Nanotransfer of the Polythiophene Molecular Alignment onto the Step-Bunched Vicinal Si(111) Substrate

Abstract

A poly(3-dodecylthiophene-2,5-diyl) film having in-plane anisotropic molecular arrangement was successfully fabricated by transferring its Langmuir-Blodgett film onto a step-bunched Si(111) substrate. Polarized near-edge X-ray absorption fine structure measurements revealed that the polythiophene main chains are preferentially orientated along periodic facet/terrace nanostructures on the step-bunched substrate, whereas less anisotropy was found on a flat substrate. The step-bunched Si substrate has been proved to be effective for controlling the in-plane molecular arrangement in the polymer thin film.

Ultrafast interface charge transfer dynamics on P3HT/MWCNT nanocomposites probed by resonant Auger spectroscopy

“…The analysis of the SP1 spectator shift parameters of the RAS spectra measured at these three photon energies shows that the electron delocalization degree of electron excited of π* symmetry (2471.9 eV) and σ* (2474.4 eV) states is higher for P3HT/ITO than P3HT/Fe-MWCNT-5%. This σ* transition presents a transition moment perpendicular to the polymer backbone, as previously discussed by H. Ikeura-Sekiguchi et al 55 and R. Onoki et al 57 However, at photon energy corresponding to the resonance maximum (2473.2 eV) the electron delocalization degree is higher for the P3HT/Fe-MWCNT-5% nanocomposite compared to P3HT/ITO. These results show that the electronic coupling between P3HT and Fe-MWCNT depends on the character of the electronic excited states.…”

Anisotropic Resonant X-ray Diffraction of a Conjugated Polymer at the Sulfur K-Edge

“…The results are shown in Figure , with f u ′ and f u ″ being applicable when the X-ray polarization is parallel to the lamellar stacking direction, f v ′ and f v ″ being applicable when the X-ray polarization is parallel to the π–π stacking direction, and f w ′ and f w ″ being applicable when the X-ray polarization is parallel to the backbone stacking direction. Based on previous observations and calculations of the X-ray absorption spectra of thiophene and thiophene-containing molecules and polymers, − the large peak in the f w ″ spectrum corresponds to the 1s → (S–C)­σ* peak whose transition dipole moment is predominantly directed along the backbone . The dominant peak in the f v ″ spectrum that is ∼1 eV lower in energy corresponds to the 1s → (S–C)­π* peak whose transition dipole moment is oriented perpendicular to the thiophene ring and hence perpendicular to the polymer backbone.…”

Combining theory and experiment for X-ray absorption spectroscopy and resonant X-ray scattering characterization of polymers

“…Even though these K edges start to go beyond the energy range of many soft X-ray beamlines, there is much interest to increase capabilities in this "tender" X-ray (2 keV-7 keV) regime. Although typically less common due to the limited number of endstations that can perform XAS or RSoXS near the sulfur and phosphorus K edges, notable work has been done on sulfur edge XAS to probe molecular orientation of semiconducting oligothiophenes such as α-sexithiophene [80][81][82], polythiophenes [83][84][85]20], and low-bandgap donoracceptor polymers [84,20,86]. Assigning the transitions near the sulfur K edge is difficult not only because of the limited body of work published, but also due to challenges such as π * and σ * peaks being very close in energy.…”