Patent Application
20100006830
This application claims the benefit of priority under 35 U.S.C. §119 from Korean Patent Application No. 10-2008-0066457, filed on Jul. 9, 2008 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field
Example embodiments relate to a high-performance organic semiconductor compound based on a 2,7-bis-(vinyl)[1]benzothieno[3,2-b]benzothiophene backbone, an organic semiconductor thin film using the same, an organic thin film transistor using the organic semiconductor compound and methods of forming the same. Other example embodiments relate a symmetrically substituted high-performance organic semiconductor compound, which provides films with increased stability over a period of time if applied to various organic electronic components and has high field-effect mobilities (charge mobilities) and high on/off ratios (on/off current ratio), that may be efficiently applied to organic flexible electronic devices.
2. Description of the Related Art
Recently, attention has been given to conjugated organic materials used for organic semiconductors in various opto-electronic apparatuses. Research on conjugated organic materials has been performed for the past few decades, because conjugated organic materials may be used as a component for organic thin film transistors (OTFTs), organic light-emitting diodes (OLEDs), photovoltaic cell, sensors and radio frequency identification (RF-ID) tags. Much research has been conducted on organic thin film transistors because the preparation of organic thin film transistors using organic semiconductors is substantially simple and organic thin film transistors have a substantially high compatibility with plastic substrates for flexible displays compared to thin film transistors using amorphous silicon and polysilicon.
In particular, chalcogenophenes in fused aromatic ring systems (e.g., thiophene) and/or π-extended heteroarenes including selenophene have a similar structure to that of oligoacene. As such, research of such compounds is being actively conducted. The mobilities of the charge carriers in organic semiconductors outperform the mobility of amorphous silicon (0.5 cm2/Vs). For example, the mobility of 2,7diphenyl[1]benzothieno[3,2-b]benzothiophene (DPh-BTBT) is 2.0 cm2/Vs, the mobility of 2,7diphenyl[1]benzoselenopheno[3,2-b]benzobenzoselenophene (DPh-BSBS) is 0.3 cm2/Vs and the mobility of dinaphtho[2,3-b:2′,3′-f]chalcogenopheno[3,2-b]chalcogenophenes (DNTT and DNSS)˜2.9 is 1.0 cm2/Vs. These compounds are regarded as high-performance OTFT materials with reasonable stabilities if operated under various conditions.
Example embodiments relate to a high-performance organic semiconductor compound based on a 2,7-bis-(vinyl)[1]benzothieno[3,2-b]benzothiophene backbone, an organic semiconductor thin film using the same, an organic thin film transistor using the organic semiconductor compound and methods of forming the same.
Example embodiments include an organic semiconductor compound having increased film stability over a period of time, and substantially high field-effect mobilities and on/off ratios. Example embodiments include a highly-arranged organic semiconductor thin film using the organic semiconductor compound. Example embodiments include a high-performance organic thin film transistor (i.e., organic electronic device) using the organic semiconductor compound as an organic active layer.
Example embodiments include an organic semiconductor compound based on (or formed from) a 2,7-bis-(vinyl)[1]benzothieno[3,2-b]benzothiophene backbone (BTBT), and electronic characteristics of the organic semiconductor compound are evaluated. In particular, 2,7-bis-(2-cyclohexyl-vinyl)[1]benzo thieno[3,2 b]benzothiophene (DCV-BTBT) and 2,7-distyryl-[1]benzothieno[3,2-b]benzothiophene (DPV-BTBT) may be applied to an organic semiconductor device herein to explain non-limiting example embodiments.
Example embodiments include an organic semiconductor compound synthesized by forming a vinyl group from the reaction between a phosphonate derivative represented by Formula 1 and an aldehyde derivative represented by Formula 2 below.
In Formula 2, A may be at least one selected from the group consisting of a cyclic alkyl group, a phenyl group, a phenyl group substituted with a C1-C12 alkyl group, a thiophenyl group, a thiophenyl group substituted with a C1-C12 alkyl group, a naphthyl group, a naphthyl group substituted with a C1-C12 alkyl group, a biphenyl group, a biphenyl group substituted with a C1-C12 alkyl group, an anthracenyl group, an anthracenyl group substituted with a C1-C12 alkyl group, a phenanthrenyl group, a phenanthrenyl group substituted with a C1-C12 alkyl group, a fluorenyl group, a fluorenyl group substituted with a C1-C12 alkyl group, a pyridinyl group, a pyridinyl group substituted with a C1-C12 alkyl group, a pyrrolyl group, a pyrrolyl group substituted with a C1-C12 alkyl group, a furanyl group, a furanyl group substituted with a C1-C12 alkyl group and combinations thereof.
