title: Magnetoconductivity and magnetoluminescence studies in bipolar and almost hole-only sandwich devices made from films of a π-conjugated molecule.
abstract: We present magnetoconductivity and magnetoluminescence measurements in sandwich devices made from films of a π-conjugated molecule and demonstrate effects of more than 30 and 50% magnitude, respectively, in fields of 100 mT at room-temperature. It has previously been recognized that the effect is caused by hyperfine coupling, and that it is phenomenologically similar to other magnetic field effects that act on electron-hole pairs, which are well-known in spin-chemistry. However, we show that the very large magnitude of the effect contradicts present knowledge of the electron-hole pair recombination processes in electroluminescent π-conjugated molecules, and that the effect persists even in almost hole-only devices. Therefore, this effect is likely caused by the interaction of radical pairs of equal charge.
authors.affiliation: Department of Physics and Astronomy and Optical Science and Technology Center, University of Iowa, Iowa City, IA 52242-1479, USA.
authors.forename: Tho
authors.initials: T
authors.lastname: Duc Nguyen
authors.affiliation: Department of Physics and Astronomy and Optical Science and Technology Center, University of Iowa, Iowa City, IA 52242-1479, USA.
authors.forename: Yugang
authors.initials: Y
authors.lastname: Sheng
authors.affiliation: Department of Physics and Astronomy and Optical Science and Technology Center, University of Iowa, Iowa City, IA 52242-1479, USA.
authors.forename: James E
authors.initials: JE
authors.lastname: Rybicki
authors.affiliation: Department of Physics and Astronomy and Optical Science and Technology Center, University of Iowa, Iowa City, IA 52242-1479, USA.
authors.forename: Markus
authors.initials: M
authors.lastname: Wohlgenannt
keywords: hyperfine coupling; magnetic field effect; organic magnetoresistance; radical pair mechanism