The Effect of Chromophore Architecture and Deposition Conditions on the Optical and Microstructural Characteristics of Self-Assembled Chromophoric Thin Film NLO Materials

Abstract

Construction on inorganic oxide substrates of covalently self-assembled second-order nonlinear optical (NLO) materials containing a variety of acentrically organized high-β 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 chromophorc 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 X ⁽²⁾ _zzz for ∼ 25 Å thick monolayers of up to 7 × 10⁻⁷ esu at 1064 nm.