Star-shaped trinuclear cyclometalated platinum(II) complexes as single-component emitters in white-emitting PLEDs

Article abstract of DOI:10.1002/asia.201200182

Two star-shaped phosphorescent small molecules, Ph-3FPt(pic) and 4Ph-3FPt(pic), are single-component emitters in polymer white-light-emitting diodes (WPLEDs) that are comprised of three blue-light-emitting phosphorescent chromophores of FPt(pic) and are a

Full text of DOI:10.1002/asia.201200182

DOI: 10.1002/asia.201200182
Star-Shaped Trinuclear Cyclometalated Platinum(II) Complexes as Single-
Component Emitters in White-Emitting PLEDs
Danyan Shi, Yafei Wang,* Yu Liu, Zhiyong Zhang, Jian Luo, Juan He, Qing Chen,
Gangtie Lei, and Weiguo Zhu*[a]
Abstract: Two star-shaped phosphores-
cent small molecules, Ph-3FPt(pic) and
4Ph-3FPt(pic), are single-component
emitters in polymer white-light-emit-
ting diodes (WPLEDs) that are com-
prised of three blue–light-emitting
phosphorescent chromophores of FPt-
corresponding mono- or dinuclear plat-
inum complexes, this class of star-
shaped homotrinuclear cyclometalated
platinum(II) complexes exhibited con-
trollable excimer emission. Stable
white/near-white emission was obtained
in single-emissive-layer PLEDs by
using the Ph-3FPt(pic) or 4Ph-3FPt-
(pic) as a single dopant and a blend of
G
ACHTUNGTRENNUNG
E
ACHTUNGTRENNUNG
poly(vinylcarbazole) and 2-(4-biphen-
yl)-5-(4-tert-butyl-phenyl)-1,3,4-oxadia-
zole as a host matrix at dopant concen-
trations of 1–4 wt.%. Our results pro-
vide an efficient way to control exci-
mer formation and to obtain a single-
component emitter for use in
WPLEDs.
ACHTUNGTRENNUNG
Keywords: dendrimers · molecular
devices · optoelectronic properties ·
platinum · WPLEDs
a
chain, respectively. Compared to their
Introduction
type of device has an inherent problem in color stability be-
cause the blue-light emitter has a shorter lifetime than the
green- and red-light emitters. The second approach involves
employing a single-component emitter with a wide spectro-
scopic emission in the host matrix.[19,20] By utilizing this class
of single-component emitters, the SEL devices can readily
exhibit white or near-white emissions.[21–23] Owing to the
high quantum efficiency that results from the harvest of
both single and triplet excitons, the development of single-
component phosphorescent emitters have received the most
attention. Until now, the single-component phosphorescent
emitters that have been reported have mostly been copoly-
mers with different phosphors,[20] small molecules with
a mono- or di-nuclear platinum complex unit,[24–26] and a bi-
metallic assembly that contains both a red-light-emitting eu-
ropium complex and a blue-light-emitting iridium complex
or both blue-light-emitting iridium and -platinum com-
plexes.[27,28] However, star-shaped, phosphorescent small
molecules with homotrinuclear cyclometalated platinum(II)
complexes have not yet been presented as single-component
emitters in the SEL WPLEDs.
Since Kido and co-workers reported the first organic white-
light-emitting diode in 1994,[1] organic and polymeric white-
light-emitting diodes (WOLEDs/WPLEDs) have attracted
tremendous attention in both academic and industrial com-
munities owing to their intrinsic properties, such as low driv-
ing voltages and their glare-free nature, thereby providing
homogenous illumination and potential applications in
energy-saving solid-state lighting.[2–4] To date, various
WOLEDs and WPLEDs have been reported with single-
emissive-layer (SEL)-,[1,5,6] multiple-emissive-layer (MEL)-
[7,8]
,
tandem-,[9–11] and microcavity structures.[12,13] Of these
white-light-emitting devices, SEL-based devices can be
made with a simple process technique and are considered as
a promising class of commercial lighting sources.
