Grating formation time of photorefractive liquid crystal cell with mixed layer of PVK and p-PMEH-PPV

Abstract

The speed of photorefractive (PR) grating formation is determined by various processes such as the photogeneration of charge carriers, their subsequent migration by diffusion or drift in an electric field, transport of charge carriers, and reorientation of liquid crystals (LCs) by an internal space-charge field. Among them, the transport speed of charge carriers can be improved using pi-conjugated polymers. Thus, we prepared a layer-structured LC cell in which poly[o(p)-phenylenevinylene-alt-2methoxy-5-(2-ethylhexyloxy)-p-phenylenevinylene] (p-PMEH-PPV) was added to poly(9-vinylcarbazole) (PVK) at an appropriate ratio. Although sample cells showed slightly decreased PR effects due to the reduction of charge density and the number of trap sites, they showed an improved grating formation time required for a real-time hologram device.