Novel polymeric light-emitting devices based on bipolar copolymers containing quinoline aluminum moieties and N-vinylcarbazole segments

A series of bipolar copolymers containing quinoline aluminum moieties and N-vinylcarbazole segments exhibited excellent photoluminescence performance and improved hole-transporting ability, were used as light-emitting materials to fabricate polymeric light-emitting devices (PLEDs). Six simple devices with structure of ITO/PEDOT (40 nm)/copolymer (80 nm)/CsF (1.5 nm)/Al (120 nm) were fabricated by solution spin-coating. These devices gave dominant yellow-green emission from quinoline aluminum with excellent stability. Together with electrochemical data, the electroluminescence (EL) mechanism of the devices was studied. Moreover, effects of substituted group and quinoline aluminumʹs content on the EL properties of the devices were investigated in detail. The results indicate that the device based on the copolymer (P2-1) with substituted group of carbazole and 2 mol% quinoline aluminum possess optimal EL properties with a maximum luminance of 487 cd/m2 and a peak current efficiency of 0.545 cd/A.