Organic compound, and organic thin film and electronic device

An organic compound is represented by Chemical Formula 1, and an organic thin film, an organic thin film transistor, and an electronic device include the organic compound.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2014-0100632 filed in the Korean Intellectual Property Office on Aug. 5, 2014, the entire contents of which are incorporated herein by reference.

BACKGROUND

Example embodiments provide an organic compound, an organic thin film, and an electronic device.

2. Description of the Related Art

A flat panel display (e.g., a liquid crystal display (LCD), an organic light emitting diode (OLED) display, or an electrophoretic display) includes multiple pairs of field generating electrodes and an electro-optical active layer interposed therebetween.

The liquid crystal display (LCD) includes an electro-optical active layer of a liquid crystal layer, and the organic light emitting diode (OLED) display includes an electro-optical active layer of an organic emission layer.

One of paired field generating electrodes are generally connected to a switch and applied with an electrical signal, and the electro-optical active layer transforms the electrical signal to an optical signal to display an image.

The flat panel display includes a three-terminal element of a thin film transistor (TFT) as a switch. The flat panel display also includes a gate line transferring a scan signal for controlling the thin film transistor and a data line transferring a data signal to be applied to a pixel electrode.

Among the thin film transistors, an organic thin film transistor (OTFT) including an organic semiconductor (e.g., a low molecular compound or a polymer) instead of the inorganic semiconductor (e.g., silicon (Si)) has been actively researched.

The organic thin film transistor may be shaped in a fiber or a film formed according to the organic material characteristic, thereby drawing attention as a core element for a flexible display device.

The organic thin film transistor may be manufactured using a solution process (e.g., inkjet printing), and may be more easily applied to a large area flat panel display where a deposition process has a limit.

SUMMARY

Example embodiments provide an organic compound that is applicable to an electronic device, for example, an organic thin film transistor.

Example embodiments also provide an organic thin film including the organic compound.

Example embodiments also provide an electronic device including the organic thin film.

According to example embodiments, an organic compound is represented by the following Chemical Formula 1.
A-L-B  [Chemical Formula 1]

In Chemical Formula 1,

L is one of a substituted or unsubstituted C6to C30arylene group, a divalent substituted or unsubstituted C2to C30heterocyclic group, a substituted or unsubstituted C2to C20alkenylene group, a substituted or unsubstituted C2to C20alkynylene group, a substituted or unsubstituted C2to C20heteroalkylene group, an oxygen atom (O), a sulfur atom (S), a selenium atom (Se), a tellurium atom (Te), and a combination thereof, and

each of an A moiety and a B moiety are independently a condensed polycyclic group having four or more fused rings, and are represented by one of the Chemical Formulae 2 to 4,

wherein, in Chemical Formulae 2 to 4,

each of Ar1to Ar5are independently one of a substituted or unsubstituted 5-membered ring and a substituted or unsubstituted 6-membered ring,

at least one of Ar3to Ar5is a substituted or unsubstituted 5-membered ring having a heteroatom,

each of Ar1and Ar2forms a fused ring with an adjacent ring,

each of Ar3to Ar5forms a fused ring with an adjacent ring,

each of R1to R4and Raare independently one of hydrogen, a substituted or unsubstituted C1to C30alkyl group, a substituted or unsubstituted C3to C30cycloalkyl group, a substituted or unsubstituted C6to C30aryl group, a substituted or unsubstituted C7to C30arylalkyl group, a substituted or unsubstituted C1to C30heteroalkyl group, a substituted or unsubstituted C2to C30heterocycloalkyl group, a substituted or unsubstituted C2to C30heterocyclic group, a substituted or unsubstituted C2to C30alkenyl group, a substituted or unsubstituted C2to C30alkynyl group, a hydroxy group, a halogen atom, and a combination thereof,

each of a to f are independently integers ranging from 1 to 3, and

* indicates a linking point.

Each of the Ar1to Ar5may independently be one of a substituted or unsubstituted benzene ring and a substituted or unsubstituted heterocyclic group.

