Novel organic semiconductors based on phenyl and phenylthienyl derivatives for organic thin-film transistors

Article abstract of DOI:10.1166/jnn.2016.10748

New phenyl and phenylthienyl derivatives end-functionalized with carbazole and α-carboline, 9-(4- (9H-carbazol-9-yl)phenyl)-9H-carbazole, 9-(4-(9H-carbazol-9-yl)phenyl)-9H-pyrido[2,3-b]indole, 9- (3-(9H-carbazol-9-yl)phenyl)-9H-carbazole, 9-(3-(9H-carbazol-9-yl)phenyl)-9H-pyrido[2,3-b]indole, 9-(4-(5-(9H-carbazol-9-yl)thiophen-2-yl)phenyl)-9H-carbazole, and 9-(3-(5-(9H-carbazol-9-yl) thiophen-2-yl)phenyl)-9H-carbazole were synthesized and characterized as organic semiconductors for organic thin-film transistors (OTFTs). Most compounds exhibited p-channel characteristics with carrier mobility as high as 1.7 × 10^-5 cm²/Vs and a current on/off ratio of 10²-10⁴ for top-contact/bottom-gate OTFT devices.

Full text of DOI:10.1166/jnn.2016.10748

Article
Journal of
Nanoscience and Nanotechnology
Vol. 16, 910–919, 2016
Copyright © 2016 American Scientific Publishers
All rights reserved
www.aspbs.com/jnn
Printed in the United States of America
Novel Organic Semiconductors Based on
Phenyl and Phenylthienyl Derivatives for
Organic Thin-Film Transistors
Eunsoo Lee1ꢀ†, Bodakuntla Thirupathaiah2ꢀ†, Jaeuk Han1, Dahae Jung1, Guhyun Kwon1,
Choongik Kim1ꢀ∗, and SungYong Seo2ꢀ∗
1Department of Chemical and Biomolecular Engineering, Sogang University, Seoul 121-742, Korea
2Department of Chemistry, Pukyong National University, Busan 608-737, Korea
New phenyl and phenylthienyl derivatives end-functionalized with carbazole and ꢀ-carboline, 9-(4-
(9H-carbazol-9-yl)phenyl)-9H-carbazole, 9-(4-(9H-carbazol-9-yl)phenyl)-9H-pyrido[2,3-b]indole, 9-
(3-(9H-carbazol-9-yl)phenyl)-9H-carbazole, 9-(3-(9H-carbazol-9-yl)phenyl)-9H-pyrido[2,3-b]indole,
9-(4-(5-(9H-carbazol-9-yl)thiophen-2-yl)phenyl)-9H-carbazole,
and
9-(3-(5-(9H-carbazol-9-yl)
thiophen-2-yl)phenyl)-9H-carbazole were synthesized and characterized as organic semiconduc-
tors for organic thin-film transistors (OTFTs). Most compounds exhibited p-channel characteristics
with carrier mobility as high as 1ꢁ7 × 10−5 cm2/Vs and a current on/off ratio of 102–104 for
Delivered by Publishing Technology to: McMaster University
top-contact/bottom-gate OTFT devices.
IP: 179.106.152.75 On: Tue, 12 Jan 2016 10:03:25
Keywords: Organic Thin-Film Transistors, Organic Semiconductor, Phenylthiophene, Carbazole,
Copyright: American Scientific Publishers
ꢀ-Carboline.
1. INTRODUCTION
ꢁ-carboline moieties have extensively been studied as host
materials for phosphorescent organic light-emitting diodes
(PHOLEDs),17–20 they have hardly been employed for
OTFTs.21
Organic electronic devices have gained considerable inter-
est due to their potential applications as low-cost, solution-
processable, flexible electronics.1ꢀ2 Among them, organic
thin-film transistors (OTFTs) are representative examples
employed for most modern electronics.3ꢀ4 To this end,
there have been extensive efforts to develop and opti-
mize basic OTFT components—semiconductor, dielectric,
and contacts. Among previously developed OTFT semi-
conductors, pentacene,5–7 oligothiophene,8ꢀ9 and anthra-
dithiophene derivatives10 are representative examples with
high carrier mobility. There is still a need to develop
and optimize novel organic semiconductors with high
electrical performance and ambient stability via con-
trolling their chemical structure, molecular interaction,
and the resulting film microstructure/morphology.11–16
Carbazole and ꢁ-carboline are aromatic heterocyclic
organic compounds which contain indole structure fused
with benzene and pyridine ring structure, respectively.
Although organic semiconductors based on carbazole and
To this end, we have synthesized six organic semicon-
ductors based on phenyl and phenylthienyl cores function-
alized with carbazole and ꢁ-carboline moieties (Fig. 1).
As shown, chemical structures of organic semiconduc-
tors were varied by linking carbazoles or carbazole/ꢁ-
carboline groups with phenyl and phenylthienyl moieties.
New compounds were characterized by thermogravimetric
analysis (TGA), differential scanning calorimetry (DSC),
UV-vis spectroscopy, and cyclic voltammetry to obtain
thermal, optical, and electrochemical data. Density func-
tional theory (DFT) calculations were performed to deter-
mine HOMO/LUMO energy levels as well as molecular
structure of each compound. Furthermore, the semicon-
ductor films were employed as an active layer via vac-
uum deposition in a top-contact/bottom-gate OTFT and the
resulting devices were characterized. Finally, the morphol-
ogy and microstructure of the semiconducting films were
investigated by atomic force microscopy (AFM) and X-ray
diffraction (XRD) to correlate these properties with device
∗Authors to whom correspondence should be addressed.
†These two authors contributed equally to this work.
910
J. Nanosci. Nanotechnol. 2016, Vol. 16, No. 1
1533-4880/2016/16/910/010
doi:10.1166/jnn.2016.10748

Lee et al.
Novel Organic Semiconductors Based on Phenyl and Phenylthienyl Derivatives for Organic Thin-Film Transistors
2.2. Synthesis
2.2.1. Synthesis of 9-(3-iodophenyl)-9H-Carbazole and
N
N
N
N
9-(3-(9H-carbazol-9-yl) phenyl)-9H-Carbazole (1)
9H-Carbazole (3.5 g, 20.9 mmol), 1,3-diiodobenzene
(10.3 g, 31.4 mmol), CuI (1.2 g, 6.3 mmol), K2CO3 (11.4 g,
83.7 mmol), and 18-crown-6 ether (2.8 g, 10.5 mmol)
were dissolved in 150 mL of o-dichlorobenzene (DCB)
and the reaction mixture was allowed to reflux under
a nitrogen atmosphere for 35 h. Then solvent was dis-
tilled under vacuo. The crude mixture was diluted with
CH2Cl2, filtered, and then the residue was washed with
CH2Cl2. The combined filtrates were washed with dis-
tilled H2O. The organic layer was dried on anhydrous
MgSO4 and evaporated in vacuo to give the crude prod-
uct. Then the crude product was purified by flash column
chromatography on silica gel to give 9-(3-iodophenyl)-9H-
carbazole (3.62 g, 46.9%) and compound 1 (600 mg, 7.0%).
