Controllable synthesis of conjugated thio-phenylethyne-based compounds with different chain lengths

Article abstract of DOI:10.1039/c6ra05709h

Thiophenylethyne-based compounds have been extensively investigated for use in some molecular electronic devices. Based on thiophene and acetylene units, a series of oligomers and a polymer with different chain lengths were designed and synthesized via Sonogashira reaction in this work. These compounds were characterized by routine measurements to demonstrate that the optical bathochromic shifts and decreasing band gaps were caused by the increasing length of conjugated backbones. Meanwhile, synchrotron-based two-dimensional grazing-incidence X-ray diffraction was adopted to study the molecular stacking orientations with respect to the surfaces. The closer distance between the lamellar layers was shown to contribute to the better conducting property of the compounds. Moreover, the microscopic structural study directly provided further explanation for the good performance of the polymer in this system. Some top-gate field-effect transistors were fabricated via solution processing with the selected oligomers and the polymer. The polymer devices showed good charge transport mobility performance at 0.42 cm² V^-1 s^-1, with an on-off ratio of 1.59 × 10³, which are much better than those of the oligomers.

Full text of DOI:10.1039/c6ra05709h

View Article Online
View Journal
RSC Advances
This article can be cited before page numbers have been issued, to do this please use: W. Huang, H. Zhu,
Y. L. Huang, J. W. Yang and W. Wang, RSC Adv., 2016, DOI: 10.1039/C6RA05709H.
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. This Accepted Manuscript will be replaced by the edited,
formatted and paginated article as soon as this is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the Ethical guidelines still
apply. In no event shall the Royal Society of Chemistry be held
responsible for any errors or omissions in this Accepted Manuscript
or any consequences arising from the use of any information it
contains.
www.rsc.org/advances

Page 1 of 12
RSC Advances
View Article Online
DOI: 10.1039/C6RA05709H
Journal Name
RSCPublishing
ARTICLE
Controllable Synthesis of Conjugated Thio-
phenylethyne-based Compounds with Different Chain
Lengths
Cite this: DOI: 10.1039/x0xx00000x
Wei Huang,a Haoyun Zhu,a Yuli Huang,a Junwei Yang,a and Weizhi Wang*a
Received 00th January 2012,
Accepted 00th January 2012
Thiophenylethyne-based compounds have been extensively investigated for some molecular
electronic devices. Based on thiophene and acetylene units, a series of oligomers and polymer
owning different chain lengths were designed and synthesized via Sonogashira reaction in this
work. These compounds were characterized by some routine measurements to demonstrate that
the optical bathochromic shifts and decreasing band gaps were caused by the increasing
conjugated backbones. Meanwhile, synchrotron-based two-dimensional grazing-incidence X-
ray diffraction was adopted to study the molecular stacking orientations with respect to the
surfaces. The closer distance between the lamellar layers was testified to be a contribution to
the better conducting property of the compounds. Moreover, the microscopic structural study
directly provided further explanation for the good performance of the polymer in this system.
Some top-gate field-effect transistors via solution processing were fabricated with the selected
oligomers and the polymer. And the polymer devices showed nice performance of charge
transport mobility at 0.42 cm2V-1s-1 with an on-off ratio of 1.59 × 103, which were much better
than those of the oligomers.
DOI: 10.1039/x0xx00000x
www.rsc.org/
into the solid thin-films.19-22
Apart from the well-studied P3AT, the studies of other interesting
1. Introduction
conducting compounds with π-expanded conjugation, poly(2,5-
thienylene ethynylene) (PTE), seem to be little in the field of
conducting materials. This kind of polymer with low molecular
weight only consisting of alternating acetylene and thiophene units
was first reported by D. L. Trumbo in 1986.23 Since then, a few
scientists have devoted to the relevant work of these related
compounds, including linear type and macrocyclic type. In the early
days, Michael P. Cava and Takakazu Yamamoto24-25 have worked on
improving routines to synthesize PTE with higher molecular weight
or the preparation of some regiocontrolled polymers. Ronald
Breslow26 synthesized and examined a family of molecular wires
consisting of oligothiophenes and oligothiophenylethynes for the
construction of the molecular field-effect transistors (FETs). Giant
macrocyclic oligomers with 60π-180π electron systems, only
composed of thiophene and acetylene units, were synthesized by
Masahiko Iyoda via McMurry coupling reaction.27 At the same time,
the ordered self-assembly and aggregation structure on the surface of
the acetylene-based oligomers and polymers have received only
limited attention. Trolle R. Linderoth and Kurt V. Gothelf used
scanning tunneling microscopy (STM) to study the self-assembly of
several designed oligo(naphthylene-ethynylene) molecular rod
molecules when adsorbed on the surfaces.28 Yufeng Lu studied the
formation and self-assembly behavior of conjugated PTE/silica
nanocomposites.29 The π-conjugated structure of PTE showed its
potential to be applied in electronic devices like FETs, which were
composed of a substrate, a semiconductor, drain-source electrodes, a
Since the discovery of conducting polyacetylene, conducting
polymers, a class of polymers permitting delocalized charge carriers
transport with a sp2 structure, have been a popular researching field
in the material study.1-6 A lot of new conducting polymers are
stimulated to be synthesized by their possible applications like
sensors, organic photovoltaics, super capacitors, organic light-
emitting diodes, batteries, and so forth.7–11 Among the enormous
studies, some p-conjugated oligomers and polymers have been
widely investigated for fabricating molecular electronics.12-14
Actually, oligo- and polythiophenes are considered to be one of the
best candidates for applying to the components of electronic
devices,15-18 because some highly electronic conductive composites
would be produced by the oxidation of oligo- and polythiophenes. A
classic example is the research of poly(3-alkylthiophenes) (P3AT)
family in recent years, due to their good solubility, wide availability,
environmental stability and ease of processing from the solutions
a
State Key Laboratory of Molecular Engineering of Polymers,
Collaborative Innovation Center of Polymers and Polymer Composite
Materials, Department of Macromolecular Science, Fudan University,
Shanghai 200433, P. R. China.
* Corresponding Author
E-mail: weizhiwang@fudan.edu.cn. Tel: +86 021-65643836
† Electronic supplementary information (ESI) available. See DOI:
10.1039/cxxxxxxxxx
This journal is © The Royal Society of Chemistry 2013
J. Name., 2013, 00, 1-3 | 1

