Absorption Studies of Charged Excitations in a-Sexithiophene

Research output: Contribution to conferencePaper


We present photoexcitation studies of vacuum deposited neutral films of .alpha..omega.-substituted sexithiophene (.alpha.-6T) using photoinduced absorption (PA) and PA-detected magnetic resonance spectroscopy (PADMR). We find evidence for photoinduced polarons having spin 1/2, with two absorption bands at 0.80 and 1.54 eV, respectively, and with negative PADMR signal at g .apprxeq.2. Similarabsorption bands are observed in lightly p-doped sexithiophene and are interpreted as due to 6T.bul.+ radical cations. In addition, a PA band is found at 1.1 eV, which is shorter lived and decreases faster with increasing temperature than the polaron bands. As similar dication bands (6T.sup.2+) have been found in heavily-doped .alpha.-6T, we identify this band as due to spinless bipolarons.Evidence of charge conjugation symmetry breaking in .alpha.-6T is presented. Finally, we have identified triplet excitons with triplet-triplet transition energy at about 1.45 eV.
Original languageAmerican English
PagesVol. 2: 1338-1342
Number of pages5
StatePublished - 1996
EventANTEC '96: Annual Technical Conference of the Society of Plastics Engineers 1996 -
Duration: 1 Jan 19961 Jan 1996


ConferenceANTEC '96: Annual Technical Conference of the Society of Plastics Engineers 1996

NREL Publication Number

  • NREL/CP-590-25344


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