Efficient Energy Transfer to Achieve Narrow Bandwidth Red Emission from Eu³⁺-Grafting Conjugated Polymers

Abstract

A convenient approach to novel Eu 3+ -grafting conjugated polymers to achieve sharp red emission for polymeric light emitting diodes (PLEDs) has been developed in this contribution. The structure of polymer 1 is verified by FT-IR, 1 H, 13 C NMR and elemental analysis. The results indicate that efficient intramolecular Föster energy transfer depends on the overlap between the fluorescent spectrum of polymer 1 and absorption spectrum of Eu 3+ chelates. Eu(DBM) 3 is obviously the best one for accepting energy from polymer 1 among three Eu 3+ chelates to exhibit the sharp red emission. The investigation also shows that the efficiency of energy transfer relies on the content of Eu 3+ in the complexes. The investigations on the photophysical and electrochemical properties also show that the HOMO and LUMO energy levels and the band gap of complexes have no alteration with the attachment of the Eu 3+ chelate in comparison with those of polymer 1 due to the Eu 3+ chelate at the side chain of the whole molecule. The pure red electroluminescence is achieved from the fabrication of PLEDs using complex 5 as the active layer with the configuration of ITO/PVK/complex 5 /Ba/Al.