Patent Application: US-201013511831-A

Abstract:
photoactive polymers comprising first and second co - monomer repeat units , the first co - monomer repeat unit comprising a moiety selected from the group consisting of an alkylthienopyrrole - 4 , 6 - dione moiety and a 1 , 3 - dithiophene - 5 - alkylthienopyrrole - 4 , 6 - dione moiety , and the second co - monomer repeat unit comprising a moiety selected from the group consisting of a 4 , 4 ′- dialkyl - dithienosilole moiety , an ethylene moiety , a thiophene moiety , an n - alkylcarbazole moiety , an n - dithienopyrrole moiety and a 4 , 8 - dialkyloxylbenzodithiophene moiety are described herein . these polymers are suitable for use in photovoltaic cells and field effect transistors .

Description:
in order to provide a clear and consistent understanding of the terms used in the present specification , a number of definitions are provided below . moreover , unless defined otherwise , all technical and scientific terms as used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this specification pertains . the use of the word “ a ” or “ an ” when used in conjunction with the term “ comprising ” in the claims and / or the specification may mean “ one ”, but it is also consistent with the meaning of “ one or more ”, “ at least one ”, and “ one or more than one ”. similarly , the word “ another ” may mean at least a second or more . as used in this specification and claim ( s ), the words “ comprising ” ( and any form of comprising , such as “ comprise ” and “ comprises ”), having ( and any form of having , such as “ have ” and “ has ”), “ including ” ( and any form of including , such as “ include ” and “ includes ”), or “ containing ” ( and any form of containing , such as “ contain ” and “ contains ”), are inclusive and open - ended and do not exclude additional , unrecited elements or process steps . the term “ about ” is used to indicate that a value includes an inherent variation of error for the device or the method being employed to determine the value . as used herein , the term “ alkyl ” can be straight - chain or branched . this also applies if they carry substituents or occur as substituents on other residues , for example in alkoxy residues , alkoxycarbonyl residues or arylalkyl residues . substituted alkyl residues can be substituted in any suitable position . examples of alkyl residues containing from 1 to 18 carbon atoms are methyl , ethyl , propyl , butyl , pentyl , hexyl , heptyl , octyl , nonyl , decyl , undecyl , dodecyl , tetradecyl , hexadecyl and octadecyl , the n - isomers of all these residues , isopropyl , isobutyl , isopentyl , neopentyl , isohexyl , isodecyl , 3 - methylpentyl , 2 , 3 , 4 - trimethylhexyl , sec - butyl , tert - butyl , or tert - pentyl . a specific group of alkyl residues is formed by the residues methyl , ethyl , n - propyl , isopropyl , n - butyl , isobutyl , sec - butyl and tert - butyl . as used herein , the term “ lower alkyl ” can be straight - chain or branched . this also applies if they carry substituents or occur as substituents on other residues , for example in alkoxy residues , alkoxycarbonyl residues or arylalkyl residues . substituted alkyl residues can be substituted in any suitable position . examples of lower alkyl residues containing from 1 to 6 carbon atoms are methyl , ethyl , propyl , isopropyl , butyl , isobutyl , tert - butyl , pentyl , isopentyl , neopentyl , and hexyl . in an embodiment , the present specification relates to thieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione and related compounds as electron accepter units to be copolymerized with electron donors for the manufacture of photoactive polymers useful in photovoltaic devices . the rigid structure of the thieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione unit enhances electron delocalization when incorporated into the conjugated backbone of photoactive polymers . it is believed that the rigid structure promotes interactions between polymer chains and improves the charge carrier mobility . moreover , the diketone functional group is a strong electron - withdrawing unit which is efficient in lowering the homo energy level to ensure high open circuit potentials . finally , positioning alkyl chains of various lengths on the nitrogen atom is susceptible to lead to highly soluble and easily processable materials . in an embodiment , the present specification relates to the synthesis and characterization [ x - ray scattering ( gixs ) and atomic force microscopy ( afm )] of polymers based on bdt and alkylated - tpd comonomers , with or without thiophene spacers . the thiophene units were added in order to tune the electronic properties and to enhance photon harvesting . in accordance with an embodiment of the present specification , various n - alkylated tbd derivatives were prepared using the synthetic route shown herein below in scheme 1 . in accordance with a further embodiment of the present specification , various additional n - alkylated tpd derivatives were obtained using the synthetic route shown herein below in scheme 2 . in accordance with an embodiment of the present specification , various electron donor units ( monomers ) to be co - polymerized with the tpd derivatives were prepared using the synthetic routes shown hereinbelow in schemes 3 - 5 . in accordance with an embodiment of the present specification , the synthesis of various polymers comprising a thieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione unit is disclosed hereinbelow in scheme 6 . all the polymers were prepared using the stille or suzuki cross - coupling reaction . polymerization yields , molecular weights and selected thermal properties of the polymers illustrated in scheme 6 are summarized hereinbelow in table 1 . the polymers were shown to be thermally stable having td values of over 400 ° c . some of the polymers such as zp25 , zp 37 or zp46 were not soluble in most common solvent or solvent systems . however , the solubility could be improved by varying the nature of the alkyl chain ( scheme 2 ). selected optical and electrochemical properties of the polymers illustrated in scheme 6 are summarized hereinbelow in table 2 . the optical properties were characterized by uv - vis - nir spectroscopy ( fig1 and 2 ). in solution , the uv - vis - nir absorption spectra show an absorbance ranging from 437 ( zp40 ) to 689 nm ( zp45 ) ( fig1 ). in the solid state , the uv - vis - nir absorption spectra show an absorbance ranging from 530 ( zp40 ) to 840 nm ( zp45 ) ( fig2 ). the absorption spectra of the novel photoactive polymers of the present specification are thus located in the ideal range of the solar emission spectra . cyclic voltammetry measurements were performed ( fig3 ) in order to estimate the homo / lumo energy levels and the bandgap of the polymers illustrated in scheme 6 . the electrochemical bandgaps were shown to range between 1 . 53 ev ( zp45 ) and 2 . 18 ev ( zp40 ). the homo energy levels were shown to range between − 5 . 21 ev ( zp36 ) and − 5 . 90 ev ( zp45 ), which means that the polymers , with the exception of zp36 , can be considered as being air - stable ( fig4 ). the lumo energy levels were shown to be located at energy levels conducive to efficient electron transfer and were measured to range between − 3 . 71 ev ( zp35 ) and − 3 . 99 ev ( zp25 ) ( fig4 ). by using the scharber model [ 18 ], almost all of the polymers illustrated in scheme 6 illustrated a theoretical power conversion efficiency ( pce ) of more than 7 % ( fig5 ). zp - 25 and zp - 28 exhibited a pce of near 10 %. preliminary screening using zp30 , zp46 , zp50 and zp51 as the active layer in bhj photovoltaic cells was performed and the results summarized hereinbelow in table 3 . the voc values were determined to be relatively high for all the polymers illustrated in scheme 6 . zp46 was determined to exhibit a pce of 3 . 3 % for non - optimized devices . it is of interest to note that the thieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione - based polymers of the present specification can be used in conjunction with additional electron acceptors , non - limiting examples of which include pcbm ( c60 or c70 ) ( fig6 ). the preliminary results obtained for the photovoltaic devices comprising at least one of the polymers as illustrated in scheme 6 can be explained by good structural organization at room temperature . the x - ray diffraction patterns for polymers zp30 , zp46 , zp50 and zp51 are illustrated in fig7 . the polymers show several diffraction peaks at room temperature which is indicative of some degree of organization . the peak intensity increased and sharpened upon heating . the diffraction planes localized around 9 and 3 . 6 å are attributed to interlayer and n - stacking spacing respectively , which implies a higher degree of organization [ 19 ]. preliminary measurements on zp30 revealed a hole mobility of about 0 . 01 cm 2 / v . s . in accordance with an embodiment of the present specification , the bulk heterojunction photovoltaic solar cell ( pscs ) were fabricated using the following structure : glass / ito / pedot : pss / polymer : pcbm / a1 ( fig1 ). a commercial indium tin oxide ( ito )- coated glass substrate ( 24 × 24 mm 2 ) with a sheet resistance of ≦ 10 ohms / sq ( prazisions glass optic gmbh , germany ), was cleaned by ultrasonication using soap , water , acetone and 2 - propanol respectively . following a 5 minute plasma - o 2 treatment , the ito substrate was patterned using photolithography . poly ( 3 , 4 - ethylenedioxythiophene ): poly ( stryrenesulphonate ) ( pedot - pss , baytron p , h . c . starck ) was spin - coated ( 2000 rpm , 60 s ) onto the ito surface and dried at 120 ° c . over a period of 1 h . following cooling , an orthodichlorobenzene ( odcb ) solution of polymer /[ 6 , 6 ]- phenyl - butyric acid methyl ester ( pcbm ) ( nano - c , usa ) was spin - coated onto the substrate . the substrate was subsequently placed into a thermal evaporation chamber . a 70 nm thick aluminum electrode ( 0 . 3 - 0 . 4 nm / s ) was then deposited under high vacuum ( 2 × 10 − 5 torr ; the active area is 25 mm 2 ). the current - voltage characteristics of the photovoltaic cells were measured using a kheithey 2400 ( i - v ) digital sourcemeter under a collimated beam . the measurements were conducted under the irradiation of am 1 . 5 g simulated solar light ( 100 mw cm − 2 ; filter # 81094 ) using a 150 w oriel instruments solar simulator and a xenon lamp . the light intensity was adjusted using a gentec - eo power detector ( ps - 330 ). since the thickness of the active layer may be a critical issue for a reliable roll - to - toll processing of bulk heterojunction ( bhj ) solar cells , both thin and thick active layers were investigated using a 25 mm 2 active area . in accordance with an embodiment of the present specification , bulk heterojunction photovoltaic solar cells were fabricated using the following structure : glass / ito / pedot : pss / polymer :[ 60 ] pcbm / a1 as illustrated in fig1 . commercial indium tin oxide ( ito - coated glass substrate ( 25 × 25 mm 2 ) with a sheet resistance of ≦ 10 ohms / sq ( prazisions glas optic gmbh , germany ) were cleaned using following sequence in an ultrasonic bath : detergent , water , acetone and 2 - propanol . after treatments in plasma - o 2 for 5 minutes , each ito substrate was patterned using photolithography techniques . then poly ( 3 , 4 - ethylenedioxythiophene ): poly ( styrenesulphonate ) ( pedot - pss , baytron p , h . c . starck ) was spin - coated ( 2000 rpm , 60 s ) on ito surface and dried at 120 ° c . for 1 h . after cooling the substrate , a ortho - dichlorobenzene ( o - dcb ) solution of polymer and [ 6 , 6 ]- phenyl - c 61 butyric acid methyl ester ([ 60 ] pcbm ) ( nano - c , usa ) mixture ( 1 : 2 , wt / wt ) was spin - coated . the substrates were then put in a thermal evaporation chamber , in order to evaporated 70 nm of aluminum layer ( 0 . 2 - 0 . 3 nm per second ) under high vacuum ( 2 × 10 − 5 torr ) through a shadow mask ( active area 25 mm 2 ). the current - voltage characteristics of the photovoltaic cells were measured using a kheithey 2400 ( i - v ) digital sourcemeter under a collimated beam . the measurements were conducted under the irradiation of am 1 . 