Raman scattering as a probe of morphology in conjugated polymer thin films

Polarized confocal Raman mapping is used to characterize the degree of molecular alignment in spin coated conjugated polymer thin films. To this end, the polarization selection rules of a specific Raman active mode are employed to infer indirectly the local molecular alignment. The film can be monitored and characterized with a diffraction limited spatial resolution fixed by the microscope optics. In addition, we demonstrate examples of characterization of molecular alignment in highly oriented samples by monitoring the angular dependence of the polarized Raman signal. Finally, we show the use of temperature dependent Raman scattering to monitor thermal phase transitions in bulk conjugated polymer samples. These procedures can be used as in situ characterization methods in a wide variety of experimental situations and offer a sensitive probe of processing protocols used in the fabrication of polymer optoelectronic devices.