Broadband Chiroptics with Twist-stacked Hyperbolic Conducting Polymer Thin Films

Chiral-specific interaction of light with organic materials is important but typically arises from circular polarization-dependent absorption of specific optical transitions, resulting in narrow effective wavelength ranges. This study presents a scalable and universal concept for broadband circular dichroism (CD) enabled by strained conducting polymer thin films that possess in-plane hyperbolic optical behavior (i.e., optically metallic and dielectric properties along orthogonal directions). It is shown that off-axis stacking of two or more such thin films provides broadband CD that varies with the hyperbolic bandwidth and stacking geometry. By contrast to traditional chiroptical materials, the CD can also be modulated by redox-tuning of the hyperbolic polymer properties, opening for broadband dynamic chiroptical components.