RSC Advances
Page 2 of 12
VJieowuArrtnicalelONnlainme e
ARTICLE
DOI: 10.1039/C6RA05709H
dielectric layer and a gate electrode.30 Masahiko Iyoda and his co- covered by the product films. The internal standard was
workers31 just reported on the surface structures and FET behavior of ferrocene under vacuum (4.8 eV), plus 0.1
M
macrocyclic oligothiophene with 6-mers. And their FETs containing tetrabutylammonium hexafluorophosphate (TBAPF6) in
the π-π stacking oligomers showed a good on-off ratio of 104, but acetonitrile was as the electrolyte. The measurements were
with a low charge carrier mobility of 2.8 x 10-3 cm2V-1s-1.
performed at a scan rate of 100 mV/s under the N2 protection.
According to the references, PTE attracted our attention because A platinum wire was the counter electrode, and Ag/AgNO3 was
of their interesting properties and assembly behavior. Accordingly, a the reference electrode. The mass spectra of the samples were
series of thiophenylethyne-based oligomers and polymers (1-4 and analyzed by matrix assisted laser desorption ionization-time of
PTE) were successfully designed and synthesized via Sonogashira the flight mass spectrometer (MALDI-TOF), AB SCIEX 5800.
reaction in this work. And they were studied by kinds of And the VARIO EL3 instrument (ELEMEN TAR, Germany)
characterizations like UV absorption, photoluminescence (PL) and was utilized for elemental analysis. The polarizing microscope
cyclic voltammetry (CV) to see how the increasing conjugated (POM) images were examined by a DM2500P polarizing
backbones affect the properties of the systematic compounds. In microscope at room temperature. The thickness of the films
addition, we used synchrotron-based two-dimensional grazing- formed in the FETs was measured on F40 film thickness tester.
incidence X-ray diffraction (2D-GIXRD) to directly learn molecular Synchrotron-based two-dimensional grazing-incidence X-ray
stacking of the synthesized compounds. Herein, 3, 4 and PTE were diffraction (2D-GIXRD) was implemented at BL14B1, with the
selected as the active semiconductor layer to fabricate some thin- help of Shanghai Synchrotron Radiation Facility. The grazing-
film FETs, to be tested their different performance. And the incidence angle was set to 0.25° and the wavelength was 0.124
molecular packing in films was utilized to provide further proof to nm. 0.2 wt% CH2Cl2 solutions of the compounds were spin-
the performance distinctions between the fabricated FETs and why coated on the substrates for 50 s to make the samples at the
these devices involving PTE possessed the best performance of rotation rate of 3500 r/m. Equipped with a Bruker SMART K
1
excellent charge carrier mobility and on-off current ratios in this CCD area detector and a rotating anode using graphite-
system.
monochromatic Mo Kα radiation (λ =0.71073 Å), a P4 Bruker
diffractometer was used to collect the whole X-ray
crystallographic data. A program of SAINT was for the data
processing, and another program of SADABS was employed
for calibrating the diffraction data. Based on the utilization of a
decay correction and the redundant reflections, an empirical
2. Experimental details
Materials
absorption correction was used as well. The final structure of
2
The whole chemicals and reagents used were selected and
purchased from chemical companies, J&K Scientific and
Sinopharm Chemical Reagent Company. Small sodium wires
and benzophenone were used to prepare dry toluene under the
nitrogen (N2) circumstance.
was resolved by utilizing the straight-ways procedure in the
program library of Bruker SHELXL and clarified by the least-
squares full-matrix approaches on F2. Some anisotropic thermal
parameters were utilized to refine the non-hydrogen atoms.
Simultaneously, the isotropic thermal parameters based on the
bonded carbon atoms and the hydrogen atoms were combined
together to calculate the positions.
Measurements and Characterization
On
a Bruker AVANCE III HD 400 MHz. FT-NMR
spectrometer, H and 13C nuclear magnetic resonance spectra
(NMR) were carried out in deuterated dichloromethane
(CD2Cl2). Chemical shifts were in ppm units and
tetramethylsilane (TMS; δ=0) was used as an internal standard.
Gel permeation chromatography (GPC) measurements were
recorded on a gel permeation chromatograph, Agilent/Wyatt
1260. The calibration was managed by employing
commercially available polystyrene. A UV-visible (UV-vis)
spectrophotometer, Perkin-Elmer Lambda 750 was employed
for UV spectra in dichloromethane (CH2Cl2) solution. PL
spectra were performed in CH2Cl2 solvent on a Photo
Technology International, Inc. QM40 fluorescent lifetime
spectrometers at room temperature. The PL quantum yields
1
FETs Fabrication.
H2O2/H2SO4, deionized water, methanol and acetone were
utilized in turn to wash the commercially available SiO2 (300
nm)/highly p-doped Si wafers. Then the clean wafers were
spin-coated by the synthesized compounds, 3, 4 and PTE in
CH2Cl2 solution (0.2 wt%) at a speed of 3500 r/min. These
semiconductor films were placed in a vacuum atmosphere to
evaporate the surplus solvent. The thickness of the thin film in
FETs was (494 2) nm. The gold drain and source electrodes
(the thickness was 50 nm, the channel width was 1 mm and the
channel length was 0.6 mm) were deposited on the thin
semiconductor films. A triblock copolymer, poly(styreneblock-
methyl methacrylate-block styrene) (MPMMA = 11.7 kg/mol, MW
(
ΦF) were estimated using fluorescein (ΦF = 92% in 0.1 M
NaOH) and quinine sulfate (ΦF = 54% in 0.1M H2SO4 solution)
as standards. And the fluorescent lifetimes were recorded on the
same QM40 spectrometers by means of a time-corrected single
=
19.3 kg/mol, MPS =5.2 kg/mol) and 1-ethyl-3-
methylimidazolium bis(trifluoromethylsulfonyl)imide in an
gravimetric analysis (TGA) measurement was done with a ethyl propionate solution were mixed to be ion gel as the
photon counting system at room temperature.
Thermal
thermo gravimetric analyzer (Perkin Elmer Pyris 1), heating
from 50 to 800 °C at a heating rate of 20 °C/min, in a N2 flow.
Differential scanning calorimetry (DSC) measurement was
implemented on the differential scanning calorimeter (TA
Q2000), one heat-cool cycle from 50 °C to 180 °C at a ramp of
20 °C/min in a dry N2 flow. Cyclic voltammetry (CV) was
operated on one electrochemical workstation (T30/FRA2). And
the glass-carbon electrolyte with a 0.08 cm2 cross section was
dielectric. The polymer films and the gold electrodes were all
covered by the prepared ionic solution. A 0.03 mm thick of Al
foil was adopted to cover the channels to be the top gate.
2 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 2012

