1. University Malaya
Woon Kai Lin1, Yeo Keat Hoe1, Thomas J Whitcher1, Noor Azrina Talik1, Calvin Ng1 ,Wang Seng Wong1
Zainal A. Hasan2, Bee Kian Ong2, Azhar Ariffin2, Show-An Chen3, Raimonda Griniene4, Saulius
Grigalevicius4 ,Narong Chanlek4, Hideki Nakajima5, Thainit Saisopa5, Prayoon Songsiriritthigul5, Yap Boon Kar6
1. Physics Department, University of Malaya
2. Chemistry Department, University of Malaya
3. Chemical Engineering Department, National Tsing Hua University, Taiwan
4. Department of Polymer Chemistry and Technology, Kaunas University of Technology, Lithuania
5. Thailand Synchrotron Light Source, Thailand
6. University Tenaga Nasional, College of Engineering
1
High efficiency Solution Processable Organic Light
Emitting Diode Through Materials and Interfacial
Engineering

2. OLED: A Brief Review
4

3. What is a good organic LED
Stability
(eg outdoor, indoor ,
Portable in/outdoor)
Cost
(cheap
manufacturing,
Initial cost of
investment?)
Efficiency
( lm/W, cd/A)
Functionality
(eg transparency, flexibility
Aesthetic, ease of integration)
OLED
Technology
Product

4. Example of OLED Applications
5
Artistic OLED lighting OLED TV
Identification Security
Flexible OLED for Cloud Computing
Foldable OLED for cloud
computing
Gadget, Internet of
Things, smart watch
Medical OLED lights for
cancer cells killing.
OLED Data Glass
Medical OLED
BMW car light
Internet
Interconnectedness

5. OLED Development Paradigms
5

6. OLED Efficiency
5
Quantum efficiency increased significantly
When efforts are taken to overcome the
1. Light trapped in the substrate
2. Waveguide loss
3. Surface plasmons
etc…
Focus on the device
level only
EQE max ~ 15%

7. OLED Problem Statements
5
• Limited number of ways to increase device
efficiency of existing materials. (Problem A)
• Material synthesis is often done by trials and
errors.(Problem B)
• Limited number of solution processable materials
for the blue host.(Problem C)

8. Proposed Study
5
• Limited number of ways to increase device efficiency of existing
materials.
Study of interfacial Physics. Multilayer OLED by solution process.
• Limited number of solution processable materials for the blue.
Synthesizing new materials
• Material synthesis is often done by trials and errors.
Leverage on increasing computational power. Do simulation
study

9. Device Methodology
5
Encapsulation
Add connection legs
for IVL test
Al cathode deposition
using thermal
evaporator
Spin coat
PEDOT:PSS as
hole transporting
layer
Spin coat organic
layer

10. In the presentation slide,
I will group the level of
technology readiness
from our research group.
Role of university
Role of start-
up and
industry

11. Efficiency enhancement of a solution processed single layer blue
PHOLED using Triton X-100TRL-4
For high efficiency OLED, the host must have
higher triplet energy than the emitter to avoid
energy back transfer.
Triton
X-100
concentr
ation
(wt%)
VON
(1cd/m2
)
1VON
1PE
(lm/W)
1CE
(cd/A)
2VON
2PE
(lm/
W)
2CE
(cd/A)
0 4.6 6.7 3.9 8.4 8.5 4.9 13.4
0.8 4.5 6.4 4.4 9.2 8.2 5.7 14.7
3.2 3.5 5.6 7.0 12.7 7.3 8.5 20.1
10 4.2 5.9 5.7 6.9 7.3 7.6 16.5
Featured as a cover page
1At brightness of 100 cd/m2
2At brightness of 1000 cd /m2
K.H. Yeoh, C.L. Chua, K.L. Woon
Synthetic Metals 172,44 (2013)

12. Multi layer blue phosphorescent OLED
(a)
11 lm/W
(0.16,0.38)
(b)
TRL-4
Keat Hoe Yeoh, Calvin Yi Bin Ng, Chong Lim Chua, Noor
AzrinaTalik, and Kai Lin Woon, Phys. Status Solidi Rapid
Research Letters , 1–4 (2013)

13. Energy Barrier
Thomas Whitcher; Wong Wah Seng; Talik Noor Azrina; Woon Kai
,Chanlek, Narong; Nakajima Hideki; Saisopa Thanit;
Songsiriritthigul Prayoon, J. Phys. D: Appl. Phys. 49 (2016)
325106
TRL-3
Gaussian disorder is a measure of positional
and energy disorder of organic materials.
Crystal has small disorder.
Fermi-pinning is non-existent for all of the
DOS widths simulated if we use polymer
conducting electrodes
Fermi-level pinning is something that occurs at metal-semiconductor interfaces. It creates
an energy barrier for electrons and holes by bending the bands at the interface.It degrades
performance radically in devices because it's a parasitic resistance that burns energy while
doing nothing useful.
Energybarrier
Work Function of electrode
Energybarrier
Decrease barrier
with decreasing
disorder
Work Function of polymeric electrode
ITO
Fermi pinning
Near zero
barrier
Decrease barrier
with decreasing
disorder
High work-
function is
GOOD

