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PEDOT as an alignment layer and electrode in AFLC devices

Medialdea D. P., Bennis N., Cerrolaza B., Quintana X., Otón J. M., Arredondo B., Romero B., Geday M. A.

Opto-Electronics Review

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2009

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Vol. 17, No. 1

78-83

EN

PEDOT [Poly (3, 4-ethylenedioxythiophene) poly (styrenesulfonate)] is a material typically used organic light emission displays (OLEDs) manufactured as a conductor, or rather, as a hole injector. In this paper, three different issues have been studied: the use of rubbed PEDOT as alignment layer, the resistivity of the applied PEDOT layers, i.e., its potential as a replacement of ITO electrodes, and the induction of asymmetry in the electro-optical response of liquid crystal cells by assembling the display with dissimilar coated aligning surfaces - PEDOT on one side and buffed nylon on the counter electrode.

2

Nearly-analogue blazed phase grating using high birefringence liquid crystal

Bennis N., Geday M. A., Quintana X., Cerrolaza B., Medialdea D. P., Spadło A., Dąbrowski R., Otón J. M.

Opto-Electronics Review

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2009

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Vol. 17, No. 2

112-115

EN

Diffraction of liquid crystal gratings has been thoroughly studied for many applications such as diffraction optics, optical processing, and spectral analysis. In pure optical processing one varies the direction of propagation of light beam without any mechanical adjustment. In this work we propose a beam steering device using highly birefringent liquid crystal material. Using a highly birefringent material one can reduce the LC layer thickness needed to achieve 2 π of phase modulation and thus reduce the fringing effect caused by deformation of the electric field at the edge of the pixel. Here, we present 1.5-µm thick, high-resolution diffraction grating with non-detectable fringing.

3

Effect of bias in ferroelectric-antiferroelectric relaxation

Geday M. A., Medialdea D. P., Cerrolaza B., Bennis N., Quintana X., Otón J. M.

Opto-Electronics Review

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2009

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Vol. 17, No. 2

140-143

EN

The ferroelectric-antiferroelectric transition in greyscale generation of antiferroelectric liquid crystal displays (AFLC) is a heterogeneous process. The process has been described as the growth of finger-like domains [1]. We have previously studied the ferroelectric-antiferroelectric phase transition, relaxation that follows the data pulse in surface stabilized asymmetric antiferroelectric liquid crystal displays using biasless video frequency waveforms [2]. This relaxation involves an intensity decay of the light transmitted by a pixel and depends on several parameters such as surface stabilization, rotational viscosity of the AFLC, magnitude of the data pulse, and bias voltage. The usual multiplexed driving of AFLC displays leads to long-term stabilisation of the grey levels induced by the data pulses within the selection time. However, depending on the bias level, alternative greyscale mechanisms may be obtained by allowing the grey levels to decay during the frametime. These greyscales may be advantageous in some instances since they improve the dynamic response of the AFLC device and reduce the reset time of the waveform. In this study we extend the previous work to include the effect of bias. We present the measured data, in terms of growth pattern and speed and present an extension of the previously model on order to explain the results.