Synthesis and electroluminescent properties of fluorene- and anthracene-derivatives containing novel tetraphenylbenzene moiety

Article abstract of DOI:10.1080/15421400490506126

2,7-Bis[(2,3,4,5-tetraphenyl)phenyl]-9,9-diethylfluorence(BTPDF) and 2,7-Bis [(2,3,4,5-tetraphenyl) phenyl]-9, 10-anthracene(BTPA), which consist of a diethylfluorene and an anthracene with two tetraphenylbenzene moieties, were synthesized by Diels-Alder

Full text of DOI:10.1080/15421400490506126

This article was downloaded by: [University of Waterloo]
On: 24 November 2014, At: 13:01
Publisher: Taylor & Francis
Informa Ltd Registered in England and Wales Registered Number: 1072954
Registered office: Mortimer House, 37-41 Mortimer Street, London W1T 3JH,
UK
Molecular Crystals and Liquid
Crystals
Publication details, including instructions for
authors and subscription information:
http://www.tandfonline.com/loi/gmcl20
Synthesis and
Electroluminescent Properties
of Fluorene- And Anthracene-
Derivatives Containing Novel
Tetraphenylbenzene Moiety
Kwang-Yol Kay a , Jung Kim a , Hyun Cho b & Jong-
Wook Park c
a Department of Molecular Science and Technology ,
Ajou University , Suwon, Korea
b Materials and Devices Research Center , KIST ,
Seoul, Korea
c Department of Chemistry/Center for
Nanotechnology Research , The Catholic University ,
Pucheon, Korea
Published online: 18 Oct 2010.
To cite this article: Kwang-Yol Kay , Jung Kim , Hyun Cho & Jong-Wook Park (2004)
Synthesis and Electroluminescent Properties of Fluorene- And Anthracene-Derivatives
Containing Novel Tetraphenylbenzene Moiety, Molecular Crystals and Liquid Crystals,
424:1, 167-172, DOI: 10.1080/15421400490506126
To link to this article: http://dx.doi.org/10.1080/15421400490506126
PLEASE SCROLL DOWN FOR ARTICLE
Taylor & Francis makes every effort to ensure the accuracy of all the
information (the “Content”) contained in the publications on our platform.
However, Taylor & Francis, our agents, and our licensors make no

representations or warranties whatsoever as to the accuracy, completeness,
or suitability for any purpose of the Content. Any opinions and views
expressed in this publication are the opinions and views of the authors, and
are not the views of or endorsed by Taylor & Francis. The accuracy of the
Content should not be relied upon and should be independently verified with
primary sources of information. Taylor and Francis shall not be liable for any
losses, actions, claims, proceedings, demands, costs, expenses, damages,
and other liabilities whatsoever or howsoever caused arising directly or
indirectly in connection with, in relation to or arising out of the use of the
Content.
This article may be used for research, teaching, and private study purposes.
Any substantial or systematic reproduction, redistribution, reselling, loan,
sub-licensing, systematic supply, or distribution in any form to anyone is
expressly forbidden. Terms & Conditions of access and use can be found at
http://www.tandfonline.com/page/terms-and-conditions

