SILYLATED BENZOTHIENO[3,2-B][1 ]BENZOTHIOPHENE

DERIVATIVES, METHOD FOR MANUFACTURING THEM AND

ELECTRONIC DEVICES COMPRISING THEM

TECHNICAL FIELD

The invention relates to new organosilicon monofunctional di-substituted derivatives of ben- zothienobithiophene . The invention also relates to a method for manufacturing these compounds, semiconduc- tor layers and electronic devices comprising these compounds and use of these compounds.

BACKGROUND

Organic electronics have nowadays become one of the fast growing fields of science and technology based on the semiconducting properties of n-conjugated oligomers and polymers. Application of organic semi- conductors as thin active layers allows to fabricate flexible transparent large-area electronic devices. One of the basic elements of many of them is an organ- ic field-effect transistor (OFET) . It was established that the charge transport in OFETs takes place primar- ily in a few nanometers thick layer of the organic semiconductor near to the semiconductor-isolator in- terface .

SUMMARY

An example embodiment of a compound of gen- eral formula (I) is characterized by what is presented in claim 1.

An example embodiment of a method for manu- facturing a compound of general formula (I) is charac- terized by what is presented in claim 8.

An example embodiment of a semiconductor lay- er is characterized by what is presented in claim 9. An example embodiment of an electronic device is characterized by what is presented in claim 14.

An example embodiment of a method for manu- facturing the electronic device is characterized by what is presented in claim 18.

An example embodiment of the use of the com- pound of general formula (I) is characterized by what is presented in claim 21. BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and constitute a part of this specification, illus- trate embodiments of the invention and together with the description help to explain the principles of the invention. In the drawings:

Fig. 1 is a schematic representation of a monolayer formed by the compound (la) .

Fig. 2 is a schematic representation of a monolayer formed by the compound (lb) .

Fig. 3 is a schematic representation of a monolayer field-effect transistor.

Fig. 4 is an AFM scan of the monolayer film of the compound (Ia-1) .

Fig. 5 is a profile of the monolayer film of the compound (Ia-1) .

Fig. 6 is an AFM scan of the monolayer film of the compound (Ib-1) .

Fig. 7 is a profile of the monolayer film of the compound (Ib-1) .

Fig. 8 is a transfer curve of OFET based on the monolayer of the compound (Ia-1) .

Fig. 9 is a transfer curve of OFET based on the monolayer of the compound (Ib-1) .

DETAILED DESCRIPTION According to an example embodiment there is provided a new compound of general formula (I)

wherein

R ¹ is C ₂ -C ₁₃ -alkyl,

R is C ₃ -C ₁₈ -alkenyl ,

X is 0 or halogen, and

y is 1 or 2,

provided that when y is 1, X is halogen and when y is 2, X is 0.

Compounds of general formula (I) are organo- silicon monofunctional di-substituted derivatives of [1] benzothieno [3, 2-b] [1] -benzothiophene (BTBT) . Sub- stituent R ¹ may be a linear or branched C ₂ -C ₁₃ alkyl group. Substituent R may be a linear or branched C ₃ -C ₁₈ -alkenyl group. The alkenyl and alkyl group may be un- substituted or substituted. Symbol X is an oxygen atom or a halogen atom CI, Br or I.

In one embodiment the compound has formula (I) and R is linear C ₃ -C ₁₂ -alkenyl.

In one embodiment, where y is 1 and X is hal- ogen (Hal) the compound has the following formula (la)

wherein

R ¹ is C ₂ -C ₁₃ -alkyl, and

R is C ₃ -C ₁₈ -alkenyl.

In one embodiment the compound has formula (la) and R is C ₃ -C ₁₂ -alkenyl

In one embodiment the compound has formula (la) and X is CI. In one embodiment, where y is 2 and X is oxy- gen the compound has the following formula (lb)

wherein

R ¹ is C ₂ -C ₁₃ -alkyl, and

R is C ₃ -C ₁₈ -alkenyl.

In one embodiment the compound has formula (lb) and R is C ₃ -C ₁₂ -alkenyl.

In one embodiment the compound has formula (la) wherein R ¹ is C ₆ -alkyl, R is C ₁₀ -alkenyl and X is CI.

In one embodiment the compound has formula (lb) wherein R ¹ is C ₆ -alkyl and R is Cn -alkenyl.

The compound (I) may form layers on surfaces of a substrate. The functional group of the compound has an affinity to the appropriate substrate. It may anchor the compound to it. The functional group in compound (la) is halogensilyl (X = Hal) . The function- al group in compound (lb) is disiloxane (X = 0) .

The alkyl groups R ¹ of compound (I) improves the solubility in common organic solvents, like hex- ane, toluene, benzene, THF, chloroform, chlorobenzene and similar, as well as in their mixtures.

The compound (I) having disiloxane functional group is chemically stable. It has good air and ther- mal stability. This compound (I) is stable under ambi- ent atmosphere up to 300°C.

