Dispensable Getter Materials for lifetime insurance in...

Dispensable Getter Materials for lifetime insurance in Organic Electronics

Paolo Vacca,

w e support your innovation

Paolo Vacca,

Roberto Giannantonio, Antonio Bonucci, Stefano Zilio, Stefano Tominetti

SAES Getters

"ORGANIC ELECTRONICS : principles, devices and applications“Politecnico di Milano – November 18, 2011

Outline

� Overview of the SAES Group

� Organic device degradation

� Encapsulation lay-out

� A new family of Dispensable Getter Materials



� Conclusions

2 SAES Getters S.p.A.

Overview of the SAES Group


1947 SAES, Società Apparecchi Elettrici e Scientifici based in Milan (Italy), becomes operative through investments by families della Porta and Canale.


Overview of the SAES GroupSAES core business

The SAES® Getters Group develops technologies and products addressing a variety of scientific and industrial applications needing:

� high vacuum� pure metals evaporation� ultra-high pure gases

w e support your innovation4 SAES Getters S.p.A.

A Customer-focused approach

Nearly 3,000 active customers in 5 continents, spanning from universities and research centers to business start-ups and blue chip companies

High flexibility in product development, fine-tuning and manufacturing, to foster emerging and forefront application technologies


blue chip companies technologies

70 years of expertise in partnering with customers for the engineering of fully customized solutions

Technical service network and CRM structure supporting customers’ innovation24 hours a day


Corporate Headquarters

� Management of the Group

� Corporate R&I laboratories

� Corporate functions

Milan-area Headquarters


� Corporate functions

� Technical support


Global Presence


Research & Innovation


� About 12% of net consolidated sales allocated to R&I activities every year

� State-of-the-art corporate laboratories covering a surface of over 3,300sq. m.

� Nearly 80 people committed to investigating problems, developingproposals and testing solutions


Outline







� Conclusions


0,8

1,0 450

482

Intensity [a.u.]

12V

420

OLED OLED degradation


350 400 450 500 550 600 650

0,0

0,2

0,4

0,6

wavelength [nm]

Intensity [a.u.]

12V 11V 9V

PhD Thesis “TECHNOLOGY AND ELECTRO-OPTICAL CHARACTERIZATION ON ORGANIC SEMICONDUCTOR DEVICES” P. Vacca


Organic Electronic Devices degradation phenomena

H2O, O2contamination

Extrinsic

External contamination

Intrinsic

Inter-diffusion

Material changes

Material blending

EvolutionEvolution

MechanismMechanism


During shelf life During operation During operation

Dark spots Pixel shrinkage

Dark spots Short circuits

Luminance decrease

Anisotropic Anisotropic Isotropic

EvolutionEvolution

DefectsDefects

UniformityUniformity


Organic Electronic Devices degradation phenomena


In order to limit dark spot area growth and pixel shrinkage below values significantly affecting the display uniformity: maximum H2O pressure inside OLEDs ~ 1.1x10-4 Torr or ~ 0.1 ppm


Outline







� Conclusions


Permeation fronts in inefficient encapsulation package

glass sheet

Barrier sealant

d� Interfaces


glass substrate

anode

cathode

dInterfaces

� Barrier bulk

� Organic EL layers


Barrier properties of some coatings

10-2

100

102

sensitive food products

oxy

gen

tra

nsm

issi

on

rat

e (c

m3 /m

2 d)

LCD LED


10-6 10-4 10-2 100 10210-6

10-4

10-2

OLED displays, organic solar cells

oxy

gen

tra

nsm

issi

on

rat

e

Water vapour transmission rate (g/m2 d)


Encapsulation package optimization (1): lay-out

glass sheet

2. Barrier sealant : SAES active barrier


glass substrate

anode

cathode

1. Patterned Organic EL layers

l


Encapsulation lay-out

Barrier sealantIncreased lag time can be achieved by increasing l (1-2mm) and

Organic ELPatterned layer to reduce the penetration front


Increased lag time can be achieved by increasing l (1-2mm) andby decreasing h (up to 5-10 µm scale)

h


Encapsulation package optimization (1): improved interfaces

� filler size

� filler surf.-mod.

