The molecular orientation at the surface of polyimide (PI) alignment layers used for liquid crystal displays has been determined using X-ray absorption spectroscopy (NEXAFS). The second moments of the orientation distribution function obtained from a detailed analysis reveal that, upon rubbing, the PI substrates develop biaxiality and an inclination of a few degrees. For a nematic liquid crystal (LC) in contact with these alignment layers, the pretilt angle was determined and revealed a weak correlation with buffing strength.

Rotational viscosity and spontaneous polarization are the most important properties of a ferroelectric liquid crystal with regard to its switching time in surface stabilized or a x . field stabilized displays. Whereas there is an abundant literature about spontaneous polarization, only a few attempts have been made to determine the rotational viscosity. We set up a model for the electric response of a ferroelectric liquid crystal cell on application of an electric field. For the application of a triangular wave voltage we derive a relation between the rotational viscosity, the spontaneous polarization, the tilt angle, the maximum induced polarization current and the electric field strength. Experiments are carried out on several ferroelectric liquid crystals and the derived relation was used to determine the rotational viscosity. The relation between the rotational viscosity and the polarization on the one hand and the optical switching time o n the other hand is discussed in some detail.

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We report performance of red, green and blue inkjet printed organic light emitting diodes with common blue device architecture. Device efficiency, voltage, color and lifetime are reported, and emission profile discussed. We demonstrate that inkjet printed OLED performance metrics are rapidly approaching commercial requirements for display applications, and discuss strong potential for further progress.