According to example embodiments, the vinyl group may be derived by mixing the phosphonate derivative with the aldehyde derivative. The aldehyde derivative may be at least one selected from the group consisting of benzaldehyde, alkylbenzaldehyde substituted with a C1-C12 alkyl group, thiophenylaldehyde, alkylthiopenealdehyde substituted with a C1-C12 alkyl group and mixtures thereof. The phosphonate derivative may be 2,7-dibromomethyl[1]benzothieno[3,2-b]benzothiophene. The vinyl group may be 2,7-bis-(vinyl)[1]benzothieno[3,2-b]benzothiophene.
Example embodiments include a method of preparing an organic semiconductor compound, the method including forming a vinyl group by reacting a phosphonate derivative represented by Formula 1 and an aldehyde derivative represented by Formula 2 above.
In Formula 2, A may also be a substituted or unsubstituted cyclic alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted thiophenyl group, a substituted or unsubstituted pyridinyl group, a substituted or unsubstituted pyrrolyl group or a substituted or unsubstituted furanyl group. According to the reaction, the BTBT backbone has a vinyl group in the trans configuration using Horner-Emmons coupling reactions between the phosphonate and aldehyde derivatives and any compound having this configuration may be used.
According to example embodiments, forming the vinyl group may include introducing the vinyl group into the BTBT backbone of the phosphonate derivative.
Example embodiments include an organic semiconductor compound represented by one of Formulae 3 to 9 below.
In Formula 4, n is in a range of about 0 to about 11.
In Formula 6, n is in a range of about 0 to about 11.
In Formula 8, m is in a range of about 1 to about 5, and n is in a range of about 0 to about 11.
Example embodiments include an organic semiconductor thin film prepared using the organic semiconductor compound and an electronic device including the organic semiconductor thin film as a carrier transport layer.
These and/or other aspects will become apparent and more readily appreciated from the following description of example embodiments, taken in conjunction with the accompanying drawings of which:
Various example embodiments will now be described more fully with reference to the accompanying drawings in which some example embodiments are shown. However, specific structural and functional details disclosed herein are merely representative for purposes of describing example embodiments. Thus, the invention may be embodied in many alternate forms and should not be construed as limited to only example embodiments set forth herein. Therefore, it should be understood that there is no intent to limit example embodiments to the particular forms disclosed, but on the contrary, example embodiments are to cover all modifications, equivalents, and alternatives falling within the scope of the invention.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises,” “comprising,” “includes” and/or “including,” if used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.
It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may in fact be executed substantially concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
In order to more specifically describe example embodiments, various aspects will be described in detail with reference to the attached drawings. However, the present invention is not limited to example embodiments described.
Example embodiments relate to a high-performance organic semiconductor compound based on a 2,7-bis-(vinyl)[1]benzothieno[3,2-b]benzothiophene backbone, an organic semiconductor thin film using the same, an organic thin film transistor using the organic semiconductor compound and methods of forming the same. Other example embodiments relate a symmetrically substituted high-performance organic semiconductor compound, which provides films with increased stability over a period of time if applied to various organic electronic components and has high field-effect mobilities (charge mobilities) and high on/off ratios (on/off current ratio), that may be efficiently applied to organic flexible electronic devices.
Example embodiments include an organic semiconductor compound synthesized with a vinyl group by reacting a phosphonate derivative represented by Formula 1 and an aldehyde derivative represented by Formula 2 below:
wherein A is at least one selected from the group consisting of a cyclic alkyl group, a phenyl group, a phenyl group substituted with a C1-C12 alkyl group, a thiophenyl group, a thiophenyl group substituted with a C1-C12 alkyl group, a naphthyl group, a naphthyl group substituted with a C1-C12 alkyl group, a biphenyl group, a biphenyl group substituted with a C1-C12 alkyl group, an anthracenyl group, an anthracenyl group substituted with a C1-C12 alkyl group, a phenanthrenyl group, a phenanthrenyl group substituted with a C1-C12 alkyl group, a fluorenyl group, a fluorenyl group substituted with a C1-C12 alkyl group, a pyridinyl group, a pyridinyl group substituted with a C1-C12 alkyl group, a pyrrolyl group, a pyrrolyl group substituted with a C1-C12 alkyl group, a furanyl group, a furanyl group substituted with a C1-C12 alkyl group and mixtures thereof.
