Large magnetoresistance at room temperature in semiconducting polymer sandwich devices

A thin-film-sandwich device is fabricated consisting of poly(9,9-dioctylfluorenyl-2,7-diyl) sandwiched between two electrodes to study magnetoresistance (MR) effect in semiconducting polymer OLEDs. MR measurements at room temperature for different voltages show that MR traces are independent of the temperature and the angle between film plane and applied magnetic field. However a dependence on the film thickness is observed for an increase in turn-on voltage with increasing film thickness. Hence, MR effect is a bulk rather than an (electrode) interface effect.