Roll-to-Roll OLED for LightingMi (M ti ) Y L T D id J S ith Ah t Gü E l tMin (Martin) Yan, Larry Turner, David J. Smith, Ahmet Gün Erlat, Brian Scherer, Ri-an Zhao, Anil Duggal
GE Global Research
AIMCAL Fall Technical ConferenceOctober 21 2009October 21, 2009
What is an OLED?
• Light emission occurs when charges injected from opposite electrodes recombine in organic layer(s).
Tremendo s technolog gro th o er last• Tremendous technology growth over last decade driven by display industry.
• Not an inorganic LED! Amorphous films!
Current technology not roll-to-roll!
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Current technology not roll to roll!
OLED Offer Novel Features for New ProductsMechanical Flexible Thin and Light TransparentMechanical Flexible Thin and Light Transparent
Color TunableColor Tunable
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OLED Development Paradigms
“Evaporated” “Solution-Processed”
Organic layers evaporated Organic layers coated orOrganic layers evaporatedin high vacuum
CathodeCathode
Organic layers coated or printed from solution
Cathode
Transparent AnodeTransparent Anode Transparent Anode
• More mature technology.T i ll l (4 20)
• Typically fewer layers (2-3).
Transparent AnodeTransparent Anode p
• Typically more layers (4-20).• Difficult to scale to large area.
• Development cycle is slower.• Potential for much lower cost.
(“S ll l l ” h) (“Polymer” or “Large Molecule”
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(“Small-molecule” approach) ( Polymer or Large Molecule approach)
GE OLED Vision
“Lighting Wallpaper”
• Energy Efficient• Low Cost• Low Cost• Thin and Flexible
New design possibilities could change the way we think abo t lighting!
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think about lighting!
R i t A i t C l Hi h CRI C l St bilit L C t
Approaches to Illumination-Quality Light
Independent RGB Elements
Requirements: Appropriate Color High CRI Color Stability Low Cost
Single White Emission LayerSubstrate/ITO
+ Color tunability possible.
Cathode+seal
Organic layers
+ Simple, low cost designs possible.
Down-conversion from Blue
+ Active means for color stability- Extra complexity/cost.
- Materials challenge (single chromophore).- Color stability (multiple chromophores)
Multiple (RGB) Emission Layers
Substrate/ITO
White Light
V
Downconversion Layer
Organic layers
Down conversion from Blue Multiple (RGB) Emission LayersSubstrate/ITO
Organic layers
VCathode+seal
Organic layers
+ Simple, low cost design.+ Inherently color stable.
Cathode+seal
+ Single material set can cover all applications.- Complex device design.
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- Relies completely on blue OLED - Color stability with life and brightness.
Large Area Devices are Possible
series current pathseries current path
1 element
5 element
12 element
• Distributes current over a large area in spite of resistive electrode.• Device architecture is tolerant to shorting faults.
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October 21 2009APL 82, 2580 (2003)
Roll-to-Roll OLED Fabrication
OLED R2R Line Old Techniques + New Inventions
NIST ATP P (2003 2007)NIST ATP Program (2003-2007)Partner – Energy Conversion DevicesGoal – Prove that continuous roll-to-roll OLED fabrication is possible.Goal Prove that continuous roll to roll OLED fabrication is possible.
OutputModular roll-to-roll line for designed for manufacturing research
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Modular roll-to-roll line for designed for manufacturing research.
First Output of Roll-to-Roll Line
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Common early output.
Current output. Low cost, high performance OLED
lighting product
E i i /Advanced device
Engineering / debugging
structure / high performance material / upgraded hardware/ optimized process
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Roll-to-Roll Manufacturing Choices
W t ti t h i ( )? H ti th d?Wet-coating technique(s)? Hermetic method?Print organics directly? Glass luminaire?
Ultra high barrier coating?Inkjet, gravure, flexographic?
Blanket coating + post-patterning?Ultra-high barrier coating?
As substrate?As encapsulation?As luminaire?
j , g , g p
Laser ablation?M h i l ib ?
Hybrid wet/dry process? All-wet process?
As luminaire?
System integration method? Printable cathode?
Mechanical scribe?
System integration method?
Dry deposition rate/cost?
Atmosphere-vacuum transition?Intermediate roll-up?
Printable cathode?
Lamination?
Dry deposition rate/cost?
• Correct answer changes as device designs/materials evolve.• Research roll to roll line allows ongoing evaluation of alternatives
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• Research roll-to-roll line allows ongoing evaluation of alternatives.
