Synthesis and characterization of 9-(fluoren-2-yl)anthracene derivatives as efficient non-doped blue emitters for organic light-emitting diodes

Article abstract of DOI:10.1002/ejoc.201300165

A series of 9-(fluoren-2-yl)anthracene derivatives bearing either thiophene (FATh), triphenylamine (FAT and FATT) or pyrene (FATP) moieties as substituents have been designed, synthesized, and characterized as non-doped blue emitters for organic light-emitting diodes (OLEDs). Their optical, electrochemical and thermal properties have been investigated, and their molecular structure-property relationships were evaluated. All FAT, FATT and FATP compounds possess combined blue-light-emitting and hole-transporting characteristics, and showed stable amorphous states with high fluorescence quantum yields in solution (up to 89 %) and strong luminance in the OLED devices, whereas FATh showed poor photoluminescent and electroluminescent properties. Efficient, non-doped blue and Alq3-based green OLEDs were fabricated and characterized. The blue and green devices with maximum luminance efficiencies and CIE coordinates of 3.17 cd A^-1 and (0.13, 0.14), and 3.81 cd A^-1 and (0.28, 0.50) were achieved, respectively, with FATT having 4-{bis[4′-(diphenylamino)biphenyl-4-yl]amino}phenyl substituents as emitting layer and hole-transporting layer, respectively. These devices also showed considerably low turn-on voltages of 3.0 and 2.6 V, respectively. New 9-(fluoren-2-yl)anthracene derivatives with combined blue-light-emitting and hole-transporting characteristics have been developed that exist in a stable amorphous state and deliver high fluorescence quantum yields. Copyright

Full text of DOI:10.1002/ejoc.201300165

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FULL PAPER
Blue Light-Emitting Diodes
New 9-(fluoren-2-yl)anthracene derivatives
with combined blue-light-emitting and
hole-transporting characteristics have been
developed that exist in a stable amorphous
state and deliver high fluorescence quan-
tum yields.
N. Prachumrak, S. Namuangruk,
T. Keawin, S. Jungsuttingwong,
T. Sudyoadsuk, V. Promarak* ......... 1–11
Synthesis and Characterization of 9-
(Fluoren-2-yl)anthracene Derivatives as Ef-
ficient Non-Doped Blue Emitters for Or-
ganic Light-Emitting Diodes
Keywords: Donor-acceptor systems / Mo-
lecular electronics / Thin films / Solid-state
structures / Nonlinear optics / Organic
light-emitting diodes
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V. Promarak et al.
FULL PAPER
DOI: 10.1002/ejoc.201300165
Synthesis and Characterization of 9-(Fluoren-2-yl)anthracene Derivatives as
Efficient Non-Doped Blue Emitters for Organic Light-Emitting Diodes
Narid Prachumrak,[a] Supawadee Namuangruk,[b] Tinnagon Keawin,[a]
Siriporn Jungsuttingwong,[a] Taweesak Sudyoadsuk,[a] and Vinich Promarak*[c]
Keywords: Donor-acceptor systems / Molecular electronics / Thin films / Solid-state structures / Nonlinear optics / Organic
light-emitting diodes
A series of 9-(fluoren-2-yl)anthracene derivatives bearing
either thiophene (FATh), triphenylamine (FAT and FATT) or
pyrene (FATP) moieties as substituents have been designed,
synthesized, and characterized as non-doped blue emitters
for organic light-emitting diodes (OLEDs). Their optical,
electrochemical and thermal properties have been investi-
gated, and their molecular structure-property relationships
were evaluated. All FAT, FATT and FATP compounds possess
combined blue-light-emitting and hole-transporting charac-
teristics, and showed stable amorphous states with high fluo-
rescence quantum yields in solution (up to 89%) and strong
luminance in the OLED devices, whereas FATh showed poor
photoluminescent and electroluminescent properties. Ef-
ficient, non-doped blue and Alq3-based green OLEDs were
fabricated and characterized. The blue and green devices
with maximum luminance efficiencies and CIE coordinates
of 3.17 cdA–1 and (0.13, 0.14), and 3.81 cdA–1 and (0.28, 0.50)
were achieved, respectively, with FATT having 4-{bis[4Ј-(di-
phenylamino)biphenyl-4-yl]amino}phenyl substituents as
emitting layer and hole-transporting layer, respectively.
These devices also showed considerably low turn-on volt-
ages of 3.0 and 2.6 V, respectively.
Introduction
terms of EL efficiencies and color purity. Therefore, one
area of continuing research in this field is the pursuit of a
stable, blue-emitting material.[5] Although many fluorescent
blue emitters have been reported, such as anthracene deriv-
atives,[6] phenylene derivatives,[7] pyrene derivatives,[8] fluor-
ene derivatives,[9] carbazole derivatives,[10] aromatic hydro-
carbons,[11] triarylamine derivatives,[12] and phosphorescent
iridium complexes,[13] there is still a clear need for further
improvements in terms of efficiency and color purity com-
pared to red and green emitters. Due to its unique chemical
and electron-rich structure, low electronic band gap and
strong blue fluorescence, anthracene has been used as a
building block to form many emissive materials.[6,14] It has
also been reported that incorporation of anthracene and its
9,10-substituted derivatives into polymer main-chains[15] or
linked as pendent groups[16] has helped to solve the problem
of preparation of films with good optical quality or to sup-
press excimer formation. To date, many kinds of
anthracene-functionalized materials have been synthesized
and considered for several applications,[17] and some of
them were found to be promising blue emitters for
OLEDs.[18] Recently, we have reported on the development
of anthracene derivatives with the combined characteristics
of blue-light-emitting and hole-transporting materials.[19]
Non-doped blue OLEDs with a maximum efficiency of
1.65 cdA–1 was attained. However, new classes of
anthracene-based blue-light emitters with improvements
in terms of efficiency and color purity remain to be ex-
plored.
Since the ground-breaking works on the first organic
light-emitting diodes (OLEDs) by Tang and co-workers in
1987,[1] OLEDs have attracted enormous attention from the
scientific community due to their high technological poten-
tial for the next generation of full-color-flat-panel displays[2]
and lighting applications.[3] In today’s developments of
OLED technologies, trends of OLED studies are mainly fo-
cused on the optimization of device structures and on de-
veloping new emitting materials. Clearly, the key point of
OLED development for full-color flat displays is to find
materials that emit pure colors of red, green and blue
(RGB) with excellent emission efficiency and high stability.
The performance of blue OELDs is usually inferior to that
of green and red OLEDs due to poor carrier injection into
the emitters,[4] and hence the electroluminescent (EL) prop-
erties of blue devices need to be improved, particularly in
[a] Center for Organic Electronic and Alternative Energy,
Department of Chemistry, Faculty of Science, Ubon
Ratchathani University,
Ubon Ratchathani 34190, Thailand
[b] National Nanotechnology Center,
130 Thailand Science Park, Paholyothin Rd., Klong Luang
Pathumthani 12120, Thailand
[c] School of Chemistry and Center of Excellence for Innovation
in Chemistry, Institute of Science, Suranaree University of
Technology, Muang District,
Nakhon Ratchasima 30000, Thailand
Fax: +66-44-224648
E-mail: pvinich@sut.ac.th
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201300165.