There are two commonly used approaches to construct
the emitting layer in SEL white-light-emitting devices: The
first approach involves the use of multiemitters with various
emissive colors in the same host matrix.[1,14–18] However, this
To further study the influence of molecular structure on
the emission of the single-component phosphorescent emit-
ters and to obtain stable SEL WPLEDs we designed and
synthesized two star-shaped homotrinuclear cyclometalated
[a] D. Shi, Dr. Y. Wang, Dr. Y. Liu, Z. Zhang, J. Luo, J. He, Q. Chen,
Prof. G. Lei, Prof. W. Zhu
Department of Chemistry
Key Lab of Environment-Friendly Chemistry and
Application in Ministry of Education
Xiangtan University, Xiangtan 411105 (China)
Fax : (+86)731-58292251
platinum(II) complexes, Ph-3FPt
which FPt(pic) is a blue-light-emitting phosphorescent chro-
mophore of platinum(II), [(4,6-difluorophenyl)-pyridinato-
N,C2’](picolinate), and three FPt(pic) units are attached
ACHTUGTNREN(UNG pic) and 4Ph-3FPtACHTUNGTRENNUNG(pic), in
AHCTUNGTRENNUNG
E-mail: zhuwg18@126.com
AHCTUNGTRENNUNG
qiji830404@hotmail.com
onto a benzene-1,3,5-trioxy- or 1,3,5-(4-oxyphenyl)benzene
core through hexyloxy linkages, respectively. We expected
that the unconjugated hexyloxy linkage between the FPt-
Supporting information for this article, including detailed information
on the synthesis of the other materials and their property measure-
ments, is available on the WWW under http://dx.doi.org/10.1002/
asia.201200182.
AHCTUNGTREG(NNUN pic) chromophore and the aryl core controls intramolecular
Chem. Asian J. 2012, 00, 0 – 0
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energy transfer in the trinuclear
molecules. The introduction of
the star-shaped molecular struc-
ture can not only improve film-
formation and dispersibility but
it can also efficiently tune the
aggregation state for the homo-
trinuclear molecules in the host
matrix. In addition, changing
the aryl core can tune the inter-
molecular interactions and, fur-
thermore, allows a study of the
relationship between molecular
structure and properties. We ex-
pected that this class of star-
shaped homotrinuclear cyclo-
metalated platinum(II) com-
plexes should exhibit a wide
spectroscopic emission and
become a new class of promis-
ing single-component emitters
for use in SEL WPLEDs with
a more stable white-light emis-
sion. The synthetic route to Ph-
3FPtACTHNUTRGNEN(UG pic) and 4Ph-3FPtACHTUNGTRENNUNG(pic) is
shown in Scheme 1. Their pho-
tophysical, electrochemical, and
electroluminescent properties
were studied. The results
showed that both Ph-3FPt
ACHTUNGTRENNUNG(pic)
and 4Ph-3FPt(pic) presented
AHCTUNGTRENNUNG
excellent film-formation and
dispersibility in poly(N-vinyl-
carbazole) and 2-(4-biphenyl)-
5-(4-tert-butylphenyl)-1,3,4-oxa-
diazole (PVK+PBD). Stable
near-white-light emission was
realized in the SEL PLEDs by
using Ph-3FPt
3FPt(pic) as
nent emitter and PVK+PBD as
host matrix at different
dopant concentrations (1–
ACHTUNGTRENNUNG
G
a
a
Scheme 1. Synthesis of Ph-3FPtACTHNUGRTNENUG(pic) and 4Ph-3FPtACHTUNGTNER(NUGN pic).
4 wt.%). Compared to the
linear homodinuclear cyclome-
talated platinum(II) complexes,
this class of star-shaped homotrinuclear cyclometalated plat-
inum(II) complexes exhibited significantly restrained exci-
mer emissions in the neat films under photoexcitation.
Therefore, it was easier to obtain near-white-light emission
in the SEL PLEDs of the star-shaped homotrinuclear cyclo-
metalated platinum(II) complexes as single-component
emitters than in their linear homodinuclear analogues.
