Mathematical modeling of spectral selective absorption and reflection of light by metal-dielectric composites

Abstract

Metal-dielectric absorbing composite coatings are widely used in solar cell elements, as ‘black’ coatings in optical instruments. An approach to theoretical evaluation of spectral dependent absorption and Fresnel reflection coefficients for a concentrated system of absorbing spherical metal particles imbedded in a dielectric matrix is presented. The approach is based on the renormalized cluster expansion for the dielectric function of a disordered system of strongly absorbing dipole scatterers. Dipole—dipole interaction depending on the particle concentration are taken into account. The calculation procedure predicts optical behavior of particulate metal composite coatings on glass. As an example of the use of the method calculated spectra of the absorption and Fresnel reflection coefficients for silver and copper particle systems in a transparent dielectric matrix are presented. Changes of the position, the intensity and the shape of optical absorption spectral bands due to concentration effects and formation of shells around metal particles are discussed.