Eu-doped cholesteric mixtures with a highly thermosensitive circular polarization of luminescence

Abstract

A novel approach of the temperature measurement by recording the dissymmetry factor temperature dependence of the cholesteric mixtures doped with luminescent europium complex is developed. The cholesteric mesophase possesses the unique optical properties, one of which is the selective reflection of circularly polarized light with a wavelength proportional to the helix pitch. For the cholesteric systems doped with luminescent molecules, whose emission overlaps with the selective light reflection peak, the luminescence becomes circularly polarized in the direction opposite to the direction of polarization of the reflected light. We proposed to use the cholesteric material, containing highly emissive Eu complex doped into temperature-sensitive cholesteric mixtures with suitable spectral range of selective light reflection peaks, for temperature sensing. The sensitivity of the obtained system reached 4.4%/K in the near-physiological range.