Abstract in Chinese:
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Star-Shaped Trinuclear Cyclometalated Platinum(II) Complexes
Table 1. Photophysical and electrochemical properties of Ph-3FPtACTHNUTRGENN(UG pic) and 4Ph-3FPtACHTUNTGREN(NUGN pic).
Results and Discussion
[d]
[f]
[g]
[h]
Complexes
UV/Vis (emax
)
PL
EHOMO
ELUMO
Ered
DE
Td
Ra
Synthesis and Characterization
[nm][a]
[nm][a] [nm][b] Ff[c] [eV]
[eV]
[V]
[eV] [8C] [nm]
Compounds 1 and 4 were ob- Ph-3FPt
tained by using a similar ether-
forming reaction in which N,N-
N
312
352
G
487,
527
425,
487,
600
425,
484,
525
0.48 À5.44
0.30 À5.52
À2.64
À2.57
À1.70 2.80
À1.76 2.95
191
225
0.934
0.397
(pic) 263
N
487,
523
dimethylformamide (DMF) was
used as the solvent (instead of
acetone) to improve the solubil-
ity of the reactants. Methyl pi-
324
354
[a] UV/Vis spectra were recorded in CH2Cl2 (1ꢁ10À3 m) at 298 K; emax values are given in dm3 molÀ1 cmÀ1
[b] Measured in the neat film. [c] Fir(pic) in degassed CH2Cl2 at 298 K (Fr =0.60) was used as a reference; cor-
.
AHCTUNGTRENNUNG
rections were made owing to changes in the refractive index of the solvent. [d] EHOMO =(ELUMOÀDE) (eV).
[f] ELOMO =À(Ered+4.34) (eV). [g] The band gap (DE) was derived from a solution in CH2Cl2 by UV/Vis spec-
troscopy. [h] Td is either the decomposition temperature or the onset temperature for 5% weight loss under
a N2 atmosphere.
colinate derivatives
2 and 5
were synthesized in a William-
son ether-formation reaction by
using cesium carbonate as an
alkali and acetone as the sol-
vent. Picolinic acid derivative 3 was obtained by hydrolysis
of methyl picolinate derivative 2 in an aqueous solution of
sodium hydroxide and tetrahydrofuran (THF). Picolinic acid
derivative 7 was obtained from a Suzuki coupling reaction
that was accompanied by a domino hydrolysis reaction. Star-
shaped homotrinuclear cyclometalated PtII complexes Ph-
transfer transitions (1MLCT and 3MLCT), respectively.
Compared to Ph-3FPt(pic), 4Ph-3FPt(pic) exhibits an addi-
tional intense absorption band at 266 nm owing to the effect
of the 1,3,5-(4-oxytriphenyl)benzene core. This result implies
that changing the aryl core has little effect on the electron
transition absorption.
G
ACHTUNGTRENNUNG
3FPt
G
E
The photoluminescence (PL) spectra of Ph-3FPt
4Ph-3FPt(pic), and FPt
(pic) in CH2Cl2 at 10À3 m are shown
in Figure 1 and their PL data are also listed in Table 1. Ph-
3FPt(pic), 4Ph-3FPt(pic), and FPt(pic) exhibit almost identi-
ACHTUNGTRENNUNG(pic),
the chloride group in dimer 8 with their corresponding pico-
linic acid derivatives according to our previously reported
procedure.[29] The resulting molecules were confirmed by
NMR spectroscopy and elemental analysis.
G
ACHTUNGTRENNUNG
G
E
ACHTUNGTRENNUNG
cal PL spectra, with an intense emission peak at 487 nm and
a shoulder at 525 nm, which is assigned to a mixing of the
singlet and triplet MLCT transitions based on literature re-
ports.[32] To explore the influence of concentration on the
emission, we measured the PL spectra with increasing con-
The UV/Vis absorption spectra of Ph-3FPt
(pic), and FPt(pic) in CH2Cl2 are shown in Figure 1. For
comparison, the UV/Vis absorption spectrum of their mono-
nuclear counterpart, FPt(pic), in CH2Cl2 is also shown.
