Thermochromism in thin films of poly(3-alkylthiophenes)

Photohole Screening Effects in Polythiophenes with Pendant Groups

“…On the basis of the photoemission results, Salaneck and co-workers 1,2 proposed that the thiophene rings are coplanar at low temperatures and the torsion angle or disorder along the aromatic backbone increases with increasing temperature, and these structure changes occur near or above room temperature. [1][2][3] From the light polarizationdependent photoemission, we infer that changes in the regioregular P3HT polymer backbone geometry occur well below room temperature for P3HT, and the structure changes are gradual. Other conducting polymers exhibit changes in the orientation of the aromatic rings in the polymer backbone with temperature similar to those reported here for P3HT, including polypyrrole, 4 so P3HT is not unusual in this regard.…”

“…[1][2][3] Temperature-dependent electronic properties coupled to backbone configuration are observed with other conducting polymers, 4,5,9 poly(3-octyloxy-4-methylthiophene), poly[2-methoxy-5-(2′-ethhexyloxy)-1,4-phenylene-vinylene] and polypyrrole. While the structural distortions contributing to thermochromism may have a profound effect upon conductivity and π-band localization of the highest occupied molecular orbitals of polymers with aromatic backbones, 6,9 the role of defects (gap states) on conductivity is often ignored or overlooked.…”

“…Changes in band gap with temperature are often observed with semiconducting polymers [1][2][3][4][5][6] and can be useful not only as optical temperature indicators but also for thermal recording. 7 Moreover, thermal control of the band gap allows for a continuous variation of electroluminence energies (wavelengths) for polymer light-emitting diodes.…”

“…1,2,6 Thermochromism has been inferred from photoemission studies of undoped P3HT, as a function of temperature, 1,2 combined with the optical absorption spectra, 2 and explained on the basis of valence effective Hamiltonian (VEH) quantum chemical calculations, 1,11 without invoking chemical defects.…”

Enhanced nonlinear absorption and optical limiting in semiconducting polymer/methanofullerene charge transfer films

“…The origin of such an intensity dependence can be a higher order negative nonlinearity, possibly nonlinear bleaching due to the thermochromic effect in P3OT. 14 The damage threshold was around 15 J/pulse (ϳ1 J/cm 2 in average fluence͒, above which there is a permanent change in the linear transmission.…”