Highly efficient orange-red electroluminescence of iridium complexes with good electron mobility

Article abstract of DOI:10.1039/c7tc02117h

Two iridium complexes with 1-(2,6-bis(trifluoromethyl)pyridin-4-yl)isoquinoline (tfmpiq) and 4-(2,6-bis(trifluoromethyl)pyridin-4-yl)quinazoline (tfmpqz) main ligands and a tetraphenylimidodiphosphinate (tpip) ancillary ligand were applied in organic light-emitting diodes (OLEDs). The introduction of quinazoline greatly influences the nature of the complex. The quantum yield and the electron mobility of Ir(tfmpqz)₂(tpip) are much higher than those of Ir(tfmpiq)₂(tpip) (Ir(tfmpiq)₂(tpip): Φ: 0.47, μ_e: 8.93-9.47 × 10^-6 cm² V^-1 s^-1 under an electric field from 1040 (V cm^-1)^1/2 to 1300 (V cm^-1)^1/2; Ir(tfmpqz)₂(tpip): Φ: 0.98, μ_e: 6.44-7.20 × 10^-6 cm² V^-1 s^-1 under an electric field from 1040 (V cm^-1)^1/2 to 1300 (V cm^-1)^1/2). In addition, the Ir(tfmpqz)₂(tpip)-based device also displayed better performance than that using Ir(tfmpiq)₂(tpip). Furthermore, with a europium complex, Eu(DBM)₃phen (DBM = dibenzoylmethide; phen = 1,10-phenanthroline) as a sensitizer, the device based on Ir(tfmpqz)₂(tpip) with a double emissive layer structure of ITO/MoO₃ (3 nm)/TAPC (50 nm)/Ir(tfmpqz)₂(tpip) (5 wt%):TcTa (10 nm)/Eu(DBM)₃phen (0.2 wt%):Ir(tfmpqz)₂(tpip) (5 wt%):26DCzPPy (10 nm)/TmPyPB (50 nm)/LiF (1 nm)/Al (100 nm) displayed the best performance with a maximum luminance of 129466 cd m^-2, and a maximum current efficiency and a maximum power efficiency of 62.96 cd A^-1 and 53.43 lm W^-1, respectively, with low efficiency roll-off. The current efficiency still remains as high as 58.84 cd A^-1 at a brightness of 1000 cd m^-2 and 53.27 cd A^-1 at a brightness of 5000 cd m^-2. These results suggest that Ir(iii) complexes with quinazoline units are potential orange-red phosphorescent materials for OLEDs.

Full text of DOI:10.1039/c7tc02117h

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Cite this: DOI:
Highly efficient orange-red electroluminescence of
iridium complexes with good electron mobility
10.1039/x0xx00000x
1,#
2, #
1
1
HuaꢀBo Han , RongꢀZhen Cui , YiꢀMing Jing , GuangꢀZhao Lu , YouꢀXuan
*,1
*,2
1
2
Zheng , Liang Zhou , JingꢀLin Zuo , Hongjie Zhang
Two iridium complexes with 1ꢀ(2,6ꢀbis(trifluoromethyl)pyridinꢀ4ꢀyl)isoquinoline (tfmpiq)
and 4ꢀ(2,6ꢀbis(trifluoromethyl)pyridinꢀ4ꢀyl)quinazoline (tfmpqz) main ligands and
tetraphenylimidodiphosphinate (tpip) ancilary ligand were applied in organic lightꢀemitting
diodes (OLEDs). The introducing of quinazoline has greatly influence on the nature of the
Received 00th January 2017,
Accepted 00th January 2017
complex. The quantum yield and the electron mobility of Ir(tfmpqz) (tpip) are much higher
2
ꢀ
6
2
ꢀ1 ꢀ1
than that of Ir(tfmpiq) (tpip) (Ir(tfmpiq) (tpip): Φ: 0.47,
ꢀ
e: 8.93ꢀ9.47 × 10 cm V s
2
2
DOI: 10.1039/x0xx00000x
ꢀ1 1/2
ꢀ1 1/2
under the electric field from 1040 (V cm ) to 1300 (V cm ) ; Ir(tfmpqz) (tpip): Φ: 0.98,
2
ꢀ6
2
ꢀ1 ꢀ1
ꢀ1 1/2
www.rsc.org/MaterialsC
ꢀ : 6.44ꢀ7.20 × 10 cm V s under the electric field from 1040 (V cm ) to 1300 (V
e
ꢀ
1 1/2
cm ) ). Besides, the Ir(tfmpqz) (tpip) based device also displayed better performances
2
than that using Ir(tfmpiq) (tpip). Furthermore, with an europium complex Eu(DBM) phen
2
3
(
DBM = dibenzoylmethide; phen = 1,10ꢀphenanthroline) as a sensitizer, the device based on
Ir(tfmpqz) (tpip) with a double emissive layers structure of ITO / MoO (3 nm) / TAPC (50
2
3
nm) / Ir(tfmpqz) (tpip) (5 wt%): TcTa (10 nm) / Eu(DBM) phen (0.2 wt%): Ir(tfmpqz) (tpip)
2
3
2
(
5 wt%): 26DCzPPy (10 nm) / TmPyPB (50 nm) / LiF (1 nm) / Al (100 nm) displayed best
ꢀ
2
performances with a maximum luminance of 129 466 cd m , a maximum current efficiency
and a maximum power efficiency of 62.96 cd A and 53.43 lm W , respectively, with low
efficiency rollꢀoff. The current efficiency still remains as high as 58.84 cd A at the
brightness of 1 000 cd m and 53.27 cd A at the brightness of 5 000 cd m , respectively.
These results suggest that the Ir(III) complexes with quinazoline units are potential
orangeꢀred phosphorescent materials for OLEDs.
ꢀ
1
ꢀ1
ꢀ1
ꢀ
2
ꢀ1
ꢀ2
guest molecule should be used as a deep trap for the electron and
hole in an emitting layer, leading to an enhancement of the
driving voltage. In addition, for red dopants, the selfꢀquenching
Introduction
The phosphorescent iridium(III) complexes have been
extensively studied in organic lightꢀemitting diodes (OLEDs)
because of their high quantum efficiency and the wide range of
and tripletꢀtriplet annihilation are too serious to be ignored
especially when the doping concentrations are high. Thus, from
perspective of reality, solving the above issues via the design of
1
5
emission colors. The strong spinꢀorbit coupling (SOC) can
materials or/and the optimization of device is inevitable.
promote triplet to ground radiative transition by introducing the
central heavy atom, which leads to a quite high phosphorescence
Since tris(1ꢀphenylisoquinline)iridium(III) Ir(piq)3 and
bis(1ꢀphenylꢀisoquinoline)(acetylacetonato)iridium(III)
quantum
efficiency
in
unusual.
Furthermore,
the
Ir(piq) (acac) have been synthesized as red PHOLEDs materials
by Y.ꢀJ. Su et al. the first time, many efficient red emitters and
2
6
phosphorescence of Ir(III) complexes generates by the
metalꢀtoꢀligand charge transfers (MLCT) and ligandꢀcentered
devices have been developed based on isoquinoline derivatives
due to their high electron affinities. R.ꢀH. Liu and K.ꢀT. Wong
2
7
(
LC) transition, so that it is possible to control the excited state’s
energy level by adjusting ligands via the substituent effect.
Quite high efficiency has been obtained for green
phosphorescent devices, while the highest efficiency that has
been reported for red emitters based devices is still much lower.
Red emission is a crucial monochromatic light and also a pivotal
used bulky and halogen substituent to reduce the impact of
selfꢀquenching. Wong et al. reported a range of red emitters
combining 9ꢀarylcarbazole and triphenylamine in complex
8
9
Ir(piq) (acac). Wong and Chen groups have suppressed close
2
1
0
packing among the molecules by increasing steric hindrance.
In addition, great efforts have been made based on
ꢀphenylquinoline (phq), 2,4ꢀdiphenylquinoline, pyridine
3
constituent for the development of fullꢀcolor display. While the
design of efficient redꢀemitting materials is much harder
compared to other colors, which is consistent with the law of
2
11
derivatives and so on.
4
energy gap. Most of red emitters are subjected to the heavy
It is wellꢀknown that the balance of the electronꢀhole injection
and transport is necessary for highꢀefficiency OLEDs using the
Ir(III) complexes because both the charge carrier balance
deterioration and nonradioactive quenching processes increase
will cause a serious efficiency rollꢀoff. Since the majority of
holeꢀtransporting materials’ hole mobility is much higher than
the electronꢀtransporting materials’ electron mobility, the OLEDs
concession on the color purity and device efficiency. Because the
characteristic emission is in the spectral zone where eyes are
insensitive, luminosity of red devices is lower. Moreover, the
difference between the host with wide bandgap and the
redꢀemitting guest with narrow bandgap is quite enormous in the
level of the highest occupied molecular orbital (HOMO) and/or
lowest unoccupied molecular orbital (LUMO). Therefore, the
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DOI: 10.1039/C7TC02117H
performances depend on electron transport’s capability.