According to an example embodiment there is provided a new method for manufacturing a di- substituted compound of formula (I) . A method for man- ufacturing a compound of general formula (I)

wherein

R is C ₀ -C ₁₃ -alkyl,

R is C ₃ -C ₁₈ -alkenyl,

X is 0 or halogen

y is 1 or 2,

provided that when y is 1, X is halogen and when y is 2, X is 0

comprises :

a) preparation of 2-alkyl- [ 1 ] benzothieno [ 3 , 2- b] [ 1 ] benzothiophene (3)

n =2-13 by acylation of [ 1 ] benzothieno [3,2- b] [ 1 ] benzothiophene and by reduction the obtained [ 1 ] benzothieno [ 3 , 2- b] [ 1 ] benzothio-2-yl-alkan-l-one (2)

m=l-12

b) preparation of 2-alkyl-7-alken-l- yl [ 1 ] benzothieno [ 3 , 2-b] [ 1 ] benzothiophene, . ( 8 )

p=l-9

n=0-13

by acylation of 2-alkyl- [ 1 ] benzothieno [ 3 , 2- b] [ 1 ] benzothiophene (3) or [ 1 ] benzothieno [ 3 , 2- b] [ 1 ] benzothiophene (1) with a dihalogen-alkanoyl chloride (5)

CI (CO) (CH ₂ ) _p CH (Hal) CH ₂ (Hal) and by reduction the obtained compound (6)

n=0-13 to form the compound (7)

and by subsequent elimination of halogen atoms from the compound (7) to form a double bond and the compound (8), and

preparation of a compound of formula (I) wherein y is 1 and X is halogen, i.e. a compound of formula (la)

by hydrosilylation of 2-alkyl-7-alken-l- yl [ 1 ] benzothieno [3, 2-b] [ 1 ] benzothiophene (8) with dimethylhalogensilane of formula H (CH ₃ ) ₂ Si-Hal, or d) preparation of a compound of formula (I) wherein y is 2 and X is 0, i.e. a compound of formula (lb)

by hydrosilylation of 2-alkyl-7-alken-l- yl [1] benzothieno [3, 2-b] [1] benzothiophene (8) with tetramethyldisiloxane to form a compound (9)

and further by reacting the compound (9) with the compound (8) under hydrosilylation conditions.

In one embodiment the method comprises manu- facturing a di-substituted compound of general formula (I), wherein R ¹ is C ₂ -C ₁₃ -alkyl, R is C ₃ -C ₁₈ -alkenyl, X is 0 or halogen and y is 1 or 2, provided that when y is 1, X is halogen and when y is 2, X is 0.

The method for manufacturing the di- substituted compound of formula (la) comprises steps a) to c) . A method for manufacturing a compound of formula (la)

wherein

R ¹ is C ₀ -C ₁₃ -alkyl,

R is C ₃ -C ₁₈ -alkenyl,

Hal is halogen, comprises:

a) preparation of 2-alkyl- [ 1 ] benzothieno [ 3 , 2- b] [ 1 ] benzothiophene (3)

by acylation [ 1 ] benzothieno [3,2- b] [ 1 ] benzothiophene and by reduction the obtained [ 1 ] benzothieno [ 3 , 2- b] [ 1 ] benzothio-2-yl-alkan-l-one (2)

b) preparation of 2-alkyl-7-alken- yl [1] benzothieno [3, 2-b] [ 1 ] benzothiophene (8)

by acylation of 2-alkyl- [ 1 ] benzothieno [ 3 , 2^- b] [ 1 ] benzothiophene (3) or [1] benzothieno [3, 2- b] [ 1 ] benzothiophene (1) with a dihalogen-alkanoyl chloride (5)

and by reduction the obtained compound (6)

to form the compound (7)

and by subsequent elimination of halogen atoms from the compound (7) to form a double bond and the compound (8), and

c) preparation of a compound of formula (la)

by hydrosilylation of 2-alkyl-7-alken-l- yl [ 1 ] benzothieno [ 3 , 2-b] [ 1 ] benzothiophene (8) with di- methylhalogensilane of formula H (CH ₃ ) ₂ Si-Hal .

In one embodiment the method comprises manu- facturing a compound of formula (la), wherein R ¹ is C ₂ - C ₁₃ -alkyl, R is C ₃ -C ₁₈ -alkenyl and Hal is halogen.

The method for manufacturing the di- substituted compound of formula (lb) comprises steps a) , b) and d) . A method for manufacturing a compound of formula (la)

wherein R ¹ is C ₀ -C ₁₃ -alkyl,

R is C ₃ -C ₁₈ -alkenyl,

comprises:

a) preparation of 2-alkyl- [ 1 ] benzothieno [3 , 2- Jb] [ 1 ] benzothiophene (3)

by acylation of [ 1 ] benzothieno [ 3 , 2 jb] [ 1 ] benzothiophene (1)

and by reduction the obtained [ 1 ] benzothieno [3 , 2- i>] [ 1 ] benzothio-2-yl-alkan-l-one (2)

b) preparation of 2-alkyl-7-alken-l- yl [ 1 ] benzothieno [3, 2-b] [ 1 ] benzothiophene (8)

by acylation of 2-alkyl- [ 1 ] benzothieno [ 3 , 2- b] [ 1 ] benzothiophene (3) or [ 1 ] benzothieno [ 3 , 2- b] [ 1 ] benzothiophene (1) with a dihalogen-alkanoyl chloride (5)

CI (CO) (CH ₂ ) _P CH (Hal) CH ₂ (Hal) and by reduction the obtained compound

to form the compound (7)

and by subsequent elimination of halogen atoms from the compound (7) to form a double bond and the compound (8) , and

d) preparation of a compound of formula (lb)

by hydrosilylation of 2-alkyl-7-alken-l- yl [ 1 ] benzothieno [3 , 2-b] [ 1 ] benzothiophene (8) with tetramethyldisiloxane to form a compound (9)

and further by reacting the compound (9) with the compound (8) under hydrosilylation conditions.