Page 3 of 12
Journal Name
RSC Advances
View ArticAle ROnTliInCeLE
DOI: 10.1039/C6RA05709H
(147.6
ꢀ
L, 9.36 mmol) and TMS acetylene (0.60 g, 5.68 mmol)
Synthesis Procedures.
were added. After stirring at 80 °C for 22 h, the mixture was
then washed with NH4Cl solution. The organic layer was then
dried over anhydrous MgSO4 and collected by filtration. The
mixture was concentrated to dryness. And column
Synthesis of 1,2-di(thiophen-2-yl)ethyne (1)
2-bromothiophene (3.13 g, 19.20 mmol) and 2-
ethynylthiophene (2.17 g, 20.05 mmol) were both dissolved in
200 mL toluene under N2 atmosphere. After stirring the mixture
for 15 min to dissolve the starting materials, 15 mL
triethylamine, CuI (0.75 g, 3.97 mmol) and Pd(PPh3)4 (0.93g,
0.81 mmol) were added into the solution. In the dark
environment this reaction solution was kept at 80 °C, stirring
constantly for 12 h, then cooled down to room temperature. The
resulting mixture was concentrated to dryness, and the crude
product was purified through the column chromatography on
chromatography on silica gel provided pure
3 as yellow crystals
1
with a yield of 89.3% (1.71 g). H NMR (400 MHz, CD2Cl2), δ
(TMS, ppm): 7.40 – 7.37 (d, 2H), 7.34 – 7.31 (d, 2H), 7.21 –
7.18 (m, 4H), 7.07 – 7.04 (m, 2H); 13C NMR (100 MHz,
CD2Cl2), δ (TMS, ppm): 132.66, 132.51, 132.12, 128.30,
127.35, 124.90, 123.94, 122.22, 87.62, 86.86, 85.46. MS
(MALDI-TOF): m/z (%): 402.79 (100) [M]. Anal. Calcd for
C22H10S4 (402.57): C, 65.64; H, 2.50; Found: C, 65.94; H, 2.63.
silica gel to obtain
1 as a white crystal in a yield of 83.2% (3.03
1
g). H NMR (400 MHz, CD2Cl2), δ (TMS, ppm): 7.37 – 7.33
(d, 2H), 7.30 – 7.28 (d, 2H), 7.04 – 7.02 (m, 2H); 13C NMR
(100 MHz, CD2Cl2), δ (TMS, ppm): 132.14, 127.75, 127.22,
85.95. MS (MALDI-TOF): m/z (%): 190.34 (100) [M]. Anal.
Synthesis of 2,5-bis((5-(thiophen-2-ylethynyl)thiophen-2-
yl)ethynyl)thiophene (4)
4
1
was synthesized by the similar procedure as the described for
above. 2-bromo-5-(thiophen-2-ylethynyl)thiophene (7.10 g,
Calcd for C10H6S2 (190.28): C, 63.12; H, 3.18; Found: C, 26.36 mmol) and 2,5-diethynylthiophene (1.66 g, 12.56 mmol)
63.37; H, 3.21.
were added under N2 at first. CuI was 0.52 g (2.72 mmol),
Pd(PPh3)4 was 0.53 g (0.46 mmol) and triethylamine was 15
mL. Finally, the product was purified through a column with
Synthesis of 2,5-bis(thiophen-2-ylethynyl)thiophene (2)
2
silica gel to give
4 as orange crystals in a yield of 80.2% (5.12
was synthesized by the similar procedure as the described for
above. 3.58 g 2,5-dibromothiophene (14.79 mmol) and 3.28 g
1
g). H NMR (400 MHz, CD2Cl2), δ (TMS, ppm): 7.40 – 7.37
(d, 2H), 7.32 – 7.31 (d, 2H), 7.21 – 7.18 (m, 6H), 7.07 – 7.04
(m, 2H); 13C NMR (100 MHz, CD2Cl2), δ (TMS, ppm): 132.67,
132.58, 132.55, 132.12, 128.31, 127.35, 124.98, 124.42,
123.87, 87.67, 87.13, 86.80, 85.45. MS (MALDI-TOF): m/z
(%): 509.05 (100) [M].Anal. Calcd for C28H12S5 (508.72): C,
66.11; H, 2.38; Found: C, 66.23; H, 2.42.
1
2-ethynylthiophene (30.33 mmol) were added under N2 at first.
CuI was 0.60 g (3.15 mmol), Pd(PPh3)4 was 0.67 g (0.58 mmol)
and triethylamine was 15 mL. Finally, the product was purified
through a column with silica gel to give
2 as dark yellow
1
crystals in a yield of 86.5% (3.79 g). H NMR (400 MHz,
CD2Cl2), δ (TMS, ppm): 7.39 – 7.35 (d, 2H), 7.32 – 7.31 (d,
2H), 7.17 (s, 2H), 7.06 – 7.03 (m, 2H); 13C NMR (100 MHz,
CD2Cl2), δ (TMS, ppm): 132.60, 132.09, 128.23, 127.34,
Polymerization of poly(thienyleneethynylene)s (PTE)
124.44, 122.30, 87.38, 85.54. MS (MALDI-TOF): m/z (%): PTE was synthesized by the similar procedure as the described
296.53 (100) [M]. Anal. Calcd for C16H8S3 (296.43): C, 64.83; for
H, 2.72; Found: C, 64.92; H, 2.85.
1 above. 1.49 g 2,5-diethynylthiophene (11.27 mmol) and
2.79 g 2,5-dibromothiophene (11.53 mmol) were added into
200 mL toluene under N2. CuI was 0.45 g (2.38 mmol),
Pd(PPh3)4 was 0.48 g (0.42 mmol) and triethylamine was 15
mL. This reaction mixture was stirred at 80 °C for 24 h. In the
end, the product was purified through a column with silica gel
Synthesis of 1,2-bis(5-(thiophen-2-ylethynyl)thiophen-2-yl)ethyne
(3)
A flask equipped with a magnetic stirrer was charged with 2-
bromo-5-(thiophen-2-ylethynyl)thiophene (2.56 g, 9.51 mmol)
coupled with 150 mL toluene. Then CuI (0.21 g, 1.12 mmol),
Pd(PPh3)4 (0.59 g, 0.51 mmol), DBU (20 ml, 0.23 mol), H2O
1
to give PTE as crimson solids in a yield of 64.3% (2.75 g). H
NMR (400 MHz, CD2Cl2), δ (TMS, ppm): 8.15 – 8.04 (m, 1H),
7.24 – 7.20 (m, 1H); Anal. Calcd for C6H2S (106.16): C, 67.82;
H, 0.02; Found: C, 67.78, H, 0.03.
Scheme 1. Procedures for the synthesis of 1-4 and PTE. i. toluene, triethylamine, CuI, Pd(PPh3)4, 80 °C; ii. toluene, DBU, CuI, Pd(PPh3)4,
H2O, 80 °C.
This journal is © The Royal Society of Chemistry 2012
J. Name., 2012, 00, 1-3 | 3

