Jung Y. Huang, Liu S. Li and Ming C. Chen jyhuang.idv.tw/

1. Molecular Binding Effect from a Doping of ZnO Nanocrystals in Surface Stabilized Ferroelectric Liquid Crystal Jung Y. Huang, Liu S. Li and Ming C. Chen http://www.jyhuang.idv.tw/ We acknowledge the financial support from the National Science Council of the Republic of China under grant NSC 95-2112-M-009-031 and Taiwan TFTLCD Association Foundation No A623TT4000-V14.

2. Motivation • Liquid crystal materials with appropriate optical, visco-elastic hydrodynamic properties, and wide temperature range of the mesophase are needed for industrial applications . Previously, this stringent demand on LC material is achieved via eutectic mixture of LC species. • Develop a simple nonsynthetic method to tailor LC properties by doping various nanomaterials into LC. This approach may open up an effective and flexible way to yield promising new LC materials from existing LC compounds.

3. Time-resolved FTIR for the Field-Induced Switching of SSFLC

4. FLC nc-ZnO doped FLC The ZnO nanocrystals were dispersed uniformly into SSFLC. The homogeneous dispersion of nanocrystals leads to stronger correlation among the IR active modes of the FLC cores and among alkyl chains in the doped SSFLC film. Synchronous IR Correlation Plot: reveal uniaxial alignment

5. Asynchronous IR Correlation Plot: Revelation of angular deviation nc-ZnO doped FLC FLC

6. Doping SSFLC with ZnO nanocrystals results in more concerted orientational switching of sub molecular segments.

7. Response Times of Sub Molecular Segments of FLC to an Applied Electric Field

8. Preisach model of ferroelectric film

9. Preisach model of ferroelectric film • The doping-induced effect simplifies the CV characteristics of the FLC cells.

10. Optical Transmittance Patterns of SSFLC Cells The doping-induced effect also yields a factor of 2.5 improvement in the optical transmittance of the nc-ZnO-doped SSFLC cell.

11. The C=O group in the nc-ZnO doped SSFLC reacts more rapidly to an applied field can be explained in terms of an increased coupling strength of ξ=1.4. • At one weight percent of nc-ZnO in FLC used for this study, it corresponds to one nc-ZnO surrounded by 14800 FLC molecules in a volume of 1.110-17 cm3. • The dipolar interaction of a ZnO nano dot with surrounding C=O groups of FLC molecules is required to be effective within a sphere of 11-nm radius

12. Conclusions • Doping SSFLC with ZnO nanocrystals results in more ordered structure and yields more concerted orientational switching of sub molecular segments. • We proposed the observed molecular binding effect to originate from the dipole interaction of a ZnO nano dot with surrounding C=O groups of FLC molecules, which causes the C=O groups to react more rapidly to an applied field. • The doping method with semiconductor nano crystals may open up an effective way to yield promising new FLC materials from existing FLC compounds.