Transforming achiral semiconductors into chiral domains with exceptional circular dichroism.

Ugras, Thomas J; Carson, River B; Lynch, Reilly P; Li, Haoyang; Yao, Yuan; Cupellini, Lorenzo; Page, Kirt A; Wang, Da et al. · Science · 2025

basic_science · Level V

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Abstract

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. <i>G</i>-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.