2
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9-(Fluoren-2-yl)anthracene Derivatives
In this work, we prepared a series of blue-light-emitting acid was cross-coupled with either [4-(diphenylamino)-
small molecules based on 9-(fluoren-2-yl)anthracene phenyl]boronic acid or (thiophen-2-yl)boronic acid in the
bearing thiophene, triphenylamine and pyrene moieties as presence of [Pd(PPh3)4] as catalyst and 2 m Na2CO3 as base
substituents. Their physical and photophysical properties in tetrahydrofuran (THF) to give 9-(9,9-dihexylfluoren-2-
were investigated with the aim of understanding their struc- yl)-10-[4-(diphenylamino)phenyl]anthracene (FAT) and 9-
ture-property relationships and developing novel molecular (9,9-dihexylfluoren-2-yl)-10-(thiophen-2-yl)anthracene
π-conjugated materials. The introduction of planar thio- (FATh), respectively, as light-yellow solids in good yields.
phene would allow a long π-conjugation system to be From FAT, the triphenylamine- and pyrene-functionalized
achieved, whereas integration of the bulky triphenylamine molecules, namely 9-(4-{bis[4Ј-(diphenylamino)biphenyl-4-
could suppress aggregation of the planar anthracene ring, yl]amino}phenyl)-10-(9,9-dihexylfluoren-2-yl)anthracene
as well as improve the hole-carrier injection ability and (FATT) and 9-(4-{bis[4-(pyren-1-yl)phenyl]amino}phenyl)-
thermal stability of the anthracene.[20] Incorporation of a 10-(9,9-dihexylfluoren-2-yl)anthracene (FATP), respec-
pyrene unit, which is a highly blue fluorescent chromo- tively, were synthesized in two steps. Bromination of FAT
phore, into the cruciform of this platform is an effective with N-bromosuccinimide (NBS) in THF provided 9-{4-
way to maintain the high blue emissive ability of pyrene [bis(4-bromophenyl)amino]phenyl}-10-(9,9-dihexylfluoren-
in the solid state, which significantly impacts the emission 2-yl)anthracene (3) in 96% yield followed by cross-coupling
behavior of materials and devices. Fluorene also has a of the resulting dibromo derivative 3 with either (pyren-2-
number of advantages, including its capability to emit in yl)boronic acid or [4-(diphenylamino)phenyl]boronic acid
the blue part of the visible spectrum, and its chemical and catalyzed by [Pd(PPh3)4]/Na2CO3 afforded FATP and
photochemical stability.[9,21] Investigations on OLED device FATT in good yields (54–69%) as yellow and light-yellow
fabrication and characterization of these materials are also solids, respectively. The chemical structures and purities of
described.
these materials were characterized unambiguously by NMR
and IR spectroscopy and mass spectrometry. All had good
solubility in most organic solvents at room temperature, re-
sulting from their bulky structures and the presence of n-
hexyl groups at C-9 of the fluorene ring. As a result, no
crystallization thin film should be obtained from solution
Results and Discussion
Synthesis and Quantum Chemical Calculations
The target anthracene derivatives were synthesized as il- casting.
lustrated in Scheme 1. 9-Bromo-10-(9,9-dihexylfluoren-2-
The optimized structures of FATh, FAT, FATT and
yl)anthracene (2) obtained from the reaction of 2-iodo-9,9- FATP calculated by the TDDFT/B3LYP/6-31G(d,p)
dihexylfluorene (1) and (10-bromoanthracen-9-yl)boronic method[22] revealed that all molecules adopted noncoplanar
Scheme 1. Synthesis of the 9-(fluoren-2-yl)anthracene derivatives.
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Table 1. Physical data of the materials.
[a]
[a]
[c]
Compd.
λabs
λem
λe[b] ΦF
Stokes shift Tg/Tc/Tm/T5d
E1/2 vs. Ag/Ag+
EOX
Eg
Eg calcd. HOMO/LUMO
onset
[V][f]
[nm]
[nm] [nm]
[nm][d]
[°C][e]
[V][f]
[eV][g]
[eV][h]
[eV][i]
FATh
FAT
359, 378, 398
359, 380, 399
439 439 0.12
484 458 0.73
525 471 0.80
489 469 0.89
41
85
125
89
–/115/209/330
79/–/–/390
147/–/–/401
1.20, 1.45
0.95, 1.21
0.73, 0.93, 1.11, 1.27
1.12
0.88
0.66
0.86
2.96
2.90
2.88
2.90
3.11
2.93
2.92
3.10
–5.56/–2.60
–5.32/–2.44
–5.10/–2.22
–5.30/–2.40
FATT 365, 381, 401(sh)
FATP 364, 379, 400(sh)
212/–/–/434 0.74 (Epc), 0.90, 1.14, 1.66
[a] Measured in CH2Cl2. [b] Measured in thin film on quartz substrate. [c] Measured in CH2Cl2 with quinine sulfate as a standard. [d]
max
Calculated from the difference of λabs
and λemmax. [e] Measured by DSC/TGA at a heating rate of 10 °C min–1. [f] Obtained from CV
at a scan rate of 50 mVs–1. [g] Estimated from the optical absorption edge, Eg = 1240/λonset. [h] Obtained from quantum calculations by
using TDDFT/B3LYP/6-31G(d,p). [i] Calculated by HOMO = –(4.44 + EOXonset), and LUMO = HOMO Eg, where EOX
is the onset
onset
potential of the oxidation.
conformations. Particularly, the planar anthracene unit was real situation is that an accurate description of the lowest
twisted nearly perpendicular to the adjacent thiophene, singlet excited state requires a linear combination of a
fluorene, and triphenylamine moieties because of steric re- number of excited configurations.
pulsion between the anthracene peri-hydrogen atoms (1,8-
and 4,5-positions) and hydrogen atoms of those aromatic
Optical Properties
rings. Such structural characteristics can influence some of
their electronic and physical properties such as a suppres-
sion of the conjugation. As depicted in Figure 1 (see also
the Supporting Information), in the lowest unoccupied mo-
lecular orbitals (LUMO) of all compounds, the excited elec-
trons locate only on electron-rich and electron-deficient an-
thracene moieties. In the highest occupied molecular orbit-
als (HOMO) of FATh and FAT, π-electrons locate on the
anthracene and thiophene/triphenylamine moieties, whereas
in the HOMO orbitals of FATT and FATP, π-electrons are
delocalized mainly over the donor triphenylamine/tri-
phenylamine and triphenylamine/pyrene peripheries,
respectively. Participation of the fluorene ring in the π-con-
jugation system was diminished in all cases. The HOMO–
LUMO energy gaps (Eg calcd.) were calculated, and the val-
ues deviated slightly from those obtained from the experi-
mental results estimated from the optical edge (Table 1).
Optical properties of FATh, FAT, FATT and FATP were
investigated in CH2Cl2 solution and thin film coated on
quartz substrates. The results are presented Figure 2 and
summarized in Table 1.
Figure 2. (a) UV/Vis absorption spectra in CH2Cl2. (b) PL spectra
in CH2Cl2 (line + symbol) and in thin film on quartz substrates
(line).
Their UV/Vis spectra showed two absorption bands,
which were assigned in terms of the strong absorption band
in the region of 250–320 nm corresponding to the π-π* local
electron transition of the individual aromatic units, and the
absorption bands at longer wavelengths (350–425 nm) at-
tributed to the characteristic π-π* electron transition of the
anthracene. The intensities of the latter bands of FATT and
FATP are more intense than those of FATh and FAT.
The energy gaps (Eg) of the triphenylamine-substituted
anthracenes FAT and FATT estimated from the optical on-
set were found to be identical (2.90 eV), whereas the Eg of
FATP was slightly lower (2.89 eV), and the Eg of FATh was
as high as 2.96 eV. These compounds fluoresced in solution
from bright-blue to blue-green with featureless photolumi-
nescence (PL) spectra, which is similar to what has been
observed for most 9,10-diphenylanthracenes.[6] The solution
Figure 1. The HOMO and LUMO orbitals calculated by the
TDDFT/B3LYP/6-31G(d,p) method.