RSC Advances
Page 4 of 12
VJieowuArrtnicalelONnlainme e
ARTICLE
DOI: 10.1039/C6RA05709H
1
Fig. 1 The H NMR spectrum of 2 in CD2Cl2, and the signal peak at round 5.3 ppm is attributed to CD2Cl2. The inserted picture is ORTEP
drawing of 2.
indices (PDIs) of 1.22, which was calculated by means of
Mw/Mn. Actually, the high Mn and narrow PDIs are advantages
for better film and fiber formation, which are favorable to the
later fabrication of FETs.
3. Results and discussions
Synthesis and characterization.
Thermal properties.
2-Ethynylthiophene
and
2,5-diethynylthiophene
were
The thermal property of the semiconductor materials is an
important factor to form the flexible thin-film FETs. Thus, the
thermal measurements of PTE were carried out in the N2
atmosphere. TGA and DSC curves were both shown in Fig. 2.
The onset decomposition temperature (the weight of the sample
decreased to 95%) of PTE was 248 °C, which was assigned to
the long and rigid acetylenic structure. Although the thermal
stability of PTE was inferior to that of the corresponding
synthesized by ourselves referring to some mature methods in
the related papers.32,33 By using the monomers and the
Sonogashira coupling reaction,34 the resulting oligomers
1-4
and the polymer PTE with good yield were achieved by the
synthetic procedures clearly outlined in Scheme 1. All of the
pure products were finally obtained by column chromatography
on silica gel. Intriguingly, the crystals of 1-4 varied from white
to orange were recrystallized from their solutions. Luckily, the
X-ray crystallographic analysis was used to identify the
phenylacetylene-based
polymers,35
the
decomposition
temperature up to around 250 °C is high enough to be applied
in electronic devices. Interestingly, the DSC heating traces of
PTE in Fig. 2b exhibited its glass-transformation temperature
at around 129 °C in the amorphous section. In general, PTE
possessed good thermal stability because of its well-defined
structure containing a long conjugated backbone. The nice
thermal property of PTE could be vital for achieving the FETs
with high performance.
accurate crystal structure of
And its corresponding single-crystal data were collected in
Table S1 in the supporting information. H NMR is a common
and effective method to characterize the products. Herein, H
2 as the inserted picture in Fig. 1.
1
1
NMR spectrum of
2 in CD2Cl2 was shown as an example in Fig.
1
1. In this H NMR spectrum, the resonance signals between
7.00 ppm and 7.50 ppm were exactly the characteristic peaks of
protons on thiophene. Additionally, the rest oligomers and PTE
1
were carefully purified and clearly characterized by solution H
NMR and 13C NMR, and all of their spectra were displayed in
the supporting information (Fig. S1 – Fig. S9). Moreover, the
molecular weight of the oligomers could be directly measured
by MALDI-TOF, and the mass spectral data of 1-4 were also
added in the supporting information to affirm their successful
synthesis as a further proof (Fig. S10 – Fig. S13).
The elemental polymerization of PTE took 24 h in a mild
reaction temperature, 80 °C. In fact, there were some red
precipitations to appear in the reaction solution at the later stage.
In the end of the reaction, some crimson precipitations were
separated out from the solution, which portended the possible
high molecular weight of the product. Then GPC measurement
of the product, with polystyrene as the standard and THF as the
eluent (Fig. S14 in the supporting information) was in
accordance with the previous anticipation. The number-average
molecular weight (Mn) determined of PTE was up to 45.0
kg/mol. At the same time, it possessed narrow polydispersity
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 2012

Page 5 of 12
Journal Name
RSC Advances
View ArticAle ROnTliInCeLE
DOI: 10.1039/C6RA05709H
in solution possessed strong fluorescence while its fluorescence
became weakly emissive in the solid state. This is a remarkable
phenomenon named aggregation-caused quenching (ACQ), the
emissive light of a conventional luminophore is weakened in
the condensed state in comparison to them in solution. This is
due to the formation of molecular aggregation, which facilitates
nonradiative pathways and exciton interactions.36-38 ACQ
appears when the molecular chains of the polymers with certain
conjugated degree aggregate more closely in the solid film, so
this is the reason that only PTE pronouncedly showed this
phenomenon. Particularly, parts of molecular chains of PTE
were able to pack closer by the lamellar and π-π stacking due to
the massive thiophene rings and the planarization of the
molecular chains. ACQ is a big obstacle to the luminophores,
but an advantage for materials applied as a semiconductor.
Because there is less energy wasted for emitting light during the
process of transmitting electrons. So PTE possessed great
potential to be applied in electric devices.
Moreover, the detailed UV-vis spectra of the products were
displayed in Fig. 3d. Besides the PL emission wavelength in
dilute CH2Cl2 solution (λem), the corresponding spectral data
like absorption wavelength (λabs), PL emission wavelength in
the condensed state (λ’em), the quantum yields (ΦF) in dilute
CH2Cl2 solution using fluorescein (ΦF = 92% in 0.1M NaOH
solution) and quinine sulfate (ΦF = 54% in 0.1M H2SO4
solution) as the references, and fluorescent lifetime (τ) were all
collected in Table 1. 1-4 and PTE possessed absorption
wavelengths at 315 nm, 362 nm, 379 nm, 402 nm and 430 nm
respectively, resulting in the same red-shift rule with the
extended conjugated degree.
Fig. 2 (a) The TGA curve of PTE; (b) The DSC curve of PTE
.
Optical properties.
Additionally, ΦF and
τ
are some other convincing evidences
and PTE in
for the former discussion. The data of ΦF for
1-4
Even though the solubility of compounds was becoming worse
with the growing length of backbones, they were still dissolved
in the organic solvent like CH2Cl2. So, all the liquid PL
measurements adopted CH2Cl2 as the solution of the samples.
From Fig. 3a, the upper pictures were the compounds in CH2Cl2
solutions under 365 nm UV irradiation. It was clearly observed
that the fluorescence of the compounds changed from purple to
yellow following a red-shift rule, which could be testified
clearly by their PL spectra in the dilute CH2Cl2 solution (Fig.
3b). And the corresponding emission wavelengths from 412 nm
to 524 nm could be found in Table 1. It was roughly observed
by naked eyes that the fluorescent intensity was getting stronger
with the longer conjugated backbones, except for the very weak
solutions were significantly increasing with the growing
backbones, 2.94%, 36.23%, 67.32%, 85.60% and 91.37%. On
the other hand, the high efficiency was also attributed to the
rigid structure of the backbones. The excited species of the
luminescence in solution could relax much more slowly by the
restriction of the intramolecular rotations. At the same time, the
figure of obtained
S15). The lifetimes of
0.99 ns, 1.02 ns and 1.18 ns. And
τ
was in the supporting information (Fig.
were increasing as expected, 0.37 ns,
of PTE with the high
1-4
τ
molecular weight was much more than those of the oligomers,
perfectly correlating with changes of the growing ΦF. Unlike
the phenomenon in solutions, the ΦF of PTE in the condensed
state weakened dramatically. This ACQ phenomenon and its
reason have been mentioned before. Even though it was a pity
not to collect the PL emission spectrum of PTE in the solid
state because of its weak fluorescence, it was still clearly
observed by naked eyes that the condensed PTE emitted
crimson fluorescence. This indicated that the PL emission peak
of PTE in solid must locate in the red range (> 600 nm). This
could be explained by the more planar chains of PTE to pack
fluorescence of
extent of the
molecular electronic energy level, which could cause a
bathochromic shift in PL emission. But the backbone of was
1
. The effective conjugated length enhanced the
π
-electrons of delocalization and narrowed the
1
too short to effectively transmit delocalized electrons.
Compared to the fluorescence of the compounds in solutions,
there was bathochromic shift for the fluorescence of 3, 4 and
PTE in their solid state (the lower pictures in Fig. 3a). It was
the aggregation of the molecules or molecular chains to lead to
the marked bathochromic shift. And Fig. 3c showed the PL
closer than that of
means of the strong lamellar and
1
-
4
. And the small interplanar spacing by
stacking allowed the
π-π
electrons transfer more easily, resulting in the obvious red-shift
phenomenon.
spectra of
2, 3 and 4 in the solid state. The spectra of 1 and
PTE were not involved, because their fluorescence intensity
was too weak to be detected by the instrument. Unlike 1, PTE
This journal is © The Royal Society of Chemistry 2012
J. Name., 2012, 00, 1-3 | 5

