Arylamino-9,10-diphenylanthracenes for organic light emitting devices

Article abstract of DOI:10.1016/j.orgel.2009.12.001

Hole-transporting arylamino-9,10-diphenylanthracene derivatives were synthesized by C-N cross coupling with palladium catalyst. The materials showed higher glass transition temperatures (135-177 °C) than that of a conventional hole-transporting material, N,N'-bis(naphthalen-1-yl)-N,N'-bis(phenyl)benzidine (NPD). The compounds all showed higher hole mobilities than that of NPD, with one of the compounds showing a much higher hole mobility of ～1.0 × 10^-2 cm² V^-1s^-1. Tris-(8-quinolinolato) aluminum (Alq₃)-based green light emitting devices containing the arylamino-9,10-diphenylanthracene derivatives as hole transport layers were fabricated. The devices containing the anthracene derivatives showed lower driving voltages and higher efficiencies compared with those of the equivalent device containing NPD. The anthracene derivative with a dibenzofuran substituent was also used as the emitting material in a device. This device emitted blue light with high efficiencies of 5.0 lm/W and 6.3 cd/A at 4.0 V and 1000 cd/m², respectively.

Full text of DOI:10.1016/j.orgel.2009.12.001

Organic Electronics 11 (2010) 479–485
Contents lists available at ScienceDirect
Organic Electronics
journal homepage: www.elsevier.com/locate/orgel
Arylamino-9,10-diphenylanthracenes for organic light emitting devices
*
*
Yong-Jin Pu , Akinori Kamiya, Ken-ichi Nakayama, Junji Kido
Department of Organic Device Engineering, Yamagata University, Yonezawa, Yamagata 992-8510, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 26 October 2009
Received in revised form 20 November 2009
Accepted 1 December 2009
Available online 16 December 2009
Hole-transporting arylamino-9,10-diphenylanthracene derivatives were synthesized by C–
N cross coupling with palladium catalyst. The materials showed higher glass transition
temperatures (135–177 °C) than that of a conventional hole-transporting material, N,N’-
bis(naphthalen-1-yl)-N,N’-bis(phenyl)benzidine (NPD). The compounds all showed higher
hole mobilities than that of NPD, with one of the compounds showing a much higher hole
mobility of ꢀ1.0 Â 10À2 cm2 VÀ1sÀ1. Tris-(8-quinolinolato) aluminum (Alq3)-based green
light emitting devices containing the arylamino-9,10-diphenylanthracene derivatives as
hole transport layers were fabricated. The devices containing the anthracene derivatives
showed lower driving voltages and higher efficiencies compared with those of the equiv-
alent device containing NPD. The anthracene derivative with a dibenzofuran substituent
was also used as the emitting material in a device. This device emitted blue light with high
efficiencies of 5.0 lm/W and 6.3 cd/A at 4.0 V and 1000 cd/m2, respectively.
Keywords:
Organic light emitting diode
Hole transporting
Anthracene
Blue emitting
Arylamine
Ó 2009 Elsevier B.V. All rights reserved.
1. Introduction
compounds [13], so arylamino-9,10-diphenylanthracene
derivatives are expected to exhibit good hole transport
Organic light emitting devices (OLEDs) have attracted a
great deal of attention because of their application in flat
panel displays [1] and general lighting [2,3]. Since organic
electroluminescence was first reported by Pope et al. from
properties. High hole mobility, in addition to a small hole
injection barrier, is an important parameter in reducing
the energy consumption of OLEDs because it reduces the
required driving voltage. 9,10-Diphenylanthracene deriva-
a single crystal of anthracene [4], thousands of
p-conju-
tives 1–6 containing bulky p-conjugated arylamino groups
gated molecules have been developed as charge transport
and/or light emitting materials for OLEDs. Among these
numerous compounds, 9,10-diphenylanthracene deriva-
tives have played a leading role as host or emitting mate-
rials in highly efficient and long-lived state-of-the-art
OLEDs [5–10]. 9,10-Diphenylanthracene itself shows
strong blue emission but it has high crystallinity, which
is a severe drawback for device stability in OLED applica-
tions. To make 9,10-diphenylanthracene amorphous,
arylamino substituents were introduced and blue emission
from OLEDs containing these arylamino-9,10-diphenylan-
thracene derivatives was reported [11,12]. Generally, aryl-
amine groups increase the hole-transporting ability of the
were synthesized. Their glass transition temperature, hole
mobilities and performance as a hole-transporting mate-
rial in OLEDs were investigated. The compound with a
dibenzofuran substituent 5 exhibited high efficiency as a
blue emitting material in OLEDs.