Spectral data matched well with values reported in the
literature.19ꢀ22ꢀ23 9-(3-Iodophenyl)-9H-carbazole: 1H NMR
(400 MHz, CDCl3ꢅ: ꢄ 8.14 (d, 7.7 Hz, 2 H), 7.94 (t, 1.4 Hz,
1 H), 7.81 (dt, 1.4, 8.0 Hz, 1 H), 7.57 (ddd, 1.1, 2.2, 8.0 Hz,
1 H), 7.38–7.43 (m, 4 H), 7.29–7.36 (m, 3 H). Compound
N
1
2
N
N
N
N
N
3
4
S
N
N
N
S
N
5
6
Figure 1. Chemical structures of the phenyl and phenylthienyl deriva-
tives employed in this study.
performance. Our results revealed that most devices were
active as p-channel OTFTs with carrier mobility as high
as 1ꢂ7 ×10−5 cm2/Vs and current on/off ratio of ∼104.
1
1: H NMR (400 MHz, CDCl3ꢅ: ꢄ 8.17 (d, 7.7 Hz, 4 H),
7.86 (t, 8.0 Hz, 1 H), 7.84 (d, 1.1 Hz, 1 H), 7.72 (dd,
1.8, 8.0 Hz, 2 H), 7.56 (d, 8.0 Hz, 4 H), 7.46 (t, 8.0 Hz,
Delivered by Publishing Technology to: McMaster University
4 H), 7.33 (t, 7.7 Hz, 4 H). 13C NMR (100 MHz, CDCl3ꢅ:
2. EXPERIMENTAL DETAILS
2.1. General Methods
IP: 179.106.152.75 On: Tue, 12 Jan 2016 10:03:25
ꢄ 140.5, 139.3, 131.1, 126.1, 125.7, 125.2, 123.5, 120.4,
Copyright: American Scientific Publishers
120.2, 109.6.
Air and/or moisture sensitive reactions were carried out
under an argon atmosphere in oven-dried glassware and
with anhydrous solvents. All compounds were purchased
from commercial sources unless otherwise noted and used
without further purification. Solvents were freshly distilled
(1,4-dioxane and toluene over sodium) or dried by pass-
ing through an alumina column. Thin layer chromatog-
raphy was carried out on glass plates coated with silica
gel SiO2 60 F254 from Merck; visualization with a UV
lamp (254 nm) or by staining with a p-anisaldehyde or
potassium permanganate solution. Flash chromatography
was performed with silica gel SiO2 60 (0.040–0.063 ꢃm,
230–400 mesh), technical solvents, and a head pressure of
0.2–0.4 bar. Proton (1H) and carbon (13C) nuclear mag-
netic resonance (NMR) spectroscopy was performed on
a JEOL ECP-400 spectrometer at 400 MHz (1H) and
100 MHz (13C) at 294 K. Chemical shifts are reported
in ppm relative to the residual protiated solvent (CDCl3:
ꢄH = 7ꢂ26 ppm, ꢄC = 77ꢂ16 ppm). All 13C NMR spec-
tra are proton decoupled. The resonance multiplicity is
described as s (singlet), d (doublet), t (triplet), q (quartet),
p (pentet), dd (doublet of doublet), dt (doublet of triplet),
td (triplet of doublet), m (multiplet), and br (broad). High-
resolution mass spectrometry (HRMS) was measured on a
JEOL JMS-700 spectrometer. Mass peaks are reported in
m/z units.
2.2.2. Synthesis of 9-(3-(9H-carbazol-9-yl)phenyl)-9H-
Pyrido[2,3-b] Indole (2)
9-(3-Iodophenyl)-9H-carbazole (300 mg, 0.81 mmol),
ꢁ-carboline (150.3 mg, 0.89 mmol), CuI (46.3 mg,
0.24 mmol), K3PO4 (343.9 mg, 1.62 mmol), and trans-1,2-
diaminocyclohexane (29.2 ꢃL, 0.24 mmol) were dissolved
in 10 mL of 1,4-dioxane under a nitrogen atmosphere.
The reaction mixture was refluxed for 20 h and the reac-
tion mixture was filtered and the residue was washed with
CH2Cl2. The combined filtrates were washed with dis-
tilled water. The organic layer was dried on anhydrous
MgSO4 and evaporated in vacuo to give the crude prod-
uct. Then the crude product was purified by flash col-
umn chromatography on silica gel to give compound 219
1
(147.4 mg, 44.4%). H NMR (400 MHz, CDCl3ꢅ: ꢄ 8.54
(dd, 1.4, 5.1 Hz, 1 H), 8.40 (dd, 1.4, 7.7 Hz, 1 H), 8.15
(dd, 5.1, 7.7 Hz, 3 H), 7.97 (bt, 1.4 Hz, 1 H), 7.80–
7.87 (m, 2 H), 7.65–7.72 (m, 4 H), 7.51 (dt, 1.1, 8.0 Hz,
1 H), 7.45 (dt, 1.1, 8.0 Hz, 2 H), 7.26–7.38 (m, 4 H).
13C NMR (100 MHz, CDCl3ꢅ: ꢄ 151.7, 146.4, 140.5,
139.5, 138.8, 137.7, 130.7, 128.3, 127.1, 126.0, 125.6,
125.5, 124.4, 123.5, 121.0, 120.3, 120.1, 116.4, 110.3,
109.8.
J. Nanosci. Nanotechnol. 16, 910–919, 2016
911

Novel Organic Semiconductors Based on Phenyl and Phenylthienyl Derivatives for Organic Thin-Film Transistors
Lee et al.
2.2.3. Synthesis of 9-(4-bromophenyl)-9H-Carbazole
9H-Carbazole (5.02 g, 30 mmol), 1,4-dibromobenzene
(14.15 g, 60 mmol), CuI (5.71 g, 30 mmol), K2CO3
(16.59 g, 120 mmol), and 18-crown-6 ether (3.96 g,
15 mmol) were dissolved in 100 mL of N ,N -
dimethylacetamide (DMA) and the reaction mixture was
allowed to reflux under a nitrogen atmosphere for 45 h.
Then N ꢀN -dimethylacetamide was distilled under vacuo.
The crude mixture was diluted with CH2Cl2, filtered,
and the residue was washed with CH2Cl2. The combined
filtrates were washed with distilled H2O. The organic
layer was dried on anhydrous MgSO4 and evaporated in
vacuo to give the crude product. Then the crude prod-
uct was purified by flash column chromatography on sil-
ica gel to give 9-(4-bromophenyl)-9H-carbazole (6.53 g,
67.5%). Spectral data matched well with values reported
in the literature.241H NMR (400 MHz, CDCl3ꢅ: ꢄ 8.17 (d,
7.7 Hz, 2 H), 7.72 (d, 8.8 Hz, 2 H), 7.38–7.48 (m, 6 H),
7.30–7.34 (m, 2 H).
13.9% , brsm 20.8%). 1H NMR (400 MHz, CDCl3ꢅ: ꢄ 8.56
(dd, 1.4, 4.7 Hz, 1 H), 8.44 (dd, 1.4, 7.7 Hz, 1 H), 8.18
(d, 7.7 Hz, 3 H), 7.94 (d, 8.4 Hz, 2 H), 7.84 (d, 8.4 Hz,
2 H), 7.67 (d, 8.4 Hz, 1 H), 7.60 (d, 8.0 Hz, 2 H), 7.55
(dt, 1.1, 8.0 Hz, 1 H), 7.47 (dt, 1.1, 8.0 Hz, 2 H), 7.40
(t, 8.0 Hz, 1 H) 7.29–7.35 (m, 3 H). 13C NMR (100 MHz,
CDCl3ꢅ: ꢄ 151.7, 146.4, 140.7, 139.8, 136.7, 135.1, 128.5,
128.4, 128.0, 127.1, 126.0, 123.5, 121.1, 121.0, 120.3,
120.1, 116.5, 116.4, 110.4, 109.8. HRMS-EI(m/z): [M+]
calcd for C29H19N3, 409.1579; found, 409.1576.
