High colour rendering index and colour stable hybrid white efficient OLEDs with a double emitting layer structure using a single phosphorescence dopant of heteroleptic platinum complexes

Article abstract of DOI:10.1039/c4tc01791a

Four heteroleptic platinum complexes (FPtXND) bearing 4-hydroxy-1,5-naphthyridine derivatives functionalized with dimethyl (X = mm), phenoxy (X = OPh), piperidine (X = pp), or carbazole (X = Cz) units as one ligand (XND) and 2-(2,4-difluorophenyl)pyridine as the other common ligand (F) were newly synthesized and characterized. The crystal structures of FPtOPhND and FPtCzND were determined by single-crystal X-ray diffraction crystallography. Although they have a short plane-to-plane packing distance of 3.62 and 3.39 A, respectively, both platinum complexes have different molecular packing patterns, which affect their photoluminescence (PL) in solution and electroluminescence (EL) in the solid state. Due to the contribution from both monomers and excimers/aggregates, all of the platinum complexes exhibited broad and red-shifted PL in concentrated solutions as well as in doped thin films. In the monochromatic organic lighting diode (OLED) testing, FPtXND doped in 4,4′-di(9H-carbazol-9-yl)-1,1′-biphenyl (CBP) exhibited greenish yellow or orange yellow EL, of which FPtOPhND has the highest EL efficiency mainly due to its high solution PL quantum yield of 21%. Hybrid white OLEDs were first achieved with a single emitting layer configuration, of which highly fluorescent blue N,N′-di-1-naphthalenyl-N,N′-diphenyl-[1,1′:4′,1″:4″,1-quaterphenyl]-4,4-diamine (4P-NPD) was used as the host material for all four platinum complexes. To improve the performance of the FPtOPhND-based hybrid white OLEDs, double emitting layer configurations were adopted with CBP and 4P-NPD as the host material. Virtually voltage independent, a white EL having CIE_x,y (0.33, 0.31) and a CRI as high as 91 was obtained. The maximum EL efficiency of 11.8%, 25.9 cd A^-1, or 11.6 lm W^-1 was acquired with FPtOPhND doped in the double emitting layer configuration of an OLED.

Full text of DOI:10.1039/c4tc01791a

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Journal of Materials Chemistry C
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DOI: 10.1039/C4TC01791A
Journal Name
RSCPublishing
ARTICLE
High colour rendering index and colour stable hybrid
white efficient OLEDs with a double emitting layer
structure using single phosphorescence dopant of
heteroleptic platinum complexes
Cite this: DOI: 10.1039/x0xx00000x
Received 00th January 2012,
Accepted 00th January 2012
Anurach Poloek,abc Chiao-Wen Lin,a Chin-Ti Chen,*a and Chao-Tsen Chen*c
DOI: 10.1039/x0xx00000x
Four heteroleptic platinum complexes (FPtXND) bearing 4ꢀhydroxyꢀ1,5ꢀnaphthyridine derivatives
functionalized with dimethyl ( X = mm), phenoxy (X = OPh), piperidine (X = pp), or carbazole (X = Cz)
unit as one ligand (XND) and 2ꢀ(2,4ꢀdifluorophenyl)pyridine as the other common ligand (F) were
newly synthesized and characterized. The crystal structures of FPtOPhND and FPtCzND were
determined by the singleꢀcrystal Xꢀray diffraction crystallography. Although having short planeꢀtoꢀplane
packing distance of 3.62 and 3.39 Å, respectively, both platinum complexes have different molecular
packing pattern, which affects the photoluminescence (PL) in solution and electroluminescence (EL) in
solid state. Due to the contribution from both monomers and excimer/aggregate, all platinum complexes
exhibited broad and redꢀshifted PL in concentrated solution as well as in doped thin film. In the
monochromatic organic lighting diode (OLED) testing, FPtXND doped in 4,4'ꢀdi(9Hꢀcarbazolꢀ9ꢀyl)ꢀ
1,1'ꢀbiphenyl (CBP) exhibited greenish yellow or orange yellow EL, of which FPtOPhND has the
highest EL efficiency mainly due to its high solution PL quantum yield of 21%. Hybrid white OLEDs
were first achieved with single emitting layer configuration, of which highly fluorescent blue N,N′ꢀdiꢀ1ꢀ
naphthalenylꢀN,N′ꢀdiphenylꢀ[1,1′:4′,1″:4″,1‴ꢀquaterphenyl]ꢀ4,4‴ꢀdiamine (4PꢀNPD) was used as the host
material for all four platinum complexes. To improve the performance of the FPtOPhNDꢀbased hybrid
white OLEDs, double emitting layer configuration were adopted with CBP and 4PꢀNPD as the host
material, respectively. Virtually voltage independent, a white EL having CIEx,y (0.33, 0.31) and a CRI as
high as 91 were obtained. Maximum EL efficiency of 11.8%, 25.9 cd Aꢀ1, or 11.6 lm Wꢀ1 has been
acquired with FPtOPhND doped in double emitting layer configuration of OLED.
www.rsc.org/
(high colour rendering index, CRI) WOLEDs.2 Nonetheless, the
success of such WOLEDs hinges on complicated device structure
Introduction
which is difficult to be fabricated. Moreover, blue phosphorescent
dopants still suffer from poor stability and frustration of finding
suitable host materials due to their intrinsically high triplet energy
(ET) over 2.7 eV of iridium(III) bis[(4,6ꢀdifluorophenyl)ꢀpyridinatoꢀ
N,C2]picolinate (FIrpic).3 To simplify WOLED fabrication, utilizing
only two complementary phosphorescent emitters, either blue and
yellow or blue and orange,4,5 is a reasonable alternative to achieve
white electroluminescence (EL). In order to achieve stable WOLEDs
and yet having easy fabrication, fluorescence (F)ꢀphosphorescence
(P) hybrid WOLEDs have been demonstrated before.6 More
recently, Leo et al. have reported a breakthrough of FꢀP hybrid
WOLED by harnessing the separation of singlet and triplet excitons.7
In the past few decades, white organic lightꢀemitting diodes
(WOLEDs) have drawn increasing attention because of their
potential applications in full colour flatꢀpanel displays and solidꢀstate
lighting.1 In order to achieve white light emission, two or three
emitters are generally required in device configuration. Particularly,
three phosphorescent dopants (red, green, blue) have been employed
to realise high electroluminescence (EL) efficiency and high quality
a Institute of Chemistry, Academia Sinica, Taipei, Taiwan 11529,
Republic of China. Eꢀmail: chintchen@gate.sinica.edu.tw;
Fax: +886 2 27831237; Tel: +886 2 27898542
b Nano Science and Technology Program, Taiwan International Graduate
Program (TIGP), Academia Sinica and National Taiwan University
c Department of Chemistry, National Taiwan University, Taipei, Taiwan
10617
High
performance
N,N′ꢀdiꢀ1ꢀnaphthalenylꢀN,N′ꢀdiphenylꢀ
[1,1′:4′,1″:4″,1‴ꢀquaterphenyl]ꢀ4,4‴ꢀdiamine (4PꢀNPD) was used as
the blue fluorescent material and the host for orange phosphorescent
dopant Ir(MDQ)2(acac). 4PꢀNPD has a high photoluminescence (PL)
quantum yield (92%) and sufficient triplet energy (ET) of 2.3 eV for
orange phosphorescent dopant. Since then, there have been
numerous reports for such FꢀP hybrid WOLEDs and most of them
This journal is © The Royal Society of Chemistry 2013
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are based on iridium complexes.8 Although FꢀP hybrid WOLEDs Cassis method using Meldrum’s acid in the first step and followed
with iridium complexes exhibit relatively high EL efficiency, by heatꢀassisted intramolecular cyclization, has been developed
insufficient CRI less than 80 is always the results. To improve the before by us (Scheme 3).12 Similar to many others, the new
quality (i.e., CRI) of FꢀP hybrid WOLED with a simple device heteroleptic platinum complexes were prepared in two steps as
configuration, platinum complex is a better choice than iridium shown in Scheme 3. It involved the cyclometallation of K2PtCl4
complex.9 This is because platinum complexes, molecules having with 2ꢀ(2,4ꢀdifluorophenyl)pyridine (F) to form the Pt ꢁꢀdichloroꢀ
square planar geometry, are prone to aggregation in solid state, bridged dimer (FPtCl)2.13 The subsequent reaction of (FPtCl)2 with
which often displays broadened EL spectrum due to its monomeric mmND, OPhND, ppND, and CzND yielded heteroleptic platinum
and excimeric emission.10 Thus, WOLEDs with high CRI can be complexes FPtmmND, FPtOPhND, FPtppND, and FPtCzND,
easily obtained when combined with a blue fluorescent host material. respectively. Details of synthetic of platinum complexes are given in
Accordingly, we have reported that high performance FꢀP hybrid experimental section.
WOLEDs can be achieved with a new heteroleptic platinum
complex FPtmND (Scheme 1) and the blue fluorescent host 4Pꢀ
NPD.11 From such simple structure FꢀP WOLEDs, external quantum
efficiency (EQE) or power efficiency (PE) as high as 11.9% or 12.1
lm Wꢀ1has been obtained and a CRI as high as 89 was acquired as
well. However, such a FꢀP hybrid device showed a warm white EL
with CIEx,y (0.41, 0.41) and its colour stability needs to be
demonstrated. Therefore, there is still room for improvement on such
hybrid white OLEDs.
Scheme 2 Synthesis of pyridiylamine derivatives 4OPh, 4pp, and 4Cz.
Reagents, conditions and yields: (a) H2SO4, KNO3, 100 oC, 92%; (b)
POCl3, toluene, 110 oC, 90%; (c) phenol, K2CO3, DMF, 80 oC, 95%;
(d) piperidine, EtOH, 94%; (e) carbazol, Cs2CO3, MeCN, 82 oC,
o
62%; (f) SnCl2·2H2O, HCl, MeOH, 80 C, 85%; (g) cat. 10% Pd/C,
H2, THF, rt, 85%; (h) N2H4, cat. 10% Pd/C, EtOH/THF = 1:1, 92%.
Scheme
1 Chemical structures of parent FPtmND and the
functionalized platinum complexes (FPtXND).