14. Energy Level MatchingTRL-4
Blue phosphorescent host often has a deeper HOMO level. By using self-organizing
Nafion doped Pedot:Pss, the work function of PEDOT:PSS can match with the host.
Increase hole
injection
Optimized blue device efficiency (Device III) improves from 7.3
lmW-1 (15.4 cd/A) and 5.9 lmW-1 (16.5 cd/A) to 9.4 lmW-1
(18.2 cd/A) and 7.9 lmW-1 (20.4 cd/A) at 100 cdm-2 and 1000
cdm-2 respectively.
Keat Hoe Yeo,Noor Azrina Talik, Thomas Whitcher, Calvin Ng, Kai Lin Woon
J. Phys. D: Appl. Phys. 47 (2014) 205103

15. Single layer fluorescent yellow OLED
Fluorinatedalcohol
Ethanol
19
TRL-4
Calvin Yi Bin Ng, Keat Hoe Yeoh, , Thomas J. Whitcher, Noor Azrina
Talik , Kai Lin Woon, Thanit Saisopa, Hideki Nakajima, Ratchadaporn
Supruangnet and Prayoon Songsiriritthigul,
Journal of Physics D: Applied Physics 47 205103 (2014)

16. Single layer fluorescent yellow OLED
19
TRL-4
The device with MoO3 shows efficiencies up to
(22.8 ± 2.5) cd/A with (14.3± 1.9) lm/W having
CIE coordinate of (0.48, 0.52).
N.A Talik, K.L Woon, .K Yap, W. S. Wong, T.J.Whitcher, N. Chanlek,H.
Nakajima, T. Saisopa, P. Songsiriritthigul,
Journal of Physics D: Applied Physics (2016) accepted

17. TANDEM OLED
N.A Talik; K.H Yeoh; C.Y.B Ng; B.K. Yap; Kai Lin Woon, Journal of Luminescence, 154,345, (2014)
TRL-3
Tandem OLED is two or more OLEDs
combined into a single unit.
Cd/A also increase. Have been
demonstrated in vacuum process
We are the first group in the world to
demonstrate it in solution process.
Very challenging to make tandem OLEDs
by solution process.

18. High Work function ITOTRL-4
Science 20 May 2011
Inspired by the science paper
ITO
Cl Cl Cl Cl Cl
We are trying to do
ITO
F F F F F
ITO
Spin coat
CsF..bake it and
Wash with water
T. J. Whitcher, K. H. Yeoh, C. L. Chua,
K. L. Woon, N. Chanlek, H. Nakajima,T.
Saisopa,and P.Songsiriritthigul J. Phys.
D: Appl. Phys. 46 (2013) 475102
What we discover, it is not the F, but
the flattening of the surface of ITO

19.  The use of grid computing
to pre-screen materials to
be synthesized. To
optimize the energy level
of molecules and triplet
energy.
 The need to benchmark
the theory and experiment
=> calibration curve.
27
Computational study
Bee Kian Ong, Kai Lin Woon, Azhar Ariffin Synthetic Metals,195,54 (2014)
TRL-2

20. 27
Computational studyTRL-2
One of important parameters for high triplet energy is short conjugation for blue OLED
High torsional angle between 2 rings
tend to give high triplet energy
38 molecules are studied
N
H
N
N
H
N
N
N
N
N
N
N
N
H
N
N
N
N
N
N
N
N N
DTFT is
performed to
calculate the
triplet energy.
The red
indicated
triplet energy >
2.95eV good
for the blue

21. Engineering High triplet
Materials
K. L. Woon, Z. A. Hasan, B.K.Ong, A. Ariffin, R. Griniene,S. Grigalevicius, Show-An Chen RSC Adv. ,2015, 5 , 59960–59969
TRL-3
In contrast with widespread belief, triplet energy in solid is more important.
Most measurement is done in liquid. The intermolecular distance can influence the triplet
energy.