2. Results and discussion
2.1. Synthesis and thermal properties
Arylaminoanthracene derivatives 1–6 were synthesized
by the Pd(0)-catalyzed C–N cross-coupling reaction of
9,10-bis(4-(phenylamino)phenyl)anthracene and an aryl-
halide (Scheme 1). Purification of the compounds was
made difficult by their poor solubility in common organic
solvents. Diethylfluorene-substituted compound 4 showed
* Corresponding authors.
E-mail addresses: pu@yz.yamagata-u.ac.jp (Y.-J. Pu), kid@yz.yamagata-
u.ac.jp (J. Kido).
1566-1199/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.orgel.2009.12.001

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Y.-J. Pu et al. / Organic Electronics 11 (2010) 479–485
Pd2(dba)3, P(t-Bu)3
1 –6
NaO-t-Bu, xylene
H
N
N
H
Ar-Br or Ar-I
N
N
N
N
N
N
1
2
3
O
S
N
N
N
N
N
N
O
S
4
5
6
Scheme 1. Synthetic route and chemical structure of compounds 1–6.
the best solubility in chloroform, and 1 and 2 were also sol-
uble in chloroform. The compounds with bulky aryl groups
(3, 5 and 6) showed poor solubility, especially 3 which con-
tained a bulky phenanthrene substituent. Only 3 was not
able to be purified by column chromatography with chlo-
roform; a solution of 3 in hot dichlorobenzene was passed
through a short silica column to remove highly polar impu-
rities. After column chromatography, all of the compounds
were further purified by train sublimation with two heat-
ing zones at pressures under 5.0 Â 10À2 Pa for 1 and 2,
and under 5.0 Â 10À4 Pa for 3–6. Thermogravimetric anal-
ysis (TGA) showed that the decomposition temperatures
(Td) with loss of 5 wt% of the compounds were over
400 °C. Differential scanning calorimetry thermograms of
the compounds are shown in Fig. 1. The glass transition
temperatures (Tg) of 2–6 (Table 1) were higher than the
Tg
of
100 °C
of
N,N’-bis(naphthalen-1-yl)-N,N’-
bis(phenyl)benzidine (NPD). Compound 3 showed the
highest Tg of 177 °C because of the bulky phenanthrene
substituent. On the other hand, a Tg for 1, which has a sym-
metrical structure and simple phenyl substituent, was not
observed in our experiment, probably because of its high
crystallinity.
Fig. 1. DSC thermograms of the compounds.
length maxima located around 480–490 nm. The PL quan-
tum efficiency (PLQE) of wt% doped poly-
1
methylmethacrylate (PMMA) films and neat films of the
anthracenes were determined using an integrating sphere.
All the compounds showed a high PLQE of around 80% in a
diluted film, which suggests that these anthracene com-
pounds should be useful as emitting dopants in OLEDs.
The ionization potential (Ip) of each compound, which gen-
erally corresponds to the energy level of the highest occu-
pied molecular orbital (HOMO), was measured by
2.2. Photophysical and electrochemical properties
UV absorption and PL spectra of solutions and films on a
quartz substrate of 1–6 were measured (Fig. 2). All of the
compounds except 4 showed three absorption peaks be-
tween 360 and 400 nm which were ascribed to the vibra-
tional structure of the central anthracene moiety. All of
the compounds 1–6 exhibited blue emission with wave-

Y.-J. Pu et al. / Organic Electronics 11 (2010) 479–485
481
Table 1
Thermal and optoelectrochemical properties of compounds 1–6.