2.2.6. Synthesis of 4,4,5,5-Tetramethyl-2-(thiophen-2-
yl)-1,3,2-Dioxaborolane
n-BuLi (41.18 mL, 65.9 mmol, 1.6 M in hexane) was
added drop wise to the stirred solution of thiophene (5.04 g,
ꢀ
59.9 mmol) in 50 mL of THF at −78 C. Then the solu-
tion was stirred for 30 min at room temperature. After
cooling to −78 ꢀC, 2-isopropoxy-4,4,5,5-tetramethyl-1,3,2-
dioxaborolane (11.14 g, 59.9 mmol) in 80 mL of THF
was added and the reaction mixture was allowed to stir
for 30 min at room temperature. After completion of the
reaction (indicated by TLC), solvent was removed under
vacuum and the residue was taken up in CHCl3. Aqueous
5 N HCl (50 mL) was added under vigorous stirring for
30 min. The organic layer was collected and dried over
MgSO4. After evaporation of the solvent the product was
recrystallized from pentane (10.78 g, 86.0%). Spectral data
2.2.4. Synthesis of 9-(4-(9H-carbazol-
9-yl)phenyl)-9H-Carbazole (3)
9-(4-Bromophenyl)-9H-carbazole (300 mg, 0.93 mmol),
9H-carbazole (186.8 mg, 1.11 mmol), CuI (53.2 mg,
0.28 mmol), K2CO3 (506 mg, 3.72 mmol), and 18-crown-6
ether (123 mg, 0.47 mmol) were dissolved in 10 mL of
N ꢀN -dimethylacetamide (DMA) and the reaction mixture
Delivered by Publishing Technology to: McMaster University
matched well with values reported in the literature.261
H
IP: 179.106.152.75 On: Tue, 12 Jan 2016 10:03:25
was allowed to reflux under a nitrogen atmosphere for
Copyright: American Scientific Publishers
NMR (400 MHz, CDCl3ꢅ: ꢄ 7.65(d, 3.6 Hz, 1 H), 7.63 (d,
4.6 Hz, 1 H), 7.20 (dd, 4.7, 3.6 Hz, 1 H), 1.34 (s, 12 H).
24 h. The reaction mixture was allowed to cool to room
temperature. Then the crude mixture was filtered, and the
residue was washed with CH2Cl2. The combined filtrates
were evaporated to dryness under reduced pressure. The
crude product was purified by flash column chromatogra-
phy on silica gel to give compound 3 (35 mg, 9.2%, brsm
15.6%). Spectral data matched well with values reported
in the literature.251H NMR (400 MHz, CDCl3ꢅ: ꢄ 8.20 (d,
8.0 Hz, 4 H), 7.83 (s, 4 H), 7.58 (d, 8.0 Hz, 4 H), 7.49
(dt, 1.1, 8.4 Hz, 4 H), 7.35 (dt, 1.1, 8.4 Hz, 4 H). 13C
NMR (100 MHz, CDCl3ꢅ: ꢄ 140.7, 136.6, 128.3, 126.1,
123.5, 120.4, 120.2, 109.7.
2.2.7. Synthesis of 2-(4-bromophenyl) Thiophene
A mixture of 1-bromo-4-iodobenzene (2.0 g, 7.07 mmol),
4,4,5,5-tetramethyl-2-(thiophen-2-yl)-1,3,2-dioxaborolane
(2.97 g, 14.1 mmol), Pd(PPh3ꢅ4 (408 mg, 0.35 mmol), and
Na2CO3 (1.49 g, 14.1 mmol) were dissolved in toluene
(40 mL), THF (15 mL), and H2O (15 mL) and the reaction
mixture was refluxed for 5 h. After completion of the
reaction (indicated by TLC), the solvent was removed
under vacuum, H2O (30 mL) and CH2Cl2 (40 mL) were
added. The organic layer was separated and dried on
anhydrous MgSO4. The solvent was removed under
reduced pressure. Then the crude product was purified by
flash column chromatography on silica gel to give 2-(4-
bromophenyl) thiophene (1.26 g, 74.6%). Spectral data
2.2.5. Synthesis of 9-(4-(9H-carbazol-9-yl)
phenyl)-9H-Pyrido [2, 3-b] Indole (4)
9-(4-Bromophenyl)-9H-carbazole (300 mg, 0.93 mmol),
ꢁ-carboline (187.7 mg, 1.12 mmol), CuI (53.2 mg,
0.28 mmol), K2CO3 (506.6 mg, 3.72 mmol), and 18-
crown-6 ether (24.6 mg, 0.092 mmol) were dissolved in
10 mL of N ꢀN -dimethylacetamide (DMA) and the reac-
tion mixture was allowed to reflux under a nitrogen atmo-
sphere for 24 h. The reaction mixture was allowed to cool
to room temperature. Then the crude mixture was filtered,
and the residue was washed with CH2Cl2. The combined
filtrates were evaporated to dryness under reduced pres-
sure. The crude product was purified by flash column chro-
matography on silica gel to give compound 4 (53 mg,
matched well with values reported in the literature.271
H
NMR (400 MHz, CDCl3ꢅ: ꢄ 7.48 (d, 3.6 Hz, 4 H), 7.29
(d, 4.4 Hz, 2 H), 7.07 (dt, 1.4, 4.4 Hz, 1 H).
2.2.8. Synthesis of 2-(3-bromophenyl) Thiophene
A mixture of 1,3-dibromobenzene (2.0 g, 8.47 mmol),
4,4,5,5-tetramethyl-2-(thiophen-2-yl)-1,3,2-dioxaborolane
(2.67 g, 12.7 mmol), Pd(PPh3ꢅ4 (489 mg, 0.42 mmol), and
Na2CO3 (1.79 g, 16.9 mmol) were dissolved in toluene
(50 mL), THF (15 mL), and H2O (15 mL) and the reaction
912
J. Nanosci. Nanotechnol. 16, 910–919, 2016

Lee et al.
Novel Organic Semiconductors Based on Phenyl and Phenylthienyl Derivatives for Organic Thin-Film Transistors
mixture was refluxed for 2.5 h. After completion of the
reaction (indicated by TLC), the solvent was removed
under vacuum, H2O (30 mL) and CH2Cl2 (50 mL) were
added. The organic layer was separated and dried on
MgSO4. The solvent was removed under reduced pressure.
Then the crude product was purified by flash column
chromatography on silica gel to give 2-(3-bromophenyl)
thiophene (1.58 g, 77.9%). Spectral data matched well
with values reported in the literature.281H NMR (400 MHz,
CDCl3ꢅ: ꢄ 7.76 (t, 1.8 Hz, 1 H), 7.53 (td, 1.1, 7.7 Hz,
1 H), 7.40 (td, 1.1, 8.4 Hz, 1 H), 7.31 (d, 4.4 Hz, 2 H),
7.24 (t, 7.7 Hz, 1 H), 7.09 (t, 4.4 Hz, 1 H).
removed under reduced pressure. Then the crude product
was purified by flash column chromatography on silica gel
to give 2-bromo-5-(3-bromophenyl) thiophene (653 mg,
65.9%). Spectral data matched well with values reported
in the literature.291H NMR (400 MHz, CDCl3ꢅ: ꢄ 7.65 (t,
1.8 Hz, 1 H), 7.42 (dd, 1.4, 7.7 Hz, 2 H), 7.23 (t, 7.7 Hz,
1 H), 7.04 (d, 2.5 Hz, 2 H). 13C NMR (100 MHz, CDCl3ꢅ:
ꢄ 143.9, 135.5, 130.9, 130.7, 130.4, 128.4, 124.1, 124.0,
123.0, 112.3.
