Correlation between emission and structural properties of poly(p-phenylene vinylene) thin films

• PPV thin films with different structural properties were analyzed by optical spectroscopy.
• The PL lineshape and emission anisotropy were dependent of structure of the film.
• Distinct optical properties were related to excitation migration processes.
• Excitation migration is crucial for analysis of the optical response of thin films.

In this work we used different methods and parameters of deposition in order to obtain thin films of poly(p-phenylene vinylene) (PPV) with different structural properties. These properties were characterized by measurements of absorbance, Raman scattering, and photoluminescence (PL) as a function of temperature. The analysis of experimental data allowed us to observe the dependence of optical spectra with the effective conjugation length and the interaction between the polymer chains. In particular, we were able to correlate the dependence of the PL line shape with temperature and the values of emission anisotropy factor of the films with the intra and interchains energy migration processes. These results led us to conclude that such processes are essential ingredients for a proper analysis of the optical response of thin films of conjugated polymers.