Tg
(°C)
Td
(°C)
UV/nm (log
Chloroform
e
)
PL
U
Eg
Ip
(eV)
Ea
(nm)a
(%)b
(eV)c
(eV)d
2.98
2.99
3.00
2.94
2.98
Film
e
1
2
3
4
5
–
479
474
494
438
511
258 (4.91), 306 (4.70),360 (4.00),
380 (4.22),398 (4.28)
258 (5.03), 305 (4.67),360 (4.35),
379 (4.40),398 (4.39)
257 (5.30), 297 (4.70),361 (4.35),
378 (4.37),398 (4.33)
259 (5.03),339 (4.76),
263, 306, 363, 384, 402
475 (468)
494 (482)
471 (470)
489 (474)
490 (483)
85 (30)
81 (26)
83 (41)
70 (28)
87 (34)
2.82
2.77
2.74
2.73
2.72
5.80
5.76
5.74
5.67
5.70
146
177
135
147
262, 305, 364, 383, 403
259, 299, 367, 383, 404
262, 337, 404
398 (4.37)
253 (4.01), 260 (3.97),293 (3.80),
301 (3.86),315 (3.64),361 (3.18),
379 (3.28),398 (3.27)
254, 265, 293, 318, 301, 364,
384, 405
6
162
517
259 (5.14),311 (4.84),360 (4.21),
379 (4.34),398 (4.34)
261, 312, 364, 384, 404
488 (484)
84 (6)
2.75
5.68
2.93
a
b
c
Chloroform solution (neat film).
1 wt% Doped PMMA film (neat film).
Estimated from the onset of UV absorption of the film.
Eg–Ip.
d
e
Not detected between À30 and 400 °C.
1.2
1
1.2
1
1.2
1.2
1
2
2
1
2
3
1
1.5
1
1.5
1
0.8
0.6
0.4
0.2
0
0.8
0.6
0.4
0.2
0
0.8
0.6
0.4
0.2
0
0.8
0.6
0.4
0.2
0
0.5
0
0.5
0
300
400
500
600
300
400
500
600
300
400
500
600
Wavelength (nm)
Wavelength (nm)
Wavelength (nm)
1.2
1
1.2
1
1.5
1
1.5
1
1.2
1
1.2
1
4
5
6
0.8
0.6
0.4
0.2
0
0.8
0.6
0.4
0.8
0.6
0.4
0.2
0
0.8
0.6
0.4
0.2
0
0.5
0
0.5
0
0.2
0
300
400
500
600
300
400
500
600
300
400
500
600
Wavelength (nm)
Wavelength (nm)
Wavelength (nm)
Fig. 2. UV–vis and PL spectra of chloroform solutions (dashed line) and films (solid line) of 1–6.
photoelectron yield spectroscopy. The electron affinity (Ea),
which generally corresponds to the energy level of the
lowest unoccupied molecular orbital (LUMO), was tenta-
tively estimated from the difference between Ip and the
optical energy gap (Eg). All of the compounds showed sim-
ilar Ip and Ea, meaning the HOMO and LUMO energy levels
were almost independent of the attached substituents. The
Ip of 1 was a little higher than the other compounds be-
cause its phenyl substituent is less electron-donating than
the other aryl substituents.
2.3. Hole mobilities and OLED characteristics
The hole mobilities of the compounds were estimated
by time-of-flight (TOF) measurements (Fig. 3). Com-
pounds 1, 3, and 6 exhibited slightly higher mobilities
of around 10À3 cm2 VÀ1sÀ1 than that of NPD, and diethyl-
fluorene-substituted 4 exhibited much a higher mobility
of close to 10À2 cm2 VÀ1sÀ1 (Fig. 4). The detailed condi-
tion and nondispersive photocurrents of 4 at 10 different
electric fields are shown in Supporting information.

482
Y.-J. Pu et al. / Organic Electronics 11 (2010) 479–485
4
3
2
20
15
10
2
10-3
10-4
10-5
10-2
10-2
1
2
3
10-3
10-4
10-5
10-3
10-4
10-5
1.5
1
10-1
101
10-1
100
101
10-1
100
101
1
0
Time (µsec)
5
0
Time (µsec)
0.5
0
Time (µsec)
0
1
2
3
4
0
1
2
3
4
0
0.5
1
1.5
2
Time (µsec)
Time (µsec)
Time (µsec)
20
15
10
20
15
10
10
8
10-2
10-2
10-1
4
5
6
10-3
10-4
10-5
10-2
10-3
10-4
10-3
6
4
10-4
10-2
10-1
100
101
10-1
100
Time (µsec)
101
10-1
Time (µsec)
100
Time (µsec)
5
0
5
0
2
0
0
0.5
1
1.5
0
1
2
3
4
0
0.5
1
1.5
Time (µsec)
Time (µsec)
Time (µsec)
Fig. 3. Transient photocurrents obtained from TOF measurements. (Inset) Double logarithmic plot of the TOF data.
