ##STR00024## ##STR00025## ##STR00026## ##STR00027##

(42) In [Structural Formula 1],

(43) each of R.sub.1 and R.sub.2, which are identical or different, is independently selected from a group consisting of hydrogen, a halogen group, a cyano group, a nitro group, a hydroxyl group, an amide group, an ester group, a ketone group, a thioester group, a silyl group, a substituted or unsubstituted C.sub.1-C.sub.30 alkyl group, a substituted or unsubstituted C.sub.2-C.sub.30 alkenyl group, a substituted or unsubstituted C.sub.2-C.sub.30 alkynyl group, a substituted or unsubstituted C.sub.2-C.sub.50 heteroaryl group containing at least one of S, N, O, P and Si, a substituted or unsubstituted C.sub.3-C.sub.30 cycloalkyl group, a substituted or unsubstituted C.sub.3-C.sub.30 cycloalkenyl group, a substituted or unsubstituted C.sub.5-C.sub.50 aryl group, a substituted or unsubstituted C.sub.1-C.sub.30 alkoxy group, a substituted or unsubstituted C.sub.5-C.sub.50 aryloxy group, a substituted or unsubstituted C.sub.1-C.sub.30 alkylamino group, a substituted or unsubstituted C.sub.6-C.sub.30 arylamino group, a substituted or unsubstituted C.sub.1-C.sub.30 alkylsilyl group and a substituted or unsubstituted C.sub.5-C.sub.50 arylsilyl group, and

(44) n is an integer from 5 to 100,000.

(45) In another aspect, the present disclosure provides a method for preparing a conductive organic semiconductor compound represented by [Chemical Formula II], including dissolving a compound represented by [Chemical Formula VII] and a compound represented by [Chemical Formula IX] in a solvent and causing them to react by adding a palladium catalyst:

(46) ##STR00028##

(47) In [Chemical Formula II], [Chemical Formula VII] and [Chemical Formula IX], X is a halogen selected from Cl, Br and I, Y is selected from R.sub.6R.sub.7R.sub.8SnCl and BO.sub.2R.sub.9R.sub.10, and n is an integer from 5 to 100,000.

(48) Each of R.sub.6, R.sub.7 and R.sub.8, which are identical or different, is hydrogen or a C.sub.1-C.sub.8 alkyl group, each of R.sub.9, R.sub.10, which are identical or different, is hydrogen or a C.sub.1-C.sub.8 alkyl group and the R.sub.9 and the R.sub.10 may be linked by a chemical bond.

(49) Ar is the same as defined above in the description of the method for preparing a conductive organic semiconductor compound represented by [Chemical Formula I].

(50) In the methods for preparing a conductive organic semiconductor compound represented by [Chemical Formula I] and a conductive organic semiconductor compound represented by [Chemical Formula II], the palladium catalyst may be a palladium(0) catalyst such as tetrakis(triphenylphosphine)palladium(0) (Pd(PPh.sub.3).sub.4) or a palladium(II) catalyst such as 1,4-bis(triphenylphosphine)palladium(II) dichloride (PdCl.sub.2(PPh.sub.3).sub.2), [1,4-bis(diphenylphosphine)butane]palladium(II) dichloride (Pd(dppb)Cl.sub.2), [1,1-bis(diphenylphosphino)ferrocene]palladium(II) dichloride (Pd(dppf)Cl.sub.2) or palladium(II) acetate (Pd(OAc).sub.2).

(51) The content of the catalyst may be controlled depending on the monomers. For example, the tetrakis(triphenylphosphine)palladium compound may be used in an amount of 5-20 parts by weight based on 100 parts by weight of the monomer represented by [Chemical Formula VII].

(52) In the preparation method, the solvent may be one or more selected from a group consisting of toluene, dimethylformamide, methanol, hexane, tri(o-tolyl)phosphine, chlorobenzene, ethylene acetate, tetrahydrofuran and N-methylpyrrolidinone.

