Synthesis and Properties of Main-Chain Phosphorescent Polymer with Iridium Complex

Article abstract of DOI:10.1134/S1070363219120284

The main-chain phosphorescent polymers, PFCzIr(PhStz) and PFOIr(PhStz) with iridium complex (4-BrPhBt)₂Ir(Pytz), are synthesized by the Suzuki polycondensation, in which the fluorene-carbazole and fluorene segments are used as a polymer backbon

Full text of DOI:10.1134/S1070363219120284

ISSN 1070-3632, Russian Journal of General Chemistry, 2019, Vol. 89, No. 12, pp. 2504–2511. © Pleiades Publishing, Ltd., 2019.
Synthesis and Properties of Main-Chain Phosphorescent Polymer
with Iridium Complex
Ch. Liua, D. Lia, G. Xinga, L. Chena, M. Lina,*, and Q. Linga,**
a Fujian Key Laboratory of Polymer Materials, College of Chemistry and Materials, Fujian Normal University,
Fuzhou, 350007 China
e-mail: *mjlin@fjnu.edu.cn; **qdling@fjnu.edu.cn
Received May 31, 2019; revised December 25, 2019; accepted December 25, 2019
Abstract—The main-chain phosphorescent polymers, PFCzIr(PhStz) and PFOIr(PhStz) with iridium complex
(4-BrPhBt)2Ir(Pytz), are synthesized by the Suzuki polycondensation, in which the fluorene-carbazole and fluo-
rene segments are used as a polymer backbone. The studied photoluminescent and electroluminescent properties
demonstrate good overlap of the emission spectra of poly(fluorene-carbazole) (PFCz) or polyfluorene (PFO) host
and the absorption spectra of the iridium complex guest that meets requirements for the efficient Forster transfer
from the host polymer to the iridium complex in polymers. With the increase of the content of iridium complex,
the host emission intensity decreases, while the guest emission intensity gradually increases. As compared with
PFOIr(PhStz), host-guest system in PFCzIr(PhStz) is more efficient in Forster energy transfer, and the photolu-
minescence and electroluminescence properties are more sound. Among all polymers, PFCzIr(PhStz) 5.0 demon-
strates the best performance in electroluminescence, its fluorescence quantum is 22.74%. The devices fabricated
from PFCzIr(PhStz)5.0 exhibit yellow-red emission with a maximum brightness of 1568 cd/m2 at 14 V, luminous
efficiency and power efficiency reach 6.24 cd/A and 2.45 lm/w.
Keywords: iridium complex, main-chain polymer, phosphorescence, photoluminescence, electroluminescence
DOI: 10.1134/S1070363219120284
INTRODUCTION
green emitting iridium complex (4-BrPhBt)2Ir(Pytz)
guest was introduced into the main chain. A series of
main-chain orange-red phosphorescent polymers with
different guest content were successfully synthesized by
the Suzuki polycondensation, the photoluminescence and
electroluminescence were studied.
Over recent years, polymers with iridium complex
phosphorescent devices became the new generation of
light carriers because of their ultrathin geometry, flex-
ibility, low power consumption, and simple fabrication
process [1–4]. Polymer phosphorescent materials with
excellent solubility can be used as simple devises for spin
coating [5–8]. By introducing iridium complexes in the
main or side chain of phosphorescent polymers by chemi-
cal bonding, the concentration quenching phenomenon
caused by aggregation can be effectively avoided, mean-
while, the phase separation and poor stability problems of
doping-organic light emitting devices under high current
density can be solved [9–11]. Polyfluorene and carbazole
derivatives are used widely in polymer electrolumines-
cence, because they can efficiently enhance excitation by
recombination of an electron and hole, have high triplet
energy level, and also avoid the guest return the triplet
energy to the host [12–14].
EXPERIMENTAL
All reagents and solvents were obtained from com-
mercial suppliers and used without further purification
unless otherwise stated. TLC was performed on G254
silica gel plates purchased from the Qingdao Haiyang
Chemical. Column chromatography was performed using
Sorbent Technologies brand silica gel (200–300 mesh).