5 g filter ( no 81094 ) simulated solar light ( 100 mw cm − 2 ) by using a 150 w oriel instruments solar simulator and xenon lamp . light intensity was adjusted using a gentec - eo power detector ( ps - 330 ). in accordance with an embodiment of the present specification , various additional n - alkylated tbd derivatives were prepared using the synthetic route shown herein below in scheme 7 . previous work on bdt - tpd polymers and bdt - based polymers revealed that benzo [ 1 , 2 - b : 3 , 4 - b ] dithiophene ( bdt ) bearing an ethylhexyl side chain leads to soluble polymers having high molecular weights , enhanced morphology for films obtained from polymer /[ 60 ] pcbm blends , and high power conversion efficiency in bulk heterojunction ( bhj ) solar cells [ 20 - 23 ]. since the presence of alkyl side chains on the tpd unit can also influence the solubility , molecular weight , organization , and charge mobility of bdt - tpd based polymers , polymers p1 , p2 and p3 were prepared ( scheme 8 ) and the morphology of the polymer /[ 60 ] pcbm blends investigated . the preparation of additional bdt - tpd based polymers comprising a thiophene spacer ( p4 , p5 and p6 ); comprising a thiophene spacer having alkyl chains facing the tpd unit ( p7 , p8 and p10 ); and comprising a thiophene spacer having alkyl chains facing the bdt unit ( p9 and p11 ) is shown herein below in scheme 8 . stille coupling of monomers 4 - 6 and the bdt comonomer yielded soluble polymers of moderate molecular weights . the solubility of the polymers comprising unsubstituted thiophene spacers was dramatically reduced when compared to p1 - p3 . polymers p4 and p6 were insoluble in common organic solvents . however , modifying the n - alkyl group of the tbd unit from a straight alkyl chain to a branched alkyl chain ( i . e . ethylhexyl ) results in a soluble and processable polymer ( p5 ) of moderate molecular weight . polymerization of the monomeric unit obtained by stille coupling of monomers 22 - 26 and the bdt comonomer afforded soluble materials with high molecular weights . polymers ( p1 - p11 ) were characterized by size exclusion chromatography ( sec ) using monodisperse polystyrene in hot 1 , 2 , 4 - trichlorobenzene ( tcb ) as the standard . the data are summarized hereinbelow in table 4 . the number - average molecular weight ( m n ) ranges from 8 . 3 kda ( p5 ) to 131 kda ( p7 ) with a polydispersity index ( pdi ) ranging between 1 . 5 ( p5 ) and 3 . 2 ( p8 ). thermogravimetric analyses ( tga ) showed that all polymers are thermally stable with degradation temperature ( t d ) ranging from 330 to 380 ° c . with the exception of p1 ( t g = 138 ° c . ), differential scanning calorimetry ( dsc ) did not reveal any noticeable glass transition temperatures ( p2 - p11 ). all polymeric materials ( p1 - p11 ) exhibit a broad absorption spectra indicative of a large part of the solar spectral flux being absorbed ( fig1 ). these absorption characteristics should contribute to obtaining high short circuit current ( jo values in bhj solar cells . the absorption spectra of p1 , p2 , p3 , and p5 remain almost the same in going from solution to film ( fig1 b ). dft ( density functional theory ) calculations performed on p1 - p3 revealed coplanar structures ( data not shown ). moreover , neither the length nor the type of the tail chain on the thieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione ( tpd ) unit seems to affect the optical properties of these polymers ( p1 - p11 ). absorption spectra obtained for a film comprising p5 showed that the thiophene spacers ( without alkyl chains ) did not modulate the optical properties ; the optical band gap remaining the same as for p1 - p3 . polymers p7 - p11 displayed significant red shifts ( up to 40 nm for p8 ) in going from solution to film . this behaviour observed in dense thin films of conjugated polymers is due to an increase in the conjugation length due to an ordering in the solid state . however , the absorption spectra of these polymers were blue shifted when compared to p1 - p3 ; again the optical band gap remains almost the same . it can be readily observed that only a small range in the optical band gap ( onset of the absorption spectra ) was obtained for polymers p1 - p11 , meaning that the influence of the thiophene spacer on the optical properties is somehow limited . cyclic voltammetry measurements were performed in order to estimate the homo / lumo energy levels and the bandgap of polymers p1 - p11 ( fig1 ; table 4 ). the homo energy levels were estimated by using the onset of the oxidation potential ( all polymers showed non - reversible oxidation processes ). on the other hand , all polymers showed reversible reduction processes . the lumo energy levels were estimated in a manner similar to that used to estimate the homo energy levels . as observed regarding the optical properties , modifying the n - alkyl group of the tbd unit did not have a significant impact on the electronic properties . the relatively deep homo energy levels should contribute to achieve high v oc values in bhj photovoltaic cells while the lumo energy levels are within the desirable range for proper electron transfer from the donor to the electron acceptor ([ 60 ] pcbm ). in accordance with an embodiment of the present specification , the photovoltaic properties of polymers p1 - p11 were investigated in bhj solar cells comprising the following configuration : glass / ito / pedot : pss / active layer / al ( fig1 ). the active layer comprised a blend of at least one of p1 - p11 with [ 60 ] pcbm , spin - coated from chloroform or ortho - dichlorobenzene ( o - dcb ) solutions . for p1 and p10 , both thin and relatively thick active layers were prepared . the ratio of donor / acceptor was optimized and found to be 1 : 2 ( wt / wt ) for all polymers , excepted for p2 ( 1 : 1 ). solar cells were tested under am 1 . 5 g ( am = air mass ) illumination of 100 mw cm − 2 and the active area of the devices were 25 mm 2 ( table 5 ). j - v curves are shown in fig1 and data on the bhj solar cells are summarized hereinbelow in table 5 . where i 0 is the dark current , e is the electron charge , n is the diode ideality factor , v is the applied voltage , r s is the series resistance , r sh is the shunt resistance , and i ph is the photocurrent . r s and r sh can be described by the following equations : thus , to obtain high short - circuit currents , i sc ( v = 0 ), solar - cell devices must have small r s and large r sh values . from a physical point of view , the series resistance r s can be associated to materials conductivity , thus the charge carrier mobility in the donor / acceptor blends ( electron mobility in the acceptor and hole mobility in the donor ). r sh interprets the charge recombination close to dissociation charge sites ( interface d / a and electrodes ). p1 and p3 show the best photovoltaic performances with high v oc values ( 0 . 94 v and 0 . 96 v respectively ), and short circuit current density ( j sc ) values ( 10 . 8 ma . cm − 2 and 10 . 0 ma . cm − 2 respectively ). moderate fill factor ( ff ) values approaching 51 % for both polymers afforded power conversion efficiencies ( pce ) of 5 . 2 % ( p1 ) and 4 . 8 % ( p3 ). since high - speed roll - to - toll manufacturing processes can be used to print polymeric solar cells , the use of relatively thick films is important in order to get uniform and defect free active layers . while the v oc and j sc values remain substantially unchanged when varying the thickness of the film devices , the ff values drop by more than 20 %. despite this fact , the pce reported herein for p1 is among the highest values reported in the literature for thick layer bhj solar cells . according to data reported in table 5 , varying the length of the n - alkyl group of the tpd unit from octyl to docecyl led to a lower pce ( 4 . 8 %). this lower value is caused by a drop of the j sc value even though the shunt resistance ( r sh ) was higher for p3 ( 1163 ωcm 2 ) than for p1 ( 994 ωcm 2 ). the bdt - tpd derivatives comprising thiophene spacers having alkyl chains facing the tpd unit also revealed promising photovoltaic results ( p7 , p8 , and p10 ). among these polymers , p7 gave the best photovoltaic results with a power conversion efficiency of 3 . 9 % ( thickness of 102 nm ). p10 ( with c 12 h 25 on the tpd unit ) reached a pce of 3 . 6 % with a v oc of 0 . 87 v and a ff of 58 %. data reported in table 5 are indicative of devices comprising p7 being superior to ones comprising p8 and p10 due to a higher shunt resistance value ( r sh = 1904 ωcm 2 ). for p10 , a lower shunt resistance causes power losses in solar cells by providing an alternate current path for the light - generated current . however , when used in a thick film configuration ( 165 nm ), p10 shows a high v oc ( 0 . 88v ) and a pce of 3 . 1 %. as for p1 and p3 , the length of the n - alkyl chain causes a small drop in the short circuit current j sc , which is probably due to the morphology of the blend with the [ 60 ] pcbm . p8 was prepared to get soluble polymers having a short alkyl chain on the thiophene spacer ( p4 and p6 being insoluble in most common organic solvents ). despite a high j sc of 9 . 0 ma / cm 2 , a drop of the v oc of 0 . 13v ( compared to p7 ) led to a pce of 3 . 5 %. bdt - tpd derivatives comprising thiophene spacers bearing alkyl chains facing the bdt unit revealed deficient photovoltaic results ( p9 and p11 ). pces of 0 . 2 % and 0 . 7 % for p9 and p11 respectively were observed . moreover , for both polymers , the j sc and ff values were low . this can be explained by the nanoscale morphology observed using atomic force microscopy ( afm ). while the nanoscale morphology of blends of p1 - p5 ; p7 , p8 and p10 with [ 60 ] pcbm are quite similar with only small variations in the roughness on the surface , p9 and p11 revealed a somehow unique morphology . as shown in fig1 , “ donut ” shapes with a diameter of 500 nm were observed . the percolation pathways are poorly formed limiting the transport of the charges to the respective electrodes in turn leading to poor short circuit current j 5 values . to confirm these assumptions , the effect of the n - alkyl chain on the tpd unit ( p1 - p3 ) and the effect of the thiophene spacer ( with or without alkyl chains ) ( p5 - p11 ) on the molecular organization in polymer thin films was investigated using grazing - incidence x - ray scattering ( gixs ). p1 - p11 /[ 60 ] pcbm gixs analyses were conducted on glass / ito / pedot - pss solid supports . as shown in fig1 , a peak at 4 . 2 å was observed for all polymer /[ 60 ] pcbm blends . this peak corresponds to the distance between the coplanar π - conjugated backbones . the fact that the 7 ′- stacking peak could be observed for the entire bdt - tpd series , is indicative of these polymers being able to retain the same face - on orientation when blended with the electron acceptor ([ 60 ] pcbm ). for p1 - p3 , an additional peak corresponding to lamellar spacing could be observed . since this distance is related to the length of the n - alkyl chain , it is longer for the dodecyl derivative p3 ( 24 . 6 å ) than for the octyl p1 ( 21 . 2 å ) and ethylhexyl derivatives p2 ( 18 . 6 å ). these peaks were also present for p8 ( d 1 = 17 . 3 å ) and p10 ( d 1 = 20 . 6 å ). one can surmise that the shorter distance observed for p8 ( ethyl on the thiophene spacer ) leads to better order in the blend which results in higher j sc ( 9 . 0 ma / cm 2 ) values in bhj solar cells when compared to p10 ( j sc = 7 . 2 ma / cm 2 ). on the other hand , while p7 afforded good power conversion efficiency ( 3 . 9 %), the gixs diffractogram did not show any lamellar distance related peaks as for the less efficient bdt - tpd derivatives ( p5 , p9 and p11 ). preliminary results on the photovoltaic devices revealed that the length of the n - alkyl chain of the tpd unit has an impact on the morphology of the polymers /[ 60 ] pcbm blends . power conversion efficiencies of 5 . 2 % have been obtained for a thin layer of p1 . moreover , thick active layer bhj solar cells have been studied and pce values of up to 3 . 8 % were reached with p1 . this result is among the highest pce values reported so far for relatively thick films . a number of examples are provided herein below illustrating the efficiency of the photoactive polymers of the present specification . thiophene - 3 , 4 - dicarboxylic acid was purchased from frontier scientific . 2 -( tributylstannyl ) thiophene was purchased from aldrich . tetrabutylammonium tetrafluoborate ( nbu 4 bf 4 ) ( 98 %, aldrich ) was recrystallized three times in a 50 : 50 mixture of methanol / water and dried at 100 ° c . n - bromosuccinimide ( nbs ) was recrystallized from water prior to use . all reactions were carried out under argon unless otherwise stated . the reaction solvents were dried prior to use ( thf from sodium / benzophenone , toluene and acetonitrile from cah 2 ) unless otherwise stated . column chromatography was carried out on silica gel ( 300 - 400 mesh ). the synthesis of 5 - octylthieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione , 1 , 3 - dibromo - 5 - octyl - thieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione ( 4 ), 2 - trimethyltin thiophene ( 7 ), 2 -( trimethyltin )- 3 - octylthiophene ( 8 ), 2 -( trimethyltin )- 4 - octylthiophene ( 10 ) and 2 , 6 - bis ( trimethyltin )- 4 , 8 - di ( 2 - ethylhexyloxyl ) benzo [ 1 , 2 - b : 3 , 4 - b ] dithiophene involved known literature procedures . all the monomers were carefully purified prior to use in the polymerization reaction . all other compounds were synthesized following the procedures described herein . 