Experimental investigation on the origin of magneto-conductance and magneto-electroluminescence in organic light emitting devices

We investigate the underlying mechanisms of the magnetic field effects (MFEs), magneto-conductance (MC) and magneto-electroluminescence (MEL), in organic semiconductors by testing three kinds of devices, the electron-only devices, the hole-only devices and the ambipolar devices. There is no or very small MCs in the unipolar devices and much larger MC in the ambipolar devices. The results suggest that the ambipolar injection or exciton formation is a dominant factor to obtain large MCs, and the MEL is in principle a primary effect. Our results are consistent with the electron–hole pair model.

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► Hole-only devices, electron-only devices, and bipolar devices were fabricated.
► The magneto-conductance (MC) and magneto-electroluminescence (MEL) of the three kinds of devices were tested.
► No or very small MCs in the unipolar devices and much larger MC in the bipolar devices.
► Exciton formation is a dominant factor to obtain large MC.
► The MEL is in principle a primary effects and the MC comes from the MEL.