1H NMR spectra were measured on a Bruker AVIII-400
NMR spectrometer in CDCl3. UV-Vis absorption spectra
were recorded on a Shimadzu UV-2600 spectrophotom-
eter in CH2Cl2 (1×10–5 M). PL spectra were recorded on
a Shimadzu RF-5301 PC spectrophotometer. Absolute
photoluminescence quantum efficiencies in solid state
were measured on an Edinburgh Instruments FLS920
Inthispaper, blueemittingpolyfluorene–poly(fluorene-
carbazole) was selected as the main chain, and yellow
2504

SYNTHESIS AND PROPERTIES OF MAIN-CHAIN PHOSPHORESCENT POLYMER
2505
H
NH
N
N
H2N NH2
EtOH
N
N
N
HCOOH
CN
C
HN NH2
N
2
1
Br
Br
Br
Cl
Cl
Ir
Ir
24 h,
room temperature
IrCl
3·3H2O
H2N
HS
OHC
Br
+
S
N
N
S
S
N
N
methanol, benzene
, 105q
C, 24 h
2
2
2
3
4
Br
N
Ir
2-ethoxyethanol, Na
2CO3
4
2
+
S
N
N , 120q
C, 12 h
2
N
N
N
2
M1
Fig. 1. Synthetic route to iridium complex M1.
Fluorescence Spectrometer. Cyclic voltammetry measure-
ments were carried out on a CHI600D electrochemical
analyzer using a three-electrode configuration under the
atmosphere of nitrogen. Oxidation potentials were mea-
sured by cyclic voltammetry (CV) in acetonitrile with
Ag/AgCl as a reference electrode.
3×10–4 Pa. Athin layer of LiF (1 nm) depositing onto the
TPBI layer, was followed by depositing an aluminum
layer (120 nm). Finally, the device was encapsulated with
UV-curing glue and exposed to UV light for 10 min in
the glove box. The current–voltage and light intensity
measurements were carried out on a Keithly 2400 source
meter and a PR-655 Spectra Scan Spectrophotometers.
In the fabrication process, indium-tin oxide (ITO)
with a sheet resistance less than 50 Ω was used as the
substrate. It was washed with detergent, deionized water,
acetone, and isopropyl alcohol in sequence. The ITO glass
substrates were dried under nitrogen flow and followed by
oxygen plasma cleaning for 4 min. Then, a 25 nm thick
poly(ethylenedioxythiophene) : poly(styrenesulfonic
acid) (PEDOT:PSS) was spin-coated onto the ITO glass
substrate, and heated at 120°C for 20 min. Upon cooling
down to room temperature the polymer layer was spin-
coated onto the PEDOT:PSS layer from a chlorobenzene
solution (10–20 mg/mL) through a Teflon filter (0.2 μm).
An electron transporting layer, 2,2',2''-(1,3,5-benzeneriyl)-
tris(1-phenyl-1H-benzimidazole) (TPBI), was grown
by thermal evaporation in a chamber under pressure of
Synthesis of iridium complex. The synthetic route to
iridium complex monomer is presented in Fig. 1.
(Pyridine-2-yl)amidrazone (1) [15]. 3.1 g
(2.05 g, 32.8 mmol) and 80% hydrous correction: 2.05 g
(32.8 mmol) of 80% hydrazine hydrous were reacted in
5 mL absolute ethanol under the atmosphere of nitrogen
for 6 h at room temperature. Most of precipitate was fil-
tered off. The product was washed with petroleum ether
repeatedly and dried under vacuum. Yield 75%. 1H NMR
spectrum, δ, ppm: 8.51 d.d.d (1H, pyridine), 8.00 d.t (1H,
pyridine), 7.74–7.63 m (1H, pyridine), 7.28–7.25 m (1H,
pyridine), 5.27 s (2H, NH2), 4.57 s (2H, NH2).
2-(1H-1,2,4-Triazol-5-yl) pyridine (2) [16]. 3.67 g
(27 mmol) of (pyridine-2-yl)amidrazone (1) was dis-
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 89 No. 12 2019

2506
LIU et al.
