Changhee Lee School of Electrical Engineering and Computer ... · PDF fileChanghee Lee, SNU,...

Changhee Lee, SNU, Korea

디스플레이공학 I2005. 1학기 OLED

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Changhee LeeSchool of Electrical Engineering and Computer Science

Seoul National Univ. [email protected]

Changhee Lee, SNU, Korea


1

Outline• Introduction to OLED displays- History of OLED display - OLED materials- OLED fabrication and color patterning- Characteristics of OLED displays and comparison with other technologies- OLED applications

• Basic physics and chemistry of organic semiconductors- Carbon, Chemical bonds, Electronic energy structure- Optical properties of organic semiconductors- Electrical properties of organic semiconductors

• OLED device physics- Carrier injection and transport- Electron - hole recombination and emission of light- Doping: fluorescent or phosohorescent dopants- Electroluminescence efficiency- OLED reliability and degradation

Changhee Lee, SNU, Korea2

디스플레이공학 I2005. 1학기 OLEDAdvantages of OLEDs

• Superior viewing performance:emissive bright colors, wide viewing angle, fast response time, and high contrast

• Excellent operating characteristics:low operating voltage, power efficient, and wide temperature range

• Good form factor:Thin, light-weight, rugged, and flexible

• Simple fabrication processes: vacuum deposition, inkjet printing, spin coating,roll-to-roll (web) processing

Vacuum Deposition

Fine Metal Shadow Mask

Substrate

Source

Ultimate Portable Communication Devices

http://www.universaldisplay.com/

Red

Ink-jetGreen

Inkjet Printing

Blue



Small Molecule OLED

’87 ’88 ’89 ’90 ’91 ’92 ’93 ’94 ’95 ’96 ’97 ’98 ’99 ’00 ’01 ’02

1st Polymer LEDCambridge

ITO/PPV/Al

KodakBilayer

ITO/Diamine/Alq3/Mg:Ag

PioneerQuinacridone

doping

UCSBCasting withMEH-PPV

PioneerAlLi cathode

UniaxFlexible PLED

PET/ PANI/ MEH-PPV/Ca

Linkoping U.Variable Colors from

Polymer Blend

Idemitsu Kosan CCM

TDK Poly-Si TFT

Yamagata U.White OELD

UCSB, Cambridge, UtahLasing from

Polymer Microcavitiy

Princeton U.SOLED

Seiko-EpsonInk-Jetprinting

Pioneer Full-color PMOLED

By shadow mask

Kodak LiF/Al cathode

Princeton U.Phosphorescent

OLED

SonyTop-emission

13.1” AMOLED

Polymeric OLED

’03 ’04

SDI3.6” LITIAMOLED

Seiko-Epson40” full color PLED

Ink-Jet

TMD17” full color PLED

Ink-Jet

Sanyo-KodakLTPS-TFT AMOELD

IDTech20” AMOLED

α-Si TFT

Seiko-EpsonInk-Jet

full color

SDIBoth-side emissive

2.2” AMOLEDLGE-LPL

20.1” AMOLEDLTPS-TFT

’05

SEC21” AMOLED

α-Si TFT

SDI17” AMOLED

Non-laser LTPS-TFT

KodakFluorescentdye doping

1st OLED1982

C. W. TangUSP

4,356,429

1983R. H. Partridge

PVKPVK/SbCl5 doping

1960sOrganic Single

crystals

1980sorganic

Thin films

SonyAMOLED3.8” PDA

Dr. Ching W. TangEastman Kodak

Sir Richard Friend, FRSUniversity of Cambridge

CambridgeChemical Tuning

of PolymerIBM, Bayer

PEDOT:PSS

OLED History


디스플레이공학 I2005. 1학기 OLEDC. W. Tang (Kodak): 1st OLED

C. W. Tang and S. A. VanSlyke, Appl. Phys. Lett. 51, 913 (1987)

ITO

Diamine

Alq3

Mg:Ag

Glass

+ ++

-ΦeLight

Φmetal

HOMOAlq3

LUMOAlq3

HOMODiamine

LUMODiamine

ΦITO

Electron

hole

60

40

20

0Li

ght (

arb.

uni

ts)800700600500400

Wavelength (nm)

Alq3

NO

NON

O Al

- -

• High efficiency: 1 % quantum efficiency (electron/photon), 1.5 lm/W luminous efficiency• Low drving voltage: more than 1000 cd/m2 below 10 V