Mol. Cryst. Liq. Cryst., Vol. 424, pp. 167–172, 2004
Copyright # Taylor & Francis Inc.
ISSN: 1542-1406 print=1563-5287 online
DOI: 10.1080=15421400490506126
SYNTHESIS AND ELECTROLUMINESCENT
PROPERTIES OF FLUORENE- AND
ANTHRACENE-DERIVATIVES CONTAINING
NOVEL TETRAPHENYLBENZENE MOIETY
Kwang-Yol Kay and Jung Hoon Kim
Department of Molecular Science and Technology,
Ajou University, Suwon 442-749, Korea
Hyun Nam Cho
Materials and Devices Research Center,
KIST, Seoul 130-650, Korea
Jong-Wook Park
Department of Chemistry=Center for Nanotechnology Research,
The Catholic University, Pucheon 420-734, Korea
2,7-Bis[(2,3,4,5-tetraphenyl)phenyl]-9,9-diethylfluorene(BTPDF) and 2,7-Bis
[(2,3,4,5-tetraphenyl)phenyl]-9,10-anthracene(BTPA), which consist of a
diethylfluorene and an anthracene with two tetraphenylbenzene moieties,
were synthesized by Diels-Alder reaction and characterized to investigate elec-
troluminescent(EL) behavior.
BTPDF and BTPA showed violet and blue PL spectra at 400 nm and
˚
˚
˚
456 nm. The device of m-MTDATA(600 A)=NPB(150 A)=BTPDF or BTPA(300 A)=
˚
Alq3(300 A)=LiF(10 A)=Al(2000 A) showed turn-on voltage of 9 V and 13 V and
˚
˚
blue and green EL spectrum at 466 nm and 504 nm, respectively.
Keywords: anthracene; electroluminescence; fluorene; highly phenyl substituted molecules
Received 1 October 2003; accepted 5 February 2004.
The author (K. Y. K.) wishes to acknowledge the financial support from BK21 project in 2003,
and this work was supported by grant No. R01-2002-000-00347-0 from the interdisciplinary
research program of the KOSEF.
Address correspondence to Jong-Wook Park, Department of Chemistry=Center
for Nanotechnology Research, The Catholic University, Pucheon 420-734, Korea. Tel.:
þ82-32-340-3821, Fax: þ82-32-340-3764, E-Mail: hahapark@catholic.ac.kr
167

168
K.-Y. Kay et al.
1. INTRODUCTION
Organic light-emitting devices(OLEDs) have attracted a great attention
due to their promising applications in electroluminescent displays since
the first report of efficient emission from amorphous molecular materials
by Tang and VanSlyke [1–3]. Thereafter, considerable efforts have been
focused on obtaining amorphous glassy materials with high EL efficiency,
which have stable nonplanar molecular structures bearing bulky and heavy
substituents such as polyphenylene [4,5] or triarylamine [6] moieties. In line
with these aspects we report here the first synthesis and characterization
of 2,7-bis[(2,3,4,5-tetraphenyl)phenyl]-9,9-dioctylfluorene(BTPDF, 1) and
2,7-bis[(2,3,4,5-tetraphenyl)phenyl]-9,10-anthracene (BTPA, 2) having
highly phenyl-substituted benzene moieties through Diels-Alder reaction.
Diels-Alder reaction for synthesis of OLEDs material could be expected
to have several merits such as highly pure material and high yield because
of no catalyst reaction.
2. EXPERIMENTS
Synthesis of BTPDF, 1 was described in Scheme 1.
SCHEME 1 Synthesis of BTPDF(1) and BTPA(2).

Fluorene- and Anthracene-derivatives
169
2.1. 2,7-Bis[(2,3,4,5-tetraphenyl)phenyl]-9,9-diethylfluorene
(BTPDF) (1)
To a solution of 2.7-diacetyl-9,9- diethylfluorene (1.01 g, 3.74 mmol) in
o-xylene (150 ml), tetraphenyl-2,4-cyclopentadiene-1-one(4.13 g, 10.74 mmol)
was added. The mixture was refluxed under nitrogen atmosphere for 3 d.
After cooled to 80ꢀC, the mixture was added to MeOH (200 ml) to give
yellow solids. The crude products were filtered and recrystallized from
MeOH=CH2Cl2 (1:1) to afford a solid product(1.63 g, 49.3%) (m.p. 96–98ꢀC).
1H-NMR(CDCl3, 400 MHz): d ¼ 7.70 ꢁ 6.70 (m, 48H, Ar-H), 1.50 (q, 4H,
CH2), 0.80 (t, 6H, CH3). FT-IR(KBr): 3054, 2962, 2917 cmꢁ1.
2.2. 2,7-Bis[(2,3,4,5-tetraphenyl)phenyl]-9,10-anthracene
(BTPA) (2)
BTPA was synthesized by same synthetic procedure as BTPDF’s (0.92 g,
1
25.0%). H-NMR (CDCl3, 400 MHz) d ¼ 7.81 ꢂ 6.40 (m, 50H, Ar-H). FT-
IR (KBr): 3020, 2925 cmꢁ1. MS(MALDI-TOF): 938(Mþ), 523(base peak).
3. RESULT AND DISCUSSION
Figures 1 and 2 show the UV-absorption and photoluminescence (PL)
spectra of the two emission layers in thin films on quartz plates. The
maximum absorption of BTPDF(1) appeared at 328 nm, and the absorption
edge of BTPDF(1) at 367 nm. For BTPA(2), the maximum absorption
appeared at 408 nm and the absorption edges at 426 nm.
FIGURE 1 UV-Visible spectrum and PL spectrum of BTPDF (excitation wave-
length ¼ 328 nm).

