THERMOCHROMIC PROPERTIES OF QUATERTHIOPHENE, AN ALKYL-SUBSTITUTED QUATERTHIOPHENE DERIVATIVE AND ITS CORRESPONDING POLYMER

We report for the first time the thermochromic properties of a substit uted oligothiophene. The temperature-dependent absorption spectra of 3 ',4 ''-didecyl-2,2':5',2 '' :5 '',2'''-quaterthiophene (DDQT) show the appearance of a red-shifted band that is caused by conformational cha nges. The changes in the optical properties of DDQT are compared with those observed in the unsubstituted quaterthiophene (QT). In the latte r, a parallel type excitonic model is used to explain the changes in t he optical spectra. The thermochromism of DDQT is also compared with t hat of the corresponding polymer (PDDQT). For all compounds, the fluor escence spectra also show a new red-shifted band. The origin of this n ew emission is discussed. (C) 1998 Elsevier Science B.V. All rights re served.