1 h nmr or 13 c nmr spectra were recorded using a varian as400 ( 400 mhz ) or brucker ac300 ( 300 mhz ) in a deuterated chloroform , dimethyl sulfoxide , tetrahydrofuran or acetone solution at 298 k . chemical shifts were reported as δ values ( ppm ) relative to an internal tetramethylsilane ( tms ) standard . number - average ( m n ) and weight - average ( m w ) molecular weights were determined by size exclusion chromatography ( sec ) using a high pressure liquid chromatography ( hplc ) pump ( waters 515 pump ), two shodex kf - 804 columns ( particle size 7 μm , 8 . 0 mm id × 300 mm ), and chloroform ( chcl 3 )( hplc grade , aldrich ) as eluant and using a waters 441 uv - vis detector . alternatively , number - average ( m n ) and weight - average ( m w ) molecular weights were determined by size exclusion chromatography ( sec ) using a high temperature varian polymer laboratories gpc220 equipped with an ri detector and a pl bv400 ht bridge viscometer . the column set consists of 2 plgel mixed c ( 300 × 7 . 5 mm ) columns and a plgel mixed c guard column . the flow rate was fixed at 1 . 0 ml / min using 1 , 2 , 4 - trichlorobenzene ( tcb ) ( with 0 . 0125 % bht w / v ) as eluant . the temperature of the system was set to 140 ° c . the sample was prepared at concentration of nominally 1 . 0 mg / ml in hot tcb . dissolution was performed using a varian polymer laboratories pl - sp 260vc sample preparation system . the sample vial was held at 160 ° c . with shaking for 1 h for complete dissolution . the solution was filtered through a 2 μm porous stainless steel filter used with the sp260 pipettor into a 2 ml chromatography vial . the calibration method used to generate the reported data was the classical polystyrene method using polystyrene narrow standards easi - vials ps - m from varian polymer laboratories which were dissolved in tcb . thermogravimetric analysis ( tga ) measurements were carried out using a mettler toledo tga sdta 851e apparatus at a heating rate of 20 ° c ./ min under nitrogen . the temperature of degradation ( t d ) corresponds to a 5 % weight loss . differential scanning calorimetric ( dsc ) analysis was performed on a perkin - elmer dsc - 7 instrument , calibrated with ultra pure indium . glass transition temperatures ( t g ) were measured at a scanning rate of 20 ° c ./ min , under a nitrogen flow . uv - vis - nir absorption spectra were taken using a varian cary 500 uv - vis - nir spectrophotometer using 1 cm path length quartz cells . spin - coated films on glass plates were used for solid - state uv - vis - nir measurements ( a polymer solution in chloroform was spin coated on quartz plates ). optical bandgaps were determined from the onset of the absorption band . cyclic voltammograms ( cv ) were recorded on a solartron 1287 potentiostat using platinum electrodes , at a scan rate of 50 mvs − 1 and a ag / ag + reference electrode ( 0 . 1 m of agno 3 in acetonitrile ) in an anhydrous and argon - saturated solution of 0 . 1 m of tetrabutylammonium tetrafluoborate ( bu 4 nbf 4 ) in acetonitrile ( electrolyte ). under these conditions , the oxidation potential ( e ox ) of ferrocene was 0 . 09v versus ag / ag + , whereas the e ox of ferrocene was 0 . 41 v versus sce . the homo and lumo energy levels were determined from the oxidation and reduction onset from the cv spectra assuming the sce electrode to be − 4 . 7 ev from vacuum . electrochemical onsets were determined at the position where the current starts to differ from the baseline . a nanoscope iii , dimension 3100 , atomic force microscope ( digital instrument ) was used to determine the thickness . to determine the thickness , each film was indented with a razor blade and topographic images were recorded by afm ; the thickness of the film was taken as the difference between the height of the film surface ( an average made on both sides of the indentation ) relative to the surface of the substrate ( at the bottom of the indentation ). grazing - incidence x - ray scattering ( gixs ) experiments were performed using a siemens d5000 x - ray diffractometer with a cuka radiation source ( 1 . 540598 å ). the operation power was 40 kv , 30 ma . the surface topographies of bhj active layers composed of donor polymers and [ 60 ] pcbm were obtained with an atomic force microscopy ( afm ) in tapping mode ( dimension v spm , veeco ). the si afm tip was used with a force constant of 42 n m − 1 and afm images were collected in air under ambient conditions . a stirred solution of 3 , 4 - bromothiophene ( 48 . 2 g , 0 . 2 mol ) and cuprous cyanide ( 54 g , 0 . 6 mol ) in dimethylformamide ( 100 ml ) in a 250 ml flask was heated to 140 ° c ., over a period ranging from 12 - 24 h . the reaction mixture was allowed to cool and was subsequently poured into a large amount of diluted ammonium hydroxide and stirred overnight . the reaction mixture was extracted with chloroform ( 4 × 1000 ml ) and filtered . the combined organic extracts were washed twice with water . the organic phase was dried over anhydrous magnesium sulfate . following the removal of the solvent a light - yellow solid was obtained which was subsequently purified by column chromatography using hexanes : ethyl acetate ( 1 : 1 ) as the eluant . a white product was obtained ( 12 g , yield : 45 %): mp : 170 - 171 ° c . ; gc - ms : 134 ; 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 8 . 06 ( s , 2h ); 13 c nmr ( 400 mhz , cdcl 3 , ppm ) δ : 136 . 8 , 113 . 2 , 112 . 3 , 4 - dicyanothiophene ( 8 . 84 g , 66 mmol ) and potassium hydroxide ( 34 g , 0 . 6 mol ) were dissolved in ethylene glycol ( 100 ml ) and refluxed overnight . the light yellow reaction mixture was cooled and poured into water ( 600 ml ). the resulting solution was extracted with diethyl ether ( 2 × 400 ml ), and the aqueous phase was cooled in an ice bath and acidified with excess concentrated hydrochloric acid until ph & lt ; 3 . the acidified aqueous phase was subsequently extracted with diethyl ether ( 2 × 400 ml ). the combined organic extracts were dried over anhydrous magnesium sulfate and concentrated to afford the crude product as brown crystals . recrystallization from water afforded thiophene - 3 , 4 - dicarboxylic acid ( 9 . 06 g , yield : 83 %): mp : 230 - 232 ° c . ; 1 h nmr ( 400 mhz , dmso - d 6 , ppm ) δ : 8 . 11 ( s , 2h ); 13 c nmr ( 100 mhz , dmso - d 6 , ppm ) δ : 165 . 1 , 134 . 3 , 133 . a solution of thiophene - 3 , 4 - dicarboxylic acid ( 5 . 97 g , 34 . 77 mmol ) in acetic anhydride ( 150 ml ) was stirred overnight at 140 ° c . the reaction mixture was subsequently concentrated to yield thiophene - 3 , 4 - dicarboxylic anhydride as a brown solid which was used without further purification . gc - ms : 154 ; 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 8 . 09 ( s , 2h ). the anhydride was subsequently dissolved in toluene ( 320 ml ) in a 500 ml flask , followed by the addition of n - octylamine ( 6 . 72 g , 52 . 02 mmol , 8 . 6 ml ). the resulting reaction mixture was subsequently refluxed over a period of 24 h . the reaction mixture was allowed to cool and was subsequently concentrated affording 4 - octylcarbamoylthiophene - 3 - carboxylic acid as a solid . the acid was dissolved in thionyl chloride ( socl 2 ) ( 270 ml ) and refluxed over a period of 4 hours . the reaction mixture was cooled down and subsequently concentrated to dryness . the residue was purified by column chromatography using methylene dichloride : hexanes ( 2 : 1 ) as the eluant to afford the title compound as a pure white solid ( 5 . 2 g , yield 57 %): mp : 120 - 122 ° c . ; gc - ms : 265 ; 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 8 ( s , 2h ), 3 . 62 - 3 . 59 ( t , 2h ), 1 . 64 - 1 . 62 ( m , 2h ), 1 . 26 ( m , 10h ), 0 . 87 - 0 . 85 ( m , 3h ); 13 c nmr ( 100 mhz , cdcl 3 , ppm ) δ : 162 . 4 , 136 . 7 , 125 . 2 , 37 . 9 , 31 . 7 , 29 . 2 ( 2c ), 28 . 4 , 26 . 8 , 22 . 4 , 14 . 1 . 5 - octylthieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione ( 2 . 66 g , 10 mmol ) was dissolved in concentrated sulfuric acid ( 15 . 3 ml ) and trifluoroacetic acid ( 50 ml ). nbs ( 5 . 37 g , 30 mmol ) was subsequently added in five portions and the reaction mixture was stirred at room temperature overnight . the brown - red solution was then slowly diluted with water ( 100 ml ) and extracted with dichloromethane . the organic phase was dried over anhydrous magnesium sulfate and concentrated to afford the crude product as orange crystals . purification by column chromatography using methylene dichloride : hexanes ( 1 : 1 ) as the eluant afforded the title compound as a white powder ( 3 . 4 g , yield : 81 %): mp : 104 ° c . ; 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 3 . 61 - 3 . 57 ( t , 2h ), 1 . 62 - 1 . 56 ( m , 2h ), 1 . 29 - 1 . 26 ( m , 10h ), 0 . 89 - 0 . 85 ( t , 3h ); 13 c nmr ( 100 mhz , cdcl 3 , ppm ) δ : 160 . 6 , 138 . 7 , 113 . 2 , 39 . 1 , 32 , 29 . 4 , 29 . 36 , 29 . 33 , 28 . 5 , 27 . 02 , 27 , 22 . 8 , 14 . 3 . a solution of thiophene - 3 , 4 - dicarboxylic acid ( 0 . 90 g , 5 . 23 mmol ) in acetic anhydride ( 21 ml ) was stirred overnight at 140 ° c . the reaction mixture was subsequently concentrated to yield thiophene - 3 , 4 - dicarboxylic anhydride as a brown solid which was used without further purification . the anhydride was subsequently dissolved in toluene ( 55 ml ) in a 100 ml flask , followed by the addition of 2 - ethylhexylamine ( 1 . 02 g , 7 . 85 mmol ). the resulting reaction mixture was subsequently refluxed over a period of 24 h . the reaction mixture was allowed to cool and was subsequently concentrated affording the desired acid as a solid . the acid was subsequently dissolved in thionyl chloride ( socl 2 ) ( 68 ml ) and refluxed over a period of 3 hours . the reaction mixture was cooled down and subsequently concentrated to dryness . the residue was purified by column chromatography using methylene dichloride : hexanes ( 1 : 1 ) as the eluant to afford the title compound as a pure white solid ( 0 . 9 g , yield : 65 %): 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 78 ( s , 2h ), 3 . 48 - 3 . 46 ( t , 2h ), 1 . 78 - 1 . 75 ( t , 1h ), 1 . 32 - 1 . 24 ( m , 8h ), 0 . 90 - 0 . 82 ( t , 6h ). 13 c nmr ( 100 mhz , cdcl 3 , ppm ) δ : 163 . 16 ; 136 . 81 ; 125 . 71 ; 42 . 54 ; 38 . 35 ; 30 . 67 ; 28 . 67 ; 24 . 00 ; 23 . 23 ; 14 . 30 ; 10 . 62 . the title compound was synthesized as described hereinabove using thiophene - 3 , 4 - dicarboxylic acid ( 10 . 00 g , 58 . 08 mmol ) and 1 - dodecylamine ( 16 . 14 g , 87 . 12 mmol ) to afford 10 . 27 g of the title product as a white solid ( y = 55 %). 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 80 ( s , 2h ); 3 . 60 ( t , 2h , j = 7 . 3 hz ); 1 . 65 - 1 . 62 ( m , 2h ); 1 . 30 - 1 . 24 ( m , 18h ); 0 . 87 ( t , 3h , j = 6 . 5 hz ); 13 c nmr ( 100 mhz , cdcl 3 , ppm ) δ : 162 . 92 ; 136 . 91 ; 125 . 71 ; 38 . 75 ; 32 . 15 ; 29 . 87 ; 29 . 85 ; 29 . 81 ; 29 . 75 ; 29 . 59 ; 29 . 45 ; 28 . 72 ; 27 . 12 ; 22 . 93 ; 14 . 39 . 5 -( 2 - ethylhexyl ) thieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione ( 0 . 45 g , 1 . 7 mmol ) was dissolved in concentrated sulfuric acid ( 2 . 6 ml ) and trifluoroacetic acid ( 8 . 7 ml ). nbs ( 0 . 94 g , 5 . 1 mmol ) was subsequently added in four portions and the reaction mixture was stirred at room temperature overnight under darkness . the brown - red solution was then slowly diluted with water ( 20 ml ) and extracted with dichloromethane . the organic phase was dried over anhydrous magnesium sulfate and concentrated to afford the crude product as orange crystals . purification by column chromatography using methylene dichloride : hexanes ( 1 . 5 : 1 ) as the eluant afforded the title compound as a white powder ( 1 . 0 g , yield : 78 %): 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 3 . 5 - 3 . 48 ( d , 2h ), 1 . 8 ( m , 1h ), 1 . 34 - 1 . 27 ( m , 8h ), 0 . 92 - 0 . 87 ( t . 6h ); 13 c nmr ( 100 mhz , cdcl 3 , ppm ) δ : 160 . 92 ; 134 . 95 ; 113 . 18 ; 42 . 86 ; 38 . 40 ; 30 . 74 ; 28 . 77 ; 24 . 05 ; 23 . 18 ; 14 . 32 ; 10 . 60 . the title compound was synthesized as described for 5 using 5 -( dodecyl )- thieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione ( 3 . 00 g . 9 . 