Ferroelectricity of a hemicyanine dye in ultrathin organized molecular films: hysteresis and pyroelectric effects

Pyroelectricity of the optical nonlinear hemicyanine dye in organized molec ular films has been demonstrated by using the electric polarization and sec ond harmonic generation measurements. The typical hysteresis loop of the sa mples confirmed existence of the remnant polarization of hemicyanine molecu les which is 600 mu C m(-2). The pyroelectric coefficient of hemicyanine wa s found to be 12 mu C m(-2) K-1 at room temperature and enhanced with incre asing temperature monotonically which was well explained by using a molecul ar dipole reorientation model. (C) 1999 American Institute of Physics. [S00 03-6951(99)01714-3].