Fast Photoluminescence Switching in the Nematic Phase of Calamitic–Discotic Composites

Abstract

A photoluminescent (PL) system comprising a host calamitic–nematic and discotic fluorescent dopant is presented which can be switched at fast rates between two anisotropic values of photoluminescence using a two‐frequency addressing scheme. The employed unprecedented protocol, exhibiting the desirable higher contrast, switches two orders of magnitude faster than the standard mode of addressing. The methodology employed can be generalized and thus caters to a variety of fluorophores to cover the required PL wavelength. On the basis of X‐ray diffraction results it is demonstrated that as the discotic content is increased, the extent and nature of the short‐range order in the nematic phase changes, from that of a standard nematic to that of the locally columnar type. Imposing geometrical restrictions on this active system through a network of hydrogen‐bonded nanoparticles yields higher emission in both the field‐on and field‐off situations, although with a reduced anisotropy.

Anisotropic Fast Electrically Switchable Emission from Composites of CsPbBr3 Perovskite Quantum Cuboids in a Nematic Liquid Crystal

“…Hence, the Freedericksz mechanism can be exploited to reorient the LC molecules from the equilibrium planar (|| to the substrate) to the field‐driven homeotropic (⊥ to the substrate) configuration with E of f < f c and the return to equilibrium with E of f >> f c . This dual frequency protocol (DFP) is the basis for a variety of devices including switches, retarders, modulators, and displays . The point to be noted is that the dual frequency character exists for the CsLC composite also, although with a slightly higher f c value, and diminished ε a .…”

Synergistic Path for Dual Anisotropic and Electrically Switchable Emission From a Nanocomposite of CsPbBr3 Quantum Cuboids and Nematic Liquid Crystal

“…The molecular structure of the host calamitic LC compound, 4-pentylphenyl 2-chloro-4-(4-pentyl benzyloxy) benzoate or PCPBB for short, exhibits the nematic phase over a wide-range of temperatures through room temperature and has been used specifically for its dual frequency dielectric feature [12,13]. The composite, hereafter referred to as CsLC mixture, containing 2 wt% of CsPbBr3 in PCPBB, was prepared using the standard solution-mixing procedure followed by sonication and high-temperature treatment; toluene was used as the solvent for this purpose.…”