Electrically modulated optical properties of fluorescent chiral nematic liquid crystals

摘要

Due to the superior optical properties and tremendous application prospects in the field of optical devices, both rare earth complex (REC) and chiral nematic liquid crystal (CNLC) have attracted widespread attention in the fields of theoretical research and engineering applications. Among the research on the optical behaviors of CNLC or REC, the controllable modulation of selective reflection of CNLCs and emitted fluorescence of RECs is of great significance to fabricated tunable optical materials. In this study, europium (III) complexes are dissolved and assembled in the chiral matrix of CNLCs to form binary CNLC-REC composites due to excellent compatibility between RECs and CNLCs. The selective reflection combined with the photoluminescence of binary fluorescent CNLCs are investigated, an electrically-controlled microscopic structure model is established to elaborate the dual-mode optical modulation based on the stable CNLC-REC composites. The reflectance of CNLCs can be tuned in the process from planar state with brilliant Bragg reflection to focal conic state with chaotic scattering, the intensity of fluorescence emitted by RECs can be modulated due to the increased scattering of incident UV light on the surface of CNLC-REC composite films. Furthermore, the dual-mode optical modulation can be operated at low voltages and the response time is within 3 ms. This facile and ultrafast methodology can be used to develop state-of-the-art tunable optical devices in the fields of LC display, fluorescent display and optical sensors.