RSC Advances
Page 6 of 12
VJieowuArrtnicalelONnlainme e
ARTICLE
DOI: 10.1039/C6RA05709H
Fig. 3 (a) The upper fluorescent photographs are the compounds in CH2Cl2 solutions under 365 nm UV irradiation, and the lower
fluorescent pictures are the corresponding solid samples under 365 nm UV irradiation; (b) The normalized PL emission spectra of 1-4
and PTE in CH2Cl2 solutions; (c) The normalized PL emission spectra of 2, 3 and 4 in solid state; (d) The normalized absorbance
spectra of 1-4 and PTE in CH2Cl2 solutions.
Table 1 UV-vis Absorptions and PL Data of 1-4 and PTE in CH2Cl2 Solution.
Compounds
λabs a (nm)
λem b(nm)
λ'em c(nm)
ΦF d (%)
2.94
τ e (ns)
0.37
315
412
-
1
362
442
443
485
541
-
36.23
67.32
85.60
91.37
0.99
2
379
466
1.02
3
402
490
1.18
4
430
524
1.85
PTE
a Absorption maximum in dilute CH2Cl2 solution. b Emission maximum in dilute CH2Cl2 solution. c Emission maximum in the solid film. d Quantum
yield estimated with fluorescein (ΦF = 92% in 0.1 M NaOH) and quinine sulfate (ΦF = 54% in 0.1M H2SO4 solution) as the references. e Fluorescent
lifetime
relationships, the HOMO values were always derived from the
Electrochemical properties.
following classical formulas: HOMO = -e(Eonset-ox-0.0468 V)-
4.8 eV (where the value 0.0468 V is for FOC vs Ag/Ag+),
For the sake of an explanation for the pronounced
bathochromic-shift fluorescence and figuring out the
relationship between the optical features and their intrinsic
electronic structures, CV measurements of the resulting
compounds were carried out as usual to measure the
electrochemical redox behavior of them. The energy band gaps
(ꢀEg), the highest occupied molecular orbital (HOMO) and the
lowest unoccupied molecular orbital (LUMO) are the most
essential parameters in this electrochemical measurement. The
LUMO = ꢀEg + HOMO.
The corresponding data of the compounds, as well as the
energy level parameters, were all displayed in Table 2 in turn.
The Eonset-ox values of 1-4 and PTE appeared at 0.97, 0.89, 0.51,
0.43 and 0.38 V, respectively. And the values were decreasing
in pace with the increasing conjugations as expected. Owing to
the Eonset-ox values and their oxidation process, the HOMO
energy levels of the compounds were estimated to be -5.72, -
5.64, -5.26, -5.18 and -5.13 eV in sequence, referring to the
former equation. Then PL emission wavelengths in the
solutions of compounds were combined with the above data,
the final ꢀEg values of all the compounds were calculated to be
2.98, 2.81, 2.66, 2.53 and 2.37 eV, respectively.
original CV curves of
figure in the supporting information (Fig. S16
1
-
4
and PTE were all arranged in one
. Their onset
)
oxidation potential (Eonset-ox) obtained from CV in acetonitrile
could be acquired from these curves. Then, on the basis of the
6 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 2012

Page 7 of 12
Journal Name
RSC Advances
View ArticAle ROnTliInCeLE
DOI: 10.1039/C6RA05709H
The existing difference in band gaps and HOMO/LUMO
values between the oligomers and PTE was mainly induced by
their different extents of conjugation. The
π-extended
conjugated backbones formed the main channels for the
transmitting electrons. These electrochemical values could meet
quite well with the measurements of the compounds in the
mentioned optical properties, and were broadly consistent with
the incremental molecular conjugation degree. Therefore, these
gradually narrowing band gaps with the increasing conjugated
backbones fairly demonstrated a strong evidence that a more
extended conjugated structure could lower the energy levels for
the electronic migration in the conjugated backbones.
Table 2 Electrochemical Properties of 1-4 and PTE.
Eg
(eV)
HOMO
(eV)
Eonset-ox
(V)
LUMO
(eV)
Compounds
2.98
-5.72
0.97
-2.74
-2.83
-2.60
-2.65
-2.76
1
2.81
2.66
2.53
2.37
-5.64
-5.26
-5.18
-5.13
0.89
0.51
0.43
0.38
2
3
4
PTE
Morphology characterization and 2D-GIXRD.
Fig. 4 The POM images under room light on the left and UV
exposure on the right of (a)1, (b)2, (c)3, (d)4, which were prepared
by the slow evaporation of the CH2Cl2 solvent at 1 mg/mL.
The crystals of the oligomers were easily recrystallized from
their CH2Cl2 solution at room temperature. Thus, POM was
utilized to study their morphology. It was obvious that
1-4
possessed different crystal structures and different fluorescence
from Fig. 4, respectively (left pictures were under the room
The packing of the molecules contributes to both the transfer
integral and reorganization energy.39 And the charge carrier
mobility in conjugated polymers is mainly dependent on the
charge-hopping transport mechanism.40,41 Hence the
morphology and molecular arrangement of semiconducting
layers take on significant roles in the charge transport between
molecules, which are essential to the performance of FETs.42-44
Therefore, 2D-GIXRD was employed as an effective technique
to analyze the molecular orientation and crystalline structure in
thin films of the compounds. The fabricated films were spin-
coated on the clean Si/SiO2 wafers from 0.2 wt % CH2Cl2
solutions at room temperature. As the examples, 2D-GIXRD
patterns of 3 and PTE were displayed in Fig. 5. And the inserted 3D
models were schematic diagrams of the molecular packing
orientations in their films.
light and the right ones were under UV exposure). Crystal
was tiny needle with light blue fluorescence. showed bigger
plate-like crystals with a blue light. And owned green thin-
plate crystals, plus formed yellow flower-like ones. The
1
2
3
4
oligomers followed the red-shift and the bigger crystal size
rules with the increasing backbones. This demonstrated that the
growing conjugated degree was a benefit for the ordered
aggregation, which was a reason for the strong ACQ
phenomenon of PTE. In a word, the greater ordered packing
morphology was dominant to own better charge-carrier mobility.
This journal is © The Royal Society of Chemistry 2012
J. Name., 2012, 00, 1-3 | 7

