The article deals with the investigation of concentration dependences of absorption, luminescence and photosensitivity impurity bands, caused by the introduction of overstoichiometric cadmium atoms (Cdi) into the lattice of strongly anisotropic CdI2layered crystal. The model, explaining concentration dependences of CdI2-Cdispectra, suggests localization of Cdiatoms in Van-der-Waals gaps of layered crystals and their interaction with themselves and with lattice iodine atoms. The character of these interactions strongly depends on Cdi, concentration (i.e. on the distance between Cdiatoms) and changes froms-Cdi-p-I (at NCdi< 10<sp>18 cm−3) tos-Cdi-s-Cdiinteraction at higher concentration. The quantum-chemical simulations were carried out to confirm the proposed model.