32 mmol ), a mixture of sulfuric acid ( 17 . 4 ml ) and trifluoroacetic acid ( 56 . 4 ml ) and n - bromosuccinimide ( 4 . 44 g , 24 . 94 mmol ) to afford 3 . 03 g of the title product as white powder ( y = 68 %). 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 3 . 59 ( t , 2h , j = 7 . 2 hz ); 1 . 64 - 1 . 61 ( m , 2h ); 1 . 30 - 1 . 25 ( m , 18h ); 0 . 87 ( t , 3h , j = 6 . 5 hz ). 13 c nmr ( 100 mhz , cdcl 3 , ppm ) δ : 160 . 63 ; 135 . 03 ; 113 . 17 ; 39 . 08 ; 32 . 16 ; 29 . 86 ; 29 . 84 ; 29 . 81 ; 29 . 69 ; 29 . 59 ; 29 . 40 ; 28 . 50 ; 27 . 04 ; 22 . 94 ; 14 . 38 . 1 , 3 - dibromo - 5 - octylthieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione ( 2 . 1 g , 5 mmol ) was dissolved in thf ( 200 ml ) in a 500 ml flask , followed by the addition of tributyltin thiophene ( 5 . 6 g , 4 . 8 ml ) and pd ( pph 3 ) 2 cl 2 ( 210 mg , 6 %). the resulting reaction mixture was subsequently refluxed over a period of 24 h . the reaction mixture was allowed to cool and was subsequently treated with an aqueous kf solution ( 100 ml ). the reaction mixture was then extracted with dichloromethane ( 250 ml ). the organic phase was dried and concentrated to afford the crude product as a yellow - green residue . purification by column chromatography using methylene dichloride : hexanes ( 1 : 1 ) as the eluant afforded the title compound as a green powder ( 1 . 6 g , yield : 75 %): r f ( dcm : hexanes ( 1 : 1 ))= 0 . 6 ; 1 h nmr ( 400 mhz , d 8 - thf , ppm ) δ : 8 . 33 - 8 . 32 ( d , 2h ), 7 . 78 - 7 . 77 ( d , 2h ), 7 . 34 - 7 . 32 ( t , 2h ), 3 . 83 ( t , 2h ), 1 . 89 ( m , 2h ), 1 . 53 - 1 . 47 ( m , 10h ), 1 . 05 ( t , 3h ); 13 c nmr ( 100 mhz , d 8 - thf ) δ : 162 . 1 , 135 . 7 , 132 . 5 , 1 30 . 1 , 129 . 1 , 128 . 9 , 128 . 4 , 38 . 1 , 32 , 28 . 9 , 28 . 4 , 26 . 9 , 22 . 7 , 13 . 6 . 1 , 3 - dithiophene - 5 - octylthieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione ( 0 . 86 g , 2 mmol ) was dissolved in a mixture of acoh and chcl 3 ( 30 ml : 30 ml ) in a 100 ml flask placed in an ice bath . nbs ( 0 . 79 g , 4 . 4 mmol ) was subsequently added in several portions and the reaction mixture was stirred at room temperature over a period of 24 h . the solution was then slowly diluted with water and extracted with chloroform ( 200 ml ). the organic phase was dried and concentrated to afford a crude residue which was purified by column chromatography using methylene dichloride : hexanes ( 1 : 1 ) as the eluant . the title compound was obtained as a bright yellow powder ( 1 . 16 g , yield : 99 %): 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 65 ( d , 2h ), 7 . 09 - 7 . 08 ( d , 2h ), 3 . 64 ( t , 2h ), 1 . 67 ( m , 2h ), 1 . 32 - 1 . 26 ( m , 10h ), 0 . 89 - 0 . 85 ( t , 3h ). 3 - octylthiophene ( 45 g ) was dissolved in dmf ( 327 ml ). nbs ( 40 . 75 g ) was dissolved in dmf ( 300 ml ) and was subsequently added dropped to the 3 - octylthiophene solution at room temperature under the darkness . the reaction mixture was subsequently stirred at room temperature overnight , slowly diluted with water ( 800 ml ) and extracted with diethyl ether ( 3 × 300 ml ). the combined organic extracts were subsequently washed with brine ( 2 × 200 ml ) and water ( 200 ml ). the organic phase was dried over anhydrous magnesium sulfate and concentrated . vacuum distillation of the crude residue afforded the title compound as a colorless liquid ( 56 . 0 g , yield : 89 %): 1 h nmr ( 300 mhz , cdcl 3 , ppm ) δ : 7 . 15 - 7 . 13 ( d , 1h ), 6 . 78 - 6 . 76 ( d , 1h ), 2 . 57 - 2 . 52 ( t , 2h ), 1 . 59 - 1 . 54 ( m , 2h ), 1 . 29 - 1 . 27 ( m , 10h ), 0 . 90 - 0 . 86 ( t , 3h ). 2 - bromo - 3 - octylthiophene ( 10 g , 36 . 33 mmol ) was dissolved in thf ( 180 ml ) and the solution cooled to − 78 ° c . n - buli ( 23 . 8 ml , 38 . 15 mmol , 1 . 6 m buli in hexane ) was added dropwise over a period of 30 minutes . the reaction mixture was subsequently stirred at − 78 ° c . over a period of 2 h . 2 - isopropoxy - 4 , 4 , 5 , 5 - tetramethyl -[ 1 , 3 , 2 ] dioxaboralane ( 72 . 66 mmol , 14 . 8 ml ) was subsequently added to the reaction mixture over a period of 5 minutes . the reaction mixture was then allowed to warm to room temperature and stirred overnight . the reaction mixture was then quenched with a saturated aqueous nahco 3 solution ( 190 ml ). the reaction mixture was subsequently extracted with ethyl acetate ( 1800 ml ). the organic extract was washed with water , dried over sodium sulfate and subsequently concentrated to provide a crude residue which was purified by column chromatography using ethyl acetate : hexanes ( 1 : 20 ) as the eluant . the title compound was obtained as a colorless liquid ( 10 . 0 g , yield : 85 . 4 %): 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 47 ( d , 1h ), 7 . 02 ( d , 1h ), 2 . 89 ( t , 2h ), 1 . 57 ( m , 2h ), 1 . 32 ( br , 22h ), 0 . 92 ( t , 3h ). 1 , 3 - dibromo - 5 - octylthieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione ( 0 . 421 g , 1 mmol ) was dissolved in thf ( 10 ml ) in a 50 ml flask , followed by the addition of 2 - boranate 3 - octylthiophene ( 0 . 97 g , 3 mmol ), pd ( pph 3 ) 4 ( 11 mg , 10 %) and k 2 co 3 ( 5 ml , 2m aqueous solution ). the resulting reaction mixture was subsequently refluxed overnight . the reaction mixture was allowed to cool and was subsequently diluted with water . the reaction mixture was then extracted with dichloromethane ( 30 ml ), the organic phase dried over anhydrous magnesium sulfate and concentrated . purification by column chromatography using methylene dichloride : hexanes ( 20 : 1 ) as the eluant afforded the title compound as a green powder ( yield : 70 . 0 %). 1 , 3 - di ( 3 - octylthien - 2 - yl ) 5 - octylthieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione ( 2 mmol ) was dissolved in a mixture of acoh and chcl 3 ( 30 ml : 30 ml ) in a 100 ml flask placed in an ice bath . nbs ( 0 . 79 g , 4 . 4 mmol ) was subsequently added in several portions and the reaction mixture was stirred at room temperature over a period of 24 h . the solution was then slowly diluted with water and extracted with chloroform ( 200 ml ). the organic phase was dried and concentrated to afford a crude residue which was purified by column chromatography using methylene dichloride : hexanes ( 1 : 1 ) as the eluant . the title compound was obtained as a bright yellow powder ( yield : 90 %). thiophene - 3 - carboxylic acid ( 38 . 4 g , 0 . 3 mmol ) was dissolved in methylene chloride ( 60 ml ) in a 250 ml flask placed in an ice bath . oxalyl chloride ( 76 . 2 g , 0 . 6 mol , 53 ml ) was subsequently added . the reaction mixture was stirred overnight at room temperature resulting in a clear solution . the reaction mixture was subsequently concentrated to yield thiophene - 3 - carbonyl chloride as a colorless solid which was used without further purification . thiophene - 3 - carbonyl chloride was dissolved in methylene chloride ( 100 ml ) and added to a mixture of diethylamine ( 43 . 8 g , 0 . 6 mol ) and methylene chloride ( 100 ml ) placed in an ice bath . following the addition , the ice bath was removed and the resulting reaction mixture stirred at room temperature over a period of 4 h . the reaction mixture was washed several times with water and the organic layer dried over anhydrous magnesium sulfate and concentrated . vacuum distillation of the crude residue afforded the title compound as a light yellow oil ( yield : 91 %): gc - ms : 183 ; 1 h nmr ( 300 mhz , cdcl 3 , ppm ) δ : 7 . 36 ( d , 1h ), 7 . 22 - 7 . 19 ( m , 1h ), 7 . 08 - 7 . 06 ( m , 1h ). n , n - diethylthiophene - 3 - carboxamide ( 18 . 3 g , 0 . 1 mol ) was dissolved in thf ( 100 ml ) in a flame dried flask kept under an inert atmosphere . the reaction flak was placed in an ice bath followed by the dropwise addition of n - buli ( 40 . 0 ml , 2 . 5 m buli in hexane ) over a period of 30 minutes . the reaction mixture was then allowed to warm to room temperature and stirred over a period of 2 hours . the reaction mixture was subsequently slowly poured into ice water ( 250 ml ) and stirred for several hours . the resulting reaction mixture was filtered and the yellow precipitate washed successively with water , methanol ( 50 ml ) and hexanes ( 50 ml ). the title compound was obtained as a yellow powder ( yield : 75 %): gc - ms : 220 ; 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 69 - 7 . 68 ( d , 2h ), 7 . 65 - 7 . 64 ( d , 2h ); 1 h nmr ( 400 mhz , dmso - d 6 , ppm ) δ : 8 . 12 - 8 . 11 ( d , 2h ), 7 . 60 - 7 . 59 ( d , 2h ); 13 c nmr ( 100 mhz , cdcl 3 , ppm ) δ : 174 . 7 , 145 . 1 , 143 . 1 , 133 . 8 , 126 . 8 . a 250 ml flask was charged with 4 , 8 - dihydrobenzo [ 1 , 2 - b : 4 , 5 - b ′] dithiophen - 4 , 8 - dione ( 4 . 4 g , 20 mmol ), zinc powder ( 2 . 86 g , 44 mmol ) and water ( 60 ml ). naoh ( 12 g ) was subsequently added to the reaction mixture . the resulting reaction mixture was subsequently refluxed over a period of 2 hours . 1 - bromooctane ( 12 g , 60 mmol ) and tetrabutylammonium bromide ( 644 mg ) were subsequently added to the reaction mixture . the reaction mixture was then stirred overnight at 100 - 110 ° c . and subsequently slowly poured into cold water and extracted twice with diethyl ether . the organic layer was dried over anhydrous magnesium sulfate and concentrated . purification by column chromatography using methylene chloride : hexanes ( 1 : 8 ) as the eluant afforded the title compound as a white solid ( 7 . 8 g , yield : 87 . 0 %): gc - ms : m / z = 446 ; 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 48 - 7 . 47 ( d , 2h ), 7 . 37 - 7 . 36 ( d , 2h ), 4 . 28 - 4 . 26 ( m , 4h ), 1 . 91 - 1 . 84 ( m , 4h ), 1 . 60 - 1 . 52 ( m , 4h ), 1 . 36 - 1 . 31 ( m , 16 h ), 0 . 91 - 0 . 88 ( t , 6h ). the synthetic procedure is similar to that for the preparation of 4 , 8 - dioctyloxylbenzo [ 1 , 2 - b : 3 , 4 - b ] dithiophene . the title compound was obtained as a white solid ( 7 . 8 g , yield : 70 %): 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 48 - 7 . 47 ( d , 2h ), 7 . 37 - 7 . 35 ( d , 2h ), 4 . 29 - 4 . 26 ( m , 4h ), 1 . 88 - 1 . 86 ( m , 4h ), 1 . 58 - 1 . 56 ( m , 4h ), 1 . 40 - 1 . 27 ( m , 32h ), 0 . 90 - 0 . 87 ( t , 6h ), 0 . 45 ( s , 18h ). the synthetic procedure is similar to that for the preparation of 4 , 8 - dioctyloxylbenzo [ 1 , 2 - b : 3 , 4 - b ] dithiophene . the title compound was obtained as a colorless liquid ( 8 . 0 g , yield : 89 . 6 %): 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 54 - 7 . 53 ( d , 2h ), 7 . 40 - 7 . 39 ( d , 2 h ), 4 . 25 - 4 . 24 ( m , 4h ), 1 . 89 - 1 . 86 ( m , 2h ), 1 . 79 - 1 . 50 ( m , 6h ), 1 . 47 - 1 . 36 ( m , 10h ), 1 . 11 - 0 . 96 ( m , 12h ). the synthetic procedure is similar to that for the preparation of 4 , 8 - dioctyloxylbenzo [ 1 , 2 - b : 3 , 4 - b ] dithiophene . purification by column chromatography using hexanes followed by methylene chloride : hexanes ( 1 : 10 ) as the eluant afforded the title compound as a pale yellow liquid ( 9 . 0 g , yield : 87 . 0 %): 1 h nmr ( 300 mhz , cdcl 3 , ppm ) δ : 7 . 50 - 7 . 49 ( d , 2h ), 7 . 38 - 7 . 36 ( d , 2h ), 4 . 35 - 4 . 33 ( m , 4 h ), 1 . 97 ( m , 2h ), 1 . 83 ( m , 2h ), 1 . 61 ( m , 2h ), 1 . 39 - 1 . 18 ( m , 12h ), 1 . 01 - 0 . 99 ( d , 6h ), 0 . 91 - 0 . 89 ( d , 12 h ). 4 , 8 - dioctyloxylbenzo [ 1 , 2 - b : 3 , 4 - b ] dithiophene ( 0 . 62 g , 1 . 4 mmol ) was dissolved in thf ( 20 ml ) and the resulting solution cooled to − 78 ° c . under an argon atmosphere . n - buli ( 5 . 6 ml , 14 . 0 mmol , 2 . 5 m buli in hexane ) was added dropwise over a period of 15 minutes . the reaction mixture was subsequently stirred at − 78 ° c . over a period of 30 minutes . the reaction mixture was then allowed to warm to room temperature and stirred over a period of 2 hours resulting in the formation of a light green precipitate . the reaction mixture was subsequently cooled to − 78 ° c . followed by the addition of trimethyltin chloride ( 1 m in hexanes , 7 ml , and 7 mmol ). the precipitate disappeared and a clear solution was obtained . the reaction mixture was then allowed to warm to room temperature and stirred overnight . the reaction mixture was then quenched with a saturated aqueous nh 4 cl solution and extracted with hexanes . the organic extract was dried over anhydrous sodium sulfate and subsequently concentrated to provide a crude residue which was twice purified by recrystallization from isopropanol . the title compound was obtained as a colorless solid ( 0 . 87 g , yield : 80 . 0 %): 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 51 ( s , 2h ), 4 . 31 - 4 . 28 ( t , 4h ), 1 . 90 - 1 . 87 ( m , 4h ), 1 . 37 - 1 . 20 ( m , 20 h ), 0 . 91 - 0 . 88 ( t , 6h ), 0 . 45 ( s , 18 h ). 4 , 8 - didodecyloxylbenzo [ 1 , 2 - b : 3 , 4 - b ] dithiophene ( 0 . 