2.2.11. Synthesis of 9-(4-(5-(9H-carbazol-9-yl)
thiophen-2-yl) phenyl)-9H-Carbazole (5)
2-Bromo-5-(4-bromophenyl)
thiophene
(100
mg,
0.31 mmol), 9H-carbazole (120.9 mg, 0.72 mmol), CuI
(17.9 mg, 0.094 mmol), K3PO4 (133 mg, 0.63 mmol),
and trans-1,2-diaminocyclohexane (11.2 ꢃL, 0.094 mmol)
were dissolved in 10 mL of 1,4-dioxane under a nitrogen
atmosphere. The reaction mixture was refluxed for 24 h.
Then the reaction mixture was filtered and the residue
was washed with CH2Cl2. The combined filtrates were
washed with distilled water. The organic layer was dried
on anhydrous MgSO4 and evaporated in vacuo to give the
crude product. Then the crude product was purified by
flash column chromatography on silica gel to give com-
2.2.9. Synthesis of 2-Bromo-5-(4-bromophenyl)
Thiophene
N -Bromosuccinimide (1.87 g, 10.5 mmol) was added in
small portions to the solution of 2-(4-bromophenyl) thio-
phene (1.26 g, 5.27 mmol) in anhydrous THF (40 mL)
at room temperature under a nitrogen atmosphere. The
reaction mixture was allowed to stir at room temperature
under for 2.5 h. After completion of the reaction (indi-
cated by TLC), H2O (30 mL) and Et2O (60 mL) were
added. The organic layer was separated and dried on anhy-
drous MgSO4. The solvent was removed under reduced
pressure. Then the crude product was purified by flash
column chromatography on silica gel to give 2-bromo-5-
(4-bromophenyl) thiophene (1.67 g, 99.7%). Spectral data
1
pound 5 (100 mg, 64.9%). H NMR (400 MHz, CDCl3ꢅ:
ꢄ 8.16 (dd, 7.7, 13.5 Hz, 4 H), 7.88 (d, 8.4 Hz, 2 H), 7.64
(d, 8.4 Hz, 2 H), 7.60 (d, 8.4 Hz, 2 H), 7.42–7.51 (m,
13
Delivered by Publishing Technology to: McMaster University
8 H), 7.30–7.36 (m, 4 H). C NMR (100 MHz, CDCl3ꢅ:
IP: 179.106.152.752O91n: Tue, 12 Jan 2016 10:03:25
matched well with values reported in the literature.
NMR (400 MHz, CDCl3ꢅ: ꢄ 7.49 (d, 8.4 Hz, 2 H), 7.36
(d, 8.4 Hz, 2 H), 7.03 (s, 2 H).
H
ꢄ 141.8, 141.5, 140.6, 138.2, 137.2, 133.0, 127.5, 127.0,
Copyright: American Scientific Publishers
126.3, 126.0, 125.9, 123.6, 123.4, 122.3, 120.7, 120.3,
120.2, 120.1, 110.2, 109.7. HRMS-EI(m/z): [M+] calcd
for C34H22N2S, 490.1504; found, 490.1507.
2.2.10. Synthesis of 2-Bromo-5-(3-bromophenyl)
Thiophene
2.2.12. Synthesis of 9-(3-(5-(9H-carbazol-9-yl)
thiophen-2-yl) phenyl)-9H-Carbazole (6)
N -Bromosuccinimide (2.23 g, 12.5 mmol) was added in
small portions to the solution of 2-(3-bromophenyl) thio-
phene (1.50 g, 6.27 mmol) in 40 mL of anhydrous THF at
room temperature under a nitrogen atmosphere. The reac-
tion mixture was allowed to stir at room temperature for
2.5 h. After completion of the reaction (indicated by TLC),
H2O (30 mL) and Et2O (60 mL) were added. The organic
layer was separated and dried on MgSO4. The solvent was
2-Bromo-5-(3-bromophenyl)
thiophene
(200
mg,
0.63 mmol), 9H-carbazole (242 mg, 1.38 mmol), CuI
(36.0 mg, 0.19 mmol), K3PO4 (266 mg, 1.25 mmol),
and trans-1,2-diaminocyclohexane (22.6 ꢃL, 0.19 mmol)
were dissolved in 15 mL of 1,4-dioxane under a nitrogen
atmosphere. The reaction mixture was refluxed for 16 h.
Then the reaction mixture was filtered and the residue
N
N
I
1
+
CuI, K2CO3
18-crown-6
+
NH
I
DCB, reflux, 35 h
I
CuI, K3PO4
N
N
+
NH
N
trans -1,2 diaminocyclohexane
1,4-Dioxane reflux, 20 h
N
N
2
Scheme 1. Synthesis of compounds 1 and 2.
J. Nanosci. Nanotechnol. 16, 910–919, 2016
913

Novel Organic Semiconductors Based on Phenyl and Phenylthienyl Derivatives for Organic Thin-Film Transistors
Lee et al.
N
N
NH
CuI, K2CO
3
CuI, K2CO3
3
+
+
NH Br
Br
N
Br
18-crown-6
DMA, reflux, 24 h
18-crown-6
DMA, reflux, 45 h
N
N
NH
N
N
4
Scheme 2. Synthesis of compounds 3 and 4.
was washed with CH2Cl2. The combined filtrates were
washed with distilled water. The organic layer was dried
on anhydrous MgSO4 and evaporated in vacuo to give
the crude product. Then the crude product was purified
by flash column chromatography on silica gel to give
compound 6 (135 mg, 43.8%). 1H NMR (400 MHz,
CDCl3ꢅ: ꢄ 8.18 (dd, 0.7, 8.0 Hz, 2 H), 8.12 (dd, 0.7,
8.0 Hz, 2 H), 7.88 (t, 2.2 Hz, 1 H), 7.72–7.75 (m, 1 H),
7.66 (t, 7.7 Hz, 1 H), 7.567 (t, 8.0 Hz, 3 H), 7.43–7.51
(m, 7 H), 7.30–7.35 (m, 4 H), 7.21 (d, 3.6 Hz, 1 H). 13C
NMR (100 MHz, CDCl3ꢅ: ꢄ 141.7, 141.2, 140.7, 140.5,
138.9, 130.5, 126.3, 126.1, 126.0, 125.8, 124.6, 124.1,
123.5, 123.4, 122.5, 120.7, 120.4, 120.3, 120.29, 120.22,
120.1, 110.2, 109.7, 109.6. HRMS-EI(m/z): [M+] calcd
the substrate was placed in a N2 filled closed chamber
with a few mL of ammonium hydroxide solution for vapor
annealing for 10 h at room temperature. The substrate was
then rinsed with DI water and toluene, resulting in aqueous
contact angle of 113ꢀ. Furthermore, two polymer buffer
layers including PS (Mn = 30 kg/mol) and PMMA (Mn =
25 kg/mol) were spin-coated onto the SiO2/Si substrate
(10 mg/mL in toluene, 5000 rpm), resulting in thickness
of ∼40 nm. The organic semiconductor thin films (70 nm)
were vacuum-deposited onto the substrates at 20 and 60 ꢀC
at a deposition rate of 0.4 Å s−1 under a pressure of 5 ×
10−6 Torr. Gold source/drain electrodes (40 nm) were ther-
mally evaporated through a shadow mask with a channel
Delivered by Publishing Technology to: McMaster University
length and width of 50 and 2000 ꢃm, respectively.