In this contribution, we report the synthesis and characterization
as well as photophysical, and electrochemical properties of a new
class of heteroleptic platinum complexes FPtXND, where X =
mmND, OPhND, ppND and CzND (Scheme 1). In the present
study, hydroxylꢀ1,5ꢀnapthyridine ligands were functionalized with
dimethyl, phenoxy, piperidino, or carbazolyl unit with the aim of
tuning emission energy in solution and in solid state. Interestingly,
all these platinum complexes display varied emission from greenish
yellow to red wavelength due to its monomer and aggregate/excimer
emission. We have found that the colour of which could be varied by
controlling the concentration of dopant and the type of host materials
in solid thin film. Different electroluminescent profiles were
achieved with platinum complexes doped in either conventional host
4,4'ꢀdi(9Hꢀcarbazolꢀ9ꢀyl)ꢀ1,1'ꢀbiphenyl (CBP) or the new host (for
platinum complexes) 4PꢀNPD. Hybrid white OLEDs were developed
with a simple device configuration by utilizing monomer and
excimer/aggregate emission of platinum complexes together with
blue fluorescence of 4PꢀNPD.
Scheme 3 Synthetic route of a series of 8ꢀhydroxyꢀ1,5ꢀnaphthyridine
ligands XND and the corresponding platinum complexes FPtXND.
X-ray crystallography
Single crystals of FPtOPhND and FPtCzND were grown from
dichloromethane/methanol solution. The molecular structure and
molecular packing structure were acquired by singleꢀcrystal Xꢀray
diffraction analysis.14 Fig. 1 and 2 display the ORTEP diagram and
stacking diagram of FPtOPhND and FPtCzND, respectively. The
molecular structure of both FPtOPhND and FPtCzND exhibits a
distorted square planar geometry with the two coordinating nitrogen
atoms in trans conformation. The corresponding PtꢀN, PtꢀC and PtꢀO
distances are not so different for both complexes (see figure caption
of both Fig. 1 and 2). However, the stacking diagrams show very
different molecular packing of FPtOPhND and FPtCzND. For
FPtOPhND, each molecule stacks almost on top of each other (Fig.
1 bottom left and right), having ~66.81o horizontal rotation along the
stacking axis to avoid the eclipse configuration among adjacent
molecules. A single uniformed PtꢀPt distance of 3.54 Å is found for
the molecular stacking of FPtOPhND. An average planeꢀtoꢀplane
Results and discussion
Synthesis
Pyridiylamine derivatives 4OPh, 4pp, and 4Cz are required in the
preparation of heteroleptic platinum coordinated ligand mmND,
OPhND, ppND, or CzND. They were readily prepared by adopting
the literature procedure (Scheme 2) and ESI contains the synthetic
detail and structural characterization data. In synthesizing hydroxylꢀ
1,5ꢀnapthyridine derivatives, a facile twoꢀstep synthesis, namely
2 | J. Name., 2012, 00, 1-3
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DOI: 10.1039/C4TC01791A
distance of 3.62 Å is calculated for FPtOPhND. Such PtꢀPt distance distances, 3.17Å (sky blue lines) and 5.42 Å (golden yellow lines)
is within a range of 3.15 to 3.76 Å reported by other dimeric (bottom). Selected bond lengths (Å): PtꢀN(2) = 2.048, PtꢀO(1) =
structure of platinum complexes.15 Very differently, FPtCzND 2.081, PtꢀN(1) = 1.998, PtꢀC(11) = 2.000. In the stacking diagram,
molecules are stacked pair wise and each stacking pair is slided side all hydrogen atoms are removed for clarity.
way to form a slope packing from one direction (Fig. 2 bottom left).
Similar to that of FPtOPhND, a ~44.85o horizontal rotation to avoid
UV-Visible absorption spectroscopic analysis
the eclipse configuration in each stacked pair. For each stacked pair
of FPtCzND, the PtꢀPt distance is 3.17 Å (5.42 Å of the adjacent
pairs) and an average planeꢀtoꢀplane distance is 3.39 Å. In fact, both
distances are shorter for FPtCzND than FPtOPhND. From single
crystal xꢀray analysis, the tighter and pair wise molecular packing
observed for FPtCzND probably manifest its EL spectra, which are
relatively narrow and the variation of EL wavelength is less dopant
concentration dependent (see the section of EL properties).
The UVꢀVisible absorption spectra of platinum complexes in
CH2Cl2 at 1 × 10ꢀ5 M are shown in Fig. 3. These platinum complexes
exhibit two types of absorption bands. The strong absorption band
below 300 nm is attributed to the πꢀπ* local transition (LC) of the
ligands. Except for FPtppND, each platinum complex shows
multiple and weaker absorption bands in a range of 300ꢀ475 nm,
which are assigned to some mixed electronic transitions of singlet
metalꢀtoꢀligand charge transfer (1MLCT) and triplet metalꢀtoꢀligand
charge transfer (3MLCT). Differently, the lowest energy (the longest
wavelength) one among the multiple absorption bands in the range
of 300ꢀ475 nm becomes much stronger in absorbance (Fig.3). This
strong absorption band can be ascribed to mixed electronic
1
transitions of MLCT and intraligand charge transfer (ILCT), which
is induced by the strong electronꢀdonating piperidino amine
substituent.16
FPtmmND
FPtOPhND
FPtppND
8.0x104
FPtCzND
6.0x104
4.0x104
2.0x104
0.0
250 300 350 400 450 500
Wavelength (nm)
Fig. 1 ORTEP diagram of FPtOPhND with thermal ellipsoids
shown at the 50% probability level (top). Stacking diagram (from
two viewing angles ~90o difference) with an emphasis on the almost
linear and exactly same PtꢀPt distance depicted with sky blue lines
(bottom). Selected bond lengths (Å): PtꢀN(1) = 2.022, PtꢀO(1) =
2.120, PtꢀN(17) = 1.990, PtꢀC(24) = 1.978. In the stacking diagram,
all hydrogen atoms are removed for clarity.
Fig. 3 UVꢀVis absorption spectra of FPtXND in CH2Cl2 at a
concentration of 1 × 10ꢀ5 M.
On the other hand, the absorption spectra of these platinum
complexes can be either redꢀshifted or blueꢀshifted relative to those
of the previously reported FPtmND or new FPtmmND reported
herein, depending on the electron donating nature of the substituent.
The strong electron donating ability of piperidino substituent shows
the largest blueꢀshifting on the absorption band with the longest
wavelength, whereas less stronger electron donating phenoxy
substituent exhibits the second largest blueꢀshifting. Different from
FPtOPhND and FPtppND, FPtCzND shows substantial redꢀshifted
instead of blueꢀshifted absorption spectrum, even though carbazolyl
moiety is an electron donating group. The twisted conformation of
CzND largely inhibit tangible πꢀconjugation between 1,5ꢀ
naphthyridine and carbazole moiety, and carbazole substituent of
FPtCzND becomes an electron acceptor due to the relatively higher
electron negativity of nitrogen atom. Single crystal xꢀray structure of
FPtCzND (Fig. 2) confirm the model of twisted conformation of
CzND.
Photoluminescence spectroscopic analysis
The emission spectra of platinum complexes in solution with varied
concentration are shown in Fig. 4 and Table 1. In a dilute solution of
CH2Cl2 at 2 × 10ꢀ5 M, FPtmmND, FPtOPhND and FPtppND
exhibit a greenishꢀyellow PL with λmaxPL at 550, 555 and 545 nm,
Fig. 2 ORTEP diagram of FPtCzND with thermal ellipsoids shown
at the 50% probability level (top). Stacking diagram (from two
viewing angles ~90o difference) with an emphasis on the two PtꢀPt
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Table 1 Photophysical data and thermal decomposition temperature of FPtXND.
λmaxPL [nm] in CH2Cl2
c
λmaxab (ε) [nm] in CH2Cl2
[104 Mꢀ1 cmꢀ1]
Td
a
b
Pt complexes
ΦPL
τp [ꢁs]
[oC]
2x10ꢀ5
550
M
2x10ꢀ4 M
2x10ꢀ3 M
593
415 (1.81)
572
0.09, 0.15
5.68
304
FPtmmND
409 (2.25)
407 (6.40)
437 (1.72)
555
545
573
575
545
573
591
578
579
0.21, 0.10
0.08, 0.15
0.15, 0.04
6.12
5.61
25.16
319
351
392
FPtOPhND
FPtppND
FPtCzND
a
PL quantum yields determined in degassed CH2Cl2 and 5 wt% in PS thin film.
b Room temperature PL lifetime determined in degassed CH2Cl2
c Thermal decomposition temperature (at 5% weight loss) determined by TGA under nitrogen atmosphere.
respectively, whereas FPtCzND displays an orange PL with λmaxPL at
1.2
-
In CH2Cl2 2 x10 5
M
FPtmmND
573 nm. At such diluted concentration, each of the platinum
complexes can be presumed in nonꢀaggregated form, i.e., monomer
instead of dimer, trimer, and higher aggregates. Except for
FPtOPhND, the emission wavelength shifting is in general parallel
to that of absorption wavelength. When the concentration of
platinum complex is increased, all emission spectra display a
consistent trend of redꢀshifting and broadening (Fig. 4 and Table 1),
which indicates the formation of aggregates showing variable
excimer emission in solution. Within the context, the observation of
excimer emission of FPtCzND takes place at higher concentration
than the other three platinum complexes, which is consistent with the
twisted (bulky) conformation of CzND that reduces the tendency of
molecular aggregation in average. Such aggregationꢀinhibited
conformation reduces the emission of aggregation, which usually has
a wavelength greater than 625 nm or so (see solid state PL spectra in
Fig. 6 later). Accordingly, under the same solution concentration,
FPtCzND has a weaker PL intensity at long wavelength region
around 625~700 nm because of less formation of aggregate/excimer
in solution. As the results, FPtCzND exhibits the second weakest PL
among FPtXND at wavelength beyond 625 nm (see Fig. 5 for the
normalized solution PL spectra under the same concentration).