Br
C8H17
N
N
N
C8H17
C8H17
Ir
+
+
or
N
S
N
Br
Br
Br
N
Br
B
O
O
B
O
O
2
M2
M4
M1
M3
Pd(PPh3)4
K2CO3(aq.), toluene
TBAI
(1)
(2)
B(OH)2
Br
n
S
m
N
N
Ir
N
N
N
N
S
PFOIr(PhStz) 2.5 M1/(M1 + M2 + M3) = 2.5/100
PFOIr(PhStz) 5.0 M1/(M1 + M2 + M3) = 5.0/100
PFOIr(PhStz) 10 M1/(M1 + M2 + M3) = 10/100
or
n
N
N
S
m
N
N
Ir
N
N
N
S
PFCzIr(PhStz) 2.5 M1/(M1 + M2 + M4) = 2.5/100
PFCzIr(PhStz) 5.0 M1/(M1 + M2 + M4) = 5.0/100
Fig. 2. Synthetic routes to polymers PFOIr(PhStz) and PFCzIr(PhStz).
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 89 No. 12 2019

SYNTHESIS AND PROPERTIES OF MAIN-CHAIN PHOSPHORESCENT POLYMER
2507
Table 1. The feed amount of monomers, molecular weight and the distribution of polymers
Polymer
M1, mmol
0.005
M2, mmol
0.1
M3, mmol
M4, mmol
Yield, %
Mn×104
1.31
PDI
1.74
1.77
1.77
1.41
1.47
PFOIr(PhStz) 2.5
PFOIr(PhStz) 5.0
PFOIr(PhStz) 10
PFCzIr(PhStz) 2.5
PFCzIr(PhStz) 5.0
0.095
0.090
0.080
-
-
32
39
47
36
43
0.010
0.1
-
1.63
0.020
0.1
-
1.43
0.005
0.1
0.095
0.090
2.39
0.010
0.1
-
2.17
solved in 10 mL of formic acid upon cooling on an ice
bath, and 30 mL of formic acid were dropped slowly
into a flask. The mixture was stirred at 115°C for 2 h.
After cooling down to room temperature, the solution
was poured into 50% NaOH to adjust pH 6–7, extracted
with ethyl acetate and saturated salt solution 3 times. The
combined organic layers were dried over MgSO4, the
white precipitate was recrystallized with CHCl3. Yield
the atmosphere of nitrogen. After cooling down to room
temperature, the precipitate was filtered off and washed
with methanol, ether and hexane consequently. The
crude product was flash chromatographed on a silica
column with dichloromethane mobile phase to afford
brown-yellow powdery (4-BrPhBt)2Ir(Pytz)(M1). Yield
1
61%. H NMR spectrum, δ, ppm: 8.65 d (1H, N=CH),
8.29 s (1H, pyridine), 8.01–8.03 m (3H, pyridine), 7.85 t
(2H, benzothiazole), 7.75 d (2H, phenyl), 7.66–7.68 m
(4H, phenyl), 7.53 d.d (4H, benzothiazole), 7.36 t (2H,
benzothiazole).
1
60%. H NMR spectrum, δ, ppm: 13.12 s (1H, NH),
8.83–8.71 m (1H, N=CH), 8.26 d (1H, pyridine), 8.14 s
(1H, pyridine), 7.91 t.d (1H, pyridine), 7.51–7.38 m
(1H). 13C NMR spectrum, δ, ppm: 155.01, 150.47, 149.47,
146.67, 137.85, 125.01, 122.03.
Synthesis of polymers. Synthetic routes to the poly-
mers are presented in Fig. 2.
