Molecular hybrid optical limiting materials from polyhedral oligomer silsequioxane: Preparation and relationship between molecular structure and properties

A series of new molecular hybrids with stilbene chromophore (H1-H4) are prepared by hydrosilylation of octahydridosilsesquioxane (T₈ ^H). AU these stilbene-containing hybrid materials are soluble in common organic solvents, such as chloroform, toluene, THF, and 1, 2-dichloroethane, and possess good film-forming properties. Their structures and properties are characterized and evaluated by FT-IR, NMR, UV, PL, TGA, DSC, nonlinear optical (NLO), and optical limiting (OL) analyses. The results show that the thermal decomposition temperatures (T_d, 5 mass % loss) of the hybrids are 20 - 60 °C greater than their corresponding stilbene monomers, and the hybrids show obvious nonlinear absorption (β up to 2.56 × 10^-11 m/W) and optical limiting properties. The larger excited-state absorption cross sections than corresponding ground-state absorption cross sections of the hybrids indicate that reverse saturable absorption is a major mechanism responsible for the optical limiting of the hybrids.