Low-Voltage-Driven Electrophosphorescence
FULL PAPER
m/z (%): 726 (100) [M]+; elemental analysis calcd (%) for
C36H26Br2O3P2: C 59.37, H 3.60, O 6.59; found: C 59.46, H 3.68, O 6.77.
metal-oxide-based acceptors, was directly deposited onto the ITO sub-
strate for each sample. After the deposition of Cs2CO3, the samples were
transferred into a metal chamber and suffered from a vacuum break,
owing to the change of the shadow masks to determine the active area.
The luminance–current–voltage characteristics of the samples were meas-
ured on a PR650 spectrascan spectrometer with a Keithley 2400 pro-
grammable voltage–current source. All of the samples were measured di-
rectly after fabrication without encapsulation in air at RT.
General procedure for the Ullmann reactions: A mixture of the bromide
(1 mmol), the carbazole (3 equiv), K2CO3 (3 equiv), CuI (0.1 equiv), and
18-crown-6 (0.05 equiv, 0.05 mmol) in 1,3-dimethyl-2-imidazolidinone
(DMI, 10 mL) was warmed to 1908C and stirred for 24 h. Then, the reac-
tion was quenched with an aqueous solution of HCl (2m, 10 mL) and ex-
tracted with CH2Cl2 (3ꢁ10 mL). The organic layer was dried with anhy-
dride Na2SO4. The solvent was removed in vacuo and the residue was pu-
rified by column chromatography on silica gel (petroleum ether/EtOAc).
9-[4-[2-(Diphenylphosphinoyl)-phenoxy]-phenyl]-9H-carbazole (DPES-
POCz): White powder; 246 mg (46% yield from DPESPOBr); 1H NMR
(TMS, CDCl3, 400 MHz): d=8.152 (d, J=8.0 Hz, 2H), 8.095 (qd, 1J=
7.2 Hz, 2J=12.8 Hz, 3J=1.6 Hz, 1H), 7.836 (q, 1J=7.0 Hz, 2J=12.6 Hz,
4H), 7.599 (t, J=7.6 Hz, 1H), 7.514 (td, 1J=7.4 Hz, 2J=1.2 Hz, 2H),
7.499–7.403 (m, 6H), 7.386–7.267 (m, 7H), 7.009 (q, 1J=5.0 Hz, 2J=
8.2 Hz, 1H), 6.812 ppm (d, J=8.8 Hz, 2H); MS (ESI): m/z (%): 535
(100) [M]+; elemental analysis calcd (%) for C36H26NO2P: C 80.73,
H 4.89, N 2.62, O 5.97; found: C 80.91, H 4.95, N 2.74, O 6.14.
Acknowledgements
This work was financially supported by the National Key Basic Research
and Development Program of China (2010CB327701), the NSFC
(50903028, 61176020, and 60977024), the Key Project of the Ministry of
Education (212039), the Developing Program of New Century Excellent
Talents in Heilongjiang Provincial Universities (1252-NCET-005), the Ed-
ucation Bureau of Heilongjiang Province (10td03), and the Supporting
Program of High-Level Talents of the HLJU (2010hdtd08).
9-[4-[4-Carbazol-9-yl-2-(diphenylphosphinoyl)-phenoxy]-phenyl]-9H-car-
bazole (DPESPOCz2): White powder; 175 mg (25% yield from DPE-
POBr2); 1H NMR (TMS, CDCl3, 400 MHz): d=8.211 (dd, 1J=2.6 Hz,
2J=13.0 Hz, 1H), 8.152 (dd, 1J=5.6 Hz, 2J=7.2 Hz, 4H), 7.911 (q, 1J=
6.8 Hz, 2J=12.4 Hz, 4H), 7.762 (dd, 1J=2.4 Hz, 2J=8.8 Hz, 1H), 7.616–
7.486 (m, 6H), 7.488–7.399 (m, 8H), 7.402–7.297 (m, 6H), 7.211 (dd, 1J=
5.4 Hz, 2J=8.6 Hz, 1H), 6.964 ppm (d, J=8.8 Hz, 2H); MS (ESI): m/z
(%): 700 (100) [M]+; elemental analysis calcd (%) for C48H33N2O2P:
C 82.27, H 4.75, N 4.00, O 4.57; found: C 82.39, H 4.76, N 4.15, O 4.81.
[1] a) J. H. Burroughes, D. D. C. Bradley, A. R. Brown, R. N. Marks, K.
d) C. D. Mꢄller, A. Falcou, N. Reckefuss, M. Rojahn, V. Wiederhirn,
P. Rudati, H. Frohne, O. Nuyken, H. Becker, K. Meerholz, Nature
9-[4-(2,4-Bis-carbazol-9-yl-phenoxy)-3-(diphenylphosphinoyl)-phenyl]-
9H-carbazole (DPESPOCz3): White powder; 260 mg (30% yield from
DPESPOBr3); 1H NMR (TMS, CDCl3, 400 MHz): d=8.346 (dd, 1J=
2.0 Hz, 2J=12.8 Hz, 1H), 8.213 (d, J=7.6 Hz, 2H), 8.164 (t, J=7.6 Hz,
4H), 7.824 (dd, 1J=2.2 Hz, 2J=8.6 Hz, 1H), 7.694 (d, J=1.6 Hz, 1H),
7.555–7.296 (m, 25H), 7.265 (s, 1H), 7.187–7.088 (m, 4H), 6.957 ppm (d,
J=8.8 Hz, 2H); MS (ESI): m/z (%): 865 (100) [M]+; elemental analysis
calcd (%) for C60H40N3O2P: C 83.22, H 4.66, N 4.85, O 3.70; found:
C 83.34, H 4.69, N 4.98, O 3.86.