78 g , 1 . 4 mmol ) was dissolved in thf ( 20 ml ) and the resulting solution cooled to − 78 ° c . under an argon atmosphere . n - buli ( 5 . 6 ml , 14 . 0 mmol , 2 . 5 m buli in hexane ) was added dropwise over a period of 15 minutes . the reaction mixture was subsequently stirred at − 78 ° c . over a period of 30 minutes . the reaction mixture was then allowed to warm to room temperature and stirred over a period of 1 hour resulting in the formation of a light green precipitate . the reaction mixture was subsequently cooled to − 78 ° c . followed by the addition of trimethyltin chloride ( 1 m in hexanes , 7 ml , and 7 mmol ). the precipitate disappeared and a clear solution was obtained . the reaction mixture was then allowed to warm to room temperature and stirred overnight . the reaction mixture was then quenched with a saturated aqueous nh 4 cl solution and extracted with hexanes . the organic extract was dried over anhydrous sodium sulfate and subsequently concentrated to provide a crude residue which was twice purified by recrystallization from isopropanol . the title compound was obtained as a colorless solid ( 1 . 04 g , yield : 87 . 0 %): 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 53 ( s , 2h ), 4 . 33 - 4 . 30 ( t , 4h ), 1 . 90 - 1 . 87 ( m , 4h ), 1 . 40 - 1 . 26 ( m , 36 h ), 0 . 90 - 0 . 87 ( t , 6h ), 0 . 45 ( s , 18 h ). 4 , 8 - di ( 2 - ethylhexyloxyl ) benzo [ 1 , 2 - b : 3 , 4 - b ] dithiophene ( 1 . 24 g , 2 . 8 mmol ) was dissolved in thf ( 40 ml ) and the resulting solution cooled to − 78 ° c . under an argon atmosphere . n - buli ( 5 . 6 ml , 14 . 0 mmol , 2 . 5 m buli in hexane ) was added dropwise over a period of 15 minutes . the reaction mixture was subsequently stirred at − 78 ° c . over a period of 30 minutes . the reaction mixture was then allowed to warm to room temperature and stirred over a period of 2 hours resulting in the formation of a light green precipitate . the reaction mixture was subsequently cooled to − 78 ° c . followed by the addition of trimethyltin chloride ( 1 m in hexanes , 14 ml , and 14 mmol ). the precipitate disappeared and a clear solution was obtained . the reaction mixture was then allowed to warm to room temperature and stirred overnight . the reaction mixture was then quenched with a saturated aqueous nh 4 cl solution and extracted with hexanes . the organic extract was dried over anhydrous sodium sulfate and subsequently concentrated to provide a crude residue which was twice purified by recrystallization from isopropanol . the title compound was obtained as a colorless solid ( 1 . 90 g , yield : 88 . 0 %): 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 56 ( s , 2h ), 4 . 24 - 4 . 23 ( t , 4h ), 1 . 90 - 1 . 87 ( m , 2h ), 1 . 8 - 1 . 41 ( m , 16 h ), 1 . 09 - 1 . 05 ( m , 12 h ), 0 . 49 ( s , 18h ). 4 , 8 -( 3 , 7 - dimethyloctyloxy ) benzo [ 1 , 2 - b : 3 , 4 - b ] dithiophene ( 1 . 76 g , 3 . 5 mmol ) was dissolved in thf ( 50 ml ) and the resulting solution cooled to − 78 ° c . under an argon atmosphere . n - buli ( 8 . 4 ml , 21 . 0 mmol , 2 . 5 m buli in hexane ) was added dropwise over a period of 15 minutes . the reaction mixture was subsequently stirred at − 78 ° c . over a period of 30 minutes . the reaction mixture was then allowed to warm to room temperature and stirred over a period of 2 hours resulting in the formation of a light green precipitate . the reaction mixture was subsequently cooled to − 78 ° c . followed by the addition of trimethyltin chloride ( 1 m in hexanes , 14 ml , and 14 mmol ). the precipitate disappeared and a clear solution was obtained . the reaction mixture was then allowed to warm to room temperature and stirred overnight . the reaction mixture was then quenched with a saturated aqueous nh 4 cl solution and extracted with hexanes . the organic extract was dried over anhydrous sodium sulfate and subsequently concentrated to provide a crude oily residue which was twice washed with isopropanol at − 78 ° c . the title compound was obtained as a colorless solid ( 2 . 10 g , yield : 69 %): 1 h nmr ( 300 mhz , cdcl 3 , ppm ) δ : 7 . 53 ( s , 2h ), 4 . 4 ( m , 4h ), 1 . 97 ( m , 2h ), 1 . 83 ( m , 2h ), 1 . 61 ( m , 2h ), 1 . 39 - 1 . 18 ( m , 12h ), 1 . 02 - 1 . 00 ( d , 6h ), 0 . 90 - 0 . 88 ( d , 12 h ), 0 . 46 ( s , 18h ). 2 , 2 ′- bithiophene ( 39 . 2 g , 0 . 236 mol ) was dissolved in a solvent mixture composed of acoh and chloroform ( 138 ml : 320 ml ). the reaction mixture was subsequently placed in an ice bath followed by the dropwise addition of br 2 ( 138 g , 44 . 4 ml ). the reaction mixture was then stirred at room temperature over a period of 5 h followed by overnight refluxing . the reaction mixture was allowed to cool and an aqueous koh solution ( 350 ml , 10 %) was subsequently added . the reaction mixture was subsequently extracted with chloroform ( 2 × 700 ml ). the combined organic extract was washed with water , dried over anhydrous magnesium sulfate and subsequently concentrated to provide a crude residue which was purified by recrystallization from ethanol . the title compound was obtained as a yellow solid ( 86 g , yield : 76 %); 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 05 ( s , 2h ). 3 , 3 ′- 5 , 5 ′- tetrabromo - 2 , 2 - bithiophene ( 9 . 64 g , 20 mmol ) was dissolved in anhydrous thf ( 200 ml ) and the resulting solution cooled to − 90 ° c . under an argon atmosphere . n - buli ( 16 ml , 40 . 0 mmol , 2 . 5 m buli in hexane ) was added dropwise over a period of 40 minutes . the reaction mixture was subsequently stirred at − 90 ° c . over a period of 60 minutes followed by the addition of chlorotrimethylsilane ( 5 . 4 g , 50 mmol , 6 . 3 ml ). the reaction mixture was stirred for an additional 30 minutes at − 90 ° c ., allowed to warm to room temperature and stirred overnight . the reaction mixture was subsequently poured into cold water and extracted three times with diethyl ether . the combined organic layers were dried over anhydrous magnesium sulfate and concentrated . purification by column chromatography using hexanes as the eluant afforded the title compound as a colorless solid ( 6 . 5 g , yield : 67 . 0 %): 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 16 ( s , 2h ), 0 . 34 ( s , 18 h ). 3 , 3 ′- dibromo - 5 , 5 ′- bis ( trimethylsilyl )- 2 , 2 ′- bithiophene ( 2 . 34 g , 5 mmol ) was dissolved in thf ( 40 ml ) in a 100 ml flask cooled to − 78 ° c . n - buli ( 4 . 21 ml , 10 . 53 mmol , 2 . 5 m buli in hexane ) was added dropwise over a period of 15 - 30 minutes . the reaction mixture was subsequently stirred at − 78 ° c . over a period of 60 minutes followed by the addition of dichlorodioctylsilane ( 2 . 08 ml , 6 mmol ). the reaction mixture was subsequently allowed to warm to room temperature and stirred overnight . the reaction mixture was then quenched with water and extracted three times with diethyl ether . the combined organic layers were dried over anhydrous magnesium sulfate and concentrated . purification by column chromatography using hexanes as the eluant afforded the title compound as a colorless oil ( 2 . 26 g , yield : 72 . 0 %): 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 14 ( s , 2h ), 1 . 24 ( m , 24 h ), 0 . 90 - 0 . 88 ( m , 10h ), 0 . 34 ( s , 18 h ). 4 , 4 ′- bis ( octyl )- 5 , 5 ′- bis ( trimethylsilyl )- dithieno [ 3 , 2 - b : 2 ′, 3 ′- d ] silole ( 1 . 19 g , 2 . 11 mmol ) was dissolved in thf ( 14 ml ). nbs ( 0 . 77 g , 4 . 33 mmol ) was subsequently added in several portions and the reaction mixture was stirred overnight . the reaction mixture was subsequently poured into cold water and extracted several times with diethyl ether . the combined organic layers were dried over anhydrous magnesium sulfate and concentrated . purification by column chromatography using hexanes as the eluant afforded the title compound ( yield : 84 . 0 %): 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 6 . 99 ( s , 2h ), 1 . 31 - 1 . 21 ( m , 24 h ), 0 . 89 - 0 . 85 ( t , 10h ). the synthetic procedure is similar to that for the preparation of 4 , 4 ′- bis ( octyl )- 5 , 5 ′- dibromo - dithieno [ 3 , 2 - b : 2 ′, 3 ′- d ] silole . 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 6 . 99 ( s , 2h ), 1 . 34 - 1 . 23 ( m , 16h ), 0 . 89 - 0 . 84 ( t , 10h ). 4 , 4 ′- bis ( octyl )- 5 , 5 ′- dibromo - dithieno [ 3 , 2 - b : 2 ′, 3 ′- d ] silole ( 1 . 2 g , 2 . 08 mmol ) was dissolved in anhydrous thf ( 20 ml ) and the resulting solution cooled to − 78 ° c . under an argon atmosphere . n - buli ( 2 . 6 ml , 6 . 5 mmol , 2 . 5 m buli in hexane ) was added dropwise over a period of 10 minutes . the reaction mixture was subsequently stirred at − 78 ° c . over a period of 30 minutes followed by the addition of trimethyltin chloride ( 1 m in hexanes , 7 ml , and 7 mmol ). the reaction mixture was then allowed to warm to room temperature and stirred overnight . the reaction mixture was subsequently poured into cold water and extracted several times with diethyl ether . the combined organic layers were dried over anhydrous magnesium sulfate and concentrated . the title compound was obtained as a sticky oil ( yield : 84 . 3 %): 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 09 ( s , 2h ), 1 . 62 - 1 . 24 ( m , 34 h ), 0 . 34 ( s , 18 h ). the synthetic procedure is similar to that for the preparation of 5 , 5 ′- bis ( trimethyltin )- 4 , 4 - bis ( octyl )- dithieno [ 3 , 2 - b : 2 ′, 3 ′- d ] silole . the title compound was obtained in 91 % yield : 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 09 ( s , 2h ), 1 . 62 - 1 . 24 ( m , 26 h ), 0 . 34 ( s , 18 h ). a mixture of 9 - heptanedecanone ( 12 g , 47 mmol ), ammonium acetate ( 36 . 32 g , 470 mmol ), nabh 3 cn ( 2 g , 31 mmol ) and methanol ( 140 ml ) was stirred at room temperature under an argon atmosphere over a period of 3 days . the reaction mixture was then acidified with excess concentrated hydrochloric acid until ph & lt ; 2 and concentrated . the residue was subsequently treated with an aqueous koh solution until ph & gt ; 10 and extracted with diethyl ether ( 3 × 300 ml ). the combined organic layers were dried over anhydrous magnesium sulfate and concentrated . vacuum distillation of the crude residue afforded the title compound as a colorless oil ( 9 . 4 g , yield : 82 %): 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 2 . 60 ( s , 1h ), 1 . 21 ( br , 28h ), 0 . 83 - 0 . 79 ( t , 6h ). 3 , 3 ′, 5 , 5 ′- tetrabromo - 2 , 2 - bithiophene ( 24 . 2 g , 0 . 05 mol ) was added portionwise over a period of 30 minutes to a refluxing dispersion of zinc powder ( 12 . 6 g , 0 . 2 mol ) in a solvent mixture comprising ethanol ( 250 ml ), water ( 50 ml ), glacial acetic acid ( 60 ml ) and hcl ( 5 ml ; 3m ). following overnight refluxing , the reaction mixture was allowed to cool to room temperature and was filtered . the solid was washed three times with ethanol . the combined filtrates were subsequently concentrated and the residue combined with water ( 125 ml ). the resulting mixture was subsequent extracted several times with diethyl ether . the combined organic layers were washed with water dried over anhydrous magnesium sulfate and concentrated . purification by column chromatography using hexanes as the eluant afforded the title compound as white crystals ( 10 . 9 g , yield : 67 . 0 %): 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 42 - 7 . 40 ( d , 2h ), 7 . 09 - 7 . 08 ( d , 2h ). to a solution of 3 , 3 - dibromo - 2 , 2 ′- bithiophene ( 4 . 92 g , 15 . 3 mmol ), t - buona ( 3 . 54 g , 36 . 8 mmol ), pd 2 dba 3 ( 0 . 35 g , 0 . 382 mmol ) and binap ( 0 . 95 g , 1 . 53 mmol ) in toluene ( 38 ml ) under an argon atmosphere was added 9 - octylnonylamine ( 4 g , 15 . 7 mmol ). the reaction mixture was subsequently stirred at 110 ° c . over a period of 7 hours . the reaction mixture was allowed to cool to room temperature followed by the addition of water . the organic layer was removed and the remaining aqueous phase extracted several times with diethyl ether . the combined organic layers were dried over anhydrous magnesium sulfate and concentrated . purification by column chromatography using hexanes as the eluant afforded the title compound as a light green solid ( 5 . 2 g , 81 % yield ): mp : 60 ° c . ; gc - ms : 417 . 5 ; 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 11 ( d , 2h ), 7 . 02 - 7 . 01 ( d , 2h ), 4 . 23 - 4 . 19 ( m , 1h ), 2 . 08 ( m , 2h ), 1 . 85 - 1 . 80 ( m , 2h ), 1 . 22 - 1 . 07 ( m , 24 h ), 0 . 86 - 0 . 82 ( t , 6 h ); 13 c nmr ( 100 mhz , cdcl 3 , ppm ) δ : 144 . 2 , 122 , 4 , 114 . 9 , 59 . 9 , 35 . 4 , 31 . 9 , 29 . 4 , 29 . 3 , 26 . 7 , 22 . 8 , 14 . 2 . n -( 1 - octylnonyl ) dithieno [ 3 , 2 - b : 2 ′, 3 ′- d ] pyrrole ( 0 . 