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Ar-CH–naphthalene), 7.24–7.21 (d, 2H, Ar-CH–naphthalene),
7.18–7.16 (d, 2H, Ar-CH–naphthalene), 7.16–7.14 (d, 2H,
Ar-CH–naphthalene), 7.12–7.10(s, 2H, Ar-CH–benzene),
7.10–7.08(d, 2H, Ar-CH–benzene), 7.08–7.06(d, 1H,
Ar-CH–benzene), 7.06–7.04(d, 2H, Ar-CH–benzene), 6.99–
6.97 (d, 2H, Ar-CH–fluorene), 6.96–6.94(d, 1H, Ar-CH–
benzene), 6.92–6.91(d, 2H, Ar-CH–benzene), 6.90–6.88(d,
1H, Ar-CH–benzene), 6.89–6.87 (d, 1H, Ar-CH–naphtha-
lene), 6.85–6.83(s, 1H, Ar-CH–benzene), 6.73–6.71 (s,
1H, Ar-CH–benzene), 6.63–6.62 (d, 1H, Ar-CH–benzene).
13C NMR (CDCl3) d 151.7, 148.0, 147.9, 147.7, 147.5,
146.7, 145.7, 145.1, 142.7, 142.1, 137.2, 135.5, 134.4,
131.8, 130.8, 130.1, 129.5, 129.3, 129.1, 128.8, 128.7,
127.9, 127.8, 127.6, 127.1, 127.0, 126.9, 126.3, 126.2,
125.7, 124.6, 124.5, 124.2, 124.1, 124.0, 123.8, 123.5,
123.3, 122.6, 121.8, 121.6, 120.4, 120.0, 119.4, 117.2,
77.4, 77.2, 76.9, 66.4.
2.3. OLED fabrication
A basic device configuration of indium tin oxide(ITO,
150 nm)/N,N0-diphenyl-N,N0-bis-[4-(phenyl-m-tolyl-ami-
no)-phenyl]-biphenyl-4,40-diamine (DNTPD, 60 nm)/N,N0-
di(1-naphthyl)-N,N0-diphenylbenzidine (
a-NPB, 30 nm)/2-
methyl-9,10-di(2-naphthyl) anthracene (MADN): dopant
(30 nm, x%)/tris(8-hydroxyquinoline)aluminum (Alq3,
20 nm)/LiF (1 nm)/Al (200 nm) was used for device fabrica-
tion. All organic materials except for dopants were depos-
ited at a deposition rate of 1 Å/s. The doping concentration
of the dopant materials was varied at 3, 5 and 7%. The de-
vices were encapsulated with a glass lid and a CaO getter
after cathode deposition. Current density–voltage-lumi-
nance and electroluminescence characteristics of the blue
fluorescent OLEDs were measured with a Keithley 2400
source measurement unit and CS 1000 spectroradiometer.
Lifetime measurement of the blue OLEDs was carried out at
a luminance of 5000 cdmꢀ2 at constant current mode.
N,N0-Diphenyl-N,N0-di-m-tolyl-SFBF-5,9-diamine (BD-
6MDPA). Yield 64%. Mp 248 °C. 1H NMR (500 MHz, CDCl3)
d 8.77–8.75 (d, J = 8.47 Hz, 1H, Ar-CH–naphthalene), 8.22–
8.20 (d, J = 8.53 Hz, 1H, Ar-CH–naphthalene), 8.02–8.01 (d,
J = 8.45 Hz, 1H, Ar-CH–benzene), 7.69–7.67 (d, J = 7.60 Hz,
2H, Ar-CH–fluorene), 7.60–7.59 (t, J = 8.00 Hz, 1H, Ar-CH–
naphthalene), 7.39–7.38 (t, J = 7.57 Hz, 1H, Ar-CH–naph-
thalene), 7.28–7.27 (t, J = 7.90 Hz, 2H, Ar-CH–fluorene),
7.12–7.10(s, 2H, Ar-CH–benzene), 7.12–7.10(t, 4H,
Ar-CH–benzene), 7.10–7.08 (d, 2H, Ar-CH–fluorene), 7.04–
7.02 (d, 2H, Ar-CH–benzene), 6.96–6.94(d, 1H, Ar-CH–ben-
zene), 6.90–6.89(t, 4H, Ar-CH–benzene), 6.89–6.87 (d, 2H,
Ar-CH–naphthalene), 6.80–6.78 (d, 2H, Ar-CH–benzene),
6.74–6.72 (d, 2H, Ar-CH–benzene), 6.71–6.68 (d, 2H, Ar-
CH–benzene), 6.62–6.60 (d, J = 7.92 Hz, 1H, Ar-CH–ben-
zene), 6.57–6.57 (s, 1H, Ar-CH–benzene), 2.08–2.09 (s,
6H, Ar-CH3). 13C NMR (CDCl3) d 151.5, 148.1, 147.9,
147.8, 147.5, 147.4, 146.8, 142.7, 142.1, 139.0, 138.8,
136.9, 135.4, 131.9, 130.8, 129.2, 129.0, 128.8, 127.9,
127.8, 126.9, 126.1, 125.7, 124.5, 124.4, 124.1, 123.8,
123.6, 123.3, 123.0, 122.5, 122.1, 121.4, 121.3, 121.1,
120.4, 119.2, 118.6, 77.4, 77.2, 76.9, 66.4, 21.5, 21.4.