(53) The preparation method may be performed at 100-200 C. for 10-60 hours, more specifically at 100-140 C. for 20-40 hours.

(54) The conductive organic semiconductor compound may be prepared into an organic semiconductor thin film. The organic semiconductor thin film may be prepared by a method selected from vacuum deposition, screen printing, printing, spin coating, dipping and inkjet printing.

(55) Since the conductive organic semiconductor compound can be prepared into a thin film via a solution process, a large-area thin film can be prepared easily at low cost.

(56) FIG. 1 is a cross-sectional view showing the structure of an organic thin-film transistor including a conductive organic semiconductor compound according to the present disclosure.

(57) Referring to FIG. 1, the organic thin-film transistor 100 includes: a substrate 110; a gate electrode 120 formed on the substrate 110; an insulating layer 130 formed on the gate electrode 120; an organic semiconductor thin film 140 formed on the insulating layer 130; and a source electrode layer and a drain electrode layer 150a, 150b formed on the organic semiconductor thin film 140.

(58) The substrate 110 may be formed of an inorganic material, an organic material or a composite of an inorganic material and an organic material. Specifically, it may be selected from a group consisting of glass, polyethylene naphthalate, polyethylene terephthalate, polycarbonate, polyvinyl alcohol, polyacrylate, polyimide, polynorbornene and polyethersulfone, although not being limited thereto.

(59) The gate electrode 120 and the source electrode layer and the drain electrode layer 150a, 150b may be formed of a commonly used metal. Specifically, it may be selected from a group consisting of gold, silver, aluminum, nickel, chromium and indium tin oxide, although not being limited thereto.

(60) The insulating layer 130 may be formed of a commonly used insulator with a high dielectric constant. Specifically, it may be selected from a group consisting of ferroelectric insulator selected from a group consisting of Ba.sub.0.33Sr.sub.0.66TiO.sub.3 (BST), Al.sub.2O.sub.3, Ta.sub.2O.sub.5, La.sub.2O.sub.5, Y.sub.2O.sub.3 and TiO.sub.2, an inorganic insulator selected from a group consisting of PdZr.sub.0.33Ti.sub.0.66O.sub.3 (PZT), Bi.sub.4Ti.sub.3O.sub.12, BaMgF.sub.4, SrBi.sub.2(TaNb).sub.2O.sub.9, Ba(ZrTi)O.sub.3(BZT), BaTiO.sub.3, SrTiO.sub.3, Bi.sub.4Ti.sub.3O.sub.12, SiO.sub.2, SiN.sub.x and AlON, polyimide, BCB, parylene, polyacrylate, polyvinyl alcohol and polyvinylphenol, although not being limited thereto.

(61) Specifically, the organic semiconductor thin film 140 may be an organic semiconductor thin film prepared from the conductive organic semiconductor compound represented by [Chemical Formula I] or the conductive organic semiconductor compound represented by [Chemical Formula II] described above. A description about the conductive organic semiconductor compounds will be omitted since it is the same as above.

(62) Since the conductive organic semiconductor compound has excellent properties such as superior solubility and flexibility and low band gap, it can be used not only for the organic thin-film transistor but also for various memory devices, organic light-emitting diodes, photosensors, laser devices or photovoltaic devices such as an organic solar cell.

(63) In particular, an organic solar cell prepared using the conductive organic semiconductor compound is advantageous in that the quantum yield is about 4 times or higher than that of the existing solar cell and the process cost is much lower.

(64) Hereinafter, the present disclosure will be described in more detail through examples. However, the scope and content of the present disclosure cannot interpreted as being reduced or limited by the examples. In addition, it will be obvious that various changes and modifications can be easily made by those of ordinary skill in the art based on the present disclosure including the examples and that those changes and modifications are included in the scope of the appended claims.

