Time-of-flight measurements of charge-carrier mobilities in a poly (p-phenylenevinylene) derivative carrying an electron-transporting moiety

A poly (p-phenylenevinylene) derivative carrying an electron-transporting m oiety, poly [2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole]-p-phen ylenevinylene] (PPDPV), has recently been synthesized and shown to yield mu ch enhanced external quantum efficiency when employed in an electroluminesc ence (EL) device. As the mobility balancing of positive and negative charge carriers plays a main role in the EL efficiency, we have carried out time- of-flight (TOF) measurements for separate determination of the two charge-c arrier mobilities in PPV- and PPPDPV-based EL devices.