Transient and AC Electroluminescence in Pyridylene Copolymers of PPV

We present transient and AC electroluminescence (EL) measurements on thin films of a newly synthesized copolymer of PPV where pyridine units were incorporated into the polymer backbone (co(PyPV)), and compare it to the EL of thin films of PPV prepared by the method of self-assembly and by spin casting. Transient EL under voltage pulses of co(PyPV) indicates that positive charge carriers have lower mobility than in PPV. Under pulses and AC square wave voltage we have observed a new type of prompt transient EL at the switch-off of the voltage. The transient EL effects are explained by the presence of non-bonding electrons in the polymer chain of co(PyPV). Co(PyPV) based LEDs have improved EL yield compared to PPV. Operations with sine AC voltage mode up to 10 kHz show better stability as compared to DC, without loss in efficiency.