LARGE-AREA INTEGRATED SUBSTRATE FOR OLED LIGHTING
O L E D T r a c k S e s s i o n D o E S O L I D S T A T E L I G H T I N G M A N U F A C T U R I N G R & D W O R K S H O P , S a n D i e g o , C A
C h e n g - H u n g H u n g , D e n n i s O ’ S h a u g h n e s s y , A s h t o s h G a n j o o , J a m e s M c C a m y , A b h i n a v B h a n d a r i
P P G I n d u s t r i e s
May 7, 2014
OUTLINES
Introduction
Integrated substrate
Internal Extraction Layer (IEL)
Anode
Summary
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THE BIG PICTURE DoE Program Goal: Substantial energy savings
Reference
OLED LED
Quad
s of
Ene
rgy
Source: DoE Report- Energy Savings Potential of SSL in General Illumination, 2010
Scenario 2015 2020 2025 2030 Cumulative
OLED 0.01 0.36 0.96 1.51 10.49
$ Saving* (Billion)
0.085 3.06 8.16 12.84 89
Potential U.S. Energy Savings in Quads
*Assumption: 1 Quad Production~ $8.5 Billion
1 quad/yr energy saving needs ~3 x 109 ft2 OLED panels#.
3 # Assuming 0.17 ft2/w, 120 lm/W, and 50% efficiency improvement
A typical float glass line produces ~3 x 108 ft2 glass per year.
Cover up 52,000 football fields
Need 10 float lines
0510152025303540
0%
5%
10%
15%
20%
25%
30%
35%
Cost
($/m
2 )
Cost
(%)
DOE Targeted OLED Material Cost
MATERIAL COST AND SUBSTRATE SIZE
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0
10
20
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Area
(m2 )
Shor
t Sid
e D
imen
sion
(in)
Substrate Generation
OLED Substrate Size Trend
2007
2011
Source: DOE SSL Manufacturing Roadmap, 2013
~40% for integrated substrate
Need for low cost, large area integrated substrates. Float glass manufacturing process can meet this need. 4
Float line glass dimension
Previous DOE Project Accomplishments
• Demonstrated 73% efficiency increase possible using a combination approach (IEL+EEL)
• Current project, Manufacturing process for OLED integrated substrate, is supported by US Department of Energy (DE-EE-0006261).
DOE R&D Award DE-EE0003209
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CURRENT DOE PROGRAM
Objectives: Manufacturing process development of a low-cost “integrated” float glass based substrate product for large area OLED panel lighting. Cost Target: $60/m2 by 2015 and $28/m2 by 2020
Performance Target: 50% extraction efficiency
enhancement; 10-15 ohms/sq sheet resistance (lower with grids)
2 Years manufacturing process development program in partnership with UDC and Plextronics started in August 2013.
Device Manufacturing & Testing
Hole Injection Layer (HIL) Application & Screening
Integrated Substrate Manufacturing
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IEL/EEL and Anode Metrics METRICS
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IEL/EEL Metrics Project Goals
Light Outcoupling Efficiency 50% enhancement for IEL & EEL Combination
Surface Quality Compatible with device manufacturing
Chemical and Mechanical Durability
Stable against buffer and light emitting materials Compatible with OLED processing
Anode Metrics Project Goals
Low Resistance & High Transmission
10-15 Ω/� and 85% transmission across visible spectrum
Work Function > 5eV
Surface Roughness < 10 nm RMS (without planarizing layer) RPeak to Valley < 50 nm (without planarizing layer)
Chemical Migration Electrochemically stable in contact with cathode material No migration of conductive particles
Chemical and Mechanical Durability
Stable against buffer and light emitting materials Compatible with OLED processing
Deposition Defects <<1 Pinhole of 0.5 µm/mm2
PPG Integrated Manufacturing Process
Both IEL and anode layer (TCO) applied in a low-cost float glass manufacturing process.
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IEL Tool CVD Coater
Sketch of float glass manufacturing process
PROGRESS ON INCORPORATION OF LIGHT SCATTERING ELEMENTS
Glass samples made in an on-line process A lab sample with targeted haze
• Glass samples illuminated with an edge light
Significant progress on on-line IEL development toward target requirements.
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CVD ANODE TECHNOLOGY
On-line produced transparent conductive oxide (TCO) is crystalline. Large crystals give better sheet resistance and poorer surface roughness.
(a crystalline material)
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PROGRESS ON SMOOTHENING ANODE SURFACE
Without smoothening oxide layer
• Scanning Electron Microscope (SEM) planar view images
Smoothening oxide layer used in on-line anode manufacturing process.
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With smoothening oxide layer - Improved 20% on Rq and ~30% on Rp-v
HOLE INJECTION LAYER (HIL) Purposes
• Planarization of rough substrates, thereby preventing shorts between anode and cathode, increasing yield, and reducing cost
• HIL materials can improve hole injection and extend device lifetimes
Sketch of HIL on anode Devices fabricated on anode without HIL (left) and with HIL (right)
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SUMMARY
The state of the art in the lab has progressed significantly.
IEL trials with the pilot are in progress, with significant improvement of embedding and better understanding the challenges.
Smoothening oxide layer is used in on-line anode process. OLED lighting performance is being evaluated.
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