Large magnetoresistance at room-temperature in small-molecular-weight organic semiconductor sandwich devices

We present an extensive study of a large, room temperature magnetoresistance (MR) effect in tris-(8-hydroxyquinoline) aluminum sandwich devices. The effect is similar to that previously discovered in π-conjugated polymer devices. We characterize this effect and discuss its dependence on magnetic field direction, voltage, temperature, film thickness, and electrode materials. The MR effect reaches almost 10% at fields of 10 mT at room temperature. The effect shows only a weak temperature dependence and is independent of the sign and direction of the magnetic field. Measuring the devices' current-voltage characteristics, we find that the current depends on the voltage through a power-law. We find that the magnetic field changes the prefactor of the power-law. We also studied the effect of the magnetic field on the electroluminescence (MEL) of the devices and analyze the relationship between MR and MEL.