Factors responsible for the discrepancies include the fact PL spectra of FAT and FATP redshifted with respect to
that the orbital energy difference between HOMO and that of FATh, whereas the PL spectra of FATT were further
LUMO is still an approximate estimation of the transition redshifted. These observations were in agreement with the
energy, because the transition energy also contains signifi- results of theoretical and UV/Vis experiments. These mate-
cant contributions from some two-electron integrals. The rials showed a slight Stokes shift (41–125 nm), suggesting
4
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9-(Fluoren-2-yl)anthracene Derivatives
less energy loss during the relaxation process and efficient
The CV curve of FATh showed two irreversible oxidation
fluorescence. The thin-film PL emission spectrum of FATh, processes and identical CV curves under multiple scans,
shown in Figure 2b, was similar to its solution PL spectrum demonstrating the stability of the molecule (Figure 3b). The
in terms of line shape, emission λmax and full-width at half- first oxidation wave corresponded to the removal of elec-
maximum, thus indicating that less, if any, solid-state pack- trons from the terminal thiophene ring to form a radical
ing occurred in this case due to its bulky molecular struc- cation. No oxidation peak at lower potential due to a di-
ture. In the cases of FAT, FATT and FATP, having more merization coupling of such species was detected, unlike
bulky structures, their thin-film PL spectra exhibited hyp- what is observed in most cases of α-unsubstituted short
sochromic shifts of 20–54 nm compared with their corre- oligothiophenes such as FTh,[25] which, under repeated CV
sponding solution spectra. This result may also be attrib- scans, suffered an electrochemical oxidative dimerization re-
uted to the aforementioned solid-state packing force, which action of the thiophene ring. In our case, this electrodimer-
prohibits the electron-vibration coupling between the tri- ization reaction could be prevented by steric hindrance gen-
phenylamine substituent and the anthracene photoactive erated by the nearby anthracene moiety. The CV curves of
unit. The solution fluorescence quantum yields (ΦF) of the triphenylamine-substituted anthracenes FAT and FATT
FATh, FAT, FATT and FATP were 0.12, 073, 0.80 and 0.89, were found to exhibit two and four well-separated (quasi-)
respectively. The results indicated that direct attachment of reversible oxidation processes at 0.95 and 1.21 V, and 0.73,
the thiophene ring to the luminous anthracene moiety in 0.93, 1.11 and 1.27 V, respectively, whereas the CV curve of
FATh lowered the ΦF of the anthracene (ΦF = 0.35– FATP showed three irreversible processes at 0.90, 1.14, and
0.40).[23] The decrease of ΦF with increasing numbers of 1.66 V, with an additional peak at a lower potential (0.74 V)
thiophene units is usually observed in most of the thio- on the cathodic scan (Epc). The first oxidation wave was
phene oligomers as the molecule becomes more planar and assigned to the removal of electrons from the tri-
likely to undergo fluorescence quenching by intermolecular phenylamine moiety resulting in the formation of tri-
π-π stacking.[24] In contrast, replacing the thiophene ring phenylamine radical cations (TPA+·). This oxidation poten-
with electron-donating triphenylamine in FAT and FATT tial was found to decrease from 0.95 (FAT) to 0.90 (FATP)
significantly increased the ΦF and the value was even higher and to 0.73 V (FATT) due to the extended delocalization of
in FATP, having highly fluorescent pyrene as peripheral the π-electrons between the triphenylamine and pyrene in
substituents.
FATP, and the two triphenylamines in FATT, as observed
in the TDDFT calculation results. The multiple CV scans
of both FAT and FATT revealed identical CV curves, indi-
cating that no oxidative coupling (or a weak oxidative cou-
pling if any) at the p-phenyl rings of the peripheral tri-
phenylamine led to electropolymerization and that they are
electrochemically stable molecules. Usually, this type of
electrochemical coupling reaction is detected in tri-
phenylamine derivatives with an unsubstituted para posi-
tion of the phenyl ring such as 2,7-bis{2-[4-(diphenyl-
amino)phenyl]-1,3,4-oxadiazol-5-yl}-9,9-bis(n-hexyl)fluor-
ene.[26] In the cases of FAT and FATT, the steric bulk and
resultant stability of the radical cation formed play an im-
portant role in preventing both molecules from undergoing
such an electrochemical reaction. The radical cations TPA+·
of FAT and FATT are stabilized by electron delocalization
from TPA+· through the adjacent anthracene ring and tri-
phenylamine moiety, respectively, as depicted in Figure 4.
The significant steric effects on the radical center formed
prevent such a radical from undergoing radical-radical di-
merization coupling. However, the radical cation of FATP
is stabilized by electron delocalization through the substi-
tuted electron-rich pyrene ring to form a pyrene radical cat-
ion (Py+·), which is relatively less stable compared with the
TPA+· of FAT and FATT. The Py+· readily undergoes a rad-
ical-radical dimerization coupling to form a stable neutral
pyrene dimer, as indicated by the presence of the cathodic
peak at 0.74 V in their first CV scan and an increasing
change in the CV curves under repeated CV scans (Fig-
ure 3d). However, this type of radical-radical coupling reac-
tion will become inactive in nondiffusion systems or the
solid state. Moreover, under these CV experiment condi-
Electrochemical and Thermal Properties
The electrochemical behavior of all compounds was in-
vestigated by cyclic voltammetry (CV); the resulting data
are shown in Figure 3 and summarized in Table 1.
Figure 3. (a) CV curves, and multiple-scan CV curves of (b) FATh,
(c) FATT, and (d) FATP measured in CH2Cl2/nBu4NPF6 at a scan
rate of 50 mVs–1.
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Figure 4. Proposed oxidation and electrochemical reaction of the triphenylamine and pyrene moieties.
tions, no distinct reduction process was observed in any (150 nm), in which the materials developed here were used
case. as the blue emitting layer (EML). Conductive polymer
The HOMO and LUMO energy levels of FATh, FAT, poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate)
FATT and FATP were calculated from the oxidation onset
potentials (Eonset) and energy gaps (Eg), and the results are
summarized in Table 1. The HOMO levels of these materi-
als ranged from 5.10 to 5.56 eV, matching well with the
work functions of the gold (Au) or indium tin oxide (ITO)
electrodes and hence favoring the injection and transport of
holes.
The thermal properties of FATh, FAT, FATT and FATP
were investigated by thermal gravimetric analysis (TGA)
and by differential scanning calorimetry (DSC) (Table 1
and Figure S3). These results suggest that all compounds
are thermally stable materials with 5% weight loss tempera-
tures (T5d) well over 330 °C. The DSC thermogram of
Figure 5. EL (line + symbol) and PL (line) spectra of the materials
and their OLED devices.
FATh showed a broad exothermic peak due to crystalli-
zation (Tc) at 115 °C followed by an endothermic melting
peak (Tm) at 209 °C. Compounds FAT, FATT and FATP,
bearing triphenylamine moieties as substituents, exhibited
different thermal behavior. The asymmetric and bulky na-
ture of this group may play an additional role in molecular
packing. Their DSC thermograms revealed only an endo-
thermic baseline shift owing to glass transition (Tg) with no
crystallization and melting peaks at higher temperature.
The Tg values increase from 79 °C for FAT to 147 °C for
FATT and to 212 °C for FATP. The ability of these materi-
als to form a molecular glass with the possibility of prepar-
ing thin films both by evaporation and by solution casting
is highly desirable for applications in electroluminescent de-
vices.
Electroluminescence Properties
To investigate the electroluminescence properties of
FATh, FAT, FATT and FATP, blue OLED devices were
fabricated with the following device structure: ITO/
PEDOT:PSS/EML(50 nm)/BCP(40 nm)/LiF(0.5 nm):Al- efficiency with current density of the fabricated blue OLEDs.
Figure 6. (a) J-V-L characteristics and (b) variation in luminance
6
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9-(Fluoren-2-yl)anthracene Derivatives
Table 2. Device characteristics of the fabricated OLEDs.
