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A New [5] Helicene Derivative as Novel Emissive Material for Organic Light-Emitting Diode
Siriporn Kamtonwong , Somboon Sahasithiwat , Waraporn Panchan, Laongdao Menbangpung, and Thanasat Sooksimuang
National Metal and Materials Technology Center (MTEC) , Thailand
Pure and Applied Chemistry International Conference 2013
The Tide Resort, January 25, 2013
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Outline
Introduction
Experimental
Results and discussion
Conclusion
Light
+
3
Basic for light generation via OLED
OLED Device Operation Principle
Introduction
LightCathode
Anode
ETL
HTLHole +
++
--
-
EML
Excitation
-+
OLED Structure
Cathode
EML/ETL
HTL
Anode
Substrate
-
4
Helicenes
[5] Helicene [6] Helicene [7] Helicene
Under UVDDH in CHCl3
S. Sahasithiwat, T. Mophuang, L. Menbangpung, S. Kamtonwong and T. Sooksimuang.Synthetic Metals 160(2010)1148-1152.
DDH in CHCl3: Φf = 0.27
Φf = 0.02-0.04
3,12-Dimethoxy-7,8-dicyano-[5]helicene (DDH)
MeO
MeO
CN
CN
2
9
3
4 56
8
1011
12
141 7
13
Electrondonating
Electronwithdrawing
5
3,12-Dimethoxy-[i]furan-1,3-diono-[5]helicene (DFH)
MeO
MeO
O
O
O
as novel Emissive Material for Organic light-Emitting Diode
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Experimental
7
Preparation of DFH
DDQ, xylene
reflux
MeO
MeO MeO
MeO
O
O
O
O
O
O
MeO
MeO
O
O
OMeO
MeO
O
O
O
+
NBS
DFH
1 2
3
70-80%
75%
70%
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OLED fabrication
Configuration:
Glass
ITO
PEDOT:PSS
DFH
Ca/Al
J-V-L CharacteristicsMeasured
ITO/PEDOT:PSS(35nm)/DFH/Ca(10nm)/Al(100nm)
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Results and discussions
250 300 350 400 450 500 550 600 650 700 7500.0
0.2
0.4
0.6
0.8
1.0
Wavelength (nm)
Norm
aliz
ed A
bso
rban
ce
0.0
0.2
0.4
0.6
0.8
1.0
451437
340
535
Flu
ore
scen
ce In
tensi
ty
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UV in CHCl3, λmax : 340, 437, 451 nm
PL, λmax : 535 nm
Φf = 0.13
Normalized UV/Vis absorption and fluorescence spectra of DFH in dilute (3x10-6 M) CHCl3 solution.
FWHM : 78 nm
The optical properties of DFH
Under UV
MeO
MeO
O
O
O
DFH in dilute CHCl3 solution.
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Thermal properties of DFH
DSC: Tm 315 oC
TGA: Td,5 360 oC
MeO
MeO
O
O
O
50 100 150 200 250 300 350
Endoth
erm
al
Temperature (oC)
DSC thermogram of DFH TGA thermogram of DFH
100 200 300 400 500 600 700 800 900 10000
10
20
30
40
50
60
70
80
90
100
Wei
ght (%
)
Temperature (oC)
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Energy levels of DFH
Cyclic voltammetric technique
Cyclic voltammogram of DFH in 0.1 M Bu4NBF4 in acetonitrile solution performed in a three-electrode cell (a glassy carbon working, a platinum counter and a Ag/Ag+,0.1 M AgNO3, non-aqueous reference electrode) at a scan rate of 50 mV/s.
