Contenu connexe Similaire à Arjan Langen - TNO/Holst Centre Similaire à Arjan Langen - TNO/Holst Centre (20) Arjan Langen - TNO/Holst Centre1. Large area coating for
flexible electronics
Arjan Langen TNO/Holst Centre
Themadag Mikrocentrum :
Organic and printed electronics
23 November 2012
2. Large area coating for
flexible electronics
• OLED
• OPV
• R2R manufacturing
• Web handling
• Slot die coating
• Contamination control
• Summary
• Holst Centre Large area printing
Presentation
overview
OLED - Organic light emitting diode
Organic and printed electronics 23 Nov 2012
3. © Holst Centre 5
OLED Lighting: relevant to society and economy
19% of all generated electricity goes to lighting
If OLED has 10% share in replacement market for lighting:
100.000.000 m2 OLEDs/year needed
Organic and printed electronics 23 Nov 2012
© Holst Centre 6
2009: First OLED lamps for sale on glass
Organic and printed electronics 23 Nov 2012
4. © Holst Centre 7
OLED Lighting / Signage OLED Display
• Price competitive against: incandescent • High prices for high-end
light bulb, fluorescent, non-organic led market (telephones, TV’S,
• Pursue pixels as big as possible for monitors)
more efficient light output • Pursue pixels as small as
possible for better
resolution
Large size flexible OLED for lighting/signage
OLED Display
Organic and printed electronics 23 Nov 2012
© Holst Centre 8
Why Flexible OLED?
• Rollable, wearable, ultra-thin, low-weight, unbreakable
• Easy integration in walls, ceilings, windows, cars etc.
• Light color can be tuned
• Enabling large area, low-cost R2R production
• GOAL:
R2R production for <100 €/m2 and 50 lm/W @ LT70=10kh in
2016 (light bulb 12 lm/W, fluorescent 55 lm/W)
In bodywork integrated OLED OLED for lighting/signage
Organic and printed electronics 23 Nov 2012
5. © Holst Centre 9
Why Flexible OLED?
“Hammer test” OLED
Organic and printed electronics 23 Nov 2012
Presentation
overview
OPV –Organic photo voltaic
Organic and printed electronics 23 Nov 2012
6. © Holst Centre
Solar power: omnipresent
Solar radiation on earth sphere
5,000,000 ExaJoule/year
Global energy
consumption circa
500 ExaJoule/Year
Organic and printed electronics 23 Nov 2012
© Holst Centre
Capturing 0,01%
covers total energy need
Requires 750.000 km2 present day solar
cells
(Surface area of Spain = 500.000 km2 )
Present world wide installation <200 km2
Organic and printed electronics 23 Nov 2012
7. © Holst Centre
Improving efficiencies
Source: NREL National renewable energy laboratory www.nrel.gov;
Organic and printed electronics 23 Nov 2012
© Holst Centre 14
Why Flexible OPV?
• Rollable, wearable, ultra-thin, low-weight, unbreakable
• Easy integration into walls, roofs, tents, mobile phones etc.
• No use of scares metals (Cd, Te, In, Ga, Se, As, Mo)
• Enabling large area, low-cost R2R production
• Goal:
R2R production for <50 €/m2 and >10% efficiency in 2016 (<0.5
€/Wp )
Roll to roll produced silver cathode Former generation OPV cells
Organic and printed electronics 23 Nov 2012
8. Presentation
overview
R2R manufacturing
Organic and printed electronics 23 Nov 2012
© Holst Centre 16
Lay out of the “bottom emissive“ OLED or OPV
stack
• Top Encapsulation to prevent water vapor / oxygen
• Cathode
• Functional layer 0,08-0,3µm
(human hair≈0,02-0,2µm)
OPV: PAL = Photon Absorbing Layer
OLED: LEL = Light Emitting Layer
• Anode
• Metal grid to support surface
power distribution/collection
• Moisture barrier prevent
water vapor / oxygen
• Foil = Transparent
Because of Ohms Law functional layer
should be:
• Homogeneous in film thickness
Schematic overview of OLED/OPV stack
Organic and printed electronics 23 Nov 2012
9. 17
© Holst Centre
17
Inspection Inspection Inspection
Example of Foil quality Particles Coating defects
Defects Layer thickness
Optical constants
manufacturing foil
process
substrate
production
Barrier deposition
half-
SiN/OCP/SiN product
Cleaning?