In one embodiment the method comprises manu- facturing a compound of formula (lb), wherein R ¹ is C ₂ - C ₁₃ -alkyl and R is C ₃ -C ₁₈ -alkenyl. The acylation of step a) may be carried out by Friedel-Crafts acylation reaction. The acylation may be accomplished using different alkanoyl chlorides under Lewis acid catalyst such as anhydrous alumini- um(III) chloride catalysis. ·

The reduction of the ketone of formula (2) may be carried out by metal hydride reagents in appro- priate solvent. In one embodiment the reduction is carried out by sodium borohydride and anhydrous alu- minium (III) chloride in THF.

The acylation of step b) may be carried by using a dihalogen-alkanoyl chloride (5)

CI (CO) (CH ₂ ) _P CH(Hal)CH ₂ (Hal) , p is 1 - 9. The compound (5) is prepared from the corresponding alkanoyl chlo- ride of formula (4) CI (CO) (CH ₂ ) _P CH=CH ₂ having terminal double bond. The double bond of compound (4) is pro- tected by halogenation with halogen. The protected compound (5) may be reacted with the compound (1) or its' alkyl derivative (3) under Friedel-Crafts condi- tions to form unsymmetrical compound (6) with protect- ed terminal double bond. The compound (6) wherein n is 2-13 is formed when the compound (5) is reacted with the compound (3) . Reaction of the compound (5) with the compound (1) forms the compound (6) wherein n is 0. The usage of the compound (5) does not influence on the course and regioselectivity of the acylation reac- tion and lead to ketone (6) .

In one embodiment the acylation of step b) is carried out by di-brominated alkanoyl chloride (5) CI (CO) (CH ₂ ) _P CH (Br) CH ₂ (Br) , p is 1 - 9, under the pres- ence of Lewis acid.

The reduction of step b) may be carried out under the same conditions as the reduction of the ke- tone (2) in step a) to yield the compound (7) . In one embodiment the reduction is carried out by sodium bo- rohydride and anhydrous aluminium ( III ) chloride in THF. The double bond end-capped compound (8) may be prepared by elimination of halogen atoms from the compound (7), i.e. by deprotection of the double bond. In one embodiment the compound (7) may be reacted with Zn powder in acetic acid under heating to form the al- kyl-alkenyl end-capped compound (8). The deprotection of the double bond may be made with an excellent yield .

In step b) the usage of the compound (1) in reaction with the compound (5) forms compounds (6), (7) and (8) wherein n is 0 and the usage of the com- pound (1) in reaction with the compound (5) forms com- pounds (6), (7) and (8) wherein n is 2-13.

The compound (la) with chlorosilane function- al group may be prepared by hydrosilylation of com- pound (8) with dimethylchlorosilane .

The hydrosilylation of the compound (8) may lead to unsymmetrical compound (9) with hydridesilyl functional groups if the hydrosilylation is carried out with the excess of tetramethyldisiloxane (TMDS) . The compound (lb) with disiloxane functional group may be prepared by further reacting compound (9) under hy- drosilylation with compound (8).

In one embodiment the compound (lb) is pre- pared directly by hydrosilylation of compound (8) with half-molar amount of TMDS.

In the context of the method, the compound of general formula (I) may be any compound described in this specification.

The compound (I) can form layers or a mono- layer on surfaces of a substrate. The functional group of the compound (I) has an affinity to the appropriate substrate. The appropriate substrate may contain a hy- droxyl-containing surface, a hydrophilic surface or a hydrophilic surface.

Self-assembled monolayers (SAM) of organic molecules are molecular assemblies formed spontaneous- ly on surfaces by adsorption or by self-organization on the water-air interface in the Langmuir bath fol- lowed by transfer by the SAM to the substrate, i.e. by Langmuir-Blodgett or Langmuir-Schaffer methods.

Monofunctional compound (la) with chlorosilane functional group can form a monolayer on any hydroxyl-containing surfaces. Such monolayers may be produced by classical self-assembly from solution or by Langmuir-Blodgett transfer of the self-assembled Langmuir layer from the air-water interface.

Monofunctional compound (lb) with disiloxane functional group may form a monolayer on any hydro- philic surface. Such monolayers can be produced by Langmuir-Blodgett or Langmuir-Schafer transfer of the self-assembled monolayer from the air-water interface, due to weak Van-der-Waals interactions between the po- lar disiloxane groups of the compound (lb) and water surface .

The layers of compound of general formula (I) may have a mobility for charge carriers up to 1 cm ² /Vs. Charge carriers are e.g. positive hole charg- es .

Compound (I) may be used as a semiconductor layer. In one embodiment a semiconductor layer com- prises a compound of general formula (I)

wherein

R ¹ is C ₂ -C ₁₃ -alkyl,

R is C ₃ -C ₁₈ -alkenyl,

X is O or halogen,

y is 1 or 2, provided that when y is 1, X is halogen and when y is 2, X is 0.

In one embodiment the semiconductor layer comprises a monomolecular layer of the compound of general formula (I) .

In one embodiment the semiconductor layer comprises a self-assembled monolayer (SAM) of the com- pound of general formula (I) .

In one embodiment the semiconductor layer comprises a monomolecular layer formed from the com- pound of formula (la)

wherein R and R ¹ are as defined above.