Embodiments include an organic semiconductor compound represented by one of Formulae 3 to 9 below:
wherein n is in a range of about 0 to about 11,
wherein n is in a range of about 0 to about 11,
wherein m is in a range of about 1 to about 5, and n is in a range of about 0 to about 11,
Example embodiments include an organic semiconductor thin film prepared using the above organic semiconductor compound.
Example embodiments include an electronic device including the above organic semiconductor thin film as a carrier transport layer.
Example embodiments include a method of preparing an organic semiconductor compound, the method including forming a vinyl group by mixing (or reacting) a phosphonate derivative represented by Formula 1 and an aldehyde derivative represented by Formula 2 below:
wherein A is at least one selected from the group consisting of a substituted or unsubstituted cyclic alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted thiophenyl group, a substituted or unsubstituted pyridinyl group, a substituted or unsubstituted pyrrolyl group, a substituted or unsubstituted furanyl group and mixtures thereof.
Research has been conducted on π-conjugated heteroarene cores (BTBT) with a vinyl group, as an organic semiconductor. An organic semiconductor compound including the BTBT backbone is prepared according to the reaction scheme below.
The objective compound may be synthesized using Horner-Emmons coupling reactions between the phosphonate and aldehyde derivatives as shown in the reaction scheme above. It is known that Horner-Emmons coupling reactions form trans-structures (S. Pfeiffer, H. H. Horhold, Macromol. Chem. Phys., 1998, 200, 1870). Purified 2,7-bis-(2-cyclohexyl-vinyl)[1]benzo thieno[3,2-b]benzothiophene (DCV-BTBT) and 2,7-distyryl-[1]benzothieno[3,2-b]benzothiophene (DPV-BTBT) by sublimation may be identified using high-resolution mass spectrometry and elemental analysis. The aldehyde derivative of the reaction scheme shown above is a non-limiting example and may also be various compounds (e.g., arylaldehyde and arylaklylaldehyde). In particular, any aldehyde that is used to synthesize the organic semiconductor compound and attaches a vinyl group to the BTBT backbone may be used. In addition to the benzaldehyde, alkylbenzaldehyde substituted with an alkyl group (particularly, alkylbenzaldehyde substituted with a C1-C12 alkyl group, wherein a C1 alkyl group is methyl group having a single carbon atom), thiophenylaldehyde (thiopenealdehyde), and alkylthiopenealdehyde substituted with an alkyl group (particularly, alkylthiopenealdehyde substituted with a C1-C12 alkyl group) may also be used.
[1]benzothieno[3,2-b]benzothiophene 2,7-dicarboxylate is synthesized from 2,2′-diamino-(E)-stilbene-4,4′-dicarboxylate prepared using a method disclosed in P. Kaszynski, D. A. Dougherty, J. Orgs. Chem., 1993, 58, 5209. The synthesis process includes 10 steps or operations. A commercially available 4-(chloromethyl)benzoic acid is initially converted into ethyl ester and nitrated to prepare ethyl-4-(chloromethyl)-3-nitrobenzoate. Two ester molecules are then condensed and treated with sodium ethoxide to prepare diethyl 2,2′-dinitro-(E)-stilbene-4,4′-dicarboxylate. The nitro group is reduced using iron powder in ethanol in the presence of hydrochloric acid to prepare 2,2′-diamino-(E)-stilbene-4,4′-dicarboxylate. The amino group is converted into a xanthate group via a bisdiazonium salt. Stilbene bisxanthate is treated with bromine in acetic acid to prepare a fused thiopene ring. [1]benzothieno[3,2-b]benzothiophene 2,7-dicarboxylate is stirred in THF, and reduced using LiAlH4 to prepare 2,7-dihydromethyl[1]benzothieno[3,2-b]benzothiophene with a substantially high yield. As such, produced diol is treated with phosphorus tribromide in DMF at room temperature to prepare 2,7-dibromomethyl[1]benzothieno[3,2-b]benzothiophene. 2,7-diethylphosphorylmethyl[1]benzothieno[3,2-b]benzothiophene, as one of the precursors of Horner-Emmons olefination, is prepared by the reaction between dibromide and triethylphosphite. Organization of oligomers in a thin film may be realized by the introduction of a vinylene unit. As shown in the reaction scheme above, the semiconductor compound is synthesized by a Horner-Emmons coupling reaction between the phosphonate derivative and the aldehyde derivative. Purified DCV-BTBT and DPV-BTBT by sublimation are identified using high-resolution mass spectrometry and elemental analysis.
