Paper
tetrakis(triphenylphosphine) palladium(0) (Pd(PPh
Journal of Materials Chemistry C
)
3 4
) (P&H tech using methylene chloride/hexane as an eluent. A white powder
Co.) were also used as received. The general analysis method for was obtained after vacuum train sublimation.
9
1
the synthesized compounds is described in a previous study.
Yield 32%, H NMR (400 MHz, CDCl ): d 8.19–8.13 (m, 2H),
3
8.08 (t, 1H, J = 1.60 Hz), 7.87 (d, 2H, J = 2.00 Hz), 7.84–7.79
(
m, 2H), 7.75–7.74 (m, 2H), 7.72–7.69 (m, 4H), 7.61 (d, 1H,
Synthesis
J = 7.80 Hz), 7.58–7.54 (m, 2H), 7.48–7.43 (m, 6H), 7.37 (t, 2H)
1
3
DBTTP1 was synthesized according to the method reported in the
3
C NMR (400 MHz, CDCl ): d 142.65, 142.23, 141.91, 141.43,
1
4
literature and the synthetic scheme of DBTTP2 is represented in 141.29, 139.76, 138.86, 137.03, 136.51, 136.00, 129.58, 129.07,
Scheme 1.
127.78, 127.58, 127.52, 127.16, 127.04, 125.60, 125.45, 125.37,
0
0 0 00 0 0 0 00
+
5
-Bromo-1,1 :3 ,1 -terphenyl (1). 5 -Bromo-1,1 :3 ,1 -terphenyl 124.62, 122.84, 121.96, 120.83 MS (FAB) m/z 489 [(M + H) ].
15
was synthesized according to the literature method.
Elemental analysis (calculated for C H S): C, 88.49; H, 4.95;
36 24
0
0
00
0
[
1,1 :3 ,1 -Terphenyl]-5 -ylboronic acid (2). Compound 1 (5 g, S, 6.56%. Found: C, 88.33; H, 4.91; S, 6.60%.
16.17 mmol) was added to dry tetrahydrofuran (60 ml) and the
Device fabrication and measurements. Devices fabricated in
solution was stirred at ꢀ78 1C. Then, 2.5 M n-BuLi (7.7 ml) was this work were grown on an indium tin oxide (ITO, 120 nm)
added and triethyl borate (3.30 ml, 19.40 mmol) was added substrate cleaned using deionized water and 2-propanol. After
to the reaction mixture after 2 h. The resulting solution was drying and ultraviolet-ozone treatment for 10 min, poly-
stirred for 24 h under a nitrogen atmosphere and then the (3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS,
mixture was quenched with 2 M HCl solution. The solution was 60 nm) was spin-coated followed by vacuum evaporation
0
extracted with ethyl acetate and distilled water (DW). The of 4,4 -cyclohexylidenebis[N,N-bis(4-methylphenyl)aniline] (TAPC,
organic layer was dried over anhydrous MgSO
4
and evaporated 20 nm), 1,3-bis(N-carbazolyl)benzene (mCP, 10 nm), host:4CzIPN
0
0
00
in vacuo to give a crude product. The synthesized [1,1 :3 ,1 - (25 nm), diphenylphosphine oxide-4-(triphenylsilyl)phenyl (TSPO1,
0
00
terphenyl]-5 -ylboronic acid was used in the next reaction without 5 nm), 2,2,2 -(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole)
further purification. A white powder was obtained as a product (TPBi) (30 nm), LiF(1 nm), and Al(200 nm). 4CzIPN was doped at
(
4.3 g, yield: 97%).
-(3-Bromophenyl)dibenzo[b,d]thiophene (3). 4-(3-Bromo- and luminance data were collected by sweeping the voltage of the
phenyl)dibenzo[b,d]thiophene was synthesized according to device. Electrical and optical performances were gathered using a
doping concentrations of 3, 10, and 15%. Current density, voltage,
4
1
6
the method described in the literature.
Keithley 2400 source measurement unit and a CS 1000 spectro-
-(5 -Phenyl-[1,1 :3 ,1 -terphenyl]-3-yl)dibenzo[b,d]thiophene radiometer. Lifetime measurement of the device was performed at
DBTTP2). Compound 2 (0.2 g, 0.59 mmol), compound 3 (0.19 g, an initial luminance of 1000 cd m in a constant current mode
.71 mmol), and K CO (0.24 g, 1.70 mmol) were dissolved in using a lifetime test system equipped with a photodiode to
0
0
0
00
4
ꢀ2
(
0
2
3
tetrahydrofuran (100 ml) and DW (20 ml) by bubbling with monitor the luminance change during the lifetime test.
nitrogen for 30 min. Pd(PPh (0.2 g, 0.18 mmol) was added to
3 4
)
the solution and the resulting solution was refluxed for 24 h
under a nitrogen atmosphere. The mixture was diluted with
ethyl acetate and washed with DW. The organic layer was dried
Results and discussion
4
over anhydrous MgSO and evaporated in vacuo to give a crude It is important to apply high triplet energy and chemically
product. The extract was evaporated to dryness, affording a white stable host materials for stable operation of the TADF OLEDs.
solid, which was further purified by column chromatography At least, the triplet energy of the TADF host material should be
Scheme 1 Synthetic scheme of DBTTP2 and chemical structure of DBTTP1.
J. Mater. Chem. C
This journal is ©The Royal Society of Chemistry 2015