The at least one of the Ar1and Ar2may be a heterocyclic group including one of O, S, Se, Te, and NRa, and at least one of the Ar3to Ar5may be a heterocyclic group including one of O, S, Se, Te, and NRa, wherein Rais one of hydrogen, a substituted or unsubstituted C1to C30alkyl group, a substituted or unsubstituted C3to C30cycloalkyl group, a substituted or unsubstituted C6to C30aryl group, a substituted or unsubstituted C7to C30arylalkyl group, a substituted or unsubstituted C1to C30heteroalkyl group, a substituted or unsubstituted C2to C30heterocycloalkyl group, a substituted or unsubstituted C2to C30heterocyclic group, a substituted or unsubstituted C2to C30alkenyl group, a substituted or unsubstituted C2to C30alkynyl group, a hydroxy group, a halogen atom, and a combination thereof.

The Ar1and Ar2of Chemical Formula 2 or 3 may be different, and one of Ar3to Ar5of Chemical Formula 4 may be different from the others.

One of the Ar1and Ar2of Chemical Formula 2 or 3 may be a substituted or unsubstituted benzene ring, and the other of the Ar1and Ar2may be a substituted or unsubstituted heterocyclic group.

The Ar3and Ar4of Chemical Formula 4 may be a substituted or unsubstituted heterocyclic group and the Ar5may be a substituted or unsubstituted benzene ring.

The Ar4and Ar5of Chemical Formula 4 may be a substituted or unsubstituted heterocyclic group and the Ar3may be a substituted or unsubstituted benzene ring.

The Ar3and Ar5of Chemical Formula 4 may be a substituted or unsubstituted heterocyclic group and the Ar4may be a substituted or unsubstituted benzene ring.

Each of the A moiety and the B moiety may independently be one of the groups listed in the Group 1.

In Group 1,

each of R1to R9and Raare independently one of hydrogen, a substituted or unsubstituted C1to C30alkyl group, a substituted or unsubstituted C3to C30cycloalkyl group, a substituted or unsubstituted C6to C30aryl group, a substituted or unsubstituted C7to C30arylalkyl group, a substituted or unsubstituted C1to C30heteroalkyl group, a substituted orunsubstituted C2to C30heterocycloalkyl group, a substituted or unsubstituted C2to C30heterocyclic group, a substituted or unsubstituted C2to C30alkenyl group, a substituted or unsubstituted C2to C30alkynyl group, a hydroxy group, a halogen atom, and a combination thereof, and

* indicates a linking point.

The organic compound may be represented by one of the Chemical Formulae 5 to 37.

In Chemical Formulae 5 to 37,

Y is one of O, S, Se, and Te, and

each of R1to R13and Raare independently one of hydrogen, a substituted or unsubstituted C1to C30alkyl group, a substituted or unsubstituted C3to C30cycloalkyl group, a substituted or unsubstituted C6to C30aryl group, a substituted or unsubstituted C7to C30arylalkyl group, a substituted or unsubstituted C1to C30heteroalkyl group, a substituted or unsubstituted C2to C30heterocycloalkyl group, a substituted or unsubstituted C2to C30heterocyclic group, a substituted or unsubstituted C2to C30alkenyl group, a substituted or unsubstituted C2to C30alkynyl group, a hydroxy group, a halogen atom, and a combination thereof.

Each of the R10to R13may independently be one of hydrogen and a halogen atom.

According to example embodiments, an organic thin film includes the organic compound.

According to example embodiments, an electronic device includes the organic thin film.

According to example embodiments, an organic thin film transistor includes a gate electrode, an organic semiconductor overlapping the gate electrode, and a source electrode and a drain electrode electrically connected to the organic semiconductor, wherein the organic semiconductor includes an organic compound represented by the Chemical Formula 1.

According to example embodiments, an electronic device includes the organic thin film transistor.

The electronic device may include a solar cell, a liquid crystal display (LCD), an organic light emitting diode (OLED) display, an electrophoretic display device, an organic photoelectric device, and an organic sensor.

