The document discusses research on smart materials for conformable electronics and photonics being conducted by Holst Centre. Holst Centre is an independent research organization co-founded by IMEC and TNO that focuses on creating generic technologies for flexible electronics. The presentation provides an overview of Holst Centre's work on organic light-emitting diodes (OLEDs) including applications, lifetime considerations, conformable technology approaches, and a vision for conformable electronic and photonic systems featuring wearable and stretchable designs.

2. November 27, 2012
Smart Materials for
Conformable Electronics
and Photonics
Margreet de Kok
Holst Centre
Mikrocentrum 23 november 2012

3. 10 november 2011
Presentation
overview
Contents
1. Holst Centre
2. Introduction OLED
3. Application of OLED
4. Lifetime of OLEDs
5. Conformable technology
6. Conclusions

4. © Holst Centre 4
Holst Centre Fingerprint
Who we are
Independent research organization co-founded by IMEC (1300 fte,
Belgium) and TNO (4500 fte, the Netherlands) in 2005
Global network of industrial and academic partners
150 researchers and 60 resident researchers from industry and university
What we do
Creating generic technologies, time to market 3..10 years
Research Focus on wireless, autonomous micro-systems
and flexible electronics
How we work
Open Innovation through precompetitive research programs
Roadmaps defined along with partners
Day to day interaction with industrial residents
Results are shared between partners

5. © Holst Centre 5
Large Area Electronics market applications
Flexible displays
Plastic solar cells
Touch screens
Plastic batteries
Smart
packaging Signage
RFID tags
OLEDs
Sensors
Disposable bio-sensors
Smart bandage
Electronic textiles

6. © Holst Centre 6
Important Enabler:
Organic Semiconductors
New ways of MicroDrop
processing Inkjet printing
Soluble Semiconductors
Roll to Roll coating

7. © Holst Centre 7
Access to Unique Set of Infrastructures and Process Labs
High Tech Campus, Eindhoven
Amsterdam
Netherlands
Eindhoven
Düsseldorf
Aachen
Leuven
Belgium

8. © Holst Centre
Industrial partners from across the value chain

9. 10 november 2011
Contents
1.Holst Centre
2.Introduction OLED
3.Application of OLED
4.Lifetime of OLEDs
5.Conformable technology
6.Conclusions

10. © Holst Centre 10
OLED Basics
Two types of OLEDs:
cathode
Organic layers
anode
Polymer LED
Small molecule LED

11. © Holst Centre 11
OLED: Electroluminescence
(Fluorescent emitter)
Typical Light Emitting Polymers:
PPV (polyphenylene vinylene)
PF (polyfluorene)

12. © Holst Centre 12
OLED: Injection scheme
SrO
BaO
Cs
LiF GdB6 2
Ba Li,K
Work function (eV)
Ca TiN
3
Mg
Hf
4 In 4
Al
Ag
5 PEDOTNi Au
ITO
Pt
Se TiO
6
2
High workfunction Low workfunction
anode materials cathode materials

13. © Holst Centre 13
IVL
• Vbi ~Vturnon 10000
BL102
• Dependent on band gap material 1000
• Dependent on work function 100
10
difference of the contacts
J (A/m )
2
1
0.1
• Blue and white 20- 50 lum/W 0.01
1E-3
• Record: 100 lum/W
1E-4
-2 0 2 4 6 8
Bias (V)
2
BL102
Ba/Al
LUMOPF (2.2 eV) (2.7 eV)
PEDOT:
Efficacy (lm/W)
PSS
1
(5.1 eV) HOMOHT (5.2 eV)
0
-2 0 2 4 6 8 Energies with respect to the vacuum
Bias (V)
level

14. © Holst Centre 14
Application in OLED
144 cm2 white PLED without ITO using high conductivity PEDOT with
Ag printed shunting lines
AGFA

15. 10 november 2011
Contents
1.Holst Centre
2.Introduction OLED
3.Application of OLED
4.Lifetime of OLEDs
5.Conformable technology
6.Conclusions

16. © Holst Centre 16
OLED Applications & Expectations
Signaling Signage
Lighting
Displays

17. © Holst Centre 17
But also:
Company logo Automotive Healthcare
Add-Vision
Advertising
Automotive

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Flexible OLEDs
• Only prototypes, no commercial products
Add-Vision
Sony
Samsung
Novaled/Assilor-Mital
UDC
GE
• Showstopper: barrier films

19. © Holst Centre 19
Next Application for OLED: Solid State Lighting
LED
(SM/P)OLED

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Solid State Lighting
Small-molecular
Inorganic
Organic Macromolecular
OSRAM

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Comparison Inorganic – Organic LEDs
• Inorganic LEDs • Organic LEDs
• Products on the market with • First lighting products on
high efficiency and long the market
lifetime • Large area possible and
• Small area and high therefore low luminance
luminance (no large area enough
possible) • Thin
• Thermal management needs • Thermal management less
attention problematic
• (Colour stability of • Colour better controllable
production leads to binning • Cost per area effective
of LEDs)
Application and design freedom (and price) make the difference

