New fluorescent polyimides, having an electroluminescent (EL) active u
nit, 2,5-distyrylpyrazine (DSP), were synthesized by the polycondensat
ion of 2,5-bis(4-aminostyryl) pyrazine 4 with various tetracarboxylic
dianhydrides 5, Intense photoluminescence originating from the DSP chr
omophore units was demonstrated. Furthermore, a light emitting diode (
LED) was fabricated based on the polyimide Langmuir-Blodgett him, usin
g indium tin oxide and a Mg-Ag alloy as the anode and the cathode, res
pectively. tinder forward bias, orange-red light emission (lambda(max)
= 560 nm) could be observed, which was similar to the emission genera
ted by photoexcitation. Meanwhile the EL intensity linearly depended o
n the applied current density, which indicated that light emission res
ulted from recombination of the injected charges in the polyimide laye
r.