S.M. Kim et al. / Dyes and Pigments 125 (2016) 274e281
275
host materials to improve the lifetime of the blue PHOLEDs. A
lifetime of 303 h up to 70% of initial luminance at an initial lumi-
nance of 1000 cd/m2 was demonstrated in the 3Cz-DBT device and
it was longer than that of mCBP device. This work is the first
demonstration of high triplet energy host materials which can
exhibit longer lifetime than mCBP.
mixture was diluted with methylene chloride and washed with
water. The organic layer was dried over anhydrous MgSO4 and
evaporated in vacuo to give the crude product. The crude product
was purified by recrystallization using toluene. The product was
obtained as white powder.
Yield 73% (0.45 g), Tg 145 ꢀC, 1H NMR (400 MHz, DMSO):
d
8.83e8.29 (m, 4H), 7.94 (s, 2H), 7.53e7.36 (m, 8H), 7.29 (t, 2H,
2. Experimental
J ¼ 7.2 Hz), 7.19e7.11 (m, 8H), 6.97e6.85 (m, 6H), MS (FAB) m/z
666.83 [(M þ H)þ].
2.1. General information
2.2.4. 2,8-bis(9-phenyl-9H-carbazol-3-yl)dibenzo[b,d]thiophene
(3Cz-DBT)
Palladium(II) acetate (Pd(OAc)2), 2-dicyclohexylphosphino-
20,40,60-triisopropylbiphenyl (XPhos), [1,10-bis(diphenylphosphino)
ferrocene]dichloropalladium(II) (Pd(dppf)Cl2) and tetrakis(-
triphenylphosphine)palladium(0) ((Pd(PPh3)4) were purchased
from P&H tech Co. 1-Bromo-9H-carbazole, 4-chloro-9H-carbazole,
sodium sulfate and iodobenzene were supplied from Sigma Aldrich
Co. Copper, 9-phenyl-2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-
Synthetic process and reaction materials of 3Cz-DBT was the
same as that of 1Cz-DBT except for starting material of 9-phenyl-3-
(4,4,5,5-tetrameth-yl-1,3,2-dioxaborolan-2-yl)-9H-carbazole.
Yield 83% (1.3 g), Tg 150 ꢀC, 1H NMR (400 MHz, DMSO):
d 9.00 (s,
2H), 8.81 (s, 2H), 8.42e8.40 (d, 2H, J ¼ 7.6 HZ), 8.16e8.14 (d, 2H, J ¼ 8
HZ), 8.01e7.99 (d, 4H, J ¼ 8.8 HZ), 7.75e7.67 (m, 8H), 7.59e7.56 (t,
yl)-9H-carbazole
and
9-phenyl-3-(4,4,5,5-tetramethyl-1,3,2-
2H, J ¼ 7.2 HZ), 7.53e7.41 (m, 6H), 7.36e7.32 (t, 2H, J ¼ 7.2 HZ), 13
C
dioxaborolan-2-yl)-9H-carbazole were supplied from Sun fine
global Co. was used without further purification. Sodium hydrox-
ide, potassium carbonate, tetrahydrofuran, ethanol and toluene
were products of Duksan Sci. Co.
NMR (100 MHZ, DMSO): d 140.65, 139.67, 137.69, 137.44, 136.79,
135.95, 132.21, 130.13, 127.65, 126.56, 126.38, 126.10, 125.55, 123.42,
123.33, 122.90, 120.76, 120.09, 118.86, 109.93, 109.67, MS (FAB) m/z
666.83 [(M þ H)þ].
2.2. Synthesis
2.2.5. 4-Chloro-9-phenyl-9H-carbazole
4-Chloro-9H-carbazole (5.0 g, 24.9 mmol), iodobenzene (15.2 g,
74.7 mmol), copper (0.32 g, 5.0 mmol), K2CO3 (6.9 g, 49.8 mmol)
and Na2SO4 (7.1 g, 49.8 mmol) were dissolved in nitrobenzene
(100 ml) under nitrogen atmosphere. The reaction mixture was
stirred and refluxed for 12 h. The mixture evaporated in vacuo to
give the crude product. The crude product was purified by column
chromatography on silica gel using ethyl acetate/n-hexane. The
product was obtained as white powder. (4.5 g, Yield 65%).
2.2.1. 2,8-Bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)dibenzo
[b,d]thiophene
2,8-Dibromodibenzo[b,d]thiophene (3.0 g, 8.8 mmol), bis(pina-
colato)diboron (6.7 g, 26.3 mmol), potassium acetate (4.3 g,
44.0 mmol) and Pd(dppf)Cl2 (0.72 g, 0.88 mmol) were put into 1,4-
dioxane (100 ml) under a nitrogen atmosphere. The reaction
mixture was stirred and refluxed for 4 h. The reaction mixture was
celite filtered, diluted with ethyl acetate, and washed with water.
The organic layer was dried over anhydrous MgSO4 and evaporated
in vacuo to give the crude product. The crude product was purified
by column chromatography on silica gel using ethyl acetate/n-
hexane. The product was obtained as white powder (2.5 g, Yield
65%).
