CARRIER DEEP-TRAPPING MOBILITY-LIFETIME PRODUCTS IN POLY(P-PHENYLENE VINYLENE)

In order to estimate the deep-trapping mobility-lifetime (mutau) produ ct for holes and electrons in poly(p-phenylene vinylene) (PPV), trap-f ree space-charge-limited current, and time-of-flight measurements were performed on bilayer devices comprising of a PPV layer and a trap-fre e molecularly doped polymer layer. Mutau products of about 10(-9) and 10(-12) cm2/V were found for holes and electrons respectively, corresp onding to an average range of 1 mum for holes and 10 angstrom for elec trons under an electric field of 10(5) V/cm. The low mutau value for e lectrons is attributed to severe deep trapping of electrons in PPV, ef fectively reduces their range. Implications on the efficiency of elect roluminescence devices are discussed. (C) 1994 American Institute of P hysics.