1 x 10-1
pounds was observed for these devices. The hole injec-
tions from ITO to the compounds should be poor
because of their large Ips, and those hole injection abili-
ties mainly determined the device performance rather
than the hole mobilities. To explain the device perfor-
mance from the perspective of the materials in the
HTL, the hole injection ability from ITO in a hole-only
device has to be taken into account. Dibenzofuran-substi-
tuted 5 was used as a blue emitter in a device with the
1
2
3
4
5
6
1 x 10-2
NPD
1 x 10-3
1 x 10-4
configuration
bis(naphthalen-2-yl)anthracene (MADN):
(30 nm)/1,4-di(1,10-phenanthrolin-3-yl)benzene
of
ITO/NPD
(50 nm)/2-methyl-9,10-
5
(10 wt%)
(DPB)
(20 nm)/LiF (0.5 nm)/Al (100 nm). The device exhibited
blue emission from 5, with a maximum wavelength of
468 nm and Commission Internationale de L’Éclairage
(CIE) chromaticity coordinates of (0.14, 0.21). The device
efficiencies were as high as 5.0 lm/W and 6.3 cd/A at
1000 cd/m2, meaning that these arylaminoanthracene
derivatives could be useful as not only hole-transporting
materials but also as blue emitting dopants in OLEDs.
(Fig. 6).
300
400
500
600
700
800
E1/2 (Vcm-1)1/2
Fig. 4. Hole mobilities of compounds 1–6.
OLEDs with the configuration of ITO/HTL: 1–6 or NPD
(40 nm)/Alq3 (60 nm)/LIF (0.5 nm)/Al (100 nm) were fab-
ricated. The luminance–voltage and current density–volt-
age plots are shown in Fig. 5, and the device efficiencies
are summarized in Table 2. OLEDs containing 1–6
showed comparable driving voltages and efficiencies to
those of NPD. The OLED containing naphthalene-substi-
tuted 2 exhibited a lower driving voltage by 0.6 V and
1.4 times higher efficiency at 1000 cd/m2 than those of
the device containing NPD. No correlation between the
device efficiency and the high hole mobility of the com-
3. Conclusion
Arylamino-9,10-diphenylanthracene derivatives were
synthesized and purified by train sublimation. Their Tg
ranged from 135 to 177 °C because of their bulky aryl sub-
stituents. The compounds all showed higher hole mobili-
ties than that of NPD, and diethylfluorene-substituted
4
showed
a
much higher hole mobility of

Y.-J. Pu et al. / Organic Electronics 11 (2010) 479–485
483
7000
6000
5000
4000
160
140
120
100
80
1
1
2
3
4
5
6
2
3
4
5
6
NPD
NPD
3000
2000
1000
0
60
40
20
0
0
1
2
3
4
5
6
7
8
0
1
2
3
4
5
6
7
8
Voltage (V)
Voltage (V)
Fig. 5. Current density–voltage and luminance–voltage plots of the OLEDs containing 1–6 as the HTL.
Table 2
Device efficiencies at 100 cd mÀ2 and 1000 cd mÀ2
.