Device EML/HTL Von [V][c] V100 [V][d] λmax [nm][e]
Lmax [V] (V [cdm–2])[f]
J [mAcm–2][g]
η [cdA–1][h]
CIE (x, y)[i]
I[a]
FATh
FAT
5.2
3.8
3.0
3.3
2.6
3.5
2.8
4.2
6.9
5.2
3.9
4.5
3.8
4.4
3.8
5.4
440, 463sh
457
504 (9.4)
2621 (8.6)
8459 (8.8)
6404 (9.6)
19246 (9.6)
16667 (9.8)
24803 (10.2)
4961 (10.0)
237
436
618
0.48
1.28
3.17
1.42
3.81
2.11
3.52
0.91
0.15, 0.13
0.14, 0.13
0.13, 0.14
0.13, 0.23
0.28, 0.50
0.27, 0.46
0.28, 0.53
0.30, 0.54
II[a]
III[a]
IV[a]
V[b]
FATT
FATP
FATT
FATP
NPB
–
471
472
511
517
515
518
672
1385
1268
1517
693
VI[b]
VII[b]
VIII[b]
[a] ITO/PEDOT:PSS/EML/BCP/LiF:Al. [b] ITO/PEDOT:PSS/HTL/Alq3/LiF:Al. [c] Turn-on voltage at 1 cdm–2. [d] Voltage at luminance
of 100 cdm–2. [e] Emission maximum. [f] Maximum luminance at applied voltage. [g] Current density at maximum luminance. [h] Lumi-
nance efficiency. [i] CIE coordinates.
(PEDOT:PSS) as hole injection layer and 2,9-dimethyl-4,7- PL spectra. Device I, having FATh as EML, displayed a
diphenyl-1,10-phenanthroline (BCP) as hole-blocking layer shoulder emission peak at the longer wavelength (463 nm)
were also used to enable high-performance devices. The owing to excimer and exciplex species formed at the inter-
electroluminescent (EL) spectra and current density-volt- face of EML and HBL materials, which often occurs in
age-luminance (J-V-L) characteristics of the devices are devices fabricated from EML with planar molecular struc-
shown in Figures 5 and 6, and their electrical parameters ture. However, no such emission shoulder was observed in
are summarized in Table 2.
devices II–IV. In these cases, the formation of those species
The results revealed that FAT, FATT and FATP, having could be prevented by the steric bulk of FAT, FATT and
the electron-donating triphenylamine group attached to the FATP. Additionally, stable emission was obtained from all
9-(fluoren-2-yl)anthracene moiety, had far better EML devices, with the EL spectra not changing much over the
properties in the OLEDs than FATh, having thiophene as entire drive voltages.
the substituent, both in terms of turn-on voltage and lumi-
nance efficiency (η). The device performance of the blue
OLED devices (maximum luminance and η) matched the
observed PL quantum efficiencies of these materials
(Table 1). Fluorescence quantum yields (ΦF) of FAT, FATT
and FATP were significantly higher than that of FATh.
It has been demonstrated that the efficiency of an OLED
depends both on the balance of electrons and holes and
the ΦF of the emitter.[27] Device III, having FATT as EML,
showed the best performance with a high maximum bright-
ness of 8459 cdm–2 at 8.8 V, an η of 3.17 cdA–1 and a low
Figure 7. Schematic energy-level diagram of each material in the
turn-on voltage of 3.0 V, which is considered to be one of
the lowest turn-on voltages seen for blue OLEDs. Devices II
and IV, using FAT and FATP as EML, respectively, exhib-
devices.
As the HOMO levels of both FATT and FATP match
ited lower device performance with maximum brightness, well with the work function of ITO (4.8 eV), these com-
turn-on voltage and η of 2621 cdm–2, 3.8 V and 1.28 cdA–1, pounds may potentially serve as hole-transporting materials
and 6404 cdm–2, 3.3 V and 1.42 cdA–1, respectively. These (HTM). To test this hypothesis, double-layer green OLED
results can be explained by analysis of band energy dia- devices with the structure of ITO/PEDOT:PSS/
grams of all devices. It is found that the HOMO levels of HTL(40 nm)/Alq3(50 nm)/LiF(0.5 nm):Al(150 nm)
were
all compounds (5.32–5.56 eV) fell between those of fabricated, in which the materials developed here were used
PEDOT:PSS (5.00 eV) and BCP (6.50 eV) (Figure 7). How- as hole-transporting layers (HTL) and tris(8-hydroxyquin-
ever, there is a barrier of around 0.1 eV for holes to migrate oline)aluminum (Alq3) as the green-light-emitting (EML)
from the PEDOT:PSS/EML interface in device III, whereas and electron-transporting layers (ETL). The reference de-
such energy barriers are wider in devices II and IV (0.30– vices (devices VII and VIII) with and without a commonly
0.32 eV) and even larger in device I (0.56 eV). This suggests used commercial HTM, N,NЈ-bis(naphthalen-2-yl)-N,NЈ-di-
that migration of the hole from the PEDOT:PSS to the phenylbenzidine (NPB), as HTL was made for comparison.
EML layer is more effective in device III, resulting in the By comparison with the reference device VIII, it was found
charge efficiently recombining in the emitting layer and bet- that the incorporation of FATT and FATP in the devices
ter device performance compared with both devices II and (V and VI) as HTL not only increased the device efficienc-
IV. Under applied voltage, devices I–IV emitted a bright ies, but also significantly decreased the turn-on voltages of
blue emission with peaks centered at 404, 457, 471, and both diodes. Furthermore, their EL spectra were nearly
472, respectively (Figure 5). The electroluminescence (EL) identical. Moreover, the device characteristics in terms of
spectra of all diodes matched their corresponding thin-film luminous efficiency clearly demonstrated that the HTM
Eur. J. Org. Chem. 0000, 0–0
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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V. Promarak et al.
FULL PAPER
abilities of these materials were greater than a commonly tional materials reported such as 2,7-bis(pyren-1-yl)-9,9-
used HTM, NPB (device VII). Both devices (V and VI) ex- bis[4-(diphenylamino)phenyl]fluorene [Von = 3.3 V, η =
hibited light turn-on voltage at 1 cdm–2 in the range 2.6– 2.06 cdA–1, CIE (x, y) = (0.15, 0.13)].[5b]
3.5 V and operating voltages at 100 cdm–2 in the range 3.8–
4.4 V, indicating a good performance for all devices (Fig-
Conclusions
ure 8 and Table 2). Device V, having FATT as HTL, exhib-
ited the best performance, with a high maximum brightness
of 19246 cdm–2 for green OLED at 9.6 V, an η of
3.81 cdA–1 and a low turn-on voltage of 2.6 V, which is con-
sidered to be one of the lowest turn-on voltages found for
green OLEDs. A slightly lower device performance was ob-
served for device VI (FATP as HTL) (Table 2). Under ap-
plied voltage, both devices V and VI exhibited a bright
green emission with peaks centered at 511 and 517 nm, and
CIE coordinates of (0.28, 0.50) and (0.27, 0.46), respectively
(Figure 5b). The EL spectra of these diodes matched the
PL spectrum of Alq3, the EL of the reference devices VII
and VIII, and also other reported EL spectra of Alq3-based
devices.[28] No emission at longer wavelength owing to exci-
plex species formed at the interface of HTL and ETL mate-
rials, which often occurs in devices fabricated from HTL
with planar molecular structure, was detected.[29] From
these results and in view of the fact that a barrier for elec-
tron migration at the Alq3/HTL interface (0.60–0.78 eV) is
higher than those for hole migration at the HTL/Alq3 inter-
face (0.50–0.70 eV); hence, under the present device config-
uration of ITO/PEDOT:PSS/HTL/Alq3/LiF:Al, FATT and
FATP would act only as HTL, and Alq3 would act prefera-
bly as an electron blocker more than as a hole blocker, with
charge recombination thus confined to the Alq3 layer. More
importantly, a stable emission was obtained from both di-
odes, with the EL spectra and CIE coordinates not chang-
ing over the entire applied voltage range. Although, many
blue-emitting and hole-transporting materials have been re-
ported, in terms of the amorphous morphology, high Tg
and device efficiency, FATT is among the better bifunc-
Blue-fluorescent materials based on 9-(fluoren-2-yl)-
anthracene, having either thiophene, triphenylamine and
pyrene moieties as substituents, were successfully synthe-
sized and characterized. All were thermally stable, with de-
gradation temperatures well above 330 °C. By the inclusion
of triphenylamine and pyrene as substituents, we were able
to maintain the high emissive ability of anthracene in the
solid state, and improve the amorphous stability of these
materials. Molecules having electron-donating triphenyl-
amine groups attached to the 9-(fluoren-2-yl)anthracene
moiety displayed a combined light-emitting and hole-trans-
porting characteristic for OLED. These materials also ex-
hibited strong blue emission with fluorescent quantum effi-
ciency over 89% in solution and strong electroluminescence
in the solid state, whereas anthracene bearing thiophene as
substituent showed poor photoluminescent and electro-
luminescent properties. Efficient non-doped blue and Alq3-
based green OLEDs with maximum luminance efficiencies
and CIE coordinates of 3.17 cdA–1 and (0.13, 0.14), and
3.81 cdA–1 and (0.28, 0.50), respectively, were achieved with
FATT having 4-{bis[4Ј-(diphenylamino)biphenyl-4-yl]-
amino}phenyl substituents as emitting layer and hole-trans-
porting layer, respectively. Both devices also showed low
turn-on voltages of 3.0 and 2.6 V, respectively, which are
considered among the lowest turn-on voltages for blue and
green OLEDs. According to these characteristics, these ma-
terials, especially FATT, have sufficient potential for use in
fluorescence OLED applications.
