A flexible reverse-mode liquid crystal/polymer composite film with low driving voltage and high stability for energy-efficient smart windows

Smart windows are attractive considering their contribution to energy efficiency and privacy protection. However, the achievement of flexible reverse-mode film with good stability and well electro-optical performance for smart windows remains a fascinating challenge in recent years. Herein, we reported a low-driving-voltage, high-stability flexible reverse-mode liquid crystal/polymer composite film for energy-efficient smart windows by the formation of polymer structure with a polyhedral oligomeric silsesquioxane (POSS) core and strong epoxy resin as chains. The experimental results suggested that the polymer can not only stabilise the planar state of the cholesteric liquid crystal in the zero field but also provide enough support to the continuous liquid crystal phase on flexible substrate. Besides, the optimised optical device could be fully driven at 30 V (lower than safety voltage, 36 V) and keep contrast ratio of 100. Moreover, the flexible film showed outstanding optical regulation performance and excellent cycle stability under electric field. The strategy used in this research would open new doors for the development of energy-efficient smart windows in buildings.