development of oled lighting applications using...
TRANSCRIPT
Development of OLED Lighting Applications Using Phosphorescent Emission System
Kazuhiro Oikawa
R&D Department OLED Lighting Business Center
KONICA MINOLTA ADVANCED LAYERS, INC.
October 10, 2012
1
Outline
KONICA MINOLTA’s OLED lighting development
• Evaporation and Solution Process • OLED Efficiency Improvement • Production Case Study of OLED Lighting
World’s first all-phosphorescent OLED product
• Proprietary blue phosphorescent emitter
Roll-to-Roll process OLED technology
• Unique material technology and OLED structure for solution process • Recent progress in solution-processed OLED device • R2R OLEDs line
Summary
2
OLED development at KONICA MINOLTA
World-record performance presented in SID2007
Demonstration of OLED lighting by R2R process
Evaporation Solution Process
3
Goals for OLED Development
All phosphorescent
High productivity
Low greenhouse gas emission lightings
High efficiency
Low cost to compete with conventional lightings
Solution Process
4
OLED Efficiency Improvement
Light extraction capability
n1
n2
n3
nair
For lighting application, [€/lumen] tells
the competitiveness of a luminaire.
It is quite important to improve the luminous efficacy for lighting applications.
Carrier balance
Electron Hole
OLED (external) quantum efficiency is given by the formula;
Ratio of emissive exciton •Fluorescence: 25% •Phosphorescence: 100%
Ratio of emission per number of exciton
Phosphorescence has significant advantage over fluorescence
Heat
Light
5
Production Case Study of OLED Lighting
R2R solution process has the potential to significantly reduce costs due to scalability through both the substrate width and the coating speed.
Pro
duct
ivity (
m2/m
in.)
0.1
100
10
1
1 2 3
Substrate Width (m)
0
G10,TACTs:45s
G10,TACTs:180s
G4,TACTs:90s
G6,TACTs:60s
G8,TACTs:60s
G8,TAKT:180s
G6,TACTs:180s
G4,TACTs:180s
G2.5,TACTs:180s
Expected productivity by Evaporation
R2R Process Target (Past results: photographic material coating)
Desired productivity for general lighting application 10 million m2/year
6
Outline
KONICA MINOLTA’s OLED lighting development
• Evaporation and Solution Process • OLED Efficiency Improvement • Production Case Study of OLED Lighting
World’s first all-phosphorescent OLED product
• Proprietary blue phosphorescent emitter
Roll-to-Roll process OLED technology
• Unique material technology and OLED structure for solution process • Recent progress in solution-processed OLED device • R2R OLEDs line
Summary
7
World’s First All-phosphorescent OLED Product
All-phosphorescent OLED lighting product using our proprietary blue emitter
Items Performance
Luminous efficacy 45 lm/W
Thickness 1.9 mm
Area 55 cm2
Luminance 1000 cd/m2
Current / Voltage 71.5 mA / 3.6 V
Color coordinate (x,y)=(0.45,0.41)
Life time (LT50) 8,000 hrs
Color temperature 2800 K
8
0.0001
0.001
0.01
0.1
1
10
450 500 550
Emission Wavelength (nm)
Rela
tive L
ifetim
e
Proprietary Blue Phosphorescent Emitter
Conventional Phenylpyridine-Ir metal complex has no solution !
Phenylpyridine-Ir metal Complex
Flrpic
Ir(ppy)3
New type proprietary blue emitter
9
Wide Band-gap Materials Design
Necessity of Host with high triplet energy for Phosphorescent emission
Molecule Design Policy
1. High T1 energy 2. High Tg 3. High carrier transport ability 4. Amorphous morphology
Jablonski Level Diagrams
Fluorescent emission
Host
S1(H)
S0(H)
Band Gap
S0(D)
Emitter
hν
S1(D)
Host
Phosphorescent emission
S0(H)
Wide Band Gap
T1(H)
Emitter
T1(D)
S0(D)
hν
S1(H)
10
Outline
KONICA MINOLTA’s OLED lighting development
• Evaporation and Solution Process • OLED Efficiency Improvement • Production Case Study of OLED Lighting
World’s first all-phosphorescent OLED product
• Proprietary blue phosphorescent emitter
Roll-to-Roll process OLED technology
• Unique material technology and OLED structure for solution process • Recent progress in solution-processed OLED device • R2R OLEDs line
Summary
11
Overview of R2R Solution Process Work
Flexible Substrate
Anode Organic Thin Layers
Cathode Adhesive
High performance & low cost
•process environment
•Cleaning
•Coating & drying
•Web handling
•Lamination
•Quality inspection
•Transparent conductive film
•Patterning
•Encapsulation
•Packaging
•Interconnection
•Multilayer design
•Thickness
•Charge balance
•Film morphology
•Light out-coupling
•High-Barrier film
•Plastic substrate
•Metal substrate
•Ultra-thin glass
•Phosphorescent emitter and host materials
•HILs and HTLs
•ETLs
•Solvents
Materials Layer design Substrate Device design R2R Process
12
Design for Four-layer Solution Process
HIL
HTL
EML(Host+Emitter)
ETL
Solution- processed four layers
EIL
Phosphorescent small molecules system
Cathode
Anode
Key Items
• All phosphorescent system using proprietary solution processable blue emitter • Unique material system to avoid lower layer wash-off • Optimization of each layer’s solution formulation • Process condition to be compatible with plastic substrate
2010 White OLED with light out-coupling
Luminance cd/m2 1,000
Efficacy lm/W 52
Driving Voltage V 3.5
Life time (LT50) hrs 6,000
Color coordinate (x,y)=(0.46,0.42)
CCT K 2,800
13
Analysis of Organic Multilayer Thin-film
HIL HTL
EML
ETL
Anode
Cathode Cathode
Anode
Cross-sectional observation by STEM
Evaporation Solution Process
100 nm 100 nm
HIL
HTL
EML
ETL
Clear interfaces in multilayer structure as well as evaporation
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All-Evaporation HIL only (Solution)
HIL/HTL (Solution)
All-Solution Process
HIL/HTL/EML (Solution)
HIL/HTL/ETL (Solution)
= EML only (Evaporation)
Performance Comparison on an Identical Design
Major factor limiting the performance : Solution-processed EML
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What is the difference in EML ?