HTL
100 (cd mÀ2
Voltage (V)
)
1000 (cd/m2)
Voltage (V)
gP (lm WÀ1
)
gC (cd AÀ1
)
gEXT (%)
gP (lm WÀ1
)
gC (cd AÀ1
)
gEXT (%)
1
2
3
4
5
6
4.3
4.0
4.2
4.4
4.1
3.9
4.3
3.3
3.2
3.6
3.0
2.6
3.1
2.1
2.3
4.9
4.3
4.6
3.9
3.6
4.0
2.5
3.3
5.1
1.4
1.5
1.3
1.2
1.3
0.8
1.0
3.3
6.1
5.7
6.1
6.3
5.9
5.5
6.3
4.0
2.3
2.7
2.1
1.9
1.8
2.1
1.7
5.0
4.4
4.9
4.1
3.9
3.4
3.8
3.4
6.3
1.5
1.6
1.3
1.3
1.1
1.2
1.1
4.0
NPD
5 (EML)
800
600
400
200
0
25000
1
0.8
0.6
0.4
0.2
20000
15000
10000
5000
0
0
400
500
600
700
Wavelength (nm)
0
2
4
6
8
10
Volltage (V)
Fig. 6. Current density–voltage and luminance–voltage plots of the blue-emitting OLED containing 5 as the emitting dopant. (Inset) EL spectrum of the
OLED.
ꢀ1.0 Â 10À2 cm2 VÀ1sÀ1. Lower driving voltages and higher
4. Experimental
efficiencies compared with those of NPD were achieved in
devices containing the anthracene derivatives as the HTL.
Dibenzofuran-substituted 5 was also used as a blue emit-
ting dopant, and a high device efficiency of 5.0 lm/W and
blue emission of CIE (0.14, 0.21) was achieved.
4.1. Characterization and OLED Fabrication
1H NMR spectra were measured in deuterated solvents
on a JEOL ECX 400 MHz spectrometer. Elemental analyses

484
Y.-J. Pu et al. / Organic Electronics 11 (2010) 479–485
were carried out by the Elemental Analysis Service, Yamag-
ata University, Japan. Mass spectra were obtained on a
JEOL JMS-K9 mass spectrometer. TGA was performed on
a Seiko SII EXSTAR 6000 and TGA/DTA 62000 analyzers.
DSC was performed on a Perkin–Elmer Diamond DSC7 cal-
orimeter. Ionization potentials were measured on a photo-
electron yield spectrometer (RIKEN KEIKI AC-3). UV–
visible absorption spectra were recorded of solutions in
chloroform or of film on quartz with a Shimadzu UV-
3150 spectrometer. PL spectra were recorded using a Jobin
Yvon Fluoromax-4 fluorometer. PL quantum efficiencies
were measured on a Hamamatsu C9920–01 integral sphere
system under nitrogen. TOF measurement was performed
on OPTEL TOF-401 system with N2 laser. OLEDs were fab-
ricated on ITO-coated glass substrates, which were pro-
vided by AGC Display Glass Yonezawa Co., Ltd. and
cleaned by ultrasonication sequentially in detergent, meth-
anol, 2-propanol and acetone, then exposure to UV-ozone
under ambient conditions for 20 min. Organic materials
were deposited by thermal evaporation at pressures less
than 2 Â 10À4 Pa. Lithium fluoride and aluminum were
deposited at a pressure less than 1 Â 10À3 Pa through a
shadow mask to form a cathode. The active area of each de-
vice is 2 Â 2 mm2. Layer thickness calibration was per-
formed using a Dektak 3 surface profilometer. EL spectra
were measured on a Hamamatsu PMA-11 photonic multi-
channel analyzer. The current–voltage characteristics and
luminance of the OLEDs were measured using a Keithley
2400 Source Meter and Konica Minolta CS-200 chromame-
ter, respectively. External quantum efficiencies were calcu-
sublimation at 5.0 Â 10À2 Pa with the zone temperatures
set at 330 °C and 310 °C . Yield: 0.63 g, 21%. 1H NMR
(400 MHz, CD2Cl2, ppm) d 6.99 (2H, td, J = 1.4, 7.25 Hz),
7.20–7.61 (28H, m), 7.80 (4H, dd, J = 3.2, 6.8 Hz), 7.86
(2H, d, J = 8.2 Hz), 7.96 (2H, d, J = 8.6 Hz), 8.12 (2H, d,
J = 8.2 Hz). EI-MS m/z Calcd: 765.0. Found: 765. Anal. Calcd
for C50H40N2: C, 91.07; H, 5.27; N, 3.66. Found: C, 91.05; H,
5.35; N, 3.62.