RSC Advances
Page 8 of 12
VJieowuArrtnicalelONnlainme e
ARTICLE
DOI: 10.1039/C6RA05709H
molecules.49-51 The spacing along the lamellar stacking and the
intermolecular stacking of PTE were both smaller than those of
3
. This was a further proof of the strong molecular aggregation
of PTE, which was in accord with the former characterizations.
Additionally, the 2D-GIXRD patterns of the rest oligomers
and were arranged in the supporting information (Fig. S17 –
1, 2
4
Fig. S19). In this system, the lamellar spacing gradually decreased
from 3.00, 2.86, 2.73, 2.62 to 2.09 nm for 1-4 and PTE. The closer
molecular stacking was dependent on the increasing conjugated
degree.
In general, the 2D-GIXRD results demonstrated that the
molecular stacking of compounds 1-4 were edge-on orientation
with respect to the substrates, and the most molecular chains in
PTE were stacking with face-on orientation. Actually, they
possessed both lamellar stacking and π-π stacking in their thin
films. Combined with the other characterizations like PL, the
decreasing distance in the lamellar structure with the growing
backbones was direct evidence to the stronger molecular
aggregation of PTE in the condensed state. Thus, this series of
compounds were expected to be applied in high performance
FETs.
FETs characterization.
Based on the above measurements, the acquired compounds,
especially PTE with a high conjugated degree, had been proved
to possess electronic conductivity and good solubility. This
series of compounds showed potential to be a part of some
devices like solar cells, diodes, FETs, and so on. Herein,
3 and
4, selected as the examples of the oligomers, and the polymer
PTE were used as the semiconductor layer in fabricating FETs
to measure their electronic transmission capacity. As one of the
most important parts in FETs, the gate dielectric always utilizes
some typical inorganic oxides like SiO2, Al2O3 and so on.52-54
However, it was a fascinating part in our FETs that ion gel was
employed to form the gate dielectric layer.55,56
Notwithstanding, several research groups in the world have
manufactured some high-performance FETs with inorganic
dielectrics, the organic dielectrics are still in the favourable
position because of their prominent features. Besides the
remarkable mechanical flexibility just like most of the organic
materials, the extraordinarily high capacitance permitting a low
voltage operation is another fascinating advantage. A low
working voltage is beneficial to decrease the consuming heat in
the working devices. So it is an effective way to take advantage
of the ion gel as the dielectric combining with the conjugated
compounds as the semiconductor to fabricate some possible
high-performance FETs.
On the top of Fig. 6, this simple 3D model exhibited the geometric
structure of a sort of top-gate FET with the ion gel covered on gold
electrodes as the dielectric layer and aluminium as the top gate. The
Si/SiO2 substrates were coated by the selected compounds (3, 4 and
PTE) as the thin-film semiconductor layer via direct solution
processing. Besides, there were vapour-deposited gold electrodes
between the dielectric and the semiconductor layer. The detailed
manufacturing process could be discovered in the former
experimental section. Fig. 6a, 6b and 6c were the typical output
characteristic curves of the FETs with the samples drop-cast on the
substrates, followed by evaporating the surplus solvent in a vacuum
environment. The key parameters like drain-source current (IDS) and
gate voltage (VG) characteristics at VDS = 1.0 V could be obtained
Fig. 5 The 2D-GIXRD patterns of (a) 3 and (b) PTE. The insets in
(a, b) are schematic diagrams of the orientations of the aggregation
structure with respect to the substrate in the films.
The ordered molecular stacking along the direction in the
conducting channel is good for charge transport. The 2D-GIXRD
study of some thiophene-based compounds like P3HT, showed
similar diffraction patterns to our results.45 Consistently, the
(h00)
and (010) planes reflections indicate along the qz out-of-plane and
qxy in-plane axes, respectively. (h00) planes are used as a criterion
for the lamellar stacking and (010) reflection is due to the π-π
intermolecular stacking.46-48 As shown in Fig. 5a, the three peaks
along the qz axe were assigned to (100), (200) and (300) diffractions
from the lamellar structure, respectively. Simultaneously, the peak
on qxy axe was (010) diffraction of the π-π stacking. This diffraction
pattern of 3 could be attributed to the edge-on orientation, which
was good for carrier conduction along the backbones. And
according to the (010) diffraction, the 2D-GIXRD patterns of PTE
in Fig. 5b showed that there was molecular face-on orientation in the
film. As the depiction in the inserted models schematically, this
orientation could attenuate the carrier conduction along the π-π
stacking direction. The lamellar spacing and the intermolecular
spacing of
3 were 2.73 nm and 0.46 nm respectively, according
to the (100) plane in this area of qz = 3.3-3.7 nm-1 (out of plane)
and the (010) reflection in the area along the qxy = 14.3 nm-1 (in
plane) axis. Obtained from the diffraction patterns of PTE, the
d(100) of PTE was 2.09 nm at qz =2.9-3.9 nm-1 and its d(010)
at qxy = 14.1 nm-1 was calculated to 0.44 nm. Probably, there
was no steric hindrance caused by side chains to make the
spacing of the samples much smaller than some other organic
for these curves. Meanwhile, their transfer characteristic curves and
1/2
∣IDS
∣
versus ∣VG∣curves of the FETs were depicted in Fig.
6d, 6e and 6f. And the output and transfer curves both distinctly
8 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 2012

Page 9 of 12
Journal Name
RSC Advances
View ArticAle ROnTliInCeLE
DOI: 10.1039/C6RA05709H
affirmed that FETs with the organic semiconductor and ion gel 0.22 cm2V-1s-1 with a Ion/Ioff of 1.04×103. Compared with the
emerged p-channel FET characteristics.
oligomers, PTE showed much better performance of 0.42 cm2V-1s-1
with a Ion/Ioff of 1.59×103. The extended conjugated degree and the
closer aggregation structures had a great influence indeed on the
conductive properties according to the above comparisons.
Even if there were lots of FETs with very high mobility values
reported in recent years, some of those devices showed quite low
Ion/Ioff values even at a high working voltage and some could just
work at a very high working voltage.57-59 The higher working
voltage meant to consume more energy to generate useless heat. By
compared, PTE possessed good thermal and air stability, which was
an indispensable condition for stable electronic devices. The nice
solubility of PTE was propitious to employ simple solution
processing. Besides the good mobility with a high enough Ion/Ioff
value of the fabricated FETs consisting of PTE, they even could
work at a low voltage (< 7 V). Low operating voltage was a practical
merit for the organic materials to be applied in FETs as well. In
short, the good ꢀ and Ion/Ioff of the FETs involving PTE meet with
its good conducting properties as expected.
4. Conclusions
In summary, a series of oligomers and polymers consisting of
alternating thiophene and acetylene units (1-4 and PTE) were
designed and synthesized via Sonogashira reaction. Then the
compounds with different chain lengths were characterized by a
1
lot of routine measurements like H and 13C NMR, MALDI-
TOF, UV/vis absorption, PL and CV. The measured results
demonstrated not only the successful synthesis of the targeting
compounds, but also the influence caused by the growing
conjugated backbones on the optical property and electronic
conduction. The bathochromic shifts and decreasing band gaps
showed the potential nice performance of PTE with the longest
backbones as the semiconductor layer in FETs. And the π-
Fig. 6 The 3D model on the top shows the geometric structure of the
fabricated top-gate FETs; Output characteristics curves of the FETs
consist of (a) 3, (b) 4 and (c) PTE; Transfer characteristic curves at
VDS = 1.0 V and the square root of the absolute values of drain
current as a function of gate voltage for (a) 3, (b) 4 and (c) PTE. Its
calculated charge carrier mobility (ꢀ) maximum values and the on-
to-off current ratios (Ion/Ioff) are 0.13 cm2V-1s-1 and 8.46 x 102 for 3;
0.22 cm2V-1s-1 and 1.04 x 103 for 4; 0.42 cm2V-1s-1 and 1.59 x 103
for PTE, respectively.
extended polymer also possessed enough solubility and thermal
stability to benefit fabricating thin-film devices. In the actual
testing, the FETs involving PTE truly owned good performance
of ꢀ= 0.42 cm2V-1s-1, which was much better than 0.13 and 0.22
cm2V-1s-1 of those with the selected oligomers (3 and 4). Owing to
the related measurements, it was clear that the higher molecular
weight and more extended conjugated backbone were extraordinarily
helpful to the conducting polymers applied in mechanically flexible
and high-performance electronic devices.
From the perspective of molecular packing structure adsorbed on
surfaces, the employment of 2D-GIXRD was an interesting part to
provide a direct explanation for the good performance of PTE in this
system. The longer conjugated chains of PTE resulted in the notably
ordered and closer orientation on the surface, which promoted the
electronic delocalization quintessential for local charge transports
along the π-π stacking direction. It was pronounced that the
distance between the molecular lamellar layers of PTE, 2.09 nm,
was less than those of the oligomers (1 was 3.00 nm, 2 was 2.86 nm,
3 was 2.73 nm and 4 was 2.62 nm). In a word, this study of the
thiophenylethyne-based system indicated the importance of the
conjugated backbones and the molecular stacking orientations of the
conducting oligo- and polymers. What’s more, it showed the
potential performance of PTE practically applied in the flexible
devices like FETs.
As shown in Fig. 6d, 6e and 6f, a linear relationship within a
limited range on the ∣IDS
∣
1/2 versus ∣VG ∣curve obtained at VDS
= 1.0 V, the threshold voltages (Vth) of FETs involving 3, 4 and PTE
were evaluated to -1.81 V, -2.14 V and -2.22 V respectively. In this
work, the gate oxide capacitance per unit area of the applied ion gel
was 20 ꢀF/cm2. From the transfer characteristics, there was a low
conductivity at the low VG, which suggested an excellent air stability
thanks to some low HOMO levels of 3, 4 and PTE (-5.26, -5.18
and -5.13 eV). According to the Vth values and the transfer
characteristics, some ꢀ values were calculated by several groups of
IDS and VG values substituted into the metal-oxide semiconductor
FET formula. And the detailed calculations were displayed in the
supporting information. In fact, the final ꢀ values of the FETs were
picked from several typical results. The figures of the calculated
mobility plots versus the related gate voltages for 3, 4 and PTE were
also placed in the supporting information (Fig. S20). The highest ꢀ
value was taken as the adoptive standard. The optimal value of ꢀ for
3 was 0.13 cm2V-1s-1 with a Ion/Ioff of 8.46×102, which was not a
remarkable performance. Meanwhile, 4 possessed better ꢀ value of
Acknowledgements
This work was financially supported by the National Natural
Science Foundation of China (21274027 and 20974022) and the
Innovation Program of Shanghai Municipal Education
This journal is © The Royal Society of Chemistry 2012
J. Name., 2012, 00, 1-3 | 9

