Beneficial effect of heating on the morphology and second-order nonlinear optical efficiency of anisotropic thin films

In this Letter we describe the effect of heating on the quality, morphology and nonlinear optical efficiency of anisotropic Langmuir–Blodgett films composed of a chiral helicenebisquinone derivative. The samples were studied with second harmonic generation (SHG), UV–Vis absorption spectroscopy and atomic force microscopy (AFM). Heating a Langmuir–Blodgett film of a helicenebisquinone derivative improves the film quality (homogeneity, surface smoothness). In addition, it increases the filmʹs anisotropy and, as a consequence doubles its nonlinear optical efficiency.