Experimental Section
Materials and Instruments: All reagents were purchased from Ald-
rich, Acros or Fluka, and used without further purification. All
solvents were supplied by Thai companies and used without further
distillation. THF was heated to reflux with sodium and benzo-
phenone, and distilled prior to use. CH2Cl2 for electrochemical
measurements was washed with concd. H2SO4 and distilled twice
from calcium hydride. Chromatographic separations were carried
1
out on Merck silica gel 60 (0.0630–0.200 mm). H and 13C NMR
spectra were recorded with a Bruker Avance 300 MHz spectrometer
with TMS as the internal reference by using CDCl3 as solvent in
all cases. Infrared (IR) spectra were measured as potassium
bromide (KBr) discs with a Perkin–Elmer FTIR RXI spectrometer.
UV/Vis spectra were recorded as dilute solutions in CH2Cl2 with
a Perkin–Elmer UV Lambda 25 spectrometer. Photoluminescence
spectra and fluorescence quantum yields (ΦF) were recorded as di-
lute solutions in CH2Cl2 and thin films obtained by thermal evapo-
ration with a Perkin–Elmer LS 50B Luminescence Spectrometer.
Quinine sulfate solution in 0.01 m H2SO4 (ΦF = 0.54) was used as
a reference standard.[30] DSC and TGA were performed with a
Mettler DSC823e thermal analyzer and a Rigaku TG-DTA 8120
thermal analyzer, respectively, under nitrogen with heating rates of
10 °C min–1. CV was carried out with an Autolab potentiostat
Figure 8. (a) J-V-L characteristics and (b) variation in luminance
efficiency with current density of the fabricated green OLEDs.
8
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© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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9-(Fluoren-2-yl)anthracene Derivatives
PGSTAT 12 with a three-electrode system (platinum counter elec-
trode, glassy carbon working electrode and Ag/Ag+ reference elec-
(m.p. 158 °C). FTIR (KBr): ν = 2928, 1462, 1438, 1344, 1260, 1020,
˜
1
890 cm–1. H NMR (300 MHz, CDCl3): δ = 0.76–0.88 (m, 10 H),
trode) at a scan rate of 50 mVs–1 in the presence of nBu4NPF6 as 1.09–1.14 (m, 12 H), 1.95–2.01 (m, 4 H), 7.34–7.40 (m, 7 H), 7.59
a supporting electrolyte in CH2Cl2 under argon. Melting points
were measured with an Electrothermal IA 9100 series digital melt-
ing point instrument and are uncorrected. High-resolution mass
spectrometry (HRMS) analysis was performed by the Mass Spec-
trometry Unit, Mahidol University, Thailand.
(t, J = 8.8 Hz, 2 H), 7.72 (d, J = 9.0 Hz, 2 H), 7.81 (dd, J = 3.3,
2.7 Hz, 1 H), 7.89 (d, J = 7.5 Hz, 1 H), 8.62 (d, J = 8.7 Hz, 2 H)
ppm. 13C NMR (75 MHz, CDCl3): δ = 13.99, 22.47, 23.85, 29.60,
31.52, 40.37, 55.26, 119.62, 119.83, 122.92, 124.87, 125.46, 125.91,
126.54, 126.92, 127.32, 127.44, 129.73, 130.30, 131.20, 136.90,
140.81, 150.95 ppm. HRMS: calcd. for C39H42Br [M+] 589.2432;
found 589.3042.
Fabrication and Characterisation of DSSCs: Blue OLED devices
using FATh, FAT, FATT and FATP as EML with structure ITO/
PEDOT:PSS/EML(50 nm)/BCP(40 nm)/LiF(0.5 nm):Al(150 nm)
and double-layer green OLED devices using FATT, FATP and
NPB as HTL with structure ITO/PEDOT:PSS/HTL(40 nm)/
Alq3(50 nm)/LiF(0.5 nm):Al(150 nm) were fabricated and charac-
terized as follows. The patterned indium tin oxide (ITO) glass sub-
strate with a sheet resistance of 14 Ωsq–1 (purchased from Kintec
Company) was cleaned and dried at 60 °C in a vacuum oven. A
50 nm thick PEDOT:PSS layer was spin-coated on top of ITO from
a 0.75 wt.-% dispersion in water at a spin speed of 3000 rpm for
20 s and dried at 200 °C under vacuum for 15 min. Thin films of
each organic EML or HTL were then deposited on top by evapora-
tion from resistively heated alumina crucibles at an evaporation
rate of 0.5–1.0 nms–1 in a vacuum evaporator for deposition
(ES280, ANS Technology) under a base pressure of ca. 10–5 mbar.
The film thickness was monitored and recorded with a quartz oscil-
lator thickness meter (TM-350, Maxtek). A 40 nm thick layer of
BCP or a 50 nm thick layer of Alq3 was then deposited on the
organic EML or HTL, respectively, without breaking the vacuum
chamber. The chamber was then vented with dry air to load the
cathode materials and pumped back; a 0.5 nm thick layer of LiF
and a 150 nm thick layer of aluminum were then subsequently de-
posited through a shadow mask on top of the EML/HTL film
without braking vacuum to form active diode areas of 4 mm2. The
measurement of device efficiency was performed according to
M. E. Thomson’s protocol, and the external quantum efficiencies
of the device was calculated by using the procedure reported pre-
viously.[31] Current density-voltage-luminescence (J-V-L) character-
istics were measured simultaneous with a Keithley 2400 source me-
ter and a Newport 1835C power meter equipped with a Newport
818-UV/CM calibrated silicon photodiode. The EL spectra were
acquired with an Ocean Optics USB4000 multichannel spectrome-
ter. All the measurements were performed under ambient atmo-
sphere at room temperature.
