In this paper, relationships between the scattering domain parameters (size and shape) and the light-shielding properties of thermotropic systems with fixed domains (TSFD) are established. Specific focus is given to the effect of additive type on the formation of scattering domain size. Various functional layers are prepared by a variation of thermotropic additives. Scattering domains are investigated applying high resolution Atomic Force Microscopy (AFM) in a phase imaging mode. Thermotropic layers formulated with additive types exhibiting a short chain length display roughly spherical scattering particles with dimensions between 0.5 and 3 µm and a moderate reduction in hemispheric solar transmittance along with a significant increase in diffuse solar transmittance above the switching threshold. Additive types with long-chain molecules develop anisotropic scattering domains resembling distorted disks with a diameter up to 50 µm and a thickness between 100 and 400 nm. Disk-like scattering features yield enhanced light-shielding properties. Copyright © 2009 John Wiley & Sons, Ltd.