In one embodiment the semiconductor layer comprises a monomolecular layer of the compound of formula (lb)

wherein R and R ¹ are as defined above. In the context of the semiconductor layer, the compound of general formula (I) may be any com- pound described in this specification.

In one example embodiment an electronic de- vice comprises the semiconductor layer as defined above.

The electronic device may be a field effect transistor or a sensor. The semiconductor layer may also be a layer in an organic light emitting diode.

In one embodiment the electronic device is a field effect transistor.

In one embodiment the field effect transistor is an organic field effect transistor comprising a substrate as a gate electrode, an insulator layer ap- plied to the substrate, a semiconductor layer which is applied to the insulator layer and comprises the com- pound of the general formula (I), and electrodes (drain and source) applied to the semiconductor layer.

In one embodiment the electronic device com- prises semiconductor layer comprising a monomolecular layer of formula (la)

wherein R and R ¹ are as defined above and the device is a monolayer organic field effect tran sistor .

In one embodiment the electronic device com prises semiconductor layer comprising a monomolecula layer of the compound of fo :mula (lb)

wherein R and R ¹ are as defined above and the device is a monolayer organic field effect tran- sistor .

In the context of the electronic device, the compound of general formula (I) may be any compound described in this specification.

According to an example embodiment there is provided a method for manufacturing an electronic de- vice, the method comprising

i) provision of a substrate,

ii) producing on the substrate a layer com- prising compound of the general formula (I)

wherein

R ¹ is C ₂ -C ₁₃ -alkyl,

R is C ₃ -C ₁₈ -alkenyl,

X is 0 or halogen,

y is 1 or ^' 2,

provided that when y is 1, X is halogen and when y is 2, X is O .

In one embodiment wherein the layer comprises a compound of formula (la) the layer is produced by self-assembly from solution or by Langmuir-Blodgett transfer of the self-assembled monolayer from the air- water interface.

In one embodiment wherein the layer comprises compound of formula (lb) the layer is produced by Langmuir-Blodgett or by Langmuir-Schafer transfer of the self-assembled monolayer from the air-water inter- face. In some embodiments, this provides a chemically stable compound (lb). A chemically stable compound (lb) is easy to process for solution processable elec- tronics .

In one embodiment wherein the layer comprises compound of formula (lb) the layer is produced by Langmuir-Blodgett technique.

In one embodiment the produced electronic de- vice is a monolayer organic field effect transistor.

In some embodiments, the self-assembly tech- niques provide fast and easy processable techniques in manufacturing the electronic device and/or the semi- conducting layer comprising the compound of formula (I) . Further, in some embodiments, the method for man- ufacturing an electronic device using these self- assembly techniques do not require any special prepa- ration conditions.

These methods have industrial modifications as a roll-on technology.

In some embodiments, produced monolayer OFETs are thermally and air stable and have good charge car- rier mobilities.

According to an example embodiment there is provided a use of a compound of general formula (I)

wherein

R ¹ is C ₂ -C ₁₃ -alkyl,

R isC ₃ -C ₁₈ -alkenyl,

X is 0 or halogen

y is 1 or 2,

provided that when y is 1, X is halogen and when y is 2, X is 0,

in a semiconducting layer in an electronic component.

The embodiments of the invention described hereinbefore may be used in any combination with each other. Several of the embodiments may be combined to- gether to form a further embodiment of the invention. A method, a composition or a use, to which the inven- tion is related, may comprise at least one of the em- bodiments of the invention described hereinbefore.

Reference will now be made to embodiments of the present invention, examples of which are illus- trated in the accompanying drawing. The description below discloses some embodiments of the invention in such a detail that a person skilled in the art is able to utilize the invention based on the disclosure. Not all steps of the embodiments are discussed in de- tail, as many of the steps will be obvious for the person skilled in the art based on this specification.

Figure 1 illustrates a monolayer formed by the compound (la) having a chlorosilane functional group. The compound (la) can form a monolayer on any hydroxyl-containing surfaces as shown on Fig. 1. Such monolayers can be produced either by classical self- assembly from solution or by Langmuir-Blodgett trans- fer of the self-assembled monolayer from the air-water interface .

Figure 2 illustrates a monolayer formed by the compound (lb) having a disiloxolane functional group. The compound (lb) can form a monolayer on any hydrophilic surface as shown on Fig. 2. The compound (lb) is chemically stable. This enables easy manufac- turing of a monolayer and processing for solution pro- cessable electronics. Such monolayers can be produced by Langmuir-Blodgett transfer of the self-assembled monolayer from the air-water interface. The SAM for- mation is due hydrogen bonds between the polar dis- iloxane groups of the compound (lb) and water mole- cules. The Langmuir-Blodgett technique is a fast and easy processable technique in manufacturing the elec- tronic device and the semiconducting layer. This meth- od using compound of formula (lb) does not require any special preparation conditions.

Monolayers can also be produced by Langmuir- Schafer transfer of the self-assembled monolayer from the air-water interface.

Figure 3 illustrates a structure of a field- effect transistor based on monolayer of the compound (la). Heavily doped silicon with thermally grown oxide was used for gate electrode (METAL) and gate dielec- trie (INSULATOR) correspondingly. Gold source and drain electrodes were evaporated on top of gate die- lectric using a shadow mask. The monolayer of the com- pound (la) between gold electrodes forms semiconduct- ing layer of the transistor (SEMICONDUCTOR) , allowing current flow from source to drain. By varying gate voltage source-drain current can be modulated several orders of magnitude.