834 g , 2 mmol ) was dissolved in anhydrous thf ( 40 ml ) and the resulting solution cooled to − 78 ° c . under an argon atmosphere . n - buli ( 4 . 0 ml , 10 . 0 mmol , 2 . 5 m buli in hexane ) was added dropwise over a period of 10 minutes . the reaction mixture was subsequently stirred at − 78 ° c . over a period of 60 minutes , allowed to warm to room temperature and stirred for an additional 2 hours . the reaction mixture was subsequently cooled to − 78 ° c . followed by the addition of trimethyltin chloride ( 1 m in hexanes , 10 ml , and 1 mmol ). the reaction mixture was then allowed to warm to room temperature and stirred overnight . the reaction mixture was then concentrated and the crude residue extracted with hexanes and filtered . following removal of the solvent , the title compound was obtained as a dark viscous green oil ( 1 . 13 g , yield : 82 %): gc - ms : 743 . 5 ; 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 05 ( s , 2h ), 4 . 37 ( m , 1h ), 2 . 1 ( m , 2h ), 1 . 90 ( m , 2h ), 1 . 32 - 1 . 23 ( m , 24 h ), 0 . 94 - 0 . 88 ( m , 6h ), 0 . 39 ( s , 18h ); 13 c nmr ( 100 mhz , cdcl 3 , ppm ) δ : 147 . 2 , 135 , 120 . 1 , 119 . 1 , 59 . 6 , 35 . 2 , 32 . 0 , 29 . 5 , 29 . 4 , 26 . 7 , 22 . 8 , 14 . 3 , − 8 . 1 . to a solution of 5 , 5 ′- bis ( trimethyltin )- 4 , 4 - bis ( octyl )- dithieno [ 3 , 2 - b : 2 ′, 3 ′- d ] silole ( 212 . 6 mg , 0 . 309 mmol ) and 1 , 3 - dibromo - 5 - octylthieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione ( 126 . 3 mg , 0 . 3 mmol ) in toluene ( 10 ml ) under an argon atmosphere was added pd 2 dba 3 ( 5 . 5 mg , 2 %) and p ( tolyl ) 3 ( 19 . 65 mg , 16 %). the reaction mixture was subsequently refluxed over a period of 48 h and end - capped using successively tributyltinthiophene and 2 - bromothiophene . the reaction mixture was subsequently allowed to cool to room temperature and the polymer precipitated using methanol ( 400 ml ). the polymer was then subjected to soxhlet extraction using methanol , hexanes and chloroform . the chloroform portion was concentrated and purified by precipitation from meoh . the polymer was obtained as a dark solid following drying under vacuum over a period of 12 hours ( yield : 65 %). to a solution of 1 , 3 - dibromo - 5 - octylthieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione ( 211 mg , 0 . 5 mmol ) and trans - 1 , 2 - bis ( tributylstannyl ) ethylene ( 303 mg , 0 . 5 mmol ) in toluene ( 10 ml ) in a 50 ml flask was added pd ( pph 3 ) 4 ( 15 mg ). the reaction mixture was subsequently refluxed over a period of 8 h and subsequently allowed to cool to room temperature . the polymer was precipitated using methanol ( 300 ml ) and subsequently subjected to soxhlet extraction using hexanes , acetone and chloroform . the chloroform portion was concentrated and purified by precipitation from meoh . the polymer was obtained as a dark - purple solid following drying under vacuum over a period of 12 hours ( yield : 15 %). to a solution of 1 , 3 - dibromo - 5 - octylthieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione ( 421 mg , 1 . 0 mmol ) and 2 , 5 - di ( trimethyl ) tin thiophene ( 409 . 7 mg , 1 mmol ) in toluene ( 15 ml ) in a 50 ml flask was added pd ( pph 3 ) 4 ( 30 mg ). the reaction mixture was subsequently refluxed over a period of 48 h and end - capped using successively 2 - bromothiophene and 2 - tributyltin thiophene . the reaction mixture was subsequently allowed to cool to room temperature and the polymer precipitated using methanol . the polymer was then subjected to soxhlet extraction using hexanes , acetone and chloroform . the chloroform portion was concentrated and purified by precipitation from meoh . the polymer was obtained as a dark - purple solid following drying under vacuum over a period of 12 hours ( yield : 26 %): m w = 1 . 9 k ; polydispersity = 1 . 18 . to a solution of 1 , 3 - di ( 2 - bromothien - 5 ′- yl )- 5 - octylthieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione ( 176 . 22 mg , 0 . 3 mmol ) and 2 , 7 -( bis ( 4 , 4 , 5 , 5 - tetramethyl - 1 , 3 , 2 - dioxaboralan - 2 - yl )- n - 9 - heptadecanylcarbazole ( 197 . 25 mg , 0 . 3 mmol ) in toluene ( 5 ml ) and water ( 1 . 2 ml ) was added pd 2 dba 3 ( 2 . 75 mg , 0 . 003 mmol ), sphos ( 5 mg ) and k 3 po 4 ( 509 . 4 mg , 2 . 4 mmol ). the reaction mixture was subsequently heated at 95 ° c . over a period of 24 h followed by the addition of bromobenzene ( 31 . 5 μl , 0 . 23 mmol ). following heating at 95 ° c . for an additional 3 hours , phenylboronic acid ( 36 . 6 mg , 0 . 25 mmol ) in toluene ( 2 ml ) was added . the reaction mixture was refluxed overnight to complete the end - capping reaction . the polymer was purified by precipitation using methanol / water ( 10 : 1 ) followed by filtration through a 0 . 45 μm nylon filter . the polymer was then subjected to soxhlet extraction using methanol , hexanes and chloroform . the chloroform portion was concentrated and purified by precipitation from meoh / h 2 o ( 10 : 1 , 300 ml ). the precipitate was filtration through a 0 . 45 μm nylon filter and the polymer isolated following drying under vacuum at 50 ° c . overnight ( 190 mg ; yield : 76 %): 1 h nmr ( 300 mhz , cdcl 3 , ppm ) δ : 8 . 15 ( br , 2h ), 7 . 59 - 7 . 10 ( br , 8h ), 4 . 67 ( br , 1h ), 3 . 76 ( br , 2h ), 2 . 37 - 1 . 95 ( br , 6h ), 1 . 33 - 1 . 25 ( br , 34h ), 0 . 91 - 0 . 82 ( br , 9h ); m w = 23 . 6 k ; polydispersity = 1 . 86 ( the 1 h nmr spectra and the temperature of degradation of polymer zp 30 are illustrated in fig8 and 9 ). a solution of 1 , 3 - di ( 2 - bromothien - 5 ′- yl )- 5 - octylthieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione ( 176 . 22 mg , 0 . 3 mmol ) and 5 , 5 ′- bis ( trimethyltin )- 4 , 4 - bis ( octyl )- dithieno [ 3 , 2 - b : 2 ′, 3 ′- d ] silole ( 234 mg , 0 . 315 mmol ) in toluene ( 10 ml ) in a 50 ml flask was flushed with argon over a period of 10 minutes . pd 2 dba 3 ( 5 . 5 mg , 2 mol %) and p ( tolyl ) 3 ( 14 . 6 mg , 16 %) were subsequently added to the reaction mixture which was subsequently heated at 95 ° c . over a period of 65 hours while under an argon atmosphere . 2 - bromothiophene ( 0 . 1 equiv ) was then added to the reaction mixture , the reaction mixture heated at 95 ° c . for an additional 2 hours and 2 - tributylstannyl thiophene ( 0 . 1 equiv ) added . the reaction mixture was then heated at 95 ° c . overnight to complete the end - capping reaction . the reaction mixture was subsequently allowed to cool to room temperature , the polymer precipitated using methanol / h 2 o ( 10 : 1 ) ( 300 ml ) and filtered through a 0 . 45 μm nylon filter . the polymer was then subjected to soxhlet extraction using methanol and hexanes . the polymer was taken - up in chloroform , the chloroform solution concentrated and the polymer precipitated using meoh / h 2 o ( 10 : 1 , 300 ml ). the precipitate was filtered through a 0 . 45 μm nylon filter and the polymer isolated as a purple solid following drying under vacuum at 50 ° c . over a period of 12 hours ( 100 mg ; yield : 41 %); m w = 5 . 2 k ; polydispersity = 2 . 08 . a solution of 1 , 3 - di ( 2 - bromothien - 5 ′- yl )- 5 - octylthieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione ( 176 . 28 mg , 0 . 3 mmol ) and 2 , 6 - bis ( trimethyltin )- n -( 1 - octylnonyl ) dithieno [ 3 , 2 - b : 2 ′, 3 ′- d ] pyrrole ( 223 mg , 0 . 3 mmol ) in toluene ( 10 ml ) in a 50 ml flask was flushed with argon over a period of 10 minutes . pd 2 dba 3 ( 5 . 5 mg , 2 mol %) and p ( tolyl ) 3 ( 19 . 6 mg , 16 %) were subsequently added to the reaction mixture which was subsequently heated at 95 ° c . over a period of 16 hours while under an argon atmosphere . 2 - bromothiophene ( 0 . 1 equiv ) was then added to the reaction mixture , the reaction mixture heated at 95 ° c . for an additional 2 hours and 2 - tributylstannyl thiophene ( 0 . 1 equiv ) added . the reaction mixture was then heated at 95 ° c . overnight to complete the end - capping reaction . the reaction mixture was subsequently allowed to cool to room temperature , the polymer precipitated using methanol / h 2 o ( 10 : 1 ) ( 300 ml ) and filtered through a 0 . 45 μm nylon filter . the polymer was then subjected to soxhlet extraction using methanol and hexanes . the polymer was taken - up in chloroform , the chloroform solution concentrated and the polymer precipitated using meoh / h 2 o ( 10 : 1 , 300 ml ). the precipitate was filtered through a 0 . 45 μm nylon filter and the polymer isolated as a dark blue solid following drying under vacuum at 50 ° c . over a period of 12 hours ( 177 mg ; yield : 75 %); m w = 36 . 4 k ; polydispersity = 1 . 83 . a solution of 1 , 3 - dibromo - 5 - octylthieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione ( 84 . 2 mg , 0 . 2 mmol ) and 2 , 6 - bis ( trimethyltin )- 4 , 8 - dioctyloxylbenzo [ 1 , 2 - b : 3 , 4 - b ] dithiophene ( 154 . 4 mg , 0 . 2 mmol ) in toluene ( 8 ml ) in a 25 ml flask was flushed with argon over a period of 10 minutes . pd 2 dba 3 ( 3 . 66 mg , 2 mol %) and p ( tolyl ) 3 ( 6 . 55 mg , 8 %) were subsequently added to the reaction mixture which was subsequently heated at 95 - 100 ° c . over a period of 24 hours while under an argon atmosphere . 2 - bromothiophene ( 0 . 1 equiv ) was then added to the reaction mixture , the reaction mixture heated at 95 - 100 ° c . for an additional 2 hours and 2 - tributylstannyl thiophene ( 0 . 1 equiv ) added . the reaction was then heated at 95 - 100 ° c . overnight to complete the end - capping reaction . the reaction mixture was subsequently allowed to cool to room temperature and the polymer precipitated using methanol / h 2 o ( 10 : 1 ) ( 300 ml ) and filtered through a 0 . 45 vim nylon filter . the polymer was then subjected to soxhlet extraction using methanol and hexanes . the polymer was taken - up in chloroform , the chloroform solution concentrated and the polymer precipitated using meoh / h 2 o ( 10 : 1 , 300 ml ). the precipitate was filtered through a 0 . 45 vim nylon filter and the polymer isolated as a dark purple solid following drying under vacuum at 50 ° c . over a period of 12 hours ( 60 mg ; yield : 43 %). a solution of 1 , 3 - dibromo - 5 - octylthieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione ( 126 . 3 mg , 0 . 3 mmol ), 2 , 7 -( bis ( 4 , 4 , 5 , 5 - tetramethyl - 1 , 3 , 2 - dioxaboralan - 2 - yl )- n - 9 - heptadecanylcarbazole ( 197 . 25 mg , 0 . 3 mmol ) in toluene ( 3 ml ) and water ( 1 . 2 ml ) was added pd 2 dba 3 ( 2 . 3 mg , 0 . 0025 mmol ), sphos ( 4 . 1 mg ) and k 3 po 4 ( 509 . 4 mg , 2 . 4 mmol ). the reaction mixture was subsequently heated at 95 ° c . over a period of 72 h followed by the addition of bromobenzene ( 31 . 5 μl , 0 . 23 mmol ). following heating at 95 ° c . for an additional 3 hours , phenylboronic acid ( 36 . 6 mg , 0 . 25 mmol ) in toluene ( 2 ml ) was added . the reaction mixture was refluxed overnight to complete the end - capping reaction . the polymer was purified by precipitation using methanol / water ( 10 : 1 ) followed by filtration through a 0 . 45 μm nylon filter . the polymer was then subjected to soxhlet extraction using methanol , hexanes and chloroform . the chloroform portion was concentrated and purified by precipitation from meoh / h 2 o ( 10 : 1 , 300 ml ). the precipitate was filtration through a 0 . 45 μm nylon filter and the polymer isolated as a red - brown solid following drying under vacuum at 50 ° c . overnight ( 110 mg ; yield : 55 %): m w = 4 k ; polydispersity = 1 . 4 . a solution of 1 , 3 - dibromo - 5 - octylthieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione ( 126 . 3 mg , 0 . 3 mmol ) and 2 , 6 - bis ( trimethyltin )- 4 , 8 - dioctyloxylbenzo [ 1 , 2 - b : 3 , 4 - b ] dithiophene ( 265 . 35 mg , 0 . 3 mmol ) in toluene ( 8 ml ) in a 50 ml flask was flushed with argon over a period of 10 minutes . pd 2 dba 3 ( 5 . 5 mg , 2 mol %) and p ( tolyl ) 3 ( 9 . 83 mg , 8 %) were subsequently added to the reaction mixture which was subsequently heated at 95 - 100 ° c . over a period of 24 hours while under an argon atmosphere . 2 - bromothiophene ( 0 . 1 equiv ) was then added to the reaction mixture , the reaction mixture heated at 95 - 100 ° c . for an additional 2 hours and 2 - tributylstannyl thiophene ( 0 . 1 equiv ) added . the reaction was then heated at 95 - 100 ° c . overnight to complete the end - capping reaction . the reaction mixture was subsequently allowed to cool to room temperature and the polymer precipitated using methanol / h 2 o ( 10 : 1 ) ( 300 ml ) and filtered through a 0 . 45 μm nylon filter . the polymer was then subjected to soxhlet extraction using methanol and hexanes . the polymer was taken - up in chloroform , the chloroform solution concentrated and the polymer precipitated using meoh / h 2 o ( 10 : 1 , 300 ml ). the precipitate was filtered through a 0 . 