Referring to
Results of differential scanning calorimetry (DSC) represent melting properties of the two materials. In DCV-DTBT, single endothermic and exothermic transfers are respectively observed at 307° C. (79.9-J/g) and 257° C. in heating and cooling cycles. In DPV-BTBT, double endothermic peaks are observed at 325° C. (35.87-J/g) and 352° C. (58.63-J/g). In a cooling trace, a single peak is observed at 330° C. (47.84-J/g).
Referring to
In the PL spectra, the differences in the emission maximum between the solution and film states of DCV-BTBT and DPV-BTBT are respectively 47-nm and 60-nm, indicating the presence of extremely strong intermolecular interactions in the film states (J. H. Park, D. S. Chung, J. W. Park, T. Ahn, H. Kong, Y. K. Jung, J. Lee, M. H. Y, C. E. Park, S. K. Kwon, D. D. Shim, Org. Lett., 2007, 9, 2573). The UV-vis spectra of DCV-BTBT and DPV-BTBT showed long-wavelength absorption edges at 379-nm and 419-nm respectively, which corresponded to HOMO-LOMO energy gaps of 3.25-eV and 2.97-eV, respectively. Theses values are substantially higher than the energy gap of pentacene (2.2-eV) (I. G. Hill, J. Hwang, A. Kahn, C. Hung, J. E. McDermott, Appl. Phys. Lett., 2007, 90, 012109). The HOMO-LOMO energy gap decreases with an increase in the length of π-conjugation.
Referring to
Next, structural properties are measured using X-ray diffraction (XRD).
Referring to
As shown in
Thin films of the two conjugated oligomers are formed by vacuum evaporation onto either an untreated, or octadecyltrichlorosilane (OTS)-coated, Si/SiO2 substrate at various temperatures (Tsub=25° C., 50° C. and 80° C.). All the OTFTs showed typical p-channel TFT characteristics. The OTFTs of DCV-BTBT and DPV-BTBT are fabricated with gold (Au) electrodes using top-contact geometry. Gold source and drain contacts (50-nm) are deposited onto an organic layer using a shadow mask. The channel length (L) and width (W) are respectively 50-μm and 1000-μm.
From the electrical transfer characteristics, several parameters (e.g., the carrier mobility (μTFT), on/off current ratio (Ion/Ioff), threshold voltage (Vth) and subthreshold swing (S) for each device are estimated, as shown in Table 1 below. It is identified that a high carrier mobility may be obtained with DPV-BTBT even after the devices have been exposed to air for 2 months. The DPV-BTBT fabricated under various conditions shows μFET ranging from about 0.003-cm2/Vs to about 0.437-cm2/Vs and on/off ratios ranging from about 105 to about 107 under various conditions. In particular, increased FET characteristics with μFET higher than 0.437-cm2/Vs (measured in the saturation regime) and on/off ratios of greater than 105 are observed in DPV-BTBT devices fabricated on OTS-treated substrate at a Tsub of 80° C.
Referring to
Table 1 shows a set of field-effect mobility (μTFT), on/off current ratio (Ion/Ioff), threshold voltage (Vth), and subthreshold swing data of DPV-BTBT based top-contacting field-effect transistor, wherein DPV-BTBT is vacuum deposited on differently treated SiO2 surfaces at different substrate temperatures (Tsub), wherein the data are measured after the devices have been exposed to air for 2 months.
The TFT performance depends critically on the side-end group of the active materials. In general, the addition of the bulky substituents as cyclohexyl groups to the ends of the oligomer is expected to increase its solubility, enhancing the solution processing (J. Locklin, D. Li. S. C. B. Mannsfeld, E.-J. Borkent, H. Meng, R. Advincula. Z. Bao, Chem. Mat., 2005, 17, 3366). DCV-BTBT is not sufficiently soluble in any organic solvent. Moreover, optical microscopic observations revealed that films of cyclohexyl-substituted vinyl-BTBT did not have a continuous morphology, as shown in
Referring to
In summary, a series of substituted vinyl-BTBT molecules are synthesized by a rout involving the Horner-Emmons coupling reaction. The oligomers show high thermal stability. DPV-BTBT exhibits increased field-effect performance with a mobility as high as 0.46 and an on/off ratio of up to 1.2×107. It is notable that there is not significant change in the mobility of DPV-BTBT even after the device has been exposed to air for at least 60 days (further monitoring is in progress) showing that it is an air-stable p-channel organic semiconductor that may be applied to all organic flexible electronic devices.
