DISPLAY
The main objective of the DISPLAY project is the development of a proof of concept of two demonstrators of a new energy-saving LCD technology that is based on the ultra-low elasticity recently discovered with bent-shaped liquid-crystalline compounds.
Context
Information and communication technologies play a crucial role in modern society. To satisfy the needs of both the professional and personal spheres, constantly increasing volumes of data are collected, treated, and finally delivered to the end-user, preferably as visual information. For this last step, display devices with high resolution and fast response times are required. Liquid crystal displays (LCD) have been particularly successful in addressing this hundred-billion-euro market. The early Passive Matrix (PM) multiplexed devices, after dramatic technological improvements, led to the modern Active Matrix (AM) megapixel LCD that occupy nowadays more than 90% of the display market.
Objectives
The objectives of this project are motivated by two main reasons:
The first one is the major advance in LC fundamental research that consists in the prediction and experimental discovery of the NTB phase. This spontaneously distorted phase arises from the anomalous bend elasticity of the nematic phases formed by strongly bent molecules. The same elastic anomaly drastically affects the physical properties in the usual nematic phase preceding the N-NTB transition. The most striking change is the large decrease of K33, by typically 1-2 orders of magnitude, in a large temperature range (up to 30-40 °C) above the N-NTB transition. Many other properties (e.g. birefringence and dielectric tensor) also show atypical behavior in this temperature range due to pretransitional fluctuations. This behavior disturbs the balance between the electric, elastic, and surface-alignment torques and leads to electric-field effects qualitatively different from the ones observed with classical compounds.
The second one is that these new properties of the usual nematic phase of bent-shaped compounds provide wide opportunities for new practical applications. In fact, the omnipresent LCD exploit electrooptic effects optimized with chiralized classic rod-like nematics. However, many other applications require much lower energy consumption. New LC displays, using the ultra-low K33 nematics with bent-shaped molecules, can address this market segment (the significance of which is evaluated in Part III). These LECLCD, operating in unpolarized light and bistable or quasi-bistable mode, may successfully compete with the e-Ink technology, which dominates today the e-reader market. Even more importantly for other applications, like smart windows, the new LEC-LC technology will be without competitors.
