NEW FLUORESCENT POLYIMIDES FOR ELECTROLUMINESCENT DEVICES BASED ON 2,5-DISTYRYLPYRAZINE

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.