Synthesis and property of new propeller shaped emitting materials for organic light-emitting devices

Article abstract of DOI:10.1166/jnn.2016.11055

New propeller type emitting compound, namely 3,6-di-anthracen-9-yl-9,10-bis-(4-anthracen- 9-yl-phenyl)-phenanthrene[TAnDAP] and 3,6-bis-(10-phenyl-anthracen-9-yl)-9,10-bis-[4-(10-phenylanthracen- 9-yl)-phenyl]-phenanthrene [TAnPDAP] were synthesized through Suzuki and McMurry reactions. We investigated their physical properties such as optical, electrochemical, and electroluminescent properties. The two compounds were used as an emitting layer in OLED devices: ITO/2-TNATA (60 nm)/NPB (15 nm)/non-doped: TAnDAP or TAnPDAP (35 nm)/Alq3 (20 nm)/LiF (1 nm)/Al (200 nm). The TAnDAP OLED device showed C.I.E. value of (0.28, 0.41) and luminance efficiency of 3.81 cd/A at 10 mA/cm². The TAnPDAP device showed C.I.E. value of (0.20, 0.27) and high luminance efficiency of 5.40 cd/A at 10 mA/cm². TAnPDAP was found to show better luminance efficiency and C.I.E. value than TAnDAP because it has a bulky 9-phenylanthracene.

Full text of DOI:10.1166/jnn.2016.11055

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Nanoscience and Nanotechnology
Vol. 16, 3102–3105, 2016
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Synthesis and Property of New Propeller Shaped
Emitting Materials for Organic Light-Emitting Devices
Seokwoo Kang1, Hayoon Lee1, Beomjin Kim1, Youngil Park2, and Jongwook Park1ꢀ∗
1Department of Chemistry, The Catholic University of Korea, Bucheon, 420-743, Korea
2Division of Ulsan Research and Business Development Research Center for Green Fine Chemicals,
Korea Research Institute of Chemical Technology, Ulsan, 681-802, Republic of Korea
New propeller type emitting compound, namely 3,6-di-anthracen-9-yl-9,10-bis-(4-anthracen-
9-yl-phenyl)-phenanthrene[TAnDAP] and 3,6-bis-(10-phenyl-anthracen-9-yl)-9,10-bis-[4-(10-phenyl-
anthracen-9-yl)-phenyl]-phenanthrene [TAnPDAP] were synthesized through Suzuki and McMurry
reactions. We investigated their physical properties such as optical, electrochemical, and electro-
luminescent properties. The two compounds were used as an emitting layer in OLED devices:
ITO/2-TNATA (60 nm)/NPB (15 nm)/non-doped: TAnDAP or TAnPDAP (35 nm)/Alq3 (20 nm)/LiF
(1 nm)/Al (200 nm). The TAnDAP OLED device showed C.I.E. value of (0.28, 0.41) and luminance
efficiency of 3.81 cd/A at 10 mA/cm2. The TAnPDAP device showed C.I.E. value of (0.20, 0.27)
and high luminance efficiency of 5.40 cd/A at 10 mA/cm2. TAnPDAP was found to show better
luminance efficiency and C.I.E. value than TAnDAP because it has a bulky 9-phenylanthracene.
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Keywords: OLEDs, Propeller Shaped Emitting Materials.
Copyright: American Scientific Publishers
1. INTRODUCTION
In our work, we tried to synthesize new propeller shaped
emitting materials with phenanthrene and anthracene moi-
eties. Chemical structure of propeller shaped emitting
materials is fully substituted by chromophore compound
and can provide highly thermal property.
Organic light-emitting devices (OLEDs) have attracted
much attention due to their potential applications in
flat-panel displays since the pioneer work of Tang and
VanSlyke. A full-color capability is required in flat-panel
display applications, especially white; the applications not
only include backlight sources of liquid crystal displays
(LCDs), but also candidates for next generation lighting.1–3
In order to make full color OLED display, we need red,
green and blue materials with high performance and high
EL efficiency, pure color coordinate (C.I.E.) value and long
life time, as well as material thermal property. Host and
dopant methods in fluorescence and phosphorescence sys-
tems have been used to get efficiency of OLED, and red
and green emitters have been developed and improved to
commercialize full color OLED However, a lot of prob-
lems still remains to be solved, for example blue emit-
ting material, device lifetime and luminous efficiency, etc.
Many kinds of blue materials including diarylanthracene,
di(styryl)arylene, fluorene and pyrene have been inten-
sively used and studied on improved EL property.4ꢀ5
2. EXPERIMENTAL DETAILS
2.1. Synthesis
The structures and synthetic routes of compounds are
shown in Scheme 1.
Compounds 1 ∼ 7 were synthesized according to the
literature.6ꢀ7
2.1.1. Synthesis of 3,6-Di-Anthracen-9-yl-9,10-Bis-
(4-anthracen-9-yl-phenyl)-Phenanthrene
(TAnDAP)
Compound 3 (2 g, 3.09 mmol), compound 4 (4.12 g,
18.5 mmol), triphenylphosphine (0.32 g, 1.23 mmol), and
Pd(OAc)2 (0.06 g, 0.31 mmol) were added in a 3-neck
round bottom flask, and 120 mL of anhydrous toluene
and 20 mL of anhydrous ethanol were sequentially added.
ꢀ
11 mL of 2M potassium carbonate was added at 60 C.
ꢀ
∗Author to whom correspondence should be addressed.
The solution was stirred for 1 day at 130 C. TLC was
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J. Nanosci. Nanotechnol. 2016, Vol. 16, No. 3
1533-4880/2016/16/3102/004
doi:10.1166/jnn.2016.11055