9-(9,9-Dihexylfluoren-2-yl)-10-(thiophen-2-yl)anthracene
FATh (0.51 g, 76%) was synthesized from 2 and (thiophen-2-yl)-
boronic acid in a manner similar to that for 2 and obtained as a
(FATh):
light-yellow solid (m.p. 186 °C). FTIR (KBr): ν = 2930, 1458, 1440,
˜
1380, 1224, 1028, 824 cm–1. 1H NMR (300 MHz, CDCl3): δ = 0.78–
0.82 (m, 10 H), 1.12–1.18 (m, 12 H), 2.03 (t, J = 9.0 Hz, 4 H),
7.34–7.47 (m, 11 H), 7.66 (d, J = 4.8 Hz, 1 H), 7.79 (d, J = 8.7 Hz,
2 H), 7.84 (d, J = 7.8 Hz, 1 H), 7.92–7.98 (m, 3 H) ppm. 13C NMR
(75 MHz, CDCl3): δ = 14.03, 22.51, 23.89, 29.66, 31.55, 40.45,
55.27, 119.64, 119.82, 122.92, 125.10, 125.57, 126.03, 126.73,
126.91, 127.03, 127.20, 127.26, 128.66, 129.50, 129.75, 131.65,
137.40, 139.17, 139.31, 140.87, 141.05, 150.91, 151.02 ppm.
HRMS: calcd. for C43H45S [M+] 593.3197; found 593.3186.
9-(9,9-Dihexylfluoren-2-yl)-10-[4-(diphenylamino)phenyl]anthracene
(FAT): FAT (0.52 g, 79 %) was synthesized from 2 and [4-(di-
phenylamino)phenyl]boronic acid in a manner similar to that for 2
and obtained as a light-yellow solid (m.p. 146 °C). FTIR (KBr): ν
˜
= 2929, 1590, 1494, 1380, 1273, 1019, 823, 746 cm–1. 1H NMR
(300 MHz, CDCl3): δ = 0.75–0.80 (m, 10 H), 1.09–1.16 (m, 12 H),
1.98–2.03 (m, 4 H), 7.07–7.12 (t, J = 7.0 Hz, 2 H), 7.26–7.46 (m,
21 H), 7.77–7.95 (m, 6 H) ppm. 13C NMR (75 MHz, CDCl3): δ =
14.02, 22.51, 23.89, 31.55, 40.47, 55.26, 119.61, 119.78, 122.91,
123.10, 123.13, 124.71, 124.97, 126.16, 126.88, 127.10, 127.19,
129.40, 129.89, 130.10, 130.15, 132.14, 132.69, 136.92, 137.70,
140.54, 141.00, 147.17, 147.84, 150.86, 150.98 ppm. HRMS: calcd.
for C57H56N [M+] 754.4407; found 754.4386.
10-{4-[Bis(4-bromophenyl)amino]phenyl}-10-(9,9-dihexylfluoren-2-
yl)anthracene (3): To a solution of FAT (0.30 g, 0.39 mmol) in THF
(25 mL) was added NBS (0.15 g, 0.83 mmol) in small portions.
Soon after, the starting material was completely consumed, water
(10 mL) was then added, and the mixture was extracted with
CH2Cl2 (2ϫ 50 mL). The combined organic phases were washed
with water (50 mL) and brine (50 mL), dried with anhydrous
Na2SO4, filtered, and the solvents were removed to dryness. Purifi-
cation by recrystallization (CH2Cl2/MeOH) gave the product
Quantum Chemical Calculations: The ground-state geometries of all
molecules were fully optimized by using density functional theory
(DFT) at the B3LYP/6-31G(d,p) level, as implemented in
Gaussian 09.[22] TDDFT/B3LYP calculation of lowest excitation
energies were performed at the optimized geometries of the ground
states.
(0.35 g, 97%) as a light-yellow solid (m.p. 194 °C). FTIR (KBr): ν
˜
= 2990, 2686, 2520, 2410, 2360, 1726, 1586, 1422, 1266, 896 cm–1.
1H NMR (300 MHz, CDCl3): δ = 0.75–0.80 (m, 10 H), 1.09–1.26
(m, 12 H), 2.00–2.05 (m, 4 H), 7.09–7.16 (m, 4 H), 7.22–7.47 (m,
17 H), 7.58–7.67 (m, 2 H), 7.78–7.83 (m, 3 H), 7.93–7.96 (m, 1 H)
ppm. 13C NMR (75 MHz, CDCl3): δ = 14.00, 22.50, 23.89, 29.66,
31.55, 40.46, 55.41, 115.92, 116.30, 119.58, 119.63, 119.79, 119.96,
122.28, 122.95, 123.33, 123.71, 124.99, 125.11, 125.92, 126.17,
126.87, 127.15, 127.22, 127.68, 128.62, 129.86, 130.10, 131.31,
132.48, 132.58, 132.65, 133.96, 136.40, 137.58, 137.84, 140.35,
140.54, 140.60, 140.97, 146.24, 146.27, 146.84, 150.89, 150.97 ppm.
HRMS: calcd. for C57H53Br2N [MH+] 911.2524; found 912.3551.
9-Bromo-10-(9,9-dihexylfluoren-2-yl)anthracene (2): A mixture of
2-iodo-9,9-bis(n-hexyl)fluorene (1)[32] (1.28 g, 2.79 mmol), (10-
bromoanthracen-9-yl)boronic acid (0.84 g, 2.79 mmol), [Pd(PPh3)4]
(0.065 g, 0.12 mmol), and a 2 m Na2CO3 (8 mL) aqueous solution
in THF (12 mL) was degassed with N2 for 5 min. The reaction
mixture was stirred at reflux under N2 for 18 h. After cooling to
room temperature, water (50 mL) was added, and the mixture was
extracted with CH2Cl2 (2ϫ 50 mL). The combined organic phases
were washed with water (50 mL) and brine solution (50 mL), dried
with anhydrous Na2SO4, filtered, and the solvents were removed
to dryness. Purification by column chromatography on silica gel
(CH2Cl2/hexane, 1:4) followed by recrystallization (CH2Cl2/
MeOH) afforded the product (0.66 g, 52%) as a light-yellow solid
9-(4-{Bis[4-(pyren-1-yl)phenyl]amino}phenyl)-10-(9,9-dihexylfluoren-
2-yl)anthracene (FATP): FATP (0.11 g, 69%) was synthesized from
3 and (pyren-1-yl)boronic acid in a manner similar to that for 2
and obtained as a yellow-green solid (m.p. 188 °C). FTIR (KBr):
ν = 2990, 2684, 2520, 2408, 2360, 1726, 1588, 1266, 896 cm–1. H
1
˜
Eur. J. Org. Chem. 0000, 0–0
© 0000 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Pages: 11
V. Promarak et al.
FULL PAPER
H. Jiang, Y. Gao, X. Jiang, H. Lin, W. Zhao, J. Hao, Org. Lett.
2010, 12, 3874–3877.
NMR (300 MHz, CDCl3): δ = 0.76–0.80 (m, 10 H), 1.10–1.16 (m,
12 H), 1.99–2.02 (m, 4 H), 7.34–7.55 (m, 11 H), 7.63 (d, J = 8.4 Hz,
6 H), 7.72 (d, J = 8.4 Hz, 4 H), 7.83 (d, J = 8.4 Hz, 3 H), 7.97 (d,
J = 8.4 Hz, 3 H), 8.04 (t, J = 7.5 Hz, 2 H), 8.11 (d, J = 9.3 Hz, 8
H), 8.21 (t, J = 6.0 Hz, 4 H), 8.28 (d, J = 7.8 Hz, 2 H), 8.42 (d, J
= 9.3 Hz, 2 H) ppm. 13C NMR (75 MHz, CDCl3): δ = 14.03, 22.52,
23.91, 29.68, 31.57, 40.48, 55.28, 119.65, 119.80, 122.92, 124.11,
124.33, 124.77, 124.81, 125.03, 125.10, 125.44, 126.03, 126.18,
126.90, 127.13, 127.37, 127.47, 127.71, 128.56, 129.91, 130.16,
130.20, 130.51, 131.57, 132.47, 133.53, 135.87, 136.84, 137.44,
137.68, 137.73, 140.58, 141.01, 146.99, 147.03, 150.90, 150.99 ppm.
HRMS: calcd. for C89H71N [MH+] 1153.5587; found 1154.5370.
