OLED Display Technology

Overview of OLED Display Technology

Homer Antoniadis, Ph.D. Product Development Group Manager phone: (408) 456-4004 cell: (408) 314-6460 email: [email protected]

Homer Antoniadis | OLED Product Development| page:1 Outline

! OLED device structure and operation ! OLED materials (polymers and small molecules) ! Evolution of OLED performance ! OLED process and fabrication technologies ! Color capabilities ! White emitting OLEDs ! Passive and active matrix driving schemes ! OLED market potential ! Products and demonstrators

Homer Antoniadis | OLED Product Development| page:2 OLED Display and Pixel Structure

Display Pixel

Cover glass

Cathode Emissive polymer layer Cathode (Ba,Ca/Al 2000 Å)

Emissive polymer layer ~ 800 Å

Conducting Conducting polymer layer polymer layer ~ 1200 Å

Epoxy Anode (ITO 1500 Å)

Anode Single pixel structure

Glass substrate

Human hair is 200X the thickness of the OLED layers

Homer Antoniadis | OLED Product Development| page:3 OLED Device Operation Principles

OLEDs rely on organic materials (polymers or small molecules) that give off light when tweaked with an electrical current Ca_tho_de _ _ _ _ _ ! Electrons injected from cathode Emissive polymer _ ! Holes injected from anode _+ _+ _ ! Transport and radiative recombination of electron hole + + + V Conducting polymer pairs at the emissive polymer + + + + Anode + + + + + OLED device operation (energy diagram)

Conducting Emissive polymer Cathode- polymer Transparent Anode layer (s) substrate light (ITO) - - LUMO e e LUMO

Light HOMO HOMO h+ h+ h+ ca. 100 nm 10 - >100 nm <100 nm >100 nm

Homer Antoniadis | OLED Product Development| page:4 Optoelectronic Device Characteristics

Luminance-Current-Voltage Efficiency-Luminance-Voltage 100 12 12

10-1 )

2 10 10 10-2 8 10-3 8 6 10-4 6 10-5 4 Efficiency (cd/A) -6 4 Efficiency (cd/A) Current Density (A/cm 10 2 10-7 2 0 10 100 1000 10000 -8 -6 -4 -2 0 2 4 6 8 2 02468 Voltage (Volts) Luminance (cd/m ) Voltage (V) 105

4 LUMINANCE is the luminous intensity per unit 10 area projected in a given direction ) 2 103 The SI unit is the candela per square meter 102 (cd/m2), which is still sometimes called a nit

101 The footlambert (fL) is also in common use: Luminance (cd/m 2 100 1 fL = 3.426 cd/m

10-1 02468 http://www.resuba.com/wa3dsp/light/lumin.html Voltage (Volts)

Homer Antoniadis | OLED Product Development| page:5 Evolution of LED Performance

SM OLED

Polymer OLED

Courtesy of Agilent Technologies

Homer Antoniadis | OLED Product Development| page:6 Electroluminescent Polymers

Conducting polymers ! Polyaniline (PANI:PSS) NH ! Polyethylenedioxythiophene (PDOT:PSS) PANI PDOT PSS Emissive polymers

! Polyphenylenevinylene R1 (R-PPV) ! Polyfluorene (PF) n R1 n R1 R1 R-PPV Processed by : PF Spin casting, Printing, Roll-to-roll web coating

IP owned by Cambridge Display Technology

Homer Antoniadis | OLED Product Development| page:7 Multiple emission colors achieved by Covion

Different emission colors can be obtained with a variety of chemical structures

300 nm 500 nm 700 nm PPP

PPV

OR CN PT or S CN-PPV RO

Homer Antoniadis | OLED Product Development| page:8 Multiple emission colors achieved by Dow Chemical

n R1 R1 PF

Homer Antoniadis | OLED Product Development| page:9 Polymer OLED display fabrication steps

Deposit and pattern anode (ITO)

Pattern polymer layers (first conducting then emissive) Spin coating Ink Jet printing Screen printing Web coating

Vacuum deposit and pattern cathode (Ba,Ca/Al)

Homer Antoniadis | OLED Product Development| page:10 Ink Jet Printing to Pattern Polymers (Full Color Applications)

