© Fraunhofer

S. Amberg-Schwab, U. Weber

Fraunhofer Institute for Silicate Research, Würzburg, Germany

Industrial Production of Encapsulation Materials for Solar Cells

“Development and Upscaling of Nanoscale Transparent Barrier Lacquers

based on Hybrid Polymers”

© Fraunhofer

Outline

1. Aim of flexible high-barrier material development

2. Multilayer approach for barrier materials

3. The POLO® concept

4. Latest results

5. Summary and future prospects

© Fraunhofer

Aim of flexible high-barrier material development

Organic electronic devices: sensitive to oxygen and moisture

Requirements Light-weight, flexibility, transparency Environmental resistancy Low-cost

© Fraunhofer

oxygen permeability

[cm3/m2dbar]

100 100

water vapor permeability

[g/m2d]

10-1 10-1

10-6

10-2

10-6

10-2

packaging films for food

inorganic solar cells

LCDs

OLEDs organic

solar cells

Barrier films for different applications

© Fraunhofer

Barrier properties of laminates and composite materials

Oxygen transmittance (DIN 53 380): 23°C, 50% r.h. Water vapor transmittance (DIN 53 122): 23°C, 85% r.h. to 0% r.h. (PVD: physical vapor deposition)

0,01

0,1

1

10

100

1000

0,01 0,1 1 10 100

BOPP/PE

PET-PEN/PE, laminates with SiOx (PVD)

PET/PE EVOH-laminates

PA/PE

PET/PVDC

PET/PE

WVTR [g/m² d]

aluminum-film-laminates

OTR

[cm

3 /m2 d

bar

]

WVTR [g/m2 d]

© Fraunhofer

barrier properties: 10-5 g/m2 d 10-5 cm3/m2 d bar

Multilayer approach for barrier materials PML®-Process, Vitex USA

Burrows,P.E. et al. MRS Spring Meeting 2002, Boston, USA

© Fraunhofer

Fraunhofer Alliance for Polymer Surfaces POLO®

Bremen IFAM

Potsdam IAP

Dresden FEP

Würzburg ISC

Freising IVV

Stuttgart IGB, IPA

Scale-up of processes IPA, Stuttgart Manufacturing Engin. Autom.

FEP, Dresden Electron Beam and Plasma Techn.

Institutes Know-How

deposition techniques, scale-up

IAP, Potsdam Applied Polymer Research

polymers, surface chemistry, Ca-mirror tests

IFAM, Bremen Manufacturing Technology and Applied Materials Research

adhesive bonding, plasma deposition

IGB, Stuttgart Interfacial Engineering and Biotechnology plasma deposition

ISC, Würzburg Silicate Research

inorganic-organic hybrid polymers (ORMOCER®s)

IVV, Freising Process Engin. and Packaging

Film production, lacquering and lamination, barrier measurements

www.polo.fraunhofer.de

© Fraunhofer

The POLO® concept High-barrier films

1 µm PET film

ORMOCER®

inorganic barrier layer (SiOx)

Inorganic vacuum deposited layers (evaporation, sputtering) in combination with thin barrier coatings based on hybrid polymers (ORMOCER®s) deposited by lacquering techniques Transmission electron micrograph of a thin hybrid polymer coating on SiOx deposited on a flexible PET film

© Fraunhofer

1 µm

inorganic barrier layer (SiOx)

PET film

ORMOCER®

The POLO® concept Ultra-barrier films

Inorganic vacuum deposited layers (evaporation, sputtering) in combination with thin barrier coatings based on hybrid polymers (ORMOCER®s) deposited by lacquering techniques

Inorganic vacuum deposited layers (evaporation, sputtering) in combination with thin barrier coatings based on hybrid polymers (ORMOCER®s) deposited by lacquering techniques Transmission electron micrograph of a thin hybrid polymer coating on SiOx deposited on a flexible PET film

SiOx layer

Source: Langowski, H.C., Fraunhofer IVV: (Ultra-) Barriers for Organic Electronic Applications; Lope-C Convention, Seminar 2009

© Fraunhofer

C. J. Brinker, G. W. Scherer, Sol-Gel Science, The Physics and Chemistry of Sol-Gel Processing, Academic Press, Inc., New York 1990.

solution of precursors

powder sol gel

coatings fibres

bulk

pm nm µm mm

Sol-gel processing: Wet chemistry for hybrid polymers

Main advantages: • low temperature process • high purity materials • transparent molecular composites (nanocomposites)

