Spectral response and structural analyses of reactively sputtered molybdenum oxides for selective solar absorption

Molybdenum oxide (MoOx) film has attracted increasing research attention owing to its superior solar energy absorption. Herein, a series of monolayer MoOx films were fabricated on aluminium substrates through the reactive sputtering of single molybdenum targets. The reflectance spectra reveal that the spectral absorbance can be highly tuned by controlling the film thickness. Such monolayers exhibit high absorptivity and low emissivity of 0.83 and 0.05, respectively, at a partial pressure of 0.6 Pa, indicating their excellent selective absorption property. The scanning electron microscopy images show a morphological evolution from needle-like to spherical particles that may be responsible for the varying spectral absorption. In addition, X-ray diffraction and variable angle spectroscopic ellipsometry analyses confirm the films' semi-absorbing states. A MoOx/SiO2 solar absorber suggests that the resulting MoOx films have significant potential in solar energy harvesting.

Automated summary

A series of monolayer MoOx films were fabricated and it was found that the spectral absorbance can be highly tuned by controlling the film thickness. Under specific conditions, these monolayers exhibit high absorptivity and low emissivity, showing excellent selective absorption properties.