Spectral ellipsometry study in the range of electronic excitations and band structure of [(CH3)2CHNH3]4Cd3Cl10 crystals

► Spectral ellipsometry in the VUV range is used for study of (IPA)4Cd3Cl10 crystals. ► Band structure of (IPA)4Cd3Cl10 crystal has been calculated for the first time. ► Origin of the lowest energy spectral band of dielectric function is determined. ► Width of temperature dependency of dielectric permittivity is large (near 50 K). ► Maximum of temperature dependency of dielectric permittivity is small (near 2%).