Muons probe charge transport in organic semiconductors

muons probe

The propeller-shaped molecules of Alq3,which are used as an active constituent of organic light emitting diode (OLED) displays.
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Electronic devices based on organic semiconductors such as Alq3 (tris[8-hydroxy-quinoline] aluminium) are revolutionising electroluminescent displays and large-area electronics.

These organics are economically favourable, can be easily processed in large areas, have tuneable electronic properties, and are simple to grow into high quality thin films.

Even though charge transport in such organic conductors is fundamental to their operation, many of its mechanisms are still only poorly understood. Progress in this area may be pivotal to utilizing these materials to their fullest extent.

Implanted muons provide a powerful local probe for studying the dynamics of mobile spins. Muon spin relaxation studies at ISIS have been used to investigate charge carrier motion in Alq3 as a function of temperature. The charge mobilities obtained in this way are significantly larger than those obtained from direct transport measurements in polycrystalline films and thus provide an estimate for the intrinsic upper limit for the mobility that might be achievable in high quality bulk material.

 

AJ Drew (University of Fribourg, Switzerland),  FL Pratt (ISIS), NA Morley (University of Sheffield), P Desai (Queen Mary, University of London), R Scheuermann (PSI, Switzerland)

Contact: Dr AJ Drew, a.j.drew@qmul.ac.uk, Dr FL Pratt francis.pratt@stfc.ac.uk

Further reading: AJ Drew, FL Pratt et al, Phys Rev Lett 100 (2008) 116601

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