Therefore, the use of ambipolar host materials is essential to gain
phosphorescent OLEDs with low efficiency rollꢀoff, as well as
chloroꢀbridged dimer. Purification of the mixture by silica gel
chromatography provided crude products, which were further
purified by vacuum sublimation. All the new compounds were
1
2
1
the synthesis of dopants with excellent electron mobility.
From our previous work, we found
fully characterized by H NMR, the electrospray ionization mass
that
spectra (ESIꢀMS) and elemental analyses.
Cl
N
tetraphenylimidodiphosphinate (tpip) is a good ancillary ligand
for Ir(III) complexes due to their four bulky aromatic groups,
leading to an increase of the spatial separation from neighboring
molecules to suppress TTA (tripletꢀtriplet annihilation), TPA
F
3
3
C
N
C
tfmpiq
tfmpqz
F
3
C
N
CF
3
F
3
C
N
CF
3
N
1
)LDA
F
2
)B(OPr-i)
3
B(OH)
2
F
3
C
N
N
Cl
1
3
N
C
N
(
tripletꢀpolaron annihilation) effectively, as well as the ability of
Ph P=O to improve the ability of electron injection and
transportation. Moreover, the bulky CF
N
F
3
2
1
4
F
3
C
N
CF
3
3
substituents can affect
O
P
F
3
C
N
CF
3
F
3
C
N
CF
3
N
Ir
the molecular packing and the steric protection surrounding the
metal would restrain the selfꢀquenching impact，and the CꢀF
bond with low vibrational frequency can reduce radiationless
Cl
Cl
O P
OP
N
Ir
2
Ir
NK
2
HOP
N
N
2
IrCl
3
2
Ir(tfmpiq) (tpip)
F
3
C
N
N
CF
3
F
3
C
N
N
CF
3
15
F3C
N
CF3
deactivation rate. Besides that, nitrogen heterocycle would also
enhance the electron affinity and the electron mobility of the
Ir(III) complexes.
Cl
Cl
O
P
Ir
Ir
N
Ir
N
2
N
O P
2
N
2
N
Therefore, aiming to get efficient devices by improving the
electron mobility, both 2,6ꢀbisꢀtrifluoromethylꢀpyridine and
quinazoline were introduced to replace the widely used phenyl
Ir(tfmpqz)2(tpip)
Scheme 1. Synthetic routes of ligands and the complexes.
Furthermore, The structures of Ir(tfmpiq)
and piq units. The complexes Ir(tfmpiq)
2
(tpip) (tfmpiq =
ꢀ(2,6ꢀbis(trifluoromethyl)pyridinꢀ4ꢀyl)isoquinoline) and
(tpip) (tfmpqz = 4ꢀ(2,6ꢀbis(trifluoromethyl)pyridinꢀ
2
(tpip) and
1
2
Ir(tfmpqz) (tpip) complexes were proved via the single crystals
Ir(tfmpqz)
2
and their crystal diagrams are displayded in Fig. 1. The
molecular parameters and atomic coordinates were showed in the
Table S1, Table S2 (Supporting Information), respectively. From
the structures diagram of crystals it can be found that the iridium
atom is embraced by C, N and O atoms from tfmpiq/tfmpqz or
tpip, with a twisted octahedral coordination geometry. For
4
ꢀyl)quinazoline) displayed emissions peak at 591 and 588 nm,
respectively. Besides, the devices with both complexes showed
good performances, and the device based on Ir(tfmpqz) (tpip)
displayed better performances than the device based on
Ir(tfmpiq) (tpip) due to the higher photoluminescence (PL)
2
2
efficiency and better electron mobility.
Ir(tfmpiq)
2 2
(tpip) and Ir(tfmpqz) (tpip), angles of [OꢀIrꢀO] are
Furthermore, aiming to enhance the EL performances based on
8
8
2
2
9.94(13)° ꢀ 90.64(12)°, and the angle of [CꢀIrꢀN] is 80.06(14)° ꢀ
Ir(tfmpqz)
Eu(DBM)
,10ꢀphenanthroline) with lowꢀlying highest occupied molecular
orbital (HOMO) and/or lowest unoccupied molecular orbital
LUMO) levels to sensitize the Ir(III) complex in an electron
2
(tpip), we employed an europium(III) complex
0.72(18)°. The lengths of IrꢀC bonds range from 1.992(4) ꢀ
.010(4) Å. The IrꢀN bonds have the lengths of 2.024(4) ꢀ
.038(3) Å. And the lengths of IrꢀO bonds are longer a bits,
3
phen (DBM dibenzoylmethide; phen
=
=
1
which are 2.157(3) ꢀ 2.167(3) Å. These results are similar to the
parameters of the cyclometalated Ir(III) complexes that have
been reported.
(
dominant lightꢀemitting layer (EML). Consequently, the device
displayed the best performances with a maximum current
ꢀ
1
efficiency (ηc,max) of 62.96 cd A with low efficiency rollꢀoff.
Because of the low doped concentration (0.2 wt%) of the Eu(III)
complex, the cost of this type device for practical application is
not increase greatly from the industrial and economical point of
view.
Results and discussion
Preparation and X-ray crystallography
Scheme 1 shows the chemical structures and synthetic routes of
ligands
and
Ir(III)
complexes.
with
The
reaction
of
Fig. 1. The crystal diagrams of Ir(tfmpiq)
2
(tpip) (CCDC No.1536092)
2
,6ꢀbis(trifluoromethyl)ꢀpyridine
LDA
(lithium
and Ir(tfmpqz) (tpip) (CCDC No.1536093) shown at 30% probability
2
diisopropylamide) and B(OPrꢀi)3 gave two crude aryl boronic
acids. The corresponding two trifluoromethyl fluorinated
bipyridine ligands (tfmpiq and tfmpqz) were synthesized using
a Suzuki coupling reaction. The tetraphenylimidodiphosphinate
acid (Htpip) and potassium salt (Ktpip) were prepared according
to our previous publications. The iridium complexes were
obtained in two steps with popular methods via Ir(III)
level. The hydrogen atoms are omitted for clarity.
Thermal stability
The thermal stability of the materials is crucial for efficient
OLEDs. If a complex can be applied in practical OLEDs, the
melting point (T ) and decomposition temperature (T ) need to
m d
2
2
| J. Mater. Chem. C, 2017, 00, 1-9
017
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DOI: 10.1039/C7TC02117H
be high enough to guarantee that the complex could be deposited
onto the solid face without any decomposition on sublimation.
The scanning calorimetry (DSC) and thermogravimetric analysis
level is beneficial to trap the electron and broaden the
recombination zone, leading to the improvement of the EL
performances partly.
(
TGA) curves of Ir(tfmpiq)
showed in Fig. S1. From the DSC crves it is can be seen that the
melting points of Ir(tfmpiq) (tpip) and Ir(tfmpqz) (tpip) are
31 C and 343 C, respectively. It is can be figured out that there
2 2
(tpip) and Ir(tfmpqz) (tpip) are
Photophysical property
2
2
The UVꢀvis absorption and photoluminescence spectra of the two
o
o
3
complexes Ir(tfmpiq)
2
(tpip) and Ir(tfmpqz)
2 2 2
(tpip) in CH Cl
o
is no loss was observed below 340 C in weight from the curves
of TGA, and the decomposition temperature (5% loss of weight)
is 357 C for Ir(tfmpiq)
respectively, suggesting that both complexes have the potential
for use in OLEDs. In general, the efficiency of vacuumꢀdeposited
OLEDs is much higher than that of solutionꢀprocessed devices.
ꢀ5
(5×10 M) are shown in Fig. 2. The broad and intensive
absorption bands below 320 nm are due to the spinꢀallowed
o
2
(tpip) and 354 °C for Ir(tfmpqz)
2
(tpip),
1
intraligand LC (πꢀπ*) transition of tfmpiq/tfmpqz and tpip
ligands. The weak absorption lasting to 520 nm should be
attributed to the metalꢀligand charge transfer band (MLCT),
and/or broad LC absorptions. The strongest emissions peak at
5
91 and 588 nm in CH
between the lowest triplet excited state and the ground state,
which makes Ir(tfmpiq) (tpip) and Ir(tfmpqz) (tpip)
2 2
Cl , produced by the electronic transition
Electrochemical properties and theoretical calculation
The frontier molecular orbitals (FMOs), especially the HOMO
and LUMO, are pretty crucial to the design of device structure.