EXAMPLES

Synthesis Examples. Synthesis of Conductive Organic Semiconductor Compound According to the Present Disclosure

(65) ##STR00029##

(66) ##STR00030## ##STR00031##

Synthesis Example 1: Synthesis of 2,5-dibromo-3,4-difluoro-thiophene (Chemical Formula 2)

(67) A compound of Chemical Formula 1 (2.28 g, 8.62 mmol) and dichloromethane (10 mL) were added to a 100-mL flask containing a magnetic stirring bar. After cooling to 0 C., bromine (0.97 mL, 18.96 mmol) was slowly added dropwise. After slowly raising temperature to 50 C., reaction was performed for 3 hours. Then, after removing the remaining bromine with sodium bisulfite, followed by extraction with dichloromethane, the organic layer was dehydrated with magnesium sulfate. After removing the solvent using a rotary evaporator, followed by purification by column chromatography (hexane), 2,5-dibromo-3,4-difluoro-thiophene (Chemical Formula 2) (1.5 g, 62.6%) was obtained.

(68) .sup.13C NMR (100 MHz, CDCl.sub.3): 90.33, 143.95.

Synthesis Example 2: Synthesis of 3,4-difluoro-2,5-bis-trimethylstannyl-thiophene (Chemical Formula 3)

(69) The compound of Chemical Formula 2 (1.22 g, 4.39 mmol) and anhydrous tetrahydrofuran (18 mL) were added to a 100-mL flask containing a magnetic stirring bar under argon atmosphere. After cooling to 78 C., 1.6 M n-butyllithium (5.77 mL, 9.23 mmol) was slowly added dropwise. After maintaining at 78 C. for 40 minutes, followed by addition of a trimethyltin chloride solution (21.98 mL, 21.98 mmol, 1 M), reaction was performed for 12 hours at room temperature with stirring. After extracting with water and diethyl ether, the organic layer was dehydrated with magnesium sulfate. After removing the solvent using a rotary evaporator, followed by recrystallization in methanol at low temperature, 3,4-difluoro-2,5-bis-trimethylstannyl-thiophene (Chemical Formula 3) (786.2 mg, 40.1%) was obtained.

(70) .sup.1H NMR (400 MHz, CDCl.sub.3): 0.39 (s, 12H).

Synthesis Example 3: Synthesis of N,N-bis(2-decyltetradecyl)-2,6-di(thiophen-2-yl)naphthalene-1,4,5,8-bis(dicarboximide) (Chemical Formula 5)

(71) The compound of Chemical Formula 4 (302.2 mg, 0.275 mmol), 2-tributylstannylthiophene (0.262 mL, 0.825 mmol) and tetrakis(triphenylphosphine)palladium(0) (Pd(PPh.sub.3).sub.4) (15.9 mg, 0.014 mmol) were added to a 10-mL flask containing a magnetic stirring bar. Then, degassed toluene (4.8 mL) and dimethylformamide (1.2 mL) were added as solvents. After performing reaction at 120 C. for about 12 hours, the reaction mixture was cooled to room temperature, diluted with dichloromethane and washed 3 times with water and brine. The organic layer was dehydrated with magnesium sulfate and the solvent was removed using a rotary evaporator. After separation by column chromatography (dichloromethane:hexane=1:1), N,N-bis(2-decyltetradecyl)-2,6-di(thiophen-2-yl)naphthalene-1,4,5,8-bis(dicarboximide) (Chemical Formula 5) (249.8 mg, 82.3%) was obtained.

(72) .sup.1H NMR (400 MHz, CDCl.sub.3): 0.82-0.89 (m, 12H), 1.10-1.45 (m, 80H), 1.83-2.10 (br, 2H), 4.07 (d, 4H), 7.20 (d, 2H), 7.31 (d, 2H), 7.60 (d, 2H), 8.75 (s, 2H).