[7]
[8]
a) Z. Yang, Z. Chi, T. Yu, X. Zhang, M. Chen, B. Xu, S. Liu,
Y. Zhang, J. Xu, J. Mater. Chem. 2009, 19, 5541–5546; b) K.-
T. Wong, T. S. Hung, Y. Lin, C.-C. Wu, G.-H. Lee, S.-M. Peng,
C. H. Chou, Y. O. Su, Org. Lett. 2002, 4, 513–516; c) J.-U. Kim,
H.-B. Lee, J.-S. Shin, Y.-H. Kim, Y.-K. Joe, H.-Y. Oh, C.-G.
Park, S.-K. Kwon, Synth. Met. 2005, 150, 27–32.
a) T. Kumchoo, V. Promarak, T. Sudyoadsuk, M. Sukwattanas-
initt, P. Rashatasakhon, Chem. Asian J. 2010, 5, 2162–2167; b)
K.-C. Wu, P.-J. Ku, C.-S. Lin, H.-T. Shih, F.-I. Wu, M.-J. Hu-
ang, J.-J. Lin, I.-C. Chen, C.-H. Cheng, Adv. Funct. Mater.
2008, 18, 67–75; c) S.-I. Kawano, C. Yang, M. Ribas, S. Balus-
chev, M. Baumgarten, K. Müllen, Macromolecules 2008, 41,
7933–7937; d) H.-Y. Oh, C. Lee, S. Lee, Org. Electron. 2009,
10, 163–169.
a) A. L. Fischer, K. E. Linton, K. T. Kamtekar, C. Pearson,
M. R. Bryce, M. C. Petty, Chem. Mater. 2011, 23, 1640–1642;
b) M. C. Gather, M. Heeney, W. Zhang, K. S. Whitehead,
D. D. C. Bradley, I. McCulloch, A. J. Campbell, Chem. Com-
mun. 2008, 1079–1081; c) A. Goel, S. Chaurasia, M. Dixit, V.
Kumar, S. Prakash, B. Jena, J. K. Verma, M. Jain, R. S. Anand,
S. S. Manoharan, Org. Lett. 2009, 11, 1289–1292; d) Y.-M.
Jeon, J.-W. Kim, C.-W. Lee, M.-S. Gong, Dyes Pigm. 2009, 83,
66–71; e) Z. Zhao, X. Xu, X. Chen, X. Wang, P. Lu, G. Yu, Y.
Liu, Tetrahedron 2008, 64, 2658–2668.
a) T. Mori, T. Shinnai, M. Kijima, Polym. Chem. 2011, 2, 2830–
2834; b) Z. Yang, Z. Chi, L. Zhou, X. Zhang, M. Chen, B. Xu,
C. Wang, Y. Zhang, J. Xu, Opt. Mater. 2009, 32, 398–401; c)
N. Agarwal, P. K. Nayak, F. Ali, M. P. Patankar, K. L. Naras-
imhan, N. Periasamy, Synth. Met. 2011, 161, 466–473.
a) T. Qin, W. Wiedemair, S. Nau, R. Trattnig, S. Sax, S. Wink-
ler, A. Vollmer, N. Koch, M. Baumgarten, E. J. W. List, K.
Müllen, J. Am. Chem. Soc. 2011, 133, 1301–1303; b) F. Liu, L.-
H. Xie, C. Tang, J. Liang, Q.-Q. Chen, B. Peng, W. Wei, Y.
Cao, W. Huang, Org. Lett. 2009, 11, 3850–3853.
a) S.-L. Lai, Q.-X. Tong, M.-Y. Chan, T.-W. Ng, M.-F. Lo, S.-
T. Lee, C.-S. Lee, J. Mater. Chem. 2011, 21, 1206–1211; b) J.-
W. Park, P. Kang, H. Park, H.-Y. Oh, J.-H. Yang, Y.-H. Kim,
S.-K. Kwon, Dyes Pigm. 2010, 85, 93–98; c) Z. H. Li, M. S.
Wong, Y. Tao, J. Lu, Chem. Eur. J. 2005, 11, 3285–3293.
a) H.-J. Seo, K.-M. Yoo, M. Song, J. S. Park, S.-H. Jin, Y. I.
Kim, J.-J. Kim, Org. Electron. 2010, 11, 564–572; b) T. Sajoto,
P. I. Djurovich, A. B. Tamayo, J. Oxgaard, W. A. Goddard III,
M. E. Thompson, J. Am. Chem. Soc. 2009, 131, 9813–9822; c)
L. He, L. Duan, J. Qiao, R. Wang, P. Wei, L. Wang, Y. Qiu,
Adv. Funct. Mater. 2008, 18, 2123–2131; d) J. H. Seo, Y. K.
Kim, Y. Ha, Thin Solid Films 2009, 517, 1807–1810.
a) A. Caballero, R. Tormos, A. Espinosa, M. D. Velasco, A.
Tarraga, M. A. Miranda, P. Molina, Org. Lett. 2004, 6, 4599–
4602; b) F. Bolletta, A. Garelli, M. Montalti, L. Prodi, S. Rom-
ano, N. Zaccheroni, L. Canovese, G. Chessa, C. Santo, F. Vi-
sentin, Inorg. Chim. Acta 2004, 357, 4078–4084; c) H. Miyaji,
P. Anzenbacher Jr., J. L. Sessler, E. R. Bleasdaleb, P. A. Gale,
Chem. Commun. 1999, 1723–1724; d) G. Kaur, H. Fang, X.
Gao, H. Li, B. Wang, Tetrahedron 2006, 62, 1–8.
10-(4-{Bis[4Ј-(diphenylamino)biphenyl-4-yl]amino}phenyl)-10-(9,9-
dihexylfluoren-2-yl)anthracene (FATT): FATT (0.09 g, 54%) was
synthesized from 3 and [4-(diphenylamino)phenyl]boronic acid in
a manner similar to that for 2 and obtained as a yellow-green solid
[9]
(m.p. 148 °C). FTIR (KBr): ν = 2990, 2686, 2360, 1726, 1588, 1422,
˜
1
1266, 894 cm–1. H NMR (300 MHz, CDCl3): δ = 0.76–0.81 (m, 5
H), 1.11 (m, 6 H), 2.02 (m, 2 H), 7.02–7.07 (m, 2 H), 7.16 (d, J =
7.8 Hz, 6 H), 7.30 (d, J = 7.8 Hz, 4.5 H), 7.36–7.45 (7.5 H, m),
7.48–7.53 (2.5 H, m), 7.59 (d, J = 8.7 Hz, 2 H), 7.79–7.96 (m, 3 H)
ppm. 13C NMR (75 MHz, CDCl3): δ = 14.03, 22.51, 23.90, 29.67,
30.92, 31.56, 40.48, 55.27, 119.63, 119.80, 122.89, 124.08, 124.39,
124.80, 125.03, 126.18, 126.17, 126.90, 127.10, 127.38, 127.54,
129.28, 129.91, 130.13, 132.26, 134.68, 136.87, 137.65, 137.70,
140.56, 141.01, 146.88, 147.74, 150.88, 150.99 ppm. HRMS: calcd.
for C93H81N3 [MH+] 1240.6464; found 1241.6255.
[10]
[11]
[12]
[13]
Supporting Information (see footnote on the first page of this arti-
cle): Quantum chemical calculation results, multiple CV scans,
1
DSC/TGA thermograms, and H and 13C NMR spectra.
Acknowledgments
This work was financially supported by the SUT Research and De-
velopment Fund. We acknowledge the support from the Thailand
Research Fund (grant number RMU5080052), the Center of Excel-
lence for Innovation in Chemistry, the Strategic Scholarships for
Frontier Research Network for Research Groups (grant number
CHE-RES-RG50) from the Office of Higher Education Council,
and the Science Achievement Scholarship of Thailand (SAST).
[1] C. W. Tang, S. A. VanSlyke, Appl. Phys. Lett. 1987, 51, 913–
615.
