o rganic l ight e mitting d iodes andrew sanders, fawzi salama, john p. handrigan 12/02/2010

ORGANIC LIGHT EMITTING DIODES

Andrew Sanders, Fawzi Salama, John P. Handrigan12/02/2010

Outline

Introduction How OLEDs work? Materials Fabrication Techniques Recent Developments Conclusions

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Introduction3

Applications

http://en.wikipedia.org/wiki/File:OLED_EarlyProduct.JPG

http://www.newlaunches.com/entry_images/1107/14/sony_xel2-thumb-450x337.jpg

http://www.hitech-projects.com/euprojects/olla/downloads/pictures/olla_4generations.jpg

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Advantages

Low power consumption

Flexible displays (with polymer layer)

High Contrast (1,000,000:1)

Thin Displays (3mm)

Thin organic Layer (100 -150 nm)

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History

Commercialization of inorganic LEDs in

1960’s

OLEDs using small molecules

Tang and Van Sylke from Kodak (1987)

Discovery of electroluminescence from

polymers

J. H. Burroughes et al. (1990) at University

of Cambridge

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How OLEDs WorkOrganic Semiconductivity

SMALL MOLECULE TYPE POLYMER TYPE

Aluminum oxinate Polyphenylene vinylene

http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?sid=24868131

http://upload.wikimedia.org/wikipedia/commons/9/94/Polyphenylene_vinylene.png

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How OLEDs WorkStructure

Electrons (-)

Electron-holes (+)

http://www.sigmaaldrich.com/materials-science/material-science-products.html?TablePage=19353440

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HOMO(valence band)

Electron Holes (+)

Electrons (-)

Emissive Layer

ΔE=h/ (λc)

LUMO (Conduction band)

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How OLEDs WorkElectroluminescence

Configuration

Substrate Glass, PET

Anode ITO, Polyaniline

Cathode Ca, Mg-Ag, Al-Li

HTL ETL

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http://www.sigmaaldrich.com/materials-science/material-science-products.html?TablePage=19353440

Anode Substrate HTL

Cathode

EML ETL

EML Materials11

Properties Semi-conductor Radiative recombination dominates due to

large energy level 3 basic colors 2 types

Small Molecules Polymers

Photo Emitting Materials

Small Molecules Green: Alq3 Blue:

Distyrylarylenes Red: Rubrene

Polymers Green: PPV Blue: PPP’s, PFO’s Red: PT’s, P3ATs

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Rubrene

Alq3Distyrylarylene

PPV

PPP PT

Fabrication Techniques13

Wet Techniques Inkjet Printing

Dry Technique Vacuum Thermal Evaporation Organic Vapour Phase Deposition

Fabrication Techniques:Inkjet Printing

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Advantages Solution for large

area deposition Disadvantages

Deposited film is non-uniform

Fabrication Techniques:Vacuum Thermal Evaporation

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Advantages High film uniformity Vacuum equipment is

available Disadvantages

Organic build up on chamber walls

Expensive

Fabrication Techniques:Organic Vapour Phase Deposition

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Fabrication Techniques:Organic Vapour Phase Deposition

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Advantages High uniformity Reduced organic material consumption Does not require high-vacuum conditions

Disadvantages Expensive equipment

Market18

Current Research

Phosphorescent materials Device lifetime Application to solar cells

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Conclusions

Young technology Enormous progress on materials and

fabrication techniques Growing technology for electronics

display With lower costs, the best technology to

adopt

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Questions?

Thank you