A mathematical model is proposed for calculating the ionization potentials of molecules on the surface of dielectrics in order to quantify changes in the electronic characteristics of materials on a substrate. The semiconductor and photoelectronic properties of nanosystems based on phthalocyanine derivatives are determined by the electronic structure of molecules. Based on the zinc phthalocyaninate molecule ZnC32N8H16, model structures are constructed that increase this molecule by attaching benzene rings ZnC48N8H24, ZnC64N8H32 and a model simulating the film structure of Zn4C120N32 H48. Graphene was considered as a nanostructure modeling a fragment of a monomer lm. The ionization potentials of these compounds on the surface of magnesium oxide, sodium chloride and silicon are calculated. In the presence of a substrate, the ionization potentials of all nanostructures decrease, while the values of the surface ionization potentials remain fundamentally dierent in their magnitude for all compounds. The compound ZnC64N8H32 sprayed onto the surface exhibits the best photoelectronic properties, its surface ionization potential is comparable to graphene.