Synthesis Example 4: Synthesis of N,N-bis(2-decyltetradecyl)-2,6-bis(5-bromothiophen-2-yl)naphthalene-1,4,5,8-bis(dicarboximide) (Chemical Formula 6)

(73) The compound of Chemical Formula 5 (249.8 mg, 0.226 mmol), chloroform (8 mL) and dimethylformamide (2 mL) were added to a 25-mL flask containing a magnetic stirring bar. Then, a solution of N-bromosuccinimide (NBS) (96.7 mg, 0.543 mmol) dissolved in chloroform (2 mL) and dimethylformamide (3 mL) was slowly added dropwise. After covering with aluminum foil to prevent exposure to light and performing reaction at room temperature for 2 days, the solvent was removed using a rotary evaporator. After separation by column chromatography (dichloromethane:hexane=1:2), N,N-bis(2-decyltetradecyl)-2,6-bis(5-bromothiophen-2-yl)naphthalene-1,4,5,8-bis(dicarboximide) (Chemical Formula 6) (205 mg, 71.9%) was obtained.

(74) .sup.1H NMR (400 MHz, CDCl.sub.3): 0.79-0.92 (m, 12H), 1.10-1.43 (m, 80H), 1.83-2.01 (m, 2H), 4.06 (d, 4H), 7.08 (d, 2H), 7.14 (d, 2H), 8.71 (s, 2H).

Synthesis Example 5: Synthesis of PNDI2F3T (Chemical Formula V) (Synthesis Method 1)

(75) The 3,4-difluoro-2,5-bis-trimethylstannyl-thiophene (Chemical Formula 3) (35.7 mg, 0.08 mmol) obtained in Synthesis Example 2, the N,N-bis(2-decyltetradecyl)-2,6-bis(5-bromothiophen-2-yl)naphthalene-1,4,5,8-bis(dicarboximide) (Chemical Formula 6) (101 mg, 0.08 mmol) obtained in Synthesis Example 4 and tetrakis(triphenylphosphine)palladium(0) (Pd(PPh.sub.3).sub.4) (3.9 mg, 3.44 mol) were added to a 5-mL flask containing a magnetic stirring bar. Then, degassed toluene (1.3 mL) and dimethylformamide (0.3 mL) were added as solvents. After performing reaction at 120 C. for about 36 hours, the reaction mixture was cooled to room temperature, reprecipitated in methanol (50 mL) and then filtered. The reaction mixture was Soxhlet extracted with hexane and methanol and then with chloroform. The extracted solution was passed through a celite filter and the solvent was removed using a rotary evaporator. After reprecipitation in methanol (50 mL), a polymer PNDI2F3T (Chemical Formula V) (62 mg, 63.5%) was obtained.

(76) GPC: M.sub.n=13.5 kg/mol; PDI=1.53.

Synthesis Example 6: Synthesis of PNDI2F3T (Chemical Formula V) (Synthesis Method 2)

(77) The 3,4-difluoro-2,5-bis-trimethylstannyl-thiophene (Chemical Formula 3) (35.5 mg, 0.08 mmol) obtained in Synthesis Example 2, the N,N-bis(2-decyltetradecyl)-2,6-bis(5-bromothiophen-2-yl)naphthalene-1,4,5,8-bis(dicarboximide) (Chemical Formula 6) (100.4 mg, 0.08 mmol) obtained in Synthesis Example 4, tris(dibenzylideneacetone)dipalladium(0) (Pd.sub.2[dba].sub.3) (1.5 mg, 1.6 mol) and tri(o-tolyl)phosphine (1.9 mg, 6.4 mol) were added to a 5-mL flask containing a magnetic stirring bar. Then, degassed chlorobenzene (1.6 mL) was added as a solvent. After performing reaction at 120 C. for about 36 hours, the reaction mixture was cooled to room temperature, reprecipitated in methanol (50 mL) and then filtered. The reaction mixture was Soxhlet extracted with hexane and methanol and then with chloroform. The extracted solution was passed through a celite filter and the solvent was removed using a rotary evaporator. After reprecipitation in methanol (50 mL), a polymer PNDI2F3T (Chemical Formula V) (82.5 mg, 85.0%) was obtained.