1H NMR (400 MHZ, DMSO):
d
8.53 (d,1H, J ¼ 8.0HZ), 7.67 (m, 2H),
7.56 (m, 3H), 7.48 (t, 1H, J ¼ 8.4HZ), 7.40 (m, 1H), 7.33 (m, 3H), 7.28
(d, 1H, J ¼ 8.0HZ). MS (APIþ) m/z: 277.1 [(M þ H)þ].
2.2.6. 2,8-bis(9-phenyl-9H-carbazol-4-yl)dibenzo[b,d]thiophene
(4Cz-DBT)
1H NMR (400 MHZ, DMSO):
7.75 (d, 2H, J ¼ 8.4HZ), 1.33 (s, 24H).
d
8.56 (s, 2H), 8.03 (d, 2H, J ¼ 8.0HZ),
2,8-Bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)dibenzo
[b,d]thiophene (0.72 g, 1.65 mmol), 4-chloro-9-phenyl-9H-carba-
zole (0.92 g, 3.3 mmol), XPhos (0.16 g, 0.33 mmol), K2CO3 (0.91 g,
3.7 mmol) and Pd(OAc)2 (0.04 g, 0.17 mmol) were dissolved in
toluene (30 ml), ethanol (10 ml) and water (10 ml) under nitrogen
atmosphere. The reaction mixture was stirred and refluxed for 4 h.
The reaction mixture was diluted with methylene chloride and
washed with water. The organic layer was dried over anhydrous
MgSO4 and evaporated in vacuo to give the crude product. The
crude product was purified by column chromatography on silica gel
using ethyl acetate/n-hexane. The product was obtained as white
powder.
2.2.2. 1-Bromo-9-phenyl-9H-carbazole
1-Bromo-9H-carbazole (20.0 g, 81.3 mmol), iodobenzene
(49.7 g, 243.8 mmol), copper (2.6 g, 40.6 mmol), K2CO3 (33.6 g,
243.8 mmol) and Na2SO4 (34.6 g, 243.8 mmol) were vacuum dried
for 1 h, and nitrobenzene (500 ml) was added to the mixture under
a nitrogen atmosphere. The reaction mixture was stirred and
refluxed for 12 h. The mixture was evaporated in vacuo to give the
crude product. The crude product was purified by column chro-
matography on silica gel using ethyl acetate/n-hexane. The product
was obtained as oil. (20.8 g, Yield 79%).
Yield 69% (0.76 g), Tg 162 ꢀC, 1H NMR (400 MHZ, DMSO):
d 8.69
1H NMR (400 MHZ, DMSO):
d
8.27 (d, 1H, J ¼ 7.6 Hz), 8.24 (d, 1H,
(s, 2H), 8.32e8.30 (d, 2H, J ¼ 8.4 HZ), 7.84e7.82 (d, 2H, J ¼ 8.4 HZ),
7.73e7.69 (t. 4H, J ¼ 7.8 HZ), 7.62e7.56 (m, 6H), 7.52e7.48 (t, 2H,
J ¼ 7.8 HZ), 7.44e7.42 (d, 2H, J ¼ 8 HZ), 7.36e7.29 (m, 6H), 7.25e7.23
(d, 2H, J ¼ 7.8 HZ), 7.02e6.98 (t, 2H, J ¼ 8.2), 13C NMR (100 MHz,
J ¼ 7.2 HZ), 7.60e7.55 (m, 4H), 7.45 (d, 2H, J ¼ 8.0 Hz), 7.39 (t, 1H,
J ¼ 7.6 Hz), 7.28 (t, 1H, J ¼ 7.2 Hz), 7.17 (t, 1H, J ¼ 7.6 Hz), 6.97 (d, 1H,
J ¼ 8.0 Hz). MS (APIþ) m/z: 323.8 [(M þ H)þ].
DMSO):
d 140.74, 140.60, 138.50, 137.31, 136.81, 136.62, 135.43,
2.2.3. 2,8-Bis(9-phenyl-9H-carbazol-1-yl)dibenzo[b,d]thiophene
(1Cz-DBT)
130.14, 128.13, 127.93, 127.11, 125.95, 123.16, 122.43, 122.04, 121.79,
121.42, 119.89, 119.57, 109.49, 108.68, MS (FAB) m/z 666.83
[(M þ H)þ].
1-Bromo-9-phenyl-9H-carbazole (1.0 g, 2.8 mmol), 2,8-
bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)dibenzo[b,d]thio-
phene (0.4 g, 0.93 mmol), NaOH (0.15 g, 3.7 mmol) and Pd(PPh3)4
(0.1 g, 0.1 mmol) were put into a round-bottomed flask with THF
(50 ml) and water (30 ml) under a nitrogen atmosphere. The re-
action mixture was stirred and refluxed for 12 h. The reaction
2.3. Device fabrication and measurements
Blue PHOLEDs were fabricated using the sublimed 1Cz-DBT,
3Cz-DBT and 4Cz-DBT. Device stack structure was indium tin oxide