P‐12.9: Dye‐Doped Nematic Liquid Crystal for Smart Windows

Abstract

Dye‐doped nematic liquid crystal mixtures (DNLC) were prepared by mixing positive dichroic dye into our novel designed negative liquid crystals. Furthermore, the optical transmittance of their devices was investigated, with the concentration increasing of dichroic dye from 0.8wt% to 6.5wt%, the transmittance of both ON/OFF states decreases simultaneously and the contrast ratio goes up from 1.5 to 8.5 gradually. It is noted that when the dichroic dye is used at the concentration of 4.5wt% in DNLC, the dimming range is able to reach a high value up to 46.6%. Besides, owning to the low flow viscosity design of DNLC mixture, the devices are possible to be prepared easily by ODF process. For dimmer application, the low energy consumption is important and attractive, the DNLC with high dielectric constant makes the devices work at low voltage, the usable dimming can be driven even from 4V, besides the devices present low haze level. Moreover, the DNLC devices have fast response time under 200ms, and good low temperature storage properties at ‐ 40°C for 240hr. It is worth emphasizing here, there are two points of technology innovation for our reported DNLC devices. One is that the dimming range have an increase to 46.6% in comparison with 35−40% of our previous results. The other is that reliabilities are promoted because of the novel‐designed DNLC mixture. We expect our DNLC as smart windows could be applied in high‐speed train, automobile, airplane, buildings and so on in the close future widely.