1
(trans-vinylene). H NMR (400 MHz, CDCl , d/ppm): 7.81–7.33
chromatography using a petroleum ether–dichloromethane
mixture (4/1 by volume) as eluent to afford a yellow solid (0.39 g,
3
(br, 7H), 6.85 (br, 12H), 4.04 (br, 4H), 2.52 (br, 2H), 2.13–1.95
ꢀ
1
1
6
3.1%). FT-IR (KBr, cm ): 931 (trans-vinylene). H NMR
400 MHz, CDCl
, d/ppm): 7.13–7.11 (d, 2H, J ¼ 8.28 Hz), 7.00
s, 1H), 6.89–6.87 (d, 4H, J ¼ 7.84 Hz), 6.82–6.77 (m, 6H), 6.64
(br, 6H), 1.49–0.65 (br, 56H). M ¼ 15 000, PDI ¼ 1.78.
w
(
(
(
3
1
3
s, 2H), 2.13 (s, 6H). C NMR (100 MHz, CDCl
3
, d/ppm):
48.36, 144.92, 139.55, 132.99, 131.06, 129.97, 129.54, 127.41,
24.96, 121.96, 117.79, 111.68, 108.97, 20.85. MALDI-TOF MS
NS) m/z: calcd for 539.000, found 539.110.
General instrumentation
1
1
1
13
H NMR and C NMR spectra were recorded with Bruker
(
C
26
H21Br
2
AVANCE 400 spectrometer. UV-vis spectra and photo-
luminescence (PL) spectra of the copolymers were obtained on
Perkin-Elmer Lamada 25 spectrometer and Perkin-Elmer LS-50
luminescence spectrometer, respectively. FT-IR spectra were
measured on Perkin-Elmer Spectra One. Molecular mass was
determined by matrix assisted laser desorption-ionization time-
of-flight mass spectrometry (MALDI-TOF MS) using a Bruker
Aupoflex-III mass spectrometer. The average molecular weight
and polydispersity index (PDI) of the copolymers were deter-
mined using Waters 1515 gel permeation chromatography (GPC)
analysis with THF as the eluent and polystyrene as the standard.
Thermal analyses were performed on a Netzsch TG 209 analyzer
Synthesis of M3. By following the similar method as for M1,
M3 was synthesized from compound 5 (0.4 g, 0.52 mmol) and
compound 6 (0.204 g, 0.52 mmol) and potassium tertbutoxide
(
0.1 g, 0.88 mmol). The crude product was purified on silica gel
chromatography using a petroleum ether–dichloromethane
mixture (3/1 by volume) as eluent to afford a dark purple solid
ꢀ
1
1
0.39 g, 75%). FT-IR (KBr, cm ): 930 (trans-vinylene). H
(
3
NMR (400 MHz, CDCl , d/ppm): 8.15 (s, 1H), 8.08 (s, 1H), 7.98–
7
7
.96 (m, 2H), 7.47–7.45 (d, 2H, J ¼ 8.32 Hz), 7.32 (s, 2H), 7.23–
.16 (m, 10H), 7.01–6.97 (d, 1H, J ¼ 16.00 Hz), 2.88–2.84 (t, 4H,
J ¼ 7.38 Hz), 2.45 (s, 6H), 1.83–1.82 (m, 4H), 1.48–1.38 (m, 12H),
2
and TA DSCQ10 instrument under N atmosphere with a
1
.03–1.01 (m, 6H). C NMR (100 MHz, CDCl , d/ppm): 152.65,
3
ꢁ
ꢀ1
1
1
1
1
1
1
1
3
heating and cooling rate of 20 C min . Cyclic voltammetry
47.76, 145.08, 143.44, 140.08, 139.30, 139.24, 137.55, 136.81,
36.39, 132.95, 130.60, 130.40, 130.01, 129.73, 127.28, 127.16,
26.15, 125.65, 125.03, 124.89, 122.53, 121.78, 119.36, 111.95,
09.74, 31.77, 31.07, 29.32, 29.21, 29.08, 28.71, 22.69, 20.89,
(
(
CV) was conducted on an electrochemistry workstation
CHI660A, Chenhua Shanghai) with the polymer film on a Pt
plate as the working electrode, Pt slice as the counter electrode,
and saturated calomel electrode (SCE) as the reference electrode
in a 0.1 M tetra-n-butylammonium hexafluorophosphate aceto-
4.16. MALDI-TOF MS (C52
005.130, found 1005.095.