(78) GPC: M.sub.n=24.7 kg/mol; PDI=1.83.

Synthesis Example 7: Synthesis of PDPP2F3T (Chemical Formula VI) (Synthesis Method 1)

(79) The 3,4-difluoro-2,5-bis-trimethylstannyl-thiophene (Chemical Formula 3) (53.6 mg, 0.12 mmol) obtained in Synthesis Example 2, 3,6-bis(5-bromothiophen-2-yl)-2,5-bis(2-decyltetradecyl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (Chemical Formula 7) (136.1 mg, 0.12 mmol) and tetrakis(triphenylphosphine)palladium(0) (Pd(PPh.sub.3).sub.4) (6.0 mg, 5.17 mol) were added to a 5-mL flask containing a magnetic stirring bar. Then, degassed toluene (1.9 mL) and dimethylformamide (0.5 mL) were added as solvents. After performing reaction at 120 C. for about 36 hours, the reaction mixture was cooled to room temperature, reprecipitated in methanol (50 mL) and then filtered. The reaction mixture was Soxhlet extracted with methanol, acetone and ethylene acetate and then with chloroform. The extracted solution was passed through a celite filter and the solvent was removed using a rotary evaporator. After reprecipitation in methanol (50 mL), a polymer PDPP2F3T (Chemical Formula VI) (90 mg, 68.8%) was obtained.

(80) GPC: M.sub.n=26.8 kg/mol; PDI=2.98.

Synthesis Example 8: Synthesis of PDPP2F3T (Chemical Formula VI) (Synthesis Method 2)

(81) The 3,4-difluoro-2,5-bis-trimethylstannyl-thiophene (Chemical Formula 3) (50.8 mg, 0.114 mmol) obtained in Synthesis Example 2, 3,6-bis(5-bromothiophen-2-yl)-2,5-bis(2-decyltetradecyl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (Chemical Formula 7) (129.0 mg, 0.114 mmol), tris(dibenzylideneacetone)dipalladium(0) (Pd.sub.2[dba].sub.3) (2.1 mg, 2.3 mol) and tri(o-tolyl)phosphine (2.8 mg, 9.1 mol) were added to a 5-mL flask containing a magnetic stirring bar. Then, degassed chlorobenzene (2.3 mL) was added as a solvent. After performing reaction at 120 C. for about 36 hours, the reaction mixture was cooled to room temperature, reprecipitated in methanol (50 mL) and then filtered. The reaction mixture was Soxhlet extracted with methanol and ethylene acetate and then with chloroform. The extracted solution was passed through a celite filter and the solvent was removed using a rotary evaporator. After reprecipitation in methanol (50 mL), a polymer PDPP2F3T (Chemical Formula VI) (108.9 mg, 87.7%) was obtained.

(82) GPC: M.sub.n=39.8 kg/mol; PDI=2.76.

Example 1. Preparation of Organic Semiconductor Thin Film

(83) A glass substrate was prepared by drying after washing in isopropyl alcohol for 10 minutes, in acetone for 10 minutes and then in isopropyl alcohol for 10 minutes.

(84) Then, a solution obtained by dissolving the conductive organic semiconductor compound (10 mg) prepared in Synthesis Example 5, 6, 7 or 8 in 1 mL of chlorobenzene was spin coated on the glass substrate at 1000 rpm to obtain each organic semiconductor thin film. Subsequently, the thin film was annealed at 200 C.

Example 2. Analysis of Electrical Properties of Conductive Organic Semiconductor Material

(85) The electrochemical properties of the organic semiconductor thin film prepared in Example 1 was analyzed by cyclic voltammetry and its energy level was calculated.

