High-Quality Organic Single Crystalline Thin Films for Nonlinear Optical Applications by Vapor Growth

We report on the production of organic single crystalline thin films for integrated nonlinear optical applications by a vapor growth technique. The configurationally locked polyene chromophore 2-{3-[2-(4-dimethylaminophenyl)vinyl]-5,5-dimethylcyclohex-2-enylidene} malononitrile (DAT2) that was used exhibits a noncentrosymmetric crystalline arrangement with monoclinic point group symmetry 2. It shows a second harmonic generation signal of about 2 orders of magnitude greater than that of urea. The grown DAT2 films are single crystalline and exhibit good optical quality and suitable size (area of ∼5 × 3 mm2 and the thickness in the range of 0.2−5 μm) for fabrication of photonic devices. Growth rates of a few hours have been achieved. Furthermore, the edges of the films are sharp and flat, which greatly reduces the additional processing requirements for applications.