Trivalent europium complex nanocrystals: Fine-tuning luminescence property with micellar dipole vector shell for fingerprints

Abstract

Eu(III) complexes are intrinsically highly luminescent materials. However, their luminescence is strongly quenched by solvent molecules. To address this issue, we herein present a micellar dipole vector shell strategy to against penetration of solvent molecules going through micellar shell and into Eu(III) complex nanocrystals (NCs). The micellar dipole vector shell is constructed upon formation of reverse micelles with ordered arrangement of dipole amine based surfactant molecules. Magnitude of the micellar dipole vector is finely tuned by methylation of octadecylamine (ODm). Going from N,N-dimethyloctadecylamine (DMODm) to N-methyloctadecylamine (MODm) and ODm, magnitude of dipole moment of surfactant increases from 0.45 D to 0.99 D and 1.50 D, hence, establishing a higher barrier to against penetration of solvent molecules with reduction of nonradiative relaxation and enhancement of radiative emission. As results, photoluminescence quantum yields (PLQYs) of the Eu(III) complex (Eu-1) NCs increases from 4.6% to 12.4% and 15.1% and the exciton binding energy goes from 226.0 meV to 462.2 meV and then 542.2 meV. Potentiality Application of this approach is again confirmed with construction of Eu(III) NCs from Eu-2. In all, our results demonstrate that covering the trivalent europium complex NCs with a micellar dipole vector shell is a new solution to enhance their luminescence.