Ink Jet Head

Red Green Blue emitter emitter emitter

Substrate

Ink Jet printing to define and pattern R, G, B emitting subpixels

Homer Antoniadis | OLED Product Development| page:11 The Holy Grail: Flexible OLEDs

Sheila Kennedy, Harvard Univ., 1999

Homer Antoniadis | OLED Product Development| page:12 Electroluminescent Small Molecules

Hole transport small molecules

! Metal-phthalocyanines NN ! Arylamines, starburst amines NPD

Emissive small molecules ! Metal chelates, distyrylbenzenes N O ! Fluorescent dyes O N Al O N

Processed and deposited by : thermal evaporation in vacuum Alq3

IP owned by Eastman Kodak

Homer Antoniadis | OLED Product Development| page:13 Polymer and Small Molecule Device Structures

Small molecule Polymer

Cathode -LiF/Al Cathode –Ba, Ca/Al

ETL -Alq3 ETL - PPV, PF

EML - doped Alq3

HTL -NPB HIL - PDOT, Pani HIL -CuPc Anode -ITO Anode -ITO Substrate -glass Substrate - glass

Multi-layer structure Bilayer structure made all in vacuum made from solution

Homer Antoniadis | OLED Product Development| page:14 Full color patterning with small molecules

substrate R emission layer Cathode separator Shadow mask

ITO

G emission layer Shadow mask

ITO NPD Alq3

B emission layer Shadow mask

ITO

Small molecules are thermally evaporated in vacuum R, G, B pattering is defined by shadow masking in vacuum

Homer Antoniadis | OLED Product Development| page:15 White emitting small molecule OLEDs

Homer Antoniadis | OLED Product Development| page:16 Phosphorescent small molecule OLEDs

PHOLED technology offers significant room for further performance advances

Homer Antoniadis | OLED Product Development| page:17 The Head-Start of Small Molecule OLEDs

! Manufacturing started ! Pioneer 1997 ! TDK (Alpine, 2001) ! Samsung-NEC Mobile Display (SNMD) (2002) ! RiTdisplay (2003) ! Sanyo-Kodak (2003)

! R, G, B colors available ! limited lifetimes for blue

! Shadow masking allows easy patterning for area color ! presents challenges with scalability and high volume manufacturing

! Shadow masking challenging for full color ! high throughput and scalability is a challenge

Homer Antoniadis | OLED Product Development| page:18 Advantages of Solution Processing (Polymer) OLEDs

! Lower fabrication cost ! fewer vacuum deposition steps - lower capital cost ! advantageous materials usage and scalability (I/J printing)

! Solution processing techniques ! compatible with printing techniques - lower cost for full color ! scalable to very large substrates (high volume manufacturing) ! better mechanical integrity ! compatible with roll process for flex manufacturing

Homer Antoniadis | OLED Product Development| page:19 Full-color/Multi-color Approaches

RGB- polymer emitters Color filters Color Changing Media White emitter (CCMs)

Advantages: Advantages: Advantages: - power efficient - well-established technology (LCD) homogeneous aging of emitter (?) - lower production cost - no patterning of emitter necessary more efficient than filters - mature ITO technology - homogeneous aging of emitter (?) no patterning of emitter necessary

Disadvantages: Disadvantages: Disadvantages: ITO Sputtering on CCMs - emitters have to be optimized - power inefficient stable blue emitter necessary - ITO sputtering on filters separately (common cathode?) aging of CCMs - differential aging of emitters - efficient white emitter necessary - patterning of emitters necessary

Homer Antoniadis | OLED Product Development| page:20 Obtaining a Full Color OLED Display

1.0

0.8 0.6

0.4

0.2 0.0 Green polymer

EL Intensity (normalized) 400 450 500 550 600 650 700 750 Wavelength (nm) AM TFT screen Red polymer Ink Jet printing of R,G,B emissive polymers defines the R,G,B subpixels

(xR, yR) (xG, yG) (xB, yB) Blue polymer

R G B

Single pixel

Homer Antoniadis | OLED Product Development| page:21 Passive Matrix Addressing

Output Current

• Line by line multiplex scanning Courtesy of Philips Electronics

• Duration of addressing is 1/mux rate

• Pixel pulsed luminance = mux rate times average luminance • if 64 rows then pixel L=6400 nits for an average of 100 nits

