Thermosensitive chameleon films based on polystyrene doped with complexes of europium(III) and terbium(III)

Abstract

New complexes of Eu(III) and Tb(III) tris(β-diketonates) with Lewis bases were synthesized. The spin-coating technique was used to produce composite films consisting of polystyrene (PS) polymer doped with mixtures of Eu(III) and Tb(III) complexes with different ratio of luminophores. An increase in the content of the Tb(III) complexes in the 5 %Eu x%Tb films intensifies emission of both the Tb3+ and Eu3+ ions due to occurring intermolecular energy transfer and leads to a significant increase in photostability of the material (the loss of luminescence intensity ratio did not exceed 0.5 %/hour). These photostable films were characterized as potential luminescent temperature sensors. The temperature sensitivity of their luminescence intensity and lifetime was investigated in the range of 298–383 K. The maximum absolute sensitivity of the films reaches 6.00 µs/K and exceeds that of all known lanthanide-containing thermal sensors designed for measuring physiological temperatures. In combination with changeable luminescence colors of the films, such a sensitivity makes these materials promising colorimetric thermal sensors for in situ temperature measurements.