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Homer Antoniadis | OLED Product Development|page:1
An Overview of OLED Display Technology
Homer AntoniadisOSRAM Opto Semiconductors Inc.
San Jose, CA
Homer Antoniadis | OLED Product Development|page:2
Outline
! OLED device structure and operation
! OLED materials (polymers and small molecules)
! Evolution of OLED performance
! OLED process and fabrication technologies
! White emitting OLEDs
! Color capabilities
! Products and demonstrators
Homer Antoniadis | OLED Product Development|page:3
Single pixel structure
Anode (ITO 1500 Å)
Conducting polymer layer ~ 1200 Å
Emissive polymer layer ~ 800 Å
Cathode (Ba,Ca/Al 2000 Å)
Conducting polymer layer
Glass substrate
Epoxy
Anode
Cathode
Cover glass
Emissive polymer layer
OLED display and pixel structure
Display Pixel
Human hair is 200X the thickness of the OLED layers
Homer Antoniadis | OLED Product Development|page:4
Lighth+ h+
h+
e- e-
Transparentsubstrate
Anode(ITO)
Conductingpolymer Emissive polymer
HOMO
LUMO
Cathode-layer (s)
ca. 100 nm 10 - >100 nm <100 nm
LUMO
HOMO
>100 nm
OLED device operation (energy diagram)
light
Anode+ ++ + ++ + ++
_
++ +
Cathode_ _ _ _ _ ___+_ _+
VEmissive polymer
Conducting polymer
OLED Device Operation Principles
OLEDs rely on organic materials (polymers or small molecules) that give off light when tweaked with an electrical current! Electrons injected from cathode! Holes injected from anode! Transport and radiative recombination of electron hole
pairs at the emissive polymer
Homer Antoniadis | OLED Product Development|page:5
-8 -6 -4 -2 0 2 4 6 8
10-7
10-6
10-5
10-4
10-3
10-2
10-1
100
Voltage (Volts)
Cur
rent
Den
sity
(A/c
m2 )
Luminance-Current-Voltage Efficiency-Luminance-Voltage
0 2 4 6 810-1
100
101
102
103
104
105
Voltage (Volts)
Lum
inan
ce (c
d/m
2 )
0 2 4 6 80
2
4
6
8
10
12
Voltage (V)
Effic
ienc
y (c
d/A)
10 100 1000 100002
4
6
8
10
12
Luminance (cd/m2)
Effic
ienc
y (c
d/A)
Optoelectronic Device Characteristics
LUMINANCE is the luminous intensity per unit area projected in a given direction
The SI unit is the candela per square meter (cd/m2), which is still sometimes called a nit
The footlambert (fL) is also in common use: 1 fL = 3.426 cd/m2
http://www.resuba.com/wa3dsp/light/lumin.html
Homer Antoniadis | OLED Product Development|page:6
Evolution of LED performance
SM OLED
PolymerOLED
Courtesy of Agilent Technologies
Homer Antoniadis | OLED Product Development|page:7
Conducting polymers! Polyaniline (PANI:PSS)! Polyethylenedioxythiophene
(PDOT:PSS)
Emissive polymers! Polyphenylenevinylene (R-PPV)
! Polyfluorene (PF)
Processed by :Spin casting, Printing, Roll-to-roll web coating
IP owned by Cambridge Display Technology
R1R1
n
R1
R1n
NH
PANI PDOT
R-PPVPF
Electroluminescent Conjugated Polymers
PSS
Homer Antoniadis | OLED Product Development|page:8
Multiple emission colors achieved by Covion
300 nm 500 nm 700 nm
n
CNOR
ROS
PPP
PPV
PT orCN-PPV
Different emission colors can be obtained with a variety of chemical structures
Homer Antoniadis | OLED Product Development|page:9
Multiple emission colors achieved by Dow Chemical
R1R1
n
PF
Homer Antoniadis | OLED Product Development|page:10
Deposit and pattern anode (ITO)
Vacuum deposit and pattern cathode (Ba,Ca/Al)
Pattern polymer layers(first conducting then emissive)
Spin coatingInk Jet printing
Web coatingScreen printing
Polymer OLED display fabrication steps
Homer Antoniadis | OLED Product Development|page:11
Ink Jet printing to define and pattern R, G, B emitting subpixels
Ink Jet Printing to Pattern Polymers(Full Color Applications)
Substrate
Greenemitter
Red emitter
Blue emitter
Ink Jet Head
Homer Antoniadis | OLED Product Development|page:12
The Holy Grail: Flexible OLEDs
Sheila Kennedy, Harvard Univ., 1999
Homer Antoniadis | OLED Product Development|page:13
Small molecule
Anode - ITOHIL - CuPc
Substrate - glass
EML - doped Alq3
ETL - Alq3
HTL - NPB
Cathode - Li/Al
Anode - ITO
Substrate - glass
ETL - PPV, PF
HIL - PDOT, Pani
Cathode – Ba, Ca/Al
Multi-layer structuremade all in vacuum
Bilayer structuremade from solution
Polymer
Polymer and Small Molecule Device Structures
Homer Antoniadis | OLED Product Development|page:14
Hole transport small molecules! Metal-phthalocyanines! Arylamines, starburst amines
Emissive small molecules! Metal chelates, distyrylbenzenes! Fluorescent dyes
Processed and deposited by :thermal evaporation in vacuum
IP owned by Eastman Kodak
NO
NO
Al O
N
N N
Alq3
NPD
Electroluminescent Small Molecules
Homer Antoniadis | OLED Product Development|page:15
Alq3
substrate
NPD
Shadow mask
ITO
ITO
Shadow mask
ITO
Cathode separator
Small molecules are thermally evaporated in vacuum R, G, B pattering is defined by
shadow masking in vacuum
Full color patterning with small molecules
R emission layer
G emission layer
B emission layer
Shadow mask
Homer Antoniadis | OLED Product Development|page:16
White emitting small molecule OLEDs
Initial Luminance 1000nits
Homer Antoniadis | OLED Product Development|page:17
Phosphorescent small molecule OLED (both singlets and triplets are harvested)
ηext=19% and ηint =87%
Homer Antoniadis | OLED Product Development|page:18
Advantages:- well-established technology (LCD)- no patterning of emitter necessary- homogeneous aging of emitter (?)
