Giant Ultraviolet Circular Dichroism in Macroscopic Carbon Nanotube Architectures with Engineered Chirality

Controlling the dissymmetric interaction of circularly polarized light with solid-state materials is required for chiral quantum photonic systems. The extraordinarily strong 1D quantum confinement of electrons and photons in carbon nanotubes (CNTs) leads to robust quantum phenomena, ideally suited for developing high-operating-temperature devices to generate, modulate, and detect quantum light. There have been no reports on macroscopic assemblies of ordered CNTs with chiroptical properties. We have studied the response of films of aligned racemic CNTs, prepared by controlled vacuum filtration (CVF), and their ordered 3D architectures. First, we observed the largest deep-UV optical rotatory power ever reported for a wafer-scale chiral assembly of CNTs, with pronounced circular dichroism signals (50 mdeg/nm). Scanning electron microscopy revealed a rotation of alignment directors between layers in aligned CNT films. This spontaneously formed twisted stack of aligned CNT thin layers during CVF led to a structure-induced optical chirality, whose magnitude matched our simulations. Furthermore, we utilized two novel methods for engineering the chirality and accurately tuning the CD signals: incorporating mechanical shaking to CVF and stacking films with predesigned twist angles.