encapsulation of organic photonic elements · pdf file1 y. leterrier - swisslaser net...

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Y. Leterrier - SwissLaser Net Workshop, Basel, June 25, 2008

Encapsulation of Organic Photonic Elements

Y. LeterrierLaboratoire de Technologie des Composites et Polymères (LTC)

Ecole Polytechnique Fédérale de Lausanne (EFPL)CH-1015 Lausanne, Switzerland

SwissLaser Net Workshop, Basel, June 25, 2008


Polymers are (too) permeablePolymers are (too) permeable

Crank & Park, ‘Diffusion in polymers’ Academic Press (1968)Chatam, Surf. Coat. Technol. (1996)Pauly, in ‘Polymer Handbook’ Wiley (1999)

10-4

10-3

10-2

10-1

100

101

102

103

104

10-7 10-5 10-3 10-1 101 103

OT

R (

100 u

m;

cm

3/m

2/d

ay/b

ar)

WVTR (100 um; g/m2/day)

PP

LDPE

HDPE

LCP

Cellulose

PA6PET

PEN

PVDC

PC

PS

ABS

EVOH(dry)

EVOH(wet)

PAN

PVC

OLEDdisplays

Solarmodules

Foodproducts

2


Polymersubstrate

Inorganic film(10-1000 nm)

BIF ~ 100

BIF ~ 1’000

BIF > 105

BIF ?

Barrier Improvement Factor: BIF = Ps/P

nanolaminates

Organic-inorganic hybrids

High-Barrier StrategiesHigh-Barrier Strategies


h

P=hc

Pc

+hs

Ps

Coatingpermeability Pc, thickness hc

Substratepermeability Ps, thickness hs

Nanosized Nanosized inorganic coatings/polymer compositesinorganic coatings/polymer composites

OTR

(cm

3 /day

/m2/

bar)

Coating thickness (nm)0.1

1

10

100

1000

0 100 200 300 400 500

PECVD

Evaporation

Sputtering

PET

AlOx

Aluminized PET

SiOx/PET films

Leterrier, Prog. Mater. Sci (2003)

3


Defects in vapor-deposited inorganic films on polymersDefects in vapor-deposited inorganic films on polymers

Roberts et al., J. Membrane Sci. (2002)Rochat, Leterrier, Månson, Fayet, Surf. Coat Technol. (2003, 2006)

Defectdependentpermeation

Critical coatingthickness ranges

between 8 and 15 nm

Courtesy Tetra Pak

3.10 3.15 3.20 3.25 3.30 3.35 3.40 3.45 3.50-24

-23

-22

-21

-20

-19

-18

-17

-16

-15

Temp (1/

OK) x 10

3

ln P

Ep (PET)

= 32.4±1.3 KJ/mole

Ep (SiOx_PET)

= 34.4 ± 2.1 KJ/mole

SiOx/PET


10 nm SiOx on PET @ 10% strain

Effect of coating defects on failure of barrierEffect of coating defects on failure of barrier

Rochat, Leterrier et al., J. Appl. Phys. (2003)Singh, Leterrier, Månson, Fayet, Surf. Coat. Technol. (2007)

1 µm

0

100

200

300

400

500

600

0

20

40

60

80

100

120

0 0.02 0.04 0.06 0.08 0.1

Cra

ck d

en

sit

y [

mm

-1]

Oxyg

en

tra

nsm

issio

n r

ate

[cm

3/m

2/d

ay/b

ar]

Strain

10 nm

50 nm

4


Polymersubstrate


BIF ~ 100

BIF ~ 1’000

BIF > 105

BIF ?


nanolaminates




Why Why nanolaminate nanolaminate structures?structures?

BIF > 105

Nanolaminates decouple defect structure

WVTR (20°C) ~ 2·10-6 g/m2/day(Vitex Systems, CA)

Trophsa & Harvey, J. Phys. Chem. B (1997)

5


Trophsa & Harvey, J. Phys. Chem. B (1997)Schaepkens et al., J. Vac. Sci. Technol (2004)

Modeling of gas transportModeling of gas transport

Barrier improvement obtained when adding a second inorganic layer


-8.6 × 10-6‘5’[SiNx/SiOx]nGE (graded UHB)

~ 1 × 10-5

3.6 × 10-6

~ 1 × 10-6

W V T R(g.m-2.day)

1.04(SiN/lacquer)2Applied Materials

1.0‘12’ + topcoat[SiNx/SiOx]nPhilips (NONON)

0.810[acrylate/Al2O3]nVitex (Barix)

Crack OnsetStrain (%)

Number of layersEncapsulationStructure

Producer

Nanolaminate Nanolaminate encapsulationencapsulation

6


Polymersubstrate


BIF ~ 100

BIF ~ 1’000

BIF > 105

BIF ?


nanolaminates




Why organic-inorganic hybrids?Why organic-inorganic hybrids?