Unique to OLED Example 1 - SAW“Solvent-Assisted-Wipe” - Mechanical scribe-like technique for organicsSolvent Assisted Wipe Mechanical scribe like technique for organics.
ConceptConcept
Appropriate solvent choice enables …Simultaneous removal of all organic layers without damaging underlying i i ti l ti binorganic coatings on plastic web.
ORSelective removal of specific organic layer.
Roll-to-roll implementation works!
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The Problem
Unique to OLED Example 2 - UHB
OLEDTransparent electrode
Polymeric substrateH2O O2
Commercial available polymeric substrate
The Solution3,530 hrs at 23°C 40%RH
OLED
Graded ultra high barrier
Transparent electrode
Chem resist layer
High heat polycarbonate
Chem resist layer
GE Ultra-high Barrier (UHB) Substrate
H2O O212 mm
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Proved that high barrier substrate is possible
Defect-Driven Moisture Permeation
1000 Uncoated
Non-Fickian Diffusion ~ 100 defects/mm2
Defect Imaging w/ Acetone
10
100
100%
O2
20x
~1mm
Defect Imaging w/ Acetone
0.1
1
@ 2
50 @ ~1mm
1 10 100 1000
0.01
0.1
OTR
Detection limit
SiNx Thickness (nm)
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Barrier performance of single layer inorganic coating is defect limited
Permeation Simulation: Multilayered Barrier
Assumptions: - 2 perfect barriers
Fick’s Law:
C ti it
1
ConductionLi it d
p- each barrier has 1 defect- defects are offset/decoupled
Continuity:
DiffusionEquation:
LimitedRegime
Rat
io
Low
0 1
Flux
R
Flux Ratio =Flux2 Layer System
Flux 1Barrier System
High 0.1 1 10
0.1
Distance/Offset
Offset
DistanceWork in this regime toachieve Ultra-High Barrier
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GE’s Approach: Graded Ultra-high Barrier (UHB) by Plasma Enhanced Chemical Vapor Deposition (PECVD)
XPS Spectrum of Graded UHBGE’s Graded Ultra High Barrier
InorganicOrganiczone Inorganic zone
Cross-sectional TEM of Graded UHB (made in batch mode)
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Continuous composition transition
Ultra-high Barrier Performance Test: Ca-test2. Defect Imaging1. Continuous - WVTR
EpoxyCa
B i C ti
Glass
2. Defect Imaging
PolycarbonateBarrier Coating
60C/90%RH
W t
23°C/50RH
CaWater vapor permeation over time
8 mm
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Roll-to-roll (R2R) UHB Process Development
• Achieved graded structure. • Achieved ultra-high barrier performance (low
10-5 g/m2/day)10 g/m /day). • Good transparency. • Good coating adhesion (5B in ASTM3359 tape
pull test).
80
100
40
60%
T
R2R UHB coatedBare substrate
0
20
350 400 450 500 550 600 650 700 750 800
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Wavelength (nm)
Energy Dispersive X-ray Spectroscopy (EDS)SiOxNySiOxNy
Graded Structure of R2R UHB
T i i El Mi (TEM)
SiOxNySiOxCy
SiSiOxNySiOxCy
Si
glue
Si substrate
Transmission Electron Microscopy (TEM)
12345
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Achieved graded coating structure.
Ultra-high Barrier Performance of R2R UHB
Continuous WVTR Ca test
8 inch web
Continuous WVTR Ca test
Defect imaging Ca test.1
2
3
1
2
3
Defect imaging Ca test @ 60°C 90%RH Continuous WVTR Ca test @ 23°C 50%RH
Polycarbonate
EpoxyCa
Barrier Coating
Glass
Polycarbonate
EpoxyCa
Barrier Coating
Glass
• Cell 1: 2.2 × 10-5 g/m2/day. 1
• Cell 2: 1.5 × 10-5 g/m2/day. • Cell 3: 1.7 × 10-5 g/m2/day. • Glass/glass control 1: 7.2 × 10-6 g/m2/day • Glass/glass control 2: 8.4 × 10-6 g/m2/day
2
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g g y
3
Unique to OLED Example 3 - Lamination
Lamination without vacuum achieves same efficiency asachieves same efficiency as conventionally processed device.
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…Need better adhesion for large area devices.
APL 88, 223509 (2006)
ConclusionsR ll t ll i /fl ibl l t i i l• Roll-to-roll organic/flexible electronics is real.
• OLED Lighting is getting closer!
Acknowledgements
GE OLED TeamEnergy Conversion Devices
Acknowledgements
Department of EnergyFlexTech Alliance
Energy Conversion Devices
FlexTech AllianceNIST ATP Program
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