Construction on inorganic oxide substrates of covalently self-assembled second-order nonlinear optical (NLO) materials containing a variety of acentrically organized high-Yβ chromophores is investigated as a function of film deposition conditions. Structurally different chromophores exhibit varying packing arrangements on the surface. Changing the medium for the chromophore deposition reaction on functionalized surfaces from a polar solvent to a nonpolar solvent and raising the temperature increases the chromophore number density on the surface and yields improved NLO response. These robust thin film materials show very high second harmonic generation (SHG) efficiencies with for ~ 25 À thick monolayers of up to 7 x 10-7 esu at 1064 nm.
Bibliographical noteFunding Information:
Materials Research Center of Northwestern University (Grant DMR9120521) and by the Air Force Office of Scientific Research (Contract 90-0071). A.K.K. thanks NSERC of Canada for a post-doctoral fellowship.