According to example embodiments, an electronic device includes the organic thin film.

DETAILED DESCRIPTION

Example embodiments will hereinafter be described in detail, and may be more easily performed by those who have common knowledge in the related art. However, this disclosure may be embodied in many different forms and is not to be construed as limited to the example embodiments set forth herein.

In the drawing, parts having no relationship with the description are omitted for clarity of the embodiments, and the same or similar constituent elements are indicated by the same reference numerals throughout the specification.

As used herein, when a definition is not otherwise provided, the term “substituted” refers to one substituted with a substituent selected from a halogen atom (F, Br, Cl, or I), a hydroxy group, an alkoxy group, a nitro group, a cyano group, an amino group, an azido group, an amidino group, a hydrazino group, a hydrazono group, a carbonyl group, a carbamyl group, a thiol group, an ester group, a carboxyl group or a salt thereof, a sulfonic acid group or a salt thereof, phosphoric acid or a salt thereof, a C1to C20alkyl group, a C2to C20alkenyl group, a C2to C20alkynyl group, a C6to C30aryl group, a C7to C30arylalkyl group, a C1to C30alkoxy group, a C1to C20heteroalkyl group, a C3to C20heteroarylalkyl group, a C3to C30cycloalkyl group, a C3to C15cycloalkenyl group, a C6to C15cycloalkynyl group, a C3to C30heterocycloalkyl group, and a combination thereof, instead of hydrogen of a compound.

As used herein, when a definition is not otherwise provided, the term “hetero” refers to one including 1 to 3 heteroatoms selected from N, O, S, Se, and P.

Hereinafter, an organic compound according to example embodiments is described.

An organic compound according to example embodiments is represented by the Chemical Formula 1.
A-L-B  [Chemical Formula 1]

In Chemical Formula 1,

L is one of a substituted or unsubstituted C6to C30arylene group, a divalent substituted or unsubstituted C2to C30heterocyclic group, a substituted or unsubstituted C2to C20alkenylene group, a substituted or unsubstituted C2to C20alkynylene group, a substituted or unsubstituted C2to C20heteroalkylene group, an oxygen atom (O), a sulfur atom (S), a selenium atom (Se), a tellurium atom (Te), and a combination thereof, and

each of an A moiety and a B moiety are independently a condensed polycyclic group including four or more fused rings, and are represented by one of the Chemical Formulae 2 to 4.

In Chemical Formulae 2 to 4,

each of Ar1to Ar5are independently one of a substituted or unsubstituted 5-membered ring and a substituted or unsubstituted 6-membered ring,

at least one of Ar3to Ar5is a substituted or unsubstituted 5-membered ring having a heteroatom,

each of Ar1and Ar2forms a fused ring with an adjacent ring,

each of Ar3to Ar5forms a fused ring with an adjacent ring,

each of X1and X2are independently one of O, S, Se, Te and NRa,

each of R1to R4and Raare independently one of hydrogen, a substituted or unsubstituted C1to C30alkyl group, a substituted or unsubstituted C3to C30cycloalkyl group, a substituted or unsubstituted C6to C30aryl group, a substituted or unsubstituted C7to C30arylalkyl group, a substituted or unsubstituted C1to C30heteroalkyl group, a substituted or unsubstituted C2to C30heterocycloalkyl group, a substituted or unsubstituted C2to C30heterocyclic group, a substituted or unsubstituted C2to C30alkenyl group, a substituted or unsubstituted C2to C30alkynyl group, a hydroxy group, a halogen atom, and a combination thereof,

each of a to f are independently integers ranging from 1 to 3, and

* indicates a linking point.

The organic compound is a low molecular compound where an A moiety of a condensed polycyclic group including four or more fused rings and a B moiety of a condensed polycyclic group including four or more fused rings are linked to each other through a linking group (L).

