• Sol–gel processes;
  • Organic–inorganic hybrid composites;
  • Ionic liquids;
  • Lanthanides;
  • Luminescence


Herein, we report a facile method to prepare thermally reversible, flexible, transparent, and luminescent ionic organosilica gels with tunable emission colors. The reaction of an amino-functionalized ionic liquid ([NH2-Bim]Br) with 3-(triethoxysilyl)propyl isocyanate results in an ionic-liquid-modified alkoxysilane, the hydrolysis and condensation of which lead to thermally reversible, flexible, and luminescent ionic gels in the presence of lanthanide species. The luminescence color can be fine-tuned by changing the Ln3+ ions (Eu3+, Tb3+, or a mixture of Eu3+ and Tb3+) and by changing the excitation wavelength. The absolute quantum yields of the flexible luminescent gels with europium(III) and terbium(III) complexes are determined to be 15 and 21 %, respectively, by using an integrating sphere. The thermal reversibility of the organosilicas makes them attractive for the development of flexible optical devices and flexible luminescent devices such as organic light-emitting diodes (OLEDs).