polymere light emitting diode - fh-muenster.de · light‐emitting polymers • by substituting a...
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PLEDPLEDPolymere Light Emitting Diodey g g
Lecture: Incoherent Light SourcesLecture: Incoherent Light Sources SS 2013
Adrian Podlinski
Differentiation of OLEDsDifferentiation of OLEDs
• SMOLED (small molecule organic light‐emitting diodes)g )
PLED (P l li h i i di d )• PLED (Polymer light‐emitting diodes)
• PHOLED (Phosphorescent organic light‐itti di d )emitting diode)
StructureStructurePLEDPLED
LEP: Light‐emitting PolymerLEP: Light emitting PolymeriL: InterlayerHiL: Hole Injection Layer
Semiconducting PolymersSemiconducting Polymers
• Conjugated‐π‐Electron‐System• Contiguous sp2 hybridized carbon centersContiguous sp hybridized carbon centers• P‐orbitals form a one‐dimensional electronic b dband
• Higher conductivity higher degree of g y g gcrystallinity and better alignment of the chains
Light Emitting PolymersLight‐Emitting Polymers
• PPV was suggested for lighting application in 1990
• Synthesis:
Light Emitting PolymersLight‐Emitting Polymers
• By substituting a polymer different properties can be changed, like:g– StabilitySolubility– Solubility
– Conductivity– Emission spectrum
FabricationFabrication
k i i• Ink‐Jet‐Printing
+ High resolution + Large area‐Uneven Emission because of different layer thicknesses
FabricationFabrication
i i• Spin‐Coating
+ Uniform films+ Simple R&D process‐ High wastageHigh wastage‐ Not ideal for big production quantities
Phosphorescent OLEDsPhosphorescent OLEDs
• 2 types of excitons are possible – statistical ratio singlet:triplet =1:3g p
Phosphorescent OLEDsPhosphorescent OLEDs
• In order for triplet excitons to emit, spin‐orbit coupling is requiredp g q
• This effect is strong in heavy atomsT i i l did• Transition metals are common candidates to enable phosphorescence from organicmolecules
• Doping a host polymer with• Doping a host polymer with an organometallic complex
AdvantagesAdvantages
• Light weight & flexible plastic substrates• Wider viewing angles & improved brightnessWider viewing angles & improved brightness• Better power efficiency and thickness• Response time
DisadvantagesDisadvantages
• Lifespan• Color balance issuesColor balance issues• Outdoor performance• High Cost• Power consumption increases for whitePower consumption increases for whiteimages
SourcesSources
htt // l d i f /• http://www.oled‐info.com/• http://www.cdtltd.co.uk/
// /• http://www.sigmaaldrich.com/technical‐documents/articles/material‐matters/light‐emitting polymers htmlemitting‐polymers.html
• http://www.nobelprize.org/nobel_prizes/chemistry/laureates/2000/advanced‐ry/laureates/2000/advanced‐chemistryprize2000.pdf
• http://www nature com/nature/journal/v347/n6http://www.nature.com/nature/journal/v347/n6293/pdf/347539a0.pdf