Drop surface

tension

- fVS ; + fLV� non-wetting

Increasing


� filler surf.-mod.

� matrix polarity

� filler content

� viscosity

Drop surface

tension

Substrate surface energy

+ fVS ; - fLV� good wettability

Increasingpaste polarity


Dispensing quality depends on viscosity which is affected by:

o molecular weight of organic matrixo nature and amount of filler contento nature and amount of scavenger contento filler and scavenger particle size distributiono scavenger surface modification

Viscosity modulation


Particle size distribution effect

Surface modification effect


Jet dispensing

Jetting fluid dispensing technology is gaining popularity in the manufacture of Flat Panel Displays (FPD) due to increased throughput, improved yields, and simpler setup.

o jets in tight spaces as small as 175 µmo small fillet sizes as small as 300 µmo dot diameter as small as 200 µm


o dot diameter as small as 200 µmo shot volumes as small as 1.0 nanoliters

o jet stream size as small as 50 µm

o jets fluids from 1 to 250,000 mPa


Jet dispensing

Shear rate related to the

The key element of a jet dispensing system is a valve that meters and ejects fluid droplets: gas pressure retracts an internal spring-driven plunger, allowing a precise amount of fluid from the reservoir to enter the chamber under pressure. The spring-driven plunger then returns to its seat, ejecting the fluid as a droplet though the nozzle.


� Shear rate related to the ejecting process: 102-104 s-1

With non-Newtonian fluids like dispensable scavengers, viscosity decreases with increasing shear rate.

The paste must have the ability to restructure and recover its viscosity as soon as it reaches the substrate (thixotropy).


Thixotropy for improving scavengers processability

1,0E+03

1,0E+04

shear stress (Pa

)


1,0E+00

1,0E+01

1,0E+02

1,0E-03 1,0E-02 1,0E-01 1,0E+00 1,0E+01 1,0E+02 1,0E+03 1,0E+04

shear stress (Pa

)

shear rate (s-1)

thixotropic


Molecular weight impact on jet dispensing

� Drop break-up is strongly related to the polymer molecular weight.


Molecular weight much too high


ODF process for optimized encapsulation


ODF process for optimized encapsulation

Process step:• Coated glass is placed on the substrate mask into the chamber• Cover glass is held by the clamp device (chuck) on the cover of the UV-press• The system is evacuated to the process-pressure value (10-2 mbar)• The two glasses are put in contact• System pressure is equalized to the atmospheric pressure• The UV-lamp irradiate the sample


• The UV-lamp irradiate the sample• The encapsulated sample can be removed


Outline







� Conclusions


The concept of Lag time

Slope = WVTR

Typical permeation curveof a sealed system

Moisture concentration

w e support your innovationBreakthrough time

Lag time

Moisture concentration increases rapidly, even with a “good” WVTR.

Therefore, a desiccant is needed.


Getter technologiesdefinition of getter

� Gases can be captured through GETTER materials

� Capture = adsorption, dissolution, chemical reaction

� Specific feature of a GETTER material: capture kinetics is very fast, at the

given operating temperature, even if the gaseous species are highly rarefied

(highly diluted)


� capture is either irreversible

G + g G�g×

� or reversible

G + g G�g


Getter integration in OLED devices: modeling

Once moisture sources are identified, moisture distribution within a device depends on geometry and placement of the desiccant

Moisture ingress can be determined for a variety of structures, and equations set in place to model


Example:

30*40 mm2 OLED

2 25*14 mm2 DryFlex®

Test condition:

T=60 ° CRH=90%


Hybrid organic-inorganic gettersL �� L �� S

L L S


� surface properties� rheological properties� curing properties

deposition processes

� functional properties

solidification processes


Degradation of Organic Electronic Devices dispensable dryers (hybrid getters)

anode

glass sheet

getter filmgetter filmgetter filmgetter filmreactive edge sealantreactive edge sealantreactive edge sealantreactive edge sealant

