title: Octupolar molecules for nonlinear optics: from molecular design to crystals and films with large second-harmonic generation.
abstract: We summarize the nonlinear optical (NLO) properties of octupolar molecules, crystals, and films developed in our laboratory. We present the design strategy, structure-property relationship, and second-order NLO properties of 1,3,5-trinitro- and 1,3,5-tricyano-2,4,6-tris(p-diethylaminostyryl)benzene (TTB) derivatives, TTB crystals, and films prepared by free-casting TTB in poly(methyl methacrylate) (PMMA). The first hyperpolarizability of TTB was fivefold larger than that of the dipolar analogue. Moreover, the TTB crystal showed unprecedentedly large second-harmonic generation (SHG). While TTB crystal films (20 wt% TTB/PMMA) on various substrates showed appreciable SHG values, the cylinder film exhibited much larger SHG values and large electro-optic (EO) coefficients. The large SHG values and EO coefficients, as well as the high thermal stability of the cylinder film, will make it a potential candidate for NLO device applications.
authors.affiliation: Department of Physics and Research Institute of Natural Science, Gyeongsang National University, Jinju, 660-701, South Korea.
authors.forename: Mi-Yun
authors.initials: MY
authors.lastname: Jeong
authors.forename: Bong Rae
authors.initials: BR
authors.lastname: Cho
keywords: crystal growth; nonlinear optics; octupolar molecules; structure-activity relationships; thin films