Self-assembled chromophoric thin film NLO materials. Effect of coupling agent surface functionalization and ion exchange processes on second harmonic generation characteristics

• Published in: Thin solid films 1994-04, Vol.242 (1), p.142-145
• Main Authors: Kakkar, Ashok K., Yitzchaik, Shlomo, Roscoe, Stephen B., Marks, Tobin J., Lin, Weiping, Wong, George K.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Exact sciences and technology; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Physics; Polymers; organic compounds
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/0040-6090(94)90518-5

A systematic study of the reaction of 1-chloromethyl-4-(2-trichlorosilylethyl)-benzene (coupling agent) with the surface SiOH groups of glass for times from 15 min to 48 h, followed by stilbazole chromophore precursor deposition/quaternization, is reported. Second harmonic generation characteristics of these thin film materials indicate that a 15 min coupling agent reaction attains approximately 65% of full surface coverage (based on χ zzz (2)) of benzylic chloride moieties, but that 24 h is the optimal time for maximum coverage. The surface-anchored chromophoric chloride salts in such materials undergo facile ion exchange with iodide, p-aminobenzenesulphonate, and ethyl orange, leading to enhancements in χ zzz (2) of up to 50%.