22. © Holst Centre 22
Organic light sources and detectors:
opportunities and challenges
• Form freedom
• Large area possible
• Flexibility (bendability)
• Very thin features
• Fine tuning of optical properties possible
• Integration with multiple functionalities possible in foil
• Production technology versatile
• Cost aspect positive
• Challenges:
• Processing thin layers - shorts
• Encapsulation and intrinsic lifetime
• Efficiency
• Current density distribution
• Design of combination of building blocks

23. © Holst Centre 23
Why flexible?
• Enhanced functionality for the end user: bendable, rollable devices
But also
• Integration of foil devices in products & systems: conformal application?;
convenient feeding into assembly system
• Efficient large area production of foil devices (e.g. roll-to-roll; no manual
assembly) -> cost aspect
Source: GE Source: Metsuo

24. © Holst Centre 24
State-of-the-art in white OLED

25. © Holst Centre 25
OLED Trends
Materials
Substrates: flexible plastic or metal substrates combined with R2R processing
Barrier: strong focus on developing flexible thin film barriers (Holst Centre, Vitex,
General Electrics, Dow, ..) with WVTR < 10-6 g/m2.day
Emitters: phosphorescent emitters (UDC, Sumation, Merck, Novaled, ..)
Transport layers: doping of transport layers (Novaled, ..)
Cathodes: top emitting/transparent OLEDs with transparent cathodes
Anodes: high conductive organic materials and/or or introduction of support
structures (evaporated or other) (GE, OLLA, Holst Centre, ..)
Processing:
Roll-to-roll processing on flexible plastic or metallic substrates
Printing or coating of functional materials in general (as opposed to spin-coating)
Printing or coating of small molecules (Dupont, UDC, ..)
Devices:
Innovative OLED designs / Intelligent Lighting
>100 cm2 lighting tiles (Lumiotec, GE, Philips, OSRAM, UDC, Konica Minolta, ..)
OLED display driving: AMOLED as opposed to PMOLED (SDI, LGE, SONY, ..)
TFT towards oxide TFT as opposed to OTFT / LTPS (Dai Nippon Printing)
Place-it: conformable electronic systems comprising OLEDs

26. 10 november 2011
Contents
1.Holst Centre
2.Introduction OLED
3.Application of OLED
4.Lifetime of OLEDs
5.Conformable technology
6.Conclusions

27. © Holst Centre 27
OLED Degradation

28. © Holst Centre 28
OLED Degradation

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OLED Degradation: black spots
• Intrinsic: homogeneous degradation
• Cathode oxidation: local degradation leading to black spots
H2O, not O2
Right after processing ~10h at 20 °C / 50% RH

30. © Holst Centre 30
Standard Encapsulation
State-of-the-art encapsulation using metal or glass lid with cavity
containing getters
no hermetic seal (getter!)
40,000 hrs at 80 °C without black spot formation
cathode getter
organics
ITO
substrate
But, it is not applicable for:
Fast production
Large area devices
Flexible (foil-based) devices

31. © Holst Centre 31
Requirements for (TF) barrier/encapsulation
• Intrinsic WVTR < 10-6 g.m-2.day-1
• No black spots
>5 years @ 20/50
>504 h @ 60/90
• Feasibility for R2R
Barriers should be rollable over d=20cm
• Low cost
High deposition rates
Barrier on foil specific:
• Transparency for visible light >90%
• Uniform light output
Extremely uniform layers over large areas
• Light outcoupling
• Abrasion resistance, UV protection, etc.

32. © Holst Centre 32
Multilayer approach
• Stacks of inorganic and organic layer used to decouple pinholes
and get full coverage => time delay of black spot formation
• Holst approach: SiN – OCP – SiN
• OCP = organic coating for planarisation
100
SiN
SiN-org-SiN planarization
black spot area (a.u.)
10
4 layer
3
1
1 2
0.1
10 100 1000 10000
time (hrs)

33. © Holst Centre 33
State of the Art for encapsulation
• Wvtr: 10-6 g/m2day
• >5000 hrs at 20/50 black spot free and still running
Side leakage Black spots by pin holes

34. © Holst Centre 34
Advanced systems by combined functionalities in Foil
• Organic LEDs
• Organic Photodetectors
• Organic Photovoltaics
• Embedded circuitry
• Embedded chips
• RFID
• Memories
• Sensors
Electrochemical
Optochemical
Optical

35. © Holst Centre 35 35
Device Design - laminated foil approach
• Foil
Double side processing
Modular: diodes and LEDs printed on separate foils
• Top emissive PLEDs, Bottom receptive OPDs:
Photodiode
skin
LED
• Bottom emissive PLEDs, Top receptive OPDs:
skin
30
Spectral Radiance (10 W/sr m nm)
2
25
20
-3
• Etc. 15
10
5
0
500 550 600 650 700 750
wavelength (nm)

36. © Holst Centre 36 36
Printed devices
• Foil
Single side processing
Diodes and OLEDs via printing
Arrays of different devices on one substrate

