  Vanadium dioxide (VO2) is an adjustable refractive index material and has
capability of behaving as semiconductor or conductor depending on its
temperature. Such condition makes it as a material which can be employed in
fabricating thermochromic smart windows. The transmission characteristics of
these type of windows strongly depend on the thickness of the film. Therefore,
some calculations are required to optimize the VO2 thickness. Unfortunately,
refractive index of VO2 thin film is thickness dependent, therefore, in
calculating the transmission of light spectrum from VO2 thin films, a unique
refractive index cannot be utilized. In the present paper using three
theoretical models (Lorentz-Drude oscillator, Lorentz oscillator, and
Tauc-Lorentz) and employing experimental results from previous reports, we
provide a collection of thickness dependent refractive index of VO2 films. More
precise transmission can be achieved by using this set of refractive index data
in the calculations which agree with those of experiments. These results also
fairly make us capable to determine optimized film thickness for any desired
transmission performance. This method is useful for design of VO2 based
thermochromic smart windows.