1H and 13C NMR spectra are recorded in CDCl3 using an Advance 300 MHz Bruker spectrometer. 1H NMR chemical shifts in CDCl3 is measured relative to those in CHCl3 (7.27 ppm) and 13C NMR chemical shifts in CDCl3 is measured relative to those in CHCl3 (77.23 ppm).
TGA analyses are performed on a TGA Q50 TA instrument at 10° C. min−1 under a nitrogen atmosphere. DSC analyses are performed on an exothermic 2910 TA instrument at 10° C. min−1 under nitrogen flow. UV-vis absorption spectra are recorded on a Beckman coulter DU 800 spectrometer using quartz cells with path-length of 2.5-cm. For solid-state measurements, oligomers are thermally evaporated in a vacuum chamber on a quartz plate to form a film having a thickness of 300-Å at a deposition rate of 0.5-Å s−1. XRD analyses are performed at room temperature with a Mac Science (M18XHF-22) diffraction meter using CuKα radiation as the X-ray source at 50-kV and 100-mA. The data is collected in an existing θ-2θ configuration (2.5-30°) from thin films thermally evaporated on SiO2/Si substrates in a vacuum chamber to form a film having a thickness of 300-Å at a rate of 0.5-Å s−1. AFM images of the vacuum-deposited thin films are obtained using a PSIA XE-100 advanced scanning microscope. A voltammetric apparatus used is a CH instruments model 700C electrochemical workstation. Cyclic voltammograms (CVs) are obtained at room temperature in a three-electrode cell equipped with a working electrode (Au), a reference electrode (Ag/AgCl) and a counter electrode (Pt) in dichlorobenzene containing tetrabutylammonium hexafluorophosphate (Bu4N+PF6−, 0.1 M) as the supporting electrolyte at a scan rate of 100-mV/s. All the potentials are calibrated with the standard ferrocene/ferrocenium redox couple (E=+0.41 V measured).
Field-effect measurements are performed using top-contact FETs. TFT devices with a channel length (L) of 50-μm and a channel width (W) of 1000-μm are fabricated on a thermally oxidized highly n-doped silicon substrate. A SiO2 gate dielectric has a thickness of 300-nm. An organic semiconductor (300 A) is evaporated onto a non-pretreated, or octadecyltrichlorosilane (OTS)-pretreated, oxide surface (0.1 Å s−1 at 1×10−6 torr). Gold source/drain electrodes are evaporated on top of the films through a shadow mask. All the measurements are performed at room temperature using a 4155C Agilent semiconductor parameter analyzer and mobilities (μ) are calculated in the saturation regime by using the relationship μsat=(2IDSL)/(WC(VG−Vth)2), where IDS is a source-drain saturation current, C (1.18×10−8 F) is an oxide capacitance, VG is a gate voltage and Vth is a threshold voltage.
All chemicals are purchased from Aldrich and Lancaster.
LiAlH4 (0.74-g, 19.5-mmol) is added to a solution of [1]benzothieno[3,2-b]benzothiophene 2,7-dicarboxylate (1.50-g, 3.9-mmol) in THF (40-ml). The reaction mixture is stirred overnight. The insoluble material is removed by filtration and washed with hot dimethyl sulfoxide (DMSO). The filtrate and washings are collected, and the product is precipitated by adding 50-mL of 1 N HCl. The product is collected by filtration to obtain 1.86-g (75%) of pure 2,7-bis(dihydromethyl)[1]benzothieno[3,2-b]benzothiophene.
1H NMR (300 MHz, DMSO): δ 8.05 (s, 2H), 7.98 (d, 2H, J=8.1 Hz), 7.48 (d, 2H, J=8.2 Hz), ), 5.38 (t, 2H, J=5.6 Hz), 4.69 (d, 4H, J=5.3 Hz).
Phosphorustribromide (3.24-g, 11.9-mmol) is added dropwise to a suspension of 2,7-bis(dihydroxymethyl)[1]benzothieno[3,2-b]benzothiophene (0.9-g, 2.99-mmol) in DMF (20-ml) at 0° C. Upon the formation of a yellow precipitate, the mixture is warmed to room temperature and stirred for 4 hours. The solids are collected by filtration and washed with water and hexane to obtain 1.1-g (78%) of 2,6-bis(dibromomethyl)anthracene as a yellow solid. The product is further purified by recrystallization from DMF.
