Photophysical and electroluminescent properties of a Series of Monochromatic red-emitting europium-complexed nonconjugated copolymers based on diphenylphosphine oxide modified polyvinylcarbazole

Two novel copolymers P1 and P2 were prepared by using the polymerizable aryl phosphine oxide based Eu(TTA)₃VBCzDPO (EuM) (VBCzDPO = 3,6-bis(diphenyl-phosphoryl)-9-(4- vinylbenzyl)-9H-carbazole) and vinylcarbazole as the monomers with the compositions of 1:99 and 1:33, respectively. It is showed that the stronger coordinate ability of bidentate APO ligands facilitates the stability of the complex monomer during polymerization, and their beetling coordinate sites and adjustable structure efficiently reduce the steric effect of bulky EuM. Both of photoluminescent (PL) spectra in solution and solid of the copolymers exhibited improved emission from Eu³⁺ ion. The high PL quantum yield (PL QY) in solid of 60% is realized. Further investigation indicates that for the intra-chain energy transfer VBCzDPO serves as the intermediate and bridge between PVK and Eu(TTA)₃, which ensures the high efficiency of whole intra-chain energy transfer. The pure-red emission from the devices of P1 and P2 was demonstrated.