Compound (lb) may also be used to form the monolayer of the OFET .

The material for the substrate as a gate electrode may be a heavily doped silicon wafer, alu- minium or other metal foil. The material for insulator layer applied to the substrate may be a silicon diox- ide, polymer, for example polystyrene, PMMA, and poly (p-xylylene) or aluminium oxide. The semiconductor layer which is applied to the insulator layer compris- es the compound of the general formula (I).

Other suitable substrate materials are die- lectrics, like glass or polymers such as PET, PEN, polyethersulfones , polyimides. Gates as well as source and drain electrodes can be either evaporated metals patterned via masks, or using lithography, or printed metals using conducting inks. Also it is possible to print organic conductors such as PEDOT, PANI and car- bon nanotubes and use them as electrodes.

Produced monolayer OFET is thermally and air stable and have good charge carrier mobilities.

EXAMPLE 1 - Synthesis of compounds IVa-1 and IVb-1

Reaction scheme

Aluminum chloride, ji™hexanoyl chloride, sodi- um borohydride, bromine, Zn powder, 1,1,3,3- tetramethyldisi loxane, dimethylchlorosilane were ob- tained from Sigma-AIdrich Co. and used without further purification. THF was dried over Ca¾ and distilled from LiAlHij. Dichloromethane was dried by distillation from PzO'i- Toluene and hexane were distilled before use. The solvents were evaporated in vacuum under a pressure of up to 1 torr at 40 °C. All reactions were carried out in inert atmosphere. [ 1 ] Benzothleno [ 3 , 2- b] [ 1 ] benzothiophene (BTBT) was prepared according to the technique described earlier [Kosata. B,, Kozmic V., Svoboda J, , Novotna V,, Vanek P., Giogarova M , Liquid Crystals, 2003, V. 30, 603-610] .

Analytical methods used

GPC analysis was performed by means of a Shi- madzu LClOA ^VP series chromatograph (Japan) equipped with an RID-10A ^vp refTactometer and 3PD-M1GA ^VP diode ma- trix as detectors and a Phenomenex column {USA} with a size of 7.8x300 mm ² filled with the Phenogel sorbent with a pour size of 500 A; THP was used as the eluent. For column chromatography, silica gel 60 ("Merck") was used. 1H NMR spectra were recorded at a "Bruker WP-

250 SY" spectrometer, working at a frequency of 250.13 MHz and utilising the DMSO-d ₆ signal (2.45 ppm) as the internal standard. ¹³ C and ²⁹ Si NMR spectra were recorded using a "Bruker Avance II 300" spectrometer at 75 MHz and 60 MHz, respectively. In the case of ¹ H NMR spectroscopy, the compounds to be analysed were taken in the form of 1% solutions in CDCI ₃ . In the case of ¹³ C and ²⁹ Si NMR spectroscopy, the compounds to be analysed were taken in the form of 5% solutions in CDCI ₃ . The spectra were then processed on the computer using the ACD Labs software.

Elemental analysis of C, H elements was car- ried out using CHN automatic analyzer CE1106 (Italy). Experimental error is 0.30-0.50%. Analysis of Br ele- ment was carried by visual titration technique using Hg(N0 ₃ ) ₂ and diphenylcarbazone as indicator. The burn ^¬ ing was done in the Sheninger flask using alkaline so- lution of hydrogen peroxide as an absorbent. Experi- mental error is 0.30-0.50%. Spectrophotometry tech- nique was used for the Si analysis.

[1] benzothieno [3 , 2-b] [1] benzothien-2-yl) -hexan-l-one (2-1)

A solution of [ 1 ] Benzothieno [ 3 , 2- b] [1] benzothiophene 1-1 (BTBT, 1.0 g, 4.2 mmol) in dry dichloromethane (160 ml) was cooled to -5°C and alumi ^¬ num chloride (1.0 g, 7.5 mmol) was added in one por- tion. The mixture was stirred for 1 h at the given temperature. Thereafter, n-hexanoyl chloride (1.0 g, 7.5 mmol) was added dropwise. After stirring during 1 h at -5 °C, the reaction mixture was poured into 200 ml water and 300 ml dichloromethane. The organic layer was washed with water and dried over sodium sulfate. The solvent was evaporated in vacuum and the product was purified by a column chromatography on silica gel (eluent toluene) to give pure compound 2-1(1.214 g, 86 %) .

¹ H NMR (250 MHz , CDC1 ₃ ) δ 8.55 (dd, J = 1.5, 0.6 Hz, 1H) , 8.06 (dd, J = 8.5, 1.5 Hz, 1H) , 7.94 (m, 3H) , 7.48 (m, 2H) , 3.07 (t, J = 7.3 Hz, 2H) , 1.81 (m, 2H) , 1.42 (m, 4H) , 0.94 (t, J = 7.0 Hz, 3 H) .

1 ³ C NMR (75 MHz, CDC1 ₃ ) <5 199.47, 142.78,

142.20, 136.88, 136.18, 133.60, 132.93, 132.72, 125.78, 125.08, 124.64, 124.45, 124.10, 122.01, 121.30, 38.73, 31.58, 24.19, 22.55, 13.96.

Anal, calcd. for C ₂₀ H ₁₈ OS ₂ : C, 70.97; H, 5.36; S, 18.95. Found: C, 71.08; H, 5.60; S, 18.63.