PPV

CH

PPV precursor

Cl-

SCH2ClClH2C

+SCl-

S+Cl-

CH2

S+n

n

250oC

Vacuum

MeOH, 50 oC

-OHH+

Dialysis

Synthetic route of PPV

Glass Substrate

ITO

PPV

Al

1.0

0.8

0.6

0.4

0.2

0.0El

ectro

lum

ines

cenc

e (a

rb. u

nit)

2.42.22.01.8

Energy (eV)

120 K

147 K

200 K

235 K

285 K

Cambridge Group: 1st Polymer LED

J. H. Burroughes, D. D. C. Bradley, A. R. Brown, R. N. Marks, K. Mackay, R. H. Friend, P. L. Burns, and A. B. Holmes, Nature 347, 539 (1990).



0.20

0.15

0.10

0.05

0.00

EL (a

rb. u

nits

)

800700600500

Wavelength (nm)

N N

N NPt

PtOEP

Princeton/USC Group: Phosphorescent OLED

M. A. Baldo, et al, Nature 395, 151 (1998)

Efficient red EL emission from triplet excitons: ηext ~ 2.2% @ 100 cd/m2



Key OLED Patents

• Small Molecule (SMOLED)

C. W. Tang, US Patent 4,356,429 (1982) – Organic electroluminescent cell

S. A. VanSlyke, C. W. Tang, US Patent 4,539,507 (1985) – Organic electroluminescent devices having improved power conversion efficiencies

• Polymer (PLED)

Friend, et al., US Patent 5,247,190 (1993), WO 90/13148 – Electroluminescent devices

Holmes, et al., US patent 5,401,827 (1995), WO 92/03490 – Semiconductive copolymers for use in luminescent devices

• Phosphorescent Molecule (PhOLED)

Thompson, et al., WO 00/70655 – Very high efficiency organic light emitting devices based on electrophosphorescence

Forrest, et al., US Patent 6,515,298 (2003), WO 01/08230 – Intersystem crossing agent for efficient utilization of excitons in organic light emitting devices



Updated the data in J. R. Sheats et al., Science 273, 884 (1996).

Blue

White

Red

Green

PDP

AMLCD

CRT

Conventional LEDs

1960 1965 1970 1975 1980 1985 1990 1995 2000 20050.1

1

10

100

Green Yellow

Green 110 lm/W

White OLED20 lm/W

Polyfluorenes

PhosphorescentOLED

Polymers

Molecular Solids

Nitrides

BlueSiC

Organic LEDs

PPV

BlueInGaN

GreenInGaN

Thomas Edison'sfirst bulb

Unfiltered incandescent lamp

Fluorescent

Alq3

Orange-RedAlInGaP/GaP

- OrangeRedAlInGaP/GaAs

RedAlGaAsP/AlGaAs

RedAlGaAsP/GaAs

YellowRedGaAsP:N

GreenGaP:N

Red

GaP:Zn,O Red

GaAs0.6P0.4

Year

Evolution of OLED PerformanceLu

min

ous

Effic

ienc

y (lm

/W)



Dendrimers

Overview of OLED Materials

OLED Emitting Materials

Small Molecules

• Quinolates(Kodak)

• DPVBi based (Idemitsu-Kosan)

• Spiro compounds (Covion)

• Phosphorescent (UDC, Opsys)

• PPVs(Philips, CDT, Covion)

• Polyfluorenes(Dow, CDT)

• Spiro bifluorenes(Covion)

Polymers Oligomers Dendrimers

• ADS

• Elam-T

• Opsys

Ref. SRI report


디스플레이공학 I2005. 1학기 OLEDHost and Fluorescent Dopant Materials

N

O

N C C N

N

2

DPVBi

Idemitsu Kosan

Alq3Red shift

modifiedGaq3

Perylene

distyrylbiphenylIdemitsu Kosan

Pioneerquinacridone

DPTDPT

rubrenerubrene BTXBTX

ABTX

DCJTBKodak

Kodak

Kodak

B G Y Or R

Host

Dopant

SN

O

OHS

O

OCH3

NH

HN

O

O

NO

NON

O Al

Mitsubishi

Mitsubishi Mitsubishi

Mitsubishi

TDKL

(R)m

2

(R)m

NO

NON

O Al

C H3

H3CC H3

NO

NON

OGa

m-Alq3

Alq-family

Prof. S. K. Kwon (K.N.U.)



