Thermal Stability and Structural Characterization of Organic/Inorganic Hybrid Nonlinear Optical Material Containing a Two-Dimensional Chromophore

In this study, two nonlinear optic hybrid materials with different dimensional alkoxysilane dyes were prepared and characterized. One NLO silane (Cz2PhSO₂OH- TES), a two-dimensional structure based on carbazole, had a larger rotational volume than the other (DR19-TES). Second harmonic (d₃₃) analysis verified there is an optimum heating process for the best poling efficiency. The maximum d₃₃ value of NLO hybrid film containing Cz2PhSO₂OH was obtained for 10.7 pm/V after precuring at 150 °C for 3 h and poling at 210 °C for 60 min. The solid-state ²⁹Si NMR spectrum shows that the main factor influencing poling efficiency and thermal stability was cross-linking degree of NLO silane, but not that of TMOS. In particular, the two-dimensional sol−gel system has a greater dynamic and temporary stability than the one-dimensional system due to Cz2PhSO₂OH-TES requiring a larger volume to rotate in the hybrid matrix after cross-linking.