(86) Cyclic voltammetry measurement was made as follows. First, the organic semiconductor thin film (Example 1) coated on a carbon glass electrode was prepared as a working electrode, a platinum wire was prepared as a counter electrode and Ag/Ag.sup.+ was prepared as a reference electrode. A voltage was applied to the reference electrode (Ag/Ag.sup.+) using a potentiometer and the current flowing as a result of redox reaction of the analyte below the working electrode was measured at the counter electrode. The measured current was corrected for redox potential measurement using ferrocene/ferrocenium (Fc/Fc.sup.+) under the same condition. The redox potential of ferrocene/ferrocenium (Fc/Fc.sup.+) was 0.09 eV higher than that of the Ag/Ag.sup.+ electrode. The voltage when oxidation started ((pox) and the voltage (.sub.red) when reduction started were measured and the highest occupied molecular orbital (HOMO) energy level and the lowest unoccupied molecular orbital (LUMO) energy level were calculated according to Equation 1.
E.sub.HOMO=4.8(.sub.OX0.09) (eV)
E.sub.LUMO=4.8(.sub.red0.09) (eV)Equation 1

Example 3. Fabrication of Organic Thin-Film Transistor Using Conductive Organic Semiconductor Material

(87) A transistor having a top-contact structure was fabricated using the conductive organic semiconductor compounds synthesized in Synthesis Examples 6 and 8 (PNDI2F3T, PDPP2F3T). The structure is shown in detail in FIG. 1.

(88) To fabricate the transistor, first, a 300-nm thick silicon oxide film was formed on a heavily p-doped silicon gate electrode as insulating layer. Subsequently, a 20-nm thick Cytop thin film was formed on the insulating layer by spin coating and then a zirconium oxide film was formed by spin coating a solution of zirconium(IV) acetylacetonate (Zr(acac).sub.4) dissolved in DMF via a sol-gel process. After annealing at 200 C. for an hour, a 40-nm thick polymer thin film was formed by spin coating a 0.2 wt % solution of the polymer dissolved in chloroform. Then, gold or aluminum was deposited to a thickness of 60 nm to form source and drain electrodes.

Test Example 1. Thermal Properties of Conductive Organic Semiconductor Compound

(89) FIG. 2 shows the thermogravimetric analysis (TGA) result of the conductive organic semiconductor compound prepared in Synthesis Example 6 (PNDI2F3T) and the conductive organic semiconductor compound prepared in Synthesis Example 8 (PDPP2F3T). And, FIG. 3 shows the differential scanning calorimetry (DSC) result of the conductive organic semiconductor compound prepared in Synthesis Example 6 (PNDI2F3T) and the conductive organic semiconductor compound prepared in Synthesis Example 8 (PDPP2F3T).

(90) As seen from FIG. 2 and FIG. 3, the conductive organic semiconductor compounds according to the present disclosure have superior thermal stability with high glass transition temperatures (T.sub.g) above 400 C. (initial decomposition temperatures: 418 C. and 457 C., respectively). Accordingly, they can exhibit long life time when used as materials for an organic optoelectric device and can exhibit superior process stability when thermal deposition is necessary.

Test Example 2. Optical Properties of Conductive Organic Semiconductor Compound

(91) FIG. 4 shows the UV-vis absorption spectra of the organic semiconductor thin film prepared in Example 2 using the conductive organic semiconductor compound (PNDI2F3T, Synthesis Example 6) before and after annealing. And, FIG. 5 shows the UV-vis absorption spectra of the organic semiconductor thin film prepared in Example 2 using the conductive organic semiconductor compound (PDPP2F3T, Synthesis Example 8) before and after annealing. In FIG. 4 and FIG. 5, the organic semiconductor thin film before the annealing was denoted as pristine film and the organic semiconductor thin film after the annealing was denoted as annealed film.

(92) The maximum absorption wavelength (.sub.max), onset absorption wavelength (.sub.onset) and optical band gap (E.sub.g,opt) of the organic semiconductor thin film prepared in Example 2 using the conductive organic semiconductor compound (PNDI2F3T, Synthesis Example 6; PDPP2F3T, Synthesis Example 8) measured after the annealing are described in [Table 1].