IP: 179.106.152.75 On: Tue, 12 Jan 2016 10:03:25
for C34H22N2S, 490.1504; found, 490.1503.
Copyright: American Scientific Publishers
2.5. Characterization
2.3. Theoretical Calculation
Thermogravimetric analyses (TGA, TA Instrument Q50-
1555) were performed on each sample in a platinum
Density functional theory (DFT) calculations on the
present semiconductors were performed using the B3LYP
(Becke’s 3 parameters employing the Lee-Yang-Parr) func-
tional and the 6-31G basis set as implemented in Gaussian
03W program.
ꢀ
crucible; the sample was heated from 40 to 700 C at
ꢀ
a heating rate of 10 C min−1, while the chamber was
purged continuously with N2 gas at a rate of 100 mL
min−1. Differential scanning calorimetry (DSC) analyses
(TA instrument Q20-2487) wereꢀperformed at a scan rate
of 10 K min−1 from 40 to 300 C. The UV-visible spec-
tra of the compounds in chloroform were obtained using
a JASCO V-660 spectrometer with quartz cuvette over
the special range 200–700 nm. Cyclic voltammetry (CV)
experiments were performed with a conventional three-
electrode configuration (glassy carbon working electrode,
platinum-wire counter electrode, and Ag/AgCl reference
electrode) with supporting electrolyte of tetrabutylam-
monium tetrafluoroborate in the specified dry solvent
on AUT302N Electrochemical Analyzer (Autolab). All
electrochemical potentials were referenced to an Fc+/Fc
internal standard. The current–voltage characteristics of
fabricated OTFT devices were measured at room temper-
ature under vacuum using a Keithley 4200 SCS. Carrier
mobilities (ꢃꢅ were calculated in the saturation regime.30
Film thicknesses were measured by profilometer (Dec-
tak XT). The surface morphology and film microstruc-
ture of thin films was characterized using an atomic
2.4. Device Fabrication
Top-contact/bottom-gate OTFTs were fabricated on a
heavily n-doped silicon (n++-Si) substrate with thermally
grown silicon dioxide (300 nm SiO2ꢅ as dielectric layer.
The SiO2/Si substrate was washed in an ultrasonic bath
using acetone for 10 min, dried using a nitrogen gun,
and cleaned by air plasma for 5 min (Harrick Plasma,
18 W). Various gate dielectric layers including two
self-assembled monolayers (hexamethyldisilazane; HMDS
and octadecyltrimethoxysilane; OTMS) and two polymer
(polystyrene; PS and polymethylmethacrylate; PMMA)
layers were applied onto the surface of the substrate. For
HMDS treatment, a few drops of HMDS were loaded
inside a self-assembly chamber under an N2 atmosphere
and the SiO2/Si substrates were exposed to this atmosphere
for 48 h to give a hydrophobic surface with aqueous con-
tact angle of 102ꢀ. For OTMS treatment, 3 mM solution of
OTMS in trichloroethylene was dropped on SiO2/Si sub-
strate and the substrate was spin-coated at 3000 rpm. Then,
914
J. Nanosci. Nanotechnol. 16, 910–919, 2016

Lee et al.
Novel Organic Semiconductors Based on Phenyl and Phenylthienyl Derivatives for Organic Thin-Film Transistors
Br
S
S
Br
I
Br
Br
Pd(PPh3)4, Na2CO3
NBS, THF
rt
O
NH
B
S
Br
S
Toluene/THF/H2O
reflux
S
O
Br
Br
Br
Br
S
N
N
CuI, K3PO4
5
6
trans -1,2 diaminocyclohexane
1,4-Dioxane, reflux
S
N
N
Scheme 3. Synthesis of compounds 5 and 6.
force microscope (AFM, NX10, Park Systems) and X-ray
diffraction (XRD, Miniflex, Rigaku), respectively.
treated with carbazole to afford compound 5. The syn-
thesis of compound 6 was exactly the same as that of
compound 5 except using 1,3-dibromobenzene instead of
1-bromo-4-iodobenzene as shown in Scheme 3.26–29
3. RESULTS AND DISCUSSION
3.1. Synthesis
Compounds 1 and 9-(3-iodophenyl)-9H-carbazole were
synthesized by an Ullmann coupling of 1,3-diiodobenzene
3.2. Thermal and Optical Properties
Delivered by Publishing Technology to: McMaster University
Thermal properties of the new phenyl and phenylthienyl
IP: 179.106.152.75 On: Tue, 12 Jan 2016 10:03:25
derivatives were characterized by thermogravimetric anal-
ysis (TGA) and differential scanning calorimetry (DSC).
Copyright: American Scientific Publishers
and carbazole according to the method reported in the
literature.19ꢀ22ꢀ23 Then 9-(3-iodophenyl)-9H-carbazole
was treated with ꢁ-carboline to afford compound 2
(Scheme 1). 9-(4-Bromophenyl)-9H-carbazole was syn-
thesized by an Ullmann coupling of 1,4-dibromobenzene
and carbazole according to the method reported in the
literature.24ꢀ25 Then 9-(4-bromophenyl)-9H-carbazole
was further reacted with carbazole and ꢁ-carboline to
give compounds 3 and 4 as shown in Scheme 2. Com-
pound 5 was synthesized through the following route.
First 1-bromo-4-iodobenzene was reacted with 4,4,5,5-
tetramethyl-2-(thiophen-2-yl)-1,3,2-dioxaborolane under
palladium catalyst via Suzuki coupling to give 2-(4-
bromophenyl) thiophene, then bromination was tried using
NBS. Finally, 2-bromo-5-(4-bromophenyl) thiophene was
ꢀ
Sharp endotherms above 162 C and weight loss (∼5%)
ꢀ
upon heating above 302 C were observed (Table I), indi-
cating thermal stability of the developed compounds in
this study. The optical absorption spectra of the com-
pounds 1–4 (phenyl derivatives) in chloroform solution
showed similar patterns with ꢆmax = 242, 293 nm for com-
pound 1, ꢆmax = 246, 293 nm for compound 2, ꢆmax
=
245, 293 nm for compound 3, and ꢆmax = 244, 294 nm
for compound 4, respectively (Fig. 2). Similarly, com-
pounds 5 and 6 (phenylthienyl derivatives) exhibited ꢆmax
s
at similar positions as shown in Figure 2 (at 241, 293,
339 nm for compound 5 and at 246, 292, 328 nm for
compound 6, respectively). Hence, the HOMO-LUMO
energy gaps calculated from the onset of the experimental
Table I. Physical and electrochemical properties of compounds 1–6.
peak
ox
DSC Tm (ꢀC)
TGA (ꢀC; 5%)
UV-Vis ꢆmax (nm)a
E
(V)b
Egap (eV)a
HOMO (eV)b
LUMO (eV)c
1
2
3
4
5
6
181
162
321
279
185
170
302
322
323
326
369
353
242, 293
246, 293
245, 293
244, 294
241, 293, 339
246, 292, 328
1.45
3.57
3.53
3.55
3.52
3.31
3.32
−5ꢂ55
−5ꢂ53
−5ꢂ42
−5ꢂ43
−5ꢂ33
−5ꢂ22
−1ꢂ98
−2ꢂ00
−1ꢂ87
−1ꢂ91
−2ꢂ02
−1ꢂ90
1.43
1.32
1.33
1.23
1.12
Notes: aMeasured by UV-vis spectroscopy; bMeasured by cyclic voltammetry in o-C6H4Cl2 at 25 ꢀC (using ferrocene/ferrocenium as internal standard at +0.7 V); cCalculated
as LUMO = HOMO + Egap
.