The organic compounds may increase charge mobility by appropriately adjusting the number of rings in the polycyclic groups and thereby increasing planarization properties of the organic compound and packing and stacking properties among the compounds. The organic compound may increase charge mobility by linking the two condensed polycyclic groups through an arylene group, a divalent multiple bonding group, and/or a divalent heteroatom-containing group and thereby increasing an orbital overlap among compounds.

Herein, the A moiety and the B moiety may not be positioned on the same plane but may be twisted with a predetermined or given angle.

An organic compound having a structure in which the A moiety and the B moiety are linked to an arylene group, a divalent multiple bonding group, and/or a divalent heteroatom-containing group may be easily synthesized and highly dissolved as well as maintain an overlap among compounds, compared with a compound having a structure in which the A moiety and the B moiety are fused to each other. Accordingly, a yield of the organic compound may be increased and may be easily applied to a solution process during formation of an organic thin film. As a result, the organic compound may increase processability of an electronic device as well as improve its electrical characteristics.

Each of the A moiety and the B moiety is a fused ring of a substituted or unsubstituted benzene ring and a substituted or unsubstituted heterocyclic group.

At least one of the Ar1and Ar2of Chemical Formula 2 or 3 may be a heterocyclic group including one of O, S, Se, Te and NRa, and at least one of Ar3to Ar5of Chemical Formula 4 may be a heterocyclic group including one of O, S, Se, Te and NRa. Herein, Ramay be one of hydrogen, a substituted or unsubstituted C1to C30alkyl group, a substituted or unsubstituted C3to C30cycloalkyl group, a substituted or unsubstituted C6to C30aryl group, a substituted or unsubstituted C7to C30arylalkyl group, a substituted or unsubstituted C1to C30heteroalkyl group, a substituted or unsubstituted C2to C30heterocycloalkyl group, a substituted or unsubstituted C2to C30heterocyclic group, a substituted or unsubstituted C2to C30alkenyl group, a substituted or unsubstituted C2to C30alkynyl group, a hydroxy group, a halogen atom, and a combination thereof.

For example, the Ar1and Ar2of Chemical Formula 2 or 3 may be different, and for example at least one of Ar1and Ar2may be a substituted or unsubstituted benzene ring, and the other one may be a substituted or unsubstituted heterocyclic group.

For example, one of Ar3to Ar5of Chemical Formula 4 may be different from the others. For example, Ar3and Ar4may be the same and may be different from Ar5, wherein Ar3and Ar4may be a substituted or unsubstituted heterocyclic group, and Ar5may be a substituted or unsubstituted benzene ring. For example, Ar4and Ar5may be the same and may be different from Ar3, wherein Ar4and Ar5may be a substituted or unsubstituted benzene ring, and A3may be a substituted or unsubstituted heterocyclic group. For example, Ar3and Ar5may be the same and may be different from Ar4, wherein Ar3and Ar5may be a substituted or unsubstituted benzene ring, and Ar4may be a substituted or unsubstituted heterocyclic group, or Ar3and Ar5may be a substituted or unsubstituted heterocyclic group, and Ar4may be a substituted or unsubstituted benzene ring.

For example, L of Chemical Formula 1 may be one of a substituted or unsubstituted C6to C30arylene group, a divalent substituted or unsubstituted C2to C30heterocyclic group, a substituted or unsubstituted C2to C20alkenylene group, a substituted or unsubstituted C2to C20heteroalkylene group, and a combination thereof. The substituted C6to C30arylene group may be, for example, substituted with one of an alkyl group, a halogen atom, and a combination thereof. The halogen atom may be, for example, fluorine.

The A moiety and the B moiety may be the same or different.

Each of the A moiety and the B moiety may independently be, for example, one of the groups listed in the Group 1, but are not limited thereto.

