The control of emission properties in luminescent polymers such as poly(p-phenylene vinylene) (PPV) is important for various applications, and may be achieved with suitable molecular architectures in nanostructured films. This paper reports on optical properties of PPV films, using ellipsometry measurements for emitted light in the scope of the Stokes' theory. Organized PPV films obtained with the Langmuir-Blodgett (LB) method exhibited high degree of polarization for the emitted light, while cast films emitted mainly non-polarized light. From ellipsometry data, a secondary structure was inferred for poly(xylylidene tetrahydrothiophenium) chloride (PTHT), a PPV precursor, in solution, which is retained only to a small extent in the PPV cast film as thermal conversion was performed close to the glass transition temperature of PPV. On the other hand, a higher intensity of emitted light with circular polarization was observed for the LB film, which is attributed to PPV molecular secondary structure that was enhanced during the LB film deposition. Circular dichroism experiments were performed to corroborate this hypothesis. It is suggested that such a secondary structure has not been predicted in theoretical models for PPV because possible conformational changes induced in the processing steps are not taken into account.

In this work we report the influence of the molecular orientation on the light emission polarization of poly (p‐phenylene vinylene) (PPV) films. The oriented film was processed via the Langmuir‐Blodgett (LB) technique while the non‐ordered one was processed by casting technique. By means of an ellipsometry experiment, the information about the polarization state of the emitted light was obtained via Stokes parameters and the dissymmetry factor (g). The experiments were carried out at room and low temperature (10 K) and in the phonon‐replicas range at 543 and 633 nm. We have observed a high dependence in the g factor and in the ellipticity of the emission spectra for LB films as function of the spectrum region, i. e., the phonon‐replicas. This effect is attributed to the memory of the circular polarization that is lost by thermal disorder when the emission occurs distant from the zero‐ phonon peak.

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