© Fraunhofer

(CH 2 ) n R’

joining segment

network modifier or

network former

photochemically or thermally induced curing for creating an

Si

RO

RO

RO

hydrolysis and condensation reactions for creating an

network former

inorganic network

sol-gel-process

organic network

Starting compounds Bifunctional silanes

© Fraunhofer

E = Al, Zr, Ti, ...

organic crosslinking

S i O O

O

E

S i O

O O

O O

O S O R

O S i i

Structural units of hybrid polymers

ORMOCER®s Trademark of Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. in Germany

functional groups

hetero-atoms in inorganic structures

inorganic silicate network

© Fraunhofer

Development of new barrier coatings based on hybrid polymers Combined barrier properties 1. Polar permeants (water vapor) 2. Nonpolar permeants (gases, e. g. oxygen, flavors)

© Fraunhofer

Oxygen transmission rates (DIN 53 380) Hybrid polymer (5 µm) on a BOPP-film (30 µm) and on a SiOx-coated film (DIN 53 380; 23 °C, 50 % r.h.)

1600

0

500

1.000

1.500

2.000

BOPP

10

BOPP Hybrid polymer

BOPP SiOx

BOPP SiOx

Hybrid polymer

[cm³/m²*d*bar]

© Fraunhofer

polymer film

SiO x SiO x hybrid polymer

polymer- film

hybrid polymer

Compensation of defects always present in inorganic barrier layers Possible defect healing: vapor-borne + wet coating

© Fraunhofer

SiO x hybrid polymer polymer film

I

I

-Si-O-Si- I

I I

I

-Si O -Si

I

I I

I HO-Si- I

I

-Si-O-Si- I

I

I

I

-Si-OH I

I

-Si-O-Si- I

I I

I

RO-Si- I

I

-Si-OH

layer with increased

network density

Schematic plan of ideal interfacial bonding Covalent bondings at the interface

© Fraunhofer

polymer film

surface roughness polymer film

hybrid polymer

hybrid polymer

Hybrid polymer coating for planarizing the polymer film

© Fraunhofer

Schematic view of the lacquering unit and its clean room environment

Source: Fraunhofer IVV

Fabrication of barrier films Ultra-thin lacquering (IVV) Very thin closed layers need precise protection from dust particles

© Fraunhofer

thickness of hybrid polymer:

~ 20 nm

~ 20 nm

~ 950 nm

Ultra-thin hybrid polymer coatings Transmission electron micrograph

Source: IVV

© Fraunhofer

oxygen permeability

[cm3/m2dbar]

100 100

water vapor permeability

[g/m2d]

10-1 10-1

10-6

10-2

10-6

10-2

packaging films for food

inorganic solar cells

LCDs

OLEDs organic

solar cells

Barrier films for different applications

© Fraunhofer

Transfer of the barrier concept to the market Beside the barrier properties additional properties had to be achieved:

• lacquer components that are nonhazardous to health and environmentally friendly

• UV-stability

• sufficient stability of the lacquers during processing

• long shelf life of the lacquers, preferably without cooling

• R2R-processability under production conditions with reproducible and stable coating qualities

• stability in the damp-heat-test (85 °C / 85 % r. h.: 2000 hours)

© Fraunhofer

Break-through: Industrial production of low-cost encapsulation materials for inorganic solar cells at ISOVOLTAIC AG in Austria

Quelle: IVV

© Fraunhofer

oxygen permeability

[cm3/m2dbar]

100 100

water vapor permeability

[g/m2d]

10-1 10-1

10-6

10-2

10-6

10-2

packaging films for food

inorganic solar cells

LCDs

OLEDs organic

solar cells

Barrier films for different applications

© Fraunhofer

Pilot R2R production of barrier films Sandwich structure

Calculated for ambient conditions

(23 °C, 85 % rh; factor 2,8) 7x10-5 (g/m2 d)

© Fraunhofer POLO

Pilot R2R production of barrier films Sandwich structure

lamination adhesive

6 / 17

barrier film-2

barrier film-1

• mechanically robust process • higher mechanical stability • however, thicker structures

Pilot R2R production of barrier films Face-to-face adhesive lamination of barrier films

© Fraunhofer

active barrier

oxygen scavenger layer

barrier layer based on hybrid polymers

inorganic barrier layer

Future prospects: Combination of passive and active barriers

passive barrier

O2 O2 O2

© Fraunhofer

The POLO® concept for high- and ultra-barrier films

Hybrid polymers as barrier lacquers

Thank you very much for your kind attention

Promising barrier results and future prospects

Industrial production of low-cost encapsulation materials for inorganic solar cells