Electrowetting Display Units Based On Metallic Nanowire Grating

The display devices based on electrowetting technology has the advantage of lower power consumption compared with the liquid crystal displays(LCDs), also it has faster response time for video display compared with electronic books based on electrophoresis technology. In the very recent, there are much research about electrowetting displays owing to its great potential as a new kind of commercial display. This article introduces the research status and concept of electrowetting display technology including principle, structure and characteristic. The lost of backlight brightness is inescapable in the colorized display devices based on electrowetting technology due to the color ink absorption, although the performance of the display devices had been improved. Meantime the contrast of reflective display devices is not high due to the using of ink, and the dark display mode of the transmissive display devices needs complex three-layers structure. We put forward a novel prototype of transmissive electrowetting display units based metallic nanowire gratings that can realize the color adjustable without ink in order to solve these problems.An electrowetting display unit that can realize the change of transmissive gray by changing ambient refractive index based on bi-layer metallic nanowire gratings(BMNGs) is designed, attributed to the unique surface plasmon resonance and sensitive to the ambient refractive index: The surface plasmon resonance formula is used to determine the corresponding to grating period of different colors; The rigorous couple wave analysis(RCWA) method is used to optimize and design the reasonable grating duty ratio, metal thickness and the height of the grating. We design a novel prototype of transmissive electrowetting display by applying the optimized BMNG and realize the red color transmission. Peaked wavelength of 700 nm and transmittance of 50% under air ambient were obtained based on a BMNG with pitch of 650 nm, height of 100 nm and metal thickness of 40 nm. With the ambient materials changed from air to aqueous solution, the switching from bright red color state to dark state was fulfilled. The change of gray scale was proved. Different metal grating structures under air ambient and aqueous solution that can realize the blue color and green color transmission are also designed.This article firstly proposed the electrowetting display units based on BMNG, the device structure with high transmittance, green environmental protection and simple structure. This study will contribute to the novel electrowetting display devices with thinner compact structure, lower power consumption and higher resolution.