PHOTOINDUCED ABSORPTION STUDY OF SEXITHIOPHENE - EVIDENCE FOR PHOTOGENERATION OF POLARONS

We have studied films of neutral 6T using photoinduced absorption spec troscopy. Two pairs of strong and weak narrow absorption lines are obs erved at 0.80 (strong), 0.96 (weak) and 1.54 (s), 1.68 (w) eV, respect ively. They are very similar in energy, width and shape to those found in the radical cation 6T(.+). We therefore assign them to long lived photoinduced polarons (radical ions). The observed polaron spectrum is in very good agreement with energy level calculations of 6T. In addit ion, there is a weak separate line at 1.1 eV that is close in energy t o the position of the dication related band (1.2 eV).