• Limited addressed lines

Homer Antoniadis | OLED Product Development| page:22 Passive Matrix Addressing

Output Current

• Line by line multiplex scanning Courtesy of Philips Electronics

• Duration of addressing is 1/mux rate

• Pixel pulsed luminance = mux rate times average luminance • if 64 rows then pixel L=6400 nits for an average of 100 nits

• Limited addressed lines

Homer Antoniadis | OLED Product Development| page:23 Active Matrix Addressing

light

• Place a switching TFT at each pixel • Selected pixel stays on until next refresh cycle (pixels are switched and shine continuously) • Common cathode • Unlimited addressed lines

Homer Antoniadis | OLED Product Development| page:24 OLED Market will show strong growth

Worldwide OLED Market, 2000-2006 Flat panel market 2006 $57B

Value (Mio $) Thsd. units $3,500 250,000

Other value: iSuppli value: DisplaySearch $3,000 3% units: iSupply units: DisplaySearch 200,000 TFT LCD $2,500 PDP 75% 12% 150,000 $2,000 OLED $1,500 100,000 4% PM LCD $1,000 6% 50,000 Other: $500 VFD: vacuum fluorescent display EL: electroluminescence DLP: Digital Light Processing $0 0 2001 2002 2003 2004 2005 2006 2007 2008 source: iSupply/SRI 2002, Display Search 2002

Homer Antoniadis | OLED Product Development| page:25 Small Molecule Area Color Passive Matrix Displays

Motorola (by Appeal) Samsung Electronics

Examples of Wireless Products With Kodak Display Technology

Lucky Goldstar (LG)

Homer Antoniadis | OLED Product Development| page:26 Small Molecule Full Color Passive Matrix Displays Caller ID Subdisplays

Samsung Electronics Fujitsu F505i GPS 96x64 Full Color PM Display With Pioneer Full Color (4,096 colors) PHOLED 1.1-inch 96x72 pixels display. Kodak Licensed SNMD to Manufacture PM OLED Displays Phosphorescent material developed by Universal Display Corp.

Homer Antoniadis | OLED Product Development| page:27 Small Molecule Active Matrix Display Products

Eastman Kodak: Digital camera Sanyo: Cell Phone with Digital camera

Homer Antoniadis | OLED Product Development| page:28 Kodak-Sanyo 15-in flat panel display (based on white)

15-inch HDTV format (1280x720) AM a-Si OLED display by Sanyo-Kodak Full Color based on white OLED with Integrated Color Filters. The two companies showed the prototype at the CEATEC JAPAN trade show (Sep 2002).

Homer Antoniadis | OLED Product Development| page:29 Top Emitting Active Matrix OLED Display

Top Emission Adaptive Current Drive technology, allows OLEDs to be larger and higher in brightness and resolution. A 13-inch full-color AMOLED using poly-Si TFT was made where the light emits through the transparent cathode and thus, the filling factor does not depend on the TFT structure.

The schematic vertical structure of the device is substrate/TFT/metal anode/organic layers/transparent cathode/passivation layer/transparent sealing.

Display format: 800x600 (SVGA); pixel pitch 0.33x0.33mm2

Homer Antoniadis | OLED Product Development| page:30 Polymer Passive Matrix Display Products

Philips: Electrical Shaver Delta Electronics: Display for MP3 player

Homer Antoniadis | OLED Product Development| page:31 OSRAM Pictiva™ Evaluation Kit (www.pictiva.com)

San Jose, CA – May 15, 2003 -- Osram Opto Semiconductors, a global leader of solid-state lighting devices, today announced its Pictiva™ Evaluation Kit. Announced earlier this week, the Pictiva brand is Osram’s suite of organic light emitting diode (OLED) technologies. Pictiva displays offer a high level of brightness and contrast, video capabilities, wide viewing angles and a thin-profile, enabling developers and engineers to have greater design flexibility when developing the next-generation state-of-the-art electronics products.

Homer Antoniadis | OLED Product Development| page:32