G
centrations from 10À6 m to 10À3 m in CH2Cl2 for Ph-3FPt
and 4Ph-3FPt(pic) (see the Supporting Information, Fig-
ACHTUNGTRENNUNG(pic)
AHCTUNGTRENNUNG
ure S1). Significantly different PL profiles are observed with
increasing concentration for both star-shaped homotrinu-
clear cyclometalated PtII complexes. Gradually red-shifted
Their UV/Vis absorption data are listed in Table 1. An in-
tense high-lying absorption band (around 240 nm) and two
moderate low-lying absorption peaks (about 324 nm and
emissions are shown for Ph-3FPtACTHUNRTGENNUG(pic) and 4Ph-3FPtACHTUNGTRENNUNG(pic)
352 nm) are observed for Ph-3FPt
G
with increasing concentrations. However, compared to the
previously reported platinum complexes, these star-shaped
homotrinuclear cyclometalated PtII complexes exhibited less
excimer emission. Therefore, the homotrinuclear cyclometa-
lated PtII complexes, especially the one that contained the
1,3,5-tri(oxyphenyl)benzene core, presented lower molecular
aggregation and controllable excimer emission.
counterpart, FPt
ACHTUNGTRENNUNG
is assigned to the ligand-centered (LC) p p* electron transi-
tion and the low-lying absorption peaks are assigned to
spin-allowed and spin-forbidden metal-to-ligand charge-
In addition, significantly different PL profiles are also ob-
served for both star-shaped homotrinuclear cyclometalated
PtII complexes in their neat films (see the Supporting Infor-
mation, Figure S2). Two intense, high-lying emission bands
(around 425–485 nm) and a moderately intense, low-lying
band (around 600 nm) are observed in the PL spectra of the
Ph-3FPt
ACHUTGTNRENNUG(pic) neat film. Compared to Ph-3FPtACHTUNTGREN(NUNG pic), 4Ph-
3FPt(pic) presented significantly weaker (and even almost
AHCTUNGTRENNUNG
disappeared) low-lying emission in the neat film. Unlike the
star-shaped homotrinuclear cyclometalated PtII complexes,
its mononuclear counterpart displayed a distinctly different
PL profile with an intense low-lying band under these condi-
tions. It is obvious that both Ph-3FPt
ACHTUNGTREN(NUNG pic) exhibit significantly weaker excimer emission than FPt-
ACHTUNGTREN(NUGN pic) and 4Ph-3FPt-
Figure 1. UV/Vis and PL spectra of various platinum complexes in dilute
CH2Cl2 (10À3 m) at 298 K.
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Yafei Wang, Weiguo Zhu et al.
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ACHTUNGTRENNUNG(pic). Therefore, the star-shaped molecular structure is avail-
able for controlling excimer emission in the neat films.
Electrochemical Properties
Their electrochemical behaviors were investigated by using
cyclic voltammetry (CV) and the CV data are listed in
Thermal Properties and Dispersibility
Table 1. The irreversible onset reduction potentials (Ered
)
The thermal stabilities of the homotrinuclear cyclometalated
platinum(II) complexes were evaluated by thermogravimet-
ric analysis (TGA) under a stream of N2 at a scanning rate
of 208CminÀ1 (Figure 2). The decomposition temperatures
were in the range À1.70 to À1.76 V. The oxidation potentials
(Eox) were in the range 1.10 to 1.18 V, according to the for-
mula of Ered =EoxÀEg, in which Eg is typically estimated
from the low-lying absorption edge data. The HOMO and
the LUMO energy levels (EHOMO and ELUMO, respectively)
(Td) at 5% weight loss were 1918C for Ph-3FPt
2258C for 4Ph-3FPt(pic). Therefore, both platinum(II) com-
plexes presented high thermal stability.
