Extinction coefficient modulation of moo₃ films doped with plasmonic nanoparticles: From an effective medium theory description

This work focused on the application of the effective medium theory to describe the extinction coefficient (Q_ext) 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 Q_ext of MoO₃. It was shown that the β-phase of MoO₃ enhanced the intensity response of the Q_ext 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 Q_ext. On the other hand, Cu nanoparticles with a radius of 20 nm embedded in MoO₃ was the configuration that presented intensities in Q_ext 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.