FPtOPhND
FPtppND
FPtCzND
1.0
0.8
0.6
0.4
0.2
0.0
pp, OPh, mm, Cz
pp, Cz, OPh, mm
450 500 550 600 650 700 750
Wavelength (nm)
Fig. 5 Intensity normalized PL spectra of FPtmmND, FPtOPhND,
FPtppND, and FPtCzND in CH2Cl2 at 2 × 10ꢀ5 M.
In the solid state, emission or PL spectra of platinum complexes
display a variety of emission, depending on the concentration of
platinum complex or type of host material incorporating platinum
complex. Fig. 6 depicts the thin film PL spectra of FPtXND in
polystyrene (PS), CBP, or 4PꢀNPD as the host materials. For 5 wt%
of all FPtXND in CBP or PS hosted thin film, Fig. 6 show similar
emission to the corresponding PL of FPtXND (λmax 530~575 nm)
in diluted solution. However, in 4PꢀNPD hosted thin film, all
platinum complexes exhibit more redꢀshifted PL spectra with λmax
varied in a range of 575ꢀ650 nm. Moreover, even more redꢀshifted
PL spectra are observed (some of them have λmaxPL beyond 650 nm)
in 100 wt% FPtXND for all platinum complexes. Regardless which
host materials, the redꢀshifted emissions in thin film are attributed to
the aggregation of FPtXND, similar to many other platinum
complexes in the solid state. This observation is in good agreement
with the molecular packing of FPtOPhND and FPtCzND, of which
the average planeꢀtoꢀplane distance is 3.62 and 3.39 Å, respectively.
As a result, the close packing would facilitate the formation of dimer
or higher aggregates. This gives rise of the emission around 579ꢀ640
nm because of metalꢀmetalꢀtoꢀligand charge transfer transition
(MMLCT) .17
1.2
PL
λmax
PL
FPtmmND
1.2
1.0
0.8
0.6
0.4
0.2
0.0
FPtOPhND
λmax
2 x10 5 M 550 nm
2 x10 4 M 572 nm
-
1.0
0.8
0.6
0.4
0.2
0.0
-
2 x10 5
M
M
M
555 nm
575 nm
591 nm
PL
-
-
2 x10 4
2 x10 3
-
593 nm
M
-
2 x10 3
PL
450 500 550 600 650 700 750 800 850
Wavelength (nm)
450 500 550 600 650 700 750 800 850
Wavelength (nm)
1.2
1.0
0.8
0.6
0.4
0.2
0.0
1.2
1.0
0.8
0.6
0.4
0.2
0.0
PL
PL
FPtppND
FPtCzND
λmax
λmax
2 x10 5 M 545 nm
-
2 x10-5 M
573 nm
-
2 x10 4
M
M
-4
545 nm
573 nm
M
2 x10-3 M 579 nm
2 x10
-
2 x10 3
578 nm
450 500 550 600 650 700 750 800 850
Wavelength (nm)
450 500 550 600 650 700 750 800 850
Wavelength (nm)
5 wt% in PS
5 wt% in CBP
10 wt% in 4P-NPD
100 wt%
5 wt% in PS
5 wt% in CBP
10 wt% in 4P-NPD
100 wt%
1.0
0.8
0.6
0.4
0.2
0.0
1.0
0.8
0.6
0.4
0.2
0.0
FPtmmND
Fig. 4 Normalized emission spectra of FPtmmND, FPtOPhND,
FPtppND, and FPtCzND in CH2Cl2 with varied concentrations.
FPtOPhND
500 550 600 650 700 750 800 850
Wavelength (nm)
500 550 600 650 700 750 800 850
Wavelength (nm)
4 | J. Name., 2012, 00, 1-3
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DOI: 10.1039/C4TC01791A
5 wt% in PS
5 wt% in CBP
10 wt% in 4P-NPD
100 wt%
platinum complex based on 8ꢀsubstitutedꢀ1,5ꢀnaphthyridinolate
(XND) and 2ꢀ(2,4ꢀdifluorophenyl)pyridine (F) ligands. The
5 wt% in PS
5 wt% in CBP
10 wt% in 4P-NPD
100 wt%
1.0
0.8
0.6
0.4
0.2
0.0
1.0
0.8
0.6
0.4
0.2
0.0
previously known FPtmND (or FPtmmND in the present study)
exhibits the HOMO electron density mostly on the phenoxide,
difluorophenyl moiety, and platinum metal ion. The LUMO electron
density has a sizable contribution from methylpyridine part of mND
(or mmND) and pyridine ring of F ligand (Fig. 8). For FPtOPhND,
moderate electron donating phenoxy substituent affords similar
contour of HOMO/LUMO to those of FPtmND (or FPtmmND).
For FPtppND, strong electron donating piperidine substituent
significantly alters the contour of HOMO by shifting electron
density to piperidinopyridine ring and diminishing the electron
density on difluorophenyl moiety, whereas the contour of LUMO
remains similar to that of FPtmmND. Such computational results of
FPtppND suggest that the lowest energy electronic transition by
photoexcitation has some characteristics of ligandꢀtoꢀligand charge
transfer (LLCT), which has a stronger absorption intensity than that
FPtppND
FPtCzND
500 550 600 650 700 750 800 850
Wavelength (nm)
500 550 600 650 700 750 800 850
Wavelength (nm)
Fig. 6 Normalized PL spectra (excitation wavelength was 380 nm
except for 100 wt% FPtmmND and FPtOPhND which were 420
nm) of the thin film of FPtmmND, FPtOPhND, FPtppND and
FPtCzND (100 wt%) and 5 wt% FPtXND thin film in PS, CBP and
4PꢀNPD.
The PL quantum yields (ΦPL) of FPtXND were measured in
degassed dilute solution of CH2Cl2 by the optical dilute method with
[Ru(bpy)3](PF6)2] in acetonitrile (ΦPL = 0.062) as the reference. The
platinum complexes show ΦPL of 0.09, 0.21, 0.08 and 0.15 for
FPtmmND, FPtOPhND, FPtppND, and FPtCzND, respectively
(Table 1). We note that ΦPL of FPtOPhND is particularly higher
than the rest FPtXND and it provides FPtOPhND a justified reason
for high efficiency OLED, either monochromatic or hybrid white EL.
In addition, the emission lifetimes (τ) were recorded for FPtXND
complexes in degassed CH2Cl2 as well (see Fig. 7 for solution PL
decay profile).
1
3
of MLCT or MLCT. For FPtCzND, carbazolyl substituent also
alters the contour of HOMO but different from that of FPtppND.
Significant electron density was found on carbazolyl substituent
according to our computation (Fig. 8). Moreover, based on the
contour of HOMO and LUMO of FPtCzND, we can infer that the
lowest energy photoexcitation involves a significant reduction of
electron density on carbazolyl substituent and an increasing electron
density on pyridine ring of both ND and F ligands. Such
computational results are consistent with the PET proposed for
FPtCzND in photoluminescence spectroscopic analysis shown
above.
100
FPtmmND
FPtOPhND
FPtppND
FPtCzND
10
1
0
40
80
Time (
120 160 200
s)
ꢀ
Fig. 7 Solution PL decay profile of FPtXND.
The platinum complexes have the emission lifetime of 5.68,
6.12, 5.61 and 25.16 ꢁs, respectively (Table 1). All platinum
complexes showed the emission lifetime in the microsecond range,
suggesting that the emission originates from the 3MLCT state.
However, FPtCzND has much longer τ than other FPtXNDs. Based
on the transient spectroscopic study of indoleꢀsubstituted zinc
phthalocyanine, a longꢀlived charge separated state due to the
photoinduced electron transfer (PET) from indole to zinc
phthalocyanine was observed.18 We infer that the long τ measured
for FPtCzND can be attributed to the twisted conformation of CzND,
which shares the common structural feature of indole substiuent that
facilates PET process generating longꢀlived charge separated state
and long τ. Such inference is also supported by the HOMO
computational study and electrochemical oxidation potential
determination shown below.
Computational study
Quantum chemical calculations used DFT with the hybrid B3LYP
functional and 6ꢀ31G* basis set to gain insight on the variation of
HOMO/LUMO electron density distribution due to the different
substituent of FPtXND (Fig. 8). The frontier molecular orbitals of
Alq3 have been described previously19 and it is known that the
HOMO orbitals have significant electron density on the phenoxide
side of the ligand, whereas pyridine ring makes significant
contribution to the LUMO orbitals. For FPtXND, it is a heteroleptic
Fig. 8 Calculated electron density contour plots of HOMO (left) and
LUMO (right) of the platinum complexes.
This journal is © The Royal Society of Chemistry 2012
J. Name., 2012, 00, 1-3 | 5

Journal of Materials Chemistry C
Page 6 of 14
View Article Online
ARTICLE
Journal Name
DOI: 10.1039/C4TC01791A
Electrochemical properties
The electrochemical properties of the platinum complexes were
recorded in CH2Cl2 by cyclic voltammetry (CV) (see Fig. 9). Table 2
summarizes CV data obtained in this study. The energy level of
HOMO of each platinum complex was determined from the first
electrochemical oxidation potential (vs. saturated Ag/AgNO3).
However, due to the illꢀprofile of the first oxidation potential, we
took the relative peak position of anodic current of ferrocene and
FPtXND cyclic voltammograms in the calculation of HOMO energy
level (Fig. 9).
Fig. 10 Energy level alignment of materials involved in OLEDs.
6.0x10-6
4.0x10-6
3.0x10-6
2.0x10-6
Ferrocene
FPtOPhND
Ferrocene
FPtmmND
Thermal properties
4.0x10-6
*
*
The thermal stabilities of platinum complexes were examined by
using thermogravimetric analysis (TGA) under nitrogen atmosphere
*
2.0x10-6
0.0
*
1.0x10-6
o
with a heating rate of 20 C minꢀ1. Fig. 11 and Table 1 show TGA
0.0
-1.0x10-6
-2.0x10-6
data of platinum complexes. FPtmmND, FPtOPhND, FPtppND
and FPtCzND are thermally stable with the decomposition
temperature at 304, 319, 351 and 392 oC, respectively. These results
indicate that all platinum complexes in these series are suitable for
the use in OLED fabrication by vacuumꢀthermalꢀdeposition process.