J. Nanosci. Nanotechnol. 16, 910–919, 2016
915

Novel Organic Semiconductors Based on Phenyl and Phenylthienyl Derivatives for Organic Thin-Film Transistors
Lee et al.
1.0
10–7
VDS = –100 V
1
2
3
4
5
6
0.8
0.6
0.4
0.2
0.0
10–9
10–11
10–13
200
300
400
500
Wavelength (nm)
–100
–50
0
Figure 2. Optical spectra of carbazole/ꢁ-carboline derivatives.
VG (V)
Figure 4. Representative device characteristic (transfer plot) of OTFT
device fabricated with thin films of compounds 5 on HMDS-treated SiO2
substrates (TD = 60 ꢀC).
optical absorption are ∼3.55 eV for compounds 1–4
and ∼3.30 eV for compounds 5 and 6. These results
might indicate that the compounds with longer molecu-
lar length (more chemical moieties) exhibit the greater
ꢇ-conjugation.
shifted to more negative values, compared to that of com-
pounds 1 and 2. Phenylthienyl derivatives compounds 5
and 6 exhibited the oxidation potentials shifted to more
negative values (Eox = +1.23 V and +1.12 V, respectively)
compared to compounds 1–4. Hence, HOMO energy lev-
els obtained by the conversion of oxidation potential using
3.3. Electrochemical Properties
Cyclic voltammetry (CV) measurements of the new com-
pounds were performed in o-C6H4Cl2 at 25 ꢀC. The
compounds 1 and 2 exhibited oxidation peaks at around
Delivered by Publishing Technology to: McMaster University
ferrocene as the standard were higher for compounds 5 and
6 (−5.33 and −5.22 eV, respectively), compared to com-
pounds 1–4(−5.55–−5.42 eV). The LUMO energy levels
for each compound were calculated from the HOMO (from
IP: 179.106.152.75 On: Tue, 12 Jan 2016 10:03:25
+1.44 V (using ferrocene/ferrocenium as an internal stan-
Copyright: American Scientific Publishers
dard at +0.7 V). The oxidation potential of compounds 3
and 4 (3; Eox = +1.32 V, 4; Eox = +1.33 V) is slightly
(a)
(b)
HOMO: -5.47 eV
HOMO: -5.35 eV
HOMO: -5.36 eV
LUMO: -0.74 eV
LUMO: -0.78 eV
LUMO: -1.58 eV
HOMO: -5.39 eV
HOMO: -5.31 eV
HOMO: -5.41 eV
LUMO: -1.22 eV
LUMO: -1.21 eV
LUMO: -1.55 eV
(c)
(d)
(e)
(f)
Figure 3. Molecular orbital surfaces of HOMO and LUMO by DFT calculation of compounds (a) 1, (b) 2, (c) 3, (d) 4, (e) 5, and (f) 6.
J. Nanosci. Nanotechnol. 16, 910–919, 2016
916

Lee et al.
Novel Organic Semiconductors Based on Phenyl and Phenylthienyl Derivatives for Organic Thin-Film Transistors
4
4
10
10
LUMO distribution; the HOMO and LUMO was localized
Compound 1
Compound 4
on the carbazole and ꢁ-carboline moiety, respectively.
3
3
10
10
3.5. Thin-Film Transistor Characterization
2
2
4
10
10
New phenyl and phenylthienyl derivatives were tested as
organic semiconductors for top-contact/bottom gate OTFT
devices. All of the compounds were vacuum-deposited
on bare, HMDS-treated, OTMS-treated, PS-coated, and
4
10
10
Compound 2
Compound 5
3
3
10
10
2
2
4
10
10
ꢀ
PMMA-coated SiO2/Si substrates at 20 and 60 C. The
4
10
10
representative device characteristics are shown in Figure 4.
Overall, devices were not active on hydrophilic bare
SiO2/Si substrates. Devices based on thin films of com-
pounds 1–6 (except compound 2) exhibited p-channel
activity with relatively low device performance (vide
infra). The OTFT devices exhibited carrier mobilities of
10−5–10−7 cm2/Vs and a current on/off ratio of ∼102–104.
Unfortunately, no clear correlation between device perfor-
mance, surface treatment, and deposition temperature was
found in this series of compounds. Of the compounds that
were employed in this study, compound 5 exhibited the
5
10
10
15
15
20
25
30
Compound 3
Compound 6
3
3
2
1
10
10
10
10
2
10
1
10
5
10
15
20
25
30
5
20
25
30
2 Theta (degrees)
2 Theta (degrees)
Figure 5. ꢈ–2ꢈ XRD scans of thin films of compounds 1–6.
CV measurement) and the bandgap (from UV-vis measure-
ment), as shown in Table I.
3.4. Theoretical Calculation
The molecular structure and HOMO/LUMO energy distri-
bution of phenyl and phenylthienyl derivatives were deter-
mined by DFT (B3LYP) calculation with 6-31G basis
sets (Fig. 3). Overall, strong electron-donating character of
Delivered by Publishing Technology to: McMaster University
nitrogen of the carbazole and electron-accepting charac-
IP: 179.106.152.75 On: Tue, 12 Jan 2016 10:03:25
Copyright: American Scientific Publishers
ter of the ꢁ-carboline are projected on the HOMO/LUMO
energy distribution. For compounds with only carbazole
moieties on both ends (compounds 1, 3, 5, and 6), the
HOMO was rather dispersed over the whole molecule
(except compound 6), while the LUMO was either dis-
persed (compounds 1 and 3) or localized on the phenylth-
iophene moieties (compounds 5 and 6). On the other hand,
compounds with both carbazole and ꢁ-carboline on both
ends (compounds 2 and 4) exhibited localized HOMO and
Table II. TFT device performance parameters based on thin films of
compounds 1–6 employed in this study (TD: deposition temperature, ꢃ:
carrier mobility, Ion/Ioff: current on/off ratio,VT ; threshold voltage).
Surface
Compound treatment TD (ꢀC) ꢃ (cm2/Vs)
Ion/Ioff
VT (V)
1
HMDS
PS
PMMA
60
20
60
2.2×10−6
1.7×10−7
3.5×10−7
Not active
5.4×10−6
3.2×10−6
1.4×10−6
1.3. ×10−6
1.7×10−5
1.5×10−5
7.4×10−6
2.1×10−6
2.1×10−7
1.8×102
2.7×101
3.1×101
−30
−26
−55
2
3
PS
60
60
20
20
60
60
60
60
60
1.1×102
4.2×102
1.2×102
1.0×102
8.2×103
2.6×104
4.5×103
4.3×101
4.0×101
−44
−49
−56
−55
−23
−26
−40
−65
−32
PMMA
OTMS
PMMA
PS
OTMS
HMDS
PS
4
5
Figure 6. AFM image (5×5 ꢃm2ꢅ of thin films (70 nm) of (a) com-
pound 1 (on PMMA at 60 ꢀC), (b) compound 2 (on Bare at 60 ꢀC),
(c) compound 3 (on PMMA at 20 ꢀC), (d) compound 4 (on PMMA at
20 ꢀC), (e) compound 5 (on HMDS at 60 ꢀC), and (f) compound 6 (on
PS at 60 ꢀC).