170
K.-Y. Kay et al.
FIGURE 2 UV-Visible spectrum and PL spectrum of BTPA (excitation wave-
length ¼ 408 nm).
The energy band gap of BTPDF and BTPA was 3.50 eV and 2.97 eV
according to UV absorption edge calculation, a plot of (hv) vs. (ahv)2.
Also, BTPDF and BTPA showed violet and blue PL spectra at 400 nm
and 456 nm, respectively. This PL difference might be due to the different
interaction between highly phenylated moieties and fluorene moiety and
anthracene moiety. More studies on aggregation effect of thin films by
through PL experiments are underway.
We measured I-V-L characteristics and EL spectrum of related EL
devices. The device structure was ITO 150 nm=m-MTDATA 60 nm=a-NPD
15 nm=BTPDF or BTPA 30 nm=Alq3 30 nm=LiF 1 nm=Al 200 nm.
Figure 3 shows forward-biased current-voltage(I–V) intensity curves for
the undoped organic EL device. These curves were obtained when the
devices were operated in a continuous direct current (dc) mode under for-
ward bias (positive voltage applied to the ITO contact). These devices exhi-
bit diode characteristics, that is, forward current increases with increasing
forward bias voltage. The turn-on voltages of BTPA and BTPDF devices are
about 9 V and 13 V, respectively.
Figure 4 shows the EL spectra of BTPDF and BTPA devices. BTPA
device showed real blue EL spectrum at 466 nm and BTPDF showed green
EL spectrum at 504 nm which might be originated from Alq3 layer or inter-
face layer between BTPDF and Alq3. It could be due to electron and hole
recombination at Alq3 layer or excimer or electroplex emission between
BTPDF and Alq3. For making recombination at BTPA inside layer, the
thickness of Alq3 layer could be decreased or the thickness of BTPA layer
could be increased much more. Further studies of EL property are under-
way. We summarized EL properties in Table 1.

Fluorene- and Anthracene-derivatives
171
FIGURE 3 Current-voltage(I–V) characteristics of BTPDF and BTPA devices.
FIGURE 4 EL spectra of devices using BTPDF and BTPA as an emissive layer.
TABLE 1 Luminescent Properties of the Device (at 10 mA=cm2) using BTPDF(1)
and BTPA(2) as an Emitting Layer
CIE coordinate
Emitting
material
EL peak
[nm]
Efficiency [lm=W]
@ 120 cd=m2
Efficiency
[cd=A]
Voltage [V]
@ 120 cd=m2
x
y
BTPDF
BTPA
504
466
0.18
0.37
0.82
1.10
13.7
9.30
0.248
0.190
0.384
0.283

172
K.-Y. Kay et al.
BTPDF and BTPA devices showed 0.82 cd=A and 1.10 cd=A with the CIE
chromaticity coordinates of (0.248, 0.384) and (0.190, 0.283), respectively.
REFERENCES
[1] Tang, C. W. & Van Slyke, S. A. (1987). Appl. Phys. Lett., 51, 913.
[2] Bulovic, V., Gu, G., Burrows, P. E., & Forrest, S. R. (1996). Nature, 380, 29.
[3] Adachi, C., Tsutsui, T., & Saito, S. (1990). Appl. Phys. Lett., 56, 799.
[4] Weil, T., Reuther, E., & Mu¨llen, K. (2002). Angew. Chem. Int. Ed., 41, 1900.
[5] Imai, M. & Arai, T. (2002). Tetrahedron Lett., 43, 5265.
[6] Shirota, Y. (2000). J. Mater. Chem., 10, 1.