RedGreen

Dopant

Hole/ExcitonBlockingMaterials

Host

Blue

BCP C60F42

CN-PPV

CBP

mCP

UGH2 TAZ

PVK

FIrpic(CF3ppy)2Ir(pic)

Ir(ppy)3

Ir(ppy)2acac

Ir(mpp)3PtOEP

Btp2Ir(acac)NIr

O

2

ON

F

F

IrN

O O

2

NIr

N

O O

CF3F3C

2

n

O

CN

CHCH2 nN

N N

NNH3C CH3

NN

N

N N

N N

N NPt

NIr

O

2

O

S

FF

F

F

FF F

FFF F

FFF F

F F

FF

F

F

F

F

F FF

FF

F

F

FF

F

F

F

F

FF

FF

FF

NIr

3

Si CH3H3C

NIr

2

H3C

Host and Phosphorescent Dopant Materials

Dr. H. N. Cho (InkTek)

NO

N

O AlO

BAlq



BCP, Balq, etc.-Exciton blocking layer

> 1000 Å50 ~ 100 ÅExciton diffusion length

100 %25 %Maximum quantum efficiency

< 10,000 hour10,000 ~ 20,000 hourLifetime

Red: 6~20 cd/AGreen: 17~38 cd/ABlue: ~ 10 cd/A

Red: ~6 cd/AGreen: ~20 cd/ABlue: ~6 cd/A

Luminous efficacy

5 – 15 %0.1 ~ 3 %Dopant concentration

TripletSingletExcited state

CBP, mCPAlq3, ...Host

PhosphorescenceFluorescence

Comparison of fluorescent and phosphorescent OLEDs


디스플레이공학 I2005. 1학기 OLEDHole Transporting and Electron Transporting Materials

NN

N

N

NN

CH3

H3C

CH3

NN

O(H3C)3C

NO

NO N

OAl

Hole-transporting materials

Electron-transporting materials

GlassITOHIL

HTL

ETL

Cathode

EML

＋

－

N N

CH3

H3C

TPD

α-NPD m-MTDATA

NN

N

TAZ

Alq3PBD


디스플레이공학 I2005. 1학기 OLEDHole Injection Materials

GlassITOHIL

HTL

ETL

Cathode

EML

＋

－

CuPCCopper Phthalocyanine

PEDOT(Poly(3,4-ethylenedioxythiophene)

Cu

N

N

N

N

n

SO3- SO3

-SO3H SO3H SO3H SO3H

SS

SS

SS

O O

OO

O O

OO OO

n

Andreas Elschner (H.C.Starck), Micro Symposium 2002 (Cologne, 2002. 12. 9)


디스플레이공학 I2005. 1학기 OLEDLight Emitting PolymersLight Emitting Polymers

Polyfluorene-based EMLs PPV-based EMLsR1

R2nn

R1 R2

Ar'

Blue to Green or Red Green to redish Orange




Phosphorescent Polymers

Blend Type

Main Chain Type

Side Chain Type



디스플레이공학 I2005. 1학기 OLEDCurrent status of OLED efficiency and lifetime

SID200425,000 @ 600 nit0.31, 0.6427Green

SID2004-0.39, 0.3938White

White

Blue

Light blue

Green

Red

Light blue

Orange

Red

SID2004-0.14, 0.238

SID200423,0000.30, 0.3412

Organic Electronics 4, 155 (2003)

>15,000 @ 300 nit0.65, 0.3512

PLSID200415,000 @ 300 nit0.61, 0.3822

SID20047,0000.15, 0.155.9

SID200421,0000.17, 0.3012

SID200440,0000.32, 0.6219

EL2004>80,0000.65, 0.355.5

FL

ReferenceHalf-Life (hr)

@ 1000 cd/m2CIE (x,y)

Efficiency (cd/A)

Color

* Fluorescent data : C. Hosokawa, K. Fukuoka, H. Kawamura, T. Sakai, M. Kubota, M. Funahashi, F. Moriwaki and H. Ikeda (Idemitsu Kosan), SID 04 Digest, 780 (2004) Paper 17.1

* Phosphorescent data: Yeh-Jiun Tung, Tan Ngo, Michael Hack, and Julie Brown, Naotaka Koide, Yoshiaki Nagara, Yoshifumi Kato, Hironori Ito, SID 04 Digest, 48 (2004), paper 5.2