6
PMMA
J. Nanosci. Nanotechnol. 16, 910–919, 2016
917

Novel Organic Semiconductors Based on Phenyl and Phenylthienyl Derivatives for Organic Thin-Film Transistors
Lee et al.
highest device performance with carrier mobility as high
4. (a) I. Kang, S. M. Park, D. H. Lee, S. H. Han, D. S. Chung, Y. H.
Kim, and S. K. Kwon, Sci. Adv. Mater. 5, 199 (2013); (b) D. D.
Tullio, M. Magliulo, G. Colafemmina, K. Manoli, L. Torsi, and
G. Palazzo, Sci. Adv. Mater. 5, 1922 (2013).
as 1ꢂ7 ×10−5 cm2/Vs.
3.6. Thin-Film Microstructure and Morphology
Film microstructure and surface morphology of vacuum-
deposited films were characterized using wide-angle ꢈ–2ꢈ
XRD and AFM to evaluate device performance. Devices
with high electrical performance generally exhibit films
with high film crystallinity and large grain size. Figure 5
shows conventional ꢈ/2ꢈ XRD scans of thin films based
on compounds 1–6. As shown, all of films did not exhibit
any significant Bragg reflections, indicating poor film tex-
ture. Furthermore, surface morphologies of organic semi-
conductor thin films (70 nm) were characterized by AFM
(Fig. 6). As shown, thin films of phenyl and phenylthienyl
derivatives showed either ball-shaped grains with small
grain sizes (compounds 1, 3, and 4) or relatively smooth
surface (compounds 2, 5, and 6).
5. J. E. Anthony, J. S. Brooks, D. L. Eaton, and S. R. Parkin, J. Am.
Chem. Soc. 123, 9482 (2001).
6. T. Okamoto and Z. Bao, J. Am. Chem. Soc. 129, 10308 (2007).
7. K. Xiao, Y. Q. Liu, T. Qi, W. Zhang, F. Wang, J. H. Gao, W. F. Qiu,
Y. Q. Ma, G. L. Cui, S. Y. Chen, X. W. Zhan, G. Yu, J. G. Qin,
W. P. Hu, and D. Zhu, J. Am. Chem. Soc. 127, 13281 (2005).
8. I. McCulloch, M. Heeney, C. Bailey, K. Genevicius, I. Macdonald,
M. Shkunov, D. Sparrowe, S. Tierney, R. Wagner, W. Zhang, M. L.
Chabinyc, R. J. Kline, M. D. McGehee, and M. F. Toney, Nat. Mater.
5, 328 (2006).
9. Y. Wu, P. Liu, S. Gardner, and B. S. Ong, Chem. Mater. 17, 221
(2005).
10. M. C. Chen, C. Kim, S. Y. Chen, Y. J. Chiang, M. C. Chung,
A. Facchetti, and T. J. Marks, J. Mater. Chem. 18, 1029 (2008).
11. (a) H. Yan, Z. H. Chen, Y. Zheng, C. Newman, J. R. Quinn, F. Dotz,
M. Kastler, and A. Facchetti, Nature 457, 679 (2009); (b) B. Kang,
M. Jang, Y. Chung, H. Kim, S. K. Kim, J. H. Oh, and K. Cho, Nat.
Commun. 5, 4752 (2014).
12. (a) M. Alonzi, D. Lanari, A. Marrocchi, C. Petrucci, and L. Vaccaro,
RSC Advances 3, 23909 (2013); (b) C. Kim, A. Facchetti, and T. J.
Marks, Science 318, 76 (2007).
13. (a) T. K. An, S. M. Park, S. Nam, J. Hwang, S. J. Yoo, M. J. Lee,
W. M. Yun, J. Jang, H. Cha, J. Hwang, S. Park, J. Kim, D. S.
Chung, Y. H. Kim, S. K. Kwon, and C. E. Park, Sci. Adv. Mater.
5, 1323 (2013); (b) A. Chowdhury, B. Biswas, and B. Mallik, Sci.
Adv. Mater. 5, 1297 (2013); (c) O. T. Kwon, J. D. Seo, W. K. Han,
K. W. Jang, J. W. Hong, and T. W. Kim, Sci. Adv. Mater. 6, 2343
(2014).
4. CONCLUSIONS
A
family of new phenyl and phenylthienyl end-
functionalized with carbazole and/or ꢁ-carboline moiety
was synthesized and characterized. Thin-film transis-
tors fabricated from these molecules exhibited p-channel
device characteristics with relatively low electrical perfor-
mance, possibly due to poor film microstructure and grain
Delivered by Publishing Technol1o4g. y(at)oJ:. MJ.cPMarka,sWte. rJ.UHnyiuvne, rKs.itHy. Park, S. H. Im, and O. O. Park,
morphology. Further molecular engineering on phenyl and
IP: 179.106.152.75 On: Tue, 12 Jan 2016 10:03:25
Sci. Adv. Mater. 6, 2370 (2014); (b) J. K. Kim and S. K. Park, Sci.
Adv. Mater. 6, 2400 (2014); (c) H. Kim, D. S. Song, S. M. Kim,
phenylthienyl derivatives are in progreCsos.pyright: American Scientific Publishers
J. H. Jung, J. H. Kwon, D. K. Kim, G. Horowitz, M. Choi, I. M.
Kang, and J. H. Bae, Sci. Adv. Mater. 6, 2483 (2014); (c) W. M.
Yun, J. Jang, S. Nam, C. E. Park, S. H. Kim, and D. S. Chung, Sci.
Adv. Mater. 6, 1676 (2014).
Acknowledgments: This research was supported by
Basic Science Research Program through the National
Research Foundation of Korea (NRF) funded by the
Ministry of Science, ICT and Future Planning (NRF-
2012R1A1A1007364), and was supported by the Human
Resources Development program (No. 20114010203090)
of the Korea Institute of Energy Technology Evaluation
and Planning (KETEP) grant funded by the Korea govern-
ment Ministry of Trade, Industry and Energy.
15. (a) M. A. Mohd Sarjidan, N. Jubri, S. H. Basri, N. K. Za’aba, M. S.
Zaini, S. N. Zaini, and W. H. Abd Majid, Nanosci. Nanotechnol. Lett.
6, 1035 (2014); (b) C.-W. Li, S.-P. Chang, and S.-J. Chang, Nanosci.
Nanotechnol. Lett. 6, 273 (2014); (c) H. Cui, T. D. Zeng, L. Shi,
S. Fang, G. Chen, X. Xu, and C. Xu, Nanosci. Nanotechnol. Lett.
5, 209 (2013); (d) Y. He, X. Li, and L. Que, J. Biomed. Nanotechnol.
10, 767 (2014).
16. (a) C. R. Newman, C. D. Frisbie, D. A. da Silva Filho, J. L. Breìdas,
P. C. Ewbank, and K. R. Mann, Chem. Mater. 16, 4436 (2004);
(b) A. Facchetti, L. Vaccaro, and A. Marrocchi, Angew. Chem. Int.