In Group 1,

each of X1to X4are independently one of O, S, Se, Te and NRa,

each of R1to R9and Raare independently one of hydrogen, a substituted or unsubstituted C1to C30alkyl group, a substituted or unsubstituted C3to C30cycloalkyl group, a substituted or unsubstituted C6to C30aryl group, a substituted or unsubstituted C7to C30arylalkyl group, a substituted or unsubstituted C1to C30heteroalkyl group, a substituted or unsubstituted C2to C30heterocycloalkyl group, a substituted or unsubstituted C2to C30heterocyclic group, a substituted or unsubstituted C2to C30alkenyl group, a substituted or unsubstituted C2to C30alkynyl group, a hydroxy group, a halogen atom, and a combination thereof, and

* indicates a linking point.

The organic compound may be, for example, represented by one of the Chemical Formulae 5 to 37, but is not limited thereto.

In Chemical Formulae 5 to 37,

each of X1to X4are independently one of O, S, Se, Te and NRa,

Y is one of O, S, Se and Te, and

each of R1to R13and Raare independently one of hydrogen, a substituted or unsubstituted C1to C30alkyl group, a substituted or unsubstituted C3to C30cycloalkyl group, a substituted or unsubstituted C6to C30aryl group, a substituted or unsubstituted C7to C30arylalkyl group, a substituted or unsubstituted C1to C30heteroalkyl group, a substituted or unsubstituted C2to C30heterocycloalkyl group, a substituted or unsubstituted C2to C30heterocyclic group, a substituted or unsubstituted C2to C30alkenyl group, a substituted or unsubstituted C2to C30alkynyl group, a hydroxy group, a halogen atom and a combination thereof.

For example, each of R10to R13of Chemical Formulae 5 to 15 may independently be one of hydrogen and a halogen atom. For example, R10to R13of Chemical Formulae 5 to 15 may all be hydrogen, or may include one to four halogen atoms. The halogen atom may be, for example, fluorine.

For example, each of X1to X4of Chemical Formulae 5 to 37 may independently be sulfur (S).

For example, Y of Chemical Formulae 27 to 37 may be oxygen (O) or sulfur (S).

For example, each of R1to R9of Chemical Formulae 5 to 37 may independently be hydrogen.

The organic compound may be formed into an organic thin film by a deposition or solution process. The organic thin film may be applied to various devices including an organic semiconductor. For example, the organic compound may be applied to an organic thin film transistor, and may be applied to a charge transport layer and/or an active layer of an electronic device (e.g., a solar cell, a liquid crystal display (LCD), an organic light emitting diode (OLED) display, an electrophoretic display, an organic photoelectric device, and an organic sensor).

Hereinafter, one example of an organic thin film transistor including the organic compound is described referring to the drawing.

A cross-sectional view of an organic thin film transistor according to example embodiments is shown.

A gate electrode124is formed on a substrate110made of transparent glass, silicon, or plastic. The gate electrode124is connected to a gate line (not shown) transferring a gate signal. The gate electrode124may be made of one of gold (Au), copper (Cu), nickel (Ni), aluminum (Al), molybdenum (Mo), chromium (Cr), tantalum (Ta), titanium (Ti), an alloy thereof, and a combination thereof.

A gate insulating layer140is formed on the gate electrode124. The gate insulating layer140may be made of an organic material or an inorganic material. Examples of the organic material may include a soluble polymer compound, for example, a polyvinyl alcohol-based compound, a polyimide-based compound, a polyacryl-based compound, a polystyrene-based compound, and benzocyclobutane (BCB), and examples of the inorganic material may include a silicon nitride (SiNx) and a silicon oxide (SiOx).

A source electrode173and a drain electrode175are formed on the gate insulating layer140. The source electrode173and the drain electrode175face each other with the gate electrode124therebetween. The source electrode173is electrically connected to the data line (not shown) transferring the data signal. The source electrode173and the drain electrode175may include at least one metal selected from gold (Au), copper (Cu), nickel (Ni), aluminum (Al), molybdenum (Mo), chromium (Cr), tantalum (Ta), titanium (Ti), an alloy thereof, or a combination thereof.

An organic semiconductor154is formed on the source electrode173and the drain electrode175. The organic semiconductor154may be made of the organic compound. The organic semiconductor154may be formed in a solution process (e.g., spin coating, slit coating, or inkjet printing) by preparing the above organic semiconductor as a solution. However, the organic compound may be formed using a dry process (e.g., deposition).

