Observation of Electrical Write/Erase Operations for a Memory-Type Polymer-Dispersed Cholesteric Liquid Crystal

A polymer-dispersed cholesteric (chiral nematic) liquid crystal (PDCLC) with a memory effect is effective for color display devices. The PDCLC stably maintains both selectively reflective and transparent states without holding techniques, and the states can be changed electrically. A high-frequency electric field writes to the reflective state, and a low-frequency field erases to the transparent state. To understand the details of transition between the states, we observed the intensity of light transmitted through a PDCLC cell during operation using a digital oscilloscope. Furthermore, the frequency-dependent current in the PDCLC cell was also measured to evaluate ion movement. The results show that ion movement in the PDCLC layer plays an important role in the electrical erase operation.