Methods of Full Color Display Fabrication

RGB method Color conversion method Color filter method

Glass

Anode

HTL

Blue emitting layerETL

Cathode

Red Green Blue

CathodeETL

Anode

Glass

Red Green Blue

Color conversion filter

HTL

White emitting layer

CathodeETL

Anode

Glass

Color filter

Red Green Blue


디스플레이공학 I2005. 1학기 OLEDFabrication Methods of OLEDs: small molecules

Vacuum Deposition

Fine Metal Shadow Mask

Substrate

Source



Small AreaLow material Usage

Large AreaHigh Material Usage

Point Source Linear Source

Evaporation sources



ITO Stripes

Glass Substrate

CathodeSeparator

Cathode Stripes

Organic layer


디스플레이공학 I2005. 1학기 OLEDFabrication Methods of OLEDs: small molecules

OVPD

Cooled Carriersubstrate

Organic sources

Heater Showerhead

Evaporation cells

N2 N2



Spin Coating

ITO substrate

Solvent Saturated Atmosphere

Spinner Cover

Spinner Motion

Spun Film

Spinner BaseSpinner Bowl

Fabrication Methods of OLEDs: Polymers



Process Description (Polymer LED)

Glass with ITO

Structure ITO

Apply Metal-pad

Apply PANI or PEDOT

Structure Polymer & PANI

Apply Polymer

Apply Cathode

Encapsulate

Photolithography

Sputter/Photolith.

Spin Coat

Spin Coat

Laser Ablation

Vacuum Depositon

Adhesive + Lid



Ink-jetcartridge

Glass

Transparent electrode: ITO

Polyimide bank

Conducting polymer (PEDOT/PSS)

Red ink

Green ink

Cathode (Al/Ca)

Blue ink

Fabrication Methods of OLEDs: Polymers



Fabrication Methods of OLEDs: Molecules, Polymers

glass

Color donor sheetsLaser

LITI Process (small molecules, polymers)Samsung SDI / 3M

Samsung SDI, 17” UXGA (1,600×1,200) AMOLED



유리기판

양극

정공수송층 (HTL)발광층 (EML)전자수송층 (ETL)

음극

PMOLED 구조

정공수송층 (HIL)

PMOLED



Bottom Emission Top Emission

AMOLED

Al WiringLight

Metal Cathode Transparent Anode

Metal Anode

Translucent Cathode

Transparent Plate

Light

Emissive Layer

Buffer Layer

Emissive Layer

IC

FPC

TFTOLED pixel

TFT backplane

Driver IC

Light Emission

GlassITOHILHTL

ETLCathode

EML

＋

－



AMOLED TFT-LCD

Backlight

LiquidCrystal

ColorFilter

IC

FPC

IC

FPC

TFTOLED

TFT backplane

Driver IC

Response TimeViewing angleLCD OLED

Display Characteristics: OLED vs LCD

Kodak website



Cell Phone Power Consumption Comparison

2” IMT-2000 Cell phone, R:G:B = 3:6:1, 50% polarizer efficiency, 30 % of pixels lit

AMLCDs

Fluorescent AMOLEDs

Polymer AMOLEDs

Phosphorescent AMOLEDs

Luminance (cd/m2)

Pow

er C

onsu

mpt

ion

(mW

)

0 20 40 60 80 100

50

100

200 4 ~ 6 mm

LCD

Backlight

LCD

3 ~ 4 mm

LCD

Backlight

OLED

2.5 ~ 2.8 mm

OLED OLED



Comparison of CRT, PDP, LCD, and OLED - TV

Lifetime

Weight/Thickness

Power consumption

Color Fidelity

Image Sticking

Response time

Viewing Angle

Dark condition

Bright conditionContrast

Peak White

Full BlackLuminance

High Resolution

Large Size

OLEDLCDPDPCRTClassification

Excellent Good Fair Need to be improved Dr. C. W. Tang, ICEL-5



Segment(area color)

Lighting

Active matrix

Passive matrix

TVHDTV

Notebook PCPC Monitor

DVD PlayerPDADigital Camera

Cell phone, MP3 playerCar stereo

AlphanumericDisplays

LCD backlightGeneral lighting

Dot Matrix

OLED Displays: Applications



OLED Displays: Applications

• Monochrome applications* Small monochrome displays for hand-held electronic devices (cell phones, etc.). * Niche applications such as head-mounted displays.

