Wavelength-tunable linearly polarized luminescence film constructed using a highly efficient luminescent liquid crystal with stimuli-responsive property

Abstract

High-efficiency linearly polarized luminescence (LPL) materials are very important for display equipment and optical apparatus. Herein, we construct a free-standing film with a wavelength-tunable LPL property through the luminescent material. First, a highly efficient fluorescent reactive monomer (M6BP) based on α-cyanostilbene with stimuli-responsive behavior is successfully designed and synthesized. Then, the free-standing film is prepared by photo polymerizing the mixture of M6BP and liquid crystal (LC) monomer (C6M) in an antiparallel lab-made LC cell. The resultant film achieves a uniaxial orientation along the polyvinyl alcohol (PVA) substrate rubbing direction, which endows it with good LPL behavior. The dichroic ratio (N) and polarization ratio (ρ) values of the film are measured as 2.63 and 0.45, respectively. Owing to the existence of the pyridine group, the resultant film exhibits a reversible fluorescence switch with LPL property under trifluoroacetic acid (TFA)/triethylamine (TEA) vapors. Furthermore, a film with a special orientation pattern is obtained by photoalignment, and it is further successfully applied in the anti-counterfeiting field. This work provides a new method to fabricate optical devices with wavelength-tunable LPL property.