2-(4-Bromophenyl)benzo[d]thiazole (3)[17]. 1.27 g
(6.87 mmol) of 3-bromobenzaldehyde and 1.50 g
(12 mmol) of 2-amino phenyl mercaptan were added to
the mixed solvent of methanol and benzene. The mixture
was stirred at room temperature in nitrogen atmosphere
for 24 h. Upon completion of the reaction the solvent
was removed. The solid was recrystallized three times
General procedure of the Suzuki polycondensation,
using PFOIr(PhStz)2.5 as an example. To a mixture
of (4-BrPhBt)2Ir(Pytz) (M1, 4.2 mg, 0.005 mmol)
with 2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-
2-yl)-9,9-dioctylfluorene (M2, 64.25 mg, 0.1 mmol),
9,9-dioctyl-2,7-dibromofluorene (M3, 52.1 mg,
0.095 mmol), 46 mg tetrabutylammonium iodide (TBAI),
5 mg tetrakis(triphenylphosphine)palladium, and toluene
(3 mL), saturated potassium carbonate solution (2 mL)
was added. The mixture was heated to 110°C and stirred
for 48 h in the atmosphere of argon [18]. Then the
polymer was endcapped by adding benzeneboronic acid
(0.12 g, 1.0 mmol) followed by stirring for 12 h, addition
of bromobenzene (0.10 mL, 1.0 mmol) and stirring for 12 h
more. The reaction was cooled down to room temperature
and poured into methanol–water. The precipitates were
collected by filtration, and further purified by extracting
with methanol, acetone and n-hexane in sequence for
24 h by using a Soxhlet apparatus. The reprecipitation
from CHCl3-methanol was repeated several times. The
final product was obtained after drying in vacuum, yield
32%. GPC: Mn = 1.31×104, PDI = 1.74. The feed amount
of monomers, molecular weight and their distribution of
polymers prepared are presented in Table 1.
1
from absolute ethanol. Yield 46%. H NMR spectrum,
δ, ppm: 8.08 d (1H, benzothiazole), 7.95 d (2H, phenyl),
7.92 d (1H, benzothiazole), 7.62 d (2H, phenyl), 7.50 d
(1H, benzothiazole), 7.42 d (1H, benzothiazole). Maldi-
TOF-MS: m/z: 210.5299 [M – 80]+.
(4-BrPhBt)2Ir(4-BrPhBt)2 (4). A mixture of 2-eth-
oxyethanol with water (3 : 1 v/v) was added to a flask
that contained IrCl3·3H2O 96.8 mg (0.28 mmol) and
0.2 g(0.69 mmol) 2-(4-bromophenyl)benzo[d]thiazole
(3). The mixture was refluxed under the atmosphere of
nitrogen for 24 h. Upon cooling down, the solution was
poured into water, the red-brown precipitate was collected
and dried under vacuum.
(4-BrPhBt)2Ir(Pytz)(M1). 40.2 mg of (0.28 mmol)
2-(1H-1,2,4-triazol-5-yl)pyridine (2) were added to
the mixture of 177.6 mg (0.17mmol) chlorido-bridged
dimer 4 with 30 mg of Na2CO3 and 25 mL of 2-ethoxy-
ethanol, and then the slurry was refluxed for 12 h under
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 89 No. 12 2019

2508
LIU et al.
PL spectra of PFO exhibited emission peaks at 417 and
441 nm. PFCz emission with at 433 nm, the overlap be-
tween PLemission of the host polymer and the absorption
of iridium complex in the range of 400 to 500 nm indi-
cated an energy transfer between the host and the guest.
417
228
433
1.0
0.8
0.6
0.4
0.2
0.0
1.0
0.8
0.6
0.4
0.2
0.0
2
316
1
PL spectra of the polymers PFOIr(PhStz) in CHCl3
and in solid film are presented in Fig. 4. Photoluminescent
spectra of polymers were more or less consistent in a
solution. The bands with maxima at 417 and 439 nm
were originated from the fluorene segment, and the
emission peaks at 535 and 575 nm attributed to the
iridium complex disappeared, due to the weak energy
transfer from host to guest in solution state. However,
for the solid film, the emission peaks of PFO and iridium
complex were recorded at 419 and 443 nm and 590 and
640 nm, respectively. The PL emission of the polymer
demonstrated also red shifts ca 60 nm compared with
the emission of iridium complex (535 and 575 nm),
which was due to the extended conjugation length of the
polymer backbone in a solid film. When the content of
iridium complex was 2.5, 5.0, and 10% respectively, the
emission intensity of the guest gradually increased, the
ratios of corresponding emission and the PFO emission
peak intensities were 1.57, 1.99, and 2.43, indicating
the increased trend of the energy transfer from fluorene
segments to the iridium complex connected efficiently to
the main chain [22–24].