Cleaning? Repair?
Plasma Cleaning Inspection Inspection Inspection Inspection
surface energy Coating Coating defects Coating defects Coating defects
Inspection defects Layer thickness Layer thickness Layer thickness
particles Plasma
defects in barrier Cleaning
Repair
surface
energy
metal grid organic organic organic
(printing) layer I layer II layer n
Cleaning? Cleaning?
Inspection in dry and/or
wet layer?
Target processes for mass production:
Vacuum and/or non vacuum R2R / S2S Vacuum / N2 atmosphere
Inspection Inspection Inspection
electrical defects Coating defects device
Repair Layer thickness performance
Cost modeling clearly shows that R2R hard shorts
only is more efficient if:
Barrier deposition OLED
• Yield process step is very high(>95%) Cathode
(evaporation)
end-
SiN/OCP/SiN product
In situ monitoring a necessity
Inspection ?
• Homogeneity requirement of OLEDs Particle
(local)
contamination
favor slot die coating but patterning Cleaning? Cleaning? Repair?
in tiles not straight forward.
Organic and printed electronics 23 Nov 2012
© Holst Centre 18
R2R equipment for OLED or OPV manufacturing
Anode deposition +
Barrier Production Metal grid production Functional layers +
Cathode deposition
Roll to Roll barrier tool Roll to Roll flash sintering Roll to Roll coating line
- Length 6 meter, 33ton - Length 10 meters - Length 14 meters
- Width web 30-42 cm - Width web 30-40 cm - Width web 30-50 cm
- Speed 0,1-5m/min - Speed 1-20 m/min - Speed 3-30 m/min
- PECVD - Screen and inkjet printing - Slot die coating technology
- Organic/anorganic - Metal sintering by flash - Intensive air drying
deposition
- Cleanroom compatible - Cleanroom compatible
- Vacuum
Organic and printed electronics 23 Nov 2012
10. © Holst Centre 19
Roll to Roll coating line
Splice Re-winder
Un-winder
30-60cm wide
Corona
Surface- Schematic overview table 30-60cm wide
500mtr long treatment 500mtr long
Tacky roller for
Contamination Coating/print Hot Air Dryer Foil laminating unit
control Station 25-250°C
- Modular - 5000m3/hour
Stirring unit
Stirring unit
Organic and printed electronics 23 Nov 2012
Presentation
overview
Web Handling
Organic and printed electronics 23 Nov 2012
11. © Holst Centre 21
Roll to roll manufacturing:
Production of a device on a flexible carrier or substrate (web) by rolling off and on.
This is a very efficient way of production and transporting of large area
materials.
For R2R production you need of web handling.
Web handling: Art and science of getting a web through a machine as
fast/wide as possible with a minimum of waste.
Force is applied on a web to induce tension
Strain in tensioned
web
Stress-strain curve of Examples of E-
plastic web modelus
Organic and printed electronics 23 Nov 2012
© Holst Centre 22
Web handling
Why do we need tension with web handling
• Tensioning creates friction against rollers necessary for traction especially
in the winding roller
• Tensioning can pull out web bagginess. Every web has some amount of
cross web length variations.
• Accurate control of tensioning combined with speed control, sets the web's
mass flow rate.
Metal foil in R2R machine “Stripe coating” Web rewinder
Organic and printed electronics 23 Nov 2012
12. Presentation
overview
Slot die coating
Organic and printed electronics 23 Nov 2012
© Holst Centre 24
A coating liquid is forced out from a
Slot die coating reservoir through a slot die by pressure,
and transferred to a moving web.
The fluid dynamics inside the slot die
distribute the flow of the coating material
homogeneous over the full width of the
slot.
The wet layer thickness on the web is
solely depending on the material flow,
the width of the slot and the speed of the
web. Independent of material viscosity or
surface tension.
Schematic view of slot die coater
Slot die coater with vacuum box
Organic and printed electronics 23 Nov 2012
13. © Holst Centre 25
Slot die coating
Geometric parameters
Design variables of the coating die: shape, position, die lips, feed slot,
web, gap clearance, radius of application roll
Design variables define shape of slot die
Operating parameters
Web speed
Wet film thickness
External forces e.g. gravity
electric or magnetic fields
Gas pressure at upstream
and downstream menisci
Important parameters in slot coating flow experiment. L: lip
length, H: coating gap, W: slot gap, θs1: static contact angle,
θs2: separation angle, θd: dynamic contact angle.
