Security use of bilayer dichroic films made of liquid crystal polymer networks

We report on bilayer dichroic dye-doped liquid crystal (BDLC) films for patternable color codes, which can be used in anti-counterfeiting applications such as security codes and, unlike the conventional single-layer LC color films, show unique color changes depending on the direction of the polarization of the incident light that passes through them. This is a facile way to enhance the security level of security codes. BDLC films are fabricated by laminating two single-layer LC polymer network films with crossed optical axes. We believe that BDLC films can be used as a new platform for a security-enhanced anti-counterfeiting code that can replace complex chiral materials or expensive plasmonic particles.