-2.0x10-6
-1.0 -0.5 0.0 0.5 1.0 1.5 2.0
Potential (V)
-1.0 -0.5 0.0 0.5 1.0 1.5 2.0
Potential (V)
4.0x10-6
3.0x10-6
2.0x10-6
1.2x10-6
9.0x10-7
6.0x10-7
Ferrocene
FPtppND
Ferrocene
FPtCzND
*
*
*
*
100
3.0x10-7
1.0x10-6
0.0
FPtmmND
FPtOPhND
90
0.0
-3.0x10-7
-6.0x10-7
FPtppND
FPtCzND
80
70
60
50
40
30
-1.0x10-6
-2.0x10-6
-1.0 -0.5 0.0 0.5 1.0 1.5 2.0
Potential (V)
-1.0 -0.5 0.0 0.5 1.0 1.5 2.0
Potential (V)
Fig. 9 Cyclic voltammograms of FPtmmND, FPtOPhND,
FPtppND, FPtCzND and ferrocene (reference).
200
400
600
800
1000
Table 2 Electrochemical data of FPtXND.
Temperature (oC)
Fig. 11 Thermogravicmetric analysis (TGA) data for platinum
complexes.
Pt
Eoxd,1
(V)
1.00
0.96
0.91
1.05
0.60
EHOMO
(eV)
5.20
5.16
5.11
5.25
ꢀ
λonset
(nm)a
445
438
435
473
ꢀ
Eg
(eV)b
2.79
2.83
2.85
2.62
ꢀ
ELUMO
(eV)b
2.41
2.33
2.26
2.63
ꢀ
Complexes
FPtmmND
FPtOPhND
FPtppND
FPtCzND
ferrocene
Electroluminescence properties
Monochromatic OLEDs
To evaluate the EL properties of FPtmmND, FPtOPhND,
FPtppND and FPtCzND as potential emitters for monochromatic
OLEDs, two types of device structures (Device A and B) were
a Determined from the onset absorption spectrum. b Estimated from the onset
absorption spectrum by equation of Eg = 1240/ꢀonset. c Deduced from the
HOMO and Eg.
fabricated
by
vacuumꢀthermalꢀdeposition
process
with
configurations of ITO/NPB or 4PꢀNPD (40nm)/4,4'ꢀN,N′ꢀ
dicarbazolebiphenyl (CBP): x% FPtXND (20 nm)/TPBI (40
nm)/LiF(1 nm)/Al (150 nm) as shown in Fig. 12, where NPB and
4PꢀNPD were used as holeꢀtransporting layer (HTL) in Device A
and B, respectively. CBP was used as host material for single
emitting layer (EML) and TPBI was used as electronꢀtransporting
layer (ETL). To optimize the EL performances, the dopant
concentration of FPtXND was varied from 2 to 5 and 8 wt%.
From the experimental results, the ease of oxidation are quite
consistent with the intuition based on chemical structure of these
platinum complexes. Consistent with electron donating trend of the
substituent, the oxidation potential increases following order of
FPtmmND > FPtOPhND > FPtppND. Unusually, FPtCzND has
the highest oxidation potential among the series. This is not
unreasonable because the carbazolyl substituent is electron
withdrawing instead of electron donating, which is deduced from the
crystal structure xꢀray analysis (carbazolyl substituent has a nonꢀπꢀ
conjugated twisted conformation to 1,5ꢀnapthyridinolate ring) and
absorption/emission spectroscopy analysis in the present study. With
optical energy gap (Eg) obtained from the absorption spectroscopy,
HOMO and LUMO energy levels of other materials including 4,4'ꢀ
bis[Nꢀ(1ꢀnaphthyl)ꢀNꢀphenylamino]ꢀbiphenyl (NPB), 4PꢀNPD, CBP,
and 1,3,5ꢀtris(Nꢀphenylbenzimidazoleꢀ2ꢀyl)benzene (TPBI) were
estimated by the same method and they are illustrated in Fig. 10.11
6 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 2012

Page 7 of 14
Journal Name
Journal of Materials Chemistry C
View ArticAle ROnTliInCeLE
DOI: 10.1039/C4TC01791A
Device B
10
100
10
Fig. 12 The device configurations and the molecular structures of the
relevant compounds used in these devices.
1
FPtmmND 5 wt%
FPtOPhND 5 wt%
FPtppND 8 wt%
FPtCzND 5 wt%
1
Some of the EL spectra and EL efficiency data of Device A and B
are plotted in Fig. 13 and 14. More extensive monochromatic device
data can be found in Fig. S2, S3 and S4. Containing FPtmmND,
FPtOPhND, or FPtppND in all dopant concentration, Device A and
B exhibited greenish yellow EL (λmaxEL around 544~562 nm), which
are similar to the individual PL in diluted solution (Fig. 4).
Although monochromatic EL spectrum got broadening with
increasing dopant concentration, both Device A and B having
FPtmmND or FPtOPhND dopant displayed the optimum EL
efficiency at 5 wt% dopant concentration, whereas the peak EL
efficiency of Device A and B with FPtppND dopant were obtained
at 8 wt% dopant concentration.
1
10
100
1000
10000
Electroluminance (cd/m2)
Fig. 14 External quantum efficiency and power efficiency as a
function of electroluminance of monochromatic Device A (top) and
Device B (bottom) at 5 wt% or 8 wt% of FPtXND.
Table 3 summarizes the optimized device performances using
different platinum complexes as dopant materials (Device A1ꢀ4 and
Device B1ꢀ4). The most efficient greenish yellow EL with CIEx,y
(0.42ꢀ0.43, 0.57) were achieved from Device A2 and B2 having
FPtOPhND dopant, which exhibited EL efficiencies of 12.4%, 44.8
cd Aꢀ1, 33.3 lm Wꢀ1 and 15.0%, 59.3 cd Aꢀ1, 36.7 lm Wꢀ1,
respectively. We attribute the high EL efficiency of Device A2 and
B2 to the high ΦPL 21% of FPtOPhND, which is the highest among
four platinum complexes studied herein. When employing FPtCzND
as dopant, orange yellow EL with CIEx,y (0.49ꢀ0.51, 0.47) was
obtained for Device A4 and B4. Basically, such EL from FPtCzND
OLEDs is more efficient than the greenish yellow EL of FPtmmND
or FPtppND OLEDs (Table 3). In addition, having 4PꢀNPD as HTL,
we found that Device B exhibited superior performance to those of
Device A due to its higher hole mobility (ꢁh = 6.6 × 10ꢀ4 cm2 Vꢀ1 sꢀ1)
as compared to conventional NPB (ꢁh = 3.2 × 10ꢀ4 cm2 Vꢀ1 sꢀ1).20
Device A
1.0
0.8
5 wt% FPtmmND
5 wt% FPtOPhND
5 wt% FPtppND
0.6
5 wt% FPtCzND
0.4
0.2
0.0
400
500
600
700
800
Wavelength (nm)
Hybrid white OLEDs
Device B
1.0
0.8
0.6
0.4
0.2
0.0
Single EML devices (Device C and D)
Hybrid white OLEDs were first fabricated with a relatively simple
configuration of Device C or Device D, ITO/NPB or 4PꢀNPD (40
nm)/4PꢀNPD: x% FPtXND (20 nm)/TPBI (40 nm)/LiF(1 nm)/Al
(150 nm) as shown in Fig. 12. In these devices, 4PꢀNPD was used as
the host material for platinum complex dopant in single EMLꢀtype
device. To realise an appropriate dopant concentration for WOLED
devices, the dopant concentration of each platinum complex in 4Pꢀ
NPD host was varied with three different concentrations of 2, 5 and
8 wt%. Fig. 15 shows the white EL spectra of Device C and D
containing FPtmmND, FPtOPhND, FPtppND, or FPtCzND as
dopants. More EL profiles and device performances are
demonstrated in Fig. S5, S6 and S7.
5 wt% FPtmmND
5 wt% FPtOPhND
5 wt% FPtppND
5 wt% FPtCzND
400
500
600
700
800
Wavelength (nm)
Fig. 13 Normalized EL spectra of Device A and B with different
platinum complexes at 5 wt%.
Device C
Device A
1.0
C1, 8 wt% FPtmmND
(0.39, 0.30), CRI 80
10
0.8
0.6
0.4
0.2
0.0
C2, 8 wt% FPtOPhND
(0.42, 0.34), CRI 79
C3, 8 wt% FPtppND
(0.34, 0.31), CRI 84
C4, 5 wt% FPtCzND
(0.37, 0.28), CRI 67
100
10
1
FPtmmND 5 wt%
FPtOPhND 5 wt%
FPtppND 8 wt%
FPtCzND 5 wt%
1
400 500 600 700 800 900
Wavelength (nm)
1
10
100
1000 10000
Electroluminance (cd/m2)
This journal is © The Royal Society of Chemistry 2012
J. Name., 2012, 00, 1-3 | 7

Journal of Materials Chemistry C
Page 8 of 14
VJieowuArrtnicalelONnlainme e
ARTICLE
DOI: 10.1039/C4TC01791A
Wꢀ1. In fact, hybrid white OLED containing 2 wt% FPtCzND
dopant (Device D4ꢀ2 in Table 3) are the second best device,
although it has significantly lower CRI of 62 due to the narrow
yellowꢀorangeꢀred emission band of FPtCzND excimer/aggregate.
By increasing dopant concentration (see Device D4ꢀ5 and D4ꢀ8 in
Table 3), the EL efficiency of FPtCzND OLED can be significantly
improved as high as 10.4%, 24.4 cd Aꢀ1, or 11.8 lm Wꢀ1, surpassing
that of 8 wt% FPtOPhND dopant device (Device D2ꢀ8). However,
Device D4ꢀ5 or D4ꢀ8 is no longer a white OLED. It showed EL with
CIEx,y (0.45ꢀ0.57, 0.34ꢀ0.41), a yellowish white or yellow orange
colour. Finally, through the variation of dopant concentration in the
fabrication of FPtOPhND and FPtCzND OLEDs (Device D2ꢀ2,5,8
and Device D4ꢀ2,5,8 in Table 3), we have clearly seen the different
magnitude of wavelength shifting of yellowꢀorangeꢀred emission
band. From 2 to 8 wt% changes of dopant concentration, there is a
30 nm redꢀshifting of EL due to the excimer/aggregate of
FPtOPhND. There is only 7 nm redꢀshifting for FPtCzND devices.
