Adjustable active–passive dual-frequency liquid crystal smart window based on thermally responsive chiral molecules

https://doi.org/10.1016/j.molliq.2024.126383

We present a cholesteric liquid crystal (CLC) smart window with both passive and active control mechanisms, capable of reversible thermo-optical switching from high-transmission to low-transmission states as the temperature increases. By incorporating a mixture of a thermoresponsive chiral dopant and a left-handed chiral dopant into dual-frequency liquid crystal (DFLC), we have produced thermosensitive CLC that exhibit weak left-handed chirality at low temperature and enhanced left-handed chirality at rising temperature. This change in chirality strength results in increasing thickness-to-pitch ratio as the ambient temperature increases, transforming the CLC texture from the homeotropic to fingerprint state. Additionally, we doped a dichroic dye into the thermosensitive CLC to promote the contrast ratio between the high-transmission homeotropic and low-transmission fingerprint optical textures. Simultaneously, dielectric anisotropy in the host DFLC at different frequencies allows for adjustable switching temperature and varying transparency level. This advancement in smart window technology offers more control options and holds significant potential for practical applications.