K. He et al. / Organic Electronics 15 (2014) 2942–2949
2947
spectra were measured with a Varian Cray 50 and Perkin–
Elmer LS50B luminescence spectro-meter, respectively.
Cyclic voltammetry was carried out on a CHI 600A electro-
chemical work station in a 0.1 mol/L tetrabutylammonium
0.987 mmol) and sodium carbonate (314 mg, 2.96 mmol)
in 2-ethoxyethanol (15 mL) at 100 °C was stirred vigor-
ously under inert gas atmosphere for 24 h. After cooled
to RT, the mixture was poured into 100 mL distilled water
to form the precipitation. It was collected by vacuum filtra-
tion and washed with plenty of water and a small amount
of ethanol to give a yellow solid. The solid was passed
through a flash silica gel column using THF-DCM(V/V, 1/
4 6
hexafluorophosphate (Bu NPF ) acetonitrile solution at a
1
00 mV/s scan rate under nitrogen protection. A micro-
platinum spar (ø = 0.8 mm), a platinum wire and KCl satu-
rated Hg/HgO were used as the work electrode, counter
electrode and reference electrode, respectively. The ther-
mogravimetric analysis (TGA) was carried out with a NET-
ZSCH STA449 from 25 °C to 600 °C at a 20 °C/min heating
rate under a nitrogen atmosphere.
10) as the eluent to give pale yellow solid (464 mg, yield
1
79.4%). H NMR (CDCl
3
, 400 MHz), d (ppm): 8.71 (d,
J = 5.5 Hz, 1H), 8.30 (t, J = 9.2 Hz, 2H), 8.22 (d, J = 8.3 Hz,
1H), 8.08 (d, J = 8.3 Hz, 1H), 7.90–7.70 (m, 3H), 7.46 (d,
J = 5.5 Hz, 1H), 7.22 (t, J = 6.5 Hz, 1H), 7.03 (t, J = 6.4 Hz,
1H), 6.51 (t, J = 10.6 Hz, 1H), 6.41 (t, J = 10.8 Hz, 1H), 5.82
3.2. Device fabrication and characterization
(
d, J = 8.4 Hz, 1H), 5.51 (d, J = 8.6 Hz, 1H).
(
dfppy) Ir (dipic-FL) was dissolved in chlorobenzene
4 2
with a concentration of 10 mg/mL at room temperature
overnight. The hole-injection layer of poly(ethylenedioxy-
thiophene)/poly(styrene sulfonate) (PEDOT:PSS) was
3.5. Synthesis of dipicMe-FL
0
To a mixture of 2,2 -(9,9-dihexyl-9H-fluorene-2,7-diyl)-
spin-coated on indium tin oxide (ITO) at 3000 rpm in N
atmosphere. Then the emitter layer was prepared by
spin-coating onto the PEDOT:PSS layer at 1500 rpm in N
2
bis(4,4,5,5-tetramethyl-1,3,2-di-oxaborolane)
0.093 mmol), picMe-Br (106 mg, 0.47 mmol), and tetrakis
(triphenylphosphine) palladium [Pd(PPh ] (6 mg) was
(60 mg,
2
3 4
)
atmosphere. Finally, 30 nm electronic-injection layer of
TPBi, 1 nm cathode of LiF and 150 nm capping layer of alu-
minum were successively deposited on the top of emitting
layer through a shadow mask in vacuum. The fabricated
added a degassed mixture of DMA (8 mL) and potassium
carbonate (129 mg, 0.93 mmol). The mixture was stirred
at 80 °C for 12 h under the protection of nitrogen. After
cooled to RT, the mixture was poured into 60 mL distilled
water. It was extracted with DCM (3 ꢂ 20 mL) and the
combined organic layer was dried over anhydrous magne-
sium sulfate. The solvent was removed off by rotary evap-
oration and the residue was passed through a flash silica
SEL devices have
a
configuration of ITO/PEDOT:PSS
(dipic-FL):TCTA (10 wt%) (50 nm)/TPBi
30 nm)/LiF (1 nm)/Al (150 nm). The emitting layer con-
Ir (dipic-FL) dopant and TCTA host
(
4 2
40 nm)/(dfppy) Ir
(
sisted of (dfppy)
4 2
matrix. The dopant concentration was 10 wt%. EL spectra
were recorded with an Insta-Spec IV CCD system (Oriel).
