Incorporation of Organic Compound into Silica Matrix by a Sol-Gel Process for NLO Applications

In this work, MNA (2-methyl-4-nitroaniline) and substituted carbazoles were incorporated into silica matrix to form composite thin films on the glass substrate by a sol-gel processing for NLO applications. In the composite thin films, the thermal stability was dependent on the type of functional groups incorporated into the organic compounds. Carbazole-2 (5-nitro-9-hydroxylethyl-carbazole) which has a terminal -OH group showed enhanced thermal stability, whereas carbazole-1 (5-nitro-9-ethyl-carbazole) and MNA, which do not have a reactive functional group, showed rapid degradation upon thermal treatment. This strongly suggests that the thermal stability of incorporated organic compounds can be enhanced by a reactive terminal group in organic compound without severely damaging the NLO property.