Compound 3: A mixture of 9,10-bis(4-(N-phenylami-
no)phenyl)anthracene (2.00 g, 3.90 mmol), 9-bromophe-
nanthrene (3.01 g, 11.7 mmol), sodium t-butoxide (1.12 g,
11.7 mmol),
(28 mg, 0.031 mmol),
tris(dibenzylideneacetone)dipalladium
tri-t-butylphosphine (8 mg,
0.04 mmol), and xylene (100 cm3) was heated at 100 °C
under nitrogen for 15 h. The mixture was allowed to cool
to room temperature, and the organic layer was washed
with water, dried over magnesium sulfate, and filtered.
The solvent was removed and the residue was dissolved
in hot dichlorobenzene. This solution was passed through
a short silica column and then the solvent was removed. Fi-
nally, the product was purified by train sublimation at
5.0 Â 10À4 Pa with the zone temperatures set at 327 °C
and 317 °C. Yield: 0.57 g, 17%. 1H NMR (400 MHz, CD2Cl2,
ppm) d 6.99–7.03 (2H, m), 7.24–7.39 (20H, m), 7.59–7.89
(16H, m), 8.23 (2H, d, J = 8.6 Hz), 8.75 (2H, d, J = 8.2 Hz),
8.81 (2H, d, J = 8.2 Hz). EI-MS m/z Calcd: 865.1. Found:
865. Anal. Calcd for C66H44N2: C, 91.64; H, 5.13; N, 3.24.
Found: C, 91.48; H, 4.83; N, 3.19.
Compound 4: 4 was prepared in the same manner as 1,
using 2-bromo-9,9-diethylfluorene instead of bromoben-
zene. The residue was purified by column chromatography
on silica gel using n-hexane/chloroform (2:1), followed by
train sublimation at 5.0 Â 10À4 Pa with the zone tempera-
tures set at 316 °C and 296 °C. Yield: 0.41 g, 11%. 1H NMR
(400 MHz, CD2Cl2, ppm) d 0.39 (12H, t, J = 7.3 Hz), 1.99
(8H, q, J = 7.3 Hz), 7.08 (2H, td, J = 1.4, 6.9 Hz), 7.23–7.43
(30H, d, J = 8.2 Hz), 7.67–7.71 (4H, m), 7.88 (4H, dd,
J = 3.2, 6.4 Hz). EI-MS m/z Calcd: 953.3. Found: 953. Anal.
Calcd for C72H60N2: C, 90.72; H, 6.34; N, 2.94. Found: C,
90.94; H, 6.34; N, 2.99.
Compound 5: 5 was prepared in the same manner as 1,
using 3-iododibenzofuran instead of bromobenzene. The
residue was purified by column chromatography on silica
gel using n-hexane/chloroform (3:2), followed by train
sublimation at 5.0 Â 10À4 Pa with the zone temperatures
set at 320 °C and 290 °C. Yield: 0.63 g, 19%. 1H NMR
(400 MHz, CD2Cl2, ppm) d 7.07 (2H, t, J = 7.02 Hz), 7.28–
7.52 (26H, m), 7.58–7.61 (4H, m), 7.86–7.95 (8H, m). EI-
MS m/z Calcd: 845.0. Found: 845. Anal. Calcd for
C62H40N2O2: C, 88.13; H, 4.77; N, 3.32. Found: C, 88.05;
H, 4.76; N, 3.29.
Compound 6: 6 was prepared in the same manner as 1,
using 3-iododibenzothiophene instead of bromobenzene.
The residue was purified by column chromatography on sil-
ica gel using n-hexane/chloroform (3:2), followed by train
sublimation at 5.0 Â 10À4 Pa with the zone temperatures
set at 340 °C and 324 °C. Yield: 0.38 g, 11%. 1H NMR
(400 MHz, CD2Cl2, ppm) d 7.10 (2H, t, J = 7.02 Hz), 7.31–
7.50 (26H, m), 7.84–7.90 (8H, m), 8.07–8.10 (4H, m). EI-MS
m/z Calcd: 877.1. Found: 877. Anal. Calcd for C62H40N2S2:
C, 84.90; H, 4.60; N, 3.19. Found: C, 84.85; H, 4.66; N, 3.19.
lated assuming
a Lambertian emission pattern and
considering all spectral features in the visible region.