3
383
442
300
400
500
600
Wavelength, nm
Fig. 3. UV/Vis absorption of (1) (4-BrPhBt)2Ir(Pytz) in CHCl3
and PL emission spectra of (2) PFO, (3) PFCz in solid film.
RESULTS AND DISCUSSION
Photophysical properties. UV/Vis absorption of the
complex (4-BrPhBt)2Ir(Pytz) in CHCl3 and PL emission
spectra of PFO, PFCz in solid film are presented in Fig. 3.
For the complex, the strong absorption bands at 228 and
316 nm were derived from the π→π* transition charac-
teristic for the C^N ligands. The absorption peak around
383 nm was attributed to metal-to-ligand charge-transfer
(1MLCT) and ligand-to-ligand charge-transfer transitions
[19]. The long tail absorption in the range 400-500 nm
was assigned to the mix states containing spin-orbit cou-
pling enhanced π→π* and 3MLCT transitions [20, 21].
Comparison of the profiles of Figs. 4 and 5, dem-
onstrated that the behavior of fluorescence emission of
the backbone of PFCz was the same as PFO in CHCl3
(a)
(b)
417
535
1000
800
600
400
200
0
1.0
0.8
0.6
0.4
0.2
0.0
1.0
575
590
0.8
439
1
4
3
2
3
0.6
2
1
640
419
443
0.4
0.2
0.0
400 450 500 550 600 650 700
Wavelength, nm
350
400
450
500
550
600
Wavelength, nm
Fig. 4. PL spectra of the polymers PFOIr(PhStz) in (a) CHCl3 and (b) solid film: (1) PFOIr(PhStz) 2.5, (2) PFOIr(PhStz) 5.0,
(3) PFOIr(PhStz) 10.0, (4) (BrPhBt)2Ir(Pytz).
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 89 No. 12 2019

SYNTHESIS AND PROPERTIES OF MAIN-CHAIN PHOSPHORESCENT POLYMER
(a) (b)
2509
399
588
1.0
0.8
0.6
0.4
0.2
0.0
1000
800
600
400
200
0
421
2
446
2
635
1
1
427
449
404
350 400 450 500 550 600
Wavelength, nm
400 450 500 550 600 650
Wavelength, nm
Fig. 5. PL spectra of the polymers PFCzIr(PhStz) in (a) CHCl3 and (b) solid film: (1) PFCzIr(PhStz) 2.5 and (2) PFCzIr(PhStz) 5.0.
solution and the film solid state. Emission peak of the
polymer exhibited red shifts to 588 and 635 nm, and
the polymer also demonstrated the orange-red emission.
The energy transfer from PFCz segments to the iridium
complex bonded to the main chain was efficient. Increase
of iridium complex content in polymers resulted in the
emission intensity of host at 427 nm declining and the
emission intensity of the guest at 588 nm growing. The
ratios of maximum peak intensity between guest and host
were 1.83, 4.91, compared with the ratios of 1.57, 1.99 for
PFO system, which indicated that energy transfer from
the host to the iridium complex became more efficient
for PFCz system.
Generally, the fluorescence quantum yield (PLQY)
was an important basis for measuring the luminous
performance of a material. For the stronger photolumine-
scence intensity and the higher brightness, the quantum
yield was really important. We used FLS920-stm transient
fluorescence spectrometer to study PLQYof the polymers
in solid film (Table 2).