RSC Advances
Page 10 of 12
ARTICLE
VJieowuArrtnicalelONnlainme e
DOI: 10.1039/C6RA05709H
Commission (15ZZ002). The FETs were fabricated and probed
in the Micro-Nano Processing and Preparation Public
Laboratory, Fudan University. The synchrotron-based 2D-
GIXRD measurement was supported by Shanghai Synchrotron
Radiation Facility (15ssrf00474).
and P. W. M. Blom, Adv. Funct. Mater., 2006, 16, 699-708.
21 Q. Liu, Z. Liu, X. Zhang, L. Yang, N. Zhang, G. Pan, S.
Yin, Y. Chen and J. Wei, Adv. Funct. Mater., 2009, 19,
894-904.
22 W. D. Oosterbaan, J. Bolsée, L. Wang, V. Vrindts, L. J.
Lutsen, V. Lemaur, D. Beljonne, C. R. McNeill, L.
Thomsen, J. V. Manca and D. J. M. Vanderzande, Adv.
Funct. Mater., 2014, 24, 1994-2004.
References
1-59
23 D. L. Trumbo and C. S. Marvel, J. Polym. Sci., Part A:
Polym. Chem., 1986, 24, 2231-2238.
24 F. Chimenti, L. D'Ilario, A. Ettorre, E. Muraglia, G.
Ortaggi and G. Sleiter, J. Mater. Sci. Lett., 1992, 11, 1532-
1533.
25 G. V. Tormos, P. N. Nugara, M. V. Lakshmikantham and
M. P. Cava, Synth. Met., 1993, 53, 271-281.
26 H. Hayashi and T. Yamamoto, Macromolecules, 1997, 30,
330-332.
1 K. Akagi, Chem. Rev., 2009, 109, 5354-5401.
2 B. Zhu, S. Luo, H. Zhao, H. Lin, J. Sekine, A. Nakao, C.
Chen, Y. Yamashita and H. Yu, Nat. Commun., 2014, 5,
4304-4309.
3 S. Soylemez, S. O. Hacioglu, M. Kesik, H. Unay, A. Cirpan
and L. Toppare, ACS Appl. Mater. Interfaces, 2014, 6,
18290-18300.
4 Z. Wang, Q. Liu and B. Ding, Chem. Mater., 2014, 26,
3364-3367.
27 M. Iyoda, C. R. Chim., 2009, 12, 395-402.
28 J. R. Cramer, Y. Ning, C. Shen, A. Nuermaimaiti, F.
Besenbacher, T. R. Linderoth and K. V. Gothelf, Eur. J.
Org. Chem., 2013, 2013, 2813-2822.
29 B. McCaughey, C. Costello, D. Wang, J. E. Hampsey, Z.
Yang, C. Li, C. J. Brinker and Y. Lu, Adv. Mater., 2003, 15,
1266-1269.
5 S. Takamatsu, T. Lonjaret, E. Ismailova, A. Masuda, T. Itoh
and G. G. Malliaras, Adv. Mater., 2015, 4, 249-252.
6 J. Li, S. J. Yoon, B. Hsieh, W. Tai, M. O Donnell and X.
Gao, Nano Lett., 2015, 15, 8217-8222.
7 C. M. Hangarter, N. Chartuprayoon, S. C. Hernández, Y.
Choa and N. V. Myung, Nano Today, 2013, 8, 39-55.
8 Z. Chen, J. W. F. To, C. Wang, Z. Lu, N. Liu, A. Chortos, L.
Pan, F. Wei, Y. Cui and Z. Bao, Adv. Energy Mater., 2014,
4, 1400207
30 Y. Guo, G. Yu and Y. Liu, Adv. Mater., 2010, 22, 4427-
4447.
31 M. Iyoda, K. Tanaka, H. Shimizu, M. Hasegawa, T.
Nishinaga, T. Nishiuchi, Y. Kunugi, T. Ishida, H. Otani, H.
Sato, K. Inukai, K. Tahara and Y. Tobe, J. Am. Chem. Soc.,
2014, 136, 2389-2396.
32 S. Uttiya, L. Miozzo, E. M. Fumagalli, S. Bergantin, R.
Ruffo, M. Parravicini, A. Papagni, M. Moret and A.
Sassella, J. Mater. Chem. C, 2014, 2, 4147-4155.
33 T. X. Neenan and G. M. Whitesides, J. Org. Chem., 1988,
53, 2489-2496.
34 J. Li and Y. Pang, Macromolecules, 1997, 30, 7487-7492.
35 C. M. Vosloo and A. S. Luyt, J. Therm. Anal., 1995, 44,
1261-1275.
36 P. Wang, C. J. Collison and L. J. Rothberg, J. Photochem.
Photobiol., A, 2001, 144, 63-68.
37 W. Z. Yuan, P. Lu, S. Chen, J. W. Y. Lam, Z. Wang, Y.
Liu, H. S. Kwok, Y. Ma and B. Z. Tang, Adv. Mater., 2010,
22, 2159-2163.
38 N. Zhao, J. W. Y. Lam, H. H. Y. Sung, H. M. Su, I. D.
Williams, K. S. Wong and B. Z. Tang, Chem. Eur. J., 2014,
20, 133-138.
39 J. L. Brédas, J. P. Calbert, D. A. D. S. Filho and J. Cornil,
Proc. Natl. Acad. Sci. U. S. A., 2002, 99, 5804-5809.
40 Z. Chen, P. Müller and T. M. Swager, Org. Lett., 2006, 8,
273-276.
41 A. Salleo, R. J. Kline, D. M. DeLongchamp and M. L.
Chabinyc, Adv. Mater., 2010, 22, 3812-3838.
42 R. J. Kline, M. D. Mcgehee and M. F. Toney, Nat. Mater.,
2006, 5, 222-228.
9 Q. Zhang, B. Li, S. Huang, H. Nomura, H. Tanaka and C.
Adachi, Nat. Photonics, 2014, 8, 326-332.
10 K. Sun, Z. Xiao, S. Lu, W. Zajaczkowski, W. Pisula, E.
Hanssen, J. M. White, R. M. Williamson, J. Subbiah, J.
Ouyang, A. B. Holmes, W. W. H. Wong and D. J. Jones,
Nat. Commun., 2015, 6, 6013.
11 Z. Wu, L. Chen, J. Liu, K. Parvez, H. Liang, J. Shu, H.
Sachdev, R. Graf, X. Feng and K. Müllen, Adv. Mater.,
2014, 26, 1450-1455.
12 X. Guo, J. P. Small, J. E. Klare, Y. Wang, M. S. Purewal, I.
W. Tam, B. H. Hong, R. Caldwell, L. Huang, S. O'Brien, J.
Yan, R. Breslow, S. J. Wind, J. Hone, P. Kim and C.
Nuckolls, Covalently Bridging Gaps in Single-Walled
Carbon Nanotubes with Conducting Molecules. Science
2006, 311, 356-359.
13 X. Jin, D. Sheberla, L. J. W. Shimon and M. Bendikov, J.
Am. Chem. Soc., 2014, 136, 2592-2601.
14 A. Jain and S. J. George, Mater. Today, 2015, 18, 206-214.
15 P. Leclère, M. Surin, P. Viville, R. Lazzaroni, A. F. M.
Kilbinger, O. Henze, W. J. Feast, M. Cavallini, F. Biscarini,
A. P. H. J. Schenning and E. W. Meijer, Chem. Mater.,
2004, 16, 4452-4466.
16 L. Zhang, N. S. Colella, B. P. Cherniawski, S. C. B.
Mannsfeld and A. L. Briseno, ACS Appl. Mater. Interfaces,
2014, 6, 5327-5343.
17 C. B. Nielsen and I. McCulloch, Prog. Polym. Sci., 2013,
38, 2053-2069.
18 A. M. Glaudell, J. E. Cochran, S. N. Patel and M. L.
Chabinyc, Adv. Energy Mater., 2015, 5, 1401072.
19 H. Yang, T. J. Shin, Z. Bao and C. Y. Ryu, J. Polym. Sci.,
Part B: Polym. Phys., 2007, 45, 1303-1312.
43 G. Li, Y. Yao, H. Yang, V. Shrotriya, G. Yang and Y.
Yang, Adv. Funct. Mater., 2007, 17, 1636-1644.
44 J. Dou, Y. Zheng, T. Lei, S. Zhang, Z. Wang, W. Zhang, J.
Wang and J. Pei, Adv. Funct. Mater., 2014, 24, 6270-6278.
20 V. D. Mihailetchi, H. X. Xie, B. de Boer, L. J. A. Koster
10 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 2012