Kang et al.
Synthesis and Property of New Propeller Shaped Emitting Materials for OLEDs
Scheme 1. Synthetic routes of new compounds.
taken under chloroform:hexane= 1:3 condition to examine
TLC was taken under chloroform:hexane = 1:3 condition
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the progress of reaction. After completion of reaction, the to examine the progress of reaction. After completion of
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solution was extracted using chloroform and H2O. Small
reaction, the solution was extracted using chloroform and
H2O. Small amount of H2O remaining in the chloroform
layer was removed using MgSO4. After obtaining solid
by evaporation of product in the chloroform layer, column
refinement was performed under chloroform:hexane = 1:3
condition. The product obtained by column was dissolved
in small amount of chloroform and re-precipitated using
methanol before filtering. 0.12 g of yellow solid (4.8%
yield) was obtained by evaporating the filtered solid.
1H NMR (300 MHz, THF):ꢁ(ppm) 9.04(s, 2H),
8.44–8.41(d, 2H), 8.00–7.97(d, 2H), 7.92–7.87(t, 6H),
7.82–7.80(d, 4H), 7.72–7.53(m, 26H), 7.51–7.49(d, 6H),
7.48–7.43(t, 2H), 7.42–7.40(d, 4H), 7.39–7.28(m, 8H),
7.09–6.96(t, 2H), 6.53–6.51(t, 2H)
amount of H2O remaining in the chloroform layer was
removed using MgSO4. After obtaining solid by evapora-
tion of product in the chloroform layer, column refinement
was performed under chloroform:hexane= 1:3 condition.
The product obtained by column was dissolved in small
amount of chloroform and re-precipitated using methanol
before filtering. 0.12 g of yellow solid (3.7% yield) was
obtained by evaporating the filtered solid.
1H NMR (300 MHz, THF):ꢁ(ppm) 8.98(s, 2H),
8.55–8.53(d, 4H), 8.36–8.34(d, 2H), 8.10–8.08(d, 2H),
8.05–8.02(d, 4H), 7.97–7.93(t, 4H), 7.86–7.72(m, 10H),
7.59–7.53(d, 4H), 7.50–7.45(t, 4H), 7.44–7.41(t, 6H),
7.38–7.27(t, 4H), 7.10–7.05(t, 2H), 6.49–6.46(t, 2H)
MS (MALDI-TOF): 1035.27 (m/z), calcd. for C82 H50:
1035.4016.
MS (MALDI-TOF): 1339.66 (m/z), calcd. for C106
H66: 1339.5198
2.2. Synthesis of 3,6-Bis-(10-phenyl-anthracen-9-yl)-
9,10-Bis-[4-(10-phenyl-anthracen-9-yl)-phenyl]-
Phenanthrene (TAnPDAP)
2.3. Measurements
The optical absorption spectra were obtained by HP
8453 UV-VIS-NIR spectrometer. Perkin Elmer lumines-
cence spectrometer LS50 (Xenon flash tube) was used for
photo-luminescence (PL) spectroscopy. Thermal degrada-
tion temperature (Td) of the compounds was measured by
thermo-gravimetric analysis (TGA) using SDP-TGA2960
(TA instrument). The redox potential of the synthesized
materials was measured at the scanning rate of 50 mV/s
by WBCS 3000 system with cyclic voltammeter (CV).
Compound 3 (1 g, 1.54 mmol), compound 7 (2.77 g,
9.28 mmol), triphenylphosphine (0.16 g, 1.23 mmol), and
Pd(OAc)2 (0.034 g, 0.15 mmol) were added in a 3-neck
round bottom flask, and 60 mL of anhydrous toluene and
10 mL of anhydrous ethanol were added under nitrogen
condition. 5.4 mL of 2M potassium carbonate was added
ꢀ
ꢀ
at 60 C. The solution was stirred for 1 day at 130 C.
J. Nanosci. Nanotechnol. 16, 3102–3105, 2016
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Synthesis and Property of New Propeller Shaped Emitting Materials for OLEDs
Kang et al.
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I–V –L characteristic of non-doped OLED device,
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(b) Normailized EL spectra of TAnDAP or TAnPDAP OLED device:
ITO/2-TNATA (60 nm)/NPB (15 nm)/non-doped EML: TAnDAP or
TAnPDAP (35 nm)/Alq3 (20 nm)/LiF/Al.
Figure 1. (a) UV and PL of TAnDAP and TAnPDAP in solution state
(Chloroform 10−5 M), (b) UV and PL of TAnDAP and TAnPDAP in film
state.
3. RESULTS AND DISCUSSION
Table I. Optical property of TAnDAP, TAnPDAP.
TAnDAP and TAnPDAP were synthesized as new pro-
peller shaped emitting materials. The optical properties of
the synthesized compounds are summarized in Table I. As
a result of synthesizing TAnDAP and TAnPDAP, PL wave-
length region in solution state showed a sharp band in blue
region of 421, 433 nm (Fig. 1).
Solutiona
Film
UVmax
(nm)
PLmax
(nm)
UVmax
(nm)
PLmax
(nm)
Compounds
TAnDAP
TAnPDAP
351, 369, 389
359, 378, 398
421
433
356, 374, 394
361, 379, 399
464, 504
458, 513
In film state, excimer peak of the two compounds was
observed with greater red shift of PL wavelength due to
intermolecular packing. However, excimer peak in film
state PL was reduced in TAnPDAP compared to TAn-
DAP. (Fig. 1(b)) Excimer was reduced by substitution
of 9-phenylanthracene, which is bulkier than anthracene
in same position. This implies that excimer can be pre-
vented by substitution of bulkier group.8ꢀ9 As a result
Note: aChloroform, 10−5 M.
The current–voltage-luminance (I–V –L) characteristics of
the fabricated EL devices were obtained by Keithley 2400
electrometer, and light intensity was obtained by Minolta
CS-1000A.
Table II. EL performances of multilayered devices with the synthesized compounds at 10 mA/cm2 and the optical, electrical and thermal properties
of the synthesized materials.
Emitting
materials
Volta
(V)
C.E.b
(cd/A)
P.E.c
(lm/W)
C.I.Ed
(x, y)
ELmax
(nm)
HOMO
(eV)
LUMO
(eV)
Ege
Tdf
(ꢀC)
(eV)
TAnDAP
TAnPDAP
8.11
8.54
3.81
5.40
1.62
2.19
0.28, 0.41
0.20, 0.27
504
466
5.29
5.26
2.31
2.30
2.98
2.96
455
540
Notes: aVolt: turn on voltage, bC.E.: current efficiency, cP.E: power efficiency, dCIE: Commission Internationale de l’Eclairage, eEg (band gap) calculated from the optical
absorption edge f TGA at a heating rate of 10 ꢀC/min.
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J. Nanosci. Nanotechnol. 16, 3102–3105, 2016

