Light scattering materials for energy-related applications: Determination of absorption and scattering coefficients

To facilitate optical design of energy-efficient materials and devices, a detailed knowledge of their basic optical parameters is necessary. In this paper we present a novel method for determining scattering (S) and absorption (K) coefficients from total transmittance and reflectance measurements by inversion of the Kubelka-Munk theory. The reflectance parameters appearing in this theory depend on the angular distribution of scattered light inside the material. The versatility of our method is demonstrated by a reanalysis of experimental data for several materials of interest in energy-related applications. Specifically, we report spectra of S and K for: (a) pigmented polymer foils for radiative cooling applications; (b) suspended particle devices for smart windows; (c) solar reflecting TiO₂-pigmented paints and (d) selective solar absorbing paints for solar collectors.