Fluorescent photochromic molecules that exhibit distinct light‐triggered changes in their emission colors are highly desirable for the fabrication of smart soft materials and advanced photonic devices. α‐Cyanodiarylethenes, that is, α‐cyano‐functionalized diarylethenes, as alternative “non‐azo” Z/E photochromic molecular switches, are popular choices due to their unique characteristics such as their aggregation‐induced emission or aggregation‐induced‐enhanced emission behavior in their self‐assembled states, and visible changes in fluorescence colors during Z/E photoisomerization. In recent years, the development of fluorescent photochromic α‐cyanodiarylethene‐based compounds including α‐cyanostilbenes, dicyanodistyrylbenzenes, and diaryldicyanoethenes, has mainly focused on molecular design, photochemical and photophysical behavior in solution, and smart soft matter technologies. In this review, recent significant achievements in light‐responsive systems based on the Z/E photoisomerization of fluorescent photochromic α‐cyanodiarylethene switches that span the range from liquid crystals to gels and finally to self‐assembled nanostructures, are highlighted. The smart soft materials constructed from α‐cyanodiarylethene molecular switches find use in a plethora of areas, including display, sensing, encrypting, actuating, and biomedical imaging applications, among others. The review concludes with a brief perspective on some major challenges and opportunities for the future development of light‐responsive smart soft photonic materials.

Circularly polarized luminescence (CPL) has gained considerable attention in various systems and has rapidly developed into an emerging research field. To meet the needs of actual applications in diverse fields, a high luminescence dissymmetry factor (g lum ) and tunable optical performance of CPL would be the most urgent pursuit for researchers. Accordingly, many emerging CPL materials and various strategies have been developed to address these critical issues. Emissive cholesteric liquid crystals (CLCs), that is, luminescent self-organized helical superstructures, are considered to be ideal candidates for constructing CPL-active materials, as they not only exhibit high g lum values, but also enable flexible optical control of CPL. This review mainly summarizes the characteristics of CPL based on CLCs as the bulk phase doped with different emitters, including aggregated induced emission molecules, conventional organic small molecules, polymer emitters, metal-organic complex emitters, and luminescent nanoparticles. In addition, the recent significant progress in stimulus-responsive CPL based on emissive CLCs in terms of several types of stimuli, including light, electricity, temperature, mechanical force, and multiple stimuli is presented. Finally, a short perspective on the opportunities and challenges associated with CPL-active materials based on the CLC field is provided. This review is anticipated to offer new insights and guidelines for developing CLC-based CPL-active materials for broader applications.

Reported here is the first example of a 1,2‐dithienyldicyanoethene‐based visible‐light‐driven chiral fluorescent molecular switch that exhibits reversible trans to cis photoisomerization. The trans form in solution almost completely transforms into the cis form, accompanied by a 10‐fold decrease in its fluorescence intensity within 60 seconds when exposed to green light (520 nm). The reverse isomerization proceeds upon irradiation with blue light (405 nm). When doped into commercially available achiral liquid crystal hosts, this molecular switch efficiently induces luminescent helical superstructures, that is, a cholesteric phase. The intensity of the circularly polarized fluorescence as well as the selective reflection wavelength of the induced cholesteric phases can be reversibly tuned using visible light of two different wavelengths. Optically rewritable photonic devices using cholesteric films containing this molecular switch are described.

Stimuli‐triggered changes in the emission color of functional materials are in demand for a variety of potential applications. Herein, a strategy to reversibly phototune fluorescence color in cholesteric liquid crystal (CLC) with self‐organized luminescent helical superstructure via fluorescence resonance energy transfer (FRET) is developed. This dynamic FRET system is constructed by doping with 1,2‐dithienyldicyanoethene‐based chiral fluorescent photoswitch (switch 7) as an acceptor and a conventional coumarin dye C6 as a donor into a nematic liquid crystal (LC) host. The efficient energy transfer from C6 to switch 7 in the LC media, which is evidenced by both of emission color shift and enhanced circularly polarized luminescence, can be modulated on the basis of reversible trans–cis photoisomerization of switch 7 upon visible/UV light irradiations, leading to the emission color change from orange to green. Noteworthily, the FRET efficiency can be significantly improved when CLCs are confined in the polymer microtubes. Preliminary demonstrations of the LC film and LC microtubes array for information display and encryption with ease of electrical operation between planar, homeotropic, and focal conic states or light manipulation are described.

Materials with phototunable full-color circularly polarized luminescence (CPL) have a large storage density, high-security level, and enormous prospects in the field of information encryption and decryption. In this work, device-friendly solid films with color tunability are prepared by constructing Förster resonance energy transfer (FRET) platforms with chiral donors and achiral molecular switches in liquid crystal photonic capsules (LCPCs). These LCPCs exhibit photoswitchable CPL from initial blue emission to RGB trichromatic signals under UV irradiation due to the synergistic effect of energy and chirality transfer and show strong time dependence because of the different FRET efficiencies at each time node. Based on these phototunable CPL and time response characteristics, the concept of multilevel data encryption by using LCPC films is demonstrated.