Abstract
In this work, we study the inclusion mechanism of Fe
3+
ions in a polyvinyl alcohol (PVA) matrix. Thin films of pure and FeCl
3
-doped PVA on silicon substrates, prepared by the spin-coating method, are investigated using spectroscopic ellipsometry (SE) and Fourier transform infrared (FT-IR) spectroscopy. SE measurements of PVA and Fe
3+
-doped thin films are carried out at an incidence angle of 75° over the wavelength range of 0.24–1.1 μm. An optical model is used to obtain the refractive index (
n
) and the extinction coefficient (
k
). The gap energy
E
g
is afterwards evaluated. The Fe
3+
doping is found to affect strongly the optical parameters of the polymer films. In fact, an increase in the refractive index with doping is observed, resulting from the intermolecular hydrogen bonding between Fe
3+
ions with the adjacent OH group of PVA. The increase of the thin films' absorption with doping is estimated by the
k
spectral profile analysis. The gap energy is then calculated and shows an important decrease with the Fe
3+
filling, more pronounced for low doped samples. Such a behavior is confirmed by FT-IR analysis.