Such observation is very much in accordant with the different
molecular packing found by xꢀray crystallography. Molecules of
FPtCzND form pair wise stacking in solid state and the number of
stacking molecule is pretty much fixed at two. Whereas molecules of
FPtOPhND form column like long stack, the number of molecule in
a column stack is variable and up to dopant concentration in the thin
film of the device. Nearly pure white EL CIEx,y (0.34, 0.31) was also
achieved from FPtppND dopant (8 wt%) in Device C3 and D3.
Both devices exhibited relatively high CRI of 84~85, which is the
highest among Device C and D. It is mainly due to the additional
greenish yellow emission of monomeric FPtppND, partially filling
the spectroscopic gap between the blue emission of 4PꢀNPD and the
yellowꢀorangeꢀred emission of FPtppND excimer/aggregate.
However, the maximum EL efficiencies of Device C3 and D3 are
low (4.3%, 8.5 cd Aꢀ1, and 4.1 lm Wꢀ1) because of the low ΦPL 8% of
FPtppND.
Device D
1.0
0.8
0.6
0.4
0.2
0.0
D1, 5 wt% FPtmmND
(0.34, 0.26), CRI 79
D2-8, 8 wt% FPtOPhND
(0.36, 0.28), CRI 81
D3, 8 wt% FPtppND
(0.34, 0.31), CRI 85
D4-2, 2 wt% FPtCzND
(0.33, 0.25), CRI 62
400 500 600 700 800 900
Wavelength (nm)
Fig. 15 Normalized hybrid white EL spectra of single EML device
(Device C and D) with varied FPtXND dopant concentration.
Regardless of HTL, either NPB or 4PꢀNPD, Device C and D
exhibited very different EL profiles from those of Device A and B,
which are hosted by CBP. Two strong emissions were observed,
EL
containing (i) a blue emission with λmax around 430~460 nm (ii) a
broad band yellowꢀorangeꢀred emission with λmaxEL around 585~610
nm. These two different emission bands can be attributed to the deep
blue fluorescence from 4PꢀNPD host (and maybe HTL) and
excimer/aggregate emission from platinum complex. Hybrid white
EL with CIEx,y (0.34ꢀ0.39, 0.26ꢀ0.30) from FPtmmND OLEDs was
achieved with 8 wt% dopant concentration. Device C1 and D1
displayed the peak EL efficiencies of 4.0%, 7.2 cd Aꢀ1, 2.6 lm Wꢀ1
and 3.4%, 5.7 cd Aꢀ1, 2.1 lm Wꢀ1, and CRI of 80 and 79, respectively.
This is nearly the only case among four platinum complexes
showing better EL efficiency with NPB than 4PꢀNPD HTL.
Considering the efficiency of white EL, FPtmmND has the worst
performance. Once again, the best performance hybrid white EL was
achieved with 8 wt% FPtOPhND dopant (Device D2ꢀ8 in Table 3),
showing maximum EL efficiencies of 7.4%, 13 cd Aꢀ1, and 6.7 lm
Table 3 Device performances with different doping concentrations.
Dopant
Conc.
(wt%)
EL
λmax
Von
EQE
(%)b
CE
PE
L,Voltage
CIE
Device
Dopant
CRIe
(nm)
(V)a
(cd Aꢀ1)b
(lm Wꢀ1)b
(cd mꢀ2) (V)c
(x,y)d
A1
B1
A2
B2
A3
B3
A4
B4
C1
D1
C2
D2ꢀ2
D2ꢀ5
D2ꢀ8
C3
5
5
5
5
8
8
5
5
8
8
8
2
5
8
8
8
5
2
5
8
543
544
551
551
549
551
574
576
453,614
453,604
468,608
447,572
452,596
452,602
450,589
453,581
447,586
445,582
449,583
449,589
4.5
4.5
4.0
4.0
5.0
4.5
3.5
4.0
5.0
4.5
5.0
4.0
4.0
4.0
3.5
4.0
4.5
5.0
5.0
4.0
4.0
4.0
6.6(6.7)
7.1(7.6)
10.8(12.4) 43.7(44.8)
14.9(15.0) 58.6(59.3)
6.7(7.2)
7.3(7.4)
8.7(8.8)
27.4(27.8)
30.1(32.0)
11.8(13.2)
13.4(18.3)
22.5(33.3)
33.1(36.7)
9.9(12.0)
10.0(12.9)
15.0(15.1)
13.0(17.1)
2.4(2.6)
1.9(2.1)
3.7(4.7)
0.9(1.9)
4.7(5.1)
6.6(6.7)
3.3(3.4)
3.1(3.8)
4.4(5.1)
3.7(3.8)
5.7(6.8)
7.9(11.8)
9.9(11.6)
6.8(6.8)
12816(15)
16863(15)
25448(15)
19386(13)
10337(15)
9232(15)
7886(15)
7355(15)
5098(15)
5273(15)
7929(15)
2474(15)
8596(15)
11762(15)
4875(14.5)
4413(15)
4965(15)
3367(15)
5196(15)
5070(15)
10523(15)
7993(15)
(0.39,0.60)
(0.39,0.60)
(0.42,0.57)
(0.43,0.57)
(0.40,0.57)
(0.38,0.57)
(0.51,0.47)
(0.49,0.47)
(0.39,0.30)
(0.34,0.26)
(0.42,0.34)
(0.19,0.15)
(0.34,0.28)
(0.36,0.28)
(0.34,0.31)
(0.34,0.31)
(0.37,0.28)
(0.33,0.25)
(0.45,0.34)
(0.57,0.41)
(0.37,0.38)
(0.33,0.31)
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
ꢀ
80
79
79
ꢀ
80
81
84
85
67
62
ꢀ
FPtmmND
FPtmmND
FPtOPhND
FPtOPhND
FPtppND
27.3(28.7)
29.5(29.8)
28.3(28.6)
FPtppND
FPtCzND
FPtCzND
FPtmmND
FPtmmND
FPtOPhND
FPtOPhND
FPtOPhND
FPtOPhND
FPtppND
9.8 (10.5) 31.0(33.5)
3.9(4.0)
3.0(3.4)
5.6(6.0)
2.2(3.0)
5.9(6.0)
7.1(7.4)
3.3(3.3)
3.7(4.2)
5.3(5.7)
6.4(6.7)
7.5(8.1)
7.1(7.2)
5.0(5.7)
10.0(10.5)
2.7(3.6)
10.4(10.5)
12.1(13.0)
6.7(6.7)
D3
C4
7.7(8.5)
FPtppND
10.1(11.0)
11.7(12.3)
17.3(18.7)
FPtCzND
FPtCzND
FPtCzND
FPtCzND
FPtOPhND
FPtOPhND
D4ꢀ2
D4ꢀ5
D4ꢀ8
W1
W2
9.0(10.4) 20.4(23.1)
11.6(11.8) 25.5(25.9)
10.6(10.6) 18.4(18.4)
ꢀ
87
91
5 & 8 441,556~560
5 & 8 436,560,605
a Turnꢀon voltage is the one at which the luminance over 1 cd mꢀ2 was obtained. b The data for external quantum efficiency (EQE), current efficiency (CE), and
power efficiency (PE) obtained at 500 cd/m2. The data of peak efficiency is listed in parentheses of efficiency data. cMaxmium electroluminance and driving
voltage. dCommission Internationale d'Eclairage chromaticity coordinates at 7~9 V; e Colour rendering index at 7~9 V.
8 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 2012

Page 9 of 14
Journal Name
Journal of Materials Chemistry C
View Article Online
ARTICLE
DOI: 10.1039/C4TC01791A
Double EML devices (Device W1 and W2)
100
10
1
To improve the EL efficiency, CRI, and colour purity (CIEx,y),
devices with double EML were further fabricated, in which the
platinum complex was doped into both CBP and 4PꢀNPD,
respectively, in twoꢀlayer structure. FPtOPhND was selected for
evaluation of WOLED performance due to its superior PL quantum
yield in solution and EL efficiency in Device A, B, C, and D. Device
W1 or W2 with configuration of ITO/NPB or 4PꢀNPD (40
nm)/CBP: 5% FPtOPhND (20 nm)/4PꢀNPD: 8% FPtOPhND (20
nm)/TPBI (40 nm)/LiF(1 nm)/Al (150 nm) was constructed.
According to the results of monochromatic devices and WOLEDs
with single EML structure, the dopant concentration of FPtOPhND
was crucial to realise pure white OLED. The optimized dopant
concentrations of FPtOPhND in CBP and 4PꢀNPD host were
controlled at 5 and 8 wt%, respectively. The EL spectra of Device
W1 and W2 are shown in Fig. 16, while their electroluminance
dependent EL efficiencies are depicted in Fig. 16 and corresponding
data are summarized in Table 3.
10
1
Device W1
Device W2
0.1
0.1
1000 10000
1
10
100
Electroluminance (cd/m2)
10000
1000
100
150
Device W1
Device W2
120
90
60
30
0
Device W1
7V (0.37, 0.38) CRI 87
8V (0.37, 0.39) CRI 88
9V (0.36, 0.38) CRI 89
10V(0.36, 0.37) CRI 90
8 wt% Device C2
1.0
0.8
0.6
0.4
0.2
0.0
5 wt% Device A2
0
2
4
6
8
10 12 14 16
Excimer
Monomer
4P-NPD
Voltage (V)
Fig. 17 External quantum efficiency and power efficiency as a
function of electroluminance (top) and electroluminanceꢀvoltageꢀ
current density curves (bottom) of Device W1 and W2.
400
500
600
700
800
900
Wavelength (nm)
Nearly perfect white EL was acquired for both Device W1 and W2.