Therefore, aiming to measure energy levels of the
HOMO/LUMO, the electrochemistry measurements by cyclic
voltammetry (CV) were adopted with ferrocene as the internal
2
2
orangeꢀred phosphors. The emissions in the scope of lower
energy around 637 nm may generate by the overlapping
1
8
vibrational satellites. Furthermore, the complexes show much
high quantum efficiency as 0.47 and 0.98 for Ir(tfmpiq) (tpip)
and Ir(tfmpqz) (tpip), respectively. The differences of the
absorption and emission profiles between Ir(tfmpiq) (tpip) and
Ir(tfmpqz) (tpip) suggest that the introduction of quinazoline
does have an obvious effect, and it can increase the quantum
efficiency greatly. Furthermore, the phosphorescence lifetime (τ)
is the crucial factor that determines the rate of tripletꢀtriplet
annihilation in OLEDs. Longer τ values usually cause greater
tripletꢀtriplet annihilation. The lifetimes of the the complexes are
2
standard in CH
3
CN (Fig. S2). The HOMO level was obtained via
2
the oxidation potential and then the LUMO level was calculated
by the HOMO and the band gap observed from UVꢀvis
absorption spectra. During the progress of anodic oxidation, an
obvious oxide peak can be observed for all complexes with the
oxidation potential in 1.31ꢀ1.51 V, which can be ascribed to the
metalꢀcentered Ir(III)/Ir(IV) oxide couple, consistent with the
2
2
1
6
2
cyclometallated Ir(III) system reported. Ir(tfmpiq) (tpip)
exhibits a lower oxidation potential (1.31 V) and HOMO/LUMO
energy levels are ꢀ5.94/ꢀ3.87 eV. The oxidation potential of
Ir(tfmpiq) (tpip) increases to 1.51 V and the HOMO/LUMO
2
2 2
in the range of microseconds (2.70 and 2.44 ꢁs in CH Cl
solution respectively) at room temperature (Fig. S3 and Table 1)
and are indicative of the phosphorescent origin for the excited
states in each case.
energy levels are ꢀ6.25/ꢀ4.14 eV.
Furthermore, it can be observed from the theoretical
calculation that nearly all LUMOs are on tfmpiq/tfmpqz ligands
(a)
8000
(b)
Ir(tfmpiq)
Ir(tfmpqz)
2
(tpip)
(tpip)
Ir(tfmiq)
2
(tpip)
2
(tpip)
Ir(tfmqz)
2
(
(
94.73ꢀ95.11%) and rarely situated on iridium atom
2.98ꢀ3.378%) and tpip ancillary ligand (1.52ꢀ2.28%). While
6
4
000
000
HOMOs are situated on tfmpiq ligands (46.07%), d orbitals on
iridium atom (48.14%) and tpip ancillary ligand (5.79%) for
2000
0
2 2
Ir(tfmpiq) (tpip). For Ir(tfmpqz) (tpip), HOMOs are situated
2
40
300
360
420
480
540
600
550
600
650
700
on tfmpqz ligands (36.88%) and d orbitals of iridium atom
Wavelength (nm)
Wavelength (nm)
1
7
(
53.77%) and tpip ancillary ligand (9.35%). The introducing of
Fig. 2. (a) UVꢀvis absorption and (b) emission spectra of
Ir(tfmpiq) (tpip) and Ir(tfmpqz) (tpip) complexes in degassed CH Cl
solutions (5.0 × 10 mol L ) at room temperature.
quinazoline does influence the electron distributions of the
complexes, resulting the decrease of the HOMO and LUMO
2
2
2
2
ꢀ5
ꢀ1
level, which lead to the nature differences of Ir(tfmpiq)
2
(tpip)
and Ir(tfmpqz) (tpip). What’s more, the decrease of the LUMO
2
Table 1. Physical properties of Ir(tfmpiq)
2 2
(tpip) and Ir(tfmpqz) (tpip).
a)
b)
c)
d)
e)
f)
Complex
Ir(tfmpiq) (tpip)
Ir(tfmpqz) (tpip)
T
m
/T
d
(°C)
λ
abs (nm)
λ
em (nm)
Φ
τ
(
ꢀ
s)
HOMO/LUMO (eV)
2
331/357
343/354
358/377/451
591
588
0.47
0.98
2.70
2.44
ꢀ5.94/ꢀ3.87
2
319/403/468
ꢀ6.25/ꢀ4.14
a)
b), c), e)
ꢀ5
ꢀ1
T
m
: melting temperature, T
d
: decomposition temperature;
Measured in degassed CH
Cl
2 2
solution at a concentration of 5 × 10 mol·L at room
(Φ = 0.4);
d)
ꢀ5
ꢀ1
temperature; Measured in degassed CH
f)
2 2
Cl
solution at a concentration of 5 × 10 mol·L at room temperature emission relative to Ir(ppy)
3
From the onset of oxidation potentials of the cyclovoltammetry (CV) diagram using ferrocene as the internal standard and the optical band gap from
CN).
the absorption spectra in degassed solution (CH
3
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DOI: 10.1039/C7TC02117H
2
ꢀ1 ꢀ1) 22
Electron mobility
4.74ꢀ4.86 ×10ꢀ6 cm V
s
.
Furthermore, the electron mobility
2
(acac) was also measured under the
of the classic red emit Ir(piq)
same conditions and the values are 5.62ꢀ5.92 × 10 cm V
According to our previous studies, an excellent electron mobility
of emitters could benefit electron transport and improve the
ꢀ6
2
ꢀ1 ꢀ1
s
ꢀ
1 1/2
ꢀ1 1/2
2
0
under the electric field from 1040 (V cm ) to 1300 (V cm )
lower than that of Ir(tfmpiq) (tpip) and Ir(tfmpqz) (tpip) (Fig.
S4.). Additionally, the electron mobility of Ir(tfmpqz) (tpip) is
better than that of Ir(tfmpiq) (tpip) suggesting that quinzoline
has the strong impact on the enhancement of the electron flow.
The result is exactly fitting our design intent to improve the
electron transport ability of the emitter. The good electron
transport ability of Ir(tfmpiq) (tpip) and Ir(tfmpqz) (tpip) will
2 2
reinforce the recombination chance of electrons and holes, so
that their devices may have good performances, especially for
,
device efficiency. To determine the two complexes’ electron
mobility, the transient electroluminescence (TEL) measurement
was carried out via the devices with a structure of ITO
2
2
2
2
(
indiumꢀtinꢀoxide)
/ TAPC (1,1ꢀbis[4ꢀ[N,Nꢀdi(pꢀtolyl)amino]
phenyl]cyclohexane, 50 nm) / Ir complexes (60 nm)/ Li (1 nm) /
2
1
Al (100 nm). The Ir complexes act as not only the emissive
layer (EML) but also electronꢀtransport layer. The experimental
results (Fig. 3) indicated that the electron mobility values of
ꢀ6
2 2
Ir(tfmpiq) (tpip) and Ir(tfmpqz) (tpip) are 6.44ꢀ7.20 × 10
2
ꢀ1 ꢀ1
ꢀ6
2
ꢀ1 ꢀ1
cm V
s and 8.93ꢀ9.47 × 10 cm V s , respectively, under
ꢀ
1 1/2
ꢀ1 1/2
2
that using Ir(tfmpqz) (tpip).
the electric field from 1040 (V cm ) to 1300 (V cm )
,
3
higher than that of Alq (aluminum 8ꢀhydroxyquinolinate,
7
(a)
V
t /ꢀs
d
(b)
V
t /
ꢀ
s
10
d
1
0
0.50
.5 0.54
9.0 0.58
.5 0.62
8.0 0.66
.5 0.72
7.0 0.78
.5 0.86
6
5
4
3
2
1
0
10 0.38
.5 0.38
0.6
0.4
0.2
9
9
8
6
4
2
0
9.0 0.42
8.5 0.46
8.0 0.48
7.5 0.54
7.0 0.54
6.5 0.62
8
7
6
(c)
Ir(tfmpiq) (tpip)
2
Ir(tfmpqz)
Alq3
(tpip)
2
1150
1200
1250
1/2
1300
0
2
4
6
8
10
0.0
-
1
0
2
4
6
8
10
Electric Field (V cm )
Time (ꢀs)
Time (ꢀs)
Fig. 3. (a), (b) the transient EL signals for the device structure of ITO/TAPC (50nm)/Ir complexes (60nm) under different applied fields of
Ir(tfmpiq) (tpip) and Ir(tfmpqz) (tpip); (c) electric field dependence of charge electron mobility in the thin films of Ir(tfmpiq) (tpip) and
Ir(tfmpqz) (tpip) and Alq
2
2
2
2
3
.
MoO
x wt%): TcTa (4,4’,4’’ꢀtris(carbazoleꢀ9ꢀyl)triphenylamine, 10
nm) / TmPyPB (1,3,5ꢀtri(mꢀpyridꢀ3ꢀylꢀphenyl)benzene, 50 nm) /
LiF (1 nm) / Al (100 nm) (Fig. 4). MoO and LiF served as holeꢀ
and electronꢀinjecting interface modified materials, respectively.