22. 28
Engineering High triplet
Materials
TRL-3
Exciton confinement can be quantified by radiative lifetime.
100% triplet exciton
confinement possible
100% IQE OLED possible
ZAH-4
ZAH-2

23. Engineering High triplet
Materials (3rd generation material)
TRL-3
Fluorination induces stability (just like Teflon).
Let look at how fluorination helps in OLED materials
Red-shift the emission. Reduce
bandgap.
Maintain triplet energy except with the
ter-butyl group
Kai Lin Woon, Zakaria Nurul Nadiah, Zainal Abidin Hasan, Azhar Ariffin, Show-An Chen
Dyes and Pigments, 132, 1–6 (2016)

24. Material synthesisTRL-3
0.5g needs to be synthesized for device testing
a) Cu, K2CO3
, 18
-
Crown-
6, 1,2
-
dchlorobenzene, 180o
C
II
I I
I I
I
I
a
a a
a
N
H
N
N
9 (70%)
10 (70%)
12 (70%)
11 (70%)
N
NN
N
N N
N
NN
N
N N
N
NN
N
N N
N
NN
N
N
N
ET =2.71eV ET=2.82eV ET = 2.53eV ET = 2.73eV
Tg =224oC Tg = 270oC Tg =198oC Tg =274oC

25. Material synthesisTRL-3
Journal of Luminescence 2016 (accepted)

26. TRL-4 EXTRA WARM WHITE OLED
Strong-blue emission drastically suppresses the secretion of melatonin (MLT). Increase the risk of breast,
colorectal, and prostate cancers.*
* Pauley S. M., “Lighting for the human circadian clock: recent research indicates that lighting has become a public health issue,” Med. Hypotheses.
63, (4 ), 588 –596 (2004)
Device structure
+ energy level
0.2 0.3 0.4 0.5 0.6 0.7
0.2
0.3
0.4
0.5
0.6
0.7
1000cd/m2
6551cd/m2
y
x
Plankian locus
Device
1cd/m2
0.1 1 10 100 1000 10000
0
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
Brightness (cd/m2
)
CurrentEfficiency(cd/A)
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
PowerEfficiency(lm/W)
400 450 500 550 600 650 700
0.0
0.2
0.4
0.6
0.8
1.0
Intensity(Count(Normalize))
Wavelength (nm)
Performance of
Device
Value
Startup voltage (V) 4.0
Colour
temperature @
1000cdm-2
2500K
Maximum current
efficiency (cd/A)
26.0
Maximum power
efficiency (lm/W)
13.6
CIE Coordinate
when 1000cd/m2
(0.4832,
0.4273)

27. Conclusions
1. We have developed various techniques for improving the device
efficiency with commercial available materials.
2. We have developed a methodology to screen large amount of
molecules.
3. We have synthesized light emitting host and defined new
material requirement for high efficiency organic LED.
4. We have built a theoretical framework for the organic-organic
and inorganic-organic interfaces for low driving voltage devices.

28. Patent Filed under OLED project
1. Organic light emitting diode and method of preparation thereof), Patent, PI
2013700871, 2013, (National)
2. ENHANCED ELECTRON INJECTION ORGANIC LIGHT EMITTING DIODE, Patent, PI
2013003279, 2014, (National)
3. A Method of tuning an indium tin oxide (ITO) work function, Patent, PI 2014700191,
2014, (National)
4. Organic LED has non-cross linked emissive layer consisting of electron and hole
transporting hosts doped with electron blue phosphorescent emitters where non-
emissive hole transporting layer is cross-lined materials, Patent, WO2014193215-A1,
2014, (International)
5. PHOLED AND METHOD OF FABRICATING THEREOF, Patent, PI 2015704576 , 2016,
(National)
6. PHOSPHORESCENT ORGANIC LIGHT EMITTING DIODE (PHOLED) MATERIAL, Patent, PI
2015703855, 2015, (National)

29. People who are involved in this Project
University Malaya, Physics Department
1. Woon Kai Lin
2. Yeo Keat Hoe
3. Thomas J Whitcher
4. Noor Azrina Talik
5. Calvin Ng
6. Wang Seng Wong
University Malaya, Chemistry
Department
1. Azhar Arrifin
2. Zainal A. Hassan
3. Nurul Nadia
4. Bee Kian Ong
National Tsing Hua University, Chemical
Engineering Department
1. Show-An Chen
Thailand Synchrotron Light Source,
Thailand
1. Narong Chanlek
2. Hideki Nakajima
3. Thainit Saisopa
4. Prayoon Songsiriritthigul
Department of Polymer Chemistry and
Technology, Kaunas University of
Technology, Lithuania
1. Raimonda Griniene
2. Saulius Grigalevicius
University Tenaga Nasional, College of
Engineering
1. Dr Yap Boon Kar
University of Hull
1. Mary O’ Neill

30. 32
ACKNOWLEDGEMENT
Funders
1. UM Postgraduate Research Grant (PPP) PG071-2013A, PG112-2012B
2. MOHE Fundamental Research Grant (FRGS) FP005-2013A
3. MOSTI E-science (16-02-03-6030)
4 University Malaya Chancellery Research Grant (C-HIR)
(UM.C/625/1/HIR/195) and (UM.C/625/1/HIR/208)
5 UK Royal Society Travel Grant
6 Itramas Technology Sdn Bhd
~ RM 1.5 million is spent on this project over 5 years
(equipment, consumables, human capital)