RESUMO
The present work analyses the transmittance and reflectance spectra of molybdenum trioxide film doped by silver nanoparticles as a function of angle of incidence and wavelength. As will be seen in this work, at values of angle of incidence below 40 degrees and with volume filling fraction below 1% also, some differences between the two effective medium theories are presented. First, the volume filling fraction is limited for low values (<1%) and second the scattering amplitude cannot be ignored for these cases. The novelty of this work is that the use of the effective medium model (refractive index) shows limitations in the description of the optical properties when it was applied to thin solid films.
RESUMO
This work focused on the application of the effective medium theory to describe the extinction coefficient (Qext) in molybdenum trioxide (MoO3) doped with different kinds of plasmonic nanoparticles, such as silver (Ag), gold (Au), and copper (Cu). Usually, in studies of these materials, it is normal to analyze the transmission or absorption spectra. However, the effect of this type or size of nanoparticles on the spectra is not as remarkable as the effect that is found by analyzing the Qext of MoO3. It was shown that the ß-phase of MoO3 enhanced the intensity response of the Qext when compared to the α-phase of MoO3. With a nanoparticle size of 5 nm, the Ag-doped MoO3 was the configuration that presents the best response in Qext. On the other hand, Cu nanoparticles with a radius of 20 nm embedded in MoO3 was the configuration that presented intensities in Qext similar to the cases of Au and Ag nanoparticles. Therefore, implementing the effective medium theory can serve as a guide for experimental researchers for the application of these materials as an absorbing layer in photovoltaic cells.