Luminance was measured with a Si photodiode and cali-
brated by using a PR-705 spectrascan spectrophotometer
gel column with EA–DCM (V/V, 1/10) as the eluent to give
1
colorless solid (40 mg, yield 66%).
3
H NMR (CDCl ,
400 MHz, TMS), d (ppm): 9.04 (s, 2H), 8.25 (d, J = 8.0 Hz,
2H), 8.10 (d, J = 8.0 Hz, 2H), 7.88 (d, J = 7.8 Hz, 2H), 7.65
(d, J = 7.8 Hz, 2H), 7.60 (s, 2H), 4.06 (s, 6H), 2.10–2.00 (m,
(
Photo Research).
4
H), 1.38–0.94 (m, 24H), 0.78 (t, J = 6.8 Hz, 6H), MALDI-
3.3. General information
TOF MS (m/z) for C43 , Calcd: 660.40, Found,
52 2 4
H N O
+
6
60.43 [M], 683.41 [M + Na].
All solvents were carefully dried and distilled prior to
use. Commercially available reagents were used without
further purification unless otherwise stated. All reactions
were performed under a nitrogen atmosphere and were
monitored by thin-layer chromatography (TLC). Flash col-
umn chromatography and preparative TLC were carried
4 2
3.6. Synthesis of (dfppy) Ir (dipic-FL)
0
To a mixture of 2,2 -(9,9-dihexyl-9H-fluorene-2,7-diyl)-
bis(4,4,5,5-tetramethyl-1,3,2-di
0.078 mmol), (dfppy) Ir(pic-Br) (135 mg, 0.18 mmol), and
Pd(PPh (11 mg) was added a degassed mixture of THF
oxaborolane) (50 mg,
2
out using silica gel as absorbent from Merck (200–
3 4
)
0
3
00 mesh).
2,2 -(9,9-dioctyl-9H-fluorene-2,7-diyl)-
(10 mL), anhydrous ethanol (1 mL) and 2 M potassium car-
bonate aqueous solution (1 mL). The mixture was refluxed
for 24 h under the protection of nitrogen. After cooled to
RT, the mixture was poured into 100 mL distilled water.
It was extracted with DCM (3 ꢂ 30 mL) and the combined
organic layer was dried over anhydrous magnesium sul-
fate. The solvent was removed off by rotary evaporation
and the residue was passed through a flash silica gel col-
bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolane) (4) [33] and
dfppy) Ir(pic) [32] were synthesized accord- ing to the
described procedures before.
(
2
2
3.4. Synthesis of (dfppy) Ir(pic-Br)
To a mixture of IrCl
water (6 mL) was added 2,4-difluoropyphenylpyridine
752 mg, 3.95 mmol) and 2-ethoxyethanol (18 mL). The
3 2
ꢁH O (500 mg, 1.58 mmol) and
umn with THF–DCM (V/V, 1/5) as the eluent to give pale
yellow solid (76 mg, yield 55%).
1
(
3
H NMR (CDCl ,
mixture was stirred for 24 h at 100 °C in nitrogen atmo-
sphere. After cooled to RT, the colored precipitate was fil-
tered off, washed with water and hexane, respectively. A
400 MHz, TMS), d (ppm): 8.39 (d, J = 8.1 Hz, 2H), 8.33 (d,
J = 8.5 Hz, 2H), 8.28 (d, J = 8.4 Hz, 2H), 8.81 (d, J = 5.2 Hz,
2H), 8.19 (d, J = 8.0 Hz, 2H), 8.02 (s, 2H), 8.00–7.70 (m,
6H), 7.58 (d, J = 5.3 Hz, 2H), 7.39 (d, J = 7.8 Hz, 2H), 7.30–
7.20 (m, 4H), 7.01 (t, J = 6.2 Hz, 2H), 6.53 (t, J = 10.3 Hz,
2H), 6.43 (t, J = 10.0 Hz, 2H), 5.93 (d, J = 6.7 Hz, 2H), 5.61
yellow solid of dimer of [(dfppy)
2
IrCl]
0.742 g, yield 77.3%). Then a mixture of the dimer
400 mg, 0.329 mmol), 5-bromopicolinic acid (200 mg,
2
was obtained
(
(