EML’s morphological properties can be a cause.
• Crystallization
• Molecular aggregation
• Film density
• Impurities
ETL
HTL
ETL
HTL
Host Emitter Impurities
Evaporation Solution Process
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0
2000
4000
6000
8000
10000
12000
14000
16000
18000
20000
2 7 122θ
I(co
unts）
Evaporation
Solution Process
EML(Host+Emitter)
Glass
Film morphological improvement 1
X-ray
XRD analysis using Synchrotron radiation (SPring-8)
High brightness High directionality
Variable polarization
Small Angle X-ray Scattering(SAXS)
Particle size
Wide Angle X-ray Diffraction(WAXD)
Molecular Orientation
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5
6
7
8
9
10
11
0.000 0.002 0.004 0.006 0.008q2
Ln[I
(q)]
Evaporation
Solution process
Film morphological improvement 2
q: Scattering vector Rg: Radius of gyration
λ: Incident X-rays wavelength(nm) q: Scattering angle I(q): Scattering Intensity
SAXS analysis by Guinier plot
0
0.2
0.4
0.6
0.8
1
1.2
0 5 10Particle diameter (nm)
Num
ber-
size
dis
trib
ution
Evaporation
Solution Process
Particle size analysis
22
22
)q3
Rg(-I(0) LnI(q) Ln
)3RgqI(0)exp(-I(q)
)sinλ
4(q
q
Guinier’s Law
Scattering body
2q
Incident
radiation
S 0 S
S 0
q:Scatterign vectorqq
Scattered
radiation
2Rg Slope
)3
Rg-(Slope2
Guinier plot
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ETL
HTL
Solution Process
Film morphological improvement 3
E E
E
T-T annihilation Quenching
Charge Energy Residual solvent Assisting E-E aggregation
transfer loss
No harmful effect Host Emitter
Impurities
Performance degradation by molecular aggregation
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0
0.2
0.4
0.6
0.8
1
1.2
0 5 10Particle diameter (nm)
Num
ber-
size
dis
trib
ution
Evaporation
Solution Process
Film morphological improvement 4
Full width at half maximum (2θ degree)
Solution process Improved
solution process Evaporation
1.0 1.7 1.8
SAXS
WAXD
• Adoption of new host material for solution process • Optimization of drying condition
0
0.2
0.4
0.6
0.8
1
1.2
0 5 10Particle diameter (nm)
Num
ber-
size
dis
trib
ution
Evaporation
Improved Solution Process
Improved effect
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Current Performance
All-Evaporation All-Solution Process in 2010
All-Solution Process in 2012
Our activities showed encouraging progress.
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R2R OLEDs Line for R&D
Patterning,
Cleaning
Wet coating & drying of
organic layers
Vacuum deposition
for electrode layers
Encapsulation,
Packaging
Quality inspection
22
Improvement of Defective Appearance
Key Focus
• Die Coating technology to form uniform coating a nanoscale organic layer
Optimization of various parameters ; • Slot die coater design with high accuracy
• Coating conditions for each layer • Drying instruments and conditions • Web handling ・・・・
Coating Failure Rate
23
Outcome from R2R OLEDs Line
Feasibility demonstration of all-phosphorescent OLED lighting panel by solution-based R2R process technology
Area : 94.5cm2 (63mm X 150mm) Thickness : 500µm Weight : 14g / panel
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Summary
All-phosphorescent OLED is a major breakthrough in OLED lighting. We have commercialized OLED lighting product by evaporation with the world’s highest-level efficacy using all phosphorescent emitters for the first time in the world. Successful demonstration of the all R2R-processed OLED panel has opened a way to achieve commercially viable OLEDs for general lighting applications. To catch up with the state-of-the-art evaporated OLED lighting, we will accelerate the development of the solution-processed OLEDs by combining advanced materials and innovative process technologies.
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Acknowledgements
NEDO project (P09024)
Philips Technologie GmbH for consignment production on the evaporated OLEDs
Universal Display Corporation for Universal PHOLED® Phosphorescent OLED technology
GE Global Research for collaboration on the solution process technology (March 2007~March 2011)
Japan Synchrotron Radiation Research Institute (JASRI)
