Structural features in aligned poly(3-alkylthiophene) films revealed by grazing incidence X-ray

The structural ordering in as-spun and rubbed (then annealed) thin films of poly[(3-hexylmethoxy)thiophene] has been investigated by means of grazing incidence X-ray diffraction (GIXRD) and the results have been compared with the structural data as obtained from XRD on powder samples. In the structure of the as-spun films the thiophene rings in the backbone lie parallel to the plane of the interface with a welldefined separation among the chains of 19 A ° . Rubbing the films creates a unique direction in which the domain size is increased, whereas ordering normal to the rubbing direction is greatly diminished, leading to dichroic behavior. Annealing the films at 95 8C seems to have no significant effect on the ordering thereafter.