Ed. 51, 3520 (2012).
17. P. Strohriegl, D. Wagner, P. Schrögel, S. T. Hoffmann, A. Köhler,
U. Heinemeyer, and I. Munster, Proc. SPIE 8829, 882906 (2013).
18. K. Brunner, A. V. Dijken, H. Borrner, J. J. A. M. Bastiaansen, N. M.
M. Kiggen, and B. M. W. Langeveld, J. Am. Chem. Soc. 126, 6035
(2004).
19. Y. Im and J. Y. Lee, Chem. Commun. 49, 5948 (2013).
20. B. S. Kim and J. Y. Lee, Org. Eeletron. 14, 3024 (2013).
21. (a) Y. Wu, Y. Li, S. Gardner, and B. S. Ong, J. Am. Chem. Soc. 127,
614 (2005); (b) J. Han, B. Thirupathaiah, G. Kwon, C. Kim, and
S. Seo, Dyes Pigments 114, 78 (2015).
References and Notes
1. (a) M. Berggren, D. Nilsson, and N. D. Robinson, Nat. Mater. 6, 3
(2007); (b) T. Sekitani and T. Someya, Adv. Mater. 22, 2228 (2010).
2. (a) J. Baek, N. S. Kang, Y. D. Lee, B. H. Kang, K. Y. Dong, J. A.
Lim, Y. W. Song, J. M. Hong, and B. K. Ju, Sci. Adv. Mater. 5, 1775
(2013); (b) K. Fan, R. Li, J. Chen, W. Shi, and T. Peng, Sci. Adv.
Mater. 5, 1596 (2013); (c) R. Deng, L. Zhou, M. Song, Z. Hao,
and H. Zhang, Sci. Adv. Mater. 5, 1556 (2013); (d) V. Palanianthan,
N. Chauhan, A. C. Poulose, S. Raveendran, T. Mizuki, T. Hasumura,
T. Fukuda, H. Morimoto, Y. Yoshida, T. Maekawa, and D. S. Kumar,
Mater. Express 4, 415 (2014); (e) Y. A. K. Reddy, B. Ajitha, and
P. S. Reddy, Mater. Express 4, 32 (2014); (f) S. B. Choi, H. Zhao,
L. S. Pu, J. H. Cho, and J. Y. Lee, Sci. Adv. Mater. 6, 2338 (2014).
3. (a) H. Usta, C. Kim, Z. Wang, S. Lu, H. Huang, A. Facchetti, and
T. J. Marks, J. Mater. Chem. C 22, 4459 (2012); (b) A. C. Arias,
J. D. Mackenzi, I. McCulloch, J. Rivnay, and A. Salleo, Chem. Rev.
110, 3 (2010).
22. (a) W. Y. Hung, G. M. Tu, S. W. Chen, and Y. Chi, J. Mater. Chem.
22, 5410 (2012); (b) C. H. Chen, F. L. Wu, Y. Y. Tsai, and C. H.
Cheng, Adv. Funct. Mater. 21, 3150 (2011).
23. T. Thoms, S. Okada, J. P. Chen, and M. Furugori, Thin Solid Films
436, 264 (2003).
24. (a) H. Shimizu, A. Kobayashi, S. Itoi, T. Yoshihara, S. Tobita,
Y. Nakamura, and J. Nishimura, Heterocycles 78, 1265 (2009);
918
J. Nanosci. Nanotechnol. 16, 910–919, 2016

Lee et al.
Novel Organic Semiconductors Based on Phenyl and Phenylthienyl Derivatives for Organic Thin-Film Transistors
(b) Y. H. Chen, Y. Y. Lin, Y. C. Chen, J. T. Lin, R. H. Lee, W. J. Kuo,
and R. J. Jeng, Polymer 52, 976 (2011); (c) J. K. Kwon, J. H. Cho,
(b) T. Ishiyama, J. Takagi, Y. Yonekawa, J. F. Hartwig, and N.
Miyaura, Adv. Synth. Catal. 345, 1103 (2003).
Y. S. Ryu, S. H. Oh, and E. K. Yum, Tetrahedron 67, 4820 (2011);
(d) J. You, G. Li, and Z. Wang, Org. Biomol. Chem. 10, 9481 (2012);
(e) P. Rajakumar, K. Sekar, and N. Venkatesan, Synlett 23, 2504
(2012); (f) J. Y. Hu, Y. J. Pu, Y. Yamashita, F. Satoh, S. Kawata,
H. Katagiri, H. Sasabe, and J. Kido, J. Mater. Chem. C 1, 3871
(2013); (g) W. Lee, J. Y. Seng, and J. I. Hong, Tetrahedron 69, 9175
(2013).
27. (a) A. S. Demir, Ö. Reis, and M. Emrullahog˘lu, Tetrahedron 58, 8055
(2002); (b) H. Jullien, B. Quiclet-Sire, T. Teìtart, and S. Z. Zard,
Org. Lett. 16, 302 (2014); (c) A. A. Kiryanov, P. Sampson, and A. J.
Seed, J. Org. Chem. 66, 7925 (2001); (d) S. Hotta, H. Kimura, S. A.
Lee, and T. Tamaki, J. Heterocyclic Chem. 37, 281 (2000); (e) N.
Uchiyama, E. Shirakawa, R. Nishikawa, and T. Hayashi, Chem. Com-
mun. 47, 11671 (2011); (f) R. Hirase, M. Ishihara, T. Katagiri, Y.
Tanaka, H. Yanagi, and S. Hotta, Org. Electron. 15, 1481 (2014).
28. (a) L. Torun, B. K. Madras, and P. C. Meltzer, Bioorg. Med. Chem.
20, 2762 (2012); (b) A. S. Demir, Ö. Reis, and M. Emrullahoglu,
J. Org. Chem. 68, 578 (2003).
25. (a) B. R. Kaafarani, A. O. El-Ballouli, R. Trattnig, A. Fonari, S. Sax,
B. Wex, C. Risko, R. S. Khnayzer, S. Barlow, D. Patra, T. V.
Timofeeva, E. J. W. List, J. L. Brédas, and S. R. Marder, J. Mater.
Chem. C 1, 1638 (2013); (b) Y. Chen, D. Han, T. Wang, and X. Li,
Ind. Eng. Chem. Res. 52, 3646 (2013); (c) Q. Zhang, J. Chen,
Y. Cheng, L. Wang, D. Ma, X. Jinga, and F. Wanga, J. Mater. Chem.
14, 895 (2004).
29. (a) H. S. Jung, H. H. Cho, and S. H. Kim, Tetrahedron Lett. 54, 960
(2013); (b) L. T. Ball, G. C. Lloyd-Jones, and C. A. Russell, J. Am.
Chem. Soc. 136, 254 (2014).
26. (a) Y. Dienes, S. Durben, T. Kárpáti, T. Neumann, U. Englert,
L. Nyulaszi, and T. Baumgartner, Chem. Eur. J. 13, 7487 (2007);
30. S. M. Sze, Semiconductor Devices: Physics and Technology, Wiley,
New York (1981).
Received: 27 November 2014. Accepted: 21 December 2014.
Delivered by Publishing Technology to: McMaster University
IP: 179.106.152.75 On: Tue, 12 Jan 2016 10:03:25
Copyright: American Scientific Publishers
J. Nanosci. Nanotechnol. 16, 910–919, 2016
919