The results demonstrated that the PLQY of
PFOIr(PhStz) and PFCzIr(PhStz) polymers varied along
with the content of iridium complex. The PLQY of the
Table 2. Photophysical properties of the polymers
Compound
(4-BrPhBt)2Ir(Pytz)
PFOIr(PhStz) 2.5
PFOIr(PhStz) 5.0
PFOIr(PhStz) 10
PFCzIr(PhStz) 2.5
PFCzIr(PhStz) 5.0
λ
abs,solution (nm)
λPL,solution (nm)
534, 573
λPL,film (nm)
535, 575
PLQY(%)
9.38
228, 316, 383, 442
378
384
383
350
350
417, 439
418, 443, 588, 634
12.82
9.08
417, 439
420, 443, 587, 634
417, 439
423, 443, 591, 639
7.18
398, 420, 444
399, 421, 446
404, 427, 449, 586, 633
403, 424, 448, 588, 635
16.32
22.74
Table 3. Electroluminescent properties of polymers
Polymer PFOIr(PhStz) 2.5 PFOIr(PhStz) 5.0 PFOIr(PhStz) 10.0 PFCzIr(PhStz) 2.5 PFCzIr(PhStz) 5.0
Turn on,V
6
449
6
663
6
279
6
1483
6
1568
Brightnessmax, cd/m2
LEmax, cd/A
2.07
2.41
0.59
5.27
6.24
PEmax, lm/w
0.58
0.59
0.19
2.36
2.45
CIE1931 (10V)
(0.489, 0.289)
(0.501, 0.418)
(0.528, 0.397)
(0.557, 0.412)
(0.576, 0.410)
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 89 No. 12 2019

2510
LIU et al.
(a)
(b)
200
2400
2000
1600
1200
800
400
0
200
160
120
80
1000
800
600
400
200
0
160
120
80
40
40
0
0
–40
–40
0
4
8
12 16 20
0
3
6
9
12 15 18
Voltage, V
Voltage, V
Fig. 6. The current density-voltage-brightness curves of the (a) PFOIr(PhStz) 5.0 and (b) PFCzIr(PhStz) 5.0 OLED devices.
polymer system PFCzIr(PhStz) 2.5 and PFCzIr(PhStz)
5.0 increased to 16.31 and 22.74%, respectively, com-
pared with 9.38% of the PLQY of the iridium complex.
However, with the increase of iridium complex content,
the PLQY of PFOIr(PhStz) polymers first increased and
then decreased, which could be due to the energy transfer
between the host and the guest, so that the decline trend of
the yield reflected by the polyfluorene subject was higher
than the increase trend of the energy reflected by the irid-
ium complex guest. The above results demonstrated that
the photoluminescence performance of PFCzIr(PhStz)
system was better than that of PFOIr(PhStz) system.
Electroluminescent properties. The current density-
voltage-brightness curves of the PFOIr(PhStz) 5.0 and
PFCzIr(PhStz) 5.0 OLED devices are presented in Fig. 6,
and the electroluminescent properties of polymers are
shown in Table 3. In the system of PFOIr(PhStz), the turn-
on voltage of the polymer electroluminescent devices was
at 6 V. Generally, the overall luminescence performance
of the devices was not ideal. On one hand, it could be
related to the luminescence color of the polymer, on the
other hand, it could be caused by the complex manufac-
turing process and the parameters of the devices. For the
PFCzIr(PhStz) system, the turn-on voltage was the same
at 6 V, but at 10 V the color was more full. When the
iridium complex content was 5%, the brightness of the
device was 1568 cd/m2, the luminous efficiency reached
6.24 cd/A, and the power efficiency reached 2.45 lm/w.
When the current density was in the range of 60–
380 mA/cm2, the power efficiency and luminous effi-
ciency rolled off slowly (Fig. 7). The overall brightness
and efficiency of the devices were significantly improved
compared to the PFOIr(PhStz) system.
Electrochemical properties. The HOMO and LUMO
levels of the PFCzIr(PhStz) system were determined to be
slightly higher than those of PFOIr(PhStz). The HOMO
energy level was 5.36–5.71 eV, and the LUMO energy
level was 2.48–2.85 eV.
