Extinction Coefficient Modulation of MoO3 Films Doped with Plasmonic Nanoparticles: From an Effective Medium Theory Description

Abstract

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 β-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.

Effective medium theory and its limitations for the description of MoO3 films doped with nanoparticles

“…Previous simulations of transmittance at normal incidence have been conducted by our group [13,14]. But so far, it has not been identified if the optical transmittance changes as a function of the angle of incidence.…”

“…In this sense, it has been shown in recent works that molybdenum trioxide (MoO 3 ) doped with resonant NPs, such as gold (Au) or silver (Ag) shows very interesting * Authors to whom any correspondence should be addressed. and important changes in the transmittance and extinction coefficients [13,14]. But it is important to highlight here that for any applications that were mentioned before is necessary to focus on the analysis of the transmittance or absorbance coefficients as a function of oblique incidence of light.…”

α-MoO3 Microflakes Decorated with Gold Nanoislands as SERS-Active Substrates

“…These hybrid structures show a combined effect of both EM and CM enhancements in addition to better absorption of analytes over the SERS substrate. Generally, hybrid structures are prepared by depositing metal nanostructures over a metal oxide surface through various processes such as in situ growth, ex situ method, sol–gel, etc. − …”