Europium amphiphilic naphthalene based complex for the enhancement of linearly polarized luminescence in Langmuir–Blodgett films

Abstract

Linearly polarized luminescence (LPL) in films of europium ions was induced by using naphthoic acid adopted alkyl chain (NaphC15), which plays the roles of both surfactant and photo-antenna. The synthesis of NaphC15 was newly developed, and the Eu complex composed in a 1 : 3 ratio of Eu³⁺ ion and NaphC15 was synthesized in the powder form for comparison. The structural aspects of LB films with a layered scheme were obtained from the measurements of synchrotron XRPD, X-ray photoelectron spectroscopy and waveguide polarized absorption spectra. Luminescence of europium in the film is more intense than that in the powdered complex. The luminescence efficiency calculated from the observed luminescence lifetimes and quantum yields also supported their structure-enhanced luminescence. Finally, we revealed that the LPL was sensitized by the electronic dipole moment localized on the NaphC15 moieties aligned independently in the Langmuir–Blodgett films.