Temperature Dependence of the Absorption Spectra of Bithiophene and Terthiophene Isolated Molecules in Cyclodextrin

Abstract

The temperature dependence of the absorption spectra of 2,2 0 -bithiophene and 2,2 0 :5 0 ,2 00 -terthiophene isolated molecules in cyclodextrin (CyD) were investigated between 15 K to room temperature (RT). The optical absorption spectra of BT molecules inand -CyD, (BT) -CyD and (BT) -CyD are nearly the same between 15 K and RT. Those of TT are almost the same for (TT) -CyD and (TT) -CyD . Anomalous temperature dependence of the absorption intensities was observed. The absorption intensities of the isolated molecules of BT and TT in CyD, (BT) CyD and (TT) CyD increase with increasing temperatures. The s-trans states of (BT) CyD and (TT) CyD convert to the s-cis states at high temperatures through the rotational vibration around the single bond between thiophene rings. The allowed transition of the s-cis conformation would mix to the forbidden transition of s-trans conformation, thus the absorption intensity increases at high temperatures.

Surface exciton in thiophene oligomer single crystals

“…We succeeded in measuring them with normal incident light by growing thick SCs. They are identical to those reported in 4T and 5T, which were measured at oblique incident angles to the well‐grown flat crystal planes and analyzed with the oblique angle dependent Kramers–Kronig formula 5, 21, 23–32, 34–36.…”

“…These fine structures are so‐called vibronic excitons which are coupled with breathing mode vibrations. These series of the fine peaks are more clearly observed than those of 2T and 3T single molecules in cyclodextrins 34, 35.…”

Theoretical study of thiophene oligomers for photovoltaics: thiophene-furan for films and cyanoacrylated thiophene as sensitizer for ZnO

“…As discussed before for the electronic gaps, also here, the exciton binding energies (E B ), and consequently, the optical gaps (E opt ) for the thiophene-furan co-oligomers are more strongly dictated by thiophene than by furan. We see this behavior by comparing the first optical excitation for the dimers in Figure 3.8, namely, the 3.5) and the blue horizontal bars are an estimate of the relative peak intensities [6,11,81,82,83,93,94,95].…”

“…The blue solid curves are an estimate of the absorption spectra of the molecules using Lorentzian functions with a scale parameter of 0.1 eV. The blue arrows indicate the position of the experimental absorption peaks (see Table3.5) and the blue horizontal bars are an estimate of the relative peak intensities[81,82,83].…”