Electrochromic Encryption and Decryption Smart Films Fabricated by Selective Photopolymerization of Polarization-Dependent Triphenylamine-Based Thin Films

The newly designed triphenylamine (TPA) based asymmetric monomer (TPA-A) is synthesized for the development of a high-security information encryption system. TPA-A exhibits photoluminescence (PL) emission and redox-active electrochromic (EC) properties, highlighting its potential as a smart encryptable ink. Introducing a methyl group to one side branch of the TPA-A induces a steric hindrance effect, enabling TPA-A to form a self-assembled lamello-columnar structure. This structural modification reduces the phase transition temperature and simultaneously allows for the uniaxial orientation of TPA-A by a simple shear-coating process. The uniaxially oriented and self-assembled TPA-A thin films exhibits polarization-dependent PL properties and electrofluorochromic (EFC) characteristics combined with redox-responsive EC properties. The selective photopolymerization of polarization-dependent TPA-A thin film generates a dual-mode information encryption system. The newly developed EC smart film can open a new door for optoelectronic information encryption and anti-counterfeiting technologies.