(93) TABLE-US-00001 TABLE 1 Maximum absorption Onset absorption Optical band wavelength (.sub.max) wavelength (.sub.onset) gap (E.sub.g,opt) PNDI2F3T 407, 680 nm 829 nm 1.50 eV (Synthesis Example 6) PDPP2F3T 850 nm 940 nm 1.32 eV (Synthesis Example 8)

(94) As seen from FIG. 4, FIG. 5 and Table 1, the organic semiconductor thin films prepared from the conductive organic semiconductor compounds according to the present disclosure had low band gaps required for organic solar cells. This suggests that the conductive organic semiconductor compound of the present disclosure can be used to prepare a high-efficiency organic solar cell.

Test Example 3. Characteristics of Organic Thin-Film Transistor

(95) After measuring the drain voltage-drain current vs. gate voltage and the gate voltage-drain current vs. drain voltage using the Keithley 2400 source/measure units, the characteristics of the fabricated device in the saturation regime were evaluated according to the following equation.

(96) $\begin{array}{cc}{I}_{ds}=\frac{W{C}_i}{2L}{\left(V_{gs}-V_T\right)}^2& \mathrm{Equation}2\end{array}$

(97) In Equation 2, VT is the threshold voltage, V.sub.gs is the applied gate voltage, is the field-effect charge mobility, W and L are the channel width and length, and C is the capacitance of the insulating layer. The threshold voltage is determined by the gate voltage when I.sub.ds is 0 from the graph of {square root over (I.sub.ds)} vs. V.sub.gs, and the field-effect charge mobility is calculated from the slope of the {square root over (I.sub.ds)} vs. V.sub.gs curve.

(98) FIGS. 8 and 9 show the current-voltage (J-V) curves showing the electron mobility of the organic thin-film transistors prepared in Example 3 using the conductive organic semiconductor compound (PNDI2F3T, Synthesis Example 6). Gold or aluminum was used as the top electrode of the organic thin-film transistors, respectively.

(99) FIGS. 10 and 11 show the current-voltage (J-V) curves showing the electron mobility of the organic thin-film transistors prepared in Example 3 using the conductive organic semiconductor compound (PDPP2F3T, Synthesis Example 8). Gold or aluminum was used as the top electrode of the organic thin-film transistors, respectively.

(100) The performance of the organic thin-film transistors is described in more detail in Table 2.

(101) TABLE-US-00002 TABLE 2 Mobility Condition (cm.sup.2/Vs) I.sub.on/off PNDI2F3T (Synthesis Au electrode 0.19 Example 6) Al electrode 0.25 PDPP2F3T (Synthesis Au electrode 0.1 Example 8) Al electrode 0.13 Existing transistor Adv. Funct. Mater. 2013, 0.01 [Comparative 24, 1151-1162 Example 1] Existing transistor Adv. Funct. Mater. 2013, 6.5 10.sup.4 [Comparative 24, 1151-1162 Example 2] Existing transistor Chem. Mater., 2013, 25, 0.05 10.sup.4-10.sup.5 [Comparative 2178-2183 Example 3]

(102) As seen from Table 2, the transistors using the organic semiconductor thin films (i.e., the conductive organic semiconductor compounds) of the present disclosure exhibit significantly improved performance as compared to the transistors using the existing conductive organic semiconductor compounds. For example, the polymers wherein fluorine-free thiophene was introduced instead of difluorothiophene to the PNDI2F3T (Synthesis Example 6) of the present disclosure (Comparative Example 1 and Comparative Example 2) showed charge mobility of 0.01 cm.sup.2/Vs and 6.510.sup.4 cm.sup.2/Vs, and the polymer wherein 2,1,3-benzothiadiazole was introduced instead of difluorothiophene showed charge mobility of 0.05 cm.sup.2/Vs. In contrast, the polymer organic semiconductors according to the present disclosure showed 4 to tens of times increased charge mobility.