[2] a) C.-C. Wu, C.-W. Chen, C.-L. Lin, C.-J. Yang, J. Disp. Tech-
nol. 2005, 1, 248–266; b) B. Geffroy, P. le Roy, C. Prat, Polym.
Int. 2006, 55, 572–682.
[14]
[15]
[3] F. So, J. Kido, P. L. Burrows, MRS Bull. 2008, 33, 663–669.
[4] A. W. Grice, D. D. C. Bradley, M. T. Bernius, M. Inbasekaran,
W. W. Wu , E . P. Wo o, Appl. Phys. Lett. 1998, 73, 629–631.
[5] a) A. M. Thangthong, N. Prachumrak, S. Namuangruk, S.
Jungsuttiwong, T. Keawin, T. Sudyoadsuk, V. Promarak, Eur.
J. Org. Chem. 2012, 27, 5263–5274; b) A. M. Thangthong, N.
Prachumrak, R. Tarsang, T. Keawin, S. Jungsuttiwong, T. Sud-
yoadsuk, V. Promarak, J. Mater. Chem. 2012, 22, 6869–6877;
c) Q.-X. Tong, S.-L. Lai, M.-Y. Chan, Y.-C. Zhou, H.-L.
Kwong, C.-S. Lee, S.-T. Lee, Chem. Mater. 2008, 20, 6310–
6312.
[6] a) K.-R. Wee, W.-S. Han, J.-E. Kim, A.-L. Kim, S. Kwon, S. O.
Kang, J. Mater. Chem. 2011, 21, 1115–1123; b) P.-I. Shih, C.-
Y. Chuang, C.-H. Chien, E. W.-G. Diau, C.-F. Shu, Adv. Funct.
Mater. 2007, 17, 3141–3146; c) S. Tao, Y. Zhou, C.-S. Lee, S.-
T. Lee, D. Huang, X. Zhang, J. Phys. Chem. C 2008, 112,
14603–14606; d) G. Zhang, G. Yang, S. Wang, Q. Chen, J. S.
Ma, Chem. Eur. J. 2007, 13, 3630–3635; e) J. Wang, W. Wan,
a) C. L. Chochos, G. K. Govaris, F. Kakali, P. Yiannoulis, J. K.
Kallitsis, Polymer 2005, 46, 4654–4663; b) G. KlaÈrner, M. H.
Davey, W. D. Chen, J. C. Scott, R. D. Miller, Adv. Mater. 1998,
10, 993–997; c) J. A. Mikroyannidis, Polymer 2000, 41, 8193–
8204.
T. J. Boyd, Y. Geerts, J.-K. Lee, D. E. Fogg, G. G. Lavoie, R. R.
Schrock, M. F. Rubner, Macromolecules 1997, 30, 3553–3559.
a) G. Kaur, H. Fang, X. Gao, H. Li, B. Wang, Tetrahedron
2006, 62, 1–8; b) F. Bolletta, A. Garelli, M. Montalti, L. Prodi,
S. Romano, N. Zaccheroni, L. Canovese, G. Chessa, C. Santo,
F. Visentin, Inorg. Chim. Acta 2004, 357, 4078–4084; c) A. Ca-
ballero, R. Tormos, A. Espinosa, M. D. Velasco, A. Tarraga,
M. A. Miranda, P. Molina, Org. Lett. 2004, 6, 4599–4602.
[16]
[17]
10
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Pages: 11
9-(Fluoren-2-yl)anthracene Derivatives
[18] a) D. Gebeyehu, K. Walzer, G. He, M. Pfeiffer, K. Leo, J.
Brandt, A. Gerhard, P. Stößel, H. Vestweber, Synth. Met. 2005,
148, 205–211; b) Z. L. Zhang, X. Y. Jiang, W. Q. Zhu, X. Y.
Zheng, Y. Z. Wu, S. H. Xu, Synth. Met. 2000, 137, 1141–1142;
c) S. W. Cha, S.-H. Choi, K. Kim, J.-I. Jin, J. Mater. Chem.
2003, 13, 1900–1904.
[19] A. M. Thangthong, D. Meunmart, N. Prachumrak, S. Jungsut-
tiwong, T. Keawin, T. Sudyoadsuk, V. Promarak, Chem. Com-
mun. 2011, 47, 7122–7124.
[20] a) V. Promarak, A. Pankvuang, S. Jungsuttiwong, S. Saengsu-
wan, T. Sudyoadsuk, T. Keawin, Tetrahedron Lett. 2007, 48,
3661–3665; b) V. Promarak, A. Pankvuang, S. Ruchirawat, Tet-
rahedron Lett. 2007, 48, 1151–1154.
[21] a) H. Xia, J. He, B. Xu, S. Wen, Y. Li, W. Tian, Tetrahedron
2008, 64, 5736–5742; b) Z. Q. Gao, Z. H. Li, P. F. Xia, M. S.
Wong, K. W. Cheah, C. H. Chen, Adv. Funct. Mater. 2007, 17,
3194–3199.
tin, K. Morokuma, V. G. Zakrzewski, G. A. Voth, P. Salvador,
J. J. Dannenberg, S. Dapprich, A. D. Daniels, Ö. Farkas, J. B.
Foresman, J. V. Ortiz, J. Cioslowski, and D. J. Fox, Gaussian 09,
Revision A.1, Gaussian, Inc., Wallingfordm, CT, 2009.
T. M. Swager, C. J. Gil, M. S. Wrighton, J. Phys. Chem. 1995,
99, 4886–4893.
K.-T. Wong, C.-F. Wang, C. H. Chou, Y. O. Su, G.-H. Lee, S.-
M. Peng, Org. Lett. 2002, 4, 4439–4442.
V. Promarak, A. Punkvuang, D. Meunmat, T. Sudyoadsuk, S.
Saengsuwan, T. Keawin, Tetrahedron Lett. 2007, 48, 919–923.
[23]
[24]
[25]
[26]
K. T. Kamtekar, C. Wang, S. Bettington, A. S. Batsanov, I. F.
Perepichka, M. R. Bryce, J. H. Ahn, M. Rabinal, M. C. Petty,
J. Mater. Chem. 2006, 16, 3823–3835.
[27]
U. Mitschke, P. Bäuerle, J. Mater. Chem. 2000, 10, 1471–1507.
[28] a) Q.-X. Tong, S.-L. Lai, M.-Y. Chan, K.-H. Lai, J.-X. Tang,
H.-L. Kwong, C.-S. Lee, S.-T. Lee, Chem. Mater. 2007, 19,
5851–5855; b) Y. K. Kim, S.-H. Hwang, Synth. Met. 2006, 156,
1028–1035; c) G. Giro, M. Cocchi, J. Kalinowski, V. Fattori,
P. D. Marco, P. Dembech, G. Seconi, Adv. Mater. Opt. Electron.
1999, 9, 189–194.
[22] 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. Son-
nenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hase-
gawa, M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai,
[29] V. Promarak, M. Ichikawa, T. Sudyoadsuk, S. Saengsuwan, S.
Jungsuttiwong, T. Keawin, Synth. Met. 2007, 157, 17–22.
T. Vreven, J. A. Montgomery Jr., J. E. Peralta, F. Ogliaro, M. [30] T. Kartens, K. Kobs, J. Phys. Chem. 1980, 84, 1871–1872.
Bearpark, J. J. Heyd, E. Brothers, K. N. Kudin, V. N. Starov-
erov, 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. Ad-
amo, J. Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev,
A. J. Austin, R. Cammi, C. Pomelli, J. W. Ochterski, R. L. Mar-
[31] S. R. Forrest, D. D. C. Bradley, M. E. Thomson, Adv. Mater.
2003, 15, 1043–1048.
[32] C. J. Kelley, A. Ghiorghis, J. M. Kauffman, J. Chem. Res. Mini-
print 1997, 2701–2709.
Received: January 30, 2013
Published Online: ᭿
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