ACHTUNGTRENN(UNG pic) and
N
were calculated by using the following equations: EHOMO
(Eox+4.34), ELUMO =À(Ered+4.34). Therefore, the HOMO
and LUMO energy levels were located at À5.44 eV and
À2.64 eV for Ph-3FPt(pic) and at À5.52 eV and À2.57 eV
for 4Ph-3FPt(pic), respectively. Compared to the reported
values of mononuclear counterpart FPt
=
ÀACHTUNGTRENNUG
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
(pic),[26] these star-
shaped homotrinuclear cyclometalated PtII complexes dis-
played lower energy-gaps and higher HOMO and LUMO
energy levels.
Electroluminescence Properties
To investigate the electroluminescence (EL) properties of
these platinum(II) complexes, single-emissive-layer devices
were fabricated with a structure of ITO/PEDOT:PSS (40–
50 nm)/emitting layer (70–75 nm)/CsF (1.5 nm)/Al (100 nm),
in which indium tin oxide (ITO) and poly(3,4-ethylene-diox-
ythiophene)-poly(styrenesulfonate) (PEDOT:PSS; both pur-
chased from Bayer AG) are used as the anode and hole-in-
jection layer, as well as CsF and Al as the electron-injection
layer and cathode, respectively. The emitting layer consists
of the star-shaped trinuclear cyclometalated platinum(II)
Figure 2. TGA curves of Ph-3FPt
ACHUTGTNRENNUG(pic) and 4Ph-3FPtCAHTUNGTREN(NUGN pic) under a stream
of nitrogen with a scanning rate of 208CminÀ1
.
To clarify their dispersibility in the polymer matrix, films
of PVK+PBD were made that were doped with Ph-3FPt-
ACHTUNGTRENNUNG(pic) and 4Ph-3FPtACHTUTGNREN(NUNG pic) at a doping concentration of
8 wt.%. The surface morphologies were recorded by atomic
force microscopy (AFM) and are shown in Figure 3. Rough-
ness values of Ra =0.934 nm and 0.397 nm are observed for
complexes, Ph-3FPt
PVK+PBD host matrix. The doping concentrations of Ph-
3FPt(pic) and 4Ph-3FPt(pic) are 1 wt.%, 2 wt.%, 4 wt.%,
and 8 wt.%. The EL spectra of the Ph-3FPt(pic)-doped and
4Ph-3FPt(pic)-doped devices with different dopant concen-
ACHTUNGTRENN(UNG pic) or 4Ph-3FPt (pic), as well as the
G
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
the films that were doped with Ph-3FPt
(pic) and 4Ph-3FPt-
trations from 1–8 wt.% at 14 V are shown in Figure 4. Their
corresponding CIE chromaticity diagrams are also shown.
Three distinct peaks (about 440 nm, 484 nm, and 588 nm)
are observed in their EL spectra: The emission peak at
about 440 nm is attributed to the host matrix, the emission
peak at 484 nm is assigned to the monomolecular platinum
complexes, and the emission peak at 588 nm is attributed to
the aggregate/excimers. Near-white-light emissions from
these devices are exhibited at dopant concentrations of 1–
4 wt.% at 14 V. Their CIE coordinates vary from (0.30,
ACHTUNGTRENNUNG(pic), respectively. This result means that both star-shaped
homotrinuclear cyclometalated PtII complexes exhibited
good dispersibility in the PVK+PBD matrix.
0.28) to (0.38, 0.41) for the Ph-3FPt
ACHTUNGTRENNUNG
from (0.34, 0.33) to (0.40, 0.45) for the 4Ph-3FPtAHCTUNGTRENNUNG
devices with increasing dopant concentration under this ap-
plied voltage. To understand the influence of the applied
voltage on the EL spectra, we measured the EL spectra and
their CIE 1931 chromaticity under various applied voltages
from 14 V to 17 V for the Ph-3FPt
ACHTUNGTREN(NUNG pic)-doped and 4Ph-
3FPt(pic)-doped devices at 1 wt.% dopant concentration
(Figure 5). Obviously, both devices exhibited stable white-
light emission at different applied voltages. The CIE coordi-
AHCTUNGTRENNUNG
Figure 3. AFM images of PVK+PBD films that were doped with the ho-
motrinuclear cyclometalated PtII complexes (70 nm) at 8 wt.% doping
concentration: a) Ph-3FPtACHTNUTRGENN(UG pic), b) 4Ph-3FPtACHTUNGTERN(NUGN pic).