N,N0-Diphenyl-N,N0-bis(4-(trimethylsilyl)phenyl)-SFBF-
5,9-diamine (BD-6TMSA). Yield 60%. Mp 256 °C. 1H NMR
(500 MHz, CDCl3) d 8.78–8.76 (d, J = 8.50 Hz, 1H, Ar-CH–
naphthalene), 8.24–8.23 (d, J = 8.53 Hz, 1H, Ar-CH–naph-
thalene), 8.02–8.00 (d, J = 8.42 Hz, 1H, Ar-CH–benzene),
7.69–7.67 (d, J = 7.60 Hz, 2H, Ar-CH–fluorene), 7.61–7.59
(t, J = 7.38 Hz, 1H, Ar-CH–naphthalene), 7.39–7.38 (t,
J = 7.70 Hz, 1H, Ar-CH–naphthalene), 7.28–7.27 (t, 2H,
Ar-CH–fluorene), 7.24–7.22(d, 2H, Ar-CH–benzene),
7.12–7.10(s, 2H, Ar-CH–benzene), 7.12–7.10(t, 4H,
Ar-CH–benzene), 7.10–7.08 (d, 2H, Ar-CH–fluorene), 6.96–
6.94(d, 2H, Ar-CH–benzene), 6.90–6.89(d, 2H, Ar-CH–ben-
zene), 6.89–6.87 (d, 1H, Ar-CH–naphthalene), 6.82–6.81
(d, 4H, Ar-CH–benzene), 6.71–6.69 (s, 1H, Ar-CH–ben-
zene), 6.567–6.56 (s, 1H, Ar-CH–benzene), 0.21–0.20 (s,
9H Ar-Si–(CH3)3), 0.16–0.15 (s, 9H Ar-Si–(CH3)3). 13C
NMR (CDCl3) d 151.7, 148.5, 148.1, 148.0, 147.8, 147.6,
147.3, 146.6, 142.4, 142.1, 137.3, 135.6, 134.3, 134.2,
133.7, 132.0, 131.8, 130.8, 129.2, 129.1, 127.9, 127.8,
127.0, 126.2, 125.7, 124.4, 124.3, 123.9, 123.8, 123.4,
123.1, 122.7, 121.9, 121.4, 120.3, 120.0, 119.9, 77.4,
77.2, 76.9, 66.4.
3. Results and discussion
3.1. Synthesis and characterization
The key intermediate in this synthesis is the introduc-
tion of diarylamine substituents into the 5- and 9-position
of the SFBF by amination reactions, to tune the electro-
optical properties of the deep-blue emitting dopant
materials. 5,9-Dibromo- SFBF (1) was prepared by selec-
tive bromination of SFBF via 5-bromo-SFBF using carbon
tetrachloride and chloroform solvent as shown in
Scheme 1. The dopant materials N,N,N0,N0-tetraphenyl-
SFBF-5,9-diamine (BD-6DPA), N,N0-di-(2-naphthyl)-N,N0-
diphenyl-SFBF-5,9-diamine (BD-6NPA), N,N0-diphenyl-
N,N0-dim-tolyl-SFBF-5,9-diamine (BD-6MDPA) and
N,N0-diphenyl-N,N0-bis(4-(trimethylsilyl)phenyl)-SFBF-
5,9-diamine (BD-6TMSA) were prepared by amination
reactions of compounds 1 with diphenylamine, N-phenyl-
2-naphthylamine, 3-methyldiphenylamine and N-phenyl-
4-(trimethylsilyl)aniline in the presence of a palladium
catalyst. The synthetic routes to the four dopant materials
are described in Scheme 1. The chemical structures and
compositions of the resulting precursor and spiro-com-
pounds were characterized by 1H NMR, 13C NMR, FT-IR
and GC–MS.
3.2. Optical properties and energy levels
Table 1 shows the UV–vis absorption and photolumi-
nescence (PL) spectra data of the dopant materials, res-
pectively. The solution absorption maxima of BD-6DPA,
BD-6NPA, BD-6MDPA and BD-6TMSA showed at 407, 411,
408 and 407 nm, respectively, whereas the BD-6 series
showed at 416, 421, 416 and 413 nm in film. The emission
maximum of BD-6DPA, BD-6NPA, BD-6MDPA and BD-
6TMSA were located at 478, 464, 468 and 459 nm in solu-
tion, respectively, whereas the BD-6 series showed an
absorption maximum at 484, 491, 487 and 484 nm in film.
The introduction of a diphenylamine group to both the 5-
and 9-positions in SFBF caused a significant red-shift in