Circularly polarized light-responsive device based on supramolecular chiral-assembly of conjugated polymers

Abstract

A security-enhanced chiroptical device can be fabricated using a ferroelectric helical nanostructure capable of circularly polarized light. In particular, this is important as it can further increase the cryptographic properties when generating a digitized key for encryption. Furthermore, it can be applied as a ferroelectric memory device that requires high security, such as an IC card or RFID tag. However, the formation of ferroelectric helical nanostructures is a great challenge. Herein, we report facile and effective fabrication of hierarchical helical nanowires composed of conjugated polymers and ferroelectric polymers through crystallization -driven self-assembly. The pre-assembled P3HT-b-PMMA helical nanowires were achieved by inducing chirality transfer through the addition of limonene as a chiral trigger. The hydrogen bonding and dipole-dipole interaction between the PMMA and P(VDF-TrFE) are significant in extending the chirality of the pre-assembled helical nanowires to the hierarchical structures. The amplified chirality through the sergeant-soldier effect was confirmed through circular dichroism spectroscopy measurement. Helical nanostructured films showed retained optical activity, indicating the applicability of chiroptical devices. As a proof of concept for advanced applications for security enhancement, CPL-responsive devices are demonstrated as physically unclonable function (PUF) devices for ferroelectric cryptographic authentication. When the CPL is encoded into the digitized key creation in this system, the number of possible choices can be expanded. These improved cryptographic properties could be useful in a variety of security and ferroelectric memory device applications.