Organic and printed electronics 23 Nov 2012
© Holst Centre 26
Slot die coating – geometric parameters
Because of Ohms Law the functional layers should be:
• Extreme homogeneous in thickness!
Slot die coater with vacuum box
Organic and printed electronics 23 Nov 2012
14. © Holst Centre 27
Slot die coating – fluid and material properties
Fluid and material properties
The wetting behavior of the coating
fluid on the web and the coating die.
The rheological properties of the
coating fluid
The surface tension
The density
Properties of substrate
Inhomogeneous coating because of
wetting problems!
Organic and printed electronics 23 Nov 2012
© Holst Centre 28
Slot die – OPV module
OPV Module
• To obtain sufficient voltage the individual cells
are serie connected in a solar module.
• The surface area ratio active zone/inactive
zone gives the module efficiency
Flexible OPV module
Cross section of the layer structure of an OPV module
Vtot ≈ 3xVcel
Active zone Inactieve zone
-OPV cell- serie connection
Organic and printed electronics 23 Nov 2012
15. © Holst Centre 29
Slot die - OPV module
Multiple-pass thin film slot die coating for stacking functional layers
Stripe coating a.k.a. R2R homogeneous patterning of thin film coating in
machine direction
Accurate 2mm shifted thin layer stack
Up to 5 layers
Slot die with shims for stripe Flexible OPV module
coating
Organic and printed electronics 23 Nov 2012
© Holst Centre 30
Slot die - OPV module
The surface tension at
the edges of a stripe
could differ a lot.
Dewetting, coffee stain
effects and rough edges
could occur!
Overview of surface tension at layer edges
Wetting envelope for coating material to predict wettability
Organic and printed electronics 23 Nov 2012
16. Presentation
overview
Contamination Control
Organic and printed electronics 23 Nov 2012
© Holst Centre 32
32
Particle defects in OLEDs.
Particle contamination during production causes fast degradation of OLEDS.
The contamination control should be an integral part of OLED
production.
Defects in OLED:
1. Fast growing in time: Barrier defect
2. Non growing: defect in active structure, covered by bulk cathode
3. Slow growing: defects in cathode covered by barrier
4 Barrier
Cathode 3 1
Light Emitting Layer 2
Anode
Schematic of some of the many particle defect that
could occur.
Organic and printed electronics 23 Nov 2012
17. © Holst Centre 33
Organic and printed electronics 23 Nov 2012
© Holst Centre
34
Toolbox for measuring particles
Particle card Particle roller Particle (SEM) probe Particle fall out box
Technique lower detection lower detection large area SEM Remark
limit size sampling possible
#/cm2 micron (> 100 cm2)
Particle card 0,5 2--3 no yes general use
Particle roller < 0,1 2--3 yes yes large area sampling
Particle probe 0,5 0,3 no yes identification on shape, size ..
Particle fall out box 0,01/(hour) 2--3 -- yes finding local sources
Q3-2012-SIF-TP1
18. Presentation
overview
Summery
Organic and printed electronics 23 Nov 2012
© Holst Centre 36
Summery
• There is a huge market for OLED for lighting if prices are made competitive
• OPV high potential if cell efficiencies go up or scares metals are unavailable
• R2R production is necessary for a competitive price
• The main challenge is to get a high production yield with many complex
production steps
• Functional layer homogeneity is very imported and difficult to obtain
• In-line OPV module production is easy to produce with slot die coating
• Contamination control should be integrated part of the production process
Organic and printed electronics 23 Nov 2012
19. Presentation
overview
Holst Centre – Large Area Printing
Organic and printed electronics 23 Nov 2012
© Holst Centre 38
Holst Centre Large Area Printing & Coating Program
The general goal of the Technical Program Large Area Printing, is to develop wet
deposition process technologies for R2R compatible application of patterned thin
and homogeneous layers of electro-active materials on flexible supports.
The electro-active materials currently envisaged in large area coating are mainly
used in OLED devices for lighting and signage and OPV modules.
The approach of large area coating program is generic, meaning that for possible
future new materials and applications, the technologies currently studied should
be (easily) adaptable to serve these new applications as well.
Some of the many prototypes made at the HOLST CENTRE.
Organic and printed electronics 23 Nov 2012