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
CONCLUSIONS
The main-chain phosphorescent polymers
PFCzIr(PhStz) and PFOIr(PhStz) with iridium complex
have been synthesized by the Suzuki polycondensation,
in which the fluorene-carbazole(PFCz) or fluorine(PFO)
segment have been used as a polymer backbone. Pho-
toluminescence and electroluminescence confirm that
these two polymers have efficient energy transfer from
the main chain to the iridium complex. The devices
performance demonstrates orange-red emission. Com-
paring with the backbone of PFO, the photoluminescent
0
60 120 180 240 300 360
Current density, mA/cm
2
Fig. 7. The luminous efficiency-current density-power
efficiency curves of the PFCzIr(PhStz) 5.0 OLED device.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 89 No. 12 2019

SYNTHESIS AND PROPERTIES OF MAIN-CHAIN PHOSPHORESCENT POLYMER
2511
Metals, 2009, vol. 159, p. 1876.
https://doi.org/10.1016/j.synthmet.2009.06.013
and electroluminescent properties of PFCz polymer
system are better, and the energy transfer between host
and guest is more efficient. Fluorescence quantum ef-
ficiency of PFCzIr(PhStz) 5.0 reaches 22.74%, the best
device performances are achieved with PFCzIr(PhStz) 5.0
characterized by a maximum brightness of 1568 cd/m2 at
14 V, and the luminous efficiency reaches 6.24 cd/A, and
power efficiency is as high as 2.45 lm/w.
10. Li, T.-Y., Wu, J., Wu, Z.-G., Zheng, Y.-X., Zuo, J.-L., and
Pan, Y., Coord. Chem. Rev., 2018, vol. 374, p. 55.
https://doi.org/10.1016/j.ccr.2018.06.014
11. Chi, Y. and Chou, P.-T., Chem. Soc. Rev., 2010,
vol. 39, p. 638.
https://doi.org/10.1039/b916237b
12. Ho, C.-L. and Wong, W.-Y., Chem. Rev., 2013,
vol. 257, p. 1614.
FUNDING
https://doi.org/10.1016/j.ccr.2012.08.023
13. Liu, B., Dang, F., Tian, Z., Feng, Z., Jin, D., Dang, W.,
Yang, X., Zhou, G., and Wu, Z., ACS Appl. Mater.
Inter., 2017, vol. 9, no. 19, p. 16360.
This work was supported by the National Natural Science
Foundation of China (21374017 and 21574021), Natural Sci-
ence Foundation of Fujian Province (2017J01683), Program
for Innovative Research Team in Science and Technology in
Fujian Province University (IRTSTFJ).
https://doi.org/10.1021/acsami.7b04509
14. Mao, H.-T., Zang, C.-X., Shan, G.-G., Sun, H.-Z.,
Xie, W.-F., and Su, Z.-M., Inorg. Chem., 2017, vol. 56,
no. 16, p. 9979.
https://doi.org/10.1021/acs.inorgchem.7b01516
15. Mydlak, M., Yang, C.-H., Polo, F., Galstyan, A., Dani-
liuc, C.G., Felicetti, M., Leonhardt, J., Strassert, C.A., and
De Cola, L., Chem. – Eur. J., 2015, vol. 21, no. 13,
p. 5161.
CONFLICT OF INTEREST
No conflict of interest was declared by the authors.
AUTHOR CONTRIBUTION
Chao Liu and Dongdong Li contributed equally to this
work.
https://doi.org/10.1002/chem.201405839
16. Zhao, J.-H., Hu, Y.-X., Lu, H.-Y., Lü, Y.-L., and
Li, X., Org. Electr., 2017, vol. 41, p. 56.
https://doi.org/10.1016/j.orgel.2016.11.039
17. Wei, X., Peng, J., Cheng, J., Xie, M., Lu, Z., Li, C., and
Cao, Y., Adv. Func. Mater., 2007, vol. 17, no. 16, p. 3319.
https://doi.org/10.1002/adfm.200700359
REFERENCES
1. Wang, Y., Bai, K., Wang, S., Ding, J., and Wang, L., ACS
Appl. Mater. Interfaces, 2018, vol. 10, no. 38, p. 32365.
https://doi.org/10.1021/acsami.8b06750
2. Yang, X., Zhou, G., and Wong, W.-Y., Chem. Soc.
Rev., 2015, vol. 44, p. 8484.
https://doi.org/10.1039/c5cs00424a
3. Ying, L., Ho, C.-L., Wu, H.-B., Cao, Y., and Wong,
W.-Y., Adv. Mater., 2014, vol. 26, p. 2459.