3
(molybdenum oxide, 3 nm) / TAPC (50 nm) / Ir complex
OLEDs performance
(
3
ꢀ2
2
ꢀ1 ꢀ1
TAPC owning high hole mobility (1 × 10 cm
V
s ) and
highꢀlying LUMO level (ꢀ2.0 eV) was used as hole
transport/electron block layer (HTL/EBL), while TmPyPB with
ꢀ
3
2
ꢀ1 ꢀ1
high electron mobility (1 × 10 cm
V
s ) and lowꢀlying
HOMO level (ꢀ6.7 eV) was used as electron transport/hole block
layer (ETL/HBL). Ambipolar material 26DCzPPy was chosen as
the host because its' nearly equal electron mobility (ꢀ
e
) and hole
ꢀ5
2
ꢀ1 ꢀ1
mobility (ꢀ
h
) values (1ꢀ8 × 10 cm V
s
at an electric field
5
6
ꢀ1
between 6.0 × 10 and 1.0 × 10 V cm ), which benefits the
2
3ꢀ25
electronꢀhole balance in the EML.
performances are achieved at doping level of 6% and 5% for
Ir(tfmpiq) (tpip) and Ir(tfmpqz) (tpip), respectively.
The EL spectra, luminanceꢀvoltageꢀcurrent density (LꢁVꢁJ)
curves, current efficiencyꢀluminance (ŋ ꢀL) curves, power
efficiencyꢀluminance (ŋ ꢀL) curves for G1 and G2 are shown in
The optimal device
2
2
c
p
Fig. S5, and the crucial EL data are shown in Table 2. The peaks
of EL emission are 589 and 579 nm for G1 and G2, respectively,
and the emission spectra are almost invariant of the current
density (Fig. S6(a) and Fig. S6(b)) and there is no dependence on
concentration. From the Fig.5(a), it is can be seen that the EL
spectra are almost identical to the PL spectra of the complexes,
suggesting that the devices’ EL emissions come from the triplet
excited states of the phosphors. Apart from the characteristic
Fig. 4. Energy level diagram of HOMO and LUMO levels of materials
used in this work and their molecular structures.
To confirm our assumption, we researched the single emitting
layer (EML) devices G1 and G2 using Ir(tfmpiq)
2
(tpip) and
Ir(tfmpqz) (tpip) emitters, respectively, with a structure of ITO /
2
4
2
| J. Mater. Chem. C, 2017, 00, 1-9
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Journal of Materials Chemistry C
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DOI: 10.1039/C7TC02117H
emission of Ir complexes, these devices displayed weak emission
range from 350 nm to 500 nm, which originate from the host
26DCzPPy (2,6ꢀbis(3ꢀ(carbazolꢀ9ꢀyl)phenyl)pyridine, 10 nm) /
TmPyPB (50 nm) / LiF (1 nm) / Al (100 nm). The optimal device
performances are achieved at doping level of 6% and 5% for
2
6DCzPPy attributed to the accumulation of holes and electrons
within the EML and few holes/electrons would recombine on
Ir(tfmpiq)
The EL spectra, luminanceꢀvoltageꢀcurrent density (LꢁVꢁJ)
curves, current efficiencyꢀluminance (ŋ ꢀL) curves, power
efficiencyꢀluminance (ŋ ꢀL) curves for G3 and G4 are shown in
2 2
(tpip) and Ir(tfmpqz) (tpip), respectively.
26DCzPPy molecules. And the Commission Internationale de
1’Eclairage (CIE) color coordinates of G1 and G2 are (0.575,
0.414) and (0.532, 0.456), respectively.
c
p
For the device G1, a maximum current efficiency (η
0.13 cd A (3.7 V) with a maximum external quantum
c
,
max) of
Fig. 5, and the crucial EL data are shown in Table 2. The peaks
of EL emission are 588 and 580 nm for G3 and G4, respectively,
and the emission spectra are almost invariant of the current
density (Fig. S6(c) and Fig. S6(d)) and there is no dependence on
concentration. The CIE color coordinates of G3 and G4 are
(0.579, 0.412) and (0.535, 0.453), respectively. From the Fig.
5(a), it is can be seen that the EL spectra are almost identical to
the PL spectra of the complexes, and the weak emissions in the
range of 350ꢀ500 nm were observed in the EL spectra of
doubleꢀEML devices caused by the emission of TcTa peaked at
385 nm.
ꢀ
1
2
efficiency (EQEmax) of 8.2%, a maximum power efficiency
ꢀ
1
p
(η ,max) of 19.32 lm W (3.5 V) and a maximum luminance (Lmax)
ꢀ
2
of 45 902 cd m were obtained. G2 exhibits much better
ꢀ
2
performances with a Lmax of 101 994 cd m at 10.0 V, a η
c
,
max of
ꢀ1
ꢀ
1
5
p
2.68 cd A , an EQEmax of 16.6%, and a η ,max of 42.87 lm W .
Moreover, G2 can remain high efficiency even at relatively high
luminance and the EL efficiency rollꢀoff is rather low. For
instance, the current efficiency for the device G2 still keeps as
ꢀ
1
ꢀ2
high as 46.00 cd A at the brightness of 1 000 cd m . The higher
PL efficiency (0.98) and better electron mobility (8.93ꢀ9.47 ×
Compared with the singleꢀEML devices, bot doubleꢀEML
devices displayed better EL performances and lower efficiency
ꢀ
6
2
ꢀ1 ꢀ1
ꢀ1 1/2
1
1
0 cm V s under the electric field from 1040 (V cm ) to
ꢀ
1 1/2
ꢀ1
300 (V cm )
)
of Ir(tfmpqz)
2
(tpip) than that of
rollꢀoff. For the device G3, a ηc,max of 22.39 cd A (3.9 V) with
ꢀ1
Ir(tfmpiq)
2
(tpip) would increase the device performances
an EQEmax of 10.3%, a ηp,max of 18.75 lm W (3.7 V) and a Lmax
ꢀ
2
greatly.
of 54 426 cd m were obtained. G4 exhibited much better
ꢀ
2
Generally, the doubleꢀEMLs device could achieve better
performances than the singleꢀEMLs device because a better
balance of carries and a wider recombination zone within EMLs
performances with a Lmax of 125 572 cd m (9.6 V), a ηc,max of
ꢀ1
ꢀ1
57.19 cd A , an EQEmax of 18.7%, and a ηp,max of 42.76 lm W .
Moreover, G4 can remain high efficiency even at relatively high
luminance and the EL efficiency rollꢀoff is rather low. For
instance, the current efficiency for the device G4 still keeps as
2
6
could be realized by the doubleꢀEMLs device. Thus, we
researched the doubleꢀEML devices G3 and G4 using
ꢀ
1
ꢀ2
Ir(tfmpiq)
with a structure of ITO / MoO
complex (x wt%): TcTa (10 nm) / Ir complex (x wt%):
2
(tpip) and Ir(tfmpqz)
2
(tpip) emitters, respectively,
high as 54.19 cd A at the brightness of 1 000 cd m and 48.17
ꢀ1
ꢀ2
3
(3 nm) / TAPC (50 nm) / Ir
cd A at the brightness of 5 000 cd m , respectively, suggesting
that the complex is a promising material in OLEDs.
5
0.12
0.10
1
1
1
0
1.0
0.8
0.6
0.4
0.2
0.0
(a)
(b)
G3
G4
G3
G4
4
0
0.08
0
0
0
0
.03
.02
.01
.00
3
0
0.06
2
10
0.04
3
00
350
400
450
500
1
0
1
0.02
0.00
300
350
400
450
500
550
600
650
700
4
6
8
10
Wavelength/nm
Voltage (V)
1
00
100
10
1
1
0
(c)
(
d)
G3
G4
G3
G4
1
0.1
0.1
0
2000
4000
6000
2
8000
10000
2000
4000
6000
8000
10000
2
Luminance (cd/m )
Luminance (cd/m )
Fig. 5. Characteristics of doubleꢀEML devices G3 and G4: (a) electroluminescence spectra ( 100 mA); (b) luminance – voltage – current density (L – V
J) curves; (c) current efficiency – luminance ( – L) curves; (d) power efficiency – luminance ( – L) curves.
–
η
c
η
p
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J. Mater. Chem. C, 2017, 00, 1-9 | 5

Journal of Materials Chemistry C
Page 6 of 11
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DOI: 10.1039/C7TC02117H
ꢀ
2
Because Ir(tfmpqz)
efficiency, further work was done to increase its performances. A
wide band gap trivalent europium complex Eu(DBM) phen
DBM = dibenzoylmethide, phen = 1,10ꢀphenanthroline) was
selected as a sensitizer codoped into the electron dominant EML
of the doubleꢀEMLs devices because that Eu(DBM) phen can
function as electron trappers due to its lowꢀlying energy levels,
which are helpful in balancing holes and electrons and in
broadening recombination zone. Furthermore, the matched triplet
2
(tpip) based device showed high
at y = 0.2 wt% with a maximum luminance of 129 466 cd m
ꢀ1
(10 V), a maximum current efficiency of 62.96 cd A , a
maximum external quantum efficiency of 20.2%, and
3
a
ꢀ
1
(
maximum power efficiency of 53.43 lm W (3.7 V). In addition,
the current efficiency for the device G5 still remain as high as
58.84 cd A at the brightness of 1 000 cd m and 53.27 cd A at
ꢀ
1
ꢀ2
ꢀ1
3
ꢀ
2
the brightness of 5 000 cd m , respectively.
