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