With the contribution of greenish yellow EL from doped CBP layer,
the yellowꢀorangeꢀred emission band is much more broadened than
before in single EML device. Since greenish yellow emission is from
the isolated FPtOPhND, which is more EL efficient than that of
excimer/aggregate, CRI, CIEx,y and EL efficiency are improved
comprehensively. Device W1 exhibited maximum EL efficiency of
11.8%, 25.9 cd Aꢀ1, and 11.6 lm Wꢀ1 (Fig. 17); higher CRI of 87ꢀ90
and white colour purity as CIEx,y (0.37, 0.38). Moreover, the EL
spectra of this device were nearly same at different voltages of 7ꢀ10
V (see Fig. 16), which is due to the consistent exciton formation
distributed in CBP and 4PꢀNPD EMLs. For Device W2, it showed
even better CRI (91) and white colour purity as CIEx,y (0.33, 0.31) at
7 V. This is mainly due to the much increase of blue fluorescence
and moderate increase of greenish yellow phosphorescence in EL
spectra. Moreover, similar to Device W1, Device W2 exhibited
consistent white EL spectroscopic profile, which is essentially
voltage independent. However, due to the less efficiency nature of
fluorescenceꢀbased EL, somewhat lower peak EL efficiency of
10.6%, 18.4 cd Aꢀ1, or 6.8 lm Wꢀ1 was obtained by Device W2.
Nevertheless, double EML and single phosphorescence dopant
devices, Device W1 and W2, exhibit high CRI~90 and much better
EL efficiency and colour stability, when compared with those hybrid
white OLED based on platinum complexes reported in literature.9,10
Device W2
7V (0.33, 0.31) CRI 91
8V (0.33, 0.31) CRI 90
9V (0.33, 0.30) CRI 89
10V (0.33, 0.30) CRI 89
8 wt% Device D2
1.0
0.8
0.6
0.4
0.2
0.0
5 wt% Device B2
4P-NPD Monomer Excimer
400
500
600
700
800
900
Wavelength (nm)
Fig. 16 Normalized hybrid white EL spectra (top and center) of
double EML typeꢀdevice of Device W1 and W2 at 7ꢀ10V and their
CIE chromaticity diagram at 7V (bottom). The dash curves depicted
in the figure are adapted from the EL spectra of Device C2, A2, D2,
and B2 with the adjustment of EL intensity.
Conclusions
In summary, four new functionalized platinum complexes with
dimethyl, phenoxy, piperidino or carbazol substituent on 4ꢀhydroxyꢀ
1,5ꢀnaphthyridine were synthesized and fully characterized. Their
PL revealed that, in addition to greenish yellow or orange yellow
emission in diluted solution, the platinum complexes also exhibited
an excimer/aggregate emission (redꢀshifted wavelength) in
a
This journal is © The Royal Society of Chemistry 2012
J. Name., 2012, 00, 1-3 | 9

Journal of Materials Chemistry C
Page 10 of 14
ARTICLE
VJieowuArrtnicalelONnlainme e
DOI: 10.1039/C4TC01791A
concentrated solution or in thin film. PHOLEDs were constructed
Redox potentials of the compounds were determined by cyclic
based on these platinum complexes. By employing CBP as host, the voltammetry (CV) using a BAS 100B electrochemical analyzer with
monochromatic greenish yellow or orange yellow EL were obtained a scanning rate at 100 mV/s. The interested compounds were
with the maximum efficiencies of 15.0%, 59.3 cd Aꢀ1, 36.7 lm Wꢀ1 dissolved in deoxygenated dry CH2Cl2 with 0.1
M
for FPtOPhND and 10.5%, 33.5 cd Aꢀ1, 17.1 lm Wꢀ1 for FPtCzND, tetrabutylammonium perchlorate as the electrolyte. We used a
respectively. Upon switching the host material to 4PꢀNPD, platinum working electrode and a saturated nonaqueous Ag/AgNO3
fluorescenceꢀphosphorescence hybrid white OLEDs with a single referenced electrode. Ferrocene was used for potential calibration
emitting layer were achieved. Whereas FPtppND provided the (all reported potentials are referenced against Ag/Ag+) and for
highest CRI of 84~85, It was FPtOPhND showing highest white EL reversibility criteria. Energy level of ferrocene (4.8 V below the
efficiency, external quantum efficiency of 7.4%, current efficiency vacuum level) is used as the reference.24 The HOMO energy levels
of 13.0 cd Aꢀ1, or power efficiency of 6.7 lm Wꢀ1. They are even were calculated with empirical relation EHOMO = ꢀe[(Eoxd,1
better than those of FPtmND reported previously.11 With a double E(ferrocene)) + 4.8] eV.
emitting layer design of hybrid white OLED, the performance of
ꢀ
X-Ray Crystallography Studies
FPtOPhND OLED has been improved comprehensively. Nearly
perfect white EL having CIEx,y (0.33, 0.31) was achieved with high
efficiency (10.6%, 18.4 cd Aꢀ1, and 6.8 lm Wꢀ1) and very high CRI of
91. Moreover, such white EL has little changes on both CRI and
CIEx,y when the driving voltage varied between 7 and 10 V. These
results clearly demonstrate the great potential of hybrid white OLED
having double emitting layer design together with blue fluorescent
host and dual phosphorescence from single platinum complex dopant
for display and lighting applications.
Data collection was carried out on a Brucker X8APEX CCD
diffractometer at 100 K for FPtOPhND and FPtCzND single
crystals. The radiation of Mo radiation (λ = 0.71073 Å) was used
for both crystals. The unit cell parameters were obtained by a leastꢀ
square fit to the automatically centered settings for reflections.
Intensity data were collected by using the
ω/2θ scan mode.
Corrections were made for Lorentz and polarization effects. The
structures were solved by direct methods SHELXꢀ97.25 All nonꢀ
hydrogen atoms were located from the difference Fourier maps and
were refined by fullꢀmatrix leastꢀsquares procedures. The position
of hydrogen atoms was calculated and located. Calculations and fullꢀ
matrix leastꢀsquares refinements were performed utilizing the
WINGX program package26 in the evaluation of values of R (Fo) for
reflections with I > 2σ(I) and Rw (Fo), where R = Σ||Fo| ꢀ |Fc||/Σ|Fo|
Experimental Section
General information
Photoluminescence (PL) spectra were recorded on a Hitachi
fluorescence spectrophotometer Fꢀ4500, and the same
spectrophotometer was used to record the EL spectra of OLEDs.
UVꢀvisible electronic absorption spectra were recorded on a
2
2 2
and Rw = [Σ{w(Fo ꢀ Fc2)2}/Σ{w(Fo ) }]1/2
.
Intensities were
corrected for absorption.
1
HewlettꢀPackard 8453 Diode Array spectrophotometer. The H and
13C NMR spectra were recorded on a Bruker AMXꢀ400 MHz, AVAꢀ
400 MHz or Bruker AVꢀ500 MHz Fourierꢀtransform spectrometer at
room temperature. Elemental analyses (on a PerkinꢀElmer 2400
CHN Elemental Analyzer) and electrospray ionization (ESI) or
matrixꢀassisted laser desorption/ionization timeꢀofꢀflight (MALDIꢀ
TOF) mass spectra (on a VA Analytical 11ꢀ250J or 4800 MALDI
TOF/TOF Analyzer) were recorded by the Elemental Analyses and
Mass Spectroscopic Laboratory inꢀhouse service of the Institute of
Chemistry, Academic Sinica. Thermogravimetric analyse was
performed under nitrogen with a PerkinꢀElmer TGAꢀ7 TG analyzer.
Luminescence lifetime was determined on an Edinburgh FL920
timeꢀcorrelated pulsed singleꢀphotonꢀcounting instrument. The
phosphorescence emission was detected at 90o via a second Czernyꢀ
Turner design monochromator onto a thermoelectrically cooled redꢀ
sensitive photomultiplier tube. The resulting photon counts were
stored on a microprocessorꢀbased multichannel analyzer. The
instrument response function was profiled using a scatter solution
and subsequently deconvoluted from the emission data to yield an
undisturbed decay. Nonlinear least squares fitting of the PL decay
curves were performed with the LevenburgꢀMarquardt algorithm and
implemented by the Edinburgh Instruments F900 software.
OLED device fabrication and measurements
OLED devices were fabricated by thermal vacuum deposition. The
substrate was an indiumꢀtinꢀoxide (ITO) coated glass (Merck
Display Technology, Taiwan) with a sheet resistance of < 30 ꢂ/sq.
ITOꢀcoated glass substrates were cleaned with detergent, deionized
water, acetone, and isopropanol, followed by oxygen plasma
treatment. The current density–voltage–luminance characteristics of
the devices were measured using a Keithley 2400 source meter and a
Newport 1835C optical meter equipped with a Newport 818ꢀST
silicon photodiode, respectively. The device was placed close to the
photodiode such that all the forward light entered the photodiode.
The effective size of the emitting diodes was 4.00 mm2, which is
significantly smaller than the active area of the photodiode detector,
a condition known as “underꢀfillling”, satisfying the measurement
protocol.27 This is one of the most conventional ways in measuring
the EL efficiency of OLEDs, although sometimes experimental
errors may arise due to the nonꢀLambertian emission of OLEDs. The
colour rendering index (CRI) of white OLEDs was measured by a
spectroradiometer (Specbos 1201, JETI Technishe Instrumente
GmbH).
Materials
Emission quantum yields (ΦPL) in degassed CH2Cl2 were
=
2,2’ꢀbipyridine) in
For the materials used in device fabrication, NPB,28 CBP,29 TPBI,30
2ꢀ(2,4ꢀdifluorophenyl)pyridine (F)31 and 4PꢀNPD11 were prepared
via published methods. All materials were purified by vacuum train
sublimation before the usage in device fabrication. Synthetic
precursors 1 and 2, 3ꢀnitropyridine derivatives (3OPh, 3pp, and 3Cz),
and 3ꢀpyridiylamine derivatives (4OPh, 4pp, and 4Cz) were prepared
by adopting the synthetic protocols reported in literatures with slight
modification as shown in ESI. The Pt ꢁꢀdichloroꢀbridged dimer
(FPtCl)2 was prepared following literature procedures.32 All
reactions were performed under nitrogen. Solvents were carefully
dried and distilled from appropriate drying agents prior to use. The
determined with [Ru(bpy)3](PF6)2 (bpy
acetonitrile as a reference (ΦPL = 0.062)21 and calculated according
to the following equation: Φs = Φr(Br/Bs)(ns/nr)2(Ds/Dr), where the
subscripts s and r refer to sample and reference standard solution
respectively, n is the refractive index of the solvents, D is the
integrated intensity, and Φ is the luminescence quantum yield. The
quantity B was calculated by B = 1 – 10−AL, where A is the
absorbance at the excitation wavelength and L is the optical path
length. The solidꢀstate (PS thin film) PL quantum yields of the
platinum complexes were determined by the integratingꢀsphere
method.22,23
10 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 2012

Page 11 of 14
Journal Name
Journal of Materials Chemistry C
View ArticAle ROnTliInCeLE
DOI: 10.1039/C4TC01791A
syntheses of ligands and platinum complexes are summarized in 126.70, 124.54, 123.60, 121.71, 121.12, 109.36, 106.62, 105.25,
Scheme 2. The detailed procedure and structural characterization 89.91, 26.98. EIꢀMS: calcd. 413.14, m/z = 413.10 (M+).
data of the new compounds are shown below.