From the device performances, it is can be concluded that the
introduction of 2,6ꢀbisꢀtrifluoromethylꢀpyridine and quinazoline
has definitely improved the electron mobility of the iridium
complexes. As a result, the recombination chance of electrons
and holes has been strengthened, which is beneficial to the
improvement of OLEDs’ performances. The devices structure of
double EMLs is also useful for the better device efficiency due to
the broad exciton formation zone. Furthermore, the efficiency
energy of Eu(DBM)
transfer from host to emitter. The device G5 with a structure of
ITO / MoO (3 nm) / TAPC (50 nm) / Ir(tfmpqz) (tpip) (5%):
TcTa (10 nm) / Eu(DBM) phen (y%): Ir(tfmpqz) (tpip) (5%):
6DCzPPy (10 nm) / TmPyPB (50 nm) / LiF (1 nm) / Al (100
nm) displayed better performances. The EL spectrum, LꢁVꢁJ, ŋ ꢀL
and ŋ ꢀL curves for G5 are show in Fig. 6, and the key EL data
are also showed in Table 2. The device performances are the best
3
phen is instrumental in facilitating energy
27
3
2
3
2
2
c
p
2
based on Ir(tfmpqz) (tpip) has been risen greatly thanks to the
sensitizer Eu(DBM)
3
phen.
5
10
0.12
(a)
(b)
0.10
4
10
0.08
3
2
1
1
0
0.06
0.04
10
0.02
10
0.00
300
350
400
450
500
550
600
650
700
4
6
8
10
Voltage (V)
Wavelength (nm)
100
100
(c)
(d)
1
0
10
1
1
0.1
0.1
0
2000
4000
6000 -
8000
10000
0
2000
4000
Lumminance
6000
8000
10000
2
-2
Lumminance (cd m )
(
cd m )
Fig. 6. Characteristics of the device G5: (a) electroluminescence spectra (100 mA); (b) luminance – voltage – current density (L – V– J) curves; (c)
current efficiency – luminance ( – L) curves; (d) power efficiency – luminance ( – L) curves.
η
c
η
p
Table 2. EL performances of G1 – G5.
a)
b)
c)
d)
f)
g)
ꢀ1
device
V
turnꢀon
L
max
η
c,max
η
c,L1000
EQEmax
η
p,max
CIE(x,y)
ꢀ
2
ꢀ1
ꢀ1
(
V)
(cd m )
(cd A )
(cd A )
(%)
(lm W )
G1
G2
G3
G4
G5
3.2
3.6
3.5
3.9
3.4
45902
101994
54426
20.13
52.68
22.39
57.19
19.32
46.00
17.27
54.19
58.84
8.2
16.61
42.87
18.03
42.76
53.43
0.575,0.414
0.532,0.456
0.579,0.412
0.535,0.453
16.6
10.3
18.7
125572
129466
62.96
20.2
0.545,0.450
a)
ꢀ2 b)
c)
d)
V
turnꢀon: turnꢀon voltage recorded at a luminance of 1 cd m .
L
max: maximum luminance.
c
η ,
max: maximum current efficiency.
ηc,L5000: current
ꢀ2
e)
ꢀ2 f)
g)
efficiency at 1 000 cd m .
efficiency.
η
c,L10000: current efficiency at 10 000 cd m . EQEmax: maximum external quantum efficiency.
p
η ,max: maximum power
6
2
| J. Mater. Chem. C, 2017, 00, 1-9
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Journal of Materials Chemistry C
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DOI: 10.1039/C7TC02117H
OLEDs fabrication and measurement
All OLEDs were fabricated on the preꢀpatterned ITOꢀcoated
Conclusions
ꢀ1
glass substrate with a sheet resistance of 15 ꢂ sq . The
In conclusion, we have prepared two bisꢀcyclometalatted iridium
complexes Ir(tfmpiq) (tpip) and Ir(tfmpqz) (tpip) with
ꢀ1
deposition rate for organic compounds is 1ꢀ2 Å s . The phosphor
and host were coꢀevaporated from two separate sources. The
cathode consisting of LiF/Al was deposited by evaporation of
2
2
1ꢀ(2,6ꢀbis(trifluoromethyl)pyridinꢀ4ꢀyl)isoquinoline
(tfmpiq)
and 4ꢀ(2,6ꢀbis(trifluoromethyl)pyridinꢀ4ꢀyl)quinazoline (tfmpqz)
as the main ligands and tetraphenylimidodiphosphinate (tpip)
as the ancilary ligand. Both complexes emit orangeꢀred
phosphorescence with high quantum efficiency and good
ꢀ1
LiF with a deposition rate of 0.1 Å s and then by evaporation of
ꢀ1
Al metal with a rate of 3 Å s . The effective area of the emitting
2
diode is 0.1 cm . The characteristics of the devices were
measured with a computer controlled KEITHLEY 2400 source
meter with a calibrated silicon diode in air without device
encapsulation. On the basis of the uncorrected PL and EL spectra,
the CIE coordinates were calculated using a test program of the
spectra scan PR650 spectrophotometer.
electron mobility, Ir(tfmpqz) (tpip) especially. Through the
2
comparison with the device using Ir(tfmpiq) (tpip), the device
2
using Ir(tfmpqz) (tpip) displays better EL performances and
2
lower efficiency rollꢀoff. Furthermore the device based on
Ir(tfmpqz) (tpip) with Eu(DBM) phen as sensitizer shows
2
3
ꢀ
2
better performances with a Lmax of 129 466 cd m , a η
of
c,max
Syntheses
ꢀ1
ꢀ1
6
2.96 cd A , an EQE of 20.2% and a ηp,max of 53.43 lm W ,
max
respectively. The results suggest that the Ir(III) complexes with
quinazoline units are potential orangeꢀred phosphorescent
materials for OLEDs.
All the reagents were used with commercial grade. The ligands
and complexes were synthesized under nitrogen atmosphere and
the synthetic routes were listed in Scheme 1.
General syntheses of ligands.
A stirred solution of
Experimental section
2,6ꢀbisꢀ(trifluoromethyl)pyridine (0.22 g, 10mmol) in diethyl
ether (20 mL) was cooled to ꢀ78 C. LDA (lithium
diisopropylamide, 6.0 mL, 10 mmol) was added over 20 min and
o
General information
1
3
stirred for 1 h, and then B(OPrꢀi) (2.89mL,12.4mmol) was
H NMR spectra were measured on a Bruker AM 500
added. The mixture was warmed to room temperature and stirred
for another 1 h. The pH was adjusted to 10 by the slow addition
of 10% aqueous NaOH solution (20 mL). After 1 hour, the
organic phase was acidified to pH = 4 by the dropwise addition
of 3 N HCl. The extraction with ethyl acetate and evaporation of
the organic phase gave the crude corresponding aryl boronic
acids. 1ꢀChloroisoquinoline / 4ꢀChloroquinazoline (10 mmol)
spectrometer. Electrospray ionization mass spectra (ESIꢀMS)
were obtained with ESIꢀMS (LCQ Fleet, Thermo Fisher
Scientific). Elemental analyses for C, H and N were performed
on an Elementar Vario MICRO analyzer. TGꢀDSC measurements
were carried out on a DSC 823e analyzer (METTLER). UVꢀvis
absorption and photoluminescence spectra were measured on a
Shimadzu UVꢀ3100 and a Hitachi Fꢀ4600 spectrophotometer at
and
dichloromethane (0.3 mmol) and the boronic acids were added in
0mL THF. After 20 mL of aqueous 2 N K CO was delivered,
bis(diphenylphosphion)
ferrocene
palladium
(II)
room
temperature,
respectively.
Cyclic
voltammetry
measurements were conducted on a MPIꢀA multifunctional
electrochemical and chemiluminescent system at room
5
2
3
o
+
the reaction mixture was heated at 70 C for 1 day under an
nitrogen atmosphere. The mixture was poured into water and
temperature using Fc /Fc as the internal standard and scan rate of
ꢀ1
0
.05 V s .
extracted with CH
purification (PE:EA
ꢀ(2,6ꢀbis(trifluoromethyl)pyridinꢀ4ꢀyl)isoquinoline
ꢀ(2,6ꢀbis(trifluoromethyl)pyridinꢀ4ꢀyl)quinazoline.
-(2,6-Bis(trifluoromethyl)pyridin-4-yl)isoquinoline. 40%
2 2
Cl (10 mL × 3 times). Finally, silica column
X-ray crystallography
=
10:1
)
gave
the
1
4
and
Xꢀray crystallographic measurements of the single crystals were
carried out on a Bruker SMART CCD diffractometer (Bruker
Daltonic Inc.) using monochromated Mo Kα radiation (λ =
1
1
yield. H NMR (400 MHz, CDCl
3
) δ 8.69 (d, J = 5.6 Hz, 1H),
.26 (s, 2H), 8.00 (d, J = 8.3 Hz, 1H), 7.94 (dd, J = 8.5, 0.8 Hz,
H), 7.81 (ddd, J = 8.2, 5.9, 1.2 Hz, 2H), 7.69 (ddd, J = 8.3, 6.9,
0
.71073 Å) at room temperature. Cell parameters were retrieved
8
1
1
28
using SMART software and refined using SAINT program in
order to reduce the highly redundant data sets. Data were
collected using a narrowꢀframe method with scan width of 0.30°
in ω and an exposure time of 5 s per frame. Absorption
+
+
8 6 2
.2Hz, 1H). MS(ESI) m/z calcd for C16H F N : 352.06 [M] ,
+
found: 353.06 [M+H] .
