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 moiety, poly [2-(4-biphenyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole]-p-phenylenevinylene] (PPPDPV), has recently been synthesized and shown to yield much enhanced external quantum efficiency when employed in an electroluminescence (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-carrier mobilities in PPV- and PPPDPV-based EL devices.