[2] a) G. Li, V. Shrotriya, J. Huang, Y. Yao, T. Moriarty, K. Emery, Y.
[5] W. Huang, B. Mi, Z. Gao, Organic Electronics, 1st ed., Science
Press, Beijing, 2011.
9-[3-(Diphenylphosphinoyl)-4-[2-(diphenylphosphinoyl)-phenoxy]-
phenyl]-9H-carbazole (DPEPOCz): White powder; 294 mg (40% yield
from DPEPOBr); 1H NMR (TMS, CDCl3, 400 MHz): d=8.103 (d, J=
7.6 Hz, 2H), 7.890–7.634 (m, 10H), 7.610–7.246 (m, 20H), 7.208 (d, J=
7.4 Hz, 1H), 6.372–6.269 ppm (m, 2H); MS (ESI): m/z (%): 735 (100)
[M]+; elemental analysis calcd (%) for C48H35NO3P2: C 78.36, H 4.79,
N 1.90, O 6.52; found: C 78.42, H 4.85, N 2.07, O 6.68.
[6] M. A. Baldo, M. E. Thompson, S. R. Forrest, Nature 2000, 403, 750.
[8] a) R. J. Holmes, S. R. Forrest, Y.-J. Tung, R. C. Kwong, J. J. Brown,
Tokito, T. Iijima, Y. Suzuri, H. Kita, T. Tsuzuki, F. Sato, Appl. Phys.
b) M. A. Baldo, D. F. OꢃBrien, Y. You, A. Shoustikov, S. Sibley,
M. E. Thompson, S. R. Forrest, Nature 1998, 395, 151.
[10] a) J. Kalinowski, W. Stampor, J. Mecedilzdotyk, M. Cocchi, D. Virgi-
li, V. Fattori, P. Di Marco, Phys. Rev. B 2002, 66, 235321; b) S. Rein-
eke, K. Walzer, K. Leo, Phys. Rev. B 2007, 75, 125328; c) N. C. Gie-
bink, S. R. Forrest, Phys. Rev. B 2008, 77, 235215.
[11] M. A. Baldo, S. Lamansky, P. E. Burrows, M. E. Thompson, S. R.
[12] C. Adachi, R. C. Kwong, P. Djurovich, V. Adamovich, M. A. Baldo,
[13] S. Reineke, F. Lindner, G. Schwartz, N. Seidler, K. Walzer, B.
9-[4-[4-Carbazol-9-yl-2-(diphenylphosphinoyl)-phenoxy]-3-(diphenylphos-
phinoyl)-phenyl]-9H-carbazole (DPEPOCz2): White powder; 225 mg
(25% yield from DPEPOBr2); 1H NMR (TMS, CDCl3, 400 MHz): d=
8.119 (d, J=7.6 Hz, 4H), 7.826 (dd, 1J=2.4 Hz, 2J=13.2 Hz, 4H), 7.818–
7.684 (m, 6H), 7.620–7.465 (m, 8H), 7.462–7.352 (m, 10H), 7.350–7.296
(m, 8H), 7.211 (dd, 1J=5.4 Hz, 2J=8.6 Hz, 1H), 6.594 ppm (q, 1J=
5.2 Hz, 2J=8.4 Hz, 2H); MS (ESI): m/z (%): 900 (100) [M]+; elemental
analysis calcd (%) for C60H42N2O3P2: C 79.99, H 4.70, N 3.11, O 5.33;
found: C 80.02, H 4.69, N 3.24, O 5.51.
Gaussian calculations: Computations on the electronic ground state of
the single-molecular compounds in a vacuum were performed by using
Beckeꢃs three-parameter density functional in combination with the non-
local correlation functional of Lee, Yang, and Parr (B3LYP).[19] 6–31G(d)
basis sets were employed. Ground-state geometries in a vacuum were
fully optimized at the B3LYP level. All of the computations were per-
formed by using the Gaussian 03 package.[20]
Device fabrication and testing: Prior to the fabrication of the devices, the
patterned ITO-coated glass substrates were scrubbed and sonicated con-
secutively with acetone, EtOH, and deionized water. All of the organic
layers were thermally deposited under a vacuum (about 4.0ꢁ10ꢀ4 Pa) at
a rate of 1–2 ꢂsꢀ1, which was monitored in situ by a quartz oscillator. To
decrease the ohmic loss, a heavily p-doped layer with MoOx, considering
the low doping efficiency in amorphous organic matrices with transition-
H. Chien, C.-F. Shu, C.-H. Lai, C.-C. Hsieh, K.-W. Wang, P.-T. Chou,
Chem. Eur. J. 2013, 19, 141 – 154
ꢀ 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
153