37. © Holst Centre 37 37
Foil Integration
• Modular approach
• Distribute functions over
different layers µ-via
technology combined with
lamination
• Silicon in Foil embedding

38. © Holst Centre 38 38
First Organic Device Prototype: Proof of Principle
• OPD • Works!
Total measured current PPG comparable to commercial
ca. 10 µA pulse-oximeter (Nelcor N200)
Signal ca. 50 nA
• PLED
I = 80 mA/cm2
V = 5.2 V
L = 520 Cd/m2
Signal (a.u.)
Organic
Nelcor N200
0 1 2 3 4 5
Time (s)

39. 10 november 2011
Contents
1.Holst Centre
2.Introduction OLED
3.Application of OLED
4.Lifetime of OLEDs
5.Conformable technology
6.Conclusions

40. © Holst Centre 40
Rigid –> flexible -> conformable
Glass based OLED Flexible OLED
Philips Lighting Holst Centre

41. © Holst Centre
The vision: conformable electronic and photonic
systems
• Featuring
Conformable, stretchable/flexible
Thin and light weight
Unobtrusive integration
Wearable
• Applications:
Biomedical (sensors, phototherapy)
Textile/fashion,
Outdoor (biking, road safety)
Architecture
Displays
Interior design (curtains, furniture)
• Advantages organics c.t. inorganics:
Large area: homogeneity
Very thin
Temperature management
Combination inspiring
Margreet de Kok Holst Centre 2011 august SPIE
41

42. © Holst Centre
Applications for wearable electronics & photonics
furniture
conformable
foil – textile
technology
Camouflage for defense Light therapy
Safety on the road
Textile for fashion
and safety
42

43. © Holst Centre 43
Healing power of sunlight: wearable phototherapy
TBC treatment by sun therapy

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Example - jaundice treatment of neonatals
• Old treatment
Static light sources necessitating eye protection of neonatal
Jaundice treatment: photochemical conversion and excretion of
bilirubine (yellow colour treatment)
• New possibility
Wearable light source
less interfering with care
including bonding with parents
Philips BilitXTM
Source flickr: 1542122226_5e43a1d008 and 2538039854_e67b67926c Blue LED based

45. © Holst Centre 45
Other options for applications
• Light in safety (traffic, working conditions)
• Light harvesting (tents, outdoor sports, clothing)
• Phototherapy:
psoriasis,
eczema,
jaundice,
wound healing,
prevention decubitus,
pain relief,
skin rejuvenation
• Camouflage
• Textile design – fashion!
• Bring light where no light was before

46. © Holst Centre
Conformability by segmented approach
46

47. © Holst Centre 47
Conformable electronics
T. Sekitani, T. Someya et al. Nature Materials 8, 2009 p. 494-499
R. Kim, J. Rogers, et al. Nature Materials 9, 2010, p. 929-937

48. © Holst Centre 48
Stretchable systems
• OLED structuring on rigid regions: printing technology
• OLED / OPV need protection by barrier technology
• Interspaces deliver stretchability and should contain electric
circuitry: Ag nanoparticles in binder matrix
pedot LEP Ba/Al
foil
anode cathode
pedot Ba/Al
Top barrier
Bottom barrier
foil
anode cathode

49. © Holst Centre 49
Structured deposition of active materials
• Printing:
Inkjetable ink formulation (halogen-free solvent): droplet formation
Jetting and stable in time & speed
Ink & substrate interaction
Layer formation and homogeneity
Device performance and efficiency

50. © Holst Centre 50
Ink & substrate interaction
• Pinning and de-wetting
Plasma
treatment
Temperature
treatment

51. © Holst Centre 51
Solvents selective layer formation
A 100% A:B=50:50 B 100%

52. © Holst Centre 52
Inkjet printed OLED active layer development
2007
2011

53. © Holst Centre 53
State of the art

54. © Holst Centre
Level of integration into textile for wearable
systems
• Textile:
In textile as fiber
Onto textile by conductive yarns to electronics
Iron on self contained system
Fibers Fabrics Product
54

55. © Holst Centre
CIMTEC 2012 M. de Kok
55

56. © Holst Centre 56
Stencil printing of ICA

57. © Holst Centre 57
Bonded OLED onto textile

58. © Holst Centre
Foil components on textile
58

59. © Holst Centre
Stretchable systems in rubber (meander)
• Light homogeneity
• Bare die for reduced
thickness
• Density of elements
• Thermal management
Frederick Bossuyt Holst Centre / imec Gent
59

60. © Holst Centre 60
Platform for Large Area
Conformable Electronics
by InTegration
FP7 Place-it
60

61. 10 november 2011
Contents
1.Holst Centre
2.Introduction OLED
3.Application of OLED
4.Lifetime of OLEDs
5.Conformable technology
6.Conclusions

62. © Holst Centre 62
Conclusions
• Organic electronics on textile have a bright future
• Technology development indispensable
• Collaboration between disciplines necessary
• Conformable electronics will change the world
• Margreet.dekok@tno.nl
• www.holstcentre.com
• Thank you for your attention

63. Visit us at
www.holstcentre.com