d

anode

glass sheet

reactive fillerreactive fillerreactive fillerreactive filler

d


glass substrateanode

cathode organic EL layer

glass substrate

cathode organic EL layer

BOTTOM EMISSIONBOTTOM EMISSIONBOTTOM EMISSIONBOTTOM EMISSION TOP EMISSIONTOP EMISSIONTOP EMISSIONTOP EMISSION

Formulation Dispensing Curing Solid coating


Hybrid organic-inorganic gettersL �� L �� S

Non transparent Transparent

Nano-ZeolitesOxide systems Other chemistry

Organic Electronics

DisplaysPlastic ElectronicsSolar Cells

Thermal / UV Curing Thermal / UV Curing

T i

m e

L

i n e


Thermal Curing

Active Barriers

Thermal / UV Curing Thermal / UV Curing

DryPaste ®Glue

Gel

Paste

Polymer systemsT

i m

e

L i n

e


SAES approach

Polymerization

Step polymerization

Polyaddition (hydrosilylation)

Polymer begins

• Controlled reactivity

• No by-products

• Gel-elastomer polymers with lower cross-link density

APPLICATION

FILLER

with high dispersingproperties


Polymerization process

Chain Polymerization

Radical polymerization

Cationic polymerization

• Polymer begins to form immediately

• Chain growth is very rapid under low UV dose

i) UV curable filler (low dose)

ii) thermal curablefiller (low temp.)

UV curable edgesealant

• UV curing under high energy dose

• better properties like adhesiveness


Consolidation mechanism

Polymerization

Step polymerization


Polymer begins


• No by-products


APPLICATION

FILLER















Hydrosilylation reaction for gel scavenger production

Filler

� Gels are solids featuring fluid characteristics� A filler gel provides mechanical protection and high instantaneous

deformation� Dampening with good cohesion assures high dryer loading


FILLER

OLED Stack

Filler


DryPaste1-Ga gel filler for OLED devices

Aluminum cathodeOLED in bottom emission configuration


Organic stackDryPaste-G in direct contact with stack and cathode


1This material and its associated products are covered by a PCT patent application deposited by SAES Getters S.p.A.; DryPaste is a registered trademark by SAES Getters S.p.A.


Ethylenically unsaturated polydiorganosyloxanes can be cured by addition reaction where the curing agent for a organosilicon mixture is an organo-hydrogensiloxane containing an average of more than two silicon bonded hydrogen atoms per molecule.


Working on cross-link density, it is possible to induce gel-like or elastomeric characteristics.


DryPaste-G

� DryPaste-G is a solventless dispersion of a chemical dryer in a siliconic matrix.

� It can be used as a film (10-500 µm) or as a patterned desiccant.� It is supplied in syringes sealed under protected atmosphere.� Mixing is not necessary.� Deposition can be performed by syringe, screen printing and blading


� Deposition can be performed by syringe, screen printing and blading (40.000-50.000 cP @ shear rate 45s-1 ).

� Deposition can be carried out in air.� DryPaste-G can also be used on flexible substrates.� Thermal curing (120°C for 3h) also possible (gel � solid).


DryPaste flow curve at 25 °C

1000000

10000000

Substrate C.A.glass 72.6 ± 3.6EVA 73.8 ± 2.7PET 70.0 ± 2.3


0.01 0.10 1.00 10.00 100.00 1000.00

Á in 1/s

10000

100000ƒ in

mP

as

HAAKE RheoWin 4.10.0007


DryPaste-G

Opening

IN AIR OR DRY GAS

DryPaste-G Process Flow

Device sealing

IN GLOVE BOX


Deposition

DryPaste-Guncured film

Curing DryPaste-G film

120 oC x 3 hours or 160 oC x 1 hour


DryPaste-G: thermal stability

The weight loss in dry nitrogen flux is < 0,2%wt during thermal treatment at 120 °C for 5h.


The cured DryPaste-G film is stable up to 185 °C in dry nitrogen flux, weight loss at 240 °C is <1%. No weight loss is observed before 185 °C.