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Star-Shaped Trinuclear Cyclometalated Platinum(II) Complexes
nates are located in the white-
light region and show a minor
change from (0.30, 0.28) to
(0.36, 0.36) for the Ph-3FPt-
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
device with increasing applied
voltages. Thus, both star-shaped
homotrinuclear cyclometalated
PtII complexes exhibit promis-
ing
applications
in
SEL
WPLEDs.
The
Ph-3FPtAHCTUNGTREG(NNUN pic)-doped
device exhibited better perfor-
mance than 4Ph-3FPtACHTNUTGRNEUNG(pic). The
highest luminance (375 cdmÀ2)
and the maximum current effi-
ciency (0.1 cdAÀ1) were ob-
tained in the Ph-3FPtACHTUNGTRENNUNG(pic)-
doped device at 1 wt.% doping
concentration. Although these
preliminary results are inferior
to those of recently reported
white-light-emitting OLEDs, it
is the first time in which a class
of star-shaped homotrinuclear
Figure 4. EL spectra and CIE 1931 chromaticity diagrams of Ph-3FPt
PLEDs (b) at different dopant concentrations (1–8 wt.%).
ACHUTGTNRENNUG(pic)-doped (a) and 4Ph-3FPtACHTUNGTNER(NUGN pic)-doped
cyclometalated
complexes are used as single-
component emitters in
platinum(II)
WPLEDs. As expected, com-
pared to their corresponding
mono- and dinuclear cyclome-
talated PtII complexes,[26] the
star-shaped molecular structure
plays a positive role in control-
ling excimer emission. Further-
more, the core structure has
a remarkable effect on the EL
properties of the resulting com-
plexes.
Conclusions
Two star-shaped homotrinuclear
cyclometalated
complexes, Ph-3FPt
4Ph-3FPt(pic), were synthe-
platinum(II)
AHCTUNGTRENNUNG
AHCTUNGTRENNUNG
sized. Their star-shaped molec-
ular structure can effectively
control the excimer emissions
for this class of homotrinuclear
cyclometalated
complexes.
platinum(II)
Near-white-light
emissions were achieved in
these SEL-based PLEDs. This
Figure 5. EL spectra and CIE 1931 chromaticity diagrams of Ph-3FPtACTHNUGTRENNUG(pic)-doped (a) and 4Ph-3FPtACHTUNGTRENN(UGN pic)-doped
PLEDs (b) at 1 wt.% dopant concentration under various applied voltages.
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Yafei Wang, Weiguo Zhu et al.
FULL PAPER
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All solvents were carefully dried and distilled prior to use. Commercially
available reagents were used without further purification unless other-
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and were monitored by thin-layer chromatography (TLC). Flash column
chromatography and preparative TLC were carried out by using silica gel
from Merck (200–300 mesh).