4.2. Synthesis
9,10-bis-(4-(Phenylamino)phenyl)anthracene was pur-
chased from Wakayama Seika Kogyo Co., Ltd. All other
compounds were purchased from a general chemical com-
pany or synthesized.
Compound 1: A mixture of 9,10-bis(4-(N-phenylami-
no)phenyl)anthracene (2.00 g, 3.90 mmol), bromobenzene
(1.84 g, 11.7 mmol), sodium t-butoxide (1.12 g, 11.7 mmol),
tris(dibenzylideneacetone)dipalladium
(28 mg,
0.031 mmol), tri-t-butylphosphine (8 mg, 0.04 mmol) and
xylene (200 cm3) was heated at 100 °C under nitrogen for
15 h. The mixture was allowed to cool to room temperature,
then the organic layer was washed with water, dried over
magnesium sulfate and filtered. The solvent was removed
and then the residue was purified by column chromatogra-
phy on silica gel using n-hexane/chloroform (2:1), followed
by train sublimation at 5.0 Â 10À2 Pa with the zone temper-
atures set at 300 °C and 250 °C . Yield: 1.3 g, 51%. 1H NMR
(400 MHz, CD2Cl2, ppm) d 7.08 (4H, td, J = 0.9, 7.25 Hz),
7.25–7.36 (24H, m), 7.40 (4H, dd, J = 3.2, 6.8 Hz), 7.84 (4H,
dd, J = 3.2, 6.8 Hz). EI-MS m/z Calcd: 664.8. Found: 665. Anal.
Calcd for C50H36N2: C, 90.33; H, 5.46; N, 4.21. Found: C,
90.43; H, 5.54; N, 4.23.
Compound 2: 2 was prepared in the same manner as 1,
using 1-iodonaphthalene instead of bromobenzene. The
residue was purified by column chromatography on silica
gel using n-hexane/chloroform (3:2), followed by train

Y.-J. Pu et al. / Organic Electronics 11 (2010) 479–485
[2] F. So, J. Kido, P. Burrows, MRS Bull. 33 (2008) 663.
485
Acknowledgements
[3] S. Reineke, F. Lindner, G. Schwartz, N. Seidler, K. Walzer, B. Lüssem, K.
Leo, Nature 459 (2009) 234.
The authors thank AGC Display Glass Yonezawa Co., Ltd.
for providing ITO substrates, and Wakayama Seika Kogyo
Co., Ltd. for providing 9,10-bis-(4-(phenylamino)phenyl)
anthracene.
[4] M. Pope, H.P. Kallmann, P. Magnante, J. Chem. Phys. 38 (1963)
2042.
[5] C. Adachi, T. Tsutsui, S. Saito, Appl. Phys. Lett. 56 (1990) 799.
[6] T.J. Boyd, Y. Geerts, J.K. Lee, D.E. Fogg, G.G. Lavoie, R.R. Schrock, M.F.
Rubner, Macromolecules 30 (1997) 3553.
[7] T.J. Boyd, R.R. Schrock, Macromolecules 32 (1999) 6608.
[8] L. Wang, W.Y. Wong, M.F. Lin, W.K. Wong, K.W. Cheah, H.L. Tam, C.H.
Chen, J. Mater. Chem. 18 (2008) 4529.
Appendix A. Supplementary data
[9] V.V. Jarikov, D.Y. Kondakov, C.T. Brown, J. Appl. Phys. 102 (2007)
104908.
[10] Y.Y. Lyu, J. Kwak, O. Kwon, S.H. Lee, D. Kim, C. Lee, K. Char, Adv.
Mater. 20 (2008) 2720.
[11] M. Tamano, T. Enokida, US Patent 5811834, 1997.
[12] K. Danel, T.H. Huang, J.T. Lin, Y.T. Tao, C.H. Chuen, Chem. Mater. 14
(2002) 3860.
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.orgel.2009.
12.001.
References
[13] Y. Shirota, H. Kageyama, Chem. Rev. 107 (2007) 953.
[1] T. Urabe, T. Sasaoka, K. Tatsuki, J. Takaki, SID Int. Symp. Dig. Tech. 38
(2007) 161.