Luminescent Liquid Crystalline Composites Based on Lanthanide(III) Complexes and Paramagnetic Quantum Dots

Abstract
The main practical property of liquid crystals (LC) is the possibility of obtaining of ordered media with uniaxial arrangement of molecules and with the ability to control their orientation using electric and magnetic fields. Due to this ability, they are widely used in various devices of molecular electronics. In recent years, in addition to the synthesis of a large number of new compounds, considerable attention of scientists has been attracted by the possibility of introducing various dopants into LC media, which can potentially become a cost-effective way to improve the parameters of LC indicators. Organometallic complexes, metallic NPs, semiconductor NPs, ferroelectric NPs, and dielectric NPs can act as components of LC mixtures. In this work, we studied the effects of introducing a mesogenic europium(III) complex and paramagnetic quantum dots into commercially available LC media. LC materials with separated excitation maxima were obtained, which made it possible to selectively sensitize the luminescence of the LC mixture, quantum dots, and the Eu(III) complex. Thus, by varying the luminescence excitation wavelength in the range from 340 nm to 390 nm, it is possible to obtain various luminescence colors, including white. Such materials can find practical application in tunable lasers, organic light emitting diodes, and other information processing and display devices.

Keywords: liquid crystals, europium(III) complex, paramagnetic quantum dots, luminescence