2-Hexyl- [1] benzothieno [3 , 2-b] [l]benzothiophene (3-1)

To a stirred solution of compound 2-1 (0.60 g, 1.8 mmol) in dry THF (30 ml) sodium borohydride (0.34 g, 8.9 mmol) and aluminum chloride (0.59 g, 4.4 mmol) were added successively. After the exothermic reaction had subsided, the mixture was stirred under reflux for 4 h. Thereafter, 10 ml of water were added dropwise. Then the reaction mixture was added to 100 ml of water and 150 ml of dichloromethane . The organic layer was washed with water and dried over sodium sul- fate. The solvent was evaporated in vacuum and the product was purified by a column chromatography on silica gel (eluent toluene) to give pure compound 3-1 (0.44 g, 77 %) .

¹ H NMR (250 MHz, CDC1 ₃ ) δ 7.90 (dd, J = 14.1, 7.5 Hz, 2H) , 7.80 (d, J = 8.2, 1H) , 7.73 (s, 1H) , 7.44 (m, 2H) , 7.30 (dd, J = 8.1, 1.3, 1H) , 2.78 (t, J = 7.5 Hz, 2H) , 1.72 (m, 2H) , 1.36 (m, 6H) , 0.92 (t , J = 6.9 Hz, 3 H) .

¹³ C NMR (75 MHz, CDC1 ₃ ) δ 199.57, 142.07, 1-40.07, 133.88, 133.26, 132.57, 131.01, 125.88, 124.78, 124.68, 123.97, 123.33, 121.38, 121.23, 36.12, 31.72, 31.64, 28.97, 22.60, 14.09.

Anal, calcd. for C ₂₀ H ₂₀ S ₂ : C, 74.03; H, 6.21; S, 19.76. Found: C, 74.18; H, 6.44; S, 19.88.

10,11-Dibromoundecanoyl chloride (5-1)

Br ₂ (16.00 g, 98.7 mmol) was slowly added to a solution of 10-Undecenoyl chloride 4-1 (20.00 g, 98.7 mmol) in of dry dichloromethane (50 ml) at 0°C . The mixture was stirred during 1 h at 0 °C and after that during additional 1 h at room temperature. After the evaporation of the solvent, the product was puri- fied by vacuum distillation (1 mbar, 170 °C) to give pure compound 5-1 (28.62 g, 80%) as a colorless liq- uid.

¹ n NMR (250 MHz, CDC1 ₃ ) δ 4.17 (m, 1H) , 3.86 (dd, J = 10.1, 4.3 Hz, 1H) , 3.63 (t, J = 10.1 Hz, 1H) , 2.90 (t, J= 7.3 Hz, 2H) , 2.15 (m, 1H) , 1.29-1.88 (overlapping peaks, 13H) .

1 ³ C NMR (75 MHz, CDC1 ₃ ) δ 173.76, 52.99,

47.04, 36.27, 35.93, 29.00, 28.88, 28.60, 28.31, 26.62, 24.98.

Anal. calcd. for CnH ₁₉ Br ₂ C10: C, 36.44; H, 5.28; Br, 44.08, CI, 9.78. Found: C, 36.70; H, 5.43; Br, 44.00; CI, 9.68.

10 , 11-dibromo-l- (7-hexyl [l]benzothieno [3,2- b] [l]benzothien-2-yl)undecan-l-one (6-1)

A solution of compound 3-1 (1.0 g, 3.1 mmol) in dry dichloromethane (60 ml) was cooled to -10°C and aluminum chloride (1.23 g, 9.2 mmol) was added in one portion. The mixture was stirred for 1 h at the given temperature. Thereafter, the reaction mixture was cooled to -70°C and compound 5-1 (5.0 g, 13.9 mmol) was added dropwise. After stirring during 2 h at -70 °C, the reaction mixture was added to 200 ml of water and 300 ml of dichloromethane. The organic layer was washed with water and dried over sodium sulfate. The solvent was evaporated in vacuum and the product was purified by a column chromatography on silica gel (el- uent toluene) to give pure compound 6-1 (1.62 g, 81 %) .

¹ H NMR (250 MHz, CDC1 ₃ ) δ 8.53

(d, J = 0.9 Hz, 1H) , 8.05 (dd, J = 8.4, 1.5 Hz, 1H) , 7.88 (d, J = 8.4 Hz, 1H) , 7.83 (d, J = 8.1 Hz, 1H) , 7.74 (s, 1H) , 7.31 (dd, J = 8.2, J ₂ = 1.3 Hz, 1H) , 4.18 (m, 1H) , 3.86 (dd, J = 10.3, 4.5 Hz, 1H) , 3.64 (t, J = 10.0 Hz, 1H) , 3.06 (t, J = 7.5 Hz, 2H) , 2.78 (t, J = 7.5 Hz, 2H), 2.14 (m, 1H) , 1.52-1.87 (overlap- ping peaks, 7H) , 1.26-1.51 (overlapping peaks, 14H) , 0.91 (t, J = 7.0 Hz, 3H) .

1 ³ C NMR (75 MHz, CDC1 ₃ ) δ 199.48, 143.16,

142.03, 141.37, 136.97, 136.44, 133.34, 132.14, 130.67, 126.17, 124.65, 124.49, 123.41, 121.71, 121.13, 53.11, 38.72, 36.35, 36.16, 36.00, 31.70, 31.57, 29.33, 29.31, 29.21, 28.96, 28.73, 26.71, 24.47, 22.59, 14.08.