Preparation of Ph-3FPt
ACHTUNGTRENNUNG(pic)
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A mixture of [{(dfppy)PtCl}2] (0.2 g, 0.2 mmol; dfppy=4,6-difluorophe-
nylpyridine), compound (60 mg, 0.1 mmol), and sodium carbonate
3
(0.4 g, 2.8 mmol) were stirred in 2-ethoxyethanol (15 mL) under a N2 at-
mosphere at 1008C for 24 h. After cooling to RT, the mixture was ex-
tracted with CH2Cl2 (3ꢁ30 mL) and the mixed organic layer was dried
over anhydrous MgSO4 and filtered. The filtrate was evaporated to
remove the solvent and the residue was purified by column chromatogra-
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phy on silica gel (EtOAc/THF, 1:1) to afford Ph-3FPtACTHNUTRGNE(NUG pic) as a yellow
solid (54 mg, 36.1%). 1H NMR (400 MHz, CDCl3): d=9.10–9.09 (d, J=
2.8 Hz, 3H), 8.66–8.65 (d, J=4.0 Hz, 3H), 7.95–7.84 (m, 6H), 7.68–7.56
(m, 6H), 7.13–7.09 (m, 3H), 6.83–6.81 (m, 3H), 6.59–6.55 (m, 3H), 6.08–
6.06 (d, J=6.0 Hz, 3H), 4.19–4.17 (t, J=8.0, 6.0 Hz, 6H), 3.97–3.95 (t, J=
8.0, 6.4 Hz, 6H), 2.06–1.96 (m, 6H), 1.81–1.80 (m, 6H), 1.19–0.89 (m,
6H), 0.89–0.87 ppm (m, 6H); 13C NMR (100 MHz, CDCl3, TMS): d=
172.01, 163.10, 160.10, 158.71, 157.43, 156.42, 150.05, 140.32, 137.34,
135.93, 130.22, 127.42, 124.68, 122.01, 121.95, 120.78, 112.03, 105.43, 92.22,
68.97, 29.76, 26.02 ppm; elemental analysis calcd (%) for
C75H66F6N6O12Pt3: C 46.37, H 3.42, N 4.33; found: C 45.78, H 3.63, N 4.18.
[17] C. L. Yang, X. W. Zhang, H. You, L. Y. Zhu, L. Q. Chen, L. N. Zhu,
Y. T. Tao, D. G. Ma, Z. G. Shuai, J. G. Qin, Adv. Funct. Mater. 2007,
17, 651.
[18] S. L. Gong, Y. H. Chen, C. L. Yang, C. Zhong, J. H. Qin, D. G. Ma,
Adv. Mater. 2010, 22, 5370.
[19] J. Liu, Y. Cheng, Z. Xie, Y. Geng, L. Wang, X. Jing, F. Wang, Adv.
Mater. 2008, 20, 1357.
[20] J. Jiang, Y. Xu, W. Yang, R. Guan, Z. Liu, H. Zhen, Y. Cao, Adv.
Mater. 2006, 18, 1769.
[21] B. W. D’Andrade, J. Brooks, V. Adamovich, M. E. Thompson, S. R.
Forrest, Adv. Mater. 2002, 14, 1032.
[22] E. L. Williams, K. Haavisto, J. Li, G. E. Jabbour, Adv. Mater. 2007,
19, 197.
[23] J. Kalinowski, M. Cocchi, D. Virgili, V. Fattori, J. A. G. Williams,
Adv. Mater. 2007, 19, 4000.
[24] Y. F. Wang, Y. Liu, X. S. Li, H. R. Qi, M. X. Zhu, L. Wang, G. T.
Lei, Q. Wei, W. G. Zhu, J. B. Peng, Y. Cao, Org. Electron. 2010, 11,
1954.
[25] V. Adamovich, J. Brooks, A. Tamayo, A. M. Alexander, P. I. Djuro-
vich, B. W. D’Andrade, C. Adachi, S. R. Forrest, M. E. Thompson,
New J. Chem. 2002, 26, 1171.
[26] Y. F. Wang, X. P. Deng, Y. Liu, M. J. Ni, M. Liu, T. Tan, X. S. Li, W.
Zhu, Y. Cao, Tetrahedron 2011, 67, 2118.
[27] X. S. Li, Y. Liu, J. Luo, Z. Y. Zhang, D. Y. Shi, Q. Chen, Y. F. Wang,
J. He, J. M. Li, G. T. Lei, W. G. Zhu, Dalton Trans. 2012, 41, 2972.
[28] P. Coppo, M. Duati, V. N. Kozhevnikov, J. W. Hofstraat, L. D. Cola,
Angew. Chem. 2005, 117, 1840; Angew. Chem. Int. Ed. 2005, 44,
1806.
