11 Leo Novaled TU Dresden

8/12/2019 11 Leo Novaled TU Dresden

1/23

Organic Light Emitting Diodes:Display and Lighting Technology of the Future

Karl Leo

Institut fr Angewandte Photophysik, TU Dresden, andFraunhofer-Institute fr Photonische Mikrosysteme, Dresden


2/23

Motivation:What is possible with OLED:Samsung 40 TV display


3/23

Organic Semiconductors

Photovoltaic cellsOrganic materials Integrated circuits

Large area & flexible substrates possible

Large variety of materials

Low cost


4/23


5/23

pzpz

sp2 sp2

plane of thesp 2-orbitals

p z-orbital -bond

-bond

-bond

p z-orbital

The basics of organic semiconductors:Conjugated -electron systems

Sp2-hybridised Carbon:


6/23

delokalisierte

Elektronen

pz

sp2

6 x

18 x

LUMO (*) => ECconduction band

HOMO () => EVvalence band

-electron systems delocalize!

VdW crystals small -overlap, narrow bands saturated electron system

delocalized

-electrons

Molecules with conjugated -electron system

Technology: vapor deposition


7/23

Device energy diagram

E

x

Cathode

LUMO

HOMO

Anode

Device structure

V

A

Light emission

Organic Light Emitting Diodes

OLEDs: Basic Principles

Glass substrate

Transparent anode

Emissive layer

Cathode

+

+ +

--

-

300nm


8/23

Organics Collaboration Dresden

Institut frAngewandte Photophysik

IAPP, University of Dresden (www.iapp.de, approx. 40 people)

Basic research on novel device concepts

Low-voltage OLED

Fraunhofer-IPMS Dresden (www.ipms.fraunhofer.de, approx. 25 people)

Process development with highly efficient OLEDs

OLED-Inline-deposition set-up (30x40cm Substrate)

Driving Electronic for OLED-Displays

Small to medium volume fabrication

Novaled GmbH (www.novaled.com, approx. 45 people)

Highly efficient OLED-stacks for RGB-Displays

Technology licensing


9/23

Exponential current-voltage relation

Flat-band under operation

Low work-function contacts not needed !

p n

Why doped transport layers:

Inorganic vs. Organic LED

Inorganic LED (e.g., GaAs/AlGaAs) Organic LED

CB

VB

EFe

EFh

Metal

space charge limited currents

low work function metals neededITO-preparation necessary

HTL

ETL


10/23

Double emission layer (D-EML) structure

D-EML structure

Al

BPhen:Cs

BPhen

TAZ:Ir(ppy)3

TCTA:Ir(ppy)3

Spiro-TAD

MeO-TPD:F4-TCNQ

ITO substrate

n-doped ETL

HBL

PET-EML

PHT-EML

EBL

p-doped HTL

p-HTL

EBL

HBL

EML2

ITO

Al

n-ETL

EML1

Self-balancing EML system no charge accumulation at interfaces

X. Zhou et al., Appl. Phys. Lett. 81, 4070 (2002)


11/23

2.6 2.8 3.0 3.210

100

1,000

10,000

Luminance(cd/m2)

Voltage (V)

1,000 cd/m2@ 2.9V

61.5 cd/A; 67 lm/W

100 cd/m2@ 2.68V

64 cd/A; 75 lm/W

Highly efficient & stable PIN Triplet OLED:

World record in efficiency

G. He et al., Appl. Phys. Lett. 85, 3911 (2004)

Highly efficient devices are also most stable devices

Efficiency higher than for best green nitride LED


12/23

Lifetime of PIN-OLEDs

OLEDAsia Seoul 2005

Current status:phosphorescent red (0.68, 0.32):

100,000 h at 500 cd/m

phosphorescent green (0.38, 0.59): 25,000

h at 500 cd/m (Irppy3 based)

fluorescent blue (0.15, 0.17):6,000 h at 500 cd/m

Novaled pin-OLEDs have reached state of

the art lifetimes for emitter systems in all

three colors samples still contain Cs as n-dopant

100 1.000 10.000

1.000

10.000

100.000

1.000.000

Lifetime/

h

Luminance / cd/m2

200,000 h @ 150 cd/m2

30,000 h @ 500 cd/m2

8,000 h @ 1000 cd/m2

n = 1.7

Red triplet pin OLED


13/23

OLEDFAB Project

OLEDFAB Projekt iniated by Thomson und BMWA/SMWA

Novaled leads Saxonian consortium with IPMS und IAPP

Goals:

- Demo of a 5 inch active-matrive display with highly efficient pin technology

- Display manufactured using novel inline technology

Other partners:

- Applied Films- Labor fr Bildschirmtechnik Stuttgart

- Deutsche Thomson Brandt


14/23

Full color AM display based on pin technology

Performance:

operating voltage for 100cd/m2:

around 7V (OLED + backplane)

power consumption:

240mW@100cd/m2 (in forward

direction only, video mode) about 60% of equivalent LCDdisplay

Active matrix OLED made in joint project by ITRI (Taiwan), Thomson (France) and Novaled

Panel emitting in both directions on n-channel LTPS backplane (3.25, QVGA, 130dpi)based on PIN structure

OLEDFAB: Display with improved backplane

in preparation


15/23

Even higher Light Efficiencies: out-coupling enhancement

OLEDAsia Seoul 2005

Efficiency at 1000 cd/m: 110 lm/W (with outcoupling enhancement)

Novaled focuses on furtherimprovement of their recordbreaking efficiencies byout-coupling enhancements(target 2005: 140lm/W)

10 100 1000 100000

20

40

60

80

100

120

Powerefficiency(lm

/W)

Luminance (cd/m)

Green phosphorescent PIN OLED

with outcoupling enhancement


16/23

Institut fr Angewandte Photophysik

Technische Universitt Dresden

LED performance vs. time

1965 1970 1975 1980 1985 1990 1995 2000 2005

0

20

40

60

80

100

120

0

20

40

60

80

100

120

OLED white Red Filtered

Tungsten Bulb

(unfiltered)

Fluorescent Lamp

InGaN

green

OLED

PLED

AlInGaP Red/Yellow

PowerEfficie

ncy(Lumen/Wa

tt)

Year

Dresden leading

in both RGB and

white


17/23

OLED Lighting Applications

source: Philips Lighting March

2004 GE demonstrator

Signage General lighting


18/23

Technology Roadmap (USDC)

(Diffuse lighting)


19/23

OLLA project

OLLA EU 6th Framework Integrated Project initiated by Philips

OLLA: Organic LED for Lighting Applications

Aims:

- Highly Efficient white OLED

- Large Area OLED- Low-Cost manufacturing

Other German partners:

- Siemens-Osram, Aixtron, Covion, HCStarck, Syntec, Novaled

- FhG-IPMS, TU Dresden, Uni Kassel

about 15 further partners from other European Universities


20/23

Achieve Smooth Transition from R&D to production: Close Collaboration of

Fraunhofer Society and Industry

Topics: OLED for Displays and Lighting

Organic Solar Cells

Memory and other Applications

Tools:

- Gen 2 Inline Pilot Production Tool (Displays&Lighting)- Reel-to-Reel R&D tool

Location: New IPMS cleanroom: Virtually no building investment

A new Initiative: Center for Organic Materials and

Electronic Devices Dresden (COMEDD)


21/23

Outline of COMEDD

Investment by FhG/state of

saxony

Operations organized in

projects

Projects are defined by

advisory committee

OLED foundry does pilot

manufacturing

Projects Tools

Inline Reel-to-Reel

Manufacturing Manufacturing

Center for Organic Materials and

Electronic Devices Dresden (COMEDD)

Advisory Board

Funding agencies,

FhG, Industry

COMEDD

Operations

Funding

agencies:

Saxony

BMBF, EC

OLED

Foundry


22/23

OLED have still a long way to go, but

Lifetime problem is close to being solved even for demanding

applications

Efficiency:

OLED displays: will beat all other FPDs

OLED lighting: should be able to surpass fluorescent tube

COMEDD: New initiative to establish OLED manufacturing in

Saxony

Conclusions


23/23

Acknowledgment

M. Pfeiffer, J. Blochwitz-Nimoth, G. He, G. Schwartz, K. Fehse, K.

Walzer X. Zhou, J. Huang, A. Werner, A. Nollau, J. Drechsel, B.Mnnig, K. Harada, T. Fritz, B. Plnnigs, A. Beyer

J. Amelung, W. Jeroch, C. May, M. Schreil, M. Toerker, U. Todt (FhG-

IPMS)

D. Alloway, P.A. Lee, N. Armstrong, Tucson (XPS/UPS)

N. Karl (Stuttgart)

D. Whrle (Bremen), J. Salbeck (Kassel), H. Hartmann (Merseburg) C.J. Bloom, M. K. Elliott (CSU)

BMBF, SMWA, SMWK, DFG, EC, FCI, NEDO

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11 Leo Novaled TU Dresden

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