-(2,6-Bis(trifluoromethyl)pyridin-4-yl)quinazoline. 30%
4
2
9
corrections were applied using SADABS supplied by Bruker.
1
yield. H NMR (400 MHz, CDCl
.27 (d, J = 8.5 Hz, 1H),8.06 (ddd, J = 8.4, 6.9, 1.3Hz, 1H),7.96
dd, J = 8.4, 0.6Hz, 1H),7.78 (ddd, J = 8.3, 7.0, 1.1 Hz, 1H). MS
3
) δ 9.49 (S, 1H),8.30 (S, 2H),
The structures were solved by Patterson methods and refined by
8
2
fullꢀmatrix leastꢀsquares on
F
using the program
(
(
30
SHELXSꢁ2014. The positions of metal atoms and their first
coordination spheres were located from directꢀmethods Eꢀmaps,
other nonꢀhydrogen atoms were found in alternating difference
Fourier syntheses and leastꢀsquares refinement cycles and during
the final cycles refined anisotropically. Hydrogen atoms were
placed in calculated position and refined as riding atoms with a
+
+
ESI) m/z calcd. for
15 7 6 3
C H F N [M] : 343.05, found
+
3
44.06[M+H] .
General syntheses of iridium complexes. A mixture of IrCl
1 mmol) and tfmpiq or tfmpqz (2.5 mmol) in 2ꢀethoxyethanol
3
(
and water (20 mL, 3:1, v/v) was refluxed for 24 h. After cooling,
the solid precipitate was filtered to give the crude cyclometalated
Ir(III) chloroꢀbridged dimer. Then, the slurry of crude
uniform value of Uiso
.
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J. Mater. Chem. C, 2017, 00, 1-12 | 7

Journal of Materials Chemistry C
Page 8 of 11
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DOI: 10.1039/C7TC02117H
chloroꢀbridged dimer (0.2 mmol) and Ktpip (0.5 mmol) in
ꢀethoxyethanol (20 mL) was refluxed for 24 h. The solvent was
evaporated at low pressure and the mixture was poured into
water and extracted with CH Cl (10 mL × 3 times), and then
chromatographed to give complexes Ir(tfmpiq) (tpip) and
(tpip), which were further purified by sublimation in
2011, 133, 10543; (f) K. Y. Lu, H. H. Chou, C. H. Hsieh, Y. H. O.
Yang, H. R. Tsai, H. Y. Tsai, L. C. Hsu, C. Y. Chen, I. C. Chen and
C. H. Cheng, Adv. Mater., 2011, 23, 4933; (g) C.ꢀH. Fan, P. Sun,
T.ꢀH. Su and C.ꢀH. Cheng, Adv. Mater., 2011, 23, 2981; (h) S. Lee,
S. O. Kim, H. Shin, H. J. Yun, K. Yang, S. K. Kwon, J. J. Kim and
Y. H. Kim, J. Am. Chem. Soc., 2013, 135, 14321; (i) X. L. Yang,
N. Sun, J. S. Dang, Z. Huang, C. L. Yao, X. B. Xu, C. L. Ho, G. J.
2
2
2
2
Ir(tfmpqz)
vacuum.
2
1
Ir(tfmpiq)
.89 (d, J = 6.6 Hz, 2H), 8.71 (d, J = 8.6 Hz, 2H), 8.51 (s, 2H),
.85ꢀ7.59 (m, 10H), 7.44ꢀ7.30 (m, 6H), 6.93 (ddd,
16.7,11.8,6.7 Hz, 6H), 6.67 (td, J = 7.4,1.3 Hz, 2H), 6.49 (td, J
7.7,3.3 Hz, 4H). MS(ESI) m/z calcd for C56
2
(tpip). 46% yield. H NMR (400 MHz, CDCl3) δ
Zhou, D. G. Ma, X. Zhao and W. Y. Wong, J. Mater. Chem. C
2013, , 3317; (j) H. Sasabe, H. Nakanishi,Y. Watanabe,S. Yano,
M. Hirasawa, Y.J. Pu and J. Kido, Adv. Funct. Mater., 2013, 23
5550; (k) H.ꢀH. Chou, Y.ꢀK. Li, Y.ꢀH. Chen, C.ꢀC. Chang, C.ꢀY.
Liao and C.ꢀH. Cheng, ACS Appl. Mater. Interfaces, 2013, , 6168;
(l) V. K. Rai, M. Nishiura, M. Takimoto and Z. Hou, J. Mater.
Chem. C, 2014, , 5317; (m) H. Cao, H. Sun, Y. Yin, X. Wen, G.
Shan, Z. Su, R. n. Zhong, W. Xie, P. Li and D. Zhu, J. Mater.
Chem. C, 2014, , 2150; (n) A.Graf, P. Liehm, C.Murawski, S.
Hofmann, K. Leo and M. C. Gather, J. Mater. Chem. C, 2014,
0298; (o) X. Xu, X. Yang, J. Dang, G. Zhou, Y. Wu, H. Li and
W.ꢀY. Wong, Chem. Commun., 2014, 50, 2473; (p) X. Yang, G.
Zhou and W.ꢀY. Wong, J. Mater. Chem. C, 2014, , 1760.
,
8
7
=
=
1
J
,
H
34
F
12IrN
5
2
O P
2
:
5
+
+
1
291.16 [M] , found 1292.17 [M+H] . Anal. Calcd. For
C
54
H
32
F12IrN
7
O
2
P
2
: C 52.05, H 2.65, N 5.42. Found: C 51.95, H
2
2
.71, N 5.45.
2
1
Ir(tfmpqz) (tpip). 27% yield. H NMR (400 MHz, CDCl3) δ
2
2
,
9
7
6
2
.69 (s, 2H), 8.61 (d, J = 11.7 Hz, 4H), 7.93 (d, J = 5.7 Hz, 4H),
.88ꢀ7.82 (m, 2H), 7.71 (dd, J = 11.6, 7.3 Hz, 4H), 7.40 (d, J =
.8 Hz, 6H), 6.96 (dd, J = 12.3, 7.5 Hz, 4H), 6.64 (t, J = 7.1 Hz,
H), 6.53 (d, J = 6.9 Hz, 4H). MS(ESI) m/z calcd for
1
2
2
3
W. S. Jeon, T. J. Park, S. Y. Kim, R. Pode, J. Jang and J. H. Kwon,
Appl. Phys. Lett., 2008, 93, 063303.
+
+
C H F IrN O P : 1293.15 [M] , found 1294.17 [M+H] . Anal.
5
4
32 12
7
2 2
Calcd. For C H F IrN O P : C 50.11, H 2.49, N 7.58. Found:
5
4
32 12
7
2 2
(a) A. Tsuboyama, H. Iwawaki, M. Furugori, T. Mukaide, J.
Kamatani, S. Igawa, T. Moriyama, S. Miura, T. Takiguchi, S.
C 49.94, H 2.97, N 7.71.
Okada, M. Hoshino and K. Ueno, J. Am. Chem. Soc., 2003, 125
2971; (b) S. Okada, K.Okinaka, H. Iwawaki, M. Furugori, M.
Hashimoto, T. Mukaide, J. Kamatani, S. Igawa, A. Tsuboyama, T.
Takiguchi and K. Ueno, Dalton Trans., 2005, , 1583; (c) G. Zhou,
,
Acknowledgements
1
This work was supported by the Major State Basic Research
Development Program (2013CB922101), the National Natural
Science Foundation of China (21371093, 91433113, 21301095),
the Natural Science Foundation of Jiangsu Province
9
C. L. Ho, W. Y. Wong, Q. Wang, D. Ma, L. Wang, Z. Lin, T. B.
Marder and A. Beeby, Adv. Funct. Mater., 2008, 18, 499; (d) J. C.
Deaton, R. H. Young, J. R. Lenhard, M. Rajeswaran and S. Huo,
Inorg. Chem., 2010, 49, 9151; (e) C. L. Ho, L. C. Chi, W. Y. Hung,
W. J. Chen, Y. C. Lin, H. Wu, E. Mondai, G. J. Zhou, K. T. Wong
and W. Y. Wong, J. Mater. Chem. C, 2012, 22, 215; (f) C. L. Ho, B.
Yao, B. Zhang, K. L. Wong, W. Y. Wong, Z. Xie, L. Wang and Z.
Lin, J. Organomet. Chem., 2013, 730, 144; (g) G. M. Li, D. X. Zhu,
(
(
BK20130054), Youth Innovation Promotion Association CAS
2013150), and Strategic Priority Research Program of the
Chinese Academy of Sciences (XDB20000000).
