Study of magneto-electroluminescence and magneto-conductance in polymer light-emitting electrochemical cells

Magneto-electroluminescence (MEL) and magneto-conductance (MC) have been investigated in polymer light-emitting electrochemical cells based on ?super-yellow? poly-(phenylene vynilene) (SY-PPV). We measured positive MEL(B) and MC(B) responses that show a modified Lorentzian shape for B < 120 mT. At B < 2 mT, both MEL(B) and MC(B) responses show a second component, opposite in sign to the higher field response. We interpret the magnetic field response using the polaron pair model, from which we extract the hyperfine interaction constant of polarons in the SY-PPV polymer.