Although the bottom gate structured organic thin film transistor is illustrated as an organic thin film transistor, it is not limited thereto, and it may be applied to all organic thin film transistors (e.g., a top gate structured organic thin film transistor).

The organic thin film transistor may be applied to a switch or driving device of various electronic devices, and the electronic device may be, for example, a liquid crystal display (LCD), an organic light emitting diode (OLED) display, an electrophoretic display device, or an organic sensor.

Hereinafter, the present disclosure is illustrated in more detail with reference to examples. However, these are examples, and the present disclosure is not limited thereto.

Synthesis of Organic Compound

Synthesis Example 1

1. Synthesis of Compound 1

7.94 g (0.057 mol) of K2CO3is put in a 3-necked flask under a nitrogen atmosphere, and then 60 ml of distilled water and 100 ml of THF are subsequently added thereto. Then, 6.66 g (0.02 mol) of 3-(methylthio)-2,3-dihydronaphthalen-2-yl trifluoromethane sulfonate and 2.61 g (0.008 mol) of [1,1′:4′,1″-terphenyl]-4,4″-diyldiboronic acid are added to the solution, 1.42 g (0.00123 mol) of tetrakis(triphenylphosphine) palladium (0) is added thereto, and the resulting mixture is refluxed. Five hours later, a 1N HCl solution is added thereto to complete the reaction, and the reactant is extracted with ethyl acetate. The resultant is dried with MgSO4, and a solvent is removed, obtaining the compound 1. The obtained solid is washed several times with ether, obtaining 2 g of a yellow solid. The yield is 57%.

2. Synthesis of Compound 2

2 g (0.00348 mol) of the compound 1 is suspended in 200 ml of acetic acid, and then 0.83 g (0.0073 mol) of a 30% H2O2solution is slowly added thereto. Subsequently, the mixture is heated at 40° C. and agitated for 48 hours, and then acetic acid is removed, obtaining 1 g of a yellow solid compound 2.

The compound 2 is added to 10 ml of trifluoromethane sulfonic acid, the mixture is agitated for 24 hours, 90 ml of a solution of H2O/pyridine mixed in a ratio of 8:1 solution is added thereto, and the resulting mixture is refluxed for 30 minutes. The produced solid is filtered, obtaining 0.5 g of an orange solid compound 3.

Manufacture of Organic Thin Film Transistor

First, a silicon wafer substrate coated with the SiO2to be 3000 Å thick is exposed to O2plasma, and then dipped in an octadecyl trichlorosilane solution diluted in hexane to a concentration of 10 mM to change the surface to be hydrophobic. Subsequently, the organic compound according to Synthesis Example 1 is vacuum-vapor deposited to be 700 Å thick by heating the substrate from room temperature to 200° C. Subsequently, source and drain electrodes are formed thereon by using a shadow mask and depositing Au to be 1000 Å thick, manufacturing an organic thin film transistor.

Evaluation

Charge mobility and current on/off ratio (Ion/Ioff) of the organic thin film transistor according to Example 1 are calculated.

The charge mobility of the organic thin film transistor is obtained by obtaining a graph having (ISD)1/2and VGas variables from a saturation region current formula and a slope in the graph.

In the equations, ISDis a source-drain current, μ or μFETis charge mobility, C0is electrostatic capacity of a gate insulating layer, W is a channel width, L is a channel length, VGis a gate voltage, and VTis a threshold voltage.

A cut-off leakage current (Ioff) is a current flowing in an off state, and obtained as a minimum current in an off state. A current on-off ratio (Ion/Ioff) is obtained as a ratio of a maximum current in an on state relative to a minimum current in the off state.

The results are shown in Table 1.

Referring to Table 1, the organic thin film transistor according to Example 1 shows charge mobility of about 0.31 cm2/Vs and a current on/off ratio of about 7.4×106, which indicate improved characteristics compared to a conventional thin film transistor.