G Veeraraghavan et al 2007 J. Phys.: Condens. Matter 19 036209 doi:10.1088/0953-8984/19/3/036209
G Veeraraghavan1, T D Nguyen2, Y Sheng2, O Mermer2 and M Wohlgenannt2,3
Show affiliationsWe report on the experimental characterization of a recently discovered large magnetoresistive effect in polyfluorene and in Alq3 organic light-emitting diodes. We also observe similar magnetic field effects (MFEs) of comparable magnitude in electroluminescence and photocurrent measurements. We provide a comprehensive overview of all these three types of MFE. To the best of our knowledge, the mechanism causing these MFEs is not currently known with certainty. Moreover, we show that experiments in bipolar, electroluminescent devices do not allow determination of whether the MFE acts on the carrier density or carrier mobility, making any attempt at explaining it ambiguous. As a remedy, we perform magnetoresistance measurements in hole-only polyfluorene devices and show that the MFE acts on the carrier mobility rather than carrier recombination.
85.60.Jb Light-emitting devices
85.60.Bt Optoelectronic device characterization, design, and modeling
72.20.My Galvanomagnetic and other magnetotransport effects
Issue 3 (24 January 2007)
Received 22 June 2006, in final form 21 November 2006
Published 5 January 2007
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