Abstract :
[en] Materials with broadband tunable optical properties are looked for in smart
windows applications. Doped metal oxides presenting dual band visible (VIS)
near infrared (NIR) electrochromic properties can be used for solving such a
challenge, and their accurate optical characterization is therefore of prime
importance. Kubelka Munk model is a state of the art way to optically quantify
the absorption properties of materials and is occasionally applied to plasmonic
materials, even if great care should be taken to meet the formalism hypotheses.
In the present work, Kubelka Munk theory is discussed in the context of
particles of indium tin oxide and molybdenum tungsten oxide formulations that
are used as single NIR and both VIS and NIR active advanced electrochromic
materials, respectively. An analytical model is derived for particles of much
smaller dimensions than the incident wavelength and is experimentally verified.
A dilution method is applied to verify the plasmonic characteristics of the
particles. This study is key for efficient characterization of optical
properties of metal oxides, and plasmonic materials in general, from diffuse
reflectance measurements.