Notes and references
1
State Key Laboratory of Coordination Chemistry, Jiangsu Key
T. Peng, Y. Liu, Y. Wang and M. R. Bryce, Adv. Funct. Mater.
,
Laboratory of Advanced Organic Materials, Collaborative Innovation
Center of Advanced Microstructures, School of Chemistry and Chemical
Engineering, Nanjing University, Nanjing 210093, P. R. China, *eꢁmail:
yxzheng@nju.edu.cn
2
014, 24, 7420; (h) G. J. Li, J. Ecton, B. O’Brien and J. Li, Org.
Electron., 2014, 15, 1862; (i) X. B. Xu, X. L. Yang, Y. Wu, G. J.
Zhou, C. Wu and W. Y. Wong, Chem. Asian J., 2015, 10, 252; (j)
X. L. Yang, X. B. Xu, J. S. Dang, G. J. Zhou, C. L. Ho and W. Y.
Wong, Inorg. Chem., 2016, 55, 1720; (k) J. Lin, N. Y. Chau, J. L.
Liao, W. Y. Wong, C. Y. Lu, Z. T. Sie, C. H. Chang, M. A. Fox, P.
J. Low, G. H. Lee and Y. Chi, Organometallics, 2016, 35, 1813; (l)
X. J. Liu, B. Yao, Z. L. Zhang, X. F. Zhao, B. H. Zhang, W. Y.
2
State Key Laboratory of Rare Earth Resource Utilization, Changchun
Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun
1
#
†
30022, P. R. China
Han and Cui have the same contributions to this paper
Electronic Supplementary Information (ESI) available. Parameters
Wong, Y. X. Cheng and Z. Y. Xie, J. Mater. Chem. C, 2016,
787.
4,
associated with the single crystal diffraction data, selected bond
lengths and angles of Ir(tfmpiq) (tpip) and Ir(tfmpqz) (tpip)
The EL characteristics of single devices G1 and G2.
5
2
2
.
4
5
6
(a) C.ꢀT. Chen, Chem. Mater., 2004, 16, 4389; (b) S.D. Cummings
and R. Eisenberg, J. Am. Chem., Soc., 1996, 118, 1949.
1
1
(a) S. Lamansky, P. Djurovich, D. Murphy, F. AbdelꢀRazzaq, H.
C.ꢀL. Ho, H. Li and W.ꢀY. Wong, J. Organomet. Chem., 2014, 751,
E. Lee, C. Adachi, P. E. Burrow, S. R. Forrest and M. E.
Thompson, J. Am. Chem. Soc., 2001, 123, 4304; (b) J. J. Kim, Y.
You, Y. S. Park, J. J. Kim and S. Y. Park, J. Mater. Chem., 2009,
261.
(a) Y.ꢀJ. Su, H.ꢀL. Huang, C.ꢀL. Li, C.ꢀH. Chien, Y.ꢀT. Tao, P.ꢀT.
Chou, S. Datta and R.ꢀS. Liu, Adv. Mater., 2003, 15, 884; (b) C.L.
Li, Y.J. Su, Y.T. Tao, P.T. Chou, S. Datta and R.S. Liu, Adv. Funct.
Mater., 2005, 15, 387.
1
9
, 8347; (c) Z. Q. Chen, Z. Q. Bian and C. H. Huang, Adv. Mater.
010, 22, 1534; (d) S. M. Chen, G. P. Tan, W. Y. Wong and H. S.
2011, 21 3785; (e) J. M.
FernándezꢀHernández, C. H. Yang, J. I. Beltrán, V. Lemaur, F.
Polo, R. Fröhlich, J. Cornil and L. D. Cola, J. Am. Chem. Soc.
,
2
Kwok, Adv. Funct. Mater.
,
,
7
(a) C. Adachi, M.A. Baldo, S.R. Forrest, S. Lamansky, M.E.
Thompson, R.C. Kwong, Appl. Phys. Lett., 2001, 78, 1622; (b) P.
Coppo, E.A. Plummer, L.D. Cola, Chem. Commun., 2004, 1774.
,
8
2
| J. Mater. Chem. C, 2017, 00, 1-9
017
This journal is © The Royal Society of Chemistry

Page 9 of 11
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View Article Online
DOI: 10.1039/C7TC02117H
8
9
H.ꢀC. Ting, Y.ꢀM. Chen, H.ꢀW. You, W.ꢀY. Hung, S.ꢀH. Lin, A.
Chaskar, S.ꢀH. Chou, Y. Chi, R.ꢀH. Liu, K.ꢀT. Wong, J. Mater.
Chem., 2012, 22, 8399.
H. Y. Li, L. Zhou, M. Y. Teng, Q. L. Xu, C. Lin, Y. X. Zheng, J. L.
Zuo, H. J. Zhang and X. Z. You, J. Mater. Chem. C, 2013, , 560;
1
(e) C. C. Wang, Y. M. Jing, T. Y. Li, Q. L. Xu, S. Zhang, W. N. Li,
Y. X. Zheng, J. L. Zuo, X. Z. You and X. Q. Wang, Eur. J. Inorg.
Chem., 2013, 5683; (f) M. Y. Teng, S. Zhang, Y. M. Jin, T. Y. Li,
X. Liu, Q. L. Xu, C. Lin, Y. X. Zheng, L. Wang and J. L. Zuo, Dyes
Pigm., 2014, 10, 105; (g) Q. L. Xu, X. Liang, S. Zhang, Y. M. Jing,
X. L., G. Z. Lu, Y. X. Zheng and J. L. Zuo, J.Mater. Chem. C,2015,
(a) G.ꢀJ. Zhou, W.ꢀY. Wong, B. Yao, Z. Xie, L. Wang, Angew.
Chem. Int. Ed., 2007, 46, 1149; (b) C.ꢀL. Ho, W.ꢀY. Wong, Z.ꢀQ.
Gao. C.ꢀH. Chen, K.ꢀW. Cheah, B. Yao, Z. Xie, Q. Wang, L. Wang,
X.ꢀM. Yu, H.ꢀS. Kwok, Z. Lin, Adv. Funct. Mater., 2008, 18, 319.
(a) G.ꢀJ. Zhou, W.ꢀY. Wong, B. Yai, Z. Xie, L. Wang, J. Mater.
Chem., 2008, 18, 1799; (b) J.H. Yao, C. Zhen, K.P. Loh, Z.ꢀK.
Chen, Tetrahedron, 2008, 64, 10814.
1
1
0
1
3
, 3694.
14
(a) H.ꢀH. Chou and C.ꢀH. Cheng, Adv. Mater., 2010, 22, 2468; (b)
S. O. Jeon, S. E. Jang, H. S. Son and J. Y. Lee, Adv. Mater., 2011,
23, 1436.
(a) D.H. Kim, N.S. Cho, H.ꢀY. Oh, J.H. Yang, W.S. Jeon, J.S. Park,
M.C. Suh, J.H. Kwon, Adv. Mater., 2011, 23, 2721. (b) F.ꢀI. Wu,
H.ꢀJ. Su, C.ꢀF. Shu, L. Luo, W.ꢀG. Diau, C.ꢀH. Cheng, J.ꢀP. Duan,
G.ꢀH. Lee, J. Mater. Chem., 2005, 15, 1035. (c) S.ꢀJ. Lee, J.ꢀS.
Park, M. Song, I.A. Shin, Y.ꢀI. Kim, J.W. Lee, J.ꢀW. Kang, Y.ꢀS.
Gal, S. Kang, J.Y. Lee, S.ꢀH. Jung, H.ꢀS. Kim, M.ꢀY. Chae, S.ꢀH.
Jin, Adv. Funct. Mater., 2009, 19, 2205. (d) J. Ding, J. Lü, Y.
15
16
17
Y. T. Tao, C. L. Yang and J. G. Qin, Chem. Soc. Rev., 2011, 40,
2943.
S. Bettington, M. Tavasli, M. R. Bryce, A. Beeby, H. AlꢀAttar and
A. P. Monkman, Chem. Eur. J., 2007, 13, 1423.
–
(a) M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M.
A. Robb, J. R. Cheeseman, G. Scalmani, V. Barone, B. Mennucci,
G. A. Petersson, H. Nakatsuji, M. Caricato, X. Li, H. P. Hratchian,
A. F. Izmaylov, J. Bloino, G. Zheng, J. L. Sonnenberg, M. Hada,
M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T.
Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven, J. A.
Montgomery Jr., J. E. Peralta, F. Ogliaro, M. Bearpark, J. J. Heyd,
E. Brothers, K. N. Kudin, V. N. Staroverov, R. Kobayashi, J.
Normand, K. Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar,
J. Tomasi, M. Cossi, N. Rega, J. M. Millam, M. Klene,J. E. Knox,
J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E.
Stratmann, O. Yazyev, A. J. Austin, R. Cammi, C. Pomelli, J. W.
Ochterski, R. L. Martin, K. Morokuma, V. G. Zakrzewski, G. A.
Voth, P. Salvador, J. J. Dannenberg, S. Dapprich, A. D. Daniels, O.
