Circularly Polarized Luminescence Switching of Chiral Perylene Diimide‐Doped Nematic Liquid Crystal Using DC Electric Field

Abstract

AbstractTo obtain chiral luminescent nematic liquid crystals (N*‐LCs), two sets of chiral perylene luminescent materials (R,R)/(S,S)‐N,N′‐bis(1‐cyclohexylethyl)perylene‐3,4,9,10‐tetracarboxylic diimide [(R,R)/(S,S)‐CPDI] and (R,R)/(S,S)‐N,N′‐bis(1‐phenylethyl)perylene‐3,4,9,10‐tetracarboxylic diimide [(R,R)/(S,S)‐BPP] were prepared and doped into a nematic liquid crystal (N‐LC), 5CB. The obtained liquid crystals N*‐LC‐CPDI and N*‐LC‐BPP emitted stronger circularly polarized luminescence (CPL) signals than the CPDI‐ and BPP‐containing chiral poly(methyl methacrylate) (PMMA) luminescent films owing to higher helical twist power. When a direct current (DC) electric field was applied to N*‐LC, a reversible CPL response was obtained due to the field‐induced phase transition from the chiral nematic phase to the nematic phase. This demonstrated the successful construction of an ′′on‐off‐on′′ CPL system based on a DC electric field and was attributed to the change in the liquid crystalline organization from a uniformly lying helical structure to a planar one. This work can provide an effective strategy for the development of functional CPL devices in which the CPL can be regulated by applying a DC electric field to the N*‐LC.