Preparation of 4Ph-3FPt
ACHTUNGTNER(NUNG pic)
4Ph-3FPt(pic) was prepared according to the same procedure as that of
ACHTUNGTRENNUNG
Ph-3FPt(pic) (see above) and was obtained as a red solid (76 mg,
ACHTUNGTRENNUNG
58.3%). 1H NMR (400 MHz, CDCl3): d=9.31–9.29 (d, J=5.6 Hz, 3H),
8.77–8.76 (d, J=4.2 Hz, 3H), 8.12–8.10 (d, J=8.0 Hz, 3H), 8.00–7.98 (m,
3H), 7.81–7.79 (d, J=8.8 Hz, 6H), 7.66–7.64 (d, J=8.0 Hz, 9H), 7.57–
7.54 (m, 3H), 7.28–7.27 (m, 3H), 7.09–7.06 (m, 6H), 6.73–6.71 (m, 3H),
4.34–4.31 (t, J=6.4, 6.0 Hz, 6H), 4.17–4.14 (t, J=6.0, 6.0 Hz, 6H), 2.12–
2.10 (m, 6H), 2.00–1.98 (m, 6H), 1.55–1.53 (m, 6H), 1.41–1.38 ppm (m,
6H); 13C NMR (100 MHz, CDCl3, TMS): d=158.73, 158.14, 149.99,
133.54, 129.05, 128.20, 128.15, 125.00, 122.07, 121.90, 121.69, 114.84,
110.02, 99.65, 70.27, 67.81, 30.12, 29.73, 29.12, 28.74, 25.64 ppm; elemental
analysis calcd (%) for C93H78F6N6O12Pt3: C 51.45, H 3.62, N 3.87; found:
C 51.12, H 3.82, N 3.70.
[29] Z. Y. Hu, Y. F. Wang, D. Y. Shi, H. Tang, X. S. Li, L. Wang, W. G.
Zhu, Y. Cao, Dyes Pigm. 2010, 86, 166.
Acknowledgements
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[31] F. Lafolet, S. Welter, Z. L. D. Cola, J. Mater. Chem. 2005, 15, 2820.
[32] A. F. Rausch, H. H. Homeier, P. I. Djurovich, M. E. Thompson, H.
Yersin, Proc. SPIE 2007, 6655, 66550F.
Financial support is acknowledged from the National Natural Science
Foundation of China (50973093, 20872124, 21172187, and 20772101), the
Specialized Research Fund and the New Teachers Fund for the Doctoral
Program of Higher Education of China (20094301110004 and
200805301013), the Scientific Research Fund of Hunan Provincial Educa-
tion Department (10A119, 11CY023, and 10B112), and the Postgraduate
Science Foundation for Innovation in Hunan Province (CX2011B263).
Received: February 26, 2012
Published online: && &&, 0000
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www.chemasianj.org
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Asian J. 0000, 00, 0 – 0
ÝÝ These are not the final page numbers!

FULL PAPER
Emissive Materials
Danyan Shi, Yafei Wang,* Yu Liu,
Zhiyong Zhang, Jian Luo, Juan He,
Qing Chen, Gangtie Lei,
Weiguo Zhu*
&&&& — &&&&
Star-Shaped Trinuclear Cyclometalated
Platinum(II) Complexes as Single-
Component Emitters in White-Emit-
ting PLEDs
Starry eyed: Two star-shaped homotri-
layer PLEDs. Stable white emissions
were obtained in the PLEDs at various
doping concentrations from 1–4 wt.%
owing to the controllable excimer
nuclear cyclometalated PtII complexes,
Ph-3FPtACHTUNGTRENNUNG(pic) and 4Ph-3FPtACHTUNGTNER(NUGN pic), were
synthesized and served as single-com-
ponent emitters in single-emissive-
emission of this class of PtII complexes.
Chem. Asian J. 2012, 00, 0 – 0
ꢀ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
7
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These are not the final page numbers! ÞÞ