Anal, calcd. for C ₃₁ H ₃₈ Br ₂ OS2 : C, 57.23; H, 5.89; Br, 24.56; S, 9.86. Found: C, 56.92; H, 5.65; Br, 24.76; S, 9.64. 2- (10 , 11-dibromoundecyl) -7-hexyl [1] benzothieno [3,2- b] [1] benzothiophene (7-1)

To a stirred solution of compound 6-1 (0.3 g, 0.5 mmol) in dry THF (40 ml), sodium borohydride (0.09 g, 2.3 mmol) and aluminum chloride (0.16 g, 1.2 mmol) were added successively. After the exothermic reaction had subsided, the mixture ^" was stirred under reflux for 4 h. Thereafter, 10 ml of water were added dropwise. Then the reaction mixture was added to 100 ml of water and 150 ml of dichloromethane . The organic layer was washed with water and dried over sodium sulfate. The solvent was evaporated in vacuum and the product was purified by a column chromatography on silica gel (el- uent toluene) to give pure compound 7-1 (0.22 g, 75 %) ·

¹ H NMR (250 MHz , CDC1 ₃ ) δ 7.78 (d, J = 8.1 Hz, 2H, ) , 7.72 (s, 2H) , 7.28 (dd, J = 8.2, J ₂ = 1.3 Hz, 2H) , 4.17 (m, 1H) , 3.86 (dd, J = 10.3, 4.4 Hz, 1H) , 3.63 (t, J = 10.0 Hz, 1H) , 2.77(t, J = 7.5 Hz, 4H) , 2.14 (m, 1H) , 1.52-1.87 (overlapping peaks, 7H) , 1.26-1.51 (overlapping peaks, 16H) , 0.91 (t, J = 7.0 Hz, 3H) .

1 ³ C NMR (75 MHz, CDC1 ₃ ) δ 142.41, 140.06,

139.97, 132.55, 132.53, 131.21, 131.19, 125.81, 123.31, 121.05, 53.13, 36.35, 36.11, 36.09, 36.04, 31.73, 31.64, 31.62, 29.41, 29.40, 29.32, 29.22, 28.98, 28.77, 26.73, 22.60, 14.08.

Anal. calcd. for C ₃₁ H ₄₀ Br2S ₂ : C, 58.49; H,

6.33; Br, 25.10; S, 10.07. Found: C, 58.30; H, 6.31; Br, 25.32; S, 9.98.

2-hexyl-7-undec-10-en-l-yl [1] benzothieno [3,2- b] [l]benzothiophene (8-1)

A mixture of compound 7-1 (0.93 g, 1.5 mmol) and Zn powder (0.48 g, 7.3 mmol) were added to glacial acetic acid (20 ml) . The reaction mixture was heated by microwave irradiation (50 mW) for 1-2 min without any stirring. The reaction mixture was then removed from the oven and cooled to room temperature. Water (100 ml) and dichloromethane (100 ml) were added to the reaction mixture and the organic layer was sepa- rated. The organic layer was washed with water and dried over sodium sulfate. Evaporation of the solvent give the pure compound 8-1 (.0.68 g, 98 %) .

¹ H NMR (250 MHz, CDC1 ₃ ) δ 7.77 (d, J = 8.2 Hz, 2H, ) , 7.71 (s, 2H) , 7.28 (dd, J = 8.2, J ₂ = 1.3 Hz, 2H) , 5.82 (m, 1H) , 4.97 (m, 2H) , 2.77(t, J = 7.5 Hz, 4H) , 2.05 (dd, J = 14.2, J ₂ = 6.8 Hz, 2H, ) , 1.72 (m, 4H) , 1.25-1.47 (overlapping peaks, 18H) , 0.91 (t, J = 7.0 Hz, 3H) . ¹³ C NMR (75 MHz, CDC1 ₃ ) δ 142.44, 140.06,

140.04, 139.22 132.57, 131.23, 131.19, 125.82, 123.31,

121.05, 114.09, 36.12, 33.80, 31.74, 31.65, 29.52, 29.50, 29.48, 29.30, 29.13, 28.99, 28.94, 22.60, 14.07.

Anal, calcd. for C ₃₁ H ₄₀ S2 : C, 78.09; H, 8.46; S, 13.45. Found: C, 78.21; H, 8.52; S, 13.42.

1- [11- (7-hexyl [1] benzothieno [3 , 2-b] [1] benzothien-2- yl) undecyl] -1 , 1 , 3 , 3-tetramethyldisiloxane (9-1)

Compound 8-1 (0.33 g, 0.7 mmol) was dissolved in the mixture of toluene (10 ml) and 1,1,3,3- tetramethyldisiloxane (5 ml) under argon, after which 25 μΐ of Karstedt's catalyst was added. The reaction was completed after 3 h of stirring at 50-60 °C. Evap- oration of the solvent give the pure compound 9-1 (0.42 g, 98 %) .

¹ H NMR (250 MHz, CDC1 ₃ ) <5 7.77 (d, J = 8.2 Hz, 2H, ) , 7.72 (s, 2H) , 7.28 (dd, J = 8.2, J ₂ = 1.3 Hz, 2H) , 4.71 (m, 1H) , 2.77(t, J = 7.5 Hz, 4H) , 1.72 (m, 4H), 1.25-1.47 (overlapping peaks, 22H) , 0.92 (t, J = 7.0 Hz, 3H) , 0.55 (t, J = 7.5 Hz, 2H) , 0.18 (d, J = 2.75, 6H) , 0.08 (s, 6H) .

