The optical properties of various PEDOT:PSS films obtained by drop casting and blade coating are analyzed by variable-angle spectroscopic ellipsometry in the visible-UV spectral range. We discuss observed differences in the optical spectra due to PSS content and DMSO treatment and correlate them to structural changes extracted from Raman measurements. In particular, we investigate the optical anisotropy of the complex refractive indices which arises from the in-plane arrangement of the PEDOT backbones, giving rise to optically uniaxial behavior with the optic axis perpendicular to the film plane. Although this is widely accepted, most investigations disregard the anisotropy for simplicity, which sometimes leads to inaccurate conclusions. In this work, we compare the results of isotropic and anisotropic analyses to clarify which kind of errors we can expect if anisotropy is not considered. Finally, the correlation between Raman scattering and ellipsometric analyses shows that not only local structural changes of the chain conformation but also the overall morphology of the composite films are significant in the interpretation of Raman spectra.

Sb2S3 powder was successfully synthesized by solid state reaction technique using high-purity elemental antimony and sulfur. Sb2S3 thin films were deposited on unheated glass substrates by one step thermal evaporation and annealed under vacuum atmosphere for 2 hours at different temperatures 150, 200 and 250 °C. Different characterization techniques were used to better understand the behavior of the Sb2S3 material. X-ray diffraction (XRD) and Raman spectroscopy confirmed the formation of pure Sb2S3 powder with lattice parameters a = 11.07 Å, b = 11.08 Å and c = 3.81 Å. The effect of vacuum annealing temperature on the properties of the films was studied. XRD analysis revealed that as-deposited and annealed films at 150ºC were amorphous in nature whereas those annealed at T ≥ 200°C were polycrystalline with a preferred orientation along (201) plane. The crystallite size of the polycrystalline films showed a decrease from 75.8 to 62.9 nm with the increase of the annealing temperature from 200 to 250 °C. The Raman analysis showed several peaks corresponding to the stibnite Sb2S3 phase. The surface morphology of the films was examined by atomic force microscopy (AFM). The surface roughness decreases slightly as the transformation from the amorphous to the crystalline phase occurs. The chemical compositions of Sb2S3 films were analyzed by energy dispersive X-ray spectroscopy (EDS), revealing that all films were Sb-rich. The optical parameters were estimated from the transmittance and reflectance spectra recorded by UV-Vis spectroscopy. A reduction in the direct band gap energy from 2.12 to 1.70 eV with the increase of annealing temperature was also found.