45 μm nylon filter and the polymer isolated as a dark purple solid following drying under vacuum at 50 ° c . over a period of 12 hours ( 150 mg ; yield : 72 %): m w = 10 . 6 k ; polydispersity = 2 . 21 . a solution of 1 , 3 - dibromo - 5 - octylthieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione ( 126 . 3 mg , 0 . 3 mmol ) and 2 , 6 - bis ( trimethyltin )- n -( 1 - octylnonyl ) dithieno [ 3 , 2 - b : 2 ′, 3 ′- d ] pyrrole ( 223 mg , 0 . 305 mmol ) in toluene ( 7 . 5 ml ) in a 50 ml flask was flushed with argon over a period of 10 minutes . pd 2 dba 3 ( 5 . 5 mg , 2 mol %) and p ( tolyl ) 3 ( 19 . 6 mg , 16 %) were subsequently added to the reaction mixture which was subsequently refluxed over a period of 24 hours while under an argon atmosphere . 2 - bromothiophene ( 0 . 1 equiv ) was then added to the reaction mixture , the reaction mixture refluxed for an additional 2 hours and 2 - tributylstannyl thiophene ( 0 . 1 equiv ) added . the reaction was then refluxed overnight to complete the end - capping reaction . the reaction mixture was subsequently allowed to cool to room temperature and the polymer precipitated using methanol / h 2 o ( 10 : 1 ) ( 300 ml ) and filtered through a 0 . 45 μm nylon filter . the polymer was then subjected to soxhlet extraction using methanol and hexanes . the polymer was taken - up in chloroform , the chloroform solution concentrated and the polymer precipitated using meoh / h 2 o ( 10 : 1 , 300 ml ). the precipitate was filtered through a 0 . 45 μm nylon filter and the polymer isolated as a dark blue solid following drying under vacuum at 50 ° c . over a period of 12 hours ( 180 mg ; yield : 89 %): m w = 17 . 1k ; polydispersity = 2 . 16 . a solution of 1 , 3 - dibromo - 5 - octylthieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione ( 210 . 5 mg , 0 . 5 mmol ) and 2 , 6 - bis ( trimethyltin )- 4 , 8 - dihexylethylbenzo [ 1 , 2 - b : 3 , 4 - b ] dithiophene ( 386 mg , 0 . 5 mmol ) in toluene ( 20 ml ) in a 50 ml flask was flushed with argon over a period of 10 minutes . pd 2 dba 3 ( 9 . 2 mg , 2 mol %) and p ( tolyl ) 3 ( 32 . 72 mg , 16 %) were subsequently added to the reaction mixture which was subsequently refluxed over a period of 24 hours while under an argon atmosphere . 2 - bromothiophene ( 0 . 1 equiv ) was then added to the reaction mixture , the reaction mixture refluxed for an additional 2 hours and 2 - tributylstannyl thiophene ( 0 . 1 equiv ) added . the reaction was then refluxed overnight to complete the end - capping reaction . the reaction mixture was subsequently allowed to cool to room temperature and the polymer precipitated using methanol / h 2 o ( 10 : 1 ) ( 300 ml ) and filtered through a 0 . 45 μm nylon filter . the polymer was then subjected to soxhlet extraction using methanol and hexanes . the polymer was taken - up in chloroform , the chloroform solution concentrated and the polymer precipitated using meoh / h 2 o ( 10 : 1 , 400 ml ). the precipitate was filtered through a 0 . 45 μm nylon filter and the polymer isolated as a dark purple solid following drying under vacuum at 50 ° c . over a period of 12 hours ( 340 mg ; yield : 98 %): 1 h nmr ( 300 mhz , cdcl 3 , ppm ) δ : 8 . 52 ( br , 2h ), 4 . 65 - 3 . 66 ( br , 4h ), 3 . 58 ( bs , 2h ), 1 . 38 - 1 . 25 ( br , 30h ), 0 . 93 ( br , 15h ). a solution of 1 , 3 - di ( 2 - bromothien - 5 ′- yl )- 5 - octylthieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione ( 58 . 4 mg , 0 . 1 mmol ) and 2 , 6 - bis ( trimethyltin )- 4 , 8 - dihexylethylbenzo [ 1 , 2 - b : 3 , 4 - b ] dithiophene ( 77 . 2 mg , 0 . 1 mmol ) in toluene ( 5 ml ) in a 25 ml flask was flushed with argon over a period of 10 minutes . pd 2 dba 3 ( 1 . 83 mg , 2 mol %) and p ( tolyl ) 3 ( 6 . 5 mg , 16 %) were added to the reaction mixture which was subsequently heated to 95 ° c . and stirred over a period of 16 hours while under an argon atmosphere . 2 - bromothiophene ( 0 . 1 equiv ) was then added to the reaction mixture , the reaction mixture heated at 95 ° c . for an additional 2 hours and 2 - tributylstannyl thiophene ( 0 . 1 equiv ) added . the reaction mixture was then continued to be heated at 95 ° c . overnight to complete the end - capping reaction . the reaction mixture was subsequently allowed to cool to room temperature and the polymer precipitated using methanol / h 2 o ( 10 : 1 ) ( 300 ml ) and filtered through a 0 . 45 μm nylon filter . the polymer was then subjected to soxhlet extraction using methanol and hexanes . the polymer was taken - up in chloroform , the chloroform solution concentrated and the polymer precipitated using meoh / h 2 o ( 10 : 1 , 300 ml ). the precipitate was filtered through a 0 . 45 μm nylon filter and the polymer isolated as a dark blue solid following drying under vacuum at 50 ° c . over a period of 12 hours ( 21 mg ; yield : 23 %). a solution of 1 , 3 - dibromo - 5 - hexylethylthieno [ 3 , 4 - c ] pyrrole - 4 , 6 - dione ( 168 . 4 mg , 0 . 4 mmol ) and 2 , 6 - bis ( trimethyltin )- 4 , 8 - dihexylethylbenzo [ 1 , 2 - b : 3 , 4 - b ] dithiophene ( 308 . 8 mg , 0 . 4 mmol ) in toluene ( 15 ml ) in a 50 ml flask was flushed with argon over a period of 10 minutes . pd 2 dba 3 ( 7 . 3 mg , 2 mol %) and p ( tolyl ) 3 ( 26 . 2 mg , 16 %) were added to the reaction mixture which was subsequently refluxed and stirred over a period of 24 hours while under an argon atmosphere . 2 - tributylstannyl thiophene ( 39 . 5 μl ) was then added to the reaction mixture , the reaction mixture refluxed for an additional 2 hours and 2 - bromothiophene ( 12 . 5 μl ) added . the reaction mixture was then continued to be refluxed overnight to complete the end - capping reaction . the reaction mixture was subsequently allowed to cool to room temperature and the polymer precipitated using methanol / h 2 o ( 10 : 1 ) ( 300 ml ) and filtered through a 0 . 45 μm nylon filter . the polymer was then subjected to soxhlet extraction using methanol and hexanes . the polymer was taken - up in chloroform , the chloroform solution concentrated and the polymer precipitated using meoh / h 2 o ( 10 : 1 , 400 ml ). the precipitate was filtered through a 0 . 45 μm nylon filter and the polymer isolated as a dark purple solid following drying under vacuum at 50 ° c . over a period of 12 hours ( 233 mg ; yield : 84 %): 1 h nmr ( 300 mhz , cdcl 3 , ppm ) δ : 8 . 52 ( br , 2h ), 4 . 65 - 3 . 66 ( br , 4h ), 3 . 58 ( bs , 2h ), 1 . 38 - 1 . 25 ( br , 27h ), 0 . 93 ( br , 18h ) ( the 1 h nmr spectra of polymer zp 51 is illustrated in fig1 ). to a solution of 2 - bromo - 3 - ethylthiophene ( 5 . 00 g , 26 . 17 mmol ) in dry tetrahydrofuran ( 50 ml ) at − 78 ° c . was added dropwise n - butyllithium ( 2 . 5m in hexane ) ( 27 . 60 mmol , 11 . 0 ml ). the solution was stirred at − 78 ° c . for 2 h . then , trimethyltin chloride ( 39 . 40 mmol , 40 . 0 ml ) was added at once to the reaction mixture . the cooling bath was removed and the reaction was warmed to room temperature overnight . the reaction mixture was then poured into hexanes . the organic phase was washed with water then brine . the solvent was removed under reduced pressure and the crude product ( brownish oil ) was purified by distillation under high vacuum to afford 4 . 57 g of the title product as a colorless oil ( y = 63 %) ( b . p . 73 - 75 ° c ./ 0 . 35 mmhg ). 1 h nmr ( 300 mhz , cdcl 3 , ppm ) δ : 7 . 55 ( d , 1h , j = 4 . 6 hz ); 7 . 13 ( d , 1h , j = 4 . 7 hz ); 2 . 68 ( q , 2h , j = 7 . 7 hz ); 1 . 24 ( t , 3h , j = 7 . 5 hz ); 0 . 39 ( s , 9h ). compound 4 ( 2 . 10 g , 4 . 96 mmol ) was dissolved into dry tetrahydrofuran ( 200 ml ). 2 -( tributylstannyl ) thiophene ( 15 . 00 mmol , 4 . 76 ml ) and bis ( triphenylphosphine ) palladium ( ii ) dichloride ( 210 mg , 6 %) were added to the reaction mixture . the solution was refluxed for 24 h then cooled down and poured into water . the mixture was extracted twice with dichloromethane . the organic phases were combined and washed with brine and dried over anhydrous magnesium sulphate . the solvent was removed under reduce pressure and the crude product was purified by column chromatography using dichloromethane / hexanes as the eluent ( ratio 1 : 1 ) to afford 1 . 60 g of the title product as a green powder ( y = 75 %). 1 h nmr ( 400 mhz , d 8 - thf , ppm ) δ : 8 . 33 ( d , 2h ); 7 . 78 ( d , 2h ); 7 . 34 ( t , 2h , j = 4 . 2 hz ); 3 . 83 ( t , 2h , j = 7 . 1 hz ); 1 . 89 ( m , 2h ); 1 . 53 - 1 . 47 ( m , 10h ); 1 . 05 ( t , 3h , j = 7 . 2 hz ); 13 c nmr ( 100 mhz , d 8 - thf ) δ : 162 . 08 ; 135 . 71 ; 132 . 57 ; 130 . 09 ; 129 . 12 ; 128 . 94 ; 128 . 42 ; 38 . 14 ; 32 . 00 ; 29 . 36 ; 28 . 48 ; 26 . 99 ; 22 . 73 ; 13 . 62 . * one peak is missing due to the deuterated solvent . the title compound was synthesized as described for 11 using 5 ( 2 . 10 g , 4 . 96 mmol ), dry thf ( 100 ml ), 2 -( tributylstannyl ) thiophene ( 15 . 00 mmol , 4 . 76 ml ) and bis ( triphenylphosphine ) palladium ( ii ) dichloride ( 210 mg , 6 %) to afford 1 . 90 g of the title product as a green powder ( y = 89 %). 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 8 . 03 ( d , 2h , j = 3 . 1 hz ); 7 . 44 ( d , 2h , j = 4 . 6 hz ); 7 . 13 ( t , 2h , j = 4 . 0 hz ); 3 . 58 ( d , 2h , j = 7 . 3 hz ); 1 . 87 - 1 . 84 ( m , 1h ); 1 . 46 - 1 . 26 ( m , 8h ); 0 . 94 - 0 . 88 ( m , 6h ); 13 c nmr ( 100 mhz , cdcl 3 , ppm ) δ : 163 . 17 ; 136 . 72 ; 132 . 68 ; 130 . 15 ; 128 . 87 ; 128 . 69 ; 128 . 65 ; 42 . 75 ; 38 . 49 ; 30 . 83 ; 28 . 84 ; 24 . 14 ; 23 . 28 ; 14 . 33 ; 10 . 70 . the title compound was synthesized as described for 11 using 6 ( 1 . 00 g , 2 . 09 mmol ), dry thf ( 50 ml ), 2 -( tributylstannyl ) thiophene ( 4 . 18 mmol , 1 . 45 ml ) and bis ( triphenylphosphine ) palladium ( ii ) dichloride ( 73 mg , 6 %) to afford 0 . 82 g of the title product as a yellow green powder ( y = 82 %). 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 8 . 01 ( d , 2h , j = 3 . 0 hz ); 7 . 45 ( d , 2h , j = 0 . 6 hz ); 7 . 13 ( t , 2h , j = 1 . 0 hz ); 3 . 66 ( t , 2h , j = 7 . 3 hz ); 1 . 70 - 1 . 65 ( m , 2h ); 1 . 37 - 1 . 25 ( m , 18h ); 0 . 95 ( t , 3h , j = 7 . 3 hz ); 13 c nmr ( 100 mhz , cdcl 3 , ppm ) δ : 162 . 87 ; 136 . 73 ; 132 . 68 ; 130 . 11 ; 128 . 89 ; 128 . 67 ; 128 . 63 ; 38 . 83 ; 32 . 16 ; 29 . 91 ; 29 . 88 ; 29 . 83 ; 29 . 74 ; 29 . 60 ; 29 . 48 ; 28 . 73 ; 27 . 20 ; 22 . 94 ; 14 . 39 . the title compound was synthesized as described for 11 using 4 ( 1 . 26 g , 2 . 98 mmol ), dry thf ( 100 ml ), 2 -( trimethyltin - 3 - octylthiophene ) ( 7 . 45 mmol , 3 . 58 g ) and bis ( triphenylphosphine ) palladium ( ii ) dichloride ( 210 mg , 6 %). the crude product was purified by column chromatography using dichloromethane / hexanes as the eluent ( ratio 3 : 2 ) to afford 1 . 52 g of the title product as a sticky oil ( y = 79 %). 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 42 ( d , 2h , j = 5 . 2 hz ); 7 . 02 ( d , 2h , j = 5 . 2 hz ); 3 . 63 ( t , 2h , j = 7 . 2 hz ); 2 . 80 ( t , 4h , j = 7 . 9 hz ); 1 . 66 - 1 . 63 ( m , 6h ); 1 . 30 - 1 . 25 ( m , 30h ); 0 . 88 ( t , 9h , j = 6 . 4 hz ); 13 c nmr ( 100 mhz , cdcl 3 , ppm ) δ : 162 . 55 ; 144 . 55 ; 137 . 25 ; 130 . 83 ; 130 . 06 ; 127 . 83 ; 125 . 27 ; 38 . 69 ; 32 . 11 ; 32 . 04 ; 30 . 77 ; 29 . 89 ; 29 . 77 ; 29 . 64 ; 29 . 50 ; 29 . 43 ; 29 . 40 ; 28 . 69 ; 27 . 19 ; 22 . 90 ; 22 . 87 ; 14 . 34 ; 14 . 33 . the title compound was synthesized as described for 11 using 4 ( 0 . 97 g ; 22 . 90 mmol ), dry thf ( 60 ml ), 2 -( trimethyltin )- 3 - ethylthiophene ( 1 . 89 g ; 69 . 00 mmol ) and bis ( triphenylphosphine ) palladium ( ii ) dichloride ( 96 mg , 6 %) to afford 0 . 75 g of the title product as a sticky orange oil ( y = 68 %). 1 h nmr ( 300 mhz , cdcl 3 , ppm ) δ : 7 . 42 ( d , 2h , j = 5 . 2 hz ); 7 . 05 ( d , 2h , j = 5 . 2 hz ); 3 . 06 ( t , 2h , j = 7 . 2 hz ); 2 . 82 ( q , 4h , j = 7 . 5 hz ); 1 . 67 - 1 . 59 ( m , 2h ); 1 . 28 ( m , 16h ); 0 . 86 ( t , 3h , j = 6 . 3 hz ); 13 c nmr ( 75 mhz , cdcl 3 , ppm ) δ : 162 . 33 ; 145 . 55 ; 137 . 04 ; 130 . 71 ; 129 . 35 ; 127 . 76 ; 124 . 63 ; 38 . 47 ; 31 . 80 ; 29 . 18 ( 2c ); 28 . 48 ; 26 . 95 ; 22 . 91 ; 22 . 65 ; 14 . 79 ; 14 . 10 . the title compound was synthesized as described for 11 using 4 ( 1 . 00 g , 2 . 36 mmol ), dry thf ( 50 ml ), 2 -( trimethyltin )- 4 - octylthiophene ( 1 . 87 g ; 5 . 20 mmol ) and bis ( triphenylphosphine ) palladium ( ii ) dichloride ( 9 . 9 mg , 6 %) to afford 0 . 55 g of the title product as a sticky orange oil ( y = 36 %). 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 87 ( s , 2h ); 7 . 02 ( s , 2h ); 3 . 65 ( t , 2h , j = 7 . 4 hz ); 2 . 26 ( t , 4h , j = 7 . 6 hz ); 1 . 67 - 1 . 61 ( m , 6h ); 1 . 33 - 1 . 29 ( m , 30h ); 0 . 89 ( t , 9h , j = 6 . 