Transforming achiral semiconductors into chiral domains with exceptional circular dichroism
Thomas J. Ugras, R. Carson, Reilly P. Lynch, Haoyang Li, Yuan Yao, Lorenzo Cupellini, Kirt A. Page, Da Wang, Arantxa Arbe, Sara Bals, Louisa Smieska, Arthur R. Woll, Oriol Arteaga, Tamás Jávorfí, Giuliano Siligardi, Gennaro Pescitelli, Steven J. Weinstein, Richard D. Robinson
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. 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.