• Multicolor applications* Small displays for hand-held electronic devices (cell phones, PDAs, digital cameras, GPS, etc.). * Car electronics (radios, GPS displays, maps, warning lights, etc.)* Instrument electronics, heads-up instrumentation for aircraft and automobiles.

• Full color application* LCD backlights (white light) * Small full color displays. * Full color, high-resolution, personal communicators* Large displays: TV, monitors* Ultra-lightweight, wall-size television monitors



iSuppli, 2004. 9

Worldwide OLED Display Value by Application



Samsung LG Electronics

Sanyo-Kodak 2.2” Full-color AMOLED

Sony ‘CLIE’ PDA 3.8” Full-color

AMOLED

PhilipsPioneer

PMOLED

AMOLED

Neosol (Korea) ‘CLIOD’ TMR(TV+portable multimedia player)

2.2” Full-color AMOLED

OLED Products



Seiko-Epson40” WXGA (1280x768) tiledAMOLED (Ink-jet printing)

LG Electronics-LG Philips LCD20.1” XGA (1280×800) Poly-Si TFT AMOLED

Samsung Electronics21” WXGA(1280x768) α-Si TFT AMOLED

Samsung SDI17” UXGA (1,600×1,200) Poly-Si TFT AMOLED

Large Area AMOLED



$0

$500

$1,000

$1,500

$2,000

$2,500

$3,000

$3,500

2002 2003 2004 2005 2006 2007 2008 2009 2010

AMOLEDPMOLED

Year

Mill

ion D

ola

rs

Ref. iSuppli 2004. 9

OLED Displays: market

Pioneer

35.9%

RiTdisplay15.5%

Philips2.9%

Others4.6%

SamsungSDI

41.1%

Market share (2004)



Mobile Phone• 2” QVGA• 1.8” QCIF

Digital Still Camera• 2” Delta

PDA• 3” ~ 4” HVGA or VGA

Entertainment• 4” ~ 6” VGA or WVGA

Car Navigation• 7” VGA or WGA

Notebook• 12” ~ 14”

Desktop PC• 15” ~ 20” SXGA

TV, HDTV• 15” ~ 40” SVGA or WSVGA

Mannfacturing• 2G or 3G manufacturing line

Technology• LTPS-TFT AMOLED• Small Molecule

Mannfacturing• 3G manufacturing line

Technology• LTPS-TFT AMOLED• Small Molecule• Thin film encapsulation

Mannfacturing• 4G ~ 5G manufacturing line

Technology• Super Grain Si-TFT AMOLED• a-Si TFT AMOLED• Small Molecule, Polymer

2004 2005 2006 2007 2008 2009

DisplaySize &

Application

TechnologyRoadmap

OLED Displays: Roadmap



OLED Roadmap20032001 2005 2007 2009 2011

1

Gen 1300x400

18”10.4”(x2)

1999

1.45

Gen 2370x470

20”10.4”(x4)

Gen 4730x920

40”17”(x6)

3

Gen 3550x650

26”12.1”(x6)

5.6

Gen 51000x1200

46”17”

(x12)

10

GenGlass

Max panelMain

Product

Lifetime (hour)Lum. Eff. (lm/W)

Drive MethodTFT

EncapEmitterProduct

5,0005

PMLTPS

Metal canSmall Mol.Cell Phone

20,00010

AM TopLTPS/a-Si

Glass, Hybrid S/M, Polymer

Monitor, TV

40,00020

AM TopNon-laser/a-Si

Glass, FilmPolymerHDTV

10,0007

AM BottomLTPS

Glass canSmal Mol.

PDA

Pioneer

Kodak 5.5”Sony 13” IDTech 20” Samsung SDI 17”

KodakLG



UDCPioneerDNP

Covion

Flexible OLED Displays

Future DisplayFuture Display


디스플레이공학 I2005. 1학기 OLEDFlexible Display: Roll-to-roll coating

Bell Labs/DuPont/Sarnoff

Ref. MRS Fall 2002, Dupont

Roll-up computer

J. M. Shaw, P. F. Seidler, IBM J. Res. & Dev., 45, 3 (2001)

Philips

Changhee Lee School of Electrical Engineering and Computer ... · PDF fileChanghee Lee, SNU,...

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