Pluddemann, Silane Coupling Agents, Plenum Press (1990) Zinck et al., J. Mater. Sci. (1999).Haas et al., Surf. Coat. Technol. (1999)Bouchet et al., Surf. Coat Technol. (2005)

Substrate

Coating

Flaw

Highlycrosslinked

region

Chemisorbedlayers

Physisorbedlayers

Organo-silanes reduce the severity of superficial defects (‘Griffith flaws’)

R—Si—(OR’)3

7


NH2 Si(OC2H5)3

Gamma-aminopropyltriethoxysilane(γ-APS, Silquest A-1100TM)

1 - 20 %wt γ-APS/ethanolpH=11.4 and pH=8 (acetic acid)

oligomerization: 12 h at 60°C10 - 500 nm thick silane films

Spin coating on SiOx/PET films1000 rpm, 20 s

Magni et al, J. Phys. D (2001)Bouchet, Leterrier et al., Surf. Coat. Technol. (2005, 2007)

SiOx 12 nm PECVD from O2 dilutedHMDSO on 12 µm thick PET web

OTR ~ 2.1 cm3/m2/day/barCOS ~ 3.5%

Processing of Processing of organosilane-silica organosilane-silica hybridshybrids


Amino-silane treatmentreduces the size and

population of macro-defects

SiOx/PET RIE 12 min.Average defect radius 720 nm

γ-APS/SiOx/PET RIE 12 min.Average defect radius 330 nm

Singh, Leterrier et al., Surf. Coat. Technol. (2007)

Defect analysis in Defect analysis in organosilane-silica organosilane-silica hybridshybrids

8


Crack onset strain > 6%

Rochat et al. Thin Solid Films (2003)

Crack onset strain 3.5%

Mechanical integrity of Mechanical integrity of organosilane-silica organosilane-silica hybridshybrids

γ-APS/SiOx/PET

5 µm12%

5 µm20%

5 µm10%

0% 5 µm

10 nm SiOx/PET reference

0% 5 µm


Supertough Supertough high barrier high barrier encapsulationencapsulation

Supertough high barrier encapsulation

BIF > 105

nanolaminates Organic-inorganic hybrids

COS ~ 5%

Stress state?Microcracking?

9


Origin of stress in polymer coatingsOrigin of stress in polymer coatings

!(t) = 2 G(t)"c

"t0

t

# dt + 2 G($s+

Tc

Tf

#"c

"T)dT

Cureshrinkage

stress

Thermal stress(small for UV-

curable polymers)

Lange, Månson et al., Polymer (1995, 1997); Payne (1998)

… Lack of dimensional stability

… Void formation?

… Buckling and cracking


Towards low stress encapsulationTowards low stress encapsulation

Tailored processtemperature cycles

‘Low profile’ additives Radiation curing… Hyperbranched polymers

A low-stress material combines:

reduced shrinkage⇒ radiation curing

retarded modulus build-up⇒ hyperbranched polymers

10


Tg: 68°C Tg: 126°C

Tg: 28°C

Photoinitiators:1-Hydroxy-cyclohexyl-phenyl-ketone1:1 blend of 1-Hydroxy-cyclohexyl-phenyl-ketone and benzophenone

HBP + 5 vol% SiO2

100 nm

HBP + 20 vol% SiO2

100 nm

Low Stress UV Curable Low Stress UV Curable Hyperbranched Hyperbranched Polymer Polymer NanocompositesNanocomposites


Microbattery, layer thickness 500 µm

3

0.5

0.5

Fabricationtime(h)

372511250SU-8

7334.53.3500Polyester HBP

54542.47.7850Polyether HBP

FOMResidualstress(MPa)

Aspectratio, AR

Layerthickness, L

(µm)

Resist

SU8Polyether HBP

FOM = (L x AR) / (Stress x Fab_Time)

Jin Y.-H., J. Micromech. Microeng., 17, 1147-1153 (2007).Schmidt et al., J. Micromech. Microeng. 18, 045022 (2008).

Low Stress UV Curable Low Stress UV Curable Hyperbranched Hyperbranched Polymer Polymer NanocompositesNanocomposites

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Polymersubstrate


BIF ~ 100COS ~ 2%

BIF > 105

COS ~ 1%


nanolaminates



BIF ~ 1000COS ~ 2%

BIF ~ 1000COS ~ 5%


AcknowledgementsAcknowledgements

• F. Demarco, G. Rochat, B. Singh, J. Bouchet, J.-A. Månson, LTC-EPFL• Dr. J. Andersons, Inst. Polymer Mechanics, Riga (LV)• Dr. Y.-H. Jin, Pr. YH Cho, KAIST (KR)• Dr. P. Bouten, Philips Research Laboratories (NL)• Dr. N. Rutherford, Vitex Systems (USA)• Dr. D. James, Dr. S. Lundmark, Perstorp SC (S)• Dr. P. Fayet, Tetra Pak Suisse SA, Plasma Technology (CH)• Centre Interfacultaire de Microscopie Electronique (CIME-EPFL)• Centre de Micro-Nano-Technologies (CMI-EPFL)• Swiss Commission for Technology and Innovation (CTI) and the Top Nano 21 Swiss

initiative (TNS 5940.2)• Swiss National Science Foundation (SNF 200020-111706)• Swiss Federal Office for Education and Science (OFES - IST-2001-34215)• FLEXIDIS (EU-IST 2004-4354)

THANK YOU!

encapsulation of organic photonic elements · pdf file1 y. leterrier - swisslaser net...

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