Quenching of the Magnetic Field Effect on the Photocurrent and Photocurrent Detected Magnetic Resonance in Conjugated Polymer-Fullerene Diodes

We have studied the effect of a magnetic field on the photocurrent of MDMO-PPV (poly(2-methoxy,5-(3',7'-dimethyloctyloxy)-1,4-phenylenevinylene) and MDMOPPV/fullerene diodes (plastic solar cells) and performed photocurrent detected magnetic resonance (PCDMR) experiments on these devices consisting of an active layer sandwiched between a low and a high workfunction metal electrode. Results clearly show that the magnetic field effect (MFE) on the photocuttent as well as PCDMR signals are quenched in conjugated polymer/fullerene composite devices in contrast to large signals observed in the pristine conjugated polymer devices. Photoinduced electron transfer from conjugated polymers onto fullerene is proposed to be responsible for this quenching.