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Towards a flexible OLED display with

an organic active matrix backplane

P. Heremans1, J. Genoe1, S. Steudel1, K. Myny1, S. Smout1,

P. Vicca1, L. Ruppel3, C. Grillberger3, O. R. Hild3, F.Furthner2, B. van der Putten2, A. K. Tripathi2, G. H. Gelinck2

1 2 3 4

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Acknowledgement

FP7 STREP project #216546

start Jan 2008

Flexible Organic Active Matrix OLED displays

forNomadic Applications

FLAMEhttp://www.imec.be/FLAME

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Paul Heremans, SID-ME 2010, Dresden 3

Introduction

Goal: Technology for flexible and rollable OLED display

Implementation: Plastic foil substrate (with moisture barrier)

Organic transistor backplane

Small molecule top-emitting OLED stack

Topstrate barrier foil

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State of the art

48X48 bottom-emitting monochrome OLEDs on flexible substrateT. Jackson: Pentacene TFT driven AM OLED displays, Electron deviceletters 26, 640 (2005)T. Jackson: All-organic active matrix flexible display, Appl. Phys. Lett.

88, 083502 (2006)

12X12 (2mm pixel size), Ta2O5 gate dielectric, aperture ratio 37%M. Mizukami et al.: Flexible AM OLED panel driven by bottom-contactOTFTs, IEEE El. Dev. Lett. 26, 9 (2006)

SONYSID07-1753QQVGAfull color

T. Someya and T. Sekitani: many other backplane appliations!Examples: pressure sensors, image scanner, actuators,

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Outline

Backplane

OLED

Integration

Moisture Barrier

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Pixel

< 1pAIOFF

Requirement

Mobility 0.5 0.03 cm2/Vs

L 5 m

Cox > 20 nF/cm2

VT 0.2 V

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Technology

Laminate foil on carrier Freedom of foil type

Flexibility in process

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Technology

Laminate foil on carrier Freedom of foil type

Flexibility in process

Use of conventional process technology Transferable to flat panel line

CD 2 m

cfr. DowCorning

cfr. Yokogawa

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Technology

Laminate foil on carrier Freedom of foil type

Flexibility in process

Use of conventional process technology Transferable to flat panel line

CD 2 m

Organic thin-film transistors Pentacene (and soluble derivatives) semiconductor (p-type only)

Bottom-gate bottom-contact geometry

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Paul Heremans, SID-ME 2010, Dresden 10

Carrier

glue

PEN Teonex

Planarization

Au (30nm)

resist

Al2O3 (100-150 nm)

Carrier

glue

PEN Teonex

Planarization

Au (30nm)

resist

Al2O3 (100-150 nm)

Drop-on-demand Ink jet

Au (30nm) Au (30nm)

Organic Vapor Phase Deposition

C. Rolin et al., Appl. Phys. Expr. 2, 086503 (2009) C. Kjellanderet al., MRS Fall (2009)

J. Anthony,

JACS123, 9482, (2001)

T. Jackson,

AdvMat15,2009 (2003)

Backplane process

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Performance evaporated pentacene

7

6

5

4

3

2

1

0

um

er

1.00.80.60.40.20.0

[cm2/ Vs]

(AVG) =0.472 cm2/ Vs

(StDev) =0.0174 cm2/ Vs

3.0

2.5

2.0

1.5

1.0

0.5

0.0

Number

-10 -5 0 5 10VT [V]

VT (AVG) = 0.906096 V

VT (StDev) = 0.496683 V

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Inkjet printed TIPS pentacene formulation

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Performance

< 1pA< 1pAIOFF

Requirement Pentacene/Al2O3

Mobility 0.5 0.03 cm2

/Vs 0.5 0.05 cm2

/Vs

L 5 m 5 m

Cox > 20 nF/cm2 50-70 nF/cm2

VT 0.2 V 0.4 V

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Array

Generation 1: 32 x 32

Pixels 1 mm2

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OLED on foil

Top emitting (transparent cathode)

Silver anode

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target

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Transparent cathode

OLED layer stack

interlayer dielectric

Integration of OLED on backplane

Carrier

gluePEN Teonex

Planarization

Au (30nm)

resist

Al2O3 (100-150 nm)

Au (30nm)pentacene

Viahole

Ag anode

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Example green OLED

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Example orange OLED

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Aperture ratio

Top-emitting OLED

Aperture ratio : 79.7%

off

on

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Brightness

D65 white color point

100

80

60

40

20

0

Cox[nF/cm

2]

2 3 4 5 6

0.12 3 4 5 6

12 3 4

Carrier Mobility [cm2/Vs]

2000 Cd/m2

500 Cd/m

2

200 Cd/m2

800 Cd/m2

Al2O3

Polymer gate dielectrics

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Brightness

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Moisture barrier

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5 X 5 mRMS 1.1 nmRmax 10 nm

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Barrier foil

Integration of barrier with OLED on foil

Radius 0.8 cm

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OLED stack

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Summary

Status : Pentacene/Al2O3 backplane with green and orange OLEDs integrated

on foil in 32x32 test vehicles

Moisture barrier with OLEDs integrated on foil and tested forrollability

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Near future : Integrate row and column drivers

Develop top-emitting blue OLED pixels on foil

Apply 3 colors on backplane

Scale pixel size Integrate all in demonstrator

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Thank you

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