DryPaste-G sorption performance at 25 oC / 55% RH

Curing at 160 oC x 1 h under nitrogen


DryPaste-G performance(after an exposure time of 3 hours at 25 oC / 55% RH conditions)

Sorption capacity after 3 hours exposure


Sorption capacity after 3 hours exposure in clean room air @ RT: > 10% wt


Optimized composition to tune moisture sorption kinetics

LMEAN=360 µmunsaturated

1 week at 85 oC / 85% RH


ABS range (absorbance)

completely saturated

Red-completely saturatedBlue-unsaturated


Ageing at 85 oC / 85% RH

330hLMEAN=400 µµµµm

670hLMEAN=700µµµµm

170hLMEAN=180 µµµµm



Polymerization

Step polymerization


Polymer begins


• No by-products


APPLICATION

FILLER















Low energy dose for transparent dryer

� Transparent dryer is applied in direct contact with the organic stack� UV curing of transparent dryer involves OLED stack exposure � Strong constraint for low energy dose has to be considered in order to

avoid OLED degradation� A low-energy polymerization process has to be selected


Transparent Dryer in FILLER configuration

OLED Stack

Filler



Every step is essential for the modelling and optimization of produced polymer matrix

1. Initiation


auto-acceleration

4. Chain-transfer

2. Propagation

3. Termination

Initiation needs very low energy


w e support your innovation49 Copyright IMID ’09 & SAES Getters


AqvaDry®

� AqvaDry1 is a transparent, UV-curable or thermally curable solution of an active moisture scavenger in an organic matrix.

� Can be used as a film or as a filler.

� It is supplied in syringes sealed under protected atmosphere.

� Deposition can be performed by syringe, blading, spin coating and jet dispensing.


and jet dispensing.

� Deposition must be carried out in dry

nitrogen.

� AqvaDry can be used also with flexible

substrates (Tg = 7 oC).

1This material and its associated products are covered by a PCT patent application deposited by SAES Getters S.p.A.; AqvaDry is a registered trademark by SAES Getters S.p.A.


AqvaDry

OpeningDevice sealing before or after UV curing depending on configuration

Storage at 2-5°C

UV AqvaDry Process Flow


Deposition

AqvaDryuncured film

UV curing Thermal curingAqvaDrycured film

IN GLOVE BOX

on configuration

100mW/cm2 for 15 s λ λ λ λ = 365 nm


AqvaDry

Opening

IN GLOVE BOX

Thermal AqvaDry Process Flow

Storage at 2-5°C


Deposition

AqvaDryuncured film

Thermal curingAqvaDrycured film

Mixing

IN GLOVE BOX

Device sealing possible before curing

70 oC x 20 min


AqvaDry: ODF compatibilityand thermal stability

Uncured AqvaDry film weight loss under different vacuum conditions: perfect compatibility with the ODF process.

Pressure(mbar)

Process Time(h)

wt% loss

1 2 0,1910-2 2 0,1910-3 2 0,19


The uncured material is stable up to 85 °C.

Cured AqvaDry is stable up to 180 °C where a decomposition process starts in the organic matrix.


Thermal expansion coefficient and wettability

Temperature (°°°°C) CTE (1/°°°°C)20 6.9x10-3

60 6.9x10-3

100 4.8x10-2

CTE evaluated by Dynamic Mechanical Thermal Analysis (DMTA).


100 4.8x10-2

Contact angle values measured through the sessile drop method.

Substrate C.A.glass 30.7 ± 1.6stainless steel 51.0 ± 2.1PET 28.7 ± 2.1

glass PET Stainless

steel


Transmittance > 95% for a 100 µm thick filmRefractive index = 1.50

Transmittance spectrum after curing


UV curing / thermal curing


Isothermal scan at 70°C (curing: 30 min)

UV Curing dose: 1.5 J/cm2


AqvaDrysorption performance @ 25 oC / 55% RH



Polymerization

Step polymerization


Polymer begins


• No by-products


APPLICATION

FILLER















Cationic polymerization for adhesive barrier composites

Edge sealant

� Polymerization reaction needs longer time and higher UV dose.� Curing conditions are not suitable for direct OLED stack exposure.


OLED Stack

Edge sealant



� Initiation reaction generally involves Brönsted and Lewis acids.� The inital step needs a high energy dose.


