Ultrasensitive Circularly Polarized Photon Detectors Based on Chiral Two-Dimensional MoS₂

Engineering chiral optical and electronic properties of materials is interesting for applications in sensing and quantum information. State-of-the-art chiral optoelectronic devices are mostly based on three-dimensional (3D) and quasi-two-dimensional (2D) materials. Here we demonstrate chiral 2D MoS₂ with sub-nanometer thickness via chirality transfer from l-/d-penicillamine (l-/d-PEN). We report a giant molar ellipticity of 10⁸ deg·cm²/dmol in monolayer solid-state films, up to 3 orders of magnitude higher than 3D chiral materials. Phototransistors with chiral 2D MoS₂ channels exhibit gate-tunable circularly polarized light detection with responsivity of >10² A/W and anisotropy g-factor of 1.98, close to the theoretical maximum of 2.0. The reduced dimensionality magnifies the chirality transfer efficiency, allowing realization of ultrasensitive detectors for circularly polarized photons.