Octupolar films with significant second-harmonic generation

The structural and optical properties of 1,3,5-tricyano-2,4,6-tris(p- diethylaminostyryl)benzene/polymethylmethacrylate (TTB/PMMA) films were prepared by depositing a solution of TTB and PMMA in chlorobenzene on cleaned glass plates (BK7) of 1 mm thickness by using freecasting and spin-coating methods. The existence of crystalline domains in the free-cast film was demonstrated by X-ray diffraction (XRD) spectra. An incoming beam at 1064 nm (or 1560 nm) of linear polarization was used to illuminate a crystal domain in the free-cast film along the Z direction, while rotating the polarization angle, to determine the domain structure by using SHG polarized responses. It was observed that free-cast films have crystal domains that have hexagonal columnar structure and show significant SHG and high thermal stability.