18. Ranger, M., Rondeau, D., and Leclerc, M., Macromol.,
1997, vol. 30, no. 25 p. 7686.
https://doi.org/10.1021/ma970920a
19. Han, L., Yang, D., Li, W., Chu, B., Chen, Y., Su, Z.,
Zhang,D., Yan, F., Wu, S., Wang, J., Hu, Z., and Zhang, Z.,
Appl. Phys. Lett, 2009, vol. 94, p. 163303.
https://doi.org/10.1002/adma.201304784
4. Miao, Y.-Q., Gao, Z.-X., Wang, H., Jia, H.-S., Liu, X.-G.,
Xu, B.S., and Wei, B., Org. Electron, 2015,
vol. 23, p. 199.
https://doi.org/10.1063/1.3122938
20. Langecker, J., Karg, O., Meusinger, R., and Rehahn, M.,
J. Organomet. Chem., 2018, vol. 862, p. 105.
https://doi.org/10.1016/j.jorganchem.2018.02.032
21. Lai, W.-Y., Levell, J.W., Jackson, A.C., Lo, S.-C., Bern-
hardt, P.V., Samuel, I.D.W., and Burn, P.L., Macromol.,
2010, vol. 43, no. 17, p. 6986.
https://doi.org/10.1016/j.orgel.2015.05.006
5. Kumar, S., Surati, K.R., Lawrence, R., Vamja, A.C.,
Yakunin, S., Kovalenko, M. V., and Shih, C.-J., Inorg.
Chem., 2017, vol. 56 , p. 15304.
https://doi.org/10.1021/acs.inorgchem.7b02872
6. Page, Z.A., Narupai, B., Pester, C.W., Bou Zer-
dan, R., Sokolov, A., Laitar, D.S., and Hawker, C.J.,
ACS Central Sci., 2017, vol. 3, p. 654.
https://doi.org/10.1021/ma101363h
22. Yu, T., Xu, Z., Su, W., Zhao, Y., Zhang, H., and Bao, Y.,
Dalton Trans., 2016, vol. 45, no. 34, p. 13491.
https://doi.org/10.1039/c6dt02383e
23. Kuo, H.-H., Chen, Y.-T., Devereux, L.R., Wu, C.-C.,
Fox, M.A., Kuei, C.-Y., Chi, Y., and Lee, G.-H., Adv.
Mater., 2017, vol. 29, no. 33, p. 1702464.
https://doi.org/10.1021/acscentsci.7b00165
7. Zhong, Z., Wang, X., Ma, Y., Peng, F., Guo, T.,
Jiang, J.-X., Ying, L., Wang, J., Peng, J., and Cao, Y.,
Org. Electr., 2018, vol. 57, p. 178.
https://doi.org//10.1016/j.orgel.2018.03.008
8. Guo, T., Yu, L., Zhao, B., Li, Y., Tao, Y., Yang, W.,
Hou Q., Wu, H., and Cao, Y., Macromol. Chem.
Phys., 2012, vol. 213, p. 820.
https://doi.org/10.1002/adma.201702464
24. Hu, Y.-X., Xia, X., He, W.-Z., Tang, Z.-J., Lv, Y.-L., Li, X.,
and Zhang, D.-Y., Org. Electr., 2019, vol. 66, p. 126.
https://doi.org/10.1016/j.orgel.2018.12.029
https://doi.org/10.1002/ macp. 201100676
9. Liang, B., Xu, Y., Chen, Z., Peng, J., and Cao, Y., Synth.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 89 No. 12 2019