2 3 4
H51Br N S ) m/z: calcd for
ꢀ
1
.
nitrile solution at a scan rate of 50 mV s
Synthesis of PT-TPA. To a 50 mL three-neck round bottom
flask, M1 (0.081 g, 0.15 mmol), M4 (0.115 g, 0.15 mmol) and
5 mL of anhydrous toluene were added. The mixture was
deoxygenated with nitrogen for 15 min. Pd(PPh ) (50 mg, 33.75
Fabrication of polymer field-effect transistor devices (FETs)
1
3
4
Polymer-based FETs were fabricated on highly doped silicon
mmol) was added under nitrogen and the mixture was again
flushed with nitrogen for 30 min. Then the reaction mixture was
wafers with a 300 nm SiO insulator, which was used as gate
2
electrode. The source–drain gold electrodes (30 nm) were
prepared by photolithography with the channel length (L) and
width (W) of 3 mm and 1400 mm, respectively. The substrates
were then subjected to cleaning using ultrasonication in acetone,
deionized water, and ethanol. Next, octadecyltrichlorosilane
ꢁ
stirred at 100 C for 3 days under nitrogen atmosphere. After
cooling to room temperature, the mixture was slowly poured into
methanol (150 mL). The precipitate was collected by filtration and
then purified by washing with methanol, hexane and chloroform
in a Soxhlet extractor for 24 h in sequence. The dark orange
copolymer was recovered from the chloroform fraction by rotary
(
2
OTS) treatment was performed on the surface of SiO gate
dielectrics in a vacuum to form an OTS self-assembled mono-
layer. To reduce the contact resistance, the gold drain–source
electrodes were modified with pentafluorothiophenol according
ꢀ
1
evaporation. Yield: 52 mg (32.5%). FT-IR (KBr, cm ): 958
1
trans-vinylene). H NMR (400 MHz, CDCl
(
3
, d/ppm): 7.55–7.37
(
br, 3H), 7.07–7.02 (br, 12H), 4.21 (br, 4H), 2.32–2.29 (br, 6H),
14
to the reported methods. Then, a layer of polymer semi-
1
.82–1.26 (br, 20H), 1.00–0.98 (br, 12H). M ¼ 9500, PDI ¼ 1.57.
w
conductor film (ꢂ40 nm) was deposited on the OTS-modified
substrates by spin-coating from a polymer solution in chloro-
ꢀ1
Synthesis of PT-DTBTTPA. To a 50 mL three-neck round
form (10 mg mL ) at a speed of 2000 rpm for 40 s. For further
bottom flask, M3 (150 mg, 0.15 mmol), M4 (115 mg, 0.15 mmol)
annealing of the polymer films, the samples were placed on a
ꢁ
and 15 mL of anhydrous toluene were added. The mixture was
hotplate at 160 C in air for 5 minutes before cooling down to
3 4
deoxygenated with nitrogen for 15 min. Pd(PPh ) (50 mg, 33.75
room temperature. Field-effect characteristics of the devices were
determined in air by using a Keithley 4200 SCS semiconductor
parameter analyzer. The field-effect mobility in saturation (m) is
calculated from the equation:
mmol) was added under nitrogen and the mixture was again
flushed with nitrogen for 30 min. Then the reaction mixture was
ꢁ
stirred at 100 C for 3 days under nitrogen atmosphere. After
cooling to room temperature, the mixture was slowly poured into
methanol (150 mL). The precipitate was collected by filtration
and then purified by washing with methanol, hexane and chlo-
roform in a Soxhlet extractor for 24 h in sequence. The purple
copolymer was recovered from the chloroform fraction by rotary
2
I
DS ¼ (W/2L)C
i
m(VGS ꢀ Vth
)
where W/L is the channel width/length, C is the insulator
i
capacitance per unit area, and VGS and Vth are the gate voltage
ꢀ
1
evaporation. Yield: 114 mg (49.8%). FT-IR (KBr, cm ): 944
and threshold voltage, respectively.
This journal is ª The Royal Society of Chemistry 2012
J. Mater. Chem., 2012, 22, 22913–22921 | 22915