1H NMR (300 MHz, DMSO): δ 8.24 (s, 2H), 8.08 (d, 2H, J=8.2 Hz), 7.63 (d, 2H, J=8, 1 Hz), 4.91 (s, 4H).
2,6-bis(dibromomethyl)anthracene (1.1-g, 2.58-mmol) is added to triethylphosphite (30-ml), and the resulting solution is refluxed for 12 hours. The solvent is removed in vacuum, and the residue is purified by silica gel column chromatography using ethyl acetate/dichloromethane (2:1) as an eluent to obtain the produce (yield: 90%).
1H NMR (300 MHz, CDCl3): δ 7.87 (s, 2H), 7.84 (d, 2H, J=8.2 Hz), 7.42 (d, 2H, J=8.1 Hz), 4.05 (m, 8H), 3.36 (d, 4H, J=21.5 Hz), 1.27 (t, 12H, J=7.0 Hz). 13C NMR (75 MHz, CDCl3): (142.62, 142.58), 133.18, 131.90, (128.79, 128.67), (126.92, 126.84), (124.98, 124.88), 121.40, (62.33, 62.24), (34.81, 32.97), (16.45, 16.37).
LDA (1.5-M in cyclohexane, 4.0-ml, 6.0-mmol) is added dropwise to a stirred solution of 2,7-bis(diethylphosphorylmethyl)[1]benzothieno[3,2-b]benzothiophene (1.3-g, 2.41-mmol) in anhydrous THF (50-ml) at −78° C. under a nitrogen atmosphere. The mixture is stirred for 1 hour, and then cyclohexanecarbaldehyde (0.67-g, 6.02-mmol) in THF (10-ml) is added dropwise over a period of 10-minutes. After the mixture is stirred for 2-hours at −78° C. and for 12 hours at room temperature, 5-ml of water is added thereto, and the solvent is evaporated. The residue is washed with water and MeOH. The desired produce is separated by sublimation.
Calcd. for C30H32S2: 456.1945. Found: 456.1951.
Anal. Calcd. for CHS: C, 78.90; H, 7.06; S, 14.04. Found: C, 78.48; H, 7.14; S, 14.36.
LDA (1.5 M in cyclohexane, 4.0-ml, 6.0-mmol) is added dropwise to a stirred solution of 2,6-bis(diethylphosphorylmethyl)anthracene (1.3-g, 2.41-mmol) in anhydrous THF (50-ml) at −78° C. under a nitrogen atmosphere. The mixture is stirred for 1 hour, and then benzaldehyde (0.67-g, 6.0-mmol) in THF (20-ml) is added dropwise over a period of 10 minutes. After the mixture is stirred for 2 hours at −78° C., and for 12 hours at room temperature, 5-ml of water is added thereto, and the solvent is evaporated. The residue is washed with water and MeOH. The desired produce is separated by sublimation.
HRMS:
Calcd. for C30H20S2: 444.1006. Found: 444.1008.
Anal. Calcd. for CHS: C, 81.04; H, 4.53; S, 14.42. Found: C, 81.04; H, 4.55; S, 14.40.
Any other compound including the BTBT backbone and another substituent may be synthesized using a similar method. A vinyl group may be introduced into the BTBT backbone by the Horner-Emmons coupling reaction between the phosphonate derivative and the aldehyde derivative.
As described above, according to example embodiments, the organic semiconductor compound based on BTBT backbone with a vinyl group has increased stability over a period of time and increased electrical properties (e.g., field-effect mobilities and on/off ratios).
The foregoing is illustrative of example embodiments and is not to be construed as limiting thereof. Although a few example embodiments have been described, those skilled in the art will readily appreciate that many modifications are possible in example embodiments without materially departing from the novel teachings and advantages. Accordingly, all such modifications are intended to be included within the scope of this invention as defined in the claims. In the claims, means-plus-function clauses are intended to cover the structures described herein as performing the recited function, and not only structural equivalents but also equivalent structures. Therefore, it is to be understood that the foregoing is illustrative of various example embodiments and is not to be construed as limited to the specific embodiments disclosed, and that modifications to the disclosed embodiments, as well as other embodiments, are intended to be included within the scope of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2008-0066457 | Jul 2008 | KR | national |
