Control of magnetoconductance through modifying the amount of dissociated excited states in tris-(8-hydroxyquinoline) aluminum-based organic light-emitting diodes

摘要

Magnetoconductance (MC) is generally believed to be controlled by the ratio of singlet to triplet excited states. In this study, it is found that the MC magnitude of tris-(8-hydroxyquinoline) aluminum-based organic light-emitting diodes decreases substantially upon the introduction of narrow band gap fluorescent dopants. Since singlet to triplet ratio of excited states keeps unchanged in doped devices, this large reduction in MC means that other underlying mechanism affects the MC. The charge carrier trapping effect is proposed here to vary the magnitude of MC. By using this trapping effect, the controlling of the total amount of dissociated electron-hole pairs and consequently the magnitude of MC are realized by changing the dopant's concentration or band gaps.