Synthesis and luminescence properties of new blue-light-emitting polyconjugated poly{1,1′-biphenyl-4,4′-diyl-[1-(4-t-butylphenyl)] vinylene} polymers and copolymers

Three new soluble polyconjugated polymers, all of which emitted blue light in photoluminescence and electroluminescence, were synthesized, and their luminescence properties were studied. The polymers were poly{1,1′- biphenyl-4,4′-diyl-[1-(4-t-butylphenyl)]vinylene(, poly((9,9- dioctylfluorene-2,7-diyl)-alt-{1,4-phenylene-[1-(4-t-butylphenyl)vinylene-1, 4-phenylene]}) [P(DOF-PVP)], and poly([N-(2-ethyl) hexylcarbazole-3,6-diyl]-alt- {1,4-phenylene-[1-(4-t-butylphenyl)]vinylene-1,4-phenylene}). The last two polymers had alternating sequences of the two structural units. Among the three polymers, P(DOF-PVP) performed best in the light-emitting diode devices of indium-tin oxide/poly(ethylenedioxythiophene) doped with poly(styrene sulfonate) (30 nm)/polymer (150 nm)/Li:Al (100 nm). This might have been correlated with the balance in and magnitude of the mobility of the charge carriers, that is, positive holes and electrons, and also the electronic structure, that is, highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) levels, of the polymers.