Page 11 of 12
Journal Name
RSC Advances
View ArticAle ROnTliInCeLE
DOI: 10.1039/C6RA05709H
45 S. Joshi, S. Grigorian, U. Pietsch, P. Pingel, A. Zen, D.
Neher and U. Scherf, Macromolecules, 2008, 41, 6800-
6808.
46 K. E. Aasmundtveit, E. J. Samuelsen, M. Guldstein, C.
Steinsland, O. Flornes, C. Fagermo, T. M. Seeberg, L. A. A.
Pettersson, O. Inganäs, R. Feidenhans'L and S. Ferrer,
Macromolecules, 2000, 33, 3120-3127.
47 T. Lei, Y. Cao, Y. Fan, C. Liu, S. Yuan and J. Pei, J. Am.
Chem. Soc., 2011, 133, 6099-6101.
48 R. Kim, P. S. K. Amegadze, I. Kang, H. Yun, Y. Noh, S.
Kwon and Y. Kim, Adv. Funct. Mater., 2013, 23, 5719-
5727.
49 H. Yang, S. W. LeFevre, C. Y. Ryu and Z. Bao, Appl.
Phys. Lett., 2007, 90, 172116.
50 D. H. Kim, B. Lee, H. Moon, H. M. Kang, E. J. Jeong, J.
Park, K. Han, S. Lee, B. W. Yoo, B. W. Koo, J. Y. Kim, W.
H. Lee, K. Cho, H. A. Becerril and Z. Bao, J. Am. Chem.
Soc., 2009, 131, 6124-6132.
51 H. Liao, C. Tsao, T. Lin, C. Chuang, C. Chen, U. Jeng, C.
Su, Y. Chen and W. Su, J. Am. Chem. Soc., 2011, 133,
13064-13073.
52 L. Liao, J. Bai, Y. Lin, Y. Qu, Y. Huang and X. Duan, Adv.
Mater., 2010, 22, 1941-1945.
53 C. Zhang, Y. Zang, E. Gann, C. R. McNeill, X. Zhu, C. Di
and D. Zhu, J. Am. Chem. Soc., 2014, 136, 16176-16184.
54 J. Huang, J. Pu, C. Hsu, M. Chiu, Z. Juang, Y. Chang, W.
Chang, Y. Iwasa, T. Takenobu and L. Li, ACS Nano, 2014,
8, 923-930.
55 S. Lee, B. J. Kim, H. Jang, S. C. Yoon, C. Lee, B. H. Hong,
J. A. Rogers, J. H. Cho and J. Ahn, Nano Lett., 2011, 11,
4642-4646.
56 B. J. Kim, S. Lee, M. S. Kang, J. Ahn and J. H. Cho, ACS
Nano, 2012, 6, 8646-8651.
57 X. Liang and S. Wi, ACS Nano, 2012, 6, 9700-9710.
58 G. Lee, Y. Yu, X. Cui, N. Petrone, C. Lee, M. S. Choi, D.
Lee, C. Lee, W. J. Yoo, K. Watanabe, T. Taniguchi, C.
Nuckolls, P. Kim and J. Hone, ACS Nano, 2013, 7, 7931-
7936.
59 X. Wang, F. Zhuang, R. Wang, X. Wang, X. Cao, J. Wang
and J. Pei, J. Am. Chem. Soc., 2014, 136, 3764-3767.
This journal is © The Royal Society of Chemistry 2012
J. Name., 2012, 00, 1-3 | 11

RSC Advances
Page 12 of 12
VJieowuArrtnicalelONnlainme e
ARTICLE
DOI: 10.1039/C6RA05709H
Table of Contents Graphic
A series of oligomers and polymers consisting of alternating thiophene and acetylene units (1-4 and PTE) were designed and synthesized via
Sonogashira reaction. And PTE was applied as the semiconductor to fabricate FETs with excellent performance. 2D-GIXRD was employed
to show the molecular edge-on orientation of PTE in the film.
12 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 2012