A reactive edge sealant: ZeoGlue®®

A dispensable dryer based on� surface-modified nano-sized LTA zeolite� UV-curable and/or thermally-curable epoxy

formulation

Main properties� no phase segregation due to chemically tailored

particle surface (class-I materials from non-reactive capping agents, class-II hybrid materials


reactive capping agents, class-II hybrid materials from reactive capping agents)

� no leaking pathways within the substrate/scavenger interphase due to particles wetting

� transparency of films in the visible range due to reduced discontinuity of refraction index across the particle/matrix intephase (class-II hybrids)

� excellent adhesive properties due to particles wetting

� good sorption properties (capture rate, capacity, energetics: low H2O vapour pressure)


ZeoGlueparticle size distribution

5,00

10,00

15,00

20,00

25,00

30,00

f(d

) (%

)

XRD LTA POD

0

100

200

300

400

500

600

700

800

900

5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49

2 θ

Inte

nsi

ty


� Mean particle size: 100-300 nm� Very sharp particle size distribution

� inkjettable scavengers� smooth coatings� thin coatings (2-3 µm)� transparent coatings

100 nm

0,00

5,00

0 4 23 133 750 4237

d (nm)

2 θ


ZeoGluedifferent formulations for different deposition techniques

1,0E+03

1,5E+03

2,0E+03

Vis

cosi

ty (

cP)

SPIN COATING

SCREEN PRINTING


Mean particle size and particle size distribution enable getter inks for patterning and local protection

0,0E+00

5,0E+02

5 10 15 20 25

Component A (% wt)

Vis

cosi

ty (

cP)

INK-JET

SPIN COATING

ZeoGlue

C.A. glass 79.7 ± 1.6

C.A. stainless steel 76.5 ± 2.1

C.A. PET 68.7 ± 2.1


Photocalorimetric analysis

UV 365 nm


ZeoGlueWVTR, breakthrough time, lag time


ZeoGluebreakthrough time (85 °C / 85% RH)

reactive edge sealantreactive edge sealantreactive edge sealantreactive edge sealant

glass substrateglass substrateglass substrateglass substrateanodeanodeanodeanode

glass sheetglass sheetglass sheetglass sheet

cathodecathodecathodecathode


dtransversal widthtransversal widthtransversal widthtransversal width


ZeoGluediffusion kinetics


FTIR 3D map of moisture diffusion front (transmittance of OH)


ZeoGluediffusion kinetics

0,80

1,00

1,20

1,40

1,60

Area

ratio

Area

ratio

Area

ratio

Area

ratio

Glue 0h

Glue 24h

Glue 48h

Visible penetration front 24h


Diffusion profiles from border to center of glass-to-glass ZeoGlue aged @ 85 °C / 85% RH. Absorbance ratio OH peak area on epoxy CH3 combination peak to normalize on film thickness.

0,00

0,20

0,40

0,60

0,00 1,00 2,00 3,00 4,00 5,00 6,00 7,00 8,00 9,00

Distance from side to center (mm)Distance from side to center (mm)Distance from side to center (mm)Distance from side to center (mm)

Area

ratio

Area

ratio

Area

ratio

Area

ratio

Visible penetration front 48h


Conclusions

� Even considering the use of the most performing materials today available to seal or protect the displays (glues, barriers, etc.) and the best lay-out, , the introduction of a suitable dryer is mandatory to prevent moisture contamination inside OLEDs.

� Dispensable getter materials properties can be designed by


� Dispensable getter materials properties can be designed by considering the final application requirements

� The integration of novel dispensable SAES getter materials and concepts provide a lifetime insurance for Organic Electronics applications.


Hybrid Polymer Lab.R&D SAES

� Paolo Vacca, PhD

Macromolecular Chemistry, OrganicElectronics

� Dr.ssa Alessandra Colombo

Dispensing, encapsulation, formulations,physico-chemical characterization

� Marco Mudu


� Marco Mudu

Formulations and sampling

� Giorgio Macchi, PhD

Sol gel chemistry, microencapsulation

� Jiabril Gigli, PhD

Rheology, filler/polymer interfacialinteractions, Experimental Design

� Andrea Ravasio, PhD

Polymer waveguides, OrganometallicChemistry


Thanks for your attention


[email protected]

SAES® Getters is a registered trademark of SAES Getters S.p.A.

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