Thermo-switchable Imaging Medium Achieving Both Emissive Reflective Modes

A multifunctional composite film that exhibited thermoresponsive absorption and emission was fabricated using a thermochromic leuco dye, its developer, and a luminescent Europium(III) complex. The emissions from and coloration of this composite film could be reversibly changed and maintained via the thermochromic reaction taking placing within the leuco dye developer system. The coloration and decoloration of the composite film were caused by thermoresponsive control of the nanoscale aggregation of structures of the leuco dye and its developer, whose molecular structure consisted of a long alkyl chain. The control of the phenomenon of photoluminescence could also be achieved via thermochromism, which was induced by intermolecular energy transfers from the Eu(III) ions in the excited states to the leuco dye.