Luminescence probing of crystallization in a polymer film

摘要

We report studies of a thin film multilayer stack including a highly emissive substituted polythiophene, poly3-(2,5-dioctylphenyl)thiophene. Analysis of the photoluminescence spectra revealed an inhomogeneous polymer film. X-ray diffraction studies attribute the existence of an inhomogeneous film as originating from crystallization of the polymer. We used the interference effect of light to detect the region of crystallization in the film. Photoluminescence and absorption were redshifted upon crystallization and displayed an enhanced vibronic structure. Comparison between calculated and measured photoluminescence shows that the crystallization starts from the top of the film and not from the supporting substrate.