Kang et al.
Synthesis and Property of New Propeller Shaped Emitting Materials for OLEDs
of examining thermal property, TAnPDAP showed higher
Td value due to more rigid structure, as well as higher
molecular weight. (Table II) An EL device of ITO/2-
TNATA (60 nm)/NPB (15 nm)/non-doped EML:TAnDAP
or TAnPDAP (35 nm)/Alq3 (20 nm)/LiF/Al was fabricated.
Table II and Figure 2 show EL performance and electrical
property. TAnDAP and TAnPDAP had current efficiency
of 3.81 and 5.40 cd/A, and power efficiency of 1.62 and
2.19 lm/W, respectively. This might be due to the effect
of greater fluorescent quantum efficiency in the substituted
9-phenylanthracene (ꢂf = 0ꢃ41) compared to anthracene
(ꢂf = 0ꢃ27) on EL performance. Also, molecular packing
induces excimer and decreased EL efficiency in film state.
9-phenylanthracene was introduced to prevent this pack-
ing in this chemical structure compared to just anthracene
group.8ꢀ9 As a result, propeller structure which is non-
planner type can also improve EL performance because it
efficiently prevents intermolecular packing in film state.10
C.I.E (x, y) value was (0.28, 0.41) for TAnDAP and (0.20,
0.27) for TAnPDAP.
and TAnPDAP was observed in deep blue region, further
studies on these compounds as dopants in EL device are
underway.
Acknowledgment: This work was supported by
the National Research Foundation of Korea (NRF)
grant funded by the Korean government (MEST)
(No. 2012001846). This research was supported by a grant
from Global Collaborative R&D Project by the Ministry
of Trade, Industry and Energy (The Korea Institute for the
Advancement of Technology) (No. N0000903).
References and Notes
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The TAnDAP device showed C.I.E. value of (0.28, 0.41)
and luminance efficiency of 3.81 cd/A at 10 mA/cm2. TAn-
PDAP also exhibited high luminance efficiency of 5.40
cd/A at 10 mA/cm2 and C.I.E. value of (0.20, 0.27). It
was found that TAnPDAP shows better luminance effi-
ciency and C.I.E. value than TAnDAP. EL performance
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of TAnPDAP is better not only because the substituted
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9-phenylanthracene has higher fluore-scent quantum effi-
ciency than anthracene but also because it is a bulkier
moiety. Since solution PL wavelength of both TAnDAP
Received: 17 June 2014. Accepted: 1 September 2014.
J. Nanosci. Nanotechnol. 16, 3102–3105, 2016
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