Flat-optics hybrid MoS ₂ /polymer films for photochemical conversion

Novel light harvesting platforms and strategies are crucial to develop renewable photon to energy conversion technologies that overcome the current global energy and environmental challenges. Two-dimensional (2D) transition metal dichalcogenide (TMD) semiconductor layers are particularly attractive for photoconversion applications but new ultra-compact photon harvesting schemes are urgently required to mitigate their poor photon absorption properties. Here, we propose a flat-optics scheme based on nanogrooved ultra-thin MoS₂ layers conformally grown onto large area (cm² scale) nanopatterned templates. The subwavelength re-shaping of the 2D-TMD layers promotes the excitation of photonic Rayleigh anomaly (RA) modes, uniquely boosting a strong in-plane electromagnetic confinement. By tailoring the illumination conditions, we demonstrate effective tuning of the photonic anomalies over a broadband visible spectrum across the absorption band of relevant polluting dye molecules. Thanks to the strong photonic in-plane confinement, we achieve a resonant enhancement of the photodissociation rate of methylene blue (MB) molecules, well above a factor of 2. These results highlight the potential of flat-optics photon harvesting schemes for boosting photoconversion efficiency in large-scale hybrid 2D-TMD/polymer layers, with a strong impact in various applications ranging from new-generation photonics to waste water remediation and renewable energy storage.