Farkas, J. B. Foresman, J. V. Ortiz, J. Cioslowski and D. J. Fox,
Gaussian 09, Revision A.01, Gaussian, Inc., Wallingford, CT, 2009;
(b) C. T. Lee, W. T. Yang and R. G. Parr, Phys. Rev. B: Condens.
Matter Mater. Phys., 1988, 37, 785; (c) A. D. Becke, J. Chem.
Cheng, Z. Xie, L. Wang, X. Jing, F. Wang, Adv. Funct. Mater.
,
2
008, 18, 2754. (e) J. Qiao, L. Duan, L. Tang, L. He, L. Wang, Y.
Qiu, J. Mater. Chem., 2009, 19, 6573. (f) C.ꢀL. Ho, L.ꢀC. Chi,
W.ꢀY. Hung, W.ꢀJ. Chen, Y.ꢀC. Lin, H. Wu, E. Mondal, G.ꢀJ. Zhou,
K.ꢀT. Wong, W.ꢀY. Wong, J. Mater. Chem., 2012, 22, 215. (g) M.
Tavasli, T.N. Moore, Y. Zheng, M.R. Bryce, M.A. Fox, G.C.
Griffiths, V. Jankus, H.A. AlꢀAttar, A.P. Monkman, J. Mater.
Chem., 2012. 22, 6419. (h) M. Zhu, Y. Li, S. Hu, C. Li, C. Yang, H.
Wu, J. Qin, Y. Cao, Chem. Commun., 2012, 48, 2695. (i) G.ꢀJ.
Zhou, C.ꢀL. Ho, W.ꢀY. Wong, Q. Wang, D. Ma, L. Wang, Z. Lin,
T.B. Marder, A. Beeby, Adv. Funct. Mater., 2008, 18, 499. (j) G.ꢀJ.
Zhou, Q. Wang, W.ꢀY. Wong, D. Ma, L. Wang, Z. Lin, J. Mater.
Chem., 2009, 19, 1872. (k) J. Li, R. Wang, R. Yang, W. Zhou, X.
Wang, J. Mater. Chem. C, 2013, 1, 4171. (l) B.X. Mi, P.F. Wang,
Z.Q. Gao, C.S. Lee, S.T. lee, H.L. Hong, X.M. Chen, M.S. Wong,
P.F. Xia, K.W. Cheah, C.H. Chen, W. Huang, Adv. Mater., 2009,
2
1
1
5
, 339. (m) J.P. Duan, P.P. Sun, C.H. Cheng, Adv. Mater., 2003,
, 224. (n) Q. Mei, L. Wang, Y. Guo, J. Weng, F. Yan, B. Tian, B.
Phys., 1993, 98, 5648; (d) P. J. Hay, J. Phys. Chem., A, 2002, 106
,
Tong, J. Mater. Chem., 2012, 22, 6878. (h) Y.ꢀJ. Pu, R.E. Harding,
1634; (e) S. Chiodo, N. Russo and E. Sicilia, J. Chem. Phys., 2006,
125, 104107; (f) M. Cossi, N. Rega, G. Scalmani and V. Barone, J.
Comput. Chem., 2003, 24, 669.
S.G. Stevenson, E.B. Namdas, C. Tedeschi, J.P.J. Markham, R.J.
Rummings, P.L. Burn, I.D.W. Samuel, J. Mater. Chem., 2007, 17
,
4
255. (i) H. Fukagawa, T. Shimizu, H. Hanashima, Y. Osada, M.
18
19
A. F. Rausch, M. E. Thompson and H. Yersin, Inorg. Chem., 2009,
48, 1928.
Suzuki, H. Fujikake, Adv. Mater., 2012, 24, 5099. (j) E. Rossi, L.
Murphy, P.L. Brothwood, A. Colombo, C. Dragonetti, D. Roberto,
(a) A. P. Wilde and R. J. Watts, J. Phys. Chem., 1991, 95, 622; (b)
M. G. Colombo, T. C. Brunold, T. Riedener, H. U. Gudel, M.
Fortsch and H. B. Burgi, Inorg. Chem., 1994, 33, 545.
(a) J. Kalinowski, W. Stampor, J. Mezyk, M. Cocchi, D. Virgili, V.
Fattori and P. Di Marco, Phys. Rev. B: Condens. Matter Mater.
Phys., 2002, 66, 235321; (b) W. S. Jeon, T. J. Park, S. Y. Kim, R.
Pode, J. Jang and J. H. Kwon, Appl. Phys. Lett., 2008, 93, 063303.
S. C. Tse, H. H. Fong and S. K. So, J. Appl. Phys., 2003, 94, 2033.
(a) H. Scher and E. W. Montroll, Phys. Rev. B: Solid State, 1975,
12, 2455; (b) A. J. Pal, R. Osterbacka, K. M. Kallman and H. Stubb,
Appl. Phys. Lett., 1997, 71, 228.
R. Ugo, M. Cocchi, J.A.G. Williams, J. Mater. Chem., 2011, 21
,
1
5501. (k) C. Borek, K. Hanson, P.I. Djurovich, M.E. Thompson,
K. Aznavour, R. Bau, Y.R. sun, S.R. Forrest, J. Brooks, L.
Michalski, J. Brown, Angew. Chem. Int. Ed., 2007, 46, 1109. (l)
T.ꢀC. Lee, J.ꢀY. Hung, Y. Chi, Y.ꢀM. Cheng, G.ꢀH. Lee, P.ꢀT.
20
Chou, C.ꢀC. Chen, C.ꢀ H. Chang, C.ꢀC. Wu, Adv. Funct. Mater.
009, 19, 2639.
(a) S. Heun and P. M. Borsenberger, Chem. Phys., 1995, 200, 245;
b) H. H. Fong, K. C. Lun and S. K. So, Chem. Phys. Lett., 2002,
53, 407.
(a) Y. C. Zhu, L. Zhou, H. Y. Li, Q. L. Xu, M. Y. Teng, Y. X.
Zheng, J. L. Zuo, H. J. Zhang and X. Z. You, Adv. Mater., 2011, 23
041; (b) M. Y. Teng, S. Zhang, S. W. Jiang, X. Yang, C. Lin, Y.
,
2
21
22
1
1
2
3
(
3
23
24
25
J. Lee, N. Chopra, S.ꢀH. Eom, Y. Zheng, J. Xue, F. So and J. Shi,
Appl. Phys. Lett., 2008, 93, 123306.
,
4
S.ꢀJ. Su, T. Chiba, T. Takeda and J. Kido, Adv. Mater., 2008, 20,
X. Zheng, L. Y. Wang, D. Wu, J. L. Zuo and X. Z. You, Appl.
Phys. Lett., 2012, 100, 073303; (c) Q. L. Xu, C. C. Wang, T. Y. Li,
M. Y. Teng, S. Zhang, Y. M. Jing, X. Yang, W. N. Li, C. Lin, Y. X.
Zheng, J. L. Zuo and X. Z. You, Inorg. Chem., 2013, 52, 4916; (d)
2125.
M. Ikai, S. Tokito, Y. Sakamoto, T. Suzuki and Y. Taga, Appl.
Phys. Lett., 2001, 79, 156.
This journal is © The Royal Society of Chemistry 2017
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2
6
(a) X. Zhao, L. Zhou , Y. Jiang, R. Cui, Y. Li and H. Zhang, Dyes and
Pigments, 2016, 130, 148; (b) Y. Li, L. Zhou, Y. Jiang, R. Cui, X.
Zhao, Y. Zheng, J. Zuo and H. Zhang, RSC Adv., 2016, 6, 63200; (c) Y.
Li, L. Zhou, R. Cui, Y. Jiang, X. Zhao, W. Liu, Q. Zhu, Y. Cui and H.
Zhang, RSC Adv., 2016, 6, 71282
2
2
2
3
7
8
9
0
L. Zhou, L. Li, Y. Jiang, R. Cui, Y. Li, X. Zhao and H. Zhang, ACS
Appl. Mater. Interfaces,2015, 7, 16046.
SAINTꢁPlus, version 6.02, Bruker Analytical Xꢀray System,
Madison, WI, 1999.
G. M. Sheldrick, SADABS An empirical absorption correction
program, Bruker Analytical Xꢁray Systems, Madison, WI, 1996.
G. M. Sheldrick, SHELXTLꢁ2014, Universität of Göttingen,
Göttingen, Germany, 2014.
1
0 | J. Mater. Chem. C, 2017, 00, 1-9
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Graphical abstract
100
-
2
-1
Lmax: 129 466 cd m ; ηc,max: 62.96 cd A
-1
EQEmax: 20.2%; ηmax: 53.43 lm W
10
Low efficiency roll-off.
F3C
N
N
CF3
O
O
P
P
1
Ir
N
N
2
0.1
0
1000
2000
3000
4000
5000
-2
Lumminance (cd m )
Two orange-red iridium complexes with high quantum yields and good
electron mobility were applied in efficient OLEDs showing a maximum
-
2
luminance of 129 466 cd m , a maximum current efficiency and a
-
1
-1
maximum power efficiency of 62.96 cd A and 53.43 lm W ,
respectively, with low efficiency roll-off.