HOMO: Ip = -(E'ox + 4.4) eV (1)
LUMO: Ea= -(E‘red + 4.4) eV (2)
MeO
MeO
O
O
O
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Structure of the OLED
HIL
EML
Anode
Cathode
h+
e-
ITO
PEDOT:PSS
DFH
Ca(10 nm)/Al (100 nm)
Glass
Light
Structure and energy level diagram of the OLED
Energy level diagram
ITO/PEDOT:PSS(35nm)/DFH/Ca(10nm)/Al(100nm)
Vacuum Level
ITO PEDOT:PSS DFH Ca
-4.9 eV-5.2 eV
-5.9 eV
-3.6 eV
-2.8 eV
LUMO
HOMO
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Plots of current density-voltage-brightness characteristicof ITO/PEDOT:PSS/DFH(80 nm)/Ca/Al device
Current density-voltage-brightness characteristics of the OLED
ITO/PEDOT:PSS(35nm)/DFH/Ca(10nm)/Al(100nm)
ILV Characteristic of OLED with DFH
(0.41,0.55)-(0.46,0.52)
CIE Coordinate15
DFH
thickness
(nm)
Turn on voltage
(V)
Current Eff.
(cd/A)
Power Eff.
(lm/W)
Max.
Brightness (cd/m2)
CIE
Coordinate
(x,y)
60 3.4 0.16 0.09 696 (0.44,0.58)-(0.46,0.54)
80 4.9 0.33 0.15 881 (0.41,0.55)-(0.46,0.52)
100 4.4 0.30 0.13 760 (0.44,0.53)-(0.47,0.52)
ITO/PEDOT:PSS(35nm)/DFH/Ca(10nm)/Al(100nm)
increasing applied voltage
OLED
Excimer formation
Green yellow
5.5 V 6.5 V 8.5 V
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Conclusion
MeO
MeO
O
O
O
DFH
Easy to synthesized with good yield
Good thermal stability
Excellent optical properties
DFH was successfully utilized as a new emitter for OLED.
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National Metal and Materials Technology Center (MTEC)
Acknowledgments
National Science and Technology Development Agency(NSTDA)
Ministry of Science and Technology (MOST), Thailand
under grant number MT-B-55-POL-07-523-I
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Thank you for your kind attention
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LUMO LUMO
HOMO HOMO
Donormolecule
Acceptormolecule
Excimeremission
Excitedmonomer
Excimer
Monomeremission
Excimeremission
Ground State
Energy
High
Low
The formation of excimer in organic molecule
Light emission from excimer is red shiftedfrom the excited monomer
Excimer: a single excited molecule can interact with an unexcited neighbor to produce the excited dimer, or excimer
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+
Cathode
Anode
EILETL
EML
ExcitationHIL
HTL+
++
+
--
--
Hole
-
Light
Fig. Basis for light generation via OLED
Cathode
EIL
ETL
EML
HTL
HIL
Anode
Light
The multi-layered device
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OLED fabrication
ITO/PEDOT:PSS/DFH/Ca/Al Configuration:
ITO coated-glass slide was cleaned.
PEDOT:PSS was spin-coated onto ITO substrate.
then it was baked at 140 oC for 10 min.
DFH was deposited by thermal evaporation
onto the PEDOT:PSS coated substrate.
Calcium was evaporated onto the organic layer.
Aluminum was coated onto calcium layer.
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NMR
MeO
MeO
O
O
O
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FT-IR spectrum
MeO
MeO
O
O
O
1827, 1762
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Helical structure
Enantiomers
(M) [5] Helicene (P) [5] Helicene
Clockwise helix Anticlockwise helix
3,12-Dimethoxy-7,8-dicyano-[5]helicene (DDH)
UV 365 nm
DDH in CH2Cl2
under
MeO
MeO
CN
CN
S. Sahasithiwat, T. Sooksimuang, T. Mophuang, L. Menbangpung and S. Kamtonwong Synthetic Metals 160(2010)1148-1152
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Fig. 3. OLED Research
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H3CO OCH3
OO O
1
23
4
5
67 8
9
10
1112
1314H3CO OCH3
OO O
1
23
4
5
67 8
9
10
1112
1314
Vacuum Level
ITO PEDOT:PSS DFH Ca
-4.9 eV-5.2 eV
-5.9 eV
-3.6 eV
-2.8 eV
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