Zirconium phosphate phosphonate multilayered films based on push-pull stilbazolium salt: synthesis, characterization and second harmonic generation

The preparation of materials featuring enhanced second harmonic generation (SHG) values by self-assembly of molecules characterized by high second-order non-linear optic (NLO) activity is nowadays an important and challenging field of research. In order to show SHG the material must have an acentric structure with the dipoles of the molecular components oriented in the same direction and this is synthetically fairly difficult to achieve. This study describes the synthesis of the push–pull stilbazolium salt 1 and its assembly in multilayered acentric thin films, on quartz glass surface, by using the zirconium phosphate/phosphonate (Zr-POx) technique. A particular care has been paid to the optimization of the surface preparation and of the deposition conditions. This allows to obtain highly homogeneous lamellar inorganic–organic materials showing satisfactory second harmonic generation (SHG) values together with high chemical, thermal and mechanical stabilities which are necessary for their integration in optoelectronic devices.