General synthesis procedure of XND ligands.
General synthesis procedure of pre-XND.
Compound pre-XND (1~2 g) in diphenyl ether (35 mL) was heated
To a mixture of 4ꢀsubstituted pyridineꢀ3ꢀamine 4OPh, 4pp, or 4Cz (1 at 260 oC and stirred under nitrogen atmosphere for 10ꢀ60 min.
equivalent) and Meldrum’s acid 2,2ꢀdimethylꢀ[1,3]dioxaneꢀ4,6ꢀ During the reaction, the colour of the solution changed from orange
dione (1.2 equivalent) was added triethyl orthoformate or triethyl yellow to dark brown or black. After cooling to room temperature,
orthoacetate (6 equivalent). The mixture was then heated at reflux the reaction solution was filtered to isolate solid product. The solid
under nitrogen for 4 h. After cooling to room temperature, the was rinsed with diphenyl ether and subjected to purification by zoneꢀ
reaction mixture was removed by vacuum distillation. The resulting temperature sublimation.
solid was purified by flash column chromatography (silica gel, ethyl
acetate/dichloromethane: 1/1) to afford the intermediate pre-XND.
4-Hydroxy-2,8-dimethyl-1,5-naphthyridine
(mmND).
The
specific amounts of chemicals used: pre-mmND (2 g, 7.2 mmol).
1
The product was obtained as a white solid (0.9 g, 71%). H NMR
2,2-Dimethyl-5-(1-(4-methylpyridin-3-ylamino)ethylidene)-1,3-
dioxane-4,6-dione (pre-mmND). The specific amounts of (400 MHz, CD3OD): δ 8.52 (d, 1H, J = 4.48 Hz), 7.51 (d, 1H, J =
chemicals used: 3ꢀaminoꢀ4ꢀmethylpyridine (2.0 g, 18.5 mmol), 4.8 Hz), 6.34 (s, 1H), 2.62 (s, 3H), 2.52 (s, 3H). 13C NMR (100
Meldrum’s acid (3.2 g, 22.2 mmol) and triethyl orthoacetate (18.0 g, MHz, CD3OD): δ 153.52, 147.39, 139.95, 139.08, 137.65, 128.73,
111.0 mmol). The product (pre-mmND) was obtained as a pale 112.49, 20.05, 17.31. EIꢀMS: calcd. 174.08, m/z = 174.08 (M +).
1
yellow solid (3.8 g, 75%). H NMR (400 MHz, CDCl3): δ 12.73 (s,
1H), 8.52 (d, 1H, J = 4.80 Hz), 8.39 (s, 1H), 7.30 (d, 1H, J = 4.96 4-Hydroxy-8-phenoxy-1,5-naphthyridine (OPhND). The specific
Hz), 2.50 (s, 3H), 2.31 (s, 3H), 1.76 (s, 6H). 13C NMR (100 MHz, amounts of chemicals used: pre-OPhND (2.5 g, 7.4 mmol). The
1
CDCl3): δ 173.98, 167.60, 162.53, 149.50, 147.67, 143.81, 132.54, product was obtained as a white solid (1.1 g, 63%). H NMR (400
125.75, 103.02, 86.48, 26.63, 19.43, 17.33. FABꢀMS: calcd. 276.11, MHz, CD3OD): δ 8.51 (d, 1H, J = 5.12 Hz), 8.02 (d, 1H, J = 7.28
m/z = 277.1 (M+H+).
Hz), 7.58 (t, 2H, J = 6.28 Hz), 7.41 (t, 1H, J = 7.34 Hz), 7.32 (d, 2H,
J = 8.24 Hz), 6.89 (d, 1H, J = 5.28 Hz), 6.57 (d, 1H, J = 7.24 Hz).
13C NMR (100 MHz, CD3OD): δ 179.28, 157.41, 154.82, 148.83,
5-((2-Phenoxyphenylamino)methylene)-2,2-dimethyl-1,3-
dioxane-4,6-dione (pre-OPhND). The specific amounts of 142.63, 141.08, 131.80, 130.68, 127.73, 122.15, 113.15, 110.59. EIꢀ
chemicals used: 4ꢀphenoxypyridinꢀ3ꢀamine (3a) (2.0 g, 10.7 mmol), MS: calcd. 238.07, m/z = 238.07 (M +).
Meldrum’s acid (1.9 g, 13.2 mmol) and triethyl orthoformate (9.6 g,
64.8 mmol). The product (pre-OPhND) was obtained as a white 4-Hydroxy-8-piperidino-1,5-naphthyridine (ppND). The specific
1
solid (2.8 g, 77%). H NMR (400 MHz, CDCl3): δ 11.48 (d, 1H, J = amounts of chemicals used: pre-ppND (1.5 g, 4.5 mmol). The
1
13.80 Hz), 8.75 (d, 1H, J = 14.24 Hz), 8.64 (s, 1H), 8.29 (d, 1H, J = product was obtained as a pale yellow solid (0.5 g, 48%). H NMR
5.52 Hz), 7.46 (t, 2H, J = 7.82 Hz), 7.31 (t, 1H, J = 7.38 Hz), 7.13 (400 MHz, CD3OD): δ 8.47 (br, 1H), 8.04 (d, 1H, J = 6.88 Hz), 7.27
(d, 2H, J = 8 Hz), 6.68 (d, 1H, J = 5.56 Hz), 1.73 (s, 6H). 13C NMR (d, 1H, J = 4.28 Hz), 6.53 (d, 1H, J = 6.96 Hz), 1.89 (m, 4H), 1.73
(100 MHz, CDCl3): δ 165.27, 163.19, 154.97, 153.05, 152.27, (m, 2H). 13C NMR (125 MHz, CD3OD): δ 155.19, 147.67, 147.22,
148.74, 139.34, 130.45, 126.33, 125.44, 120.79, 110.27, 105.30, 143.06, 134.49, 116.26, 115.81, 112.81, 54.07, 26.92, 25.25. EIꢀ
88.95, 27.12. FABꢀMS: calcd. 340.1, m/z = 341.1 (M+H+).
MS: calcd. 229.12, m/z = 229.12 (M +).
4-Hydroxy-8-carbazol-1,5-naphthyridine (CzND). The specific
5-((2-(Piperidin-1-yl)phenylamino)methylene)-2,2-dimethyl-1,3-
dioxane-4,6-dione (pre-ppND). The specific amounts of chemicals amounts of chemicals used: pre-CzND (2.0 g, 4.8 mmol). The
1
used: 4ꢀ(piperidinꢀ1ꢀyl)pyridinꢀ3ꢀamine (3b) (1.5 g, 8.5 mmol), product was obtained as a brown solid (0.7 g, 46%). H NMR(400
Meldrum’s acid (1.5 g, 10.4 mmol) and triethyl orthoformate (7.5 g, MHz, CD3OD) : δ 8.94 (d, 1H, J = 4.8 Hz), 8.24 (d, 2H, J = 8.0 Hz),
50.6 mmol). The product (pre-ppND) was obtained as a white solid 7.85 (d, 1H, J = 4.8 Hz), 7.44 (t, 2H, J = 7.8 Hz), 7.37 (t, 2H, J = 7.6
1
(1.6 g, 57%). H NMR (400 MHz, CDCl3): δ 11.32 (d, 1H, J = 13.24 Hz), 7.12 (d, 2H, J = 8.0 Hz), 6.61 (d, 2H, J = 7.2 Hz). 13C NMR
Hz), 8.73 (d, 1H, J = 14.32 Hz), 8.50 (s, 1H), 8.35 (d, 1H, J = 5.24 (125 MHz, CD3OD): δ 179.13, 164.96, 159.14, 157.56, 148.90,
Hz), 6.96 (d, 1H, J = 5.32 Hz), 2.91 (t, 4H, J = 5.24 Hz), 1.81 (m, 145.86, 144.55, 144.39, 144.12, 142.29, 139.30, 130.89, 127.85,
4H), 1.72 (s, 6H), 1.60 (t, 2H, J = 5.76). 13C NMR (100 MHz, 126.94, 126.06, 123.01, 122.46, 121.77, 113.30, 111.09. EIꢀMS:
CDCl3): δ 165.21, 163.30, 151.17, 148.59, 138.56, 128.82, 114.83, calcd. 311.1, m/z= 311.1 (M +).
105.13, 88.15, 52.30, 27.05, 25.66, 23.77. FABꢀMS: calcd. 331.15,
m/z = 332.2 (M+H+).
General procedure for synthesis of FPtXND complexes.
5-((4-(9H-Carbazol-9-yl)pyridin-3-ylamino)methylene)-2,2-
dimethyl-1,3-dioxane-4,6-dione (pre-CzND). The specific amounts
of chemicals used: 4ꢀ(9Hꢀcarbazolꢀ9ꢀyl)pyridinꢀ3ꢀamine (3c) (2.0 g,
7.7 mmol), Meldrum’s acid (1.3 g, 9.0 mmol) and triethyl
orthoformate (6.9 g, 46.6 mmol). The product (pre-CzND) was
The Pt complex (FPtCl)2 were prepared following literature
procedures.26 The K2PtCl4 and 2.5 equivalent of F ligand were
mixed in a 3:1 mixture of 2ꢀethoxyethanol and water. The mixture
was heated to 80 oC for 16 h. The desired (FPtCl)2 were precipitated
in the water. The resulting yellowꢀgreenish powder was filtered and
was subsequently reacted with XND ligand without further
purification. A stirred mixture of (FPtCl)2 (1 equivalent), Na2CO3
(10 equivalent) and XND ligand (2.1 equivalent) in 2ꢀethoxyethanol
was heated to 80 oC for 16 h. After cooling, the solution was
concentrated under reduced pressure. The resultant residue was
subjected to column chromatography (silica gel, CH2Cl2/MeOH
15:1(v/v)) to afford product.
