Chiroptical Response Inversion And Enhancement of Room-Temperature Exciton-Polaritons Using Two-Dimensional Chirality in Perovskites.

Although chiral semiconductors have shown promising progress in direct circularly polarized light (CPL) detection and emission, they still face potential challenges. A chirality-switching mechanism or approach integrating two enantiomers is needed to discriminate the handedness of a given CPL; additionally, a large material volume is required for sufficient chiroptical interaction. These two requirements pose significant obstacles to the simplification and miniaturization of the devices. Here, w e demonstrate room-temperature chiral polaritons fulfilling dual-handedness functions and exhibiting a more-than-two-order enhancement of the chiroptical signal, by embedding a 40-nm-thick perovskite film with a two-dimensional chiroptical effect into a Fabry-Perot cavity. By mixing chiral perovskites with different crystal structures, w e accomplish a pronounced two-dimensional chiroptical effect in the perovskite film, featured by an inverted chiroptical response for counter-propagating CPL. This inversion behavior matches the photonic handedness switch during CPL circulation in the Fabry-Perot cavity, thus harvesting giant enhancement of the chiroptical response. Furthermore, affected by the unique quarter-wave-plate effects, the polariton emission achieves a chiral dissymmetry of ±4% (for the emission from the front and the back sides). The room-temperature polaritons with the strong dissymmetric chiroptical interaction should have implications on a fundamental level and future on-chip applications for bio-molecule analysis and quantum computing. This article is protected by copyright. All rights reserved.