¹³ C NMR (75 MHz, CDCI ₃ ) δ 142.42, 140.05, 132.55, 131.21, 125.81, 123.31, 121.05, 36.13, 33.39, 31.74, 31.70, 31.65, 2 9 . 62, 29.60, 29.54, 29.37, 29.33, 28.99, 23.91, 22.61 , _. 18.15 , 14.08 , 0.91, 0.05. ²⁹ Si NMR (60 MHz, CDC1 ₃ ) δ - 10.00, - 6.93.

Anal. calcd. for C ₃₅ H ₅₄ S2 S 12 : C, 68.79; H, 8.91; S, 10.49; Si, 9.19. Found: C, 68.72; H, 9.07; S, 10.44; Si, 9.10.

Chloro [10- (7-hexyl [1] benzothieno [3,2-b] [l]benzothien-

2-yl) decyl] dimethylsilane (Ia-1)

Compound 8-1 (0.1 g, 0.2 mmol) was dissolved in toluene (5 ml) and dimethylchlorosilane (DMCS, 0.4 g, 4.2 mmol) under argon, after which 10 μΐ of Karstedt's catalyst was added. The reaction was com- plete after 9 h of stirring at 40-50 °C. Evaporation of the solvent give 80% pure compound Ia-1 (0.11 g, 93 %) .

¹ H NMR (250 MHz , CDC1 ₃ ) δ 7.77 (d, J = 8.2 Hz, 2H, ) , 7.72 (s, 2H) , 7.28 (dd, J = 8.2, J ₂ = 1.3 Hz, 2H)., 2.77(t, J = 7.5 Hz, 4H) , 1.71 (m, 4H) , 1.21-1.47 (overlapping peaks, 22H) , 0.91 (t, J = 7.0 Hz, 3H) , 0.88 (m, 2H) , 0.41 (s, 6H) .

The morphology of monolayer of compound (Ia- 1) obtained with atomic-force microscopy (AFM) is de- mostrated in Fig. 8. The film thickness is 4 nm as seen from profile (Fig. 9), which corresponds to one molecular height of the compound (Ia-1) .

The transfer curve of the monolayer OFET based on compound (Ia-1) is shown in Fig. 8. The de- vice exhibits current modulation of 4 orders of mang- nitude between "open" and "closed" states. The meas- ured hole mobility is as high as 1.4xl0 ^~2 cm ² /Vs.

1 , 3-bis [11- (7-hexyl [1] benzothieno [3 ,2-b] [l]benzothien- 2-yl) undecyl] -1,1,3, 3-tetramethyldisiloxane (Ib-1)

Compound 8-1 (0.27 g, 0.6 mmol) and compound

9-1 (0.35 g, 0.6 mmol) were dissolved in anhydrous toluene (15 ml) under argon, and 25 μΐ of Karstedt's catalyst was then added. The reaction was complete af- ter the solution was stirred at 55 °C for 5 h. The re- action yield according to GPC analysis was 75%. The crude product was purified by a column chromatography on silica gel (eluent mixture toluene : hexane 1:10) to give the pure compound Ib-1 (0.38 g, 61 %) .

*H NMR (250 MHz , CDC1 ₃ ) δ 7.76 (d, J = 8.2 Hz, 4H, ) , 7.70 (s, 4H) , 7.28 (dd, J = 8.2, J ₂ = 1.3 Hz, 4H), 2.76 (t, J = 7.5 Hz, 8H) , 1.71 (m, 8H) , 1.22-1.47 (overlapping peaks, 44H) , 0.92 (t, J = 7.0 Hz, 6H) , 0.52 (t, J = 7.5 Hz, 4H) , 0.05 (s, 12H) .

¹³ C NMR (75 MHz, CDC1 ₃ ) δ 142.37, 140.02, 132.50, 131.15, 125.78, 123.28, 121.03, 36.11, 33.45, 31.73, 31.68, 29.72, 29.62, 29.'55, 29.42, 29.35, 28.99, 23.29, 22.61, 18.41, 14.11, 0.40.

²⁹ Si NMR (60 MHz, CDC1 ₃ ) δ 7.33.

Anal. calcd. for C ₆₆ H ₉₄ OS ₄ Si ₂ : C, 72.87; H, 8.71; S, 11.79; Si, 5.16. Found: C, 72.94; H, 8.81; S, 11.59; Si, 5.26.

The AFM scan of the monolayer of the compound (Ib-1) is shown in Fig. 6. The film thickness is also 4 nm (Fig. 7), which corresponds to one molecular height of compound (Ib-1) .

The transfer curve of the monolayer OFET based on compound (Ib-1) is shown in Fig. 9. The meas- ured on-off ratio of the device is 10 ³ , illustrating the successful device operation. The hole mobility is is 8.5xl0 ^-4 cm ² /Vs. The compound (Ib-1) is chemically stable which results in easy processing for solution processable electronics.

Although various aspects of the invention are set out in the independent claims, other aspects of the invention comprise other combinations of features from the described embodiments and/or the dependent claims with the features of the independent claims, and not solely the combinations explicitly set out in the claims .

It is also noted herein that while the above describes example embodiments of the invention, these descriptions should not be viewed in a limiting sense. Rather, there are several variations and modifications which may be made without departing from the scope of the present invention as defined in the appended claims .