5 hz ); 13 c nmr ( 100 mhz , cdcl 3 , ppm ) δ : 162 . 94 ; 145 . 18 ; 137 . 02 ; 132 . 38 ; 131 . 32 ; 128 . 28 ; 123 . 77 ; 38 . 83 ; 32 . 13 ; 30 . 70 ; 29 . 65 ; 29 . 52 ; 29 . 49 ; 29 . 43 ; 28 . 80 ; 27 . 24 ; 22 . 93 ; 14 . 37 . * some peaks are missing due to overlapping . the title compound was synthesized as described for 11 using 6 ( 0 . 95 g , 1 . 98 mmol ), dry thf ( 46 ml ), 2 -( trimethyltin )- 3 - octylthiophene ) ( 4 . 35 mmol , 1 . 56 g ) and bis ( triphenylphosphine ) palladium ( ii ) dichloride ( 8 . 3 mg , 6 %) were added to the solution . the crude product was purified by column chromatography using dichloromethane / hexanes as the eluent ( ratio 2 : 3 ) to afford 0 . 96 g of the title product as a yellow solid ( y = 68 %). 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 46 ( d , 2h , j = 5 . 1 hz ); 7 . 04 ( d , 2h , j = 5 . 2 hz ); 3 . 64 ( t , 2h , j = 7 . 2 hz ); 2 . 86 ( t , 4h , j = 7 . 7 hz ); 1 . 70 - 1 . 59 ( m , 6h ); 1 . 31 - 1 . 25 ( m , 38h ); 0 . 86 ( t , 9h , j = 3 . 9 hz ); 13 c nmr ( 100 mhz , cdcl 3 , ppm ) δ : 167 . 24 ; 145 . 19 ; 131 . 58 ; 130 . 30 ; 130 . 04 ; 128 . 31 ; 112 . 99 ; 38 . 64 ; 31 . 90 ; 31 . 79 ; 30 . 56 ; 29 . 50 ; 29 . 40 ; 29 . 27 ; 29 . 17 ; 26 . 95 ; 22 . 68 ; 22 . 62 ; 14 . 10 ; 14 . 07 . * some peaks are missing due to overlapping the title compound was synthesized as described for 11 using 6 ( 0 . 91 g , 1 . 90 mmol ), dry thf ( 45 ml ), 2 -( trimethyltin )- 4 - octylthiophene ( 1 . 5 g , 4 . 17 mmol ) and bis ( triphenylphosphine ) palladium ( ii ) dichloride ( 8 . 0 mg , 6 % mol ). the crude product was purified by column chromatography using dichloromethane / hexanes as the eluent ( ratio 2 : 3 ) to afford 0 . 73 g of the title product as a yellow wax ( y = 75 %). 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 87 ( s , 2h ); 7 . 01 ( s , 2h ); 3 . 65 ( t , 2h , j = 7 . 3 hz ); 2 . 62 ( t , 4h , j = 7 . 6 hz ); 1 . 65 - 1 . 61 ( m , 6h ); 1 . 33 - 1 . 25 ( m , 38h ); 0 . 88 ( t , 9h , j = 4 . 9 hz ); 13 c nmr ( 100 mhz , cdcl 3 , ppm ) δ : 162 . 91 ; 145 . 17 ; 136 . 99 ; 132 . 38 ; 131 . 31 ; 128 . 27 ; 123 . 74 ; 38 . 83 ; 32 . 17 ; 32 . 13 ; 30 . 70 ; 30 . 66 ; 29 . 89 ; 29 . 84 ; 29 . 77 ; 29 . 66 ; 29 . 60 ; 29 . 57 ; 29 . 53 ; 28 . 80 ; 27 . 25 ; 22 . 93 ; 14 . 37 . * some peaks are missing due to overlapping compound ii ( 0 . 86 g , 2 . 00 mmol ) was dissolved in a mixture of acetic acid and chloroform ( 60 ml ) ( ratio 1 / 1 ). the solution was cooled down to 0 ° c . and kept in the dark . n - bromosuccinimide ( 0 . 79 g , 4 . 43 mmol ) was added to the solution in several portions . the cooling bath was removed and the reaction was stirred at ambient temperature for 24 h . the reaction solution was poured into water and extracted several times with chloroform . the organic phases were combined , washed with brine and dried over anhydrous magnesium sulphate . the solvent was removed under reduced pressure and the crude product was purified by column chromatography using dichloromethane / hexanes as the eluent ( ratio 1 : 1 ) to afford 1 . 16 g of the title product as a bright yellow solid ( y = 99 %). 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 65 ( d , 2h , j = 4 hz ); 7 . 09 ( d , 2h , j = 4 hz ); 3 . 64 ( t , 2h , j = 6 . 9 hz ); 1 . 67 ( m , 2h ); 1 . 32 - 1 . 26 ( m , 10h ); 0 . 87 ( t , 3h , j = 5 . 4 hz ); 13 c nmr ( 100 mhz , cdcl 3 , ppm ) δ : 162 . 54 ; 135 . 32 ; 133 . 96 ; 131 . 37 ; 129 . 97 ; 128 . 83 ; 116 . 98 ; 38 . 93 ; 32 . 03 ; 29 . 41 ( 2c ); 28 . 69 ; 27 . 20 ; 22 . 87 ; 14 . 34 . the title compound was synthesized as described for 19 using 12 ( 1 . 29 g , 3 . 00 mmol ), a mixture of acetic acid and chloroform ( 60 ml ) ( ratio 1 / 1 ) at 0 ° c . and n - bromosuccinimide ( 1 . 20 g , 6 . 67 mmol ). the crude product was purified by gradient column chromatography using hexanes to dichloromethane / hexanes ( ratio 1 : 1 to 2 : 3 ) to afford 1 . 72 g of the title product as a bright yellow solid ( y = 98 %). 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 65 ( d , 2h , j = 4 . 0 hz ); 7 . 07 ( d , 2h , j = 4 . 0 hz ); 3 . 54 ( d , 2h , j = 7 . 3 hz ); 1 . 82 ( t , 1h , j = 6 . 0 hz ); 1 . 38 - 1 . 29 ( m , 8h ); 0 . 92 ( t , 6h , j = 2 . 9 hz ); 13 c nmr ( 100 mhz , cdcl 3 , ppm ) δ : 162 . 92 ; 135 . 37 ; 133 . 96 ; 131 . 38 ; 130 . 01 ; 128 . 79 ; 116 . 98 ; 42 . 87 ; 38 . 51 ; 30 . 83 ; 28 . 86 ; 28 . 83 ; 24 . 13 ; 23 . 28 ; 14 . 34 . the title compound was synthesized as described for 19 using 13 ( 0 . 80 g , 1 . 65 mmol ), a mixture of acetic acid and chloroform ( 40 ml ) ( ratio 1 / 1 ) at 0 ° c . and n - bromosuccinimide ( 0 . 65 g , 3 . 62 mmol ). the crude product was purified by column chromatography using dichloromethane / hexanes as the eluent ( ratio 1 : 1 ) to afford 0 . 80 g of the title product as a yellow solid ( y = 76 %). 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 65 ( d , 2h , j = 4 . 0 hz ); 7 . 08 ( d , 2h , j = 4 . 0 hz ); 3 . 64 ( t , 2h , j = 7 . 3 hz ); 1 . 66 ( m , 2h ); 1 . 32 - 1 . 25 ( m , 18h ); 0 . 87 ( t , 3h , j = 6 . 5 hz ); 13 c nmr ( 100 mhz , cdcl 3 , ppm ) δ : 162 . 63 ; 135 . 39 ; 133 . 96 ; 131 . 39 ; 129 . 99 ; 128 . 87 ; 116 . 97 ; 38 . 95 ; 32 . 16 ; 31 . 20 ; 29 . 87 ; 29 . 81 ; 29 . 72 ; 29 . 60 ; 29 . 45 ; 28 . 69 ; 27 . 18 ; 22 . 94 ; 14 . 28 . the title compound was synthesized as described for 19 using 14 ( 1 . 10 g , 1 . 72 mmol ), a mixture of acetic acid and chloroform ( 50 ml ) ( ratio 1 / 1 ) at 0 ° c . and n - bromosuccinimide ( 0 . 68 g , 3 . 76 mmol ). after the addition of nbs , the cooling bath was removed and the reaction was stirred at ambient temperature for 24 h . the solution was then heated up to 55 ° c . for 24 h . the reaction was carefully monitored by tlc . the reaction mixture was cooled down and poured into water . the mixture was extracted three times using chloroform . the chloroform parts were combined and washed with brine and dried over anhydrous magnesium sulphate . the crude product was purified by column chromatography using dichloromethane / hexanes as the eluent ( ratio 1 : 1 ) to afford 1 . 30 g of the title product as a yellow solid ( y = 82 %). 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 6 . 96 ( s , 2 h ); 3 . 60 ( t , 2h , j = 7 . 1 hz ); 2 . 75 - 2 . 71 ( t , 4h , j = 7 . 6 hz ); 1 . 64 - 1 . 60 ( m , 6 h ); 1 . 30 - 1 . 25 ( m , 30 h ); 0 . 88 - 0 . 84 ( t , 9h , j = 5 . 7 hz ); 13 c nmr ( 100 mhz , cdcl 3 , ppm ) δ : 162 . 26 ; 145 . 13 ; 135 . 63 ; 132 . 81 ; 130 . 94 ; 126 . 63 ; 115 . 69 ; 38 . 78 ; 32 . 11 ; 32 . 04 ; 30 . 57 ; 30 . 06 ; 29 . 73 ; 29 . 61 ; 29 . 49 ; 29 . 42 ( 2c ); 28 . 68 ; 27 . 19 ; 22 . 92 ; 22 . 89 ; 14 . 35 ; 14 . 32 . the title compound was synthesized as described for 22 using 15 ( 0 . 36 g , 0 . 75 mmol ), a mixture of acetic acid and chloroform ( 24 ml ) ( ratio 1 / 1 ) at 0 ° c . and n - bromosuccinimide ( 0 . 29 g , 1 . 65 mmol ) to afford 0 . 32 g of the title product as a highly viscous orange oil ( y = 66 %). 1 h nmr ( 300 mhz , cdcl 3 , ppm ) δ : 7 . 01 ( s , 2h ); 3 . 61 ( t , 2h , j = 7 . 4 hz ); 2 . 7 ( q , 4h , j = 7 . 5 hz ); 1 . 66 - 1 . 60 ( m , 2h ); 1 . 28 - 1 . 23 ( m , 16h ); 0 . 87 ( t , 3h , j = 6 . 2 hz ); 13 c nmr ( 75 mhz , cdcl 3 , ppm ) δ : 162 . 07 ; 146 . 13 ; 135 . 42 ; 132 . 19 ; 130 . 83 ; 126 . 08 ; 115 . 53 ; 38 . 58 ; 31 . 79 ; 29 . 17 ( 2c ); 28 . 45 ; 26 . 95 ; 23 . 09 ; 22 . 65 ; 14 . 61 ; 14 . 11 . the title compound was synthesized as described for 22 using 16 ( 0 . 55 g , 0 . 85 mmol ), a mixture of acetic acid and chloroform ( 20 ml ) ( ratio 1 / 1 ) at 0 ° c . and n - bromosuccinimide ( 0 . 29 g , 1 . 65 mmol ) to afford 0 . 52 g of the title product as a yellow solid ( y = 72 %). 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 7 . 60 ( s , 2h ); 3 . 61 ( t , 2h , j = 7 . 1 hz ); 2 . 54 ( t , 4h , j = 7 . 5 hz ); 1 . 66 - 1 . 60 ( m , 6h ); 1 . 33 - 1 . 28 ( m , 30h ); 0 . 87 ( t , 9h , j = 6 . 6 hz ); 13 c nmr ( 100 mhz , cdcl 3 , ppm ) δ : 162 . 61 ; 143 . 96 ; 135 . 62 ; 132 . 09 ; 130 . 47 ; 128 . 49 ; 113 . 76 ; 38 . 91 ; 32 . 13 ; 29 . 96 ; 29 . 89 ; 29 . 75 ; 29 . 61 ; 29 . 52 ; 29 . 46 ; 28 . 76 ; 27 . 25 ; 22 . 93 ; 14 . 38 . * some peaks are missing due to overlapping the title compound was synthesized as described for 22 using 17 ( 1 . 47 g , 2 . 07 mmol ), a mixture of acetic acid and chloroform ( 50 ml ) ( ratio 1 / 1 ) at 0 ° c . and n - bromosuccinimide ( 0 . 82 g , 4 . 55 mmol ) to afford 1 . 26 g of the title product as a yellow solid ( y = 70 %). 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 6 . 98 ( s , 2h ); 3 . 61 ( t , 2h , j = 7 . 2 hz ); 2 . 74 ( t , 4h , j = 7 . 8 hz ); 1 . 64 - 1 . 58 ( m , 6h ); 1 . 30 - 1 . 26 ( m , 38h ); 0 . 87 ( t , 9h , j = 6 . 4 hz ); 13 c nmr ( 100 mhz , cdcl 3 , ppm ) δ : 162 . 34 ; 145 . 17 ; 135 . 69 ; 132 . 84 ; 130 . 97 ; 126 . 55 ; 115 . 68 ; 38 . 81 ; 32 . 10 ; 32 . 03 ; 30 . 59 ; 30 . 03 ; 29 . 71 ; 29 . 60 ; 29 . 47 ; 29 . 42 ; 29 . 40 ; 28 . 67 ; 27 . 18 ; 22 . 90 ; 22 . 87 ; 14 . 35 . * some peaks are missing due to overlapping the title compound was synthesized as described for 22 using 18 ( 0 . 60 g , 0 . 85 mmol ), a mixture of acetic acid and chloroform ( 20 ml ) ( ratio 1 : 1 ) at 0 ° c . and n - bromosuccinimide ( 0 . 29 g , 1 . 65 mmol ) to afford 0 . 45 g of the title product as a yellow solid ( y = 65 %). 1 h nmr ( 400 mhz , cdcl 3 , ppm ) δ : 6 . 98 ( s , 2h ); 3 . 61 ( t , 2h , j = 7 . 2 hz ); 2 . 74 ( t , 4h , j = 7 . 8 hz ); 1 . 64 - 1 . 58 ( m , 6h ); 1 . 30 - 1 . 26 ( m , 38h ); 0 . 87 ( t , 9h , j = 6 . 4 hz ); 13 c nmr ( 100 mhz , cdcl 3 , ppm ) δ : 162 . 61 ; 143 . 95 ; 135 . 63 ; 132 . 09 ; 130 . 46 ; 128 . 50 ; 113 . 76 ; 38 . 92 ; 32 . 17 ; 32 . 13 ; 29 . 97 ; 29 . 89 ; 29 . 84 ; 29 . 77 ; 29 . 61 ; 29 . 52 ; 28 . 76 ; 27 . 25 ; 22 . 95 ; 22 . 94 ; 14 . 38 * some peaks are missing due to overlapping 2 , 6 - bis ( trimethyltin )- 4 , 8 - di ( 2 - ethylhexyloxyl )- benzo [ 1 , 2 - b : 3 , 4 - b ] dithiophene ( 27 ) ( 0 . 5 mmol ), compounds ( 4 - 6 ; 19 - 26 ) ( 0 . 5 mmol ), pd 2 ( dba ) 3 ( 2 mol %) and p ( o - tol ) 3 ( 8 mol %) were put in a round bottom flask ( 25 ml ). the system was then purged three times by vacuum / argon cycling . the solids were dissolved in 16 ml of dry and oxygen free toluene . the temperature was increased from room temperature to 110 ° c . using an oil bath equipped with a temperature controller . after 24 to 36 h of polymerization time , 100 μl of bromobenzene was added to the viscous reaction mixture as end - capping agent . after an additional hour of reaction , 100 μl of trimethyltin phenyl was added to complete the end capping procedure . after an additional hour of reaction , the whole mixture was cooled to room temperature and poured in 500 ml of cold methanol . the precipitate was filtered . soxhlet extraction with acetone followed by hexane removed catalyst residues and low molecular weight material . polymers were then extracted with chloroform . the solvent was reduced to about 30 ml and the mixture was poured into cold methanol . polymers were recovered by filtration . typical yields from 80 to 95 % were obtained . it is to be understood that the specification is not limited in its application to the details of construction and parts as described hereinabove . the specification is capable of other embodiments and of being practiced in various ways . it is also understood that the phraseology or terminology used herein is for the purpose of description and not limitation . hence , although the present invention has been described hereinabove by way of illustrative embodiments thereof , it can be modified , without departing from the spirit , scope and nature of the subject disclosure as defined in the appended claims . 1 . g . li , v . shrotriya , j . huang , y . yao , t . moriarty , k . emery , y . yang , nature mater . 2005 , 4 , 864 . 2 . j . y . kim , s . h . kim , h . h . lee , k . lee , w . ma , x . gong , a . j . heeger , adv . mater . 2006 , 18 , 572 . 3 . k . kim , j . liu , m . a . g . namboothiry , d . l . carroll , appl . phys . lett . 2007 , 90 , 163511 . 4 . j . peet , j . y . kim , n . e . coates , w . l . ma , d . moses , a . j . heeger , g . c . bazan , nature mater . 2007 , 6 , 497 . 5 . s . h . park , a . roy , s . beaupré , s . cho , n . coates , j . s . moon , d . moses , m . leclerc , k . lee , a . j . heeger , nature photon . 2009 , 3 , 297 . 6 . e . zhou , j . cong , s . yamakawa , q . wei , m . nakamura , k . tajima , c . yang , k . hashimoto , macromolecules 2010 , 43 , 2873 . 7 . j . m . tour et al . j . am . chem . soc . 1997 , 119 , 5065 . 8 . j . m . tour et al . j . am . chem . soc . 1998 , 120 , 5355 . 9 . j . m . pomerantz et al . synth . met . 2003 , 135 - 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