1
obtained as a white solid (2.1 g, 66%). H NMR (400 MHz, CDCl3):
δ 10.87 (d, 1H, J = 13.6 Hz), 9.00 (s, 1H), 8.75 (d, 1H, J = 5.2 Hz),
8.55 (d, 2H, J = 13.6 Hz), 8.17 (d, 1H, J = 5.2 Hz), 7.57 (d, 1H, J =
5.2 Hz), 7.44 (t, 2H, J = 7.6 Hz), 7.36 (t, 2H, J = 7.6 Hz), 7.11 (d,
2H, J = 7.6 Hz), 1.57 (s, 6H).13C NMR (100 MHz, CDCl3) δ 164.40,
162.75, 152.06, 150.32, 148.59, 141.08, 139.30, 136.31, 132.23,
This journal is © The Royal Society of Chemistry 2012
J. Name., 2012, 00, 1-3 | 11

Journal of Materials Chemistry C
Page 12 of 14
VJieowuArrtnicalelONnlainme e
ARTICLE
DOI: 10.1039/C4TC01791A
to thank Dr. YungꢀTing Chang for the measurement of
FPtmmND. The specific amounts of chemicals used: (FPtCl)2 emission quantum yields of samples in thin film.
(0.150 g, 0.18 mmol), Na2CO3 (0.190 g, 1.80 mmol) and mmND
(0.066 g, 0.38 mmol). The product was obtained as a yellow solid
References
(0.120 g, 60%). 1H NMR (400 MHz, CD3Cl): δ 9.28 (d, 1H, J = 5.36
1. (a) M A. Baldo, M. E. Thomson and S. R. Forrest, Nature, 2000, 403,
Hz), 8.73 (d, 1H, J = 5.40 Hz), 7.97 (d, 1H, J = 8.24 Hz), 7.86 (t, 1H,
J = 7.80 Hz), 7.42 (d, 1H, J = 5.32 Hz), 7.17 (t, 1H, J = 6.46 Hz),
6.96 (dd, 1H, J = 9.48 Hz), 6.71 (s, 1H), 6.62 (td, 1H, J = 10.46 Hz),
2.78 (s, 3H), 2.62 (s, 3H). 13C NMR (100 MHz, CD3Cl): δ 162.79,
150.54, 149.40, 144.69, 139.15, 125.65, 124.30, 122.01, 121.81,
121.46, 114.35, 112.21, 99.64, 99.38, 99.11, 30.91, 25.39, 17.46.
HRꢀESIꢀMS: calcd. 558.08, m/z = 558.08 (M+). Anal. Found (calcd)
for C21H15F2N3OPt: C 44.63 (45.17), H 2.78 (2.71), N 7.25 (7.52).
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A. B. Padmaperuma, Adv. Funct. Mater., 2011, 21, 3250.
(0.170 g, 0.20 mmol), Na2CO3 (0.214 g, 2.00 mmol) and OPhND
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(0.101 g, 0.42 mmol). The product was obtained as an orangeꢀred
solid (0.190 g, 76%). H NMR (400 MHz, CD3Cl): δ 9.11 (d, 1H, J
1
= 5.36 Hz), 8.51 (t, 2H, J = 5.60 Hz), 7.84 (m, 2H), 7.54 (t, 2H, J =
7.60 Hz), 7.38 (m, 3H), 7.07 (t, 1H, J = 6.00 Hz), 6.80 (d, 1H, J =
5.20 Hz), 6.70 (d, 1H, J = 9.6 Hz), 6.61 (d, 1H, J = 6 Hz), 6.54 (t,
1H, J = 10.4 Hz). 13C NMR (100 MHz, CD3Cl): δ 173.43, 163.86,
163.39, 163.32, 153.59, 153.43, 149.29, 147.90, 146.93, 138.93,
130.53, 129.43, 128.80, 126.57, 121.63, 114.06, 113.89, 113.22,
106.70, 99.51, 99.24, 98.98. HRꢀESIꢀMS: calcd. 622.08, m/z =
623.09 (M+H+). Anal. Found (calcd) for C25H15F2N3O2Pt: C 48.56
(48.24), H 2.50 (2.43), N 6.62 (6.75).
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FPtppND. The specific amounts of chemicals used: (FPtCl)2 (0.150
g, 0.18 mmol), Na2CO3 (0.190 g, 1.80 mmol) and ppND (0.086 g,
0.38 mmol). The product was obtained as a yellow solid (0.087 g,
47%). 1H NMR (400 MHz, CD3Cl): δ 9.28 (d, 1H, J = 5.36 Hz), 8.48
(d, 1H, J = 6.40 Hz), 8.27 (d, 1H, J = 5.24 Hz), 7.93 (d, 1H, J = 8.04
Hz), 7.80 (t, 1H, J = 7.58 Hz), 7.11 (t, 1H, J = 6.34 Hz), 6.94 (d, 1H,
J = 9.08 Hz), 6.77 (d, 1H, J = 5.28 Hz), 6.70 (d, 1H, J = 6.40 Hz),
6.58 (t, 1H, J = 9.82 Hz), 3.99 (br, 4H), 1.79 (br, 6H). 13C NMR
(100 MHz, CD3Cl): δ 173.40, 164.08, 163.95, 163.55, 163.48,
161.54, 161.42, 159.22, 155.65, 149.36, 149.27, 147.04, 146.01,
143.33, 143.27, 139.54, 138.74, 129.54, 122.03, 121.84, 121.44,
114.55, 114.35, 112.04, 106.78, 99.31, 99.05, 98.78, 51.51, 25.88,
24.64. HRꢀESIꢀMS: calcd. 613.13, m/z = 613.13 (M+). Anal. Found
(calcd) for C24H20F2N4OPt: C 46.81 (46.98), H 3.22 (3.29), N 9.01
(9.13).
FPtCzND. The specific amounts of chemicals used: (FPtCl)2 (0.150
g, 0.18 mmol), Na2CO3 (0.190 g, 1.80 mmol) and CzND ( 0.117 g,
0.38 mmol). The product was obtained as an orange solid (0.162 g,
65%). 1H NMR (400 MHz, CD3Cl): δ 9.38 (d, 1H, J = 5.60 Hz), 9.12
(d, 1H, J = 5.60 Hz), 8.47 (d, 1H, J = 5.60 Hz), 8.13 (d, 2H, J = 7.60
Hz), 8.06 (d, 1H, J = 8.00 Hz), 7.91 (m, 2H), 7.40 (m, 6H), 7.23 (m,
1H), 7.03 (dd, 1H, J = 9.20 Hz), 6.95 (d, 1H, J = 5.20 Hz), 6.68 (td,
1H, J = 9.20 Hz). 13C NMR (125 MHz, CD3Cl): δ 174.27, 164.01,
161.82, 161.74, 161.63, 159.67, 159.57, 155.06, 149.74, 149.13,
147.03, 146.51, 142.67, 142.06, 140.82, 139.77, 129.92, 126.35,
125.28, 122.43, 122.27, 121.95, 121.71, 120.59, 114.66, 114.51,
113.58, 111.87, 100.22, 100.01, 99.79 HRꢀESIꢀMS: calcd. 695.11,
m/z = 696.12 (M+H+). Anal. Found (calcd) for C31H18F2N4OPt: C
53.34 (53.53), H 2.61 (2.61), N 8.15 (8.05).
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P21/c, Z = 4, F(000) = 1192. Cell dimendions: a = 14.9476(8) Å, b =
19.1171(8) Å, c = 6.8875(3) Å, α = 90o, β = 98.290(4)o, γ = 90o, V =
1947.57(16) Å3, 2θmax = 50.0o, ρcacld = 2.123 mg mꢀ3. Of 19303
Acknowledgements
We thank the Ministry of Science and Technology (NSC 101ꢀ
2113ꢀMꢀ001ꢀ004ꢀMY2), Taiwan International Graduate
Program (TIGP) of Academia Sinica, Academia Sinica, and
National Taiwan University for financial support. We also want
12 | J. Name., 2012, 00, 1-3
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DOI: 10.1039/C4TC01791A
reflections, 5135 were independence, 298 parameters, R (Fo) = 0.0316
(for reflections with I > 2σ(I)), Rw (Fo) = 0.0493 (for reflections with I >
2σ(I)). The GoF on F2 was equal 1.030. Crystal data for FPtCzND:
C62H36F4N8O2Pt2: Fw = 1390.22, monoclinoc, C2/c, Z = 4, F(000) =
5376. Cell dimendions: a = 51.3810(14) Å, b = 7.9870(2) Å, c =
26.1603(7) Å, α = 90o, β = 114.761(2)°, γ = 90o, V = 9748.7(5) Å3, 2θmax
= 50.0o, ρcacld = 1.896 mg mꢀ3. Of 105284 reflections, 9960 were
independence, 703 parameters, R (Fo) = 0.0282 (for reflections with I >
2σ(I)), Rw (Fo) = 0.0707 (for reflections with I > 2σ(I)). The GoF on F2
was equal 1.109. CCDCꢀ1010105 and CCDCꢀ1010104 contain the
supplementary crystallographic data of FPtOPhND and FPtCzND,
respectively. These data can be obtained free of charge via
www.ccd.cam.ac.uk/conts/retrieving.html (or from the Cambridge
Crystallographic Data Centre, 12, Union Road, Cambridge CB21EZ,
UK; fax: (+44)1223ꢀ336ꢀ033; or deposit@ccdc.cam.ac.uk).
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Voltage independent CIE and superb CRI of hybrid white OLEDs based on platinum
complex single dopant