Color filtersWhite emitter
Disadvantages:- power inefficient - ITO sputtering on filters- efficient white emitter necessary
RGB- polymer emitters
Advantages:- power efficient- lower production cost- mature ITO technology
Disadvantages:- emitters have to be optimized separately (common cathode?)
- differential aging of emitters- patterning of emitters necessary
Color Changing Media(CCMs)
Advantages:homogeneous aging of emitter (?)more efficient than filtersno patterning of emitter necessary
Disadvantages:ITO Sputtering on CCMsstable blue emitter necessary aging of CCMs
Full-color/Multi-color Approaches
Homer Antoniadis | OLED Product Development|page:19
Ink Jet printing of R,G,B emissive polymers defines the R,G,B subpixels
(xR, yR) (xG, yG) (xB, yB)
AM TFT screen
Green polymer
Red polymer
Blue polymer
EL I
nten
sity
(nor
mal
ized
)
400 450 500 550 600 650 700 7500.0
0.2
0.4
0.6
0.8
1.0
Wavelength (nm)
Obtaining a Full Color OLED Display
G BR
Homer Antoniadis | OLED Product Development|page:20
Device Color, Efficiency and Lifetime
>30,0008>30,0008-10Yellow
20,0006-85,0002-4White
10,00033,0004Blue
>40,000
>40,000
Half-Life* (hrs)@150 nits, RT
8-915,0008-10Green
4-5>20,0001-2Red
Efficiency (cd/A)
Half-Life* (hrs)@150 nits, RT
Efficiency (cd/A)Color
Small MoleculesPolymers
*Extrapolated Lifetime under constant current conditions
Homer Antoniadis | OLED Product Development|page:21
Small Molecule Passive Matrix Display Products
Lucky Goldstar (LG)
Motorola (by Appeal)
Samsung ElectronicsKodak Licensed SNMD toManufacture PM OLED Displays
96x64 Full Color PM Display
Homer Antoniadis | OLED Product Development|page:22
Small Molecule Active Matrix Display Products
Eastman Kodak: Digital camera Sanyo: Cell Phone with Digital camera
Homer Antoniadis | OLED Product Development|page:23
Top Emission Adaptive Current Drive technology, allows OLEDs to be larger and higher in brightness and resolution. A 13-inch full-color AMOLED using poly-Si TFT was made where the light emits through the transparent cathode and thus, the filling factor does not depend on the TFT structure.
The schematic vertical structure of the device is substrate/TFT/metal anode/organic layers/transparent cathode/passivation layer/transparent sealing.
Display format: 800 x 600 (SVGA); pixel pitch 0.33x0.33mm2
Top Emitting Active Matrix OLED Display
Homer Antoniadis | OLED Product Development|page:24
Polymer Passive Matrix Display Products
Delta Electronics: Display for MP3 playerPhilips: Electrical Shaver
Homer Antoniadis | OLED Product Development|page:25
OSRAM Opto Semiconductors evaluation kit
San Jose, CA – May 15, 2003 -- Osram Opto Semiconductors, a global leader of solid-state lighting devices, today announced its Pictiva� Evaluation Kit. Announced earlier this week, the Pictiva brand is Osram�s suite of organic light emitting diode (OLED) technologies. Pictiva displays offer a high level of brightness and contrast, video capabilities, wide viewing angles and a thin-profile, enabling developers and engineers to have greater design flexibility when developing the next-generation state-of-the-art electronics products.