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Highly concentrated solutions of asymmetric semiconductor magic-sized clusters (MSCs) of cadmium sulfide, cadmium selenide, and cadmium telluride were directed through a controlled drying meniscus front, resulting in the formation of chiral MSC assemblies. This process aligned their transition dipole moments and produced chiroptic films with exceptionally strong circular dichroism.G-factors reached magnitudes as high as 1.30 for drop-cast films and 1.06 for patterned films, approaching theoretical limits. By controlling the evaporation geometry, various domain shapes and sizes were achieved, with homochiral domains exceeding 6 square millimeters that transition smoothly between left- and right-handed chirality. Our results uncovered fundamental relationships between meniscus deposition processes, the alignment of supramolecular filaments and their MSC constituents, and their connection to emergent chiral properties. 

Abstract Metal‐halide perovskites are known for their strong and tunable luminescence. However, the synthesis of perovskite‐based particles with circularly polarized light emission (CPLE) remains challenging due to the complex interplay of metal‐ligand chemistries, crystallization patterns, and chirality transfer mechanisms. Achiral perovskites can be deposited on chiral “hedgehog” particles (CHIPs) with twisted spikes, producing chiroptically active materials with spectroscopic bands specific to the perovskite and chirality specific to the template CHIPs. Left‐ and right‐handed CPLE is engineered into complex particles comprised of a layer of perovskite deposited onto CHIPs coated with an intermediate silica layer. The spectral position of chiroptical bands, the optical asymmetryg‐factors, and single‐particle circularly polarized microscopy indicate that the observed CPLE is dominated by the post‐emission scattering from the twisted spikes of the parent particle. Templating luminescent nanofilms on CHIPs provides a simple pathway to a wide range of complex chiroptical materials; the dispersibility of the CHIPs in various solvents and the tunability of their chiral geometry enable their applications as single‐particle emitters with strong and controllable polarization rotation. 

Abstract Branched plasmonic nanocrystals (NCs) have attracted much attention due to electric field enhancements at their tips. Seeded growth provides routes to NCs with defined branching patterns and, in turn, near‐field distributions with defined symmetries. Here, a systematic analysis was undertaken in which seeds containing different distributions of planar defects were used to grow branched NCs in order to understand how their distributions direct the branching. Characterization of the products by multimode electron tomography and analysis of the NC morphologies at different overgrowth stages indicate that the branching patterns are directed by the seed defects, with the emergence of branches from the seed faces consistent with minimizing volumetric strain energy at the expense of surface energy. These results contrast with growth of branched NCs from single‐crystalline seeds and provide a new platform for the synthesis of symmetrically branched plasmonic NCs.